Forecast Discussions mentioning any of
"HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 01/12/13
FORECAST DISCREPANCIES STILL SHOW UP FOR SATURDAY WITH NAM AND GFS
MODELS BRINGING A WET INSIDE SLIDER OVER THE BAY AREA SATURDAY
AFTERNOON BRINGING A ROUND OF COLD RAIN SHOWERS. THE ECMWF IS DRY
AND REMAINS THE MODEL OF CHOICE...SO FORECAST REMAINS DRY. GFS AND
PREVIOUS NAM RUNS QUICKLY BRING ANOTHER SYSTEM BY 12Z SUNDAY THAT
THE ECMWF DOESN`T SHOW. WILL NEED TO MONITOR TRENDS TO COVER
WEEKEND FORECAST PROPERLY ONCE WE GET THROUGH THIS INITIAL SHOT OF
COLD AND UNSETTLED AIR. EXPECTED LONGWAVE PATTERN SUPPORTS THE
DRIER ECMWF SOLUTION. HIGHER CONFIDENCE FOR DRYING AND WARMING
TREND SUNDAY INTO EARLY NEXT WEEK AS HIGH PRESSURE BUILDS.
&&
.AVIATION...AS OF 9:45 AM PST THURSDAY...A TROUGH OF LOW PRESSURE
CONTINUES TO PUSH SOUTH ALONG THE COAST THIS MORNING. THE COOL AIR
ALOFT...ASSOCIATED WITH THIS TROUGH...IS GENERATING INSTABILITY
RESULTING IN DENSE CUMULUS OVER THE HILLS AND SCATTERED TO BROKEN
CIGS OVER THE TERMINALS. WITH HEATING OF THE DAYS A FEW OF THESE
CUMULUS MAY BECOME CUMULONIMBUS RESULTING IN AN ISOLATED
AFTERNOON SHOWER.
VICINITY OF KSFO...VFR CONDITIONS ARE EXPECTED TODAY WITH A SHOWER
IN THE VICINITY OF THE TERMINAL. WINDS WILL INCREASE OUT OF THE
WEST REACHING 18 KT WITH GUSTS TO 25 KT BY 2300Z.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...VFR IS EXPECTED TO PREVAIL TODAY
WITH A SHOWER IN THE VICINITY OF THE TERMINAL. WINDS WILL INCREASE
OUT OF THE WEST 15 KT GUSTING TO 21 KT BY 2200Z.
&&
.MARINE...AS OF 3:45 AM PST THURSDAY...ISOLATED THUNDERSTORMS AND
AREAS OF SMALL HAIL ARE FORECAST FOR TODAY AS AN UNSTABLE AIRMASS
REMAINS OVER THE AREA. SOME THUNDERSTORMS COULD HAVE BRIEF
ROTATION.
A KING TIDE WILL COINCIDE WITH LARGE NORTHERLY SWELLS ENTERING THE
WATERS OVER THE NEXT FEW DAYS. A KING TIDE WILL BE PRESENT TODAY
AND CONTINUE THROUGH FRIDAY...WITH LOCALIZED FLOODING POSSIBLE
ACROSS LOW LYING AREAS NEAR THE COASTLINE. THESE HIGH TIDES WILL
BE PRESENT EACH MORNING BEGINNING TODAY AND CONTINUING INTO
FRIDAY. THE LOW TIDE WILL BE PRESENT EACH AFTERNOON/EARLY EVENING.
FOR DETAILED INFORMATION ON THE KING TIDE FOR A SPECIFIC AREA
ALONG THE COAST...PLEASE SEE WWW.CALIFORNIAKINGTIDES.ORG.
IN ADDITION...NORTHERLY SWELLS WILL CONTINUE TO BUILD TODAY. COMBINED
SEAS MAINLY BETWEEN 13 AND 16 FEET WITH A PERIOD OF 13 SECONDS
WILL BE PRESENT THURSDAY AFTERNOON INTO FRIDAY MORNING. THESE
SWELLS IN COMBINATION WITH THE KING TIDE MAY CAUSE ADDITION MINOR
COASTAL FLOODING. SWELLS WILL BEGIN TO SLOWLY SUBSIDE FRIDAY
AFTERNOON INTO THE WEEKEND.
PLEASE CONTINUE TO MONITOR THE FORECAST FOR THE LATEST INFORMATION
ON BOTH KING TIDE AND THE LARGE NORTHERLY SWELLS.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
.TDAY...WINTER WEATHER ADVISORY...SANTA CRUZ MTNS TIL 1 PM
WINTER WEATHER ADVISORY...SANTA LUCIA MTNS TIL 4 PM
SCA...PT ARENA TO PT REYES 0-10 NM SCA...PT REYES TO PIGEON PT 0-10 NM
SCA...PIGEON PT TO PT PINOS 0-10 NM
SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM
SCA...PT ARENA TO PIGEON PT 10-60 NM
SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM
SCA...ROUGH BAR ADVISORY FOR SF BAR
&&
$$
PUBLIC FORECAST: STROBIN/RWW
AVIATION/MARINE: LARRY
VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO
FOLLOW US ON FACEBOOK, TWITTER, AND YOUTUBE AT:
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV
WWW.TWITTER.COM/NWSBAYAREA
WWW.YOUTUBE.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1032 PM MST WED JAN 9 2013
.AVIATION...
VFR CONDITIONS ARE EXPECTED AT KCOS AND KPUB THROUGH 06Z SATURDAY.
WINDS WILL REMAIN LIGHT AND VARIABLE OVERNIGHT AND THROUGH MUCH OF
THURSDAY MORNING.
KALS WILL LIKELY SEE SCT001 WITH ISOLATED BKN001 SKIES EARLY
THURSDAY MORNING WITH ONLY LOCAL IFR/LIFR CIGS POSSIBLE FROM 09Z
TO 15Z. -PJC
&&
.PREV DISCUSSION... /ISSUED 958 PM MST WED JAN 9 2013/
UPDATE...
UPDATED THE GRIDS TO LOWER TEMPERATURES IN THE SAN LUIS VALLEY AS
SKIES WILL REMAIN CLEAR FOR THE NEXT FEW HOURS. CLEAR SKIES AND
SNOW COVER WILL ALLOW TEMPERATURES TO FALL TO NEAR -20F BEFORE
HIGH CLOUDS MOVE OVERHEAD EARLY FRIDAY MORNING. -PJC
PREV DISCUSSION... /ISSUED 247 PM MST WED JAN 9 2013/
SHORT TERM...
(TONIGHT AND TOMORROW)
.MAIN SHORT TERM CONCERN IS THE CHANCE OF RAIN AND FREEZING RAIN
ACROSS THE FAR SE PLAINS...
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING WEAK
MAINLY WESTERLY FLOW ALOFT ACROSS THE AREA WITH A LARGE UPPER LOW
STILL SPINNING ACROSS NORTHEASTERN MEXICO JUST SOUTH AND WEST OF DEL
RIO TEXAS AT THIS TIME. WATER VAPOR IMAGERY INDICATING MID AND UPPER
LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM SPREADING NORTH INTO
EASTERN NEW MEXICO AND WESTERN TEXAS...WITH MID AND UPPER LEVEL
MOISTURE ALSO SPREADING INTO THE GREAT BASIN REGION AHEAD OF A
DEVELOPING STORM SYSTEM MOVING ONSHORE ACROSS THE PAC NW COAST AT
THIS TIME. WITH THE LIGHT WINDS...TEMPERATURES HAVE STRUGGLED TO
WARM WITH READINGS IN THE MID 40S TO LOWER 50S ACROSS THE LOWER
ELEVATIONS AND 20S AND 30S ACROSS THE HIGHER ELEVATIONS. TEMPS IN
THE SAN LUIS VALLEY CONTINUE TO LAG BEHIND WITH READINGS MAINLY IN
THE TEENS AND 20S...WITH THE COLDEST READINGS IN THE CENTRAL
PORTIONS OF THE VALLEY.
TONIGHT...MODELS STILL DIFFER ON LOCATION OF EJECTING LOW WITH THE
12Z GFS AND EC THE FURTHEST NORTH AND WEST WITH THE LOW NORTH OF
ABILENE TEXAS AT 12Z THU...WHERE AS THE HIGHER RES NAM AND RAP KEEP
THE LOW FURTHER SOUTH AND EAST. THE FURTHER NORTH SOLUTIONS OF THE
EC AND ESPECIALLY THE GFS ARE INDICATING STRONGER MID LEVEL WAA
ACROSS THE WESTERN TX AND OKLAHOMA PANHANDLE THROUGH EASTERN
COLORADO AND WESTERN KANSAS AND ARE PRINTING OUT MORE QPF ACROSS THE
FAR SOUTHEAST PLAINS AS A RESULT. THE HIGHER RES MODELS KEEP THE
BEST LIFT AND WAA FURTHER EAST ACROSS WESTERN AND CENTRAL KANSAS
WHICH IS ALSO SUPPORTED BY LOCAL HIGH RES WRF MODEL. WITH THAT
SAID...HAVE KEPT CURRENT FORECAST TRENDED TOWARDS THE HIGHER RES
MODELS KEEPING SILENT POPS THROUGH 06Z WITH CHANCE POPS ACROSS
EASTERN PORTIONS OF BACA AND PROWERS COUNTIES AND SLIGHT POPS
FURTHER NORTH AND WEST INTO KIOWA AND WESTERN PROWERS AND BACA
COUNTIES THEREAFTER. SOUNDINGS INDICATING MAINLY LIGHT RAIN ACROSS
BACA COUNTY THOUGH DO INDICATE A BRIEF PERIOD OF LIGHT FREEZING RAIN
POSSIBLE ACROSS PROWERS AND KIOWA COUNTIES...WITH LATER SHIFTS
NEEDING TO MONITOR LATEST MODELS AND TRENDS. ELSEWHERE...WEAK
WESTERLY FLOW THIS EVENING BECOMES MORE SOUTHWEST AND SLOWLY
INCREASES OVERNIGHT AS EASTERN PACIFIC SYSTEM CONTINUES TO MOVE
ONSHORE ACROSS THE WEST COAST. MAINLY CLEAR SKIES WEST OF THE PLAINS
WILL HELP COOL TEMPS ONCE AGAIN IN THE SAN LUIS VALLEY...WITH THE
WARMEST READINGS EXPECTED ACROSS THE HIGHER TERRAIN ALONG AND WEST
OF THE I-25 CORRIDOR WHERE LEE TROUGHING DEVELOPS OVERNIGHT.
TOMORROW...SOUTHWEST FLOW ALOFT CONTINUES TO INCREASE THROUGH THE
DAY AS THE WEST COAST SYSTEM TRANSLATES INTO THE GREAT BASIN.
MOISTURE PROGGED TO INCREASE FROM WEST TO EAST AND WITH INCREASING
OROGRAPHICS COULD SEE SOME LIGHT SNOW DEVELOPING ACROSS THE HIGHER
TERRAIN OF THE SOUTHWEST MTS BY THE LATE AFTERNOON. LEE TROUGHING
STRENGTHENS ACROSS THE I-25 CORRIDOR WITH BREEZY SOUTH TO SOUTHWEST
WINDS DEVELOPING ACROSS THE PLAINS BOOSTING TEMPS INTO THE LOWER TO
MID 50S. INCREASING CLOUDS AND SLIGHT COOLING ALOFT WILL LEAD TO
SLIGHTLY COOLER TEMPS ACROSS THE HIGHER TERRAIN AND HIGH VALLEYS.
LONG TERM...
(THURSDAY NIGHT THROUGH WEDNESDAY)
.HIGH IMPACT WEATHER TO AFFECT PORTIONS OF SOUTH CENTRAL AND
SOUTHEAST COLORADO THURSDAY NIGHT THROUGH FRIDAY...WITH A TURN
TOWARDS MUCH COLDER TEMPERATURES THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...
A CLOSED UPPER LOW CARVES OUT ACROSS THE GREAT BASIN THURSDAY NIGHT
SENDING STRONG SOUTHWEST FLOW...WITH 110-120+ KT UPPER JET ACROSS
COLORADO BY 12Z FRIDAY. MOISTURE DEEPENS ALONG THE CONTINENTAL
DIVIDE THURSDAY EVENING...WITH SNOW RAMPING UP ALONG THE
OROGRAPHICALLY FAVORED EASTERN SAN JUAN MOUNTAINS. COMBINED WITH
MTN TOP WINDS OF 50-60 KTS...HAZARDOUS CONDITIONS WILL BE POSSIBLE
DUE TO WHITE OUT CONDITIONS IN BLOWING SNOW ACROSS ZONE 68...WHICH
INCLUDES THE WOLF CREEK PASS. HAVE UPGRADED THE WINTER STORM WATCH
TO A BLIZZARD WATCH FOR THIS ZONE. SNOW SHOULD SPREAD NORTH AND
EASTWARD AFTER MIDNIGHT THROUGH THE MORNING HOURS...WITH THE
HEAVIEST SNOW EXPECTED TO FALL BEFORE 18Z WHEN BEST FORCING MOVES
THROUGH. WINDS THEN SHIFT MORE FROM THE WEST TO NORTHWEST FRIDAY
AFTERNOON...WITH THE FOCUS FOR SNOW SHIFTING INTO THE EASTERN
SAWATCH AND WESTERN MOSQUITO RANGES DURING THE AFTERNOON. OVERALL
SNOWFALL AMOUNTS FOR THE BRUNT OF THE EVENT...THURS
NIGHT/FRI...SHOULD RANGE FROM 8 TO 17 INCHES ACROSS THE EASTERN SAN
JUAN MOUNTAINS...WITH AROUND 5 TO 10 INCHES WITH LOCALLY UP TO A
FOOT FOR THE LA GARITAS...EASTERN SAWATCH AND WESTERN MOSQUITO
RANGES. THINK THAT THESE LATTER AREAS WILL EVENTUALLY NEED A WINTER
WEATHER ADVISORY...BUT SINCE SNOW AMOUNTS HAVE BEEN CONSISTENTLY
COMING UP SHORT OF WARNING NUMBERS (12" OR MORE IN GREATER THAN 12
HOURS)...NO WATCHES WILL BE ISSUED AT THIS POINT.
AS THE UPPER JET TRANSLATES ACROSS THE AREA THURSDAY NIGHT THROUGH
FRIDAY...A BORA COLD FRONT WILL MOVE FROM WEST TO EAST ACROSS THE
REGION. HIGHER PEAKS SHOULD START BLOWING FIRST AS MTN TOP WINDS
INCREASE TO AROUND 50-60 KTS. THERE IS QUITE A BIT OF FORWARD SHEAR
WITH THIS SYSTEM...SO THIS DOESN`T APPEAR TO BE A MTN WAVE EVENT.
HOWEVER AS THE NORTH-SOUTH ORIENTED COLD FRONT CROSSES THE
MOUNTAINS...IT COULD BRING A PERIOD OF STRONG GUSTY WINDS INTO THE
ADJACENT LOWER ELEVATIONS OF THE SAN LUIS VALLEY AND THE I-25
CORRIDOR EARLY FRIDAY MORNING AS COLD DENSE AIR SPILLS OVER THE
MOUNTAINS. SFC PRESSURE GRADIENT IS IMPRESSIVE FRIDAY MORNING AS
THE SURFACE LOW DEEPENS ACROSS NORTHEAST COLORADO WHICH SHOULD ALSO
AID IN MIXING STRONG WINDS ALOFT TO THE SURFACE ACROSS THE REMAINDER
OF THE SOUTHEAST PLAINS. ALREADY HAVE A HIGH WIND WATCH OUT AND PLAN TO
MAINTAIN IT. DID BUMP UP THE START TIME OF THE HIGH WIND WATCH TO
MIDNIGHT ACROSS THE SOUTHEAST MTS AS WINDS ALOFT WILL BE INCREASING
AFTER MIDNIGHT...THOUGH THINK STRONGER GUSTS WILL STAY ACROSS THE
HIGHER ELEVATIONS UNTIL FRIDAY MORNING WHEN THE FRONT MOVES THROUGH. WINDS
MAY COME UP JUST SHY OF HIGH WIND CRITERIA ACROSS CENTER PORTIONS OF
THE SAN LUIS VALLEY...BUT VALLEY EDGES...PARTICULARLY ON THE WESTERN
SIDE COULD SEE A PERIOD OF HIGH WINDS FRIDAY MORNING.
BROAD TROFFING REMAINS ACROSS THE GREAT BASIN AND ROCKIES REGION
THROUGH EARLY NEXT WEEK AS ENERGY CONTINUES TO DROP SOUTHWARD OUT OF
CANADA. THIS WILL KEEP VERY COLD AND GENERALLY UNSETTLED CONDITIONS
ACROSS THE REGION THROUGH EARLY NEXT WEEK. TEMPERATURES WILL DROP
OFF CONSIDERABLY ACROSS THE PLAINS...WITH HIGHS STRUGGLING TO REACH
THE 30S BY THE MIDDLE OF NEXT WEEK. MEANWHILE...THE MOUNTAINS AND
VALLEYS WILL BE DROPPING INTO THE NEGATIVE DIGITS AT NIGHT...WITH
KALS LIKELY TO HIT -30 OR BELOW AS A NEW BATCH OF COLD AIR GETS
ENTRENCHED IN THE VALLEY. NEXT WAVE OF ENERGY LIFTS OUT OF THE MEAN
TROF ACROSS SOUTHERN PORTIONS OF THE AREA SAT NIGHT...AND WITH
SHALLOW UPSLOPE AND COLD AIR...WE COULD SEE SOME ADDITIONAL LIGHT
SNOW ACROSS THE MOUNTAINS AND ADJACENT PLAINS...BUT EACH SUCCESSIVE
MODEL RUN HAS BEEN DRIER...SO WILL LEAVE THE SILENT POPS ACROSS THE
PLAINS...WITH GENERALLY ISOLATED TO LOW END SCATTERED POPS ACROSS
THE MOUNTAINS. SAME THING HAPPENS FOR MONDAY NIGHT AS ANOTHER WAVE
OF ENERGY DROPPING INTO THE BASE OF THE TROF CLOSES OFF AN UPPER LOW
ACROSS THE DESSERT SOUTHWEST AND LEADING SHORTWAVE ENERGY EJECTS TO
THE NORTHEAST ACROSS THE AREA. ONCE AGAIN...IF IT OCCURS...ANY
SNOWFALL ACCUMULATIONS APPEAR TO REMAIN LIGHT. GFS AND ECMWF ORPHAN THE
UPPER LOW ACROSS EXTREME SOUTHERN AZ/NRN OLD MEXICO THROUGH
WEDNESDAY WHICH IS TOO FAR SOUTH TO BRING ANY PRECIPITATION TO THE
AREA THROUGH WEDNESDAY. TEMPERATURES SHOULD SLOWLY MODERATE SOME
INTO THE MIDDLE OF NEXT WEEK. -KT
AVIATION...
VFR CONDITIONS TO PREVAIL AT KCOS AND KPUB THROUGH THE NEXT 24
HOURS WITH GENERALLY LIGHT WINDS THROUGH TONIGHT. BREEZY SOUTH TO
SOUTHWEST WINDS OF 15-20KTS ARE EXPECTED TO DEVELOP AFT 18Z THU.
KALS HAD STRONG RADIATIONAL COOLING AND SCT001 TO LOCALLY BKN001
ACROSS THE VALLEY FLOOR LATE LAST NIGHT AND EARLY THIS MORNING...BUT
VIS DID NOT DROP BELOW MFVR. WOULD THINK THE SAME FOR TONIGHT...AS
TEMPS DID NOT WARM AS MUCH AS EXPECTED. AT ANY RATE...VFR CONDITIONS
EXPECTED THROUGH 06Z THU...WITH LOCAL IFR AND LIFR CIGS THEN
POSSIBLE THROUGH 16Z. VFR AGAIN AFT 16Z THU. -MW
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM FRIDAY MORNING THROUGH FRIDAY AFTERNOON FOR
COZ069>071-083>089-093>099.
HIGH WIND WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY
AFTERNOON FOR COZ072>082.
BLIZZARD WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON
FOR COZ068.
&&
$$
81/10
AREA FORECAST DISCUSSION
NWS PUEBLO CO
958 PM MST WED JAN 9 2013
.UPDATE...
UPDATED THE GRIDS TO LOWER TEMPERATURES IN THE SAN LUIS VALLEY AS
SKIES WILL REMAIN CLEAR FOR THE NEXT FEW HOURS. CLEAR SKIES AND
SNOW COVER WILL ALLOW TEMPERATURES TO FALL TO NEAR -20F BEFORE
HIGH CLOUDS MOVE OVERHEAD EARLY FRIDAY MORNING. -PJC
&&
.PREV DISCUSSION... /ISSUED 247 PM MST WED JAN 9 2013/
SHORT TERM...
(TONIGHT AND TOMORROW)
..MAIN SHORT TERM CONCERN IS THE CHANCE OF RAIN AND FREEZING RAIN
ACROSS THE FAR SE PLAINS...
CURRENT WATER VAPOR IMAGERY AND UPPER AIR ANALYSIS INDICATING WEAK
MAINLY WESTERLY FLOW ALOFT ACROSS THE AREA WITH A LARGE UPPER LOW
STILL SPINNING ACROSS NORTHEASTERN MEXICO JUST SOUTH AND WEST OF DEL
RIO TEXAS AT THIS TIME. WATER VAPOR IMAGERY INDICATING MID AND UPPER
LEVEL MOISTURE ASSOCIATED WITH THIS SYSTEM SPREADING NORTH INTO
EASTERN NEW MEXICO AND WESTERN TEXAS...WITH MID AND UPPER LEVEL
MOISTURE ALSO SPREADING INTO THE GREAT BASIN REGION AHEAD OF A
DEVELOPING STORM SYSTEM MOVING ONSHORE ACROSS THE PAC NW COAST AT
THIS TIME. WITH THE LIGHT WINDS...TEMPERATURES HAVE STRUGGLED TO
WARM WITH READINGS IN THE MID 40S TO LOWER 50S ACROSS THE LOWER
ELEVATIONS AND 20S AND 30S ACROSS THE HIGHER ELEVATIONS. TEMPS IN
THE SAN LUIS VALLEY CONTINUE TO LAG BEHIND WITH READINGS MAINLY IN
THE TEENS AND 20S...WITH THE COLDEST READINGS IN THE CENTRAL
PORTIONS OF THE VALLEY.
TONIGHT...MODELS STILL DIFFER ON LOCATION OF EJECTING LOW WITH THE
12Z GFS AND EC THE FURTHEST NORTH AND WEST WITH THE LOW NORTH OF
ABILENE TEXAS AT 12Z THU...WHERE AS THE HIGHER RES NAM AND RAP KEEP
THE LOW FURTHER SOUTH AND EAST. THE FURTHER NORTH SOLUTIONS OF THE
EC AND ESPECIALLY THE GFS ARE INDICATING STRONGER MID LEVEL WAA
ACROSS THE WESTERN TX AND OKLAHOMA PANHANDLE THROUGH EASTERN
COLORADO AND WESTERN KANSAS AND ARE PRINTING OUT MORE QPF ACROSS THE
FAR SOUTHEAST PLAINS AS A RESULT. THE HIGHER RES MODELS KEEP THE
BEST LIFT AND WAA FURTHER EAST ACROSS WESTERN AND CENTRAL KANSAS
WHICH IS ALSO SUPPORTED BY LOCAL HIGH RES WRF MODEL. WITH THAT
SAID...HAVE KEPT CURRENT FORECAST TRENDED TOWARDS THE HIGHER RES
MODELS KEEPING SILENT POPS THROUGH 06Z WITH CHANCE POPS ACROSS
EASTERN PORTIONS OF BACA AND PROWERS COUNTIES AND SLIGHT POPS
FURTHER NORTH AND WEST INTO KIOWA AND WESTERN PROWERS AND BACA
COUNTIES THEREAFTER. SOUNDINGS INDICATING MAINLY LIGHT RAIN ACROSS
BACA COUNTY THOUGH DO INDICATE A BRIEF PERIOD OF LIGHT FREEZING RAIN
POSSIBLE ACROSS PROWERS AND KIOWA COUNTIES...WITH LATER SHIFTS
NEEDING TO MONITOR LATEST MODELS AND TRENDS. ELSEWHERE...WEAK
WESTERLY FLOW THIS EVENING BECOMES MORE SOUTHWEST AND SLOWLY
INCREASES OVERNIGHT AS EASTERN PACIFIC SYSTEM CONTINUES TO MOVE
ONSHORE ACROSS THE WEST COAST. MAINLY CLEAR SKIES WEST OF THE PLAINS
WILL HELP COOL TEMPS ONCE AGAIN IN THE SAN LUIS VALLEY...WITH THE
WARMEST READINGS EXPECTED ACROSS THE HIGHER TERRAIN ALONG AND WEST
OF THE I-25 CORRIDOR WHERE LEE TROUGHING DEVELOPS OVERNIGHT.
TOMORROW...SOUTHWEST FLOW ALOFT CONTINUES TO INCREASE THROUGH THE
DAY AS THE WEST COAST SYSTEM TRANSLATES INTO THE GREAT BASIN.
MOISTURE PROGGED TO INCREASE FROM WEST TO EAST AND WITH INCREASING
OROGRAPHICS COULD SEE SOME LIGHT SNOW DEVELOPING ACROSS THE HIGHER
TERRAIN OF THE SOUTHWEST MTS BY THE LATE AFTERNOON. LEE TROUGHING
STRENGTHENS ACROSS THE I-25 CORRIDOR WITH BREEZY SOUTH TO SOUTHWEST
WINDS DEVELOPING ACROSS THE PLAINS BOOSTING TEMPS INTO THE LOWER TO
MID 50S. INCREASING CLOUDS AND SLIGHT COOLING ALOFT WILL LEAD TO
SLIGHTLY COOLER TEMPS ACROSS THE HIGHER TERRAIN AND HIGH VALLEYS.
LONG TERM...
(THURSDAY NIGHT THROUGH WEDNESDAY)
..HIGH IMPACT WEATHER TO AFFECT PORTIONS OF SOUTH CENTRAL AND
SOUTHEAST COLORADO THURSDAY NIGHT THROUGH FRIDAY...WITH A TURN
TOWARDS MUCH COLDER TEMPERATURES THROUGH THE WEEKEND INTO EARLY NEXT
WEEK...
A CLOSED UPPER LOW CARVES OUT ACROSS THE GREAT BASIN THURSDAY NIGHT
SENDING STRONG SOUTHWEST FLOW...WITH 110-120+ KT UPPER JET ACROSS
COLORADO BY 12Z FRIDAY. MOISTURE DEEPENS ALONG THE CONTINENTAL
DIVIDE THURSDAY EVENING...WITH SNOW RAMPING UP ALONG THE
OROGRAPHICALLY FAVORED EASTERN SAN JUAN MOUNTAINS. COMBINED WITH
MTN TOP WINDS OF 50-60 KTS...HAZARDOUS CONDITIONS WILL BE POSSIBLE
DUE TO WHITE OUT CONDITIONS IN BLOWING SNOW ACROSS ZONE 68...WHICH
INCLUDES THE WOLF CREEK PASS. HAVE UPGRADED THE WINTER STORM WATCH
TO A BLIZZARD WATCH FOR THIS ZONE. SNOW SHOULD SPREAD NORTH AND
EASTWARD AFTER MIDNIGHT THROUGH THE MORNING HOURS...WITH THE
HEAVIEST SNOW EXPECTED TO FALL BEFORE 18Z WHEN BEST FORCING MOVES
THROUGH. WINDS THEN SHIFT MORE FROM THE WEST TO NORTHWEST FRIDAY
AFTERNOON...WITH THE FOCUS FOR SNOW SHIFTING INTO THE EASTERN
SAWATCH AND WESTERN MOSQUITO RANGES DURING THE AFTERNOON. OVERALL
SNOWFALL AMOUNTS FOR THE BRUNT OF THE EVENT...THURS
NIGHT/FRI...SHOULD RANGE FROM 8 TO 17 INCHES ACROSS THE EASTERN SAN
JUAN MOUNTAINS...WITH AROUND 5 TO 10 INCHES WITH LOCALLY UP TO A
FOOT FOR THE LA GARITAS...EASTERN SAWATCH AND WESTERN MOSQUITO
RANGES. THINK THAT THESE LATTER AREAS WILL EVENTUALLY NEED A WINTER
WEATHER ADVISORY...BUT SINCE SNOW AMOUNTS HAVE BEEN CONSISTENTLY
COMING UP SHORT OF WARNING NUMBERS (12" OR MORE IN GREATER THAN 12
HOURS)...NO WATCHES WILL BE ISSUED AT THIS POINT.
AS THE UPPER JET TRANSLATES ACROSS THE AREA THURSDAY NIGHT THROUGH
FRIDAY...A BORA COLD FRONT WILL MOVE FROM WEST TO EAST ACROSS THE
REGION. HIGHER PEAKS SHOULD START BLOWING FIRST AS MTN TOP WINDS
INCREASE TO AROUND 50-60 KTS. THERE IS QUITE A BIT OF FORWARD SHEAR
WITH THIS SYSTEM...SO THIS DOESN`T APPEAR TO BE A MTN WAVE EVENT.
HOWEVER AS THE NORTH-SOUTH ORIENTED COLD FRONT CROSSES THE
MOUNTAINS...IT COULD BRING A PERIOD OF STRONG GUSTY WINDS INTO THE
ADJACENT LOWER ELEVATIONS OF THE SAN LUIS VALLEY AND THE I-25
CORRIDOR EARLY FRIDAY MORNING AS COLD DENSE AIR SPILLS OVER THE
MOUNTAINS. SFC PRESSURE GRADIENT IS IMPRESSIVE FRIDAY MORNING AS
THE SURFACE LOW DEEPENS ACROSS NORTHEAST COLORADO WHICH SHOULD ALSO
AID IN MIXING STRONG WINDS ALOFT TO THE SURFACE ACROSS THE REMAINDER
OF THE SOUTHEAST PLAINS. ALREADY HAVE A HIGH WIND WATCH OUT AND PLAN TO
MAINTAIN IT. DID BUMP UP THE START TIME OF THE HIGH WIND WATCH TO
MIDNIGHT ACROSS THE SOUTHEAST MTS AS WINDS ALOFT WILL BE INCREASING
AFTER MIDNIGHT...THOUGH THINK STRONGER GUSTS WILL STAY ACROSS THE
HIGHER ELEVATIONS UNTIL FRIDAY MORNING WHEN THE FRONT MOVES THROUGH. WINDS
MAY COME UP JUST SHY OF HIGH WIND CRITERIA ACROSS CENTER PORTIONS OF
THE SAN LUIS VALLEY...BUT VALLEY EDGES...PARTICULARLY ON THE WESTERN
SIDE COULD SEE A PERIOD OF HIGH WINDS FRIDAY MORNING.
BROAD TROFFING REMAINS ACROSS THE GREAT BASIN AND ROCKIES REGION
THROUGH EARLY NEXT WEEK AS ENERGY CONTINUES TO DROP SOUTHWARD OUT OF
CANADA. THIS WILL KEEP VERY COLD AND GENERALLY UNSETTLED CONDITIONS
ACROSS THE REGION THROUGH EARLY NEXT WEEK. TEMPERATURES WILL DROP
OFF CONSIDERABLY ACROSS THE PLAINS...WITH HIGHS STRUGGLING TO REACH
THE 30S BY THE MIDDLE OF NEXT WEEK. MEANWHILE...THE MOUNTAINS AND
VALLEYS WILL BE DROPPING INTO THE NEGATIVE DIGITS AT NIGHT...WITH
KALS LIKELY TO HIT -30 OR BELOW AS A NEW BATCH OF COLD AIR GETS
ENTRENCHED IN THE VALLEY. NEXT WAVE OF ENERGY LIFTS OUT OF THE MEAN
TROF ACROSS SOUTHERN PORTIONS OF THE AREA SAT NIGHT...AND WITH
SHALLOW UPSLOPE AND COLD AIR...WE COULD SEE SOME ADDITIONAL LIGHT
SNOW ACROSS THE MOUNTAINS AND ADJACENT PLAINS...BUT EACH SUCCESSIVE
MODEL RUN HAS BEEN DRIER...SO WILL LEAVE THE SILENT POPS ACROSS THE
PLAINS...WITH GENERALLY ISOLATED TO LOW END SCATTERED POPS ACROSS
THE MOUNTAINS. SAME THING HAPPENS FOR MONDAY NIGHT AS ANOTHER WAVE
OF ENERGY DROPPING INTO THE BASE OF THE TROF CLOSES OFF AN UPPER LOW
ACROSS THE DESSERT SOUTHWEST AND LEADING SHORTWAVE ENERGY EJECTS TO
THE NORTHEAST ACROSS THE AREA. ONCE AGAIN...IF IT OCCURS...ANY
SNOWFALL ACCUMULATIONS APPEAR TO REMAIN LIGHT. GFS AND ECMWF ORPHAN THE
UPPER LOW ACROSS EXTREME SOUTHERN AZ/NRN OLD MEXICO THROUGH
WEDNESDAY WHICH IS TOO FAR SOUTH TO BRING ANY PRECIPITATION TO THE
AREA THROUGH WEDNESDAY. TEMPERATURES SHOULD SLOWLY MODERATE SOME
INTO THE MIDDLE OF NEXT WEEK. -KT
AVIATION...
VFR CONDITIONS TO PREVAIL AT KCOS AND KPUB THROUGH THE NEXT 24
HOURS WITH GENERALLY LIGHT WINDS THROUGH TONIGHT. BREEZY SOUTH TO
SOUTHWEST WINDS OF 15-20KTS ARE EXPECTED TO DEVELOP AFT 18Z THU.
KALS HAD STRONG RADIATIONAL COOLING AND SCT001 TO LOCALLY BKN001
ACROSS THE VALLEY FLOOR LATE LAST NIGHT AND EARLY THIS MORNING...BUT
VIS DID NOT DROP BELOW MFVR. WOULD THINK THE SAME FOR TONIGHT...AS
TEMPS DID NOT WARM AS MUCH AS EXPECTED. AT ANY RATE...VFR CONDITIONS
EXPECTED THROUGH 06Z THU...WITH LOCAL IFR AND LIFR CIGS THEN
POSSIBLE THROUGH 16Z. VFR AGAIN AFT 16Z THU. -MW
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM FRIDAY MORNING THROUGH FRIDAY AFTERNOON FOR
COZ069>071-083>089-093>099.
HIGH WIND WATCH FROM LATE THURSDAY NIGHT THROUGH FRIDAY
AFTERNOON FOR COZ072>082.
BLIZZARD WATCH FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON
FOR COZ068.
&&
$$
81/10
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1157 AM CST THU JAN 10 2013
.DISCUSSION...
ISSUED 1040 AM CST THU JAN 10 2013
FORECAST GENERALLY ON TRACK TODAY AND JUST A FEW MINOR ADJUSTMENTS
WITH INCREASING WIND SPEEDS A BIT AND LIMIT THUNDERSTORM CHANCES
TO AREAS SOUTH OF I-72 THIS AFTERNOON.
SCATTERED LIGHT RAIN SHOWERS HAVE SPREAD NORTHWARD INTO CENTRAL
IL BY LATE MORNING WITH HEAVIER SHOWERS OVER SOUTHERN IL FROM I-64
SOUTH AND EAST OF I-57 AND LIFTING NORTHWARD. LATE MORNING
SURFACE MAP SHOWS 1011 MB LOW PRESSURE ALONG THE WESTERN RED RIVER
VALLEY ON THE OK/TX BORDER WHILE 557 DM 500 MB LOW NEAR THAT LOCATION.
QUICKER HRRR MODEL HANDLING QPF FIELDS BETTER THIS MORNING THAN
SLOWER NAM AND RAP MODELS SO LEANED ON THIS MODEL FOR FORECAST
INTO THIS EVENING. RAIN SHOWERS TO BECOME MORE WIDESPREAD THIS
AFTERNOON AND EVENING AND HEAVIEST RAINFALL TO OCCUR SE OF I-55
WITH ISOLATED THUNDERSTORMS POSSIBLE. RAINFALL AMOUNTS TODAY AND
THU TO RANGE FROM 1-1.25 INCHES WITH LOCALLY 1.25-1.5 INCHES SW OF
SPRINGFIELD AND SE OF I-70. LITTLE WABASH RIVER AT CLAY CITY
FORECAST TO RISE ABOVE THE 16 FOOT FLOOD STAGE FRIDAY AFTERNOON.
MODELS EJECT STRONG CUTOFF NEGATIVE TITLED UPPER LEVEL LOW NE INTO
WEST CENTRAL MO BY MIDNIGHT TONIGHT AND NORTHWEST IL BY DAWN FRI.
IMPRESSIVE PRECIPITATABLE WATER VALUES OF 1.25-1.50 INCHES SPREAD
INTO CENTRAL/SE IL BY THIS EVENING AIDED BY 35-50 KT SSW 850 MB
JET WITH HIGHEST PRECIP VALUES IN SE IL. TEMPS CURRENTLY IN THE
MID 30S TO LOWER 40S WITH COOLEST READINGS NEAR 35F AT GALESBURG
AND MACOMB WHERE LINGERING 1-2 INCH SNOW PACK. HIGHS TO REACH THE
MID 40S NORTH AND LOWER 50S SE IL. TEMPS TO SLOWLY RISE TONIGHT AS
WARM FRONT LIFTS NORTHWARD TO BETWEEN 50-55F BY SUNRISE FRIDAY.
07
&&
.AVIATION...
ISSUED 1155 AM CST THU JAN 10 2013
VFR CONDITIONS AT NOON ACROSS THE CENTRAL IL TERMINAL AIRPORTS
WILL QUICKLY DETERIORATE DURING THE AFTERNOON WITH IFR VSBYS AND
CEILINGS GRADUALLY SETTING IN WITH DEVELOPING LIGHT TO MODERATE
RAIN SHOWERS. COULD BE ISOLATED THUNDERSTORMS LATER THIS AFTERNOON
AND EVENING WITH BEST CHANCES ALONG AND SOUTH OF I-72 BUT TOO
ISOLATED IN NATURE TO PIN POINT IN TAFS AT THIS TIME. RAIN SHOWERS
SHOULD DIMINISH FROM SW TO NE DURING BETWEEN 08Z-11Z OVERNIGHT
WITH IFR CEILINGS AND VSBYS LINGERING WITH LOW CLOUDS AND FOG.
HAVE CEILINGS AND VSBYS GRADUALLY LIFTING TO MVFR BY LATE FRI
MORNING WITH BMI AND CMI LATEST TO OCCUR NEAR OR AFTER 16Z. ESE
WINDS 10-15 KTS TO TURN SE AFTER 21Z THIS AFTERNOON AND
EVENING...THEN TURN SSW DURING OVERNIGHT AS WARM FRONT LIFTS
NORTHWARD ACROSS CENTRAL IL.
557 DM 500 MB CUTOFF LOW ALONG THE RED RIVER ON THE TX/OK BORDER
AND 1011 MB SURFACE LOW NEARBY TO EJECT NE INTO WEST CENTRAL MO BY
06Z/MIDNIGHT TONIGHT...INTO CENTRAL/NW IL BY 12Z/6 AM FRI AND NEAR
SE LOWER MI AND OHIO BORDER BY 18Z/NOON FRI. IFR CONDITIONS
CURRENTLY OVER MUCH OF MO AND SOUTHERN IL TO SPREAD NE ACROSS
CENTRAL IL DURING EARLY/MID AFTEROON AND LINGER THROUGH EARLY FRI
MORNING THEN LIFT TO MVFR BETWEEN 14Z-16Z FRIDAY. VSBYS COULD GET
BELOW 1 MILE AT TIMES TONIGHT AND CELINGS BELOW 500 FT (LIFR) AT
PIA AND BMI WHERE FOG MORE WIDESPREAD WITH THE RAIN SHOWERS.
07
&&
.PREV DISCUSSION...
ISSUED 312 AM CST THU JAN 10 2013
THE UPPER LOW THAT WE HAVE BEEN TRACKING THE LAST FEW DAYS HAS
MADE SOME GOOD PROGRESS OVER THE LAST SEVERAL HOURS...AND WAS
CENTERED IN CENTRAL TEXAS AT 3 AM PER WATER VAPOR IMAGERY. LARGE
AREA OF RAIN HAS BEGUN SPREADING NORTHWARD ACROSS SOUTHERN MISSOURI
AND KENTUCKY. FORECAST CONCERNS INVOLVING THIS FEATURE INCLUDE
HEAVY RAIN POTENTIAL...AS WELL AS ABNORMALLY MILD WEATHER OVER THE
NEXT 24-36 HOURS. THIS WEEKEND...THE POTENTIAL FOR WINTRY MIXTURE
IS A CONCERN FOR SATURDAY NIGHT AND EARLY SUNDAY.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
RAIN WILL CONTINUE TO SPREAD NORTHWARD TODAY AS THE UPPER LOW
LIFTS INTO KANSAS. LATEST MODEL GUIDANCE SUGGESTS AREAS NORTH OF
I-74 MAY HOLD OFF ON THE RAIN UNTIL AROUND MIDDAY...BUT WILL
CONTINUE WITH CATEGORICAL POPS EVERYWHERE THIS AFTERNOON AND MUCH
OF TONIGHT. MOST OF THE MODELS CONTINUE TO SHOW THE LOW SHEARING
OUT INTO AN OPEN WAVE AS IT LIFTS TOWARD NORTHERN ILLINOIS... AND
PRECIPITATION SHOULD RAPIDLY TAPER OFF FROM WEST TO EAST AFTER
MIDNIGHT. DRY WEATHER IS EXPECTED ON FRIDAY AND FRIDAY NIGHT.
HAVE MAINTAINED THE NON-DIURNAL TEMPERATURE TRENDS TONIGHT AND
FRIDAY NIGHT...AND THE UNSEASONABLY MILD HIGHS ON FRIDAY. HAVE
GONE WITH HIGHS NEAR 60 IN MOST AREAS...WITH LOWER 60S SOUTH OF
I-70. TEMPERATURES WILL BE APPROACHING RECORDS IN MANY AREAS.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
FOCUS TURNS TOWARD DEEP LONG WAVE TROUGHING OVER THE ROCKIES
EARLY THIS WEEKEND...RESULTING IN RIDGING ALONG THE EAST COAST.
THE COLD FRONT WHICH WILL CROSS THE AREA EARLY ON SATURDAY WILL
BECOME HUNG UP ALONG THE OHIO RIVER BY SATURDAY EVENING...AS IT
BECOMES PARALLEL TO THE UPPER FLOW. WAVES OF LOW PRESSURE RIDING
NORTHEAST ALONG THE FRONT WILL SPREAD PRECIPITATION BACK NORTHWARD
SATURDAY EVENING ACROSS MOST OF THE CWA...LINGERING MUCH OF THE
NIGHT. STILL AM CONCERNED ABOUT POTENTIAL FOR FREEZING RAIN OR
SLEET. LATEST MODEL GUIDANCE HAS SHIFTED THE AXIS OF CONCERN A BIT
FURTHER EAST...WITH A WARM NOSE OF 850 MB TEMPERATURES OF 5 TO 7
DEGREES CELSIUS FROM ABOUT CHAMPAIGN AND DANVILLE SOUTHWEST
THROUGH TAYLORVILLE ESPECIALLY AFTER MIDNIGHT. AREAS ALONG AND
WEST OF I-55 WILL TREND MORE TOWARD SNOW DURING THE EVENING...
WITH SOME POTENTIAL FOR A COUPLE INCHES OF ACCUMULATION. THE
SOUTHEAST CWA IS EXPECTED TO REMAIN WARM ENOUGH FOR RAIN SATURDAY
NIGHT AND SUNDAY.
THE FRONT WILL REMAIN HUNG FOR A FEW DAYS...BUT IS EXPECTED TO SAG
FAR ENOUGH SOUTH THAT PRECIPITATION CHANCES SHOULD BE SOUTH OF OUR
AREA FROM MONDAY ONWARD. HOWEVER...THE LATEST ECMWF HINTS THAT
SOME LOW POPS MAY NEED TO BE ADDED IN THE FAR SOUTHEAST CWA MONDAY
AND MONDAY NIGHT. WILL CONTINUE TO MONITOR THIS POTENTIAL.
HYDROLOGY...
HAVE SOME CONCERNS REGARDING HEAVY RAIN POTENTIAL OVER THE NEXT
COUPLE DAYS. HIGH PRECIPITABLE WATER VALUES OF AROUND 1.5 INCHES
OBSERVED ON THE EVENING UPPER AIR SOUNDING FROM LITTLE ROCK... AND
NAM/GFS MODELS SHOW THIS ADVECTING NORTHEAST INTO ILLINOIS THIS
AFTERNOON...PERSISTING THROUGH ABOUT MIDNIGHT. PER CLIMATOLOGY...
SUCH VALUES IN THIS AREA IN JANUARY ARE ABOUT OFF THE CHARTS.
CURRENTLY AM FORECASTING A WIDESPREAD INCH OF RAIN OVER THE AREA
THROUGH FRIDAY MORNING...WITH SOME LOCALLY HIGHER AMOUNTS. WITH
THE COLDER AIR THAT HAD BEEN PRESENT THE LAST SEVERAL DAYS...THE
GROUND IS SOMEWHAT FROZEN AND SOME RUNOFF IS LIKELY. MOST OF THE
SNOW IS PRETTY MUCH GONE NOW EXCEPT IN THE NORTHWEST AND SOUTHEAST
CORNERS OF THE CWA...SO SNOW MELT SHOULD NOT BE MUCH OF A PROBLEM.
MOST RIVERS HAVE BEEN RUNNING RATHER LOW AND SHOULD BE ABLE TO
TAKE ON THIS RUNOFF...BUT SOME MINOR FLOODING IS POSSIBLE ALONG
THE LITTLE WABASH RIVER. HOWEVER...WITH THE FRONT HANGING UP NEAR
THE OHIO RIVER SATURDAY EVENING...ANOTHER ROUND OF HEAVIER RAIN IS
POSSIBLE SOUTH OF I-70 THIS WEEKEND.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1044 AM CST THU JAN 10 2013
.DISCUSSION...
ISSUED 1040 AM CST THU JAN 10 2013
FORECAST GENERALLY ON TRACK TODAY AND JUST A FEW MINOR ADJUSTMENTS
WITH INCREASING WIND SPEEDS A BIT AND LIMIT THUNDERSTORM CHANCES
TO AREAS SOUTH OF I-72 THIS AFTERNOON.
SCATTERED LIGHT RAIN SHOWERS HAVE SPREAD NORTHWARD INTO CENTRAL
IL BY LATE MORNING WITH HEAVIER SHOWERS OVER SOUTHERN IL FROM I-64
SOUTH AND EAST OF I-57 AND LIFTING NORTHWARD. LATE MORNING
SURFACE MAP SHOWS 1011 MB LOW PRESSURE ALONG THE WESTERN RED RIVER
VALLEY ON THE OK/TX BORDER WHILE 557 DM 500 MB LOW NEAR THAT LOCATION.
QUICKER HRRR MODEL HANDLING QPF FIELDS BETTER THIS MORNING THAN
SLOWER NAM AND RAP MODELS SO LEANED ON THIS MODEL FOR FORECAST
INTO THIS EVENING. RAIN SHOWERS TO BECOME MORE WIDESPREAD THIS
AFTERNOON AND EVENING AND HEAVIEST RAINFALL TO OCCUR SE OF I-55
WITH ISOLATED THUNDERSTORMS POSSIBLE. RAINFALL AMOUNTS TODAY AND
THU TO RANGE FROM 1-1.25 INCHES WITH LOCALLY 1.25-1.5 INCHES SW OF
SPRINGFIELD AND SE OF I-70. LITTLE WABASH RIVER AT CLAY CITY
FORECAST TO RISE ABOVE THE 16 FOOT FLOOD STAGE FRIDAY AFTERNOON.
MODELS EJECT STRONG CUTOFF NEGATIVE TITLED UPPER LEVEL LOW NE INTO
WEST CENTRAL MO BY MIDNIGHT TONIGHT AND NORTHWEST IL BY DAWN FRI.
IMPRESSIVE PRECIPITATABLE WATER VALUES OF 1.25-1.50 INCHES SPREAD
INTO CENTRAL/SE IL BY THIS EVENING AIDED BY 35-50 KT SSW 850 MB
JET WITH HIGHEST PRECIP VALUES IN SE IL. TEMPS CURRENTLY IN THE
MID 30S TO LOWER 40S WITH COOLEST READINGS NEAR 35F AT GALESBURG
AND MACOMB WHERE LINGERING 1-2 INCH SNOW PACK. HIGHS TO REACH THE
MID 40S NORTH AND LOWER 50S SE IL. TEMPS TO SLOWLY RISE TONIGHT AS
WARM FRONT LIFTS NORTHWARD TO BETWEEN 50-55F BY SUNRISE FRIDAY.
07
&&
.AVIATION...
ISSUED 557 AM CST THU JAN 10 2013...FOR THE 12Z TAFS
RAIN WILL OVERSPREAD THE AREA FROM THE SOUTH AS LOW PRESSURE IN
EASTERN TEXAS LIFTS NORTH INTO THE PLAINS. BASED ON FORECAST
SOUNDINGS AND UPSTREAM OBSERVATIONS...WE EXPECT VFR CONDITIONS
WILL QUICKLY DROP TO IFR AFTER RAIN STARTS. CIGS WILL DIP BELOW 1K
FT WITH VIS MOST LIKELY IN THE MVFR RANGE DURING RAIN.
RAIN WILL BE SCATTERED DURING THE DAY...BUT IFR CONDITIONS ARE
GENERALLY EXPECTED TO CONTINUE DURING BREAKS IN THE RAIN. RAIN
WILL BECOME MORE STEADY TONIGHT AS THE WARM FRONT LIFTS NORTH
THROUGH ILLINOIS AND THE SURFACE LOW LIFTS NORTH THROUGH MISSOURI
AND IOWA. RAINFALL SHOULD DIMINISH AFTER MIDNIGHT...WITH RAIN
ENDING IN MOST AREAS BY SUNRISE ON FRIDAY. PREVAILING CONDITIONS
MAY DIP TO LIFR OR VLIFR THIS EVENING AND OVERNIGHT DUE TO LOW
CEILINGS. FOG WILL BE POSSIBLE AS WELL...BUT WIDESPREAD DENSE FOG
IS NOT EXPECTED AT THIS POINT.
WINDS WILL BE SOUTHEAST AND INCREASE TO 12-15KT TODAY...THEN SHIFT
TO THE SOUTHWEST AFTER THE WARM FRONT PASSES TONIGHT.
SHIMON
&&
.PREV DISCUSSION...
ISSUED 312 AM CST THU JAN 10 2013
THE UPPER LOW THAT WE HAVE BEEN TRACKING THE LAST FEW DAYS HAS
MADE SOME GOOD PROGRESS OVER THE LAST SEVERAL HOURS...AND WAS
CENTERED IN CENTRAL TEXAS AT 3 AM PER WATER VAPOR IMAGERY. LARGE
AREA OF RAIN HAS BEGUN SPREADING NORTHWARD ACROSS SOUTHERN MISSOURI
AND KENTUCKY. FORECAST CONCERNS INVOLVING THIS FEATURE INCLUDE
HEAVY RAIN POTENTIAL...AS WELL AS ABNORMALLY MILD WEATHER OVER THE
NEXT 24-36 HOURS. THIS WEEKEND...THE POTENTIAL FOR WINTRY MIXTURE
IS A CONCERN FOR SATURDAY NIGHT AND EARLY SUNDAY.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
RAIN WILL CONTINUE TO SPREAD NORTHWARD TODAY AS THE UPPER LOW
LIFTS INTO KANSAS. LATEST MODEL GUIDANCE SUGGESTS AREAS NORTH OF
I-74 MAY HOLD OFF ON THE RAIN UNTIL AROUND MIDDAY...BUT WILL
CONTINUE WITH CATEGORICAL POPS EVERYWHERE THIS AFTERNOON AND MUCH
OF TONIGHT. MOST OF THE MODELS CONTINUE TO SHOW THE LOW SHEARING
OUT INTO AN OPEN WAVE AS IT LIFTS TOWARD NORTHERN ILLINOIS... AND
PRECIPITATION SHOULD RAPIDLY TAPER OFF FROM WEST TO EAST AFTER
MIDNIGHT. DRY WEATHER IS EXPECTED ON FRIDAY AND FRIDAY NIGHT.
HAVE MAINTAINED THE NON-DIURNAL TEMPERATURE TRENDS TONIGHT AND
FRIDAY NIGHT...AND THE UNSEASONABLY MILD HIGHS ON FRIDAY. HAVE
GONE WITH HIGHS NEAR 60 IN MOST AREAS...WITH LOWER 60S SOUTH OF
I-70. TEMPERATURES WILL BE APPROACHING RECORDS IN MANY AREAS.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
FOCUS TURNS TOWARD DEEP LONG WAVE TROUGHING OVER THE ROCKIES
EARLY THIS WEEKEND...RESULTING IN RIDGING ALONG THE EAST COAST.
THE COLD FRONT WHICH WILL CROSS THE AREA EARLY ON SATURDAY WILL
BECOME HUNG UP ALONG THE OHIO RIVER BY SATURDAY EVENING...AS IT
BECOMES PARALLEL TO THE UPPER FLOW. WAVES OF LOW PRESSURE RIDING
NORTHEAST ALONG THE FRONT WILL SPREAD PRECIPITATION BACK NORTHWARD
SATURDAY EVENING ACROSS MOST OF THE CWA...LINGERING MUCH OF THE
NIGHT. STILL AM CONCERNED ABOUT POTENTIAL FOR FREEZING RAIN OR
SLEET. LATEST MODEL GUIDANCE HAS SHIFTED THE AXIS OF CONCERN A BIT
FURTHER EAST...WITH A WARM NOSE OF 850 MB TEMPERATURES OF 5 TO 7
DEGREES CELSIUS FROM ABOUT CHAMPAIGN AND DANVILLE SOUTHWEST
THROUGH TAYLORVILLE ESPECIALLY AFTER MIDNIGHT. AREAS ALONG AND
WEST OF I-55 WILL TREND MORE TOWARD SNOW DURING THE EVENING...
WITH SOME POTENTIAL FOR A COUPLE INCHES OF ACCUMULATION. THE
SOUTHEAST CWA IS EXPECTED TO REMAIN WARM ENOUGH FOR RAIN SATURDAY
NIGHT AND SUNDAY.
THE FRONT WILL REMAIN HUNG FOR A FEW DAYS...BUT IS EXPECTED TO SAG
FAR ENOUGH SOUTH THAT PRECIPITATION CHANCES SHOULD BE SOUTH OF OUR
AREA FROM MONDAY ONWARD. HOWEVER...THE LATEST ECMWF HINTS THAT
SOME LOW POPS MAY NEED TO BE ADDED IN THE FAR SOUTHEAST CWA MONDAY
AND MONDAY NIGHT. WILL CONTINUE TO MONITOR THIS POTENTIAL.
HYDROLOGY...
HAVE SOME CONCERNS REGARDING HEAVY RAIN POTENTIAL OVER THE NEXT
COUPLE DAYS. HIGH PRECIPITABLE WATER VALUES OF AROUND 1.5 INCHES
OBSERVED ON THE EVENING UPPER AIR SOUNDING FROM LITTLE ROCK... AND
NAM/GFS MODELS SHOW THIS ADVECTING NORTHEAST INTO ILLINOIS THIS
AFTERNOON...PERSISTING THROUGH ABOUT MIDNIGHT. PER CLIMATOLOGY...
SUCH VALUES IN THIS AREA IN JANUARY ARE ABOUT OFF THE CHARTS.
CURRENTLY AM FORECASTING A WIDESPREAD INCH OF RAIN OVER THE AREA
THROUGH FRIDAY MORNING...WITH SOME LOCALLY HIGHER AMOUNTS. WITH
THE COLDER AIR THAT HAD BEEN PRESENT THE LAST SEVERAL DAYS...THE
GROUND IS SOMEWHAT FROZEN AND SOME RUNOFF IS LIKELY. MOST OF THE
SNOW IS PRETTY MUCH GONE NOW EXCEPT IN THE NORTHWEST AND SOUTHEAST
CORNERS OF THE CWA...SO SNOW MELT SHOULD NOT BE MUCH OF A PROBLEM.
MOST RIVERS HAVE BEEN RUNNING RATHER LOW AND SHOULD BE ABLE TO
TAKE ON THIS RUNOFF...BUT SOME MINOR FLOODING IS POSSIBLE ALONG
THE LITTLE WABASH RIVER. HOWEVER...WITH THE FRONT HANGING UP NEAR
THE OHIO RIVER SATURDAY EVENING...ANOTHER ROUND OF HEAVIER RAIN IS
POSSIBLE SOUTH OF I-70 THIS WEEKEND.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
531 PM CST FRI JAN 11 2013
.AVIATION...
CONDITIONS HAVE IMPROVED TO VFR AT KBRL/KMLI/KCID TERMINALS AND
ARE NOW EXPECTED TO IMPROVE FROM VLIFR AT KDBQ TO VFR CONDITIONS
IN THE NEXT 2-6 HOURS. A STRONG BUT DRY ARCTIC COLD FRONT WILL
MOVE THROUGH EASTERN IOWA AND NORTHERN ILLINOIS BETWEEN 12/09Z
AND 12/12Z AT ALL TERMINALS. SOUTH TO SOUTHWEST WINDS OF 10 TO 20
KTS WILL SHIFT TO WEST AND NORTHWEST AT 10 TO 20 KTS. SKIES WILL
BE SCT-BKN WITH CIGS AOA 4K AGL ALL TERMINALS ONCE KDBQ TERMINAL
IMPROVES THIS EVENING.
NICHOLS
&&
.PREV DISCUSSION... /ISSUED 302 PM CST FRI JAN 11 2013/
SYNOPSIS...
12Z UA ANALYSIS HAS A STRONG SYSTEM OVER THE ROCKIES WITH STRONG
SOUTHWEST FLOW FROM NORTHERN MEXICO INTO THE GREAT LAKES.
SATELLITE TRENDS THROUGH MID AFTERNOON INDICATE THE LOW CLOUDS ARE
BREAKING UP AS DEEPER MIXING OCCURS BUT MID AND HIGH LEVEL CLOUDS
ARE STREAMING IN OVER THE REMAINING LOW CLOUDS.
18Z SFC ANALYSIS HAS A LOW NORTH OF KATY WITH ANOTHER NORTHEAST OF
KLIC. A STRONG COLD FRONT CONNECTED BOTH LOWS AND THERE WERE
NUMEROUS TROFS FROM THE GREAT LAKES BACK INTO THE SOUTHERN PLAINS.
DEW POINTS WERE IN THE TEENS AND 20S ACROSS THE NORTHERN PLAINS
WITH 30S AND 40S ACROSS MUCH OF THE GREAT LAKES AND MIDWEST. DEW
POINTS IN THE 50S AND 60S RAN FROM THE OHIO VALLEY INTO THE DEEP
SOUTH.
SHORT TERM...LATE THIS AFTERNOON THROUGH SATURDAY
WE ARE DEALING WITH ADVECTION FOG. IN ADVECTION FOG YOU CAN HAVE
EXTREMELY DENSE FOG EVEN THOUGH WINDS ARE 10 TO 20 MPH. ALBEIT FAR
FROM PERFECT...THE RAP MODEL TRENDS STRONGLY POINT TO DENSE FOG
CONTINUING INTO THE EVENING ACROSS THE NORTHERN CWFA.
AS FOR HEADLINES...THE DENSE FOG ADVISORY WILL BE EXTENDED UNTIL
MIDNIGHT FROM DUBUQUE ON WEST IN THE HWY 20 CORRIDOR. PER
OBSERVATIONS AND WHAT WEB CAMS ARE AVAILABLE...THE NORTHERN PARTS
OF LINN/JONES/JACKSON COUNTIES IN IOWA AND STEPHENSON COUNTY IN
ILLINOIS STILL HAVE DENSE FOG OVER THEM. THUS THESE COUNTIES AND
JO DAVIESS COUNTY WILL HAVE THE DENSE FOG ADVISORY EXTENDED
THROUGH 6 PM.
THE POSSIBILITY DOES EXIST THAT THE HEADLINES MAY BE DROPPED
EARLY. THAT WILL DEPEND UPON STRONGER WINDS PROMOTING MIXING OF
THE BOUNDARY LAYER TO CAUSE THE FOG TO LIFT.
AFTER MIDNIGHT...A STRONG COLD FRONT WILL SWEEP THROUGH THE CWFA.
THIS FRONT WILL SCOUR OUT WHAT REMAINING FOG IS ACROSS THE AREA.
VERY BRISK CONDITIONS WILL BE SEEN ACROSS THE AREA ON SATURDAY
BEHIND THE FRONT.
THE STRENGTH OF THE CAA ON SATURDAY WOULD NORMALLY RESULT IN
UNSTABLE CONDITIONS WITH CONVECTIVE SHOWERS DEVELOPING. HOWEVER...
LOW LEVEL LAPSE RATES REMAIN QUITE STABLE DURING THE DAY AND FCST
SOUNDINGS SHOW A VERY PRONOUNCED INVERSION ACROSS THE AREA. THUS
SATURDAY WILL REMAIN DRY.
LOW TEMPERATURES TONIGHT WILL OCCUR AROUND 8 AM SATURDAY. THE HIGH
TEMPERATURES FOR THE DAYLIGHT HOURS ON SATURDAY WILL OCCUR BETWEEN
8 AND 10 AM FOLLOWED BY SLOWLY FALLING TEMPERATURES. TEMPERATURES
MAY REBOUND A LITTLE DURING THE AFTERNOON BUT WILL BE BELOW THE
MORNING HIGHS. ..08..
LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
SATURDAY NIGHT AND SUNDAY TO BE THE TRICKY PERIOD. LAST NIGHT THE
ECMWF TOOK A JOG TO THE NORTHWEST WITH A SHORTWAVE AND SURFACE
LOW THAT MOVES FROM EAST TEXAS NORTHEAST UP THE OHIO VALLEY. IT
APPEARS TO BE BRINGING THE WHOLE FEATURE FARTHER NORTHWEST...AS
WELL AS TAKING ADVANTAGE OF SOME DEEPER FRONTOGENESIS THAT SEEMS
TO BE FORMING ON THE NORTH SIDE OF THE FEATURE. THIS
MORNING...MORE OF THE MODELS FOLLOWED THAT TREND...AND ARE NOW
BRINGING A NICE SWATH OF SNOW TO THE FORECAST AREA. AREAS
SOUTHEAST OF A LINE FROM CEDAR RAPIDS TO DUBUQUE ARE NOW LOOKING
AT A NICE 1 TO POSSIBLY 3 INCH SNOWFALL EVENT...ASSUMING WE CAN
GET ENOUGH MOISTURE INTO THE AREA AND THE ECMWF AND GFS
ISENTROPIC AND FRONTOGENESIS LIFT PROGS ARE CORRECT. HAVE RAISED
POPS...BUT IF THIS TREND CONTINUES WITH TONIGHTS MODEL RUNS...WE
COULD RAISE POPS AGAIN.
SUNDAY NIGHT AND MONDAY TO BE COLD...ESPECIALLY IF WE CAN GET
SOME SNOW ON THE GROUND TO ENHANCE THE STRONG SURFACE RIDGE THAT
WILL BE SITTING OVER THE AREA BY EARLY MONDAY MORNING. AT THIS
TIME IT LOOKS LIKE WE MAY SEE SOME SINGLE DIGITS IN THE NORTHWEST
PORTIONS OF THE FORECAST AREA. IF WE DO GET THE NEW
SNOWPACK...NEARLY THE WHOLE CWA COULD HAVE SINGLE DIGIT MINS WITH
NEAR ZERO VALUES POSSIBLE NORTHWEST. HIGHS ON MONDAY TO STILL BE
CHILLY WITH THE RIDGE STILL OVERHEAD...AND CURRENTLY HAVE MID TO
UPPER 20S.
TUESDAY THE MAIN UPPER LEVEL TROUGH TO SLOWLY MOVE
OVERHEAD...INCREASING CLOUD COVER SOMEWHAT AND WITH SOME WEAK
WARM AIR ADVECTION BEGINNING ALOFT SOME MODERATION OF TEMPERATURES
IS POSSIBLE.
WEDNESDAY A STRONG CLIPPER IS LIKELY TO MOVE OUT OF CANADA IN THE
LONGWAVE TROUGH. THIS SYSTEM TO STAY MOSTLY NORTH OF THE
AREA...BUT IT WILL PULL SOME WARMER TEMPERATURES ALOFT OVER THE
AREA...FOR A CONTINUATION OF THE WARMING TREND STARTED ON TUESDAY.
HIGHS WEDNESDAY AFTERNOON SHOULD BE IN THE 30S NEARLY EVERYWHERE.
WITH THE CLIPPER NOW HAVING MOVED OFF TO THE EAST BY WEDNESDAY
NIGHT...A FRESH SHOT OF COLDER AIR WILL MOVE INTO THE CWA FROM
THE NORTH AS THE UPPER LEVEL TROUGH AXIS SHARPENS. IT LOOKS LIKE A
SHORTWAVE MAY DIVE THROUGH THE AREA THURSDAY...BUT SOME MODELS
KEEP IT TOO FAR NORTH TO AFFECT THE AREA...SO HAVE LEFT FORECAST
DRY FOR NOW. FRIDAY LOOKS COLD AND DRY AS WELL.
LE
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL 6 PM CST THIS EVENING FOR JACKSON-JONES-
LINN.
DENSE FOG ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BUCHANAN-
DELAWARE-DUBUQUE.
IL...DENSE FOG ADVISORY UNTIL 6 PM CST THIS EVENING FOR JO DAVIESS-
STEPHENSON.
MO...NONE.
&&
$$
NICHOLS
AREA FORECAST DISCUSSION...CORRECTED RECORD HIGHS FOR FRIDAY
NWS QUAD CITIES IA IL
319 PM CST THU JAN 10 2013
.SYNOPSIS...
12Z UA ANALYSIS HAS THE CUT OFF LOW IN WEST TEXAS WITH A 850MB
WARM FRONT RUNNING FROM CENTRAL OKLAHOMA INTO SOUTHEAST KANSAS. A
VERY SHARP 850MB MOISTURE GRADIENT RAN FROM NORTHWEST MISSOURI
INTO THE OHIO VALLEY. RADAR TRENDS THROUGH THE MORNING AND
AFTERNOON SHOW PLENTY OF VIRGA FROM NORTHERN IOWA INTO NORTHERN
ILLINOIS WITH SFC RAIN FROM SOUTHERN IOWA INTO CENTRAL ILLINOIS.
18Z SFC ANALYSIS HAS THE LOW IN SOUTHWEST OKLAHOMA WITH A
DEVELOPING BOUNDARY FROM CENTRAL OKLAHOMA TO NEAR KMEM. DEW POINTS
WERE IN THE 20S ACROSS THE GREAT LAKES WITH 30S AND 40S FROM THE
CENTRAL PLAINS INTO THE OHIO VALLEY. DEW POINTS IN THE 50S WERE IN
THE LOWER MISSISSIPPI VALLEY.
&&
.SHORT TERM...LATE THIS AFTERNOON AND TONIGHT
THE MOISTURE SURGE COMING UP FROM THE SOUTH IS STARTING TO WIN
OVER THE DRY AIR. SPOTTY RAIN OR DRIZZLE IS NOW OVER ROUGHLY THE
SOUTHERN HALF OF THE CWFA WITH SPRINKLES OR VERY SPOTTY RAIN
DEVELOPING OVER THE NORTHERN HALF.
RAP TRENDS INDICATE THAT A VERY RAPID TOP DOWN SATURATION WILL
OCCUR LATE THIS AFTERNOON. SO BY THE EVENING COMMUTE THERE SHOULD
BE FAIRLY WIDESPREAD VERY LIGHT RAIN OR DRIZZLE OCCURRING ACROSS
THE AREA.
TEMPERATURES WILL SLOWLY CLIMB LATE THIS AFTERNOON AS MOISTURE
CONTINUES TO SURGE INTO THE AREA. HIGH TEMPERATURES FOR THE
VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME FRAME.
LIKEWISE...OVERNIGHT LOWS WILL LIKELY OCCUR IN THE 7-8 PM TIME
FRAME FOLLOWED BY STEADY OR SLOWLY RISING TEMPERATURES.
TONIGHT...STRONG FORCING MOVES ACROSS THE AREA DURING THE EVENING
WITH A FULLY SATURATED ATMOSPHERE. THE HEAVY RAIN TOOL SUGGESTS
THE EVENING HOURS WILL LIKELY ACCOUNT FOR MUCH OF THE RAINFALL
FROM THIS EVENT. AFTER MIDNIGHT...WIDESPREAD DRIZZLE WILL BE SEEN
BUT ANOTHER ROUND OF FORCING WILL LIKELY ALLOW SOME ADDITIONAL
RAIN TO OCCUR.
ANOTHER CONCERN TONIGHT IS FOG. THERE IS STILL A RESPECTABLE SNOW
FIELD OVER ROUGHLY THE NORTHERN THIRD OF THE CWFA. ADVECTING
MOISTURE INTO THE AREA ALONG WITH RAIN SHOULD ALLOW PATCHY OR SOME
AREAS OF FOG TO DEVELOP LATE THIS EVENING AS WINDS DIMINISH. AFTER
MIDNIGHT WINDS DROP OFF ACROSS THE NORTHWEST THIRD TO 40 PERCENT
OF THE CWFA WITH THE PASSAGE OF THE SFC LOW. AT THIS TIME THE RISK
FOR DENSE FOG WILL BE THE GREATEST.
THEREFORE...WILL ISSUE A DENSE FOG ADVISORY FOR THE MAIN SNOW
FIELD AND WHERE WINDS ARE PROGGED TO BE LIGHT. IT IS HIGHLY LIKELY
THAT THE DENSE FOG ADVISORY MAY HAVE TO BE EXPANDED DURING THE
EVENING OR OVERNIGHT HOURS. ..08..
.LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
HIGH TEMPERATURES FOR FRIDAY ARE A LARGE QUESTION MARK THIS
FORECAST. THE MAIN COMPLICATING FACTOR IS IN HOW QUICKLY THE LOW
CLOUDS CLEAR FROM SOUTH TO NORTH WITH THE ASSOCIATED CLEARING OF THE
FOG AND DRIZZLE. MODELS HAVE BEEN STRUGGLING WITH THIS ISSUE...WITH
MANY OF THEM KEEPING A TRAPPED LOWER LAYER OF LOW CLOUDS AND FOG
WITH A STRONG ELEVATED MIXED LAYER OVER THE TOP OF IT.
HOWEVER...THEY ALSO DEPICT STRONG SURFACE WINDS...WHICH DOES NOT
MATCH WELL WITH A TRAPPED LOW LEVEL INVERSION. A LOOK AT THE MODEL
INITIALIZATION SHOWS THAT NAM12 MODEL SNOW DEPTH INITIALIZATION IS
FAR TOO FAR SOUTH...WITH 1 INCH OR MORE OF SNOW DEPTH INTO NORTHERN
MISSOURI. GEM AND RUC ARE CLOSER TO REALITY. GFS MODEL SNOW DEPTH
INITIALIZATION MAY NOT BE ANY BETTER THAN THE NAM12...BUT CANNOT
CHECK ON THAT AT THIS TIME. THUS...HAVE DECIDED TO DEFINITELY ALLOW
THE CLOUDS TO CLEAR OUT OF THE SNOW FREE AREAS ACROSS THE SOUTHERN
HALF TO TWO THIRDS OF THE FORECAST AREA...ALLOWING HIGH TEMPS TO GET
INTO THE MID TO UPPER 50S IN THE AFTERNOON. HOWEVER THE NORTH IS A
WHOLE SEPARATE CAN OF WORMS...WITH THE LOW CLOUDS FOG AND DRIZZLE
HANGING ON INTO THE AFTERNOON AND KEEPING TEMPERATURES IN THE 40S TO
NEAR 50 FOR THE MOST PART. THIS MAKES A LARGE RANGE ACROSS THE
FORECAST AREA IN MAX TEMPS...AND STILL LEAVES US WITH A LARGE BUST
POTENTIAL FOR THIS FORECAST. WITH THIS EXTRAORDINARY WARMTH...THE
RECORD HIGH TEMPERATURE FOR BURLINGTON IS AT RISK...AND WE WILL BE
CLOSE AT OTHER LOCATIONS. FOR REFERENCE...HAVE INCLUDED RECORD HIGHS FOR
FRIDAY BELOW.
OF COURSE...THIS IS NOT THE ONLY CONCERN THIS FORECAST. FRIDAY
NIGHT WILL BE MILD WITH TEMPERATURES REMAINING UP. IN
FACT...LOCATIONS ACROSS THE NORTH THAT DO NOT GET INTO THE SUNSHINE
WILL SLOWLY RISE INTO THE EVENING HOURS AND WILL REACH THEIR HIGH
TEMPERATURES IN THE LATE EVENING TO AROUND MIDNIGHT. THE STRONG
COLD FRONT COMES THROUGH EARLY SATURDAY MORNING AND TEMPERATURES
BEGIN TO FALL...WITH ONLY MINIMAL DIURNAL RISE IN THE AFTERNOON.
SATURDAY NIGHT AND SUNDAY THERE IS A WEAK SHORTWAVE THAT MOVES ALONG
A BAROCLINIC ZONE DRAPED FROM TEXAS UP THE OHIO RIVER VALLEY..WHICH
SHOULD PRODUCE A NICE BAND OF SNOW FOR AREAS NORTHWEST OF THE LOW
TRACK. THE TRICK IS WHETHER THIS SYSTEM WILL SHIFT FAR ENOUGH
NORTHWEST TO BRING SOME ACCUMULATING SNOWS TO THE FORECAST AREA
SATURDAY NIGHT AND EARLY SUNDAY. FOR NOW IT APPEARS THAT THE
SOUTHEAST PORTIONS OF THE AREA WILL GET SOME LIGHT SNOW
ACCUMULATIONS...BUT THE NORTHWEST EDGE OF THIS SNOW BAND WILL BE
FAIRLY SHARP...AND THE QUAD CITIES IS PROBABLY ONLY LOOKING SOME
PRETTY MINOR ACCUMULATIONS...DUSTING TO A HALF INCH PERHAPS.
BEHIND THIS SYSTEM WE ARE LOOKING AT GETTING SOME VERY COLD
TEMPERATURES INTO THE AREA...WITH 850MB TEMPS DROPPING TO AROUND
-10C BY MONDAY MORNING. AS LONG AS WE CLEAR OFF...TEMPERATURES WILL
DROP INTO THE TEENS. TEMPERATURES SHOULD SLOWLY MODERATE INTO
WEDNESDAY. ANOTHER LONGWAVE TROUGH IS EXPECTED TO MOVE THROUGH THE
AREA WEDNESDAY...BUT IT IS TOO DRY TO BRING MORE THAN A FRESH SHOT
OF COLDER AIR FOR THURSDAY.
LE
&&
.AVIATION...
VSBYS AND CIGS HAVE COLLAPSED A LITTLE SOONER THAN FORECAST AT
KBRL. A SIMILAR SITUATION WILL OCCUR OVER THE NEXT SEVERAL HOURS
AT KCID/KMLI/KDBQ. LIFR TO VLIFR CONDITIONS WILL BE OCCUR AFT
00Z/11. THE PROBABILITY OF BELOW MINIMUM CONDITIONS AT KCID/KDBQ
HAS INCREASED FROM SEVERAL HOURS AGO. DENSE FOG WITH POTENTIAL
ZERO/ZERO CONDITIONS IS NOW A THREAT FOR KCID/KDBQ. ..08..
&&
.CLIMATE...
CORRECTED THESE RECORD HIGHS.
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY FROM 2 AM TO 10 AM CST FRIDAY FOR BENTON-
BUCHANAN-DELAWARE-DUBUQUE-IOWA-JACKSON-JOHNSON-JONES-LINN.
IL...DENSE FOG ADVISORY FROM 2 AM TO 10 AM CST FRIDAY FOR CARROLL-JO
DAVIESS-STEPHENSON.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1221 PM CST THU JAN 10 2013
.UPDATE...
THE DRY AIR IS STILL WINNING FOR NOW. HOWEVER...BASED ON SFC OBS
AND IMPLIED RADAR THE LEADING EDGE OF PRECIPITATION REACHING THE
GROUND APPEARS TO BE ALIGNED WITH CONDENSATION PRESSURE DEFICITS
BELOW 50 IN THE 1000-850MB LAYER AND PWAT OF 1.10 PER RAP TRENDS.
ASSUMING THAT THIS TREND WILL CONTINUE...THEN THE LEADING EDGE OF
THE PRECIPITATION WOULD BE NO FURTHER NORTH THAN THE HWY 30
CORRIDOR BY MID AFTERNOON. THE RAP TRENDS HAVE BEEN FAIRLY
CONSISTENT IN INDICATING THAT A SIGNIFICANT SURGE OF MOISTURE FROM
MID TO LATE AFTERNOON WILL RESULT IN RAPID TOP DOWN SATURATION
WITH PRECIPITATION OCCURRING ACROSS THE ENTIRE CWFA BY THE EVENING
COMMUTE. AN UPDATE REFLECTING THESE TRENDS WILL BE AVAILABLE
SHORTLY. ..08..
&&
.PREV DISCUSSION... /ISSUED 1135 AM CST THU JAN 10 2013/
AVIATION...
THE INITIALLY DRY ATMOSPHERE WILL SATURATE THROUGH 00Z/11 ALLOWING
PRECIPITATION TO DEVELOP. THIS SATURATION WILL RESULT IN VFR
CONDITIONS RAPIDLY DETERIORATING TO IFR WITH LIFR OR VLIFR
CONDITIONS DVLPG AFT 00Z/11. THE MOISTURE SURGING INTO THE AREA
OVER A SNOW FIELD DOES BRING THE POSSIBILITY OF BELOW MINIMUMS
DEVELOPING AT KCID/KDBQ. AN INVERSION IS EXPECTED TO TRAP MOISTURE
FOR MUCH OF THE DAYLIGHT HOURS AFT 12Z/11 WHICH SHOULD RESULT IN
LIFR CONDITIONS CONTINUING. ..08..
PREV DISCUSSION... /ISSUED 957 AM CST THU JAN 10 2013/
UPDATE...
AN UPDATE HAS BEEN DONE TO REFLECT CURRENT TRENDS.
12Z SOUNDING SHOWS THE DRY AIR OVER THE AREA IS CONSIDERABLE. SAID
DRY AIR IS HAVING THE EXPECTED IMPACT ON PRECIPITATION GENERATION
AND OVERALL TIMING INTO THE AREA. WHERE IT IS RAINING ON THE
LEADING EDGE IT IS FALLING OUT OF MID LEVEL CLOUDS AROUND 10KFT
AGL AND IS LIKELY MORE SPRINKLES THAN RAIN.
TOP DOWN SATURATION IS NON-LINEAR BY NATURE AND NOT HANDLED BY THE
MODELS. EACH SITUATION IS DIFFERENT AND THE SATURATION CAN OCCUR
FASTER/SLOWER THAN EXPECTED.
A COMBINATION OF RAP TRENDS USING CONDENSATION PRESSURE
DEFICITS/FORCING ALONG WITH THE HEAVY RAIN TOOL SUGGEST SPRINKLES
OR VERY LIGHT RAIN MAY REACH A KGGI TO KGBG LINE BY MID DAY WITH
THE BETTER RAIN JUST GETTING INTO THE EXTREME SOUTH.
DURING THE AFTERNOON HOURS A MORE SIGNIFICANT SLUG OF MOISTURE
BEGINS MOVING TOWARD THE AREA.
BY MID AFTERNOON SPRINKLES OR VERY LIGHT RAIN SHOULD BE AS FAR
NORTH AS A KALO/KOLZ TO ROUGHLY KRPJ LINE. THE IMMEDIATE HWY 20
CORRIDOR FROM DUBUQUE EAST SHOULD STILL BE DRY BUT WITH RAIN
ENCROACHING ON THE AREA.
IF THE RAP TRENDS ARE CORRECT...SATURATION IS RAPIDLY ACHIEVED
ACROSS THE NORTHERN CWFA DURING THE LATE AFTERNOON HOURS. RAIN
SHOULD BE FALLING ACROSS THE ENTIRE AREA DURING THE EVENING COMMUTE.
THE DRY AIR WILL ALSO RESULT IN EVAPORATIVE COOLING WHICH MAY
SUPPRESS TEMPERATURES DURING THE DAY. LIKE YESTERDAY...THE HIGH
FOR THE VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME
FRAME. THE HIGH FOR THE CLIMATE DAY OF JAN 10TH WILL LIKELY OCCUR
BETWEEN 8 PM AND MIDNIGHT. ..08..
PREV DISCUSSION... /ISSUED 337 AM CST THU JAN 10 2013/
SYNOPSIS...
CLOSED UPPER LOW WAS LOCATED OVER WEST TX AND HAS RECENTLY BEGUN
LIFTING NORTH IN RESPONSE TO ENERGY MOVING ONSHORE WEST COAST.
RAIN SHIELD ATTENDANT TO TX LOW ALSO LIFTING NORTH WITH TWO MAIN
AREAS... ONE OVER KS/OK/NW TX JUST NORTH OF MAIN CIRCULATION IN
ZONE OF STRONG ELEVATED MOISTURE TRANSPORT... AND THE OTHER MORE
LINEAR EXTENDING FROM TX/LA GULF COAST TO JUST S/E OF ST LOUIS
IN A SECONDARY BRANCH OF MOISTURE ADVECTION AND INCREASINGLY
DIFFLUENT FLOW ALOFT. 00Z RAOBS TO OUR SOUTH SHOW SIGNIFICANT
AMOUNTS OF MOISTURE WITH PRECIPITABLE WATER VALUES AT KOUN...
KLZK...KFWD AND KJAN RANGING FROM NEARLY 1.25 INCHES TO 1.4 INCHES
WHICH IS AROUND 250 TO NEARLY 350 PERCENT OF NORMAL.
SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS WITH INCOMING RAIN AND AMOUNTS... AND TEMPS. SHORT RANGE
MODELS IN PRETTY GOOD AGREEMENT ON CLOSED TX LOW LIFTING NEGATIVELY
TILTED THROUGH THE MID MISSISSIPPI VALLEY TONIGHT...PASSING NEAR TO
JUST SOUTH OF CWA. RAIN WILL OVERSPREAD THE CWA FROM SOUTH TO NORTH
TODAY AND INITIALLY BE MAINLY LIGHT. RAIN INTENSITY TO INCREASE
LATER TODAY (MAINLY SOUTH) AND ESPECIALLY THIS EVE TO JUST BEYOND
06Z WITH MAIN BOUT OF FORCING. BY THIS TIME... SIGNIFICANT MOISTURE
WILL BE IN PLACE WITH GEFS DEPICTING PRECIPITABLE WATER VALUES AT
LEAST 4 TO 5 STANDARD DEVIATIONS ABOVE NORMAL AND GENERALLY RANGING
FROM 1 TO 1.25 INCHES. THUS... SYSTEM WILL BE VERY WET WITH
WIDESPREAD 0.3 TO 0.75 INCH RAIN AMOUNTS THROUGH 12Z... WITH SOME
AREAS OF 1-1.5 INCHES ESPECIALLY JUST NW OF MAIN CENTER OF CIRCULATION
WITH ALONG AND S/E OF KIOW-KFEP LINE MOST LIKELY PORTION OF CWA TO
SEE SOME OF THESE HIGHER AMOUNTS FROM THE LOOKS OF THINGS ATTIM.
RAIN TAPER OFF IN INTENSITY AND AMOUNTS OVERNIGHT BUT ABUNDANT LOW
LEVEL MOISTURE AND LIFT SUPPORTIVE OF LIGHT RAIN AND DRIZZLE. SOME
AREAS OF FOG ALSO LIKELY TONIGHT AS SFC LOW MOVES ACROSS THE CWA.
AS FOR TEMPS... MANY AREAS LIKELY WILL SEE DAILY HIGHS OCCUR LATER
THIS EVE AS TEMPS CONTINUE TO CLIMB THROUGH ADVECTIVE PROCESSES.
WITH E/SE WINDS... CLOUDS AND RAIN OVERSPREADING AREA TODAY I STAYED
TOWARD THE COOLER SIDE OF GUIDANCE FOR TEMPS. I ALLOWED FOR A LITTLE
DROP OFF EARLY THIS EVE BEFORE TEMPS RISE. MCCLURE
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
WARM SECTOR OF THE SURFACE CYCLONE PASSING WELL TO THE NORTHWEST
WILL SWEEP THROUGH THE AREA FRIDAY...RESULTING IN A POTENTIAL FOR
RECORD HIGH TEMPERATURES. TRAILING COLD FRONT WILL BRING MUCH COLDER
WEATHER THAT WILL PREVAIL THROUGH WEEKEND INTO NEXT WEEK. AN UPPER
LEVEL SYSTEM IS STILL ON TRACK TO BRING THE POTENTIAL FOR LIGHT SNOW
ACROSS MAINLY THE SOUTHEAST SATURDAY NIGHT INTO EARLY SUNDAY.
CHALLENGE FOR FRIDAY WILL BE WHETHER THE DEVELOPING SOUTHERLY WINDS
AND WARM ADVECTION CAN BREAK THROUGH THE MOIST LOW LEVEL INVERSION
AND STRATUS UNDER THE STRONGER ELEVATED WARM ADVECTION AND INFLUX OF
MUCH DRIER AIR ABOVE 900 MB. MODEL FORECAST SOUNDINGS OFFER A WIDE
RANGE OF SOLUTIONS...WITH THE NAM MOST PESSIMISTIC SUGGESTING LOW CLOUDS
AND POSSIBLE FOG HANGING ON THROUGH THE DAY WITH MUCH COOLER
TEMPERATURES...LIKELY DUE TO THE MODEL/S OVERDONE DEPICTION OF
LINGERING SNOW COVER. FOR NOW...WILL GO WITH A COMPROMISE CLOSER TO
A BLEND OF GFS AND ECMWF LOW LEVEL THERMAL FIELDS. THIS WOULD RESULT
IN AT LEAST PARTIAL CLEARING OF STRATUS INTO THE FAR SOUTH DURING
THE AFTERNOON ON 10 TO 15 KT SOUTHERLY SURFACE WINDS. FURTHER
NORTH...THE STRATUS WILL TAKE LONGER TO CLEAR IN THE SLIGHTLY WEAKER
SOUTH WINDS OVER THE COLDER GROUND AND PATCHES OF SNOW. THIS IMPACT
WILL BE GREATEST NORTH OF THE HIGHWAY 30 CORRIDOR WHERE AT LEAST
PATCHES OF OLD SNOW AND ICE SHOULD REMAIN. WILL GO WITH A MENTION OF
FOG AND DRIZZLE THERE FOR MUCH OF THE DAY...WHILE ANY FOG/HAZE OVER
THE CENTRAL AND SOUTH SHOULD DROP BELOW THRESHOLDS FOR MENTION IN
THE PUBLIC FORECAST BY LATE MORNING. OVERALL CONFIDENCE REMAINS
BELOW AVERAGE IN THE POTENTIAL FOR CLEARING AND THE DEPTH OF
MIXING...OVER ESPECIALLY THE CENTRAL AND NORTH AND WILL KEEP HIGHS
LIMITED TO THE MID 40S TO AROUND 50 NORTH OF I-80...WHILE THE FAR
SOUTH HAS A GOOD POTENTIAL TO BREAKOUT AND WARM INTO THE MID AND
UPPER 50S. THIS MAY THREATEN RECORD HIGHS SET LAST YEAR...ESPECIALLY
AT BRL. THESE ARE LISTED IN THE CLIMATE SECTION BELOW.
WILL CONTINUE WITH SLIGHTLY FASTER TIMING SHOWN BY NON-GFS MODEL
CONSENSUS...SWEEPING THE COLD FRONT THROUGH THE FORECAST AREA
FRIDAY NIGHT AND EXITING TO THE EAST BY SUNRISE SATURDAY. THIS
WILL RESULT IN CONTINUED NON-DIURNAL TEMPERATURE TRENDS FRIDAY NIGHT
INTO SATURDAY...WHERE TEMPERATURES SHOULD START FROM THE 30S NW TO
UPPER 40S SE EARLY...DROPPING TO THE 20S AND 30S BY LATE SATURDAY
AFTERNOON WITH COLD ADVECTION ON BRISK WEST WINDS. WITH VERY LITTLE
LOW OR MID LEVEL MOISTURE...NO PRECIPITATION IS EXPECTED WITH THE
FROPA OR IN THE SUBSIDENCE THAT FOLLOWS SATURDAY.
SATURDAY NIGHT...THE UPPER TROUGH AXIS REMAINS WELL TO THE WEST
KEEPING A FAST SW FLOW ALOFT OVER THE AREA. AN EMBEDDED SHORTWAVE
AND RIGHT ENTRANCE REGION TO A STRONG UPPER JET MOVING THROUGH THE
UPPER GREAT LAKES WILL SEND A WAVE OF LIFT OVER THE SOUTHEAST THIRD
OF THE FORECAST AREA. WHILE MOISTURE WILL BE LIMITED...CHANCE POPS
FOR LIGHT SNOW ARE JUSTIFIED FOR ESPECIALLY W CENTRAL IL. THE GFS
AND ECMWF THERMAL FIELDS WOULD SUPPORT A POSSIBILITY FOR MIXED
PRECIPITATION AT THE ONSET...WHICH WILL BE LEFT FOR CONSIDERATION IN
LATER FORECASTS. OTHERWISE...COLD ADVECTION WILL CONTINUE
WITH TEMPERATURES DROPPING INTO THE TEENS BY SUNDAY MORNING OVER THE
AREA.
SUNDAY THROUGH WEDNESDAY...COLD HIGH PRESSURE WILL RESULT IN BELOW
NORMAL TEMPERATURES SUNDAY AND MONDAY. A DEVELOPING UPPER LOW OVER
THE HUDSON BAY REGION WILL THEN PLACE A CYCLONIC NW FLOW OVERHEAD
TUE THROUGH WED. THE ACTIVE STORM TRACK STAYING NORTH OF THE
AREA...ALONG WITH GRADUAL MODERATION OF TEMPERATURES
ALOFT...SUGGESTS A PERIOD OF DRY WEATHER WITH SLIGHTLY WARMER
TEMPERATURES BY MID WEEK.
SHEETS
CLIMATE...
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1135 AM CST THU JAN 10 2013
.AVIATION...
THE INITIALLY DRY ATMOSPHERE WILL SATURATE THROUGH 00Z/11 ALLOWING
PRECIPITATION TO DEVELOP. THIS SATURATION WILL RESULT IN VFR
CONDITIONS RAPIDLY DETERIORATING TO IFR WITH LIFR OR VLIFR
CONDITIONS DVLPG AFT 00Z/11. THE MOISTURE SURGING INTO THE AREA
OVER A SNOW FIELD DOES BRING THE POSSIBILITY OF BELOW MINIMUMS
DEVELOPING AT KCID/KDBQ. AN INVERSION IS EXPECTED TO TRAP MOISTURE
FOR MUCH OF THE DAYLIGHT HOURS AFT 12Z/11 WHICH SHOULD RESULT IN
LIFR CONDITIONS CONTINUING. ..08..
&&
.PREV DISCUSSION... /ISSUED 957 AM CST THU JAN 10 2013/
UPDATE...
AN UPDATE HAS BEEN DONE TO REFLECT CURRENT TRENDS.
12Z SOUNDING SHOWS THE DRY AIR OVER THE AREA IS CONSIDERABLE. SAID
DRY AIR IS HAVING THE EXPECTED IMPACT ON PRECIPITATION GENERATION
AND OVERALL TIMING INTO THE AREA. WHERE IT IS RAINING ON THE
LEADING EDGE IT IS FALLING OUT OF MID LEVEL CLOUDS AROUND 10KFT
AGL AND IS LIKELY MORE SPRINKLES THAN RAIN.
TOP DOWN SATURATION IS NON-LINEAR BY NATURE AND NOT HANDLED BY THE
MODELS. EACH SITUATION IS DIFFERENT AND THE SATURATION CAN OCCUR
FASTER/SLOWER THAN EXPECTED.
A COMBINATION OF RAP TRENDS USING CONDENSATION PRESSURE
DEFICITS/FORCING ALONG WITH THE HEAVY RAIN TOOL SUGGEST SPRINKLES
OR VERY LIGHT RAIN MAY REACH A KGGI TO KGBG LINE BY MID DAY WITH
THE BETTER RAIN JUST GETTING INTO THE EXTREME SOUTH.
DURING THE AFTERNOON HOURS A MORE SIGNIFICANT SLUG OF MOISTURE
BEGINS MOVING TOWARD THE AREA.
BY MID AFTERNOON SPRINKLES OR VERY LIGHT RAIN SHOULD BE AS FAR
NORTH AS A KALO/KOLZ TO ROUGHLY KRPJ LINE. THE IMMEDIATE HWY 20
CORRIDOR FROM DUBUQUE EAST SHOULD STILL BE DRY BUT WITH RAIN
ENCROACHING ON THE AREA.
IF THE RAP TRENDS ARE CORRECT...SATURATION IS RAPIDLY ACHIEVED
ACROSS THE NORTHERN CWFA DURING THE LATE AFTERNOON HOURS. RAIN
SHOULD BE FALLING ACROSS THE ENTIRE AREA DURING THE EVENING COMMUTE.
THE DRY AIR WILL ALSO RESULT IN EVAPORATIVE COOLING WHICH MAY
SUPPRESS TEMPERATURES DURING THE DAY. LIKE YESTERDAY...THE HIGH
FOR THE VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME
FRAME. THE HIGH FOR THE CLIMATE DAY OF JAN 10TH WILL LIKELY OCCUR
BETWEEN 8 PM AND MIDNIGHT. ..08..
PREV DISCUSSION... /ISSUED 337 AM CST THU JAN 10 2013/
SYNOPSIS...
CLOSED UPPER LOW WAS LOCATED OVER WEST TX AND HAS RECENTLY BEGUN
LIFTING NORTH IN RESPONSE TO ENERGY MOVING ONSHORE WEST COAST.
RAIN SHIELD ATTENDANT TO TX LOW ALSO LIFTING NORTH WITH TWO MAIN
AREAS... ONE OVER KS/OK/NW TX JUST NORTH OF MAIN CIRCULATION IN
ZONE OF STRONG ELEVATED MOISTURE TRANSPORT... AND THE OTHER MORE
LINEAR EXTENDING FROM TX/LA GULF COAST TO JUST S/E OF ST LOUIS
IN A SECONDARY BRANCH OF MOISTURE ADVECTION AND INCREASINGLY
DIFFLUENT FLOW ALOFT. 00Z RAOBS TO OUR SOUTH SHOW SIGNIFICANT
AMOUNTS OF MOISTURE WITH PRECIPITABLE WATER VALUES AT KOUN...
KLZK...KFWD AND KJAN RANGING FROM NEARLY 1.25 INCHES TO 1.4 INCHES
WHICH IS AROUND 250 TO NEARLY 350 PERCENT OF NORMAL.
SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS WITH INCOMING RAIN AND AMOUNTS... AND TEMPS. SHORT RANGE
MODELS IN PRETTY GOOD AGREEMENT ON CLOSED TX LOW LIFTING NEGATIVELY
TILTED THROUGH THE MID MISSISSIPPI VALLEY TONIGHT...PASSING NEAR TO
JUST SOUTH OF CWA. RAIN WILL OVERSPREAD THE CWA FROM SOUTH TO NORTH
TODAY AND INITIALLY BE MAINLY LIGHT. RAIN INTENSITY TO INCREASE
LATER TODAY (MAINLY SOUTH) AND ESPECIALLY THIS EVE TO JUST BEYOND
06Z WITH MAIN BOUT OF FORCING. BY THIS TIME... SIGNIFICANT MOISTURE
WILL BE IN PLACE WITH GEFS DEPICTING PRECIPITABLE WATER VALUES AT
LEAST 4 TO 5 STANDARD DEVIATIONS ABOVE NORMAL AND GENERALLY RANGING
FROM 1 TO 1.25 INCHES. THUS... SYSTEM WILL BE VERY WET WITH
WIDESPREAD 0.3 TO 0.75 INCH RAIN AMOUNTS THROUGH 12Z... WITH SOME
AREAS OF 1-1.5 INCHES ESPECIALLY JUST NW OF MAIN CENTER OF CIRCULATION
WITH ALONG AND S/E OF KIOW-KFEP LINE MOST LIKELY PORTION OF CWA TO
SEE SOME OF THESE HIGHER AMOUNTS FROM THE LOOKS OF THINGS ATTIM.
RAIN TAPER OFF IN INTENSITY AND AMOUNTS OVERNIGHT BUT ABUNDANT LOW
LEVEL MOISTURE AND LIFT SUPPORTIVE OF LIGHT RAIN AND DRIZZLE. SOME
AREAS OF FOG ALSO LIKELY TONIGHT AS SFC LOW MOVES ACROSS THE CWA.
AS FOR TEMPS... MANY AREAS LIKELY WILL SEE DAILY HIGHS OCCUR LATER
THIS EVE AS TEMPS CONTINUE TO CLIMB THROUGH ADVECTIVE PROCESSES.
WITH E/SE WINDS... CLOUDS AND RAIN OVERSPREADING AREA TODAY I STAYED
TOWARD THE COOLER SIDE OF GUIDANCE FOR TEMPS. I ALLOWED FOR A LITTLE
DROP OFF EARLY THIS EVE BEFORE TEMPS RISE. MCCLURE
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
WARM SECTOR OF THE SURFACE CYCLONE PASSING WELL TO THE NORTHWEST
WILL SWEEP THROUGH THE AREA FRIDAY...RESULTING IN A POTENTIAL FOR
RECORD HIGH TEMPERATURES. TRAILING COLD FRONT WILL BRING MUCH COLDER
WEATHER THAT WILL PREVAIL THROUGH WEEKEND INTO NEXT WEEK. AN UPPER
LEVEL SYSTEM IS STILL ON TRACK TO BRING THE POTENTIAL FOR LIGHT SNOW
ACROSS MAINLY THE SOUTHEAST SATURDAY NIGHT INTO EARLY SUNDAY.
CHALLENGE FOR FRIDAY WILL BE WHETHER THE DEVELOPING SOUTHERLY WINDS
AND WARM ADVECTION CAN BREAK THROUGH THE MOIST LOW LEVEL INVERSION
AND STRATUS UNDER THE STRONGER ELEVATED WARM ADVECTION AND INFLUX OF
MUCH DRIER AIR ABOVE 900 MB. MODEL FORECAST SOUNDINGS OFFER A WIDE
RANGE OF SOLUTIONS...WITH THE NAM MOST PESSIMISTIC SUGGESTING LOW CLOUDS
AND POSSIBLE FOG HANGING ON THROUGH THE DAY WITH MUCH COOLER
TEMPERATURES...LIKELY DUE TO THE MODEL/S OVERDONE DEPICTION OF
LINGERING SNOW COVER. FOR NOW...WILL GO WITH A COMPROMISE CLOSER TO
A BLEND OF GFS AND ECMWF LOW LEVEL THERMAL FIELDS. THIS WOULD RESULT
IN AT LEAST PARTIAL CLEARING OF STRATUS INTO THE FAR SOUTH DURING
THE AFTERNOON ON 10 TO 15 KT SOUTHERLY SURFACE WINDS. FURTHER
NORTH...THE STRATUS WILL TAKE LONGER TO CLEAR IN THE SLIGHTLY WEAKER
SOUTH WINDS OVER THE COLDER GROUND AND PATCHES OF SNOW. THIS IMPACT
WILL BE GREATEST NORTH OF THE HIGHWAY 30 CORRIDOR WHERE AT LEAST
PATCHES OF OLD SNOW AND ICE SHOULD REMAIN. WILL GO WITH A MENTION OF
FOG AND DRIZZLE THERE FOR MUCH OF THE DAY...WHILE ANY FOG/HAZE OVER
THE CENTRAL AND SOUTH SHOULD DROP BELOW THRESHOLDS FOR MENTION IN
THE PUBLIC FORECAST BY LATE MORNING. OVERALL CONFIDENCE REMAINS
BELOW AVERAGE IN THE POTENTIAL FOR CLEARING AND THE DEPTH OF
MIXING...OVER ESPECIALLY THE CENTRAL AND NORTH AND WILL KEEP HIGHS
LIMITED TO THE MID 40S TO AROUND 50 NORTH OF I-80...WHILE THE FAR
SOUTH HAS A GOOD POTENTIAL TO BREAKOUT AND WARM INTO THE MID AND
UPPER 50S. THIS MAY THREATEN RECORD HIGHS SET LAST YEAR...ESPECIALLY
AT BRL. THESE ARE LISTED IN THE CLIMATE SECTION BELOW.
WILL CONTINUE WITH SLIGHTLY FASTER TIMING SHOWN BY NON-GFS MODEL
CONSENSUS...SWEEPING THE COLD FRONT THROUGH THE FORECAST AREA
FRIDAY NIGHT AND EXITING TO THE EAST BY SUNRISE SATURDAY. THIS
WILL RESULT IN CONTINUED NON-DIURNAL TEMPERATURE TRENDS FRIDAY NIGHT
INTO SATURDAY...WHERE TEMPERATURES SHOULD START FROM THE 30S NW TO
UPPER 40S SE EARLY...DROPPING TO THE 20S AND 30S BY LATE SATURDAY
AFTERNOON WITH COLD ADVECTION ON BRISK WEST WINDS. WITH VERY LITTLE
LOW OR MID LEVEL MOISTURE...NO PRECIPITATION IS EXPECTED WITH THE
FROPA OR IN THE SUBSIDENCE THAT FOLLOWS SATURDAY.
SATURDAY NIGHT...THE UPPER TROUGH AXIS REMAINS WELL TO THE WEST
KEEPING A FAST SW FLOW ALOFT OVER THE AREA. AN EMBEDDED SHORTWAVE
AND RIGHT ENTRANCE REGION TO A STRONG UPPER JET MOVING THROUGH THE
UPPER GREAT LAKES WILL SEND A WAVE OF LIFT OVER THE SOUTHEAST THIRD
OF THE FORECAST AREA. WHILE MOISTURE WILL BE LIMITED...CHANCE POPS
FOR LIGHT SNOW ARE JUSTIFIED FOR ESPECIALLY W CENTRAL IL. THE GFS
AND ECMWF THERMAL FIELDS WOULD SUPPORT A POSSIBILITY FOR MIXED
PRECIPITATION AT THE ONSET...WHICH WILL BE LEFT FOR CONSIDERATION IN
LATER FORECASTS. OTHERWISE...COLD ADVECTION WILL CONTINUE
WITH TEMPERATURES DROPPING INTO THE TEENS BY SUNDAY MORNING OVER THE
AREA.
SUNDAY THROUGH WEDNESDAY...COLD HIGH PRESSURE WILL RESULT IN BELOW
NORMAL TEMPERATURES SUNDAY AND MONDAY. A DEVELOPING UPPER LOW OVER
THE HUDSON BAY REGION WILL THEN PLACE A CYCLONIC NW FLOW OVERHEAD
TUE THROUGH WED. THE ACTIVE STORM TRACK STAYING NORTH OF THE
AREA...ALONG WITH GRADUAL MODERATION OF TEMPERATURES
ALOFT...SUGGESTS A PERIOD OF DRY WEATHER WITH SLIGHTLY WARMER
TEMPERATURES BY MID WEEK.
SHEETS
CLIMATE...
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
957 AM CST THU JAN 10 2013
.UPDATE...
AN UPDATE HAS BEEN DONE TO REFLECT CURRENT TRENDS.
12Z SOUNDING SHOWS THE DRY AIR OVER THE AREA IS CONSIDERABLE. SAID
DRY AIR IS HAVING THE EXPECTED IMPACT ON PRECIPITATION GENERATION
AND OVERALL TIMING INTO THE AREA. WHERE IT IS RAINING ON THE
LEADING EDGE IT IS FALLING OUT OF MID LEVEL CLOUDS AROUND 10KFT
AGL AND IS LIKELY MORE SPRINKLES THAN RAIN.
TOP DOWN SATURATION IS NON-LINEAR BY NATURE AND NOT HANDLED BY THE
MODELS. EACH SITUATION IS DIFFERENT AND THE SATURATION CAN OCCUR
FASTER/SLOWER THAN EXPECTED.
A COMBINATION OF RAP TRENDS USING CONDENSATION PRESSURE
DEFICITS/FORCING ALONG WITH THE HEAVY RAIN TOOL SUGGEST SPRINKLES
OR VERY LIGHT RAIN MAY REACH A KGGI TO KGBG LINE BY MID DAY WITH
THE BETTER RAIN JUST GETTING INTO THE EXTREME SOUTH.
DURING THE AFTERNOON HOURS A MORE SIGNIFICANT SLUG OF MOISTURE
BEGINS MOVING TOWARD THE AREA.
BY MID AFTERNOON SPRINKLES OR VERY LIGHT RAIN SHOULD BE AS FAR
NORTH AS A KALO/KOLZ TO ROUGHLY KRPJ LINE. THE IMMEDIATE HWY 20
CORRIDOR FROM DUBUQUE EAST SHOULD STILL BE DRY BUT WITH RAIN
ENCROACHING ON THE AREA.
IF THE RAP TRENDS ARE CORRECT...SATURATION IS RAPIDLY ACHIEVED
ACROSS THE NORTHERN CWFA DURING THE LATE AFTERNOON HOURS. RAIN
SHOULD BE FALLING ACROSS THE ENTIRE AREA DURING THE EVENING COMMUTE.
THE DRY AIR WILL ALSO RESULT IN EVAPORATIVE COOLING WHICH MAY
SUPPRESS TEMPERATURES DURING THE DAY. LIKE YESTERDAY...THE HIGH
FOR THE VERIFYING PERIOD WILL LIKELY OCCUR IN THE 6-8 PM TIME
FRAME. THE HIGH FOR THE CLIMATE DAY OF JAN 10TH WILL LIKELY OCCUR
BETWEEN 8 PM AND MIDNIGHT. ..08..
&&
.PREV DISCUSSION... /ISSUED 600 AM CST THU JAN 10 2013/
AVIATION...
VFR CONDITIONS WILL CONTINUE TO BE SEEN THROUGH 15Z THEN BANDS OF
LIGHT TO MODERATE RAIN WILL ARRIVE AT THE TERMINALS FROM NORTH
TO SOUTH FROM 16Z TO 22Z... AS A STORM SYSTEM APPROACHES FROM THE
SOUTHERN PLAINS. CONDITIONS TO DETERIORATE TO IFR AND POSSIBLY
LIFR WITHIN 2 TO 3 HRS OF THE RAIN STARTING. EXPECT WIDESPREAD
IFR TO LIFR CONDITIONS TONIGHT WITH PERIODS OF RAIN AND
DRIZZLE... WITH POSSIBLY VLIFR CONDITIONS IN DENSE FOG DEPENDING
ON THE TRACK OF THE SFC LOW. WINDS WILL MAINLY BE OUT OF THE E/SE
AT 4-12 KTS FOR MUCH OF THE TAF CYCLE... BUT BEGIN TO TURN MORE
S/SWLY TOWARD 12Z FRI IN WAKE OF PASSING SYSTEM.
PREV DISCUSSION... /ISSUED 337 AM CST THU JAN 10 2013/
SYNOPSIS...
CLOSED UPPER LOW WAS LOCATED OVER WEST TX AND HAS RECENTLY BEGUN
LIFTING NORTH IN RESPONSE TO ENERGY MOVING ONSHORE WEST COAST.
RAIN SHIELD ATTENDANT TO TX LOW ALSO LIFTING NORTH WITH TWO MAIN
AREAS... ONE OVER KS/OK/NW TX JUST NORTH OF MAIN CIRCULATION IN
ZONE OF STRONG ELEVATED MOISTURE TRANSPORT... AND THE OTHER MORE
LINEAR EXTENDING FROM TX/LA GULF COAST TO JUST S/E OF ST LOUIS
IN A SECONDARY BRANCH OF MOISTURE ADVECTION AND INCREASINGLY
DIFFLUENT FLOW ALOFT. 00Z RAOBS TO OUR SOUTH SHOW SIGNIFICANT
AMOUNTS OF MOISTURE WITH PRECIPITABLE WATER VALUES AT KOUN...
KLZK...KFWD AND KJAN RANGING FROM NEARLY 1.25 INCHES TO 1.4 INCHES
WHICH IS AROUND 250 TO NEARLY 350 PERCENT OF NORMAL.
SHORT TERM...TODAY AND TONIGHT...
MAIN FOCUS WITH INCOMING RAIN AND AMOUNTS... AND TEMPS. SHORT RANGE
MODELS IN PRETTY GOOD AGREEMENT ON CLOSED TX LOW LIFTING NEGATIVELY
TILTED THROUGH THE MID MISSISSIPPI VALLEY TONIGHT...PASSING NEAR TO
JUST SOUTH OF CWA. RAIN WILL OVERSPREAD THE CWA FROM SOUTH TO NORTH
TODAY AND INITIALLY BE MAINLY LIGHT. RAIN INTENSITY TO INCREASE
LATER TODAY (MAINLY SOUTH) AND ESPECIALLY THIS EVE TO JUST BEYOND
06Z WITH MAIN BOUT OF FORCING. BY THIS TIME... SIGNIFICANT MOISTURE
WILL BE IN PLACE WITH GEFS DEPICTING PRECIPITABLE WATER VALUES AT
LEAST 4 TO 5 STANDARD DEVIATIONS ABOVE NORMAL AND GENERALLY RANGING
FROM 1 TO 1.25 INCHES. THUS... SYSTEM WILL BE VERY WET WITH
WIDESPREAD 0.3 TO 0.75 INCH RAIN AMOUNTS THROUGH 12Z... WITH SOME
AREAS OF 1-1.5 INCHES ESPECIALLY JUST NW OF MAIN CENTER OF CIRCULATION
WITH ALONG AND S/E OF KIOW-KFEP LINE MOST LIKELY PORTION OF CWA TO
SEE SOME OF THESE HIGHER AMOUNTS FROM THE LOOKS OF THINGS ATTIM.
RAIN TAPER OFF IN INTENSITY AND AMOUNTS OVERNIGHT BUT ABUNDANT LOW
LEVEL MOISTURE AND LIFT SUPPORTIVE OF LIGHT RAIN AND DRIZZLE. SOME
AREAS OF FOG ALSO LIKELY TONIGHT AS SFC LOW MOVES ACROSS THE CWA.
AS FOR TEMPS... MANY AREAS LIKELY WILL SEE DAILY HIGHS OCCUR LATER
THIS EVE AS TEMPS CONTINUE TO CLIMB THROUGH ADVECTIVE PROCESSES.
WITH E/SE WINDS... CLOUDS AND RAIN OVERSPREADING AREA TODAY I STAYED
TOWARD THE COOLER SIDE OF GUIDANCE FOR TEMPS. I ALLOWED FOR A LITTLE
DROP OFF EARLY THIS EVE BEFORE TEMPS RISE. MCCLURE
LONG TERM...FRIDAY THROUGH NEXT WEDNESDAY...
WARM SECTOR OF THE SURFACE CYCLONE PASSING WELL TO THE NORTHWEST
WILL SWEEP THROUGH THE AREA FRIDAY...RESULTING IN A POTENTIAL FOR
RECORD HIGH TEMPERATURES. TRAILING COLD FRONT WILL BRING MUCH COLDER
WEATHER THAT WILL PREVAIL THROUGH WEEKEND INTO NEXT WEEK. AN UPPER
LEVEL SYSTEM IS STILL ON TRACK TO BRING THE POTENTIAL FOR LIGHT SNOW
ACROSS MAINLY THE SOUTHEAST SATURDAY NIGHT INTO EARLY SUNDAY.
CHALLENGE FOR FRIDAY WILL BE WHETHER THE DEVELOPING SOUTHERLY WINDS
AND WARM ADVECTION CAN BREAK THROUGH THE MOIST LOW LEVEL INVERSION
AND STRATUS UNDER THE STRONGER ELEVATED WARM ADVECTION AND INFLUX OF
MUCH DRIER AIR ABOVE 900 MB. MODEL FORECAST SOUNDINGS OFFER A WIDE
RANGE OF SOLUTIONS...WITH THE NAM MOST PESSIMISTIC SUGGESTING LOW CLOUDS
AND POSSIBLE FOG HANGING ON THROUGH THE DAY WITH MUCH COOLER
TEMPERATURES...LIKELY DUE TO THE MODEL/S OVERDONE DEPICTION OF
LINGERING SNOW COVER. FOR NOW...WILL GO WITH A COMPROMISE CLOSER TO
A BLEND OF GFS AND ECMWF LOW LEVEL THERMAL FIELDS. THIS WOULD RESULT
IN AT LEAST PARTIAL CLEARING OF STRATUS INTO THE FAR SOUTH DURING
THE AFTERNOON ON 10 TO 15 KT SOUTHERLY SURFACE WINDS. FURTHER
NORTH...THE STRATUS WILL TAKE LONGER TO CLEAR IN THE SLIGHTLY WEAKER
SOUTH WINDS OVER THE COLDER GROUND AND PATCHES OF SNOW. THIS IMPACT
WILL BE GREATEST NORTH OF THE HIGHWAY 30 CORRIDOR WHERE AT LEAST
PATCHES OF OLD SNOW AND ICE SHOULD REMAIN. WILL GO WITH A MENTION OF
FOG AND DRIZZLE THERE FOR MUCH OF THE DAY...WHILE ANY FOG/HAZE OVER
THE CENTRAL AND SOUTH SHOULD DROP BELOW THRESHOLDS FOR MENTION IN
THE PUBLIC FORECAST BY LATE MORNING. OVERALL CONFIDENCE REMAINS
BELOW AVERAGE IN THE POTENTIAL FOR CLEARING AND THE DEPTH OF
MIXING...OVER ESPECIALLY THE CENTRAL AND NORTH AND WILL KEEP HIGHS
LIMITED TO THE MID 40S TO AROUND 50 NORTH OF I-80...WHILE THE FAR
SOUTH HAS A GOOD POTENTIAL TO BREAKOUT AND WARM INTO THE MID AND
UPPER 50S. THIS MAY THREATEN RECORD HIGHS SET LAST YEAR...ESPECIALLY
AT BRL. THESE ARE LISTED IN THE CLIMATE SECTION BELOW.
WILL CONTINUE WITH SLIGHTLY FASTER TIMING SHOWN BY NON-GFS MODEL
CONSENSUS...SWEEPING THE COLD FRONT THROUGH THE FORECAST AREA
FRIDAY NIGHT AND EXITING TO THE EAST BY SUNRISE SATURDAY. THIS
WILL RESULT IN CONTINUED NON-DIURNAL TEMPERATURE TRENDS FRIDAY NIGHT
INTO SATURDAY...WHERE TEMPERATURES SHOULD START FROM THE 30S NW TO
UPPER 40S SE EARLY...DROPPING TO THE 20S AND 30S BY LATE SATURDAY
AFTERNOON WITH COLD ADVECTION ON BRISK WEST WINDS. WITH VERY LITTLE
LOW OR MID LEVEL MOISTURE...NO PRECIPITATION IS EXPECTED WITH THE
FROPA OR IN THE SUBSIDENCE THAT FOLLOWS SATURDAY.
SATURDAY NIGHT...THE UPPER TROUGH AXIS REMAINS WELL TO THE WEST
KEEPING A FAST SW FLOW ALOFT OVER THE AREA. AN EMBEDDED SHORTWAVE
AND RIGHT ENTRANCE REGION TO A STRONG UPPER JET MOVING THROUGH THE
UPPER GREAT LAKES WILL SEND A WAVE OF LIFT OVER THE SOUTHEAST THIRD
OF THE FORECAST AREA. WHILE MOISTURE WILL BE LIMITED...CHANCE POPS
FOR LIGHT SNOW ARE JUSTIFIED FOR ESPECIALLY W CENTRAL IL. THE GFS
AND ECMWF THERMAL FIELDS WOULD SUPPORT A POSSIBILITY FOR MIXED
PRECIPITATION AT THE ONSET...WHICH WILL BE LEFT FOR CONSIDERATION IN
LATER FORECASTS. OTHERWISE...COLD ADVECTION WILL CONTINUE
WITH TEMPERATURES DROPPING INTO THE TEENS BY SUNDAY MORNING OVER THE
AREA.
SUNDAY THROUGH WEDNESDAY...COLD HIGH PRESSURE WILL RESULT IN BELOW
NORMAL TEMPERATURES SUNDAY AND MONDAY. A DEVELOPING UPPER LOW OVER
THE HUDSON BAY REGION WILL THEN PLACE A CYCLONIC NW FLOW OVERHEAD
TUE THROUGH WED. THE ACTIVE STORM TRACK STAYING NORTH OF THE
AREA...ALONG WITH GRADUAL MODERATION OF TEMPERATURES
ALOFT...SUGGESTS A PERIOD OF DRY WEATHER WITH SLIGHTLY WARMER
TEMPERATURES BY MID WEEK.
SHEETS
CLIMATE...
RECORD HIGHS FOR JANUARY 11...
MOLINE.........56 IN 2012
CEDAR RAPIDS...53 IN 2012
DUBUQUE........52 IN 2012
BURLINGTON.....55 IN 2012
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1227 AM EST THU JAN 10 2013
...Updated Aviation Discussion...
.Forecast Update...
Issued 1105 PM EST Wed Jan 9 2013
After consulting with JKL, have gone ahead and upgraded to a Dense
Fog Advisory for our eastern edge for the rest of the night.
Issued 1019 PM EST Wed Jan 9 2013
Social media communications and surface obs show that the fog in the
Blue Grass has become thicker and more dense in spots, so have
introduced patchy dense fog (in addition to the patchy fog already
in the forecast) to our eastern counties. Also went ahead and put
out a SPS for patchy dense fog primarily from Carlisle to Liberty.
Issued at 842 PM EST Wed Jan 9 2013
A few ASOS locations as well as a couple of public reports have
shown that patchy fog has developed across southern and eastern
portions of the CWA. The HRRR actually shows this as well, at least
along the eastern edge of the CWA. Surface analysis shows a
corridor of lower dew point depressions reaching northeastward from
middle Tennessee into eastern Kentucky. Of course we`ve been
concerned with the incoming rain maker, but first, surface high
pressure is still sprawled across the region from the
mid-Mississippi Valley to the Carolinas, keeping winds light. So,
have added patchy fog to the forecast roughly along and southeast of
a Bowling Green-Lexington line. Will let the fog dissipate as rain
moves in and northeast breezes begin to pick up a little later
tonight.
Have also decided to throw in some patchy fog from northern Dubois
County to northern Washington County IN. Dew point depressions are
tightening there and those areas have the added factor of melting
snowcover. A few locations in the Wabash Valley have already
reported some light fog.
In addition, have adjusted the temperatures a bit, especially in the
usual cool spots.
A dense cirrus shield has overspread the region so we have increased
cloud cover to overcast for the rest of the night.
&&
.Short Term (Tonight through Thursday Night)...
Issued at 320 PM EST Wed Jan 9 2013
The weak tail end of a cold front passing mostly over southern
Indiana, northern KY, and locations northeast was located just south
of the Ohio River as of 1945Z. To the southeast of the front, a
thick deck of mid level clouds exists. However, this deck is making
steady progress eastward. Expect skies to go only partly cloudy for
a good portion of this evening before thick, low clouds start to
creep back in from the south after midnight.
After midnight a warm front will approach from the south as part of
a strengthening low pressure system over the OK/TX region. As this
weather system moves northeast to the western Great Lakes by Friday
morning, it will bring us 2 notable rounds of showers/isld storms
late tonight through Friday morning. The first round of elevated
showers/isld storms will come just after midnight tonight and
through tomorrow afternoon as the warm front lifts north through the
area. 6Z/12Z models have been slower with the arrival of these
rains so trended POPs back in time accordingly. We should see a
broad area of light rains slowly move north through the area for
much of Thurs. Any t-storms would likely be elevated north of the
warm front. However, some of the higher res model data suggests a
few scattered cellular structures during the late afternoon/evening
hours Thurs. Still these cells should be of little to no
consequence as morning clouds/rains will rob most areas of heating/
instability. The best chance for any scattered t-storms redeveloping
late Thurs afternoon/evening in the warm sector would be over south
central KY. Total QPF from this first wave of rainfall would be
under a half inch over most locations with areas along and west of
I-65 receiving the most rainfall.
The second wave of rains/isld t-storms will be late Thurs night into
Friday morning with the passage of a cold front. Before then, we
may continue to see scattered rains across the area Thurs evening.
The cold front looks to bring a solid line of rains with embedded
thunder through the area as it will be accompanied by a strong LLJ
(60-70 kts @ h85) and upper level jet support as the potent upper
trough passes just to our northwest. Friday morning would be our
best chance to see some strong to possibly marginally severe storms
due to such a strong LLJ passing through the area. A decent low
level inversion should keep most of the strongest winds aloft.
Still would not be surprise to see 35-50 mph winds mixing down
inside and outside of convection Friday morning. Small hail may
also be possible, but gusty winds and brief heavy rainfall would be
the main threats if any from storms Friday morning.
As far as temps go, they will be tricky over the next 36 hrs as
multiple frontal boundaries push through the area. Lows tonight
will range from the lower 30s over southern Indiana to mid and upper
40s over south central KY as a left over boundary stalls over the
region. Tomorrow expect highs ranging from the upper 40s north to
mid 60s south as we get a warm surge during the afternoon hours.
Thurs night, we`ll likely see a decrease in temps during the evening
hours with lows being reached just after midnight. A warm surge
will occur just ahead of cold front passage Friday morning allowing
temps to warm near dawn. Lows Thurs night should be in the upper
40s to around 60.
.Long Term (Friday through Wednesday)...
Issued at 305 PM EST Wed Jan 9 2013
...Wet and Unsettled Pattern Will Continue...
A building ridge off the Atlantic Coast and a digging western trough
will put the lower half of the Mississippi River Valley and the
entire Ohio River Valley under strong southwest flow aloft. This
will pump in plenty of moisture via an atmospheric river from the
Gulf, and set the stage for a very wet and active long term period.
The cold front associated with our first low pressure system
Thursday night will be entering our western forecast area around
daybreak Friday. Guidance continues to indicate instability will
decrease Thursday night into Friday morning, with some elevated
instability remaining. With the frontal passage at a diurnally
unfavorable time of day, the scenario projected by guidance is
reasonable. So, surfaced-based severe weather is looking less
likely. Surface-based instability will increase a bit through the
day Friday, as high temperatures warm well above normal into the low
and mid 60s. However, shear and large-scale forcing will decrease.
So, will continue with small hail and isolated strong wind gusts
being the main threats.
As this system departs Friday, it will leave behind a stalled
frontal boundary to our northwest that will not move much through
the weekend. Multiple shortwaves will ride over this boundary in
southwest flow aloft, with the first wave of rainfall expected
Saturday afternoon into Sunday. This band of rain should set up
across our northwestern forecast area for the overnight hours. The
rain will diminish a bit Sunday. However, another wave is expected
Sunday afternoon and evening, with yet another wave Sunday night
into Monday. With each wave, the southwest-northeast oriented
rainfall band will slowly track southeast.
Very warm temperatures and near record PWAT for this time
of year will be ushered in from the Gulf, with very high sub-cloud
layer relative humidity and warm cloud depth values in the 10-12Kft
range expected. This sets the stage for high precipitation
efficiency. Area average accumulations of 2-3 inches will be common
from Friday night through the day Monday, with locally higher
amounts possible. With this rain falling on wet ground provided by
the Wednesday and Thursday night/Friday systems, there could be some
areal flooding and rising rivers. Please see the hydrology section
below for more details on river impacts.
The surface front will sag southeast Sunday night, with some cooler
air filtering into our northern forecast area. Probabilistic and
plume data depict a small chance of some mixed precip on the back
side of the system. So, could see some mixed precip late Sunday
night through Monday morning before the system/deep moisture
departs. At this time, do not believe this will cause much of an
impact given the warm ground of late. Will monitor the thermal
profile and deep moisture over the next few model cycles.
As for temperatures, highs Saturday will reach the mid and upper
60s, with a cooling trend expected into Monday as the front slowly
pushes southeast. Highs Monday will range from the mid 30s in the
northwest to around 50 in the southeast. Low temperatures will show
a similar trend, with 40s and 50s Saturday night giving way to 20s
and 30s Monday night.
Guidance differs on the arrival of the next system, but ensemble
data suggests another round of precip Tuesday through Tuesday night.
With the surface boundary projected to be southeast of the forecast
area, cooler air in place across the forecast area, and steady
northeast surface winds, we could see another mixed precip event.
Confidence is not high on the overall thermal profile and placement
of precip, given the differences in model solutions, but ensemble
probabilities suggest a chance of mixed precip. Will continue to
monitor run-to-run model solutions for this system as well. It does
appear the system will exit the area Wednesday, with dry conditions
to follow. High temperatures Tuesday appear to range from mid 30s to
mid 40s, with highs a couple degrees cooler Wednesday. Overnight
lows will trend cooler as well, with generally mid 20s to low 30s
possible by Wednesday night.
&&
.Aviation (06Z TAF Issuance)...
Issued at 1225 AM EST Thu Jan 10 2013
Expect a steady deterioration in ceilings and visibilities from
south to north as a warm front sharpens over Tennessee and lifts
north into Kentucky. The rain shield associated with the front will
lift into BWG over the next couple hours, and into SDF and LEX by
mid-morning.
One complicating factor in LEX is the near-term potential for fog,
as the surface ridge has yet to lose its grip. While visibilities
have really tanked in some of the valley locations, and fog has been
more widespread in east-central Kentucky, believe that there will be
just enough of an easterly wind to close the window on fog there.
Therefore will keep MVFR visibilities until the lower cloud deck
moves in just before daybreak.
Biggest challenge with the rain is just how much conditions will
deteriorate. In general, NAM MOS is much more bullish with IFR
conditions, while GFS MOS barely brings in MVFR. Best chance of IFR
ceilings is in BWG, as we have already seen conditions deteriorate
at BNA and other locations across Tennessee. Will take ceilings down
quickly from 09-12Z, and hold in IFR for much of the day. Diurnal
timing will make it difficult for SDF and LEX to really tank as
advertised by the usually pessimistic NAM. Have generally followed
the timing of the GFS LAMP, but split the difference in conditions
with a few hours of fuel-alternate MVFR.
Warm front will lift north and west of the area, allowing ceilings
to improve and precip to transition to a more intermittent and
showery character late in the day. VFR ceilings in the warm sector
Thursday evening, with just VCSH to handle the precip and SSE winds
kicking up just over 10 kt.
&&
.Hydrology...
A series of winter storms are forecast to move across the Ohio
Valley starting early Thursday morning. The first wave is expected
to deliver up to an inch of rainfall. However, soils are not frozen
and still fairly dry, especially in western Kentucky, so little
runoff is expected.
The more important storm system is expected this weekend when a
series of waves along with copious amounts of moisture will make for
a couple of wet days. Over the entire 3 days, areas should average
between 2 and 3 inches of rain with the heavier amounts over
southern Kentucky. This rain will cause streams to rise and some
near bankfull crests could occur. However, since the rain will be
spread out over several days and current streamflows are not
elevated, any flooding that may occur should be minor. The best
chance for flooding will be in the western portion of the Green
River Basin.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...DENSE FOG ADVISORY UNTIL 8 AM EST THIS MORNING FOR KYZ049-
055>057-066-067.
$$
Update...........13
Short Term.......AMS
Long Term........MJP
Aviation.........RAS
Hydrology........CMC
AREA FORECAST DISCUSSION...corr to initials
NWS LOUISVILLE KY
1105 PM EST WED JAN 09 2013
.Forecast Update...
Issued 1105 PM EST Wed Jan 9 2013
After consulting with JKL, have gone ahead and upgraded to a Dense
Fog Advisory for our eastern edge for the rest of the night.
Issued 1019 PM EST Wed Jan 9 2013
Social media communications and surface obs show that the fog in the
Blue Grass has become thicker and more dense in spots, so have
introduced patchy dense fog (in addition to the patchy fog already
in the forecast) to our eastern counties. Also went ahead and put
out a SPS for patchy dense fog primarily from Carlisle to Liberty.
Issued at 842 PM EST Wed Jan 9 2013
A few ASOS locations as well as a couple of public reports have
shown that patchy fog has developed across southern and eastern
portions of the CWA. The HRRR actually shows this as well, at least
along the eastern edge of the CWA. Surface analysis shows a
corridor of lower dew point depressions reaching northeastward from
middle Tennessee into eastern Kentucky. Of course we`ve been
concerned with the incoming rain maker, but first, surface high
pressure is still sprawled across the region from the
mid-Mississippi Valley to the Carolinas, keeping winds light. So,
have added patchy fog to the forecast roughly along and southeast of
a Bowling Green-Lexington line. Will let the fog dissipate as rain
moves in and northeast breezes begin to pick up a little later
tonight.
Have also decided to throw in some patchy fog from northern Dubois
County to northern Washington County IN. Dew point depressions are
tightening there and those areas have the added factor of melting
snowcover. A few locations in the Wabash Valley have already
reported some light fog.
In addition, have adjusted the temperatures a bit, especially in the
usual cool spots.
A dense cirrus shield has overspread the region so we have increased
cloud cover to overcast for the rest of the night.
&&
.Short Term (Tonight through Thursday Night)...
Issued at 320 PM EST Wed Jan 9 2013
The weak tail end of a cold front passing mostly over southern
Indiana, northern KY, and locations northeast was located just south
of the Ohio River as of 1945Z. To the southeast of the front, a
thick deck of mid level clouds exists. However, this deck is making
steady progress eastward. Expect skies to go only partly cloudy for
a good portion of this evening before thick, low clouds start to
creep back in from the south after midnight.
After midnight a warm front will approach from the south as part of
a strengthening low pressure system over the OK/TX region. As this
weather system moves northeast to the western Great Lakes by Friday
morning, it will bring us 2 notable rounds of showers/isld storms
late tonight through Friday morning. The first round of elevated
showers/isld storms will come just after midnight tonight and
through tomorrow afternoon as the warm front lifts north through the
area. 6Z/12Z models have been slower with the arrival of these
rains so trended POPs back in time accordingly. We should see a
broad area of light rains slowly move north through the area for
much of Thurs. Any t-storms would likely be elevated north of the
warm front. However, some of the higher res model data suggests a
few scattered cellular structures during the late afternoon/evening
hours Thurs. Still these cells should be of little to no
consequence as morning clouds/rains will rob most areas of heating/
instability. The best chance for any scattered t-storms redeveloping
late Thurs afternoon/evening in the warm sector would be over south
central KY. Total QPF from this first wave of rainfall would be
under a half inch over most locations with areas along and west of
I-65 receiving the most rainfall.
The second wave of rains/isld t-storms will be late Thurs night into
Friday morning with the passage of a cold front. Before then, we
may continue to see scattered rains across the area Thurs evening.
The cold front looks to bring a solid line of rains with embedded
thunder through the area as it will be accompanied by a strong LLJ
(60-70 kts @ h85) and upper level jet support as the potent upper
trough passes just to our northwest. Friday morning would be our
best chance to see some strong to possibly marginally severe storms
due to such a strong LLJ passing through the area. A decent low
level inversion should keep most of the strongest winds aloft.
Still would not be surprise to see 35-50 mph winds mixing down
inside and outside of convection Friday morning. Small hail may
also be possible, but gusty winds and brief heavy rainfall would be
the main threats if any from storms Friday morning.
As far as temps go, they will be tricky over the next 36 hrs as
multiple frontal boundaries push through the area. Lows tonight
will range from the lower 30s over southern Indiana to mid and upper
40s over south central KY as a left over boundary stalls over the
region. Tomorrow expect highs ranging from the upper 40s north to
mid 60s south as we get a warm surge during the afternoon hours.
Thurs night, we`ll likely see a decrease in temps during the evening
hours with lows being reached just after midnight. A warm surge
will occur just ahead of cold front passage Friday morning allowing
temps to warm near dawn. Lows Thurs night should be in the upper
40s to around 60.
.Long Term (Friday through Wednesday)...
Issued at 305 PM EST Wed Jan 9 2013
...Wet and Unsettled Pattern Will Continue...
A building ridge off the Atlantic Coast and a digging western trough
will put the lower half of the Mississippi River Valley and the
entire Ohio River Valley under strong southwest flow aloft. This
will pump in plenty of moisture via an atmospheric river from the
Gulf, and set the stage for a very wet and active long term period.
The cold front associated with our first low pressure system
Thursday night will be entering our western forecast area around
daybreak Friday. Guidance continues to indicate instability will
decrease Thursday night into Friday morning, with some elevated
instability remaining. With the frontal passage at a diurnally
unfavorable time of day, the scenario projected by guidance is
reasonable. So, surfaced-based severe weather is looking less
likely. Surface-based instability will increase a bit through the
day Friday, as high temperatures warm well above normal into the low
and mid 60s. However, shear and large-scale forcing will decrease.
So, will continue with small hail and isolated strong wind gusts
being the main threats.
As this system departs Friday, it will leave behind a stalled
frontal boundary to our northwest that will not move much through
the weekend. Multiple shortwaves will ride over this boundary in
southwest flow aloft, with the first wave of rainfall expected
Saturday afternoon into Sunday. This band of rain should set up
across our northwestern forecast area for the overnight hours. The
rain will diminish a bit Sunday. However, another wave is expected
Sunday afternoon and evening, with yet another wave Sunday night
into Monday. With each wave, the southwest-northeast oriented
rainfall band will slowly track southeast.
Very warm temperatures and near record PWAT for this time
of year will be ushered in from the Gulf, with very high sub-cloud
layer relative humidity and warm cloud depth values in the 10-12Kft
range expected. This sets the stage for high precipitation
efficiency. Area average accumulations of 2-3 inches will be common
from Friday night through the day Monday, with locally higher
amounts possible. With this rain falling on wet ground provided by
the Wednesday and Thursday night/Friday systems, there could be some
areal flooding and rising rivers. Please see the hydrology section
below for more details on river impacts.
The surface front will sag southeast Sunday night, with some cooler
air filtering into our northern forecast area. Probabilistic and
plume data depict a small chance of some mixed precip on the back
side of the system. So, could see some mixed precip late Sunday
night through Monday morning before the system/deep moisture
departs. At this time, do not believe this will cause much of an
impact given the warm ground of late. Will monitor the thermal
profile and deep moisture over the next few model cycles.
As for temperatures, highs Saturday will reach the mid and upper
60s, with a cooling trend expected into Monday as the front slowly
pushes southeast. Highs Monday will range from the mid 30s in the
northwest to around 50 in the southeast. Low temperatures will show
a similar trend, with 40s and 50s Saturday night giving way to 20s
and 30s Monday night.
Guidance differs on the arrival of the next system, but ensemble
data suggests another round of precip Tuesday through Tuesday night.
With the surface boundary projected to be southeast of the forecast
area, cooler air in place across the forecast area, and steady
northeast surface winds, we could see another mixed precip event.
Confidence is not high on the overall thermal profile and placement
of precip, given the differences in model solutions, but ensemble
probabilities suggest a chance of mixed precip. Will continue to
monitor run-to-run model solutions for this system as well. It does
appear the system will exit the area Wednesday, with dry conditions
to follow. High temperatures Tuesday appear to range from mid 30s to
mid 40s, with highs a couple degrees cooler Wednesday. Overnight
lows will trend cooler as well, with generally mid 20s to low 30s
possible by Wednesday night.
&&
.Aviation (00Z TAF Issuance)...
Issued at 630 PM EST Wed Jan 9 2013
Flying conditions will deteriorate significantly during this TAF
period. A weakening upper level disturbance moving from Texas to
Missouri will pull a large area of rain northeastward along with
it. Rain will move into the BWG area after midnight tonight and
make it to the northern TAF sites by morning. The rain will then
continue through midday with low ceilings and MVFR visibilities
(possibly IFR at BWG).
During the afternoon hours a warm front will pass from south to
north across Kentucky, which will allow the rain to become more
scattered and will allow ceilings to rise a bit, though probably
stay MVFR.
Winds will gradually shift from northeast tonight to the east
tomorrow morning and to the southeast tomorrow afternoon as the warm
front approaches and passes on through.
&&
.Hydrology...
A series of winter storms are forecast to move across the Ohio
Valley starting early Thursday morning. The first wave is expected
to deliver up to an inch of rainfall. However, soils are not frozen
and still fairly dry, especially in western Kentucky, so little
runoff is expected.
The more important storm system is expected this weekend when a
series of waves along with copious amounts of moisture will make for
a couple of wet days. Over the entire 3 days, areas should average
between 2 and 3 inches of rain with the heavier amounts over
southern Kentucky. This rain will cause streams to rise and some
near bankfull crests could occur. However, since the rain will be
spread out over several days and current streamflows are not
elevated, any flooding that may occur should be minor. The best
chance for flooding will be in the western portion of the Green
River Basin.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
KY...DENSE FOG ADVISORY UNTIL 8 AM EST THURSDAY FOR KYZ049-055>057-
066-067.
$$
Update...........13
Short Term.......AMS
Long Term........MJP
Aviation.........13
Hydrology........CMC
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
834 PM CST Fri Jan 11 2013
.UPDATE...
/834 PM CST Fri Jan 11 2013/
Looking at the latest model runs for tomorrow`s potential
snowfall...some of the higher resolution models are hinting at a
potential band of snow that could develop further west of the main
area of precipitation, from east central KS into north central MO,
possibly including parts of the KC metro. Earlier SREF members,
specifically the ARW members, were the first to pick up on this
possibility and now the 00Z NAM and even RAP are picking up on this
as well. Frontogenesis progs and cross section analysis do indicate
the potential for locally banded snowfall developing somewhere over
eastern KS and western MO in the vicinity of a stalled 700-hPa
boundary. This would be highly sensitive to small-scale fluctuations
in the height field so it is not necessarily going to come to
fruition. However, a small potential is there for a narrow band of
1"-3" across this corridor, possibly as high as 4" in a few spots
given the banded nature.
With the very high uncertainty, will not make any changes to the
ongoing forecast and will let the overnight shift analyze the full suite
of 00Z models before making the final call on this potential snow
band. But for now, wanted to raise awareness that *if* the trend of
the NAM, RAP and SREF were to continue, then our current snowfall
forecast for the KC area could be too low.
Hawblitzel
&&
.DISCUSSION...
The main focus for the next three days centers on the potential for
accumulating snowfall Saturday night:
Tonight - Saturday:
The strong cold front that will be tracking through the forecast
area tonight through Saturday was situated from northeastern
Nebraska through northwestern Kansas. This front is expected to
start entering northwestern Missouri around midnight tonight and
then be through the forecast area by mid morning. The night will
start rather mild with decent mixing ahead of the front keeping
temperatures ahead of the front in the upper 40s and 50s.
Temperatures will fall into the 20s and 30s behind the front with
temperatures nearly steady during the day Saturday. In fact, we will
likely see our highs early in the day before the cold advection
overwhelms things. Highs on Saturday should range from the upper 20s
in far northwestern Missouri to the lower 40s in parts of central
Missouri.
Saturday night:
As the strong cold advection is occurring, a weak system will move
northwest out of the Southern Plains and track across Arkansas and
southern Missouri. This system will interact with a strong jet
stream moving across the region and for part of the night much of
the forecast area will be the right rear quadrant of the upper jet.
This will enable broad frontogenetic forcing leading to a brief
period of strong upward lift. This will lead to several hours of
snowfall across areas mainly east of Interstate 35. The heaviest
accumulations of snow should be over portions of central Missouri
where as much as 2 inches looks possible given the available
moisture, the intensity of the system and the short duration of the
event itself. Further west, across east central Kansas, west central
Missouri and northwestern Missouri accumulations will be less than
an inch with little or no accumulation expected across far
northwestern Missouri and extreme northeastern Kansas.
Sunday:
This system will be quick-hitting and is expected to be out of the
region by late Sunday morning. As the system exits, skies should
clear out but temperatures will continue to be cold with highs in
the 20s and 30s.
CDB
Medium Range (Monday through Friday)...
Through the medium range, the pattern will gradually transition from
deep troughing over the Plains and eastern Rockies to warmer, more
zonal flow throughout the CONUS. Temperatures on Monday and Tuesday
continue to look colder than average with chilly Canadian air
continuing to flow into the region, then will gradually rise to near
or just above normal for Wednesday through at least Thursday. There
is some degree of disagreement among the longer-range models on the
extent and progression of arctic air into the CONUS by the end of
the work week as a broad, deep trough edges across the Canadian
border, which could strongly impact the temperature forecast. If the
12z ECMWF verifies going into the weekend, very cold temperatures
could slide into the CWA, despite a current consensus of slightly
above normal temperatures for that period. Thus, this will be
something to monitor for significant changes as this time period
draws closer.
No precipitation is expected through this period, as surface high
pressure becomes semi-permanent across the central and southern
Plains and the split jet structure keeps systems confined to far
northern and southeastern portions of the country.
Laflin
&&
.AVIATION...
For the 00Z TAFs...pressure gradient remains tight ahead of a cold
front that currently stretches from just north of OMA into central
KS. Expect southerly winds to continue gusting in the 20-25 kt range
ahead of the front, which will move into western MO around 05Z-06Z.
An area of MVFR cigs behind this front may make it as far east as
western MO, so introduced MVFR cig restrictions for a few hours
following frontal passage. There could also be a period of gusts
during this time as well as winds quickly shift to the west and then
northwest, where they will stay for the remainder of the TAF period.
Hawblitzel
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION...UPDATED
NWS BILLINGS MT
927 PM MST WED JAN 9 2013
.SHORT TERM...VALID FOR THU AND FRI...
WINDS AT THE LIVINGSTON WIND DOT SITE WERE MEETING ADVISORY
CRITERIA SINCE JUST AFTER 02Z. MSAS SHOWED A SURFACE LOW NW OF
HARLOWTON WHICH WAS ENHANCING THE PRESSURE GRADIENT LOCALLY OVER
THE KLVM AREA. THE RAP PICKED UP ON THE SURFACE LOW AND MOVED IT
SE OVER THE NEXT FEW HOURS...SO WOULD EXPECT THE WINDS TO DECREASE
IN THE KLVM AREA.
GIVEN 03Z TEMPERATURES IN THE 40S OVER MOST OF THE AREA AND
EXTENSIVE CLOUD COVER STREAMING OVER THE AREA ON IR IMAGERY...HAVE
RAISED OVERNIGHT LOWS.
NEW WRF CAME IN WITH SOME CHANGES FROM IT/S PREVIOUS RUN...WHILE
NEW GFS WAS LOOKING SIMILAR TO IT/S PREVIOUS RUN. NEW WRF WAS SLOWER
WITH EASTWARD MOVEMENT OF UPPER LOW THU NIGHT AND STILL BROUGHT COLD
FRONT THROUGH THE AREA LATE THU AFTERNOON THROUGH THU EVENING. NEW
RUN WAS SLOWER WITH COLDER AIR ASSOCIATED WITH THE LOW AS WELL.
PRECIPITATION WAS SLOW TO MOVE INTO THE AREA ON BOTH MODELS...AND
THE POPS OVER THE WESTERN ZONES MAY BE A BIT OVERDONE THU MORNING.
WILL LET NEXT SHIFT EVALUATE THIS MORE CLOSELY. ALSO NEW WRF KEPT
THE PRECIPITATION BULLSEYE...THAT WAS OVER THE SE ZONES...SE OF
THE AREA FRI AFTERNOON. OTHERWISE WRF QPF AMOUNTS OVER THE
FORECAST AREA WERE SIMILAR TO THE PREVIOUS RUN. NOTED NEW MET
GUIDANCE LOWERED SNOW AMOUNTS THU NIGHT AND RAISED THEM FOR
FRI/FRI NIGHT...LIKELY DUE TO SLOWER SYSTEM MOVEMENT. WRF
CONTINUED TO SHOW HIGHER QPF AMOUNTS THAN GFS. GFS STILL SHOWED
LATE THU NIGHT THROUGH FRI AS BEST TIME FOR ACCUMULATING SNOW FROM
KBIL W. SO...SOME CHANGES MAY BE NEEDED TO SLOW PRECIPITATION
TIMING FOR THU. NO STRONG REASONS SEEN TO CHANGE ANY SNOW
AMOUNTS.
GIVEN THE HIGHER TEMPERATURES EXPECTED TONIGHT AND THE SLOWER
ADVANCEMENT OF THE PRECIPITATION...HAVE RAISED HIGHS ON THU.
ARTHUR
.LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED...
THE EXTENDED FORECAST PERIOD BEGINS SATURDAY NIGHT...AS THE LAST
REMNANTS OF THE APPROACHING WINTER STORM SYSTEM IS EXITING THE
REGION TO THE EAST. LITTLE ADDITIONAL ACCUMULATIONS ARE
ANTICIPATED AT THIS TIME. FOLLOWING THIS SYSTEM IT APPEARS
NORTHWEST FLOW ALOFT WILL REMAIN IN CONTROL ACROSS THE
REGION...AND COMBINED WITH EXTENSIVE SNOW COVER...EXPECT
TEMPERATURES TO REMAIN ON THE COOL SIDE. HIGHS WILL ONLY CLIMB TO
TEENS AND LOW 20S BY MONDAY...AND BACK ABOVE FREEZING IN SOME
AREAS WEDNESDAY. THIS IS WELL BELOW CURRENT GUIDANCE...BUT CANNOT
SEE MUCH WARMER TEMPERATURE BECOMING REALITY WITH THE SNOW COVER
EXPECTED...AND POTENTIAL FOR SEVERAL REINFORCING WAVES OF COLD AIR
AND PRECIP ACROSS THE REGION THROUGH THE BEGINNING OF THE WORK
WEEK.
AS MENTIONED...TIMING REMAINS UNCERTAIN WITH REGARD TO REINFORCING
WAVES INTO THE REGION...SO HAVE CONTINUED WITH INHERITED SLIGHT
CHANCE TO CHANCE POPS THROUGH THE REMAINDER OF THE PERIOD.
INDICATIONS AT THIS TIME ARE FOR WAVES THROUGH THE REGION LATE
MONDAY AND LATE TUESDAY AT THIS TIME.
ALSO OF INTEREST IS A RETURN OF INCREASED WIND ACROSS THE WESTERN
AREAS...MAINLY WEST OF KBIL...INCLUDING KLVM BY SUNDAY NIGHT. ALTHOUGH
WINDS ARE NOT EXPECTED TO APPROACH SEVERE CRITERIA...BLOWING SNOW
WILL BE POSSIBLE. HAVE INCLUDED BLOWING SNOW ACROSS THOSE WESTERN
AREAS SUNDAY NIGHT THROUGH MONDAY NIGHT. WINDS WILL REMAIN BREEZY
THROUGH THE REMAINDER EXPECT WINDS TO TAPER OFF TUESDAY
NIGHT...AND SNOW TO BE CRUSTING OVER BY TUESDAY. AAG
&&
.AVIATION...
STRONG SOUTHWEST WINDS WILL BE LIKELY IN THE KLVM AREA AND ALONG
FAVORED LOCATIONS OVER THE FOOTHILLS UNTIL 0900UTC. OTHERWISE
EXPECT INCREASING CLOUDS AND LOWERING CEILINGS DURING THE DAY ON
THURSDAY OVER WESTERN AREAS IN THE MORNING SHIFTING EAST BY
AFTERNOON. SNOWFALL WILL BECOME WIDESPREAD FROM WEST TO EAST FROM
THURSDAY AFTERNOON INTO FRIDAY EVENING. BORSUM
&&
.PRELIMINARY POINT TEMP/POPS...
THU FRI SAT SUN MON TUE WED
-----------------------------------------------------------
BIL 034/038 007/008 903/013 002/018 001/020 013/027 020/034
07/O ++/S 61/B 11/B 11/N 32/S 22/J
LVM 032/034 002/010 906/012 901/016 000/016 008/025 013/028
2+/O +9/S 51/B 11/B 22/J 32/S 22/J
HDN 030/037 008/009 904/013 903/017 003/019 011/026 018/032
06/S ++/S 62/S 11/B 11/B 33/S 22/J
MLS 025/035 005/007 908/008 906/013 902/016 007/022 015/029
04/S ++/S 83/S 11/B 11/E 23/S 22/J
4BQ 026/038 008/009 905/010 904/016 902/017 007/022 015/030
03/S ++/S 93/S 11/B 11/E 23/S 22/J
BHK 021/036 003/005 908/004 905/012 903/013 002/018 011/027
03/S ++/S 93/S 11/B 11/E 23/S 22/J
SHR 029/039 006/009 903/011 904/018 901/018 009/025 017/033
03/O ++/S 72/S 11/B 11/B 23/S 32/J
&&
.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING IN EFFECT FROM NOON THURSDAY TO 6 AM MST
SATURDAY FOR ZONES 28-29-34-35-38>42-56-57-63>68.
WINTER STORM WATCH IN EFFECT FROM THURSDAY EVENING THROUGH
SATURDAY AFTERNOON FOR ZONES 30>33-36-37-58.
WY...WINTER STORM WATCH IN EFFECT FROM THURSDAY EVENING THROUGH
SATURDAY AFTERNOON FOR ZONES 98-99.
&&
$$
WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
843 PM CST FRI JAN 11 2013
.UPDATE...FOG AND LIGHT FREEZING RAIN WHICH WERE OBSERVED AT
VARIOUS POINTS ACROSS THE CWA EARLIER THIS EVENING HAVE SINCE
DISSIPATED. WENT AHEAD AND REMOVED ANY SUCH WORDING FROM THE GRIDS
AND HWO. ANY REPORTS OF BLOWING DUST FROM ACROSS OUR KANSAS
COUNTIES HAVE ALSO CEASED SO WENT AHEAD AND REMOVED SUCH WORDING
FROM THE FORECAST. AS OF 02Z THE LOW LEVEL BAROCLINIC ZONE WAS
LOCATED FROM NEAR KLNK...TO NEAR KHJH...TO NEAR KK61. THE SURFACE
WIND HAS TRANSITIONED TO THE NORTHWEST FOR MOST LOCATIONS ACROSS
OUR CWA AS A RESULT. LOW LEVEL PRESSURE RISES POST-FROPA ARE
INDUCING AN INCREASING LOW LEVEL PRESSURE GRADIENT ACROSS MUCH OF
THE CWA AT THIS HOUR...WITH THE STRONGEST PRESSURE RISES BEING
OBSERVED THROUGH THE TRI-CITIES AREA. A THIN CORRIDOR OF SUSTAINED
WIND NEAR 25KTS IS BEING OBSERVED FROM KAUH...TO KHSI...TO
KGRI...AND SOUTH TO KK82...WITH A SUSTAINED WIND CLOSER TO THE
15-20KT RANGE AT LOCATIONS FARTHER EAST AND WEST. SHORT TERM
GUIDANCE FROM THE RAP SUGGESTS THE LOW LEVEL PRESSURE RISES SHOULD
DIMINISH ACROSS MUCH OF OUR AREA HEADING INTO THE OVERNIGHT HOURS
AND WITH A RESULTANT DECREASE IN THE LOW LEVEL PRESSURE
GRADIENT...THE LOW LEVEL WIND FIELD SHOULD ALSO DIMINISH IN
INTENSITY. THIS IS A SOLUTION ALSO SUPPORTED BY THE NAM AND
OPERATIONAL GFS. THE ONLY EXCEPTION MAY BE ACROSS OUR FAR
NORTH/NORTHEASTERN CWA WHERE THE INCREASED LOW LEVEL PRESSURE
GRADIENT MAY REMAIN INTACT FOR A FEW HOURS LONGER...THUS ALLOWING
FOR A SOMEWHAT STRONGER WIND HEADING INTO THE EARLY MORNING HOURS
SATURDAY. GIVEN ALL THIS...WENT AHEAD AND CANCELLED THE WIND
ADVISORY WHICH WAS IN EFFECT FOR SOME OF OUR KANSAS COUNTIES. ALSO
WENT AHEAD AND PUSHED THE WIND ADVISORY...IN EFFECT FOR OUR
NEBRASKA COUNTIES...NORTH OF I-80 WHERE THE STRONGER LOW LEVEL
PRESSURE GRADIENT IS EXPECTED TO LINGER LONGER. THIS IS A DECISION
WHICH SEEMS A BIT SHAKY RIGHT NOW GIVEN THAT THE TRI-CITIES HAVE
SEEN A DRASTIC INCREASE IN WIND SPEED IN THE LAST HOUR BUT
AGAIN...THE CURRENT BELIEF IS THAT THE WIND WILL DIMINISH WITHIN
ANOTHER HOUR ACROSS THE TRI-CITIES..LEAVING ONLY OUR FAR
NORTH/NORTHEAST AT AN INCREASED RISK OF OBSERVING A WIND WHICH
MEETS WIND ADVISORY CRITERIA. ALSO WENT AHEAD AND TWEAKED HOURLY
TEMPERATURE...DEWPOINT AND SKY GRIDS TO BETTER REFLECT CURRENT
TRENDS.
&&
.PREV DISCUSSION... /ISSUED 621 PM CST FRI JAN 11 2013/
UPDATE...EVENING UPPER AIR ANALYSIS PER RAP ANALYSIS DATA
INDICATES LONGWAVE TROUGHING OVER THE WESTERN HALF OF THE
CONUS...WITH RIDGING OVER THE EAST. MID AND UPPER LEVEL JET ENERGY
EXTENDS FROM THE FOUR CORNERS REGION...NORTHEAST ACROSS THE
CENTRAL PLAINS...AND THEN FARTHER NORTHEAST INTO SOUTHERN AND
SOUTHEASTERN CANADA. MID AND UPPER TROPOSPHERIC FLOW IS QUITE
STRONG OVER OUR AREA AS A RESULT...MAXING OUT AT AROUND 150KTS PER
23Z RAP ANALYSIS SOUNDING DATA FROM KGRI. ITS WORTH NOTING THAT
THE LOWER TROPOSPHERE IS ALSO EXHIBITING VERY STRONG
FLOW...50-55KTS ALL THE WAY TO THE TOP OF THE LOW LEVEL INVERSION
NEAR 800MB. WATER VAPOR IMAGERY INDICATES A CLOSED MID LEVEL LOW
OVER WESTERN WYOMING. A MID LEVEL SHORT WAVE IS ALSO NOTED OVER
THE CENTRAL HIGH PLAINS...ADVANCING NORTHEAST ACROSS THE REGION
ALONG THE EASTERN PERIPHERY OF THE CLOSED MID LEVEL LOW. WATER
VAPOR IMAGERY ALSO INDICATES INCREASED VALUES OF MID LEVEL
MOISTURE EXTENDING FROM WEST-TEXAS...NORTHEAST INTO THE CENTRAL
PLAINS AND MID TO UPPER MISSISSIPPI VALLEY. A MID LEVEL DRY
INTRUSION IS ALSO NOTED EXTENDING FROM THE FOUR CORNERS REGION
NORTHEAST INTO THE CENTRAL HIGH PLAINS. AT THE SURFACE A ~992MB
LOW IS NOTED BETWEEN KMCK AND KHLC...WITH AN ASSOCIATED FRONTAL
BOUNDARY EXTENDING EAST/NORTHEAST FROM THE LOW ACROSS CENTRAL AND
NORTHEASTERN NEBRASKA...AND A COLD FRONT EXTENDING WEST/SOUTHWEST
FROM THE LOW INTO NORTHWESTERN KANSAS AND SOUTHEASTERN COLORADO. A
DRY LINE IS ALSO NOTED EXTENDING SOUTH FROM THE LOW ACROSS WESTERN
KANSAS.
BLOWING DUST REMAINED EVIDENT ON VISIBLE SATELLITE IMAGERY UNTIL
SUNSET THIS EVENING BUT AT THIS TIME HAVE NO REASON TO BELIEVE IT
HAS SUBSIDED AS GUSTY WINDS AND MINOR VISIBILITY RESTRICTIONS ARE
STILL BEING REPORTED FROM KPHG TO KHLC. THAT BEING SAID...GIVEN
THE LINGERING SNOWPACK AND WET GROUNDS ACROSS OUR AREA IT APPEARS
UNLIKELY VISIBILITY RESTRICTIONS WILL WORSEN THROUGH THE NEXT
COUPLE OF HOURS...AND WITH VISIBILITY GREATER THAN 1 1/2SM AT
KPHG...AM COMFORTABLE WITH THE BLOWING DUST MENTION IN THE CURRENT
WIND ADVISORY AND HWO. NO PLANS FOR A FORMAL BLOWING DUST ADVISORY
AT THIS TIME.
A THIN CORRIDOR OF DENSE FOG HAS DEVELOPED ALONG THE LOW LEVEL
BAROCLINIC ZONE CURRENTLY PUSHING ACROSS THE CWA. KHSI DROPPED TO
1/4SM FOR A BRIEF TIME THIS AFTERNOON...WITH LOCATIONS FROM KAUH
TO OSCEOLA AND KJYR ALSO REPORTING SIGNIFICANT VISIBILITY
RESTRICTIONS IN FOG THROUGH THE PAST COUPLE OF HOURS. WHAT FOG IS
REALIZED DOES NOT LAST LONG AS IT CONTINUES TO MOVE EAST...BUT
WENT AHEAD AND INSERTED PATCHY DENSE FOG IN THE GRIDS THROUGH 01Z
TO ACCOUNT FOR ONGOING ACTIVITY.
MID LEVEL THERMAL ADVECTION AND MODEST DPVA AHEAD OF THE MID LEVEL
SHORT WAVE OVER THE CENTRAL HIGH PLAINS IS PROMOTING WIDESPREAD
PRECIPITATION OVER WESTERN NEBRASKA...WITH SOME OF THIS
PRECIPITATION MANAGING TO CLIP FAR WEST/NORTHWESTERN PORTIONS OF
OUR CWA IN THE LAST HOUR. PROXIMITY SOUNDINGS FROM OUR
WEST/NORTHWEST CWA PER RAP ANALYSIS DATA SUGGESTS AN ELEVATED WARM
LAYER EXISTS BETWEEN 850 AND 800MB...AND PERIODIC LIGHT FREEZING
RAIN WAS REPORTED IN DAWSON COUNTY IN THE LAST HOUR. GIVEN THE
CURRENT RETURNS FROM KUEX...ANY FREEZING RAIN THAT IS REALIZED
SHOULD REMAIN VERY LIGHT AND SHOULD NOT PRODUCE MUCH IN THE WAY OF
ICE ACCUMULATION. THAT BEING SAID...FELT MORE COMFORTABLE
INTRODUCING LIGHT FREEZING RAIN WORDING TO THE GRIDS AND
HWO...THROUGH 01Z...FOR OUR FAR WEST/NORTHWEST CWA.
WIND ADVISORIES ACROSS OUR AREA REMAIN INTACT WITH NO CHANGES MADE
AT THIS TIME. THOSE HEADLINES WILL BE EVALUATED AND POTENTIALLY
ADJUSTED LATER THIS EVENING. REMAINDER OF THE FORECAST REMAINS IN
GOOD SHAPE...WITH ONLY MINOR TWEAKS MADE TO HOURLY
TEMPERATURE...WIND...AND DEWPOINT GRIDS TO BETTER REFLECT REALITY.
PREV DISCUSSION... /ISSUED 523 PM CST FRI JAN 11 2013/
AVIATION...00Z KGRI TAF. MVFR CONDITIONS TO CONTINUE THROUGH
07Z...WITH VFR CONDITIONS EXPECTED 07Z-21Z...AND ANOTHER ROUND OF
MVFR CONDITIONS POSSIBLE AFTER 21Z. RESTRICTED VISIBILITY TO
AROUND 3SM WILL ALSO BE POSSIBLE IN FOG 02-07Z. THE SURFACE WIND
WILL INTENSIFY FROM THE NORTHWEST TONIGHT...SUSTAINED NEAR 26KTS
AND GUSTING TO NEAR 34KTS 02-07Z. A DIMINISHING SURFACE WIND IS
THEN EXPECTED AT THE TERMINAL THROUGH THE REMAINDER OF THE TAF
PERIOD.
PREV DISCUSSION... /ISSUED 405 PM CST FRI JAN 11 2013/
SHORT TERM...NOW THROUGH SATURDAY
WINTERS COLD RETURNS TO THE CNTRL PLAINS TONIGHT WITH A PERIOD OF
STRONG WIND GUSTS IN THE TRANSITION...
AN SPS WAS ISSUED AT 2032Z FOR THE BLOWING DUST AND WILL PROBABLY
BE UPDATED BY THE BOTTOM OF THE HOUR.
WIND ADVISORIES CONTINUE AS POSTED. NPW WAS UPDATED/SENT AT 324 PM
TO RAISE ADDITIONAL AWARENESS OF BLOWING DUST OVER KS.
NOW: STRONG COLD FRONT IS SAGGING SE THRU CNTRL NEB. IT WAS LAST
SEEN ON THE LNX 88D AT 1825Z JUST NW OF BBW. THE TIMING TOOL BRINGS
IT INTO GRI BY 2230Z. 992 MB LOW WAS TRACKING ALONG THE KS-NEB
BORDER...S OF WHERE IT WAS FCST 24 HRS AGO.
THE FRONT IS AHEAD OF SCHEDULE SO USED THE RAP FOR SHORT-TERM WINDS.
THE 18Z RAP SUGGESTS IT FINALLY CUTS NE THIS EVNG ACROSS ERN NEB.
BLOWING DUST: A BURST OF 33-41 KT WINDS HAS RESULTED IN A LARGE AREA
OF BLOWING DUST THAT ORIGINATED OVER ERN CO. TIMING TOOL WILL BRING
THIS INTO OUR KS COUNTIES AROUND 445 PM AND IT WILL CONTINUE UNTIL
WIND SHIFT ASSOCIATED WITH COLD FRONTAL PASSAGE.
CONTEMPLATED CANCELLING THE WIND ADVISORY FOR N-CNTRL KS SINCE WINDS
HAVE BEEN WELL BELOW ADVISORY SUSTAINED OR GUSTS. BUT GIVEN MULTIPLE
G40 KTS WITH THAT DUST...HAVE CONTINUED ADVISORY.
A LARGE AREA OF STRATUS IS EXPECTED TO SINK S BEHIND THE FRONT TNGT
IN THE WAKE OF THE DEPARTING LOW. HOW FAR S OVC EXTENDS REMAINS
UNCERTAIN GIVEN DOWNSLOPING WINDS WILL TEND TO BREAK IT UP.
WIND: 3 HR PRES RISES ARE ONLY 3 MB OVER THE NEB PANHANDLE AT 21Z.
THE NAM IS OVER ESTIMATING THIS BY 5 MB AND THE RAP BY 3 MB. THINK
THE TREND IS RIGHT WITH EXPANDING/INCREASING PRES RISES AS THE LOW
ACCELERATES NEWD THIS EVE...BUT THE MAGNITUDE MAY BE OVERDONE.
CONFIDENCE IS ABOVE AVERAGE FOR VERIFYING THE ADVISORY OVER N-CNTRL
KS AHEAD OF THE FRONT. IT/S TAKEN ALL DAY BUT IT WILL VERIFY
22Z-03Z. BEHIND THE FRONT HAVE YET TO SEE ADVISORY LEVEL WINDS
DEVELOP. LOW-LEVELS WILL BECOME UNSTABLE IN CAA THIS EVE AND BUT
THIS APPEARS A MARGINAL WIND EVENT SO VERIFYING NEB WIND ADVISORY IS
BELOW AVERAGE ALONG AND S OF I-80. BEST CHANCE FOR A ONE-TIME 45 MPH
GUST WILL BE N OF THE TRI-CITIES. THE BEST CHANCE FOR VERIFYING
ALONG AND S OF I-80 WILL PROBABLY BE A BRIEF PERIOD OF SUSTAINED
WINDS OF 30 MPH.
TNGT: M/CLOUDY WITH BLUSTERY NW WINDS. SOME FLURRIES OR BRIEF SHSN
WILL OCCUR 6PM-12AM IN PULSE OF CAA. TEMP GUIDANCE WAS IN GOOD
AGREEMENT AND USED THE CONSENSUS OF ALL GUIDANCE WHICH BASICALLY
PUTS TEMPS NEAR NORMAL.
SAT: A MIX OF CLOUDS/SUN. UNSURE HOW MUCH STRATOCU GETS TRAPPED
UNDER FRONTAL INVERSION. HAVE ALREADY INCREASED CLOUDS ABOVE
PREVIOUS GID FCST AND IF NAM BUFKIT IS RIGHT THAN WE WILL BE TOO
LOW ON CLOUD COVER. REGARDLESS...PATCHES JET STREAM CIRRUS WILL
KEEP THE SKY AT LEAST P/CLOUDY. STILL A BLUSTERY NW WIND WITH GUST
UP TO 30 MPH FORENOON. TEMPS ARE NAM 2M TEMPS WHICH IS CLOSE TO
THE PREVIOUS FCST...ABOUT 12F BELOW NORMAL.
LONG TERM...SATURDAY NIGHT THROUGH FRIDAY. THIS WILL LIKELY BE A
DRY PERIOD WITH TEMPERATURES GENERALLY WARMING THROUGH AT LEAST
WEDNESDAY. MORE UNCERTAINTY ENTERS THE PICTURE BY THURSDAY AND
FRIDAY.
SATURDAY NIGHT THROUGH MONDAY...A COLD AREA OF ARCTIC HIGH PRESSURE
WILL BEGIN TO SLIDE INTO THE PLAINS SATURDAY NIGHT INTO SUNDAY AND
REMAIN THROUGH AT LEAST MONDAY. THERE WILL BE A LARGE UPPER TROUGH
SITUATED OVER THE PLAINS BUT ALL OF THE MOISTURE WILL BE AT THE
LEADING EDGE OF THIS TROUGH AND WELL OFF TO OUR EAST. HIGH
TEMPERATURES WILL BE STUCK IN THE 20S ON SUNDAY AND POSSIBLY MONDAY
AS WELL. SOME AREAS THAT ARE COMPLETELY FREE OF SNOW COVER MAY REACH
THE LOWER 30S ON MONDAY.
TUESDAY AND WEDNESDAY...THE 12Z ECMWF PUSHES THE SFC HIGH OFF TO OUR
SOUTH ALLOWING FOR WEST SOUTHWEST DOWNSLOPE SFC WINDS. THE SHALLOW
COLD AIR WILL GRADUALLY MODERATE WITH HIGH TEMPERATURES BACK INTO
THE 30S ON TUESDAY AND PROBABLY 40S BY WEDNESDAY.
THURSDAY THROUGH FRIDAY...THERE IS A SUBSTANTIAL AMOUNT OF MODEL
UNCERTAINTY WITH REGARD TO TEMPERATURES. HOWEVER...THERE IS GOOD
MODEL AGREEMENT IN DRY CONDITIONS. THE ECMWF BRINGS A COLD FRONT
THROUGH WEDNESDAY NIGHT WITH STRONG COLD AIR ADVECTION ON THURSDAY.
THE 850 MB TEMPERATURES THURSDAY EVENING RANGE FROM -15C ON THE 12Z
ECMWF TO 5C ON THE 12Z GFS FOR A SIGNIFICANT 20C DEGREE SPREAD. THE
OFFICIAL FORECAST IS SOMEWHERE IN THE MIDDLE OF THESE TWO MODELS
CALLING FOR ABOVE FREEZING HIGHS IN THE UPPER 30S TO LOWER 40S.
HOWEVER...THESE HIGHS MAY VERY WELL BE TOO WARM. THE ONGOING
STRATOSPHERIC WARMING EVENT WILL LIKELY RESULT IN THE TRANSITION TO
A NEGATIVE ARCTIC OSCILLATION PATTERN...WHICH TENDS TO BRING THE
COLD AIR DOWN OUT OF CANADA INTO THE EASTERN TWO THIRDS OF THE
CONUS. THEREFORE...I WOULD LEAN MORE TOWARDS THE ECWMF AND THE
POSSIBILITY OF COLDER TEMPERATURES THAN WHAT WE ARE OFFICIALLY
CALLING FOR AS THIS BETTER FITS THE -AO PATTERN. IF THE 12Z ECMWF
COLDER TREND CONTINUES...WE WILL NEED TO BE LOWERING OUR THURSDAY
AND FRIDAY HIGH TEMPERATURES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY UNTIL 1 AM CST SATURDAY FOR NEZ039>041-046>049.
KS...NONE.
&&
$$
843 PM UPDATE/621 PM UPDATE/AVIATION...BRYANT
SHORT TERM...HALBLAUB
LONG TERM...WESELY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
621 PM CST FRI JAN 11 2013
.UPDATE...EVENING UPPER AIR ANALYSIS PER RAP ANALYSIS DATA
INDICATES LONGWAVE TROUGHING OVER THE WESTERN HALF OF THE
CONUS...WITH RIDGING OVER THE EAST. MID AND UPPER LEVEL JET ENERGY
EXTENDS FROM THE FOUR CORNERS REGION...NORTHEAST ACROSS THE
CENTRAL PLAINS...AND THEN FARTHER NORTHEAST INTO SOUTHERN AND
SOUTHEASTERN CANADA. MID AND UPPER TROPOSPHERIC FLOW IS QUITE
STRONG OVER OUR AREA AS A RESULT...MAXING OUT AT AROUND 150KTS PER
23Z RAP ANALYSIS SOUNDING DATA FROM KGRI. ITS WORTH NOTING THAT
THE LOWER TROPOSPHERE IS ALSO EXHIBITING VERY STRONG
FLOW...50-55KTS ALL THE WAY TO THE TOP OF THE LOW LEVEL INVERSION
NEAR 800MB. WATER VAPOR IMAGERY INDICATES A CLOSED MID LEVEL LOW
OVER WESTERN WYOMING. A MID LEVEL SHORT WAVE IS ALSO NOTED OVER
THE CENTRAL HIGH PLAINS...ADVANCING NORTHEAST ACROSS THE REGION
ALONG THE EASTERN PERIPHERY OF THE CLOSED MID LEVEL LOW. WATER
VAPOR IMAGERY ALSO INDICATES INCREASED VALUES OF MID LEVEL
MOISTURE EXTENDING FROM WEST-TEXAS...NORTHEAST INTO THE CENTRAL
PLAINS AND MID TO UPPER MISSISSIPPI VALLEY. A MID LEVEL DRY
INTRUSION IS ALSO NOTED EXTENDING FROM THE FOUR CORNERS REGION
NORTHEAST INTO THE CENTRAL HIGH PLAINS. AT THE SURFACE A ~992MB
LOW IS NOTED BETWEEN KMCK AND KHLC...WITH AN ASSOCIATED FRONTAL
BOUNDARY EXTENDING EAST/NORTHEAST FROM THE LOW ACROSS CENTRAL AND
NORTHEASTERN NEBRASKA...AND A COLD FRONT EXTENDING WEST/SOUTHWEST
FROM THE LOW INTO NORTHWESTERN KANSAS AND SOUTHEASTERN COLORADO. A
DRY LINE IS ALSO NOTED EXTENDING SOUTH FROM THE LOW ACROSS WESTERN
KANSAS.
BLOWING DUST REMAINED EVIDENT ON VISIBLE SATELLITE IMAGERY UNTIL
SUNSET THIS EVENING BUT AT THIS TIME HAVE NO REASON TO BELIEVE IT
HAS SUBSIDED AS GUSTY WINDS AND MINOR VISIBILITY RESTRICTIONS ARE
STILL BEING REPORTED FROM KPHG TO KHLC. THAT BEING SAID...GIVEN
THE LINGERING SNOWPACK AND WET GROUNDS ACROSS OUR AREA IT APPEARS
UNLIKELY VISIBILITY RESTRICTIONS WILL WORSEN THROUGH THE NEXT
COUPLE OF HOURS...AND WITH VISIBILITY GREATER THAN 1 1/2SM AT
KPHG...AM COMFORTABLE WITH THE BLOWING DUST MENTION IN THE CURRENT
WIND ADVISORY AND HWO. NO PLANS FOR A FORMAL BLOWING DUST ADVISORY
AT THIS TIME.
A THIN CORRIDOR OF DENSE FOG HAS DEVELOPED ALONG THE LOW LEVEL
BAROCLINIC ZONE CURRENTLY PUSHING ACROSS THE CWA. KHSI DROPPED TO
1/4SM FOR A BRIEF TIME THIS AFTERNOON...WITH LOCATIONS FROM KAUH
TO OSCEOLA AND KJYR ALSO REPORTING SIGNIFICANT VISIBILITY
RESTRICTIONS IN FOG THROUGH THE PAST COUPLE OF HOURS. WHAT FOG IS
REALIZED DOES NOT LAST LONG AS IT CONTINUES TO MOVE EAST...BUT
WENT AHEAD AND INSERTED PATCHY DENSE FOG IN THE GRIDS THROUGH 01Z
TO ACCOUNT FOR ONGOING ACTIVITY.
MID LEVEL THERMAL ADVECTION AND MODEST DPVA AHEAD OF THE MID LEVEL
SHORT WAVE OVER THE CENTRAL HIGH PLAINS IS PROMOTING WIDESPREAD
PRECIPITATION OVER WESTERN NEBRASKA...WITH SOME OF THIS
PRECIPITATION MANAGING TO CLIP FAR WEST/NORTHWESTERN PORTIONS OF
OUR CWA IN THE LAST HOUR. PROXIMITY SOUNDINGS FROM OUR
WEST/NORTHWEST CWA PER RAP ANALYSIS DATA SUGGESTS AN ELEVATED WARM
LAYER EXISTS BETWEEN 850 AND 800MB...AND PERIODIC LIGHT FREEZING
RAIN WAS REPORTED IN DAWSON COUNTY IN THE LAST HOUR. GIVEN THE
CURRENT RETURNS FROM KUEX...ANY FREEZING RAIN THAT IS REALIZED
SHOULD REMAIN VERY LIGHT AND SHOULD NOT PRODUCE MUCH IN THE WAY OF
ICE ACCUMULATION. THAT BEING SAID...FELT MORE COMFORTABLE
INTRODUCING LIGHT FREEZING RAIN WORDING TO THE GRIDS AND
HWO...THROUGH 01Z...FOR OUR FAR WEST/NORTHWEST CWA.
WIND ADVISORIES ACROSS OUR AREA REMAIN INTACT WITH NO CHANGES MADE
AT THIS TIME. THOSE HEADLINES WILL BE EVALUATED AND POTENTIALLY
ADJUSTED LATER THIS EVENING. REMAINDER OF THE FORECAST REMAINS IN
GOOD SHAPE...WITH ONLY MINOR TWEAKS MADE TO HOURLY
TEMPERATURE...WIND...AND DEWPOINT GRIDS TO BETTER REFLECT REALITY.
&&
.PREV DISCUSSION... /ISSUED 523 PM CST FRI JAN 11 2013/
AVIATION...00Z KGRI TAF. MVFR CONDITIONS TO CONTINUE THROUGH
07Z...WITH VFR CONDITIONS EXPECTED 07Z-21Z...AND ANOTHER ROUND OF
MVFR CONDITIONS POSSIBLE AFTER 21Z. RESTRICTED VISIBILITY TO
AROUND 3SM WILL ALSO BE POSSIBLE IN FOG 02-07Z. THE SURFACE WIND
WILL INTENSIFY FROM THE NORTHWEST TONIGHT...SUSTAINED NEAR 26KTS
AND GUSTING TO NEAR 34KTS 02-07Z. A DIMINISHING SURFACE WIND IS
THEN EXPECTED AT THE TERMINAL THROUGH THE REMAINDER OF THE TAF
PERIOD.
PREV DISCUSSION... /ISSUED 405 PM CST FRI JAN 11 2013/
SHORT TERM...NOW THROUGH SATURDAY
.WINTERS COLD RETURNS TO THE CNTRL PLAINS TONIGHT WITH A PERIOD OF
STRONG WIND GUSTS IN THE TRANSITION...
AN SPS WAS ISSUED AT 2032Z FOR THE BLOWING DUST AND WILL PROBABLY
BE UPDATED BY THE BOTTOM OF THE HOUR.
WIND ADVISORIES CONTINUE AS POSTED. NPW WAS UPDATED/SENT AT 324 PM
TO RAISE ADDITIONAL AWARENESS OF BLOWING DUST OVER KS.
NOW: STRONG COLD FRONT IS SAGGING SE THRU CNTRL NEB. IT WAS LAST
SEEN ON THE LNX 88D AT 1825Z JUST NW OF BBW. THE TIMING TOOL BRINGS
IT INTO GRI BY 2230Z. 992 MB LOW WAS TRACKING ALONG THE KS-NEB
BORDER...S OF WHERE IT WAS FCST 24 HRS AGO.
THE FRONT IS AHEAD OF SCHEDULE SO USED THE RAP FOR SHORT-TERM WINDS.
THE 18Z RAP SUGGESTS IT FINALLY CUTS NE THIS EVNG ACROSS ERN NEB.
BLOWING DUST: A BURST OF 33-41 KT WINDS HAS RESULTED IN A LARGE AREA
OF BLOWING DUST THAT ORIGINATED OVER ERN CO. TIMING TOOL WILL BRING
THIS INTO OUR KS COUNTIES AROUND 445 PM AND IT WILL CONTINUE UNTIL
WIND SHIFT ASSOCIATED WITH COLD FRONTAL PASSAGE.
CONTEMPLATED CANCELLING THE WIND ADVISORY FOR N-CNTRL KS SINCE WINDS
HAVE BEEN WELL BELOW ADVISORY SUSTAINED OR GUSTS. BUT GIVEN MULTIPLE
G40 KTS WITH THAT DUST...HAVE CONTINUED ADVISORY.
A LARGE AREA OF STRATUS IS EXPECTED TO SINK S BEHIND THE FRONT TNGT
IN THE WAKE OF THE DEPARTING LOW. HOW FAR S OVC EXTENDS REMAINS
UNCERTAIN GIVEN DOWNSLOPING WINDS WILL TEND TO BREAK IT UP.
WIND: 3 HR PRES RISES ARE ONLY 3 MB OVER THE NEB PANHANDLE AT 21Z.
THE NAM IS OVER ESTIMATING THIS BY 5 MB AND THE RAP BY 3 MB. THINK
THE TREND IS RIGHT WITH EXPANDING/INCREASING PRES RISES AS THE LOW
ACCELERATES NEWD THIS EVE...BUT THE MAGNITUDE MAY BE OVERDONE.
CONFIDENCE IS ABOVE AVERAGE FOR VERIFYING THE ADVISORY OVER N-CNTRL
KS AHEAD OF THE FRONT. IT/S TAKEN ALL DAY BUT IT WILL VERIFY
22Z-03Z. BEHIND THE FRONT HAVE YET TO SEE ADVISORY LEVEL WINDS
DEVELOP. LOW-LEVELS WILL BECOME UNSTABLE IN CAA THIS EVE AND BUT
THIS APPEARS A MARGINAL WIND EVENT SO VERIFYING NEB WIND ADVISORY IS
BELOW AVERAGE ALONG AND S OF I-80. BEST CHANCE FOR A ONE-TIME 45 MPH
GUST WILL BE N OF THE TRI-CITIES. THE BEST CHANCE FOR VERIFYING
ALONG AND S OF I-80 WILL PROBABLY BE A BRIEF PERIOD OF SUSTAINED
WINDS OF 30 MPH.
TNGT: M/CLOUDY WITH BLUSTERY NW WINDS. SOME FLURRIES OR BRIEF SHSN
WILL OCCUR 6PM-12AM IN PULSE OF CAA. TEMP GUIDANCE WAS IN GOOD
AGREEMENT AND USED THE CONSENSUS OF ALL GUIDANCE WHICH BASICALLY
PUTS TEMPS NEAR NORMAL.
SAT: A MIX OF CLOUDS/SUN. UNSURE HOW MUCH STRATOCU GETS TRAPPED
UNDER FRONTAL INVERSION. HAVE ALREADY INCREASED CLOUDS ABOVE
PREVIOUS GID FCST AND IF NAM BUFKIT IS RIGHT THAN WE WILL BE TOO
LOW ON CLOUD COVER. REGARDLESS...PATCHES JET STREAM CIRRUS WILL
KEEP THE SKY AT LEAST P/CLOUDY. STILL A BLUSTERY NW WIND WITH GUST
UP TO 30 MPH FORENOON. TEMPS ARE NAM 2M TEMPS WHICH IS CLOSE TO
THE PREVIOUS FCST...ABOUT 12F BELOW NORMAL.
LONG TERM...SATURDAY NIGHT THROUGH FRIDAY. THIS WILL LIKELY BE A
DRY PERIOD WITH TEMPERATURES GENERALLY WARMING THROUGH AT LEAST
WEDNESDAY. MORE UNCERTAINTY ENTERS THE PICTURE BY THURSDAY AND
FRIDAY.
SATURDAY NIGHT THROUGH MONDAY...A COLD AREA OF ARCTIC HIGH PRESSURE
WILL BEGIN TO SLIDE INTO THE PLAINS SATURDAY NIGHT INTO SUNDAY AND
REMAIN THROUGH AT LEAST MONDAY. THERE WILL BE A LARGE UPPER TROUGH
SITUATED OVER THE PLAINS BUT ALL OF THE MOISTURE WILL BE AT THE
LEADING EDGE OF THIS TROUGH AND WELL OFF TO OUR EAST. HIGH
TEMPERATURES WILL BE STUCK IN THE 20S ON SUNDAY AND POSSIBLY MONDAY
AS WELL. SOME AREAS THAT ARE COMPLETELY FREE OF SNOW COVER MAY REACH
THE LOWER 30S ON MONDAY.
TUESDAY AND WEDNESDAY...THE 12Z ECMWF PUSHES THE SFC HIGH OFF TO OUR
SOUTH ALLOWING FOR WEST SOUTHWEST DOWNSLOPE SFC WINDS. THE SHALLOW
COLD AIR WILL GRADUALLY MODERATE WITH HIGH TEMPERATURES BACK INTO
THE 30S ON TUESDAY AND PROBABLY 40S BY WEDNESDAY.
THURSDAY THROUGH FRIDAY...THERE IS A SUBSTANTIAL AMOUNT OF MODEL
UNCERTAINTY WITH REGARD TO TEMPERATURES. HOWEVER...THERE IS GOOD
MODEL AGREEMENT IN DRY CONDITIONS. THE ECMWF BRINGS A COLD FRONT
THROUGH WEDNESDAY NIGHT WITH STRONG COLD AIR ADVECTION ON THURSDAY.
THE 850 MB TEMPERATURES THURSDAY EVENING RANGE FROM -15C ON THE 12Z
ECMWF TO 5C ON THE 12Z GFS FOR A SIGNIFICANT 20C DEGREE SPREAD. THE
OFFICIAL FORECAST IS SOMEWHERE IN THE MIDDLE OF THESE TWO MODELS
CALLING FOR ABOVE FREEZING HIGHS IN THE UPPER 30S TO LOWER 40S.
HOWEVER...THESE HIGHS MAY VERY WELL BE TOO WARM. THE ONGOING
STRATOSPHERIC WARMING EVENT WILL LIKELY RESULT IN THE TRANSITION TO
A NEGATIVE ARCTIC OSCILLATION PATTERN...WHICH TENDS TO BRING THE
COLD AIR DOWN OUT OF CANADA INTO THE EASTERN TWO THIRDS OF THE
CONUS. THEREFORE...I WOULD LEAN MORE TOWARDS THE ECWMF AND THE
POSSIBILITY OF COLDER TEMPERATURES THAN WHAT WE ARE OFFICIALLY
CALLING FOR AS THIS BETTER FITS THE -AO PATTERN. IF THE 12Z ECMWF
COLDER TREND CONTINUES...WE WILL NEED TO BE LOWERING OUR THURSDAY
AND FRIDAY HIGH TEMPERATURES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY UNTIL 1 AM CST SATURDAY FOR NEZ039>041-046>049-
060>064-074>077.
KS...WIND ADVISORY UNTIL 10 PM CST THIS EVENING FOR KSZ005-006-
017>019.
&&
$$
0621 PM UPDATE/AVIATION...BRYANT
SHORT TERM...HALBLAUB
LONG TERM...WESELY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
523 PM CST FRI JAN 11 2013
.AVIATION...00Z KGRI TAF. MVFR CONDITIONS TO CONTINUE THROUGH
07Z...WITH VFR CONDITIONS EXPECTED 07Z-21Z...AND ANOTHER ROUND OF
MVFR CONDITIONS POSSIBLE AFTER 21Z. RESTRICTED VISIBILITY TO
AROUND 3SM WILL ALSO BE POSSIBLE IN FOG 02-07Z. THE SURFACE WIND
WILL INTENSIFY FROM THE NORTHWEST TONIGHT...SUSTAINED NEAR 26KTS
AND GUSTING TO NEAR 34KTS 02-07Z. A DIMINISHING SURFACE WIND IS
THEN EXPECTED AT THE TERMINAL THROUGH THE REMAINDER OF THE TAF
PERIOD.
&&
.PREV DISCUSSION... /ISSUED 405 PM CST FRI JAN 11 2013/
SHORT TERM...NOW THROUGH SATURDAY
..WINTERS COLD RETURNS TO THE CNTRL PLAINS TONIGHT WITH A PERIOD OF
STRONG WIND GUSTS IN THE TRANSITION...
AN SPS WAS ISSUED AT 2032Z FOR THE BLOWING DUST AND WILL PROBABLY
BE UPDATED BY THE BOTTOM OF THE HOUR.
WIND ADVISORIES CONTINUE AS POSTED. NPW WAS UPDATED/SENT AT 324 PM
TO RAISE ADDITIONAL AWARENESS OF BLOWING DUST OVER KS.
NOW: STRONG COLD FRONT IS SAGGING SE THRU CNTRL NEB. IT WAS LAST
SEEN ON THE LNX 88D AT 1825Z JUST NW OF BBW. THE TIMING TOOL BRINGS
IT INTO GRI BY 2230Z. 992 MB LOW WAS TRACKING ALONG THE KS-NEB
BORDER...S OF WHERE IT WAS FCST 24 HRS AGO.
THE FRONT IS AHEAD OF SCHEDULE SO USED THE RAP FOR SHORT-TERM WINDS.
THE 18Z RAP SUGGESTS IT FINALLY CUTS NE THIS EVNG ACROSS ERN NEB.
BLOWING DUST: A BURST OF 33-41 KT WINDS HAS RESULTED IN A LARGE AREA
OF BLOWING DUST THAT ORIGINATED OVER ERN CO. TIMING TOOL WILL BRING
THIS INTO OUR KS COUNTIES AROUND 445 PM AND IT WILL CONTINUE UNTIL
WIND SHIFT ASSOCIATED WITH COLD FRONTAL PASSAGE.
CONTEMPLATED CANCELLING THE WIND ADVISORY FOR N-CNTRL KS SINCE WINDS
HAVE BEEN WELL BELOW ADVISORY SUSTAINED OR GUSTS. BUT GIVEN MULTIPLE
G40 KTS WITH THAT DUST...HAVE CONTINUED ADVISORY.
A LARGE AREA OF STRATUS IS EXPECTED TO SINK S BEHIND THE FRONT TNGT
IN THE WAKE OF THE DEPARTING LOW. HOW FAR S OVC EXTENDS REMAINS
UNCERTAIN GIVEN DOWNSLOPING WINDS WILL TEND TO BREAK IT UP.
WIND: 3 HR PRES RISES ARE ONLY 3 MB OVER THE NEB PANHANDLE AT 21Z.
THE NAM IS OVER ESTIMATING THIS BY 5 MB AND THE RAP BY 3 MB. THINK
THE TREND IS RIGHT WITH EXPANDING/INCREASING PRES RISES AS THE LOW
ACCELERATES NEWD THIS EVE...BUT THE MAGNITUDE MAY BE OVERDONE.
CONFIDENCE IS ABOVE AVERAGE FOR VERIFYING THE ADVISORY OVER N-CNTRL
KS AHEAD OF THE FRONT. IT/S TAKEN ALL DAY BUT IT WILL VERIFY
22Z-03Z. BEHIND THE FRONT HAVE YET TO SEE ADVISORY LEVEL WINDS
DEVELOP. LOW-LEVELS WILL BECOME UNSTABLE IN CAA THIS EVE AND BUT
THIS APPEARS A MARGINAL WIND EVENT SO VERIFYING NEB WIND ADVISORY IS
BELOW AVERAGE ALONG AND S OF I-80. BEST CHANCE FOR A ONE-TIME 45 MPH
GUST WILL BE N OF THE TRI-CITIES. THE BEST CHANCE FOR VERIFYING
ALONG AND S OF I-80 WILL PROBABLY BE A BRIEF PERIOD OF SUSTAINED
WINDS OF 30 MPH.
TNGT: M/CLOUDY WITH BLUSTERY NW WINDS. SOME FLURRIES OR BRIEF SHSN
WILL OCCUR 6PM-12AM IN PULSE OF CAA. TEMP GUIDANCE WAS IN GOOD
AGREEMENT AND USED THE CONSENSUS OF ALL GUIDANCE WHICH BASICALLY
PUTS TEMPS NEAR NORMAL.
SAT: A MIX OF CLOUDS/SUN. UNSURE HOW MUCH STRATOCU GETS TRAPPED
UNDER FRONTAL INVERSION. HAVE ALREADY INCREASED CLOUDS ABOVE
PREVIOUS GID FCST AND IF NAM BUFKIT IS RIGHT THAN WE WILL BE TOO
LOW ON CLOUD COVER. REGARDLESS...PATCHES JET STREAM CIRRUS WILL
KEEP THE SKY AT LEAST P/CLOUDY. STILL A BLUSTERY NW WIND WITH GUST
UP TO 30 MPH FORENOON. TEMPS ARE NAM 2M TEMPS WHICH IS CLOSE TO
THE PREVIOUS FCST...ABOUT 12F BELOW NORMAL.
LONG TERM...SATURDAY NIGHT THROUGH FRIDAY. THIS WILL LIKELY BE A
DRY PERIOD WITH TEMPERATURES GENERALLY WARMING THROUGH AT LEAST
WEDNESDAY. MORE UNCERTAINTY ENTERS THE PICTURE BY THURSDAY AND
FRIDAY.
SATURDAY NIGHT THROUGH MONDAY...A COLD AREA OF ARCTIC HIGH PRESSURE
WILL BEGIN TO SLIDE INTO THE PLAINS SATURDAY NIGHT INTO SUNDAY AND
REMAIN THROUGH AT LEAST MONDAY. THERE WILL BE A LARGE UPPER TROUGH
SITUATED OVER THE PLAINS BUT ALL OF THE MOISTURE WILL BE AT THE
LEADING EDGE OF THIS TROUGH AND WELL OFF TO OUR EAST. HIGH
TEMPERATURES WILL BE STUCK IN THE 20S ON SUNDAY AND POSSIBLY MONDAY
AS WELL. SOME AREAS THAT ARE COMPLETELY FREE OF SNOW COVER MAY REACH
THE LOWER 30S ON MONDAY.
TUESDAY AND WEDNESDAY...THE 12Z ECMWF PUSHES THE SFC HIGH OFF TO OUR
SOUTH ALLOWING FOR WEST SOUTHWEST DOWNSLOPE SFC WINDS. THE SHALLOW
COLD AIR WILL GRADUALLY MODERATE WITH HIGH TEMPERATURES BACK INTO
THE 30S ON TUESDAY AND PROBABLY 40S BY WEDNESDAY.
THURSDAY THROUGH FRIDAY...THERE IS A SUBSTANTIAL AMOUNT OF MODEL
UNCERTAINTY WITH REGARD TO TEMPERATURES. HOWEVER...THERE IS GOOD
MODEL AGREEMENT IN DRY CONDITIONS. THE ECMWF BRINGS A COLD FRONT
THROUGH WEDNESDAY NIGHT WITH STRONG COLD AIR ADVECTION ON THURSDAY.
THE 850 MB TEMPERATURES THURSDAY EVENING RANGE FROM -15C ON THE 12Z
ECMWF TO 5C ON THE 12Z GFS FOR A SIGNIFICANT 20C DEGREE SPREAD. THE
OFFICIAL FORECAST IS SOMEWHERE IN THE MIDDLE OF THESE TWO MODELS
CALLING FOR ABOVE FREEZING HIGHS IN THE UPPER 30S TO LOWER 40S.
HOWEVER...THESE HIGHS MAY VERY WELL BE TOO WARM. THE ONGOING
STRATOSPHERIC WARMING EVENT WILL LIKELY RESULT IN THE TRANSITION TO
A NEGATIVE ARCTIC OSCILLATION PATTERN...WHICH TENDS TO BRING THE
COLD AIR DOWN OUT OF CANADA INTO THE EASTERN TWO THIRDS OF THE
CONUS. THEREFORE...I WOULD LEAN MORE TOWARDS THE ECWMF AND THE
POSSIBILITY OF COLDER TEMPERATURES THAN WHAT WE ARE OFFICIALLY
CALLING FOR AS THIS BETTER FITS THE -AO PATTERN. IF THE 12Z ECMWF
COLDER TREND CONTINUES...WE WILL NEED TO BE LOWERING OUR THURSDAY
AND FRIDAY HIGH TEMPERATURES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY UNTIL 1 AM CST SATURDAY FOR NEZ039>041-046>049-
060>064-074>077.
KS...WIND ADVISORY UNTIL 10 PM CST THIS EVENING FOR KSZ005-006-
017>019.
&&
$$
AVIATION...BRYANT
SHORT TERM...HALBLAUB
LONG TERM...WESELY
AREA FORECAST DISCUSSION
NWS BISMARCK ND
548 AM CST THU JAN 10 2013
.DISCUSSION...
QUICK UPDATE FOR MORNING WIND AND TEMPERATURE TRENDS. AS OF 1145
UTC...THE SOUTH CENTRAL HAS SEEN SOUTHERLY WINDS INCREASE OVER THE
PAST ONE TO TWO HOURS WITH GUSTS OF 20 TO 30 KTS OBSERVED. THIS IS
MIXING DOWN TEMPERATURES FROM THE INVERSION WITH 37 DEGREES
OBSERVED AT THE NWS OFFICE AT THE AIRPORT...37 AT LINTON AND 36 AT
OAKES. BLENDED THE LATEST HRRR RUNS FOR WINDS THROUGH 18 UTC WHICH
ARE CAPTURING THIS MIXING AND BLENDED TO THE WARMEST TEMPERATURE
GUIDANCE TODAY...WHICH IS THE 00 UTC ECMWF. THUS...HAVE RAISED
HIGHS INTO LOW TO MID 40S FOR THE I-94 CORRIDOR IN LIGHT OF THE
CURRENT MIXED TEMPERATURES PRIOR TO INSOLATION.
&&
.AVIATION...
AT 545 AM CST THURSDAY...LOW PRESSURE WAS OVER SOUTHERN
SASKATCHEWAN WITH A COLD FRONT EXTENDING SOUTHWEST INTO NORTHWEST
MONTANA. A BROAD AREA OF VFR CONDITIONS EXTENDED ACROSS WEST AND
CENTRAL NORTH DAKOTA. AS THE SURFACE COLD FRONT ACROSS NORTHERN
MONTANA APPROACHES WESTERN NORTH DAKOTA AFTER 21Z/3 PM CST
THURSDAY...MVFR CONDITIONS WILL DEVELOP FROM KMOT TO KISN TO KDIK
TO KBIS...AND EVENTUALLY KJMS AFTER 00Z. A SIGNIFICANT WINTER
STORM WILL BRING MULTIPLE HAZARDS TO AVIATION ACROSS WEST AND
CENTRAL NORTH DAKOTA AFTER 06Z/FRIDAY.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING
FOR NDZ001>005-009>013-017>023-025-031>037-040>048-050-051.
&&
$$
UPDATE...AYD
AVIATION...WAA
AREA FORECAST DISCUSSION
NWS NORMAN OK
108 PM CST THU JAN 10 2013
.UPDATE...
UPDATED AGAIN AS SHOWERS CONTINUE TO FORM NEAR THE CIRCULATION
CENTER. RAP AND LOCAL WRF SHOW THAT THESE SHOWERS WILL PERSIST
THIS AFTERNOON AND LIFT NORTH/NORTHEAST. HAVE INCREASED POPS
SIGNIFICANTLY AND GONE WITH AREAL WORDING NEAR AND NORTH/NORTHEAST
OF CURRENT DEVELOPMENT.
&&
.PREV DISCUSSION... /ISSUED 1242 PM CST THU JAN 10 2013/
UPDATE...
UPDATING THE PACKAGE TO REMOVE SOME OF THE TEMPORAL WORDING AND
TO ACCOUNT FOR CURRENT TRENDS IN PRECIPITATION AND CLOUDS. THE
MAIN BAND OF PRECIPITATION HAD MOVED OUT OF THE AREA... ALTHOUGH
SOME DRIZZLE AND/OR LIGHT RAIN HAS REDEVELOPED NEAR THE UPPER
LOW. SOME DRIER AIR IS ALSO ENTRAINING INTO THE CIRCULATION AND
ALLOWING SOME PARTIAL CLEARING FROM SOUTHEAST INTO CENTRAL
OKLAHOMA.
PREV DISCUSSION... /ISSUED 1139 AM CST THU JAN 10 2013/
AVIATION...
IFR TO BRIEF LIFR DUE TO LOW CIGS AND FOG WILL CONTINUE OVER MANY
OF THE TERMINALS THROUGH THE EARLY AFTERNOON HOURS. CONDITIONS
WILL SLOWLY IMPROVE LATER THIS AFTERNOON AND EARLY THIS
EVENING...BUT SOME TEMPORARY FOG MAY RETURN AROUND 04-07Z LATE
TONIGHT. FLIGHT CONDITIONS WILL IMPROVE AFTER THIS WITH VFR LIKELY
RETURNING TO MOST OF THE TERMINALS BEFORE SUNRISE.
&&
.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK 56 43 66 39 / 50 10 10 10
HOBART OK 53 39 65 34 / 30 10 10 10
WICHITA FALLS TX 59 43 71 38 / 20 10 10 10
GAGE OK 50 38 62 24 / 20 10 10 10
PONCA CITY OK 56 42 67 29 / 30 10 10 10
DURANT OK 61 45 68 50 / 20 10 10 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&
$$
99/99
AREA FORECAST DISCUSSION
NWS MEDFORD OR
857 AM PST THU JAN 10 2013
.DISCUSSION...CURRENT WATER VAPOR IMAGE SHOWS ANOTHER DISTURBANCE
MOVING TOWARDS THE FORECAST AREA. THIS COULD BE SIGNIFICANT ENOUGH
TO BRING A FEW MODERATE TO HEAVY SHOWERS TO THE AREA THIS MORNING
THROUGH LATE THIS AFTERNOON. SNOW LEVELS WILL AVERAGE AROUND 1500
FEET THIS AFTERNOON...BUT COULD TEMPORALLY LOWER BETWEEN 500 AND
1000 FEET IN LOCATIONS THAT GET CAUGHT UNDER HEAVIER SHOWERS
RESULTING IN TEMPORARY ACCUMULATION OF A TRACE TO HALF INCH IN
THE VALLEYS AND 1 TO 3 INCHES ABOVE 2000 FEET. THIS IS BEING
SUPPORTED BY THE FACT THAT WEBCAMS IN REEDSPORT AND A FEW OTHER
LOCATIONS BELOW 1000 FEET ARE SHOWING MODERATE SNOWFALL WITH SNOW
ACCUMULATING ON GRASSY AREAS AND ROADS.
CURRENT WINTER WEATHER ADVISORIES WEST OF THE CASCADES END AT 1
PM PST AND WE`LL TAKE A CLOSER LOOK AND SEE IF THE ENDING TIME
NEEDS TO BE EXTENDED LATER. -PETRUCELLI
&&
.AVIATION...AVIATION...A VERY COLD AND SHOWERY AIR MASS WILL PERSIST
WITH A SERIES OF DISTURBANCES THROUGH FRIDAY. THIS WILL RESULT IN
PERIODS OF SNOW SHOWERS...MOST NUMEROUS IN SOUTHWEST OREGON.
THUNDERSTORMS ARE POSSIBLE ALONG THE COAST TONIGHT INTO THIS
MORNING. ADDITIONALLY...FREQUENT MOUNTAIN OBSCURATIONS WITH
VISIBILITY REDUCED IN SNOW SHOWERS CAN BE EXPECTED THROUGH TODAY.
SKY CONDITION TODAY WILL BE VARIABLE DUE TO THE SHOWERY NATURE OF
THE WEATHER...INCLUDING IFR DURING MORE INTENSE SNOW SHOWERS BUT
PREDOMINANTLY MVFR CEILINGS. SNOW SHOWERS WILL BE MORE NUMEROUS AT
NORTHWEST FACING SLOPES SUCH AS PARTS OF THE UMPQUA DIVIDE AND
SISKIYOU SUMMIT. THE FREEZING LEVEL WILL REMAIN BETWEEN 1000 AND
2000 FT MSL THROUGH FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 348 AM PST THU JAN 10 2013/
SHORT TERM...AN UPPER TROUGH WILL REMAIN OVER THE REGION TODAY
WHILE A COUPLE SHORTWAVES MOVE THROUGH THE AREA BRINGING SCATTERED
TO WIDESPREAD SHOWERS INTO THE AREA. THE UPPER TROUGH GRADUALLY
SHIFTS EASTWARD TONIGHT AND FRIDAY WITH A RIDGE OFFSHORE NUDGING
INTO THE AREA FRIDAY AND SATURDAY. HOWEVER ADDITIONAL SHORTWAVE
DISTURBANCES WILL BRING THE POTENTIAL FOR MORE PRECIPITATION
THROUGH SATURDAY NIGHT.
A LARGE BATCH OF SHOWERS IS VISIBLE ON SATELLITE AND MOVING INTO
WESTERN PORTIONS OF THE AREA THIS MORNING. SNOW LEVELS ARE AROUND
1000 FEET THIS MORNING. LIGHT ACCUMULATIONS IN SHOWERS ARE
EXPECTED IN WEST SIDE VALLEYS AS WELL AS THE MOUNTAINS THIS
MORNING. ALSO A SECOND SHORTWAVE IS VISIBLE JUST OFF ASTORIA AND IS
EXPECTED TO MOVE INTO NORTHERN PORTIONS OF THE CWA IN THE MID TO
LATE MORNING.
THE RUC MODEL SEEMS TO HAVE THE BEST HANDLE ON THE TRACK OF THE
SHORTWAVES AND PRECIPITATION. IT SHOWS SHOWERS INCREASING EARLY
THIS MORNING FROM THE CASCADES WEST. THE SECOND SHORTWAVE HAS A
WEAK SURFACE LOW ASSOCIATED WITH IT. THIS LOW IS FORECAST TO TRACK
SOUTH-SOUTHEAST MOVING INLAND AND INTO DOUGLAS COUNTY IN THE LATE
MORNING...THEN TRACKING EAST OF THE CASCADES IN THE AFTERNOON. AS
THIS FEATURE MOVES INLAND...EXPECT ADDITIONAL SHOWERS FROM THE
CASCADES WEST TO CONTINUE INTO THE AFTERNOON AS WELL AS SHOWERS
INCREASING EAST OF THE CASCADES DURING THE AFTERNOON. HAVE
EXTENDED THE WINTER WEATHER ADVISORIES THROUGH NOON DUE TO THE
EXPECTED CONTINUATION OF SHOWERS WITH THIS SECOND DISTURBANCE.
ALTHOUGH SHOWERS WILL CONTINUE THROUGH THE AFTERNOON...SNOW LEVELS
WILL RISE SLIGHTLY AND DAYTIME WARMING IS EXPECTED TO ALLOW LITTLE
ADDITIONAL SNOW IN THE VALLEYS. HIGHER TERRAIN WILL CONTINUE TO
SEE LIGHT ADDITIONAL SNOW ACCUMULATIONS THOUGH. THE RUC MODEL
INDICATES A POTENTIAL FOR SOME LIGHT TO MODERATE SNOW
ACCUMULATIONS OVER THE SOUTHERN OREGON CASCADES AND INTO NORTHERN
KLAMATH COUNTY. IF SNOW SHOWERS BECOME WIDESPREAD...MAY NEED TO ADD
OR EXTEND THE WINTER WEATHER ADVISORIES FOR THESE AREAS.
CURRENTLY...CONFIDENCE IN LOW IN THE HOW WIDESPREAD AND HEAVY
AFTERNOON SHOWERS WILL BE.
AREAS OF LIGHT SHOWERS ARE EXPECTED TO LINGER IN TO THE EVENING. OF
NOTE IS THE RUC SHOWS SHOWERS DECREASING FROM NORTH TO SOUTH OVER
THE AREA DURING THE EVENING.
THE UPPER TROUGH GRADUALLY SHIFTS EAST THURSDAY NIGHT AND FRIDAY.
HOWEVER ADDITIONAL DISTURBANCES ON THE BACKSIDE OF THE TROUGH ARE
FORECAST TO BRING ADDITIONAL LIGHT SHOWERS...ESPECIALLY FROM THE
CASCADES WEST THURSDAY NIGHT AND FRIDAY. THEN MODELS SHOW A
BRIEF BREAK IN THE PATTERN FRIDAY EVENING AS A RIDGE OFFSHORE
NUDGES INTO THE PACNW COAST.
ON SATURDAY...MODELS HAVE SHOWN VARIABILITY WITH A COUPLE SHORTWAVES
MOVING DOWN FROM THE NORTH AROUND THE RIDGE. THE GFS AND NAM ARE
STRONGER WITH THESE DISTURBANCES THAN THE ECMWF...ESPECIALLY WITH
THE SECOND SHORTWAVE SATURDAY EVENING AND NIGHT. BEHIND THESE
DISTURBANCES EXPECT NORTHERLY FLOW TO BRING VERY COLD TEMPERATURES
SUNDAY MORNING...ESPECIALLY EAST OF THE CASCADES. COLD
TEMPERATURES ARE FORECAST TO CONTINUE INTO MONDAY.
PREV EXTENDED DISCUSSION... /ISSUED 245 PM PST WED JAN 9 2013/
EXTENDED TERM...SUNDAY MORNING THROUGH WEDNESDAY NIGHT...
THE LONG TERM FORECAST IS RATHER QUIET...ONCE THE WEEKEND SYSTEM
MAKES ITS EXIT OUT OF THE AREA. THE SHORTWAVE THAT IS EXPECTED TO
TRAVERSE THE NORTHERLY FLOW OVER THE REGION SATURDAY NIGHT AND
SUNDAY MORNING WILL EXIT TO THE SOUTH BY SUNDAY NIGHT...AND WITH IT
SO WILL PRECIPITATION CHANCES. WHAT PRECIPITATION THAT DOES FALL
DURING THE DAY SUNDAY WILL BE RELATIVELY LIGHT...AND WITH SNOW
LEVELS REMAINING ABOVE 2500 TO 3000 FEET...ANY IMPACTS WILL BE
CONFINED TO HIGHER ELEVATIONS.
ONCE THE SHORTWAVE FULLY EXITS THE AREA...HIGH AMPLITUDE TOWARDS THE
WEST COAST. THIS WILL PLACE THE FORECAST AREA UNDER THE EASTERN
PERIPHERY OF THE RIDGE AND UNDER NORTHERLY FLOW...BUT THE MAIN BELT
OF WESTERLIES WILL KEEP ANY SHORTWAVES WELL TO THE EAST THROUGHOUT
THE REST OF THE TERM. WITH THE CLEARER SKIES...THE USUAL SUSPECTS
WILL ARISE. THE FIRST IS THE THERMAL TROUGH...WHICH WILL PRODUCE
GUSTY WINDS ALONG RIDGE LINES ABOVE 5000 FEET. THE SECOND WILL BE
PERSISTENT MORNING FOG IN THE VALLEYS. LOW TEMPERATURES WILL STILL
HOVER AT OR BELOW FREEZING WITHIN MANY OF THE VALLEYS...SO FREEZING
FOG MAY BECOME AN ISSUE...AS ROADS AND OTHER SURFACES COULD BECOME
SLICK. OTHERWISE...EXPECT CLEARER SKIES...WITH TEMPERATURES RISING
TO NEAR OR EVEN SLIGHTLY ABOVE SEASONAL NORMALS BY MIDWEEK. -BPN
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ027-028.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1000 FEET FOR
FOR ORZ021-022.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1000 FEET FOR
FOR ORZ023.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ025.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ024-026.
CA...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR CAZ081>083.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1500 FEET FOR
FOR CAZ080.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 1 PM THIS AFTERNOON TO 7 AM
PST FRIDAY FOR PZZ350-356.
HAZARDOUS SEAS WARNING FROM 1 PM THIS AFTERNOON TO 4 AM PST
FRIDAY FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
AFTERNOON FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 AM PST FRIDAY FOR
PZZ370-376.
HAZARDOUS SEAS WARNING UNTIL 4 AM PST FRIDAY FOR PZZ370-376.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST THIS
MORNING FOR PZZ370-376.
$$
AREA FORECAST DISCUSSION
NWS MEDFORD OR
348 AM PST THU JAN 10 2013
.SHORT TERM...AN UPPER TROUGH WILL REMAIN OVER THE REGION TODAY
WHILE A COUPLE SHORTWAVES MOVE THROUGH THE AREA BRINGING SCATTERED
TO WIDESPREAD SHOWERS INTO THE AREA. THE UPPER TROUGH GRADUALLY
SHIFTS EASTWARD TONIGHT AND FRIDAY WITH A RIDGE OFFSHORE NUDGING
INTO THE AREA FRIDAY AND SATURDAY. HOWEVER ADDITIONAL SHORTWAVE
DISTURBANCES WILL BRING THE POTENTIAL FOR MORE PRECIPITATION
THROUGH SATURDAY NIGHT.
A LARGE BATCH OF SHOWERS IS VISIBLE ON SATELLITE AND MOVING INTO
WESTERN PORTIONS OF THE AREA THIS MORNING. SNOW LEVELS ARE AROUND
1000 FEET THIS MORNING. LIGHT ACCUMULATIONS IN SHOWERS ARE
EXPECTED IN WEST SIDE VALLEYS AS WELL AS THE MOUNTAINS THIS
MORNING. ALSO A SECOND SHORTWAVE IS VISIBLE JUST OFF ASTORIA AND IS
EXPECTED TO MOVE INTO NORTHERN PORTIONS OF THE CWA IN THE MID TO
LATE MORNING.
THE RUC MODEL SEEMS TO HAVE THE BEST HANDLE ON THE TRACK OF THE
SHORTWAVES AND PRECIPITATION. IT SHOWS SHOWERS INCREASING EARLY
THIS MORNING FROM THE CASCADES WEST. THE SECOND SHORTWAVE HAS A
WEAK SURFACE LOW ASSOCIATED WITH IT. THIS LOW IS FORECAST TO TRACK
SOUTH-SOUTHEAST MOVING INLAND AND INTO DOUGLAS COUNTY IN THE LATE
MORNING...THEN TRACKING EAST OF THE CASCADES IN THE AFTERNOON. AS
THIS FEATURE MOVES INLAND...EXPECT ADDITIONAL SHOWERS FROM THE
CASCADES WEST TO CONTINUE INTO THE AFTERNOON AS WELL AS SHOWERS
INCREASING EAST OF THE CASCADES DURING THE AFTERNOON. HAVE
EXTENDED THE WINTER WEATHER ADVISORIES THROUGH NOON DUE TO THE
EXPECTED CONTINUATION OF SHOWERS WITH THIS SECOND DISTURBANCE.
ALTHOUGH SHOWERS WILL CONTINUE THROUGH THE AFTERNOON...SNOW LEVELS
WILL RISE SLIGHTLY AND DAYTIME WARMING IS EXPECTED TO ALLOW LITTLE
ADDITIONAL SNOW IN THE VALLEYS. HIGHER TERRAIN WILL CONTINUE TO
SEE LIGHT ADDITIONAL SNOW ACCUMULATIONS THOUGH. THE RUC MODEL
INDICATES A POTENTIAL FOR SOME LIGHT TO MODERATE SNOW
ACCUMULATIONS OVER THE SOUTHERN OREGON CASCADES AND INTO NORTHERN
KLAMATH COUNTY. IF SNOW SHOWERS BECOME WIDESPREAD...MAY NEED TO ADD
OR EXTEND THE WINTER WEATHER ADVISORIES FOR THESE AREAS.
CURRENTLY...CONFIDENCE IN LOW IN THE HOW WIDESPREAD AND HEAVY
AFTERNOON SHOWERS WILL BE.
AREAS OF LIGHT SHOWERS ARE EXPECTED TO LINGER IN TO THE EVENING. OF
NOTE IS THE RUC SHOWS SHOWERS DECREASING FROM NORTH TO SOUTH OVER
THE AREA DURING THE EVENING.
THE UPPER TROUGH GRADUALLY SHIFTS EAST THURSDAY NIGHT AND FRIDAY.
HOWEVER ADDITIONAL DISTURBANCES ON THE BACKSIDE OF THE TROUGH ARE
FORECAST TO BRING ADDITIONAL LIGHT SHOWERS...ESPECIALLY FROM THE
CASCADES WEST THURSDAY NIGHT AND FRIDAY. THEN MODELS SHOW A
BRIEF BREAK IN THE PATTERN FRIDAY EVENING AS A RIDGE OFFSHORE
NUDGES INTO THE PACNW COAST.
ON SATURDAY...MODELS HAVE SHOWN VARIABILITY WITH A COUPLE SHORTWAVES
MOVING DOWN FROM THE NORTH AROUND THE RIDGE. THE GFS AND NAM ARE
STRONGER WITH THESE DISTURBANCES THAN THE ECMWF...ESPECIALLY WITH
THE SECOND SHORTWAVE SATURDAY EVENING AND NIGHT. BEHIND THESE
DISTURBANCES EXPECT NORTHERLY FLOW TO BRING VERY COLD TEMPERATURES
SUNDAY MORNING...ESPECIALLY EAST OF THE CASCADES. COLD
TEMPERATURES ARE FORECAST TO CONTINUE INTO MONDAY.
&&
.AVIATION...A VERY COLD AND SHOWERY AIR MASS WILL PERSIST
WITH A SERIES OF DISTURBANCES THROUGH FRIDAY. THIS WILL RESULT IN
PERIODS OF SNOW SHOWERS...MOST NUMEROUS IN SOUTHWEST OREGON.
THUNDERSTORMS ARE POSSIBLE ALONG THE COAST TONIGHT INTO THIS
MORNING. ADDITIONALLY...FREQUENT MOUNTAIN OBSCURATIONS WITH
VISIBILITY REDUCED IN SNOW SHOWERS CAN BE EXPECTED THROUGH TODAY.
SKY CONDITION TODAY WILL BE VARIABLE DUE TO THE SHOWERY NATURE OF
THE WEATHER...INCLUDING IFR DURING MORE INTENSE SNOW SHOWERS BUT
PREDOMINANTLY MVFR CEILINGS. SNOW SHOWERS WILL BE MORE NUMEROUS AT
NORTHWEST FACING SLOPES SUCH AS PARTS OF THE UMPQUA DIVIDE AND
SISKIYOU SUMMIT. THE FREEZING LEVEL WILL REMAIN BETWEEN 1000 AND
2000 FT MSL THROUGH FRIDAY. SK
&&
.PREV EXTENDED DISCUSSION... /ISSUED 245 PM PST WED JAN 9 2013/
.EXTENDED TERM...SUNDAY MORNING THROUGH WEDNESDAY NIGHT...
.THE LONG TERM FORECAST IS RATHER QUIET...ONCE THE WEEKEND SYSTEM
MAKES ITS EXIT OUT OF THE AREA. THE SHORTWAVE THAT IS EXPECTED TO
TRAVERSE THE NORTHERLY FLOW OVER THE REGION SATURDAY NIGHT AND
SUNDAY MORNING WILL EXIT TO THE SOUTH BY SUNDAY NIGHT...AND WITH IT
SO WILL PRECIPITATION CHANCES. WHAT PRECIPITATION THAT DOES FALL
DURING THE DAY SUNDAY WILL BE RELATIVELY LIGHT...AND WITH SNOW
LEVELS REMAINING ABOVE 2500 TO 3000 FEET...ANY IMPACTS WILL BE
CONFINED TO HIGHER ELEVATIONS.
ONCE THE SHORTWAVE FULLY EXITS THE AREA...HIGH AMPLITUDE TOWARDS THE
WEST COAST. THIS WILL PLACE THE FORECAST AREA UNDER THE EASTERN
PERIPHERY OF THE RIDGE AND UNDER NORTHERLY FLOW...BUT THE MAIN BELT
OF WESTERLIES WILL KEEP ANY SHORTWAVES WELL TO THE EAST THROUGHOUT
THE REST OF THE TERM. WITH THE CLEARER SKIES...THE USUAL SUSPECTS
WILL ARISE. THE FIRST IS THE THERMAL TROUGH...WHICH WILL PRODUCE
GUSTY WINDS ALONG RIDGE LINES ABOVE 5000 FEET. THE SECOND WILL BE
PERSISTENT MORNING FOG IN THE VALLEYS. LOW TEMPERATURES WILL STILL
HOVER AT OR BELOW FREEZING WITHIN MANY OF THE VALLEYS...SO FREEZING
FOG MAY BECOME AN ISSUE...AS ROADS AND OTHER SURFACES COULD BECOME
SLICK. OTHERWISE...EXPECT CLEARER SKIES...WITH TEMPERATURES RISING
TO NEAR OR EVEN SLIGHTLY ABOVE SEASONAL NORMALS BY MIDWEEK. -BPN
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ027-028.
FROST ADVISORY UNTIL 8 AM PST THIS MORNING FOR ORZ021-022.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1000 FEET FOR
FOR ORZ021-022.
FREEZE WARNING UNTIL 8 AM PST THIS MORNING FOR ORZ021-022.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE 1000 FEET FOR
FOR ORZ023.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ025.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR ORZ024-026.
CA...WINTER WEATHER ADVISORY UNTIL NOON PST TODAY FOR
CAZ081>083.
WINTER WEATHER ADVISORY UNTIL NOON PST TODAY ABOVE
1500 FEET FOR FOR CAZ080.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 1 PM THIS
AFTERNOON TO 7 AM PST FRIDAY FOR PZZ350-356.
HAZARDOUS SEAS WARNING FROM 1 PM THIS AFTERNOON TO 4 AM PST
FRIDAY FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 1 PM PST THIS
AFTERNOON FOR PZZ350-356.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 7 AM PST FRIDAY FOR
PZZ370-376.
HAZARDOUS SEAS WARNING FROM 10 AM THIS MORNING TO 4 AM PST
FRIDAY FOR PZZ370-376.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM PST THIS
MORNING FOR PZZ370-376.
$$
CC
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
936 AM EST THU JAN 10 2013
.DISCUSSION...STARTING OUT GENERALLY DRY ACROSS THE REGION THIS
MORNING IN SPITE OF A VERY MOIST AIRMASS FROM MIDDLE TN EASTWARD
INTO MAINLY THE SW HALF OF EAST TN. THE 12Z OHX SOUNDING HAD
PRECIPITABLE WATER (PW) VALUE OF JUST OVER 1.35 INCHES (300 PERCENT
OF NORMAL). 12Z RNK SOUNDING MUCH DRIER WITH LESS THAN 1/2 INCH PW.
12Z UPPER PLOTS SHOW A LIGHT SOUTHERLY FLOW AT 850 MB LEVEL...SO A
BIT OF DOWNSLOPING IS LIKELY AFFECTING PARTS OF NE TN AND SW VA.
ANOTHER FACTOR FOR LACK OF RAIN THIS MORNING IN OUR AREA MAY BE THE
STRONG CONVECTION ALREADY OCCURRING OVER THE LOWER MS VALLEY REGION.
LATEST RUC MODEL RUN AND SREF ARE ONLY SHOWING SOME SCATTERED AREAS
OF RAIN DEVELOPING OVER OUR WRN MOST COUNTIES LATER TODAY. THUS...
PLAN TO DO A MID MORNING UPDATE TO LOWER RAIN CHANCES.
MAX TEMP FORECAST IS PROBABLY ON TRACK...ALTHO WARM FRONT IS STILL
TO OUR SOUTH. 14Z TEMPS WERE VERY MILD AND ALREADY ABOVE SEASONAL
HIGHS FOR MID JANUARY...SO ANY BREAKS OF SUNSHINE OR DOWNSLOPING
SHOULD SEND HIGHS INTO THE UPPER 50S TO MID 60S.
&&
.PRELIMINARY POINT TEMPS/POPS...
CHATTANOOGA AIRPORT, TN 65 54 68 57 72 / 60 60 60 30 30
KNOXVILLE MCGHEE TYSON AIRPORT, TN 63 50 67 55 71 / 50 50 60 30 30
OAK RIDGE, TN 63 50 66 55 71 / 60 50 60 20 30
TRI CITIES AIRPORT, TN 62 43 63 49 69 / 30 30 40 20 20
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...NONE.
TN...NONE.
VA...NONE.
&&
$$
TG
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1151 PM CST WED JAN 9 2013
.UPDATE...FOR 06Z TAFS
&&
.AVIATION...
A WARM FRONT WELL SOUTH OF THE REGION AT 06Z WILL STENGTHEN AND
MOVE NORTH DURING THIS PERIOD AS LOW PRESSURE MOVES FROM TX TOWARD
MID MS VALLEY. LOW CLOUDS AND SOME FOG EXPECTED AT ALL 3 TAF SITES
FOR REST OF TONIGHT AND MUCH OF THURSDAY. IN ADDITION...AREAS OF
LIGHT TO MODERATE RAIN WILL IMPACT MAINLY KBNA AND KCKV THE REST
OF TONIGHT AND INTO EARLY THURSDAY AHEAD OF THE WARM FRONT. WINDS
WILL INCREASE AND BECOME GUSTY THURSDAY AFTERNOON/NIGHT AS
SIGNIFICANT SFC PRESSURE FALLS OCCUR TO OUR NORTHWEST.
&&
.PREV DISCUSSION... /ISSUED 1006 PM CST WED JAN 9 2013/
UPDATE...CURRENT FORECAST FOR MIDDLE TENNESSEE IS HOLDING UP WELL
FOR THE MOST PART. RAIN CONTINUES TO PROPAGATE NORTHWARD WHILE
WEAKENING. LATEST HRRR SHOWS MAINLY LIGHT PRECIPITATION CONTINUING
OVERNIGHT. GIVEN THE CURRENT RADAR TREND, WILL UPDATE THE FORECAST
SHORTLY TO REMOVE THE SLIGHT CHANCE OF THUNDER WE HAVE RUNNING IN
THE OVERNIGHT PERIOD. BUT NO OTHER CHANGES ARE PLANNED AT THIS
TIME.
PREV DISCUSSION... /ISSUED 614 PM CST WED JAN 9 2013/
UPDATE...FOR 00Z AVIATION FORECAST
AVIATION...
THIS 24 HOUR PERIOD WILL BE DOMINATED BY PLENTY OF MOISTURE THANKS
TO STRONG H5 LOW REMAINING WELL TO OUR WEST. THE LOW HAS BEEN OVER
THE TX BIG BEND LATELY BUT SHOULD START MOVING NORTHEAST TOWARD
OKLAHOMA OVERNIGHT AND THURSDAY.
EXTENSIVE CLOUDS WILL CONTINUE ACROSS THE REGION THROUGH AT LEAST
00Z FRIDAY...WITH WIDESPREAD MVRF/IFR CONDITIONS AND POCKETS OF
LIFR. VSBYS WILL FREQUENTLY BE 4SM OR LESS IN FOG AND LIGHT
RAIN...ESPECIALLY LATE TONIGHT THROUGH MID MORNING THURSDAY.
EXPECT AREAS OF RAIN TO DRIFT NORTHWARD OVERNIGHT AND THURSDAY
MORNING...WITH SCATTERED TO NUMEROUS SHOWERS DEVELOPING THURSDAY
AFTERNOON.
LIGHT NORTHEAST SFC WINDS THIS EVENING WILL GRADUALLY BECOME MORE
EASTERLY OVERNIGHT AS SFC HIGH PRESSURE MOVES EASTWARD ACROSS THE
OH VALLEY...ALLOWING WARM FRONT TO MOVE NORTHWARD. BY THURSDAY
AFTERNOON...THE WARM FRONT WILL MOVE NORTH OF MIDDLE TN AND WINDS
WILL BECOME MORE SOUTHEASTERLY/GUSTY IN RESPONSE TO FALLING
PRESSURES ACROSS THE MIDWEST U.S.
PREV DISCUSSION... /ISSUED 517 PM CST WED JAN 9 2013/
UPDATE...ALREADY GETTING SEVERAL REPORTS OF FOG FROM AROUND THE
AREA VIA TWITTER AND NWSCHAT. GIVEN THAT THE AIR IS ALREADY
MOIST, AND WON`T GET ANY LESS MOIST, BELIEVE FOG MAY BECOME MORE
OF A PROBLEM DEEPER INTO THE EVENING. WINDS WILL PICK UP AFTER
MIDNIGHT, SO THE FOG SHOULD BECOME LESS PERVASIVE THEN.
PREV DISCUSSION... /ISSUED 322 PM CST WED JAN 9 2013/
DISCUSSION...
BUSY FORECAST OVER THE NEXT WEEK WITH RAIN CHANCES NEARLY EVERY
PERIOD...NEAR RECORD HIGH TEMPERATURES...HEAVY RAINFALL AND
POSSIBLE FLOOD IMPACTS...AND POTENTIAL FOR EVEN SOME WINTER
WEATHER EARLY NEXT WEEK.
RADAR THIS AFTERNOON SHOWS RAIN HAS MOSTLY DIMINISHED ACROSS THE
CWA EXCEPT OVER THE FAR SOUTH AND SOUTHEAST. HOWEVER...RAIN
CONTINUES TO DEVELOP ACROSS NORTHERN MS/AL TO THE NORTH OF A WARM
FRONT LOCATED ACROSS CENTRAL MS/AL. AS THE FRONT LIFTS NORTHWARD
TONIGHT...SHOWERS AND EVEN A FEW THUNDERSTORMS WILL CONTINUE TO
DEVELOP ALONG AND NORTH OF THE BOUNDARY AND SPREAD ACROSS THE MID
STATE. BEST RAIN CHANCES WILL BE IN WESTERN HALF OF FORECAST AREA
WHERE VERTICAL MOTION WILL BE STRONGER...AND CATEGORICAL POPS
APPEAR WARRANTED AFTER MIDNIGHT. MUCH WARMER TEMPERATURES ARE ALSO
ANTICIPATED TONIGHT DUE TO THE CONTINUED WAA WITH LOWS IN THE
UPPER 40S AND 50S.
SHOWERS AND STORMS WILL TEND TO DIMINISH FROM SOUTH TO NORTH DURING
THE DAY ON THURSDAY AS ACTIVITY FOCUSES MORE TO THE WEST CLOSER TO
UPPER LEVEL LOW TRACK. HOWEVER...CONVECTION WILL SPREAD BACK EAST
INTO THE MID STATE THURSDAY NIGHT AS WEAKENING UPPER LOW PASSES
OFF TO OUR NORTH...WITH HIGHEST POPS IN OUR NORTHWEST ZONES.
STRONG DEEP LAYER SHEAR AND VERY WEAK INSTABILITY COULD PROMPT A
FEW STRONG STORMS OVER OUR WEST AND NORTHWEST THURSDAY NIGHT...BUT
NO SEVERE WEATHER IS EXPECTED AT THIS TIME. PRECIP WILL DIMINISH
FROM WEST TO EAST ON FRIDAY...WITH PARTLY CLOUDY SKIES POSSIBLE BY
AFTERNOON. THIS WILL ALLOW FOR POTENTIAL RECORD HIGH TEMPERATURES
WITH HIGHS IN THE UPPER 60S AND LOW 70S. RECORDS FOR FRIDAY ARE 72
DEGREES AT NASHVILLE IN 1890...AND 64 DEGREES AT CROSSVILLE IN
1960...AND CURRENT FORECAST TIES OR BEATS THE RECORDS AT BOTH
LOCATIONS.
A HIGHER IMPACT EVENT IS FORECAST TO BEGIN ON SATURDAY AND
CONTINUE THROUGH WEDNESDAY OF NEXT WEEK AS A LARGE AND POWERFUL
UPPER TROUGH DIGS ACROSS THE WESTERN CONUS...WITH SEVERAL
SHORTWAVES IN THE SOUTHWESTERLY FLOW ALOFT OVER THE EASTERN PART
OF THE COUNTRY BRINGING US NUMEROUS ROUNDS OF RAIN AND SOME
THUNDERSTORMS. INITIAL SHORTWAVE TROUGH WILL CROSS THE REGION LATE
SATURDAY INTO SATURDAY NIGHT...FORCING A COLD FRONT SOUTHEAST INTO
THE MID STATE ON SUNDAY. ALL MODEL GUIDANCE INDICATES AN AXIS OF
HEAVY RAINFALL WILL SET UP ALONG THE BOUNDARY AS STRONG MOISTURE
TRANSPORT FROM THE GULF OF MEXICO WITH PWATS AS HIGH AS 1.75
INCHES INTERACTS WITH THE FRONT. SUCH A STRONG POSITIVE MOISTURE
ANOMALY...NEARLY ONE QUARTER INCH OVER THE CLIMATOLOGICAL MAXIMUM
PWAT FOR JANUARY...COMBINED WITH FRONTAL BOUNDARY FOCUS RAISES
EYEBROWS ON HEAVY RAINFALL POSSIBILITY AND POTENTIAL FOR FLOODING.
HOWEVER...REMAINS DIFFICULT TO DISCERN AT THIS EXTENDED FORECAST
RANGE EXACTLY WHERE FRONT WILL END UP...AND WHERE ANY POSSIBLE
FLOOD IMPACTS WOULD OCCUR. FOR NOW WILL JUST SHOW LIKELY TO
CATEGORICAL POPS IN THE SATURDAY THROUGH MONDAY TIME
FRAME...CHANCE TO LIKELY POPS TUESDAY INTO WEDNESDAY BEFORE PRECIP
ENDS...AND REISSUE ESF TO HIGHLIGHT HEAVY RAINFALL AND FLOOD
POTENTIAL. CURRENTLY APPEARS THAT SOME PORTION OF THE MID STATE
COULD RECEIVE SEVERAL INCHES OF RAIN DURING THIS TIME PERIOD.
IN ADDITION...12Z GFS/ECMWF RUNS SUGGEST FRONT WILL MOVE FAR
ENOUGH SOUTHEAST TO ALLOW FOR SIGNIFICANT CAA OVER FAR NORTHWEST
ZONES...WITH TEMPERATURES COLD ENOUGH FOR POSSIBLE WINTER
PRECIPITATION. FORECAST SOUNDINGS SUGGEST MARGINAL CONDITIONS FOR
FREEZING RAIN OR SLEET BOTH MONDAY AND TUESDAY MORNINGS...BUT THIS
IS HIGHLY UNCERTAIN AT THIS RANGE AND VERY DEPENDENT ON FRONTAL
POSITION AND TEMPERATURES. FOR NOW WILL LEAVE FORECAST AS ALL
RAIN DUE TO THE UNCERTAINTY AND KEPT TEMPERATURES NEAR MEX MOS
VALUES.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
49
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1006 PM CST WED JAN 9 2013
.UPDATE...CURRENT FORECAST FOR MIDDLE TENNESSEE IS HOLDING UP WELL
FOR THE MOST PART. RAIN CONTINUES TO PROPAGATE NORTHWARD WHILE
WEAKENING. LATEST HRRR SHOWS MAINLY LIGHT PRECIPITATION CONTINUING
OVERNIGHT. GIVEN THE CURRENT RADAR TREND, WILL UPDATE THE FORECAST
SHORTLY TO REMOVE THE SLIGHT CHANCE OF THUNDER WE HAVE RUNNING IN
THE OVERNIGHT PERIOD. BUT NO OTHER CHANGES ARE PLANNED AT THIS
TIME.
&&
.PREV DISCUSSION... /ISSUED 614 PM CST WED JAN 9 2013/
UPDATE...FOR 00Z AVIATION FORECAST
AVIATION...
THIS 24 HOUR PERIOD WILL BE DOMINATED BY PLENTY OF MOISTURE THANKS
TO STRONG H5 LOW REMAINING WELL TO OUR WEST. THE LOW HAS BEEN OVER
THE TX BIG BEND LATELY BUT SHOULD START MOVING NORTHEAST TOWARD
OKLAHOMA OVERNIGHT AND THURSDAY.
EXTENSIVE CLOUDS WILL CONTINUE ACROSS THE REGION THROUGH AT LEAST
00Z FRIDAY...WITH WIDESPREAD MVRF/IFR CONDITIONS AND POCKETS OF
LIFR. VSBYS WILL FREQUENTLY BE 4SM OR LESS IN FOG AND LIGHT
RAIN...ESPECIALLY LATE TONIGHT THROUGH MID MORNING THURSDAY.
EXPECT AREAS OF RAIN TO DRIFT NORTHWARD OVERNIGHT AND THURSDAY
MORNING...WITH SCATTERED TO NUMEROUS SHOWERS DEVELOPING THURSDAY
AFTERNOON.
LIGHT NORTHEAST SFC WINDS THIS EVENING WILL GRADUALLY BECOME MORE
EASTERLY OVERNIGHT AS SFC HIGH PRESSURE MOVES EASTWARD ACROSS THE
OH VALLEY...ALLOWING WARM FRONT TO MOVE NORTHWARD. BY THURSDAY
AFTERNOON...THE WARM FRONT WILL MOVE NORTH OF MIDDLE TN AND WINDS
WILL BECOME MORE SOUTHEASTERLY/GUSTY IN RESPONSE TO FALLING
PRESSURES ACROSS THE MIDWEST U.S.
PREV DISCUSSION... /ISSUED 517 PM CST WED JAN 9 2013/
UPDATE...ALREADY GETTING SEVERAL REPORTS OF FOG FROM AROUND THE
AREA VIA TWITTER AND NWSCHAT. GIVEN THAT THE AIR IS ALREADY
MOIST, AND WON`T GET ANY LESS MOIST, BELIEVE FOG MAY BECOME MORE
OF A PROBLEM DEEPER INTO THE EVENING. WINDS WILL PICK UP AFTER
MIDNIGHT, SO THE FOG SHOULD BECOME LESS PERVASIVE THEN.
PREV DISCUSSION... /ISSUED 322 PM CST WED JAN 9 2013/
DISCUSSION...
BUSY FORECAST OVER THE NEXT WEEK WITH RAIN CHANCES NEARLY EVERY
PERIOD...NEAR RECORD HIGH TEMPERATURES...HEAVY RAINFALL AND
POSSIBLE FLOOD IMPACTS...AND POTENTIAL FOR EVEN SOME WINTER
WEATHER EARLY NEXT WEEK.
RADAR THIS AFTERNOON SHOWS RAIN HAS MOSTLY DIMINISHED ACROSS THE
CWA EXCEPT OVER THE FAR SOUTH AND SOUTHEAST. HOWEVER...RAIN
CONTINUES TO DEVELOP ACROSS NORTHERN MS/AL TO THE NORTH OF A WARM
FRONT LOCATED ACROSS CENTRAL MS/AL. AS THE FRONT LIFTS NORTHWARD
TONIGHT...SHOWERS AND EVEN A FEW THUNDERSTORMS WILL CONTINUE TO
DEVELOP ALONG AND NORTH OF THE BOUNDARY AND SPREAD ACROSS THE MID
STATE. BEST RAIN CHANCES WILL BE IN WESTERN HALF OF FORECAST AREA
WHERE VERTICAL MOTION WILL BE STRONGER...AND CATEGORICAL POPS
APPEAR WARRANTED AFTER MIDNIGHT. MUCH WARMER TEMPERATURES ARE ALSO
ANTICIPATED TONIGHT DUE TO THE CONTINUED WAA WITH LOWS IN THE
UPPER 40S AND 50S.
SHOWERS AND STORMS WILL TEND TO DIMINISH FROM SOUTH TO NORTH DURING
THE DAY ON THURSDAY AS ACTIVITY FOCUSES MORE TO THE WEST CLOSER TO
UPPER LEVEL LOW TRACK. HOWEVER...CONVECTION WILL SPREAD BACK EAST
INTO THE MID STATE THURSDAY NIGHT AS WEAKENING UPPER LOW PASSES
OFF TO OUR NORTH...WITH HIGHEST POPS IN OUR NORTHWEST ZONES.
STRONG DEEP LAYER SHEAR AND VERY WEAK INSTABILITY COULD PROMPT A
FEW STRONG STORMS OVER OUR WEST AND NORTHWEST THURSDAY NIGHT...BUT
NO SEVERE WEATHER IS EXPECTED AT THIS TIME. PRECIP WILL DIMINISH
FROM WEST TO EAST ON FRIDAY...WITH PARTLY CLOUDY SKIES POSSIBLE BY
AFTERNOON. THIS WILL ALLOW FOR POTENTIAL RECORD HIGH TEMPERATURES
WITH HIGHS IN THE UPPER 60S AND LOW 70S. RECORDS FOR FRIDAY ARE 72
DEGREES AT NASHVILLE IN 1890...AND 64 DEGREES AT CROSSVILLE IN
1960...AND CURRENT FORECAST TIES OR BEATS THE RECORDS AT BOTH
LOCATIONS.
A HIGHER IMPACT EVENT IS FORECAST TO BEGIN ON SATURDAY AND
CONTINUE THROUGH WEDNESDAY OF NEXT WEEK AS A LARGE AND POWERFUL
UPPER TROUGH DIGS ACROSS THE WESTERN CONUS...WITH SEVERAL
SHORTWAVES IN THE SOUTHWESTERLY FLOW ALOFT OVER THE EASTERN PART
OF THE COUNTRY BRINGING US NUMEROUS ROUNDS OF RAIN AND SOME
THUNDERSTORMS. INITIAL SHORTWAVE TROUGH WILL CROSS THE REGION LATE
SATURDAY INTO SATURDAY NIGHT...FORCING A COLD FRONT SOUTHEAST INTO
THE MID STATE ON SUNDAY. ALL MODEL GUIDANCE INDICATES AN AXIS OF
HEAVY RAINFALL WILL SET UP ALONG THE BOUNDARY AS STRONG MOISTURE
TRANSPORT FROM THE GULF OF MEXICO WITH PWATS AS HIGH AS 1.75
INCHES INTERACTS WITH THE FRONT. SUCH A STRONG POSITIVE MOISTURE
ANOMALY...NEARLY ONE QUARTER INCH OVER THE CLIMATOLOGICAL MAXIMUM
PWAT FOR JANUARY...COMBINED WITH FRONTAL BOUNDARY FOCUS RAISES
EYEBROWS ON HEAVY RAINFALL POSSIBILITY AND POTENTIAL FOR FLOODING.
HOWEVER...REMAINS DIFFICULT TO DISCERN AT THIS EXTENDED FORECAST
RANGE EXACTLY WHERE FRONT WILL END UP...AND WHERE ANY POSSIBLE
FLOOD IMPACTS WOULD OCCUR. FOR NOW WILL JUST SHOW LIKELY TO
CATEGORICAL POPS IN THE SATURDAY THROUGH MONDAY TIME
FRAME...CHANCE TO LIKELY POPS TUESDAY INTO WEDNESDAY BEFORE PRECIP
ENDS...AND REISSUE ESF TO HIGHLIGHT HEAVY RAINFALL AND FLOOD
POTENTIAL. CURRENTLY APPEARS THAT SOME PORTION OF THE MID STATE
COULD RECEIVE SEVERAL INCHES OF RAIN DURING THIS TIME PERIOD.
IN ADDITION...12Z GFS/ECMWF RUNS SUGGEST FRONT WILL MOVE FAR
ENOUGH SOUTHEAST TO ALLOW FOR SIGNIFICANT CAA OVER FAR NORTHWEST
ZONES...WITH TEMPERATURES COLD ENOUGH FOR POSSIBLE WINTER
PRECIPITATION. FORECAST SOUNDINGS SUGGEST MARGINAL CONDITIONS FOR
FREEZING RAIN OR SLEET BOTH MONDAY AND TUESDAY MORNINGS...BUT THIS
IS HIGHLY UNCERTAIN AT THIS RANGE AND VERY DEPENDENT ON FRONTAL
POSITION AND TEMPERATURES. FOR NOW WILL LEAVE FORECAST AS ALL
RAIN DUE TO THE UNCERTAINTY AND KEPT TEMPERATURES NEAR MEX MOS
VALUES.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
ROSE
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1035 AM CST THU JAN 10 2013
.UPDATE...
HAVE PUSHED BACK PRECIP CHANCES UNTIL 21Z IN THE FAR
SOUTHWEST...AND ABOUT 23Z IN MILWAUKEE AND MADISON. THE
NAM12...GEM...SREF...CRAS SHOW LITTLE TO NO PRECIPITATION BEFORE
21Z. THE HRRR EVEN KEEPS THE FAR SOUTHWEST DRY UNTIL 22Z AND THE
IN HOUSE WRF THROUGH 00Z. AN ENSEMBLE OF HI RES MODELS...SPC
SSEO...EVEN SHOWS PRECIP STAYING SOUTH OF A MADISON TO LAKE
GENEVA LINE THROUGH 00Z AND THEN EVERYONE SEEING PRECIPITATION BY
03Z...WITH THE HEAVIEST PRECIP BETWEEN 03Z AND 09Z. WILL KEEP AN
EYE ON MODELS AND RADAR TRENDS TO SEE IF THE PRECIP ARRIVAL NEEDS
TO BE DELAYED EVEN MORE.
A LARGE TEMPERATURE SPREAD EXISTS ACROSS THE AREA...WITH 37 IN
KENOSHA AND 23 IN LONE ROCK AND 24 IN SHEBOYGAN. NONE OF THE
MODELS ARE DOING A GREAT JOB OF CAPTURING THE COOLER TEMPERATURES
TO THE NORTH AND NORTHWEST. MAY HAVE TO LOWER HIGH TEMPS IN THE
NORTHWEST. HOWEVER...TEMPS IN THE FAR SOUTHEAST MAY NEED TO BE
BUMPED UP ANOTHER DEGREE OR TWO. WILL CONTINUE TO MONITOR TRENDS.
&&
.PREV DISCUSSION... /ISSUED 338 AM CST THU JAN 10 2013/
TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM
KICKER TROUGH MOVING ASHORE ON THE WEST COAST WILL TAKE CLOSED LOW
CURRENTLY OVER SW TEXAS ON WATER VAPOR LOOPS...OPEN IT AND LIFT IT
NORTHEAST ACROSS THE SOUTHERN/CENTRAL PLAINS AS A NEGATIVELY TILTED
WAVE AS UPPER JET BUCKLES NORTHWARD OVER THE CENTRAL U.S./SRN CANADA
IN RESPONSE TO WESTERN TROUGH.
FIRST SURGE OF MID-LEVEL WAA/MOISTURE...ENHANCED BY 500-300MB DIFF
VORT ADVECTION WITH SHEARED VORTICITY IN AXIS OF SHORT WAVE RIDGE TO
THE NORTH OF SOUTHERN PLAINS TROUGH...LIFTS ACROSS SRN WI THIS
AFTERNOON. CONDENSATION PRESSURE DEFICITS OF 100 MB OR MORE ON
FORECAST 280K AND 285K SURFACES UNTIL MID-LATE AFTERNOON SUPPORT
LACK OF MOISTURE BELOW 10K FT ON CROSS SECTIONS AND FORECAST
SOUNDINGS THAT NEEDS TO SATURATE BEFORE ANY PRECIP REACHES THE
GROUND.
SATURATION WILL BE RAPID AROUND/AFTER 21Z. WILL TREND ONSET OF PCPN
FROM SW TO NE WITH LOWER CONDENSATION PRESSURE DEFICITS. PW/S
RAPIDLY JUMPING FROM ABOUT 0.25 INCH LATE MORNING TO A MAX AROUND
1.25 INCHES OVERNIGHT...OR 350-400 PCT OF NORMAL...AS GULF MOISTURE
FLOWS NWD AHEAD OF SURFACE WAVE. MAX FORCING/OMEGA BRINGS HEAVIEST
RAIN TO THE SOUTH AROUND 06Z...AND 09Z TO THE NORTHEAST CWA WITH
SOME TALL...SKINNY ELEVATED CAPE PROFILES ON FORECAST SOUNDINGS. NOT
ENOUGH INSTABILITY TO MENTION THUNDER...BUT A RUMBLE OR TWO NOT OUT
OF THE QUESTION.
SOME MODEL DIFFERENCES WITH SPEED OF 500 MB TROUGH AND TRACK OF VORT
MAX IN BASE OF TROUGH AND THE ASSOCIATED SURFACE WAVE LEADS TO
DIFFERING PLACEMENT OF AXIS OF HEAVIEST PRECIPITATION. WILL USE A
BLEND OF MODEL QPF AMOUNTS WHICH WILL BRING AROUND 1/2 INCH TO
WESTERN PORTIONS OF THE CWA UP TO 3/4 INCH IN THE SOUTHEAST...WITH
LOCALLY HIGHER AMOUNTS CLOSE TO AN INCH WITH THE BRIEF CONVECTIVE
POTENTIAL.
FRIDAY AND SATURDAY...FORECAST CONFIDENCE...MEDIUM
SURFACE LOW WILL BE OVERHEAD FRIDAY MORNING...WITH RAIN CONTINUING
TO WIND DOWN AS THE LOW LIFTS NORTHEAST. KEPT CHANCE FOR RAIN IN THE
MORNING...WITH THINGS TURNING DRY BY EARLY AFTERNOON. MAY BE SOME
DRIZZLE ACROSS THE WESTERN FORECAST AREA LATE AFTERNOON AND EVENING.
TEMPS WILL BE QUITE MILD...WITH EXPECTED HIGHS JUST A FEW DEGREES
BELOW RECORD VALUES.
KEPT MENTION OF FOG FRIDAY AND FRIDAY NIGHT...AS DEWPOINTS WILL BE
IN THE LOW TO MID 40S. TOUGH TO KNOW EXACTLY HOW MUCH FOG THERE WILL
BE IN THE EAST...ALL DEPENDING ON HOW MUCH SNOW IS LEFT BY THEN.
WOULD NOT BE SURPRISED IF THE FOG IS DENSE FOR A WHILE...ESPECIALLY
AREAS FARTHER WEST WHERE THE SNOW IS DEEPER AND WILL HOLD ON LONGER.
A STRONG COLD FRONT WILL MOVE THROUGH THE FORECAST AREA SATURDAY
MORNING. MODELS HAVE BEEN GOING BACK AND FORTH WITH THE TIMING OF
THIS FRONT...SO KIND OF A PAIN FIGURING OUT FRIDAY NIGHT LOWS AND
SATURDAY HIGHS...AS A CHANGE IN FRONT TIMING WILL IMPACT THESE QUITE
A BIT. EITHER WAY THOUGH...WILL EVENTUALLY SEE TEMPS HEAD DOWNWARD
SOMETIME SATURDAY MORNING...LIKELY CONTINUING TO FALL THROUGH THE
AFTERNOON. BREEZY WESTERLY WINDS BEHIND THE FRONT WILL MAKE IT FEEL
EVEN CHILLIER.
KEPT CHANCE FOR SNOW SOUTHEAST SATURDAY NIGHT...AS IT STILL LOOKS
LIKE LIGHT ACCUMULATIONS MAY BRUSH THE AREA. BEST CHANCE LOOKS
MAINLY SOUTHEAST OF A MILWAUKEE TO JANESVILLE LINE. UNLESS THIS
SYSTEM COMES FARTHER NORTH THAN CURRENTLY EXPECTED...WOULD ONLY SEE
MAYBE UP TO AN INCH TOWARD THE ILLINOIS BORDER.
SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE...MEDIUM
ANY LINGERING LIGHT SNOW IS EXPECTED TO WIND DOWN QUICKLY SUNDAY
MORNING. LOOKS DRY THEN THROUGH THE MIDDLE OF NEXT WEEK. TEMPS WILL
BE COLDER EARLY NEXT WEEK...THOUGH NEAR TO JUST A FEW DEGREES BELOW
NORMAL FOR THIS TIME OF THE YEAR. COULD SEE HIGHS WARM TO A FEW
DEGREES ABOVE NORMAL BY MID WEEK.
AVIATION/12Z TAFS/...
WILL KEEP VFR CONDITIONS THROUGH MOST OF THE DAY WITH CLOUDS
THICKENING/LOWERING...THEN CONDITIONS WILL DETERIORATE QUICKLY WITH
SURGE OF DEEPER MOISTURE AND ONSET OF PRECIPITATION BETWEEN 21Z AND
00Z. MODEL SOUNDINGS AND MOS GUIDANCE IN GOOD AGREEMENT THAT IFR
CIGS AND VSBYS WILL SETTLE IN AT ALL TAF SITES BY 03Z FRIDAY AND
STAY DOWN THROUGH THE REMAINDER OF THE FORECAST PERIOD...EVEN UNTIL
18Z FRI AT KMKE. TEMPERATURES WILL BE WARM ENOUGH FOR ALL THE
PRECIPITATION TO BE LIQUID.
MARINE...
SOUTHEAST WINDS STEADILY INCREASE THROUGH THE DAY AS PRESSURE
GRADIENT TIGHTENS BETWEEN DEPARTING HIGH PRESSURE TO THE EAST AND
APPROACHING SURFACE LOW FROM THE SOUTH. WINDS SHIFT SOUTHWEST
DECREASE FOR A TIME FRIDAY AS WEAKENING SURFACE LOW MOVES THROUGH
REGION...THEN SOUTHERLY WINDS INCREASE LATE FRIDAY NIGHT AS
DEEPENING SURFACE LOW MOVES TOWARD REGION FROM THE NORTHERN PLAINS.
WILL ISSUE A SMALL CRAFT ADVISORY FROM LATE THIS AFTERNOON UNTIL 00Z
SATURDAY...THOUGH IT MAY HAVE TO BE EXTENDED IF WAVES TO NOT SUBSIDE
AS EXPECTED BEFORE WINDS INCREASE LATE FRIDAY NIGHT.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM CST FRIDAY
FOR LMZ643>646.
&&
$$
UPDATE...MEB/SM
TODAY/TONIGHT AND AVIATION/MARINE...REM
FRIDAY THROUGH WEDNESDAY...DDV
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
100 AM EST SAT JAN 12 2013
.AVIATION... /06 UTC TAFS/
PRIME FOCUS ON CURRENT/NEXT HAZARDS...LLWS/RAIN RESPECTIVELY. SLIGHT
ADJUSTMENTS TO SLIGHTLY MORE VEERED LLJ PER PRESENT UPSTREAM
VWP/PROFILER DATA AND RAP ANALYSIS. FOCUS FOR RENEWED LIFT IN
WARM/ABNORMALLY MOIST ENVIRONMENT COMMENCES LATE TONIGHT AND HAVE
INTRODUCED DOWNWARD TREND. SUSPECT HIR PROB FOR MORE WIDESPREAD IFR
MET CONDS TO BE REALIZED WITH TIME/BY 12 UTC SUN ACRS NRN IN...AND
TO BE ASSESSED IN LATER FCSTS.
&&
.UPDATE...
LINGERING STRATOCU HAS LIFTED NORTHWARD ACROSS SOUTHERN LOWER
MICHIGAN THIS EVENING WITH MAINLY HIGH LEVEL CLOUDINESS PERSISTING
ACROSS THE AREA. THE COMBINATION OF CONTINUED HIGH LEVEL CLOUDS
OVERNIGHT AND MODERATE GRADIENT PERSISTING SHOULD ALLOW FOR
MINIMAL TEMP DROPS FOR THE REMAINDER OF THE NIGHT. DESPITE
GRADIENT...SURFACE OBSERVATIONS ACROSS THE REGION INDICATING SOME
FAIRLY GOOD DECOUPLING EARLIER THIS EVENING WHICH HAVE ALLOWED
TEMPS TO DROP INTO THE MID AND UPPER 40S ACROSS NORTHERN PORTIONS
OF THE AREA. A FEW MORE DEGREES OF TEMPERATURE DROP ARE POSSIBLE
THIS EVENING...BEFORE A MORE STEADY TEMPERATURE TREND BECOMES
ESTABLISHED OVERNIGHT AS LOW LEVEL JET STRENGTHENS PLACING LOCAL
AREA IN MORE ROBUST WARM SECTOR ONCE AGAIN. SOME MINOR TWEAKS MADE
TO HOURLY TEMPERATURE CURVE TO ACCOUNT FOR EARLIER EVENING
DECOUPLING...BUT PREVIOUS FORECAST APPEARS TO BE IN GOOD SHAPE.
&&
.PREV DISCUSSION... /ISSUED 335 PM EST FRI JAN 11 2013/
SHORT TERM.../TONIGHT THROUGH SATURDAY NIGHT/
BALMY MID JANUARY WX IS EXPECTED TO CONTINUE INTO TONIGHT AND
SATURDAY...WITH ANOTHER ROUND OF RAIN (MIXING WITH SLEET/FREEZING
RAIN WESTERN AREAS) SATURDAY NIGHT...
DEEP SOUTHWESTERLY FLOW IN ADVANCE OF A DEEP WESTERN CONUS FULL
LATITUDE UPPER TROUGH WILL KEEP TEMPS UNUSUALLY MILD TONIGHT INTO
TOMORROW AS WARM SECTOR HAS BUILT IN BEHIND LAST NIGHTS LEAD WAVE
AND WARM FRONT. LOWS TONIGHT WILL BE AN IMPRESSIVE ~30F ABOVE
NORMAL WITH HIGHS ~25F ABOVE NORMAL TOMORROW.
ATTENTION THEN TURNS TO QPF/PTYPE OF PCPN PROGGED TO IMPACT THE
ENTIRE AREA SATURDAY NIGHT. LEAD WAVE OF LOW PRESSURE TRACKING
NORTHEAST THROUGH THE UPPER MIDWEST AND INTO ONTARIO TONIGHT INTO
SATURDAY WILL FORCE A SFC FRONTAL BOUNDARY SOUTHEAST INTO
SOUTHEASTERN PORTIONS OF OUR FA BY SATURDAY
AFTERNOON/EVENING...STALLING OUT HERE UNDER SOUTHWEST FLOW ALOFT.
A FRONTAL WAVE WILL DEVELOP ALONG THIS STALLED FRONT AS SHEARED
SHORTWAVE ENERGY NOW JUST OFF THE SOUTHERN CALIFORNIA COAST ROUNDS
THE BASE OF THE DEEP WESTERN CONUS TROUGH AND PROPAGATES NORTHEAST
INTO THE MID MS VALLEY AND GREAT LAKES. MODERATE TO HEAVY RAIN
SHOULD BLOSSOM ALONG THE DEEPENING FRONTAL CIRCULATION WITH A
STRONG AGEOSTROPHIC RESPONSE ANTICIPATED UNDER THE RIGHT ENTRANCE
REGION OF A 160 KT UPPER JET. THIS COMBINED WITH AN OPEN GULF OF
MEXICO AND DECREASED STABILITY (MODELS DEPICTING -EPV AND THETA-E
FOLDING ON XSECTIONS JUST ABOVE THE FRONTAL INVERSION) HINTS AT A
CONVECTIVE ELEMENT WITH A NARROW AXIS OF 1-2 INCH RAINFALL TOTALS
POSSIBLE INTO NE INDIANA AND NW OHIO. THIS COULD LEAD TO SOME
MINOR HYDRO RELATED PROBLEMS...CHECK ESFIWX (HYDROLOGIC OUTLOOK)
FOR DETAILS.
PTYPE BECOMES A CONCERN ACROSS NW INDIANA AND SW LOWER MICHIGAN
SATURDAY NIGHT...MAINLY AFTER MIDNIGHT...AS COLD AIR UNDERCUTS THE
LINGERING MELTING LAYER AND DYNAMIC COOLING COMMENCES. LATEST SREF
PROBABILITIES, ALONG WITH GFS/ECMWF ITERATIONS, SUGGEST THAT BETTER
CHANCES FOR MEASURABLE SNOW/SLEET WILL BE JUST WEST OF OUR AREA. SFC
TEMPS MAY COOL TO NEAR FREEZING AFTER 08/09Z IN OUR NW WHICH COULD
ALLOW FOR A BRIEF PERIOD OF FREEZING RAIN. EXPECT ANY FZRA TO BE
TRANSIENT WITH QUICK CHANGEOVER TO LIGHT SNOW/SLEET/DRIZZLE
LIMITING/INHIBITING ICE ACCRETIONS. OTHERWISE...OPTED TO HOLD
WITH SNOW/SLEET ACCUMS OF A TRACE TO 0.5" IN OUR FAR NORTHWESTERN
ZONES...MAINLY RAIN ELSEWHERE THROUGH DAYBREAK SUNDAY.
LONG TERM.../SATURDAY THROUGH THURSDAY/
MAIN CONCERN FOR LONG TERM PERIOD IS PRECIP TYPE ON SUNDAY AS
STORM SYSTEM DEPARTS. NEXT WEEK WILL FEATURE COLDER AIR AND A FEW
ALBERTA CLIPPER SYSTEMS MOVING BY TO OUR NORTH.
A POTPOURRI OF PRECIPITATION TYPES POSSIBLE ACROSS THE AREA ON
SUNDAY DEPENDING ON WHICH MODEL IS FAVORED. ECMWF THERMAL PROFILE
INDICATES FREEZING RAIN POTENTIAL ON SUNDAY MORNING FROM HIGHWAY 15
WEST WHILE GFS WOULD INDICATE NO FREEZING RAIN POSSIBILITY AND A
TRANSITION FROM RAIN TO MOSTLY SNOW WITH SOME SLEET BY MID DAY. WITH
TRANSITION ZONE DIRECTLY OVER THE FORECAST AREA...AND MODEL
UNCERTAINTY...HAVE KEPT MOST ALL PRECIP TYPES IN THE FORECAST AND
WILL ATTEMPT TO NARROW THE POSSIBILITIES IN FUTURE FORECAST
ISSUANCES.
AFTER THIS SYSTEM MOVES AWAY...A COLDER AIRMASS WILL MOVE IN. IF WE
CLEAR OUT ON MONDAY NIGHT...TEMPERATURES COULD GET QUITE COLD WITH A
HIGH PRESSURE CENTER OVER EASTERN ILLINOIS KEEPING WINDS LIGHT TO
CALM. A FEW CLIPPER TYPE SYSTEMS WILL MOVE BY TO OUR NORTH NEXT
WEEK. CONTINUED NORTHERLY FLOW BEHIND THESE SYSTEMS WILL ALLOW
ARCTIC CANADIAN AIR TO INFILTRATE MOST OF THE MIDWEST/UPPER GREAT
LAKES BY THE END OF THE WEEK. LONG TERM PATTERN LOOKS TO REMAIN
COOLER THAN NORMAL AS EASTERN CANADA TROUGH KEEPS OUR AREA IN
NORTHERLY FLOW.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST SATURDAY FOR LMZ043-046.
&&
$$
SHORT TERM...STEINWEDEL
LONG TERM...BENTLEY
AVIATION...MURPHY
UPDATE...MARSILI
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1132 PM CST FRI JAN 11 2013
.AVIATION...
VFR CONDITIONS WILL PREVAIL MOST TO ALL OF THE NEXT 24 HOURS AT ALL
TERMINALS. KCID AND KDBQ TERMINALS...A 1 TO 3 HOUR PERIOD OF SCT-
BKN LOW CLOUDS AT 1-2K AGL MAY FOLLOW COLD FRONTAL PASSAGE BETWEEN
12-15Z THIS MORNING. AFTER 21Z...BKN-OVC LOW/MID CLOUDS WITH
POSSIBLY LIGHT SNOW MAY AFFECT KMLI AND KBRL TERMINALS WITH MVFR
CONDITIONS POSSIBLE IN ANY SNOW THROUGH 13/06Z.
NICHOLS
&&
.PREV DISCUSSION... /ISSUED 302 PM CST FRI JAN 11 2013/
SYNOPSIS...
12Z UA ANALYSIS HAS A STRONG SYSTEM OVER THE ROCKIES WITH STRONG
SOUTHWEST FLOW FROM NORTHERN MEXICO INTO THE GREAT LAKES.
SATELLITE TRENDS THROUGH MID AFTERNOON INDICATE THE LOW CLOUDS ARE
BREAKING UP AS DEEPER MIXING OCCURS BUT MID AND HIGH LEVEL CLOUDS
ARE STREAMING IN OVER THE REMAINING LOW CLOUDS.
18Z SFC ANALYSIS HAS A LOW NORTH OF KATY WITH ANOTHER NORTHEAST OF
KLIC. A STRONG COLD FRONT CONNECTED BOTH LOWS AND THERE WERE
NUMEROUS TROFS FROM THE GREAT LAKES BACK INTO THE SOUTHERN PLAINS.
DEW POINTS WERE IN THE TEENS AND 20S ACROSS THE NORTHERN PLAINS
WITH 30S AND 40S ACROSS MUCH OF THE GREAT LAKES AND MIDWEST. DEW
POINTS IN THE 50S AND 60S RAN FROM THE OHIO VALLEY INTO THE DEEP
SOUTH.
SHORT TERM...LATE THIS AFTERNOON THROUGH SATURDAY
WE ARE DEALING WITH ADVECTION FOG. IN ADVECTION FOG YOU CAN HAVE
EXTREMELY DENSE FOG EVEN THOUGH WINDS ARE 10 TO 20 MPH. ALBEIT FAR
FROM PERFECT...THE RAP MODEL TRENDS STRONGLY POINT TO DENSE FOG
CONTINUING INTO THE EVENING ACROSS THE NORTHERN CWFA.
AS FOR HEADLINES...THE DENSE FOG ADVISORY WILL BE EXTENDED UNTIL
MIDNIGHT FROM DUBUQUE ON WEST IN THE HWY 20 CORRIDOR. PER
OBSERVATIONS AND WHAT WEB CAMS ARE AVAILABLE...THE NORTHERN PARTS
OF LINN/JONES/JACKSON COUNTIES IN IOWA AND STEPHENSON COUNTY IN
ILLINOIS STILL HAVE DENSE FOG OVER THEM. THUS THESE COUNTIES AND
JO DAVIESS COUNTY WILL HAVE THE DENSE FOG ADVISORY EXTENDED
THROUGH 6 PM.
THE POSSIBILITY DOES EXIST THAT THE HEADLINES MAY BE DROPPED
EARLY. THAT WILL DEPEND UPON STRONGER WINDS PROMOTING MIXING OF
THE BOUNDARY LAYER TO CAUSE THE FOG TO LIFT.
AFTER MIDNIGHT...A STRONG COLD FRONT WILL SWEEP THROUGH THE CWFA.
THIS FRONT WILL SCOUR OUT WHAT REMAINING FOG IS ACROSS THE AREA.
VERY BRISK CONDITIONS WILL BE SEEN ACROSS THE AREA ON SATURDAY
BEHIND THE FRONT.
THE STRENGTH OF THE CAA ON SATURDAY WOULD NORMALLY RESULT IN
UNSTABLE CONDITIONS WITH CONVECTIVE SHOWERS DEVELOPING. HOWEVER...
LOW LEVEL LAPSE RATES REMAIN QUITE STABLE DURING THE DAY AND FCST
SOUNDINGS SHOW A VERY PRONOUNCED INVERSION ACROSS THE AREA. THUS
SATURDAY WILL REMAIN DRY.
LOW TEMPERATURES TONIGHT WILL OCCUR AROUND 8 AM SATURDAY. THE HIGH
TEMPERATURES FOR THE DAYLIGHT HOURS ON SATURDAY WILL OCCUR BETWEEN
8 AND 10 AM FOLLOWED BY SLOWLY FALLING TEMPERATURES. TEMPERATURES
MAY REBOUND A LITTLE DURING THE AFTERNOON BUT WILL BE BELOW THE
MORNING HIGHS. ..08..
LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
SATURDAY NIGHT AND SUNDAY TO BE THE TRICKY PERIOD. LAST NIGHT THE
ECMWF TOOK A JOG TO THE NORTHWEST WITH A SHORTWAVE AND SURFACE
LOW THAT MOVES FROM EAST TEXAS NORTHEAST UP THE OHIO VALLEY. IT
APPEARS TO BE BRINGING THE WHOLE FEATURE FARTHER NORTHWEST...AS
WELL AS TAKING ADVANTAGE OF SOME DEEPER FRONTOGENESIS THAT SEEMS
TO BE FORMING ON THE NORTH SIDE OF THE FEATURE. THIS
MORNING...MORE OF THE MODELS FOLLOWED THAT TREND...AND ARE NOW
BRINGING A NICE SWATH OF SNOW TO THE FORECAST AREA. AREAS
SOUTHEAST OF A LINE FROM CEDAR RAPIDS TO DUBUQUE ARE NOW LOOKING
AT A NICE 1 TO POSSIBLY 3 INCH SNOWFALL EVENT...ASSUMING WE CAN
GET ENOUGH MOISTURE INTO THE AREA AND THE ECMWF AND GFS
ISENTROPIC AND FRONTOGENESIS LIFT PROGS ARE CORRECT. HAVE RAISED
POPS...BUT IF THIS TREND CONTINUES WITH TONIGHTS MODEL RUNS...WE
COULD RAISE POPS AGAIN.
SUNDAY NIGHT AND MONDAY TO BE COLD...ESPECIALLY IF WE CAN GET
SOME SNOW ON THE GROUND TO ENHANCE THE STRONG SURFACE RIDGE THAT
WILL BE SITTING OVER THE AREA BY EARLY MONDAY MORNING. AT THIS
TIME IT LOOKS LIKE WE MAY SEE SOME SINGLE DIGITS IN THE NORTHWEST
PORTIONS OF THE FORECAST AREA. IF WE DO GET THE NEW
SNOWPACK...NEARLY THE WHOLE CWA COULD HAVE SINGLE DIGIT MINS WITH
NEAR ZERO VALUES POSSIBLE NORTHWEST. HIGHS ON MONDAY TO STILL BE
CHILLY WITH THE RIDGE STILL OVERHEAD...AND CURRENTLY HAVE MID TO
UPPER 20S.
TUESDAY THE MAIN UPPER LEVEL TROUGH TO SLOWLY MOVE
OVERHEAD...INCREASING CLOUD COVER SOMEWHAT AND WITH SOME WEAK
WARM AIR ADVECTION BEGINNING ALOFT SOME MODERATION OF TEMPERATURES
IS POSSIBLE.
WEDNESDAY A STRONG CLIPPER IS LIKELY TO MOVE OUT OF CANADA IN THE
LONGWAVE TROUGH. THIS SYSTEM TO STAY MOSTLY NORTH OF THE
AREA...BUT IT WILL PULL SOME WARMER TEMPERATURES ALOFT OVER THE
AREA...FOR A CONTINUATION OF THE WARMING TREND STARTED ON TUESDAY.
HIGHS WEDNESDAY AFTERNOON SHOULD BE IN THE 30S NEARLY EVERYWHERE.
WITH THE CLIPPER NOW HAVING MOVED OFF TO THE EAST BY WEDNESDAY
NIGHT...A FRESH SHOT OF COLDER AIR WILL MOVE INTO THE CWA FROM
THE NORTH AS THE UPPER LEVEL TROUGH AXIS SHARPENS. IT LOOKS LIKE A
SHORTWAVE MAY DIVE THROUGH THE AREA THURSDAY...BUT SOME MODELS
KEEP IT TOO FAR NORTH TO AFFECT THE AREA...SO HAVE LEFT FORECAST
DRY FOR NOW. FRIDAY LOOKS COLD AND DRY AS WELL.
LE
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
NICHOLS
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1205 AM CST SAT JAN 12 2013
...UPDATED AVIATION DISCUSSION...
.UPDATE...
/834 PM CST Fri Jan 11 2013/
Looking at the latest model runs for tomorrow`s potential
snowfall...some of the higher resolution models are hinting at a
potential band of snow that could develop further west of the main
area of precipitation, from east central KS into north central MO,
possibly including parts of the KC metro. Earlier SREF members,
specifically the ARW members, were the first to pick up on this
possibility and now the 00Z NAM and even RAP are picking up on this
as well. Frontogenesis progs and cross section analysis do indicate
the potential for locally banded snowfall developing somewhere over
eastern KS and western MO in the vicinity of a stalled 700-hPa
boundary. This would be highly sensitive to small-scale fluctuations
in the height field so it is not necessarily going to come to
fruition. However, a small potential is there for a narrow band of
1"-3" across this corridor, possibly as high as 4" in a few spots
given the banded nature.
With the very high uncertainty, will not make any changes to the
ongoing forecast and will let the overnight shift analyze the full
suite of 00Z models before making the final call on this potential
snow band. But for now, wanted to raise awareness that *if* the
trend of the NAM, RAP and SREF were to continue, then our current
snowfall forecast for the KC area could be too low.
Hawblitzel
&&
.DISCUSSION...
The main focus for the next three days centers on the potential for
accumulating snowfall Saturday night:
Tonight - Saturday:
The strong cold front that will be tracking through the forecast
area tonight through Saturday was situated from northeastern
Nebraska through northwestern Kansas. This front is expected to
start entering northwestern Missouri around midnight tonight and
then be through the forecast area by mid morning. The night will
start rather mild with decent mixing ahead of the front keeping
temperatures ahead of the front in the upper 40s and 50s.
Temperatures will fall into the 20s and 30s behind the front with
temperatures nearly steady during the day Saturday. In fact, we will
likely see our highs early in the day before the cold advection
overwhelms things. Highs on Saturday should range from the upper 20s
in far northwestern Missouri to the lower 40s in parts of central
Missouri.
Saturday night:
As the strong cold advection is occurring, a weak system will move
northwest out of the Southern Plains and track across Arkansas and
southern Missouri. This system will interact with a strong jet
stream moving across the region and for part of the night much of
the forecast area will be the right rear quadrant of the upper jet.
This will enable broad frontogenetic forcing leading to a brief
period of strong upward lift. This will lead to several hours of
snowfall across areas mainly east of Interstate 35. The heaviest
accumulations of snow should be over portions of central Missouri
where as much as 2 inches looks possible given the available
moisture, the intensity of the system and the short duration of the
event itself. Further west, across east central Kansas, west central
Missouri and northwestern Missouri accumulations will be less than
an inch with little or no accumulation expected across far
northwestern Missouri and extreme northeastern Kansas.
Sunday:
This system will be quick-hitting and is expected to be out of the
region by late Sunday morning. As the system exits, skies should
clear out but temperatures will continue to be cold with highs in
the 20s and 30s.
CDB
Medium Range (Monday through Friday)...
Through the medium range, the pattern will gradually transition from
deep troughing over the Plains and eastern Rockies to warmer, more
zonal flow throughout the CONUS. Temperatures on Monday and Tuesday
continue to look colder than average with chilly Canadian air
continuing to flow into the region, then will gradually rise to near
or just above normal for Wednesday through at least Thursday. There
is some degree of disagreement among the longer-range models on the
extent and progression of arctic air into the CONUS by the end of
the work week as a broad, deep trough edges across the Canadian
border, which could strongly impact the temperature forecast. If the
12z ECMWF verifies going into the weekend, very cold temperatures
could slide into the CWA, despite a current consensus of slightly
above normal temperatures for that period. Thus, this will be
something to monitor for significant changes as this time period
draws closer.
No precipitation is expected through this period, as surface high
pressure becomes semi-permanent across the central and southern
Plains and the split jet structure keeps systems confined to far
northern and southeastern portions of the country.
Laflin
&&
.AVIATION...
For the 06Z TAFs...cold front will move through the terminals within
the first couple hours of the forecast with winds veering from wsw
to nw. Pressure gradient remains tight both ahead and immediately
behind the front such that gusty winds expected for at least a few
hours after fropa. Satellite cloud trends and upstream ceilings are
not as pessimistic so will allow for generally VFR conditions
although a few hours of MVFR are expected at KSTJ.
Latest short range models now keying in on the increasing potential
for banded snow a bit further northwest...spreading from east
central KS through west central MO, including the KMCI/KMKC
terminals, shortly after sunset. Model fields suggest a setup
favoring banded snow which would result in a period of several hours
of moderate snow intensity and MVFR/IFR conditions. Since the snow
bands will likely be very narrow the heaviest bands could easily set
up and miss the terminals. However, feel the threat is such that a
PROB group was used to highlight the potential.
MJ
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
155 AM CST SAT JAN 12 2013
.DISCUSSION...UPDATED THE FORECAST TO END THE WIND ADVISORY AND TO
LOWER LOW TEMPERATURES TONIGHT.
&&
.PREV DISCUSSION... /ISSUED 1119 PM CST FRI JAN 11 2013/
AVIATION...06Z KGRI TAF. DRIER LOW TO MID LEVEL AIR IS HELPING
RESTORE VFR CONDITIONS AT THE TERMINAL AND ALTHOUGH TEMPORARY
MVFR CEILINGS CANNOT BE RULED OUT THROUGH 08Z...PREVAILING VFR
CONDITIONS ARE CURRENTLY FORECAST THROUGH THE NEXT 24 HOURS. THE
SURFACE WIND WILL REMAIN STRONG FROM THE NORTHWEST...SUSTAINED AT
AROUND 25KTS AND GUSTING NEAR 30KTS...TO START THE TAF
PERIOD...BUT DECREASE IN INTENSITY THEREAFTER. VISIBILITY
RESTRICTION IS NOT EXPECTED THROUGH THE NEXT 24 HOURS.
PREV DISCUSSION... /ISSUED 843 PM CST FRI JAN 11 2013/
UPDATE...FOG AND LIGHT FREEZING RAIN WHICH WERE OBSERVED AT
VARIOUS POINTS ACROSS THE CWA EARLIER THIS EVENING HAVE SINCE
DISSIPATED. WENT AHEAD AND REMOVED ANY SUCH WORDING FROM THE GRIDS
AND HWO. ANY REPORTS OF BLOWING DUST FROM ACROSS OUR KANSAS
COUNTIES HAVE ALSO CEASED SO WENT AHEAD AND REMOVED SUCH WORDING
FROM THE FORECAST. AS OF 02Z THE LOW LEVEL BAROCLINIC ZONE WAS
LOCATED FROM NEAR KLNK...TO NEAR KHJH...TO NEAR KK61. THE SURFACE
WIND HAS TRANSITIONED TO THE NORTHWEST FOR MOST LOCATIONS ACROSS
OUR CWA AS A RESULT. LOW LEVEL PRESSURE RISES POST-FROPA ARE
INDUCING AN INCREASING LOW LEVEL PRESSURE GRADIENT ACROSS MUCH OF
THE CWA AT THIS HOUR...WITH THE STRONGEST PRESSURE RISES BEING
OBSERVED THROUGH THE TRI-CITIES AREA. A THIN CORRIDOR OF SUSTAINED
WIND NEAR 25KTS IS BEING OBSERVED FROM KAUH...TO KHSI...TO
KGRI...AND SOUTH TO KK82...WITH A SUSTAINED WIND CLOSER TO THE
15-20KT RANGE AT LOCATIONS FARTHER EAST AND WEST. SHORT TERM
GUIDANCE FROM THE RAP SUGGESTS THE LOW LEVEL PRESSURE RISES SHOULD
DIMINISH ACROSS MUCH OF OUR AREA HEADING INTO THE OVERNIGHT HOURS
AND WITH A RESULTANT DECREASE IN THE LOW LEVEL PRESSURE
GRADIENT...THE LOW LEVEL WIND FIELD SHOULD ALSO DIMINISH IN
INTENSITY. THIS IS A SOLUTION ALSO SUPPORTED BY THE NAM AND
OPERATIONAL GFS. THE ONLY EXCEPTION MAY BE ACROSS OUR FAR
NORTH/NORTHEASTERN CWA WHERE THE INCREASED LOW LEVEL PRESSURE
GRADIENT MAY REMAIN INTACT FOR A FEW HOURS LONGER...THUS ALLOWING
FOR A SOMEWHAT STRONGER WIND HEADING INTO THE EARLY MORNING HOURS
SATURDAY. GIVEN ALL THIS...WENT AHEAD AND CANCELLED THE WIND
ADVISORY WHICH WAS IN EFFECT FOR SOME OF OUR KANSAS COUNTIES. ALSO
WENT AHEAD AND PUSHED THE WIND ADVISORY...IN EFFECT FOR OUR
NEBRASKA COUNTIES...NORTH OF I-80 WHERE THE STRONGER LOW LEVEL
PRESSURE GRADIENT IS EXPECTED TO LINGER LONGER. THIS IS A DECISION
WHICH SEEMS A BIT SHAKY RIGHT NOW GIVEN THAT THE TRI-CITIES HAVE
SEEN A DRASTIC INCREASE IN WIND SPEED IN THE LAST HOUR BUT
AGAIN...THE CURRENT BELIEF IS THAT THE WIND WILL DIMINISH WITHIN
ANOTHER HOUR ACROSS THE TRI-CITIES..LEAVING ONLY OUR FAR
NORTH/NORTHEAST AT AN INCREASED RISK OF OBSERVING A WIND WHICH
MEETS WIND ADVISORY CRITERIA. ALSO WENT AHEAD AND TWEAKED HOURLY
TEMPERATURE...DEWPOINT AND SKY GRIDS TO BETTER REFLECT CURRENT
TRENDS.
PREV DISCUSSION... /ISSUED 621 PM CST FRI JAN 11 2013/
UPDATE...EVENING UPPER AIR ANALYSIS PER RAP ANALYSIS DATA
INDICATES LONGWAVE TROUGHING OVER THE WESTERN HALF OF THE
CONUS...WITH RIDGING OVER THE EAST. MID AND UPPER LEVEL JET ENERGY
EXTENDS FROM THE FOUR CORNERS REGION...NORTHEAST ACROSS THE
CENTRAL PLAINS...AND THEN FARTHER NORTHEAST INTO SOUTHERN AND
SOUTHEASTERN CANADA. MID AND UPPER TROPOSPHERIC FLOW IS QUITE
STRONG OVER OUR AREA AS A RESULT...MAXING OUT AT AROUND 150KTS PER
23Z RAP ANALYSIS SOUNDING DATA FROM KGRI. ITS WORTH NOTING THAT
THE LOWER TROPOSPHERE IS ALSO EXHIBITING VERY STRONG
FLOW...50-55KTS ALL THE WAY TO THE TOP OF THE LOW LEVEL INVERSION
NEAR 800MB. WATER VAPOR IMAGERY INDICATES A CLOSED MID LEVEL LOW
OVER WESTERN WYOMING. A MID LEVEL SHORT WAVE IS ALSO NOTED OVER
THE CENTRAL HIGH PLAINS...ADVANCING NORTHEAST ACROSS THE REGION
ALONG THE EASTERN PERIPHERY OF THE CLOSED MID LEVEL LOW. WATER
VAPOR IMAGERY ALSO INDICATES INCREASED VALUES OF MID LEVEL
MOISTURE EXTENDING FROM WEST-TEXAS...NORTHEAST INTO THE CENTRAL
PLAINS AND MID TO UPPER MISSISSIPPI VALLEY. A MID LEVEL DRY
INTRUSION IS ALSO NOTED EXTENDING FROM THE FOUR CORNERS REGION
NORTHEAST INTO THE CENTRAL HIGH PLAINS. AT THE SURFACE A ~992MB
LOW IS NOTED BETWEEN KMCK AND KHLC...WITH AN ASSOCIATED FRONTAL
BOUNDARY EXTENDING EAST/NORTHEAST FROM THE LOW ACROSS CENTRAL AND
NORTHEASTERN NEBRASKA...AND A COLD FRONT EXTENDING WEST/SOUTHWEST
FROM THE LOW INTO NORTHWESTERN KANSAS AND SOUTHEASTERN COLORADO. A
DRY LINE IS ALSO NOTED EXTENDING SOUTH FROM THE LOW ACROSS WESTERN
KANSAS.
BLOWING DUST REMAINED EVIDENT ON VISIBLE SATELLITE IMAGERY UNTIL
SUNSET THIS EVENING BUT AT THIS TIME HAVE NO REASON TO BELIEVE IT
HAS SUBSIDED AS GUSTY WINDS AND MINOR VISIBILITY RESTRICTIONS ARE
STILL BEING REPORTED FROM KPHG TO KHLC. THAT BEING SAID...GIVEN
THE LINGERING SNOWPACK AND WET GROUNDS ACROSS OUR AREA IT APPEARS
UNLIKELY VISIBILITY RESTRICTIONS WILL WORSEN THROUGH THE NEXT
COUPLE OF HOURS...AND WITH VISIBILITY GREATER THAN 1 1/2SM AT
KPHG...AM COMFORTABLE WITH THE BLOWING DUST MENTION IN THE CURRENT
WIND ADVISORY AND HWO. NO PLANS FOR A FORMAL BLOWING DUST ADVISORY
AT THIS TIME.
A THIN CORRIDOR OF DENSE FOG HAS DEVELOPED ALONG THE LOW LEVEL
BAROCLINIC ZONE CURRENTLY PUSHING ACROSS THE CWA. KHSI DROPPED TO
1/4SM FOR A BRIEF TIME THIS AFTERNOON...WITH LOCATIONS FROM KAUH
TO OSCEOLA AND KJYR ALSO REPORTING SIGNIFICANT VISIBILITY
RESTRICTIONS IN FOG THROUGH THE PAST COUPLE OF HOURS. WHAT FOG IS
REALIZED DOES NOT LAST LONG AS IT CONTINUES TO MOVE EAST...BUT
WENT AHEAD AND INSERTED PATCHY DENSE FOG IN THE GRIDS THROUGH 01Z
TO ACCOUNT FOR ONGOING ACTIVITY.
MID LEVEL THERMAL ADVECTION AND MODEST DPVA AHEAD OF THE MID LEVEL
SHORT WAVE OVER THE CENTRAL HIGH PLAINS IS PROMOTING WIDESPREAD
PRECIPITATION OVER WESTERN NEBRASKA...WITH SOME OF THIS
PRECIPITATION MANAGING TO CLIP FAR WEST/NORTHWESTERN PORTIONS OF
OUR CWA IN THE LAST HOUR. PROXIMITY SOUNDINGS FROM OUR
WEST/NORTHWEST CWA PER RAP ANALYSIS DATA SUGGESTS AN ELEVATED WARM
LAYER EXISTS BETWEEN 850 AND 800MB...AND PERIODIC LIGHT FREEZING
RAIN WAS REPORTED IN DAWSON COUNTY IN THE LAST HOUR. GIVEN THE
CURRENT RETURNS FROM KUEX...ANY FREEZING RAIN THAT IS REALIZED
SHOULD REMAIN VERY LIGHT AND SHOULD NOT PRODUCE MUCH IN THE WAY OF
ICE ACCUMULATION. THAT BEING SAID...FELT MORE COMFORTABLE
INTRODUCING LIGHT FREEZING RAIN WORDING TO THE GRIDS AND
HWO...THROUGH 01Z...FOR OUR FAR WEST/NORTHWEST CWA.
WIND ADVISORIES ACROSS OUR AREA REMAIN INTACT WITH NO CHANGES MADE
AT THIS TIME. THOSE HEADLINES WILL BE EVALUATED AND POTENTIALLY
ADJUSTED LATER THIS EVENING. REMAINDER OF THE FORECAST REMAINS IN
GOOD SHAPE...WITH ONLY MINOR TWEAKS MADE TO HOURLY
TEMPERATURE...WIND...AND DEWPOINT GRIDS TO BETTER REFLECT REALITY.
PREV DISCUSSION... /ISSUED 405 PM CST FRI JAN 11 2013/
SHORT TERM...NOW THROUGH SATURDAY
WINTERS COLD RETURNS TO THE CNTRL PLAINS TONIGHT WITH A PERIOD OF
STRONG WIND GUSTS IN THE TRANSITION...
AN SPS WAS ISSUED AT 2032Z FOR THE BLOWING DUST AND WILL PROBABLY
BE UPDATED BY THE BOTTOM OF THE HOUR.
WIND ADVISORIES CONTINUE AS POSTED. NPW WAS UPDATED/SENT AT 324 PM
TO RAISE ADDITIONAL AWARENESS OF BLOWING DUST OVER KS.
NOW: STRONG COLD FRONT IS SAGGING SE THRU CNTRL NEB. IT WAS LAST
SEEN ON THE LNX 88D AT 1825Z JUST NW OF BBW. THE TIMING TOOL BRINGS
IT INTO GRI BY 2230Z. 992 MB LOW WAS TRACKING ALONG THE KS-NEB
BORDER...S OF WHERE IT WAS FCST 24 HRS AGO.
THE FRONT IS AHEAD OF SCHEDULE SO USED THE RAP FOR SHORT-TERM WINDS.
THE 18Z RAP SUGGESTS IT FINALLY CUTS NE THIS EVNG ACROSS ERN NEB.
BLOWING DUST: A BURST OF 33-41 KT WINDS HAS RESULTED IN A LARGE AREA
OF BLOWING DUST THAT ORIGINATED OVER ERN CO. TIMING TOOL WILL BRING
THIS INTO OUR KS COUNTIES AROUND 445 PM AND IT WILL CONTINUE UNTIL
WIND SHIFT ASSOCIATED WITH COLD FRONTAL PASSAGE.
CONTEMPLATED CANCELLING THE WIND ADVISORY FOR N-CNTRL KS SINCE WINDS
HAVE BEEN WELL BELOW ADVISORY SUSTAINED OR GUSTS. BUT GIVEN MULTIPLE
G40 KTS WITH THAT DUST...HAVE CONTINUED ADVISORY.
A LARGE AREA OF STRATUS IS EXPECTED TO SINK S BEHIND THE FRONT TNGT
IN THE WAKE OF THE DEPARTING LOW. HOW FAR S OVC EXTENDS REMAINS
UNCERTAIN GIVEN DOWNSLOPING WINDS WILL TEND TO BREAK IT UP.
WIND: 3 HR PRES RISES ARE ONLY 3 MB OVER THE NEB PANHANDLE AT 21Z.
THE NAM IS OVER ESTIMATING THIS BY 5 MB AND THE RAP BY 3 MB. THINK
THE TREND IS RIGHT WITH EXPANDING/INCREASING PRES RISES AS THE LOW
ACCELERATES NEWD THIS EVE...BUT THE MAGNITUDE MAY BE OVERDONE.
CONFIDENCE IS ABOVE AVERAGE FOR VERIFYING THE ADVISORY OVER N-CNTRL
KS AHEAD OF THE FRONT. IT/S TAKEN ALL DAY BUT IT WILL VERIFY
22Z-03Z. BEHIND THE FRONT HAVE YET TO SEE ADVISORY LEVEL WINDS
DEVELOP. LOW-LEVELS WILL BECOME UNSTABLE IN CAA THIS EVE AND BUT
THIS APPEARS A MARGINAL WIND EVENT SO VERIFYING NEB WIND ADVISORY IS
BELOW AVERAGE ALONG AND S OF I-80. BEST CHANCE FOR A ONE-TIME 45 MPH
GUST WILL BE N OF THE TRI-CITIES. THE BEST CHANCE FOR VERIFYING
ALONG AND S OF I-80 WILL PROBABLY BE A BRIEF PERIOD OF SUSTAINED
WINDS OF 30 MPH.
TNGT: M/CLOUDY WITH BLUSTERY NW WINDS. SOME FLURRIES OR BRIEF SHSN
WILL OCCUR 6PM-12AM IN PULSE OF CAA. TEMP GUIDANCE WAS IN GOOD
AGREEMENT AND USED THE CONSENSUS OF ALL GUIDANCE WHICH BASICALLY
PUTS TEMPS NEAR NORMAL.
SAT: A MIX OF CLOUDS/SUN. UNSURE HOW MUCH STRATOCU GETS TRAPPED
UNDER FRONTAL INVERSION. HAVE ALREADY INCREASED CLOUDS ABOVE
PREVIOUS GID FCST AND IF NAM BUFKIT IS RIGHT THAN WE WILL BE TOO
LOW ON CLOUD COVER. REGARDLESS...PATCHES JET STREAM CIRRUS WILL
KEEP THE SKY AT LEAST P/CLOUDY. STILL A BLUSTERY NW WIND WITH GUST
UP TO 30 MPH FORENOON. TEMPS ARE NAM 2M TEMPS WHICH IS CLOSE TO
THE PREVIOUS FCST...ABOUT 12F BELOW NORMAL.
LONG TERM...SATURDAY NIGHT THROUGH FRIDAY. THIS WILL LIKELY BE A
DRY PERIOD WITH TEMPERATURES GENERALLY WARMING THROUGH AT LEAST
WEDNESDAY. MORE UNCERTAINTY ENTERS THE PICTURE BY THURSDAY AND
FRIDAY.
SATURDAY NIGHT THROUGH MONDAY...A COLD AREA OF ARCTIC HIGH PRESSURE
WILL BEGIN TO SLIDE INTO THE PLAINS SATURDAY NIGHT INTO SUNDAY AND
REMAIN THROUGH AT LEAST MONDAY. THERE WILL BE A LARGE UPPER TROUGH
SITUATED OVER THE PLAINS BUT ALL OF THE MOISTURE WILL BE AT THE
LEADING EDGE OF THIS TROUGH AND WELL OFF TO OUR EAST. HIGH
TEMPERATURES WILL BE STUCK IN THE 20S ON SUNDAY AND POSSIBLY MONDAY
AS WELL. SOME AREAS THAT ARE COMPLETELY FREE OF SNOW COVER MAY REACH
THE LOWER 30S ON MONDAY.
TUESDAY AND WEDNESDAY...THE 12Z ECMWF PUSHES THE SFC HIGH OFF TO OUR
SOUTH ALLOWING FOR WEST SOUTHWEST DOWNSLOPE SFC WINDS. THE SHALLOW
COLD AIR WILL GRADUALLY MODERATE WITH HIGH TEMPERATURES BACK INTO
THE 30S ON TUESDAY AND PROBABLY 40S BY WEDNESDAY.
THURSDAY THROUGH FRIDAY...THERE IS A SUBSTANTIAL AMOUNT OF MODEL
UNCERTAINTY WITH REGARD TO TEMPERATURES. HOWEVER...THERE IS GOOD
MODEL AGREEMENT IN DRY CONDITIONS. THE ECMWF BRINGS A COLD FRONT
THROUGH WEDNESDAY NIGHT WITH STRONG COLD AIR ADVECTION ON THURSDAY.
THE 850 MB TEMPERATURES THURSDAY EVENING RANGE FROM -15C ON THE 12Z
ECMWF TO 5C ON THE 12Z GFS FOR A SIGNIFICANT 20C DEGREE SPREAD. THE
OFFICIAL FORECAST IS SOMEWHERE IN THE MIDDLE OF THESE TWO MODELS
CALLING FOR ABOVE FREEZING HIGHS IN THE UPPER 30S TO LOWER 40S.
HOWEVER...THESE HIGHS MAY VERY WELL BE TOO WARM. THE ONGOING
STRATOSPHERIC WARMING EVENT WILL LIKELY RESULT IN THE TRANSITION TO
A NEGATIVE ARCTIC OSCILLATION PATTERN...WHICH TENDS TO BRING THE
COLD AIR DOWN OUT OF CANADA INTO THE EASTERN TWO THIRDS OF THE
CONUS. THEREFORE...I WOULD LEAN MORE TOWARDS THE ECWMF AND THE
POSSIBILITY OF COLDER TEMPERATURES THAN WHAT WE ARE OFFICIALLY
CALLING FOR AS THIS BETTER FITS THE -AO PATTERN. IF THE 12Z ECMWF
COLDER TREND CONTINUES...WE WILL NEED TO BE LOWERING OUR THURSDAY
AND FRIDAY HIGH TEMPERATURES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
DISCUSSION (UPDATE)...HEINLEIN
AVIATION/EARLIER UPDATES...BRYANT
SHORT TERM...HALBLAUB
LONG TERM...WESELY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1119 PM CST FRI JAN 11 2013
.AVIATION...06Z KGRI TAF. DRIER LOW TO MID LEVEL AIR IS HELPING
RESTORE VFR CONDITIONS AT THE TERMINAL AND ALTHOUGH TEMPORARY
MVFR CEILINGS CANNOT BE RULED OUT THROUGH 08Z...PREVAILING VFR
CONDITIONS ARE CURRENTLY FORECAST THROUGH THE NEXT 24 HOURS. THE
SURFACE WIND WILL REMAIN STRONG FROM THE NORTHWEST...SUSTAINED AT
AROUND 25KTS AND GUSTING NEAR 30KTS...TO START THE TAF
PERIOD...BUT DECREASE IN INTENSITY THEREAFTER. VISIBILITY
RESTRICTION IS NOT EXPECTED THROUGH THE NEXT 24 HOURS.
&&
.PREV DISCUSSION... /ISSUED 843 PM CST FRI JAN 11 2013/
UPDATE...FOG AND LIGHT FREEZING RAIN WHICH WERE OBSERVED AT
VARIOUS POINTS ACROSS THE CWA EARLIER THIS EVENING HAVE SINCE
DISSIPATED. WENT AHEAD AND REMOVED ANY SUCH WORDING FROM THE GRIDS
AND HWO. ANY REPORTS OF BLOWING DUST FROM ACROSS OUR KANSAS
COUNTIES HAVE ALSO CEASED SO WENT AHEAD AND REMOVED SUCH WORDING
FROM THE FORECAST. AS OF 02Z THE LOW LEVEL BAROCLINIC ZONE WAS
LOCATED FROM NEAR KLNK...TO NEAR KHJH...TO NEAR KK61. THE SURFACE
WIND HAS TRANSITIONED TO THE NORTHWEST FOR MOST LOCATIONS ACROSS
OUR CWA AS A RESULT. LOW LEVEL PRESSURE RISES POST-FROPA ARE
INDUCING AN INCREASING LOW LEVEL PRESSURE GRADIENT ACROSS MUCH OF
THE CWA AT THIS HOUR...WITH THE STRONGEST PRESSURE RISES BEING
OBSERVED THROUGH THE TRI-CITIES AREA. A THIN CORRIDOR OF SUSTAINED
WIND NEAR 25KTS IS BEING OBSERVED FROM KAUH...TO KHSI...TO
KGRI...AND SOUTH TO KK82...WITH A SUSTAINED WIND CLOSER TO THE
15-20KT RANGE AT LOCATIONS FARTHER EAST AND WEST. SHORT TERM
GUIDANCE FROM THE RAP SUGGESTS THE LOW LEVEL PRESSURE RISES SHOULD
DIMINISH ACROSS MUCH OF OUR AREA HEADING INTO THE OVERNIGHT HOURS
AND WITH A RESULTANT DECREASE IN THE LOW LEVEL PRESSURE
GRADIENT...THE LOW LEVEL WIND FIELD SHOULD ALSO DIMINISH IN
INTENSITY. THIS IS A SOLUTION ALSO SUPPORTED BY THE NAM AND
OPERATIONAL GFS. THE ONLY EXCEPTION MAY BE ACROSS OUR FAR
NORTH/NORTHEASTERN CWA WHERE THE INCREASED LOW LEVEL PRESSURE
GRADIENT MAY REMAIN INTACT FOR A FEW HOURS LONGER...THUS ALLOWING
FOR A SOMEWHAT STRONGER WIND HEADING INTO THE EARLY MORNING HOURS
SATURDAY. GIVEN ALL THIS...WENT AHEAD AND CANCELLED THE WIND
ADVISORY WHICH WAS IN EFFECT FOR SOME OF OUR KANSAS COUNTIES. ALSO
WENT AHEAD AND PUSHED THE WIND ADVISORY...IN EFFECT FOR OUR
NEBRASKA COUNTIES...NORTH OF I-80 WHERE THE STRONGER LOW LEVEL
PRESSURE GRADIENT IS EXPECTED TO LINGER LONGER. THIS IS A DECISION
WHICH SEEMS A BIT SHAKY RIGHT NOW GIVEN THAT THE TRI-CITIES HAVE
SEEN A DRASTIC INCREASE IN WIND SPEED IN THE LAST HOUR BUT
AGAIN...THE CURRENT BELIEF IS THAT THE WIND WILL DIMINISH WITHIN
ANOTHER HOUR ACROSS THE TRI-CITIES..LEAVING ONLY OUR FAR
NORTH/NORTHEAST AT AN INCREASED RISK OF OBSERVING A WIND WHICH
MEETS WIND ADVISORY CRITERIA. ALSO WENT AHEAD AND TWEAKED HOURLY
TEMPERATURE...DEWPOINT AND SKY GRIDS TO BETTER REFLECT CURRENT
TRENDS.
PREV DISCUSSION... /ISSUED 621 PM CST FRI JAN 11 2013/
UPDATE...EVENING UPPER AIR ANALYSIS PER RAP ANALYSIS DATA
INDICATES LONGWAVE TROUGHING OVER THE WESTERN HALF OF THE
CONUS...WITH RIDGING OVER THE EAST. MID AND UPPER LEVEL JET ENERGY
EXTENDS FROM THE FOUR CORNERS REGION...NORTHEAST ACROSS THE
CENTRAL PLAINS...AND THEN FARTHER NORTHEAST INTO SOUTHERN AND
SOUTHEASTERN CANADA. MID AND UPPER TROPOSPHERIC FLOW IS QUITE
STRONG OVER OUR AREA AS A RESULT...MAXING OUT AT AROUND 150KTS PER
23Z RAP ANALYSIS SOUNDING DATA FROM KGRI. ITS WORTH NOTING THAT
THE LOWER TROPOSPHERE IS ALSO EXHIBITING VERY STRONG
FLOW...50-55KTS ALL THE WAY TO THE TOP OF THE LOW LEVEL INVERSION
NEAR 800MB. WATER VAPOR IMAGERY INDICATES A CLOSED MID LEVEL LOW
OVER WESTERN WYOMING. A MID LEVEL SHORT WAVE IS ALSO NOTED OVER
THE CENTRAL HIGH PLAINS...ADVANCING NORTHEAST ACROSS THE REGION
ALONG THE EASTERN PERIPHERY OF THE CLOSED MID LEVEL LOW. WATER
VAPOR IMAGERY ALSO INDICATES INCREASED VALUES OF MID LEVEL
MOISTURE EXTENDING FROM WEST-TEXAS...NORTHEAST INTO THE CENTRAL
PLAINS AND MID TO UPPER MISSISSIPPI VALLEY. A MID LEVEL DRY
INTRUSION IS ALSO NOTED EXTENDING FROM THE FOUR CORNERS REGION
NORTHEAST INTO THE CENTRAL HIGH PLAINS. AT THE SURFACE A ~992MB
LOW IS NOTED BETWEEN KMCK AND KHLC...WITH AN ASSOCIATED FRONTAL
BOUNDARY EXTENDING EAST/NORTHEAST FROM THE LOW ACROSS CENTRAL AND
NORTHEASTERN NEBRASKA...AND A COLD FRONT EXTENDING WEST/SOUTHWEST
FROM THE LOW INTO NORTHWESTERN KANSAS AND SOUTHEASTERN COLORADO. A
DRY LINE IS ALSO NOTED EXTENDING SOUTH FROM THE LOW ACROSS WESTERN
KANSAS.
BLOWING DUST REMAINED EVIDENT ON VISIBLE SATELLITE IMAGERY UNTIL
SUNSET THIS EVENING BUT AT THIS TIME HAVE NO REASON TO BELIEVE IT
HAS SUBSIDED AS GUSTY WINDS AND MINOR VISIBILITY RESTRICTIONS ARE
STILL BEING REPORTED FROM KPHG TO KHLC. THAT BEING SAID...GIVEN
THE LINGERING SNOWPACK AND WET GROUNDS ACROSS OUR AREA IT APPEARS
UNLIKELY VISIBILITY RESTRICTIONS WILL WORSEN THROUGH THE NEXT
COUPLE OF HOURS...AND WITH VISIBILITY GREATER THAN 1 1/2SM AT
KPHG...AM COMFORTABLE WITH THE BLOWING DUST MENTION IN THE CURRENT
WIND ADVISORY AND HWO. NO PLANS FOR A FORMAL BLOWING DUST ADVISORY
AT THIS TIME.
A THIN CORRIDOR OF DENSE FOG HAS DEVELOPED ALONG THE LOW LEVEL
BAROCLINIC ZONE CURRENTLY PUSHING ACROSS THE CWA. KHSI DROPPED TO
1/4SM FOR A BRIEF TIME THIS AFTERNOON...WITH LOCATIONS FROM KAUH
TO OSCEOLA AND KJYR ALSO REPORTING SIGNIFICANT VISIBILITY
RESTRICTIONS IN FOG THROUGH THE PAST COUPLE OF HOURS. WHAT FOG IS
REALIZED DOES NOT LAST LONG AS IT CONTINUES TO MOVE EAST...BUT
WENT AHEAD AND INSERTED PATCHY DENSE FOG IN THE GRIDS THROUGH 01Z
TO ACCOUNT FOR ONGOING ACTIVITY.
MID LEVEL THERMAL ADVECTION AND MODEST DPVA AHEAD OF THE MID LEVEL
SHORT WAVE OVER THE CENTRAL HIGH PLAINS IS PROMOTING WIDESPREAD
PRECIPITATION OVER WESTERN NEBRASKA...WITH SOME OF THIS
PRECIPITATION MANAGING TO CLIP FAR WEST/NORTHWESTERN PORTIONS OF
OUR CWA IN THE LAST HOUR. PROXIMITY SOUNDINGS FROM OUR
WEST/NORTHWEST CWA PER RAP ANALYSIS DATA SUGGESTS AN ELEVATED WARM
LAYER EXISTS BETWEEN 850 AND 800MB...AND PERIODIC LIGHT FREEZING
RAIN WAS REPORTED IN DAWSON COUNTY IN THE LAST HOUR. GIVEN THE
CURRENT RETURNS FROM KUEX...ANY FREEZING RAIN THAT IS REALIZED
SHOULD REMAIN VERY LIGHT AND SHOULD NOT PRODUCE MUCH IN THE WAY OF
ICE ACCUMULATION. THAT BEING SAID...FELT MORE COMFORTABLE
INTRODUCING LIGHT FREEZING RAIN WORDING TO THE GRIDS AND
HWO...THROUGH 01Z...FOR OUR FAR WEST/NORTHWEST CWA.
WIND ADVISORIES ACROSS OUR AREA REMAIN INTACT WITH NO CHANGES MADE
AT THIS TIME. THOSE HEADLINES WILL BE EVALUATED AND POTENTIALLY
ADJUSTED LATER THIS EVENING. REMAINDER OF THE FORECAST REMAINS IN
GOOD SHAPE...WITH ONLY MINOR TWEAKS MADE TO HOURLY
TEMPERATURE...WIND...AND DEWPOINT GRIDS TO BETTER REFLECT REALITY.
PREV DISCUSSION... /ISSUED 405 PM CST FRI JAN 11 2013/
SHORT TERM...NOW THROUGH SATURDAY
WINTERS COLD RETURNS TO THE CNTRL PLAINS TONIGHT WITH A PERIOD OF
STRONG WIND GUSTS IN THE TRANSITION...
AN SPS WAS ISSUED AT 2032Z FOR THE BLOWING DUST AND WILL PROBABLY
BE UPDATED BY THE BOTTOM OF THE HOUR.
WIND ADVISORIES CONTINUE AS POSTED. NPW WAS UPDATED/SENT AT 324 PM
TO RAISE ADDITIONAL AWARENESS OF BLOWING DUST OVER KS.
NOW: STRONG COLD FRONT IS SAGGING SE THRU CNTRL NEB. IT WAS LAST
SEEN ON THE LNX 88D AT 1825Z JUST NW OF BBW. THE TIMING TOOL BRINGS
IT INTO GRI BY 2230Z. 992 MB LOW WAS TRACKING ALONG THE KS-NEB
BORDER...S OF WHERE IT WAS FCST 24 HRS AGO.
THE FRONT IS AHEAD OF SCHEDULE SO USED THE RAP FOR SHORT-TERM WINDS.
THE 18Z RAP SUGGESTS IT FINALLY CUTS NE THIS EVNG ACROSS ERN NEB.
BLOWING DUST: A BURST OF 33-41 KT WINDS HAS RESULTED IN A LARGE AREA
OF BLOWING DUST THAT ORIGINATED OVER ERN CO. TIMING TOOL WILL BRING
THIS INTO OUR KS COUNTIES AROUND 445 PM AND IT WILL CONTINUE UNTIL
WIND SHIFT ASSOCIATED WITH COLD FRONTAL PASSAGE.
CONTEMPLATED CANCELLING THE WIND ADVISORY FOR N-CNTRL KS SINCE WINDS
HAVE BEEN WELL BELOW ADVISORY SUSTAINED OR GUSTS. BUT GIVEN MULTIPLE
G40 KTS WITH THAT DUST...HAVE CONTINUED ADVISORY.
A LARGE AREA OF STRATUS IS EXPECTED TO SINK S BEHIND THE FRONT TNGT
IN THE WAKE OF THE DEPARTING LOW. HOW FAR S OVC EXTENDS REMAINS
UNCERTAIN GIVEN DOWNSLOPING WINDS WILL TEND TO BREAK IT UP.
WIND: 3 HR PRES RISES ARE ONLY 3 MB OVER THE NEB PANHANDLE AT 21Z.
THE NAM IS OVER ESTIMATING THIS BY 5 MB AND THE RAP BY 3 MB. THINK
THE TREND IS RIGHT WITH EXPANDING/INCREASING PRES RISES AS THE LOW
ACCELERATES NEWD THIS EVE...BUT THE MAGNITUDE MAY BE OVERDONE.
CONFIDENCE IS ABOVE AVERAGE FOR VERIFYING THE ADVISORY OVER N-CNTRL
KS AHEAD OF THE FRONT. IT/S TAKEN ALL DAY BUT IT WILL VERIFY
22Z-03Z. BEHIND THE FRONT HAVE YET TO SEE ADVISORY LEVEL WINDS
DEVELOP. LOW-LEVELS WILL BECOME UNSTABLE IN CAA THIS EVE AND BUT
THIS APPEARS A MARGINAL WIND EVENT SO VERIFYING NEB WIND ADVISORY IS
BELOW AVERAGE ALONG AND S OF I-80. BEST CHANCE FOR A ONE-TIME 45 MPH
GUST WILL BE N OF THE TRI-CITIES. THE BEST CHANCE FOR VERIFYING
ALONG AND S OF I-80 WILL PROBABLY BE A BRIEF PERIOD OF SUSTAINED
WINDS OF 30 MPH.
TNGT: M/CLOUDY WITH BLUSTERY NW WINDS. SOME FLURRIES OR BRIEF SHSN
WILL OCCUR 6PM-12AM IN PULSE OF CAA. TEMP GUIDANCE WAS IN GOOD
AGREEMENT AND USED THE CONSENSUS OF ALL GUIDANCE WHICH BASICALLY
PUTS TEMPS NEAR NORMAL.
SAT: A MIX OF CLOUDS/SUN. UNSURE HOW MUCH STRATOCU GETS TRAPPED
UNDER FRONTAL INVERSION. HAVE ALREADY INCREASED CLOUDS ABOVE
PREVIOUS GID FCST AND IF NAM BUFKIT IS RIGHT THAN WE WILL BE TOO
LOW ON CLOUD COVER. REGARDLESS...PATCHES JET STREAM CIRRUS WILL
KEEP THE SKY AT LEAST P/CLOUDY. STILL A BLUSTERY NW WIND WITH GUST
UP TO 30 MPH FORENOON. TEMPS ARE NAM 2M TEMPS WHICH IS CLOSE TO
THE PREVIOUS FCST...ABOUT 12F BELOW NORMAL.
LONG TERM...SATURDAY NIGHT THROUGH FRIDAY. THIS WILL LIKELY BE A
DRY PERIOD WITH TEMPERATURES GENERALLY WARMING THROUGH AT LEAST
WEDNESDAY. MORE UNCERTAINTY ENTERS THE PICTURE BY THURSDAY AND
FRIDAY.
SATURDAY NIGHT THROUGH MONDAY...A COLD AREA OF ARCTIC HIGH PRESSURE
WILL BEGIN TO SLIDE INTO THE PLAINS SATURDAY NIGHT INTO SUNDAY AND
REMAIN THROUGH AT LEAST MONDAY. THERE WILL BE A LARGE UPPER TROUGH
SITUATED OVER THE PLAINS BUT ALL OF THE MOISTURE WILL BE AT THE
LEADING EDGE OF THIS TROUGH AND WELL OFF TO OUR EAST. HIGH
TEMPERATURES WILL BE STUCK IN THE 20S ON SUNDAY AND POSSIBLY MONDAY
AS WELL. SOME AREAS THAT ARE COMPLETELY FREE OF SNOW COVER MAY REACH
THE LOWER 30S ON MONDAY.
TUESDAY AND WEDNESDAY...THE 12Z ECMWF PUSHES THE SFC HIGH OFF TO OUR
SOUTH ALLOWING FOR WEST SOUTHWEST DOWNSLOPE SFC WINDS. THE SHALLOW
COLD AIR WILL GRADUALLY MODERATE WITH HIGH TEMPERATURES BACK INTO
THE 30S ON TUESDAY AND PROBABLY 40S BY WEDNESDAY.
THURSDAY THROUGH FRIDAY...THERE IS A SUBSTANTIAL AMOUNT OF MODEL
UNCERTAINTY WITH REGARD TO TEMPERATURES. HOWEVER...THERE IS GOOD
MODEL AGREEMENT IN DRY CONDITIONS. THE ECMWF BRINGS A COLD FRONT
THROUGH WEDNESDAY NIGHT WITH STRONG COLD AIR ADVECTION ON THURSDAY.
THE 850 MB TEMPERATURES THURSDAY EVENING RANGE FROM -15C ON THE 12Z
ECMWF TO 5C ON THE 12Z GFS FOR A SIGNIFICANT 20C DEGREE SPREAD. THE
OFFICIAL FORECAST IS SOMEWHERE IN THE MIDDLE OF THESE TWO MODELS
CALLING FOR ABOVE FREEZING HIGHS IN THE UPPER 30S TO LOWER 40S.
HOWEVER...THESE HIGHS MAY VERY WELL BE TOO WARM. THE ONGOING
STRATOSPHERIC WARMING EVENT WILL LIKELY RESULT IN THE TRANSITION TO
A NEGATIVE ARCTIC OSCILLATION PATTERN...WHICH TENDS TO BRING THE
COLD AIR DOWN OUT OF CANADA INTO THE EASTERN TWO THIRDS OF THE
CONUS. THEREFORE...I WOULD LEAN MORE TOWARDS THE ECWMF AND THE
POSSIBILITY OF COLDER TEMPERATURES THAN WHAT WE ARE OFFICIALLY
CALLING FOR AS THIS BETTER FITS THE -AO PATTERN. IF THE 12Z ECMWF
COLDER TREND CONTINUES...WE WILL NEED TO BE LOWERING OUR THURSDAY
AND FRIDAY HIGH TEMPERATURES.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...WIND ADVISORY UNTIL 1 AM CST SATURDAY FOR NEZ039>041-046>049.
KS...NONE.
&&
$$
AVIATION/UPDATES...BRYANT
SHORT...HALBLAUB
LONG...WESELY
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
955 AM EST SAT JAN 12 2013
.UPDATE (REST OF THE WEEKEND)...
15Z WATER VAPOR AND H4 RAP ANALYSIS SHOW A HIGHLY AMPLIFIED PATTERN
IN PLACE OVER THE CONUS THIS MORNING. LUCKILY FOR US...THE WARM AND
FAIR WEATHER SIDE OF THIS AMPLIFICATION RESIDES OVER OUR HEADS...AND
WILL CONTINUE TO DO SO FOR THE REMAINDER OF THE WEEKEND. LARGE SCALE
PATTERN CONSISTS OF DEEP LONGWAVE TROUGHING IN PLACE OVER THE
WESTERN HALF OF THE NATION FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING
EXTENDING FROM THE EASTERN GULF OF MEXICO NORTHWARD ALONG THE ENTIRE
EASTERN SEABOARD. WV IMAGERY SHOWS AN INTERESTING SPIN / LEFTOVER
MCV RUNNING THROUGH THE RIDGE THIS MORNING OVER NORTHERN
FLORIDA...LIKELY LEFTOVER FROM CONVECTION TO OUR WEST DURING THE
PAST COUPLE DAYS. THIS FEATURE IS VISUALLY INTERESTING...BUT WILL
HAVE LITTLE IMPACT ON OUR LOCAL WEATHER OTHER THAN SOME WEAK
NVA/ENHANCE SUPPRESSION OVER THE AREA INTO THE EARLY AFTERNOON. THIS
SUPPRESSION OVER-TOP THE LOW LEVEL MOISTURE MAY HAVE AIDED SOME OF
THE FOG FORMATION EARLIER THIS MORNING...BUT NOW THAT DIURNAL
HEATING HAS COMMENCED...ANY LEFTOVER VISIBILITY RESTRICTIONS WILL
SOON BE A DISTANT MEMORY. 12Z KTBW SOUNDING PROFILE SHOWS THE
INFLUENCE OF THE UPPER RIDGE WITH A DISTINCT SUBSIDENCE INVERSION
ABOVE 850MB THIS MORNING. COLUMN IS QUITE DRY ABOVE THIS LEVEL...BUT
SEEING ENOUGH MOISTURE UNDERNEATH TO ONCE AGAIN FORCE A SCT-BKN
SHALLOW CU FIELD FOR THE AFTERNOON HOURS.
MADE A FEW TWEAKS TO THE AFTERNOON TEMPERATURE CURVE AND SKY COVER
GRIDS...BUT OTHERWISE INHERITED FORECAST APPEARS ON TRACK FOR
ANOTHER FAIR AND UNSEASONABLY WARM JANUARY DAY.
TONIGHT/SUNDAY...STACKED RIDGING WILL KEEP THE WEATHER PATTERN
UNCHANGED THROUGH THE REMAINDER OF THE WEEKEND. OVERNIGHT LOWS WILL
MAINLY BE IN THE LOWER/MID 60S AT THE COAST AND MIDDLE 50S TO AROUND
60 INLAND BY SUNRISE. DAYTIME HIGHS CLIMB BACK INTO THE LOWER 80S
FOR MANY LOCATIONS SUNDAY AFTERNOON. LOCAL GRADIENT DOES SLACKEN A
BIT DURING THE DAY ON SUNDAY...AND DUE TO THE UNUSUALLY STRONG LAND
BASED HEATING...MAY SEE A FEEBLE SEA-BREEZE DEVELOP DURING THE
AFTERNOON...ESPECIALLY FROM PINELLAS COUNTY NORTHWARD. IF THIS WEAK
ONSHORE FLOW DOES DEVELOP THEN THE IMMEDIATE COAST WOULD END UP A
FEW DEGREES COOLER. REGARDLESS WILL BE FORECASTING ABOVE NORMAL
TEMPERATURES FOR ALL.
&&
.AVIATION...
EXPECT VFR CONDITIONS WITH OCNL BROKEN CIGS ABOVE 3000 FEET THROUGH
08Z. MVFR OR IFR VISIBILITIES IN FOG POSSIBLE AFTER 08Z SUNDAY.
&&
.MARINE...
SURFACE HIGH PRESSURE OFFSHORE OF THE SOUTHEAST U.S. WILL REMAIN IN
PLACE THROUGH EARLY NEXT WEEK WITH A SOUTHEAST WIND FLOW CONTINUING.
THIS HIGH WILL SHIFT SOUTH AND EAST OF THE REGION ON TUESDAY AS A
COLD FRONT MOVES INTO THE NORTHERN GULF WATERS. THIS FRONT WILL THEN
MOVE SOUTH THROUGH THE WATERS ON WEDNESDAY SHIFTING WINDS TO THE
NORTHWEST AND NORTH IN ITS WAKE.
&&
.CLIMATE...
HERE ARE SOME RECORD HIGH TEMPERATURES FOR TODAY.
TAMPA INTERNATIONAL 82 SET BACK IN 1989
SAINT PETERSBURG CLEARWATER 81 SET BACK IN 2005
SARASOTA/BRADENTON 86 SET BACK IN 1993
LAKELAND 85 SET BACK IN 1993
BROOKSVILLE 81 SET BACK IN 2008
FORT MYERS 85 SET BACK IN 1993
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 82 64 81 65 / 0 10 0 10
FMY 83 63 82 62 / 0 10 0 0
GIF 82 61 82 62 / 0 10 0 10
SRQ 80 62 80 61 / 0 10 0 10
BKV 83 55 82 55 / 0 10 0 10
SPG 79 65 79 65 / 0 10 0 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
UPDATE/MARINE...MROCZKA
AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
528 AM EST SAT JAN 12 2013
.SHORT TERM... /TODAY THROUGH SUNDAY NIGHT/
HIGHLY COMPLEX MID/UPR TROPOSPHERIC WAVE INTERACTIONS/DEFORMATIONS
UNDERWAY ACRS UPR PLAINS BLIZZARD/SNOWSTORM IN PROGRESS. HIGHLY
BUCKLED FLOW PATTERN PER RIDGE AXIS ALONG WRN ATL AND 140W. THIS
ALONG WITH STRONGLY MERIDIONAL FLOW DOWNSTREAM OF INTMTN/CNTL
ROCKIES TROF WITH NMRS SHORTWAVES TRANSLATING THROUGH...FIRST
EJECTING FM NRN OLD MEXICO ATTM AND OTHER SIG WAVE ACRS WRN ALB TO
HELP REPLANT BASE ACRS THE SWRN STATES THROUGH THE SHORT TERM
PD...AFFORDING STRONG PERMANENCE IN THE SHORT TERM WITH A PRIMARILY
STRONG POS TILT TROF AXIS...PRESENTING AS A SLOW/STALLED EULARIAN
STREAM SYSTEM WITH EMBEDDED HIGH VELOCITY LAGRANGIAN SUBSCALE
FEATURES. GIVEN PRECONDITIONING WITH DEEP SRLY/SWRLY FLOW DOWNSTREAM
TO PROVIDE QUITE SECURE WARM/HIGH BULK MOISTURE AIRMASS /PWAT AOA
1.25-1.4 INCHES/ INTO SRN GRTLKS/OHIO VALLEY...WITH CONTINUAL LLVL
GOMEX SUSTENANCE FEED BENEATH SUBTROPICAL MOISTURE SWEEP IN THE
MID/UP LVLS.
SRN TAIL OF NRN PLAINS UPSTREAM SFC FNTL WAVE TO APPROACH LATE
TODAY...THOUGH IN A STRONGLY LYTIC FASHION ALONG ITS SRN EXTENSION
WITH BEST DEEPLY FORCED ASCENT HELD AT ABEYANCE WELL N/NW OF CWA.
SLIGHT DELAY IN ONSET OF PRECIP ASSOCD WITH TIMING OF SWRN TX FNTL
WAVE TONIGHT...CERTAINLY NOT WRT REVERSAL OF TROF TILT. SFC LOW ACRS
CNTL ARKANSAS AT F24...THEN QUICKLY INTO WRN LK ERIE BY 12 UTC SUN.
STRONG FGEN RESPONSE AMID WARM/MOIST AIRMASS TO RESULT IN LARGE RAIN
SWATH. SOME CONCERN WRT NEED OF FLOOD WATCH FOR MAUMEE AND WABASH
BASINS...HOWEVER ATTM SPEED OF SYSTEM ALONG WITH STRONG INDICATIONS
OF QUICK TAPER DURING THE DAY SUNDAY. FOR NOW WITH PRIOR RAFL/RUNOFF
RESPONSES BEING RELATIVELY MUTED...WILL SIMPLY ADDRESS IN ESF/HWO. A
SFC LOW TRACK POTNL THROUGH HEART AFOREMENTIONED BASINS GIVES
DISFAVOR FOR SECONDARY DEFORMATION ZONE ENHANCED PRECIP SWATCH.
AGAIN POSTFNTL UNDERCUT OF COLD AIR /DEPTH MAGNITUDE AND
POSITION/ OF DIRE IMPORTANCE WRT PTYPE. QUICK/ARDENT LOSS OF
MSTR/SATURATION DEPTH IN DRY SLOT PERHAPS SAVING GRACE AS ANTICIPATE
WINTRY MIX ACCUMS AOB HEADLINES AND/OR INCRSLY CONDITIONAL IN
NATURE. WL CERTAINLY ADDRESS POTNL/IN HWO.
MUTED LAKE RESPONSE WITH STRONGLY SHEARED IN CLOUD FLOW THAT
QUICKLY BACKS WRLY...SUPPORTING A SUBVERSIVE DRY UNDERCUT TO ANY
BANDS AS CANADIAN/PLAINS AIRMASS BEGINS TO QUICKLY BECOME ENTRAINED
THROUGH WI/SRN LK MI SUN EVE/NIGHT. DEPTH OF MSTR ALSO NEGATIVE
WITH DGZ FAILURE NOTED...PERHAPS EVEN AN ICE CRYSTAL NUCLAETION
FAILURE PSBLTY SUNDAY AFTN. ABOVE FACTORS OVERLAIN WITH OVERALL
LAME LAKE INDUCED THERMAL STABILITY...SUGGESTS LOW CHC SHSN AND/OR
SCT FLURRIES MENTION BEST ATTM.
&&
.LONG TERM...MONDAY THROUGH FRIDAY.
N/NW FLOW WILL HOLD THROUGH THE PERIOD WITH TEMPS NEAR OR BELOW
NORMAL. INITIALLY...DELTA T`S FAVORABLE FOR SOME LAKE EFFECT CLOUD
AND SNOW SHOWERS. HOWEVER...MSTR PROFILES QUITE ANEMIC AND WHAT DOES
EXIST IS MAINLY CONFINED NORTH OF THE FORECAST AREA. HAVE NUDGED
POPS UP TO 14 PERCENT ACROSS MI COUNTIES BUT NO INTRODUCTION OF ANY
WX MENTION AT THIS POINT.
A SERIES OF WEAK WAVES WILL MOVE THROUGH THE FLOW...IMPACTING MAINLY
THE NORTHERN PLAINS/GREAT LAKES AREAS. EACH WAVE WILL ATTEMPT TO
REINFORCE THE COLD AIR ACROSS THE REGION. MODELS VARY ON HOW FAR
SOUTH EACH OF THESE INTRUSIONS WILL BE. AT THIS POINT...FEW CHANGES
TO PAST GRIDS. ALLBLEND CONTINUES TO PLACE IN SLGT CHC POPS WITH
EACH WAVE...BUT WITH LESS THAN FAVORABLE TRACK FOR THE AREA SEE NO
REASON TO MESS UP GRIDS WITH SEVERAL PERIODS OF SLGT CHCS. TEMPS
WILL ATTEMPT TO MODERATE SOMEWHAT AT LEAST BACK TOWARDS NORMAL
THROUGH THE PERIOD.
POINT OF INTEREST...POLAR VORTEX WILL BEGIN ITS SLOW MIGRATION SOUTH
INTO HUDSON BAY THROUGH THE UPCOMING WEEK. WHILE MODELS HAVE BEEN
ADVERTISING ON AND OFF FOR SEVERAL WEEKS OF A ARCTIC INTRUSION
DROPPING INTO THE LAKES THIS HAS LARGELY NOT COME TO FRUITION AS OF
YET. 00Z RUNS OF EURO AND GFS BOTH IN GENERAL AGREEMENT ON LARGE
PIECE OF THIS VORTEX DROPPING SOUTH ENOUGH TO IMPACT THE AREA WITH
-28 C OR COLDER TEMPS DROPPING THROUGH THE WESTERN GREAT LAKES
TOWARDS THE FORECAST AREA. AS ALWAYS...CONFIDENCE IN ANY MODEL 240
HOURS OUT VERY VERY LOW...SOMETHING TO MONITOR TREND WISE OVER THE
NEXT WEEK.
&&
.AVIATION... /06 UTC TAFS/
PRIME FOCUS ON CURRENT/NEXT HAZARDS...LLWS/RAIN RESPECTIVELY. SLIGHT
ADJUSTMENTS TO SLIGHTLY MORE VEERED LLJ PER PRESENT UPSTREAM
VWP/PROFILER DATA AND RAP ANALYSIS. FOCUS FOR RENEWED LIFT IN
WARM/ABNORMALLY MOIST ENVIRONMENT COMMENCES LATE TONIGHT AND HAVE
INTRODUCED DOWNWARD TREND. SUSPECT HIR PROB FOR MORE WIDESPREAD IFR
MET CONDS TO BE REALIZED WITH TIME/BY 12 UTC SUN ACRS NRN IN...AND
TO BE ASSESSED IN LATER FCSTS.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST MONDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MURPHY
LONG TERM...FISHER
AVIATION...MURPHY
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
643 AM EST SAT JAN 12 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EST SAT JAN 12 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
NW ONTARIO INTO THE SW CONUS AND A RIDGE OVER THE EAST RESULTING IN
SW FLOW FROM THE SRN PLAINS INTO THE WRN GREAT LAKES. A SHEARED
SHORTWAVE TROUGH WAS LIFTING NORTHEAST THROUGH NRN MN. AT THE
SFC...A 993 MB LOW WAS LOCATED OVER THE MN ARROWHEAD WITH A COLD
FRONT EXTENDING TO THE SSE THROUGH NW INTO CNTRL WI. VERY MILD SSW
FLOW AHEAD OF THE FRONT HAS PUSHED TEMPS INTO THE LOWER 40S ACROSS
MOST OF UPPER MI. GUSTY SW WINDS HAVE DEVELOPED BEHIND THE COLD
FRONT AS A 5MB/3HR PRES RISE MAX TRAILS THE FRONT OVER SRN MN.
RADARS INDICATED AREAS OF LIGHT PCPN OVER ERN MN INTO NW WI WITH NO
RETURNS TO THE EAST.
MAIN FCST CONCERNS ARE WINDS AND LAKE EFFECT SNOW POTENTIAL.
TODAY...MODELS HAVE BEEN CONSISTENT WITH THE LOW QUICKLY LIFTING
NORTHEAST TO JAMES BAY BY LATE TODAY. THIS WILL DRAG THE COLD FRONT
THROUGH THE CWA BY 18Z BRINGING THE STRONGEST ISALLOBARIC GRADIENT
THROUGH THE WEST HALF OF UPPER MICHIGAN THIS MORNING. WITH STRONG
CAA AND INCREASE IN MIXED LAYER DEPTH...GUSTY WINDS IN THE 25 TO 35
MPH RANGE ARE EXPECTED OVER MOST OF THE REGION. SINCE THE SW WINDS
ARE MAINLY PARALLEL TO THE KEWEENAW PENINSULA THE STRONGER GUSTS ARE
EXPECTED DURING THE AFTERNOON AS WINDS VEER MORE TO THE WSW. THIS
WOULD BRING THE STRONGEST GUSTS MAINLY ACROSS THE WESTERN SHORE OF
THE KEWEENAW. A WIND ADVISORY IS IN EFFECT WHICH HIGHLIGHTS THESE
LOCATIONS. BY THE TIME THAT WINDS VEER TO THE WEST WHICH WOULD FAVOR
LOCATIONS IN THE HIGHER TERRAIN AROUND CMX...THE GRADIENT WEAKENS.
LAKE INDUCED CAPE VALUES CLIMB QUICKLY TO AROUND 300-400 J/KG BY
LATE AFTERNOON AS 850 MB TEMPS FALL TO NEAR -15C. THE STRONGEST LOW
LEVEL CONVERGENCE AND GREATEST LES IS EXPECTED TO FOCUS TOWARD THE
NRN PORTION OF THE KEWEENAW....FROM CMX NORTHWARD.
TONIGHT...INSTABILITY OVER THE LAKE WILL INCREASE AS 850 MB TEMPS
DROP TO AROUND -18C. THE HIGHER RES MODELS SUGGEST THAT EVEN AS THE
WINDS OVER WRN LAKE SUPERIOR VEER MORE TO THE NW...LAKE INDUCED
TROUGHING WILL KEEP THE CONVERGENT WINDS OVER THE KEWEENAW. EVEN
THOUGH INVERSION HEIGHTS ARE ONLY FCST NEAR 4K FT...WITH THE
MOISTURE DEPTH TO AT LEAST 7K FT...AT LEAST MODERATE INTENSITY LES
IS EXPECTED THAT COULD BRING 2 TO 4 INCHES TO LOCATIONS FROM NE
ONTONAGON COUNTY THROUGH THE HIGHER TERRAIN OF THE KEWEENAW
PENINSULA. A LES ADVISORY WAS POSTED WHICH EXTENDS THROUGH SUNDAY
NIGHT(DETAILS IN SUBSEQUENT DISCUSSION).
A SHORTWAVE MOVING TOWARD THE GREAT LAKE FROM THE CNTRL PLAINS ALONG
WITH UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF THE 170 KT 300 MB
JET INTO NRN ONTARIO WILL ALSO SUPPORT AN AREA OF LIGHT SNOW THAT
WILL GRAZE THE SE PORTIONS OF THE CWA. SINCE THE HEAVIER PCPN IS
EXPECTED TO THE SOUTH...ACCUMULATIONS ARE EXPECTED TO REMAIN BELOW
AN INCH.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 534 AM EST SAT JAN 12 2013
AREA WILL BE ENTERING BACK INTO A MORE WINTER TIME PATTERN
TODAY...WHICH WILL CONTINUE THROUGH THE LONG TERM PERIOD.
SYSTEM MOVING THROUGH THE LOWER GREAT LAKES TONIGHT INTO SUNDAY HAS
HAS SHIFTED A LITTLE MORE TO THE NORTHWEST OVER THE LAST FEW RUNS
AND NOW BRUSHES THE COUNTIES NEAR LAKE MICHIGAN WITH SOME LIGHT SNOW
SUNDAY MORNING. THIS NORTHWEST SHIFT HAS CAUSES THE DEEPER MOISTURE
WITH A LEFT OVER SHORTWAVE FROM THE LOW CURRENTLY IN MN TO REMAIN
JUST TO THE WEST OF LAKE SUPERIOR ON SUNDAY MORNING AND THE FIRST
PART OF THE AFTERNOON. THIS LEADS TO SOME CONCERN FOR THE INITIAL
LAKE EFFECT FROM LINGERING SURFACE TROUGH OVER SOUTHERN LAKE
SUPERIOR. SINCE THE COLD AIR SURGE EXPECTED TODAY INTO TONIGHT WILL
BE FAIRLY SHALLOW...IT WILL SETUP A VERY STRONG INVERSION TONIGHT
AROUND H800 OR 5KFT. THUS...DO EXPECT LAKE EFFECT TO BE OCCURRING
OVER THE WEST-NORTHWEST FAVORED LOCATIONS IN THE WESTERN U.P.
BUT HAVE SOME CONCERNS ON STRENGTH TO START THE PERIOD. ON THE
POSITIVE SIDE...THE BEST FORCING WILL BE FOCUSED IN THE DGZ...BUT
THERE IS SOME SHEAR IN THE CLOUD LAYER...SFC-H925 WINDS OUT OF THE
NORTHWEST AND H850 WINDS OUT OF THE WEST IN THE MORNING AND THEN
SOUTHWEST IN THE AFTERNOON. WONDERING IF THIS WILL KEEP THE FOCUS
AWAY FROM A DOMINATE BAND IN MORE GENERAL MULTIBAND LAKE EFFECT.
LAKE EFFECT SNOW PARAMETER...WHICH HAS DONE A GOOD JOB HIGHLIGHTING
THE FEW LAKE EFFECT EVENTS WE HAVE HAD THIS SEASON...KEEPS VALUES
LIMITED DURING THE MORNING HOURS AND WILL KEEP SNOWFALL AMOUNTS
LIGHTER.
ONCE THE SURFACE LOW SLIDES NORTHEAST INTO WESTERN QUEBEC SUNDAY
AFTERNOON AND EVENING...THEN THE SURFACE TROUGH WILL SLIDE SOUTH
SLIGHTLY LEADING TO LESS SHEAR AND RISING INVERSION HEIGHTS TO
6-7KFT DUE TO DEEPER MOISTURE IN MN BEING DRAGGED THROUGH THE
WESTERN CWA. LAKE EFFECT SNOW PARAMETER PEAKS TO 2 IN THIS
PERIOD...SO EXPECT INTENSITY OF THE LAKE EFFECT TO FOLLOW SUIT. AT
THIS POINT...THINK IT WILL BE IN NORTHWEST FAVORED LOCATIONS
ALTHOUGH HIGHER RESOLUTION MODELS ARE TRYING TO HINT AT ENHANCED
CONVERGENCE IN THE HOUGHTON/ONTONAGON/GOGEBIC COUNTY AREA. CHECKLIST
GIVES 3-5IN PER 12HRS FOR SUNDAY AND SUNDAY NIGHT AND THAT SEEMS TO
FIT WELL WITH THE GOING FORECAST...AS SNOW RATIOS WILL BE IN THE
20-30 TO 1 RANGE. WITH TOTAL SNOW FROM TONIGHT THROUGH SUNDAY NIGHT
OF 7 TO LOCALLY 14 INCHES...WILL ISSUE AN ADVISORY FOR KEWEENAW
THROUGH ONTONAGON COUNTIES. WILL NEED TO WATCH GOGEBIC COUNTY NEAR
THE PORCUPINE MOUNTAINS...AS ARE HINTS OF ENHANCED CONVERGENCE FOR
HIGHER SNOWFALL AMOUNTS THERE.
FARTHER EAST...WITH THE LIGHT SYNOPTIC SNOW LEAVING EARLY SUNDAY
AFTERNOON...TRANSITION WILL OCCUR TO LAKE EFFECT IN THE NORTHWEST
WIND BELTS IN THE AFTERNOON...AS THE SURFACE TROUGH SHIFTS WINDS.
THERE TOO...AMOUNTS WILL BE LIGHT TO MODERATE ON SUNDAY AFTERNOON
INTO THE EVENING...BUT COULD PEAK UP SOME AFTER MIDNIGHT WHEN THE
INVERSION HEIGHTS RISE. MAY NEED AN ADVISORY ON FUTURE SHIFTS FOR
THE SUN AFTERNOON/NIGHT PERIOD.
SURFACE TROUGH THEN SHIFTS NORTH ON MONDAY...PUSHING THE SNOW
OFFSHORE OVER THE EAST AND FOCUSES IT OVER THE KEWEENAW IN THE
WEST. INTENSITY SHOULD WEAKEN SOME AS THE DEEPER MOISTURE DEPARTS
AND INVERSION HEIGHTS DROP TO 5-6KFT. WITH THE CLOUD FOCUSED IN THE
DGZ...STILL SHOULD SEE GOOD SNOW RATIOS AND LIGHT SNOWFALL
ACCUMULATIONS IN THE 1-3 INCH RANGE FOR THE KEWEENAW.
SURFACE LOW DEVELOPS OVER EASTERN LAKE SUPERIOR MONDAY NIGHT AND
ENHANCES A SURFACE TROUGH OVER THE CENTRAL AND WESTERN PORTIONS OF
LAKE. MEANWHILE...DEEPER MOISTURE SLIDES THROUGH ASSOCIATED WITH A
SHORTWAVE MOVING THROUGH THE NORTHERN STREAM NORTHWEST FLOW. THERE
WILL LIKELY BE A STRONGER...DOMINATE LES BAND ASSOCIATED WITH THIS
TROUGH...BUT MODELS VARY ON THE EXACT LOCATION. AREA NEAR THE TIP OF
THE KEWEENAW WILL HAVE THE BEST CHANCE FOR SEEING THIS BAND LATE
MONDAY NIGHT INTO TUESDAY...SO WILL HIGHLIGHT HIGHER POPS/SNOWFALL
THERE. LES SHOULD DIMINISH TUESDAY AFTERNOON...AS WEAK RIDGING ALOFT
PRODUCES DRIER AIR AND WAA AHEAD OF THE NEXT SHORTWAVE.
THE NEXT SHORTWAVE AND ASSOCIATED CLIPPER LOW WILL MOVE ACROSS THE
CWA ON WEDNESDAY INTO WEDNESDAY EVENING. AS IS NORMALLY THE
CASE...THE GFS IS ON THE FAST SIDE AND THE ECMWF/GEM ARE ABOUT
6-12HRS BEHIND. WILL FOLLOW THAT IDEA FOR POPS AND THINK MOST AREAS
WILL SEE A DUSTING TO AN INCH OF SYNOPTIC SNOW.
POLAR VORTEX IS EXPECTED TO DROP SOUTH RIGHT BEHIND THIS WAVE AND
LEAD TO SOME OF THE COLDEST TEMPERATURES OF THE WINTER SEASON FOR
UPPER MICHIGAN. MODELS HAVE BEEN STRUGGLING WITH THIS PERIOD...DUE
TO THE PHASING OF THE NORTHERN/SOUTHERN STREAMS OF THE UPPER JET IN
THE EASTERN CONUS ON THURSDAY...BUT THE GENERAL IDEA OF COLD
WEATHER IS THERE. THE HPC PREFERRED BLEND OF ECMWF/ECENS MEAN SEEMS
TO BE THE WAY TO GO WITH THE GFS JUMPING 15C AT H850 FROM RUN TO
RUN. THIS COLD AIR...H850 TEMPS ON THE ECMWF IN THE MID -20S WILL
EASILY LEAD TO LAKE EFFECT SNOW IN THE NORTHWEST WIND LOCATIONS.
DELTA-T VALUES SHOULD BE FAIRLY IMPRESSIVE...IN THE UPPER 20S BUT
THE COLD AIR WILL PUSH THE DGZ TOWARDS THE SURFACE AND PRODUCE A
LESS FLUFFY /PLATES OR COLUMNS/ SNOW. WILL KEEP THE SAME IDEA AS
THE PREVIOUS SHIFT OF HIGH END LIKELY POPS FOR WEDNESDAY NIGHT INTO
FRIDAY FOR NORTHWEST AND EVENTUALLY WEST-NORTHWEST FAVORED
LOCATIONS. ONE FINAL ITEM TO NOTE DURING THIS PERIOD IS THE 00Z
GEM/GFS ARE BOTH SHOWING A CLIPPER MOVING THROUGH THE UPPER
MISSISSIPPI VALLEY ON THURSDAY INTO THURSDAY NIGHT...WHILE
THE ECMWF IS ABOUT A DAY LATER AND MAY BRUSH THE CWA.
HIGHS FOR THE PERIOD WILL BE IN THE TEENS TO MIDDLE 20S...WITH THE
COLDEST HIGHS EXPECTED ON THURSDAY/FRIDAY. LOWS WILL ALSO BE NEAR
NORMAL...WITH VALUES IN THE SINGLE DIGITS TO MIDDLE TEENS ABOVE
ZERO.
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)
ISSUED AT 641 AM EST SAT JAN 12 2013
CONDITIONS AT SAW SHOULD QUICKLY IMPROVE INTO THE MVFR RANGE THIS
MORNING AT SAW AS WINDS VEER FROM THE S TO A MORE DOWNSLOPE SW
DIRECTION. A STRONG COLD FRONT WILL PUSH THROUGH THE AREA THIS
MORNING BRINGING GUSTY SOUTHWEST WINDS. THE STRONGEST GUSTS WILL
BE AT OROGRAPHICALLY FAVORED CMX WHERE GUSTS COULD REACH 40KTS. AS
TEMPERATURES FALL THROUGH THE DAY...LAKE EFFECT -SHSN SHOULD AFFECT
CMX WITH ANY LIGHT ACCUMULATIONS RESULTING IN BLSN BEFORE WINDS
BEGIN TO DIMINISH TOWARDS EVENING. LAKE EFFECT SNOW WITH PREDOMINANT
IFR VSBY IS EXPECTED TO CONTINUE THROUGH TONIGHT. AT IWD/SAW MAINLY
MVFR CONDITIONS SHOULD PREVAIL THROUGH THE FCST PERIOD.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EST SAT JAN 12 2013
LOW PRESSURE ACROSS NE MN WILL MOVE NORTHEAST TO JAMES BAY LATE TODAY
BRINGING GALES ACROSS LAKE SUPERIOR. STRONG SW GALES OF 35 WILL
DEVELOP TOWARD DAYBREAK ACROSS THE WESTERN LAKE BEHIND THE COLD FRONT
AND INCREASE TO 40-45KTS. EXPECT THE GALES TO DIMINISH AS THE
STRONGEST WINDS SLOWLY EDGE SE...AS WINDS BEGIN TO TURN W BY LATE
AFTERNOON.
A TROUGH AVERAGING WILL LINGER ACROSS LAKE SUPERIOR THROUGH
SUNDAY...BEFORE SLOWLY WEAKENING AS STRONGER 30.4 INCH HIGH PRESSURE
EXPANDS ACROSS CENTRAL CANADA THROUGH THE CENTRAL PLAINS STATES
THROUGH MONDAY. NW WINDS COULD AGAIN GUST TO NEAR 30KTS OVER SE LS
SUNDAY NIGHT. LOW PRESSURE OVER MANITOBA AND ND TUESDAY NIGHT WILL
LIKELY PUSH ACROSS ONTARIO AND THE UPPER GREAT LAKES ON WEDNESDAY.
ANOTHER PERIOD OF SW-W 30-35KTS WINDS WILL BE POSSIBLE TUESDAY
AFTERNOON INTO THE EVENING HOURS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST
MONDAY FOR MIZ001-003.
WIND ADVISORY FROM NOON TODAY TO 8 PM EST THIS EVENING FOR
MIZ001-003.
LAKE EFFECT SNOW ADVISORY FROM 10 PM THIS EVENING TO 7 AM EST
MONDAY FOR MIZ002.
LAKE SUPERIOR...
GALE WARNING FROM 10 AM EST /9 AM CST/ THIS MORNING TO 10 PM EST
/9 PM CST/ THIS EVENING FOR LSZ240>246-265>267.
GALE WARNING UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR LSZ162-
263-264.
LAKE MICHIGAN...
DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR LMZ221-248-
250.
GALE WARNING FROM 11 AM THIS MORNING TO 9 PM EST THIS EVENING
FOR LMZ221-248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...JLB
MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
535 AM EST SAT JAN 12 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EST SAT JAN 12 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
NW ONTARIO INTO THE SW CONUS AND A RIDGE OVER THE EAST RESULTING IN
SW FLOW FROM THE SRN PLAINS INTO THE WRN GREAT LAKES. A SHEARED
SHORTWAVE TROUGH WAS LIFTING NORTHEAST THROUGH NRN MN. AT THE
SFC...A 993 MB LOW WAS LOCATED OVER THE MN ARROWHEAD WITH A COLD
FRONT EXTENDING TO THE SSE THROUGH NW INTO CNTRL WI. VERY MILD SSW
FLOW AHEAD OF THE FRONT HAS PUSHED TEMPS INTO THE LOWER 40S ACROSS
MOST OF UPPER MI. GUSTY SW WINDS HAVE DEVELOPED BEHIND THE COLD
FRONT AS A 5MB/3HR PRES RISE MAX TRAILS THE FRONT OVER SRN MN.
RADARS INDICATED AREAS OF LIGHT PCPN OVER ERN MN INTO NW WI WITH NO
RETURNS TO THE EAST.
MAIN FCST CONCERNS ARE WINDS AND LAKE EFFECT SNOW POTENTIAL.
TODAY...MODELS HAVE BEEN CONSISTENT WITH THE LOW QUICKLY LIFTING
NORTHEAST TO JAMES BAY BY LATE TODAY. THIS WILL DRAG THE COLD FRONT
THROUGH THE CWA BY 18Z BRINGING THE STRONGEST ISALLOBARIC GRADIENT
THROUGH THE WEST HALF OF UPPER MICHIGAN THIS MORNING. WITH STRONG
CAA AND INCREASE IN MIXED LAYER DEPTH...GUSTY WINDS IN THE 25 TO 35
MPH RANGE ARE EXPECTED OVER MOST OF THE REGION. SINCE THE SW WINDS
ARE MAINLY PARALLEL TO THE KEWEENAW PENINSULA THE STRONGER GUSTS ARE
EXPECTED DURING THE AFTERNOON AS WINDS VEER MORE TO THE WSW. THIS
WOULD BRING THE STRONGEST GUSTS MAINLY ACROSS THE WESTERN SHORE OF
THE KEWEENAW. A WIND ADVISORY IS IN EFFECT WHICH HIGHLIGHTS THESE
LOCATIONS. BY THE TIME THAT WINDS VEER TO THE WEST WHICH WOULD FAVOR
LOCATIONS IN THE HIGHER TERRAIN AROUND CMX...THE GRADIENT WEAKENS.
LAKE INDUCED CAPE VALUES CLIMB QUICKLY TO AROUND 300-400 J/KG BY
LATE AFTERNOON AS 850 MB TEMPS FALL TO NEAR -15C. THE STRONGEST LOW
LEVEL CONVERGENCE AND GREATEST LES IS EXPECTED TO FOCUS TOWARD THE
NRN PORTION OF THE KEWEENAW....FROM CMX NORTHWARD.
TONIGHT...INSTABILITY OVER THE LAKE WILL INCREASE AS 850 MB TEMPS
DROP TO AROUND -18C. THE HIGHER RES MODELS SUGGEST THAT EVEN AS THE
WINDS OVER WRN LAKE SUPERIOR VEER MORE TO THE NW...LAKE INDUCED
TROUGHING WILL KEEP THE CONVERGENT WINDS OVER THE KEWEENAW. EVEN
THOUGH INVERSION HEIGHTS ARE ONLY FCST NEAR 4K FT...WITH THE
MOISTURE DEPTH TO AT LEAST 7K FT...AT LEAST MODERATE INTENSITY LES
IS EXPECTED THAT COULD BRING 2 TO 4 INCHES TO LOCATIONS FROM NE
ONTONAGON COUNTY THROUGH THE HIGHER TERRAIN OF THE KEWEENAW
PENINSULA. A LES ADVISORY WAS POSTED WHICH EXTENDS THROUGH SUNDAY
NIGHT(DETAILS IN SUBSEQUENT DISCUSSION).
A SHORTWAVE MOVING TOWARD THE GREAT LAKE FROM THE CNTRL PLAINS ALONG
WITH UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF THE 170 KT 300 MB
JET INTO NRN ONTARIO WILL ALSO SUPPORT AN AREA OF LIGHT SNOW THAT
WILL GRAZE THE SE PORTIONS OF THE CWA. SINCE THE HEAVIER PCPN IS
EXPECTED TO THE SOUTH...ACCUMULATIONS ARE EXPECTED TO REMAIN BELOW
AN INCH.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 534 AM EST SAT JAN 12 2013
AREA WILL BE ENTERING BACK INTO A MORE WINTER TIME PATTERN
TODAY...WHICH WILL CONTINUE THROUGH THE LONG TERM PERIOD.
SYSTEM MOVING THROUGH THE LOWER GREAT LAKES TONIGHT INTO SUNDAY HAS
HAS SHIFTED A LITTLE MORE TO THE NORTHWEST OVER THE LAST FEW RUNS
AND NOW BRUSHES THE COUNTIES NEAR LAKE MICHIGAN WITH SOME LIGHT SNOW
SUNDAY MORNING. THIS NORTHWEST SHIFT HAS CAUSES THE DEEPER MOISTURE
WITH A LEFT OVER SHORTWAVE FROM THE LOW CURRENTLY IN MN TO REMAIN
JUST TO THE WEST OF LAKE SUPERIOR ON SUNDAY MORNING AND THE FIRST
PART OF THE AFTERNOON. THIS LEADS TO SOME CONCERN FOR THE INITIAL
LAKE EFFECT FROM LINGERING SURFACE TROUGH OVER SOUTHERN LAKE
SUPERIOR. SINCE THE COLD AIR SURGE EXPECTED TODAY INTO TONIGHT WILL
BE FAIRLY SHALLOW...IT WILL SETUP A VERY STRONG INVERSION TONIGHT
AROUND H800 OR 5KFT. THUS...DO EXPECT LAKE EFFECT TO BE OCCURRING
OVER THE WEST-NORTHWEST FAVORED LOCATIONS IN THE WESTERN U.P.
BUT HAVE SOME CONCERNS ON STRENGTH TO START THE PERIOD. ON THE
POSITIVE SIDE...THE BEST FORCING WILL BE FOCUSED IN THE DGZ...BUT
THERE IS SOME SHEAR IN THE CLOUD LAYER...SFC-H925 WINDS OUT OF THE
NORTHWEST AND H850 WINDS OUT OF THE WEST IN THE MORNING AND THEN
SOUTHWEST IN THE AFTERNOON. WONDERING IF THIS WILL KEEP THE FOCUS
AWAY FROM A DOMINATE BAND IN MORE GENERAL MULTIBAND LAKE EFFECT.
LAKE EFFECT SNOW PARAMETER...WHICH HAS DONE A GOOD JOB HIGHLIGHTING
THE FEW LAKE EFFECT EVENTS WE HAVE HAD THIS SEASON...KEEPS VALUES
LIMITED DURING THE MORNING HOURS AND WILL KEEP SNOWFALL AMOUNTS
LIGHTER.
ONCE THE SURFACE LOW SLIDES NORTHEAST INTO WESTERN QUEBEC SUNDAY
AFTERNOON AND EVENING...THEN THE SURFACE TROUGH WILL SLIDE SOUTH
SLIGHTLY LEADING TO LESS SHEAR AND RISING INVERSION HEIGHTS TO
6-7KFT DUE TO DEEPER MOISTURE IN MN BEING DRAGGED THROUGH THE
WESTERN CWA. LAKE EFFECT SNOW PARAMETER PEAKS TO 2 IN THIS
PERIOD...SO EXPECT INTENSITY OF THE LAKE EFFECT TO FOLLOW SUIT. AT
THIS POINT...THINK IT WILL BE IN NORTHWEST FAVORED LOCATIONS
ALTHOUGH HIGHER RESOLUTION MODELS ARE TRYING TO HINT AT ENHANCED
CONVERGENCE IN THE HOUGHTON/ONTONAGON/GOGEBIC COUNTY AREA. CHECKLIST
GIVES 3-5IN PER 12HRS FOR SUNDAY AND SUNDAY NIGHT AND THAT SEEMS TO
FIT WELL WITH THE GOING FORECAST...AS SNOW RATIOS WILL BE IN THE
20-30 TO 1 RANGE. WITH TOTAL SNOW FROM TONIGHT THROUGH SUNDAY NIGHT
OF 7 TO LOCALLY 14 INCHES...WILL ISSUE AN ADVISORY FOR KEWEENAW
THROUGH ONTONAGON COUNTIES. WILL NEED TO WATCH GOGEBIC COUNTY NEAR
THE PORCUPINE MOUNTAINS...AS ARE HINTS OF ENHANCED CONVERGENCE FOR
HIGHER SNOWFALL AMOUNTS THERE.
FARTHER EAST...WITH THE LIGHT SYNOPTIC SNOW LEAVING EARLY SUNDAY
AFTERNOON...TRANSITION WILL OCCUR TO LAKE EFFECT IN THE NORTHWEST
WIND BELTS IN THE AFTERNOON...AS THE SURFACE TROUGH SHIFTS WINDS.
THERE TOO...AMOUNTS WILL BE LIGHT TO MODERATE ON SUNDAY AFTERNOON
INTO THE EVENING...BUT COULD PEAK UP SOME AFTER MIDNIGHT WHEN THE
INVERSION HEIGHTS RISE. MAY NEED AN ADVISORY ON FUTURE SHIFTS FOR
THE SUN AFTERNOON/NIGHT PERIOD.
SURFACE TROUGH THEN SHIFTS NORTH ON MONDAY...PUSHING THE SNOW
OFFSHORE OVER THE EAST AND FOCUSES IT OVER THE KEWEENAW IN THE
WEST. INTENSITY SHOULD WEAKEN SOME AS THE DEEPER MOISTURE DEPARTS
AND INVERSION HEIGHTS DROP TO 5-6KFT. WITH THE CLOUD FOCUSED IN THE
DGZ...STILL SHOULD SEE GOOD SNOW RATIOS AND LIGHT SNOWFALL
ACCUMULATIONS IN THE 1-3 INCH RANGE FOR THE KEWEENAW.
SURFACE LOW DEVELOPS OVER EASTERN LAKE SUPERIOR MONDAY NIGHT AND
ENHANCES A SURFACE TROUGH OVER THE CENTRAL AND WESTERN PORTIONS OF
LAKE. MEANWHILE...DEEPER MOISTURE SLIDES THROUGH ASSOCIATED WITH A
SHORTWAVE MOVING THROUGH THE NORTHERN STREAM NORTHWEST FLOW. THERE
WILL LIKELY BE A STRONGER...DOMINATE LES BAND ASSOCIATED WITH THIS
TROUGH...BUT MODELS VARY ON THE EXACT LOCATION. AREA NEAR THE TIP OF
THE KEWEENAW WILL HAVE THE BEST CHANCE FOR SEEING THIS BAND LATE
MONDAY NIGHT INTO TUESDAY...SO WILL HIGHLIGHT HIGHER POPS/SNOWFALL
THERE. LES SHOULD DIMINISH TUESDAY AFTERNOON...AS WEAK RIDGING ALOFT
PRODUCES DRIER AIR AND WAA AHEAD OF THE NEXT SHORTWAVE.
THE NEXT SHORTWAVE AND ASSOCIATED CLIPPER LOW WILL MOVE ACROSS THE
CWA ON WEDNESDAY INTO WEDNESDAY EVENING. AS IS NORMALLY THE
CASE...THE GFS IS ON THE FAST SIDE AND THE ECMWF/GEM ARE ABOUT
6-12HRS BEHIND. WILL FOLLOW THAT IDEA FOR POPS AND THINK MOST AREAS
WILL SEE A DUSTING TO AN INCH OF SYNOPTIC SNOW.
POLAR VORTEX IS EXPECTED TO DROP SOUTH RIGHT BEHIND THIS WAVE AND
LEAD TO SOME OF THE COLDEST TEMPERATURES OF THE WINTER SEASON FOR
UPPER MICHIGAN. MODELS HAVE BEEN STRUGGLING WITH THIS PERIOD...DUE
TO THE PHASING OF THE NORTHERN/SOUTHERN STREAMS OF THE UPPER JET IN
THE EASTERN CONUS ON THURSDAY...BUT THE GENERAL IDEA OF COLD
WEATHER IS THERE. THE HPC PREFERRED BLEND OF ECMWF/ECENS MEAN SEEMS
TO BE THE WAY TO GO WITH THE GFS JUMPING 15C AT H850 FROM RUN TO
RUN. THIS COLD AIR...H850 TEMPS ON THE ECMWF IN THE MID -20S WILL
EASILY LEAD TO LAKE EFFECT SNOW IN THE NORTHWEST WIND LOCATIONS.
DELTA-T VALUES SHOULD BE FAIRLY IMPRESSIVE...IN THE UPPER 20S BUT
THE COLD AIR WILL PUSH THE DGZ TOWARDS THE SURFACE AND PRODUCE A
LESS FLUFFY /PLATES OR COLUMNS/ SNOW. WILL KEEP THE SAME IDEA AS
THE PREVIOUS SHIFT OF HIGH END LIKELY POPS FOR WEDNESDAY NIGHT INTO
FRIDAY FOR NORTHWEST AND EVENTUALLY WEST-NORTHWEST FAVORED
LOCATIONS. ONE FINAL ITEM TO NOTE DURING THIS PERIOD IS THE 00Z
GEM/GFS ARE BOTH SHOWING A CLIPPER MOVING THROUGH THE UPPER
MISSISSIPPI VALLEY ON THURSDAY INTO THURSDAY NIGHT...WHILE
THE ECMWF IS ABOUT A DAY LATER AND MAY BRUSH THE CWA.
HIGHS FOR THE PERIOD WILL BE IN THE TEENS TO MIDDLE 20S...WITH THE
COLDEST HIGHS EXPECTED ON THURSDAY/FRIDAY. LOWS WILL ALSO BE NEAR
NORMAL...WITH VALUES IN THE SINGLE DIGITS TO MIDDLE TEENS ABOVE
ZERO.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY MORNING)
ISSUED AT 534 AM EST SAT JAN 12 2013
AS SOUTHERLY WINDS INCREASE OVERNIGHT VISIBILITIES SHOULD SLOWLY
IMPROVE AT CMX AND SAW. HOWEVER...CIGS WILL GENERALLY REMAIN IN THE
LIFR RANGE. CONDITIONS SHOULD IMPROVE INTO THE MVFR RANGE ON
SATURDAY BEHIND A STRONG COLD FRONT PUSHING THROUGH THE AREA. STRONG
PRESSURE RISES AND A TIGHT PRESSURE GRADIENT WILL RESULT IN GUSTY
WEST TO SOUTHWEST WINDS DURING THE DAY. THE STRONGEST GUSTS WILL BE
AT OROGRAPHICALLY FAVORED CMX WHERE GUSTS COULD TOP 40KTS. AS
TEMPERATURES FALL THROUGH THE DAY LAKE EFFECT -SHSN SHOULD AFFECT
CMX WITH ANY LIGHT ACCUMULATIONS RESULTING IN BLSN BEFORE WINDS
BEGIN TO DIMINISH TOWARDS EVENING.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EST SAT JAN 12 2013
LOW PRESSURE ACROSS NE MN WILL MOVE NORTHEAST TO JAMES BAY LATE TODAY
BRINGING GALES ACROSS LAKE SUPERIOR. STRONG SW GALES OF 35 WILL
DEVELOP TOWARD DAYBREAK ACROSS THE WESTERN LAKE BEHIND THE COLD FRONT
AND INCREASE TO 40-45KTS. EXPECT THE GALES TO DIMINISH AS THE
STRONGEST WINDS SLOWLY EDGE SE...AS WINDS BEGIN TO TURN W BY LATE
AFTERNOON.
A TROUGH AVERAGING WILL LINGER ACROSS LAKE SUPERIOR THROUGH
SUNDAY...BEFORE SLOWLY WEAKENING AS STRONGER 30.4 INCH HIGH PRESSURE
EXPANDS ACROSS CENTRAL CANADA THROUGH THE CENTRAL PLAINS STATES
THROUGH MONDAY. NW WINDS COULD AGAIN GUST TO NEAR 30KTS OVER SE LS
SUNDAY NIGHT. LOW PRESSURE OVER MANITOBA AND ND TUESDAY NIGHT WILL
LIKELY PUSH ACROSS ONTARIO AND THE UPPER GREAT LAKES ON WEDNESDAY.
ANOTHER PERIOD OF SW-W 30-35KTS WINDS WILL BE POSSIBLE TUESDAY
AFTERNOON INTO THE EVENING HOURS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST
MONDAY FOR MIZ001-003.
WIND ADVISORY FROM NOON TODAY TO 8 PM EST THIS EVENING FOR
MIZ001-003.
LAKE EFFECT SNOW ADVISORY FROM 10 PM THIS EVENING TO 7 AM EST
MONDAY FOR MIZ002.
LAKE SUPERIOR...
GALE WARNING FROM 10 AM EST /9 AM CST/ THIS MORNING TO 10 PM EST
/9 PM CST/ THIS EVENING FOR LSZ240>246-265>267.
GALE WARNING UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR LSZ162-
263-264.
LAKE MICHIGAN...
DENSE FOG ADVISORY UNTIL 7 AM EST THIS MORNING FOR LMZ221-248-
250.
GALE WARNING FROM 11 AM THIS MORNING TO 9 PM EST THIS EVENING
FOR LMZ221-248-250.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...MZ
MARINE...JLB
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
744 AM MST SAT JAN 12 2013
.UPDATE...ARCTIC AIRMASS IN PLACE ACROSS THE REGION...WITH A DEEP
NEAR SATURATED ISOTHERMAL OVERHEAD PER THE 12Z RAP SOUNDING.
FORECAST MODELS CONTINUE TO PROG LINGERING LARGE SCALE LIFT OVER
THE FA THROUGH THE DAY IN Q-VECTOR ANALYSIS. GIVEN THE DEEP NEAR
SATURATED PROFILES EXPECTED TO REMAIN IN PLACE THROUGH EARLY TO
MID AFTERNOON...HAVE UPDATED THE FORECAST TO MENTION LIGHT SNOW
LIKELY IN THE MORNING...TRENDING TO CHANCE IN THE AFTERNOON FOR
MOST OF THE FA. GIVEN COLD PROFILES OUTSIDE THE DGZ...SMALL CRYSTAL
PRODUCTION FAVORED...SUGGESTING COLUMNS/SMALL PLATES OR VERY LIGHT
SNOWFALL. ALL ELSE IN GOOD SHAPE.
&&
.AVIATION...12Z TAFS
AREAS OF -SN AND BLSN WILL CONT TO BRING AREAS OF IFR VIS THRU EARLY
THIS MORN. CONDITIONS WILL IMPROVE THRU THE DAY AS WINDS/SNOW
DIMINISH WITH MOST LOCATIONS EXPECTED TO BE VFR BY SUNSET.
&&
.PREV DISCUSSION... /ISSUED 327 AM MST SAT JAN 12 2013/
DISCUSSION...WATER VAPOR SHOWS ELONGATED TROF EXTENDING FROM THE
CA BAJA THROUGH THE NRN PLAINS. AT THE SURFACE...TIGHT PRES GRADS
CONTINUE TO PRODUCE GUSTY NW WINDS ACRS THE CWFA. MAIN LOW CENTER
HAS SHIFTED INTO THE UPPER MIDWEST...ALTHOUGH DEFORMATION ZONE
ACROSS WRN SD CONTINUES TO PRODUCE LIGHT SNOW ACROSS OUR AREA.
WIND CHILLS HAVE DROPPED TO 15 BELOW TO 30 BELOW ZERO.
TODAY...WEAK LIFT WILL CONTINUE TO PRODUCE SOME LIGHT SNOW ACROSS
THE CWFA THIS MORNING ALTHOUGH ANY ADDITIONAL ACCUMULATIONS WILL
REMAIN LESS THAN AN INCH. HOWEVER...WINDS GUSTING TO AROUND 40 MPH
WILL CONTINUE TO PRODUCE AREAS OF BLOWING SNOW ESPECIALLY ON THE
SD PLAINS THIS MORNING...ALONG WITH WIND CHILLS TO 30 BELOW. HAVE
DOWNGRADED THE WINTER STORM WARNING OVER PORTIONS OF WRN SD GIVEN
THE DIMINISHING SNOW...AND WILL CARRY WINTER WX ADVISORIES FOR THE
ENTIRE CWFA THROUGH THE MORNING GIVEN COMBINATION OF BLOWING SNOW
AND WIND CHILLS. CONDITIONS WILL IMPROVE THIS AFTERNOON AS WINDS
RELAX.
TONIGHT THROUGH MONDAY NIGHT...UPPER TROF AXIS WILL SHIFT ONLY
SLIGHTLY EWD INTO EARLY NEXT WEEK...WITH SURFACE RIDGE DOMINATE
OVER THE NRN PLAINS. THIS WILL LEAD TO ONLY A SLOW RISE IN
TEMPS...WITH SNOW COVERED AREAS REMAINING SEVERAL DEGREES BELOW
GUIDANCE. GENERALLY DRY CONDITIONS EXPECTED...ALTHOUGH A FEW SNOW
SHOWERS POSSIBLE IN THE NRN BLKHLS SUNDAY AS A WEAK SHORT WAVE
CROSSES THE REGION.
EXTENDED...WARM FRONT PUSHES OVER THE REGION TUESDAY...WITH BROAD
AREA OF ISENTROPIC LIFT DEVELOPING MAINLY OVER THE WRN CWA.
THEREFORE...WILL KEEP PRECIP CHANCES OVER THIS AREA THRU THE DAY
WITH CHANCES DIMINISHING OVERNIGHT. SOME PRECIP OVERNIGHT MAY BE
FREEZING RAIN AS WARM AIR ALOFT CONTINUES TO SLIDE IN...SO WILL HAVE
TO KEEP AN EYE ON THIS. FOR THE REMAINDER OF THE WEEK...
WEST/NORTHWEST FLOW ALOFT SETS UP OVER THE AREA BRINGING NEAR
TO SLIGHTLY ABOVE AVERAGE TEMPERATURES AND DRY CONDITIONS.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...WINTER WEATHER ADVISORY UNTIL 11 AM MST /NOON CST/ THIS MORNING
FOR BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL
RIVER-HAAKON-HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-
NORTHERN BLACK HILLS-NORTHERN FOOT HILLS-NORTHERN MEADE CO
PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY-SHANNON-
SOUTHERN BLACK HILLS-SOUTHERN FOOT HILLS-SOUTHERN MEADE CO
PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-ZIEBACH.
WY...WINTER WEATHER ADVISORY UNTIL 11 AM MST THIS MORNING FOR
NORTHEASTERN CROOK-NORTHERN CAMPBELL-SOUTHERN CAMPBELL-
WESTERN CROOK-WESTON-WYOMING BLACK HILLS.
&&
$$
SHORT TERM...JOHNSON
EXTENDED...77
AVIATION...77
UPDATE...JC
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
145 PM EST SAT JAN 12 2013
.SYNOPSIS...
18Z WATER VAPOR AND H4 RAP ANALYSIS SHOW A HIGHLY AMPLIFIED PATTERN
IN PLACE OVER THE CONUS. LUCKILY FOR US...THE WARM AND FAIR WEATHER
SIDE OF THIS AMPLIFICATION RESIDES OVER OUR HEADS...AND WILL
CONTINUE TO DO SO FOR THE REMAINDER OF THE WEEKEND. LARGE SCALE
PATTERN CONSISTS OF DEEP LONGWAVE TROUGHING IN PLACE OVER THE
WESTERN HALF OF THE NATION FOLLOWED DOWNSTREAM BY LONGWAVE RIDGING
EXTENDING FROM THE EASTERN GULF OF MEXICO NORTHWARD ALONG THE ENTIRE
EASTERN SEABOARD. WV IMAGERY CONTINUES TO SHOW AN INTERESTING SPIN /
LEFTOVER MCV PUSHING THROUGH THE RIDGE OFF THE NORTHEAST FL COAST.
THIS VORTICITY CENTER IS LIKELY LEFTOVER FROM CONVECTION TO OUR WEST
DURING THE PAST COUPLE DAYS. THIS FEATURE IS VISUALLY INTERESTING...
BUT WILL HAVE LITTLE IMPACT ON OUR LOCAL WEATHER OTHER THAN SOME
WEAK NVA/ENHANCE SUPPRESSION OVER THE AREA THROUGH THE AFTERNOON.
12Z KTBW SOUNDING PROFILE SHOWS THE INFLUENCE OF THE UPPER RIDGE
WITH A DISTINCT SUBSIDENCE INVERSION ABOVE 850MB. COLUMN IS QUITE
DRY ABOVE THIS LEVEL...BUT SEEING ENOUGH MOISTURE UNDERNEATH TO ONCE
AGAIN FORCE A SCT-BKN SHALLOW CU FIELD OVER LAND AREAS THROUGH EARLY
THIS EVENING.
AT THE SURFACE...HIGH PRESSURE CENTERED OFF THE SOUTHEAST COAST
RIDGES BACK TO THE WEST ALONG OR JUST NORTH OF THE I-10 CORRIDOR.
THIS POSITION CONTINUES TO PROVIDE OUR LOCAL AREA WITH A LIGHT EAST
TO EAST-SOUTHEAST FLOW. THE UNSEASONABLE TEMPERATURES ALSO CONTINUE
WITH MANY LOCATION ALREADY REPORTING READINGS IN THE LOWER 80S. IT
IS QUITE POSSIBLE THAT A FEW MORE RECORD HIGHS WILL BE BROKEN THIS
AFTERNOON.
&&
.SHORT TERM (TONIGHT THROUGH MONDAY NIGHT)...
TONIGHT THROUGH SUNDAY NIGHT...
STACKED RIDGING WILL KEEP THE WEATHER PATTERN UNCHANGED THROUGH THE
REMAINDER OF THE WEEKEND. OVERNIGHT LOWS WILL MAINLY BE IN THE
LOWER/MID 60S AT THE COAST AND MIDDLE 50S TO AROUND 60 INLAND.
DAYTIME HIGHS CLIMB BACK INTO THE LOWER 80S FOR MANY LOCATIONS
SUNDAY AFTERNOON. LOCAL GRADIENT DOES SLACKEN A BIT DURING THE DAY
ON SUNDAY...AND DUE TO THE UNUSUALLY STRONG LAND BASED HEATING...MAY
SEE A FEEBLE SEA-BREEZE DEVELOP DURING THE AFTERNOON...ESPECIALLY
FROM PINELLAS COUNTY NORTHWARD WHERE THE LAND/SEA TEMPERATURE
GRADIENT WILL BE GREATEST. IF THIS WEAK ONSHORE FLOW DOES DEVELOP
THEN THE IMMEDIATE COAST WOULD END UP A FEW DEGREES COOLER.
REGARDLESS WILL BE FORECASTING ABOVE NORMAL TEMPERATURES FOR ALL.
THE UPPER LEVEL RIDGE OVER-TOP THE INFLUX OF LOW LEVEL ATLANTIC
MOISTURE IS A GOOD SETUP FOR AREAS OF FOG TO DEVELOP ONCE AGAIN
DURING THE LATE NIGHT HOURS...SIMILAR TO EARLY THIS MORNING. BEST
CHANCES FOR THE FOG WILL BE INLAND. SHELF WATER TEMPERATURES HAVE
WARMED BY SEVERAL DEGREES DURING THE PAST WEEK RESULTING IN LESS
POTENTIAL FOR ADVECTION SEA FOG. HOWEVER...WILL CONTINUE TO MONITOR
FOR THIS POSSIBILITY...ESPECIALLY ALONG THE NATURE COAST ZONES.
MONDAY/MONDAY NIGHT...
WARM AND GENERALLY DRY CONDITIONS PREVAIL INTO THE FIRST DAY OF THE
NEW WORK WEEK AS STACKED RIDGING WILL REMAIN IN PLACE. WILL BEGIN TO
SEE THE FIRST SIGNS OF THE EVENTUAL BREAK DOWN OF THE RIDGE BY
MONDAY NIGHT INTO TUESDAY AS HEIGHT FALLS BEGIN TO SPREAD ACROSS THE
SOUTHERN PLAINS AND MIDDLE MS VALLEY. THIS PATTERN WILL EVENTUALLY
PUSH THE UPPER RIDGE EASTWARD AND ALLOW A FRONT TO SLIP INTO OUR
REGION...BUT THIS IS NOT UNTIL THE MID-WEEK PERIOD. MORE ON THIS
FRONT IN THE LONG TERM DISCUSSION BELOW.
&&
.LONG TERM (TUESDAY - FRIDAY)...
AN UPPER LEVEL TROUGH REACHES FROM HUDSON BAY TO THE SOUTHWEST U.S.
WITH A FRONT FROM THE GREAT LAKES TO THE WESTERN GULF COAST WHILE
DEEP RIDGING OFF THE EASTERN SEABOARD EXTENDS TO THE EAST GULF AND
CUBA MON NIGHT. THE UPPER TROUGH SLOWLY WORKS EAST TO THE EASTERN
STATES BY WED...SHIFTING THE DEEP RIDGING TO ALONG AND SOUTH OF
LATITUDE 30 NORTH. THE FRONT SAGS ACROSS THE GULF COAST AND SE U.S.
AND PUSHES INTO FL LATE WED. THIS WOULD SUGGEST SOME POSSIBILITY OF
RAINFALL BUT BOTH MOISTURE AND ENERGY ARE LIMITED AND WILL KEEP
THE FORECAST DRY.
THU-FRI...WHILE THE GFS AND ECMWF HAVE BEEN IN FAIRLY GOOD
AGREEMENT THEY NOW BEGIN TO DIVERGE. THE GFS KEEPS BROAD
TROUGHING OVER THE EASTERN U.S. AS A SURFACE HIGH MOVES OVER THE
GULF COASTAL STATES TO THE ATLANTIC. THIS PATTERN WOULD KEEP THE
AREA DRY AND STABLE. THE ECMWF HAS SIMILAR TROUGHING BUT WITH A
CUT-OFF LOW OVER THE SOUTHERN PLAINS THAT MOVES TO THE CENTRAL
GULF COAST WITH AN ASSOCIATED SURFACE LOW THAT TRAILS A COLD FRONT
ACROSS THE CENTRAL AND EASTERN GULF. THIS WOULD SUGGEST SOME
BETTER...BUT LOW...ODDS OF PRECIPITATION. FOR NOW WILL MAINTAIN A
DRY FORECAST.
INITIALLY WARM TEMPERATURES WILL GRADUALLY DECREASE BUT STILL
REMAIN ABOVE NORMAL.
&&
.AVIATION...
SOME CHANCE OF BRIEF MVFR CEILINGS AROUND 3000 FEET THIS
AFTERNOON...BUT MAINLY BROKEN VFR CEILINGS 3500 TO 5000 FEET. FOG
AND LOW CLOUDS DEVELOP 06-09Z WITH MVFR TO IFR POSSIBLE ALL
TERMINALS AND LIFR POSSIBLE LAL AND PGD.
&&
.MARINE...
THE SURFACE RIDGE REMAINS ALIGNED FROM OFF THE SOUTHEAST COAST BACK
WESTWARD ALONG THE I-10 CORRIDOR. THE RIDGE WILL HOLD POSITION
THROUGH TONIGHT AND THEN SLOWLY SETTLE SOUTHWARD LATER SUNDAY INTO
THE EARLY PORTION OF NEXT WEEK. NO MARINE HEADLINES ARE ANTICIPATED
THROUGH THE EARLY PORTION OF THE WEEK. THE NEXT COLD FRONT IS
EXPECTED TO ARRIVE ACROSS THE EASTERN GULF OF MEXICO BY WEDNESDAY OR
WEDNESDAY NIGHT.
&&
.FIRE WEATHER...
SURFACE AND UPPER LEVEL HIGH PRESSURE WILL REMAIN IN CONTROL OF THE
FORECAST AREA THROUGH MONDAY KEEPING OUR WEATHER GENERALLY DRY WITH
ABOVE AVERAGE TEMPERATURES. DESPITE THE WARM DAYTIME TEMPERATURES...
THE SURFACE RIDGE POSITION OFF THE SOUTHEAST COAST WILL PROVIDE A
STEADY INFLUX OF LOW LEVEL ATLANTIC MOISTURE AND PREVENT ANY
WIDESPREAD AREAS OF CRITICALLY LOW RELATIVE HUMIDITY. THE NEXT COLD
FRONT IS NOT ANTICIPATED TO ARRIVE UNTIL LATER WEDNESDAY OR
WEDNESDAY NIGHT. A MORE SEASONABLE AIRMASS IS ANTICIPATED TO ARRIVE
BEHIND THIS FRONT FOR THE LATER PORTION OF NEXT WEEK.
&&
.PRELIMINARY POINT TEMPS/POPS...
TPA 64 81 64 80 / 0 0 10 0
FMY 64 83 62 82 / 0 0 0 0
GIF 59 82 58 82 / 0 0 0 0
SRQ 62 79 60 79 / 0 0 0 0
BKV 57 83 55 81 / 0 0 10 0
SPG 65 79 64 78 / 0 0 0 0
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GULF WATERS...NONE.
&&
$$
SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA
AVIATION...JILLSON
LONG TERM...RUDE
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
303 PM CST SAT JAN 12 2013
.SYNOPSIS...
COLD FRONT PUSHING INTO THE OHIO VALLEY THIS AFTERNOON...WITH COLD
AIR OOZING INTO THE UPPER MISSISSIPPI VALLEY BEHIND IT. LONG WAVE
TROUGH SPANNING THE ROCKIES...WITH ENERGY LIFTING OUT OVER THE
CENTRAL US IN FAST SOUTHWEST FLOW. LEAD SHORTWAVE GENERATING SOME
SNOW/SLEET OVER NORTHERN MO AND INTO SE IA AT THIS TIME. MAIN
PRECIP AREA ACROSS SOUTHERN MO AND SOUTHERN ILLINOIS IS ALSO
EXPANDING NORTHWARD AND IS NOW PUSHING INTO CENTRAL ILLINOIS AHEAD
OF THE MAIN SHORT WAVE...WHICH CAN BE SEEN ON SATELLITE LIFTING OUT
OF ARKANSAS.
&&
.SHORT TERM...TONIGHT AND SUNDAY...
MAIN FORECAST QUESTIONS THIS AFTERNOON CENTER AROUND DEVELOPING
PRECIPITATION EVENT FOR TONIGHT. THE INITIAL WAVE OF LIGHT SNOW/SLEET
NOW MOVING ACROSS EASTERN IA WILL HELP COOL AND SATURATE THE COLUMN
AHEAD OF TONIGHTS WAVE BUT WILL HAVE LITTLE OTHER IMPACT. FOR TONIGHT...OF
THE SHORT RANGE MODELS...THE RAP IS THE MOST AGGRESSIVE WITH
SNOWFALL AMOUNTS...SUGGESTING 4 TO 6 INCHES ALONG AND EAST OF THE
MISSISSIPPI RIVER. MEANWHILE...THE NAM...GFS...AND ECMWF ARE MORE
CONSERVATIVE WITH 2-3 INCHES AT MOST. THUS WILL FAVOR A BLEND OF
THE NAM AND ECMWF FOR THIS FORECAST...ESPECIALLY FOR MOISTURE PARAMETERS.
THERE IS CONSISTENCY IN THE FORECAST SOUNDINGS...SHOWING A LARGE
WEDGE OF WARM AIR ALOFT...ESPECIALLY EAST OF THE MISSISSIPPI
RIVER...THAT WILL HAVE TO COOL BEFORE PRECIP CHANGES TO SNOW.
CURRENT THINKING IS THAT NEAR THE RIVER THE PERIOD OF SLEET SHOULD
BE BRIEF...BUT WILL LAST LONGER AS YOU GO EAST. BUREAU/PUTNAM
COUNTIES COULD SEE A COUPLE OF HOURS OF SLEET BEFORE IT CHANGES TO
SNOW BY MIDNIGHT. IT IS ALSO NOT OUT OF THE QUESTION FOR A BRIEF
PERIOD OF FREEZING RAIN TO FALL AT ONSET IN THE BUREAU/PUTNAM
COUNTY AREA. HOWEVER...IF THIS WOULD OCCUR...THE EVAPORATIVE
COOLING WOULD QUICKLY CHANGE IT TO SLEET. AND WITH THE WARM
TEMPERATURES THESE LAST FEW DAYS...ONLY ELEVATED SURFACES SHOULD
BE AT RISK FOR FREEZING.
IN TERMS OF SNOW AMOUNTS...THE GARCIA METHOD WOULD SUGGEST 2-4 INCHES
IN THE HEAVIEST BAND FROM THE QUAD CITIES NORTHEASTWARD. THE MODEL TIME
SECTIONS DO SUPPORT THIS...SHOWING POTENTIAL FOR DENDRITIC GROWTH
IN THAT SAME AREA. WHILE DENDRITES WOULD INCREASE AMOUNTS...THE SHORT
DURATION OF THE EVENT AND ANY SLEET AT ONSET WILL LIMIT THE
ACCUMULATIONS.
THE BOTTOM LINE IS THAT I EXPECT A SHARP CUT-OFF IN SNOW ACCUMULATIONS
SOMEWHERE IN THE VICINITY OF THE 380 CORRIDOR...THE HEAVIEST SNOW
AMOUNTS IN THE 2-4 INCH RANGE FROM NEAR THE QUAD CITIES NORTHEASTWARD
TO FREEPORT...AND A LONGER PERIOD OF SLEET WITH LESSER SNOW
ACCUMULATIONS AS YOU MOVE TOWARD THE PRINCETON ILLINOIS AREA. THE
MAIN PRECIP EVENT WILL BEGIN AFTER 6 PM TONIGHT...CHANGING TO SNOW
AREA WIDE BY MIDNIGHT AND SHOULD HAVE EXITED ALL BUT THE EXTREME
EASTERN PORTIONS OF THE CWFA BY 6 AM.
DMD
.LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY...
SUNDAY NIGHT AND MONDAY...LATEST 12Z RUN MODELS IN GOOD AGREEMENT OF
SUGGESTING SFC RIDGING SLIDING ACRS THE REGION FROM THE WEST SUNDAY
NIGHT...WHILE CONFLUENT FLOW REGION WEST OF L/W TROF TRYING TO
PHASE ACRS THE EASTERN ROCKIES. EXPECT CLEARING SKIES AS HIGH CLOUDS
NORTHWEST OF LLVL BAROCLINIC REGION PUSH EASTWARD...COMBINED WITH
DECREASING WINDS FOR A COLD NIGHT OVER FRESH SNOW COVER. SOME SINGLE
DIGITS POSSIBLE BY EARLY MON MORNING. MAINLY CLEAR SKIES AND COLD
CONDITIONS TO FINISH OUT THE PERIOD WITH HIGHS IN THE 20S MON AND
SINGLE DIGITS TO LOWER TEENS MON NIGHT. SOME LIGHT RETURN FLOW MAY
MAKE FOR NON-DIURNAL TEMP TRENDS PRE-DAWN EARLY TUE MORNING WEST OF
THE MS RVR.
TUESDAY AND WEDNESDAY...LATEST RUN MEDIUM RANGE SOLUTIONS SUGGEST
THE ABOVE MENTIONED LONG WAVE TROF AXIS WILL SHEAR ACRS THE MID
CONUS THIS PERIOD FROM THE GRT LKS...ALL THE WAY TO THE BAJA OF MEX.
UPPER RIDGE ALONG AND JUST OFF THE WEST COAST AMPLIFIES...EVENTUALLY
DUMPING RIDGE-RIDING WAVE ENERGY DOWN ACRS THE UPPER MIDWEST AND GRT
LKS THROUGH MID WEEK. HOW FAR SOUTH THIS CLIPPER TYPE WAVE WILL
EVENTUALLY DIG IS STILL SOMEWHAT UNCERTAIN...ALL LONGER RANGE MODEL
SOLUTIONS BUT THE 12Z GFS KEEP LEAD WAVE AND IT/S ASSOCIATED PRECIP
TO THE NORTH OF THE AREA UNTIL MAYBE WED NIGHT WHEN SOME FLURRIES
MAKE IT ACRS THE NORTHEASTERN THIRD OF THE AREA/CWA UNDER RE-
ENFORCING CYCLONIC FLOW DIGGING ACRS THE SOUTHWESTERN GRT LKS. THE
12Z GFS IS MORE PROGRESSIVE AND DEEPER SOUTH WITH THE CLIPPER AND
PRODUCES LIGHT SNOW ACRS MOST OF THE LOCAL AREA TUE NIGHT INTO WED
MORNING BEFORE SHUTTLING QUICKLY OFF TO THE EAST. FOR NOW WILL SIDE
WITH THE MAJORITY AND KEEP THE FCST DRY...WITH THERMAL MODERATION
FROM THE SOUTHWEST AHEAD OF THE NORTHERN STREAM CLIPPER. HIGHS TUE
NEAR 30...MAY TRANSLATE INTO THE 30S BY WED BEFORE COLD FRONT OFF
THE PASSING CLIPPER SYSTEM TO THE NORTH SWEEPS THROUGH THE CWA BY
LATE WED.
THURSDAY THROUGH SATURDAY...LATEST RUN MEDIUM RANGE MODEL SOLUTIONS
AND ENSEMBLES GENERALLY SUGGEST WHILE A TYPE OF REX BLOCK SETS UP
ACRS THE WEST COAST AND SOUTHWESTERN U.S...BROAD UPPER LEVEL
TROFFINESS SETS UP ACRS MUCH OF THE EASTERN CONUS SOUTH OF NORTHERN
HUDSON BAY POLAR VORTEX. A RIBBON OF LLVL BAROCLINICITY SETS UP
PARALLEL TO THIS FEATURE FROM SOUTH CENTRAL CANADA...TO THE MID
ATLANTIC WHILE A BUILDING DOME OF VERY COLD AIRMASS LOOMS ACRS THE
EASTERN TWO THIRDS OF CANADA. WHILE THE REAL COLD AIR REMAINS BOTTLED
UP BY THIS PATTERN...WILL CONTINUE TO ADVERTISE MODERATING TEMPS
THROUGH SAT. DRY CONDITIONS TOO AS ANY IMPULSES WILL LOOK TO RIPPLE
ALONG THE BAROCLINIC RIBBON AND PRODUCE PRECIP MAINLY OT THE NORTH
ACRS THE DAKOTAS...MN...WI AND THE NORTH HALF OF THE GRT LKS INTO
SAT NIGHT. SOME LONGER RANGE SIGNS OF PLUNGING JET ENERGY TO ALLOW
SOME OF THE ARCTIC AIR TO BREAK LOOSE AND SPILL ACRS THE WESTERN
GRT LKS BY EARLY NEXT WEEK. ..12..
&&
.AVIATION...
A WINTRY MIX WILL OVERSPREAD THE AREA THIS EVENING. SITES ALONG
AND WEST OF THE MISSISSIPPI RIVER COULD SEE A BRIEF PERIOD OF
SLEET AT ONSET WHICH WILL RAPIDLY CHANGE OVER TO SNOW. EAST OF THE
MISSISSIPPI RIVER...ROUGHLY FROM PRINCETON IL TO MACOMB
IL...PRECIPITATION IS EXPECTED TO BEGIN WITH A BRIEF PERIOD OF
FREEZING RAIN EARLY THIS EVENING...CHANGING TO SLEET FOR SEVERAL
HOURS...AND THEN FINALLY OVER TO SNOW AROUND MIDNIGHT. AREA
WIDE... SNOWFALL RATES WILL BE MOST INTENSE BETWEEN 3Z AND 9Z
OVERNIGHT... AND SNOW IS EXPECTED TO END BY 12Z. OTHERWISE... BY
02Z LOOK FOR PREDOMINANTLY MVFR CIGS AND VSBYS WITH LOCAL IFR IN
HEAVIER PRECIPITATION.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR CLINTON-DES MOINES-JACKSON-LEE-LOUISA-MUSCATINE-
SCOTT.
IL...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR BUREAU-CARROLL-HANCOCK-HENDERSON-HENRY IL-JO
DAVIESS-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-STEPHENSON-
WARREN-WHITESIDE.
MO...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM CST
SUNDAY FOR CLARK.
&&
$$
DMD/12/DMD
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
245 PM EST SAT JAN 12 2013
.SYNOPSIS...
CROSSING LOW PRESSURE WILL SPREAD RAIN OVER THE UPPER OHIO VALLEY
REGION ON SUNDAY...AND WILL PULL A COLD FRONT THROUGH BY MONDAY.
&&
.NEAR TERM /THROUGH SUNDAY/...
SHRA AREA WITH SHRTWV IN SWLY FLOW ALOFT WAS MOVG ACRS KY THIS
AFTN...AND THAT CLUSTER IS EXPECTED TO DVLP UP THE OH RIVER AND
SHOULD AFFECT THE AREA LTR THIS EVE. EVE PRECIP PROBABILITIES HAVE
BEEN ADJUSTED FOR THIS POTENTIAL USING RAP HRLY OUTPUT...AND
BASICALLY FOCUS THE BTR SHRA CHCS OVR AREAS WEST OF PITTSBURGH
BEFORE THE DISTURBANCE LIFTS NWD LTR TNGT.
OTHERWISE...VERY WARM TEMPERATURES CAN BE EXPECTED THROUGH SUNDAY
AS DETERMINISTIC MODELS HAVE CONTINUED THE TREND OF HOLDING FRONT
TO THE WEST OF THE REGION THROUGH THE NEAR TERM. IN ADDITION...THE
HEAVIER RAIN POTENTIAL WILL ALSO BE SHIFTED WEST WITH THE
BOUNDARY...THUS LIMITING RAIN AMOUNTS FOR MOST COUNTIES AS WELL AS
ALLOWING MORE RUNOFF TIME FOR THE LAST OF THE SNOW MELT.
THE FORECAST THUS FEATURES REDUCED PRECIP PROBABILITIES FOR LATE
TNGT AND EARLY SUNDAY...ALTHOUGH CHC NMBRS HAVE GENLY BEEN MAINTAINED
UNTIL LOW PRES SWEEPS ACRS OHIO DURING THE AFTN. CATEGORICAL NMBRS
HAVE BEEN RECONSTRUCTED FOR THAT EVENTUALITY WITH RAIN AMOUNTS
APPROACHING AN INCH LIMITED TO AREAS ALONG AND NORTH OF A ZANESVILLE
TO FRANKLIN LINE.
GIVEN THIS SCENARIO...STREAM AND RIVER RISES CAN BE EXPECTED...BUT
FLOODING IS NOT ANTICIPATED.
THE WARM NEAR TERM TEMPS WERE FORECAST USING LAMP GUIDANCE AND
PERSISTENCE FOR SUNDAY.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
A TAPERING OF POPS TO LIKELY NMBRS WAS COMPLETED FOR SUNDAY
EVE...AND TO CHC NMBRS THEREAFTER AS THE AFOREMENTIONED LOW DRAGS
THE COLD FRONT OVR THE UPR OH REGION WITH ITS EXIT. RESIDUAL RAIN
SHOWERS MAY CHANGE TO SNOW BY MONDAY MRNG...BUT NO SIGNIFICANT
ACCUMULATION IS FORTHCOMING.
THE LATEST NAM AND GFS ARE IN AGREEMENT IN DEPICTIONS OF
SUFFICIENT SWD PENETRATION OF THE FRONT FOR DRY WEATHER FOR MOST
ZONES...AND A STEADY POP REDUCTION FOR SERN COUNTIES ON MONDAY.
THOSE MDLS ALSO INDICATE DVLPMNT OF LOW PRES ALNG THE FRONT ON
TUESDAY. THAT SYSTEMS PROGRESS ACRS THE VIRGINIAS MAY SPREAD PCPN
OVR AREAS ARND AND SE OF MORGANTOWN...AND WARM ADVCTN ABOVE THE
BNDRY LYR MAY BE SUFFICIENT FOR A PERIOD OF FREEZING RAIN WITH THE
LIGHT SNOW FOR THE RIDGE ZONES.
FOR NOW...LOW CHC POPS WL SUFFICE FOR THAT SITUATION AS THE BETTER
POTENTIAL LKS TO BE FARTHER SOUTH AND EAST.
SHORT TEMPS WERE FORECAST USING A BLEND OF GUIDANCE AND GENERALLY
FEATURE A SLOWER COOLING TREND.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
SVRL WEAK AND FAST MOVG SYSTEMS ARE EXPD THRU THE PD. WITH TIMING
DETAILS DIFFERING AMONG THE MODELS...PREFERRED AN ECMWF/HPC CHART
BLEND TO SMOOTH OUT SOME OF THE DIFFERENCES.
EXPCTG HIGH PRES TO BLD IN TUE NGT INTO WED. A COLD FRONT IS EXPD TO
DROP SE ACRS THE GT LKS RGN WED NGT INTO THU WITH A CHC OF SHSN...BUT
MOISTURE IS LMTD. A FEW SHSN MAY LINGER IN COLD WRLY FLOW THRU THU
NGT BEFORE ANOTHER WK SYSTEM SKIRTS THE NRN PTN OF THE CWA FRI. YET
ANOTHER WK COLD FRONT IS EXPD FOR SAT. MAY SEE JUST ENOUGH WARM AIR
AHEAD OF IT FOR A MIX OF SHRA/SHSN...BUT AGAIN MOISTURE SHOULD BE
LMTD. WENT NR OR A LTL BLW HPC TEMP GUIDANCE...RESULTING IN NR OR
SLIGHTLY ABV NRML TEMPS THRU THE PD.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
LOW LVL MOISTURE WL CONT TO BRING OCNL MVFR CIGS TO MOST OF THE TAF
SITES THROUGH THIS AFTN...EXCPT IFR FOR FKL AND DUJ. THINK THE LWR
CIGS WL SCT OUT BY THIS EVE...THEN IFR REDVLPS FOR FKL AND DUJ OVRNGT.
WITH MID LVL CLDS NOT CERTAIN REST OF THE TAF SITES WL SEE SGFNT
RESTRICTIONS...BUT WL HAVE TO MONITOR FOR THIS THRU THE EVE. LLVL JET
MOVG IN OVRNGT WL BRING A LLWS POTENTIAL AFTR 08-10Z MOST PLACES.
SHOULD GET SOME LMTD MIXING AFT 15Z SUN SO ENDED LLWS EXCPT FOR
FKL/DUJ WHERE LOW CLDS SHOULD LIMIT MXG. A COLD FRONT WL APRCH FM
THE WEST SUN...AND MENTIONED SHRA AT ZZV BY LT MRNG...AND LT AFTN
FOR PIT.
.OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/...
RESTRICTIONS ARE EXPD SUN NGT INTO MON AS THE COLD FRONT MOVES THRU
THE AREA. RESTRICTIONS ARE PSBL AGAIN WED NGT AND THU AS ANOTHER COLD
FRONT MOVES THRU.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...NONE.
WV...NONE.
&&
$$
15/07
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1246 PM EST SAT JAN 12 2013
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 534 AM EST SAT JAN 12 2013
WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM
NW ONTARIO INTO THE SW CONUS AND A RIDGE OVER THE EAST RESULTING IN
SW FLOW FROM THE SRN PLAINS INTO THE WRN GREAT LAKES. A SHEARED
SHORTWAVE TROUGH WAS LIFTING NORTHEAST THROUGH NRN MN. AT THE
SFC...A 993 MB LOW WAS LOCATED OVER THE MN ARROWHEAD WITH A COLD
FRONT EXTENDING TO THE SSE THROUGH NW INTO CNTRL WI. VERY MILD SSW
FLOW AHEAD OF THE FRONT HAS PUSHED TEMPS INTO THE LOWER 40S ACROSS
MOST OF UPPER MI. GUSTY SW WINDS HAVE DEVELOPED BEHIND THE COLD
FRONT AS A 5MB/3HR PRES RISE MAX TRAILS THE FRONT OVER SRN MN.
RADARS INDICATED AREAS OF LIGHT PCPN OVER ERN MN INTO NW WI WITH NO
RETURNS TO THE EAST.
MAIN FCST CONCERNS ARE WINDS AND LAKE EFFECT SNOW POTENTIAL.
TODAY...MODELS HAVE BEEN CONSISTENT WITH THE LOW QUICKLY LIFTING
NORTHEAST TO JAMES BAY BY LATE TODAY. THIS WILL DRAG THE COLD FRONT
THROUGH THE CWA BY 18Z BRINGING THE STRONGEST ISALLOBARIC GRADIENT
THROUGH THE WEST HALF OF UPPER MICHIGAN THIS MORNING. WITH STRONG
CAA AND INCREASE IN MIXED LAYER DEPTH...GUSTY WINDS IN THE 25 TO 35
MPH RANGE ARE EXPECTED OVER MOST OF THE REGION. SINCE THE SW WINDS
ARE MAINLY PARALLEL TO THE KEWEENAW PENINSULA THE STRONGER GUSTS ARE
EXPECTED DURING THE AFTERNOON AS WINDS VEER MORE TO THE WSW. THIS
WOULD BRING THE STRONGEST GUSTS MAINLY ACROSS THE WESTERN SHORE OF
THE KEWEENAW. A WIND ADVISORY IS IN EFFECT WHICH HIGHLIGHTS THESE
LOCATIONS. BY THE TIME THAT WINDS VEER TO THE WEST WHICH WOULD FAVOR
LOCATIONS IN THE HIGHER TERRAIN AROUND CMX...THE GRADIENT WEAKENS.
LAKE INDUCED CAPE VALUES CLIMB QUICKLY TO AROUND 300-400 J/KG BY
LATE AFTERNOON AS 850 MB TEMPS FALL TO NEAR -15C. THE STRONGEST LOW
LEVEL CONVERGENCE AND GREATEST LES IS EXPECTED TO FOCUS TOWARD THE
NRN PORTION OF THE KEWEENAW....FROM CMX NORTHWARD.
TONIGHT...INSTABILITY OVER THE LAKE WILL INCREASE AS 850 MB TEMPS
DROP TO AROUND -18C. THE HIGHER RES MODELS SUGGEST THAT EVEN AS THE
WINDS OVER WRN LAKE SUPERIOR VEER MORE TO THE NW...LAKE INDUCED
TROUGHING WILL KEEP THE CONVERGENT WINDS OVER THE KEWEENAW. EVEN
THOUGH INVERSION HEIGHTS ARE ONLY FCST NEAR 4K FT...WITH THE
MOISTURE DEPTH TO AT LEAST 7K FT...AT LEAST MODERATE INTENSITY LES
IS EXPECTED THAT COULD BRING 2 TO 4 INCHES TO LOCATIONS FROM NE
ONTONAGON COUNTY THROUGH THE HIGHER TERRAIN OF THE KEWEENAW
PENINSULA. A LES ADVISORY WAS POSTED WHICH EXTENDS THROUGH SUNDAY
NIGHT(DETAILS IN SUBSEQUENT DISCUSSION).
A SHORTWAVE MOVING TOWARD THE GREAT LAKE FROM THE CNTRL PLAINS ALONG
WITH UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF THE 170 KT 300 MB
JET INTO NRN ONTARIO WILL ALSO SUPPORT AN AREA OF LIGHT SNOW THAT
WILL GRAZE THE SE PORTIONS OF THE CWA. SINCE THE HEAVIER PCPN IS
EXPECTED TO THE SOUTH...ACCUMULATIONS ARE EXPECTED TO REMAIN BELOW
AN INCH.
.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 534 AM EST SAT JAN 12 2013
AREA WILL BE ENTERING BACK INTO A MORE WINTER TIME PATTERN
TODAY...WHICH WILL CONTINUE THROUGH THE LONG TERM PERIOD.
SYSTEM MOVING THROUGH THE LOWER GREAT LAKES TONIGHT INTO SUNDAY HAS
HAS SHIFTED A LITTLE MORE TO THE NORTHWEST OVER THE LAST FEW RUNS
AND NOW BRUSHES THE COUNTIES NEAR LAKE MICHIGAN WITH SOME LIGHT SNOW
SUNDAY MORNING. THIS NORTHWEST SHIFT HAS CAUSES THE DEEPER MOISTURE
WITH A LEFT OVER SHORTWAVE FROM THE LOW CURRENTLY IN MN TO REMAIN
JUST TO THE WEST OF LAKE SUPERIOR ON SUNDAY MORNING AND THE FIRST
PART OF THE AFTERNOON. THIS LEADS TO SOME CONCERN FOR THE INITIAL
LAKE EFFECT FROM LINGERING SURFACE TROUGH OVER SOUTHERN LAKE
SUPERIOR. SINCE THE COLD AIR SURGE EXPECTED TODAY INTO TONIGHT WILL
BE FAIRLY SHALLOW...IT WILL SETUP A VERY STRONG INVERSION TONIGHT
AROUND H800 OR 5KFT. THUS...DO EXPECT LAKE EFFECT TO BE OCCURRING
OVER THE WEST-NORTHWEST FAVORED LOCATIONS IN THE WESTERN U.P.
BUT HAVE SOME CONCERNS ON STRENGTH TO START THE PERIOD. ON THE
POSITIVE SIDE...THE BEST FORCING WILL BE FOCUSED IN THE DGZ...BUT
THERE IS SOME SHEAR IN THE CLOUD LAYER...SFC-H925 WINDS OUT OF THE
NORTHWEST AND H850 WINDS OUT OF THE WEST IN THE MORNING AND THEN
SOUTHWEST IN THE AFTERNOON. WONDERING IF THIS WILL KEEP THE FOCUS
AWAY FROM A DOMINATE BAND IN MORE GENERAL MULTIBAND LAKE EFFECT.
LAKE EFFECT SNOW PARAMETER...WHICH HAS DONE A GOOD JOB HIGHLIGHTING
THE FEW LAKE EFFECT EVENTS WE HAVE HAD THIS SEASON...KEEPS VALUES
LIMITED DURING THE MORNING HOURS AND WILL KEEP SNOWFALL AMOUNTS
LIGHTER.
ONCE THE SURFACE LOW SLIDES NORTHEAST INTO WESTERN QUEBEC SUNDAY
AFTERNOON AND EVENING...THEN THE SURFACE TROUGH WILL SLIDE SOUTH
SLIGHTLY LEADING TO LESS SHEAR AND RISING INVERSION HEIGHTS TO
6-7KFT DUE TO DEEPER MOISTURE IN MN BEING DRAGGED THROUGH THE
WESTERN CWA. LAKE EFFECT SNOW PARAMETER PEAKS TO 2 IN THIS
PERIOD...SO EXPECT INTENSITY OF THE LAKE EFFECT TO FOLLOW SUIT. AT
THIS POINT...THINK IT WILL BE IN NORTHWEST FAVORED LOCATIONS
ALTHOUGH HIGHER RESOLUTION MODELS ARE TRYING TO HINT AT ENHANCED
CONVERGENCE IN THE HOUGHTON/ONTONAGON/GOGEBIC COUNTY AREA. CHECKLIST
GIVES 3-5IN PER 12HRS FOR SUNDAY AND SUNDAY NIGHT AND THAT SEEMS TO
FIT WELL WITH THE GOING FORECAST...AS SNOW RATIOS WILL BE IN THE
20-30 TO 1 RANGE. WITH TOTAL SNOW FROM TONIGHT THROUGH SUNDAY NIGHT
OF 7 TO LOCALLY 14 INCHES...WILL ISSUE AN ADVISORY FOR KEWEENAW
THROUGH ONTONAGON COUNTIES. WILL NEED TO WATCH GOGEBIC COUNTY NEAR
THE PORCUPINE MOUNTAINS...AS ARE HINTS OF ENHANCED CONVERGENCE FOR
HIGHER SNOWFALL AMOUNTS THERE.
FARTHER EAST...WITH THE LIGHT SYNOPTIC SNOW LEAVING EARLY SUNDAY
AFTERNOON...TRANSITION WILL OCCUR TO LAKE EFFECT IN THE NORTHWEST
WIND BELTS IN THE AFTERNOON...AS THE SURFACE TROUGH SHIFTS WINDS.
THERE TOO...AMOUNTS WILL BE LIGHT TO MODERATE ON SUNDAY AFTERNOON
INTO THE EVENING...BUT COULD PEAK UP SOME AFTER MIDNIGHT WHEN THE
INVERSION HEIGHTS RISE. MAY NEED AN ADVISORY ON FUTURE SHIFTS FOR
THE SUN AFTERNOON/NIGHT PERIOD.
SURFACE TROUGH THEN SHIFTS NORTH ON MONDAY...PUSHING THE SNOW
OFFSHORE OVER THE EAST AND FOCUSES IT OVER THE KEWEENAW IN THE
WEST. INTENSITY SHOULD WEAKEN SOME AS THE DEEPER MOISTURE DEPARTS
AND INVERSION HEIGHTS DROP TO 5-6KFT. WITH THE CLOUD FOCUSED IN THE
DGZ...STILL SHOULD SEE GOOD SNOW RATIOS AND LIGHT SNOWFALL
ACCUMULATIONS IN THE 1-3 INCH RANGE FOR THE KEWEENAW.
SURFACE LOW DEVELOPS OVER EASTERN LAKE SUPERIOR MONDAY NIGHT AND
ENHANCES A SURFACE TROUGH OVER THE CENTRAL AND WESTERN PORTIONS OF
LAKE. MEANWHILE...DEEPER MOISTURE SLIDES THROUGH ASSOCIATED WITH A
SHORTWAVE MOVING THROUGH THE NORTHERN STREAM NORTHWEST FLOW. THERE
WILL LIKELY BE A STRONGER...DOMINATE LES BAND ASSOCIATED WITH THIS
TROUGH...BUT MODELS VARY ON THE EXACT LOCATION. AREA NEAR THE TIP OF
THE KEWEENAW WILL HAVE THE BEST CHANCE FOR SEEING THIS BAND LATE
MONDAY NIGHT INTO TUESDAY...SO WILL HIGHLIGHT HIGHER POPS/SNOWFALL
THERE. LES SHOULD DIMINISH TUESDAY AFTERNOON...AS WEAK RIDGING ALOFT
PRODUCES DRIER AIR AND WAA AHEAD OF THE NEXT SHORTWAVE.
THE NEXT SHORTWAVE AND ASSOCIATED CLIPPER LOW WILL MOVE ACROSS THE
CWA ON WEDNESDAY INTO WEDNESDAY EVENING. AS IS NORMALLY THE
CASE...THE GFS IS ON THE FAST SIDE AND THE ECMWF/GEM ARE ABOUT
6-12HRS BEHIND. WILL FOLLOW THAT IDEA FOR POPS AND THINK MOST AREAS
WILL SEE A DUSTING TO AN INCH OF SYNOPTIC SNOW.
POLAR VORTEX IS EXPECTED TO DROP SOUTH RIGHT BEHIND THIS WAVE AND
LEAD TO SOME OF THE COLDEST TEMPERATURES OF THE WINTER SEASON FOR
UPPER MICHIGAN. MODELS HAVE BEEN STRUGGLING WITH THIS PERIOD...DUE
TO THE PHASING OF THE NORTHERN/SOUTHERN STREAMS OF THE UPPER JET IN
THE EASTERN CONUS ON THURSDAY...BUT THE GENERAL IDEA OF COLD
WEATHER IS THERE. THE HPC PREFERRED BLEND OF ECMWF/ECENS MEAN SEEMS
TO BE THE WAY TO GO WITH THE GFS JUMPING 15C AT H850 FROM RUN TO
RUN. THIS COLD AIR...H850 TEMPS ON THE ECMWF IN THE MID -20S WILL
EASILY LEAD TO LAKE EFFECT SNOW IN THE NORTHWEST WIND LOCATIONS.
DELTA-T VALUES SHOULD BE FAIRLY IMPRESSIVE...IN THE UPPER 20S BUT
THE COLD AIR WILL PUSH THE DGZ TOWARDS THE SURFACE AND PRODUCE A
LESS FLUFFY /PLATES OR COLUMNS/ SNOW. WILL KEEP THE SAME IDEA AS
THE PREVIOUS SHIFT OF HIGH END LIKELY POPS FOR WEDNESDAY NIGHT INTO
FRIDAY FOR NORTHWEST AND EVENTUALLY WEST-NORTHWEST FAVORED
LOCATIONS. ONE FINAL ITEM TO NOTE DURING THIS PERIOD IS THE 00Z
GEM/GFS ARE BOTH SHOWING A CLIPPER MOVING THROUGH THE UPPER
MISSISSIPPI VALLEY ON THURSDAY INTO THURSDAY NIGHT...WHILE
THE ECMWF IS ABOUT A DAY LATER AND MAY BRUSH THE CWA.
HIGHS FOR THE PERIOD WILL BE IN THE TEENS TO MIDDLE 20S...WITH THE
COLDEST HIGHS EXPECTED ON THURSDAY/FRIDAY. LOWS WILL ALSO BE NEAR
NORMAL...WITH VALUES IN THE SINGLE DIGITS TO MIDDLE TEENS ABOVE
ZERO.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1246 PM EST SAT JAN 12 2013
MVFR CONDITIONS ARE COMMON...EXCEPT HIGH END MVFR TO LOW END VFR
CEILINGS AT SAW /THANKS TO THE DOWNSLOPE CONDITIONS AT SAW/. STRONG
WSW GUSTS OF 25 TO 33KTS CONTINUE AT ALL 3 SITES...STRONGEST AT CMX
GIVEN THE HIGHER ELEVATION AND MORE FAVORABLE WIND DIRECTION...AND
LOCATION CLOSER TO THE EXITING SURFACE LOW. THE STRONG GUSTY WINDS
WILL DIMINISH SIGNIFICANTLY AROUND SUNSET...AS THE LOW QUICKLY
SHIFTS INTO WESTERN QUEBEC. SNOW SHOWERS EVIDENT ON THE DLH RADAR
WILL SLOWLY PUSH ACROSS W UPPER MI THIS AFTERNOON...WITH THE
CONTINUED STRONG WINDS BRINGING THE POTENTIAL FOR BLOWING SNOW TO
MAINLY CMX PRIOR TO 02Z. IFR TO LOW MVFR VIS CAN THEN BE EXPECTED TO
LINGER THROUGH THE MID MORNING HOURS AT CMX...WITH MAINLY MVFR
CONDITIONS TO VFR CONDITIONS AT IWD AND SAW RESPECTIVELY.
&&
.MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)
ISSUED AT 534 AM EST SAT JAN 12 2013
LOW PRESSURE ACROSS NE MN WILL MOVE NORTHEAST TO JAMES BAY LATE TODAY
BRINGING GALES ACROSS LAKE SUPERIOR. STRONG SW GALES OF 35 WILL
DEVELOP TOWARD DAYBREAK ACROSS THE WESTERN LAKE BEHIND THE COLD FRONT
AND INCREASE TO 40-45KTS. EXPECT THE GALES TO DIMINISH AS THE
STRONGEST WINDS SLOWLY EDGE SE...AS WINDS BEGIN TO TURN W BY LATE
AFTERNOON.
A TROUGH AVERAGING WILL LINGER ACROSS LAKE SUPERIOR THROUGH
SUNDAY...BEFORE SLOWLY WEAKENING AS STRONGER 30.4 INCH HIGH PRESSURE
EXPANDS ACROSS CENTRAL CANADA THROUGH THE CENTRAL PLAINS STATES
THROUGH MONDAY. NW WINDS COULD AGAIN GUST TO NEAR 30KTS OVER SE LS
SUNDAY NIGHT. LOW PRESSURE OVER MANITOBA AND ND TUESDAY NIGHT WILL
LIKELY PUSH ACROSS ONTARIO AND THE UPPER GREAT LAKES ON WEDNESDAY.
ANOTHER PERIOD OF SW-W 30-35KTS WINDS WILL BE POSSIBLE TUESDAY
AFTERNOON INTO THE EVENING HOURS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 5 PM THIS AFTERNOON TO 7 AM EST
MONDAY FOR MIZ001-003.
WIND ADVISORY UNTIL 8 PM EST THIS EVENING FOR MIZ001-003.
LAKE EFFECT SNOW ADVISORY FROM 10 PM THIS EVENING TO 7 AM EST
MONDAY FOR MIZ002.
LAKE SUPERIOR...
GALE WARNING UNTIL 10 PM EST /9 PM CST/ THIS EVENING FOR LSZ162-
240>246-263>267.
LAKE MICHIGAN...
GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LMZ248-250.
GALE WARNING UNTIL 5 PM EST THIS AFTERNOON FOR LMZ221.
&&
$$
SHORT TERM...JLB
LONG TERM...SRF
AVIATION...KF
MARINE...JLB
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
1225 PM CST SAT JAN 12 2013
.UPDATE...
ISSUED AT 1212 PM CST SAT JAN 12 2013
COLD FRONT EXTENDS FROM JUST NORTHWEST OF FARMINGTON TO AROUND
SALEM ILLINOIS AT THIS TIME. LATEST MODEL GUIDANCE HAS STRENGTHENED
THE WARM NOSE ABOVE THE COLD AIR AT THE SURFACE FOR THIS
EVENING...AND THIS IS BEARING OUT PRETTY WELL IN AMDAR SOUNDINGS
FROM LAMBERT FIELD EARLIER THIS MORNING. RAP SOUNDINGS SHOW THE WARM
NOSE OVER THE STL METRO AREA WILL BE AROUND 7C THROUGH THE EVENING
HOURS...AND WITH THE COLD LAYER ONLY DROPPING TO BETWEEN -4C TO
-5C IT DOESN`T LOOK LIKE THERE`S GOING TO BE ENOUGH COLD AIR TO
FREEZE THE LIQUID ALOFT. FORECAST SOUNDINGS ALONG A LINE FROM
ROLLA TO ST LOUIS TO LITCHFIELD ARE VERY SIMILAR. THEREFORE AM
UPDATING THE FORECAST TO GO WITH MORE FREEZING RAIN THAN SLEET IN
THESE AREAS THIS EVENING AND OVERNIGHT. REMAINDER OF THE WEATHER
TYPES STILL LOOK GOOD WITH A SLEET/SNOW MIX OVER CENTRAL AND
NORTHEAST MISSOURI AND WEST CENTRAL ILLINOIS WHERE COLD AIR WILL BE
DEEPER...AND RAIN CHANGING TO FREEZING RAIN OVER SOUTHEAST
MISSOURI AND SOUTH CENTRAL ILLINOIS.
DEBATING WHETHER OR NOT TO EXTEND THE ADVISORY ANOTHER ROW OF
COUNTIES TO THE SOUTHEAST TO ACCOUNT FOR THE POTENTIAL OF MORE
FREEZING RAIN ACCUMULATION...AND WILL LIKELY HAVE TO EXTEND THE
TIME OF THE ADVISORY OUT BEYOND 06Z TONIGHT.
CARNEY
&&
.SHORT TERM...
ISSUED AT 330 AM CST SAT JAN 12 2013
(TODAY)
A STRONG CDFNT WILL MOVE THROUGH MOST OF THE CWA TODAY BEFORE IT
BEGINS TO STALL IN SERN MO LATER TODAY DUE TO A WAVE OF LOW
PRESSURE WHICH DVLPS UPSTREAM ALONG THE FRONT IN RESPONSE TO AN
UPPER LEVEL DISTURBANCE MOVING OVER THE BDRY IN TX/OK. MANY
LOCATIONS WILL EXPERIENCE NEARLY STEADY OR FALLING TEMPERATURES
THROUGH THE DAY BECAUSE OF THE STRENGTH OF THE CDFNT AND THE
TIMING OF ITS PASSAGE DURING DAYLIGHT HOURS.
STRONG ISENTROPIC ASCENT IS MOST PRONOUNCED ALONG THE 295-305K
SFCS THIS AFTN AHEAD OF AN APPROACHING SHORTWAVE. THIS ASCENT WILL
OCCUR IN THE PRESENCE OF A GREAT DEAL OF MOISTURE FOR MID-JANUARY.
IN PARTICULAR...STANDARDIZED ANOMALY PLOTS OF PW FROM THE 12/00Z
GFS AND 12/03Z SREF SHOW ANOMALIES OF BETWEEN +1 AND +4 STDDEV
ACROSS THE ENTIRE CWA WITH THE HIGHEST VALUES ACROSS THE SERN CWA
BY 00Z. THE NET RESULT OF THE FNTL PASSAGE TODAY ALONG WITH
SEVERAL HOURS OF ASCENT AND PLENTY OF MOISTURE WILL BE PCPN OF
VARIOUS TYPES OCCURRING FROM THIS AFTN THROUGH TONIGHT. THE BULK
OF THE PCPN AS WELL AS THE GREATEST VARIETY OF PTYPES WILL OCCUR
TONIGHT AND THIS IS DISCUSSED IN FURTHER DETAIL BELOW. FOR THIS
AFTN...BUFKIT PROFILES SUPPORT RAIN WHICH MAY BEGIN CHANGING TO
SNOW AND ICE PELLETS ACROSS THE FAR WRN AND NWRN CWA LATE IN THE
AFTN. SCT THUNDERSTORMS WILL ALSO BE POSSIBLE ACROSS THE SERN CWA
SINCE MODELS SHOW SOME MUCAPE ALONG WITH STRONG MOISTURE TRANSPORT
ALOFT.
KANOFSKY
&&
.LONG TERM...
ISSUED AT 357 AM CST SAT JAN 12 2013
(TONIGHT AND SUNDAY)
THE FORECAST PACKAGE...AS IT STANDS NOW...WILL BE DOMINATED BY WHAT
HAPPENS IN THIS PERIOD. BASIC PREMISE OF THE FORECAST REMAINS THE
SAME...BUT THERE HAVE BEEN SOME MODEL TRENDS IN SOME AREAS THAT
COULD MAKE A SIGNIFICANT IMPACT TO THE FORECAST.
MODELS CONTINUE TO SHOW SW UPPER LEVEL FLOW PATTERN WITH A
SIGNIFICANT PIECE OF ENERGY BREAKING APART FROM THE BASE OF THE MAIN
LONGWAVE TROF IN THE FOUR CORNERS REGION TODAY AND RACING NEWD THRU
OUR AREA THIS EVENING. IN ADDITION TO THE LIFT PROVIDED BY THIS
SHORTWAVE WILL BE SEVERAL OTHER STRONG LIFTING MECHANISMS FROM RIGHT
ENTRANCE REGION OF AN UPPER JET...FRONTOGENESIS AT H850-700...WAA...
AND CONVERGENCE FROM NOSE OF LO LEVEL JET...THAT WILL PROVIDE
INTENSE LIFT THRU THE COLUMN ACROSS A WIDESPREAD AREA THIS EVENING.
BUT ALREADY BY 06Z...MUCH OF THIS LIFT IS GONE IN AN INCREASINGLY
DRY COLUMN SEVERELY LIMITING PCPN POTENTIAL LATE TONIGHT AND INTO
SUNDAY MORNING.
THE MAIN MODEL TRENDS FROM 24HRS AGO ARE A STRONGER WEDGE OF WARM
AIR ALOFT...AND MORE PERSISTENT...AS WELL AS JUICIER MOISTURE TO
WORK WITH FROM THE S-SE WHERE PWATS WILL PUSH TO 1.4" WHICH IS
HIGHLY ANOMALOUS FOR MID JANUARY...OFTEN CLIMATOLOGICALLY THE
COLDEST AND BY CONSEQUENCE THE DRIEST TIME OF THE YEAR.
TAKE THE ABOVE AND COUPLE IT WITH THE FACT THAT THE MODELS SEEM TO
BE UNDERESTIMATING THE STRENGTH OF THE COLD AIR AT THE SFC BEHIND
CDFNT NOW PLOWING FROM KIRK-KJLN AT 09Z...COULD MAKE FOR A
POTENTIALLY DANGEROUS WINTRY WX EVENT. BY THIS MEANING THAT THE
ZONE OF MIXED WINTRY PCPN WILL PUSH FURTHER NWWD TOWARDS KUIN-KCOU
AND IT IS LOOKING INCREASINGLY LIKELY THAT A ZONE OF FZRA WILL PUSH
SEWD EDGING THE STL METRO AREA FROM THE NW AND EXTENDING SWWD ALG
I-44 AND NEWD NEAR I-55. THE MOSTLY SNOW ZONE...ROUGHLY ALG-NW FROM
A KUIN-KCOU LINE...IS EXPECTED TO RECEIVE 1-2"...WHILE AREAS FURTHER
SE WILL RECEIVE A POTPOURRI OF WINTRY TYPES...FROM FZRA TO SLEET
WITH SOME SNOW. LIGHT ICE AND SLEET/SNOW ACCUMS ARE EXPECTED BUT IT
WILL NOT TAKE MUCH TO CREATE PROBLEMS.
HAVE HOISTED A WINTER WX ADVISORY FOR THE WINTRY MIX AND SOMEWHAT
HEAVIER SNOW ACCUMS ACROSS ABOUT THE NW HALF OF THE FA FOR THIS
EVENING. PCPN MAY SNEAK IN SOONER...BUT DO NOT EXPECT ACCUMS AT
THIS TIME BEFORE 00Z AND THINGS SHOULD TAPER DOWN SIGNIFICANTLY
AFTER 06Z.
ALSO ADDED THUNDER AND HEAVY RAINFALL MENTION FOR AREAS SE OF STL
METRO BUT HELD OFF ON FFA FOR NOW WITH EXISTING DROUGHT AND LESS
THAN 2" OF RAINFALL EXPECTED. WILL LET DAY CREW TAKE A FINAL LOOK
ON THIS ITEM.
(MONDAY - TUESDAY)
COLD...BUT DRY...WX WILL PREVAIL FOR THIS PERIOD. ON TUESDAY...AN
UPPER LEVEL SHORTWAVE WILL SLIDE THRU AS THE BASE OF THE LONGWAVE
TROF MIGRATES E...BUT LIMITED MOISTURE TO WORK WITH TO LEAVE DRY FOR
NOW.
(WEDNESDAY - FRIDAY)
LONGWAVE UPPER TROF SLIDES TO THE ERN CONUS BUT DE-AMPLIFIES IN THE
PROCESS AND SO WILL GIVE TEMPS A CHANCE TO MODERATE A BIT. STILL
LOOKS DRY AT THIS TIME...WITH SOME MODEL SPREADS SUGGESTING LIGHT
PCPN POTENTIAL FOR THURSDAY...BUT NOT ENOUGH TO INCLUDE IN FCST AT
THIS TIME.
TES
&&
.AVIATION...
ISSUED AT 1151 AM CST SAT JAN 12 2013
DIFFICULT FORECAST DUE TO POTENTIAL FOR MIXED PRECIP THIS EVENING.
COLD FRONT IS MOVING THROUGH THE AREA AT THIS TIME...HOWEVER THE
COLD AIR IS VERY SHALLOW. CURRENT THINKING PRECIP SHOULD BE MOSTLY
SLEET AND/OR SNOW ACROSS CENTRAL AND NORTHEAST MISSOURI AND WEST
CENTRAL ILLINOIS...TRANSITIONING TO RAIN AND FREEZING RAIN WITH
SOME SLEET IN EASTERN MISSOURI AND SOUTHWEST ILLINOIS...WITH
MOSTLY RAIN IN SOUTHEAST MISSOURI AND SOUTH CENTRAL ILLINOIS UNTIL
BETWEEN 10Z-12Z SUNDAY. SOME LINGERING LIGHT WINTRY PRECIPITATION
IS LIKELY AFTER 12Z SUNDAY MORNING...MAINLY SOUTHEAST OF THE
I-44 CORRIDOR IN MISSOURI AND THE I-70 CORRIDOR IN ILLINOIS. LOW
MVFR AND IFR FLIGHT CONDITIONS WILL PREVAIL ONCE THE PRECIP STARTS
AND WILL LIKELY CONTINUE THROUGH MUCH OF THE DAY SUNDAY.
SPECIFICS FOR KSTL...
COLD FRONT IS SOUTH OF LAMBERT AT THIS TIME. NORTHWEST WIND AND
VFR WILL PREVAIL THROUGH MUCH OF THE AFTERNOON...BUT WILL SEE RAIN
MOVE INTO THE TERMINAL FROM THE SOUTH. INITIAL SURGE OF RAIN
SHOULD BE PRETTY LIGHT...BUT WILL SEE RAINFALL INTENSIFY WITH
FLIGHT CONDITIONS DROPPING TO IFR BETWEEN 00Z AND 02Z. EXPECTING
ALL LIQUID PRECIP TO CONTINUE UNTIL LATE EVENING WHEN TEMPERATURE
SHOULD DROP TO FREEZING. PREDOMINANT PRECIP TYPE LOOKS TO BE
FREEZING RAIN AFTER THIS. MAY SEE A LITTLE SLEET OR LIGHT SNOW MIXED
IN BEFORE THE PRECIPITATION ENDS BETWEEN 08Z AND 10Z. LOW MVFR/IFR
FLIGHT CONDITIONS WILL CONTINUE TO PREVAIL IN LIGHT FREEZING
DRIZZLE OR FOG INTO THE DAYLIGHT HOURS OF SUNDAY BEFORE ENDING BY
EARLY TO MID MORNING.
CARNEY
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT CST
TONIGHT FOR AUDRAIN MO-BOONE MO-CALLAWAY MO-COLE MO-
CRAWFORD MO-FRANKLIN MO-GASCONADE MO-KNOX MO-LEWIS MO-
LINCOLN MO-MARION MO-MONITEAU MO-MONROE MO-MONTGOMERY MO-
OSAGE MO-PIKE MO-RALLS MO-SHELBY MO-ST. CHARLES MO-ST.
LOUIS CITY MO-ST. LOUIS MO-WARREN MO.
IL...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT CST
TONIGHT FOR ADAMS IL-BROWN IL-CALHOUN IL-GREENE IL-JERSEY
IL-MACOUPIN IL-PIKE IL.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1037 AM MST SAT JAN 12 2013
.AVIATION...18Z TAFS
AREAS OF -SN AND BLSN WILL CONTINUE TO BRING AREAS OF IFR VSBY INTO
THE AFTERNOON HOURS...THOUGH IMPROVING THROUGH THE DAY. VFR
CONDITIONS ARE EXPECTED AREAWIDE TONIGHT INTO SUNDAY MORNING.
&&
.PREV DISCUSSION... /ISSUED 744 AM MST SAT JAN 12 2013/
UPDATE...ARCTIC AIRMASS IN PLACE ACROSS THE REGION...WITH A DEEP
NEAR SATURATED ISOTHERMAL OVERHEAD PER THE 12Z RAP SOUNDING.
FORECAST MODELS CONTINUE TO PROG LINGERING LARGE SCALE LIFT OVER
THE FA THROUGH THE DAY IN Q-VECTOR ANALYSIS. GIVEN THE DEEP NEAR
SATURATED PROFILES EXPECTED TO REMAIN IN PLACE THROUGH EARLY TO
MID AFTERNOON...HAVE UPDATED THE FORECAST TO MENTION LIGHT SNOW
LIKELY IN THE MORNING...TRENDING TO CHANCE IN THE AFTERNOON FOR
MOST OF THE FA. GIVEN COLD PROFILES OUTSIDE THE DGZ...SMALL CRYSTAL
PRODUCTION FAVORED...SUGGESTING COLUMNS/SMALL PLATES OR VERY LIGHT
SNOWFALL. ALL ELSE IN GOOD SHAPE.
PREV DISCUSSION... /ISSUED 327 AM MST SAT JAN 12 2013/
DISCUSSION...WATER VAPOR SHOWS ELONGATED TROF EXTENDING FROM THE
CA BAJA THROUGH THE NRN PLAINS. AT THE SURFACE...TIGHT PRES GRADS
CONTINUE TO PRODUCE GUSTY NW WINDS ACRS THE CWFA. MAIN LOW CENTER
HAS SHIFTED INTO THE UPPER MIDWEST...ALTHOUGH DEFORMATION ZONE
ACROSS WRN SD CONTINUES TO PRODUCE LIGHT SNOW ACROSS OUR AREA.
WIND CHILLS HAVE DROPPED TO 15 BELOW TO 30 BELOW ZERO.
TODAY...WEAK LIFT WILL CONTINUE TO PRODUCE SOME LIGHT SNOW ACROSS
THE CWFA THIS MORNING ALTHOUGH ANY ADDITIONAL ACCUMULATIONS WILL
REMAIN LESS THAN AN INCH. HOWEVER...WINDS GUSTING TO AROUND 40 MPH
WILL CONTINUE TO PRODUCE AREAS OF BLOWING SNOW ESPECIALLY ON THE
SD PLAINS THIS MORNING...ALONG WITH WIND CHILLS TO 30 BELOW. HAVE
DOWNGRADED THE WINTER STORM WARNING OVER PORTIONS OF WRN SD GIVEN
THE DIMINISHING SNOW...AND WILL CARRY WINTER WX ADVISORIES FOR THE
ENTIRE CWFA THROUGH THE MORNING GIVEN COMBINATION OF BLOWING SNOW
AND WIND CHILLS. CONDITIONS WILL IMPROVE THIS AFTERNOON AS WINDS
RELAX.
TONIGHT THROUGH MONDAY NIGHT...UPPER TROF AXIS WILL SHIFT ONLY
SLIGHTLY EWD INTO EARLY NEXT WEEK...WITH SURFACE RIDGE DOMINATE
OVER THE NRN PLAINS. THIS WILL LEAD TO ONLY A SLOW RISE IN
TEMPS...WITH SNOW COVERED AREAS REMAINING SEVERAL DEGREES BELOW
GUIDANCE. GENERALLY DRY CONDITIONS EXPECTED...ALTHOUGH A FEW SNOW
SHOWERS POSSIBLE IN THE NRN BLKHLS SUNDAY AS A WEAK SHORT WAVE
CROSSES THE REGION.
EXTENDED...WARM FRONT PUSHES OVER THE REGION TUESDAY...WITH BROAD
AREA OF ISENTROPIC LIFT DEVELOPING MAINLY OVER THE WRN CWA.
THEREFORE...WILL KEEP PRECIP CHANCES OVER THIS AREA THRU THE DAY
WITH CHANCES DIMINISHING OVERNIGHT. SOME PRECIP OVERNIGHT MAY BE
FREEZING RAIN AS WARM AIR ALOFT CONTINUES TO SLIDE IN...SO WILL HAVE
TO KEEP AN EYE ON THIS. FOR THE REMAINDER OF THE WEEK...
WEST/NORTHWEST FLOW ALOFT SETS UP OVER THE AREA BRINGING NEAR
TO SLIGHTLY ABOVE AVERAGE TEMPERATURES AND DRY CONDITIONS.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.
&&
$$
SHORT TERM...WFO UNR
LONG TERM....WFO UNR
AVIATION...13
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
240 PM CST SAT JAN 12 2013
.SHORT TERM...TONIGHT THROUGH TUESDAY
240 PM CST SAT JAN 12 2013
THE MAIN FOCUS IN THE SHORT TERM IS WITH THE SNOW POTENTIAL
TONIGHT ACROSS FAR SOUTHWEST WISCONSIN AND NORTHEAST IOWA ALONG
WITH TEMPERATURES INTO EARLY NEXT WEEK.
CURRENTLY...AN UPPER LEVEL TROUGH IS DIGGING SOUTH ACROSS THE
PLAINS WHILE A RIDGE OF HIGH PRESSURE BECOMES MORE AMPLIFIED
ACROSS THE EAST COAST. AT THE SURFACE...COLDER AIR IS DROPPING
DOWN FROM CENTRAL CANADA DOWN THROUGH THE PLAINS ON THE BACK SIDE
OF A LOW THAT IS MOVING INTO WESTERN QUEBEC. AN INVERTED TROUGH
EXTENDS TO THE SOUTHWEST OUT OF THIS LOW AND HAS HELPED TO POOL
SOME HIGHER LOW LEVEL HUMIDITY THAT HAPPENS TO BE IN THE -8C TO
-12C RANGE...WHICH INTRODUCES ICE INTO THE CLOUD LAYER. OVERALL
FORCING IS WEAK BUT ENOUGH FROM THE SURFACE TROUGH TO PRODUCE SNOW
SHOWERS AND FLURRIES ACROSS THE REGION.
12.12Z NAM/GFS AND 12.18Z RAP SOUNDINGS SHOW THE THIN LOW LEVEL
CLOUD LAYER STICKING AROUND OVERNIGHT INTO TOMORROW AND DEEPENING
AS A LOW PRESSURE SYSTEM TRACKS TO THE NORTHEAST FROM THE SOUTHERN
PLAINS ON INTO MICHIGAN TONIGHT. THE QUESTION WITH THIS SYSTEM HAS
BEEN HOW FAR WEST THE SNOW WOULD MAKE IT. THE PREVIOUS RUNS OF THE
ECMWF HAD BEEN THE FURTHEST WEST OVER THE PAST FEW DAYS...BUT NOW
HAS COME INTO A CONSENSUS WITH WHAT THE 12.12Z NAM/GFS/GEM ARE
SHOWING WITH THE TRACK FURTHER TO THE EAST WITH JUST A BRIEF
PERIOD OF LIGHT SNOW OCCURRING ACROSS NORTHEAST IOWA AND FAR
SOUTHWEST WISCONSIN. 12.12Z NAM/GFS AND 12.18Z RAP CROSS SECTIONS
SHOWS AN ASCENDING BAND OF FRONTOGENESIS THAT IS CLOSER TO THE
SURFACE TO THE SOUTHEAST AND MORE OF A MID LEVEL CIRCULATION
ACROSS THE REST OF THE FORECAST AREA. THIS FORCING SHOULD BE
ENOUGH TO AT LEAST PRODUCE SOME FLURRIES...BUT CAN NOT COMPLETELY
RULE OUT THAT SOME SNOW COULD MAKE IT FURTHER WEST DEPENDING ON
HOW STRONG THE CIRCULATION GETS. THE SNOW WILL DEVELOP NORTHWARD
THIS EVENING BEFORE QUICKLY GETTING SHUNTED OFF TO THE EAST BY DAY
BREAK. ACCUMULATIONS ARE EXPECTED TO BE ON THE LIGHT SIDE AT LESS
THAN AN INCH ACROSS GRANT COUNTY.
AFTER THIS SYSTEM MOVES THROUGH...THE COLD AIR WILL MOVE IN ACROSS
THE REGION FROM THE NORTHWEST AND LINGER INTO THE EARLY PART OF
NEXT WEEK. HOW FAR TEMPERATURES ARE ABLE TO DROP IS OF QUESTION
RIGHT NOW SINCE MOST OF THE AREAS SNOW PACK HAS ERODED DUE TO THE
FOG...WIND...RAIN AND WARM AIR THAT WAS AROUND EARLIER THIS WEEK.
HAVE NOT MADE MANY ADJUSTMENTS TO THE GOING FORECAST WITH SUNDAY
LOOKING LIKE THE COLDEST DAY OVER THE NEXT WEEK.
.LONG TERM...TUESDAY NIGHT THROUGH SATURDAY
240 PM CST SAT JAN 12 2013
THE NEXT CHANCE FOR SNOW COMES IN TUESDAY NIGHT INTO WEDNESDAY AS
A MID LEVEL SHORT WAVE TROUGH DIVES DOWN FROM NORTHWEST CANADA
DOWN INTO THE UPPER MISSISSIPPI RIVER VALLEY. THERE ARE SOME
DIFFERENCES BETWEEN THE LONG TERM GUIDANCE WITH THIS SYSTEM WITH
THE 12.12Z GFS SHOWING A MUCH MORE COMPACT TROUGH THAT COMES
THROUGH FASTER THAN WHAT THE 12.12Z ECMWF IS ADVERTISING. THIS
LEADS TO A DEEPER SURFACE LOW THAT DIVES FURTHER SOUTH ON THE GFS
COMPARED TO THE ECMWF AS WELL. BECAUSE OF THESE DIFFERENCES...HAVE
NOT HIT THE PRECIPITATION CHANCES TO HIGH YET...BUT OVERALL THE
BETTER CHANCES FOR SEEING THE SNOW WILL BE ACROSS THE NORTHERN
PORTION OF THE FORECAST AREA. WITH THERE NOT BEING MUCH OF A SHIFT
IN THE UPPER LEVEL PATTERN...THERE COULD BE A FEW MORE CHANCES OF
LIGHT SNOW NEXT WEEK BUT MUCH OF THE FORCING APPEARS TO BE GOING
JUST NORTH OF THE REGION. WITH THE PATTERN NOT SHIFTING
MUCH...TEMPERATURES WILL NOT VARY MUCH EITHER AND REMAIN FAIRLY
SEASONAL.
&&
.AVIATION...THROUGH 18Z SUNDAY
1142 AM CST SAT JAN 12 2013
DEEP LOW PRESSURE WILL WEAKEN AND CONTINUE MOVING FARTHER EAST
INTO ONTARIO. WITH LINGERING CYCLONIC FLOW AND COLD AIR ADVECTION
ACROSS THE AREA...PLAN ON MVFR CLOUDS ALONG WITH SCATTERED FLURRY
ACTIVITY TO CONTINUE INTO THIS EVENING. EXPECTING WINDS TO SUBSIDE
THROUGH THE DAY AS PRESSURE GRADIENT BECOMES MORE RELAXED.
ANOTHER WEAKER WAVE OF LOW PRESSURE WILL THEN RIPPLE NORTHEAST
FROM THE SOUTHERN PLAINS INTO THE GREAT LAKES REGION TONIGHT
THROUGH SUNDAY MORNING. WITH THIS TRACK...EXPECTING ANY
ACCUMULATING SNOW TO REMAIN SOUTH OF THE AREA. BUFKIT SOUNDING
DATA CONTINUES TO SHOW MVFR CLOUD COVER AND FLURRIES LINGERING THROUGH
18Z SUNDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
240 PM CST SAT JAN 12 2013
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...HALBACH
LONG TERM...HALBACH
AVIATION...DAS