Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/22/13
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1105 AM MST FRI DEC 20 2013
.UPDATE...
ISSUED AT 1044 AM MST FRI DEC 20 2013
LOW CLOUDS AND FOG ARE NOT DISSIPATING OVER EL PASO COUNTY AND
ALONG THE LOWER ARKANSAS RIVER VALLEY. MIDDLE CLOUD DECK OVER THE
REGION IS HAMPERING THE DISSIPATION OF THE LOW CLOUDS AND FOG.
UPDATED GRIDS FOR LOW CLOUDS AND AREAS OF FOG TO CONTINUE IN THESE
REGIONS WELL INTO THE EVENING. ALSO COOLED DAYTIME TEMPERATURES
WITH PERSISTENT CLOUDS. AS THE SURFACE HIGH MOVES EAST OF THE
REGION...COLD AIR WILL BECOME MORE SHALLOW OVERNIGHT. ANTICIPATE
LOW CLOUDS AND ANY FOG WILL SETTLE ALONG THE ARKANSAS RIVER VALLEY
BY SUNRISE.
UPDATE ISSUED AT 927 AM MST FRI DEC 20 2013
UPDATED GRIDS TO HAVE FOG PERSIST UNTIL EARLY AFTERNOON OVER EL
PASO COUNTY. PERSISTENT SOUTHERLY FLOW SHOULD KEEP LOW CLOUDS AND
FOG OVER EL PASO COUNTY. COLD AIR IS FAIRLY SHALLOW SO THERE IS
HOPE THE FOG AND LOW CLOUDS WILL DISSIPATE BY EARLY AFTERNOON.
ABOVE THE FOG AND LOW CLOUDS...THERE ARE SOME MIDDLE AND HIGH
LEVEL CLOUDS. WILL HAVE TO MONITOR EROSION OF LOW CLOUDS OVER EL
PASO COUNTY AND MAY HAVE TO EXTEND FOG FURTHER INTO THE AFTERNOON.
--PGW--
UPDATE ISSUED AT 542 AM MST FRI DEC 20 2013
UPDATED THE FORECAST TO ADD FZFG TO EL PASO COUNTY FOR THE
MORNING HOURS. LIGHT PRECIP WILL LIKELY NOT MEASURE SO WILL LEAVE
AREA LOW POPS INTACT. ROSE
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM MST FRI DEC 20 2013
...MUCH COOLER TODAY...
...SNOW CHANCES NOT LOOKING TOO GREAT...
CURRENTLY...SOME LIGHT SHSN OVER THE WRN PORTION OF THE
STATE...MAINLY INVOF KGJT. SOME LIGHT PRECIP ALSO LIKELY MOVING INTO
THE SAWATCH RANGE AND CONTDVD THRU THE MORNING HOURS. TEMPS MAINLY
IN THE 20S...WITH SOME SINGLE DIGITS FOR THE HIGH VALLEYS. EXTENSIVE
LOW CLOUD DECK NOW COVERING THE ERN PLAINS...BUT FAIRLY SHALLOW AND
THE ERN MTS ARE ACTUALLY RELATIVELY CLEAR THIS MORN.
MAIN QUESTION TODAY IS HOW LONG THE LOW CLOUDS WILL TAKE TO BREAK UP
OVER THE PLAINS. THIS WILL DETERMINE POTENTIAL HIGH TEMPS TODAY.
CURRENT MODEL SOUNDINGS ARE NOT VERY HELPFUL...WITH THE NAM BREAKING
THINGS OUT PRETTY EARLY AND THE RAP HOLDING ON TO A LOW CLOUD DECK
THROUGH THE EARLY AFTERNOON. GIVEN THE PRETTY STOUT LLVL INVERSION
AS ALREADY HINTED OUT IN THE 00Z DEN SOUNDING...AND THE GENERALLY
LIGHT UPSLOPE WINDS EXPECTED OVER THE PLAINS...WILL LEAN TOWARDS A
LATER TIME FOR THE LOW CIGS TO DISSIPATE. THIS WILL KEEP AFTERNOON
HIGHS FROM REACHING THE POTENTIAL SUGGESTED BY H7 TEMPS ONLY A FEW
DEGREES BELOW ZERO. HAVE CUT BACK TEMPS A FEW DEGREES FROM CURRENT
FORECAST...BUT SOME GUIDANCE SUGGESTS THEY MAY EVEN END UP LOWER
THAN FORECAST. BOTTOM LINE...IT WILL BE A GOOD 20 DEGREES COOLER
THAN YESTERDAY...AND FINALLY FEEL LIKE DECEMBER FOR SERN CO.
SNOW POTENTIAL IS NOT LOOKING TOO GREAT TODAY. A NUMBER OF MODEL
SOUNDINGS SUGGEST SOME LIGHT PRECIP OVER THE PLAINS THIS MORN...BUT
GIVEN THE RELATIVELY SHALLOW CLOUD LAYER DO NOT EXPECT ANYTHING THAT
FALLS TO ACCUMULATE OR EVEN MEASURE. SO...HAVE KEPT POPS LOW FOR THE
PLAINS THROUGH TONIGHT. PERSISTENT LIGHT SHSN WILL BE ONGOING OVER
THE CONTDVD AND WILL PICK UP GRADUALLY AS WE GO THROUGH THE
AFTERNOON BEFORE TAPERING OFF THIS EVENING. BUT ACCUMS NOT LOOKING
TOO IMPRESSIVE WITH AT BEST A FEW INCHES OVER THE DVD BY SUN MORNING.
WITH SOME PARTIAL CLEARING TONIGHT AND LIGHT WINDS...TEMPS WILL BE
ON THE COLD SIDE...WITH SOME TEENS POSSIBLE FOR THE PLAINS AND
CONTINUED SINGLE DIGITS AND NEGATIVE READINGS FOR THE MTS AND HIGH
VALLEYS. ROSE
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 250 AM MST FRI DEC 20 2013
SATURDAY INTO SUNDAY APPEARS TO BE THE MOST ACTIVE WX PD DURING THIS
FORECAST SEGMENT. THE SOUTHERN STORM TRACKING OVER NM MAY CLIP THE
FAR SE CORNER OF COLORADO...WHILE THE NORTHERN SYSTEM WILL LIKELY
BRING SNOW TO THE MOUNTAINS AND POSSIBLY PARTS OF THE I-25 CORRIDOR.
FOR THE FAR SE PLAINS...IT APPEARS THE BEST CHANCE OF BACA COUNTY
SEEING ANY PRECIP WILL BE SAT AFTERNOON AND EVENING. BOTH GFS AND EC
HAVE AN IMPRESSIVE BAND OF PRECIP DEVELOPING OVER THE N TX PHDL INTO
THE OK PHDL...WITH THE N PARTS OF THIS BAND ENTERING INTO SE BACA
COUNTY. ON THE OTHER HAND THE NAM (00Z AND 06Z RUNS) KEEP THE PRECIP
DOWN INTO TX. I HAVE LEANED TOWARDS THE GFS AND EC BUT HAVE
DECREASED POPS A BIT OVER THE BACA COUNTY REGION TO ACCOUNT FOR THE
TRENDS IN THE NAM GUIDANCE.
THE N TIER SYSTEM WILL DROP INTO CO DURING SAT MORNING AND MOVE
ACROSS THE REGION SAT NITE. SNOW IN THE C MTNS IS LIKELY...WITH A
GOOD CHANCE OF SNOW OVER MOST OF THE OTHER MTNS DURING THE LATTER
AFTERNOON AND EVENING HOURS. IT DOES NOT APPEAR THAT ANY SIGNIF
ACCUMS WILL OCCUR...BUT 2-3" IS NOT OUT OF THE QUESTION...ESPECIALLY
ON THE NW SLOPES. SOME SNOW SHOWERS MAY MAKE IT OUT ONTO THE I-25
CORRIDOR...ESPECIALLY SAT EVE/NITE.
DRY AND COOL WX WILL BE LIKELY LATER SUNDAY INTO EARLY TUESDAY.
TUESDAY..XMAS EVE..MAY BE RATHER QUITE NICE GIVEN THE LEE TROUGH AND
DOWNSLOPE. TEMPS ON THE PLAINS WILL LIKELY BE IN THE 50S WITH A 60
OR TWO POSSIBLE.
BY LATE TUESDAY/TUE NITE ANOTHER COLD FRONT WILL MOVE ACROSS THE
REGION. HOWEVER...THIS SYSTEM LOOKS WEAKER ON BOTH THE EC AND GFS
AND THE CHANCE OF SNOW IS DECREASING FOR XMAS EVE INTO XMAS FOR THE
ENTIRE REGION. I HAVE NOT REMOVED POPS COMPLETELY...BUT THE TREND IN THE
GUIDANCE IS SHOWING THE SNOW CHANCES FOR THE LOWER ELEVATIONS
DECREASING. I WOULD NOT BE TOO SURPRISED IF LATER SHIFTS REMOVE THE
POPS COMPLETELY FOR THE LOWER ELEVATIONS XMAS EVE INTO XMAS. TEMPS
XMAS DAY WILL BE A GOOD 10-20F COOLER THAN XMAS EVE.
ANOTHER DISTURBANCE WILL MOVE DOWN ACROSS THE REGION ON FRIDAY
BRINGING ANOTHER COOL FRONT TO THE REGION. /HODANISH
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1044 AM MST FRI DEC 20 2013
SHALLOW POLAR AIR MASS WILL REMAIN OVER INTERSTATE 25 CORRIDOR AND
EASTERN PLAINS WELL INTO THE EVENING. WITH PERSISTENT WEAK
SOUTHERLY FLOW...ANTICIPATE KCOS AND KPUB WILL STAY IN LOWER MVFR
TO IFR CONDITIONS THROUGHOUT THE DAY AND INTO THE EVENING. AS THE
COLD AIR BECOMES SHALLOW TONIGHT...EXPECT IMPROVING CONDITIONS TO
DESCEND SOUTHWARD OVER EL PASO COUNTY. OFTEN...CAN SEE A RAPID
IMPROVEMENT AT KCOS WHEN THIS HAPPENS. BEST ESTIMATE AT THIS TIME
IS TO HAVE CONDITIONS IMPROVE AROUND MIDNIGHT. IF WEAK EASTERLY
FLOW PERSISTS ALONG ARKANSAS RIVER...KPUB COULD STAY IFR UNTIL
SUNRISE.
KALS...WEAK DISTURBANCE PASSING OVERHEAD AND MIDDLE LEVEL CLOUDS
SHOULD HAMPER FOG DEVELOPMENT TONIGHT.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PGW
SHORT TERM...ROSE
LONG TERM...HODANISH
AVIATION...PGW
AREA FORECAST DISCUSSION
NWS PUEBLO CO
934 AM MST FRI DEC 20 2013
.UPDATE...
ISSUED AT 927 AM MST FRI DEC 20 2013
UPDATED GRIDS TO HAVE FOG PERSIST UNTIL EARLY AFTERNOON OVER EL
PASO COUNTY. PERSISTENT SOUTHERLY FLOW SHOULD KEEP LOW CLOUDS AND
FOG OVER EL PASO COUNTY. COLD AIR IS FAIRLY SHALLOW SO THERE IS
HOPE THE FOG AND LOW CLOUDS WILL DISSIPATE BY EARLY AFTERNOON.
ABOVE THE FOG AND LOW CLOUDS...THERE ARE SOME MIDDLE AND HIGH
LEVEL CLOUDS. WILL HAVE TO MONITOR EROSION OF LOW CLOUDS OVER EL
PASO COUNTY AND MAY HAVE TO EXTEND FOG FURTHER INTO THE AFTERNOON.
--PGW--
UPDATE ISSUED AT 542 AM MST FRI DEC 20 2013
UPDATED THE FORECAST TO ADD FZFG TO EL PASO COUNTY FOR THE
MORNING HOURS. LIGHT PRECIP WILL LIKELY NOT MEASURE SO WILL LEAVE
AREA LOW POPS INTACT. ROSE
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM MST FRI DEC 20 2013
...MUCH COOLER TODAY...
...SNOW CHANCES NOT LOOKING TOO GREAT...
CURRENTLY...SOME LIGHT SHSN OVER THE WRN PORTION OF THE
STATE...MAINLY INVOF KGJT. SOME LIGHT PRECIP ALSO LIKELY MOVING INTO
THE SAWATCH RANGE AND CONTDVD THRU THE MORNING HOURS. TEMPS MAINLY
IN THE 20S...WITH SOME SINGLE DIGITS FOR THE HIGH VALLEYS. EXTENSIVE
LOW CLOUD DECK NOW COVERING THE ERN PLAINS...BUT FAIRLY SHALLOW AND
THE ERN MTS ARE ACTUALLY RELATIVELY CLEAR THIS MORN.
MAIN QUESTION TODAY IS HOW LONG THE LOW CLOUDS WILL TAKE TO BREAK UP
OVER THE PLAINS. THIS WILL DETERMINE POTENTIAL HIGH TEMPS TODAY.
CURRENT MODEL SOUNDINGS ARE NOT VERY HELPFUL...WITH THE NAM BREAKING
THINGS OUT PRETTY EARLY AND THE RAP HOLDING ON TO A LOW CLOUD DECK
THROUGH THE EARLY AFTERNOON. GIVEN THE PRETTY STOUT LLVL INVERSION
AS ALREADY HINTED OUT IN THE 00Z DEN SOUNDING...AND THE GENERALLY
LIGHT UPSLOPE WINDS EXPECTED OVER THE PLAINS...WILL LEAN TOWARDS A
LATER TIME FOR THE LOW CIGS TO DISSIPATE. THIS WILL KEEP AFTERNOON
HIGHS FROM REACHING THE POTENTIAL SUGGESTED BY H7 TEMPS ONLY A FEW
DEGREES BELOW ZERO. HAVE CUT BACK TEMPS A FEW DEGREES FROM CURRENT
FORECAST...BUT SOME GUIDANCE SUGGESTS THEY MAY EVEN END UP LOWER
THAN FORECAST. BOTTOM LINE...IT WILL BE A GOOD 20 DEGREES COOLER
THAN YESTERDAY...AND FINALLY FEEL LIKE DECEMBER FOR SERN CO.
SNOW POTENTIAL IS NOT LOOKING TOO GREAT TODAY. A NUMBER OF MODEL
SOUNDINGS SUGGEST SOME LIGHT PRECIP OVER THE PLAINS THIS MORN...BUT
GIVEN THE RELATIVELY SHALLOW CLOUD LAYER DO NOT EXPECT ANYTHING THAT
FALLS TO ACCUMULATE OR EVEN MEASURE. SO...HAVE KEPT POPS LOW FOR THE
PLAINS THROUGH TONIGHT. PERSISTENT LIGHT SHSN WILL BE ONGOING OVER
THE CONTDVD AND WILL PICK UP GRADUALLY AS WE GO THROUGH THE
AFTERNOON BEFORE TAPERING OFF THIS EVENING. BUT ACCUMS NOT LOOKING
TOO IMPRESSIVE WITH AT BEST A FEW INCHES OVER THE DVD BY SUN MORNING.
WITH SOME PARTIAL CLEARING TONIGHT AND LIGHT WINDS...TEMPS WILL BE
ON THE COLD SIDE...WITH SOME TEENS POSSIBLE FOR THE PLAINS AND
CONTINUED SINGLE DIGITS AND NEGATIVE READINGS FOR THE MTS AND HIGH
VALLEYS. ROSE
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 250 AM MST FRI DEC 20 2013
SATURDAY INTO SUNDAY APPEARS TO BE THE MOST ACTIVE WX PD DURING THIS
FORECAST SEGMENT. THE SOUTHERN STORM TRACKING OVER NM MAY CLIP THE
FAR SE CORNER OF COLORADO...WHILE THE NORTHERN SYSTEM WILL LIKELY
BRING SNOW TO THE MOUNTAINS AND POSSIBLY PARTS OF THE I-25 CORRIDOR.
FOR THE FAR SE PLAINS...IT APPEARS THE BEST CHANCE OF BACA COUNTY
SEEING ANY PRECIP WILL BE SAT AFTERNOON AND EVENING. BOTH GFS AND EC
HAVE AN IMPRESSIVE BAND OF PRECIP DEVELOPING OVER THE N TX PHDL INTO
THE OK PHDL...WITH THE N PARTS OF THIS BAND ENTERING INTO SE BACA
COUNTY. ON THE OTHER HAND THE NAM (00Z AND 06Z RUNS) KEEP THE PRECIP
DOWN INTO TX. I HAVE LEANED TOWARDS THE GFS AND EC BUT HAVE
DECREASED POPS A BIT OVER THE BACA COUNTY REGION TO ACCOUNT FOR THE
TRENDS IN THE NAM GUIDANCE.
THE N TIER SYSTEM WILL DROP INTO CO DURING SAT MORNING AND MOVE
ACROSS THE REGION SAT NITE. SNOW IN THE C MTNS IS LIKELY...WITH A
GOOD CHANCE OF SNOW OVER MOST OF THE OTHER MTNS DURING THE LATTER
AFTERNOON AND EVENING HOURS. IT DOES NOT APPEAR THAT ANY SIGNIF
ACCUMS WILL OCCUR...BUT 2-3" IS NOT OUT OF THE QUESTION...ESPECIALLY
ON THE NW SLOPES. SOME SNOW SHOWERS MAY MAKE IT OUT ONTO THE I-25
CORRIDOR...ESPECIALLY SAT EVE/NITE.
DRY AND COOL WX WILL BE LIKELY LATER SUNDAY INTO EARLY TUESDAY.
TUESDAY..XMAS EVE..MAY BE RATHER QUITE NICE GIVEN THE LEE TROUGH AND
DOWNSLOPE. TEMPS ON THE PLAINS WILL LIKELY BE IN THE 50S WITH A 60
OR TWO POSSIBLE.
BY LATE TUESDAY/TUE NITE ANOTHER COLD FRONT WILL MOVE ACROSS THE
REGION. HOWEVER...THIS SYSTEM LOOKS WEAKER ON BOTH THE EC AND GFS
AND THE CHANCE OF SNOW IS DECREASING FOR XMAS EVE INTO XMAS FOR THE
ENTIRE REGION. I HAVE NOT REMOVED POPS COMPLETELY...BUT THE TREND IN THE
GUIDANCE IS SHOWING THE SNOW CHANCES FOR THE LOWER ELEVATIONS
DECREASING. I WOULD NOT BE TOO SURPRISED IF LATER SHIFTS REMOVE THE
POPS COMPLETELY FOR THE LOWER ELEVATIONS XMAS EVE INTO XMAS. TEMPS
XMAS DAY WILL BE A GOOD 10-20F COOLER THAN XMAS EVE.
ANOTHER DISTURBANCE WILL MOVE DOWN ACROSS THE REGION ON FRIDAY
BRINGING ANOTHER COOL FRONT TO THE REGION. /HODANISH
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 250 AM MST FRI DEC 20 2013
MAIN QUESTION IS HOW QUICKLY IFR-MVFR CIGS WILL CLEAR FROM THE
PLAINS TODAY. WITH GENERALLY LIGHT UPSLOPE WINDS AND STRONG
TEMPERATURE INVERSIONS...EXPECT CIGS TO STAY LOW FOR A GOOD PORTION
OF THIS MORNING AND POSSIBLY THROUGH THE AFTERNOON...FOR KPUB FROM
17-18Z...AND AT KCOS 18-19Z. NO ACCUMULATING PRECIP IS EXPECTED BUT
SOME LIGHT PRECIP WILL BE POSSIBLE WITHIN THE LOW CLOUD DECK...WITH
TOPS BREAKING OUT ONLY 1000 FT OR SO AGL. VFR CONDITIONS WILL THEN
PERSIST THROUGH SUN MORNING. LIGHT SHSN WILL CONTINUE THROUGH THIS
EVE OVER THE CONTDVD...WITH MT TOPS OBSCURED DURING THIS PERIOD.
AT KALS...SOME LOCAL PC FG OR BR POSSIBLE THROUGH 15-16Z...AND AGAIN
LATE TONIGHT...BUT WILL STICK WITH A PERSISTENCE FORECAST FOR NOW IN
THE TAFS AND LEAVE CONDITIONS VFR. ROSE
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...PGW
SHORT TERM...ROSE
LONG TERM...HODANISH
AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
545 AM MST FRI DEC 20 2013
.UPDATE...
ISSUED AT 542 AM MST FRI DEC 20 2013
UPDATED THE FORECAST TO ADD FZFG TO EL PASO COUNTY FOR THE
MORNING HOURS. LIGHT PRECIP WILL LIKELY NOT MEASURE SO WILL LEAVE
AREA LOW POPS INTACT. ROSE
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM MST FRI DEC 20 2013
...MUCH COOLER TODAY...
...SNOW CHANCES NOT LOOKING TOO GREAT...
CURRENTLY...SOME LIGHT SHSN OVER THE WRN PORTION OF THE
STATE...MAINLY INVOF KGJT. SOME LIGHT PRECIP ALSO LIKELY MOVING INTO
THE SAWATCH RANGE AND CONTDVD THRU THE MORNING HOURS. TEMPS MAINLY
IN THE 20S...WITH SOME SINGLE DIGITS FOR THE HIGH VALLEYS. EXTENSIVE
LOW CLOUD DECK NOW COVERING THE ERN PLAINS...BUT FAIRLY SHALLOW AND
THE ERN MTS ARE ACTUALLY RELATIVELY CLEAR THIS MORN.
MAIN QUESTION TODAY IS HOW LONG THE LOW CLOUDS WILL TAKE TO BREAK UP
OVER THE PLAINS. THIS WILL DETERMINE POTENTIAL HIGH TEMPS TODAY.
CURRENT MODEL SOUNDINGS ARE NOT VERY HELPFUL...WITH THE NAM BREAKING
THINGS OUT PRETTY EARLY AND THE RAP HOLDING ON TO A LOW CLOUD DECK
THROUGH THE EARLY AFTERNOON. GIVEN THE PRETTY STOUT LLVL INVERSION
AS ALREADY HINTED OUT IN THE 00Z DEN SOUNDING...AND THE GENERALLY
LIGHT UPSLOPE WINDS EXPECTED OVER THE PLAINS...WILL LEAN TOWARDS A
LATER TIME FOR THE LOW CIGS TO DISSIPATE. THIS WILL KEEP AFTERNOON
HIGHS FROM REACHING THE POTENTIAL SUGGESTED BY H7 TEMPS ONLY A FEW
DEGREES BELOW ZERO. HAVE CUT BACK TEMPS A FEW DEGREES FROM CURRENT
FORECAST...BUT SOME GUIDANCE SUGGESTS THEY MAY EVEN END UP LOWER
THAN FORECAST. BOTTOM LINE...IT WILL BE A GOOD 20 DEGREES COOLER
THAN YESTERDAY...AND FINALLY FEEL LIKE DECEMBER FOR SERN CO.
SNOW POTENTIAL IS NOT LOOKING TOO GREAT TODAY. A NUMBER OF MODEL
SOUNDINGS SUGGEST SOME LIGHT PRECIP OVER THE PLAINS THIS MORN...BUT
GIVEN THE RELATIVELY SHALLOW CLOUD LAYER DO NOT EXPECT ANYTHING THAT
FALLS TO ACCUMULATE OR EVEN MEASURE. SO...HAVE KEPT POPS LOW FOR THE
PLAINS THROUGH TONIGHT. PERSISTENT LIGHT SHSN WILL BE ONGOING OVER
THE CONTDVD AND WILL PICK UP GRADUALLY AS WE GO THROUGH THE
AFTERNOON BEFORE TAPERING OFF THIS EVENING. BUT ACCUMS NOT LOOKING
TOO IMPRESSIVE WITH AT BEST A FEW INCHES OVER THE DVD BY SUN MORNING.
WITH SOME PARTIAL CLEARING TONIGHT AND LIGHT WINDS...TEMPS WILL BE
ON THE COLD SIDE...WITH SOME TEENS POSSIBLE FOR THE PLAINS AND
CONTINUED SINGLE DIGITS AND NEGATIVE READINGS FOR THE MTS AND HIGH
VALLEYS. ROSE
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 250 AM MST FRI DEC 20 2013
SATURDAY INTO SUNDAY APPEARS TO BE THE MOST ACTIVE WX PD DURING THIS
FORECAST SEGMENT. THE SOUTHERN STORM TRACKING OVER NM MAY CLIP THE
FAR SE CORNER OF COLORADO...WHILE THE NORTHERN SYSTEM WILL LIKELY
BRING SNOW TO THE MOUNTAINS AND POSSIBLY PARTS OF THE I-25 CORRIDOR.
FOR THE FAR SE PLAINS...IT APPEARS THE BEST CHANCE OF BACA COUNTY
SEEING ANY PRECIP WILL BE SAT AFTERNOON AND EVENING. BOTH GFS AND EC
HAVE AN IMPRESSIVE BAND OF PRECIP DEVELOPING OVER THE N TX PHDL INTO
THE OK PHDL...WITH THE N PARTS OF THIS BAND ENTERING INTO SE BACA
COUNTY. ON THE OTHER HAND THE NAM (00Z AND 06Z RUNS) KEEP THE PRECIP
DOWN INTO TX. I HAVE LEANED TOWARDS THE GFS AND EC BUT HAVE
DECREASED POPS A BIT OVER THE BACA COUNTY REGION TO ACCOUNT FOR THE
TRENDS IN THE NAM GUIDANCE.
THE N TIER SYSTEM WILL DROP INTO CO DURING SAT MORNING AND MOVE
ACROSS THE REGION SAT NITE. SNOW IN THE C MTNS IS LIKELY...WITH A
GOOD CHANCE OF SNOW OVER MOST OF THE OTHER MTNS DURING THE LATTER
AFTERNOON AND EVENING HOURS. IT DOES NOT APPEAR THAT ANY SIGNIF
ACCUMS WILL OCCUR...BUT 2-3" IS NOT OUT OF THE QUESTION...ESPECIALLY
ON THE NW SLOPES. SOME SNOW SHOWERS MAY MAKE IT OUT ONTO THE I-25
CORRIDOR...ESPECIALLY SAT EVE/NITE.
DRY AND COOL WX WILL BE LIKELY LATER SUNDAY INTO EARLY TUESDAY.
TUESDAY..XMAS EVE..MAY BE RATHER QUITE NICE GIVEN THE LEE TROUGH AND
DOWNSLOPE. TEMPS ON THE PLAINS WILL LIKELY BE IN THE 50S WITH A 60
OR TWO POSSIBLE.
BY LATE TUESDAY/TUE NITE ANOTHER COLD FRONT WILL MOVE ACROSS THE
REGION. HOWEVER...THIS SYSTEM LOOKS WEAKER ON BOTH THE EC AND GFS
AND THE CHANCE OF SNOW IS DECREASING FOR XMAS EVE INTO XMAS FOR THE
ENTIRE REGION. I HAVE NOT REMOVED POPS COMPLETELY...BUT THE TREND IN THE
GUIDANCE IS SHOWING THE SNOW CHANCES FOR THE LOWER ELEVATIONS
DECREASING. I WOULD NOT BE TOO SURPRISED IF LATER SHIFTS REMOVE THE
POPS COMPLETELY FOR THE LOWER ELEVATIONS XMAS EVE INTO XMAS. TEMPS
XMAS DAY WILL BE A GOOD 10-20F COOLER THAN XMAS EVE.
ANOTHER DISTURBANCE WILL MOVE DOWN ACROSS THE REGION ON FRIDAY
BRINGING ANOTHER COOL FRONT TO THE REGION. /HODANISH
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 250 AM MST FRI DEC 20 2013
MAIN QUESTION IS HOW QUICKLY IFR-MVFR CIGS WILL CLEAR FROM THE
PLAINS TODAY. WITH GENERALLY LIGHT UPSLOPE WINDS AND STRONG
TEMPERATURE INVERSIONS...EXPECT CIGS TO STAY LOW FOR A GOOD PORTION
OF THIS MORNING AND POSSIBLY THROUGH THE AFTERNOON...FOR KPUB FROM
17-18Z...AND AT KCOS 18-19Z. NO ACCUMULATING PRECIP IS EXPECTED BUT
SOME LIGHT PRECIP WILL BE POSSIBLE WITHIN THE LOW CLOUD DECK...WITH
TOPS BREAKING OUT ONLY 1000 FT OR SO AGL. VFR CONDITIONS WILL THEN
PERSIST THROUGH SUN MORNING. LIGHT SHSN WILL CONTINUE THROUGH THIS
EVE OVER THE CONTDVD...WITH MT TOPS OBSCURED DURING THIS PERIOD.
AT KALS...SOME LOCAL PC FG OR BR POSSIBLE THROUGH 15-16Z...AND AGAIN
LATE TONIGHT...BUT WILL STICK WITH A PERSISTENCE FORECAST FOR NOW IN
THE TAFS AND LEAVE CONDITIONS VFR. ROSE
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...ROSE
SHORT TERM...ROSE
LONG TERM...HODANISH
AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS PUEBLO CO
258 AM MST FRI DEC 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 250 AM MST FRI DEC 20 2013
...MUCH COOLER TODAY...
...SNOW CHANCES NOT LOOKING TOO GREAT...
CURRENTLY...SOME LIGHT SHSN OVER THE WRN PORTION OF THE
STATE...MAINLY INVOF KGJT. SOME LIGHT PRECIP ALSO LIKELY MOVING INTO
THE SAWATCH RANGE AND CONTDVD THRU THE MORNING HOURS. TEMPS MAINLY
IN THE 20S...WITH SOME SINGLE DIGITS FOR THE HIGH VALLEYS. EXTENSIVE
LOW CLOUD DECK NOW COVERING THE ERN PLAINS...BUT FAIRLY SHALLOW AND
THE ERN MTS ARE ACTUALLY RELATIVELY CLEAR THIS MORN.
MAIN QUESTION TODAY IS HOW LONG THE LOW CLOUDS WILL TAKE TO BREAK UP
OVER THE PLAINS. THIS WILL DETERMINE POTENTIAL HIGH TEMPS TODAY.
CURRENT MODEL SOUNDINGS ARE NOT VERY HELPFUL...WITH THE NAM BREAKING
THINGS OUT PRETTY EARLY AND THE RAP HOLDING ON TO A LOW CLOUD DECK
THROUGH THE EARLY AFTERNOON. GIVEN THE PRETTY STOUT LLVL INVERSION
AS ALREADY HINTED OUT IN THE 00Z DEN SOUNDING...AND THE GENERALLY
LIGHT UPSLOPE WINDS EXPECTED OVER THE PLAINS...WILL LEAN TOWARDS A
LATER TIME FOR THE LOW CIGS TO DISSIPATE. THIS WILL KEEP AFTERNOON
HIGHS FROM REACHING THE POTENTIAL SUGGESTED BY H7 TEMPS ONLY A FEW
DEGREES BELOW ZERO. HAVE CUT BACK TEMPS A FEW DEGREES FROM CURRENT
FORECAST...BUT SOME GUIDANCE SUGGESTS THEY MAY EVEN END UP LOWER
THAN FORECAST. BOTTOM LINE...IT WILL BE A GOOD 20 DEGREES COOLER
THAN YESTERDAY...AND FINALLY FEEL LIKE DECEMBER FOR SERN CO.
SNOW POTENTIAL IS NOT LOOKING TOO GREAT TODAY. A NUMBER OF MODEL
SOUNDINGS SUGGEST SOME LIGHT PRECIP OVER THE PLAINS THIS MORN...BUT
GIVEN THE RELATIVELY SHALLOW CLOUD LAYER DO NOT EXPECT ANYTHING THAT
FALLS TO ACCUMULATE OR EVEN MEASURE. SO...HAVE KEPT POPS LOW FOR THE
PLAINS THROUGH TONIGHT. PERSISTENT LIGHT SHSN WILL BE ONGOING OVER
THE CONTDVD AND WILL PICK UP GRADUALLY AS WE GO THROUGH THE
AFTERNOON BEFORE TAPERING OFF THIS EVENING. BUT ACCUMS NOT LOOKING
TOO IMPRESSIVE WITH AT BEST A FEW INCHES OVER THE DVD BY SUN MORNING.
WITH SOME PARTIAL CLEARING TONIGHT AND LIGHT WINDS...TEMPS WILL BE
ON THE COLD SIDE...WITH SOME TEENS POSSIBLE FOR THE PLAINS AND
CONTINUED SINGLE DIGITS AND NEGATIVE READINGS FOR THE MTS AND HIGH
VALLEYS. ROSE
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 250 AM MST FRI DEC 20 2013
SATURDAY INTO SUNDAY APPEARS TO BE THE MOST ACTIVE WX PD DURING THIS
FORECAST SEGMENT. THE SOUTHERN STORM TRACKING OVER NM MAY CLIP THE
FAR SE CORNER OF COLORADO...WHILE THE NORTHERN SYSTEM WILL LIKELY
BRING SNOW TO THE MOUNTAINS AND POSSIBLY PARTS OF THE I-25 CORRIDOR.
FOR THE FAR SE PLAINS...IT APPEARS THE BEST CHANCE OF BACA COUNTY
SEEING ANY PRECIP WILL BE SAT AFTERNOON AND EVENING. BOTH GFS AND EC
HAVE AN IMPRESSIVE BAND OF PRECIP DEVELOPING OVER THE N TX PHDL INTO
THE OK PHDL...WITH THE N PARTS OF THIS BAND ENTERING INTO SE BACA
COUNTY. ON THE OTHER HAND THE NAM (00Z AND 06Z RUNS) KEEP THE PRECIP
DOWN INTO TX. I HAVE LEANED TOWARDS THE GFS AND EC BUT HAVE
DECREASED POPS A BIT OVER THE BACA COUNTY REGION TO ACCOUNT FOR THE
TRENDS IN THE NAM GUIDANCE.
THE N TIER SYSTEM WILL DROP INTO CO DURING SAT MORNING AND MOVE
ACROSS THE REGION SAT NITE. SNOW IN THE C MTNS IS LIKELY...WITH A
GOOD CHANCE OF SNOW OVER MOST OF THE OTHER MTNS DURING THE LATTER
AFTERNOON AND EVENING HOURS. IT DOES NOT APPEAR THAT ANY SIGNIF
ACCUMS WILL OCCUR...BUT 2-3" IS NOT OUT OF THE QUESTION...ESPECIALLY
ON THE NW SLOPES. SOME SNOW SHOWERS MAY MAKE IT OUT ONTO THE I-25
CORRIDOR...ESPECIALLY SAT EVE/NITE.
DRY AND COOL WX WILL BE LIKELY LATER SUNDAY INTO EARLY TUESDAY.
TUESDAY..XMAS EVE..MAY BE RATHER QUITE NICE GIVEN THE LEE TROUGH AND
DOWNSLOPE. TEMPS ON THE PLAINS WILL LIKELY BE IN THE 50S WITH A 60
OR TWO POSSIBLE.
BY LATE TUESDAY/TUE NITE ANOTHER COLD FRONT WILL MOVE ACROSS THE
REGION. HOWEVER...THIS SYSTEM LOOKS WEAKER ON BOTH THE EC AND GFS
AND THE CHANCE OF SNOW IS DECREASING FOR XMAS EVE INTO XMAS FOR THE
ENTIRE REGION. I HAVE NOT REMOVED POPS COMPLETELY...BUT THE TREND IN THE
GUIDANCE IS SHOWING THE SNOW CHANCES FOR THE LOWER ELEVATIONS
DECREASING. I WOULD NOT BE TOO SURPRISED IF LATER SHIFTS REMOVE THE
POPS COMPLETELY FOR THE LOWER ELEVATIONS XMAS EVE INTO XMAS. TEMPS
XMAS DAY WILL BE A GOOD 10-20F COOLER THAN XMAS EVE.
ANOTHER DISTURBANCE WILL MOVE DOWN ACROSS THE REGION ON FRIDAY
BRINGING ANOTHER COOL FRONT TO THE REGION. /HODANISH
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 250 AM MST FRI DEC 20 2013
MAIN QUESTION IS HOW QUICKLY IFR-MVFR CIGS WILL CLEAR FROM THE
PLAINS TODAY. WITH GENERALLY LIGHT UPSLOPE WINDS AND STRONG
TEMPERATURE INVERSIONS...EXPECT CIGS TO STAY LOW FOR A GOOD PORTION
OF THIS MORNING AND POSSIBLY THROUGH THE AFTERNOON...FOR KPUB FROM
17-18Z...AND AT KCOS 18-19Z. NO ACCUMULATING PRECIP IS EXPECTED BUT
SOME LIGHT PRECIP WILL BE POSSIBLE WITHIN THE LOW CLOUD DECK...WITH
TOPS BREAKING OUT ONLY 1000 FT OR SO AGL. VFR CONDITIONS WILL THEN
PERSIST THROUGH SUN MORNING. LIGHT SHSN WILL CONTINUE THROUGH THIS
EVE OVER THE CONTDVD...WITH MT TOPS OBSCURED DURING THIS PERIOD.
AT KALS...SOME LOCAL PC FG OR BR POSSIBLE THROUGH 15-16Z...AND AGAIN
LATE TONIGHT...BUT WILL STICK WITH A PERSISTENCE FORECAST FOR NOW IN
THE TAFS AND LEAVE CONDITIONS VFR. ROSE
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...ROSE
LONG TERM...HODANISH
AVIATION...ROSE
AREA FORECAST DISCUSSION
NWS ALBANY NY
120 PM EST FRI DEC 20 2013
.SYNOPSIS...
WAVES OF LOW PRESSURE WILL TRACK ALONG A NEARLY STATIONARY FRONT
FROM THE GREAT LAKES THROUGH NORTHERN NEW YORK AND NORTHERN NEW
ENGLAND THROUGH TONIGHT. THE FRONT WILL SINK SOUTH AS A COLD FRONT
INTO PARTS OF CENTRAL NEW YORK AND SOUTHERN VERMONT SATURDAY
NIGHT...SUPPORTING CHANCES FOR FREEZING RAIN IN THE NORTH COUNTRY.
STRONG LOW PRESSURE WILL TRACK NORTHEAST OUT OF THE TENNESSEE AND
OHIO VALLEY SUNDAY AS THE FRONT SURGES NORTH INTO CANADA...
BRINGING LOCALLY HEAVY RAIN AND WARMER TEMPERATURES TO OUR REGION.
A COLD FRONT WILL TRACK THROUGH OUR AREA SUNDAY NIGHT AND MONDAY
MORNING BRINGING A RETURN TO COLDER WEATHER FOR THE BEGINNING OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1245 PM...RADAR INDICATED FAIRLY WIDESPREAD LIGHT RAIN
OCCURRING OR WILL SHORTLY SPREAD INTO THE NORTHERN THREE-FOURTHS OF
THE FORECAST AREA. HAVE ADJUSTED POPS UPWARD TO LIKELY AND
CATEGORICAL IN THESE AREAS AND INCREASED POPS OVER THE FAR SOUTH TO
SLIGHT OR LOW CHANCE. TEMPS IN THE ADIRONDACK ZONES GENERALLY IN THE
MID OR UPPER 30S SO NO THREAT FOR ANY FREEZING RAIN FOR THE REST OF
TODAY. HAVE ADJUSTED TEMPS HIGHER...ESPECIALLY ACROSS THE HIGHER
TERRAIN WHERE THE SOUTHWEST FLOW HAS SCOURED OUT ANY REMAINING
COLDER AIR. TEMPS OVER THE HIGHER TERRAIN OF THE CATSKILLS ARE
CURRENTLY AROUND 50.
.PREVIOUS DISCUSSION...
AS OF 930 AM EST...RADARS INDICATING SOME LIGHT SPOTTY RETURNS
ACROSS MAINLY OUR NORTHERN AREAS. THE HRRR LOOKS ON CUE...WITH
LIGHTLY PRECIPITATION LIKELY TO FILL IN AS THE AFTERNOON
ARRIVES...DUE TO INCREASED CONVERGENCE AND MOISTURE ALONG AN
APPROACHING BOUNDARY.
TEMPERATURES IN THE VALLEYS GENERALLY IN THE 30S ABOVE FREEZING.
HOWEVER...MESO SITES INDICATED TEMPERATURES INTO THE 40S ACROSS
MAINLY THE HIGHER ELEVATIONS OF CATSKILLS...BUT EVEN ABOVE FREEZING
ACROSS OUR SOUTHERN ADIRONDACKS. SNOW MELT HAS COMMENCE...AND MANY
AREAS WILL LIKELY NOT DROP BACK BELOW FREEZING UNTIL SUNDAY NIGHT.
NO REAL CHANGES WITH THIS PACKAGE...TWEAKED THE POPS (DOWNWARD A
LITTLE IN THE BEGINNING GRIDS) AND OF COURSE RE-TOOLED THE HOURLY
GRIDS. LOOK FOR LOTS OF CLOUDS TODAY...AND AN INCREASING CHANCE OF
MAINLY RAIN SHOWERS THIS AFTERNOON (WITH PERHAPS SOME POCKETS OF
FREEZING RAIN UP NORTH)...MAINLY ALBANY NORTH.
HIGH TEMPERATURES THIS AFTERNOON REACHING 45-50 SOUTH OF CAPITAL
DISTRICT...40-45 CAPITAL DISTRICT AND SURROUNDING PARTS. TO THE
NORTH...HIGHS WILL GENERALLY BE 35-40.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
ONE WEAK UPPER IMPULSE AND WEAK FORCING AFFECTS OUR REGION THIS
AFTERNOON AND TONIGHT. THE BEST COVERAGE OF PRECIPITATION TONIGHT
SHOULD BE NORTH OF THE MOHAWK VALLEY AND WEST OF THE LAKE GEORGE
SARATOGA REGION. HOWEVER...SOLID CHANCES FROM SCHOHARIE VALLEY
THROUGH THE CAPITAL DISTRICT...SOUTHERN VT INTO THE BERKSHIRES AND
EASTERN CATSKILLS. PRECIPITATION AMOUNTS SHOULD BE LIGHT...BUT
NIGHTTIME COOLING IN THE SOUTHERN ADIRONDACKS COULD ALLOW SOME OF
THE PRECIPITATION TO FALL AS FREEZING RAIN...MAYBE UP TO A TENTH
OF AN INCH. HOLDING OFF ON ANY ADVISORIES SINCE TEMPERATURES COULD BE
BORDERLINE AND NEXT SET OF GUIDANCE CAN BE CONSULTED AND STILL GET
LEAD TIME ON AN ADVISORY IF IT NEEDS TO BE ISSUED THIS
AFTERNOON...BUT AGAIN JUST FOR PARTS OF NORTHERN HERKIMER AND
HAMILTON COUNTIES. LOWS TONIGHT IN THE 30S.
STRONGER UPPER ENERGY...FORCING AND MOISTURE ADVECTION APPROACHES
SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON. RAIN SHOULD SPREAD
ACROSS THE REGION SATURDAY AFTERNOON AND NIGHT...AND BE HEAVY AT
TIMES SATURDAY NIGHT THROUGH SUNDAY. THERE ARE CONSIDERABLE
DISAGREEMENTS IN SOURCES OF GUIDANCE AND ENSEMBLES AS TO HOW MUCH
COLDER AIR SINKS SOUTH SATURDAY NIGHT IN RESPONSE TO ENHANCED UPPER
CONFLUENCE IN CANADA AS UPPER ENERGY TRACKS WELL NORTH OF THE U.S.
CANADIAN BORDER. BASED ON THE SOURCES OF GUIDANCE THAT RESOLVE
THESE ISSUES BEST...SIDING ON SOME COLD AIR DRAINING SOUTH IN
RESPONSE TO ENHANCED AGEOSTROPHIC NORTHERLY LOW LEVEL FLOW...
RESULTING IN SOME POTENTIAL FREEZING RAIN FOR THE SOUTHERN
ADIRONDACKS TO THE LAKE GEORGE AREA. WE WILL SEE HOW THE SNOW PACK
ACROSS THE ENTIRE REGION INFLUENCES SURFACE TEMPERATURES THROUGH
SATURDAY NIGHT AS WELL. WITH SUCH HIGH UNCERTAINTIES IN THE
RAIN/FREEZING RAIN LINE...NO HEADLINES YET UNTIL WE GET CLOSER TO
THE POTENTIAL EVENT. WHATEVER AREAS GET FREEZING RAIN COULD GET UP
TO A QUARTER INCH.
A VERY STRONG BOUNDARY LAYER JET SEGMENT AND ISENTROPIC LIFT...
ALONG WITH ANOMALOUSLY HIGH PWAT...SHOULD SUPPORT A HEAVY
RAIN EVENT...AND COMBINED WITH SNOW MELT...COULD RESULT IN SOME
FLOODING POTENTIAL. THIS WILL BE ADDRESSED IN THE HWO AS RAINFALL
FORECASTS FROM SOURCES OF GUIDANCE AND ENSEMBLES STILL A BROAD
RANGE AND AXIS OF HEAVIEST RAIN COULD FALL NORTH OF WHERE MAXIMUM
SNOW MELT OCCURS. A WEST TO SOUTHWEST BOUNDARY LAYER FLOW USUALLY
RESULTS IN THE HEAVIEST PRECIPITATION IN THE ADIRONDACKS...WHICH
AGAIN MAY SEE THE LEAST WARM TEMPERATURES AND LEAST SNOW MELT.
SO...STILL HOLDING OFF ON ANY FLOOD WATCHES.
HIGHS SATURDAY IN THE 40S TO AROUND 50...WITH LOWS SATURDAY NIGHT
AROUND 40 TO THE MID 40S...LOWER TO MID 30S IN THE NORTH COUNTRY.
HIGHS SUNDAY IN THE 50S MANY AREAS...BUT INTO THE 60S TOWARD POU
AND NW CT...AND IN THE 40S IN THE NORTH COUNTRY. THE COLD
FRONT TRACKS THROUGH THE REGION SUNDAY NIGHT AND SHOWERS SHOULD
CHANGE TO SNOW SHOWERS AS COLD AIR SPREADS ACROSS THE REGION.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
HAVE GENERALLY POPULATED THIS PORTION OF THE GRIDDED DATABASE WITH
00Z/20 HPC GUIDANCE.
MON-TUE...THE COLD FRONT ASSOCIATED WITH THIS WEEKEND/S STORM SYSTEM
SHOULD BE EXITING THE REGION MON AM...WITH RAIN SHOWERS TAPERING
OFF...BUT PROBABLY CHANGING TO SNOW SHOWERS BEFORE ENDING FOR AREAS
N AND W OF ALBANY. IN THE WAKE OF THE SFC FRONT...THE UPPER LEVEL
TROUGH WILL GRADUALLY TRANSLATE EASTWARD...PASSING ACROSS THE REGION
LATE MON NT OR ON TUE. THE COMBINATION OF THE ASSOCIATED COLD
POOL...AND COLDER AIR POURING ACROSS THE GREAT LAKES WILL LIKELY
LEAD TO AT LEAST SCATTERED SNOW SHOWERS AND FLURRIES FROM LATE
MONDAY INTO TUESDAY...ALONG WITH THE POSSIBILITY OF SOME LAKE EFFECT
SNOWBANDS SOMEWHERE ACROSS THE WESTERN ADIRONDACKS AND/OR MOHAWK
VALLEY...WHICH COULD OCCASIONALLY EXTEND INTO THE CAPITAL REGION AND
BERKSHIRES/SOUTHERN GREEN MTNS. AS FOR TEMPS...EXPECT MAXES TO REACH
THE 30S TO LOWER 40S MON IN VALLEY AREAS...AND 20S TO LOWER 30S
ACROSS HIGHER ELEVATIONS...WITH MOST MAX TEMPS LIKELY OCCURRING IN
THE MORNING WITH FALLING AFTERNOON TEMPS. FOR MON NT...EXPECT TEMPS
TO FALL INTO THE SINGLE DIGITS AND TEENS ACROSS NORTHERN AREAS...AND
TEENS AND LOWER/MID 20S FOR CENTRAL AND SOUTHERN AREAS. ON
TUE...EXPECT MAX TEMPS TO ONLY REACH THE SINGLE DIGITS AND LOWER
TEENS ACROSS MUCH OF THE SOUTHERN ADIRONDACKS...WITH MAINLY 20S FOR
VALLEY AREAS.
TUE NT-WED NT...HIGH PRESSURE WILL THEN BUILD IN FOR TUE
NT-WED...WHILE A WEAK CLIPPER TYPE SYSTEM PASSES BY TO OUR N AND W
WED NT. HAVE INCLUDED SOME SLIGHT CHC POPS FOR WED NT ACROSS
PORTIONS OF THE WESTERN ADIRONDACKS. AS FOR TEMPS...EXPECT TUE
NT/WED AM MINS TO FALL INTO THE SINGLE DIGITS AND TEENS IN MOST
AREAS...WITH SOME READINGS POSSIBLY FALLING TO BETWEEN ZERO AND 5
BELOW ACROSS PORTIONS OF THE SOUTHERN ADIRONDACKS. ON WED...EXPECT
MAX TEMPS TO REACH 25-30 IN VALLEY AREAS...AND UPPER TEENS TO LOWER
20S ACROSS HIGHER ELEVATIONS. FOR WED NT/THU AM...EXPECT MINS TO
FALL INTO THE TEENS AND 20S IN MOST AREAS.
THU...THE 00Z/20 ECMWF CONTINUES TO HINT AT A WEAK COASTAL SYSTEM
OFF THE SE COAST POTENTIALLY PHASING WITH SOME ENERGY ACROSS THE
GREAT LAKES TO ALLOW FOR LIGHT PRECIPITATION TO DEVELOP ACROSS THE
REGION. ALTHOUGH THE DETERMINISTIC 00Z/20 GFS IS NOT QUITE AS
EMPHATIC WITH THIS PHASING...SOME MEMBERS OF THE 00Z/20 GEFS DO
INDEED DEPICT SOME FORM OF THIS...WITH SOME SIGNAL NOTED IN THE MEAN
GEFS. WILL THEREFORE INDICATE CHC POPS...MAINLY FOR SNOW ON
THU...WITH PERHAPS A RAIN/SNOW MIX FOR SOUTHERN AREAS. AS FOR
TEMPS...HAVE INDICATED MAXES REACHING THE 35-40 IN MOST
VALLEYS...AND 25-30 FOR HIGHER ELEVATIONS.
&&
.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
LIGHT RAIN TO IMPACT MAINLY THE NORTHERN TAFS THIS AFTERNOON
ALTHOUGH FOR THE MOST PART THE IMPACT SHOULD BE MARGINAL. WE DID
INCLUDE A 3-HR TEMPO 2SM BR (IFR) KPSF 19Z-22Z). OTHERWISE VFR
CIGS/VSBY WILL LIKELY TRANSITION TO MVFR AT THE REMAINING TAF
SITES...EXCEPT KPOU WHERE LESS IN THE WAY OF SHOWERS WILL MEAN A
CONTINUATION OF VFR INTO THE EVENING.
HOWEVER...AS HIGH DEWPOINTS WORK INTO THE REGION TONIGHT...EVERYONE
LOOKS TO DIP INTO THE MVFR THRESHOLD (LOW MVFR AT KALB) AND IFR
CONDITIONS AT KGFL...AFTER 00Z THIS EVENING. ONCE CONDITIONS
DROP...THEY MIGHT HANG AT THESE RESPECTIVE VALUES INTO AT LEAST
SATURDAY MORNING...POSSIBLY LONGER NORTH OF KPOU. A MILD BUT MOIST
SOUTHERLY FLOW WILL CONTINUE THROUGH THE PERIOD.
THE WIND WILL BE SOUTHERLY LESS THAN 10 KT THROUGH 12Z SATURDAY.
OUTLOOK...
SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA.
SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
MONDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN.
TUESDAY: LOW OPERATIONAL IMPACT.BREEZY ISOLATED SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
WARMER TEMPERATURES WILL HAPPEN FRIDAY INTO THE WEEKEND...WITH A
FRONTAL BOUNDARY BRINGING SOME SHOWERS AND MIXED PRECIPITATION TO
CLOSE THE WORK WEEK. SOME SNOW MELT IS LIKELY BY THIS WEEKEND.
ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING
SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH
EVEN MILDER TEMPS.
TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S OR POSSIBLY
EVEN 60S ACROSS THE EASTERN CATSKILLS...MID HUDSON VALLEY...CENTRAL
AND SOUTHERN TACONICS INTO THE BERKSHIRES AND ACROSS LITCHFIELD
COUNTY WITH 50S ACROSS THE CAPITAL REGION...40S FURTHER NORTH.
BETWEEN THE RAIN AND RUNOFF FROM SNOWMELT DUE TO THE MILD/WARM
TEMPERATURES SOME FLOODING COULD BE A PROBLEM INCLUDING ICE JAMS
ISSUES. AT THIS POINT...WE BELIEVE MOST IF NOT ALL OF THE SNOW COULD
BE MELTED FROM ABOUT THE MOHAWK RIVER...FURTHER NORTH TEMPERATURES
MIGHT NOT BE WARM ENOUGH TO MELT ALL OF THE SNOW.
THE POTENTIAL IS THERE FOR 1-2 INCHES OF RAINFALL FROM ALBANY
NORTHWARD...POSSIBLY SOME AREAS REACHING 3 INCHES. LESS AMOUNTS OF
RAIN LOOK TO FALL SOUTH OF THE CAPITAL REGION...AN INCH OR LESS.
WILL KEEP MENTION OF IN OUR HAZARDOUS WEATHER OUTLOOK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...HWJIV/NAS
NEAR TERM...HWJIV/NAS
SHORT TERM...NAS
LONG TERM...KL
AVIATION...HWJIV
HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS ALBANY NY
110 PM EST FRI DEC 20 2013
.SYNOPSIS...
WAVES OF LOW PRESSURE WILL TRACK ALONG A NEARLY STATIONARY FRONT
FROM THE GREAT LAKES THROUGH NORTHERN NEW YORK AND NORTHERN NEW
ENGLAND THROUGH TONIGHT. THE FRONT WILL SINK SOUTH AS A COLD FRONT
INTO PARTS OF CENTRAL NEW YORK AND SOUTHERN VERMONT SATURDAY
NIGHT...SUPPORTING CHANCES FOR FREEZING RAIN IN THE NORTH COUNTRY.
STRONG LOW PRESSURE WILL TRACK NORTHEAST OUT OF THE TENNESSEE AND
OHIO VALLEY SUNDAY AS THE FRONT SURGES NORTH INTO CANADA...
BRINGING LOCALLY HEAVY RAIN AND WARMER TEMPERATURES TO OUR REGION.
A COLD FRONT WILL TRACK THROUGH OUR AREA SUNDAY NIGHT AND MONDAY
MORNING BRINGING A RETURN TO COLDER WEATHER FOR THE BEGINNING OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1245 PM...RADAR INDICATED FAIRLY WIDESPREAD LIGHT RAIN
OCCURRING OR WILL SHORTLY SPREAD INTO THE NORTHERN THREE-FOURTHS OF
THE FORECAST AREA. HAVE ADJUSTED POPS UPWARD TO LIKELY AND
CATEGORICAL IN THESE AREAS AND INCREASED POPS OVER THE FAR SOUTH TO
SLIGHT OR LOW CHANCE. TEMPS IN THE ADIRONDACK ZONES GENERALLY IN THE
MID OR UPPER 30S SO NO THREAT FOR ANY FREEZING RAIN FOR THE REST OF
TODAY. HAVE ADJUSTED TEMPS HIGHER...ESPECIALLY ACROSS THE HIGHER
TERRAIN WHERE THE WOUTHWEST FLOW HAS SCOURED OUT ANY REMAINING
COLDER AIR. TEMPS OVER THE HIGHER TERRAIN OF THE CATSKILLS ARE
CURRENTLY AROUND 50.
.PREVIOUS DISCUSSION...
AS OF 930 AM EST...RADARS INDICATING SOME LIGHT SPOTTY RETURNS
ACROSS MAINLY OUR NORTHERN AREAS. THE HRRR LOOKS ON CUE...WITH
LIGHTLY PRECIPITATION LIKELY TO FILL IN AS THE AFTERNOON
ARRIVES...DUE TO INCREASED CONVERGENCE AND MOISTURE ALONG AN
APPROACHING BOUNDARY.
TEMPERATURES IN THE VALLEYS GENERALLY IN THE 30S ABOVE FREEZING.
HOWEVER...MESO SITES INDICATED TEMPERATURES INTO THE 40S ACROSS
MAINLY THE HIGHER ELEVATIONS OF CATSKILLS...BUT EVEN ABOVE FREEZING
ACROSS OUR SOUTHERN ADIRONDACKS. SNOW MELT HAS COMMENCE...AND MANY
AREAS WILL LIKELY NOT DROP BACK BELOW FREEZING UNTIL SUNDAY NIGHT.
NO REAL CHANGES WITH THIS PACKAGE...TWEAKED THE POPS (DOWNWARD A
LITTLE IN THE BEGINNING GRIDS) AND OF COURSE RE-TOOLED THE HOURLY
GRIDS. LOOK FOR LOTS OF CLOUDS TODAY...AND AN INCREASING CHANCE OF
MAINLY RAIN SHOWERS THIS AFTERNOON (WITH PERHAPS SOME POCKETS OF
FREEZING RAIN UP NORTH)...MAINLY ALBANY NORTH.
HIGH TEMPERATURES THIS AFTERNOON REACHING 45-50 SOUTH OF CAPITAL
DISTRICT...40-45 CAPITAL DISTRICT AND SURROUNDING PARTS. TO THE
NORTH...HIGHS WILL GENERALLY BE 35-40.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
ONE WEAK UPPER IMPULSE AND WEAK FORCING AFFECTS OUR REGION THIS
AFTERNOON AND TONIGHT. THE BEST COVERAGE OF PRECIPITATION TONIGHT
SHOULD BE NORTH OF THE MOHAWK VALLEY AND WEST OF THE LAKE GEORGE
SARATOGA REGION. HOWEVER...SOLID CHANCES FROM SCHOHARIE VALLEY
THROUGH THE CAPITAL DISTRICT...SOUTHERN VT INTO THE BERKSHIRES AND
EASTERN CATSKILLS. PRECIPITATION AMOUNTS SHOULD BE LIGHT...BUT
NIGHTTIME COOLING IN THE SOUTHERN ADIRONDACKS COULD ALLOW SOME OF
THE PRECIPITATION TO FALL AS FREEZING RAIN...MAYBE UP TO A TENTH
OF AN INCH. HOLDING OFF ON ANY ADVISORIES SINCE TEMPERATURES COULD BE
BORDERLINE AND NEXT SET OF GUIDANCE CAN BE CONSULTED AND STILL GET
LEAD TIME ON AN ADVISORY IF IT NEEDS TO BE ISSUED THIS
AFTERNOON...BUT AGAIN JUST FOR PARTS OF NORTHERN HERKIMER AND
HAMILTON COUNTIES. LOWS TONIGHT IN THE 30S.
STRONGER UPPER ENERGY...FORCING AND MOISTURE ADVECTION APPROACHES
SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON. RAIN SHOULD SPREAD
ACROSS THE REGION SATURDAY AFTERNOON AND NIGHT...AND BE HEAVY AT
TIMES SATURDAY NIGHT THROUGH SUNDAY. THERE ARE CONSIDERABLE
DISAGREEMENTS IN SOURCES OF GUIDANCE AND ENSEMBLES AS TO HOW MUCH
COLDER AIR SINKS SOUTH SATURDAY NIGHT IN RESPONSE TO ENHANCED UPPER
CONFLUENCE IN CANADA AS UPPER ENERGY TRACKS WELL NORTH OF THE U.S.
CANADIAN BORDER. BASED ON THE SOURCES OF GUIDANCE THAT RESOLVE
THESE ISSUES BEST...SIDING ON SOME COLD AIR DRAINING SOUTH IN
RESPONSE TO ENHANCED AGEOSTROPHIC NORTHERLY LOW LEVEL FLOW...
RESULTING IN SOME POTENTIAL FREEZING RAIN FOR THE SOUTHERN
ADIRONDACKS TO THE LAKE GEORGE AREA. WE WILL SEE HOW THE SNOW PACK
ACROSS THE ENTIRE REGION INFLUENCES SURFACE TEMPERATURES THROUGH
SATURDAY NIGHT AS WELL. WITH SUCH HIGH UNCERTAINTIES IN THE
RAIN/FREEZING RAIN LINE...NO HEADLINES YET UNTIL WE GET CLOSER TO
THE POTENTIAL EVENT. WHATEVER AREAS GET FREEZING RAIN COULD GET UP
TO A QUARTER INCH.
A VERY STRONG BOUNDARY LAYER JET SEGMENT AND ISENTROPIC LIFT...
ALONG WITH ANOMALOUSLY HIGH PWAT...SHOULD SUPPORT A HEAVY
RAIN EVENT...AND COMBINED WITH SNOW MELT...COULD RESULT IN SOME
FLOODING POTENTIAL. THIS WILL BE ADDRESSED IN THE HWO AS RAINFALL
FORECASTS FROM SOURCES OF GUIDANCE AND ENSEMBLES STILL A BROAD
RANGE AND AXIS OF HEAVIEST RAIN COULD FALL NORTH OF WHERE MAXIMUM
SNOW MELT OCCURS. A WEST TO SOUTHWEST BOUNDARY LAYER FLOW USUALLY
RESULTS IN THE HEAVIEST PRECIPITATION IN THE ADIRONDACKS...WHICH
AGAIN MAY SEE THE LEAST WARM TEMPERATURES AND LEAST SNOW MELT.
SO...STILL HOLDING OFF ON ANY FLOOD WATCHES.
HIGHS SATURDAY IN THE 40S TO AROUND 50...WITH LOWS SATURDAY NIGHT
AROUND 40 TO THE MID 40S...LOWER TO MID 30S IN THE NORTH COUNTRY.
HIGHS SUNDAY IN THE 50S MANY AREAS...BUT INTO THE 60S TOWARD POU
AND NW CT...AND IN THE 40S IN THE NORTH COUNTRY. THE COLD
FRONT TRACKS THROUGH THE REGION SUNDAY NIGHT AND SHOWERS SHOULD
CHANGE TO SNOW SHOWERS AS COLD AIR SPREADS ACROSS THE REGION.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
HAVE GENERALLY POPULATED THIS PORTION OF THE GRIDDED DATABASE WITH
00Z/20 HPC GUIDANCE.
MON-TUE...THE COLD FRONT ASSOCIATED WITH THIS WEEKEND/S STORM SYSTEM
SHOULD BE EXITING THE REGION MON AM...WITH RAIN SHOWERS TAPERING
OFF...BUT PROBABLY CHANGING TO SNOW SHOWERS BEFORE ENDING FOR AREAS
N AND W OF ALBANY. IN THE WAKE OF THE SFC FRONT...THE UPPER LEVEL
TROUGH WILL GRADUALLY TRANSLATE EASTWARD...PASSING ACROSS THE REGION
LATE MON NT OR ON TUE. THE COMBINATION OF THE ASSOCIATED COLD
POOL...AND COLDER AIR POURING ACROSS THE GREAT LAKES WILL LIKELY
LEAD TO AT LEAST SCATTERED SNOW SHOWERS AND FLURRIES FROM LATE
MONDAY INTO TUESDAY...ALONG WITH THE POSSIBILITY OF SOME LAKE EFFECT
SNOWBANDS SOMEWHERE ACROSS THE WESTERN ADIRONDACKS AND/OR MOHAWK
VALLEY...WHICH COULD OCCASIONALLY EXTEND INTO THE CAPITAL REGION AND
BERKSHIRES/SOUTHERN GREEN MTNS. AS FOR TEMPS...EXPECT MAXES TO REACH
THE 30S TO LOWER 40S MON IN VALLEY AREAS...AND 20S TO LOWER 30S
ACROSS HIGHER ELEVATIONS...WITH MOST MAX TEMPS LIKELY OCCURRING IN
THE MORNING WITH FALLING AFTERNOON TEMPS. FOR MON NT...EXPECT TEMPS
TO FALL INTO THE SINGLE DIGITS AND TEENS ACROSS NORTHERN AREAS...AND
TEENS AND LOWER/MID 20S FOR CENTRAL AND SOUTHERN AREAS. ON
TUE...EXPECT MAX TEMPS TO ONLY REACH THE SINGLE DIGITS AND LOWER
TEENS ACROSS MUCH OF THE SOUTHERN ADIRONDACKS...WITH MAINLY 20S FOR
VALLEY AREAS.
TUE NT-WED NT...HIGH PRESSURE WILL THEN BUILD IN FOR TUE
NT-WED...WHILE A WEAK CLIPPER TYPE SYSTEM PASSES BY TO OUR N AND W
WED NT. HAVE INCLUDED SOME SLIGHT CHC POPS FOR WED NT ACROSS
PORTIONS OF THE WESTERN ADIRONDACKS. AS FOR TEMPS...EXPECT TUE
NT/WED AM MINS TO FALL INTO THE SINGLE DIGITS AND TEENS IN MOST
AREAS...WITH SOME READINGS POSSIBLY FALLING TO BETWEEN ZERO AND 5
BELOW ACROSS PORTIONS OF THE SOUTHERN ADIRONDACKS. ON WED...EXPECT
MAX TEMPS TO REACH 25-30 IN VALLEY AREAS...AND UPPER TEENS TO LOWER
20S ACROSS HIGHER ELEVATIONS. FOR WED NT/THU AM...EXPECT MINS TO
FALL INTO THE TEENS AND 20S IN MOST AREAS.
THU...THE 00Z/20 ECMWF CONTINUES TO HINT AT A WEAK COASTAL SYSTEM
OFF THE SE COAST POTENTIALLY PHASING WITH SOME ENERGY ACROSS THE
GREAT LAKES TO ALLOW FOR LIGHT PRECIPITATION TO DEVELOP ACROSS THE
REGION. ALTHOUGH THE DETERMINISTIC 00Z/20 GFS IS NOT QUITE AS
EMPHATIC WITH THIS PHASING...SOME MEMBERS OF THE 00Z/20 GEFS DO
INDEED DEPICT SOME FORM OF THIS...WITH SOME SIGNAL NOTED IN THE MEAN
GEFS. WILL THEREFORE INDICATE CHC POPS...MAINLY FOR SNOW ON
THU...WITH PERHAPS A RAIN/SNOW MIX FOR SOUTHERN AREAS. AS FOR
TEMPS...HAVE INDICATED MAXES REACHING THE 35-40 IN MOST
VALLEYS...AND 25-30 FOR HIGHER ELEVATIONS.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
MAINLY VFR LEVEL CLOUDS PERSIST ACROSS THE REGION...WITH BASES OF
3500-6000 FT AGL CONFINED MAINLY TO KGFL/KALB...WITH MUCH HIGHER
CIGS FURTHER SOUTH AND EAST. SOME SPRINKLES MAY OCCUR NEAR OR
NORTH OF KGFL OVER THE NEXT 2 HOURS.
THROUGH THE DAY...SKIES SHOULD REMAIN MOSTLY CLOUDY...BUT
INITIALLY CIGS SHOULD REMAIN VFR. HOWEVER...SOME AREAS OF LIGHT
RAIN SHOWERS WILL DEVELOP AROUND MIDDAY FOR KGFL/KPSF/KALB...WITH
CIGS GRADUALLY LOWERING INTO THE MVFR RANGE IN THESE AREAS. THE
SHOWERS SHOULD REMAIN NORTH OF KPOU...WHERE VFR CONDITIONS SHOULD
CONTINUE THROUGH THE DAY.
OCCASIONAL LIGHT RAIN OR DRIZZLE WILL CONTINUE OVERNIGHT FOR
KGFL/KALB AND KPSF...WHILE REMAINING GENERALLY NORTH OF KPOU.
CIGS/VSBYS WILL CONTINUE TO BE MAINLY MVFR AT
KGFL/KALB/KPSF...WITH SOME OCCASIONAL IFR CONDITIONS
POSSIBLE...ESP AFTER 05Z/SAT. AT KPOU...THE VSBY MAY LOWER INTO
THE MVFR RANGE LATER TONIGHT.
WINDS WILL BE SOUTHERLY LESS THAN 10 KT THROUGH 12Z SATURDAY.
OUTLOOK...
SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA.
SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
MONDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN.
TUESDAY: LOW OPERATIONAL IMPACT.BREEZY ISOLATED SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
WARMER TEMPERATURES WILL HAPPEN FRIDAY INTO THE WEEKEND...WITH A
FRONTAL BOUNDARY BRINGING SOME SHOWERS AND MIXED PRECIPITATION TO
CLOSE THE WORK WEEK. SOME SNOW MELT IS LIKELY BY THIS WEEKEND.
ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING
SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH
EVEN MILDER TEMPS.
TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S OR POSSIBLY
EVEN 60S ACROSS THE EASTERN CATSKILLS...MID HUDSON VALLEY...CENTRAL
AND SOUTHERN TACONICS INTO THE BERKSHIRES AND ACROSS LITCHFIELD
COUNTY WITH 50S ACROSS THE CAPITAL REGION...40S FURTHER NORTH.
BETWEEN THE RAIN AND RUNOFF FROM SNOWMELT DUE TO THE MILD/WARM
TEMPERATURES SOME FLOODING COULD BE A PROBLEM INCLUDING ICE JAMS
ISSUES. AT THIS POINT...WE BELIEVE MOST IF NOT ALL OF THE SNOW COULD
BE MELTED FROM ABOUT THE MOHAWK RIVER...FURTHER NORTH TEMPERATURES
MIGHT NOT BE WARM ENOUGH TO MELT ALL OF THE SNOW.
THE POTENTIAL IS THERE FOR 1-2 INCHES OF RAINFALL FROM ALBANY
NORTHWARD...POSSIBLY SOME AREAS REACHING 3 INCHES. LESS AMOUNTS OF
RAIN LOOK TO FALL SOUTH OF THE CAPITAL REGION...AN INCH OR LESS.
WILL KEEP MENTION OF IN OUR HAZARDOUS WEATHER OUTLOOK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...HWJIV/NAS
NEAR TERM...GJM/HWJIV
SHORT TERM...NAS
LONG TERM...KL
AVIATION...KL
HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS ALBANY NY
930 AM EST FRI DEC 20 2013
.SYNOPSIS...
WAVES OF LOW PRESSURE WILL TRACK ALONG A NEARLY STATIONARY FRONT
FROM THE GREAT LAKES THROUGH NORTHERN NEW YORK AND NORTHERN NEW
ENGLAND THROUGH TONIGHT. THE FRONT WILL SINK SOUTH AS A COLD FRONT
INTO PARTS OF CENTRAL NEW YORK AND SOUTHERN VERMONT SATURDAY
NIGHT...SUPPORTING CHANCES FOR FREEZING RAIN IN THE NORTH COUNTRY.
STRONG LOW PRESSURE WILL TRACK NORTHEAST OUT OF THE TENNESSEE AND
OHIO VALLEY SUNDAY AS THE FRONT SURGES NORTH INTO CANADA...
BRINGING LOCALLY HEAVY RAIN AND WARMER TEMPERATURES TO OUR REGION.
A COLD FRONT WILL TRACK THROUGH OUR AREA SUNDAY NIGHT AND MONDAY
MORNING BRINGING A RETURN TO COLDER WEATHER FOR THE BEGINNING OF
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 930 AM EST...RADARS INDICATING SOME LIGHT SPOTTY RETURNS
ACROSS MAINLY OUR NORTHERN AREAS. THE HRRR LOOKS ON CUE...WITH
LIGHTLY PRECIPITATION LIKELY TO FILL IN AS THE AFTERNOON
ARRIVES...DUE TO INCREASED CONVERGENCE AND MOISTURE ALONG AN
APPROACHING BOUNDARY.
TEMPERATURES IN THE VALLEYS GENERALLY IN THE 30S ABOVE FREEZING.
HOWEVER...MESO SITES INDICATED TEMPERATURES INTO THE 40S ACROSS
MAINLY THE HIGHER ELEVATIONS OF CATSKILLS...BUT EVEN ABOVE FREEZING
ACROSS OUR SOUTHERN ADIRONDACKS. SNOW MELT HAS COMMENCE...AND MANY
AREAS WILL LIKELY NOT DROP BACK BELOW FREEZING UNTIL SUNDAY NIGHT.
NO REAL CHANGES WITH THIS PACKAGE...TWEAKED THE POPS (DOWNWARD A
LITTLE IN THE BEGINNING GRIDS) AND OF COURSE RE-TOOLED THE HOURLY
GRIDS. LOOK FOR LOTS OF CLOUDS TODAY...AND AN INCREASING CHANCE OF
MAINLY RAIN SHOWERS THIS AFTERNOON (WITH PERHAPS SOME POCKETS OF
FREEZING RAIN UP NORTH)...MAINLY ALBANY NORTH.
HIGH TEMPERATURES THIS AFTERNOON REACHING 45-50 SOUTH OF CAPITAL
DISTRICT...40-45 CAPITAL DISTRICT AND SURROUNDING PARTS. TO THE
NORTH...HIGHS WILL GENERALLY BE 35-40.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/...
ONE WEAK UPPER IMPULSE AND WEAK FORCING AFFECTS OUR REGION THIS
AFTERNOON AND TONIGHT. THE BEST COVERAGE OF PRECIPITATION TONIGHT
SHOULD BE NORTH OF THE MOHAWK VALLEY AND WEST OF THE LAKE GEORGE
SARATOGA REGION. HOWEVER...SOLID CHANCES FROM SCHOHARIE VALLEY
THROUGH THE CAPITAL DISTRICT...SOUTHERN VT INTO THE BERKSHIRES AND
EASTERN CATSKILLS. PRECIPITATION AMOUNTS SHOULD BE LIGHT...BUT
NIGHTTIME COOLING IN THE SOUTHERN ADIRONDACKS COULD ALLOW SOME OF
THE PRECIPITATION TO FALL AS FREEZING RAIN...MAYBE UP TO A TENTH
OF AN INCH. HOLDING OFF ON ANY ADVISORIES SINCE TEMPERATURES COULD BE
BORDERLINE AND NEXT SET OF GUIDANCE CAN BE CONSULTED AND STILL GET
LEAD TIME ON AN ADVISORY IF IT NEEDS TO BE ISSUED THIS
AFTERNOON...BUT AGAIN JUST FOR PARTS OF NORTHERN HERKIMER AND
HAMILTON COUNTIES. LOWS TONIGHT IN THE 30S.
STRONGER UPPER ENERGY...FORCING AND MOISTURE ADVECTION APPROACHES
SATURDAY AFTERNOON THROUGH SUNDAY AFTERNOON. RAIN SHOULD SPREAD
ACROSS THE REGION SATURDAY AFTERNOON AND NIGHT...AND BE HEAVY AT
TIMES SATURDAY NIGHT THROUGH SUNDAY. THERE ARE CONSIDERABLE
DISAGREEMENTS IN SOURCES OF GUIDANCE AND ENSEMBLES AS TO HOW MUCH
COLDER AIR SINKS SOUTH SATURDAY NIGHT IN RESPONSE TO ENHANCED UPPER
CONFLUENCE IN CANADA AS UPPER ENERGY TRACKS WELL NORTH OF THE U.S.
CANADIAN BORDER. BASED ON THE SOURCES OF GUIDANCE THAT RESOLVE
THESE ISSUES BEST...SIDING ON SOME COLD AIR DRAINING SOUTH IN
RESPONSE TO ENHANCED AGEOSTROPHIC NORTHERLY LOW LEVEL FLOW...
RESULTING IN SOME POTENTIAL FREEZING RAIN FOR THE SOUTHERN
ADIRONDACKS TO THE LAKE GEORGE AREA. WE WILL SEE HOW THE SNOW PACK
ACROSS THE ENTIRE REGION INFLUENCES SURFACE TEMPERATURES THROUGH
SATURDAY NIGHT AS WELL. WITH SUCH HIGH UNCERTAINTIES IN THE
RAIN/FREEZING RAIN LINE...NO HEADLINES YET UNTIL WE GET CLOSER TO
THE POTENTIAL EVENT. WHATEVER AREAS GET FREEZING RAIN COULD GET UP
TO A QUARTER INCH.
A VERY STRONG BOUNDARY LAYER JET SEGMENT AND ISENTROPIC LIFT...
ALONG WITH ANOMALOUSLY HIGH PWAT...SHOULD SUPPORT A HEAVY
RAIN EVENT...AND COMBINED WITH SNOW MELT...COULD RESULT IN SOME
FLOODING POTENTIAL. THIS WILL BE ADDRESSED IN THE HWO AS RAINFALL
FORECASTS FROM SOURCES OF GUIDANCE AND ENSEMBLES STILL A BROAD
RANGE AND AXIS OF HEAVIEST RAIN COULD FALL NORTH OF WHERE MAXIMUM
SNOW MELT OCCURS. A WEST TO SOUTHWEST BOUNDARY LAYER FLOW USUALLY
RESULTS IN THE HEAVIEST PRECIPITATION IN THE ADIRONDACKS...WHICH
AGAIN MAY SEE THE LEAST WARM TEMPERATURES AND LEAST SNOW MELT.
SO...STILL HOLDING OFF ON ANY FLOOD WATCHES.
HIGHS SATURDAY IN THE 40S TO AROUND 50...WITH LOWS SATURDAY NIGHT
AROUND 40 TO THE MID 40S...LOWER TO MID 30S IN THE NORTH COUNTRY.
HIGHS SUNDAY IN THE 50S MANY AREAS...BUT INTO THE 60S TOWARD POU
AND NW CT...AND IN THE 40S IN THE NORTH COUNTRY. THE COLD
FRONT TRACKS THROUGH THE REGION SUNDAY NIGHT AND SHOWERS SHOULD
CHANGE TO SNOW SHOWERS AS COLD AIR SPREADS ACROSS THE REGION.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
HAVE GENERALLY POPULATED THIS PORTION OF THE GRIDDED DATABASE WITH
00Z/20 HPC GUIDANCE.
MON-TUE...THE COLD FRONT ASSOCIATED WITH THIS WEEKEND/S STORM SYSTEM
SHOULD BE EXITING THE REGION MON AM...WITH RAIN SHOWERS TAPERING
OFF...BUT PROBABLY CHANGING TO SNOW SHOWERS BEFORE ENDING FOR AREAS
N AND W OF ALBANY. IN THE WAKE OF THE SFC FRONT...THE UPPER LEVEL
TROUGH WILL GRADUALLY TRANSLATE EASTWARD...PASSING ACROSS THE REGION
LATE MON NT OR ON TUE. THE COMBINATION OF THE ASSOCIATED COLD
POOL...AND COLDER AIR POURING ACROSS THE GREAT LAKES WILL LIKELY
LEAD TO AT LEAST SCATTERED SNOW SHOWERS AND FLURRIES FROM LATE
MONDAY INTO TUESDAY...ALONG WITH THE POSSIBILITY OF SOME LAKE EFFECT
SNOWBANDS SOMEWHERE ACROSS THE WESTERN ADIRONDACKS AND/OR MOHAWK
VALLEY...WHICH COULD OCCASIONALLY EXTEND INTO THE CAPITAL REGION AND
BERKSHIRES/SOUTHERN GREEN MTNS. AS FOR TEMPS...EXPECT MAXES TO REACH
THE 30S TO LOWER 40S MON IN VALLEY AREAS...AND 20S TO LOWER 30S
ACROSS HIGHER ELEVATIONS...WITH MOST MAX TEMPS LIKELY OCCURRING IN
THE MORNING WITH FALLING AFTERNOON TEMPS. FOR MON NT...EXPECT TEMPS
TO FALL INTO THE SINGLE DIGITS AND TEENS ACROSS NORTHERN AREAS...AND
TEENS AND LOWER/MID 20S FOR CENTRAL AND SOUTHERN AREAS. ON
TUE...EXPECT MAX TEMPS TO ONLY REACH THE SINGLE DIGITS AND LOWER
TEENS ACROSS MUCH OF THE SOUTHERN ADIRONDACKS...WITH MAINLY 20S FOR
VALLEY AREAS.
TUE NT-WED NT...HIGH PRESSURE WILL THEN BUILD IN FOR TUE
NT-WED...WHILE A WEAK CLIPPER TYPE SYSTEM PASSES BY TO OUR N AND W
WED NT. HAVE INCLUDED SOME SLIGHT CHC POPS FOR WED NT ACROSS
PORTIONS OF THE WESTERN ADIRONDACKS. AS FOR TEMPS...EXPECT TUE
NT/WED AM MINS TO FALL INTO THE SINGLE DIGITS AND TEENS IN MOST
AREAS...WITH SOME READINGS POSSIBLY FALLING TO BETWEEN ZERO AND 5
BELOW ACROSS PORTIONS OF THE SOUTHERN ADIRONDACKS. ON WED...EXPECT
MAX TEMPS TO REACH 25-30 IN VALLEY AREAS...AND UPPER TEENS TO LOWER
20S ACROSS HIGHER ELEVATIONS. FOR WED NT/THU AM...EXPECT MINS TO
FALL INTO THE TEENS AND 20S IN MOST AREAS.
THU...THE 00Z/20 ECMWF CONTINUES TO HINT AT A WEAK COASTAL SYSTEM
OFF THE SE COAST POTENTIALLY PHASING WITH SOME ENERGY ACROSS THE
GREAT LAKES TO ALLOW FOR LIGHT PRECIPITATION TO DEVELOP ACROSS THE
REGION. ALTHOUGH THE DETERMINISTIC 00Z/20 GFS IS NOT QUITE AS
EMPHATIC WITH THIS PHASING...SOME MEMBERS OF THE 00Z/20 GEFS DO
INDEED DEPICT SOME FORM OF THIS...WITH SOME SIGNAL NOTED IN THE MEAN
GEFS. WILL THEREFORE INDICATE CHC POPS...MAINLY FOR SNOW ON
THU...WITH PERHAPS A RAIN/SNOW MIX FOR SOUTHERN AREAS. AS FOR
TEMPS...HAVE INDICATED MAXES REACHING THE 35-40 IN MOST
VALLEYS...AND 25-30 FOR HIGHER ELEVATIONS.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
MAINLY VFR LEVEL CLOUDS PERSIST ACROSS THE REGION...WITH BASES OF
3500-6000 FT AGL CONFINED MAINLY TO KGFL/KALB...WITH MUCH HIGHER
CIGS FURTHER SOUTH AND EAST. SOME SPRINKLES MAY OCCUR NEAR OR
NORTH OF KGFL OVER THE NEXT 2 HOURS.
THROUGH THE DAY...SKIES SHOULD REMAIN MOSTLY CLOUDY...BUT
INITIALLY CIGS SHOULD REMAIN VFR. HOWEVER...SOME AREAS OF LIGHT
RAIN SHOWERS WILL DEVELOP AROUND MIDDAY FOR KGFL/KPSF/KALB...WITH
CIGS GRADUALLY LOWERING INTO THE MVFR RANGE IN THESE AREAS. THE
SHOWERS SHOULD REMAIN NORTH OF KPOU...WHERE VFR CONDITIONS SHOULD
CONTINUE THROUGH THE DAY.
OCCASIONAL LIGHT RAIN OR DRIZZLE WILL CONTINUE OVERNIGHT FOR
KGFL/KALB AND KPSF...WHILE REMAINING GENERALLY NORTH OF KPOU.
CIGS/VSBYS WILL CONTINUE TO BE MAINLY MVFR AT
KGFL/KALB/KPSF...WITH SOME OCCASIONAL IFR CONDITIONS
POSSIBLE...ESP AFTER 05Z/SAT. AT KPOU...THE VSBY MAY LOWER INTO
THE MVFR RANGE LATER TONIGHT.
WINDS WILL BE SOUTHERLY LESS THAN 10 KT THROUGH 12Z SATURDAY.
OUTLOOK...
SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE RA.
SUNDAY: HIGH OPERATIONAL IMPACT. LIKELY RA.
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
MONDAY: MODERATE OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA...SHSN.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. SCATTERED SHSN.
TUESDAY: LOW OPERATIONAL IMPACT.BREEZY ISOLATED SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
WARMER TEMPERATURES WILL HAPPEN FRIDAY INTO THE WEEKEND...WITH A
FRONTAL BOUNDARY BRINGING SOME SHOWERS AND MIXED PRECIPITATION TO
CLOSE THE WORK WEEK. SOME SNOW MELT IS LIKELY BY THIS WEEKEND.
ALSO...A STORM SYSTEM MOVING ALONG A FRONTAL BOUNDARY MAY BRING
SIGNIFICANT PCPN TO THE FORECAST AREA SAT NIGHT INTO SUNDAY WITH
EVEN MILDER TEMPS.
TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S OR POSSIBLY
EVEN 60S ACROSS THE EASTERN CATSKILLS...MID HUDSON VALLEY...CENTRAL
AND SOUTHERN TACONICS INTO THE BERKSHIRES AND ACROSS LITCHFIELD
COUNTY WITH 50S ACROSS THE CAPITAL REGION...40S FURTHER NORTH.
BETWEEN THE RAIN AND RUNOFF FROM SNOWMELT DUE TO THE MILD/WARM
TEMPERATURES SOME FLOODING COULD BE A PROBLEM INCLUDING ICE JAMS
ISSUES. AT THIS POINT...WE BELIEVE MOST IF NOT ALL OF THE SNOW COULD
BE MELTED FROM ABOUT THE MOHAWK RIVER...FURTHER NORTH TEMPERATURES
MIGHT NOT BE WARM ENOUGH TO MELT ALL OF THE SNOW.
THE POTENTIAL IS THERE FOR 1-2 INCHES OF RAINFALL FROM ALBANY
NORTHWARD...POSSIBLY SOME AREAS REACHING 3 INCHES. LESS AMOUNTS OF
RAIN LOOK TO FALL SOUTH OF THE CAPITAL REGION...AN INCH OR LESS.
WILL KEEP MENTION OF IN OUR HAZARDOUS WEATHER OUTLOOK.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...HWJIV/NAS
NEAR TERM...HWJIV
SHORT TERM...NAS
LONG TERM...KL
AVIATION...KL
HYDROLOGY...NAS
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
205 PM EST FRI DEC 20 2013
...NEAR RECORD HIGH TEMPERATURES THIS WEEKEND...
...WINTER OFFICIALLY BEGINS JUST AFTER NOON EST ON SATURDAY...
.SYNOPSIS...
19Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFYING UPPER LEVEL
PATTERN OVER THE CONUS. LONGWAVE TROUGHING NOW COVERS THE NATION TO
THE WEST OF THE CONTINENTAL DIVIDE...AND IS HIGHLIGHTED BY A POTENT
SHORTWAVE/CLOSED LOW FEATURE EJECTING EASTWARD OVER THE SW STATES
AND NORTHERN MEXICO. THE ADVANCEMENT OF THIS WESTERN TROUGH AND
ASSOCIATED HEIGHT FALLS HAVE HELPED TO "RIDGE UP" THE DOWNSTREAM
FLOW FROM THE EASTERN GULF OF MEXICO TO THE MID-ATLANTIC STATES.
THIS RIDGE OVER OUR HEADS WILL BE OUR PROTECTOR THROUGH THE UPCOMING
WEEKEND AND PROVIDE A GENERALLY FAIR AND UNSEASONABLY WARM FORECAST.
WV IMAGERY SHOWS SOUTHERN STREAM MOISTURE RAPIDLY ADVECTING
NORTHWARD ACROSS THE SOUTHERN PLAINS AHEAD OF THE STRONG SOUTHWEST
SHORTWAVE. THIS MOISTURE RETURN IS THE FIRST STAGE IN THE PRIMING OF
THE ATMOSPHERE FOR A POTENTIALLY SIGNIFICANT SEVERE WEATHER OUTBREAK
ACROSS THE LOWER MS VALLEY DURING SATURDAY. HOWEVER...AS MENTIONED
ABOVE THIS INCLEMENT WEATHER IS NOT IN OUR FORECAST WITH THE UPPER
RIDGE IN PLACE. 20/12Z KTBW SOUNDING...ALTHOUGH STILL ON THE DRY
SIDE...SHOWS THAT WE HAVE SEEN SOME MOISTURE RETURN THROUGH THE
COLUMN DURING THE PAST 24 HOURS...WITH THE PW VALUE JUMPING FROM
0.27" ON THURSDAY MORNING TO AROUND AN INCH THIS MORNING. MUCH OF
THIS MOISTURE RETURN HAS BEEN IN THE LOWER LEVELS BELOW A WELL
DEFINED SUBSIDENCE INVERSION (ASSOCIATED WITH THE UPPER RIDGING)
JUST ABOVE 700MB.
AT THE SURFACE...HIGH PRESSURE RIDGES BACK FROM THE WESTERN ATLANTIC
TO THE GA/CAROLINA COAST...PLACING OUR REGION WITHIN A LIGHT
SOUTHEAST FLOW REGIME. THIS FLOW HAS BEEN ADVECTING INCREASING
LEVELS OF BOUNDARY LAYER MOISTURE ACROSS THE PENINSULA...AND THESE
MOISTURE LEVELS WILL ONLY CONTINUE TO INCREASE THROUGH THE NEXT 24
HOURS. TEMPERATURES ARE APPROACHING OR SURPASSING 80 DEGREES AT MOST
STATIONS THIS MID-AFTERNOON.
&&
.SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)...
TONIGHT...A WARM AND FAIR OVERNIGHT PERIOD. THE CONTINUED MOISTURE
ADVECTION WITHIN THE LIGHT SE FLOW REGIME WILL PREVENT LOW TEMPS
FROM DROPPING OUT OF THE 60S FOR JUST ABOUT ALL AREAS. BOUNDARY
LAYER MOISTURE UNDERNEATH THE SUPPRESSION ALOFT DOES SET UP A
FAVORABLE SCENARIO FOR PATCHY/AREAS OF FOG DURING THE LATE NIGHT
HOURS. A WIDESPREAD DENSE FOG EVENT IS UNLIKELY...BUT LOCALIZED
AREAS OF REDUCED VISIBILITY ARE A GOOD BET FOR ANYONE DOING EARLY
TRAVELING SATURDAY MORNING. BOTH STATISTICAL MOS AND ENSEMBLE SREF
PROBS SUGGEST THIS FOG POTENTIAL.
SATURDAY...UNSEASONABLY WARM TEMPERATURES TO START OUT THE WEEKEND
UNDER AN UPPER RIDGE CHARACTERIZED BY H5 HEIGHTS OF 1.5-2 STANDARD
DEVIATIONS ABOVE CLIMO. GRADIENT WILL INCREASE SOMEWHAT AND SHOULD
HELP PREVENT MUCH IF ANY SEABREEZE DEVELOPMENT...OR AT LEAST INLAND
PENETRATION...DESPITE THE STRONG TERRESTRIAL HEATING. THEREFORE...
HAVE A RAIN FREE DAY IN THE FORECAST. THE STRONGER GRADIENT WILL
RESULT IN EVEN MORE EFFICIENT DIURNAL MIXING WITHIN A VERY WARM
POTENTIAL COLUMN WITH 850MB TEMPS AROUND 16C. THESE 850MB TEMPS ARE
ALSO 1.5-2 STANDARD DEVIATIONS ABOVE CLIMO. COMBINE ALL THIS AND WE
ARE LOOKING AT NEAR RECORD TEMPERATURES FOR THE WINTER SOLSTICE...
WITH LOWER 80S FAR NORTH AND WIDESPREAD MIDDLE 80S ELSEWHERE. BELOW
IS A SELECT LISTING OF SOME OF THE RECORD TEMPERATURES FOR DEC 21ST
ACROSS THE AREA:
BROOKSVILLE...86
FORT MYERS....87
LAKELAND......82
SARASOTA......86
PUNTA GORDA...84
ST PETERSBURG.82
TAMPA INTL....85
WINTER HAVEN..85
SUNDAY...
THE SYNOPTIC PATTERN OVER THE FLORIDA PENINSULA DOES NOT CHANGE MUCH
ON SUNDAY WITH THE MID/UPPER LEVEL RIDGE CONTINUING TO PROTECT THE
REGION FROM THE STORM SYSTEM TO OUR NORTHWEST. IT WILL NOT BE UNTIL
LATER SUNDAY NIGHT INTO MONDAY THAT THE RIDGE BEGINS TO BREAK DOWN
AND ALLOW A COLD FRONT TO FINALLY APPROACH. ONCE AGAIN LOOKING FOR
AREAS OF FOG TO BE AROUND THE REGION LATE SATURDAY NIGHT INTO EARLY
SUNDAY MORNING. ONCE THIS FOG AND LOWER CLOUDS BURN OFF...EXPECT A
MIX OF SUN AND CLOUDS AND NEAR RECORD TEMPERATURES REACHING THE
LOWER TO MIDDLE 80S ALMOST REGION-WIDE. A SLIGHTLY WEAKER GRADIENT
MAY ALLOW AN ONSHORE COMPONENT OF WIND TO DEVELOP NEAR THE COAST
DURING THE AFTERNOON WHICH WOULD ONLY SERVE TO KNOCK TEMPS AT THE
BEACHES BACK INTO THE 70S.
&&
.LONG TERM (MONDAY THROUGH NEXT THURSDAY)...
NO SIGNIFICANT CHANGES TO THE EXTENDED FORECAST AS THE UPPER
DISTURBANCE CENTERED OVER SOUTHERN CALIFORNIA EARLY THIS MORNING IS
FORECAST TO PROPAGATE TO THE EAST TODAY AND BECOME NEGATIVELY TILTED
OVER TEXAS AND OKLAHOMA ON SATURDAY BEFORE SHEARING OFF TO THE
NORTHEAST SUNDAY WITHIN A DEEP LAYERED TROUGH. MEANWHILE ACROSS
FLORIDA...ABOVE NORMAL TEMPERATURES WILL PREVAIL THROUGH THE PERIOD
WITH MOIST SPRING-LIKE DEW POINTS EXPECTED SUNDAY NIGHT THROUGH MUCH
OF MONDAY BEFORE THE FRONTAL PASSAGE. THE COLD FRONT ASSOCIATED
WITH THE AFOREMENTIONED TROUGH PUSH ACROSS THE FORECAST AREA AT A
FAIRLY PROGRESSIVE CLIP FROM NORTHWEST TO SOUTHEAST...STARTING EARLY
MONDAY ACROSS THE NATURE COAST AND OVER THE REMAINDER OF THE AREA
THROUGH MONDAY NIGHT. MUCH OF THE AREA WILL CLEAR OUT TUESDAY AND
CHRISTMAS DAY WEDNESDAY BEFORE A WEAK VORT MAX PASSES OVER THE
REGION WITHIN A SOUTHWEST MID-UPR LEVEL FLOW AND FORCES WEAK
ISENTROPIC UPGLIDE TO PRODUCE CLOUDINESS AND SOME LIGHT SHOWERS
LATER IN THE PERIOD.
&&
.AVIATION...
20/18Z-21/18Z...PREVAILING VFR FOR THE REST OF TODAY WITH SCT TO LCL
BKN CLOUDS AND POSSIBLY ISOLD SHRA BUT WITH LITTLE IMPACT ON THE
TERMINALS. SE WINDS WITH SOME GUSTS DURING THIS AFTERNOON.
INCREASING LOW-LEVEL MOISTURE WILL RESULT IN MVFR VSBY OR CIGS
TOWARD SUNRISE SAT THEN VFR AFTER 14-15Z. SE WINDS CONTINUE AND
BECOME GUSTY SAT.
&&
.MARINE...
HIGH PRESSURE SHIFTING EASTWARD INTO THE ATLANTIC HAS ALLOWED WINDS
OVER THE EASTERN GULF TO SHIFT FROM EASTERLY TO SOUTHEASTERLY. A
SLOW MOVING COLD FRONT WILL APPROACH THE EASTERN GULF WATERS DURING
THE SECOND HALF OF THE UPCOMING WEEKEND...BUT NOT PASS THROUGH THE
WATERS UNTIL THE EARLY PART OF NEXT WEEK. AHEAD OF THE APPROACHING
COLD FRONT THE PRESSURE GRADIENT WILL TIGHTEN WHICH WILL SUPPORT
WINDS AND SEAS APPROACHING CAUTIONARY LEVELS AT TIMES LATE TONIGHT
THROUGH SUNDAY...ESPECIALLY AWAY FROM SHORE.
&&
.FIRE WEATHER...
LOW LEVEL MOISTURE CONTINUES TO INCREASE ACROSS THE REGION AND WILL
PREVENT ANY CHANCE OF CRITICALLY LOW RELATIVE HUMIDITY LEVELS THE
NEXT SEVERAL DAYS. A FRONT WILL APPROACH LATE IN THE WEEKEND...BUT
WILL NOT CROSS THE FLORIDA PENINSULA UNTIL THE EARLY PORTION OF NEXT
WEEK. FIRE WEATHER CONCERNS THROUGH THE WEEKEND WILL INCLUDE
ELEVATED DISPERSION INDICES BOTH SATURDAY AND SUNDAY AFTERNOON AND
THE POTENTIAL FOR AREAS OF LATE NIGHT AND EARLY MORNING FOG BOTH
FRIDAY NIGHT AND SATURDAY NIGHT.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 68 84 68 82 / 10 10 10 10
FMY 67 86 67 84 / 10 10 10 10
GIF 62 84 65 85 / 10 10 10 10
SRQ 66 83 66 81 / 10 10 10 10
BKV 64 85 64 84 / 10 10 10 10
SPG 68 81 68 81 / 10 10 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...RUDE
LONG TERM...LAMARRE
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
935 AM EST FRI DEC 20 2013
.UPDATE (REST OF TODAY THROUGH SATURDAY)...
14Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFYING UPPER LEVEL
PATTERN OVER THE CONUS. LONGWAVE TROUGHING NOW COVERS THE NATION TO
THE WEST OF THE CONTINENTAL DIVIDE...AND IS HIGHLIGHTED BY A POTENT
SHORTWAVE/CLOSED LOW FEATURE EJECTING EASTWARD OVER THE SW STATES
AND NORTHERN MEXICO. THE ADVANCEMENT OF THIS WESTERN TROUGH AND
ASSOCIATED HEIGHT FALLS HAVE HELPED TO "RIDGE UP" THE DOWNSTREAM
FLOW FROM THE EASTERN GULF OF MEXICO TO THE MID-ATLANTIC STATES.
THIS RIDGE OVER OUR HEADS WILL BE OUR PROTECTOR THROUGH THE UPCOMING
WEEKEND AND PROVIDE A GENERALLY FAIR AND UNSEASONABLY WARM FORECAST.
WV IMAGERY SHOWS SOUTHERN STREAM MOISTURE RAPIDLY ADVECTING
NORTHWARD ACROSS THE SOUTHERN PLAINS AHEAD OF THE STRONG SOUTHWEST
SHORTWAVE. THIS MOISTURE RETURN IS THE FIRST STAGE IN THE PRIMING OF
THE ATMOSPHERE FOR A POTENTIALLY SIGNIFICANT SEVERE WEATHER OUTBREAK
ACROSS THE LOWER MS VALLEY DURING SATURDAY. HOWEVER...AS MENTIONED
ABOVE THIS INCLEMENT WEATHER IS NOT IN OUR FORECAST WITH THE UPPER
RIDGE IN PLACE. 20/12Z KTBW SOUNDING...ALTHOUGH STILL ON THE DRY
SIDE...SHOWS THAT WE HAVE SEEN SOME MOISTURE RETURN THROUGH THE
COLUMN DURING THE PAST 24 HOURS...WITH THE PW VALUE JUMPING FROM
0.27" ON THURSDAY MORNING TO AROUND AN INCH THIS MORNING. MUCH OF
THIS MOISTURE RETURN HAS BEEN IN THE LOWER LEVELS BELOW A WELL
DEFINED SUBSIDENCE INVERSION (ASSOCIATED WITH THE UPPER RIDGING)
JUST ABOVE 700MB.
AT THE SURFACE...HIGH PRESSURE RIDGES BACK FROM THE WESTERN ATLANTIC
TO THE GA/CAROLINA COAST...PLACING OUR REGION WITHIN A LIGHT
SOUTHEAST FLOW REGIME. THIS FLOW HAS BEEN ADVECTING INCREASING
LEVELS OF BOUNDARY LAYER MOISTURE ACROSS THE PENINSULA AND THESE
MOISTURE LEVELS WILL ONLY CONTINUE TO INCREASE THROUGH THE NEXT 24
HOURS. TEMPERATURES ARE ALREADY RISING QUICKLY THROUGH THE 60S
TOWARD ABOVE NORMAL AFTERNOON TEMPERATURES.
REST OF TODAY...
SUNNY/MOSTLY SUNNY SKIES THIS MORNING WILL GIVE WAY TO A MIX OF SUN
AND CLOUDS UNDER A DEVELOPING SCT-BKN CUMULUS FIELD FOR THE
AFTERNOON. EFFICIENT DIURNAL MIXING AND A WARM POTENTIAL WITH 850MB
TEMPS OF 13-15C WILL ALLOW HIGH TEMPS TO REACH THE MID/UPPER 70S
ACROSS THE NORTHERN NATURE COAST...TO THE LOWER 80S AROUND THE I-4
CORRIDOR...AND LOWER TO MIDDLE 80S DOWN TOWARD FORT MYERS. THE
ENHANCED TERRESTRIAL HEATING AND A GENERALLY WEAK GRADIENT SHOULD
ALLOW FOR A FEEBLE SEA-BREEZE CIRCULATION TO TURN WINDS ONSHORE AT
THE BEACHES DURING THE AFTERNOON. WHILE NOT ANTICIPATING MUCH
ACTIVITY...THE WARM TEMPS AND MOISTURE RETURN ARE SHOWN TO RESULT IN
SEVERAL HUNDRED J/KG OF CAPE THIS AFTERNOON FROM THE TAMPA BAY AREA
SOUTHWARD. THIS INSTABILITY COMBINED WITH SOME ENHANCED FOCUS ALONG
ANY SEA-BREEZE MAY BE JUST ENOUGH TO FORCE A FEW ISOLATED SHOWERS.
ANY SHOWERS WILL BE BRIEF AND HAVE VERY LIMITED IMPACTS TO
OUTDOOR ACTIVITIES...BUT HAVE KEPT THE 20% POP FOR THIS
POSSIBILITY. LOOKING AT THE KTBW SOUNDING PROFILE...ANY SHOWERS WILL
ALSO BE SHALLOW IN NATURE...HELD IN CHECK BY THE STRONG SUBSIDENCE
INVERSION ABOVE 12-15KFT.
TONIGHT...A WARM AND FAIR OVERNIGHT PERIOD. THE CONTINUED MOISTURE
ADVECTION WITHIN THE LIGHT SE FLOW REGIME WILL PREVENT LOW TEMPS
FROM DROPPING OUT OF THE 60S FOR JUST ABOUT ALL AREAS. BOUNDARY
LAYER MOISTURE UNDERNEATH THE SUPPRESSION ALOFT DOES SET UP A
FAVORABLE SCENARIO FOR PATCHY/AREAS OF FOG DURING THE LATE NIGHT
HOURS. A WIDESPREAD DENSE FOG EVENT IS UNLIKELY...BUT LOCALIZED
AREAS OF REDUCED VISIBILITY ARE A GOOD BET FOR ANYONE DOING EARLY
TRAVELING SATURDAY MORNING. BOTH STATISTICAL MOS AND ENSEMBLE SREF
PROBS SUGGEST THIS FOG POTENTIAL.
SATURDAY...UNSEASONABLY WARM TEMPERATURES TO START OUT THE WEEKEND
UNDER AN UPPER RIDGE CHARACTERIZED BY H5 HEIGHTS OF 1.5-2 STANDARD
DEVIATIONS ABOVE CLIMO. GRADIENT WILL INCREASE SOMEWHAT AND SHOULD
HELP PREVENT MUCH IF ANY SEABREEZE DEVELOPMENT...OR AT LEAST INLAND
PENETRATION DESPITE THE STRONG TERRESTRIAL HEATING. THEREFORE...HAVE
A RAIN FREE DAY IN THE FORECAST. THE STRONGER GRADIENT WILL RESULT
IN EVEN MORE EFFICIENT DIURNAL MIXING WITHIN A VERY WARM POTENTIAL
COLUMN WITH 850MB TEMPS AROUND 16C. THESE 850MB TEMPS ARE ALSO 1.5-2
STANDARD DEVIATIONS ABOVE CLIMO. COMBINE ALL THIS AND WE ARE LOOKING
AT NEAR RECORD TEMPERATURES FOR THE WINTER SOLSTICE...WITH LOWER 80S
FAR NORTH AND WIDESPREAD MIDDLE 80S ELSEWHERE. BELOW IS A SELECT
LISTING OF SOME OF THE RECORD TEMPERATURES FOR DEC 21ST ACROSS THE
AREA:
BROOKSVILLE...86
FORT MYERS....87
LAKELAND......82
SARASOTA......86
PUNTA GORDA...84
ST PETERSBURG.82
TAMPA INTL....85
WINTER HAVEN..85
HAVE A GREAT FRIDAY AND BEGINNING TO THE WEEKEND! STAY COOL!
&&
.AVIATION...
20/12Z-21/12Z...PREVAILING VFR TODAY WITH FEW-SCT LOW AND MID
CLOUDS.ISOLD SHRA THIS AFTERNOON BUT WITH LOW ODDS OF IMPACTING THE
TERMINALS. LIGHT EAST WINDS BECOME SE AND INCREASE IN THE AFTERNOON.
A DEVELOPING WEATHER SYSTEM OVER THE SW U.S. WILL INCREASE LOW-LEVEL
MOISTURE THROUGH THE PERIOD WITH MVFR CONDITIONS TOWARD SUNRISE SAT.
&&
.MARINE...
WINDS WILL REMAIN OUT OF THE SOUTHEAST THROUGH THE WEEKEND WITH
SPEEDS REACHING EXERCISE CAUTION LEVELS STARTING LATER TONIGHT. A
COLD FRONT WILL APPROACH THE WATERS LATE IN THE WEEKEND INTO EARLY
NEXT WEEK WITH WINDS TURNING TO THE NORTHWEST AND SPEEDS INCREASING
AGAIN EARLY TO MID WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 81 68 84 68 / 20 10 10 10
FMY 84 66 86 68 / 20 10 10 10
GIF 82 64 84 65 / 10 10 10 10
SRQ 82 67 84 67 / 20 10 10 10
BKV 82 61 85 62 / 20 10 10 10
SPG 79 67 81 68 / 20 10 10 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE...MROCZKA
AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
608 AM EST FRI DEC 20 2013
.SYNOPSIS...
HIGH PRESSURE CENTERED OFF THE COAST WILL RIDGE INTO THE
SOUTHEASTERN STATES THROUGH SATURDAY. SOUTHERLY FLOW ON THE
BACKSIDE OF THE HIGH WILL BRING WARM TEMPERATURES TO THE FORECAST
AREA. A COLD FRONT WILL SLOWLY MOVE THROUGH OUR REGION SUNDAY
NIGHT INTO MONDAY. COOL AND DRY HIGH PRESSURE WILL RETURN TUESDAY
AND WEDNESDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MOISTURE HAS INCREASED IN THE SOUTHERLY FLOW ON THE BACKSIDE OF
THE OFFSHORE HIGH. THIS SHALLOW MOISTURE PLUS NOCTURNAL COOLING
HAS RESULTED IN STRATUS AND FOG MAINLY IN SOUTHERN AND EASTERN
SECTIONS. STRATUS HAS BEEN MORE DOMINATE BECAUSE OF SIGNIFICANT
BOUNDARY-LAYER WIND. HEATING AND MIXING SHOULD HELP DIMINISH THE
LOWER CLOUDINESS LATER THIS MORNING. THE HRRR INDICATES THIS WILL
HAPPEN BETWEEN 1000 AM AND 1100 AM. SATELLITE TRENDS INDICATE
UPPER-LEVEL CLOUDINESS WILL CONTINUE TO STREAM INTO THE AREA...BUT
THIS CLOUDINESS SHOULD GENERALLY BE THIN ENOUGH FOR PARTLY SUNNY
SKIES. WE USED THE GUIDANCE CONSENSUS FOR THE HIGH TEMPERATURE
FORECAST.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
HIGH PRESSURE OFF THE COAST WILL CONTINUE TO CIRCULATE A SOUTHERLY
FLOW INTO THE FORECAST AREA AHEAD OF A SLOW MOVING COLD FRONT.
EXPECT WIDESPREAD STRATUS WILL DEVELOP TONIGHT BECAUSE OF HIGH LOW-
LEVEL MOISTURE AND NOCTURNAL COOLING. THIS CLOUDINESS SHOULD
CONTINUE THROUGH MUCH OF SATURDAY MORNING...BUT HEATING AND MIXING
SHOULD DIMINISH THE CLOUDINESS LATE IN THE MORNING OR EARLY IN
THE AFTERNOON. MUCH OF THE FORCING ASSOCIATED WITH THE
APPROACHING COLD FRONT WILL REMAIN WEST OF THE FORECAST AREA
THROUGH SATURDAY NIGHT BUT THE MOISTURE MAY BECOME DEEP ENOUGH FOR
SHOWERS BY SATURDAY NIGHT. WE FORECASTED JUST CHANCE POPS. ABOVE
NORMAL TEMPERATURES WILL OCCUR IN THE WARM SECTOR AHEAD OF THE
FRONT. WE USED THE GUIDANCE CONSENSUS FOR THE HIGH TEMPERATURE
FORECAST. THE TIMING OF DIMINISHING STRATUS SATURDAY ADDS UNCERTAINTY
TO THE TEMPERATURE FORECAST.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
THE WARM PATTERN AHEAD OF THE COLD FRONT WILL CONTINUE SUNDAY.
HIGH PRESSURE WELL OFF THE EAST COAST WILL CIRCULATE INCREASING
MOISTURE INTO THE FORECAST AREA FROM THE ATLANTIC AND GULF OF
MEXICO. MUCH OF THE FORCING ASSOCIATED WITH THE APPROACHING COLD
FRONT WILL STILL BE WEST OF THE AREA SO WE FORECASTED JUST CHANCE
POPS SUNDAY. THE GREATER SHOWER CHANCE SHOULD BE SUNDAY NIGHT AND
MONDAY MAINLY BECAUSE OF CONVERGENCE ALONG THE FRONT PLUS LIFT
ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF THE H25 JET. THERE
MAY BE ENOUGH INSTABILITY FOR A FEW THUNDERSTORMS LATE SUNDAY AND
SUNDAY NIGHT. SHEAR WILL BE HIGH BUT INSTABILITY WEAK LIMITING THE
SEVERE THUNDERSTORM THREAT. THE GFS AND ECMWF SHOW DRY RIDGING
BEHIND THE FRONT DOMINATING TUESDAY AND WEDNESDAY. THE MODELS SHOW
A TROUGH OFF THE COAST THURSDAY SUPPORTING A SMALL RAIN CHANCE.
VERY WARM TEMPERATURES WILL OCCUR AHEAD OF THE FRONT SUNDAY WITH
MORE SEASONABLE TEMPERATURES DURING THE REST OF THE MEDIUM-RANGE
PERIOD. THE GFS...ECWMF...AND EKD MOS SUPPORT HIGHS NEAR 80 AHEAD
OF THE FRONT SUNDAY. THE GFS ENSEMBLES HAD A HIGH SPREAD WITH THE
MEAN MAINLY IN THE LOWER 70S. WE LEANED TOWARD THE WARMER
GUIDANCE...BUT THE EXTENT OF STRATUS ADDS UNCERTAINTY TO THE
TEMPERATURE FORECAST.
&&
.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
MOISTURE HAS INCREASED IN THE SOUTHERLY FLOW ON THE BACKSIDE OF
THE OFFSHORE HIGH. THIS SHALLOW MOISTURE PLUS NOCTURNAL COOLING
HAS RESULTED IN MVFR STRATUS AND FOG MAINLY IN SOUTHERN AND
EASTERN SECTIONS. STRATUS HAS BEEN MORE DOMINATE BECAUSE OF
SIGNIFICANT BOUNDARY-LAYER WIND. HEATING AND MIXING SHOULD HELP
DIMINISH THE LOWER CLOUDINESS LATER THIS MORNING. THE HRRR
INDICATES THIS WILL HAPPEN BETWEEN 1000 AM AND 1100 AM AND VFR
CONDITIONS SHOULD OCCUR DURING THE AFTERNOON INTO THE EVENING.
HOWEVER...HIGH LOW-LEVEL MOISTURE IN THE SOUTHERLY FLOW AND
NOCTURNAL COOLING WILL BRING MVFR OR IFR STRATUS OR FOG LATE
TONIGHT.
EXTENDED AVIATION OUTLOOK...HIGH CONFIDENCE FOR CEILING AND VISIBILITY
RESTRICTIONS THROUGH MONDAY ASSOCIATED WITH THE SLOW MOVING COLD
FRONT.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
416 PM CST FRI DEC 20 2013
.DISCUSSION...
337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW...
TONIGHT THROUGH SATURDAY MORNING...
325 PM CST...
TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR
FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE
CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER
VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID-
LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN
THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS.
THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR
MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH
THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY
TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE
ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW
FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY
TO EXPERIENCE SOME GLAZING TOO.
THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7
PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW
POINTS SEEP IN.
FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE
TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE
THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY
AT BEST AND LIGHT AFTER 7-8 PM.
SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON
MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED
BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND
INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO
THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE
AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN
AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY
HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION
OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF
I-80.
MTF
DISCUSSION ON WINTER STORM.
WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND
CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES.
THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR
THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A
NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND
MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY
NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS
NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER
AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS.
THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH
TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY
NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS
FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY
SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION
ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL
LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH
SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT
TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR
ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL
LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING
AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE
COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS
OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET
IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER
NORTHWEST TRACK...I CHOOSE TO HOLD OFF.
THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET
ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING
AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN
RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS
MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING
SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF
SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF
I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE
CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY
RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING
THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE
EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE
AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN
AN SPS.
IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY
SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH.
STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY
PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND
WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE
EXPECTED.
THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR
TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW
ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS
THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY
LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS.
TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET
CLOSE TO CHICAGO AND INTERSTATE 80.
MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT
PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL
DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS
IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER
REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA.
KJB
EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING
THE CHRISTMAS HOLIDAY...
300 PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 22Z...
* NNE WINDS BECOMING NNW 02Z/8 PM CST-ISH THIS EVENING.
* CONTINUED IFR CIGS/MVFR VSBY WITH SOME LGT DZ/BR.
* NE WINDS AGAIN BY MID-MORNING SATURDAY.
* MIXED PCPN...IP/RA/FZRA POTENTIAL SAT AFTN/EVE.
RATZER
//DISCUSSION...UPDATED 18Z...
SO FAR AT MDW/ORD/GYY THE TEMPERATURES HAVE REMAINED ENOUGH ABOVE
FREEZING THAT ICE AT THE SFC HAS NOT BEEN A PROBLEM. DPA HAS BEEN
RIGHT ON THE LINE BUT STILL ABOVE FREEZING...WHILE RFD HAS BEEN
HAVING CONSIDERABLE ICE PROBLEMS. RADAR TRENDS SUGGEST ORD/MDW
PRECIP MAY END A BIT SOONER THAN PREVIOUSLY EXPECTED THIS
AFTERNOON...AND FCST SOUNDINGS SUGGEST INCOMING COLD AIR WOULD
PRODUCE ONLY A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE AT WORST.
AFTER A BREAK IN PRECIP OVERNIGHT INTO TOMORROW MORNING...THE
NEXT LOW PRESSURE SYSTEM BEGINS AFFECTING THE AREA. AS PRECIP
DEVELOPS TOWARD MIDDAY TOMORROW...AGAIN THE FREEZING LINE WILL LIE
VERY CLOSE TO THE TERMINALS. TAFS REFLECT THE MORE OPTIMISTIC VIEW
THAT ORD/MDW REMAIN ON THE LIQUID SIDE AT LEAST THROUGH THE
AFTERNOON.
IF PRECIP REMAINS MOSTLY LIQUID THEN CIG/VSBY AND WIND TRENDS WILL
BE THE BIGGER ISSUES. AM NOT SEEING MUCH EITHER IN THE
OBSERVATIONS OR IN FCST GUIDANCE TO SUGGEST CIGS WILL IMPROVE
ABOVE IFR THROUGH THE AFTERNOON...AND SOME POSSIBILITY EXISTS FOR
LIFR. VSBYS ARE IN SLIGHTLY BETTER SHAPE.
STILL THINK WINDS WILL BACK TO NORTHWEST BY THIS EVENING THEN
FLUCTUATE BETWEEN NNW AND NNW TONIGHT AND TOMORROW AS THE LOW
PRESSURE SYSTEMS TO OUR SOUTH MIGRATE THROUGH THE AREA.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 22Z...
* MEDIUM CONFIDENCE IN TIMING OF WIND SHIFT FROM NE TO NNW BY MID-
EVENING.
* HIGH CONFIDENCE IN IFR CIGS REMAINING OVC006-008 AND VSBYS
GENERALLY 3-6SM IN BR/PATCHY -DZ NEXT SEVERAL HOURS.
* LOW CONFIDENCE ON CIG TRENDS OVERNIGHT.
* MEDIUM CONFIDENCE ON TIMING OF PRECIP TOMORROW BUT LOW
CONFIDENCE IN PRECIP TYPE TOMORROW AFTERNOON.
RATZER/LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 7 PM FRIDAY.
WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011...6 PM SATURDAY TO 6 PM SUNDAY.
WINTER STORM WATCH...ILZ006-ILZ012...6 PM SATURDAY TO 6 PM
SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 7 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 PM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
337 PM CST FRI DEC 20 2013
.DISCUSSION...
337 PM CST...INCLUDING UPDATED WINTER STORM DISCUSSION BELOW...
TONIGHT THROUGH SATURDAY MORNING...
325 PM CST...
TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR
FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE
CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER
VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID-
LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN
THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS.
THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR
MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH
THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY
TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE
ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW
FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY
TO EXPERIENCE SOME GLAZING TOO.
THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7
PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW
POINTS SEEP IN.
FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE
TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE
THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY
AT BEST AND LIGHT AFTER 7-8 PM.
SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON
MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED
BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND
INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO
THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE
AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN
AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY
HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION
OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF
I-80.
MTF
DISCUSSION ON WINTER STORM.
WE HAVE UPGRADED PORTIONS OF THE WINTER STORM WATCH TO WARNING AND
CONTINUED THE WATCH FOR LAKE AND KANE COUNTIES.
THE VIGOROUS MID LEVEL FEATURE...CURRENTLY NOTED IN WATER VAPOR NEAR
THE BAJA OF CALIFORNIA EARLY THIS AFTERNOON IS FORECAST TO TAKE ON A
NEGATIVE TILT AS IT MOVES OUT ACROSS THE TEXAS PANHANDLE AROUND
MIDDAY ON SATURDAY. THIS FEATURE WILL LIFT QUICKLY
NORTH-NORTHEASTWARD ACROSS THE MID MISSISSIPPI VALLEY AND ACROSS
NORTHERN ILLINOIS SATURDAY NIGHT. MODEL GUIDANCE CONTINUES TO WAVER
AROUND A BIT ON THE ACTUAL TRACK OF THE 850 AND SURFACE LOWS.
THEREFORE...I HAVE TRENDED CLOSER TO THE ENSEMBLE MEANS...WHICH
TRACK THE 850 LOW RIGHT ACROSS NORTHEASTERN ILLINOIS LATE SATURDAY
NIGHT. THIS TRACK FAVORS NORTH CENTRAL AND FAR NORTHEASTERN ILLINOIS
FOR THE HEAVIEST SNOWFALL...ESPECIALLY SATURDAY NIGHT INTO EARLY
SUNDAY AS STRONG FRONTOGENESIS SETS UP WITHIN THE DEFORMATION
ZONE...JUST TO THE NORTH AND WEST OF THE 850 LOW TRACK. THIS WILL
LIKELY SUPPORT AN AREA OF HEAVY SNOWFALL ACROSS THESE AREAS...WITH
SNOW RATES LIKELY TO REACH OR EVEN EXCEED AN 1 INCH PER HOUR AT
TIMES...GIVEN THE GOOD COUPLING OF THE LARGE SCALE FORCING FOR
ASCENT FROM THE MID LEVEL WAVE AND THE GOOD FRONTOGENESIS. MID LEVEL
LAPSE RATES WILL ALSO SUPPORT GOOD SNOWFALL ACROSS THE WARNING
AREAS. I CHOSE TO LEAVE THE WATCH IN PLACE FOR LAKE AND KANE
COUNTIES. THESE AREAS MAY ALSO SEE 6+ INCHES OF SNOW...IN PORTIONS
OF THE COUNTIES...BUT DUE TO THE POTENTLY FOR SOME SLIGHT SHIFTS YET
IN THE TRACK OF THE SYSTEM...WITH A POTENTIAL FOR A FARTHER
NORTHWEST TRACK...I CHOOSE TO HOLD OFF.
THE OTHER CONCERN IS THE THREAT FOR FREEZING RAIN AND SLEET
ACCUMULATIONS...ESPECIALLY ACROSS SOUTHERN SECTIONS OF THE WARNING
AREA...AND PLACES TO THE SOUTH. TEMPERATURES ARE EXPECTED TO REMAIN
RIGHT AROUND THE FREEZING POINT...SO IT APPEARS THAT ICING AMOUNTS
MAY BE LIMITED SOME...ESPECIALLY NEAR CHICAGO. WITH THAT BEING
SAID...I STILL THINK THERE IS A DECENT POTENTIAL TO HAVE AN AREA OF
SOME ICE ACCUMULATIONS...OF 0.1 TO 0.2 INCHES...PRIMARILY NORTH OF
I-80 UP TO AROUND THE I-88 CORRIDOR. CLOSER TO THE LAKE AND THE
CITY ICE AMOUNTS MAY BE LESS DUE TO THE FLOW OFF THE LAKE POSSIBLY
RESULTING IN TEMPS JUST ABOVE FREEZING. IT APPEARS THE MAIN ICING
THREAT WILL NOT OCCUR UNTIL TOMORROW AFTERNOON AND INTO THE
EVENING. THEREFORE...WE HAVE SOME TIME TO BETTER IRON OUT THE
AREAS MOST SUSCEPTIBLE TO ICING. WE WILL HIGHLIGHT THIS THREAT IN
AN SPS.
IT ALSO APPEARS THE HEAVY RAIN THREAT WILL MAINLY BE ACROSS MY
SOUTHEASTERN COUNTIES...SO NO CHANGES TO THE GOING FLOOD WATCH.
STRONG MOISTURE CONVERGENCE AND ANOMALOUSLY HIGH PWATS WILL LIKELY
PRODUCE AMOUNTS IN EXCESS OF AN INCH OR SO ACROSS THESE AREAS...AND
WITH ALL OF THIS BECOMING RUNOFF...RAPID RISES ON AREA STREAMS ARE
EXPECTED.
THE SNOW THREAT FOR AREAS SOUTH OF THE CURRENT WARNING AREA APPEAR
TO SOMEWHAT LIMITED...WITH A SHARP GRADIENT IN THE SNOW
ACCUMULATIONS EXPECTED. AN IMPRESSIVE DRY SLOT WILL PUNCH IN ACROSS
THE AREA LATE SATURDAY NIGHT INTO SUNDAY...LIKELY RESULT IN ONLY
LIGHT SNOW OR EVEN FZ DRIZZLE GIVEN THE LOSE OF ICE IN THE CLOUDS.
TOTAL SNOW AMOUNTS LOOK TO DROP TO UNDER AN INCH BY THE TIME YOU GET
CLOSE TO CHICAGO AND INTERSTATE 80.
MUCH COLDER AIR SPILLS IN ACROSS THE AREA SUNDAY NIGHT...WITH LIGHT
PRECIP CONTINUING IN ASSOCIATION WILL ANOTHER UPPER LEVEL
DISTURBANCE. TEMPERATURES WILL LIKELY DROP INTO THE SINGLE DIGITS
IN MOST AREAS SUNDAY NIGHT. THUS...ANY STANDING WATER
REMAINING...WITH LIKELY QUICKLY FREEZE IN PLACE ACROSS THE AREA.
KJB
EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING
THE CHRISTMAS HOLIDAY...
300 PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING IFR CIG/VSBY TRENDS.
* PRECIPITATION ENDING TIME AND POSSIBLE LIGHT FREEZING RAIN TODAY.
* WINDS BACKING NORTH THEN NORTHWEST.
LENNING
//DISCUSSION...UPDATED 18Z...
SO FAR AT MDW/ORD/GYY THE TEMPERATURES HAVE REMAINED ENOUGH ABOVE
FREEZING THAT ICE AT THE SFC HAS NOT BEEN A PROBLEM. DPA HAS BEEN
RIGHT ON THE LINE BUT STILL ABOVE FREEZING...WHILE RFD HAS BEEN
HAVING CONSIDERABLE ICE PROBLEMS. RADAR TRENDS SUGGEST ORD/MDW
PRECIP MAY END A BIT SOONER THAN PREVIOUSLY EXPECTED THIS
AFTERNOON...AND FCST SOUNDINGS SUGGEST INCOMING COLD AIR WOULD
PRODUCE ONLY A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE AT WORST.
AFTER A BREAK IN PRECIP OVERNIGHT INTO TOMORROW MORNING...THE
NEXT LOW PRESSURE SYSTEM BEGINS AFFECTING THE AREA. AS PRECIP
DEVELOPS TOWARD MIDDAY TOMORROW...AGAIN THE FREEZING LINE WILL LIE
VERY CLOSE TO THE TERMINALS. TAFS REFLECT THE MORE OPTIMISTIC VIEW
THAT ORD/MDW REMAIN ON THE LIQUID SIDE AT LEAST THROUGH THE
AFTERNOON.
IF PRECIP REMAINS MOSTLY LIQUID THEN CIG/VSBY AND WIND TRENDS WILL
BE THE BIGGER ISSUES. AM NOT SEEING MUCH EITHER IN THE
OBSERVATIONS OR IN FCST GUIDANCE TO SUGGEST CIGS WILL IMPROVE
ABOVE IFR THROUGH THE AFTERNOON...AND SOME POSSIBILITY EXISTS FOR
LIFR. VSBYS ARE IN SLIGHTLY BETTER SHAPE.
STILL THINK WINDS WILL BACK TO NORTHWEST BY THIS EVENING THEN
FLUCTUATE BETWEEN NNW AND NNW TONIGHT AND TOMORROW AS THE LOW
PRESSURE SYSTEMS TO OUR SOUTH MIGRATE THROUGH THE AREA.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW CONFIDENCE ABOUT EXACT CIG/VSBY TRENDS THIS AFTERNOON BUT
FAVOR MOSTLY IFR WITH OCCASIONAL LIFR CIGS AND VFR VSBYS.
* WINDS HAVE BEEN STEADY NNE BUT STILL MEDIUM TO HIGH CONFIDENCE
THAT TREND WILL VERY SOON BE MORE NORTHERLY THIS AFTERNOON.
* LOW CONFIDENCE ON HOW LOW CIGS GO OVERNIGHT.
* MEDIUM CONFIDENCE ON TIMING OF PRECIP TOMORROW BUT LOW
CONFIDENCE IN PRECIP TYPE TOMORROW AFTERNOON.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 7 PM FRIDAY.
WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011...6 PM SATURDAY TO 6 PM SUNDAY.
WINTER STORM WATCH...ILZ006-ILZ012...6 PM SATURDAY TO 6 PM
SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 7 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 PM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
330 PM CST FRI DEC 20 2013
.DISCUSSION...
303 PM CST...
DISCUSSION ON WINTER STORM WILL BE ISSUED SHORTLY.
HEADLINE NOTES FOR STORM...
A WINTER STORM WARNING WILL BE ISSUED FOR:
WINNEBAGO...LEE...OGLE...BOONE...MCHENRY AND DEKALB COUNTIES.
THE WINTER STORM WATCH WILL REMAIN IN EFFECT FOR KANE AND LAKE
COUNTIES IN ILLINOIS.
A FLOOD WATCH REMAINS IN EFFECT FOR:
FORD...IROQUOIS...NEWTON...JASPER AND BENTON COUNTIES.
RC
TONIGHT THROUGH SATURDAY MORNING...
325 PM CST...
TONIGHT...THE FREEZING RAIN ADVISORY CONTINUES THROUGH 7 PM FOR
FAR NORTHERN IL AS LIGHT SHOWER ACTIVITY AND PATCHY DRIZZLE
CONTINUE TO OVERRIDE A SUBFREEZING BOUNDARY LAYER. THE GOES WATER
VAPOR LOOP SHOWS MODEST DRYING OVER THE AREA IN THE MID-
LEVELS...BUT JUST ENOUGH WEAK ASCENT APPEARS TO BE PRESENT WITHIN
THE LOW-LEVEL SATURATION TO KEEP TRIGGERING THESE LIGHT SHOWERS.
THE FREEZING DEMARCATION HELD STEADY MUCH OF TODAY FROM NEAR
MENDOTA NORTHEAST TO LAKE COUNTY IL. DO NOT SEE MUCH SHIFT WITH
THAT THROUGH EARLY THIS EVE. SO WITH IT BEING A BUSY HOLIDAY
TRAVEL TIME ADDED TO THE NORMAL FRIDAY COMMUTE...CERTAINLY LET THE
ADVISORY CONTINUE TO 7 PM. AS TEMPERATURES SLOWLY FALL BELOW
FREEZING SOUTH OF THE ADVISORY...UNTREATED WET ROADWAYS ARE LIKELY
TO EXPERIENCE SOME GLAZING TOO.
THE DENSE FOG ADVISORY FOR SOUTHERN AREAS SHOULD BE FINE ENDING AT 7
PM AS WINDS BEGIN TO INCREASE BEHIND THE BOUNDARY AND LOWER DEW
POINTS SEEP IN.
FORCING REMAINS WEAK THROUGH MUCH OF TONIGHT WITH LIMITED MOISTURE
TRANSPORT AND REALLY ANY TYPE OF MID-LEVEL WAVE/TRIGGER. SO WHILE
THERE IS A CHANCE FOR FREEZING DRIZZLE...ANY PRECIP SHOULD BE PATCHY
AT BEST AND LIGHT AFTER 7-8 PM.
SATURDAY MORNING...THE RAP AND OTHER HIGH RES GUIDANCE KEY IN ON
MOISTURE TRANSPORT AHEAD OF THE MAIN DEVELOPING SYSTEM /DESCRIBED
BELOW/ ADVANCING INTO THE SOUTHERN CWA IN THE PRE-DAWN HOURS AND
INTO SAT MORNING. THE CONVERGENCE AT THE NOSE OF THIS CREEPS INTO
THE SOUTHERN FORECAST AREA IN THE MORNING...WHERE FREEZING DRIZZLE
AND RAIN LOOK POSSIBLE...THOUGH THERE COULD BE QUITE A BIT OF RAIN
AND CONVECTIVE ACTIVITY ACROSS THE MID-MISSISSIPPI VALLEY THAT MAY
HALT THE FRONT EDGE ADVANCE OF THE PRECIP. HAVE CONTINUED MENTION
OF LIGHT FREEZING PRECIP SAT MORNING ACROSS AREAS MAINLY SOUTH OF
I-80.
MTF
EXTENDED FORECAST PERIOD /MONDAY MORNING THROUGH FRIDAY INCLUDING
THE CHRISTMAS HOLIDAY...
300 PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING IFR CIG/VSBY TRENDS.
* PRECIPITATION ENDING TIME AND POSSIBLE LIGHT FREEZING RAIN TODAY.
* WINDS BACKING NORTH THEN NORTHWEST.
LENNING
//DISCUSSION...UPDATED 18Z...
SO FAR AT MDW/ORD/GYY THE TEMPERATURES HAVE REMAINED ENOUGH ABOVE
FREEZING THAT ICE AT THE SFC HAS NOT BEEN A PROBLEM. DPA HAS BEEN
RIGHT ON THE LINE BUT STILL ABOVE FREEZING...WHILE RFD HAS BEEN
HAVING CONSIDERABLE ICE PROBLEMS. RADAR TRENDS SUGGEST ORD/MDW
PRECIP MAY END A BIT SOONER THAN PREVIOUSLY EXPECTED THIS
AFTERNOON...AND FCST SOUNDINGS SUGGEST INCOMING COLD AIR WOULD
PRODUCE ONLY A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE AT WORST.
AFTER A BREAK IN PRECIP OVERNIGHT INTO TOMORROW MORNING...THE
NEXT LOW PRESSURE SYSTEM BEGINS AFFECTING THE AREA. AS PRECIP
DEVELOPS TOWARD MIDDAY TOMORROW...AGAIN THE FREEZING LINE WILL LIE
VERY CLOSE TO THE TERMINALS. TAFS REFLECT THE MORE OPTIMISTIC VIEW
THAT ORD/MDW REMAIN ON THE LIQUID SIDE AT LEAST THROUGH THE
AFTERNOON.
IF PRECIP REMAINS MOSTLY LIQUID THEN CIG/VSBY AND WIND TRENDS WILL
BE THE BIGGER ISSUES. AM NOT SEEING MUCH EITHER IN THE
OBSERVATIONS OR IN FCST GUIDANCE TO SUGGEST CIGS WILL IMPROVE
ABOVE IFR THROUGH THE AFTERNOON...AND SOME POSSIBILITY EXISTS FOR
LIFR. VSBYS ARE IN SLIGHTLY BETTER SHAPE.
STILL THINK WINDS WILL BACK TO NORTHWEST BY THIS EVENING THEN
FLUCTUATE BETWEEN NNW AND NNW TONIGHT AND TOMORROW AS THE LOW
PRESSURE SYSTEMS TO OUR SOUTH MIGRATE THROUGH THE AREA.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW CONFIDENCE ABOUT EXACT CIG/VSBY TRENDS THIS AFTERNOON BUT
FAVOR MOSTLY IFR WITH OCCASIONAL LIFR CIGS AND VFR VSBYS.
* WINDS HAVE BEEN STEADY NNE BUT STILL MEDIUM TO HIGH CONFIDENCE
THAT TREND WILL VERY SOON BE MORE NORTHERLY THIS AFTERNOON.
* LOW CONFIDENCE ON HOW LOW CIGS GO OVERNIGHT.
* MEDIUM CONFIDENCE ON TIMING OF PRECIP TOMORROW BUT LOW
CONFIDENCE IN PRECIP TYPE TOMORROW AFTERNOON.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 7 PM FRIDAY.
WINTER STORM WARNING...ILZ003-ILZ004-ILZ005-ILZ008-ILZ010-
ILZ011...6 PM SATURDAY TO 6 PM SUNDAY.
WINTER STORM WATCH...ILZ006-ILZ012...6 PM SATURDAY TO 6 PM
SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 7 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 PM FRIDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
304 PM CST FRI DEC 20 2013
.DISCUSSION...
303 PM CST...
DISCUSSION ON WINTER STORM WILL BE ISSUED SHORTLY.
HEADLINE NOTES FOR STORM...
A WINTER STORM WARNING WILL BE ISSUED FOR:
WINNEBAGO...LEE...OGLE...BOONE...MCHENRY AND DEKALB COUNTIES.
THE WINTER STORM WATCH WILL REMAIN IN EFFECT FOR KANE AND LAKE
COUNTIES IN ILLINOIS.
A FLOOD WATCH REMAINS IN EFFECT FOR:
FORD...IROQUOIS...NEWTON...JASPER AND BENTON COUNTIES.
RC
PREVIOUS DISCUSSIONS...1155 AM CST
WATER VAPOR SHOWS SOME RELATIVE DRYING MOVING OVER THE AREA IN
THIS DEEP SOUTHWEST MOIST PLUME AND THAT ALONG WITH JUST LESS
ASCENT IS LIKELY RESPONSIBLE FOR THE DIMINISHING SHOWER COVERAGE.
THIS TREND SHOULD SLOWLY CONTINUE ALTHOUGH PROFILES REMAIN AT
LEAST SUPPORTIVE OF DRIZZLE THROUGH THE AFTERNOON. THE FREEZING
LINE HAS MAINTAINED ITS GROUND THROUGH THE PAST SEVERAL HOURS AND
EXPECT VERY LITTLE CHANGE WITH THAT THROUGH MID AFTERNOON...HENCE
THE PRESERVING OF THE FREEZING RAIN ADVISORY.
WHILE VISIBILITY OBSERVATIONS OF DENSE FOG ARE FAR MORE SPOTTY IN
THE SOUTHERN CWA THAN THEY WERE THIS MORNING...THE SHOWERS HAVE
LIKELY BEEN PARTLY RESPONSIBLE FOR THE SOMEWHAT CHAOTIC VISIBILITY
FIELD. WITH CONTINUED MOISTURE POOLING FROM ADVECTION AND
SNOW SUBLIMATION...ALONG WITH LIGHT WINDS IMMEDIATELY ALONG THE
BOUNDARY...WILL CONTINUE THAT ADVISORY AS IS UNTIL 3 PM.
AS THE SURFACE LOW MOVES INTO NORTH CENTRAL IN BY 4-5 PM...THE
SOMEWHAT DEEPER NORTHERLY FLOW IN THE LOW-LEVELS...ALONG WITH
NIGHTFALL SHOULD ADVANCE THE FREEZING LINE SOUTHWARD. FORCING FOR
PRECIP INTO TONIGHT LOOKS TO BE MAINLY DRIZZLE AS ANY APPRECIABLE
MOISTURE TRANSPORT SHIFTS SOUTHEAST AND THERE IS A LACK OF ANY
REAL SHORT WAVE IMPULSES PRESENTLY FORECAST. SOUNDINGS MARGINALLY
SUPPORTIVE OF DRIZZLE ARE MAINLY INDICATED IN THE SOUTHERN
FORECAST AREA. OVERALL NOT FEELING THAT A HEADLINE WILL BE
NEEDED...AND MORE SO HANDLED WITH AN SPS. IT IS POSSIBLE THE
CURRENT FREEZING RAIN ADVISORY IS EXTENDED UNTIL 6-7 PM TO ACCOUNT
FOR THE LATE AFTERNOON RUSH IF RADAR TRENDS AND REPORTS CONTINUE
TO INDICATE SHOWERS AND DRIZZLE OVER THE SUBFREEZING BOUNDARY
LAYER AS WE NEAR 3 PM.
MTF
355 AM CST...
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENETIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PRECIP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING IFR CIG/VSBY TRENDS.
* PRECIPITATION ENDING TIME AND POSSIBLE LIGHT FREEZING RAIN TODAY.
* WINDS BACKING NORTH THEN NORTHWEST.
LENNING
//DISCUSSION...UPDATED 18Z...
SO FAR AT MDW/ORD/GYY THE TEMPERATURES HAVE REMAINED ENOUGH ABOVE
FREEZING THAT ICE AT THE SFC HAS NOT BEEN A PROBLEM. DPA HAS BEEN
RIGHT ON THE LINE BUT STILL ABOVE FREEZING...WHILE RFD HAS BEEN
HAVING CONSIDERABLE ICE PROBLEMS. RADAR TRENDS SUGGEST ORD/MDW
PRECIP MAY END A BIT SOONER THAN PREVIOUSLY EXPECTED THIS
AFTERNOON...AND FCST SOUNDINGS SUGGEST INCOMING COLD AIR WOULD
PRODUCE ONLY A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE AT WORST.
AFTER A BREAK IN PRECIP OVERNIGHT INTO TOMORROW MORNING...THE
NEXT LOW PRESSURE SYSTEM BEGINS AFFECTING THE AREA. AS PRECIP
DEVELOPS TOWARD MIDDAY TOMORROW...AGAIN THE FREEZING LINE WILL LIE
VERY CLOSE TO THE TERMINALS. TAFS REFLECT THE MORE OPTIMISTIC VIEW
THAT ORD/MDW REMAIN ON THE LIQUID SIDE AT LEAST THROUGH THE
AFTERNOON.
IF PRECIP REMAINS MOSTLY LIQUID THEN CIG/VSBY AND WIND TRENDS WILL
BE THE BIGGER ISSUES. AM NOT SEEING MUCH EITHER IN THE
OBSERVATIONS OR IN FCST GUIDANCE TO SUGGEST CIGS WILL IMPROVE
ABOVE IFR THROUGH THE AFTERNOON...AND SOME POSSIBILITY EXISTS FOR
LIFR. VSBYS ARE IN SLIGHTLY BETTER SHAPE.
STILL THINK WINDS WILL BACK TO NORTHWEST BY THIS EVENING THEN
FLUCTUATE BETWEEN NNW AND NNW TONIGHT AND TOMORROW AS THE LOW
PRESSURE SYSTEMS TO OUR SOUTH MIGRATE THROUGH THE AREA.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW CONFIDENCE ABOUT EXACT CIG/VSBY TRENDS THIS AFTERNOON BUT
FAVOR MOSTLY IFR WITH OCCASIONAL LIFR CIGS AND VFR VSBYS.
* WINDS HAVE BEEN STEADY NNE BUT STILL MEDIUM TO HIGH CONFIDENCE
THAT TREND WILL VERY SOON BE MORE NORTHERLY THIS AFTERNOON.
* LOW CONFIDENCE ON HOW LOW CIGS GO OVERNIGHT.
* MEDIUM CONFIDENCE ON TIMING OF PRECIP TOMORROW BUT LOW
CONFIDENCE IN PRECIP TYPE TOMORROW AFTERNOON.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 7 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 7 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 PM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
257 PM CST FRI DEC 20 2013
.DISCUSSION...
1155 AM CST
HAVE CONTINUED ALL CURRENT HEADLINES AS IS INTO THIS AFTERNOON.
NO SIGNIFICANT CHANGES ARE AT LEAST PLANNED THIS AFTERNOON FOR THE
WINTER STORM WATCH THAT IS IN EFFECT FOR SATURDAY NIGHT INTO
SUNDAY. HOWEVER...WE CONTINUE TO ANALYZE THE POTENTIAL FOR
FREEZING RAIN TO THE SOUTH OF THE CURRENT WATCH...INCLUDING EVEN
DURING THE DAY SATURDAY. THIS MAY REQUIRE A WINTER WEATHER
HEADLINE.
WATER VAPOR SHOWS SOME RELATIVE DRYING MOVING OVER THE AREA IN
THIS DEEP SOUTHWEST MOIST PLUME AND THAT ALONG WITH JUST LESS
ASCENT IS LIKELY RESPONSIBLE FOR THE DIMINISHING SHOWER COVERAGE.
THIS TREND SHOULD SLOWLY CONTINUE ALTHOUGH PROFILES REMAIN AT
LEAST SUPPORTIVE OF DRIZZLE THROUGH THE AFTERNOON. THE FREEZING
LINE HAS MAINTAINED ITS GROUND THROUGH THE PAST SEVERAL HOURS AND
EXPECT VERY LITTLE CHANGE WITH THAT THROUGH MID AFTERNOON...HENCE
THE PRESERVING OF THE FREEZING RAIN ADVISORY.
WHILE VISIBILITY OBSERVATIONS OF DENSE FOG ARE FAR MORE SPOTTY IN
THE SOUTHERN CWA THAN THEY WERE THIS MORNING...THE SHOWERS HAVE
LIKELY BEEN PARTLY RESPONSIBLE FOR THE SOMEWHAT CHAOTIC VISIBILITY
FIELD. WITH CONTINUED MOISTURE POOLING FROM ADVECTION AND
SNOW SUBLIMATION...ALONG WITH LIGHT WINDS IMMEDIATELY ALONG THE
BOUNDARY...WILL CONTINUE THAT ADVISORY AS IS UNTIL 3 PM.
AS THE SURFACE LOW MOVES INTO NORTH CENTRAL IN BY 4-5 PM...THE
SOMEWHAT DEEPER NORTHERLY FLOW IN THE LOW-LEVELS...ALONG WITH
NIGHTFALL SHOULD ADVANCE THE FREEZING LINE SOUTHWARD. FORCING FOR
PRECIP INTO TONIGHT LOOKS TO BE MAINLY DRIZZLE AS ANY APPRECIABLE
MOISTURE TRANSPORT SHIFTS SOUTHEAST AND THERE IS A LACK OF ANY
REAL SHORT WAVE IMPULSES PRESENTLY FORECAST. SOUNDINGS MARGINALLY
SUPPORTIVE OF DRIZZLE ARE MAINLY INDICATED IN THE SOUTHERN
FORECAST AREA. OVERALL NOT FEELING THAT A HEADLINE WILL BE
NEEDED...AND MORE SO HANDLED WITH AN SPS. IT IS POSSIBLE THE
CURRENT FREEZING RAIN ADVISORY IS EXTENDED UNTIL 6-7 PM TO ACCOUNT
FOR THE LATE AFTERNOON RUSH IF RADAR TRENDS AND REPORTS CONTINUE
TO INDICATE SHOWERS AND DRIZZLE OVER THE SUBFREEZING BOUNDARY
LAYER AS WE NEAR 3 PM.
MTF
//PREV DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENETIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PRECIP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
.EXTENDED FORECAST PERIOD...FROM MONDAY MORNING THROUGH FRIDAY...
INCLUDING THE CHRISTMAS HOLIDAY...
UPDATED...300PM CST...
THE SENSIBLE WEATHER WILL QUIET CONSIDERABLY WITH THE MAIN FORECAST
CONCERNS FOCUSING ON TEMPERATURES AND THE CHANCE FOR SOME LIGHT
SNOW ON CHRISTMAS EVE AND EARLY CHRISTMAS DAY. THE GENERAL TREND
FOR THE EXTENDED FORECAST PERIOD WILL BE FOR MUCH BELOW NORMAL
TEMPERATURES WITH THE ONLY CHANCE FOR SOME LIGHT SNOW ON CHRISTMAS
EVE INTO CHRISTMAS DAY.
A HIGH AMPLITUDE LONGWAVE TROUGH IS EXPECTED TO CARVE OUT OVER THE
CNTRL CONUS WITH THE TROUGH AXIS EXTENDING FROM HUDSON BAY THROUGH
CENTRAL TEXAS. INITIALLY ON MONDAY...THE LOCAL AREA WILL SEE THE
TROUGH AXIS MOVING THROUGH THE AREA TRANSITIONING THE REGION FROM
RELATIVE WARM ADVECTION TO STRONG COLD ADVECTION. TEMPERATURES WILL
DROP OFF QUICKLY BY MONDAY MORNING...WITH LOWS EXPECTED TO DROP ONTO
THE SINGLE DIGITS WEST OF THE FOX VALLEY AND I-55 CORRIDOR. LOWS
OVER THE EASTERN PORTION OF THE FORECAST AREA SHOULD HANG IN THE
MIDDLE TO UPPER TEENS. AS THE LONGWAVE TROUGH CONTINUES TO THE ERN
CONUS MONDAY AND MONDAY NIGHT...WEAK UPPER RIDGING WILL BUILD ACROSS
THE UPPER MISSISSIPPI VALLEY...WITH THE AMPLITUDE OF THE UPPER LEVEL
PATTERN CONTINUING TO AMPLIFY. WITH DEEP LAYER FLOW REMAINING ON
THE NWLY FLOW SIDE OF THE UPPER RIDGE...TEMPERATURES WILL CONTINUE
TO DROP WITH LOWS TUESDAY MORNING BELOW ZERO OVER MUCH OF THE CWA...
GENERALLY WEST OF A LINE FROM WAUKEGAN TO PONTIAC...WITH THE
COLDEST AIR OVER THE ROCKFORD AREA WHERE TEMPS SHOULD BOTTOM OUT AT
-5F TO -10F. WIND CHILLS WILL BE A CONCERN AS WELL. WITH WINDS OF
5-10 KT LIKELY...WIND CHILLS WILL APPROACH THE -20F WIND CHILL
ADVISORY CRITERIA WEST OF THE FOX VALLEY AND I-55 CORRIDOR. BY
TUESDAY NIGHT...THE LONGER RANGE MODELS ARE ADVERTISING A PAIR OF
NORTHERN STREAM SHORTWAVES TRACKING ACROSS THE NRN PLAINS. THE
NRN-MOST WAVE...WHICH IS ALSO THE STRONGER OF THE PAIR...SHOULD
TRACK TO THE EAST...ACROSS THE UPPER GREAT LAKES WHILE THE MORE
SOUTHERLY...WEAKER WAVE DROPS THROUGH THE NRN PLAINS TO THE MIDDLE
MISSISSIPPI VALLEY. THIS THERE IS SOME DISCREPANCY AMONG THE LONGER
RANGE GUIDANCE ON THE SPEED OF PROGRESSION OF THIS WAVE...BUT THE
GENERAL CONSENSUS IS THAT THE WAVE WILL CROSS THE MIDDLE MISSISSIPPI
VALLEY...TRACKING OVER THE IL/WI BOARDER. FOLLOWING A PERIOD OF
STRONG COLD/DRY ADVECTION...THERE WILL BE LITTLE IN SITU MOISTURE
FOR THE SYSTEM TO WORK WITH AND WILL LARGELY HAVE TO RELY ON
DYNAMICS TO PRODUCE ANY PCPN. AT THIS POINT...ANTICIPATE THAT UPPER
DYNAMICS SHOULD BE STRONG ENOUGH TO PRODUCE AT LEAST SOME LIGHT SNOW
FOR LATE CHRISTMAS EVE INTO EARLY CHRISTMAS DAY. GIVEN THE LACK OF
DEEP LAYER MOISTURE OR ANY SIGNIFICANT LOW LEVEL MOISTURE TRANSPORT
AS FLOW THROUGH THE LOWER LEVELS SHOULD BE MORE WESTERLY AND UNABLE
TO TAP ANY GULF MOISTURE...ANY ACCUMULATIONS WILL LIKELY BE LIGHT.
A BRIEF PERIOD OF MORE WLY OR AT LEAST BROAD...FLAT TROUGHING SHOULD
COVER THE MIDWEST ON WEDNESDAY...ALLOWING FOR SOME MODERATION OF
TEMPERATURES ON WEDNESDAY AND THURSDAY...WITH HIGHS IN THE UPPER 20S
TO LOWER 30S ON WEDNESDAY AND UPPER TEENS TO MIDDLE 20S ON THURSDAY.
A REINFORCING SHOT OF COLD AIR ASSOCIATED WITH A STRONG NORTHERN
STREAM SHORTWAVE DIGGING INTO THE UPPER MISSISSIPPI VALLEY AND
SOUTHERN GREAT LAKES WILL BRING SUB-ZERO TEMPERATURES BACK TO MUCH
OF THE CWA FOR FRIDAY MORNING.
KREIN
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING IFR CIG/VSBY TRENDS.
* PRECIPITATION ENDING TIME AND POSSIBLE LIGHT FREEZING RAIN TODAY.
* WINDS BACKING NORTH THEN NORTHWEST.
LENNING
//DISCUSSION...UPDATED 18Z...
SO FAR AT MDW/ORD/GYY THE TEMPERATURES HAVE REMAINED ENOUGH ABOVE
FREEZING THAT ICE AT THE SFC HAS NOT BEEN A PROBLEM. DPA HAS BEEN
RIGHT ON THE LINE BUT STILL ABOVE FREEZING...WHILE RFD HAS BEEN
HAVING CONSIDERABLE ICE PROBLEMS. RADAR TRENDS SUGGEST ORD/MDW
PRECIP MAY END A BIT SOONER THAN PREVIOUSLY EXPECTED THIS
AFTERNOON...AND FCST SOUNDINGS SUGGEST INCOMING COLD AIR WOULD
PRODUCE ONLY A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE AT WORST.
AFTER A BREAK IN PRECIP OVERNIGHT INTO TOMORROW MORNING...THE
NEXT LOW PRESSURE SYSTEM BEGINS AFFECTING THE AREA. AS PRECIP
DEVELOPS TOWARD MIDDAY TOMORROW...AGAIN THE FREEZING LINE WILL LIE
VERY CLOSE TO THE TERMINALS. TAFS REFLECT THE MORE OPTIMISTIC VIEW
THAT ORD/MDW REMAIN ON THE LIQUID SIDE AT LEAST THROUGH THE
AFTERNOON.
IF PRECIP REMAINS MOSTLY LIQUID THEN CIG/VSBY AND WIND TRENDS WILL
BE THE BIGGER ISSUES. AM NOT SEEING MUCH EITHER IN THE
OBSERVATIONS OR IN FCST GUIDANCE TO SUGGEST CIGS WILL IMPROVE
ABOVE IFR THROUGH THE AFTERNOON...AND SOME POSSIBILITY EXISTS FOR
LIFR. VSBYS ARE IN SLIGHTLY BETTER SHAPE.
STILL THINK WINDS WILL BACK TO NORTHWEST BY THIS EVENING THEN
FLUCTUATE BETWEEN NNW AND NNW TONIGHT AND TOMORROW AS THE LOW
PRESSURE SYSTEMS TO OUR SOUTH MIGRATE THROUGH THE AREA.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW CONFIDENCE ABOUT EXACT CIG/VSBY TRENDS THIS AFTERNOON BUT
FAVOR MOSTLY IFR WITH OCCASIONAL LIFR CIGS AND VFR VSBYS.
* WINDS HAVE BEEN STEADY NNE BUT STILL MEDIUM TO HIGH CONFIDENCE
THAT TREND WILL VERY SOON BE MORE NORTHERLY THIS AFTERNOON.
* LOW CONFIDENCE ON HOW LOW CIGS GO OVERNIGHT.
* MEDIUM CONFIDENCE ON TIMING OF PRECIP TOMORROW BUT LOW
CONFIDENCE IN PRECIP TYPE TOMORROW AFTERNOON.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 7 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 7 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 PM FRIDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
218 PM CST FRI DEC 20 2013
.DISCUSSION...
1155 AM CST
HAVE CONTINUED ALL CURRENT HEADLINES AS IS INTO THIS AFTERNOON.
NO SIGNIFICANT CHANGES ARE AT LEAST PLANNED THIS AFTERNOON FOR THE
WINTER STORM WATCH THAT IS IN EFFECT FOR SATURDAY NIGHT INTO
SUNDAY. HOWEVER...WE CONTINUE TO ANALYZE THE POTENTIAL FOR
FREEZING RAIN TO THE SOUTH OF THE CURRENT WATCH...INCLUDING EVEN
DURING THE DAY SATURDAY. THIS MAY REQUIRE A WINTER WEATHER
HEADLINE.
WATER VAPOR SHOWS SOME RELATIVE DRYING MOVING OVER THE AREA IN
THIS DEEP SOUTHWEST MOIST PLUME AND THAT ALONG WITH JUST LESS
ASCENT IS LIKELY RESPONSIBLE FOR THE DIMINISHING SHOWER COVERAGE.
THIS TREND SHOULD SLOWLY CONTINUE ALTHOUGH PROFILES REMAIN AT
LEAST SUPPORTIVE OF DRIZZLE THROUGH THE AFTERNOON. THE FREEZING
LINE HAS MAINTAINED ITS GROUND THROUGH THE PAST SEVERAL HOURS AND
EXPECT VERY LITTLE CHANGE WITH THAT THROUGH MID AFTERNOON...HENCE
THE PRESERVING OF THE FREEZING RAIN ADVISORY.
WHILE VISIBILITY OBSERVATIONS OF DENSE FOG ARE FAR MORE SPOTTY IN
THE SOUTHERN CWA THAN THEY WERE THIS MORNING...THE SHOWERS HAVE
LIKELY BEEN PARTLY RESPONSIBLE FOR THE SOMEWHAT CHAOTIC VISIBILITY
FIELD. WITH CONTINUED MOISTURE POOLING FROM ADVECTION AND
SNOW SUBLIMATION...ALONG WITH LIGHT WINDS IMMEDIATELY ALONG THE
BOUNDARY...WILL CONTINUE THAT ADVISORY AS IS UNTIL 3 PM.
AS THE SURFACE LOW MOVES INTO NORTH CENTRAL IN BY 4-5 PM...THE
SOMEWHAT DEEPER NORTHERLY FLOW IN THE LOW-LEVELS...ALONG WITH
NIGHTFALL SHOULD ADVANCE THE FREEZING LINE SOUTHWARD. FORCING FOR
PRECIP INTO TONIGHT LOOKS TO BE MAINLY DRIZZLE AS ANY APPRECIABLE
MOISTURE TRANSPORT SHIFTS SOUTHEAST AND THERE IS A LACK OF ANY
REAL SHORT WAVE IMPULSES PRESENTLY FORECAST. SOUNDINGS MARGINALLY
SUPPORTIVE OF DRIZZLE ARE MAINLY INDICATED IN THE SOUTHERN
FORECAST AREA. OVERALL NOT FEELING THAT A HEADLINE WILL BE
NEEDED...AND MORE SO HANDLED WITH AN SPS. IT IS POSSIBLE THE
CURRENT FREEZING RAIN ADVISORY IS EXTENDED UNTIL 6-7 PM TO ACCOUNT
FOR THE LATE AFTERNOON RUSH IF RADAR TRENDS AND REPORTS CONTINUE
TO INDICATE SHOWERS AND DRIZZLE OVER THE SUBFREEZING BOUNDARY
LAYER AS WE NEAR 3 PM.
MTF
//PREV DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENETIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PRECIP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
MEDIUM AND LONG RANGE...MONDAY THROUGH THURSDAY...
MAIN CONCERNS BEYOND THIS WEEKEND ARE THE RETURN OF ARCTIC AIR AND
MUCH COLDER TEMPERATURES MONDAY-TUESDAY...AND THE POTENTIAL FOR A
LITTLE LIGHT SNOW CHRISTMAS EVE-CHRISTMAS DAY.
DEEP UPPER TROUGH TRAVERSING THE REGION MONDAY WITH FAIRLY
IMPRESSIVE SHORT WAVE ENERGY PASSING OVERHEAD. FORECAST SOUNDINGS
INDICATE SATURATION IN LOW LEVELS...WITH TEMPS NEAR -15C AS BOUNDARY
LAYER COOLS IN BLUSTERY COLD ADVECTION BEHIND DEPARTING WEEKEND LOW
PRESSURE SYSTEM. THIS SHOULD SUPPORT FLURRIES/LIGHT SNOW SHOWERS
ACROSS THE CWA INTO THE AFTERNOON HOURS. OF MORE IMPORTANCE THAN THE
POTENTIAL FOR LIGHT SNOW SHOWERS OR FLURRIES HOWEVER WILL BE THE
MUCH COLDER TEMPS AND WIND CHILLS AS ARCTIC AIR PLUNGES BACK INTO
THE REGION. TEMPS AT H8 FALL TO AROUND -16 C BY LATE AFTERNOON WITH
H9 TEMPS NEARLY SO...SUGGESTING SURFACE TEMPS MAY STRUGGLE TO RISE
ABOVE 10-15F AND WILL LIKELY FALL INTO THE SINGLE DIGITS ACROSS
NORTH CENTRAL IL AND WIND CHILLS IN THE NEGATIVE SINGLE DIGITS.
SURFACE HIGH PRESSURE RIDGE WILL BUILD ACROSS THE MISSISSIPPI VALLEY
AND INTO IL MONDAY NIGHT IN RESPONSE TO SUBSIDENCE BEHIND THE
DEPARTING UPPER TROUGH...WITH CLEARING SKIES...NEW SNOW COVER
ESPECIALLY FAR NORTHERN IL...AND DECREASING WINDS EXPECTED TO RESULT
IN STRONG RADIATIONAL COOLING. BOTH GFS AND ECMWF MOS DEPICT
SUB-ZERO LOWS ACROSS MUCH OF NORTHERN IL BY SUNRISE TUESDAY. SURFACE
HIGH PRESSURE RIDGE MOVES ACROSS THE AREA DURING THE DAY TUESDAY...
WITH WINDS BACKING TO THE SOUTH-SOUTHEAST DURING THE AFTERNOON AS
WARM ADVECTION DEVELOPS (ALOFT AT LEAST) IN ADVANCE OF A SHORT WAVE
EMERGING FROM THE PLAINS. MODERATION IN TEMPS LIMITED AT THE SURFACE
HOWEVER WITH VERY COLD START TO DAY AND STRONG INVERSION LIMITING
WARMING AT THE SURFACE WITH HIGHS IN THE TEENS/LOW 20S.
LONG RANGE GUIDANCE SIMILAR IN BRINGING SHORT WAVE TROUGH ACROSS
THE REGION DURING THE TUESDAY NIGHT/WEDNESDAY PERIOD AND ANOTHER
WEDNESDAY NIGHT/THURSDAY...THOUGH DIFFERENCES DO EXIST WITH
AMPLITUDE OF THESE INDIVIDUAL WAVES AND ASSOCIATED SURFACE
REFLECTIONS. THE ECMWF IS STRONGER/MORE AMPLIFIED WITH BOTH...
THOUGH AT THIS DISTANCE HAVE FOCUSED MAINLY ON SIMILARITIES BETWEEN
GUIDANCE. THIS YIELDS A LITTLE TEMPERATURE MODERATION CHRISTMAS EVE
AND CHRISTMAS DAY WITH A CHANCE OF SOME LIGHT SNOW...PERHAPS
0.5-1.0" BASED ON ROUGH QPF OUTPUT. LIGHT SNOW MAY LINGER ACROSS
THE EASTERN CWA CHRISTMAS NIGHT INTO THURSDAY WITH SURFACE COLD
FRONTAL TROUGH. AS MENTIONED...BRIEF MODERATION PRODUCES HIGHS IN
THE 20S/AROUND 30 FOR CHRISTMAS DAY THEN COLDER AIR LOOKS TO RETURN
THURSDAY BEHIND THE FRONT WITH TEMPS IN THE TEENS/LOW 20S.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING IFR CIG/VSBY TRENDS.
* PRECIPITATION ENDING TIME AND POSSIBLE LIGHT FREEZING RAIN TODAY.
* WINDS BACKING NORTH THEN NORTHWEST.
LENNING
//DISCUSSION...UPDATED 18Z...
SO FAR AT MDW/ORD/GYY THE TEMPERATURES HAVE REMAINED ENOUGH ABOVE
FREEZING THAT ICE AT THE SFC HAS NOT BEEN A PROBLEM. DPA HAS BEEN
RIGHT ON THE LINE BUT STILL ABOVE FREEZING...WHILE RFD HAS BEEN
HAVING CONSIDERABLE ICE PROBLEMS. RADAR TRENDS SUGGEST ORD/MDW
PRECIP MAY END A BIT SOONER THAN PREVIOUSLY EXPECTED THIS
AFTERNOON...AND FCST SOUNDINGS SUGGEST INCOMING COLD AIR WOULD
PRODUCE ONLY A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE AT WORST.
AFTER A BREAK IN PRECIP OVERNIGHT INTO TOMORROW MORNING...THE
NEXT LOW PRESSURE SYSTEM BEGINS AFFECTING THE AREA. AS PRECIP
DEVELOPS TOWARD MIDDAY TOMORROW...AGAIN THE FREEZING LINE WILL LIE
VERY CLOSE TO THE TERMINALS. TAFS REFLECT THE MORE OPTIMISTIC VIEW
THAT ORD/MDW REMAIN ON THE LIQUID SIDE AT LEAST THROUGH THE
AFTERNOON.
IF PRECIP REMAINS MOSTLY LIQUID THEN CIG/VSBY AND WIND TRENDS WILL
BE THE BIGGER ISSUES. AM NOT SEEING MUCH EITHER IN THE
OBSERVATIONS OR IN FCST GUIDANCE TO SUGGEST CIGS WILL IMPROVE
ABOVE IFR THROUGH THE AFTERNOON...AND SOME POSSIBILITY EXISTS FOR
LIFR. VSBYS ARE IN SLIGHTLY BETTER SHAPE.
STILL THINK WINDS WILL BACK TO NORTHWEST BY THIS EVENING THEN
FLUCTUATE BETWEEN NNW AND NNW TONIGHT AND TOMORROW AS THE LOW
PRESSURE SYSTEMS TO OUR SOUTH MIGRATE THROUGH THE AREA.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW CONFIDENCE ABOUT EXACT CIG/VSBY TRENDS THIS AFTERNOON BUT
FAVOR MOSTLY IFR WITH OCCASIONAL LIFR CIGS AND VFR VSBYS.
* WINDS HAVE BEEN STEADY NNE BUT STILL MEDIUM TO HIGH CONFIDENCE
THAT TREND WILL VERY SOON BE MORE NORTHERLY THIS AFTERNOON.
* LOW CONFIDENCE ON HOW LOW CIGS GO OVERNIGHT.
* MEDIUM CONFIDENCE ON TIMING OF PRECIP TOMORROW BUT LOW
CONFIDENCE IN PRECIP TYPE TOMORROW AFTERNOON.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
218 PM...LOW PRESSURE OVER CENTRAL ILLINOIS WILL MOVE NORTHEAST
ACROSS THE EASTERN LAKES TONIGHT AS IT SLOWLY WEAKENS AS WEAK HIGH
PRESSURE OVER THE UPPER MIDWEST IS ABSORBED BY STRONGER HIGH
PRESSURE MOVING ACROSS SOUTHERN CANADA SATURDAY AND SATURDAY
NIGHT. THE GRADIENT WILL SLOWLY WEAKEN TONIGHT WITH SPEEDS IN THE
10-15 KT RANGE BY MORNING. NEW LOW PRESSURE WILL DEVELOP OVER
TEXAS TONIGHT AND MOVE NORTHEAST TO NORTHERN INDIANA BY SUNDAY
MORNING. AS THIS LOW APPROACHES THE LAKES REGION...IT WILL DEEPEN
AND THE GRADIENT WILL TIGHTEN BETWEEN THE STRONGER HIGH ACROSS
SOUTHERN CANADA. NORTHEAST WINDS WILL STEADILY INCREASE SATURDAY
EVENING WITH 30 KTS EXPECTED. DEPENDING ON THE EXACT STRENGTH AND
TRACK OF THIS LOW...ITS POSSIBLE THERE COULD BE A PERIOD OF LOW
END GALES BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THIS FORECAST. A
TROUGH OF LOW PRESSURE WILL THEN LINGER ACROSS THE WESTERN LAKES
REGION SUNDAY NIGHT WITH NORTHERLY WINDS SHIFTING NORTHWESTERLY.
STRONG HIGH PRESSURE WILL BUILD ACROSS THE PLAINS SUNDAY AND
SUNDAY NIGHT AND THEN SHIFT EAST ACROSS THE LAKES REGION MONDAY
NIGHT AND TUESDAY. THERE IS A POTENTIAL FOR A PERIOD OF STRONG
WINDS AHEAD OF THE HIGH...IN THE MONDAY/MONDAY NIGHT TIME PERIOD.
BUT CONFIDENCE REGARDING SPECIFICS DURING THIS TIME PERIOD REMAIN
LOW. CMS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 7 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 7 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS
UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 PM FRIDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
213 PM CST FRI DEC 20 2013
.DISCUSSION...
1155 AM CST
HAVE CONTINUED ALL CURRENT HEADLINES AS IS INTO THIS AFTERNOON.
NO SIGNIFICANT CHANGES ARE AT LEAST PLANNED THIS AFTERNOON FOR THE
WINTER STORM WATCH THAT IS IN EFFECT FOR SATURDAY NIGHT INTO
SUNDAY. HOWEVER...WE CONTINUE TO ANALYZE THE POTENTIAL FOR
FREEZING RAIN TO THE SOUTH OF THE CURRENT WATCH...INCLUDING EVEN
DURING THE DAY SATURDAY. THIS MAY REQUIRE A WINTER WEATHER
HEADLINE.
WATER VAPOR SHOWS SOME RELATIVE DRYING MOVING OVER THE AREA IN
THIS DEEP SOUTHWEST MOIST PLUME AND THAT ALONG WITH JUST LESS
ASCENT IS LIKELY RESPONSIBLE FOR THE DIMINISHING SHOWER COVERAGE.
THIS TREND SHOULD SLOWLY CONTINUE ALTHOUGH PROFILES REMAIN AT
LEAST SUPPORTIVE OF DRIZZLE THROUGH THE AFTERNOON. THE FREEZING
LINE HAS MAINTAINED ITS GROUND THROUGH THE PAST SEVERAL HOURS AND
EXPECT VERY LITTLE CHANGE WITH THAT THROUGH MID AFTERNOON...HENCE
THE PRESERVING OF THE FREEZING RAIN ADVISORY.
WHILE VISIBILITY OBSERVATIONS OF DENSE FOG ARE FAR MORE SPOTTY IN
THE SOUTHERN CWA THAN THEY WERE THIS MORNING...THE SHOWERS HAVE
LIKELY BEEN PARTLY RESPONSIBLE FOR THE SOMEWHAT CHAOTIC VISIBILITY
FIELD. WITH CONTINUED MOISTURE POOLING FROM ADVECTION AND
SNOW SUBLIMATION...ALONG WITH LIGHT WINDS IMMEDIATELY ALONG THE
BOUNDARY...WILL CONTINUE THAT ADVISORY AS IS UNTIL 3 PM.
AS THE SURFACE LOW MOVES INTO NORTH CENTRAL IN BY 4-5 PM...THE
SOMEWHAT DEEPER NORTHERLY FLOW IN THE LOW-LEVELS...ALONG WITH
NIGHTFALL SHOULD ADVANCE THE FREEZING LINE SOUTHWARD. FORCING FOR
PRECIP INTO TONIGHT LOOKS TO BE MAINLY DRIZZLE AS ANY APPRECIABLE
MOISTURE TRANSPORT SHIFTS SOUTHEAST AND THERE IS A LACK OF ANY
REAL SHORT WAVE IMPULSES PRESENTLY FORECAST. SOUNDINGS MARGINALLY
SUPPORTIVE OF DRIZZLE ARE MAINLY INDICATED IN THE SOUTHERN
FORECAST AREA. OVERALL NOT FEELING THAT A HEADLINE WILL BE
NEEDED...AND MORE SO HANDLED WITH AN SPS. IT IS POSSIBLE THE
CURRENT FREEZING RAIN ADVISORY IS EXTENDED UNTIL 6-7 PM TO ACCOUNT
FOR THE LATE AFTERNOON RUSH IF RADAR TRENDS AND REPORTS CONTINUE
TO INDICATE SHOWERS AND DRIZZLE OVER THE SUBFREEZING BOUNDARY
LAYER AS WE NEAR 3 PM.
MTF
//PREV DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENETIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PRECIP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
MEDIUM AND LONG RANGE...MONDAY THROUGH THURSDAY...
MAIN CONCERNS BEYOND THIS WEEKEND ARE THE RETURN OF ARCTIC AIR AND
MUCH COLDER TEMPERATURES MONDAY-TUESDAY...AND THE POTENTIAL FOR A
LITTLE LIGHT SNOW CHRISTMAS EVE-CHRISTMAS DAY.
DEEP UPPER TROUGH TRAVERSING THE REGION MONDAY WITH FAIRLY
IMPRESSIVE SHORT WAVE ENERGY PASSING OVERHEAD. FORECAST SOUNDINGS
INDICATE SATURATION IN LOW LEVELS...WITH TEMPS NEAR -15C AS BOUNDARY
LAYER COOLS IN BLUSTERY COLD ADVECTION BEHIND DEPARTING WEEKEND LOW
PRESSURE SYSTEM. THIS SHOULD SUPPORT FLURRIES/LIGHT SNOW SHOWERS
ACROSS THE CWA INTO THE AFTERNOON HOURS. OF MORE IMPORTANCE THAN THE
POTENTIAL FOR LIGHT SNOW SHOWERS OR FLURRIES HOWEVER WILL BE THE
MUCH COLDER TEMPS AND WIND CHILLS AS ARCTIC AIR PLUNGES BACK INTO
THE REGION. TEMPS AT H8 FALL TO AROUND -16 C BY LATE AFTERNOON WITH
H9 TEMPS NEARLY SO...SUGGESTING SURFACE TEMPS MAY STRUGGLE TO RISE
ABOVE 10-15F AND WILL LIKELY FALL INTO THE SINGLE DIGITS ACROSS
NORTH CENTRAL IL AND WIND CHILLS IN THE NEGATIVE SINGLE DIGITS.
SURFACE HIGH PRESSURE RIDGE WILL BUILD ACROSS THE MISSISSIPPI VALLEY
AND INTO IL MONDAY NIGHT IN RESPONSE TO SUBSIDENCE BEHIND THE
DEPARTING UPPER TROUGH...WITH CLEARING SKIES...NEW SNOW COVER
ESPECIALLY FAR NORTHERN IL...AND DECREASING WINDS EXPECTED TO RESULT
IN STRONG RADIATIONAL COOLING. BOTH GFS AND ECMWF MOS DEPICT
SUB-ZERO LOWS ACROSS MUCH OF NORTHERN IL BY SUNRISE TUESDAY. SURFACE
HIGH PRESSURE RIDGE MOVES ACROSS THE AREA DURING THE DAY TUESDAY...
WITH WINDS BACKING TO THE SOUTH-SOUTHEAST DURING THE AFTERNOON AS
WARM ADVECTION DEVELOPS (ALOFT AT LEAST) IN ADVANCE OF A SHORT WAVE
EMERGING FROM THE PLAINS. MODERATION IN TEMPS LIMITED AT THE SURFACE
HOWEVER WITH VERY COLD START TO DAY AND STRONG INVERSION LIMITING
WARMING AT THE SURFACE WITH HIGHS IN THE TEENS/LOW 20S.
LONG RANGE GUIDANCE SIMILAR IN BRINGING SHORT WAVE TROUGH ACROSS
THE REGION DURING THE TUESDAY NIGHT/WEDNESDAY PERIOD AND ANOTHER
WEDNESDAY NIGHT/THURSDAY...THOUGH DIFFERENCES DO EXIST WITH
AMPLITUDE OF THESE INDIVIDUAL WAVES AND ASSOCIATED SURFACE
REFLECTIONS. THE ECMWF IS STRONGER/MORE AMPLIFIED WITH BOTH...
THOUGH AT THIS DISTANCE HAVE FOCUSED MAINLY ON SIMILARITIES BETWEEN
GUIDANCE. THIS YIELDS A LITTLE TEMPERATURE MODERATION CHRISTMAS EVE
AND CHRISTMAS DAY WITH A CHANCE OF SOME LIGHT SNOW...PERHAPS
0.5-1.0" BASED ON ROUGH QPF OUTPUT. LIGHT SNOW MAY LINGER ACROSS
THE EASTERN CWA CHRISTMAS NIGHT INTO THURSDAY WITH SURFACE COLD
FRONTAL TROUGH. AS MENTIONED...BRIEF MODERATION PRODUCES HIGHS IN
THE 20S/AROUND 30 FOR CHRISTMAS DAY THEN COLDER AIR LOOKS TO RETURN
THURSDAY BEHIND THE FRONT WITH TEMPS IN THE TEENS/LOW 20S.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* ONGOING IFR CIG/VSBY TRENDS.
* PRECIPITATION ENDING TIME AND POSSIBLE LIGHT FREEZING RAIN TODAY.
* WINDS BACKING NORTH THEN NORTHWEST.
LENNING
//DISCUSSION...UPDATED 18Z...
SO FAR AT MDW/ORD/GYY THE TEMPERATURES HAVE REMAINED ENOUGH ABOVE
FREEZING THAT ICE AT THE SFC HAS NOT BEEN A PROBLEM. DPA HAS BEEN
RIGHT ON THE LINE BUT STILL ABOVE FREEZING...WHILE RFD HAS BEEN
HAVING CONSIDERABLE ICE PROBLEMS. RADAR TRENDS SUGGEST ORD/MDW
PRECIP MAY END A BIT SOONER THAN PREVIOUSLY EXPECTED THIS
AFTERNOON...AND FCST SOUNDINGS SUGGEST INCOMING COLD AIR WOULD
PRODUCE ONLY A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE AT WORST.
AFTER A BREAK IN PRECIP OVERNIGHT INTO TOMORROW MORNING...THE
NEXT LOW PRESSURE SYSTEM BEGINS AFFECTING THE AREA. AS PRECIP
DEVELOPS TOWARD MIDDAY TOMORROW...AGAIN THE FREEZING LINE WILL LIE
VERY CLOSE TO THE TERMINALS. TAFS REFLECT THE MORE OPTIMISTIC VIEW
THAT ORD/MDW REMAIN ON THE LIQUID SIDE AT LEAST THROUGH THE
AFTERNOON.
IF PRECIP REMAINS MOSTLY LIQUID THEN CIG/VSBY AND WIND TRENDS WILL
BE THE BIGGER ISSUES. AM NOT SEEING MUCH EITHER IN THE
OBSERVATIONS OR IN FCST GUIDANCE TO SUGGEST CIGS WILL IMPROVE
ABOVE IFR THROUGH THE AFTERNOON...AND SOME POSSIBILITY EXISTS FOR
LIFR. VSBYS ARE IN SLIGHTLY BETTER SHAPE.
STILL THINK WINDS WILL BACK TO NORTHWEST BY THIS EVENING THEN
FLUCTUATE BETWEEN NNW AND NNW TONIGHT AND TOMORROW AS THE LOW
PRESSURE SYSTEMS TO OUR SOUTH MIGRATE THROUGH THE AREA.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* LOW CONFIDENCE ABOUT EXACT CIG/VSBY TRENDS THIS AFTERNOON BUT
FAVOR MOSTLY IFR WITH OCCASIONAL LIFR CIGS AND VFR VSBYS.
* WINDS HAVE BEEN STEADY NNE BUT STILL MEDIUM TO HIGH CONFIDENCE
THAT TREND WILL VERY SOON BE MORE NORTHERLY THIS AFTERNOON.
* LOW CONFIDENCE ON HOW LOW CIGS GO OVERNIGHT.
* MEDIUM CONFIDENCE ON TIMING OF PRECIP TOMORROW BUT LOW
CONFIDENCE IN PRECIP TYPE TOMORROW AFTERNOON.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
301 AM CST
LOW PRESSURE CENTERED OVER NORTH-CENTRAL OKLAHOMA WILL TRACK
NORTHEAST ALONG A FRONTAL BOUNDARY WHICH EXTENDS NORTHEAST INTO
NORTHERN INDIANA AND EASTWARD ACROSS LAKE ERIE AND ONTARIO.
MEANWHILE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE LITTLE
THROUGH THE DAY. THE STRONGEST PRESSURE GRADIENT IS STARTING TO SET
UP EARLY THIS MORNING AND WILL LIKELY RESULT IN AN INCREASE IN
NORTHEAST WINDS ACROSS MUCH OF THE LAKE THROUGH MID MORNING BEFORE
THE PRESSURE GRADIENT EASES. SPEEDS MAY PUSH 30 KT FOR A TIME
THROUGH MID OR LATE MORNING...ESPECIALLY ACROSS CENTRAL SECTIONS OF
THE LAKE. THE LOW WILL PASS SOUTH OF THE LAKE LATER THIS AFTERNOON
AND BEGIN TO WEAKEN WITH THE HIGH WEAKENING AS WELL. ANOTHER SURFACE
LOW WILL DEVELOP OVER THE ARKLATEX SATURDAY AND LIFT NORTHEAST TO
NORTHERN OHIO BY SUNDAY AFTERNOON. A VERY STRONG HIGH WILL THEN
DEVELOP SOUTHWARD INTO THE NORTHERN PLAINS AS THE LOW MOVES INTO NEW
ENGLAND SUNDAY NIGHT. THIS WILL LEAVE LAKE MICHIGAN IN THE PRESSURE
GRADIENT BETWEEN THE TWO SYSTEMS SATURDAY NIGHT AND SUNDAY WITH
COLDER AIR SPILLING ACROSS THE LAKE AS WELL. THIS WILL SET THE STAGE
FOR ANOTHER ROUND OF STRONG WINDS WHICH WILL START OUT NORTHEAST
THEN SHIFT NORTH-NORTHWEST AND EASE UP LATE SUNDAY AFTERNOON. THE
HIGH WILL PASS SOUTH OF THE LAKE TUESDAY BEFORE LOW PRESSURE TRACKS
SOUTHEAST ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THIS
SHOULD LEAD TO ANOTHER PERIOD OF INCREASED WINDS...THIS TIME FROM
THE SOUTH AND SOUTHWEST WEDNESDAY. WILL KEEP SPEEDS BELOW GALE FORCE
THROUGH THE PERIOD BUT WILL NEED TO MONITOR FOR SHORT WINDOWS OF
GALE FORCE WINDS SATURDAY NIGHT AND SUNDAY MORNING...AND AGAIN EARLY
WEDNESDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 7 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 7 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 PM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1158 AM CST FRI DEC 20 2013
.DISCUSSION...
1155 AM CST
HAVE CONTINUED ALL CURRENT HEADLINES AS IS INTO THIS AFTERNOON.
NO SIGNIFICANT CHANGES ARE AT LEAST PLANNED THIS AFTERNOON FOR THE
WINTER STORM WATCH THAT IS IN EFFECT FOR SATURDAY NIGHT INTO
SUNDAY. HOWEVER...WE CONTINUE TO ANALYZE THE POTENTIAL FOR
FREEZING RAIN TO THE SOUTH OF THE CURRENT WATCH...INCLUDING EVEN
DURING THE DAY SATURDAY. THIS MAY REQUIRE A WINTER WEATHER
HEADLINE.
WATER VAPOR SHOWS SOME RELATIVE DRYING MOVING OVER THE AREA IN
THIS DEEP SOUTHWEST MOIST PLUME AND THAT ALONG WITH JUST LESS
ASCENT IS LIKELY RESPONSIBLE FOR THE DIMINISHING SHOWER COVERAGE.
THIS TREND SHOULD SLOWLY CONTINUE ALTHOUGH PROFILES REMAIN AT
LEAST SUPPORTIVE OF DRIZZLE THROUGH THE AFTERNOON. THE FREEZING
LINE HAS MAINTAINED ITS GROUND THROUGH THE PAST SEVERAL HOURS AND
EXPECT VERY LITTLE CHANGE WITH THAT THROUGH MID AFTERNOON...HENCE
THE PRESERVING OF THE FREEZING RAIN ADVISORY.
WHILE VISIBILITY OBSERVATIONS OF DENSE FOG ARE FAR MORE SPOTTY IN
THE SOUTHERN CWA THAN THEY WERE THIS MORNING...THE SHOWERS HAVE
LIKELY BEEN PARTLY RESPONSIBLE FOR THE SOMEWHAT CHAOTIC VISIBILITY
FIELD. WITH CONTINUED MOISTURE POOLING FROM ADVECTION AND
SNOW SUBLIMATION...ALONG WITH LIGHT WINDS IMMEDIATELY ALONG THE
BOUNDARY...WILL CONTINUE THAT ADVISORY AS IS UNTIL 3 PM.
AS THE SURFACE LOW MOVES INTO NORTH CENTRAL IN BY 4-5 PM...THE
SOMEWHAT DEEPER NORTHERLY FLOW IN THE LOW-LEVELS...ALONG WITH
NIGHTFALL SHOULD ADVANCE THE FREEZING LINE SOUTHWARD. FORCING FOR
PRECIP INTO TONIGHT LOOKS TO BE MAINLY DRIZZLE AS ANY APPRECIABLE
MOISTURE TRANSPORT SHIFTS SOUTHEAST AND THERE IS A LACK OF ANY
REAL SHORT WAVE IMPULSES PRESENTLY FORECAST. SOUNDINGS MARGINALLY
SUPPORTIVE OF DRIZZLE ARE MAINLY INDICATED IN THE SOUTHERN
FORECAST AREA. OVERALL NOT FEELING THAT A HEADLINE WILL BE
NEEDED...AND MORE SO HANDLED WITH AN SPS. IT IS POSSIBLE THE
CURRENT FREEZING RAIN ADVISORY IS EXTENDED UNTIL 6-7 PM TO ACCOUNT
FOR THE LATE AFTERNOON RUSH IF RADAR TRENDS AND REPORTS CONTINUE
TO INDICATE SHOWERS AND DRIZZLE OVER THE SUBFREEZING BOUNDARY
LAYER AS WE NEAR 3 PM.
MTF
//PREV DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENETIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PRECIP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
MEDIUM AND LONG RANGE...MONDAY THROUGH THURSDAY...
MAIN CONCERNS BEYOND THIS WEEKEND ARE THE RETURN OF ARCTIC AIR AND
MUCH COLDER TEMPERATURES MONDAY-TUESDAY...AND THE POTENTIAL FOR A
LITTLE LIGHT SNOW CHRISTMAS EVE-CHRISTMAS DAY.
DEEP UPPER TROUGH TRAVERSING THE REGION MONDAY WITH FAIRLY
IMPRESSIVE SHORT WAVE ENERGY PASSING OVERHEAD. FORECAST SOUNDINGS
INDICATE SATURATION IN LOW LEVELS...WITH TEMPS NEAR -15C AS BOUNDARY
LAYER COOLS IN BLUSTERY COLD ADVECTION BEHIND DEPARTING WEEKEND LOW
PRESSURE SYSTEM. THIS SHOULD SUPPORT FLURRIES/LIGHT SNOW SHOWERS
ACROSS THE CWA INTO THE AFTERNOON HOURS. OF MORE IMPORTANCE THAN THE
POTENTIAL FOR LIGHT SNOW SHOWERS OR FLURRIES HOWEVER WILL BE THE
MUCH COLDER TEMPS AND WIND CHILLS AS ARCTIC AIR PLUNGES BACK INTO
THE REGION. TEMPS AT H8 FALL TO AROUND -16 C BY LATE AFTERNOON WITH
H9 TEMPS NEARLY SO...SUGGESTING SURFACE TEMPS MAY STRUGGLE TO RISE
ABOVE 10-15F AND WILL LIKELY FALL INTO THE SINGLE DIGITS ACROSS
NORTH CENTRAL IL AND WIND CHILLS IN THE NEGATIVE SINGLE DIGITS.
SURFACE HIGH PRESSURE RIDGE WILL BUILD ACROSS THE MISSISSIPPI VALLEY
AND INTO IL MONDAY NIGHT IN RESPONSE TO SUBSIDENCE BEHIND THE
DEPARTING UPPER TROUGH...WITH CLEARING SKIES...NEW SNOW COVER
ESPECIALLY FAR NORTHERN IL...AND DECREASING WINDS EXPECTED TO RESULT
IN STRONG RADIATIONAL COOLING. BOTH GFS AND ECMWF MOS DEPICT
SUB-ZERO LOWS ACROSS MUCH OF NORTHERN IL BY SUNRISE TUESDAY. SURFACE
HIGH PRESSURE RIDGE MOVES ACROSS THE AREA DURING THE DAY TUESDAY...
WITH WINDS BACKING TO THE SOUTH-SOUTHEAST DURING THE AFTERNOON AS
WARM ADVECTION DEVELOPS (ALOFT AT LEAST) IN ADVANCE OF A SHORT WAVE
EMERGING FROM THE PLAINS. MODERATION IN TEMPS LIMITED AT THE SURFACE
HOWEVER WITH VERY COLD START TO DAY AND STRONG INVERSION LIMITING
WARMING AT THE SURFACE WITH HIGHS IN THE TEENS/LOW 20S.
LONG RANGE GUIDANCE SIMILAR IN BRINGING SHORT WAVE TROUGH ACROSS
THE REGION DURING THE TUESDAY NIGHT/WEDNESDAY PERIOD AND ANOTHER
WEDNESDAY NIGHT/THURSDAY...THOUGH DIFFERENCES DO EXIST WITH
AMPLITUDE OF THESE INDIVIDUAL WAVES AND ASSOCIATED SURFACE
REFLECTIONS. THE ECMWF IS STRONGER/MORE AMPLIFIED WITH BOTH...
THOUGH AT THIS DISTANCE HAVE FOCUSED MAINLY ON SIMILARITIES BETWEEN
GUIDANCE. THIS YIELDS A LITTLE TEMPERATURE MODERATION CHRISTMAS EVE
AND CHRISTMAS DAY WITH A CHANCE OF SOME LIGHT SNOW...PERHAPS
0.5-1.0" BASED ON ROUGH QPF OUTPUT. LIGHT SNOW MAY LINGER ACROSS
THE EASTERN CWA CHRISTMAS NIGHT INTO THURSDAY WITH SURFACE COLD
FRONTAL TROUGH. AS MENTIONED...BRIEF MODERATION PRODUCES HIGHS IN
THE 20S/AROUND 30 FOR CHRISTMAS DAY THEN COLDER AIR LOOKS TO RETURN
THURSDAY BEHIND THE FRONT WITH TEMPS IN THE TEENS/LOW 20S.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* IFR CIG/VSBY TRENDS.
* PRECIPITATION ENDING TIME AND POSSIBLE LIGHT FREEZING RAIN TODAY.
* WINDS BACKING NORTH THEN NORTHWEST.
LENNING
//DISCUSSION...UPDATED 18Z...
SO FAR AT MDW/ORD/GYY THE TEMPERATURES HAVE REMAINED ENOUGH ABOVE
FREEZING THAT ICE AT THE SFC HAS NOT BEEN A PROBLEM. DPA HAS BEEN
RIGHT ON THE LINE BUT STILL ABOVE FREEZING...WHILE RFD HAS BEEN
HAVING CONSIDERABLE ICE PROBLEMS. RADAR TRENDS SUGGEST ORD/MDW
PRECIP MAY END A BIT SOONER THAN PREVIOUSLY EXPECTED THIS
AFTERNOON...AND FCST SOUNDINGS SUGGEST INCOMING COLD AIR WOULD
PRODUCE ONLY A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE AT WORST.
AFTER A BREAK IN PRECIP OVERNIGHT INTO TOMORROW MORNING...THE
NEXT LOW PRESSURE SYSTEM BEGINS AFFECTING THE AREA. AS PRECIP
DEVELOPS TOWARD MIDDAY TOMORROW...AGAIN THE FREEZING LINE WILL LIE
VERY CLOSE TO THE TERMINALS. TAFS REFLECT THE MORE OPTIMISTIC VIEW
THAT ORD/MDW REMAIN ON THE LIQUID SIDE AT LEAST THROUGH THE
AFTERNOON.
IF PRECIP REMAINS MOSTLY LIQUID THEN CIG/VSBY AND WIND TRENDS WILL
BE THE BIGGER ISSUES. AM NOT SEEING MUCH EITHER IN THE
OBSERVATIONS OR IN FCST GUIDANCE TO SUGGEST CIGS WILL IMPROVE
ABOVE IFR THROUGH THE AFTERNOON...AND SOME POSSIBILITY EXISTS FOR
LIFR. VSBYS ARE IN SLIGHTLY BETTER SHAPE.
STILL THINK WINDS WILL BACK TO NORTHWEST BY THIS EVENING THEN
FLUCTUATE BETWEEN NNW AND NNW TONIGHT AND TOMORROW AS THE LOW
PRESSURE SYSTEMS TO OUR SOUTH MIGRATE THROUGH THE AREA.
LENNING
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN IFR CIGS CONTINUING. LOW CONFIDENCE IN HOW
THEY CHANGE AFTER PRECIP ENDS THIS AFTERNOON.
* HIGH CONFIDENCE IN MVFR OR BETTER VSBY TODAY. LOW CONFIDENCE IT
REMAINS VFR AS IN LATEST OBS.
* HIGH CONFIDENCE IN WIND BACKING TO NORTHWEST...MEDIUM CONFIDENCE
ON TIMING.
* HIGH CONFIDENCE IN LIGHT RAIN/DRIZZLE CONTINUING THROUGH EARLY
AFTERNOON. LOW CONFIDENCE IN POTENTIAL FOR -FZRA/FZDZ THIS
AFTERNOON.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
301 AM CST
LOW PRESSURE CENTERED OVER NORTH-CENTRAL OKLAHOMA WILL TRACK
NORTHEAST ALONG A FRONTAL BOUNDARY WHICH EXTENDS NORTHEAST INTO
NORTHERN INDIANA AND EASTWARD ACROSS LAKE ERIE AND ONTARIO.
MEANWHILE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE LITTLE
THROUGH THE DAY. THE STRONGEST PRESSURE GRADIENT IS STARTING TO SET
UP EARLY THIS MORNING AND WILL LIKELY RESULT IN AN INCREASE IN
NORTHEAST WINDS ACROSS MUCH OF THE LAKE THROUGH MID MORNING BEFORE
THE PRESSURE GRADIENT EASES. SPEEDS MAY PUSH 30 KT FOR A TIME
THROUGH MID OR LATE MORNING...ESPECIALLY ACROSS CENTRAL SECTIONS OF
THE LAKE. THE LOW WILL PASS SOUTH OF THE LAKE LATER THIS AFTERNOON
AND BEGIN TO WEAKEN WITH THE HIGH WEAKENING AS WELL. ANOTHER SURFACE
LOW WILL DEVELOP OVER THE ARKLATEX SATURDAY AND LIFT NORTHEAST TO
NORTHERN OHIO BY SUNDAY AFTERNOON. A VERY STRONG HIGH WILL THEN
DEVELOP SOUTHWARD INTO THE NORTHERN PLAINS AS THE LOW MOVES INTO NEW
ENGLAND SUNDAY NIGHT. THIS WILL LEAVE LAKE MICHIGAN IN THE PRESSURE
GRADIENT BETWEEN THE TWO SYSTEMS SATURDAY NIGHT AND SUNDAY WITH
COLDER AIR SPILLING ACROSS THE LAKE AS WELL. THIS WILL SET THE STAGE
FOR ANOTHER ROUND OF STRONG WINDS WHICH WILL START OUT NORTHEAST
THEN SHIFT NORTH-NORTHWEST AND EASE UP LATE SUNDAY AFTERNOON. THE
HIGH WILL PASS SOUTH OF THE LAKE TUESDAY BEFORE LOW PRESSURE TRACKS
SOUTHEAST ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THIS
SHOULD LEAD TO ANOTHER PERIOD OF INCREASED WINDS...THIS TIME FROM
THE SOUTH AND SOUTHWEST WEDNESDAY. WILL KEEP SPEEDS BELOW GALE FORCE
THROUGH THE PERIOD BUT WILL NEED TO MONITOR FOR SHORT WINDOWS OF
GALE FORCE WINDS SATURDAY NIGHT AND SUNDAY MORNING...AND AGAIN EARLY
WEDNESDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 3 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 3 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...NOON SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 3
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...NOON SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 PM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
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WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1040 AM CST FRI DEC 20 2013
.DISCUSSION...
805 AM CST
HAVE EXPANDED THE DENSE FOG ADVISORY TO INCLUDE AREAS SOUTH OF A
PONTIAC TO VALPARAISO LINE. HAVE RECEIVED MULTIPLE REPORTS OF
DENSE FOG ALONG THE SYNOPTIC BOUNDARY...WHICH IS PRACTICALLY
STATIONARY AS THE 1006MB SFC LOW NEAR QUINCY EASES ITS WAY
NORTHEAST. GOOD POOLING OF MOISTURE AND LIGHT WINDS ALONG THIS
SHOULD CONTINUE TO ALLOW FOR DENSE FOG THROUGH 12P-3P...UNTIL THE
LOW LIFTS THROUGH THE AREA. THE RAP AND HRRR FOR THE MOST PART
SUPPORT THIS REASONING.
TEMPERATURES NORTH OF THE BOUNDARY ARE HOLDING FAIRLY STEADY...OR
EASING DOWN EVER SO GRADUALLY. THE FREEZING RAIN ADVISORY AREA
LOOKS GOOD THOUGH AND MATCHES THE 32 DEGREE ISOTHERM AT THE
SURFACE AND REPORTS WE HAVE RECEIVED...SO NO CHANGES PLANNED
THERE. STILL A CHANCE SOME LIGHT FREEZING PRECIP INCHES ITS WAY
SOUTH OF THE ADVISORY LATE THIS MORNING OR AFTERNOON...INCLUDING
INTO NORTHERN COOK AND DUPAGE COUNTIES.
MTF
//PREV DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENETIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PRECIP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
MEDIUM AND LONG RANGE...MONDAY THROUGH THURSDAY...
MAIN CONCERNS BEYOND THIS WEEKEND ARE THE RETURN OF ARCTIC AIR AND
MUCH COLDER TEMPERATURES MONDAY-TUESDAY...AND THE POTENTIAL FOR A
LITTLE LIGHT SNOW CHRISTMAS EVE-CHRISTMAS DAY.
DEEP UPPER TROUGH TRAVERSING THE REGION MONDAY WITH FAIRLY
IMPRESSIVE SHORT WAVE ENERGY PASSING OVERHEAD. FORECAST SOUNDINGS
INDICATE SATURATION IN LOW LEVELS...WITH TEMPS NEAR -15C AS BOUNDARY
LAYER COOLS IN BLUSTERY COLD ADVECTION BEHIND DEPARTING WEEKEND LOW
PRESSURE SYSTEM. THIS SHOULD SUPPORT FLURRIES/LIGHT SNOW SHOWERS
ACROSS THE CWA INTO THE AFTERNOON HOURS. OF MORE IMPORTANCE THAN THE
POTENTIAL FOR LIGHT SNOW SHOWERS OR FLURRIES HOWEVER WILL BE THE
MUCH COLDER TEMPS AND WIND CHILLS AS ARCTIC AIR PLUNGES BACK INTO
THE REGION. TEMPS AT H8 FALL TO AROUND -16 C BY LATE AFTERNOON WITH
H9 TEMPS NEARLY SO...SUGGESTING SURFACE TEMPS MAY STRUGGLE TO RISE
ABOVE 10-15F AND WILL LIKELY FALL INTO THE SINGLE DIGITS ACROSS
NORTH CENTRAL IL AND WIND CHILLS IN THE NEGATIVE SINGLE DIGITS.
SURFACE HIGH PRESSURE RIDGE WILL BUILD ACROSS THE MISSISSIPPI VALLEY
AND INTO IL MONDAY NIGHT IN RESPONSE TO SUBSIDENCE BEHIND THE
DEPARTING UPPER TROUGH...WITH CLEARING SKIES...NEW SNOW COVER
ESPECIALLY FAR NORTHERN IL...AND DECREASING WINDS EXPECTED TO RESULT
IN STRONG RADIATIONAL COOLING. BOTH GFS AND ECMWF MOS DEPICT
SUB-ZERO LOWS ACROSS MUCH OF NORTHERN IL BY SUNRISE TUESDAY. SURFACE
HIGH PRESSURE RIDGE MOVES ACROSS THE AREA DURING THE DAY TUESDAY...
WITH WINDS BACKING TO THE SOUTH-SOUTHEAST DURING THE AFTERNOON AS
WARM ADVECTION DEVELOPS (ALOFT AT LEAST) IN ADVANCE OF A SHORT WAVE
EMERGING FROM THE PLAINS. MODERATION IN TEMPS LIMITED AT THE SURFACE
HOWEVER WITH VERY COLD START TO DAY AND STRONG INVERSION LIMITING
WARMING AT THE SURFACE WITH HIGHS IN THE TEENS/LOW 20S.
LONG RANGE GUIDANCE SIMILAR IN BRINGING SHORT WAVE TROUGH ACROSS
THE REGION DURING THE TUESDAY NIGHT/WEDNESDAY PERIOD AND ANOTHER
WEDNESDAY NIGHT/THURSDAY...THOUGH DIFFERENCES DO EXIST WITH
AMPLITUDE OF THESE INDIVIDUAL WAVES AND ASSOCIATED SURFACE
REFLECTIONS. THE ECMWF IS STRONGER/MORE AMPLIFIED WITH BOTH...
THOUGH AT THIS DISTANCE HAVE FOCUSED MAINLY ON SIMILARITIES BETWEEN
GUIDANCE. THIS YIELDS A LITTLE TEMPERATURE MODERATION CHRISTMAS EVE
AND CHRISTMAS DAY WITH A CHANCE OF SOME LIGHT SNOW...PERHAPS
0.5-1.0" BASED ON ROUGH QPF OUTPUT. LIGHT SNOW MAY LINGER ACROSS
THE EASTERN CWA CHRISTMAS NIGHT INTO THURSDAY WITH SURFACE COLD
FRONTAL TROUGH. AS MENTIONED...BRIEF MODERATION PRODUCES HIGHS IN
THE 20S/AROUND 30 FOR CHRISTMAS DAY THEN COLDER AIR LOOKS TO RETURN
THURSDAY BEHIND THE FRONT WITH TEMPS IN THE TEENS/LOW 20S.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* IFR CIG/VSBY TRENDS THIS AFTERNOON.
* WINDS GRADUALLY BACKING TO NORTH AND THEN NORTHWEST.
* PRECIPITATION TRENDS...MOST LIKELY LIQUID AT ORD/MDW BUT MIXED
PRECIP POSSIBLE.
LENNING
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE IS NOW MOVING NORTHEAST ACROSS CENTRAL MISSOURI WITH
A FRONTAL BOUNDARY STRETCHED FROM THE LOW TO SOUTHERN ONTARIO.
THIS FRONT HAS BEEN DRIFTING SOUTH THE LAST FEW HOURS WHICH HAS
HELPED VSBY TO NOTICEABLY IMPROVE WITH CIGS ALSO IMPROVING BUT AT
A MUCH SLOWER RATE. WAVES OF RAIN/DRIZZLE CONTINUE TO MOVE ACROSS
DPA/ORD/MDW/GYY WITH FREEZING RAIN AT RFD THANKS TO AN INFLUX OF
COLDER AIR. THIS COLDER AIR WILL SPREAD SOUTHWARD ACROSS THE OTHER
TERMINALS INTO THE AFTERNOON. WITH DAYTIME HEATING AND AN END TO
THE PRECIP ARRIVING THIS AFTERNOON THE THREAT FOR FZRA/FZDZ ACROSS
THE CHI/NW INDIANA TERMINALS LOOKS LOW. HOWEVER...IF COOLING
OCCURS MORE QUICKLY THAN FORECAST THEN THE THREAT FOR FREEZING
PRECIP WILL INCREASE EARLY THIS AFTERNOON. OTHERWISE...EXPECT IFR
CIG TO PREVAIL THROUGH MUCH OF THE DAY WITH MAINLY MVFR VSBY BY
MID MORNING IF NOT SOONER AT SITES THAT STILL HAVE IFR VSBY. WINDS
WILL VARY BETWEEN NORTH AND NORTH-NORTHEAST THROUGH THE AFTERNOON
THEN TURN NORTH-NORTHWEST THIS EVENING.
THE NEXT STORM SYSTEM WILL APPROACH FROM THE SOUTH SATURDAY...WITH
PRECIP POSSIBLY REACHING THE CHI/NW INDIANA TERMINALS DURING THE
MORNING. A MIX OF PRECIPITATION TYPES IS EXPECTED WITH DETAILS OF
TIMING OF TYPE CHANGES STILL UNCERTAIN. OVERALL...RFD WILL HAVE
THE BEST CHANCE FOR SIGNIFICANT ACCUMULATING SNOW...THOUGH SLEET
MAY MIX IN AT TIMES.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE IN IFR CIGS CONTINUING. LOW CONFIDENCE IN HOW
THEY CHANGE AFTER PRECIP ENDS THIS AFTERNOON.
* HIGH CONFIDENCE IN MVFR OR BETTER VSBY TODAY.
* HIGH CONFIDENCE IN WIND BACKING TO NORTHWEST...MEDIUM CONFIDENCE
ON TIMING.
* HIGH CONFIDENCE IN LIGHT RAIN/DRIZZLE CONTINUING THROUGH EARLY
AFTERNOON. LOW CONFIDENCE IN POTENTIAL FOR -FZRA/FZDZ THIS
AFTERNOON.
LENNING
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
301 AM CST
LOW PRESSURE CENTERED OVER NORTH-CENTRAL OKLAHOMA WILL TRACK
NORTHEAST ALONG A FRONTAL BOUNDARY WHICH EXTENDS NORTHEAST INTO
NORTHERN INDIANA AND EASTWARD ACROSS LAKE ERIE AND ONTARIO.
MEANWHILE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE LITTLE
THROUGH THE DAY. THE STRONGEST PRESSURE GRADIENT IS STARTING TO SET
UP EARLY THIS MORNING AND WILL LIKELY RESULT IN AN INCREASE IN
NORTHEAST WINDS ACROSS MUCH OF THE LAKE THROUGH MID MORNING BEFORE
THE PRESSURE GRADIENT EASES. SPEEDS MAY PUSH 30 KT FOR A TIME
THROUGH MID OR LATE MORNING...ESPECIALLY ACROSS CENTRAL SECTIONS OF
THE LAKE. THE LOW WILL PASS SOUTH OF THE LAKE LATER THIS AFTERNOON
AND BEGIN TO WEAKEN WITH THE HIGH WEAKENING AS WELL. ANOTHER SURFACE
LOW WILL DEVELOP OVER THE ARKLATEX SATURDAY AND LIFT NORTHEAST TO
NORTHERN OHIO BY SUNDAY AFTERNOON. A VERY STRONG HIGH WILL THEN
DEVELOP SOUTHWARD INTO THE NORTHERN PLAINS AS THE LOW MOVES INTO NEW
ENGLAND SUNDAY NIGHT. THIS WILL LEAVE LAKE MICHIGAN IN THE PRESSURE
GRADIENT BETWEEN THE TWO SYSTEMS SATURDAY NIGHT AND SUNDAY WITH
COLDER AIR SPILLING ACROSS THE LAKE AS WELL. THIS WILL SET THE STAGE
FOR ANOTHER ROUND OF STRONG WINDS WHICH WILL START OUT NORTHEAST
THEN SHIFT NORTH-NORTHWEST AND EASE UP LATE SUNDAY AFTERNOON. THE
HIGH WILL PASS SOUTH OF THE LAKE TUESDAY BEFORE LOW PRESSURE TRACKS
SOUTHEAST ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THIS
SHOULD LEAD TO ANOTHER PERIOD OF INCREASED WINDS...THIS TIME FROM
THE SOUTH AND SOUTHWEST WEDNESDAY. WILL KEEP SPEEDS BELOW GALE FORCE
THROUGH THE PERIOD BUT WILL NEED TO MONITOR FOR SHORT WINDOWS OF
GALE FORCE WINDS SATURDAY NIGHT AND SUNDAY MORNING...AND AGAIN EARLY
WEDNESDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 3 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 3 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 3
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 PM FRIDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
814 AM CST FRI DEC 20 2013
.DISCUSSION...
805 AM CST
HAVE EXPANDED THE DENSE FOG ADVISORY TO INCLUDE AREAS SOUTH OF A
PONTIAC TO VALPARAISO LINE. HAVE RECEIVED MULTIPLE REPORTS OF
DENSE FOG ALONG THE SYNOPTIC BOUNDARY...WHICH IS PRACTICALLY
STATIONARY AS THE 1006MB SFC LOW NEAR QUINCY EASES ITS WAY
NORTHEAST. GOOD POOLING OF MOISTURE AND LIGHT WINDS ALONG THIS
SHOULD CONTINUE TO ALLOW FOR DENSE FOG THROUGH 12P-3P...UNTIL THE
LOW LIFTS THROUGH THE AREA. THE RAP AND HRRR FOR THE MOST PART
SUPPORT THIS REASONING.
TEMPERATURES NORTH OF THE BOUNDARY ARE HOLDING FAIRLY STEADY...OR
EASING DOWN EVER SO GRADUALLY. THE FREEZING RAIN ADVISORY AREA
LOOKS GOOD THOUGH AND MATCHES THE 32 DEGREE ISOTHERM AT THE
SURFACE AND REPORTS WE HAVE RECEIVED...SO NO CHANGES PLANNED
THERE. STILL A CHANCE SOME LIGHT FREEZING PRECIP INCHES ITS WAY
SOUTH OF THE ADVISORY LATE THIS MORNING OR AFTERNOON...INCLUDING
INTO NORTHERN COOK AND DUPAGE COUNTIES.
MTF
&&
.PREV DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENETIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PRECIP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
MEDIUM AND LONG RANGE...MONDAY THROUGH THURSDAY...
MAIN CONCERNS BEYOND THIS WEEKEND ARE THE RETURN OF ARCTIC AIR AND
MUCH COLDER TEMPERATURES MONDAY-TUESDAY...AND THE POTENTIAL FOR A
LITTLE LIGHT SNOW CHRISTMAS EVE-CHRISTMAS DAY.
DEEP UPPER TROUGH TRAVERSING THE REGION MONDAY WITH FAIRLY
IMPRESSIVE SHORT WAVE ENERGY PASSING OVERHEAD. FORECAST SOUNDINGS
INDICATE SATURATION IN LOW LEVELS...WITH TEMPS NEAR -15C AS BOUNDARY
LAYER COOLS IN BLUSTERY COLD ADVECTION BEHIND DEPARTING WEEKEND LOW
PRESSURE SYSTEM. THIS SHOULD SUPPORT FLURRIES/LIGHT SNOW SHOWERS
ACROSS THE CWA INTO THE AFTERNOON HOURS. OF MORE IMPORTANCE THAN THE
POTENTIAL FOR LIGHT SNOW SHOWERS OR FLURRIES HOWEVER WILL BE THE
MUCH COLDER TEMPS AND WIND CHILLS AS ARCTIC AIR PLUNGES BACK INTO
THE REGION. TEMPS AT H8 FALL TO AROUND -16 C BY LATE AFTERNOON WITH
H9 TEMPS NEARLY SO...SUGGESTING SURFACE TEMPS MAY STRUGGLE TO RISE
ABOVE 10-15F AND WILL LIKELY FALL INTO THE SINGLE DIGITS ACROSS
NORTH CENTRAL IL AND WIND CHILLS IN THE NEGATIVE SINGLE DIGITS.
SURFACE HIGH PRESSURE RIDGE WILL BUILD ACROSS THE MISSISSIPPI VALLEY
AND INTO IL MONDAY NIGHT IN RESPONSE TO SUBSIDENCE BEHIND THE
DEPARTING UPPER TROUGH...WITH CLEARING SKIES...NEW SNOW COVER
ESPECIALLY FAR NORTHERN IL...AND DECREASING WINDS EXPECTED TO RESULT
IN STRONG RADIATIONAL COOLING. BOTH GFS AND ECMWF MOS DEPICT
SUB-ZERO LOWS ACROSS MUCH OF NORTHERN IL BY SUNRISE TUESDAY. SURFACE
HIGH PRESSURE RIDGE MOVES ACROSS THE AREA DURING THE DAY TUESDAY...
WITH WINDS BACKING TO THE SOUTH-SOUTHEAST DURING THE AFTERNOON AS
WARM ADVECTION DEVELOPS (ALOFT AT LEAST) IN ADVANCE OF A SHORT WAVE
EMERGING FROM THE PLAINS. MODERATION IN TEMPS LIMITED AT THE SURFACE
HOWEVER WITH VERY COLD START TO DAY AND STRONG INVERSION LIMITING
WARMING AT THE SURFACE WITH HIGHS IN THE TEENS/LOW 20S.
LONG RANGE GUIDANCE SIMILAR IN BRINGING SHORT WAVE TROUGH ACROSS
THE REGION DURING THE TUESDAY NIGHT/WEDNESDAY PERIOD AND ANOTHER
WEDNESDAY NIGHT/THURSDAY...THOUGH DIFFERENCES DO EXIST WITH
AMPLITUDE OF THESE INDIVIDUAL WAVES AND ASSOCIATED SURFACE
REFLECTIONS. THE ECMWF IS STRONGER/MORE AMPLIFIED WITH BOTH...
THOUGH AT THIS DISTANCE HAVE FOCUSED MAINLY ON SIMILARITIES BETWEEN
GUIDANCE. THIS YIELDS A LITTLE TEMPERATURE MODERATION CHRISTMAS EVE
AND CHRISTMAS DAY WITH A CHANCE OF SOME LIGHT SNOW...PERHAPS
0.5-1.0" BASED ON ROUGH QPF OUTPUT. LIGHT SNOW MAY LINGER ACROSS
THE EASTERN CWA CHRISTMAS NIGHT INTO THURSDAY WITH SURFACE COLD
FRONTAL TROUGH. AS MENTIONED...BRIEF MODERATION PRODUCES HIGHS IN
THE 20S/AROUND 30 FOR CHRISTMAS DAY THEN COLDER AIR LOOKS TO RETURN
THURSDAY BEHIND THE FRONT WITH TEMPS IN THE TEENS/LOW 20S.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* IFR CIGS LIKELY CONTINUING THROUGH THE AFTERNOON AND POSSIBLY
INTO TONIGHT.
* VSBY GRADUALLY THIS MORNING BUT LIKELY LEVELS OFF AT MVFR
THROUGH THE AFTERNOON.
* VARIABLE NORTH TO NORTH-NORTHEAST WINDS WITH SPEEDS 10-12 KT
WITH A FEW GUSTS INTO THE UPPER TEENS POSSIBLE. WINDS TURN NORTH
THEN NORTH-NORTHWEST THIS EVENING.
* PERIODIC LIGHT RAIN AND DRIZZLE CONTINUE THROUGH EARLY
AFTERNOON. TEMPS WILL FALL SO SLIGHT CHANCE FOR -FZRA/FZDZ THIS
AFTERNOON BEFORE PRECIP ENDS.
MDB/MTF
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE IS NOW MOVING NORTHEAST ACROSS CENTRAL MISSOURI WITH
A FRONTAL BOUNDARY STRETCHED FROM THE LOW TO SOUTHERN ONTARIO.
THIS FRONT HAS BEEN DRIFTING SOUTH THE LAST FEW HOURS WHICH HAS
HELPED VSBY TO NOTICEABLY IMPROVE WITH CIGS ALSO IMPROVING BUT AT
A MUCH SLOWER RATE. WAVES OF RAIN/DRIZZLE CONTINUE TO MOVE ACROSS
DPA/ORD/MDW/GYY WITH FREEZING RAIN AT RFD THANKS TO AN INFLUX OF
COLDER AIR. THIS COLDER AIR WILL SPREAD SOUTHWARD ACROSS THE OTHER
TERMINALS INTO THE AFTERNOON. WITH DAYTIME HEATING AND AN END TO
THE PRECIP ARRIVING THIS AFTERNOON THE THREAT FOR FZRA/FZDZ ACROSS
THE CHI/NW INDIANA TERMINALS LOOKS LOW. HOWEVER...IF COOLING
OCCURS MORE QUICKLY THAN FORECAST THEN THE THREAT FOR FREEZING
PRECIP WILL INCREASE EARLY THIS AFTERNOON. OTHERWISE...EXPECT IFR
CIG TO PREVAIL THROUGH MUCH OF THE DAY WITH MAINLY MVFR VSBY BY
MID MORNING IF NOT SOONER AT SITES THAT STILL HAVE IFR VSBY. WINDS
WILL VARY BETWEEN NORTH AND NORTH-NORTHEAST THROUGH THE AFTERNOON
THEN TURN NORTH-NORTHWEST THIS EVENING.
THE NEXT STORM SYSTEM WILL APPROACH FROM THE SOUTH SATURDAY...WITH
PRECIP POSSIBLY REACHING THE CHI/NW INDIANA TERMINALS DURING THE
MORNING. A MIX OF PRECIPITATION TYPES IS EXPECTED WITH DETAILS OF
TIMING OF TYPE CHANGES STILL UNCERTAIN. OVERALL...RFD WILL HAVE
THE BEST CHANCE FOR SIGNIFICANT ACCUMULATING SNOW...THOUGH SLEET
MAY MIX IN AT TIMES.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* HIGH CONFIDENCE IN IFR CIGS CONTINUING THROUGH MUCH OF THE DAY.
LOW CONFIDENCE IN HOW QUICKLY CIGS IMPROVE.
* HIGH CONFIDENCE IN MAINLY MVFR VSBY TODAY.
* HIGH CONFIDENCE IN WIND TRENDS.
* HIGH CONFIDENCE IN LIGHT RAIN/DRIZZLE CONTINUING THROUGH EARLY
AFTERNOON. LOW CONFIDENCE IN POTENTIAL FOR -FZRA/FZDZ THIS
AFTERNOON.
MDB/MTF
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
301 AM CST
LOW PRESSURE CENTERED OVER NORTH-CENTRAL OKLAHOMA WILL TRACK
NORTHEAST ALONG A FRONTAL BOUNDARY WHICH EXTENDS NORTHEAST INTO
NORTHERN INDIANA AND EASTWARD ACROSS LAKE ERIE AND ONTARIO.
MEANWHILE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE LITTLE
THROUGH THE DAY. THE STRONGEST PRESSURE GRADIENT IS STARTING TO SET
UP EARLY THIS MORNING AND WILL LIKELY RESULT IN AN INCREASE IN
NORTHEAST WINDS ACROSS MUCH OF THE LAKE THROUGH MID MORNING BEFORE
THE PRESSURE GRADIENT EASES. SPEEDS MAY PUSH 30 KT FOR A TIME
THROUGH MID OR LATE MORNING...ESPECIALLY ACROSS CENTRAL SECTIONS OF
THE LAKE. THE LOW WILL PASS SOUTH OF THE LAKE LATER THIS AFTERNOON
AND BEGIN TO WEAKEN WITH THE HIGH WEAKENING AS WELL. ANOTHER SURFACE
LOW WILL DEVELOP OVER THE ARKLATEX SATURDAY AND LIFT NORTHEAST TO
NORTHERN OHIO BY SUNDAY AFTERNOON. A VERY STRONG HIGH WILL THEN
DEVELOP SOUTHWARD INTO THE NORTHERN PLAINS AS THE LOW MOVES INTO NEW
ENGLAND SUNDAY NIGHT. THIS WILL LEAVE LAKE MICHIGAN IN THE PRESSURE
GRADIENT BETWEEN THE TWO SYSTEMS SATURDAY NIGHT AND SUNDAY WITH
COLDER AIR SPILLING ACROSS THE LAKE AS WELL. THIS WILL SET THE STAGE
FOR ANOTHER ROUND OF STRONG WINDS WHICH WILL START OUT NORTHEAST
THEN SHIFT NORTH-NORTHWEST AND EASE UP LATE SUNDAY AFTERNOON. THE
HIGH WILL PASS SOUTH OF THE LAKE TUESDAY BEFORE LOW PRESSURE TRACKS
SOUTHEAST ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THIS
SHOULD LEAD TO ANOTHER PERIOD OF INCREASED WINDS...THIS TIME FROM
THE SOUTH AND SOUTHWEST WEDNESDAY. WILL KEEP SPEEDS BELOW GALE FORCE
THROUGH THE PERIOD BUT WILL NEED TO MONITOR FOR SHORT WINDOWS OF
GALE FORCE WINDS SATURDAY NIGHT AND SUNDAY MORNING...AND AGAIN EARLY
WEDNESDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 3 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
DENSE FOG ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039 UNTIL 3 PM
FRIDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 3
PM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...NEARSHORE WINTHROP TO WILMETTE HARBORS UNTIL 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 3 PM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
559 AM CST FRI DEC 20 2013
.DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENTIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PREICP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
MEDIUM AND LONG RANGE...MONDAY THROUGH THURSDAY...
MAIN CONCERNS BEYOND THIS WEEKEND ARE THE RETURN OF ARCTIC AIR AND
MUCH COLDER TEMPERATURES MONDAY-TUESDAY...AND THE POTENTIAL FOR A
LITTLE LIGHT SNOW CHRISTMAS EVE-CHRISTMAS DAY.
DEEP UPPER TROUGH TRAVERSING THE REGION MONDAY WITH FAIRLY
IMPRESSIVE SHORT WAVE ENERGY PASSING OVERHEAD. FORECAST SOUNDINGS
INDICATE SATURATION IN LOW LEVELS...WITH TEMPS NEAR -15C AS BOUNDARY
LAYER COOLS IN BLUSTERY COLD ADVECTION BEHIND DEPARTING WEEKEND LOW
PRESSURE SYSTEM. THIS SHOULD SUPPORT FLURRIES/LIGHT SNOW SHOWERS
ACROSS THE CWA INTO THE AFTERNOON HOURS. OF MORE IMPORTANCE THAN THE
POTENTIAL FOR LIGHT SNOW SHOWERS OR FLURRIES HOWEVER WILL BE THE
MUCH COLDER TEMPS AND WIND CHILLS AS ARCTIC AIR PLUNGES BACK INTO
THE REGION. TEMPS AT H8 FALL TO AROUND -16 C BY LATE AFTERNOON WITH
H9 TEMPS NEARLY SO...SUGGESTING SURFACE TEMPS MAY STRUGGLE TO RISE
ABOVE 10-15F AND WILL LIKELY FALL INTO THE SINGLE DIGITS ACROSS
NORTH CENTRAL IL AND WIND CHILLS IN THE NEGATIVE SINGLE DIGITS.
SURFACE HIGH PRESSURE RIDGE WILL BUILD ACROSS THE MISSISSIPPI VALLEY
AND INTO IL MONDAY NIGHT IN RESPONSE TO SUBSIDENCE BEHIND THE
DEPARTING UPPER TROUGH...WITH CLEARING SKIES...NEW SNOW COVER
ESPECIALLY FAR NORTHERN IL...AND DECREASING WINDS EXPECTED TO RESULT
IN STRONG RADIATIONAL COOLING. BOTH GFS AND ECMWF MOS DEPICT
SUB-ZERO LOWS ACROSS MUCH OF NORTHERN IL BY SUNRISE TUESDAY. SURFACE
HIGH PRESSURE RIDGE MOVES ACROSS THE AREA DURING THE DAY TUESDAY...
WITH WINDS BACKING TO THE SOUTH-SOUTHEAST DURING THE AFTERNOON AS
WARM ADVECTION DEVELOPS (ALOFT AT LEAST) IN ADVANCE OF A SHORT WAVE
EMERGING FROM THE PLAINS. MODERATION IN TEMPS LIMITED AT THE SURFACE
HOWEVER WITH VERY COLD START TO DAY AND STRONG INVERSION LIMITING
WARMING AT THE SURFACE WITH HIGHS IN THE TEENS/LOW 20S.
LONG RANGE GUIDANCE SIMILAR IN BRINGING SHORT WAVE TROUGH ACROSS
THE REGION DURING THE TUESDAY NIGHT/WEDNESDAY PERIOD AND ANOTHER
WEDNESDAY NIGHT/THURSDAY...THOUGH DIFFERENCES DO EXIST WITH
AMPLITUDE OF THESE INDIVIDUAL WAVES AND ASSOCIATED SURFACE
REFLECTIONS. THE ECMWF IS STRONGER/MORE AMPLIFIED WITH BOTH...
THOUGH AT THIS DISTANCE HAVE FOCUSED MAINLY ON SIMILARITIES BETWEEN
GUIDANCE. THIS YIELDS A LITTLE TEMPERATURE MODERATION CHRISTMAS EVE
AND CHRISTMAS DAY WITH A CHANCE OF SOME LIGHT SNOW...PERHAPS
0.5-1.0" BASED ON ROUGH QPF OUTPUT. LIGHT SNOW MAY LINGER ACROSS
THE EASTERN CWA CHRISTMAS NIGHT INTO THURSDAY WITH SURFACE COLD
FRONTAL TROUGH. AS MENTIONED...BRIEF MODERATION PRODUCES HIGHS IN
THE 20S/AROUND 30 FOR CHRISTMAS DAY THEN COLDER AIR LOOKS TO RETURN
THURSDAY BEHIND THE FRONT WITH TEMPS IN THE TEENS/LOW 20S.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* IFR CIGS LIKELY CONTINUING THROUGH THE AFTERNOON AND POSSIBLY
INTO TONIGHT.
* VSBY GRADUALLY THIS MORNING BUT LIKELY LEVELS OFF AT MVFR
THROUGH THE AFTERNOON.
* VARIABLE NORTH TO NORTH-NORTHEAST WINDS WITH SPEEDS 10-12 KT
WITH A FEW GUSTS INTO THE UPPER TEENS POSSIBLE. WINDS TURN NORTH
THEN NORTH-NORTHWEST THIS EVENING.
* PERIODIC LIGHT RAIN AND DRIZZLE CONTINUE THROUGH EARLY
AFTERNOON. TEMPS WILL FALL SO SLIGHT CHANCE FOR -FZRA/FZDZ THIS
AFTERNOON BEFORE PRECIP ENDS.
MDB
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE IS NOW MOVING NORTHEAST ACROSS CENTRAL MISSOURI WITH
A FRONTAL BOUNDARY STRETCHED FROM THE LOW TO SOUTHERN ONTARIO.
THIS FRONT HAS BEEN DRIFTING SOUTH THE LAST FEW HOURS WHICH HAS
HELPED VSBY TO NOTICEABLY IMPROVE WITH CIGS ALSO IMPROVING BUT AT
A MUCH SLOWER RATE. WAVES OF RAIN/DRIZZLE CONTINUE TO MOVE ACROSS
DPA/ORD/MDW/GYY WITH FREEZING RAIN AT RFD THANKS TO AN INFLUX OF
COLDER AIR. THIS COLDER AIR WILL SPREAD SOUTHWARD ACROSS THE OTHER
TERMINALS INTO THE AFTERNOON. WITH DAYTIME HEATING AND AN END TO
THE PRECIP ARRIVING THIS AFTERNOON THE THREAT FOR FZRA/FZDZ ACROSS
THE CHI/NW INDIANA TERMINALS LOOKS LOW. HOWEVER...IF COOLING
OCCURS MORE QUICKLY THAN FORECAST THEN THE THREAT FOR FREEZING
PRECIP WILL INCREASE EARLY THIS AFTERNOON. OTHERWISE...EXPECT IFR
CIG TO PREVAIL THROUGH MUCH OF THE DAY WITH MAINLY MVFR VSBY BY
MID MORNING IF NOT SOONER AT SITES THAT STILL HAVE IFR VSBY. WINDS
WILL VARY BETWEEN NORTH AND NORTH-NORTHEAST THROUGH THE AFTERNOON
THEN TURN NORTH-NORTHWEST THIS EVENING.
THE NEXT STORM SYSTEM WILL APPROACH FROM THE SOUTH SATURDAY...WITH
PRECIP POSSIBLY REACHING THE CHI/NW INDIANA TERMINALS DURING THE
MORNING. A MIX OF PRECIPITATION TYPES IS EXPECTED WITH DETAILS OF
TIMING OF TYPE CHANGES STILL UNCERTAIN. OVERALL...RFD WILL HAVE
THE BEST CHANCE FOR SIGNIFICANT ACCUMULATING SNOW...THOUGH SLEET
MAY MIX IN AT TIMES.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* HIGH CONFIDENCE IN IFR CIGS CONTINUING THROUGH MUCH OF THE DAY.
LOW CONFIDENCE IN HOW QUICKLY CIGS IMPROVE.
* HIGH CONFIDENCE IN MAINLY MVFR VSBY TODAY.
* HIGH CONFIDENCE IN WIND TRENDS.
* HIGH CONFIDENCE IN LIGHT RAIN/DRIZZLE CONTINUING THROUGH EARLY
AFTERNOON. LOW CONFIDENCE IN POTENTIAL FOR -FZRA/FZDZ THIS
AFTERNOON.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z SUNDAY-12Z FRIDAY...UPDATED 12Z...
SATURDAY NIGHT...WINTRY MIX...IFR LIKELY.
SUNDAY...SNOW AND IFR.
MONDAY...CHANCE FOR SNOW...MVFR/IFR POSSIBLE.
TUESDAY...VFR.
WEDNESDAY...SLIGHT CHANCE SNOW...MVFR POSSIBLE.
THURSDAY...MVFR BECOMING VFR.
MDB
&&
.MARINE...
301 AM CST
LOW PRESSURE CENTERED OVER NORTH-CENTRAL OKLAHOMA WILL TRACK
NORTHEAST ALONG A FRONTAL BOUNDARY WHICH EXTENDS NORTHEAST INTO
NORTHERN INDIANA AND EASTWARD ACROSS LAKE ERIE AND ONTARIO.
MEANWHILE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE LITTLE
THROUGH THE DAY. THE STRONGEST PRESSURE GRADIENT IS STARTING TO SET
UP EARLY THIS MORNING AND WILL LIKELY RESULT IN AN INCREASE IN
NORTHEAST WINDS ACROSS MUCH OF THE LAKE THROUGH MID MORNING BEFORE
THE PRESSURE GRADIENT EASES. SPEEDS MAY PUSH 30 KT FOR A TIME
THROUGH MID OR LATE MORNING...ESPECIALLY ACROSS CENTRAL SECTIONS OF
THE LAKE. THE LOW WILL PASS SOUTH OF THE LAKE LATER THIS AFTERNOON
AND BEGIN TO WEAKEN WITH THE HIGH WEAKENING AS WELL. ANOTHER SURFACE
LOW WILL DEVELOP OVER THE ARKLATEX SATURDAY AND LIFT NORTHEAST TO
NORTHERN OHIO BY SUNDAY AFTERNOON. A VERY STRONG HIGH WILL THEN
DEVELOP SOUTHWARD INTO THE NORTHERN PLAINS AS THE LOW MOVES INTO NEW
ENGLAND SUNDAY NIGHT. THIS WILL LEAVE LAKE MICHIGAN IN THE PRESSURE
GRADIENT BETWEEN THE TWO SYSTEMS SATURDAY NIGHT AND SUNDAY WITH
COLDER AIR SPILLING ACROSS THE LAKE AS WELL. THIS WILL SET THE STAGE
FOR ANOTHER ROUND OF STRONG WINDS WHICH WILL START OUT NORTHEAST
THEN SHIFT NORTH-NORTHWEST AND EASE UP LATE SUNDAY AFTERNOON. THE
HIGH WILL PASS SOUTH OF THE LAKE TUESDAY BEFORE LOW PRESSURE TRACKS
SOUTHEAST ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THIS
SHOULD LEAD TO ANOTHER PERIOD OF INCREASED WINDS...THIS TIME FROM
THE SOUTH AND SOUTHWEST WEDNESDAY. WILL KEEP SPEEDS BELOW GALE FORCE
THROUGH THE PERIOD BUT WILL NEED TO MONITOR FOR SHORT WINDOWS OF
GALE FORCE WINDS SATURDAY NIGHT AND SUNDAY MORNING...AND AGAIN EARLY
WEDNESDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 3 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740...9 AM FRIDAY TO 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 AM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
510 AM CST FRI DEC 20 2013
.DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENTIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PREICP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
MEDIUM AND LONG RANGE...MONDAY THROUGH THURSDAY...
MAIN CONCERNS BEYOND THIS WEEKEND ARE THE RETURN OF ARCTIC AIR AND
MUCH COLDER TEMPERATURES MONDAY-TUESDAY...AND THE POTENTIAL FOR A
LITTLE LIGHT SNOW CHRISTMAS EVE-CHRISTMAS DAY.
DEEP UPPER TROUGH TRAVERSING THE REGION MONDAY WITH FAIRLY
IMPRESSIVE SHORT WAVE ENERGY PASSING OVERHEAD. FORECAST SOUNDINGS
INDICATE SATURATION IN LOW LEVELS...WITH TEMPS NEAR -15C AS BOUNDARY
LAYER COOLS IN BLUSTERY COLD ADVECTION BEHIND DEPARTING WEEKEND LOW
PRESSURE SYSTEM. THIS SHOULD SUPPORT FLURRIES/LIGHT SNOW SHOWERS
ACROSS THE CWA INTO THE AFTERNOON HOURS. OF MORE IMPORTANCE THAN THE
POTENTIAL FOR LIGHT SNOW SHOWERS OR FLURRIES HOWEVER WILL BE THE
MUCH COLDER TEMPS AND WIND CHILLS AS ARCTIC AIR PLUNGES BACK INTO
THE REGION. TEMPS AT H8 FALL TO AROUND -16 C BY LATE AFTERNOON WITH
H9 TEMPS NEARLY SO...SUGGESTING SURFACE TEMPS MAY STRUGGLE TO RISE
ABOVE 10-15F AND WILL LIKELY FALL INTO THE SINGLE DIGITS ACROSS
NORTH CENTRAL IL AND WIND CHILLS IN THE NEGATIVE SINGLE DIGITS.
SURFACE HIGH PRESSURE RIDGE WILL BUILD ACROSS THE MISSISSIPPI VALLEY
AND INTO IL MONDAY NIGHT IN RESPONSE TO SUBSIDENCE BEHIND THE
DEPARTING UPPER TROUGH...WITH CLEARING SKIES...NEW SNOW COVER
ESPECIALLY FAR NORTHERN IL...AND DECREASING WINDS EXPECTED TO RESULT
IN STRONG RADIATIONAL COOLING. BOTH GFS AND ECMWF MOS DEPICT
SUB-ZERO LOWS ACROSS MUCH OF NORTHERN IL BY SUNRISE TUESDAY. SURFACE
HIGH PRESSURE RIDGE MOVES ACROSS THE AREA DURING THE DAY TUESDAY...
WITH WINDS BACKING TO THE SOUTH-SOUTHEAST DURING THE AFTERNOON AS
WARM ADVECTION DEVELOPS (ALOFT AT LEAST) IN ADVANCE OF A SHORT WAVE
EMERGING FROM THE PLAINS. MODERATION IN TEMPS LIMITED AT THE SURFACE
HOWEVER WITH VERY COLD START TO DAY AND STRONG INVERSION LIMITING
WARMING AT THE SURFACE WITH HIGHS IN THE TEENS/LOW 20S.
LONG RANGE GUIDANCE SIMILAR IN BRINGING SHORT WAVE TROUGH ACROSS
THE REGION DURING THE TUESDAY NIGHT/WEDNESDAY PERIOD AND ANOTHER
WEDNESDAY NIGHT/THURSDAY...THOUGH DIFFERENCES DO EXIST WITH
AMPLITUDE OF THESE INDIVIDUAL WAVES AND ASSOCIATED SURFACE
REFLECTIONS. THE ECMWF IS STRONGER/MORE AMPLIFIED WITH BOTH...
THOUGH AT THIS DISTANCE HAVE FOCUSED MAINLY ON SIMILARITIES BETWEEN
GUIDANCE. THIS YIELDS A LITTLE TEMPERATURE MODERATION CHRISTMAS EVE
AND CHRISTMAS DAY WITH A CHANCE OF SOME LIGHT SNOW...PERHAPS
0.5-1.0" BASED ON ROUGH QPF OUTPUT. LIGHT SNOW MAY LINGER ACROSS
THE EASTERN CWA CHRISTMAS NIGHT INTO THURSDAY WITH SURFACE COLD
FRONTAL TROUGH. AS MENTIONED...BRIEF MODERATION PRODUCES HIGHS IN
THE 20S/AROUND 30 FOR CHRISTMAS DAY THEN COLDER AIR LOOKS TO RETURN
THURSDAY BEHIND THE FRONT WITH TEMPS IN THE TEENS/LOW 20S.
RATZER
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* CIG/VSBY TRENDS THROUGH THE DAY WITH IFR CONTINUING. DENSE FOG
IN CLOSE PROXIMITY TO MDW WITH 1/4-1/2SM VSBY STILL POSSIBLE
THROUGH DAYBREAK.
* PERIODIC -RA/DZ THROUGH MIDDAY WITH LOW CHANCE FOR SOME
-FZRA/FZDZ THIS AFTERNOON...MAINLY A ORD.
* NORTH TO NORTH-NORTHEAST WINDS INCREASING TO AROUND 10 KT THEN
TURNING NORTHWEST THIS EVENING.
MDB
//DISCUSSION...UPDATED 09Z...
WARM FRONTAL BOUNDARY HAS BEEN OSCILLATING NORTH AND SOUTH OVER A
NARROW CORRIDOR FROM ROUGHLY KGBG TO KGYY AND SOUTHERN LOWER
MICHIGAN THE PAST FEW HOURS. THIS HAS RESULTED IN A SOMEWHAT
TRANSIENT BAND OF DENSE FOG WHICH AS BEEN AFFECTING MDW AND GYY AT
TIMES. A LOOK AT AREA WEBCAMS AND SURFACE OBS SHOWS THAT THERE HAS
BEEN SOME SLIGHT IMPROVEMENT IN VSBY RIGHT ALONG THE BOUNDARY BUT
THIS MAY BE DUE TO THE BAND OF DENSE FOG MOVING BACK AND FORTH VS.
ANY CHANGE IN LOWEST VSBYS. EXPECT THAT THE BOUNDARY WILL MEANDER
THROUGH DAYBREAK LEAVING MDW/GYY IN A VARIABLE VSBY SITUATION AND
CANNOT RULE OUT A RETURN TO 1/4-1/2SM VSBY FOR AT LEAST A SHORT
TIME. THE BOUNDARY DOES LOOK TO PUSH SOUTH LATER THIS MORNING AS
SURFACE LOW PRESSURE MOVES NORTHEAST ALONG IT. THIS SHOULD ALLOW
NORTHERLY WINDS TO SET UP WITH COOLER AIR SPREADING SOUTH WHICH
SHOULD HELP VSBY. MAY BE TOUGH TO LOSE THE IFR CIGS BUT MVFR VSBY
LOOKS TO OCCUR TOWARD/DURING THE AFTERNOON AT SOME POINT.
OTHERWISE PERIODS OF -RA/DZ WILL CONTINUE THROUGH THE MORNING.
MDB
FROM 06Z...
MESSY CONDITIONS CONTINUE ACROSS THE TERMINALS TONIGHT WITH A
FRONTAL BOUNDARY STRETCHING FROM LOW PRESSURE OVER OKLAHOMA TO
ROUGHLY A KEOK TO KC75 TO KVPZ LINE. ABUNDANT MOISTURE AND LIFT
CONTINUE OVER THE BOUNDARY BRINGING RAIN SHOWERS AND AREAS OF
DRIZZLE TO THE TERMINALS. VSBY IS LOWEST RIGHT ALONG THE BOUNDARY
WITH GYY AROUND 1/4SM AND THIS WILL LIKELY PERSIST AS LONG AS THE
BOUNDARY IS NEARBY...WHICH AT THIS POINT LOOKS TO BE FOR MUCH OF
THE OVERNIGHT. AREAS NORTH HAVE SEEN VSBY GENERALLY AROUND A MILE
AND THIS SHOULD BE THE TREND THROUGH THE NIGHT...THOUGH THERE MAY
BE SOME DOWNWARD FLUCTUATIONS AT TIMES. CIGS SHOULD STAY STEADY
IN THE 002-004 RANGE THROUGH THE NIGHT AS WELL. RFD MAY SEE SOME
FREEZING RAIN/FREEZING DRIZZLE OVERNIGHT AS TEMPS COOL SLIGHTLY.
THINGS BECOME LESS CERTAIN AFTER DAYBREAK. THE LOW WILL TRACK
NORTHEAST TO NORTH-CENTRAL INDIANA BY FRIDAY AFTERNOON TURNING
WINDS FROM NORTHEAST TO NORTH-NORTHWEST THROUGH THE AFTERNOON. THE
MAIN QUESTION WILL BE HOW QUICKLY AND TO WHAT EXTENT CIGS/VSBY
IMPROVE. WITH THE BOUNDARY STILL IN THE AREA THROUGH THE MORNING
WILL ONLY HAVE VERY MINOR INCREASES IN CIGS/VSBY WITH BETTER
INCREASES DURING THE AFTERNOON AS COLDER AIR FILTERS INTO THE
REGION. SHOWERS/DRIZZLE WILL CONTINUE PERIODICALLY BEFORE TAPERING
OFF DURING THE AFTERNOON. RFD WILL HAVE THE BEST CHANCE OF SEEING
FREEZING RAIN THROUGH THE MORNING...WITH A LOW CHANCE THAT SOME
LIGHT FREEZING RAIN OR FREEZING DRIZZLE WILL MAKE IT INTO THE
CHICAGO TERMINALS DURING THE EARLY AFTERNOON AS COLDER AIR
ARRIVES. MVFR AND POSSIBLY IFR LOOK TO BE IN PLACE FOR FRIDAY
EVENING WITH NORTH-NORTHWEST WINDS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN IFR CONTINUING WITH LOWEST CONDITIONS THROUGH
DAYBREAK. LOW CONFIDENCE WITH SPEED/MAGNITUDE OF CIG/VSBY
IMPROVEMENT THROUGH THE DAY.
* HIGH CONFIDENCE IN PRECIP WINDING DOWN THIS AFTERNOON...MEDIUM-
HIGH CONFIDENCE THAT THREAT FOR -FZRA/FZDZ AT ORD IS LOW.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SAT...WINTRY MIX OF PRECIP FROM MIDDAY ON...WITH A CHANCE OF A
PERIOD OF FREEZING RAIN DURING THE NIGHT. MVFR TO IFR.
SUN...SNOW. MVFR TO IFR.
MON...MVFR CIGS. CHANCE OF SNOW SHOWERS WITH IFR.
TUE...VFR.
WED...VFR BECOMING MVFR CIGS.
THU...MVFR CIGS IMPROVING TO VFR.
TRS
&&
.MARINE...
301 AM CST
LOW PRESSURE CENTERED OVER NORTH-CENTRAL OKLAHOMA WILL TRACK
NORTHEAST ALONG A FRONTAL BOUNDARY WHICH EXTENDS NORTHEAST INTO
NORTHERN INDIANA AND EASTWARD ACROSS LAKE ERIE AND ONTARIO.
MEANWHILE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE LITTLE
THROUGH THE DAY. THE STRONGEST PRESSURE GRADIENT IS STARTING TO SET
UP EARLY THIS MORNING AND WILL LIKELY RESULT IN AN INCREASE IN
NORTHEAST WINDS ACROSS MUCH OF THE LAKE THROUGH MID MORNING BEFORE
THE PRESSURE GRADIENT EASES. SPEEDS MAY PUSH 30 KT FOR A TIME
THROUGH MID OR LATE MORNING...ESPECIALLY ACROSS CENTRAL SECTIONS OF
THE LAKE. THE LOW WILL PASS SOUTH OF THE LAKE LATER THIS AFTERNOON
AND BEGIN TO WEAKEN WITH THE HIGH WEAKENING AS WELL. ANOTHER SURFACE
LOW WILL DEVELOP OVER THE ARKLATEX SATURDAY AND LIFT NORTHEAST TO
NORTHERN OHIO BY SUNDAY AFTERNOON. A VERY STRONG HIGH WILL THEN
DEVELOP SOUTHWARD INTO THE NORTHERN PLAINS AS THE LOW MOVES INTO NEW
ENGLAND SUNDAY NIGHT. THIS WILL LEAVE LAKE MICHIGAN IN THE PRESSURE
GRADIENT BETWEEN THE TWO SYSTEMS SATURDAY NIGHT AND SUNDAY WITH
COLDER AIR SPILLING ACROSS THE LAKE AS WELL. THIS WILL SET THE STAGE
FOR ANOTHER ROUND OF STRONG WINDS WHICH WILL START OUT NORTHEAST
THEN SHIFT NORTH-NORTHWEST AND EASE UP LATE SUNDAY AFTERNOON. THE
HIGH WILL PASS SOUTH OF THE LAKE TUESDAY BEFORE LOW PRESSURE TRACKS
SOUTHEAST ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THIS
SHOULD LEAD TO ANOTHER PERIOD OF INCREASED WINDS...THIS TIME FROM
THE SOUTH AND SOUTHWEST WEDNESDAY. WILL KEEP SPEEDS BELOW GALE FORCE
THROUGH THE PERIOD BUT WILL NEED TO MONITOR FOR SHORT WINDOWS OF
GALE FORCE WINDS SATURDAY NIGHT AND SUNDAY MORNING...AND AGAIN EARLY
WEDNESDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011-ILZ012 UNTIL 3 PM FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740...9 AM FRIDAY TO 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 AM FRIDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
356 AM CST FRI DEC 20 2013
.DISCUSSION...
355 AM CST
SEVERAL ISSUES ONGOING THIS MORNING AS WELL THROUGH THE
WEEKEND...WITH DENSE FOG AND FREEZING RAIN ISSUES THIS MORNING
WITH THE FREEZING RAIN NOW LINGERING INTO THE AFTERNOON AND
POSSIBLY TONIGHT...CONTINUED FLOODING CONCERNS...AND LASTLY
POTENTIAL SNOWFALL WHICH THE AXIS OF HEAVIEST SNOW STILL APPEARS
TO BE ACROSS THE NORTH AND NORTHWEST AREAS OF THE CWA.
ADDRESSING THE MORE IMPORTANT ISSUES IN THE NEAR TERM...LIGHT
FREEZING RAIN OR FREEZING DRIZZLE CONTINUES ACROSS THE ADVISORY
AREA THIS MORNING...WITH LIGHT RAIN OR DRIZZLE ONGOING FOR THE
REMAINDER OF THE CWA. BROAD SOUTHWESTERLY FLOW ALOFT CONTINUES TO
USHER SEVERAL WAVES OF ENERGY...WITH ELONGATED TROUGH OF LOW
PRESSURE EXTENDING FROM THE CENTRAL PLAINS UP THROUGH SOUTHERN
GREAT LAKES. AS THESE WAVES OF ENERGY/SPEED MAXES LIFT NORTHEAST
ACROSS THE REGION THIS MORNING...EXPECT THIS TROUGH OF LOW
PRESSURE TO LIFT EAST NORTHEAST TO CENTRAL ILLINOIS AND NORTHWEST
INDIANA THROUGH THE EARLY AFTERNOON. PRESENT LOW/MID LEVEL
CONVERGENCE WILL CONTINUE TO BE A PERSISTENT THROUGH THIS
PERIOD...WITH CURRENT UPSTREAM WAVE TO AID IN TIGHTENING LOW/MID
LEVEL BAROCLINIC ZONE. THIS WILL ENHANCE FRONTOGENTIC FORCING
ACROSS THE ADVISORY AREA...ALL AIDING IN CONTINUED PRECIP
DEVELOPMENT AT LEAST THROUGH EARLY AFTERNOON FOR THE ENTIRE CWA.
HAVE INCREASED POPS THIS MORNING AND EARLY AFTERNOON...BUT WONDER
IF AFTERNOON POPS WILL NEED TO BE RAISED EVEN FURTHER WITH SHORT
TERM GUIDANCE HINTING AT CONTINUED TO DEVELOPMENT EVEN INTO THE
LATE AFTERNOON. ALTHOUGH CURRENT ASSOCIATED BOUNDARY DRAPED ACROSS
EAST CENTRAL ILLINOIS AND NORTHWEST INDIANA DID MAKE SOME
NORTHWARD PROGRESSION EARLY THIS MORNING...FEEL THAT THIS
NORTHWARD MOVEMENT HAS ENDED AND WILL REMAIN SITUATED UNTIL
DROPPING SOUTH/SOUTHEAST OF THE CWA THIS AFTERNOON. GUIDANCE
HINTING AT SOME WEAK CAA TO BEGIN OCCURRING OVER THE NEXT SEVERAL
HOURS AND WITH LATEST RAP ANALYSIS ALREADY INDICATING THIS ACROSS
WESTERN ILLINOIS...FEEL PRETTY CONFIDENT WITH THIS TREND. THIS
WILL HELP TEMPS IN THE ADVISORY AREA TO HOVER JUST BELOW OR AT THE
FREEZING MARK THROUGH MOST OF TODAY. WITH THIS CONTINUED PRECIP
AND TEMP TRENDS...HAVE DECIDED TO EXTEND THE FREEZING RAIN
ADVISORY THROUGH THE AFTERNOON AND HAVE ALSO INCLUDED KANE COUNTY
IN THE ADVISORY AS WELL. WILL NEED TO ALSO MONITOR THE AFTERNOON
PERIOD FOR THE REMAINING CWA...AS COLD ADVECTION SHOULD HELP TEMPS
LOWER AROUND FREEZING INTO THE LATE AFTERNOON PERIOD. WITH PRECIP
POSSIBLY LINGERING...COULD SEE SOME POSSIBLE LIGHT ICING IN AREAS
OUTSIDE OF THE ADVISORY. ALTHOUGH TEMPS SHOULD BE MARGINAL...AND
AM NOT OVERLY CONCERNED AT THIS TIME.
WITH REGARDS TO THE DENSE FOG...WITH INCREASING MOISTURE IN THE
BOUNDARY LAYER THIS PAST EVENING DENSE FOG DEVELOPED ALONG TO THE
NORTH OF THIS BOUNDARY. MANY REPORTS OF DENSE FOR WERE RECEIVED
THIS PAST EVENING ACROSS NORTHWEST INDIANA...PRIMARILY FOR LAKE
AND PORTER COUNTIES IN INDIANA. WITH THE BOUNDARY SITUATED AND
EXPECTED TO REMAIN THIS WAY THROUGH THE REMAINDER OF THE
MORNING...FEEL CURRENT DENSE FOG ADVISORY FOR THESE LOCATIONS
REMAINS VALID. ALTHOUGH...SOUTHERN AREAS OF COOK COUNTY AND
EASTERN AREAS OF WILL COUNTY WILL NEED TO BE MONITORED OVER THE
NEXT COUPLE OF HOURS AS VIS IN THESE LOCATIONS CONTINUES TO BOUNCE
AROUND 1/2 MILE. END TIMING FOR THIS DENSE FOG ADVISORY REMAINS 9
AM CST...AND SEEMS REASONABLE. THIS SAGGING BOUNDARY AND SLIGHTLY
DRIER AIR SHOULD HELP WITH THE MORE DENSE FOG...BUT WITH PATCHY
DENSE FOG STILL NOT OUT OF THE QUESTION AT LEAST THROUGH MID DAY.
CONFIDENCE WITH THIS FOG REMAINS LOW AT THIS TIME AND WILL NEED TO
MONITOR...POSSIBLY EXTENDING THIS ADVISORY OR MAYBE EVEN EXPANDING
IT LATER THIS MORNING.
WITH SURFACE LOW EXITING TO THE EAST THIS EVENING AND THE ARRIVAL
OF DRIER AIR...SHOULD OBSERVE OVERALL PRECIP CHANCES TO WIND DOWN
FOR THE TIME BEING. ALTHOUGH WITH GUIDANCE CONTINUING TO INDICATE
BROAD SCALE LIFT WITH THE APPROACHING LONGWAVE TROUGH TO THE WEST
IT DOES APPEAR AS IF AREAS ACROSS THE SOUTHERN CWA COULD SEE
ADDITIONAL PRECIP TONIGHT. ALTHOUGH LIGHT PRECIP...THERMAL
PROFILES WOULD INDICATE THAT THIS PRECIP WOULD BE IN THE FORM OF
LIGHT FREEZING RAIN OR LIGHT FREEZING DRIZZLE. ANOTHER PERIOD I AM
CONCERNED ABOUT AT THIS TIME IS LATE TONIGHT INTO EARLY SATURDAY
MORNING...ONCE AGAIN FOR AREAS ACROSS THE SOUTHERN CWA. WILL NEED
TO MONITOR SURFACE TEMP TRENDS ACROSS EAST CENTRAL ILLINOIS DURING
THIS TIME...WITH FREEZING RAIN ONCE AGAIN POSSIBLY BEING AN ISSUE.
EXPANDING PRECIP TO THE SOUTH IS EXPECTED TO INCH FURTHER NORTH
TOWARDS THE SOUTHERN CWA TOWARDS THE 12Z SATURDAY TIME
FRAME...WITH SOUTHWEST FLOW ALOFT PERSISTING OUT AHEAD OF THE
APPROACHING LONGWAVE TROUGH. WITH A SLOW TEMP TREND EXPECTED
SATURDAY MORNING...A PERIOD OF LIGHT FREEZING RAIN COULD CAUSE
SOME ISSUES PRIMARILY SOUTH OF I-80.
WITH REGARDS TO WINTER STORM SATURDAY THROUGH SUNDAY...LATEST
THINKING/UPDATES TO FORECAST CONTINUE TO SUPPORT CURRENT WINTER
STORM WATCH ACROSS NORTHERN PORTIONS OF THE CWA. EXPECTED VARYING
PRECIP TYPES INCLUDING ALMOST ALL WINTER PRECIP TYPES COULD BE
OBSERVED SATURDAY INTO SATURDAY NIGHT...WITH A VARYING THERMAL
PROFILE EXPECTED TO CHANGE THROUGH THE PERIOD FOR ALL AREAS. WILL
NEED TO MONITOR THE SATURDAY MORNING TIME FRAME INTO THE DAY
SATURDAY FOR THE VARYING PREICP TYPE...POSSIBLY ADDING YET ANOTHER
HEADLINE TO ACCOMMODATE FOR THE WINTRY MIX. EXPECTED SURFACE LOW
TRACK STILL SUPPORTIVE FOR BEST CHANCES FOR SNOW OR ALL SNOW
ACROSS NORTHWEST AND NORTH CENTRAL ILLINOIS WITH SNOWFALL TOTALS
IN EXCESS OF 6 INCHES STILL APPEARING POSSIBLE. THE EXPECTED RAIN
SNOW LINE HAS VARIED SLIGHTLY...BUT THE GENERAL IDEA REMAINING THE
SAME. OHARE TO PERU ILLINOIS LINE ARE THE DIVIDING LINE AT THIS
TIME...WITH CURRENT SNOW FORECAST INDICATING RAPID INCREASE IN
SNOW AMOUNTS RIGHT TO THE NORTH OF THIS LINE AND WITH AREAS TO THE
SOUTH OBSERVING LIGHT SNOW ACCUMULATIONS.
ALTHOUGH LATEST TRENDS ARE INDICATING THAT THE AXIS OF HEAVIEST
RAINFALL IS BEGINNING TO SHIFT SOUTH OF THE CWA...DECENT RAINFALL
AMOUNTS OF UP TO AN INCH STILL SUPPORT THE POSSIBILITY OF
FLOODING...AND HAVE MADE NO CHANGES TO THE CURRENT FLOOD WATCH.
RODRIGUEZ
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* CIG/VSBY TRENDS THROUGH THE DAY WITH IFR CONTINUING. DENSE FOG
IN CLOSE PROXIMITY TO MDW WITH 1/4-1/2SM VSBY STILL POSSIBLE
THROUGH DAYBREAK.
* PERIODIC -RA/DZ THROUGH MIDDAY WITH LOW CHANCE FOR SOME
-FZRA/FZDZ THIS AFTERNOON...MAINLY A ORD.
* NORTH TO NORTH-NORTHEAST WINDS INCREASING TO AROUND 10 KT THEN
TURNING NORTHWEST THIS EVENING.
MDB
//DISCUSSION...UPDATED 09Z...
WARM FRONTAL BOUNDARY HAS BEEN OSCILLATING NORTH AND SOUTH OVER A
NARROW CORRIDOR FROM ROUGHLY KGBG TO KGYY AND SOUTHERN LOWER
MICHIGAN THE PAST FEW HOURS. THIS HAS RESULTED IN A SOMEWHAT
TRANSIENT BAND OF DENSE FOG WHICH AS BEEN AFFECTING MDW AND GYY AT
TIMES. A LOOK AT AREA WEBCAMS AND SURFACE OBS SHOWS THAT THERE HAS
BEEN SOME SLIGHT IMPROVEMENT IN VSBY RIGHT ALONG THE BOUNDARY BUT
THIS MAY BE DUE TO THE BAND OF DENSE FOG MOVING BACK AND FORTH VS.
ANY CHANGE IN LOWEST VSBYS. EXPECT THAT THE BOUNDARY WILL MEANDER
THROUGH DAYBREAK LEAVING MDW/GYY IN A VARIABLE VSBY SITUATION AND
CANNOT RULE OUT A RETURN TO 1/4-1/2SM VSBY FOR AT LEAST A SHORT
TIME. THE BOUNDARY DOES LOOK TO PUSH SOUTH LATER THIS MORNING AS
SURFACE LOW PRESSURE MOVES NORTHEAST ALONG IT. THIS SHOULD ALLOW
NORTHERLY WINDS TO SET UP WITH COOLER AIR SPREADING SOUTH WHICH
SHOULD HELP VSBY. MAY BE TOUGH TO LOSE THE IFR CIGS BUT MVFR VSBY
LOOKS TO OCCUR TOWARD/DURING THE AFTERNOON AT SOME POINT.
OTHERWISE PERIODS OF -RA/DZ WILL CONTINUE THROUGH THE MORNING.
MDB
FROM 06Z...
MESSY CONDITIONS CONTINUE ACROSS THE TERMINALS TONIGHT WITH A
FRONTAL BOUNDARY STRETCHING FROM LOW PRESSURE OVER OKLAHOMA TO
ROUGHLY A KEOK TO KC75 TO KVPZ LINE. ABUNDANT MOISTURE AND LIFT
CONTINUE OVER THE BOUNDARY BRINGING RAIN SHOWERS AND AREAS OF
DRIZZLE TO THE TERMINALS. VSBY IS LOWEST RIGHT ALONG THE BOUNDARY
WITH GYY AROUND 1/4SM AND THIS WILL LIKELY PERSIST AS LONG AS THE
BOUNDARY IS NEARBY...WHICH AT THIS POINT LOOKS TO BE FOR MUCH OF
THE OVERNIGHT. AREAS NORTH HAVE SEEN VSBY GENERALLY AROUND A MILE
AND THIS SHOULD BE THE TREND THROUGH THE NIGHT...THOUGH THERE MAY
BE SOME DOWNWARD FLUCTUATIONS AT TIMES. CIGS SHOULD STAY STEADY
IN THE 002-004 RANGE THROUGH THE NIGHT AS WELL. RFD MAY SEE SOME
FREEZING RAIN/FREEZING DRIZZLE OVERNIGHT AS TEMPS COOL SLIGHTLY.
THINGS BECOME LESS CERTAIN AFTER DAYBREAK. THE LOW WILL TRACK
NORTHEAST TO NORTH-CENTRAL INDIANA BY FRIDAY AFTERNOON TURNING
WINDS FROM NORTHEAST TO NORTH-NORTHWEST THROUGH THE AFTERNOON. THE
MAIN QUESTION WILL BE HOW QUICKLY AND TO WHAT EXTENT CIGS/VSBY
IMPROVE. WITH THE BOUNDARY STILL IN THE AREA THROUGH THE MORNING
WILL ONLY HAVE VERY MINOR INCREASES IN CIGS/VSBY WITH BETTER
INCREASES DURING THE AFTERNOON AS COLDER AIR FILTERS INTO THE
REGION. SHOWERS/DRIZZLE WILL CONTINUE PERIODICALLY BEFORE TAPERING
OFF DURING THE AFTERNOON. RFD WILL HAVE THE BEST CHANCE OF SEEING
FREEZING RAIN THROUGH THE MORNING...WITH A LOW CHANCE THAT SOME
LIGHT FREEZING RAIN OR FREEZING DRIZZLE WILL MAKE IT INTO THE
CHICAGO TERMINALS DURING THE EARLY AFTERNOON AS COLDER AIR
ARRIVES. MVFR AND POSSIBLY IFR LOOK TO BE IN PLACE FOR FRIDAY
EVENING WITH NORTH-NORTHWEST WINDS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN IFR CONTINUING WITH LOWEST CONDITIONS THROUGH
DAYBREAK. LOW CONFIDENCE WITH SPEED/MAGNITUDE OF CIG/VSBY
IMPROVEMENT THROUGH THE DAY.
* HIGH CONFIDENCE IN PRECIP WINDING DOWN THIS AFTERNOON...MEDIUM-
HIGH CONFIDENCE THAT THREAT FOR -FZRA/FZDZ AT ORD IS LOW.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SAT...WINTRY MIX OF PRECIP FROM MIDDAY ON...WITH A CHANCE OF A
PERIOD OF FREEZING RAIN DURING THE NIGHT. MVFR TO IFR.
SUN...SNOW. MVFR TO IFR.
MON...MVFR CIGS. CHANCE OF SNOW SHOWERS WITH IFR.
TUE...VFR.
WED...VFR BECOMING MVFR CIGS.
THU...MVFR CIGS IMPROVING TO VFR.
TRS
&&
.MARINE...
301 AM CST
LOW PRESSURE CENTERED OVER NORTH-CENTRAL OKLAHOMA WILL TRACK
NORTHEAST ALONG A FRONTAL BOUNDARY WHICH EXTENDS NORTHEAST INTO
NORTHERN INDIANA AND EASTWARD ACROSS LAKE ERIE AND ONTARIO.
MEANWHILE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE LITTLE
THROUGH THE DAY. THE STRONGEST PRESSURE GRADIENT IS STARTING TO SET
UP EARLY THIS MORNING AND WILL LIKELY RESULT IN AN INCREASE IN
NORTHEAST WINDS ACROSS MUCH OF THE LAKE THROUGH MID MORNING BEFORE
THE PRESSURE GRADIENT EASES. SPEEDS MAY PUSH 30 KT FOR A TIME
THROUGH MID OR LATE MORNING...ESPECIALLY ACROSS CENTRAL SECTIONS OF
THE LAKE. THE LOW WILL PASS SOUTH OF THE LAKE LATER THIS AFTERNOON
AND BEGIN TO WEAKEN WITH THE HIGH WEAKENING AS WELL. ANOTHER SURFACE
LOW WILL DEVELOP OVER THE ARKLATEX SATURDAY AND LIFT NORTHEAST TO
NORTHERN OHIO BY SUNDAY AFTERNOON. A VERY STRONG HIGH WILL THEN
DEVELOP SOUTHWARD INTO THE NORTHERN PLAINS AS THE LOW MOVES INTO NEW
ENGLAND SUNDAY NIGHT. THIS WILL LEAVE LAKE MICHIGAN IN THE PRESSURE
GRADIENT BETWEEN THE TWO SYSTEMS SATURDAY NIGHT AND SUNDAY WITH
COLDER AIR SPILLING ACROSS THE LAKE AS WELL. THIS WILL SET THE STAGE
FOR ANOTHER ROUND OF STRONG WINDS WHICH WILL START OUT NORTHEAST
THEN SHIFT NORTH-NORTHWEST AND EASE UP LATE SUNDAY AFTERNOON. THE
HIGH WILL PASS SOUTH OF THE LAKE TUESDAY BEFORE LOW PRESSURE TRACKS
SOUTHEAST ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THIS
SHOULD LEAD TO ANOTHER PERIOD OF INCREASED WINDS...THIS TIME FROM
THE SOUTH AND SOUTHWEST WEDNESDAY. WILL KEEP SPEEDS BELOW GALE FORCE
THROUGH THE PERIOD BUT WILL NEED TO MONITOR FOR SHORT WINDOWS OF
GALE FORCE WINDS SATURDAY NIGHT AND SUNDAY MORNING...AND AGAIN EARLY
WEDNESDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011 UNTIL NOON FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740...9 AM FRIDAY TO 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 AM FRIDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
318 AM CST FRI DEC 20 2013
.DISCUSSION...
813 PM CST
FOR EVENING UPDATE...
MOVED UP START AND EXPANDED SLIGHTLY FREEZING RAIN ADVISORY FOR
FAR NORTH AND NORTH CENTRAL IL TONIGHT-FRIDAY. HAVE ALSO MADE SOME
ADJUSTMENTS TO WEEKEND STORM SYSTEM AS OUTLINED BELOW.
TONIGHT/FRIDAY...
HAVE SLIGHTLY EXPANDED AND STARTED THE FREEZING RAIN ADVISORY
EARLIER TONIGHT AS TEMPERATURES HOVER RIGHT AROUND 32F ACROSS
NORTH CENTRAL AND FAR NORTHEAST ILLINOIS...AND A REPORT OF A LIGHT
GLAZE HAS ALREADY BEEN RECEIVED FROM THE NORTHWEST SIDE OF ROCKFORD.
EVENING GOES WATER VAPOR LOOP DEPICTS A SHORT WAVE CENTER NEARING
THE OZARKS IN THE BROAD MOIST WSW FLOW OVER THE AREA. THIS FEATURE
HAS LED TO AN EXPANSION IN LOW CLOUDS AS WELL AS LIGHT RAIN/DRIZZLE
ACROSS NORTHEAST MO...EASTERN IA...SOUTHERN WI...AND NORTHWEST AND
NORTH CENTRAL IL. THE 00Z DVN SOUNDING SHOWED 25-35KT OF
SOUTHWESTERLY FLOW WITHIN A SATURATED LAYER FROM 750MB TO THE
SURFACE. THE MIN TEMP OBSERVED IN THAT LAYER OF ONLY -1C...SO
CERTAINLY NO ICE CRYSTALS INVOLVED. THE RAP APPEARS TO ANALYZE THIS
WELL AT 285K-290K WITH SATURATED ISENTROPIC ASCENT ACROSS NORTHERN
IL INTO OVERNIGHT...AND THE CONVERGENCE OF THE LOW-LEVEL BOUNDARY
DRAPED ACROSS THE AREA HELPING TO POOL MOISTURE/SATURATION.
THE SURFACE STATIONARY BOUNDARY IS ARCED FROM SOUTH OF PERU TO THE
SOUTH SIDE OF CHICAGO. FOR TEMPERATURES...BELIEVE THAT NORTH OF THE
BOUNDARY WILL BASICALLY HOLD STEADY OR EASE DOWNWARD...WHILE SOUTH
OF THERE MAY EVEN KEEP INCHING UP. FOR POINTS NORTH...THIS CREATES
AN EARLIER AND PROBABLY BETTER POTENTIAL FOR LIGHT ICING THAN
ORIGINALLY FORECAST...AS TEMPS ACROSS NORTH CENTRAL IL ARE ALREADY
32-33F. SO HAVE EXPANDED FREEZING RAIN DEPICTION IN THE GRIDS AND
AGAIN STARTED THE ADVISORY EARLIER.
SATURDAY/SUNDAY...
HAVE MADE ADJUSTMENTS TO THE FORECAST GRIDS FOR SATURDAY INTO SUNDAY
BASED ON MODEL THERMAL PROFILES AND SOUNDINGS...PARTICULARLY THE
1000-850 MB CRITICAL THICKNESS (1300 DM) WHICH IS A KEY INDICATOR
FOR SNOW VERSUS RAIN/ZR/SLEET. THE GFS RUNS TODAY WERE THE COLDEST
WITH THE NAM/ECMWF SHOWING A MUCH MORE DISTINCT WARM NOSE AT 850
MB...BUT EVEN THE GFS WOULD ONLY FAVOR THE FAR NORTHERN CWA FOR A
WINTRY MIX TRANSITIONING TO SNOW/SLEET AND THEN ALL SNOW ON SATURDAY
NIGHT WHERE THERE IS THE BEST OVERLAP WITH FORCING AND LIFT THROUGH
THE DGZ. IN BETWEEN THE FAVORED AREA FOR MORE SIGNIFICANT SNOW/SLEET
ACCUMS AND MAINLY RAIN OVER THE SOUTHEAST HALF OF THE CWA...HAVE
INDICATED A TRANSITION ZONE WHERE A MIXED BAG INCLUDING FREEZING
RAIN IS POSSIBLE. AM CONCERNED THAT IF P-TYPE IS MAINLY ZR FOR A
TIME...THERE COULD BE DECENT ICE ACCRETION...AND THIS WOULD
INCLUDE PARTS OF THE WEST AND NORTHWEST CHICAGO METRO.
FINALLY...SUNDAY MORNING IT APPEARS THAT ALL BUT THE SOUTHEAST
THIRD OF THE CWA WILL TRANSITION OVER TO ALL SNOW AS COLDER AIR
PUSHES IN ALOFT.
THE TWEAKS TO QPF AND WEATHER TYPES AND SNOW AMOUNT GRIDS RESULTED
IN A MUCH TIGHTER SNOWFALL GRADIENT...WITH POTENTIAL FOR AMOUNTS IN
EXCESS OF 6 INCHES IN NORTH CENTRAL/NW AND EXTREME NORTHEASTERN
ILLINOIS...QUICKLY TAPERING TO THE SOUTHEAST. LITTLE OR NO SNOW
ACCUMULATION IS ANTICIPATED IN THE SOUTHEAST THIRD OF THE CWA.
NEEDLESS TO SAY...THIS IS STILL A FLUID SITUATION AND SMALL CHANGES
IN THE TRACK OF THE LOW PRESSURE SYSTEM AND THERMAL PROFILES WILL
HAVE LARGE IMPLICATIONS IN PRECIPITATION TYPE AND AMOUNTS. HAVE MADE
NO CHANGES TO THE WINTER STORM WATCH AND FLOOD WATCH IN EFFECT.
MTF/RC/RATZER
//PREV DISCUSSION...
UPDATED...415 PM CST FOR THIS WEEKEND PORTION
TONIGHT THROUGH FRIDAY NIGHT
UPDATED...1224 PM CST
FRONTAL BOUNDARY IS DRAPED FROM THE CHICAGO METRO AREA WSW TO NEAR
THE QUAD CITIES THIS AFTERNOON. ASCENT IS FORECAST TO INCREASE THIS
EVENING AND TONIGHT ON TOP OF THE BOUNDARY WHICH WILL MEANDER SOME
AS THE SURFACE WAVE LIFTS ACROSS THE REGION. WARM ADVECTION ALOFT
LEAVES LITTLE DOUBT THAT PRECIP WILL MELT ALOFT WITH 3-4C SATURATED
WARM LAYER TEMPS AS FAR NORTH AS THE WI STATE LINE. THE BIG CONCERN
WILL BE SURFACE/GROUND TEMPERATURE TRENDS. TEMPERATURES ARE
EXPECTED TO MOSTLY HOLD STEADY INTO THE LATE EVENING...THEN COLDER
//BELOW FREEZING// SURFACE TEMPS WILL START TO TRICKLE SOUTHEAST
INTO FAR NORTHERN IL AS THE LOW STARTS TO PASS TO OUR SOUTH.
CURRENTLY IT APPEARS THAT ONLY THE FAR REACHES OF THE CWA...
INCLUDING PORTIONS OF OGLE...WINNEBAGO...BOONE...AND MCHENRY
COUNTIES...WILL SEE SURFACE TEMPERATURES FALLING BELOW FREEZING
OVERNIGHT AND WHERE THE CONCERN FOR LIGHT FREEZING RAIN AND LIGHT
ICE ACCUMULATIONS WILL BE. A FREEZING RAIN ADVISORY HAS BEEN ISSUED
FOR THESE COUNTIES...AND EXPECT A GLAZE UP TO A TENTH OF AN INCH OF
ICE FOR THESE AREAS.
BY MID MORNING FRIDAY...TEMPERATURES ARE EXPECTED TO CONTINUE TO
SLOWLY FALL WITH THE LOW DEPARTING EAST. FORCING QUICKLY TAPERS BUT
PERSISTENT LOW LEVEL MOISTURE AND WEAK OMEGA RAISES THE CONCERN FOR
FREEZING DRIZZLE TO SPREAD SOUTH OF THE CURRENT ADVISORY
AREA...PERHAPS AS FAR SOUTH AS THE I-80 CORRIDOR. MID/HIGH LEVEL
MOISTURE WILL BE PRESENT...HOWEVER MID LEVEL DRY LAYER IS EXPECTED
TO INHIBIT SEEDER/FEEDER FROM INTRODUCING ICE INTO THE LOW LEVEL
MOISTURE LAYER...WHICH ONLY HAS TEMPERATURES AS COOL AS -5C.
SURFACE TEMPERATURES WILL BE RIGHT AROUND THE FREEZING MARK. FOR
NOW PLAN ON HIGHLIGHTING AREA WITH AN SPS...AND CANNOT RULE OUT
EXPANSION OF ADVISORY FARTHER SOUTH LATER INTO THE DAY FRIDAY IF
IT APPEARS TEMPERATURES WILL BE COOLER OR IF PRECIP MORE ROBUST.
DEUBELBEISS
FOR THE WEEKEND...
UPDATED...415 PM CST...
A VERY ACTIVE WEATHER PATTERN IS SETTING UP...WITH A FLOOD WATCH
ISSUED FOR THE SOUTHEASTERN PORTIONS OF THE CWA AND A WINTER STORM
WATCH ISSUED FOR THE NORTHERN AND NORTHWESTERN PORTIONS OF THE
CWA.
THE FIRST AREA OF CONCERN WILL BE THE POTENTIAL FOR HEAVY RAINFALL
OVER AT LEAST PORTIONS OF THE AREA. HAVE BEEN MONITORING THE
DEVELOPMENT OF A SOUTHERN STREAM SYSTEM OVER THE SOUTH HIGH PLAINS.
AS OF THURSDAY AFTERNOON...THE SYSTEM IS MOVING ONSHORE INTO
SOUTHERN CALIFORNIA AND WILL FINALLY BE SAMPLED BY THE UPPER AIR
DATA NETWORK. WHILE THE MODELS HAVE PROVIDED A MYRIAD OF SOLUTIONS
FOR THE TRACK OF THIS SYSTEM...MUCH OF THE VIABLE GUIDANCE LOOKED AT
TODAY IS CONVERGING ON THE "WARMER" SOLUTION FOR THE LOCAL
AREA...WITH THE EXCEPTION OF THE GFS WHICH IS THE OUTLIER...PUSHING
THE SYSTEM TO FAR EAST...TOO FAST. THE CONVERGED SOLUTION WILL
TRACK A SERIES OF WAVES ALONG A WARM FRONT DEVELOPING FROM THE SOUTH
HIGH PLAINS INTO NORTHERN ILLINOIS. WARM AIR...MOIST AIR...WITH
TEMPS IN THE UPPER 30S AND DEW POINTS IN THE LOWER TO MIDDLE 30S HAS
ALREADY OVERSPREAD MUCH OF THE AREA. THE WARM FRONT WILL MEANDER
OVER THE AREA AS THE MAIN SFC LOW DEEPENS AND TRACKS ALONG THE
BOUNDARY...CROSSING THE MIDDLE MISSISSIPPI VALLEY BY FRIDAY
MORNING. BY FRIDAY MORNING...THE WARM FRONT SHOULD LAY RIGHT
THROUGH THE MIDDLE OF THE CWA...WITH TEMPS IN THE LOWER 30S ALONG
THE WISCONSIN BORDER...WITH LOWER 40S OVER LOCATIONS SOUTH OF THE
ILLINOIS AND KANKAKEE RIVERS. AS THE SFC LOW TRACKS NEWD ALONG THE
PATH OF THE FRONTAL TROUGH...HIGH PRESSURE WILL BE MOVING OFF THE
SERN COAST. THIS WILL SET UP A WIDE OPEN GULF OF MEXICO...WITH
COPIOUS AMOUNTS OF MOISTURE STREAMING NWD. PWATS ARE FORECAST TO
RISE TO 1.0 TO 1.5 INCHES OVER THE SERN PORTIONS OF THE CWA RIDING
ON A STRONG LOW LEVEL JET...WITH MAX 850MB WINDS OVER 60-70KT.
WHILE THE STRONGEST OF THE LOW LEVEL JET WILL BE TO THE
SOUTH...MOSTLY OVER THE OHIO VALLEY...THERE WILL BE AMPLE ISENTROPIC
LIFT AND MOISTURE TRANSPORT TO SUPPORT AREAS OF HEAVY RAINFALL. AT
THIS POINT...IT LOOKS LIKE THE HEAVIEST RAIN WILL BE OVER THE SERN
PORTIONS OF THE CWA...OUTLINED IN THE FLOOD WATCH ISSUED THIS
AFTERNOON. HOWEVER...THE HEAVY RAIN WILL NOT BE THE ONLY PROBLEM.
WITH COOLER AIR REMAINING AT THE SFC NORTH OF THE WARM FRONT...THE
STRONG ISENTROPIC LIFT ALONG AND NORTH OF THE BOUNDARY WILL FORCE
THE WARMER AIR OVER THE COOLER AIR AT THE SFC...SETTING UP A PERIOD
OF MIXED FREEZING AND FROZEN PCPN. THE EXACT LOCATION OF THE WINTRY
MIX OF PCPN STILL REMAINS A LITTLE TOUGH TO NARROW DOWN...BUT MOST
OF THE AREA NORTH OF THE KANKAKEE AND ILLINOIS RIVERS WILL SEE A
LEAST SOME PERIODS OF THE WINTRY MIX PCPN...WITH THE ROCKFORD AREA
LIKELY NOT SEEING ANY LIQUID WHILE THE CHICAGO METRO SHOULD SEE SOME
AND AND SOME OF THE WINTRY MIX.
AS THE HEAVY RAIN SITUATION IS WINDING DOWN SATURDAY NIGHT OR EARLY
SUNDAY MORNING...THE MAIN FORECAST CONCERN WILL SHIFT TO THE
POTENTIAL FOR HEAVY SNOWFALL. THE SRN STREAM SYSTEM NOT ONLY WILL
BE RESPONSIBLE FOR DRAWING MOISTURE NORTHWARD...THERE SHOULD BE SOME
PHASING WITH A NORTHERN STREAM SHORTWAVE DROPPING OUT OF THE NRN
PLAINS. THIS SHOULD LEAD TO THE DEVELOPMENT OF A WEAK SECONDARY
CIRCULATION OVER NRN IL BY SUNDAY MORNING...ENHANCING THE DRAW OF
COOLER AIR FROM THE NORTH. THE STRONGER COLD ADVECTION AND A STRONG
DEFORMATION ZONE ARE ADVERTISED TO SET UP OVER NRN IL/SRN WI WHICH
WILL BE THE PRIMARY FOCUSING ELEMENTS FOR A BAND OF HEAVY SNOW. AT
THIS POINT...BASED ON THE GOOD CONSENSUS OF THE NAM AND
ECMWF...WHICH WOULD WOULD INDICATE AN AXIS OF HEAVIER SNOW GENERALLY
FROM ERN IOWA TO SERN WISCONSIN. ALL THINGS CONSIDERED...CONFIDENCE
IS BECOMING HIGH ENOUGH FOR IN EXCESS OF 6 INCHES OF SNOW OVER THE
NRN AND NWRN PORTIONS OF THE CWA...AS OUTLINED IN THE WINTER STORM
WATCH ISSUED THIS AFTERNOON. CURRENTLY ANTICIPATE THAT THE ENTIRE
CWA WILL SEE AT LEAST SOME SNOW...WITH 2 TO 4 INCHES ALONG A LINE
FROM CHICAGO TO PONTIAC AND 1 TO 2 INCHES FROM VALPARAISO TO
PONTIAC...TAPERING OFF TO AN INCH OR LESS OVER THE FAR SERN PORTIONS
OF THE CWA.
AK
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...
UPDATED 316 PM CST
SUNDAY NIGHT...
GUIDANCE CONTINUES TO BE CONSISTENT IN DELIVERING A SHOT OF ARCTIC
AIR IN THE WAKE OF THE SIGNIFICANT WEEKEND STORM. A NORTHERN STREAM
TROUGH CURRENTLY NEAR THE NORTH POLE WILL DIG IN OVER THE NORTH
CENTRAL CONUS COUPLED WITH A ~1040 MB HIGH DROPPING SOUTH FROM THE
NORTHERN PLAINS. ALL OF THE SYSTEM SNOWS SHOULD BE OFF TO THE EAST
SUNDAY NIGHT...BUT POSITIVE VORTICITY ADVECTION FROM SHORT WAVES
ROTATING AROUND DEEP UPPER TROUGH COULD SQUEEZE OUT SOME LIGHT SNOW
OR FLURRIES IN THE ARCTIC AIR MASS. THE ECMWF CONTINUES TO BE MOST
BULLISH IN SQUEEZING OUT LIGHT QPF OVER THE AREA. THERE ALSO COULD
BE A BRIEF PERIOD OF FAVORABLE LAKE EFFECT CONDITIONS FOR PORTIONS
OF NW INDIANA DEPENDING ON IF WINDS CAN REMAIN CLOSER TO DUE NORTH
BEFORE BACKING WEST NORTHWEST. TEMPERATURES WILL PLUMMET IN STRONG
COLD ADVECTION BUT PERSISTENT NW WINDS AND CLOUD COVER COULD LIMIT
HOW FAR THEY FALL. WITH THE RAPIDLY FALLING TEMPERATURES SUNDAY
NIGHT...THERE COULD VERY WELL BE A FLASH FREEZE OF ANY REMAINING
MOISTURE ON THE GROUND.
MONDAY...
MAINTAINED A SLIGHT CHANCE OF FLURRIES ON MONDAY MORNING AS THE DEEP
UPPER TROUGH WILL BE OVERHEAD AND IT MAY NOT BE HARD TO SQUEEZE OUT
DENDRITES DESPITE THE COLD DRY AIR MASS. ALSO GUIDANCE INDICATES A
FAIRLY STOUT WAVE FOCUSED INTO THE NORTHEAST CWA AND WISCONSIN...SO
FELT COMFORTABLE WITH THE SLIGHT CHANCE POP FROM GUIDANCE BLEND
INITIALIZATION FOR NORTHEAST IL AND EXTREME NW INDIANA. HIGH
TEMPERATURES MONDAY AND LOWS MONDAY NIGHT WILL BE COLD
EVERYWHERE...BUT HOW COLD WILL DEPEND ON WHICH AREAS MAINTAIN
SUBSTANTIAL SNOW PACK AFTER THE WEEKEND SYSTEM. AT THIS TIME...IT
APPEARS THAT THE NORTHERN CWA WOULD HAVE THE BEST CHANCE. WITH
SURFACE HIGH BEING NEAR OR OVER THE AREA AND NO MORE THAN PARTLY
CLOUDY SKIES EXPECTED...DROPPED LOW TEMPERATURES MONDAY NIGHT FROM
PREVIOUS FORECAST TO 5 TO 10 BELOW WEST OF THE FOX VALLEY. STAYED
MORE CONSERVATIVE IN THE SOUTHERN CWA WHERE LITTLE OR NO SNOW COVER
SHOULD BE LEFT. TO NOTE...THE ECMWF AND GFS WHICH HAVE CLEAR SKIES
HAVE LOWS IN THE COLDEST SPOTS 10 DEGREES COLDER THAN IN FORECAST
GRIDS...WHILE CANADIAN MODEL KEEPS CLOUD COVER AND IS A GOOD DEAL
WARMER.
TUESDAY NIGHT THROUGH THURSDAY...
AFTER A BITTERLY COLD START TO CHRISTMAS EVE DAY...SOUTHWEST WARM
ADVECTION BEHIND TROUGH DEPARTING TO THE EAST WILL ENABLE A DECENT
AFTERNOON TEMPERATURE RECOVERY...BUT STILL WELL BELOW CLIMO. COULD
SEE TEMPERATURES BEING A BIT WARMER THAN CURRENTLY FORECAST IN AREAS
WITHOUT SNOW COVER. WILL HAVE TO WATCH FOR A NORTHERN STREAM WAVE
BEING A BIT FARTHER SOUTH THAN MODEL CONSENSUS ON CHRISTMAS EVE
NIGHT...BUT WITH ECMWF TRENDING SOUTH...INDICATED A SLIGHT CHANCE OF
LIGHT SNOW NEAR THE WISCONSIN BORDER. THIS FEATURE COULD THEN GO ON
TO RESULT IN AT LEAST SOME LIGHT SNOW OR FLURRIES IN THE AIR FOR THE
ENTIRE AREA ON CHRISTMAS DAY. THIS WOULD BE A CONSOLATION PRIZE FOR
AREAS THAT LOSE THEIR SNOW COVER THIS WEEKEND...BUT FOR AREAS THAT
KEEP AT LEAST 1 INCH OF SNOW ON THE GROUND...A WHITE CHRISTMAS IS
HIGHLY LIKELY. TEMPERATURES WILL MODERATE TO NEAR NORMAL ON
CHRISTMAS DAY...WITH ANOTHER SHOT OF ARCTIC AIR POSSIBLE ON THURSDAY
BEHIND THE CHRISTMAS DAY SYSTEM.
CONFIDENCE IN A WHITE CHRISTMAS FOR AREAS THAT MAINTAIN AT LEAST 1
INCH OF SNOW COVER THIS WEEKEND...HIGH.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 09Z...
* CIG/VSBY TRENDS THROUGH THE DAY WITH IFR CONTINUING. DENSE FOG
IN CLOSE PROXIMITY TO MDW WITH 1/4-1/2SM VSBY STILL POSSIBLE
THROUGH DAYBREAK.
* PERIODIC -RA/DZ THROUGH MIDDAY WITH LOW CHANCE FOR SOME
-FZRA/FZDZ THIS AFTERNOON...MAINLY A ORD.
* NORTH TO NORTH-NORTHEAST WINDS INCREASING TO AROUND 10 KT THEN
TURNING NORTHWEST THIS EVENING.
MDB
//DISCUSSION...UPDATED 09Z...
WARM FRONTAL BOUNDARY HAS BEEN OSCILLATING NORTH AND SOUTH OVER A
NARROW CORRIDOR FROM ROUGHLY KGBG TO KGYY AND SOUTHERN LOWER
MICHIGAN THE PAST FEW HOURS. THIS HAS RESULTED IN A SOMEWHAT
TRANSIENT BAND OF DENSE FOG WHICH AS BEEN AFFECTING MDW AND GYY AT
TIMES. A LOOK AT AREA WEBCAMS AND SURFACE OBS SHOWS THAT THERE HAS
BEEN SOME SLIGHT IMPROVEMENT IN VSBY RIGHT ALONG THE BOUNDARY BUT
THIS MAY BE DUE TO THE BAND OF DENSE FOG MOVING BACK AND FORTH VS.
ANY CHANGE IN LOWEST VSBYS. EXPECT THAT THE BOUNDARY WILL MEANDER
THROUGH DAYBREAK LEAVING MDW/GYY IN A VARIABLE VSBY SITUATION AND
CANNOT RULE OUT A RETURN TO 1/4-1/2SM VSBY FOR AT LEAST A SHORT
TIME. THE BOUNDARY DOES LOOK TO PUSH SOUTH LATER THIS MORNING AS
SURFACE LOW PRESSURE MOVES NORTHEAST ALONG IT. THIS SHOULD ALLOW
NORTHERLY WINDS TO SET UP WITH COOLER AIR SPREADING SOUTH WHICH
SHOULD HELP VSBY. MAY BE TOUGH TO LOSE THE IFR CIGS BUT MVFR VSBY
LOOKS TO OCCUR TOWARD/DURING THE AFTERNOON AT SOME POINT.
OTHERWISE PERIODS OF -RA/DZ WILL CONTINUE THROUGH THE MORNING.
MDB
FROM 06Z...
MESSY CONDITIONS CONTINUE ACROSS THE TERMINALS TONIGHT WITH A
FRONTAL BOUNDARY STRETCHING FROM LOW PRESSURE OVER OKLAHOMA TO
ROUGHLY A KEOK TO KC75 TO KVPZ LINE. ABUNDANT MOISTURE AND LIFT
CONTINUE OVER THE BOUNDARY BRINGING RAIN SHOWERS AND AREAS OF
DRIZZLE TO THE TERMINALS. VSBY IS LOWEST RIGHT ALONG THE BOUNDARY
WITH GYY AROUND 1/4SM AND THIS WILL LIKELY PERSIST AS LONG AS THE
BOUNDARY IS NEARBY...WHICH AT THIS POINT LOOKS TO BE FOR MUCH OF
THE OVERNIGHT. AREAS NORTH HAVE SEEN VSBY GENERALLY AROUND A MILE
AND THIS SHOULD BE THE TREND THROUGH THE NIGHT...THOUGH THERE MAY
BE SOME DOWNWARD FLUCTUATIONS AT TIMES. CIGS SHOULD STAY STEADY
IN THE 002-004 RANGE THROUGH THE NIGHT AS WELL. RFD MAY SEE SOME
FREEZING RAIN/FREEZING DRIZZLE OVERNIGHT AS TEMPS COOL SLIGHTLY.
THINGS BECOME LESS CERTAIN AFTER DAYBREAK. THE LOW WILL TRACK
NORTHEAST TO NORTH-CENTRAL INDIANA BY FRIDAY AFTERNOON TURNING
WINDS FROM NORTHEAST TO NORTH-NORTHWEST THROUGH THE AFTERNOON. THE
MAIN QUESTION WILL BE HOW QUICKLY AND TO WHAT EXTENT CIGS/VSBY
IMPROVE. WITH THE BOUNDARY STILL IN THE AREA THROUGH THE MORNING
WILL ONLY HAVE VERY MINOR INCREASES IN CIGS/VSBY WITH BETTER
INCREASES DURING THE AFTERNOON AS COLDER AIR FILTERS INTO THE
REGION. SHOWERS/DRIZZLE WILL CONTINUE PERIODICALLY BEFORE TAPERING
OFF DURING THE AFTERNOON. RFD WILL HAVE THE BEST CHANCE OF SEEING
FREEZING RAIN THROUGH THE MORNING...WITH A LOW CHANCE THAT SOME
LIGHT FREEZING RAIN OR FREEZING DRIZZLE WILL MAKE IT INTO THE
CHICAGO TERMINALS DURING THE EARLY AFTERNOON AS COLDER AIR
ARRIVES. MVFR AND POSSIBLY IFR LOOK TO BE IN PLACE FOR FRIDAY
EVENING WITH NORTH-NORTHWEST WINDS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 09Z...
* HIGH CONFIDENCE IN IFR CONTINUING WITH LOWEST CONDITIONS THROUGH
DAYBREAK. LOW CONFIDENCE WITH SPEED/MAGNITUDE OF CIG/VSBY
IMPROVEMENT THROUGH THE DAY.
* HIGH CONFIDENCE IN PRECIP WINDING DOWN THIS AFTERNOON...MEDIUM-
HIGH CONFIDENCE THAT THREAT FOR -FZRA/FZDZ AT ORD IS LOW.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SAT...WINTRY MIX OF PRECIP FROM MIDDAY ON...WITH A CHANCE OF A
PERIOD OF FREEZING RAIN DURING THE NIGHT. MVFR TO IFR.
SUN...SNOW. MVFR TO IFR.
MON...MVFR CIGS. CHANCE OF SNOW SHOWERS WITH IFR.
TUE...VFR.
WED...VFR BECOMING MVFR CIGS.
THU...MVFR CIGS IMPROVING TO VFR.
TRS
&&
.MARINE...
301 AM CST
LOW PRESSURE CENTERED OVER NORTH-CENTRAL OKLAHOMA WILL TRACK
NORTHEAST ALONG A FRONTAL BOUNDARY WHICH EXTENDS NORTHEAST INTO
NORTHERN INDIANA AND EASTWARD ACROSS LAKE ERIE AND ONTARIO.
MEANWHILE HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE LITTLE
THROUGH THE DAY. THE STRONGEST PRESSURE GRADIENT IS STARTING TO SET
UP EARLY THIS MORNING AND WILL LIKELY RESULT IN AN INCREASE IN
NORTHEAST WINDS ACROSS MUCH OF THE LAKE THROUGH MID MORNING BEFORE
THE PRESSURE GRADIENT EASES. SPEEDS MAY PUSH 30 KT FOR A TIME
THROUGH MID OR LATE MORNING...ESPECIALLY ACROSS CENTRAL SECTIONS OF
THE LAKE. THE LOW WILL PASS SOUTH OF THE LAKE LATER THIS AFTERNOON
AND BEGIN TO WEAKEN WITH THE HIGH WEAKENING AS WELL. ANOTHER SURFACE
LOW WILL DEVELOP OVER THE ARKLATEX SATURDAY AND LIFT NORTHEAST TO
NORTHERN OHIO BY SUNDAY AFTERNOON. A VERY STRONG HIGH WILL THEN
DEVELOP SOUTHWARD INTO THE NORTHERN PLAINS AS THE LOW MOVES INTO NEW
ENGLAND SUNDAY NIGHT. THIS WILL LEAVE LAKE MICHIGAN IN THE PRESSURE
GRADIENT BETWEEN THE TWO SYSTEMS SATURDAY NIGHT AND SUNDAY WITH
COLDER AIR SPILLING ACROSS THE LAKE AS WELL. THIS WILL SET THE STAGE
FOR ANOTHER ROUND OF STRONG WINDS WHICH WILL START OUT NORTHEAST
THEN SHIFT NORTH-NORTHWEST AND EASE UP LATE SUNDAY AFTERNOON. THE
HIGH WILL PASS SOUTH OF THE LAKE TUESDAY BEFORE LOW PRESSURE TRACKS
SOUTHEAST ACROSS THE CANADIAN PRAIRIES AND NORTHERN PLAINS. THIS
SHOULD LEAD TO ANOTHER PERIOD OF INCREASED WINDS...THIS TIME FROM
THE SOUTH AND SOUTHWEST WEDNESDAY. WILL KEEP SPEEDS BELOW GALE FORCE
THROUGH THE PERIOD BUT WILL NEED TO MONITOR FOR SHORT WINDOWS OF
GALE FORCE WINDS SATURDAY NIGHT AND SUNDAY MORNING...AND AGAIN EARLY
WEDNESDAY.
MDB
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011 UNTIL NOON FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740...9 AM FRIDAY TO 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 AM FRIDAY.
&&
$$
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AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1212 AM CST FRI DEC 20 2013
.DISCUSSION...
813 PM CST
FOR EVENING UPDATE...
MOVED UP START AND EXPANDED SLIGHTLY FREEZING RAIN ADVISORY FOR
FAR NORTH AND NORTH CENTRAL IL TONIGHT-FRIDAY. HAVE ALSO MADE SOME
ADJUSTMENTS TO WEEKEND STORM SYSTEM AS OUTLINED BELOW.
TONIGHT/FRIDAY...
HAVE SLIGHTLY EXPANDED AND STARTED THE FREEZING RAIN ADVISORY
EARLIER TONIGHT AS TEMPERATURES HOVER RIGHT AROUND 32F ACROSS
NORTH CENTRAL AND FAR NORTHEAST ILLINOIS...AND A REPORT OF A LIGHT
GLAZE HAS ALREADY BEEN RECEIVED FROM THE NORTHWEST SIDE OF ROCKFORD.
EVENING GOES WATER VAPOR LOOP DEPICTS A SHORT WAVE CENTER NEARING
THE OZARKS IN THE BROAD MOIST WSW FLOW OVER THE AREA. THIS FEATURE
HAS LED TO AN EXPANSION IN LOW CLOUDS AS WELL AS LIGHT RAIN/DRIZZLE
ACROSS NORTHEAST MO...EASTERN IA...SOUTHERN WI...AND NORTHWEST AND
NORTH CENTRAL IL. THE 00Z DVN SOUNDING SHOWED 25-35KT OF
SOUTHWESTERLY FLOW WITHIN A SATURATED LAYER FROM 750MB TO THE
SURFACE. THE MIN TEMP OBSERVED IN THAT LAYER OF ONLY -1C...SO
CERTAINLY NO ICE CRYSTALS INVOLVED. THE RAP APPEARS TO ANALYZE THIS
WELL AT 285K-290K WITH SATURATED ISENTROPIC ASCENT ACROSS NORTHERN
IL INTO OVERNIGHT...AND THE CONVERGENCE OF THE LOW-LEVEL BOUNDARY
DRAPED ACROSS THE AREA HELPING TO POOL MOISTURE/SATURATION.
THE SURFACE STATIONARY BOUNDARY IS ARCED FROM SOUTH OF PERU TO THE
SOUTH SIDE OF CHICAGO. FOR TEMPERATURES...BELIEVE THAT NORTH OF THE
BOUNDARY WILL BASICALLY HOLD STEADY OR EASE DOWNWARD...WHILE SOUTH
OF THERE MAY EVEN KEEP INCHING UP. FOR POINTS NORTH...THIS CREATES
AN EARLIER AND PROBABLY BETTER POTENTIAL FOR LIGHT ICING THAN
ORIGINALLY FORECAST...AS TEMPS ACROSS NORTH CENTRAL IL ARE ALREADY
32-33F. SO HAVE EXPANDED FREEZING RAIN DEPICTION IN THE GRIDS AND
AGAIN STARTED THE ADVISORY EARLIER.
SATURDAY/SUNDAY...
HAVE MADE ADJUSTMENTS TO THE FORECAST GRIDS FOR SATURDAY INTO SUNDAY
BASED ON MODEL THERMAL PROFILES AND SOUNDINGS...PARTICULARLY THE
1000-850 MB CRITICAL THICKNESS (1300 DM) WHICH IS A KEY INDICATOR
FOR SNOW VERSUS RAIN/ZR/SLEET. THE GFS RUNS TODAY WERE THE COLDEST
WITH THE NAM/ECMWF SHOWING A MUCH MORE DISTINCT WARM NOSE AT 850
MB...BUT EVEN THE GFS WOULD ONLY FAVOR THE FAR NORTHERN CWA FOR A
WINTRY MIX TRANSITIONING TO SNOW/SLEET AND THEN ALL SNOW ON SATURDAY
NIGHT WHERE THERE IS THE BEST OVERLAP WITH FORCING AND LIFT THROUGH
THE DGZ. IN BETWEEN THE FAVORED AREA FOR MORE SIGNIFICANT SNOW/SLEET
ACCUMS AND MAINLY RAIN OVER THE SOUTHEAST HALF OF THE CWA...HAVE
INDICATED A TRANSITION ZONE WHERE A MIXED BAG INCLUDING FREEZING
RAIN IS POSSIBLE. AM CONCERNED THAT IF P-TYPE IS MAINLY ZR FOR A
TIME...THERE COULD BE DECENT ICE ACCRETION...AND THIS WOULD
INCLUDE PARTS OF THE WEST AND NORTHWEST CHICAGO METRO.
FINALLY...SUNDAY MORNING IT APPEARS THAT ALL BUT THE SOUTHEAST
THIRD OF THE CWA WILL TRANSITION OVER TO ALL SNOW AS COLDER AIR
PUSHES IN ALOFT.
THE TWEAKS TO QPF AND WEATHER TYPES AND SNOW AMOUNT GRIDS RESULTED
IN A MUCH TIGHTER SNOWFALL GRADIENT...WITH POTENTIAL FOR AMOUNTS IN
EXCESS OF 6 INCHES IN NORTH CENTRAL/NW AND EXTREME NORTHEASTERN
ILLINOIS...QUICKLY TAPERING TO THE SOUTHEAST. LITTLE OR NO SNOW
ACCUMULATION IS ANTICIPATED IN THE SOUTHEAST THIRD OF THE CWA.
NEEDLESS TO SAY...THIS IS STILL A FLUID SITUATION AND SMALL CHANGES
IN THE TRACK OF THE LOW PRESSURE SYSTEM AND THERMAL PROFILES WILL
HAVE LARGE IMPLICATIONS IN PRECIPITATION TYPE AND AMOUNTS. HAVE MADE
NO CHANGES TO THE WINTER STORM WATCH AND FLOOD WATCH IN EFFECT.
MTF/RC/RATZER
//PREV DISCUSSION...
UPDATED...415 PM CST FOR THIS WEEKEND PORTION
TONIGHT THROUGH FRIDAY NIGHT
UPDATED...1224 PM CST
FRONTAL BOUNDARY IS DRAPED FROM THE CHICAGO METRO AREA WSW TO NEAR
THE QUAD CITIES THIS AFTERNOON. ASCENT IS FORECAST TO INCREASE THIS
EVENING AND TONIGHT ON TOP OF THE BOUNDARY WHICH WILL MEANDER SOME
AS THE SURFACE WAVE LIFTS ACROSS THE REGION. WARM ADVECTION ALOFT
LEAVES LITTLE DOUBT THAT PRECIP WILL MELT ALOFT WITH 3-4C SATURATED
WARM LAYER TEMPS AS FAR NORTH AS THE WI STATE LINE. THE BIG CONCERN
WILL BE SURFACE/GROUND TEMPERATURE TRENDS. TEMPERATURES ARE
EXPECTED TO MOSTLY HOLD STEADY INTO THE LATE EVENING...THEN COLDER
//BELOW FREEZING// SURFACE TEMPS WILL START TO TRICKLE SOUTHEAST
INTO FAR NORTHERN IL AS THE LOW STARTS TO PASS TO OUR SOUTH.
CURRENTLY IT APPEARS THAT ONLY THE FAR REACHES OF THE CWA...
INCLUDING PORTIONS OF OGLE...WINNEBAGO...BOONE...AND MCHENRY
COUNTIES...WILL SEE SURFACE TEMPERATURES FALLING BELOW FREEZING
OVERNIGHT AND WHERE THE CONCERN FOR LIGHT FREEZING RAIN AND LIGHT
ICE ACCUMULATIONS WILL BE. A FREEZING RAIN ADVISORY HAS BEEN ISSUED
FOR THESE COUNTIES...AND EXPECT A GLAZE UP TO A TENTH OF AN INCH OF
ICE FOR THESE AREAS.
BY MID MORNING FRIDAY...TEMPERATURES ARE EXPECTED TO CONTINUE TO
SLOWLY FALL WITH THE LOW DEPARTING EAST. FORCING QUICKLY TAPERS BUT
PERSISTENT LOW LEVEL MOISTURE AND WEAK OMEGA RAISES THE CONCERN FOR
FREEZING DRIZZLE TO SPREAD SOUTH OF THE CURRENT ADVISORY
AREA...PERHAPS AS FAR SOUTH AS THE I-80 CORRIDOR. MID/HIGH LEVEL
MOISTURE WILL BE PRESENT...HOWEVER MID LEVEL DRY LAYER IS EXPECTED
TO INHIBIT SEEDER/FEEDER FROM INTRODUCING ICE INTO THE LOW LEVEL
MOISTURE LAYER...WHICH ONLY HAS TEMPERATURES AS COOL AS -5C.
SURFACE TEMPERATURES WILL BE RIGHT AROUND THE FREEZING MARK. FOR
NOW PLAN ON HIGHLIGHTING AREA WITH AN SPS...AND CANNOT RULE OUT
EXPANSION OF ADVISORY FARTHER SOUTH LATER INTO THE DAY FRIDAY IF
IT APPEARS TEMPERATURES WILL BE COOLER OR IF PRECIP MORE ROBUST.
DEUBELBEISS
FOR THE WEEKEND...
UPDATED...415 PM CST...
A VERY ACTIVE WEATHER PATTERN IS SETTING UP...WITH A FLOOD WATCH
ISSUED FOR THE SOUTHEASTERN PORTIONS OF THE CWA AND A WINTER STORM
WATCH ISSUED FOR THE NORTHERN AND NORTHWESTERN PORTIONS OF THE
CWA.
THE FIRST AREA OF CONCERN WILL BE THE POTENTIAL FOR HEAVY RAINFALL
OVER AT LEAST PORTIONS OF THE AREA. HAVE BEEN MONITORING THE
DEVELOPMENT OF A SOUTHERN STREAM SYSTEM OVER THE SOUTH HIGH PLAINS.
AS OF THURSDAY AFTERNOON...THE SYSTEM IS MOVING ONSHORE INTO
SOUTHERN CALIFORNIA AND WILL FINALLY BE SAMPLED BY THE UPPER AIR
DATA NETWORK. WHILE THE MODELS HAVE PROVIDED A MYRIAD OF SOLUTIONS
FOR THE TRACK OF THIS SYSTEM...MUCH OF THE VIABLE GUIDANCE LOOKED AT
TODAY IS CONVERGING ON THE "WARMER" SOLUTION FOR THE LOCAL
AREA...WITH THE EXCEPTION OF THE GFS WHICH IS THE OUTLIER...PUSHING
THE SYSTEM TO FAR EAST...TOO FAST. THE CONVERGED SOLUTION WILL
TRACK A SERIES OF WAVES ALONG A WARM FRONT DEVELOPING FROM THE SOUTH
HIGH PLAINS INTO NORTHERN ILLINOIS. WARM AIR...MOIST AIR...WITH
TEMPS IN THE UPPER 30S AND DEW POINTS IN THE LOWER TO MIDDLE 30S HAS
ALREADY OVERSPREAD MUCH OF THE AREA. THE WARM FRONT WILL MEANDER
OVER THE AREA AS THE MAIN SFC LOW DEEPENS AND TRACKS ALONG THE
BOUNDARY...CROSSING THE MIDDLE MISSISSIPPI VALLEY BY FRIDAY
MORNING. BY FRIDAY MORNING...THE WARM FRONT SHOULD LAY RIGHT
THROUGH THE MIDDLE OF THE CWA...WITH TEMPS IN THE LOWER 30S ALONG
THE WISCONSIN BORDER...WITH LOWER 40S OVER LOCATIONS SOUTH OF THE
ILLINOIS AND KANKAKEE RIVERS. AS THE SFC LOW TRACKS NEWD ALONG THE
PATH OF THE FRONTAL TROUGH...HIGH PRESSURE WILL BE MOVING OFF THE
SERN COAST. THIS WILL SET UP A WIDE OPEN GULF OF MEXICO...WITH
COPIOUS AMOUNTS OF MOISTURE STREAMING NWD. PWATS ARE FORECAST TO
RISE TO 1.0 TO 1.5 INCHES OVER THE SERN PORTIONS OF THE CWA RIDING
ON A STRONG LOW LEVEL JET...WITH MAX 850MB WINDS OVER 60-70KT.
WHILE THE STRONGEST OF THE LOW LEVEL JET WILL BE TO THE
SOUTH...MOSTLY OVER THE OHIO VALLEY...THERE WILL BE AMPLE ISENTROPIC
LIFT AND MOISTURE TRANSPORT TO SUPPORT AREAS OF HEAVY RAINFALL. AT
THIS POINT...IT LOOKS LIKE THE HEAVIEST RAIN WILL BE OVER THE SERN
PORTIONS OF THE CWA...OUTLINED IN THE FLOOD WATCH ISSUED THIS
AFTERNOON. HOWEVER...THE HEAVY RAIN WILL NOT BE THE ONLY PROBLEM.
WITH COOLER AIR REMAINING AT THE SFC NORTH OF THE WARM FRONT...THE
STRONG ISENTROPIC LIFT ALONG AND NORTH OF THE BOUNDARY WILL FORCE
THE WARMER AIR OVER THE COOLER AIR AT THE SFC...SETTING UP A PERIOD
OF MIXED FREEZING AND FROZEN PCPN. THE EXACT LOCATION OF THE WINTRY
MIX OF PCPN STILL REMAINS A LITTLE TOUGH TO NARROW DOWN...BUT MOST
OF THE AREA NORTH OF THE KANKAKEE AND ILLINOIS RIVERS WILL SEE A
LEAST SOME PERIODS OF THE WINTRY MIX PCPN...WITH THE ROCKFORD AREA
LIKELY NOT SEEING ANY LIQUID WHILE THE CHICAGO METRO SHOULD SEE SOME
AND AND SOME OF THE WINTRY MIX.
AS THE HEAVY RAIN SITUATION IS WINDING DOWN SATURDAY NIGHT OR EARLY
SUNDAY MORNING...THE MAIN FORECAST CONCERN WILL SHIFT TO THE
POTENTIAL FOR HEAVY SNOWFALL. THE SRN STREAM SYSTEM NOT ONLY WILL
BE RESPONSIBLE FOR DRAWING MOISTURE NORTHWARD...THERE SHOULD BE SOME
PHASING WITH A NORTHERN STREAM SHORTWAVE DROPPING OUT OF THE NRN
PLAINS. THIS SHOULD LEAD TO THE DEVELOPMENT OF A WEAK SECONDARY
CIRCULATION OVER NRN IL BY SUNDAY MORNING...ENHANCING THE DRAW OF
COOLER AIR FROM THE NORTH. THE STRONGER COLD ADVECTION AND A STRONG
DEFORMATION ZONE ARE ADVERTISED TO SET UP OVER NRN IL/SRN WI WHICH
WILL BE THE PRIMARY FOCUSING ELEMENTS FOR A BAND OF HEAVY SNOW. AT
THIS POINT...BASED ON THE GOOD CONSENSUS OF THE NAM AND
ECMWF...WHICH WOULD WOULD INDICATE AN AXIS OF HEAVIER SNOW GENERALLY
FROM ERN IOWA TO SERN WISCONSIN. ALL THINGS CONSIDERED...CONFIDENCE
IS BECOMING HIGH ENOUGH FOR IN EXCESS OF 6 INCHES OF SNOW OVER THE
NRN AND NWRN PORTIONS OF THE CWA...AS OUTLINED IN THE WINTER STORM
WATCH ISSUED THIS AFTERNOON. CURRENTLY ANTICIPATE THAT THE ENTIRE
CWA WILL SEE AT LEAST SOME SNOW...WITH 2 TO 4 INCHES ALONG A LINE
FROM CHICAGO TO PONTIAC AND 1 TO 2 INCHES FROM VALPARAISO TO
PONTIAC...TAPERING OFF TO AN INCH OR LESS OVER THE FAR SERN PORTIONS
OF THE CWA.
AK
LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...
UPDATED 316 PM CST
SUNDAY NIGHT...
GUIDANCE CONTINUES TO BE CONSISTENT IN DELIVERING A SHOT OF ARCTIC
AIR IN THE WAKE OF THE SIGNIFICANT WEEKEND STORM. A NORTHERN STREAM
TROUGH CURRENTLY NEAR THE NORTH POLE WILL DIG IN OVER THE NORTH
CENTRAL CONUS COUPLED WITH A ~1040 MB HIGH DROPPING SOUTH FROM THE
NORTHERN PLAINS. ALL OF THE SYSTEM SNOWS SHOULD BE OFF TO THE EAST
SUNDAY NIGHT...BUT POSITIVE VORTICITY ADVECTION FROM SHORT WAVES
ROTATING AROUND DEEP UPPER TROUGH COULD SQUEEZE OUT SOME LIGHT SNOW
OR FLURRIES IN THE ARCTIC AIR MASS. THE ECMWF CONTINUES TO BE MOST
BULLISH IN SQUEEZING OUT LIGHT QPF OVER THE AREA. THERE ALSO COULD
BE A BRIEF PERIOD OF FAVORABLE LAKE EFFECT CONDITIONS FOR PORTIONS
OF NW INDIANA DEPENDING ON IF WINDS CAN REMAIN CLOSER TO DUE NORTH
BEFORE BACKING WEST NORTHWEST. TEMPERATURES WILL PLUMMET IN STRONG
COLD ADVECTION BUT PERSISTENT NW WINDS AND CLOUD COVER COULD LIMIT
HOW FAR THEY FALL. WITH THE RAPIDLY FALLING TEMPERATURES SUNDAY
NIGHT...THERE COULD VERY WELL BE A FLASH FREEZE OF ANY REMAINING
MOISTURE ON THE GROUND.
MONDAY...
MAINTAINED A SLIGHT CHANCE OF FLURRIES ON MONDAY MORNING AS THE DEEP
UPPER TROUGH WILL BE OVERHEAD AND IT MAY NOT BE HARD TO SQUEEZE OUT
DENDRITES DESPITE THE COLD DRY AIR MASS. ALSO GUIDANCE INDICATES A
FAIRLY STOUT WAVE FOCUSED INTO THE NORTHEAST CWA AND WISCONSIN...SO
FELT COMFORTABLE WITH THE SLIGHT CHANCE POP FROM GUIDANCE BLEND
INITIALIZATION FOR NORTHEAST IL AND EXTREME NW INDIANA. HIGH
TEMPERATURES MONDAY AND LOWS MONDAY NIGHT WILL BE COLD
EVERYWHERE...BUT HOW COLD WILL DEPEND ON WHICH AREAS MAINTAIN
SUBSTANTIAL SNOW PACK AFTER THE WEEKEND SYSTEM. AT THIS TIME...IT
APPEARS THAT THE NORTHERN CWA WOULD HAVE THE BEST CHANCE. WITH
SURFACE HIGH BEING NEAR OR OVER THE AREA AND NO MORE THAN PARTLY
CLOUDY SKIES EXPECTED...DROPPED LOW TEMPERATURES MONDAY NIGHT FROM
PREVIOUS FORECAST TO 5 TO 10 BELOW WEST OF THE FOX VALLEY. STAYED
MORE CONSERVATIVE IN THE SOUTHERN CWA WHERE LITTLE OR NO SNOW COVER
SHOULD BE LEFT. TO NOTE...THE ECMWF AND GFS WHICH HAVE CLEAR SKIES
HAVE LOWS IN THE COLDEST SPOTS 10 DEGREES COLDER THAN IN FORECAST
GRIDS...WHILE CANADIAN MODEL KEEPS CLOUD COVER AND IS A GOOD DEAL
WARMER.
TUESDAY NIGHT THROUGH THURSDAY...
AFTER A BITTERLY COLD START TO CHRISTMAS EVE DAY...SOUTHWEST WARM
ADVECTION BEHIND TROUGH DEPARTING TO THE EAST WILL ENABLE A DECENT
AFTERNOON TEMPERATURE RECOVERY...BUT STILL WELL BELOW CLIMO. COULD
SEE TEMPERATURES BEING A BIT WARMER THAN CURRENTLY FORECAST IN AREAS
WITHOUT SNOW COVER. WILL HAVE TO WATCH FOR A NORTHERN STREAM WAVE
BEING A BIT FARTHER SOUTH THAN MODEL CONSENSUS ON CHRISTMAS EVE
NIGHT...BUT WITH ECMWF TRENDING SOUTH...INDICATED A SLIGHT CHANCE OF
LIGHT SNOW NEAR THE WISCONSIN BORDER. THIS FEATURE COULD THEN GO ON
TO RESULT IN AT LEAST SOME LIGHT SNOW OR FLURRIES IN THE AIR FOR THE
ENTIRE AREA ON CHRISTMAS DAY. THIS WOULD BE A CONSOLATION PRIZE FOR
AREAS THAT LOSE THEIR SNOW COVER THIS WEEKEND...BUT FOR AREAS THAT
KEEP AT LEAST 1 INCH OF SNOW ON THE GROUND...A WHITE CHRISTMAS IS
HIGHLY LIKELY. TEMPERATURES WILL MODERATE TO NEAR NORMAL ON
CHRISTMAS DAY...WITH ANOTHER SHOT OF ARCTIC AIR POSSIBLE ON THURSDAY
BEHIND THE CHRISTMAS DAY SYSTEM.
CONFIDENCE IN A WHITE CHRISTMAS FOR AREAS THAT MAINTAIN AT LEAST 1
INCH OF SNOW COVER THIS WEEKEND...HIGH.
RC
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 06Z...
* VSBY AROUND 1SM WITH CIGS 002-004 THROUGH THE NIGHT WITH MINIMAL
IMPROVEMENT EXPECTED AFTER DAYBREAK.
* PERIODIC -SHRA/-DZ THROUGH MIDDAY FRIDAY WITH DECREASING CHANCES
THROUGH THE AFTERNOON. LOW CHANCE FOR SOME -FZRA/FZDZ FRIDAY
AFTERNOON.
* NORTH-NORTHEAST WINDS PERSIST THROUGH THE AFTERNOON WITH SPEEDS
INCREASING TO NEAR 10 KT BY MIDDAY.
* WINDS SHIFT NORTH-NORTHWEST FRIDAY EVENING WITH SOME CIG/VSBY
IMPROVEMENT POSSIBLE.
MDB
//DISCUSSION...UPDATED 06Z...
MESSY CONDITIONS CONTINUE ACROSS THE TERMINALS TONIGHT WITH A
FRONTAL BOUNDARY STRETCHING FROM LOW PRESSURE OVER OKLAHOMA TO
ROUGHLY A KEOK TO KC75 TO KVPZ LINE. ABUNDANT MOISTURE AND LIFT
CONTINUE OVER THE BOUNDARY BRINGING RAIN SHOWERS AND AREAS OF
DRIZZLE TO THE TERMINALS. VSBY IS LOWEST RIGHT ALONG THE BOUNDARY
WITH GYY AROUND 1/4SM AND THIS WILL LIKELY PERSIST AS LONG AS THE
BOUNDARY IS NEARBY...WHICH AT THIS POINT LOOKS TO BE FOR MUCH OF
THE OVERNIGHT. AREAS NORTH HAVE SEEN VSBY GENERALLY AROUND A MILE
AND THIS SHOULD BE THE TREND THROUGH THE NIGHT...THOUGH THERE MAY
BE SOME DOWNWARD FLUCTUATIONS AT TIMES. CIGS SHOULD STAY STEADY
IN THE 002-004 RANGE THROUGH THE NIGHT AS WELL. RFD MAY SEE SOME
FREEZING RAIN/FREEZING DRIZZLE OVERNIGHT AS TEMPS COOL SLIGHTLY.
THINGS BECOME LESS CERTAIN AFTER DAYBREAK. THE LOW WILL TRACK
NORTHEAST TO NORTH-CENTRAL INDIANA BY FRIDAY AFTERNOON TURNING
WINDS FROM NORTHEAST TO NORTH-NORTHWEST THROUGH THE AFTERNOON. THE
MAIN QUESTION WILL BE HOW QUICKLY AND TO WHAT EXTENT CIGS/VSBY
IMPROVE. WITH THE BOUNDARY STILL IN THE AREA THROUGH THE MORNING
WILL ONLY HAVE VERY MINOR INCREASES IN CIGS/VSBY WITH BETTER
INCREASES DURING THE AFTERNOON AS COLDER AIR FILTERS INTO THE
REGION. SHOWERS/DRIZZLE WILL CONTINUE PERIODICALLY BEFORE TAPERING
OFF DURING THE AFTERNOON. RFD WILL HAVE THE BEST CHANCE OF SEEING
FREEZING RAIN THROUGH THE MORNING...WITH A LOW CHANCE THAT SOME
LIGHT FREEZING RAIN OR FREEZING DRIZZLE WILL MAKE IT INTO THE
CHICAGO TERMINALS DURING THE EARLY AFTERNOON AS COLDER AIR
ARRIVES. MVFR AND POSSIBLY IFR LOOK TO BE IN PLACE FOR FRIDAY
EVENING WITH NORTH-NORTHWEST WINDS.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 06Z...
* HIGH CONFIDENCE VSBY AROUND 1SM AND CIGS 002-004 THROUGH THE
OVERNIGHT. LOW CONFIDENCE IN DEGREE OF ANY VARIABILITY AND
TIMING/MAGNITUDE OF IMPROVEMENT AFTER DAYBREAK.
* HIGH CONFIDENCE IN PERIODIC -SHRA/-DZ THROUGH MIDDAY
FRIDAY...WITH LOW CONFIDENCE IN -FZRA/-FZDA EARLY FRIDAY
AFTERNOON.
* HIGH CONFIDENCE IN WIND TRENDS.
MDB
//OUTLOOK FOR ORD/MDW FOR 12Z SATURDAY-12Z THURSDAY...UPDATED 00Z...
SAT...WINTRY MIX OF PRECIP FROM MIDDAY ON...WITH A CHANCE OF A
PERIOD OF FREEZING RAIN DURING THE NIGHT. MVFR TO IFR.
SUN...SNOW. MVFR TO IFR.
MON...MVFR CIGS. CHANCE OF SNOW SHOWERS WITH IFR.
TUE...VFR.
WED...VFR BECOMING MVFR CIGS.
THU...MVFR CIGS IMPROVING TO VFR.
TRS
&&
.MARINE...
308 PM CST
THERE ARE TWO LOWS SET TO MOVE FROM THE SOUTHERN PLAINS TO THE
LOWER/EASTERN GREAT LAKES REGION THROUGH SUNDAY. THE SECOND ONE WILL
HAVE A LARGER INFLUENCE ON THE WINDS ACROSS THE LAKE...NAMELY
SATURDAY NIGHT THROUGH EARLY MONDAY. AS WINDS TURN
NORTHERLY BEHIND THIS LOW...SPEEDS WILL INCREASE BUT ARE LIKELY TO
REMAIN BELOW GALES ON SUNDAY...ALTHOUGH COULD BE CLOSE ESPECIALLY
IF THE SYSTEM IS DEEPER THAN FORECAST.
IN THE IMMEDIATE NEAR TERM...A FRONT WILL REMAIN DRAPED ACROSS THE
SOUTHERN TWO TO FOUR OPEN WATER ZONES OF LAKE MICHIGAN...WHERE
WINDS WILL BE SOMEWHAT VARIABLE IN SPEED. THIS FRONT WILL INCH
SOUTHWARD FRIDAY MORNING IN THE WAKE OF THE FIRST LOW.
A WINTRY MIX IS EXPECTED ACROSS THE SOUTHERN TWO-THIRDS OF THE
LAKE WITH BOTH SYSTEMS...TONIGHT AND FRIDAY AND AGAIN SATURDAY
NIGHT WHICH SHOULD CHANGE TO ALL SNOW SUNDAY.
IN THE WAKE OF THESE SYSTEMS...STRONG HIGH PRESSURE WILL PASS TO
THE SOUTH OF THE REGION BEFORE LIKELY STRONG SOUTHERLY WINDS TAKE
EFFECT ACROSS THE ENTIRE LAKE SOMETIME CHRISTMAS EVE NIGHT INTO
CHRISTMAS.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...FREEZING RAIN ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-
ILZ010-ILZ011 UNTIL NOON FRIDAY.
WINTER STORM WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012...6 PM SATURDAY TO 6 PM SUNDAY.
FLOOD WATCH...ILZ033-ILZ039...9 AM SATURDAY TO 6 AM SUNDAY.
IN...DENSE FOG ADVISORY...INZ001-INZ002 UNTIL 9 AM FRIDAY.
FLOOD WATCH...INZ010-INZ011-INZ019...9 AM SATURDAY TO 6 AM
SUNDAY.
LM...SMALL CRAFT ADVISORY...LMZ740...9 AM FRIDAY TO 9 PM FRIDAY.
DENSE FOG ADVISORY...INDIANA NEARSHORE WATERS UNTIL 9 AM FRIDAY.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
320 AM EST FRI DEC 20 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 245 AM EST FRI DEC 20 2013
AN ACTIVE...WET...WEATHER PATTERN WILL BE IN PLACE FOR CENTRAL
INDIANA FOR THE NEXT COUPLE OF DAYS...BRINGING ABUNDANT RAINFALL.
A FRONTAL BOUNDARY IS EXPECTED TO PUSH ACROSS INDIANA VERY SLOWLY
OVER THE NEXT FEW DAYS. AS THE FRONT SLOWLY PASSES TO THE
SOUTHEAST THROUGH SUNDAY SEVERAL UPPER LEVEL DISTURBANCES ARE
EXPECTED TO PUSH ALONG THE FRONT...RESULTING IN RAIN. VERY WARM AND
MOIST AIR AHEAD OF THE FRONT WILL PROVIDE AMPLE MOISTURE FOR
WIDESPREAD RAINFALL...SOME OF WHICH COULD BE HEAVY AND RESULT IN
FLOODING.
COLD HIGH PRESSURE WILL BUILD INTO THE REGION TO START NEXT WEEK.
A WEAK LOW PRESSURE TROUGH WILL MOVE INTO THE GREAT LAKES AND OHIO
VALLEY NEXT THURSDAY AND MAY PRODUCE SOME LIGHT SNOW.
&&
.NEAR TERM /TODAY/...
ISSUED AT 245 AM EST FRI DEC 20 2013
SURFACE ANALYSIS EARLY THIS MORNING SHOWS LOW PRESSURE OVER
MISSOURI WITH A WARM FRONT EXTENDING NORTHEAST INTO NORTHERN
ILLINOIS AND SOUTHERN MICHIGAN. ABUNDANT CLOUD COVER WAS STREAMING
NORTHWARD INTO THE OHIO VALLEY AHEAD OF THE FRONT. WATER VAPOR
IMAGERY SHOWS A DEEPENING TROUGH OVER THE AMERICAN
SOUTHWEST...WITH A STREAM OF TROPICAL MOISTURE STRETCHING ACROSS
TEXAS INTO THE OHIO VALLEY. RADAR SHOWS SCATTERED SHOWERS DEVELOPING ACROSS
INDIANA AND NORTHERN ILLINOIS. DEW POINTS WERE IN THE MIDDLE 40S
AS SURFACE FLOW WAS FROM THE SOUTH ACROSS THE FORECAST AREA.
GFS AND NAM FAIL TO SHOW MUCH IN THE WAY OF ORGANIZED SHORT WAVES
PUSHING ACROSS THE FORECAST AREA TODAY. HOWEVER THE 300K GFS
ISENTROPIC SURFACE SHOWS GOOD LIFT STARTING TODAY WITH A SURGE OF
MOISTURE...SPECIFIC HUMIDITIES OVER 5 G/KG...PUSHING INTO THE
AREA THIS MORNING. FORECAST SOUNDINGS SHOW DEEP MOISTURE AVAILABLE
AROUND 12Z...WITH LOWER LEVEL MOISTURE LINGERING ACROSS THE AREA
THROUGH THE DAY. MODERATE LOWER LEVEL JET...NEAR 40 KNTS...IS
EXPECTED TO REMAIN IN THE AREA TODAY. GOOD LOWER LEVEL CONVERGENCE
IS SEEN IN THE Q VECTORS TODAY AS THE SURFACE FRONTAL BOUNDARY
SAGS EASTWARD ACROSS INDIANA ALONG WITH A WEAK LOW PRESSURE CENTER.
THUS WITH THESE FAVORABLE INGREDIENTS FOR PRECIP WILL TREND TOWARD
THE 100 POPS AS SEEN IN MUCH OF THE GUIDANCE. WITH THE EXPECTED
RAINFALL AMID THE STRONG WARM AIR ADVECTION...WILL TREND HIGHS AT OR
ABOVE GUIDANCE.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 245 AM EST FRI DEC 20 2013
A VERY ACTIVE AND VERY WET PATTERN LOOKS TO BE IN PLACE THROUGH
SUNDAY AFTERNOON. MAIN FORECAST CHALLENGE WILL BE POPS. THE STRONG
WAVE OVER THE AMERICAN SOUTHWEST IS EXPECTED TO PUSH QUICKLY TOWARD
THE OHIO VALLEY AMID THE SOUTHWEST FLOW ON FRIDAY NIGHT...AND
THEN PASS ACROSS INDIANA ON SATURDAY NIGHT. A VERY FAVORABLE SET UP
FOR RAIN REMAINS IN PLACE. AT THE SURFACE...A FRONTAL BOUNDARY
REMAINS IN PLACE ACROSS INDIANA. THIS RESULTS IN GOOD LOWER LEVEL Q
VECTOR CONVERGENCE. THE PREVIOUSLY MENTIONED TROPICAL FLOW ALOFT WILL
HELP PROVIDE AMPLE MOISTURE. PRECIPITABLE WATER TONIGHT THROUGH
SATURDAY NIGHT REMAINS OVER 1 INCH WHICH IS OVER 100 PERCENT OF
NORMAL. THIS SHOWS WE ARE DEALING WITH A VERY MOIST AIR MASS FOR
THIS TIME OF YEAR. FORECAST SOUNDINGS SHOW DEEP SATURATION
PERSISTING ACROSS THE AREA THROUGH AT LEAST SATURDAY NIGHT. NAM AND
GFS ALSO SHOW A VERY STRONG LOWER LEVEL JET NEAR 70 KNTS PUSHING
THROUGH THE OHIO VALLEY ON SATURDAY AND SATURDAY NIGHT. AGAIN...ALL
OF THESE THINGS ARE QUITE FAVORABLE FOR RAIN...AND SOME OF THE RAIN
SHOULD BE HEAVY. VERY IMPRESSED WITH NAM RAW OUTPUT SUGGESTING 17-20
UBAR/S OF LIFT ON SATURDAY AFTERNOON AND SATURDAY NIGHT. THAT SPITS
OUT OVER 2.5 INCHES OF RAIN IF IT VERIFIES. BOTTOM LINE HERE IS VERY
STRONG FORCING WILL BE PUSHING THROUGH. THE ONGOING FLOOD WATCH
LOOKS LIKE A GOOD BET. WOULD NOT BE SURPRISED TO SEE AREAL FLOOD
WARNINGS THIS WEEKEND. INTERESTING FACT FOR IND...IN DECEMBER THE
NORMAL AMOUNT OF PRECIPITATION FOR THE ENTIRE MONTH IS 3.17 INCHES.
WE COULD SEE 2/3RDS OR MORE OF THAT ON FRI NIGHT-SAT-SATURDAY NIGHT.
WILL USE 100 POPS. GIVEN THE CLOUDS AND PRECIP...WILL TREND HIGHS
COOLER THAN GUIDANCE AND LOWS WARMER.
THE STRONGEST FORCING DEPARTS THE AREA TO THE NORTHEAST ON SUNDAY
AS A DRY SLOT BEGINS TO INTRUDE FROM THE SOUTHWEST. FORECAST
SOUNDINGS SHOW SUBSIDENCE BUILDING ALOFT AS THEY BEGIN TO DRY
OUT...TOP DOWN. LOWER LEVELS REMAIN SATURATED...INDICATIVE OF
TRAPPED STRATOCU AMID COLD AIR ADVECTION. FORECAST SOUNDINGS BEGIN
TO TAKE A TUMBLE ON SUNDAY AFTERNOON ALSO...AS THE SURFACE COLD
FRONT PUSHES SOUTHEAST OF THE OHIO VALLEY. BY 00Z MONDAY...THE
MAJORITY OF THE FORECAST SOUNDINGS ARE BELOW FREEZING AND DEEP
MOISTURE IS LOST AS SURFACE HIGH PRESSURE OVER THE PLAINS STATES
PROVIDES A COLD NORTHWEST FLOW OF COLD AIR AS 850MB TEMPS FALL
BACK TO NEAR 0C. MOISTURE ON SUNDAY AND SUNDAY NIGHT APPEARS
LIMITED AS PRECIPITABLE WATER IS REDUCED TO MORE NORMAL LEVELS AND
DRY AIR CONTINUES TO STREAM INTO THE COLUMN. HOWEVER WITH
LINGERING LOWER LEVEL MOISTURE AND BROAD CYCLONIC FLOW IN PLACE ON
SUNDAY AND SUNDAY NIGHT...CANNOT RULE OUT LIGHT PRECIPITATION
AMOUNTS. WILL STICK CLOSE TO GUIDANCE POPS AT THOSE TIMES. GIVEN
THE CHANGE IN AIR MASS WILL TREND COOLER THAN THE MAVMOS ON SUNDAY
HIGHS AND PROBABLY COOLER THAN MEXMOS LOWS ON SUNDAY NIGHT GIVEN
THE EXPECTED COLD AIR ADVECTION.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
ISSUED AT 315 AM EST FRI DEC 20 2013
MODELS ARE IN GOOD AGREEMENT EARLY BUT VARY A DECENT BIT NEAR THE
END OF THE FORECAST PERIOD IN REGARDS TO TEMPERATURES. GENERALLY DID
NOT DEVIATE FROM ALLBLEND WITH EXCEPTIONS MENTIONED BELOW. THE LONG
TERM STARTS WITH CANADIAN HIGH PRESSURE BUILDING OVER THE AREA. THIS
WILL MOVE ACROSS CENTRAL INDIANA THROUGH TUESDAY NIGHT KEEPING DRY
WEATHER IN THE FORECAST AND BELOW NORMAL TEMPERATURES WITH HIGHS
MAINLY IN THE 20S. BY WEDNESDAY THE HIGH WILL BE OFF TO THE EAST
ALLOWING TEMPERATURES TO CLIMB INTO THE MID TO UPPER 30S. AFTER THAT
AN UPPER LOW WILL SWING THROUGH ONTARIO AND BRING A COLD FRONT
THROUGH INDIANA BETWEEN WEDNESDAY NIGHT AND THURSDAY ALONG WITH A
WEAK UPPER WAVE. THIS WILL BRING LOW CHANCES FOR SNOW TO THE AREA
AND A REINFORCING SHOT OF COLD AIR FOR THE END OF THE WEEK. TRENDED
TEMPERATURES LOWER THAN ALLBLEND ON THURSDAY TO LEAN CLOSER TO THE
COLDER TEMPERATURES OF THE ECMWF WHICH MATCH THE UPPER PATTERN
BETTER.
&&
.AVIATION /DISCUSSION FOR 200900Z TAF ISSUANCE/...
ISSUED AT 315 AM EST FRI DEC 20 2013
UPDATED TO IMPROVE CONDITIONS FOR THE NEXT FEW HOURS AS THEY ARE
FALLING SLOWER THAN ANTICIPATED. WITH THE FRONT TO THE NORTH OF
THE SITES MAY TAKE LONGER FOR POOR FLYING CONDITIONS TO DEVELOP. PREVIOUS
DISCUSSION FOLLOWS...
STEADILY DETERIORATING CONDITIONS FOR AVIATORS WITH LIFR
CONDITIONS DEVELOPING FOR MUCH OF FRIDAY.
FRONTAL BOUNDARY EXTENDING FROM SOUTHERN LOWER MICHIGAN W/SW INTO
NORTH CENTRAL ILLINOIS LATE THIS EVENING. STRENGTHENING LOW LEVEL
JET CONTINUES TO BRING GULF MOISTURE INTO THE OHIO VALLEY. RH
PROGS AT 950/925MB OFF THE RAP INDICATE SUBTLY DRIER AIR LIFTING
NORTH ACROSS CENTRAL INDIANA...AND THIS HAS LIKELY DELAYED
CEILINGS FROM FALLING BELOW VFR. AS DEEPER MOISTURE AND LIGHT RAIN
SHOWERS EXPAND INTO THE FORECAST AREA OVERNIGHT...EXPECT IFR
CEILINGS TO BECOME PREVALENT PRIOR TO DAYBREAK...DROPPING TO 500FT
OR LOWER AS THE INVERSION STRENGTHENS DURING THE MORNING.
RAIN WILL CONTINUE AS WELL THROUGH MUCH OF THE DAY AS A SURFACE
WAVE TRAVERSES THE NEARLY STATIONARY BOUNDARY JUST TO THE
NORTHWEST OF THE REGION. SLIGHTLY DRIER AIR ALOFT ATTEMPTS TO
BRIEFLY WORK INTO THE REGION BEHIND THE SURFACE WAVE LATE FRIDAY
AFTERNOON BUT WITH SATURATED CONDITIONS TRAPPED BENEATH THE
INVERSION...MAY ONLY SEE RAIN LIGHTEN TO DRIZZLE FOR A FEW HOURS.
MORE WIDESPREAD AND HEAVIER RAINFALL WILL QUICKLY EXPAND INTO
CENTRAL INDIANA NEAR THE END OF THE FORECAST PERIOD AS DEEPER
MOISTURE ADVECTS INTO THE OHIO VALLEY.
LOW LEVEL WIND SHEAR WILL REMAIN A FACTOR THROUGH THE FIRST 12
HOURS OF THE FORECAST WITH THE PRESENCE OF THE LOW LEVEL JET. RAP
INDICATING POTENTIAL FOR SOUTHWEST WINDS TO APPROACH 60KTS
OVERNIGHT IN THE 2-3KFT LAYER. LLWS CONCERNS WILL NOT DIMINISH
UNTIL EARLY AFTERNOON AS THE LOW LEVEL JET WEAKENS. SOUTHWEST
WINDS AT 10 TO 15 KTS ARE EXPECTED THROUGH MUCH OF THE PERIOD...
VEERING TO MORE OF A WESTERLY DIRECTION FRIDAY EVENING AS THE
BOUNDARY SAGS INTO THE FORECAST AREA.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR INZ021-
028>031-035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...PUMA
NEAR TERM...PUMA
SHORT TERM...PUMA
LONG TERM....CP
AVIATION...RYAN/CP
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
245 AM EST FRI DEC 20 2013
.UPDATE...
THE SYNOPSIS...NEAR TERM AND SHORT TERM SECTIONS HAVE BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 245 AM EST FRI DEC 20 2013
AN ACTIVE...WET...WEATHER PATTERN WILL BE IN PLACE FOR CENTRAL
INDIANA FOR THE NEXT COUPLE OF DAYS...BRINGING ABUNDANT RAINFALL.
A FRONTAL BOUNDARY IS EXPECTED TO PUSH ACROSS INDIANA VERY SLOWLY
OVER THE NEXT FEW DAYS. AS THE FRONT SLOWLY PASSES TO THE
SOUTHEAST THROUGH SUNDAY SEVERAL UPPER LEVEL DISTURBANCES ARE
EXPECTED TO PUSH ALONG THE FRONT...RESULTING IN RAIN. VERY WARM AND
MOIST AIR AHEAD OF THE FRONT WILL PROVIDE AMPLE MOISTURE FOR
WIDESPREAD RAINFALL...SOME OF WHICH COULD BE HEAVY AND RESULT IN
FLOODING.
COLD HIGH PRESSURE WILL BUILD INTO THE REGION TO START NEXT WEEK.
A WEAK LOW PRESSURE TROUGH WILL MOVE INTO THE GREAT LAKES AND OHIO
VALLEY NEXT THURSDAY AND MAY PRODUCE SOME LIGHT SNOW.
&&
.NEAR TERM /TODAY/...
ISSUED AT 245 AM EST FRI DEC 20 2013
SURFACE ANALYSIS EARLY THIS MORNING SHOWS LOW PRESSURE OVER
MISSOURI WITH A WARM FRONT EXTENDING NORTHEAST INTO NORTHERN
ILLINOIS AND SOUTHERN MICHIGAN. ABUNDANT CLOUD COVER WAS STREAMING
NORTHWARD INTO THE OHIO VALLEY AHEAD OF THE FRONT. WATER VAPOR
IMAGERY SHOWS A DEEPENING TROUGH OVER THE AMERICAN
SOUTHWEST...WITH A STREAM OF TROPICAL MOISTURE STRETCHING ACROSS
TEXAS INTO THE OHIO VALLEY. RADAR SHOWS SCATTERED SHOWERS DEVELOPING ACROSS
INDIANA AND NORTHERN ILLINOIS. DEW POINTS WERE IN THE MIDDLE 40S
AS SURFACE FLOW WAS FROM THE SOUTH ACROSS THE FORECAST AREA.
GFS AND NAM FAIL TO SHOW MUCH IN THE WAY OF ORGANIZED SHORT WAVES
PUSHING ACROSS THE FORECAST AREA TODAY. HOWEVER THE 300K GFS
ISENTROPIC SURFACE SHOWS GOOD LIFT STARTING TODAY WITH A SURGE OF
MOISTURE...SPECIFIC HUMIDITIES OVER 5 G/KG...PUSHING INTO THE
AREA THIS MORNING. FORECAST SOUNDINGS SHOW DEEP MOISTURE AVAILABLE
AROUND 12Z...WITH LOWER LEVEL MOISTURE LINGERING ACROSS THE AREA
THROUGH THE DAY. MODERATE LOWER LEVEL JET...NEAR 40 KNTS...IS
EXPECTED TO REMAIN IN THE AREA TODAY. GOOD LOWER LEVEL CONVERGENCE
IS SEEN IN THE Q VECTORS TODAY AS THE SURFACE FRONTAL BOUNDARY
SAGS EASTWARD ACROSS INDIANA ALONG WITH A WEAK LOW PRESSURE CENTER.
THUS WITH THESE FAVORABLE INGREDIENTS FOR PRECIP WILL TREND TOWARD
THE 100 POPS AS SEEN IN MUCH OF THE GUIDANCE. WITH THE EXPECTED
RAINFALL AMID THE STRONG WARM AIR ADVECTION...WILL TREND HIGHS AT OR
ABOVE GUIDANCE.
&&
.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
ISSUED AT 245 AM EST FRI DEC 20 2013
A VERY ACTIVE AND VERY WET PATTERN LOOKS TO BE IN PLACE THROUGH
SUNDAY AFTERNOON. MAIN FORECAST CHALLENGE WILL BE POPS. THE STRONG
WAVE OVER THE AMERICAN SOUTHWEST IS EXPECTED TO PUSH QUICKLY TOWARD
THE OHIO VALLEY AMID THE SOUTHWEST FLOW ON FRIDAY NIGHT...AND
THEN PASS ACROSS INDIANA ON SATURDAY NIGHT. A VERY FAVORABLE SET UP
FOR RAIN REMAINS IN PLACE. AT THE SURFACE...A FRONTAL BOUNDARY
REMAINS IN PLACE ACROSS INDIANA. THIS RESULTS IN GOOD LOWER LEVEL Q
VECTOR CONVERGENCE. THE PREVIOUSLY MENTIONED TROPICAL FLOW ALOFT WILL
HELP PROVIDE AMPLE MOISTURE. PRECIPITABLE WATER TONIGHT THROUGH
SATURDAY NIGHT REMAINS OVER 1 INCH WHICH IS OVER 100 PERCENT OF
NORMAL. THIS SHOWS WE ARE DEALING WITH A VERY MOIST AIR MASS FOR
THIS TIME OF YEAR. FORECAST SOUNDINGS SHOW DEEP SATURATION
PERSISTING ACROSS THE AREA THROUGH AT LEAST SATURDAY NIGHT. NAM AND
GFS ALSO SHOW A VERY STRONG LOWER LEVEL JET NEAR 70 KNTS PUSHING
THROUGH THE OHIO VALLEY ON SATURDAY AND SATURDAY NIGHT. AGAIN...ALL
OF THESE THINGS ARE QUITE FAVORABLE FOR RAIN...AND SOME OF THE RAIN
SHOULD BE HEAVY. VERY IMPRESSED WITH NAM RAW OUTPUT SUGGESTING 17-20
UBAR/S OF LIFT ON SATURDAY AFTERNOON AND SATURDAY NIGHT. THAT SPITS
OUT OVER 2.5 INCHES OF RAIN IF IT VERIFIES. BOTTOM LINE HERE IS VERY
STRONG FORCING WILL BE PUSHING THROUGH. THE ONGOING FLOOD WATCH
LOOKS LIKE A GOOD BET. WOULD NOT BE SURPRISED TO SEE AREAL FLOOD
WARNINGS THIS WEEKEND. INTERESTING FACT FOR IND...IN DECEMBER THE
NORMAL AMOUNT OF PRECIPITATION FOR THE ENTIRE MONTH IS 3.17 INCHES.
WE COULD SEE 2/3RDS OR MORE OF THAT ON FRI NIGHT-SAT-SATURDAY NIGHT.
WILL USE 100 POPS. GIVEN THE CLOUDS AND PRECIP...WILL TREND HIGHS
COOLER THAN GUIDANCE AND LOWS WARMER.
THE STRONGEST FORCING DEPARTS THE AREA TO THE NORTHEAST ON SUNDAY
AS A DRY SLOT BEGINS TO INTRUDE FROM THE SOUTHWEST. FORECAST
SOUNDINGS SHOW SUBSIDENCE BUILDING ALOFT AS THEY BEGIN TO DRY
OUT...TOP DOWN. LOWER LEVELS REMAIN SATURATED...INDICATIVE OF
TRAPPED STRATOCU AMID COLD AIR ADVECTION. FORECAST SOUNDINGS BEGIN
TO TAKE A TUMBLE ON SUNDAY AFTERNOON ALSO...AS THE SURFACE COLD
FRONT PUSHES SOUTHEAST OF THE OHIO VALLEY. BY 00Z MONDAY...THE
MAJORITY OF THE FORECAST SOUNDINGS ARE BELOW FREEZING AND DEEP
MOISTURE IS LOST AS SURFACE HIGH PRESSURE OVER THE PLAINS STATES
PROVIDES A COLD NORTHWEST FLOW OF COLD AIR AS 850MB TEMPS FALL
BACK TO NEAR 0C. MOISTURE ON SUNDAY AND SUNDAY NIGHT APPEARS
LIMITED AS PRECIPITABLE WATER IS REDUCED TO MORE NORMAL LEVELS AND
DRY AIR CONTINUES TO STREAM INTO THE COLUMN. HOWEVER WITH
LINGERING LOWER LEVEL MOISTURE AND BROAD CYCLONIC FLOW IN PLACE ON
SUNDAY AND SUNDAY NIGHT...CANNOT RULE OUT LIGHT PRECIPITATION
AMOUNTS. WILL STICK CLOSE TO GUIDANCE POPS AT THOSE TIMES. GIVEN
THE CHANGE IN AIR MASS WILL TREND COOLER THAN THE MAVMOS ON SUNDAY
HIGHS AND PROBABLY COOLER THAN MEXMOS LOWS ON SUNDAY NIGHT GIVEN
THE EXPECTED COLD AIR ADVECTION.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
ISSUED AT 205 PM EST THU DEC 19 2013
LONG TERM PERIOD WILL GENERALLY BE A QUIET ONE WITH STRONG HIGH
PRESSURE TRAVERSING THE REGION IN BETWEEN THE VERY TAIL END OF OUR
WEEKEND FRONTAL SYSTEM SUNDAY NIGHT...AND THE NEXT FRONTAL SYSTEM
WHICH LOOKS TO HOLD OFF UNTIL WEDNESDAY NIGHT INTO THURSDAY.
THUS...A DRY FORECAST WILL HOLD THROUGH MUCH OF THE PERIOD.
VERY LOW POPS EARLY IN THE PERIOD REASONABLE...AND ANY REMAINING
PRECIP SHOULD BE ALL SNOW BY THEN. ADDITIONALLY...LATE WEEK SYSTEM
SHOULD BE COLD ENOUGH TO BE ALL SNOW AS WELL. NOTHING SIGNIFICANT
APPEARING ON THE HORIZON JUST YET.
TEMPERATURES WERE INITIALIZED REASONABLY...WITH A BIT OF A ROLLER
COASTER RIDE THROUGH THE HOLIDAY WEEK. SEE LITTLE OPPORTUNITY FOR
IMPROVEMENT OVER A BLEND.
&&
.AVIATION /DISCUSSION FOR 200600Z TAF ISSUANCE/...
ISSUED AT 1142 PM EST THU DEC 19 2013
STEADILY DETERIORATING CONDITIONS FOR AVIATORS WITH LIFR
CONDITIONS DEVELOPING FOR MUCH OF FRIDAY.
FRONTAL BOUNDARY EXTENDING FROM SOUTHERN LOWER MICHIGAN W/SW INTO
NORTH CENTRAL ILLINOIS LATE THIS EVENING. STRENGTHENING LOW LEVEL
JET CONTINUES TO BRING GULF MOISTURE INTO THE OHIO VALLEY. RH
PROGS AT 950/925MB OFF THE RAP INDICATE SUBTLY DRIER AIR LIFTING
NORTH ACROSS CENTRAL INDIANA...AND THIS HAS LIKELY DELAYED
CEILINGS FROM FALLING BELOW VFR. AS DEEPER MOISTURE AND LIGHT RAIN
SHOWERS EXPAND INTO THE FORECAST AREA OVERNIGHT...EXPECT IFR
CEILINGS TO BECOME PREVALENT PRIOR TO DAYBREAK...DROPPING TO 500FT
OR LOWER AS THE INVERSION STRENGHTENS DURING THE MORNING.
RAIN WILL CONTINUE AS WELL THROUGH MUCH OF THE DAY AS A SURFACE
WAVE TRAVERSES THE NEARLY STATIONARY BOUNDARY JUST TO THE
NORTHWEST OF THE REGION. SLIGHTLY DRIER AIR ALOFT ATTEMPTS TO
BRIEFLY WORK INTO THE REGION BEHIND THE SURFACE WAVE LATE FRIDAY
AFTERNOON BUT WITH SATURATED CONDITIONS TRAPPED BENEATH THE
INVERSION...MAY ONLY SEE RAIN LIGHTEN TO DRIZZLE FOR A FEW HOURS.
MORE WIDESPREAD AND HEAVIER RAINFALL WILL QUICKLY EXPAND INTO
CENTRAL INDIANA NEAR THE END OF THE FORECAST PERIOD AS DEEPER
MOISTURE ADVECTS INTO THE OHIO VALLEY.
LOW LEVEL WIND SHEAR WILL REMAIN A FACTOR THROUGH THE FIRST 12
HOURS OF THE FORECAST WITH THE PRESENCE OF THE LOW LEVEL JET. RAP
INDICATING POTENTIAL FOR SOUTHWEST WINDS TO APPROACH 60KTS
OVERNIGHT IN THE 2-3KFT LAYER. LLWS CONCERNS WILL NOT DIMINISH
UNTIL EARLY AFTERNOON AS THE LOW LEVEL JET WEAKENS. SOUTHWEST
WINDS AT 10 TO 15 KTS ARE EXPECTED THROUGH MUCH OF THE PERIOD...
VEERING TO MORE OF A WESTERLY DIRECTION FRIDAY EVENING AS THE
BOUNDARY SAGS INTO THE FORECAST AREA.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM LATE TONIGHT THROUGH SUNDAY MORNING FOR INZ021-
028>031-035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...PUMA
NEAR TERM...PUMA
SHORT TERM...PUMA
LONG TERM...NIELD
AVIATION...RYAN
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1142 PM EST THU DEC 19 2013
.UPDATE...
THE AVIATION SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 300 PM EST THU DEC 19 2013
A LOW PRESSURE TROUGH FROM TEXAS TO THE GREAT LAKES WILL WILL SETTLE
INTO THE OHIO VALLEY THIS WEEKEND. A COUPLE OF SHORT WAVES EMBEDDED
WITHIN THE TROUGH WILL PRODUCE SEVERAL SURGES OF RAINFALL WITH THE
INITIAL RAIN BEING LIGHT THROUGH FRIDAY EVENING. THE SECOND WAVE
WILL BRING SUBSTANTIAL RAIN SATURDAY BEFORE IT DEPARTS THE REGION
SUNDAY. COLD HIGH PRESSURE WILL BUILD INTO THE REGION TO START THE
WEEK. A WEAK LOW PRESSURE TROUGH WILL MOVE INTO THE GREAT LAKES AND
OHIO VALLEY NEXT THURSDAY AND MAY PRODUCE SOME LIGHT SNOW.
ABOVE NORMAL TEMPERATURES WILL PREVAIL INTO FRIDAY THEN RETURN TO
NORMAL AND THEN BELOW NORMAL BY SUNDAY NIGHT AND REMAIN BELOW NORMAL
MOST OF NEXT WEEK.
&&
.NEAR TERM /REST OF TONIGHT/...
ISSUED AT 928 PM EST THU DEC 19 2013
DECENT LIFT ONGOING ACROSS THE AREA THIS EVENING ALONG A 35-40 KT
LOW LEVEL JET...HOWEVER DEEPER MOISTURE FOR PRECIPITATION IS STILL
LACKING A BIT BASED ON THIS EVENING/S UPPER AIR. STILL APPEARS SOME
PRECIPITATION WILL DEVELOP LATER TONIGHT UNDER SUSTAINED WARM/MOIST
ADVECTION...BUT IT MAY HOLD OFF UNTIL THE EARLY MORNING HOURS ON
FRIDAY.
TEMPERATURES HAVE HELD NEARLY STEADY THIS EVENING...AND WITH WARM
ADVECTION CONTINUING TONIGHT...THINK IT WILL BE TOUGH FOR
TEMPERATURES TO REACH THE CURRENT FORECAST LOWS...ESPECIALLY OVER
THE SOUTH. WILL ALLOW FOR A SLIGHT FALL TO THE TEMPERATURES FOR THE
REST OF THE NIGHT.
PREVIOUS DISCUSSION FOLLOWS.
MODELS SIMILAR AND WILL USE A BLEND. FIRST UPPER WAVE AND ASSOCIATED
SURFACE LOW WILL LIFT NORTHEAST TO NEAR QUINCY BY FRIDAY MORNING.
INCREASING LIFT WILL CONTINUE MOISTENING ATMOSPHERE COLUMN AND BY
MIDNIGHT SHOULD BEGIN TO SPREAD VERY LIGHT RAIN ACROSS CENTRAL
INDIANA. MILD SOUTHWEST FLOW CONTINUING WILL RESULT IN MINIMUM
TEMPERATURES AT OR NEAR LAST NIGHTS VALUES OR IN THE UPPER 30S TO
LOWER 40S.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY/...
ISSUED AT 300 PM EST THU DEC 19 2013
ISSUE FOR THIS PERIOD IS WHERE THE HEAVY RAIN AXIS WILL END UP.
MODELS STILL VARY A BIT WITH DIFFERENCES IN SURFACE LOW TRACK
WHICH TIES TO HEAVY RAIN AXIS. WILL CONTINUE TO USE A BLEND OF
MODELS TO AVERAGE RAIN AMOUNTS ACROSS THE FORECAST AREA AND
INCLUDE HPC EXCESSIVE RAINFALL GUIDANCE AS WELL AS RIVER FORECAST
CENTER QUANTITATIVE PRECIPITATION FORECASTS AS PART OF BLEND.
FRIDAY AND FRIDAY NIGHT...
DURING THIS TIME FRAME ALL MODELS LIFT THE INITIAL SURFACE LOW FROM
THE MID MISSISSIPPI VALLEY FRIDAY MORNING TO THE NEW ENGLAND
SATURDAY MORNING. THIS WAVE WILL PRODUCE PERIODS OF LIGHT RAIN AND
WILL SETTLE A COLD FRONT SURFACE BOUNDARY TO A POSITION NEAR THE
OHIO RIVER. ON SOUTHWEST WINDS...TEMPERATURES SURGE INTO THE 50S FOR
MOST AREAS FRIDAY THEN SETTLE BACK INTO THE MID 30S NORTH TO MID 40S
SOUTH BY DAYBREAK SATURDAY.
SATURDAY INTO SUNDAY MORNING...
MODELS DIFFER SOME ON TRACK OF THE MAIN WAVE AND SURFACE LOW LIFTING
INTO THE REGION SO WILL AGAIN CONTINUE A BLEND BUT LEAN TOWARDS A
TRACK UP INTO AND ACROSS OUR SOUTHERN COUNTIES.
ALL MODELS SHOW A STRONG THERMAL BOUNDARY AND STRONG JET DYNAMICS
YIELDING SUBSTANTIAL LIFT OF UNUSUALLY MOIST AIR ORIGINATING IN LOW
LATITUDES BASED ON WATER VAPOR IMAGES...RESULTING IN SUBSTANTIAL AND
PROLONGED RAINS FROM SATURDAY MORNING INTO SUNDAY MORNING. AXIS OF
HEAVIEST PRECIPITATION WILL BE PLACED NEAR BUT JUST SOUTH HPC
PRECIPITATION GUIDANCE IN LINE WITH RIVER FORECAST CENTER. RAIN
AMOUNTS FROM 2 INCHES NORTH TO 4 INCHES SOUTH STILL APPEAR LIKELY
DURING THIS 24 HOUR PERIOD. AGAIN MODEL DIFFERENCES SUGGEST A TRACK
FURTHER NORTH THAN THIS PUSHES HEAVY RAIN AXIS ALONG AND NORTH OF
I-70 AND ALSO BRINGS MILDER TEMPERATURES SATURDAY NIGHT AND SUNDAY
CLOSER TO I-70. DRY SLOT WRAPS IN AFTER MIDNIGHT SATURDAY NIGHT WILL
BRING AND END TO HEAVIEST RAIN.
SUNDAY...
DRY SLOT STILL IN PLAY SUNDAY AS COLD FRONT SWEEPS COLDER AIR IN
BEGINNING SUNDAY MORNING. WRAP AROUND CLOUD SHIELD WILL MOVE INTO
CENTRAL INDIANA SUNDAY AFTERNOON AND BRING A MIX OF LIGHTER RAIN
SHOWERS AND SNOW SHOWERS THAT TRANSITION INTO ALL SNOW SHOWERS
BEFORE NIGHTFALL. NO SNOW ACCUMULATION IS EXPECTED.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
ISSUED AT 205 PM EST THU DEC 19 2013
LONG TERM PERIOD WILL GENERALLY BE A QUIET ONE WITH STRONG HIGH
PRESSURE TRAVERSING THE REGION IN BETWEEN THE VERY TAIL END OF OUR
WEEKEND FRONTAL SYSTEM SUNDAY NIGHT...AND THE NEXT FRONTAL SYSTEM
WHICH LOOKS TO HOLD OFF UNTIL WEDNESDAY NIGHT INTO THURSDAY.
THUS...A DRY FORECAST WILL HOLD THROUGH MUCH OF THE PERIOD.
VERY LOW POPS EARLY IN THE PERIOD REASONABLE...AND ANY REMAINING
PRECIP SHOULD BE ALL SNOW BY THEN. ADDITIONALLY...LATE WEEK SYSTEM
SHOULD BE COLD ENOUGH TO BE ALL SNOW AS WELL. NOTHING SIGNIFICANT
APPEARING ON THE HORIZON JUST YET.
TEMPERATURES WERE INITIALIZED REASONABLY...WITH A BIT OF A ROLLER
COASTER RIDE THROUGH THE HOLIDAY WEEK. SEE LITTLE OPPORTUNITY FOR
IMPROVEMENT OVER A BLEND.
&&
.AVIATION /DISCUSSION FOR 200600Z TAF ISSUANCE/...
ISSUED AT 1142 PM EST THU DEC 19 2013
STEADILY DETERIORATING CONDITIONS FOR AVIATORS WITH LIFR
CONDITIONS DEVELOPING FOR MUCH OF FRIDAY.
FRONTAL BOUNDARY EXTENDING FROM SOUTHERN LOWER MICHIGAN W/SW INTO
NORTH CENTRAL ILLINOIS LATE THIS EVENING. STRENGTHENING LOW LEVEL
JET CONTINUES TO BRING GULF MOISTURE INTO THE OHIO VALLEY. RH
PROGS AT 950/925MB OFF THE RAP INDICATE SUBTLY DRIER AIR LIFTING
NORTH ACROSS CENTRAL INDIANA...AND THIS HAS LIKELY DELAYED
CEILINGS FROM FALLING BELOW VFR. AS DEEPER MOISTURE AND LIGHT RAIN
SHOWERS EXPAND INTO THE FORECAST AREA OVERNIGHT...EXPECT IFR
CEILINGS TO BECOME PREVALENT PRIOR TO DAYBREAK...DROPPING TO 500FT
OR LOWER AS THE INVERSION STRENGHTENS DURING THE MORNING.
RAIN WILL CONTINUE AS WELL THROUGH MUCH OF THE DAY AS A SURFACE
WAVE TRAVERSES THE NEARLY STATIONARY BOUNDARY JUST TO THE
NORTHWEST OF THE REGION. SLIGHTLY DRIER AIR ALOFT ATTEMPTS TO
BRIEFLY WORK INTO THE REGION BEHIND THE SURFACE WAVE LATE FRIDAY
AFTERNOON BUT WITH SATURATED CONDITIONS TRAPPED BENEATH THE
INVERSION...MAY ONLY SEE RAIN LIGHTEN TO DRIZZLE FOR A FEW HOURS.
MORE WIDESPREAD AND HEAVIER RAINFALL WILL QUICKLY EXPAND INTO
CENTRAL INDIANA NEAR THE END OF THE FORECAST PERIOD AS DEEPER
MOISTURE ADVECTS INTO THE OHIO VALLEY.
LOW LEVEL WIND SHEAR WILL REMAIN A FACTOR THROUGH THE FIRST 12
HOURS OF THE FORECAST WITH THE PRESENCE OF THE LOW LEVEL JET. RAP
INDICATING POTENTIAL FOR SOUTHWEST WINDS TO APPROACH 60KTS
OVERNIGHT IN THE 2-3KFT LAYER. LLWS CONCERNS WILL NOT DIMINISH
UNTIL EARLY AFTERNOON AS THE LOW LEVEL JET WEAKENS. SOUTHWEST
WINDS AT 10 TO 15 KTS ARE EXPECTED THROUGH MUCH OF THE PERIOD...
VEERING TO MORE OF A WESTERLY DIRECTION FRIDAY EVENING AS THE
BOUNDARY SAGS INTO THE FORECAST AREA.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH FROM LATE FRIDAY NIGHT THROUGH SUNDAY MORNING FOR
INZ021-028>031-035>049-051>057-060>065-067>072.
&&
$$
SYNOPSIS...TUCEK
NEAR TERM...TUCEK/JAS
SHORT TERM...TUCEK
LONG TERM...NIELD
AVIATION...RYAN
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AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
929 PM CST SAT DEC 21 2013
.UPDATE...
ISSUED AT 922 PM CST SAT DEC 21 2013
NO MAJOR CHANGES HAVE BEEN MADE THIS EVENING WITH REGARD TO THE
IMPACTS OF THE WINTER STORM. HOWEVER...HERE IS AN UPDATE OF WHERE
THINGS STAND. WE ARE IN THE BRIEF LULL IN STRONG FORCING BETWEEN
THE EARLIER WAA PCPN OVER THE SOUTHEAST 1/3 AND THE UPCOMING
STRONG DEFORMATION ZONE SPREADING NORTHEAST FROM MISSOURI. IN THE
MEAN TIME...WIDESPREAD LIGHT FREEZING DRIZZLE/LIGHT SNOW/LIGHT
SLEET CONTINUES OVER THE CWA. THE SNOW TO SLEET LINE SEEMS TO
CURRENTLY BE FROM NEAR BURLINGTON TO JUST EAST OF MOLINE...TO
DE KALB ILLINOIS. NORTHWEST OF THIS LINE...THE DOMINANT P-TYPE IS
SNOW...AND IT WILL CONTINUE TO BE SO. THE RAP MODEL WHICH IS
HANDLING THE 800MB WARM WEDGE NOTED ON THE 00Z DVN
SOUNDING...SHOWS A TRANSITION TO SNOW OVER THE REMAINING CWA
BETWEEN NOW AND 3 AM. HRRR AND RAP...ALONG WITH THE 00Z NAM
INDICATE THE DEFORMATION ZONE SHOULD HIT HARD SOMETIME ABOUT 10 PM
WEST...11 CENTRAL...TO MIDNIGHT NORTHEAST. IT SHOULD LAST THROUGH
15Z OR SO BEFORE RAPIDLY LIFTING NORTH OUT OF THE REGION.
THUS...HEAVY SNOW RATES FOR ABOUT 5 HOURS SEEM LIKELY IN OUR
WESTERN 1/2 TO 2/3RD...MATCHING AMOUNTS WELL ENOUGH NOT THE CHANGE
THEM.
ERVIN
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 318 PM CST SAT DEC 21 2013
VIGOROUS WINTER STORM NOW IMPINGING ON THE REGION. STORM IS
LARGELY EVOLVING AS FORECAST. WARM WEDGE ALOFT RESULTING IN FREEZING
RAIN OVER WEST CENTRAL AND CENTRAL ILLINOIS. SURFACE LOW NOW OVER
ARKANSAS WILL TRACK UP THE OHIO VALLEY. EXPECT TO SEE PRECIP
SHIELD SPREAD BACK TO THE NORTHWEST SLIGHTLY MORE INTO OUR AREA AS
THE LOW PASSES TO OUR SOUTHEAST...RESULTING ANOTHER PERIOD OF
MIXED PRECIP THIS EVENING FOR SOUTHEAST. FORECAST SOUNDINGS VIA
AWIPS AND BUFKIT SHOW CONTINUED POTENTIAL FOR FREEZING RAIN UNTIL
MIDNIGHT THEN FAIRLY RAPID TRANSITION TO SNOW AS THE MAIN WAVE
APPROACHES.
MAIN SNOWFALL EVENT WILL BE ASSOCIATED WITH THE DEFORMATION ZONE
MOVING ACROSS THE AREA TONIGHT. ENERGY ASSOCIATED WITH PRECIP NOW
OVER EASTERN OK AND KS WILL CONGEAL INTO INTENSE DEFORMATION ZONE
ACROSS NORTHERN MO AND EASTERN IA THIS EVENING. IMPRESSIVE
MOISTURE FOR THIS TIME OF YEAR WILL ONLY BE OFFSET BY RAPID
MOVEMENT OF SYSTEM. STILL...WE ARE LOOKING AT A PERIOD OF INTENSE
SNOWFALL RATES FROM LATE EVENING INTO EARLY MORNING.
WINDS BEGIN TO INCREASE TOWARD MORNING...CREATING POTENTIAL FOR
BLOWING SNOW ISSUES...ESPECIALLY IN RURAL AREAS SUNDAY.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 318 PM CST SAT DEC 21 2013
LIGHT SNOW FROM THE WINTER STORM WILL CONTINUE INTO SUNDAY EVENING
AND SLOWLY END ALONG WITH DECREASING WINDS. CLOUD COVER WILL AID IN
KEEPING TEMPERATURES UP BUT THE POSSIBILITY DOES EXIST THAT
HEADLINES FOR WIND CHILL MIGHT BE NEEDED OVER PART OF THE WESTERN
THIRD LATE SUNDAY NIGHT INTO MONDAY MORNING.
WRAP AROUND MOISTURE AND COLD AIR MOVING INTO THE AREA IS EXPECTED
TO KEEP FLURRIES OR VERY LIGHT SNOW GOING FOR A GOOD PART OF MONDAY
OVER THE NORTHEAST HALF OF THE AREA. THE STRENGTH OF THE COLD AIR
MOVING INTO THE AREA IS EXPECTED TO KEEP TEMPERATURES IN THE SINGLE
DIGITS OVER MUCH OF THE AREA.
ARCTIC HIGH PRESSURE MOVES ACROSS THE AREA MONDAY NIGHT INTO TUESDAY
RESULTING IN DRY CONDITIONS BUT BITTER COLD TEMPERATURES. BASED ON
PROJECTED LOWS AND WINDS...HEADLINES FOR WIND CHILL WOULD BE NEEDED
MONDAY NIGHT INTO TUESDAY MORNING.
SKIES SHOULD CLEAR MONDAY NIGHT AND WHEN COMBINED WITH FRESH SNOW
AND DECREASING WINDS IS EXPECTED TO PUSH LOW TEMPERATURES WELL BELOW
ZERO OVER MUCH OF THE AREA. LOWS MAY PUSH 20 BELOW IN THE FAVORED
COLD AREAS WEST OF THE MISSISSIPPI.
ON TUESDAY DRY CONDITIONS BUT VERY COLD TEMPERATURES WILL BE SEEN
ACROSS THE AREA. THE NORTHERN THIRD TO 40 PERCENT OF THE AREA WILL
STRUGGLE TO GET ABOVE 10 DEGREES.
TUESDAY NIGHT ON...
THE MODEL CONSENSUS HAS SLIGHT CHANCE/CHANCE POPS TUES NIGHT/WED AND
SLIGHT CHANCE POPS WED NIGHT AS THE NEXT DISTURBANCE MOVES THROUGH
THE AREA. MOISTURE WILL BE VERY LIMITED BUT SNOW/RAIN RATIOS WILL BE
HIGH. SO WHAT MOISTURE IS AVAILABLE WILL GO INTO PRODUCING A VERY
DRY SNOW. A REASONABLE GUESS ON AMOUNTS THIS FAR OUT WOULD BE AROUND
AN INCH WITH PERHAPS A BIT MORE ACROSS THE NORTHERN THIRD OF THE
AREA.
THE NEXT ARCTIC HIGH BUILDS INTO THE MIDWEST THURSDAY INTO FRIDAY
RESULTING IN DRY CONDITIONS BUT TEMPERATURES WELL BELOW NORMAL. THE
MODEL CONSENSUS DEVELOPS WARMER RETURN FLOW FRIDAY NIGHT INTO
SATURDAY WITH DRY CONDITIONS AND BUT TEMPERATURES WILL REMAIN BELOW
NORMAL.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 526 PM CST SAT DEC 21 2013
IFR CONDITIONS TO LIFR CONDITIONS WILL PRECEDE A LARGE WINTER
STORM OVERNIGHT AND SUNDAY IN EASTERN IOWA AND ILLINOIS. NORTHEAST
WINDS WILL BECOME NORTHWEST BY LATE TONIGHT...AND CONTINUE TO BE
15 TO 20 KTS...GUSTING TO MID 20S AT TIMES. CIGS OF 200 FT TO 800
FT WILL BE COMMON THROUGH SUNDAY AFTERNOON WITH FREEZING RAIN AND
SLEET CHANGING TO MODERATE TO HEAVY SNOW OVERNIGHT IN ALL
LOCATIONS. SNOW WILL END BY MID DAY SUNDAY...BUT FOLLOWING THIS
TIME...BLOWING AND DRIFTING SNOW CAN BE EXPECTED TO CONTINUE TO
BRING IFR CONDITIONS TO ALL TERMINALS THROUGH LATE SUNDAY
AFTERNOON. THIS IS A VERY POOR FLYING FORECAST...WITH SHORT TERM
ICING AT TERMINALS FOLLOWED BY HEAVY SNOW.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR BENTON-BUCHANAN-
CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE-HENRY IA-IOWA-
JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-LINN-LOUISA-
MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR BUREAU-CARROLL-
HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER-
PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.
MO...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR CLARK-SCOTLAND.
&&
$$
UPDATE...ERVIN
SHORT TERM...DMD
LONG TERM...08
AVIATION...ERVIN
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1130 PM CST THU DEC 19 2013
.UPDATE...
ISSUED AT 802 PM CST THU DEC 19 2013
BASED ON CURRENT TRENDS...HAVE MOVED UP THE ONSET OF THE FREEZING
RAIN ADVISORY FOR THE EASTERN SEGMENT THAT WAS PREVIOUSLY SET TO
BEGIN AT MIDNIGHT...TO 10 PM. ALSO...ADDED FAR NORTHWEST ILLINOIS
COUNTIES TO THE CURRENT ADVISORY AREA.
AT 745 PM...KDVN RADAR SHOWED WIDESPREAD LIGHT RAIN ACROSS THE CENTRAL
AND NORTHERN PORTIONS OF THE FORECAST AREA WITH WIDESPREAD
DRIZZLE THE ENTIRE AREA NORTH OF HIGHWAY 34. THE FREEZING LINE AT
THE SURFACE WAS ROUGHLY ALONG A LINE FROM WESTERN STEPHENSON COUNTY
IL...TO CEDAR RAPIDS AND SOUTHWEST TO NEAR PELLA. SURFACE
OBSERVATIONS WERE INDEED REPORTING FREEZING RAIN NW OF THIS LINE.
USED RAP MODEL TRENDS TO TRANSITION THE 32 DEGREE LINE AND
FREEZING PRECIP AREA SOUTHEAST THIS EVENING AND OVERNIGHT.
THE PRECIPITATION SHOULD CONTINUE UNTIL THE WAVE OF LOW PRESSURE
STILL OUT OVER THE OK PANHANDLE PASSES TO OUR SOUTHEAST THROUGH
CENTRAL IL FRIDAY AFTERNOON. WITH THIS TIMING...THE PRECIPITATION
SHOULD CONTINUE THROUGH MOST OF FRIDAY MORNING...WHEN LOW LEVEL
COLD ADVECTION SHOULD CHANGE THE PRECIPITATION OVER TO LIGHT SNOW
AND POSSIBLY SLEET ACROSS THE NORTHWEST.
&&
.SYNOPSIS...
ISSUED AT 330 PM CST THU DEC 19 2013
A FRONTAL BOUNDARY REMAINS DRAPED ACROSS THE AREA THIS AFTERNOON...
ROUGHLY ALONG INTERSTATE 80. MOISTURE IS POOLING ALONG AND SOUTH
OF THE FRONT...EVIDENT BY DEW POINTS THAT HAVE CLIMBED INTO THE
30S AND EVEN LOWER 40S. TO THE NORTH...DEW POINTS ARE IN THE MID
AND UPPER 20S. FOG NEVER DID FORM TODAY...WITH VISIBILITIES GENERALLY
REMAINING OVER 6 MILES...WITH ONLY A FEW SITES DROPPING TO 4-6SM
FOR ONLY AN HOUR OR TWO. HIGH LEVEL CLOUDS BLANKET THE AREA...WITH
SOME LOW LEVEL STRATUS JUST NOW OVER THE PAST HOUR/TWO FORMING
OVER AREAS SOUTH OF I 80. AS OF 3 PM...TEMPERATURES RANGE FROM THE
LOWER 30S ALONG HIGHWAY 20...TO THE UPPER 40S AND LOWER 50S IN
NORTHEAST MO.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 330 PM CST THU DEC 19 2013
GENERAL SHORT TERM FORECAST HAS NOT CHANGED MUCH...OTHER THAN
WITH ABOUT A 6 HOUR DELAY. STILL EXPECT LIGHT RAIN AND FREEZING
RAIN TO DEVELOP ACROSS THE AREA THIS EVENING AND ESPECIALLY
OVERNIGHT. NO CHANGE TO GOING FREEZING RAIN ADVISORY AREAL
COVERAGE...HOWEVER WE HAVE EXTENDED IT UNTIL MID MORNING FRIDAY.
DO NOT EXPECT THAT MUCH RAINFALL WITH THIS EVENT...WITH MOST AREAS
SEEING A FEW HUNDREDTHS OF AN INCH TO UNDER A TENTH. MINOR ICE
ACCUMULATIONS OR A LIGHT GLAZE WILL STILL BE POSSIBLE ON UNTREATED
SURFACES LATE TONIGHT THROUGH THE MORNING COMMUTE FRIDAY FOR AREAS
IN THE ADVISORY. SEE THE LATEST WINTER WEATHER MESSAGE FOR MORE
INFORMATION. LOWS TONIGHT WILL RANGE FROM AROUND 20 IN THE NW
CWFA...TO THE MID 30S IN PARTS OF WEST CENTRAL IL.
ONLY A SLIGHT RISE IN TEMPS IS EXPECTED FRIDAY...AS THE WINTRY
MIX OF -RA/-FZRA/-SN SLOWLY EXITS TO THE EAST AND NORTH WINDS
USHER COLD AIR INTO THE AREA. THE NW 1/3 OF THE AREA MAY SEE THE
PCPN CHANGE TO ALL SNOW BEFORE ENDING DURING THE DAY FRIDAY WITH
ONLY A DUSTING OF ACCUMULATION POSSIBLE.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 330 PM CST THU DEC 19 2013
A WINTER STORM WILL IMPACT THE CWA SATURDAY NIGHT AND SUNDAY. FOR
THIS POTENTIAL...WHICH IS COMPLICATED IN MANY WAYS...A WINTER
STORM WATCH HAS BEEN ISSUED FOR ALL COUNTIES FROM 00Z SUN TO 00Z
MONDAY.
UPPER AIR OBSERVATIONS CONFIRM A STRONG UPPER LOW IS DIGGING
SOUTHEAST THROUGH CALIFORNIA TODAY...AND WILL BE KICKED OUT OF THE
BASE OF THE TROF BY A STRONG 150KT JET STREAK OBSERVED AT 300MB.
THIS WILL SET THE STAGE FOR CYCLOGENESIS ALONG THE FRONTAL BOUNDARY
WHICH WILL BE STALLED TO OUR SOUTH FRIDAY NIGHT. GUIDANCE IS IN
FAIRLY GOOD AGREEMENT THAT THE SURFACE LOW WILL PASS FROM NEAR
SOUTHWEST MO SATURDAY AFTERNOON...TO NORTHERN INDIANA BY SUNDAY
MORNING. THE UPPER LOW SHOULD EJECT NORTHEAST...WITH MODELS AGREEING
A TRACK THROUGH THE CWA AS A PARTIALLY CLOSED OFF 500MB LOW OCCURRING
ABOUT 12Z SUNDAY. THIS SYNOPTICALLY SETS THE STAGE FOR A SIGNIFICANT
WINTER STORM FOR OUR CWA AND MUCH OF THE MIDWEST. HEAVY RAINS WILL
TAKE PLACE A BIT FARTHER SOUTHEAST...FROM FRIDAY THROUGH SUNDAY.
THERMALLY...MODELS ARE A BIT COLDER THAN LAST NIGHTS RUNS...AND I
HAVE ADJUSTED THE SLEET/ZR TRANSITION TO SNOW A BIT FARTHER EAST.
HOWEVER...IT MAY BE SEEN THAT A SIGNIFICANT AMOUNT OF QPF FOR THIS
EVENT FALLS AS SLEET AND POSSIBLE RA/ZR IN THE SOUTHEAST AND FAR
EAST. WEST OF A LINE FROM BURLINGTON TO STERLING ILLINOIS...THIS
EVENT SHOULD BE DOMINATED BY SNOW SATURDAY NIGHT AND SUNDAY.
THUS...AMOUNTS WILL SEE A STEEP GRADIENT FROM 6-8 INCHES WIDESPREAD
IN THE IOWA AND FAR WESTERN IL COUNTIES...TO UNDER 4 INCHES IN THE
EAST. THOUGH AMOUNTS SHOULD BE UNDER 6 INCHES IN THE EAST AND
SOUTHEAST...IT DOES APPEAR THAT SLEET AND FREEZING RAIN MAY BE
ENOUGH OF A THREAT TO WARRANT A WATCH INCLUSION. BLOWING SNOW IN
OPEN AREAS...AND WIDESPREAD SIGNIFICANT DRIFTING SHOULD CONTINUE
THROUGH SUNDAY AFTERNOON...AND THE WATCH WILL BE CONTINUED THROUGH
6PM FOR THIS REASON.
BEYOND THIS...TEMPERATURES CONTINUE TO BE COOLED IN THIS GUIDANCE
BLEND FORECAST OF THE EXTENDED. WE WILL CERTAINLY KEEP WHAT SNOW
COVER IS ON THE GROUND SUNDAY AFTERNOON THROUGH DECEMBER 25. YOU
GUESSED IT...ITS GOING TO BE A WHITE CHRISTMAS IN MUCH OF THE UPPER
MIDWEST.
ERVIN
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1129 PM CST THU DEC 19 2013
A WAVE OF LOW PRESSURE MOVING ALONG A SLOW MOVING COLD FRONT WILL
CONTINUE TO RESULT IN LIGHT FREEZING RAIN AND DRIZZLE OVER THE
REGION OVERNIGHT INTO EARLY FRIDAY. LATE THURSDAY EVENING...
PRECIPITATION WAS FREEZING ON PAVED SURFACES AT CID AND
DBQ...WHILE MLI AND BRL REMAINED JUST ENOUGH ABOVE FREEZING
RESULTING IN LIQUID PRECIPITATION. THIS FREEZING LINE WILL
GRADUALLY MOVE SOUTHEAST TOWARD MORNING...POSSIBLY RESULTING IN A
LIGHT GLAZING ON RUNWAYS AT MLI FRIDAY MORNING. OTHERWISE...DEEP
LOW LEVEL MOISTURE WILL LINGER KEEPING WIDESPREAD IFR AND LIFR
CONDITIONS DUE TO LOW CLOUDS AND FOG IN PLACE TONIGHT THROUGH MUCH
OF FRIDAY. WHILE THE PRECIPITATION IS EXPECTED TO END FRIDAY
AFTERNOON...CIGS ARE EXPECTED TO REMAIN BELOW 1000 FT WELL INTO
FRIDAY EVENING.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...FREEZING RAIN ADVISORY UNTIL 9 AM CST FRIDAY FOR BENTON-BUCHANAN-
CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE-HENRY IA-IOWA-
JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LINN-LOUISA-
MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-DES
MOINES-DUBUQUE-HENRY IA-IOWA-JACKSON-JEFFERSON-JOHNSON-
JONES-KEOKUK-LEE-LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-
WASHINGTON.
IL...FREEZING RAIN ADVISORY UNTIL 9 AM CST FRIDAY FOR CARROLL-JO
DAVIESS-MERCER-ROCK ISLAND-STEPHENSON-WHITESIDE.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR BUREAU-CARROLL-HANCOCK-HENDERSON-HENRY IL-JO
DAVIESS-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-STEPHENSON-
WARREN-WHITESIDE.
MO...FREEZING RAIN ADVISORY UNTIL 9 AM CST FRIDAY FOR SCOTLAND.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR CLARK-SCOTLAND.
&&
$$
UPDATE...SHEETS
SYNOPSIS...14
SHORT TERM...14
LONG TERM...ERVIN
AVIATION...SHEETS
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
210 PM CST Fri Dec 20 2013
...Updated Long Term Section...
.SHORT TERM...(Today and tonight)
ISSUED AT 340 AM CST FRI DEC 20 2013
The approaching winter weather will be covered in the long
term discussion since the vast majority of winter weather
is expected after 12z Saturday.
Cold high pressure will be centered over Nebraska and South Dakota
today, but the southern periphery of the high will be wedged into
southwestern Kansas. It is a tough call as to whether the low stratus
clouds will clear out, allowing temperatures to modify a little
today. The NAM and SREF indicate clearing with highs around 33F at
Dodge City, 30F at Hays and 36 at Elkhart, while the RAP holds
onto the stratus for areas east of Garden City, with much cooler
highs in upper teens to lower and mid 20s. Opted to go with an in
between solution due to the uncertainty, with mid to high 20s at
Hays, Dodge City and Pratt, and lower 30s in far southwestern and
Western Kansas. Some mid to high level cloud will be increasing
late today in advance of the aforementioned upper level trough. By
tonight, mid level cloud will continue to increase over southwestern
Kansas, with only limited radiational cooling in the brief clear
breaks. Temperatures should bottom out in the upper teens to lower
20s, but could be lower if temperatures stay colder today.
.LONG TERM...(Saturday night through Friday)
ISSUED AT 209 PM CST FRI DEC 20 2013
After the strong upper level cyclone near the Arizona/old Mexico
border lifts out across the central United States Saturday and
Saturday night, a period of quiet weather should return to western
Kansas. Sea surface temperatures remain very warm in the north
Pacific with a large warm pool more than 2C above climatology
centered near 150W 45N. Vigorous low pressure systems west of the
warm pool have carried warm air northward and have supported a
persistent high amplitude upper level ridge around 140W to 150W
since late November. Surface anticyclogenesis downstream from
the ridge has favored maintenance of a large pool of very cold air
in Canada with frequent incursions of frigid air into the United
States. There is little indication that a major adjustment
will occur in the near term, although the CFS and the multi-model
ensemble solutions persist in developing warm temperatures in
western Canada in January.
Tropical thunderstorms remain active across much of the Indian Ocean
south of the equator and over the Maritime Continent into eastern
Asia. There have been several fast moving Kelvin waves that have
rippled through the tropics, but there has been little coherent
propagation that projects onto a Madden-Julian Oscillation. The CFS
persists in propagating a Madden-Julian Oscillation into the western
hemisphere in early January, but most of the other models are much
less aggressive. The typical response to an eastward propagating
Madden Julian Oscillation in Phases 5 and 6 of the Wheeler-Hendon
phase space diagram is warmer than average temperatures in the
Midwest and eastern United States. Given doubts about evolution of
the Madden-Julian Oscillation, confidence in the warm temperatures
in early January is very low.
Atmospheric relative angular momentum remains below climatological
averages, but mountain torque contribution from Asia has been
positive in recent days. The tendency of atmospheric relative
angular momentum is strongly positive, and the atmosphere likely
will remain in Phase 4 of the Weickmann Berry Global Wind
Oscillation phase space diagram for a few days. Phase 4 correlates
with anticyclonic flow in the western United States, so the concept
of building heights in the western part of the country and
progressing the long wave trough to the Mississippi Valley by 26-27
December is reasonable. As such, the really frigid air probably will
remain east of western Kansas next week, although there will be
occasional glancing blows of arctic air through early January.
Progression of the long wave pattern will be less favorable for
anticyclonic wave breaks in the southwestern United States, and the
potential for significant precipitation in this part of the world is
low for the rest of December.
Stratospheric temperatures have become anomalously warm at 10mb in
the eastern United States since early December, and stratospheric
temperatures have been warming at 30mb and 50mb over the North
Atlantic. Whether this will support maintenance of a blocky
anticyclone in the North Atlantic and persistence of the mean trough
in the eastern United States remains to be seen, but the atmosphere
seems to favor this pattern. The atmosphere likely will continue to
be characterized by ridging near the west coast and a mean trough in
the eastern part of the country through at least the first part of
January.
In the nearer term, snowfall will wind down quickly Saturday
evening, and skies should become partly cloudy on Sunday. Cold air
and snow cover in much of southwest Kansas will keep temperatures
below freezing Sunday. A minor upper level trough embedded in strong
northwest flow will approach northern Kansas Sunday night, and mid
level frontogenesis will favor development of widespread mid level
cloudiness and scattered snow flurries. Temperatures south of the
mid level cloud shield will radiate to near zero over the snow field
with somewhat warmer temperatures in west central Kansas, where snow
cover is likely to be minimal to nonexistent. Low level south to
southeast flow will recirculate arctic air Monday, and temperatures
will remain cold with highest values near the Colorado border.
The next vigorous upper level trough near the dateline will ripple
through the flow into the western United States Tuesday and approach
the Central Plains Tuesday night. Lee troughing resulting from
increasing flow perpendicular to the Rockies will increase south
flow Monday night and Tuesday, and temperatures should rise above
freezing Tuesday. A weak front will pass through western Kansas
Tuesday night, and a stronger surge of cold air should arrive
Wednesday night. The ECMWF has a stronger trough rotating through
the Northern Plains than the GFS Wednesday night and carries a much
stronger surge of cold air into Kansas than the GFS. The blended
forecast for Thursday may be too warm, but confidence is not high
enough to justify getting too carried away with the cold air yet.
Eastward progression of the ridge and downslope flow will support
considerably warmer temperatures Friday and Saturday.
&&
.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1125 AM CST FRI DEC 20 2013
North winds at 10 to 15 knots will become light and variable this
afternoon and continue through the remainder of the taf period.
MVFR cigs at the beginning of the period are expected to dissipate
or rise into the VFR category by late afternoon. An approaching
storm system will begin impacting central and southwest Kansas
late tonight or early Saturday morning with MVFR ceilings
redeveloping. There will also be some potential for freezing
drizzle or flurries developing at Garden City and Dodge City
toward the end of the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 16 26 17 28 / 40 90 100 0
GCK 16 28 17 29 / 20 70 90 0
EHA 18 30 20 31 / 40 80 60 10
LBL 17 28 18 30 / 40 90 100 0
HYS 14 28 15 27 / 10 50 90 10
P28 21 29 19 29 / 50 100 100 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY from Midnight tonight to 6 AM CST Sunday
FOR KSZ045-046-063>066-075>081-084>090.
&&
$$
SHORT TERM...Finch
LONG TERM...Ruthi
AVIATION...Gerard
AREA FORECAST DISCUSSION
NWS WICHITA KS
1155 AM CST FRI DEC 20 2013
.UPDATE...
ISSUED AT 1153 AM CST FRI DEC 20 2013
MAIN ISSUE IS LOW CLOUDS. ONLY RUC SO FAR SEEMS TO HAVE MUCH OF A
HANDLE ON THE EXTENSIVE LOW CLOUDS. HOWEVER NOT VERY CONFIDENT IN
HOW LONG CLOUDS WILL PERSIST WEST OF I-35 WITH SOME BREAKS FINALLY
APPEARING ON VISIBLE SATELLITE OVER WESTERN KS/NORTHWEST OK.
TEMPERATURES WILL BE LIMITED TODAY WITH THE EXTENSIVE CLOUDS AND
MID SHIFT HAD THIS FAIRLY WELL IN HAND...WITH ONLY MINOR TWEAKS
TO GOING FORECAST. -HOWERTON
&&
.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 229 AM CST FRI DEC 20 2013
ARCTIC FRONT WILL CONTINUE TO PUSH THROUGH THE REMAINDER OF
SOUTHEAST KS THRU MID MORNING. LOW-LEVEL MOISTURE AND WEAK
CONVERGENCE WITHIN THE 850 BOUNDARY WILL YIELD SOME FLURRIES AND
SPOTTY LIGHT FREEZING DRIZZLE INTO MID MORNING IN SOUTH
CENTRAL/SOUTHEAST KS WHICH MAY CAUSE SOME SLICK SPOTS. THE ARCTIC
AIR IS EXPECTED TO REMAIN ENTRENCHED THROUGH THIS WEEKEND.
A VIGOROUS STORM SYSTEM OVER THE NORTHERN BAJA/DESERT SOUTHWEST
EARLY THIS MORNING...REMAINS PROGGED TO MOVE ACROSS THE SOUTHWEST
TODAY...EJECTING NORTHEASTWARD ACROSS THE SOUTHERN PLAINS AND MID
MISSISSIPPI VALLEY SATURDAY INTO SATURDAY NIGHT. THE 00Z GFS AND
ECMWF MODELS REMAIN CONSISTENTLY FURTHER NORTH WITH THE MID-LEVEL
DEFORMATION ZONE AND 850-700 RH AXIS...WHEREAS THE NAM HAS TRENDED
FURTHER SOUTH. WILL LEAN WITH A GFS/ECMWF COMPROMISE WHICH IS
CLOSE TO OUR GOING FORECAST...HOWEVER WE FEEL THERE IS STILL
ENOUGH UNCERTAINTY ON THE MID-LEVEL DEFORMATION ZONE/TROWAL
LOCATION AND ASSOCIATED PRECIPITATION TYPES TO KEEP A WINTER
STORM WATCH IN EFFECT FOR NOW.
SOME LIGHT FREEZING PRECIPITATION MAY BREAK OUT IN SOUTH
CENTRAL/SOUTHEAST KS AS SOON AS LATE TONIGHT. THE STRONGEST LIFT WITH
A PERIOD OF COUPLED FORCING ARRIVES SATURDAY AFTERNOON/EVENING
TARGETING SOUTH CENTRAL KS INTO THE FLINT HILLS. THE GFS/ECMWF BLEND
WOULD SUGGEST A SWATH OF HEAVIER SNOW ACCUMULATIONS FROM SOUTHWEST
AND SOUTH CENTRAL KS THROUGH NORTHEAST KS. LIGHT ICE ACCUMULATIONS
(0.1-0.2 INCH) WILL BE POSSIBLE IN THE SOUTH DUE TO FREEZING RAIN.
GIVEN EXPECTED MARGINAL SURFACE TEMPS (UPR 20S/LWR 30S)...THIS WOULD
PREDOMINATELY AFFECT UNTREATED ROAD SURFACES AND OVERPASSES.
IN THE WAKE OF THE STORM SYSTEM SUNDAY...ARCTIC HIGH PRESSURE ACROSS
THE CENTRAL PLAINS WILL KEEP TEMPERATURES MUCH COLDER THAN NORMAL
SUNDAY-SUNDAY NIGHT. LOWS COULD BE WELL DOWN IN THE SINGLE DIGITS
SUNDAY NIGHT ESPECIALLY WHERE THERE IS SNOWPACK.
JMC
.LONG TERM...(MONDAY THROUGH THURSDAY)
ISSUED AT 229 AM CST FRI DEC 20 2013
INITIAL UPPER TROUGH WILL SHIFT TO THE EASTERN CONUS EARLY NEXT
WEEK. FOR MID-LATE WEEK...UPPER RIDGING WILL AMPLIFY UP THE WEST
COAST INTO BRITISH COLUMBIA. THIS WILL ALLOW SHORTWAVE ENERGY TO
DIG OUT OF SOUTHWEST CANADA INTO THE NORTH CENTRAL CONUS. THIS
PATTERN FAVORS COLDER THAN AVERAGE TEMPERATURES TO CONTINUE IN OUR
AREA. EXPECTING MOST OR ALL OF THIS PERIOD TO REMAIN DRY.
JMC
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1153 AM CST FRI DEC 20 2013
VERY DIFFICULT FORECAST WITH MODELS STRUGGLING BADLY WITH LOW LEVEL
MOISTURE. DEEP LAYER LIFT IS SOMEWHAT LIMITED. GFS SUGGEST A
TRANSIENT BAND WILL MOVE ACROSS KHUT/KRSL/KSLN THIS EVENING...WITH
SECOND AREA IN THE VICINITY OF KCNU AFTER MIDNIGHT AND KICT IN THE
MORNING. THE PREDOMINATE WEATHER TYPE IS MORE LIKELY LIGHT SNOW AT
KRSL/KSLN/KHUT TONIGHT...WITH WINTRY MIX A KCNU AND SNOW/SLEET AT
KICT SAT MORNING. -HOWERTON
&&
.PRELIMINARY POINT TEMPS/POPS...
WICHITA-KICT 27 22 30 21 / 10 50 90 90
HUTCHINSON 25 20 29 19 / 10 30 90 90
NEWTON 25 21 29 19 / 10 40 90 90
ELDORADO 26 22 31 20 / 10 50 90 90
WINFIELD-KWLD 28 24 32 22 / 10 70 90 90
RUSSELL 25 14 27 17 / 10 10 60 50
GREAT BEND 25 16 28 18 / 10 20 70 60
SALINA 24 17 28 18 / 10 20 90 90
MCPHERSON 24 19 29 18 / 10 30 90 90
COFFEYVILLE 32 25 34 24 / 10 90 90 90
CHANUTE 29 24 33 23 / 10 70 90 90
IOLA 29 23 33 23 / 10 60 90 90
PARSONS-KPPF 30 24 33 24 / 10 80 90 90
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE SATURDAY NIGHT
FOR KSZ047>053-067>072-082-083-091>096-098>100.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1125 AM CST Fri Dec 20 2013
...Updated aviation discussion...
.SYNOPSIS...
ISSUED AT 340 AM CST FRI DEC 20 2013
An upper level trough was progressing southeastward into
northwestern Mexico and the southern Rockies early this morning
while a wedge of arctic air surged southward into the central
plains. Stratus covered western Kansas in the wake of the front,
with ceilings from 1000-2000 ft. Mid to high level winds were
generally out of the west-southwest over the central and southern
plains ahead of the southwestern system.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 340 AM CST FRI DEC 20 2013
The approaching winter weather will be covered in the long
term discussion since the vast majority of winter weather
is expected after 12z Saturday.
Cold high pressure will be centered over Nebraska and South Dakota
today, but the southern periphery of the high will be wedged into
southwestern Kansas. It is a tough call as to whether the low stratus
clouds will clear out, allowing temperatures to modify a little
today. The NAM and SREF indicate clearing with highs around 33F at
Dodge City, 30F at Hays and 36 at Elkhart, while the RAP holds
onto the stratus for areas east of Garden City, with much cooler
highs in upper teens to lower and mid 20s. Opted to go with an in
between solution due to the uncertainty, with mid to high 20s at
Hays, Dodge City and Pratt, and lower 30s in far southwestern and
Western Kansas. Some mid to high level cloud will be increasing
late today in advance of the aforementioned upper level trough. By
tonight, mid level cloud will continue to increase over southwestern
Kansas, with only limited radiational cooling in the brief clear
breaks. Temperatures should bottom out in the upper teens to lower
20s, but could be lower if temperatures stay colder today.
.LONG TERM...(Saturday through Thursday)
ISSUED AT 254 AM CST FRI DEC 20 2013
Models this morning remain in good agreement with an upper level
trough/low lifting northeast from west central Texas into western
Oklahoma on Saturday. Widespread steady precipitation is expected
by the early Saturday morning across southwest and south central
Kansas given the moisture, warm air advection, and improving
frontogenesis ahead of the approaching upper level system. The
warm air advection early Saturday will result in a wintry mix
early Saturday, however the NAM, GFS, and ECMWF still disagree
with the magnitude of warm layer aloft. At this time confidence is
low on which model may be more correct so have decided to lean
towards a compromise between the warmer GFS and the cooler NAM and
ECMWF. Based on this as a first guess and applying the top down
approach it still appears that there will be an extended period of
sleet and freezing rain across much of south central Kansas early
Saturday morning. The area more favorable for ice accumulations
currently appears to be southeast of a Stafford to Greensburg to
Ashland line. Further northwest a brief period of freezing
precipitation will be possible early Saturday, however this should
quickly change over to snow during the early morning hours.
By Saturday afternoon the atmosphere will cool enough for mainly
snow and an area of 850-700mb frontogenesis will begin to improve
across southwest Kansas. The 00z Friday model runs continue to
indicated some discrepancies with where this area of forcing will
develop, however they all agree that as frontogenesis improves the
snow will become steadier and heavier at times Saturday afternoon
and early Saturday night. Both the GFS and ECMWF continues to
highlight this area of frontogenesis will be developing near a
line from roughly Hugoton to near Dodge City to around LaCrosse.
00z NAM was further southeast. At this time given the agreement
between the GFS and ECMWF and the run to run consistency on
location of this frontogenesis have decided to stay close to the
00z GFS/ECMWF. The steadiest and heaviest snowfall appears to
occur from 18z to 06z as the forcing along the mid level
baroclinic zone strengths and remains nearly stationary. After 06z
this baroclinic zone will begin to slide east towards central
Kansas as the upper trough moves across southeast Kansas and into
Missouri. Snow accumulations of 2 to near 6 inches still appears
reasonable. Locally higher accumulations are not out of the
question from Dodge City northeast where the snow is expected to
begin sooner and the mid level forcing appears to last slightly
longer. Given that there still is some uncertainty on location and
snowfall amounts late Saturday and Saturday night have decided to
continue with the Winter Storm Watch and not upgrade to a warning
or advisory just yet.
On Sunday a weaker upper level disturbance will cross western
Kansas. Although snow is not anticipated with this next weaker
system, increasing clouds may aid in keeping temperatures down
Sunday afternoon. Based on possible cloud cover and expected
snowfall on Sunday will continue to favor the cooler MAV/MOSGUIDE
for highs given expected snow cover.
On Sunday night an area of high pressure at the surface will
start to build into Kansas from the north. As the surface ridge
axis moves into portions of western Kansas the winds will become
light and variable. Light winds and snow cover will provided
favorable conditions for temperatures to fall back to near zero
given a period of clear skies. At this time however am somewhat
concerned about some increasing clouds after midnight. As a result
will trim temperatures back into the single digits which are
cooler latest guidance.
A gradual warming trend will then begin to develop early next
week as a northwest flow backs and becomes more perpendicular to
the Rockies. How quickly temperatures will rebound early next week
is still somewhat unclear, but the latest temperature trend
currently in the forecast still appears to be on track. A cold
front crossing western Kansas mid week will end this warming trend
briefly.
&&
.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
ISSUED AT 1125 AM CST FRI DEC 20 2013
North winds at 10 to 15 knots will become light and variable this
afternoon and continue through the remainder of the taf period.
MVFR cigs at the beginning of the period are expected to dissipate
or rise into the VFR category by late afternoon. An approaching
storm system will begin impacting central and southwest Kansas
late tonight or early Saturday morning with MVFR ceilings
redeveloping. There will also be some potential for freezing
drizzle or flurries developing at Garden City and Dodge City
toward the end of the period.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 23 20 26 17 / 10 50 100 100
GCK 24 19 27 17 / 10 30 90 90
EHA 28 21 30 20 / 10 40 80 60
LBL 25 20 28 18 / 10 50 100 100
HYS 21 19 28 15 / 0 20 80 90
P28 25 23 28 19 / 10 70 100 100
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from late tonight through late Saturday night
FOR KSZ064>066-076>081-085>090.
&&
$$
SYNOPSIS...Finch
SHORT TERM...Finch
LONG TERM...Burgert
AVIATION...Gerard
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
513 AM CST Fri Dec 20 2013
...Updated aviation discussion...
.SYNOPSIS...
ISSUED AT 340 AM CST FRI DEC 20 2013
An upper level trough was progressing southeastward into
northwestern Mexico and the southern Rockies early this morning
while a wedge of arctic air surged southward into the central
plains. Stratus covered western Kansas in the wake of the front,
with ceilings from 1000-2000 ft. Mid to high level winds were
generally out of the west-southwest over the central and southern
plains ahead of the southwestern system.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 340 AM CST FRI DEC 20 2013
The approaching winter weather will be covered in the long
term discussion since the vast majority of winter weather
is expected after 12z Saturday.
Cold high pressure will be centered over Nebraska and South Dakota
today, but the southern periphery of the high will be wedged into
southwestern Kansas. It is a tough call as to whether the low stratus
clouds will clear out, allowing temperatures to modify a little
today. The NAM and SREF indicate clearing with highs around 33F at
Dodge City, 30F at Hays and 36 at Elkhart, while the RAP holds
onto the stratus for areas east of Garden City, with much cooler
highs in upper teens to lower and mid 20s. Opted to go with an in
between solution due to the uncertainty, with mid to high 20s at
Hays, Dodge City and Pratt, and lower 30s in far southwestern and
Western Kansas. Some mid to high level cloud will be increasing
late today in advance of the aforementioned upper level trough. By
tonight, mid level cloud will continue to increase over southwestern
Kansas, with only limited radiational cooling in the brief clear
breaks. Temperatures should bottom out in the upper teens to lower
20s, but could be lower if temperatures stay colder today.
.LONG TERM...(Saturday through Thursday)
ISSUED AT 254 AM CST FRI DEC 20 2013
Models this morning remain in good agreement with an upper level
trough/low lifting northeast from west central Texas into western
Oklahoma on Saturday. Widespread steady precipitation is expected
by the early Saturday morning across southwest and south central
Kansas given the moisture, warm air advection, and improving
frontogenesis ahead of the approaching upper level system. The
warm air advection early Saturday will result in a wintry mix
early Saturday, however the NAM, GFS, and ECMWF still disagree
with the magnitude of warm layer aloft. At this time confidence is
low on which model may be more correct so have decided to lean
towards a compromise between the warmer GFS and the cooler NAM and
ECMWF. Based on this as a first guess and applying the top down
approach it still appears that there will be an extended period of
sleet and freezing rain across much of south central Kansas early
Saturday morning. The area more favorable for ice accumulations
currently appears to be southeast of a Stafford to Greensburg to
Ashland line. Further northwest a brief period of freezing
precipitation will be possible early Saturday, however this should
quickly change over to snow during the early morning hours.
By Saturday afternoon the atmosphere will cool enough for mainly
snow and an area of 850-700mb frontogenesis will begin to improve
across southwest Kansas. The 00z Friday model runs continue to
indicated some discrepancies with where this area of forcing will
develop, however they all agree that as frontogenesis improves the
snow will become steadier and heavier at times Saturday afternoon
and early Saturday night. Both the GFS and ECMWF continues to
highlight this area of frontogenesis will be developing near a
line from roughly Hugoton to near Dodge City to around LaCrosse.
00z NAM was further southeast. At this time given the agreement
between the GFS and ECMWF and the run to run consistency on
location of this frontogenesis have decided to stay close to the
00z GFS/ECMWF. The steadiest and heaviest snowfall appears to
occur from 18z to 06z as the forcing along the mid level
baroclinic zone strengths and remains nearly stationary. After 06z
this baroclinic zone will begin to slide east towards central
Kansas as the upper trough moves across southeast Kansas and into
Missouri. Snow accumulations of 2 to near 6 inches still appears
reasonable. Locally higher accumulations are not out of the
question from Dodge City northeast where the snow is expected to
begin sooner and the mid level forcing appears to last slightly
longer. Given that there still is some uncertainty on location and
snowfall amounts late Saturday and Saturday night have decided to
continue with the Winter Storm Watch and not upgrade to a warning
or advisory just yet.
On Sunday a weaker upper level disturbance will cross western
Kansas. Although snow is not anticipated with this next weaker
system, increasing clouds may aid in keeping temperatures down
Sunday afternoon. Based on possible cloud cover and expected
snowfall on Sunday will continue to favor the cooler MAV/MOSGUIDE
for highs given expected snow cover.
On Sunday night an area of high pressure at the surface will
start to build into Kansas from the north. As the surface ridge
axis moves into portions of western Kansas the winds will become
light and variable. Light winds and snow cover will provided
favorable conditions for temperatures to fall back to near zero
given a period of clear skies. At this time however am somewhat
concerned about some increasing clouds after midnight. As a result
will trim temperatures back into the single digits which are
cooler latest guidance.
A gradual warming trend will then begin to develop early next
week as a northwest flow backs and becomes more perpendicular to
the Rockies. How quickly temperatures will rebound early next week
is still somewhat unclear, but the latest temperature trend
currently in the forecast still appears to be on track. A cold
front crossing western Kansas mid week will end this warming trend
briefly.
&&
.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
ISSUED AT 511 AM CST FRI DEC 20 2013
Gusty north winds will decrease into the 10 to 15 knot range by
the early afternoon as an area of high pressure at the surface
builds into the central plains. Towards 00z Saturday these
north/northeast winds will begin to gradually veer to the
southeast as the surface ridge axis moves across central Kansas.
06z NAM BUFR soundings and latest HRRR both suggest that the MVFR
cigs will gradually erode between 15z and 18z and give way to vfr
cigs. Will reintroduce decreasing cigs after midnight as warm air
advection improves.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 27 20 26 19 / 10 50 100 100
GCK 28 19 27 19 / 10 30 90 90
EHA 32 21 30 22 / 10 40 80 60
LBL 30 20 28 21 / 10 50 100 100
HYS 26 19 28 17 / 0 20 80 90
P28 29 23 28 21 / 10 70 100 100
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from late tonight through late Saturday night
FOR KSZ064>066-076>081-085>090.
&&
$$
SYNOPSIS...Finch
SHORT TERM...Finch
LONG TERM...Burgert
AVIATION...Burgert
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
357 AM CST Fri Dec 20 2013
...Updated for synopsis and short term discussion...
.SYNOPSIS...
ISSUED AT 340 AM CST FRI DEC 20 2013
An upper level trough was progressing southeastward into
northwestern Mexico and the southern Rockies early this morning
while a wedge of arctic air surged southward into the central
plains. Stratus covered western Kansas in the wake of the front,
with ceilings from 1000-2000 ft. Mid to high level winds were
generally out of the west-southwest over the central and southern
plains ahead of the southwestern system.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 340 AM CST FRI DEC 20 2013
The approaching winter weather will be covered in the long
term discussion since the vast majority of winter weather
is expected after 12z Saturday.
Cold high pressure will be centered over Nebraska and South Dakota
today, but the southern periphery of the high will be wedged into
southwestern Kansas. It is a tough call as to whether the low stratus
clouds will clear out, allowing temperatures to modify a little
today. The NAM and SREF indicate clearing with highs around 33F at
Dodge City, 30F at Hays and 36 at Elkhart, while the RAP holds
onto the stratus for areas east of Garden City, with much cooler
highs in upper teens to lower and mid 20s. Opted to go with an in
between solution due to the uncertainty, with mid to high 20s at
Hays, Dodge City and Pratt, and lower 30s in far southwestern and
Western Kansas. Some mid to high level cloud will be increasing
late today in advance of the aforementioned upper level trough. By
tonight, mid level cloud will continue to increase over southwestern
Kansas, with only limited radiational cooling in the brief clear
breaks. Temperatures should bottom out in the upper teens to lower
20s, but could be lower if temperatures stay colder today.
.LONG TERM...(Saturday through Thursday)
ISSUED AT 254 AM CST FRI DEC 20 2013
Models this morning remain in good agreement with an upper level
trough/low lifting northeast from west central Texas into western
Oklahoma on Saturday. Widespread steady precipitation is expected
by the early Saturday morning across southwest and south central
Kansas given the moisture, warm air advection, and improving
frontogenesis ahead of the approaching upper level system. The
warm air advection early Saturday will result in a wintry mix
early Saturday, however the NAM, GFS, and ECMWF still disagree
with the magnitude of warm layer aloft. At this time confidence is
low on which model may be more correct so have decided to lean
towards a compromise between the warmer GFS and the cooler NAM and
ECMWF. Based on this as a first guess and applying the top down
approach it still appears that there will be an extended period of
sleet and freezing rain across much of south central Kansas early
Saturday morning. The area more favorable for ice accumulations
currently appears to be southeast of a Stafford to Greensburg to
Ashland line. Further northwest a brief period of freezing
precipitation will be possible early Saturday, however this should
quickly change over to snow during the early morning hours.
By Saturday afternoon the atmosphere will cool enough for mainly
snow and an area of 850-700mb frontogenesis will begin to improve
across southwest Kansas. The 00z Friday model runs continue to
indicated some discrepancies with where this area of forcing will
develop, however they all agree that as frontogenesis improves the
snow will become steadier and heavier at times Saturday afternoon
and early Saturday night. Both the GFS and ECMWF continues to
highlight this area of frontogenesis will be developing near a
line from roughly Hugoton to near Dodge City to around LaCrosse.
00z NAM was further southeast. At this time given the agreement
between the GFS and ECMWF and the run to run consistency on
location of this frontogenesis have decided to stay close to the
00z GFS/ECMWF. The steadiest and heaviest snowfall appears to
occur from 18z to 06z as the forcing along the mid level
baroclinic zone strengths and remains nearly stationary. After 06z
this baroclinic zone will begin to slide east towards central
Kansas as the upper trough moves across southeast Kansas and into
Missouri. Snow accumulations of 2 to near 6 inches still appears
reasonable. Locally higher accumulations are not out of the
question from Dodge City northeast where the snow is expected to
begin sooner and the mid level forcing appears to last slightly
longer. Given that there still is some uncertainty on location and
snowfall amounts late Saturday and Saturday night have decided to
continue with the Winter Storm Watch and not upgrade to a warning
or advisory just yet.
On Sunday a weaker upper level disturbance will cross western
Kansas. Although snow is not anticipated with this next weaker
system, increasing clouds may aid in keeping temperatures down
Sunday afternoon. Based on possible cloud cover and expected
snowfall on Sunday will continue to favor the cooler MAV/MOSGUIDE
for highs given expected snow cover.
On Sunday night an area of high pressure at the surface will
start to build into Kansas from the north. As the surface ridge
axis moves into portions of western Kansas the winds will become
light and variable. Light winds and snow cover will provided
favorable conditions for temperatures to fall back to near zero
given a period of clear skies. At this time however am somewhat
concerned about some increasing clouds after midnight. As a result
will trim temperatures back into the single digits which are
cooler latest guidance.
A gradual warming trend will then begin to develop early next
week as a northwest flow backs and becomes more perpendicular to
the Rockies. How quickly temperatures will rebound early next week
is still somewhat unclear, but the latest temperature trend
currently in the forecast still appears to be on track. A cold
front crossing western Kansas mid week will end this warming trend
briefly.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
ISSUED AT 1159 PM CST THU DEC 19 2013
IFR/MVFR CIGS will persist in the wake of an arctic front through
18z and then gradually clear between 21 and 02z. Winds will
gradaually become light east to southeasterly after 21z as surface
pressures fall in the lee of the Rockies.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 27 20 26 19 / 10 50 80 80
GCK 28 19 27 19 / 10 30 70 70
EHA 32 21 30 22 / 10 40 70 60
LBL 30 20 28 21 / 10 50 80 80
HYS 26 19 28 17 / 0 20 70 70
P28 29 23 28 21 / 10 70 80 80
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH from late tonight through late Saturday night
FOR KSZ064>066-076>081-085>090.
&&
$$
SYNOPSIS...Finch
SHORT TERM...Finch
LONG TERM...Burgert
AVIATION...Finch
THE EXTENDED FORECAST DISCUSSION BEGINS ON MONDAY WITH A DEEP 300MB
TROUGH OVER THE EASTERN CONUS AS A STRONG MAJOR SHORT WAVE TROUGH
EXITS TO THE EAST. A 150 KNOT JET STREAK WILL CARRY THE STRONG SHORT
WAVE OFF TO THE EAST AND NORTHEAST...BUT...WILL LEAVE A BROAD DEEP
TROUGH CENTERED OVER THE WESTERN GREAT LAKES REGION AS ANOTHER WEAK
VORT MAX WILL SWING THROUGH THE BASE OF THE TROUGH AS THE FRONT
EXITS. THIS...WITH SOME RESIDUAL LOW LEVEL MOISTURE REMAINING BEHIND
THE FRONT...SOME SHOWER ACTIVITY WILL BE POSSIBLE. BUT WITH A SMALL
DRY LAYER AT THE SURFACE...THIS PRECIP CHANCE MAY BE HINDERED. THE
EURO HAS REMAINED A BIT CONSISTENT WITH THIS...WHERE THE NAM AND GFS
HAS ALL OF A SUDDEN SHOWN QUITE A BIT OF MOISTURE...BUT WITH IT
BEING SHALLOW AND WITH THE DRY LAYER AT THE SURFACE...WILL MAINLY GO
WITH THE GRIDS INHERITED AND LEAVE SLIGHT CHANCE SHOWERS IN THE
FORECAST FOR MONDAY.
FOR THE REST OF THE EXTENDED...THE UPPER LEVEL PATTERN WILL REMAIN
QUITE ACTIVE AND PROGRESSIVE WITH A GENERAL TROUGH OVER THE
NORTHEAST WITH NUMEROUS SHORT WAVES DIVING SOUTHEAST FROM CENTRAL
CANADA INTO THE GREAT LAKES AND OHIO VALLEY. THE FIRST WAVE WILL
MOVE THROUGH WEDNESDAY NIGHT AND THE SECOND THURSDAY NIGHT. BOTH OF
THESE WAVES ARE IN DRY NORTHWEST FLOW AND HAVE LITTLE MOISTURE TO
WORK WITH AND ALSO HAVE THE BULK OF THE LIFT TO THE NORTH. SO WITH
THIS IN MIND...HAVE LITTLE REASON TO GO MORE THAN SLIGHT CHANCE AND
HAVE GONE BELOW THE ALL MODEL BLEND WITH POPS. THIS IS AGREED UPON
BY SURROUNDING OFFICES AS WELL. WITH A NORTHWEST FLOW AND NO
SIGNIFICANT SHOTS OF COOLER AIR EXPECTED...SOME SNOW SHOWERS WILL BE
IN THE FORECAST BUT ONLY DURING WEDNESDAY NIGHT AND THURSDAY
NIGHT...THEN CHANGING BACK TO RAIN DURING THE DAY.
CONCERNING TEMPERATURES...BY MONDAY NIGHT...THE POTENT SHORT WAVE
LIFTS OFF TO THE NORTHEAST AS IN THE LOWER LEVELS...NORTHWEST FLOW
SETS UP AS THE BULK OF THE COLDER CANADIAN AIR MASS FINALLY ADVECTS
INTO THE OHIO VALLEY FOR TUESDAYS TEMPS AS THEY WILL FALL THROUGH
THE DAY MONDAY AND INTO MONDAY NIGHT LEAVING HIGH TEMPS BARELY
GETTING OUTTA THE 20S FOR TUESDAY. AFTERWARD...TEMPS WILL MODERATE A
BIT AS THESE WAVES WILL NOT PROVIDE MUCH ADVECTION OF AIR AND TEMP
TRENDS WILL REMAIN DIURNAL. HIGHS AND LOWS FOR THE REST OF THE
EXTENDED WILL BE WITHIN A FEW DEGREES OF NORMAL FOR THIS TIME OF
YEAR.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 638 PM EST SAT DEC 21 2013
WINDS HAVE BACKED OFF AT THE SURFACE WITH THE RAIN SHOWER ACTIVITY
OVER THE PAST FEW HOURS. THIS WILL ALLOW FOR A PERIOD OF PRE-FRONTAL LOW
LEVEL WIND SHEAR THIS EVENING. AS THE COLD FRONT MARCHES EAST...WINDS
WILL INCREASE AGAIN...BUT GIVEN THE 60 KNOTS OF WINDS AT 3KFT...STILL
LIKELY TO HAVE SOME LLWS CONDITIONS OFF THE SURFACE DESPITE SOME 20
T0 25 KNOT GUST. THUS...WILL CONTINUE TO CARRY LLWS UNTIL THE FRONT
ARRIVES LATE TONIGHT. THE FRONT SHOULD PUSH INTO SOUTH CENTRAL
KENTUCKY BY 06Z TONIGHT...WITH THE THREAT FOR SOME SEVERE
THUNDERSTORM WIND GUSTS WITH THE ONSET OF PRECIPITATION. FOR
NOW...WILL STAY ON THE STRONG SIDE WITH THE WIND GUST...BUT A STRAY
SEVERE GUST OF 50+ KNOTS WILL BE POSSIBLE LATE TONIGHT. CEILINGS ARE
EXPECTED TO REMAIN AT OR ABOVE 4KFT WITH THE FRONTAL
PASSAGE...EVENTUALLY LOWERING TO MVFR AS THE FRONT MARCHES EAST
TOMORROW MORNING. RAIN WILL GRADUALLY WIND DOWN DURING THE
MORNING...AND COME TO AN END BY MIDDAY. CIGS MAY RECOVER IN THE
AFTERNOON...BUT MAY NOT GET OUT OF THE MVFR RANGE.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 7 AM EST SUNDAY FOR KYZ044-050>052-058>060-
068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...KAS
SHORT TERM...GEOGERIAN
LONG TERM...SHALLENBERGER
AVIATION...KAS
AREA FORECAST DISCUSSION
NWS PADUCAH KY
239 PM CST Fri Dec 20 2013
.SHORT TERM...(This Evening through Sunday)
ISSUED AT 238 PM CST FRI DEC 20 2013
Flood Watch will continue as is tonight through Saturday night.
Still looking at 2-4+ inches area wide, slightly higher amounts
to 5 inches possible near and just NW of the Ohio River. Front
will enter the area tonight and stall near the Ohio River. Rain
and storms forecast to increase tonight especially after midnight,
continuing through Saturday.
Could see a few strong to severe storms Saturday late day and
evening as wind fields increase substantially with some surface
based instability along and south of the boundary, especially
across west Kentucky. Isolated damaging wind gusts and a brief
short lived tornado or two cannot be ruled out. The activity
should quickly push to the east after midnight Saturday as we
dry slot. Mid level drying will be pronounced, but low level
moisture will linger with SW flow aloft. May be some drizzle into
Sunday but that`s about it, as temperatures fall through the day.
In terms of temps, dew points and winds with the front coming into
the area tonight and Saturday, used a blend of RAP 13km data and
short term 3 hourly GFS/NAM data.
.LONG TERM...(Sunday Night through Friday)
ISSUED AT 238 PM CST FRI DEC 20 2013
In the wake of the weekend storm...colder and drier air will arrive
for early next week. Model soundings depict some lingering moisture
Sunday night until the passage of the 850 mb trough axis. This could
translate into some flurries or drizzle...but no measurable precip
is indicated in the 12z gfs/nam/ecmwf model qpf. By Monday
night...mainly clear skies are expected.
Monday night...the combination of clear skies and decreasing winds
should allow temps to radiate nicely. Will lower Monday night
lows closer to gfs and ecmwf mos...both of which range from 10 to 15
degrees across most of the area.
Tuesday will be another cold day...but there is about a 10 degree
difference between ecmwf and gfs mos highs. The 00z ecmwf is more
progressive with the eastward motion of the thermal trough...while
the 12z gfs lingers the cold air through the day. Will split the
difference between them...which yields highs in the upper 20s to
lower 30s despite sunny skies.
The models depict a 500 mb longwave trough axis setting up over the
Mississippi Valley Christmas Day into Thursday. Shortwaves rotating
through the trough will bring at least some cloudiness...if not
measurable light precip. Model soundings have trended drier during
this time period...and the 12z gfs and gfs ensemble mean show zero
qpf. The 12z ecmwf indicates some patchy light precip. Will follow
the model trends and lower pops into the slight chance category for
Christmas night and Thursday. Precip type would be mainly snow until
boundary layer temps become marginal for snow Thursday
afternoon.
In the wake of the departing longwave trough...another shot of cold
air is expected for Friday. As would be expected seven days
out...there is fair to poor agreement on how cold it will get.
Forecast will represent a blend of gfs/ecmwf temps.
&&
.AVIATION...
ISSUED AT 1123 AM CST FRI DEC 20 2013
Low end MVFR cigs to persist through the afternoon with gusty SSW
winds in the 10-20kt range. Will carry VCSH for now given limited
activity seen radar. Activity should increase tonight, especially
from 03 UTC on. Brought the front through KCGI, but held for now
on KPAH/KEVV and KOWB. Went prevailing SHRA overnight with VCTS as
instability supportive of TSRA develops. The cold front entering
into the region should reach to about the Ohio River and then
stall, maybe lift slightly back to the north Saturday morning.
&&
.PAH WATCHES/WARNINGS/ADVISORIES...
IL...FLOOD WATCH from 6 PM CST this evening through late Saturday
night FOR ILZ075>078-080>094.
MO...FLOOD WATCH from 6 PM CST this evening through late Saturday
night FOR MOZ076-086-087-100-107>112-114.
IN...FLOOD WATCH from 6 PM CST this evening through late Saturday
night FOR INZ081-082-085>088.
KY...FLOOD WATCH from 6 PM CST this evening through late Saturday
night FOR KYZ001>022.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
717 PM EST SAT DEC 21 2013
.SYNOPSIS...
A STRONG COLD FRONT ACCOMPANIED BY GUSTY WINDS PASSES SUNDAY.
AREA RIVERS WILL BE ON THE RISE THROUGH MONDAY. AN UPPER LEVEL
DISTURBANCE BRINGS SNOW SHOWERS MONDAY NIGHT INTO TUESDAY. MUCH
CALMER WEATHER IS EXPECTED THROUGH THE REST OF THE HOLIDAY WEEK
WITH BELOW NORMAL TEMPERATURES.
&&
.NEAR TERM /THROUGH SUNDAY/...
THE LOW PRESSURE SYSTEM OVER THE CENTRAL PLAINS WILL CONTINUE TO
LIFT NORTH AND EASTWARD...HELPING TO SHIFT THE NEARLY STATIONARY
FRONT NORTHWARD TONIGHT. THIS WILL GIVE US A BRIEF DRY
PERIOD...OR A PERIOD WITH MORE SCATTERED SHOWERS THAN SOLID RAIN
UNTIL PRECIPITATION WITH THE COLD FRONT APPROACHES. FOR NOW...ONLY
MADE A FEW ADJUSTMENTS TO THE POPS BASED OFF OF THE CURRENT RADAR
TRENDS...WITH THE HEAVIER RAIN LIFTING NORTHWARD ALREADY. WITH THE
SOUTHERLY FLOW CONTINUING AND A BREAK IN THE RAIN...TEMPERATURES
MAY ACTUALLY CONTINUE TO WARM OVERNIGHT WITH 850HPA TEMPERATURES
APPROACHING +14 TO +15C.
AS THE LOW CONTINUES TO LIFT TOWARDS THE GREAT LAKES...IT WILL
FINALLY HELP TO PUSH THE COLD FRONT TOWARDS AND ACROSS THE REGION
BY SUNDAY AFTERNOON. RAIN AHEAD OF THE FRONT SHOULD APPROACH THE
REGION OVERNIGHT. MANY OF THE HI RES MODELS SUGGEST THAT A
CONVECTIVE LINE COULD DEVELOP...BUT CONSIDERING THE TIME OF NIGHT
AND THE THERMODYNAMICS...NOT OVERLY CONVINCED THERE WILL BE MUCH
THUNDER...EXCEPT IN OUR EXTREME WESTERN ZONES. SO FOR
NOW...CONTINUED TO LEAVE OUT ANY THUNDER MENTION. A STRENGTHENING
PRESSURE GRADIENT AND STRONG WINDS AT LOW LEVELS COULD BE BROUGHT
DOWN WITH MOMENTUM TRANSFER WITH THE LINE. BUT THIS LOOKS TO BE NO
MORE THAN AROUND 40MPH. THE HRRR AGREES WITH THIS BASED ON 10M WIND
GUST FIELD.
CONTINUED THE FLOOD WATCH TONIGHT DESPITE THE BREAK IN PRECIP
ANTICIPATED. WITH MANY CREEKS AND RIVERS ALREADY SWOLLEN FROM THE
ONGOING RAINFALL AND ADDITIONAL RAINFALL EXPECTED WITH THE
FRONT...SOME FLOODING IS STILL A POSSIBILITY...ESPECIALLY IN LOW
LYING AREAS THAT ARE ALREADY SATURATED.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
COLD FRONT WILL BE EAST OF OUR AREA SUNDAY NIGHT AS ANY QPF LEFT
OVER ASSOCIATED WITH BAROCLINIC ZONE WILL AFFECT NRN WV MTNS AND
WRN MD UNTIL MID EVENING. A BRIEF PERIOD OF CLEARING MON EVENING
BEFORE CLOUDS ASSOCIATED WITH THE SURGE OF COLD AIR AND LOWER MID
LVL HEIGHTS ARRIVE FROM THE WEST.
MID LVL TROUGH SWEEPS THROUGH MON NGT - TUE. THIS IS ACCOMPANIED
BY MUCH COLDER AIR AS H8 TEMPS PLUMMET BACK INTO THE NEGATIVE MID
TEENS BY 12Z TUES. SCATTERED SNOW SHOWERS AND LAKE EFFECT SNOW
SHOWERS ARE PREDICTED MON NGT INTO TUES EVENING. WIND TRAJECTORY
IS NOT FAVORABLE FOR SIGNIFICANT SNOW ACCUMULATIONS. OUTSIDE THE
SNOW BELT OF NWRN PA...LOOK FOR MINOR ACCUMS AT BEST GIVEN SHORT
DURATION AND LACK OF FAVORABLE SNOW DYNAMICS AS NEEDED UPPER LEVEL
TEMPERATURES ARE BELOW REGION OF UPWARD VERTICAL MOTION.
ANTICYCLONIC FLOW RAPIDLY ENSUES DURING THE PREDAWN HOURS WEDNESDAY.
THIS WILL SHUT OFF THE LAKE EFFECT MACHINE AS SCOUR OUT CLOUDS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
FOCUSED EFFORTS ON NEAR AND SHORT TERM TODAY...LATEST NUMERICAL
MODELS REMAIN CONSISTENT WITH WEATHER PATTER OVER THE LONG RANGE.
BELOW NORMAL TEMPS ARE PROJECTED FOR MUCH OF THE EXTENDED.
PREVIOUS DISCUSSION FOLLOWS:
BLDG HIGH PRES SHOULD END ANY SNOW SHWRS TUE EVE...WITH DRY WEATHER
CONTG WED. A WK CLIPPER IS PROGGED FOR THU...THOUGH TIMING AND
STRENGTH DIFFERENCES IN THE MDLS PRECLUDE MORE THAN A SLGT CHC
MENTION FOR SNOW SHWRS ATTM. BLDG HIGH PRES IS EXPD AGAIN BY THE
END OF THE WK. OVERALL...TEMPS SHOULD AVG BLO SEASONAL LVLS THRU
THE PD.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
MEDIUM CONFIDENCE FORECAST.
VFR WEATHER WILL CONTINUE FOR MUCH OF THE NIGHT SAVE FOR FKL WHERE
THEY SHOULD STAY WITH IFR/MVFR AS REGION RESIDES IN WARM SECTOR.
VCSH WAS INCLUDED IN ALL TERMINALS AS SCATTERED SHOWERS CONTINUE
TO ADVECT IN FROM THE SE.
A BRIEF PERIOD OF GUSTY WINDS AND REDUCED VISIBILITY WILL OCCUR
BEFORE DAYBREAK RESULTING FROM A LINE OF SHOWERS ALONG THE
LEADING EDGE OF THE FRONT. FOR NOW...USED THE FOLLOWING
TIMING...8Z ZZV...9Z OHIO RIVER...11Z-12Z DUJ-LBE. COULD EASILY
SEE A SHORT DURATION OF IFR WITH THIS ACTIVITY...BUT TOO SMALL
TEMPORAL DURATION FOR INCLUSION AT THIS JUNCTURE. MVFR
RESTRICTIONS WILL CONTINUE FOR MUCH OF SUN MRNG BEFORE CIGS LIFT
TO VFR BY AFTN. WINDS WILL BE GUSTY THROUGH THE PERIOD WITH GUSTS
AROUND 25KTS THROUGH SUN AFTN AT MOST AIRPORTS.
AREAS WITH MOST UNCERTAINTY...
- FKL COULD LIFT TO MVFR FOR A FEW HOURS THIS EVENING
- VIS/CIGS LIKELY WILL BE LOWER THAN FORECAST FOR A SHORT PERIOD
WITH ONSET OF PCPN ASSOCIATED WITH COLD FRONT
- COULD SEE VFR DEVELOP FASTER THAN CURRENTLY FORECAST...ESPECIALLY
ALONG AND S OF I-70
WINDS ARE STRONG /45-50KTS/ IN LOW LEVELS WITH LLWS A POTENTIAL
HAZARD ESPECIALLY AT VALLEY LOCATIONS.
.OUTLOOK.../00Z MONDAY THROUGH THURSDAY/...
CONTINUED IFR RESTRICTIONS WILL BE POSSIBLE MONDAY NIGHT THROUGH
TUESDAY NORTH OF INTERSTATE 80 DUE TO LAKE EFFECT SNOW SHOWERS.
OTHERWISE...NO OTHER WIDESPREAD WEATHER RELATED AVIATION HAZARDS
EXISTS.
&&
.HYDROLOGY...
A FLOOD WARNING IS IN EFFECT FOR WILLS CREEK AT CAMBRIDGE
AFFECTING GUERNSEY COUNTY AND THE MUSKINGUM RIVER AT COSHOCTON
AFFECTING COSHOCTON COUNTY. RAINFALL AMOUNTS OF 1.00 TO NEARLY
3.00 INCHES OF RAINFALL ARE EXPECTED OVER THE TUSCARAWAS RIVER AND
MUSKINGUM RIVER BASINS.
SHARP RISES ARE EXPECTED ON RIVERS AND STREAMS ACROSS EASTERN OHIO.
THESE RISES WILL BE SUFFICIENT FOR THE MUSKINGUM RIVER AT COSHOCTON
TO RISE ABOVE FLOOD STAGE SUNDAY AFTERNOON. WILLS CREEK WILL RISE
ABOVE FLOOD STAGE SUNDAY EVENING. MINOR FLOODING IS EXPECTED AT BOTH
LOCATIONS.
A FLOOD ADVISORY IS IN EFFECT FOR THE OHIO RIVER AT THE POINT IN
PITTSBURGH. THE OHIO RIVER IS EXPECTED TO RISE ABOVE 18.0 FEET AND
BEGIN TO FLOOD THE MONONGAHELA RIVER PARKING WHARF SUNDAY AFTERNOON.
THE OHIO RIVER THE CREST IS EXPECTED MONDAY AFTERNOON AT 21.8 FEET.
THIS WILL COMPLETELY FLOOD THE MONONGAHELA PARKING WHARF. AT THIS
TIME FLOOD WATERS ARE NOT EXPECTED TO AFFECT THE 10TH STREET
BYPASS. STRONG RISES ON THE OHIO RIVER ARE FORECAST SUNDAY WITH
CONTINUED ELEVATED LEVELS THROUGH TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR OHZ039>041-048-057.
PA...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR PAZ007>009-013.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
608 PM EST SAT DEC 21 2013
.SYNOPSIS...
A STRONG COLD FRONT ACCOMPANIED BY GUSTY WINDS PASSES SUNDAY.
AREA RIVERS WILL BE ON THE RISE THROUGH MONDAY. AN UPPER LEVEL
DISTURBANCE BRINGS SNOW SHOWERS MONDAY NIGHT INTO TUESDAY. MUCH
CALMER WEATHER THE BALANCE OF THE HOLIDAY WEEK WITH BELOW NORMAL
TEMPERATURES.
&&
.NEAR TERM /THROUGH SUNDAY/...
SOUTHERLY FLOW CONTINUES TO INCREASE AHEAD OF DEEPENING SFC CYCLONE
WHICH IS EVIDENT BY VIEWING REGIONAL RADAR MOSAIC AS PLUME OF RAIN
CONTINUES TO SHIFT NNE. DRY WEATHER HAS ALREADY REACHED NRN WV AND
WRN MD AND WILL CONTINUE TO OVERSPREAD MUCH OF THE CWA THIS
EVENING. PARTIAL CLEARING OVER THE NORTHERN WV MOUNTAINS HAS
ALLOWED TEMPS TO SOAR INTO THE MID 70S. THIS AIR WILL MAKE IT TO
THE MASON DIXON LINE...WHILE 60S SHALL ENCOMPASS WRN PA AND THE
NRN WV PANHANDLE. TEMPS WILL NOT FALL MUCH TONIGHT AS BOUNDARY
LAYER REMAINS WELL MIXED.
COLD FRONT CROSSES SUNDAY MORNING INTO EARLY AFTERNOON. BAND OF
MODERATE TO HEAVY SHOWERS WILL BE OUT AHEAD OF IT. THERMODYNAMIC
PARAMETERS STILL ARE NOT OVERLY IMPRESSIVE DUE TO THE TIME OF DAY
IT CROSSES. UPPER LEVEL DYNAMICS DO NOT WOW ME EITHER AS STRONG
AGEOSTROPHIC FORCING RESULTING FROM JET COUPLING IS NOT PRESENT.
CONTINUED TO OMIT THUNDER FROM FCST...DESPITE SPC BRINGING SLIGHT
RISK TO NRN WV PANHANDLE. GUSTY WINDS UPWARDS OF 40 MPH MAY OCCUR BASED
ON MOMENTUM TRANSFER. THIS COULD KNOCK AROUND OUTDOOR CHRISTMAS
DECORATIONS. HRRR AGREES WITH THIS BASED ON 10M WIND GUST FIELD.
HEAVY RAIN REMAINS A CONCERN ACROSS THE FLOOD WATCH AREA. AT THIS
TIME...ADDITIONAL AMOUNTS UPWARDS OF AN INCH COULD LEAD TO
FLOODING. THE PERIOD OF DRY WEATHER THIS EVENING HELPS OFFSET A
WIDESPREAD THREAT OF HIGH WATER IN THE WATCH AREA.
SIDED WITH WARMEST GUIDANCE TONIGHT.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
COLD FRONT WILL BE EAST OF OUR AREA SUNDAY NIGHT AS ANY QPF LEFT
OVER ASSOCIATED WITH BAROCLINIC ZONE WILL AFFECT NRN WV MTNS AND
WRN MD UNTIL MID EVENING. A BRIEF PERIOD OF CLEARING MON EVENING
BEFORE CLOUDS ASSOCIATED WITH THE SURGE OF COLD AIR AND LOWER MID
LVL HEIGHTS ARRIVE FROM THE WEST.
MID LVL TROUGH SWEEPS THROUGH MON NGT - TUE. THIS IS ACCOMPANIED
BY MUCH COLDER AIR AS H8 TEMPS PLUMMET BACK INTO THE NEGATIVE MID
TEENS BY 12Z TUES. SCATTERED SNOW SHOWERS AND LAKE EFFECT SNOW
SHOWERS ARE PREDICTED MON NGT INTO TUES EVENING. WIND TRAJECTORY
IS NOT FAVORABLE FOR SIGNIFICANT SNOW ACCUMULATIONS. OUTSIDE THE
SNOW BELT OF NWRN PA...LOOK FOR MINOR ACCUMS AT BEST GIVEN SHORT
DURATION AND LACK OF FAVORABLE SNOW DYNAMICS AS NEEDED UPPER LEVEL
TEMPERATURES ARE BELOW REGION OF UPWARD VERTICAL MOTION.
ANTICYCLONIC FLOW RAPIDLY ENSUES DURING THE PREDAWN HOURS WEDNESDAY.
THIS WILL SHUT OFF THE LAKE EFFECT MACHINE AS SCOUR OUT CLOUDS.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
FOCUSED EFFORTS ON NEAR AND SHORT TERM TODAY...LATEST NUMERICAL
MODELS REMAIN CONSISTENT WITH WEATHER PATTER OVER THE LONG RANGE.
BELOW NORMAL TEMPS ARE PROJECTED FOR MUCH OF THE EXTENDED.
PREVIOUS DISCUSSION FOLLOWS:
BLDG HIGH PRES SHOULD END ANY SNOW SHWRS TUE EVE...WITH DRY WEATHER
CONTG WED. A WK CLIPPER IS PROGGED FOR THU...THOUGH TIMING AND
STRENGTH DIFFERENCES IN THE MDLS PRECLUDE MORE THAN A SLGT CHC
MENTION FOR SNOW SHWRS ATTM. BLDG HIGH PRES IS EXPD AGAIN BY THE
END OF THE WK. OVERALL...TEMPS SHOULD AVG BLO SEASONAL LVLS THRU
THE PD.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
MEDIUM CONFIDENCE FORECAST.
VFR WEATHER WILL CONTINUE FOR MUCH OF THE NIGHT SAVE FOR FKL WHERE
THEY SHOULD STAY WITH IFR/MVFR AS REGION RESIDES IN WARM SECTOR.
VCSH WAS INCLUDED IN ALL TERMINALS AS SCATTERED SHOWERS CONTINUE
TO ADVECT IN FROM THE SE.
A BRIEF PERIOD OF GUSTY WINDS AND REDUCED VISIBILITY WILL OCCUR
BEFORE DAYBREAK RESULTING FROM A LINE OF SHOWERS ALONG THE
LEADING EDGE OF THE FRONT. FOR NOW...USED THE FOLLOWING
TIMING...8Z ZZV...9Z OHIO RIVER...11Z-12Z DUJ-LBE. COULD EASILY
SEE A SHORT DURATION OF IFR WITH THIS ACTIVITY...BUT TOO SMALL
TEMPORAL DURATION FOR INCLUSION AT THIS JUNCTURE. MVFR
RESTRICTIONS WILL CONTINUE FOR MUCH OF SUN MRNG BEFORE CIGS LIFT
TO VFR BY AFTN. WINDS WILL BE GUSTY THROUGH THE PERIOD WITH GUSTS
AROUND 25KTS THROUGH SUN AFTN AT MOST AIRPORTS.
AREAS WITH MOST UNCERTAINTY...
- FKL COULD LIFT TO MVFR FOR A FEW HOURS THIS EVENING
- VIS/CIGS LIKELY WILL BE LOWER THAN FORECAST FOR A SHORT PERIOD
WITH ONSET OF PCPN ASSOCIATED WITH COLD FRONT
- COULD SEE VFR DEVELOP FASTER THAN CURRENTLY FORECAST...ESPECIALLY
ALONG AND S OF I-70
WINDS ARE STRONG /45-50KTS/ IN LOW LEVELS WITH LLWS A POTENTIAL
HAZARD ESPECIALLY AT VALLEY LOCATIONS.
.OUTLOOK.../00Z MONDAY THROUGH THURSDAY/...
CONTINUED IFR RESTRICTIONS WILL BE POSSIBLE MONDAY NIGHT THROUGH
TUESDAY NORTH OF INTERSTATE 80 DUE TO LAKE EFFECT SNOW SHOWERS.
OTHERWISE...NO OTHER WIDESPREAD WEATHER RELATED AVIATION HAZARDS
EXISTS.
&&
.HYDROLOGY...
A FLOOD WARNING IS IN EFFECT FOR WILLS CREEK AT CAMBRIDGE
AFFECTING GUERNSEY COUNTY AND THE MUSKINGUM RIVER AT COSHOCTON
AFFECTING COSHOCTON COUNTY. RAINFALL AMOUNTS OF 1.00 TO NEARLY
3.00 INCHES OF RAINFALL ARE EXPECTED OVER THE TUSCARAWAS RIVER AND
MUSKINGUM RIVER BASINS.
SHARP RISES ARE EXPECTED ON RIVERS AND STREAMS ACROSS EASTERN OHIO.
THESE RISES WILL BE SUFFICIENT FOR THE MUSKINGUM RIVER AT COSHOCTON
TO RISE ABOVE FLOOD STAGE SUNDAY AFTERNOON. WILLS CREEK WILL RISE
ABOVE FLOOD STAGE SUNDAY EVENING. MINOR FLOODING IS EXPECTED AT BOTH
LOCATIONS.
A FLOOD ADVISORY IS IN EFFECT FOR THE OHIO RIVER AT THE POINT IN
PITTSBURGH. THE OHIO RIVER IS EXPECTED TO RISE ABOVE 18.0 FEET AND
BEGIN TO FLOOD THE MONONGAHELA RIVER PARKING WHARF SUNDAY AFTERNOON.
THE OHIO RIVER THE CREST IS EXPECTED MONDAY AFTERNOON AT 21.8 FEET.
THIS WILL COMPLETELY FLOOD THE MONONGAHELA PARKING WHARF. AT THIS
TIME FLOOD WATERS ARE NOT EXPECTED TO AFFECT THE 10TH STREET
BYPASS. STRONG RISES ON THE OHIO RIVER ARE FORECAST SUNDAY WITH
CONTINUED ELEVATED LEVELS THROUGH TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR OHZ039>041-048-057.
PA...FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR PAZ007>009-013.
WV...NONE.
&&
$$
SYNOPSIS...98
NEAR TERM...98
SHORT TERM...98
LONG TERM...98/07
AVIATION...98
AREA FORECAST DISCUSSION
NWS DULUTH MN
904 PM CST SAT DEC 21 2013
.UPDATE...
ISSUED AT 904 PM CST SAT DEC 21 2013
LIGHT SNOW OR FLURRIES CONTINUED TO FALL OVER MUCH OF NORTHEAST
MINNESOTA THIS EVENING...WITH A STRONGER LAKE SNOW BAND NOW
EVIDENT JUST EAST OF THE TWIN PORTS MOVING WEST. WE DON`T PLAN ON
MAKING ANY CHANGES TO THE LAKE SNOW ADVISORY ALONG THE SOUTH SHORE
AT THIS TIME. CONSIDERABLE SHEAR EXISTS IN THE SURFACE TO 850MB
LAYER...WITH SURFACE/925MB WINDS NORTH TO NORTHEAST...AND THE
850MB FLOW EASTERLY. THIS IS NOT OUR TYPICAL SET UP FOR LES AND AT
THIS POINT...THE PLUMES ARE DOMINATED BY THE 850MB FLOW.
SIGNIFICANT SNOWFALL STILL LOOKS ON TRACK FOR THE SOUTH
SHORE...AND LATER SHIFTS MAY NEED TO UPGRADE PORTIONS OF THE
ADVISORY TO A WARNING.
WE ARE ALSO SEEING THE AFFECTS OF THE NORTHERN STREAM WAVE WITH THE
INVERTED TROUGH SHARPENING AND PRESSURE RISE MINIMUM OR SOME WEAK
FALLS OCCURRING ALONG THE INVERTED TROUGH. WEAK RETURNS ARE ALSO
EVIDENT ON AREA RADARS IN LINE WITH THE NAM. AS THIS LARGER SCALE
LIFT INCREASES OVERNIGHT...WE EXPECT LIGHT SNOW TO INCREASE IN
COVERAGE ACROSS THE REGION...AND FOR THE LAKE SNOW BANDS TO
INCREASE AS WELL. WE WILL CONTINUE TO MONITOR THE LATEST DATA AND
MAY HAVE TO CONSIDER AN ADVISORY FOR THE TWIN PORTS/COASTAL
LAKE/CARLTON COUNTY AREAS INTO AT LEAST SUNDAY OR SUNDAY EVENING
AS WE WILL BE UNDER THE INVERTED TROUGH AND THE EASTERLY 850MB
FLOW. SNOWFALL AMOUNTS SO FAR HAVE BEEN LIGHT...WITH
LUTSEN/SILVER BAY REPORTING AN INCH AS OF LATE AFTERNOON...AND
DULUTH ONLY A TENTH OR TWO AS OF MID EVENING.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 330 PM CST SAT DEC 21 2013
AT 330 PM...IT WAS FAIRLY QUIET ACROSS THE NORTHLAND. THERE
CONTINUED TO BE FLURRIES AND ISOLATED SNOW SHOWERS FOR MOST AREAS.
THE EXCEPTION WAS ALONG THE NORTH SHORE OF LAKE SUPERIOR...WHERE
AN INCH OF SNOW FELL THIS AFTERNOON IN COASTAL LAKE AND COOK
COUNTIES. TEMPERATURES RANGED FROM THE SINGLE DIGITS AT
INTERNATIONAL FALLS TO THE 20S IN NORTHWESTERN WISCONSIN.
THE HIGH RESOLUTION MODEL DATA INDICATES THAT THERE WILL BE
PERIODS OF LAKE EFFECT SNOW CONTINUING ACROSS WESTERN LAKE
SUPERIOR TONIGHT. THE HRRR AND WRF INDICATE A CONVERGENT BAND OF
SNOW ACROSS THE WESTERN PORTION OF THE LAKE...WITH SEVERAL WAVES
IN THE LINE. THIS WILL RESULT IN LOCAL SWIRLS AND CONSIDERABLE
VARIABILITY TO THE LAKE EFFECT OVERNIGHT. STRONG NORTHEAST WINDS
AT ROCK OF AGES CONTINUED ON ONE SIDE OF THIS BAND...WITH GUSTY
SOUTHERLY WINDS AT DEVILS ISLAND ON THE OTHER SIDE.
WINDS WILL OVERWHELMINGLY BECOME NORTHEAST TO NORTH OVERNIGHT AND
ON SUNDAY...WHILE THE OTHER SYSTEM MOVES IN FROM THE WEST. THE
RESULT WILL BE A PHASING OF THE MOISTURE ACROSS THE WESTERN GREAT
LAKES. OVERALL LOOKING FOR AN INCH OR TWO FOR MUCH OF THE AREA
TONIGHT...AND ANOTHER INCH OR TWO ON SUNDAY.
THE EXCEPTION WILL BE ACROSS THE SOUTH SHORE OF LAKE SUPERIOR. WE
COULD HAVE HANDLED THIS EVENT IN A COUPLE WAYS REGARDING HEADLINES
BUT AFTER EXTENSIVE DISCUSSION...WE DECIDED TO ISSUE A LAKE EFFECT
SNOW ADVISORY FOR THE PERIOD TONIGHT THROUGH MONDAY...RATHER THAN
HAVING A LARGE LAKE EFFECT SNOW WARNING OUT FOR 5 PERIODS...WITH
GENERALLY ADVISORY TYPE SNOW FOR MOST OF THE PERIODS. THINK THERE
IS A FAIR CHANCE WE MAY NEED TO UPGRADE TO A WARNING FOR MONDAY.
BUT FOR TONIGHT AND SUNDAY...WE ARE LOOKING AT TRANSITIONAL LAKE
EFFECT SNOWFALL BANDS...SWIRLS AND CONVERGENCE BANDS...AND THE
RESULT SHOULD BE WIDESPREAD ADVISORY TYPE SNOW.
WE ALSO COULD HAVE ISSUED THE ADVISORY FOR TONIGHT THROUGH SUNDAY
NIGHT...AND MAINTAINED THE WATCH FOR MONDAY...BUT FOR SIMPLICITY
SAKE...DECIDED TO HOLD OFF ON THAT FOR NOW. THE MAIN FOCUS FOR A
POTENTIAL WARNING ON MONDAY WOULD BE THE GOGEBIC RANGE. WE DO
AGREE THAT ADDED UP OVER 4-5 PERIODS...THE AMOUNTS COULD BE
IMPRESSIVE...SOME ON THE ORDER OF A FOOT OR MORE IN THE GOGEBIC
RANGE.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 PM CST SAT DEC 21 2013
FIRST CONCERN IN EXTENDED IS ON LONG DURATION LAKE EFFECT SNOW THAT
WILL PERSIST THROUGH MONDAY EVENING. THE 12Z RUNS OF THE
GFS/ECM/NAM ARE IN AGREEMENT THAT THE H85-H50 TROUGH AXIS PASSES
OVER WRN LAKE SUPERIOR DURING THE DAY MONDAY...BRINGING A STRONG
PUSH OF CAA WITH H85 TEMPS FALLING INTO THE NEGATIVE 20S AND
BOUNDARY LAYER WINDS BACKING OUT OF THE NORTH THEN NORTHWEST.
ALTHOUGH CONDITIONS REMAIN FAVORABLE FOR A FEW INCHES OF LIGHT SNOW
ALONG THE SOUTH SHORE OF LAKE SUPERIOR SUN NIGHT...LAPSE
RATES/INVERSION HTS SIGNIFICANTLY INCREASE MONDAY DUE TO THE ARRIVAL
OF THE COLD AIR. HAVE INCREASED QPF/SN AMOUNTS MONDAY TO ACCOUNT
FOR THE HIGHER INSTABILITY.
FOCUS TURNS TO ELONGATED VORT MAX THAT DROPS OUT OF CANADA AND
ACROSS THE NRN PLAINS TUESDAY/WEDNESDAY. LATEST ECM/GFS BOTH
SUGGEST THE DIGGING WAVE...WITH SFC REFLECTION COLD FRONT...SWEEPS
ACROSS THE NORTHLAND DURING THE CHRISTMAS HOLIDAY. CURRENT TIMING
WOULD FAVOR A FEW INCHES OF SNOW OVER MUCH OF THE REGION TUESDAY
NIGHT. HOWEVER...IF TIMING SLOWS...ITS POSSIBLE THE COLD FRONT/LIGHT
SNOW HOLD OFF UNTIL CHRISTMAS DAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 548 PM CST SAT DEC 21 2013
MVFR CEILINGS COVERED MOST OF THE NORTHLAND THIS EVENING...AND
THAT WILL CONTINUE THROUGH THE PERIOD. LIGHT SNOW OR FLURRIES WERE
FALLING OUT OF THESE CEILINGS IN SPOTS...WITH LIGHT TO AT TIMES
MODERATE SNOW OCCURRING AROUND LAKE SUPERIOR...MAINLY ALONG THE
NORTH SHORE INTO THE TWIN PORTS TO NORTHERN BAYFIELD COUNTY. A
NORTHERN STREAM SHORTWAVE WILL PHASE WITH THE SOUTHERN STREAM SYSTEM
SUNDAY AND CAUSE AN INVERTED TROUGH TO FORM OVER THE REGION. THIS
WILL CAUSE ADDITIONAL SNOW TO DEVELOP ACROSS MUCH OF THE REGION
LATER TONIGHT INTO SUNDAY WITH ADDITIONAL ACCUMULATION. IFR VSBYS
WILL OCCUR AT TIMES IN THE SNOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 8 13 -8 1 / 80 90 70 20
INL -9 2 -20 -5 / 40 50 20 10
BRD 4 11 -13 -2 / 70 90 50 10
HYR 11 21 1 6 / 60 90 80 70
ASX 11 21 9 9 / 70 90 90 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...LAKE EFFECT SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST
MONDAY FOR WIZ001>004.
LS...SMALL CRAFT ADVISORY UNTIL 4 AM CST MONDAY FOR LSZ121-140>148.
&&
$$
UPDATE...MELDE
SHORT TERM...DAP
LONG TERM...GRANING
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS DULUTH MN
548 PM CST SAT DEC 21 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 330 PM CST SAT DEC 21 2013
AT 330 PM...IT WAS FAIRLY QUIET ACROSS THE NORTHLAND. THERE
CONTINUED TO BE FLURRIES AND ISOLATED SNOW SHOWERS FOR MOST AREAS.
THE EXCEPTION WAS ALONG THE NORTH SHORE OF LAKE SUPERIOR...WHERE
AN INCH OF SNOW FELL THIS AFTERNOON IN COASTAL LAKE AND COOK
COUNTIES. TEMPERATURES RANGED FROM THE SINGLE DIGITS AT
INTERNATIONAL FALLS TO THE 20S IN NORTHWESTERN WISCONSIN.
THE HIGH RESOLUTION MODEL DATA INDICATES THAT THERE WILL BE
PERIODS OF LAKE EFFECT SNOW CONTINUING ACROSS WESTERN LAKE
SUPERIOR TONIGHT. THE HRRR AND WRF INDICATE A CONVERGENT BAND OF
SNOW ACROSS THE WESTERN PORTION OF THE LAKE...WITH SEVERAL WAVES
IN THE LINE. THIS WILL RESULT IN LOCAL SWIRLS AND CONSIDERABLE
VARIABILITY TO THE LAKE EFFECT OVERNIGHT. STRONG NORTHEAST WINDS
AT ROCK OF AGES CONTINUED ON ONE SIDE OF THIS BAND...WITH GUSTY
SOUTHERLY WINDS AT DEVILS ISLAND ON THE OTHER SIDE.
WINDS WILL OVERWHELMINGLY BECOME NORTHEAST TO NORTH OVERNIGHT AND
ON SUNDAY...WHILE THE OTHER SYSTEM MOVES IN FROM THE WEST. THE
RESULT WILL BE A PHASING OF THE MOISTURE ACROSS THE WESTERN GREAT
LAKES. OVERALL LOOKING FOR AN INCH OR TWO FOR MUCH OF THE AREA
TONIGHT...AND ANOTHER INCH OR TWO ON SUNDAY.
THE EXCEPTION WILL BE ACROSS THE SOUTH SHORE OF LAKE SUPERIOR. WE
COULD HAVE HANDLED THIS EVENT IN A COUPLE WAYS REGARDING HEADLINES
BUT AFTER EXTENSIVE DISCUSSION...WE DECIDED TO ISSUE A LAKE EFFECT
SNOW ADVISORY FOR THE PERIOD TONIGHT THROUGH MONDAY...RATHER THAN
HAVING A LARGE LAKE EFFECT SNOW WARNING OUT FOR 5 PERIODS...WITH
GENERALLY ADVISORY TYPE SNOW FOR MOST OF THE PERIODS. THINK THERE
IS A FAIR CHANCE WE MAY NEED TO UPGRADE TO A WARNING FOR MONDAY.
BUT FOR TONIGHT AND SUNDAY...WE ARE LOOKING AT TRANSITIONAL LAKE
EFFECT SNOWFALL BANDS...SWIRLS AND CONVERGENCE BANDS...AND THE
RESULT SHOULD BE WIDESPREAD ADVISORY TYPE SNOW.
WE ALSO COULD HAVE ISSUED THE ADVISORY FOR TONIGHT THROUGH SUNDAY
NIGHT...AND MAINTAINED THE WATCH FOR MONDAY...BUT FOR SIMPLICITY
SAKE...DECIDED TO HOLD OFF ON THAT FOR NOW. THE MAIN FOCUS FOR A
POTENTIAL WARNING ON MONDAY WOULD BE THE GOGEBIC RANGE. WE DO
AGREE THAT ADDED UP OVER 4-5 PERIODS...THE AMOUNTS COULD BE
IMPRESSIVE...SOME ON THE ORDER OF A FOOT OR MORE IN THE GOGEBIC
RANGE.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 PM CST SAT DEC 21 2013
FIRST CONCERN IN EXTENDED IS ON LONG DURATION LAKE EFFECT SNOW THAT
WILL PERSIST THROUGH MONDAY EVENING. THE 12Z RUNS OF THE
GFS/ECM/NAM ARE IN AGREEMENT THAT THE H85-H50 TROUGH AXIS PASSES
OVER WRN LAKE SUPERIOR DURING THE DAY MONDAY...BRINGING A STRONG
PUSH OF CAA WITH H85 TEMPS FALLING INTO THE NEGATIVE 20S AND
BOUNDARY LAYER WINDS BACKING OUT OF THE NORTH THEN NORTHWEST.
ALTHOUGH CONDITIONS REMAIN FAVORABLE FOR A FEW INCHES OF LIGHT SNOW
ALONG THE SOUTH SHORE OF LAKE SUPERIOR SUN NIGHT...LAPSE
RATES/INVERSION HTS SIGNIFICANTLY INCREASE MONDAY DUE TO THE ARRIVAL
OF THE COLD AIR. HAVE INCREASED QPF/SN AMOUNTS MONDAY TO ACCOUNT
FOR THE HIGHER INSTABILITY.
FOCUS TURNS TO ELONGATED VORT MAX THAT DROPS OUT OF CANADA AND
ACROSS THE NRN PLAINS TUESDAY/WEDNESDAY. LATEST ECM/GFS BOTH
SUGGEST THE DIGGING WAVE...WITH SFC REFLECTION COLD FRONT...SWEEPS
ACROSS THE NORTHLAND DURING THE CHRISTMAS HOLIDAY. CURRENT TIMING
WOULD FAVOR A FEW INCHES OF SNOW OVER MUCH OF THE REGION TUESDAY
NIGHT. HOWEVER...IF TIMING SLOWS...ITS POSSIBLE THE COLD FRONT/LIGHT
SNOW HOLD OFF UNTIL CHRISTMAS DAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 548 PM CST SAT DEC 21 2013
MVFR CEILINGS COVERED MOST OF THE NORTHLAND THIS EVENING...AND
THAT WILL CONTINUE THROUGH THE PERIOD. LIGHT SNOW OR FLURRIES WERE
FALLING OUT OF THESE CEILINGS IN SPOTS...WITH LIGHT TO AT TIMES
MODERATE SNOW OCCURRING AROUND LAKE SUPERIOR...MAINLY ALONG THE
NORTH SHORE INTO THE TWIN PORTS TO NORTHERN BAYFIELD COUNTY. A
NORTHERN STREAM SHORTWAVE WILL PHASE WITH THE SOUTHERN STREAM SYSTEM
SUNDAY AND CAUSE AN INVERTED TROUGH TO FORM OVER THE REGION. THIS
WILL CAUSE ADDITIONAL SNOW TO DEVELOP ACROSS MUCH OF THE REGION
LATER TONIGHT INTO SUNDAY WITH ADDITIONAL ACCUMULATION. IFR VSBYS
WILL OCCUR AT TIMES IN THE SNOW.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 8 13 -8 1 / 70 90 70 20
INL -9 2 -20 -5 / 40 50 20 10
BRD 4 11 -13 -2 / 70 90 50 10
HYR 11 21 1 6 / 60 90 80 70
ASX 15 21 9 9 / 70 90 90 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...LAKE EFFECT SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST
MONDAY FOR WIZ001>004.
LS...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 AM CST MONDAY
FOR LSZ121-140>148.
&&
$$
SHORT TERM...DAP
LONG TERM...GRANING
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1218 PM CST FRI DEC 20 2013
.UPDATED FOR 18Z AVIATION DISCUSSION...
ISSUED AT 1209 PM CST FRI DEC 20 2013
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CST FRI DEC 20 2013
SNOW BEGINNING TO TAPER OFF ACROSS THE AREA THIS MORNING AS WEAK
ISENTROPIC UPGLIDE WE HAD IS SLOWLY FADING AWAY. BEST EVIDENCE OF
THE LOSS OF LIFT WAS THE CONSIDERABLE AMOUNT OF WARMING WE SAW WITH
CLOUD TOP TEMPS BETWEEN 5Z AND 7Z...IR WARMING THESE TWO HOURS
MATCHED UP WELL WITH THE LOSS OF SNOW OBSERVATIONS. THERE WILL BE
ONE MORE POTENTIAL SNOW BAND TO WATCH OUT FOR THIS MORNING FROM
SOUTH CENTRAL MN TOWARD THE EAU CLAIRE AREA. LOOKING BACK OVER THE
ERN NEB/SODAK BORDER...THERE HAS BEEN A BAND OF COOLING CLOUD TOPS
THE LAST COUPLE OF HOURS...WHICH IS ASSOCIATED A SECTION OF THE
H7-H6 FGEN THAT THE RAP SHOWS BECOMING ACTIVE ONCE AGAIN. THIS IS
BEING AIDED BY A SLIGHT LOWERING OF THE TROPOPAUSE LEVEL THAT
EMANATED FROM THE PRIMARY UPPER TROUGH OVER THE ROCKIES LAST NIGHT.
THIS BAND OF FGEN WILL SLIDE EAST THROUGH THE MORNING AND MOST
HI-RES MODELS...ALONG WITH THE 20.00/20.06 NAM12 SHOW ONE LAST BAND
OF SNOW CUTTING ACROSS OR NEAR THE SE CORNER OF THE MPX CWA BETWEEN
ABOUT 14Z AND 18Z.
THE BIGGER QUESTION FOR TODAY THOUGH IS WHAT WILL HAPPEN WITH THE
CLOUD COVER. SEEING SOME CONFLICTING TRENDS WITH THE CLOUD COVER
EARLY THIS MORNING...WHICH IS HELPING MAKE THE CLOUD FORECAST RATHER
DIFFICULT. A VERY DRY HIGH PRESSURE OF CONTINENTAL POLAR ORIGIN IS
CURRENTLY CENTERED FROM CENTRAL SODAK INTO NORTH CENTRAL MN. WITHIN
THIS HIGH WE ARE SEEING CLOUD HEIGHTS INCREASE OR EVEN CLEAR OUT
ACROSS CENTRAL MN...BUT BENEATH THE RIDGE OVER SODAK...THEY HAVE
BEEN EXPANDING THE LAST FEW HOURS. OVER SRN MN...THE CLOUDS HAVE
FINALLY BEGUN TO LOWER AS SLIGHTLY MORE MOIST AIR HAS BEEN PUSHED
NORTH OF THE STALLED OUT BOUNDARY THAT SITS FROM NE OKLAHOMA INTO
SRN MICH. THE MODELS SHOW PLENTY OF LOW LEVEL MOISTURE HANGING
AROUND THROUGH THE DAY...INDICATING A MOSTLY CLOUDY DAY IS IN
STORE...BUT SUSPECT THAT DRIER AIR OVER NRN MN WILL HELP KEEP THE
CLOUDS THINNER ACROSS NRN PORTIONS OF THE AREA. THE NAM/GFS SHOW
EVEN THE LOW LEVEL MOISTURE STARTING TO EVACUATE WRN MN
TONIGHT...WITH MOSTLY CLEAR SKIES WORKING INTO THE WEST LATE. IF
THIS HAPPENS...WE WILL PROBABLY HAVE TO TREND LOWS TONIGHT IN THE
WEST CLOSER TO THE COOL END OF GUIDANCE...WHICH SHOWS LOWS DROPPING
BACK DOWN INTO THE TEENS BELOW ZERO IN THE WEST AS IS SEEN WITH
GEM/ECMWF/NAM.
AS FOR THE MOISTURE AHEAD OF THE BOUNDARY TO OUR SOUTHEAST...IT IS
QUITE IMPRESSIVE. LOW LEVEL AIR TRAJECTORIES SHOW THAT THE AIR IN
THE WARM SECTOR OF THE SYSTEM TO OUR SOUTH CAN BE TRACED BACK TO NOT
JUST THE GULF OF MEXICO...BUT CLEAR DOWN INTO THE NRN CARIBBEAN AND
BACK EAST ACROSS CUBA INTO THE TROPICAL WRN ATLANTIC...HENCE WHY
HISTORIC RAINFALLS ARE EXPECTED IN THE COMING DAYS ACROSS THE OHIO
VALLEY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 400 AM CST FRI DEC 20 2013
THE ARCTIC FRONT WILL OSCILLATE BACK AND FORTH ACROSS THE FORECAST
AREA DURING THE LONGER TERM. THIS WILL OFFER AT LEAST TWO SNOW
EVENTS AS WAVES OF LOW PRESSURE MOVE THROUGH FROM SUNDAY INTO
MONDAY AND THEN FROM TUESDAY INTO WEDNESDAY. SNOW ACCUMULATIONS OF AN
INCH OR TWO ARE POSSIBLE WITH EACH EVENT. FAIRLY STRONG HIGH
PRESSURE WILL FOLLOW EACH OF THESE WAVES. MONDAY MORNING STILL
LOOKS THE COLDEST WITH LOWS FROM NEAR 20 BELOW IN WEST CENTRAL MN
TO AROUND ZERO AT KEAU. COUPLE THIS WITH NORTHWEST WINDS NEAR 10
MPH AND WIND CHILL READINGS COME OUT TO AROUND 35 BELOW ZERO
ACROSS THE WESTERN CWA. HIGHS ON MONDAY WILL LIKELY STAY BELOW
ZERO ACROSS THE WEST WITH SINGLE DIGITS ABOVE ZERO FOR THE TWIN
CITIES AND WEST CENTRAL WI. A NON-DIURNAL TEMPERATURE TREND WAS
THEN INSERTED FOR MONDAY NIGHT ACROSS WEST CENTRAL AND SOUTHWEST
MN AS SOUTHERLY FLOW INCREASES ON THE BACK SIDE OF THE HIGH AS THE
NEXT WAVE OF LOW PRESSURE MOVES INTO THE DAKOTAS. CENTRAL AREAS OF
MN AND WEST CENTRAL WI WILL STILL HAVE A VERY COLD NIGHT WITH LOWS
MONDAY NIGHT FROM 10 BELOW TO 15 BELOW ZERO. THE WAVE OF LOW
PRESSURE ARRIVING ON TUESDAY POSES SOME PRECIP TYPE PROBLEMS FOR
SOUTHWEST MN WITH THE GFS INDICATING SOME POTENTIAL FOR FREEZING
DRIZZLE/FREEZING RAIN. THE ECMWF IS NOT AS AGGRESSIVE WITH THE LOW
LEVEL WARMING...PARTLY BECAUSE THE WHOLE UPPER WAVE IS FARTHER
SOUTH COMPARED TO THE GFS. THE ECMWF HAS DEEPER SATURATION AS
WELL. POPS FOR THE TUESDAY AND WEDNESDAY PERIOD WILL LIKELY NEED
TO BE ADJUSTED UPWARD IF THE POSITION OF THE GFS GETS CLOSER TO
THE ECMWF. POPS WERE EXPANDED AND ADJUSTED UPWARD FOR THE WAVE
FROM SUNDAY INTO MONDAY AS THE NORTHERN STREAM HAS BECOME
STRONGER. THE OTHER PROBLEM ON SUNDAY TO KEEP AN EYE ON IS THE
BLOWING SNOW FROM WEST CENTRAL INTO SOUTH CENTRAL MN. WITH MORE
WIDESPREAD SNOW FORECAST ALONG WITH INCREASING NORTHWEST WINDS AS
THE NEXT SURGE OF ARCTIC PUSHES IN...SOME PRETTY POOR VISIBILITIES
MAY RESULT ACROSS THE MN RIVER VALLEY DURING THE AFTERNOON AND NIGHT.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1209 PM CST FRI DEC 20 2013
THE POTENTIAL FOR MVFR/IFR CLOUDS IS MAKING FOR A TROUBLING
FORECAST THIS AFTERNOON. THE FORECAST MODELS ARE HAVING TROUBLE
WITH THE STAGNANT AIRMASS IN PLACE. BASED ON THE CURRENT
CONDITIONS...AND THE SPORADIC MVFR CIGS ACROSS THE REGION HAVE
TRENDED FOR A MORE PESSIMISTIC FORECAST.
KMSP...
PESKY FLURRIES WILL LINGER FOR A COUPLE OF MORE HOURS...BUT SHOULD
NOT SEE ANY ACCUMULATIONS. AS MENTIONED ABOVE...THE MAIN CONCERN
IS CLOUDS OVERNIGHT...BUT FOR NOW DID NOT HAVE THE CONFIDENCE TO
DROP MSP BELOW 1700FT.
/OUTLOOK FOR KMSP/
SUN...MVFR AND -SN WITH IFR POSSIBLE. WINDS NW AT 15G20KTS.
MON...VFR. WINDS NW AT 5-10KTS.
TUE...VFR WITH MVFR AND -SN POSSIBLE. WIND S AT 15G25KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MPG
LONG TERM...RAH
AVIATION...JRB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
608 AM CST FRI DEC 20 2013
.UPDATE...
12Z AVIATION DISCUSSION ADDED BELOW.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CST FRI DEC 20 2013
SNOW BEGINNING TO TAPER OFF ACROSS THE AREA THIS MORNING AS WEAK
ISENTROPIC UPGLIDE WE HAD IS SLOWLY FADING AWAY. BEST EVIDENCE OF
THE LOSS OF LIFT WAS THE CONSIDERABLE AMOUNT OF WARMING WE SAW WITH
CLOUD TOP TEMPS BETWEEN 5Z AND 7Z...IR WARMING THESE TWO HOURS
MATCHED UP WELL WITH THE LOSS OF SNOW OBSERVATIONS. THERE WILL BE
ONE MORE POTENTIAL SNOW BAND TO WATCH OUT FOR THIS MORNING FROM
SOUTH CENTRAL MN TOWARD THE EAU CLAIRE AREA. LOOKING BACK OVER THE
ERN NEB/SODAK BORDER...THERE HAS BEEN A BAND OF COOLING CLOUD TOPS
THE LAST COUPLE OF HOURS...WHICH IS ASSOCIATED A SECTION OF THE
H7-H6 FGEN THAT THE RAP SHOWS BECOMING ACTIVE ONCE AGAIN. THIS IS
BEING AIDED BY A SLIGHT LOWERING OF THE TROPOPAUSE LEVEL THAT
EMANATED FROM THE PRIMARY UPPER TROUGH OVER THE ROCKIES LAST NIGHT.
THIS BAND OF FGEN WILL SLIDE EAST THROUGH THE MORNING AND MOST
HI-RES MODELS...ALONG WITH THE 20.00/20.06 NAM12 SHOW ONE LAST BAND
OF SNOW CUTTING ACROSS OR NEAR THE SE CORNER OF THE MPX CWA BETWEEN
ABOUT 14Z AND 18Z.
THE BIGGER QUESTION FOR TODAY THOUGH IS WHAT WILL HAPPEN WITH THE
CLOUD COVER. SEEING SOME CONFLICTING TRENDS WITH THE CLOUD COVER
EARLY THIS MORNING...WHICH IS HELPING MAKE THE CLOUD FORECAST RATHER
DIFFICULT. A VERY DRY HIGH PRESSURE OF CONTINENTAL POLAR ORIGIN IS
CURRENTLY CENTERED FROM CENTRAL SODAK INTO NORTH CENTRAL MN. WITHIN
THIS HIGH WE ARE SEEING CLOUD HEIGHTS INCREASE OR EVEN CLEAR OUT
ACROSS CENTRAL MN...BUT BENEATH THE RIDGE OVER SODAK...THEY HAVE
BEEN EXPANDING THE LAST FEW HOURS. OVER SRN MN...THE CLOUDS HAVE
FINALLY BEGUN TO LOWER AS SLIGHTLY MORE MOIST AIR HAS BEEN PUSHED
NORTH OF THE STALLED OUT BOUNDARY THAT SITS FROM NE OKLAHOMA INTO
SRN MICH. THE MODELS SHOW PLENTY OF LOW LEVEL MOISTURE HANGING
AROUND THROUGH THE DAY...INDICATING A MOSTLY CLOUDY DAY IS IN
STORE...BUT SUSPECT THAT DRIER AIR OVER NRN MN WILL HELP KEEP THE
CLOUDS THINNER ACROSS NRN PORTIONS OF THE AREA. THE NAM/GFS SHOW
EVEN THE LOW LEVEL MOISTURE STARTING TO EVACUATE WRN MN
TONIGHT...WITH MOSTLY CLEAR SKIES WORKING INTO THE WEST LATE. IF
THIS HAPPENS...WE WILL PROBABLY HAVE TO TREND LOWS TONIGHT IN THE
WEST CLOSER TO THE COOL END OF GUIDANCE...WHICH SHOWS LOWS DROPPING
BACK DOWN INTO THE TEENS BELOW ZERO IN THE WEST AS IS SEEN WITH
GEM/ECMWF/NAM.
AS FOR THE MOISTURE AHEAD OF THE BOUNDARY TO OUR SOUTHEAST...IT IS
QUITE IMPRESSIVE. LOW LEVEL AIR TRAJECTORIES SHOW THAT THE AIR IN
THE WARM SECTOR OF THE SYSTEM TO OUR SOUTH CAN BE TRACED BACK TO NOT
JUST THE GULF OF MEXICO...BUT CLEAR DOWN INTO THE NRN CARIBBEAN AND
BACK EAST ACROSS CUBA INTO THE TROPICAL WRN ATLANTIC...HENCE WHY
HISTORIC RAINFALLS ARE EXPECTED IN THE COMING DAYS ACROSS THE OHIO
VALLEY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 400 AM CST FRI DEC 20 2013
THE ARCTIC FRONT WILL OSCILLATE BACK AND FORTH ACROSS THE FORECAST
AREA DURING THE LONGER TERM. THIS WILL OFFER AT LEAST TWO SNOW
EVENTS AS WAVES OF LOW PRESSURE MOVE THROUGH FROM SUNDAY INTO
MONDAY AND THEN FROM TUESDAY INTO WEDNESDAY. SNOW ACCUMULATIONS OF AN
INCH OR TWO ARE POSSIBLE WITH EACH EVENT. FAIRLY STRONG HIGH
PRESSURE WILL FOLLOW EACH OF THESE WAVES. MONDAY MORNING STILL
LOOKS THE COLDEST WITH LOWS FROM NEAR 20 BELOW IN WEST CENTRAL MN
TO AROUND ZERO AT KEAU. COUPLE THIS WITH NORTHWEST WINDS NEAR 10
MPH AND WIND CHILL READINGS COME OUT TO AROUND 35 BELOW ZERO
ACROSS THE WESTERN CWA. HIGHS ON MONDAY WILL LIKELY STAY BELOW
ZERO ACROSS THE WEST WITH SINGLE DIGITS ABOVE ZERO FOR THE TWIN
CITIES AND WEST CENTRAL WI. A NON-DIURNAL TEMPERATURE TREND WAS
THEN INSERTED FOR MONDAY NIGHT ACROSS WEST CENTRAL AND SOUTHWEST
MN AS SOUTHERLY FLOW INCREASES ON THE BACK SIDE OF THE HIGH AS THE
NEXT WAVE OF LOW PRESSURE MOVES INTO THE DAKOTAS. CENTRAL AREAS OF
MN AND WEST CENTRAL WI WILL STILL HAVE A VERY COLD NIGHT WITH LOWS
MONDAY NIGHT FROM 10 BELOW TO 15 BELOW ZERO. THE WAVE OF LOW
PRESSURE ARRIVING ON TUESDAY POSES SOME PRECIP TYPE PROBLEMS FOR
SOUTHWEST MN WITH THE GFS INDICATING SOME POTENTIAL FOR FREEZING
DRIZZLE/FREEZING RAIN. THE ECMWF IS NOT AS AGGRESSIVE WITH THE LOW
LEVEL WARMING...PARTLY BECAUSE THE WHOLE UPPER WAVE IS FARTHER
SOUTH COMPARED TO THE GFS. THE ECMWF HAS DEEPER SATURATION AS
WELL. POPS FOR THE TUESDAY AND WEDNESDAY PERIOD WILL LIKELY NEED
TO BE ADJUSTED UPWARD IF THE POSITION OF THE GFS GETS CLOSER TO
THE ECMWF. POPS WERE EXPANDED AND ADJUSTED UPWARD FOR THE WAVE
FROM SUNDAY INTO MONDAY AS THE NORTHERN STREAM HAS BECOME
STRONGER. THE OTHER PROBLEM ON SUNDAY TO KEEP AN EYE ON IS THE
BLOWING SNOW FROM WEST CENTRAL INTO SOUTH CENTRAL MN. WITH MORE
WIDESPREAD SNOW FORECAST ALONG WITH INCREASING NORTHWEST WINDS AS
THE NEXT SURGE OF ARCTIC PUSHES IN...SOME PRETTY POOR VISIBILITIES
MAY RESULT ACROSS THE MN RIVER VALLEY DURING THE AFTERNOON AND NIGHT.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 539 AM CST FRI DEC 20 2013
LOW CONFIDENCE CIG FORECAST THIS PERIOD. MODEL FOLLOWED CLOSEST
FOR THIS PACKAGE WAS THE TREND FROM THE SREF FOR CIGS LESS THAN 3K
FEET...WHICH HAS A GOOD HANDEL OUT THE GATE ANYWAYS OF THE
CONFIGURATION OF MVFR CIGS ACROSS SRN MN...THEN UP THE MN/SD
BORDER. THOUGH WE HAVE SEEN CLEARING ACROSS CENTRAL MN...CLOUDS
HAVE BEEN FILLING BACK IN FOR THE LAST HOUR AND CURRENT TRENDS
WOULD INDICATE AXN WILL CLOUD BACK IN SHORTLY THIS MORNING. AFTER
THAT...NOT REALLY SEEING A STRONG SIGNAL FOR CLOUDS TO START
CLEARING OUT UNTIL AFTER 6Z ACROSS WRN MN. EXPECT CIGS TO BE MVFR
AT WORST...THOUGH IFR CIGS CAN NOT BE RULED OUT THIS EVENING AT
EAU AS THIS IS WHERE MODELS PEG DEWPOINTS TO INCREASE TO NEAR 20
DEGS THIS AFTERNOON. THAT EXTRA LOW LEVEL MOISTURE TONIGHT MAY
ALLOW FOR CIGS TO DROP TO IFR LEVELS. AS FOR SNOW...CONFIDENCE IS
HIGH THAT IT IS FINISHED FOR ALL TERMINALS.
KMSP...EXPECT CLOUDY CONDITIONS TO PREVAIL TODAY WITH THE MAIN
QUESTION BEING WHEN/IF THOSE CIGS COME BACK TO MVFR LEVELS. MAY
COME EARLIER THAN CURRENTLY INDICATED...BUT HAVE 00Z BASED ON WHEN
SREF PROBS FOR CIGS LESS THAN 3K FT INCREASE...WHICH IS COINCIDENT
WITH MEAN 925-850MB WIND SWITCHING OVER THE SW...HELPING BRING THE
LOWER CIGS THAT WILL BE DOWN TOWARD IA BACK TOWARD MSP. FOR NOW
HAVE CIGS REMAINING ABOVE 017...BUT COULD CERTAINLY SEE THEM DIP
BELOW THAT LEVEL TONIGHT.
/OUTLOOK FOR KMSP/
SAT...BECOMING VFR. WNDS LGT AND VRB.
SUN...MVFR CIGS/VSBYS POSSIBLE WITH -SN. WNDS WNW 15-20G25-30KT.
MON...VFR. WINDS NW 5-10 KTS.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MPG
LONG TERM...RAH
AVIATION...MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
400 AM CST FRI DEC 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 400 AM CST FRI DEC 20 2013
SNOW BEGINNING TO TAPER OFF ACROSS THE AREA THIS MORNING AS WEAK
ISENTROPIC UPGLIDE WE HAD IS SLOWLY FADING AWAY. BEST EVIDENCE OF
THE LOSS OF LIFT WAS THE CONSIDERABLE AMOUNT OF WARMING WE SAW WITH
CLOUD TOP TEMPS BETWEEN 5Z AND 7Z...IR WARMING THESE TWO HOURS
MATCHED UP WELL WITH THE LOSS OF SNOW OBSERVATIONS. THERE WILL BE
ONE MORE POTENTIAL SNOW BAND TO WATCH OUT FOR THIS MORNING FROM
SOUTH CENTRAL MN TOWARD THE EAU CLAIRE AREA. LOOKING BACK OVER THE
ERN NEB/SODAK BORDER...THERE HAS BEEN A BAND OF COOLING CLOUD TOPS
THE LAST COUPLE OF HOURS...WHICH IS ASSOCIATED A SECTION OF THE
H7-H6 FGEN THAT THE RAP SHOWS BECOMING ACTIVE ONCE AGAIN. THIS IS
BEING AIDED BY A SLIGHT LOWERING OF THE TROPOPAUSE LEVEL THAT
EMANATED FROM THE PRIMARY UPPER TROUGH OVER THE ROCKIES LAST NIGHT.
THIS BAND OF FGEN WILL SLIDE EAST THROUGH THE MORNING AND MOST
HI-RES MODELS...ALONG WITH THE 20.00/20.06 NAM12 SHOW ONE LAST BAND
OF SNOW CUTTING ACROSS OR NEAR THE SE CORNER OF THE MPX CWA BETWEEN
ABOUT 14Z AND 18Z.
THE BIGGER QUESTION FOR TODAY THOUGH IS WHAT WILL HAPPEN WITH THE
CLOUD COVER. SEEING SOME CONFLICTING TRENDS WITH THE CLOUD COVER
EARLY THIS MORNING...WHICH IS HELPING MAKE THE CLOUD FORECAST RATHER
DIFFICULT. A VERY DRY HIGH PRESSURE OF CONTINENTAL POLAR ORIGIN IS
CURRENTLY CENTERED FROM CENTRAL SODAK INTO NORTH CENTRAL MN. WITHIN
THIS HIGH WE ARE SEEING CLOUD HEIGHTS INCREASE OR EVEN CLEAR OUT
ACROSS CENTRAL MN...BUT BENEATH THE RIDGE OVER SODAK...THEY HAVE
BEEN EXPANDING THE LAST FEW HOURS. OVER SRN MN...THE CLOUDS HAVE
FINALLY BEGUN TO LOWER AS SLIGHTLY MORE MOIST AIR HAS BEEN PUSHED
NORTH OF THE STALLED OUT BOUNDARY THAT SITS FROM NE OKLAHOMA INTO
SRN MICH. THE MODELS SHOW PLENTY OF LOW LEVEL MOISTURE HANGING
AROUND THROUGH THE DAY...INDICATING A MOSTLY CLOUDY DAY IS IN
STORE...BUT SUSPECT THAT DRIER AIR OVER NRN MN WILL HELP KEEP THE
CLOUDS THINNER ACROSS NRN PORTIONS OF THE AREA. THE NAM/GFS SHOW
EVEN THE LOW LEVEL MOISTURE STARTING TO EVACUATE WRN MN
TONIGHT...WITH MOSTLY CLEAR SKIES WORKING INTO THE WEST LATE. IF
THIS HAPPENS...WE WILL PROBABLY HAVE TO TREND LOWS TONIGHT IN THE
WEST CLOSER TO THE COOL END OF GUIDANCE...WHICH SHOWS LOWS DROPPING
BACK DOWN INTO THE TEENS BELOW ZERO IN THE WEST AS IS SEEN WITH
GEM/ECMWF/NAM.
AS FOR THE MOISTURE AHEAD OF THE BOUNDARY TO OUR SOUTHEAST...IT IS
QUITE IMPRESSIVE. LOW LEVEL AIR TRAJECTORIES SHOW THAT THE AIR IN
THE WARM SECTOR OF THE SYSTEM TO OUR SOUTH CAN BE TRACED BACK TO NOT
JUST THE GULF OF MEXICO...BUT CLEAR DOWN INTO THE NRN CARIBBEAN AND
BACK EAST ACROSS CUBA INTO THE TROPICAL WRN ATLANTIC...HENCE WHY
HISTORIC RAINFALLS ARE EXPECTED IN THE COMING DAYS ACROSS THE OHIO
VALLEY.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 400 AM CST FRI DEC 20 2013
THE ARCTIC FRONT WILL OSCILLATE BACK AND FORTH ACROSS THE FORECAST
AREA DURING THE LONGER TERM. THIS WILL OFFER AT LEAST TWO SNOW
EVENTS AS WAVES OF LOW PRESSURE MOVE THROUGH FROM SUNDAY INTO
MONDAY AND THEN FROM TUESDAY INTO WEDNESDAY. SNOW ACCUMULATIONS OF AN
INCH OR TWO ARE POSSIBLE WITH EACH EVENT. FAIRLY STRONG HIGH
PRESSURE WILL FOLLOW EACH OF THESE WAVES. MONDAY MORNING STILL
LOOKS THE COLDEST WITH LOWS FROM NEAR 20 BELOW IN WEST CENTRAL MN
TO AROUND ZERO AT KEAU. COUPLE THIS WITH NORTHWEST WINDS NEAR 10
MPH AND WIND CHILL READINGS COME OUT TO AROUND 35 BELOW ZERO
ACROSS THE WESTERN CWA. HIGHS ON MONDAY WILL LIKELY STAY BELOW
ZERO ACROSS THE WEST WITH SINGLE DIGITS ABOVE ZERO FOR THE TWIN
CITIES AND WEST CENTRAL WI. A NON-DIURNAL TEMPERATURE TREND WAS
THEN INSERTED FOR MONDAY NIGHT ACROSS WEST CENTRAL AND SOUTHWEST
MN AS SOUTHERLY FLOW INCREASES ON THE BACK SIDE OF THE HIGH AS THE
NEXT WAVE OF LOW PRESSURE MOVES INTO THE DAKOTAS. CENTRAL AREAS OF
MN AND WEST CENTRAL WI WILL STILL HAVE A VERY COLD NIGHT WITH LOWS
MONDAY NIGHT FROM 10 BELOW TO 15 BELOW ZERO. THE WAVE OF LOW
PRESSURE ARRIVING ON TUESDAY POSES SOME PRECIP TYPE PROBLEMS FOR
SOUTHWEST MN WITH THE GFS INDICATING SOME POTENTIAL FOR FREEZING
DRIZZLE/FREEZING RAIN. THE ECMWF IS NOT AS AGGRESSIVE WITH THE LOW
LEVEL WARMING...PARTLY BECAUSE THE WHOLE UPPER WAVE IS FARTHER
SOUTH COMPARED TO THE GFS. THE ECMWF HAS DEEPER SATURATION AS
WELL. POPS FOR THE TUESDAY AND WEDNESDAY PERIOD WILL LIKELY NEED
TO BE ADJUSTED UPWARD IF THE POSITION OF THE GFS GETS CLOSER TO
THE ECMWF. POPS WERE EXPANDED AND ADJUSTED UPWARD FOR THE WAVE
FROM SUNDAY INTO MONDAY AS THE NORTHERN STREAM HAS BECOME
STRONGER. THE OTHER PROBLEM ON SUNDAY TO KEEP AN EYE ON IS THE
BLOWING SNOW FROM WEST CENTRAL INTO SOUTH CENTRAL MN. WITH MORE
WIDESPREAD SNOW FORECAST ALONG WITH INCREASING NORTHWEST WINDS AS
THE NEXT SURGE OF ARCTIC PUSHES IN...SOME PRETTY POOR VISIBILITIES
MAY RESULT ACROSS THE MN RIVER VALLEY DURING THE AFTERNOON AND NIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1026 PM CST THU DEC 19 2013
LITTLE CHANGE TO PREVIOUS THINKING...AT LEAST EARLY ON. BANDING ON
RADAR SHOULD CONTINUE TO TREND SOUTHEAST AS UPPER TROUGH SHEARS TO
THE EAST. WILL CONTINUE SNOW OVER THE EAST OVERNIGHT AND END
AROUND 12Z AS FORCING MOVES OFF. WILL END SNOW FROM NORTHWEST
THROUGH 08Z AS WELL. THEN FOCUS TURNS TO REMAINING CEILING OVER
THE AREA. APPEARS IFR CEILINGS WILL BE GENERATED OVER PARTS OF
CENTRAL CWA WHERE BEST SATURATION OCCURRED. QUESTION REMAINS IF
THIS DEVELOPS FURTHER TO THE SOUTHEAST OVERNIGHT INTO FRIDAY
MORNING. LOW CONFIDENCE ON MVFR CEILING FORECAST OVER THE AREA
INTO FRIDAY. THE SREF MVFR CIG PROBABILITIES REMAIN HIGH THROUGH
THE DAY ESPECIALLY OVER THE EASTERN CWA...AHEAD OF SURFACE RIDGE.
WILL HOLD ONTO THE MVFR CIGS THROUGH THE PERIOD...SIMILAR TO LAMP
GUIDANCE TREND FOR NOW. SURFACE WINDS WILL GRADUALLY TURN MORE
NORTHERLY INTO FRIDAY AND SLACKEN WITH THE APPROACH OF THE SURFACE
HIGH.
KMSP...
BANDED PRECIPITATION PATTERN DIFFICULT TO FORECAST. MODELS
SUGGEST DRYING TREND CONTINUING OVER THE SOUTHERN METRO OVERNIGHT.
STILL BELIEVE WHATEVER SNOW BAND REMAINS OVER THE CENTRAL CWA WILL
WORK SOUTHEAST AND WEAKEN THE REMINDER OF THE NIGHT. SO BELIEVE
MORE SNOW TO WORK ACROSS THE AIRPORT OVERNIGHT. WILL TRAIL IT OFF
AFTER 12Z BUT RETAIN THE MVFR CIGS DURING THE DAY. STILL A QUESTION
OF THESE WILL CLEAR THROUGH THE DAY...SO HELP ONTO THEM FOR NOW. NORTHEAST
TO NORTH WINDS THIS MORNING...WILL GRADUALLY DIMINISH INTO FRIDAY
AS SURFACE RIDGE BUILDS EAST.
/OUTLOOK FOR KMSP/
FRI EVENING...MVFR CIGS PSBL. WNDS LIGHT NW.
SAT...VFR. WNDS SE 5 KTS...BECOMING NW.
SUN...VFR. POSSIBLE MVFR CIGS/VSBYS -SN. WNDS WNW 15-20 KT G25-30KT.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
SHORT TERM...MPG
LONG TERM...RAH
AVIATION...DWE
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
926 AM CST Fri Dec 20 2013
.UPDATE:
Issued at 924 AM CST Fri Dec 20 2013
Strong cold front continues to plod east, a bit slower than going
forecast. Have updated movement to blend with latest RUC guidance,
with an uptick in high temps ahead of the slow moving but strong
thermal gradient. Have also continued mention of light rain near
and ahead of the boundary. Updated zones out in a second.
Truett
&&
.SHORT TERM: (Through Late This Afternoon)
Issued at 421 AM CST Fri Dec 20 2013
The cold front has just passed through KUIN and KMBY at 10z and
will continue to move southward throughout the day, especially as
the surface low now in west central MO lifts by the area.
Temperatures will fall in its wake, with some rise ahead of the
front and values into the lower 60s expected across southern
sections of the CWA. Precipitation thus far has been scattered/spotty
and primarily confined to the warm sector and am anticipating that
to continue.
Glass
.LONG TERM: (Tonight through Thursday)
Issued at 421 AM CST Fri Dec 20 2013
The cold front will become quasi-stationary this evening from the
Ohio Valley through the lower MS valley into the southern Plains.
A strong overunning pattern will become established this evening
as the low level jet provides lift and rich moisture transport
into the cool sector. This coupled with low-mid level frontogenetic
forcing and the development of a coupled ULJ structure later
tonight will result in strong ascent and the northward spread of
precipitation into the cold air. Precipitation will expand even
further north on Saturday as the low-mid level flow backs in response
to the southern stream upper low/trof ejecting northeastward.
Present indications are the southward extent of freezing air will
be greater than previously thought and there will be potential for
a quarter inch and greater of ice accumulation from central MO
into NE MO and west central IL beginning later tonight through the
day on Saturday and into Saturday evening. Complicating the ice
forecast is the freezing line could waver north and south on
Saturday and Saturday evening. As the upper low/trof ejects
rapidly northeastward from western OK across northern MO on
Saturday night it should spread a band of heavy snow from eastern
KS across NW MO into SE IA with northeast Missouri potentially
seeing 2-4 inches on the southern end of this band and the
stronger ascent. A winter storm watch has been issued primarily
for the potential for signficant ice accumulations across the
northeast third of the CWA. Lastly, presistent rain across the
southeast third of the area tonight through Saturday evening is
expected to result in anywhere from 2-4 inches of rainfall which
could bring flooding problems to some of the rivers and small
streams, and lots of standing water. The flood watch continues in
this area.
Glass
&&
.AVIATION: (For the 12z TAFs through 12z Saturday Morning)
Issued at 637 AM CST Fri Dec 20 2013
Cold front is making it way southeast across forecast area today,
then will stall out just south of forecast area. As of 12z, it was
south of KUIN. The front will move through KCOU by 13z and metro
area by 18z-19z timeframe. As front approaches taf sites, cigs to
lower to ifr with scattered light rain and patchy fog. Then
precipitation to taper off by midday most locations, but cigs to
remain ifr through rest of forecast period. Will see another round
of precipitation early this evening and persist through rest of
forecast period for sites along I-70 corridor. For KCOU, the
temperatures will be below freezing so will see some light
freezing rain while metro area to remain above freezing. As for
winds, south winds to veer to the northwest to north behind the
frontal boundary.
Specifics for KSTL:
Cold front is making it way southeast across region today, then will
stall out just south of forecast area. As of 12z, it was south of
KUIN. The front will move through metro area between 18z-19z. As
front approaches KSTL, cigs to lower to ifr with scattered light
rain and patchy fog by 18z. Then precipitation to taper off by
22z, but cigs to remain ifr through rest of forecast period. Will
see another round of precipitation after 01z and remain over area
through rest of forecast period. Temperatures will remain above
freezing tonight so precipitation will be all rain. As for winds,
south winds to veer to the northwest to north behind the frontal
boundary.
Byrd
&&
.HYDROLOGY:
Issued at 407 PM CST Thu Dec 19 2013
Based on this morning`s QPF ensemble from WPC, our 72-hour
contingency forecasts (forecasts based on an uncertain 72 hours of
QPF) indicate the most likely outcomes across the Meramec, Big,
Bourbeuse, Black, and Kaskaskia basins are either minor flooding or
crests a little below flood stage. No flooding is most likely in
basins to the north of I-70. Minor flood crests were indicated
along the upper Meramec River at Steelville and Sullivan and on the
Black River near Annapolis.
Fuchs
&&
.LSX WATCHES/WARNINGS/ADVISORIES:
MO...FLOOD WATCH from 6 PM CST this evening through Saturday evening
FOR Crawford MO-Franklin MO-Gasconade MO-Iron MO-Jefferson
MO-Madison MO-Osage MO-Reynolds MO-St. Charles MO-St.
Francois MO-St. Louis City MO-St. Louis MO-Ste. Genevieve
MO-Warren MO-Washington MO.
WINTER STORM WATCH from 6 PM CST this evening through late
Saturday night FOR Audrain MO-Boone MO-Callaway MO-Cole MO-
Moniteau MO-Montgomery MO.
WINTER STORM WATCH from Saturday morning through late Saturday
night FOR Knox MO-Lewis MO-Marion MO-Monroe MO-Pike MO-
Ralls MO-Shelby MO.
IL...FLOOD WATCH from 6 PM CST this evening through Saturday evening
FOR Bond IL-Clinton IL-Fayette IL-Jersey IL-Macoupin IL-
Madison IL-Marion IL-Monroe IL-Montgomery IL-Randolph IL-
St. Clair IL-Washington IL.
WINTER STORM WATCH from Saturday morning through late Saturday
night FOR Adams IL-Brown IL-Pike IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
915 PM EST SAT DEC 21 2013
.SYNOPSIS...
A STORM SYSTEM WILL MOVE FROM THE MISSISSIPPI RIVER VALLEY TO THE
LOWER GREAT LAKES TONIGHT AND BRING RAIN TO THE REGION. A COLD
FRONT WILL SWING THRU THE AREA BRING DRIER AND SOMEWHAT COOLER AIR
TO THE AREA SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
740 PM UPDATE...
CHALLENGING NEAR TERM FORECAST AS FRONT WAVERS NORTH AND SOUTH IN
ADVANCE OF NORTHEAST MOVING CYCLONE. AREAS NORTHWEST OF THE FRONT
ARE FLIRTING WITH TEMPERATURES IN THE LOWER 30S, WITH FREEZING
RAIN BECOMING A FACTOR.
LATEST NAM12 925MB TEMPERATURE PATTERN SEEMS TO BE VERIFYING
REASONABLY WELL, AND WE USED THIS AS OUR BASIS FOR MOVING THE FRONT
OVER THE NEXT SEVERAL HOURS. BASED ON THIS ANALYSIS, BELIEVE THERE
IS A CHANCE FOR THE COLD AIR TO POUR INTO THE NORTHWESTERN CORNER
OF STEUBEN COUNTY, UP THROUGH WESTERN SENECA COUNTY, BETWEEN 3Z
AND 8Z. THERE IS NOW A SLIGHT CHANCE FOR FREEZING RAIN FOR A SHORT
WINDOW IN THIS AREA.
THEREAFTER THE WARM AIR COMES THROUGH ON A TRUCK...DRIVEN BY
STRONG SOUTHWESTERLY FLOW, AND PUSHING SURFACE TEMPS THROUGH THE
40S AND 50S ACROSS THE REGION FOR EARLY SUNDAY MORNING.
THE OTHER PROBLEM OF THE EVENING IS OBVIOUSLY QPF. HAVE REWORKED
THE 0Z-6Z QPF GRIDS BASED ON LATEST GUIDANCE, AND STAYED PRETTY
MUCH IN LINE WITH HPC FOR 6Z-12Z. THE GFS HAS BEEN ALL OVER THE
MAP THE LAST 24 HOURS, AT ONE TIME BEING AN OUTLIER ON THE HIGH
SIDE OF QPF, AND NOW BEING ON THE LOW SIDE. ITS INCONSISTENCY
GIVES ME LITTLE CONFIDENCE, SO I WEIGHTED IT LOW COMPARED TO THE
NEW NAM12, HRRR, AND RAP PROJECTIONS. IN TOTAL, THE NET EFFECT WAS
A DECREASE IN STORM TOTAL QPF OF ABOUT 0.15 TO 0.30 INCHES. THIS
LOOKS PRETTY GOOD COMPARED WITH UPSTREAM RADAR DEPICTION.
WILL CONTINUE TO ASSESS THE EARLY SUNDAY MORNING QPF SCENARIO.
3 PM UPDATE... COMPLEX SCENARIO FOR THE FCST AS VERY WRM AIR
STREAMS NEWRD TNGT LOADED WITH MOISTURE. MEANWHILE...CONFLUENT UPR
FLOW TRIES TO BLD THE LL COLD OVER NRN NY WITH SFC RDGG. SOME OF
THAT COLDER AIR ALREADY HAS AFFECTED THE FAR NRN ZONES AND SYR
DROPPED 7F IN THE PAST HR. LOOKS LIKE A CLOSE CALL BUT THAT THE
BLO FRZG AIR WILL REMAIN JUST NORTH OF THE FINGER LAKES ZONES THRU
TNGT...BEFORE BEING PUSHED NWRD.
OTR ISSUE IS THE HEAVY RAIN AND SNOW MELT. MODELS CONT TO KEEP THE
AXIS OF HEAVY RAIN GNRLY NORTH OF THE SUSQ BASIN...AND JUST
TOUCHING THE FINGER LAKES. 12 HR QPF LOOS TO BE UNDER 2 INCHES BUT
WITH SNOW MELT...SOME FCST PTS WILL HIT A MINOR FLOOD STAGE
BEGINNING SUNDAY. HAVE XTNDD THE CVRG OF THE WATCH TO INCLUDE ALL
NY COUNTIES XCPT SULLIVAN...AND TWO NRN PA COUNTIES. SEE HYDRO
DISC FOR DETAILS ON THE FLOOD PTNL.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
NO REAL BRK IN THE SHRT TERM AS A GOOD SLUG OF PCPN PASSES WITH A
SFC TROF/COLD FNT ON SUNDAY. GOOD NEWS IS THAT THE PCPN WILL BE
PROGRESSIVE SO THERE WILL HOPEFULLY LTL XTRA EFFECT ON THE RVRS.
FNT STALLS AGAIN...THIS TIME EAST OF THE FCST AREA. HWVR...THERE
IS NO COLD AIR TO SPEAK OF AND AS A WV MVES UP THE MON...MSTLY
RAIN WILL FALL OVER THE ERN ZONES WITH PERHAPS SOME SNOW LATE AS
THE COLD AIR FNLY BEGINS TO ARRIVE. WLD NOT BE SURPIRISED TO SEE
AND INCH OR TWO OF SNOW ON THE BACK SIDE LATE MON. WILL WORRY ABT
THAT LTR.
UPR TROF SETTLES IN WITH SOME SYNOPTIC MOISTURE AND LE SNOWS AS H8
TEMPS APRCH -20C LATE IN THE DAY. FLOW IS RATHER SHEARED EARLY
ON...BUT MAY ALIGN LATE IN THE PD INCRSG ACTIVITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
1 PM EST UPDATE...
FOLLOWED WPC GUIDANCE. GFS AND EURO ARE SIMILAR. COLDER AND DRIER
THAN NORMAL. COLD ENOUGH FOR ALL SNOW BUT AMOUNTS WILL BE MINOR.
MOSTLY IN A BROAD UPPER LEVEL TROF. LINGERING LAKE EFFECT SNOW
IN CENTRAL NY TUES NGT GETS SHUT OFF AS A LARGE SFC HIGH PRESSURE
SITS OVER THE EAST COAST WED AND WED NGT. A DIGGING SHORT WAVE
SINKS SE INTO THE AREA LATE THU AND THU NGT WITH A SFC COLD FRONT.
LAKE EFFECT BEHIND IT FRIDAY BUT LOW LEVEL FLOW SHIFTS TO THE WEST
AND HIGH PRESSURE BUILDS IN SATURDAY.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
00Z UPDATE...
POOR AVIATION CONDITIONS FOR MOST LOCATIONS TONIGHT...WITH SHALLOW
SURFACE BOUNDARY SLIPPING SOUTH TO ABOUT KELM-KBGM AND THUS LOW
CIGS ALONG AND NORTH OF THERE. WAVES OF RAIN ALSO PASSING ALONG
AND NORTH OF THE FRONT. IFR OR WORSE CONDITIONS FOR ALL TERMINALS.
MEANWHILE...SOUTH OF THE FRONT...MOIST SSW WIND AT KAVP ALSO
FAVORABLE FOR DEVELOPMENT OF IFR LATER TONIGHT THROUGH MOST OF
SUNDAY. ANOTHER CONCERN IS FOR LLWS DURING EARLY MORNING HOURS AS
A 50-60 KT JET PASSES AT ABOUT 2 KFT AGL. THE JET DECREASING MID
MORNING ONWARD...BUT RESTRICTIONS FROM IFR CIGS AT LEAST
OCCASIONAL MVFR OR WORSE VIS AS WAVES OF RAIN CONTINUE. SOME
IMPROVEMENT TOWARDS THE END OF THE PERIOD AS FRONT BEGINS TO PASS
THROUGH THE AREA AND WAVE ALOFT REMOVES DEEPER MOISTURE.
OUTLOOK...
SUN NGT-MON...RESTRICTIONS POSSIBLE FROM -SHRA/-SHSN.
TUE AND WED...VFR...WITH ISOLATED MVFR IN -SHSN EARLY.
THU...VFR.
&&
.HYDROLOGY...
9 PM UPDATE...
SEVERAL POINTS ARE FORECAST TO GET INTO MINOR FLOOD STAGE SUNDAY
OR SUNDAY NIGHT...AND LAKELAND OF NINE MILE CREEK EVEN ECLIPSING
MODERATE STAGE. MODEL CONSENSUS IS MORE DECIDEDLY NORTHWEST OF
MOST OF THE AREA FOR THE HIGHEST RAINFALL AMOUNTS...YET DEGREE OF
SNOWMELT IN LAST 12-24 HOURS HAS ALSO BEEN FASTER THAN EXPECTED.
SNOWMELT AND THE ADDITIONAL THREE-QUARTERS OF AN INCH TO INCH-
AND-A-QUARTER OF RAINFALL TONIGHT THROUGH SUNDAY FOR MOST OF THE
FLOOD WATCH AREA /MOST OF CENTRAL NEW YORK AND INTO NORTHERN TIER
PA/ WILL RESULT IN SIGNIFICANT RISES FOR RIVERS. RIVER FORECAST
CENTERS ARE CRUNCHING UPDATED FORECASTS BASED ON OBSERVED AND
EXPECTED RAINFALL ALONG WITH SNOWMELT AND CURRENT STAGES. WE
ANTICIPATE MAKING SOME WARNING DECISIONS LATER THIS EVENING FOR
SEVERAL OF OUR RIVER POINTS...JOINING LAKELAND WITH RIVER FLOOD
WARNING. STILL EXPECTING ACTION STAGE TO SOMEWHERE INTO MINOR
FLOOD STAGE FOR VAST MAJORITY OF AFFECTED RIVER POINTS. MODERATE
STAGES SHOULD BE LIMITED TO ONLY ONE OR TWO SITES. SMALL STREAM
AND STORM DRAIN TROUBLES STILL APPEAR LIKELY ACROSS THE CENTRAL NY
COUNTIES TONIGHT THROUGH SUNDAY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH THROUGH MONDAY MORNING FOR PAZ038-039.
NY...FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ009-015>018-022>025-
036-037-044>046-055>057.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...MDP
HYDROLOGY...MDP
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
745 PM EST SAT DEC 21 2013
.SYNOPSIS...
A STORM SYSTEM WILL MOVE FROM THE MISSISSIPPI RIVER VALLEY TO THE
LOWER GREAT LAKES TONIGHT AND BRING RAIN TO THE REGION. A COLD
FRONT WILL SWING THRU THE AREA BRING DRIER AND SOMEWHAT COOLER AIR
TO THE AREA SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
740 PM UPDATE...
CHALLENGING NEAR TERM FORECAST AS FRONT WAVERS NORTH AND SOUTH IN
ADVANCE OF NORTHEAST MOVING CYCLONE. AREAS NORTHWEST OF THE FRONT
ARE FLIRTING WITH TEMPERATURES IN THE LOWER 30S, WITH FREEZING
RAIN BECOMING A FACTOR.
LATEST NAM12 925MB TEMPERATURE PATTERN SEEMS TO BE VERIFYING
REASONABLY WELL, AND WE USED THIS AS OUR BASIS FOR MOVING THE FRONT
OVER THE NEXT SEVERAL HOURS. BASED ON THIS ANALYSIS, BELIEVE THERE
IS A CHANCE FOR THE COLD AIR TO POUR INTO THE NORTHWESTERN CORNER
OF STEUBEN COUNTY, UP THROUGH WESTERN SENECA COUNTY, BETWEEN 3Z
AND 8Z. THERE IS NOW A SLIGHT CHANCE FOR FREEZING RAIN FOR A SHORT
WINDOW IN THIS AREA.
THEREAFTER THE WARM AIR COMES THROUGH ON A TRUCK...DRIVEN BY
STRONG SOUTHWESTERLY FLOW, AND PUSHING SURFACE TEMPS THROUGH THE
40S AND 50S ACROSS THE REGION FOR EARLY SUNDAY MORNING.
THE OTHER PROBLEM OF THE EVENING IS OBVIOUSLY QPF. HAVE REWORKED
THE 0Z-6Z QPF GRIDS BASED ON LATEST GUIDANCE, AND STAYED PRETTY
MUCH IN LINE WITH HPC FOR 6Z-12Z. THE GFS HAS BEEN ALL OVER THE
MAP THE LAST 24 HOURS, AT ONE TIME BEING AN OUTLIER ON THE HIGH
SIDE OF QPF, AND NOW BEING ON THE LOW SIDE. ITS INCONSISTENCY
GIVES ME LITTLE CONFIDENCE, SO I WEIGHTED IT LOW COMPARED TO THE
NEW NAM12, HRRR, AND RAP PROJECTIONS. IN TOTAL, THE NET EFFECT WAS
A DECREASE IN STORM TOTAL QPF OF ABOUT 0.15 TO 0.30 INCHES. THIS
LOOKS PRETTY GOOD COMPARED WITH UPSTREAM RADAR DEPICTION.
WILL CONTINUE TO ASSESS THE EARLY SUNDAY MORNING QPF SCENARIO.
3 PM UPDATE... COMPLEX SCENARIO FOR THE FCST AS VERY WRM AIR
STREAMS NEWRD TNGT LOADED WITH MOISTURE. MEANWHILE...CONFLUENT UPR
FLOW TRIES TO BLD THE LL COLD OVER NRN NY WITH SFC RDGG. SOME OF
THAT COLDER AIR ALREADY HAS AFFECTED THE FAR NRN ZONES AND SYR
DROPPED 7F IN THE PAST HR. LOOKS LIKE A CLOSE CALL BUT THAT THE
BLO FRZG AIR WILL REMAIN JUST NORTH OF THE FINGER LAKES ZONES THRU
TNGT...BEFORE BEING PUSHED NWRD.
OTR ISSUE IS THE HEAVY RAIN AND SNOW MELT. MODELS CONT TO KEEP THE
AXIS OF HEAVY RAIN GNRLY NORTH OF THE SUSQ BASIN...AND JUST
TOUCHING THE FINGER LAKES. 12 HR QPF LOOS TO BE UNDER 2 INCHES BUT
WITH SNOW MELT...SOME FCST PTS WILL HIT A MINOR FLOOD STAGE
BEGINNING SUNDAY. HAVE XTNDD THE CVRG OF THE WATCH TO INCLUDE ALL
NY COUNTIES XCPT SULLIVAN...AND TWO NRN PA COUNTIES. SEE HYDRO
DISC FOR DETAILS ON THE FLOOD PTNL.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
NO REAL BRK IN THE SHRT TERM AS A GOOD SLUG OF PCPN PASSES WITH A
SFC TROF/COLD FNT ON SUNDAY. GOOD NEWS IS THAT THE PCPN WILL BE
PROGRESSIVE SO THERE WILL HOPEFULLY LTL XTRA EFFECT ON THE RVRS.
FNT STALLS AGAIN...THIS TIME EAST OF THE FCST AREA. HWVR...THERE
IS NO COLD AIR TO SPEAK OF AND AS A WV MVES UP THE MON...MSTLY
RAIN WILL FALL OVER THE ERN ZONES WITH PERHAPS SOME SNOW LATE AS
THE COLD AIR FNLY BEGINS TO ARRIVE. WLD NOT BE SURPIRISED TO SEE
AND INCH OR TWO OF SNOW ON THE BACK SIDE LATE MON. WILL WORRY ABT
THAT LTR.
UPR TROF SETTLES IN WITH SOME SYNOPTIC MOISTURE AND LE SNOWS AS H8
TEMPS APRCH -20C LATE IN THE DAY. FLOW IS RATHER SHEARED EARLY
ON...BUT MAY ALIGN LATE IN THE PD INCRSG ACTIVITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
1 PM EST UPDATE...
FOLLOWED WPC GUIDANCE. GFS AND EURO ARE SIMILAR. COLDER AND DRIER
THAN NORMAL. COLD ENOUGH FOR ALL SNOW BUT AMOUNTS WILL BE MINOR.
MOSTLY IN A BROAD UPPER LEVEL TROF. LINGERING LAKE EFFECT SNOW
IN CENTRAL NY TUES NGT GETS SHUT OFF AS A LARGE SFC HIGH PRESSURE
SITS OVER THE EAST COAST WED AND WED NGT. A DIGGING SHORT WAVE
SINKS SE INTO THE AREA LATE THU AND THU NGT WITH A SFC COLD FRONT.
LAKE EFFECT BEHIND IT FRIDAY BUT LOW LEVEL FLOW SHIFTS TO THE WEST
AND HIGH PRESSURE BUILDS IN SATURDAY.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
1230 PM EST UPDATE...
STILL MOSTLY VFR AT ISSUANCE BUT THIS WILL CHANGE QUICKLY AS A
LARGE AREA OF RAIN MOVES IN FROM THE WSW BY 20Z. CIGS AND VSBYS
WILL FALL TO MVFR BY 21Z WITH THIS RAIN. BY 00Z CIGS SHOULD BE
DOWN TO IFR AND BELOW 1K FT. AVP WILL BE ABOUT 2 HOURS BEHIND THE
NY TERMINALS WITH THE MAIN AXIS OF RAIN IN UPSTATE NY AND NW PA.
RAIN...IFR CIGS AND MVFR VSBYS WILL CONTINUE ALL NIGHT THROUGH AT
LEAST MIDDAY SUNDAY.
WITH A STATIONARY FRONT JUST TO THE NORTH OF SYR AND RME WINDS
WILL BE MOSTLY S TO SW AT LESS THAN 10 KTS. RME IN A WEST EAST
VALLEY WILL BE LIGHT AND VARIABLE.
OUTLOOK...
SUN...MVFR/IFR RESTRICTIONS LIKELY WITH LWR CIGS/-RA/BR.
SUN NGT-MON...RESTRICTIONS POSSIBLE FROM -SHRA/-SHSN.
TUE AND WED...VFR...WITH ISOLATED MVFR IN -SHSN EARLY.
THU...VFR.
&&
.HYDROLOGY...
SATURDAY MORNING UPDATE...STRONG SPRING LIKE STORM WAS APPROACHING
THE AREA TODAY AND RAIN WILL BECOME HEAVIER TONIGHT. STILL SOME
DISCREPANCY IN PLACEMENT OF AXIS OF HEAVY RAIN...HOWEVER CONSENSUS
OF LATEST MODEL QPF FORECASTS SUGGEST THAT SOME OF OUR RIVERS
COULD REACH FLOOD LEVEL ON WHAT IS EXPECTED TO FALL ANYWAY.
CONFIDENCE IN THAT HAS INCREASED A BIT TODAY AS WE HAVE ALREADY
NEARLY MELTED OFF ALL EXISTING SNOW PACK AND RESPONSE HAS BEGUN.
SEVERAL OF THE USUAL TROUBLE RIVER POINTS IN THE UPPER SUSQUEHANNA
AND IT/S TRIBUTARIES ARE SIMULATED TO MINOR FLOODING WITH CRESTS
LATER SUNDAY INTO MONDAY. THERE IS STILL AMPLE TIME TO WAIT WITHIN
THE FLOOD WATCH /WHICH WAS EXPANDED SOUTH EARLIER THIS MORNING/
BEFORE PULLING THE WARNING TRIGGER UNTIL WE SEE THE RAIN AXIS SET
UP. THOSE DECISIONS WILL COME LATER TODAY OR TONIGHT.
SMALL STREAM AND STORM DRAIN TROUBLES SEEM PRETTY LIKELY ACROSS
THE CENTRAL NY COUNTIES TONIGHT AND SUNDAY...AND PRELIMINARY
PRECAUTIONS SHOULD BE TAKEN AT THIS TIME.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH THROUGH MONDAY MORNING FOR PAZ038-039.
NY...FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ009-015>018-022>025-
036-037-044>046-055>057.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...TAC
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS RALEIGH NC
111 AM EST FRI DEC 20 2013
.SYNOPSIS...SOUTH SOUTHWEST FLOW AROUND BERMUDA HIGH PRESSURE WILL
RESULT IN WARMING CONDITIONS THROUGH SUNDAY...FOLLOWED BY THE
PASSAGE OF A COLD FRONT SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /TONIGHT/...
AS OF 940 PM THURSDAY...
THE SURFACE HIGH IS NOW WELL OFF OF THE NC COAST THIS EVENING...WITH
A LIGHT SOUTH-SOUTHWESTERLY WIND AT MOST OBSERVING SITES.
ALOFT...CIRRUS CONTINUES TO SPREAD EAST ACROSS THE REGION...THOUGH
THERE IS CURRENTLY A PATCH OF CLEARING ACROSS THE SOUTHERN PIEDMONT.
THE CIRRUS IS MAKING THE LOW TEMP FORECAST A LITTLE TRICKY..WITH
HIGHLY VARIABLE OBSERVED TEMPS RANGING FROM THE UPPER 30S TO LOWER
50S. WITH MORE CIRRUS IMMEDIATELY UPSTREAM OVER THE TN
VALLEY...TEMPS SHOULD BE VERY SLOW TO FALL FOR THE REMAINDER OF THE
NIGHT. MOST GUIDANCE SEEMS TOO LOW OVERALL BASED ON CURRENT
TRENDS...SO HAVE MADE SOME ADJUSTMENTS TO TRY TO CAPTURE WARMER
READINGS NORTH AND WEST WHERE CIRRUS SHOULD MOST PREVALENT. THE
CIRRUS MAY ALSO LIMIT STRATUS DEVELOPMENT IN THE WEAK RETURN FLOW
THAT HAS DEVELOPED. THE RAP IS MOST AGGRESSIVE WITH THE STRATUS BUT
APPEARS TO HAVE TRENDED LATER AND MORE PATCHY....FOCUSED MOSTLY
ACROSS THE SOUTHERN COASTAL PLAIN. LOWS 37-44.
&&
.SHORT TERM /FRIDAY AND FRIDAY NIGHT/...
AS OF 225 PM THURSDAY...
THE MAIN WEATHER PLAYERS FOR FRIDAY WILL BE THE LONG WAVE TROUGH
MOVING ACROSS THE ROCKIES AND SW STATES...AND A LENGTHY DRAWN-OUT
SFC FRONTAL SYSTEM THAT IS EXPECTED TO EXTEND FROM THE NEW ENGLAND
STATES...SOUTHWEST ACROSS THE MIDWEST...AND SOUTH ACROSS TEXAS.
ACROSS OUR AREA HOWEVER...HIGH PRESSURE CENTERED OVER THE WRN
ATLANTIC WILL CONTINUE TO INFLUENCE OUR WEATHER...PROVIDING FAIR
WEATHER AND WARMER TEMPERATURES AS LOW LEVEL SW FLOW CONTINUES TO
ADVECT WARMER AIR AND ADDITIONAL MOISTURE INTO OUR AREA. AS SUCH...
LOOK FOR PARTIAL SUNSHINE THROUGH A VEIL OF HIGH CLOUDS (AFTER ANY
MORNING LOW CLOUDS AND FOG BURN OFF)...BUT THE MAIN WEATHER STORY
WILL BE THE WARMER TEMPS...AS INCREASING LOW LEVEL THICKNESS VALUES
AND BL WARMING PER LATEST FORECAST SOUNDINGS SUGGEST EARLY-
SPRING-LIKE HIGHS IN THE MID-UPPER 60S.
WITH LITTLE CHANGE IN THE PATTERN FRIDAY NIGHT...LOOK FOR ADDITIONAL
PATCHY LOW CLOUDS AND FOG TO FORM TOWARD SUNRISE SATURDAY...AND LOW
TEMPS 15+ DEGREES ABOVE NORMAL...UPR 40S TO AROUND 50.
STRONG WARM AIR AND MOISTURE ADVECTION WILL CONTINUE AHEAD OF AN
APPROACHING COLD FRONT ON SATURDAY. HIGH CLOUDINESS WILL BE
WIDESPREAD...BUT EVEN MILKY SUN WILL ALLOW HIGHS TO SOAR INTO THE
UPPER 60S TO MID 70S WHICH SHOULD ECLIPSE RECORD HIGHS FOR THE 21ST
FOR RDU AND GSO...LISTED BELOW. AS THE FRONT CREEPS UP TO THE
WESTERN SLOPES...SCATTERED SHOWERS ARE EXPECTED IN THE WESTERN
PIEDMONT LATER SATURDAY NIGHT. ONGOING WARM FLOW AND CLOUD COVERAGE
WILL PRODUCE A VERY MILD NIGHT...WITH LOWS IN THE UPPER 50S TO
PERHAPS EVEN LOW 60S...WHICH ARE HIGHER THAN CLIMATOLOGICAL MAX
TEMPS FOR THE DATE.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AS OF 255 PM THURSDAY...
UPPER SHORT WAVE IS WELL OFF TO THE NORTHWEST OVER THE UPPER MID
WEST AND THE FRONT WILL BE STRETCHED/SHEARED MORE PARALLEL TO THE
MID AND UPPER FLOW...SO THERE IS NOT INITIALLY STRONG DRIVING FORCES
TO PROPEL THE FRONT EAST. THE LATEST GFS HAS NONETHELESS SPED UP
EASTWARD PROGRESSION ACROSS THE AREA LATE SUNDAY. WILL MAINTAIN A
SLOWER ECMWF TIMING...WITH LIKELY POPS IN THE FAR WESTERN PIEDMONT
LATE IN THE DAY...AND ONLY SMALL CHANCES IN THE EAST. THERE WILL BE
A STRONG LOW LEVEL JET (EXCEEDING 50KT AT H92-H85) WITH DIFFLUENT
FLOW ALOFT...SO ISOLATED THUNDER WILL BE MAINTAINED DESPITE WEAK
INSTABILITY. HIGHS WILL AGAIN APPROACH OR EXCEED RECORDS...WITH MOST
AREAS REACHING MID AND UPPER 70S.
LIKELY POPS EXPECTED SUNDAY NIGHT IN THE WEST...TRANSITIONING TO THE
EAST ON MONDAY AS THE FRONT SLOWS AND MODELS COME MORE IN ALIGNMENT
WITH A POSITION OVER THE COASTAL PLAIN BY MONDAY EVENING.
AGAIN...STRONG LOW LEVEL FORCING AND UPPER DYNAMICS SHOULD PRODUCE
ENOUGH LIFT FOR ISOLATED THUNDER. HIGHS MONDAY WILL BE LEVELING OFF
BY AFTERNOON IN THE WEST AFTER MAXING OUT IN THE UPPER 50S...
MEANWHILE...THE EAST WILL REACH THE MID AND UPPER 60S BEFORE THE
COLD AIR ADVECTION KICKS IN BEHIND THE FRONT. PRECIP WILL TAPER OFF
BY MIDNIGHT IN THE EAST...WITH DRIER AND COOLER AIR SURGING INTO THE
AREA MONDAY NIGHT...LOWS WILL BE IN THE 30S...WITH THE NORTHWEST
FALLING BELOW FREEZING.
HIGH PRESSURE WILL DOMINATE TUESDAY THROUGH THURSDAY...PROVIDING US
WITH COOL...BUT SEASONABLE TEMPERATURES THROUGH THE CHRISTMAS
HOLIDAY. TUESDAYS HIGHS WILL BE IN THE 40S...WITH 45 TO 50 DEGREES
EXPECTED ON CHRISTMAS DAY AFTER A MORNING LOW IN THE MID TO UPPER
20S. COOL AIR WILL BE LOOSENING ITS GRIP IN THE LATE WEEK...WITH AN
INVERTED TROF SETTING UP ALONG THE COAST TO PROVIDE INCREASED
CLOUDINESSS IN THE SOUTH AND EAST. HIGHS THURSDAY ARE LOW CONFIDENCE
AT THIS POINT...50 TO 55 LOOKS REASONABLE AT THIS POINT.
&&
.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AS OF 110 AM THURSDAY...
RETURN FLOW AROUND BERMUDA HIGH PRESSURE WILL RESULT IN CONTIUED LOW
LEVEL MOISTENING OF THE VERY DRY ANTECEDENT AIR MASS...AND THIS MAY
LEAD TO SOME LOW STRATUS (LOW TO MEDIUM CONFIDENCE) GENERALLY IN THE
LOW END MVFR/IFR RANGE BY AROUND DAYBREAK AT KGSO/KINT AND POSSIBLY
KFAY (MAYBE MORE VISBY RESTRICTIONS AT FIRST AT KFAY). CANT RULE OUT
SOME BRIEF SUB VFR CONDITIONS AT KRDU AND KRWI AS WELL. EXPECT ANY
LOW STRATUS AND/OR FOG WILL MIX OUT BY 16/17Z AT THE LATEST. VFR
CONDITIONS ARE THEN EXPECTED TO CONTINUE FOR THE REMAINDER OF THE
TAF PERIOD. HOWEVER... WE WILL LIKELY SEE SUSTAINED WINDS DURING
FRIDAY AFTERNOON IN THE 10 TO 15 MPH RANGE... WITH GUSTS POSSIBLE IN
THE 20 TO 25 MPH RANGE.
LOOKING AHEAD: WARM/MOIST SOUTHERLY RETURN FLOW WILL INCREASE ACROSS
THE CAROLINAS THROUGH SUNDAY NIGHT. LOW STRATUS WILL BE POSSIBLE
MAINLY EACH MORNING...FOLLOWED BY NUMEROUS SHOWERS WITH THE PASSAGE
OF A COLD FRONT SUNDAY NIGHT AND MONDAY.
&&
.CLIMATE...
AS OF 230 PM WEDNESDAY...
DAILY RECORDS FOR SATURDAY/SUNDAY DECEMBER 21/22 ARE AS FOLLOWS:
RALEIGH/DURHAM...
HIGHHI MIN
DECEMBER 21... 71 DEGREES...SET IN 196759 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 196761 DEGREES...SET IN 2011
--------------------------------------------------------------------
GREENSBORO...
HIGHHI MIN
DECEMBER 21... 66 DEGREES...SET IN 192355 DEGREES...SET IN 1984
DECEMBER 22... 71 DEGREES...SET IN 192360 DEGREES...SET IN 2011
--------------------------------------------------------------------
FAYETTEVILLE...
HIGHHI MIN
DECEMBER 21... 77 DEGREES...SET IN 193160 DEGREES...SET IN 1923
DECEMBER 22... 75 DEGREES...SET IN 201160 DEGREES...SET IN 2011
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE
&&
$$
SYNOPSIS...26
NEAR TERM...NP/SMITH
SHORT TERM...NP
LONG TERM...MLM
AVIATION...26
CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS PORTLAND OR
321 AM PST FRI DEC 20 2013
.SYNOPSIS...LIGHT SNOW IS BEGINNING TO MOVE INTO WASHINGTON EARLY
THIS MORNING...AND IS EXPECTED TO SPREAD SOUTHWARD AND INLAND INTO
THE FORECAST AREA OVER THE NEXT FEW HOURS. THIS IS ASSOCIATED WITH A
WARM FRONT AND ONSHORE FLOW DEVELOPING OVER THE COLD AIR MASS THAT IS
ALREADY IN PLACE. EVENTUALLY...ENOUGH MILD PACIFIC AIR WILL MOVE IN
ALOFT TO CHANGE PRECIPITATION TO A BRIEF PERIOD OF SLEET OR FREEZING
RAIN THEN ALL RAIN FOR MOST AREAS BY MIDDAY. RAIN WILL CONTINUE INTO
TONIGHT...THEN DECREASE INTO SATURDAY. NORTHWEST FLOW ALOFT WILL KEEP
A CHANCE FOR RAIN THROUGH THE WEEKEND. A GULF OF ALASKA COLD FRONT
WILL BRING MORE ORGANIZED RAIN TO THE DISTRICT MONDAY... FOLLOWED BY
DRIER WEATHER FOR THE REST OF THE WEEK.
&&
.SHORT TERM...TODAY THROUGH SUNDAY...A NAILBITER OF A FORECAST THIS
MORNING...WITH POTENTIAL FOR A WINTRY MIX OF PRECIPITATION TO IMPACT
THE MORNING COMMUTE FOR A LARGE PORTION OF SOUTHWEST WASHINGTON AND
NORTHWEST OREGON. EVEN WITH PRECIPITATION EXPECTED TO ARRIVE WITHIN
THE NEXT FEW HOURS...QUESTIONS REMAIN REGARDING THE PREDOMINANT
PRECIPITATION TYPE THIS MORNING.
RADAR AND SURFACE OBSERVATIONS...AS WELL AS SOME WEBCAMS ARE
INDICATING LIGHT SNOW SPREADING ONSHORE INTO WASHINGTON AS A WARM
FRONT APPROACHES THE COAST. ISENTROPIC LIFT IS BEGINNING TO INCREASE
JUST OFFSHORE OF OUR FORECAST AREA...WITH RADAR ECHOES COMING CLOSE
TO THE PACIFIC COUNTY COAST. EXPECT LIGHT PRECIPITATION WILL BEGIN
WITHIN THE NEXT HOUR OR TWO THERE...THEN SPREAD INLAND AND SOUTH INTO
OREGON BY SUNRISE.
TEMPERATURES ARE GENERALLY RIGHT AROUND FREEZING FOR ALL BUT THE
IMMEDIATE COAST. TEMPS HAVE CREPT UP SLIGHTLY ACROSS THE PORTLAND AND
VANCOUVER METRO AREA AFTER A QUICK DROP BELOW FREEZING EARLIER IN THE
EVENING. KPTV TOWER TEMPS REMAIN ALL BELOW FREEZING...HOWEVER WE HAVE
REACHED 33 DEGREES HERE AT THE OFFICE IN PARKROSE AND MOST OF
DOWNTOWN PORTLAND/VANCOUVER IS 33-34 DEGREES. HOWEVER OUTLYING AREAS
OF BOTH PORTLAND AND VANCOUVER REMAIN IN THE 30-32 DEGREE RANGE AS
PRECIPITATION APPROACHES. MUCH COLDER TEMPS EXIST IN THE CASCADE
VALLEYS...WHICH WILL COME INTO PLAY AS PRECIPITATION ARRIVES
ESPECIALLY FOR THE SOUTH WASHINGTON CASCADES.
00Z UW WRF-GFS SOUNDINGS AND LATEST HRRR PRECIPITATION-TYPE
ALGORITHMS ALL SUGGEST ENOUGH OF A WET BULB EFFECT WILL OCCUR TO
CAUSE PRECIPITATION TO START OFF AS SNOW AS IT ARRIVES EARLY THIS
MORNING. SIGNIFICANT SNOW IS LESS LIKELY SOUTH OF PORTLAND SIMPLY
BECAUSE PRECIPITATION WILL BE LIGHTER TO NON-EXISTENT DURING THE
FIRST FEW HOURS OF THIS MORNING. AREAS SALEM NORTHWARD STAND A CHANCE
TO SEE AT LEAST SOME FLAKES IN THE AIR DURING THE MORNING
COMMUTE...BUT THE BEST CHANCE FOR ACCUMULATING SNOW WILL BE NORTH OF
THE COLUMBIA RIVER. MOST MODELS ARE SHOWING 0.10-0.20 INCH OF QPF
ACROSS SW WASHINGTON THIS MORNING WITH AMOUNTS DROPPING OFF TO THE
SOUTH. THIS WOULD RESULT IN A QUICK 1-2 INCHES OF SNOW DURING THE
MORNING COMMUTE...MAINLY NORTHERN CLARK COUNTY AND AREAS NORTH.
DECIDED TO ISSUE A WINTER WX ADVISORY FOR THE GREATER VANCOUVER METRO
AREA...LOWER COLUMBIA AND I-5 CORRIDOR IN COWLITZ CO AS A
RESULT...BUT WE LEFT THE NORTH WILLAMETTE VALLEY ZONE OUT OF IT AS
ACCUMULATIONS ARE EXPECTED TO BE LESS THAN AN INCH BEFORE CHANGEOVER.
SNOW SHOULD ARRIVE IN KELSO-LONGVIEW BETWEEN 4-430 AM...THEN SPREAD
INTO CLARK COUNTY BY 530 AM. LOOKING AT INFRARED IMAGERY IT APPEARS A
MORE SUBSTANTIAL BATCH OF PRECIPITATION EXTENDS SW FROM
QUILLAYUTE...THIS WILL BE WHAT EVENTUALLY MAKES IT EAST OF THE COAST
RANGE AS IT PUSHES SOUTHEAST. OBVIOUSLY...WILL NEED TO WATCH THIS
BAND CLOSELY FOR THE PORTLAND AREA AS WELL. THERE MAY BE A BRIEF MIX
OF SNOW AND RAIN BEFORE WET-BULBING TURNS PRECIP OVER TO SNOW.
MODELS ARE UNANIMOUS IN PUSHING A MID-LEVEL WARM FRONT QUICKLY
THROUGH THE FORECAST AREA BETWEEN 7-9 AM...WHILE THE SURFACE FRONT
WILL TAKE LONGER. THIS WILL RESULT IN A TRANSITION TO SLEET AND
RAIN...WITH FREEZING RAIN LIKELY IN THE MOST SHELTERED VALLEYS. SNOW
LEVELS WILL SHOOT UP TO 5000-7000 FEET ALMOST INSTANTLY BEHIND THE
MID-LEVEL FRONT.
DUE TO THE MOUNTAIN VALLEY FREEZING RAIN THREAT WE ALSO EXPANDED THE
WINTER WEATHER ADVISORY INTO THE S WA CASCADES. ALSO CONCERNED ABOUT
THE NEHALEM RIVER VALLEY SO WE INCLUDED THE NORTH OREGON COAST RANGE.
THE GREATEST ICE ACCUMULATIONS WILL PROBABLY BE IN THE WIND RIVER AND
UPPER HOOD RIVER VALLEYS...WHERE COLD AIR WILL REMAIN LOCKED IN THE
LONGEST. A COUPLE SPOTS COULD GET A QUARTER INCH OF ICE...BUT MOST
SHOULD SEE ONE TENTH OF AN INCH OR LESS. THE BROADER INTERIOR
LOWLANDS SUCH AS THE WILLAMETTE VALLEY WILL PROBABLY NOT SEE
SIGNIFICANT ICE ACCUMULATIONS EXCEPT PERHAPS A FEW POCKETS IN
NORTHERN CLARK COUNTY LIKE YACOLT.
EVERYTHING SHOULD CHANGE TO PLAIN RAIN MOST AREAS BY 10 AM...WITH ANY
LINGERING POCKETS OF FREEZING RAIN LIKELY ENDING IN THE CASCADE
VALLEYS AND CENTRAL GORGE BY MID AFTERNOON. DECIDED TO SHORTEN THE
ADVISORIES FOR THE CENTRAL GORGE AND UPPER HOOD RIVER VALLEY FOR THIS
REASON.
ONCE PRECIPITATION CHANGES TO RAIN...THIS WILL JUST BE A TYPICAL
DECENT RAIN EVENT FOR MUCH OF THE AREA WITH 1 TO 2 INCHES ALONG THE
COAST AND IN THE HIGHER TERRAIN AND ABOUT 0.5 INCH IN THE VALLEYS
BEFORE PRECIPITATION EASES LATER FRIDAY NIGHT. SOUTH WINDS WILL BE
BREEZY THIS AFTERNOON WITH GUSTS 25-35 MPH IN THE LOWLANDS.
MOISTURE WILL CONTINUE RIDING OVER THE UPPER RIDGE AND INTO THE
PACIFIC NORTHWEST THROUGH THE WEEKEND...BUT THE MOISTURE WILL BE LESS
ORGANIZED. THUS EXPECTED MAINLY SOME OCCASIONAL LIGHT RAIN ESPECIALLY
OVER THE NORTHERN FORECAST ZONES THROUGH THE WEEKEND. TEMPS REMAIN
REASONABLY MILD FOR THIS TIME OF YEAR. PERHAPS A BIT OF NIGHT AND
MORNING FOG...ESPECIALLY SOUTH VALLEY AREAS. THE NEXT FRONT IS LATE
MONDAY AND MONDAY NIGHT. WEAGLE
.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS.
SUNDAY NIGHT THROUGH CHRISTMAS DAY...UPPER LEVEL RIDGING OVER THE
EPAC WILL DOMINATE MUCH OF THE EXTENDED FORECAST. THIS WILL CONTINUE
GENERAL NORTHWESTERLY UPPER LEVEL FLOW THROUGH THE PERIOD...AND
PREVENT ANY SUBSTANTIAL SYSTEMS FROM AFFECTING THE AREA. WEAK WARM
FRONT EXITS SUNDAY NIGHT AND IS FOLLOWED BY A DECAYING COLD FRONT ON
MONDAY. THE COLD FRONT WILL WEAKEN AS IT MOVES INLAND...THEREFORE
EXPECT PRECIP TO GENERALLY REMAIN CONFINED TO THE MORE NORTHERN
AREAS OF THE CWA. TUESDAY THE UPPER RIDGE SHIFTS EAST A BIT...
PLACING THE RIDGE AXIS OVER THE PAC NW BY WEDNESDAY. EXPECT
INCREASINGLY DRY AND COOL CONDITIONS FOR CHRISTMAS EVE ONWARD.
BURGESS
&&
.AVIATION...BRIEF LOCAL MVFR AND IFR LOW STRATUS/FOG WILL PERSIST
FOR INLAND SITES THE NEXT FEW HOURS UNTIL PRECIP AND MID LEVEL
CLOUDS SPREADS INLAND. LIGHT SNOW BEING REPORTED EARLY THIS
MORNING AT KUIL...SO STILL EXPECTING THE THREAT FOR SNOW TO BEGIN
AROUND 12Z-14Z...FOLLOWED BY RAIN/SLEET/FREEZING RAIN MIX. IT
WILL BE A QUICK TRANSITION TO SOLID RAIN AROUND 18Z-20Z THIS
MORNING ONCE S WINDS BEGIN TO WARM THE AIR MASS. MIX OF VFR AND MVFR
CONDITIONS WITH CIGS AROUND 3K FT WILL PREVAIL AFTER 20Z THROUGH
LATE TONIGHT IN RAIN AND ABOVE FREEZING TEMPERATURES.
KPDX AND APPROACHES...MAIN THREAT FOR SNOW ARRIVES AROUND 13Z-14Z
THIS MORNING WITH IFR CONDITIONS POSSIBLE...TRANSITIONING TO A
SNOW/SLEET/RAIN MIX BY 16Z. WARMER AIR ALOFT AND S WINDS WILL
BEGIN TO WARM AIR MASS BY 18Z AT THE LATEST. MVFR CIGS IN SOLID
RAIN WILL CONTINUE AFTERWARDS. /27
&&
.MARINE...RATHER QUIET CONDITIONS THROUGH EARLY THIS MORNING THEN
EXPECT INCREASING WINDS AND SEAS TODAY AND TONIGHT WITH AN
APPROACHING FRONT. SOUTH WINDS WILL INCREASE LATER THIS MORNING
WITH SOLID GUSTS 20-25 KTS. POST FRONTAL GALE FORCE GUSTS TO 35
KT CAN BE EXPECTED MUCH OF TODAY...MADE THE DECISION TO ISSUE A
GALE WARNING FOR GUSTS ACROSS THE WATERS DUE TO THE TIME OF DAY
THE GUSTS WILL IMPACT THE WATERS SINCE THERE MAY BE INCREASED
ACTIVITY. IT WILL BE A MARGINAL EVENT...BUT MODELS ARE SUGGESTING
MORE FREQUENT GUSTS THAN PREVIOUS RUNS. /27
WINDS TURN TO HARD WEST IN THE AFTERNOON AS THE FRONT PUSHES
INLAND...BUT GUSTY WINDS WINDS CONTINUE. SEAS WILL BE ON THE
REBOUND TODAY...BACK ABOVE 10 FT BY LATER THIS MORNING. SEAS WILL
PUSH TO 11 TO 14 FT BY THIS EVENING...WITH HIGHEST OVER THE OUTER
N WATERS. UNSETTLED WEATHER CONTINUES INTO NEXT WEEK...WITH SEAS
RUNNING NEAR 10 FT OR HIGHER AT TIMES. ROCKEY.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL 2 PM PST THIS AFTERNOON FOR UPPER
HOOD RIVER VALLEY.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR CENTRAL
COLUMBIA RIVER GORGE-WESTERN COLUMBIA RIVER GORGE.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR COAST
RANGE OF NORTHWEST OREGON-LOWER COLUMBIA.
WA...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR CENTRAL
COLUMBIA RIVER GORGE-WESTERN COLUMBIA RIVER GORGE.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR
GREATER VANCOUVER AREA.
WINTER WEATHER ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR SOUTH
WASHINGTON CASCADE FOOTHILLS-SOUTH WASHINGTON CASCADES.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR I-5
CORRIDOR IN COWLITZ COUNTY.
PZ...GALE WARNING FROM 9 AM THIS MORNING TO 7 PM PST THIS EVENING
FOR COASTAL WATERS FROM CAPE SHOALWATER TO FLORENCE OUT 60 NM.
SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 3 PM
THIS AFTERNOON TO 9 PM PST THIS EVENING.
&&
$$
MORE WEATHER INFORMATION ONLINE AT..
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
WWW.TWITTER.COM/NWSPORTLAND
THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON FROM
THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS COMMONLY
REFERRED TO AS THE FORECAST AREA.
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1138 AM CST FRI DEC 20 2013
.UPDATE...
UPDATED AVIATION DISCUSSION BELOW FOR 18Z TAFS.
MADE SOME CHANGES TO THE FORECAST THIS MORNING...MAINLY TO
INCREASE CLOUD COVER THROUGH THE REST OF THE DAY. SURPRISINGLY
TEMPERATURES HAVE BEEN ABLE WARM AS EXPECTED WITH MANY LOCATIONS
CLIMBING ABOVE ZERO. BASED ON THE RAP HAVE MADE SOME MINOR CHANGES
TO THE HIGH TEMPERATURE TODAY.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SUNDAY
THE MODELS SHOW VERY GOOD AGREEMENT THROUGH THE SHORT TERM WITH
COLD NORTHWEST FLOW ALOFT DOMINATING. ABR RADAR WAS SHOWING SOME
WEAK ECHOES EARLY THIS MORNING ALONG WITH FLURRIES REMAINING IN
SOME OBS. THUS...ADDED IN SOME SCATTERED FLURRIES INTO THE
FORECAST. OTHERWISE... ARCTIC HIGH PRESSURE EARLY THIS MORNING
WILL DESCEND SLOWLY SOUTHEAST ACROSS THE REGION TODAY AND THIS
EVENING. WINDS WILL TURN FROM NORTH TO LIGHT SOUTH TO SOUTHWEST
TODAY. WITH THE MOSTLY SUNNY SKIES TODAY/LOW SUN ANGLE OVER FRESH
SNOW COVER ALONG WITH LITTLE WIND...TEMPERATURES WILL STRUGGLE TO
RISE TO TODAY. EXPECT SINGLE DIGITS FOR HIGHS WITH MAYBE SOME
LOWER TEENS SOUTHWEST. WITH LITTLE RISE IN TEMPERATURES TODAY OVER
THE NEW COVER...TEMPERATURES SHOULD FALL QUICKLY THIS EVENING WITH
LITTLE IF ANY CLOUD COVER THROUGH LATE TONIGHT. COULD SEE SOME
TEENS BELOW ZERO EAST IN THE CWA WITH LIGHT SOUTH WINDS. THE
MODELS THEN SHOW GOOD AGREEMENT WITH A SHORT WAVE TROUGH FROM THE
NORTHWEST ALONG WITH ANOTHER ARCTIC BOUNDARY MOVING ACROSS THE
REGION SATURDAY THROUGH SUNDAY. SATURDAY WILL BE ANOTHER COLD DAY
AS MID AND HIGH LEVEL CLOUDS WILL BE SPREADING IN WITH THE NEXT
SYSTEM ALONG WITH A WIND CHANGE TO THE NORTH. DEPENDING ON THE
OVERNIGHT LOWS...TEMPERATURES WILL AGAIN STRUGGLE TO REACH 10 TO
15 DEGREES ACROSS MOST OF THE CWA BY LATE AFTERNOON SATURDAY.
THE MODELS THEN SHOW SOME LIGHT QPF WITH THE SHORT WAVE TROUGH AND
CAA COMING THROUGH SATURDAY NIGHT AND SUNDAY. THIS LOOKS REASONABLE
AND PUT IN SOME POPS FOR THIS TIME PERIOD FOR LIGHT SNOW. ANOTHER
ARCTIC HIGH PRESSURE AREA WILL BUILD INTO THE REGION ON SUNDAY.
AFTER ANOTHER BITTER COLD NIGHT ON SATURDAY NIGHT...TEMPERATURES
IN THE SINGLE DIGITS BELOW ZERO WILL STRUGGLE TO REACH ZERO IN
THE EASTERN CWA WITH ZERO TO 5 ABOVE WEST IN THE CWA ON SUNDAY.
925MB TEMPERATURES WILL FALL TO -18 TO -22C BY 00Z MONDAY. WITH
THE CAA AND 925MB WINDS OF 10 TO 25 KNOTS...WE COULD ALSO HAVE
SOME ADVISORY TYPE WIND CHILLS ON SUNDAY. GENERALLY LOWERED
TEMPERATURES SOME THROUGH THE ENTIRE PERIOD.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
THE EXTENDED IS STILL CHARACTERIZED BY NORTHWEST FLOW AND BELOW
NORMAL COLD AIR. 00Z GLOBAL SPECTRAL MODEL SOLUTIONS WOULD HAVE
ONE BELIEVING THAT SEVERAL PIECES OF S/W ENERGY ARE STILL WORKING
THROUGH THE REGION BETWEEN TUESDAY AND THURSDAY...WITH CHANCES FOR
LIGHT SNOW /LOW ACCUM POTENTIAL/ OFF AND ON ACROSS THE REGION.
TIMING/PLACEMENT DIFFERENCES IN THE MODELS AND SLIGHT DIFFERENCES
IN THERMAL PROGS MADE ACCEPTING THE ALLBLEND GUIDANCE THIS MORNING
AN EASY CHOICE.
&&
.AVIATION...
18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
MVFR/IFR CIGS WILL CONTINUE TO AFFECT KABR/KATY THROUGH THE
AFTERNOON HOURS. EXPECTING TO SEE THESE CIGS ERODE/MOVE OUT OF
KABR BY LATE AFTERNOON AND OUT OF KATY BY LATER THIS EVENING.
OVERNIGHT...MOSTLY VFR CONDITIONS ARE FORECAST AT THIS TIME...BUT
UNFORTUNATELY NOT A LOT OF CONFIDENCE IN THIS. THERE ARE SOME
SUGGESTIONS THAT PATCHES OF MVFR CIGS COULD BE AFFECTING THE
AREA...AND CANNOT COMPLETELY RULE OUT FG/BR OVERNIGHT AS WELL.
WITH THE LOW CONFIDENCE...HAVE NOT INCLUDED IN TAFS AT THIS TIME
AND WILL CONTINUE TO MONITOR.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...SD/TMT
SHORT TERM...MOHR
LONG TERM...DORN
AVIATION...TMT
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
1059 AM CST FRI DEC 20 2013
.UPDATE...
MADE SOME CHANGES TO THE FORECAST THIS MORNING...MAINLY TO
INCREASE CLOUD COVER THROUGH THE REST OF THE DAY. SURPRISINGLY
TEMPERATURES HAVE BEEN ABLE WARM AS EXPECTED WITH MANY LOCATIONS
CLIMBING ABOVE ZERO. BASED ON THE RAP HAVE MADE SOME MINOR CHANGES
TO THE HIGH TEMPERATURE TODAY.
&&
.PREVIOUS DISCUSSION...
.SHORT TERM...TODAY THROUGH SUNDAY
THE MODELS SHOW VERY GOOD AGREEMENT THROUGH THE SHORT TERM WITH
COLD NORTHWEST FLOW ALOFT DOMINATING. ABR RADAR WAS SHOWING SOME
WEAK ECHOES EARLY THIS MORNING ALONG WITH FLURRIES REMAINING IN
SOME OBS. THUS...ADDED IN SOME SCATTERED FLURRIES INTO THE
FORECAST. OTHERWISE... ARCTIC HIGH PRESSURE EARLY THIS MORNING
WILL DESCEND SLOWLY SOUTHEAST ACROSS THE REGION TODAY AND THIS
EVENING. WINDS WILL TURN FROM NORTH TO LIGHT SOUTH TO SOUTHWEST
TODAY. WITH THE MOSTLY SUNNY SKIES TODAY/LOW SUN ANGLE OVER FRESH
SNOW COVER ALONG WITH LITTLE WIND...TEMPERATURES WILL STRUGGLE TO
RISE TO TODAY. EXPECT SINGLE DIGITS FOR HIGHS WITH MAYBE SOME
LOWER TEENS SOUTHWEST. WITH LITTLE RISE IN TEMPERATURES TODAY OVER
THE NEW COVER...TEMPERATURES SHOULD FALL QUICKLY THIS EVENING WITH
LITTLE IF ANY CLOUD COVER THROUGH LATE TONIGHT. COULD SEE SOME
TEENS BELOW ZERO EAST IN THE CWA WITH LIGHT SOUTH WINDS. THE
MODELS THEN SHOW GOOD AGREEMENT WITH A SHORT WAVE TROUGH FROM THE
NORTHWEST ALONG WITH ANOTHER ARCTIC BOUNDARY MOVING ACROSS THE
REGION SATURDAY THROUGH SUNDAY. SATURDAY WILL BE ANOTHER COLD DAY
AS MID AND HIGH LEVEL CLOUDS WILL BE SPREADING IN WITH THE NEXT
SYSTEM ALONG WITH A WIND CHANGE TO THE NORTH. DEPENDING ON THE
OVERNIGHT LOWS...TEMPERATURES WILL AGAIN STRUGGLE TO REACH 10 TO
15 DEGREES ACROSS MOST OF THE CWA BY LATE AFTERNOON SATURDAY.
THE MODELS THEN SHOW SOME LIGHT QPF WITH THE SHORT WAVE TROUGH AND
CAA COMING THROUGH SATURDAY NIGHT AND SUNDAY. THIS LOOKS REASONABLE
AND PUT IN SOME POPS FOR THIS TIME PERIOD FOR LIGHT SNOW. ANOTHER
ARCTIC HIGH PRESSURE AREA WILL BUILD INTO THE REGION ON SUNDAY.
AFTER ANOTHER BITTER COLD NIGHT ON SATURDAY NIGHT...TEMPERATURES
IN THE SINGLE DIGITS BELOW ZERO WILL STRUGGLE TO REACH ZERO IN
THE EASTERN CWA WITH ZERO TO 5 ABOVE WEST IN THE CWA ON SUNDAY.
925MB TEMPERATURES WILL FALL TO -18 TO -22C BY 00Z MONDAY. WITH
THE CAA AND 925MB WINDS OF 10 TO 25 KNOTS...WE COULD ALSO HAVE
SOME ADVISORY TYPE WIND CHILLS ON SUNDAY. GENERALLY LOWERED TEMPERATURES
SOME THROUGH THE ENTIRE PERIOD.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
THE EXTENDED IS STILL CHARACTERIZED BY NORTHWEST FLOW AND BELOW
NORMAL COLD AIR. 00Z GLOBAL SPECTRAL MODEL SOLUTIONS WOULD HAVE
ONE BELIEVING THAT SEVERAL PIECES OF S/W ENERGY ARE STILL WORKING
THROUGH THE REGION BETWEEN TUESDAY AND THURSDAY...WITH CHANCES FOR
LIGHT SNOW /LOW ACCUM POTENTIAL/ OFF AND ON ACROSS THE REGION.
TIMING/PLACEMENT DIFFERENCES IN THE MODELS AND SLIGHT DIFFERENCES
IN THERMAL PROGS MADE ACCEPTING THE ALLBLEND GUIDANCE THIS MORNING
AN EASY CHOICE.
&&
.AVIATION...
12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS
WELL...THE SNOW HAS PRETTY MUCH ENDED...BUT AFTER INITIAL CLEARING
LATE LAST EVENING...A SCT-BKN MVFR DECK OF STRATUS DEVELOPED AND
HAS BEEN SLOW TO MOVE/DISSIPATE ACROSS THE FORECAST AREA. IN
FACT...SOME AREAS BENEATH THESE NEWLY DEVELOPED STRATUS CLOUDS
HAVE SEEN AN OCCASIONAL SNOW FLURRY EARLY THIS MORNING. VFR AND
MVFR SCT TO OVC STRATUS CLOUDS WILL CONTINUE TO TAKE TURNS IN
SURFACE OBS FOR THE NEXT FEW HOURS. BUT...ULTIMATELY...STRATUS
CLOUDS SHOULD SCATTER OUT BY LATE THIS MORNING LEAVING...DECENT
VFR FLYING WEATHER WITH LIGHT WINDS FOR THE REST OF FRIDAY.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&
$$
UPDATE...SD
SHORT TERM...MOHR
LONG TERM...DORN
AVIATION...DORN
WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
411 PM CST FRI DEC 20 2013
.DISCUSSION...
21Z SUBJECTIVE SURFACE ANALYSIS SHOWED A STRONG COLD FRONT IN
PLACE ALONG A LINE FROM PARIS TO DALLAS TO HAMILTON. THE
TEMPERATURE GRADIENT ALONG THIS BOUNDARY WAS QUITE IMPRESSIVE WITH
A 70 DEGREE TEMPERATURE THAT WAS OBSERVED AT GREENVILLE...A 49
DEGREE TEMPERATURE AT MCKINNEY AND A 39 DEGREE TEMPERATURE AT
DENTON. THIS FRONT WAS STILL MOVING SOUTHEAST AT 15 MPH AT THE
TIME OF THIS DISCUSSION. A 20Z AIRPLANE SOUNDING FROM DALLAS LOVE
FIELD INDICATED THAT THE FRONT WAS SHALLOW IN NATURE...WITH THE
FRONTAL INVERSION ONLY EXTENDING UP ABOUT 1500 FEET ABOVE GROUND
LEVEL. THE FRONT IS STILL EXPECTED TO STALL OUT OVER THE FAR
SOUTHEASTERN CWA THIS EVENING...IN RESPONSE TO CYCLOGENESIS
INITIATED BY THE APPROACH OF A POWERFUL UPPER LEVEL STORM SYSTEM.
THIS UPPER LEVEL STORM SYSTEM WAS OBSERVED OVER BAJA CALIFORNIA AT
20Z BASED ON WATER VAPOR SATELLITE IMAGERY. OUT AHEAD OF THIS
UPPER LEVEL STORM SYSTEM...WATER VAPOR SATELLITE IMAGERY SHOWED A
NICE CONTINUOUS BAND OF SUB-TROPICAL PACIFIC MOISTURE STREAMING
NORTHEAST OVER NORTHERN MEXICO AND THE SOUTH PLAINS. THE HIGH
TERRAIN OF NORTHERN MEXICO WILL SCOUR OUT ALL OF THE LOW TO MID-
TROPOSPHERIC MOISTURE ASSOCIATED WITH THIS SUBTROPICAL PLUME...BUT
THE MID TO UPPER LEVEL MOISTURE WILL CONTRIBUTE TO MOISTURE DEPTH
OVER THE REGION AS THE UPPER LEVEL STORM SYSTEM MOVES ACROSS THE
AREA TONIGHT INTO TOMORROW MORNING.
THROUGH TONIGHT...THE MOST TROUBLESOME FORECAST PROBLEM IN THE
SHORT TERM FORECAST IS THAT ALL FORECAST GUIDANCE IS DOING A
REMARKABLY POOR JOB RESOLVING THE STRENGTH OF THE SHALLOW COLD AIR
ASSOCIATED WITH/BEHIND THE COLD FRONT. WHILE ALL GUIDANCE IS DOING
A POOR JOB RESOLVING SURFACE TEMPERATURES NORTH OF THE COLD
FRONT...THE RAP IN PARTICULAR IS DIFFICULT TO PROCESS BECAUSE IT
CONTINUES TO INITIALIZE THE COLD AIR...BUT PERSISTENTLY BRINGS
SURFACE TEMPERATURES UP 5-7 DEGREES AT FORECAST HOUR 1 DESPITE
PERSISTENT COLD AIR ADVECTION AND CLOUD COVER. THIS WOULD BE MORE
OR LESS A NUISANCE IF THE TEMPERATURES HAD NO POTENTIAL TO HAVE AN
IMPACT ON PRECIPITATION TYPE IN THIS FORECAST. FOR INSTANCE...AT
BOWIE...THE 21Z OBSERVATION HAD A TEMPERATURE OF 32 DEG F. THE RAP
INITIALIZES THIS AT 34 DEGREES...WHICH IS NOT TOO FAR OFF...BUT
THEN GOES AHEAD TO FORECAST A TEMPERATURE OF 40 DEGREES BY 22Z.
WITH WIDESPREAD RAINFALL DEVELOPING OVER THE REGION RIGHT
NOW...AND EXPECTED TO PERSIST THIS EVENING INTO THE OVERNIGHT
HOURS...THIS ERROR IN RESOLVING NEAR SURFACE TEMPERATURES IS QUITE
PROBLEMATIC. THEREFORE...AT THIS TIME...WITH NO GUIDANCE AVAILABLE
ACTUALLY RESOLVING THE STRENGTH OF THIS COLD AIR...THE
PRECIPITATION TYPE FORECAST FOR TONIGHT WAS COMPLETED USING
OBSERVATIONAL TRENDS...RECENT FORECAST EVENTS AND INTUITION.
AT THIS TIME EXPECT THAT TEMPERATURES ALONG AND NORTHWEST OF A
GAINESVILLE TO GRAHAM LINE ARE MOST LIKELY TO FALL TO 32 DEGREES
THIS EVENING...LIKELY HOLDING STEADY THROUGH MUCH OF THE OVERNIGHT
HOURS. AS A RESULT...EVEN IF WE SEE RAIN AT 31 TO 32 DEGREES FOR
SEVERAL HOURS...THE CURRENT THINKING IS THAT WE WILL NOT SEE ANY
ICE ACCUMULATION...EXCEPT PERHAPS ON TREE TOPS OR THE TOPS OF
EXPOSED METAL SURFACES. THE REASONS FOR THIS ARE AS FOLLOWS:
1. BEFORE THE FRONT...WE HAVE EXPERIENCED A FEW DAYS OF ABOVE
NORMAL TEMPERATURES. GROUND/ROAD TEMPERATURES ARE WELL ABOVE
FREEZING WHICH WILL NOT ALLOW FOR ICE ACCUMULATION.
2. THE DEPTH OF THE ELEVATED WARM LAYER IS ALMOST 8 TIMES AS DEEP
AS THE DEPTH OF THE COLD/SUB-FREEZING LAYER. RAIN FALLING IN THIS
ENVIRONMENT WILL LIKELY HAVE A TEMPERATURE ABOVE FREEZING WHEN IT
REACHES THE SURFACE. THAT IS THE TEMPERATURE OF THE FALLING RAIN
DROPS ARE LIKELY TO BE ABOVE FREEZING...THIS IS ALSO NOT CONDUCIVE
TO ICE ACCUMULATION.
3. ALL GUIDANCE INDICATES PERSISTENT WARM AIR ADVECTION THROUGH
12Z SATURDAY ABOVE THE COLD FRONTAL INVERSION. THE WARM LAYER IS
VERY LIKELY TO MAINTAIN ITS DEPTH AND STRENGTH...WHILE RELATIVELY
WARM RAIN DROPS MAY ACTUALLY SHRINK THE DEPTH OF THE SHALLOW COLD
AIR OVERNIGHT.
AS A RESULT...WILL NOT BE HIGHLIGHTING FREEZING RAIN IN THE
FORECAST AT THIS TIME...DESPITE THE SURFACE OBSERVATION AT BOWIE
AT 32 DEGREES SEEMINGLY SHOWING AN ICE STORM ON OUR DOORSTEP. IT
LOOKS LIKE THE DEPTH OF THE COLD AIR WILL ONLY SUPPORT ICE
ACCUMULATION FARTHER NORTH...WELL INTO OKLAHOMA BASED ON
OBSERVATIONAL ANALYSIS AND DFW AREA AIRCRAFT SOUNDINGS.
DESPITE ALL THAT HAS BEEN DISCUSSED ABOUT THE SHALLOW COLD AIR
PROBLEM...THERE WERE ACTUALLY NO SIGNIFICANT CHANGES MADE TO THE
PREVIOUS FORECAST WHICH REMAINS LARGELY ON TRACK. THE BAJA UPPER
LEVEL LOW IS STILL EXPECTED TO MOVE OVER THE SOUTH PLAINS TOMORROW
MORNING...SPREADING STRONG LARGE SCALE FORCING FOR ASCENT OVER THE
REGION TONIGHT THROUGH TOMORROW MORNING. NEARLY ALL GUIDANCE
INDICATES THAT THE UPPER LOW WILL BECOME INCREASINGLY NEGATIVELY
TILTED AS IT MOVES OUT OVER TEXAS...DEEPENING AS IT MOVES OVER THE
CWA. THE STRONGEST FORCING FOR ASCENT LOOKS TO MOVE OVER THE CWA
IN THE 09 TO 15Z TIME FRAME...WHICH SHOULD ALSO REPRESENT OUR
WINDOW FOR THE BEST COVERAGE AND HEAVIEST PRECIPITATION RATES
DURING THIS EVENT.
FOR THIS EVENING...THE COLD FRONT PUSHING SOUTH THROUGH MOST OF
THE CWA WILL SIMPLY HELP TO STEEPEN LOW-LEVEL ISENTROPIC SURFACES
AS CYCLOGENESIS RAMPS UP NEAR DEL RIO RESULTING IN AN INCREASE OF
THE STRENGTH OF THE LOW TO MID-LEVEL WIND FIELD. THIS SHOULD
RESULT IN A SPREAD OF THE COVERAGE OF ONGOING RAIN SHOWER
ACTIVITY FROM WEST TO EAST ACROSS THE CWA. AS THE UPPER LEVEL LOW
APPROACHES...ASSUMING IT BECOMES MORE NEGATIVELY TILTED AS
ADVERTISED...WE SHOULD SEE AN ENHANCEMENT OF MID-LEVEL LAPSE RATES
WITH SOME UPPER-LEVEL COLD AIR ADVECTION OVER THE PERSISTENT LOW-
LEVEL WARM AIR ADVECTION REGIME. THIS WILL RESULT IN AN INCREASED
CHANCE OF ISOLATED THUNDERSTORMS EMBEDDED IN THE RAIN SHOWER
ACTIVITY FROM SUNSET TO MIDNIGHT. ALL OF THIS ACTIVITY SHOULD
REMAIN ELEVATED IN NATURE...AND POSES VERY LITTLE SEVERE WEATHER
THREAT AS A RESULT. RAINFALL RATES WILL BE ENHANCED...AND
THEREFORE SOME LOCALIZED HEAVY RAINFALL IS POSSIBLE.
AFTER MIDNIGHT...AS MENTIONED ABOVE...THE BEST LARGE SCALE FORCING
FOR ASCENT IS EXPECTED TO BUILD ACROSS THE CWA FROM WEST TO EAST
DURING THIS TIME RESULTING IN THE STRONGEST AND MOST WIDESPREAD
CONVECTION AND PRECIPITATION FOR THE REGION. BASED ON THE POSITION
OF THE COLD FRONT AT THAT TIME...WE DO HAVE A WINDOW FOR SURFACE
BASED SEVERE STORMS BASED ON CONVECTIVE PARAMETERS ADVERTISED IN
THE MAJORITY OF GUIDANCE. LOCATIONS ALONG AND SOUTHEAST OF
WHEREVER THE COLD FRONT STALLS OUT WOULD BE THE ONLY LOCATIONS
WHERE SURFACE BASED SEVERE STORMS WOULD BE POSSIBLE. FORECAST
CONVECTIVE PARAMETERS INDICATED SURFACE BASED CAPE VALUES OF
AROUND 1000 J/KG WITH 0-3 KM CAPE VALUES OF AROUND 100 J/KG AND
DEEP LAYER SHEAR VALUES IN EXCESS OF 50 KTS.
THESE VALUES ARE SUPPORTIVE OF A LOW-TOPPED SUPER CELLULAR STORM
MODE...WHICH COULD RESULT IN LARGE HAIL...DAMAGING WIND OR
ISOLATED TORNADOES. THIS THREAT IS MODERATED BY STRONG FORCING
WHICH MAY MAKE AN ISOLATED STORM MODE DIFFICULT TO REALIZE...AND
STRONG CLOUD LEVEL WINDS THAT WILL LIKELY TAKE STORMS THAT DEVELOP
ALONG THE FRONT...OVER/NORTH OF THE FRONT SHORTLY AFTER
INITIATION. REGARDLESS...WILL BE WATCHING FOR WHERE THE FRONT
STALLS OUT TONIGHT AS LOCATIONS NEAR AND TO THE SOUTHEAST OF THE
BOUNDARY ARE THE MOST LIKELY TO SEE SEVERE WEATHER. FURTHER
NORTHWEST...STRONG STORMS REMAIN POSSIBLE...HOWEVER EVEN ELEVATED
SUPERCELLS ARE ONLY GOING TO PROVIDE A THREAT FOR MARGINALLY
SEVERE HAIL...SO THE OVERALL SEVERE WEATHER THREAT NORTHWEST OF
THE FRONT DIMINISHES GREATLY.
FOR ANYWHERE ACROSS NORTH TEXAS...LOCALLY HEAVY RAINFALL IS
POSSIBLE WHICH MAY RESULT IN SOME LOCALIZED FLASH FLOODING ISSUES
OVER THE NEXT 24 HRS. WITH THE SUB-TROPICAL PACIFIC MOISTURE FEED
IN PLACE...AND LOW-LEVEL WARM MOIST ADVECTION EXPECTED TO RAMP UP
IN INTENSITY OVER THE SHALLOW COLD FRONT...NEARLY ALL GUIDANCE
INDICATES THAT PWAT VALUES WILL BE UP AROUND 1.5 INCHES ACROSS
NORTH AND CENTRAL TEXAS AS THE UPPER LOW SPREADS STRONG FORCING
OVER THE REGION. 1.5 INCH PRECIPITABLE WATER VALUES RANK AS PLUS 3
STANDARD DEVIATION FOR NORTH TEXAS AT THIS TIME OF YEAR. THIS
EXCEPTIONALLY DEEP MOISTURE COMBINED WITH FAVORABLE DYNAMICS FOR
WIDESPREAD PRECIPITATION SUPPORT A LOCALIZED HEAVY RAINFALL THREAT
WITH AN ATTENDANT LOCALIZED FLOODING THREAT TONIGHT INTO TOMORROW
MORNING. DID NOT ISSUE A FLASH FLOOD WATCH AT THIS TIME BECAUSE
OUR PRIMARY WINDOW FOR HEAVY RAINFALL IS ONLY EXPECTED TO BE ON
THE ORDER OF 6 HOURS OR SO. IF STRONG FORCING WAS EXPECTED TO BE
IN PLACE FOR A LONGER PERIOD OF TIME...THE THREAT OF WIDESPREAD
FLOODING WOULD BE MUCH GREATER AND A WATCH WOULD HAVE BEEN ISSUED.
AT THIS TIME THE THREAT OF FLOODING IS EXPECTED TO REMAIN
LOCALIZED AND MAINLY CONFINED TO LOW LYING/COMMONLY FLOODED AREAS.
HEAVY PRECIPITATION IS EXPECTED TO COME TO AN END FROM SOUTHWEST
TO NORTHEAST SATURDAY AFTERNOON AS A STRONG MID-LEVEL DRY SLOT
PUNCHES OVER THE REGION. LIGHT RAIN MAY PERSIST ACROSS THE AREA
SATURDAY AFTERNOON...BUT EVEN THIS WILL BE SCOURED OUT BY SUNSET.
REMAINDER OF THE FORECAST...NO SIGNIFICANT CHANGES WERE MADE TO
THE PREVIOUS FORECAST AS MOST OF THE ACTIVITY IN THE FORECAST IS
IN THE FIRST 24 HOURS. HIGHLIGHTS OF THE REMAINDER OF THE FORECAST
INCLUDE:
1. ADDED A MENTION OF SPRINKLES/LIGHT RAIN TO THE FORECAST ALONG
THE COLD FRONT THAT IS EXPECTED TO PUSH SOUTH THROUGH THE CWA ON
SUNDAY MORNING. WILL HAVE TO WATCH TEMPERATURES CLOSELY SUNDAY
MORNING AS THIS FRONT ROLLS THROUGH...HOWEVER ALL GUIDANCE
INDICATES TEMPERATURES JUST ABOVE FREEZING WITH THIS VERY LIGHT
PRECIPITATION.
2. WE SHOULD BE DRY EARLY NEXT WEEK...LEADING UP TO CHRISTMAS DAY.
TEMPERATURES WILL SLOWLY WARM THROUGH CHRISTMAS...ALTHOUGH HIGHS
ARE EXPECTED TO REMAIN BELOW NORMAL THROUGH THE WEEK AHEAD.
3. AN UPPER LEVEL STORM SYSTEM MAY RESULT IN SCATTERED RAIN
SHOWERS ACROSS THE REGION ON CHRISTMAS DAY. AT THIS TIME
TEMPERATURES ARE EXPECTED TO BE WELL ABOVE FREEZING...SO NO
SIGNIFICANT IMPACTS ARE EXPECTED AT THIS TIME.
CAVANAUGH
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 37 47 36 48 29 / 100 100 10 10 5
WACO, TX 42 62 37 50 30 / 80 100 10 10 5
PARIS, TX 41 45 36 47 26 / 100 100 10 10 10
DENTON, TX 37 44 34 47 26 / 100 100 10 10 5
MCKINNEY, TX 38 44 35 46 25 / 100 100 10 10 5
DALLAS, TX 38 46 38 48 30 / 100 100 10 10 5
TERRELL, TX 41 47 37 47 28 / 100 100 10 10 5
CORSICANA, TX 46 54 39 48 30 / 80 100 10 10 5
TEMPLE, TX 46 63 39 52 31 / 80 100 10 10 5
MINERAL WELLS, TX 36 49 34 48 24 / 100 90 10 10 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
/
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1054 PM EST SAT DEC 21 2013
.SYNOPSIS...
A VERY MILD AND MOIST AIRMASS WILL REMAIN IN PLACE THROUGH THE
WEEKEND AHEAD OF AN APPROACHING COLD FRONT. SIGNIFICANT RAINFALL
IS POSSIBLE IN MANY LOCATIONS AHEAD OF THE FRONT SUNDAY INTO PARTS
OF MONDAY. THE FRONT WILL MOVE THROUGH THE AREA ON MONDAY...AND
WITH IT WILL COME AN ABRUPT END TO OUR VERY MILD WEATHER. COLDER
HIGH PRESSURE BUILDS OVER THE REGION BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 1040 PM EST SATURDAY...
A SLOW MOVING COLD FRONT WILL CONTINUE INCHING EASTWARD THROUGH THE
MID-MISSISSIPPI AND LOWER OHIO RIVER VALLEYS. AHEAD OF THE
FRONT...S-SW LOW LEVEL FLOW WILL INCREASE TO 50 TO 60 KTS AT 850 MB
AND ADVECT PLENTY OF GULF OF MEXICO MOISTURE INTO THE REGION. THIS
MOISTURE WILL BE REALIZED IN ABUNDANT CLOUD COVER...VERY HIGH
SURFACE DEW POINTS FOR LATE DECEMBER. HAVE RAISED PROBABILITY OF
PRECIPITATION ALONG THE CREST OF THE BLUE RIDGE FROM NEAR FLOYD
SOUTHWEST INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA.
ANOTHER REGION TO WATCH FOR PRECIPITATION IS SOUTHEAST WEST
VIRGINIA. THIS AREA WILL BE CLOSEST TO THE ACTUALLY FRONT...AND
WEAK DISTURBANCES ALONG THE FRONT WILL HELP TO BRING PERIODIC
WIDELY SCATTERED COVERAGE TO THIS PART OF THE FORECAST AREA
OVERNIGHT. MAIN AREA OF PRECIPITATION CLOSER TO THE FRONT IS NOT
EXPECTED TO ARRIVE IN THE WESTERN COUNTY WARNING AREA UNTIL AFTER
12Z/7AM. THIS TIMING IS SUPPORT BY THE LATEST HRRR AND RAP MODELS
AS WELL AS THE 18Z LOCAL WRF.
THE HIGH DEW POINTS WILL ALLOW FOR EQUALLY MILD OVERNIGHT LOW
TEMPERATURES. WE ARE EXPECTING NEW RECORD HIGH MINIMUM TEMPERATURES
EVERYWHERE TONIGHT. LOWS WILL RANGE FROM THE UPPER 50S TO NEAR 60
IN THE MOUNTAINS WITH LOWER 60S ACROSS THE PIEDMONT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
AS OF 350 PM EST SATURDAY...
SUNDAY BEGINS WITH MILD TEMPS AND HEALTHY SOUTH TO SOUTHWEST FLOW
UP ALONG BLUE RIDGE WITH VISIBILITIES SOCKED IN ALONG BLUE
RIDGE...LIGHT SHOWERS...AND WITH HEAVIER BAND OF RAIN SHOWERS JUST
ENTERING FAR SOUTHWEST VA AND NW NC AROUND DAYBREAK MODELS HAVE
DEFINITELY SLOWED THIS DOWN. SEEING EXTREMELY LIMITED INSTABILITY
FOR THUNDER...BUT WENT AHEAD ADDED SLIGHT CHC OF THUNDER BY NOON
FOR MUCH OF SW VA AND NW NC. SHALLOW LINE OF CONVECTION MAY HAVE
VERY GUSTY WINDS WITH IT AS IT ENTERS FAR WESTERN PORTION OF FCST
AREA...BUT MOST MODELS HAVE THIS WEAKENING QUICKLY AS IT ENTERS
DURING THE MID MORNING HOURS. CANT RULE OUT SOME DAMAGING WINDS
WEST OF I-81 AND SOUTH OF 460...MAYBE INTO NW NC. GENERALLY SW
WINDS WILL BE GUSTY AHEAD OF THIS...AND MAY REACH ADVISORY
CRITERIA AT VERY HIGHEST RIDGES...BUT SHOULD BE ISOLATED
ENOUGH...AND NOT HIGH ENOUGH POTENTIAL WITH CONVECTIVE LINE OF
SHOWERS...TO ISSUE A WIND ADVISORY AT THIS TIME.
BY AFTERNOON...PARTS OF THIS LINE OF SHALLOW CONVECTION SHOULD
SNEAK INTO PIEDMONT...BUT THIS MAY NOT OCCUR UNTIL VERY LATE IN
AFTERNOON ACCORDING TO LATEST TRENDS. STILL UPSLOPE FLOW FROM
SOUTH ALONG BLUE RIDGE SHOULD BE ENHANCING PRECIP AMOUNTS THERE
REGARDLESS OF TIMING OF THIS HEAVIER BAND OF SHOWERS...POSSIBLE
ISOLATED THUNDER. NAM STILL IS SLOWEST AND LARGELY DUE TO STRONGLY
INFLUENCE OF THIS WAVE RIDING UP FROM THE SOUTHWEST...AND SPREADS
MORE PRECIP BACK TOWARD THE WEST AGAIN SUNDAY NIGHT AND MONDAY.
SOME HINTS OF THIS IN GFS BUT IT STILL REMAINS MOST PROGRESSIVE.
HEAVIEST RAINFALL FROM NAM AND SOME HIGH RES MODELS SUGGESTED
ALONG BLUE RIDGE...WHILE GFS AND ECMWF MORE OUT INTO PIEDMONT
THROUGH SUNDAY NIGHT AND MONDAY. GENERALLY GOING CLOSER TO
GFS/ECMWF IDEA...AND NOT QUITE AS WET AS GFS...BUT DID ENHANCE THE
RAINFALL ALONG BLUE RIDGE MORE SO THAN WHAT THESE MODELS HAVE.
THUS HAVE INCREASED OVERALL STORM QPF SIGNIFICANTLY...WITH 2.5 TO
3 INCHES FROM BLUE RIDGE EAST. PLEASE READ THE HYDROLOGY SECTION
BELOW FOR MORE DISCUSSION ON THE RAINFALL AND FLOODING
POTENTIAL...BUT FOR NOW HAVE NOT GONE WITH ANY FLOOD
HEADLINES...BUT WILL HIGHLIGHT IN THE HWO.
AS FAR AS TEMPERATURES...STILL LOOKING AT A RECORD BREAKING MILD
AFTERNOON, DESPITE EXTENSIVE CLOUD COVER AND RAIN ACROSS THE
WEST...BUT WITH THE PIEDMONT HOLDING OFF ON RAIN UNTIL
LATE...LIKELY TO SEE MID 70S. JUST ABOUT ALL LOCATIONS SHOULD
TIE OR BREAK A RECORD MAX TEMP FOR THE DATE. SEE CLIMATE SECTION
BELOW FOR RECORDS.
ON MONDAY THE COLDER AIR BEHIND THE FRONT BEGINS TO FILTER
IN...BUT NOT AS FAST AS PREVIOUSLY THOUGHT...AS EVEN THE MORE
PROGRESSIVE GFS HAS SLOWED THINGS DOWN WITH THIS WAVE. COLD AIR
MAY BEGIN TO RUSH IN LATE IN THE DAY IN THE WEST...BUT WILL
PROBABLY NOT ARRIVE IN THE EAST UNTIL MONDAY EVENING. AGAIN...SOME
MODEL DIFFERENCES STILL IN TERMS OF HOW FAR WEST THIS WAVE WILL
SPREAD OR DEVELOP MORE PRECIP...AND HAVE NOT DROPPED POPS TOO LOW
ACROSS THE FAR WEST FOR THIS REASON...BUT THERE COULD BE A BREAK
MOST OF MONDAY FOR MUCH OF THE WEST WHILE SHOWERS STILL PLAGUE THE
BLUE RIDGE AND THE PIEDMONT MOST OF THE DAY BEFORE FINALLY
PUSHING EAST AFTER THE WAVE GOES BY LATE IN THE DAY.
WITH WESTERLY FLOW...SOME UPSLOPE SHOWERS COULD LINGER IN TYPICAL
UPSLOPE FAVORED AREAS OF THE WEST...BUT CHANCES INCREASE FOR
MEASURABLE PRECIP BY LATE MONDAY NIGHT OR EARLY TUES MORNING WITH
STRONG UPPER TROUGH AND SHORT WAVE DIGGING QUICKLY ACROSS THE
AREA. STRONG COLD ADVECTION BY THIS TIME...AND WHILE LOW LEVEL
WINDS MORE WESTERLY...NOT IDEAL FOR BEST UPSLOPE SNOWS...THE
ADVECTION OVER VERY MOIST GROUND JUST UPSTREAM IS STILL A CONCERN.
STILL LEANING MORE TOWARD THE MODELS THAT PRODUCE SOME LIGHT
UPSLOPE ACCUMULATIONS MONDAY NIGHT INTO EARLY TUES MORNING. RIGHT
NOW THINKING A VERY LIGHT ACCUM IN NW NC MTNS...WITH AN INCH OR
TWO IN WESTERN GREENBRIER WV. NAM STILL STINGY ON THIS...BUT
THINKING GFS HAS BEST HANDLE...AND COULD EVEN BE MORE.
THIS WAVE MOVES QUICKLY THROUGH AND SHOULD DRY OUT QUICKLY DURING
THE DAY TUES..WITH CONTINUED STRONG COLD ADVECTION...DOESN`T LOOK
LIKE WIND ADV CRITERIA WIND SPEEDS AT THE MOMENT...AND MUCH COLDER
TEMPS WITH MANY AREAS OF THE WEST REMAINING BELOW FREEZING FOR THE
DAY. WENT WITH COLDER ECMWF MOS-BASED GUIDANCE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 320 PM EST SATURDAY...
STRONG DRY ARCTIC HIGH PRESSURE WILL LEAD TO SOME VERY COLD MORNINGS
NEXT WEEK...POSSIBLY SINGLE DIGITS IN THE DEEPEST COLDEST VALLEYS
WEDNESDAY MORNING. OTHERWISE A RATHER BENIGN PATTERN WITH A DRY COLD
FRONT CROSSING THURSDAY NIGHT. ANOTHER BOUNDARY DROPPING THROUGH THE
UPPER MIDWEST LATE NEXT WEEKEND WILL MEAN SW SURFACE
FLOW...POTENTIALLY PUSHING H85 TEMPS TO NEAR +5C. A COLDER PATTERN
COULD ARRIVE PAST NEXT WEEKEND AS THE POLAR VORTEX DIVES SOUTH
THANKS TO AN UPPER RIDGE POTENTIALLY LINKING FROM GREENLAND TO
ALASKA.
&&
.AVIATION /04Z SUNDAY THROUGH THURSDAY/...
AS OF 715 PM EST SATURDAY...
IFR STRATUS COVERED MUCH OF THE SOUTHERN BLUE RIDGE THIS EVENING.
MODERATE CONFIDENCE THAT CEILINGS WILL REMAIN ABOVE IFR AT
KLYH/KDAN/KROA/KBCB THROUGH MIDNIGHT.
OVERNIGHT...MOISTURE TRANSPORT INCREASES ACROSS THE AREA ON
50 TO 60 KT 850 MB WINDS. ANTICIPATE A TREND TOWARD MORE MVFR CIGS
ACROSS THE REGION WITH LOCALIZED IFR CIGS AND MVFR VSBYS. LIGHT
RAIN SHOWERS WILL BECOME MORE NUMEROUS...ESPECIALLY ALONG THE
CREST OF THE BLUE RIDGE AND ALSO NEAR A KLWB-KBLF LINE. WIND GUSTS
UP TO 30 KNOTS ARE POSSIBLE...ESPECIALLY FROM 1AM THROUGH 8AM.
ON SUNDAY MORNING THE SURFACE COLD FRONT MOVES INTO THE
MOUNTAINS...AND MOISTURE WILL CONTINUE TO STREAM ACROSS THE
REGION. A REINFORCING WAVE WILL MOVE NORTH ALONG THE FRONT AND
DELAY THE FRONTAL PASSAGE EAST OF THE BLUE RIDGE UNTIL MONDAY.
EXPECT A SHARP WIND SHIFT AS A COLD FRONT COMES THROUGH...THEN
GUSTY NORTHWEST WINDS ON MONDAY. UPSLOPE SNOW SHOWERS ARE EXPECTED
ACROSS SE WV MONDAY NIGHT THROUGH TUESDAY. LOCALIZED MVFR
CONDITIONS ARE EXPECTED.
VFR CEILINGS AND VISIBILITIES RETURN ON WEDNESDAY AND THURSDAY AS HIGH
PRESSURE AND DRIER AIR COME INTO THE REGION.
&&
.HYDROLOGY...
AS OF 335 PM EST SATURDAY...
MODEL TRENDS TOWARD HIGHER PRECIP AMOUNTS SUNDAY NIGHT AND MONDAY...AND
THIS NOT SURPRISING GIVEN SECOND WAVE RIDING UP ALONG FRONT
SLOWING IT DOWN..WITH STRONG FETCH OF MOISTURE ADVECTION FROM
GULF. FORECAST PRECIPITABLE WATER VALUES OF 1.5 TO 1.7 INCHES
WOULD BE RECORD OR NEAR RECORD VALUES FOR DECEMBER. WHILE SOME
HIGH RESOLUTION MODELS ARE LIKELY OVERDOING THE MAXIMUM PRECIP
OUTPUT...SOME SIGNS THAT TWO AREAS OF CONCERN ARE ALONG THE BLUE
RIDGE SUNDAY THROUGH EARLY MONDAY...AND ALSO OUT IN THE PIEDMONT
MAINLY SUNDAY NIGHT AND MONDAY. CURRENT FORECAST AMOUNTS ARE
BETWEEN 2 AND JUST OVER 3 INCHES...AND THIS MAY BE ENOUGH TO CAUSE
NOT ONLY LOCALIZED FLOODING OF SMALL STREAMS AND CREEKS...BUT
COULD BRING THE DAN RIVER UP TO ACTION OR MINOR FLOOD STAGE BY
TUESDAY FROM UPSTREAM AND LOCAL RUNOFF. MAY ALSO HAVE TO WATCH THE
HEADWATERS OF THE NEW RIVER IN NW NC FOR SUNDAY NIGHT...AS WELL
AS ROANOKE RIVER FOR MON/TUES TIME FRAME. IF HIGHER RESOLUTION
MODELS ARE CORRECT...THERE COULD BE MUCH MORE SIGNIFICANT FLOODING
PROBLEMS...BOTH FLASH FLOOD AND RIVER FLOOD. NOT CONFIDENT ENOUGH
YET TO GO WITH A WATCH OF ANY KIND YET.
&&
.CLIMATE...
RECORDS FOR THE WARMEST LOW TEMPERATURE AT EACH CLIMATE SITE FOR
THE MONTH OF DECEMBER ARE AT RISK OF BEING TIED OR BROKEN...ESPECIALLY
ACROSS THE PIEDMONT.
HIGHEST LOW TEMPERATURES FOR THE MONTH OF DECEMBER...
BLACKSBURG 55/DEC 23 1990
ROANOKE 60/DEC 14 1927
LYNCHBURG 62/DEC 16 1971
DANVILLE 60/DEC 6 2011
BLUEFIELD 58/DEC 22 1990
LEWISBURG 58/DEC 28 1982
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY UNTIL NOON EST SUNDAY FOR VAZ007-009-015-018>020-
022>024-034-035.
NC...WIND ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018.
WV...WIND ADVISORY UNTIL NOON EST SUNDAY FOR WVZ043>045.
&&
$$
SYNOPSIS...KK/SK
NEAR TERM...AMS/DS
SHORT TERM...SK
LONG TERM...KM
AVIATION...AMS/DS
HYDROLOGY...SK
CLIMATE...CF/DS/SK
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
948 PM CST SAT DEC 21 2013
.UPDATE...
IF NOT FOR THE FAIRLY WIDESPREAD...THOUGH LIGHT...FREEZING DRIZZLE
WOULD HAVE DELAYED START OF WINTER STORM WARNING FOR BOTH THE
SOUTHERN AND NORTHERN SEGMENTS AS SNOW HAS BEEN SLOW TO REACH THE
AREA. WARM CONVEYOR BELT MOISTURE WELL-EVIDENT ON WATER
VAPOR...BUT 00Z REGIONAL RAOBS SUPPORTING RAP SOUNDINGS WITH THE
NEARLY 150 MB DEEP DRY LAYER BETWEEN THE JUST-NOW MOISTENING
DENDRITE GROWTH ZONE AND THE SATURATED LAYER BELOW 850 MB.
00Z NAM HAS 1...DELAYED THE START OF THE ACCUMULATING SNOW UNTIL
AFTER 12 MIDNIGHT. 2...NO LONGER SHOWING THE CONVECTIVE SIGNAL IN
THE LAYER WETZEL INGREDIENTS PLOTS THAT EARLIER RUNS HAD...WHICH
REDUCES CHANCES OF SEEING THUNDERSNOW IN THE CWA. 3...APPEARS TO
BE BRINGING THE HIGHER QPF AMOUNTS IN BETWEEN 12Z AND 15Z WHICH
THE NEW GFS ALSO SEEMS TO SUPPORT.
SIGNS ARE BEGINNING TO POINT TO THE HEAVIEST SNOW FALLING IN THE
09Z TO 15Z TIME FRAME...WITH THE FAR NE MAYBE NOT SEEING THE
BEGINNING OF HEAVY SNOW UNTIL CLOSE TO 12Z.
WILL NOT ALTER THE GOING FORECAST MUCH MORE THAN A FEW MORE TWEAKS
TO EARLIER ADJUSTMENTS ON THE TIMING OF STEADY SNOW. GFS AND NAM
FORECAST QPF FROM 00Z SUN TO 00Z MON ALSO REDUCED FROM GOING
FORECAST BUT STILL IN THE 0.45 TO 0.50 RANGE ON AVERAGE. EARLIER
REDUCTION OF SNOW AMOUNTS TO 5 TO 8 INCHES VERSUS 6 TO 9 LOOKS
LIKE A GOOD MOVE.
&&
.AVIATION/06Z TAFS/...
IFR/LIFR CONDITIONS WILL CONTINUE THROUGH MOST OF THE FORECAST.
HAVE TRIMMED BACK START OF HEAVY SNOW AT ALL TAF SITES. LOOKS AS
IF THE BETTER ACCUMULATIONS WILL NOT START UNTIL 08-09Z AND WILL
CONTINUE A BIT LATER UNTIL AROUND 15Z TO 16Z. WILL ADJUST PRIOR TO
ISSUANCE BASED ON TRENDS. KENW STILL LOOKS TO BE IN A STORM TOTAL
SNOW MINIMUM FOR THE TAF SITES WITH ABOUT 4 TO 5 INCHES BY 00Z
MONDAY. NORTHEAST WINDS ARE INCREASING AND WILL BE GUSTY OVERNIGHT
THEN TURN NORTH AND SLOWLY LOWER THROUGH THE DAY SUNDAY AS THE LOW
PULLS AWAY.
&&
.MARINE...
NORTHEAST WINDS FREQUENTLY GUSTING BETWEEN 22 AND 25 KNOTS AND ARE
EXPECTED TO GUST UP TO 30 KNOTS AT TIMES OVERNIGHT AND TURN NORTH.
WINDS WILL FALL BELOW CRITERIA IN THE AFTERNOON SUNDAY...BUT
GIVEN THE PERSISTENT NORTH FETCH IT WILL TAKE AWHILE FOR WAVES TO
SUBSIDE. CURRENT END TIME LOOKS REASONABLE.
&&
.PREV DISCUSSION... /ISSUED 246 PM CST SAT DEC 21 2013/
TONIGHT AND SUNDAY - CONFIDENCE...MEDIUM
WINTER STORM STILL ON SCHEDULE TO IMPACT THE AREA TONIGHT INTO SUNDAY.
12Z NAM THE ONLY WARM MODEL SUGGESTING A MIX LINGERS THE LONGEST IN
THE SOUTHEAST. THE NAM ALSO SUGGESTS POTENTIAL FOR CONVECTION PER
WETZEL INGREDIENT PLOTS. THIS SHOWS UP AT 700 THROUGH 500
MILLIBARS...AND RIGHT ALONG LEADING EDGE OF MID LEVEL DRY SLOT
WRAPPING INTO THE FAR SOUTHEAST... WHERE THERMAL PROFILE IS ALREADY
QUESTIONABLE. SHOULD NAM SCENARIO PAN OUT ANY CONVECTION WOULD LEAD
TO LOCALLY HIGHER SNOW AMOUNTS WHERE WE CURRENTLY HAVE A RELATIVE
MIN DUE TO THE MIX CONSIDERATIONS AND HIGHER QPF PROGGD TO THE
NORTHWEST. FOR THE AFOREMENTIONED REASONS WILL HANG ONTO WARNING FOR
RACINE/KENOSHA COUNTIES EVEN THOUGH CURRENT FORECAST AMOUNTS NOT
SUPPORTIVE. WATER VAPOR LOOP SHOWS IMPRESSIVE CIRCULATION IN TX
PANHANDLE BEGINNING TO LIFT NORTHEAST. NO SHORTAGE OF MOISTURE WITH
THIS SYSTEM. NO ANALYSIS OF ALL THE VARIOUS MODEL SOUNDINGS SHOW
ONLY THE NAM WITH A WARM LAYER IN THE KENOSHA AREA. WILL STILL
MENTION A MIX THIS EVENING BUT KEEP IT CONFINED TO THE EXTREME
SOUTHEAST. BASED ON GEM/ECMWF AND GFS SURFACE/850 LOW TRACKS WILL
ESSENTIALLY RETAIN THE GOING AXIS OF HEAVY SNOWFALL. QPF NUMBERS
HAVE COME DOWN A BIT AND THIS MAY BE DUE TO THE CONVECTION PROGGD TO
ERUPT TO OUR SOUTHEAST...WHICH VERY WELL MAY BE HAVING A SAY IN THE
MOISTURE FLUX INTO SRN WI. BUT AT THIS TIME ONLY A SUBTLE TWEEK
DOWNWARD IN QPF NUMBERS. THE NAM QPF LOOKS A BIT HEAVY HANDED SO
TRENDED TOWARDS AN AMALGAM OF GFS/ECMWF/HPC/CONSALL. THIS KEEPS
EVENT NUMBERS IN THE 4-8 RANGE...LOWEST AMOUNTS BEING IN THE FAR
SOUTHEAST. EXPECTING THIS SNOWFALL TO BE OF THE WET AND HEAVY
VARIETY ESPECIALLY IN THE EASTERN CWA. RATIOS EXPECTED TO START OFF
ON THE LOW SIDE AND THEN EVENTUALLY INCREASE AS COLDER AIR WRAPS
INTO THE SYSTEM. SO IN THE 12-18Z RANGE EXPECT RATIOS TO INCREASE
FROM NORTHWEST TO SOUTHEAST.
SUNDAY NIGHT INTO MONDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM.
AS THE WINTER STORM LOW PRESSURE SYSTEM MOVES OFF TO THE EAST...AN
INVERTED TROF WILL DEVELOP AND HANG BACK ACROSS CENTRAL WISCONSIN.
THIS IS IN RESPONSE TO A STRONG MID LEVEL TROF/SHORT WAVE THAT
WILL MOVE IN DURING THE PERIOD...EXITING TO THE EAST MONDAY
EVENING. THIS DEEP CONVERGENCE ZONE SHOULD BE GOOD FOR SOME LIGHT
SNOW DURING THIS PERIOD. COULD SEE A FEW MORE INCHES OF
SNOW...ESPECIALLY GIVEN HOW COLD IT WILL BE AND THE HIGH RATIOS
EXPECTED. THE FOCUS SHOULD BE MAINLY OVER THE NORTHEAST HALF OF
THE FORECAST AREA...WITH DIMINISHING CONCERN SOUTHWEST. THIS WILL
BE A COLD PERIOD. HIGHS ONLY IN THE TEENS TO LOW 20S ON
MONDAY...DROPPING INTO THE SINGLE DIGITS BELOW ZERO MONDAY NIGHT.
THAT IS A BIT TRICKY...THOUGH...AS ANY CLOUDS THAT DECIDE TO HANG
ON LONGER WILL LIKELY KEEP TEMPS UP MORE THAN EXPECTED.
TUESDAY...FORECAST CONFIDENCE HIGH.
BRIEF RIDGING SHOULD KEEP THIS DAY QUIET AND DRY...STILL COLD
THOUGH.
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...FORECAST CONFIDENCE IS
MEDIUM.
ANOTHER MID LEVEL SHORT WAVE ARRIVES FROM THE NORTHWEST TUESDAY
NIGHT AND SLOWLY EXITS WEDNESDAY NIGHT. THIS WILL BRING ANOTHER
CHANCE OF LIGHT SNOW THROUGH THIS PERIOD. AMOUNTS WILL BE ON THE
LIGHT SIDE GIVEN HOW COLD THE AIRMASS WILL BE.
THURSDAY THROUGH SATURDAY...FORECAST CONFIDENCE IS MEDIUM.
WE/RE LOOKING AT HIGH PRESSURE AND QUIET BUT CHILLY WEATHER THIS
PERIOD.
AVIATION/00Z TAFS/...PLENTY OF LIFR CIGS AROUND WITH LIGHT WIND
REGIME...DECENT LOW LEVEL INVERSION WITH SOUNDINGS MOIST UP TO 750
MILLIBARS. EXPECTING LITTLE IMPROVEMENT AS MOISTURE WILL BE
EINFORCED WITH ARRIVAL OF WINTER STORM TONIGHT INTO SUNDAY.
NORTHEAST WINDS WILL INCREASE TONIGHT. SNOW AND A MIX IS EXPECTED AT
THE EVENT ONSET...THIS LIKELY STAYING JUST SOUTH OF KMKE. AFTER 6Z
DEPTH OF COLD AIR BECOMES DEEP ENOUGH TO SUPPORT ALL SNOW. STILL
LOOKING AT A 8Z-15Z TIME FRAME FOR HEAVIEST SNOWFALL ACROSS THE
AREA. GUSTY NORTH WINDS WILL GRADUALLY TURN NORTHWEST AS SUNDAY
WEARS ALONG.
MARINE...NO CHANGES PLANNED TO SMALL CRAFT ADVISORY HEADLINE.
NORTHEAST WINDS WILL RAMP UP TONIGHT WITH LOW PRESSURE PASSING TO
THE SOUTHEAST OF WI. WINDS WILL SHIFT MORE TO THE NORTH ON SUNDAY
AND REMAIN GUSTY. HIGH WAVES ARE EXPECTED AS WELL.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR WIZ056-062>072.
WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR WIZ046-047-051-
052-057>060.
LM...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR LMZ643.
SMALL CRAFT ADVISORY UNTIL 9 PM CST SUNDAY FOR LMZ643>646.
&&
$$
UPDATE...REM
TONIGHT/SUNDAY AND AVIATION/MARINE...COLLAR
SUNDAY NIGHT THROUGH SATURDAY...DAVIS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
900 PM CST SAT DEC 21 2013
.UPDATE...
ISSUED AT 900 PM CST SAT DEC 21 2013
THE MAIN FOCUS THIS EVENING HAS BEEN WITH WHETHER OR NOT A TIER
OF COUNTIES NEEDS TO BE ADDED ONTO THE CURRENT ADVISORY/WARNING.
CURRENTLY...SOME VERY LIGHT FREEZING DRIZZLE HAS BEEN FALLING
ACROSS PORTIONS OF THE AREA IN RESPONSE TO SOME WEAK 280-290K
ISENTROPIC LIFT THAT IS OCCURRING AHEAD OF THE MAIN TROUGH. BEFORE
WE SEE ANY SNOW DEVELOP LOCALLY...THE DRY LAYER BETWEEN 800-600MB
WILL HAVE TO SATURATE OUT. THE 22.01 RAP RH FIELDS SHOW SOME
INCREASING RH IN THAT COLUMN COMING IN FROM THE SOUTHEAST AND
SOUTH AROUND AND AFTER 6Z. THIS COINCIDES FAIRLY WELL WITH WHAT
22.00Z HRRR REFLECTIVITY GRAPHICS SHOW WITH THE SNOW MOVING UP
INTO NORTHEAST IOWA AROUND/AFTER 6Z.
BASED ON THE PATH OF THE 500MB VORT MAX THROUGH NORTHERN ILLINOIS
AND THE CURRENT HEAVY SNOW THAT IS FALLING ACROSS PORTIONS OF
KANSAS...CONFIDENCE IS STILL HIGH IN THE HEAVY SNOW THAT IS
FORECAST TO OCCUR OVERNIGHT INTO TOMORROW MORNING ACROSS THE
WINTER STORM WARNING AREA. IT STILL LOOKS LIKE THE 2AM TO 10AM
TIME FRAME IS WHEN THE HEAVIEST SNOW WILL COME THROUGH WITH SOME
1...MAYBE 2...INCH PER HOUR SNOWFALL RATES IN THIS BAND.
FURTHER TO THE NORTHWEST...THE 22.00Z AND PRIOR RUNS HAVE BEEN
HINTING AT A SECONDARY DEFORMATION BAND SETTING UP ALONG THE
ADVISORY COUNTIES AND POSSIBLE JUST TO THE WEST OF IT. THIS LIFT
IS COMING IN THE 500-300MB LEVELS AND IS OVER THE DRY LAYER
BETWEEN 800-600MB...SO THERE IS THE QUESTION OF WHETHER THE DRY
LAYER WILL BE DEEP ENOUGH TO KEEP ANY SNOW/ICE FROM MAKING IT TO
THE GROUND. 22.01Z RAP SOUNDINGS SHOW THIS DRY LAYER WINNING OUT
THROUGH MUCH OF THE OVERNIGHT HOURS BEFORE BRIEFLY SATURATING UP
ENOUGH TO ALLOW FOR SOME SNOW TO FINALLY OCCUR TOWARD DAYBREAK.
DUE TO THE SHORT LENGTH OF WHEN THIS SNOW COULD FALL...HAVE
DECIDED TO NOT MAKE ANY CHANGES TO THE CURRENT ADVISORY...BUT WILL
UP THE TOTALS AN INCH OR TWO FROM CHARLES CITY IOWA NORTH
NORTHEAST TOWARD BLACK RIVER FALLS WISCONSIN FOR WHERE IT LOOKS
LIKE THIS BAND COULD SET UP. WILL CONTINUE TO WATCH DOWNSTREAM
OBS FOR WHETHER ANY FUTURE ADJUSTMENTS NEED TO BE MADE TO THIS
AREA.
&&
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 300 PM CST SAT DEC 21 2013
MAIN FORECAST CONCERNS THIS PACKAGE...WINTER STORM TO MOVE ACROSS
THE AREA TONIGHT/SUN...LINGERING SNOW CHANCES SUN NIGHT.
DATA ANALYSIS AT 18Z HAD A BROAD AREA OF HIGH PRESSURE OVER CENTRAL
CANADA AND DEEPENING LOW PRESSURE OVER ARKANSAS. PER WV IMAGERY...
SHORTWAVE OF INTEREST FOR TONIGHT/SUNDAY HAS ROUNDED THE BASE OF THE
TROUGH AND COULD BE SEEN LIFTING NORTHEAST ACROSS TX AT MID-DAY.
UPPER MIDWEST UNDER THE INFLUENCE OF THE HIGH TODAY...WITH GENERALLY
QUIET WEATHER BUT MOSTLY CLOUDY TO CLOUDY SKIES WITH ABUNDANT LOW
LEVEL MOISTURE TRAPPED UNDER AN INVERSION NEAR 850MB. MID-DAY TEMPS
ACROSS MUCH OF THE REGION NEAR SEASONAL NORMALS.
21.12Z MODELS LOOK TO HAVE INITIALIZED WITHOUT LARGE ERRORS. MODELS
CONTINUE TO CONVERGE TOWARD A TIGHTER/COMMON CONSENSUS THRU SUN
NIGHT...TOWARD THE EARLIER ECMWF/CAN-GEM RUNS. THIS AS THE AZ/
NORTHERN MEX/WEST TX SHORTWAVE ENERGY LIFTS QUICKLY NORTHEAST
TONIGHT/SUN TO WESTERN QUEBEC BY 00Z MON...AND ENERGY OVER BC/ALB
CARVES OUT A RATHER DEEP TROUGH OVER THE REGION LATER SUN NIGHT.
MODEL DIFFERENCES THAT DO REMAIN IMPACT SNOW AMOUNTS TONIGHT/SUNDAY.
CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED MODELS ALL REASONABLE ON
THE SFC MASS FIELDS ACROSS THE CENTRAL CONUS. PER WV IMAGERY...
MODELS ALL APPEAR GOOD WITH THE SOUTHERN PLAINS SHORTWAVE ENERGY.
BLEND OF THE MODELS LOOKED GOOD WITH THE 12-18Z PRECIP ASSOCIATED
WITH THE MID LEVEL TROUGH AND SFC TROUGH/FRONT FROM THE SOUTHERN
PLAINS LOW THRU OHIO VALLEY. WITH MODELS TRENDING MORE SIMILAR...
TOWARD A TIGHTER COMPROMISE SOLUTION...FAVORED THE MODEL/ENSEMBLE
CONSENSUS. GIVEN THE SNOW AMOUNT DIFFERENCES...AND A SLIGHT TREND
TOWARD DRIER/LESS SNOW...SHORT-TERM FCST CONFIDENCE IS SHY OF GOOD
THIS CYCLE.
IN THE SHORT TERM...MODEL SOUNDINGS SHOWING SATURATION TO ABOUT
800MB AND CLOUD TOP TEMPS IN THE -5C TO -10C RANGE THIS AFTERNOON.
FALLING PRESSURES/DIVERGENCE ALOFT STARTING TO SPREAD ACROSS THE
AREA...PROVIDING A LITTLE LIFT TO THE LOWER LEVELS AND GETTING FEW
REPORTS OF -FZDZ. MODEL SOUNDINGS SHOWING IT TAKES THRU MUCH OF
THE EVENING FOR THE COLUMN TO SATURATE FOR ICE IN THE LOWER CLOUD/
MOISTURE LAYER. AVIATION FORECASTER DID ADD MENTION OF -FZDZ WITH
THE -SN CHANCES TO MUCH OF THE FCST AREA THRU THE EVENING.
VIGOROUS TX SHORTWAVE LIFTS TO NEAR THE IA/MO/IL INTERSECTION BY
12Z SUN...WHILE THE SFC LOW LIFTS TO THE VICINITY OF NORTHWEST OH.
850MB LOW LIFTS ACROSS MO TO NEAR OR EAST OF CHICAGO BY 12Z SUN.
ON THIS TRACK...MUCH OF THE STRONGER/DEEPER LOWER LEVEL THERMO-
DYNAMIC FORCING JUST CLIPS THE SOUTHEAST END OF THE FCST AREA.
BULK OF THE FORCING/LIFT TO PASS ACROSS THE REST OF THE FCST AREA
WILL BE FROM UPPER LEVEL PV ADVECTION/DIVERGENCE/LIFT AHEAD OF THE
VIGOROUS SHORTWAVE AND DIVERGENCE ALOFT BETWEEN AT LEAST SEMI-
COUPLED JET MAXES. PLENTY OF MOIST/UNSTABLE AIR BEING LIFTED NORTH
OF THIS SYSTEM...WITH DYNAMICS/LIFT AHEAD OF THE ADVANCING TROUGH
PRODUCING ABUNDANT CONVECTION/PRECIP NEAR THE SFC TROUGH/FRONT
ACROSS THE MID MS TO OH VALLEYS. THE SLIGHT DROP IN PRECIP
PRODUCTION ACROSS THE AREA TONIGHT/SUN MAY BE TIED TO THIS WALL OF
CONVECTION ROBBING MUCH OF THE INCOMING MOISTURE BEFORE IT WOULD
REACH THE AREA. GFS/ECMWF/NAM NOW BARELY PRODUCE ENOUGH QPF FOR
ADVISORY SNOW AMOUNTS OVER THE SOUTHEAST END OF THE FCST AREA
WHILE CAN-GEM STILL HOLDS ONTO WARNING/ADVISORY AMOUNTS ACROSS THE
SOUTHEAST 1/3 TO HALF OF THE FCST AREA. WITH MUCH OF THE LIFT
ABOVE 850MB AND EVEN 700MB...AND VERTICAL MOTIONS NOT OVERLY
STRONG EXCEPT OVER THE SOUTHEAST END OF THE FCST AREA...HAVING A
HARD TIME SEEING SNOW-WATER RATIOS IN THE 15 TO 20 TO 1 RANGED TO
PRODUCE THE HIGHER SNOWFALL TOTALS. LOWERED SNOW AMOUNTS A
BIT...BUT LEFT THEM IN RANGES TO SUPPORT THE CURRENT ADVISORIES/
WARNINGS...WHICH WILL BE LEFT AS FOR NOW. TIGHTER PRESSURE
GRADIENT AND BRISK NORTHWEST WINDS FOR SOME BLOWING/DRIFTING OF
NEW SNOW WILL ADD THAT TO THE WINTER WEATHER HEADLINES FOR LATER
TONIGHT/MUCH OF SUNDAY.
FORCING/LIFT WITH THIS SHORTWAVE EXITS DURING THE MORNING WITH
ATTENTION QUICKLY TURNING TO THE NORTHERN STREAM SHORTWAVE DROPPING
TOWARD THE AREA. STRONG HGT FALLS TO MOVE ACROSS THE AREA LATER SUN/
SUN NIGHT WITH ANOTHER ROUND OF STRONG PV ADVECTION AND DIVERGENCE/
LIFT ALOFT. MUCH COLDER COLUMN OVER THE AREA BY SUN NIGHT WITH THE
DENDRITIC GROWTH ZONE LOWER...IN THE 850-700MB RANGE. INCREASING
MODEL SIGNAL/CONSENSUS FOR THE FEATURE TO PRODUCE 1 TO PERHAPS 2
INCHES OF SNOW ACROSS THE NORTHEAST 2/3 OF THE FCST AREA SUN
AFTERNOON/NIGHT AND RAISED SNOW CHANCES THESE PERIODS INTO THE 70-80
PERCENT RANGE OVER THAT PORTION OF THE FCST AREA. USED THE MODEL/
ENSEMBLE CONSENSUS FOR LOWS/HIGHS TONIGHT THRU SUN NIGHT...PLENTY OF
CLOUDS THRU SUN NIGHT AND BY LATER TONIGHT STRONGER GRADIENT SFC
WINDS TO KEEP THE BOUNDARY LAYER STIRRED.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 300 PM CST SAT DEC 21 2013
MAIN FORECAST CONCERNS FOR MONDAY THROUGH TUESDAY NIGHT...SNOW
CHANCES WITH NORTHWEST FLOW SHORTWAVES AND TEMPERATURES THRU THE
PERIOD.
21.12Z MODELS IN IMPROVING AGREEMENT AS THE DEEP MID LEVEL TROUGH
MOVES ACROSS THE REGION MONDAY THEN HGTS RISING QUICKLY WITH ITS
PASSAGE AND SHORTWAVE RIDGING BUILDING IN MON NIGHT. CONSENSUS
REMAINS RATHER TIGHT AS THE SHORTWAVE RIDGE QUICKLY PASSES TUE...
THEN THE NEXT STRONG NORTHWEST FLOW TROUGH DROPS INTO THE REGION AND
SENDS MID LEVEL HGTS CRASHING AGAIN. TREND THRU THE PERIOD FAVORS
STRONGER/SLOWER OF THE EARLIER RUNS. FCST CONFIDENCE IN THE MON THRU
TUE NIGHT PERIOD IS AVERAGE TO GOOD THIS CYCLE.
PLENTY OF SFC-600MB MOISTURE...A COLD COLUMN...DEEP/TIGHT CYCLONIC
CONVERGENCE AND A SFC TROUGH COMBINE TO CONTINUE WRINGING OUT SOME
LIGHT SNOW ACROSS MUCH OF THE FCST AREA ON MON...RAISED -SN CHANCE
TO THE 50-70 PERCENT RANGE OVER THE EAST HALF OF THE FCST AREA...
MAINLY DURING THE MORNING AHEAD OF THE MID LEVEL TROUGH AXIS. -SN
CHANCES WANE MON AFTERNOON WITH PASSAGE OF THE 700-500MB TROUGH
AXIS. RATHER SHARP SFC-700MB RIDGE AXIS AND SUBSIDENCE WITHIN IT
BUILDING EAST LATE MON/MON NIGHT SHOULD HELP CLEAR OUT THE CLOUDS
BUT WITH THE SLOWING TREND AMONG THE MODELS...THIS MAY NOT OCCUR
UNTIL LATE MON NIGHT OVER THE EAST END OF THE FCST AREA. MORE CLOUDS
FOR MORE OF THE NIGHT MON NIGHT TO HAVE AN IMPACT ON LOW TEMPS.
WARMER MODEL CONSENSUS LOWS MON ESPECIALLY OVER THE EAST HALF OF THE
FCST AREA LOOK GOOD. ANY SHOT AT CLEAR SKIES/SOME SUNSHINE APPEAR
SHORT LIVED AS SFC-700MB RIDGE AXIS PASSES QUICKLY WITH INCREASING
LOWER LEVEL WARM ADVECTION AND DEEPER MOISTURE AHEAD OF THE NEXT
TROUGH SPREADING RAPIDLY ACROSS THE REGION ON TUE. GIVEN THE DEPTH/
STRENGTH OF THE UPWARD MOTION AND MOISTURE INCREASE SIGNAL...-SN
CHANCES MOVE QUICKLY BACK INTO THE FCST AREA TUE AFTERNOON. WITH THE
TIGHTER MODEL CONSENSUS...RAISED -SN CHANCES INTO THE 40-60 PERCENT
RANGE FOR TUE NIGHT...WITH 1 TO 2 INCHES OF LIGHT SNOW LOOKING
LIKELY FOR MUCH OF THE FCST AREA CHRISTMAS EVE NIGHT. USED A BLEND
OF THE NUMERICAL TEMPS GUIDANCE FOR HIGHS/LOWS MON-TUE NIGHT.
FOR CHRISTMAS DAY THROUGH SATURDAY.../DAYS 4 TO 7/...
21.00S AND 21.12Z MEDIUM RANGE MODELS IN DECENT AGREEMENT FOR A
RATHER VIGOROUS SHORTWAVE TROUGH TO BE MOVING ACROSS THE UPPER
MIDWEST ON WED WITH AN INCREASING SIGNAL FOR A SECONDARY SHORTWAVE
TO DROP ACROSS THE REGION WED NIGHT. GOOD CONSENSUS FOR BROAD
LONGWAVE TROUGHING TO REMAIN OVER CENTRAL/EASTERN NOAM FRI/SAT...
WITH PLENTY OF DIFFERENCES ON SMALLER SCALE SHORTWAVES EMBEDDED IN
THE FLOW. SOME CONSENSUS FOR A STRONGER/TRACKABLE SHORTWAVE TROUGH
TO BE DROPPING INTO THE NORTHERN PLAINS SAT. ALL IN ALL...DAY 4-7
FCST IS AVERAGE.
LIGHT SNOW REMAINS IN THE FCST FOR CHRISTMAS DAY/WED NIGHT. THE MAIN
LOWER LEVEL THERMO-DYNAMIC FORCING AND DIVERGENCE ALOFT FROM THE TUE
NIGHT SHORTWAVE WILL BE PASSING EAST OF THE AREA WED MORNING...WITH
DECREASING -SN CHANCES THRU THE DAY. GFS/ECMWF THEN DROP A RATHER
VIGOROUS SECONDARY SHORTWAVE SOUTHEAST ACROSS THE AREA WED NIGHT
WITH ANOTHER ROUND OF STRONGER DIVERGENCE/LIFT ALOFT. SOUNDINGS/X-
SECTIONS SHOWING PLENTY OF MOISTURE IN THE COLUMN FOR THIS LIFT TO
WRING OUT SOME -SN...EVEN WITH LESSER LOW LEVEL SUPPORT/LIFT AND
LOWER OVERALL PW VALUES. APPEARS THE AREA GETS A BREAK FROM THE
PRECIP/-SN BY LATER THU AND FOR FRI AS HGTS RISE A BIT AND A
LARGER/DRY/COLD SFC HIGH PRESSURE RIDGE BUILDS ACROSS THE REGION.
THIS HIGH MOVES EAST RATHER QUICKLY FRI. A MDT/STRONG ROUND OF LOWER
LEVEL WARM ADVECTION TO SPREAD INTO/ACROSS THE AREA LATER FRI THRU
SAT...AHEAD OF THE NEXT STRONGER SFC-MID LEVEL TROUGH PROGGED TO
DROP INTO THE NORTHERN PLAINS. LOWER LEVEL MOISTURE INCREASE IN THIS
FLOW APPEARS DELAYED INTO FRI NIGHT/SAT. MAY YET NEED A -SN CHANCE
AGAIN BY SAT BUT WILL STAY WITH THE DRY MODEL/ENSEMBLE CONSENSUS FOR
NOW UNTIL A CLEARER SIGNAL IS SEEN. TEMPS TO REMAIN BELOW NORMAL FOR
WED-SAT WITH THE AREA UNDER THE NORTHWEST FLOW ALOFT. SOME WELL
BELOW NORMAL TEMPS WITH THE LARGER/COLD HIGH FOR THU/FRI. MODEL/
ENSEMBLE CONSENSUS FOR HIGHS/LOWS IN THE WED-SAT PERIOD LOOKS TO
HAVE THIS WELL TRENDED.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 549 PM CST SAT DEC 21 2013
MVFR CEILINGS WILL DROP TO IFR AS SNOW BEGINS OVERNIGHT. THERE IS
THE POSSIBILITY THAT THEY COULD DROP EARLIER AS SOME FREEZING
DRIZZLE POTENTIALLY MOVES IN THIS EVENING...BUT CONFIDENCE IS NOT
HIGH IN THIS SCENARIO. AS THE SNOW BEGINS...LSE WILL LIKELY SEE
THE HEAVIER SNOW RATES AND THUS LOWER VISIBILITY. EXPECT THAT IT
WILL MAINLY BE AROUND 1-2SM THOUGH SOME BRIEF DROPS TO A HALF MILE
CAN NOT BE RULED OUT. CONDITIONS ARE EXPECTED TO IMPROVE TOMORROW
AFTERNOON AS THE SYSTEM TRACKS TO THE NORTHEAST OF THE REGION
THOUGH SOME LIGHT SNOW SHOWERS WILL LIKELY LINGER BEHIND IT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR WIZ053.
WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR WIZ054-055-061.
WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR WIZ034-041-042.
WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR WIZ043-044.
MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR MNZ096.
IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR IAZ010-011-019.
WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR IAZ029-030.
&&
$$
UPDATE...HALBACH
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
305 PM CST FRI DEC 20 2013
.SHORT TERM...(TONIGHT THROUGH SATURDAY NIGHT)
ISSUED AT 305 PM CST FRI DEC 20 2013
MAIN FORECAST CONCERNS THIS PACKAGE...-FZDZ/-SN LATE THIS
AFTERNOON...IMPENDING WINTER STORM MOVING IN SATURDAY NIGHT.
18Z DATA ANALYSIS HAD LOW PRESSURE OVER CENTRAL IL/NORTHERN INDIANA
ALONG THE FRONTAL BOUNDARY...WITH A TROUGH BACK TO NEAR KFSD. WEAK
SHORTWAVES CONTINUED TO RIPPLE THRU THE WEST-SOUTHWEST FLOW ALOFT
OVER THE REGION. THIS COMBINED WITH SOME WEAK 925-700MB WARM
ADVECTION/ISENTROPIC LIFT CONTINUED TO PRODUCE SOME LIGHT RADAR
REFLECTIVITY RETURNS AND SCATTERED SFC OBS WITH VERY LIGHT SNOW.
SOME MIXED/FREEZING PRECIP TYPES OVER EASTERN IA INTO FAR SOUTHERN
WI/NORTHERN IL WHERE THERE WAS ABOVE 0C AIR ALOFT OR LOWER MOISTURE
WAS TOO SHALLOW FOR ICE IN THE CLOUDS.
NO SIGNIFICANT ERRORS NOTED WITH 20.12Z MODEL INITIALIZATIONS.
SOLUTIONS VERY SIMILAR FOR THE AREA TONIGHT/SAT...THEN DIVERGE WITH
THE ARRIVE/AMOUNT OF SNOW SAT NIGHT. NAM NOW FASTEST/MOST ROBUST/
FURTHEST NORTHWEST WITH THE SYSTEM...GFS SLOWER/DRIER WITH CAN
GEM/ECMWF IN THE MIDDLE. ENOUGH DIFFERENCES THAT GFS KEEPS THE FCST
AREA DRY THRU 06Z SUN WHILE NAM SPREADS SNOW ACROSS NEARLY THE
ENTIRE FCST AREA BY THAT TIME. CHECK OF OBS VS. MODEL DATA AT 18Z
SHOWED ALL TO BE REASONABLE WITH THE CENTRAL CONUS MASS FIELDS.
MODELS ALSO DOING A DECENT JOB WITH THE LIGHT PRECIP ACROSS THE
REGION. PER WV IMAGERY...MODELS ALL APPEAR GOOD WITH THE SHORTWAVE
FEATURES OVER NOAM/EASTERN PAC. NO ONE REASON TO FAVOR ONE MODEL
OVER THE OTHER AND FAVORED THE MODEL/COMPROMISE...WHICH IS SIMILAR
TO THE ECMWF/CAN GEM THIS CYCLE. SHORT TERM FCST CONFIDENCE GOOD
TONIGHT/SAT THEN AVERAGE SAT NIGHT GIVEN THE MODEL DIFFERENCES.
IN THE SHORT TERM...WEAK LOWER LEVEL WARM ADVECTION/ISENTROPIC LIFT
MOVES EAST/SOUTH OF THE FCST AREA LATE THIS AFTERNOON WITH WHAT
SHOULD BE A QUICK END TO THE LIGHT PRECIP THIS EVENING. HOWEVER...
DID CONTINUE WITH SOME SMALL -ZL/-SN CHANCES OVER MAINLY THE EAST
HALF OF THE FCST AREA INTO THE EARLY EVENING AS A COUPLE OF THE HI-
RES MODELS PRODUCE SOME SPOTTY/LIGHT QPF IN THE 00-03Z PERIOD. SHORT-
TERM FORECASTER HAS ALREADY EXTENDED THE FREEZING RAIN ADVISORY TO
00Z ACROSS THE SOUTHEAST END OF THE FCST AREA WHERE REPORTS INDICATE
FREEZING DRIZZLE CONTINUES TO BE AN ISSUE. SFC-850MB GRADIENT
REMAINS ON THE LIGHT SIDE TONIGHT...WITH LITTLE IN THE WAY OF
ADVECTION TO MOVE THE LOWER LEVEL MOISTURE/CLOUDS OUT OF THE AREA.
CLOUDS REMAIN STUCK OVER THE ARE THRU SAT...AND WILL HAVE A MUTING
EFFECT ON THE DIURNAL TEMP RANGE TONIGHT/SAT.
MODEL DIFFERENCES SAT NIGHT HAVE AN IMPACT ON THE SENSIBLE WEATHER.
12Z NAM WAS FASTEST FURTHEST NORTHWEST WITH THE QPF/SNOW AS THE MID
LEVEL TROUGH/SHORTWAVE LIFTS INTO THE REGION SAT NIGHT...AS IT IS
FURTHER NORTHWEST WITH THE WAVE AND 500-300MB PV ADVECTION AHEAD OF
IT. 20.18Z NAM HAS COME MORE IN LINE WITH ECMWF/CAN-GEM CONSENSUS.
MAIN LOWER LEVEL THERMO-DYNAMIC FORCING/DEFORMATION BAND OF LIFT IS
ACTUALLY RATHER CONSISTENT AMONG THE MODELS...MAINLY CLIPPING THE
SOUTHWEST END OF THE FCST AREA. DEEPEST LIFT PASSES MAINLY ACROSS
AREAS SOUTH OF A KOLZ-KPDC-KDLL LINE. NORTH OF THIS LINE...FORCING/
LIFT PROGGED TO MAINLY AT/ABOVE 700MB...NOT CONDUCIVE TO HIGH SNOW-
WATER RATIOS AND HEAVY SNOW. WHERE CONFIDENCE REMAINS HIGHEST AND
MODELS PAINT 1/4 TO 1/2 INCH PLUS OF QPF...WITH SNOW-WATER RATIOS IN
THE 15 TO 1 RANGE AND 4 TO 8 INCHES OF SNOW POSSIBLE...WILL UPGRADE
THE WATCH TO WARNING FOR GRANT/ CRAWFORD/RICHLAND AND CLAYTON
COUNTIES. WILL LEAVE WATCH FOR THE REMAINING COUNTIES FOR NOW DUE
SOME UNCERTAINTY WITH THE SFC-MID LEVEL TROUGH TRACK AND QPF IS
MAINLY 1/4 INCH OR LESS. IN TIME THESE WATCH COUNTIES PLUS A FEW
MORE ALONG/SOUTHEAST OF A TOMAH WI TO DECORAH AND NEW HAMPTON IA
LINE LIKELY TO NEED A WINTER WEATHER ADVISORY. STILL PLENTY OF TIME
FOR THAT AND CHANCE TO LOOK AT A COUPLE MORE MODEL RUNS...WHICH
HOPEFULLY CONVERGE ON A TIGHTER CONSENSUS. GENERALLY MADE ONLY MINOR
CHANGES TO THE FCST GRIDS FOR TONIGHT THRU SAT NIGHT. MODEL/ENSEMBLE
CONSENSUS LOWS/HIGHS FOR THESE PERIODS QUITE REASONABLE.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 305 PM CST FRI DEC 20 2013
MAIN FORECAST CONCERNS FOR SUNDAY THRU MONDAY NIGHT...WINTER STORM
CONTINUING SUNDAY...LINGERING -SN/FLURRY CHANCES SUN NIGHT THRU MON
NIGHT.
20.12Z MODELS IN RATHER GOOD AGREEMENT FOR THE SHORTWAVE OVER
IA/IL/MO AT 12Z SUN TO BE IN QUEBEC BY 00Z MONDAY AND RATHER
SHARP/DEEP COLD CORE TROUGHING TO BE OVER THE REGION SUN NIGHT INTO
MON NIGHT. SOME MODEL DIFFERENCES ON HOW QUICKLY THIS TROUGH MOVES
EAST OF THE REGION MON NIGHT BUT MODEL CONSENSUS IS IMPROVING AND
FAVORS A COMPROMISE OF THE PREVIOUS RUNS. FCST CONFIDENCE THIS
PERIOD IS AVERAGE TO GOOD.
WITH THE FAST MOVEMENT OF THE MID LEVEL TROUGH SUNDAY...LOWER LEVEL
THERMO-DYNAMIC FORCING AND DYNAMIC LIFT/DIVERGENCE ALOFT MOVES
QUICKLY EAST OF THE AREA. CARRIED HIGHEST SNOW CHANCES SUN MORNING
OVER THE SOUTHEAST HALF OF THE FCST AREA. THE NORTHERN STREAM
SHORTWAVE DROPS TOWARD THE AREA FOR THE AFTERNOON...WITH ANOTHER
ROUND OF 500-300MB PV ADVECTION OVER THE TOP OF DEEP CYCLONIC
FLOW...AN INVERTED SFC TROUGH AND PLENTY OF SFC-700MB MOISTURE.
RAISED -SN CHANCES INTO THE 40-60 PERCENT RANGE...HIGHEST OVER THE
NORTHEAST SIDE OF THE FCST AREA. NOT EXPECTING MUCH FOR SNOW
ACCUMULATIONS SUN AFTERNOON...BUT APPEARS THERE WILL BE SOME SNOW IN
THE AIR ALONG WITH NORTHWEST WINDS OF 10-20MPH GUSTING 20-30 MPH FOR
SOME BLOWING/DRIFTING SNOW. WINTER STORM WATCH/WARNING HEADLINES TO
00Z MON STILL LOOK GOOD.
THE SFC THRU MID LEVEL TROUGH PIVOTS OVER THE AREA SUN NIGHT...WITH
DEEP CYCLONIC FLOW AND COLD ADVECTION TO PUT THE SQUEEZE ON THE
MOISTURE IN THE COLUMN. -SN/FLURRIES TO CONTINUE OVER MUCH OF THE
AREA SUN NIGHT AND RAISED PRECIP CHANCES MOSTLY INTO THE 15-40
PERCENT RANGE...AGAIN HIGHEST OVER THE NORTHEAST SIDE OF THE FCST
AREA. WITH THE DEEP/COLD MID LEVEL TROUGH OVER THE AREA YET
MON...CONTINUED SMALL -SN CHANCES FOR MUCH OF THE AREA MON. TROUGH
AXIS MOVES EAST OF THE AREA MON NIGHT WITH COLD SFC HIGH PRESSURE
BUILDING IN. A COUPLE OF COLDER NIGHTS SUN/MON WITH 925MB TEMPS IN
THE -14C TO -20C RANGE AT 12Z MON/TUE. CLOUDS/BOUNDARY LAYER WINDS
SHOULD KEEP LOWS FROM BOTTOMING OUT TOO FAR SUN NIGHT. HOWEVER SOME
CLEARING EXPECTED MON NIGHT WITH LIGHT WINDS UNDER THE SFC RIDGE
AXIS. LOWS MON NIGHT TRENDING TO THE -10F TO -15F RANGE. USED A
MODEL/ENSEMBLE BLEND FOR HIGHS/LOWS IN THE SUN-MON NIGHT PERIOD.
FOR TUESDAY THRU FRIDAY.../DAYS 4 TO 7/...
20.00Z AND 20.12Z MEDIUM RANGE MODELS IN REASONABLE AGREEMENT FOR
LONGWAVE RIDGING TO PERSIST ALONG THE WEST COAST AND LONGWAVE
TROUGHING TO REMAIN OVER CENTRAL/EASTERN NOAM THRU THE CHRISTMAS
HOLIDAY PERIOD. MODELS TRENDING TOWARD A ROUGH COMPROMISE OF THE
EARLIER RUNS WITH THE LONGER WAVE/MORE TRACKABLE FEATURES. THIS
LEAVES THE NORTH-CENTRAL CONUS UNDER NORTHWEST FLOW ALOFT...BUT
FOR SOME TRANSIENT SHORTWAVE RIDGING TUE...WITH PLENTY OF
INHERENTLY DIFFICULT TO TIME AND TRACK SHORTWAVES MOVING THRU THAT
FLOW LATER TUE THRU FRI. DECENT CONSISTENCY FOR THE SHORTWAVE
RIDGING TO BE MOVING ACROSS TUE...AHEAD OF A STRONGER SHORTWAVE
TROUGH TO DROP INTO/ACROSS THE NORTH-CENTRAL CONUS TUE NIGHT/WED.
RATHER DEEP/COLD MID LEVEL TROUGHING TO THEN REMAIN OVER THE UPPER
MIDWEST FOR THU/FRI. DAY 4-7 FCST CONFIDENCE IS AVERAGE THIS
CYCLE.
SHORTWAVE RIDGING ALOFT MOVES QUICKLY EAST ACROSS THE AREA TUE.
MDT/STRONG LOWER LEVEL WARM ADVECTION AND 280K-300K ISENTROPIC LIFT
SPREADS ACROSS THE AREA ON THE BACK SIDE OF THE SFC-MID LEVEL RIDGE
AXIS...ALONG WITH PW VALUES QUICKLY INCREASING TO 0.4 TO 0.5 INCH
FOR TUE AFTERNOON/EVENING AHEAD OF THE SFC-MID LEVEL TROUGH AXIS.
COLUMN LOOKS TO REMAIN COLD ENOUGH FOR ANY PRECIP TUE/TUE NIGHT AS
SNOW. IF PRESENT MODEL TRENDS CONTINUE/CONSENSUS TIGHTENS...APPEARS
SNOW CHANCES TUE AFTERNOON/EVENING WILL NEED TO BE RAISED WITH
PERHAPS 1 TO 2 INCHES OF SNOW CHRISTMAS EVE. THIS SHORTWAVE TROUGH
PASSES...BUT ANOTHER DEEP COLD CORE TROUGH SETS UP SHOP OVER THE
UPPER MIDWEST FOR WED-FRI. AGAIN PLENTY OF SHORTWAVE TIMING/STRENGTH
DETAIL DIFFERENCES FOR FEATURES TO BE ROTATING THRU THIS TROUGH IN
THE DAY 5-7 PERIOD. GIVEN THE COLD COLUMN...DEEP CYCLONIC FLOW AND
THE FCST AREA ON THE CYCLONIC SIDE OF THE 500-300MB JET...THERE IS
AN ARGUMENT FOR SMALL -SN CHANCES THRU MUCH OF THE WED-FRI PERIOD.
GIVEN THE TIMING/DETAIL DIFFERENCES... STAYED WITH THE MODEL/
ENSEMBLE CONSENSUS -SN CHANCES FOR NOW. GIVEN AVERAGE AT BEST
CONFIDENCE IN THE DETAILS...MODEL/ENSEMBLE CONSENSUS FOR TUE-FRI
HIGHS/LOWS APPEARS WELL TRENDED.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1146 AM CST FRI DEC 20 2013
THE LIGHT PRECIPITATION HAS MOVED OFF TO THE EAST OF BOTH TAF SITES.
CONDITIONS HAVE TEMPORARILY IMPROVED TO VFR BUT DO NOT EXPECT THIS
TO LAST LONG. LOTS OF MVFR WITH SOME IFR JUST OFF TO THE SOUTHWEST
AND THE CURRENT FLOW PATTERN SHOULD BRING THIS BACK OVER BOTH
AIRPORTS THIS AFTERNOON AND WILL SHOW MVFR BY THE MIDDLE OF THE
AFTERNOON. SOME POTENTIAL FOR ADDITIONAL PRECIPITATION TO DEVELOP
THIS AFTERNOON BUT IF THE 20.15Z RAP IS CORRECT...THIS SHOULD STAY
TO THE SOUTH. WITH THE BROAD SOUTHWEST FLOW...LOOKS LIKE ONCE THE
MVFR CONDITIONS MOVE BACK IN...THEY SHOULD PERSIST THROUGH THE
REMAINDER OF THE PERIOD AND COULD EVEN GO DOWN TO IFR OVERNIGHT AT
KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR WIZ054-
055-061.
WINTER STORM WARNING FROM 6 PM SATURDAY TO 6 PM CST SUNDAY FOR
WIZ054-055-061.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ043-044-053.
MN...NONE.
IA...FREEZING RAIN ADVISORY UNTIL 6 PM CST THIS EVENING FOR IAZ011-
029-030.
WINTER STORM WARNING FROM 6 PM SATURDAY TO 6 PM CST SUNDAY FOR
IAZ030.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR IAZ011-029.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION.....04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1146 AM CST FRI DEC 20 2013
.UPDATE...
ISSUED AT 1146 AM CST FRI DEC 20 2013
THE BULK OF THE PRECIPITATION HAS SHIFTED OFF TO THE EAST OF THE
AREA BY LATE THIS MORNING. STILL SOME LIGHT SNOW OVER CENTRAL
WISCONSIN WITH SOME SLEET OR FREEZING DRIZZLE ACROSS THE SOUTH.
EXPECT THAT MOST OF THIS WILL END EARLY THIS AFTERNOON BUT COULD
SEE SOME MORE GENERATE BY MID AFTERNOON ACROSS THE SOUTH. THE RAP
SHOWS THE WEAK SHORT WAVE TROUGH COMING OUT OF EASTERN NEBRASKA TO
TRACK TOWARD THE AREA TO POSSIBLY PRODUCE THE AFTERNOON
PRECIPITATION. IF INDEED THIS DOES OCCUR...THE RAP BUFKIT
SOUNDINGS WOULD SUGGEST THERE WOULD BE LITTLE TO NO ICE IN THE
CLOUDS FOR THE POTENTIAL OF MORE FREEZING DRIZZLE. WILL LET THE
FREEZING RAIN ADVISORY ALONG INTERSTATE 90 EXPIRE AT 18Z AND
CONTINUE THROUGH THE MIDDLE OF THE AFTERNOON FARTHER SOUTH. MAY BE
NECESSARY TO EXTEND THE ADVISORY ACROSS THE SOUTH IF ADDITIONAL
FREEZING DRIZZLE DEVELOPS.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM CST FRI DEC 20 2013
FREEZING DRIZZLE/RAIN HAVE CAUSED SOME PROBLEMS FROM SLIGHTLY
NORTH OF I-90 IN WI...WEST TO JUST OUTSIDE OF ROCHESTER DOWNTOWN
AREA...THEN SOUTH. ACCIDENTS WERE PLENTIFUL...ROAD CREWS HAVE
BEEN OUT WORKING. THE CHALLENGE NOW IS WHAT WILL TODAY LOOK LIKE
AND WHAT TO DO WITH THE IMPACT AND ADVISORY.
GOES WATER VAPOR SHOWING SHORTWAVE TROUGH ENERGY ON A NW-SE AXIS
CENTERED NEAR ABOUT TOPEKA...RIDING NORTHEAST AT THE AREA.
PRESSURES HAVE BEEN RISING OVER THE FORECAST AREA AND COLD AIR
ADVECTION IS DECREASING TEMPERATURES /ABOUT 1F PER HOUR/ DESPITE
SOME PRECIPITATION. TO THE SOUTH ALONG THE FRONTAL BOUNDARY...FROM
THE QUAD CITIES TO SOUTH OF CHICAGO...SURFACE PRESSURES HAVE BEEN
WEAKLY FALLING WITH UPPER WAVE FORCING. SURFACE LOW CENTER IS
CLOSER TO WICHITA AT 08Z. WEAK 700-600MB-CENTERED FRONTOGENETIC
FORCING IS LOCATED ACROSS THE NORTHERN FORECAST ARE YIELDING THE
LINEAR SNOW BAND. THIS HAS SEEDED THE LOW-LEVEL 3-4KFT SUPERCOOLED
LIQUID LAYER /FINALLY/ TO CHANGE THE FZDZ/FZRA TO SNOW.
THE TREND TODAY IN THE RAP FRONTOGENESIS IS TO SHIFT
EASTWARD FROM ABOUT WHERE IT IS NOW...WITHOUT MUCH MORE SOUTHWARD
PROGRESSION...EXITING BY 15Z. 20.06Z NAM HAS VERY SIMILAR
GUIDANCE...HOWEVER THE BAND WOULD SHIFT A BIT FURTHER SOUTH. SINCE
THIS IS THE SEEDER CLOUD...IT DETERMINES THE NORTHERN EXTENT OF
THE FZRA/FZDZ AREA. TO THE SOUTH...ABOUT A 2KM DEEP SUPERCOOLED
LIQUID LAYER EXISTS. RADAR HAS SHOWN SOME DECREASE IN EITHER THE
DEPTH OR LIQUID DROP SIZE OVER THE PAST HOURS IN THE DRIZZLE LAYER
WITH LESS REFLECTIVITY. THIS MAKES FOR PAUSE ON THE ADVISORY. BUT ANOTHER
AREA OF FZRA SHOWERS ARE HEADING IN FROM ERN IOWA...WITH MORE INTO
NRN MO...SO NO SHORTAGE OF INSTABILITY SHOWERS HEADING THIS WAY.
WITH UPSTREAM ENERGY AND LIFT SHIFTING INTO THE AREA...FELT THE
NEED TO EXTEND /IN TIME/ THE FREEZING RAIN ADVISORY...SOUTH OF
THE SNOW BAND...WHERE MORE ICE CAN BE EXPECTED THIS MORNING. WHILE
THE LIFT IS NOTHING LIKE LAST EVENING...THE SURFACE LOW SHIFTING
TO THE SOUTH OF THE AREA WITH DEFORMATION IN THE LOW-LEVELS OVER
NERN IA AND SRN WI MEAN FZRA/FZDZ COULD CONTINUE. MODEL GUIDANCE
ALSO SUGGESTS A WEAK INVERTED TROUGH EMANATING NW FROM THE
SURFACE LOW TO ENHANCE LOW-LEVEL VERTICAL MOTION...ENHANCING CLOUD
DROP GROWTH FOR DRIZZLE. THE LATEST HRRR RUNS HAVE THIS
SUGGESTION...ESPECIALLY LATER ACROSS THE SOUTHERN COUNTIES. THE
SNOW BAND SHOULD ONLY MOVE ABOUT ONE MORE COUNTY SOUTH BEFORE
SHIFTING EAST...AND AGAIN ALLOWING FOR AN ALL LIQUID PRECIPITATION
TYPE. HOWEVER...BEING FURTHER NORTH...THE LIFT IS SOMEWHAT MORE
LIMITED AND THE THREAT ALSO MORE LIMITED /I-90 ROUGHLY/.
THEREFORE...THINK THERE IS ADDITIONAL THREAT FOR FREEZING
PRECIPITATION...ESPECIALLY ACROSS THE SOUTH...THROUGH THE DAY.
WILL EXTENDED THE FREEZING RAIN ADVISORY IN EXTREME NERN IA AND
SWRN WI UNTIL 3PM...AND AREAS NORTH UNTIL 18Z. WILL CANCEL THE
FREEZING RAIN ADVISORY IN AREAS IT IS NOW SNOWING. CONFIDENCE IS
LOW IN THAT NORTHERN AREA...IF THERE WILL BE ENOUGH VERTICAL
MOTION TO CAUSE FZDZ TODAY...BUT IF NEEDED IT CAN BE CANCELLED
EARLY. ICING LOOKS TO BE ABOUT ANOTHER 0.05 INCHES ACROSS THE
SOUTHERN AREA...BEFORE DIMINISHING LATER.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 405 AM CST FRI DEC 20 2013
SATURDAY SEEMS TO BE AN IN BETWEEN DAY BEFORE THE STRONG CYCLONE
OVER THE SWRN U.S. CURRENTLY...SHIFTS TOWARD THE GREAT LAKES.
CLOUD TO GROUND LIGHTNING STRIKES WERE SEEN OVERNIGHT IN AZ WHICH
IN THE WEST...USUALLY HAPPENS ONLY WITH THE STRONGEST IMPULSES. SO
THIS IS A NICE SHORTWAVE TROUGH. THERE ARE A NUMBER OF FAVORABLE
DYNAMICS WITH THIS SYSTEM THAT SHIFT IN...INCLUDING AN INTENSE
160KT+ JET THAT DEVELOPS OVER SRN CANADA AS THE RIDGE BUILDS
DOWNSTREAM OF THE SHORTWAVE EJECTING INTO THE PLAINS. THIS IS
CLASSIC FOR MIDWESTERN HEAVY SNOWFALL CLIMATOLOGY. THIS PLACES A
VERY FAVORABLE ENTRANCE REGION OVER IL/SRN WI SAT NIGHT AND
SUNDAY. A VERY WARM AND MOIST SECTOR /SPC MDT RISK/ WILL BE RIDING
NORTH OUT OF THE GULF ON 50-60KT LOW-LEVEL WINDS AS INFLOW TO THE
FORCING...WHICH IS STRONG QVECTOR CONVERGENCE ALOFT AS
EXPECTED...TO THE SOUTHEAST. THIS STORM WILL PRODUCE HEAVY
SNOWFALL...THE QUESTION IS LOCATION.
WHILE THE WPC WINTER WEATHER DESK CONFIDENCE IS LOWER...IT SEEMS
THE MODELS ARE DRAWING IN ON A SOLUTION THAT WOULD PLACE THE HEAVY
SNOW BAND JUST INTO GRANT COUNTY. THIS WAS VERY CLOSE TO THE
ONGOING FORECAST SO REALLY ONLY MINOR CHANGES WERE MADE. THE NAM
SOLUTIONS STILL SEEM OUT TO LUNCH COMPARED TO THE OTHER
DETERMINISTIC MODELS...A DRY AND EAST OUTLIER. OVERALL...WILL
KEEP THE WATCH UNTIL CONFIDENCE GROWS ON THE LOCATION...BUT THE
REGION WILL SEE A 7-10 INCH SNOW BAND FROM THIS SYSTEM.
WILL BE MONITORING FOR POSSIBLE CHRISTMAS DAY WEATHER ON THE WARM
AIR ADVECTION SHIFTING IN...AFTER THE MONDAY AND MONDAY NIGHT
COOL DOWN POST STORM. THE 20.00Z ECMWF IS A BIT MORE AGGRESSIVE ON
HOLIDAY WEATHER...WE WILL SEE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)
ISSUED AT 1146 AM CST FRI DEC 20 2013
THE LIGHT PRECIPITATION HAS MOVED OFF TO THE EAST OF BOTH TAF
SITES. CONDITIONS HAVE TEMPORARILY IMPROVED TO VFR BUT DO NOT
EXPECT THIS TO LAST LONG. LOTS OF MVFR WITH SOME IFR JUST OFF TO
THE SOUTHWEST AND THE CURRENT FLOW PATTERN SHOULD BRING THIS BACK
OVER BOTH AIRPORTS THIS AFTERNOON AND WILL SHOW MVFR BY THE MIDDLE
OF THE AFTERNOON. SOME POTENTIAL FOR ADDITIONAL PRECIPITATION TO
DEVELOP THIS AFTERNOON BUT IF THE 20.15Z RAP IS CORRECT...THIS
SHOULD STAY TO THE SOUTH. WITH THE BROAD SOUTHWEST FLOW...LOOKS
LIKE ONCE THE MVFR CONDITIONS MOVE BACK IN...THEY SHOULD PERSIST
THROUGH THE REMAINDER OF THE PERIOD AND COULD EVEN GO DOWN TO IFR
OVERNIGHT AT KRST.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR WIZ054-
055-061.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ043-044-053>055-061.
MN...NONE.
IA...FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR IAZ011-
029-030.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR IAZ011-029-030.
&&
$$
UPDATE...04
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...04
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1117 AM CST FRI DEC 20 2013
.UPDATE...KEEPING FREEZING RAIN ADVISORY HEADLINES AS IS. WILL LET
NORTH EXPIRE AT NOON AS COLDER AIR MORE FIRMLY IN PLACE THERE.
STILL CONCERNED THAT MID LEVEL DRYING MAY RESULT IN SOME SPOTTY
FREEZING DRIZZLE THERE...BUT BY AND LARGE CAN RELEASE THE ADVISORY
AT THE GOING NOON END TIME. ADDITIONAL ICING EXPECTED IN THE
SOUTHERN CWA WITH NEXT SURGE RIDING NORTH FROM ILLINOIS. SOME
AREAS HAVE GONE ABOVE IN THE FAR SOUTHEAST AND CLOSE TO THE LAKE.
WINTER STORM STILL LOOKING ON TRACK FOR SATURDAY NIGHT AND SUNDAY.
THE 12Z NAM CAME IN WITH A MORE WESTWARD TRACK PLACING HEAVIER
SNOW A BIT FURTHER WEST IN THE CWA. BUT WE SAW THIS TREND WITH THE
ECMWF AND IT REVERTED BACK TO THE MORE CONSISTENT LOOK OF THE GFS.
RIGHT NOW A GFS/ECMWF TRACK IS PREFERRED. 12Z GFS HAS STAYED THE
SAME AND WILL AWAIT THE ECMWF TO RAISE CONFIDENCE FURTHER IN THIS
SCENARIO. BUT ALL IN ALL LIKE THE PLACEMENT OF THE AMOUNTS AT THIS
TIME.
PC
&&
.AVIATION/18Z TAFS/...MAIN ISSUE WILL BE AFTERNOON AND EARLY
EVENING ICING WITH NEXT SURGE OF PRECIP COMING UP FROM ILLINOIS.
WILL KEEP CIGS AT IFR LEVELS THIS FORECAST PERIOD. QUIETER
CONDITIONS TAKE HOLD LATER TONIGHT INTO SATURDAY WITH BRIEF
RIDGING. WINTER STORM STILL ON TRACK FOR SATURDAY NIGHT INTO
SUNDAY.
PC
&&
.MARINE...SUSTAINED NORTHEAST WINDS ARE AT TIMES GUSTING TO 25
KNOTS WITH SOME HIGHER WAVES OVER 4 FEET. SO WILL MAINTAIN
SMALL CRAFT ADVISORY.
PC
&&
.PREV DISCUSSION... /ISSUED 351 AM CST FRI DEC 20 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH
SURFACE LOW PRESSURE WILL SLOWLY MOVE ACROSS CENTRAL IL AND IN
TODAY. THE 850MB BAROCLINIC ZONE WILL REMAIN STATIONARY OVER
SOUTHERN WI...WITH THE SURFACE AND 925MB FRONT OVER NORTHERN IL.
SURFACE TEMPS WILL REMAIN BELOW FREEZING TODAY EXCEPT FOR RIGHT
ALONG THE SHORELINE.
A PERSISTENT DRY LAYER FROM 10-15 KFT IS EXPECTED TO HANG IN THERE
THROUGH THE DAY...POSSIBLY MOISTENING UP LATE THIS AFTERNOON. THIS
MEANS THAT SATURATED...SUB-FREEZING CONDITIONS FROM THE GROUND UP TO
AROUND 8KFT TODAY WILL CONTINUE TO PRODUCE LIGHT FREEZING
DRIZZLE. IF THE DEEPER SATURATION CAN OCCUR TO GET SOME SNOW
PRODUCTION...THEN SNOW COULD MIX IN WITH THE FREEZING DRIZZLE/RAIN
THIS AFTERNOON.
AS FOR FORCING...THE STRONGER 850-700MB WARM AIR ADVECTION THAT
PRODUCED SHOWERY PRECIP IN THE EVENING THROUGH AROUND 2 AM IS EASING
UP THIS MORNING...BUT EXPECTED TO RAMP UP AGAIN EARLY THIS AFTERNOON
WITH A PASSING WEAK SHORTWAVE. THE NAM AND HRRR MODELS SHOW A LULL
IN PRECIP FOR ABOUT 3 HOURS MID MORNING...THEN ANOTHER ROUND OF
SHOWERY PRECIP THIS AFTERNOON.
THUS...EXTENDED THE FREEZING RAIN ADVISORY UNTIL 21Z FOR MOST OF MKX
FORECAST AREA. ONLY EXTENDED THE NORTHERN TIER OF COUNTIES UNTIL 18Z
SINCE DEEPER SATURATION SHOULD LEAD TO MORE SNOW THAN FREEZING
RAIN/DRIZZLE THERE. AGAIN...LAKESHORE AREAS WILL BE MARGINAL FOR THE
BELOW-FREEZING TEMPS TODAY TO MAINTAIN THE FREEZING RAIN
THREAT...BUT INLAND PORTIONS OF THE LAKE COUNTIES ARE EXPECTED TO
REMAIN BELOW FREEZING SO KEPT ALL COUNTIES IN THE ADVISORY.
LIGHT FREEZING DRIZZLE COULD PERSIST INTO THE EVENING...BUT DRYING
IS EXPECTED TO WORK INTO THE LOWER LEVELS AS THE SURFACE LOW SLIDES
EAST. WITH CLOUDS LINGERING OVER SOUTHERN WI...TEMPS WILL REMAIN
MODERATE...WITH LOWS DROPPING INTO THE UPPER TEENS TOWARD CENTRAL WI
AND THE UPPER 20S IN SOUTHEAST WI.
SATURDAY AND SUNDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
NOT MUCH HAS CHANGED WITH WEEKEND WINTER STORM...AS LATEST MODELS
STILL TAKE AIM AT SOUTHERN WISCONSIN. MAIN NOTICEABLE CHANGES ARE
AN OVERALL CONSENSUS INCREASE IN QPF AND VERY SLIGHT SHIFT
SOUTHWARD. THIS MINOR SHIFT RESULTED IN THE 00Z GUIDANCE
SUGGESTING SNOW FOR ALL OF THE FORECAST AREA...WITH THE MILDER AIR
ALOFT STAYING SOUTH.
OVERALL...LOOKS LIKE A PRETTY SOLID WINTER STORM IF THE CURRENT
DETAILS HOLD. CONSENSUS SFC LOW TRACK FROM WEST-CENTRAL INDIANA TO
SE MICHIGAN AND 700 MB LOW TRACK ACROSS SOUTHERN WISCONSIN ARE
USUALLY GOOD INDICATORS FOR A DECENT SNOWFALL. IN ADDITION...THOUGH
THE DENDRITE GROWTH ZONE IS NOT PARTICULARLY DEEP...FORCING WITHIN
THIS REGION REMAINS STRONG. WILL ALSO GET A BIT OF UPPER SUPPORT
AT THE ONSET OF THIS SYSTEM...AS THE FORECAST AREA WILL WITHIN THE
RIGHT ENTRANCE REGION OF A VERY STRONG UPPER JET. LATEST FORECAST
HAS THE HIGHEST AMOUNTS ACROSS THE SOUTHEAST TWO-THIRDS OF THE
FORECAST AREA...TAPERING OFF QUICKLY TOWARD THE FAR NW. THE SNOW
IS CURRENTLY EXPECTED TO MOVE IN DURING THE EVENING...WITH THE
HEAVIER SNOW ARRIVING BY MIDNIGHT AND PERSISTING INTO EARLY SUNDAY
MORNING.
WILL MAINTAIN THE WINTER STORM WATCH AS IS FOR NOW...AS THE STORM
IS A BIT TOO FAR OUT FOR A WARNING. ALSO...IT WOULD NOT TAKE MUCH
OF A SHIFT NORTH OR SOUTH IN THE STORM TRACK TO IMPACT CURRENT
EXPECTED AMOUNTS. THIS IS INCREASING CONFIDENCE WITH THIS SYSTEM
THOUGH...AS MODELS SEEM TO BE SETTLING ON A SOLUTION.
LIGHT SNOW MAY LINGER INTO SUNDAY NIGHT AS THE UPPER TROUGH
APPROACHES.
MONDAY THOUGH THURSDAY...FORECAST CONFIDENCE...LOW TO MEDIUM
LOOKS LIKE BELOW NORMAL TEMPS NEXT WEEK...WITH A CHANCE FOR LIGHT
SNOW AT TIMES AS SERIES OF SHORTWAVES PUSH THROUGH THE AREA. COULD
GET PRETTY CHILLY A COUPLE OF THE NIGHTS...WITH MODELS SUGGESTING
SUB-ZERO TEMPS. MAIN ISSUE WITH THIS PERIOD IS THAT MODELS ARE NOT
AGREEING VERY WELL ON THE TIMING OF THE WAVES AND EXTENT OF COLDER
TEMPS BEHIND THE WAVES. THUS KEPT POPS ON THE LOW END FOR NOW AND
DID NOT GO QUITE AS COLD AS SOME OF THE MODELS SUGGEST.
AVIATION/12Z TAFS/ AND MARINE...THESE SECTIONS WILL BE ADDED
SHORTLY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR
WIZ056>060-062>072.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ046-047-051-052-056>060-062>072.
FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR WIZ046-047-051-
052.
LM...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR LMZ643.
SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ643>646.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...MRC
SATURDAY THROUGH THURSDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
535 AM CST FRI DEC 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM CST FRI DEC 20 2013
FREEZING DRIZZLE/RAIN HAVE CAUSED SOME PROBLEMS FROM SLIGHTLY
NORTH OF I-90 IN WI...WEST TO JUST OUTSIDE OF ROCHESTER DOWNTOWN
AREA...THEN SOUTH. ACCIDENTS WERE PLENTIFUL...ROAD CREWS HAVE
BEEN OUT WORKING. THE CHALLENGE NOW IS WHAT WILL TODAY LOOK LIKE
AND WHAT TO DO WITH THE IMPACT AND ADVISORY.
GOES WATER VAPOR SHOWING SHORTWAVE TROUGH ENERGY ON A NW-SE AXIS
CENTERED NEAR ABOUT TOPEKA...RIDING NORTHEAST AT THE AREA.
PRESSURES HAVE BEEN RISING OVER THE FORECAST AREA AND COLD AIR
ADVECTION IS DECREASING TEMPERATURES /ABOUT 1F PER HOUR/ DESPITE
SOME PRECIPITATION. TO THE SOUTH ALONG THE FRONTAL BOUNDARY...FROM
THE QUAD CITIES TO SOUTH OF CHICAGO...SURFACE PRESSURES HAVE BEEN
WEAKLY FALLING WITH UPPER WAVE FORCING. SURFACE LOW CENTER IS
CLOSER TO WICHITA AT 08Z. WEAK 700-600MB-CENTERED FRONTOGENETIC
FORCING IS LOCATED ACROSS THE NORTHERN FORECAST ARE YIELDING THE
LINEAR SNOW BAND. THIS HAS SEEDED THE LOW-LEVEL 3-4KFT SUPERCOOLED
LIQUID LAYER /FINALLY/ TO CHANGE THE FZDZ/FZRA TO SNOW.
THE TREND TODAY IN THE RAP FRONTOGENESIS IS TO SHIFT
EASTWARD FROM ABOUT WHERE IT IS NOW...WITHOUT MUCH MORE SOUTHWARD
PROGRESSION...EXITING BY 15Z. 20.06Z NAM HAS VERY SIMILAR
GUIDANCE...HOWEVER THE BAND WOULD SHIFT A BIT FURTHER SOUTH. SINCE
THIS IS THE SEEDER CLOUD...IT DETERMINES THE NORTHERN EXTENT OF
THE FZRA/FZDZ AREA. TO THE SOUTH...ABOUT A 2KM DEEP SUPERCOOLED
LIQUID LAYER EXISTS. RADAR HAS SHOWN SOME DECREASE IN EITHER THE
DEPTH OR LIQUID DROP SIZE OVER THE PAST HOURS IN THE DRIZZLE LAYER
WITH LESS REFLECTIVITY. THIS MAKES FOR PAUSE ON THE ADVISORY. BUT ANOTHER
AREA OF FZRA SHOWERS ARE HEADING IN FROM ERN IOWA...WITH MORE INTO
NRN MO...SO NO SHORTAGE OF INSTABILITY SHOWERS HEADING THIS WAY.
WITH UPSTREAM ENERGY AND LIFT SHIFTING INTO THE AREA...FELT THE
NEED TO EXTEND /IN TIME/ THE FREEZING RAIN ADVISORY...SOUTH OF
THE SNOW BAND...WHERE MORE ICE CAN BE EXPECTED THIS MORNING. WHILE
THE LIFT IS NOTHING LIKE LAST EVENING...THE SURFACE LOW SHIFTING
TO THE SOUTH OF THE AREA WITH DEFORMATION IN THE LOW-LEVELS OVER
NERN IA AND SRN WI MEAN FZRA/FZDZ COULD CONTINUE. MODEL GUIDANCE
ALSO SUGGESTS A WEAK INVERTED TROUGH EMANATING NW FROM THE
SURFACE LOW TO ENHANCE LOW-LEVEL VERTICAL MOTION...ENHANCING CLOUD
DROP GROWTH FOR DRIZZLE. THE LATEST HRRR RUNS HAVE THIS
SUGGESTION...ESPECIALLY LATER ACROSS THE SOUTHERN COUNTIES. THE
SNOW BAND SHOULD ONLY MOVE ABOUT ONE MORE COUNTY SOUTH BEFORE
SHIFTING EAST...AND AGAIN ALLOWING FOR AN ALL LIQUID PRECIPITATION
TYPE. HOWEVER...BEING FURTHER NORTH...THE LIFT IS SOMEWHAT MORE
LIMITED AND THE THREAT ALSO MORE LIMITED /I-90 ROUGHLY/.
THEREFORE...THINK THERE IS ADDITIONAL THREAT FOR FREEZING
PRECIPITATION...ESPECIALLY ACROSS THE SOUTH...THROUGH THE DAY.
WILL EXTENDED THE FREEZING RAIN ADVISORY IN EXTREME NERN IA AND
SWRN WI UNTIL 3PM...AND AREAS NORTH UNTIL 18Z. WILL CANCEL THE
FREEZING RAIN ADVISORY IN AREAS IT IS NOW SNOWING. CONFIDENCE IS
LOW IN THAT NORTHERN AREA...IF THERE WILL BE ENOUGH VERTICAL
MOTION TO CAUSE FZDZ TODAY...BUT IF NEEDED IT CAN BE CANCELLED
EARLY. ICING LOOKS TO BE ABOUT ANOTHER 0.05 INCHES ACROSS THE
SOUTHERN AREA...BEFORE DIMINISHING LATER.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 405 AM CST FRI DEC 20 2013
SATURDAY SEEMS TO BE AN IN BETWEEN DAY BEFORE THE STRONG CYCLONE
OVER THE SWRN U.S. CURRENTLY...SHIFTS TOWARD THE GREAT LAKES.
CLOUD TO GROUND LIGHTNING STRIKES WERE SEEN OVERNIGHT IN AZ WHICH
IN THE WEST...USUALLY HAPPENS ONLY WITH THE STRONGEST IMPULSES. SO
THIS IS A NICE SHORTWAVE TROUGH. THERE ARE A NUMBER OF FAVORABLE
DYNAMICS WITH THIS SYSTEM THAT SHIFT IN...INCLUDING AN INTENSE
160KT+ JET THAT DEVELOPS OVER SRN CANADA AS THE RIDGE BUILDS
DOWNSTREAM OF THE SHORTWAVE EJECTING INTO THE PLAINS. THIS IS
CLASSIC FOR MIDWESTERN HEAVY SNOWFALL CLIMATOLOGY. THIS PLACES A
VERY FAVORABLE ENTRANCE REGION OVER IL/SRN WI SAT NIGHT AND
SUNDAY. A VERY WARM AND MOIST SECTOR /SPC MDT RISK/ WILL BE RIDING
NORTH OUT OF THE GULF ON 50-60KT LOW-LEVEL WINDS AS INFLOW TO THE
FORCING...WHICH IS STRONG QVECTOR CONVERGENCE ALOFT AS
EXPECTED...TO THE SOUTHEAST. THIS STORM WILL PRODUCE HEAVY
SNOWFALL...THE QUESTION IS LOCATION.
WHILE THE WPC WINTER WEATHER DESK CONFIDENCE IS LOWER...IT SEEMS
THE MODELS ARE DRAWING IN ON A SOLUTION THAT WOULD PLACE THE HEAVY
SNOW BAND JUST INTO GRANT COUNTY. THIS WAS VERY CLOSE TO THE
ONGOING FORECAST SO REALLY ONLY MINOR CHANGES WERE MADE. THE NAM
SOLUTIONS STILL SEEM OUT TO LUNCH COMPARED TO THE OTHER
DETERMINISTIC MODELS...A DRY AND EAST OUTLIER. OVERALL...WILL
KEEP THE WATCH UNTIL CONFIDENCE GROWS ON THE LOCATION...BUT THE
REGION WILL SEE A 7-10 INCH SNOW BAND FROM THIS SYSTEM.
WILL BE MONITORING FOR POSSIBLE CHRISTMAS DAY WEATHER ON THE WARM
AIR ADVECTION SHIFTING IN...AFTER THE MONDAY AND MONDAY NIGHT
COOL DOWN POST STORM. THE 20.00Z ECMWF IS A BIT MORE AGGRESSIVE ON
HOLIDAY WEATHER...WE WILL SEE.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 535 AM CST FRI DEC 20 2013
A BAND OF LIGHT SNOW HAS MOVED OVER THE KRST/KLSE TAF SITES WITHIN
THE LAST COUPLE OF HOURS. EXPECTING THIS SNOW TO TAPER OFF BY 15Z.
CONCERNED THAT THERE COULD STILL BE SOME VERY LIGHT FZDZ ONCE THE
SNOW BAND TAPERS OFF...MAINLY AT KLSE TIL NOON. PLAN ON LESS THAN
AN INCH OF SNOW ACCUMULATION. WILL HAVE TO WATCH POTENTIAL FOR
FREEZING DRIZZLE INTO THIS AFTERNOON DUE TO A VERY SATURATED BOUNDARY
LAYER WITH CONTINUED LIFT AS A LINGERING TROUGH OF LOW PRESSURE
REMAINS OVERHEAD. EXPECTING PRECIPITATION TO SHOVE OFF TO THE EAST
BY THIS EVENING AS HIGH PRESSURE BEGINS TO BUILD IN.
OTHERWISE...EXPECT MVFR CONDITIONS THROUGH THE PERIOD.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR WIZ041>044-053.
FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR WIZ054-
055-061.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ043-044-053>055-061.
MN...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR MNZ095-096.
IA...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR IAZ008>010-018-
019.
FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR IAZ011-
029-030.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR IAZ011-029-030.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...DAS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
405 AM CST FRI DEC 20 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 405 AM CST FRI DEC 20 2013
FREEZING DRIZZLE/RAIN HAVE CAUSED SOME PROBLEMS FROM SLIGHTLY
NORTH OF I-90 IN WI...WEST TO JUST OUTSIDE OF ROCHESTER DOWNTOWN
AREA...THEN SOUTH. ACCIDENTS WERE PLENTIFUL...ROAD CREWS HAVE
BEEN OUT WORKING. THE CHALLENGE NOW IS WHAT WILL TODAY LOOK LIKE
AND WHAT TO DO WITH THE IMPACT AND ADVISORY.
GOES WATER VAPOR SHOWING SHORTWAVE TROUGH ENERGY ON A NW-SE AXIS
CENTERED NEAR ABOUT TOPEKA...RIDING NORTHEAST AT THE AREA.
PRESSURES HAVE BEEN RISING OVER THE FORECAST AREA AND COLD AIR
ADVECTION IS DECREASING TEMPERATURES /ABOUT 1F PER HOUR/ DESPITE
SOME PRECIPITATION. TO THE SOUTH ALONG THE FRONTAL BOUNDARY...FROM
THE QUAD CITIES TO SOUTH OF CHICAGO...SURFACE PRESSURES HAVE BEEN
WEAKLY FALLING WITH UPPER WAVE FORCING. SURFACE LOW CENTER IS
CLOSER TO WICHITA AT 08Z. WEAK 700-600MB-CENTERED FRONTOGENETIC
FORCING IS LOCATED ACROSS THE NORTHERN FORECAST ARE YIELDING THE
LINEAR SNOW BAND. THIS HAS SEEDED THE LOW-LEVEL 3-4KFT SUPERCOOLED
LIQUID LAYER /FINALLY/ TO CHANGE THE FZDZ/FZRA TO SNOW.
THE TREND TODAY IN THE RAP FRONTOGENESIS IS TO SHIFT
EASTWARD FROM ABOUT WHERE IT IS NOW...WITHOUT MUCH MORE SOUTHWARD
PROGRESSION...EXITING BY 15Z. 20.06Z NAM HAS VERY SIMILAR
GUIDANCE...HOWEVER THE BAND WOULD SHIFT A BIT FURTHER SOUTH. SINCE
THIS IS THE SEEDER CLOUD...IT DETERMINES THE NORTHERN EXTENT OF
THE FZRA/FZDZ AREA. TO THE SOUTH...ABOUT A 2KM DEEP SUPERCOOLED
LIQUID LAYER EXISTS. RADAR HAS SHOWN SOME DECREASE IN EITHER THE
DEPTH OR LIQUID DROP SIZE OVER THE PAST HOURS IN THE DRIZZLE LAYER
WITH LESS REFLECTIVITY. THIS MAKES FOR PAUSE ON THE ADVISORY. BUT ANOTHER
AREA OF FZRA SHOWERS ARE HEADING IN FROM ERN IOWA...WITH MORE INTO
NRN MO...SO NO SHORTAGE OF INSTABILITY SHOWERS HEADING THIS WAY.
WITH UPSTREAM ENERGY AND LIFT SHIFTING INTO THE AREA...FELT THE
NEED TO EXTEND /IN TIME/ THE FREEZING RAIN ADVISORY...SOUTH OF
THE SNOW BAND...WHERE MORE ICE CAN BE EXPECTED THIS MORNING. WHILE
THE LIFT IS NOTHING LIKE LAST EVENING...THE SURFACE LOW SHIFTING
TO THE SOUTH OF THE AREA WITH DEFORMATION IN THE LOW-LEVELS OVER
NERN IA AND SRN WI MEAN FZRA/FZDZ COULD CONTINUE. MODEL GUIDANCE
ALSO SUGGESTS A WEAK INVERTED TROUGH EMANATING NW FROM THE
SURFACE LOW TO ENHANCE LOW-LEVEL VERTICAL MOTION...ENHANCING CLOUD
DROP GROWTH FOR DRIZZLE. THE LATEST HRRR RUNS HAVE THIS
SUGGESTION...ESPECIALLY LATER ACROSS THE SOUTHERN COUNTIES. THE
SNOW BAND SHOULD ONLY MOVE ABOUT ONE MORE COUNTY SOUTH BEFORE
SHIFTING EAST...AND AGAIN ALLOWING FOR AN ALL LIQUID PRECIPITATION
TYPE. HOWEVER...BEING FURTHER NORTH...THE LIFT IS SOMEWHAT MORE
LIMITED AND THE THREAT ALSO MORE LIMITED /I-90 ROUGHLY/.
THEREFORE...THINK THERE IS ADDITIONAL THREAT FOR FREEZING
PRECIPITATION...ESPECIALLY ACROSS THE SOUTH...THROUGH THE DAY.
WILL EXTENDED THE FREEZING RAIN ADVISORY IN EXTREME NERN IA AND
SWRN WI UNTIL 3PM...AND AREAS NORTH UNTIL 18Z. WILL CANCEL THE
FREEZING RAIN ADVISORY IN AREAS IT IS NOW SNOWING. CONFIDENCE IS
LOW IN THAT NORTHERN AREA...IF THERE WILL BE ENOUGH VERTICAL
MOTION TO CAUSE FZDZ TODAY...BUT IF NEEDED IT CAN BE CANCELLED
EARLY. ICING LOOKS TO BE ABOUT ANOTHER 0.05 INCHES ACROSS THE
SOUTHERN AREA...BEFORE DIMINISHING LATER.
.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 405 AM CST FRI DEC 20 2013
SATURDAY SEEMS TO BE AN IN BETWEEN DAY BEFORE THE STRONG CYCLONE
OVER THE SWRN U.S. CURRENTLY...SHIFTS TOWARD THE GREAT LAKES.
CLOUD TO GROUND LIGHTNING STRIKES WERE SEEN OVERNIGHT IN AZ WHICH
IN THE WEST...USUALLY HAPPENS ONLY WITH THE STRONGEST IMPULSES. SO
THIS IS A NICE SHORTWAVE TROUGH. THERE ARE A NUMBER OF FAVORABLE
DYNAMICS WITH THIS SYSTEM THAT SHIFT IN...INCLUDING AN INTENSE
160KT+ JET THAT DEVELOPS OVER SRN CANADA AS THE RIDGE BUILDS
DOWNSTREAM OF THE SHORTWAVE EJECTING INTO THE PLAINS. THIS IS
CLASSIC FOR MIDWESTERN HEAVY SNOWFALL CLIMATOLOGY. THIS PLACES A
VERY FAVORABLE ENTRANCE REGION OVER IL/SRN WI SAT NIGHT AND
SUNDAY. A VERY WARM AND MOIST SECTOR /SPC MDT RISK/ WILL BE RIDING
NORTH OUT OF THE GULF ON 50-60KT LOW-LEVEL WINDS AS INFLOW TO THE
FORCING...WHICH IS STRONG QVECTOR CONVERGENCE ALOFT AS
EXPECTED...TO THE SOUTHEAST. THIS STORM WILL PRODUCE HEAVY
SNOWFALL...THE QUESTION IS LOCATION.
WHILE THE WPC WINTER WEATHER DESK CONFIDENCE IS LOWER...IT SEEMS
THE MODELS ARE DRAWING IN ON A SOLUTION THAT WOULD PLACE THE HEAVY
SNOW BAND JUST INTO GRANT COUNTY. THIS WAS VERY CLOSE TO THE
ONGOING FORECAST SO REALLY ONLY MINOR CHANGES WERE MADE. THE NAM
SOLUTIONS STILL SEEM OUT TO LUNCH COMPARED TO THE OTHER
DETERMINISTIC MODELS...A DRY AND EAST OUTLIER. OVERALL...WILL
KEEP THE WATCH UNTIL CONFIDENCE GROWS ON THE LOCATION...BUT THE
REGION WILL SEE A 7-10 INCH SNOW BAND FROM THIS SYSTEM.
WILL BE MONITORING FOR POSSIBLE CHRISTMAS DAY WEATHER ON THE WARM
AIR ADVECTION SHIFTING IN...AFTER THE MONDAY AND MONDAY NIGHT
COOL DOWN POST STORM. THE 20.00Z ECMWF IS A BIT MORE AGGRESSIVE ON
HOLIDAY WEATHER...WE WILL SEE.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1137 PM CST THU DEC 19 2013
FREEZING RAIN AND DRIZZLE HAS SPREAD ACROSS THE REGION WITH
CONDITIONS DROPPING FROM MVFR TO IFR AS THE MAIN BAND OF DRIZZLE
MOVES IN. THIS WILL CREATE ICY CONDITIONS THROUGH MID TO LATE
MORNING ON FRIDAY. THIS FREEZING RAIN/DRIZZLE IS EXPECTED TO
CHANGE OVER TO LIGHT SNOW FOR A PERIOD ON FRIDAY BEFORE POSSIBLY
GOING BACK TO FREEZING DRIZZLE THROUGH THE REST OF THE DAY.
CONFIDENCE IS NOT HIGH ON WHETHER THAT SECOND CHANGE OVER WILL
OCCUR BACK TO DRIZZLE...BUT IT LOOKS POSSIBLE. CONDITIONS WILL
REMAIN MVFR TO IFR WITH WINDS SHIFTING FROM THE EAST TO NORTHEAST
IN THE AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 9 AM CST THIS MORNING FOR
WIZ032>034-041>044-053>055-061.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ043-044-053>055-061.
MN...FREEZING RAIN ADVISORY UNTIL 9 AM CST THIS MORNING FOR MNZ079-
086>088-094>096.
IA...FREEZING RAIN ADVISORY UNTIL 9 AM CST THIS MORNING FOR
IAZ008>011-018-019-029-030.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR IAZ011-029-030.
&&
$$
SHORT TERM...BAUMGARDT
LONG TERM...BAUMGARDT
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
351 AM CST FRI DEC 20 2013
.TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH
SURFACE LOW PRESSURE WILL SLOWLY MOVE ACROSS CENTRAL IL AND IN
TODAY. THE 850MB BAROCLINIC ZONE WILL REMAIN STATIONARY OVER
SOUTHERN WI...WITH THE SURFACE AND 925MB FRONT OVER NORTHERN IL.
SURFACE TEMPS WILL REMAIN BELOW FREEZING TODAY EXCEPT FOR RIGHT
ALONG THE SHORELINE.
A PERSISTENT DRY LAYER FROM 10-15 KFT IS EXPECTED TO HANG IN THERE
THROUGH THE DAY...POSSIBLY MOISTENING UP LATE THIS AFTERNOON. THIS
MEANS THAT SATURATED...SUB-FREEZING CONDITIONS FROM THE GROUND UP TO
AROUND 8KFT TODAY WILL CONTINUE TO PRODUCE LIGHT FREEZING
DRIZZLE. IF THE DEEPER SATURATION CAN OCCUR TO GET SOME SNOW
PRODUCTION...THEN SNOW COULD MIX IN WITH THE FREEZING DRIZZLE/RAIN
THIS AFTERNOON.
AS FOR FORCING...THE STRONGER 850-700MB WARM AIR ADVECTION THAT
PRODUCED SHOWERY PRECIP IN THE EVENING THROUGH AROUND 2 AM IS EASING
UP THIS MORNING...BUT EXPECTED TO RAMP UP AGAIN EARLY THIS AFTERNOON
WITH A PASSING WEAK SHORTWAVE. THE NAM AND HRRR MODELS SHOW A LULL
IN PRECIP FOR ABOUT 3 HOURS MID MORNING...THEN ANOTHER ROUND OF
SHOWERY PRECIP THIS AFTERNOON.
THUS...EXTENDED THE FREEZING RAIN ADVISORY UNTIL 21Z FOR MOST OF MKX
FORECAST AREA. ONLY EXTENDED THE NORTHERN TIER OF COUNTIES UNTIL 18Z
SINCE DEEPER SATURATION SHOULD LEAD TO MORE SNOW THAN FREEZING
RAIN/DRIZZLE THERE. AGAIN...LAKESHORE AREAS WILL BE MARGINAL FOR THE
BELOW-FREEZING TEMPS TODAY TO MAINTAIN THE FREEZING RAIN
THREAT...BUT INLAND PORTIONS OF THE LAKE COUNTIES ARE EXPECTED TO
REMAIN BELOW FREEZING SO KEPT ALL COUNTIES IN THE ADVISORY.
LIGHT FREEZING DRIZZLE COULD PERSIST INTO THE EVENING...BUT DRYING
IS EXPECTED TO WORK INTO THE LOWER LEVELS AS THE SURFACE LOW SLIDES
EAST. WITH CLOUDS LINGERING OVER SOUTHERN WI...TEMPS WILL REMAIN
MODERATE...WITH LOWS DROPPING INTO THE UPPER TEENS TOWARD CENTRAL WI
AND THE UPPER 20S IN SOUTHEAST WI.
.SATURDAY AND SUNDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH
NOT MUCH HAS CHANGED WITH WEEKEND WINTER STORM...AS LATEST MODELS
STILL TAKE AIM AT SOUTHERN WISCONSIN. MAIN NOTICEABLE CHANGES ARE
AN OVERALL CONSENSUS INCREASE IN QPF AND VERY SLIGHT SHIFT
SOUTHWARD. THIS MINOR SHIFT RESULTED IN THE 00Z GUIDANCE
SUGGESTING SNOW FOR ALL OF THE FORECAST AREA...WITH THE MILDER AIR
ALOFT STAYING SOUTH.
OVERALL...LOOKS LIKE A PRETTY SOLID WINTER STORM IF THE CURRENT
DETAILS HOLD. CONSENSUS SFC LOW TRACK FROM WEST-CENTRAL INDIANA TO
SE MICHIGAN AND 700 MB LOW TRACK ACROSS SOUTHERN WISCONSIN ARE
USUALLY GOOD INDICATORS FOR A DECENT SNOWFALL. IN ADDITION...THOUGH
THE DENDRITE GROWTH ZONE IS NOT PARTICULARLY DEEP...FORCING WITHIN
THIS REGION REMAINS STRONG. WILL ALSO GET A BIT OF UPPER SUPPORT
AT THE ONSET OF THIS SYSTEM...AS THE FORECAST AREA WILL WITHIN THE
RIGHT ENTRANCE REGION OF A VERY STRONG UPPER JET. LATEST FORECAST
HAS THE HIGHEST AMOUNTS ACROSS THE SOUTHEAST TWO-THIRDS OF THE
FORECAST AREA...TAPERING OFF QUICKLY TOWARD THE FAR NW. THE SNOW
IS CURRENTLY EXPECTED TO MOVE IN DURING THE EVENING...WITH THE
HEAVIER SNOW ARRIVING BY MIDNIGHT AND PERSISTING INTO EARLY SUNDAY
MORNING.
WILL MAINTAIN THE WINTER STORM WATCH AS IS FOR NOW...AS THE STORM
IS A BIT TOO FAR OUT FOR A WARNING. ALSO...IT WOULD NOT TAKE MUCH
OF A SHIFT NORTH OR SOUTH IN THE STORM TRACK TO IMPACT CURRENT
EXPECTED AMOUNTS. THIS IS INCREASING CONFIDENCE WITH THIS SYSTEM
THOUGH...AS MODELS SEEM TO BE SETTLING ON A SOLUTION.
LIGHT SNOW MAY LINGER INTO SUNDAY NIGHT AS THE UPPER TROUGH
APPROACHES.
.MONDAY THOUGH THURSDAY...FORECAST CONFIDENCE...LOW TO MEDIUM
LOOKS LIKE BELOW NORMAL TEMPS NEXT WEEK...WITH A CHANCE FOR LIGHT
SNOW AT TIMES AS SERIES OF SHORTWAVES PUSH THROUGH THE AREA. COULD
GET PRETTY CHILLY A COUPLE OF THE NIGHTS...WITH MODELS SUGGESTING
SUB-ZERO TEMPS. MAIN ISSUE WITH THIS PERIOD IS THAT MODELS ARE NOT
AGREEING VERY WELL ON THE TIMING OF THE WAVES AND EXTENT OF COLDER
TEMPS BEHIND THE WAVES. THUS KEPT POPS ON THE LOW END FOR NOW AND
DID NOT GO QUITE AS COLD AS SOME OF THE MODELS SUGGEST.
&&
.AVIATION/12Z TAFS/ AND MARINE...THESE SECTIONS WILL BE ADDED
SHORTLY.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR
WIZ056>060-062>072.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ046-047-051-052-056>060-062>072.
FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR WIZ046-047-051-
052.
LM...WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR LMZ643.
SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ643>646.
&&
$$
TODAY/TONIGHT AND AVIATION/MARINE...MRC
SATURDAY THROUGH THURSDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
324 AM CST FRI DEC 20 2013
.UPDATE...
ISSUED AT 323 AM CST FRI DEC 20 2013
PRELIMINARY CHANGES TO THE FREEZING RAIN ADVISORY BELOW. PLEASE
NOTE THE NORTHERNMOST COUNTIES MAY CHANGE OVER THE NEXT HOUR BASED
ON TRENDS.
UPDATE ISSUED AT 926 PM CST THU DEC 19 2013
RADAR/OBSERVATION TRENDS CONTINUE TO SHOW THE BAND OF FREEZING
DRIZZLE SURGING NORTHWARD ACROSS SOUTHEAST MINNESOTA AND WESTERN
WISCONSIN. WILL BE ADDING SOME COUNTIES TO THE FREEZING RAIN
ADVISORY...LIKELY THE REST OF THE FORECAST AREA EXCEPT
CLARK/TAYLOR COUNTIES WHERE ICE APPEARS TO BE IN FOR THE FULL
SATURATED COLUMN. ROADS HAVE ICED UP ACROSS SOUTHWEST WISCONSIN
AND NORTHEAST IOWA WHERE THE FREEZING DRIZZLE/RAIN HAS PERSISTED.
UPDATE COMING SHORTLY.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 307 PM CST THU DEC 19 2013
AS OF MID AFTERNOON THURSDAY...AREA OF LOW PRESSURE SITUATED IN
NORTHEAST KANSAS WITH WARM FRONT EXTENDING NORTHEAST INTO SOUTHERN
IOWA AND NORTHERN ILLINOIS. INCREASING ISENTROPIC LIFT LATER THIS
EVENING AND MOISTURE TRANSPORT OVERRUNNING THE WARM FRONT WILL
SATURATE THE LOW LEVELS...ESPECIALLY AFTER 00Z. FORECAST SOUNDINGS
STILL SHOW A COMPLICATED TOP DOWN PRECIPITATION TYPE SCENARIO WITH
BOTH A WARM NOSE AND A LOSS OF ICE IN THE UPPER LEVELS. FIRST...THE
PROBABILITY OF NO ICE PRESENT SHIFTED SLIGHTLY NORTH FROM
PREVIOUS FORECAST. 19.12Z NAM AND RAP NOW SHOW THIS EXTENDING NORTH
TO JUST SHY OF THE I-90 CORRIDOR IN WISCONSIN. IT IS NOT UNTIL VERY
EARLY FRIDAY MORNING THAT ICE GETS REINTRODUCED...AND A CHANGEOVER
TO LIGHT SNOW WOULD THEN OCCUR FOR PLACES SUCH AS VIROQUA OVER TO
JUNEAU/ADAMS COUNTIES. AT THE SAME TIME...RAP SOUNDINGS FOR DBQ
SHOW MAX WARM NOSE OF +4 DEGREES...AROUND +1 FOR BLR...AND THEN
BELOW ZERO FOR AREAS TO THE NORTH. SO...TIGHT GRADIENT FOR
FREEZING RAIN AND SNOW LINE. AS FAR AS ICE ACCUMULATIONS...UP TO
1/10 OF AN INCH STILL EXPECTED ON EXPOSED SURFACES...WHICH WILL
MAKE FOR SLICK TRAVEL OVERNIGHT INTO THE MORNING HOURS FRIDAY.
GIVEN THIS NORTHWARD JOG IN THE LOSS OF ICE / WARM NOSE...HAVE
EXPANDED THE FREEZING RAIN ADVISORY TO INCLUDE VERNON...JUNEAU AND
ADAMS COUNTIES IN WISCONSIN.
THE NORTHERN SIDE OF THIS WEATHER SYSTEM STILL EXPECTED TO PRODUCE A
BAND OF ACCUMULATING SNOW ALONG AND NORTH OF I-90...MAINLY AFTER
MIDNIGHT INTO FRIDAY MORNING. NO BIG CHANGES FROM
PREVIOUS FORECAST...WITH 1 TO 2 INCHES FOR MOST LOCATIONS AND
LOCALLY 3 INCH AMOUNTS POSSIBLE MAINLY FOR CENTRAL WISCONSIN. THIS
TOO COULD MAKE FOR SLICK ROADWAYS FOR THE FRIDAY MORNING
COMMUTE...AND CONSIDERED A HEADLINE FOR THIS BUT WILL HOLD OFF NOW
GIVEN COLLABORATION. IF LATER FORECASTS SHOW AN UPTICK IN
AMOUNTS...OR A DELAY MORE TOWARD THE MORNING COMMUTE...THEN AN
WINTER WEATHER ADVISORY MAY BE NEEDED FOR A FEW COUNTIES.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 307 PM CST THU DEC 19 2013
FOCUS OF THIS PERIOD IS SQUARELY ON THE WEEKEND AND THE POTENTIAL
FOR A WINTER STORM TO IMPACT PARTS OF THE FORECAST AREA. STILL
SOME DIFFERENCES BETWEEN THE MODELS BUT THE 19.12Z GFS AND ECMWF
ARE IN BETTER AGREEMENT WITH THE OVERALL PATTERN WITH THE 19.12Z
NAM APPEARING AT THIS TIME TO BE THE ODD MODEL OUT. THE UPPER
LEVEL LOW CURRENTLY ALONG THE CALIFORNIA COAST WILL MOVE OUT OF
THE DESERT SOUTHWEST AND TRACK NORTHEAST ACROSS THE CENTRAL
PORTION OF THE COUNTRY OVER THE WEEKEND. AS IT MOVES TOWARD THE
AREA...A NORTHERN STREAM SHORT WAVE WILL START TO MOVE TOWARD THE
UPPER MIDWEST FROM SOUTHWEST CANADA. THE DIFFERENCES IN THE MODEL
SOLUTIONS REVOLVE AROUND WHETHER THESE TWO SYSTEMS GET PHASED OR
WHETHER THEY STAY SEPARATE. THE NAM WOULD SUGGEST THEY GET PHASED
WHICH PUSHES THE SURFACE LOW AND ASSOCIATED QPF FARTHER SOUTHEAST.
THE GFS AND ECMWF DO NOT PHASE THE TWO SYSTEMS WHICH BRINGS THE
SURFACE LOW AND QPF BACK MORE TO THE NORTHWEST.
THE FORCING FROM THE SHORT WAVE TROUGH WILL START TO MOVE IN
SATURDAY NIGHT. MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB
LAYER SHOULD OCCUR LATE SATURDAY NIGHT JUST AHEAD OF THE WAVES
PASSAGE. MODERATE TO STRONG QG CONVERGENCE WILL BE PRODUCED BY THE
WAVE AND CENTERED OVER THE SOUTHEAST PART OF THE FORECAST AREA AT
12Z SUNDAY. WEAK TO MODERATE FRONTOGENESIS IS SHOWN BY THE GFS IN
THE 600-500 MB LAYER BETWEEN 06Z AND 18Z SUNDAY...ALSO OVER THE
SOUTHEAST PORTIONS OF THE FORECAST AREA. THERE MAY ALSO BE SOME
JET DYNAMICS THAT COME INTO PLAY AS WELL. THE GFS IS SUGGESTING A
SPLIT JET WITH THE AREA UNDER THE RIGHT ENTRANCE REGION OF THE
NORTHERN STREAM JET CORE TO ADD SOME AGEOSTROPHIC LIFT TO THE MIX.
THE GFS BUFKIT SOUNDING FOR BLUE RIVER SUGGEST THE DENDRITIC
GROWTH ZONE SHOULD BE ABOUT 100 MB DEEP WITH GOOD VERTICAL MOTIONS
THROUGH IT. THIS SHOULD LEAD TO SNOW RATIOS IN THE 14-16 TO 1
RANGE LEADING TO SNOW ACCUMULATIONS OF 4 TO 7 INCHES FROM ABOUT
FAYETTE COUNTY IOWA NORTHEAST INTO ADAMS/JUNEAU COUNTIES IN
CENTRAL WISCONSIN. THE POTENTIAL FOR THE HIGHER AMOUNTS IS THE
GREATEST IN PRIMARILY GRANT COUNTY WISCONSIN. THE NORTHWEST WINDS
WILL COME UP SUNDAY ON THE BACK SIDE OF THE SYSTEM WHICH WILL
LIKELY LEAD TO SOME DRIFTING SNOW AND POSSIBLY A LITTLE BLOWING
SNOW OVER THE MORE OPEN AREAS OF NORTHEAST IOWA. IN COORDINATION
WITH SURROUNDING OFFICES...WILL ISSUE A WINTER STORM WATCH FOR
SATURDAY NIGHT AND SUNDAY FOR THE ACCUMULATING SNOW AND ANY
POSSIBLE IMPACT ON THE BACK SIDE OF THE SYSTEM.
WITH THE FOCUS ON THE WEEKEND SYSTEM...HAVE NOT LOOKED EXTENSIVELY
AT THE FORECAST FOR NEXT WEEK. HAVE LET THE MODEL CONSENSUS GRIDS
RIDE WHICH GIVES A SMALL CHANCE FOR SOME SNOW TUESDAY AND TUESDAY
NIGHT ACROSS THE NORTH AS ANOTHER NORTHERN STREAM SHORT WAVE
TROUGH MOVES ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION. THE
COLDEST TEMPERATURES IN THE FORECAST LOOK TO BE BEHIND THE WEEKEND
SYSTEM WITH LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO SUNDAY
NIGHT...HIGHS ONLY IN THE SINGLE DIGITS ABOVE ZERO MONDAY WITH
SINGLE DIGITS BELOW ZERO FOR THE ENTIRE AREA MONDAY NIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1137 PM CST THU DEC 19 2013
FREEZING RAIN AND DRIZZLE HAS SPREAD ACROSS THE REGION WITH
CONDITIONS DROPPING FROM MVFR TO IFR AS THE MAIN BAND OF DRIZZLE
MOVES IN. THIS WILL CREATE ICY CONDITIONS THROUGH MID TO LATE
MORNING ON FRIDAY. THIS FREEZING RAIN/DRIZZLE IS EXPECTED TO
CHANGE OVER TO LIGHT SNOW FOR A PERIOD ON FRIDAY BEFORE POSSIBLY
GOING BACK TO FREEZING DRIZZLE THROUGH THE REST OF THE DAY.
CONFIDENCE IS NOT HIGH ON WHETHER THAT SECOND CHANGE OVER WILL
OCCUR BACK TO DRIZZLE...BUT IT LOOKS POSSIBLE. CONDITIONS WILL
REMAIN MVFR TO IFR WITH WINDS SHIFTING FROM THE EAST TO NORTHEAST
IN THE AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR WIZ041>044-053.
FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR WIZ054-
055-061.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ043-044-053>055-061.
MN...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR MNZ095-096.
IA...FREEZING RAIN ADVISORY UNTIL NOON CST TODAY FOR IAZ008>010-018-
019.
FREEZING RAIN ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR IAZ011-
029-030.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR IAZ011-029-030.
&&
$$
UPDATE...BAUMGARDT
SHORT TERM...ZT
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1137 PM CST THU DEC 19 2013
.UPDATE...
ISSUED AT 926 PM CST THU DEC 19 2013
RADAR/OBSERVATION TRENDS CONTINUE TO SHOW THE BAND OF FREEZING
DRIZZLE SURGING NORTHWARD ACROSS SOUTHEAST MINNESOTA AND WESTERN
WISCONSIN. WILL BE ADDING SOME COUNTIES TO THE FREEZING RAIN
ADVISORY...LIKELY THE REST OF THE FORECAST AREA EXCEPT
CLARK/TAYLOR COUNTIES WHERE ICE APPEARS TO BE IN FOR THE FULL
SATURATED COLUMN. ROADS HAVE ICED UP ACROSS SOUTHWEST WISCONSIN
AND NORTHEAST IOWA WHERE THE FREEZING DRIZZLE/RAIN HAS PERSISTED.
UPDATE COMING SHORTLY.
&&
.SHORT TERM...(THIS EVENING THROUGH FRIDAY)
ISSUED AT 307 PM CST THU DEC 19 2013
AS OF MID AFTERNOON THURSDAY...AREA OF LOW PRESSURE SITUATED IN
NORTHEAST KANSAS WITH WARM FRONT EXTENDING NORTHEAST INTO SOUTHERN
IOWA AND NORTHERN ILLINOIS. INCREASING ISENTROPIC LIFT LATER THIS
EVENING AND MOISTURE TRANSPORT OVERRUNNING THE WARM FRONT WILL
SATURATE THE LOW LEVELS...ESPECIALLY AFTER 00Z. FORECAST SOUNDINGS
STILL SHOW A COMPLICATED TOP DOWN PRECIPITATION TYPE SCENARIO WITH
BOTH A WARM NOSE AND A LOSS OF ICE IN THE UPPER LEVELS. FIRST...THE
PROBABILITY OF NO ICE PRESENT SHIFTED SLIGHTLY NORTH FROM
PREVIOUS FORECAST. 19.12Z NAM AND RAP NOW SHOW THIS EXTENDING NORTH
TO JUST SHY OF THE I-90 CORRIDOR IN WISCONSIN. IT IS NOT UNTIL VERY
EARLY FRIDAY MORNING THAT ICE GETS REINTRODUCED...AND A CHANGEOVER
TO LIGHT SNOW WOULD THEN OCCUR FOR PLACES SUCH AS VIROQUA OVER TO
JUNEAU/ADAMS COUNTIES. AT THE SAME TIME...RAP SOUNDINGS FOR DBQ
SHOW MAX WARM NOSE OF +4 DEGREES...AROUND +1 FOR BLR...AND THEN
BELOW ZERO FOR AREAS TO THE NORTH. SO...TIGHT GRADIENT FOR
FREEZING RAIN AND SNOW LINE. AS FAR AS ICE ACCUMULATIONS...UP TO
1/10 OF AN INCH STILL EXPECTED ON EXPOSED SURFACES...WHICH WILL
MAKE FOR SLICK TRAVEL OVERNIGHT INTO THE MORNING HOURS FRIDAY.
GIVEN THIS NORTHWARD JOG IN THE LOSS OF ICE / WARM NOSE...HAVE
EXPANDED THE FREEZING RAIN ADVISORY TO INCLUDE VERNON...JUNEAU AND
ADAMS COUNTIES IN WISCONSIN.
THE NORTHERN SIDE OF THIS WEATHER SYSTEM STILL EXPECTED TO PRODUCE A
BAND OF ACCUMULATING SNOW ALONG AND NORTH OF I-90...MAINLY AFTER
MIDNIGHT INTO FRIDAY MORNING. NO BIG CHANGES FROM
PREVIOUS FORECAST...WITH 1 TO 2 INCHES FOR MOST LOCATIONS AND
LOCALLY 3 INCH AMOUNTS POSSIBLE MAINLY FOR CENTRAL WISCONSIN. THIS
TOO COULD MAKE FOR SLICK ROADWAYS FOR THE FRIDAY MORNING
COMMUTE...AND CONSIDERED A HEADLINE FOR THIS BUT WILL HOLD OFF NOW
GIVEN COLLABORATION. IF LATER FORECASTS SHOW AN UPTICK IN
AMOUNTS...OR A DELAY MORE TOWARD THE MORNING COMMUTE...THEN AN
WINTER WEATHER ADVISORY MAY BE NEEDED FOR A FEW COUNTIES.
.LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY)
ISSUED AT 307 PM CST THU DEC 19 2013
FOCUS OF THIS PERIOD IS SQUARELY ON THE WEEKEND AND THE POTENTIAL
FOR A WINTER STORM TO IMPACT PARTS OF THE FORECAST AREA. STILL
SOME DIFFERENCES BETWEEN THE MODELS BUT THE 19.12Z GFS AND ECMWF
ARE IN BETTER AGREEMENT WITH THE OVERALL PATTERN WITH THE 19.12Z
NAM APPEARING AT THIS TIME TO BE THE ODD MODEL OUT. THE UPPER
LEVEL LOW CURRENTLY ALONG THE CALIFORNIA COAST WILL MOVE OUT OF
THE DESERT SOUTHWEST AND TRACK NORTHEAST ACROSS THE CENTRAL
PORTION OF THE COUNTRY OVER THE WEEKEND. AS IT MOVES TOWARD THE
AREA...A NORTHERN STREAM SHORT WAVE WILL START TO MOVE TOWARD THE
UPPER MIDWEST FROM SOUTHWEST CANADA. THE DIFFERENCES IN THE MODEL
SOLUTIONS REVOLVE AROUND WHETHER THESE TWO SYSTEMS GET PHASED OR
WHETHER THEY STAY SEPARATE. THE NAM WOULD SUGGEST THEY GET PHASED
WHICH PUSHES THE SURFACE LOW AND ASSOCIATED QPF FARTHER SOUTHEAST.
THE GFS AND ECMWF DO NOT PHASE THE TWO SYSTEMS WHICH BRINGS THE
SURFACE LOW AND QPF BACK MORE TO THE NORTHWEST.
THE FORCING FROM THE SHORT WAVE TROUGH WILL START TO MOVE IN
SATURDAY NIGHT. MODERATE TO STRONG PV ADVECTION IN THE 500-300 MB
LAYER SHOULD OCCUR LATE SATURDAY NIGHT JUST AHEAD OF THE WAVES
PASSAGE. MODERATE TO STRONG QG CONVERGENCE WILL BE PRODUCED BY THE
WAVE AND CENTERED OVER THE SOUTHEAST PART OF THE FORECAST AREA AT
12Z SUNDAY. WEAK TO MODERATE FRONTOGENESIS IS SHOWN BY THE GFS IN
THE 600-500 MB LAYER BETWEEN 06Z AND 18Z SUNDAY...ALSO OVER THE
SOUTHEAST PORTIONS OF THE FORECAST AREA. THERE MAY ALSO BE SOME
JET DYNAMICS THAT COME INTO PLAY AS WELL. THE GFS IS SUGGESTING A
SPLIT JET WITH THE AREA UNDER THE RIGHT ENTRANCE REGION OF THE
NORTHERN STREAM JET CORE TO ADD SOME AGEOSTROPHIC LIFT TO THE MIX.
THE GFS BUFKIT SOUNDING FOR BLUE RIVER SUGGEST THE DENDRITIC
GROWTH ZONE SHOULD BE ABOUT 100 MB DEEP WITH GOOD VERTICAL MOTIONS
THROUGH IT. THIS SHOULD LEAD TO SNOW RATIOS IN THE 14-16 TO 1
RANGE LEADING TO SNOW ACCUMULATIONS OF 4 TO 7 INCHES FROM ABOUT
FAYETTE COUNTY IOWA NORTHEAST INTO ADAMS/JUNEAU COUNTIES IN
CENTRAL WISCONSIN. THE POTENTIAL FOR THE HIGHER AMOUNTS IS THE
GREATEST IN PRIMARILY GRANT COUNTY WISCONSIN. THE NORTHWEST WINDS
WILL COME UP SUNDAY ON THE BACK SIDE OF THE SYSTEM WHICH WILL
LIKELY LEAD TO SOME DRIFTING SNOW AND POSSIBLY A LITTLE BLOWING
SNOW OVER THE MORE OPEN AREAS OF NORTHEAST IOWA. IN COORDINATION
WITH SURROUNDING OFFICES...WILL ISSUE A WINTER STORM WATCH FOR
SATURDAY NIGHT AND SUNDAY FOR THE ACCUMULATING SNOW AND ANY
POSSIBLE IMPACT ON THE BACK SIDE OF THE SYSTEM.
WITH THE FOCUS ON THE WEEKEND SYSTEM...HAVE NOT LOOKED EXTENSIVELY
AT THE FORECAST FOR NEXT WEEK. HAVE LET THE MODEL CONSENSUS GRIDS
RIDE WHICH GIVES A SMALL CHANCE FOR SOME SNOW TUESDAY AND TUESDAY
NIGHT ACROSS THE NORTH AS ANOTHER NORTHERN STREAM SHORT WAVE
TROUGH MOVES ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION. THE
COLDEST TEMPERATURES IN THE FORECAST LOOK TO BE BEHIND THE WEEKEND
SYSTEM WITH LOWS IN THE SINGLE DIGITS ABOVE AND BELOW ZERO SUNDAY
NIGHT...HIGHS ONLY IN THE SINGLE DIGITS ABOVE ZERO MONDAY WITH
SINGLE DIGITS BELOW ZERO FOR THE ENTIRE AREA MONDAY NIGHT.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 1137 PM CST THU DEC 19 2013
FREEZING RAIN AND DRIZZLE HAS SPREAD ACROSS THE REGION WITH
CONDITIONS DROPPING FROM MVFR TO IFR AS THE MAIN BAND OF DRIZZLE
MOVES IN. THIS WILL CREATE ICY CONDITIONS THROUGH MID TO LATE
MORNING ON FRIDAY. THIS FREEZING RAIN/DRIZZLE IS EXPECTED TO
CHANGE OVER TO LIGHT SNOW FOR A PERIOD ON FRIDAY BEFORE POSSIBLY
GOING BACK TO FREEZING DRIZZLE THROUGH THE REST OF THE DAY.
CONFIDENCE IS NOT HIGH ON WHETHER THAT SECOND CHANGE OVER WILL
OCCUR BACK TO DRIZZLE...BUT IT LOOKS POSSIBLE. CONDITIONS WILL
REMAIN MVFR TO IFR WITH WINDS SHIFTING FROM THE EAST TO NORTHEAST
IN THE AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...FREEZING RAIN ADVISORY UNTIL 9 AM CST FRIDAY FOR WIZ032>034-
041>044-053>055-061.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR WIZ043-044-053>055-061.
MN...FREEZING RAIN ADVISORY UNTIL 9 AM CST FRIDAY FOR MNZ079-086>088-
094>096.
IA...FREEZING RAIN ADVISORY UNTIL 9 AM CST FRIDAY FOR IAZ008>011-018-
019-029-030.
WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY
AFTERNOON FOR IAZ011-029-030.
&&
$$
UPDATE...HALBACH
SHORT TERM...ZT
LONG TERM...04
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1046 PM MST SAT DEC 21 2013
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 250 PM MST SAT DEC 21 2013
UPPER LOW IS LIFTING OUT INTO WESTERN OK WHILE TRAILING ENERGY IS
DROPPING ACROSS THE FORECAST AREA IN NW FLOW ALOFT. PRECIPITATION HAS
BEEN SLOW TO GET GOING ACROSS THE FORECAST AREA...THOUGH WEB CAMS
AND SURFACE OBS ALONG THE CONTDVD HAVE BEEN REPORTING SOME SNOW
THROUGH THE DAY. INITIALLY HEAVIEST SNOW AND BEST LIFT WILL BE OUT
ACROSS THE FAR SOUTHEAST CORNER OF THE FORECAST AREA WHERE WRAP
AROUND PRECIPITATION CONTINUES ACROSS BACA COUNTY. STILL SOME
VARIABILITY IN THE SHORT RANGE MODELS FOR SNOW AMOUNTS OUT THAT
WAY...BUT AN INCH OR TWO WOULDN`T BE OUT OF THE QUESTION ACROSS
SOUTHEAST PORTIONS OF BACA COUNTY. MEANWHILE...SHOULD START TO SEE
LIGHT SNOW RAMP UP ACROSS THE EASTERN MOUNTAINS AND ADJACENT PLAINS
BY 4 PM...WHICH WILL SPREAD SOUTH AND EAST THROUGH THE EVENING.
NAM12 AND HRRR SEEM TO BE BACKING OFF ON SNOWFALL AMOUNTS WITH EACH
RUN...WITH NAM12 NOW SHOWING AROUND 2-4 INCHES FOR THE SE MTS. HAVE
KEPT SNOW AMOUNTS IN THE 2-6 INCH RANGE AS SUSPECT THERE WILL BE POCKETS OF
HEAVIER AMOUNTS...HOWEVER WITHOUT A PERSISTENT DEEP NE UPSLOPE
FLOW...THINK THESE HEAVIER AMOUNTS WILL BE MORE LOCALIZED. THUS
ADVISORIES DO NOT SEEM WARRANTED AT THIS POINT. LIGHT SNOW WILL
WIND DOWN TOWARDS TOMORROW MORNING WITH PARTIAL CLEARING ACROSS
WESTERN AND NORTHERN PORTIONS OF THE AREA TOWARDS DAWN. THIS OPENS
UP THE POSSIBILITY FOR ANOTHER ROUND OF GROUND FOG AT KALS EARLY
SUNDAY MORNING...AND HAVE INTRODUCED THIS TO THE GRIDS.
QUIET WEATHER FOR SUNDAY...THOUGH NORTHWEST FLOW MAY KEEP SOME
SCATTERED OROGRAPHIC SNOW SHOWERS CONTINUING ACROSS THE CENTRAL MTS.
TEMPERATURES TOMORROW MAY END UP SIMILAR TO THOSE OF TODAY...PERHAPS
A LITTLE WARMER ACROSS PORTIONS OF THE PLAINS AND A TAD COOLER
ACROSS THE MTS WHERE H7 TEMPS WILL BE A LITTLE COOLER BEHIND THIS
EVENINGS SYSTEM. -KT
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 250 PM MST SAT DEC 21 2013
SUNDAY NIGHT-MONDAY...STRONG NORTH TO NORTHWEST FLOW ALOFT ACROSS
THE REGION SUNDAY NIGHT SLOWLY MODERATES THROUGH THE DAY MONDAY...AS
A BROAD UPPER TROUGH AND ASSOCIATED 120KT JET CORE ACROSS THE NORTHERN
ROCKIES TRANSLATES OUT ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS.
NORTHWEST FLOW ALOFT BEHIND THE SYSTEM LOOKS TO KEEP GENERALLY LIGHT
SNOWFALL IN PLACE ACROSS THE CENTRAL MTS THROUGH EARLY MONDAY
MORNING...WITH ACCUMULATIONS OF A FEW INCHES POSSIBLE ESPECIALLY
NORTH OF COTTONWOOD PASS. PASSING SYSTEM STAYS TOO FAR NORTH AND
EAST TO BRING PRECIPITATION TO THE REST OF SOUTH CENTRAL AND
SOUTHEAST COLORADO...THOUGH DOES SEND A WEAK COLD FRONT ACROSS
THE FAR EASTERN PLAINS EARLY MONDAY MORNING...KEEPING THE COOLEST
TEMPERATURES OUT NEAR THE KANSAS BORDER.
MONDAY NIGHT-CHRISTMAS DAY...LATEST MODELS CONTINUE TO DOWNPLAY
SNOWFALL ACROSS THE AREA FOR CHRISTMAS EVE AND EARLY CHRISTMAS DAY
WITH MODERATE NORTHWEST FLOW ALOFT ACROSS THE STATE AS ANOTHER
UPPER TROUGH TRANSLATES ACROSS THE NORTHERN ROCKIES. THE 12Z ECMWF
IS STILL A TAD DEEPER WITH SAID SYSTEM AND CONTINUES TO PRINT OUT
SOME QPF ACROSS THE EASTERN MTS TUESDAY NIGHT...THOUGH WITH ITS H7
FLOW PROGGED TO REMAIN NORTH TO NORTHWEST...ANY SNOW WOULD GENERALLY
REMAIN SOUTH OF HIGHWAY 50 ACROSS THE SOUTHERN I-25 CORRIDOR. AT ANY
RATE...MODEL CONSENSUS KEEPS SLIGHT POPS ACROSS THE HIGHER TERRAIN
AS WELL AS ALONG THE PALMER DVD AND RATON MESA FOR LATE TUESDAY
AFTERNOON THROUGH EARLY WEDNESDAY MORNING AND HAVE STAYED THE COURSE
FOR NOW. AS FOR TEMPS...WESTERLY FLOW AHEAD OF SAID SYSTEM LOOKS TO
KEEP BREEZY WINDS AND WARMING TEMPERATURES ACROSS THE STATE MONDAY
NIGHT AND TUESDAY...WITH ANOTHER WEAK COLD FRONT MOVING ACROSS THE
PLAINS CHRISTMAS EVE HELPING TO COOL HIGHS TO NEAR SEASONAL AVERAGES
FOR CHRISTMAS DAY.
WEDNESDAY NIGHT-SATURDAY...MODERATE NORTHWEST FLOW PROGGED ACROSS
THE REGION THROUGH THE REST OF THE EXTENDED PERIOD WITH A FEW MINOR
DISTURBANCES MOVING THROUGH THE FLOW ACROSS THE NORTHERN ROCKIES AND
INTO THE NORTHERN HIGH PLAINS. THIS WILL KEEP THE AREA GENERALLY
WARM AND DRY...SAVE A FEW OCCASIONAL FLURRIES ACROSS THE HIGHER
TERRAIN OF THE CENTRAL MTS...AS TEMPERATURES WARM BACK TO ABOVE
SEASONAL LEVELS THROUGH THE PERIOD.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1044 PM MST SAT DEC 21 2013
VFR CONDITIONS ARE EXPECTED AT KCOS AND KPUB TONIGHT AND SUNDAY.
KALS WL PROBABLY SEE SOME STRATUS AND FOG DEVELOP LATER TONIGHT
WITH IFR/LIFR CONDITIONS THRU ABOUT 16Z. OTHERWISE KALS WILL HAVE
VFR CONDITIONS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KT
LONG TERM...MW
AVIATION...28
AREA FORECAST DISCUSSION
NWS TAUNTON MA
445 AM EST SUN DEC 22 2013
.SYNOPSIS...
A FRONTAL BOUNDARY WILL GENERALLY BE TO THE NORTH OF THE REGION
THROUGH MONDAY. PERIODS OF RAIN SHOWERS AND UNSEASONABLY MILD
TEMPS ARE EXPECTED...ESPECIALLY TODAY INTO MONDAY FOR MUCH OF THE
AREA. SOUTHERN NEW HAMPSHIRE MAY EXPERIENCE SOME LIGHT FREEZING
RAIN LATE TODAY INTO TONIGHT. MAINLY DRY AND MUCH COLDER WEATHER
ARRIVES TUE AND WED.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
445 AM UPDATE...KEEPING A CLOSE EYE ON TEMPERATURES THIS MORNING
ACROSS SOUTHERN NH. 22/06Z NAM IS TOO WARM AT THE SURFACE AT
09Z...BUT IS NOT AS OVERLY WARM AS THE OTHER AVAILABEL GUIDANCE.
THE 22/07Z RAP ALSO SEEMS TO HAVE A BETTER HANDLE ON SURFACE
TEMPERATURES. BETWEEN THESE TWO SOURCES...EXPECTATIONS FOR SOME
ICING IN HILLSBOROUGH COUNTY HAVE INCREASED. IT IS POSSIBLE THIS
ICING COULD EXPAND WEST INTO CHESHIRE COUNTY...BUT IT IS SLIGHTLY
MORE LIKELY FOR THE COLDER AIR TO SURGE SOUTH INTO MIDDLESEX AND
ESSEX COUNTIES WHERE THE TERRAIN IS NOT AS MUCH OF AN IMPEDIMENT.
POSTED A FREEZING RAIN ADVISORY FOR HILLSBOROUGH COUNTY WHERE
CONFIDENCE IN SOME ICING IS HIGHEST. THE NEXT SHIFT MAY NEED TO
EXPAND THIS ADVISORY BASED ON THE PROGRESS OF THE COLD AIR.
LATEST NEAR-TERM GUIDANCE CONTINUES TO PRODUCE WIDESPREAD LOW
CLOUDS AND FOG ACROSS SOUTHERN NEW ENGLAND. JUST STARTING TO SE
SIGNS OF ITS DEVELOPMENT ACROSS THE CAPE AND ISLANDS...AS WELL AS
ACROSS PORTIONS OF THE CT RIVER VALLEY IN SOUTHWEST NH. STARTING
TO THINK THIS WILL BE A CASE WHERE THE STRATUS SORT OF DEVELOPS IN
PLACE RATHER THAN BEING ENTIRELY ADVECTED INTO OUR REGION.
STILL HAVING TROUBLE GETTING MEASURABLE RAINFALL WELL EAST OF THE
BERKSHIRES. RADAR MOSAICS CONTINUE TO DEPICT ECHOES DIMINISHING AS
THEY MOVE EAST. THIS IS LIKELY DUE TO DEEP...LINGERING DRY AIR
ACROSS SOUTHERN NEW ENGLAND...AS EVIDENCED IN THE 22/00Z CHH AND
OKX SOUNDINGS. DO NOT EXPECT THIS DRY AIR TO LAST ALL DAY...BUT
DID SLOW THE ARRIVAL OF WIDESPREAD MEASURABLE RAINFALL SOUTH OF
I-90. ONLY HAVE MODERATE CONFIDENCE IN THE TIMING...AND WILL
CONTINUE TO TWEAK THE TIMING OVER THE NEXT COUPLE OF HOURS.
LOCATION OF A FRONT WILL BE CRITICAL IN DETERMINING TODAY/S
FORECAST. BESIDES DETERMINING PRECIPITATION TYPE ACROSS SOUTHERN
NH...THIS FRONT WILL ALSO PROVIDE A FOCUS FOR MORE WIDESPREAD
PRECIPITATION. MODEL CONSENSUS IS THIS FRONT SHOULD DROP INTO
NORTHERN MA LATER TODAY. THIS MEANS THERE WILL BE A LARGE
TEMPERATURE GRADIENT SOMEWHERE IN SOUTHERN NEW ENGLAND. COULD BE
AS MUCH AS A 20 DEGREE DIFFERENCE IN FORECAST TEMPERATURES
DEPENDING ON WHICH SIDE OF THIS FRONT AN AREA HAPPENS TO BE. MORE
THOUGHT WILL NEED TO BE GIVEN TO TEMPERATURES LATER TODAY.
IF TEMPERATURES DROP BELOW FREEZING...IT WILL NOT BE UNTIL LATE
AFTERNOON...EVEN LOOKING AT THE COLDER NAM SOLUTION. WILL LIKELY
NEED TO CONSIDER A FREEZING RAIN ADVISORY SOMEWHERE ACROSS
NORTHERN MA INTO SOUTHERN NH LATE TODAY INTO TONIGHT. NEED TO
FIGURE OUT THE PROGRESS OF THIS FRONT FIRST THOUGH.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
RAIN AND/OR FREEZING RAIN WILL CONTINUE THROUGH TONIGHT. IN
ADDITION...DENSE FOG WILL REMAIN A CONCERN...PARTICULARLY ON THE
WARM SIDE OF THE FRONT. THE TIGHT TEMPERATURE GRADIENT WILL
CONTINUE WITH THE COLDEST TEMPERATURES ACROSS SOUTHEASTERN NEW
HAMPSHIRE AND NORTHEASTERN MASSACHUSETTS. A MILD NIGHT FOR THE
REST OF THE AREA.
EXPECTING ANOTHER LOW PRESSURE TO MOVE ALONG A FRONTAL BOUNDARY
ACROSS SOUTHERN NEW ENGLAND MONDAY. MOISTURE IS RATHER HIGH FOR
THIS TIME OF YEAR...WITH PRECIPITABLE WATER VALUES BETWEEN
1.00-1.75 INCHES. THUS...COULD SEE LOCALLY HEAVY RAINFALL TONIGHT
INTO MONDAY. THE GREATEST RISK WOULD BE TOWARD THE SOUTH COAST.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
HIGHLIGHTS...
*MAINLY DRY BUT MUCH COLDER CHRISTMAS EVE AND DAY
* DRY HIGH PRESSURE FOR THE REMAINDER OF THE WEEK
OVERVIEW AND MODEL PREFERENCES...
22/00Z MODEL GUIDANCE SUITE WITH THIS UPDATE IS SHOWING GENERALLY
GOOD AGREEMENT THROUGH MUCH OF THE COMING WEEK. THE SOMEWHAT
AMPLIFIED RIDGE-TROF-RIDGE SETUP ACROSS MUCH OF THE NORTHEASTERN
CONUS ARE FAIRLY WELL AGREED UPON AT THE SYNOPTIC SCALE. GIVEN
THIS...FEEL THAT A GENERAL CONSENUS OF DETERMINISTIC AND ENSEMBLE
GUIDANCE ALONG WITH THE PREVIOUS FORECAST WILL WORK AS A GOOD
BASELINE FOR THIS LONG-TERM FORECAST UPDATE.
IN TERMS OF THE SYNOPTIC SETUP...THROUGH MID WEEK A LONGWAVE TROF
WILL BE SETTLING OVER NEW ENGLAND AS STRONG RIDGING CONTINUES IN
THE ATLANTIC BUT SLIDES A BIT FURTHER E. THIS TROF WILL CARRY WITH
IT SOME COLDER TEMPERATURES FOR MID WEEK WHICH WILL WARM A
SECONDARY AND WEAKER RIDGE /AND ASSOCIATED 1040 HIGH PRES/ MOVES
OVER. THE DRY CONDITIONS LOOK TO PREVAIL WITH YET ANOTHER TROF BY
LATE IN THE WEEK AS IT IS EXPECTED TO WEAKEN AND OPEN AS IT
INTERACTS WITH THE STRONG RIDGING OFFSHORE. THERFORE...WITH THIS
UDPATE...IT APPEARS MUCH OF THE LONG TERM PERIOD WILL BE DRY AS
THE GENERAL FLOW PATTERN KEEPS SUBTROPICAL MOISTURE AT BAY.
DETAILS...
MON NIGHT...
FRONTAL WAVE OF LOW PRES WILL BE MOVING FURTHER OFFSHORE DURING
THE OVERNIGHT HOURS. PRECIP SHIELS ACROSS THE SOUTHEASTERN THIRD
OF THE BOX CWA WILL ALSO GRADUALLY SHIFT OFFSHORE WITH TIME SUCH
THAT IT WILL LIKELY BE CLEAR OF THE EVEN THE CAPE AND ISLANDS BY
12Z. AT THIS POINT...EXAMINING BUFKIT PROFILES SUGGESTS MUCH OF
THE REMNANT PRECIP IS RAIN...BUT A BRIEF CHANGEOVER TO SNOW IS
POSSIBLE DURING THE EARLY MORNING HOURS. AS COLD ADVECTION
INCREASES AHEAD OF HIGH PRES AND A MUCH COLDER AIRMASS. ANY ACCUMS
WOULD BE LIGHT TO NONE.
TUE INTO WED...
AS TROF SETTLES ACROSS THE REGION THE NOSE OF 1040 HPA HIGH PRES
AND A MUCH COLDER AIRMASS WILL SETTLE ACROSS THE REGION. H85 TEMPS
AVERAGE AROUND -12C DURING THE DAY TUE THEN SLIDE DOWN AS LOW AS
-20C BY EARLY WED. CONDITIONS ARE EXPECTED TO BE MORE BLUSTERY ON
TUE WITH DECENT PRES GRADIENT APPARENT...YIELDING 20+ MPH NW
FLOW...BUT AMBIENT TEMPERATURES ARE COOLER ON WED. AVERAGE TEMPS
ARE LIKELY TO BE 10-15 DEGREES /F/ BELOW NORMAL FOR LATE DEC. DRY
WEATHER PREVAILS OTHERWISE UNDER STRONG SUBSIDENCE WITH 1040 HIGH
PRES.
THU AND FRI...
SECONDARY SHORTWAVE WILL WEAKEN AND OPEN AS IT APPROAHCES THE
NORTHEAST US/CANADA. ATTENDANT CLIPPER LOW PRES IS EXPECTED TO
MOVE ACROSS NRN NEW ENGLAND AND SRN QUEBEC. THIS IS LIKELY TO KEEP
SRN NEW ENGLAND ON THE CLIMATOLOGICALLY DRY SIDE OF THIS CLIPPER.
NOT OUT OF THE QUESTION A FEW FLURRIES ARE SEEN WITH THE ACTUAL
COLD FRONT LATE THU...BUT ITS LIKELY ONLY CLOUD COVER IS OBSERVED.
THE ONLY CAVEAT WILL BE AN OFFSHORE WAVE WHICH MAY RIDE THE FRONT
JUST AS IT MOVES OFFSHORE...WILL NEED TO KEEP AN EYE ON THIS BUT
AT THIS POINT IT APPEARS THE WAVE PHASING IS FAR TOO LATE TO
AFFECT SRN NEW ENGLAND. AFTER A SLIGHT MODERATE WITH TEMPERATURES
CLOSER TO NORMAL ON THU...THE COLD FRONT ASSOCIATED CLIPPER WILL
BRING ANOTHER ROUND OF BLUSTERY AND COOLER WX FOR THE DAY FRI.
NEXT WEEKEND...
STILL A LOT OF UNCERTAINTY /AS IS TYPICAL/ FROM DAY 6 ONWARD.
EARLY INDICATION IS THAT HIGH PRES MAY ONCE AGAIN SETTLE ACROSS
THE REGION BEHIND THE CLIPPER AND PHASING WAVES OFFSHORE...BUT
THIS WOULD BE DEPENDENT ON THE FINAL FLOW PATTERN ONCE THE PHASING
DOES/DOES NOT OCCUR. FOR NOW...WILL ERR ON THE SUGGESTED DRIER
SOLUTION.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
NEAR TERM /THROUGH MONDAY/...
430 AM UPDATE...
IFR BECOMING MORE WIDESPREAD ACROSS SOUTHERN NEW ENGLAND THIS
MORNING. HAVE HIGH CONFIDENCE CONDITIONS WILL LOWER THROUGH
TODAY...BUT LOW CONFIDENCE ON THE PRECISE TIMING. LLWS EXPECTED
THROUGH THIS MORNING ACROSS SOUTHEAST MA WITH STRONG WSW JET JUST
ABOVE THE SURFACE. MODERATE PROBABILITY OF FREEZING RAIN ACROSS
PORTIONS OF SOUTHERN NH AND POSSIBLY NORTHEAST MA LATE TODAY.
AIRPORT WEATHER WARNING HAS BEEN ISSUED FOR KMHT.
TONIGHT...MODERATE CONFIDENCE. MVFR/IFR CONDITIONS CONTINUE IN
FOG AND -SHRA. SOME IMPROVEMENT FROM NORTHWEST TO SOUTHEAST AS A
FRONT MOVES THROUGH SOUTHERN NEW ENGLAND.
MONDAY...MODERATE CONFIDENCE. PERIODS OF IFR POSSIBLE IN RAIN...
POSSIBLY HEAVY AT TIMES. AREAS OF FOG.
KBOS TAF...HIGH CONFIDENCE IN TRENDS. LOW CONFIDENCE IN TIMING.
KBDL TAF...HIGH CONFIDENCE IN TRENDS. LOW CONFIDENCE IN TIMING.
OUTLOOK...MONDAY NIGHT THROUGH THURSDAY...
MON NIGHT...HIGH CONFIDENCE.
IMPROVING TO MVFR/VFR AS PRECIP ENDS NW TO SE.
TUE AND WED...HIGH CONFIDENCE.
VFR. SOME NW WINDS 25-30 KT AT TIMES TUE.
THURSDAY...HIGH CONFIDENCE.
VFR.
&&
.MARINE...
FORECASTER CONFIDENCE LEVELS...
LOW...LESS THAN 30 PERCENT.
MODERATE...30 TO 60 PERCENT.
HIGH...GREATER THAN 60 PERCENT.
PERSISTENT SOUTHWEST WINDS AS A FRONTAL BOUNDARY REMAINS DRAPED
ACROSS CENTRAL AND NORTHERN NEW ENGLAND WITH WAVES OF LOW PRESSURE
TRACKING ALONG THIS FRONT. SOUTHWEST WINDS DIMINISH MONDAY AS A
FRONT AND AREA OF LOW PRES MOVE SOUTH INTO THE REGION. PERIODS OF
HEAVY RAIN WILL LIKELY REDUCE VISIBILITY MONDAY. MODERATE TO HIGH
CONFIDENCE THRU MONDAY.
OUTLOOK...MON NIGHT THROUGH THU...
MON NIGHT INTO TUE NIGHT...HIGH CONFIDENCE.
SEAS WILL CONTINUE TO DECLINE ACROSS THE REGION ESPECIALLY AS
WINDS SHIFT TO THE NW LATE MON NIGHT. HOWEVER...WITH THIS NW WIND
SHIFT...WIND GUSTS OF 25-30 MPH ARE EXPECTED ACROSS ALL WATERS.
SMALL CRAFT ADVISORIES ARE LIKELY TO CONTINUE.
WED AND WED NIGHT...HIGH CONFIDENCE.
IT APPEARS SEAS WILL SLACKEN ENOUGH AS WINDS RECEDE EARLY WED THAT
A PERIOD OF MAINLY QUIET BOATING WEATHER IS EXPECTED UNDER HIGH
PRES.
THU...MODERATE CONFIDENCE.
WINDS AND SEAS MAY BEGIN TO BUILDS FROM THE S AHEAD OF A COLD
FRONT DURING THE DAY THU. IT IS POSSIBLE THAT SMALL CRAFT ADVISORY
CONDITIONS ARE REACHED...OVER THE SRN WATERS FIRST.
&&
.CLIMATE...
RECORD HIGHS FOR DECEMBER 22ND...
HARTFORD /BDL/ 59 DEGREES...1990
WORCESTER /ORH/ 63 DEGREES...1923
BOSTON /BOS/ 62 DEGREES...1990
PROVIDENCE /PVD/ 61 DEGREES...1990
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...FREEZING RAIN ADVISORY FROM NOON TODAY TO MIDNIGHT EST TONIGHT
FOR NHZ012-015.
RI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR ANZ235-237-250.
SMALL CRAFT ADVISORY UNTIL 6 AM EST TUESDAY FOR ANZ254>256.
&&
$$
SYNOPSIS...BELK/DOODY
NEAR TERM...BELK
SHORT TERM...BELK
LONG TERM...DOODY
AVIATION...BELK/DOODY
MARINE...BELK/DOODY
CLIMATE...STAFF
AREA FORECAST DISCUSSION
NWS ALBANY NY
403 AM EST SUN DEC 22 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT FROM CENTRAL NEW YORK TO THE MAINE COAST
WILL SHIFT SLIGHTLY AS A STORM MOVES ALONG IT TODAY. NORTH OF IT
IT WILL BE CHILLY WITH RAIN AND FREEZING RAIN...WITH RAIN AND VERY
MILD WEATHER TO ITS SOUTH. THE STORM WILL DRAG A COLD FRONT
THROUGH THE REGION TONIGHT AND THEN SLIDE SLOWLY OFFSHORE MONDAY.
HIGH PRESSURE WILL BUILD FROM ONTARIO INTO NEW YORK TUESDAY INTO
CHRISTMAS...WITH MUCH COLD AIR FILTERING INTO THE REGION. THE
WEEK WILL END WITH A SERIES OF FAST MOVING WEATHER SYSTEMS WITH
BOUTS OF SNOW SHOWERS AND GENERALLY SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 321 AM EST...WIDE VARIETY OF TEMPERATURES ACROSS THE REGION
EARLY THIS MORNING WITH STALLED FRONTAL BOUNDARY SITUATED DIRECTLY
ACROSS THE CENTRAL PORTION OF THE CWA. NORTH OF THE
BOUNDARY...VERY COLD CANADIAN AIR IS PULLED SOUTHWARD THANKS TO A
LOW LEVEL NNE FLOW THROUGH THE CHAMPLAIN VALLEY AND INTO THE UPPER
HUDSON VALLEY REGION. THIS HAS ALLOWED TEMPS TO DROP BELOW
FREEZING FOR THE GLENS FALLS AND SARATOGA SPRINGS AREA. TEMPS HAVE
FALLEN INTO THE MID 30S IN THE CAPITAL REGION.
AT THE SAME TIME...VERY WARM TEMPS ALOFT ARE IN PLACE THANKS TO A
STRONG SOUTHERLY FLOW ALOFT. 850 HPA TEMPS HAVE RISEN TO +7 TO +15
DEGREES C ACROSS OUR REGION. AS A RESULT...THE WARMER TEMPS AT THIS
HOUR ARE ACROSS THE MOUNTAIN PEAKS OF THE CATSKILLS...SRN GREENS AND
BERKSHIRES...WHERE TEMPS ARE WELL INTO THE 50S.
WITH AN APPROACHING LOW PRESSURE AREA AND THE SFC BOUNDARY IN
PLACE...OVERRUNNING PRECIP...MAINLY IN THE FORM OF RAIN...IS MOVING
ACROSS THE WESTERN ADIRONDACKS. SOME LIGHTER RAIN AND FREEZING RAIN
IS OCCURRING FURTHER EAST ACROSS THE LAKE GEORGE/SARATOGA REGION AND
SOME LIGHT RAIN SHOWERS ARE OVER WESTERN NEW ENGLAND. THERE IS A
BREAK IN THE PRECIP OVER THE REMAINDER OF THE AREA...AS A DRY SLOT
IS ATTEMPTING TO MOVE INTO THE AREA WITH LITTLE PRECIP SHOWN ON
UPSTREAM RADARS. THE LATEST 03Z 3KM HRRR SHOWS THIS DRY SLOT SHOULD
START TO FILL IN TOWARDS DAYBREAK AS THE LOW PRESSURE AREA MOVES
NORTHEAST ACROSS THE OHIO VALLEY AND EVENTUALLY TOWARDS UPSTATE
NY...SO WE WILL CONTINUE RATHER HIGH POPS BY AROUND DAYBREAK DESPITE
THE CURRENT LULL IN THE PRECIP AS SHOWN ON RADAR. FOR NOW...IT
DOESN/T APPEAR THAT THE CAPITAL REGION WILL BE SEEING ANY FREEZING
RAIN...AS THE APPROACHING STORM SHOULD ALLOW THE STALLED BOUNDARY TO
START TO MOVE NORTHWARD AS A WARM FRONT...AND BRING THE ALBANY AREA
INTO THE WARM SECTOR ONCE THE NEXT ROUND OF RAINFALL BEGINS.
FURTHER NORTH...IT MAY TAKE UNTIL THE MID TO LATE MORNING FOR THE
WARM FRONT TO MOVE THROUGH AND TEMPS TO WARM UP. AS A RESULT...A
PROLONGED PERIOD OF FREEZING RAIN CAN BE EXPECTED ACROSS THE LAKE
GEORGE SARATOGA REGION. ICE ACCRETION AMOUNTS WILL RANGE FROM A
TRACE TO A TENTH ACROSS THE SARATOGA SPRINGS AREA TO A FEW TENTHS
FOR GLENS FALLS TO ABOUT FOUR TENTHS ACROSS THE NORTH END OF LAKE
GEORGE. ASIDE FROM SOME HAZARDOUS DRIVING CONDITIONS...THIS MAY LEAD
TO SOME ISOLATED POWER OUTAGES.
AREAS IN THE WARM SECTOR SHOULD SEE SFC TEMPS WARM
SIGNIFICANTLY...AS THOSE WARMER TEMPS ALOFT ARE MIXED IN THE
BOUNDARY LAYER. MAX TEMPS LOOK TO REACH INTO THE 50S ACROSS MUCH OF
THE CENTRAL AND SOUTHERN PARTS OF THE AREA...WITH SOME LOW TO MID
60S FOR THE MID HUDSON VALLEY.
WHILE IT WILL RAIN THROUGH THE MORNING HOURS...MOST AREAS WILL BE
DONE SEEING PRECIPITATION BY THE EARLY TO MID AFTN HOURS...AS THE
STORM/S COLD FRONT PASSES THROUGH THE AREA. TOTAL RAINFALL FOR
SUNDAY WILL RANGE FROM JUST A QUARTER OF AN INCH ACROSS LITCHFIELD
COUNTY CT...TO AROUND THREE QUARTERS OF AN INCH IN THE CAPITAL
REGION TO ABOUT AN INCH AND A HALF OVER THE ADIRONDACKS. SEE THE
HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL TO AFFECT AREA RIVERS
AND STREAMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
FOR THIS PERIOD THE MODEL SUITE (GEM/GFS/ECMWF) ARE IN FAIRLY
GOOD AGREEMENT. DURING THE THIS EVENING THE SFC LOW AND ITS UPPER
DYNAMICS WILL LIFT NE OUT OF FCA. A SERIES OF 500HPA SHORT WAVES
WILL DIG A TROF OVER GRTLKS...MAINTAINING A STRONG SW 500HPA FLOW
OVER THE EASTERN THIRD OF THE NATION. FOR A TIME THIS WILL ACT TO
WEAKEN THE SFC LOW FURTHER OVER NEW ENG...BUT THE SFC LOW WILL
DRAG A CDFNT THROUGH THE REGION TNGT. GIVEN THE UPPER FLOW COOLER
AIR WILL BE SLOW TO FILTER IN OVERNIGHT....AND TEMPS WILL REMAIN
ABV FREEZING IN MOST AREAS...WITH SNOW MELT CONTINUING.
BY MONDAY THIS CDFNT WILL NEARLY STALL ALONG THE EASTERN
SEABOARD...AND WITH DIGGING 500HPA TROF INTERACTING WITH THE
COASTAL BAROCLINIC ZONE WILL TRIGGER A BOUT OF OVERRUNINNG RAIN...ALONG
THE I-95 CORRIDOR THAT WILL BACK BUILD INTO SE PORTIONS OF FCA.
QPF DURING MONDAY WITH THIS SHOULD BE 0.25 TO 0.50 IN THESE
AREAS...AND GIVEN THESE AREAS WERE IN THE WARM SECTOR MUCH OF THE
CURRENT EVENT...THEY MELTED MOST OF THEIR SNOW...BUT HAD LITTLE
RAINFALL. ADD TO THAT THE 2-3 DAYS THIS OCCURRED...THE ADDITIONAL
RAIN IN SOUTHEAST AREAS MONDAY SHOULD NOT RESULT IN ANYTHING OTHER
THAN WITHIN BANK RISES.
FURTHER WEST MONDAY AS HIGH PRESSURE BUILDS EAST WIND GRADIENT
WILL INCR AND AS THE 500HPA TROF PUSHES EAST A MUCH STRONGER 2NDRY
CDFNT WILL PUSH INTO THE REGION LATE MONDAY AND THROUGH MONDAY
NIGHT. TEMPS MONDAY WILL HOLDS STEADY THEN FALL DURING THE AFTN.
MONDAY NIGHT INTO TUES THE PASSAGE OF THE 500HPA TROF...CAA WILL
RESULT IN SCT -SHSN ACTIVITY. HWVR LLVL FLOW WILL BE TOTALLY
UNFAVORABLE FOR LK EFFECT OVER EASTERN NY.
ONCE THE 500HPA TROF EXITS CHRISTMAS EVE BOTH A 500HPA RIDGE...AND
SFC HIGH PRESSURE WILL SETTLE OVER NYS AND MID ATLC REGION. THIS
WILL SET THE STAGE FOR A FRIGID NIGHT WITH IDEAL RADIATIONAL
COOLING...ONE OF THE LONGEST NIGHTS OF THE YEAR...CLEAR SKIES AND
DRY AIR MASS. LOWS WILL PLUNGE TO -20F IN PARTS OF THE ADIRONDACKS
TO AROUND 10 IN THE SE.
TEMPS WILL RECOVER CHRISTMAS DAY TO THE TEENS AND 20S AS SFC HIGH
SLIDES OFFSHORE. SOME CLOUDS MAY ARRIVE IN THE AFTERNOON AS NEXT
WEAK SYSTEM APPROACHES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE EFP WILL FEATURE A SERIES OF FAST MOVING SYSTEMS IN W-NW FLOW.
MOST WILL BE FAIRLY WK CDFNTS AND/OR 500HPA SHORT WVS...WHICH
WILL INCR CLOUDS AND PRODUCE SCT -SHSN AND AT TIMES HAVE SOME
INTERACTION WITH THE GRTLKS. TEMPS WILL RETURN TO NEAR NORMALS
AFTER A FRIGID CHRISTMAS. TYPICAL WINTER IN UPSTATE NY.
CHRISTMAS NIGHT AND THURS THE FIRST OF THESE SYSTEMS RACES ACROSS
ONTARIO...WITH A FEW WEAK FRONTS AND A 500HPA SHORT WV. MAIN
IMPACTS WILL INCR CLOUDS MAINLY N & W. THU NT IT WILL DRAG A
CDFNT THROUGH WITH SOME -SHSN ACTIVITY MAINLY N & WEST. IN ITS
WAKE FRI CAA AND A 2NDARY CDFNT AND NW FLOW WILL TRIGGER SCT -SHSN
WITH SOME LK ASSISTANCE. WK SFC HIGH BUILDS OVER FCA FRI NT.
SAT ANOTHER WK SHORT WV AND SFC SYSTEM MOVES THROUGH THE GRTLKS
WITH A LITTLE WAA INCRG CLOUDS AND SCT -SHSN IN ECMWF...GETTING SOME
ASSIST FM THE LKS. GFS HAS MORE CLOUDS AND A WIDESPREAD LT -SN OF MAYBE
AN INCH. SAT NT INTO SUN FLOW BCMS ZONAL TO WSW AT 500HPA. WMFNT
AND SFC LOW SETS UP N OF RGN.
NOT MUCH DIFFERENCE BWTN GFS AND ECMWF. WILL POPULATE WITH HPC MID
SHIFT AND TWEAK POPS A TAD. OTHERWISE A QUIET PERIOD FOR THE
HOLIDAY WEEK.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
A FRONTAL BOUNDARY WILL BE OVER UPSTATE NY AND NEW ENGLAND TODAY
WITH AREAS OF LOW PRESSURE MOVING ALONG IT. THIS BOUNDARY WILL
DIVIDE VERY COLD AIR FROM MILD AIR OVER THE E-CNTRL NY CORRIDOR WITH
SOME FREEZING RAIN CONTINUING FOR KGFL EARLY THIS MORNING...AND
OCCASIONAL LIGHT RAIN FOR KALB-KPSF SOUTHWARD BEFORE A STEADIER
RAINSHIELD MOVES IN TOWARDS 12Z.
FLIGHT CONDITIONS VARY FROM LIFR/IFR AT KGFL/KALB TO VFR/MVFR AT
KPOU AND KPSF THIS MORNING. THE TREND WILL BE FOR WIDESPREAD
IFR/MVFR CONDITIONS TO IMPACT THE TERMINALS BTWN 09Z-12Z. THE MVFR
CONDITIONS MAY CONTINUE AT KPOU UNTIL AFTER 12Z...BUT EXPECT IFR
CIGS/VSBYS FOR KGFL...KALB...KPSF THROUGH MOST OF THE LATE MORNING
INTO THE EARLY PM...AS LOW PRESSURE MOVES ACROSS CNTRL/NRN NY.
EXPECT TEMPS TO MOVE BACK ABOVE FREEZING AT KGFL AROUND 10Z.
THE RAINFALL SHOULD DIMINISH BTWN 18Z-21Z FOR THE E-CNTRL NY
TERMINALS WITH SOME SCT SHOWERS AND DRIZZLE LINGERING INTO THE EARLY
EVENING. SOME IFR/MVFR VISIBILITIES MAY PERSIST INTO THE EARLY
EVENING WITH MVFR CIGS. THE CIGS MAY START TO RISE TOWARDS MIDNIGHT
WITH SOME DRIER AIR STARTING TO FILTER IN FROM THE SOUTHWEST.
THE SFC WINDS WILL BE FROM THE E TO NE AT KALB AND KGFL EARLY THIS
MORNING AT 5-10 KTS...THEN VEER TO TO SOUTH AT AROUND 10 KTS BY 12Z
WITH SOME GUSTS AT KALB IN THE 20-25 KT RANGE. KPOU AND KPSF WILL
CONTINUE TO HAVE S/SW WINDS 5-10 KTS...THEN INCREASE TO 8-15 KTS
WITH SOME GUSTS CLOSE TO 25 KTS AT KPSF...AS THE STRONGER LLJ MOVES
IN ALOFT. THE WINDS WILL DECREASE FROM THE S/SW AT LESS THAN 10 KTS
AFTER 00Z/MON.
OUTLOOK...
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
THURSDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THOUGH TONIGHT WITH
INCREASING SNOW MELT. LOW PRESSURE WILL MOVE ALONG A NEARLY
STATIONARY FRONT FROM THE NIAGARA FRONTIER TO NEW ENGLAND BY THIS
EVENING. 1-2 INCHES OF ADDITIONAL RAINFALL IS EXPECTED IN THE
ADIRONDACKS...WITH LESSER AMOUNTS SOUTH. TEMPERATURES TODAY WILL WARM
INTO THE 50S AND 60S REMAIN ABOVE FREEZING TONIGHT.
IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT
SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF
INCH...BUT ALMOST ALL THE SNOW WILL MELT. EVEN AS THE RAIN TAPERS
OFF THIS EVENING...SNOW MELT AND RUNOFF WILL CONTINUE TONIGHT.
IN THE SOUTH THE RAINFALL WILL BE SUFFICIENT FOR SIGNIFICANT
WITHIN BANK RISES...BUT FLOODING IS NOT EXPECTED AT THIS TIME.
THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK
VALLEY INTO THE ADIRONDACKS WHERE 1 TO 2 INCHES ADDITIONAL RAIN
AND UP TO AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED.
FLOOD WATCHES REMAIN IN EFFECT THROUGH TONIGHT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR
NYZ041>043-083-084.
FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ032-033-038>040-042-
043-082.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...FRUGIS
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...WASULA
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS NEW YORK NY
345 AM EST SUN DEC 22 2013
.SYNOPSIS...
A WARM FRONT WILL REMAIN ANCHORED NORTH OF THE TRI-STATE REGION
THROUGH SUNDAY. LOW PRESSURE RIDES ALONG A COLD FRONT MONDAY. THE
FRONT MOVES SLOWLY EAST TUESDAY. HIGH PRESSURE THEN BUILDS TOWARD
THE AREA WEDNESDAY. A COLD FRONT MOVES THROUGH LATE THURSDAY. HIGH
PRESSURE BUILDS LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE WATER VAPOR IMAGERY DEPICTS DIFFLUENT FLOW JUST WEST OF THE
TENNESSEE VALLEY WITH A STRONG SHORTWAVE AND VORTICITY MAXIMUM
MOVING ACROSS THE CENTRAL U.S. THE SURFACE LOW IS MOVING INTO THE
OHIO VALLEY. THE LOW IS FORECAST TO MAINTAIN ITS STRENGTH FOR THE
REMAINDER OF TONIGHT.
THE LOCAL AREA WILL RECEIVE A CONTINUOUS FLOW OUT OF THE SOUTH TO
SOUTHWEST...INCREASING THE WARM AND MOIST AIR ADVECTION. STRATUS HAS
BEGUN TO MOVE IN ACROSS PORTIONS OF LONG ISLAND. FOG HAS STARTED TO
DEVELOP BUT IS PATCHY IN COVERAGE WITHOUT TOO MUCH REDUCTION IN
VISIBILITY.
LOOKING AT LATEST BUFKIT SOUNDINGS...THE FOG LOOKS TO INCREASE BY
09Z AND LINGER INTO SUNDAY MORNING. KEEPING PATCHY COVERAGE OF FOG
UNTIL 08Z AND THEN EXPAND TO AREAS. MOST MOS GUIDANCE IS NOT
BRINGING MUCH LOWER VSBYS UNTIL AROUND 12-15Z WITH DENSE FOG
POTENTIAL. THE POTENTIAL WILL BE THERE FOR DENSE FOG AND THIS WILL
BE AN ADVECTION FOG. THE LIMITING FACTOR IS THE WINDS AND THIS CAN
BE CONVEYED BY ONGOING CONDITIONS. RELATIVELY HIGHER WINDS ALONG THE
COAST WITHOUT MUCH IF ANY VISIBILITY REDUCTION WITH A LITTLE MORE
REDUCTION INLAND WHERE WINDS ARE LIGHTER. IF WINDS FURTHER DECOUPLE
AND DECREASE...A MORE WIDESPREAD FOG WILL DEVELOP.
REGARDING SHOWERS...TRENDED LOWER IN POPS WITH SCATTERED SHOWERS
BEING RESTRICTED TO MAINLY INTERIOR PORTIONS. THIS IS CONSISTENT
WITH HRRR FORECAST REFLECTIVITY FIELDS. STILL EXPECTING SOME DRIZZLE
TO FORM TOWARDS MORNING WITH SATURATION OF THE BOUNDARY LAYER.
LOW TEMPERATURES FOR THE MOST PART HAVE ALREADY BEEN REACHED WITH A
STEADY TO SLIGHT INCREASE IN TEMPS EXPECTED TOWARDS MORNING.
TEMPERATURES WILL BE MOSTLY FROM LOW AND MID 40S TO MID 50S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
IF TEMPS WERE MIXED DOWN FROM H85...HIGHS WOULD BE IN THE LOW TO
MID 80S ON SUN. DESPITE THESE EXTREMELY WARM TEMPS ALOFT
HOWEVER...BOTH THE GFS AND NAM SUGGEST THE AREA WILL REMAIN
SOCKED IN WITH STRATUS...FG AND DZ THRU THE DAY. THIS SHOULD LIMIT
HIGHS SO WENT WITH THE COOLEST GUIDANCE...THE MET. MOST IF NOT ALL
CLIMATE SITES HOWEVER SHOULD STILL BREAK THEIR RECORDS.
IF THE CLOUDS DO BREAK UP IN THE EARLY AFTN...TEMPS WILL SHOOT UP
INTO 70S GENERALLY FROM THE CITY N AND W.
CONTINUED CHC FOR MEASUREABLE RAIN COVERED WITH -SHRA DURING THE
DAY...BUT THE MAIN FORCING DOES NOT ARRIVE TIL SUN NGT PER THE
NAM/GFS/ECMWF. FCST THEREFORE BRINGS POPS UP THRU THE NGT...AND
TRANSITIONS PCPN TO MODERATE RAIN. THIS IS WHEN THE BEST WINDOW
FOR ACCUMULATING PCPN WILL OCCUR. IT WILL REMAIN STEAMY WITH LOW
TEMPS ABV MAX NORMALS.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
SOUTHEAST RIDGE GIVES WAY TO DEEP TROUGH MONDAY AND TUESDAY. THE
TROUGH MOVES EAST WITH BRIEF RIDGING BY MID WEEK. AN UPSTREAM
SHORTWAVE MOVES ACROSS THE NORTHEAST BY LATE IN THE WEEK.
AT THE SFC...WAVE OF LOW PRESSURE RIDES ALONG THE STALLED OR SLOW
MOVING FRONT MONDAY. THIS FRONT TRACKS TO THE EAST...WITH AN
INVERTED TROUGH (ASSOCIATED WITH LARGE UPPER TROUGH) MOVING THROUGH
SOMETIME TUESDAY.
A TIGHT PRESSURE GRADIENT REMAINS IN PLACE MONDAY NIGHT THROUGH
TUESDAY NIGHT. THEN HIGH PRESSURE BUILDS IN WEDNESDAY AND WEDNESDAY
NIGHT. A COLD FRONT APPROACHES AND MOVES ACROSS THE AREA THURSDAY
AND THURSDAY NIGHT...WITH HIGH PRESSURE BUILDING BEHIND THE FRONT
LATE IN THE WEEK INTO NEXT WEEKEND.
MODELS IN GENERAL AGREEMENT WITH REGARD TO THESE OVERALL FEATURES AND
PATTERN THROUGH THE WEEK.
RAIN...MODERATE TO PERHAPS HEAVY AT TIMES...MONDAY WILL TAPER OFF
FROM WEST TO EAST LATE MONDAY AND MONDAY NIGHT. A FEW FLURRIES OR
LIGHT SNOW SHOWERS ARE POSSIBLE LATE TUESDAY AND TUESDAY
NIGHT...WITH WEAK INSTABILITY IN PLACE AS UPPER TROUGH MOVES
THROUGH. MOISTURE THOUGH WILL BE LIMITED.
DRY WEDNESDAY AND WEDNESDAY NIGHT...THEN A FEW MORE RAIN OR SNOW
SHOWERS ARE POSSIBLE WITH THE COLD FRONT LATE THURSDAY AND THURSDAY
NIGHT. DRY WEATHER RETURNS.
AS FOR TEMPS...LITTLE CHANGE IN TEMPS FROM EARLY MORNING READINGS
ARE EXPECTED MONDAY DUE TO THE CLOUDS AND RAIN. THEN A BRIEF SHOT OF
COLDER AIR MOVES IN MONDAY NIGHT THROUGH WEDNESDAY. NEAR NORMAL
TEMPS ARE EXPECTED THURSDAY IN WEAK WARM AIR ADVECTION BEHIND THE
HIGH AND AHEAD OF THE FRONT. THE SEASONABLY CHILLY WEATHER CONTINUES
LATE IN THE WEEK.
FOLLOWED A MAV/MET BLEND MONDAY...AND WPC/ECE AND MEX NUMBERS
FOLLOWED TUESDAY ONWARD.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
A FRONTAL BOUNDARY STRETCHING FROM JUST OFF THE TEXAS COAST THROUGH
THE OHIO VALLEY AND INTO NORTHERN NEW ENGLAND WILL SLOWLY MOVE EAST
THROUGH TODAY...THEN TRACK ACROSS THE TERMINALS LATE TONIGHT INTO
MONDAY MORNING.
TOUGH FORECAST CONTINUES AS THE STRATUS AND FOG HAS NOT YET
DEVELOPED...WITH LOCAL MVFR CONDITIONS. TREND TO BETTER CONDITIONS
CONTINUES. STILL HAVE LOW CONFIDENCE IN THE FORECAST.
MODERATE CONFIDENCE IN WINDS. A 55-65KT LLJ BETWEEN 1500-2000
FT...WILL PEAK BETWEEN 10Z AND 16Z. THINK SOME OF THIS WILL MIX
DOWN...WITH 20-30KT GUSTS BETWEEN 15Z AND 22Z.
SCATTERED SHOWERS APPROACHING FROM THE SW. KSWF HAS THE HIGHEST CHC
FOR ANY ACTIVITY TO IMPACT THE AIRFIELD. DIFFICULT TO PINPOINT WHERE
SCT SHOWERS WILL BE BEYOND 12Z...BUT ORGANIZED FRONTAL SHOWERS NOT
EXPECTED TO IMPACT OTHER TERMINALS UNTIL AFT 18Z.
.OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY...
.SUN NIGHT...MVFR-IFR IN FG/BR AND -SHRA.
.MON...MVFR-IFR IN -SHRA INTO THE AFTN...THEN CONDS IMPROVING W TO E.
WIND SHIFT FROM SW-NW WITH COLD FROPA AFTER 18Z.
.TUE...VFR. NW WIND 15-20G20-30KT.
.WED-THU...VFR.
&&
.MARINE...
REDUCED VSBY AND MODERATE SSW FLOW WILL RESULT IN HAZARDOUS
CONDITIONS THRU SUN NGT. A SCA FOR ALL WATERS EXCEPT THE HARBOR
TNGT THRU SUN NGT. STRONGEST WINDS ON THE ERN WATERS DUE TO THE SW
FETCH. IT IS UNCERTAIN IF THE WINDS WILL BE STRONG ENOUGH TO KEEP
FOG DEVELOPMENT LIMITED. HAVE INCLUDED 1NM VSBY IN THE FCST...BUT
POTENTIAL EXISTS FOR VSBY TO DROP BLW 1NM IF WINDS ARE WEAKER THAN
FCST. THIS WOULD REQUIRE A DENSE FG ADVY.
AS LOW PRESSURE PASSES ACROSS THE WATERS MONDAY...OCEAN SEAS REMAIN
ELEVATED. THEN THE LOW AND COLD FRONT DEPART...WITH GUSTY WEST TO
NORTHWEST WINDS ANTICIPATED MONDAY NIGHT THROUGH TUESDAY NIGHT. HIGH
PRESSURE EVENTUALLY BUILDS IN WEDNESDAY AND THURSDAY. AS
SUCH...WINDS WILL DIMINISH AND SEAS WILL SUBSIDE DURING THIS MID
WEEK TIMEFRAME.
&&
.HYDROLOGY...
SPOTTY LIGHT PCPN CAN BE EXPECTED THRU SUN. THIS WILL RESULT IN
MINOR ACCUMS. MOST OF THE MEASUREABLE RAIN IS FCST TO OCCUR SUN
NGT INTO MON. AROUND AN INCH OF BASIN AVE RAINFALL IS EXPECTED
ATTM.
&&
.CLIMATE...
THE FOLLOWING ARE RECORD HIGHS AND FORECAST HIGHS FOR SUNDAY
DECEMBER 22
RECORD FORECAST
EWR 65/1998 69
BDR 59/1998 59
NYC *63/1998 69
LGA 64/1998 67
JFK 62/1998 62
ISP 59/2011 62
* ALSO OCCURRED IN PREVIOUS YEARS
NOTE: RECORD HIGH MINIMUMS ARE ALSO POSSIBLE AT JFK AND ISP ON SUNDAY
DECEMBER 22. THE FORECAST LOW AT JFK IS 50 WITH A RECORD HIGH MINIMUM OF
50 IN 1990. THE FORECAST LOW AT ISP IS 53 WITH A RECORD HIGH MINIMUM OF
50 IN 1990.
THE FOLLOWING ARE THE RECORD HIGH MINIMUMS FOR MONDAY DECEMBER 23
RECORD FORECAST
EWR 58/1990 53
BDR 51/1990 49
NYC 57/1990 56
LGA 54/1990 56
JFK 50/1990 51
ISP 52/1990 54
&&
.EQUIPMENT...
THE NEW YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 IS
OUT OF SERVICE.
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD EMERGENCY
BROADCAST CHANNEL...THE NEW YORK CITY NOAA ALL HAZARDS WEATHER
RADIO STATION KWO35 IS OUT OF SERVICE.
DURING THE TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS WEATHER RADIO
DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE
WEEKLY TEST OF THE WARNING SYSTEM...AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST MONDAY FOR ANZ330-335-340-
345-350-353-355.
&&
$$
AVIATION...MET
AREA FORECAST DISCUSSION
NWS ALBANY NY
321 AM EST SUN DEC 22 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONTAL BOUNDARY FROM CENTRAL NEW YORK TO THE
MAINE COAST WILL SHIFT SLIGHTLY AS A STORM MOVES ALONG IT TODAY.
NORTH OF IT IT WILL BE CHILLY WITH RAIN AND FREEZING RAIN...WITH
RAIN AND VERY MILD WEATHER TO ITS SOUTH. THE STORM WILL DRAG A
COLD FRONT THROUGH THE REGION TONIGHT AND THEN SLIDE SLOWLY
OFFSHORE MONDAY. HIGH PRESSURE WILL BUILD FROM ONTARIO INTO NEW
YORK TUES INTO CHRISTMAS...WITH SURGES OF MUCH COLD AIR FILTERING
INTO THE REGION. THE WEEK WILL END WITH A SERIES OF FAST MOVING
WEATHER SYSTEMS WITH BOUTS OF SNOW SHOWERS AND GENERALLY
SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 321 AM EST...WIDE VARIETY OF TEMPERATURES ACROSS THE REGION
EARLY THIS MORNING WITH STALLED FRONTAL BOUNDARY SITUATED DIRECTLY
ACROSS THE CENTRAL PORTION OF THE CWA. NORTH OF THE
BOUNDARY...VERY COLD CANADIAN AIR IS PULLED SOUTHWARD THANKS TO A
LOW LEVEL NNE FLOW THROUGH THE CHAMPLAIN VALLEY AND INTO THE UPPER
HUDSON VALLEY REGION. THIS HAS ALLOWED TEMPS TO DROP BELOW
FREEZING FOR THE GLENS FALLS AND SARATOGA SPRINGS AREA. TEMPS HAVE
FALLEN INTO THE MID 30S IN THE CAPITAL REGION.
AT THE SAME TIME...VERY WARM TEMPS ALOFT ARE IN PLACE THANKS TO A
STRONG SOUTHERLY FLOW ALOFT. 850 HPA TEMPS HAVE RISEN TO +7 TO +15
DEGREES C ACROSS OUR REGION. AS A RESULT...THE WARMER TEMPS AT THIS
HOUR ARE ACROSS THE MOUNTAIN PEAKS OF THE CATSKILLS...SRN GREENS AND
BERKSHIRES...WHERE TEMPS ARE WELL INTO THE 50S.
WITH AN APPROACHING LOW PRESSURE AREA AND THE SFC BOUNDARY IN
PLACE...OVERRUNNING PRECIP...MAINLY IN THE FORM OF RAIN...IS MOVING
ACROSS THE WESTERN ADIRONDACKS. SOME LIGHTER RAIN AND FREEZING RAIN
IS OCCURRING FURTHER EAST ACROSS THE LAKE GEORGE/SARATOGA REGION AND
SOME LIGHT RAIN SHOWERS ARE OVER WESTERN NEW ENGLAND. THERE IS A
BREAK IN THE PRECIP OVER THE REMAINDER OF THE AREA...AS A DRY SLOT
IS ATTEMPTING TO MOVE INTO THE AREA WITH LITTLE PRECIP SHOWN ON
UPSTREAM RADARS. THE LATEST 03Z 3KM HRRR SHOWS THIS DRY SLOT SHOULD
START TO FILL IN TOWARDS DAYBREAK AS THE LOW PRESSURE AREA MOVES
NORTHEAST ACROSS THE OHIO VALLEY AND EVENTUALLY TOWARDS UPSTATE
NY...SO WE WILL CONTINUE RATHER HIGH POPS BY AROUND DAYBREAK DESPITE
THE CURRENT LULL IN THE PRECIP AS SHOWN ON RADAR. FOR NOW...IT
DOESN/T APPEAR THAT THE CAPITAL REGION WILL BE SEEING ANY FREEZING
RAIN...AS THE APPROACHING STORM SHOULD ALLOW THE STALLED BOUNDARY TO
START TO MOVE NORTHWARD AS A WARM FRONT...AND BRING THE ALBANY AREA
INTO THE WARM SECTOR ONCE THE NEXT ROUND OF RAINFALL BEGINS.
FURTHER NORTH...IT MAY TAKE UNTIL THE MID TO LATE MORNING FOR THE
WARM FRONT TO MOVE THROUGH AND TEMPS TO WARM UP. AS A RESULT...A
PROLONGED PERIOD OF FREEZING RAIN CAN BE EXPECTED ACROSS THE LAKE
GEORGE SARATOGA REGION. ICE ACCRETION AMOUNTS WILL RANGE FROM A
TRACE TO A TENTH ACROSS THE SARATOGA SPRINGS AREA TO A FEW TENTHS
FOR GLENS FALLS TO ABOUT FOUR TENTHS ACROSS THE NORTH END OF LAKE
GEORGE. ASIDE FROM SOME HAZARDOUS DRIVING CONDITIONS...THIS MAY LEAD
TO SOME ISOLATED POWER OUTAGES.
AREAS IN THE WARM SECTOR SHOULD SEE SFC TEMPS WARM
SIGNIFICANTLY...AS THOSE WARMER TEMPS ALOFT ARE MIXED IN THE
BOUNDARY LAYER. MAX TEMPS LOOK TO REACH INTO THE 50S ACROSS MUCH OF
THE CENTRAL AND SOUTHERN PARTS OF THE AREA...WITH SOME LOW TO MID
60S FOR THE MID HUDSON VALLEY.
WHILE IT WILL RAIN THROUGH THE MORNING HOURS...MOST AREAS WILL BE
DONE SEEING PRECIPITATION BY THE EARLY TO MID AFTN HOURS...AS THE
STORM/S COLD FRONT PASSES THROUGH THE AREA. TOTAL RAINFALL FOR
SUNDAY WILL RANGE FROM JUST A QUARTER OF AN INCH ACROSS LITCHFIELD
COUNTY CT...TO AROUND THREE QUARTERS OF AN INCH IN THE CAPITAL
REGION TO ABOUT AN INCH AND A HALF OVER THE ADIRONDACKS. SEE THE
HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL TO AFFECT AREA RIVERS
AND STREAMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
FOR THIS PERIOD THE MODEL SUITE (GEM/GFS/ECMWF) ARE IN FAIRLY
GOOD AGREEMENT. DURING THE THIS EVENING THE SFC LOW AND ITS UPPER
DYNAMICS WILL LIFT NE OUT OF FCA. A SERIES OF 500HPA SHORT WAVES
WILL DIG A TROF OVER GRTLKS...MAINTAINING A STRONG SW 500HPA FLOW
OVER THE EASTERN THIRD OF THE NATION. FOR A TIME THIS WILL ACT TO
WEAKEN THE SFC LOW FURTHER OVER NEW ENG...BUT THE SFC LOW WILL
DRAG A CDFNT THROUGH THE REGION TNGT. GIVEN THE UPPER FLOW COOLER
AIR WILL BE SLOW TO FILTER IN OVERNIGHT....AND TEMPS WILL REMAIN
ABV FREEZING IN MOST AREAS...WITH SNOW MELT CONTINUING.
BY MONDAY THIS CDFNT WILL NEARLY STALL ALONG THE EASTERN
SEABOARD...AND WITH DIGGING 500HPA TROF INTERACTING WITH THE
COASTAL BAROCLINIC ZONE WILL TRIGGER A BOUT OF OVERRUNINNG RAIN...ALONG
THE I-95 CORRIDOR THAT WILL BACK BUILD INTO SE PORTIONS OF FCA.
QPF DURING MONDAY WITH THIS SHOULD BE 0.25 TO 0.50 IN THESE
AREAS...AND GIVEN THESE AREAS WERE IN THE WARM SECTOR MUCH OF THE
CURRENT EVENT...THEY MELTED MOST OF THEIR SNOW...BUT HAD LITTLE
RAINFALL. ADD TO THAT THE 2-3 DAYS THIS OCCURRED...THE ADDITIONAL
RAIN IN SOUTHEAST AREAS MONDAY SHOULD NOT RESULT IN ANYTHING OTHER
THAN WITHIN BANK RISES.
FURTHER WEST MONDAY AS HIGH PRESSURE BUILDS EAST WIND GRADIENT
WILL INCR AND AS THE 500HPA TROF PUSHES EAST A MUCH STRONGER 2NDRY
CDFNT WILL PUSH INTO THE REGION LATE MONDAY AND THROUGH MONDAY
NIGHT. TEMPS MONDAY WILL HOLDS STEADY THEN FALL DURING THE AFTN.
MONDAY NIGHT INTO TUES THE PASSAGE OF THE 500HPA TROF...CAA WILL
RESULT IN SCT -SHSN ACTIVITY. HWVR LLVL FLOW WILL BE TOTALLY
UNFAVORABLE FOR LK EFFECT OVER EASTERN NY.
ONCE THE 500HPA TROF EXITS CHRISTMAS EVE BOTH A 500HPA RIDGE...AND
SFC HIGH PRESSURE WILL SETTLE OVER NYS AND MID ATLC REGION. THIS
WILL SET THE STAGE FOR A FRIGID NIGHT WITH IDEAL RADIATIONAL
COOLING...ONE OF THE LONGEST NIGHTS OF THE YEAR...CLEAR SKIES AND
DRY AIR MASS. LOWS WILL PLUNGE TO -20F IN PARTS OF THE ADIRONDACKS
TO AROUND 10 IN THE SE.
TEMPS WILL RECOVER CHRISTMAS DAY TO THE TEENS AND 20S AS SFC HIGH
SLIDES OFFSHORE. SOME CLOUDS MAY ARRIVE IN THE AFTERNOON AS NEXT
WEAK SYSTEM APPROACHES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE EFP WILL FEATURE A SERIES OF FAST MOVING SYSTEMS IN W-NW FLOW.
MOST WILL BE FAIRLY WK CDFNTS AND/OR 500HPA SHORT WVS...WHICH
WILL INCR CLOUDS AND PRODUCE SCT -SHSN AND AT TIMES HAVE SOME
INTERACTION WITH THE GRTLKS. TEMPS WILL RETURN TO NEAR NORMALS
AFTER A FRIGID CHRISTMAS. TYPICAL WINTER IN UPSTATE NY.
CHRISTMAS NIGHT AND THURS THE FIRST OF THESE SYSTEMS RACES ACROSS
ONTARIO...WITH A FEW WEAK FRONTS AND A 500HPA SHORT WV. MAIN
IMPACTS WILL INCR CLOUDS MAINLY N & W. THU NT IT WILL DRAG A
CDFNT THROUGH WITH SOME -SHSN ACTIVITY MAINLY N & WEST. IN ITS
WAKE FRI CAA AND A 2NDARY CDFNT AND NW FLOW WILL TRIGGER SCT -SHSN
WITH SOME LK ASSISTANCE. WK SFC HIGH BUILDS OVER FCA FRI NT.
SAT ANOTHER WK SHORT WV AND SFC SYSTEM MOVES THROUGH THE GRTLKS
WITH A LITTLE WAA INCRG CLOUDS AND SCT -SHSN IN ECMWF...GETTING SOME
ASSIST FM THE LKS. GFS HAS MORE CLOUDS AND A WIDESPREAD LT -SN OF MAYBE
AN INCH. SAT NT INTO SUN FLOW BCMS ZONAL TO WSW AT 500HPA. WMFNT
AND SFC LOW SETS UP N OF RGN.
NOT MUCH DIFFERENCE BWTN GFS AND ECMWF. WILL POPULATE WITH HPC MID
SHIFT AND TWEAK POPS A TAD. OTHERWISE A QUIET PERIOD FOR THE
HOLIDAY WEEK.
&&
.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
A FRONTAL BOUNDARY WILL BE OVER UPSTATE NY AND NEW ENGLAND TODAY
WITH AREAS OF LOW PRESSURE MOVING ALONG IT. THIS BOUNDARY WILL
DIVIDE VERY COLD AIR FROM MILD AIR OVER THE E-CNTRL NY CORRIDOR WITH
SOME FREEZING RAIN CONTINUING FOR KGFL EARLY THIS MORNING...AND
OCCASIONAL LIGHT RAIN FOR KALB-KPSF SOUTHWARD BEFORE A STEADIER
RAINSHIELD MOVES IN TOWARDS 12Z.
FLIGHT CONDITIONS VARY FROM LIFR/IFR AT KGFL/KALB TO VFR/MVFR AT
KPOU AND KPSF THIS MORNING. THE TREND WILL BE FOR WIDESPREAD
IFR/MVFR CONDITIONS TO IMPACT THE TERMINALS BTWN 09Z-12Z. THE MVFR
CONDITIONS MAY CONTINUE AT KPOU UNTIL AFTER 12Z...BUT EXPECT IFR
CIGS/VSBYS FOR KGFL...KALB...KPSF THROUGH MOST OF THE LATE MORNING
INTO THE EARLY PM...AS LOW PRESSURE MOVES ACROSS CNTRL/NRN NY.
EXPECT TEMPS TO MOVE BACK ABOVE FREEZING AT KGFL AROUND 10Z.
THE RAINFALL SHOULD DIMINISH BTWN 18Z-21Z FOR THE E-CNTRL NY
TERMINALS WITH SOME SCT SHOWERS AND DRIZZLE LINGERING INTO THE EARLY
EVENING. SOME IFR/MVFR VISIBILITIES MAY PERSIST INTO THE EARLY
EVENING WITH MVFR CIGS. THE CIGS MAY START TO RISE TOWARDS MIDNIGHT
WITH SOME DRIER AIR STARTING TO FILTER IN FROM THE SOUTHWEST.
THE SFC WINDS WILL BE FROM THE E TO NE AT KALB AND KGFL EARLY THIS
MORNING AT 5-10 KTS...THEN VEER TO TO SOUTH AT AROUND 10 KTS BY 12Z
WITH SOME GUSTS AT KALB IN THE 20-25 KT RANGE. KPOU AND KPSF WILL
CONTINUE TO HAVE S/SW WINDS 5-10 KTS...THEN INCREASE TO 8-15 KTS
WITH SOME GUSTS CLOSE TO 25 KTS AT KPSF...AS THE STRONGER LLJ MOVES
IN ALOFT. THE WINDS WILL DECREASE FROM THE S/SW AT LESS THAN 10 KTS
AFTER 00Z/MON.
OUTLOOK...
SUNDAY NIGHT: MODERATE OPERATIONAL IMPACT. BREEZY CHANCE OF SHRA.
MONDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
TUESDAY: LOW OPERATIONAL IMPACT. BREEZY. SLIGHT CHANCE OF SHSN.
TUESDAY NIGHT: LOW OPERATIONAL IMPACT. BREEZY. NO SIG WX.
CHRISTMAS DAY TO THURSDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THROUGH THE
WEEKEND WITH INCREASING SNOW MELT. MEANWHILE A SERIES OF LOW
PRESSURE SYSTEMS WILL BE PROPAGATING ALONG A NEARLY STATIONARY
FRONT FROM THE NIAGARA FRONTIER TO VERMONT WITH 1-3 INCHES OF RAIN
EXPECTED IN THE ADIRONDACKS...BUT LESSER AMOUNTS SOUTH.
TEMPERATURES SUNDAY ARE EXPECTED TO WARM INTO THE 50S AND 60S.
IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT
SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF
INCH...BUT ALMOST ALL THE SNOW WILL MELT. IN THE SOUTH THIS WILL BE
SUFFICIENT FOR SIGNIFICANT WITHIN BANK RISES...BUT FLOODING IS NOT
EXPECTED AT THIS TIME.
THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK
VALLEY INTO THE ADIRONDACKS WHERE 1 TO 3 INCHES OF RAIN AND UP TO
AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED. FLOOD
WATCHES HAVE BEEN ISSUED FOR TONIGHT THROUGH SUNDAY NIGHT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR
NYZ041>043-083-084.
FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ032-033-038>040-042-
043-082.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...FRUGIS
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...WASULA
HYDROLOGY...GJM/SNYDER
AREA FORECAST DISCUSSION...CORRECTED
NWS NEW YORK NY
125 AM EST SUN DEC 22 2013
.SYNOPSIS...
A WARM FRONT WILL REMAIN ANCHORED NORTH OF THE TRI-STATE REGION
THROUGH SUNDAY. LOW PRESSURE RIDES ALONG A COLD FRONT MONDAY. THE
FRONT MOVES SLOWLY EAST TUESDAY. HIGH PRESSURE THEN BUILDS TOWARD
THE AREA WEDNESDAY. A COLD FRONT MOVES THROUGH LATE THURSDAY. HIGH
PRESSURE BUILDS LATE IN THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
THE WATER VAPOR IMAGERY DEPICTS DIFFLUENT FLOW JUST WEST OF THE
TENNESSEE VALLEY WITH A STRONG SHORTWAVE AND VORTICITY MAXIMUM
MOVING ACROSS THE CENTRAL U.S. THE SURFACE LOW IS MOVING INTO THE
OHIO VALLEY. THE LOW IS FORECAST TO MAINTAIN ITS STRENGTH FOR THE
REMAINDER OF TONIGHT.
THE LOCAL AREA WILL RECEIVE A CONTINUOUS FLOW OUT OF THE SOUTH TO
SOUTHWEST...INCREASING THE WARM AND MOIST AIR ADVECTION. STRATUS HAS
BEGUN TO MOVE IN ACROSS PORTIONS OF LONG ISLAND. FOG HAS STARTED TO
DEVELOP BUT IS PATCHY IN COVERAGE WITHOUT TOO MUCH REDUCTION IN
VISIBILITY.
LOOKING AT LATEST BUFKIT SOUNDINGS...THE FOG LOOKS TO INCREASE BY
09Z AND LINGER INTO SUNDAY MORNING. KEEPING PATCHY COVERAGE OF FOG
UNTIL 08Z AND THEN EXPAND TO AREAS. MOST MOS GUIDANCE IS NOT
BRINGING MUCH LOWER VSBYS UNTIL AROUND 12-15Z WITH DENSE FOG
POTENTIAL. THE POTENTIAL WILL BE THERE FOR DENSE FOG AND THIS WILL
BE AN ADVECTION FOG. THE LIMITING FACTOR IS THE WINDS AND THIS CAN
BE CONVEYED BY ONGOING CONDITIONS. RELATIVELY HIGHER WINDS ALONG THE
COAST WITHOUT MUCH IF ANY VISIBILITY REDUCTION WITH A LITTLE MORE
REDUCTION INLAND WHERE WINDS ARE LIGHTER. IF WINDS FURTHER DECOUPLE
AND DECREASE...A MORE WIDESPREAD FOG WILL DEVELOP.
REGARDING SHOWERS...TRENDED LOWER IN POPS WITH SCATTERED SHOWERS
BEING RESTRICTED TO MAINLY INTERIOR PORTIONS. THIS IS CONSISTENT
WITH HRRR FORECAST REFLECTIVITY FIELDS. STILL EXPECTING SOME DRIZZLE
TO FORM TOWARDS MORNING WITH SATURATION OF THE BOUNDARY LAYER.
LOW TEMPERATURES FOR THE MOST PART HAVE ALREADY BEEN REACHED WITH A
STEADY TO SLIGHT INCREASE IN TEMPS EXPECTED TOWARDS MORNING.
TEMPERATURES WILL BE MOSTLY FROM LOW AND MID 40S TO MID 50S.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/...
IF TEMPS WERE MIXED DOWN FROM H85...HIGHS WOULD BE IN THE LOW TO
MID 80S ON SUN. DESPITE THESE EXTREMELY WARM TEMPS ALOFT
HOWEVER...BOTH THE GFS AND NAM SUGGEST THE AREA WILL REMAIN
SOCKED IN WITH STRATUS...FG AND DZ THRU THE DAY. THIS SHOULD LIMIT
HIGHS SO WENT WITH THE COOLEST GUIDANCE...THE MET. MOST IF NOT ALL
CLIMATE SITES HOWEVER SHOULD STILL BREAK THEIR RECORDS.
IF THE CLOUDS DO BREAK UP IN THE EARLY AFTN...TEMPS WILL SHOOT UP
INTO 70S GENERALLY FROM THE CITY N AND W.
CONTINUED CHC FOR MEASUREABLE RAIN COVERED WITH -SHRA DURING THE
DAY...BUT THE MAIN FORCING DOES NOT ARRIVE TIL SUN NGT PER THE
NAM/GFS/ECMWF. FCST THEREFORE BRINGS POPS UP THRU THE NGT...AND
TRANSITIONS PCPN TO MODERATE RAIN. THIS IS WHEN THE BEST WINDOW
FOR ACCUMULATING PCPN WILL OCCUR. IT WILL REMAIN STEAMY WITH LOW
TEMPS ABV MAX NORMALS.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
SOUTHEAST RIDGE GIVES WAY TO DEEP TROUGH MONDAY AND TUESDAY. THE
TROUGH MOVES EAST WITH BRIEF RIDGING BY MID WEEK. AN UPSTREAM
SHORTWAVE MOVES ACROSS THE NORTHEAST BY LATE IN THE WEEK.
AT THE SFC...WAVE OF LOW PRESSURE RIDES ALONG THE STALLED OR SLOW
MOVING FRONT MONDAY. THIS FRONT TRACKS TO THE EAST...WITH AN
INVERTED TROUGH (ASSOCIATED WITH LARGE UPPER TROUGH) MOVING THROUGH
SOMETIME TUESDAY.
A TIGHT PRESSURE GRADIENT REMAINS IN PLACE MONDAY NIGHT THROUGH
TUESDAY NIGHT. THEN HIGH PRESSURE BUILDS IN WEDNESDAY AND WEDNESDAY
NIGHT. A COLD FRONT APPROACHES AND MOVES ACROSS THE AREA THURSDAY
AND THURSDAY NIGHT...WITH HIGH PRESSURE BUILDING BEHIND THE FRONT
LATE IN THE WEEK INTO NEXT WEEKEND.
MODELS IN GENERAL AGREEMENT WITH REGARD TO THESE OVERALL FEATURES AND
PATTERN THROUGH THE WEEK.
RAIN...MODERATE TO PERHAPS HEAVY AT TIMES...MONDAY WILL TAPER OFF
FROM WEST TO EAST LATE MONDAY AND MONDAY NIGHT. A FEW FLURRIES OR
LIGHT SNOW SHOWERS ARE POSSIBLE LATE TUESDAY AND TUESDAY
NIGHT...WITH WEAK INSTABILITY IN PLACE AS UPPER TROUGH MOVES
THROUGH. MOISTURE THOUGH WILL BE LIMITED.
DRY WEDNESDAY AND WEDNESDAY NIGHT...THEN A FEW MORE RAIN OR SNOW
SHOWERS ARE POSSIBLE WITH THE COLD FRONT LATE THURSDAY AND THURSDAY
NIGHT. DRY WEATHER RETURNS.
AS FOR TEMPS...LITTLE CHANGE IN TEMPS FROM EARLY MORNING READINGS
ARE EXPECTED MONDAY DUE TO THE CLOUDS AND RAIN. THEN A BRIEF SHOT OF
COLDER AIR MOVES IN MONDAY NIGHT THROUGH WEDNESDAY. NEAR NORMAL
TEMPS ARE EXPECTED THURSDAY IN WEAK WARM AIR ADVECTION BEHIND THE
HIGH AND AHEAD OF THE FRONT. THE SEASONABLY CHILLY WEATHER CONTINUES
LATE IN THE WEEK.
FOLLOWED A MAV/MET BLEND MONDAY...AND WPC/ECE AND MEX NUMBERS
FOLLOWED TUESDAY ONWARD.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
A FRONTAL BOUNDARY STRETCHING FROM JUST OFF THE TEXAS COAST THROUGH
THE OHIO VALLEY AND INTO NORTHERN NEW ENGLAND WILL SLOWLY MOVE
EAST THROUGH SUN THEN TRACK ACROSS THE TERMINALS LATE SUN NIGHT
INTO MONDAY MORNING.
DIFFICULT FORECAST THE NEXT 24 HOURS. THEREFORE...06Z TAFS ARE A
LOW TO MODERATE CONFIDENCE FORECAST.
STRATUS/FOG FINALLY DEVELOPING WITH IFR CONDS AT KGON/KISP. 00Z
GUIDANCE SLIGHTLY MORE OPTIMISTIC LATE TONIGHT AND SUN AND SINCE
CONDS AT W TERMINALS WILL TAKE A FEW MORE HOURS TO DROP...HAVE
SIDED WITH THIS THINKING. EXCEPTIONS BEING KJFK/KHPN WHICH SHOULD DROP
TO LIFR AROUND DAYBREAK. GUIDANCE CONTINUES TO VARY IN TIMING AND
FLIGHT CAT AFT 12Z.
MODERATE CONFIDENCE IN WINDS. A 55-65KT LLJ BETWEEN 1500-2000
FT...WILL PEAK BETWEEN 10Z AND 16Z. ALREADY SEEING 55KT AT 2K FT
IN 435Z ACARS SOUNDING FROM KEWR. THINK SOME OF THIS WILL MIX
DOWN...WITH 20-30KT GUSTS BETWEEN 15Z AND 22Z.
SHOWERS APPROACHING FROM THE SW. LOOKS LIKE THEY MAY JUST MISS
KEWR/KTEB/KHPN BUT WILL NEED TO MONITOR AS THEY GET CLOSER. KSWF
HAS THE HIGHEST CHC FOR ANY ACTIVITY TO IMPACT THE AIRFIELD.
DIFFICULT TO PINPOINT WHERE SCT SHOWERS WILL BE BEYOND 12Z...BUT
ORGANIZED FRONTAL SHOWERS NOT EXPECTED TO IMPACT OTHER TERMINALS
UNTIL AFT 18Z.
.OUTLOOK FOR 06Z MONDAY THROUGH THURSDAY...
.SUN NIGHT...MVFR-IFR IN FG/BR AND -SHRA.
.MON...MVFR-IFR IN -SHRA INTO THE AFTN...THEN CONDS IMPROVING W TO E.
WIND SHIFT FROM SW-NW WITH COLD FROPA AFTER 18Z.
.TUE...VFR. NW WIND 15-20G20-30KT.
.WED-THU...VFR.
&&
.MARINE...
REDUCED VSBY AND MODERATE SSW FLOW WILL RESULT IN HAZARDOUS
CONDITIONS THRU SUN NGT. A SCA FOR ALL WATERS EXCEPT THE HARBOR
TNGT THRU SUN NGT. STRONGEST WINDS ON THE ERN WATERS DUE TO THE SW
FETCH. IT IS UNCERTAIN IF THE WINDS WILL BE STRONG ENOUGH TO KEEP
FOG DEVELOPMENT LIMITED. HAVE INCLUDED 1NM VSBY IN THE FCST...BUT
POTENTIAL EXISTS FOR VSBY TO DROP BLW 1NM IF WINDS ARE WEAKER THAN
FCST. THIS WOULD REQUIRE A DENSE FG ADVY.
AS LOW PRESSURE PASSES ACROSS THE WATERS MONDAY...OCEAN SEAS REMAIN
ELEVATED. THEN THE LOW AND COLD FRONT DEPART...WITH GUSTY WEST TO
NORTHWEST WINDS ANTICIPATED MONDAY NIGHT THROUGH TUESDAY NIGHT. HIGH
PRESSURE EVENTUALLY BUILDS IN WEDNESDAY AND THURSDAY. AS
SUCH...WINDS WILL DIMINISH AND SEAS WILL SUBSIDE DURING THIS MID
WEEK TIMEFRAME.
&&
.HYDROLOGY...
SPOTTY LIGHT PCPN CAN BE EXPECTED THRU SUN. THIS WILL RESULT IN
MINOR ACCUMS. MOST OF THE MEASUREABLE RAIN IS FCST TO OCCUR SUN
NGT INTO MON. AROUND AN INCH OF BASIN AVE RAINFALL IS EXPECTED
ATTM.
&&
.CLIMATE...
THE FOLLOWING ARE RECORD HIGHS AND FORECAST HIGHS FOR SUNDAY
DECEMBER 22
RECORD FORECAST
EWR 65/1998 69
BDR 59/1998 59
NYC *63/1998 69
LGA 64/1998 67
JFK 62/1998 62
ISP 59/2011 62
* ALSO OCCURRED IN PREVIOUS YEARS
NOTE: RECORD HIGH MINIMUMS ARE ALSO POSSIBLE AT JFK AND ISP ON SUNDAY
DECEMBER 22. THE FORECAST LOW AT JFK IS 50 WITH A RECORD HIGH MINIMUM OF
50 IN 1990. THE FORECAST LOW AT ISP IS 53 WITH A RECORD HIGH MINIMUM OF
50 IN 1990.
THE FOLLOWING ARE THE RECORD HIGH MINIMUMS FOR MONDAY DECEMBER 23
RECORD FORECAST
EWR 58/1990 53
BDR 51/1990 49
NYC 57/1990 56
LGA 54/1990 56
JFK 50/1990 51
ISP 52/1990 54
&&
.EQUIPMENT...
THE NEW YORK CITY NOAA ALL HAZARDS WEATHER RADIO STATION KWO35 IS
OUT OF SERVICE.
DUE TO INTERFERENCE ISSUES WITH THE U.S. COAST GUARD EMERGENCY
BROADCAST CHANNEL...THE NEW YORK CITY NOAA ALL HAZARDS WEATHER
RADIO STATION KWO35 IS OUT OF SERVICE.
DURING THE TIME...THE TRANSMITTER MAY BE RETURNED TO SERVICE
INTERMITTENTLY FOR USE OF THE NOAA ALL HAZARDS WEATHER RADIO
DURING POTENTIALLY DANGEROUS WEATHER SITUATIONS...FOR ROUTINE
WEEKLY TEST OF THE WARNING SYSTEM...AND TO DETERMINE IF THE
INTERFERENCE ISSUE HAS BEEN RESOLVED.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST MONDAY FOR ANZ330-335-340-
345-350-353-355.
&&
$$
SYNOPSIS...JMC/PW
NEAR TERM...JM
SHORT TERM...JMC
LONG TERM...PW
AVIATION...24
MARINE...JMC/PW
HYDROLOGY...JMC
CLIMATE...
EQUIPMENT...
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1119 PM CST SAT DEC 21 2013
.UPDATE...
UPDATE ISSUED AT 922 PM CST SAT DEC 21 2013
NO MAJOR CHANGES HAVE BEEN MADE THIS EVENING WITH REGARD TO THE
IMPACTS OF THE WINTER STORM. HOWEVER...HERE IS AN UPDATE OF WHERE
THINGS STAND. WE ARE IN THE BRIEF LULL IN STRONG FORCING BETWEEN
THE EARLIER WAA PCPN OVER THE SOUTHEAST 1/3 AND THE UPCOMING
STRONG DEFORMATION ZONE SPREADING NORTHEAST FROM MISSOURI. IN THE
MEAN TIME...WIDESPREAD LIGHT FREEZING DRIZZLE/LIGHT SNOW/LIGHT
SLEET CONTINUES OVER THE CWA. THE SNOW TO SLEET LINE SEEMS TO
CURRENTLY BE FROM NEAR BURLINGTON TO JUST EAST OF MOLINE...TO
DE KALB ILLINOIS. NORTHWEST OF THIS LINE...THE DOMINANT P-TYPE IS
SNOW...AND IT WILL CONTINUE TO BE SO. THE RAP MODEL WHICH IS
HANDLING THE 800MB WARM WEDGE NOTED ON THE 00Z DVN
SOUNDING...SHOWS A TRANSITION TO SNOW OVER THE REMAINING CWA
BETWEEN NOW AND 3 AM. HRRR AND RAP...ALONG WITH THE 00Z NAM
INDICATE THE DEFORMATION ZONE SHOULD HIT HARD SOMETIME ABOUT 10 PM
WEST...11 CENTRAL...TO MIDNIGHT NORTHEAST. IT SHOULD LAST THROUGH
15Z OR SO BEFORE RAPIDLY LIFTING NORTH OUT OF THE REGION.
THUS...HEAVY SNOW RATES FOR ABOUT 5 HOURS SEEM LIKELY IN OUR
WESTERN 1/2 TO 2/3RD...MATCHING AMOUNTS WELL ENOUGH NOT THE CHANGE
THEM.
ERVIN
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 318 PM CST SAT DEC 21 2013
VIGOROUS WINTER STORM NOW IMPINGING ON THE REGION. STORM IS
LARGELY EVOLVING AS FORECAST. WARM WEDGE ALOFT RESULTING IN FREEZING
RAIN OVER WEST CENTRAL AND CENTRAL ILLINOIS. SURFACE LOW NOW OVER
ARKANSAS WILL TRACK UP THE OHIO VALLEY. EXPECT TO SEE PRECIP
SHIELD SPREAD BACK TO THE NORTHWEST SLIGHTLY MORE INTO OUR AREA AS
THE LOW PASSES TO OUR SOUTHEAST...RESULTING ANOTHER PERIOD OF
MIXED PRECIP THIS EVENING FOR SOUTHEAST. FORECAST SOUNDINGS VIA
AWIPS AND BUFKIT SHOW CONTINUED POTENTIAL FOR FREEZING RAIN UNTIL
MIDNIGHT THEN FAIRLY RAPID TRANSITION TO SNOW AS THE MAIN WAVE
APPROACHES.
MAIN SNOWFALL EVENT WILL BE ASSOCIATED WITH THE DEFORMATION ZONE
MOVING ACROSS THE AREA TONIGHT. ENERGY ASSOCIATED WITH PRECIP NOW
OVER EASTERN OK AND KS WILL CONGEAL INTO INTENSE DEFORMATION ZONE
ACROSS NORTHERN MO AND EASTERN IA THIS EVENING. IMPRESSIVE
MOISTURE FOR THIS TIME OF YEAR WILL ONLY BE OFFSET BY RAPID
MOVEMENT OF SYSTEM. STILL...WE ARE LOOKING AT A PERIOD OF INTENSE
SNOWFALL RATES FROM LATE EVENING INTO EARLY MORNING.
WINDS BEGIN TO INCREASE TOWARD MORNING...CREATING POTENTIAL FOR
BLOWING SNOW ISSUES...ESPECIALLY IN RURAL AREAS SUNDAY.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 318 PM CST SAT DEC 21 2013
LIGHT SNOW FROM THE WINTER STORM WILL CONTINUE INTO SUNDAY EVENING
AND SLOWLY END ALONG WITH DECREASING WINDS. CLOUD COVER WILL AID IN
KEEPING TEMPERATURES UP BUT THE POSSIBILITY DOES EXIST THAT
HEADLINES FOR WIND CHILL MIGHT BE NEEDED OVER PART OF THE WESTERN
THIRD LATE SUNDAY NIGHT INTO MONDAY MORNING.
WRAP AROUND MOISTURE AND COLD AIR MOVING INTO THE AREA IS EXPECTED
TO KEEP FLURRIES OR VERY LIGHT SNOW GOING FOR A GOOD PART OF MONDAY
OVER THE NORTHEAST HALF OF THE AREA. THE STRENGTH OF THE COLD AIR
MOVING INTO THE AREA IS EXPECTED TO KEEP TEMPERATURES IN THE SINGLE
DIGITS OVER MUCH OF THE AREA.
ARCTIC HIGH PRESSURE MOVES ACROSS THE AREA MONDAY NIGHT INTO TUESDAY
RESULTING IN DRY CONDITIONS BUT BITTER COLD TEMPERATURES. BASED ON
PROJECTED LOWS AND WINDS...HEADLINES FOR WIND CHILL WOULD BE NEEDED
MONDAY NIGHT INTO TUESDAY MORNING.
SKIES SHOULD CLEAR MONDAY NIGHT AND WHEN COMBINED WITH FRESH SNOW
AND DECREASING WINDS IS EXPECTED TO PUSH LOW TEMPERATURES WELL BELOW
ZERO OVER MUCH OF THE AREA. LOWS MAY PUSH 20 BELOW IN THE FAVORED
COLD AREAS WEST OF THE MISSISSIPPI.
ON TUESDAY DRY CONDITIONS BUT VERY COLD TEMPERATURES WILL BE SEEN
ACROSS THE AREA. THE NORTHERN THIRD TO 40 PERCENT OF THE AREA WILL
STRUGGLE TO GET ABOVE 10 DEGREES.
TUESDAY NIGHT ON...
THE MODEL CONSENSUS HAS SLIGHT CHANCE/CHANCE POPS TUES NIGHT/WED AND
SLIGHT CHANCE POPS WED NIGHT AS THE NEXT DISTURBANCE MOVES THROUGH
THE AREA. MOISTURE WILL BE VERY LIMITED BUT SNOW/RAIN RATIOS WILL BE
HIGH. SO WHAT MOISTURE IS AVAILABLE WILL GO INTO PRODUCING A VERY
DRY SNOW. A REASONABLE GUESS ON AMOUNTS THIS FAR OUT WOULD BE AROUND
AN INCH WITH PERHAPS A BIT MORE ACROSS THE NORTHERN THIRD OF THE
AREA.
THE NEXT ARCTIC HIGH BUILDS INTO THE MIDWEST THURSDAY INTO FRIDAY
RESULTING IN DRY CONDITIONS BUT TEMPERATURES WELL BELOW NORMAL. THE
MODEL CONSENSUS DEVELOPS WARMER RETURN FLOW FRIDAY NIGHT INTO
SATURDAY WITH DRY CONDITIONS AND BUT TEMPERATURES WILL REMAIN BELOW
NORMAL.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING) ISSUED
AT 1116 PM CST SAT DEC 21 2013
IFR CONDITIONS TO LIFR CONDITIONS WILL PRECEDE A LARGE WINTER
STORM OVERNIGHT AND SUNDAY IN EASTERN IOWA AND ILLINOIS. NORTHEAST
WINDS WILL BECOME NORTHWEST BY LATE TONIGHT...AND CONTINUE TO BE
15 TO 20 KTS...GUSTING TO MID 20S AT TIMES. CIGS OF 100 FT TO 800
FT WILL BE COMMON THROUGH SUNDAY AFTERNOON MAINLY MODERATE TO
HEAVY SNOW...VISIBILITIES DOWN TO 1/4 OR LESS AT TIMES...OVERNIGHT
IN ALL LOCATIONS EXPECT POSSIBLY BRL. SNOW WILL END BY MID MORNING
SUNDAY...BUT FOLLOWING THIS TIME...BLOWING AND DRIFTING SNOW CAN
BE EXPECTED TO CONTINUE TO BRING IFR CONDITIONS TO ALL TERMINALS
THROUGH SUNDAY AFTERNOON. THIS IS A VERY POOR FLYING
FORECAST...WITH SHORT TERM ICING AT TERMINALS FOLLOWED BY HEAVY
SNOW.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR BENTON-BUCHANAN-
CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE-HENRY IA-IOWA-
JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-LINN-LOUISA-
MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR BUREAU-CARROLL-
HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-MERCER-
PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.
MO...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR CLARK-SCOTLAND.
&&
$$
UPDATE...ERVIN
SHORT TERM...DMD
LONG TERM...08
AVIATION...ERVIN
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
359 AM EST SUN DEC 22 2013
.SYNOPSIS...
LOW PRESSURE OVER INDIANA WILL TRACK NORTHEAST TODAY...REACHING NEW
ENGLAND MONDAY. THE ASSOCIATED COLD FRONT WILL MOVE INTO THE MID-
ATLANTIC REGION TONIGHT...BECOMING STATIONARY ACROSS THE REGION MONDAY.
HIGH PRESSURE WILL BUILD INTO THE AREA TUESDAY THROUGH THURSDAY.
&&
.NEAR TERM /THROUGH TODAY/...
SEVERE THUNDERSTORM WATCH 590 IN EFFECT UNTIL 15Z FOR THE ENTIRE CWA
EXCEPT FOR LOWER SRN MD.
AS OF 0830Z...AMPLIFIED WAVE PATTERN WITH DEEP TROUGH OVER THE HIGH
PLAINS AND A BERMUDA HIGH. 988 MB SFC LOW OVER WRN OH AND TRACKING
NE. QLCS QUICKLY APPROACHING THE ALLEGHENY FRONT FROM THE WEST.
SYSTEM HAS A HISTORY OF 60 TO 65 MPH GUSTS. VERY DYNAMIC
SYSTEM...HIGH SHEAR AND LOW CAPE. JUST BECAUSE THERE IS LITTLE IF
ANY LIGHTNING DOES NOT MEAN THESE LINES ARE NOT STRONG. HOW WELL THE
LINES SURVIVE CROSSING THE ROAD BUMPS OF THE APPALACHIAN RIDGES
REMAINS TO BE SEEN. 05Z HRRR DOES BRING SOME SEMBLANCE OF A LINE
ACROSS THE METRO AREAS THROUGH THE MID MORNING. A GOOD PROXY FOR
BALT-WASH WILL BE KMRB AND KHGR WHICH SHOULD BE REACHED BETWEEN 10Z
AND 11Z. BALT-WASH CORRIDOR IS PROGGED BE IMPACTED 11Z TO 13Z.
WIND ADVISORY FOR 40 KT GUSTS ABOVE 2000 FT ON THE RIDGELINES. THIS
IS ESSENTIALLY AHEAD OF THE LINE...I.E. UNTIL 8 AM OR SO.
TODAY...THE SFC LOW SLOWLY FILLS AS IT MOVES NE TO NY STATE. THE
TRAILING COLD FRONT REACHES WV BY SUNSET...BUT STALLS WELL INTO
MONDAY. EXPECT A MORNING WAVE OF PRECIP...THEN A SECONDARY WAVE THIS
AFTERNOON INTO THE EVENING.
DYNAMICALLY DRIVEN TEMPERATURES TODAY...ALREADY AROUND 70F THIS
MORNING. LOW TO MID 70S AHEAD OF MAIN PRECIP POSSIBLE...PARTICULARLY
LATER THIS MORNING.
&&
.SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/...
FLOODING THREAT FROM HEAVY RAIN ALONG STALLED COLD FRONT TONIGHT
INTO MONDAY. WITH MESOSCALE FEATURES DOMINATING AT THIS TIME...NO
FLOOD WATCH. WILL NEED TO MONITOR WHERE BOUNDARIES SET UP. THE 00Z
GFS/ECMWF FAVOR AREAS SOUTHEAST OF DC FOR THE HEAVIEST RAINFALL.
UPSLOPE SNOW ON BACK SIDE OF THE SYSTEM LOOKS LIGHT FOR LATE
MONDAY...PERHAPS AN INCH OR SO ABOVE 3 KFT.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
THE NEXT 36 HRS WL FEATURE PLENTY OF WX...BEGINNING MON NGT
THINGS BEGIN TO SETTLE DOWN. FNT IS XPCTD TO BE MOVG
OFFSHORE...HIGH PRES BLDG INTO THE AREA. IT`S DFCLT TO ENVISION
SNOW IN THE FCST WHEN THE CURRENT TEMPS ARE RANGING FM 65-70...BUT
W/ COLDER AIR AND HIGH PRES STARTING TO BUILD BACK INTO THE RGN
THE SUB-1300 850-1000 THCKNS LN LOOKS TO BE MOVG E OF THE BLU RDG
AFTR MDNGT MON NGT. UPSLOPE SNOWS XPCTD TO BEGIN ON THE WRN SLOPES
OF THE HIGHLANDS AFTR MDNGT AS WELL. IF ACCUMS OCCUR IT IS LOOKING
TO BE LGT - UPR TROF WL MOVE E TO THE CST TUE AFTN...SFC HIGH PRES
IS XPCTD TO BUILD IN QUICKLY.
LOW ON NGT MOVG BACK TOWARDS LATE DEC NORMS...20S BLUE RDG AND
W....30S E. TUE HIGHS IN THE 30S BLUE RDG AND W...L40S E.
HIGH PRES SETTLES OVR THE AREA TUE NGT BRINGING CLR SKIES FOR
CHRISTMAS EVE. LOWS IN THE 20S E OF THE MTNS...MU TEENS W OF BLUE
RDG...L TEENS IN THE HIGHLANDS.
CHRISTMAS DAY STILL LOOKING NICE UNDER HIGH PRES - SUNNY SKIES W/
HIGHS IN THE 30S.
AN UPPER SHORT WV TROF LOOKS TO TRACK N OF THE AREA FRI. FOR NOW
THE DAY WL BE LEFT DRY. HIGH PRES THEN XPCTD TO RETURN FOR NEXT WKND.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
MVFR CIGS IN STRONG SLY FLOW AHEAD OF A COLD FRONT THAT APPROACHES
THIS EVENING. GUSTS TO AROUND 30 KT. LINES OF WINDY SHOWERS APPROACH
THE TERMINALS THROUGH THE MID MORNING. WILL NEED TO MONITOR THEM AS
THEY CROSS THE APPALACHIAN RIDGES. LOW CEILINGS THROUGH THE NIGHT
AND INTO MONDAY AS THE COLD FRONT STALLS OVER THE AREA.
SLOW BUT GRADUAL CLEARING BEHIND THE COLD FRONT MONDAY NIGHT WILL
LEAD TO A RISE IN CEILINGS AND IMPROVING VISIBILITY...RESULTING
IN VFR CONDITIONS. WINDS WILL SHIFT FROM SOUTH-SOUTHWEST TO
NORTHWEST AT AROUND 10 KNOTS WITH OCCASIONAL GUSTS TO 20 KNOTS.
VFR CONDS TUE THRU THU.
&&
.MARINE...
S-SWLY FLOW CONTINUES TO GUST UP TO 30 KT THROUGH AT LEAST THE
MORNING...SLOWLY DECREASING THIS AFTERNOON. EXTENDED SCA FOR WATERS
SOUTH OF SANDY PT AND MIDDLE/LOWER TIDAL POTOMAC FOR THIS EVENING.
RAIN CONTINUES INTO MONDAY WITH STALLED COLD FRONT. GUSTS WITH THE
RAIN COULD REQUIRE SPECIAL MARINE WARNINGS FOR GUSTS IN EXCESS OF 34
KT.
HIGH PRES BLDG INTO THE AREA MON NGT AND TUE WL LKLY LEAD TO SCA`S
FOR ALL OF THE WATERS. HIGH PRES BLDG OVR THE AREA TUE NGT THRU
THU - NO PROBS ON THE WATERS.
&&
.CLIMATE...
RECORD HIGH TEMPS SET ON SAT AT IAD...DCA...BWI...MRB. RECORD HIGH
MINS SET SAT AT IAD...DCA...AND BWI. THE BWI AND DCA MIN RECORDS
WERE 118 YRS OLD!
RECORDS HIGH TEMPS FOR TODAY AND MON:
12/22...
MIN MAX
BWI...48 (1931)......70 (1889)
DCA...49 (1923)......72 (1889)
IAD...49 (1990)......67 (1984)
12/23...(HI MIN ONLY)
BWI...59 (1990)*
DCA...57 (1990)
IAD...61 (1990)*
* = HIGHEST MIN TEMP IN DECEMBER. THE HIGHEST DECEMBER MIN TEMP
FOR THE DCA PERIOD OF RECORD WAS 59 ON DEC 5 1973.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR VAZ025>027-029-
030-036>040-503-504.
WV...WIND ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR WVZ055-501-502-
505-506.
MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR
ANZ532>534-536-537-540>543.
SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS EVENING FOR ANZ530-
531-535-538-539.
&&
$$
PRODUCTS...BAJ/WOODY!
AREA FORECAST DISCUSSION
NWS GAYLORD MI
202 AM EST SUN DEC 22 2013
.SYNOPSIS...
ISSUED AT 411 PM EST SAT DEC 21 2013
AN AREA OF LOW PRESSURE WILL LIFT THROUGH THE OHIO VALLEY AND INTO
SOUTHERN ONTARIO TONIGHT THROUGH SUNDAY. THIS WILL GENERATE PERIODS
OF SNOW ACROSS NORTHERN MICHIGAN...WITH SOME MIXED PRECIPITATION IN
MID AND SOUTHERN MICHIGAN THROUGH SUNDAY. COLD AIR WILL FILTER
BACK INTO THE GREAT LAKES MONDAY AND TUESDAY AS THIS SYSTEM EXITS
EAST...GENERATING SOME LAKE EFFECT SNOW ACROSS PARTS OF NORTHERN
MICHIGAN.
CHANCES FOR SNOW CONTINUES CHRISTMAS DAY THROUGH THE END OF THE WORK
WEEK...AS A SERIES OF WEAK CLIPPERS PUSH ACROSS THE GREAT LAKES.
&&
.UPDATE...
ISSUED AT 158 AM EST SUN DEC 22 2013
WEATHER EVENT STARTING TO UNFOLD. INITIAL NRN EDGE OF OF
PRECIPITATION SHIELD FROM SFC LOW MOVING THROUGH NORTH OF THE OHIO
VALLEY...HAS WORKED INTO THE SE HALF OF THE CWA. THIS SNOW WAS
ALREADY LIGHT...AND WILL LIGHTEN MORE AND MAYBE EVEN STOP FOR
JUST A BIT OVER THE NEXT HOUR OR SO. THEN...NEXT ROUND OF
DEVELOPING PRECIPITATION FROM SW LOWER AND SRN LAKE MICHIGAN RACE
IN 09-12Z. THE LIGHT NATURE OF THE SNOW IS DUE IN PART TO JUST
WEAK DEEP LAYER FORCING ATTM...AND POSSIBLY LESS LOW LEVEL
WARM/MOIST ADVECTION...STOLEN TO SOME DEGREE FROM EARLIER
CONVECTIVE LINE NOW MOVING INTO THE APPALACHIANS.
THE MAIN SHOW IS STILL SET FOR LATER TONIGHT INTO TOMORROW
MORNING. STRONGEST FORCING FROM SHORTWAVE LIFTING INTO THE KANSAS
CITY AREA...NOW STARTING TO LIFT INTO NW IL/SRN WI...AND SNOW WAS
DEVELOPING/EXPANDING. WHILE LATEST HI RES HRRR IS CURIOUSLY
SUGGESTING A LULL 11-15Z...THAT IS WHEN THE STRONGEST SHORTWAVE
FORCING/DEFORMATION WILL START TO MOVE IN. THIS IS WHEN IT
SHOULD BE DEVELOPING THE MAIN SNOW OVERHEAD. HARDEST FALLING SNOW
WILL BE 13Z-18Z IN NRN LOWER...AND 16-20Z ACROSS EASTERN UPPER.
FCST SOUNDINGS STILL DO SUGGEST A MIX WITH SLEET MAYBE NEAR THE
SAG BAY THROUGH 13Z...BUT THEN THINGS SHOULD BE ALL SNOW
EVERYWHERE FOR TODAY. FORECAST IN GOOD SHAPE...SNOW AMOUNTS AND
QPF LOOK GOOD. NO REAL SIGNIFICANT UPDATES. WILL BE SENDING OUT
SPSAPX OVERNIGHT WHEN HEAVIER SNOWS START TO MOVE IN.
UPDATE ISSUED AT 1011 PM EST SAT DEC 21 2013
SNOW HAS BACKED UP INTO ARENAC AND PARTS OF GLADWIN AND IOSCO
COUNTIES. THE NEXT NORTHWARD PUSH IS STARTING TO TAKE SHAPE OVER
THE SOUTH HALF OF LAKE MI. THAT SAID...MOST GRID FINE-TUNING TO
THIS POINT INVOLVES SLOWING THE NORTHWARD PROGRESS OF SNOW INTO
NORTHERN MI. ONSET HAS BEEN SLOWED BY A COUPLE OF HOURS IN MUCH OF
NORTHERN MI...WITH PRECIP HELD BACK BY DRY LOW/MID-LEVEL AIR
FEEDING INTO THE REGION FROM THE NE (NOTING THAT EASTERN UPPER MI
IS CLEAR BELOW CIRRUS LEVEL).
TO COUNTER THAT...SNOW INTENSITY MAY BE MORE IMPRESSIVE LATE TONIGHT
(AFTER 08Z) THAN EARLIER PROGGED. STORM-RELATIVE EASTERLY FLOW IN
THE COLD CONVEYOR BELT REALLY TAKES OFF AFTER 06Z...THANKS TO
TIGHTENING PRESSURE/HEIGHT GRADIENTS OVER LAKE HURON AND SOUTHERN
ONTARIO...AND A SLIGHT ACCELERATION IN STORM MOTION TO THE NE.
DESPITE THE SLOWER ONSET...AM CONCERNED THAT QPF/SNOW AMOUNTS MAY
BE A BIT LOW IN PARTS OF N CENTRAL/NE LOWER...ESPECIALLY FROM
GRAYLING TO APN. COULD STAND TO ADD ANOTHER INCH OF ACCUMS TO
THESE AREAS FOR THE OVERNIGHT (THOUGH ELIMINATING THE SAME FROM
THE DAYTIME SUNDAY FORECAST...NOT CHANGING OVERALL SNOW AMOUNTS
MUCH).
NO CHANGES TO OUR PRESENT HEADLINES. NEW WSW WILL LIKELY BE ISSUED
BETWEEN 11 PM AND MIDNIGHT TO FRESHEN TIMING.
UPDATE ISSUED AT 717 PM EST SAT DEC 21 2013
998MB LOW PRESSURE IN THE MID MS VALLEY THIS EVENING. A WARM
FRONT AHEAD OF THE LOW HAS LIFTED PAST LOUISVILLE...CINCY AND
COLUMBUS. WARM CONVEYOR BELT ARCS FROM SW INDIANA TOWARD LAKES
ERIE AND ONTARIO. THE COLD CONVEYOR BELT POKES SW-WARD FROM
SOUTHERN LOWER MI TO NORTHERN MIZZOU...AND IT IS THIS PART OF THE
STORM THAT WILL LIFT NORTHWARD INTO NORTHERN MI AS THE SURFACE LOW
MOVES NE. SNOW WILL DEVELOP IN FAR SE SECTIONS LATE THIS
EVENING...AND EXPAND NORTHWARD OVERNIGHT. SMALL ADJUSTMENTS TO
PRECIP TIMING...NO MAJOR CHANGES NEEDED.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 411 PM EST SAT DEC 21 2013
INVERTED SFC TROUGH STRETCHES FROM THE WESTERN GULF UP THROUGH
NEW ENGLAND WITH WIDESPREAD PRECIP UNDERWAY ALONG THE CONVERGENCE
AXIS. STRONG SHORT WAVE MOVING ACROSS NRN TEXAS AND ABOUT TO SWING
UP THROUGH THE CENTRAL PLAINS AND INTO THE MIDWEST TONIGHT...THEN
UP THROUGH LOWER MICHIGAN DURING THE DAY SUNDAY. SFC LOW ON TRACK
TO SPIN UP ALONG THE EXISTING BAROCLINIC ZONE AND ADVANCE UP
THROUGH NRN OHIO/FAR SE LOWER MICHIGAN EARLY SUNDAY MORNING BEFORE
KICKING INTO THE EASTERN GREAT LAKES THROUGH THE DAY. ONGOING WARM
CONVEYOR PRECIP TO OUR SOUTH WILL INITIALLY PUSH UP INTO PARTS OF
NRN LOWER MICHIGAN LATER TONIGHT BEFORE GETTING PINCHED OFF AND
KICKED INTO THE EASTERN LAKES SUNDAY. HOWEVER...HEAVIER WRAP
AROUND/DEFORMATION SNOW ON THE BACKSIDE OF THE DEPARTING LOW IS
OUR BIGGEST CONCERN THROUGH THE DAY SUNDAY. PERIOD OF HEAVIEST
SNOW LOOKING TO OCCUR BETWEEN 15Z AND 21Z AS THE MID LEVEL SHORT
WAVE SWINGS UP THROUGH LOWER MICHIGAN.
VERY LITTLE HAS CHANGED WITH THE ABOVE SCENARIO AMONGST GUIDANCE
SOLUTIONS OVER THE LAST DAY...AND EVEN THE NAM SOLUTION (WHICH HAS
HAD THE FURTHEST NORTHERN TRACK) HAS ADJUSTED BACK SOUTH WITH ITS
18Z RUN. SO ALL GUIDANCE SOURCES CONTINUE TO GIVE NRN LOWER
MICHIGAN A MAINLY SNOW...WITH ONLY AN OUTSIDE CHANCE OF SOME
SLEET OVER THE FAR SE COUNTIES TOWARD SAGINAW BAY LATER TONIGHT.
CONSENSUS QPF FORECAST DRAGS HEAVIEST QPF BULLSEYE RIGHT UP ACROSS
NRN LOWER MICHIGAN LATE TONIGHT AND THROUGH THE DAY SUNDAY...POSSIBLY
SKIMMING FAR EASTERN UPPER MICHIGAN WITH SOME HEAVIER SNOW ON SUNDAY.
AS FAR AS SNOW AMOUNTS GO...BASICALLY HAVE A 2 PERIOD (TONIGHT AND
TOMORROW) COMBINED TOTAL OF 0.4 TO 0.6 INCHES LIQUID OVER NRN
LOWER MICHIGAN...0.2 TO 0.4 INCHES IN EASTERN UPPER MICHIGAN. SNOW
ACCUMULATIONS WILL OF COURSE BE DEPENDENT ON JUST WHAT SNOW:WATER
RATIOS ARE REALIZED. HAVE <10:1 RATIOS OVER THE S/SE COUNTIES AND
10-15:1 FOR NRN HALF OF THE CWA...YIELDING A NICE 4 TO 7 INCHES
SWEET SPOT CENTERED UP THROUGH NRN LOWER MICHIGAN. NOT MUCH
DIFFERENT WITH WHAT WE HAVE BEEN FORECASTING FOR THE LAST DAY OR
TWO. PLAN NO CHANGES TO THE CURRENT WINTER WEATHER ADVISORIES.
HAVE ALREADY ADDED EASTERN UPPER MICHIGAN INTO AN ADVISORY FOR
SOME BEEFIER SNOWFALL OVER THE EASTERN PART OF THOSE COUNTIES.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 411 PM EST SAT DEC 21 2013
LET THE COLD AND SNOW CONTINUE! REALLY NO BIG SIGNS OF ANY BREAK
FROM THE ONGOING STRETCH OF COLD/SNOWY WEATHER THE NEXT 7 DAYS...
WITH PERSISTENT GULF OF ALASKA RIDGING FAVORING DOWNSTREAM TROUGH
RENEWAL THROUGH THE CENTRAL AND EASTERN PARTS OF THE COUNTRY. THAT
WILL KEEP THE COLD AIR FLOWING OUT OF CANADA...WITH A COUPLE
REINFORCING SHOTS OF CHILLY WEATHER EXPECTED AS STRONGER UPPER
WAVES/CLIPPER SYSTEMS TRAVERSE THE NORTHERN LAKES. GUIDANCE TRENDS
THE PAST FEW DAYS HAVE INCREASED CONFIDENCE ON THE TIMING OF SUCH
FEATURES...WITH ONE EXPECTED TO ARRIVE ON CHRISTMAS DAY ITSELF...AND
ANOTHER ONE THE DAY AFTER...SANDWICHED IN BETWEEN MORE TYPICAL LAKE
EFFECT CONDITIONS BOTH EARLY AND LATE IN THE HOLIDAY WEEK. ALL THE
WHILE...TEMPERATURES THROUGH MUCH OF THE WEEK LOOK TO REMAIN WELL
BELOW NORMAL...PARTICULARLY MONDAY INTO TUESDAY.
STARTING THIS WHOLE THING OFF...THE LAST VESTIGES OF HEAVIER SNOW
SHOULD BE EXITING THE REGION BEFORE 00Z...AS THE STRONGER SOUTHERN
STREAM WAVE SHEARS OUT INTO ONTARIO AND DYNAMIC FORCING GOES TO
ZERO. THAT WILL LEAVE NORTHERN MICHIGAN IN A RATHER NEBULOUS REGIME
SUNDAY NIGHT INTO PARTS OF MONDAY...AS THE PRESSURE GRADIENT WEAKENS
CONSIDERABLY WHILE A STRONGER NORTHERN STREAM WAVE CARVES OUT OVER
THE WESTERN LAKES. MEAN NORTHERLY FLOW IN THE WAKE OF THE INITIAL
DEPARTING SYSTEM SHOULD DRAW IN SOME QUITE CHILLY BUT SHALLOW ARCTIC
AIR RIGHT ON THROUGH THE DAY ON MONDAY...INTERACTING WITH THE BAGGY
PRESSURE GRADIENT TO PERHAPS PRODUCE A COUPLE OF MESOSCALE LAKE
VORTICES...NONE OF WHICH ARE HIGH CONFIDENCE AT THIS POINT.
HOWEVER...THERE HAVE BEEN PERSISTENT HINTS OF A STRONGER CONVERGENCE
BAND TAKING SHAPE DOWNSTATE WHERE THE LOW LEVEL CYCLONIC FLOW LOOKS
TO REMAIN SHARPEST...ALL WHILE DRIER SUB-850MB AIR ADVECTS SOUTHWARD
THROUGH NORTHERN MICHIGAN. HONESTLY...JUST A VERY LOW CONFIDENCE
FORECAST FOR HOW THINGS WILL ULTIMATELY PLAY OUT...BUT DOES LOOK
LIKE THERE COULD BE SOME PESKY LINGERING LIGHT SNOWS RIGHT ON
THROUGH SUNDAY NIGHT AS THE COLUMN REMAINS NEARLY SATURATED...WITH
PERHAPS EVEN A LITTLE FLUFF TO THE SNOW WITH AN EVER-DEEPENING DGZ.
A STRONGER SOUTHERN MID-LAKE MICHIGAN CONVERGENCE BAND SHOULD GET
TURNED ASHORE INTO MONDAY AFTERNOON/EVENING WITH THE APPROACH OF THE
STRONGER SHORTWAVE ALOFT...BUT THE SETUP FOR NORTHERN MICHIGAN LOOKS
MUCH LESS IMPRESSIVE...WITH MEAN LOW LEVEL NORTHERLY FLOW FAVORING
SNOW SHOWER COVERAGE ONLY NEAR THE LAKESHORES...AS THE LOW LEVELS
DRY EVEN FURTHER. IN FACT...THAT SETUP MAY EVEN LEAD TO SOME
CLEARING LATER MONDAY NIGHT INTO TUESDAY FOR INLAND AREAS...WITH
TUESDAY/CHRISTMAS EVE LOOKING DOWNRIGHT COLD AS SHALLOW ARCTIC AIR
RESIDES OVERHEAD. SHOULD SEE HIGHS NO BETTER THAN THE MID TEENS FOR
MOST AREAS...WITH SOME SPOTS (HIGHER TERRAIN/EASTERN UPPER) MORE
THAN LIKELY STRUGGLING THROUGH THE UPPER SINGLE DIGITS.
CHRISTMAS DAY LOOKING A LITTLE MORE SNOWY FOR MOST AREAS...WITH
CONTINUED HINTS THAT ANOTHER DECENT NORTHERN STREAM WAVE WILL DROP
INTO THE AREA. AT THE MOMENT...GUIDANCE IS PEGGING A MODERATE SHOT
OF LOW/MID LEVEL WARM ADVECTION ASCENT...SUFFICIENT TO BRING A ROUND
OF SYNOPTIC SNOW TO MOST OF NORTHERN MICHIGAN. A VERY PRELIMINARY
ACCUMULATION GUESS WOULD BE A QUICK INCH OR TWO BASED ON THE
FAST-HITTING NATURE OF THE SYSTEM...BUT OF COURSE LOTS CAN CHANGE.
THE EXCEPTION SHOULD BE SOUTHWEST FLOW AREAS WITH A QUITE COLD
PRE-SYSTEM AIRMASS IN PLACE...AND RATHER STRONG SUB-800MB SOUTHWEST
FLOW PROGGED. DURATION OF THAT FLOW IS ALSO MODELED AROUND 18
HOURS...SO NOT IMPOSSIBLE SOME SPOTS COULD SEE SOME HEAVY TOTALS.
CONFIDENCE A LITTLE LOWER WITH ANOTHER SYSTEM EXPECTED ON THURSDAY...
AS A STRONGER NORTHERN STREAM WAVE DROPS INTO GREAT LAKES. ECMWF HAS
FOR SEVERAL DAYS BEEN THE STRONGEST OUTLIER...WHICH WOULD SUPPORT A
MODEST LAKE ENHANCEMENT EVENT ACROSS PARTS OF THE AREA. GFS HAS BEEN
TRENDING THIS WAY SLOWLY...WITH WHAT LOOKS (ON PAPER AT LEAST) LIKE
A FAIRLY GOOD SETUP FOR LAKE SNOWS AS STRONG HIGH PRESSURE FOLDS
AROUND THE GREAT LAKES...WHILE AMBIENT THERMAL TROUGHING HANGS FIRM
OVER THE WATERS...FAVORING A TIGHT CYCLONIC CURVATURE TO THE LOW
LEVEL WIND FIELDS. AIRMASS ON ALL GUIDANCE IS PLENTY COLD...WITH H8
TEMPS AVERAGING -17C...SO SOMETHING TO WATCH CLOSELY AS THERE IS
SOME SNEAKY POTENTIAL WITH THIS ONE. OTHERWISE...LOOKS LIKE THINGS
MAY GET A LITTLE MORE QUIET AND PERHAPS SLIGHTLY WARMER TOWARD NEXT
WEEKEND AS A LARGE EXPANSE OF HIGH PRESSURE PROGGED BY MOST GUIDANCE
TO BUILD OVER MUCH OF THE EASTERN HALF OF THE CONUS.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1152 PM EST SAT DEC 21 2013
SNOW ARRIVES OVERNIGHT...WITH IFR CONDITIONS LASTING THRU EARLY
SUNDAY AFTERNOON.
LOW PRESSURE BETWEEN INDY AND LOUISVILLE WILL MOVE NE...REACHING
TOLEDO BY SUNDAY MORNING...AND NE NY STATE BY EVENING. SNOW ALONG
THE N AND NW FLANK OF THE LOW WILL ARRIVE JUST AFTER 06Z TONIGHT.
VSBYS/CIGS WILL QUICKLY LOWER TO IFR...AND WILL PROBABLY BE LIFR
AT TIMES UP UNTIL SNOW DIMINISHES TOWARD 18Z. LIGHTER SHSN WILL
LINGER INTO SUNDAY EVENING.
NE-ERLY WINDS THRU MOST OF THE FORECAST...BACKING A BIT MORE
NORTHERLY SUNDAY AFTERNOON. GUSTY AT APN...WITH SOME BLSN ISSUES.
WIND BECOMING LIGHT SUNDAY NIGHT.
&&
.MARINE...
ISSUED AT 411 PM EST SAT DEC 21 2013
EASTERLY WINDS WILL INCREASE ACROSS NORTHERN MICHIGAN TONIGHT AND
PERSIST THROUGH SUNDAY AS A WINTER STORM SYSTEM TRACKS THROUGH THE
LOWER GREAT LAKES. GUSTS OF 20 TO 30 KNOTS WILL BE MOST COMMON
ALTHOUGH FEW GUSTS REACHING GALE FORCE ON LAKE HURON ARE NOT OUT
OF THE QUESTION. WINDS BACK NORTHERLY AND DIMINISH LATER SUNDAY
AND SUNDAY NIGHT AS THE LOW TRACKS INTO THE EASTERN GREAT LAKES.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR
MIZ016>036-041-042.
WINTER WEATHER ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS
EVENING FOR MIZ008-015.
LH...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LHZ345>347.
GALE WARNING UNTIL 4 PM EST THIS AFTERNOON FOR LHZ348-349.
LM...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LMZ323-341-
342-344>346.
LS...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LSZ321-322.
&&
$$
UPDATE...SD
SYNOPSIS...KB
SHORT TERM...BA
LONG TERM...DL
AVIATION...JZ
MARINE...BA
AREA FORECAST DISCUSSION
NWS DULUTH MN
1142 PM CST SAT DEC 21 2013
.UPDATE...
ISSUED AT 904 PM CST SAT DEC 21 2013
LIGHT SNOW OR FLURRIES CONTINUED TO FALL OVER MUCH OF NORTHEAST
MINNESOTA THIS EVENING...WITH A STRONGER LAKE SNOW BAND NOW
EVIDENT JUST EAST OF THE TWIN PORTS MOVING WEST. WE DON`T PLAN ON
MAKING ANY CHANGES TO THE LAKE SNOW ADVISORY ALONG THE SOUTH SHORE
AT THIS TIME. CONSIDERABLE SHEAR EXISTS IN THE SURFACE TO 850MB
LAYER...WITH SURFACE/925MB WINDS NORTH TO NORTHEAST...AND THE
850MB FLOW EASTERLY. THIS IS NOT OUR TYPICAL SET UP FOR LES AND AT
THIS POINT...THE PLUMES ARE DOMINATED BY THE 850MB FLOW.
SIGNIFICANT SNOWFALL STILL LOOKS ON TRACK FOR THE SOUTH
SHORE...AND LATER SHIFTS MAY NEED TO UPGRADE PORTIONS OF THE
ADVISORY TO A WARNING.
WE ARE ALSO SEEING THE AFFECTS OF THE NORTHERN STREAM WAVE WITH THE
INVERTED TROUGH SHARPENING AND PRESSURE RISE MINIMUM OR SOME WEAK
FALLS OCCURRING ALONG THE INVERTED TROUGH. WEAK RETURNS ARE ALSO
EVIDENT ON AREA RADARS IN LINE WITH THE NAM. AS THIS LARGER SCALE
LIFT INCREASES OVERNIGHT...WE EXPECT LIGHT SNOW TO INCREASE IN
COVERAGE ACROSS THE REGION...AND FOR THE LAKE SNOW BANDS TO
INCREASE AS WELL. WE WILL CONTINUE TO MONITOR THE LATEST DATA AND
MAY HAVE TO CONSIDER AN ADVISORY FOR THE TWIN PORTS/COASTAL
LAKE/CARLTON COUNTY AREAS INTO AT LEAST SUNDAY OR SUNDAY EVENING
AS WE WILL BE UNDER THE INVERTED TROUGH AND THE EASTERLY 850MB
FLOW. SNOWFALL AMOUNTS SO FAR HAVE BEEN LIGHT...WITH
LUTSEN/SILVER BAY REPORTING AN INCH AS OF LATE AFTERNOON...AND
DULUTH ONLY A TENTH OR TWO AS OF MID EVENING.
&&
.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 330 PM CST SAT DEC 21 2013
AT 330 PM...IT WAS FAIRLY QUIET ACROSS THE NORTHLAND. THERE
CONTINUED TO BE FLURRIES AND ISOLATED SNOW SHOWERS FOR MOST AREAS.
THE EXCEPTION WAS ALONG THE NORTH SHORE OF LAKE SUPERIOR...WHERE
AN INCH OF SNOW FELL THIS AFTERNOON IN COASTAL LAKE AND COOK
COUNTIES. TEMPERATURES RANGED FROM THE SINGLE DIGITS AT
INTERNATIONAL FALLS TO THE 20S IN NORTHWESTERN WISCONSIN.
THE HIGH RESOLUTION MODEL DATA INDICATES THAT THERE WILL BE
PERIODS OF LAKE EFFECT SNOW CONTINUING ACROSS WESTERN LAKE
SUPERIOR TONIGHT. THE HRRR AND WRF INDICATE A CONVERGENT BAND OF
SNOW ACROSS THE WESTERN PORTION OF THE LAKE...WITH SEVERAL WAVES
IN THE LINE. THIS WILL RESULT IN LOCAL SWIRLS AND CONSIDERABLE
VARIABILITY TO THE LAKE EFFECT OVERNIGHT. STRONG NORTHEAST WINDS
AT ROCK OF AGES CONTINUED ON ONE SIDE OF THIS BAND...WITH GUSTY
SOUTHERLY WINDS AT DEVILS ISLAND ON THE OTHER SIDE.
WINDS WILL OVERWHELMINGLY BECOME NORTHEAST TO NORTH OVERNIGHT AND
ON SUNDAY...WHILE THE OTHER SYSTEM MOVES IN FROM THE WEST. THE
RESULT WILL BE A PHASING OF THE MOISTURE ACROSS THE WESTERN GREAT
LAKES. OVERALL LOOKING FOR AN INCH OR TWO FOR MUCH OF THE AREA
TONIGHT...AND ANOTHER INCH OR TWO ON SUNDAY.
THE EXCEPTION WILL BE ACROSS THE SOUTH SHORE OF LAKE SUPERIOR. WE
COULD HAVE HANDLED THIS EVENT IN A COUPLE WAYS REGARDING HEADLINES
BUT AFTER EXTENSIVE DISCUSSION...WE DECIDED TO ISSUE A LAKE EFFECT
SNOW ADVISORY FOR THE PERIOD TONIGHT THROUGH MONDAY...RATHER THAN
HAVING A LARGE LAKE EFFECT SNOW WARNING OUT FOR 5 PERIODS...WITH
GENERALLY ADVISORY TYPE SNOW FOR MOST OF THE PERIODS. THINK THERE
IS A FAIR CHANCE WE MAY NEED TO UPGRADE TO A WARNING FOR MONDAY.
BUT FOR TONIGHT AND SUNDAY...WE ARE LOOKING AT TRANSITIONAL LAKE
EFFECT SNOWFALL BANDS...SWIRLS AND CONVERGENCE BANDS...AND THE
RESULT SHOULD BE WIDESPREAD ADVISORY TYPE SNOW.
WE ALSO COULD HAVE ISSUED THE ADVISORY FOR TONIGHT THROUGH SUNDAY
NIGHT...AND MAINTAINED THE WATCH FOR MONDAY...BUT FOR SIMPLICITY
SAKE...DECIDED TO HOLD OFF ON THAT FOR NOW. THE MAIN FOCUS FOR A
POTENTIAL WARNING ON MONDAY WOULD BE THE GOGEBIC RANGE. WE DO
AGREE THAT ADDED UP OVER 4-5 PERIODS...THE AMOUNTS COULD BE
IMPRESSIVE...SOME ON THE ORDER OF A FOOT OR MORE IN THE GOGEBIC
RANGE.
.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 345 PM CST SAT DEC 21 2013
FIRST CONCERN IN EXTENDED IS ON LONG DURATION LAKE EFFECT SNOW THAT
WILL PERSIST THROUGH MONDAY EVENING. THE 12Z RUNS OF THE
GFS/ECM/NAM ARE IN AGREEMENT THAT THE H85-H50 TROUGH AXIS PASSES
OVER WRN LAKE SUPERIOR DURING THE DAY MONDAY...BRINGING A STRONG
PUSH OF CAA WITH H85 TEMPS FALLING INTO THE NEGATIVE 20S AND
BOUNDARY LAYER WINDS BACKING OUT OF THE NORTH THEN NORTHWEST.
ALTHOUGH CONDITIONS REMAIN FAVORABLE FOR A FEW INCHES OF LIGHT SNOW
ALONG THE SOUTH SHORE OF LAKE SUPERIOR SUN NIGHT...LAPSE
RATES/INVERSION HTS SIGNIFICANTLY INCREASE MONDAY DUE TO THE ARRIVAL
OF THE COLD AIR. HAVE INCREASED QPF/SN AMOUNTS MONDAY TO ACCOUNT
FOR THE HIGHER INSTABILITY.
FOCUS TURNS TO ELONGATED VORT MAX THAT DROPS OUT OF CANADA AND
ACROSS THE NRN PLAINS TUESDAY/WEDNESDAY. LATEST ECM/GFS BOTH
SUGGEST THE DIGGING WAVE...WITH SFC REFLECTION COLD FRONT...SWEEPS
ACROSS THE NORTHLAND DURING THE CHRISTMAS HOLIDAY. CURRENT TIMING
WOULD FAVOR A FEW INCHES OF SNOW OVER MUCH OF THE REGION TUESDAY
NIGHT. HOWEVER...IF TIMING SLOWS...ITS POSSIBLE THE COLD FRONT/LIGHT
SNOW HOLD OFF UNTIL CHRISTMAS DAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1141 PM CST SAT DEC 21 2013
WIDESPREAD MVFR CEILINGS...WITH SOME LOCALIZED IFR...COVERED MUCH
OF THE REGION LATE THIS EVENING. SNOW CONTINUED AROUND LAKE
SUPERIOR...WITH SOME FLURRIES ELSEWHERE. A NORTHERN STREAM
SHORTWAVE WILL CAUSE AN INVERTED TROUGH TO STRENGTHEN ACROSS THE
REGION AND CAUSE LIGHT SNOW TO EXPAND ACROSS INLAND AREAS OF THE
NORTHLAND...WITH THE LAKE EFFECT SNOW CONTINUING AROUND THE LAKE.
MVFR AND SOME IFR VSBYS WILL BECOME MORE WIDESPREAD AS THE NIGHT
PROGRESSES...LASTING THROUGH MOST OF SUNDAY INTO THE EARLY EVENING
HOURS.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 8 13 -8 1 / 90 90 70 20
INL -9 2 -20 -5 / 40 50 20 10
BRD 4 11 -13 -2 / 70 90 50 10
HYR 11 21 1 6 / 60 90 80 70
ASX 11 21 9 9 / 80 90 90 80
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...LAKE EFFECT SNOW ADVISORY UNTIL 6 PM CST MONDAY FOR WIZ001>004.
LS...SMALL CRAFT ADVISORY UNTIL 4 AM CST MONDAY FOR LSZ121-140>148.
&&
$$
UPDATE...MELDE
SHORT TERM...DAP
LONG TERM...GRANING
AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
132 AM EST SUN DEC 22 2013
.SYNOPSIS...
A STORM SYSTEM WILL MOVE FROM THE MISSISSIPPI RIVER VALLEY TO THE
LOWER GREAT LAKES TONIGHT AND BRING RAIN TO THE REGION. A COLD
FRONT WILL SWING THRU THE AREA BRING DRIER AND SOMEWHAT COOLER AIR
TO THE AREA SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH TODAY/...
1245 AM SUN UPDATE... WE`VE ISSUED A FRZG RAIN ADVSY FOR OUR FAR
NRN ZNS TIL 12Z. SFC/MESO-NET OBS HAVE SHOWN A STEADY DOWNWARD
TEMP/DEW PT TREND THE LAST FEW HRS...AS LOW-LVL COLD AIR CONTS TO
BLEED SWD ATTM. READINGS ARE DOWN TO 31-32F N/W OF A KPEO-KSYR-
KRME LN...AND WE SUSPECT THEY`LL STAY ABT WHERE THEY ARE THE NEXT
3-6 HRS. GIVEN RADAR COVERAGE UPSTREAM...WE FELT AN ADVSY WAS OUR
BEST BET.
TWDS DAYBREAK (10-12Z)...AS THE MAIN SFC WV APPROACHES FROM THE
SW...BLYR WAA SHOULD INCREASE...CAUSING THE LOW-LVL BAROCLINIC ZN
TO LIKELY BEGIN LIFTING NWD AGN. AS THIS OCCURS...WE SHOULD SEE
THE SHALLOW COLD AMS GET ERODED FROM S TO N...WITH -FZRA GETTING
LESS WIDESPREAD.
OUTSIDE OF MODIFICATIONS TO THE TEMP/DEW PT/WX GRIDS...WE JUST
MADE OTHER SLIGHT TWEAKS ATTM.
PREV DISC... 740 PM UPDATE...
CHALLENGING NEAR TERM FORECAST AS FRONT WAVERS NORTH AND SOUTH IN
ADVANCE OF NORTHEAST MOVING CYCLONE. AREAS NORTHWEST OF THE FRONT
ARE FLIRTING WITH TEMPERATURES IN THE LOWER 30S, WITH FREEZING
RAIN BECOMING A FACTOR.
LATEST NAM12 925MB TEMPERATURE PATTERN SEEMS TO BE VERIFYING
REASONABLY WELL, AND WE USED THIS AS OUR BASIS FOR MOVING THE FRONT
OVER THE NEXT SEVERAL HOURS. BASED ON THIS ANALYSIS, BELIEVE THERE
IS A CHANCE FOR THE COLD AIR TO POUR INTO THE NORTHWESTERN CORNER
OF STEUBEN COUNTY, UP THROUGH WESTERN SENECA COUNTY, BETWEEN 3Z
AND 8Z. THERE IS NOW A SLIGHT CHANCE FOR FREEZING RAIN FOR A SHORT
WINDOW IN THIS AREA.
THEREAFTER THE WARM AIR COMES THROUGH ON A TRUCK...DRIVEN BY
STRONG SOUTHWESTERLY FLOW, AND PUSHING SURFACE TEMPS THROUGH THE
40S AND 50S ACROSS THE REGION FOR EARLY SUNDAY MORNING.
THE OTHER PROBLEM OF THE EVENING IS OBVIOUSLY QPF. HAVE REWORKED
THE 0Z-6Z QPF GRIDS BASED ON LATEST GUIDANCE, AND STAYED PRETTY
MUCH IN LINE WITH HPC FOR 6Z-12Z. THE GFS HAS BEEN ALL OVER THE
MAP THE LAST 24 HOURS, AT ONE TIME BEING AN OUTLIER ON THE HIGH
SIDE OF QPF, AND NOW BEING ON THE LOW SIDE. ITS INCONSISTENCY
GIVES ME LITTLE CONFIDENCE, SO I WEIGHTED IT LOW COMPARED TO THE
NEW NAM12, HRRR, AND RAP PROJECTIONS. IN TOTAL, THE NET EFFECT WAS
A DECREASE IN STORM TOTAL QPF OF ABOUT 0.15 TO 0.30 INCHES. THIS
LOOKS PRETTY GOOD COMPARED WITH UPSTREAM RADAR DEPICTION.
WILL CONTINUE TO ASSESS THE EARLY SUNDAY MORNING QPF SCENARIO.
EARLIER DISC... 3 PM UPDATE... COMPLEX SCENARIO FOR THE FCST AS
VERY WRM AIR STREAMS NEWRD TNGT LOADED WITH MOISTURE.
MEANWHILE...CONFLUENT UPR FLOW TRIES TO BLD THE LL COLD OVER NRN
NY WITH SFC RDGG. SOME OF THAT COLDER AIR ALREADY HAS AFFECTED THE
FAR NRN ZONES AND SYR DROPPED 7F IN THE PAST HR. LOOKS LIKE A
CLOSE CALL BUT THAT THE BLO FRZG AIR WILL REMAIN JUST NORTH OF THE
FINGER LAKES ZONES THRU TNGT...BEFORE BEING PUSHED NWRD.
OTR ISSUE IS THE HEAVY RAIN AND SNOW MELT. MODELS CONT TO KEEP THE
AXIS OF HEAVY RAIN GNRLY NORTH OF THE SUSQ BASIN...AND JUST
TOUCHING THE FINGER LAKES. 12 HR QPF LOOS TO BE UNDER 2 INCHES BUT
WITH SNOW MELT...SOME FCST PTS WILL HIT A MINOR FLOOD STAGE
BEGINNING SUNDAY. HAVE XTNDD THE CVRG OF THE WATCH TO INCLUDE ALL
NY COUNTIES XCPT SULLIVAN...AND TWO NRN PA COUNTIES. SEE HYDRO
DISC FOR DETAILS ON THE FLOOD PTNL.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
NO REAL BRK IN THE SHRT TERM AS A GOOD SLUG OF PCPN PASSES WITH A
SFC TROF/COLD FNT ON SUNDAY. GOOD NEWS IS THAT THE PCPN WILL BE
PROGRESSIVE SO THERE WILL HOPEFULLY LTL XTRA EFFECT ON THE RVRS.
FNT STALLS AGAIN...THIS TIME EAST OF THE FCST AREA. HWVR...THERE
IS NO COLD AIR TO SPEAK OF AND AS A WV MVES UP THE MON...MSTLY
RAIN WILL FALL OVER THE ERN ZONES WITH PERHAPS SOME SNOW LATE AS
THE COLD AIR FNLY BEGINS TO ARRIVE. WLD NOT BE SURPRISED TO SEE
AND INCH OR TWO OF SNOW ON THE BACK SIDE LATE MON. WILL WORRY ABT
THAT LTR.
UPR TROF SETTLES IN WITH SOME SYNOPTIC MOISTURE AND LE SNOWS AS H8
TEMPS APRCH -20C LATE IN THE DAY. FLOW IS RATHER SHEARED EARLY
ON...BUT MAY ALIGN LATE IN THE PD INCRSG ACTIVITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
1 PM EST UPDATE...
FOLLOWED WPC GUIDANCE. GFS AND EURO ARE SIMILAR. COLDER AND DRIER
THAN NORMAL. COLD ENOUGH FOR ALL SNOW BUT AMOUNTS WILL BE MINOR.
MOSTLY IN A BROAD UPPER LEVEL TROF. LINGERING LAKE EFFECT SNOW
IN CENTRAL NY TUES NGT GETS SHUT OFF AS A LARGE SFC HIGH PRESSURE
SITS OVER THE EAST COAST WED AND WED NGT. A DIGGING SHORT WAVE
SINKS SE INTO THE AREA LATE THU AND THU NGT WITH A SFC COLD FRONT.
LAKE EFFECT BEHIND IT FRIDAY BUT LOW LEVEL FLOW SHIFTS TO THE WEST
AND HIGH PRESSURE BUILDS IN SATURDAY.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
06Z UPDATE...
A COMPLEX WEATHER FORECAST IS EXPECTED FOR THE TAF PERIOD. A WARM
FRONT IS LOCATED OVER CENTRAL NEW YORK THIS MORNING. THIS FRONT IS
EXPECTED TO REMAIN STATIONARY FOR THE NEXT COUPLE OF HOURS.AROUND
10Z...THIS FRONT WILL SLOWLY LIFT NORTH. WITH THAT BEING SAID TAF
SITES SOUTH OF THE FRONT ARE LOOKING AT VFR CONDITIONS. TAFS SITES
NORTH OF THIS FRONT ARE LOOKING AT MVFR AND IFR CIGS AND VISBYS.
CONFIDENCE IS NOT HIGH ON THE EXACT TIMING OF WHEN THE FRONT WILL
LIFT NORTH. CONFIDENCE IS LOW THAT KELM AND KBGM WILL REMAIN AT
FUEL ALTERNATE CIGS. THE CIGS AT THESE SITES MAY FALL TO AROUND
500 FT BUT CONFIDENCE IS LOW AND LEFT OUT OF TAF AS THEY WILL BE
ON THE OUTER EDGE OF THE WARM FRONT.
CIGS AT SITES KRME... KSYR... AND KITH WILL REMAIN LOW THROUGH
MID MORNING AS THE FRONT REMAINS WELL TO SOUTH. LIGHT FREEZING
RAIN IS A POSSIBILITY AT KRME AND KSYR AS COLD AIR WILL SLOWLY
FUNNEL INTO THE REGION. THE CHANCE FOR FREEZING RAIN IS EXPECTED
TO END AFTER SUNRISE AS TEMPS ARE EXPECTED TO WARM QUICKLY OVER
THE REGION. CONDITIONS MAY IMPROVE BRIEFLY LATE SUNDAY NIGHT INTO
MONDAY MORNING.
OUTLOOK...
SUN NGT-MON...RESTRICTIONS POSSIBLE FROM -SHRA/-SHSN.
TUE AND WED...VFR...WITH ISOLATED MVFR IN -SHSN EARLY.
THU...VFR.
&&
.HYDROLOGY...
9 PM UPDATE...
SEVERAL POINTS ARE FORECAST TO GET INTO MINOR FLOOD STAGE SUNDAY
OR SUNDAY NIGHT...AND LAKELAND OF NINE MILE CREEK EVEN ECLIPSING
MODERATE STAGE. MODEL CONSENSUS IS MORE DECIDEDLY NORTHWEST OF
MOST OF THE AREA FOR THE HIGHEST RAINFALL AMOUNTS...YET DEGREE OF
SNOWMELT IN LAST 12-24 HOURS HAS ALSO BEEN FASTER THAN EXPECTED.
SNOWMELT AND THE ADDITIONAL THREE-QUARTERS OF AN INCH TO INCH-
AND-A-QUARTER OF RAINFALL TONIGHT THROUGH SUNDAY FOR MOST OF THE
FLOOD WATCH AREA /MOST OF CENTRAL NEW YORK AND INTO NORTHERN TIER
PA/ WILL RESULT IN SIGNIFICANT RISES FOR RIVERS. RIVER FORECAST
CENTERS ARE CRUNCHING UPDATED FORECASTS BASED ON OBSERVED AND
EXPECTED RAINFALL ALONG WITH SNOWMELT AND CURRENT STAGES. WE
ANTICIPATE MAKING SOME WARNING DECISIONS LATER THIS EVENING FOR
SEVERAL OF OUR RIVER POINTS...JOINING LAKELAND WITH RIVER FLOOD
WARNING. STILL EXPECTING ACTION STAGE TO SOMEWHERE INTO MINOR
FLOOD STAGE FOR VAST MAJORITY OF AFFECTED RIVER POINTS. MODERATE
STAGES SHOULD BE LIMITED TO ONLY ONE OR TWO SITES. SMALL STREAM
AND STORM DRAIN TROUBLES STILL APPEAR LIKELY ACROSS THE CENTRAL NY
COUNTIES TONIGHT THROUGH SUNDAY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH THROUGH MONDAY MORNING FOR PAZ038-039.
NY...FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ009-015>018-022>025-
036-037-044>046-055>057.
FREEZING RAIN ADVISORY UNTIL 7 AM EST THIS MORNING FOR NYZ009-
015>018.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP/MLJ
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...KAH
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1253 AM EST SUN DEC 22 2013
.SYNOPSIS...
A STORM SYSTEM WILL MOVE FROM THE MISSISSIPPI RIVER VALLEY TO THE
LOWER GREAT LAKES TONIGHT AND BRING RAIN TO THE REGION. A COLD
FRONT WILL SWING THRU THE AREA BRING DRIER AND SOMEWHAT COOLER AIR
TO THE AREA SUNDAY NIGHT AND MONDAY.
&&
.NEAR TERM /THROUGH TODAY/...
1245 AM SUN UPDATE... WE`VE ISSUED A FRZG RAIN ADVSY FOR OUR FAR
NRN ZNS TIL 12Z. SFC/MESO-NET OBS HAVE SHOWN A STEADY DOWNWARD
TEMP/DEW PT TREND THE LAST FEW HRS...AS LOW-LVL COLD AIR CONTS TO
BLEED SWD ATTM. READINGS ARE DOWN TO 31-32F N/W OF A KPEO-KSYR-
KRME LN...AND WE SUSPECT THEY`LL STAY ABT WHERE THEY ARE THE NEXT
3-6 HRS. GIVEN RADAR COVERAGE UPSTREAM...WE FELT AN ADVSY WAS OUR
BEST BET.
TWDS DAYBREAK (10-12Z)...AS THE MAIN SFC WV APPROACHES FROM THE
SW...BLYR WAA SHOULD INCREASE...CAUSING THE LOW-LVL BAROCLINIC ZN
TO LIKELY BEGIN LIFTING NWD AGN. AS THIS OCCURS...WE SHOULD SEE
THE SHALLOW COLD AMS GET ERODED FROM S TO N...WITH -FZRA GETTING
LESS WIDESPREAD.
OUTSIDE OF MODIFICATIONS TO THE TEMP/DEW PT/WX GRIDS...WE JUST
MADE OTHER SLIGHT TWEAKS ATTM.
PREV DISC... 740 PM UPDATE...
CHALLENGING NEAR TERM FORECAST AS FRONT WAVERS NORTH AND SOUTH IN
ADVANCE OF NORTHEAST MOVING CYCLONE. AREAS NORTHWEST OF THE FRONT
ARE FLIRTING WITH TEMPERATURES IN THE LOWER 30S, WITH FREEZING
RAIN BECOMING A FACTOR.
LATEST NAM12 925MB TEMPERATURE PATTERN SEEMS TO BE VERIFYING
REASONABLY WELL, AND WE USED THIS AS OUR BASIS FOR MOVING THE FRONT
OVER THE NEXT SEVERAL HOURS. BASED ON THIS ANALYSIS, BELIEVE THERE
IS A CHANCE FOR THE COLD AIR TO POUR INTO THE NORTHWESTERN CORNER
OF STEUBEN COUNTY, UP THROUGH WESTERN SENECA COUNTY, BETWEEN 3Z
AND 8Z. THERE IS NOW A SLIGHT CHANCE FOR FREEZING RAIN FOR A SHORT
WINDOW IN THIS AREA.
THEREAFTER THE WARM AIR COMES THROUGH ON A TRUCK...DRIVEN BY
STRONG SOUTHWESTERLY FLOW, AND PUSHING SURFACE TEMPS THROUGH THE
40S AND 50S ACROSS THE REGION FOR EARLY SUNDAY MORNING.
THE OTHER PROBLEM OF THE EVENING IS OBVIOUSLY QPF. HAVE REWORKED
THE 0Z-6Z QPF GRIDS BASED ON LATEST GUIDANCE, AND STAYED PRETTY
MUCH IN LINE WITH HPC FOR 6Z-12Z. THE GFS HAS BEEN ALL OVER THE
MAP THE LAST 24 HOURS, AT ONE TIME BEING AN OUTLIER ON THE HIGH
SIDE OF QPF, AND NOW BEING ON THE LOW SIDE. ITS INCONSISTENCY
GIVES ME LITTLE CONFIDENCE, SO I WEIGHTED IT LOW COMPARED TO THE
NEW NAM12, HRRR, AND RAP PROJECTIONS. IN TOTAL, THE NET EFFECT WAS
A DECREASE IN STORM TOTAL QPF OF ABOUT 0.15 TO 0.30 INCHES. THIS
LOOKS PRETTY GOOD COMPARED WITH UPSTREAM RADAR DEPICTION.
WILL CONTINUE TO ASSESS THE EARLY SUNDAY MORNING QPF SCENARIO.
EARLIER DISC... 3 PM UPDATE... COMPLEX SCENARIO FOR THE FCST AS
VERY WRM AIR STREAMS NEWRD TNGT LOADED WITH MOISTURE.
MEANWHILE...CONFLUENT UPR FLOW TRIES TO BLD THE LL COLD OVER NRN
NY WITH SFC RDGG. SOME OF THAT COLDER AIR ALREADY HAS AFFECTED THE
FAR NRN ZONES AND SYR DROPPED 7F IN THE PAST HR. LOOKS LIKE A
CLOSE CALL BUT THAT THE BLO FRZG AIR WILL REMAIN JUST NORTH OF THE
FINGER LAKES ZONES THRU TNGT...BEFORE BEING PUSHED NWRD.
OTR ISSUE IS THE HEAVY RAIN AND SNOW MELT. MODELS CONT TO KEEP THE
AXIS OF HEAVY RAIN GNRLY NORTH OF THE SUSQ BASIN...AND JUST
TOUCHING THE FINGER LAKES. 12 HR QPF LOOS TO BE UNDER 2 INCHES BUT
WITH SNOW MELT...SOME FCST PTS WILL HIT A MINOR FLOOD STAGE
BEGINNING SUNDAY. HAVE XTNDD THE CVRG OF THE WATCH TO INCLUDE ALL
NY COUNTIES XCPT SULLIVAN...AND TWO NRN PA COUNTIES. SEE HYDRO
DISC FOR DETAILS ON THE FLOOD PTNL.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY/...
NO REAL BRK IN THE SHRT TERM AS A GOOD SLUG OF PCPN PASSES WITH A
SFC TROF/COLD FNT ON SUNDAY. GOOD NEWS IS THAT THE PCPN WILL BE
PROGRESSIVE SO THERE WILL HOPEFULLY LTL XTRA EFFECT ON THE RVRS.
FNT STALLS AGAIN...THIS TIME EAST OF THE FCST AREA. HWVR...THERE
IS NO COLD AIR TO SPEAK OF AND AS A WV MVES UP THE MON...MSTLY
RAIN WILL FALL OVER THE ERN ZONES WITH PERHAPS SOME SNOW LATE AS
THE COLD AIR FNLY BEGINS TO ARRIVE. WLD NOT BE SURPRISED TO SEE
AND INCH OR TWO OF SNOW ON THE BACK SIDE LATE MON. WILL WORRY ABT
THAT LTR.
UPR TROF SETTLES IN WITH SOME SYNOPTIC MOISTURE AND LE SNOWS AS H8
TEMPS APRCH -20C LATE IN THE DAY. FLOW IS RATHER SHEARED EARLY
ON...BUT MAY ALIGN LATE IN THE PD INCRSG ACTIVITY.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
1 PM EST UPDATE...
FOLLOWED WPC GUIDANCE. GFS AND EURO ARE SIMILAR. COLDER AND DRIER
THAN NORMAL. COLD ENOUGH FOR ALL SNOW BUT AMOUNTS WILL BE MINOR.
MOSTLY IN A BROAD UPPER LEVEL TROF. LINGERING LAKE EFFECT SNOW
IN CENTRAL NY TUES NGT GETS SHUT OFF AS A LARGE SFC HIGH PRESSURE
SITS OVER THE EAST COAST WED AND WED NGT. A DIGGING SHORT WAVE
SINKS SE INTO THE AREA LATE THU AND THU NGT WITH A SFC COLD FRONT.
LAKE EFFECT BEHIND IT FRIDAY BUT LOW LEVEL FLOW SHIFTS TO THE WEST
AND HIGH PRESSURE BUILDS IN SATURDAY.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
00Z UPDATE...
POOR AVIATION CONDITIONS FOR MOST LOCATIONS TONIGHT...WITH SHALLOW
SURFACE BOUNDARY SLIPPING SOUTH TO ABOUT KELM-KBGM AND THUS LOW
CIGS ALONG AND NORTH OF THERE. WAVES OF RAIN ALSO PASSING ALONG
AND NORTH OF THE FRONT. IFR OR WORSE CONDITIONS FOR ALL TERMINALS.
MEANWHILE...SOUTH OF THE FRONT...MOIST SSW WIND AT KAVP ALSO
FAVORABLE FOR DEVELOPMENT OF IFR LATER TONIGHT THROUGH MOST OF
SUNDAY. ANOTHER CONCERN IS FOR LLWS DURING EARLY MORNING HOURS AS
A 50-60 KT JET PASSES AT ABOUT 2 KFT AGL. THE JET DECREASING MID
MORNING ONWARD...BUT RESTRICTIONS FROM IFR CIGS AT LEAST
OCCASIONAL MVFR OR WORSE VIS AS WAVES OF RAIN CONTINUE. SOME
IMPROVEMENT TOWARDS THE END OF THE PERIOD AS FRONT BEGINS TO PASS
THROUGH THE AREA AND WAVE ALOFT REMOVES DEEPER MOISTURE.
OUTLOOK...
SUN NGT-MON...RESTRICTIONS POSSIBLE FROM -SHRA/-SHSN.
TUE AND WED...VFR...WITH ISOLATED MVFR IN -SHSN EARLY.
THU...VFR.
&&
.HYDROLOGY...
9 PM UPDATE...
SEVERAL POINTS ARE FORECAST TO GET INTO MINOR FLOOD STAGE SUNDAY
OR SUNDAY NIGHT...AND LAKELAND OF NINE MILE CREEK EVEN ECLIPSING
MODERATE STAGE. MODEL CONSENSUS IS MORE DECIDEDLY NORTHWEST OF
MOST OF THE AREA FOR THE HIGHEST RAINFALL AMOUNTS...YET DEGREE OF
SNOWMELT IN LAST 12-24 HOURS HAS ALSO BEEN FASTER THAN EXPECTED.
SNOWMELT AND THE ADDITIONAL THREE-QUARTERS OF AN INCH TO INCH-
AND-A-QUARTER OF RAINFALL TONIGHT THROUGH SUNDAY FOR MOST OF THE
FLOOD WATCH AREA /MOST OF CENTRAL NEW YORK AND INTO NORTHERN TIER
PA/ WILL RESULT IN SIGNIFICANT RISES FOR RIVERS. RIVER FORECAST
CENTERS ARE CRUNCHING UPDATED FORECASTS BASED ON OBSERVED AND
EXPECTED RAINFALL ALONG WITH SNOWMELT AND CURRENT STAGES. WE
ANTICIPATE MAKING SOME WARNING DECISIONS LATER THIS EVENING FOR
SEVERAL OF OUR RIVER POINTS...JOINING LAKELAND WITH RIVER FLOOD
WARNING. STILL EXPECTING ACTION STAGE TO SOMEWHERE INTO MINOR
FLOOD STAGE FOR VAST MAJORITY OF AFFECTED RIVER POINTS. MODERATE
STAGES SHOULD BE LIMITED TO ONLY ONE OR TWO SITES. SMALL STREAM
AND STORM DRAIN TROUBLES STILL APPEAR LIKELY ACROSS THE CENTRAL NY
COUNTIES TONIGHT THROUGH SUNDAY.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...FLOOD WATCH THROUGH MONDAY MORNING FOR PAZ038-039.
NY...FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ009-015>018-022>025-
036-037-044>046-055>057.
FREEZING RAIN ADVISORY UNTIL 7 AM EST THIS MORNING FOR NYZ009-
015>018.
&&
$$
SYNOPSIS...DGM
NEAR TERM...DGM/DJP/MLJ
SHORT TERM...DGM
LONG TERM...TAC
AVIATION...MDP
HYDROLOGY...
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
417 AM EST SUN DEC 22 2013
.SYNOPSIS...
LOW PRESSURE OVER NORTHERN OHIO WILL CONTINUE NORTHEAST TODAY
GIVING A KICK TO A FRONT STALLED ACROSS THE AREA. THE FRONT WILL
MOVE EAST OF THE AREA BY THE AFTERNOON ALLOWING DRIER BUT NOTABLY
COLDER AIR TO MOVE INTO THE AREA FOR MUCH OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
MODERATE TO LOCALLY HEAVY RAIN STILL OCCURRING ACROSS THE CENTRAL
AND EASTERN COUNTIES EARLY TODAY HOWEVER MODELS SHOW DRIER AIR
WRAPPING AROUND THE SYSTEM WILL MOVE IN FROM THE SOUTHWEST TODAY.
FOLLOWED SREF POP GUIDANCE STARTING WITH CATEGORICAL POPS
EARLY...DROPPING TO SLIGHT CHANCE WEST OF A KCLE TO KMFD LINE BY
15Z. BY 18Z WILL DROP FAR EASTERN COUNTIES TO CHANCE AND MUCH OF
THE REST OF THE AREA TO SLIGHT CHANCE OR LOWER. HIGHS WILL BE VERY
TRICKY TODAY AND HAVE USED THE HRRR WHICH IS ABLE TO BEST
GRAPHICALLY HANDLE MOVING THE TIGHT GRADIENT ACROSS THE AREA. IN
SHORT...EXPECT TEMPS IN THE EAST AND CENTRAL COUNTIES TO RECOVER
WITH THE MILD AIR LIFTING TO THE LAKESHORE AGAIN EARLY WHILE THE
WEST WILL REMAIN COOL. DURING THE AFTERNOON THE COOLER AIR WILL
SWEEP SOUTHEAST. WILL CONTINUE WITH THE FLOOD WATCH AS IS.
MEDIA REMIND YOUR VIEWERS AND LISTENERS NOT TO DRIVE THROUGH
FLOODED AREAS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
SHOULD GET A BIT OF A BREAK TONIGHT AS THE DRY SLOT CONTINUE
THROUGH THE AREA ALTHOUGH BY MORNING MONDAY 850MB TEMPS WILL BE
DOWN TO -7 TO -9 ON THE LAKE. WHILE THIS WILL NOT BE ENOUGH FOR
LAKE EFFECT TEMPS CONTINUE TO FALL TO -12C OR SO THROUGH THE
AFTERNOON SO WOULD EXPECT CHANCES FOR SNOW WILL INCREASE AS THE DAY
WEARS ON. WILL HAVE CHANCE POPS ACROSS THE SNOW BELT IN THE
MORNING INCREASING TO LIKELY IN THE AFTERNOON. TEMPS CONTINUE TO
DROP TO -14C BY 12Z TUESDAY WHILE THE CORE OF THE COLD AIR
(-20C) THANKFULLY DROPS ACROSS SOUTHERN AND CENTRAL OHIO. STILL
HOWEVER...-14C WILL BE LOW ENOUGH FOR LAKE EFFECT TO CONTINUE AND
IN FACT WILL HAVE CATEGORICAL POPS FOR THE OVERNIGHT MONDAY
NIGHT...DROPPING BACK TO LIKELY TUESDAY. TUESDAY NIGHT HIGH
PRESSURE AND DRIER AIR WILL MOVE QUICKLY ACROSS THE AREA
COUNTERING THE -16C TEMPS ON THE LAKE. WILL DROP POPS THROUGH
LIKELY TO CHANCE THROUGH THE NIGHT. WEDNESDAY A WARM FRONT WILL
MOVE THROUGH THE WESTERN LAKE WITH OVERRUNNING MOISTURE BRUSHING
THE AREA. AM CONCERNED THAT A LIGHT SNOW DEVELOPS SO WILL HAVE LOW
CHANCE POPS IN PLACE FOR THE DAY. WEDNESDAY NIGHT HEIGHTS DROP AS
AN UPPER LOW/TROF MOVES BACK INTO THE GREAT LAKES REGION SO WILL
CONTINUE WITH LOW CHANCE POPS.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
THURSDAY COLD FRONT MOVES THROUGH THE AREA HOWEVER THERE ARE
DIFFERENCES BETWEEN THE GFS AND ECMWF TIMING WITH THE ECMWF SLOWER
OF THE TWO. WILL FOLLOW WPC/ECMWF GUIDANCE THROUGH THE LONG TERM
PERIOD GENERALLY BRINGING BACK A SHOT AT LAKE EFFECT SNOW THURSDAY
THROUGH FRIDAY...DRYING IT OUT FOR SATURDAY AS HIGH PRESSURE
BUILDS IN.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
LOW PRESSURE IS NOW IN SOUTHWEST OHIO WITH A WARM FRONT EXTENDING
NORTHEAST THROUGH MANSFIELD TO MEADVILLE. THE LOW WILL CONTINUE TO
MOVE NORTHEAST ALONG THE FRONT AND KEEP THE RAIN GOING THROUGH
MUCH OF THE NIGHT. A LINE OF SHOWERS AND MINIMAL THUNDERSTORMS
WILL MOVE THROUGH MANSFIELD AND AKRON CANTON AREA AND WILL PRODUCE
GUSTY WINDS AS IT MOVES THROUGH THE AREA.
WE WILL CONTINUE TO SEE SOME VERY LOW CEILINGS THROUGH THE NIGHT
DUE TO THE PROXIMITY OF THE FRONTAL BOUNDARY AND LOW PRESSURE
SYSTEM. POCKETS OF HEAVY RAIN COULD DROP VISIBILITIES
CONSIDERABLY FOR BRIEF PERIODS.
EXPECTING RAIN TO FINALLY END FROM WEST TO EAST BEGINNING AROUND
12Z AS RAIN PULLS OUT OF THE REGION.
WINDS WILL BE VARIABLE THROUGH THE FORECAST PERIOD DUE TO THE LOW
PRESSURE SYSTEM TRACKING ACROSS THE AREA.
.OUTLOOK...SPOTTY NON VFR LINGERS INTO MONDAY...IMPROVING BY
TUESDAY NIGHT. BY WEDNESDAY MOSTLY VFR CONDITIONS.
&&
.MARINE...
EXPECTING A VARIABLE WIND EARLY TODAY AS LOW PRESSURE TRACKS
ACROSS THE REGION. WINDS WILL TURN SOUTHWEST 15 TO 25 KNOTS BEHIND
THE LOW HOWEVER FOR MUCH OF TODAY. HIGH PRESSURE WILL BUILD IN FOR
LATE MONDAY AND TUESDAY TURNING WINDS NORTHWEST AT 10 TO 20 KNOTS
OR SO. MID WEEK THE HIGH MOVES EAST AND WINDS TURN SOUTH TO
SOUTHWEST AT 15 TO 25 KNOTS REACHING NEAR 30 KNOTS THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...FLOOD WATCH THROUGH THIS AFTERNOON FOR OHZ003-006>014-017>023-
027>033-036>038-047-089.
PA...FLOOD WATCH THROUGH THIS AFTERNOON FOR PAZ001>003.
MARINE...NONE.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...TK
AVIATION...LOMBARDY
MARINE...TK
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
331 AM CST SUN DEC 22 2013
.SHORT TERM...
WINTER DOES NOT WANT TO LET UP FOR THE REGION WITH RENEWED CHANCES
FOR LIGHT PRECIPITATION THIS MORNING. ANOTHER TROUGH AXIS HAS STILL
TO PASS LATER THIS MORNING. WEAK Q-VECTOR CONVERGENCE IS CURRENTLY
MOVING OVER THE AREA. THIS WAS COUPLED WITH WEAK FRONTOGENETICAL
FORCING AROUND 750-700MB EDGING INTO THE SOUTHWESTERN TEXAS
PANHANDLE. MODELS WERE IN GOOD AGREEMENT SHOWING LIFT PEAKING AROUND
12Z UNDER SATURATED SOUNDINGS. ALTHOUGH...THE ONLY DIFFERENCE
BETWEEN MODEL RAP AND NAM SOUNDINGS IS A DRY NEAR SURFACE LAYER
DEPICTED BY THE NAM. THIS CAN CERTAINLY MAKE A DIFFERENCE IN SNOW
TOTALS WITH THE MORE MOIST RAP SHOWING MORE SNOWFALL.
&&
.LONG TERM...
WITH THE EXIT EAST OF THE CURRENT LONG-WAVE TROUGH MONDAY...LESSER
AMPLITUDE AND DRY NORTHWEST FLOW WILL BECOME DOMINANT THROUGH MUCH
OF THE WEEK. NEXT SHORT-WAVE UPPER TROUGH WILL SKIM BY TO THE
NORTH WEDNESDAY DRAGGING A SLIGHTLY WEAKER FRONT INTO THE AREA
EARLY WEDNESDAY THAN PREVIOUSLY ADVERTISED. FLATTER WESTERLY FLOW
APPEARS IN THE WORKS EARLY NEXT WEEKEND WITH BACKING AND INCREASING
SOUTHWEST FLOW ALOFT LATER IN THE WEEKEND...ALTHOUGH SPREAD IN THE
DEVELOPING INTER-MOUNTAIN UPPER TROUGH WILL BE ON THE RISE. THIS
PATTERN WILL YIELD MODEST WARMING MONDAY...A WEAK BACK-DOOR FRONT
WILL SLIP IN MONDAY AFTERNOON AND EVENING...WITH BETTER WARMING
AND GUSTY SOUTHWEST WINDS TUESDAY. THEN THE SLIGHT CHRISTMAS DAY
COOL-DOWN WITH SLOW WARMING THURSDAY AND FRIDAY. BIGGER BOOST IN
TEMPERATURES AND MORE GUSTY SOUTHWEST BREEZES EXPECTED SATURDAY
BEFORE NEXT COOLING THE FOLLOWING SUNDAY. MINOR CHANGES. RMCQUEEN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 37 19 46 24 55 / 10 0 0 0 0
TULIA 38 20 46 24 56 / 10 0 0 0 0
PLAINVIEW 40 21 49 25 56 / 10 0 0 0 0
LEVELLAND 42 23 51 26 56 / 10 0 0 0 0
LUBBOCK 43 23 52 26 57 / 0 0 0 0 0
DENVER CITY 44 23 52 28 55 / 10 0 0 0 0
BROWNFIELD 44 23 52 27 56 / 0 0 0 0 0
CHILDRESS 40 22 49 24 57 / 0 0 0 0 0
SPUR 45 22 53 27 57 / 0 0 0 0 0
ASPERMONT 45 23 53 29 58 / 0 0 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01/05
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
203 AM EST SUN DEC 22 2013
.SYNOPSIS...
A VERY MILD AND MOIST AIRMASS WILL REMAIN IN PLACE THROUGH THE
WEEKEND AHEAD OF AN APPROACHING COLD FRONT. SIGNIFICANT RAINFALL
IS POSSIBLE IN MANY LOCATIONS AHEAD OF THE FRONT SUNDAY INTO PARTS
OF MONDAY. THE FRONT WILL MOVE THROUGH THE AREA ON MONDAY...AND
WITH IT WILL COME AN ABRUPT END TO OUR VERY MILD WEATHER. COLDER
HIGH PRESSURE BUILDS OVER THE REGION BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 200 AM EST SUNDAY...
ADDED MORE COUNTIES TO WIND ADVISORY FOR THIS MORNING. WATCHING
CONVECTION TO THE WEST MOVING EAST. MORE CHANGES AS MORNING
PROGRESSES.
AS OF 101 AM EST SUNDAY...
ADJUSTED POPS FOR LATEST RADAR TRENDS WITH SCATTERED STORMS
FORMING AHEAD OF THE MAIN BAND OF CONVECTION TO OUR WEST IN THE
OHIO VALLEY. LOW PRESSURE WAS LOCATED IN INDIANA THIS MORNING
WITH COLD FRONT EXTENDING SOUTHWARD ACROSS WESTERN KENTUCKY AND
WESTERN TENNESSEE. COLD FRONT AND ASSOCIATED CONVECTION WILL
CONTINUE TO MOVE EAST TODAY. STRONG SOUTHERN WINDS ADVECTING
PLENTY OF MOISTURE INTO OUR REGION. WIND ADVISORIES REMAIN IN
EFFECT FOR ELEVATION ABOVE 3000 FEET TO CAPTURE LOW LEVEL JET.
MORE ADJUSTMENTS LATER THIS MORNING WITH ACTIVE WEATHER...
AS OF 1040 PM EST SATURDAY...
A SLOW MOVING COLD FRONT WILL CONTINUE INCHING EASTWARD THROUGH THE
MID-MISSISSIPPI AND LOWER OHIO RIVER VALLEYS. AHEAD OF THE
FRONT...S-SW LOW LEVEL FLOW WILL INCREASE TO 50 TO 60 KTS AT 850 MB
AND ADVECT PLENTY OF GULF OF MEXICO MOISTURE INTO THE REGION. THIS
MOISTURE WILL BE REALIZED IN ABUNDANT CLOUD COVER...VERY HIGH
SURFACE DEW POINTS FOR LATE DECEMBER. HAVE RAISED PROBABILITY OF
PRECIPITATION ALONG THE CREST OF THE BLUE RIDGE FROM NEAR FLOYD
SOUTHWEST INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA.
ANOTHER REGION TO WATCH FOR PRECIPITATION IS SOUTHEAST WEST
VIRGINIA. THIS AREA WILL BE CLOSEST TO THE ACTUALLY FRONT...AND
WEAK DISTURBANCES ALONG THE FRONT WILL HELP TO BRING PERIODIC
WIDELY SCATTERED COVERAGE TO THIS PART OF THE FORECAST AREA
OVERNIGHT. MAIN AREA OF PRECIPITATION CLOSER TO THE FRONT IS NOT
EXPECTED TO ARRIVE IN THE WESTERN COUNTY WARNING AREA UNTIL AFTER
12Z/7AM. THIS TIMING IS SUPPORT BY THE LATEST HRRR AND RAP MODELS
AS WELL AS THE 18Z LOCAL WRF.
THE HIGH DEW POINTS WILL ALLOW FOR EQUALLY MILD OVERNIGHT LOW
TEMPERATURES. WE ARE EXPECTING NEW RECORD HIGH MINIMUM TEMPERATURES
EVERYWHERE TONIGHT. LOWS WILL RANGE FROM THE UPPER 50S TO NEAR 60
IN THE MOUNTAINS WITH LOWER 60S ACROSS THE PIEDMONT.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
AS OF 350 PM EST SATURDAY...
SUNDAY BEGINS WITH MILD TEMPS AND HEALTHY SOUTH TO SOUTHWEST FLOW
UP ALONG BLUE RIDGE WITH VISIBILITIES SOCKED IN ALONG BLUE
RIDGE...LIGHT SHOWERS...AND WITH HEAVIER BAND OF RAIN SHOWERS JUST
ENTERING FAR SOUTHWEST VA AND NW NC AROUND DAYBREAK MODELS HAVE
DEFINITELY SLOWED THIS DOWN. SEEING EXTREMELY LIMITED INSTABILITY
FOR THUNDER...BUT WENT AHEAD ADDED SLIGHT CHC OF THUNDER BY NOON
FOR MUCH OF SW VA AND NW NC. SHALLOW LINE OF CONVECTION MAY HAVE
VERY GUSTY WINDS WITH IT AS IT ENTERS FAR WESTERN PORTION OF FCST
AREA...BUT MOST MODELS HAVE THIS WEAKENING QUICKLY AS IT ENTERS
DURING THE MID MORNING HOURS. CANT RULE OUT SOME DAMAGING WINDS
WEST OF I-81 AND SOUTH OF 460...MAYBE INTO NW NC. GENERALLY SW
WINDS WILL BE GUSTY AHEAD OF THIS...AND MAY REACH ADVISORY
CRITERIA AT VERY HIGHEST RIDGES...BUT SHOULD BE ISOLATED
ENOUGH...AND NOT HIGH ENOUGH POTENTIAL WITH CONVECTIVE LINE OF
SHOWERS...TO ISSUE A WIND ADVISORY AT THIS TIME.
BY AFTERNOON...PARTS OF THIS LINE OF SHALLOW CONVECTION SHOULD
SNEAK INTO PIEDMONT...BUT THIS MAY NOT OCCUR UNTIL VERY LATE IN
AFTERNOON ACCORDING TO LATEST TRENDS. STILL UPSLOPE FLOW FROM
SOUTH ALONG BLUE RIDGE SHOULD BE ENHANCING PRECIP AMOUNTS THERE
REGARDLESS OF TIMING OF THIS HEAVIER BAND OF SHOWERS...POSSIBLE
ISOLATED THUNDER. NAM STILL IS SLOWEST AND LARGELY DUE TO STRONGLY
INFLUENCE OF THIS WAVE RIDING UP FROM THE SOUTHWEST...AND SPREADS
MORE PRECIP BACK TOWARD THE WEST AGAIN SUNDAY NIGHT AND MONDAY.
SOME HINTS OF THIS IN GFS BUT IT STILL REMAINS MOST PROGRESSIVE.
HEAVIEST RAINFALL FROM NAM AND SOME HIGH RES MODELS SUGGESTED
ALONG BLUE RIDGE...WHILE GFS AND ECMWF MORE OUT INTO PIEDMONT
THROUGH SUNDAY NIGHT AND MONDAY. GENERALLY GOING CLOSER TO
GFS/ECMWF IDEA...AND NOT QUITE AS WET AS GFS...BUT DID ENHANCE THE
RAINFALL ALONG BLUE RIDGE MORE SO THAN WHAT THESE MODELS HAVE.
THUS HAVE INCREASED OVERALL STORM QPF SIGNIFICANTLY...WITH 2.5 TO
3 INCHES FROM BLUE RIDGE EAST. PLEASE READ THE HYDROLOGY SECTION
BELOW FOR MORE DISCUSSION ON THE RAINFALL AND FLOODING
POTENTIAL...BUT FOR NOW HAVE NOT GONE WITH ANY FLOOD
HEADLINES...BUT WILL HIGHLIGHT IN THE HWO.
AS FAR AS TEMPERATURES...STILL LOOKING AT A RECORD BREAKING MILD
AFTERNOON, DESPITE EXTENSIVE CLOUD COVER AND RAIN ACROSS THE
WEST...BUT WITH THE PIEDMONT HOLDING OFF ON RAIN UNTIL
LATE...LIKELY TO SEE MID 70S. JUST ABOUT ALL LOCATIONS SHOULD
TIE OR BREAK A RECORD MAX TEMP FOR THE DATE. SEE CLIMATE SECTION
BELOW FOR RECORDS.
ON MONDAY THE COLDER AIR BEHIND THE FRONT BEGINS TO FILTER
IN...BUT NOT AS FAST AS PREVIOUSLY THOUGHT...AS EVEN THE MORE
PROGRESSIVE GFS HAS SLOWED THINGS DOWN WITH THIS WAVE. COLD AIR
MAY BEGIN TO RUSH IN LATE IN THE DAY IN THE WEST...BUT WILL
PROBABLY NOT ARRIVE IN THE EAST UNTIL MONDAY EVENING. AGAIN...SOME
MODEL DIFFERENCES STILL IN TERMS OF HOW FAR WEST THIS WAVE WILL
SPREAD OR DEVELOP MORE PRECIP...AND HAVE NOT DROPPED POPS TOO LOW
ACROSS THE FAR WEST FOR THIS REASON...BUT THERE COULD BE A BREAK
MOST OF MONDAY FOR MUCH OF THE WEST WHILE SHOWERS STILL PLAGUE THE
BLUE RIDGE AND THE PIEDMONT MOST OF THE DAY BEFORE FINALLY
PUSHING EAST AFTER THE WAVE GOES BY LATE IN THE DAY.
WITH WESTERLY FLOW...SOME UPSLOPE SHOWERS COULD LINGER IN TYPICAL
UPSLOPE FAVORED AREAS OF THE WEST...BUT CHANCES INCREASE FOR
MEASURABLE PRECIP BY LATE MONDAY NIGHT OR EARLY TUES MORNING WITH
STRONG UPPER TROUGH AND SHORT WAVE DIGGING QUICKLY ACROSS THE
AREA. STRONG COLD ADVECTION BY THIS TIME...AND WHILE LOW LEVEL
WINDS MORE WESTERLY...NOT IDEAL FOR BEST UPSLOPE SNOWS...THE
ADVECTION OVER VERY MOIST GROUND JUST UPSTREAM IS STILL A CONCERN.
STILL LEANING MORE TOWARD THE MODELS THAT PRODUCE SOME LIGHT
UPSLOPE ACCUMULATIONS MONDAY NIGHT INTO EARLY TUES MORNING. RIGHT
NOW THINKING A VERY LIGHT ACCUM IN NW NC MTNS...WITH AN INCH OR
TWO IN WESTERN GREENBRIER WV. NAM STILL STINGY ON THIS...BUT
THINKING GFS HAS BEST HANDLE...AND COULD EVEN BE MORE.
THIS WAVE MOVES QUICKLY THROUGH AND SHOULD DRY OUT QUICKLY DURING
THE DAY TUES..WITH CONTINUED STRONG COLD ADVECTION...DOESN`T LOOK
LIKE WIND ADV CRITERIA WIND SPEEDS AT THE MOMENT...AND MUCH COLDER
TEMPS WITH MANY AREAS OF THE WEST REMAINING BELOW FREEZING FOR THE
DAY. WENT WITH COLDER ECMWF MOS-BASED GUIDANCE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 320 PM EST SATURDAY...
STRONG DRY ARCTIC HIGH PRESSURE WILL LEAD TO SOME VERY COLD MORNINGS
NEXT WEEK...POSSIBLY SINGLE DIGITS IN THE DEEPEST COLDEST VALLEYS
WEDNESDAY MORNING. OTHERWISE A RATHER BENIGN PATTERN WITH A DRY COLD
FRONT CROSSING THURSDAY NIGHT. ANOTHER BOUNDARY DROPPING THROUGH THE
UPPER MIDWEST LATE NEXT WEEKEND WILL MEAN SW SURFACE
FLOW...POTENTIALLY PUSHING H85 TEMPS TO NEAR +5C. A COLDER PATTERN
COULD ARRIVE PAST NEXT WEEKEND AS THE POLAR VORTEX DIVES SOUTH
THANKS TO AN UPPER RIDGE POTENTIALLY LINKING FROM GREENLAND TO
ALASKA.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
AS OF 1155 PM EST SATURDAY...
IFR STRATUS COVERED MUCH OF THE SOUTHERN BLUE RIDGE THIS EVENING.
MODERATE CONFIDENCE THAT CEILINGS WILL REMAIN ABOVE IFR AT
KLYH/KDAN/KROA/KBCB THROUGH MIDNIGHT.
OVERNIGHT...MOISTURE TRANSPORT INCREASES ACROSS THE AREA ON
50 TO 60 KT 850 MB WINDS. ANTICIPATE A TREND TOWARD MORE MVFR CIGS
ACROSS THE REGION WITH LOCALIZED IFR CIGS AND MVFR VSBYS. LIGHT
RAIN SHOWERS WILL BECOME MORE NUMEROUS...ESPECIALLY ALONG THE
CREST OF THE BLUE RIDGE AND ALSO NEAR A KLWB-KBLF LINE. WIND GUSTS
UP TO 30 KNOTS ARE POSSIBLE...ESPECIALLY FROM 1AM THROUGH 8AM.
ON SUNDAY MORNING THE SURFACE COLD FRONT MOVES INTO THE
MOUNTAINS...AND MOISTURE WILL CONTINUE TO STREAM ACROSS THE
REGION. LOW CONFIDENCE CONCERNING HOW LOW CEILINGS WILL GET IN THE
AFTERNOON AND EVENING AFTER THE FIRST STRONG BAND OF SHOWERS AND
ISOLATED THUNDERSTORMS GOES THROUGH BUT BEFORE THE FRONT ARRIVES.
FOR NOW HAVE LOWERED INTO THE MVFR TO IFR RANGE.
A REINFORCING WAVE WILL MOVE NORTH ALONG THE FRONT AND
DELAY THE FRONTAL PASSAGE EAST OF THE BLUE RIDGE UNTIL MONDAY.
EXPECT A SHARP WIND SHIFT AS A COLD FRONT COMES THROUGH...THEN
GUSTY NORTHWEST WINDS ON MONDAY. UPSLOPE SNOW SHOWERS ARE EXPECTED
ACROSS SE WV MONDAY NIGHT THROUGH TUESDAY. LOCALIZED MVFR
CONDITIONS ARE EXPECTED.
VFR CEILINGS AND VISIBILITIES RETURN ON WEDNESDAY AND THURSDAY AS HIGH
PRESSURE AND DRIER AIR COME INTO THE REGION.
&&
.HYDROLOGY...
AS OF 335 PM EST SATURDAY...
MODEL TRENDS TOWARD HIGHER PRECIP AMOUNTS SUNDAY NIGHT AND MONDAY...AND
THIS NOT SURPRISING GIVEN SECOND WAVE RIDING UP ALONG FRONT
SLOWING IT DOWN..WITH STRONG FETCH OF MOISTURE ADVECTION FROM
GULF. FORECAST PRECIPITABLE WATER VALUES OF 1.5 TO 1.7 INCHES
WOULD BE RECORD OR NEAR RECORD VALUES FOR DECEMBER. WHILE SOME
HIGH RESOLUTION MODELS ARE LIKELY OVERDOING THE MAXIMUM PRECIP
OUTPUT...SOME SIGNS THAT TWO AREAS OF CONCERN ARE ALONG THE BLUE
RIDGE SUNDAY THROUGH EARLY MONDAY...AND ALSO OUT IN THE PIEDMONT
MAINLY SUNDAY NIGHT AND MONDAY. CURRENT FORECAST AMOUNTS ARE
BETWEEN 2 AND JUST OVER 3 INCHES...AND THIS MAY BE ENOUGH TO CAUSE
NOT ONLY LOCALIZED FLOODING OF SMALL STREAMS AND CREEKS...BUT
COULD BRING THE DAN RIVER UP TO ACTION OR MINOR FLOOD STAGE BY
TUESDAY FROM UPSTREAM AND LOCAL RUNOFF. MAY ALSO HAVE TO WATCH THE
HEADWATERS OF THE NEW RIVER IN NW NC FOR SUNDAY NIGHT...AS WELL
AS ROANOKE RIVER FOR MON/TUES TIME FRAME. IF HIGHER RESOLUTION
MODELS ARE CORRECT...THERE COULD BE MUCH MORE SIGNIFICANT FLOODING
PROBLEMS...BOTH FLASH FLOOD AND RIVER FLOOD. NOT CONFIDENT ENOUGH
YET TO GO WITH A WATCH OF ANY KIND YET.
&&
.CLIMATE...
RECORDS FOR THE WARMEST LOW TEMPERATURE AT EACH CLIMATE SITE FOR
THE MONTH OF DECEMBER ARE AT RISK OF BEING TIED OR BROKEN...ESPECIALLY
ACROSS THE PIEDMONT.
HIGHEST LOW TEMPERATURES FOR THE MONTH OF DECEMBER...
BLACKSBURG 55/DEC 23 1990
ROANOKE 60/DEC 14 1927
LYNCHBURG 62/DEC 16 1971
DANVILLE 60/DEC 6 2011
BLUEFIELD 58/DEC 22 1990
LEWISBURG 58/DEC 28 1982
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY UNTIL NOON EST TODAY FOR VAZ007-009>011-015-
018>020-022>024-034-035.
NC...WIND ADVISORY UNTIL NOON EST TODAY FOR NCZ001-018.
WV...WIND ADVISORY UNTIL NOON EST TODAY FOR WVZ042>045.
&&
$$
SYNOPSIS...KK/SK
NEAR TERM...AMS/DS/KK
SHORT TERM...SK
LONG TERM...KM
AVIATION...AMS/DS
HYDROLOGY...SK
CLIMATE...CF/DS/SK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
112 AM EST SUN DEC 22 2013
.SYNOPSIS...
A VERY MILD AND MOIST AIRMASS WILL REMAIN IN PLACE THROUGH THE
WEEKEND AHEAD OF AN APPROACHING COLD FRONT. SIGNIFICANT RAINFALL
IS POSSIBLE IN MANY LOCATIONS AHEAD OF THE FRONT SUNDAY INTO PARTS
OF MONDAY. THE FRONT WILL MOVE THROUGH THE AREA ON MONDAY...AND
WITH IT WILL COME AN ABRUPT END TO OUR VERY MILD WEATHER. COLDER
HIGH PRESSURE BUILDS OVER THE REGION BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
AS OF 101 AM EST SUNDAY...
ADJUSTED POPS FOR LATEST RADAR TRENDS WITH SCATTERED STORMS
FORMING AHEAD OF THE MAIN BAND OF CONVECTION TO OUR WEST IN THE
OHIO VALLEY. LOW PRESSURE WAS LOCATED IN INDIANA THIS MORNING
WITH COLD FRONT EXTENDING SOUTHWARD ACROSS WESTERN KENTUCKY AND
WESTERN TENNESSEE. COLD FRONT AND ASSOCIATED CONVECTION WILL
CONTINUE TO MOVE EAST TODAY. STRONG SOUTHERN WINDS ADVECTING
PLENTY OF MOISTURE INTO OUR REGION. WIND ADVISORIES REMAIN IN
EFFECT FOR ELEVATION ABOVE 3000 FEET TO CAPTURE LOW LEVEL JET.
MORE ADJUSTMENTS LATER THIS MORNING WITH ACTIVE WEATHER...
AS OF 1040 PM EST SATURDAY...
A SLOW MOVING COLD FRONT WILL CONTINUE INCHING EASTWARD THROUGH THE
MID-MISSISSIPPI AND LOWER OHIO RIVER VALLEYS. AHEAD OF THE
FRONT...S-SW LOW LEVEL FLOW WILL INCREASE TO 50 TO 60 KTS AT 850 MB
AND ADVECT PLENTY OF GULF OF MEXICO MOISTURE INTO THE REGION. THIS
MOISTURE WILL BE REALIZED IN ABUNDANT CLOUD COVER...VERY HIGH
SURFACE DEW POINTS FOR LATE DECEMBER. HAVE RAISED PROBABILITY OF
PRECIPITATION ALONG THE CREST OF THE BLUE RIDGE FROM NEAR FLOYD
SOUTHWEST INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA.
ANOTHER REGION TO WATCH FOR PRECIPITATION IS SOUTHEAST WEST
VIRGINIA. THIS AREA WILL BE CLOSEST TO THE ACTUALLY FRONT...AND
WEAK DISTURBANCES ALONG THE FRONT WILL HELP TO BRING PERIODIC
WIDELY SCATTERED COVERAGE TO THIS PART OF THE FORECAST AREA
OVERNIGHT. MAIN AREA OF PRECIPITATION CLOSER TO THE FRONT IS NOT
EXPECTED TO ARRIVE IN THE WESTERN COUNTY WARNING AREA UNTIL AFTER
12Z/7AM. THIS TIMING IS SUPPORT BY THE LATEST HRRR AND RAP MODELS
AS WELL AS THE 18Z LOCAL WRF.
THE HIGH DEW POINTS WILL ALLOW FOR EQUALLY MILD OVERNIGHT LOW
TEMPERATURES. WE ARE EXPECTING NEW RECORD HIGH MINIMUM TEMPERATURES
EVERYWHERE TONIGHT. LOWS WILL RANGE FROM THE UPPER 50S TO NEAR 60
IN THE MOUNTAINS WITH LOWER 60S ACROSS THE PIEDMONT.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/...
AS OF 350 PM EST SATURDAY...
SUNDAY BEGINS WITH MILD TEMPS AND HEALTHY SOUTH TO SOUTHWEST FLOW
UP ALONG BLUE RIDGE WITH VISIBILITIES SOCKED IN ALONG BLUE
RIDGE...LIGHT SHOWERS...AND WITH HEAVIER BAND OF RAIN SHOWERS JUST
ENTERING FAR SOUTHWEST VA AND NW NC AROUND DAYBREAK MODELS HAVE
DEFINITELY SLOWED THIS DOWN. SEEING EXTREMELY LIMITED INSTABILITY
FOR THUNDER...BUT WENT AHEAD ADDED SLIGHT CHC OF THUNDER BY NOON
FOR MUCH OF SW VA AND NW NC. SHALLOW LINE OF CONVECTION MAY HAVE
VERY GUSTY WINDS WITH IT AS IT ENTERS FAR WESTERN PORTION OF FCST
AREA...BUT MOST MODELS HAVE THIS WEAKENING QUICKLY AS IT ENTERS
DURING THE MID MORNING HOURS. CANT RULE OUT SOME DAMAGING WINDS
WEST OF I-81 AND SOUTH OF 460...MAYBE INTO NW NC. GENERALLY SW
WINDS WILL BE GUSTY AHEAD OF THIS...AND MAY REACH ADVISORY
CRITERIA AT VERY HIGHEST RIDGES...BUT SHOULD BE ISOLATED
ENOUGH...AND NOT HIGH ENOUGH POTENTIAL WITH CONVECTIVE LINE OF
SHOWERS...TO ISSUE A WIND ADVISORY AT THIS TIME.
BY AFTERNOON...PARTS OF THIS LINE OF SHALLOW CONVECTION SHOULD
SNEAK INTO PIEDMONT...BUT THIS MAY NOT OCCUR UNTIL VERY LATE IN
AFTERNOON ACCORDING TO LATEST TRENDS. STILL UPSLOPE FLOW FROM
SOUTH ALONG BLUE RIDGE SHOULD BE ENHANCING PRECIP AMOUNTS THERE
REGARDLESS OF TIMING OF THIS HEAVIER BAND OF SHOWERS...POSSIBLE
ISOLATED THUNDER. NAM STILL IS SLOWEST AND LARGELY DUE TO STRONGLY
INFLUENCE OF THIS WAVE RIDING UP FROM THE SOUTHWEST...AND SPREADS
MORE PRECIP BACK TOWARD THE WEST AGAIN SUNDAY NIGHT AND MONDAY.
SOME HINTS OF THIS IN GFS BUT IT STILL REMAINS MOST PROGRESSIVE.
HEAVIEST RAINFALL FROM NAM AND SOME HIGH RES MODELS SUGGESTED
ALONG BLUE RIDGE...WHILE GFS AND ECMWF MORE OUT INTO PIEDMONT
THROUGH SUNDAY NIGHT AND MONDAY. GENERALLY GOING CLOSER TO
GFS/ECMWF IDEA...AND NOT QUITE AS WET AS GFS...BUT DID ENHANCE THE
RAINFALL ALONG BLUE RIDGE MORE SO THAN WHAT THESE MODELS HAVE.
THUS HAVE INCREASED OVERALL STORM QPF SIGNIFICANTLY...WITH 2.5 TO
3 INCHES FROM BLUE RIDGE EAST. PLEASE READ THE HYDROLOGY SECTION
BELOW FOR MORE DISCUSSION ON THE RAINFALL AND FLOODING
POTENTIAL...BUT FOR NOW HAVE NOT GONE WITH ANY FLOOD
HEADLINES...BUT WILL HIGHLIGHT IN THE HWO.
AS FAR AS TEMPERATURES...STILL LOOKING AT A RECORD BREAKING MILD
AFTERNOON, DESPITE EXTENSIVE CLOUD COVER AND RAIN ACROSS THE
WEST...BUT WITH THE PIEDMONT HOLDING OFF ON RAIN UNTIL
LATE...LIKELY TO SEE MID 70S. JUST ABOUT ALL LOCATIONS SHOULD
TIE OR BREAK A RECORD MAX TEMP FOR THE DATE. SEE CLIMATE SECTION
BELOW FOR RECORDS.
ON MONDAY THE COLDER AIR BEHIND THE FRONT BEGINS TO FILTER
IN...BUT NOT AS FAST AS PREVIOUSLY THOUGHT...AS EVEN THE MORE
PROGRESSIVE GFS HAS SLOWED THINGS DOWN WITH THIS WAVE. COLD AIR
MAY BEGIN TO RUSH IN LATE IN THE DAY IN THE WEST...BUT WILL
PROBABLY NOT ARRIVE IN THE EAST UNTIL MONDAY EVENING. AGAIN...SOME
MODEL DIFFERENCES STILL IN TERMS OF HOW FAR WEST THIS WAVE WILL
SPREAD OR DEVELOP MORE PRECIP...AND HAVE NOT DROPPED POPS TOO LOW
ACROSS THE FAR WEST FOR THIS REASON...BUT THERE COULD BE A BREAK
MOST OF MONDAY FOR MUCH OF THE WEST WHILE SHOWERS STILL PLAGUE THE
BLUE RIDGE AND THE PIEDMONT MOST OF THE DAY BEFORE FINALLY
PUSHING EAST AFTER THE WAVE GOES BY LATE IN THE DAY.
WITH WESTERLY FLOW...SOME UPSLOPE SHOWERS COULD LINGER IN TYPICAL
UPSLOPE FAVORED AREAS OF THE WEST...BUT CHANCES INCREASE FOR
MEASURABLE PRECIP BY LATE MONDAY NIGHT OR EARLY TUES MORNING WITH
STRONG UPPER TROUGH AND SHORT WAVE DIGGING QUICKLY ACROSS THE
AREA. STRONG COLD ADVECTION BY THIS TIME...AND WHILE LOW LEVEL
WINDS MORE WESTERLY...NOT IDEAL FOR BEST UPSLOPE SNOWS...THE
ADVECTION OVER VERY MOIST GROUND JUST UPSTREAM IS STILL A CONCERN.
STILL LEANING MORE TOWARD THE MODELS THAT PRODUCE SOME LIGHT
UPSLOPE ACCUMULATIONS MONDAY NIGHT INTO EARLY TUES MORNING. RIGHT
NOW THINKING A VERY LIGHT ACCUM IN NW NC MTNS...WITH AN INCH OR
TWO IN WESTERN GREENBRIER WV. NAM STILL STINGY ON THIS...BUT
THINKING GFS HAS BEST HANDLE...AND COULD EVEN BE MORE.
THIS WAVE MOVES QUICKLY THROUGH AND SHOULD DRY OUT QUICKLY DURING
THE DAY TUES..WITH CONTINUED STRONG COLD ADVECTION...DOESN`T LOOK
LIKE WIND ADV CRITERIA WIND SPEEDS AT THE MOMENT...AND MUCH COLDER
TEMPS WITH MANY AREAS OF THE WEST REMAINING BELOW FREEZING FOR THE
DAY. WENT WITH COLDER ECMWF MOS-BASED GUIDANCE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 320 PM EST SATURDAY...
STRONG DRY ARCTIC HIGH PRESSURE WILL LEAD TO SOME VERY COLD MORNINGS
NEXT WEEK...POSSIBLY SINGLE DIGITS IN THE DEEPEST COLDEST VALLEYS
WEDNESDAY MORNING. OTHERWISE A RATHER BENIGN PATTERN WITH A DRY COLD
FRONT CROSSING THURSDAY NIGHT. ANOTHER BOUNDARY DROPPING THROUGH THE
UPPER MIDWEST LATE NEXT WEEKEND WILL MEAN SW SURFACE
FLOW...POTENTIALLY PUSHING H85 TEMPS TO NEAR +5C. A COLDER PATTERN
COULD ARRIVE PAST NEXT WEEKEND AS THE POLAR VORTEX DIVES SOUTH
THANKS TO AN UPPER RIDGE POTENTIALLY LINKING FROM GREENLAND TO
ALASKA.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 1155 PM EST SATURDAY...
IFR STRATUS COVERED MUCH OF THE SOUTHERN BLUE RIDGE THIS EVENING.
MODERATE CONFIDENCE THAT CEILINGS WILL REMAIN ABOVE IFR AT
KLYH/KDAN/KROA/KBCB THROUGH MIDNIGHT.
OVERNIGHT...MOISTURE TRANSPORT INCREASES ACROSS THE AREA ON
50 TO 60 KT 850 MB WINDS. ANTICIPATE A TREND TOWARD MORE MVFR CIGS
ACROSS THE REGION WITH LOCALIZED IFR CIGS AND MVFR VSBYS. LIGHT
RAIN SHOWERS WILL BECOME MORE NUMEROUS...ESPECIALLY ALONG THE
CREST OF THE BLUE RIDGE AND ALSO NEAR A KLWB-KBLF LINE. WIND GUSTS
UP TO 30 KNOTS ARE POSSIBLE...ESPECIALLY FROM 1AM THROUGH 8AM.
ON SUNDAY MORNING THE SURFACE COLD FRONT MOVES INTO THE
MOUNTAINS...AND MOISTURE WILL CONTINUE TO STREAM ACROSS THE
REGION. LOW CONFIDENCE CONCERNING HOW LOW CEILINGS WILL GET IN THE
AFTERNOON AND EVENING AFTER THE FIRST STRONG BAND OF SHOWERS AND
ISOLATED THUNDERSTORMS GOES THROUGH BUT BEFORE THE FRONT ARRIVES.
FOR NOW HAVE LOWERED INTO THE MVFR TO IFR RANGE.
A REINFORCING WAVE WILL MOVE NORTH ALONG THE FRONT AND
DELAY THE FRONTAL PASSAGE EAST OF THE BLUE RIDGE UNTIL MONDAY.
EXPECT A SHARP WIND SHIFT AS A COLD FRONT COMES THROUGH...THEN
GUSTY NORTHWEST WINDS ON MONDAY. UPSLOPE SNOW SHOWERS ARE EXPECTED
ACROSS SE WV MONDAY NIGHT THROUGH TUESDAY. LOCALIZED MVFR
CONDITIONS ARE EXPECTED.
VFR CEILINGS AND VISIBILITIES RETURN ON WEDNESDAY AND THURSDAY AS HIGH
PRESSURE AND DRIER AIR COME INTO THE REGION.
&&
.HYDROLOGY...
AS OF 335 PM EST SATURDAY...
MODEL TRENDS TOWARD HIGHER PRECIP AMOUNTS SUNDAY NIGHT AND MONDAY...AND
THIS NOT SURPRISING GIVEN SECOND WAVE RIDING UP ALONG FRONT
SLOWING IT DOWN..WITH STRONG FETCH OF MOISTURE ADVECTION FROM
GULF. FORECAST PRECIPITABLE WATER VALUES OF 1.5 TO 1.7 INCHES
WOULD BE RECORD OR NEAR RECORD VALUES FOR DECEMBER. WHILE SOME
HIGH RESOLUTION MODELS ARE LIKELY OVERDOING THE MAXIMUM PRECIP
OUTPUT...SOME SIGNS THAT TWO AREAS OF CONCERN ARE ALONG THE BLUE
RIDGE SUNDAY THROUGH EARLY MONDAY...AND ALSO OUT IN THE PIEDMONT
MAINLY SUNDAY NIGHT AND MONDAY. CURRENT FORECAST AMOUNTS ARE
BETWEEN 2 AND JUST OVER 3 INCHES...AND THIS MAY BE ENOUGH TO CAUSE
NOT ONLY LOCALIZED FLOODING OF SMALL STREAMS AND CREEKS...BUT
COULD BRING THE DAN RIVER UP TO ACTION OR MINOR FLOOD STAGE BY
TUESDAY FROM UPSTREAM AND LOCAL RUNOFF. MAY ALSO HAVE TO WATCH THE
HEADWATERS OF THE NEW RIVER IN NW NC FOR SUNDAY NIGHT...AS WELL
AS ROANOKE RIVER FOR MON/TUES TIME FRAME. IF HIGHER RESOLUTION
MODELS ARE CORRECT...THERE COULD BE MUCH MORE SIGNIFICANT FLOODING
PROBLEMS...BOTH FLASH FLOOD AND RIVER FLOOD. NOT CONFIDENT ENOUGH
YET TO GO WITH A WATCH OF ANY KIND YET.
&&
.CLIMATE...
RECORDS FOR THE WARMEST LOW TEMPERATURE AT EACH CLIMATE SITE FOR
THE MONTH OF DECEMBER ARE AT RISK OF BEING TIED OR BROKEN...ESPECIALLY
ACROSS THE PIEDMONT.
HIGHEST LOW TEMPERATURES FOR THE MONTH OF DECEMBER...
BLACKSBURG 55/DEC 23 1990
ROANOKE 60/DEC 14 1927
LYNCHBURG 62/DEC 16 1971
DANVILLE 60/DEC 6 2011
BLUEFIELD 58/DEC 22 1990
LEWISBURG 58/DEC 28 1982
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY UNTIL NOON EST TODAY FOR VAZ007-009-015-018>020-
022>024-034-035.
NC...WIND ADVISORY UNTIL NOON EST TODAY FOR NCZ001-018.
WV...WIND ADVISORY UNTIL NOON EST TODAY FOR WVZ043>045.
&&
$$
SYNOPSIS...KK/SK
NEAR TERM...AMS/DS/KK
SHORT TERM...SK
LONG TERM...KM
AVIATION...AMS/DS
HYDROLOGY...SK
CLIMATE...CF/DS/SK
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1158 PM EST SAT DEC 21 2013
.SYNOPSIS...
A VERY MILD AND MOIST AIRMASS WILL REMAIN IN PLACE THROUGH THE
WEEKEND AHEAD OF AN APPROACHING COLD FRONT. SIGNIFICANT RAINFALL
IS POSSIBLE IN MANY LOCATIONS AHEAD OF THE FRONT SUNDAY INTO PARTS
OF MONDAY. THE FRONT WILL MOVE THROUGH THE AREA ON MONDAY...AND
WITH IT WILL COME AN ABRUPT END TO OUR VERY MILD WEATHER. COLDER
HIGH PRESSURE BUILDS OVER THE REGION BY THE MIDDLE OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 1040 PM EST SATURDAY...
A SLOW MOVING COLD FRONT WILL CONTINUE INCHING EASTWARD THROUGH THE
MID-MISSISSIPPI AND LOWER OHIO RIVER VALLEYS. AHEAD OF THE
FRONT...S-SW LOW LEVEL FLOW WILL INCREASE TO 50 TO 60 KTS AT 850 MB
AND ADVECT PLENTY OF GULF OF MEXICO MOISTURE INTO THE REGION. THIS
MOISTURE WILL BE REALIZED IN ABUNDANT CLOUD COVER...VERY HIGH
SURFACE DEW POINTS FOR LATE DECEMBER. HAVE RAISED PROBABILITY OF
PRECIPITATION ALONG THE CREST OF THE BLUE RIDGE FROM NEAR FLOYD
SOUTHWEST INTO THE NORTHERN MOUNTAINS OF NORTH CAROLINA.
ANOTHER REGION TO WATCH FOR PRECIPITATION IS SOUTHEAST WEST
VIRGINIA. THIS AREA WILL BE CLOSEST TO THE ACTUALLY FRONT...AND
WEAK DISTURBANCES ALONG THE FRONT WILL HELP TO BRING PERIODIC
WIDELY SCATTERED COVERAGE TO THIS PART OF THE FORECAST AREA
OVERNIGHT. MAIN AREA OF PRECIPITATION CLOSER TO THE FRONT IS NOT
EXPECTED TO ARRIVE IN THE WESTERN COUNTY WARNING AREA UNTIL AFTER
12Z/7AM. THIS TIMING IS SUPPORT BY THE LATEST HRRR AND RAP MODELS
AS WELL AS THE 18Z LOCAL WRF.
THE HIGH DEW POINTS WILL ALLOW FOR EQUALLY MILD OVERNIGHT LOW
TEMPERATURES. WE ARE EXPECTING NEW RECORD HIGH MINIMUM TEMPERATURES
EVERYWHERE TONIGHT. LOWS WILL RANGE FROM THE UPPER 50S TO NEAR 60
IN THE MOUNTAINS WITH LOWER 60S ACROSS THE PIEDMONT.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
AS OF 350 PM EST SATURDAY...
SUNDAY BEGINS WITH MILD TEMPS AND HEALTHY SOUTH TO SOUTHWEST FLOW
UP ALONG BLUE RIDGE WITH VISIBILITIES SOCKED IN ALONG BLUE
RIDGE...LIGHT SHOWERS...AND WITH HEAVIER BAND OF RAIN SHOWERS JUST
ENTERING FAR SOUTHWEST VA AND NW NC AROUND DAYBREAK MODELS HAVE
DEFINITELY SLOWED THIS DOWN. SEEING EXTREMELY LIMITED INSTABILITY
FOR THUNDER...BUT WENT AHEAD ADDED SLIGHT CHC OF THUNDER BY NOON
FOR MUCH OF SW VA AND NW NC. SHALLOW LINE OF CONVECTION MAY HAVE
VERY GUSTY WINDS WITH IT AS IT ENTERS FAR WESTERN PORTION OF FCST
AREA...BUT MOST MODELS HAVE THIS WEAKENING QUICKLY AS IT ENTERS
DURING THE MID MORNING HOURS. CANT RULE OUT SOME DAMAGING WINDS
WEST OF I-81 AND SOUTH OF 460...MAYBE INTO NW NC. GENERALLY SW
WINDS WILL BE GUSTY AHEAD OF THIS...AND MAY REACH ADVISORY
CRITERIA AT VERY HIGHEST RIDGES...BUT SHOULD BE ISOLATED
ENOUGH...AND NOT HIGH ENOUGH POTENTIAL WITH CONVECTIVE LINE OF
SHOWERS...TO ISSUE A WIND ADVISORY AT THIS TIME.
BY AFTERNOON...PARTS OF THIS LINE OF SHALLOW CONVECTION SHOULD
SNEAK INTO PIEDMONT...BUT THIS MAY NOT OCCUR UNTIL VERY LATE IN
AFTERNOON ACCORDING TO LATEST TRENDS. STILL UPSLOPE FLOW FROM
SOUTH ALONG BLUE RIDGE SHOULD BE ENHANCING PRECIP AMOUNTS THERE
REGARDLESS OF TIMING OF THIS HEAVIER BAND OF SHOWERS...POSSIBLE
ISOLATED THUNDER. NAM STILL IS SLOWEST AND LARGELY DUE TO STRONGLY
INFLUENCE OF THIS WAVE RIDING UP FROM THE SOUTHWEST...AND SPREADS
MORE PRECIP BACK TOWARD THE WEST AGAIN SUNDAY NIGHT AND MONDAY.
SOME HINTS OF THIS IN GFS BUT IT STILL REMAINS MOST PROGRESSIVE.
HEAVIEST RAINFALL FROM NAM AND SOME HIGH RES MODELS SUGGESTED
ALONG BLUE RIDGE...WHILE GFS AND ECMWF MORE OUT INTO PIEDMONT
THROUGH SUNDAY NIGHT AND MONDAY. GENERALLY GOING CLOSER TO
GFS/ECMWF IDEA...AND NOT QUITE AS WET AS GFS...BUT DID ENHANCE THE
RAINFALL ALONG BLUE RIDGE MORE SO THAN WHAT THESE MODELS HAVE.
THUS HAVE INCREASED OVERALL STORM QPF SIGNIFICANTLY...WITH 2.5 TO
3 INCHES FROM BLUE RIDGE EAST. PLEASE READ THE HYDROLOGY SECTION
BELOW FOR MORE DISCUSSION ON THE RAINFALL AND FLOODING
POTENTIAL...BUT FOR NOW HAVE NOT GONE WITH ANY FLOOD
HEADLINES...BUT WILL HIGHLIGHT IN THE HWO.
AS FAR AS TEMPERATURES...STILL LOOKING AT A RECORD BREAKING MILD
AFTERNOON, DESPITE EXTENSIVE CLOUD COVER AND RAIN ACROSS THE
WEST...BUT WITH THE PIEDMONT HOLDING OFF ON RAIN UNTIL
LATE...LIKELY TO SEE MID 70S. JUST ABOUT ALL LOCATIONS SHOULD
TIE OR BREAK A RECORD MAX TEMP FOR THE DATE. SEE CLIMATE SECTION
BELOW FOR RECORDS.
ON MONDAY THE COLDER AIR BEHIND THE FRONT BEGINS TO FILTER
IN...BUT NOT AS FAST AS PREVIOUSLY THOUGHT...AS EVEN THE MORE
PROGRESSIVE GFS HAS SLOWED THINGS DOWN WITH THIS WAVE. COLD AIR
MAY BEGIN TO RUSH IN LATE IN THE DAY IN THE WEST...BUT WILL
PROBABLY NOT ARRIVE IN THE EAST UNTIL MONDAY EVENING. AGAIN...SOME
MODEL DIFFERENCES STILL IN TERMS OF HOW FAR WEST THIS WAVE WILL
SPREAD OR DEVELOP MORE PRECIP...AND HAVE NOT DROPPED POPS TOO LOW
ACROSS THE FAR WEST FOR THIS REASON...BUT THERE COULD BE A BREAK
MOST OF MONDAY FOR MUCH OF THE WEST WHILE SHOWERS STILL PLAGUE THE
BLUE RIDGE AND THE PIEDMONT MOST OF THE DAY BEFORE FINALLY
PUSHING EAST AFTER THE WAVE GOES BY LATE IN THE DAY.
WITH WESTERLY FLOW...SOME UPSLOPE SHOWERS COULD LINGER IN TYPICAL
UPSLOPE FAVORED AREAS OF THE WEST...BUT CHANCES INCREASE FOR
MEASURABLE PRECIP BY LATE MONDAY NIGHT OR EARLY TUES MORNING WITH
STRONG UPPER TROUGH AND SHORT WAVE DIGGING QUICKLY ACROSS THE
AREA. STRONG COLD ADVECTION BY THIS TIME...AND WHILE LOW LEVEL
WINDS MORE WESTERLY...NOT IDEAL FOR BEST UPSLOPE SNOWS...THE
ADVECTION OVER VERY MOIST GROUND JUST UPSTREAM IS STILL A CONCERN.
STILL LEANING MORE TOWARD THE MODELS THAT PRODUCE SOME LIGHT
UPSLOPE ACCUMULATIONS MONDAY NIGHT INTO EARLY TUES MORNING. RIGHT
NOW THINKING A VERY LIGHT ACCUM IN NW NC MTNS...WITH AN INCH OR
TWO IN WESTERN GREENBRIER WV. NAM STILL STINGY ON THIS...BUT
THINKING GFS HAS BEST HANDLE...AND COULD EVEN BE MORE.
THIS WAVE MOVES QUICKLY THROUGH AND SHOULD DRY OUT QUICKLY DURING
THE DAY TUES..WITH CONTINUED STRONG COLD ADVECTION...DOESN`T LOOK
LIKE WIND ADV CRITERIA WIND SPEEDS AT THE MOMENT...AND MUCH COLDER
TEMPS WITH MANY AREAS OF THE WEST REMAINING BELOW FREEZING FOR THE
DAY. WENT WITH COLDER ECMWF MOS-BASED GUIDANCE.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 320 PM EST SATURDAY...
STRONG DRY ARCTIC HIGH PRESSURE WILL LEAD TO SOME VERY COLD MORNINGS
NEXT WEEK...POSSIBLY SINGLE DIGITS IN THE DEEPEST COLDEST VALLEYS
WEDNESDAY MORNING. OTHERWISE A RATHER BENIGN PATTERN WITH A DRY COLD
FRONT CROSSING THURSDAY NIGHT. ANOTHER BOUNDARY DROPPING THROUGH THE
UPPER MIDWEST LATE NEXT WEEKEND WILL MEAN SW SURFACE
FLOW...POTENTIALLY PUSHING H85 TEMPS TO NEAR +5C. A COLDER PATTERN
COULD ARRIVE PAST NEXT WEEKEND AS THE POLAR VORTEX DIVES SOUTH
THANKS TO AN UPPER RIDGE POTENTIALLY LINKING FROM GREENLAND TO
ALASKA.
&&
.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 1155 PM EST SATURDAY...
IFR STRATUS COVERED MUCH OF THE SOUTHERN BLUE RIDGE THIS EVENING.
MODERATE CONFIDENCE THAT CEILINGS WILL REMAIN ABOVE IFR AT
KLYH/KDAN/KROA/KBCB THROUGH MIDNIGHT.
OVERNIGHT...MOISTURE TRANSPORT INCREASES ACROSS THE AREA ON
50 TO 60 KT 850 MB WINDS. ANTICIPATE A TREND TOWARD MORE MVFR CIGS
ACROSS THE REGION WITH LOCALIZED IFR CIGS AND MVFR VSBYS. LIGHT
RAIN SHOWERS WILL BECOME MORE NUMEROUS...ESPECIALLY ALONG THE
CREST OF THE BLUE RIDGE AND ALSO NEAR A KLWB-KBLF LINE. WIND GUSTS
UP TO 30 KNOTS ARE POSSIBLE...ESPECIALLY FROM 1AM THROUGH 8AM.
ON SUNDAY MORNING THE SURFACE COLD FRONT MOVES INTO THE
MOUNTAINS...AND MOISTURE WILL CONTINUE TO STREAM ACROSS THE
REGION. LOW CONFIDENCE CONCERNING HOW LOW CEILINGS WILL GET IN THE
AFTERNOON AND EVENING AFTER THE FIRST STRONG BAND OF SHOWERS AND
ISOLATED THUNDERSTORMS GOES THROUGH BUT BEFORE THE FRONT ARRIVES.
FOR NOW HAVE LOWERED INTO THE MVFR TO IFR RANGE.
A REINFORCING WAVE WILL MOVE NORTH ALONG THE FRONT AND
DELAY THE FRONTAL PASSAGE EAST OF THE BLUE RIDGE UNTIL MONDAY.
EXPECT A SHARP WIND SHIFT AS A COLD FRONT COMES THROUGH...THEN
GUSTY NORTHWEST WINDS ON MONDAY. UPSLOPE SNOW SHOWERS ARE EXPECTED
ACROSS SE WV MONDAY NIGHT THROUGH TUESDAY. LOCALIZED MVFR
CONDITIONS ARE EXPECTED.
VFR CEILINGS AND VISIBILITIES RETURN ON WEDNESDAY AND THURSDAY AS HIGH
PRESSURE AND DRIER AIR COME INTO THE REGION.
&&
.HYDROLOGY...
AS OF 335 PM EST SATURDAY...
MODEL TRENDS TOWARD HIGHER PRECIP AMOUNTS SUNDAY NIGHT AND MONDAY...AND
THIS NOT SURPRISING GIVEN SECOND WAVE RIDING UP ALONG FRONT
SLOWING IT DOWN..WITH STRONG FETCH OF MOISTURE ADVECTION FROM
GULF. FORECAST PRECIPITABLE WATER VALUES OF 1.5 TO 1.7 INCHES
WOULD BE RECORD OR NEAR RECORD VALUES FOR DECEMBER. WHILE SOME
HIGH RESOLUTION MODELS ARE LIKELY OVERDOING THE MAXIMUM PRECIP
OUTPUT...SOME SIGNS THAT TWO AREAS OF CONCERN ARE ALONG THE BLUE
RIDGE SUNDAY THROUGH EARLY MONDAY...AND ALSO OUT IN THE PIEDMONT
MAINLY SUNDAY NIGHT AND MONDAY. CURRENT FORECAST AMOUNTS ARE
BETWEEN 2 AND JUST OVER 3 INCHES...AND THIS MAY BE ENOUGH TO CAUSE
NOT ONLY LOCALIZED FLOODING OF SMALL STREAMS AND CREEKS...BUT
COULD BRING THE DAN RIVER UP TO ACTION OR MINOR FLOOD STAGE BY
TUESDAY FROM UPSTREAM AND LOCAL RUNOFF. MAY ALSO HAVE TO WATCH THE
HEADWATERS OF THE NEW RIVER IN NW NC FOR SUNDAY NIGHT...AS WELL
AS ROANOKE RIVER FOR MON/TUES TIME FRAME. IF HIGHER RESOLUTION
MODELS ARE CORRECT...THERE COULD BE MUCH MORE SIGNIFICANT FLOODING
PROBLEMS...BOTH FLASH FLOOD AND RIVER FLOOD. NOT CONFIDENT ENOUGH
YET TO GO WITH A WATCH OF ANY KIND YET.
&&
.CLIMATE...
RECORDS FOR THE WARMEST LOW TEMPERATURE AT EACH CLIMATE SITE FOR
THE MONTH OF DECEMBER ARE AT RISK OF BEING TIED OR BROKEN...ESPECIALLY
ACROSS THE PIEDMONT.
HIGHEST LOW TEMPERATURES FOR THE MONTH OF DECEMBER...
BLACKSBURG 55/DEC 23 1990
ROANOKE 60/DEC 14 1927
LYNCHBURG 62/DEC 16 1971
DANVILLE 60/DEC 6 2011
BLUEFIELD 58/DEC 22 1990
LEWISBURG 58/DEC 28 1982
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WIND ADVISORY UNTIL NOON EST SUNDAY FOR VAZ007-009-015-018>020-
022>024-034-035.
NC...WIND ADVISORY UNTIL NOON EST SUNDAY FOR NCZ001-018.
WV...WIND ADVISORY UNTIL NOON EST SUNDAY FOR WVZ043>045.
&&
$$
SYNOPSIS...KK/SK
NEAR TERM...AMS/DS
SHORT TERM...SK
LONG TERM...KM
AVIATION...AMS/DS
HYDROLOGY...SK
CLIMATE...CF/DS/SK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1128 PM CST SAT DEC 21 2013
.UPDATE...
ISSUED AT 900 PM CST SAT DEC 21 2013
THE MAIN FOCUS THIS EVENING HAS BEEN WITH WHETHER OR NOT A TIER
OF COUNTIES NEEDS TO BE ADDED ONTO THE CURRENT ADVISORY/WARNING.
CURRENTLY...SOME VERY LIGHT FREEZING DRIZZLE HAS BEEN FALLING
ACROSS PORTIONS OF THE AREA IN RESPONSE TO SOME WEAK 280-290K
ISENTROPIC LIFT THAT IS OCCURRING AHEAD OF THE MAIN TROUGH. BEFORE
WE SEE ANY SNOW DEVELOP LOCALLY...THE DRY LAYER BETWEEN 800-600MB
WILL HAVE TO SATURATE OUT. THE 22.01 RAP RH FIELDS SHOW SOME
INCREASING RH IN THAT COLUMN COMING IN FROM THE SOUTHEAST AND
SOUTH AROUND AND AFTER 6Z. THIS COINCIDES FAIRLY WELL WITH WHAT
22.00Z HRRR REFLECTIVITY GRAPHICS SHOW WITH THE SNOW MOVING UP
INTO NORTHEAST IOWA AROUND/AFTER 6Z.
BASED ON THE PATH OF THE 500MB VORT MAX THROUGH NORTHERN ILLINOIS
AND THE CURRENT HEAVY SNOW THAT IS FALLING ACROSS PORTIONS OF
KANSAS...CONFIDENCE IS STILL HIGH IN THE HEAVY SNOW THAT IS
FORECAST TO OCCUR OVERNIGHT INTO TOMORROW MORNING ACROSS THE
WINTER STORM WARNING AREA. IT STILL LOOKS LIKE THE 2AM TO 10AM
TIME FRAME IS WHEN THE HEAVIEST SNOW WILL COME THROUGH WITH SOME
1...MAYBE 2...INCH PER HOUR SNOWFALL RATES IN THIS BAND.
FURTHER TO THE NORTHWEST...THE 22.00Z AND PRIOR RUNS HAVE BEEN
HINTING AT A SECONDARY DEFORMATION BAND SETTING UP ALONG THE
ADVISORY COUNTIES AND POSSIBLE JUST TO THE WEST OF IT. THIS LIFT
IS COMING IN THE 500-300MB LEVELS AND IS OVER THE DRY LAYER
BETWEEN 800-600MB...SO THERE IS THE QUESTION OF WHETHER THE DRY
LAYER WILL BE DEEP ENOUGH TO KEEP ANY SNOW/ICE FROM MAKING IT TO
THE GROUND. 22.01Z RAP SOUNDINGS SHOW THIS DRY LAYER WINNING OUT
THROUGH MUCH OF THE OVERNIGHT HOURS BEFORE BRIEFLY SATURATING UP
ENOUGH TO ALLOW FOR SOME SNOW TO FINALLY OCCUR TOWARD DAYBREAK.
DUE TO THE SHORT LENGTH OF WHEN THIS SNOW COULD FALL...HAVE
DECIDED TO NOT MAKE ANY CHANGES TO THE CURRENT ADVISORY...BUT WILL
UP THE TOTALS AN INCH OR TWO FROM CHARLES CITY IOWA NORTH
NORTHEAST TOWARD BLACK RIVER FALLS WISCONSIN FOR WHERE IT LOOKS
LIKE THIS BAND COULD SET UP. WILL CONTINUE TO WATCH DOWNSTREAM
OBS FOR WHETHER ANY FUTURE ADJUSTMENTS NEED TO BE MADE TO THIS
AREA.
&&
.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 300 PM CST SAT DEC 21 2013
MAIN FORECAST CONCERNS THIS PACKAGE...WINTER STORM TO MOVE ACROSS
THE AREA TONIGHT/SUN...LINGERING SNOW CHANCES SUN NIGHT.
DATA ANALYSIS AT 18Z HAD A BROAD AREA OF HIGH PRESSURE OVER CENTRAL
CANADA AND DEEPENING LOW PRESSURE OVER ARKANSAS. PER WV IMAGERY...
SHORTWAVE OF INTEREST FOR TONIGHT/SUNDAY HAS ROUNDED THE BASE OF THE
TROUGH AND COULD BE SEEN LIFTING NORTHEAST ACROSS TX AT MID-DAY.
UPPER MIDWEST UNDER THE INFLUENCE OF THE HIGH TODAY...WITH GENERALLY
QUIET WEATHER BUT MOSTLY CLOUDY TO CLOUDY SKIES WITH ABUNDANT LOW
LEVEL MOISTURE TRAPPED UNDER AN INVERSION NEAR 850MB. MID-DAY TEMPS
ACROSS MUCH OF THE REGION NEAR SEASONAL NORMALS.
21.12Z MODELS LOOK TO HAVE INITIALIZED WITHOUT LARGE ERRORS. MODELS
CONTINUE TO CONVERGE TOWARD A TIGHTER/COMMON CONSENSUS THRU SUN
NIGHT...TOWARD THE EARLIER ECMWF/CAN-GEM RUNS. THIS AS THE AZ/
NORTHERN MEX/WEST TX SHORTWAVE ENERGY LIFTS QUICKLY NORTHEAST
TONIGHT/SUN TO WESTERN QUEBEC BY 00Z MON...AND ENERGY OVER BC/ALB
CARVES OUT A RATHER DEEP TROUGH OVER THE REGION LATER SUN NIGHT.
MODEL DIFFERENCES THAT DO REMAIN IMPACT SNOW AMOUNTS TONIGHT/SUNDAY.
CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED MODELS ALL REASONABLE ON
THE SFC MASS FIELDS ACROSS THE CENTRAL CONUS. PER WV IMAGERY...
MODELS ALL APPEAR GOOD WITH THE SOUTHERN PLAINS SHORTWAVE ENERGY.
BLEND OF THE MODELS LOOKED GOOD WITH THE 12-18Z PRECIP ASSOCIATED
WITH THE MID LEVEL TROUGH AND SFC TROUGH/FRONT FROM THE SOUTHERN
PLAINS LOW THRU OHIO VALLEY. WITH MODELS TRENDING MORE SIMILAR...
TOWARD A TIGHTER COMPROMISE SOLUTION...FAVORED THE MODEL/ENSEMBLE
CONSENSUS. GIVEN THE SNOW AMOUNT DIFFERENCES...AND A SLIGHT TREND
TOWARD DRIER/LESS SNOW...SHORT-TERM FCST CONFIDENCE IS SHY OF GOOD
THIS CYCLE.
IN THE SHORT TERM...MODEL SOUNDINGS SHOWING SATURATION TO ABOUT
800MB AND CLOUD TOP TEMPS IN THE -5C TO -10C RANGE THIS AFTERNOON.
FALLING PRESSURES/DIVERGENCE ALOFT STARTING TO SPREAD ACROSS THE
AREA...PROVIDING A LITTLE LIFT TO THE LOWER LEVELS AND GETTING FEW
REPORTS OF -FZDZ. MODEL SOUNDINGS SHOWING IT TAKES THRU MUCH OF
THE EVENING FOR THE COLUMN TO SATURATE FOR ICE IN THE LOWER CLOUD/
MOISTURE LAYER. AVIATION FORECASTER DID ADD MENTION OF -FZDZ WITH
THE -SN CHANCES TO MUCH OF THE FCST AREA THRU THE EVENING.
VIGOROUS TX SHORTWAVE LIFTS TO NEAR THE IA/MO/IL INTERSECTION BY
12Z SUN...WHILE THE SFC LOW LIFTS TO THE VICINITY OF NORTHWEST OH.
850MB LOW LIFTS ACROSS MO TO NEAR OR EAST OF CHICAGO BY 12Z SUN.
ON THIS TRACK...MUCH OF THE STRONGER/DEEPER LOWER LEVEL THERMO-
DYNAMIC FORCING JUST CLIPS THE SOUTHEAST END OF THE FCST AREA.
BULK OF THE FORCING/LIFT TO PASS ACROSS THE REST OF THE FCST AREA
WILL BE FROM UPPER LEVEL PV ADVECTION/DIVERGENCE/LIFT AHEAD OF THE
VIGOROUS SHORTWAVE AND DIVERGENCE ALOFT BETWEEN AT LEAST SEMI-
COUPLED JET MAXES. PLENTY OF MOIST/UNSTABLE AIR BEING LIFTED NORTH
OF THIS SYSTEM...WITH DYNAMICS/LIFT AHEAD OF THE ADVANCING TROUGH
PRODUCING ABUNDANT CONVECTION/PRECIP NEAR THE SFC TROUGH/FRONT
ACROSS THE MID MS TO OH VALLEYS. THE SLIGHT DROP IN PRECIP
PRODUCTION ACROSS THE AREA TONIGHT/SUN MAY BE TIED TO THIS WALL OF
CONVECTION ROBBING MUCH OF THE INCOMING MOISTURE BEFORE IT WOULD
REACH THE AREA. GFS/ECMWF/NAM NOW BARELY PRODUCE ENOUGH QPF FOR
ADVISORY SNOW AMOUNTS OVER THE SOUTHEAST END OF THE FCST AREA
WHILE CAN-GEM STILL HOLDS ONTO WARNING/ADVISORY AMOUNTS ACROSS THE
SOUTHEAST 1/3 TO HALF OF THE FCST AREA. WITH MUCH OF THE LIFT
ABOVE 850MB AND EVEN 700MB...AND VERTICAL MOTIONS NOT OVERLY
STRONG EXCEPT OVER THE SOUTHEAST END OF THE FCST AREA...HAVING A
HARD TIME SEEING SNOW-WATER RATIOS IN THE 15 TO 20 TO 1 RANGED TO
PRODUCE THE HIGHER SNOWFALL TOTALS. LOWERED SNOW AMOUNTS A
BIT...BUT LEFT THEM IN RANGES TO SUPPORT THE CURRENT ADVISORIES/
WARNINGS...WHICH WILL BE LEFT AS FOR NOW. TIGHTER PRESSURE
GRADIENT AND BRISK NORTHWEST WINDS FOR SOME BLOWING/DRIFTING OF
NEW SNOW WILL ADD THAT TO THE WINTER WEATHER HEADLINES FOR LATER
TONIGHT/MUCH OF SUNDAY.
FORCING/LIFT WITH THIS SHORTWAVE EXITS DURING THE MORNING WITH
ATTENTION QUICKLY TURNING TO THE NORTHERN STREAM SHORTWAVE DROPPING
TOWARD THE AREA. STRONG HGT FALLS TO MOVE ACROSS THE AREA LATER SUN/
SUN NIGHT WITH ANOTHER ROUND OF STRONG PV ADVECTION AND DIVERGENCE/
LIFT ALOFT. MUCH COLDER COLUMN OVER THE AREA BY SUN NIGHT WITH THE
DENDRITIC GROWTH ZONE LOWER...IN THE 850-700MB RANGE. INCREASING
MODEL SIGNAL/CONSENSUS FOR THE FEATURE TO PRODUCE 1 TO PERHAPS 2
INCHES OF SNOW ACROSS THE NORTHEAST 2/3 OF THE FCST AREA SUN
AFTERNOON/NIGHT AND RAISED SNOW CHANCES THESE PERIODS INTO THE 70-80
PERCENT RANGE OVER THAT PORTION OF THE FCST AREA. USED THE MODEL/
ENSEMBLE CONSENSUS FOR LOWS/HIGHS TONIGHT THRU SUN NIGHT...PLENTY OF
CLOUDS THRU SUN NIGHT AND BY LATER TONIGHT STRONGER GRADIENT SFC
WINDS TO KEEP THE BOUNDARY LAYER STIRRED.
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 300 PM CST SAT DEC 21 2013
MAIN FORECAST CONCERNS FOR MONDAY THROUGH TUESDAY NIGHT...SNOW
CHANCES WITH NORTHWEST FLOW SHORTWAVES AND TEMPERATURES THRU THE
PERIOD.
21.12Z MODELS IN IMPROVING AGREEMENT AS THE DEEP MID LEVEL TROUGH
MOVES ACROSS THE REGION MONDAY THEN HGTS RISING QUICKLY WITH ITS
PASSAGE AND SHORTWAVE RIDGING BUILDING IN MON NIGHT. CONSENSUS
REMAINS RATHER TIGHT AS THE SHORTWAVE RIDGE QUICKLY PASSES TUE...
THEN THE NEXT STRONG NORTHWEST FLOW TROUGH DROPS INTO THE REGION AND
SENDS MID LEVEL HGTS CRASHING AGAIN. TREND THRU THE PERIOD FAVORS
STRONGER/SLOWER OF THE EARLIER RUNS. FCST CONFIDENCE IN THE MON THRU
TUE NIGHT PERIOD IS AVERAGE TO GOOD THIS CYCLE.
PLENTY OF SFC-600MB MOISTURE...A COLD COLUMN...DEEP/TIGHT CYCLONIC
CONVERGENCE AND A SFC TROUGH COMBINE TO CONTINUE WRINGING OUT SOME
LIGHT SNOW ACROSS MUCH OF THE FCST AREA ON MON...RAISED -SN CHANCE
TO THE 50-70 PERCENT RANGE OVER THE EAST HALF OF THE FCST AREA...
MAINLY DURING THE MORNING AHEAD OF THE MID LEVEL TROUGH AXIS. -SN
CHANCES WANE MON AFTERNOON WITH PASSAGE OF THE 700-500MB TROUGH
AXIS. RATHER SHARP SFC-700MB RIDGE AXIS AND SUBSIDENCE WITHIN IT
BUILDING EAST LATE MON/MON NIGHT SHOULD HELP CLEAR OUT THE CLOUDS
BUT WITH THE SLOWING TREND AMONG THE MODELS...THIS MAY NOT OCCUR
UNTIL LATE MON NIGHT OVER THE EAST END OF THE FCST AREA. MORE CLOUDS
FOR MORE OF THE NIGHT MON NIGHT TO HAVE AN IMPACT ON LOW TEMPS.
WARMER MODEL CONSENSUS LOWS MON ESPECIALLY OVER THE EAST HALF OF THE
FCST AREA LOOK GOOD. ANY SHOT AT CLEAR SKIES/SOME SUNSHINE APPEAR
SHORT LIVED AS SFC-700MB RIDGE AXIS PASSES QUICKLY WITH INCREASING
LOWER LEVEL WARM ADVECTION AND DEEPER MOISTURE AHEAD OF THE NEXT
TROUGH SPREADING RAPIDLY ACROSS THE REGION ON TUE. GIVEN THE DEPTH/
STRENGTH OF THE UPWARD MOTION AND MOISTURE INCREASE SIGNAL...-SN
CHANCES MOVE QUICKLY BACK INTO THE FCST AREA TUE AFTERNOON. WITH THE
TIGHTER MODEL CONSENSUS...RAISED -SN CHANCES INTO THE 40-60 PERCENT
RANGE FOR TUE NIGHT...WITH 1 TO 2 INCHES OF LIGHT SNOW LOOKING
LIKELY FOR MUCH OF THE FCST AREA CHRISTMAS EVE NIGHT. USED A BLEND
OF THE NUMERICAL TEMPS GUIDANCE FOR HIGHS/LOWS MON-TUE NIGHT.
FOR CHRISTMAS DAY THROUGH SATURDAY.../DAYS 4 TO 7/...
21.00S AND 21.12Z MEDIUM RANGE MODELS IN DECENT AGREEMENT FOR A
RATHER VIGOROUS SHORTWAVE TROUGH TO BE MOVING ACROSS THE UPPER
MIDWEST ON WED WITH AN INCREASING SIGNAL FOR A SECONDARY SHORTWAVE
TO DROP ACROSS THE REGION WED NIGHT. GOOD CONSENSUS FOR BROAD
LONGWAVE TROUGHING TO REMAIN OVER CENTRAL/EASTERN NOAM FRI/SAT...
WITH PLENTY OF DIFFERENCES ON SMALLER SCALE SHORTWAVES EMBEDDED IN
THE FLOW. SOME CONSENSUS FOR A STRONGER/TRACKABLE SHORTWAVE TROUGH
TO BE DROPPING INTO THE NORTHERN PLAINS SAT. ALL IN ALL...DAY 4-7
FCST IS AVERAGE.
LIGHT SNOW REMAINS IN THE FCST FOR CHRISTMAS DAY/WED NIGHT. THE MAIN
LOWER LEVEL THERMO-DYNAMIC FORCING AND DIVERGENCE ALOFT FROM THE TUE
NIGHT SHORTWAVE WILL BE PASSING EAST OF THE AREA WED MORNING...WITH
DECREASING -SN CHANCES THRU THE DAY. GFS/ECMWF THEN DROP A RATHER
VIGOROUS SECONDARY SHORTWAVE SOUTHEAST ACROSS THE AREA WED NIGHT
WITH ANOTHER ROUND OF STRONGER DIVERGENCE/LIFT ALOFT. SOUNDINGS/X-
SECTIONS SHOWING PLENTY OF MOISTURE IN THE COLUMN FOR THIS LIFT TO
WRING OUT SOME -SN...EVEN WITH LESSER LOW LEVEL SUPPORT/LIFT AND
LOWER OVERALL PW VALUES. APPEARS THE AREA GETS A BREAK FROM THE
PRECIP/-SN BY LATER THU AND FOR FRI AS HGTS RISE A BIT AND A
LARGER/DRY/COLD SFC HIGH PRESSURE RIDGE BUILDS ACROSS THE REGION.
THIS HIGH MOVES EAST RATHER QUICKLY FRI. A MDT/STRONG ROUND OF LOWER
LEVEL WARM ADVECTION TO SPREAD INTO/ACROSS THE AREA LATER FRI THRU
SAT...AHEAD OF THE NEXT STRONGER SFC-MID LEVEL TROUGH PROGGED TO
DROP INTO THE NORTHERN PLAINS. LOWER LEVEL MOISTURE INCREASE IN THIS
FLOW APPEARS DELAYED INTO FRI NIGHT/SAT. MAY YET NEED A -SN CHANCE
AGAIN BY SAT BUT WILL STAY WITH THE DRY MODEL/ENSEMBLE CONSENSUS FOR
NOW UNTIL A CLEARER SIGNAL IS SEEN. TEMPS TO REMAIN BELOW NORMAL FOR
WED-SAT WITH THE AREA UNDER THE NORTHWEST FLOW ALOFT. SOME WELL
BELOW NORMAL TEMPS WITH THE LARGER/COLD HIGH FOR THU/FRI. MODEL/
ENSEMBLE CONSENSUS FOR HIGHS/LOWS IN THE WED-SAT PERIOD LOOKS TO
HAVE THIS WELL TRENDED.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1128 PM CST SAT DEC 21 2013
THE MAIN FOCUS IS ON THE SNOW THAT WILL MOVE IN TONIGHT AND HOW
LOW CONDITIONS WILL GET. FLIGHT CONDITIONS ARE CURRENTLY
MVFR...BUT WILL DROP TO IFR ONCE THE SNOW BEGINS SHORTLY AFTER
MIDNIGHT. LSE HAS THE HIGHER CHANCE OF SEEING THE LOWER VISIBILITY
SNOW WITH THE MAIN BAND OF HEAVY SNOW TRACKING THROUGH SOUTHWEST
WISCONSIN. VISIBILITIES ARE CURRENTLY IN THE HALF TO 2 MILE RANGE
DOWN IN IOWA UPSTREAM FROM LSE. EXPECT THAT THE MAIN TIME FRAME
FOR SEEING THE HEAVIER SNOW WILL BE BETWEEN 11-14Z WITH THE
MODERATE SNOW ENDING BY LATE MORNING. SOME LIGHT SNOW LOOKS LIKE
IT WILL HOLD ON THROUGH THE AFTERNOON AND EVENING HOURS AT
LSE/RST...SO KEPT CEILINGS DOWN THROUGH THE REST OF THE PERIOD.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR WIZ034-041-042-
053.
WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR WIZ043-044-054-
055-061.
MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR MNZ096.
IA...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR IAZ010-011-019.
WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR IAZ029-030.
&&
$$
UPDATE...HALBACH
SHORT TERM...RRS
LONG TERM....RRS
AVIATION...HALBACH
AREA FORECAST DISCUSSION
NWS PUEBLO CO
341 AM MST SUN DEC 22 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 325 AM MST SUN DEC 22 2013
CURRENTLY...
LIGHT SNOW SHOWERS WERE NOTED OVER THE S MTNS/GREATER I-25 CORRIDOR
REGION EARLY THIS MORNING. ELSEWHERE...KALS WAS REPORTING DENSE FOG
ALTHOUGH THE KALS AIRPORT WEB CAMS WERE NOT SHOWING MUCH IN THE WAY
OF FOG AT 2 AM. OTHERWISE...SKIES OVER MOST OF THE REGION WERE
MOSTLY CLOUDY...WITH MAINLY MID LVL CLOUDIENESS.
TODAY...
LIGHT SNOW OVER THE S MTNS/I-25 CORRIDOR REGION WILL DECREASE
TOWARDS SUNRISE WITH CLOUDS GRADUALLY DECREASING LATER THIS MORNING.
IT WILL BE A COOL DAY ACROSS THE REGION WITH HIGHS GENERALLY IN THE
30S ACROSS THE PLAINS...AND MAINLY TEENS AND 20S MOUNTAINS/VALLEYS.
SNOW OVER THE C MTNS WILL DECREASE AND DO NOT EXPECT ANY SIGNIF
ACCUMS THIS MORNING AND EARLY AFTERNOON. BY LATER TODAY...ANOTHER
DISTURBANCE IN THE NW FLOW WILL MOVE TOWARDS THE C MTNS AND SNOW
WILL ONCE AGAIN PICK UP...MAINLY ON THE NW SLOPES.
TONIGHT...
SNOW IS LIKELY OVER THE C MTNS...ESPECIALLY N OF COTTONWOOD PASS.
HEAVIEST ACCUMS...A FEW INCHES..WILL BE LIKELY. WITH THE JET MOVING
BACK OVER THE REGION...WINDS AT THE HIGHER ELEVATIONS WILL BE
PICKING UP OVER THE MTNS...AND EXPECT WE WILL SEE SOME GUSTS INTO
THE 40+ MPH RANGE...ESPECIALLY OVER THE C MTNS...PIKES PEAK AND S
MTNS. TRAVEL ACROSS THE C MTN PASSES WILL BE A BIT TRICKY DUE TO THE
BLOWING AND FALLING SNOW. TEMPS TONIGHT SHOULD BE A FEW DEGREEES
COLDER THAN SUN MORNINGS LOWS AS CLEAR SKIES SHOULD ALLOW FOR BETTER
RADIATIONAL COOLING. THE SAN LUIS VALLEY WILL BE QUITE COLD WITH
LOWS AOA -10F. /HODANISH
.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 325 AM MST SUN DEC 22 2013
...A DRY WEEK AHEAD...
OVERALL WX PATTERN CONTINUES TO LOOK PRETTY DRY FOR THE REMAINDER
OF 2013. FIRST FEW DAYS OF THE COMING WEEK WE WILL BE UNDER NW FLOW
ALOFT...AND A COUPLE WEAK SHORT WAVES WILL BRING THE CHANCE OF A FEW
SHSN FOR THE MTS OF LAKE AND CHAFFEE COUNTY...BUT THE REMAINDER OF
SERN CO LOOKS DRY. THE ECMWF IS STILL PROGGING SOME LIGHT QPF WITH
THE SHORTWAVE ARRIVING ON TUE...BUT EVEN THE EC HAS BACKED OFF
PREVIOUS FORECASTS...AND THE NAM AND GFS ARE COMPLETELY DRY SAVE FOR
THE LIGHT SHOWERS OVER THE DVD. HAVE LOWERED POPS TO NEAR ZERO FOR
THE REMAINDER OF OUR CWA...SO THERE WILL NOT BE A WHITE CHRISTMAS
THIS YEAR. MAIN IMPACT FROM THIS SYSTEM WILL BE TO BRING SLIGHTLY
COOLER WX TO OUR AREA FOR CHRISTMAS.
A BROAD UPPER RIDGE WILL REBUILD THURSDAY INTO FRIDAY...AND TEMPS
OVER THE PLAINS WILL REBOUND TO THE 50S FRI INTO THE EARLY PART OF
NEXT WEEKEND...AS H7 TEMPS RISE ABOVE ZERO E OF THE MTS. COULD EVEN
SEE SOME 60 DEGREE TEMPS IF THE RIDGE FLATTENS A BIT MORE. POPS
REMAIN NR ZERO FOR THIS LATTER PART OF THE WEEK...EVEN OVER THE MTS.
THE ECMWF AND GFS THEN DIVERGE FOR THE BALANCE OF NEXT WEEKEND INTO
THE NEW YEARS. THE EC BRINGS A WEAK UPPER LOW OVER OUR AREA NEXT
SUNDAY...FOLLOWED BY THE RETURN OF NW FLOW AND DRY CONDITIONS. THE
GFS SPLITS THE FLOW...LEAVING US MOSTLY DRY SUNDAY...BUT THEN PHASES
THE TWO STREAMS BY NEW YEARS...POSSIBLY BRINGING US SOME SNOW TO
START OFF 2014. LOW POPS IN THE ENSEMBLE GRIDS LOOK ON TARGET FOR
NOW. ROSE
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 325 AM MST SUN DEC 22 2013
KCOS...MAY SEE A SNOWFLAKE OR TWO THIS MORNING PRODUCING BRIEF
MVFR...BUT OVERALL EXPECT VFR CONDITIONS NEXT 24H. HRRR WIND FIELDS
SHOWING A DIURNAL REGIME SHOOULD SET UP BY LATER TODAY.
KPUB...MAY SEE BRIEF MVFR CIGS THIS MORNING...OTHERWISE VFR NEXT 24H.
KALS...PATCHY DENSE GROUND FOG LIKELY AT KCOS THIS MORNING. FOG/LOW
CLOUDS SHOULD DISSIPATE BY LATE MORNING. NOTICEABLY DRIER AIR JUST
OFF THE SURFACE IS EXPECTED TO MOVE INTO THE VALLEY LATE THIS
AFTERNOON AND THIS SHOULD DECREASE THE CHANCE OF LOW CLOUDS FORMING
LATER TONIGHT. HOWEVER...LOCALLY DENSE GROUND FOG WILL BE POSSIBLE.
SNOW SHOWERS WILL BE POSSIBLE OVER HE C MTNS TODAY. SNOW AND WIND
WILL PICK UP OVER THE C MTNS LATE THIS AFTERNOON INTO TONIGHT.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...HODANISH
LONG TERM...ROSE
AVIATION...HODANISH
AREA FORECAST DISCUSSION
NWS ALBANY NY
956 AM EST SUN DEC 22 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT FROM CENTRAL NEW YORK TO THE MAINE COAST
WILL SHIFT SLIGHTLY AS A STORM MOVES ALONG IT TODAY. NORTH OF IT
IT WILL BE CHILLY WITH RAIN AND FREEZING RAIN...WITH RAIN AND VERY
MILD WEATHER TO ITS SOUTH. THE STORM WILL DRAG A COLD FRONT
THROUGH THE REGION TONIGHT AND THEN SLIDE SLOWLY OFFSHORE MONDAY.
HIGH PRESSURE WILL BUILD FROM ONTARIO INTO NEW YORK TUESDAY INTO
CHRISTMAS...WITH MUCH COLDER AIR FILTERING INTO THE REGION. THE
WEEK WILL END WITH A SERIES OF FAST MOVING WEATHER SYSTEMS WITH
BOUTS OF SNOW SHOWERS AND GENERALLY SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 930 AM...HIGHLY VARIABLE CONDITIONS PERSIST ACROSS THE
FORECAST AREA. TEMPS ARE IN THE UPPER 20S TO LOWER 30S FROMT THE
LAKE GEORGE SARATOGA REGION INTO THE CAPITAL DISTRICT...IN THE UPPER
30S TO LOWER 40S IN THE MOHAWK VALLEY AND THE VALLEYS OF SOUTHERN
VERMONT...AND IN THE 50S TO MID 60S ELSEWHERE. EVENTUALLY EXPECT THE
WARM AIR TO ARRIVE IN ALL LOCATIONS...BUT FOR NOW HAVE ADJUSTED THE
HOURLY TEMPS/DEWPOINTS TO REFLECT CURRENT CONDITIONS. IF TEMPS DO
NOT RISE IN THE LAKE GEORGE SARATOGA REGION SOON...MAY NEED TO
EXTEND THE FREEZING RAIN ADVISORY A LITTLE LONGER.
.PREVIOUS DISCUSSION...
AS OF 635 AM EST...WIDE VARIETY OF TEMPERATURES ACROSS THE REGION
THIS MORNING WITH STALLED FRONTAL BOUNDARY SITUATED DIRECTLY
ACROSS THE CENTRAL PORTION OF THE CWA. NORTH OF THE
BOUNDARY...VERY COLD CANADIAN AIR IS BEING PULLED SOUTHWARD THANKS
TO A LOW LEVEL NNE FLOW THROUGH THE CHAMPLAIN VALLEY AND INTO THE
HUDSON VALLEY REGION. THIS HAS ALLOWED TEMPS TO DROP BELOW
FREEZING FOR THE GLENS FALLS AND SARATOGA SPRINGS AREA. TEMPS HAVE
FALLEN INTO THE LOW TO MID 30S IN THE CAPITAL REGION.
AT THE SAME TIME...VERY WARM TEMPS ALOFT ARE IN PLACE THANKS TO A
STRONG SOUTHERLY FLOW. AS A RESULT...SOME OF THE WARMER TEMPS AT THIS
HOUR ARE ACROSS THE MOUNTAIN PEAKS OF THE CATSKILLS...SRN GREENS
AND BERKSHIRES...WHERE TEMPS ARE WELL INTO THE 50S. ALSO...A
SOUTHERLY LOW LEVEL WIND COMING UP THE MID HUDSON VALLEY HAS
ALLOWED SOME WARMER AIR TO MOVE TOWARDS POUGHKEEPSIE AND
HUDSON...WITH SFC TEMPS HAVING JUMPED UP INTO THE LOW 60S! THE
JUST LAUNCHED 12Z KALY SOUNDING SHOWS THE COLD SFC LAYER IS ONLY
ABOUT 200 METERS THICK...WITH A WARM NOSE OF ABOUT +16 C AT 850 HPA.
WITH AN APPROACHING LOW PRESSURE AREA AND THE SFC BOUNDARY IN
PLACE...OVERRUNNING PRECIP HAS MOVED TO THE NORTH OF THE
REGION...FALLING AS FZRA/PL ACROSS THE BTV CWA. RIGHT NOW...MUCH
OF OUR CWA IS IN A DRY SLOT...WITH JUST SOME SPOTTY FREEZING RAIN
ACROSS THE SOUTHEASTERN ADIRONDACKS...AND SOME LIGHT RAIN SHOWERS
ACROSS WESTERN NEW ENGLAND. THE LATEST 08Z 3KM HRRR SHOWS THIS DRY
SLOT SHOULD START TO FILL IN TOWARDS THE MID MORNING AS THE LOW
PRESSURE AREA MOVES NORTHEAST ACROSS THE OHIO VALLEY AND
EVENTUALLY TOWARDS UPSTATE NY. RIGHT NOW...WE WILL HOLD CHC POPS
FOR THE NEXT FEW HOURS ACROSS CENTRAL/SOUTHERN PARTS OF THE
AREA...WITH LIKELY/CATEGORICAL POPS ACROSS THE FAR NORTH NEAR THE
BTV CWA BORDER. BY THE LATE MORNING...WE WILL RISE POPS TO
LIKELY/CATEGORICAL FOR WESTERN AND CENTRAL PARTS OF THE CWA AS
WELL.
FOR NOW...IT DOESN/T APPEAR THAT THE CAPITAL REGION WILL BE SEEING
ANY MEASUREABLE FREEZING RAIN...AS THE APPROACHING STORM SHOULD
ALLOW THE STALLED BOUNDARY TO START TO MOVE NORTHWARD AS A WARM
FRONT...AND BRING THE ALBANY AREA INTO THE WARM SECTOR ONCE THE
NEXT ROUND OF RAINFALL BEGINS. ALTHOUGH THERE MAY BE A SPOTTY
SPRINKLE BEFORE THAT OCCURS...IT SHOULDN/T BE ABLE TO ACCRETE MUCH
ICE AT ALL WITH MARGINAL TEMPS AND AN ALREADY WET GROUND.
STILL...WE HAVE PASSED ALONG THE MESSAGE THROUGH OUR SOCIAL MEDIA
CHANNELS THAT WITH TEMPS NEAR FREEZING...SOME WET SURFACES COULD
POTENTIALLY BE SLICK...ALTHOUGH THIS WILL LIKELY BE RATHER SPOTTY.
BASED ON WHATS HAPPENING AT KPOU/1B1...THIS WARMER AIR IS ON THE
MOVE...AND SHOULD WIN OUT OVER THE COLD AIR IN THE CAPITAL REGION
AS THE STRONG STORM SYSTEM MOVES TOWARDS OUR AREA FAIRLY SOON.
HOWEVER...FURTHER NORTH ACROSS THE LAKE GEORGE AREA...IT MAY TAKE
UNTIL THE MID TO LATE MORNING FOR THE WARM FRONT TO MOVE THROUGH
AND TEMPS TO WARM UP. AS A RESULT...A PROLONGED PERIOD OF FREEZING
RAIN CAN BE EXPECTED ACROSS THE LAKE GEORGE SARATOGA REGION. ICE
ACCRETION AMOUNTS WILL RANGE FROM A TRACE TO A TENTH ACROSS THE
SARATOGA SPRINGS AREA TO A FEW TENTHS FOR GLENS FALLS TO ABOUT
FOUR TENTHS ACROSS THE NORTH END OF LAKE GEORGE. ASIDE FROM SOME
HAZARDOUS DRIVING CONDITIONS...THIS MAY LEAD TO SOME ISOLATED
POWER OUTAGES.
AREAS IN THE WARM SECTOR SHOULD SEE SFC TEMPS WARM
SIGNIFICANTLY...AS THOSE WARMER TEMPS ALOFT ARE MIXED IN THE
BOUNDARY LAYER. MAX TEMPS LOOK TO REACH INTO THE 50S ACROSS MUCH OF
THE CENTRAL AND SOUTHERN PARTS OF THE AREA...WITH SOME MID 60S FOR
THE MID HUDSON VALLEY.
WHILE IT WILL RAIN DURING THE MID TO LATE MORNING HOURS...MOST AREAS
WILL BE DONE SEEING PRECIPITATION BY THE EARLY TO MID AFTN
HOURS...AS THE STORM/S COLD FRONT PASSES THROUGH THE AREA. TOTAL
RAINFALL FOR SUNDAY WILL RANGE FROM JUST A QUARTER OF AN INCH
ACROSS LITCHFIELD COUNTY CT...TO AROUND THREE QUARTERS OF AN INCH
IN THE CAPITAL REGION TO ABOUT AN INCH AND A HALF OVER THE
ADIRONDACKS. SEE THE HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL
TO AFFECT AREA RIVERS AND STREAMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
FOR THIS PERIOD THE MODEL SUITE (GEM/GFS/ECMWF) ARE IN FAIRLY
GOOD AGREEMENT. DURING THE THIS EVENING THE SFC LOW AND ITS UPPER
DYNAMICS WILL LIFT NE OUT OF FCA. A SERIES OF 500HPA SHORT WAVES
WILL DIG A TROF OVER GRTLKS...MAINTAINING A STRONG SW 500HPA FLOW
OVER THE EASTERN THIRD OF THE NATION. FOR A TIME THIS WILL ACT TO
WEAKEN THE SFC LOW FURTHER OVER NEW ENG...BUT THE SFC LOW WILL
DRAG A CDFNT THROUGH THE REGION TNGT. GIVEN THE UPPER FLOW COOLER
AIR WILL BE SLOW TO FILTER IN OVERNIGHT....AND TEMPS WILL REMAIN
ABV FREEZING IN MOST AREAS...WITH SNOW MELT CONTINUING.
BY MONDAY THIS CDFNT WILL NEARLY STALL ALONG THE EASTERN
SEABOARD...AND WITH DIGGING 500HPA TROF INTERACTING WITH THE COASTAL
BAROCLINIC ZONE WILL TRIGGER A BOUT OF OVERRUNINNG RAIN...ALONG THE
I-95 CORRIDOR THAT WILL BACK BUILD INTO SE PORTIONS OF FCA. QPF
DURING MONDAY WITH THIS SHOULD BE 0.25 TO 0.50 IN THESE AREAS...AND
GIVEN THESE AREAS WERE IN THE WARM SECTOR MUCH OF THE CURRENT
EVENT...THEY MELTED MOST OF THEIR SNOW...BUT HAD LITTLE RAINFALL.
ADD TO THAT THE 2-3 DAYS THIS OCCURRED...THE ADDITIONAL RAIN IN
SOUTHEAST AREAS MONDAY SHOULD NOT RESULT IN ANYTHING OTHER THAN
WITHIN BANK RISES.
FURTHER WEST MONDAY AS HIGH PRESSURE BUILDS EAST WIND GRADIENT
WILL INCR AND AS THE 500HPA TROF PUSHES EAST A MUCH STRONGER 2NDRY
CDFNT WILL PUSH INTO THE REGION LATE MONDAY AND THROUGH MONDAY
NIGHT. TEMPS MONDAY WILL HOLDS STEADY THEN FALL DURING THE AFTN.
MONDAY NIGHT INTO TUES THE PASSAGE OF THE 500HPA TROF...CAA WILL
RESULT IN SCT -SHSN ACTIVITY. HWVR LLVL FLOW WILL BE TOTALLY
UNFAVORABLE FOR LK EFFECT OVER EASTERN NY.
ONCE THE 500HPA TROF EXITS CHRISTMAS EVE BOTH A 500HPA RIDGE...AND
SFC HIGH PRESSURE WILL SETTLE OVER NYS AND MID ATLC REGION. THIS
WILL SET THE STAGE FOR A FRIGID NIGHT WITH IDEAL RADIATIONAL
COOLING...ONE OF THE LONGEST NIGHTS OF THE YEAR...CLEAR SKIES AND
DRY AIR MASS. LOWS WILL PLUNGE TO -20F IN PARTS OF THE ADIRONDACKS
TO AROUND 10 IN THE SE.
TEMPS WILL RECOVER CHRISTMAS DAY TO THE TEENS AND 20S AS SFC HIGH
SLIDES OFFSHORE. SOME CLOUDS MAY ARRIVE IN THE AFTERNOON AS NEXT
WEAK SYSTEM APPROACHES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE EFP WILL FEATURE A SERIES OF FAST MOVING SYSTEMS IN W-NW FLOW.
MOST WILL BE FAIRLY WK CDFNTS AND/OR 500HPA SHORT WVS...WHICH
WILL INCR CLOUDS AND PRODUCE SCT -SHSN AND AT TIMES HAVE SOME
INTERACTION WITH THE GRTLKS. TEMPS WILL RETURN TO NEAR NORMALS
AFTER A FRIGID CHRISTMAS. TYPICAL WINTER IN UPSTATE NY.
CHRISTMAS NIGHT AND THURS THE FIRST OF THESE SYSTEMS RACES ACROSS
ONTARIO...WITH A FEW WEAK FRONTS AND A 500HPA SHORT WV. MAIN
IMPACTS WILL INCR CLOUDS MAINLY N & W. THU NT IT WILL DRAG A
CDFNT THROUGH WITH SOME -SHSN ACTIVITY MAINLY N & WEST. IN ITS
WAKE FRI CAA AND A 2NDARY CDFNT AND NW FLOW WILL TRIGGER SCT -SHSN
WITH SOME LK ASSISTANCE. WK SFC HIGH BUILDS OVER FCA FRI NT.
SAT ANOTHER WK SHORT WV AND SFC SYSTEM MOVES THROUGH THE GRTLKS
WITH A LITTLE WAA INCRG CLOUDS AND SCT -SHSN IN ECMWF...GETTING SOME
ASSIST FM THE LKS. GFS HAS MORE CLOUDS AND A WIDESPREAD LT -SN OF
MAYBE AN INCH. SAT NT INTO SUN FLOW BCMS ZONAL TO WSW AT 500HPA.
WMFNT AND SFC LOW SETS UP N OF RGN.
NOT MUCH DIFFERENCE BWTN GFS AND ECMWF. WILL POPULATE WITH HPC MID
SHIFT AND TWEAK POPS A TAD. OTHERWISE A QUIET PERIOD FOR THE
HOLIDAY WEEK.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A FRONTAL BOUNDARY WILL BE OVER UPSTATE NY AND NEW ENGLAND TODAY
WITH AREAS OF LOW PRESSURE MOVING ALONG IT. THIS BOUNDARY WILL
DIVIDE VERY COLD AIR FROM UNSEASONABLY MILD AIR OVER THE E-CNTRL NY
CORRIDOR WITH SOME FREEZING RAIN CONTINUING FOR KGFL INTO THE LATE
MORNING...AND SOME SCT SHOWERS FROM KALB-KPSF SOUTHWARD LATE THIS
MORNING INTO THE AFTERNOON. THE BOUNDARY WILL CONTINUE TO LIFT
NORTH...AS A WARM FRONT RAPIDLY THIS MORNING.
FLIGHT CONDITIONS VARY FROM LIFR/IFR AT KGFL/KALB/KPSF TO VFR/MVFR
AT KPOU THIS MORNING. CONDITIONS WILL IMPROVE TO VFR LEVELS AT KPOU
WITH BETTER MIXING...AS THE FRONTAL BOUNDARY LIFTS NORTHWARD. SOME
PATCHY MVFR MIST MAY BE AROUND IN THE LATE MORNING THERE. FURTHER
NORTH...IFR/MVFR CONDITIONS WILL PERSIST INTO THE AFTERNOON WITH
LIGHT FREEZING RAIN TRANSITIONING TO RAIN AT KGFL AT 16Z. MOST OF
THE FLIGHT CONDITIONS THIS AFTERNOON MAY BE IN THE MVFR RANGE...AS
THE FRONT LIFTS NORTH OF ALL THE TERMINALS. SOME DRIZZLE SHOULD
LINGER INTO THIS EVENING...WHICH MAY ALLOW FOR MVFR OR BRIEF PERIODS
OF IFR CIGS/VSBYS AT ALL THE TAF SITES...EXCEPT FOR KALB WHERE LOW
VFR LOOKS POSSIBLE. THE CIGS MAY START TO RISE AROUND MIDNIGHT WITH
SOME DRIER AIR STARTING TO FILTER IN FROM THE SOUTHWEST.
LOW LEVEL WIND SHEAR WILL BE A PROBLEM THIS MORNING AT ALL THE TAF
SITES WITH 2 KFT AGL WINDS FROM THE S/SW AT 45-60 KTS. THE LOW
LEVEL WIND SHEAR LOOKS TO LAST INTO THE EARLY TO MID AFTERNOON AT
THE TERMINALS. THE LOW LEVEL JET STARTS TO LIFT NORTH AND EAST AT
THAT TIME. AT THE SFC...THE WINDS WILL VEER FROM THE EAST OR
NORTHEAST AT KGFL/KALB TO THE SOUTH AT 8-15 KTS WITH SOME GUSTS
CLOSE TO 25 KTS AT KALB AND KPOU. THE WINDS WILL DECREASE FROM THE
S/SW AT LESS THAN 10 KTS AFTER 00Z/MON.
OUTLOOK...
MONDAY: LOW OPERATIONAL IMPACT. CHANCE OF -SHRAS.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THOUGH TONIGHT WITH
INCREASING SNOW MELT. LOW PRESSURE WILL MOVE ALONG A NEARLY
STATIONARY FRONT FROM THE NIAGARA FRONTIER TO NEW ENGLAND BY THIS
EVENING. 1-2 INCHES OF ADDITIONAL RAINFALL IS EXPECTED IN THE
ADIRONDACKS...WITH LESSER AMOUNTS SOUTH. TEMPERATURES TODAY WILL WARM
INTO THE 50S AND 60S REMAIN ABOVE FREEZING TONIGHT.
IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT
SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF
INCH...BUT ALMOST ALL THE SNOW WILL MELT. EVEN AS THE RAIN TAPERS
OFF THIS EVENING...SNOW MELT AND RUNOFF WILL CONTINUE TONIGHT.
IN THE SOUTH THE RAINFALL WILL BE SUFFICIENT FOR SIGNIFICANT
WITHIN BANK RISES...BUT FLOODING IS NOT EXPECTED AT THIS TIME.
THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK
VALLEY INTO THE ADIRONDACKS WHERE 1 TO 2 INCHES ADDITIONAL RAIN
AND UP TO AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED.
FLOOD WATCHES REMAIN IN EFFECT THROUGH TONIGHT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR
NYZ041>043-083-084.
FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ032-033-038>040-042-
043-082.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...GJM/FRUGIS
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...WASULA
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS ALBANY NY
652 AM EST SUN DEC 22 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT FROM CENTRAL NEW YORK TO THE MAINE COAST
WILL SHIFT SLIGHTLY AS A STORM MOVES ALONG IT TODAY. NORTH OF IT
IT WILL BE CHILLY WITH RAIN AND FREEZING RAIN...WITH RAIN AND VERY
MILD WEATHER TO ITS SOUTH. THE STORM WILL DRAG A COLD FRONT
THROUGH THE REGION TONIGHT AND THEN SLIDE SLOWLY OFFSHORE MONDAY.
HIGH PRESSURE WILL BUILD FROM ONTARIO INTO NEW YORK TUESDAY INTO
CHRISTMAS...WITH MUCH COLD AIR FILTERING INTO THE REGION. THE
WEEK WILL END WITH A SERIES OF FAST MOVING WEATHER SYSTEMS WITH
BOUTS OF SNOW SHOWERS AND GENERALLY SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 635 AM EST...WIDE VARIETY OF TEMPERATURES ACROSS THE REGION
THIS MORNING WITH STALLED FRONTAL BOUNDARY SITUATED DIRECTLY
ACROSS THE CENTRAL PORTION OF THE CWA. NORTH OF THE
BOUNDARY...VERY COLD CANADIAN AIR IS BEING PULLED SOUTHWARD THANKS
TO A LOW LEVEL NNE FLOW THROUGH THE CHAMPLAIN VALLEY AND INTO THE
HUDSON VALLEY REGION. THIS HAS ALLOWED TEMPS TO DROP BELOW
FREEZING FOR THE GLENS FALLS AND SARATOGA SPRINGS AREA. TEMPS HAVE
FALLEN INTO THE LOW TO MID 30S IN THE CAPITAL REGION.
AT THE SAME TIME...VERY WARM TEMPS ALOFT ARE IN PLACE THANKS TO A
STRONG SOUTHERLY FLOW. AS A RESULT...SOME OF THE WARMER TEMPS AT THIS
HOUR ARE ACROSS THE MOUNTAIN PEAKS OF THE CATSKILLS...SRN GREENS
AND BERKSHIRES...WHERE TEMPS ARE WELL INTO THE 50S. ALSO...A
SOUTHERLY LOW LEVEL WIND COMING UP THE MID HUDSON VALLEY HAS
ALLOWED SOME WARMER AIR TO MOVE TOWARDS POUGHKEEPSIE AND
HUDSON...WITH SFC TEMPS HAVING JUMPED UP INTO THE LOW 60S! THE
JUST LAUNCHED 12Z KALY SOUNDING SHOWS THE COLD SFC LAYER IS ONLY
ABOUT 200 METERS THICK...WITH A WARM NOSE OF ABOUT +16 C AT 850 HPA.
WITH AN APPROACHING LOW PRESSURE AREA AND THE SFC BOUNDARY IN
PLACE...OVERRUNNING PRECIP HAS MOVED TO THE NORTH OF THE
REGION...FALLING AS FZRA/PL ACROSS THE BTV CWA. RIGHT NOW...MUCH
OF OUR CWA IS IN A DRY SLOT...WITH JUST SOME SPOTTY FREEZING RAIN
ACROSS THE SOUTHEASTERN ADIRONDACKS...AND SOME LIGHT RAIN SHOWERS
ACROSS WESTERN NEW ENGLAND. THE LATEST 08Z 3KM HRRR SHOWS THIS DRY
SLOT SHOULD START TO FILL IN TOWARDS THE MID MORNING AS THE LOW
PRESSURE AREA MOVES NORTHEAST ACROSS THE OHIO VALLEY AND
EVENTUALLY TOWARDS UPSTATE NY. RIGHT NOW...WE WILL HOLD CHC POPS
FOR THE NEXT FEW HOURS ACROSS CENTRAL/SOUTHERN PARTS OF THE
AREA...WITH LIKELY/CATEGORICAL POPS ACROSS THE FAR NORTH NEAR THE
BTV CWA BORDER. BY THE LATE MORNING...WE WILL RISE POPS TO
LIKELY/CATEGORICAL FOR WESTERN AND CENTRAL PARTS OF THE CWA AS
WELL.
FOR NOW...IT DOESN/T APPEAR THAT THE CAPITAL REGION WILL BE SEEING
ANY MEASUREABLE FREEZING RAIN...AS THE APPROACHING STORM SHOULD
ALLOW THE STALLED BOUNDARY TO START TO MOVE NORTHWARD AS A WARM
FRONT...AND BRING THE ALBANY AREA INTO THE WARM SECTOR ONCE THE
NEXT ROUND OF RAINFALL BEGINS. ALTHOUGH THERE MAY BE A SPOTTY
SPRINKLE BEFORE THAT OCCURS...IT SHOULDN/T BE ABLE TO ACCRETE MUCH
ICE AT ALL WITH MARGINAL TEMPS AND AN ALREADY WET GROUND.
STILL...WE HAVE PASSED ALONG THE MESSAGE THROUGH OUR SOCIAL MEDIA
CHANNELS THAT WITH TEMPS NEAR FREEZING...SOME WET SURFACES COULD
POTENTIALLY BE SLICK...ALTHOUGH THIS WILL LIKELY BE RATHER SPOTTY.
BASED ON WHATS HAPPENING AT KPOU/1B1...THIS WARMER AIR IS ON THE
MOVE...AND SHOULD WIN OUT OVER THE COLD AIR IN THE CAPITAL REGION
AS THE STRONG STORM SYSTEM MOVES TOWARDS OUR AREA FAIRLY SOON.
HOWEVER...FURTHER NORTH ACROSS THE LAKE GEORGE AREA...IT MAY TAKE
UNTIL THE MID TO LATE MORNING FOR THE WARM FRONT TO MOVE THROUGH
AND TEMPS TO WARM UP. AS A RESULT...A PROLONGED PERIOD OF FREEZING
RAIN CAN BE EXPECTED ACROSS THE LAKE GEORGE SARATOGA REGION. ICE
ACCRETION AMOUNTS WILL RANGE FROM A TRACE TO A TENTH ACROSS THE
SARATOGA SPRINGS AREA TO A FEW TENTHS FOR GLENS FALLS TO ABOUT
FOUR TENTHS ACROSS THE NORTH END OF LAKE GEORGE. ASIDE FROM SOME
HAZARDOUS DRIVING CONDITIONS...THIS MAY LEAD TO SOME ISOLATED
POWER OUTAGES.
AREAS IN THE WARM SECTOR SHOULD SEE SFC TEMPS WARM
SIGNIFICANTLY...AS THOSE WARMER TEMPS ALOFT ARE MIXED IN THE
BOUNDARY LAYER. MAX TEMPS LOOK TO REACH INTO THE 50S ACROSS MUCH OF
THE CENTRAL AND SOUTHERN PARTS OF THE AREA...WITH SOME MID 60S FOR
THE MID HUDSON VALLEY.
WHILE IT WILL RAIN DURING THE MID TO LATE MORNING HOURS...MOST AREAS
WILL BE DONE SEEING PRECIPITATION BY THE EARLY TO MID AFTN
HOURS...AS THE STORM/S COLD FRONT PASSES THROUGH THE AREA. TOTAL
RAINFALL FOR SUNDAY WILL RANGE FROM JUST A QUARTER OF AN INCH
ACROSS LITCHFIELD COUNTY CT...TO AROUND THREE QUARTERS OF AN INCH
IN THE CAPITAL REGION TO ABOUT AN INCH AND A HALF OVER THE
ADIRONDACKS. SEE THE HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL
TO AFFECT AREA RIVERS AND STREAMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
FOR THIS PERIOD THE MODEL SUITE (GEM/GFS/ECMWF) ARE IN FAIRLY
GOOD AGREEMENT. DURING THE THIS EVENING THE SFC LOW AND ITS UPPER
DYNAMICS WILL LIFT NE OUT OF FCA. A SERIES OF 500HPA SHORT WAVES
WILL DIG A TROF OVER GRTLKS...MAINTAINING A STRONG SW 500HPA FLOW
OVER THE EASTERN THIRD OF THE NATION. FOR A TIME THIS WILL ACT TO
WEAKEN THE SFC LOW FURTHER OVER NEW ENG...BUT THE SFC LOW WILL
DRAG A CDFNT THROUGH THE REGION TNGT. GIVEN THE UPPER FLOW COOLER
AIR WILL BE SLOW TO FILTER IN OVERNIGHT....AND TEMPS WILL REMAIN
ABV FREEZING IN MOST AREAS...WITH SNOW MELT CONTINUING.
BY MONDAY THIS CDFNT WILL NEARLY STALL ALONG THE EASTERN
SEABOARD...AND WITH DIGGING 500HPA TROF INTERACTING WITH THE
COASTAL BAROCLINIC ZONE WILL TRIGGER A BOUT OF OVERRUNINNG RAIN...ALONG
THE I-95 CORRIDOR THAT WILL BACK BUILD INTO SE PORTIONS OF FCA.
QPF DURING MONDAY WITH THIS SHOULD BE 0.25 TO 0.50 IN THESE
AREAS...AND GIVEN THESE AREAS WERE IN THE WARM SECTOR MUCH OF THE
CURRENT EVENT...THEY MELTED MOST OF THEIR SNOW...BUT HAD LITTLE
RAINFALL. ADD TO THAT THE 2-3 DAYS THIS OCCURRED...THE ADDITIONAL
RAIN IN SOUTHEAST AREAS MONDAY SHOULD NOT RESULT IN ANYTHING OTHER
THAN WITHIN BANK RISES.
FURTHER WEST MONDAY AS HIGH PRESSURE BUILDS EAST WIND GRADIENT
WILL INCR AND AS THE 500HPA TROF PUSHES EAST A MUCH STRONGER 2NDRY
CDFNT WILL PUSH INTO THE REGION LATE MONDAY AND THROUGH MONDAY
NIGHT. TEMPS MONDAY WILL HOLDS STEADY THEN FALL DURING THE AFTN.
MONDAY NIGHT INTO TUES THE PASSAGE OF THE 500HPA TROF...CAA WILL
RESULT IN SCT -SHSN ACTIVITY. HWVR LLVL FLOW WILL BE TOTALLY
UNFAVORABLE FOR LK EFFECT OVER EASTERN NY.
ONCE THE 500HPA TROF EXITS CHRISTMAS EVE BOTH A 500HPA RIDGE...AND
SFC HIGH PRESSURE WILL SETTLE OVER NYS AND MID ATLC REGION. THIS
WILL SET THE STAGE FOR A FRIGID NIGHT WITH IDEAL RADIATIONAL
COOLING...ONE OF THE LONGEST NIGHTS OF THE YEAR...CLEAR SKIES AND
DRY AIR MASS. LOWS WILL PLUNGE TO -20F IN PARTS OF THE ADIRONDACKS
TO AROUND 10 IN THE SE.
TEMPS WILL RECOVER CHRISTMAS DAY TO THE TEENS AND 20S AS SFC HIGH
SLIDES OFFSHORE. SOME CLOUDS MAY ARRIVE IN THE AFTERNOON AS NEXT
WEAK SYSTEM APPROACHES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE EFP WILL FEATURE A SERIES OF FAST MOVING SYSTEMS IN W-NW FLOW.
MOST WILL BE FAIRLY WK CDFNTS AND/OR 500HPA SHORT WVS...WHICH
WILL INCR CLOUDS AND PRODUCE SCT -SHSN AND AT TIMES HAVE SOME
INTERACTION WITH THE GRTLKS. TEMPS WILL RETURN TO NEAR NORMALS
AFTER A FRIGID CHRISTMAS. TYPICAL WINTER IN UPSTATE NY.
CHRISTMAS NIGHT AND THURS THE FIRST OF THESE SYSTEMS RACES ACROSS
ONTARIO...WITH A FEW WEAK FRONTS AND A 500HPA SHORT WV. MAIN
IMPACTS WILL INCR CLOUDS MAINLY N & W. THU NT IT WILL DRAG A
CDFNT THROUGH WITH SOME -SHSN ACTIVITY MAINLY N & WEST. IN ITS
WAKE FRI CAA AND A 2NDARY CDFNT AND NW FLOW WILL TRIGGER SCT -SHSN
WITH SOME LK ASSISTANCE. WK SFC HIGH BUILDS OVER FCA FRI NT.
SAT ANOTHER WK SHORT WV AND SFC SYSTEM MOVES THROUGH THE GRTLKS
WITH A LITTLE WAA INCRG CLOUDS AND SCT -SHSN IN ECMWF...GETTING SOME
ASSIST FM THE LKS. GFS HAS MORE CLOUDS AND A WIDESPREAD LT -SN OF MAYBE
AN INCH. SAT NT INTO SUN FLOW BCMS ZONAL TO WSW AT 500HPA. WMFNT
AND SFC LOW SETS UP N OF RGN.
NOT MUCH DIFFERENCE BWTN GFS AND ECMWF. WILL POPULATE WITH HPC MID
SHIFT AND TWEAK POPS A TAD. OTHERWISE A QUIET PERIOD FOR THE
HOLIDAY WEEK.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A FRONTAL BOUNDARY WILL BE OVER UPSTATE NY AND NEW ENGLAND TODAY
WITH AREAS OF LOW PRESSURE MOVING ALONG IT. THIS BOUNDARY WILL
DIVIDE VERY COLD AIR FROM UNSEASONABLY MILD AIR OVER THE E-CNTRL NY
CORRIDOR WITH SOME FREEZING RAIN CONTINUING FOR KGFL INTO THE LATE
MORNING...AND SOME SCT SHOWERS FROM KALB-KPSF SOUTHWARD LATE THIS
MORNING INTO THE AFTERNOON. THE BOUNDARY WILL CONTINUE TO LIFT
NORTH...AS A WARM FRONT RAPIDLY THIS MORNING.
FLIGHT CONDITIONS VARY FROM LIFR/IFR AT KGFL/KALB/KPSF TO VFR/MVFR
AT KPOU THIS MORNING. CONDITIONS WILL IMPROVE TO VFR LEVELS AT KPOU
WITH BETTER MIXING...AS THE FRONTAL BOUNDARY LIFTS NORTHWARD. SOME
PATCHY MVFR MIST MAY BE AROUND IN THE LATE MORNING THERE. FURTHER
NORTH...IFR/MVFR CONDITIONS WILL PERSIST INTO THE AFTERNOON WITH
LIGHT FREEZING RAIN TRANSITIONING TO RAIN AT KGFL AT 16Z. MOST OF
THE FLIGHT CONDITIONS THIS AFTERNOON MAY BE IN THE MVFR RANGE...AS
THE FRONT LIFTS NORTH OF ALL THE TERMINALS. SOME DRIZZLE SHOULD
LINGER INTO THIS EVENING...WHICH MAY ALLOW FOR MVFR OR BRIEF PERIODS
OF IFR CIGS/VSBYS AT ALL THE TAF SITES...EXCEPT FOR KALB WHERE LOW
VFR LOOKS POSSIBLE. THE CIGS MAY START TO RISE AROUND MIDNIGHT WITH
SOME DRIER AIR STARTING TO FILTER IN FROM THE SOUTHWEST.
LOW LEVEL WIND SHEAR WILL BE A PROBLEM THIS MORNING AT ALL THE TAF
SITES WITH 2 KFT AGL WINDS FROM THE S/SW AT 45-60 KTS. THE LOW
LEVEL WIND SHEAR LOOKS TO LAST INTO THE EARLY TO MID AFTERNOON AT
THE TERMINALS. THE LOW LEVEL JET STARTS TO LIFT NORTH AND EAST AT
THAT TIME. AT THE SFC...THE WINDS WILL VEER FROM THE EAST OR
NORTHEAST AT KGFL/KALB TO THE SOUTH AT 8-15 KTS WITH SOME GUSTS
CLOSE TO 25 KTS AT KALB AND KPOU. THE WINDS WILL DECREASE FROM THE
S/SW AT LESS THAN 10 KTS AFTER 00Z/MON.
OUTLOOK...
MONDAY: LOW OPERATIONAL IMPACT. CHANCE OF -SHRAS.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THOUGH TONIGHT WITH
INCREASING SNOW MELT. LOW PRESSURE WILL MOVE ALONG A NEARLY
STATIONARY FRONT FROM THE NIAGARA FRONTIER TO NEW ENGLAND BY THIS
EVENING. 1-2 INCHES OF ADDITIONAL RAINFALL IS EXPECTED IN THE
ADIRONDACKS...WITH LESSER AMOUNTS SOUTH. TEMPERATURES TODAY WILL WARM
INTO THE 50S AND 60S REMAIN ABOVE FREEZING TONIGHT.
IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT
SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF
INCH...BUT ALMOST ALL THE SNOW WILL MELT. EVEN AS THE RAIN TAPERS
OFF THIS EVENING...SNOW MELT AND RUNOFF WILL CONTINUE TONIGHT.
IN THE SOUTH THE RAINFALL WILL BE SUFFICIENT FOR SIGNIFICANT
WITHIN BANK RISES...BUT FLOODING IS NOT EXPECTED AT THIS TIME.
THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK
VALLEY INTO THE ADIRONDACKS WHERE 1 TO 2 INCHES ADDITIONAL RAIN
AND UP TO AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED.
FLOOD WATCHES REMAIN IN EFFECT THROUGH TONIGHT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR
NYZ041>043-083-084.
FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ032-033-038>040-042-
043-082.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...FRUGIS
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...WASULA
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS ALBANY NY
635 AM EST SUN DEC 22 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT FROM CENTRAL NEW YORK TO THE MAINE COAST
WILL SHIFT SLIGHTLY AS A STORM MOVES ALONG IT TODAY. NORTH OF IT
IT WILL BE CHILLY WITH RAIN AND FREEZING RAIN...WITH RAIN AND VERY
MILD WEATHER TO ITS SOUTH. THE STORM WILL DRAG A COLD FRONT
THROUGH THE REGION TONIGHT AND THEN SLIDE SLOWLY OFFSHORE MONDAY.
HIGH PRESSURE WILL BUILD FROM ONTARIO INTO NEW YORK TUESDAY INTO
CHRISTMAS...WITH MUCH COLD AIR FILTERING INTO THE REGION. THE
WEEK WILL END WITH A SERIES OF FAST MOVING WEATHER SYSTEMS WITH
BOUTS OF SNOW SHOWERS AND GENERALLY SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 635 AM EST...WIDE VARIETY OF TEMPERATURES ACROSS THE REGION
THIS MORNING WITH STALLED FRONTAL BOUNDARY SITUATED DIRECTLY
ACROSS THE CENTRAL PORTION OF THE CWA. NORTH OF THE
BOUNDARY...VERY COLD CANADIAN AIR IS BEING PULLED SOUTHWARD THANKS
TO A LOW LEVEL NNE FLOW THROUGH THE CHAMPLAIN VALLEY AND INTO THE
HUDSON VALLEY REGION. THIS HAS ALLOWED TEMPS TO DROP BELOW
FREEZING FOR THE GLENS FALLS AND SARATOGA SPRINGS AREA. TEMPS HAVE
FALLEN INTO THE LOW TO MID 30S IN THE CAPITAL REGION.
AT THE SAME TIME...VERY WARM TEMPS ALOFT ARE IN PLACE THANKS TO A
STRONG SOUTHERLY FLOW. AS A RESULT...SOME OF THE WARMER TEMPS AT THIS
HOUR ARE ACROSS THE MOUNTAIN PEAKS OF THE CATSKILLS...SRN GREENS
AND BERKSHIRES...WHERE TEMPS ARE WELL INTO THE 50S. ALSO...A
SOUTHERLY LOW LEVEL WIND COMING UP THE MID HUDSON VALLEY HAS
ALLOWED SOME WARMER AIR TO MOVE TOWARDS POUGHKEEPSIE AND
HUDSON...WITH SFC TEMPS HAVING JUMPED UP INTO THE LOW 60S! THE
JUST LAUNCHED 12Z KALY SOUNDING SHOWS THE COLD SFC LAYER IS ONLY
ABOUT 200 METERS THICK...WITH A WARM NOSE OF ABOUT +16 C AT 850 HPA.
WITH AN APPROACHING LOW PRESSURE AREA AND THE SFC BOUNDARY IN
PLACE...OVERRUNNING PRECIP HAS MOVED TO THE NORTH OF THE
REGION...FALLING AS FZRA/PL ACROSS THE BTV CWA. RIGHT NOW...MUCH
OF OUR CWA IS IN A DRY SLOT...WITH JUST SOME SPOTTY FREEZING RAIN
ACROSS THE SOUTHEASTERN ADIRONDACKS...AND SOME LIGHT RAIN SHOWERS
ACROSS WESTERN NEW ENGLAND. THE LATEST 08Z 3KM HRRR SHOWS THIS DRY
SLOT SHOULD START TO FILL IN TOWARDS THE MID MORNING AS THE LOW
PRESSURE AREA MOVES NORTHEAST ACROSS THE OHIO VALLEY AND
EVENTUALLY TOWARDS UPSTATE NY. RIGHT NOW...WE WILL HOLD CHC POPS
FOR THE NEXT FEW HOURS ACROSS CENTRAL/SOUTHERN PARTS OF THE
AREA...WITH LIKELY/CATEGORICAL POPS ACROSS THE FAR NORTH NEAR THE
BTV CWA BORDER. BY THE LATE MORNING...WE WILL RISE POPS TO
LIKELY/CATEGORICAL FOR WESTERN AND CENTRAL PARTS OF THE CWA AS
WELL.
FOR NOW...IT DOESN/T APPEAR THAT THE CAPITAL REGION WILL BE SEEING
ANY MEASUREABLE FREEZING RAIN...AS THE APPROACHING STORM SHOULD
ALLOW THE STALLED BOUNDARY TO START TO MOVE NORTHWARD AS A WARM
FRONT...AND BRING THE ALBANY AREA INTO THE WARM SECTOR ONCE THE
NEXT ROUND OF RAINFALL BEGINS. ALTHOUGH THERE MAY BE A SPOTTY
SPRINKLE BEFORE THAT OCCURS...IT SHOULDN/T BE ABLE TO ACCRETE MUCH
ICE AT ALL WITH MARGINAL TEMPS AND AN ALREADY WET GROUND.
STILL...WE HAVE PASSED ALONG THE MESSAGE THROUGH OUR SOCIAL MEDIA
CHANNELS THAT WITH TEMPS NEAR FREEZING...SOME WET SURFACES COULD
POTENTIALLY BE SLICK...ALTHOUGH THIS WILL LIKELY BE RATHER SPOTTY.
BASED ON WHATS HAPPENING AT KPOU/1B1...THIS WARMER AIR IS ON THE
MOVE...AND SHOULD WIN OUT OVER THE COLD AIR IN THE CAPITAL REGION
AS THE STRONG STORM SYSTEM MOVES TOWARDS OUR AREA FAIRLY SOON.
HOWEVER...FURTHER NORTH ACROSS THE LAKE GEORGE AREA...IT MAY TAKE
UNTIL THE MID TO LATE MORNING FOR THE WARM FRONT TO MOVE THROUGH
AND TEMPS TO WARM UP. AS A RESULT...A PROLONGED PERIOD OF FREEZING
RAIN CAN BE EXPECTED ACROSS THE LAKE GEORGE SARATOGA REGION. ICE
ACCRETION AMOUNTS WILL RANGE FROM A TRACE TO A TENTH ACROSS THE
SARATOGA SPRINGS AREA TO A FEW TENTHS FOR GLENS FALLS TO ABOUT
FOUR TENTHS ACROSS THE NORTH END OF LAKE GEORGE. ASIDE FROM SOME
HAZARDOUS DRIVING CONDITIONS...THIS MAY LEAD TO SOME ISOLATED
POWER OUTAGES.
AREAS IN THE WARM SECTOR SHOULD SEE SFC TEMPS WARM
SIGNIFICANTLY...AS THOSE WARMER TEMPS ALOFT ARE MIXED IN THE
BOUNDARY LAYER. MAX TEMPS LOOK TO REACH INTO THE 50S ACROSS MUCH OF
THE CENTRAL AND SOUTHERN PARTS OF THE AREA...WITH SOME MID 60S FOR
THE MID HUDSON VALLEY.
WHILE IT WILL RAIN DURING THE MID TO LATE MORNING HOURS...MOST AREAS
WILL BE DONE SEEING PRECIPITATION BY THE EARLY TO MID AFTN
HOURS...AS THE STORM/S COLD FRONT PASSES THROUGH THE AREA. TOTAL
RAINFALL FOR SUNDAY WILL RANGE FROM JUST A QUARTER OF AN INCH
ACROSS LITCHFIELD COUNTY CT...TO AROUND THREE QUARTERS OF AN INCH
IN THE CAPITAL REGION TO ABOUT AN INCH AND A HALF OVER THE
ADIRONDACKS. SEE THE HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL
TO AFFECT AREA RIVERS AND STREAMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
FOR THIS PERIOD THE MODEL SUITE (GEM/GFS/ECMWF) ARE IN FAIRLY
GOOD AGREEMENT. DURING THE THIS EVENING THE SFC LOW AND ITS UPPER
DYNAMICS WILL LIFT NE OUT OF FCA. A SERIES OF 500HPA SHORT WAVES
WILL DIG A TROF OVER GRTLKS...MAINTAINING A STRONG SW 500HPA FLOW
OVER THE EASTERN THIRD OF THE NATION. FOR A TIME THIS WILL ACT TO
WEAKEN THE SFC LOW FURTHER OVER NEW ENG...BUT THE SFC LOW WILL
DRAG A CDFNT THROUGH THE REGION TNGT. GIVEN THE UPPER FLOW COOLER
AIR WILL BE SLOW TO FILTER IN OVERNIGHT....AND TEMPS WILL REMAIN
ABV FREEZING IN MOST AREAS...WITH SNOW MELT CONTINUING.
BY MONDAY THIS CDFNT WILL NEARLY STALL ALONG THE EASTERN
SEABOARD...AND WITH DIGGING 500HPA TROF INTERACTING WITH THE
COASTAL BAROCLINIC ZONE WILL TRIGGER A BOUT OF OVERRUNINNG RAIN...ALONG
THE I-95 CORRIDOR THAT WILL BACK BUILD INTO SE PORTIONS OF FCA.
QPF DURING MONDAY WITH THIS SHOULD BE 0.25 TO 0.50 IN THESE
AREAS...AND GIVEN THESE AREAS WERE IN THE WARM SECTOR MUCH OF THE
CURRENT EVENT...THEY MELTED MOST OF THEIR SNOW...BUT HAD LITTLE
RAINFALL. ADD TO THAT THE 2-3 DAYS THIS OCCURRED...THE ADDITIONAL
RAIN IN SOUTHEAST AREAS MONDAY SHOULD NOT RESULT IN ANYTHING OTHER
THAN WITHIN BANK RISES.
FURTHER WEST MONDAY AS HIGH PRESSURE BUILDS EAST WIND GRADIENT
WILL INCR AND AS THE 500HPA TROF PUSHES EAST A MUCH STRONGER 2NDRY
CDFNT WILL PUSH INTO THE REGION LATE MONDAY AND THROUGH MONDAY
NIGHT. TEMPS MONDAY WILL HOLDS STEADY THEN FALL DURING THE AFTN.
MONDAY NIGHT INTO TUES THE PASSAGE OF THE 500HPA TROF...CAA WILL
RESULT IN SCT -SHSN ACTIVITY. HWVR LLVL FLOW WILL BE TOTALLY
UNFAVORABLE FOR LK EFFECT OVER EASTERN NY.
ONCE THE 500HPA TROF EXITS CHRISTMAS EVE BOTH A 500HPA RIDGE...AND
SFC HIGH PRESSURE WILL SETTLE OVER NYS AND MID ATLC REGION. THIS
WILL SET THE STAGE FOR A FRIGID NIGHT WITH IDEAL RADIATIONAL
COOLING...ONE OF THE LONGEST NIGHTS OF THE YEAR...CLEAR SKIES AND
DRY AIR MASS. LOWS WILL PLUNGE TO -20F IN PARTS OF THE ADIRONDACKS
TO AROUND 10 IN THE SE.
TEMPS WILL RECOVER CHRISTMAS DAY TO THE TEENS AND 20S AS SFC HIGH
SLIDES OFFSHORE. SOME CLOUDS MAY ARRIVE IN THE AFTERNOON AS NEXT
WEAK SYSTEM APPROACHES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE EFP WILL FEATURE A SERIES OF FAST MOVING SYSTEMS IN W-NW FLOW.
MOST WILL BE FAIRLY WK CDFNTS AND/OR 500HPA SHORT WVS...WHICH
WILL INCR CLOUDS AND PRODUCE SCT -SHSN AND AT TIMES HAVE SOME
INTERACTION WITH THE GRTLKS. TEMPS WILL RETURN TO NEAR NORMALS
AFTER A FRIGID CHRISTMAS. TYPICAL WINTER IN UPSTATE NY.
CHRISTMAS NIGHT AND THURS THE FIRST OF THESE SYSTEMS RACES ACROSS
ONTARIO...WITH A FEW WEAK FRONTS AND A 500HPA SHORT WV. MAIN
IMPACTS WILL INCR CLOUDS MAINLY N & W. THU NT IT WILL DRAG A
CDFNT THROUGH WITH SOME -SHSN ACTIVITY MAINLY N & WEST. IN ITS
WAKE FRI CAA AND A 2NDARY CDFNT AND NW FLOW WILL TRIGGER SCT -SHSN
WITH SOME LK ASSISTANCE. WK SFC HIGH BUILDS OVER FCA FRI NT.
SAT ANOTHER WK SHORT WV AND SFC SYSTEM MOVES THROUGH THE GRTLKS
WITH A LITTLE WAA INCRG CLOUDS AND SCT -SHSN IN ECMWF...GETTING SOME
ASSIST FM THE LKS. GFS HAS MORE CLOUDS AND A WIDESPREAD LT -SN OF MAYBE
AN INCH. SAT NT INTO SUN FLOW BCMS ZONAL TO WSW AT 500HPA. WMFNT
AND SFC LOW SETS UP N OF RGN.
NOT MUCH DIFFERENCE BWTN GFS AND ECMWF. WILL POPULATE WITH HPC MID
SHIFT AND TWEAK POPS A TAD. OTHERWISE A QUIET PERIOD FOR THE
HOLIDAY WEEK.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A FRONTAL BOUNDARY WILL BE OVER UPSTATE NY AND NEW ENGLAND TODAY
WITH AREAS OF LOW PRESSURE MOVING ALONG IT. THIS BOUNDARY WILL
DIVIDE VERY COLD AIR FROM MILD AIR OVER THE E-CNTRL NY CORRIDOR WITH
SOME FREEZING RAIN CONTINUING FOR KGFL EARLY THIS MORNING...AND
OCCASIONAL LIGHT RAIN FOR KALB-KPSF SOUTHWARD BEFORE A STEADIER
RAINSHIELD MOVES IN TOWARDS 12Z.
FLIGHT CONDITIONS VARY FROM LIFR/IFR AT KGFL/KALB TO VFR/MVFR AT
KPOU AND KPSF THIS MORNING. THE TREND WILL BE FOR WIDESPREAD
IFR/MVFR CONDITIONS TO IMPACT THE TERMINALS BTWN 09Z-12Z. THE MVFR
CONDITIONS MAY CONTINUE AT KPOU UNTIL AFTER 12Z...BUT EXPECT IFR
CIGS/VSBYS FOR KGFL...KALB...KPSF THROUGH MOST OF THE LATE MORNING
INTO THE EARLY PM...AS LOW PRESSURE MOVES ACROSS CNTRL/NRN NY.
EXPECT TEMPS TO MOVE BACK ABOVE FREEZING AT KGFL AROUND 10Z.
THE RAINFALL SHOULD DIMINISH BTWN 18Z-21Z FOR THE E-CNTRL NY
TERMINALS WITH SOME SCT SHOWERS AND DRIZZLE LINGERING INTO THE EARLY
EVENING. SOME IFR/MVFR VISIBILITIES MAY PERSIST INTO THE EARLY
EVENING WITH MVFR CIGS. THE CIGS MAY START TO RISE TOWARDS MIDNIGHT
WITH SOME DRIER AIR STARTING TO FILTER IN FROM THE SOUTHWEST.
THE SFC WINDS WILL BE FROM THE E TO NE AT KALB AND KGFL EARLY THIS
MORNING AT 5-10 KTS...THEN VEER TO TO SOUTH AT AROUND 10 KTS BY 12Z
WITH SOME GUSTS AT KALB IN THE 20-25 KT RANGE. KPOU AND KPSF WILL
CONTINUE TO HAVE S/SW WINDS 5-10 KTS...THEN INCREASE TO 8-15 KTS
WITH SOME GUSTS CLOSE TO 25 KTS AT KPSF...AS THE STRONGER LLJ MOVES
IN ALOFT. THE WINDS WILL DECREASE FROM THE S/SW AT LESS THAN 10 KTS
AFTER 00Z/MON.
OUTLOOK...
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
THURSDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THOUGH TONIGHT WITH
INCREASING SNOW MELT. LOW PRESSURE WILL MOVE ALONG A NEARLY
STATIONARY FRONT FROM THE NIAGARA FRONTIER TO NEW ENGLAND BY THIS
EVENING. 1-2 INCHES OF ADDITIONAL RAINFALL IS EXPECTED IN THE
ADIRONDACKS...WITH LESSER AMOUNTS SOUTH. TEMPERATURES TODAY WILL WARM
INTO THE 50S AND 60S REMAIN ABOVE FREEZING TONIGHT.
IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT
SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF
INCH...BUT ALMOST ALL THE SNOW WILL MELT. EVEN AS THE RAIN TAPERS
OFF THIS EVENING...SNOW MELT AND RUNOFF WILL CONTINUE TONIGHT.
IN THE SOUTH THE RAINFALL WILL BE SUFFICIENT FOR SIGNIFICANT
WITHIN BANK RISES...BUT FLOODING IS NOT EXPECTED AT THIS TIME.
THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK
VALLEY INTO THE ADIRONDACKS WHERE 1 TO 2 INCHES ADDITIONAL RAIN
AND UP TO AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED.
FLOOD WATCHES REMAIN IN EFFECT THROUGH TONIGHT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR
NYZ041>043-083-084.
FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ032-033-038>040-042-
043-082.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...FRUGIS
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...WASULA
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS GRAY ME
644 AM EST SUN DEC 22 2013
.SYNOPSIS...
A COLD FRONT WILL SINK SLOWLY SOUTH TODAY AND FINALLY MOVE OFF THE
COAST LATE MONDAY. HIGH PRESSURE WILL BUILD OVER THE AREA TUESDAY
AND WEDNESDAY. HIGH PRESSURE WILL MOVE EAST OF THE REGION
THURSDAY. A COLD FRONT WILL MOVE THROUGH NORTHERN NEW ENGLAND
THURSDAY NIGHT. HIGH PRESSURE WILL BUILD OVER THE REGION THURSDAY
AND FRIDAY.
&&
.NEAR TERM /TODAY/...
645AM UPDATE...
COLD AIR IS FINALLY MAKING PROGRESS TO THE SOUTHWEST... WITH
PORTLAND NOW DOWN TO 32 DEGREES. HOWEVER... THE MAIN AREA OF
PRECIPITATION HAS SHIFTED EAST. EXPECT ANOTHER FEW ROUNDS OF RAIN
TO MOVE THROUGH... THOUGH THEY WILL BE LIGHTER THAN THE LAST
ROUND. STILL MAINTAINING CURRENT HEADLINES THOUGH THERE IS SOME
CONCERN THAT THERE COULD BE LESS TOTAL ICING ESPECIALLY IN
SOUTHWESTERN ZONES...AND MORE OF A MIX IN NORTHEAST ZONES. THE
MIDCOAST REGION AND INTERIOR AREAS LIKE AUGUSTA AND WATERVILLE
WILL LIKELY BE HARDEST HIT BY THE ICE. MEANWHILE... THE
FLIRTATIONS WITH SLEET AND SNOW CONTINUE. 12Z GYX SOUNDING HAS A
+11C LAYER AT 850 MB (THOUGH -4C JUST ABOVE THE SURFACE)... WHICH
IS VERY MUCH A FREEZING RAIN SOUNDING. HOWEVER... THE GRADIENT
JUST NORTH OF HERE IS VERY STOUT. NAM MODEL IS SHOWING THIS
WELL... BUT PROBABLY NOT EXTREME ENOUGH. SEVERAL REPORTS FROM
AUGUSTA AREA OF SLEET AND OCCASIONALLY SNOW. THE SLEET IS LOGICAL
FROM THE DEEP COLD LAYER BELOW THE WARM LAYER ALOFT... BUT THE
SNOW IS NOT AS SIMPLE TO EXPLAIN. CURRENT THINKING IS THAT ANY
SNOW IN THIS REGION IS BEING GENERATED BELOW THE ABOVE FREEZING
LAYER... FULLY WITHIN THE LOW LEVEL COLD LAYER WHICH IS JUST COLD
ENOUGH FOR SNOW FORMATION. AS A RESULT... SNOW WILL BE VERY LIGHT
DUE TO THE SHALLOW DEPTH OF THE LAYER IN WHICH IT IS BEING
GENERATED. EXPECT HEAVIER PRECIPITATION LATER IN THE DAY TO FALL
AS FREEZING RAIN OR MAYBE SLEET. HAVE PUT A LOT OF EFFORT INTO THE
HOURLY POP AND WEATHER GRIDS TO TRY TO SHOW THE PROGRESSION OF
SEVERAL WAVES OF PRECIPITATION ACROSS THE AREA TODAY... BASED
HEAVILY ON THE HRRR FORECAST.
ORIGINAL DISCUSSION...
FIRST ROUND OF HEAVIER PRECIPITATION IS MOVING EAST ACROSS
WESTERN MAINE EARLY THIS MORNING. FREEZING LINE HAS NOT MOVED
MUCH... WITH THE LINE EXISTING ROUGHLY FROM COLEBROOK TO NORTH OF
BERLIN DOWN TO LEWISTON AND OFFSHORE NEAR WISCASSET AND HAS HELD
STEADY FOR MUCH OF THE NIGHT. TO THE NORTH AND EAST OF THIS
LINE... RAIN IS FREEZING AS IT REACHES THE SURFACE. FURTHER TO THE
NORTH... A CHANGE TO SNOW HAS BEEN OBSERVED ROUGHLY FROM THE
VT/QUEBEC BORDER ACROSS NORTHERN NEW HAMPSHIRE TO SOUTH OF EUSTIS
AND SOUTH OF GREENVILLE AND OVER TO HOULTON. WITH FEW AUTOMATED
OBSERVATIONS WHICH REPORT WEATHER IN THIS REGION... CONFIDENCE IN
PRECIPITATION TYPE IS REGRETTABLY LOW. INTERPRETATION OF DUAL POL
RADAR SEEMS TO PRODUCE A VERY SIMILAR SNOW LINE TO WHAT WAS JUST
DESCRIBED... HOWEVER BECAUSE THE RADAR BEAM IS HIGH IN THIS AREA
IT IS LESS USEFUL AS A DETERMINATOR. ONE OTHER INTERESTING FACT IS
THAT BANGOR HAS BEEN REPORTING SLEET FOR SEVERAL HOURS...
OCCASIONALLY MIXING WITH SNOW. THIS SUGGESTS THAT THE COLD AIR IN
THIS AREA IS DEEP ENOUGH FOR AT LEAST SLEET... AND OCCASIONALLY
SNOW. THIS COLD AIR IS EXPECTED TO CONTINUE TO DEEPEN AND PUSH
SOUTHWARD ACROSS WESTERN MAINE TODAY AS THE CURRENT WAVE BRINGING
THE PRECIPITATION MOVES EAST. THE FOOTHILLS AND INTERIOR MIDCOAST
REGION HAS A CHANCE TO CHANGE TO SLEET OR SNOW FOR A BIT... BUT
HAVE DECIDED TO KEEP CURRENT WARNING HEADLINES IN PLACE TO AVOID
CONFUSION SINCE THE ICING HAZARD IS THE BIGGEST THREAT.
BATCH OF HEAVIER PRECIPITATION AND A FEW EMBEDDED LIGHTNING
STRIKES IS MOVING ACROSS UPSTATE NEW YORK. SOME MODELS ARE
INDICATING THIS ELEVATED CONVECTION COULD MAINTAIN ITSELF A BIT
INTO VERMONT AND NEW HAMPSHIRE AROUND 6-8 AM. HAVE INCLUDED A
CHANCE OF THUNDER IN THE FORECAST... BUT DO NOT EXPECT HEAVY OR
SEVERE THUNDERSTORMS.
EXPECT A BREAK IN THE PRECIPITATION BY AROUND 15Z... WITH ANOTHER
ROUND PROBABLY STARTING BY 18Z. BY THIS TIME... THE FREEZING LINE
WILL LIKELY HAVE SHIFTED SOUTHWEST INTO NEW HAMPSHIRE... ALLOWING
PRECIPITATION TO FALL AS FREEZING RAIN ACROSS A LARGER AREA. HAVE
A LOWER THAN AVERAGE CONFIDENCE THAT THE FREEZING LINE WILL MOVE
ALL THE WAY INTO ROCKINGHAM COUNTY OR CENTRAL MERRIMACK COUNTY...
SO HAVE INCLUDED A CHANCE OF FREEZING RAIN THERE EVEN THOUGH
HOURLY TEMPERATURES ARE ONLY FORECAST TO FALL TO 33-34 AS THERE IS
A CHANCE TEMPERATURES FALL LOWER THAN FORECAST. WILL MAINTAIN
THE STRUCTURE OF ADVISORY AND WARNING HEADLINES TODAY.
AREAS THAT WILL LIKELY BE HARDEST HIT BY ICING TODAY ARE AREAS
CURRENTLY BEING IMPACTED. THE AREA INCLUDING LEWISTON...
AUGUSTA... AND BELFAST HAVE LIKELY ALREADY SEEN SIGNIFICANT ICING
AND ARE THE MOST LIKELY AREAS TO REACH WARNING CRITERIA OF 0.5
INCHES. SOME REPORTS UP TO 1 INCH ARE POSSIBLE. AREAS FURTHER
SOUTH HAVE AN INCREASINGLY LOWER CHANCE OF REACHING THE 0.5 INCH
LEVEL AS TEMPERATURES HAVE REMAINED ABOVE FREEZING THROUGH THE
FIRST HEAVY BATCH OF RAIN.
&&
.SHORT TERM /TONIGHT AND MONDAY/...
PRECIPITATION CHANCES DECREASE TONIGHT... AND ADVISORIES AND
WARNINGS BEGIN TO EXPIRE AS THE MOST SIGNIFICANT PRECIPITATION
MOVES EAST. IN FACT... AS THE LAST WAVE MOVES EAST... SOME WARMER
AIR MAY MIX DOWN AND ALLOW MUCH OF THE NEW HAMPSHIRE TO RISE ABOVE
FREEZING AND MUCH OF MAINE TO FOLLOW SUIT MONDAY MORNING.
ON MONDAY... ANOTHER WAVE OF LOW PRESSURE TRACKS EAST ALONG THE
OFFSHORE FRONT. MODELS ARE CONSISTENT IN BRINGING PRECIPITATION
INTO COASTAL AREAS... BUT TEMPERATURES LOOK LIKELY TO BE ABOVE
FREEZING BY LATE MONDAY MORNING. HAVE EXTENDED THE ICE STORM
WARNING THROUGH NOON FOR THE COASTAL PLAIN OF MAINE AS
TEMPERATURES HERE HAVE A BETTER CHANCE OF STAYING BELOW FREEZING
AS PRECIPITATION STARTS UP AGAIN MONDAY MORNING.
&&
.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
MODELS SHOWING THE COLD FRONT MOVING OFF THE COAST MONDAY NIGHT.
AN AREA OF SLEET/FREEZING RAIN AND SNOW WILL END FROM NORTHWEST TO
SOUTHEAST MONDAY EVENING AS THE FRONT PUSHES SOUTH. HIGH PRESSURE
BUILDS IN FOR TUESDAY AND CHRISTMAS DAY. SHOULD BE A FEW SCATTERED
SNOW SHOWERS IN THE MOUNTAINS TUESDAY AS THE UPPER LOW MOVES
THROUGH. WEDNESDAY SHOULD BE THE COLDEST DAY OF THE WEEK BUT THIS
COLD AIR LIFTS OUT QUICKLY. A COLD FRONT SHOULD MOVE THROUGH
THURSDAY OR FRIDAY. THE ECMWF AND GFS ARE ABOUT 12 HOURS OFF ON
THE TIMING OF THIS FRONT WITH THE ECMWF BEING SLOWER.
&&
.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
SHORT TERM...FREEZING RAIN CONTINUES THROUGH TODAY WITH IFR
CONDITIONS. MOST LIKELY AREAS TO SEE FREEZING RAIN ARE THE MAINE
TERMINALS. PORTSMOUTH... CONCORD... WHITEFIELD... AND LEBANON MAY
NOT SEE FREEZING RAIN.
LONG TERM...EXPECT MVFR FOR PWM AND PSM MONDAY NIGHT BEFORE THE
FRONT SLIDES OFF THE COAST. VFR TUESDAY THROUGH THE END OF THE
WEEK.
&&
.MARINE...
SHORT TERM...NORTHEAST WINDS WILL PICK UP THIS MORNING TO THE
NORTH OF THE OFFSHORE FRONT. COULD SEE SOME GUSTS TO 25 KT... SO
THE SMALL CRAFT ADVISORY HAS BEEN CONVERTED TO A GENERIC ADVISORY
TO COVER BOTH WINDS AND SEAS.
LONG TERM...SMALL CRAFT ADVISORIES MAY BE NEEDED TUESDAY NIGHT AND
WEDNESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...ICE STORM WARNING UNTIL NOON EST MONDAY FOR MEZ012>014-019>022-
024>028.
FREEZING RAIN ADVISORY UNTIL 6 AM EST MONDAY FOR MEZ018-023.
WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR MEZ007>009.
NH...ICE STORM WARNING UNTIL 6 AM EST MONDAY FOR NHZ002-004.
FREEZING RAIN ADVISORY UNTIL 6 AM EST MONDAY FOR NHZ003-005-
006-008>010-013.
WINTER STORM WARNING UNTIL 7 AM EST MONDAY FOR NHZ001.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR ANZ150-152-154.
&&
$$
SHORT TERM...KIMBLE
LONG TERM...HAWLEY
AREA FORECAST DISCUSSION
NWS ELKO NV
329 AM PST SUN DEC 22 2013
.SYNOPSIS...LINGERING PACIFIC MOISTURE WILL IMPACT PORTIONS OF
ELKO COUNTY TODAY POTENTIALLY RESULTING IN FLURRIES. BIG PICTURE
WISE...WIDESPREAD NORTHERLY FLOW WILL BE REPLACED BY RIDGING.
EXPECTING INVERSIONS TO DEVELOP OVER THE VALLEYS WHICH WILL BRING
THE SINGLE DIGIT TEMPERATURES BACK. OTHER THAN THE COLD SNAP OVER
NORTHERN NEVADA...GENERALLY EXPECTING MILD CONDITIONS FOR
CHRISTMAS AND THROUGH FRIDAY.
&&
.SHORT TERM...TODAY THROUGH TUESDAY. THE PROGGED SOUNDING FOR ELKO
CONTINUES TO DEPICT SATURATION OR NEAR SATURATION...WHICH IS
CONSISTENT WITH THE RECENT SNOW MELT AND MOISTURE ADVECTION FROM
THE PACIFIC SYSTEM. THE GFS PINGS INTO NEAR 90 PERCENT RH FROM 700 MB
TO 500 MB OVER THE NORTHERN ZONES OF LKN THROUGH 18Z TODAY.
MEANWHILE...THE NAM AND RUC TAKE IT ONE STEP FURTHER BRINGING SNOW
INTO THE NORTHERN HALF OF ELKO COUNTY. FLURRIES WILL BE POSSIBLE
IN THE JARBIDGE WILDERNESS AREA AND JACKPOT...BUT MOST OF THE
REGION WILL BE UNEVENTFUL. IN THE WAKE OF THE EXTENSIVE MELTING
THAT OCCURRED SATURDAY AFTERNOON...THERE HAS BEEN MUCH DISCOURSE OVER THE
POTENTIAL FOR THE DEVELOPMENT OF FREEZING FOG THIS MORNING. KEPT
PATCHY FREEZING FOG IN THE GRIDS.
.LONG TERM...CHRISTMAS EVE THROUGH NEXT SATURDAY. QUIET WEATHER
CAN BE EXPECTED ACROSS THE WESTERN GREAT BASIN THROUGH CHRISTMAS
WEEK. THE HOLIDAY WEEK BEGINS WITH A WEAK NORTHWEST FLOW IN PLACE
ACROSS THE GREAT BASIN. AS THE WEEK CONTINUES A WEAK TROUGH SLIDES
SOUTHEAST WITHIN THE NORTHWEST FLOW ALOFT ACROSS THE GREAT BASIN
ON CHRISTMAS DAY. SINCE THIS TROUGH IS MOISTURE STAVED AND
POSITIVELY TILTED...NOTHING MORE THAN A FEW CLOUDS CAN BE EXPECTED
MAINLY OVER NORTHERN AREAS.
FOLLOWING THIS TROUGH...A STRONG RIDGE OVER THE EASTERN PACIFIC WILL
BUILD INTO THE WESTERN STATES CONTINUING DRY AND COLD CONDITIONS.
MODEL SOUNDINGS BENEATH THIS RIDGE INDICATE A STRONG INVERSION WILL
BE IN PLACE MAINLY ESPECIALLY OVER NORTHERN AREAS. STRONG
RADIATIONAL COOLING ESPECIALLY IN SNOW COVER AREAS WILL DROP
TEMPERATURES INTO THE SINGLE DIGITS AT NIGHT. RECOVERY DURING THE
DAY WILL BE LIMITED WITH THE STRONG INVERSION IN PLACE...SO EXPECT
MAXIMUM TEMPERATURES TO REBOUND INTO THE UPPER 20S/LOWER 30S IN MANY
VALLEY AREAS. THE HIGHER ELEVATIONS ABOVE THE INVERSION WITH SEE
TEMPERATURES IN THE 30S AND 40S. THE RIDGE GRADUALLY WILL BREAKDOWN
DURING FRIDAY ALLOWING A TROUGH TO APPROACH FROM THE NORTHWEST WITH
SOME MOISTURE FOR MAINLY NORTHERN AREAS ON SATURDAY.
&&
.AVIATION...WITH ABUNDANT LOW LEVEL MOISTURE IN PLACE FROM RAPID
SNOWMELT SATURDAY...FOG AND LOW CIGS BECOMES THE CONCERN FOR MAINLY
THE NORTHERN AND EASTERN TAF LOCATIONS. WITH THE NEW AVIATION
PACKAGE PLAN TO MENTION VCFG AT KWMC/KEKO/KELY THIS MORNING AND A
COMBINATION OF MVFR/VFR CIGS THROUGH THE DAY. KTPH SHOULD BE IN
BETTER SHAPE WITH SKC CONDITIONS.
&&
.LKN WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
97/89/89
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
702 AM EST SUN DEC 22 2013
.SYNOPSIS...
LOW PRESSURE OVER NORTHERN OHIO WILL CONTINUE NORTHEAST TODAY
GIVING A KICK TO A FRONT STALLED ACROSS THE AREA. THE FRONT WILL
MOVE EAST OF THE AREA BY THE AFTERNOON ALLOWING DRIER BUT NOTABLY
COLDER AIR TO MOVE INTO THE AREA FOR MUCH OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...NO SIGNIFICANT CHANGES FOR THE UPDATE.
ORIGINAL...MODERATE TO LOCALLY HEAVY RAIN STILL OCCURRING ACROSS
THE CENTRAL AND EASTERN COUNTIES EARLY TODAY HOWEVER MODELS SHOW
DRIER AIR WRAPPING AROUND THE SYSTEM WILL MOVE IN FROM THE
SOUTHWEST TODAY. FOLLOWED SREF POP GUIDANCE STARTING WITH
CATEGORICAL POPS EARLY...DROPPING TO SLIGHT CHANCE WEST OF A KCLE
TO KMFD LINE BY 15Z. BY 18Z WILL DROP FAR EASTERN COUNTIES TO
CHANCE AND MUCH OF THE REST OF THE AREA TO SLIGHT CHANCE OR LOWER.
HIGHS WILL BE VERY TRICKY TODAY AND HAVE USED THE HRRR WHICH IS
ABLE TO BEST GRAPHICALLY HANDLE MOVING THE TIGHT GRADIENT ACROSS
THE AREA. IN SHORT...EXPECT TEMPS IN THE EAST AND CENTRAL COUNTIES
TO RECOVER WITH THE MILD AIR LIFTING TO THE LAKESHORE AGAIN EARLY
WHILE THE WEST WILL REMAIN COOL. DURING THE AFTERNOON THE COOLER
AIR WILL SWEEP SOUTHEAST. WILL CONTINUE WITH THE FLOOD WATCH AS
IS.
MEDIA REMIND YOUR VIEWERS AND LISTENERS NOT TO DRIVE THROUGH
FLOODED AREAS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
SHOULD GET A BIT OF A BREAK TONIGHT AS THE DRY SLOT CONTINUE
THROUGH THE AREA ALTHOUGH BY MORNING MONDAY 850MB TEMPS WILL BE
DOWN TO -7 TO -9 ON THE LAKE. WHILE THIS WILL NOT BE ENOUGH FOR
LAKE EFFECT TEMPS CONTINUE TO FALL TO -12C OR SO THROUGH THE
AFTERNOON SO WOULD EXPECT CHANCES FOR SNOW WILL INCREASE AS THE DAY
WEARS ON. WILL HAVE CHANCE POPS ACROSS THE SNOW BELT IN THE
MORNING INCREASING TO LIKELY IN THE AFTERNOON. TEMPS CONTINUE TO
DROP TO -14C BY 12Z TUESDAY WHILE THE CORE OF THE COLD AIR
(-20C) THANKFULLY DROPS ACROSS SOUTHERN AND CENTRAL OHIO. STILL
HOWEVER...-14C WILL BE LOW ENOUGH FOR LAKE EFFECT TO CONTINUE AND
IN FACT WILL HAVE CATEGORICAL POPS FOR THE OVERNIGHT MONDAY
NIGHT...DROPPING BACK TO LIKELY TUESDAY. TUESDAY NIGHT HIGH
PRESSURE AND DRIER AIR WILL MOVE QUICKLY ACROSS THE AREA
COUNTERING THE -16C TEMPS ON THE LAKE. WILL DROP POPS THROUGH
LIKELY TO CHANCE THROUGH THE NIGHT. WEDNESDAY A WARM FRONT WILL
MOVE THROUGH THE WESTERN LAKE WITH OVERRUNNING MOISTURE BRUSHING
THE AREA. AM CONCERNED THAT A LIGHT SNOW DEVELOPS SO WILL HAVE LOW
CHANCE POPS IN PLACE FOR THE DAY. WEDNESDAY NIGHT HEIGHTS DROP AS
AN UPPER LOW/TROF MOVES BACK INTO THE GREAT LAKES REGION SO WILL
CONTINUE WITH LOW CHANCE POPS.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
THURSDAY COLD FRONT MOVES THROUGH THE AREA HOWEVER THERE ARE
DIFFERENCES BETWEEN THE GFS AND ECMWF TIMING WITH THE ECMWF SLOWER
OF THE TWO. WILL FOLLOW WPC/ECMWF GUIDANCE THROUGH THE LONG TERM
PERIOD GENERALLY BRINGING BACK A SHOT AT LAKE EFFECT SNOW THURSDAY
THROUGH FRIDAY...DRYING IT OUT FOR SATURDAY AS HIGH PRESSURE
BUILDS IN.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
LOW PRESSURE NEAR TIFFIN OHIO IS MOVING QUICKLY TOWARD LAKE ERIE
WITH ITS WARM FRONT SWEEPING QUICKLY TO THE NORTH INTO LAKE ERIE.
GUSTY SOUTHERLY WINDS OF 25 TO 35 KNOTS PREVAIL EAST OF THE LOW.
LOW CLOUDS HAVE CLEARED OUT OF THE WARM SECTOR AND HAVE LEFT ONLY
MID CLOUDS WITH VFR CONDITIONS BUT STILL SOME LIGHT RAIN MAINLY
EAST OF I-71. OVER WESTERN OHIO BEHIND THE COLD FRONT...
SOUTHWESTERLY WINDS ARE ADVECTING LOW CLOUDS EAST WHICH WILL
OVERSPREAD THE REGION TODAY. EXPECT MVFR TO IFR CIGS TO OVERSPREAD
THE REGION. ONCE COOLER AIR SPREADS INTO THE REGION FROM THE WEST
TOWARD NOON...WIND GUSTS SHOULD SUBSIDE TO 20 TO 25 KNOTS AND
FURTHER WEAKEN AFTER 21Z. TOWARD SUNSET EXPECT IFR CIGS TO DEVELOP
AND PERSIST OVERNIGHT AS COLDER AIR MOVES INTO THE REGION. SOME
LIGHT SNOW WILL MOVE INTO THE AREA AND MAINLY AFFECT THE MFD CAK
CLE YNG AND ERI TAF SITES IN NORTH CENTRAL AND NORTHEAST OHIO AND
NW PA.
.OUTLOOK...SPOTTY NON VFR LINGERS INTO MONDAY...IMPROVING BY
TUESDAY NIGHT. BY WEDNESDAY MOSTLY VFR CONDITIONS.
&&
.MARINE...
UPDATED...WINDS IN THE WARM SECTOR GUSTING AROUND 30 KNOTS WHILE
WINDS IN THE COOLER AIR ARE NOT AS STRONG. WHILE THE STRONGER
WINDS WILL NOT REACH TOO FAR ONTO THE LAKE GIVEN THAT THE WATER IS
MUCH COOLER THAN THE AIR...FELT STILL THAT A SMALL CRAFT WOULD BE
WARRANTED AS WINDS CLOSE TO SHORE WOULD BE STRONG.
PREVIOUS...EXPECTING A VARIABLE WIND EARLY TODAY AS LOW PRESSURE
TRACKS ACROSS THE REGION. WINDS WILL TURN SOUTHWEST 15 TO 25 KNOTS
BEHIND THE LOW HOWEVER FOR MUCH OF TODAY. HIGH PRESSURE WILL BUILD
IN FOR LATE MONDAY AND TUESDAY TURNING WINDS NORTHWEST AT 10 TO 20
KNOTS OR SO. MID WEEK THE HIGH MOVES EAST AND WINDS TURN SOUTH TO
SOUTHWEST AT 15 TO 25 KNOTS REACHING NEAR 30 KNOTS THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR OHZ003-006>014-
017>023-027>033-036>038-047-089.
PA...FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR PAZ001>003.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
LEZ145>149.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...TK
AVIATION...LAPLANTE
MARINE...TK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
637 AM EST SUN DEC 22 2013
.SYNOPSIS...
LOW PRESSURE OVER NORTHERN OHIO WILL CONTINUE NORTHEAST TODAY
GIVING A KICK TO A FRONT STALLED ACROSS THE AREA. THE FRONT WILL
MOVE EAST OF THE AREA BY THE AFTERNOON ALLOWING DRIER BUT NOTABLY
COLDER AIR TO MOVE INTO THE AREA FOR MUCH OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...NO SIGNIFICANT CHANGES FOR THE UPDATE.
ORIGINAL...MODERATE TO LOCALLY HEAVY RAIN STILL OCCURRING ACROSS
THE CENTRAL AND EASTERN COUNTIES EARLY TODAY HOWEVER MODELS SHOW
DRIER AIR WRAPPING AROUND THE SYSTEM WILL MOVE IN FROM THE
SOUTHWEST TODAY. FOLLOWED SREF POP GUIDANCE STARTING WITH
CATEGORICAL POPS EARLY...DROPPING TO SLIGHT CHANCE WEST OF A KCLE
TO KMFD LINE BY 15Z. BY 18Z WILL DROP FAR EASTERN COUNTIES TO
CHANCE AND MUCH OF THE REST OF THE AREA TO SLIGHT CHANCE OR LOWER.
HIGHS WILL BE VERY TRICKY TODAY AND HAVE USED THE HRRR WHICH IS
ABLE TO BEST GRAPHICALLY HANDLE MOVING THE TIGHT GRADIENT ACROSS
THE AREA. IN SHORT...EXPECT TEMPS IN THE EAST AND CENTRAL COUNTIES
TO RECOVER WITH THE MILD AIR LIFTING TO THE LAKESHORE AGAIN EARLY
WHILE THE WEST WILL REMAIN COOL. DURING THE AFTERNOON THE COOLER
AIR WILL SWEEP SOUTHEAST. WILL CONTINUE WITH THE FLOOD WATCH AS
IS.
MEDIA REMIND YOUR VIEWERS AND LISTENERS NOT TO DRIVE THROUGH
FLOODED AREAS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/...
SHOULD GET A BIT OF A BREAK TONIGHT AS THE DRY SLOT CONTINUE
THROUGH THE AREA ALTHOUGH BY MORNING MONDAY 850MB TEMPS WILL BE
DOWN TO -7 TO -9 ON THE LAKE. WHILE THIS WILL NOT BE ENOUGH FOR
LAKE EFFECT TEMPS CONTINUE TO FALL TO -12C OR SO THROUGH THE
AFTERNOON SO WOULD EXPECT CHANCES FOR SNOW WILL INCREASE AS THE DAY
WEARS ON. WILL HAVE CHANCE POPS ACROSS THE SNOW BELT IN THE
MORNING INCREASING TO LIKELY IN THE AFTERNOON. TEMPS CONTINUE TO
DROP TO -14C BY 12Z TUESDAY WHILE THE CORE OF THE COLD AIR
(-20C) THANKFULLY DROPS ACROSS SOUTHERN AND CENTRAL OHIO. STILL
HOWEVER...-14C WILL BE LOW ENOUGH FOR LAKE EFFECT TO CONTINUE AND
IN FACT WILL HAVE CATEGORICAL POPS FOR THE OVERNIGHT MONDAY
NIGHT...DROPPING BACK TO LIKELY TUESDAY. TUESDAY NIGHT HIGH
PRESSURE AND DRIER AIR WILL MOVE QUICKLY ACROSS THE AREA
COUNTERING THE -16C TEMPS ON THE LAKE. WILL DROP POPS THROUGH
LIKELY TO CHANCE THROUGH THE NIGHT. WEDNESDAY A WARM FRONT WILL
MOVE THROUGH THE WESTERN LAKE WITH OVERRUNNING MOISTURE BRUSHING
THE AREA. AM CONCERNED THAT A LIGHT SNOW DEVELOPS SO WILL HAVE LOW
CHANCE POPS IN PLACE FOR THE DAY. WEDNESDAY NIGHT HEIGHTS DROP AS
AN UPPER LOW/TROF MOVES BACK INTO THE GREAT LAKES REGION SO WILL
CONTINUE WITH LOW CHANCE POPS.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
THURSDAY COLD FRONT MOVES THROUGH THE AREA HOWEVER THERE ARE
DIFFERENCES BETWEEN THE GFS AND ECMWF TIMING WITH THE ECMWF SLOWER
OF THE TWO. WILL FOLLOW WPC/ECMWF GUIDANCE THROUGH THE LONG TERM
PERIOD GENERALLY BRINGING BACK A SHOT AT LAKE EFFECT SNOW THURSDAY
THROUGH FRIDAY...DRYING IT OUT FOR SATURDAY AS HIGH PRESSURE
BUILDS IN.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
LOW PRESSURE IS NOW IN SOUTHWEST OHIO WITH A WARM FRONT EXTENDING
NORTHEAST THROUGH MANSFIELD TO MEADVILLE. THE LOW WILL CONTINUE TO
MOVE NORTHEAST ALONG THE FRONT AND KEEP THE RAIN GOING THROUGH
MUCH OF THE NIGHT. A LINE OF SHOWERS AND MINIMAL THUNDERSTORMS
WILL MOVE THROUGH MANSFIELD AND AKRON CANTON AREA AND WILL PRODUCE
GUSTY WINDS AS IT MOVES THROUGH THE AREA.
WE WILL CONTINUE TO SEE SOME VERY LOW CEILINGS THROUGH THE NIGHT
DUE TO THE PROXIMITY OF THE FRONTAL BOUNDARY AND LOW PRESSURE
SYSTEM. POCKETS OF HEAVY RAIN COULD DROP VISIBILITIES
CONSIDERABLY FOR BRIEF PERIODS.
EXPECTING RAIN TO FINALLY END FROM WEST TO EAST BEGINNING AROUND
12Z AS RAIN PULLS OUT OF THE REGION.
WINDS WILL BE VARIABLE THROUGH THE FORECAST PERIOD DUE TO THE LOW
PRESSURE SYSTEM TRACKING ACROSS THE AREA.
.OUTLOOK...SPOTTY NON VFR LINGERS INTO MONDAY...IMPROVING BY
TUESDAY NIGHT. BY WEDNESDAY MOSTLY VFR CONDITIONS.
&&
.MARINE...
UPDATED...WINDS IN THE WARM SECTOR GUSTING AROUND 30 KNOTS WHILE
WINDS IN THE COOLER AIR ARE NOT AS STRONG. WHILE THE STRONGER
WINDS WILL NOT REACH TOO FAR ONTO THE LAKE GIVEN THAT THE WATER IS
MUCH COOLER THAN THE AIR...FELT STILL THAT A SMALL CRAFT WOULD BE
WARRANTED AS WINDS CLOSE TO SHORE WOULD BE STRONG.
PREVIOUS...EXPECTING A VARIABLE WIND EARLY TODAY AS LOW PRESSURE
TRACKS ACROSS THE REGION. WINDS WILL TURN SOUTHWEST 15 TO 25 KNOTS
BEHIND THE LOW HOWEVER FOR MUCH OF TODAY. HIGH PRESSURE WILL BUILD
IN FOR LATE MONDAY AND TUESDAY TURNING WINDS NORTHWEST AT 10 TO 20
KNOTS OR SO. MID WEEK THE HIGH MOVES EAST AND WINDS TURN SOUTH TO
SOUTHWEST AT 15 TO 25 KNOTS REACHING NEAR 30 KNOTS THURSDAY.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR OHZ003-006>014-
017>023-027>033-036>038-047-089.
PA...FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR PAZ001>003.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
LEZ145>149.
&&
$$
SYNOPSIS...TK
NEAR TERM...TK
SHORT TERM...TK
LONG TERM...TK
AVIATION...LOMBARDY
MARINE...TK
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
536 AM CST SUN DEC 22 2013
.AVIATION...
VFR IS EXPECTED THROUGH THE TAF PERIOD. THERE EXISTS A VERY SMALL
CHANCE AT SNOW FLURRIES AT KLBB DURING THE MORNING HOURS BUT
CHANCES ARE TOO LOW TO MENTION IN THE TAF.
&&
.PREV DISCUSSION... /ISSUED 331 AM CST SUN DEC 22 2013/
SHORT TERM...
WINTER DOES NOT WANT TO LET UP FOR THE REGION WITH RENEWED CHANCES
FOR LIGHT PRECIPITATION THIS MORNING. ANOTHER TROUGH AXIS HAS STILL
TO PASS LATER THIS MORNING. WEAK Q-VECTOR CONVERGENCE IS CURRENTLY
MOVING OVER THE AREA. THIS WAS COUPLED WITH WEAK FRONTOGENETICAL
FORCING AROUND 750-700MB EDGING INTO THE SOUTHWESTERN TEXAS
PANHANDLE. MODELS WERE IN GOOD AGREEMENT SHOWING LIFT PEAKING AROUND
12Z UNDER SATURATED SOUNDINGS. ALTHOUGH...THE ONLY DIFFERENCE
BETWEEN MODEL RAP AND NAM SOUNDINGS IS A DRY NEAR SURFACE LAYER
DEPICTED BY THE NAM. THIS CAN CERTAINLY MAKE A DIFFERENCE IN SNOW
TOTALS WITH THE MORE MOIST RAP SHOWING MORE SNOWFALL.
LONG TERM...
WITH THE EXIT EAST OF THE CURRENT LONG-WAVE TROUGH MONDAY...LESSER
AMPLITUDE AND DRY NORTHWEST FLOW WILL BECOME DOMINANT THROUGH MUCH
OF THE WEEK. NEXT SHORT-WAVE UPPER TROUGH WILL SKIM BY TO THE
NORTH WEDNESDAY DRAGGING A SLIGHTLY WEAKER FRONT INTO THE AREA
EARLY WEDNESDAY THAN PREVIOUSLY ADVERTISED. FLATTER WESTERLY FLOW
APPEARS IN THE WORKS EARLY NEXT WEEKEND WITH BACKING AND INCREASING
SOUTHWEST FLOW ALOFT LATER IN THE WEEKEND...ALTHOUGH SPREAD IN THE
DEVELOPING INTER-MOUNTAIN UPPER TROUGH WILL BE ON THE RISE. THIS
PATTERN WILL YIELD MODEST WARMING MONDAY...A WEAK BACK-DOOR FRONT
WILL SLIP IN MONDAY AFTERNOON AND EVENING...WITH BETTER WARMING
AND GUSTY SOUTHWEST WINDS TUESDAY. THEN THE SLIGHT CHRISTMAS DAY
COOL-DOWN WITH SLOW WARMING THURSDAY AND FRIDAY. BIGGER BOOST IN
TEMPERATURES AND MORE GUSTY SOUTHWEST BREEZES EXPECTED SATURDAY
BEFORE NEXT COOLING THE FOLLOWING SUNDAY. MINOR CHANGES. RMCQUEEN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 37 19 46 24 55 / 10 0 0 0 0
TULIA 38 20 46 24 56 / 10 0 0 0 0
PLAINVIEW 40 21 49 25 56 / 10 0 0 0 0
LEVELLAND 42 23 51 26 56 / 10 0 0 0 0
LUBBOCK 42 23 52 26 57 / 0 0 0 0 0
DENVER CITY 44 23 52 28 55 / 10 0 0 0 0
BROWNFIELD 44 23 52 27 56 / 0 0 0 0 0
CHILDRESS 40 22 49 24 57 / 0 0 0 0 0
SPUR 45 22 53 27 57 / 0 0 0 0 0
ASPERMONT 45 23 53 29 58 / 0 0 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
01
AREA FORECAST DISCUSSION
NWS ALBANY NY
1257 PM EST SUN DEC 22 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT FROM CENTRAL NEW YORK TO THE MAINE COAST
WILL SHIFT SLIGHTLY AS A STORM MOVES ALONG IT TODAY. NORTH OF IT
IT WILL BE CHILLY WITH RAIN AND FREEZING RAIN...WITH RAIN AND VERY
MILD WEATHER TO ITS SOUTH. THE STORM WILL DRAG A COLD FRONT
THROUGH THE REGION TONIGHT AND THEN SLIDE SLOWLY OFFSHORE MONDAY.
HIGH PRESSURE WILL BUILD FROM ONTARIO INTO NEW YORK TUESDAY INTO
CHRISTMAS...WITH MUCH COLDER AIR FILTERING INTO THE REGION. THE
WEEK WILL END WITH A SERIES OF FAST MOVING WEATHER SYSTEMS WITH
BOUTS OF SNOW SHOWERS AND GENERALLY SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1100 AM...HIGHLY VARIABLE CONDITIONS PERSIST ACROSS THE
FORECAST AREA. TEMPS ARE IN THE UPPER 20S TO LOWER 30S FROM THE LAKE
GEORGE SARATOGA REGION INTO THE CAPITAL DISTRICT...IN THE UPPER 30S
TO LOWER 40S IN THE MOHAWK VALLEY...THE ADIRONDACKS AND THE VALLEYS
OF SOUTHERN VERMONT...AND IN THE 50S TO MID 60S ELSEWHERE.
EVENTUALLY EXPECT THE WARM AIR TO ARRIVE IN ALL LOCATIONS...BUT FOR
NOW HAVE ADJUSTED THE HOURLY TEMPS/DEWPOINTS TO REFLECT CURRENT
CONDITIONS...AND ALSO LOWERED MAX TEMPS BY AROUND 10 DEGREES IN
THOSE AREAS WERE THE LOW-LEVEL COLD AIR STILL PERSISTS.
WITH TEMPS NOT MOVING MUCH WHERE THE LOW-LEVEL COLD AIR STILL
LINGERS...HAVE EXTENED THE FREEZING RAIN ADVISORY IN THE LAKE GEORGE
SARATOGA REGION THROUGH 200 PM. PCPN HAS BECOME INTERMITENT AND
LIGHT SO ADDITIONAL ICE ACCUMULATIONS WILL GENERALLY BE UNDER A
TENTH OF AN INCH.
WITH THE NEXT UPDATE WILL CONSIDER DROPPING THE FLOOD WATCH SINCE IT
APPEARS LIKELY THAT ADDITIONAL RAINFALL TODAY WILL BE FAIRLY LIGHT.
.PREVIOUS DISCUSSION...
AS OF 635 AM EST...WIDE VARIETY OF TEMPERATURES ACROSS THE REGION
THIS MORNING WITH STALLED FRONTAL BOUNDARY SITUATED DIRECTLY
ACROSS THE CENTRAL PORTION OF THE CWA. NORTH OF THE
BOUNDARY...VERY COLD CANADIAN AIR IS BEING PULLED SOUTHWARD THANKS
TO A LOW LEVEL NNE FLOW THROUGH THE CHAMPLAIN VALLEY AND INTO THE
HUDSON VALLEY REGION. THIS HAS ALLOWED TEMPS TO DROP BELOW
FREEZING FOR THE GLENS FALLS AND SARATOGA SPRINGS AREA. TEMPS HAVE
FALLEN INTO THE LOW TO MID 30S IN THE CAPITAL REGION.
AT THE SAME TIME...VERY WARM TEMPS ALOFT ARE IN PLACE THANKS TO A
STRONG SOUTHERLY FLOW. AS A RESULT...SOME OF THE WARMER TEMPS AT THIS
HOUR ARE ACROSS THE MOUNTAIN PEAKS OF THE CATSKILLS...SRN GREENS
AND BERKSHIRES...WHERE TEMPS ARE WELL INTO THE 50S. ALSO...A
SOUTHERLY LOW LEVEL WIND COMING UP THE MID HUDSON VALLEY HAS
ALLOWED SOME WARMER AIR TO MOVE TOWARDS POUGHKEEPSIE AND
HUDSON...WITH SFC TEMPS HAVING JUMPED UP INTO THE LOW 60S! THE
JUST LAUNCHED 12Z KALY SOUNDING SHOWS THE COLD SFC LAYER IS ONLY
ABOUT 200 METERS THICK...WITH A WARM NOSE OF ABOUT +16 C AT 850 HPA.
WITH AN APPROACHING LOW PRESSURE AREA AND THE SFC BOUNDARY IN
PLACE...OVERRUNNING PRECIP HAS MOVED TO THE NORTH OF THE
REGION...FALLING AS FZRA/PL ACROSS THE BTV CWA. RIGHT NOW...MUCH
OF OUR CWA IS IN A DRY SLOT...WITH JUST SOME SPOTTY FREEZING RAIN
ACROSS THE SOUTHEASTERN ADIRONDACKS...AND SOME LIGHT RAIN SHOWERS
ACROSS WESTERN NEW ENGLAND. THE LATEST 08Z 3KM HRRR SHOWS THIS DRY
SLOT SHOULD START TO FILL IN TOWARDS THE MID MORNING AS THE LOW
PRESSURE AREA MOVES NORTHEAST ACROSS THE OHIO VALLEY AND
EVENTUALLY TOWARDS UPSTATE NY. RIGHT NOW...WE WILL HOLD CHC POPS
FOR THE NEXT FEW HOURS ACROSS CENTRAL/SOUTHERN PARTS OF THE
AREA...WITH LIKELY/CATEGORICAL POPS ACROSS THE FAR NORTH NEAR THE
BTV CWA BORDER. BY THE LATE MORNING...WE WILL RISE POPS TO
LIKELY/CATEGORICAL FOR WESTERN AND CENTRAL PARTS OF THE CWA AS
WELL.
FOR NOW...IT DOESN/T APPEAR THAT THE CAPITAL REGION WILL BE SEEING
ANY MEASUREABLE FREEZING RAIN...AS THE APPROACHING STORM SHOULD
ALLOW THE STALLED BOUNDARY TO START TO MOVE NORTHWARD AS A WARM
FRONT...AND BRING THE ALBANY AREA INTO THE WARM SECTOR ONCE THE
NEXT ROUND OF RAINFALL BEGINS. ALTHOUGH THERE MAY BE A SPOTTY
SPRINKLE BEFORE THAT OCCURS...IT SHOULDN/T BE ABLE TO ACCRETE MUCH
ICE AT ALL WITH MARGINAL TEMPS AND AN ALREADY WET GROUND.
STILL...WE HAVE PASSED ALONG THE MESSAGE THROUGH OUR SOCIAL MEDIA
CHANNELS THAT WITH TEMPS NEAR FREEZING...SOME WET SURFACES COULD
POTENTIALLY BE SLICK...ALTHOUGH THIS WILL LIKELY BE RATHER SPOTTY.
BASED ON WHATS HAPPENING AT KPOU/1B1...THIS WARMER AIR IS ON THE
MOVE...AND SHOULD WIN OUT OVER THE COLD AIR IN THE CAPITAL REGION
AS THE STRONG STORM SYSTEM MOVES TOWARDS OUR AREA FAIRLY SOON.
HOWEVER...FURTHER NORTH ACROSS THE LAKE GEORGE AREA...IT MAY TAKE
UNTIL THE MID TO LATE MORNING FOR THE WARM FRONT TO MOVE THROUGH
AND TEMPS TO WARM UP. AS A RESULT...A PROLONGED PERIOD OF FREEZING
RAIN CAN BE EXPECTED ACROSS THE LAKE GEORGE SARATOGA REGION. ICE
ACCRETION AMOUNTS WILL RANGE FROM A TRACE TO A TENTH ACROSS THE
SARATOGA SPRINGS AREA TO A FEW TENTHS FOR GLENS FALLS TO ABOUT
FOUR TENTHS ACROSS THE NORTH END OF LAKE GEORGE. ASIDE FROM SOME
HAZARDOUS DRIVING CONDITIONS...THIS MAY LEAD TO SOME ISOLATED
POWER OUTAGES.
AREAS IN THE WARM SECTOR SHOULD SEE SFC TEMPS WARM
SIGNIFICANTLY...AS THOSE WARMER TEMPS ALOFT ARE MIXED IN THE
BOUNDARY LAYER. MAX TEMPS LOOK TO REACH INTO THE 50S ACROSS MUCH OF
THE CENTRAL AND SOUTHERN PARTS OF THE AREA...WITH SOME MID 60S FOR
THE MID HUDSON VALLEY.
WHILE IT WILL RAIN DURING THE MID TO LATE MORNING HOURS...MOST AREAS
WILL BE DONE SEEING PRECIPITATION BY THE EARLY TO MID AFTN
HOURS...AS THE STORM/S COLD FRONT PASSES THROUGH THE AREA. TOTAL
RAINFALL FOR SUNDAY WILL RANGE FROM JUST A QUARTER OF AN INCH
ACROSS LITCHFIELD COUNTY CT...TO AROUND THREE QUARTERS OF AN INCH
IN THE CAPITAL REGION TO ABOUT AN INCH AND A HALF OVER THE
ADIRONDACKS. SEE THE HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL
TO AFFECT AREA RIVERS AND STREAMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
FOR THIS PERIOD THE MODEL SUITE (GEM/GFS/ECMWF) ARE IN FAIRLY
GOOD AGREEMENT. DURING THE THIS EVENING THE SFC LOW AND ITS UPPER
DYNAMICS WILL LIFT NE OUT OF FCA. A SERIES OF 500HPA SHORT WAVES
WILL DIG A TROF OVER GRTLKS...MAINTAINING A STRONG SW 500HPA FLOW
OVER THE EASTERN THIRD OF THE NATION. FOR A TIME THIS WILL ACT TO
WEAKEN THE SFC LOW FURTHER OVER NEW ENG...BUT THE SFC LOW WILL
DRAG A CDFNT THROUGH THE REGION TNGT. GIVEN THE UPPER FLOW COOLER
AIR WILL BE SLOW TO FILTER IN OVERNIGHT....AND TEMPS WILL REMAIN
ABV FREEZING IN MOST AREAS...WITH SNOW MELT CONTINUING.
BY MONDAY THIS CDFNT WILL NEARLY STALL ALONG THE EASTERN
SEABOARD...AND WITH DIGGING 500HPA TROF INTERACTING WITH THE COASTAL
BAROCLINIC ZONE WILL TRIGGER A BOUT OF OVERRUNINNG RAIN...ALONG THE
I-95 CORRIDOR THAT WILL BACK BUILD INTO SE PORTIONS OF FCA. QPF
DURING MONDAY WITH THIS SHOULD BE 0.25 TO 0.50 IN THESE AREAS...AND
GIVEN THESE AREAS WERE IN THE WARM SECTOR MUCH OF THE CURRENT
EVENT...THEY MELTED MOST OF THEIR SNOW...BUT HAD LITTLE RAINFALL.
ADD TO THAT THE 2-3 DAYS THIS OCCURRED...THE ADDITIONAL RAIN IN
SOUTHEAST AREAS MONDAY SHOULD NOT RESULT IN ANYTHING OTHER THAN
WITHIN BANK RISES.
FURTHER WEST MONDAY AS HIGH PRESSURE BUILDS EAST WIND GRADIENT
WILL INCR AND AS THE 500HPA TROF PUSHES EAST A MUCH STRONGER 2NDRY
CDFNT WILL PUSH INTO THE REGION LATE MONDAY AND THROUGH MONDAY
NIGHT. TEMPS MONDAY WILL HOLDS STEADY THEN FALL DURING THE AFTN.
MONDAY NIGHT INTO TUES THE PASSAGE OF THE 500HPA TROF...CAA WILL
RESULT IN SCT -SHSN ACTIVITY. HWVR LLVL FLOW WILL BE TOTALLY
UNFAVORABLE FOR LK EFFECT OVER EASTERN NY.
ONCE THE 500HPA TROF EXITS CHRISTMAS EVE BOTH A 500HPA RIDGE...AND
SFC HIGH PRESSURE WILL SETTLE OVER NYS AND MID ATLC REGION. THIS
WILL SET THE STAGE FOR A FRIGID NIGHT WITH IDEAL RADIATIONAL
COOLING...ONE OF THE LONGEST NIGHTS OF THE YEAR...CLEAR SKIES AND
DRY AIR MASS. LOWS WILL PLUNGE TO -20F IN PARTS OF THE ADIRONDACKS
TO AROUND 10 IN THE SE.
TEMPS WILL RECOVER CHRISTMAS DAY TO THE TEENS AND 20S AS SFC HIGH
SLIDES OFFSHORE. SOME CLOUDS MAY ARRIVE IN THE AFTERNOON AS NEXT
WEAK SYSTEM APPROACHES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
THE EFP WILL FEATURE A SERIES OF FAST MOVING SYSTEMS IN W-NW FLOW.
MOST WILL BE FAIRLY WK CDFNTS AND/OR 500HPA SHORT WVS...WHICH
WILL INCR CLOUDS AND PRODUCE SCT -SHSN AND AT TIMES HAVE SOME
INTERACTION WITH THE GRTLKS. TEMPS WILL RETURN TO NEAR NORMALS
AFTER A FRIGID CHRISTMAS. TYPICAL WINTER IN UPSTATE NY.
CHRISTMAS NIGHT AND THURS THE FIRST OF THESE SYSTEMS RACES ACROSS
ONTARIO...WITH A FEW WEAK FRONTS AND A 500HPA SHORT WV. MAIN
IMPACTS WILL INCR CLOUDS MAINLY N & W. THU NT IT WILL DRAG A
CDFNT THROUGH WITH SOME -SHSN ACTIVITY MAINLY N & WEST. IN ITS
WAKE FRI CAA AND A 2NDARY CDFNT AND NW FLOW WILL TRIGGER SCT -SHSN
WITH SOME LK ASSISTANCE. WK SFC HIGH BUILDS OVER FCA FRI NT.
SAT ANOTHER WK SHORT WV AND SFC SYSTEM MOVES THROUGH THE GRTLKS
WITH A LITTLE WAA INCRG CLOUDS AND SCT -SHSN IN ECMWF...GETTING SOME
ASSIST FM THE LKS. GFS HAS MORE CLOUDS AND A WIDESPREAD LT -SN OF
MAYBE AN INCH. SAT NT INTO SUN FLOW BCMS ZONAL TO WSW AT 500HPA.
WMFNT AND SFC LOW SETS UP N OF RGN.
NOT MUCH DIFFERENCE BWTN GFS AND ECMWF. WILL POPULATE WITH HPC MID
SHIFT AND TWEAK POPS A TAD. OTHERWISE A QUIET PERIOD FOR THE
HOLIDAY WEEK.
&&
.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
THIS AFTERNOON...FLIGHT CONDITIONS WILL CONTINUE TO DEPEND ON THE
PLACEMENT OF A STALLED FRONTAL BOUNDARY...AND THE DIVIDING LINE
BETWEEN COOLER AND MORE STABLE AIR AND WARMER AND MORE WELL-MIXED
AIR. EXPECT KGFL/KALB TO REMAIN IN PREDOMINATELY IFR FLYING
CONDITIONS...AS MOISTURE AND COOL AIR FUNNELING DOWN THE HUDSON
RIVER VALLEY COMBINED WITH AN EXTREMELY STABLE BOUNDARY LAYER KEEP
FOG AT THESE LOCATIONS. HAVE ADDRESSED A TEMPO GROUP FROM 18Z-20Z AT
KGFL WHERE SUB-FREEZING TEMPERATURES AND PASSING SHOWERS MAY ALLOW
FOR A BRIEF PERIOD OF PATCHY FREEZING DRIZZLE AS WELL.
MEANWHILE...WARMER AND MORE MIXED AIR WILL ALLOW FOR PREDOMINATELY
VFR FLYING CONDITIONS MINUS OCCASIONAL MVFR FROM PASSING SHOWERS AT
KPOU/KPSF. HAVE ADDRESSED THESE WITH TEMPO GROUPS. THE SHOWERS WILL
GRADUALLY END FROM WEST TO EAST BY THIS EVENING. WINDS WILL BE
INITIALLY LIGHT AND VARIABLE AT KGFL/KALB BEFORE BECOMING SOUTHWEST
AROUND 5-10 KNOTS BY THE EARLY EVENING HOURS. SOUTHWEST WINDS WILL
BE AROUND 10 KNOTS AT KPOU AND KPSF...WITH GUSTS UP TO 20-25 KNOTS.
HAVE INCLUDED LLWS AT KGFL AND KALB THROUGH THE AFTERNOON HOURS AS A
STRONG LOW-LEVEL JET MOVES ACROSS THE REGION BEFORE LIFTING TO THE
NORTHEAST THIS EVENING.
TONIGHT INTO MONDAY...DESPITE THE EXPECTED FRONTAL PASSAGE TONIGHT
AND ASSOCIATED MIXING ALONG WITH IT...ABUNDANT RESIDUAL LOW-LEVEL
MOISTURE WILL REMAIN ENTRENCHED ACROSS THE REGION. THE BOUNDARY
LAYER NIGHTTIME PROFILE WILL ALSO CONTINUE TO BE STABLE ALLOWING FOR
PERSISTING IFR FOG AT KGFL/KALB...AND MVFR LOW STRATUS AT
KPOU/KPSF. WINDS WILL BE LIGHT TONIGHT GENERALLY LESS THAN 5 KNOTS.
ANOTHER STORM SYSTEM APPROACHING FROM THE MID-ATLANTIC
WILL PROVIDE THE FOCUS FOR ADDITIONAL ROUNDS OF SHOWERS MAINLY FOR
KPOU/KPSF LATE IN THE TAF PERIOD. WINDS WILL BECOME SOUTHWESTERLY
MONDAY AROUND 5-10 KNOTS.
OUTLOOK...
MONDAY: LOW OPERATIONAL IMPACT. CHANCE OF -SHRAS.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY-FRIDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THOUGH TONIGHT WITH
INCREASING SNOW MELT. LOW PRESSURE WILL MOVE ALONG A NEARLY
STATIONARY FRONT FROM THE NIAGARA FRONTIER TO NEW ENGLAND BY THIS
EVENING. 1-2 INCHES OF ADDITIONAL RAINFALL IS EXPECTED IN THE
ADIRONDACKS...WITH LESSER AMOUNTS SOUTH. TEMPERATURES TODAY WILL WARM
INTO THE 50S AND 60S REMAIN ABOVE FREEZING TONIGHT.
IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT
SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF
INCH...BUT ALMOST ALL THE SNOW WILL MELT. EVEN AS THE RAIN TAPERS
OFF THIS EVENING...SNOW MELT AND RUNOFF WILL CONTINUE TONIGHT.
IN THE SOUTH THE RAINFALL WILL BE SUFFICIENT FOR SIGNIFICANT
WITHIN BANK RISES...BUT FLOODING IS NOT EXPECTED AT THIS TIME.
THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK
VALLEY INTO THE ADIRONDACKS WHERE 1 TO 2 INCHES ADDITIONAL RAIN
AND UP TO AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED.
FLOOD WATCHES REMAIN IN EFFECT THROUGH TONIGHT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
NYZ041>043-083-084.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...FRUGIS/GJM
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...IRL
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS ALBANY NY
1112 AM EST SUN DEC 22 2013
.SYNOPSIS...
A NEARLY STATIONARY FRONT FROM CENTRAL NEW YORK TO THE MAINE COAST
WILL SHIFT SLIGHTLY AS A STORM MOVES ALONG IT TODAY. NORTH OF IT
IT WILL BE CHILLY WITH RAIN AND FREEZING RAIN...WITH RAIN AND VERY
MILD WEATHER TO ITS SOUTH. THE STORM WILL DRAG A COLD FRONT
THROUGH THE REGION TONIGHT AND THEN SLIDE SLOWLY OFFSHORE MONDAY.
HIGH PRESSURE WILL BUILD FROM ONTARIO INTO NEW YORK TUESDAY INTO
CHRISTMAS...WITH MUCH COLDER AIR FILTERING INTO THE REGION. THE
WEEK WILL END WITH A SERIES OF FAST MOVING WEATHER SYSTEMS WITH
BOUTS OF SNOW SHOWERS AND GENERALLY SEASONABLE TEMPERATURES.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1100 AM...HIGHLY VARIABLE CONDITIONS PERSIST ACROSS THE
FORECAST AREA. TEMPS ARE IN THE UPPER 20S TO LOWER 30S FROM THE LAKE
GEORGE SARATOGA REGION INTO THE CAPITAL DISTRICT...IN THE UPPER 30S
TO LOWER 40S IN THE MOHAWK VALLEY...THE ADIRONDACKS AND THE VALLEYS
OF SOUTHERN VERMONT...AND IN THE 50S TO MID 60S ELSEWHERE.
EVENTUALLY EXPECT THE WARM AIR TO ARRIVE IN ALL LOCATIONS...BUT FOR
NOW HAVE ADJUSTED THE HOURLY TEMPS/DEWPOINTS TO REFLECT CURRENT
CONDITIONS...AND ALSO LOWERED MAX TEMPS BY AROUND 10 DEGREES IN
THOSE AREAS WERE THE LOW-LEVEL COLD AIR STILL PERSISTS.
WITH TEMPS NOT MOVING MUCH WHERE THE LOW-LEVEL COLD AIR STILL
LINGERS...HAVE EXTENED THE FREEZING RAIN ADVISORY IN THE LAKE GEORGE
SARATOGA REGION THROUGH 200 PM. PCPN HAS BECOME INTERMITENT AND
LIGHT SO ADDITIONAL ICE ACCUMULATIONS WILL GENERALLY BE UNDER A
TENTH OF AN INCH.
WITH THE NEXT UPDATE WILL CONSIDER DROPPING THE FLOOD WATCH SINCE IT
APPEARS LIKELY THAT ADDITIONAL RAINFALL TODAY WILL BE FAIRLY LIGHT.
.PREVIOUS DISCUSSION...
AS OF 635 AM EST...WIDE VARIETY OF TEMPERATURES ACROSS THE REGION
THIS MORNING WITH STALLED FRONTAL BOUNDARY SITUATED DIRECTLY
ACROSS THE CENTRAL PORTION OF THE CWA. NORTH OF THE
BOUNDARY...VERY COLD CANADIAN AIR IS BEING PULLED SOUTHWARD THANKS
TO A LOW LEVEL NNE FLOW THROUGH THE CHAMPLAIN VALLEY AND INTO THE
HUDSON VALLEY REGION. THIS HAS ALLOWED TEMPS TO DROP BELOW
FREEZING FOR THE GLENS FALLS AND SARATOGA SPRINGS AREA. TEMPS HAVE
FALLEN INTO THE LOW TO MID 30S IN THE CAPITAL REGION.
AT THE SAME TIME...VERY WARM TEMPS ALOFT ARE IN PLACE THANKS TO A
STRONG SOUTHERLY FLOW. AS A RESULT...SOME OF THE WARMER TEMPS AT THIS
HOUR ARE ACROSS THE MOUNTAIN PEAKS OF THE CATSKILLS...SRN GREENS
AND BERKSHIRES...WHERE TEMPS ARE WELL INTO THE 50S. ALSO...A
SOUTHERLY LOW LEVEL WIND COMING UP THE MID HUDSON VALLEY HAS
ALLOWED SOME WARMER AIR TO MOVE TOWARDS POUGHKEEPSIE AND
HUDSON...WITH SFC TEMPS HAVING JUMPED UP INTO THE LOW 60S! THE
JUST LAUNCHED 12Z KALY SOUNDING SHOWS THE COLD SFC LAYER IS ONLY
ABOUT 200 METERS THICK...WITH A WARM NOSE OF ABOUT +16 C AT 850 HPA.
WITH AN APPROACHING LOW PRESSURE AREA AND THE SFC BOUNDARY IN
PLACE...OVERRUNNING PRECIP HAS MOVED TO THE NORTH OF THE
REGION...FALLING AS FZRA/PL ACROSS THE BTV CWA. RIGHT NOW...MUCH
OF OUR CWA IS IN A DRY SLOT...WITH JUST SOME SPOTTY FREEZING RAIN
ACROSS THE SOUTHEASTERN ADIRONDACKS...AND SOME LIGHT RAIN SHOWERS
ACROSS WESTERN NEW ENGLAND. THE LATEST 08Z 3KM HRRR SHOWS THIS DRY
SLOT SHOULD START TO FILL IN TOWARDS THE MID MORNING AS THE LOW
PRESSURE AREA MOVES NORTHEAST ACROSS THE OHIO VALLEY AND
EVENTUALLY TOWARDS UPSTATE NY. RIGHT NOW...WE WILL HOLD CHC POPS
FOR THE NEXT FEW HOURS ACROSS CENTRAL/SOUTHERN PARTS OF THE
AREA...WITH LIKELY/CATEGORICAL POPS ACROSS THE FAR NORTH NEAR THE
BTV CWA BORDER. BY THE LATE MORNING...WE WILL RISE POPS TO
LIKELY/CATEGORICAL FOR WESTERN AND CENTRAL PARTS OF THE CWA AS
WELL.
FOR NOW...IT DOESN/T APPEAR THAT THE CAPITAL REGION WILL BE SEEING
ANY MEASUREABLE FREEZING RAIN...AS THE APPROACHING STORM SHOULD
ALLOW THE STALLED BOUNDARY TO START TO MOVE NORTHWARD AS A WARM
FRONT...AND BRING THE ALBANY AREA INTO THE WARM SECTOR ONCE THE
NEXT ROUND OF RAINFALL BEGINS. ALTHOUGH THERE MAY BE A SPOTTY
SPRINKLE BEFORE THAT OCCURS...IT SHOULDN/T BE ABLE TO ACCRETE MUCH
ICE AT ALL WITH MARGINAL TEMPS AND AN ALREADY WET GROUND.
STILL...WE HAVE PASSED ALONG THE MESSAGE THROUGH OUR SOCIAL MEDIA
CHANNELS THAT WITH TEMPS NEAR FREEZING...SOME WET SURFACES COULD
POTENTIALLY BE SLICK...ALTHOUGH THIS WILL LIKELY BE RATHER SPOTTY.
BASED ON WHATS HAPPENING AT KPOU/1B1...THIS WARMER AIR IS ON THE
MOVE...AND SHOULD WIN OUT OVER THE COLD AIR IN THE CAPITAL REGION
AS THE STRONG STORM SYSTEM MOVES TOWARDS OUR AREA FAIRLY SOON.
HOWEVER...FURTHER NORTH ACROSS THE LAKE GEORGE AREA...IT MAY TAKE
UNTIL THE MID TO LATE MORNING FOR THE WARM FRONT TO MOVE THROUGH
AND TEMPS TO WARM UP. AS A RESULT...A PROLONGED PERIOD OF FREEZING
RAIN CAN BE EXPECTED ACROSS THE LAKE GEORGE SARATOGA REGION. ICE
ACCRETION AMOUNTS WILL RANGE FROM A TRACE TO A TENTH ACROSS THE
SARATOGA SPRINGS AREA TO A FEW TENTHS FOR GLENS FALLS TO ABOUT
FOUR TENTHS ACROSS THE NORTH END OF LAKE GEORGE. ASIDE FROM SOME
HAZARDOUS DRIVING CONDITIONS...THIS MAY LEAD TO SOME ISOLATED
POWER OUTAGES.
AREAS IN THE WARM SECTOR SHOULD SEE SFC TEMPS WARM
SIGNIFICANTLY...AS THOSE WARMER TEMPS ALOFT ARE MIXED IN THE
BOUNDARY LAYER. MAX TEMPS LOOK TO REACH INTO THE 50S ACROSS MUCH OF
THE CENTRAL AND SOUTHERN PARTS OF THE AREA...WITH SOME MID 60S FOR
THE MID HUDSON VALLEY.
WHILE IT WILL RAIN DURING THE MID TO LATE MORNING HOURS...MOST AREAS
WILL BE DONE SEEING PRECIPITATION BY THE EARLY TO MID AFTN
HOURS...AS THE STORM/S COLD FRONT PASSES THROUGH THE AREA. TOTAL
RAINFALL FOR SUNDAY WILL RANGE FROM JUST A QUARTER OF AN INCH
ACROSS LITCHFIELD COUNTY CT...TO AROUND THREE QUARTERS OF AN INCH
IN THE CAPITAL REGION TO ABOUT AN INCH AND A HALF OVER THE
ADIRONDACKS. SEE THE HYDRO SECTION ON HOW WE EXPECT THIS RAINFALL
TO AFFECT AREA RIVERS AND STREAMS.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
FOR THIS PERIOD THE MODEL SUITE (GEM/GFS/ECMWF) ARE IN FAIRLY
GOOD AGREEMENT. DURING THE THIS EVENING THE SFC LOW AND ITS UPPER
DYNAMICS WILL LIFT NE OUT OF FCA. A SERIES OF 500HPA SHORT WAVES
WILL DIG A TROF OVER GRTLKS...MAINTAINING A STRONG SW 500HPA FLOW
OVER THE EASTERN THIRD OF THE NATION. FOR A TIME THIS WILL ACT TO
WEAKEN THE SFC LOW FURTHER OVER NEW ENG...BUT THE SFC LOW WILL
DRAG A CDFNT THROUGH THE REGION TNGT. GIVEN THE UPPER FLOW COOLER
AIR WILL BE SLOW TO FILTER IN OVERNIGHT....AND TEMPS WILL REMAIN
ABV FREEZING IN MOST AREAS...WITH SNOW MELT CONTINUING.
BY MONDAY THIS CDFNT WILL NEARLY STALL ALONG THE EASTERN
SEABOARD...AND WITH DIGGING 500HPA TROF INTERACTING WITH THE COASTAL
BAROCLINIC ZONE WILL TRIGGER A BOUT OF OVERRUNINNG RAIN...ALONG THE
I-95 CORRIDOR THAT WILL BACK BUILD INTO SE PORTIONS OF FCA. QPF
DURING MONDAY WITH THIS SHOULD BE 0.25 TO 0.50 IN THESE AREAS...AND
GIVEN THESE AREAS WERE IN THE WARM SECTOR MUCH OF THE CURRENT
EVENT...THEY MELTED MOST OF THEIR SNOW...BUT HAD LITTLE RAINFALL.
ADD TO THAT THE 2-3 DAYS THIS OCCURRED...THE ADDITIONAL RAIN IN
SOUTHEAST AREAS MONDAY SHOULD NOT RESULT IN ANYTHING OTHER THAN
WITHIN BANK RISES.
FURTHER WEST MONDAY AS HIGH PRESSURE BUILDS EAST WIND GRADIENT
WILL INCR AND AS THE 500HPA TROF PUSHES EAST A MUCH STRONGER 2NDRY
CDFNT WILL PUSH INTO THE REGION LATE MONDAY AND THROUGH MONDAY
NIGHT. TEMPS MONDAY WILL HOLDS STEADY THEN FALL DURING THE AFTN.
MONDAY NIGHT INTO TUES THE PASSAGE OF THE 500HPA TROF...CAA WILL
RESULT IN SCT -SHSN ACTIVITY. HWVR LLVL FLOW WILL BE TOTALLY
UNFAVORABLE FOR LK EFFECT OVER EASTERN NY.
ONCE THE 500HPA TROF EXITS CHRISTMAS EVE BOTH A 500HPA RIDGE...AND
SFC HIGH PRESSURE WILL SETTLE OVER NYS AND MID ATLC REGION. THIS
WILL SET THE STAGE FOR A FRIGID NIGHT WITH IDEAL RADIATIONAL
COOLING...ONE OF THE LONGEST NIGHTS OF THE YEAR...CLEAR SKIES AND
DRY AIR MASS. LOWS WILL PLUNGE TO -20F IN PARTS OF THE ADIRONDACKS
TO AROUND 10 IN THE SE.
TEMPS WILL RECOVER CHRISTMAS DAY TO THE TEENS AND 20S AS SFC HIGH
SLIDES OFFSHORE. SOME CLOUDS MAY ARRIVE IN THE AFTERNOON AS NEXT
WEAK SYSTEM APPROACHES.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
THE EFP WILL FEATURE A SERIES OF FAST MOVING SYSTEMS IN W-NW FLOW.
MOST WILL BE FAIRLY WK CDFNTS AND/OR 500HPA SHORT WVS...WHICH
WILL INCR CLOUDS AND PRODUCE SCT -SHSN AND AT TIMES HAVE SOME
INTERACTION WITH THE GRTLKS. TEMPS WILL RETURN TO NEAR NORMALS
AFTER A FRIGID CHRISTMAS. TYPICAL WINTER IN UPSTATE NY.
CHRISTMAS NIGHT AND THURS THE FIRST OF THESE SYSTEMS RACES ACROSS
ONTARIO...WITH A FEW WEAK FRONTS AND A 500HPA SHORT WV. MAIN
IMPACTS WILL INCR CLOUDS MAINLY N & W. THU NT IT WILL DRAG A
CDFNT THROUGH WITH SOME -SHSN ACTIVITY MAINLY N & WEST. IN ITS
WAKE FRI CAA AND A 2NDARY CDFNT AND NW FLOW WILL TRIGGER SCT -SHSN
WITH SOME LK ASSISTANCE. WK SFC HIGH BUILDS OVER FCA FRI NT.
SAT ANOTHER WK SHORT WV AND SFC SYSTEM MOVES THROUGH THE GRTLKS
WITH A LITTLE WAA INCRG CLOUDS AND SCT -SHSN IN ECMWF...GETTING SOME
ASSIST FM THE LKS. GFS HAS MORE CLOUDS AND A WIDESPREAD LT -SN OF
MAYBE AN INCH. SAT NT INTO SUN FLOW BCMS ZONAL TO WSW AT 500HPA.
WMFNT AND SFC LOW SETS UP N OF RGN.
NOT MUCH DIFFERENCE BWTN GFS AND ECMWF. WILL POPULATE WITH HPC MID
SHIFT AND TWEAK POPS A TAD. OTHERWISE A QUIET PERIOD FOR THE
HOLIDAY WEEK.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
A FRONTAL BOUNDARY WILL BE OVER UPSTATE NY AND NEW ENGLAND TODAY
WITH AREAS OF LOW PRESSURE MOVING ALONG IT. THIS BOUNDARY WILL
DIVIDE VERY COLD AIR FROM UNSEASONABLY MILD AIR OVER THE E-CNTRL NY
CORRIDOR WITH SOME FREEZING RAIN CONTINUING FOR KGFL INTO THE LATE
MORNING...AND SOME SCT SHOWERS FROM KALB-KPSF SOUTHWARD LATE THIS
MORNING INTO THE AFTERNOON. THE BOUNDARY WILL CONTINUE TO LIFT
NORTH...AS A WARM FRONT RAPIDLY THIS MORNING.
FLIGHT CONDITIONS VARY FROM LIFR/IFR AT KGFL/KALB/KPSF TO VFR/MVFR
AT KPOU THIS MORNING. CONDITIONS WILL IMPROVE TO VFR LEVELS AT KPOU
WITH BETTER MIXING...AS THE FRONTAL BOUNDARY LIFTS NORTHWARD. SOME
PATCHY MVFR MIST MAY BE AROUND IN THE LATE MORNING THERE. FURTHER
NORTH...IFR/MVFR CONDITIONS WILL PERSIST INTO THE AFTERNOON WITH
LIGHT FREEZING RAIN TRANSITIONING TO RAIN AT KGFL AT 16Z. MOST OF
THE FLIGHT CONDITIONS THIS AFTERNOON MAY BE IN THE MVFR RANGE...AS
THE FRONT LIFTS NORTH OF ALL THE TERMINALS. SOME DRIZZLE SHOULD
LINGER INTO THIS EVENING...WHICH MAY ALLOW FOR MVFR OR BRIEF PERIODS
OF IFR CIGS/VSBYS AT ALL THE TAF SITES...EXCEPT FOR KALB WHERE LOW
VFR LOOKS POSSIBLE. THE CIGS MAY START TO RISE AROUND MIDNIGHT WITH
SOME DRIER AIR STARTING TO FILTER IN FROM THE SOUTHWEST.
LOW LEVEL WIND SHEAR WILL BE A PROBLEM THIS MORNING AT ALL THE TAF
SITES WITH 2 KFT AGL WINDS FROM THE S/SW AT 45-60 KTS. THE LOW
LEVEL WIND SHEAR LOOKS TO LAST INTO THE EARLY TO MID AFTERNOON AT
THE TERMINALS. THE LOW LEVEL JET STARTS TO LIFT NORTH AND EAST AT
THAT TIME. AT THE SFC...THE WINDS WILL VEER FROM THE EAST OR
NORTHEAST AT KGFL/KALB TO THE SOUTH AT 8-15 KTS WITH SOME GUSTS
CLOSE TO 25 KTS AT KALB AND KPOU. THE WINDS WILL DECREASE FROM THE
S/SW AT LESS THAN 10 KTS AFTER 00Z/MON.
OUTLOOK...
MONDAY: LOW OPERATIONAL IMPACT. CHANCE OF -SHRAS.
MONDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
TUESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
CHRISTMAS DAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHSN.
&&
.HYDROLOGY...
MILD TO UNSEASONABLY WARM TEMPERATURES WILL OCCUR THOUGH TONIGHT WITH
INCREASING SNOW MELT. LOW PRESSURE WILL MOVE ALONG A NEARLY
STATIONARY FRONT FROM THE NIAGARA FRONTIER TO NEW ENGLAND BY THIS
EVENING. 1-2 INCHES OF ADDITIONAL RAINFALL IS EXPECTED IN THE
ADIRONDACKS...WITH LESSER AMOUNTS SOUTH. TEMPERATURES TODAY WILL WARM
INTO THE 50S AND 60S REMAIN ABOVE FREEZING TONIGHT.
IN THE NORTH RAINFALL AMOUNTS WILL BE GREATEST...BUT SNOW MELT
SLOWER...WHILE IN THE SOUTH RAINFALL WILL BE AROUND A HALF
INCH...BUT ALMOST ALL THE SNOW WILL MELT. EVEN AS THE RAIN TAPERS
OFF THIS EVENING...SNOW MELT AND RUNOFF WILL CONTINUE TONIGHT.
IN THE SOUTH THE RAINFALL WILL BE SUFFICIENT FOR SIGNIFICANT
WITHIN BANK RISES...BUT FLOODING IS NOT EXPECTED AT THIS TIME.
THE GREATEST POTENTIAL FOR FLOODING WILL EXIST FROM THE MOHAWK
VALLEY INTO THE ADIRONDACKS WHERE 1 TO 2 INCHES ADDITIONAL RAIN
AND UP TO AN INCH OF LIQUID EQUIVALENT FROM SNOW MELT IS EXPECTED.
FLOOD WATCHES REMAIN IN EFFECT THROUGH TONIGHT.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED
AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE
ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...FREEZING RAIN ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR
NYZ041>043-083-084.
FLOOD WATCH THROUGH MONDAY MORNING FOR NYZ032-033-038>040-042-
043-082.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...SNYDER
NEAR TERM...GJM/FRUGIS
SHORT TERM...SNYDER
LONG TERM...SNYDER
AVIATION...WASULA
HYDROLOGY...SNYDER
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
240 PM EST SUN DEC 22 2013
.UPDATE...
THE LONG TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 249 AM EST SUN DEC 22 2013
A LOW PRESSURE SYSTEM OVER INDIANA WILL QUICKLY PULL NORTHEAST
TODAY TO NEW ENGLAND AS HIGH PRESSURE OVER THE NORTHERN PLAINS
BEGINS TO BUILD ACROSS THE OHIO VALLEY.
COLD NORTH WINDS IN THE WAKE OF THE LOW WILL RESULT IN
TEMPERATURES RETURNING TO BELOW NORMAL FOR THE NEXT FEW
DAYS...HOWEVER THE DRY AIR MASS ASSOCIATED WITH THE HIGH WILL
BRING SIGNIFICANT PRECIPITATION TO AN END.
ANOTHER MUCH WEAKER CLIPPER TYPE SYSTEM WILL MOVE SOUTHEAST INTO
THE GREAT LAKES MIDWEEK PRODUCING SOME LIGHT SNOW FOLLOWED BY
REINFORCING COLD CANADIAN AIR TO END THE UPCOMING WEEK.
&&
.NEAR TERM /TODAY/...
ISSUED AT 1234 PM EST SUN DEC 22 2013
FORECAST REMAINS IN GOOD SHAPE...BUT FELT COMFORTABLE REMOVING
POPS AND ONLY MENTIONING A CHANCE OF FLURRIES GIVEN UPSTREAM
ECHOES OBSERVED THUS FAR AND HRRR PROGS. PREVIOUS DISCUSSION FOLLOWS.
ISSUED AT 249 AM EST SUN DEC 22 2013
SURFACE ANALYSIS EARLY THIS MORNING SHOWS LOW PRESSURE OVER
CENTRAL INDIANA. HIGH PRESSURE WAS FOUND OVER THE NORTHERN PLAINS.
WATER VAPOR IMAGERY SHOWS A LARGE TROUGH OVER THE CENTRAL PART OF
THE UNITED STATES...WITH A DRY SLOT PULLING NORTH INTO THE
MISSISSIPPI RIVER VALLEY . THE TROPICAL PLUME OF MOISTURE WAS
STILL STREAMING INTO ILLINOIS AND INDIANA...BUT WAS PULLING EAST
QUICKLY. RADAR MOSAICS SHOW THE BACK EDGE OF PRECIPITATION HAS MOVED
TO THE EAST OF TERRE HAUTE...VINCENNES AND LAFAYETTE.
MAIN FORECAST CHALLENGE TODAY WILL BE POPS. NAM AND GFS ARE IN
GOOD AGREEMENT THAT THE SURGE OF MOISTURE ASSOCIATED WITH THE
TROPICAL PLUME WILL QUICKLY PULL EAST AND THE BULK OF
PRECIPITATION ACROSS THE AREA WILL END BY 12Z...HOWEVER SEVERAL
LINGERING THINGS STILL EXIST THAT COULD RESULT IN SOME VERY LIGHT
ADDITIONAL PRECIPITATION TODAY.
FIRST OFF...THE NAM AND THE GFS BOTH PUSH YET ANOTHER SHORT WAVE
TOWARD CENTRAL INDIANA IN THE QUICK SW FLOW ALOFT AS THE
DEEP TROUGH OVER THE CENTER OF THE COUNTRY BEGINS TO SLIDE EAST.
LOWER LEVEL FLOW LOOKS TO REMAIN STRONGLY CYCLONIC TODAY AS THE
SURFACE LOW DEPARTS TO THE EAST. FORECAST SOUNDINGS AND TIME HEIGHTS
CONTINUE TO KEEP HIGH RH/S TRAPPED IN THE LOWER LEVELS. THUS WILL
KEEP A SLIGHT CHANCE FOR SOME PRECIP TODAY...RAIN INITIALLY THIS
MORNING...BUT AS STRONG COLD AIR ADVECTION CONTINUES THROUGH THE
AFTERNOON...FORECAST SOUNDINGS FALL BELOW FREEZING THUS PRECIP
TYPE WILL CHANGE TO SNOW BY LATE AFTERNOON.
GIVEN THE STRONG COLD AIR ADVECTION THAT IS EXPECTED IN THE WAKE OF
THE FRONT...TEMPS ARE NOT EXPECTED TO RISE TODAY AND A NON DIURNAL
TEMP CURVE WILL BE USED. WILL TREND HIGHS TOWARD EXPECTED 12Z VALUES.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
ISSUED AT 249 AM EST SUN DEC 22 2013
MAIN FORECAST CHALLENGE DURING THIS PERIOD WILL BE TEMPS AND CLOUDS.
MODELS ARE IN PRETTY GOOD AGREEMENT OVERALL AND WILL USE A BLEND.
GFS AND NAM SUGGEST THE LARGE UPPER TROUGH WILL VERY SLOWLY PUSH
EAST INTO THE OHIO VALLEY TONIGHT BEFORE FINALLY EXITING THE
AREA ON TUESDAY NIGHT. MEANWHILE AT THE SURFACE STRONG COLD AIR
ADVECTION WILL CONTINUE ACROSS INDIANA ON NORTHERLY WINDS AS 850MB
TEMPS FALL TO -15C TO -18C DEPENDING UPON YOUR FAVORITE MODEL.
FORECAST SOUNDINGS SHOW DEEP MOISTURE REMAINS UNAVAILABLE...YET
THE LOWER LEVEL FLOW LOOKS TO REMAIN BROADLY CYCLONIC. FORECAST
SOUNDINGS ARE ENTIRELY BELOW ZERO THROUGH TUESDAY NIGHT. FORECAST
SOUNDINGS CONTINUE TO KEEP TRAPPED LOWER LEVEL MOISTURE ACROSS THE
AREA...THROUGH MONDAY NIGHT AMID SUBSIDENCE ALOFT. THUS GIVEN ALL
OF THIS WILL KEEP A SLIGHT CHANCE FOR SNOW SHOWERS OR FLURRIES
THROUGH MONDAY NIGHT.
GFS AND NAM PULL THE LARGE UPPER TROUGH WELL EAST OF INDIANA ON
TUESDAY AS ANTICYCLONIC LOWER LEVEL FLOW BEGINS. THUS WILL TREND
TOWARD A CLEAR SKY ON TUESDAY AND TUESDAY NIGHT WITH HIGH PRESSURE
ACROSS THE AREA.
AS FOR TEMPS GIVEN THE STRONG COLD AIR ADVECTION THROUGH THE
PERIOD WILL TREND HIGHS AND LOWS COOLER THAN THE MAVMOS GUIDANCE
THROUGH THE PERIOD.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
ISSUED AT 240 PM EST SUN DEC 22 2013
NO MAJOR WEATHER CONCERNS FOR THE EXTENDED WHICH SHOULD ALLOW RIVER
FLOODING TO RUN ITS COURSE. THAT BEING SIAD...MODELS IN GENERAL
AGREEMENT THAT TWO DIFFERENT SYSTEMS WILL BRING POTENTIAL FOR MINOR
PRECIPITATION WEDNESDAY NIGHT AND THURSDAY AS WELL AS SUNDAY.
SO...KEPT SMALL REGIONAL ALLBLEND POPS. IT SHOULD BE COLD ENOUGH FOR
ONLY SNOW AS PRECIPITATION TYPE WEDNESDAY NIGHT AND THURSDAY...BUT
SOUTHWEST FLOW AHEAD OF LATE WEEKEND FRONTAL SYSTEM SUGGESTS
POSSIBILITY EXISTS OF A MIX OF RAIN AND SNOW IF NOT JUST RAIN.
ALLBLEND TEMPERATURES LOOK REASONABLE WITH AFTERNOON TEMPERATURES
STARTING OFF IN THE 20S AND 30S AND THEN WARMING TO THE 30S AND 40S
BY SATURDAY.
&&
.AVIATION /DISCUSSION FOR 221800Z TAF ISSUANCE/...
ISSUED AT 1200 PM EST SUN DEC 22 2013
CONDITIONS EXPECTED TO IMPROVE TO MVFR ACROSS THE TAF SITES AT OR
SHORTLY AFTER ISSUANCE TIME AND VFR AFTER 15Z MONDAY BASED ON BASED
ON MODEL TIME SECTIONS. BASED ON CU DEVELOPMENT PROGS...HUF AND BMG
SHOULD ONLY SEE SCATTERED CU TOMORROW WITH IND AND LAF EXPECTED TO
SEE CEILINGS. CONFIDENCE IS GOOD REGARDING LIGHT CATEGORIES OVERALL.
HOWEVER...WOULD NOT RULE OUT BRIEF IFR AT THE ONSET AND POSSIBLY
BRIEF MID DAY MVFR CU MONDAY. WOULD NOT RULE OUT A BRIEF LIGHT RAIN
SHOWER THIS AFTERNOON AND SNOW SHOWER TONIGHT AND MONDAY...BUT
CHANCES TOO LOW TO MENTION.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...PUMA
NEAR TERM...PUMA/NIELD
SHORT TERM...PUMA
LONG TERM....CP
AVIATION...MK
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1234 PM EST SUN DEC 22 2013
.UPDATE...
THE NEAR TERM SECTION HAS BEEN UPDATED BELOW.
&&
.SYNOPSIS...
ISSUED AT 249 AM EST SUN DEC 22 2013
A LOW PRESSURE SYSTEM OVER INDIANA WILL QUICKLY PULL NORTHEAST
TODAY TO NEW ENGLAND AS HIGH PRESSURE OVER THE NORTHERN PLAINS
BEGINS TO BUILD ACROSS THE OHIO VALLEY.
COLD NORTH WINDS IN THE WAKE OF THE LOW WILL RESULT IN
TEMPERATURES RETURNING TO BELOW NORMAL FOR THE NEXT FEW
DAYS...HOWEVER THE DRY AIR MASS ASSOCIATED WITH THE HIGH WILL
BRING SIGNIFICANT PRECIPITATION TO AN END.
ANOTHER MUCH WEAKER CLIPPER TYPE SYSTEM WILL MOVE SOUTHEAST INTO
THE GREAT LAKES MIDWEEK PRODUCING SOME LIGHT SNOW FOLLOWED BY
REINFORCING COLD CANADIAN AIR TO END THE UPCOMING WEEK.
&&
.NEAR TERM /TODAY/...
ISSUED AT 1234 PM EST SUN DEC 22 2013
FORECAST REMAINS IN GOOD SHAPE...BUT FELT COMFORTABLE REMOVING
POPS AND ONLY MENTIONING A CHANCE OF FLURRIES GIVEN UPSTREAM
ECHOES OBSERVED THUS FAR AND HRRR PROGS. PREVIOUS DISCUSSION FOLLOWS.
ISSUED AT 249 AM EST SUN DEC 22 2013
SURFACE ANALYSIS EARLY THIS MORNING SHOWS LOW PRESSURE OVER
CENTRAL INDIANA. HIGH PRESSURE WAS FOUND OVER THE NORTHERN PLAINS.
WATER VAPOR IMAGERY SHOWS A LARGE TROUGH OVER THE CENTRAL PART OF
THE UNITED STATES...WITH A DRY SLOT PULLING NORTH INTO THE
MISSISSIPPI RIVER VALLEY . THE TROPICAL PLUME OF MOISTURE WAS
STILL STREAMING INTO ILLINOIS AND INDIANA...BUT WAS PULLING EAST
QUICKLY. RADAR MOSAICS SHOW THE BACK EDGE OF PRECIPITATION HAS MOVED
TO THE EAST OF TERRE HAUTE...VINCENNES AND LAFAYETTE.
MAIN FORECAST CHALLENGE TODAY WILL BE POPS. NAM AND GFS ARE IN
GOOD AGREEMENT THAT THE SURGE OF MOISTURE ASSOCIATED WITH THE
TROPICAL PLUME WILL QUICKLY PULL EAST AND THE BULK OF
PRECIPITATION ACROSS THE AREA WILL END BY 12Z...HOWEVER SEVERAL
LINGERING THINGS STILL EXIST THAT COULD RESULT IN SOME VERY LIGHT
ADDITIONAL PRECIPITATION TODAY.
FIRST OFF...THE NAM AND THE GFS BOTH PUSH YET ANOTHER SHORT WAVE
TOWARD CENTRAL INDIANA IN THE QUICK SW FLOW ALOFT AS THE
DEEP TROUGH OVER THE CENTER OF THE COUNTRY BEGINS TO SLIDE EAST.
LOWER LEVEL FLOW LOOKS TO REMAIN STRONGLY CYCLONIC TODAY AS THE
SURFACE LOW DEPARTS TO THE EAST. FORECAST SOUNDINGS AND TIME HEIGHTS
CONTINUE TO KEEP HIGH RH/S TRAPPED IN THE LOWER LEVELS. THUS WILL
KEEP A SLIGHT CHANCE FOR SOME PRECIP TODAY...RAIN INITIALLY THIS
MORNING...BUT AS STRONG COLD AIR ADVECTION CONTINUES THROUGH THE
AFTERNOON...FORECAST SOUNDINGS FALL BELOW FREEZING THUS PRECIP
TYPE WILL CHANGE TO SNOW BY LATE AFTERNOON.
GIVEN THE STRONG COLD AIR ADVECTION THAT IS EXPECTED IN THE WAKE OF
THE FRONT...TEMPS ARE NOT EXPECTED TO RISE TODAY AND A NON DIURNAL
TEMP CURVE WILL BE USED. WILL TREND HIGHS TOWARD EXPECTED 12Z VALUES.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
ISSUED AT 249 AM EST SUN DEC 22 2013
MAIN FORECAST CHALLENGE DURING THIS PERIOD WILL BE TEMPS AND CLOUDS.
MODELS ARE IN PRETTY GOOD AGREEMENT OVERALL AND WILL USE A BLEND.
GFS AND NAM SUGGEST THE LARGE UPPER TROUGH WILL VERY SLOWLY PUSH
EAST INTO THE OHIO VALLEY TONIGHT BEFORE FINALLY EXITING THE
AREA ON TUESDAY NIGHT. MEANWHILE AT THE SURFACE STRONG COLD AIR
ADVECTION WILL CONTINUE ACROSS INDIANA ON NORTHERLY WINDS AS 850MB
TEMPS FALL TO -15C TO -18C DEPENDING UPON YOUR FAVORITE MODEL.
FORECAST SOUNDINGS SHOW DEEP MOISTURE REMAINS UNAVAILABLE...YET
THE LOWER LEVEL FLOW LOOKS TO REMAIN BROADLY CYCLONIC. FORECAST
SOUNDINGS ARE ENTIRELY BELOW ZERO THROUGH TUESDAY NIGHT. FORECAST
SOUNDINGS CONTINUE TO KEEP TRAPPED LOWER LEVEL MOISTURE ACROSS THE
AREA...THROUGH MONDAY NIGHT AMID SUBSIDENCE ALOFT. THUS GIVEN ALL
OF THIS WILL KEEP A SLIGHT CHANCE FOR SNOW SHOWERS OR FLURRIES
THROUGH MONDAY NIGHT.
GFS AND NAM PULL THE LARGE UPPER TROUGH WELL EAST OF INDIANA ON
TUESDAY AS ANTICYCLONIC LOWER LEVEL FLOW BEGINS. THUS WILL TREND
TOWARD A CLEAR SKY ON TUESDAY AND TUESDAY NIGHT WITH HIGH PRESSURE
ACROSS THE AREA.
AS FOR TEMPS GIVEN THE STRONG COLD AIR ADVECTION THROUGH THE
PERIOD WILL TREND HIGHS AND LOWS COOLER THAN THE MAVMOS GUIDANCE
THROUGH THE PERIOD.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
ISSUED AT 325 AM EST SUN DEC 22 2013
A WEAK CLIPPER SYSTEM WILL MOVE THROUGH CENTRAL INDIANA EARLY IN THE
LONG TERM. THERE WILL BE VERY LITTLE MOISTURE FOR THE SYSTEM TO WORK
WITH AND LITTLE IN THE WAY OF SURFACE FORCING. STILL CAN/T RULE OUT
ONE OR TWO TENTHS OF AN INCH OF SNOW GIVEN THE UPPER WAVE...SO WILL
KEEP SLIGHT CHANCES FOR SNOW FROM WEDNESDAY THROUGH THURSDAY. BY
THURSDAY NIGHT UPPER RIDGING MOVES IN AND SURFACE HIGH PRESSURE
REESTABLISHES ITSELF AND DRY WEATHER WILL ENSUE. STILL SOME
DISAGREEMENTS BETWEEN THE GFS AND ECMWF ON TIMING OF THE ARRIVAL OF
COLD AIR SHOTS BUT SAW NO REASON TO DEVIATE FROM ALLBLEND WHICH
REPRESENTS A GOOD COMPROMISE.
&&
.AVIATION /DISCUSSION FOR 221800Z TAF ISSUANCE/...
ISSUED AT 1200 PM EST SUN DEC 22 2013
CONDITIONS EXPECTED TO IMPROVE TO MVFR ACROSS THE TAF SITES AT OR
SHORTLY AFTER ISSUANCE TIME AND VFR AFTER 15Z MONDAY BASED ON BASED
ON MODEL TIME SECTIONS. BASED ON CU DEVELOPMENT PROGS...HUF AND BMG
SHOULD ONLY SEE SCATTERED CU TOMORROW WITH IND AND LAF EXPECTED TO
SEE CEILINGS. CONFIDENCE IS GOOD REGARDING LIGHT CATEGORIES OVERALL.
HOWEVER...WOULD NOT RULE OUT BRIEF IFR AT THE ONSET AND POSSIBLY
BRIEF MID DAY MVFR CU MONDAY. WOULD NOT RULE OUT A BRIEF LIGHT RAIN
SHOWER THIS AFTERNOON AND SNOW SHOWER TONIGHT AND MONDAY...BUT
CHANCES TOO LOW TO MENTION.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...PUMA
NEAR TERM...PUMA/NIELD
SHORT TERM...PUMA
LONG TERM....CP
AVIATION...MK
VISIT US AT HTTP://WWW.WEATHER.GOV/IND
FOLLOW US ON TWITTER AND YOUTUBE AT:
WWW.TWITTER.COM/NWSINDIANAPOLIS
WWW.YOUTUBE.COM/NWSINDIANAPOLIS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
300 PM EST SUN DEC 22 2013
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 259 PM EST SUN DEC 22 2013
WATER VAPOR LOOP AND RUC ANALYSIS SHOWS SHORTWAVE AND ASSOC LOW
PRESSURE SYSTEM LIFTING NE THROUGH THE LOWER GREAT LAKES. WEAKENING
LIFT AS NOTED ON MID-LVL Q-VECT ANALYSIS AND EVENTUAL TRANSITION TO
Q-VECT DIVERGENCE HAS QUICKLY DIMINISHED SYSTEM SNOW OVER THE EAST
HALF OF UPPER MI THIS AFTERNOON. TOTAL SYSTEM SNOW ACCUMULATIONS
ACROSS THE SCNTRL AND ERN COUNTIES IN THE WINTER WX ADVISORY AREA
WILL LIKELY END UP IN THE 2 TO 3 INCH RANGE WITH A FEW SPOTS LOCALLY
RECEIVING 4 INCHES. SNOW RATIOS APPEAR TO BE LOWER THAN EXPECTED IN
PREV FCST LEADING TO DIMINISHED SNOW AMTS. SNOWFLAKES HERE AT NWS
MQT ARE QUITE SMALL LEADING TO 6/1 SLR ON THE 18Z. DESPITE
DIMINISHED SNOW AMTS...SMALL FLAKES ARE RESULTING IN REDUCED VSBYS.
SOME ACCIDENTS ALSO REPORTED IN MENOMINEE COUNTY FROM SLIPPERY ROADS
THIS AFTERNOON.
WITH SYSTEM SNOW BASICALLY DONE THIS AFTERNOON...FOCUS WILL SHIFT TO
LES WHICH IS EXPECTED TO IMPACT MAINLY WEST AND NCNTRL COUNTIES
TONIGHT INTO MONDAY EVENING IN NE FLOW.
GRADUALLY COLDER 8H TEMPS MOVING IN FM THE WEST BEHIND DEPARTED LOW
SHOULD ALLOW SNOW RATIOS TO INCREASE THROUGH TONIGHT TO NEAR 20/1
WEST AND NCNTRL AS NOTED ON BUFKIT SNDG DATA. THE INCREASED
INSTABILITY WITH COLDER OVER-WATER TEMPS ALONG WITH DEEPER MOISTURE
AND ENHANCEMENT POTENTIAL FROM APPROACHING MID-LVL TROUGH FM THE NRN
PLAINS SHOULD ALLOW FOR AN UPTICK IN LAKE EFFECT SNOW AMTS TONIGHT
INTO MONDAY FOR FAR WEST AND NCNTRL COUNTIES. NO BIG CHANGES
EXPECTED WITH FORECAST AS LES ADVISORIES STILL LOOK GOOD FOR
GOGEBIC-ONTONAGON AND BARAGA-MARQUETTE COUNTIES HIGHLIGHTING STORM
TOTAL SNOWFALL AMOUNTS POSSIBLY APPROACHING A FOOT OVER THE HIGHER
TERRAIN AREAS FROM NORTH OF KIWD TO THE PORCUPINE MOUNTAINS AND FROM
HERMAN THROUGH HURON MOUNTAINS TO NEGAUNEE. BIGGEST CONCERN OVER THE
WRN COUNTIES IS THAT LES AMOUNTS MAY BE LESS THAN ORIGINALLY
EXPECTED IN IWD AREA AS MODELS APPEAR TO BE HANGING ON TO THE NE
FLOW A BIT LONGER THROUGH TONIGHT WHICH MAY PUSH THE BEST LOW-LVL
CONVERGENCE AND THUS DOMINANT LES BANDS WEST OF KIWD. LES SHOULD
EVENTUALLY PICK UP OVER THE FAR WEST BY MONDAY AFTERNOON AS WINDS
BACK FM NE TO NNE BUT INITIAL LACK OF MODERATE SNOW COULD LIMIT
STORM AMOUNTS IN THE KIWD AREA TO CLOSER TO 8 INCHES. PORCUPINE
MOUNTAINS COULD STILL SEE TOTALS APPROACHING A FOOT THROUGH THE
EVENT.
AS MID-LVL TROUGH AXIS MOVES OVERHEAD LATE MON AFTERNOON...MODELS
SHOW Q-VECT CONV DIMINISHING WHICH SHOULD LIMIT ENHANCEMENT
POTENTIAL AT THAT TIME AND ALLOW FOR LES TO SLOWLY DIMINISH FROM
WEST TO EAST INTO MON EVENING.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 259 PM EST SUN DEC 22 2013
THE UPPER TROUGH AXIS WILL BE OVER CENTRAL UPPER MI AT 00Z
TUE...EXITING E BY 06Z TUE AS AN UPPER RIDGE MOVES TOWARD THE CWA
FROM THE NW. THE RIDGE AXIS MOVES TO THE CENTRAL CWA BY 00Z WED. THE
12Z/22 NAM IS NOT AS STRONG OR AS FAST WITH THE RIDGE THAN THE
GFS/ECMWF/GLOBAL GEM...AND ALSO HAS THE SFC TROUGH BEING STRONGER
WITH A MESO LOW OVER SCENTRAL LAKE SUPERIOR EVEN AFTER THE RIDGE
MOVES OVER. THINK THE SFC TROUGH WILL BE STRONGER THAN THE LARGER
SCALE MODELS SHOW IT...BUT NOT AS STRONG AS THE NAM. EXPECT ONGOING
LES AT THE START OF THE PERIOD TO TAPER OFF THROUGH MON NIGHT INTO
TUE MORNING. GENERALLY...2-4 INCHES OF SNOW CAN BE EXPECTED MON
NIGHT OVER THE HIGHER TERRAIN OF NCENTRAL UPPER MI...WITH OTHER
AREAS NEAR LAKE SUPERIOR SEEING 1-2 INCHES.
MODELS ARE IN GOOD AGREEMENT THAT A SHORTWAVE WILL BRING A QUICK /6
HOUR OR LESS DURATION/ COUPLE OF INCHES OF SNOW TO WEST AND CENTRAL
UPPER MI TUE NIGHT. AS THE SHORTWAVE MOVES ACROSS THE ERN U.P.
CHRISTMAS MORNING...SSE LOW LEVEL WINDS AND 850MB TEMPS AROUND -14C
WILL ALLOW FOR LAKE ENHANCEMENT OFF LAKE MICHIGAN. COULD SEE
ADVISORY LEVEL SNOW AMOUNTS IN EXCESS OF 6 INCHES IN AROUND 12
HOURS. COLDER AIR COMES IN WITH NW LOW LEVEL WINDS LATER CHRISTMAS
DAY...LEADING TO NW WIND LES THAT WILL PERSIST UNTIL A RIDGE PASSES
THU NIGHT INTO FRI. THE CWA MAY SEE ADDITIONAL LIGHT AREA WIDE SNOW
FROM A SHORTWAVE THAT SOME MODELS SHOW MOVING THROUGH...BUT
IF...WHEN AND WHERE ARE QUESTIONS THAT MAKE THIS VERY UNCERTAIN.
ALTHOUGH CONFIDENCE DECREASES FARTHER OUT IN THE FORECAST
PERIOD...MODELS DO GENERALLY AGREE ON MODERATING TEMPERATURES ON SAT
AS A SHORTWAVE MOVES THROUGH THE REGION...WITH TEMPERATURES TURNING
COLDER FOR NEXT SUN. RAN WITH A GENERAL CONSENSUS OF MODEL GUIDANCE
FOR THIS PART OF THE FORECAST.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1252 PM EST SUN DEC 22 2013
WITH NE WINDS AND PLENTY OF LOW LEVEL MOISTURE AVAILABLE...MVFR CIGS
SHOULD PREVAIL AT ALL THREE TAF SITES THROUGH MUCH OF THE FCST PD.
VISIBILITIES HAVE DECREASED TO IFR TODAY AT KCMX AND KSAW WITH THE
FINE-FLAKED SYSTEM SNOW SPREADING INTO THE REGION. AS SYSTEM SNOW
EXITS EAST THIS EVENING EXPECT A TRANSITION TO LAKE EFFECT SNOW
ACROSS THE AREA. PREVAILING VSBYS SHOULD REMAIN IN THE IFR RANGE
ESPECIALLY AS FLOW BACKS FROM NE TO NNE ON MONDAY MORNING.
&&
.MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 259 PM EST SUN DEC 22 2013
NORTHEAST WINDS UP TO 30 KNOTS OVER WEST AND NORTH CENTRAL LAKE
SUPERIOR WILL GRADUALLY DIMINISH THROUGH THE AFTERNOON/EARLY EVENING
...BUT GUSTS TO AROUND 25 KNOTS WILL CONTINUE INTO MONDAY. THESE
WINDS ALONG WITH FALLING TEMPS THIS AFTERNOON/EVENING WILL PRODUCE
HEAVY FREEZING SPRAY TODAY THROUGH MONDAY WHEN THE WINDS FINALLY
SLACKEN. WINDS BEGIN TO INCREASE ONCE AGAIN TUESDAY NIGHT INTO
WEDNESDAY AS THE NEXT SYSTEM PASSES TO THE NORTH OF LAKE SUPERIOR.
GALE FORCE GUSTS OVER 35 KNOTS ARE POSSIBLE OVER EASTERN LAKE
SUPERIOR TUESDAY NIGHT AND EARLY WEDNESDAY MORNING. WINDS GRADUALLY
DIMINISH ONCE AGAIN WEDNESDAY NIGHT INTO FRIDAY AS HIGH PRESSURE
STARTS TO BUILD INTO THE REGION.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ007-
013-014-085.
LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT EST /11 PM CST/ MONDAY
NIGHT FOR MIZ002-009.
WINTER WEATHER ADVISORY UNTIL 2 PM CST THIS AFTERNOON FOR MIZ012.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST TUESDAY FOR MIZ004-005.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST /NOON CST/ MONDAY
FOR LSZ162-263-264.
LAKE MICHIGAN...
NONE.
&&
$$
SHORT TERM...VOSS
LONG TERM...TITUS
AVIATION...VOSS
MARINE...VOSS
AREA FORECAST DISCUSSION
NWS ELKO NV
1223 PM PST SUN DEC 22 2013
.SYNOPSIS...DRY QUIET WEATHER WILL PREVAIL ACROSS MOST OF NEVADA
FOR MOST OF THIS WEEK.
&&
.UPDATE...UPDATED TEMPERATURE GRIDS FOR THIS AFTERNOON, RAISING
MAX TEMPS CLOSE TO CURRENT READINGS IN THE UPPER 30S AND LOWER
40S. BAT
&&
.PREV DISCUSSION... /ISSUED AT 329 AM /
SYNOPSIS...LINGERING PACIFIC MOISTURE WILL IMPACT PORTIONS OF
ELKO COUNTY TODAY POTENTIALLY RESULTING IN FLURRIES. BIG PICTURE
WISE...WIDESPREAD NORTHERLY FLOW WILL BE REPLACED BY RIDGING.
EXPECTING INVERSIONS TO DEVELOP OVER THE VALLEYS WHICH WILL BRING
THE SINGLE DIGIT TEMPERATURES BACK. OTHER THAN THE COLD SNAP OVER
NORTHERN NEVADA...GENERALLY EXPECTING MILD CONDITIONS FOR
CHRISTMAS AND THROUGH FRIDAY.
SHORT TERM...TODAY THROUGH TUESDAY. THE PROGGED SOUNDING FOR ELKO
CONTINUES TO DEPICT SATURATION OR NEAR SATURATION...WHICH IS
CONSISTENT WITH THE RECENT SNOW MELT AND MOISTURE ADVECTION FROM
THE PACIFIC SYSTEM. THE GFS PINGS INTO NEAR 90 PERCENT RH FROM 700 MB
TO 500 MB OVER THE NORTHERN ZONES OF LKN THROUGH 18Z TODAY.
MEANWHILE...THE NAM AND RUC TAKE IT ONE STEP FURTHER BRINGING SNOW
INTO THE NORTHERN HALF OF ELKO COUNTY. FLURRIES WILL BE POSSIBLE
IN THE JARBIDGE WILDERNESS AREA AND JACKPOT...BUT MOST OF THE
REGION WILL BE UNEVENTFUL. IN THE WAKE OF THE EXTENSIVE MELTING
THAT OCCURRED SATURDAY AFTERNOON...THERE HAS BEEN MUCH DISCOURSE OVER THE
POTENTIAL FOR THE DEVELOPMENT OF FREEZING FOG THIS MORNING. KEPT
PATCHY FREEZING FOG IN THE GRIDS.
LONG TERM...CHRISTMAS EVE THROUGH NEXT SATURDAY. QUIET WEATHER
CAN BE EXPECTED ACROSS THE WESTERN GREAT BASIN THROUGH CHRISTMAS
WEEK. THE HOLIDAY WEEK BEGINS WITH A WEAK NORTHWEST FLOW IN PLACE
ACROSS THE GREAT BASIN. AS THE WEEK CONTINUES A WEAK TROUGH SLIDES
SOUTHEAST WITHIN THE NORTHWEST FLOW ALOFT ACROSS THE GREAT BASIN
ON CHRISTMAS DAY. SINCE THIS TROUGH IS MOISTURE STAVED AND
POSITIVELY TILTED...NOTHING MORE THAN A FEW CLOUDS CAN BE EXPECTED
MAINLY OVER NORTHERN AREAS.
FOLLOWING THIS TROUGH...A STRONG RIDGE OVER THE EASTERN PACIFIC WILL
BUILD INTO THE WESTERN STATES CONTINUING DRY AND COLD CONDITIONS.
MODEL SOUNDINGS BENEATH THIS RIDGE INDICATE A STRONG INVERSION WILL
BE IN PLACE MAINLY ESPECIALLY OVER NORTHERN AREAS. STRONG
RADIATIONAL COOLING ESPECIALLY IN SNOW COVER AREAS WILL DROP
TEMPERATURES INTO THE SINGLE DIGITS AT NIGHT. RECOVERY DURING THE
DAY WILL BE LIMITED WITH THE STRONG INVERSION IN PLACE...SO EXPECT
MAXIMUM TEMPERATURES TO REBOUND INTO THE UPPER 20S/LOWER 30S IN MANY
VALLEY AREAS. THE HIGHER ELEVATIONS ABOVE THE INVERSION WITH SEE
TEMPERATURES IN THE 30S AND 40S. THE RIDGE GRADUALLY WILL BREAKDOWN
DURING FRIDAY ALLOWING A TROUGH TO APPROACH FROM THE NORTHWEST WITH
SOME MOISTURE FOR MAINLY NORTHERN AREAS ON SATURDAY.
AVIATION...WITH ABUNDANT LOW LEVEL MOISTURE IN PLACE FROM RAPID
SNOWMELT SATURDAY...FOG AND LOW CIGS BECOMES THE CONCERN FOR MAINLY
THE NORTHERN AND EASTERN TAF LOCATIONS. WITH THE NEW AVIATION
PACKAGE PLAN TO MENTION VCFG AT KWMC/KEKO/KELY THIS MORNING AND A
COMBINATION OF MVFR/VFR CIGS THROUGH THE DAY. KTPH SHOULD BE IN
BETTER SHAPE WITH SKC CONDITIONS.
&&
.LKN WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS LUBBOCK TX
1141 AM CST SUN DEC 22 2013
.AVIATION...
NO THREAT TO VFR CONDITIONS THROUGH MONDAY AS SURFACE HIGH
PRESSURE PASSES THROUGH THE REGION. LIGHT NLY WINDS TODAY WILL
VEER S-SWLY BY TONIGHT.
&&
PREV DISCUSSION... /ISSUED 331 AM CST SUN DEC 22 2013/
SHORT TERM...
WINTER DOES NOT WANT TO LET UP FOR THE REGION WITH RENEWED CHANCES
FOR LIGHT PRECIPITATION THIS MORNING. ANOTHER TROUGH AXIS HAS STILL
TO PASS LATER THIS MORNING. WEAK Q-VECTOR CONVERGENCE IS CURRENTLY
MOVING OVER THE AREA. THIS WAS COUPLED WITH WEAK FRONTOGENETICAL
FORCING AROUND 750-700MB EDGING INTO THE SOUTHWESTERN TEXAS
PANHANDLE. MODELS WERE IN GOOD AGREEMENT SHOWING LIFT PEAKING AROUND
12Z UNDER SATURATED SOUNDINGS. ALTHOUGH...THE ONLY DIFFERENCE
BETWEEN MODEL RAP AND NAM SOUNDINGS IS A DRY NEAR SURFACE LAYER
DEPICTED BY THE NAM. THIS CAN CERTAINLY MAKE A DIFFERENCE IN SNOW
TOTALS WITH THE MORE MOIST RAP SHOWING MORE SNOWFALL.
LONG TERM...
WITH THE EXIT EAST OF THE CURRENT LONG-WAVE TROUGH MONDAY...LESSER
AMPLITUDE AND DRY NORTHWEST FLOW WILL BECOME DOMINANT THROUGH MUCH
OF THE WEEK. NEXT SHORT-WAVE UPPER TROUGH WILL SKIM BY TO THE
NORTH WEDNESDAY DRAGGING A SLIGHTLY WEAKER FRONT INTO THE AREA
EARLY WEDNESDAY THAN PREVIOUSLY ADVERTISED. FLATTER WESTERLY FLOW
APPEARS IN THE WORKS EARLY NEXT WEEKEND WITH BACKING AND INCREASING
SOUTHWEST FLOW ALOFT LATER IN THE WEEKEND...ALTHOUGH SPREAD IN THE
DEVELOPING INTER-MOUNTAIN UPPER TROUGH WILL BE ON THE RISE. THIS
PATTERN WILL YIELD MODEST WARMING MONDAY...A WEAK BACK-DOOR FRONT
WILL SLIP IN MONDAY AFTERNOON AND EVENING...WITH BETTER WARMING
AND GUSTY SOUTHWEST WINDS TUESDAY. THEN THE SLIGHT CHRISTMAS DAY
COOL-DOWN WITH SLOW WARMING THURSDAY AND FRIDAY. BIGGER BOOST IN
TEMPERATURES AND MORE GUSTY SOUTHWEST BREEZES EXPECTED SATURDAY
BEFORE NEXT COOLING THE FOLLOWING SUNDAY. MINOR CHANGES. RMCQUEEN
&&
.PRELIMINARY POINT TEMPS/POPS...
FRIONA 37 19 42 24 55 / 10 0 0 0 0
TULIA 38 20 42 24 56 / 10 0 0 0 0
PLAINVIEW 40 21 46 25 56 / 10 0 0 0 0
LEVELLAND 42 22 49 26 56 / 10 0 0 0 0
LUBBOCK 42 23 49 26 57 / 10 0 0 0 0
DENVER CITY 44 24 50 28 55 / 10 0 0 0 0
BROWNFIELD 44 24 51 27 56 / 10 0 0 0 0
CHILDRESS 40 22 46 24 57 / 10 0 0 0 0
SPUR 45 23 50 27 57 / 10 0 0 0 0
ASPERMONT 45 24 51 29 58 / 0 0 0 0 0
&&
.LUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
93
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
300 PM CST SUN DEC 22 2013
.SHORT TERM...(TONIGHT THROUGH MONDAY NIGHT)
ISSUED AT 300 PM CST SUN DEC 22 2013
MAIN FORECAST CONCERNS THIS PACKAGE...CONTINUING LIGHT SNOW
TONIGHT/MON...LOWS/WIND CHILLS MON NIGHT.
18Z DATA ANALYSIS HAD A BROAD AREA OF LOW PRESSURE NEAR LAKE ERIE
WITH TROUGHING NORTHWEST THRU LOWER MI/WI INTO NORTHERN MN. MAIN
SNOW AREA WITH THE SHORTWAVE THAT TRACKED NORTHEAST ACROSS NORTHERN
IL EARLY THIS MORNING WAS ALREADY EXITING NORTHEAST WI. WARNINGS/
ADVISORIES IN/AROUND THE AREA BEFORE 18Z DUE TO THE RAPID EXIT OF
THIS SNOW AREA.. LIGHT SNOW FALLING OVER WESTERN WI/MUCH OF MN AT
MID-DAY WAS ASSOCIATED WITH STRONG TROUGHING/SHORTWAVE ENERGY
DIGGING SOUTHEAST INTO THE UPPER MIDWEST. VISIBILITIES IN MUCH OF
THIS SNOW VARIED FROM 1 TO 7 MILES.
INITIALIZATIONS OF 22.12Z MODELS GENERALLY GOOD WITH SOLUTIONS VERY
SIMILAR FOR TONIGHT THRU MON NIGHT...THOUGH NO 22.12Z CAN-GEM DATA
AVAILABLE THIS CYCLE. THIS AS NORTHERN STREAM ENERGY CARVES OUT A
RATHER DEEP MID LEVEL TROUGH OVER THE UPPER MIDWEST TONIGHT/MON THEN
SHORTWAVE RIDGING BUILDS IN MON NIGHT. TREND CONTINUES TO FAVOR
STRONGER/SLOWER WITH THE TROUGH THRU THE PERIOD. CHECK OF OBS VS.
MODEL DATA AT 18Z SHOWED ALL TO BE QUITE REASONABLE WITH THE LK ERIE
SFC LOW AND TROUGHING BACK INTO MN/WI. BLEND OF THE MODELS LOOKED
BEST WITH THE 12-18Z PRECIP OVER THE CENTRAL/EASTERN CONUS THOUGH
INDIVIDUALLY ALL WERE VERY SIMILAR WITH THIS. PER WV IMAGERY ALL
LOOKED QUITE GOOD WITH THE SHORTWAVE DETAILS OVER NOAM. NO ONE
FAVORITE AND WITH SOLUTIONS TRENDING TOWARD AN EVEN TIGHTER
CONSENSUS...FAVORED THE MODEL/ENSEMBLE CONSENSUS. SHORT-TERM FCST
CONFIDENCE IS GOOD THIS CYCLE.
FOR THE SHORT TERM...ATTENTION IS FOCUSED ON THE UPSTREAM SHORTWAVE
ENERGY/SHORTWAVES OVER THE DAKOTAS TO SASKAT/ALB TO CARVE OUT A DEEP
MID LEVEL TROUGH OVER THE UPPER MIDWEST THE NEXT 24HRS. FALLING HGTS
AND DIVERGENCE ALOFT WITH PV ADVECTION AHEAD OF THE SHORTWAVES WORK
TO DEEPEN AN 850-700MB LOW/CIRCULATION OVER WESTERN WI/EASTERN MN
TONIGHT...TO DRIFT SOUTHEAST ACROSS THE AREA MON. THE INCREASING
LOWER LEVEL CYCLONIC CONVERGENCE WORKS WITH THE DIVERGENCE ALOFT TO
CONTINUE WRINGING OUT SOME OF THE PLENTIFUL SFC-700MB AND ABOVE
MOISTURE IN THE COLUMN. DEEPEST OF THE MOISTURE/STRONGER OF THE
CONVERGENCE/LIFT IS OVER THE NORTHEAST 3/4 OR SO OF THE FCST AREA
TONIGHT/MON AS THE WEAK 850-700MB LOW DEVELOPS/MOVES SOUTHEAST
ACROSS THE AREA. CONTINUED 70-100 PERCENT -SN CHANCES FOR THE
NORTHEAST 3/4 OF THE FCST AREA TONIGHT...THEN TREND THESE SLOWLY
EASTWARD AND DOWNWARD MONDAY AS THE 850-500MB TROUGH AXIS GRADUALLY
PASSES. GIVEN THE COOLING COLUMN AND THE DENDRITIC GROWTH ZONE ABOUT
HALF THE DEPTH OF THE SFC-700MB LAYER SNOW-WATER RATIOS LOOKING TO
BE MORE IN THE 15-20 TO 1 RANGE. MODEL CONSENSUS PRODUCES 0.05 TO
0.15 INCH OF QPF OVER THE NORTHEAST 2/3 OF THE FCST AREA TONIGHT...
THUS 1 TO 2 INCHES OF SNOWFALL EXPECTED ACROSS THAT PORTION OF THE
FCST AREA TONIGHT THRU EARLY MONDAY AFTERNOON.
COLDER AIR FILTERS IN TONIGHT WITH TEMPS REACHING NEAR OR JUST BELOW
ZERO ACROSS THE WEST END OF THE FCST AREA LATE TONIGHT. THIS WITH
NORTHWEST WINDS IN THE 10-15 MPH RANGE. WIND CHILLS AT SITES LIKE
KTOB/KAUM/KCCY DIP TO AROUND -20 LATE TONIGHT/MON MORNING. WILL
ISSUE A WIND CHILL ADVISORY FOR 06Z-18Z MON FOR THE WESTERN 6
COUNTIES OF THE FCST AREA.
RATHER SHARP SFC-850MB RIDGE AXIS BUILDS EAST INTO THE FCST AREA MON
NIGHT...TO NEAR THE MS RIVER BY 12Z TUE. HOWEVER MODEL CONSENSUS
RELUCTANT TO CLEAR OUT THE LOWER LEVEL MOISTURE OVER WI EAST OF THIS
RIDGE AXIS. WITH LIGHTER WINDS MON NIGHT...CLOUDS OR NO CLOUDS WILL
HAVE AS MUCH AS A 5F TO 10F IMPACT ON LOW TEMPS...WARMER UNDER THE
CLOUDS. GIVEN THE CLOUD UNCERTAINTIES STAYED WITH THE MODEL/ENSEMBLE
CONSENSUS FOR LOWS MON NIGHT...WITH LOWS IN THE -5F TO -15F RANGE.
THESE TEMPS COMBINED WITH EVEN THE LIGHTER NORTHWEST WINDS TO
PRODUCE WINDS CHILLS OF -20 TO -30 MON NIGHT INTO TUE MORNING. TO
AVOID THE /DOUBLE HEADLINE/ WILL HOLD OFF ON A WIND CHILL ADVISORY
FOR THIS TIME PERIOD FOR NOW.
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 300 PM CST SUN DEC 22 2013
MAIN FORECAST CONCERNS FOR THE TUE THRU WED NIGHT PERIOD ARE
LIGHT SNOW CHANCES/AMOUNTS LATE TUE THRU WED NIGHT.
TIGHTENING CONSENSUS AMONG THE 22.12Z MODELS CONTINUES IN THE TUE
THRU WED NIGHT PERIOD...ESPECIALLY TUE/TUE NIGHT AS THE SHORTWAVE
RIDGING QUICKLY PASSES AND THE NEXT STRONG NORTHWEST FLOW SHORTWAVE
DROPS INTO THE UPPER MIDWEST. SOME DIFFERENCES BY LATER WED/WED
NIGHT WITH GFS LOOKING TO BE A FAST OUTLIER WITH A SECONDARY
SHORTWAVE TO DROP INTO/ACROSS THE REGION. FCST CONFIDENCE REMAINS
QUITE GOOD TUE/TUE NIGHT...THEN AVERAGE FOR WED/WED NIGHT.
SFC-700MB RIDGE AXIS TRANSLATES QUICKLY ACROSS THE AREA TUE...WITH
RATHER STRONG 925-700MB WARM ADVECTION AND SFC-500MB MOISTURE
SPREADING QUICKLY ACROSS THE AREA. PV ADVECTION AHEAD OF THE LEAD
SHORTWAVE PLUS THE STRONG LOW LEVEL WARM ADVECTION/ISENTROPIC
LIFT PROVIDE RATHER DEEP UPWARD FORCING THRU THE COLUMN CENTERED
ON TUESDAY EVENING. DEEP DENDRITIC GROWTH ZONE INDICATED LATE TUE
AFTERNOON/NIGHT...FOR WHAT SHOULD BE RATHER FLUFFY CHRISTMAS EVE
SNOW. BASED ON MODEL CONSENSUS QPF PRODUCTION...1 TO 3 INCHES OF
SNOW LOOKS QUITE LIKELY FOR THE FCST AREA FROM LATE TUE AFTERNOON
INTO WED MORNING. IF NAM/ECMWF ARE MORE CORRECT WITH A RATHER
STRONG SECONDARY SHORTWAVE TO DROP ACROSS THE AREA...ANOTHER ROUND
OF LIFT MOVES BY TO SQUEEZE OUT MORE LIGHT SNOW LATER WED INTO WED
NIGHT. FOR NOW LEFT -SN CHANCES WED AFTERNOON/NIGHT IN THE 20-40
PERCENT RANGE. USED THE MODEL/ENSEMBLE BLEND FOR HIGHS/LOWS TUE
THRU WED NIGHT.
FOR THURSDAY THROUGH SUNDAY.../DAYS 4 TO 7/...
MEDIUM RANGE MODEL RUNS OF 22.00Z/22.12Z SHOW GOOD BETWEEN MODEL
AND RUN-TO-RUN AGREEMENT WITH THE LARGER SCALE FEATURES OF LONGWAVE
TROUGHING OVER THE EASTERN HALF OF NOAM THU/FRI...WITH NORTHWEST
FLOW ALOFT OVER THE UPPER MIDWEST. HOWEVER PLENTY OF DETAIL
DIFFERENCES WITH SMALL SCALE SHORTWAVES RIPPLING ACROSS THE REGION
THRU THIS FLOW. ACTUALLY GOOD AGREEMENT FOR HGTS OVER THE REGION TO
RISE A BIT SAT AS THE THU/FRI TROUGH PROGRESSES EAST AND STRONGER
TROUGHING DIGS INTO THE NORTHERN ROCKIES. ANY RISE OF HGTS/WEAK
RIDGING ALOFT OVER THE REGION LOOKS SHORT LIVED AS MODELS MAINTAIN
GOOD CONSENSUS FOR RENEWED TROUGHING TO DIG INTO THE NORTH-CENTRAL
CONUS SUNDAY. WITH THE BETTER BETWEEN MODEL CONSISTENCY THIS CYCLE
THE DAY 4-7 FCST CONFIDENCE IS ON THE PLUS SIDE OF AVERAGE.
SOME GFS/ECMWF CONSISTENCY FOR A STRONGER SHORTWAVE/TROUGH TO BE
ROTATING EAST OF THE FCST AREA AT 12Z THU. DRIER CAN HIGH PRESSURE
TO BUILD IN BEHIND IT FOR THU INTO FRI...FOR WHAT SHOULD BE A
BREAK FROM THE LIGHT SNOW CHANCES OF MUCH OF THE TONIGHT THRU WED
NIGHT PERIOD. THE HIGH MOVES QUICKLY SOUTHEAST OF THE REGION FRI
AS LOW PRESSURE TRACKS ACROSS SOUTHERN CAN. THU NIGHT SHAPING UP
TO BE A NIGHT OF SUB-ZERO LOWS ACROSS THE FCST AREA WITH THE SFC
RIDGE AXIS/LIGHT WINDS ACROSS THE THE AREA THAT NIGHT. MDT/STRONG
LOWER LEVEL WARM ADVECTION SPREADS ACROSS THE AREA FRI/FRI NIGHT.
APPEARS MUCH OF THIS GOES INTO WARMING...WITH SFC- 700MB MOISTURE
REMAINING SCANT AND LITTLE IN THE WAY OF UPWARD MOTION GENERATED.
850MB TEMPS PROGGED TO GO FROM AROUND -8C TO -12C AT 12Z FRI TO 0C
TO +6C BY 12Z SAT AS WESTERLY SFC-700MB FLOW BECOMES MORE WESTERLY
ACROSS THE REGION. WILL LEAVE FRI NIGHT/SAT DRY FOR NOW WITH THE
STRONG UPWARD TREND IN TEMPS FOR THE WEEKEND. GOOD GFS/ECMWF
CONSISTENCY FOR A STRONGER SFC THRU 700MB TROUGH TO SLIDE
SOUTHEAST ACROSS THE AREA SAT NIGHT INTO SUN. LOWER LEVEL COLD
ADVECTION AND AN INCREASE OF LOWER LEVEL MOISTURE TO FOLLOW THE
TROUGH AXIS. IF PRESENT TIMING/ CONSENSUS MAINTAINS...WHAT SMALL
MODEL CONSENSUS -SN CHANCES ARE IN THE FCST GRIDS FOR SAT
NIGHT/SUN WOULD HAVE TO BE RAISED. MODEL/ ENSEMBLE CONSENSUS FOR
THU THRU SUN HIGHS/LOWS APPEAR REASONABLE.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 1122 AM CST SUN DEC 22 2013
SOME UNCERTAINTY ON WHAT THE CEILINGS ARE GOING TO DO THROUGH THE
PERIOD. POCKET OF VFR CONDITIONS HAS DEVELOPED IN THE WAKE OF THE
SNOW BAND AND IS OVER BOTH TAF SITES. HOWEVER...OFF TO THE
NORTHWEST...LARGE AREA OF MVFR CEILINGS IN PLACE AHEAD OF THE NEXT
SHORT WAVE TROUGH THAT WAS ACROSS THE EASTERN DAKOTAS. EXPECT THAT
AS THE SHORT WAVE TROUGH MOVES IN THAT THE CEILINGS SHOULD GO DOWN
TO MVFR AND HAVE TRENDED THE FORECAST THAT WAY. FOR THE MOST
PART...EXPECT THE VISIBILITY TO REMAIN VFR DESPITE HAVING LIGHT SNOW
FALLING THROUGH THE ENTIRE FORECAST PERIOD. THE 22.16Z RAP INDICATES
THE BETTER CHANCES FOR VISIBILITY RESTRICTIONS IN THE LIGHT SNOW TO
EXTEND FROM ABOUT THE TWIN CITIES INTO CENTRAL WISCONSIN STAYING
NORTH OF BOTH TAF SITES.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
MN...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST MONDAY FOR
MNZ086-094.
IA...WIND CHILL ADVISORY FROM MIDNIGHT TONIGHT TO NOON CST MONDAY FOR
IAZ008-009-018-019.
&&
$$
SHORT TERM...RRS
LONG TERM....RRS
AVIATION.....04