AREA FORECAST DISCUSSION
NWS DENVER CO
315 PM MST TUE DEC 27 2011
SHORT TERM...A MODERATE NORTHWESTERLY FLOW ALOFT REMAINS IN PLACE
ACROSS THE CWFA TONIGHT. LATEST SATELLITE LOOPS INDICATE WEAK
SHORTWAVE OVER WYOMING WITH THE TAIL END EXTENDING INTO NORTHWEST
COLORADO. AT THIS TIME RADAR`S NOT SHOWING MUCH IN THE WAY OF PRECIP
AND SURFACE OBS NOT REPORTING ANY SNOWFALL. LATEST RUC AND NAM QG
VERTICAL VELOCITY PROGS SHOW SOME WEAK ASCENT IN THE MID LEVELS
ACROSS THE NORTHERN TIER OF COLORADO AS IT MOVES ACROSS THE AREA
THROUGH THE EARLY EVENING. MODEL CROSS SECTIONS THROUGH THE EVENING
SHOW SOME INCREASE IN MOISTURE ALONG WITH FAIRLY DECENT OROGRAPHICS.
STILL THINK THE COMBINATION OF ASCENT AND OROGRAPHICS WILL BE ENOUGH
TO GENERATE SOME LIGHT SNOW...THOUGH NO QPF/SNOW INDICATED VIA THE
MODELS. CROSS SECTIONS ALSO INDICATE AN INCREASE IN WINDS THROUGH 03Z
WITH A PEAK OF CROSS MOUNTAIN FLOW OF 50 KTS AROUND 00Z. THE GUSTY
WINDS SHOULD CREATE SOME BLOWING SNOW ACROSS THE MOUNTAINS AS WELL
AS IN AND NEAR THE FOOTHILLS...MAINLY OVER THE HIGHER PASSES WHERE
THERE IS DECENT SNOW COVER. WILL KEEP THE MENTION OF BLOWING SNOW IN
THE GRIDS THROUGH 03Z. THE BLOWING SNOW LOOKS TO BE LESS OF AN ISSUE
AND RATHER LOCALIZED FOR ZONE 39...BUT ENOUGH OF A THREAT TO KEEP IN
THE GRIDS. BASED ON MODEL CROSS SECTIONS...SHOULD SEE A DECREASE IN
WINDS AFTER 03Z AS CROSS MOUNTAIN FLOW DECREASES TO AROUND 35 KTS AT
MOUNTAIN TOP. DROPPED THE SLIGHT CHANCE OF MOUNTAIN SNOW AFTER
MIDNIGHT DUE TO THE LACK OF MOISTURE AND QG ASCENT. AS FOR THE PLAINS
DRY CONDITIONS TO PREVAIL TONIGHT WITH DECREASING WINDS NEAR THE
FOOTHILLS. ON WEDNESDAY...A MODERATE WEST TO NORTHWEST FLOW ALOFT
PREVAILS OVER THE CFWA. MODELS SHOW ANOTHER WEAK SHORTWAVE SLIDING
INTO IDAHO AND WESTERN WYOMING BY THE AFTERNOON. SOME INCREASE IN
MID LEVEL MOISTURE NOTED ON CROSS SECTIONS OVER THE MOUNTAINS AFTER
18Z ALONG WITH SOME FAVORABLE OROGRAPHICS...BUT LAPSE RATES LOOK LOW
AND QG VERTICAL PROGS INDICATING MINIMAL ASCENT. ANY SNOW CHANCES
FOR THE MOUNTAINS LOOK LOW...WILL KEEP THE SLIGHT CHANCE FOR ZONES
31 AND 33 DURING THE AFTERNOON. AS FOR PLAINS...DRY CONDITIONS TO
PREVAIL WITH SOME INCREASE IN HIGH LEVEL MOISTURE. NAM SHOWS SOME
SURFACE WINDS TO AROUND 25 KTS NEAR THE WYOMING BORDER DURING THE
AFTERNOON...OTHERWISE WINDS SHOULD BE FAIRLY LIGHT. TEMPERATURE AND
THICKNESS PROGS SUGGEST HIGHS AROUND 50 ACROSS THE PLAINS...WITH
LOWER 50S NEAR THE EASTERN BORDER ZONES. GUIDANCE TEMPERATURES SEEM
A BIT TOO WARM WILL UNDERCUT A BIT WHERE THERE REMAINS SNOW COVER.
.LONG TERM...A CHANCE OF SNOW WILL CONTINUE OVER MAINLY THE NORTHERN
MOUNTAINS WEDNESDAY NIGHT THEN SPREAD SOUTH OF INTERSTATE 70 DURING
THE DAY THURSDAY AS THE SHORTWAVE MOVES IN. AMOUNTS LOOK TO BE THE
GREATEST OVER THE MOUNTAINS NEAR STEAMBOAT WITH BETWEEN 4 TO 6
INCHES FALLING BETWEEN WEDNESDAY AFTERNOON THROUGH THURSDAY NIGHT.
AMOUNTS WILL BE LESS ELSEWHERE. ALSO WITH THE SHORTWAVE...WINDS OVER
THE EASTERN MOUNTAINS AND ALONG THE FOOTHILLS WILL BE INCREASING. A
DEEPENING SURFACE TROUGH OVER THE EASTERN PLAINS COMBINED WITH
DOWNWARD QG MOTION AND A 130 KT JET NEARBY WILL BRING DOWNSLOPING
GUSTS UP TO 65 MPH POSSIBLE OVER THE HIGHER TERRAIN EAST OF THE
DIVIDE...ESPECIALLY OVER LARIMER AND BOULDER COUNTIES. WILL HOLD OFF
ON ISSUING ANY HIGHLIGHTS...HOWEVER THE LATEST NAM MODEL THAT JUST
CAME IN IS PLACING THE JET CLOSER OVERHEAD WHICH WOULD ALLOW
STRONGER WINDS. WILL SEE IF OTHER MODELS FOLLOW SUIT. TEMPERATURES
ON THURSDAY WILL WARMER DUE TO THE DOWNSLOPING WARMING...SHOULD SEE
50S OVER THE PLAINS WITH READINGS NEAR 60 OVER THE FAR NORTHEASTERN
PLAINS. THE MINIMUM TEMPERATURES THAT NIGHT WILL ALSO REMAIN
WARM.
AN UPPER RIDGE WILL MOVE OVERHEAD ON FRIDAY TO KEEP IN THE WARM
TEMPERATURES AND DRY CONDITIONS. CLOSE ON ITS HEELS HOWEVER WILL BE
ANOTHER SHORTWAVE IN THE CONSTANT NORTHWEST FLOW ALOFT. THIS WILL
BRING ANOTHER ROUND OF SNOW TO THE NORTHERN MOUNTAINS AND WINDY
CONDITIONS SPREADING INTO THE FOOTHILLS...BUT WITH LIGHTER SPEEDS
THAN THURSDAY. THE CHANCE OF SNOW WILL LAST INTO SATURDAY BEFORE A
BIGGER UPPER RIDGE IS PROGGED TO MOVE OVER THE WESTERN STATES TO
BRING WARM AND DRY WEATHER TO NORTHEASTERN COLORADO THROUGH THE
WEEKEND AND INTO THE FIRST HALF OF NEXT WEEK...AND THE NEW YEAR.
&&
AVIATION...VFR CONDITIONS TO CONTINUE THROUGH WEDNESDAY WITH VARYING
AMOUNTS OF MAINLY HIGH LEVEL CLOUDS. SURFACE WINDS SHOULD WEAKEN
DURING THE EVENING AND BECOME SOUTHWEST BY 03Z AS DRAINAGE PATTERN
DEVELOPS. EXCEPTION WILL BE AT KBJC WHERE WESTERLY WINDS WILL
PREVAIL OVERNIGHT WITH SOME GUSTS TO 30 KTS THROUGH 06Z. ON
WEDNESDAY...SOUTHWEST SURFACE GRADIENT TO PREVAIL...WITH SPEEDS
AROUND 12KTS. SOME GUSTS TO 20 KTS POSSIBLE AT KBJC...MAINLY IN THE
MORNING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...D-L
LONG TERM....KRIEDERMAN
AVIATION...D-L
AREA FORECAST DISCUSSION
NWS ALBANY NY
114 PM EST TUE DEC 27 2011
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION
THIS AFTERNOON AND TONIGHT WITH WIDESPREAD PRECIPITATION AND
BREEZY CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT
AREAS WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW
ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY
WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR
RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO
EASTERN CANADA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS HAVE PRETTY MUCH SPREAD OVER THE ENTIRE AREA...AND AREA
RADARS SHOWING SOME VIRGA. NO PRECIPITATION IS REACHING THE GROUND
OVER THE REGION YET...BUT SHOULD DEVELOP OVERHEAD THROUGH THE
AFTERNOON. TEMPERATURES HAVE WARMED RAPIDLY...BUT WITH THE CLOUD
COVER AND EVENTUAL RAIN...TEMPERATURES SHOULD RISE ONLY A DEGREE
OR TWO MORE THROUGH THIS AFTERNOON. CURRENT OBSERVATIONS AND
TRENDS SUPPORT MOST OF THE CURRENT FORECAST THROUGH THIS
AFTERNOON...SO FEW CHANGES NEEDED IF ANY.
REV AFD BELOW...
AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE
SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR
W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND
A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A
NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL
UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM
DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250
JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS
SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE
H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE
S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE
THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE
THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS
OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE
POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z-
00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH
THE FCST AREA AS EARLY AS 03Z !
THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST
EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE
MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION
EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO
LOW CONFIDENCE AND A SMALL PROBABILITY.
FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS
INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO
RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE
IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN
THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT
THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE
2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON
OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR
PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER.
PREVIOUS NEAR TERM...
AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP
GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND
THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST
PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED
EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD.
****PREVIOUS DISCUSSION****
HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE
THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO
THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO
PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID
ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL
RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE
FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN
WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY
AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM
WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA.
A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF
THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A
MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY
THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN
WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4
INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND
NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE
PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY
ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE
CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS
LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER
ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE
LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN
HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW
DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST
HWOALY.
MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT
THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS
EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE
THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE
SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS
LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO
MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT
MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS
BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES.
TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE
DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW
MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY
TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY
MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE
NORTHWEST...AND 30S ELSEWHERE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS
ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY
OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR
TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND
SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER
AMOUNTS ELSEWHERE.
MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE
ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST
WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER
CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS
BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST
AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35
TO 45 MPH.
TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR
SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR
TWO HIGHER THAN THE LOWS WEDNESDAY MORNING.
WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT
LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A
DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO
30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT
WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO
THE UPPER TEENS OVER THE SOUTH.
A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON
THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY
NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE
THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING
IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10
ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW...
WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE
CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE
PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF
THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN
AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN
OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE
SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND
30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL
BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS
10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID
20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE
ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE
POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE
HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST.
HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH
PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT
AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER
AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND
20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES
ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED
BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE...
ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE
MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT
BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN
TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE
LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND
COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY
PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S
SOUTH.
&&
.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
LOW PRESSURE CONTINUES TO DEEPEN AND INTENSIFY NEAR THE PIEDMONT
REGION THIS AFTERNOON. THE CYCLONE WILL QUICKLY MOVE NORTHEAST
ACROSS CENTRAL NY THIS EVENING...AND INTO SOUTHEAST QUEBEC AFTER
MIDNIGHT.
VFR FLIGHT CONDITIONS WILL PERSIST PRIOR TO SUNSET...THEN
CONDITIONS WILL DETERIORATE BETWEEN 21Z TO 00Z WITH THE THERMAL
ADVECTION RAINFALL AHEAD OF THE INTENSIFYING CYCLONE. CONDITIONS
WILL LOWER TO MVFR VIS/CIG LEVELS...AND POTENTIALLY IFR LEVELS AT
KPOU PRIOR TO 00Z. THERE IS A MODERATE PROBABILITY THAT CONDITIONS
MAY DECREASE TO IFR LEVELS AT KALB AND KGFL BTWN 00Z-06Z/WED IN
THE PCPN SHIELD AHEAD OF THE WAVE. WE KEPT KALB AT LOW MVFR
LEVELS...AND LOWERED KGFL ALONG WITH KPOU TO IFR CONDITIONS IN
THAT TIME FRAME.
THE DRY SLOT TO THE SYSTEM MOVES INTO CNTRL-ERN NY AROUND MIDNIGHT.
THE PCPN WILL END AND CONDITIONS WILL RISE TO MVFR LEVELS AT ALL
THE SITES. CIGS WILL HANG AT HIGH MVFR AT KALB NORTH TO KGFL LATE
AND THE MORNING...WITH KPOU RISING TO LOW VFR CIGS LEVELS AFTER SUNRISE.
LOW LEVEL WIND SHEAR WILL BE AT LEAST A FACTOR AT KPOU BTWN 21Z-
04Z WITH THE 2 KFT AGL WINDS INCREASING TO 40-50 KTS. WE ADDED
LLWS GROUPS THERE. THE SFC WINDS WILL GENERALLY BE 10 KTS OR
LESS. FOR KALB AND KGFL...THE WINDS WILL BE FROM S/SE AT 8-15 KTS.
THE 2 KFT AGL WINDS ARE EXPECTED TO BE AROUND 30-35 KTS.
OVERALL THE WINDS WILL BACK FROM THE S/SE TO THE E/NE AT 5-10 KTS.
EARLY THIS EVENING. THEY WILL VEER TO THE SW AFTER MIDNIGHT AT
AROUND 10 KTS. THE WINDS WILL INCREASE FROM THE WEST AFTER 12Z AT
12-18 KTS WITH SOME GUSTS GREATER THAN 25 KTS /ESPECIALLY AT KALB
DUE TO FUNNELING DOWN THE MOHAWK RIVER VALLEY/ WITH THE LOW LEVEL
PRESSURE GRADIENT INCREASING BETWEEN THE DEPARTING STORM AND HIGH
PRESSURE BUILDING IN FROM THE LOWER MS RIVER VALLEY. ALSO...THE
BUFKIT MOMENTUM TRANSFER PROFILES INDICATED GUSTS GREATER THAN 30
KTS MAY BE NEEDED IN THE AFTERNOON.
OUTLOOK...
WED PM...MVFR IMPROVING TO VFR. WINDY
THU...VFR. NO SIG WX.
FRI...VFR/MVFR...CHC -SHSN/-SHRA.
SAT- SUN...VFR...SLIGHT CHC -SHSN/-SHRA.
&&
.HYDROLOGY...
WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH
TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED
TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN
WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY
AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON
REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD
HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND
STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY
ENOUGH TO BRING RIVERS UP TO FLOOD.
DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE.
A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE
LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM.
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...NAS
NEAR TERM...NAS
SHORT TERM...GJM
LONG TERM...RCK
AVIATION...WASULA
HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS ALBANY NY
1223 PM EST TUE DEC 27 2011
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION
THIS AFTERNOON AND TONIGHT WITH WIDESPREAD PRECIPITATION AND
BREEZY CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT
AREAS WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW
ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY
WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR
RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO
EASTERN CANADA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
CLOUDS HAVE PRETTY MUCH SPREAD OVER THE ENTIRE AREA...AND AREA
RADARS SHOWING SOME VIRGA. NO PRECIPITATION IS REACHING THE GROUND
OVER THE REGION YET...BUT SHOULD DEVELOP OVERHEAD THROUGH THE
AFTERNOON. TEMPERATURES HAVE WARMED RAPIDLY...BUT WITH THE CLOUD
COVER AND EVENTUAL RAIN...TEMPERATURES SHOULD RISE ONLY A DEGREE
OR TWO MORE THROUGH THIS AFTERNOON. CURRENT OBSERVATIONS AND
TRENDS SUPPORT MOST OF THE CURRENT FORECAST THROUGH THIS
AFTERNOON...SO FEW CHANGES NEEDED IF ANY.
REV AFD BELOW...
AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE
SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR
W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND
A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A
NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL
UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM
DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250
JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS
SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE
H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE
S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE
THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE
THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS
OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE
POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z-
00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH
THE FCST AREA AS EARLY AS 03Z !
THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST
EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE
MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION
EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO
LOW CONFIDENCE AND A SMALL PROBABILITY.
FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS
INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO
RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE
IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN
THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT
THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE
2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON
OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR
PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER.
PREVIOUS NEAR TERM...
AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP
GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND
THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST
PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED
EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD.
****PREVIOUS DISCUSSION****
HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE
THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO
THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO
PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID
ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL
RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE
FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN
WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY
AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM
WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA.
A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF
THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A
MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY
THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN
WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4
INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND
NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE
PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY
ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE
CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS
LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER
ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE
LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN
HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW
DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST
HWOALY.
MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT
THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS
EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE
THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE
SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS
LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO
MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT
MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS
BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES.
TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE
DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW
MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY
TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY
MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE
NORTHWEST...AND 30S ELSEWHERE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS
ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY
OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR
TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND
SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER
AMOUNTS ELSEWHERE.
MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE
ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST
WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER
CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS
BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST
AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35
TO 45 MPH.
TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR
SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR
TWO HIGHER THAN THE LOWS WEDNESDAY MORNING.
WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT
LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A
DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO
30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT
WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO
THE UPPER TEENS OVER THE SOUTH.
A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON
THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY
NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE
THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING
IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10
ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW...
WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE
CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE
PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF
THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN
AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN
OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE
SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND
30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL
BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS
10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID
20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE
ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE
POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE
HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST.
HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH
PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT
AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER
AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND
20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES
ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED
BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE...
ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE
MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT
BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN
TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE
LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND
COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY
PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S
SOUTH.
&&
.AVIATION /17Z TUESDAY THROUGH SATURDAY/...
VFR FLIGHT CONDITIONS AND NO AVIATION WEATHER PROBLEMS ARE
EXPECTED THROUGH MID TO LATE AFTERNOON. SCATTERED HIGH CLOUDS
WILL THICKEN SOME AND LOWER DURING THE MORNING HOURS...WITH AN
ALTOSTRATUS DECK AROUND 15000 FT ASL BY MID TO LATE MORNING.
WINDS THIS MORNING WILL BE SOUTH 5 TO 10 KNOTS THIS MORNING
AND MOST OF THE AFTERNOON.
AS A LOW CENTER MOVES FROM THE OHIO VALLEY INTO THE MID ATLANTIC
REGION THIS AFTERNOON...CONDITIONS WILL DETERIORATE LATER THIS
AFTERNOON...WITH MVFR CONDITIONS AT BEST FOR THE EVENING HOURS AS
RAIN OVERSPREADS THE REGION. THE CEILING AND VISIBLITY ARE LIKELY
TO LOWER TO IFR DURING THE LATE EVENING HOURS AS THE BOUNDARY LAYER
BECOMES MOISTER...WITH WINDS BECOMING SOUTHEAST DURING THE LATE
AFTERNOON AND EARLY EVENING. WIDESPREAD IFR MAY BE EXPECTED DURING
THE NIGHTTIME HOURS DUE TO LOW CEILINGS AND POOR VISIBILITY.
SOME IMPROVEMENT TO MVFR MAY TAKE PLACE LATER TONIGHT AS THE STORM
LIFTS NORTH INTO CANADA.
LLWS MAY BECOME A FACTOR LATE THIS AFTERNOON AND EVENING AS WINDS
2000 TO 3000 FT AGL INCREASE TO 40-55 KTS.
OUTLOOK...
WED...MVFR...RAIN MIXING WITH SNOW AND TAPERING OFF TO SHWRS. WINDY.
THU...VFR. NO SIG WX.
FRI...VFR/MVFR...CHC -SHSN/-SHRA.
&&
.HYDROLOGY...
WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH
TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED
TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN
WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY
AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON
REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD
HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND
STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY
ENOUGH TO BRING RIVERS UP TO FLOOD.
DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE.
A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE
LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM.
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...NAS
NEAR TERM...NAS
AREA FORECAST DISCUSSION
NWS ALBANY NY
1014 AM EST TUE DEC 27 2011
.SYNOPSIS...
AN AREA OF LOW PRESSURE WILL TRACK NORTHEAST ACROSS OUR REGION LATE
TODAY AND TONIGHT WITH WIDESPREAD PRECIPITATION AND BREEZY
CONDITIONS. MAINLY RAIN IS EXPECTED FROM THIS SYSTEM...BUT AREAS
WELL NORTH AND WEST OF ALBANY WILL GET SOME LIGHT SNOW
ACCUMULATIONS...ESPECIALLY TONIGHT...AS RAIN CHANGES TO SNOW. VERY
WINDY AND COLDER CONDITIONS WITH SCATTERED TO NUMEROUS SNOW AND OR
RAIN SHOWERS WILL OCCUR WEDNESDAY...AS THE STORM MOVES INTO EASTERN
CANADA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 950 AM EDT...LOW PRESSURE CONTINUES TO RAPIDLY FORM NEAR THE
SRN APPALACHIANS THIS HOUR. THE BEST MSAS PRESSURE FALLS ARE NEAR
W-CNTRL NC. THE WATER VAPOR LOOP HAS A SHORT-WAVE ROTATING AROUND
A STRONG SOUTHERN STREAM NEGATIVELY TILTED UPPER TROUGH. A
NORTHERN STREAM DISTURBANCE IS ALSO TRYING TO PHASE IN. A DUAL
UPPER LEVEL JET STREAK STRUCTURE IS IN PLACE WITH THE STORM
DEEPENING AND INTENSIFYING ALONG THE LEFT FROM QUADRANT OF A H250
JET STREAK OF 100+ KTS...AND A 140+ KT JET STREAM IS MOVING ACROSS
SRN QUEBEC. THE LOW LEVEL JET WILL INCREASE AHEAD OF THE WAVE. THE
H850 WINDS INCREASE TO 45-60 KTS BTWN 18Z-00Z. WE INCREASED THE
S/SE WINDS TO 10 TO 20 MPH WITH SOME GUSTS IN THE 30-40 MPH LATE
THIS PM AND EARLY THIS EVENING. THE STRONGEST WINDS LOOK LIKE
THESE WILL BE ALONG THE SRN GREENS...ERN CATSKILLS...AND PORTIONS
OF THE MOHAWK VALLEY INTO THE SRN DACKS. WE SLIGHTLY RETOOLED THE
POPS BASED ON THE LATEST HRRR AND NAM12 WITH AN ONSET IN THE 21Z-
00Z TIME FRAME. THIS WAVE IS A FAST MOVER. THE DRY SLOT MAY REACH
THE FCST AREA AS EARLY AS 03Z !
THE NAM SHOWS SOME ELEVATED INSTABILITY GRAZING THE SOUTHEAST
EXTREME OF THE FCST AREA WITH SHOWALTER VALUES OF 0 TO -1C. THERE
MAYBE A RUMBLE OF THUNDER SOUTH AND EAST OF THE CAPITAL REGION
EARLY THIS EVENING. WE DID NOT ADD THUNDER TO THE GRIDS YET DUE TO
LOW CONFIDENCE AND A SMALL PROBABILITY.
FINALLY...A LOOK AT THE CRITICAL THICKNESSES AND MODEL SOUNDINGS
INDICATE MAINLY A RAIN PTYPE WITH SOME SNOW TRANSITIONING TO
RAIN...THEN BACK TO SNOW OVER THE SRN AND WRN ADIRONDACKS. THERE
IS A VERY SMALL CHC OF A BRIEF PERIOD OF SOME POCKETS OF -FZRA IN
THE SRN DACKS...BUT WE WERE NOT CONFIDENT TO ADD THIS PTYPE AT
THIS TIME. TOTAL SNOWFALL AMOUNTS IN THE SRN DACKS WILL BE IN THE
2 TO 5 INCH RANGE. T/TD/RH/APPARENT TEMPS WERE REDONE BASED ON
OBSERVATIONS...AND CLOUDS WERE RETOOLED BASED ON THE VIS/IR
PICTURE...AS MID AND HIGH CLOUDS CONTINUES TO THICKEN AND LOWER.
PREVIOUS NEAR TERM...
AS OF 600 AM...HAVE MADE SOME ADJUSTMENTS TO THE HOURLY TEMP
GRIDS...WITH LITTLE ELSE CHANGED. 06Z NAM/GFS ARE NOW IN...AND
THEY CONTINUE TO SHOW A STORM TRACK THAT IS OVER THE NORTHWEST
PART OF THE FORECAST AREA...SO WARM MOSTLY RAIN SOLUTION USED
EARLIER TO PRODUCE THE FORECAST STILL LOOKS GOOD.
****PREVIOUS DISCUSSION****
HAVE WORKED THE PAST FEW NIGHTS AND HAVE SEEN THE MODELS CONTINUE
THEIR TREND OF TRACKING THE UPCOMING STORM FURTHER AND FURTHER TO
THE WEST. THE CURRENT 00Z RUNS ARE ALL NOW FORECASTING THE LOW TO
PASS TO THE NORTH AND WEST OF ALBANY. WITH NO RETREATING FRIGID
ARCTIC AIR MASS IN PLACE OVER THE REGION...THE WARMING THAT WILL
RESULT FROM SUCH A TRACK WILL PRODUCE MOSTLY RAIN ACROSS THE
FORECAST AREA...EVEN THE ADIRONDACK PART OF THE FORECAST AREA. RAIN
WILL BEGIN TO SPREAD INTO THE FORECAST AREA FROM THE SOUTHWEST BY
AROUND 200 PM...AND SPREAD SO RAPIDLY NORTHEAST THAT BY 5 OR 6 PM
WIDESPREAD RAINFALL WILL BE FALLING ACROSS THE ENTIRE FORECAST AREA.
A MIX OF SNOW AND RAIN IS POSSIBLE OVER THE FAR NORTHWEST PART OF
THE FORECAST AREA...WHICH MAY CONTINUE THROUGH THE EVENING AS A
MIX...THEN CHANGE TO ALL SNOW THERE AROUND OF AFTER 06Z TONIGHT. BY
THE TIME THE CHANGEOVER TO ALL SNOW BEGINS...THE BULK OF THE PCPN
WILL HAVE ALREADY PASSED...SO AM EXPECTING NO MORE THAN 1 TO 4
INCHES OF SNOW ACROSS HERKIMER... HAMILTON...NORTHERN FULTON AND
NORTHERN WARREN COUNTIES. ELSEWHERE...RAIN MAY CHANGE TO SNOW BEFORE
PCPN ENDS AS WELL...BUT IT WILL OCCUR SO LATE THAT LITTLE IF ANY
ACCUMULATION IS EXPECTED. AN INCH OR LESS HAS BEEN FORECAST IN THE
CENTRAL MOHAWK VALLEY...THE SCHOHARIE VALLEY AND EASTERN CATSKILLS
LATE TONIGHT...WITH LITTLE OR NO SNOW ELSEWHERE. NO WINTER WEATHER
ADVISORIES HAVE BEEN ISSUED AT THIS TIME SINCE SNOWFALL AMOUNTS ARE
LESS THAN THE ADVISORY CRITERIA. HOWEVER...SINCE WE HAVE BEEN
HIGHLIGHTING THIS EVENT IN THE HWOALY PRODUCT FOR THE PAST FEW
DAYS...CONTINUED TO MENTION THE SNOW ACCUMULATIONS IN THE LATEST
HWOALY.
MODEL WIND FORECASTS AT 925 MB AND 850 INDICATE SOUTHERLY WINDS AT
THOSE LEVELS WILL INCREASE TO 40 TO 50 KTS LATE TODAY AND THIS
EVENING. HOWEVER...MOS WIND FORECASTS AND MODEL SOUNDINGS INDICATE
THAT THESE STRONG WINDS ARE NOT LIKELY TO TRANSLATE DOWN TO THE
SURFACE DUE TO THE RAIN/PCPN INDUCED LOW LEVEL INVERSION THAT IS
LIKELY TO DEVELOP AFTER THE PCPN BEGINS. DAY SHIFT WILL NEED TO
MONITOR FOR THE POSSIBILITY THAT THE STRONG SOUTHERLY WINDS ALOFT
MAY MIX DOWN TO THE SURFACE...ESPECIALLY IF ANY CONVECTIVE ELEMENTS
BEGIN TO DEVELOP LATER TODAY AS THE PCPN APPROACHES.
TEMPS TODAY WILL RISE INTO THE UPPER 30S AND 40S BY LATE IN THE
DAY...AND GENERALLY REMAIN AT THOSE LEVELS UNTIL THE SURFACE LOW
MOVES BY AND WESTERLY WINDS BRING COLDER AIR IN. THIS IS NOT LIKELY
TO HAPPEN UNTIL AROUND OR AFTER 06Z TONIGHT. BY SUNRISE WEDNESDAY
MORNING...TEMPS WILL EVENTUALLY DROP INTO THE 20S OVER THE
NORTHWEST...AND 30S ELSEWHERE.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
TYPICAL BLUSTERY CONDITIONS WITH SCATTERED TO NUMEROUS SNOW SHOWERS
ACROSS THE REGION ON WEDNESDAY IN THE WAKE OF THE STORM...ESPECIALLY
OVER HIGHER TERRAIN AND DOWNWIND OF LAKE ONTARIO. ANOTHER INCH OR
TWO OF SNOW IS POSSIBLE FROM THE ADIRONDACKS TO THE MOHAWK AND
SCHOHARIE VALLEYS AND EASTERN CATSKILLS ON WEDNESDAY...WITH LESSER
AMOUNTS ELSEWHERE.
MODELS CONTINUE TO SHOW 925 AND 850 WINDS IN THE 40 TO 50 KT RANGE
ON WEDNESDAY...BUT WITH THE MIXING OF THE NOW WEST TO NORTHWEST
WINDS DOWN TO THE SURFACE MUCH MORE LIKELY...THERE IS A BETTER
CHANCE THAT A WIND ADVISORY MAY BE NEEDED ON WEDNESDAY...AND IT HAS
BEEN HIGHLIGHTED IN THE HWOALY PRODUCT ACROSS THE ENTIRE FORECAST
AREA. HAVE CURRENTLY FORECAST WINDS OF 15 TO 30 MPH WITH GUSTS OF 35
TO 45 MPH.
TEMPS WEDNESDAY MAY ACTUALLY FALL OR REMAIN STEADY AS COLDER AIR
SURGES IN. HAVE INDICATED HIGHS ON WEDNESDAY ONLY ABOUT A DEGREE OR
TWO HIGHER THAN THE LOWS WEDNESDAY MORNING.
WINDS AND SNOW SHOWERS WILL DIMINISH WEDNESDAY EVENING. EXPECT
LEFTOVER SNOW SHOWERS TO COMPLETELY END DURING THE EVENING...BUT A
DECENT WIND WILL CONTINUE THROUGH THE NIGHT WITH WIND GUSTS OF 25 TO
30 MPH POSSIBLE THROUGH WELL AFTER MIDNIGHT. LOWS WEDNESDAY NIGHT
WILL RANGE FROM A FEW DEGREES BELOW ZERO OVER THE ADIRONDACKS...TO
THE UPPER TEENS OVER THE SOUTH.
A CLIPPER LIKE SYSTEM WILL MOVE THROUGH THE GREAT LAKES ON
THURSDAY...BUT IT IS NOT LIKELY TO ARRIVE IN OUR AREA UNTIL THURSDAY
NIGHT. SO HAVE KEPT THE FORECAST FOR THURSDAY DRY...BUT DID INCREASE
THE CLOUD COVER. HIGHS THURSDAY WILL BE IN THE 20S TO MID 30S.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
A CLIPPER TYPE LOW APPROACHES THE REGION THURSDAY NIGHT RESULTING
IN CLOUDY SKIES...LOW CHANCE POPS...AND LOW TEMPS FROM AROUND 10
ABOVE NORTH TO THE UPPER 20S SOUTH. PRECIP AMOUNTS...ALL SNOW...
WILL BE VERY LIGHT AS THE THE SYSTEM IS MOISTURE STARVED. THE
CLIPPER MOVES ACROSS THE REGION ON FRIDAY. THE GFS IS MORE
PROGRESSIVE THAN THE ECMWF WHICH SLOWS DOWN THE MOVEMENT OF
THE CLIPPER AND MOVES IT FARTHER SOUTH. WARMER AIR IS DRAWN IN
AHEAD OF THE CLIPPER WHICH CHANGES THE PRECIP FROM SNOW TO RAIN
OVER MUCH OF THE REGION AND INCREASES THE PRECIP AMOUNTS TO THE
SOUTH OF THE RAIN SNOW LINE. HIGHS FRIDAY WILL RANGE FROM AROUND
30 NORTH TO THE LOW 40S SOUTH. THE PASSAGE OF THE CLIPPER WILL
BE FOLLOWED BY A SURGE OF COLD AIR WITH 850 TEMPS AROUND MINUS
10 WITH LOWS FRIDAY NIGHT FROM THE HIGH SINGLES NORTH TO THE MID
20S SOUTH. WESTERLY WINDS WILL RESULT IN A CHANCE FOR SOME LAKE
ENHANCED PRECIP WITH THE COLD ADVECTION WEST...ENOUGH FOR CHANCE
POPS DOWN THE MOHAWK VALLEY AND ELEVATED TERRAIN WEST OF THE
HUDSON VALLEY...WITH ONLY SLIGHT CHANCE POPS FARTHER EAST.
HIGHS SATURDAY WILL RANGE FROM THE MID 20S TO AROUND 40. HIGH
PRESSURE BRIEFLY CROSSES THE REGION SATURDAY INTO SATURDAY NIGHT
AND WINDS BACK AROUND TO A SOUTHWESTERLY DIRECTION BRINGING WARMER
AIR INTO THE REGION. LOWS SATURDAY NIGHT WILL RANGE FROM AROUND
20 NORTH TO 30 SOUTH. THE NEXT IN A SERIES OF CLIPPERS MOVES
ACROSS CANADA NORTH OF THE REGION ON SUNDAY...BRINGING A MIXED
BAG OF RAIN AND SNOW SHOWERS DEPENDING ON THE LATITUDE...
ELEVATION...AND TIME OF DAY. HIGHS SUNDAY WILL RANGE FROM THE
MID 30S NORTH TO THE LOWER 40S SOUTH. AS THE LOW MOVES EAST IT
BRINGS ANOTHER BLAST OF COLD IN ITS WAKE...CHANGING THE RAIN
TO SNOW SUNDAY EVENING. LOWS SUNDAY NIGHT WILL RANGE FROM THE
LOWER TEENS TO THE MID 20S. MONDAY LOOKS TO BE BLUSTERY AND
COLD WITH BRISK NORTHWEST WINDS 15 TO 25 MPH DURING THE MIDDAY
PERIOD AND HIGHS ONLY FROM AROUND 20 NORTH TO THE UPPER 30S
SOUTH.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
VFR FLIGHT CONDITIONS AND NO AVIATION WEATHER PROBLEMS ARE
EXPECTED THROUGH MID TO LATE AFTERNOON. SCATTERED HIGH CLOUDS
WILL THICKEN SOME AND LOWER DURING THE MORNING HOURS...WITH AN
ALTOSTRATUS DECK AROUND 15000 FT ASL BY MID TO LATE MORNING.
WINDS THIS MORNING WILL BE SOUTH 5 TO 10 KNOTS THIS MORNING
AND MOST OF THE AFTERNOON.
AS A LOW CENTER MOVES FROM THE OHIO VALLEY INTO THE MID ATLANTIC
REGION THIS AFTERNOON...CONDITIONS WILL DETERIORATE LATER THIS
AFTERNOON...WITH MVFR CONDITIONS AT BEST FOR THE EVENING HOURS AS
RAIN OVERSPREADS THE REGION. THE CEILING AND VISIBLITY ARE LIKELY
TO LOWER TO IFR DURING THE LATE EVENING HOURS AS THE BOUNDARY LAYER
BECOMES MOISTER...WITH WINDS BECOMING SOUTHEAST DURING THE LATE
AFTERNOON AND EARLY EVENING. WIDESPREAD IFR MAY BE EXPECTED DURING
THE NIGHTTIME HOURS DUE TO LOW CEILINGS AND POOR VISIBILITY.
SOME IMPROVEMENT TO MVFR MAY TAKE PLACE LATER TONIGHT AS THE STORM
LIFTS NORTH INTO CANADA.
LLWS MAY BECOME A FACTOR LATE THIS AFTERNOON AND EVENING AS WINDS
2000 TO 3000 FT AGL INCREASE TO 40-55 KTS.
OUTLOOK...
WED...MVFR...RAIN MIXING WITH SNOW AND TAPERING OFF TO SHWRS. WINDY.
THU...VFR. NO SIG WX.
FRI...VFR/MVFR...CHC -SHSN/-SHRA.
&&
.HYDROLOGY...
WHILE A SOAKING RAIN OF UP TO AROUND AN INCH IS EXPECTED THROUGH
TONIGHT...IT IS NOT EXPECTED TO RESULT IN FLOODING. RAIN IS EXPECTED
TO START LATE THIS AFTERNOON AND CONTINUE THROUGH TONIGHT. THE RAIN
WILL MIX WITH AND CHANGE TO SNOW WELL NORTH AND WEST OF THE ALBANY
AREA. HEAVIEST RAINFALL AMOUNTS ARE EXPECTED IN THE MID HUDSON
REGION OF NEW YORK AND OVER THE HOUSATONIC VALLEY AND LITCHFIELD
HILLS OF CONNECTICUT. MODEST RISES MAY BE EXPECTED ON THE RIVERS AND
STREAMS IN THIS AREA...BUT THE RAIN IS NOT EXPECTED TO BE HEAVY
ENOUGH TO BRING RIVERS UP TO FLOOD.
DRY WEATHER ON THURSDAY WILL ALLOW RIVERS AND STREAMS TO RECEDE.
A SERIES OF CLIPPER TYPE LOWS OVER THE NEW YEARS WEEKEND WILL HAVE
LITTLE EFFECT ON THE RIVERS SINCE MOISTURE WILL BE LACKING WITH THEM.
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...GJM/WASULA
NEAR TERM...GJM/WASULA
SHORT TERM...GJM
LONG TERM...RCK
AVIATION...RCK
HYDROLOGY...RCK
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
706 AM EST TUE DEC 27 2011
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM WILL LIFT THROUGH THE SE THIS MORNING
AND INTO THE CENTRAL APPALACHIANS AND VIRGINIA THIS AFTERNOON. A
STRONG COLD FRONT TRAILING FROM THE LOW WILL PASS THROUGH LATE THIS
MORNING AND THIS AFTERNOON. THE FRONT WILL BE PRECEDED BY WIDESPREAD
SHOWERS AND A FEW STRONGER THUNDERSTORMS...RESULTING IN SOME MUCH
NEEDED RAINFALL AND THE POSSIBILITY OF ISOLATED SEVERE WEATHER. HIGH
PRESSURE WILL THEN BUILD INTO THE AREA TONIGHT THROUGH THURSDAY. A
DRY COLD FRONT MAY MOVE IN LATE FRIDAY...BEFORE HIGH PRESSURE
RETURNS FOR SATURDAY. ANOTHER COLD FRONT MAY AFFECT THE AREA EARLY
NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A VERY ACTIVE NEAR TERM PERIOD IS ON TAP FOR TODAY WITH MULTIPLE
HAZARDS EXPECTED TO AFFECT SOUTHERN SC/SOUTHEAST GA AND THE ADJACENT
COASTAL WATERS. OVERALL...THERE ARE NO SIGNIFICANT CHANGES TO THE
GENERAL THINKING ABOUT THE UPCOMING EVENT. THE MAIN CHANGES ARE FOR
THE TIMING OF THE PRECIP THROUGH THE FORECAST AREA AND FOR UPDATES
TO EXPECTED WINDS. AS HAS BEEN WELL DOCUMENTED IN PRECEDING
FORECASTS...STRONG SYNOPTIC SCALE FORCING WILL MOVE ACROSS THE
REGION TODAY. A POTENT CLOSED UPPER LOW OVER THE LOWER MS VALLEY
WILL CONTINUE TO OPEN UP AND PHASE WITH NORTHERN STREAM ENERGY
DIVING ACROSS THE UPPER MIDWEST. DIVERGENCE ALOFT ASSOCIATED WITH A
120 KT JET COMBINED WITH STRONG LOW LEVEL LINEAR FORCING ALONG A
COLD FRONT WILL IS EXPECTED TO PUSH A BAND OF SHOWERS AND PERHAPS
EMBEDDED THUNDERSTORMS ACROSS THE REGION. NOW LETS TAKE A LOOK AT A
FEW ASPECTS OF THE EVENT.
TIMING OF PRECIP...RECENT OPERATIONAL MODEL RUNS HAVE GREATLY SPED
UP THE ARRIVAL OF THE APPROACHING SYSTEM. REGIONAL SATELLITE IMAGERY
SHOWS ONGOING PRECIP SURROUNDING THE FORECAST AREA TO THE NW AND W
WITH THE MAIN EVENTUAL CONVECTIVE LINE STARTING TO TAKE SHAPE OVER
THE NE GULF AND FL PANHANDLE. THE 05Z HRRR SEEMS TO HAVE THE BEST
HANDLE ON THE CURRENT PRECIP COVERAGE AND EVOLUTION AND THE POP
TREND FOR TODAY GENERALLY FOLLOWS IT. THE PRE FRONTAL LINE OF
SHOWERS/CONVECTION WILL BEGIN PUSHING INTO THE FAR WESTERN PORTION
OF THE FORECAST AROUND AROUND 12Z. I THEN TAKE THE AREA OF 100 POP
AND MARCH IT EASTWARD WITH THE BAND ENTERING THE CHARLESTON AREA IN
THE 14-15Z TIME FRAME. THE LINE OF SHOWERS AND/OR THUNDERSTORMS WILL
BE PUSHING OFFSHORE BY THE LATE MORNING WITH JUST LINGERING SHOWERS
INTO THE EARLY AFTERNOON FOR MOST OF THE AREA.
SEVERE WEATHER POTENTIAL...THE DEEP LAYER WIND FIELDS ASSOCIATED
WITH THIS SYSTEM CONTINUE TO LOOK QUITE IMPRESSIVE AND A HIGH
SHEAR/LOW CAPE ENVIRONMENT IS ANTICIPATED. A POWERFUL 850 MB
JET...ON THE ORDER OF 50-60 KTS...WILL TRAVERSE THE AREA THROUGH THE
LATE MORNING RESULTING IN 0-3 KM WIND SHEAR OF 50 KTS OR MORE
THROUGH THE LATE MORNING HOURS. SHEAR IS NOT THE PROBLEM WITH THIS
SYSTEM AND THE LIMITING FACTOR FOR SEVERE WEATHER WILL BE
INSTABILITY. GIVEN THAT THE SYSTEM IS EXPECTED TO MOVE THROUGH
EARLIER IN THE DAY THAN WITH PREVIOUS FORECASTS...THE TIME WINDOW
FOR DESTABILIZATION IS QUITE SHORT. IN FACT...WITH ONGOING PRECIP
AND DENSE CLOUD COVER...IT WILL BE DIFFICULT TO GET MUCH IN THE WAY
OF SURFACE BASED INSTABILITY. MODELS DO HINT AT A TIME IN THE LATE
MORNING WHERE INSTABILITY COULD DEVELOP AND PRIMARILY OVER THE TRI
COUNTY AREA AND ALONG THE IMMEDIATE COAST. GIVEN THE STRONGLY
SHEARED AND WEAKLY UNSTABLE ENVIRONMENT IN THE PRESENCE OF STRONG
LINEAR FORCING...THE PRIMARY CONVECTIVE MODE WOULD BE LINE SEGMENTS
CAPABLE OF PRODUCING DAMAGING WIND GUSTS. IN THE EVENT THAT THERE IS
ENOUGH INSTABILITY...THERE COULD BE A BRIEF ISOLATED BROKEN S TYPE
TORNADO. THE MAIN TIME PERIOD FOR POTENTIAL SEVERE WEATHER LOOKS TO
BE BETWEEN 9AM AND 1PM.
GUSTY WINDS...AS THE STRENGTHENING LOW LEVEL JET MOVES THROUGH THE
AREA STRONG GUSTY WINDS WILL DEVELOP ACROSS PORTIONS OF THE AREA. I
HAVE HOISTED A WIND ADVISORY WHICH INCLUDES THE TRI COUNTY AREA AND
BEAUFORT/COASTAL COLLETON COUNTIES. MIXING (ALBEIT LIMITED) WILL
BEGIN AROUND 13Z JUST AHEAD OF THE APPROACHING PRECIP BAND. AS IT
DOES YOU ONLY HAVE TO GO UP TO 500-1000 FEET TO REACH WINDS IN THE
35-40 KT RANGE BASED ON MODEL SOUNDINGS. WIND GUSTS OF 40-45 MPH
WILL BE POSSIBLE IN THE AFOREMENTIONED AREAS AND WILL EXTEND THE
ADVISORY THROUGH THE LATE AFTERNOON AS WINDS WILL REMAIN ELEVATED IN
THE SW TO W FLOW ONCE THE PRECIP BAND PASSES THROUGH.
TEMPERATURES WILL CONTINUE TO RISE THIS MORNING AS A WARM FRONT
PASSES THROUGH DURING THE NEXT FEW HOURS. UPPER 60S CAN BE EXPECTED
RIGHT ALONG THE COAST FROM SAVANNAH TO CHARLESTON WITH LOW TO MID
60S FURTHER INLAND.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
TONIGHT...DEEP LOW PRESSURE OVER THE NE CONTINUES TO STRENGTHEN AS
IT MOVES INTO SE CANADA OVERNIGHT. THE TRAILING COLD FRONT WILL HAVE
SHIFTED INTO THE ATLANTIC BY NIGHTFALL OFF OUR COASTS...AND HIGH
PRESSURE WILL STEADILY BUILD FROM THE WEST THROUGH THE NIGHT. STRONG
COLD ADVECTION EARLY WILL SLACKEN OFF AFTER MIDNIGHT...KEEPING
BREEZY CONDITIONS GOING UNTIL LATE EVENING OR THE OVERNIGHT HOURS.
AS SKIES CLEAR OUT...TEMPS WILL DROP STEADILY...BOTTOMING OUT
BETWEEN 35 AND 40 DEGREES MOST LOCALES.
LAKE WINDS...ONCE THE WIND ADVISORY COMES DOWN FOR BERKELEY COUNTY
IT WILL NEED TO BE REPLACED BY A WIND ADVISORY ON LAKE MOULTRIE
TONIGHT...AS COLD ADVECTION MOVING ACROSS THE WARMER LAKE WATERS
WILL ALLOW FOR GOOD MIXING OF 20-30 KT WITHIN THE BOUNDARY LAYER.
WEDNESDAY...A DRY WEST TO NW FLOW PREVAILS ALOFT...AS HIGH PRESSURE
AT THE SURFACE MOVES IN FROM THE WEST. WEAK COLD ADVECTION IN THE
MORNING WILL BE OFFSET BY DOWNSLOPE FLOW OFF THE MOUNTAINS AND
PLENTY OF SUNSHINE...BUT WITH 850 MB TEMPS ONLY AROUND 2-3C NORTH
AND 4-5C SOUTH...WE LOOK FOR MAX TEMPS MAINLY IN THE UPPER 50S.
WEDNESDAY NIGHT IS THEN THE COLDEST NIGHT OF THE FORECAST
PERIOD...AS THE HIGH SHIFTS CLOSER TO THE AREA AND GEOSTROPHIC WINDS
FALL TO UNDER 10 KT. THIS ALLOWS FOR EXCELLENT RADIATIONAL COOLING
AND WILL RESULT IN MIN TEMPS 30-35 INLAND FROM US-17...AND CLOSER TO
40 NEAR THE COAST.
THURSDAY...HIGH PRESSURE SLIPS A LITTLE SOUTH AS A CLIPPER TYPE LOW
PRESSURE SYSTEM MOVES THROUGH THE GREAT LAKES REGION. AFTER THE
CHILLY START...ABUNDANT SUNSHINE AND DOWNSLOPE FLOW OFF THE
APPALACHIANS WILL ALLOW FOR US TO TOP OUT WITHIN A COUPLE OF DEGREES
EITHER SIDE OF 60.
FRIDAY...AS THE LOW TO THE NORTH PUSHES EAST...A TRAILING COLD FRONT
WILL MOVE APPROACH LATE IN THE DAY. BUT GIVEN THAT THE FLOW ALOFT
IS GENERAL ZONAL AND ANY SHORT WAVE ENERGY REMAINS NORTH...THE FRONT
LOOKS TO COME THROUGH DRY. COMPRESSIONAL HEATING AHEAD OF THE
FRONT...AND OFFSHORE FLOW AND 850 MB TEMPS CLIMBING TO NEAR 9-10 C
WILL BOOST AFTERNOON READINGS TO THE LOWER AND MIDDLE 60S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
QUASI-ZONAL FLOW OR EVEN SHORT WAVE RIDGING ALOFT WILL PREVAIL LATE
THIS WEEK...BEFORE THE PATTERN SHOWS SIGNS OF CHANGING EARLY NEXT
WEEK. THE MID/UPPER SLOW WILL SEE THE FORMATION OF A TROUGH IN THE
EAST AND RIDGING OUT WEST. THIS WILL ALLOW FOR SOME COLDER AIR TO
INVADE THE EASTERN UNITED STATES...BUT TO WHAT MAGNITUDE HAS YET TO
BE DETERMINED. AS THE PATTERN ALOFT TRANSITIONS OVER WE WILL SEE A
COLD FRONT MOVING THROUGH EARLY NEXT WEEK...ALTHOUGH THERE ARE SOME
TIMING UNCERTAINTIES AND AS TO WHETHER OR NOT IT WILL COME THROUGH
DRY OR WITH SOME PRECIP. FOR NOW WE PREFER TO KEEP A DRY FORECAST
GOING THROUGH TUESDAY...CAPPING POPS EARLY NEXT WEEK AT A SILENT 14
PERCENT. TEMPS WILL BE ABOVE NORMAL THROUGH THE WEEKEND...THEN TREND
TOWARD BELOW NORMAL LEVELS MONDAY AND TUESDAY OR NEXT WEEK.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS EARLY IN THE TAF PERIOD WILL GIVE WAY TO PREVAILING
MVFR WEATHER STARTING AROUND 1330-1430Z AT THE TERMINALS. THIS
WILL RESULT FROM A WIDE BAND OF SHRA AND POSSIBLE TSRA IN ADVANCE
OF A STRONG COLD FRONT THAT PUSHES THROUGH EARLY THIS AFTERNOON.
IFR CONDITIONS CANNOT BE RULED OUT...BUT PROBABILITIES FAVOR MVFR
WEATHER WILL PREVAIL. VFR CONDITIONS THEN RETURN IN WAKE OF THE
COLD FRONT BEGINNING AROUND 1730-1830Z...AND WILL REMAIN VFR
THROUGH 12Z WEDNESDAY.
WINDS WILL BE OF GREAT CONCERN TODAY INTO TONIGHT WITH THE PASSAGE
OF A STRONG LOW LEVEL JET...AS HIGH AS 45-55 KT THIS MORNING...AND
30-40 KT THIS AFTERNOON INTO TONIGHT. AS SUCH...BOTH TERMINALS
WILL EXPERIENCE EITHER WIND SHEAR AND/OR STRONG GUSTY WINDS
THROUGH MOST IF NOT THE ENTIRE TAF PERIOD.
EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL.
&&
.MARINE...
TODAY...AN AREA OF LOW PRESSURE WILL MOVE NORTHWARD INTO THE CENTRAL
APPALACHIANS WITH A STRONG COLD FRONT MOVING INTO THE REGION THIS
MORNING. AS IT DOES SO...A POWERFUL LOW LEVEL JET WITH PUSH ACROSS
THE LOCAL WATERS SETTING UP THE CONDITIONS FOR A STRONG WIND EVENT.
AFTER ANALYZING MODEL SOUNDINGS FOR THE LOCAL WATERS...CONFIDENCE
HAS INCREASED SUFFICIENTLY TO UPGRADE THE SCA/S TO GALE WARNINGS FOR
THE OUTER GA WATERS...THE NEARSHORE CHARLESTON WATERS...AND THE
CHARLESTON HARBOR. FREQUENT GUSTS TO 35 KTS CAN BE EXPECTED IN THESE
AREAS BEGINNING JUST AFTER SUNRISE AND CONTINUING THROUGH THE DAY.
CONDITIONS WILL BE CLOSE TO GALE WARNING CRITERIA FOR THE REMAINDER
OF THE NEARSHORE WATERS BUT CONFIDENCE ISN/T AS HIGH THERE.
CONDITIONS WILL NEED TO MONITORED FOR POSSIBLE UPGRADES TO AMZ 352
AND 354. WINDS JUST AHEAD OF THE MAIN PRECIP BAND BE OUT OF THE
S...WITH SOME EVEN HIGHER GUSTS POSSIBLE IN ANY THUNDERSTORMS THE
DEVELOP WITHIN THE BAND. THE MAIN AREA OF PRECIP SHOULD CLEAR MOST
OF THE WATERS BY THE EARLY AFTERNOON AND WINDS WILL BECOME MORE SW
BEHIND IT. SEAS WILL BUILD THROUGH THE DAY AND WILL REACH UP TO 8
FEET CLOSE TO 20 NM ACROSS THE NEARSHORE CHARLESTON WATERS.
CONCERNING A POSSIBLE HIGH SURF ADVISORY...IT STILL LOOKS LIKE THE
DURATION OF SOUTHERLY FETCH WILL BE TOO SHORT TO MAKE AN ADVISORY
NECESSARY.
TONIGHT...COLD ADVECTION WILL INTENSIFY IN WAKE OF THE COLD FRONT
AND DEPARTING LOW TO THE DISTANT NORTH...AND WE ARE LOOKING AT SOLID
SCA/S FOR ALL WATERS FROM 0-20 NM AND IN THE CHARLESTON HARBOR.
IT/LL BE CLOSE TO GALES ACROSS THESE WATERS...BUT IT LOOKS LIKE ANY
FREQUENCY OF GUSTS WILL BE CLOSER TO 30 KT RATHER THAN 35 KT. ACROSS
THE OUTER GA WATERS...ANY DECREASE IN WINDS THIS EVENING WILL ONLY
BE TEMPORARY AS EXCELLENT MIXING ALLOWS FOR GALE FORCE GUSTS TO
AGAIN ARRIVE ACROSS AMZ374. THE OFFSHORE FETCH WILL ALLOW FOR SEAS
TO REMAIN UNDER 5 OR 6 FT WITHIN 20 NM OF SHORE...BUT WILL STILL
REACH AS HIGH AS 8 OR 9 FT OUT NEAR 60 NM OFFSHORE.
WEDNESDAY...MARINE CONDITIONS WILL RAPIDLY IMPROVE DURING THE
MORNING AS COLD ADVECTION WANES AND THE PRESSURE GRADIENT BEGINS TO
RELAX AS HIGH PRESSURE BUILDS IN FROM THE WEST. ALL HEADLINES WILL
COME DOWN BY NO LATER THAN 10-11 AM.
THURSDAY THROUGH FRIDAY...RELATIVELY QUIET CONDITIONS WILL PREVAIL
WITH HIGH PRESSURE OVER OR JUST SOUTH OF THE MARINE AREA...AND A
MAINLY OFFSHORE FLOW TO PREVAIL. A COLD FRONT LOOKS TO MOVE THROUGH
LATE FRIDAY OR FRIDAY NIGHT. WINDS AND SEAS WILL BE NOWHERE NEAR
ANY SCA CRITERIA.
SATURDAY THROUGH SUNDAY...HIGH PRESSURE WILL BUILD FROM THE
NORTH...AND THEN SLIDES EAST INTO THE ATLANTIC. ALTHOUGH AN OFFSHORE
FLOW DEVELOPS...WIND SPEEDS WILL REACH NO MORE THAN 10 OR 15
KT...AND SEAS WILL BE LIMITED TO ONLY 2 OR 3 FT.
MONDAY THROUGH TUESDAY...IT LOOKS LIKE ANOTHER COLD FRONT WILL
IMPACT THE AREA EARLY NEXT WEEK...FOLLOWED BY STRONG HIGH PRESSURE
FROM THE WEST AND NW. WINDS AND SEAS WILL RISE...AND ALTHOUGH
PROBABILITIES ARE LOW...WE CAN/T RULE OUT THE POSSIBILITY OF SOME
SCA/S WITHIN THE COLDER AIR REGIME.
&&
.TIDES/COASTAL FLOODING...
THE MORNING HIGH TIDE IN CHARLESTON WILL COME VERY CLOSE TO THE
SHALLOW COASTAL FLOODING CRITERIA OF 7.0 FT MLLW. RECENT TRENDS OF
THE TIDAL DEPARTURE SHOWS THAT LEVELS ARE RUNNING NEAR OR A LITTLE
ABOVE 1.0 FT MLLW ABOVE PREDICTED. WITH THE PREDICTED TIDE OF 6.04
FT AT 944 AM...WE HAVE OPTED TO ISSUE A COASTAL FLOOD ADVISORY
UNTIL 11 AM FOR CHARLESTON AND COASTAL COLLETON COUNTIES.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
SC...WIND ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR SCZ044-045-
048>050-052.
COASTAL FLOOD ADVISORY UNTIL 11 AM EST THIS MORNING FOR SCZ049-
050.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST WEDNESDAY FOR AMZ352.
GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR AMZ330-350.
SMALL CRAFT ADVISORY UNTIL 4 AM EST WEDNESDAY FOR AMZ354.
GALE WARNING UNTIL 4 AM EST WEDNESDAY FOR AMZ374.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
241 PM CST TUE DEC 27 2011
.DISCUSSION...
1240 PM CST
FOR UPDATE...
HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO
END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST
PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS
JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN
THE PAST HOUR OR TWO.
MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR
SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE
LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO
THIS EVENING FOR NORTHWEST INDIANA.
UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS
SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS...
COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO
STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW
ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL
INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT
POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH
THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK
RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST
SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO
EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF
THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN
END TO ANY LINGERING LIGHT PCPN.
LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY
MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850
DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF
DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH
SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE
AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY
NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION
POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN
DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST
CONVERGENCE SHIFTING EAST.
RATZER
//PREV DISCUSSION...
330 AM CST
THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH
PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE
LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS
AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE
NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP
THE FORECAST INTERESTING LOOKING FORWARD.
SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER
STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND
ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST
INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE
REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF
MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED
/AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW
REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH
UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH
ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL
COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF
SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING
PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE
LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY.
THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE
AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR
TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO
KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS
MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND
RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST
CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR
SO...NO ACCUMULATION IS EXPECTED.
THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF
THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS
AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A
CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN
CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED
EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE
THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT
AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING
IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA.
TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A
BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND
THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT
WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU
IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY
RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL
SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME
LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM
NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE
ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST
MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID-
LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT
850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND
EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE
POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE.
THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE
LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP
SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR
CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO
SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD
GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH
SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS
FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS
BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO
THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL
SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH
SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE
LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE
OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL
SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE
VALUES.
BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE
INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA.
THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C
ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED
TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S.
WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE
WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH.
BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE.
THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD
OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN
SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN
FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE
PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION.
LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER
TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND
ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN
GENERAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* GUSTY NNW WINDS THIS AFTERNOON AND EVENING.
* CIG TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING
OUT THIS EVENING.
* CHANCES FOR FLURRIES THIS AFTERNOON. BMD
//DISCUSSION...UPDATED 18Z...
COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS
CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR
AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO
SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS
WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO
INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS
NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION
INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP
MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND
GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT
GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL
INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT
RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE
20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR
ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS
ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL
CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO
WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO
THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON
SPEEDS/GUSTS AND TIMING.
* MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS
TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION.
* MEDIUM CONFIDENCE IN CIG TRENDS. BMD
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...VFR.
* THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING
WITH LIGHT SNOW.
* FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT
SNOW.
* SATURDAY...VFR.
* SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW.
* MONDAY...SLIGHT CHANCE OF LIGHT SNOW.
PAW
&&
.MARINE...
239 PM CST
THE AREA OF LOW PRESSURE HAS MOVED OVER OHIO...BUT PRESSURE RISES
AND A TIGHT PRESSURE GRADIENT BEHIND THE LOW HAS CAUSED WINDS TO
STRENGTHEN THROUGHOUT THE DAY TODAY. GALES TO 45 KT ARE POSSIBLE
THROUGH THE EARLY PART OF TONIGHT ACROSS THE ENTIRE LAKE. AS THE
LOW MOVES NORTHWARD THROUGH THE NEW ENGLAND AREA TONIGHT...THE
PRESSURE GRADIENT WILL WEAKEN AND WINDS WILL DIMINISH. HIGH
PRESSURE ALSO MOVES IN BEHIND THE LOW ON WEDNESDAY...WHICH WILL ALSO
HELP WINDS WEAKEN QUICKLY. WAVES ON THE OTHER HAND WILL REMAIN HIGH
ESPECIALLY OVER THE SOUTHERN HALF OF THE LAKE AND IN THE NORTHERN
INDIANA NEARSHORE ZONES THROUGH EARLY WEDNESDAY AFTERNOON. A
WEAKENING CLIPPER SYSTEM WILL MOVE INTO NORTH DAKOTA WEDNESDAY NIGHT
AND REACH LAKE MICHIGAN THURSDAY AFTERNOON. THE PRESSURE GRADIENT
LOOKS VERY WEAK WITH THIS SYSTEM...THEREFORE NOT ANTICIPATING
GALES. A WEAK RIDGE OF HIGH PRESSURES QUICKLY PASSES THROUGH REGION
FRIDAY NIGHT INTO SATURDAY MORNING. THE PATTERN REMAINS ACTIVE
THROUGH THE LONG TERM...WITH THE NEXT CHANCE FOR GALES LATE
THIS WEEKEND INTO EARLY NEXT WEEK AS A LARGE LOW PRESSURE SYSTEM
PASSES NORTH OF THE GREAT LAKES.
JEE
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM
WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM
WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
202 PM CST TUE DEC 27 2011
.DISCUSSION...
1240 PM CST
FOR UPDATE...
HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO
END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST
PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS
JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN
THE PAST HOUR OR TWO.
MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR
SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE
LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO
THIS EVENING FOR NORTHWEST INDIANA.
UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS
SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS...
COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO
STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW
ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL
INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT
POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH
THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK
RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST
SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO
EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF
THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN
END TO ANY LINGERING LIGHT PCPN.
LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY
MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850
DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF
DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH
SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE
AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY
NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION
POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN
DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST
CONVERGENCE SHIFTING EAST.
RATZER
//PREV DISCUSSION...
330 AM CST
THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH
PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE
LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS
AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE
NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP
THE FORECAST INTERESTING LOOKING FORWARD.
SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER
STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND
ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST
INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE
REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF
MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED
/AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW
REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH
UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH
ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL
COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF
SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING
PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE
LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY.
THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE
AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR
TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO
KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS
MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND
RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST
CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR
SO...NO ACCUMULATION IS EXPECTED.
THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF
THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS
AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A
CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN
CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED
EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE
THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT
AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING
IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA.
TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A
BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND
THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT
WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU
IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY
RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL
SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME
LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM
NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE
ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST
MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID-
LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT
850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND
EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE
POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE.
THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE
LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP
SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR
CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO
SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD
GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH
SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS
FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS
BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO
THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL
SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH
SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE
LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE
OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL
SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE
VALUES.
BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE
INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA.
THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C
ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED
TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S.
WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE
WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH.
BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE.
THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD
OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN
SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN
FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE
PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION.
LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER
TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND
ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN
GENERAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* GUSTY NNW WINDS THIS AFTERNOON AND EVENING.
* CIG TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING
OUT THIS EVENING.
* CHANCES FOR FLURRIES THIS AFTERNOON. BMD
//DISCUSSION...UPDATED 18Z...
COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS
CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR
AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO
SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS
WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO
INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS
NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION
INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP
MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND
GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT
GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL
INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT
RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE
20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR
ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS
ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL
CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO
WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO
THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON
SPEEDS/GUSTS AND TIMING.
* MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS
TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION.
* MEDIUM CONFIDENCE IN CIG TRENDS. BMD
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...VFR.
* THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING
WITH LIGHT SNOW.
* FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT
SNOW.
* SATURDAY...VFR.
* SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW.
* MONDAY...SLIGHT CHANCE OF LIGHT SNOW.
PAW
&&
.MARINE...
235 AM CST
AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS
SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND
SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD
FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF
IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE
NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF
COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS
FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE
SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS
IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE
ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE
STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE
ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL
THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA
FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP.
THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND
GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES
THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE
SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL
THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING.
CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE
SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL
SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO
REMAIN BELOW GALE. SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM
WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM
WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1240 PM CST TUE DEC 27 2011
.DISCUSSION...
1240 PM CST
FOR UPDATE...
HAVE MADE FEW CHANGES TO GOING FORECAST...AND THOSE MAINLY ONLY TO
END LINGERING PRECIP FROM THE WEST ACROSS THE FAR EAST/SOUTHEAST
PART OF THE CWA THIS MORNING. HAVE ALSO TWEAKED HOURLY/MAX TEMPS
JUST A BIT...WITH SEVERAL LOCATIONS HAVING TAGGED 40 DEGREES IN
THE PAST HOUR OR TWO.
MAIN NEAR TERM CONCERNS ARE POTENTIAL FOR A FEW FLURRIES OR
SPRINKLES THIS AFTERNOON...AS WELL AS THE POTENTIAL FOR A LITTLE
LIGHT LAKE EFFECT PRECIPITATION TO DEVELOP THIS AFTERNOON INTO
THIS EVENING FOR NORTHWEST INDIANA.
UPPER TROUGH CONTINUES TO DEEPEN THIS AFTERNOON AS VORT DIGS
SOUTHEAST ACROSS THE MID-MISSISSIPPI VALLEY. IN THE LOW LEVELS...
COLD ADVECTION BEGINNING TO STRENGTHEN WHICH WILL LEAD TO
STEEPENING OF LOW LEVEL LAPSE RATES IN SHALLOW MOIST LAYER BELOW
ABOUT 850 HPA. COMBINATION OF WEAK DPVA ALOFT AND WEAK LOW LEVEL
INSTABILITY IN CYCLONIC LOW LEVEL FLOW IS EXPECTED TO SUPPORT
POTENTIAL FOR A FEW FLURRIES OR SPRINKLES ACROSS THE AREA THROUGH
THE AFTERNOON. REGIONAL RADAR MOSAIC INDEED SHOWS SOME VERY WEAK
RETURNS MOVING SOUTH ACROSS PORTIONS OF EASTERN WI. FORECAST
SOUNDINGS INDICATE TOP OF MOIST LAYER ROUGHLY -8 TO -10 C...SO
EITHER P-TYPE OF --RA OR --S POSSIBLE. VORT AXIS SHIFTS EAST OF
THE AREA EARLY THIS EVENING WITH DRYING AND SUBSIDENCE BRINGING AN
END TO ANY LINGERING LIGHT PCPN.
LAKE EFFECT POTENTIAL IS NOT OVERLY IMPRESSIVE...THOUGH PREVIOUSLY
MENTIONED PROCESSES ARE EXPECTED TO GRADUALLY INCREASE LAKE TO 850
DELTA T VALUES TO 16/17 DEG/KM THIS EVENING. LOCAL HIGH-RES WRF
DEPICTS A BRIEF PERIOD OF LOW LEVEL CONVERGENCE ALONG THE SOUTH
SHORE OF THE LAKE EARLY THIS EVENING...BEFORE MOIST CONVERGENCE
AXIS SHIFTS EAST OF PORTER COUNTY. LIGHT QPF OUTPUT OVER MAINLY
NORTHERN PORTER COUNTY SUGGESTS A LITTLE MINOR ACCUMULATION
POSSIBLE...BUT WINDOW WILL PROBABLY BE FAIRLY SHORT BETWEEN
DEVELOPMENT OF BETTER LAKE-INDUCED LAPSE RATES AND BEST
CONVERGENCE SHIFTING EAST.
RATZER
&&
.PREV DISCUSSION...
330 AM CST
THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH
PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE
LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS
AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE
NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP
THE FORECAST INTERESTING LOOKING FORWARD.
SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER
STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND
ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST
INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE
REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF
MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED
/AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW
REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH
UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH
ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL
COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF
SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING
PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE
LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY.
THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE
AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR
TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO
KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS
MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND
RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST
CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR
SO...NO ACCUMULATION IS EXPECTED.
THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF
THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS
AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A
CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN
CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED
EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE
THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT
AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING
IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA.
TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A
BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND
THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT
WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU
IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY
RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL
SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME
LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM
NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE
ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST
MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID-
LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT
850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND
EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE
POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE.
THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE
LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP
SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR
CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO
SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD
GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH
SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS
FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS
BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO
THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL
SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH
SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE
LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE
OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL
SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE
VALUES.
BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE
INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA.
THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C
ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED
TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S.
WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE
WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH.
BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE.
THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD
OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN
SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN
FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE
PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION.
LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER
TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND
ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN
GENERAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* GUSTY NNW WINDS THIS AFTERNOON AND EVENING.
* CIGS TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING
OUT LATE THIS EVENING.
* CHANCES FOR FLURRIES THIS AFTERNOON. BMD
//DISCUSSION...UPDATED 18Z...
COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS
CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR
AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO
SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS
WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO
INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS
NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION
INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP
MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND
GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT
GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL
INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT
RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE
20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR
ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS
ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL
CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO
WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO
THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM TO HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE PERIOD.
* HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON
SPEEDS/GUSTS AND TIMING.
* MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS
TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. BMD
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...VFR.
* THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING
WITH LIGHT SNOW.
* FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT
SNOW.
* SATURDAY...VFR.
* SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW.
* MONDAY...SLIGHT CHANCE OF LIGHT SNOW.
PAW
&&
.MARINE...
235 AM CST
AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS
SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND
SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD
FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF
IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE
NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF
COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS
FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE
SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS
IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE
ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE
STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE
ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL
THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA
FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP.
THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND
GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES
THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE
SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL
THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING.
CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE
SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL
SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO
REMAIN BELOW GALE. SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM
WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM
WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1141 AM CST TUE DEC 27 2011
.DISCUSSION...
330 AM CST
THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH
PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE
LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS
AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE
NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP
THE FORECAST INTERESTING LOOKING FORWARD.
SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER
STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND
ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST
INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE
REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF
MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED
/AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW
REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH
UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH
ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL
COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF
SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING
PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE
LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY.
THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE
AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR
TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO
KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS
MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND
RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST
CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR
SO...NO ACCUMULATION IS EXPECTED.
THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF
THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS
AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A
CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN
CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED
EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE
THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT
AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING
IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA.
TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A
BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND
THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT
WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU
IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY
RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL
SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME
LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM
NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE
ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST
MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID-
LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT
850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND
EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE
POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE.
THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE
LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP
SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR
CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO
SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD
GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH
SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS
FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS
BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO
THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL
SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH
SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE
LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE
OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL
SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE
VALUES.
BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE
INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA.
THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C
ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED
TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S.
WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE
WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH.
BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE.
THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD
OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN
SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN
FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE
PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION.
LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER
TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND
ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN
GENERAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* GUSTY NNW WINDS THIS AFTERNOON AND EVENING.
* CIGS TRENDS THROUGH THE DAY...TIMING LOW LEVEL MOISTURE CLEARING
OUT LATE THIS EVENING.
* CHANCES FOR FLURRIES THIS AFTERNOON. BMD
//DISCUSSION...UPDATED 18Z...
COLD FRONT HAS SLID SOUTHEAST THROUGH THE FORECAST AREA WITH WINDS
CHANGING TO THE NW/NNW BEHIND. UPSTREAM OBSERVATIONS SHOW DRY AIR
AND GUSTY WINDS PUSHING SOUTHEAST BEHIND THE FRONT AND HELPING TO
SCOUR OUT SOME OF THE LOW LEVEL MOISTURE. UPSTREAM STRATUS DECK/CIGS
WHICH WERE MVFR HAVE GENERALLY IMPROVED TO VFR AND LENDS TO
INCREASED CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS
NORTHERN ILLINOIS THROUGH THE REMAINDER OF THE DAY. COLD ADVECTION
INTO THE AREA WILL STEEPEN LOW LEVEL LAPSE RATES ALLOWING FOR DEEP
MIXING THIS AFTERNOON. FORECAST SOUNDINGS CONTINUE TO INDICATE WIND
GUSTS WILL INCREASE INTO THE UPPER 20KT RANGE WITH OCCASIONAL 30KT
GUSTS NOT OUTSIDE THE REALM OF POSSIBILITY. VERY SHALLOW LOW LEVEL
INSTABILITY IS ALSO INDICATED BY THE FORECAST SOUNDINGS AND CANNOT
RULE OUT A FEW FLURRIES DEVELOPING THIS AFTERNOON...MAINLY IN THE
20Z-23Z WINDOW. SOME LIGHT RETURNS ARE ALREADY SHOWING UP ON RADAR
ACROSS WEST/SOUTHWEST WISCONSIN LATE THIS MORNING. NO ACCUMULATIONS
ARE EXPECTED...NOR ANY VIS RESTRICTIONS. LOW LEVEL MOISTURE WILL
CONTINUE TO ERODE THROUGH THE EVENING AS SURFACE RIDGE BEGINS TO
WORK IN FROM THE WEST. BY WEDNESDAY...WINDS WILL BEGIN TO BACK TO
THE WEST AND WEAKEN AS HIGH PRESSURE BUILDS ACROSS THE REGION. BMD
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* MEDIUM TO HIGH CONFIDENCE IN VFR CONDITIONS THROUGH THE PERIOD.
* HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON
SPEEDS/GUSTS AND TIMING.
* MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON...WITH NO IMPACTS
TO VIS. HIGH CONFIDENCE IN NO ACCUMULATION. BMD
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...VFR.
* THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING
WITH LIGHT SNOW.
* FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT
SNOW.
* SATURDAY...VFR.
* SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW.
* MONDAY...SLIGHT CHANCE OF LIGHT SNOW.
PAW
&&
.MARINE...
235 AM CST
AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS
SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND
SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD
FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF
IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE
NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF
COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS
FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE
SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS
IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE
ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE
STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE
ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL
THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA
FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP.
THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND
GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES
THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE
SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL
THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING.
CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE
SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL
SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO
REMAIN BELOW GALE. SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY.
GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM
WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM
WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1123 AM CST TUE DEC 27 2011
.DISCUSSION...
ISSUED 1010 AM CST TUE DEC 27 2011
BULK OF THE MORNING PRECIPITATION HAS MOVED OUT OF THE AREA...WITH
JUST SOME LIGHT SNOW LINGERING NEAR THE INDIANA BORDER. THIS
SHOULD MOVE OUT OVER THE NEXT HOUR. BRIEF CLEAR SLOT IS QUICKLY
FILLING IN AS A LARGE AREA OF STRATOCUMULUS DROPS SOUTHEAST ACROSS
THE WESTERN CWA. HRRR SHOWING SOME SHOWERS DEVELOPING THIS
AFTERNOON AS SECONDARY SHORTWAVE SWINGS ACROSS THE CWA...AND SOME
CONVECTIVE TYPE ECHOES ARE CURRENTLY SHOWING UP ON BOTH LINCOLN
AND DAVENPORT RADARS AS WELL AS VISIBLE SATELLITE IMAGERY. FORECAST
SOUNDINGS NOT REALLY SHOWING ANY ICE CRYSTALS LEFT...SO WILL ONLY
INCLUDE A MENTION OF SPRINKLES OR FLURRIES AT THIS TIME. SHOULD
SEE TEMPERATURES BEGIN TO STEADY OUT OR FALL BY EARLY AFTERNOON...
ESPECIALLY ACROSS THE WEST...AS COLDER AIR BEGINS TO FILTER IN
BEHIND THE SHORTWAVE.
UPDATED ZONES/GRIDS HAVE BEEN SENT.
GEELHART
&&
.AVIATION...
ISSUED 1123 AM CST TUE DEC 27 2011
EARLIER CLEAR SLOT HAS BEEN FILLING BACK IN...WITH MVFR CLOUD
CONDITIONS AT TIMES FROM KBMI-KDEC WESTWARD SLOWLY LIFTING INTO
THE VFR RANGE. WILL INCLUDE SOME TEMPO PERIODS FOR THE FIRST
COUPLE HOURS OF THE FORECAST FOR CEILINGS IN THE 2000-2500 FOOT
RANGE. STILL HAVE SOME IFR CEILINGS LINGERING AT KCMI...BUT THESE
SHOULD BE IMPROVING INTO VFR OR HIGH-END MVFR LEVELS VERY SOON.
AN UPPER LEVEL WAVE WILL BE SWEEPING ACROSS CENTRAL ILLINOIS THIS
AFTERNOON. THIS WILL SCATTER OUT THE CLOUDS EARLY THIS
EVENING...AND GUSTY NORTHWEST WINDS WILL BEGIN TO DIMINISH.
ANOTHER WEAK BOUNDARY WILL BE APPROACHING FROM THE NORTHWEST LATE
IN THE NIGHT WITH SOME MID-LEVEL CLOUDINESS ABOVE 10KFT. NORTHWEST
WINDS WILL GRADUALLY TURN TO THE SOUTHWEST AS A SURFACE RIDGE OF
HIGH PRESSURE PUSHES ACROSS THE STATE EARLY WEDNESDAY MORNING.
GEELHART
&&
.PREV DISCUSSION...
ISSUED 255 AM CST TUE DEC 27 2011
SHORT TERM...TODAY THROUGH THURSDAY
LOW PRESSURE WILL TRACK FROM WESTERN TENNESSEE EARLY THIS MORNING
INTO SOUTHERN OHIO BY MIDDAY...RESULTING IN A CONTINUATION OF LIGHT
PRECIP ACROSS THE EASTERN HALF OF THE KILX CWA THROUGH THE MORNING.
RADAR TRENDS SUGGEST BACK EDGE OF PRECIP WILL BE ALONG THE I-55
CORRIDOR BY 6 AM...THEN ALONG THE ILLINOIS/INDIANA BORDER BY NOON. A
VARIETY OF PRECIP FELL ACROSS CENTRAL ILLINOIS LAST EVENING...WITH
MANY REPORTS OF A RAIN/SNOW/SLEET MIXTURE. NAM FORECAST SOUNDINGS
INDICATE FURTHER COOLING OF THE COLUMN OVER THE NEXT FEW HOURS...
WHICH SHOULD RESULT IN PRECIP CHANGING TO MAINLY SNOW THIS MORNING.
08Z HOURLY OBS ARE BEGINNING TO SHOW THIS TREND...WITH SNOW NOW
BEING REPORTED AT A NUMBER OF SITES ACROSS EAST-CENTRAL ILLINOIS. AS
A RESULT...HAVE CARRIED CATEGORICAL POPS FOR SNOW ALONG/EAST OF I-57
THIS MORNING...WITH ACCUMULATIONS OF AN INCH OR LESS. HAVE TAPERED
POPS TO JUST LOW CHANCE ALONG I-55...AND NOTHING FURTHER WEST.
AS THE LOW PULLS AWAY AND AN APPROACHING COLD FRONT SWINGS
THROUGH...GUSTY NORTHWESTERLY WINDS WILL DEVELOP DURING THE LATE
MORNING INTO THE AFTERNOON. FORECAST SOUNDINGS SUGGEST SUSTAINED
WINDS OF 10 TO 20 MPH...WITH GUSTS AS HIGH AS 30 MPH AT TIMES. DUE
TO THE BRISK WINDS AND AMPLE CLOUD COVER...TEMPS WILL NOT WARM MUCH
TODAY...WITH HIGHS ONLY CLIMBING INTO THE UPPER 30S TO AROUND 40
DEGREES.
CHILLY WEATHER WILL BE IN STORE TONIGHT INTO WEDNESDAY...COURTESY OF
HIGH PRESSURE SLIDING THROUGH THE REGION. OVERNIGHT LOWS WILL DIP
INTO THE LOWER TO MIDDLE 20S...WHILE HIGHS ON WEDNESDAY REMAIN IN
THE UPPER 30S AND LOWER 40S.
W/NW UPPER FLOW WILL PREVAIL ACROSS THE CENTRAL/EASTERN CONUS
THROUGH THURSDAY...WITH A NUMBER OF WEAK IMPULSES DROPPING THROUGH
THE PREVAILING FLOW PATTERN. THE FIRST WAVE WILL TRACK ACROSS THE
UPPER MIDWEST/GREAT LAKES WEDNESDAY NIGHT...WITH ANY ASSOCIATED
PRECIP REMAINING WELL NORTH OF CENTRAL ILLINOIS. A SECOND STRONGER
WAVE IS EXPECTED TO DIG A BIT FURTHER SOUTH THURSDAY NIGHT...POSSIBLY
BRINGING LIGHT PRECIP AS FAR SOUTH AS THE I-74 CORRIDOR. THANKS TO A
SOUTHERLY FLOW AHEAD OF THE SYSTEM...TEMPS WILL BE WARM ENOUGH TO
SUPPORT A RAIN/SNOW MIX. THINK STRONGEST DYNAMICS WILL REMAIN ACROSS
NORTHERN ILLINOIS...HOWEVER HAVE INCLUDED SLIGHT CHANCE POPS
ALONG/NORTH OF I-74.
LONG TERM...FRIDAY THROUGH MONDAY
STILL QUITE A BIT OF MODEL DISCREPANCY IN THE EXTENDED...SO FORECAST
CONFIDENCE REMAINS LOW BEYOND SATURDAY. ECMWF CONTINUES TO FEATURE
AN AGGRESSIVELY DIGGING UPPER TROUGH ACROSS THE EASTERN CONUS EARLY
NEXT WEEK...WHILE THE GFS IS MUCH LESS AMPLIFIED. GIVEN POOR
AGREEMENT AND RUN-TO-RUN CONSISTENCY...HAVE OPTED TO LEAVE FORECAST
DRY...ALTHOUGH IF ECMWF PANS OUT...PRECIP WOULD BE POSSIBLE ACROSS
AT LEAST THE E/SE CWA SUNDAY INTO MONDAY. REGARDLESS OF WHICH MODEL
TURNS OUT TO BE RIGHT...IT APPEARS A CHUNK OF COLDER AIR IS ON THE
WAY FOR EARLY NEXT WEEK. IF THE ECMWF VERIFIES...TEMPS COULD BE WELL
BELOW NORMAL. AT THIS TIME...WILL REMAIN CONSERVATIVE AND ONLY DROP
TEMPS BACK DOWN TO NEAR NORMAL BY MONDAY.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1012 AM CST TUE DEC 27 2011
.DISCUSSION...
ISSUED 1010 AM CST TUE DEC 27 2011
BULK OF THE MORNING PRECIPITATION HAS MOVED OUT OF THE AREA...WITH
JUST SOME LIGHT SNOW LINGERING NEAR THE INDIANA BORDER. THIS
SHOULD MOVE OUT OVER THE NEXT HOUR. BRIEF CLEAR SLOT IS QUICKLY
FILLING IN AS A LARGE AREA OF STRATOCUMULUS DROPS SOUTHEAST ACROSS
THE WESTERN CWA. HRRR SHOWING SOME SHOWERS DEVELOPING THIS
AFTERNOON AS SECONDARY SHORTWAVE SWINGS ACROSS THE CWA...AND SOME
CONVECTIVE TYPE ECHOES ARE CURRENTLY SHOWING UP ON BOTH LINCOLN
AND DAVENPORT RADARS AS WELL AS VISIBLE SATELLITE IMAGERY. FORECAST
SOUNDINGS NOT REALLY SHOWING ANY ICE CRYSTALS LEFT...SO WILL ONLY
INCLUDE A MENTION OF SPRINKLES OR FLURRIES AT THIS TIME. SHOULD
SEE TEMPERATURES BEGIN TO STEADY OUT OR FALL BY EARLY AFTERNOON...
ESPECIALLY ACROSS THE WEST...AS COLDER AIR BEGINS TO FILTER IN
BEHIND THE SHORTWAVE.
UPDATED ZONES/GRIDS HAVE BEEN SENT.
GEELHART
&&
.AVIATION...
ISSUED 518 AM CST TUE DEC 27 2011
UPPER LOW OVER NORTHERN MS WITH LARGE AREA OF MIXED PRECIPITATION
EXTENDING NORTH THROUGH IL...MAINLY ALONG AND EAST OF INTERSTATE 55.
BACK EDGE OF THE RAIN/SNOW IS MAKING STEADY PROGRESS AND WILL BE
EAST OF SPI/BMI BY 13Z...DEC BY 14Z...AND CMI AROUND 16Z. A PERIOD
OF CIGS BELOW 500 FT AND 3-5SM FOG WILL FOLLOW THE PRECIPITATION FOR
A COUPLE OF HOURS...WITH TEMPORARY VFR CONDITIONS THEREAFTER. A COLD
FRONT MOVING INTO EASTERN IA WILL MOVE THROUGH CENTRAL IL BEFORE
18Z. SATELLITE IMAGERY SHOWS ANOTHER BATCH OF MVFR STRATOCU MOVING
SOUTHEAST INTO NORTHERN IA BEHIND THE FRONT...AND THE SHORT RANGE
MODELS INDICATE THAT THESE CLOUDS WILL CONTINUE INTO CENTRAL IL.
WINDS AFTER FRONTAL PASSAGE WILL INCREASE FROM THE NORTHWEST AT
20-25 KT WITH HIGHER GUSTS. UPSTREAM PROFILERS ARE SHOWING 925 MB
WINDS OF 30-35 KT AT THIS TIME. CLOUDS WILL MOVE OUT AND WINDS WILL
DIMINISH BETWEEN 00Z AND 03Z WED. AT THIS TIME...SIGNIFICANT FOG
APPEARS UNLIKELY TONIGHT DUE TO THE DRIER SURFACE DEWPOINTS AND
SUFFICIENT BREEZE TO KEEP THE AIR MIXED.
04
&&
.PREV DISCUSSION...
ISSUED 255 AM CST TUE DEC 27 2011
SHORT TERM...TODAY THROUGH THURSDAY
LOW PRESSURE WILL TRACK FROM WESTERN TENNESSEE EARLY THIS MORNING
INTO SOUTHERN OHIO BY MIDDAY...RESULTING IN A CONTINUATION OF LIGHT
PRECIP ACROSS THE EASTERN HALF OF THE KILX CWA THROUGH THE MORNING.
RADAR TRENDS SUGGEST BACK EDGE OF PRECIP WILL BE ALONG THE I-55
CORRIDOR BY 6 AM...THEN ALONG THE ILLINOIS/INDIANA BORDER BY NOON. A
VARIETY OF PRECIP FELL ACROSS CENTRAL ILLINOIS LAST EVENING...WITH
MANY REPORTS OF A RAIN/SNOW/SLEET MIXTURE. NAM FORECAST SOUNDINGS
INDICATE FURTHER COOLING OF THE COLUMN OVER THE NEXT FEW HOURS...
WHICH SHOULD RESULT IN PRECIP CHANGING TO MAINLY SNOW THIS MORNING.
08Z HOURLY OBS ARE BEGINNING TO SHOW THIS TREND...WITH SNOW NOW
BEING REPORTED AT A NUMBER OF SITES ACROSS EAST-CENTRAL ILLINOIS. AS
A RESULT...HAVE CARRIED CATEGORICAL POPS FOR SNOW ALONG/EAST OF I-57
THIS MORNING...WITH ACCUMULATIONS OF AN INCH OR LESS. HAVE TAPERED
POPS TO JUST LOW CHANCE ALONG I-55...AND NOTHING FURTHER WEST.
AS THE LOW PULLS AWAY AND AN APPROACHING COLD FRONT SWINGS
THROUGH...GUSTY NORTHWESTERLY WINDS WILL DEVELOP DURING THE LATE
MORNING INTO THE AFTERNOON. FORECAST SOUNDINGS SUGGEST SUSTAINED
WINDS OF 10 TO 20 MPH...WITH GUSTS AS HIGH AS 30 MPH AT TIMES. DUE
TO THE BRISK WINDS AND AMPLE CLOUD COVER...TEMPS WILL NOT WARM MUCH
TODAY...WITH HIGHS ONLY CLIMBING INTO THE UPPER 30S TO AROUND 40
DEGREES.
CHILLY WEATHER WILL BE IN STORE TONIGHT INTO WEDNESDAY...COURTESY OF
HIGH PRESSURE SLIDING THROUGH THE REGION. OVERNIGHT LOWS WILL DIP
INTO THE LOWER TO MIDDLE 20S...WHILE HIGHS ON WEDNESDAY REMAIN IN
THE UPPER 30S AND LOWER 40S.
W/NW UPPER FLOW WILL PREVAIL ACROSS THE CENTRAL/EASTERN CONUS
THROUGH THURSDAY...WITH A NUMBER OF WEAK IMPULSES DROPPING THROUGH
THE PREVAILING FLOW PATTERN. THE FIRST WAVE WILL TRACK ACROSS THE
UPPER MIDWEST/GREAT LAKES WEDNESDAY NIGHT...WITH ANY ASSOCIATED
PRECIP REMAINING WELL NORTH OF CENTRAL ILLINOIS. A SECOND STRONGER
WAVE IS EXPECTED TO DIG A BIT FURTHER SOUTH THURSDAY NIGHT...POSSIBLY
BRINGING LIGHT PRECIP AS FAR SOUTH AS THE I-74 CORRIDOR. THANKS TO A
SOUTHERLY FLOW AHEAD OF THE SYSTEM...TEMPS WILL BE WARM ENOUGH TO
SUPPORT A RAIN/SNOW MIX. THINK STRONGEST DYNAMICS WILL REMAIN ACROSS
NORTHERN ILLINOIS...HOWEVER HAVE INCLUDED SLIGHT CHANCE POPS
ALONG/NORTH OF I-74.
LONG TERM...FRIDAY THROUGH MONDAY
STILL QUITE A BIT OF MODEL DISCREPANCY IN THE EXTENDED...SO FORECAST
CONFIDENCE REMAINS LOW BEYOND SATURDAY. ECMWF CONTINUES TO FEATURE
AN AGGRESSIVELY DIGGING UPPER TROUGH ACROSS THE EASTERN CONUS EARLY
NEXT WEEK...WHILE THE GFS IS MUCH LESS AMPLIFIED. GIVEN POOR
AGREEMENT AND RUN-TO-RUN CONSISTENCY...HAVE OPTED TO LEAVE FORECAST
DRY...ALTHOUGH IF ECMWF PANS OUT...PRECIP WOULD BE POSSIBLE ACROSS
AT LEAST THE E/SE CWA SUNDAY INTO MONDAY. REGARDLESS OF WHICH MODEL
TURNS OUT TO BE RIGHT...IT APPEARS A CHUNK OF COLDER AIR IS ON THE
WAY FOR EARLY NEXT WEEK. IF THE ECMWF VERIFIES...TEMPS COULD BE WELL
BELOW NORMAL. AT THIS TIME...WILL REMAIN CONSERVATIVE AND ONLY DROP
TEMPS BACK DOWN TO NEAR NORMAL BY MONDAY.
BARNES
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1004 AM CST TUE DEC 27 2011
.DISCUSSION...
330 AM CST
THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH
PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE
LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS
AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE
NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP
THE FORECAST INTERESTING LOOKING FORWARD.
SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER
STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND
ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST
INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE
REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF
MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED
/AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW
REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH
UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH
ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL
COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF
SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING
PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE
LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY.
THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE
AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR
TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO
KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS
MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND
RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST
CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR
SO...NO ACCUMULATION IS EXPECTED.
THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF
THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS
AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A
CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN
CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED
EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE
THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT
AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING
IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA.
TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A
BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND
THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT
WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU
IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY
RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL
SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME
LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM
NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE
ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST
MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID-
LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT
850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND
EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE
POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE.
THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE
LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP
SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR
CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO
SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD
GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH
SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS
FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS
BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO
THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL
SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH
SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE
LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE
OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL
SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE
VALUES.
BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE
INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA.
THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C
ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED
TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S.
WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE
WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH.
BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE.
THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD
OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN
SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN
FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE
PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION.
LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER
TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND
ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN
GENERAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* CIG TRENDS...POTENTIAL FOR MVFR CONDITIONS TO RETURN.
* STRONG GUSTY NNW WINDS.
* POSSIBILITY OF FLURRIES THIS AFTERNOON. BMD
//DISCUSSION...UPDATED 12Z...
AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS
HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY
MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY
MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE
JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND
A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN
THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND
INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND
THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* MEDIUM CONFIDENCE ON VFR CONDITIONS PREVAILING REMAINDER OF
DAY. LOW CONFIDENCE ON MVFR CONDITIONS RETURNING.
* HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON WIND
SPEEDS/GUSTS AND TIMING ARRIVAL OF GUSTS.
* LOW CONFIDENCE ON FLURRIES THIS AFTERNOON. BMD
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...VFR.
* THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING
WITH LIGHT SNOW.
* FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT
SNOW.
* SATURDAY...VFR.
* SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW.
* MONDAY...SLIGHT CHANCE OF LIGHT SNOW.
PAW
&&
.MARINE...
235 AM CST
AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS
SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND
SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD
FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF
IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE
NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF
COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS
FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE
SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS
IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE
ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE
STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE
ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL
THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA
FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP.
THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND
GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES
THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE
SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL
THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING.
CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE
SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL
SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO
REMAIN BELOW GALE. SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY.
GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM
WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM
WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
812 AM CST TUE DEC 27 2011
.DISCUSSION...
330 AM CST
THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH
PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE
LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS
AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE
NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP
THE FORECAST INTERESTING LOOKING FORWARD.
SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER
STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND
ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST
INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE
REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF
MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED
/AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW
REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH
UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH
ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL
COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF
SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING
PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE
LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY.
THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE
AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR
TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO
KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS
MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND
RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST
CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR
SO...NO ACCUMULATION IS EXPECTED.
THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF
THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS
AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A
CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN
CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED
EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE
THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT
AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING
IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA.
TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A
BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND
THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT
WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU
IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY
RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL
SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME
LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM
NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE
ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST
MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID-
LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT
850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND
EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE
POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE.
THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE
LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP
SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR
CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO
SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD
GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH
SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS
FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS
BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO
THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL
SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH
SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE
LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE
OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL
SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE
VALUES.
BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE
INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA.
THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C
ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED
TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S.
WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE
WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH.
BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE.
THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD
OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN
SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN
FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE
PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION.
LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER
TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND
ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN
GENERAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 14Z...
* CIG TRENDS THIS MORNING AND AFTERNOON...TIMING WINDOW OF VFR
CONDITIONS BEFORE HIGHER END MVFR CONDITIONS RETURN.
* STRONG GUSTY NNW WINDS.
* POSSIBILITY OF FLURRIES THIS AFTERNOON.
BMD
//DISCUSSION...UPDATED 12Z...
AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS
HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY
MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY
MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE
JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND
A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN
THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND
INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND
THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 14Z...
* MEDIUM CONFIDENCE ON SOME WINDOW OF IFR CONDITIONS...LOW
CONFIDENCE ON SPECIFIC TIMING.
* HIGH CONFIDENCE THAT ONCE CIGS LIFT ABOVE 015...WILL STAY ABOVE
015.
* HIGH CONFIDENCE ON WIND DIRECTION...MEDIUM CONFIDENCE ON WIND
SPEEDS/GUSTS.
* LOW CONFIDENCE ON FLURRIES THIS AFTERNOON.
BMD
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...VFR.
* THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING
WITH LIGHT SNOW.
* FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT
SNOW.
* SATURDAY...VFR.
* SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW.
* MONDAY...SLIGHT CHANCE OF LIGHT SNOW.
PAW
&&
.MARINE...
235 AM CST
AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS
SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND
SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD
FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF
IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE
NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF
COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS
FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE
SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS
IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE
ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE
STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE
ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL
THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA
FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP.
THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND
GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES
THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE
SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL
THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING.
CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE
SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL
SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO
REMAIN BELOW GALE. SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY.
GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON
TUESDAY TO 3 AM WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM
WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
533 AM CST TUE DEC 27 2011
.DISCUSSION...
330 AM CST
THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH
PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE
LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS
AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE
NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP
THE FORECAST INTERESTING LOOKING FORWARD.
SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER
STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND
ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST
INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE
REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF
MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED
/AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW
REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH
UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH
ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL
COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF
SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING
PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE
LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY.
THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE
AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR
TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO
KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS
MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND
RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST
CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR
SO...NO ACCUMULATION IS EXPECTED.
THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF
THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS
AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A
CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN
CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED
EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE
THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT
AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING
IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA.
TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A
BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND
THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT
WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU
IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY
RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL
SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME
LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM
NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE
ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST
MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID-
LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT
850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND
EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE
POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE.
THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE
LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP
SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR
CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO
SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD
GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH
SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS
FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS
BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO
THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL
SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH
SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE
LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE
OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL
SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE
VALUES.
BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE
INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA.
THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C
ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED
TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S.
WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE
WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH.
BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE.
THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD
OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN
SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN
FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE
PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION.
LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER
TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND
ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN
GENERAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* TIMING OF PRECIPITATION ENDING AT MDW THIS MORNING.
* POSSIBILITY OF FLURRIES THIS AFTERNOON.
* IFR CIGS IMPROVING TO MVFR BY MID MORNING.
* WIND SHIFT TO NORTHWEST MID MORNING. SPEED INCREASING AND
BECOMING GUSTY BY LATE MORNING AND CONTINUING INTO THIS EVENING.
PAW
//DISCUSSION...UPDATED 12Z...
AREAS OF RAIN AND MIXED RAIN/SNOW OVER THE CHICAGO METRO TERMINALS
HAVE DECREASED IN SIZE AND MOVED TO THE EAST THROUGH THE EARLY
MORNING HOURS AS THE LOW PRESSURE SYSTEM CENTERED OVER WESTERN KY
MOVES TO THE NORTHEAST. AS THE PRECIPITATION ENDS CIGS MAY IMPROVE
JUST A LITTLE BIT. BUT MORE SIGNIFICANT IMPROVEMENT WILL BE BEHIND
A COLD FRONT THAT WILL MOVE ACROSS NORTHERN IL AND NORTHWEST IN
THIS MORNING. THIS FRONT WILL TURN WINDS TO THE NORTHWEST AND
INCREASE THE SPEEDS BY LATE MORNING. FLURRIES ARE POSSIBLE BEHIND
THE FRONT IN THE COLDER AIR AT ALL THE TERMINALS THIS AFTERNOON.
PAW
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE IN ALL PRECIPITATION.
* MEDIUM CONFIDENCE IN TIMING OF IFR CIG IMPROVEMENT.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...VFR.
* THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING
WITH LIGHT SNOW.
* FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT
SNOW.
* SATURDAY...VFR.
* SUNDAY...SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW.
* MONDAY...SLIGHT CHANCE OF LIGHT SNOW.
PAW
&&
.MARINE...
235 AM CST
AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS
SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND
SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD
FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF
IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE
NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF
COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS
FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE
SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS
IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE
ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE
STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE
ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL
THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA
FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP.
THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND
GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES
THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE
SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL
THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING.
CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE
SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL
SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO
REMAIN BELOW GALE. SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL NOON TUESDAY.
GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777-
LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON
TUESDAY TO 3 AM WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM
WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
406 AM CST TUE DEC 27 2011
.DISCUSSION...
330 AM CST
THE FORECAST CHALLENGES ARE FIRST ON THE IMMEDIATE SHORT TERM WITH
PRECIPITATION GRADUALLY SHIFTING EASTWARD THIS MORNING...THEN THE
LAKE EFFECT SHOWER POTENTIAL INTO NORTHWEST INDIANA THIS
AFTERNOON AND EVENING. THE ACTIVE FLOW PATTERN ACROSS THE
NORTHERN U.S. AND SOME UNDULATIONS IN THIS INTO THE NEW YEAR KEEP
THE FORECAST INTERESTING LOOKING FORWARD.
SHORT TERM...LOW PRESSURE IS DEVELOPING FAIRLY RAPIDLY UNDER
STRONG JET SUPPORT ACROSS WESTERN KY. MOIST ADVECTION ALOFT AND
ASSOCIATED ASCENT CONTINUES TO WORK ITS WAY ACROSS NORTHWEST
INDIANA. AN ELONGATED NORTHERN STREAM WAVE PUSHING EAST ACROSS THE
REGION HAS INTERACTED WITH THIS...HELPING TO PRODUCE BANDS OF
MODERATE PRECIP AT TIMES WHERE CONVERGENCE OF ECHOES WAS OBSERVED
/AND LIKELY IMPLYING FRONTOGENETIC FORCING/. WITHIN THESE...A FEW
REPORTS OF SLEET WERE OBSERVED/REPORTED OR ESTIMATED THROUGH
UNKNOWN PRECIP AUTOMATED REPORTS. STRONGER FORCING LIFTING NORTH
ACROSS EASTERN IL/WESTERN IN HAS HELPED TO LEAD TO EVAPORATIONAL
COOLING SUPPORTING SNOW...AND BENTON COUNTY REPORTED A COATING OF
SNOW ON THEIR PAVEMENT AS OF 300 AM. EXPECT THE AREAS RECEIVING
PRECIPITATION AT DAYBREAK TO BE MAINLY A WET SNOW...WITH A LITTLE
LIGHT RAIN POSSIBLY JUST BEFORE IT ENDS ON THE WESTERN PERIPHERY.
THE SHIELD OF PRECIP WILL TAKE A WHILE TO EVOLVE EAST OUT OF THE
AREA BASED ON THE QG FORCING ON THE RUC AS WELL AS WATER VAPOR
TRENDS WITH THE DRY SLOT NOSE LIFTING INTO CENTRAL IN HELPING TO
KEEP MAINLY SNOW GOING IN THE SOUTHEAST FORECAST AREA THIS
MORNING. MAXIMUM ACCUMULATIONS NEAR AN INCH TOWARDS FOWLER AND
RENSSALEAR STILL LOOK VALID. IN THE FAR SOUTH AND SOUTHEAST
CHICAGO METRO WHILE SNOW MAY STILL BE OCCURRING THROUGH 9 AM OR
SO...NO ACCUMULATION IS EXPECTED.
THIS AFTERNOON...STRONG NORTH TO NORTHWEST WINDS IN THE WAKE OF
THE SYSTEM ESTABLISH THEMSELVES DOWN THE FETCH OF LAKE MI THIS
AFTERNOON. CONVERGENCE STREAMLINES FROM THE 27.06 NAM FAVOR A
CORRIDOR OF SATURATED CONVERGENCE CENTERED ON MICHIGAN
CITY...WITH SOME FURTHER WEST TOWARDS PORTER COUNTY. LAKE INDUCED
EQUILIBRIUM LEVELS ARE PROJECTED OVER 5000 FT ON THE NAM FOR LATE
THIS AFTERNOON AND EVENING AND THUS HAVE INCREASED POPS IN THAT
AREA FOR SOME SNOW SHOWERS. FROM THIS...ONLY AN ADDITIONAL DUSTING
IS EXPECTED WITH POTENTIAL FOR MORE JUST EAST OF THE FORECAST AREA.
TONIGHT THROUGH THURSDAY...THE TEMPERATURES TONIGHT WILL BE A
BATTLE BETWEEN THE COLD AND DRY AIR ADVECTION THIS EVENING AND
THEN MID TO HIGH CLOUDS ON THE INCREASE FROM THE WEST OVERNIGHT
WITH AN APPROACHING SHORT WAVE. IN ADDITION...LINGERING STRATOCU
IN THE CAA REGIME IS LIKELY EARLY THIS EVENING...AND THAT MAY
RESIDE THROUGH A GOOD PART OF THE NIGHT IN EASTERN AREAS. MODEL
SPREAD REFLECTS THIS...VARYING UP TO TEN DEGREES IN SOME
LOCATIONS. CONFIDENCE IS THUS MINIMAL ON TONIGHTS LOWS...AND AM
NEAR THE CENTER OF THE SPREAD AT THIS TIME. A STRONGER SHORT WAVE
ARRIVES INTO SOUTHERN WI ON LATE WEDNESDAY NIGHT INTO THURSDAY
MORNING. THIS IS A TRUE QUICK MOVING CLIPPER...WITH ITS BEST
MOISTURE SUPPORT ALONG AND NORTH OF ITS PATH WHERE THE TIGHT MID-
LEVEL THERMAL GRADIENT EXISTS. WHILE THERE IS FAIRLY STOUT
850-600 MB WAA AHEAD OF THIS FEATURE WED AFTERNOON AND
EVENING...THE COLUMN LOOKS MUCH TOO DRY FOR PRECIP. SO ONLY HAVE
POPS NEAR THE WI STATE LINE WITH THE ACTUAL LOW CENTER PASSAGE.
THURSDAY NIGHT...WHAT HAD BEEN A DEEP SLOW-MOVING LOW IN THE
LONGER RANGE FORECAST DAYS AGO HAS TRENDED TOWARDS A SHARP
SOUTHEAST DIVING CLIPPER THAT STILL IS FAIRLY DEEP IN PRESSURE FOR
CLIPPERS /~1002 MB/. THE PATH ON THE GFS AND EC FAVOR OUR AREA TO
SEE SOME PRECIP...BUT EVEN A SLIGHT SHIFT NORTH OR SOUTH WOULD
GREATLY REDUCE THEM AS IT IS A FAIRLY NARROW AXIS OF PRECIP WITH
SUCH A STRUCTURE. INDEED THE 27.06 NAM IS A SOLUTION THAT IS
FURTHER NORTH WITH LITTLE QPF. THE EC FOR TWO CONSECUTIVE RUNS HAS
BEEN SLOWER THAN THE GFS...FAVORING OVERNIGHT THU AS OPPOSED TO
THE EVE FOR INFLUENCE OVER OUR AREA. BOTH MODELS WOULD STILL
SUPPORT SNOW CHANCES...BUT THE EC IS BETTER LOOKING FOR THAT WITH
SLIGHTLY DEEPER HEIGHT FALLS AND GREATER MIXING RATIOS ON THE
LIFTING SURFACES / 2.5-3 G/KG /. UNFORTUNATELY...THIS WAVE IS ONE
OF MANY IN THE NORTHERN PACIFIC RIGHT NOW AND THUS NOT WELL
SAMPLED. SO HAVE KEPT POPS ONLY AT A CHANCE BUT HAVE INCREASE
VALUES.
BEYOND...THE PROGRESSIVE PATTERN CONTINUES WITH AN IMMEDIATE
INCREASE IN HEIGHTS AND A LOW-LEVEL THERMAL RIDGE INTO THE AREA.
THE GFS...EC...AND GEM ALL BRING 850 MB TEMPERATURES TO ABOVE 8C
ON SATURDAY. BIAS-CORRECTED FORECASTS FROM THESE MODELS BLENDED
TOGETHER YIELDS HIGHS FROM THE UPPER 40S TO A STAGGERING MID 50S.
WITH SUCH A QUICK TURNAROUND FROM COOL AIR ADVECTION BEHIND THE
WAVE THURSDAY NIGHT/EARLY FRIDAY...WILL NOT BE GOING THAT HIGH.
BUT HAVE BLENDED THE GOING FORECAST ALMOST 50 PERCENT WITH THESE.
THIS AMPLIFIED PATTERN WHICH BRINGS IN THE WARMER REGIME IS AHEAD
OF A DIGGING JET TO START THE NEW YEAR WHICH HAS BEEN HINTED AT IN
SOLUTIONS FOR A WHILE. THIS WOULD AT LEAST BRING TEMPERATURES DOWN
FOR EARLY NEXT WEEK...BUT CONFIDENCE IS LOW IN THIS AS WELL AS THE
PRECIP CHANCES WITH THE SYSTEM EVOLVING ON THE JET UNDULATION.
LOOKING INTO NEXT WEEK...DESPITE THE CHANCES FOR COOLER
TEMPERATURES INITIALLY...THE 8 TO 14 DAY CPC OUTLOOK AND
ESPECIALLY THE NAEFS MEMBERS FAVOR ABOVE NORMAL TEMPERATURES IN
GENERAL.
MTF
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 10Z...
* LIGHT RAIN...POSSIBLY MIXED WITH LIGHT SNOW...ENDING AROUND
SUNRISE.
* POSSIBILITY FOR FLURRIES THIS AFTERNOON.
* IFR CIGS ASSOCIATED WITH PRECIPITATION IMPROVING TO MVFR BY MID
MORNING.
* WIND SHIFT TO NROTHWEST MID MORNING. WIND INCREASING AND
BECOMING GUSTY BY LATE MORNING AND CONTINUING INTO THIS EVENING.
PAW
//DISCUSSION...UPDATED 06Z...
LIGHT RAIN CONTINUES TO DEVELOP/SPREAD ACROSS NORTHERN IL LATE
THIS EVENING WITH THE BACK EDGE EXTENDING FROM ROUGHLY MKE TO MLI.
THIS WILL SLOWLY MOVE EAST ACROSS THE TERMINALS OVERNIGHT. LOW
PRESSURE CURRENTLY NEAR MEMPHIS WILL LIFT NORTH ACROSS THE OHIO
VALLEY THROUGH TUESDAY MORNING. AS IT DOES...ADDITIONAL PRECIP
WILL SPREAD ACROSS EASTERN IL AND NORTHWEST INDIANA...LIKELY
MIXING WITH THEN BECOMING ALL SNOW. WHEN AND WHERE THIS CHANGE
OVER OCCURS IS THE CHALLENGE AND TRENDS STILL SUPPORT THE BULK OF
THE PRECIP REMAINING JUST SOUTHEAST OF THE TERMINALS. THUS HAVE
MADE NO SIGNIFICANT CHANGES WITH PREVAILING LIGHT RAIN THROUGH THE
NIGHT WITH THE POTENTIAL TO MIX WITH SNOW OVERNIGHT.
CIGS STILL VFR ACROSS THE AREA BUT MVFR CIGS DEVELOPING ACROSS
CENTRAL IL AND AS LIGHT RAIN CONTINUES TO FALL...EXPECT CIGS TO
GRADUALLY LOWER INTO MVFR. CONFIDENCE OF EXACTLY WHEN CIGS LOWER
TO MVFR IS NOT PARTICULARLY HIGH...LIKELY IN THE 08Z-11Z TIME
PERIOD...AND THIS WILL LIKELY NEED TWEAKING WITH OVERNIGHT
UPDATES. IFR CIGS STILL POSSIBLE AND MOST LIKELY AFTER SUNRISE AS
PRECIP ENDS...BUT AHEAD OF AN APPROACHING COLD FRONT. THIS FRONT
SHOULD HELP LIFT ANY IFR CIGS BACK TO MVFR BY MID/LATE MORNING.
ONCE WINDS SHIFT TO THE NORTHWEST...SPEEDS/GUSTS SHOULD STEADILY
INCREASE AND WITH A PUSH OF COLDER AIR BY EARLY AFTERNOON...COULD
BE SOME FLURRIES OR SNOW SHOWERS. SKIES BEGIN TO CLEAR BY LATE
AFTERNOON/EARLY EVENING...AS WINDS ALSO BEGIN TO DIMINISH. CMS
//ORD AND MDW CONFIDENCE...UPDATED 10Z...
* MEDIUM CONFIDENCE IN TIMING OF PRECIPITATION ENDING THIS
MORNING.
* MEDIUM CONFIDENCE IN FLURRIES THIS AFTERNOON.
* MEDIUM CONFIDENCE IN TIMING OF IFR CIG IMPROVEMENT.
* HIGH CONFIDENCE IN WIND TREND.
PAW
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
* WEDNESDAY...VFR.
* THURSDAY...VFR. SLIGHT CHANCE OF LIGHT RAIN...POSSIBLY MIXING
WITH LIGHT SNOW.
* FRIDAY...MVFR POSSIBLE. SLIGHT CHANCE OF LIGHT RAIN OR LIGHT
SNOW.
* SATURDAY...VFR.
* SUNDAY..SLIGHT CHANCE OF LIGHT RAIN OR LIGHT SNOW. CMS
&&
.MARINE...
235 AM CST
AN AREA OF LOW PRESSURE CONTINUES TO SLOWLY MOVE EAST ACROSS
SOUTHERN ONTARIO THIS MORNING. DRAPED SOUTH FROM THIS LOW AND
SPANNING MUCH OF THE UPPER AND MIDDLE MISSISSIPPI VALLEY IS A COLD
FRONT THAT WILL SLIDE ACROSS THE LAKE LATER THIS MORNING. AHEAD OF
IT...THE 15 TO 25 KT WINDS WILL VEER TO THE WEST AND THEN TO THE
NORTHWEST THROUGH THE EARLY AFTERNOON HOURS. THE STRONGEST SURGE OF
COLD AIR IS NOT ANTICIPATED TO BE UNTIL THE LATER AFTERNOON HOURS
FOR THE NORTHERN HALF OF THE LAKE...AND SHORTLY THEREAFTER FOR THE
SOUTHERN HALF. IT IS WITH THIS SURGE THAT THE STRONGEST OF WINDS
IS ANTICIPATED. HIGH END GALES ARE AGAIN LIKELY...BUT FOR THE
ENTIRE SPAN OF THE LAKE WITH THIS EVENT AS OPPOSED TO THE
STRONGEST WINDS REMAINING NORTH YESTERDAY. FORECAST SOUNDINGS ARE
ALSO INDICATING THE POTENTIAL FOR LOW END STORM FORCE GUSTS. FEEL
THAT THE MAJORITY OF THE WINDS WILL REMAIN BELOW STORM CRITERIA
FOR THE OPEN WATERS AND WILL ONLY MENTION IN AN OCCASIONAL GROUP.
THOUGHTS THEN TURN TO NEARSHORE BURNS HARBOR TO MICHIGAN CITY IN AND 744...AND POTENTIALLY 743 AND
GALES. WITH THE STRONG NORTHWESTERLY WINDS EXPECTED...INCREASES
THE CHANCES INTO THE EVENING HOURS AND OVERNIGHT. WILL ERR ON THE
SIDE OF CAUTION FOR THE FRICTIONLESS MARINE LOCATIONS AND CANCEL
THE SMALL CRAFT FOR THOSE LOCATIONS AND HOIST A GALE WARNING.
CONDITIONS SET TO IMPROVE LATE TONIGHT AS RIDGING ACROSS THE
SURFACE BUILDS...THOUGH PROLONGED STRONG SOUTHWESTERLY FLOW WILL
SLOWLY RAMP UP THROUGH WEDNESDAY NIGHT...WITH FLOW PROGGED TO
REMAIN BELOW GALE. SHEA
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...NOON TUESDAY TO 3 AM
WEDNESDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS
UNTIL 6 PM WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
355 AM EST THU DEC 29 2011
.SHORT TERM... / TODAY THROUGH FRIDAY NIGHT /
08Z SFC ANALYSIS SHOWS A SFC LOW NEAR MSP WITH A WARM FRONT
EXTENDING SE INTO EASTERN IA AND WC IL. THE ASSOCIATED LOW
AMPLITUDE SHORTWAVE OVER THE UPPER MIDWEST WILL SHEAR OUT TOWARDS
THE CENTRAL GREAT LAKES TODAY ALLOWING THE WARM FRONT TO SURGE
NEWD INTO THE SRN GREAT LAKES. RATHER MODEST
OVERRUNNING/ISENTROPIC UPGLIDE EXPECTED JUST AHEAD OF THIS WARM
FRONT THIS MORNING INTO EARLY THIS AFTERNOON (40 KNOTS OF CROSS
ISOBARIC FLOW ON THE I290 SFC). UPSTREAM OBS/MOSAIC RADAR AND THE
BULK OF 00Z GUIDANCE SUGGEST THAT NORTHERN AREAS MAY SEE A BRIEF
PERIOD (AN HOUR OR TWO) OF VERY LIGHT PCPN THIS MORNING INTO EARLY
THIS AFTN...WITH THE BETTER CHANCES FOR MEASURABLE PCPN (A COUPLE
HUNDREDTHS AT BEST) BEING ACROSS THE NORTH/NORTHEAST WITH MAINLY
VIRGA SOUTHWEST. LATEST RUC SOUNDINGS AND SFC OBS CONTINUE TO
SUPPORT A POSSIBLE LIGHT MIX OF FREEZING DRIZZLE/SNOW TO
START...LIKELY TRANSITIONING TO A BRIEF PERIOD OF DRIZZLE. ANY
FREEZING DRIZZLE/RAIN BTW 12-15Z MAY CREATE A FEW SLICK SPOTS ON
AREA ROADS...MAINLY NORTH OF ROUTE 6. OTHERWISE...EXPECT WINDS
WILL PICK UP AND VEER BEHIND THE FRONTAL BOUNDARY WITH GUSTS OF
20-25 KNOTS POSSIBLE.
A MUCH MORE VIGOROUS SHORTWAVE NOW ACROSS THE PAC NW WILL DIG INTO
THE MID MS VALLEY AND NRN OH VALLEY BY LATER TONIGHT AND FRIDAY.
GFS/ECMWF AGREE ON 120-140 METER 500 MB HEIGHT FALLS WITH THIS
FEATURE SUPPORTING A RATHER HEALTHY LOW LVL RESPONSE AND THETA-E
ADV INTO THE AREA WITH PCPN FOCUSING ALONG A DEEPENING BAROCLINIC
ZONE. A MODEL CONSENSUS FAVORS THE NORTHERN HALF OF THE FA FOR
BEST CHANCES FOR MEASURABLE RAINFALL. AMOUNTS ARE FCST TO RANGE
BETWEEN 0.20" AND 0.50" HERE. HIRES GUIDANCE IS A LITTLE FARTHER
SOUTH WITH THE TRACK OF THIS SYSTEM SO DID CONTINUE WITH
CHC/SLIGHT WORDING FOR SNOW IN THE FAR NORTH...WITH AREAS JUST
NORTH OF THE FA IN A GOOD POSITION FOR A MODERATE SNOWFALL.
OTHERWISE...TEMPS ARE FCST TO BE ABOVE NORMAL THIS PERIOD WITH
ONLY MINOR TWEAKS MADE.
&&
.LONG TERM...
OVERALL LARGE SCALE PATTERN STILL EXPECTED TO BECOME MORE AMPLIFIED
THROUGH THE LONG TERM WITH BRIEF ARCTIC INTRUSION STILL EXPECTED
LATTER HALF OF WEEKEND INTO NEXT WEEK. MEDIUM RANGE MODELS REMAIN IN
GOOD AGREEMENT ON LARGE SCALE WITH DIFFERENCES CONTINUING IN THE
DETAILS. CR ALLBLEND LOADED AND COLLABORATED SOME TWEAKS TO TEMPS
AND POPS.
A QUIET START EXPECTED ON SATURDAY WITH WARM AIR ADVECTION AHEAD OF
FIRST COLD FRONT AND TEMPERATURES RISING WELL ABOVE NORMAL FOR LATE
DECEMBER. SHOULD SEE 40S ACROSS ENTIRE AREA FOR HIGHS WITH 50S NOT
OUT OF QUESTION SOUTH AND WEST. WARM AIR ADVECTION CONTINUES FIRST
HALF OF SATURDAY NIGHT WITH TEMPS STEADY OR SLOWLY RISING UNTIL
INITIAL FRONTAL PASSAGE LATE. HAVE TRIED TO DETAIL THIS SCENARIO IN
HOURLY GRIDS WITH STEADY TEMPS THROUGH 06Z THEN A SLOW FALL TOWARD
12Z.
DETAIL DIFFERENCES AND COMPLICATIONS IN FORECAST BEGIN IN THIS
SATURDAY NIGHT INTO SUNDAY TIME FRAME WITH STRENGTH AND TIMING OF
COLD AIR ADVECTION AND ANY ASSOCIATED PCPN. 850MB TEMPS BEGIN TO FALL
AFTER 06Z SUNDAY WITH 1000-850MB THICKNESSES FOLLOWING. MODELS
SHOWING LITTLE IN WAY OF PCPN WITH THIS FRONT GIVEN POSITIVELY
TILTED UPPER SYSTEM AND NO STRONG MOISTURE SURGE AHEAD OF IT.
DEEPENING SURFACE LOW REMAINS WELL NORTH OF AREA WITH ONLY SUBTLE
INDICATIONS OF SECONDARY LOW DEVELOPMENT ALONG FRONT BY A FEW
MODELS. HAVE THEREFORE ALLOWED LOW CHANCE POPS TO RIDE SAT NIGHT AND
SUNDAY MORNING. SUNDAY BEGINNING TO LOOK DRY IN WAKE OF INITIAL COLD
FRONT WITH SOME SUNSHINE EVEN POSSIBLE IN DRY SLOT BEFORE SECONDARY
ARCTIC FRONT LATER IN THE DAY. IF THIS OCCURS...FALLING TEMPS EARLY
IN THE MORNING MAY BECOME STEADY OR EVEN RISE A FEW DEGREES BEFORE
SECONDARY FRONT BRINGS MUCH COLDER AIR IN DURING THE AFTERNOON.
FOR NOW HAVE CHOSEN TO GO WITH SLOWLY FALLING TEMPS DURING THE DAY
GIVEN TEMPS LOOK TO FALL IN THE AFTERNOON REGARDLESS.
WITH ARCTIC INTRUSION SUNDAY NIGHT WILL SEE BEST LAKE EFFECT SNOW
POTENTIAL OF THE SEASON AS DELTA T VALUES CLIMB WITH SURFACE TO
850MB WELL INTO LOWER 20S. SURFACE TO 700MB DELTA T VALUES REACH
CRITICAL 30C THRESHOLD WHICH IS A GOOD INDICATOR OF HEAVY SNOW
POTENTIAL. LIMITING FACTOR CONTINUES TO BE MOISTURE PROFILES BUT
MEDIUM RANGE MODELS ARE SHOWING SOME DECENT SYNOPTIC MOISTURE LATE
SUNDAY NIGHT THROUGH MONDAY WHICH WOULD SUPPORT A PERIOD OF HEAVY
LAKE EFFECT SNOW BANDS. NORTHWEST FLOW AND WIND FIELD SUGGEST
MULTI-BANDED EVENT WHICH MAKES PINNING DOWN AMOUNTS AND LOCATIONS
DIFFICULT AT THIS TIME PROJECTION. HAVE BUMPED NW FETCH FAVORED
AREAS INTO LIKELY CATEGORY FOR NOW. HEADLINES POSSIBLE LATER THIS
WEEKEND INTO EARLY NEXT WEEK AS MOISTURE PROFILES BECOME BETTER
DEFINED BY HIGHER RESOLUTION MODELS.
&&
.AVIATION... / 06Z TAFS /
WARM FRONT ASSOCIATED WITH AN APPROACHING SHORTWAVE TROUGH ACROSS
THE UPPER MIDWEST WILL MIX NEWD THROUGH THE FA THIS MORNING
ALLOWING WINDS TO VEER AND GUSTY BY LATE MORNING/AFTN. UPPER MIDWEST
RADAR MOSAIC AND SFC OBS SHOW A NARROW BAND OF LIGHT RAIN IN AREA
OF STRONG ISENTROPIC UPGLIDE ALONG WARM FRONT. EXPECT THIS FORCING
AND SATURATION TO PROPAGATE THROUGH THE LOCAL AREA LATER THIS
MORNING. 00Z MODEL SOUNDINGS CONTINUE TO SUPPORT PCPN MAINLY IN
THE LIQUID FORM...WITH A PERIOD OF -FZRA/FZDZ POSSIBLE AT SBN
BEFORE SFC TEMPS WARM ABOVE FREEZING BY 14/15Z. LESSER CHANCES OF
PCPN AT FWA SO CONTINUED WITH PROB30 MENTION HERE. ALSO OPTED FOR
-RA/DZ WORDING IN PROB30 INSTEAD OF FZDZ AS SFC TEMPS LOOK TO WARM
JUST ABOVE FREEZING BY THE TIME FORCING/TOP DOWN SATURATION WORKS
IN. OTHERWISE...CIGS WILL LIKELY LOWER TO MVFR FOR A TIME ALONG
THE AFOREMENTIONED FRONTAL BOUNDARY WITH IMPROVED MIXING IN ITS
WAKE SUPPORTING VFR CIGS BY THIS AFTN/EVE.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 11 PM EST THIS
EVENING FOR LMZ043.
SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 5 PM EST THIS
AFTERNOON FOR LMZ046.
&&
$$
SHORT TERM...STEINWEDEL
LONG TERM...LASHLEY
AVIATION...STEINWEDEL
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1222 AM EST THU DEC 29 2011
.AVIATION... / 06Z TAFS /
WARM FRONT ASSOCIATED WITH AN APPROACHING SHORTWAVE TROUGH ACROSS
THE UPPER MIDWEST WILL MIX NEWD THROUGH THE FA THIS MORNING
ALLOWING WINDS TO VEER AND GUSTY BY LATE MORNING/AFTN. UPPER MIDWEST
RADAR MOSAIC AND SFC OBS SHOW A NARROW BAND OF LIGHT RAIN IN AREA
OF STRONG ISENTROPIC UPGLIDE ALONG WARM FRONT. EXPECT THIS FORCING
AND SATURATION TO PROPAGATE THROUGH THE LOCAL AREA LATER THIS
MORNING. 00Z MODEL SOUNDINGS CONTINUE TO SUPPORT PCPN MAINLY IN
THE LIQUID FORM...WITH A PERIOD OF -FZRA/FZDZ POSSIBLE AT SBN
BEFORE SFC TEMPS WARM ABOVE FREEZING BY 14/15Z. LESSER CHANCES OF
PCPN AT FWA SO CONTINUED WITH PROB30 MENTION HERE. ALSO OPTED FOR
-RA/DZ WORDING IN PROB30 INSTEAD OF FZDZ AS SFC TEMPS LOOK TO WARM
JUST ABOVE FREEZING BY THE TIME FORCING/TOP DOWN SATURATION WORKS
IN. OTHERWISE...CIGS WILL LIKELY LOWER TO MVFR FOR A TIME ALONG
THE AFOREMENTIONED FRONTAL BOUNDARY WITH IMPROVED MIXING IN ITS
WAKE SUPPORTING VFR CIGS BY THIS AFTN/EVE.
&&
.PREV DISCUSSION... /ISSUED 730 PM EST WED DEC 28 2011/
UPDATE...
NEXT CLIPPER SYSTEM LOOKS TO IMPACT THE AREA VERY LATE TONIGHT
INTO THURSDAY MORNING. STRENGTHENING WESTERLY LOW LEVEL FLOW LATER
TONIGHT IN ADVANCE OF THIS FEATURE WILL BEGIN TO ADVECT WARMER LOW
LEVEL AIR EASTWARD. POSITIVE LOW LEVEL THEATE ADVECTION ALREADY
UNDERWAY ACROSS THE LOCAL AREA EARLY THIS EVENING...ALTHOUGH AIR MASS
INITIALLY OVER THE AREA IS QUITE DRY AND MOISTURE AVAILABILITY
REMAINS THE PRIMARY LIMITING FACTOR TO PRECIPITATION AMOUNTS WITH
THIS CLIPPER. ONLY CHANGE THAT WILL BE MADE TO PREVIOUS FORECAST
WILL BE TO ADD SLIGHT CHANCE MENTION OF LIGHT FREEZING RAIN IN THE
11Z TO 15Z TIMEFRAME. DESPITE WARM ADVECTION OVERNIGHT...SHOULD
MAINTAIN ENOUGH OF A SHALLOW COLD LAYER TO PROVIDE A BRIEF WINDOW
OF SOME LIGHT FREEZING PRECIPITATION. LINGERING SNOWCOVER ACROSS
PORTIONS OF THE AREA MAY ALSO AID IN KEEPING LOW LEVEL TEMPS AT OR
BELOW FREEZING FOR A LONGER DURATION EARLY THURSDAY MORNING. SOME
LOWER CONFIDENCE STILL EXISTS HOWEVER...WITH SOME CONCERNS THAT
MOISTURE AVAILABILITY CONCERNS COULD BE MANIFESTED IN PROFILES TOO
DRY FOR PRECIP WHILE A THERMODYANAMIC PROFILE SUPPORTIVE OF FREEZING
RAIN EXISTS. GIVEN THIS LOWER CONFIDENCE AND EXPECTED LIGHT PRECIP
AMOUNTS WILL NOT BE ISSUING ANY HEADLINES BUT WILL LIKELY ISSUE AN
SPS ADDRESSING THE CHANCE OF A BRIEF PERIOD OF LIGHT FREEZING RAIN
DURING THIS PERIOD. NAM/RUC ISENTROPIC ANALYSES STILL GENERALLY
SUPPORTIVE OF PREVIOUS FORECAST IN AREAS OF HIGHEST CHANCE POPS
ACROSS THE NORTHERN THIRD OF THE AREA...AND ALSO EXTENDING ACROSS
MUCH OF NORTHWEST OHIO THURSDAY MORNING. UPDATED FORECAST WILL BE
SENT OVER THE NEXT HOUR TO ADD THIS SLIGHT CHANCE LIGHT FREEZING
RAIN MENTION.
PREV DISCUSSION... /ISSUED 425 PM EST WED DEC 28 2011/
SHORT TERM...
TONIGHT THROUGH THURSDAY NIGHT
PAIR OF WEAK CLIPPER SYSTEMS TO IMPACT THE AREA IN THE SHORT TERM.
WATER VAPOR IMAGERY AND LATEST RUC ANALYSIS DEPICTING LEAD SHORT
WAVE OVER SOUTHERN MANITOBA AND MOVING INTO WESTERN ONTARIO. THIS
FEATURE EXPECTED TO WEAKEN/SHEAR OUT IN FAST MOVING NW FLOW PATTERN
AS IT DROPS DOWN INTO THE NORTHERN GREAT LAKES TONIGHT/THU AM.
RESULT SHOULD BE BETTER CHANCES FOR PRECIP TO REMAIN NORTH OF THE
AREA WHERE BETTER FORCING AND MOISTURE WILL BE PRESENT...BUT CLOSE
ENOUGH TO MAINTAIN SMALL CHANCE POPS FOR NORTHERN TWO THIRDS OF CWA.
MODELS INDICATING DECENT SFC/LOW LEVEL RESPONSE WITH THIS FIRST
SHORT WAVE RESULTING IN GOOD WAA IN ADVANCE OF THIS SYSTEM WHICH
WILL HAVE TEMPS SLOWLY RISING AFTER MIDNIGHT TONIGHT AND ALSO BRING
PRECIP TYPE INTO QUESTION. FCST SOUNDINGS SHOWING DECENT ELEVATED
WARM LAYER AND MORE FAVORABLE PROFILES IN SUPPORT OF LIQUID
PRECIP...AND WHILE 12Z SOUNDINGS FROM KOAX AND KSGF LEND CREDENCE TO
THIS SCENARIO...STILL NOT CONVINCED THAT MUCH LOW LEVEL WARMING WILL
BE REALIZED WITH FAST MOVING SYSTEM SO WILL KEEP WITH RA/SN MIX IN
WX GRIDS ATTM. 140KT JET COMING ONSHORE IN PACIFIC NW THIS MORNING
WILL DRIVE SECOND SHORT WAVE INTO THE AREA QUICKLY BEHIND THE FIRST
THURSDAY NIGHT. THIS WAVE WILL DIG FURTHER SOUTH AND BRING BETTER
FORCING AND MOISTURE INTO THE FORECAST AREA...AS CURRENTLY REFLECTED
IN GRIDS WITH LOW TO HIGH CHANCE POPS FROM EAST TO WEST ACROSS THE
CWA. STILL LIKE THE NOTION OF A SMALL WINDOW OF DRY WX BETWEEN THESE
TWO SYSTEMS SO WILL STAY WITH DRY FCST 00-06Z FRI. WITH RELATIVELY
WARMER AIR IN PLACE...WILL TREND WX GRIDS TOWARD LIQUID PRECIP WITH
ALL RAIN IN THE SOUTHERN TIER BUT STAY WITH MIX ELSEWHERE GIVEN
NOCTURNAL TIMING. ABOVE NORMAL TEMPS THROUGH THE PERIOD AND GUIDANCE
REASONABLE IN HANDLING THIS.
LONG TERM...
FRIDAY THROUGH WEDNESDAY
AN UPPER LEVEL DISTURBANCE WILL TRACK SOUTHEASTWARD FROM SOUTHERN
ALBERTA/SASKATCHEWAN THURSDAY MORNING INTO THE MIDWEST BY FRIDAY
MORNING. MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT WITH THE TRACK
OF THE WAVE AND THE ATTENDANT SURFACE LOW...HOWEVER MINOR TIMING
DIFFERENCES EXIST. WENT AHEAD AND BUMPED POPS UP TO LIKELY ACROSS
THE NORTHERN HALF OF THE CWA FRIDAY MORNING...ALONG THE PREFERRED
TRACK OF THE SURFACE LOW. PRECIPITATION TYPE CONCERNS REMAIN AN
ISSUE WITH THIS SYSTEM. THERMAL PROFILES PER MODELS SOUNDINGS
SUGGEST MOSTLY RAIN WITH THIS SYSTEM THROUGH THE DAY FRIDAY...WITH
COLDER AIR ARRIVING LATE AFTERNOON...INTRODUCING A MIX AND EVENTUAL
CHANGEOVER TO SNOW AND PRECIPITATION TAPERS OFF. HOWEVER...GIVEN THE
TIMING DIFFERENCES BETWEEN MODELS....AND SLIGHT MODEL DIFFERENCES
WITH THE TRACK OF THE SYSTEM...PREFERRED TO LEAVE A RAIN/SNOW
MENTION FOR FRIDAY ACROSS THE NORTH AND FRIDAY NIGHT EVERYWHERE.
WILL DEFER REFINING OF P-TYPE TO NEXT FORECAST CYCLE AND HOPEFULLY
MORE CONSISTENT MODEL SOLUTIONS. NO MAJOR CHANGES TO TEMPERATURES
FRIDAY AND FRIDAY NIGHT.
SYSTEM EXITS THE REGION BY SATURDAY MORNING...AND HIGH PRESSURE
BUILDS INTO THE REGION FROM THE SOUTHWEST. CONDITIONS WILL BE DRY
THROUGH THE DAY SATURDAY...BEFORE A SIGNIFICANT PATTERN CHANGE
ARRIVES ACROSS THE REGION.
UPPER LEVEL TROF WILL DIG SOUTHEAST FROM CANADA INTO THE EASTERN
CONUS SUNDAY INTO EARLY NEXT WEEK...AND ALONG WITH IT A POLAR AIR
MASS...WITH MODEL H85 TEMPS APPROACHING -20C BY TUESDAY ACROSS THE
REGION. SFC LOW PRESSURE WILL MOVE ACROSS THE NORTHERN TIER INTO THE
GREAT LAKES REGION BY BY SUNDAY. MODELS DIFFER WITH THE EXACT TRACK
OF THE LOW...WITH THE GFS SUPPORTING A FASTER MORE SOUTHERLY
TRACK...AND THE ECMWF A BIT SLOWER WITH A MORE NORTHERLY TRACK.
CONSEQUENTLY...THE GFS SUPPORTS STRONGER FORCING ACROSS THE REGION
SATURDAY NIGHT INTO SUNDAY...WHILE THE ECMWF SUPPORTS WEAKER FORCING
MOVING INTO THE AREA DURING THE DAY SUNDAY. ALLBLEND PROCEDURE
INTRODUCED SLIGHT CHANCE POPS ON SATURDAY NIGHT...WHICH HAVE BEEN
RETAINED FOR COLLABORATIVE PURPOSES. FEEL THAT THE GFS IS SLIGHTLY
TO FAST WITH THE TRACK OF THE SYSTEM AND BEST PRECIP CHANCES WILL BE
DURING THE DAY SUNDAY.
COLD AIR WILL THEN FILTER INTO THE REGION BEHIND THE FRONT...WHICH
WILL BE THE CATALYST FOR LAKE EFFECT SNOW LATE SUNDAY THROUGH
TUESDAY ACROSS THE AREA. MODELS ARE IN DECENT AGREEMENT OF A NW TO
NORTHERLY FETCH AND ADEQUATE MOISTURE PROFILE...WITH LAKE SFC TO H85
DELTA TS IN EXCESS OF 20C...AND LAKE SFC TO H7 DELTA TS IN THE MID
TO UPPER 20C RANGE. WENT AHEAD AND RAISED POPS SUNDAY NIGHT INTO
TUESDAY TO HIGH CHANCE ACROSS LAKE EFFECT PREFERRED AREAS. NO MAJOR
CHANGES TO TEMPERATURES...AS THE ALLBLEND SOLUTIONS HAVE CAUGHT ON
TO COLDER TEMPERATURES WITH THE ARRIVAL OF THE POLAR AIR MASS.&&
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 11 PM EST THIS
EVENING FOR LMZ043.
SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 5 PM EST THIS
AFTERNOON FOR LMZ046.
&&
$$
SHORT TERM...LOGSDON
LONG TERM...NG
UPDATE...MARSILI
AVIATION...STEINWEDEL
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
730 PM EST WED DEC 28 2011
.UPDATE...
NEXT CLIPPER SYSTEM LOOKS TO IMPACT THE AREA VERY LATE TONIGHT
INTO THURSDAY MORNING. STRENGTHENING WESTERLY LOW LEVEL FLOW LATER
TONIGHT IN ADVANCE OF THIS FEATURE WILL BEGIN TO ADVECT WARMER LOW
LEVEL AIR EASTWARD. POSITIVE LOW LEVEL THEATE ADVECTION ALREADY
UNDERWAY ACROSS THE LOCAL AREA EARLY THIS EVENING...ALTHOUGH AIR MASS
INITIALLY OVER THE AREA IS QUITE DRY AND MOISTURE AVAILABILITY
REMAINS THE PRIMARY LIMITING FACTOR TO PRECIPITATION AMOUNTS WITH
THIS CLIPPER. ONLY CHANGE THAT WILL BE MADE TO PREVIOUS FORECAST
WILL BE TO ADD SLIGHT CHANCE MENTION OF LIGHT FREEZING RAIN IN THE
11Z TO 15Z TIMEFRAME. DESPITE WARM ADVECTION OVERNIGHT...SHOULD
MAINTAIN ENOUGH OF A SHALLOW COLD LAYER TO PROVIDE A BRIEF WINDOW
OF SOME LIGHT FREEZING PRECIPITATION. LINGERING SNOWCOVER ACROSS
PORTIONS OF THE AREA MAY ALSO AID IN KEEPING LOW LEVEL TEMPS AT OR
BELOW FREEZING FOR A LONGER DURATION EARLY THURSDAY MORNING. SOME
LOWER CONFIDENCE STILL EXISTS HOWEVER...WITH SOME CONCERNS THAT
MOISTURE AVAILABILITY CONCERNS COULD BE MANIFESTED IN PROFILES TOO
DRY FOR PRECIP WHILE A THERMODYANAMIC PROFILE SUPPORTIVE OF FREEZING
RAIN EXISTS. GIVEN THIS LOWER CONFIDENCE AND EXPECTED LIGHT PRECIP
AMOUNTS WILL NOT BE ISSUING ANY HEADLINES BUT WILL LIKELY ISSUE AN
SPS ADDRESSING THE CHANCE OF A BRIEF PERIOD OF LIGHT FREEZING RAIN
DURING THIS PERIOD. NAM/RUC ISENTROPIC ANALYSES STILL GENERALLY
SUPPORTIVE OF PREVIOUS FORECAST IN AREAS OF HIGHEST CHANCE POPS
ACROSS THE NORTHERN THIRD OF THE AREA...AND ALSO EXTENDING ACROSS
MUCH OF NORTHWEST OHIO THURSDAY MORNING. UPDATED FORECAST WILL BE
SENT OVER THE NEXT HOUR TO ADD THIS SLIGHT CHANCE LIGHT FREEZING
RAIN MENTION.
&&
.AVIATION...
00Z TAFS...APPROACHING CLIPPER SYSTEM AND PRECIPITATION TYPE
CONCERNS FOR THURSDAY MORNING WILL BE THE MAIN FORECAST CONCERN.
REGIONAL RADAR MOSAIC INDICATING AN AREA OF PRECIPITATION FROM
NORTH CENTRAL NORTH DAKOTA INTO EASTERN SOUTH DAKOTA. A FAST
MOVING SHORT WAVE WILL REACH THE WESTERN GREAT LAKES REGION
THURSDAY MORNING...EVENTUALLY ALLOWING THIS LIGHT PRECIPITATION TO
AFFECT AREAS OF MAINLY FAR NORTHERN INDIANA INTO NORTHWEST OHIO.
WARM AIR ADVECTING INTO NORTHERN INDIANA TONIGHT IN ADVANCE OF
THIS SYSTEM COUPLED WITH THE POSSIBILITY OF SHALLOW SUBFREEZING
AIR AT THE SURFACE DOES LEND SOME CONCERN FOR A VERY BRIEF WINDOW OF
LIGHT FREEZING RAIN POTENTIAL SOMETIME IN THE 11Z-15Z TIMEFRAME.
HOWEVER...WITH AN INITIALLY VERY DRY AIR MASS CONFIDENCE IS LOW
THAT PRECIPITATION WILL OCCUR DURING A TIME WHEN THE THERMAL
PROFILES WOULD SUPPORT FREEZING PRECIP. THUS...HAVE KEPT THIS
MENTION OUT OF THE TAFS AT THIS TIME AND ADDED A PROB30 -RA
MENTION FOR THE MID TO LATE MORNING HOURS AS BOUNDARY LAYER TEMPS
WARM ABOVE FREEZING. A FAIRLY STRONG SFC LOW WILL WORK ACROSS
CENTRAL LAKE MICHIGAN THURSDAY MORNING...ALLOWING FOR SFC WIND
GUSTS TO STRENGTHEN LATE MORNING OR TOWARD MIDDAY WITH GUSTS TO
20 TO 25 KNOTS EXPECTED DURING THE AFTERNOON. DID INCLUDE SOME
HIGHER END MVFR CIGS OF DURING THE TIME CORRESPONDING TO THE
STRONGEST FORCING IN THE MORNING HOURS.
&&
.PREV DISCUSSION... /ISSUED 425 PM EST WED DEC 28 2011/
SHORT TERM...
TONIGHT THROUGH THURSDAY NIGHT
PAIR OF WEAK CLIPPER SYSTEMS TO IMPACT THE AREA IN THE SHORT TERM.
WATER VAPOR IMAGERY AND LATEST RUC ANALYSIS DEPICTING LEAD SHORT
WAVE OVER SOUTHERN MANITOBA AND MOVING INTO WESTERN ONTARIO. THIS
FEATURE EXPECTED TO WEAKEN/SHEAR OUT IN FAST MOVING NW FLOW PATTERN
AS IT DROPS DOWN INTO THE NORTHERN GREAT LAKES TONIGHT/THU AM.
RESULT SHOULD BE BETTER CHANCES FOR PRECIP TO REMAIN NORTH OF THE
AREA WHERE BETTER FORCING AND MOISTURE WILL BE PRESENT...BUT CLOSE
ENOUGH TO MAINTAIN SMALL CHANCE POPS FOR NORTHERN TWO THIRDS OF CWA.
MODELS INDICATING DECENT SFC/LOW LEVEL RESPONSE WITH THIS FIRST
SHORT WAVE RESULTING IN GOOD WAA IN ADVANCE OF THIS SYSTEM WHICH
WILL HAVE TEMPS SLOWLY RISING AFTER MIDNIGHT TONIGHT AND ALSO BRING
PRECIP TYPE INTO QUESTION. FCST SOUNDINGS SHOWING DECENT ELEVATED
WARM LAYER AND MORE FAVORABLE PROFILES IN SUPPORT OF LIQUID
PRECIP...AND WHILE 12Z SOUNDINGS FROM KOAX AND KSGF LEND CREDENCE TO
THIS SCENARIO...STILL NOT CONVINCED THAT MUCH LOW LEVEL WARMING WILL
BE REALIZED WITH FAST MOVING SYSTEM SO WILL KEEP WITH RA/SN MIX IN
WX GRIDS ATTM. 140KT JET COMING ONSHORE IN PACIFIC NW THIS MORNING
WILL DRIVE SECOND SHORT WAVE INTO THE AREA QUICKLY BEHIND THE FIRST
THURSDAY NIGHT. THIS WAVE WILL DIG FURTHER SOUTH AND BRING BETTER
FORCING AND MOISTURE INTO THE FORECAST AREA...AS CURRENTLY REFLECTED
IN GRIDS WITH LOW TO HIGH CHANCE POPS FROM EAST TO WEST ACROSS THE
CWA. STILL LIKE THE NOTION OF A SMALL WINDOW OF DRY WX BETWEEN THESE
TWO SYSTEMS SO WILL STAY WITH DRY FCST 00-06Z FRI. WITH RELATIVELY
WARMER AIR IN PLACE...WILL TREND WX GRIDS TOWARD LIQUID PRECIP WITH
ALL RAIN IN THE SOUTHERN TIER BUT STAY WITH MIX ELSEWHERE GIVEN
NOCTURNAL TIMING. ABOVE NORMAL TEMPS THROUGH THE PERIOD AND GUIDANCE
REASONABLE IN HANDLING THIS.
LONG TERM...
FRIDAY THROUGH WEDNESDAY
AN UPPER LEVEL DISTURBANCE WILL TRACK SOUTHEASTWARD FROM SOUTHERN
ALBERTA/SASKATCHEWAN THURSDAY MORNING INTO THE MIDWEST BY FRIDAY
MORNING. MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT WITH THE TRACK
OF THE WAVE AND THE ATTENDANT SURFACE LOW...HOWEVER MINOR TIMING
DIFFERENCES EXIST. WENT AHEAD AND BUMPED POPS UP TO LIKELY ACROSS
THE NORTHERN HALF OF THE CWA FRIDAY MORNING...ALONG THE PREFERRED
TRACK OF THE SURFACE LOW. PRECIPITATION TYPE CONCERNS REMAIN AN
ISSUE WITH THIS SYSTEM. THERMAL PROFILES PER MODELS SOUNDINGS
SUGGEST MOSTLY RAIN WITH THIS SYSTEM THROUGH THE DAY FRIDAY...WITH
COLDER AIR ARRIVING LATE AFTERNOON...INTRODUCING A MIX AND EVENTUAL
CHANGEOVER TO SNOW AND PRECIPITATION TAPERS OFF. HOWEVER...GIVEN THE
TIMING DIFFERENCES BETWEEN MODELS....AND SLIGHT MODEL DIFFERENCES
WITH THE TRACK OF THE SYSTEM...PREFERRED TO LEAVE A RAIN/SNOW
MENTION FOR FRIDAY ACROSS THE NORTH AND FRIDAY NIGHT EVERYWHERE.
WILL DEFER REFINING OF P-TYPE TO NEXT FORECAST CYCLE AND HOPEFULLY
MORE CONSISTENT MODEL SOLUTIONS. NO MAJOR CHANGES TO TEMPERATURES
FRIDAY AND FRIDAY NIGHT.
SYSTEM EXITS THE REGION BY SATURDAY MORNING...AND HIGH PRESSURE
BUILDS INTO THE REGION FROM THE SOUTHWEST. CONDITIONS WILL BE DRY
THROUGH THE DAY SATURDAY...BEFORE A SIGNIFICANT PATTERN CHANGE
ARRIVES ACROSS THE REGION.
UPPER LEVEL TROF WILL DIG SOUTHEAST FROM CANADA INTO THE EASTERN
CONUS SUNDAY INTO EARLY NEXT WEEK...AND ALONG WITH IT A POLAR AIR
MASS...WITH MODEL H85 TEMPS APPROACHING -20C BY TUESDAY ACROSS THE
REGION. SFC LOW PRESSURE WILL MOVE ACROSS THE NORTHERN TIER INTO THE
GREAT LAKES REGION BY BY SUNDAY. MODELS DIFFER WITH THE EXACT TRACK
OF THE LOW...WITH THE GFS SUPPORTING A FASTER MORE SOUTHERLY
TRACK...AND THE ECMWF A BIT SLOWER WITH A MORE NORTHERLY TRACK.
CONSEQUENTLY...THE GFS SUPPORTS STRONGER FORCING ACROSS THE REGION
SATURDAY NIGHT INTO SUNDAY...WHILE THE ECMWF SUPPORTS WEAKER FORCING
MOVING INTO THE AREA DURING THE DAY SUNDAY. ALLBLEND PROCEDURE
INTRODUCED SLIGHT CHANCE POPS ON SATURDAY NIGHT...WHICH HAVE BEEN
RETAINED FOR COLLABORATIVE PURPOSES. FEEL THAT THE GFS IS SLIGHTLY
TO FAST WITH THE TRACK OF THE SYSTEM AND BEST PRECIP CHANCES WILL BE
DURING THE DAY SUNDAY.
COLD AIR WILL THEN FILTER INTO THE REGION BEHIND THE FRONT...WHICH
WILL BE THE CATALYST FOR LAKE EFFECT SNOW LATE SUNDAY THROUGH
TUESDAY ACROSS THE AREA. MODELS ARE IN DECENT AGREEMENT OF A NW TO
NORTHERLY FETCH AND ADEQUATE MOISTURE PROFILE...WITH LAKE SFC TO H85
DELTA TS IN EXCESS OF 20C...AND LAKE SFC TO H7 DELTA TS IN THE MID
TO UPPER 20C RANGE. WENT AHEAD AND RAISED POPS SUNDAY NIGHT INTO
TUESDAY TO HIGH CHANCE ACROSS LAKE EFFECT PREFERRED AREAS. NO MAJOR
CHANGES TO TEMPERATURES...AS THE ALLBLEND SOLUTIONS HAVE CAUGHT ON
TO COLDER TEMPERATURES WITH THE ARRIVAL OF THE POLAR AIR MASS.&&
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...LOGSDON
LONG TERM...NG
AVIATION...MARSILI
UPDATE...MARSILI
AREA FORECAST DISCUSSION
NWS GOODLAND KS
219 AM MST THU DEC 29 2011
.SHORT TERM (TODAY-SATURDAY)...
218 AM MST THU DEC 29 2011
WINDS AND TEMPERATURES ARE THE CHALLENGES WITH THE SHORT TERM PART
OF THE FORECAST.
FAST MOVING SHORT WAVE TROUGH WILL MOVE ACROSS THE NEBRASKA PANHANDLE
AFTER 18Z TODAY. ONLY EXPECT TO SEE INCREASING CIRRUS CLOUDS WITH
THE FEATURE AS BEST DIFFERENTIAL CYCLONIC VORTICITY ADVECTION WILL
BE NORTH OF AREA. 850 MB ANALYSIS SHOWED 8 DEGREE CELSIUS TEMPERATURES
FROM KDDC TO KLBF...AND MOST MODELS AGREE THAT TEMPERATURES WILL
REACH 12-14 DEGREES CELSIUS BY THIS AFTERNOON. THIS WILL PRODUCE
TEMPERATURES IN THE LOW TO MID 60S...EXCEPT AREAS SOUTH OF
INTERSTATE 70 THAT ARE STILL IMPACTED BY SNOW COVER. MAY NOT HAVE
THE BENEFIT OF FULL SOLAR INSOLATION GIVEN INCREASING HIGH LEVEL
CLOUDS..BY HIGHS TODAY COULD BE CLOSE TO RECORDS. THE RECORD HIGH
AT KITR IS 63 WHICH IS WITHIN REACH. WINDS TODAY ARE PROBLEMATIC.
THERE IS DECENT POTENTIAL FOR MIXING...AND 850 MB WINDS WILL BE
30-40 KNOTS. SURFACE GRADIENT IS NOT IMPRESSIVE...HOWEVER... AND WILL
ONLY MENTION BREEZY CONDITIONS TODAY THOUGH THE NEBRASKA COUNTIES
MAY HAVE HIGHER GUSTS WHERE 850 MB WINDS WILL BE THE STRONGEST.
FIRST SHORT WAVE MOVES EAST TONIGHT...BUT PUSHES COOLER AIR ACROSS
THE FORECAST AREA. TEMPERATURES FRIDAY WILL BE 5-10 DEGREES COOLER.
NEXT SHORTWAVE TROUGH MOVES OVER THE NORTHERN ROCKIES FRIDAY NIGHT.
IT WILL BE STRONGER AND FURTHER SOUTH THAN THE PRIOR FEATURE...BUT
MOISTURE WILL CONTINUE TO BE LIMITED THIS FAR SOUTH. AN ASSOCIATED
COLD FRONT WILL MOVE THROUGH THE AREA SATURDAY. TIMING IS STILL
UNCERTAIN...BUT 18Z SATURDAY AFTERNOON IS A LOGICAL STARTING POINT
FOR FRONTAL PASSAGE AT KGLD. HOWEVER...DEPENDING ON THE TIMING...
TEMPERATURES MAY WARM INTO THE MID 50S...OR NOT EVEN REACH THE 50S.
HAVE TRENDED TEMPERATURES DOWN FOR SATURDAY AFTERNOON...BUT SUBSEQUENT
MODEL RUNS WILL PROVIDE A CLEARER PICTURE ABOUT TEMPERATURES. IT
SEEMS A GIVEN...HOWEVER...THAT WINDS BEHIND THE FRONT WILL BE STRONG.
HAVE REALLY BOOSTED THE FORECASTED WINDS SATURDAY AFTERNOON...AND
WOULD NOT BE SURPRISED TO SEE A WIND HIGHLIGHT EVENTUALLY BE ISSUED.
&&
.LONG TERM (SUNDAY-WEDNESDAY)...
218 AM MST THU DEC 29 2011
SUNDAY THROUGH WEDNESDAY...DID NOT MAKE ANY CHANGES FROM INITIALIZED
GRIDS SINCE THEY LOOK REASONABLE AT THIS TIME. HOWEVER...
DETERMINISTIC AND ENSEMBLE MODEL OUTPUT ARE NOT IN VERY GOOD
AGREEMENT WITH THE MID/UPPER PATTERN...MAINLY FOR THE SUNDAY INTO
TUESDAY TIME PERIOD. ONE THING FOR SURE...NO MATTER WHICH MODEL ONE
USES THE PATTERN IS A DRY ONE...AND GRIDS REFLECT THAT. WHERE THE
DIFFERENCES ALOFT CAUSE PROBLEMS IS WITH THE SURFACE WIND AND
TEMPERATURE FORECASTS.
ON SUNDAY TEMPERATURES WILL BE COOLER THAN SATURDAY DUE TO A COLD
FRONT MOVING THROUGH ON SATURDAY. HOWEVER...DIFFERENCES IN HOW COLD
THE MODELS MAKE IT SHOW UP. CANADIAN IS MUCH COLDER...THE GFS THE
WARMEST AND THE ECMWF SLIGHTLY COLDER THAN THE GFS. DUE TO MODEL
DIFFERENCES AND SNOW FIELD...LEFT CURRENT MAXES ALONE BUT POTENTIAL
IS THERE FOR IT TO BE COOLER. ON MONDAY...RETURN FLOW BEGINS AND
WOULD EXPECT SOME WARMING. HOWEVER THIS FLOW IS COMING OVER
SUBSTANTIAL SNOWFIELD TO OUR SOUTH AND SURFACE HIGH IS NOT THAT FAR
AWAY. POTENTIAL IS THERE FOR IT BEING COOLER THAN WHAT IS IN THERE.
DEPENDING ON WHICH MODEL YOU CHOOSE...THERE LOOKS TO BE ANOTHER COOL
SURGE MOVING THROUGH TUESDAY INTO TUESDAY NIGHT WHICH COULD CAUSE
THE HIGH TEMPERATURES TO BE COOLER THAN THE RATHER MILD/ABOVE NORMAL
TEMPERATURES THAT ARE IN THERE FOR TUESDAY AND WEDNESDAY. ALSO HOW
MUCH OF THE SNOW FIELD REMAINS WILL ALSO BE A FACTOR IN THE WARM UP.
&&
.AVIATION...
1020 PM MST WED DEC 28 2011
FOR THE 06Z TAFS AT KGLD AND KMCK...VFR THROUGH THE PERIOD. WEST
WINDS OF 10-15KTS EXPECTED THROUGH 18Z THEN INCREASING SLIGHTLY WITH
GUSTS 25KTS OR SO AS A SFC TROUGH MOVES THROUGH. STILL SOME
UNCERTAINTY AS TO WHETHER THE STRONGER WINDS ALOFT MIX DOWN AS
LATEST RUC MODEL SHOWING SUSTAINED WINDS AT KGLD AROUND 20-25KTS
WITH HIGHER GUSTS BY 20Z. BY 00Z WINDS BACK OFF WITH SPEEDS
10-15KTS. CLOUDINESS WILL BE LIMITED TO MID AND UPPER LEVELS.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1020 PM MST WED DEC 28 2011
.DISCUSSION...
224 PM MST WED DEC 28 2011
A SERIES OF SHORT WAVE TROUGHS ALOFT...AND THEIR ACCOMPANYING
SURFACE SYSTEMS...ARE FORECAST TO MOVE RAPIDLY SOUTHEAST ACROSS THE
NORTHERN PLAINS THROUGH FRIDAY. PRECIPITATION POTENTIAL FOR US LOOKS
SLIM WITH THESE SYSTEMS GIVEN THEIR LOCATION...SPEED AND AN
OVERALL LACK OF LOW TO MID LEVEL MOISTURE. HOWEVER...THEY WILL
BRING A FLUCTUATION IN SURFACE TEMPERATURES OVER THE NEXT FEW
DAYS.
850 MB TEMPERATURES ARE FORECAST TO CLIMB 3-5 DEGREES C THURSDAY
OVER TODAYS TEMPS DEPENDING ON WHICH MODEL IS VIEWED. GIVEN CURRENT
TEMPERATURES IN THE MIDDLE 50S IN THE SNOW-FREE AREAS...LOWER 60S
SEEM A GOOD BET FOR TOMORROWS HIGHS. TEMPERATURES WILL COOL TO THE
40S AND 50S FRIDAY AS SURFACE WINDS SHIFT BACK TO NORTHWEST AND 850
TEMPS COOL.
THE SNOW COVERED AREAS STILL PRESENT A CHALLENGE FOR TEMPERATURE
FORECASTING... REMAINING SOME 15 DEGREES COLDER THAN BARE GROUND.
WILL CONTINUE THIS COOLER TREND OVER THE SNOW FOR THE NEXT FEW
DAYS BUT WITH DIMINISHING IMPACT AS SNOW COVER DECREASES.
THE STRENGTH OF SURFACE WINDS THURSDAY ARE STILL A BIT UNCERTAIN.
GUIDANCE DIFFERS WITH FORECAST 850 MB WINDS TOMORROW...WITH THE
ECMWF SHOWING SPEEDS OF 15-20 KTS WHILE THE GFS SHOWS 35-40 KTS
ACROSS THE NORTH. FOR NOW HAVE PLACED STRONGEST WINDS IN THE NORTH
THIRD WITH GUSTS TO AROUND 30 MPH BUT THIS MAY NEED TO BE REVISITED.
THE NEXT SIGNIFICANT SYSTEM TO IMPACT THE REGION WILL BE IN THE
SATURDAY-SUNDAY TIME FRAME AS A PROGRESSIVE TROUGH DIGS SOUTHEAST
FROM THE PACIFIC NORTHWEST. GUIDANCE HAS BEEN HIT AND MISS FOR
SPOTTY PRECIPITATION WITH THAT SYSTEM. GIVEN SURFACE HIGH PRESSURE
ACROSS THE TX-OK AREA AHEAD OF THIS TROUGH...MOISTURE WILL AGAIN
BE SPARSE DOWN LOW. ALTHOUGH SOME SPOTTY PRECIP CANT BE RULED
OUT...WILL CONTINUE THE DRY FORECAST.
THE LONGER RANGE GUIDANCE INDICATES UPPER RIDGING WILL RETURN
EARLY NEXT WEEK...CONTINUING THE MILD AND DRY TREND AS WE KICK OFF
THE NEW YEAR.
99
&&
.AVIATION...
1020 PM MST WED DEC 28 2011
FOR THE 06Z TAFS AT KGLD AND KMCK...VFR THROUGH THE PERIOD. WEST
WINDS OF 10-15KTS EXPECTED THROUGH 18Z THEN INCREASING SLIGHTLY WITH
GUSTS 25KTS OR SO AS A SFC TROUGH MOVES THROUGH. STILL SOME
UNCERTAINTY AS TO WHETHER THE STRONGER WINDS ALOFT MIX DOWN AS
LATEST RUC MODEL SHOWING SUSTAINED WINDS AT KGLD AROUND 20-25KTS
WITH HIGHER GUSTS BY 20Z. BY 00Z WINDS BACK OFF WITH SPEEDS
10-15KTS. CLOUDINESS WILL BE LIMITED TO MID AND UPPER LEVELS.
007
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1036 AM MST TUE DEC 27 2011
.UPDATE...
1034 AM MST TUE DEC 27 2011
UPDATED TODAY/S HIGH TEMPS BY RAISING MOST AREAS UPWARD BY A
CATEGORY BASED ON LATEST TRENDS IN THE SFC OBS. NO OTHER CHANGES
WERE NEEDED.
05
&&
.SYNOPSIS...
CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH
PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL
MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE
US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN
THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A
SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST
REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR
AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO
HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD.
JTL
&&
.SHORT TERM (TODAY-THURSDAY)...
228 AM MST TUE DEC 27 2011
TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD.
SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA
TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE
THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF
MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS
SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES
A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND
SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT
OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS
TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT.
WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL
FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY
WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN
TUESDAY.
THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH
THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT
WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH
WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES
THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE
TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE
NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND.
850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH
THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND
NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND
60 ARE NOT OUT OF THE QUESTION.
JTL
.LONG TERM (FRIDAY-MONDAY)...
228 AM MST TUE DEC 27 2011
LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE
TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH
THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR
SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS
LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION
AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE
SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED
TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING
OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN
WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL
BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN
NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO
FINALLY REACH INTO THE 50S THERE BY FRIDAY.
&&
.AVIATION...
1018 AM MST TUE DEC 27 2011
FOR THE 18Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD.
LIGHT WINDS HAVE BACKED TO THE SOUTHWEST AS LOW PRESSURE DEEPENED
TO THE NORTHEAST OF THE TERMINALS. WINDS WILL RETURN TO THE
NORTHWEST OVERNIGHT AS HIGH PRESSURE BUILDS ACROSS THE REGION.
CJS
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1018 AM MST TUE DEC 27 2011
.SYNOPSIS...
CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH
PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL
MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE
US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN
THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A
SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST
REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR
AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO
HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD.
JTL
&&
.SHORT TERM (TODAY-THURSDAY)...
228 AM MST TUE DEC 27 2011
TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD.
SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA
TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE
THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF
MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS
SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES
A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND
SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT
OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS
TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT.
WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL
FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY
WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN
TUESDAY.
THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH
THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT
WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH
WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES
THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE
TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE
NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND.
850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH
THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND
NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND
60 ARE NOT OUT OF THE QUESTION.
JTL
.LONG TERM (FRIDAY-MONDAY)...
228 AM MST TUE DEC 27 2011
LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE
TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH
THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR
SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS
LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION
AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE
SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED
TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING
OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN
WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL
BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN
NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO
FINALLY REACH INTO THE 50S THERE BY FRIDAY.
&&
.AVIATION...
1018 AM MST TUE DEC 27 2011
FOR THE 18Z TAFS...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD.
LIGHT WINDS HAVE BACKED TO THE SOUTHWEST AS LOW PRESSURE DEEPENED
TO THE NORTHEAST OF THE TERMINALS. WINDS WILL RETURN TO THE
NORTHWEST OVERNIGHT AS HIGH PRESSURE BUILDS ACROSS THE REGION.
CJS
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
413 AM MST TUE DEC 27 2011
.SYNOPSIS...
CURRENT SATELLITE IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A HIGH
PRESSURE OVER THE SOUTHWEST CONUS...WITH A SHORT WAVE TROUGH AND MID LEVEL
MOISTURE MOVING AROUND THE NORTHERN PERIPHERY OF THE HIGH ALONG THE
US/CANADIAN BORDER. OVER THE CENTRAL PLAINS A SHORT WAVE TROUGH IN
THE NORTHWEST FLOW WAS PRODUCING A FEW CLOUDS. CLOSER TO HOME A
SURFACE HIGH PRESSURE WAS BUILDING INTO THE TRI-STATE AREA. LATEST
REPORTS OF SNOW DEPTH SHOW 2 TO 10 INCHES STILL ON THE GROUND FOR
AREAS OF CENTRAL AND SOUTHWEST KANSAS...SO AM EXPECTING THIS TO
HAVE A COOLING EFFECT ON TEMPERATURES THROUGH THE PERIOD.
JTL
&&
.SHORT TERM (TODAY-THURSDAY)...
228 AM MST TUE DEC 27 2011
TEMPERATURES WILL BE THE MAIN CONCERN FOR THIS PERIOD.
SURFACE HIGH PRESSURE WILL MOVE ACROSS THE TRI-STATE AREA
TODAY...PRECEDING A SURFACE AND UPPER LEVEL TROUGH THAT WILL MOVE
THROUGH DURING THE EVENING HOURS. MODELS HAVE REDUCED THE AMOUNT OF
MOISTURE AND LIFT WITH THE TROUGH PASSAGE...SO WILL FOLLOW PREVIOUS
SHIFT AND KEEP OUT ANY MENTION OF PRECIPITATION. HIGH TEMPERATURES
A BIT TRICKY DUE TO THE COMBINED EFFECTS OF CLOUD COVER AND
SOUTHERLY WINDS BRINGING IN COOLER AIR FROM THE SNOW FIELD...BUT
OVERALL TEMPERATURES TODAY WILL BE COOLER THAN YESTERDAY. LOWS
TONIGHT WILL BE A FEW DEGREES WARMER THAN LAST NIGHT.
WEDNESDAY MINOR RIPPLES WILL MOVE THROUGH THE UPPER LEVEL
FLOW OVER THE AREA...PRODUCING A FEW CLOUDS AT BEST. WITH WESTERLY
WINDS BRINGING IN WARMER AIR...TEMPERATURES WILL BE WARMER THAN
TUESDAY.
THURSDAY A MINOR SHORT WAVE TROUGH AND SOME MOISTURE MOVE THROUGH
THE UPPER LEVEL FLOW OVER THE AREA. THIS TROUGH WILL HAVE MORE LIFT
WITH IT...BUT WILL HAVE THE BEST LIFT BELOW THE MOISTURE. AS SUCH
WILL LEAVE OUT A MENTION OF ANY PRECIPITATION AS THE TROUGH MOVES
THROUGH. AT THE SURFACE WINDS WILL BECOME NORTHWEST BEHIND THE
TROUGH AND STRENGTHEN SOME...WITH THE STRONGER WINDS OVER THE
NEBRASKA COUNTIES. TEMPERATURES WILL CONTINUE THE WARMING TREND.
850MB TEMPERATURES WARM TO NEAR 10C DURING THE DAY...SO WENT WITH
THE WARMER GUIDANCE SINCE 850MB TEMPERATURES OF 3C YESTERDAY AND
NORTHWEST WINDS PRODUCED HIGHS AROUND 50 DEGREES...SO HIGHS AROUND
60 ARE NOT OUT OF THE QUESTION.
JTL
.LONG TERM (FRIDAY-MONDAY)...
228 AM MST TUE DEC 27 2011
LONG RANGE MODELS CONTINUE TO SHOW WEAK SHORT WAVE
TROUGHS MOVING ACROSS THE HIGH PLAINS IN PSEUDO ZONAL FLOW THROUGH
THE WEEKEND. THE STRONGEST WAVE IS DUE SATURDAY AFTERNOON OR
SATURDAY NIGHT DEPENDING ON MODEL PREFERENCE...BUT MOISTURE APPEARS
LIMITED REGARDLESS SO WILL KEEP FORECASTS DRY. WARM AIR ADVECTION
AND ABOVE NORMAL 500 MB HEIGHTS SUPPORT DECENT WARM/UP BETWEEN THE
SHORT WAVES...ESPECIALLY FRIDAY WHEN 850 MB TEMPERATURES ARE PROGGED
TO REACH BETWEEN 12-14 DEGREES CELSIUS. AGREE WITH SURROUNDING
OFFICES TO INCREASE MAXIMUM TEMPERATURE FORECASTS THAT DAY. EVEN
WITH WARM AIR ADVECTION...TEMPERATURES SOUTH OF INTERSTATE 70 WILL
BE DEPENDENT ON THE AMOUNT OF SNOW PACK MELTING THAT OCCURS BETWEEN
NOW AND FRIDAY. EXPECT ENOUGH MELTING TO ALLOW TEMPERATURES TO
FINALLY REACH INTO THE 50S THERE BY FRIDAY.
&&
.AVIATION...
413 AM MST TUE DEC 27 2011
VFR CONDITIONS WILL CONTINUE THROUGH THE FORECAST PERIOD AT KGLD/KMCK.
SURFACE WINDS AT 10-15 KNOTS WILL GRADUALLY BECOME SOUTHWEST TODAY
BEFORE RETURNING TO THE NORTHWEST AFTER 00Z.
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TODAY THROUGH WEDNESDAY NIGHT/
MODELS ARE IN GOOD AGREEMENT FOR THE PERIOD. A MID/UPPER LEVEL LOW
CROSSING THE LOWER MISSISSIPPI VALLEY ON MONDAY NIGHT WAS BEING
ABSORBED BACK INTO THE PREVAILING WESTERLIES AS A NORTHERN STREAM
TROUGH DROPPED SE TOWARD THE GREAT LAKES. THIS IS RESULTING IN A
DEEPENING SURFACE LOW OVER WEST TN WHICH WILL MOVE NE ACROSS KY. THE
SYSTEM HAS A DEEP MOISTURE TAP...WITH RAIN HAVING OVERSPREAD THE AREA
DURING THE NIGHT. A DRY SLOT WRAPPING NORTHWARD INTO THE SYSTEM WILL
TRY TO MOVE N INTO KY TODAY...BRINGING A DIMINISHING TREND IN RAIN...
ESPECIALLY FOR OUR SOUTHERN AND SOUTHEASTERN COUNTIES LATE THIS
MORNING AND EARLY THIS AFTERNOON. THE TAIL OF THE COMMA HEAD WILL
MOVE EAST ACROSS THE AREA THIS AFTERNOON. IT WILL BRING ANOTHER
INCREASE IN PRECIP...ESPECIALLY FOR OUR NORTHERN AND EASTERN
COUNTIES. THIS PRECIP WILL BE MUCH LIGHTER THAN THAT OF THE MORNING.
WITH COLDER AIR ARRIVING ON THE BACK SIDE OF THE SURFACE LOW...THE
RAIN WILL MIX WITH OR CHANGE TO SNOW FROM NW TO SE DURING THE
LATE AFTERNOON AND EVENING. COLDER AIR ALOFT WILL SUPPORT A SURFACE
CHANGEOVER TEMPERATURE IN THE MID 30S. WILL EXPECT PRECIP TO TAPER
OFF BEFORE TEMPS FALL BELOW FREEZING IN MOST LOCATIONS...PREVENTING
SIGNIFICANT SNOW ACCUMULATIONS. A POSSIBLE EXCEPTION WILL BE
ELEVATIONS ABOVE ABOUT 2000 FEET NEAR THE VA BORDER...AND WILL CALL
FOR A POSSIBILITY OF 1-2 INCHES THERE TONIGHT.
MUCH DRIER AIR SHOULD ARRIVE BY WEDNESDAY MORNING...WITH DRY WEATHER
AND MAINLY CLEAR SKIES FORECAST FOR WEDNESDAY AND WEDNESDAY NIGHT.
HIGH PRESSURE WILL BUILD IN FROM THE WEST ON WEDNESDAY...WITH THE
RIDGE MOVING TO OUR EAST ON WEDNESDAY NIGHT. THE RETURN OF WARM AIR
ADVECTION ON THE BACK SIDE OF THE HIGH ON WEDNESDAY NIGHT WILL
PROMOTE RIDGE/VALLEY LOW TEMPERATURE DIFFERENCES.
.LONG TERM.../THURSDAY THROUGH MONDAY/
THE EXTENDED FORECAST BEGINS ON THURSDAY WITH A PROGRESSIVE PATTERN
IN PLACE AND A BROAD TROUGH OVER THE EASTERN US. THE MAIN CONCERN
COMES IN THE FRIDAY TO SATURDAY PERIOD IN THE FORM OF A COUPLE OF
ALBERTA CLIPPER TYPE LOWS IN NORTHWEST FLOW. BOTH THE GFS AND EURO
ARE AGREEING WITH THE STRENGTH AND POSITIONING OF THE DISTURBANCE
BUT ARE DIVIDED ON THE TIMING. QPF WITH THIS SYSTEM IS MINIMAL AT
BEST...ESPECIALLY WITH ITS CONTINENTAL ORIGIN. AT THIS POINT...SNOW
SEEMS A BIT FAR FETCHED AS BOTH THE EURO AND GFS DO NOT SHOW ANY
SIGNIFICANT COLD AIR IN PLACE AND EVEN ON THE BACK SIDE OF THE
SYSTEM. THEREFORE...WILL LIKELY THROW IN AT LEAST SOME SLIGHT CHANCE
POPS ON FRIDAY AND INTO SATURDAY. THE ONLY OTHER CONCERN IS A
STRONGER WAVE DEVELOPING AND MOVING THROUGH SUNDAY NIGHT AND INTO
MONDAY. THE DIFFERENCES WITH THE EURO AND GFS WITH THIS IS TIMING AS
THE GFS IS 24 HOURS FASTER AND WEAKER THAN THE EURO WITH A SLOWER
AND MORE AMPLIFIED PATTERN. THE EURO DEVELOPS A SHARP TROUGH DIGGING
FROM THE GREAT LAKES TO THE GULF COAST...ALLOWING BITTERLY COLD AIR
INTO THE EAST COAST. FOR NOW THE GFS AND GEM STICK TO THE GFS
ENSEMBLE. WILL STICK TO THE FAST GFS SOLUTION...ESPECIALLY WITH THE
PROGRESSIVE PATTERN IN PLACE DURING THE BEGINNING OF THE EXTENDED.
AFTER INITIALIZATION AND THE 00Z EURO STICKING TO A SLOWER AMPLIFIED
PATTERN FOR THE MON TO TUE TIME FRAME. THE INITIALIZATION DID LEAN
TO THE EURO A BIT BUT THIS IS THE 12Z RUN. WITH THE EURO SHOWING
SOME RUN TO RUN CONSISTENCY WITH THIS AND DEVELOPING A VIGOROUS
COASTAL LOW ON THE MON THROUGH WED TIME FRAME...WILL HAVE TO WATCH
TO SEE IF THE OTHER OPERATIONAL MODELS SHIFT TO THIS SOLUTION. THE
OTHER PIECE OF INFORMATION IS WHAT THE NAO IS SHOWING AND WHILE ITS
ENSEMBLE MEMBERS DO SHOW SOME DIFFERENT SOLUTIONS...A INDICATION OF
A MORE PROGRESSIVE PATTERN AND LESS BLOCKING IS SHOWN THROUGH JAN
1ST...SOME OF THE MEMBERS DO DIP INTO THE NEGATIVE RANGE BY THE 3RD
INDICATING A MORE AMPLIFIED PATTERN. THEREFORE...FOR THE FORECAST
WILL CLEAR OUT POPS BY MONDAY ACCORDING TO THE GFS SOLUTION BUT THE
EURO SOLUTION AS WELL AS THE ENSEMBLES WILL NEED SOME MONITORING.
&&
.AVIATION.../18Z TO 18Z/...UPDATED
SOUTHWEST WINDS WILL BRIEFLY GUST TO 30 TO 35 KNOTS THIS AFTERNOON.
SURFACE LOW PRESSURE HAS MOVED INTO WESTERN OH. A LOW PRESSURE TROF
SWINGING NORTHEAST THROUGH THE AREA IS BRINGING WIDESPREAD RAIN AND
MVFR TO IFR CONDITIONS. GUSTY WINDS ARE OCCURRING IN A SMALL
PRECIPITATION FREE AREA BETWEEN THE PRIMARY RAIN SHIELD AND THE WRAP
AROUND PRECIPITATION NOW MOVING ACROSS CENTRAL KY.
WHILE THE MAIN PRECIPITATION SHIELD IS CURRENTLY EXITING EASTERN
KY...THERE IS CONSIDERABLE WRAP AROUND MOISTURE SO PERIODS OF RAIN
WILL CONTINUE THROUGH THE AFTERNOON WITH GENERALLY MVFR
CEILINGS...AND SOME LOCAL IFR CONDITIONS.
RAIN WILL MIX WITH OR CHANGE TO LIGHT SNOW FOR A TIME TONIGHT AS
COLDER AIR WRAPS AROUND THE EXITING LOW PRESSURE SYSTEM. MVFR CEILINGS
ARE EXPECTED TO PREVAIL LATE TONIGHT INTO WEDNESDAY.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...HAL/SBH
LONG TERM....SHALLENBERGER
AVIATION...SBH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
408 PM EST TUE DEC 27 2011
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING MOSTLY RAIN OVER
THE UPPER OHIO VALLEY REGION TODAY BEFORE PRECIPITATION CHANGES TO
ALL SNOW TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID-
WEEK.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES
THAT ARE SLIGHTLY OFF IN TIMING AND PHASING. THE NORTHERN AND
SLOWER FEATURE IS LOCATED ACROSS LAKE MICHIGAN WITH THE
SOUTHERN BRANCH ALONG ACROSS WESTERN PENNSYLVANIA. AN 850MB CLOSED
LOW IS LOCATED ACROSS NORTH-CENTRAL OHIO. AHEAD OF THIS FEATURE,
A WARM WEDGE OF 850 TEMPS AT 1-3C IS BEGINNING TO EDGE EASTWARD
OUT THE AREA INTO CENTRAL PA WITH 0C TO -2C 850 TEMPS ENCROACHING
EASTERN OHIO. THE WEDGE HAS HELD MOST OF THE DAY WITH RAIN BEING
THE DOMINANT TYPE OF PRECIP ACROSS THE AREA. THERE HAS HOWEVER
BEEN A MIX ALONG THE I-80 CORRIDOR. AT THE SURFACE A 994MB LOW IS
LOCATED ACROSS LAKE ERIE WITH A WIND SHIFT TO NORTHWESTERLY BEHIND
IT. ON THE BACK-SIDE OF THE LOW, A DEFORMATION ZONE WITH MODERATE
SNOW IS WEAKENING AS IT MOVES INTO WESTERN OHIO.
THIS EVENING...THE NORTHERN AND SOUTHERN BRANCHES WILL ATTEMPT
TO PHASE INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO
WESTERN NY. THE 850MB LOW WILL PASS NORTHEAST OF THE AREA, WRAPPING
COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM HINT AT THE RE-
DEVELOPMENT OF A 700MB DEFORMATION ZONE, WHICH WILL BRING A SHOT
OF MODERATE SNOW TO THE AREA THIS EVENING. THE MOST UNCERTAINTY IN
THE FORECAST LIES IN REGARDS TO WHETHER THE DEFORMATION ZONE WILL
CONTINUE TO WEAKEN OR RE-DEVELOP. HAVE SIDED WITH IT RE-
DEVELOPING. AS SURFACE WINDS SHIFT TO NORTHWESTERLY, THE
CHANGEOVER TO SNOW WILL QUICKLY ENSUE. TEMPS WILL REMAIN MID 40S
IN LOCATIONS WEST OF CHESTNUT RIDGE WHERE DOWNSLOPING IS
OCCURRING. OTHERWISE, TEMPS WILL RANGE FROM THE MID 30S ACROSS THE
I-80 CORRIDOR TO THE LOWER 40S ACROSS NORTH-CENTRAL WV. THE
COLDEST AIR REMAINS TRAPPED IN THE VALLEYS OF GARRETT COUNTY,
WHERE TEMPS IN THE LOWER TO MID 30S WILL ALLOW FOR SOME SLEET TO
MIX IN WITH RAIN. WILL CONTINUE TO MONITOR THIS AREA FOR FREEZING
RAIN BEFORE THE TURN OVER TO SNOW.
TONIGHT...THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE
AREA INTO NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR
PRECIPITATION TO QUICKLY TURN OVER TO ALL SNOW. THE 700MB
DEFORMATION ZONE WILL CROSS THE AREA, ALLOWING FOR AN INITIAL
QUICK BURST OF A HALF OF AN INCH TO AN INCH ACROSS MUCH OF THE
AREA. HAVE ISSUED AN SPS TO HIGHLIGHT THIS FEATURE. AFTER THE INITIAL
BURST, A NORTHWESTERLY FLOW WILL ALLOW FOR SNOW SHOWERS ACROSS THE
AREA. UPSLOPING ACROSS THE RIDGES ALONG WITH A SLIGHTLY FASTER
CHANGEOVER FOR AREAS NORTH OF PITTSBURGH WILL ALLOW FOR 2 TO 4
INCHES BY DAWN ON WEDNESDAY. OVERNIGHT LOWS ARE CLOSER TO LAMP
GUIDANCE, RANGING FROM THE MID TO UPPER 20S ACROSS THE AREA. THE
QUICK DROP BELOW FREEZING BY MIDNIGHT, WILL LEAD TO SOME ICY AND
SNOW-COVERED ROADS THROUGH DAWN.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH
DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH
LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH
WILL THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE AROUND 5
DEGREES BELOW NORMAL ON WEDNESDAY AND WEDNESDAY NIGHT AS ARCTIC
AIR SETTLES INTO THE AREA IN THE WAKE OF THE LOW.
THERE IS SOME UNCERTAINTY IN TIMING OF A SERIES OF SHORT WAVES
CROSSING THE AERA THURSDAY INTO FRIDAY. SCHC POPS ARE INTRODUCED
NORTH OF PITTSBURGH ON THURSDAY, INCREASING TO CHANCE THURSDAY
NIGHT, WITH THE BEST CHANCE ON FRIDAY AS A MORE PRONOUNCED TROUGH
AXIS CROSSES THE AREA. MODEL THICKNESSES INDICATE A MIX OF RAIN
AND SNOW SHOWERS FOR THE AREA, SO DO NOT ANTICIPATE ANY
SIGNIFICANT ACCUMULATIONS WITH THE WAVES AS THEY MOVE THROUGH.
TEMPS WILL BE AROUND 5 DEGREES ABOVE SEASONAL NORMALS THURSDAY
INTO FRIDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
FAST MOVING SYSTEMS IN A PROGRESSIVE FLOW WILL BRING TEMPERATURES
AVERAGING CLOSE TO NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS
FOR LATE WEEK INTO THE WEEKEND. STRONGER DISTURBANCE WILL TAP
INTO THE NORTHERN BRANCH OF THE JET STREAM BRINGING PROGRESSIVELY
COLDER AIR INTO THE REGION BY TUESDAY NIGHT.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
IFR CONDITIONS WITH LIFR IN AREAS SOUTH OF PITTSBURGH AS LOW LEVEL
MOISTURE IS TRAPPED UNDER THE INVERSION. LLWS ALL TAF SITES AS H8
LOW LEVEL JET AT MGW OFF THE NAM AT 2PM INDICATES 81KT JET.
WIND SHIFT LINE AND CHANGE OVER TO SNOW IS OVER WESTERN OHIO NOW
IN THE VCNTY OF KDAY. LOW IS DEEPENING RAPIDLY AND THAT WIND SHIFT
AND CHANGE OVER TO SNOW LINE WILL REACH CWA 23Z VCNTY THROUGH 02Z
IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION
TRANSITIONS TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE
EXITING LOW. CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR
LEVELS...BUT IFR VISIBILITY IN SNOW SHOWERS SHOULD CONTINUE.
OUTLOOK...WEDNESDAY THROUGH SUNDAY... CONDITIONS SHOULD GRADUALLY
IMPROVE TO VFR BY LATE WEDNESDAY AS A WEAK SURFACE RIDGE MOVES
EAST. A SERIES OF FAST MOVING WEATHER SYSTEMS WILL THEN CROSS THE
REGION DURING THE LATTER HALF OF THE WEEK WITH PERIODIC
RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR OHZ041.
PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR
PAZ007>009-013-015-016.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR PAZ014-020>023-073>076.
WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
205 PM EST TUE DEC 27 2011
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING MOSTLY RAIN OVER
THE UPPER OHIO VALLEY REGION TODAY BEFORE PRECIPITATION CHANGES TO
ALL SNOW TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID-
WEEK.
&&
.NEAR TERM /THROUGH 8 PM THIS EVENING/...
THE EARLY AFTERNOON UPDATE HAS BEEN ISSUED TO ACCOUNT FOR RECENT
TRENDS IN TEMPS AND TO ADD A MIX OF SLEET WITH RAIN FOR GARRETT
COUNTY IN MARYLAND.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES
THAT ARE TRYING TO PHASE. THE NORTHERN FEATURE IS LOCATED ACROSS THE
UPPER MIDWEST WITH THE SOUTHERN BRANCH ALONG THE OHIO/WEST
VIRGINIA BORDER. AN 850MB CLOSED LOW IS LOCATED ACROSS NORTHWEST
OHIO. AHEAD OF THIS FEATURE, A WARM WEDGE OF 850 TEMPS AT 2-5C HAS
MOVED INTO WESTERN PENNSYLVANIA. THIS HAS ALLOWED PRECIPITATION TO
TURN TO MOSTLY RAIN ACROSS THE AREA. THERE HAS HOWEVER BEEN A MIX
ALONG THE I-80 CORRIDOR. LAPS ANALYSIS INDICATES THE WET BULB ZERO
LINE ACROSS FOREST COUNTY. WET BULBING IN THIS AREA HAS LEAD TO A
MIX OF SNOW AND SLEET BEFORE PRECIPITATION TURNS OVER TO RAIN
BRIEFLY THIS AFTERNOON. AT THE SURFACE A 997MB LOW IS LOCATED NEAR
LIMA, OHIO WITH A WIND SHIFT TO NORTHWESTERLY BEHIND IT. ON THE
BACK-SIDE OF THE LOW, A DEFORMATION ZONE HAS DEVELOPED WITH SOME
AREAS OF MODERATE SNOW IN INDIANA AND WESTERN OHIO.
THIS AFTERNOON...THE NORTHERN AND SOUTHERN BRANCHES WILL ATTEMPT
TO PHASE INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO
NORTHWEST PENNSYLVANIA. THE 850MB LOW WILL PASS NORTHEAST OF THE
AREA, WRAPPING COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM ARE
SHOWING 700MB DEFORMATION ZONE SHIFTING ACROSS THE OHIO VALLEY AND
BRINGING A SHOT OF MODERATE SNOW TO EASTERN OHIO BY THIS EVENING.
AS SURFACE WINDS SHIFT TO NORTHWESTERLY, THE CHANGEOVER TO SNOW
WILL QUICKLY ENSUE. TEMPS WILL REMAIN MID 40S IN LOCATIONS WEST
OF CHESTNUT RIDGE WHERE DOWNSLOPING IS OCCURRING. OTHERWISE, TEMPS
WILL RANGE FROM THE MID 30S ACROSS THE I-80 CORRIDOR TO THE LOWER
40S ACROSS NORTH-CENTRAL WV. THE COLDEST AIR REMAINS TRAPPED IN
THE VALLEYS OF GARRETT COUNTY, WHERE TEMPS IN THE LOWER 30S WILL
ALLOW FOR SOME SLEET TO MIX IN WITH RAIN. WILL CONTINUE TO MONITOR
THIS AREA FOR FREEZING RAIN BEFORE THE TURN OVER TO SNOW.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE AREA INTO
NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR PRECIPITATION TO
QUICKLY TURN OVER TO ALL SNOW. A 700MB DEFORMATION ZONE WILL CROSS
THE AREA, ALLOWING FOR AN INITIAL QUICK BURST OF 1 TO 2 INCHES
ACROSS MUCH OF THE AREA. AFTER THE INITIAL BURST, A NORTHWESTERLY
FLOW WILL ALLOW FOR SNOW SHOWERS ACROSS THE AREA. UPSLOPING ACROSS
THE RIDGES ALONG WITH A SLIGHTLY FASTER CHANGEOVER AND SOME LAKE
ENHANCEMENT FOR AREAS NORTH OF PITTSBURGH WILL ALLOW FOR 2 TO 4
INCHES BY DAWN ON WEDNESDAY. OVERNIGHT LOWS ARE CLOSE TO LAMP
GUIDANCE, RANGING FROM THE MID TO UPPER 20S ACROSS THE AREA. THE
QUICK DROP BELOW FREEZING BY MIDNIGHT, WILL LEAD TO SOME ICY AND
SNOW-COVERED ROADS THROUGH DAWN.
LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH
DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH
LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH WILL
THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE BELOW NORMAL BUT
CONDITIONS SHOULD BE DRY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
FAST MOVING SYSTEMS IN PROGRESSIVE FLOW WILL BRING TEMPERATURES
AVERAGING ABOVE NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS FOR
LATE WEEK INTO THE WEEKEND. LONG TERM PERIOD WAS FORECAST CLOSE TO
HPC PROGS WHICH CONTINUE TO TREND TOWARD THE ECMWF.
&&
.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
IFR CONDITIONS WITH LIFR IN AREAS SOUTH OF PITTSBURGH AS LOW LEVEL
MOISTURE IS TRAPPED UNDER THE INVERSION. LLWS ALL TAF SITES AS H8
LOW LEVEL JET AT MGW OFF THE NAM AT 2PM INDICATES 81KT JET.
WIND SHIFT LINE AND CHANGE OVER TO SNOW IS OVER WESTERN OHIO NOW
IN THE VCNTY OF KDAY. LOW IS DEEPENING RAPIDLY AND THAT WIND SHIFT
AND CHANGE OVER TO SNOW LINE WILL REACH CWA 23Z VCNTY THROUGH 02Z
IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION
TRANSITIONS TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE
EXITING LOW. CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR
LEVELS...BUT IFR VISIBILITY IN SNOW SHOWERS SHOULD CONTINUE.
OUTLOOK...WEDNESDAY THROUGH SUNDAY... CONDITIONS SHOULD GRADUALLY
IMPROVE TO VFR BY LATE WEDNESDAY AS A WEAK SURFACE RIDGE MOVES
EAST. A SERIES OF FAST MOVING WEATHER SYSTEMS WILL THEN CROSS THE
REGION DURING THE LATTER HALF OF THE WEEK WITH PERIODIC
RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR OHZ041.
PA...WINTER WEATHER ADVISORY UNTIL 4 AM EST WEDNESDAY FOR
PAZ007>009-013-015-016.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR PAZ014-020>023-073>076.
WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1127 AM EST TUE DEC 27 2011
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL CROSS THE AREA, SPREADING A WINTRY MIX
OVER THE UPPER OHIO VALLEY REGION TODAY AND THEN ALL SNOW
TONIGHT. HIGH PRESSURE WILL THEN BUILD IN FOR A DRY MID-WEEK.
&&
.NEAR TERM /UNTIL 8 PM THIS EVENING/...
A LATE MORNING UPDATE HAS BEEN ISSUED TO ADD A SNOW/SLEET MIX TO
THE I-80 CORRIDOR AND TO MOVE UP CHANGEOVER TO SNOW BY A FEW HOURS
EARLIER AS TEMPS ARE TRENDING COLDER.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES TWO TROUGH FEATURES
THAT ARE ATTEMPTING TO PHASE. THE NORTHERN FEATURE IS LOCATED
ACROSS THE UPPER MIDWEST WITH THE SOUTHERN BRANCH CROSSING THE
TENNESSEE VALLEY. AN 850MB CLOSED LOW HAS DEVELOPED ACROSS
INDIANA. AHEAD OF THIS FEATURE, A WARM WEDGE OF 850 TEMPS AT 2-4C
HAS MOVED INTO WESTERN PENNSYLVANIA. THIS HAS ALLOWED
PRECIPITATION TO TURN TO MOSTLY RAIN ACROSS THE AREA. THERE HAS
HOWEVER BEEN A MIX NORTH OF PITTSBURGH. LAPS ANALYSIS INDICATES
THE WET BULB ZERO LINE ACROSS THE I-80 CORRIDOR. WET BULBING IN
THIS AREA HAS LEAD TO A MIX OF SNOW AND SLEET BEFORE PRECIPITATION
TURNS OVER TO RAIN BRIEFLY THIS AFTERNOON. AT THE SURFACE A 999MB
LOW IS LOCATED NEAR CINCINNATI, OHIO, WITH A WIND SHIFT TO
NORTHWESTERLY BEHIND IT. ON THE BACK-SIDE OF THE LOW, A
DEFORMATION ZONE HAS DEVELOPED WITH SOME AREAS OF MODERATE SNOW IN
INDIANA.
THIS AFTERNOON...THE NORTHERN AND SOUTHERN BRANCHES WILL PHASE
INTO A MID-LEVEL TROUGH WITH THE SURFACE LOW MOVING INTO THE
NORTHWEST PENNSYLVANIA. EARLY THIS AFTERNOON, WET BULB ZERO LINE
WILL CONTINUE TO ALLOW FOR SLEET AND SNOW TO MIX IN, ALTHOUGH NO
ACCUMULATION IS EXPECTED WITH TEMPS ABOVE FREEZING. A RAIN/SNOW
MIX WILL LINGER THERE UNTIL PRECIP TURNS TO SNOW LATER THIS
AFTERNOON. THE 850MB LOW WILL PASS NORTHEAST OF THE AREA,
WRAPPING COLDER AIR IN BEHIND IT. IN ADDITION, RUC/NAM ARE SHOWING
700MB DEFORMATION ZONE SHIFTING ACROSS THE OHIO VALLEY AND BRINGING
A SHOT OF MODERATE SNOW TO EASTERN OHIO BY THE EARLY EVENING. AS
SURFACE WINDS SHIFT TO NORTHWESTERLY, THE CHANGEOVER TO SNOW
WILL QUICKLY ENSUE. WITH RECENT TRENDS IN OBS, THIS CHANGEOVER HAS
BEEN MOVED UP A FEW HOURS. TEMPS WILL RANGE FROM THE MID 40S
ACROSS NORTH- CENTRAL WV TO THE MID 3OS ACROSS THE I-80 CORRIDOR
AND REMAIN FAIRLY STEADY UNTIL THE WIND SHIFT OCCUR LATE THIS
AFTERNOON IN THE EARLY EVENING.
&&
.SHORT TERM /8 PM THIS EVENING THROUGH THURSDAY/...
THE TROUGH AND SURFACE LOW WILL SHIFT NORTHEAST OF THE
AREA INTO NEW YORK, WITH COLD AIR ADVECTION ALLOWING FOR
PRECIPITATION TO QUICKLY TURN OVER TO ALL SNOW. A 700MB
DEFORMATION ZONE WILL CROSS THE AREA, ALLOWING FOR AN INITIAL
QUICK BURST OF 1 TO 2 INCHES ACROSS MUCH OF THE AERA. AFTER THE
INITIAL BURST, A NORTHWESTERLY FLOW WILL ALLOW FOR SNOW SHOWERS
ACROSS THE AREA. UPSLOPING ACROSS THE RIDGES ALONG WITH A SLIGHTLY
FASTER CHANGEOVER AND SOME LAKE ENHANCEMENT FOR AREAS NORTH OF
PITTSBURGH WILL ALLOW FOR 2 TO 4 INCHES BY DAWN ON WEDNESDAY.
OVERNIGHT LOWS ARE CLOSE TO LAMP GUIDANCE, RANGING FROM THE MID TO
UPPER 20S ACROSS THE AREA. THE QUICK DROP BELOW FREEZING BY
MIDNIGHT, WILL LEAD TO SOME ICY AND SNOW-COVERED ROADS THROUGH
DAWN.
LAKE EFFECT SNOW SHOWERS WILL LINGER EARLY ON WEDNESDAY, ALTHOUGH
DO NOT EXPECT ACCUMULATIONS TO AMOUNT TO MORE THAN AN INCH WITH
LOWERED INVERSION HEIGHTS LIMITING INSTABILITY. A SURFACE HIGH WILL
THEN BUILD IN THROUGH THURSDAY. TEMPERATURES WILL BE BELOW NORMAL BUT
CONDITIONS SHOULD BE DRY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
FAST MOVING SYSTEMS IN PROGRESSIVE FLOW WILL BRING TEMPERATURES
AVERAGING ABOVE NORMAL AND CHANCES FOR RAIN OR SNOW SHOWERS FOR
LATE WEEK INTO THE WEEKEND. LONG TERM PERIOD WAS FORECAST CLOSE TO
HPC PROGS WHICH CONTINUE TO TREND TOWARD THE ECMWF.
&&
.AVIATION /16Z TUESDAY THROUGH SATURDAY/...
VFR CONDITIONS CAN BE EXPECTED IN THE IMMEDIATE POST DAWN ALTHOUGH
CLOUD LEVEL WILL BE STEADILY LOWERING AS MOISTURE BEING PUSHED IN
ADVANCE OF APPROACHING LOW PRES OVERCOMES DEEP DRY LAYER OVR THE UPR
OHIO REGION.
CONFIDENCE IS HIGH THAT CONDITIONS WILL DETERIORATE TO IFR BY MIDDAY
AS THAT LOW CONTS A NEWD TREK AND THE UPR OHIO VALLEY ATMOSPHERE
SATURATES. PROJECTED PASSAGE OF THE LOW ACRS OHIO WOULD ENSURE THAT
WARM ADVECTION ON THE ERN FLANK OF THAT SYSTEM WILL CHANGE ANY
MIXED PRECIP AT KDUJ/KFKL BRIEFLY TO RAIN THIS AFTERNOON BEFORE
PRECIP TURNS BACK OVER TO ALL SNOW. OTHER CONCERN FOR THE MIDDAY
PERIOD WL BE THE LLWS POTENTIAL AS WIND SPEED ABOVE THE BOUNDARY
LAYER WL INCRS SIGNIFICANTLY WITH PASSAGE OF THE LOW. CONFIDENCE
IN THAT POTENTIAL IS SUFFICIENTLY HIGH TO INCLUDE IN ALL TAFS.
IFR CAN BE EXPECTED INTO TUESDAY NIGHT AS PRECIPITATION TRANSITIONS
TO SNOW IN THE COLD ADVECTION ON THE WRN SIDE OF THE EXITING LOW.
CIGS MAY IMPROVE DURING THE OVRNGT TO MVFR LEVELS...BUT IFR
VISIBILITY IN SNOW SHOWERS SHOULD CONT TO PLAGUE AREA PORTS.
OUTLOOK...WEDNESDAY THROUGH SATURDAY...
CONDITIONS SHOULD GRADUALLY IMPROVE TO VFR BY LATE WEDNESDAY AS A
WEAK SURFACE RIDGE MOVES EAST. A SERIES OF FAST MOVING WEATHER
SYSTEMS WILL THEN CROSS THE REGION DURING THE LATTER HALF OF THE
WEEK WITH PERIODIC RESTRICTIONS.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR MDZ001.
OH...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST
WEDNESDAY FOR OHZ041.
PA...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 4 AM EST
WEDNESDAY FOR PAZ007>009-013-015-016.
WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR PAZ014-020>023-073>076.
WV...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST
WEDNESDAY FOR WVZ023-041.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1242 PM EST TUE DEC 27 2011
LATEST UPDATE...AVIATION...
.SYNOPSIS...(450 AM EST TUE DEC 27 2011)
LOW PRESSURE MOVING NORTH FROM THE SOUTHERN US WILL COMBINE WITH
COLDER AIR MOVING SOUTH FROM CANADA TO PRODUCE SOME LIGHT SNOW
TODAY. LIGHT RAIN MAY MIX WITH THE SNOW...ESPECIALLY THIS MORNING.
AN INCH OR TWO OF ACCUMULATION IS POSSIBLE WITH GREATEST AMOUNTS
SOUTHEAST OF A KALAMAZOO TO LANSING LINE. WEDNESDAY WILL BE OUR
COLDEST DAY WITH HIGHS AROUND 30. AFTER THAT HIGHS WILL CLIMB TO
NEAR 40 THROUGH THE WEEKEND. A CLIPPER SYSTEM WILL BRING A CHANCE OF
RAIN AND SNOW TO THE REGION THURSDAY.
&&
.SHORT TERM...(1115 AM EST TUE DEC 27 2011)
(TODAY THROUGH THURSDAY)
* ACCUMULATING SNOW WILL TAPER TO FLURRIES/LIGHT RAIN EARLY THIS
AFTERNOON WITH SNOW TOTALS OF 1 TO 3 INCHES...PRIMARILY GRASSY
SURFACES...SIGNIFICANT WEATHER ADVISORY WAS ISSUED AT 10 AM.
* GUSTY WINDS ALONG COAST THIS EVENING WILL BE LOOKING AT POSSIBLE
WIND ADVISORY FOR THE COAST...
RADAR INDICATING TWO BANDS OF MODERATE SNOW AT THE PRESENT TIME.
BOTH ARE ORIENTED SSW-NNE WITH ONE FROM KGRR TO KMOP...WITH THE
SECOND BAND ALONG A KOEB...KJXN...KFNT LINE. BOTH BANDS ARE SLOWLY
MOVING EAST AND ARE EXPECTED TO WEAKEN AS THE MIDLEVEL FRONTOGENESIS
SHIFT TO THE NORTHEAST AND SURFACE COLD FRONT SWEEPS EASTWARD THIS
AFTERNOON.
THE HRRR RUC HAS HAD A REALLY GOOD HANDLE ON THE EVOLUTION OF THE
SYSTEM THIS MORNING AND HAVE LEVERAGED IT HEAVILY IN UPDATING
SNOWFALL GRIDS. ALTHOUGH...HALF OF THE SNOW HAS FALLEN...LOOKS LIKE
LOCAL TOTALS OF 3 INCHES ARE LIKELY. TEMPERATURES ARE EXPECTED TO
RISE INTO THE MID 30S THIS AFTERNOON AS THE SNOW TAPERS OFF AND MAY
EVEN END AS A MIX WITH RAIN BEFORE ENDING.
THIS EVENING WINDS WILL KICK UP AS COLDER AIR FLOWS IN BEHIND THE
LOW AS IT MOVES BY TO THE SOUTHEAST. STRONGEST WINDS WILL BE NEAR
THE LAKE SHORE. PCPN WILL DIMINISH THIS EVENING. THERE MAY BE A FEW
SNOW SHOWERS ALONG THE LAKE SHORE IN NORTH FLOW AS H8 TEMPS FALL
BRIEFLY TO AROUND -12C. MOISTURE IS SHALLOW THOUGH AND NOTHING
ORGANIZED IS EXPECTED.
THE NEXT CLIPPER WILL MOVE TOWARD THE REGION WEDNESDAY NIGHT AND
THURSDAY. AS HAS BEEN TYPICAL LATELY...THIS SYSTEM WILL SCOOT BY TO
THE NORTH. THAT MEANS WE/LL SEE SOME WARMER AIR FLOW INTO THE CWA
AND MIXED RAIN/SNOW IS EXPECTED IN THE SRN CWA WITH MORE SNOW IN THE
NORTH. APPRECIABLE ACCUMS ARE NOT EXPECTED.
&&
.LONG TERM...(450 AM EST TUE DEC 27 2011)
(THURSDAY NIGHT THROUGH MONDAY)
ZONAL FLOW IS FORECAST TO CONTINUE OVER THE LOWER 48 FOR MUCH OF THE
LONG TERM...TRANSITIONING TO AN EASTERN TROUGH/WESTERN RIDGE TOWARD
THE END OF THE PERIOD. GENERALLY LIGHT PRECIPITATION IS EXPECTED
THROUGH THE PERIOD. TIMING ISSUES ARE ALWAYS A CONCERN IN ZONAL FLOW
AND THIS FORECAST IS NO EXCEPTION.
FIRST WEAK SHORTWAVE TO DEAL WITH IS MOVING THROUGH THE GREAT LAKES
THURSDAY NIGHT. LOOKS LIKE MAINLY LIGHT SNOW...WITH QPF TOTALS THAT
ARE ON THE ORDER OF 0.10 OR LESS...SO NO ISSUES EXPECTED. THE
EUROPEAN HAS ANOTHER WAVE AFFECTING THE AREA FRIDAY INTO FRIDAY
NIGHT..WHILE THE GFS HAS RIDGING BUILDING IN. MAINTAINED SOME SMALL
POPS AT THIS POINT. HOPING FOR SOME BETTER CONSISTENCY...OBVIOUSLY
LOW CONFIDENCE OUT IN THE FRIDAY AND FRIDAY NIGHT TIME FRAME.
SATURDAY SHOULD BE MAINLY DRY WITH THE NEXT SYSTEM MOVING IN FOR
LATER IN THE WEEKEND. TIMING ISSUES CONTINUE WITH THE GFS BLASTING A
COLD FRONT THROUGH QUICKER...BY SUNDAY MORNING. THE EURO HOLDS THE
FRONT UP BY 12 HOURS OR SO. COLDER AIR IS PROGD TO FILTER IN BEHIND
THIS SYSTEM...WITH THE EURO INDICATING -16 C AIR OVER LAKE MICHIGAN
MONDAY AFTERNOON. GIVEN CONSISTENCY/TIMING ISSUES THE BULK OF THE
LONG TERM...LOW CONFIDENCE OVERALL. MADE LITTLE IN THE WAY OF
CHANGES AT THIS POINT.
&&
.AVIATION...(1242 PM EST TUE DEC 27 2011)
THE BACK EDGE OF THE STEADY SNOW EXTENDED FROM MOP TO AZO AS OF
1730Z. EAST OF THIS LINE IFR AND LIFR CONDITIONS PREVAIL.
MEANWHILE TO THE WEST OF THIS LINE VSBYS GREATLY IMPROVE...HOWEVER
CEILINGS REMAIN LARGELY IFR. THE SNOW SWATH AND LOWER VSBYS WILL
CONTINUE TO END FROM WEST TO EAST...REACHING LAN AND JXN AROUND
00Z. SURFACE WINDS AND MIXING WILL GREATLY INCREASE EARLY THIS
EVENING. THIS WILL HELP MOVE OUT ANY REMAINING IFR CEILINGS BY 03Z.
VFR/MVFR CONDITIONS ARE EXPECTED OVERNIGHT...HOWEVER NW WINDS WILL
OCCASIONALLY GUST AS HIGH AS 30 KNOTS. THESE WINDS WILL TAPER OFF
TOWARD DAYBREAK ON WED. CONDITIONS FINALLY LOOK FAVORABLE FOR VFR
FLYING WITH LIGHTER WINDS BY ABOUT 10Z WED AND SHOULD PREVAIL
THROUGH 18Z WED.
&&
.MARINE...(1115 AM EST TUE DEC 27 2011)
WINDS WILL BEGIN RAMPING UP EARLY THIS AFTERNOON AND GUST TO GALE
FORCE BY EARLY EVENING. GALE WARNING THROUGH THIS EVENING WITH GUST
AROUND 35 KTS.
&&
.HYDROLOGY...(450 AM EST TUE DEC 27 2011)
NO SIGNIFICANT CHANGES TO RIVERS EXPECTED FOR THE NEXT SEVERAL DAYS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...GALE WARNING ALL AREAS THROUGH TONIGHT.
&&
$$
SYNOPSIS: 93
SHORT TERM: COBB
LONG TERM: DUKE
AVIATION: JK
MARINE: COBB
HYDROLOGY: 93
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1115 AM EST TUE DEC 27 2011
LATEST UPDATE...MARINE AND SHORT TERM...
.SYNOPSIS...(450 AM EST TUE DEC 27 2011)
LOW PRESSURE MOVING NORTH FROM THE SOUTHERN US WILL COMBINE WITH
COLDER AIR MOVING SOUTH FROM CANADA TO PRODUCE SOME LIGHT SNOW
TODAY. LIGHT RAIN MAY MIX WITH THE SNOW...ESPECIALLY THIS MORNING.
AN INCH OR TWO OF ACCUMULATION IS POSSIBLE WITH GREATEST AMOUNTS
SOUTHEAST OF A KALAMAZOO TO LANSING LINE. WEDNESDAY WILL BE OUR
COLDEST DAY WITH HIGHS AROUND 30. AFTER THAT HIGHS WILL CLIMB TO
NEAR 40 THROUGH THE WEEKEND. A CLIPPER SYSTEM WILL BRING A CHANCE OF
RAIN AND SNOW TO THE REGION THURSDAY.
&&
.SHORT TERM...(1115 AM EST TUE DEC 27 2011)
(TODAY THROUGH THURSDAY)
* ACCUMULATING SNOW WILL TAPER TO FLURRIES/LIGHT RAIN EARLY THIS
AFTERNOON WITH SNOW TOTALS OF 1 TO 3 INCHES...PRIMARILY GRASSY
SURFACES...SIGNIFICANT WEATHER ADVISORY WAS ISSUED AT 10 AM.
* GUSTY WINDS ALONG COAST THIS EVENING WILL BE LOOKING AT POSSIBLE
WIND ADVISORY FOR THE COAST...
RADAR INDICATING TWO BANDS OF MODERATE SNOW AT THE PRESENT TIME.
BOTH ARE ORIENTED SSW-NNE WITH ONE FROM KGRR TO KMOP...WITH THE
SECOND BAND ALONG A KOEB...KJXN...KFNT LINE. BOTH BANDS ARE SLOWLY
MOVING EAST AND ARE EXPECTED TO WEAKEN AS THE MIDLEVEL FRONTOGENSIS
SHIFT TO THE NORTHEAST AND SURFACE COLD FRONT SWEEPS EASTWARD THIS
AFTERNOON.
THE HRRR RUC HAS HAD A REALLY GOOD HANDLE ON THE EVOLUTION OF THE
SYSTEM THIS MORNING AND HAVE LEVERAGED IT HEAVILY IN UPDATING
SNOWFALL GRIDS. ALTHOUGH...HALF OF THE SNOW HAS FALLEN...LOOKS LIKE
LOCAL TOTALS OF 3 INCHES ARE LIKELY. TEMPERATURES ARE EXPECTED TO
RISE INTO THE MID 30S THIS AFTERNOON AS THE SNOW TAPERS OFF AND MAY
EVEN END AS A MIX WITH RAIN BEFORE ENDING.
THIS EVENING WINDS WILL KICK UP AS COLDER AIR FLOWS IN BEHIND THE
LOW AS IT MOVES BY TO THE SOUTHEAST. STRONGEST WINDS WILL BE NEAR
THE LAKE SHORE. PCPN WILL DIMINISH THIS EVENING. THERE MAY BE A FEW
SNOW SHOWERS ALONG THE LAKE SHORE IN NORTH FLOW AS H8 TEMPS FALL
BRIEFLY TO AROUND -12C. MOISTURE IS SHALLOW THOUGH AND NOTHING
ORGANIZED IS EXPECTED.
THE NEXT CLIPPER WILL MOVE TOWARD THE REGION WEDNESDAY NIGHT AND
THURSDAY. AS HAS BEEN TYPICAL LATELY...THIS SYSTEM WILL SCOOT BY TO
THE NORTH. THAT MEANS WE/LL SEE SOME WARMER AIR FLOW INTO THE CWA
AND MIXED RAIN/SNOW IS EXPECTED IN THE SRN CWA WITH MORE SNOW IN THE
NORTH. APPRECIABLE ACCUMS ARE NOT EXPECTED.
&&
.LONG TERM...(450 AM EST TUE DEC 27 2011)
(THURSDAY NIGHT THROUGH MONDAY)
ZONAL FLOW IS FORECAST TO CONTINUE OVER THE LOWER 48 FOR MUCH OF THE
LONG TERM...TRANSITIONING TO AN EASTERN TROUGH/WESTERN RIDGE TOWARD
THE END OF THE PERIOD. GENERALLY LIGHT PRECIPITATION IS EXPECTED
THROUGH THE PERIOD. TIMING ISSUES ARE ALWAYS A CONCERN IN ZONAL FLOW
AND THIS FORECAST IS NO EXCEPTION.
FIRST WEAK SHORTWAVE TO DEAL WITH IS MOVING THROUGH THE GREAT LAKES
THURSDAY NIGHT. LOOKS LIKE MAINLY LIGHT SNOW...WITH QPF TOTALS THAT
ARE ON THE ORDER OF 0.10 OR LESS...SO NO ISSUES EXPECTED. THE
EUROPEAN HAS ANOTHER WAVE AFFECTING THE AREA FRIDAY INTO FRIDAY
NIGHT..WHILE THE GFS HAS RIDGING BUILDING IN. MAINTAINED SOME SMALL
POPS AT THIS POINT. HOPING FOR SOME BETTER CONSISTENCY...OBVIOUSLY
LOW CONFIDENCE OUT IN THE FRIDAY AND FRIDAY NIGHT TIME FRAME.
SATURDAY SHOULD BE MAINLY DRY WITH THE NEXT SYSTEM MOVING IN FOR
LATER IN THE WEEKEND. TIMING ISSUES CONTINUE WITH THE GFS BLASTING A
COLD FRONT THROUGH QUICKER...BY SUNDAY MORNING. THE EURO HOLDS THE
FRONT UP BY 12 HOURS OR SO. COLDER AIR IS PROGD TO FILTER IN BEHIND
THIS SYSTEM...WITH THE EURO INDICATING -16 C AIR OVER LAKE MICHIGAN
MONDAY AFTERNOON. GIVEN CONSISTENCY/TIMING ISSUES THE BULK OF THE
LONG TERM...LOW CONFIDENCE OVERALL. MADE LITTLE IN THE WAY OF
CHANGES AT THIS POINT.
&&
.AVIATION...(715 AM EST TUE DEC 27 2011)
PRECIPITATION HAS OVERSPREAD ALL OF THE TAF SITES THIS
MORNING...WITH A MIXTURE OF RAIN AND SNOW ACROSS THE AREA. THE TREND
SHOULD BE TO ALL SNOW BY MID MORNING. CEILINGS ARE TRENDING DOWN
AND THAT SHOULD CONTINUE TO BE THE CASE THROUGH THE MORNING HOURS.
BY LATE MORNING...CONDITIONS WILL BE POOR RANGING FROM IFR TO LIFR.
AN IMPROVEMENT WILL OCCUR SLOWLY THIS AFTERNOON FROM WEST TO EAST AS
THE SYSTEM RESPONSIBLE FOR THE SNOW PULLS AWAY TO THE EAST. MVFR
CONDITIONS ARE EXPECTED BY MID TO LATE AFTERNOON. CONDITIONS WILL
IMPROVE TO VFR TONIGHT...WITH SOME VFR CEILINGS EXPECTED OFF OF LAKE
MICHIGAN.
IT WILL BECOME WINDY THIS AFTERNOON...ESPECIALLY AT KMKG WITH A
NORTHWEST WIND OFF THE LAKE. GUSTS WILL RANGE FROM 20 TO 30 KNOTS AT
MOST LOCATIONS THIS AFTERNOON AND EVENING FROM THE NORTHWEST.
&&
.MARINE...(1115 AM EST TUE DEC 27 2011)
WINDS WILL BEGIN RAMPING UP EARLY THIS AFTERNOON AND GUST TO GALE
FORCE BY EARLY EVENING. GALE WARNING THROUGH THIS EVENING WITH GUST
AROUND 35 KTS.
&&
.HYDROLOGY...(450 AM EST TUE DEC 27 2011)
NO SIGNIFICANT CHANGES TO RIVERS EXPECTED FOR THE NEXT SEVERAL DAYS.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...GALE WARNING ALL AREAS THROUGH TONIGHT.
&&
$$
SYNOPSIS: 93
SHORT TERM: COBB
LONG TERM: DUKE
AVIATION: DUKE
MARINE: COBB
HYDROLOGY: 93
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1143 PM CST WED DEC 28 2011
.AVIATION... /06Z TAF ISSUANCE/
THREAT FOR FREEZING RAIN LINGERS AT KSTC...KRNH AND KEAU UNTIL
08Z AS LOW PRESSURE AND A WARM FRONT MOVE THROUGH. CEILINGS ARE
BEGINNING TO DETERIORATE ALONG AND AHEAD OF A WARM FRONT. EXPECT
MVFR TO SETTLE IN BETWEEN 09Z AND 11Z AND LAST THROUGH MUCH OF THE
MORNING BEFORE SCATTERING OUT IN THE EARLY AFTERNOON. ANOTHER WAVE
OF LOW PRESSURE WILL MOVE ACROSS THURSDAY NIGHT...MUCH LIKE THE
CURRENT ONE. HOWEVER...THE LOW TOMORROW NIGHT WILL BE STRONGER AND
PROFILE DATA SUGGESTS IT WILL BE COLDER. HENCE...SNOW IS THE MAIN
EVENT. MODEL TRENDS ARE PAINTING A PRETTY BLEAK PICTURE FOR KMSP
AND KRNH AND KEAU WITH SNOW ACCUMULATION DURING THE LATE EVENING
AND OVERNIGHT HOURS. MVFR OR LOWER CEILINGS/VISIBILITIES WILL
ACCOMPANY THE SNOW.
KMSP...LIGHT RAIN PUSHING EAST OF THE AIRFIELD WITH BKN-OVC035-040
FOR A FEW HOURS. MVFR CEILINGS STILL EXPECTED TOWARDS DAYBREAK IN
THE WAKE OF A LOW PRESSURE SYSTEM MOVING INTO WEST CENTRAL MN
ATTM. THESE SHOULD PERSIST THROUGH THE MORNING WITH A VFR
AFTERNOON. POTENTIAL FOR MVFR OR LOWER CEILINGS QUITE HIGH FOR
THURSDAY NIGHT AND FRIDAY MORNING AS ANOTHER WAVE OF LOW PRESSURE
MOVES THROUGH. SNOW SHOULD ACCOMPANY THIS ONE TOMORROW NIGHT WITH
SOME ACCUMULATION POSSIBLE.
&&
.UPDATED... /ISSUED 816 PM CST WED DEC 28 2011/
HAVE ISSUED A WINTER WEATHER ADVISORY THROUGH 3 AM THURSDAY FOR
MUCH OF CENTRAL MN AND WEST CENTRAL WI. LIGHT RAIN HAS SPREAD INTO
WEST CENTRAL MN THIS EVENING AHEAD OF A LOW PRESSURE SYSTEM OVER
ND. TEMPERATURES ARE IN THE MIDDLE 30S AROUND ALEXANDRIA BUT
FURTHER EAST TEMPERATURES ARE AT OR BELOW FREEZING. PAVEMENT
TEMPERATURES ACROSS CENTRAL MN AND PARTS OF WEST CENTRAL WI ARE
AROUND 30 DEGREES AS WELL. HENCE...THE POTENTIAL FOR FREEZING RAIN
IS INCREASING. COMPLICATING MATTERS IS THAT ICE INCREASES IN THE
COLUMN TO THE NORTH AND EAST OF THE TWIN CITIES WITH THE PRECIP
TYPE MORE LIKELY TO BE SNOW WITH A CHANCE OF FREEZING RAIN.
&&
.DISCUSSION... /ISSUED 352 PM CST WED DEC 28 2011/
SUMMARY...PATTERN IS A BIT MORE ACTIVE OVER THE NEXT SEVERAL DAYS
IN TERMS OF CHANCES OF PRECIPITATION THAN IT HAS BEEN IN QUITE
SOME TIME. OVERALL...THE OUTLOOK REMAINS WARM SO THE PRECIP EVENTS
EXPECTED TONIGHT...THURSDAY NIGHT AND SATURDAY NIGHT WILL LIKELY
HAVE SOME LIQUID PRECIPITATION ASSOCIATED WITH EACH OF THEM. NO
MAJOR SYSTEMS EXPECTED AND MAXIMUM QPF WITH EACH EVENT SHOULD
LARGELY BE BELOW A QUARTER INCH...A COUPLE OUTLIER RUNS OF THE
NAM/GEM WOULD SUGGEST HIGHER QPF TOTALS WITH THE THURSDAY NIGHT
AND SATURDAY NIGHT SYSTEMS.
THE INTERIOR OF CANADA HAS COOLED SINCE THE LAST TIME I WAS ON A
FORECAST SHIFT LATE LAST WEEK...BUT STILL NO TRUE ARCTIC AIR
ENCROACHING ON THE US CONUS. THE ARCTIC AIR IS STILL BEING
CONFINED TO THE HIGHER LATITUDES...LARGELY ABOVE 55-60 DEGREES
NORTH. PACIFIC AIR MASSES WILL CONTINUE TO IMPACT THE US THROUGH
THE END OF THE YEAR. PROGRESSIVE UPPER FLOW WILL BE FEATURED AS A
SERIES OF DISTURBANCES SURGE FROM THE NORTHEASTERN PACIFIC AND
INTO THE PACIFIC NORTHWEST. THE SOUTHWARD EXTENT OF THIS UPPER
TROUGH SHOULD BE LIMITED BY A RIDGE ACROSS THE SOUTHWEST US. AS A
RESULT...THE SWATH OF PRECIPITATION SHOULD NOT EXTEND MUCH FARTHER
SOUTH THAN 40 DEGREES NORTH. THIS WILL KEEP MN AND WI UNDER THE
GUN FOR A FEW LIGHT PRECIPITATION EVENTS OVER THE COMING DAYS.
THE FAST MOVING FLOW ALOFT WILL KEEP UNSETTLED CONDITIONS IN PLACE
FOR MUCH OF THE PACIFIC NORTHWEST...NORTHERN ROCKIES AND UPPER
MISSISSIPPI VALLEY THROUGH THE WEEKEND. THE FIRST IN A PAIR OF
SYSTEMS IS CURRENTLY MOVING OUT OF THE NORTHERN ROCKIES AND INTO
THE NORTHERN PLAINS. LIGHT RAIN IS RAPIDLY PUSHING INTO THE
EASTERN DAKOTAS LATE THIS AFTERNOON AND THE HRRR TREND IS TAKE THE
LIGHT RAIN INTO WESTERN MN BETWEEN 00-03Z. IF THE CURRENT TRENDS
HOLD...MOST OF THE PRECIP WILL PUSH OUT OF THE FORECAST AREA
BETWEEN 06-09Z...A BIT FASTER THAN THE CURRENT FORECAST INDICATES.
ALSO SOME QUESTION WHETHER OR NOT THE MIXED PRECIPITATION WILL
REALLY PAN OUT IN PARTS OF CENTRAL/SOUTHERN MN. COOLING WILL BE
TOUGH WITH CLOUD COVER AND WEAK WARM AIR ADVECTION. IT MIGHT END
UP BEING NEARLY ALL LIGHT RAIN RATHER THAN SNOW OR FREEZING RAIN.
IN THE EXTENDED...INCREASINGLY MERIDIONAL FLOW WILL LEAD TO MORE
AMPLIFIED TROUGHS ACROSS THE EASTERN PACIFIC THROUGH THE GREAT
LAKES WITH RIDGING SANDWICHED IN BETWEEN. MOST OF THE GUIDANCE
AGREES ON THIS PATTERN...OUTSIDE THE 00Z GFS WHICH WAS BROAD AND
FLAT WITH THE EASTERN TROUGH DESPITE ITS AMPLIFIED RIDGE UPSTREAM.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR BENTON-
CHISAGO-ISANTI-KANABEC-MILLE LACS-MORRISON-SHERBURNE-
STEARNS-TODD.
WI...WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR BARRON-
CHIPPEWA-DUNN-EAU CLAIRE-POLK-RUSK-ST. CROIX.
&&
$$
RAH/RAH/CLF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
816 PM CST WED DEC 28 2011
.UPDATE...
HAVE ISSUED A WINTER WEATHER ADVISORY THROUGH 3 AM THURSDAY FOR
MUCH OF CENTRAL MN AND WEST CENTRAL WI. LIGHT RAIN HAS SPREAD INTO
WEST CENTRAL MN THIS EVENING AHEAD OF A LOW PRESSURE SYSTEM OVER
ND. TEMPERATURES ARE IN THE MIDDLE 30S AROUND ALEXANDRIA BUT FURTHER
EAST TEMPERATURES ARE AT OR BELOW FREEZING. PAVEMENT TEMPERATURES
ACROSS CENTRAL MN AND PARTS OF WEST CENTRAL WI ARE AROUND 30
DEGREES AS WELL. HENCE...THE POTENTIAL FOR FREEZING RAIN IS
INCREASING. COMPLICATING MATTERS IS THAT ICE INCREASES IN THE
COLUMN TO THE NORTH AND EAST OF THE TWIN CITIES WITH THE PRECIP
TYPE MORE LIKELY TO BE SNOW WITH A CHANCE OF FREEZING RAIN.
&&
.DISCUSSION... /ISSUED 352 PM CST WED DEC 28 2011/
SUMMARY...PATTERN IS A BIT MORE ACTIVE OVER THE NEXT SEVERAL DAYS
IN TERMS OF CHANCES OF PRECIPITATION THAN IT HAS BEEN IN QUITE
SOME TIME. OVERALL...THE OUTLOOK REMAINS WARM SO THE PRECIP EVENTS
EXPECTED TONIGHT...THURSDAY NIGHT AND SATURDAY NIGHT WILL LIKELY
HAVE SOME LIQUID PRECIPITATION ASSOCIATED WITH EACH OF THEM. NO
MAJOR SYSTEMS EXPECTED AND MAXIMUM QPF WITH EACH EVENT SHOULD
LARGELY BE BELOW A QUARTER INCH...A COUPLE OUTLIER RUNS OF THE
NAM/GEM WOULD SUGGEST HIGHER QPF TOTALS WITH THE THURSDAY NIGHT
AND SATURDAY NIGHT SYSTEMS.
THE INTERIOR OF CANADA HAS COOLED SINCE THE LAST TIME I WAS ON A
FORECAST SHIFT LATE LAST WEEK...BUT STILL NO TRUE ARCTIC AIR
ENCROACHING ON THE US CONUS. THE ARCTIC AIR IS STILL BEING
CONFINED TO THE HIGHER LATITUDES...LARGELY ABOVE 55-60 DEGREES
NORTH. PACIFIC AIR MASSES WILL CONTINUE TO IMPACT THE US THROUGH
THE END OF THE YEAR. PROGRESSIVE UPPER FLOW WILL BE FEATURED AS A
SERIES OF DISTURBANCES SURGE FROM THE NORTHEASTERN PACIFIC AND
INTO THE PACIFIC NORTHWEST. THE SOUTHWARD EXTENT OF THIS UPPER
TROUGH SHOULD BE LIMITED BY A RIDGE ACROSS THE SOUTHWEST US. AS A
RESULT...THE SWATH OF PRECIPITATION SHOULD NOT EXTEND MUCH FARTHER
SOUTH THAN 40 DEGREES NORTH. THIS WILL KEEP MN AND WI UNDER THE
GUN FOR A FEW LIGHT PRECIPITATION EVENTS OVER THE COMING DAYS.
THE FAST MOVING FLOW ALOFT WILL KEEP UNSETTLED CONDITIONS IN PLACE
FOR MUCH OF THE PACIFIC NORTHWEST...NORTHERN ROCKIES AND UPPER
MISSISSIPPI VALLEY THROUGH THE WEEKEND. THE FIRST IN A PAIR OF
SYSTEMS IS CURRENTLY MOVING OUT OF THE NORTHERN ROCKIES AND INTO
THE NORTHERN PLAINS. LIGHT RAIN IS RAPIDLY PUSHING INTO THE
EASTERN DAKOTAS LATE THIS AFTERNOON AND THE HRRR TREND IS TAKE THE
LIGHT RAIN INTO WESTERN MN BETWEEN 00-03Z. IF THE CURRENT TRENDS
HOLD...MOST OF THE PRECIP WILL PUSH OUT OF THE FORECAST AREA
BETWEEN 06-09Z...A BIT FASTER THAN THE CURRENT FORECAST INDICATES.
ALSO SOME QUESTION WHETHER OR NOT THE MIXED PRECIPITATION WILL
REALLY PAN OUT IN PARTS OF CENTRAL/SOUTHERN MN. COOLING WILL BE
TOUGH WITH CLOUD COVER AND WEAK WARM AIR ADVECTION. IT MIGHT END
UP BEING NEARLY ALL LIGHT RAIN RATHER THAN SNOW OR FREEZING RAIN.
IN THE EXTENDED...INCREASINGLY MERIDIONAL FLOW WILL LEAD TO MORE
AMPLIFIED TROUGHS ACROSS THE EASTERN PACIFIC THROUGH THE GREAT
LAKES WITH RIDGING SANDWICHED IN BETWEEN. MOST OF THE GUIDANCE
AGREES ON THIS PATTERN...OUTSIDE THE 00Z GFS WHICH WAS BROAD AND
FLAT WITH THE EASTERN TROUGH DESPITE ITS AMPLIFIED RIDGE UPSTREAM.
&&
.AVIATION... /00Z TAF ISSUANCE/
LOW PRESSURE AREA OVER ND TO MOVE INTO CENTRAL MN OVERNIGHT AND
INTO WEST CENTRAL WI BY THURSDAY MORNING. MAINLY VFR CIGS TO START
THE EVENING BUT LOWER TO MVFR LATE TONIGHT OVER CENTRAL MN. A RAIN
AND SNOW MIX IS LIKELY FROM NEAR KAXN TO KMSP...WITH MAINLY SNOW
TO THE NORTHEAST OF THAT LINE. VSBYS COULD GO BRIEFLY INTO THE
IFR CATEGORY. THERE IS AS RISK OF FREEZING RAIN IN THE ABOVE
MENTIONED CORRIDOR AS WELL. THE LENGTH OF TIME OF THE PRECIP WILL
NOT BE LONG GENERALLY LESS THAN 3 HOURS AS THE SYSTEM MOVES ACROSS
THE AREA OVERNIGHT. THERE IS A LOW RISK OF IFR CIGS THURSDAY
MORNING OVER CENTRAL MN BEHIND THE LOW PRESSURE AREA. WILL
INDICATE A SCT LAYER AT KAXN AND LOWER THE CIG A BIT AT KSTC.
MVFR CIGS WILL SCT OUT OVER PARTS OF WEST CENTRAL MN DURING THE
AFTERNOON BEFORE LOWER VFR CIGS MOVE IN FOR THE NEXT SYSTEM BY THE
END OF THE TAF PREIOD. HAVE ALSO INDICATED SOME RAIN BEGINNING AT
KRWF AFTER 22Z. WINDS SOUTH TO SOUTHEAST OVERNIGHT BECOMING
NORTHWEST BEHIND THE LOW PRESSURE. SPEEDS GENERALLY AT OR BELOW 10
KNOTS.
KMSP...VFR CIGS AS THE PRECIPITATION MOVES IN...THEN CLOSE TO MVFR
DURING THE BEST WINDOW OF PRECIP. PRECIPITATION TYPE PROBLEMATIC
AS WE WILL BE ON THE EDGE OF A RAIN/SNOW LINE. WILL NEED TO WATCH
THE TEMP TRENDS AS PRECIP MOVES IN AS THERE IS A LOW RISK OF
FREEZING RAIN. FOR NOW WILL GO WITH A RAIN AND SNOW MIX. HAVE
INDICATED JUST MVFR VSBYS BUT NEED TO WATCH THAT AS WELL. WILL BE
BRIEF IF IT DOES GO DOWN TO IFR. MVFR CIGS SHOULD MOVE IN AT OR
AFTER 12Z...AND PERSIST THROUGH THE MORNING. THE NEXT SYSTEM TO
BRING IN A CHANCE OF RAIN OR SNOW AFTER 00Z FRIDAY. THERE MAY BE A
WINDOW OF VFR CONDITIONS FOR THE AFTERNOON.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR BENTON-
CHISAGO-ISANTI-KANABEC-MILLE LACS-MORRISON-SHERBURNE-
STEARNS-TODD.
WI...WINTER WEATHER ADVISORY UNTIL 3 AM CST THURSDAY FOR BARRON-
CHIPPEWA-DUNN-EAU CLAIRE-POLK-RUSK-ST. CROIX.
&&
$$
RAH/CLF/JPR
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
612 PM CST WED DEC 28 2011
.UPDATE...
.AVIATION.../00Z TAF ISSUANCE/
LOW PRESSURE AREA OVER ND TO MOVE INTO CENTRAL MN OVERNIGHT AND
INTO WEST CENTRAL WI BY THURSDAY MORNING. MAINLY VFR CIGS TO START
THE EVENING BUT LOWER TO MVFR LATE TONIGHT OVER CENTRAL MN. A RAIN
AND SNOW MIX IS LIKELY FROM NEAR KAXN TO KMSP...WITH MAINLY SNOW
TO THE NORTHEAST OF THAT LINE. VSBYS COULD GO BRIEFLY INTO THE
IFR CATEGORY. THERE IS AS RISK OF FREEZING RAIN IN THE ABOVE
MENTIONED CORRIDOR AS WELL. THE LENGTH OF TIME OF THE PRECIP WILL
NOT BE LONG GENERALLY LESS THAN 3 HOURS AS THE SYSTEM MOVES ACROSS
THE AREA OVERNIGHT. THERE IS A LOW RISK OF IFR CIGS THURSDAY
MORNING OVER CENTRAL MN BEHIND THE LOW PRESSURE AREA. WILL
INDICATE A SCT LAYER AT KAXN AND LOWER THE CIG A BIT AT KSTC.
MVFR CIGS WILL SCT OUT OVER PARTS OF WEST CENTRAL MN DURING THE
AFTERNOON BEFORE LOWER VFR CIGS MOVE IN FOR THE NEXT SYSTEM BY THE
END OF THE TAF PREIOD. HAVE ALSO INDICATED SOME RAIN BEGINNING AT
KRWF AFTER 22Z. WINDS SOUTH TO SOUTHEAST OVERNIGHT BECOMING
NORTHWEST BEHIND THE LOW PRESSURE. SPEEDS GENERALLY AT OR BELOW 10
KNOTS.
KMSP...VFR CIGS AS THE PRECIPITATION MOVES IN...THEN CLOSE TO MVFR
DURING THE BEST WINDOW OF PRECIP. PRECIPITATION TYPE PROBLEMATIC
AS WE WILL BE ON THE EDGE OF A RAIN/SNOW LINE. WILL NEED TO WATCH
THE TEMP TRENDS AS PRECIP MOVES IN AS THERE IS A LOW RISK OF
FREEZING RAIN. FOR NOW WILL GO WITH A RAIN AND SNOW MIX. HAVE
INDICATED JUST MVFR VSBYS BUT NEED TO WATCH THAT AS WELL. WILL BE
BRIEF IF IT DOES GO DOWN TO IFR. MVFR CIGS SHOULD MOVE IN AT OR
AFTER 12Z...AND PERSIST THROUGH THE MORNING. THE NEXT SYSTEM TO
BRING IN A CHANCE OF RAIN OR SNOW AFTER 00Z FRIDAY. THERE MAY BE A
WINDOW OF VFR CONDITIONS FOR THE AFTERNOON.
&&
&&
.DISCUSSION...
SUMMARY...PATTERN IS A BIT MORE ACTIVE OVER THE NEXT SEVERAL DAYS
IN TERMS OF CHANCES OF PRECIPITATION THAN IT HAS BEEN IN QUITE
SOME TIME. OVERALL...THE OUTLOOK REMAINS WARM SO THE PRECIP EVENTS
EXPECTED TONIGHT...THURSDAY NIGHT AND SATURDAY NIGHT WILL LIKELY
HAVE SOME LIQUID PRECIPITATION ASSOCIATED WITH EACH OF THEM. NO
MAJOR SYSTEMS EXPECTED AND MAXIMUM QPF WITH EACH EVENT SHOULD
LARGELY BE BELOW A QUARTER INCH...A COUPLE OUTLIER RUNS OF THE
NAM/GEM WOULD SUGGEST HIGHER QPF TOTALS WITH THE THURSDAY NIGHT
AND SATURDAY NIGHT SYSTEMS.
THE INTERIOR OF CANADA HAS COOLED SINCE THE LAST TIME I WAS ON A
FORECAST SHIFT LATE LAST WEEK...BUT STILL NO TRUE ARCTIC AIR
ENCROACHING ON THE US CONUS. THE ARCTIC AIR IS STILL BEING
CONFINED TO THE HIGHER LATITUDES...LARGELY ABOVE 55-60 DEGREES
NORTH. PACIFIC AIR MASSES WILL CONTINUE TO IMPACT THE US THROUGH
THE END OF THE YEAR. PROGRESSIVE UPPER FLOW WILL BE FEATURED AS A
SERIES OF DISTURBANCES SURGE FROM THE NORTHEASTERN PACIFIC AND
INTO THE PACIFIC NORTHWEST. THE SOUTHWARD EXTENT OF THIS UPPER
TROUGH SHOULD BE LIMITED BY A RIDGE ACROSS THE SOUTHWEST US. AS A
RESULT...THE SWATH OF PRECIPITATION SHOULD NOT EXTEND MUCH FARTHER
SOUTH THAN 40 DEGREES NORTH. THIS WILL KEEP MN AND WI UNDER THE
GUN FOR A FEW LIGHT PRECIPITATION EVENTS OVER THE COMING DAYS.
THE FAST MOVING FLOW ALOFT WILL KEEP UNSETTLED CONDITIONS IN PLACE
FOR MUCH OF THE PACIFIC NORTHWEST...NORTHERN ROCKIES AND UPPER
MISSISSIPPI VALLEY THROUGH THE WEEKEND. THE FIRST IN A PAIR OF
SYSTEMS IS CURRENTLY MOVING OUT OF THE NORTHERN ROCKIES AND INTO
THE NORTHERN PLAINS. LIGHT RAIN IS RAPIDLY PUSHING INTO THE
EASTERN DAKOTAS LATE THIS AFTERNOON AND THE HRRR TREND IS TAKE THE
LIGHT RAIN INTO WESTERN MN BETWEEN 00-03Z. IF THE CURRENT TRENDS
HOLD...MOST OF THE PRECIP WILL PUSH OUT OF THE FORECAST AREA
BETWEEN 06-09Z...A BIT FASTER THAN THE CURRENT FORECAST INDICATES.
ALSO SOME QUESTION WHETHER OR NOT THE MIXED PRECIPITATION WILL
REALLY PAN OUT IN PARTS OF CENTRAL/SOUTHERN MN. COOLING WILL BE
TOUGH WITH CLOUD COVER AND WEAK WARM AIR ADVECTION. IT MIGHT END
UP BEING NEARLY ALL LIGHT RAIN RATHER THAN SNOW OR FREEZING RAIN.
IN THE EXTENDED...INCREASINGLY MERIDIONAL FLOW WILL LEAD TO MORE
AMPLIFIED TROUGHS ACROSS THE EASTERN PACIFIC THROUGH THE GREAT
LAKES WITH RIDGING SANDWICHED IN BETWEEN. MOST OF THE GUIDANCE
AGREES ON THIS PATTERN...OUTSIDE THE 00Z GFS WHICH WAS BROAD AND
FLAT WITH THE EASTERN TROUGH DESPITE ITS AMPLIFIED RIDGE UPSTREAM.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
&&
$$
CLF/JPR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1033 AM CST TUE DEC 27 2011
.DISCUSSION...
MORNING UPDATE CONCENTRATES ON SKY AND TEMPS. EARLY VIS SHOWED
STRATOCU DECK EAST OF THE VALLEY...HOWEVER IT IS QUICKLY BREAKING
UP AS EVIDENT FROM WEB CAMS OVER THE BJI AREA. THUS BUMPED UP SKY
FROM 15Z TO 21Z AND THEN BEGAN TO SCATTER IT BACK OUT. LIKELY
SCENARIO IS THAT CIRRUS WILL ARRIVE BEFORE SCATTERING COMPLETELY
OUT. LATEST NAM ISENTROPIC CHARTS AND LOW LEVEL WARM ADVECTION
STARTING TO KICK IN AROUND 21Z...THUS NOT SURE WE WILL SEE ANY
SNOW OUT WEST IN THE 18Z TO 21Z TIMEFRAME...BUT BY 00Z IT IS A
POSSIBILITY. CURRENT POP GRIDS LOOK DECENT ALTHOUGH MAY PULL 18Z
TO 21Z POPS AFTER FURTHER ANALYSIS. TEMPS CURRENTLY COLDER THAN
PREV FCST ADVERTISED...BUT WITH WARM ADVECTION KICKING IN MID AFTN
THINK FCST HIGHS ARE REASONABLE DESPITE CIRRUS. MADE ADJUSTMENTS TO
HOURLY TEMPS TO COMPENSATE FOR CURRENT OBS AND A LATER START.
&&
.AVIATION...
LOW CLOUDS WITH MVFR/LCLLY IFR/ PTCHY 4SM -SN CONTINUE OVER PORTIONS
OF NORTHWEST MINNESOTA. CLOUD DECK APPEARS THIN AND IS MOVING DUE
SOUTH AROUND 10 KTS. RUC13 MODEL X-SECT AND SAT/11-3.9/ SUGGEST
SHOULD CLEAR TVF AROUND 18Z BUT HOLD IN BJI AREA THROUGH 00Z. WINDS
WILL CONTINUE TO DECREASE AND BECOME VRB AROUND 00Z TVF/BJI WITH SFC
RIDGE OVER AREA. VFR ALONG AND WEST OF RRV THROUGH 00Z. A BAND OF
LIGHT SNOW WITH MVFR CEILINGS IS EXPECTED OVERNIGHT...BUT
ADJUSTMENTS IN TIMING ARE LIKELY THROUGH THE DAY.
&&
.PREV DISCUSSION... /ISSUED 356 AM CST TUE DEC 27 2011/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
PRIMARY FORECAST CHALLENGE WILL BE PRECIPITATION CHANCES AND AMOUNTS
TONIGHT THROUGH MUCH OF THE WEEK AS A SERIES OF WAVES MOVE ACROSS
THE NORTHERN PLAINS IN FAST NORTHWEST FLOW ALOFT. GFS/ECMWF/GEM IN
REASONABLE AGREEMENT THROUGH THURSDAY MORNING...DIVERGING SOMEWHAT
THEREAFTER. THE NAM IS A BIT OF AN OUTLIER AND WILL NOT BE USED IN
THIS FORECAST PACKAGE.
COLD FRONT FROM LAST EVENING HAS MOVED WELL SOUTH OF THE FORECAST
AREA WITH STRONG COLD AIR ADVECTION AND BREEZY NORTHERLY WINDS IN
ITS WAKE. SURFACE TEMPERATURES ACROSS SOUTHERN MANITOBA ARE IN THE
LOW SINGLE DIGITS ABOVE ZERO AND THIS COLD AIR WILL CONTINUE TO
FILTER TO THE SOUTH THROUGH THE EARLY MORNING HOURS. LOW STRATUS
ALONG AND SOUTHEAST OF A LINE FROM JAMESTOWN TO GRAND FORKS TO
ROSEAU WILL CONTINUE TO SLIDE SOUTH AND EAST...RESULTING IN MOSTLY
SUNNY SKIES BY MID TO LATE MORNING REGION WIDE. NORTH WINDS WILL
RELAX THROUGH THE DAY AS THE PRESSURE GRADIENT WEAKENS AND
SURFACE HIGH PRESSURE MOVES INTO THE NORTHERN PLAINS. WITH A
DRAMATIC CHANGE IN THE AIR MASS...TEMPERATURES TODAY WILL BE 20
TO 30 DEGREES LOWER THAN YESTERDAY/S RECORD HIGHS.
FOR TONIGHT...A NARROW BAND OF LIGHT SNOW WILL MOVE FROM WEST TO
EAST ACROSS THE FORECAST AREA...COINCIDENT WITH INCREASING MID-
LEVEL WARM AIR ADVECTION/CLOUD COVER AND MODEST ISENTROPIC LIFT ON
THE 280 K SURFACE. ACCUMULATIONS WILL BE LIGHT...BUT SOME SPOTS
MAY RECEIVE UP TO AN INCH OF NEW SNOW BY WEDNESDAY MORNING.
ANOTHER WAVE WILL MOVE THROUGH THE REGION WEDNESDAY AND WEDNESDAY
NIGHT...BRINGING A BETTER CHANCE OF ACCUMULATING SNOW (1-2 INCHES)
ACROSS PORTIONS OF EASTERN ND AND NORTHWEST MN. THE ECMWF AND GEM
SURFACE LOW TRACKS ARE A BIT FARTHER SOUTH THAN THE GFS...BUT ALL
THREE MODELS SHOW A BAND OF ROUGHLY ONE TENTH OF AN INCH LIQUID
QPF BISECTING THE FORECAST AREA FROM NORTHWEST TO SOUTHEAST. ECMWF
RUN TO RUN CONSISTENCY IS SLIGHTLY BETTER THAN THE GFS...SO PREFER
ITS MORE SOUTHERN SOLUTION...WHICH PLACES THE MOST PRECIPITATION
ALONG A RUGBY TO VALLEY CITY TO WAHPETON LINE. DUE TO DIFFERENCES
IN TRACK...WILL KEEP POPS IN THE CHANCE CATEGORY FOR NOW.
TEMPERATURES WEDNESDAY WILL ONCE AGAIN CLIMB TO WELL ABOVE NORMAL
WITH HIGHS APPROACHING 40 DEGREES IN THE SOUTHERN VALLEY...SO
INITIAL PRECIPITATION PHASE MAY BE A RAIN/SNOW MIX OR ALL RAIN.
MODELS ARE IN POOR AGREEMENT THURSDAY AND THURSDAY NIGHT WITH THE
GFS DRY AND THE ECMWF/GEM/NAM BRINGING ANOTHER BAND OF LIGHT SNOW
ACROSS THE REGION LATE IN THE DAY. WILL KEEP CHANCE POPS
GOING...BUT ADJUSTMENTS WILL BE NEEDED ONCE MODELS COME INTO
BETTER AGREEMENT. TEMPERATURES WILL DROP SOME ON THURSDAY...BUT
STILL REMAIN ABOVE LATE-DECEMBER NORMALS WITH HIGHS IN THE MID 20S
TO MID 30S.
LONG TERM...FRIDAY THROUGH MONDAY NIGHT
WILL CONTINUE TO KEEP THE 20-30 POPS WE HAVE GOING FOR FRIDAY...
AS ALL DETERMINISTIC MODELS ARE IN PRETTY GOOD AGREEMENT ON
BREAKING OUT SOME PRECIP AS A WEAK SHORTWAVE MOVES THROUGH THE
AREA. A MORE SIGNIFICANT WAVE APPROACHES THE AREA ON SATURDAY...
AND THERE IS SOME VARIATION ON HOW FAST THE MODELS BRING THE
SYSTEM THROUGH. THE ECMWF CLOSES OFF A LOW AND IS MUCH SLOWER THAN
THE GFS AND GEM...WHICH BRING A COLD FRONT THROUGH FAIRLY EARLY ON
THE DAY ON SATURDAY. THE ECMWF CONTINUES WITH WARM AIR ADVECTION
IN SATURDAY AFTERNOON. ENSEMBLE SPREAD IS PRETTY HIGH WITH THE
SYSTEM...BUT THE GFS ENSEMBLE MEAN HAS SOME WARMER TEMPS IN THE
SOUTHERN CWA LIKE THE OPERATIONAL ECMWF. BUMPED UP TEMPS A BIT IN
THE SOUTHERN COUNTIES...AND INCLUDED A MIX OF RAIN AND SNOW
MENTION. MODEL CONSENSUS GOES FURTHER DOWNHILL ON DAYS 6 AND
7...WITH THE GFS AND GEM SETTING UP NEAR ZONAL FLOW AND THE ECMWF
BECOMING VERY MERIDIONAL AS THE UPPER TROUGH DIGS INTO THE GREAT
LAKES. WENT WITH THE COMPROMISE ALLBLEND AND WILL CONTINUE TO KEEP
SOME LOW POPS IN THE NORTH AND EAST FOR SUNDAY IN CASE THE SLOWER
ECMWF VERIFIES...BUT KEPT TEMPS WARMER THAN THE NORTHERLY FLOW OF
THE ECMWF WOULD INDICATE.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
SPEICHER/EWENS
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
614 AM CST TUE DEC 27 2011
.UPDATE...
MAIN AREA OF MODERATE RAINFALL HAS MOVED NORTHEAST OF MID STATE
THIS MORNING. SHORT RANGE/HRRR MODELS ALSO SHOWING THAT SHWRS WILL
CONTINUE TO OCCUR...NOT STEADILY...BUT AT IRREGULAR INTERVALS...AS
SFC/UPPER LEVEL TROUGH MOVES TO THE NE THRU THE MORNING HRS. THUS...
WILL UPDATE THE SUITE OF FORECAST PRODUCTS TO REFLECT INTERMITTENT
SHWRS ALL AREAS THRU THE MORNING HRS.
&&
.PREV DISCUSSION.../ISSUED 523 AM CST TUE DEC 27 2011/
UPDATE...FOR AVIATION.
AVIATION...
12Z TAFS...LOW PRESSURE NEAR CKV WILL DEEPEN AS IT MOVES NORTHEAST
ACROSS KY TODAY. INCREASING PRESSURE GRADIENT WILL CAUSE GUSTY
WINDS TO 25KT OR SO TO DEVELOP...FROM THE SW THIS MORNING...THEN
BECOMING WNW. SCATTERED SHOWERS WILL OCCUR MAINLY THIS MORNING
WITH SOME MVFR VSBYS. CIGS WILL BE MAINLY IFR THROUGH THE MORNING.
BNA WILL IMPROVE TO MVFR IN THE AFTERNOON AND VFR TONIGHT. CSV
WILL HOVER FROM IFR TO MVFR THROUGH THE PERIOD.
13
PREV DISCUSSION... /ISSUED 333 AM CST TUE DEC 27 2011/
DISCUSSION...
FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION
COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED.
MAIN FORECAST QUANDARIES...ACTUAL TIMING OF RAINFALL ENDING W TO
E AND STRENGTH OF WINDS TODAY...POSSIBLE RAIN/SNOW MIX PLATEAU
THIS EVENING...TEMPS...AND OVERALL FORECAST EARLY NEXT WEEK.
AS FOR TODAY...AS OF 09Z...WIDE SWATH OF LIGHT TO MODERATE SHWRS
MOVING GENERALLY S TO N ACROSS MID STATE ACROSS LOCATIONS GENERALLY
ALONG AND E OF I-65. SOME BREAKS IN RAINFALL NOTED W OF THIS AREA...
BUT SHWRS DEVELOPING IN VICINITY OF UPPER LEVEL LOW ACROSS W TN
AND ERN AK. ALL OF THIS AS SFC LOW CONTINUES TO MOVE ACROSS W
TN...WITH UPPER LEVEL TROUGH BEGINNING TO MOVE INTO FAR WRN PORTIONS
OF THE STATE. WILL BE MAKING FINAL DECISION AT PRESS TIME...BUT
AM LEANING TOWARD DEF SHWRS GENERALLY E OF I-65 TO NUMEROUS SHWRS
W...TRANSITIONING TO NUMEROUS TO SCATTERED LIGHT SHWRS ALL
LOCATIONS EXPECT THOSE CLOSE TO AND ACROSS THE CUMBERLAND PLATEAU
REGION DURING THE LATER MORNING HRS.
THIS AFTERNOON THE MID STATE SHOULD EXPERIENCE AREAS ACROSS WRN
MIDDLE TN FINALLY BECOME DRY NEAR AND JUST EAST OF THE TN RIVER
VALLEY REGION...WITH ISO/SCT LIGHT SHWRS ACROSS THE REMAINDER OF
THE MID STATE DURING THE AFTERNOON HRS. THIS REASONING BASED ON
THE FACT THAT THE SFC LOW AND UPPER LEVEL TROUGH WILL CONTINUE TO
MOVE NEWD OVER TIME WITH CLDY SKIES ACROSS MOST LOCATIONS THRU THE
AFTERNOON HRS. HRRR MODEL HINTING AT THE POTENTIAL FOR A RAIN/SNOW
MIX ACROSS FAR NW PORTIONS OF THE MID STATE BY THE EARLY AFTERNOON
HRS...BUT WITH TEMPS EXPECTED TO REMAIN VERY CLOSE TO CURRENT
TEMPS IN THE LOWER 40S THRU THE AFTERNOON HRS...WILL NOT MENTION
IN THE SUITE OF FORECAST PRODUCTS AS OF THIS TIME. DO NOT EXPECT
OTHER LOCATIONS ACROSS THE MID STATE TO DEVIATE MUCH FROM CURRENT
TEMPS BEING EXPERIENCED.
AS THIS SYSTEM MOVES NEWD...EXPECT SOME MIXING DOWN OF 30 TO 40
MPH 925MB WINDS TO THE SFC DURING THE AFTERNOON HRS. DO NOT EXPECT
ANY LOCATION ACROSS THE MID STATE TO REACH WIND ADVISORY CRITERIA
AS OF THIS TIME...BUT WOULD NOT BE SURPRISED THAT SOME LOCATIONS
EXPERIENCE GUSTS OF 25 TO 30 MPH LATER THIS AFTERNOON.
AS FOR TONIGHT...THERE MIGHT BE A SLIGHT CHANCE OF A RAIN/SNOW
MIXTURE ACROSS NRN PORTIONS OF THE CUMBERLAND PLATEAU DURING THE
EARLY EVENING HRS AS MOISTURE ASSOCIATED WITH UPPER LEVEL TROUGH
MOVES ACROSS THIS PART OF THE MID STATE AND WITH TEMPS EXPECTED
TO FALL INTO THE UPPER TO MID 30S. HOWEVER...AS OF THIS TIME...NO
ACCUMULATION IS EXPECTED. OTHERWISE...LOOK FOR A SLOW DECREASE IN
CLOUDINESS W TO E ACROSS THE MID STATE...WITH DRY CONDITIONS...AND
LOWS NEAR NORMAL VALUES FOR THIS TIME OF YEAR...AROUND 30...UPPER
20S PLATEAU.
AS FOR WED...A WEAK SHORTWAVE PASSAGE IS EXPECTED ACROSS THE SRN OHIO
VALLEY AND PORTIONS OF KY DURING THE AFTERNOON HRS...WHICH MIGHT BRING
SOME ADDITIONAL CLOUDINESS TO LOCATIONS APPROACHING THE TN/KY BORDER.
HOWEVER...AT THIS TIME...WILL GO WITH PTCDLY SKIES ACROSS THE ENTIRE MID
STATE...WITH AFTERNOON HIGH TEMPS GETTING BACK CLOSE TO CLIMATOLOGICAL
NORMS...WITH HIGHS IN THE MID 40S N TO UPPER 40S S...LOW 40S PLATEAU.
AS FOR WED NIGHT...SKIES SHOULD EVENTUALLY BECOME MOCLR BY LATE WED
NIGHT...WITH LOWS AGAIN IN THE LOWER 30S...UPPER 20S PLATEAU.
AS FOR THU...AS HIGH SHIFTS EWD...AND MORE OF A SLY SFC FLOW DEVELOPS
ACROSS THE MID STATE...HIGHS SHOULD WARM UP INTO THE LOWER TO MID 50S...
WITH PTCLDY SKIES AND DRY CONDITIONS.
AS FOR THE REST OF THE FORECAST PERIOD...WILL KEEP IT DRY THRU NEW
YEARS DAY...WHEN THE NEXT CHANCE OF RAINFALL ACROSS THE MID STATE
WILL OCCUR AS ANOTHER COLD FRONT IS EXPECTED TO MOVE ACROSS THE
MID STATE. INTO THE FIRST HALF OF NEXT WEEK THOUGH...SIGNIFICANT
MODEL DIFFERENCES ARE OCCURRING. THE GFS BEING THE DRIER AND
WARMER SOLUTION AND THE EURO BEING THE COLDER AND WETTER SOLUTION.
AM GOING TO PLAY IT MIDDLE OF THE ROAD HERE...AND GO WITH A DRY
FORECAST...A LEAN MORE TOWARD THE GFS...AS I AM A LITTLE WEARY OF
THE VERY PROGRESSIVE AND DEEP UPPER LEVEL LOW AND TROUGH SOLUTION
THAT THE EURO IS ADVERTISING ACROSS THE MID SOUTH NEXT TUE INTO
WED. THRU THIS PERIOD...AFTERNOON HIGH TEMPS WILL MAINLY BE IN THE
50S...WITH OVERNIGHT LOWS...EXPECT FOR SAT NIGHT WHICH WILL BE IN
THE MID 40S...MAINLY IN THE 30S.
31
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
31
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
523 AM CST TUE DEC 27 2011
.UPDATE...FOR AVIATION.
&&
.AVIATION...
12Z TAFS...LOW PRESSURE NEAR CKV WILL DEEPEN AS IT MOVES NORTHEAST
ACROSS KY TODAY. INCREASING PRESSURE GRADIENT WILL CAUSE GUSTY
WINDS TO 25KT OR SO TO DEVELOP...FROM THE SW THIS MORNING...THEN
BECOMING WNW. SCATTERED SHOWERS WILL OCCUR MAINLY THIS MORNING
WITH SOME MVFR VSBYS. CIGS WILL BE MAINLY IFR THROUGH THE MORNING.
BNA WILL IMPROVE TO MVFR IN THE AFTERNOON AND VFR TONIGHT. CSV
WILL HOVER FROM IFR TO MVFR THROUGH THE PERIOD.
13
&&
.PREV DISCUSSION... /ISSUED 333 AM CST TUE DEC 27 2011/
DISCUSSION...
FORECAST REASONING WILL LEAN TOWARD A CONSENSUS MODEL SOLUTION
COMPROMISE FOR THE FORECAST PERIOD UNLESS OTHERWISE NOTED.
MAIN FORECAST QUANDARIES...ACTUAL TIMING OF RAINFALL ENDING W TO
E AND STRENGTH OF WINDS TODAY...POSSIBLE RAIN/SNOW MIX PLATEAU
THIS EVENING...TEMPS...AND OVERALL FORECAST EARLY NEXT WEEK.
AS FOR TODAY...AS OF 09Z...WIDE SWATH OF LIGHT TO MODERATE SHWRS
MOVING GENERALLY S TO N ACROSS MID STATE ACROSS LOCATIONS GENERALLY
ALONG AND E OF I-65. SOME BREAKS IN RAINFALL NOTED W OF THIS AREA...
BUT SHWRS DEVELOPING IN VICINITY OF UPPER LEVEL LOW ACROSS W TN
AND ERN AK. ALL OF THIS AS SFC LOW CONTINUES TO MOVE ACROSS W
TN...WITH UPPER LEVEL TROUGH BEGINNING TO MOVE INTO FAR WRN PORTIONS
OF THE STATE. WILL BE MAKING FINAL DECISION AT PRESS TIME...BUT
AM LEANING TOWARD DEF SHWRS GENERALLY E OF I-65 TO NUMEROUS SHWRS
W...TRANSITIONING TO NUMEROUS TO SCATTERED LIGHT SHWRS ALL
LOCATIONS EXPECT THOSE CLOSE TO AND ACROSS THE CUMBERLAND PLATEAU
REGION DURING THE LATER MORNING HRS.
THIS AFTERNOON THE MID STATE SHOULD EXPERIENCE AREAS ACROSS WRN
MIDDLE TN FINALLY BECOME DRY NEAR AND JUST EAST OF THE TN RIVER
VALLEY REGION...WITH ISO/SCT LIGHT SHWRS ACROSS THE REMAINDER OF
THE MID STATE DURING THE AFTERNOON HRS. THIS REASONING BASED ON
THE FACT THAT THE SFC LOW AND UPPER LEVEL TROUGH WILL CONTINUE TO
MOVE NEWD OVER TIME WITH CLDY SKIES ACROSS MOST LOCATIONS THRU THE
AFTERNOON HRS. HRRR MODEL HINTING AT THE POTENTIAL FOR A RAIN/SNOW
MIX ACROSS FAR NW PORTIONS OF THE MID STATE BY THE EARLY AFTERNOON
HRS...BUT WITH TEMPS EXPECTED TO REMAIN VERY CLOSE TO CURRENT
TEMPS IN THE LOWER 40S THRU THE AFTERNOON HRS...WILL NOT MENTION
IN THE SUITE OF FORECAST PRODUCTS AS OF THIS TIME. DO NOT EXPECT
OTHER LOCATIONS ACROSS THE MID STATE TO DEVIATE MUCH FROM CURRENT
TEMPS BEING EXPERIENCED.
AS THIS SYSTEM MOVES NEWD...EXPECT SOME MIXING DOWN OF 30 TO 40
MPH 925MB WINDS TO THE SFC DURING THE AFTERNOON HRS. DO NOT EXPECT
ANY LOCATION ACROSS THE MID STATE TO REACH WIND ADVISORY CRITERIA
AS OF THIS TIME...BUT WOULD NOT BE SURPRISED THAT SOME LOCATIONS
EXPERIENCE GUSTS OF 25 TO 30 MPH LATER THIS AFTERNOON.
AS FOR TONIGHT...THERE MIGHT BE A SLIGHT CHANCE OF A RAIN/SNOW
MIXTURE ACROSS NRN PORTIONS OF THE CUMBERLAND PLATEAU DURING THE
EARLY EVENING HRS AS MOISTURE ASSOCIATED WITH UPPER LEVEL TROUGH
MOVES ACROSS THIS PART OF THE MID STATE AND WITH TEMPS EXPECTED
TO FALL INTO THE UPPER TO MID 30S. HOWEVER...AS OF THIS TIME...NO
ACCUMULATION IS EXPECTED. OTHERWISE...LOOK FOR A SLOW DECREASE IN
CLOUDINESS W TO E ACROSS THE MID STATE...WITH DRY CONDITIONS...AND
LOWS NEAR NORMAL VALUES FOR THIS TIME OF YEAR...AROUND 30...UPPER
20S PLATEAU.
AS FOR WED...A WEAK SHORTWAVE PASSAGE IS EXPECTED ACROSS THE SRN OHIO
VALLEY AND PORTIONS OF KY DURING THE AFTERNOON HRS...WHICH MIGHT BRING
SOME ADDITIONAL CLOUDINESS TO LOCATIONS APPROACHING THE TN/KY BORDER.
HOWEVER...AT THIS TIME...WILL GO WITH PTCDLY SKIES ACROSS THE ENTIRE MID
STATE...WITH AFTERNOON HIGH TEMPS GETTING BACK CLOSE TO CLIMATOLOGICAL
NORMS...WITH HIGHS IN THE MID 40S N TO UPPER 40S S...LOW 40S PLATEAU.
AS FOR WED NIGHT...SKIES SHOULD EVENTUALLY BECOME MOCLR BY LATE WED
NIGHT...WITH LOWS AGAIN IN THE LOWER 30S...UPPER 20S PLATEAU.
AS FOR THU...AS HIGH SHIFTS EWD...AND MORE OF A SLY SFC FLOW DEVELOPS
ACROSS THE MID STATE...HIGHS SHOULD WARM UP INTO THE LOWER TO MID 50S...
WITH PTCLDY SKIES AND DRY CONDITIONS.
AS FOR THE REST OF THE FORECAST PERIOD...WILL KEEP IT DRY THRU NEW
YEARS DAY...WHEN THE NEXT CHANCE OF RAINFALL ACROSS THE MID STATE
WILL OCCUR AS ANOTHER COLD FRONT IS EXPECTED TO MOVE ACROSS THE
MID STATE. INTO THE FIRST HALF OF NEXT WEEK THOUGH...SIGNIFICANT
MODEL DIFFERENCES ARE OCCURRING. THE GFS BEING THE DRIER AND
WARMER SOLUTION AND THE EURO BEING THE COLDER AND WETTER SOLUTION.
AM GOING TO PLAY IT MIDDLE OF THE ROAD HERE...AND GO WITH A DRY
FORECAST...A LEAN MORE TOWARD THE GFS...AS I AM A LITTLE WEARY OF
THE VERY PROGRESSIVE AND DEEP UPPER LEVEL LOW AND TROUGH SOLUTION
THAT THE EURO IS ADVERTISING ACROSS THE MID SOUTH NEXT TUE INTO
WED. THRU THIS PERIOD...AFTERNOON HIGH TEMPS WILL MAINLY BE IN THE
50S...WITH OVERNIGHT LOWS...EXPECT FOR SAT NIGHT WHICH WILL BE IN
THE MID 40S...MAINLY IN THE 30S.
31
&&
.OHX 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 LA CROSSE WI
1132 AM CST TUE DEC 27 2011
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
305 AM CST TUE DEC 27 2011
MAIN FORECAST CONCERN IS ON LOW PRECIPITATION CHANCES THROUGHOUT THE
SHORT TERM PERIOD.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED A SHORTWAVE TROUGH OVER BRITISH COLUMBIA...WEAK RIDGING OVER
THE SOUTHWEST U.S. INTO ALBERTA AND SASKATCHEWAN...AN UPPER TROUGH
OVER MINNESOTA AND AN UPPER LOW OVER NORTHERN MISSISSIPPI. THE
UPPER TROUGH IS GRADUALLY BRINGING COLDER AIR INTO THE UPPER
MISSISSIPPI RIVER VALLEY REGION...NOTED BY 850MB TEMPS THAT FELL
BETWEEN 12Z YESTERDAY AND 00Z TODAY FROM 4C TO 1C AT MPX...AND 6 TO
-2C AT BIS. MORE COLD AIR LURKS FARTHER UPSTREAM WITH -12C REPORTED
AT THE PAS MANITOBA. MID TO UPPER LEVEL DYNAMIC LIFT WITH THE TROUGH
IS FAIRLY WEAK AND MOSTLY OFF TO THE EAST OVER LAKE MICHIGAN...PER
QG APPEARANCE FROM THE RUC/ECMWF. THIS LIFT IS WHAT HELPED PRODUCE
THE RAIN/SLEET/SNOW LAST EVENING. BIGGER ISSUE WITH THE UPPER TROUGH
IS ACTUALLY THE SUBSIDENCE AND THE COLD ADVECTION...WHICH IS HELPING
TO PRODUCE 15-20 KT SURFACE SUSTAINED WINDS AND GUSTS TO 30 KT
ACROSS MUCH OF MINNESOTA. THESE ARE OCCURRING IN THE WAKE OF TWO
COLD FRONTS: THE FIRST SITUATED NORTH-SOUTH OVER CENTRAL WISCONSIN
AND THE SECOND ALIGNED WEST EAST FROM ABERDEEN SOUTH DAKOTA INTO
UPPER MICHIGAN. A LARGE AMOUNT OF STRATUS EXISTS BEHIND THESE
FRONTS...WITH THE LOWEST CEILINGS BEHIND THE SECONDARY FRONT WHERE A
GREATER SURGE OF COLD AIR ADVECTION IS HELPING TO UNDERCUT LOW LEVEL
MOISTURE. A FEW FLURRIES ALSO OCCURRING FROM THE STRATUS.
TODAY AND TONIGHT...MODELS PROG THE UPPER TROUGH OVER MINNESOTA TO
MOVE RAPIDLY TO THE EAST...IN RESPONSE TO FAST FLOW COMING OFF THE
PACIFIC. BY MIDNIGHT TONIGHT...THE UPSTREAM WEAK RIDGING SHOULD HAVE
MOVED INTO THE FORECAST AREA. THIS SITUATION MEANS THAT THE CURRENT
STRATUS AND STRONGER WINDS MOVING INTO THE FORECAST AREA FROM
MINNESOTA WILL NOT STAY AROUND LONG. IN FACT...GOOD MODEL AGREEMENT
EXISTS THAT SKIES SHOULD CLEAR OUT ACROSS MINNESOTA AND IOWA BETWEEN
18-21Z TODAY. ON THE OTHER HAND...OVER WISCONSIN...THERE ARE
SUGGESTIONS BY THE 27.00Z NAM/27.03Z RUC THAT THE STRATUS MAY LINGER
THROUGH THE EVENING BEFORE DISSIPATING AFTER MIDNIGHT (PER 925MB RH
DATA). THIS CERTAINLY SEEMS PLAUSIBLE...SINCE STRATUS TYPICALLY
LINGERS LONGER THAN ONE WOULD EXPECT THIS TIME OF YEAR. ALSO...THERE
SHOULD BE A GOOD TRANSPORT OF MOISTURE OFF LAKE SUPERIOR GIVEN
COLDER AIR FLOWING SOUTH. THEREFORE...HAVE RAISED SKY COVER VALUES
OVER WISCONSIN FOR THIS EVENING. REGARDING PRECIP CHANCES WITH THE
STRATUS...ANY LIFT IS VERY WEAK...ASSOCIATED WITH LOW LEVEL
FRONTOGENESIS. GIVEN OVERALL LACK OF PRECIPITATION RIGHT NOW ON
RADAR...ONLY WENT WITH FLURRIES THIS MORNING. DRYING TREND SHOWING
UP NOW IN THE HRRR RUNS WOULD AGREE WITH THIS AS WELL. AFTER THAT...
SUBSIDENCE TAKING HOLD SHOULD SHUT OFF ANY PRECIPITATION ACTION.
LOOKING AHEAD TO AFTER MIDNIGHT TONIGHT...SHORTWAVE TROUGH OVER
BRITISH COLUMBIA ALONG WITH A WEAKER SHORTWAVE CURRENTLY SEEN OVER
IDAHO ARE FORECAST TO BEGIN TO DROP DOWN INTO MINNESOTA AROUND 12Z
TUESDAY. WARM ADVECTION AHEAD OF THESE SHOULD RESULT IN A MID CLOUD
DECK OF STRATUS...WHILE ANY PRECIPITATION STAYS NORTHWEST OF THE
FORECAST AREA. REGARDING TEMPERATURES...WITH COLD ADVECTION
OCCURRING TODAY NOTED BY 850MB TEMPS FALLING TO -5 TO -8C BY
18Z...ANTICIPATING GENERALLY STEADY OR FALLING TEMPERATURES. TONIGHT
IS A LITTLE TRICKY WITH STRATUS OVER WISCONSIN AND THEN CLOUDS
COMING IN AFTER MIDNIGHT EVERYWHERE. FOR NOW HAVE FOLLOWED A BLEND
OF GUIDANCE FOR LOWS.
WEDNESDAY AND WEDNESDAY NIGHT...SHORTWAVE OVER MINNESOTA AT 12Z
WEDNESDAY IS FORECAST TO SHIFT EAST FAIRLY QUICKLY...REACHING LOWER
MICHIGAN BY 00Z THURSDAY. BIGGEST CONCERN WITH THIS SHORTWAVE IS
POTENTIAL FOR SOME WARM ADVECTION LIGHT SNOW SKIRTING TAYLOR AND
CLARK COUNTIES. THE 00Z NAM/26.21Z SREF SUGGEST THIS IS POSSIBLE...
WHEREAS THE 27.00Z GFS/26.12Z ECMWF ARE DRY. GIVEN THE WAY RECENT
SYSTEMS HAVE GONE...WITH LIGHT PRECIPITATION HAPPENING DESPITE
PRESENCE OF LOW LEVEL DRY AIR...FEEL COMPELLED TO AT LEAST PLACE A 20
PERCENT CHANCE IN TAYLOR AND CLARK COUNTIES. ELSEWHERE...A
DECREASING CLOUD TREND SHOULD OCCUR WITH TEMPERATURES CLIMBING INTO
THE 30S. COULD SEE READINGS PUSH 40 IN FAR WESTERN AREAS. FOR
WEDNESDAY NIGHT...ATTENTION RE-FOCUSES TO THE NORTHWEST WHERE MODELS
SHOW A DECENT SHORTWAVE MOVING THROUGH A FAST WEST-NORTHWEST UPPER
LEVEL FLOW. AT 00Z...MODELS SUGGEST IT IS EITHER OVER EASTERN
MONTANA OR SOUTHEAST SASKATCHEWAN...THEN IT MARCHES SOUTHEAST INTO
THE FORECAST AREA AROUND 12Z THURSDAY. AS FAR AS WHERE IN THE
FORECAST AREA...THIS VARIES GREATLY...SO FOR NOW HAVE TAKEN A BLEND
APPROACH GIVEN THE FAST FLOW. AS THE SHORTWAVE APPROACHES...SHOULD
SEE MID AND HIGH CLOUDS DEVELOP IN RESPONSE TO WARM ADVECTION AND
DPVA FORCING. LIGHT PRECIPITATION COULD EVEN START BREAKING OUT IN
NORTHWESTERN PORTIONS OF THE AREA IN THE EVENING. AFTER MIDNIGHT...
ANTICIPATING SOME LIGHT PRECIPITATION EVERYWHERE. PRECIPITATION
CHANCES REMAIN IN THE 20 TO 30 RANGE...HOWEVER...DUE TO THE LARGE
SPREAD IN TRACK OF THE SHORTWAVE. ENVISION CHANCES NEEDING A BUMP
UP IN LATER FORECASTS...BUT WHERE IS THE QUESTION. WITH THE CLOUDS
MOVING IN...NOT ANTICIPATING AS MUCH OF A TEMPERATURE FALL AS
TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR LOWS.
THURSDAY AND THURSDAY NIGHT...SIMILAR TO THE PAST FEW DAYS...THE
PARADE OF SHORTWAVES FROM THE PACIFIC CONTINUE TO COME THROUGH THE
FAST FLOW. SHORTWAVE THAT IS NEAR/OVER THE AREA AT 12Z THURSDAY IS
PROGGED TO REACH LOWER MICHIGAN BY 00Z...WHILE ANOTHER SHORTWAVE
MOVES INTO THE DAKOTAS. SHOULD SEE THE PRECIPITATION DIMINISH FOR A
TIME THURSDAY...ESPECIALLY IN THE AFTERNOON NORTH OF I-90 AS THAT
AREA GETS INTO THE SUBSIDENCE BEHIND THE MORNING SHORTWAVE. DURING
THE AFTERNOON...PRECIPITATION IS POSSIBLE SOUTH OF I-90 AS WARM
ADVECTION OCCURS DOWNSTREAM OF THE SHORTWAVE ENTERING THE DAKOTAS.
WITH UNCERTAINTY ON THE PLACEMENT OF THE SHORTWAVE NEAR/OVER THE
AREA AT 12Z THURSDAY...ALONG WITH SUGGESTIONS OF LOW LEVEL DRY AIR
TO OVERCOME IN SOUNDINGS...HAVE KEPT PRECIPITATION CHANCES BETWEEN
20 AND 30. A LOT OF UNCERTAINTY EXISTS WITH THIS DAKOTAS SHORTWAVE
HEADING INTO THURSDAY NIGHT...WHERE THE 27.00Z ECMWF/UKMET DROP IT
DOWN INTO MISSOURI WHEREAS THE 27.00Z GFS CROSSES IOWA AND THE
27.00Z NAM CROSSES THE FORECAST AREA. FEELING IS THE SOUTHERN
SOLUTIONS MAY HAVE A BETTER CHANCE OF VERIFYING...DUE TO THE USUAL
BETTER PREDICTABILITY OF THE ECMWF...BUT NOT COMPLETELY SURE GIVEN
THE FAST FLOW. THEREFORE...20 TO 30 PERCENT CHANCES CONTINUE FOR
THURSDAY NIGHT. WITH SO MUCH UNCERTAINTY ON THE TRACKS OF THESE
SHORTWAVES...TEMPERATURE FORECASTS ARE PROBLEMATIC. CERTAINLY
POTENTIAL EXISTS ON THURSDAY FOR AT LEAST THE SOUTHERN PORTION OF
THE AREA TO HIT 40 OR HIGHER...ESPECIALLY IF THE SHORTWAVE THEN
TRACKS FARTHER NORTH. CLOUDS THURSDAY NIGHT SHOULD HOLD TEMPERATURES
UP IN THE 20S TO LOW 30S...COLDEST IN TAYLOR AND CLARK COUNTIES
WHERE COOLER AIR SINKS SOUTH BEHIND THE SHORTWAVE MOSTLY SUGGESTED
TO TRACK NEAR OR SOUTH OF THE AREA.
.LONG TERM...FRIDAY THROUGH MONDAY NIGHT
305 AM CST TUE DEC 27 2011
27.00Z MODEL CYCLE CONSISTING OF THE ECMWF/GFS/CANADIAN AND GFS
ENSEMBLES STILL PRESENT PLENTY OF UNCERTAINTY WITH REGARDS TO THE
UPPER LEVEL PATTERN THROUGHOUT THE LONG TERM PERIOD...THOUGH THERE
ARE SOME FEATURES THAT CAN BE LATCHED ONTO. THE FIRST IS A FAIRLY
POTENT SHORTWAVE TROUGH POISED TO COME INTO THE PACIFIC NORTHWEST ON
FRIDAY...RESULTING IN BUILDING RIDGING DOWNSTREAM TOWARDS THE
FORECAST AREA. THIS RIDGING LOOKS TO BUILD INTO THE AREA FRIDAY
NIGHT...BRINGING IN A SURGE OF DOWNSLOPED PACIFIC AIR. TIMING THE
PACIFIC NORTHWEST SHORTWAVE TROUGH AND INTENSITY WILL BE CRITICAL IN
DETERMINING HOW WARM NEW YEARS EVE IS. LOOKS LIKE THERE SHOULD BE
SOME WARM ADVECTION PRECIPITATION DOWNSTREAM INTO THE AREA
FRIDAY/FRIDAY NIGHT...BUT THIS MOSTLY LIFTS NORTH ON NEW YEARS EVE.
THE 26.12Z/27.00Z ECMWF RUNS ARE BY FAR THE MOST AMPLIFIED...
RESULTING IN A SLOWER COLD FRONTAL PASSAGE AND HIGH TEMPERATURES
SATURDAY FROM THE 40S INTO THE LOW 50S. FOR NOW HAVE TAKEN A 30 DAY
BIAS CORRECTION OF THE CONSENSUS OF ALL GUIDANCE...WHICH RESULTS IN
HIGHS MOSTLY IN THE 40S. CERTAINLY POTENTIAL EXISTS FOR WARMER
READINGS GIVEN LACK OF SNOW COVER STILL ANTICIPATED. COLDER AIR WILL
MOVE INTO THE AREA FOR NEW YEARS DAY AS THE UPPER TROUGH MOVES
IN...BUT HOW MUCH DEPENDS ON THE PROGRESSIVE NATURE OF THE UPPER
TROUGH. THE MORE AMPLIFIED ECMWF BASICALLY TURNS THE TROUGH INTO A
LONGWAVE TROUGH...ALLOWING FOR AIR OF MORE ARCTIC ORIGIN TO FLOW
SOUTH INTO THE AREA FOR NEW YEARS DAY AND MONDAY. ON THE OTHER
HAND...THE 27.00Z GFS/CANADIAN DEPICT MUCH MORE PROGRESSION...
RESULTING IN A CONTINUED FEED OF PACIFIC AIR AND WARMER. GIVEN SO
MUCH UNCERTAINTY...A CONSENSUS OF GUIDANCE WAS FOLLOWED FOR NEW
YEARS DAY THROUGH MONDAY NIGHT. IN EITHER MODEL CAMP SCENARIO...IT
LOOKS LIKE LITTLE IF ANY PRECIPITATION WILL OCCUR.
&&
.AVIATION...THROUGH 18Z WEDNESDAY
1131 AM CST TUE DEC 27 2011
WINDS WILL GRADUALLY DIMINISH THIS AFTERNOON AS HIGH PRESSURE
BUILDS INTO THE REGION. LOOK FOR NORTHEAST WINDS AT 15 TO 20 KTS
GUSTING TO AROUND 27 KTS EARLY THIS AFTERNOON...THEN DECREASING
INTO THE 10 TO 13 KT RANGE AS THE HIGH EDGES INTO THE AREA. MVFR
CEILINGS WILL IMPROVE TO VFR THIS AFTERNOON...WITH A FEW LINGERING
CUMULUS IN THE AREA...WITH CLOUD BASES AROUND 2 KFT. A SHORTWAVE
TROUGH IS EXPECTED TO MOVE ACROSS THE DAKOTAS AND INTO THE AREA
TONIGHT...SPREADING MID LEVEL CLOUDS ACROSS THE AREA. LOOK FOR
CLOUD BASES IN THE 5 TO 8 KFT RANGE AS THE TROUGH MOVES THROUGH.
VFR CONDITIONS WILL PERSIST OVERNIGHT INTO WEDNESDAY MORNING.
LIGHT AND VARIABLE WINDS OVERNIGHT WILL BECOME SOUTH LATE
WEDNESDAY MORNING IN THE 10 TO 15 KT RANGE.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST TUE DEC 27 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
521 AM CST TUE DEC 27 2011
.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
305 AM CST TUE DEC 27 2011
MAIN FORECAST CONCERN IS ON LOW PRECIPITATION CHANCES THROUGHOUT THE
SHORT TERM PERIOD.
CURRENTLY AS OF 08Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED A SHORTWAVE TROUGH OVER BRITISH COLUMBIA...WEAK RIDGING OVER
THE SOUTHWEST U.S. INTO ALBERTA AND SASKATCHEWAN...AN UPPER TROUGH
OVER MINNESOTA AND AN UPPER LOW OVER NORTHERN MISSISSIPPI. THE
UPPER TROUGH IS GRADUALLY BRINGING COLDER AIR INTO THE UPPER
MISSISSIPPI RIVER VALLEY REGION...NOTED BY 850MB TEMPS THAT FELL
BETWEEN 12Z YESTERDAY AND 00Z TODAY FROM 4C TO 1C AT MPX...AND 6 TO
-2C AT BIS. MORE COLD AIR LURKS FARTHER UPSTREAM WITH -12C REPORTED
AT THE PAS MANITOBA. MID TO UPPER LEVEL DYNAMIC LIFT WITH THE TROUGH
IS FAIRLY WEAK AND MOSTLY OFF TO THE EAST OVER LAKE MICHIGAN...PER
QG APPEARANCE FROM THE RUC/ECMWF. THIS LIFT IS WHAT HELPED PRODUCE
THE RAIN/SLEET/SNOW LAST EVENING. BIGGER ISSUE WITH THE UPPER TROUGH
IS ACTUALLY THE SUBSIDENCE AND THE COLD ADVECTION...WHICH IS HELPING
TO PRODUCE 15-20 KT SURFACE SUSTAINED WINDS AND GUSTS TO 30 KT
ACROSS MUCH OF MINNESOTA. THESE ARE OCCURRING IN THE WAKE OF TWO
COLD FRONTS: THE FIRST SITUATED NORTH-SOUTH OVER CENTRAL WISCONSIN
AND THE SECOND ALIGNED WEST EAST FROM ABERDEEN SOUTH DAKOTA INTO
UPPER MICHIGAN. A LARGE AMOUNT OF STRATUS EXISTS BEHIND THESE
FRONTS...WITH THE LOWEST CEILINGS BEHIND THE SECONDARY FRONT WHERE A
GREATER SURGE OF COLD AIR ADVECTION IS HELPING TO UNDERCUT LOW LEVEL
MOISTURE. A FEW FLURRIES ALSO OCCURRING FROM THE STRATUS.
TODAY AND TONIGHT...MODELS PROG THE UPPER TROUGH OVER MINNESOTA TO
MOVE RAPIDLY TO THE EAST...IN RESPONSE TO FAST FLOW COMING OFF THE
PACIFIC. BY MIDNIGHT TONIGHT...THE UPSTREAM WEAK RIDGING SHOULD HAVE
MOVED INTO THE FORECAST AREA. THIS SITUATION MEANS THAT THE CURRENT
STRATUS AND STRONGER WINDS MOVING INTO THE FORECAST AREA FROM
MINNESOTA WILL NOT STAY AROUND LONG. IN FACT...GOOD MODEL AGREEMENT
EXISTS THAT SKIES SHOULD CLEAR OUT ACROSS MINNESOTA AND IOWA BETWEEN
18-21Z TODAY. ON THE OTHER HAND...OVER WISCONSIN...THERE ARE
SUGGESTIONS BY THE 27.00Z NAM/27.03Z RUC THAT THE STRATUS MAY LINGER
THROUGH THE EVENING BEFORE DISSIPATING AFTER MIDNIGHT (PER 925MB RH
DATA). THIS CERTAINLY SEEMS PLAUSIBLE...SINCE STRATUS TYPICALLY
LINGERS LONGER THAN ONE WOULD EXPECT THIS TIME OF YEAR. ALSO...THERE
SHOULD BE A GOOD TRANSPORT OF MOISTURE OFF LAKE SUPERIOR GIVEN
COLDER AIR FLOWING SOUTH. THEREFORE...HAVE RAISED SKY COVER VALUES
OVER WISCONSIN FOR THIS EVENING. REGARDING PRECIP CHANCES WITH THE
STRATUS...ANY LIFT IS VERY WEAK...ASSOCIATED WITH LOW LEVEL
FRONTOGENESIS. GIVEN OVERALL LACK OF PRECIPITATION RIGHT NOW ON
RADAR...ONLY WENT WITH FLURRIES THIS MORNING. DRYING TREND SHOWING
UP NOW IN THE HRRR RUNS WOULD AGREE WITH THIS AS WELL. AFTER THAT...
SUBSIDENCE TAKING HOLD SHOULD SHUT OFF ANY PRECIPITATION ACTION.
LOOKING AHEAD TO AFTER MIDNIGHT TONIGHT...SHORTWAVE TROUGH OVER
BRITISH COLUMBIA ALONG WITH A WEAKER SHORTWAVE CURRENTLY SEEN OVER
IDAHO ARE FORECAST TO BEGIN TO DROP DOWN INTO MINNESOTA AROUND 12Z
TUESDAY. WARM ADVECTION AHEAD OF THESE SHOULD RESULT IN A MID CLOUD
DECK OF STRATUS...WHILE ANY PRECIPITATION STAYS NORTHWEST OF THE
FORECAST AREA. REGARDING TEMPERATURES...WITH COLD ADVECTION
OCCURRING TODAY NOTED BY 850MB TEMPS FALLING TO -5 TO -8C BY
18Z...ANTICIPATING GENERALLY STEADY OR FALLING TEMPERATURES. TONIGHT
IS A LITTLE TRICKY WITH STRATUS OVER WISCONSIN AND THEN CLOUDS
COMING IN AFTER MIDNIGHT EVERYWHERE. FOR NOW HAVE FOLLOWED A BLEND
OF GUIDANCE FOR LOWS.
WEDNESDAY AND WEDNESDAY NIGHT...SHORTWAVE OVER MINNESOTA AT 12Z
WEDNESDAY IS FORECAST TO SHIFT EAST FAIRLY QUICKLY...REACHING LOWER
MICHIGAN BY 00Z THURSDAY. BIGGEST CONCERN WITH THIS SHORTWAVE IS
POTENTIAL FOR SOME WARM ADVECTION LIGHT SNOW SKIRTING TAYLOR AND
CLARK COUNTIES. THE 00Z NAM/26.21Z SREF SUGGEST THIS IS POSSIBLE...
WHEREAS THE 27.00Z GFS/26.12Z ECMWF ARE DRY. GIVEN THE WAY RECENT
SYSTEMS HAVE GONE...WITH LIGHT PRECIPITATION HAPPENING DESPITE
PRESENCE OF LOW LEVEL DRY AIR...FEEL COMPELLED TO AT LEAST PLACE A 20
PERCENT CHANCE IN TAYLOR AND CLARK COUNTIES. ELSEWHERE...A
DECREASING CLOUD TREND SHOULD OCCUR WITH TEMPERATURES CLIMBING INTO
THE 30S. COULD SEE READINGS PUSH 40 IN FAR WESTERN AREAS. FOR
WEDNESDAY NIGHT...ATTENTION RE-FOCUSES TO THE NORTHWEST WHERE MODELS
SHOW A DECENT SHORTWAVE MOVING THROUGH A FAST WEST-NORTHWEST UPPER
LEVEL FLOW. AT 00Z...MODELS SUGGEST IT IS EITHER OVER EASTERN
MONTANA OR SOUTHEAST SASKATCHEWAN...THEN IT MARCHES SOUTHEAST INTO
THE FORECAST AREA AROUND 12Z THURSDAY. AS FAR AS WHERE IN THE
FORECAST AREA...THIS VARIES GREATLY...SO FOR NOW HAVE TAKEN A BLEND
APPROACH GIVEN THE FAST FLOW. AS THE SHORTWAVE APPROACHES...SHOULD
SEE MID AND HIGH CLOUDS DEVELOP IN RESPONSE TO WARM ADVECTION AND
DPVA FORCING. LIGHT PRECIPITATION COULD EVEN START BREAKING OUT IN
NORTHWESTERN PORTIONS OF THE AREA IN THE EVENING. AFTER MIDNIGHT...
ANTICIPATING SOME LIGHT PRECIPITATION EVERYWHERE. PRECIPITATION
CHANCES REMAIN IN THE 20 TO 30 RANGE...HOWEVER...DUE TO THE LARGE
SPREAD IN TRACK OF THE SHORTWAVE. ENVISION CHANCES NEEDING A BUMP
UP IN LATER FORECASTS...BUT WHERE IS THE QUESTION. WITH THE CLOUDS
MOVING IN...NOT ANTICIPATING AS MUCH OF A TEMPERATURE FALL AS
TONIGHT. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR LOWS.
THURSDAY AND THURSDAY NIGHT...SIMILAR TO THE PAST FEW DAYS...THE
PARADE OF SHORTWAVES FROM THE PACIFIC CONTINUE TO COME THROUGH THE
FAST FLOW. SHORTWAVE THAT IS NEAR/OVER THE AREA AT 12Z THURSDAY IS
PROGGED TO REACH LOWER MICHIGAN BY 00Z...WHILE ANOTHER SHORTWAVE
MOVES INTO THE DAKOTAS. SHOULD SEE THE PRECIPITATION DIMINISH FOR A
TIME THURSDAY...ESPECIALLY IN THE AFTERNOON NORTH OF I-90 AS THAT
AREA GETS INTO THE SUBSIDENCE BEHIND THE MORNING SHORTWAVE. DURING
THE AFTERNOON...PRECIPITATION IS POSSIBLE SOUTH OF I-90 AS WARM
ADVECTION OCCURS DOWNSTREAM OF THE SHORTWAVE ENTERING THE DAKOTAS.
WITH UNCERTAINTY ON THE PLACEMENT OF THE SHORTWAVE NEAR/OVER THE
AREA AT 12Z THURSDAY...ALONG WITH SUGGESTIONS OF LOW LEVEL DRY AIR
TO OVERCOME IN SOUNDINGS...HAVE KEPT PRECIPITATION CHANCES BETWEEN
20 AND 30. A LOT OF UNCERTAINTY EXISTS WITH THIS DAKOTAS SHORTWAVE
HEADING INTO THURSDAY NIGHT...WHERE THE 27.00Z ECMWF/UKMET DROP IT
DOWN INTO MISSOURI WHEREAS THE 27.00Z GFS CROSSES IOWA AND THE
27.00Z NAM CROSSES THE FORECAST AREA. FEELING IS THE SOUTHERN
SOLUTIONS MAY HAVE A BETTER CHANCE OF VERIFYING...DUE TO THE USUAL
BETTER PREDICTABILITY OF THE ECMWF...BUT NOT COMPLETELY SURE GIVEN
THE FAST FLOW. THEREFORE...20 TO 30 PERCENT CHANCES CONTINUE FOR
THURSDAY NIGHT. WITH SO MUCH UNCERTAINTY ON THE TRACKS OF THESE
SHORTWAVES...TEMPERATURE FORECASTS ARE PROBLEMATIC. CERTAINLY
POTENTIAL EXISTS ON THURSDAY FOR AT LEAST THE SOUTHERN PORTION OF
THE AREA TO HIT 40 OR HIGHER...ESPECIALLY IF THE SHORTWAVE THEN
TRACKS FARTHER NORTH. CLOUDS THURSDAY NIGHT SHOULD HOLD TEMPERATURES
UP IN THE 20S TO LOW 30S...COLDEST IN TAYLOR AND CLARK COUNTIES
WHERE COOLER AIR SINKS SOUTH BEHIND THE SHORTWAVE MOSTLY SUGGESTED
TO TRACK NEAR OR SOUTH OF THE AREA.
.LONG TERM...FRIDAY THROUGH MONDAY NIGHT
305 AM CST TUE DEC 27 2011
27.00Z MODEL CYCLE CONSISTING OF THE ECMWF/GFS/CANADIAN AND GFS
ENSEMBLES STILL PRESENT PLENTY OF UNCERTAINTY WITH REGARDS TO THE
UPPER LEVEL PATTERN THROUGHOUT THE LONG TERM PERIOD...THOUGH THERE
ARE SOME FEATURES THAT CAN BE LATCHED ONTO. THE FIRST IS A FAIRLY
POTENT SHORTWAVE TROUGH POISED TO COME INTO THE PACIFIC NORTHWEST ON
FRIDAY...RESULTING IN BUILDING RIDGING DOWNSTREAM TOWARDS THE
FORECAST AREA. THIS RIDGING LOOKS TO BUILD INTO THE AREA FRIDAY
NIGHT...BRINGING IN A SURGE OF DOWNSLOPED PACIFIC AIR. TIMING THE
PACIFIC NORTHWEST SHORTWAVE TROUGH AND INTENSITY WILL BE CRITICAL IN
DETERMINING HOW WARM NEW YEARS EVE IS. LOOKS LIKE THERE SHOULD BE
SOME WARM ADVECTION PRECIPITATION DOWNSTREAM INTO THE AREA
FRIDAY/FRIDAY NIGHT...BUT THIS MOSTLY LIFTS NORTH ON NEW YEARS EVE.
THE 26.12Z/27.00Z ECMWF RUNS ARE BY FAR THE MOST AMPLIFIED...
RESULTING IN A SLOWER COLD FRONTAL PASSAGE AND HIGH TEMPERATURES
SATURDAY FROM THE 40S INTO THE LOW 50S. FOR NOW HAVE TAKEN A 30 DAY
BIAS CORRECTION OF THE CONSENSUS OF ALL GUIDANCE...WHICH RESULTS IN
HIGHS MOSTLY IN THE 40S. CERTAINLY POTENTIAL EXISTS FOR WARMER
READINGS GIVEN LACK OF SNOW COVER STILL ANTICIPATED. COLDER AIR WILL
MOVE INTO THE AREA FOR NEW YEARS DAY AS THE UPPER TROUGH MOVES
IN...BUT HOW MUCH DEPENDS ON THE PROGRESSIVE NATURE OF THE UPPER
TROUGH. THE MORE AMPLIFIED ECMWF BASICALLY TURNS THE TROUGH INTO A
LONGWAVE TROUGH...ALLOWING FOR AIR OF MORE ARCTIC ORIGIN TO FLOW
SOUTH INTO THE AREA FOR NEW YEARS DAY AND MONDAY. ON THE OTHER
HAND...THE 27.00Z GFS/CANADIAN DEPICT MUCH MORE PROGRESSION...
RESULTING IN A CONTINUED FEED OF PACIFIC AIR AND WARMER. GIVEN SO
MUCH UNCERTAINTY...A CONSENSUS OF GUIDANCE WAS FOLLOWED FOR NEW
YEARS DAY THROUGH MONDAY NIGHT. IN EITHER MODEL CAMP SCENARIO...IT
LOOKS LIKE LITTLE IF ANY PRECIPITATION WILL OCCUR.
&&
.AVIATION...TODAY AND TONIGHT
521 AM CST TUE DEC 27 2011
GUSTY NORTHWEST WINDS AND MVFR STRATUS ARE THE MAIN CONCERNS
TODAY. A TIGHT PRESSURE GRADIENT WILL BE IN PLACE ACROSS THE AREA
TODAY AS A DEEPENING LOW PRESSURE SYSTEM MOVES INTO THE GREAT LAKES
REGION. THIS WILL RESULT IN NORTHWEST WINDS IN THE 15 TO 25KT
RANGE WITH GUSTS AROUND 30KT. LOOK FOR THE STRATUS TO SCATTER FROM
WEST TO EAST THIS AFTERNOON AS HIGH PRESSURE AND DRIER AIR MOVES
IN FROM THE PLAINS. EXPECTING VFR CONDITIONS BY 20Z AT KRST AND
AROUND 21Z AT KLSE. THE GUSTY WINDS WILL SUBSIDE AROUND SUNSET.
LOOK FOR HIGH/MID LEVEL CLOUDS TO SPREAD INTO AND THICKEN ACROSS
THE AREA THIS EVENING AND OVERNIGHT AHEAD OF A WARM FRONT MOVING
ACROSS THE NORTHERN PLAINS. OTHERWISE...VFR CONDITIONS EXPECTED TO
PREVAIL TONIGHT.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
305 AM CST TUE DEC 27 2011
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...DAS
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
554 AM EST THU DEC 29 2011
.AVIATION... / 12Z TAFS /
WARM FRONT ASSOCIATED WITH AN APPROACHING SHORTWAVE TROUGH ACROSS
THE UPPER MIDWEST WILL MIX NEWD THROUGH THE FA TODAY ALLOWING
WINDS TO VEER AND BECOME SOMEWHAT GUSTY BY LATE MORNING/AFTN. A
NARROW BROKEN BAND OF LIGHT MIXED PRECIPITATION ACROSS NRN IL AND
SRN WI MAY BRING A BRIEF PERIOD OF MAINLY LIQUID PRECIP TO THE
TERMINALS THIS MORNING. SFC TEMPS SHOULD BE BETWEEN 30 AND 32 AT
SBN WHEN THIS MOVES THROUGH SO CONTINUED WITH A 12-14Z TEMPO GROUP
FOR -FZRA HERE. THIS ACTIVITY MAY IMPACT FWA LATER THIS MORNING
WITH TEMPS LIKELY JUST ABOVE FREEZING BY THEN. KEPT VIS/CIGS VFR
WITH THE FRONTAL PASSAGE...ALTHOUGH CANNOT RULE OUT A TIME OF
MVFR CONDITIONS DURING THIS TIME...ESPECIALLY BTW 15-20Z.
OTHERWISE DRY/VFR LATER THIS AFTN AND EVENING WITH DETERIORATING
FLIGHT CONDITIONS POSSIBLE TOWARDS DAYBREAK THURSDAY AS THE NEXT
SHORTWAVE AND CHANCE FOR RAIN MOVES IN.
&&
.PREV DISCUSSION... /ISSUED 355 AM EST THU DEC 29 2011/
SHORT TERM... / TODAY THROUGH FRIDAY NIGHT /
08Z SFC ANALYSIS SHOWS A SFC LOW NEAR MSP WITH A WARM FRONT
EXTENDING SE INTO EASTERN IA AND WC IL. THE ASSOCIATED LOW
AMPLITUDE SHORTWAVE OVER THE UPPER MIDWEST WILL SHEAR OUT TOWARDS
THE CENTRAL GREAT LAKES TODAY ALLOWING THE WARM FRONT TO SURGE
NEWD INTO THE SRN GREAT LAKES. RATHER MODEST
OVERRUNNING/ISENTROPIC UPGLIDE EXPECTED JUST AHEAD OF THIS WARM
FRONT THIS MORNING INTO EARLY THIS AFTERNOON (40 KNOTS OF CROSS
ISOBARIC FLOW ON THE I290 SFC). UPSTREAM OBS/MOSAIC RADAR AND THE
BULK OF 00Z GUIDANCE SUGGEST THAT NORTHERN AREAS MAY SEE A BRIEF
PERIOD (AN HOUR OR TWO) OF VERY LIGHT PCPN THIS MORNING INTO EARLY
THIS AFTN...WITH THE BETTER CHANCES FOR MEASURABLE PCPN (A COUPLE
HUNDREDTHS AT BEST) BEING ACROSS THE NORTH/NORTHEAST WITH MAINLY
VIRGA SOUTHWEST. LATEST RUC SOUNDINGS AND SFC OBS CONTINUE TO
SUPPORT A POSSIBLE LIGHT MIX OF FREEZING DRIZZLE/SNOW TO
START...LIKELY TRANSITIONING TO A BRIEF PERIOD OF DRIZZLE. ANY
FREEZING DRIZZLE/RAIN BTW 12-15Z MAY CREATE A FEW SLICK SPOTS ON
AREA ROADS...MAINLY NORTH OF ROUTE 6. OTHERWISE...EXPECT WINDS
WILL PICK UP AND VEER BEHIND THE FRONTAL BOUNDARY WITH GUSTS OF
20-25 KNOTS POSSIBLE.
A MUCH MORE VIGOROUS SHORTWAVE NOW ACROSS THE PAC NW WILL DIG INTO
THE MID MS VALLEY AND NRN OH VALLEY BY LATER TONIGHT AND FRIDAY.
GFS/ECMWF AGREE ON 120-140 METER 500 MB HEIGHT FALLS WITH THIS
FEATURE SUPPORTING A RATHER HEALTHY LOW LVL RESPONSE AND THETA-E
ADV INTO THE AREA WITH PCPN FOCUSING ALONG A DEEPENING BAROCLINIC
ZONE. A MODEL CONSENSUS FAVORS THE NORTHERN HALF OF THE FA FOR
BEST CHANCES FOR MEASURABLE RAINFALL. AMOUNTS ARE FCST TO RANGE
BETWEEN 0.20" AND 0.50" HERE. HIRES GUIDANCE IS A LITTLE FARTHER
SOUTH WITH THE TRACK OF THIS SYSTEM SO DID CONTINUE WITH
CHC/SLIGHT WORDING FOR SNOW IN THE FAR NORTH...WITH AREAS JUST
NORTH OF THE FA IN A GOOD POSITION FOR A MODERATE SNOWFALL.
OTHERWISE...TEMPS ARE FCST TO BE ABOVE NORMAL THIS PERIOD WITH
ONLY MINOR TWEAKS MADE.
LONG TERM...
OVERALL LARGE SCALE PATTERN STILL EXPECTED TO BECOME MORE AMPLIFIED
THROUGH THE LONG TERM WITH BRIEF ARCTIC INTRUSION STILL EXPECTED
LATTER HALF OF WEEKEND INTO NEXT WEEK. MEDIUM RANGE MODELS REMAIN IN
GOOD AGREEMENT ON LARGE SCALE WITH DIFFERENCES CONTINUING IN THE
DETAILS. CR ALLBLEND LOADED AND COLLABORATED SOME TWEAKS TO TEMPS
AND POPS.
A QUIET START EXPECTED ON SATURDAY WITH WARM AIR ADVECTION AHEAD OF
FIRST COLD FRONT AND TEMPERATURES RISING WELL ABOVE NORMAL FOR LATE
DECEMBER. SHOULD SEE 40S ACROSS ENTIRE AREA FOR HIGHS WITH 50S NOT
OUT OF QUESTION SOUTH AND WEST. WARM AIR ADVECTION CONTINUES FIRST
HALF OF SATURDAY NIGHT WITH TEMPS STEADY OR SLOWLY RISING UNTIL
INITIAL FRONTAL PASSAGE LATE. HAVE TRIED TO DETAIL THIS SCENARIO IN
HOURLY GRIDS WITH STEADY TEMPS THROUGH 06Z THEN A SLOW FALL TOWARD
12Z.
DETAIL DIFFERENCES AND COMPLICATIONS IN FORECAST BEGIN IN THIS
SATURDAY NIGHT INTO SUNDAY TIME FRAME WITH STRENGTH AND TIMING OF
COLD AIR ADVECTION AND ANY ASSOCIATED PCPN. 850MB TEMPS BEGIN TO FALL
AFTER 06Z SUNDAY WITH 1000-850MB THICKNESSES FOLLOWING. MODELS
SHOWING LITTLE IN WAY OF PCPN WITH THIS FRONT GIVEN POSITIVELY
TILTED UPPER SYSTEM AND NO STRONG MOISTURE SURGE AHEAD OF IT.
DEEPENING SURFACE LOW REMAINS WELL NORTH OF AREA WITH ONLY SUBTLE
INDICATIONS OF SECONDARY LOW DEVELOPMENT ALONG FRONT BY A FEW
MODELS. HAVE THEREFORE ALLOWED LOW CHANCE POPS TO RIDE SAT NIGHT AND
SUNDAY MORNING. SUNDAY BEGINNING TO LOOK DRY IN WAKE OF INITIAL COLD
FRONT WITH SOME SUNSHINE EVEN POSSIBLE IN DRY SLOT BEFORE SECONDARY
ARCTIC FRONT LATER IN THE DAY. IF THIS OCCURS...FALLING TEMPS EARLY
IN THE MORNING MAY BECOME STEADY OR EVEN RISE A FEW DEGREES BEFORE
SECONDARY FRONT BRINGS MUCH COLDER AIR IN DURING THE AFTERNOON.
FOR NOW HAVE CHOSEN TO GO WITH SLOWLY FALLING TEMPS DURING THE DAY
GIVEN TEMPS LOOK TO FALL IN THE AFTERNOON REGARDLESS.
WITH ARCTIC INTRUSION SUNDAY NIGHT WILL SEE BEST LAKE EFFECT SNOW
POTENTIAL OF THE SEASON AS DELTA T VALUES CLIMB WITH SURFACE TO
850MB WELL INTO LOWER 20S. SURFACE TO 700MB DELTA T VALUES REACH
CRITICAL 30C THRESHOLD WHICH IS A GOOD INDICATOR OF HEAVY SNOW
POTENTIAL. LIMITING FACTOR CONTINUES TO BE MOISTURE PROFILES BUT
MEDIUM RANGE MODELS ARE SHOWING SOME DECENT SYNOPTIC MOISTURE LATE
SUNDAY NIGHT THROUGH MONDAY WHICH WOULD SUPPORT A PERIOD OF HEAVY
LAKE EFFECT SNOW BANDS. NORTHWEST FLOW AND WIND FIELD SUGGEST
MULTI-BANDED EVENT WHICH MAKES PINNING DOWN AMOUNTS AND LOCATIONS
DIFFICULT AT THIS TIME PROJECTION. HAVE BUMPED NW FETCH FAVORED
AREAS INTO LIKELY CATEGORY FOR NOW. HEADLINES POSSIBLE LATER THIS
WEEKEND INTO EARLY NEXT WEEK AS MOISTURE PROFILES BECOME BETTER
DEFINED BY HIGHER RESOLUTION MODELS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EST THIS EVENING FOR LMZ043.
SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR LMZ046.
&&
$$
SHORT TERM...STEINWEDEL
LONG TERM...LASHLEY
AVIATION...STEINWEDEL
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
858 AM CST THU DEC 29 2011
.AVIATION...
CURRENTLY VFR CEILINGS ACROSS THE MID MISSISSIPPI VALLEY THIS
MORNING WITH MVFR TO IFR CEILINGS ACROSS CENTRAL MINNESOTA.
UPDATED THE PREVIOUS SET OF TAFS TO REMOVE MVFR CEILINS AT KDBQ AS
AS THE LOWER CEILINGS ARE EXPECTED TO REMAIN TO THE NORTH AND EAST
OF THESE TAF SITES.
DC/JH
&&
.PREV DISCUSSION... /ISSUED 652 AM CST THU DEC 29 2011/
UPDATE...
A FEW SHRA/S HAVE DEVELOPED FROM NEAR QUAD CITIES S/E WITHIN AREA
OF MID LEVEL INSTABILITY AHEAD OF VORT MAX. UPDATED TO ADD ISOLD
MENTION AND SHOULD BE OUT OF CWA NEXT 1-2 HRS. NEXT CONCERN IS
CLOUD TRENDS. LEADING EDGE OF STRATUS HAS DISSIPATED OVER SOUTHERN
MN AND NOTICING PAST FEW HRS OF CIG TRENDS FROM RUC BACKUP MODEL
KEEPS LOW CLOUDS TO N/W OF CWA TDY. THIS LOOKS REASONABLE GIVEN
RECENT TRENDS PLUS THE ADDITIONAL RAPID EROSION TO STRATUS OVER ND
DUE TO WARM ADVECTION ALOFT. WILL BE UPDATING TO BE MORE OPTIMISTIC
WITH SKY COVER NORTH HALF AND TWEAK MAXES UP A COUPLE DEGS.
PREV DISCUSSION... /ISSUED 411 AM CST THU DEC 29 2011/
SYNOPSIS...
STARTING OUT THIS AM WITH TEMPS THAT ALREADY AT OR 5+ DEGS ABOVE NORMAL
HIGHS. ALWAYS A GREAT SIGN AND HARBINGER OF WHAT IS TO COME TDY.
QUASI-ZONAL FLOW FULL OF ENERGY EARLY THIS AM. WATER VAPOR IMAGERY AND
PROFILERS DEPICT SHORTWAVE NEAR PICKLE LAKE ONTARIO (CYPL) WITH
SECONDARY WAVE FURTHER SOUTH NEAR LACROSSE WI... BOTH SLIDING E/SE.
ATTENDANT SFC LOW WAS LOCATED CLOSE TO SAINT CLOUD MN WITH COLD FRONT
EXTENDING WNWD INTO NORTHERN SD WHILE WARM FRONT WAS DRAPED SEWD INTO
EASTERN IA. WARM ADVECTION WING WITH JUST TRACE AMOUNTS OF PCPN PASSING
QUICKLY THROUGH NORTHERN IL. MOST OBS THIS FAR SOUTH HAVE BEEN REPORTING
SPRINKLES BUT A COUPLE OF QUESTION MARKS SHOWING ON SOME ASOS NEAR WI/IL
BORDER INTO SOUTHERN WI AND SO CANT RULE OUT SOME FLAKES OR EVEN ICE
PELLETS BUT NO GROUND TRUTH REPORTS. THIS WILL BE EXITING SHORTLY WITH
SKIES CLEARING INTO EASTERN IA IN WAKE OF WARM ADVECTION. SATL SHOWS
A LARGE AREA OF LOW CLOUDS OVER ND... FAR NORTHEAST SD AND WESTERN MN ON
BACKSIDE OF SFC LOW IN LOW LEVEL COLD ADVECTION WHICH HAVE BEEN SLIDING
SEWD. MEANWHILE... NEXT BARRAGE OF ENERGY IN VERY ENERGETIC PACIFIC WAVE
TRAIN PLOWING THROUGH PACIFIC NW AND NORTHERN ROCKIES... AND ITS THIS
ENERGY THAT WILL AID IN BRINGING PCPN TO PORTIONS OF THE REGION TNGT-FRI.
SHORT TERM...TODAY AND TONIGHT...
EYES ARE POINTED NW EARLY THIS AM. SFC LOW OVER CENTRAL MN TO DIVE E/SE
THROUGH SOUTHERN WI TDY WITH TRAILING COLD FRONT SWEEPING ACROSS THE
CWA. THUS... WARM ADVECTION ON GUSTY SW WINDS TO START OFF WILL
EVENTUALLY BE REPLACED WITH COLD ADVECTION ON GUSTY W/NW WINDS. BEST
COLD ADVECTION PROGGED NORTH THIRD TO HALF OF CWA WHERE ALSO EXPECT TO SEE
SOME STRATUS TURNING SKIES FROM SUNNY TO PT-MOCLDY. TEMPS EVERYWHERE WELL
ABOVE NORMAL BY CLOSE TO 15+ DEGS... WITH COOLEST READINGS NORTH WHERE WENT
WITH AROUND 40/L40S DUE TO ANTICIPATION OF LOW CLOUDS BY MID-LATE AM. FROM
THERE ON SOUTH TEMPS WARMING WELL INTO THE 40S WITH 50S OVER SE IA... WCNTRL
IL AND NE MO.
TNGT... ANOTHER DOUBLE BARREL ENERGY COMPLEX EXPECTED TO SHIFT FROM THE
PLAINS INTO UPPER MIDWEST. ROBUST WARM ADVECTION TO GENERATE PCPN THAT WILL
MOVE ACROSS MUCH OF AREA BY MID-LATE EVE AND OVRNGT ESPECIALLY NORTH
OF KOTM-KBRL LINE. FCST SOUNDINGS AND LATEST SUITE OF SREF PTYPE PROBS ALL
SUPPORT PCPN WILL BE RAIN. UKMET AND ECMWF STRONGER WITH ENERGY RESULTING IN
DEEPER SFC LOW FOR EVEN WARMER DRAW AGAIN SUPPORTING RAIN AS THEY SHOW H85
LOW MOVING INTO NE IA 12Z FRI... PLACING BETTER SNOW CHCS NORTH OR LEFT OF THE
H85 LOW TRACK. QPF AMOUNTS WILL BE LIGHT AND GENERALLY A TENTH OR TWO AT MOST.
TEMPS WILL DROP OFF A BIT EARLY THIS EVE THEN BECOME STEADY AND SLOWLY RISE
WITH ONSET OF LOW LEVEL WARM ADVECTION. ..05..
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
FRIDAY...STILL SOME VARIANCE BETWEEN THE 00Z MODEL RUNS INTO FRI
WITH HANDLING AND DEVELOPMENT OF THE PASSING WAVE COMPLEX. BUT
WITH THE PROGRESSIVE NATURE OF THE CURRENT REGIME PATTERN WE HAVE
BEEN IN THIS WEEK AND LOOKING AT UPPER JET DYNAMICS THROUGH FRI
NIGHT... FEEL THE 00Z RUN GFS SOLUTION THE ONE TO FOLLOW FOR NOW
THIS PERIOD. ALSO PREFER THE FURTHER NORTH LOW TO MID LEVEL WAVE
PROGRESSION ACRS THE REGION IN LINGERING POSITIVE AO. THIS
ACCEPTED GFS SOLUTION SUGGESTS BULK OF ANY PRECIP SHIELD
ASSOCIATED WITH THE PASSING LOW WILL BE ON THE MOVE OUT OF THE DVN
CWA FRI MORNING AFTER 12Z. WILL WALK OUT PRECIP IN THE MORE WITH
LIKELY POPS IN THE FAR NORTHEAST... AND LESSER CHC POPS FURTHER TO
THE WEST AND SOUTH. IT ALSO APPEARS IN-WRAPPING LLVL COLD CONVEYOR
OR TOP-DOWN COOLING ENOUGH FOR A CHANGE OVER TO SNOW WILL OCCUR
AFTER THE BULK OF ANY MEASURING PRECIP EXITS THE AREA AS WELL. BUT
PROJECTED THERMAL PROFILES ARE CLOSE THROUGH 15Z FRI ALONG AND
NORTH OF THE HWY 20 CORRIDOR AND WILL MENTION A MIX IN THOSE AREAS
BUT WITH LITTLE IF ANY SNOW ACCUM. LOW TO MID LEVEL DRYING/RH
DECREASE LATE MORNING THOUGH MIDDAY AS LOW CENTER PASSES...THEN
SYSTEM WRAP AROUND STRATOCU ENGULFS MUCH OF THE CWA FRI AFTERNOON
INTO THE EVENING. EXTENT OF PRECIP POTENTIAL IN THIS WRAP AROUND
DECK UNCERTAIN ALONG WITH ADEQUATE MOISTURE DEPTH FOR MEASURABLE.
FOR NOW WILL JUST GO WITH A SLIGHT CHC OF LIGHT RAIN OR LIGHT SNOW
IN THE FAR NORTH FRI AFTERNOON...BUT IT MAY BE NOT MUCH MORE THAN
FLURRIES OR SPRINKLES. FRI HIGHS RANGING FROM AROUND 40 IN THE FAR
NORTH..TO NEAR 50 IN THE FAR SOUTH. THEN EXPECT THE CLOUDS TO
CLEAR TO THE EAST FRI NIGHT WITH SFC WIND DROP OFF WITH PASSING
SFC RIDGE LOBE. LOWS IN THE UPPER 20S TO LOWER 30S FOR NOW BUT IT
MAY BE COOLER DEPENDING ON IF RETURN FLOW CAN COMMENCE TOWARD SAT
MORNING IN TIME TO HALT THE TEMP DROP-OFF ESPECIALLY WEST OF THE
MS RVR.
SATURDAY AND SUNDAY...LOOKING AT THE LATEST 00Z RUN MEDIUM RANGE
MODELS AND WARM UP POTENTIAL AHEAD OF A SUBSTANTIAL IMPULSE TRYING TO
PHASE OVER THE MID CONUS ON SAT...DURATION OF THE WARM TONGUE
AND MIXING DEPTH STILL AT QUESTION ENOUGH TO FUEL THE ADVERTISED DAY
WELL IN THE 50S. WILL MAKE ONLY MINOR ADJUSTMENTS TO SAT HIGHS FOR
NOW AS STILL SOMEWHAT HESITANT TO GO CRAZY WITH THE FULL WARM UP
POTENTIAL. BUT EVEN WITH THE CURRENT PROJECTED THERMAL PROFILES AND
FCST SOUNDINGS...JUST MIXING UP TO AROUND H9 MB/INTO BASE OF A VERY
PRONOUNCED WARM WEDGE ALOFT/INVERSION CENTERED AROUND H85 MB...HIGHS
WOULD BE IN THE MID 50S WITH A FEW LOCATIONS PUSHING THE UPPER 50S IN
THE SOUTHWESTERN CWA. THE MODELS THEN REALLY START TO DIVERGE NEW
YEARS EVE/SAT NIGHT WITH RESPECT TO CONTINUED DEVELOP OF A L/W TROF
AND ASSOCIATED DEEPENING LLVL CYCLONE OVER THE UPPER MIDWEST AND
NORTHWESTERN GRT LKS. BUT THE GENERAL ENSEMBLES SUGGEST THAT THE
DVN CWA WILL REMAIN DRY SAT NIGHT AND MILD THROUGH MIDNIGHT/HELD UP
WELL IN THE 40S BEFORE IN-SWIRLING COLD PUSH MAKES IT ACRS THE AREA
FROM NW-TO-SE AFTER 09Z SUNDAY. STILL SOME DETAILS TO REFINE WITH
THIS PERIOD OVER THE NEXT 24-36 HRS OF MODEL RUNS. AS FOR NEW YEARS
DAY SUNDAY...A WINDY RAW DAY WITH MORNING HIGHS AND THEN FALLING
TEMPS AS NORTHWEST SFC WINDS GUST OVER 30 MPH IN ROBUST CAA REGIME
UNDER AMPLIFYING PATTERN. THE ECMWF STILL THE MOST DEVELOPED WITH
HIGH AMPLITUDE NEAR MERIDIONAL FETCH DEVELOPING ACRS THE WESTERN GRT
LKS BY MONDAY MORNING. H85 TEMPS BY 12Z MON IN NEGATIVE MID TEENS C
AND LOWS SUNDAY NIGHT PROBABLY WELL DOWN IN THE TEENS DESPITE
ONGOING MIXING WINDS OF 15-25 MPH EVEN AT NIGHT. WILL KEEP SUNDAY
DRY BUT IN SUCH A REGIME WOULD EXPECT COL AIR STRATUS TO BLANKET THE
AREA ALONG WITH SOME EMBEDDED FLURRIES.
MONDAY THROUGH WEDNESDAY...WILL KEEP HIGH AMPLITUDE ARCTIC AIRMASS
DUMP INTO THE MIDWEST GOING MON AND MON NIGHT. MONDAY HIGHS
PROBABLY NOT TO GET OUT OF THE LOW TO MID 20S WITH ONGOING GUSTY
NORTHWEST WINDS OF 20-30 MPH AND HIGHER GUSTS. SFC RIDGE LOBE
SLIDING ACRS THE CWA...SFC WIND DECOUPLE AND STRATUS CLEAR OFF COULD
FOSTER SINGLE DIGIT LOWS OVER SOME PORTIONS OF THE DVN CWA BY TUE
MORNING EVEN OVER SNOWCOVER-LESS TERRAIN. AGAIN WILL GO DRY IN THE
GRIDS ON MONDAY BUT WOULD BET SOME CAA FLURRIES CONTINUING TO GET
MILKED OUT OF WHATEVER MOISTURE THERE IS ACRS THE AREA. LONGER RANGE
SIGNALS SUGGEST THE FLOW WILL TRY TO FLATTEN OUT AGAIN TOWARD MID
NEXT WEEK AS ARCTIC OSCILLATION/AO PROGS MIGRATE BACK TOWARD THE
POSITIVE. BUT THERMAL MODERATION INTO TUE TO BE SLOW AND MORE
REALIZED BY NEXT WED WITH HIGHS RETURNING TO THE MID AND UPPER 30S.
THIS PROCESS MAY BE AIDED BY A WARM DRAW TO THE SOUTH OF CLIPPER TYPE
SYSTEM DROPPING FROM SASKATCHEWAN TO WI SOMETIME DURING THIS TUE INTO
WED PERIOD. ..12..
AVIATION... /ISSUED 1137 PM CST WED DEC 28 2011/
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
652 AM CST THU DEC 29 2011
.UPDATE...
A FEW SHRA/S HAVE DEVELOPED FROM NEAR QUAD CITIES S/E WITHIN AREA
OF MID LEVEL INSTABILTY AHEAD OF VORT MAX. UPDATED TO ADD ISOLD
MENTION AND SHOULD BE OUT OF CWA NEXT 1-2 HRS. NEXT CONCERN IS
CLOUD TRENDS. LEADING EDGE OF STRATUS HAS DISSIPATED OVER SOUTHERN
MN AND NOTICING PAST FEW HRS OF CIG TRENDS FROM RUC BACKUP MODEL
KEEPS LOW CLOUDS TO N/W OF CWA TDY. THIS LOOKS REASONABLE GIVEN
RECENT TRENDS PLUS THE ADDITIONAL RAPID EROSION TO STRATUS OVER ND
DUE TO WARM ADVECTION ALOFT. WILL BE UPDATING TO BE MORE OPTIMISTIC
WITH SKY COVER NORTH HALF AND TWEAK MAXES UP A COUPLE DEGS.
&&
.AVIATION... /ISSUED 558 AM CST THU DEC 29 2011/
CURRENTLY..WEAK RETURNS ARE SHOWING UP ON RADAR IN THE VICINITY OF
KBRL AND KMLI AND MAY AFFECT THESE TERMINALS THROUGH 13 UTC. MVFR
CEILINGS IN THE WAKE OF THIS MORINGS CLIPPER SYSTEM WILL BRUSH
KDBQ BETWEEN 15 AND 18 UTC WITH SCT CEILINGS AT KCID. AFTER 18 UTC
ALL TAF SITES WILL BE VFR THROUGH 03 UTC WHEN A MUCH STRONGER
CLIPPER SYSTEM APPROACHES THE MID MISSISSIPPI VALLEY. MVFR
CEILINGS MOVE INTO KCID AND KDBQ BY 06 UTC WITH PERIODS OF RAIN
THROUGH THE END OF THE PERIOD. RAIN WILL NOT BE AS WIDESPREAD AT
KBRL AND KMLI AND MAY ONLY OCCURR FOR A BRIEF PERIOD SO USED VCSH
AS TIMING IS UNCERTAIN AND LEFT CEILINGS AT VFR WITH BETTER LOW
LEVEL MOISTURE TO THE NORTH AND EAST.
..DC/MM..
&&
.PREV DISCUSSION... /ISSUED 411 AM CST THU DEC 29 2011/
SYNOPSIS...
STARTING OUT THIS AM WITH TEMPS THAT ALREADY AT OR 5+ DEGS ABOVE NORMAL
HIGHS. ALWAYS A GREAT SIGN AND HARBINGER OF WHAT IS TO COME TDY.
QUASI-ZONAL FLOW FULL OF ENERGY EARLY THIS AM. WATER VAPOR IMAGERY AND
PROFILERS DEPICT SHORTWAVE NEAR PICKLE LAKE ONTARIO (CYPL) WITH
SECONDARY WAVE FURTHER SOUTH NEAR LACROSSE WI... BOTH SLIDING E/SE.
ATTENDANT SFC LOW WAS LOCATED CLOSE TO SAINT CLOUD MN WITH COLD FRONT
EXTENDING WNWD INTO NORTHERN SD WHILE WARM FRONT WAS DRAPED SEWD INTO
EASTERN IA. WARM ADVECTION WING WITH JUST TRACE AMOUNTS OF PCPN PASSING
QUICKLY THROUGH NORTHERN IL. MOST OBS THIS FAR SOUTH HAVE BEEN REPORTING
SPRINKLES BUT A COUPLE OF QUESTION MARKS SHOWING ON SOME ASOS NEAR WI/IL
BORDER INTO SOUTHERN WI AND SO CANT RULE OUT SOME FLAKES OR EVEN ICE
PELLETS BUT NO GROUND TRUTH REPORTS. THIS WILL BE EXITING SHORTLY WITH
SKIES CLEARING INTO EASTERN IA IN WAKE OF WARM ADVECTION. SATL SHOWS
A LARGE AREA OF LOW CLOUDS OVER ND... FAR NORTHEAST SD AND WESTERN MN ON
BACKSIDE OF SFC LOW IN LOW LEVEL COLD ADVECTION WHICH HAVE BEEN SLIDING
SEWD. MEANWHILE... NEXT BARRAGE OF ENERGY IN VERY ENERGETIC PACIFIC WAVE
TRAIN PLOWING THROUGH PACIFIC NW AND NORTHERN ROCKIES... AND ITS THIS
ENERGY THAT WILL AID IN BRINGING PCPN TO PORTIONS OF THE REGION TNGT-FRI.
SHORT TERM...TODAY AND TONIGHT...
EYES ARE POINTED NW EARLY THIS AM. SFC LOW OVER CENTRAL MN TO DIVE E/SE
THROUGH SOUTHERN WI TDY WITH TRAILING COLD FRONT SWEEPING ACROSS THE
CWA. THUS... WARM ADVECTION ON GUSTY SW WINDS TO START OFF WILL
EVENTUALLY BE REPLACED WITH COLD ADVECTION ON GUSTY W/NW WINDS. BEST
COLD ADVECTION PROGGED NORTH THIRD TO HALF OF CWA WHERE ALSO EXPECT TO SEE
SOME STRATUS TURNING SKIES FROM SUNNY TO PT-MOCLDY. TEMPS EVERYWHERE WELL
ABOVE NORMAL BY CLOSE TO 15+ DEGS... WITH COOLEST READINGS NORTH WHERE WENT
WITH AROUND 40/L40S DUE TO ANTICIPATION OF LOW CLOUDS BY MID-LATE AM. FROM
THERE ON SOUTH TEMPS WARMING WELL INTO THE 40S WITH 50S OVER SE IA... WCNTRL
IL AND NE MO.
TNGT... ANOTHER DOUBLE BARREL ENERGY COMPLEX EXPECTED TO SHIFT FROM THE
PLAINS INTO UPPER MIDWEST. ROBUST WARM ADVECTION TO GENERATE PCPN THAT WILL
MOVE ACROSS MUCH OF AREA BY MID-LATE EVE AND OVRNGT ESPECIALLY NORTH
OF KOTM-KBRL LINE. FCST SOUNDINGS AND LATEST SUITE OF SREF PTYPE PROBS ALL
SUPPORT PCPN WILL BE RAIN. UKMET AND ECMWF STRONGER WITH ENERGY RESULTING IN
DEEPER SFC LOW FOR EVEN WARMER DRAW AGAIN SUPPORTING RAIN AS THEY SHOW H85
LOW MOVING INTO NE IA 12Z FRI... PLACING BETTER SNOW CHCS NORTH OR LEFT OF THE
H85 LOW TRACK. QPF AMOUNTS WILL BE LIGHT AND GENERALLY A TENTH OR TWO AT MOST.
TEMPS WILL DROP OFF A BIT EARLY THIS EVE THEN BECOME STEADY AND SLOWLY RISE
WITH ONSET OF LOW LEVEL WARM ADVECTION. ..05..
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
FRIDAY...STILL SOME VARIANCE BETWEEN THE 00Z MODEL RUNS INTO FRI
WITH HANDLING AND DEVELOPMENT OF THE PASSING WAVE COMPLEX. BUT
WITH THE PROGRESSIVE NATURE OF THE CURRENT REGIME PATTERN WE HAVE
BEEN IN THIS WEEK AND LOOKING AT UPPER JET DYNAMICS THROUGH FRI
NIGHT... FEEL THE 00Z RUN GFS SOLUTION THE ONE TO FOLLOW FOR NOW
THIS PERIOD. ALSO PREFER THE FURTHER NORTH LOW TO MID LEVEL WAVE
PROGRESSION ACRS THE REGION IN LINGERING POSITIVE AO. THIS
ACCEPTED GFS SOLUTION SUGGESTS BULK OF ANY PRECIP SHIELD
ASSOCIATED WITH THE PASSING LOW WILL BE ON THE MOVE OUT OF THE DVN
CWA FRI MORNING AFTER 12Z. WILL WALK OUT PRECIP IN THE MORE WITH
LIKELY POPS IN THE FAR NORTHEAST... AND LESSER CHC POPS FURTHER TO
THE WEST AND SOUTH. IT ALSO APPEARS IN-WRAPPING LLVL COLD CONVEYOR
OR TOP-DOWN COOLING ENOUGH FOR A CHANGE OVER TO SNOW WILL OCCUR
AFTER THE BULK OF ANY MEASURING PRECIP EXITS THE AREA AS WELL. BUT
PROJECTED THERMAL PROFILES ARE CLOSE THROUGH 15Z FRI ALONG AND
NORTH OF THE HWY 20 CORRIDOR AND WILL MENTION A MIX IN THOSE AREAS
BUT WITH LITTLE IF ANY SNOW ACCUM. LOW TO MID LEVEL DRYING/RH
DECREASE LATE MORNING THOUGH MIDDAY AS LOW CENTER PASSES...THEN
SYSTEM WRAP AROUND STRATOCU ENGULFS MUCH OF THE CWA FRI AFTERNOON
INTO THE EVENING. EXTENT OF PRECIP POTENTIAL IN THIS WRAP AROUND
DECK UNCERTAIN ALONG WITH ADEQUATE MOISTURE DEPTH FOR MEASURABLE.
FOR NOW WILL JUST GO WITH A SLIGHT CHC OF LIGHT RAIN OR LIGHT SNOW
IN THE FAR NORTH FRI AFTERNOON...BUT IT MAY BE NOT MUCH MORE THAN
FLURRIES OR SPRINKLES. FRI HIGHS RANGING FROM AROUND 40 IN THE FAR
NORTH..TO NEAR 50 IN THE FAR SOUTH. THEN EXPECT THE CLOUDS TO
CLEAR TO THE EAST FRI NIGHT WITH SFC WIND DROP OFF WITH PASSING
SFC RIDGE LOBE. LOWS IN THE UPPER 20S TO LOWER 30S FOR NOW BUT IT
MAY BE COOLER DEPENDING ON IF RETURN FLOW CAN COMMENCE TOWARD SAT
MORNING IN TIME TO HALT THE TEMP DROP-OFF ESPECIALLY WEST OF THE
MS RVR.
SATURDAY AND SUNDAY...LOOKING AT THE LATEST 00Z RUN MEDIUM RANGE
MODELS AND WARM UP POTENTIAL AHEAD OF A SUBSTANTIAL IMPULSE TRYING TO
PHASE OVER THE MID CONUS ON SAT...DURATION OF THE WARM TONGUE
AND MIXING DEPTH STILL AT QUESTION ENOUGH TO FUEL THE ADVERTISED DAY
WELL IN THE 50S. WILL MAKE ONLY MINOR ADJUSTMENTS TO SAT HIGHS FOR
NOW AS STILL SOMEWHAT HESITANT TO GO CRAZY WITH THE FULL WARM UP
POTENTIAL. BUT EVEN WITH THE CURRENT PROJECTED THERMAL PROFILES AND
FCST SOUNDINGS...JUST MIXING UP TO AROUND H9 MB/INTO BASE OF A VERY
PRONOUNCED WARM WEDGE ALOFT/INVERSION CENTERED AROUND H85 MB...HIGHS
WOULD BE IN THE MID 50S WITH A FEW LOCATIONS PUSHING THE UPPER 50S IN
THE SOUTHWESTERN CWA. THE MODELS THEN REALLY START TO DIVERGE NEW
YEARS EVE/SAT NIGHT WITH RESPECT TO CONTINUED DEVELOP OF A L/W TROF
AND ASSOCIATED DEEPENING LLVL CYCLONE OVER THE UPPER MIDWEST AND
NORTHWESTERN GRT LKS. BUT THE GENERAL ENSEMBLES SUGGEST THAT THE
DVN CWA WILL REMAIN DRY SAT NIGHT AND MILD THROUGH MIDNIGHT/HELD UP
WELL IN THE 40S BEFORE IN-SWIRLING COLD PUSH MAKES IT ACRS THE AREA
FROM NW-TO-SE AFTER 09Z SUNDAY. STILL SOME DETAILS TO REFINE WITH
THIS PERIOD OVER THE NEXT 24-36 HRS OF MODEL RUNS. AS FOR NEW YEARS
DAY SUNDAY...A WINDY RAW DAY WITH MORNING HIGHS AND THEN FALLING
TEMPS AS NORTHWEST SFC WINDS GUST OVER 30 MPH IN ROBUST CAA REGIME
UNDER AMPLIFYING PATTERN. THE ECMWF STILL THE MOST DEVELOPED WITH
HIGH AMPLITUDE NEAR MERIDIONAL FETCH DEVELOPING ACRS THE WESTERN GRT
LKS BY MONDAY MORNING. H85 TEMPS BY 12Z MON IN NEGATIVE MID TEENS C
AND LOWS SUNDAY NIGHT PROBABLY WELL DOWN IN THE TEENS DESPITE
ONGOING MIXING WINDS OF 15-25 MPH EVEN AT NIGHT. WILL KEEP SUNDAY
DRY BUT IN SUCH A REGIME WOULD EXPECT COL AIR STRATUS TO BLANKET THE
AREA ALONG WITH SOME EMBEDDED FLURRIES.
MONDAY THROUGH WEDNESDAY...WILL KEEP HIGH AMPLITUDE ARCTIC AIRMASS
DUMP INTO THE MIDWEST GOING MON AND MON NIGHT. MONDAY HIGHS
PROBABLY NOT TO GET OUT OF THE LOW TO MID 20S WITH ONGOING GUSTY
NORTHWEST WINDS OF 20-30 MPH AND HIGHER GUSTS. SFC RIDGE LOBE
SLIDING ACRS THE CWA...SFC WIND DECOUPLE AND STRATUS CLEAR OFF COULD
FOSTER SINGLE DIGIT LOWS OVER SOME PORTIONS OF THE DVN CWA BY TUE
MORNING EVEN OVER SNOWCOVER-LESS TERRAIN. AGAIN WILL GO DRY IN THE
GRIDS ON MONDAY BUT WOULD BET SOME CAA FLURRIES CONTINUING TO GET
MILKED OUT OF WHATEVER MOISTURE THERE IS ACRS THE AREA. LONGER RANGE
SIGNALS SUGGEST THE FLOW WILL TRY TO FLATTEN OUT AGAIN TOWARD MID
NEXT WEEK AS ARCTIC OSCILLATION/AO PROGS MIGRATE BACK TOWARD THE
POSITIVE. BUT THERMAL MODERATION INTO TUE TO BE SLOW AND MORE
REALIZED BY NEXT WED WITH HIGHS RETURNING TO THE MID AND UPPER 30S.
THIS PROCESS MAY BE AIDED BY A WARM DRAW TO THE SOUTH OF CLIPPER TYPE
SYSTEM DROPPING FROM SASKATCHEWAN TO WI SOMETIME DURING THIS TUE INTO
WED PERIOD. ..12..
AVIATION... /ISSUED 1137 PM CST WED DEC 28 2011/
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1043 AM EST THU DEC 29 2011
...Forecast Update...
Just some minor updates made to the grids late this morning. AC
continues to move overhead, and will gradually move out of the
region this afternoon. With the morning clouds giving a slow start
to temperature rises, have dropped MaxT just a couple of degrees in
the northeast where temperatures are coolest and clouds are most
common and will be the most long-lived.
BUFKIT has backed off on its wind gust forecasts for this afternoon,
but the HRRR keeps us quite gusty and with the sun returning for the
afternoon hours, will just knock the wind gust forecast down a
couple knots. Gusts to 25 mph still look attainable...maybe even
still to 30 mph over southern Indiana and northern Kentucky.
Tweaked clouds in the far south and southwest where skies are
clearer than farther north.
&&
.Short Term (Today and Tonight)...
A couple of low pressure systems will swiftly move across the Great
Lakes region throughout the short-term, with the first occurring
today, and the second fast on its heels late tonight. These two
systems will not only bring increased mid-upper cloudiness to our
region today and tonight, but will also increase our winds quite a
bit out of the southwest. Because of this, temperatures will
moderate some and will likely be at or just over the warmest MOS
guidance.
After a chilly start to today, expect highs under filtered sunshine
to climb into the low-mid 50s, with lows tonight only dropping down
to around 40 or the low 40s. With good mixing, expect 15mph
sustained winds out of the southwest, with gusts as high as 25-30 at
times from late morning through the afternoon hours.
The second system approaching late tonight from the northwest will
bring light rain to central IL/IN after midnight tonight. This
activity should stay north of our CWA through 12z Friday so kept the
latter portion of tonight`s forecast dry.
.Long Term (Friday - Wednesday)...
The models have come into much better agreement with the weather
systems for the long term versus this time last night. There will be
a couple of chances for precipitation through this period, though
neither looks to bring widespread precip to the area.
The first system will be Friday as a shortwave tracks across
the upper Midwest and into the Great Lakes region. Southern Indiana
and north central Kentucky will stand the best chance of seeing any
light rain from this system as it quickly tracks eastward Friday.
The rain will quickly move off to the east Friday evening, with
Saturday remaining dry. For Friday winds will be fairly breezy out
of the southwest. Temperatures Friday through Saturday will remain
well above normal with highs in the mid 50s and lows in the upper
30s to lower 40s.
For Sunday, a strong low pressure system will move out of WI/MN and
into southern Canada. This will swing a strong cold front through on
Sunday. Most of the moisture associated with this system looks to be
closer to the low, so will continue to mention only slight chance to
low chance pops. Additionally, models continue to speed up the exit
of the precipitation. Think most precip will be out of the area
before the cold air has a chance to overspread the region, so have
taken out the mention of the rain/snow mix on Sunday night.
Much colder air will settle into the Ohio Valley in the wake of this
system. Highs on Monday will be only in the low to middle 30s while
Tuesday`s highs may not make it out of the 20s in some locations.
Lows will be in the lower 20s to teens. Wednesday looks to start a
gradual warm up into the latter half of the week.
&&
.Aviation (12Z TAF Issuance)...
A couple of disturbances will cross the northern U.S. through this
TAF period. Mid level clouds associated with the first system are
already streaming across the region. Skies may clear for a bit this
evening before more clouds move in overnight. The only concern today
will be gusty winds this afternoon. Winds will increase out of the
southwest after 15-16Z. Winds will be sustained at 12-15 knots with
gusts to 22-25 knots. Gusts will decrease this evening, but winds
will remain around 10 knots out of the southwest overnight. The
second system crossing the area tomorrow may bring some light rain
to SDF. However, with certainty low and little impact expected from
the rain, will keep it out of the TAF for now.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...NONE.
$$
Update...........13
Short Term.......AL
Long Term........EER
Aviation.........AL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
631 AM EST THU DEC 29 2011
UPDATED AVIATION DISCUSSION FOR 12Z TAFS
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG WRLY MID/UPPER LEVEL
FLOW INTO THE PAC NW AND WNW FLOW DOWNSTREAM FROM THE SRN CANADA AND
NRN PLAINS INTO THE GREAT LAKES. ONE SHEARED SHORTWAVE TROUGH WAS
LOCATED NORTH OF LAKE SUPERIOR AND ANOTHER WAS MOVING THROUGH SW MN.
AT THE SFC...A 997 MB LOW WAS LOCATED OVER SRN MN RESULTING IN S TO
SE WINDS ACROSS UPPER MICHIGAN. AN AREA OF SNOW FROM NE MN INTO WRN
LAKE SUPERIOR NW WI WITH VSBYS INTO THE 1-3SM RANGE WAS SUPPORTED BY
285K-290K ASCENT AHEAD OF A 850-700 MB TROUGH. ANY LAKE EFFECT/ENHANCED
SNOW OFF OF LAKE MICHIGAN WITH THE SRLY FLOW HAS BEEN MINIMAL WITH
ONLY A DUSTING AT MOST.
&&
.DISCUSSION...
TODAY AND TONIGHT...EXPECT THE AREA OF SNOW TO PROGRESS ACROSS UPPER
MICHIGAN TODAY. MODELS CONSENSUS QPF OF AROUND A TENTH OF AN INCH
WITH SNOW/WATER RATIO VALUES NEAR 15/1 WOULD RESULT IN SNOWFALL
AMOUNTS OF AN INCH OR TWO WHICH IS REASONABLE GIVEN 2G-3G/KG
MOISTURE AVBL NEAR 700MB DURING A 6 HOUR PERIOD OF STRONGER LIFT.
UNCERTAINTY REMAINS WITH REGARD TO LAKE ENHANCED SNOW POTENTIAL INTO
THE SE CWA. THE HIGHER RES MODELS HAVE BEEN OVERDOING PCPN WITH
BANDS OFF OF LAKE MICHIGAN SO FAR. HOWEVER...AS THE DEEPER MOISTURE
ARRIVES...EXPECT THAT THE LAKE CONTRIBUTION MAY ADD AN ADDITIONAL
1-2 INCHES TO SNOWFALL AMOUNTS. SINCE THE WINDS WERE BACKING MORE
SERLY AHEAD OF THE LOW...THE BEST LOW LEVEL CONV AND OVER WATER
TRAJECTORIES HAVE SHIFTED TO THE WEST. SO...HAVE CANCELLED THE ADVY
FOR LUCE COUNTY AND CONTINUED MENTION OF 2 TO 4 INCHES OF SNOW IN
THE ADVY FOR SCHOOLCRAFT COUNTY TODAY. MODELS SUGGEST THAT THE
DEEPER MOISTURE WILL QUICKLY DEPART THIS AFTERNOON OVER THE WEST.
HOWEVER...LACK OF LOW LEVEL LIFT OR FOCUSING MECHANISM SHOULD
MINIMIZE POTENTIAL FOR -FZDZ. SOME LIGHT SNOW WILL LINGER OVER THE
ERN CWA TONIGHT AS THE SFC-850 MB TROUGH SLOWLY PIVOTS TO THE NORTHEAST.
FRIDAY...MODELS WERE IN AGREEMENT THAT THE PCPN ASSOCIATED WITH A
SHORTWAVE MOVING FROM THE PAC THROUGH THE NRN PLAINS INTO THE MS
VALLEY AND SRN GREAT LAKES IS EXPECTED TO REMAIN SOUTH OF UPPER MI.
SOME ISOLATED LIGHT SNOW SHOWERS MAY BE POSSIBLE NEAR AN INVERTED
TROUGH AXIS INTO THE NRN CWA. AGAIN...-FZDZ MAY ALSO BE POSSIBLE BUT
PROBABILITIES REMAIN LOW.
SAT INTO SUN...THE NEXT MID LEVEL TROUGH IN THE PROGRESSIVE PATTERN
WILL MOVE INTO THE REGION BY LATE SAT. WAA AHEAD OF THE MID LEVEL
AND SFC TROUGH MAY BRING SOME LIGHT PCPN INTO THE WRN CWA. THE
MORE CONSISTENT ECMWF WAS PREFERRED FOR DETAILS WITH THE SYSTEM AS
THE GFS AND NAM HAVE AT TIMES SHOWED A STRONGER SHORTWAVE SWEEPING
THROUGH THE REGION THAT WOULD GENERATE SUBSTANTIAL PCPN AND BRING
MUCH GREATER DEEPENING OF THE SFC LOW. FALLING TEMPS AND BLUSTERY WNW
WINDS ARE EXPECTED BY SUN AFTERNOON BEHIND A STRONG COLD FRONT.
SUN NIGHT INTO TUE...AS THE PATTERN BRIEFLY AMPLIFIES...MUCH
COLDER AIR WILL POUR INTO THE WRN LAKES ON NW TO N WINDS DROPPING
850 MB TEMPS TO AROUND -20C. SUBTLE MODEL DIFFERENCES REMAIN WITH
THE PREVAILING WIND DIRECTION AS THE GFS REMAINS MORE TO THE NW
COMPARED TO THE NRLY DIRECTION DEPICTED BY THE ECMWF/GEM. SIGNIFICANT
LES REMAINS POSSIBLE WITH INTENSITY DROPPING OFF MON AS DEEPER
MOISTURE DEPARTS.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/...
A LOW PRESSURE SYSTEM MOVING S OF THE AREA TODAY WILL BRING -SN TO
ALL TAF SITES...RESULTING IN IFR CONDITIONS. LIFR CONDITIONS ARE
POSSIBLE AS WELL...ESPECIALLY AT KCMX...DURING PERIOD OF HEAVIEST
SNOW. IMPROVEMENT EXPECTED W TO E LATE MORNING/AFTN AS MAIN AREA OF
-SN EXITS. HOWEVER...IT MAY BE DIFFICULT TO GET RID OF THE LOWER
CIGS GIVEN LIGHT LOW-LEVEL WINDS AND THUS WEAK ADVECTION OF ANY
DRIER AIR AT THE LOW-LEVELS. SO...CIGS MAY REMAIN IFR OR ONLY RISE
SLIGHTLY TO LOW MVFR IN THE AFTN. IWD IS THE MOST LIKELY TO SEE
SIGNIFICANT IMPROVEMENT.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
A LOW PRESSURE SYSTEM OVER MN WILL MOVE EAST TODAY. ALTHOUGH WINDS
SHOULD STAY BELOW GALE FORCE...THEY WILL BECOME RATHER GUSTY OUT OF
THE SOUTHEAST WITH PERHAPS A GUST OR TWO CLOSE TO GALE FORCE. AFTER
ANOTHER LOW MOVES ACROSS THE LOWER LAKES ON FRIDAY...A WEAK RIDGE
BUILDS ACROSS LAKE SUPERIOR INTO SATURDAY BEFORE A STRONG LOW
DEVELOPS OVER THE PLAINS AND MOVES NORTH OF LAKE SUPERIOR FOR NEW
YEARS DAY. HIGH END NORTH-NORTHWEST GALES ARE POSSIBLE WITH THIS
SYSTEM INTO MONDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ014-
085.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
DISCUSSION...JLB
AVIATION...TITUS
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
550 AM EST THU DEC 29 2011
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG WRLY MID/UPPER LEVEL
FLOW INTO THE PAC NW AND WNW FLOW DOWNSTREAM FROM THE SRN CANADA AND
NRN PLAINS INTO THE GREAT LAKES. ONE SHEARED SHORTWAVE TROUGH WAS
LOCATED NORTH OF LAKE SUPERIOR AND ANOTHER WAS MOVING THROUGH SW MN.
AT THE SFC...A 997 MB LOW WAS LOCATED OVER SRN MN RESULTING IN S TO
SE WINDS ACROSS UPPER MICHIGAN. AN AREA OF SNOW FROM NE MN INTO WRN
LAKE SUPERIOR NW WI WITH VSBYS INTO THE 1-3SM RANGE WAS SUPPORTED BY
285K-290K ASCENT AHEAD OF A 850-700 MB TROUGH. ANY LAKE EFFECT/ENHANCED
SNOW OFF OF LAKE MICHIGAN WITH THE SRLY FLOW HAS BEEN MINIMAL WITH
ONLY A DUSTING AT MOST.
&&
.DISCUSSION...
TODAY AND TONIGHT...EXPECT THE AREA OF SNOW TO PROGRESS ACROSS UPPER
MICHIGAN TODAY. MODELS CONSENSUS QPF OF AROUND A TENTH OF AN INCH
WITH SNOW/WATER RATIO VALUES NEAR 15/1 WOULD RESULT IN SNOWFALL
AMOUNTS OF AN INCH OR TWO WHICH IS REASONABLE GIVEN 2G-3G/KG
MOISTURE AVBL NEAR 700MB DURING A 6 HOUR PERIOD OF STRONGER LIFT.
UNCERTAINTY REMAINS WITH REGARD TO LAKE ENHANCED SNOW POTENTIAL INTO
THE SE CWA. THE HIGHER RES MODELS HAVE BEEN OVERDOING PCPN WITH
BANDS OFF OF LAKE MICHIGAN SO FAR. HOWEVER...AS THE DEEPER MOISTURE
ARRIVES...EXPECT THAT THE LAKE CONTRIBUTION MAY ADD AN ADDITIONAL
1-2 INCHES TO SNOWFALL AMOUNTS. SINCE THE WINDS WERE BACKING MORE
SERLY AHEAD OF THE LOW...THE BEST LOW LEVEL CONV AND OVER WATER
TRAJECTORIES HAVE SHIFTED TO THE WEST. SO...HAVE CANCELLED THE ADVY
FOR LUCE COUNTY AND CONTINUED MENTION OF 2 TO 4 INCHES OF SNOW IN
THE ADVY FOR SCHOOLCRAFT COUNTY TODAY. MODELS SUGGEST THAT THE
DEEPER MOISTURE WILL QUICKLY DEPART THIS AFTERNOON OVER THE WEST.
HOWEVER...LACK OF LOW LEVEL LIFT OR FOCUSING MECHANISM SHOULD
MINIMIZE POTENTIAL FOR -FZDZ. SOME LIGHT SNOW WILL LINGER OVER THE
ERN CWA TONIGHT AS THE SFC-850 MB TROUGH SLOWLY PIVOTS TO THE NORTHEAST.
FRIDAY...MODELS WERE IN AGREEMENT THAT THE PCPN ASSOCIATED WITH A
SHORTWAVE MOVING FROM THE PAC THROUGH THE NRN PLAINS INTO THE MS
VALLEY AND SRN GREAT LAKES IS EXPECTED TO REMAIN SOUTH OF UPPER MI.
SOME ISOLATED LIGHT SNOW SHOWERS MAY BE POSSIBLE NEAR AN INVERTED
TROUGH AXIS INTO THE NRN CWA. AGAIN...-FZDZ MAY ALSO BE POSSIBLE BUT
PROBABILITIES REMAIN LOW.
SAT INTO SUN...THE NEXT MID LEVEL TROUGH IN THE PROGRESSIVE PATTERN
WILL MOVE INTO THE REGION BY LATE SAT. WAA AHEAD OF THE MID LEVEL
AND SFC TROUGH MAY BRING SOME LIGHT PCPN INTO THE WRN CWA. THE
MORE CONSISTENT ECMWF WAS PREFERRED FOR DETAILS WITH THE SYSTEM AS
THE GFS AND NAM HAVE AT TIMES SHOWED A STRONGER SHORTWAVE SWEEPING
THROUGH THE REGION THAT WOULD GENERATE SUBSTANTIAL PCPN AND BRING
MUCH GREATER DEEPENING OF THE SFC LOW. FALLING TEMPS AND BLUSTERY WNW
WINDS ARE EXPECTED BY SUN AFTERNOON BEHIND A STRONG COLD FRONT.
SUN NIGHT INTO TUE...AS THE PATTERN BRIEFLY AMPLIFIES...MUCH
COLDER AIR WILL POUR INTO THE WRN LAKES ON NW TO N WINDS DROPPING
850 MB TEMPS TO AROUND -20C. SUBTLE MODEL DIFFERENCES REMAIN WITH
THE PREVAILING WIND DIRECTION AS THE GFS REMAINS MORE TO THE NW
COMPARED TO THE NRLY DIRECTION DEPICTED BY THE ECMWF/GEM. SIGNIFICANT
LES REMAINS POSSIBLE WITH INTENSITY DROPPING OFF MON AS DEEPER
MOISTURE DEPARTS.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
AS NEXT LOW PRES SYSTEM APPROACHES FROM THE W...-SN WILL SPREAD
ACROSS THE AREA OVERNIGHT THRU THE MORNING...RESULTING IN VFR
CONDITIONS AT KIWD/KCMX/KSAW FALLING QUICKLY TO MVFR THEN IFR.
LIFR CONDITIONS ARE POSSIBLE AS WELL...ESPECIALLY AT KCMX...DURING
PERIOD OF HEAVIEST SNOW. IMPROVEMENT EXPECTED W TO E LATE
MORNING/AFTN AS MAIN AREA OF -SN EXITS. HOWEVER...IT MAY BE
DIFFICULT TO GET RID OF THE LOWER CIGS GIVEN LIGHT LOW-LEVEL WINDS
AND THUS WEAK ADVECTION OF ANY DRIER AIR AT THE LOW-LEVELS. SO...
CIGS MAY REMAIN IFR OR ONLY RISE SLIGHTLY TO LOW MVFR IN THE AFTN.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
A LOW PRESSURE SYSTEM OVER MN WILL MOVE EAST TODAY. ALTHOUGH WINDS
SHOULD STAY BELOW GALE FORCE...THEY WILL BECOME RATHER GUSTY OUT OF
THE SOUTHEAST WITH PERHAPS A GUST OR TWO CLOSE TO GALE FORCE. AFTER
ANOTHER LOW MOVES ACROSS THE LOWER LAKES ON FRIDAY...A WEAK RIDGE
BUILDS ACROSS LAKE SUPERIOR INTO SATURDAY BEFORE A STRONG LOW
DEVELOPS OVER THE PLAINS AND MOVES NORTH OF LAKE SUPERIOR FOR NEW
YEARS DAY. HIGH END NORTH-NORTHWEST GALES ARE POSSIBLE WITH THIS
SYSTEM INTO MONDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ014-
085.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...JLB
DISCUSSION...JLB
AVIATION...ROLFSON
MARINE...TITUS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
930 AM CST THU DEC 29 2011
.DISCUSSION...FORECAST CHALLENGE FOR UPDATE CONCERNS PCPN
CHANCES/PHASE AND TEMPERATURES.
CLEARING AND MODEST SNOW COVER ALLOWED TEMPERATURES TO DROP WELL IN
THE SINGLE DIGITS ACROSS THE NORTHERN VALLEY THIS MORNING. CLOUDS
WILL SPREAD ACROSS THE REGION TODAY HOWEVER WARM ADVECTION ACROSS
FAR NORTH WILL BE LIMITED. FOR THIS WILL NEED TO LOWER MINIMUMS A
BIT ACROSS THE FAR NORTH.
PCPN INITIATION AND PHASE WILL BE BIG CHALLENGE LATE THIS AFTERNOON
AND EVENING. WITH VERY LITTLE NEW DATA TO LOOK AT WILL NOT BE
ALTERING POPS/WEATHER FOR UPDATE. RUC DOES INDICATE MOST PCPN MAY
HOLD OFF TILL AFT 00Z HOWEVER NOT PICKING UP ON NARROW BAND ACROSS
WESTERN ND. PREFER TO SEE NEW MODEL DATA BEFORE MAKING ANY CHANGES.
&&
.AVIATION...VERY CHALLENGING FORECAST AND CONFIDENCE IS LOW. THERE
WILL LIKELY BE A PERIOD OF VFR CIGS OR CLEAR SKIES DURING THE
MORNING HOURS AND INTO THE AFTERNOON HOURS. HOWEVER...THERE IS A
DEVELOPING AREA OF LOW CIGS NORTH OF THE INTERNATIONAL
BORDER...AND NOT SURE WHAT IS GOING TO HAPPEN WITH THESE (COULD
CONTINUE TO GROW SOUTHWARD). IFR/MVFR CIGS (VSBY WITH -SN) WILL
APPROACH THE REGION DURING THE AFTERNOON HOURS AND CONTINUE INTO
THE EVENING HOURS.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&
$$
VOELKER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1016 AM EST THU DEC 29 2011
.SYNOPSIS...
A PAIR OF ALBERTA CLIPPERS WILL MOVE ACROSS THE GREAT LAKES TODAY
AND FRIDAY. A STRONG ARCTIC COLD FRONT IS LIKELY TO MOVE THROUGH
THE STATE ON NEW YEARS DAY. GUSTY WINDS...BITTERLY COLD AIR AND
LAKE EFFECT SNOW ARE EXPECTED AS THE COLD AIR RUSHES IN ACROSS THE
LAKES.
&&
.NEAR TERM /UNTIL 5 PM THIS AFTERNOON/...
RETURN FLOW WEST OF THE BOUNDARY LAYER RIDGE AXIS IS TOUCHING OFF
SOME VERY LIGHT PRECIP IN THE FORM OF SNOW OVER SOUTHWEST PA THIS
MORNING. MOST HIGH RESOLUTION LCL MODELS AND OPERATIONAL GFS/NAM
AND RUC HAVE NOT CAPTURED THIS...BUT LCL HRR AT LEAST HAS SOME QPF
PAINTED OVER WESTERN PORTIONS OF THE LAUREL HIGHLANDS BETWEEN 14Z
AND 16Z BEFORE DISSIPATING IT. TRACE AMOUNTS FROM FLURRIES SHOULD
BE INCONSEQUENTIAL THIS MORNING...BUT DID ADD SLIGHT CHC POPS FOR
THIS ALONG MY AREAS BORDERING KPBZ OVER THE LAUREL HIGHLANDS AND
FURTHER NORTH INTO THE NORTH CENTRAL MOUNTAINS.
AS UPPER SHORT WAVE DIVES DOWN OVER IA/WI EARLY THIS MORNING AND
TOWARDS THE OHIO VALLEY THIS AFTERNOON...A MAIN AREA OF WARM
ADVECTION PRECIPITATION WILL BREAK OUT ACROSS IL/OH AND CROSS INTO
PA LATE THIS AFTERNOON. OTHER THAN FLURRIES THIS MORNING INTO THIS
AFTERNOON SOUTHWEST...WEST AND NORTH...PRECIPITATION FROM THE MAIN
WAVE WILL HOLD OFF UNTIL AFTER 22Z.
HIGHS WILL BE A DEG OR TWO COOLER IN THE SE WITHOUT THE DOWNSLOPE
AND LESS SUNSHINE TODAY VS WED. TEMPS IN THE N WILL BE 5-7F BETTER
THAN WED DUE TO THE SRLY WIND/WAA.
&&
.SHORT TERM /5 PM THIS AFTERNOON THROUGH SATURDAY/...
WNW UPPER FLOW IS FAST WITH A 110KT JET STREAK FORCING THE LIFT TO
IT/S LEFT EXIT REGION...AND WILL MOVE JUST TO THE SOUTH OF THE
AREA BY MIDNIGHT. THE FLOW FLATTENS OUT A BIT AS THE MAIN WARM
ADVECTION MOVES OVER OUR NRN ZONES AND NY STATE THIS EVENING AND
OVERNIGHT. WILL RUN WITH ONLY HIGH CHC/LOW LIKELY POPS FOR THE NRN
TIER TONIGHT...AS PRECIP MAY NOT BE HEAVY ENOUGH TO MAKE ACCUMS OF
MORE THAN AN INCH THERE. POPS/CHC FOR SNOW FALL OFF PRETTY QUICKLY
TO THE SOUTH OF ROUTE 6 AND ARE SMALL BY THE TIME YOU REACH I-80.
TEMPS WILL PROBABLY FALL JUST A FEW DEGS FOR THE NIGHT WITH THE
CLOUDS AND SOME S WIND.
NEXT SHORT WAVE/CLIPPER WRAPS UP A BIT MORE THAN THE FIRST
ONE...WITH A MORE COHERENT TROUGH BEGINNING TO FORM OVER THE UPPER
MIDWEST ON FRI. SFC LOW DEEPENS NEAR 1000MB AS IT MOVES OVER LOWER
MI AND THE LOWER LAKES. THIS STORM WILL SPREAD ADDITIONAL
MOISTURE IN VERY QUICKLY ON FRIDAY AND ALLOW ONLY A BRIEF PERIOD
OF FAIR WEATHER IN THE MORNING. HOWEVER...WITH WARM AIR
OVERRUNNING THE COLD AIR AT THE SFC...SOUNDING PROFILES INDICATE
AT LEAST SOME THREAT FOR PATCHY FREEZING DRIZZLE OR BRIEF FREEZING
RAIN ACROSS MAINLY THE NORTHERN VALLEYS EARLY FRI MORNING. DO NOT
EXPECT ENOUGH COVERAGE TO GARNER AN ADVISORY AT THIS TIME...BUT
DID ADD THIS TO THE HWO. POPS WILL BE HIGHER FRI THAN THURS...BUT
THE TEMPS WILL RISE ENOUGH AHEAD OF THIS PSEUDO CLIPPER TO MAKE
MAINLY RAIN AFT 9 AM SOUTH OF I80. QPF WILL BE VERY LIGHT...THOUGH.
NRN MTS COULD SEE MOSTLY SNOW BUT WAA WORKS TEMPS HIGHER THERE AS
WELL...BUT THE COLD AIR WILL BE TOUGHER TO SCOUR OUT. WILL KEEP
ANY MENTIONS OF ACCUMS IN THE NCENT COS. MAXES ON FRI WILL TRY TO
GET INTO THE L50S IN THE S...BUT COULD STICK IN THE L-M 30S IN THE
FAR NRN VALLEYS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AFTER A BREAK ON SATURDAY...A STRONG ARCTIC COLD FRONT WILL BULLY
ITS WAY THROUGH THE AREA DURING NEW YEARS DAY. THIS FEATURE WILL
DEFINE THE LEADING WEDGE OF SOME MUCH COLDER AIR THAT WILL BRING
THE PUFFY COATS BACK OUT OF THE CLOSET FOR AT LEAST A FEW DAYS.
THE UPPER PATTERN WILL BECOME HIGHLY AMPLIFIED FOR THE FIRST FEW
DAYS OF THE NEW YEAR WITH THE AXIS OF THE TROUGH SWINGING RIGHT
THROUGH THE GREAT LAKES REGION. LONG TERM GUIDANCE COMING INTO
LINE WITH SIMILAR IDEAS ON MUCH COLDER AIR FROM MONDAY THROUGH MID
WEEK. -20C 850 TEMPS OVER THE STATE WOULD KEEP TEMPS AROUND THE 20
DEGREE MARK...GIVE OR TAKE A FEW DEPENDING ON CLOUD COVER.
SAVE FOR ANY CLIPPER TYPE SYSTEMS THAT MAY ENTER THE PICTURE IN
THIS DEEP TROUGH...LAKE EFFECT HOLD THE LIMITED CHANCE FOR
SNOWFALL DURING THIS PERIOD.
THE EURO MODEL STILL DEVELOPS A STORM SYSTEM AS THIS COLD POOL
MOVES OVER THE GULF STREAM BUT DOES SO WELL EAST OF THE SOLUTION
FROM 24 HOURS AGO...FAR OUT TO SEA.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
MVFR CIGS LINGERING IN HIGHER ELEVATIONS OF THE NW MTNS...WITH VFR
ELSEWHERE AT 12Z. CIGS WILL LIFT TO VFR AREAWIDE BY 14-15Z AS
WINDS TURN TO THE SOUTH AT AROUND 5 MPH FOR THE DAYLIGHT HOURS.
SHORTWAVE/CLIPPER SLIDES IN FROM THE WEST EARLY THIS
EVENING...SPREADING LOWER CIGS AND LIGHT SNOW BACK INTO MAINLY
HIGHER TERRAIN OF THE WEST BY EARLY EVENING...WHILE REMAINDER OF
THE AREA IS PRIMARILY VFR. INCREASING LOW LEVEL WINDS WHICH WILL
LEAD TO MARGINAL WIND SHEAR AT BFD AND JST OVERNIGHT.
A SLIGHTLY BETTER CHC OF SNOW OR RAIN SHOWERS FRI...AS A SECOND
CLIPPER SYSTEM MOVES THROUGH.
OUTLOOK...
FRI...MVFR/IFR MAINLY WESTERN AREAS WITH RAIN/SNOW SHOWERS.
SAT...MVFR NW MTNS. VFR ELSEWHERE.
SUN...MAINLY VFR.
SUN NIGHT-MON...MVFR POSS IN -SHSN. GUSTY WINDS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO/DEVOIR
SHORT TERM...DANGELO/DEVOIR
LONG TERM...TYBURSKI
AVIATION...RXR
AREA FORECAST DISCUSSION...UPDATED
NWS MORRISTOWN TN
937 AM EST THU DEC 29 2011
.DISCUSSION...
THE POSITION OF THE JET STREAM OVER THE UPPER MS VALLEY TO OHIO
VALLEY IS BRINGING CONSIDERABLY CLOUDINESS TO NORTHERN PORTIONS OF
THE AREA THIS MORNING. RUC AND NAM SHOW DECREASING CLOUD COVER
THROUGH THE AFTERNOON...BUT THE MORNING CLOUDS ARE KEEPING
TEMPERATURES LOWER THAN FORECAST SO FAR. WILL ISSUE AN UPDATE TO
ADJUST TEMPERATURES DOWNWARD IN THE NORTH...AND INCREASE CLOUD
COVER AS WELL.
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
DGS
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1220 PM EST THU DEC 29 2011
.AVIATION... / 18Z TAFS /
KIWX RADAR STILL INDICATING A FEW LIGHT SHOWERS/SPRINKLES MOVING
TOWARD THE KFWA AREA...NOT ANTICIPATING ANY VSBY OR CEILING
RESTRICTIONS WITH THIS SO WILL LEAVE OUT OF TAF TO BEGIN THE PERIOD.
GUSTY SOUTHWEST WINDS THIS AFTERNOON OTHERWISE VFR CONDITIONS TO
PREVAIL AT BOTH SITES UNTIL FRIDAY MORNING WHEN -RA WITH NEXT
CLIPPER SYSTEM EXPECTED TO ARRIVE AND BRING WITH IT MVFR CIGS/VSBYS.
&&
.PREV DISCUSSION... /ISSUED 355 AM EST THU DEC 29 2011/
SHORT TERM... / TODAY THROUGH FRIDAY NIGHT /
08Z SFC ANALYSIS SHOWS A SFC LOW NEAR MSP WITH A WARM FRONT
EXTENDING SE INTO EASTERN IA AND WC IL. THE ASSOCIATED LOW
AMPLITUDE SHORTWAVE OVER THE UPPER MIDWEST WILL SHEAR OUT TOWARDS
THE CENTRAL GREAT LAKES TODAY ALLOWING THE WARM FRONT TO SURGE
NEWD INTO THE SRN GREAT LAKES. RATHER MODEST
OVERRUNNING/ISENTROPIC UPGLIDE EXPECTED JUST AHEAD OF THIS WARM
FRONT THIS MORNING INTO EARLY THIS AFTERNOON (40 KNOTS OF CROSS
ISOBARIC FLOW ON THE I290 SFC). UPSTREAM OBS/MOSAIC RADAR AND THE
BULK OF 00Z GUIDANCE SUGGEST THAT NORTHERN AREAS MAY SEE A BRIEF
PERIOD (AN HOUR OR TWO) OF VERY LIGHT PCPN THIS MORNING INTO EARLY
THIS AFTN...WITH THE BETTER CHANCES FOR MEASURABLE PCPN (A COUPLE
HUNDREDTHS AT BEST) BEING ACROSS THE NORTH/NORTHEAST WITH MAINLY
VIRGA SOUTHWEST. LATEST RUC SOUNDINGS AND SFC OBS CONTINUE TO
SUPPORT A POSSIBLE LIGHT MIX OF FREEZING DRIZZLE/SNOW TO
START...LIKELY TRANSITIONING TO A BRIEF PERIOD OF DRIZZLE. ANY
FREEZING DRIZZLE/RAIN BTW 12-15Z MAY CREATE A FEW SLICK SPOTS ON
AREA ROADS...MAINLY NORTH OF ROUTE 6. OTHERWISE...EXPECT WINDS
WILL PICK UP AND VEER BEHIND THE FRONTAL BOUNDARY WITH GUSTS OF
20-25 KNOTS POSSIBLE.
A MUCH MORE VIGOROUS SHORTWAVE NOW ACROSS THE PAC NW WILL DIG INTO
THE MID MS VALLEY AND NRN OH VALLEY BY LATER TONIGHT AND FRIDAY.
GFS/ECMWF AGREE ON 120-140 METER 500 MB HEIGHT FALLS WITH THIS
FEATURE SUPPORTING A RATHER HEALTHY LOW LVL RESPONSE AND THETA-E
ADV INTO THE AREA WITH PCPN FOCUSING ALONG A DEEPENING BAROCLINIC
ZONE. A MODEL CONSENSUS FAVORS THE NORTHERN HALF OF THE FA FOR
BEST CHANCES FOR MEASURABLE RAINFALL. AMOUNTS ARE FCST TO RANGE
BETWEEN 0.20" AND 0.50" HERE. HIRES GUIDANCE IS A LITTLE FARTHER
SOUTH WITH THE TRACK OF THIS SYSTEM SO DID CONTINUE WITH
CHC/SLIGHT WORDING FOR SNOW IN THE FAR NORTH...WITH AREAS JUST
NORTH OF THE FA IN A GOOD POSITION FOR A MODERATE SNOWFALL.
OTHERWISE...TEMPS ARE FCST TO BE ABOVE NORMAL THIS PERIOD WITH
ONLY MINOR TWEAKS MADE.
LONG TERM...
OVERALL LARGE SCALE PATTERN STILL EXPECTED TO BECOME MORE AMPLIFIED
THROUGH THE LONG TERM WITH BRIEF ARCTIC INTRUSION STILL EXPECTED
LATTER HALF OF WEEKEND INTO NEXT WEEK. MEDIUM RANGE MODELS REMAIN IN
GOOD AGREEMENT ON LARGE SCALE WITH DIFFERENCES CONTINUING IN THE
DETAILS. CR ALLBLEND LOADED AND COLLABORATED SOME TWEAKS TO TEMPS
AND POPS.
A QUIET START EXPECTED ON SATURDAY WITH WARM AIR ADVECTION AHEAD OF
FIRST COLD FRONT AND TEMPERATURES RISING WELL ABOVE NORMAL FOR LATE
DECEMBER. SHOULD SEE 40S ACROSS ENTIRE AREA FOR HIGHS WITH 50S NOT
OUT OF QUESTION SOUTH AND WEST. WARM AIR ADVECTION CONTINUES FIRST
HALF OF SATURDAY NIGHT WITH TEMPS STEADY OR SLOWLY RISING UNTIL
INITIAL FRONTAL PASSAGE LATE. HAVE TRIED TO DETAIL THIS SCENARIO IN
HOURLY GRIDS WITH STEADY TEMPS THROUGH 06Z THEN A SLOW FALL TOWARD
12Z.
DETAIL DIFFERENCES AND COMPLICATIONS IN FORECAST BEGIN IN THIS
SATURDAY NIGHT INTO SUNDAY TIME FRAME WITH STRENGTH AND TIMING OF
COLD AIR ADVECTION AND ANY ASSOCIATED PCPN. 850MB TEMPS BEGIN TO
FALL AFTER 06Z SUNDAY WITH 1000-850MB THICKNESSES FOLLOWING. MODELS
SHOWING LITTLE IN WAY OF PCPN WITH THIS FRONT GIVEN POSITIVELY
TILTED UPPER SYSTEM AND NO STRONG MOISTURE SURGE AHEAD OF IT.
DEEPENING SURFACE LOW REMAINS WELL NORTH OF AREA WITH ONLY SUBTLE
INDICATIONS OF SECONDARY LOW DEVELOPMENT ALONG FRONT BY A FEW
MODELS. HAVE THEREFORE ALLOWED LOW CHANCE POPS TO RIDE SAT NIGHT AND
SUNDAY MORNING. SUNDAY BEGINNING TO LOOK DRY IN WAKE OF INITIAL COLD
FRONT WITH SOME SUNSHINE EVEN POSSIBLE IN DRY SLOT BEFORE SECONDARY
ARCTIC FRONT LATER IN THE DAY. IF THIS OCCURS...FALLING TEMPS EARLY
IN THE MORNING MAY BECOME STEADY OR EVEN RISE A FEW DEGREES BEFORE
SECONDARY FRONT BRINGS MUCH COLDER AIR IN DURING THE AFTERNOON. FOR
NOW HAVE CHOSEN TO GO WITH SLOWLY FALLING TEMPS DURING THE DAY GIVEN
TEMPS LOOK TO FALL IN THE AFTERNOON REGARDLESS.
WITH ARCTIC INTRUSION SUNDAY NIGHT WILL SEE BEST LAKE EFFECT SNOW
POTENTIAL OF THE SEASON AS DELTA T VALUES CLIMB WITH SURFACE TO
850MB WELL INTO LOWER 20S. SURFACE TO 700MB DELTA T VALUES REACH
CRITICAL 30C THRESHOLD WHICH IS A GOOD INDICATOR OF HEAVY SNOW
POTENTIAL. LIMITING FACTOR CONTINUES TO BE MOISTURE PROFILES BUT
MEDIUM RANGE MODELS ARE SHOWING SOME DECENT SYNOPTIC MOISTURE LATE
SUNDAY NIGHT THROUGH MONDAY WHICH WOULD SUPPORT A PERIOD OF HEAVY
LAKE EFFECT SNOW BANDS. NORTHWEST FLOW AND WIND FIELD SUGGEST
MULTI-BANDED EVENT WHICH MAKES PINNING DOWN AMOUNTS AND LOCATIONS
DIFFICULT AT THIS TIME PROJECTION. HAVE BUMPED NW FETCH FAVORED
AREAS INTO LIKELY CATEGORY FOR NOW. HEADLINES POSSIBLE LATER THIS
WEEKEND INTO EARLY NEXT WEEK AS MOISTURE PROFILES BECOME BETTER
DEFINED BY HIGHER RESOLUTION MODELS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
&&
$$
SHORT TERM...STEINWEDEL
LONG TERM...LASHLEY
AVIATION...LOGSDON
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1158 AM CST THU DEC 29 2011
.AVIATION...
CURRENTLY LOW PRESSURE IS SLIDING SOUTHEASTWARD ACROSS SOUTHERN
WISCONSIN WITH IFR CEILINGS OVER CENTRAL MINNESOTA. VFR CONDITIONS
ARE IN PLACE OVER EASTERN IOWA. IFR CEILINGS IN CENTRAL MINNESOTA
ARE FORECAST TO REMAIN TO THE NORTH AND EAST OF
KCID...KDBQ...KMLI...AND KBRL THIS AFTERNOON. CLOUD HEIGHTS WILL
SLOWLY LOWER AS ANOTHER FAST MOVING STORM SYSTEM APPROACHES AND
MOVES THROUGH THE REGION TONIGHT. RAIN IS EXPECTED TO DEVELOP BY
06 UTC WITH MVFR CEILINGS AT KCID...KDBQ...AND KMLI. KMLI IS ON
THE SOUTHERN EDGE OF THE HEAVIER PRECIPITATION SO WENT WITH VCSH
AFTER 14 UTC. CURRENTLY...RAIN IS EXPECTED TO TRANSITION TO SNOW
AT KDBQ AFTER 12 UTC. ANY LINGERING PRECIPITATION WILL EXIT INTO
WESTERN ILLINOIS BY 18 UTC WITH MVFR CEILINGS CONTINUING THROUGH
18 UTC AT ALL TAF SITES.
..JH/DC..
&&
PREV DISCUSSION... /ISSUED 652 AM CST THU DEC 29 2011/
UPDATE...
A FEW SHRA/S HAVE DEVELOPED FROM NEAR QUAD CITIES S/E WITHIN AREA
OF MID LEVEL INSTABILITY AHEAD OF VORT MAX. UPDATED TO ADD ISOLD
MENTION AND SHOULD BE OUT OF CWA NEXT 1-2 HRS. NEXT CONCERN IS
CLOUD TRENDS. LEADING EDGE OF STRATUS HAS DISSIPATED OVER SOUTHERN
MN AND NOTICING PAST FEW HRS OF CIG TRENDS FROM RUC BACKUP MODEL
KEEPS LOW CLOUDS TO N/W OF CWA TDY. THIS LOOKS REASONABLE GIVEN
RECENT TRENDS PLUS THE ADDITIONAL RAPID EROSION TO STRATUS OVER ND
DUE TO WARM ADVECTION ALOFT. WILL BE UPDATING TO BE MORE OPTIMISTIC
WITH SKY COVER NORTH HALF AND TWEAK MAXES UP A COUPLE DEGS.
PREV DISCUSSION... /ISSUED 411 AM CST THU DEC 29 2011/
SYNOPSIS...
STARTING OUT THIS AM WITH TEMPS THAT ALREADY AT OR 5+ DEGS ABOVE NORMAL
HIGHS. ALWAYS A GREAT SIGN AND HARBINGER OF WHAT IS TO COME TDY.
QUASI-ZONAL FLOW FULL OF ENERGY EARLY THIS AM. WATER VAPOR IMAGERY AND
PROFILERS DEPICT SHORTWAVE NEAR PICKLE LAKE ONTARIO (CYPL) WITH
SECONDARY WAVE FURTHER SOUTH NEAR LACROSSE WI... BOTH SLIDING E/SE.
ATTENDANT SFC LOW WAS LOCATED CLOSE TO SAINT CLOUD MN WITH COLD FRONT
EXTENDING WNWD INTO NORTHERN SD WHILE WARM FRONT WAS DRAPED SEWD INTO
EASTERN IA. WARM ADVECTION WING WITH JUST TRACE AMOUNTS OF PCPN PASSING
QUICKLY THROUGH NORTHERN IL. MOST OBS THIS FAR SOUTH HAVE BEEN REPORTING
SPRINKLES BUT A COUPLE OF QUESTION MARKS SHOWING ON SOME ASOS NEAR WI/IL
BORDER INTO SOUTHERN WI AND SO CANT RULE OUT SOME FLAKES OR EVEN ICE
PELLETS BUT NO GROUND TRUTH REPORTS. THIS WILL BE EXITING SHORTLY WITH
SKIES CLEARING INTO EASTERN IA IN WAKE OF WARM ADVECTION. SATL SHOWS
A LARGE AREA OF LOW CLOUDS OVER ND... FAR NORTHEAST SD AND WESTERN MN ON
BACKSIDE OF SFC LOW IN LOW LEVEL COLD ADVECTION WHICH HAVE BEEN SLIDING
SEWD. MEANWHILE... NEXT BARRAGE OF ENERGY IN VERY ENERGETIC PACIFIC WAVE
TRAIN PLOWING THROUGH PACIFIC NW AND NORTHERN ROCKIES... AND ITS THIS
ENERGY THAT WILL AID IN BRINGING PCPN TO PORTIONS OF THE REGION TNGT-FRI.
SHORT TERM...TODAY AND TONIGHT...
EYES ARE POINTED NW EARLY THIS AM. SFC LOW OVER CENTRAL MN TO DIVE E/SE
THROUGH SOUTHERN WI TDY WITH TRAILING COLD FRONT SWEEPING ACROSS THE
CWA. THUS... WARM ADVECTION ON GUSTY SW WINDS TO START OFF WILL
EVENTUALLY BE REPLACED WITH COLD ADVECTION ON GUSTY W/NW WINDS. BEST
COLD ADVECTION PROGGED NORTH THIRD TO HALF OF CWA WHERE ALSO EXPECT TO SEE
SOME STRATUS TURNING SKIES FROM SUNNY TO PT-MOCLDY. TEMPS EVERYWHERE WELL
ABOVE NORMAL BY CLOSE TO 15+ DEGS... WITH COOLEST READINGS NORTH WHERE WENT
WITH AROUND 40/L40S DUE TO ANTICIPATION OF LOW CLOUDS BY MID-LATE AM. FROM
THERE ON SOUTH TEMPS WARMING WELL INTO THE 40S WITH 50S OVER SE IA... WCNTRL
IL AND NE MO.
TNGT... ANOTHER DOUBLE BARREL ENERGY COMPLEX EXPECTED TO SHIFT FROM THE
PLAINS INTO UPPER MIDWEST. ROBUST WARM ADVECTION TO GENERATE PCPN THAT WILL
MOVE ACROSS MUCH OF AREA BY MID-LATE EVE AND OVRNGT ESPECIALLY NORTH
OF KOTM-KBRL LINE. FCST SOUNDINGS AND LATEST SUITE OF SREF PTYPE PROBS ALL
SUPPORT PCPN WILL BE RAIN. UKMET AND ECMWF STRONGER WITH ENERGY RESULTING IN
DEEPER SFC LOW FOR EVEN WARMER DRAW AGAIN SUPPORTING RAIN AS THEY SHOW H85
LOW MOVING INTO NE IA 12Z FRI... PLACING BETTER SNOW CHCS NORTH OR LEFT OF THE
H85 LOW TRACK. QPF AMOUNTS WILL BE LIGHT AND GENERALLY A TENTH OR TWO AT MOST.
TEMPS WILL DROP OFF A BIT EARLY THIS EVE THEN BECOME STEADY AND SLOWLY RISE
WITH ONSET OF LOW LEVEL WARM ADVECTION. ..05..
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
FRIDAY...STILL SOME VARIANCE BETWEEN THE 00Z MODEL RUNS INTO FRI
WITH HANDLING AND DEVELOPMENT OF THE PASSING WAVE COMPLEX. BUT
WITH THE PROGRESSIVE NATURE OF THE CURRENT REGIME PATTERN WE HAVE
BEEN IN THIS WEEK AND LOOKING AT UPPER JET DYNAMICS THROUGH FRI
NIGHT... FEEL THE 00Z RUN GFS SOLUTION THE ONE TO FOLLOW FOR NOW
THIS PERIOD. ALSO PREFER THE FURTHER NORTH LOW TO MID LEVEL WAVE
PROGRESSION ACRS THE REGION IN LINGERING POSITIVE AO. THIS
ACCEPTED GFS SOLUTION SUGGESTS BULK OF ANY PRECIP SHIELD
ASSOCIATED WITH THE PASSING LOW WILL BE ON THE MOVE OUT OF THE DVN
CWA FRI MORNING AFTER 12Z. WILL WALK OUT PRECIP IN THE MORE WITH
LIKELY POPS IN THE FAR NORTHEAST... AND LESSER CHC POPS FURTHER TO
THE WEST AND SOUTH. IT ALSO APPEARS IN-WRAPPING LLVL COLD CONVEYOR
OR TOP-DOWN COOLING ENOUGH FOR A CHANGE OVER TO SNOW WILL OCCUR
AFTER THE BULK OF ANY MEASURING PRECIP EXITS THE AREA AS WELL. BUT
PROJECTED THERMAL PROFILES ARE CLOSE THROUGH 15Z FRI ALONG AND
NORTH OF THE HWY 20 CORRIDOR AND WILL MENTION A MIX IN THOSE AREAS
BUT WITH LITTLE IF ANY SNOW ACCUM. LOW TO MID LEVEL DRYING/RH
DECREASE LATE MORNING THOUGH MIDDAY AS LOW CENTER PASSES...THEN
SYSTEM WRAP AROUND STRATOCU ENGULFS MUCH OF THE CWA FRI AFTERNOON
INTO THE EVENING. EXTENT OF PRECIP POTENTIAL IN THIS WRAP AROUND
DECK UNCERTAIN ALONG WITH ADEQUATE MOISTURE DEPTH FOR MEASURABLE.
FOR NOW WILL JUST GO WITH A SLIGHT CHC OF LIGHT RAIN OR LIGHT SNOW
IN THE FAR NORTH FRI AFTERNOON...BUT IT MAY BE NOT MUCH MORE THAN
FLURRIES OR SPRINKLES. FRI HIGHS RANGING FROM AROUND 40 IN THE FAR
NORTH..TO NEAR 50 IN THE FAR SOUTH. THEN EXPECT THE CLOUDS TO
CLEAR TO THE EAST FRI NIGHT WITH SFC WIND DROP OFF WITH PASSING
SFC RIDGE LOBE. LOWS IN THE UPPER 20S TO LOWER 30S FOR NOW BUT IT
MAY BE COOLER DEPENDING ON IF RETURN FLOW CAN COMMENCE TOWARD SAT
MORNING IN TIME TO HALT THE TEMP DROP-OFF ESPECIALLY WEST OF THE
MS RVR.
SATURDAY AND SUNDAY...LOOKING AT THE LATEST 00Z RUN MEDIUM RANGE
MODELS AND WARM UP POTENTIAL AHEAD OF A SUBSTANTIAL IMPULSE TRYING TO
PHASE OVER THE MID CONUS ON SAT...DURATION OF THE WARM TONGUE
AND MIXING DEPTH STILL AT QUESTION ENOUGH TO FUEL THE ADVERTISED DAY
WELL IN THE 50S. WILL MAKE ONLY MINOR ADJUSTMENTS TO SAT HIGHS FOR
NOW AS STILL SOMEWHAT HESITANT TO GO CRAZY WITH THE FULL WARM UP
POTENTIAL. BUT EVEN WITH THE CURRENT PROJECTED THERMAL PROFILES AND
FCST SOUNDINGS...JUST MIXING UP TO AROUND H9 MB/INTO BASE OF A VERY
PRONOUNCED WARM WEDGE ALOFT/INVERSION CENTERED AROUND H85 MB...HIGHS
WOULD BE IN THE MID 50S WITH A FEW LOCATIONS PUSHING THE UPPER 50S IN
THE SOUTHWESTERN CWA. THE MODELS THEN REALLY START TO DIVERGE NEW
YEARS EVE/SAT NIGHT WITH RESPECT TO CONTINUED DEVELOP OF A L/W TROF
AND ASSOCIATED DEEPENING LLVL CYCLONE OVER THE UPPER MIDWEST AND
NORTHWESTERN GRT LKS. BUT THE GENERAL ENSEMBLES SUGGEST THAT THE
DVN CWA WILL REMAIN DRY SAT NIGHT AND MILD THROUGH MIDNIGHT/HELD UP
WELL IN THE 40S BEFORE IN-SWIRLING COLD PUSH MAKES IT ACRS THE AREA
FROM NW-TO-SE AFTER 09Z SUNDAY. STILL SOME DETAILS TO REFINE WITH
THIS PERIOD OVER THE NEXT 24-36 HRS OF MODEL RUNS. AS FOR NEW YEARS
DAY SUNDAY...A WINDY RAW DAY WITH MORNING HIGHS AND THEN FALLING
TEMPS AS NORTHWEST SFC WINDS GUST OVER 30 MPH IN ROBUST CAA REGIME
UNDER AMPLIFYING PATTERN. THE ECMWF STILL THE MOST DEVELOPED WITH
HIGH AMPLITUDE NEAR MERIDIONAL FETCH DEVELOPING ACRS THE WESTERN GRT
LKS BY MONDAY MORNING. H85 TEMPS BY 12Z MON IN NEGATIVE MID TEENS C
AND LOWS SUNDAY NIGHT PROBABLY WELL DOWN IN THE TEENS DESPITE
ONGOING MIXING WINDS OF 15-25 MPH EVEN AT NIGHT. WILL KEEP SUNDAY
DRY BUT IN SUCH A REGIME WOULD EXPECT COL AIR STRATUS TO BLANKET THE
AREA ALONG WITH SOME EMBEDDED FLURRIES.
MONDAY THROUGH WEDNESDAY...WILL KEEP HIGH AMPLITUDE ARCTIC AIRMASS
DUMP INTO THE MIDWEST GOING MON AND MON NIGHT. MONDAY HIGHS
PROBABLY NOT TO GET OUT OF THE LOW TO MID 20S WITH ONGOING GUSTY
NORTHWEST WINDS OF 20-30 MPH AND HIGHER GUSTS. SFC RIDGE LOBE
SLIDING ACRS THE CWA...SFC WIND DECOUPLE AND STRATUS CLEAR OFF COULD
FOSTER SINGLE DIGIT LOWS OVER SOME PORTIONS OF THE DVN CWA BY TUE
MORNING EVEN OVER SNOWCOVER-LESS TERRAIN. AGAIN WILL GO DRY IN THE
GRIDS ON MONDAY BUT WOULD BET SOME CAA FLURRIES CONTINUING TO GET
MILKED OUT OF WHATEVER MOISTURE THERE IS ACRS THE AREA. LONGER RANGE
SIGNALS SUGGEST THE FLOW WILL TRY TO FLATTEN OUT AGAIN TOWARD MID
NEXT WEEK AS ARCTIC OSCILLATION/AO PROGS MIGRATE BACK TOWARD THE
POSITIVE. BUT THERMAL MODERATION INTO TUE TO BE SLOW AND MORE
REALIZED BY NEXT WED WITH HIGHS RETURNING TO THE MID AND UPPER 30S.
THIS PROCESS MAY BE AIDED BY A WARM DRAW TO THE SOUTH OF CLIPPER TYPE
SYSTEM DROPPING FROM SASKATCHEWAN TO WI SOMETIME DURING THIS TUE INTO
WED PERIOD. ..12..
AVIATION... /ISSUED 1137 PM CST WED DEC 28 2011/
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1244 PM EST THU DEC 29 2011
UPDATED AVIATION DISCUSSION FOR 18Z TAFS
.UPDATE...
LIGHT SNOW HAS SPREAD ACROSS THE AREA NORTH OF SFC LOW OVER SOUTHERN
WI. SNOW HAS BEEN HEAVIER OVER SOUTH CENTRAL UPPER MICHIGAN AND ALSO
OVER LK SUPERIOR OVR KEWEENAW PENINSULA. SO FAR...HIGHEST AMOUNTS
WITH THE SYSTEM HAVE BEEN LESS THAN AN INCH. SE BLYR WINDS OFF LK
MICHIGAN WILL CONTRIBUTE TO INCREASING LAKE ENHANCED SNOW FOR DELTA
COUNTY AND SCHOOLCRAFT COUNTY THIS AFTN. NOT ALL THAT COLD AT H85 BUT
INVERSION TOP TEMPS ARE SLIGHTLY COLDER...AROUND -8C...LEADING TO
DELTA T/S AROUND 13C. SCNTRL UPR MI IS ALSO WHERE RUC INDICATES
PERIOD OF H85 THETA-E ADVECTION TO ENHANCE THE SNOW. OPTED TO INCLUDE
DELTA COUNTY IN SNOW ADVY FOR AFTN. TOTAL SNOW AMOUNTS WILL BE A
STRETCH TO REACH 4 INCHES FOR THE AFTN...BUT TOTALS IN THE 2 TO 4
INCH RANGE WITH LOWER VSBY...DOWN TO 1/2SM IN HEAVIER SNOW...SEEMS TO
JUSTIFY PUTTING DELTA INTO THE ADVY. EXPECT HEAVIER SNOW TO CEASE
BY LATE AFTN OR EARLY EVENING AS BETTER THETA-E ADVECTION DIMINISHES
TO THE EAST AS MAIN SHORTWAVE MOVES OUT OF THE AREA.
OTHER SPOT TO WATCH WILL BE KEWEENAW AS SIMILAR SETUP IS PRESENT.
SHEAR IN LOWEST 2KFT IS MORE NOTED WITH ESE WINDS AT SFC AND MORE
SRLY WINDS TOWARD 925MB PER MQT VWP. HIGHER TERRAIN OF KEWEENAW
COUNTY IS ORIENTED MORE WEST-TO-EAST SO WITH THE SOUTHERLY WINDS IN
LOW-LEVELS THERE IS MORE OF AN UPSLOPE COMPONENT THERE COMPARED TO
HOUGHTON COUNTY. COUNTY SHERIFF REPORTS A COUPLE INCHES THUS FAR OVR
HIGHER TERRAIN. SINCE HEAVIER SNOW MAY LAST A FEW HOURS LONGER BASED
ON STRONGER H85 THETA-E ADVECTION...WILL PUT ADVY UP FOR KEWEENAW
COUNTY FOR THE AFTN.
&&
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG WRLY MID/UPPER LEVEL
FLOW INTO THE PAC NW AND WNW FLOW DOWNSTREAM FROM THE SRN CANADA AND
NRN PLAINS INTO THE GREAT LAKES. ONE SHEARED SHORTWAVE TROUGH WAS
LOCATED NORTH OF LAKE SUPERIOR AND ANOTHER WAS MOVING THROUGH SW MN.
AT THE SFC...A 997 MB LOW WAS LOCATED OVER SRN MN RESULTING IN S TO
SE WINDS ACROSS UPPER MICHIGAN. AN AREA OF SNOW FROM NE MN INTO WRN
LAKE SUPERIOR NW WI WITH VSBYS INTO THE 1-3SM RANGE WAS SUPPORTED BY
285K-290K ASCENT AHEAD OF A 850-700 MB TROUGH. ANY LAKE EFFECT/ENHANCED
SNOW OFF OF LAKE MICHIGAN WITH THE SRLY FLOW HAS BEEN MINIMAL WITH
ONLY A DUSTING AT MOST.
&&
.DISCUSSION...
TODAY AND TONIGHT...EXPECT THE AREA OF SNOW TO PROGRESS ACROSS UPPER
MICHIGAN TODAY. MODELS CONSENSUS QPF OF AROUND A TENTH OF AN INCH
WITH SNOW/WATER RATIO VALUES NEAR 15/1 WOULD RESULT IN SNOWFALL
AMOUNTS OF AN INCH OR TWO WHICH IS REASONABLE GIVEN 2G-3G/KG
MOISTURE AVBL NEAR 700MB DURING A 6 HOUR PERIOD OF STRONGER LIFT.
UNCERTAINTY REMAINS WITH REGARD TO LAKE ENHANCED SNOW POTENTIAL INTO
THE SE CWA. THE HIGHER RES MODELS HAVE BEEN OVERDOING PCPN WITH
BANDS OFF OF LAKE MICHIGAN SO FAR. HOWEVER...AS THE DEEPER MOISTURE
ARRIVES...EXPECT THAT THE LAKE CONTRIBUTION MAY ADD AN ADDITIONAL
1-2 INCHES TO SNOWFALL AMOUNTS. SINCE THE WINDS WERE BACKING MORE
SERLY AHEAD OF THE LOW...THE BEST LOW LEVEL CONV AND OVER WATER
TRAJECTORIES HAVE SHIFTED TO THE WEST. SO...HAVE CANCELLED THE ADVY
FOR LUCE COUNTY AND CONTINUED MENTION OF 2 TO 4 INCHES OF SNOW IN
THE ADVY FOR SCHOOLCRAFT COUNTY TODAY. MODELS SUGGEST THAT THE
DEEPER MOISTURE WILL QUICKLY DEPART THIS AFTERNOON OVER THE WEST.
HOWEVER...LACK OF LOW LEVEL LIFT OR FOCUSING MECHANISM SHOULD
MINIMIZE POTENTIAL FOR -FZDZ. SOME LIGHT SNOW WILL LINGER OVER THE
ERN CWA TONIGHT AS THE SFC-850 MB TROUGH SLOWLY PIVOTS TO THE NORTHEAST.
FRIDAY...MODELS WERE IN AGREEMENT THAT THE PCPN ASSOCIATED WITH A
SHORTWAVE MOVING FROM THE PAC THROUGH THE NRN PLAINS INTO THE MS
VALLEY AND SRN GREAT LAKES IS EXPECTED TO REMAIN SOUTH OF UPPER MI.
SOME ISOLATED LIGHT SNOW SHOWERS MAY BE POSSIBLE NEAR AN INVERTED
TROUGH AXIS INTO THE NRN CWA. AGAIN...-FZDZ MAY ALSO BE POSSIBLE BUT
PROBABILITIES REMAIN LOW.
SAT INTO SUN...THE NEXT MID LEVEL TROUGH IN THE PROGRESSIVE PATTERN
WILL MOVE INTO THE REGION BY LATE SAT. WAA AHEAD OF THE MID LEVEL
AND SFC TROUGH MAY BRING SOME LIGHT PCPN INTO THE WRN CWA. THE
MORE CONSISTENT ECMWF WAS PREFERRED FOR DETAILS WITH THE SYSTEM AS
THE GFS AND NAM HAVE AT TIMES SHOWED A STRONGER SHORTWAVE SWEEPING
THROUGH THE REGION THAT WOULD GENERATE SUBSTANTIAL PCPN AND BRING
MUCH GREATER DEEPENING OF THE SFC LOW. FALLING TEMPS AND BLUSTERY WNW
WINDS ARE EXPECTED BY SUN AFTERNOON BEHIND A STRONG COLD FRONT.
SUN NIGHT INTO TUE...AS THE PATTERN BRIEFLY AMPLIFIES...MUCH
COLDER AIR WILL POUR INTO THE WRN LAKES ON NW TO N WINDS DROPPING
850 MB TEMPS TO AROUND -20C. SUBTLE MODEL DIFFERENCES REMAIN WITH
THE PREVAILING WIND DIRECTION AS THE GFS REMAINS MORE TO THE NW
COMPARED TO THE NRLY DIRECTION DEPICTED BY THE ECMWF/GEM. SIGNIFICANT
LES REMAINS POSSIBLE WITH INTENSITY DROPPING OFF MON AS DEEPER
MOISTURE DEPARTS.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/...
A LOW PRESSURE SYSTEM MOVING S OF THE AREA EARLY AFTN WILL BRING -SN
AND IFR CONDITIONS TO KCMX/KSAW. LIGHT SNOW HAS ALREADY DIMINISHED
AT KIWD. EVEN ONCE THE SNOW ENDS...COULD BE DIFFICULT TO GET RID OF
THE LOWER CIGS GIVEN LIGHT LOW-LEVEL WINDS AND THUS WEAK ADVECTION
OF ANY DRIER AIR AT THE LOW-LEVELS. EXPECT IFR CIGS TO POSSIBLY
LINGER ALL NIGHT AT KCMX WITH WINDS COMING OFF OF LK SUPERIOR.
EXPECT IMPROVEMENT AT KIWD/KSAW TO AT LEAST MVFR.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
A LOW PRESSURE SYSTEM OVER MN WILL MOVE EAST TODAY. ALTHOUGH WINDS
SHOULD STAY BELOW GALE FORCE...THEY WILL BECOME RATHER GUSTY OUT OF
THE SOUTHEAST WITH PERHAPS A GUST OR TWO CLOSE TO GALE FORCE. AFTER
ANOTHER LOW MOVES ACROSS THE LOWER LAKES ON FRIDAY...A WEAK RIDGE
BUILDS ACROSS LAKE SUPERIOR INTO SATURDAY BEFORE A STRONG LOW
DEVELOPS OVER THE PLAINS AND MOVES NORTH OF LAKE SUPERIOR FOR NEW
YEARS DAY. HIGH END NORTH-NORTHWEST GALES ARE POSSIBLE WITH THIS
SYSTEM INTO MONDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ013-
014-085.
WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ001.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SYNOPSIS...JLB
DISCUSSION...JLB
AVIATION...JLA
MARINE...TITUS
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1133 AM EST THU DEC 29 2011
.UPDATE...
LIGHT SNOW HAS SPREAD ACROSS THE AREA NORTH OF SFC LOW OVER SOUTHERN
WI. SNOW HAS BEEN HEAVIER OVER SOUTH CENTRAL UPPER MICHIGAN AND ALSO
OVER LK SUPERIOR OVR KEWEENAW PENINSULA. SO FAR...HIGHEST AMOUNTS
WITH THE SYSTEM HAVE BEEN LESS THAN AN INCH. SE BLYR WINDS OFF LK
MICHIGAN WILL CONTRIBUTE TO INCREASING LAKE ENHANCED SNOW FOR DELTA
COUNTY AND SCHOOLCRAFT COUNTY THIS AFTN. NOT ALL THAT COLD AT H85 BUT
INVERSION TOP TEMPS ARE SLIGHTLY COLDER...AROUND -8C...LEADING TO
DELTA T/S AROUND 13C. SCNTRL UPR MI IS ALSO WHERE RUC INDICATES
PERIOD OF H85 THETA-E ADVECTION TO ENHANCE THE SNOW. OPTED TO INCLUDE
DELTA COUNTY IN SNOW ADVY FOR AFTN. TOTAL SNOW AMOUNTS WILL BE A
STRETCH TO REACH 4 INCHES FOR THE AFTN...BUT TOTALS IN THE 2 TO 4
INCH RANGE WITH LOWER VSBY...DOWN TO 1/2SM IN HEAVIER SNOW...SEEMS TO
JUSTIFY PUTTING DELTA INTO THE ADVY. EXPECT HEAVIER SNOW TO CEASE
BY LATE AFTN OR EARLY EVENING AS BETTER THETA-E ADVECTION DIMINISHES
TO THE EAST AS MAIN SHORTWAVE MOVES OUT OF THE AREA.
OTHER SPOT TO WATCH WILL BE KEWEENAW AS SIMILAR SETUP IS PRESENT.
SHEAR IN LOWEST 2KFT IS MORE NOTED WITH ESE WINDS AT SFC AND MORE
SRLY WINDS TOWARD 925MB PER MQT VWP. HIGHER TERRAIN OF KEWEENAW
COUNTY IS ORIENTED MORE WEST-TO-EAST SO WITH THE SOUTHERLY WINDS IN
LOW-LEVELS THERE IS MORE OF AN UPSLOPE COMPONENT THERE COMPARED TO
HOUGHTON COUNTY. COUNTY SHERIFF REPORTS A COUPLE INCHES THUS FAR OVR
HIGHER TERRAIN. SINCE HEAVIER SNOW MAY LAST A FEW HOURS LONGER BASED
ON STRONGER H85 THETA-E ADVECTION...WILL PUT ADVY UP FOR KEWEENAW
COUNTY FOR THE AFTN. &&
PREV DISCUSSION...ISSUED AT 631 AM EST THU DEC 29 2011...
.SYNOPSIS...
WV IMAGERY AND RUC ANALYSIS INDICATED A STRONG WRLY MID/UPPER LEVEL
FLOW INTO THE PAC NW AND WNW FLOW DOWNSTREAM FROM THE SRN CANADA AND
NRN PLAINS INTO THE GREAT LAKES. ONE SHEARED SHORTWAVE TROUGH WAS
LOCATED NORTH OF LAKE SUPERIOR AND ANOTHER WAS MOVING THROUGH SW MN.
AT THE SFC...A 997 MB LOW WAS LOCATED OVER SRN MN RESULTING IN S TO
SE WINDS ACROSS UPPER MICHIGAN. AN AREA OF SNOW FROM NE MN INTO WRN
LAKE SUPERIOR NW WI WITH VSBYS INTO THE 1-3SM RANGE WAS SUPPORTED BY
285K-290K ASCENT AHEAD OF A 850-700 MB TROUGH. ANY LAKE EFFECT/ENHANCED
SNOW OFF OF LAKE MICHIGAN WITH THE SRLY FLOW HAS BEEN MINIMAL WITH
ONLY A DUSTING AT MOST.
&&
.DISCUSSION...
TODAY AND TONIGHT...EXPECT THE AREA OF SNOW TO PROGRESS ACROSS UPPER
MICHIGAN TODAY. MODELS CONSENSUS QPF OF AROUND A TENTH OF AN INCH
WITH SNOW/WATER RATIO VALUES NEAR 15/1 WOULD RESULT IN SNOWFALL
AMOUNTS OF AN INCH OR TWO WHICH IS REASONABLE GIVEN 2G-3G/KG
MOISTURE AVBL NEAR 700MB DURING A 6 HOUR PERIOD OF STRONGER LIFT.
UNCERTAINTY REMAINS WITH REGARD TO LAKE ENHANCED SNOW POTENTIAL INTO
THE SE CWA. THE HIGHER RES MODELS HAVE BEEN OVERDOING PCPN WITH
BANDS OFF OF LAKE MICHIGAN SO FAR. HOWEVER...AS THE DEEPER MOISTURE
ARRIVES...EXPECT THAT THE LAKE CONTRIBUTION MAY ADD AN ADDITIONAL
1-2 INCHES TO SNOWFALL AMOUNTS. SINCE THE WINDS WERE BACKING MORE
SERLY AHEAD OF THE LOW...THE BEST LOW LEVEL CONV AND OVER WATER
TRAJECTORIES HAVE SHIFTED TO THE WEST. SO...HAVE CANCELLED THE ADVY
FOR LUCE COUNTY AND CONTINUED MENTION OF 2 TO 4 INCHES OF SNOW IN
THE ADVY FOR SCHOOLCRAFT COUNTY TODAY. MODELS SUGGEST THAT THE
DEEPER MOISTURE WILL QUICKLY DEPART THIS AFTERNOON OVER THE WEST.
HOWEVER...LACK OF LOW LEVEL LIFT OR FOCUSING MECHANISM SHOULD
MINIMIZE POTENTIAL FOR -FZDZ. SOME LIGHT SNOW WILL LINGER OVER THE
ERN CWA TONIGHT AS THE SFC-850 MB TROUGH SLOWLY PIVOTS TO THE NORTHEAST.
FRIDAY...MODELS WERE IN AGREEMENT THAT THE PCPN ASSOCIATED WITH A
SHORTWAVE MOVING FROM THE PAC THROUGH THE NRN PLAINS INTO THE MS
VALLEY AND SRN GREAT LAKES IS EXPECTED TO REMAIN SOUTH OF UPPER MI.
SOME ISOLATED LIGHT SNOW SHOWERS MAY BE POSSIBLE NEAR AN INVERTED
TROUGH AXIS INTO THE NRN CWA. AGAIN...-FZDZ MAY ALSO BE POSSIBLE BUT
PROBABILITIES REMAIN LOW.
SAT INTO SUN...THE NEXT MID LEVEL TROUGH IN THE PROGRESSIVE PATTERN
WILL MOVE INTO THE REGION BY LATE SAT. WAA AHEAD OF THE MID LEVEL
AND SFC TROUGH MAY BRING SOME LIGHT PCPN INTO THE WRN CWA. THE
MORE CONSISTENT ECMWF WAS PREFERRED FOR DETAILS WITH THE SYSTEM AS
THE GFS AND NAM HAVE AT TIMES SHOWED A STRONGER SHORTWAVE SWEEPING
THROUGH THE REGION THAT WOULD GENERATE SUBSTANTIAL PCPN AND BRING
MUCH GREATER DEEPENING OF THE SFC LOW. FALLING TEMPS AND BLUSTERY WNW
WINDS ARE EXPECTED BY SUN AFTERNOON BEHIND A STRONG COLD FRONT.
SUN NIGHT INTO TUE...AS THE PATTERN BRIEFLY AMPLIFIES...MUCH
COLDER AIR WILL POUR INTO THE WRN LAKES ON NW TO N WINDS DROPPING
850 MB TEMPS TO AROUND -20C. SUBTLE MODEL DIFFERENCES REMAIN WITH
THE PREVAILING WIND DIRECTION AS THE GFS REMAINS MORE TO THE NW
COMPARED TO THE NRLY DIRECTION DEPICTED BY THE ECMWF/GEM. SIGNIFICANT
LES REMAINS POSSIBLE WITH INTENSITY DROPPING OFF MON AS DEEPER
MOISTURE DEPARTS.
&&
.AVIATION /FOR THE 12Z TAF ISSUANCE/...
A LOW PRESSURE SYSTEM MOVING S OF THE AREA TODAY WILL BRING -SN TO
ALL TAF SITES...RESULTING IN IFR CONDITIONS. LIFR CONDITIONS ARE
POSSIBLE AS WELL...ESPECIALLY AT KCMX...DURING PERIOD OF HEAVIEST
SNOW. IMPROVEMENT EXPECTED W TO E LATE MORNING/AFTN AS MAIN AREA OF
-SN EXITS. HOWEVER...IT MAY BE DIFFICULT TO GET RID OF THE LOWER
CIGS GIVEN LIGHT LOW-LEVEL WINDS AND THUS WEAK ADVECTION OF ANY
DRIER AIR AT THE LOW-LEVELS. SO...CIGS MAY REMAIN IFR OR ONLY RISE
SLIGHTLY TO LOW MVFR IN THE AFTN. IWD IS THE MOST LIKELY TO SEE
SIGNIFICANT IMPROVEMENT.
&&
.MARINE /FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE/...
A LOW PRESSURE SYSTEM OVER MN WILL MOVE EAST TODAY. ALTHOUGH WINDS
SHOULD STAY BELOW GALE FORCE...THEY WILL BECOME RATHER GUSTY OUT OF
THE SOUTHEAST WITH PERHAPS A GUST OR TWO CLOSE TO GALE FORCE. AFTER
ANOTHER LOW MOVES ACROSS THE LOWER LAKES ON FRIDAY...A WEAK RIDGE
BUILDS ACROSS LAKE SUPERIOR INTO SATURDAY BEFORE A STRONG LOW
DEVELOPS OVER THE PLAINS AND MOVES NORTH OF LAKE SUPERIOR FOR NEW
YEARS DAY. HIGH END NORTH-NORTHWEST GALES ARE POSSIBLE WITH THIS
SYSTEM INTO MONDAY.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
WINTER WEATHER ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ013-
014-085.
WINTER WEATHER ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ001.
LAKE SUPERIOR...
NONE.
LAKE MICHIGAN...
NONE.
&&
$$
UPDATE...JLA
SYNOPSIS...JLB
DISCUSSION...JLB
AVIATION...TITUS
MARINE...TITUS
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
326 PM CST THU DEC 29 2011
.UPDATE...
.AVIATION...
MID AND HIGH LEVEL CLOUDS WILL CONTINUE ACROSS WESTERN
AND NORTH CENTRAL NEBRASKA THIS AFTERNOON...WITH SKIES CLEARING
TONIGHT. CEILINGS MAY GET AS LOW AS 5000 FT AGL...ALONG WITH SCT
RAIN SHOWERS AND A FEW THUNDERSTORMS LATE THIS AFTERNOON AND EARLY
THIS EVENING. OVERALL VFR EXPECTED TO PREVAIL...WITH GUSTY WEST
WINDS TO 40 KTS WEST OF HIGHWAY 183 FROM LATE AFTERNOON THROUGH THE
EVENING. LOCAL GUSTS TO 50 KTS ARE POSSIBLE INVOF SHOWERS/STORMS.
&&
.PREV DISCUSSION... /ISSUED 321 PM CST THU DEC 29 2011/
DISCUSSION...
SHORT TERM...
WIND ADVISORY CONDITIONS ARE SPREADING THROUGH ALL OF THE WRN NEB
PANHANDLE THIS AFTERNOON. THERE IS THE POTENTIAL FOR STRONG WINDS
TO SPREAD THROUGH ALL OF THE PANHANDLE UNTIL 23Z. THEREAFTER THE
LOSS OF DAYTIME HEATING SHOULD CAUSE A DROP IN GUSTS. 30 MPH
SUSTAINED CONDITIONS MIGHT CONTINUE THIS EVENING AS LOW PRESSURE
TRACKS THROUGH THE MISSOURI BASIN. THE RUC SHOWS A PRONOUNCED TROP
FOLD ON THE PV15 SURFACE WHICH SHOULD MOVE THRU THE FCST AREA THIS
EVENING. THUS THE WIND ADZY WILL CONTINUE ACROSS GARDEN AND DEUEL
COUNTIES WITH A POSSIBLE NORTH AND EAST EXPANSION AS CONDITIONS
WARRANT. SCATTERED SHOWERS ISOLATED THUNDERSTORMS ARE EXPECTED TO CONTINUE
TRACKING THRU NRN NEB THIS EVENING.
THE STRONG WEST WINDS ARE BEING USHERED IN AHEAD OF A PACIFIC COLD
FRONT WORKING THRU NERN WY. THE FRONT SHOULD COOL TEMPS OFF
SOMEWHAT FOR FRIDAY WITH HIGHS ABOUT 10F COOLER THAN TODAY.
ANOTHER STRONG COLD FRONT IS EXPECTED TO MOVE THROUGH SATURDAY
MORNING...EARLY AFTERNOON. THIS FRONT IN COMBINATION WITH
DEEPENING LOW PRESSURE ACROSS THE UPPER MIDWEST AND VERY STRONG
PACIFIC HIGH PRESSURE SHOULD PRODUCE WIND ADVISORY CONDITIONS
ACROSS MOST AND POSSIBLY ALL OF THE FCST AREA. A BLEND OF MODEL
DATA AND GUIDANCE WAS USED FOR THE FCST WHICH PRODUCED HIGH END
WIND ADVISORY CONDITIONS ACROSS SWRN NEB.
AMPLE MOISTURE WILL BE PRESENT ALONG AND BEHIND THE FRONT SATURDAY
FOR SCATTERED RAIN AND SNOW SHOWERS...MAINLY ACROSS THE NORTH.
ANOTHER STRONG TROP FOLD WILL SWEEP THE FCST AREA IN CONCERT WITH
THE FRONTAL PASSAGE. THE GFS WAS OVERPOWERING WITH THE WIND
STRENGTH AND COLD AIR PRODUCING ALL SNOW WHILE THE NAM SHOWED A
MIX WITH WEAKER WINDS. THE WARMER NAM WAS PREFERRED.
PACIFIC HIGH PRESSURE WILL BUILD ACROSS THE FCST AREA SUNDAY
PRODUCING HIGHS IN THE UPPER 30S TO AROUND 40 WITH NEARLY CLEAR SKIES.
LONG TERM...
A RIDGE OF HIGH PRESSURE ALOFT WILL BE AMPLIFYING MONDAY ACROSS THE
ROCKIES...WHILE A TROUGH OF LOW PRESSURE CONTINUES IT/S EASTWARD
PROGRESSION INTO THE NORTHEAST STATES. OUR AREA WILL BE IN BETWEEN
THESE TWO FEATURES...WITH A BROAD NORTHWEST FLOW ALOFT. 850 MB
TEMPERATURES WILL BEGIN TO RECOVER MONDAY...AND CONTINUE TO WARM
THOUGH THURSDAY. IN FACT BY THURSDAY MODELS ARE SUGGESTING +15C OVER
THE AREA...WHICH WOULD PUT HIGH TEMPERATURES INTO POSSIBLE RECORD
TERRITORY. SO AFTER A COOL START MONDAY...HIGHS MID 30S TO MID
40S...TUESDAY THROUGH THURSDAY LOOKING VERY MILD. COULD BE PUSHING
60 DEGREES OR WARMER AGAIN BY THURSDAY.
AVIATION...
MID AND HIGH LEVEL CLOUDS WILL CONTINUE ACROSS WESTERN
AND NORTH CENTRAL NEBRASKA THIS AFTERNOON...WITH SKIES CLEARING
TONIGHT. CEILINGS MAY GET AS LOW AS 5000 FT AGL...ALONG WITH A FEW
RAIN SHOWERS...ACROSS NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AND
EARLY THIS EVENING. VFR EXPECTED TO PREVAIL...WITH GUSTY WEST
WINDS TO 30 KTS WEST OF HIGHWAY 83 FROM LATE AFTERNOON THROUGH THE
EVENING.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY UNTIL 11 PM MST THIS EVENING FOR NEZ022-056.
&&
$$
SHORT TERM...CDC
AVIATION/EXTENDED...TAYLOR
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
321 PM CST THU DEC 29 2011
.DISCUSSION...
.SHORT TERM...
WIND ADVISORY CONDITIONS ARE SPREADING THROUGH ALL OF THE WRN NEB
PANHANDLE THIS AFTERNOON. THERE IS THE POTENTIAL FOR STRONG WINDS
TO SPREAD THROUGH ALL OF THE PANHANDLE UNTIL 23Z. THEREAFTER THE
LOSS OF DAYTIME HEATING SHOULD CAUSE A DROP IN GUSTS. 30 MPH
SUSTAINED CONDITIONS MIGHT CONTINUE THIS EVENING AS LOW PRESSURE
TRACKS THROUGH THE MISSOURI BASIN. THE RUC SHOWS A PRONOUNCED TROP
FOLD ON THE PV15 SURFACE WHICH SHOULD MOVE THRU THE FCST AREA THIS
EVENING. THUS THE WIND ADZY WILL CONTINUE ACROSS GARDEN AND DEUEL
COUNTIES WITH A POSSIBLE NORTH AND EAST EXPANSION AS CONDITIONS
WARRANT. SCATTERED SHOWERS ISOLATED THUNDERSTORMS ARE EXPECTED TO CONTINUE
TRACKING THRU NRN NEB THIS EVENING.
THE STRONG WEST WINDS ARE BEING USHERED IN AHEAD OF A PACIFIC COLD
FRONT WORKING THRU NERN WY. THE FRONT SHOULD COOL TEMPS OFF
SOMEWHAT FOR FRIDAY WITH HIGHS ABOUT 10F COOLER THAN TODAY.
ANOTHER STRONG COLD FRONT IS EXPECTED TO MOVE THROUGH SATURDAY
MORNING...EARLY AFTERNOON. THIS FRONT IN COMBINATION WITH
DEEPENING LOW PRESSURE ACROSS THE UPPER MIDWEST AND VERY STRONG
PACIFIC HIGH PRESSURE SHOULD PRODUCE WIND ADVISORY CONDITIONS
ACROSS MOST AND POSSIBLY ALL OF THE FCST AREA. A BLEND OF MODEL
DATA AND GUIDANCE WAS USED FOR THE FCST WHICH PRODUCED HIGH END
WIND ADVISORY CONDITIONS ACROSS SWRN NEB.
AMPLE MOISTURE WILL BE PRESENT ALONG AND BEHIND THE FRONT SATURDAY
FOR SCATTERED RAIN AND SNOW SHOWERS...MAINLY ACROSS THE NORTH.
ANOTHER STRONG TROP FOLD WILL SWEEP THE FCST AREA IN CONCERT WITH
THE FRONTAL PASSAGE. THE GFS WAS OVERPOWERING WITH THE WIND
STRENGTH AND COLD AIR PRODUCING ALL SNOW WHILE THE NAM SHOWED A
MIX WITH WEAKER WINDS. THE WARMER NAM WAS PREFERRED.
PACIFIC HIGH PRESSURE WILL BUILD ACROSS THE FCST AREA SUNDAY
PRODUCING HIGHS IN THE UPPER 30S TO AROUND 40 WITH NEARLY CLEAR SKIES.
.LONG TERM...
A RIDGE OF HIGH PRESSURE ALOFT WILL BE AMPLIFYING MONDAY ACROSS THE
ROCKIES...WHILE A TROUGH OF LOW PRESSURE CONTINUES IT/S EASTWARD
PROGRESSION INTO THE NORTHEAST STATES. OUR AREA WILL BE IN BETWEEN
THESE TWO FEATURES...WITH A BROAD NORTHWEST FLOW ALOFT. 850 MB
TEMPERATURES WILL BEGIN TO RECOVER MONDAY...AND CONTINUE TO WARM
THOUGH THURSDAY. IN FACT BY THURSDAY MODELS ARE SUGGESTING +15C OVER
THE AREA...WHICH WOULD PUT HIGH TEMPERATURES INTO POSSIBLE RECORD
TERRITORY. SO AFTER A COOL START MONDAY...HIGHS MID 30S TO MID
40S...TUESDAY THROUGH THURSDAY LOOKING VERY MILD. COULD BE PUSHING
60 DEGREES OR WARMER AGAIN BY THURSDAY.
&&
.AVIATION...
MID AND HIGH LEVEL CLOUDS WILL CONTINUE ACROSS WESTERN
AND NORTH CENTRAL NEBRASKA THIS AFTERNOON...WITH SKIES CLEARING
TONIGHT. CEILINGS MAY GET AS LOW AS 5000 FT AGL...ALONG WITH A FEW
RAIN SHOWERS...ACROSS NORTH CENTRAL NEBRASKA LATE THIS AFTERNOON AND
EARLY THIS EVENING. VFR EXPECTED TO PREVAIL...WITH GUSTY WEST
WINDS TO 30 KTS WEST OF HIGHWAY 83 FROM LATE AFTERNOON THROUGH THE
EVENING.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY UNTIL 11 PM MST THIS
EVENING FOR NEZ022-056.
&&
$$
SHORT TERM...CDC
AVIATION/EXTENDED...TAYLOR