Forecast Discussions mentioning any of
"HRRR" "RR" "RUC13" "RUC" received at GSD on 01/19/12
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
824 PM MST WED JAN 18 2012
.UPDATE...
&&
.SHORT TERM...HRRR DID A GOOD JOB WITH WINDS LAST NIGHT AND SO FAR
IS DOING WELL THIS EVENING. IT SHOWS WINDS MAY DECREASE SOME THE
NEXT FEW HOURS AND THEN PICK UP AGAIN FM 09Z-12Z BEFORE DECREASING
AGAIN. SO FAR THE HIGHEST GUSTS HAVE BEEN IN THE TYPICAL WINDY
AREAS OVER BOULDER AND JEFFERSON COUNTIES AND IT MAY STAY THAT WAY
OVERNIGHT. IN THE MOUNTAINS THE HIGH WIND WARNING WAS REPLACED BY
A BLIZZARD WARNING HOWEVER AT THIS TIME IT LOOKS LIKE MOST OF THE
SNOW WILL NOT OCCUR UNTIL AFTER MIDNIGHT WITH THE WORST CONDITIONS
ALONG AND NORTH OF I-70.
.AVIATION...WINDS AT DIA HAVE BEEN A NIGHTMARE THIS EVENING AS
DIRECTIONS HAVE BEEN ALL OVER THE PLACE WITH LLWS SENSORS SHOWING
MULTIPLE DIRECTIONS AT THE SAME TIME. LATEST HRRR KEEPS DIRECTIONS
BASICALLY ALL OVER THE PLACE THRU AT LEAST 12Z WHILE THE RUC HAD
WINDS BECOMING MORE WNW AFTER MIDNIGHT AND STAYING THAT WAY THRU
12Z. OVERALL CONFIDENCE IS NOT VERY HIGH WITH WIND FCST THRU 12Z
HOWEVER HRRR MAY END BEING THE RIGHT SOLUTION IN THE END WITH
VARIABLE DIRECTIONS THE ENTIRE NIGHT.
&&
.PREV DISCUSSION... /ISSUED 234 PM MST WED JAN 18 2012/
SHORT TERM...MAIN CONCERN IS STILL IN THE HIGH WIND EVENT GIVEN
THE VERY FAST NORTHWEST FLOW FOR TONIGHT AND THURSDAY. THIS IS
STILL NOT A CLEAR CUT EVENT ESPECIALLY GIVEN THE SNOW POTENTIAL
FOR THE MOUNTAINS AND LACK OF CURRENT HIGH WINDS IN THE FOOTHILLS
AND ADJACENT PLAINS. AS EXPECTED IN THIS PORTION OF THE EVENT
THERE IS STILL A LOT OF VERTICAL SHEAR WHICH IS NOT ALLOWING AN
AMPLIFIED MOUNTAIN WAVE TO DEVELOP. THE SHEAR PROFILE IS STILL
EXPECTED TO IMPROVE BY THIS EVENING AS THE MAIN JET CORE CONTINUES
TO MOVE AWAY FROM COLORADO. CROSS SECTIONS STILL SHOWING THE
STRONGER WINDS DESCENDING LEE SLOPES DURING THE EVENING WITH
60-80KT OF CROSS BARRIER FLOW.
THE MAIN CHANGE IN THE FORECAST IS TO UPGRADE THE HIGH WIND
WARNING TO A BLIZZARD WARNING FOR ZONES 33 AND 34 FROM THIS
EVENING THROUGH THURSDAY MORNING. THERE WILL BE SOME LIGHT SNOW
MOVING IN THIS EVENING GIVEN CURRENT SNOW OCCURING OVER IDAHO THIS
AFTERNOON. COUPLED WITH THE SNOW AND WINDS SHOULD BE ABLE TO
PRODUCE BLIZZARD CONDITIONS. NOW FOR ZONE 31 HAVE GONE WITH A
WINTER STORM WARNING STARTING LATER THIS EVENING AS THE OROGRAPHIC
FLOW AND BETTER LAPSE RATES SHOULD PRODUCE BETTER SNOW PRODUCTION
WITH NOT AS MUCH WIND. THE LOW LAPSE RATES OF 2-4C/KM ACROSS ZONE
33 AND 34 WILL RESULT IN MUCH LOWER SNOWFALL AND WOULD LIKE TO HIT
THE WIND HARDER THAN THE SNOW.
THE CURRENT HIGH WIND WARNING FOR ZONE 38 AND 39 MAY BE THE MOST
SUSPECT DESPITE IMPROVING WAVE AMPLIFICATION TNT. THE INCREASE
MOISTURE ALONG THE DIVIDE MAY END UP SHOWING SOME DEAMPLIFICATION
OF THE WAVE RESULTING IN LESS WIND AT THE BASE OF THE FOOTHILLS.
REGARDLESS...TOO CLOSE TO CALL IN TERMS OF MAKING ANY CHANGES AND
WILL LET THE WARNING PLAY OUT GIVEN THE VERY FAST MOUNTAIN TOP
FLOW.
LONG TERM...PACIFIC MOISTURE WILL CONTINUE TO STREAM INTO
COLORADO THURSDAY NIGHT AS A SHORTWAVE MOVES IN FROM THE PACIFIC
NORTHWEST TO FLATTEN THE SLIGHT RIDGING ALOFT. SNOW WILL BE HEAVY
OVER THE HIGHER MOUNTAINS AT TIMES THROUGH THE NIGHT AND INTO
FRIDAY...AS COLD ADVECTION WILL MOVE IN BEHIND THE SHORTWAVE. THE
SNOW WILL FAVOR ZONE 31 THE BEST AND TO A LESSER EXTENT ZONE 33.
WILL CONTINUE THE WINTER STORM WARNING FOR ZONE 31 THROUGH THE
AFTERNOON ON FRIDAY AS ANOTHER 8 TO 12 INCHES OF SNOW ARE EXPECTED
TO FALL FROM THURSDAY EVENING THROUGH FRIDAY AFTERNOON...BRINGING
THE TOTAL SNOWFALL EXPECTED TO 1 TO 2 FEET. THE OTHER HIGHER
MOUNTAINS SHOULD SEE ANOTHER 3 TO 8 INCHES WITH THE HIGHER AMOUNTS
NEAR ROCKY MOUNTAIN NATIONAL PARK. WITH RELATIVELY STRONG WINDS
STILL OCCURRING THURSDAY NIGHT...SHOULD STILL SEE AREAS OF
BLOWING SNOW REDUCING VISIBILITIES ESPECIALLY OVER PASSES THAT
NIGHT. WINDS WILL BE SLIGHTLY DIMINISHING BEGINNING FRIDAY. AFTER
A SHORT BREAK FRIDAY NIGHT INTO EARLY SATURDAY MORNING IN SNOWFALL
FOR THE MOUNTAINS AS ANOTHER SHORTWAVE RIDGE BUILDS IN...ANOTHER
PACIFIC SHORTWAVE TROUGH WITH A MORE ZONAL JET AHEAD OF IT WILL
PUSH MORE MOISTURE OVER THE MOUNTAINS FOR MORE SNOW AND COOLER
TEMPERATURES SATURDAY THROUGH SUNDAY NIGHT. LOOKING FURTHER AHEAD
FOR THE MOUNTAINS...ANOTHER SHORTWAVE WILL OCCUR MONDAY MORNING
BEFORE ANOTHER TROUGH...THIS TIME LOOKING DEEPER WILL BRING MORE
SNOW THROUGH MID NEXT WEEK. MODELS ARE TRYING TO GET A HANDLE ON
THE DEPTH AND SPEED...BUT OVERALL PATTERN LOOKS AGREEABLE.
DEFINITELY A MORE ACTIVE PATTERN FOR THE MOUNTAINS.
SWITCHING NOW TO THE LOWER FOOTHILLS AND PLAINS...THURSDAY NIGHT
WILL CONTINUE THE DROP IN WINDSPEEDS BUT WILL STILL SEE GUSTS UP
TO 50 MPH AT TIMES IN AND NEAR THE FOOTHILLS. SOME BLOWOVER SNOW
MAY BRING LIGHT SNOW AND AREAS OF BLOWING SNOW TO THE HIGHER
FOOTHILLS BUT AMOUNTS WILL BE LIGHT. WARM ADVECTION THAT NIGHT
WILL KEEP MINIMUM TEMPERATURES MODERATED ESPECIALLY OVER THE
PLAINS. FRIDAY WILL BE SLIGHTLY COOLER THAN THURSDAY AS THE
SHORTWAVE TROUGH PASSES OVER BUT STILL WARMER THAN NORMAL. THERE
IS A VERY SLIGHT CHANCE FOR A SHOWER OR TWO AS THE COLD FRONT
MOVES OVER HEAD...BUT CHANCE WAS SO SMALL DECIDED TO LEAVE OUT OF
FORECAST. SATURDAY AND SUNDAY WILL REMAIN WARMER THAN NORMAL WITH
ONLY A SLIGHT CHANCE OF SHOWERS OVER THE FOOTHILLS. THE NEXT
SYSTEM MOVING IN MONDAY WILL BRING COOLER MORE SEASONAL
TEMPERATURES WITH A SLIGHT CHANCE OF SHOWERS THROUGH TUESDAY. THE
ECMWF HAS A MUCH GREATER CHANCE FOR PRECIP THAN THE GFS AS IT DIGS
THE TROUGH DEEPER. WILL STAY WITH A SLIGHT CHANCE FOR NOW.
AVIATION...SURACE WIND FORECAST REMAINS QUITE THE CHALLENGE WITH
MAINLY E-SE WINDS AT DEN AND APA AT THE CURRENT TIME. STARTING TO
SEE A MORE WESTERLY COMPONENT AT BJC AND THIS SHOULD INCREASE
SHARPLY THIS EVENING WITH GUSTS UP TO 50KT POSSIBLE. WOULD EXPECT
APA AND DEN TO EVENTUALLY SHIFT TO SOME SORT OF W-SW COMPONENT BY
LATER THIS AFTERNOON AND EVENING.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL NOON MST THURSDAY FOR COZ035-036-038-039.
BLIZZARD WARNING UNTIL NOON MST THURSDAY FOR COZ033-034.
WINTER STORM WARNING UNTIL 5 PM MST FRIDAY FOR COZ031.
&&
$$
SHORT TERM...RPK
LONG TERM....KRIEDERMAN
AVIATION...RPK
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
711 PM MST WED JAN 18 2012
.UPDATE...
THE DEEPER MOISTURE PLUME REMAINS NORTH OF COLORADO BUT EXPECTED
TO SAG SOUTHWARD LATER THIS EVENING. SNOW HAS NOT STARTED OVER THE
WEST SIDE OF THE DIVIDE JUST YET...BUT MODELS INDICATE SNOW WILL
BE EXPANDING SOUTHWARD OVER THE NRN DIVIDE AND NEAR VAIL PASS
BETWEEN 8 PM AND 11 PM THIS EVENING. A LITTLE CONCERNED THAT WEST
SOUTHWEST FLOW AT MOUNTAIN TOP MAY SHELTER VAIL PASS AND SNOW MAY
BE HARD PRESS TO DEVELOP THERE. THE LATEST HRRR MODEL KEPT THE
SNOW EAST OF VAIL PASS. WILL SEE WHAT EVOLVES DURING THE NEXT 3 TO
6 HOURS.
&&
.PREV DISCUSSION /ISSUED 323 PM MST WED JAN 18 2012/...
SHORT TERM /TONIGHT THROUGH FRIDAY/...
THE PACIFIC MOISTURE TAP HAS OPENED UP...EXTENDING FROM THE PACIFIC
NORTHWEST BACK TO HAWAII AND BEYOND ON WATER VAPOR SATELLITE IMAGES.
A SERIES OF SHORTWAVE TROUGHS ACROSS THE NORTHERN PACIFIC OCEAN WILL
TAP THIS MOISTURE AS THEY MOVE INLAND ACROSS THE NORTHERN AND CENTRAL
ROCKIES IN THE DAYS AHEAD.
THE FIRST SHORTWAVE WAS MOVING ACROSS OREGON/WASHINGTON BUT WILL GET
STRETCHED AND WEAKEN BY THE TIME IT ZIPS ACROSS THE NORTH TONIGHT.
REGIONAL RADAR SHOWING PRECIP ACROSS SRN ID/NRN NV/NW UT...AND THIS
DEEPER MOISTURE IS EXPECTED TO STEADILY ADVANCE INTO NE UT/WRN CO
TONIGHT CAUSING SNOW TO INCREASE ACROSS THE NORTHERN AND CENTRAL
MTNS. THIS COUPLED WITH STRONG WINDS WILL PRODUCE HAZARDOUS WINTER
CONDITIONS IN THE ELKHEAD/PARK/GORE/FLATTOP/ELK MTNS TONIGHT INTO
THU MORNING. MAIN FORCING LOOKS TO BE WARM ADVECTION AND PERSISTENT
AND MOIST WESTERLY OROGRAPHIC FLOW SLAMMING INTO THE MTNS. MODELS
INDICATE 700 MB /ROUGHLY 10K FEET ELEVATION/ WESTERLY WINDS IN THE
40-55 KT RANGE NORTH OF I-70. LOOKS LIKE A DOWNTURN IN SNOW ACTIVITY
LATER BY THU AFTERNOON IN BETWEEN SHORTWAVES...WITH THE NEXT AND
STRONGER WAVE AFFECTING THE FORECAST AREA THU NIGHT INTO FRI. IF
CURRENT MODELS ARE CORRECT...SNOW COULD LAST LONGER INTO FRI THAN
CURRENT WINTER HIGHLIGHT SUGGEST. BUT...WITH TIMING OFTEN
PROBLEMATIC IN THESE FAST ZONAL FLOW REGIMES...WILL NOT DO ANY
ADJUSTING AT THIS TIME. THE EASTERN UINTA MTNS ARE EXPECTED TO
GENERALLY BE SHADOWED BY THE HIGHER MTNS TO THEIR WEST WITH ONLY
SOME LIGHT ACCUMULATIONS.
ADDED A BLIZZARD WARNING FOR CO ZONE 10 /GORE AND ELK MTNS/ TO
THE MIX OF WINTER HIGHLIGHTS FOR THE NORTHERN CO MTNS TONIGHT AND
THU MORNING. MOST CONCERNED ABOUT VAIL PASS AND SURROUNDING AREAS
WHERE BLOWING SNOW AND STRONG WINDS SHOULD POSE A SIGNIFICANT
DANGER TO TRAVEL OVER I-70 TONIGHT. LOWER AND MORE WESTERN VALLEY
AREAS OF ZONE 10 NOT LIKELY TO BE AS AFFECTED. THANKS FOR THE
COORDINATION WFO BOU AND PUB.
THERE IS OVERLAP OF PRODUCTS AT THIS TIME BUT EXPECT THE WIND
HIGHLIGHTS TO BE CANCELLED AS THE SNOW/BLIZZARD HIGHLIGHTS GO
INTO EFFECT THIS EVENING.
AN AREA THAT BEARS WATCHING IS THE STEAMBOAT VALLEY. NAM FORECAST
SOUNDINGS HAVE THE LOWER ATMOSPHERE BECOMING NEARLY SATURATED AND
ISOTHERMAL IN THE LOWER END OF THE FAVORABLE SNOW GROWTH REGIME FOR
A TIME TONIGHT...OFTEN FAVORABLE FOR ENHANCED SNOW PRODUCTION.
RAISED POPS TO LIKELY TONIGHT AND ADDED A COUPLE INCHES OF
ACCUMULATION FOR THE VALLEY FROM ABOUT HAYDEN EAST TO STEAMBOAT.
STEAMBOAT VALLEY COULD SEE ACCUMULATING SNOW AGAIN THU NIGHT/FRI
MORNING.
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
ACTIVE PATTERN WILL CONTINUE AS THE MOIST AND ENERGETIC FLOW OVER
THE REGION PERSISTS THROUGH THE LONG TERM PERIOD. A COUPLE OF
SHORTWAVE TROUGHS WILL MOVE ACROSS THE WESTERN CONUS BEGINNING ON
SATURDAY. EACH WAVE WILL BRING A ROUND OF SNOW...ESPECIALLY FOR
THE MOUNTAINS...AS IT SWEEPS OVER EASTERN UTAH AND WESTERN
COLORADO. THE NORTH WILL GENERALLY BE FAVORED. DUE TO THE FAST
PACIFIC FLOW FEEL THAT MODEL TIMING WILL CONTINUE TO EVOLVE
SOMEWHAT...BUT IN GENERAL MODELS SHOW EXCELLENT AGREEMENT.
THE PERIOD BEGINS IN A LULL AS A FLAT SHORTWAVE RIDGE PASSES
FRIDAY NIGHT. THEN PRECIPITATION WILL SPREAD IN ON SATURDAY AS
THIS PERIOD/S FIRST TROUGH APPROACHES AND MOVES OVERHEAD SAT NIGHT.
THE PATTERN BECOMES MORE AMPLIFIED BUT STILL PROGRESSIVE AS THIS
TROUGH DIGS INTO THE CENTRAL CONUS...AND A RIDGE FOLLOWS ACROSS
THE WEST. SNOW WILL GRADUALLY WIND DOWN ON SUN/SUN NIGHT AS THE
RIDGE AXIS PASSES OVERHEAD. THE NEXT WAVE APPROACHES ON MONDAY
WITH THE TROUGH AXIS REACHING WESTERN COLORADO MONDAY EVENING.
AGAIN MODEL CONSISTENCY QUITE HIGH. AFTER THIS WAVE MODELS
INDICATE A LESS PROGRESSIVE FLOW AS HIGH PRESSURE BUILDS OFF THE
SOUTHERN CALIFORNIA COAST...AND LOW PRESSURE OVER THE GREAT LAKES
TO THE SOUTHERN PLAINS. NORTHWEST FLOW WILL DEVELOP OVER OUR AREA
AND PERSIST THROUGH THE END OF THE PERIOD. EXPECT THAT THE
NORTHERN DIVIDE AREA WILL CONTINUE TO SEE SNOW SHOWERS AT TIMES IN
THIS FAVORABLE NORTHWEST FLOW.
AVIATION /FOR 00Z TAF ISSUANCE/...
VFR CONDITIONS EXPECTED AT ALL TAF SITES THROUGH INTO EVENING.
CIGS WILL CONTINUE TO LOWER FOR AREAS NORTH OF I-70...AND ALONG
THE CENTRAL MOUNTAINS LATE THROUGH THIS EVENING. AREAS OF -SN AND
BLSN WILL DEVELOP...MAINLY ALONG THE CONTINENTAL DIVIDE IN THE
VAIL VICINITY AND NORTHWARD...AND WILL RESULT IN MVFR TO AREAS OF
IFR CEILINGS AND VISIBILITIES. STRONG WINDS WILL CONTINUE THROUGH
THURSDAY MORNING OVER THE MOUNTAINS ABOVE THE 10000 FOOT LEVEL.
WEST WINDS RANGING FROM 40 TO 60 MPH WITH GUSTS TO 75 MPH OR EVEN
STRONGER WILL RESULT IN SIGNIFICANT MECHANICAL TURBULENCE THROUGH
THURSDAY AFTERNOON.
SNOWFALL WILL GRADUALLY INCREASE MAINLY OVER THE MOUNTAINS AFTER
01Z THIS EVENING AND PERSIST AT LEAST INTO EARLY FRIDAY...WITH THE
GREATEST AREA OF LOW CEILINGS AND VISIBILITIES EXPECTED OVER THE
MOUNTAINS NORTH OF I-70. THE VALLEY TAF SITES WILL GENERALLY
REMAIN VFR THROUGH THURSDAY...WITH A FEW SNOW SHOWERS POSSIBLE FOR
KEGE.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...HIGH WIND WARNING UNTIL NOON MST THURSDAY FOR ZONE 012.
WIND ADVISORY UNTIL NOON MST THURSDAY FOR ZONES 018-019.
WINTER STORM WARNING UNTIL 9 AM MST FRIDAY FOR ZONE 004.
BLIZZARD WARNING UNTIL NOON MST THURSDAY FOR ZONE 010.
WINTER WEATHER ADVISORY UNTIL 9 AM MST FRIDAY FOR ZONE 013.
UT...NONE.
&&
$$
UPDATE.......PF
SHORT TERM...JAD
LONG TERM....EH
AVIATION.....EH
AREA FORECAST DISCUSSION
NWS DENVER CO
1043 PM MST MON JAN 16 2012
.UPDATE...THE AREA OF SNOWFALL HAS REGENERATED A BIT...POSSIBLY
ASSOCIATED WITH BOUNDARY LAYER CONVERGENCE. ANTICYCLONE CENTERED
NORTH OF FORT COLLINS HAS RESULTED IN SHALLOW EAST/NORTHEAST FLOW
INTERACTING WITH WEST/NORTHWEST FLOW OFF THE FOOTHILLS. WE WILL
HAVE TO DELAY THE DEPARTURE OF SNOW A COUPLE MORE HOURS TO ACCOUNT
FOR THIS.
&&
.AVIATION...SNOW HAD REDEVELOPED AT KDEN AND KAPA...AND WILL HAVE
TO EXTEND THE SNOW THERE A COUPLE MORE HOURS BASED ON LATEST RADAR
TRENDS. COULD SEE ANOTHER QUARTER INCH OR SO.
&&
.PREV DISCUSSION... /ISSUED 910 PM MST MON JAN 16 2012/
UPDATE...SNOW IS DECREASING RATHER QUICKLY AND PRETTY MUCH ON
TRACK. ONE BAND OF SNOW STILL LINGERED FROM FORT COLLINS TO
DIA...WITH ANOTHER STRETCHING FROM THE PALMER DIVIDE THROUGH EAST
CENTRAL COLORADO. MOUNTAIN AREAS HAVE ALSO SEEN SNOW DECREASE
SHARPLY LATE THIS EVENING. OVERALL FORECAST IS ON TRACK WITH SNOW
ENDING BY/SHORTLY AFTER MIDNIGHT WITH CLEARING SKIES AND COLD
TEMPERATURES OVERNIGHT.
AVIATION...SNOW IS DECREASING SO CURRENT TRENDS INDICATE SNOW
WILL BE ALL BUT GONE AT KDEN BY 06Z. KAPA AND KBJC SHOULD SEE
FLURRIES WRAP UP IN THE NEXT HOUR. THEN CEILINGS WILL GRADUALLY
LIFT AND BREAK UP BETWEEN 06Z AND 09Z.
PREV DISCUSSION... /ISSUED 453 PM MST MON JAN 16 2012/
UPDATE...LATEST RADAR SHOWS A GOOD BAND OF SNOW ASSOCIATED WITH
UPPER TROUGH AND MID LEVEL COLD FRONT SPREADING OFF THE FOOTHILLS.
WE HAVE INCREASED SNOW CHANCES FOR DENVER METRO AREA AND NORTHEAST
ACROSS THE PLAINS DUE TO THIS FEATURE...AND SHALLOW UPSLOPE
SLOWING DISSIPATION OF THE BAND IN MEAN WESTERLY FLOW ALOFT.
AVIATION...CURRENT FORECAST IS ON TRACK WITH SHOWERS SPREADING
SOUTHEAST ACROSS THE FRONT RANGE AIRPORTS FROM NOW TIL 04Z.
VISIBILITIES COULD DROP TO 1/2 MILE AND BRIEFLY 1/4 MILE IN THE
HEAVIEST SHOWERS PER UPSTREAM OBS FROM KCYS AND FORT COLLINS
SPOTTER REPORTS...SO HAVE LOWERED THE TEMPO VSBYS IN TAFS.
PREV DISCUSSION... /ISSUED 335 PM MST MON JAN 16 2012/
SHORT TERM...WIDE BAROCLINIC ZONE ASSOCIATED WITH THE UPPER TROUGH
AND SFC COLD FRONT PASSING OVER THE MOUNTAINS AT THIS HOUR. FRONTAL
BNDRY HAS MOVED THROUGH JACKSON COUNTY AS NOTED BY A SUDDEN DROP IN
TEMPERATURE AND ABRUPT SHIFT TO NORTHWEST WINDS AT WALDEN WHERE THE
TEMPERATURE FELL 11 DEGS F IN LESS THAN AN HOUR. BANDED SLANTWISE
CONVECTION...I.E. SNOWFALL...STREAKING CROSSING THE HIGH COUNTRY
JUST AHEAD OF THE 700-500MB TROUGH AXIS. HAVE NOTICED A STEADY
INCREASE IN SNOW INTENSITY AND COVERAGE IN THE PAST COUPLE OF HOURS
WITH RUC QG VERTICAL FIELDS INDICATING WEAK TO MODERATE LARGE SCALE
ASCENT CENTERED OVER THE NRN MTNS. WHERE THIS PRECIP GOES FROM HERE
AND HOW EXTENSIVE IT WILL BE DEPENDS ON WHICH MODEL YOU LOOK AT.
BOTTOM LINE...THE NAM IS DRIER AND A BIT SLOWER WITH ITS EASTWARD
PROGRESS THAN THE GFS...ECMWF AND SREF. WHEREAS...THE GFS AND SREF
SHOW A WIDER AREA OF PRECIPITATION/SNOW FIELD ACROSS NERN COLORADO
THIS EVENING...WITH A COUPLE INCHES OF SNOW ACCUM BY MIDNIGHT
ACROSS THE NORTHEAST CORNER OF THE STATE. OVERALL SEE BANDED PRECIP
TRANSLATING SOUTHWARD ACROSS THE NERN PLAINS THIS EVENING...WITH THE
BACK EDGE OF THIS PRECIP SOUTHEAST OF THE DENVER METRO AREA BY
AROUND 05Z..AND OUT OF THE CWFA (LINCOLN COUNTY) POSSIBLY BY 08Z OR
09Z TONIGHT. EXPECTED SNOW ACCUMULATION WITHIN THE I-25 URBAN
CORRIDOR MINIMAL AT BEST...PERHAPS A HALF INCH ON GRASSY SURFACES
FROM ONE OF THE HEAVIER SNOW BANDS COMING OFF THE FOOTHILLS EARLY
THIS EVENING. AGAIN...APPEARS THE NORTHEAST CORNER IN THE BEST
POSITION TO SEE ACCUMULATING SNOWFALL THIS EVENING.
LATER TONIGHT...SHOULD SEE GUSTY NORTHWEST WINDS USHERING IN DRIER
AND COLDER AIR FROM WYOMING. CLEARING LATE WILL ALLOW FOR STRONG
RADIATIONAL COOLING CAUSING TEMPERATURES TO PLUNGE WELL BELOW ZERO
IN THE HIGH MOUNTAIN VALLEYS. MIN TEMPERATURES ALSO QUITE COLD ON
THE PLAINS WITH SINGLE DIGITS ABOVE ZERO THE NORM BY MORNING LIGHT.
COULD SEE A FEW SUBZERO READINGS IN LOW LYING AREAS SUCH AS ALONG
THE SOUTH PLATTE RIVER.
ON TUESDAY...SWIFT NORTHWEST FLOW ALOFT CONTINUES OVER THE STATE
WITH A DRIER AIRMASS UPSTREAM. ANY SNOWFALL TOMORROW WILL BE
CONFINED TO THE HIGHEST PEAKS AND WEST FACING SLOPES ALONG THE
DIVIDE. EVEN THERE SNOW INTENSITIES WILL BE WEAK. TEMPERATURES WILL
STRUGGLE TO WARM TOMORROW WITH ONGOING COLD AIR ADVECTION. SEE
LITTLE CLOUD COVER ESPECIALLY EAST OF THE MTNS WITHE FLOW
REGIME.
LONG TERM...MAIN CONCERN FOR THE UPCOMING WEEK WILL BE THE HIGH
WIND POTENTIAL IN THE MOUNTAINS...FOOTHILLS AND ADJACENT PLAINS AND
DEVELOPING SNOW IN THE MOUNTAINS BY MIDWEEK. MOST OF THE WESTERN
U.S. WILL TRANSITION TO A STRONG AND ZONAL WEST TO NORTHWEST FLOW
ALOFT THIS WEEK. IT APPEARS THE STRONGEST WINDS WILL EFFECT THE
REGION LATE TUE NIGHT THROUGH EARLY THURSDAY AM AS A STRONG
130-150KT JET CORE LIFTS OUT ACROSS WYOMING ON WEDNESDAY. THE
SURFACE PRESSURE GRADIENT WILL TIGHTEN TO 10-15 MB ACROSS THE STATE
ON WED WHILE MOUNTAIN TOP STABILITY INCREASES. CROSS SECTIONS SHOW
AMPLIFIED MOUNTAIN WAVE DEVELOPING WITH 60-80KT OF CROSS BARRIER
FLOW. STILL A LOT OF QUESTION MARKS AS THERE ARE SOME CONFLICTING
PARAMETERS. THERE IS A LOT OF VERTICAL SHEAR ESPECIALLY EARLY ON
WEDNESDAY FOR AN AMPLIFIED MOUNTAIN WAVE. SHEAR PROFILE IMPROVES A
BIT BY WED NIGHT AS THE MAIN JET IS WELL EAST OF COLORADO.
HOWEVER...THE MOUNTAIN TOP LEVEL STABILITY LOOKS QUITE IMPRESSIVE AS
STRONG MID LEVEL WARMING DEVELOPS A STRONG INVERSION IN THE
700-750MB LAYER. ALONG WITH THE TIGHTENING SURFACE GRADIENT THIS
SHOULD HELP SHIFT THE STRONGER WINDS DOWN OVER THE LOWER FOOTHILLS
AND AT THE BASE OF THE FOOTHILLS. ON THE OTHER HAND...INCREASING
MOISTURE IN THE MOUNTAINS ON WEDNESDAY MAY HELP NEGATE THE STRONGEST
WINDS AND DIMINISH THE MOUNTAIN WAVE EFFECTS. STILL ENOUGH FACTORS
TO WARRANT A HIGH WIND WATCH GIVEN THE VERY STRONG MOUNTAIN TOP FLOW
AROUND 80KTS. WILL PLAY THE WATCH TIMING IN A RATHER BROAD SCOPE FOR
NOW BUT HOPEFULLY ABLE TO NAIL DOWN TIMING AND STRENGTH BETTER IN
THE NEXT FEW DAYS.
THE NEXT QUESTION WILL BE WHAT TO DO WITH ZONES 33 AND 34 IN TERMS
OF WIND VERSUS SNOW POTENTIAL...BUT THINK THE WIND WILL BE THE
BIGGEST FACTOR HERE. MOISTURE DEPTH DOES INCREASE WEDNESDAY
AFTERNOON AND NIGHT BUT GIVEN THE INCREASING STABILITY...LAPSE RATES
DECREASE TO 2.5-4C/KM BY WED NIGHT. LOCAL SNOW MODEL GENERATES UNDER
ADVISORY AMOUNTS FOR NOW. WILL AT LEAST BUMP UP POPS TO LIKELY FOR
ZONES 31 AND 33 GIVEN THE STRONG WESTERLY OROGRAPHIC FLOW.
ACROSS LOWER ELEVATIONS IT WILL BE A DRY AND A MILD WEEK AHEAD WITH
TEMPERATURES WELL ABOVE NORMAL BY MIDWEEK WITH READINGS IN THE 50S
AND LOWER 60S THROUGH THE WEEKEND.
AVIATION...COLD FRONT ALREADY SLIPPING INTO NORTHEAST COLORADO FROM
WYOMING AS OF 22Z. AS THIS FRONT MOVES SOUTH ALONG THE FOOTHILLS
SHOULD SEE BANDS OF LIGHT SNOWFALL FORMING ALONG AND BEHIND THIS
FRONTAL BOUNDARY. AT CURRENT SPEED COULD SEE THE FRONT AND ITS
ASSOCIATED SHIFT TO GUSTY NORTH-NORTHEAST WINDS IN THE NEXT 60 TO 90
MINUTES...WITH THE HEAVIER SHOWERS BEHIND THIS BOUNDARY. MVFR
CEILINGS NOW ARE EXPECTED TO LOWER TO LOWER TO BELOW 3000 FEET AGL
AFTER 00Z/TUE WIT LOCAL LIFR CEILINGS WIT PASSING SNOW SHOWERS.
HEAVIER SHOWERS COULD ALSO PRODUCE VSBYS BELOW 2 MILES. AT THIS
TIME...IT APPEARS THAT PASSING SNOW SHOWERS WILL PRODUCE MINIMAL
SNOW ACCUMULATION IN THE DENVER ARE...PROBABLY NO MORE THAN A HALF
INCH ON GRASSY SURFACES. SHOWERS ARE EXPECTED TO MOVE OUT OF THE
DENVER AREA BY AROUND 05Z THIS EVENING...AND BY 07Z...SHOULD SEE
SKIES CLEARING WITH A SURGE OF DRIER AND COLDER AIR MOVING DOWN FROM
WYOMING. ON TUESDAY...VFR CONDITIONS WITH LIGHT WEST TO SOUTHWEST
BREEZES FOR MOST OF THE DAY UNDER MOSTLY CLEAR SKIES.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM LATE TUESDAY NIGHT THROUGH THURSDAY MORNING
FOR COZ033>036-038-039.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....ENTREKIN
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION...UPDATED
NWS PUEBLO CO
1038 PM MST MON JAN 16 2012
.UPDATE...
UPPER TROF AXIS WILL CONTINUE SHIFTING EAST OF THE AREA WITH SNOW
SHOWERS QUICKLY DIMINISHING ACROSS THE CENTRAL MTS. ALREADY SEEING
A MARKED DECREASE IN ECHOES IN AREA RADARS/SAT LOOPS OUT WEST.
THUS PLAN TO LET THE WINTER WEATHER ADVISORY FOR THE SAWATCH RANGE
EXPIRE AT 11 PM. SOME LIGHT BANDED SNOW SHOWERS WILL CONTINUE
ACROSS PORTIONS OF THE SE PLAINS THROUGH MIDNIGHT BEFORE
DIMINISHING QUICKLY THEREAFTER. LITTLE TO NO ACCUMULATION IS
EXPECTED. OTHERWISE...COLD AIR WILL CONTINUE SETTLING IN ACROSS
THE PLAINS BEHIND THE FRONT. TEMPERATURES ARE ALREADY DROPPING
INTO THE SINGLE DIGITS AND LOWER TEENS ACROSS NE CO...AND SUSPECT
THAT READINGS ACROSS THE PLAINS WILL DROP INTO THE LOWER TEENS BY
MORNING. MAY TWEAK TEMPS DOWN A COUPLE DEGREES OUT EAST. ELSEWHERE
FORECAST STILL LOOKS ON TRACK WITH SOME MINOR CHANGES PLANNED TO
DECREASE POPS A BIT SOONER BEHIND DEPARTING SYSTEM. -KT
&&
.AVIATION...
BRIEF -SHSN HAS ENDED AT KCOS AND EXPECT CLEARING SKIES FOR
THE REMAINDER OF THE NIGHT. EXPECT WINDS TO SWING AROUND FROM THE
EAST TO SOUTHEAST AT KCOS AND KPUB OVERNIGHT. THIS LIGHT UPSLOPE
COULD BE SUFFICIENT TO PRODUCE A FEW020 LAYER AT KCOS TOWARDS
12Z...BUT MOST MODELS SHOW SUFFICIENT DRY AIR ALOFT BEHIND THE
DEPARTING SYSTEM TO PREVENT A WIDESPREAD STRATUS LAYER IN SPITE OF
THE LIGHT UPSLOPE WINDS. WILL CONTINUE TO MONITOR THIS BUT WILL
NOT INTRODUCE THIS INTO TAF GIVEN ITS LOW PROBABILITY OF
OCCURENCE. OTHERWISE...MOSTLY CLEAR SKIES EXPECTED FOR TUESDAY
WITH INCREASING S-SE WINDS 10-15 KTS FOR KCOS AND KPUB. KALS WILL
SEE A BRIEF PERIOD OF GUSTY WEST WINDS EARLY IN THE PERIOD...WITH
WINDS BECOMING LIGHT AFTER 08Z UNTIL TUES AFTN WHEN SW WINDS WILL
INCREASE AT 10-15 KTS. -KT
&&
.PREV DISCUSSION... /ISSUED 617 PM MST MON JAN 16 2012/
UPDATE...
UPDATED FORECAST PACKAGE TO TAKE DOWN WINTER WEATHER HIGHLIGHTS
FOR THE SOUTHWEST MOUNTAINS. BACK EDGE OF SNOW ALONG LEADING EDGE
OF TROF AXIS WILL CONTINUE MOVING THROUGH THE CENTRAL MTS AND
ACROSS EAST CENTRAL CO OVER THE NEXT SEVERAL HOURS. HAVE INCREASED
POPS FOR NRN EL PASO COUNTY WHERE RUC13 AND LATEST RADAR TRENDS
SUGGEST AT LEAST A PERIOD OF SCATTERED SNOW SHOWERS ALONG THE NRN
EL PASO CO BORDER THROUGH 04Z. NOT EXPECTING MUCH ACCUMULATION AS
THESE SHOULD BE FAIRLY BRIEF IN NATURE. -KT
PREV DISCUSSION... /ISSUED 226 PM MST MON JAN 16 2012/
SHORT TERM...
(TONIGHT AND TUESDAY)
CURRENTLY...
PACIFIC FRONT HAS MOVED EAST OF THE I-25 CORRIDOR AND WAS LOCATED BY
RADAR AT 1 PM ALONG THE PUEBLO/OTERO AND CROWLEY COUNTY LINE. SAT
PIX AND SIMULATIONS SHOW BROAD TROUGH AT MID LEVELS WAS LOCATED OVER
THE E UTAH AND WAS PROGRESSING EAST. CLOUDINESS ASSOCIATED WITH THE
TROUGH OVER THE MTNS WAS BECOMING MORE CONVECTIVE IN NATURE AND
CLOUD TOPS WERE WARMING...ESPECIALLY OVER THE S CO.
REST OF TODAY AND THIS EVENING...
AS PAC FRONT MOVES EAST ACROSS THE E PLAINS...TEMPS WILL LIKELY RISE
FROM THEIR CURRENT VALUES. THIS PAC FRONT WILL LIKELY ADVANCE AS FAR
EAST AS W KIOWA/KLAA/KSPD LINE BEFORE CRASHING INTO THE MODIFIED
ARCTIC BOUNDARY THAT WILL DROP SOUTH/BACK DOOR INTO THE AREA ACROSS
THE REGION THIS EVENING. WITH THE STRONG WESTERLY WINDS BLOWING OVER
MOST OF THE PLAINS THIS EVENING TEMPS WILL ONLY GRADUALLY DROP...AND
WILL REMAIN ON THE MILD SIDE UNTIL THE ARCTIC FRONT MOVES THROUGH.
AS BROAD TROUGH GETS CLOSER WINDS AT MTN TOP LEVELS WILL SHIFT TO A
MORE WESTERLY AND THEN NORTHWESTERLY COMPONENT. SNOWS ACROSS THE SAN
JUANS WILL GRADUALLY DECREASE AS THIS HAPPENS AND PLAN TO LET THE
ADVISORY END AT ITS SCHEDULED TIME (6 PM). SNOW WILL CONTINUE ACROSS
THE CENTRAL MTNS INTO THE MID EVENING HOURS.
LATER TONIGHT...
MODIFIED ARCTIC BOUNDARY SHOULD ENTER KIOWA COUNTY AND NORTHERN EL
PASO COUNTY AROUND 03-04Z. WE WILL LIKELY SEE SOME INCREASE IN
CLOUDS AND CANNOT RULE OUT A BRIEF SNOW SHOWER NORTH OF US50 AS THE
BOUNDARY MOVES THROUGH. THE BOUNDARY WILL THEN CONTINUE TO DROP
SOUTH AND WILL BE THROUGH THE ENTIRE CWA BY 09Z.
WINDS OVER THE HIGHER TRRN WILL ABATE CONSIDERABLY.
TOMORROW...
IT WILL BE MOSTLY SUNNY MOST AREAS BUT IT WILL BE MUCH COLDER THAN
TODAY. HIGH TEMPS WILL LIKELY ONLY IN THE LOWER TO MID 30S ACROSS
MOST OF THE REGION. AREAS WHICH MAY BE A BIT WARMER WILL BE DOWN
NEAR KTAD WHERE DOWNSLOPE OFF THE RATON MESA MAY ALLOW TEMPS TO
APPROACH NEAR 40. OVER THE MTNS ALONG THE CONTDVD EXPECT PARTLY
CLOUDY SKIES WITH ISOLD SNOW SHOWERS...ESPECIALLY OVER THE C MTNS.
WINDS OVER THE MTNS WILL BE PICKING UP ONE AGAIN AS ANOTHER SPEED
MAX APPROACHES THE REGION. BY LATE IN THE DAY WINDS WILL BE IN THE
20 TO 40 MPH RANGE...ESPECIALLY C MTNS AND PIKES PEAK.
LONG TERM...
(TUESDAY NIGHT THROUGH MONDAY)
.CONTINUING MOUNTAIN SNOW AND BREEZY CONDITIONS...
ZONAL FLOW IS FORECAST TO PERSIST THROUGH MUCH OF THE EXTENDED
WITH SEVERAL EMBEDDED WAVES AND PERIODS OF STRONG GUSTY WINDS. THE
PATTERN WILL BE DOMINATED BY A LARGE LOW PRESSURE CENTER OVER
CENTRAL CANADA WHICH WILL PRODUCE THE ZONAL FLOW.
THE FIRST MAIN CONCERN WILL BE THE POTENTIAL FOR STRONG WINDS
TUESDAY NIGHT INTO WEDNESDAY MORNING. A SHORTWAVE TROUGH IS
FORECAST TO TRACK ACROSS WYOMING INTO THE CENTRAL PLAINS WITH A
STRONG JET STREAM MOVING OVER THE ROCKIES. MODELS INDICATING A
PERIOD...ROUGHLY FROM 03Z THROUGH AROUND 18Z WEDNESDAY FOR STRONG
WINDS. DOWNSLOPE POTENTIAL DOES NOT LOOK OVERLY GREAT WITH BRUTE
FORCE BEING THE MOST LIKELY SCENARIO. THINK THE ELEVATIONS ABOVE
11 KFT WILL LIKELY SEE GUSTS IN EXCESS OF 80 MPH WHILE THE LOWER
ELEVATIONS SEE GUSTS UP TO 50 MPH. THE STRONGEST WINDS WILL LIKELY
OCCUR ALONG THE EASTERN MOUNTAINS AND ADJACENT PLAINS WEST OF
I-25. WINDS WILL SUBSIDE DURING THE LATE AFTERNOON AS THE UPPER
LEVEL JET AND TROUGH SHIFT EAST OF THE REGION. MODELS ALL
DEVELOPING LIGHT SNOWFALL TUESDAY NIGHT AND WEDNESDAY ACROSS THE
CENTRAL MOUNTAINS BUT ACCUMULATIONS WILL ONLY BE AN INCH OR TWO.
THE NEXT FAST MOVING SHORTWAVE TROUGH IS FORECAST TO MOVE ACROSS
THE ROCKIES WEDNESDAY EVENING INTO THURSDAY. EXPECT LIGHT SNOW TO
SPREAD SOUTH ALONG THE CONTINENTAL DIVIDE INTO THE SAN JUANS
DURING THIS TIME PERIOD. AGAIN SNOW ACCUMULATIONS WILL BE MINOR
WITH ONLY AN INCH OR TWO.
A STRONGER STORM SYSTEM IS FORECAST TO MOVE INTO THE REGION FRIDAY
THROUGH SUNDAY WITH A CHANCE AT HEAVIER SNOW FOR THE CONTINENTAL
DIVIDE. EXPECT LIGHT SNOW TO PICK UP IN INTENSITY FRIDAY NIGHT AS
THE MAIN JET CORE BEGINS TO MOVE OVER THE ROCKIES. THERE APPEARS
TO BE ANOTHER SHOT AT DOWNSLOPE WINDS FRIDAY NIGHT INTO SATURDAY
MORNING BASED ON THE GFS SOUNDING AND MID LEVEL DATA. CURRENT
SOUNDINGS INDICATE A NICE MOUNTAIN TOP INVERSION WITH SOME WEAK
REVERSE SHEAR WHICH ARE ALL CONDUCIVE TO DOWNSLOPE WINDS. FOR NOW
HAVE STARTED TO INCREASE MOUNTAIN AND LEE SLOPE WINDS WHICH WILL
HAVE TO BE MONITORED.
MODELS IN SLIGHTLY BETTER AGREEMENT THIS AFTERNOON IN REGARDS TO
THE POTENTIAL FOR A STRONG SNOW STORM BEGINNING ON MONDAY. THERE
ARE MODEL DIFFERENCES IN STORM TRACK AND WIND FIELDS...BUT SOME OF
THE MODEL SOLUTIONS SUGGEST AN ACCUMULATING SNOW STORM FOR ALL OF
SOUTHERN COLORADO. THIS IS STILL A LONG WAYS OUT BUT WILL HAVE TO
BE WATCHED.
TEMPERATURES...WITH WESTERLY DOWNSLOPING WINDS...AFTERNOON HIGHS
WILL CLIMB INTO THE MID TO UPPER 50S FOR THE PLAINS. THE EXCEPTION
WILL BE THE LOWER ARKANSAS RIVER VALLEY WHERE HIGHS WILL REMAIN IN
THE 40S WITH WARMER TEMPERATURES BY THE END OF THE WEEK. 88
AVIATION...
VFR EXPECTED NEXT 24H AT ALL 3 TAF SITES...KCOS...KPUB AND KALS.
GUSTY WINDS WILL CONTINUE AT KPUB AND KCOS THIS EVENING BEFORE
DECREASING LATER THIS EVENING. PAC FRONT HAS ALREADY CROSSED THE
PLAINS TAF SITES AND THE ARCTIC FRONT WILL GRADUALLY MOVE THROUGH
THIS EVENING.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR COZ060.
&&
$$
31/44
AREA FORECAST DISCUSSION
NWS DENVER CO
910 PM MST MON JAN 16 2012
.UPDATE...SNOW IS DECREASING RATHER QUICKLY AND PRETTY MUCH ON
TRACK. ONE BAND OF SNOW STILL LINGERED FROM FORT COLLINS TO
DIA...WITH ANOTHER STRETCHING FROM THE PALMER DIVIDE THROUGH EAST
CENTRAL COLORADO. MOUNTAIN AREAS HAVE ALSO SEEN SNOW DECREASE
SHARPLY LATE THIS EVENING. OVERALL FORECAST IS ON TRACK WITH SNOW
ENDING BY/SHORTLY AFTER MIDNIGHT WITH CLEARING SKIES AND COLD
TEMPERATURES OVERNIGHT.
&&
.AVIATION...SNOW IS DECREASING SO CURRENT TRENDS INDICATE SNOW
WILL BE ALL BUT GONE AT KDEN BY 06Z. KAPA AND KBJC SHOULD SEE
FLURRIES WRAP UP IN THE NEXT HOUR. THEN CEILINGS WILL GRADUALLY
LIFT AND BREAK UP BETWEEN 06Z AND 09Z.
&&
.PREV DISCUSSION... /ISSUED 453 PM MST MON JAN 16 2012/
UPDATE...LATEST RADAR SHOWS A GOOD BAND OF SNOW ASSOCIATED WITH
UPPER TROUGH AND MID LEVEL COLD FRONT SPREADING OFF THE FOOTHILLS.
WE HAVE INCREASED SNOW CHANCES FOR DENVER METRO AREA AND NORTHEAST
ACROSS THE PLAINS DUE TO THIS FEATURE...AND SHALLOW UPSLOPE
SLOWING DISSIPATION OF THE BAND IN MEAN WESTERLY FLOW ALOFT.
AVIATION...CURRENT FORECAST IS ON TRACK WITH SHOWERS SPREADING
SOUTHEAST ACROSS THE FRONT RANGE AIRPORTS FROM NOW TIL 04Z.
VISIBILITIES COULD DROP TO 1/2 MILE AND BRIEFLY 1/4 MILE IN THE
HEAVIEST SHOWERS PER UPSTREAM OBS FROM KCYS AND FORT COLLINS
SPOTTER REPORTS...SO HAVE LOWERED THE TEMPO VSBYS IN TAFS.
PREV DISCUSSION... /ISSUED 335 PM MST MON JAN 16 2012/
SHORT TERM...WIDE BAROCLINIC ZONE ASSOCIATED WITH THE UPPER TROUGH
AND SFC COLD FRONT PASSING OVER THE MOUNTAINS AT THIS HOUR. FRONTAL
BNDRY HAS MOVED THROUGH JACKSON COUNTY AS NOTED BY A SUDDEN DROP IN
TEMPERATURE AND ABRUPT SHIFT TO NORTHWEST WINDS AT WALDEN WHERE THE
TEMPERATURE FELL 11 DEGS F IN LESS THAN AN HOUR. BANDED SLANTWISE
CONVECTION...I.E. SNOWFALL...STREAKING CROSSING THE HIGH COUNTRY
JUST AHEAD OF THE 700-500MB TROUGH AXIS. HAVE NOTICED A STEADY
INCREASE IN SNOW INTENSITY AND COVERAGE IN THE PAST COUPLE OF HOURS
WITH RUC QG VERTICAL FIELDS INDICATING WEAK TO MODERATE LARGE SCALE
ASCENT CENTERED OVER THE NRN MTNS. WHERE THIS PRECIP GOES FROM HERE
AND HOW EXTENSIVE IT WILL BE DEPENDS ON WHICH MODEL YOU LOOK AT.
BOTTOM LINE...THE NAM IS DRIER AND A BIT SLOWER WITH ITS EASTWARD
PROGRESS THAN THE GFS...ECMWF AND SREF. WHEREAS...THE GFS AND SREF
SHOW A WIDER AREA OF PRECIPITATION/SNOW FIELD ACROSS NERN COLORADO
THIS EVENING...WITH A COUPLE INCHES OF SNOW ACCUM BY MIDNIGHT
ACROSS THE NORTHEAST CORNER OF THE STATE. OVERALL SEE BANDED PRECIP
TRANSLATING SOUTHWARD ACROSS THE NERN PLAINS THIS EVENING...WITH THE
BACK EDGE OF THIS PRECIP SOUTHEAST OF THE DENVER METRO AREA BY
AROUND 05Z..AND OUT OF THE CWFA (LINCOLN COUNTY) POSSIBLY BY 08Z OR
09Z TONIGHT. EXPECTED SNOW ACCUMULATION WITHIN THE I-25 URBAN
CORRIDOR MINIMAL AT BEST...PERHAPS A HALF INCH ON GRASSY SURFACES
FROM ONE OF THE HEAVIER SNOW BANDS COMING OFF THE FOOTHILLS EARLY
THIS EVENING. AGAIN...APPEARS THE NORTHEAST CORNER IN THE BEST
POSITION TO SEE ACCUMULATING SNOWFALL THIS EVENING.
LATER TONIGHT...SHOULD SEE GUSTY NORTHWEST WINDS USHERING IN DRIER
AND COLDER AIR FROM WYOMING. CLEARING LATE WILL ALLOW FOR STRONG
RADIATIONAL COOLING CAUSING TEMPERATURES TO PLUNGE WELL BELOW ZERO
IN THE HIGH MOUNTAIN VALLEYS. MIN TEMPERATURES ALSO QUITE COLD ON
THE PLAINS WITH SINGLE DIGITS ABOVE ZERO THE NORM BY MORNING LIGHT.
COULD SEE A FEW SUBZERO READINGS IN LOW LYING AREAS SUCH AS ALONG
THE SOUTH PLATTE RIVER.
ON TUESDAY...SWIFT NORTHWEST FLOW ALOFT CONTINUES OVER THE STATE
WITH A DRIER AIRMASS UPSTREAM. ANY SNOWFALL TOMORROW WILL BE
CONFINED TO THE HIGHEST PEAKS AND WEST FACING SLOPES ALONG THE
DIVIDE. EVEN THERE SNOW INTENSITIES WILL BE WEAK. TEMPERATURES WILL
STRUGGLE TO WARM TOMORROW WITH ONGOING COLD AIR ADVECTION. SEE
LITTLE CLOUD COVER ESPECIALLY EAST OF THE MTNS WITHE FLOW
REGIME.
LONG TERM...MAIN CONCERN FOR THE UPCOMING WEEK WILL BE THE HIGH
WIND POTENTIAL IN THE MOUNTAINS...FOOTHILLS AND ADJACENT PLAINS AND
DEVELOPING SNOW IN THE MOUNTAINS BY MIDWEEK. MOST OF THE WESTERN
U.S. WILL TRANSITION TO A STRONG AND ZONAL WEST TO NORTHWEST FLOW
ALOFT THIS WEEK. IT APPEARS THE STRONGEST WINDS WILL EFFECT THE
REGION LATE TUE NIGHT THROUGH EARLY THURSDAY AM AS A STRONG
130-150KT JET CORE LIFTS OUT ACROSS WYOMING ON WEDNESDAY. THE
SURFACE PRESSURE GRADIENT WILL TIGHTEN TO 10-15 MB ACROSS THE STATE
ON WED WHILE MOUNTAIN TOP STABILITY INCREASES. CROSS SECTIONS SHOW
AMPLIFIED MOUNTAIN WAVE DEVELOPING WITH 60-80KT OF CROSS BARRIER
FLOW. STILL A LOT OF QUESTION MARKS AS THERE ARE SOME CONFLICTING
PARAMETERS. THERE IS A LOT OF VERTICAL SHEAR ESPECIALLY EARLY ON
WEDNESDAY FOR AN AMPLIFIED MOUNTAIN WAVE. SHEAR PROFILE IMPROVES A
BIT BY WED NIGHT AS THE MAIN JET IS WELL EAST OF COLORADO.
HOWEVER...THE MOUNTAIN TOP LEVEL STABILITY LOOKS QUITE IMPRESSIVE AS
STRONG MID LEVEL WARMING DEVELOPS A STRONG INVERSION IN THE
700-750MB LAYER. ALONG WITH THE TIGHTENING SURFACE GRADIENT THIS
SHOULD HELP SHIFT THE STRONGER WINDS DOWN OVER THE LOWER FOOTHILLS
AND AT THE BASE OF THE FOOTHILLS. ON THE OTHER HAND...INCREASING
MOISTURE IN THE MOUNTAINS ON WEDNESDAY MAY HELP NEGATE THE STRONGEST
WINDS AND DIMINISH THE MOUNTAIN WAVE EFFECTS. STILL ENOUGH FACTORS
TO WARRANT A HIGH WIND WATCH GIVEN THE VERY STRONG MOUNTAIN TOP FLOW
AROUND 80KTS. WILL PLAY THE WATCH TIMING IN A RATHER BROAD SCOPE FOR
NOW BUT HOPEFULLY ABLE TO NAIL DOWN TIMING AND STRENGTH BETTER IN
THE NEXT FEW DAYS.
THE NEXT QUESTION WILL BE WHAT TO DO WITH ZONES 33 AND 34 IN TERMS
OF WIND VERSUS SNOW POTENTIAL...BUT THINK THE WIND WILL BE THE
BIGGEST FACTOR HERE. MOISTURE DEPTH DOES INCREASE WEDNESDAY
AFTERNOON AND NIGHT BUT GIVEN THE INCREASING STABILITY...LAPSE RATES
DECREASE TO 2.5-4C/KM BY WED NIGHT. LOCAL SNOW MODEL GENERATES UNDER
ADVISORY AMOUNTS FOR NOW. WILL AT LEAST BUMP UP POPS TO LIKELY FOR
ZONES 31 AND 33 GIVEN THE STRONG WESTERLY OROGRAPHIC FLOW.
ACROSS LOWER ELEVATIONS IT WILL BE A DRY AND A MILD WEEK AHEAD WITH
TEMPERATURES WELL ABOVE NORMAL BY MIDWEEK WITH READINGS IN THE 50S
AND LOWER 60S THROUGH THE WEEKEND.
AVIATION...COLD FRONT ALREADY SLIPPING INTO NORTHEAST COLORADO FROM
WYOMING AS OF 22Z. AS THIS FRONT MOVES SOUTH ALONG THE FOOTHILLS
SHOULD SEE BANDS OF LIGHT SNOWFALL FORMING ALONG AND BEHIND THIS
FRONTAL BOUNDARY. AT CURRENT SPEED COULD SEE THE FRONT AND ITS
ASSOCIATED SHIFT TO GUSTY NORTH-NORTHEAST WINDS IN THE NEXT 60 TO 90
MINUTES...WITH THE HEAVIER SHOWERS BEHIND THIS BOUNDARY. MVFR
CEILINGS NOW ARE EXPECTED TO LOWER TO LOWER TO BELOW 3000 FEET AGL
AFTER 00Z/TUE WIT LOCAL LIFR CEILINGS WIT PASSING SNOW SHOWERS.
HEAVIER SHOWERS COULD ALSO PRODUCE VSBYS BELOW 2 MILES. AT THIS
TIME...IT APPEARS THAT PASSING SNOW SHOWERS WILL PRODUCE MINIMAL
SNOW ACCUMULATION IN THE DENVER ARE...PROBABLY NO MORE THAN A HALF
INCH ON GRASSY SURFACES. SHOWERS ARE EXPECTED TO MOVE OUT OF THE
DENVER AREA BY AROUND 05Z THIS EVENING...AND BY 07Z...SHOULD SEE
SKIES CLEARING WITH A SURGE OF DRIER AND COLDER AIR MOVING DOWN FROM
WYOMING. ON TUESDAY...VFR CONDITIONS WITH LIGHT WEST TO SOUTHWEST
BREEZES FOR MOST OF THE DAY UNDER MOSTLY CLEAR SKIES.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WATCH FROM LATE TUESDAY NIGHT THROUGH THURSDAY MORNING
FOR COZ033>036-038-039.
&&
$$
SHORT TERM...BARJENBRUCH
LONG TERM....ENTREKIN
AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS ALBANY NY
435 PM EST TUE JAN 17 2012
.SYNOPSIS...
LOW PRESSURE WILL DEEPEN AND INTENSIFY...AS MOVES ALONG
THE SAINT LAWRENCE RIVER VALLEY TONIGHT. THE COLD FRONT TO THE
SYSTEM WILL SWING ACROSS EASTERN NEW YORK AND WESTERN NEW ENGLAND
OVERNIGHT...WITH SCATTERED SNOW SHOWERS...BLUSTERY...AND COLD
CONDITIONS FOR WEDNESDAY. HIGH PRESSURE WILL BRIEFLY BUILD IN
WEDNESDAY AFTERNOON INTO THURSDAY MORNING...AS A CLIPPER LOW WILL
BRING SOME SCATTERED SHOWERS SHOWERS LATE THURSDAY AFTERNOON THROUGH
THURSDAY NIGHT.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
AS OF 4 PM...IT HAS BEEN ANOTHER ACTIVE AND BUSY DAY ACROSS THE
ALY FORECAST AREA. THE NRN TIER HAS HAD MANY LOCATIONS HUNG UP IN
THE UPPER 20S TO NEAR THE FREEZING MARK IN THE THE MID TO LATE
PM...AS THE CURRENT AREA OF PCPN ON THE KENX/NORTHEAST MOSAIC
RADAR HAS PRODUCED PERIODS OF FREEZING RAIN. WE HAD ONE REPORT
COME IN AT 3 PM IN FAIRFIELD OF HERKIMER COUNTY WITH TWO TENTHS OF
AN INCH OF ICE...AND A TEMP OF 31F. THE POTENT LOW PRESSURE SYSTEM
APPROACHING FROM JUST NORTHEAST OF LAKE ERIE THIS HOUR HAS A
DOUBLE WARM FRONT STRUCTURE. THE FIRST WEAK WARM FRONT WENT
THROUGH MOST THE REGION THIS MORNING. A SECOND WARM FRONT OR
THERMAL TROUGH WITH A SHORT-WAVE IN THE SW FLOW HAS FOCUSED THE
AREA OF PCPN. WE WILL BE EXTENDING THE WINTER WEATHER ADVISORY FOR
THE ERN DACKS...LAKE GEORGE-NRN SARATOGA REGION...AND SRN VT
UNTIL 7 PM. WE WILL BE EXPIRING HERKIMER...MONTGOMERY...SRN FULTON
COUNTIES AT 4 PM...AND PHRASE IT AS POCKETS OF FREEZING RAIN...AS
THE LATEST MESONET SITES SHOW TEMPERATURES WARMING ABOVE FREEZING
AT THIS TIME IN THESE SPOTS.
THE OTHER BIG ISSUE TONIGHT IS THE SFC CYCLONE MOVING NORTHEAST
ALONG THE ST LAWRENCE RIVER VALLEY. THE NAM20 INDICATES AN
IMPRESSIVE ISALLOBARIC RISE-FALL PRESSURE COUPLET. WE ARE
EXPECTING 10-12 HPA/3 HRS RISES MOVING NEAR MASSENA WITH THE
DEEPENING AND INTENSIFYING WAVE EARLY THIS EVENING. THE GREATEST PRESSURE
RISES IN OUR AREA ARE 5-6 HPA/3 HRS. WE HAVE EXPANDED THE WIND
ADVISORY TO INCLUDE THE WRN AND SRN DACKS...LAKE GEORGE NRN
SARATOGA REGION...AND SRN VT...AS WELL AS NRN LITCHFIELD CTY CT.
BASICALLY OUR ENTIRE FCST AREA IS IN A WIND ADVISORY BY 10 PM
TONIGHT TO 3 PM TOMORROW...EXCEPT FOR THE MID HUDSON VALLEY /ERN
ULSTER...AND DUTCHESS COUNTIES/...AND SRN LITCHFIELD CTY CT.
THANKS FOR THE COLLABORATION WITH BOX AND OKX FOR THE ADDITION OF
NRN LITCHFIELD CTY. THE H850 WINDS RAMP UP TO 50-70 KTS
TONIGHT...INITIALLY NORTH AND WEST OF KALB PRIOR TO
MIDNIGHT...THEN THEY OVERSPREAD THE REGION. THE 925 HPA WINDS
INCREASE TO 35-50 KTS BTWN 06Z-12Z WITH STRONG COLD AIR ADVECTION
OCCURRING ACROSS THE REGION WITH THE PASSAGE OF THE COLD FRONT.
THE LATEST 18Z NAM40 GUIDANCE HAS H850 TEMPS FALL TO -10C TO -15C
BY 12Z. WE MAY HAVE OUR ACTUAL MAX TEMPS OCCUR AROUND OR SHORTLY
AFTER 12Z TOMORROW.
THERE WILL BE A PERIOD OF UPSLOPE SNOWFALL ALONG THE WRN SPINE OF
THE WRN DACKS...N-CNTRL TACONICS...AND THE SRN GREENS. THE SHOWERS
QUICKLY TRANSITION TO SNOW SHOWERS WITH THE FRONTAL PASSAGE BTWN
03Z-06Z FROM KALB NORTH AND WEST...AND 06Z-09Z SOUTH AND EAST. WE
ARE DEALING WITH A OPEN WAVE...AND THE PERIOD OF OROGRAPHIC
UPSLOPE SNOWFALL SHOULD BE QUICK WITH POSSIBLY 1 TO 4 INCHES
ACROSS THE SRN DACKS/WRN MOHAWK VALLEY...AND 1-2 INCHES OVER THE
SRN GREENS.
WE DID NOT ISSUE ANY LAKE EFFECT/WINTER WX HEADLINES AT THIS TIME.
AGAIN...THE LATEST HIRES WRF...AND HRRR SHOW A NARROW PERIOD WITH
THIS SNOWFALL WITH IT TRANSLATING TO SOME MULTIBANDS TOWARDS
DAYBREAK. WE WILL CONTINUE TO EVALUATE IF ANY HEADLINES ARE
NEEDED...BUT AT THIS TIME THE WINDS LOOK LIKE THE BIGGEST ISSUE.
EXPECT TEMPS TO FALL INTO THE TEENS OVER THE SRN DACKS...AND 20S
OVER MOST OF THE REST OF THE REGION...EXCEPT FOR THE THE MID
HUDSON VALLEY...AND SRN LITCHFIELD CTY WHERE SOME LOWER 30S ARE POSSIBLE.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
TOMORROW...THE BUFKIT MOMENTUM TRANSFER PROFILES INDICATE WIND
ADVISORY GUSTS ARE STILL POSSIBLE INTO THE AFTERNOON...ESPECIALLY
IF WE MIX TO 875-900 HPA OR SO. IF WE MIX HIGHER...THEN WE COULD
APPROACH SOME 50 KT GUSTS. OVERALL...NW WIND GUSTS OF 45-55 MPH
ARE POSSIBLE UNTIL ABOUT 20Z. KPOU IS MARGINAL WITH THE GUST
POTENTIAL AROUND 35 KTS OR SO. WE KEPT THAT LOCATION OUT OF THE
WIND ADVISORY. BLUSTERY AND COLD CONDITIONS WILL PERSIST WITH
TEMPS FALLING IN THE 20S AND TEENS IN THE AFTERNOON WITH COLD
ADVECTION CONTINUING WITH H850 TEMPS FALLING TO -15C TO -20C. THE
NW FLOW FAVORS MULTIBANDS OVER CNTRL NY TOMORROW. SOME OF THE
NARROW MULTIBANDS CREEP INTO THE WRN MOHAWK VALLEY...AND ERN
CATSKILLS. A COATING TO AN INCH OR TWO OF SNOW IS POSSIBLE. WE
TENDED TO DECREASE THE POPS TO SLIGHT OR LOW CHC VALUES OVER THE
SRN GREENS...NRN TACONICS...AND BERKSHIRES WITH THE BOUNDARY LAYER
DRYING OUT /WE ARE LOSING THE MOISTURE HERE/ AND THE MESOSCALE
GUIDANCE SHOWING LESS OF AN UPSLOPE EVENT.
IN THE LATE AFTERNOON...THE UPSTREAM SOUNDINGS OVER KYSR...AND
KRME SHOW THE SUBSIDENCE INVERSION LOWERING TO 4-5 KFT AGL
SQUELCHING ANY LAKE EFFECT SNOW.
WEDNESDAY NIGHT...HIGH PRESSURE QUICKLY RIDGES IN OVER NY AND NEW
ENGLAND WITH COLD AND DRY WEATHER. THE WINDS WILL SUBSIDE...AND
EXPECT DECENT RADIATIONAL COOLING WITH LOWS ZERO TO 10 BELOW OVER
THE LAKE GEORGE REGION...AND SOUTHERN ADIRONDACKS...SINGLE DIGITS
ELSEWHERE...EXPECT 10 TO 15F IN THE MID HUDSON VALLEY...AND SRN
LITCHFIELD CTY CT.
THU-THU NIGHT...ANOTHER SYSTEM APPROACHES FROM THE GREAT LAKES
REGION AND SRN ONTARIO FOR LATE THU. MID AND HIGH CLOUDS INCREASE
DURING THE LATE MORNING INTO THE EARLY PM...AS THE WARM ADVECTION
INCREASES. WE PLACE SOME SLIGHT TO LOW CHC POPS IN DURING THE PM
FOR SOME SCT SNOW SHOWERS OR LIGHT SNOW. THE WAVE PASSES WELL
NORTH OVER S-CNTRL QUEBEC...WITH ITS ASSOCIATED WARM AND COLD
FRONTS BRINGING SOME LIGHT SNOW OR SNOW SHOWERS TO REGION WITH
LIGHT SNOW ACCUMULATIONS OF A COATING TO AN INCH OR TWO. WE WENT
WITH THE HIGHEST POPS OVER THE NRN TIER THU NIGHT.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
NO MAJOR SYSTEMS DURING THIS PERIOD...BUT AREAS OF CHC POPS FOR
MOST. THERE WILL BE WEAK HIGH PRESSURE AREAS INTERSPERSED BETWEEN
WEAK FRONTS/SYSTEMS. A RELATIVELY MODEST WARM-UP IS IN STORE DURING
THE WEEKEND. HIGH TEMPERATURES IN THE TEENS AND 20S ON FRIDAY WILL
BECOME HIGHS FROM THE MID 30S TO LOWER 50S BY MONDAY WHEN 540
1000-500 MB THICKNESSES WILL LIE JUST NORTH OF OUR ZONES. INDEED...
MONDAY WILL BE THE NICEST DAY OF THE PERIOD...WITH THE GREATEST
AMOUNT OF SUNSHINE AND LOWEST POPS. OVERNIGHT LOWS FROM THE MINUS
SINGLE DIGITS IN THE WESTERN ADIRONDACKS...TO THE LOWER 30S IN THE
MID HUDSON VALLEY...WILL MODERATE TO LOWS MOSTLY IN THE 30S SUNDAY
NIGHT AS THERE WILL BE NO REAL DIURNAL COOLING TREND GIVEN THE WARM
FRONT LIFTING THROUGH THE AREA.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
A LARGE BATCH OF RAIN SHOWERS OVER CENTRAL NEW YORK WILL BE MOVING
EASTWARD TOWARDS THE HUDSON VALLEY TAF SITES FOR THE MID TO LATE
AFTN HOURS. TEMPS HAVE WARMED UP ENOUGH IN THE BOUNDARY LAYER FOR
THIS PRECIP TO FALL AS JUST PLAIN RAIN. THIS RAIN WILL ALLOW FOR
WIDESPREAD MVFR CIGS/VSBYS...AND BRIEF PERIODS OF IFR CIGS AND
POSSIBLY VSBYS FOR KALB/KGFL. KPOU SHOULD REMAIN FAR ENOUGH SOUTH
TO AVOID MOST OF THE IFR...BUT MVFR CIGS/VSBYS LOOK LIKELY FOR THE
AFTN/EARLY EVE HOURS THERE AS WELL. SOUTHERLY WINDS WILL BE
GENERALLY FAIRLY LIGHT...LESS THAN 10 KTS.
A COLD FRONT WILL MOVE THROUGH THE AREA THIS EVENING. THIS WILL
ALLOW FOR WINDS TO SWITCH TO A SW DIRECTION AND EVENTUALLY
WESTERLY OVERNIGHT. WITH MUCH COLDER AIR MOVING IN ALOFT...BETTER
MIXING WILL OCCUR AND THE LOW CLOUDS WILL SCOUR OUT OVERNIGHT WITH
VFR CIGS/VSBYS RETURNING TO ALL TAF SITES DURING THE LATE EVENING
HOURS. WITH A STRONG AREA OF LOW PRESSURE MOVING THROUGH THE ST.
LAWRENCE VALLEY...VERY STRONG SFC WINDS WILL DEVELOP FOR LATE
TONIGHT AND INTO WEDNESDAY MORNING...MAINLY FOR KALB/KGFL. A FEW
GUSTS MAY APPROACH 40 KTS...ESP IN AREAS OF CHANNELED FLOW /SUCH
AS KALB DUE TO THE MOHAWK VALLEY/...BY WED MORNING. THERE WILL
ONLY FEW-SCT VFR CU ACROSS THE REGION FOR WED MORNING...BUT WINDS
WILL CONTINUE TO BE STRONG RIGHT INTO WED AFTN.
LLWS COULD BE AN ISSUE THIS EVENING AS STRONG WINDS OF AROUND 40
KTS MOVE IN AROUND 2 KFT AFTER 00Z. HOWEVER...SFC WINDS WILL BE
INCREASING...SO LLWS CRITERIA MAY NOT BE OFFICIALLY BE MET.
STILL...WINDS WILL BE INCREASING DURING THE OVERNIGHT HOURS AND
THIS COULD BE ADDRESSED IN FUTURE TAF ISSUANCES.
OUTLOOK...
WED PM...VFR...WINDY.
WED NIGHT...VFR. NO SIG WX.
THU...MAINLY VFR. SLIGHT CHC -SHSN WITH MVFR POSSIBLE.
FRI...VFR. NO SIG WX.
SAT...MVFR/IFR. CHC -SN/-RA.
&&
.HYDROLOGY...
NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH
THE WEEKEND.
A COLD FRONT WILL MOVE THROUGH THIS EVENING WITH SOME SCATTERED
RAIN AND SNOW SHOWERS WITH LIGHT LIQUID EQUIVALENT AMOUNTS WELL
UNDER A QUARTER OF AN INCH. THE HIGHEST SNOW TALLIES WILL BE ALONG
THE WESTERN SLOPES OF THE SOUTHERN ADIRONDACKS...AND THE SOUTHERN
GREEN MOUNTAINS TUESDAY NIGHT INTO WEDNESDAY WITH SNOWFALL AMOUNTS
OF 1 TO 4 INCHES.
COLD AND DRY WEATHER WILL PREVAIL LATE WEDNESDAY INTO THURSDAY MORNING.
A CLIPPER LOW MAY BRING SCATTERED SNOW SHOWERS OR LIGHT SNOW
THURSDAY NIGHT INTO FRIDAY. ANOTHER SYSTEM FOR THE FIRST HALF OF
THE WEEKEND MAY BRING SOME LIGHT SNOWFALL AGAIN.
ICE FORMATION OR THICKENING WILL SLOW DOWN THROUGH TONIGHT WITH A
BRIEF SPELL OF MILDER WEATHER. ICE FORMATION SHOULD INCREASE AGAIN
WEDNESDAY INTO THURSDAY AS TEMPERATURES FALL BACK WELL BELOW
FREEZING.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...WIND ADVISORY FROM 10 PM THIS EVENING TO 3 PM EST WEDNESDAY
FOR CTZ001.
NY...WIND ADVISORY FROM 10 PM THIS EVENING TO 3 PM EST WEDNESDAY
FOR NYZ032-033-038>043-047>054-058>061-063-082>084.
WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
NYZ032-033-038>043-082>084.
MA...WIND ADVISORY FROM 10 PM THIS EVENING TO 3 PM EST WEDNESDAY
FOR MAZ001-025.
VT...WIND ADVISORY FROM 10 PM THIS EVENING TO 3 PM EST WEDNESDAY
FOR VTZ013>015.
WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR
VTZ013>015.
&&
$$
SYNOPSIS...WASULA
NEAR TERM...WASULA
SHORT TERM...WASULA
LONG TERM...ELH
AVIATION...FRUGIS
HYDROLOGY...WASULA/KL
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
651 PM EST WED JAN 18 2012
.SYNOPSIS...
A PRESSURE RIDGE OVER THE FORECAST AREA TONIGHT WILL MOVE OFF THE
COAST THURSDAY. A COLD FRONT WILL MOVE INTO THE AREA FRIDAY AND
STALL.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
SURFACE RIDGE SHOULD BE OVER THE FORECAST AREA TONIGHT. RUC MODEL
IS SHOWING A VORT MAX THAT MOVES ACROSS THE FORECAST AREA 05Z-06Z.
THIS MAY BRING SOME SCATTERED MID LEVEL CLOUDS TO THE REGION BUT
SKIES ARE EXPECTED TO CLEAR AGAIN BY 08Z. SO STRONG RADIATIONAL
COOLING BEFORE DAYBREAK THURSDAY. USED RADIATIVE COOLING LOW
TEMPERATURE RADIATIVE SCHEME WHICH GAVE CAE 29 AND AGS 28. SO
LOWERED LOW TEMPERATURES ONE DEGREE.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
THE DRY AIR MASS SHOULD REMAIN IN CONTROL THURSDAY. THE NAM AND GFS
SHOW A WEAK COLD FRONT APPROACHING THURSDAY NIGHT WITH THE FRONT IN
THE FORECAST AREA FRIDAY. CONVERGENCE ASSOCIATED WITH THE FRONT AND
WARM ADVECTION SHOULD RESULT IN CONSIDERABLE CLOUDINESS FRIDAY. THE
MODELS KEEP THE MOISTURE SHALLOW AND LIFT WEAK SO THE RAIN CHANCE
APPEARS LOW. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE
FORECAST.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
CONFIDENCE IS LOW DURING THE EXTENDED PERIOD. THE GFS ENSEMBLES
SHOW HIGH SPREAD. THE OPERATIONAL GFS DISPLAYS A COLD FRONT AND
ASSOCIATED MOISTURE APPROACHING THE FORECAST AREA SATURDAY WITH
THE FRONT IN THE AREA SATURDAY NIGHT. THE FRONT APPEARS TO LINGER
SUNDAY WITH DEEPER MOISTURE SHIFTING NORTHEASTWARD. ANOTHER FRONT
APPEARS TO MOVE INTO THE FORECAST AREA MONDAY NIGHT WITH BRIEF
DRYING MONDAY...AND YET ANOTHER SYSTEM APPROACHING WEDNESDAY.
TIMING UNCERTAINTY IS HIGH BECAUSE OF THE FAST LOW AMPLITUDE
UPPER-LEVEL FLOW DURING MUCH OF THE PERIOD. LEANED TOWARD THE GFS
ENSEMBLE MEANS AND CONTINUED THE FORECAST OF CHANCE POPS THROUGH
THE PERIOD. THE LOW AMPLITUDE FLOW SHOULD HELP BRING ABOVE NORMAL
TEMPERATURES.
&&
.AVIATION /00Z THURSDAY THROUGH MONDAY/...
HIGH CONFIDENCE OF VFR CONDITIONS THROUGH THE TAF PERIOD. HIGH
PRESSURE ALONG WITH DRIER AIR WILL DOMINATE THE REGION THROUGH THE
PERIOD. THIS WILL RESULT IN SOME PASSING MID AND UPPER LEVEL
CLOUDS WITH LIGHT AND VARIABLE WINDS THROUGH 15Z...THEN BECOMING
SOUTHERLY AT 6 KNOTS OR LESS. WITH THE DRIER AIR OVER THE REGION
FOG IS NOT EXPECTED OVERNIGHT.
EXTENDED AVIATION OUTLOOK...MVFR OR LOWER CIG/VSBY ARE POSSIBLE
LATE SATURDAY MORNING INTO SUNDAY AS A COLD MOVES THROUGH THE
REGION.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
244 PM EST TUE JAN 17 2012
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
A COLD FRONT FROM CENTRAL TN THROUGH NORTH MS TO CENTRAL LA WILL
CONTINUE TO APPROACH GA THIS AFTERNOON. AREAS OF SHOWERS AND A FEW
TSTMS ARE MOVING THROUGH NORTH AL AND MOST OF MS AT THIS TIME.
THE AIRMASS OVER GA IN ADVANCE OF THE FRONT REMAINS MARGINALLY
UNSTABLE WITH LIFTED INDICES IN THE ZERO TO MINUS 2 RANGE AND
CAPES OF 300 TO 600 J/KG. MODELS STILL SHOW HIGH SHEAR WITH
HELICITIES IN THE 200 TO 400 RANGE...BUT SEVERE TSTMS ARE
UNLIKELY. SOME BRIEF STRONG WIND GUSTS UP TO 40 MPH WILL BE
POSSIBLE WITH ANY OF THE STRONGER TSTMS. OTHERWISE...WIDESPREAD
SHOWERS WITH ISOLATED TSTMS WILL OCCUR TONIGHT OVER THE FORECAST
AREA.
NAM AND GFS ARE IN GOOD AGREEMENT WITH THE TIMING OF THE COLD FRONT.
IT IS EXPECTED TO ENTER NORTHWEST GA AROUND 7 PM EST THIS EVENING...
PASS OVER THE ATLANTA METRO AREA AROUND 1 AM EST WEDNESDAY...THEN
MOVE EAST THROUGH THE REMAINDER OF THE FORECAST AREA BY 7 AM EST
WEDNESDAY MORNING. COLD HIGH PRESSURE AND DRIER AIR WILL BUILD
OVER GA WEDNESDAY THROUGH THURSDAY WITH TEMPERATURES RETURNING TO
NEAR SEASONAL NORMALS.
HYDROLOGY...
STILL EXPECTING STORM TOTAL RAINFALL AMOUNTS OF ONE HALF TO ONE
INCH ACROSS THE COUNTY WARNING AREA AS GULF MOISTURE...PWS OF 1.3
INCHES...ARE PUMPED INTO THE STATE. ISOLATED HIGHER AMOUNTS POSSIBLE
IN TSTMS. OTHER THAN SOME TEMPORARY ROAD PONDING IN SLOW DRAINING
AREAS...NO FLOODING IS EXPECTED.
16
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
MODELS AGREE ON A BRIEF DRY PERIOD THURSDAY NIGHT. A WEAK SHORT
WAVE MAY AFFECT THE NORTHWEST FRIDAY AND HAVE INCLUDED LOW POPS.
MODELS DIFFER ON LOCATION AND SPEED OF A COUPLE OF SHORT WAVES
THAT DEVELOP DURING THE WEEKEND SO HAVE LEFT CHANCE OR SLIGHT
CHANCE ACROSS THE AREA FOR SATURDAY AND SUNDAY. MORE UNCERTAINTY
FOR MONDAY WITH THE EVOLUTION OF A SOUTHERN STREAM SHORT WAVE...SO
HAVE KEPT CHANCE POPS IN FOR MONDAY.
41
AVIATION...
18Z UPDATE...
AS FIRST LINE OF SHRA HAS PUSHED THROUGH THE TERMINALS...LOW END
MVFR TO HIGH END IFR IS FILTERING IN QUICKLY. WILL CARRY THROUGH
FOR THE REMAINDER OF THE AFTERNOON UNTIL NEXT LINE OF SHRA WITH
EMBEDDED TSRA MOVES IN. LOOKS LIKE THE BEST CHANCES FOR TSRA WILL
BE FOR THE CSG TAF AND KEPT THE TEMPO IN FOR LATER THIS EVENING.
FOR THE REMAINDER OF THE SITES...23Z STILL LOOKS GOOD FOR ATL AREA
TERMINALS ALTHOUGH USING TIMING TOOLS...COULD BE A COUPLE HOURS
EITHER SIDE OF THIS. BASED ON HRRR OUTPUT AND CONSISTENCY
SAKE...JUST KEPT IT AT 23Z FOR NOW. WINDS SHOULD PICK UP OVERNIGHT
AND WILL SEE A QUICK TRANSITION FROM IFR TO MVFR AFTER 09Z. KEPT
MVFR THROUGH 12Z BEFORE SKC BECOMES PREDOMINANT FOR WED. WINDS
WILL BE GUSTY IN THE MORNING BUT SHOULD ACTUALLY DECREASE IN THE
AFTERNOON AS GRADIENT RELAXES.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM IN SHRA/TSRA TIMING.
HIGH FOR REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 44 52 29 57 / 100 5 5 10
ATLANTA 40 52 32 58 / 100 0 5 10
BLAIRSVILLE 34 44 27 51 / 100 0 5 10
CARTERSVILLE 36 48 25 58 / 100 0 5 5
COLUMBUS 44 56 32 61 / 100 5 5 5
GAINESVILLE 38 48 31 53 / 100 5 5 10
MACON 46 56 29 60 / 100 20 5 5
ROME 36 46 27 57 / 100 0 5 5
PEACHTREE CITY 39 51 25 59 / 100 0 5 10
VIDALIA 49 63 32 63 / 90 60 5 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
1254 PM EST TUE JAN 17 2012
.PREV DISCUSSION... /ISSUED 940 AM EST TUE JAN 17 2012/
UPDATE...
A LINE OF SHOWERS WITH LIGHT TO MODERATE RAIN WAS OCCURRING AT THIS
TIME FROM CLARKESVILLE THROUGH CUMMING AND MARIETTA TO CARROLLTON.
THE LINE WAS AROUND 20 MILES WIDE AND MOVING EAST AT 40 MPH. HAVE
INCREASED THE POPS FOR THIS MORNING ACCORDINGLY FOR NORTH AND CENTRAL
GA. THE COLD FRONT OVER THE MS RIVER VALLEY WILL CONTINUE TO
APPROACH THE STATE TONIGHT. STILL LOOKING FOR ADDITIONAL SHOWERS AND
ISOLATED TSTMS TO DEVELOP IN ADVANCE OF THE FRONT LATER THIS
AFTERNOON AND EVENING. MOST MODELS SHOW A HIGH SHEAR BUT LOW
INSTABILITY ENVIRONMENT...SO SEVERE TSTMS IS UNLIKELY FOR GA.
OTHERWISE...NO OTHER CHANGES NEEDED FOR THE FIRST PERIOD.
16
PREV DISCUSSION... /ISSUED 651 AM EST TUE JAN 17 2012/
PREV DISCUSSION... /ISSUED 348 AM EST TUE JAN 17 2012/
SHORT TERM /TODAY THROUGH WEDNESDAY NIGHT/...
DEEP LAYER MOISTURE WILL INCREASE ACROSS THE CWA TODAY IN STRONG
SOUTHWESTERLY LOW LEVEL FLOW. THIS SHOULD RESULT IN INCREASING
COVERAGE OF SHOWERS AND A FEW THUNDERSTORMS. INSTABILITY IS
FORECAST TO BE MARGINAL...BUT SHEAR ASSOCIATED WITH STRONG 850MB
JET COULD SUPPORT ISOLATED STRONG THUNDERSTORMS MAINLY THIS
AFTERNOON AND EVENING. SURFACE COLD FRONT SHOULD CROSS THE CWA
TONIGHT WITH ONLY LINGERING SHOWERS EAST CENTRAL WEDNESDAY
MORNING. DRY AND COOL WEDNESDAY NIGHT. WITH WARM ADVECTION
TODAY...WILL FAVOR THE WARMER SIDE OF MAV/MET. OVERNIGHT LOWS ARE
TRICKY DUE TO TIMING OF COLD FRONTAL PASSAGE...BUT NORTHWEST ZONES
SHOULD SEE SOME LOW TO MID 30S BY WEDNESDAY MORNING. AT THIS
POINT...LOOKS LIKE RAIN SHOULD BE ENDING ACROSS THE EXTREME NORTH
BEFORE TEMPERATURES DROP INTO THE 30S.
LONG TERM /THURSDAY THROUGH MONDAY/...
MODELS AGREE ON A BRIEF DRY PERIOD THURSDAY AND THURSDAY NIGHT. A
WEAK SHORT WAVE MAY AFFECT THE NORTHWEST FRIDAY AND HAVE INCLUDED
LOW POPS. MODELS DIFFER ON LOCATION AND SPEED OF A COUPLE OF SHORT
WAVES THAT DEVELOP DURING THE WEEKEND SO HAVE LEFT CHANCE OR
SLIGHT CHANCE ACROSS THE AREA FOR SATURDAY AND SUNDAY. MORE
UNCERTAINTY FOR MONDAY WITH THE EVOLUTION OF A SOUTHERN STREAM
SHORT WAVE...SO HAVE KEPT CHANCE POPS IN FOR MONDAY.
HYDROLOGY...
RAINFALL TOTALS AVERAGING ONE HALF TO ONE INCH ACROSS THE COUNTY
WARNING AREA STILL LOOK REASONABLE. ISOLATED HIGHER AMOUNTS
POSSIBLE IN THUNDERSTORMS. NO FLOODING CONCERNS ARE ANTICIPATED.
&&
.AVIATION...
18Z UPDATE...
AS FIRST LINE OF SHRA HAS PUSHED THROUGH THE TERMINALS...LOW END
MVFR TO HIGH END IFR IS FILTERING IN QUICKLY. WILL CARRY THROUGH
FOR THE REMAINDER OF THE AFTERNOON UNTIL NEXT LINE OF SHRA WITH
EMBEDDED TSRA MOVES IN. LOOKS LIKE THE BEST CHANCES FOR TSRA WILL
BE FOR THE CSG TAF AND KEPT THE TEMPO IN FOR LATER THIS EVENING.
FOR THE REMAINDER OF THE SITES...23Z STILL LOOKS GOOD FOR ATL AREA
TERMINALS ALTHOUGH USING TIMING TOOLS...COULD BE A COUPLE HOURS
EITHER SIDE OF THIS. BASED ON HRRR OUTPUT AND CONSISTENCY
SAKE...JUST KEPT IT AT 23Z FOR NOW. WINDS SHOULD PICK UP OVERNIGHT
AND WILL SEE A QUICK TRANSITION FROM IFR TO MVFR AFTER 09Z. KEPT
MVFR THROUGH 12Z BEFORE SKC BECOMES PREDOMINANT FOR WED. WINDS
WILL BE GUSTY IN THE MORNING BUT SHOULD ACTUALLY DECREASE IN THE
AFTERNOON AS GRADIENT RELAXES.
//ATL CONFIDENCE...18Z UPDATE...
MEDIUM IN SHRA/TSRA TIMING.
HIGH FOR REMAINING ELEMENTS.
DEESE
&&
.PRELIMINARY POINT TEMPS/POPS...
ATHENS 62 43 53 28 / 70 80 5 5
ATLANTA 63 38 50 30 / 80 70 5 5
BLAIRSVILLE 58 33 45 25 / 90 60 5 5
CARTERSVILLE 63 35 47 24 / 100 60 5 5
COLUMBUS 68 47 53 30 / 70 80 10 5
GAINESVILLE 60 37 47 30 / 80 70 5 5
MACON 67 48 57 28 / 50 80 10 5
ROME 65 34 47 25 / 100 50 5 5
PEACHTREE CITY 64 37 51 23 / 80 80 5 5
VIDALIA 69 55 61 36 / 40 60 40 5
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
233 PM CST TUE JAN 17 2012
.DISCUSSION...
1243 PM CST
NO MAJOR CHANGES TO GOING FORECAST BUT HAVE PLAYED DOWN SNOW AMOUNTS
THROUGH THIS EVENING ACROSS NORTHERN ILLINOIS. PRIMARY AREA OF FGEN
FORCING IS NOW MOVING AWAY FROM THE FORECAST AREA WITH RADAR
INDICATING WEAKENING RETURNS. SECONDARY AREA OF SNOWFALL ASSOCIATED
WITH H5 VORT MOVING EAST ACROSS THE RIVER ALSO SHOWING WEAKENING
RETURNS...WITH WFO DAVENPORT REPORTING ONLY A COUPLE TENTHS OVER
LAST 6 HOURS...AND OBSERVER NEAR DBQ COMING IN AT 1.6 INCHES FOR SAME
PERIOD. HAVE HAD SEVERAL REPORTS FROM EARLIER THIS MORNING
SUGGESTING SNOWFALL ALREADY AROUND 3 INCHES ACROSS FAR NORTHWEST
PORTION OF CWA...BUT ONLY EXPECT ADDITIONAL SNOW OF AROUND AN INCH
OVER THESE AREAS...WITH...ON THE HIGH SIDE...PERHAPS LOCALIZED
AMOUNTS AROUND 2 INCHES. MORE REALISTICALLY THOUGH...NEW
ACCUMULATION THROUGH THE REMAINDER OF AFTERNOON WILL LIKELY BE UP
TO AN INCH ACROSS THE NORTH...WITH PERHAPS A DUSTING SOUTH OF THE
I-88 CORRIDOR...AND NO ACCUMULATION SOUTH OF THE I-80 CORRIDOR.
AREAS THAT SEE LIGHT ACCUMULATIONS WILL ALSO HAVE TO DEAL WITH
BLOWING AND DRIFTING SNOW AS WINDS CONTINUE TO GUST AROUND AND
ABOVE 30 MPH THIS AFTERNOON. BMD
//PREV DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LIGHT SNOW CONTINUING THROUGH THE AFTERNOON...ADDITIONAL DUSTING
TO PERHAPS A FEW TENTHS ACCUMULATION.
* VARIABLE VISIBILITY POSSIBLY AS LOW AS 2SM FOR SHORT PERIODS BUT
MAINLY IN THE 3-6SM RANGE
* SNOW ENDING TOWARD 00-01Z.
* MVFR CIGS WITH VARIABLE BASE HEIGHTS CONTINUING THEN SCATTERING
EARLY EVENING.
* NORTHWEST WINDS GUSTING TO 25-30 KT THRU AFTERNOON...THEN
DIMINISHING THIS EVENING.NOON.
MDB
//DISCUSSION...UPDATED 20Z...
RADAR HAS BEEN SHOWING A DOWNWARD TREND IN REFLECTIVITY INTENSITY
OVER THE LAST HOUR OR SO AS BETTER AREA OF SNOW MOVES ACROSS THE
TERMINALS. LIGHT SNOW WILL CONTINUE BUT VISIBILITY REDUCTION HAS
NOT BEEN AS SIGNIFICANT. EXPECT GENERALLY MVFR VSBY WITH BRIEF
DROPS TO AROUND 1 SM POSSIBLE UNDER BETTER SHOW SHOWERS. SNOW WILL
END FROM WEST TO EAST INTO EARLY EVENING WITH SKIES THEN CLEARING
INTO MID EVENING.
MDB
FROM 18Z...
HAVE MADE SOME ADJUSTMENTS TO THE FORECAST IN TERMS OF
VSBY/SNOWFALL. OVERALL RFD WILL SEE THE MOST PERSISTENT SNOWFALL
AND LOWEST CONDITIONS. LATEST OBSERVED TRENDS SHOW A BIT OF A LULL
IN SNOW INTENSITY AND SOME IMPROVEMENT TO VSBY OCCURRING FROM ORD
BACK TO VYS. SO CHI AREA TERMINALS AND GYY WILL PROBABLY SEE A
BRIEF PERIOD OF IMPROVEMENT NEXT 1-2 HOURS. THE MAIN UPPER TROUGH
IS MOVING EASTWARD ACROSS CENTRAL/EASTERN IOWA WHICH WILL BRING
STEADIER SNOW BACK TO THE AREA THIS AFTERNOON. GENERALLY EXPECT
VSBY AROUND 2SM IN LIGHT SNOW TO RETURN TO THE CHI TERMINALS AND
GYY AND CONTINUE FOR SEVERAL HOURS BEFORE ENDING. MAY SEE SOME
VSBY DOWN TO ABOUT A MILE AS WELL. WITH TEMPERATURES FALLING
ACCUMULATION WILL BECOME MORE LIKELY BUT THE STRONG NORTHWEST
WINDS GUSTING IN THE 25-30 KT RANGE WILL BLOW THE SNOW AROUND.
CIGS SHOULD STAY MVFR BUT BASE HEIGHT WILL LIKELY VARY.
SNOW WILL EXIT TO THE EAST LATE THIS AFTERNOON/EARLY THIS EVENING
AND THE END TIME IN THE TAF MAY NEED TO BE TWEAKED. CIGS LOOK TO
QUICKLY SCATTER/CLEAR EARLY THIS EVENING LEAVING VFR OVERNIGHT
WITH VERY COLD CONDITIONS. HIGH PRESSURE WILL MOVE ACROSS THE AREA
OVERNIGHT AND WEDNESDAY MORNING ALLOWING WINDS TO DIMINISH THIS
EVENING THEN TURN SOUTHWEST AND BECOME LIGHT OVERNIGHT. SPEEDS
WILL INCREASE FROM THE SOUTH-SOUTHWEST THROUGH THE DAY WITH MID
AND HIGH CLOUDS INCREASING DURING THE AFTERNOON AHEAD OF A CLIPPER
SYSTEM MOVING NORTH OF THE AREA.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN LIGHT SNOW CONTINUING THROUGH AFTERNOON.
* MEDIUM-HIGH CONFIDENCE IN STEADIER LIGHT SNOW ARRIVING BY MID
AFTERNOON WITH ACCUMULATION POSSIBLE.
* HIGH CONFIDENCE IN VARIABLE VISIBILITY IN LIGHT SNOW AND THAT
ANY VSBY AROUND 2SM WOULD BE BRIEF.
* MEDIUM CONFIDENCE IN SPECIFIC END TIME OF SNOW.
* HIGH CONFIDENCE IN MVFR CIGS CONTINUING INTO EARLY EVENING THEN
SCATTERING.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...SLIGHT CHANCE OF SNOW. GUSTY SOUTHWEST WINDS
SHIFTING WESTERLY BY MORNING.
* THURSDAY...SLIGHT CHANCE OF SNOW EARLY. GUSTY NORTHWEST WINDS.
* FRIDAY...SNOW. IFR CIGS. LIFR VIS.
* SATURDAY...VFR.
* SUNDAY...VFR. SLIGHT CHANCE OF RAIN LATE.
* MONDAY...CHANCE OF RAIN. MVFR POSSIBLE. CMS
&&
.MARINE...
231 PM CST
THE VERY PROGRESSIVE PATTERN WILL CONTINUE TO AFFECT LAKE MICHIGAN
FOR THE NEXT SEVERAL DAYS.
NORTH TO NORTHWEST GALES SHOULD PERSIST OVER THE LAKE THROUGH THE
EVENING AS DEEPENING LOW PRESSURE TRACKS FROM NEAR DETROIT TO
SOUTHERN QUEBEC TONIGHT. A RIDGE OF HIGH PRESSURE WILL BUILD ACROSS
THE UPPER MIDWEST AND INTO THE WESTERN GREAT LAKES REGION LATE
TONIGHT...ALLOWING WINDS TO SUBSIDE...BUT WAVES SHOULD REMAIN HIGH
OVER THE SOUTHERN PORTIONS OF THE LAKE INTO WEDNESDAY BEFORE
SETTLING DOWN BELOW SMALL CRAFT ADVISORY LEVELS. HOWEVER...THE
PERIOD OF TIME WITHOUT A MARINE HAZARD HEADLINE WILL BE BRIEF AS
ANOTHER DEEPENING LOW PRESSURE SYSTEM DROPS OUT OF THE NORTHERN
ROCKIES AND MOVES INTO THE WESTERN GREAT LAKES WEDNESDAY NIGHT.
INCREASING SOUTHERLY WINDS ARE EXPECTED AHEAD OF THIS LOW...AND
SINCE THE HIGH WILL BE SLOW TO MOVE OFF TO THE EAST...THE RESULTANT
STRONG PRESSURE GRADIENT MAY LEAD TO MORE GALES OVER THE LAKE. THE
LOW WILL DRAG A COLD FRONT ACROSS THE LAKE LATE WEDNESDAY NIGHT OR
EARLY THURSDAY MORNING...AND THE PUSH OF COLD AIR BEHIND THE FRONT
WILL LIKELY KEEP GALES GOING INTO THURSDAY AFTERNOON. A SLOWER
MOVING HIGH PRESSURE SYSTEM SHOULD THEN BUILD ACROSS THE UPPER
MISSISSIPPI VALLEY INTO THE OHIO VALLEY LATE THIS WEEK AND INTO THE
WEEKEND.
KREIN
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006 UNTIL 9 PM
TUESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
212 PM CST TUE JAN 17 2012
.DISCUSSION...
1243 PM CST
NO MAJOR CHANGES TO GOING FORECAST BUT HAVE PLAYED DOWN SNOW AMOUNTS
THROUGH THIS EVENING ACROSS NORTHERN ILLINOIS. PRIMARY AREA OF FGEN
FORCING IS NOW MOVING AWAY FROM THE FORECAST AREA WITH RADAR
INDICATING WEAKENING RETURNS. SECONDARY AREA OF SNOWFALL ASSOCIATED
WITH H5 VORT MOVING EAST ACROSS THE RIVER ALSO SHOWING WEAKENING
RETURNS...WITH WFO DAVENPORT REPORTING ONLY A COUPLE TENTHS OVER
LAST 6 HOURS...AND OBSERVER NEAR DBQ COMING IN AT 1.6 INCHES FOR SAME
PERIOD. HAVE HAD SEVERAL REPORTS FROM EARLIER THIS MORNING
SUGGESTING SNOWFALL ALREADY AROUND 3 INCHES ACROSS FAR NORTHWEST
PORTION OF CWA...BUT ONLY EXPECT ADDITIONAL SNOW OF AROUND AN INCH
OVER THESE AREAS...WITH...ON THE HIGH SIDE...PERHAPS LOCALIZED
AMOUNTS AROUND 2 INCHES. MORE REALISTICALLY THOUGH...NEW
ACCUMULATION THROUGH THE REMAINDER OF AFTERNOON WILL LIKELY BE UP
TO AN INCH ACROSS THE NORTH...WITH PERHAPS A DUSTING SOUTH OF THE
I-88 CORRIDOR...AND NO ACCUMULATION SOUTH OF THE I-80 CORRIDOR.
AREAS THAT SEE LIGHT ACCUMULATIONS WILL ALSO HAVE TO DEAL WITH
BLOWING AND DRIFTING SNOW AS WINDS CONTINUE TO GUST AROUND AND
ABOVE 30 MPH THIS AFTERNOON. BMD
//PREV DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 20Z...
* LIGHT SNOW CONTINUING THROUGH THE AFTERNOON...ADDITIONAL DUSTING
TO PERHAPS A FEW TENTHS ACCUMULATION.
* VARIABLE VISIBILITY POSSIBLY AS LOW AS 2SM FOR SHORT PERIODS BUT
MAINLY IN THE 3-6SM RANGE
* SNOW ENDING TOWARD 00-01Z.
* MVFR CIGS WITH VARIABLE BASE HEIGHTS CONTINUING THEN SCATTERING
EARLY EVENING.
* NORTHWEST WINDS GUSTING TO 25-30 KT THRU AFTERNOON...THEN
DIMINISHING THIS EVENING.NOON.
MDB
//DISCUSSION...UPDATED 20Z...
RADAR HAS BEEN SHOWING A DOWNWARD TREND IN REFLECTIVITY INTENSITY
OVER THE LAST HOUR OR SO AS BETTER AREA OF SNOW MOVES ACROSS THE
TERMINALS. LIGHT SNOW WILL CONTINUE BUT VISIBILITY REDUCTION HAS
NOT BEEN AS SIGNIFICANT. EXPECT GENERALLY MVFR VSBY WITH BRIEF
DROPS TO AROUND 1 SM POSSIBLE UNDER BETTER SHOW SHOWERS. SNOW WILL
END FROM WEST TO EAST INTO EARLY EVENING WITH SKIES THEN CLEARING
INTO MID EVENING.
MDB
FROM 18Z...
HAVE MADE SOME ADJUSTMENTS TO THE FORECAST IN TERMS OF
VSBY/SNOWFALL. OVERALL RFD WILL SEE THE MOST PERSISTENT SNOWFALL
AND LOWEST CONDITIONS. LATEST OBSERVED TRENDS SHOW A BIT OF A LULL
IN SNOW INTENSITY AND SOME IMPROVEMENT TO VSBY OCCURRING FROM ORD
BACK TO VYS. SO CHI AREA TERMINALS AND GYY WILL PROBABLY SEE A
BRIEF PERIOD OF IMPROVEMENT NEXT 1-2 HOURS. THE MAIN UPPER TROUGH
IS MOVING EASTWARD ACROSS CENTRAL/EASTERN IOWA WHICH WILL BRING
STEADIER SNOW BACK TO THE AREA THIS AFTERNOON. GENERALLY EXPECT
VSBY AROUND 2SM IN LIGHT SNOW TO RETURN TO THE CHI TERMINALS AND
GYY AND CONTINUE FOR SEVERAL HOURS BEFORE ENDING. MAY SEE SOME
VSBY DOWN TO ABOUT A MILE AS WELL. WITH TEMPERATURES FALLING
ACCUMULATION WILL BECOME MORE LIKELY BUT THE STRONG NORTHWEST
WINDS GUSTING IN THE 25-30 KT RANGE WILL BLOW THE SNOW AROUND.
CIGS SHOULD STAY MVFR BUT BASE HEIGHT WILL LIKELY VARY.
SNOW WILL EXIT TO THE EAST LATE THIS AFTERNOON/EARLY THIS EVENING
AND THE END TIME IN THE TAF MAY NEED TO BE TWEAKED. CIGS LOOK TO
QUICKLY SCATTER/CLEAR EARLY THIS EVENING LEAVING VFR OVERNIGHT
WITH VERY COLD CONDITIONS. HIGH PRESSURE WILL MOVE ACROSS THE AREA
OVERNIGHT AND WEDNESDAY MORNING ALLOWING WINDS TO DIMINISH THIS
EVENING THEN TURN SOUTHWEST AND BECOME LIGHT OVERNIGHT. SPEEDS
WILL INCREASE FROM THE SOUTH-SOUTHWEST THROUGH THE DAY WITH MID
AND HIGH CLOUDS INCREASING DURING THE AFTERNOON AHEAD OF A CLIPPER
SYSTEM MOVING NORTH OF THE AREA.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 20Z...
* HIGH CONFIDENCE IN LIGHT SNOW CONTINUING THROUGH AFTERNOON.
* MEDIUM-HIGH CONFIDENCE IN STEADIER LIGHT SNOW ARRIVING BY MID
AFTERNOON WITH ACCUMULATION POSSIBLE.
* HIGH CONFIDENCE IN VARIABLE VISIBILITY IN LIGHT SNOW AND THAT
ANY VSBY AROUND 2SM WOULD BE BRIEF.
* MEDIUM CONFIDENCE IN SPECIFIC END TIME OF SNOW.
* HIGH CONFIDENCE IN MVFR CIGS CONTINUING INTO EARLY EVENING THEN
SCATTERING.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...SLIGHT CHANCE OF SNOW. GUSTY SOUTHWEST WINDS
SHIFTING WESTERLY BY MORNING.
* THURSDAY...SLIGHT CHANCE OF SNOW EARLY. GUSTY NORTHWEST WINDS.
* FRIDAY...SNOW. IFR CIGS. LIFR VIS.
* SATURDAY...VFR.
* SUNDAY...VFR. SLIGHT CHANCE OF RAIN LATE.
* MONDAY...CHANCE OF RAIN. MVFR POSSIBLE. CMS
&&
.MARINE...
254 AM CST
LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL
QUEBEC...WITH A TRAILING AND NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING SOUTHWEST THROUGH NORTHWEST IN/CENTRAL IL. A SERIES OF
WEAK LOW PRESSURE HAVE MOVED ALONG THIS BOUNDARY...HOWEVER GUIDANCE
IS INDICATING THAT TODAY THE BOUNDARY WILL BEGIN TO ADVANCE
EAST/SOUTHEAST AS A PUSH OF MUCH COLDER AIR ARRIVES. EARLY THIS
MORNING OBSERVATIONS HAVE INDICATED WIND GUSTS BETWEEN 10 TO 20 KT
GENERALLY FROM THE NORTH. WITH THE LACK OF A SIGNIFICANT PRESSURE
GRADIENT EARLY THIS MORNING WINDS SHOULD REMAIN LIGHT FOR A BRIEF
PERIOD OF TIME...BEFORE STEADILY RAMPING UP TOWARDS GALES FOR THE
OPEN WATERS AND SOLID SMALL CRAFT CONDITIONS FOR THE NEARSHORE
WATERS.
GUIDANCE HAS CONTINUED TO FOCUS ON A 15-18Z WINDOW FOR WINDS PUSHING
TO 35-40KT ACROSS THE OPEN WATERS OF LAKE MICHIGAN. SREF NEAR SFC
WIND PLUMES HAVE SUGGESTED WINDS AT 18Z WILL BE SUSTAINED ARND 20KT.
THIS COUPLED WITH A HIGH CONFIDENCE OF THE MIXED LAYER BRINGING TO
THE SFC WINDS ARND 850MB OF 40-45KT...SUGGEST HEAVILY THAT GALES
CONFIDENCE IS NEAR 100 PERCENT. THEN BASED ON OPERATIONAL MODELS AND
ENSEMBLES WINDS RAPIDLY DECLINE BY 06Z WED TO ARND 10-20KT
SUSTAINED...AND GUSTS TO 30KT. THIS SHOULD BRING AN END TO THE
GALES...HOWEVER INFREQUENT GALES TO 35KT MAY OCCUR FOR A FEW HOURS
AFT 06Z WED. SMALL CRAFT CONDITIONS WILL PERSIST FOR THE NORTHWEST
INDIANA WATERS THROUGH WED MORNING UNDER A NW FLOW AND ELEVATED
WAVES.
HIGH PRESSURE QUICKLY BUILDS IN FROM THE WEST/SOUTHWEST...AND SHOULD
RELAX WINDS FOR THE REMAINDER OF THE NIGHT INTO EARLY WED. THEN YET
ANOTHER SYSTEM IS PROGGED TO DEVELOP WED NGT AS THE HIGH PRESSURE
DRIFTS EAST. THIS WILL ALLOW A TIGHTENING PRESSURE GRADIENT LATE WED
AS WINDS BACK TO THE SOUTHWEST. CURRENT INDICATIONS ARE THAT LOW END
GALES ARE POSSIBLE EARLY THUR MORNING. THEN A BROAD HIGH PRESSURE
AREA BUILDS IN FROM THE NW AND SHUD PROVIDE A PERIOD OF LIGHTER
WINDS FOR FRI. THEN WINDS SHUD QUIET DOWN FOR A FEW PERIODS. THEN
FOR THE SECOND HALF OF THE UPCOMING WEEKEND...MUCH WARMER AIR MAY
SLIDE OVER LAKE MICHIGAN SUN. THIS HAS THE POTENTIAL OF CREATING A
RARE LATE JANUARY STABLE MARINE ENVIRONMENT SUN. CONFIDENCE AT THIS
JUNCTURE IS VERY LOW...HOWEVER SOME CONSISTENCY HAS BEEN NOTED
AMONGST FORECAST SOLUTIONS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006 UNTIL 9 PM
TUESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1247 PM CST TUE JAN 17 2012
.DISCUSSION...
1243 PM CST
NO MAJOR CHANGES TO GOING FORECAST BUT HAVE PLAYED DOWN SNOW AMOUNTS
THROUGH THIS EVENING ACROSS NORTHERN ILLINOIS. PRIMARY AREA OF FGEN
FORCING IS NOW MOVING AWAY FROM THE FORECAST AREA WITH RADAR
INDICATING WEAKENING RETURNS. SECONDARY AREA OF SNOWFALL ASSOCIATED
WITH H5 VORT MOVING EAST ACROSS THE RIVER ALSO SHOWING WEAKENING
RETURNS...WITH WFO DAVENPORT REPORTING ONLY A COUPLE TENTHS OVER
LAST 6 HOURS...AND OBSERVER NEAR DBQ COMING IN AT 1.6 INCHES FOR SAME
PERIOD. HAVE HAD SEVERAL REPORTS FROM EARLIER THIS MORNING
SUGGESTING SNOWFALL ALREADY AROUND 3 INCHES ACROSS FAR NORTHWEST
PORTION OF CWA...BUT ONLY EXPECT ADDITIONAL SNOW OF AROUND AN INCH
OVER THESE AREAS...WITH...ON THE HIGH SIDE...PERHAPS LOCALIZED
AMOUNTS AROUND 2 INCHES. MORE REALISTICALLY THOUGH...NEW
ACCUMULATION THROUGH THE REMAINDER OF AFTERNOON WILL LIKELY BE UP
TO AN INCH ACROSS THE NORTH...WITH PERHAPS A DUSTING SOUTH OF THE
I-88 CORRIDOR...AND NO ACCUMULATION SOUTH OF THE I-80 CORRIDOR.
AREAS THAT SEE LIGHT ACCUMULATIONS WILL ALSO HAVE TO DEAL WITH
BLOWING AND DRIFTING SNOW AS WINDS CONTINUE TO GUST AROUND AND
ABOVE 30 MPH THIS AFTERNOON. BMD
&&
.PREV DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LIGHT SNOW CONTINUING THROUGH THE AFTERNOON.
* PERIOD OF MORE INTENSE ACCUMULATING SNOW POSSIBLE MID
AFTERNOON.
* SHORT PERIOD OF BETTER VISIBILITY NOW WITH DECREASE BACK TO
AROUND 2SM TOWARD 19-20Z...POSSIBLY AS LOW AS 1SM AT TIMES.
* SNOW WINDS DOWN TOWARD 00-01Z.
* MVFR CIGS WITH VARIABLE BASE HEIGHTS CONTINUING THEN SCATTERING
EARLY EVENING.
* NORTHWEST WINDS GUSTING TO 25-30 KT THRU AFTERNOON...THEN
DIMINISHING THIS EVENING.
* BLOWING SNOW WITH ANY ACCUMULATION THIS AFTERNOON.
MDB
//DISCUSSION...UPDATED 18Z...
HAVE MADE SOME ADJUSTMENTS TO THE FORECAST IN TERMS OF
VSBY/SNOWFALL. OVERALL RFD WILL SEE THE MOST PERSISTENT SNOWFALL
AND LOWEST CONDITIONS. LATEST OBSERVED TRENDS SHOW A BIT OF A LULL
IN SNOW INTENSITY AND SOME IMPROVEMENT TO VSBY OCCURRING FROM ORD
BACK TO VYS. SO CHI AREA TERMINALS AND GYY WILL PROBABLY SEE A
BRIEF PERIOD OF IMPROVEMENT NEXT 1-2 HOURS. THE MAIN UPPER TROUGH
IS MOVING EASTWARD ACROSS CENTRAL/EASTERN IOWA WHICH WILL BRING
STEADIER SNOW BACK TO THE AREA THIS AFTERNOON. GENERALLY EXPECT
VSBY AROUND 2SM IN LIGHT SNOW TO RETURN TO THE CHI TERMINALS AND
GYY AND CONTINUE FOR SEVERAL HOURS BEFORE ENDING. MAY SEE SOME
VSBY DOWN TO ABOUT A MILE AS WELL. WITH TEMPERATURES FALLING
ACCUMULATION WILL BECOME MORE LIKELY BUT THE STRONG NORTHWEST
WINDS GUSTING IN THE 25-30 KT RANGE WILL BLOW THE SNOW AROUND.
CIGS SHOULD STAY MVFR BUT BASE HEIGHT WILL LIKELY VARY.
SNOW WILL EXIT TO THE EAST LATE THIS AFTERNOON/EARLY THIS EVENING
AND THE END TIME IN THE TAF MAY NEED TO BE TWEAKED. CIGS LOOK TO
QUICKLY SCATTER/CLEAR EARLY THIS EVENING LEAVING VFR OVERNIGHT
WITH VERY COLD CONDITIONS. HIGH PRESSURE WILL MOVE ACROSS THE AREA
OVERNIGHT AND WEDNESDAY MORNING ALLOWING WINDS TO DIMINISH THIS
EVENING THEN TURN SOUTHWEST AND BECOME LIGHT OVERNIGHT. SPEEDS
WILL INCREASE FROM THE SOUTH-SOUTHWEST THROUGH THE DAY WITH MID
AND HIGH CLOUDS INCREASING DURING THE AFTERNOON AHEAD OF A CLIPPER
SYSTEM MOVING NORTH OF THE AREA.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN LIGHT SNOW CONTINUING THROUGH AFTERNOON.
* MEDIUM-HIGH CONFIDENCE IN STEADIER LIGHT SNOW ARRIVING BY MID
AFTERNOON WITH ACCUMULATION POSSIBLE.
* HIGH CONFIDENCE IN BETTER VISIBILITY NEXT HOUR OR 2 WITH MEDIUM-
HIGH CONFIDENCE IN VSBY FALLING TOWARD 19-20 AS SNOW INCREASES
...LOW-MEDIUM CONFIDENCE IN SPECIFIC VSBY VALUES MID AFTERNOON IN
BETTER SNOW.
* MEDIUM CONFIDENCE IN END TIME OF SNOW.
* HIGH CONFIDENCE IN MVFR CIGS CONTINUING INTO EARLY EVENING THEN
SCATTERING.
* HIGH CONFIDENCE THAT AT LEAST SOME BLOWING SNOW WILL OCCUR WITH
ANY ACCUMULATING SNOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...SLIGHT CHANCE OF SNOW. GUSTY SOUTHWEST WINDS
SHIFTING WESTERLY BY MORNING.
* THURSDAY...SLIGHT CHANCE OF SNOW EARLY. GUSTY NORTHWEST WINDS.
* FRIDAY...SNOW. IFR CIGS. LIFR VIS.
* SATURDAY...VFR.
* SUNDAY...VFR. SLIGHT CHANCE OF RAIN LATE.
* MONDAY...CHANCE OF RAIN. MVFR POSSIBLE. CMS
&&
.MARINE...
254 AM CST
LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL
QUEBEC...WITH A TRAILING AND NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING SOUTHWEST THROUGH NORTHWEST IN/CENTRAL IL. A SERIES OF
WEAK LOW PRESSURE HAVE MOVED ALONG THIS BOUNDARY...HOWEVER GUIDANCE
IS INDICATING THAT TODAY THE BOUNDARY WILL BEGIN TO ADVANCE
EAST/SOUTHEAST AS A PUSH OF MUCH COLDER AIR ARRIVES. EARLY THIS
MORNING OBSERVATIONS HAVE INDICATED WIND GUSTS BETWEEN 10 TO 20 KT
GENERALLY FROM THE NORTH. WITH THE LACK OF A SIGNIFICANT PRESSURE
GRADIENT EARLY THIS MORNING WINDS SHOULD REMAIN LIGHT FOR A BRIEF
PERIOD OF TIME...BEFORE STEADILY RAMPING UP TOWARDS GALES FOR THE
OPEN WATERS AND SOLID SMALL CRAFT CONDITIONS FOR THE NEARSHORE
WATERS.
GUIDANCE HAS CONTINUED TO FOCUS ON A 15-18Z WINDOW FOR WINDS PUSHING
TO 35-40KT ACROSS THE OPEN WATERS OF LAKE MICHIGAN. SREF NEAR SFC
WIND PLUMES HAVE SUGGESTED WINDS AT 18Z WILL BE SUSTAINED ARND 20KT.
THIS COUPLED WITH A HIGH CONFIDENCE OF THE MIXED LAYER BRINGING TO
THE SFC WINDS ARND 850MB OF 40-45KT...SUGGEST HEAVILY THAT GALES
CONFIDENCE IS NEAR 100 PERCENT. THEN BASED ON OPERATIONAL MODELS AND
ENSEMBLES WINDS RAPIDLY DECLINE BY 06Z WED TO ARND 10-20KT
SUSTAINED...AND GUSTS TO 30KT. THIS SHOULD BRING AN END TO THE
GALES...HOWEVER INFREQUENT GALES TO 35KT MAY OCCUR FOR A FEW HOURS
AFT 06Z WED. SMALL CRAFT CONDITIONS WILL PERSIST FOR THE NORTHWEST
INDIANA WATERS THROUGH WED MORNING UNDER A NW FLOW AND ELEVATED
WAVES.
HIGH PRESSURE QUICKLY BUILDS IN FROM THE WEST/SOUTHWEST...AND SHOULD
RELAX WINDS FOR THE REMAINDER OF THE NIGHT INTO EARLY WED. THEN YET
ANOTHER SYSTEM IS PROGGED TO DEVELOP WED NGT AS THE HIGH PRESSURE
DRIFTS EAST. THIS WILL ALLOW A TIGHTENING PRESSURE GRADIENT LATE WED
AS WINDS BACK TO THE SOUTHWEST. CURRENT INDICATIONS ARE THAT LOW END
GALES ARE POSSIBLE EARLY THUR MORNING. THEN A BROAD HIGH PRESSURE
AREA BUILDS IN FROM THE NW AND SHUD PROVIDE A PERIOD OF LIGHTER
WINDS FOR FRI. THEN WINDS SHUD QUIET DOWN FOR A FEW PERIODS. THEN
FOR THE SECOND HALF OF THE UPCOMING WEEKEND...MUCH WARMER AIR MAY
SLIDE OVER LAKE MICHIGAN SUN. THIS HAS THE POTENTIAL OF CREATING A
RARE LATE JANUARY STABLE MARINE ENVIRONMENT SUN. CONFIDENCE AT THIS
JUNCTURE IS VERY LOW...HOWEVER SOME CONSISTENCY HAS BEEN NOTED
AMONGST FORECAST SOLUTIONS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006 UNTIL 9 PM
TUESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1207 PM CST TUE JAN 17 2012
.DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 18Z...
* LIGHT SNOW CONTINUING THROUGH THE AFTERNOON.
* PERIOD OF MORE INTENSE ACCUMULATING SNOW POSSIBLE MID
AFTERNOON.
* SHORT PERIOD OF BETTER VISIBILITY NOW WITH DECREASE BACK TO
AROUND 2SM TOWARD 19-20Z...POSSIBLY AS LOW AS 1SM AT TIMES.
* SNOW WINDS DOWN TOWARD 00-01Z.
* MVFR CIGS WITH VARIABLE BASE HEIGHTS CONTINUING THEN SCATTERING
EARLY EVENING.
* NORTHWEST WINDS GUSTING TO 25-30 KT THRU AFTERNOON...THEN
DIMINISHING THIS EVENING.
* BLOWING SNOW WITH ANY ACCUMULATION THIS AFTERNOON.
MDB
//DISCUSSION...UPDATED 18Z...
HAVE MADE SOME ADJUSTMENTS TO THE FORECAST IN TERMS OF
VSBY/SNOWFALL. OVERALL RFD WILL SEE THE MOST PERSISTENT SNOWFALL
AND LOWEST CONDITIONS. LATEST OBSERVED TRENDS SHOW A BIT OF A LULL
IN SNOW INTENSITY AND SOME IMPROVEMENT TO VSBY OCCURRING FROM ORD
BACK TO VYS. SO CHI AREA TERMINALS AND GYY WILL PROBABLY SEE A
BRIEF PERIOD OF IMPROVEMENT NEXT 1-2 HOURS. THE MAIN UPPER TROUGH
IS MOVING EASTWARD ACROSS CENTRAL/EASTERN IOWA WHICH WILL BRING
STEADIER SNOW BACK TO THE AREA THIS AFTERNOON. GENERALLY EXPECT
VSBY AROUND 2SM IN LIGHT SNOW TO RETURN TO THE CHI TERMINALS AND
GYY AND CONTINUE FOR SEVERAL HOURS BEFORE ENDING. MAY SEE SOME
VSBY DOWN TO ABOUT A MILE AS WELL. WITH TEMPERATURES FALLING
ACCUMULATION WILL BECOME MORE LIKELY BUT THE STRONG NORTHWEST
WINDS GUSTING IN THE 25-30 KT RANGE WILL BLOW THE SNOW AROUND.
CIGS SHOULD STAY MVFR BUT BASE HEIGHT WILL LIKELY VARY.
SNOW WILL EXIT TO THE EAST LATE THIS AFTERNOON/EARLY THIS EVENING
AND THE END TIME IN THE TAF MAY NEED TO BE TWEAKED. CIGS LOOK TO
QUICKLY SCATTER/CLEAR EARLY THIS EVENING LEAVING VFR OVERNIGHT
WITH VERY COLD CONDITIONS. HIGH PRESSURE WILL MOVE ACROSS THE AREA
OVERNIGHT AND WEDNESDAY MORNING ALLOWING WINDS TO DIMINISH THIS
EVENING THEN TURN SOUTHWEST AND BECOME LIGHT OVERNIGHT. SPEEDS
WILL INCREASE FROM THE SOUTH-SOUTHWEST THROUGH THE DAY WITH MID
AND HIGH CLOUDS INCREASING DURING THE AFTERNOON AHEAD OF A CLIPPER
SYSTEM MOVING NORTH OF THE AREA.
MDB
//ORD AND MDW CONFIDENCE...UPDATED 18Z...
* HIGH CONFIDENCE IN LIGHT SNOW CONTINUING THROUGH AFTERNOON.
* MEDIUM-HIGH CONFIDENCE IN STEADIER LIGHT SNOW ARRIVING BY MID
AFTERNOON WITH ACCUMULATION POSSIBLE.
* HIGH CONFIDENCE IN BETTER VISIBILITY NEXT HOUR OR 2 WITH MEDIUM-
HIGH CONFIDENCE IN VSBY FALLING TOWARD 19-20 AS SNOW INCREASES
...LOW-MEDIUM CONFIDENCE IN SPECIFIC VSBY VALUES MID AFTERNOON IN
BETTER SNOW.
* MEDIUM CONFIDENCE IN END TIME OF SNOW.
* HIGH CONFIDENCE IN MVFR CIGS CONTINUING INTO EARLY EVENING THEN
SCATTERING.
* HIGH CONFIDENCE THAT AT LEAST SOME BLOWING SNOW WILL OCCUR WITH
ANY ACCUMULATING SNOW.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...SLIGHT CHANCE OF SNOW. GUSTY SOUTHWEST WINDS
SHIFTING WESTERLY BY MORNING.
* THURSDAY...SLIGHT CHANCE OF SNOW EARLY. GUSTY NORTHWEST WINDS.
* FRIDAY...SNOW. IFR CIGS. LIFR VIS.
* SATURDAY...VFR.
* SUNDAY...VFR. SLIGHT CHANCE OF RAIN LATE.
* MONDAY...CHANCE OF RAIN. MVFR POSSIBLE. CMS
&&
.MARINE...
254 AM CST
LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL
QUEBEC...WITH A TRAILING AND NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING SOUTHWEST THROUGH NORTHWEST IN/CENTRAL IL. A SERIES OF
WEAK LOW PRESSURE HAVE MOVED ALONG THIS BOUNDARY...HOWEVER GUIDANCE
IS INDICATING THAT TODAY THE BOUNDARY WILL BEGIN TO ADVANCE
EAST/SOUTHEAST AS A PUSH OF MUCH COLDER AIR ARRIVES. EARLY THIS
MORNING OBSERVATIONS HAVE INDICATED WIND GUSTS BETWEEN 10 TO 20 KT
GENERALLY FROM THE NORTH. WITH THE LACK OF A SIGNIFICANT PRESSURE
GRADIENT EARLY THIS MORNING WINDS SHOULD REMAIN LIGHT FOR A BRIEF
PERIOD OF TIME...BEFORE STEADILY RAMPING UP TOWARDS GALES FOR THE
OPEN WATERS AND SOLID SMALL CRAFT CONDITIONS FOR THE NEARSHORE
WATERS.
GUIDANCE HAS CONTINUED TO FOCUS ON A 15-18Z WINDOW FOR WINDS PUSHING
TO 35-40KT ACROSS THE OPEN WATERS OF LAKE MICHIGAN. SREF NEAR SFC
WIND PLUMES HAVE SUGGESTED WINDS AT 18Z WILL BE SUSTAINED ARND 20KT.
THIS COUPLED WITH A HIGH CONFIDENCE OF THE MIXED LAYER BRINGING TO
THE SFC WINDS ARND 850MB OF 40-45KT...SUGGEST HEAVILY THAT GALES
CONFIDENCE IS NEAR 100 PERCENT. THEN BASED ON OPERATIONAL MODELS AND
ENSEMBLES WINDS RAPIDLY DECLINE BY 06Z WED TO ARND 10-20KT
SUSTAINED...AND GUSTS TO 30KT. THIS SHOULD BRING AN END TO THE
GALES...HOWEVER INFREQUENT GALES TO 35KT MAY OCCUR FOR A FEW HOURS
AFT 06Z WED. SMALL CRAFT CONDITIONS WILL PERSIST FOR THE NORTHWEST
INDIANA WATERS THROUGH WED MORNING UNDER A NW FLOW AND ELEVATED
WAVES.
HIGH PRESSURE QUICKLY BUILDS IN FROM THE WEST/SOUTHWEST...AND SHOULD
RELAX WINDS FOR THE REMAINDER OF THE NIGHT INTO EARLY WED. THEN YET
ANOTHER SYSTEM IS PROGGED TO DEVELOP WED NGT AS THE HIGH PRESSURE
DRIFTS EAST. THIS WILL ALLOW A TIGHTENING PRESSURE GRADIENT LATE WED
AS WINDS BACK TO THE SOUTHWEST. CURRENT INDICATIONS ARE THAT LOW END
GALES ARE POSSIBLE EARLY THUR MORNING. THEN A BROAD HIGH PRESSURE
AREA BUILDS IN FROM THE NW AND SHUD PROVIDE A PERIOD OF LIGHTER
WINDS FOR FRI. THEN WINDS SHUD QUIET DOWN FOR A FEW PERIODS. THEN
FOR THE SECOND HALF OF THE UPCOMING WEEKEND...MUCH WARMER AIR MAY
SLIDE OVER LAKE MICHIGAN SUN. THIS HAS THE POTENTIAL OF CREATING A
RARE LATE JANUARY STABLE MARINE ENVIRONMENT SUN. CONFIDENCE AT THIS
JUNCTURE IS VERY LOW...HOWEVER SOME CONSISTENCY HAS BEEN NOTED
AMONGST FORECAST SOLUTIONS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006 UNTIL 9 PM
TUESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1040 AM CST TUE JAN 17 2012
.DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 16Z...
* TRANSITION FROM RAIN/DRIZZLE TO SNOW OCCURRING AT MDW THIS
HOUR...ALREADY SNOW AT ORD.
* PERIODS OF LIGHT SNOW CONTINUING THROUGH MID AFTERNOON.
* PERIOD OF POTENTIAL ACCUMULATION AND LOWEST VSBY REDUCTION MAY
BE DELAYED UNTIL EARLY AFTERNOON...TAF ADJUSTMENTS POSSIBLE.
* PRIMARILY MVFR CIGS THROUGH AFTERNOON THOUGH SPOTTY IFR MAY
OCCUR YET THIS MORNING AT ORD...IFR TO BECOME MVFR AT MDW SOON
* NORTHWEST WINDS GUSTING TO AROUND 30 KT THROUGH MID AFTERNOON
THEN SLOWLY DIMINISHING.
* POTENTIAL FOR BLOWING SNOW AND SOME VSBY REDUCTION DUE TO IT
ASSUMING SNOW CAN ACCUMULATE.
MDB
//DISCUSSION...UPDATED 16Z...
DETAILS HAVE BECOME MORE CHALLENGING IN TERMS OF VSBY AND SNOW
DETAILS. BANDS OF SNOW CONTINUE TO GENERATE ACROSS EASTERN IOWA
AND MOVE EAST-NORTHEAST. HOWEVER...MUCH OF THE SOUTHERN FLANK OF
THIS DIMINISHES AS IT MOVES CLOSER TO THE AREA. LIGHT SNOW WILL
CONTINUE BUT AM CONCERNED THAT THE POTENTIAL FOR ACCUMULATING SNOW
AND LOWER VSBY IN SNOW/BLSN WILL BE SHIFTED INTO EARLY AFTERNOON
BASED ON LATEST TRENDS. MAY NEED TO MAKE TAF ADJUSTMENTS. CIGS
CONTINUE TO IMPROVE WITH IFR CHANGING TO MVFR AND THEN REMAINING
MVFR THROUGH THE AFTERNOON. NORTHWEST WINDS HAVE COME UP WITH GUSTS
TO AROUND 30 KT. THIS WILL LEAD TO BLOWING SNOW WHERE SNOW
ACCUMULATES AND MAGNITUDE OF ACCUMULATION HAS BECOME LESS CERTAIN
ACROSS THE CHI METRO AIRPORTS...ESPECIALLY MDW/GYY. WILL CONTINUE
TO MONITOR VSBY AND SNOW INTENSITY TRENDS FOR POTENTIAL
ADJUSTMENTS.
MDB
FROM 12Z...
LOW PRESSURE CURRENTLY CENTERED OVER NORTHEAST INDIANA WILL
CONTINUE TO NEAR TORONTO BY THIS EVENING. COLDER AIR WILL SLOWLY
SPREAD ACROSS THE AREA THIS MORNING AS NORTHERLY WINDS ALSO
STEADILY INCREASE AND BECOME QUITE STRONG BY MID/LATE MORNING.
BULK OF THE RAIN HAS SHIFTED EAST OF THE TERMINALS. STILL A FEW
SHOWERS AND DRIZZLE BUT AS THE COLDER AIR SPREADS ACROSS NORTHWEST
IL...PRECIP WILL BEGIN TO TRANSITION TO SNOW. CHANGEOVER SHOULD
OCCUR RATHER QUICKLY WITH SNOW INTO THE CHICAGO AREA TERMINALS BY
15Z OR SO. COULD BE A BRIEF PERIOD OF SLEET OR FREEZING RAIN...
BUT NOT EXPECTING THIS TO BECOMING PREVAILING. THE HEAVIEST OF THE
SNOW IS EXPECTED TO FALL ACROSS FAR NORTHERN IL INTO SOUTHERN
WI...SO THERE REMAINS SOME UNCERTAINTY AS TO JUST HOW LOW CIGS/VIS
WILL DROP AND HOW MUCH SNOW MAY FALL. IN ADDITION...THE SNOW WILL
LIKELY START SOMEWHAT WET AND STEADILY BECOME DRIER OR FLUFFY AS
SNOW/WATER RATIOS INCREASE. WITH THE GRADIENT TIGHTENING ON THE
BACK SIDE OF THE DEPARTING LOW...WINDS GUSTING 25-30 KTS WILL
LIKELY CAUSE BLOWING AND DRIFTING OF THIS DRIER SNOW...WHEREVER IT
FALLS. THE PERIOD OF TIME OF THE HEAVIEST SNOW WILL LIKELY BE
CENTERED AROUND 18Z WITH SNOW ENDING FROM WEST TO EAST DURING THE
EARLY/MID AFTERNOON HRS. GIVEN THE UNCERTAINTY REGARDING
CIGS/VIS...REFINEMENTS...PERHAPS SIGNIFICANT...WITH LATER UPDATES
SHOULD BE EXPECTED.
MVFR CIGS SHOULD LIFT TO VFR BY EARLY EVENING...AND SCATTER OUT BY
EARLY MORNING. NORTHWEST WINDS WILL REMAIN GUSTY DURING THE
EVENING BUT WILL STEADILY DIMINISH LATE IN THE EVENING INTO THE
OVERNIGHT HOURS AS A RIDGE OF HIGH PRESSURE MOVES ACROSS THE AREA
WEDNESDAY MORNING. CMS
//ORD AND MDW CONFIDENCE...UPDATED 16Z...
* HIGH CONFIDENCE IN TRANSITION FROM RAIN TO SNOW AT MDW.
* HIGH CONFIDENCE IN LIGHT SNOW CONTINUING THROUGH MID
AFTERNOON...THOUGH LOW-MEDIUM CONFIDENCE ON ENDING TIME.
* LOW CONFIDENCE IN PERIOD FOR BEST ACCUMULATION POTENTIAL AND
LOWEST VSBY DUE TO SNOW...MAY BE MORE TOWARDS EARLY AFTERNOON.
* HIGH CONFIDENCE IN CEILING TRENDS.
* HIGH CONFIDENCE IN WINDS.
* HIGH CONFIDENCE IN BLOWING SNOW OCCURRING IF ACCUMULATION OCCURS
BUT REDUCED CONFIDENCE IN ACCUMULATION AMOUNTS.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...SLIGHT CHANCE OF SNOW. GUSTY SOUTHWEST WINDS
SHIFTING WESTERLY BY MORNING.
* THURSDAY...SLIGHT CHANCE OF SNOW EARLY. GUSTY NORTHWEST WINDS.
* FRIDAY...SNOW. IFR CIGS. LIFR VIS.
* SATURDAY...VFR.
* SUNDAY...VFR. SLIGHT CHANCE OF RAIN LATE.
* MONDAY...CHANCE OF RAIN. MVFR POSSIBLE. CMS
&&
.MARINE...
254 AM CST
LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL
QUEBEC...WITH A TRAILING AND NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING SOUTHWEST THROUGH NORTHWEST IN/CENTRAL IL. A SERIES OF
WEAK LOW PRESSURE HAVE MOVED ALONG THIS BOUNDARY...HOWEVER GUIDANCE
IS INDICATING THAT TODAY THE BOUNDARY WILL BEGIN TO ADVANCE
EAST/SOUTHEAST AS A PUSH OF MUCH COLDER AIR ARRIVES. EARLY THIS
MORNING OBSERVATIONS HAVE INDICATED WIND GUSTS BETWEEN 10 TO 20 KT
GENERALLY FROM THE NORTH. WITH THE LACK OF A SIGNIFICANT PRESSURE
GRADIENT EARLY THIS MORNING WINDS SHOULD REMAIN LIGHT FOR A BRIEF
PERIOD OF TIME...BEFORE STEADILY RAMPING UP TOWARDS GALES FOR THE
OPEN WATERS AND SOLID SMALL CRAFT CONDITIONS FOR THE NEARSHORE
WATERS.
GUIDANCE HAS CONTINUED TO FOCUS ON A 15-18Z WINDOW FOR WINDS PUSHING
TO 35-40KT ACROSS THE OPEN WATERS OF LAKE MICHIGAN. SREF NEAR SFC
WIND PLUMES HAVE SUGGESTED WINDS AT 18Z WILL BE SUSTAINED ARND 20KT.
THIS COUPLED WITH A HIGH CONFIDENCE OF THE MIXED LAYER BRINGING TO
THE SFC WINDS ARND 850MB OF 40-45KT...SUGGEST HEAVILY THAT GALES
CONFIDENCE IS NEAR 100 PERCENT. THEN BASED ON OPERATIONAL MODELS AND
ENSEMBLES WINDS RAPIDLY DECLINE BY 06Z WED TO ARND 10-20KT
SUSTAINED...AND GUSTS TO 30KT. THIS SHOULD BRING AN END TO THE
GALES...HOWEVER INFREQUENT GALES TO 35KT MAY OCCUR FOR A FEW HOURS
AFT 06Z WED. SMALL CRAFT CONDITIONS WILL PERSIST FOR THE NORTHWEST
INDIANA WATERS THROUGH WED MORNING UNDER A NW FLOW AND ELEVATED
WAVES.
HIGH PRESSURE QUICKLY BUILDS IN FROM THE WEST/SOUTHWEST...AND SHOULD
RELAX WINDS FOR THE REMAINDER OF THE NIGHT INTO EARLY WED. THEN YET
ANOTHER SYSTEM IS PROGGED TO DEVELOP WED NGT AS THE HIGH PRESSURE
DRIFTS EAST. THIS WILL ALLOW A TIGHTENING PRESSURE GRADIENT LATE WED
AS WINDS BACK TO THE SOUTHWEST. CURRENT INDICATIONS ARE THAT LOW END
GALES ARE POSSIBLE EARLY THUR MORNING. THEN A BROAD HIGH PRESSURE
AREA BUILDS IN FROM THE NW AND SHUD PROVIDE A PERIOD OF LIGHTER
WINDS FOR FRI. THEN WINDS SHUD QUIET DOWN FOR A FEW PERIODS. THEN
FOR THE SECOND HALF OF THE UPCOMING WEEKEND...MUCH WARMER AIR MAY
SLIDE OVER LAKE MICHIGAN SUN. THIS HAS THE POTENTIAL OF CREATING A
RARE LATE JANUARY STABLE MARINE ENVIRONMENT SUN. CONFIDENCE AT THIS
JUNCTURE IS VERY LOW...HOWEVER SOME CONSISTENCY HAS BEEN NOTED
AMONGST FORECAST SOLUTIONS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006 UNTIL 9 PM
TUESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
906 AM CST TUE JAN 17 2012
.DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 15Z...
* LIFR CIGS LIFTING THROUGH IFR INTO MVFR BY LATE MORNING.
* LIGHT RAIN/DRIZZLE CHANGING TO SNOW 15-16Z
* HEAVIEST SNOW AND LOWEST VSBY EXPECTED 16-18Z
* SNOW CONTINUING THROUGH MID AFTERNOON WITH POSSIBLE IFR CIGS AND
LIFR VIS.
* STRONG NORTHWEST WINDS GUSTING UP TO 30 KT FROM LATE MORNING
THROUGH LATE AFTERNOON...POSSIBLY CAUSING BLOWING SNOW.
MDB
//DISCUSSION...UPDATED 15Z...
BAND OF LIGHT TO MODERATE SNOW CONTINUES TO MARCH EASTWARD TOWARDS
THE TERMINALS WITH THE HEAVIEST SNOW EXPECTED AT RFD OVER THE NEXT
FEW HOURS. ORD/DPA/MDW/GYY STILL ABOVE FREEZING AND REPORTING
LIGHT RAIN AND DRIZZLE BUT EXPECT THE TRANSITION TO SNOW TO OCCUR
IN THE 15-16Z HOUR AT THE IL TERMINALS AND A BIT LATER AT GYY.
BAND OF SNOW LOOKS TO CROSS ORD/MDW/DPA AND MAY STAY JUST NORTH OF
GYY. EXPECT VSBY IN SNOW IN THE 1-2SM RANGE WITH 3/4 POSSIBLE AT
TIMES...WITH RFD LIKELY SEEING THE LONGEST DURATION OF LOWEST VSBY.
IFR CIGS WILL IMPROVE TO LOW END MVFR AS COLDER AIR WORKS IN BUT
IFR AND LIFR WILL CONTINUE AT THE CHICAGO METRO AND GARY TERMINALS
FOR A FEW HOURS YET. WINDS STILL ON TRACK TO BECOME MORE
NORTHWESTERLY AND INCREASE IN SPEED INTO MIDDAY.
FROM 12Z...
LOW PRESSURE CURRENTLY CENTERED OVER NORTHEAST INDIANA WILL
CONTINUE TO NEAR TORONTO BY THIS EVENING. COLDER AIR WILL SLOWLY
SPREAD ACROSS THE AREA THIS MORNING AS NORTHERLY WINDS ALSO
STEADILY INCREASE AND BECOME QUITE STRONG BY MID/LATE MORNING.
BULK OF THE RAIN HAS SHIFTED EAST OF THE TERMINALS. STILL A FEW
SHOWERS AND DRIZZLE BUT AS THE COLDER AIR SPREADS ACROSS NORTHWEST
IL...PRECIP WILL BEGIN TO TRANSITION TO SNOW. CHANGEOVER SHOULD
OCCUR RATHER QUICKLY WITH SNOW INTO THE CHICAGO AREA TERMINALS BY
15Z OR SO. COULD BE A BRIEF PERIOD OF SLEET OR FREEZING RAIN...
BUT NOT EXPECTING THIS TO BECOMING PREVAILING. THE HEAVIEST OF THE
SNOW IS EXPECTED TO FALL ACROSS FAR NORTHERN IL INTO SOUTHERN
WI...SO THERE REMAINS SOME UNCERTAINTY AS TO JUST HOW LOW CIGS/VIS
WILL DROP AND HOW MUCH SNOW MAY FALL. IN ADDITION...THE SNOW WILL
LIKELY START SOMEWHAT WET AND STEADILY BECOME DRIER OR FLUFFY AS
SNOW/WATER RATIOS INCREASE. WITH THE GRADIENT TIGHTENING ON THE
BACK SIDE OF THE DEPARTING LOW...WINDS GUSTING 25-30 KTS WILL
LIKELY CAUSE BLOWING AND DRIFTING OF THIS DRIER SNOW...WHEREVER IT
FALLS. THE PERIOD OF TIME OF THE HEAVIEST SNOW WILL LIKELY BE
CENTERED AROUND 18Z WITH SNOW ENDING FROM WEST TO EAST DURING THE
EARLY/MID AFTERNOON HRS. GIVEN THE UNCERTAINTY REGARDING
CIGS/VIS...REFINEMENTS...PERHAPS SIGNIFICANT...WITH LATER UPDATES
SHOULD BE EXPECTED.
MVFR CIGS SHOULD LIFT TO VFR BY EARLY EVENING...AND SCATTER OUT BY
EARLY MORNING. NORTHWEST WINDS WILL REMAIN GUSTY DURING THE
EVENING BUT WILL STEADILY DIMINISH LATE IN THE EVENING INTO THE
OVERNIGHT HOURS AS A RIDGE OF HIGH PRESSURE MOVES ACROSS THE AREA
WEDNESDAY MORNING. CMS
//ORD AND MDW CONFIDENCE...UPDATED 15Z...
* MEDIUM CONFIDENCE REGARDING CIG SPECIFICS BUT HIGH CONFIDENCE IN
TREND.
* HIGH CONFIDENCE LIGHT RAIN/DRIZZLE WILL TRANSITION TO SNOW BY
ABOUT 16Z.
* MEDIUM-HIGH CONFIDENCE IN HEAVIEST SNOW 16-18Z...POSSIBLY A BIT
LONGER.
* HIGH CONFIDENCE IN LESS INTENSE CONTINUING INTO MID AFTERNOON
BUT LOW CONFIDENCE IN END TIME.
* MEDIUM-HIGH CONFIDENCE REGARDING WIND SPEEDS/GUSTS/DURATION.
MDB
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...SLIGHT CHANCE OF SNOW. GUSTY SOUTHWEST WINDS
SHIFTING WESTERLY BY MORNING.
* THURSDAY...SLIGHT CHANCE OF SNOW EARLY. GUSTY NORTHWEST WINDS.
* FRIDAY...SNOW. IFR CIGS. LIFR VIS.
* SATURDAY...VFR.
* SUNDAY...VFR. SLIGHT CHANCE OF RAIN LATE.
* MONDAY...CHANCE OF RAIN. MVFR POSSIBLE. CMS
&&
.MARINE...
254 AM CST
LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL
QUEBEC...WITH A TRAILING AND NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING SOUTHWEST THROUGH NORTHWEST IN/CENTRAL IL. A SERIES OF
WEAK LOW PRESSURE HAVE MOVED ALONG THIS BOUNDARY...HOWEVER GUIDANCE
IS INDICATING THAT TODAY THE BOUNDARY WILL BEGIN TO ADVANCE
EAST/SOUTHEAST AS A PUSH OF MUCH COLDER AIR ARRIVES. EARLY THIS
MORNING OBSERVATIONS HAVE INDICATED WIND GUSTS BETWEEN 10 TO 20 KT
GENERALLY FROM THE NORTH. WITH THE LACK OF A SIGNIFICANT PRESSURE
GRADIENT EARLY THIS MORNING WINDS SHOULD REMAIN LIGHT FOR A BRIEF
PERIOD OF TIME...BEFORE STEADILY RAMPING UP TOWARDS GALES FOR THE
OPEN WATERS AND SOLID SMALL CRAFT CONDITIONS FOR THE NEARSHORE
WATERS.
GUIDANCE HAS CONTINUED TO FOCUS ON A 15-18Z WINDOW FOR WINDS PUSHING
TO 35-40KT ACROSS THE OPEN WATERS OF LAKE MICHIGAN. SREF NEAR SFC
WIND PLUMES HAVE SUGGESTED WINDS AT 18Z WILL BE SUSTAINED ARND 20KT.
THIS COUPLED WITH A HIGH CONFIDENCE OF THE MIXED LAYER BRINGING TO
THE SFC WINDS ARND 850MB OF 40-45KT...SUGGEST HEAVILY THAT GALES
CONFIDENCE IS NEAR 100 PERCENT. THEN BASED ON OPERATIONAL MODELS AND
ENSEMBLES WINDS RAPIDLY DECLINE BY 06Z WED TO ARND 10-20KT
SUSTAINED...AND GUSTS TO 30KT. THIS SHOULD BRING AN END TO THE
GALES...HOWEVER INFREQUENT GALES TO 35KT MAY OCCUR FOR A FEW HOURS
AFT 06Z WED. SMALL CRAFT CONDITIONS WILL PERSIST FOR THE NORTHWEST
INDIANA WATERS THROUGH WED MORNING UNDER A NW FLOW AND ELEVATED
WAVES.
HIGH PRESSURE QUICKLY BUILDS IN FROM THE WEST/SOUTHWEST...AND SHOULD
RELAX WINDS FOR THE REMAINDER OF THE NIGHT INTO EARLY WED. THEN YET
ANOTHER SYSTEM IS PROGGED TO DEVELOP WED NGT AS THE HIGH PRESSURE
DRIFTS EAST. THIS WILL ALLOW A TIGHTENING PRESSURE GRADIENT LATE WED
AS WINDS BACK TO THE SOUTHWEST. CURRENT INDICATIONS ARE THAT LOW END
GALES ARE POSSIBLE EARLY THUR MORNING. THEN A BROAD HIGH PRESSURE
AREA BUILDS IN FROM THE NW AND SHUD PROVIDE A PERIOD OF LIGHTER
WINDS FOR FRI. THEN WINDS SHUD QUIET DOWN FOR A FEW PERIODS. THEN
FOR THE SECOND HALF OF THE UPCOMING WEEKEND...MUCH WARMER AIR MAY
SLIDE OVER LAKE MICHIGAN SUN. THIS HAS THE POTENTIAL OF CREATING A
RARE LATE JANUARY STABLE MARINE ENVIRONMENT SUN. CONFIDENCE AT THIS
JUNCTURE IS VERY LOW...HOWEVER SOME CONSISTENCY HAS BEEN NOTED
AMONGST FORECAST SOLUTIONS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006 UNTIL 9 PM
TUESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 10 PM TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
GALE WARNING...INDIANA NEARSHORE WATERS UNTIL NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
601 AM CST TUE JAN 17 2012
.DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 12Z...
* LIFR CIGS LIFTING THROUGH IFR INTO MVFR BY LATE MORNING.
* LIGHT RAIN/DRIZZLE CHANGING TO SNOW BY MID/LATE MORNING.
* SNOW CONTINUING THROUGH MID AFTERNOON WITH POSSIBLE IFR CIGS AND
LIFR VIS.
* STRONG NORTHWEST WINDS GUSTING UP TO 30 KT FROM MID/LATE MORNING
THROUGH LATE AFTERNOON...POSSIBLY CAUSING BLOWING SNOW. CMS
//DISCUSSION...UPDATED 12Z...
LOW PRESSURE CURRENTLY CENTERED OVER NORTHEAST INDIANA WILL
CONTINUE TO NEAR TORONTO BY THIS EVENING. COLDER AIR WILL SLOWLY
SPREAD ACROSS THE AREA THIS MORNING AS NORTHERLY WINDS ALSO
STEADILY INCREASE AND BECOME QUITE STRONG BY MID/LATE MORNING.
BULK OF THE RAIN HAS SHIFTED EAST OF THE TERMINALS. STILL A FEW
SHOWERS AND DRIZZLE BUT AS THE COLDER AIR SPREADS ACROSS NORTHWEST
IL...PRECIP WILL BEGIN TO TRANSITION TO SNOW. CHANGEOVER SHOULD
OCCUR RATHER QUICKLY WITH SNOW INTO THE CHICAGO AREA TERMINALS BY
15Z OR SO. COULD BE A BRIEF PERIOD OF SLEET OR FREEZING RAIN...
BUT NOT EXPECTING THIS TO BECOMING PREVAILING. THE HEAVIEST OF THE
SNOW IS EXPECTED TO FALL ACROSS FAR NORTHERN IL INTO SOUTHERN
WI...SO THERE REMAINS SOME UNCERTAINTY AS TO JUST HOW LOW CIGS/VIS
WILL DROP AND HOW MUCH SNOW MAY FALL. IN ADDITION...THE SNOW WILL
LIKELY START SOMEWHAT WET AND STEADILY BECOME DRIER OR FLUFFY AS
SNOW/WATER RATIOS INCREASE. WITH THE GRADIENT TIGHTENING ON THE
BACK SIDE OF THE DEPARTING LOW...WINDS GUSTING 25-30 KTS WILL
LIKELY CAUSE BLOWING AND DRIFTING OF THIS DRIER SNOW...WHEREVER IT
FALLS. THE PERIOD OF TIME OF THE HEAVIEST SNOW WILL LIKELY BE
CENTERED AROUND 18Z WITH SNOW ENDING FROM WEST TO EAST DURING THE
EARLY/MID AFTERNOON HRS. GIVEN THE UNCERTAINTY REGARDING
CIGS/VIS...REFINEMENTS...PERHAPS SIGNIFICANT...WITH LATER UPDATES
SHOULD BE EXPECTED.
MVFR CIGS SHOULD LIFT TO VFR BY EARLY EVENING...AND SCATTER OUT BY
EARLY MORNING. NORTHWEST WINDS WILL REMAIN GUSTY DURING THE
EVENING BUT WILL STEADILY DIMINISH LATE IN THE EVENING INTO THE
OVERNIGHT HOURS AS A RIDGE OF HIGH PRESSURE MOVES ACROSS THE AREA
WEDNESDAY MORNING. CMS
//ORD AND MDW CONFIDENCE...UPDATED 12Z...
* MEDIUM CONFIDENCE REGARDING CIG TRENDS.
* HIGH CONFIDENCE LIGHT RAIN/DRIZZLE WILL TRANSITION TO SNOW BY
MID/LATE MORNING.
* HIGH CONFIDENCE REGARDING SNOW LATER THIS MORNING INTO THIS
AFTERNOON...LOW CONFIDENCE REGARDING SPECIFICS ON TIMING...
VIS/CIGS AND AMOUNTS.
* MEDIUM CONFIDENCE REGARDING WIND SPEEDS/GUSTS/DURATION. CMS
//OUTLOOK FOR ORD/MDW FOR 00Z THURSDAY-12Z TUESDAY...UPDATED 12Z...
* WEDNESDAY NIGHT...SLIGHT CHANCE OF SNOW. GUSTY SOUTHWEST WINDS
SHIFTING WESTERLY BY MORNING.
* THURSDAY...SLIGHT CHANCE OF SNOW EARLY. GUSTY NORTHWEST WINDS.
* FRIDAY...SNOW. IFR CIGS. LIFR VIS.
* SATURDAY...VFR.
* SUNDAY...VFR. SLIGHT CHANCE OF RAIN LATE.
* MONDAY...CHANCE OF RAIN. MVFR POSSIBLE. CMS
&&
.MARINE...
254 AM CST
LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL
QUEBEC...WITH A TRAILING AND NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING SOUTHWEST THROUGH NORTHWEST IN/CENTRAL IL. A SERIES OF
WEAK LOW PRESSURE HAVE MOVED ALONG THIS BOUNDARY...HOWEVER GUIDANCE
IS INDICATING THAT TODAY THE BOUNDARY WILL BEGIN TO ADVANCE
EAST/SOUTHEAST AS A PUSH OF MUCH COLDER AIR ARRIVES. EARLY THIS
MORNING OBSERVATIONS HAVE INDICATED WIND GUSTS BETWEEN 10 TO 20 KT
GENERALLY FROM THE NORTH. WITH THE LACK OF A SIGNIFICANT PRESSURE
GRADIENT EARLY THIS MORNING WINDS SHOULD REMAIN LIGHT FOR A BRIEF
PERIOD OF TIME...BEFORE STEADILY RAMPING UP TOWARDS GALES FOR THE
OPEN WATERS AND SOLID SMALL CRAFT CONDITIONS FOR THE NEARSHORE
WATERS.
GUIDANCE HAS CONTINUED TO FOCUS ON A 15-18Z WINDOW FOR WINDS PUSHING
TO 35-40KT ACROSS THE OPEN WATERS OF LAKE MICHIGAN. SREF NEAR SFC
WIND PLUMES HAVE SUGGESTED WINDS AT 18Z WILL BE SUSTAINED ARND 20KT.
THIS COUPLED WITH A HIGH CONFIDENCE OF THE MIXED LAYER BRINGING TO
THE SFC WINDS ARND 850MB OF 40-45KT...SUGGEST HEAVILY THAT GALES
CONFIDENCE IS NEAR 100 PERCENT. THEN BASED ON OPERATIONAL MODELS AND
ENSEMBLES WINDS RAPIDLY DECLINE BY 06Z WED TO ARND 10-20KT
SUSTAINED...AND GUSTS TO 30KT. THIS SHOULD BRING AN END TO THE
GALES...HOWEVER INFREQUENT GALES TO 35KT MAY OCCUR FOR A FEW HOURS
AFT 06Z WED. SMALL CRAFT CONDITIONS WILL PERSIST FOR THE NORTHWEST
INDIANA WATERS THROUGH WED MORNING UNDER A NW FLOW AND ELEVATED
WAVES.
HIGH PRESSURE QUICKLY BUILDS IN FROM THE WEST/SOUTHWEST...AND SHOULD
RELAX WINDS FOR THE REMAINDER OF THE NIGHT INTO EARLY WED. THEN YET
ANOTHER SYSTEM IS PROGGED TO DEVELOP WED NGT AS THE HIGH PRESSURE
DRIFTS EAST. THIS WILL ALLOW A TIGHTENING PRESSURE GRADIENT LATE WED
AS WINDS BACK TO THE SOUTHWEST. CURRENT INDICATIONS ARE THAT LOW END
GALES ARE POSSIBLE EARLY THUR MORNING. THEN A BROAD HIGH PRESSURE
AREA BUILDS IN FROM THE NW AND SHUD PROVIDE A PERIOD OF LIGHTER
WINDS FOR FRI. THEN WINDS SHUD QUIET DOWN FOR A FEW PERIODS. THEN
FOR THE SECOND HALF OF THE UPCOMING WEEKEND...MUCH WARMER AIR MAY
SLIDE OVER LAKE MICHIGAN SUN. THIS HAS THE POTENTIAL OF CREATING A
RARE LATE JANUARY STABLE MARINE ENVIRONMENT SUN. CONFIDENCE AT THIS
JUNCTURE IS VERY LOW...HOWEVER SOME CONSISTENCY HAS BEEN NOTED
AMONGST FORECAST SOLUTIONS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...WINTER WEATHER ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006 UNTIL 9 PM
TUESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM TUESDAY TO 10 PM
TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...9 AM TUESDAY TO
NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
408 AM CST TUE JAN 17 2012
.DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 10Z...
* LIFR CIGS LIFTING TO IFR BY MID MORNING AND MVFR BY LATE
MORNING.
* LIGHT RAIN/DRIZZLE CHANGING TO SNOW MID/LATE MORNING WITH SNOW
CONTINUING INTO THIS AFTERNOON.
* NORTHWEST WINDS GUSTING TO NEAR 30 KTS FROM LATE MORNING THROUGH
LATE AFTERNOON. CMS
//DISCUSSION...UPDATED 06Z...
THE SURFACE FRONT CONTINUES DRAPED FROM WESTERN IL THROUGH CHICAGO
INTO LOWER MI. LOW PRESSURE IS EVOLVING NORTHEAST ALONG THIS
FEATURE THROUGH THE EARLY MORNING. EARLIER SHOWERS HAVE
DECREASED IN COVERAGE...HOWEVER A RE-INCREASE IN SHOWER COVERAGE
IS EXPECTED BY 09Z. SOME OF THE SHOWERS MAY PUT DOWN BRIEF
MODERATE TO HEAVY RAIN. SOME THUNDER IS POSSIBLE ACROSS THE
SOUTHERN GATES AND HAS ALREADY BEEN OBSERVED JUST NORTH OF KLAF.
SURFACE TEMPERATURES WILL REMAIN ABOVE FREEZING THROUGH 12Z WITH
HIGH CONFIDENCE...SO DO NOT EXPECT ANY FREEZING PRECIPITATION. AS
THE LOW MOVES TO THE IMMEDIATE EAST OF THE AREA BY MID
MORNING...THE ATMOSPHERIC TEMPERATURES WILL COOL SIGNIFICANTLY
FAVORING PRECIPITATION TYPE TO BE SNOW. A BRIEF MIX MAY OCCUR AT
THE LEADING EDGE OF THIS TRANSITION. WITH THE ARRIVAL OF THE SNOW
WILL ALSO COME THE ONSET OF STRONG NORTHWEST WINDS. GUSTS TO NEAR
30 KTS ARE HIGHLY LIKELY...AND THE COMBINATION OF THAT AND FALLING
SNOW WILL LIKELY LEAD TO REDUCED VISIBILITY TO 1SM OR EVEN LOWER
FOR A WHILE NEAR MIDDAY. WHILE THE CEILINGS WILL IMPROVE SLOWLY
DURING THE AFTERNOON...THE SNOW SHOULD LAST UNTIL 21Z-23Z OR SO
BEFORE ENDING. SCATTERING IS LIKELY DURING THE EVENING. MTF
//ORD AND MDW CONFIDENCE...UPDATED 10Z...
* HIGH CONFIDENCE REGARDING CIGS THROUGH MID MORNING...LOW
CONFIDENCE FROM LATE MORNING INTO THIS AFTERNOON.
* HIGH CONFIDENCE LIGHT RAIN/DRIZZLE WILL CONTINUE THROUGH MID
MORNING...THEN CHANGE TO SNOW.
* HIGH CONFIDENCE REGARDING SNOW LATER THIS MORNING INTO THIS
AFTERNOON...LOW CONFIDENCE REGARDING SPECIFICS ON TIMING...
VIS/CIGS AND AMOUNTS.
* MEDIUM CONFIDENCE REGARDING WIND SPEEDS/GUSTS/DURATION. CMS
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...VFR. MVFR AND GUSTY WEST NORTHWEST WINDS DEVELOPING
DURING THE NIGHT.
THURSDAY...MVFR POSSIBLE. GUSTY NORTHWEST WINDS.
FRIDAY...MVFR...WITH IFR POSSIBLE. CHANCE OF SNOW.
SATURDAY...SLIGHT CHANCE OF RAIN/SNOW.
SUNDAY...SLIGHT CHANCE OF RAIN OR SNOW DURING THE NIGHT.
MTF
&&
.MARINE...
254 AM CST
LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL
QUEBEC...WITH A TRAILING AND NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING SOUTHWEST THROUGH NORTHWEST IN/CENTRAL IL. A SERIES OF
WEAK LOW PRESSURE HAVE MOVED ALONG THIS BOUNDARY...HOWEVER GUIDANCE
IS INDICATING THAT TODAY THE BOUNDARY WILL BEGIN TO ADVANCE
EAST/SOUTHEAST AS A PUSH OF MUCH COLDER AIR ARRIVES. EARLY THIS
MORNING OBSERVATIONS HAVE INDICATED WIND GUSTS BETWEEN 10 TO 20 KT
GENERALLY FROM THE NORTH. WITH THE LACK OF A SIGNIFICANT PRESSURE
GRADIENT EARLY THIS MORNING WINDS SHOULD REMAIN LIGHT FOR A BRIEF
PERIOD OF TIME...BEFORE STEADILY RAMPING UP TOWARDS GALES FOR THE
OPEN WATERS AND SOLID SMALL CRAFT CONDITIONS FOR THE NEARSHORE
WATERS.
GUIDANCE HAS CONTINUED TO FOCUS ON A 15-18Z WINDOW FOR WINDS PUSHING
TO 35-40KT ACROSS THE OPEN WATERS OF LAKE MICHIGAN. SREF NEAR SFC
WIND PLUMES HAVE SUGGESTED WINDS AT 18Z WILL BE SUSTAINED ARND 20KT.
THIS COUPLED WITH A HIGH CONFIDENCE OF THE MIXED LAYER BRINGING TO
THE SFC WINDS ARND 850MB OF 40-45KT...SUGGEST HEAVILY THAT GALES
CONFIDENCE IS NEAR 100 PERCENT. THEN BASED ON OPERATIONAL MODELS AND
ENSEMBLES WINDS RAPIDLY DECLINE BY 06Z WED TO ARND 10-20KT
SUSTAINED...AND GUSTS TO 30KT. THIS SHOULD BRING AN END TO THE
GALES...HOWEVER INFREQUENT GALES TO 35KT MAY OCCUR FOR A FEW HOURS
AFT 06Z WED. SMALL CRAFT CONDITIONS WILL PERSIST FOR THE NORTHWEST
INDIANA WATERS THROUGH WED MORNING UNDER A NW FLOW AND ELEVATED
WAVES.
HIGH PRESSURE QUICKLY BUILDS IN FROM THE WEST/SOUTHWEST...AND SHOULD
RELAX WINDS FOR THE REMAINDER OF THE NIGHT INTO EARLY WED. THEN YET
ANOTHER SYSTEM IS PROGGED TO DEVELOP WED NGT AS THE HIGH PRESSURE
DRIFTS EAST. THIS WILL ALLOW A TIGHTENING PRESSURE GRADIENT LATE WED
AS WINDS BACK TO THE SOUTHWEST. CURRENT INDICATIONS ARE THAT LOW END
GALES ARE POSSIBLE EARLY THUR MORNING. THEN A BROAD HIGH PRESSURE
AREA BUILDS IN FROM THE NW AND SHUD PROVIDE A PERIOD OF LIGHTER
WINDS FOR FRI. THEN WINDS SHUD QUIET DOWN FOR A FEW PERIODS. THEN
FOR THE SECOND HALF OF THE UPCOMING WEEKEND...MUCH WARMER AIR MAY
SLIDE OVER LAKE MICHIGAN SUN. THIS HAS THE POTENTIAL OF CREATING A
RARE LATE JANUARY STABLE MARINE ENVIRONMENT SUN. CONFIDENCE AT THIS
JUNCTURE IS VERY LOW...HOWEVER SOME CONSISTENCY HAS BEEN NOTED
AMONGST FORECAST SOLUTIONS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM TUESDAY TO 10 PM
TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...9 AM TUESDAY TO
NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
359 AM CST TUE JAN 17 2012
.DISCUSSION...
354 AM CST
MAIN CONCERNS REVOLVE AROUND VARYING PRECIP TYPE EARLY THIS
MORNING WITH RAIN/THUNDERSTORMS CURRENTLY ONGOING ACROSS THE
SOUTHERN HALF OF THE CWA AND RAIN FOR THE MIDDLE HALF...BUT WITH A
TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST THROUGH THIS
MORNING. HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE TOP TIER OF
COUNTIES IN ILLINOIS WITH SNOWFALL TOTALS IN NORTHERN ILLINOIS
PUSHING 3-4 INCHES...AND ISSUES WITH REDUCED VISIBILITY DUE TO
BLOWING SNOW.
VERY COMPLEX SITUATION ONGOING ACROSS THE CWA THIS MORNING AS A
WIDE RANGE OF FORECAST CONCERNS REMAIN...WITH CURRENTLY KEEPING AN
EYE ON THUNDERSTORM POTENTIAL FOR THE FAR SOUTHERN AREA OF THE
CWA. LATEST RADAR IMAGERY IS SHOWING A LARGE AREA OF SHOWERS AND
THUNDERSTORMS CURRENTLY MOVING EAST/NORTHEAST FROM CENTRAL
ILLINOIS NORTHEAST TO NORTHERN INDIANA. THESE THUNDERSTORMS ARE
DEVELOPING IN THE WARM SECTOR OF CURRENT SURFACE LOW SITUATED OVER
EAST CENTRAL ILLINOIS. IN THIS WARM SECTOR...TEMPERATURES HAVE
RISEN TO THE LOW TO MID 50S WITH SURFACE DEWPOINTS ALSO RISING TO
THE LOWER 50S. THIS IS PROVIDING FOR A FAIRLY UNSTABLE ENVIRONMENT
FOR THIS TIME OF THE YEAR WITH MID LEVEL LAPSE RATES ON THE
INCREASE AS WELL AS LATEST RUC ANALYSIS INDICATING THAT AN
INSTABILITY AXIS WITH AROUND 500J/KG OF MUCAPE IS SITUATED FROM
SOUTHERN ILLINOIS TO NORTHERN INDIANA. ALL OF THESE ELEMENTS
COINCIDING WITH STRONG LOW AND MID LEVEL CONVERGENCE...A 50KT
LLJ...AND LARGE SCALE FORCING FOR ASCENT OWING TO SEVERAL MID
LEVEL FEATURES PROPAGATING TO THE NORTHEAST OUT AHEAD OF A
LONGWAVE TROUGH TO THE WEST...IS PROVIDING A DECENT SETUP FOR
THUNDERSTORM DEVELOPMENT ACROSS PART OF THE AREA. STRONG MID LEVEL
FLOW IS AIDING IN DECENT BULK SHEAR VALUES RIGHT ACROSS THE
SOUTHERN CWA THIS MORNING. A FEW STORMS HAVE BEEN ABLE TO REALIZE
ALL OF THIS WITH SOME MORE ORGANIZED STORMS RIDING ALONG JUST TO
THE SOUTH OF THE CWA. ALTHOUGH LATEST TRENDS AND SURFACE
OBSERVATIONS LEAD ME TO BELIEVE THAT OUR CWA HAS SEEN THE WINDOW
OF OPPORTUNITY FOR GOOD THUNDERSTORM DEVELOPMENT...WITH BETTER
CHANCES FOR MORE ORGANIZED CONVECTION TO REMAIN JUST TO THE
SOUTH/SOUTHEAST OF THE CWA.
WILL THEN SHIFT GEARS BACK TOWARDS MORE WINTER TIME PRECIP
EXPECTED OVER THIS MORNING. AS MID/UPPER LEVEL TROUGH SHIFTS EAST
ACROSS THE CENTRAL CONUS AND CURRENT SURFACE LOW SHIFTS
EAST...LATEST RADAR IMAGERY IS SHOWING AN AREA OF SNOWFALL
CONTINUING TO DEVELOP AND SHIFT EAST ACROSS CENTRAL IOWA EARLY
THIS MORNING. EXPECT THIS PRECIP TO SHIFT EAST ACROSS THE NORTHERN
HALF OF THE CWA THIS MORNING WITH AREAS ACROSS NORTHWEST/NORTHERN
ILLINOIS OBSERVING SNOW...AND AREAS FROM LA SALLE NORTHEAST TO
CHICAGO INITIALLY OBSERVING RAIN AND THEN A RAIN/SNOW MIX THROUGH
MID MORNING. HAVE REMOVED ANY MENTION OF FREEZING RAIN FOR THIS
MORNING...NOT EXPECTING THIS TO BE A THREAT ANYMORE ANYWHERE
ACROSS THE CWA AS SURFACE TEMPERATURES REMAIN WELL ABOVE FREEZING.
WITH COLDER AIR AND DEEPER MOISTURE QUICKLY SHIFTING EAST THIS
MORNING...A MORE LIKELY SCENARIO WILL BE A QUICK TRANSITION OVER
TO SNOW THROUGH MID MORNING AS LARGE SCALE FORCING/MID LEVEL
TROUGH SHIFT EAST WITH THIS DEFORMATION ZONE ALSO MOVING INTO THE
CWA. MODEL GUIDANCE IN FAIR AGREEMENT WITH LATEST TRENDS TODAY
WITH BEST FORCING ARRIVING LATE THIS MORNING INTO THE NOON TIME
FRAME AS LOW AND MID LEVEL FRONTOGENESIS HELPS TO MAXIMIZE LIFT.
THIS ENHANCED LIFT WILL ALSO COINCIDE WITH STEEPENING MID LEVEL
LAPSE RATES THROUGH THIS TIME...WITH LIGHT TO MODERATE SNOW
FALLING AT TIMES. CURRENT TRENDS AND GUIDANCE WOULD SUGGEST THAT
BEST FORCING AND HIGHER SNOWFALL AMOUNTS WILL OCCUR MORE TOWARDS
THE NORTHERN PORTIONS OF THE CWA WHERE AROUND 3 INCHES OF SNOW IS
CURRENTLY FORECAST...WITH LOCALLY HIGHER AMOUNTS POSSIBLE IF
BANDED SNOWFALL COULD GET GOING. THIS SNOW WILL INITIALLY BE A WET
SNOW ACROSS THE CWA...BUT WITH COLDER AIR QUICKLY SWEEPING
THROUGH...EXPECT SNOW TO BECOME DRIER INTO THE EARLY AFTERNOON.
THIS DRIER SNOW WILL BECOME PROBLEMATIC AS LOW LEVEL MIXING WILL
HELP WIND GUSTS OF 30-40MPH TO DEVELOP...AND BLOWING SNOW BECOMING
AN ISSUE ACROSS MUCH OF NORTHERN ILLINOIS.
AREAS FROM LA SALLE TO CHICAGO CAN EXPECT SNOW TO BECOME MORE
PREVAILING BY THE MID MORNING TIME FRAME...WITH 1 TO 3 INCHES
EXPECTED IN THIS GENERAL AREA TODAY. AREAS IN THE SOUTHERN HALF OF
THE CWA CAN EXPECT A CHANGE OVER TO ALL SNOW BY MID DAY WHERE 1 TO
2 INCHES WILL BE POSSIBLE. EXPECT SNOW TO CONTINUE INTO THE
AFTERNOON...BUT WITH GUIDANCE INDICATING THAT MUCH DRIER AIR WILL
BEGIN TO FILTER IN FROM THE SOUTHWEST. THIS COULD POSSIBLY BRING A
PERIOD OF DRIER CONDITIONS FOR THE FAR SOUTHERN TIER OF COUNTIES
IN THE CWA INTO THE AFTERNOON BEFORE WRAP MOISTURE SHIFTS EAST. IN
ALL...SNOW WILL BE DIMINISHING LATE THIS AFTERNOON INTO THE EARLY
EVENING. HIGH PRESSURE WILL THEN SHIFT OVER THE REGION TONIGHT
WITH SKIES CLEARING AND TEMPERATURES FALLING...AS MUCH COLDER
CONDITIONS EXPECTED TONIGHT WITH FORECAST LOWS IN THE SINGLE
DIGITS POSSIBLE.
RODRIGUEZ
EXTENDED...FRIDAY THROUGH MONDAY...
218 AM CST...
THE MAIN CONCERNS DURING THE EXTENDED PERIOD WILL INITIALLY BE WITH
SNOWFALL CHANCES ON FRIDAY...AND THEN THE POTENTIAL FOR A
SIGNIFICANT WARM UP BY EARLY NEXT WEEK.
MID AND UPPER LEVEL ENERGY IS EXPECTED TO UNDERCUT THE BLOCKING
RIDGE OF HIGH PRESSURE ACROSS THE BERING SEA DURING THE SHORT TERM
PERIOD. THIS WILL ALLOW A SIGNIFICANT SHORT WAVE TO DIG EAST
SOUTHEASTWARD THROUGH THE FAST WEST NORTHWEST FLOW ACROSS THE CONUS
LATER THIS WEEK. THERE ARE SOME SLIGHT TIMING DIFFERENCES AMONGST
THE VARIOUS MODEL GUIDANCE. HOWEVER...THE OVERALL CONSENSUS IS TO
BRING THE PRECIPITATION ACROSS NORTHERN ILLINOIS AND NORTHWESTERN
INDIANA ON FRIDAY AND FRIDAY EVENING.
IT APPEARS THAT ALTHOUGH THIS WILL BE A RATHER FAST MOVING
SYSTEM...THERE WILL BE A SHOT OF GETTING A FAIR AMOUNT OF SNOW
ACROSS A PORTION OF THE GREAT LAKES REGION. THERE WILL LIKELY BE A
STRONG BAROCLINIC ZONE ACROSS THE AREA...SETTING THE STAGE FOR A
POSSIBLE STRONGLY FORCED FRONTOGENETIC BAND OF SNOW. SNOW RATIOS WOULD
ALSO LIKELY BE FAIRLY HIGH...AROUND 20 TO 1 OR POSSIBLY HIGHER IN
SOME AREAS AS TEMPERATURES THROUGH THE COLUMN LOOK COLD. BUFFER
SOUNDINGS FROM THE GFS SUGGEST AN INCREDIBLY DEEP SATURATED DENDRITIC
GROWTH LAYER...FROM NEAR THE SURFACE UP TO AROUND 550MB. THIS COULD
SET UP EFFICIENT SNOWFALL PRODUCTION.
DEPENDING ON IF AND HOW MUCH SNOW OCCURS ON FRIDAY WILL DEPEND HOW
QUICKLY THINGS WARM UP OVER THE WEEKEND. HOWEVER...IT DOES APPEAR
THAT A SIGNIFICANT WARM UP WILL TAKE PLACE BY LATE WEEKEND INTO
EARLY NEXT WEEK. THIS WILL OCCUR AS THE LARGE SCALE PATTERN ACROSS
NORTHERN AMERICA SHIFTS. A SIGNIFICANT CHUNK OF THE POLAR VORTEX
ACROSS NORTHERN CANADA WILL BE FORCED SOUTHWESTWARD ACROSS ALASKA
AND THE NORTHEAST PACIFIC. THE RESULT OF THIS WILL BE RISING HEIGHTS
ACROSS MUCH OF THE CENTRAL AND EASTERN CONUS. THIS WILL LIKELY
RESULT IN A RETURN TO SOME UNSEASONABLE MILD WEATHER ACROSS THE
REGION INTO NEXT WEEK.
KJB
&&
.AVIATION...
//ORD AND MDW CONCERNS...UPDATED 08Z...
* IFR/LIFR CIGS EARLY THIS MORNING LIFTING TO MVFR CIGS BY
MID/LATE MORNING.
* A PERIOD OF LIGHT RAIN BEFORE DAYBREAK...THEN A PERIOD OF SNOW
FROM MID/LATE MORNING INTO MID AFTERNOON.
* NORTHWEST WINDS GUSTING TO NEAR 30 KTS FROM LATE MORNING
THROUGH LATE AFTERNOON. CMS
//DISCUSSION...UPDATED 06Z...
THE SURFACE FRONT CONTINUES DRAPED FROM WESTERN IL THROUGH CHICAGO
INTO LOWER MI. LOW PRESSURE IS EVOLVING NORTHEAST ALONG THIS
FEATURE THROUGH THE EARLY MORNING. EARLIER SHOWERS HAVE
DECREASED IN COVERAGE...HOWEVER A RE-INCREASE IN SHOWER COVERAGE
IS EXPECTED BY 09Z. SOME OF THE SHOWERS MAY PUT DOWN BRIEF
MODERATE TO HEAVY RAIN. SOME THUNDER IS POSSIBLE ACROSS THE
SOUTHERN GATES AND HAS ALREADY BEEN OBSERVED JUST NORTH OF KLAF.
SURFACE TEMPERATURES WILL REMAIN ABOVE FREEZING THROUGH 12Z WITH
HIGH CONFIDENCE...SO DO NOT EXPECT ANY FREEZING PRECIPITATION. AS
THE LOW MOVES TO THE IMMEDIATE EAST OF THE AREA BY MID
MORNING...THE ATMOSPHERIC TEMPERATURES WILL COOL SIGNIFICANTLY
FAVORING PRECIPITATION TYPE TO BE SNOW. A BRIEF MIX MAY OCCUR AT
THE LEADING EDGE OF THIS TRANSITION. WITH THE ARRIVAL OF THE SNOW
WILL ALSO COME THE ONSET OF STRONG NORTHWEST WINDS. GUSTS TO NEAR
30 KTS ARE HIGHLY LIKELY...AND THE COMBINATION OF THAT AND FALLING
SNOW WILL LIKELY LEAD TO REDUCED VISIBILITY TO 1SM OR EVEN LOWER
FOR A WHILE NEAR MIDDAY. WHILE THE CEILINGS WILL IMPROVE SLOWLY
DURING THE AFTERNOON...THE SNOW SHOULD LAST UNTIL 21Z-23Z OR SO
BEFORE ENDING. SCATTERING IS LIKELY DURING THE EVENING. MTF
//ORD AND MDW CONFIDENCE...UPDATED 08Z...
* HIGH CONFIDENCE REGARDING CIGS THROUGH DAYBREAK...MEDIUM
CONFIDENCE LATER THIS MORNING...LOW CONFIDENCE THIS AFTERNOON.
* HIGH CONFIDENCE REGARDING RAIN EARLY THIS MORNING.
* HIGH CONFIDENCE REGARDING SNOW LATER THIS MORNING INTO THIS
AFTERNOON...LOW CONFIDENCE REGARDING SPECIFICS ON TIMING...
VIS/CIGS AND AMOUNTS.
* MEDIUM CONFIDENCE REGARDING WIND SPEEDS/GUSTS/DURATION. CMS
//OUTLOOK FOR ORD/MDW FOR 12Z WEDNESDAY-12Z MONDAY...UPDATED 00Z...
WEDNESDAY...VFR. MVFR AND GUSTY WEST NORTHWEST WINDS DEVELOPING
DURING THE NIGHT.
THURSDAY...MVFR POSSIBLE. GUSTY NORTHWEST WINDS.
FRIDAY...MVFR...WITH IFR POSSIBLE. CHANCE OF SNOW.
SATURDAY...SLIGHT CHANCE OF RAIN/SNOW.
SUNDAY...SLIGHT CHANCE OF RAIN OR SNOW DURING THE NIGHT.
MTF
&&
.MARINE...
254 AM CST
LOW PRESSURE CONTINUES TO LIFT NORTHEAST ACROSS CENTRAL
QUEBEC...WITH A TRAILING AND NEARLY STATIONARY FRONTAL BOUNDARY
EXTENDING SOUTHWEST THROUGH NORTHWEST IN/CENTRAL IL. A SERIES OF
WEAK LOW PRESSURE HAVE MOVED ALONG THIS BOUNDARY...HOWEVER GUIDANCE
IS INDICATING THAT TODAY THE BOUNDARY WILL BEGIN TO ADVANCE
EAST/SOUTHEAST AS A PUSH OF MUCH COLDER AIR ARRIVES. EARLY THIS
MORNING OBSERVATIONS HAVE INDICATED WIND GUSTS BETWEEN 10 TO 20 KT
GENERALLY FROM THE NORTH. WITH THE LACK OF A SIGNIFICANT PRESSURE
GRADIENT EARLY THIS MORNING WINDS SHOULD REMAIN LIGHT FOR A BRIEF
PERIOD OF TIME...BEFORE STEADILY RAMPING UP TOWARDS GALES FOR THE
OPEN WATERS AND SOLID SMALL CRAFT CONDITIONS FOR THE NEARSHORE
WATERS.
GUIDANCE HAS CONTINUED TO FOCUS ON A 15-18Z WINDOW FOR WINDS PUSHING
TO 35-40KT ACROSS THE OPEN WATERS OF LAKE MICHIGAN. SREF NEAR SFC
WIND PLUMES HAVE SUGGESTED WINDS AT 18Z WILL BE SUSTAINED ARND 20KT.
THIS COUPLED WITH A HIGH CONFIDENCE OF THE MIXED LAYER BRINGING TO
THE SFC WINDS ARND 850MB OF 40-45KT...SUGGEST HEAVILY THAT GALES
CONFIDENCE IS NEAR 100 PERCENT. THEN BASED ON OPERATIONAL MODELS AND
ENSEMBLES WINDS RAPIDLY DECLINE BY 06Z WED TO ARND 10-20KT
SUSTAINED...AND GUSTS TO 30KT. THIS SHOULD BRING AN END TO THE
GALES...HOWEVER INFREQUENT GALES TO 35KT MAY OCCUR FOR A FEW HOURS
AFT 06Z WED. SMALL CRAFT CONDITIONS WILL PERSIST FOR THE NORTHWEST
INDIANA WATERS THROUGH WED MORNING UNDER A NW FLOW AND ELEVATED
WAVES.
HIGH PRESSURE QUICKLY BUILDS IN FROM THE WEST/SOUTHWEST...AND SHOULD
RELAX WINDS FOR THE REMAINDER OF THE NIGHT INTO EARLY WED. THEN YET
ANOTHER SYSTEM IS PROGGED TO DEVELOP WED NGT AS THE HIGH PRESSURE
DRIFTS EAST. THIS WILL ALLOW A TIGHTENING PRESSURE GRADIENT LATE WED
AS WINDS BACK TO THE SOUTHWEST. CURRENT INDICATIONS ARE THAT LOW END
GALES ARE POSSIBLE EARLY THUR MORNING. THEN A BROAD HIGH PRESSURE
AREA BUILDS IN FROM THE NW AND SHUD PROVIDE A PERIOD OF LIGHTER
WINDS FOR FRI. THEN WINDS SHUD QUIET DOWN FOR A FEW PERIODS. THEN
FOR THE SECOND HALF OF THE UPCOMING WEEKEND...MUCH WARMER AIR MAY
SLIDE OVER LAKE MICHIGAN SUN. THIS HAS THE POTENTIAL OF CREATING A
RARE LATE JANUARY STABLE MARINE ENVIRONMENT SUN. CONFIDENCE AT THIS
JUNCTURE IS VERY LOW...HOWEVER SOME CONSISTENCY HAS BEEN NOTED
AMONGST FORECAST SOLUTIONS.
BEACHLER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...9 AM TUESDAY TO 10 PM
TUESDAY.
SMALL CRAFT ADVISORY...ILLINOIS NEARSHORE WATERS UNTIL 9 AM WEDNESDAY.
SMALL CRAFT ADVISORY...LMZ743-LMZ744-LMZ745...9 AM TUESDAY TO
NOON WEDNESDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1210 AM CST TUE JAN 17 2012
.AVIATION...
PCPN SPREADING NE OVRNGT AS FRONT CONTINUES TO SLIDE THROUGH THE
CWA. EXPECTING RAIN OR FREEZING RAIN TRANSITIONING OVER TO
SNOW WITH SOME MINOR ICE ACCUMULATIONS POSSIBLE AT KCID/KDBQ/KMLI.
SNOW WILL BE OVERSPREADING TERMINALS AFT 09Z-15Z AND COULD BE
MODERATE TO BRIEFLY HEAVY AT TIMES REDUCING VSBY TO AROUND 1/2
MILE MAINLY KCID AND KDBQ TUE AM. OTRW VSBYS GENERALLY 1-5SM IN
-SN TUE AM WITH SNOW DIMINISHING LATE AM THROUGH MIDDAY. WINDS TO
BECOME NW WINDS AND INCREASE OVRNGT WITH GUSTS OF 25-30 KTS
DEVELOPING TUE AM THROUGH TUE AFTN... WITH SOME REDUCED VSBYS IN
BLOWING/DRIFTING SNOW POSSIBLE. OVERALL CONDITIONS DETERIORATING
NEXT 6-12 HRS TO MVFR/IFR WITH POTENTIAL FOR LIFR CONDITIONS AT
KCID AND KDBQ FOR A TIME TUE AM. STRONG SUBSIDENCE IN WAKE OF
UPPER LEVEL DISTURBANCE TO BRING CLEARING BY MID AFTN THROUGH
EARLY EVE WITH VFR CONDITIONS.
&&
.PREV DISCUSSION... /ISSUED 1004 PM CST MON JAN 16 2012/
UPDATE...
SNOW COULD MAKE FOR MESSY COMMUTE TUE AM OVER NORTHEAST IA INTO NW
IL.
PCPN BLOSSOMING OVER KS/MO AS SHORTWAVE LIFTS E/NE ALONG FRONTAL
ZONE. HEAVIEST PCPN TO STAY TO OUR SOUTH BUT SOME LIGHT PCPN
TO SPREAD E/NE ALONG ELEVATED 925-850 FRONTAL ZONE OVER THE
SOUTHEAST CWA. TEMPS WARM ENOUGH FOR ALL LIQUID AND SFC TEMPS
ABOVE FREEZING FOR MOSTLY RAIN. ADDITIONAL LIFT FROM SHORTWAVE
SHIFTING INTO CENTRAL PLAINS SHOULD BRING SNOW ACROSS THE
CWA LATER TNGT AND TUE AM. MODELS SHOWING SOME PRETTY STRONG
OMEGAS IN DENDRITIC GROWTH ZONE AND SUFFICIENT FORCING ALBEIT
FOR SHORT DURATION BUT SUFFICIENT FOR POTENTIAL SWATH OF 1-3
INCHES WITH FAVORED AXIS ROUGHLY NORTH OF KSQI-KMLI-KIOW LINE
PER WARM ADVECTION WING AND TRACK OF H85 LOW. CANT RULE OUT EVEN
SOME LOCALIZED AMOUNTS NEAR 4 INCHES IF MODELS VERIFY. SNOW
COULD HAVE AN IMPACT ON MORNING COMMUTE AS LOOKS TO BE PRIME-TIME
FOR FORCING. HAVE NUDGED UP SNOW AMOUNTS NORTH OF THE ABOVE
MENTIONED AXIS. WITH WEAK SFC LOW NOT MOVING MUCH FROM CENTRAL
IL TEMPS AND ONSET OF STRONG COLD ADVECTION DELAYED AND SO HAVE
REDUCED SNOW AND FREEZING PCPN MENTION SOUTHEAST... AND TWEAKED
UP MINS.
PREV DISCUSSION... /ISSUED 328 PM CST MON JAN 16 2012/
SYNOPSIS...
A COLD FRONT EXTENDED FROM NORTHERN LK MI SOUTHWEST THROUGH EASTERN
IOWA TO LOW PRESSURE OVER NORTHWEST MO LATE THIS AFTERNOON. SO FAR
NOT PRECIPITATION WAS OCCURRING IN THE VICINITY OF FRONT OR SURFACE
IN OR NEAR THE MID MISSISSIPPI VALLEY. THERE WAS STRONG THERMAL
GRADIENT RANGING FROM THE MID AND UPPER 60S OVER THE NORTHEAST
QUARTER OF MO TO THE MID 30S OVER NORTHEAST IOWA. LOW LEVEL
MOISTURE WAS STREAMING NORTH AHEAD OF THE LOW/FRONT WITH
WIDESPREAD MID AND UPPER 40 DEWPOINTS OVER MUCH OF NORTHEAST MO
INTO WEST CENTRAL IL. THE MIDWEST FRONT WAS SETUP AHEAD OF A 500MB
S/W TROF THAT WAS MOVING ACROSS THE CENTRAL/NORTHERN ROCKIES AT
18Z PER RUC PROGS AND WATER VAPOR IMAGERY.
SHORT TERM...TONIGHT AND TUESDAY...
A CHALLENGING FORECAST FOR THE OVER NIGHT HOURS WITH THE STRONG
COLD FRONT OVER THE AREA THIS EVENING DROPPING SOUTHEAST THROUGH
THE CWFA BY LATE EVENING. THEN SOME MID-LEVEL ENERGY MOVING
THROUGH LATE TONIGHT AFTER THE LOW LEVEL COLD AIR IS IN PLACE.
TUESDAY LOOKS LIKE A RAW WINDY DAY WITH STRONG CAA AND LINGER
FLURRIES OR LIGHT SNOW.
SO FAR WITH THIS SYSTEM PRECIPITATION HAS BEEN NON
EXISTENT...HOWEVER THAT APPEARS TO BE CHANGING AS WE GO INTO THE
OVERNIGHT HOURS. MODEL SOUNDINGS CONTINUE TO SHOW THE LOW LEVELS
SATURATING THIS EVENING WHICH SHOULD OCCUR AS THE COLD LOW LEVEL
AIR MOVES IN BEHIND THE FRONT THIS EVENING. SOME FORCING WILL BE
PRESENT IN THE LOW LEVELS IN THE FORM OF FGEN AT THE SAME TIME
MID/UPPER LEVEL RH WILL BE INCREASING AND COULD PROVIDE A FEEDER
MECHANISM FOR THE LOW CLOUDS...SO WENT WITH LOW POPS FOR LIGHT
PRECIPITATION THIS EVENING AS OPPOSED TO DRIZZLE. IF
PRECIPITATION OCCURS BEFORE MIDNIGHT THEN THE THERMAL PROFILES
WOULD FAVOR RAIN OVER THE SOUTHEAST HALF OF THE CWFA WITH A MIX OF
FZRA/SN OVER THE NORTHWEST HALF. BETTER FORCING WILL MOVE OVER THE
AREA AFTER MIDNIGHT WITH MID/UPPER FGEN INCREASING AHEAD OF VORT
MAX MOVING OUT OF THE WESTERN TROF. THE FGEN WILL BE CO-LOCATED
WITH A POCKET OF STEEPER MID LEVEL LAPSE RATES WHICH SUPPORTS A
NARROW BAND OF ENHANCED PRECIPITATION MAINLY FROM THE SOUTHWEST
CWA INTO NW IL. THERE MAY BE SOME FREEZING RAIN MIXED WITH THE
PRECIPITATION JUST AFTER MIDNIGHT BUT THE COLD AIR SHOULD DEEPEN
ENOUGH BY 09Z FOR ALL SNOW OVER THE CWFA. THE SNOW WILL LINGER
INTO THE MORNING AND END DURING THE AFTERNOON IN THE SOUTHWEST
WITH LINGERING FLURRIES IN THE NORTHEAST. BY TUESDAY AFTERNOON
SNOWFALL AMOUNTS ARE EXPECTED TO BE IN THE 1 TO 2 INCH RANGE OVER
THE NORTHWEST HALF WITH LESS THAN AN INCH IN THE SOUTHEAST HALF OF
THE CWFA. NORTHWEST WINDS GUSTING TO 25 TO 30 MPH TUESDAY MAY
CAUSE SOME BLOWING AND DRIFTING. OVERNIGHT TEMPERATURES SHOULD
FALL INTO THE TEENS NORTHWEST TO MID 20S SOUTHEAST. ONGOING STRONG
LOW LEVEL CAA AND CLOUDS WILL ALLOW TEMPERATURES TO CONTINUE
FALLING DURING THE DAY AND SHOULD BE IN THE TEENS BY MID AFTERNOON
OVER ALL BUT THE SOUTHWEST CORNER WHERE LOW TO MID 20S ARE
ANTICIPATED. ..DLF..
LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
TUESDAY NIGHT AND WEDNESDAY...LOOKING AT THE LATEST AVAILABLE
12Z RUN MODEL GUIDANCE...CLEARING AND COLD CONDITIONS STILL ON
TRACK FOR TUE NIGHT IN SUBSIDENCE WAKE OF THE EXITING GRT LKS SYSTEM
AND ARRIVAL OF LLVL RIDGE LOBE. SOME LOWS BELOW ZERO POSSIBLE IN
AREAS NORTH OF I80/FAVORED VALLEY REGIONS...OTHERWISE OTHER AREAS
TO BE IN THE SINGLE DIGITS ABOVE ZERO. THESE LATEST 12Z RUNS STILL
SUGGEST AN UPPER LEVEL WAVE WILL PROPAGATE OUT OF THE ACTIVE
PACIFIC NW REGION AND PASS ACRS PORTIONS OF MN AND WI CLIPPER-
STYLE IN FRESHLY ESTABLISHED BROAD NORTH-WESTERLIES...TO USHER YET
ANOTHER FRONT INTO THE CWA BY LATE WED NIGHT AND INTO THU MORNING.
STILL APPEARS A POSSIBILITY OF OR EVEN POST-FRONTAL LIGHT SNOW IN
MUCH OF THE CWA WED NIGHT AND INTO THU MORNING. FOR NOW...WILL ADD
A SLIGHT CHC FOR MEASURABLE SNOW IN THE FAR NORTHEASTERN CWA BUT
ADD FLURRIES FOR MUCH OF THE REMAINDER OF THE FCST AREA. THE 12Z
GFS REMAINS THE QUICKEST SOLUTION IN HANDLING THE FROPA MAKING IT
TO THE WESTERN OH RVR VALLEY BY 12Z THU AND POST-FRONTAL COLD RUSH
WELL IMPLANTED ACRS THE LOCAL AREA...BUT OTHER MODELS INCLUDING
THE ECMWF HAVE SPED UP THIS PROCESS AS WELL. THUS IT APPEARS A
COLD BLUSTERY LATE WED NIGHT-THU MORNING COULD BE IN STORE WITH
LOW SINGLE DIGIT LOWS BY DAWN THU AND WIND CHILLS IN THE DOUBLE
DIGITS BELOW ZERO.
THURSDAY THROUGH FRIDAY...ONGOING LIGHT SNOW AND FLURRIES TO
START THE PERIOD OFF THU MORNING...BUT AGAIN NORTHWEST WINDS IN
STOUT CAA/INCOMING SFC RIDGE PRESSURE GRADIENT COULD BE GUSTING OVER
30 MPH AND PRODUCING DOUBLE DIGIT BELOW ZERO WIND CHILL VALUES
THROUGH AT LEAST MID MORNING. PASSING 1025+ MB COLD HIGH PRESSURE
SYSTEM WITH ORIGINS FROM WESTERN CANADA WILL THEN SCOUR THINGS OUT
FOR THE REST OF THE DAY AND INTO THU EVENING BEFORE HIGH CLOUDS
INCREASE AGAIN FROM THE WEST AHEAD OF THE NEXT POTENTIAL SYSTEM. LLVL
BAROCLINICITY STILL TO GET ALIGNED PARALLEL UNDER THE DEVELOPING MEAN
FLOW NORTH-WESTERLIES ACRS OR NEAR THE DVN CWA ON THU AND TIGHTENING
UP AS THE PERIOD PROGRESSES. LATEST MEDIUM RANGE MODEL RUNS CONTINUE
TO PICK UP ON A MORE SUBSTANTIAL TYPE CLIPPER-LIKE WAVE PROPAGATING
DOWN IN THIS FLOW ALONG THE LLVL THERMAL RIBBON TOWARD WEEKS END.
THIS SYSTEM WILL LOOK TO UTILIZE SOME GULF MOISTURE FEED FROM
THE SOUTH...BUT THE MODELS CONTINUE TO VARY FROM RUN-TO-RUN ON HOW
FAR NORTH OR SOUTH THIS FEATURE WILL TRACK AS WELL AS INCOMING SPEED.
THEY STILL SUGGEST A WAVE STRONG ENOUGH TO PRODUCE 1-3 OR EVEN 2-4
INCHES OF SNOW SOMEWHERE IN THE REGION...WITH THE LATEST 12Z RUN
GFS NOW MAKING A DIRECT HIT ON THE CWA FROM LATE THU NIGHT INTO
FRI MORNING WITH WIDESPREAD 2-4 INCHES BY 18Z FRI BEFORE THE
SYSTEM SHUTTLES OFF TO THE EAST. THE NEW 12Z ECMWF IS NOW SLOWER
AND FURTHER NORTH...SUGGESTING A DRY THU NIGHT AND THEN ACCUMULATING
SNOWS OF 2-5+ INCHES MAINLY ACRS MN/NE IA AND SOUTH HALF OF WI ON
FRI. THE EURO DOES TRY TO DO SOME PHASING/DIGGING RIGHT OVER AND
JUST SOUTHEAST OF THE DVN CWA LATER FRI WHICH MAY THEN WRAP SOME
ACCUMULATING SNOWS BACK ON THE NORTHEASTERN AND NORTHERN CWA FRI
AFTERNOON AND INTO THE EVENING WITH ACCUMULATIONS POSSIBLE.
INTERESTING THAT THE LATEST RUNS ARE LESS BULLISH ON THE EXTENT OF
WARM DRAW FROM THE SOUTH SO FOR NOW WILL JUST ADVERTISE ALL SNOW
ON FRI INSTEAD OF A MIX IN THE SOUTH. BUT THERE IS TIME FOR LATER
RUNS TO AGAIN CHANGE ON THAT ASPECT. WILL KEEP MODERATE CHC POPS
GOING ALONG WITH THE SNOW WORDING ON FRI FOR NOW.
SATURDAY THROUGH MONDAY...LONG RANGE SIGNALS/ENSEMBLES AND TRENDS ON
PROJECTED H5 MB GEOPOTENTIAL HEIGHT FIELDS SUGGEST L/W TROF ENERGY TO
DIG ACRS THE WESTERN COAST...WITH RESULTANT FLATTENING FLOW TO MID
CONUS RIDGING TAKING PLACE BEHIND THE EXITING FRI SYSTEM OVER THE
WEEKEND. STRONG THERMAL MODERATION SIGNALS ARE THERE WITH A TAP INTO
ANOTHER ROUND OF BUILDING WARM POOL ACRS THE SOUTHERN PLAINS BY
SUNDAY...AS OPPOSED TO SAT WHICH NOW DOES NOT APPEAR WILL BE AS
MILD AFTER A COLD START/FRI NIGHT AND SOME DELAY IN RETURN FLOW.
THERMAL PROFILES ARE ALMOST THERE TO SUPPORT HIGHS NEAR 50 BY NEXT
SUNDAY WITH ENOUGH MIXING AND INSOLATION...BUT MUCH WILL DEPEND ON
ANY NEW SNOW COVER FROM THE FRI SYSTEM AND MOISTURE RETURN GOING INTO
CLOUD PRODUCTION LIMITING THE WARM UP POTENTIAL WHICH IS COMMON IN
THIS TYPE OF WAA SCENARIO. WILL TAKE THE PRECIP OUT FOR NEXT SUNDAY
UNDER THE EXPECTED THERMAL RIDGE...BUT NOT GO QUITE AS WARM AS THE
POTENTIAL IS FOR NOW....UPPER 30S IN THE FAR NORTH TO THE MID/UPPER
40S ALONG AND SOUTH OF I80. MODEL DISCREPANCIES AND PHASING ISSUES
APLENTY IN HANDLING EVENTUAL IN-LAND PROPAGATING WAVE ENERGY OUT OF
THE WESTERN TROFFINESS FOR LATE IN THE WEEKEND AND INTO EARLY NEXT
WEEK. BUT LOOKING AT LONG RANGE UPPER JET PLACEMENT AND AIRMASS
STEERING MECHANISMS THE ABOVE NORMAL THERMAL REGIME STILL LOOKS LIKE
IT WILL BE WELL IN PLACE BY THE TIME THESE WAVE SYSTEM AND ASSOCIATED
SFC FEATURES TRY TO PUSH ACRS THE MIDWEST. THUS MAINLY A RAIN THREAT
FOR THE MONDAY PERIOD...BUT CONFIDENCE ON THIS TIMING LOW. THE ECMWF
ACTUALLY PUSHES A FRONT THROUGH THE CWA SUNDAY NIGHT WITH A RAIN
THREAT...AND THEN IS DRY AND COOLER FOR MONDAY AS THE NEXT LARGE
SYSTEM ORGANIZES UPSTREAM AND LOOMS OVER THE GRT BSN/SW PLAINS WITH
THOUGHTS OF IMPACTING THE MIDWEST BY MID NEXT WEEK. ..12..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1004 PM CST MON JAN 16 2012
.UPDATE...
SNOW COULD MAKE FOR MESSY COMMUTE TUE AM OVER NORTHEAST IA INTO NW
IL.
PCPN BLOSSOMING OVER KS/MO AS SHORTWAVE LIFTS E/NE ALONG FRONTAL
ZONE. HEAVIEST PCPN TO STAY TO OUR SOUTH BUT SOME LIGHT PCPN
TO SPREAD E/NE ALONG ELEVATED 925-850 FRONTAL ZONE OVER THE
SOUTHEAST CWA. TEMPS WARM ENOUGH FOR ALL LIQUID AND SFC TEMPS
ABOVE FREEZING FOR MOSTLY RAIN. ADDITIONAL LIFT FROM SHORTWAVE
SHIFTING INTO CENTRAL PLAINS SHOULD BRING SNOW ACROSS THE
CWA LATER TNGT AND TUE AM. MODELS SHOWING SOME PRETTY STRONG
OMEGAS IN DENDRITIC GROWTH ZONE AND SUFFICIENT FORCING ALBEIT
FOR SHORT DURATION BUT SUFFICIENT FOR POTENTIAL SWATH OF 1-3
INCHES WITH FAVORED AXIS ROUGHLY NORTH OF KSQI-KMLI-KIOW LINE
PER WARM ADVECTION WING AND TRACK OF H85 LOW. CANT RULE OUT EVEN
SOME LOCALIZED AMOUNTS NEAR 4 INCHES IF MODELS VERIFY. SNOW
COULD HAVE AN IMPACT ON MORNING COMMUTE AS LOOKS TO BE PRIME-TIME
FOR FORCING. HAVE NUDGED UP SNOW AMOUNTS NORTH OF THE ABOVE
MENTIONED AXIS. WITH WEAK SFC LOW NOT MOVING MUCH FROM CENTRAL
IL TEMPS AND ONSET OF STRONG COLD ADVECTION DELAYED AND SO HAVE
REDUCED SNOW AND FREEZING PCPN MENTION SOUTHEAST... AND TWEAKED
UP MINS.
&&
.PREV DISCUSSION... /ISSUED 603 PM CST MON JAN 16 2012/
AVIATION...
CONDITIONS EXPECTED TO DETERIORATE LATER THIS EVE AND OVRNGT AS
COLD FRONT MOVES THROUGH WITH VFR CONDITIONS GIVING WAY TO
MVFR AND IFR CONDITIONS IN POSSIBLY A WINTRY MIX OF VERY LIGHT
RAIN OR DRIZZLE OR FREEZING DRIZZLE AND SNOW. PCPN EXPECTED TO GO
OVER TO ALL SNOW LATE TNGT AND PERSIST THROUGH TUE AM AS AN
UPPER LEVEL DISTURBANCE PASSES... WITH SOME ACCUMULATIONS
LIKELY AT KDBQ/KCID/KMLI. NW WINDS WILL BE INCREASING OVRNGT
WITH GUSTS OF 25-30 KTS DEVELOPING MID-LATE TUE AM THROUGH TUE
AFTN... WITH SOME REDUCED VSBYS IN BLOWING/DRIFTING SNOW POSSIBLE
MAINLY AT KDBQ. STRONG SUBSIDENCE IN WAKE OF DEPARTING DISTURBANCE
TUE AFTN TO LIKELY BRING RAPID CLEARING BY MID TO LATE TUE AFTN.
PREV DISCUSSION... /ISSUED 328 PM CST MON JAN 16 2012/
SYNOPSIS...
A COLD FRONT EXTENDED FROM NORTHERN LK MI SOUTHWEST THROUGH EASTERN
IOWA TO LOW PRESSURE OVER NORTHWEST MO LATE THIS AFTERNOON. SO FAR
NOT PRECIPITATION WAS OCCURRING IN THE VICINITY OF FRONT OR SURFACE
IN OR NEAR THE MID MISSISSIPPI VALLEY. THERE WAS STRONG THERMAL
GRADIENT RANGING FROM THE MID AND UPPER 60S OVER THE NORTHEAST
QUARTER OF MO TO THE MID 30S OVER NORTHEAST IOWA. LOW LEVEL
MOISTURE WAS STREAMING NORTH AHEAD OF THE LOW/FRONT WITH
WIDESPREAD MID AND UPPER 40 DEWPOINTS OVER MUCH OF NORTHEAST MO
INTO WEST CENTRAL IL. THE MIDWEST FRONT WAS SETUP AHEAD OF A 500MB
S/W TROF THAT WAS MOVING ACROSS THE CENTRAL/NORTHERN ROCKIES AT
18Z PER RUC PROGS AND WATER VAPOR IMAGERY.
SHORT TERM...TONIGHT AND TUESDAY...
A CHALLENGING FORECAST FOR THE OVER NIGHT HOURS WITH THE STRONG
COLD FRONT OVER THE AREA THIS EVENING DROPPING SOUTHEAST THROUGH
THE CWFA BY LATE EVENING. THEN SOME MID-LEVEL ENERGY MOVING
THROUGH LATE TONIGHT AFTER THE LOW LEVEL COLD AIR IS IN PLACE.
TUESDAY LOOKS LIKE A RAW WINDY DAY WITH STRONG CAA AND LINGER
FLURRIES OR LIGHT SNOW.
SO FAR WITH THIS SYSTEM PRECIPITATION HAS BEEN NON
EXISTENT...HOWEVER THAT APPEARS TO BE CHANGING AS WE GO INTO THE
OVERNIGHT HOURS. MODEL SOUNDINGS CONTINUE TO SHOW THE LOW LEVELS
SATURATING THIS EVENING WHICH SHOULD OCCUR AS THE COLD LOW LEVEL
AIR MOVES IN BEHIND THE FRONT THIS EVENING. SOME FORCING WILL BE
PRESENT IN THE LOW LEVELS IN THE FORM OF FGEN AT THE SAME TIME
MID/UPPER LEVEL RH WILL BE INCREASING AND COULD PROVIDE A FEEDER
MECHANISM FOR THE LOW CLOUDS...SO WENT WITH LOW POPS FOR LIGHT
PRECIPITATION THIS EVENING AS OPPOSED TO DRIZZLE. IF
PRECIPITATION OCCURS BEFORE MIDNIGHT THEN THE THERMAL PROFILES
WOULD FAVOR RAIN OVER THE SOUTHEAST HALF OF THE CWFA WITH A MIX OF
FZRA/SN OVER THE NORTHWEST HALF. BETTER FORCING WILL MOVE OVER THE
AREA AFTER MIDNIGHT WITH MID/UPPER FGEN INCREASING AHEAD OF VORT
MAX MOVING OUT OF THE WESTERN TROF. THE FGEN WILL BE CO-LOCATED
WITH A POCKET OF STEEPER MID LEVEL LAPSE RATES WHICH SUPPORTS A
NARROW BAND OF ENHANCED PRECIPITATION MAINLY FROM THE SOUTHWEST
CWA INTO NW IL. THERE MAY BE SOME FREEZING RAIN MIXED WITH THE
PRECIPITATION JUST AFTER MIDNIGHT BUT THE COLD AIR SHOULD DEEPEN
ENOUGH BY 09Z FOR ALL SNOW OVER THE CWFA. THE SNOW WILL LINGER
INTO THE MORNING AND END DURING THE AFTERNOON IN THE SOUTHWEST
WITH LINGERING FLURRIES IN THE NORTHEAST. BY TUESDAY AFTERNOON
SNOWFALL AMOUNTS ARE EXPECTED TO BE IN THE 1 TO 2 INCH RANGE OVER
THE NORTHWEST HALF WITH LESS THAN AN INCH IN THE SOUTHEAST HALF OF
THE CWFA. NORTHWEST WINDS GUSTING TO 25 TO 30 MPH TUESDAY MAY
CAUSE SOME BLOWING AND DRIFTING. OVERNIGHT TEMPERATURES SHOULD
FALL INTO THE TEENS NORTHWEST TO MID 20S SOUTHEAST. ONGOING STRONG
LOW LEVEL CAA AND CLOUDS WILL ALLOW TEMPERATURES TO CONTINUE
FALLING DURING THE DAY AND SHOULD BE IN THE TEENS BY MID AFTERNOON
OVER ALL BUT THE SOUTHWEST CORNER WHERE LOW TO MID 20S ARE
ANTICIPATED. ..DLF..
LONG TERM...TUESDAY NIGHT THROUGH NEXT MONDAY...
TUESDAY NIGHT AND WEDNESDAY...LOOKING AT THE LATEST AVAILABLE
12Z RUN MODEL GUIDANCE...CLEARING AND COLD CONDITIONS STILL ON
TRACK FOR TUE NIGHT IN SUBSIDENCE WAKE OF THE EXITING GRT LKS SYSTEM
AND ARRIVAL OF LLVL RIDGE LOBE. SOME LOWS BELOW ZERO POSSIBLE IN
AREAS NORTH OF I80/FAVORED VALLEY REGIONS...OTHERWISE OTHER AREAS
TO BE IN THE SINGLE DIGITS ABOVE ZERO. THESE LATEST 12Z RUNS STILL
SUGGEST AN UPPER LEVEL WAVE WILL PROPAGATE OUT OF THE ACTIVE
PACIFIC NW REGION AND PASS ACRS PORTIONS OF MN AND WI CLIPPER-
STYLE IN FRESHLY ESTABLISHED BROAD NORTH-WESTERLIES...TO USHER YET
ANOTHER FRONT INTO THE CWA BY LATE WED NIGHT AND INTO THU MORNING.
STILL APPEARS A POSSIBILITY OF OR EVEN POST-FRONTAL LIGHT SNOW IN
MUCH OF THE CWA WED NIGHT AND INTO THU MORNING. FOR NOW...WILL ADD
A SLIGHT CHC FOR MEASURABLE SNOW IN THE FAR NORTHEASTERN CWA BUT
ADD FLURRIES FOR MUCH OF THE REMAINDER OF THE FCST AREA. THE 12Z
GFS REMAINS THE QUICKEST SOLUTION IN HANDLING THE FROPA MAKING IT
TO THE WESTERN OH RVR VALLEY BY 12Z THU AND POST-FRONTAL COLD RUSH
WELL IMPLANTED ACRS THE LOCAL AREA...BUT OTHER MODELS INCLUDING
THE ECMWF HAVE SPED UP THIS PROCESS AS WELL. THUS IT APPEARS A
COLD BLUSTERY LATE WED NIGHT-THU MORNING COULD BE IN STORE WITH
LOW SINGLE DIGIT LOWS BY DAWN THU AND WIND CHILLS IN THE DOUBLE
DIGITS BELOW ZERO.
THURSDAY THROUGH FRIDAY...ONGOING LIGHT SNOW AND FLURRIES TO
START THE PERIOD OFF THU MORNING...BUT AGAIN NORTHWEST WINDS IN
STOUT CAA/INCOMING SFC RIDGE PRESSURE GRADIENT COULD BE GUSTING OVER
30 MPH AND PRODUCING DOUBLE DIGIT BELOW ZERO WIND CHILL VALUES
THROUGH AT LEAST MID MORNING. PASSING 1025+ MB COLD HIGH PRESSURE
SYSTEM WITH ORIGINS FROM WESTERN CANADA WILL THEN SCOUR THINGS OUT
FOR THE REST OF THE DAY AND INTO THU EVENING BEFORE HIGH CLOUDS
INCREASE AGAIN FROM THE WEST AHEAD OF THE NEXT POTENTIAL SYSTEM. LLVL
BAROCLINICITY STILL TO GET ALIGNED PARALLEL UNDER THE DEVELOPING MEAN
FLOW NORTH-WESTERLIES ACRS OR NEAR THE DVN CWA ON THU AND TIGHTENING
UP AS THE PERIOD PROGRESSES. LATEST MEDIUM RANGE MODEL RUNS CONTINUE
TO PICK UP ON A MORE SUBSTANTIAL TYPE CLIPPER-LIKE WAVE PROPAGATING
DOWN IN THIS FLOW ALONG THE LLVL THERMAL RIBBON TOWARD WEEKS END.
THIS SYSTEM WILL LOOK TO UTILIZE SOME GULF MOISTURE FEED FROM
THE SOUTH...BUT THE MODELS CONTINUE TO VARY FROM RUN-TO-RUN ON HOW
FAR NORTH OR SOUTH THIS FEATURE WILL TRACK AS WELL AS INCOMING SPEED.
THEY STILL SUGGEST A WAVE STRONG ENOUGH TO PRODUCE 1-3 OR EVEN 2-4
INCHES OF SNOW SOMEWHERE IN THE REGION...WITH THE LATEST 12Z RUN
GFS NOW MAKING A DIRECT HIT ON THE CWA FROM LATE THU NIGHT INTO
FRI MORNING WITH WIDESPREAD 2-4 INCHES BY 18Z FRI BEFORE THE
SYSTEM SHUTTLES OFF TO THE EAST. THE NEW 12Z ECMWF IS NOW SLOWER
AND FURTHER NORTH...SUGGESTING A DRY THU NIGHT AND THEN ACCUMULATING
SNOWS OF 2-5+ INCHES MAINLY ACRS MN/NE IA AND SOUTH HALF OF WI ON
FRI. THE EURO DOES TRY TO DO SOME PHASING/DIGGING RIGHT OVER AND
JUST SOUTHEAST OF THE DVN CWA LATER FRI WHICH MAY THEN WRAP SOME
ACCUMULATING SNOWS BACK ON THE NORTHEASTERN AND NORTHERN CWA FRI
AFTERNOON AND INTO THE EVENING WITH ACCUMULATIONS POSSIBLE.
INTERESTING THAT THE LATEST RUNS ARE LESS BULLISH ON THE EXTENT OF
WARM DRAW FROM THE SOUTH SO FOR NOW WILL JUST ADVERTISE ALL SNOW
ON FRI INSTEAD OF A MIX IN THE SOUTH. BUT THERE IS TIME FOR LATER
RUNS TO AGAIN CHANGE ON THAT ASPECT. WILL KEEP MODERATE CHC POPS
GOING ALONG WITH THE SNOW WORDING ON FRI FOR NOW.
SATURDAY THROUGH MONDAY...LONG RANGE SIGNALS/ENSEMBLES AND TRENDS ON
PROJECTED H5 MB GEOPOTENTIAL HEIGHT FIELDS SUGGEST L/W TROF ENERGY TO
DIG ACRS THE WESTERN COAST...WITH RESULTANT FLATTENING FLOW TO MID
CONUS RIDGING TAKING PLACE BEHIND THE EXITING FRI SYSTEM OVER THE
WEEKEND. STRONG THERMAL MODERATION SIGNALS ARE THERE WITH A TAP INTO
ANOTHER ROUND OF BUILDING WARM POOL ACRS THE SOUTHERN PLAINS BY
SUNDAY...AS OPPOSED TO SAT WHICH NOW DOES NOT APPEAR WILL BE AS
MILD AFTER A COLD START/FRI NIGHT AND SOME DELAY IN RETURN FLOW.
THERMAL PROFILES ARE ALMOST THERE TO SUPPORT HIGHS NEAR 50 BY NEXT
SUNDAY WITH ENOUGH MIXING AND INSOLATION...BUT MUCH WILL DEPEND ON
ANY NEW SNOW COVER FROM THE FRI SYSTEM AND MOISTURE RETURN GOING INTO
CLOUD PRODUCTION LIMITING THE WARM UP POTENTIAL WHICH IS COMMON IN
THIS TYPE OF WAA SCENARIO. WILL TAKE THE PRECIP OUT FOR NEXT SUNDAY
UNDER THE EXPECTED THERMAL RIDGE...BUT NOT GO QUITE AS WARM AS THE
POTENTIAL IS FOR NOW....UPPER 30S IN THE FAR NORTH TO THE MID/UPPER
40S ALONG AND SOUTH OF I80. MODEL DISCREPANCIES AND PHASING ISSUES
APLENTY IN HANDLING EVENTUAL IN-LAND PROPAGATING WAVE ENERGY OUT OF
THE WESTERN TROFFINESS FOR LATE IN THE WEEKEND AND INTO EARLY NEXT
WEEK. BUT LOOKING AT LONG RANGE UPPER JET PLACEMENT AND AIRMASS
STEERING MECHANISMS THE ABOVE NORMAL THERMAL REGIME STILL LOOKS LIKE
IT WILL BE WELL IN PLACE BY THE TIME THESE WAVE SYSTEM AND ASSOCIATED
SFC FEATURES TRY TO PUSH ACRS THE MIDWEST. THUS MAINLY A RAIN THREAT
FOR THE MONDAY PERIOD...BUT CONFIDENCE ON THIS TIMING LOW. THE ECMWF
ACTUALLY PUSHES A FRONT THROUGH THE CWA SUNDAY NIGHT WITH A RAIN
THREAT...AND THEN IS DRY AND COOLER FOR MONDAY AS THE NEXT LARGE
SYSTEM ORGANIZES UPSTREAM AND LOOMS OVER THE GRT BSN/SW PLAINS WITH
THOUGHTS OF IMPACTING THE MIDWEST BY MID NEXT WEEK. ..12..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1120 PM CST MON JAN 16 2012
.AVIATION...
FOR THE 06Z TAF ISSUANCE...
SURFACE OBSERVATIONS ACROSS PORTIONS OF NORTHWEST KANSAS AT 02Z
INDICATING LIGHT SNOW WAS OCCURRING NEAR THE MID LEVEL BAROCLINIC
ZONE THAT WAS LOCATED AHEAD OF AN UPPER LEVEL TROUGH. AS OF 04Z
BASED ON THE LATEST WATER VAPOR LOOP THE NAM AND RUC SEEMED HAVE
A DECENT HANDLE WITH THIS UPPER LEVEL TROUGH AS IT CURRENTLY MOVES
EASTWARD TOWARDS WESTERN NEBRASKA AND WESTERN KANSAS. BASED ON THE
CURRENT TIMING AND TRACK OF THIS UPPER LEVEL TROUGH FROM THE
RUC/NAM ALONG WITH THE FORECAST LOCATION OF THE MID LEVEL
BAROCLINIC ZONE AND MOISTURE THERE WILL BE A CHANCE FOR SOME
LIGHT SNOW/FLURRIES AGAIN LATER THIS MORNING IN THE HAYS AREA BEFORE
12Z. FURTHER SOUTH LIFT APPEARS WEAKER. WINDS HOWEVER ARE EXPECTED
STAY UP BASED BOUNDARY LAYER WINDS AND 3HR SURFACE PRESSURE
CHANGE. BASED ON BUFR SOUNDINGS THE BASES THE CLOUDS OVERNIGHT
NIGHT ARE EXPECTED TO BRIEFLY LOWER TO AROUND 1500FT.
SUBSIDENCE WILL DEVELOP BEHIND AN UPPER LEVEL TROUGH AS IT MOVES
EAST OF THE AREA EARLY TUESDAY. IN ADDITION AN AREA OF HIGH
PRESSURE WILL BEGIN TO BUILD INTO THE AREA FROM THE NORTHWEST.
WINDS WILL SUBSIDE DURING THE DAY ON TUESDAY AS SKIES CLEAR. -RB
&&
PREV DISCUSSION... /ISSUED 400 PM CST MON JAN 16 2012/
SYNOPSIS...
A SHORTWAVE TROUGH WAS PROGRESSING ACROSS THE INTERMOUNTAIN WEST
THIS AFTERNOON. AHEAD OF THIS SYSTEM, A COLD FRONT PROGRESSED
THROUGH WESTERN KANSAS AND THEN STALLED EARLY THIS AFTERNOON
ALONG THE OKLAHOMA BORDER. THERE WAS A PRONOUNCED LOW-LEVEL THERMAL
GRADIENT ALONG THIS FRONT WITH TEMPERATURES NEAR 70F TO THE SOUTH
AND 30S/40S TO THE NORTH. TEMPERATURES WELL NORTH OF THE FRONT
OVER NORTHERN NEBRASKA AND SOUTH DAKOTA WERE IN THE TEENS. A
DRYLINE STRETCHED FROM NORTHWESTERN OKLAHOMA INTO SOUTHWESTERN
TEXAS. GULF MOISTURE WAS PROGRESSING INTO WESTERN AND NORTHERN
OKLAHOMA WITH DEWPOINTS IN THE 45 TO 55F RANGE.
DISCUSSION...
DAYS 1-2...
AS THE AFOREMENTIONED SHORTWAVE TROUGH APPROACHES THIS EVENING,
THERE WILL BE A PERIOD OF LIFT COLOCATED WITH A POCKET OF MOISTURE
AROUND 750-850MB ON THE COOL SIDE OF THE BOUNDARY. THE LEFT EXIT REGION
OF A JET STREAK ASSOCIATED WITH THE AFOREMENTIONED SHORTWAVE TROUGH
WILL BE ACROSS FAR NORTHERN KANSAS AND INTO NEBRASKA TONIGHT, AND
THIS IS WHERE ANY SUBSTANTIAL PRECIPITATION WILL BE. THE NAM/HRR
SHOW A SMALL AREA OF PRECIPITATION DEVELOPING WITH VERY LIGHT QPF
VALUES BETWEEN 00 AND 06 UTC FROM DODGE CITY TO GREAT BEND. THIS
COULD BE IN THE FORM OF LIGHT DRIZZLE, LIGHT FREEZING DRIZZLE OR
LIGHT SNOW. THIS PRECIPITATION WILL BE DEVELOPING BELOW A MID-
LEVEL INVERSION AND THE LAYER OF LIFT WILL BE FAIRLY SHALLOW. THIS
PRECIPITATION, THAT MAY NOT BE MEASURABLE, COULD BE OVER BEFORE
TEMPERATURES ARE COLD ENOUGH TO RESULT IN SLICK ROADS.
AFTER THIS SYSTEM PASSES LATE TONIGHT, SKIES WILL CLEAR AND
TEMPERATURES SHOULD HAVE NO PROBLEM FALLING INTO THE TEENS GIVEN
THE AFOREMENTIONED COLD AIR OVER THE NORTHERN PLAINS MOVING
SOUTHWARD. SO MOST OF THE COOLING TONIGHT WILL BE FROM COLD
ADVECTION AND MOT RADIATIONAL COOLING. WINDS MAY DROP OFF BY 12-13Z
AND THIS MAY ALLOW FOR SOME RADIATIONAL COOLING AS WELL.
TUESDAY WILL BE FAIRLY CHILLY AS COLD SURFACE HIGH PRESSURE SETTLES
INT CENTRAL KANSAS BY AFTERNOON. SO DESPITE THE SUNSHINE,
TEMPERATURES SHOULD HAVE TROUBLE GETTING MUCH ABOVE FREEZING FROM
DDC TO HAYS AND GCK. ANOTHER COLD NIGHT CAN BE EXPECTED TUESDAY NIGHT.
HOWEVER, LOW-LEVEL LEE TROUGHING WILL DEVELOP ALONG WITH ACCOMPANYING
25-30KT SOUTHWESTERLY WINDS AT 850MB. SO DESPITE THE COLD START,
THERE SHOULD BE ENOUGH VERTICAL MIXING TO DISCOURAGE STRONG
RADIATIONAL COOLING. ALSO, AS THE WINDS PICK UP, WARMER AIR
DEVELOPING FROM DOWNSLOPE FLOW ABOVE THE SURFACE WILL TEND TO MIX TO
THE SURFACE AND THIS WILL ALSO HELP TO KEEP TEMPERATURES A LITTLE
WARMER. BUT STILL, TEMPERATURES SHOULD FALL TO BETWEEN 15 AND 20F
AND THE 10 KT SOUTHERLY SURFACE WINDS WILL MAKE IT FEEL EVEN
COLDER.
A SHORTWAVE TROUGH WILL PROGRESS ACROSS THE NORTHERN PLAINS BY
WEDNESDAY WITH CONTINUED WEAK LEE TROUGHING ACROSS THE CENTRAL AND
SOUTHERN PLAINS. THE WEAK DOWNSLOPE FLOW ALONG WITH AMPLE SUNSHINE
SHOULD BE ENOUGH TO ALLOW TEMPERATURES TO WARM INTO THE UPPER 40S
TO LOWER 50S.
DAYS 3-7...
THE 12Z RUNS OF THE MEDIUM RANGE MODELS ARE ALL SHOWING A ZONAL FLOW
PATTERN ACROSS CENTRAL NORTH AMERICA WITH THE STRONGEST MID/UPPER
LEVEL FLOW ACROSS THE NORTHERN CONUS THROUGH MUCH OF THE EXTENDED
PERIOD. THE MODELS ARE ALL SHOWING FAST MOVING SHORTWAVE TROUGHS
MOVING THROUGH THE FLOW THAT WILL CROSS OVER THE CENTRAL PLAINS
WEDNESDAY NIGHT AND AGAIN ON FRIDAY.
THE WEDNESDAY SHORTWAVE TROUGH WILL MAINLY BE NORTH OF THE CENTRAL
HIGH PLAINS AND WILL HAVE LITTLE IMPACT...OTHER THAN A SHORT LIVED
WIND SHIFT. WITH THE SHORTWAVE TROUGH ON FRIDAY...THE ECMWF IS
SHOWING A LITTLE MORE AMPLITUDE THAN THE CANADIAN AND GFS MODELS BUT
EVEN IT DOESN`T PRODUCE ANY SIGNIFICANT PRECIPITATION AS THE
ATMOSPHERE OVER THE PLAINS WILL NOT BE OVERLY MOIST. THE BULK OF THE
COLDER AIR OVER THE NORTHERN PLAINS WILL IMPACT THE MIDWEST SO ANY
COOLDOWN WILL BE FAIRLY MINOR AS WESTERLY FLOW ALOFT CONTINUES. THE
REST OF THE EXTENDED PERIOD WILL CONTINUE TO BE DRY WITH
TEMPERATURES WARMING TO THE 50S AND 60S.
THE GFS AND ECMWF HAVE BEEN HINTING AT A STRONGER SHORTWAVE OR
CLOSED LOW DEVELOPING OVER THE WESTERN CONUS BY THE BEGINNING OF
NEXT WEEK. THE MODELS HAVE BEEN SHOWING A LOT OF INCONSISTENCY FROM
RUN TO RUN AND WITH EACH OTHER REGARDING THIS SO AM NOT OVERLY
CONFIDENT IN ANY MODEL SOLUTION AT THIS TIME.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 18 33 17 50 / 20 0 0 0
GCK 17 33 15 50 / 30 0 0 0
EHA 18 34 15 52 / 10 0 0 0
LBL 19 35 16 51 / 10 0 0 0
HYS 16 31 15 48 / 30 0 0 0
P28 23 35 17 49 / 30 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
536 PM EST TUE JAN 17 2012
.SYNOPSIS...
LOW PRESSURE WILL TRACK NORTHEAST ACROSS THE EASTERN GREAT LAKES
THIS EVENING...WITH THE ASSOCIATED COLD FRONT PUSHING THROUGH THE
MID ATLANTIC LATE TONIGHT INTO WEDNESDAY MORNING. HIGH PRESSURE
BUILDS INTO...AND THEN OVER THE REGION WEDNESDAY NIGHT THROUGH
THURSDAY. A WEAK TROUGH PASSES ACROSS THE REGION THURSDAY NIGHT
FOLLOWED BY A RETURN OF HIGH PRESSURE FRIDAY.
&&
.NEAR TERM /TONIGHT/...
QUICK UPDATE TO ACCOUNT FOR LATEST RADAR TRENDS THIS EVENING.
INCREASED POPS ACROSS WESTERN COUNTYS NEXT FEW HOURS IN RESPONSE
TO THE BAND OF SHOWERS QUICKLY APPROACHING THE AREA OUT AHEAD OF
THE COLD FRONT. LATEST RUC SEEMS TO HAVE THE BEST HANDLE WITH THESE
SHOWERS WITH THE HIGHEST POPS ACROSS WESTERN PIEDMONT COUNTYS THIS
EVENING. ALSO UPDATED HWO TO ACCOUNT FOR POTENTIAL WIND GUSTS TO
AROUND 40 MPH LATER TONIGHT WITH THE ACTUAL FROPA.
PREVIOUS DSCN:
THE LATEST WX ANALYSIS SHOWS A ~995 MB SURFACE LOW OVER SOUTHERN
ONTARIO WITH A COLD FRONT EXTENDING TO THE SW INTO THE MID-SOUTH
THIS AFTN. VIS/IR SATELLITE IMAGERY AND LIGHTING DATA REVEALS
CONVECTION NEAR THE LOW CENTER AND ALONG THE SURGING BOUNDARY OVER
EASTERN SECTIONS OF OH/KY. TO THE SOUTHEAST...LATEST REGIONAL
RADAR MOSAIC CONTINUES TO SHOW LIGHT WAA RAIN PULLING OFFSHORE
ATTM...WITH A BRIEF LULL IN POPS EXPECTED THROUGH THE EARLY
EVENING HOURS.
OTHER ISSUE OF NOTE TODAY IS THE GUSTY WINDS. AKQ VWP CONTINUES TO
INDICATE A 40-50 KT LOW LEVEL JET BETWEEN 2-3KFT AGL AT 20Z.
DESPITE DIURNAL LIFTING OF THE LLJ...GUSTY SW WINDS WILL CONTINUE
INTO THE EARLY EVENING HOURS. SUSTAINED WIND SPEEDS IN THE 20-25
MPH RANGE WL CONTINUE...W/FREQUENT GUSTS TO 30-35 MPH EXPECTED
THROUGH LATE AFTERNOON.
THE AFOREMENTIONED TROUGH RACES NORTHEAST INTO NORTHERN NEW
ENGLAND/SOUTHERN QUEBEC BY LATE TONIGHT, DRAGGING A STRONG COLD
FRONT THROUGH THE MID ATLANTIC AFTER MIDNIGHT TONIGHT INTO
WEDNESDAY MORNING. ADDITIONAL SHORTWAVE ENERGY, NOTED ON MID-
AFTERNOON SAT IMAGERY OVER THE CENTRAL GULF COAST, WILL TRIGGER A
WAVE ALONG THE FRONT. HIGH FORECAST CONFIDENCE REMAINS THAT THIS
FEATURE WILL ALLOW FOR ANOTHER PERIOD OF LIGHT RAIN ACROSS THE
REGION, WITH LIKELY TO CATEGORICAL POPS REMAINING FOR THE
TIDEWATER AND MOST OF NE NC...BUFFERED BY LOWER SHRA CHCS FARTHER
NORTH INTO RICHMOND METRO. QPF VALUES EXPECTED TO REMAIN QUITE
LIGHT...ON THE ORDER OF A QUARTER INCH OR LESS, WITH HIGHEST
AMOUNTS OVER NE NC. TEMPERATURES REMAIN VERY MILD THIS EVENING
MOST OF THE NIGHT AHEAD OF THE FRONT...BEFORE FALLING LATE. A
BRIEF PERIOD OF STRONGER WIND GUSTS IS POSSIBLE AS THE COLDER AIR
RUSHES IN.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
FRONT SLIDES OFFSHORE BY EARLY WEDNESDAY...WITH RAPID CLEARING
ENSUING THROUGH THE MORNING OVER THE WEST...REACHING THE COAST BY
EARLY TO MID AFTERNOON. HIGH TEMPERATURES WL LKLY BE ACHIEVED
EARLY IN THE DAY AND SHOULD GENERALLY RUN IN THE LOW TO MID 40S N
AND W...AND IN THE LOW 50S SE EARLY BEFORE FALLING INTO THE UPPER
40S LATE.
WED NIGHT-FRIDAY...
QUIET AND SEASONABLE CONDITIONS ARE EXPECTED WEDNESDAY NIGHT INTO
THURSDAY. A PERIOD OF PARTLY CLOUDY CONDITIONS WILL BE POSSIBLE
MAINLY ACROSS COASTAL SITES, AS A MOISTURE STARVED MID-LEVEL
TROUGH PASSES ACROSS THE REGION FOLLOWED BY A PERIOD OF CLEARING
THURSDAY MORNING AS HIGH PRESSURE MOVES OVERHEAD...SLIDING
OFFSHORE BY THURSDAY AFTERNOON. RESULTANT WAA THU AFTN/ EVENING WL
TRANSLATE TO INCREASING AFTN CLOUDINESS AHEAD OF NEXT SYSTEM AND
COLD FRONT APPROACH FROM THE WEST.
WEAK COLD FRONT LOOKS TO CROSS INTO THE AREA AS IT WEAKENS/WASHES
OUT FRIDAY MORNING. AS SUCH...EXPECT A CLOUDY NIGHT THU
NIGHT/EARLY FRIDAY AND LTL/NO PCPN WITH ITS PASSAGE. QUICK
CLEARING ONCE AGAIN BEHIND THE FRONT WITH CAA ON FRIDAY.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
MAIN FOCUS FOR THE LONG TERM PERIOD IS LO PRES TRAVERSING THE
EASTERN CONUS FRI INTO SAT. WAA PRECIP OUT AHEAD OF THIS SYSTEM WILL
BEGIN SAT MORNING THROUGH MIDDAY. WARMING TRENDS IN LO-LEVEL
THICKNESSES SUGGEST THAT THE PRECIP WILL START MSTLY AS RN...BUT
SOME MIXED PRECIP MAY MIX IN OVER FAR NORTHERN AREA BEFORE QUICKLY
CHANGING TO ALL RN. HAVE BUMPED UP POPS TO 60% ON SAT AS MODELS
HAVE CONTINUED TO SHOW GOOD TIME CONTINUITY W/ THIS SYSTEM. TEMPS ON
SAT MAY HAVE A LARGE NORTH TO SOUTH SPREAD W/ A WARM FRONT IN THE
VICINITY...CURRENT FORECAST CALLS FOR HIGHS THAT RANGE FROM THE
UPR 40S OVER NORTHERN PARTS OF THE FA TO NEAR 60 OVER NE NC.
MID-LEVEL S/W RIDGE DEVELOPS ON SUN ALLOWING TEMPS TO CLIMB INTO THE
THE MID 50S TO LWR 60S IN MOST SPOTS. WARMING TREND CONTINUES INTO
MON AS A S/W TROUGH MISSES TO THE NORTH AND UPPER HEIGHTS RISE. A LO
PRES SYSTEM APPROACHES FROM THE WEST MON NGT INTO TUE...BUT WILL
FORECAST SILENT POPS (20%) FOR NOW THIS FAR OUT IN TIME.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
LOW PRESSURE CENTERED OVER NORTHERN INDIANA EARLY THIS AFTERNOON
WITH A COLD FRONT EXTENDING INTO TX. A WARM FRONT ALSO EXTENDS
ACROSS THE MID ATL REGION WITH STRONG S-SW FLOW OVER THE AREA. WIND
GUSTS TO 20-30 KT EXPECTED THRU THE AFTERNOON AND EARLY EVENING. A
BAND OF LIGHT TO MODERATE SHOWERS WILL PASS THRU THE CWA THIS
AFTERNOON. EXPECT CONDITIONS TO GENERALLY STAY VFR WITH CEILINGS
AVERAGING 4000-7000 FT. RADAR SHOWING LITTLE PRECIP BETWEEN THIS
BAND AND SHOWERS ASSOCIATED WITH THE COLD FRONT.
THE COLD FRONT WILL PUSH INTO THE MID ATL REGION TONIGHT AND PASS
OFFSHORE BEFORE SUNRISE WEDNESDAY. SHOWERS SHOULD ACCOMPANY THE
FRONT AS IT MOVES THRU WITH GUSTY WINDS 20-30 KT AND HIGHER. WINDS
WILL SHIFT TO NW-N BEHIND THE FRONT AND START TO DIMINISH DURING THE
AFTERNOON. HIGH PRESSURE WILL BUILD IN WEDNESDAY AFTERNOON. VFR
CONDITIONS EXPECTED THRU FRIDAY.
&&
.MARINE...
LO PRES OVER THE EASTERN GREAT LAKES WILL PUSH INTO QUEBEC
TONIGHT...SLIDING A COLD FRNT THRU THE LOCAL AREA. AHEAD OF THE
FRNT...SCA CONDITIONS CONTINUE EVERYWHERE W/ SW WINDS 15-25 KT
GUSTING TO 30 KT. SEAS WILL BUILD TO 5-7 FT OVER THE LOWER EASTERN
SHORE COASTAL ZONES. THE FRNT SHOULD CLEAR THE WTRS BY 12Z...W/ AN
ENSUING QUICK CAA SURGE PRODUCING WINDS OCCASIONALLY UP TO GALE
FORCE. AT THIS POINT WILL STICK W/ THE CURRENT SCA IN EFFECT AND
WILL HANDLE ANY SHORT-DURATION GALE FORCE GUSTS W/ A SMW. NW WINDS
BEHIND THE FRNT WILL ALLOW SEAS OVER THE NC COASTAL ZONE TO
CONTINUE AT 4-6 FT UNTIL WED EVENG...SO WILL KEEP SCA IN EFFECT
UNTIL THEN. WINDS WILL STEADILY DIMINISH WED EVENG/NGT AS HI PRES
BLDS IN FM THE W. ANOTHER COLD FRNT CROSSES THE WTRS THU NGT
FOLLOWED BY A RETURN TO HI PRES FRI.
&&
.TIDES/COASTAL FLOODING...
ANOTHER ROUND OF BELOW NORMAL TIDES IS EXPECTED WITH THIS EVENING`S
LOW TIDE CYCLE. TIDAL LEVELS COULD REACH 1-1.5 FT BELOW MLLW.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST WEDNESDAY FOR ANZ630>634-
650-652-654-656.
SMALL CRAFT ADVISORY UNTIL 11 PM EST WEDNESDAY FOR ANZ658.
&&
$$
SYNOPSIS...MAM/AJZ
NEAR TERM...MPR/MAM
SHORT TERM...MAM/AJZ
LONG TERM...MAS
AVIATION...JEF
MARINE...MAS
TIDES/COASTAL FLOODING...MAS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
503 PM EST TUE JAN 17 2012
.SYNOPSIS...
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW STRONG UPR
DISTURBANCE IN THE MID MS RIVER VALLEY AND ACCOMPANYING SFC LO OVER
SRN LWR MI MOVING STEADILY TO THE E. ANOTHER DISTURBANCE IS A BIT
FARTHER N OVER MN. ALTHOUGH THE SHARPER DYNAMICS/WAD/MORE
SUBSTANTIAL MSTR ASSOCIATED WITH THE SOUTHERN DISTURBANCE IS
REMAINING TO THE S...ENHANCED H4-2 DVGC OVER THE CWA IN RRQ OF UPR
JET JUST S OF JAMES BAY AND THE UPR JET TO THE S THAT IS SUPPORTING
THE SOUTHERN SHRTWV AS WELL AS SLOPED FGEN ON THE COLD SIDE SYNOPTIC
FNT TO THE SE IS PROVIDING ENUF LIFT TO OVERCOME GENERAL CAD AT H85
TO BRING A WIDESRPEAD SN. THIS PCPN IS HEAVIEST IN THE N WIND SN
BELTS NEAR LK SUP WHERE THE INCOMING AIRMASS...H85 TEMPS AOB
-15C...IS CAUSING SOME ENHANCEMENT TO THE SN WITH UNIDIRECTIONAL N
WIND SHOWN ON THE MQT VWP THRU 8K FT MSL. SPOTTER NEAR IWD REPORTED
6-8 INCHES OF SN AS OF ABOUT 1630Z. HOWEVER...LATEST RADAR TRENDS
SHOW DIMINISHING MSTR/RETURNS ARRIVING W-E AS DISTURBANCES ARE
MOVING STEADILY E IN PROGRESSIVE UPR FLOW. UPSTREAM ARCTIC AIRMASS
IN MN IS QUITE DRY/STABLE PER 12Z INL RAOB...WHERE THE 12Z H85 TEMP
WAS -19C. SFC TEMPS ARE NOT MUCH ABV ZERO F IN THIS AREA...WITH
DEWPTS WELL BLO 0F.
&&
.SHORT TERM DISCUSSION /TNGT AND WED/...
MAIN FCST CONCERNS ARE LES TRENDS/AMOUNTS AND GOING HEADLINES/NEED
TO MAKE ANY ADJUSTMENTS TO THESE.
TNGT...AS PAIR OF DISTURBANCES/UPR JETS SHIFT TO THE E...SHRTWV RDG
AXIS/DRIER AIR IS PROGGED TO FOLLOW INTO THE UPR LKS. LINGERING
SYNOPTIC PCPN SHOULD DIMINISH LATE THIS AFTN OVER THE E WITH THE
ARRIVAL OF THE DRYING ALF AND RECENT RADAR TRENDS. ALTHOUGH THE
INCOMING AIRMASS WL BE MORE THAN SUFFICIENTLY COLD FOR LES WITH H85
TEMPS FALLING TO ARND -20C...THE DRYNESS/STABILITY OF THE UPSTREAM
AIRMASS AS WELL THE STEADILY BACKING WINDS ACCOMPANYING THE MOVEMENT
OF SFC HI PRES INTO THE MID MS RIVER VALLEY BY 12Z WED WL TEND TO
LIMIT LES AMOUNTS. FCST SDNGS FOR IWD SHOW INVRN BASE SINKING TO 2K
FT AGL BY 12Z WITH A SW SFC WIND...SO LES SHOULD END ENTIRELY THERE
BY THAT TIME. LES WL BE MORE RESILIENT E OF MQT WITH LONGER FETCH...
MORE PERSISTENT LLVL CNVGC AND INVRN BASE HANGING CLOSER TO 5K FT
MOST OF THE NGT. WITH BACKING LLVL FLOW/ARRIVAL OF DRIER AIR...
EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR W HALF...WHERE SOME
CLRG IS LIKELY GIVEN DRYNESS OF UPSTREAM AIRMASS.
AS FOR HEADLINES...PLAN TO ALLOW THE GOING WRNGS/ADVYS FOR THE W TO
EXPIRE AS SCHEDULED AT 00Z. OPTED TO CANX BARAGA COUNTY WITH
UNFAVORABLE NNW FLOW...BUT EXTENDED THE MQT ADVY UNTIL 00Z TO
ACCOUNT FOR LINGERING SHSN TOWARD THE ALGER COUNTY LINE. WL LET THE
ALGER ADVY GO THRU THE NGT WITH BULK OF SHSN SHIFTING INTO THAT
AREA. CONSIDERED A HEADLINE FOR NRN SCHOOLCRAFT AND LUCE COUNTIES AS
WELL...BUT THESE AREAS MISSED OUT ON THE BULK OF THE SN TDAY. WITH
SHIFTING WINDS TNGT... SUSPECT SN TOTALS IN THIS AREA WL BE LESS
THAN THE 3-5" INDICATED BY LES CHART FOR EXPECTED CONDITIONS EVEN
THOUGH THERE MAY BE PERIODS WHERE LLVL CNVGC IS ENHANCED BY LAND
BREEZE FLOW OFF ONTARIO.
WED...NEXT SHRTWV IN PROGRESSIVE FLOW ALF IS FCST TO MOVE FM THE NRN
PLAINS TO MN BY LATE IN THE DAY...WITH DVPA/WAD/DEEP LYR QVECTOR
CNVGC ARRIVING OVER THE W IN THE AFTN IN INCRSG SLY FLOW. WITH THE
BACKING FLOW...ANY LINGERING LES OVER THE KEWEENAW AND E OF GRAND
MARAIS WL SHIFT BACK INTO LK SUP. SINCE THE LO/MID LVLS WL BE
DRY...INITIAL DYNAMICS WL RESULT IN MAINLY THICKER MID/HI CLDS. WL
RETAIN GOING POPS ONLY FOR THE FAR W. WITH THE RETURN SSW FLOW OFF
LK MI...THERE COULD BE SOME LK CLDS/SHSN THERE AS WELL. BUT AIRMASS
APPEARS TOO DRY OVERALL TO SUPPORT MORE THAN LO CHC POPS.
.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
MODELS ARE IN AGREEMENT WITH THE NEXT SFC LOW TO BE POSITIONED OVER
WESTERN LS AT 00Z THURSDAY TO RESIDE OVER CENTRAL LS/CENTRAL UPPER
MI BY 06Z...AND JUST EAST OF THE CWA BY 12Z THURSDAY. THERE ARE
SMALL DIFFERENCES WHICH SHOULD BE SMOOTHED OUT WITH ANOTHER RUN OR
2. THE 17/09Z SRF WAS THE SLOWEST/MOST NW OF THE OPTIONS WHILE THE
GFS WAS THE FARTHEST SOUTH. ALL SOLUTIONS WHERE STILL UNDER THE
RHELM OF POSSIBILITY.
THE SFC LOW WILL BE ASSISTED EASTWARD BY A 500MB TROUGH SWINGING
FROM MN AT 00Z THURSDAY...SLIDING EAST OF UPPER MI BY MID MORNING
THURSDAY. EVEN THROUGH HIGH PRESSURE WILL ATTEMPT TO BUILD IN FROM
THE DAKOTAS ON THURSDAY...A TYPICIAL LINGERING SFC TROUGH CAN BE
EXPECTED OVER LAKE SUPERIOR THROUGH AT LEAST FRIDAY MORNING. THE
TROUGH SHOULD DIMINISH IN STRENGTH FRIDAY...BUT WILL QUICKLY BE
REPLACED BY ANOTHER TROUGH OUT AHEAD OF THE NEXT LOW PUSHING
EASTWARD FROM THE DAKOTAS.
THE COLDEST TEMPERATURES WILL LIKELY BE THURSDAY NIGHT INTO FRIDAY
MORNING...PARTICULARLY INTERIOR WEST IF CLOUDS CLEAR OUT AS MUCH AS
EXPECTED.
DAYS 4 THROUGH 7...SATURDAY THROUGH TUESDAY
DISAGREEMENTS REMAIN WITH THE HANDLING OF THE FEATURE FOR THIS
WEEKEND. AT 500MB THE ECMWF IS APPROX 6 HOURS QUICKER THAN THE GFS
BY SUNDAY MONRNING. ADDING TO THE ISSUES THE CANADIAN IS NEARLY FLAT
WITH THE INCOMING THROUGH...WHILE THE ECMWF/GFS SHOW SIMILAR
STRENGTH. IN SUPPORT OF THE ECMWF...THE 17/00Z ENSEMBLE RUNS OF THE
GFS WERE GENERALLY QUICKER THAN THE OPERATIONAL GFS.
LOOK FOR A DOMINANT RIDGE TO DEVELOP OVER THE CENTRAL AND SOUTHERN
PLAINS LATE IN THE WEEKEND...AND BUILD ACROSS THE UPPER GREAT LAKES
MONDAY...BEFORE SHIFTING TO THE EAST MONDAY NIGHT INTO EARLY
TUESDAY. MORE SIGNIFICANT DIFFERENCES CREEP IN MODEL WISE FOR
DAY7/TUESDAY. THE ECMWF STRENGTHENS THE 500MB TROUGH OFF THE WEST
COAST SUNDAY INTO A SIZABLE CUT OFF LOW ACROSS AZ/NM MONDAY
AFTERNOON THROUGH TUESDAY. THE GFS IS MUCH MORE PROGRESSIVE. EITHER
WAY...THE NEXT 500MB TROUGH WILL LIKELY SLIDE IN DURING THE DAY
TUESDAY.
&&
.AVIATION /FOR THE 18Z TAF ISSUANCE/...
DRIER AIR IS BEGINNING ITS PUSH INTO IWD ATTM PER RADAR IMAGERY AND
IWD OBSERVATIONS. THIS COMBINED WITH BACKING WINDS WILL ERODE LES
AND ALLOW VIS AND CIG TO RISE THIS AFTERNOON AND EVENING. ARRIVAL OF
DRIER AIR AT CMX AND SAW IS EXPECTED AROUND 20-21Z WITH BACKING AND
STRONGER WINDS. LOW LEVEL MOISTURE SHOULD STILL REMAIN AN ISSUE AT
ALL THREE SITES THROUGH 00Z BEFORE INCREASINGLY DRY AIR REMOVES
CLOUD COVER. HOWEVER...CMX COULD SEE LOW LEVEL CLOUDS AND LIGHT SNOW
SHOWERS REMAINING OVERNIGHT WITH FAVORED WESTERLY TO NORTHWESTERLY
FLOW. ALSO...EXPECT GUSTY WINDS UP TO 25KT THROUGH THIS EVENING AT
CMX AND SAW AS STRONGER WINDS AT 2-4KFT MIX TO THE SURFACE.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
EXPECT N WINDS UP TO 30 KTS EARLY THIS EVNG TO DIMINISH WITH
APPROACH OF HI PRES RIDGE FROM THE W. AS THIS HI CENTER SHIFTS TO
THE E WELL S OF THE UPPER LAKES...THE FLOW WILL ALSO BACK STEADILY
TO THE S ON WED AND INCREASE LATE IN THE DAY/EVNG AS ANOTHER LO PRES
CENTER MOVES TOWARD WESTERN LAKE SUP. ONCE THIS LO MOVES BY TO THE
E...A STRONG NW WIND WILL DRIVE BITTERLY COLD ARCTIC AIR OVER THE
AREA ON THU. THE MIXING ENHANCED BY THE CONSIDERABLE OVERWATER
INSTABILITY WILL DRAG STRONG NW WINDS TO THE SURFACE...SO MAINTAINED
GALE WATCH FOR WED NIGHT THRU THU. ALSO OPTED TO ISSUE HEAVY
FREEZING SPRAY WATCH FOR LATE WED NGT THRU THU NGT FOR ALL LK ZNS
WITH THE BITTERLY COLD AIR MOVING OVERHEAD. WINDS WILL DIMINISH AFT
THU NGT WITH WEAK PRES GRADIENT DOMINATING INTO THE WEEKEND.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING
FOR MIZ002-009.
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ005.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MIZ006.
LAKE SUPERIOR...
GALE WATCH FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY EVENING
FOR LSZ264-266-267.
HEAVY FREEZING SPRAY WATCH FROM THURSDAY MORNING THROUGH FRIDAY
MORNING FOR LSZ264>267.
GALE WATCH FROM WEDNESDAY EVENING THROUGH THURSDAY AFTERNOON FOR
LSZ162-263.
HEAVY FREEZING SPRAY WATCH FROM LATE WEDNESDAY NIGHT THROUGH
FRIDAY MORNING FOR LSZ162-263.
GALE WATCH FROM THURSDAY MORNING THROUGH THURSDAY EVENING FOR
LSZ265.
LAKE MICHIGAN...
NONE.
&&
$$
SYNOPSIS...KC
SHORT TERM...KC
LONG TERM...KF
AVIATION...TK
MARINE...KC
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1242 PM EST TUE JAN 17 2012
LATEST UPDATE...AVIATION...
.SYNOPSIS...(943 AM EST TUE JAN 17 2012)
LOW PRESSURE WILL BRING RAIN CHANGING TO FREEZING DRIZZLE AND THEN
SNOW TODAY. FROM 2 TO 6 INCHES OF SNOW IS EXPECTED NORTH OF
INTERSTATE 96 BY MIDNIGHT. THE EVENING COMMUTE COULD BE SLOWED BY
ICY ROADS AS TEMPERATURES DROP BELOW FREEZING THIS AFTERNOON. LAKE
EFFECT SNOW SHOWERS ARE EXPECTED OVERNIGHT AS ARCTIC AIR MOVES IN
WITH 1 TO 4 INCHES OF ADDITIONAL SNOW ALONG AND WEST OF HIGHWAY 131
BY WEDNESDAY MORNING.
&&
.SHORT TERM...(943 AM EST TUE JAN 17 2012)
(THIS AFTERNOON THROUGH THURSDAY AFTERNOON)
DROPPED THE DENSE FOG ADVISORY AS RAIN EARLIER THIS MORNING HAS
ALLOWED VISBYS TO IMPROVE. INCREASING NORTHEAST WINDS SHOULD KEEP
DENSE FOG FROM REFORMING. DROPPED MENTION OF THUNDER AS SOUTHERN
FORECAST AREA IS CURRENTLY DRY SLOTTED AND HRRR RUC SHOWS ANY
CONVECTIVE LOOKING PRECIP FORMING OFF TO THE EAST OF THE SOUTHERN
FORECAST AREA.
WILL HAVE TO CONSIDER EXPANDING THE WINTER WEATHER ADVISORY
SOUTHWARD THIS AFTERNOON AS TEMPS FALL BELOW FREEZING ALLOWING
RESIDUAL MOISTURE TO FREEZE ON ROADS...COMBINED WITH SYNOPTIC SNOWS
AND PERHAPS A PERIOD OF FREEZING RAIN OR DRIZZLE.
REST OF PREVIOUS DISCUSSION FOLLOWS.
THE LOW PRESSURE SYSTEM RESPONSIBLE FOR THIS WILL TRACK FROM NEAR
SBN AT 12Z THIS MORNING TO LAKE ONTARIO BY 00Z THIS EVE. PCPN TYPE
TODAY SHOULD BE ALL SNOW ACROSS OUR NORTHERN COUNTIES WHERE SNOW
ACCUMULATIONS OF 3 TO 6 INCHES ARE ANTICIPATED. ACROSS OUR CENTRAL
COUNTIES WE EXPECT LIGHT RAIN/DRIZZLE TO GRADUALLY TRANSITION TO
SNOW TOWARD MID TO LATE MORNING. 1 TO 3 INCHES OF SNOW IS THE MOST
LIKELY OUTCOME ACROSS THIS AREA... MAYBE LOCALLY 4 INCHES WHERE
P-TYPE TRANSITIONS TO SNOW THE SOONEST.
P-TYPE WILL GRADUALLY TRANSITION FROM RAIN TO SNOW ACROSS OUR
SOUTHERN COUNTIES FROM WNW TO ESE THIS AFTN AS SUGGESTED BY 00Z
GFS/NAM LOW LEVEL THICKNESS TOOLS. ONLY A FEW TENTHS TO AS MUCH AS 2
INCHES OF SNOW WILL FALL ACROSS OUR SOUTHERN COUNTIES THIS AFTN...
WITH LOWEST AMOUNTS OF LESS THAN AN INCH NEAR JXN... WHERE P-TYPE
WON/T CHANGE TO SNOW UNTIL MID TO LATE AFTN.
NW FLOW LES WILL DEVELOP LATE THIS AFTN/EVE AS H8 TEMPS FALL
SIGNIFICANTLY TO -16 TO -18 C BY 06Z WED. A QUICK ADDITIONAL 1 TO 4
INCHES OF LES IS ANTICIPATED FROM 00Z THRU 06Z THIS EVE... MAINLY IN
THE FAVORED NW FLOW SNOW BELT AREAS NEAR TO WEST OF US-131. THE AREA
NEAR TO SW OF A LINE FROM MKG TO AZO WILL BE FAVORED FOR LES THIS
EVE. HOWEVER LOWERING INVERSION HEIGHTS AND SFC RIDGING WILL CAUSE
SNOW SHOWERS TO ALREADY BEGIN TO WIND DOWN SLOWLY AFTER 06Z.
A HIGH PRESSURE RIDGE WILL BRING FAIR WX WEDNESDAY BEFORE SNOW
DEVELOPS WEDNESDAY NIGHT AS THE NEXT LOW PRESSURE SYSTEM AND COLD
FRONT MOVES THROUGH FROM 06Z THRU 12Z THUR. STRONG NW FLOW CAA
THURSDAY MEANS THAT TEMPS AROUND DAYBREAK WILL ONLY BE IN THE UPPER
TEENS TO LOWER 20S... WITH SLOWLY FALLING TEMPS THROUGH THE TEENS
THROUGH THE DAY. WNW LES IS ANTICIPATED THURSDAY AS H8 TEMPS PLUMMET
TO -19 TO -21 C BY 00Z FRI. SEVERAL ADDITIONAL INCHES OF SNOW ARE
ANTICIPATED THURSDAY IN FAVORED WNW FLOW SNOW BELT AREAS NEAR TO
WEST OF US-131.
&&
.LONG TERM...(400 AM EST TUE JAN 17 2012)
(THURSDAY NIGHT THROUGH MONDAY)
THE MAIN CHALLENGE IN THE LONG TERM DEALS WITH THE RISK FOR
ACCUMULATING SNOW FRIDAY.
MODELS ARE NOT IN VERY GOOD AGREEMENT. A WEAK MID LEVEL SHORTWAVE
WILL BE DROPPING SOUTHEASTWARD INTO THE GREAT LAKES REGION FOR
FRIDAY. AT THE SURFACE THE HIGH RES EURO KEEPS THE SURFACE LOW FAR
SOUTH OF MI. THE GFS AND NAM ARE SUPPORTING A TRACK FURTHER NORTH.
THIS MORE NORTHERN TRACK WOULD LEAD TO A BAND OF ACCUMULATING SNOW
IN SOUTHWEST MI. THE AIR IS PLENTY COLD ENOUGH TO SUPPORT LAKE
ENHANCEMENT. WILL BUMP UP POPS TO LIKELY FOR WESTERN PARTS OF MY
FORECAST AREA GIVEN THE POTENTIAL FOR SOME LAKE ENHANCEMENT.
OVERALL THE POTENTIAL FOR AN EXTENDED WARMUP IS DIMINISHING. TRENDS
SHOW THE COLDER AIR HOLDING IN PLACE LONGER. FOR THIS REASON WE
LOWERED TEMPERATURES.
&&
.AVIATION...(1242 PM EST TUE JAN 17 2012)
COLD FRONT HAS MOVES PAST ALL OF THE SITES BUT KJXN...AND SHOULD
MOVE PAST KJXN BY 20Z. WE/LL SEE A CHANGE OVER TO SNOW BY 20Z. VSBYS
WILL REMAIN AOB 1 1/2SM -SHSN FOR SEVERAL HOURS EXCEPT IN THE EAST
WHERE THEY MAY BE CLOSER TO 3SM. MVFR CONDITIONS WILL PREVAIL DURING
THE EVENING AS SOME LAKE EFFECT SNOWS DEVELOP. PCPN WILL DIMINISH
OVERNIGHT.
&&
.MARINE...(400 AM EST TUE JAN 17 2012)
GALE WARNING IN EFFECT TODAY DUE TO STRONG NW WINDS ON THE BACK SIDE
OF THE DEPARTING LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...(400 AM EST TUE JAN 17 2012)
NO ICE JAMS HAVE BEEN REPORTED. POTENTIAL FOR THEM WILL INCREASE
THIS WEEK AS COLDER AIR MOVES IN... PARTICULARLY BY THURSDAY AND
FRIDAY WHEN HIGH TEMPS WILL ONLY REACH THE 15 TO 20 DEGREE MARK.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY CONTINUES IN EFFECT UNTIL 7 PM EST THIS
EVENING FOR MASON LAKE OSCEOLA CLARE OCEANA NEWAYGO MECOSTA
ISABELLA MONTCALM AND GRATIOT COUNTIES.
LM...GALE WARNING ST JOSEPH TO MANISTEE 7 AM TO 11 PM TODAY.
&&
$$
SYNOPSIS: OSTUNO
SHORT TERM: LAURENS/OSTUNO
LONG TERM: MJS
AVIATION: 93
MARINE: LAURENS
HYDROLOGY: LAURENS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
943 AM EST TUE JAN 17 2012
LATEST UPDATE...SYNOPSIS/SHORT TERM...
.SYNOPSIS...(943 AM EST TUE JAN 17 2012)
LOW PRESSURE WILL BRING RAIN CHANGING TO FREEZING DRIZZLE AND THEN
SNOW TODAY. FROM 2 TO 6 INCHES OF SNOW IS EXPECTED NORTH OF
INTERSTATE 96 BY MIDNIGHT. THE EVENING COMMUTE COULD BE SLOWED BY
ICY ROADS AS TEMPERATURES DROP BELOW FREEZING THIS AFTERNOON. LAKE
EFFECT SNOW SHOWERS ARE EXPECTED OVERNIGHT AS ARCTIC AIR MOVES IN
WITH 1 TO 4 INCHES OF ADDITIONAL SNOW ALONG AND WEST OF HIGHWAY 131
BY WEDNESDAY MORNING.
&&
.SHORT TERM...(943 AM EST TUE JAN 17 2012)
(THIS AFTERNOON THROUGH THURSDAY AFTERNOON)
DROPPED THE DENSE FOG ADVISORY AS RAIN EARLIER THIS MORNING HAS
ALLOWED VISBYS TO IMPROVE. INCREASING NORTHEAST WINDS SHOULD KEEP
DENSE FOG FROM REFORMING. DROPPED MENTION OF THUNDER AS SOUTHERN
FORECAST AREA IS CURRENTLY DRY SLOTTED AND HRRR RUC SHOWS ANY
CONVECTIVE LOOKING PRECIP FORMING OFF TO THE EAST OF THE SOUTHERN
FORECAST AREA.
WILL HAVE TO CONSIDER EXPANDING THE WINTER WEATHER ADVISORY
SOUTHWARD THIS AFTERNOON AS TEMPS FALL BELOW FREEZING ALLOWING
RESIDUAL MOISTURE TO FREEZE ON ROADS...COMBINED WITH SYNOPTIC SNOWS
AND PERHAPS A PERIOD OF FREEZING RAIN OR DRIZZLE.
REST OF PREVIOUS DISCUSSION FOLLOWS.
THE LOW PRESSURE SYSTEM RESPONSIBLE FOR THIS WILL TRACK FROM NEAR
SBN AT 12Z THIS MORNING TO LAKE ONTARIO BY 00Z THIS EVE. PCPN TYPE
TODAY SHOULD BE ALL SNOW ACROSS OUR NORTHERN COUNTIES WHERE SNOW
ACCUMULATIONS OF 3 TO 6 INCHES ARE ANTICIPATED. ACROSS OUR CENTRAL
COUNTIES WE EXPECT LIGHT RAIN/DRIZZLE TO GRADUALLY TRANSITION TO
SNOW TOWARD MID TO LATE MORNING. 1 TO 3 INCHES OF SNOW IS THE MOST
LIKELY OUTCOME ACROSS THIS AREA... MAYBE LOCALLY 4 INCHES WHERE
P-TYPE TRANSITIONS TO SNOW THE SOONEST.
P-TYPE WILL GRADUALLY TRANSITION FROM RAIN TO SNOW ACROSS OUR
SOUTHERN COUNTIES FROM WNW TO ESE THIS AFTN AS SUGGESTED BY 00Z
GFS/NAM LOW LEVEL THICKNESS TOOLS. ONLY A FEW TENTHS TO AS MUCH AS 2
INCHES OF SNOW WILL FALL ACROSS OUR SOUTHERN COUNTIES THIS AFTN...
WITH LOWEST AMOUNTS OF LESS THAN AN INCH NEAR JXN... WHERE P-TYPE
WON/T CHANGE TO SNOW UNTIL MID TO LATE AFTN.
NW FLOW LES WILL DEVELOP LATE THIS AFTN/EVE AS H8 TEMPS FALL
SIGNIFICANTLY TO -16 TO -18 C BY 06Z WED. A QUICK ADDITIONAL 1 TO 4
INCHES OF LES IS ANTICIPATED FROM 00Z THRU 06Z THIS EVE... MAINLY IN
THE FAVORED NW FLOW SNOW BELT AREAS NEAR TO WEST OF US-131. THE AREA
NEAR TO SW OF A LINE FROM MKG TO AZO WILL BE FAVORED FOR LES THIS
EVE. HOWEVER LOWERING INVERSION HEIGHTS AND SFC RIDGING WILL CAUSE
SNOW SHOWERS TO ALREADY BEGIN TO WIND DOWN SLOWLY AFTER 06Z.
A HIGH PRESSURE RIDGE WILL BRING FAIR WX WEDNESDAY BEFORE SNOW
DEVELOPS WEDNESDAY NIGHT AS THE NEXT LOW PRESSURE SYSTEM AND COLD
FRONT MOVES THROUGH FROM 06Z THRU 12Z THUR. STRONG NW FLOW CAA
THURSDAY MEANS THAT TEMPS AROUND DAYBREAK WILL ONLY BE IN THE UPPER
TEENS TO LOWER 20S... WITH SLOWLY FALLING TEMPS THROUGH THE TEENS
THROUGH THE DAY. WNW LES IS ANTICIPATED THURSDAY AS H8 TEMPS PLUMMET
TO -19 TO -21 C BY 00Z FRI. SEVERAL ADDITIONAL INCHES OF SNOW ARE
ANTICIPATED THURSDAY IN FAVORED WNW FLOW SNOW BELT AREAS NEAR TO
WEST OF US-131.
&&
.LONG TERM...(400 AM EST TUE JAN 17 2012)
(THURSDAY NIGHT THROUGH MONDAY)
THE MAIN CHALLENGE IN THE LONG TERM DEALS WITH THE RISK FOR
ACCUMULATING SNOW FRIDAY.
MODELS ARE NOT IN VERY GOOD AGREEMENT. A WEAK MID LEVEL SHORTWAVE
WILL BE DROPPING SOUTHEASTWARD INTO THE GREAT LAKES REGION FOR
FRIDAY. AT THE SURFACE THE HIGH RES EURO KEEPS THE SURFACE LOW FAR
SOUTH OF MI. THE GFS AND NAM ARE SUPPORTING A TRACK FURTHER NORTH.
THIS MORE NORTHERN TRACK WOULD LEAD TO A BAND OF ACCUMULATING SNOW
IN SOUTHWEST MI. THE AIR IS PLENTY COLD ENOUGH TO SUPPORT LAKE
ENHANCEMENT. WILL BUMP UP POPS TO LIKELY FOR WESTERN PARTS OF MY
FORECAST AREA GIVEN THE POTENTIAL FOR SOME LAKE ENHANCEMENT.
OVERALL THE POTENTIAL FOR AN EXTENDED WARMUP IS DIMINISHING. TRENDS
SHOW THE COLDER AIR HOLDING IN PLACE LONGER. FOR THIS REASON WE
LOWERED TEMPERATURES.
&&
.AVIATION...(700 AM EST TUE JAN 17 2012)
LATEST DATA SUGGESTS A RISK FOR PL AND FREEZING RAIN FOR A FEW SITES
KGRR AND KLAN. KMKG SHOULD SWITCH FROM RAIN TO SNOW BY 15Z. THE
DENSE FOG IS FORECASTED TO GRADUALLY DISSIPATE AS THE COLDER AIR
MOVES IN FROM THE NORTH. CEILINGS AND VISIBILITY VALUES WILL
IMPROVE THE MOST FOR KAZO KJXN AND KBTL THIS MORNING AS UPSTREAM
VALUES IN NRN INDIANA HAVE TRENDED TOWARD IFR.
A BAND OF SNOW SHOULD IMPACT KMKG AND PERHAPS KGRR THE GREATEST LATE
THIS MORNING INTO THE AFTERNOON. LAKE EFFECT WILL DEVELOP LATE THIS
AFTERNOON AND EVENING AS MUCH COLDER AIR FILTERS IN FROM THE
NORTHWEST. THE LAKE EFFECT WILL DIMINISH TONIGHT MAINLY AFTER 06Z.
&&
.MARINE...(400 AM EST TUE JAN 17 2012)
GALE WARNING IN EFFECT TODAY DUE TO STRONG NW WINDS ON THE BACK SIDE
OF THE DEPARTING LOW PRESSURE SYSTEM.
&&
.HYDROLOGY...(400 AM EST TUE JAN 17 2012)
NO ICE JAMS HAVE BEEN REPORTED. POTENTIAL FOR THEM WILL INCREASE
THIS WEEK AS COLDER AIR MOVES IN... PARTICULARLY BY THURSDAY AND
FRIDAY WHEN HIGH TEMPS WILL ONLY REACH THE 15 TO 20 DEGREE MARK.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY CONTINUES IN EFFECT UNTIL 7 PM EST THIS
EVENING FOR MASON LAKE OSCEOLA CLARE OCEANA NEWAYGO MECOSTA
ISABELLA MONTCALM AND GRATIOT COUNTIES.
LM...GALE WARNING ST JOSEPH TO MANISTEE 7 AM TO 11 PM TODAY.
&&
$$
SYNOPSIS: OSTUNO
SHORT TERM: LAURENS/OSTUNO
LONG TERM: MJS
AVIATION: MJS
MARINE: LAURENS
HYDROLOGY: LAURENS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1218 AM EST TUE JAN 17 2012
UPDATED AVIATION DISCUSSION FOR THE 06Z TAFS
.SYNOPSIS... ISSUED AT 433 PM EST
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW GENERAL WRN TROF/
ERN RDG PATTERN ACRS NAMERICA. THERE IS A STRONG DISTURBANCE/120KT
H3 JET MAX IN ONTARIO EMBEDDED WITHIN THE WSW FLOW ALF...AND
ATTENDANT COLD FNT IS PRESSING TOWARD WRN UPR MI EARLY THIS AFTN.
THERE IS QUITE A BIT OF LO CLD IN THE RELATIVELY MILD SSW FLOW AHEAD
OF THIS FNT WITH 12Z GRB RAOB SHOWING THIN SATURATED LYR ARND
H925...BUT MID LVL DRYNESS SHOWN ON THAT RAOB IS PREVENTING ANY
PCPN. TEMPS DROP OFF SHARPLY BEHIND THE APRCHG COLD FNT WITH
READINGS OVER THE MN ARROWHEAD FALLING TOWARD 10F. 12Z INL RAOB
INDICATED A SHARP INVRN NEAR H9 ABV THIS FAIRLY SHALLOW INFUSION OF
COLD AIR...AND THERE IS QUITE A BIT OF LO CLD/SOME -SN IN THAT AREA
AS WELL. FARTHER UPSTREAM...BITTERLY COLD AIR IS PRESENT OVER THE W
HALF OF CANADA...WITH H85 TEMP AS LO AS -32C AT CALGARY. SOME OF
THIS COLD AIR IS SPILLING INTO THE NRN PLAINS...WHERE SFC TEMPS ARE
NOT MUCH ABV ZERO IN NDAKOTA. SEVERAL DISTURBANCES ARE NOTED WITHIN
THE WRN TROF...AND THERE IS A SOMEWHAT ILL DEFINED COMMA CLD NOTED
ON WV IMAGERY PUSHING INTO THE NRN PLAINS. BUT GENERAL DRYNESS IN
THAT AREA INDICATED BY H7 RAOBS HAS LIMITED THE PCPN COVERAGE.
&&
.SHORT TERM /TNGT AND TUE/... ISSUED AT 433 PM EST
MAIN FCST CONCERNS DURING THIS PERIOD REVOLVE ARND SN CHCS/AMOUNTS
AS COLDER AIR MOVES INTO THE UPR LKS AT SAME TIME DISTURBANCE IN THE
NRN ROCKIES MOVES BY JUST TO THE S.
TNGT...DISTURBANCE MARKED BY ILL DEFINED COMMA CLD IN THE NRN PLAINS
IS PROGGED TO MOVE INTO THE NCNTRL PLAINS BY 12Z TUE...WITH SFC LO
NOW TAKING SHAPE IN THE PLAINS DRIFTING NEAR LOWER MI. MEANWHILE...
COLDER AIR TO THE NW WL SLOWLY INFILTRATE THE UPR LKS AS THE LLVL
WIND TURNS MORE TO THE N...DROPPING H85 TEMPS TO ARND -15C OVER WRN
LK SUP TO -10C OVER THE E. WITH OPEN WATER TEMPS ARND 3C...THE
ARRIVAL OF THIS INCOMING AIRMASS WL BE SUFFICIENT TO GENERATE LES W
TO E. ALTHOUGH THE SHARPER FORCING ASSOCIATED WITH THE PLAINS SHRTWV
WL TEND TO BE FOCUSED JUST S OF UPR MI...THE 12Z NAM/GFS SHOW DEEPER
MSTR ARRIVING MAINLY OVER THE NW HALF OF THE CWA OVERNGT WHERE UPR
DVGC/H7-5 FGEN WL BE MAXIMIZED IN RRQ OF 120KT H3 JET MAX MOVING TO
NEAR JAMES BAY. FCST SDNGS SHOW THE ASSOCIATED OMEGA WL BE MAXIMIZED
FAIRLY HI CLOSER TO THESE HIER LVL FORCING MECHANISMS...SO POTENTIAL
FOR TRUE LK ENHANCEMENT IS PROBABLY MINIMAL. WITH GREATER OVERWATER
INSTABILITY AND SHARPER LLVL CNVGC OVER THE FAR W NEAR IWD PER NAM
FCST...EXPECT HEAVIER SHSN THERE IN THE PRESENCE OF FVRBL UPSLOPE N
WIND. ALTHOUGH THE LLVL FGEN WL BE SHARPER OVER THE SE ZNS CLOSER TO
THE SFC LO/FNT TO THE SE... THE AIRMASS APPEARS WL BE TOO DRY
OVERALL FOR ANY SGNFT PCPN THERE THRU 12Z.
TUE...UPR DISTURBANCE/SFC LO TO THE S WL SHIFT TO THE E...WITH
TRAILING SFC HI PRES FCST TO SHIFT TOWARD WRN MN BY LATE IN THE DAY.
DEEP MSTR ASSOCIATED MAINLY WITH HI LVL FORCING RELATED TO COUPLED
UPR DVGC IN RRQ OF UPR JET TO THE NE/LEFT EXIT OF JET SUPPORTING
SHRTWV IN THE LOWER LKS AND H7-5 FGEN WL EXIT W-E IN THE AFTN. BEST
CHC FOR WDSPRD PCPN WL BE INTO MID AFTN...WHEN MODELS SHOW SHARPER
UPR DVGC AND LINGERING FGEN TENDING TO EXIT TO THE E. ALTHOUGH PURE
LES WL LINGER EVEN AFT THE EXIT OF THE DYNAMICS AS H85 TEMPS TUMBLE
TOWARD -20C WITH INFLUX OF ARCTIC AIR TO THE NW...STEADILY BACKING
WINDS IN THE AFTN WL TEND TO LIMIT LES BAND RESIDENCE TIME AND
ACCUMS. AWAY FM LK MOISTENING...PLAN ON NO MORE THAN 1 TO 2 INCHES
OF SN WITH BETTER OMEGA ABV THE DGZ AND H85 CAD TENDING TO OFFSET
THE UPR DVGC/FGEN. EXPECT LTL DIURNAL RISE OF TEMP AS BITTERLY COLD
AIRMASS IN THE NRN PLAINS FOLLOWS INTO THE UPR LKS.
AS FOR HEADLINES...RETAINED GOING ADVY FOR GOGEBIC/ONTONAGON ZNS
WITH MOST FAVORABLE OVERWATER INSTABILITY/FETCH/UPSLOPE WIND
COMPONENT. OPTED TO ISSUE AN ADVY FOR BARAGA/MQT AS WELL FOR THE
09Z-21Z TIME WITH THE SAME FAVORABLE PARAMETERS. WITH WSHFT TO THE
NW ON TUE AFTN...THE HEAVIER SHSN SHOULD END IN THIS AREA EVEN
EARLIER THAN OVER THE W. COORDINATED WITH DLH ON HEADLINES FOR IWD
AREA.
.LONG TERM /TUESDAY NIGHT THROUGH MONDAY/...
TUESDAY NIGHT...
THE 500MB THROUGH CURRENTLY SET UP ACROSS MT THROUGH NV AND S CA
WILL BE DIRECTLY OVERHEAD AT 00Z WEDNESDAY...WITH THE MAIN LOW
SLOWLY SWINGING ACROSS CENTRAL TO NE CANADA. THE SFC LOW /FARTHER
EAST/ SHOULD BE JUST NORTH OF LAKE ONTARIO AT 00Z WEDNESDAY...WITH A
TROUGH EXTENDING THROUGH UPPER MICHIGAN INTO FAR WESTERN LAKE
SUPERIOR. N-NW WINDS WILL PREVAIL INITIALLY WITH 850MB TEMPS
AVERAGING -18C.
WEDNESDAY INTO THURSDAY...
BY 12Z WEDNESDAY THE TROUGH WILL RESIDE ACROSS EASTERN
UPPER MI...BEFORE BEING QUICKLY PUSHED EASTWARD BY MID MORNING
THANKS TO THE STRONG SFC RIDGE TO OUR SOUTH...AND ANOTHER LOW
NEARING FROM THE DAKOTAS. THE RESULT WILL BE WINDS BECOMING WESTERLY
AND SOUTHWESTERLY THROUGH THE DAY...WITH LES HOLDING ON THE LONGEST
ACROSS THE KEWEENAW PENINSULA AND FAR EAST NEAR LAKE SUPERIOR /INTO
THE MID MORNING HOURS/.
A WEAK RIDGE TO ZONAL FLOW CAN BE EXPECTED ALOFT WEDNESDAY...BEFORE
THE NEXT TROUGH SWINGS IN FROM MN WEDNESDAY NIGHT INTO THURSDAY
MORNING /ASSOCIATED WITH THE SFC LOW/. EXPECT THE SFC LOW TO PUSH
OVER THE WESTERN THIRD OF THE CWA BY 00Z...CENTRAL BY 06Z...AND
RESIDE JUST TO OUR EAST BY 12Z THURSDAY. THE 06Z RUN OF THE GFS IS
THE WEAKEST AND FARTHEST SOUTH WITH THIS FEATURE /APPROX 220 MILES
SSE OF THE ECMWF/. THIS MAKES TIMING THE ONSET OF PRECIPITATION
DIFFICULT...WITH THE ECMWF INDICATING A SHORT DRY PERIOD FOR MUCH OF
THE AREA WEDNESDAY AFTERNOON...WHILE THE KEWEENAW STAYS IN THE SNOW
IF THE GFS IS TO BE BELIEVED. AT THIS POINT...THE GFS LOOKS TO BE AN
OUTLIER...WITH LIMITED INPUT INTO THIS FORECAST FROM WEDNESDAY ON.
THE 12Z GFS HAS MOVED CLOSE TO THE CONSENSUS...SPLITTING THE
ORIGINAL 220 MILE DIFFERENCE IN HALF. ANY OF THE SOLUTIONS WOULD
BRING A CHANCE OF LES ON SOUTHERLY WINDS TO THE EASTERN CWA LATE
WEDNESDAY AFTERNOON INTO THE EVENING HOURS...BEFORE THEY BECOME TOO
MUCH OUT OF A SW OR W DIRECTION /850MB TEMPS OF -11 TO -14C SHOULD
BE COLD ENOUGH/.
THE MAIN 500MB LOW WILL REMAIN WELL TO OUR NORTH...SLOWLY
RETROGRADING WESTWARD FROM THE HUDSON BAY AREA TO AK BY THE END OF
THE WORK WEEK. A SIGNIFICANT TROUGH WILL STILL LINGER ACROSS N
HUDSON BAY FOR THE FORESEEABLE FUTURE.
THE COLDEST AIR SEEN IN SOME TIME WILL SLIDE IN THURSDAY...DROPPING
TO -24C BY THE AFTERNOON HOURS ON GUSTY NW WINDS...WITH LIKELY SNOW
SHOWERS RETURNING TO THE AREA NEAR LAKE SUPERIOR. THIS WILL BE THE
CASE UNTIL WAA SW WINDS TAKE HOLD AGAIN FRIDAY MORNING. WILL KEEP
THIS SYSTEM MENTIONED IN THE HWO...AND CONTINUE TO MONITOR IT
CLOSELY FOR THE POTENTIAL FOR HEADLINES AS IT MOVES CLOSER.
FRIDAY THROUGH MONDAY...
FCST MODELS BEGIN TO DIVERGE IN THE OVERALL PATTERN LATE
FRIDAY...WITH THE ECMWF AND CANADIAN KEEPING A TROUGH OVERHEAD WITH
THE GFS INDICATES MORE IN THE WAY OF SW FLOW. THESE DIFFERENCES
CONTINUE AND BECOME MORE DRAMATIC TROUGH MONDAY. THIS IS SEEN ON THE
SFC CHARTS AS WELL AT 00Z SUNDAY WITH THE LOCATION OF THE NEXT LOW
VARYING SOME 1K MILES BASED ON THE 16/06Z GFS AND 16/00Z ECMWF. THE
GFS HAS IT JUST NW OF LAKE SUPERIOR...WHILE THE ECMWF IS STILL
ORGANIZING THE FEATURE OVER SOUTHERN ALBERTA. GIVEN ALL THE
DIFFERENCES...WILL NOT DEVIATE MUCH FROM AN AVERAGE/BLENDED SOLUTION.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
UNDER COOLING AIRMASS...MVFR CONDITIONS AT KIWD/KCMX/KSAW WILL
TRANSITION TO IFR FROM W TO E OVERNIGHT THRU THE MORNING AS LAKE
EFFECT SNOW SHOWERS DEVELOP...AIDED BY DEEPER MOISTURE ASSOCIATED
WITH INCOMING UPPER LEVEL DISTURBANCE. BEST CHC FOR LIFR SHOULD
OCCUR LATE IN THE NIGHT THRU THE MORNING AT KIWD WHERE OVERWATER
INSTABILITY WILL BE MAXIMIZED IN THE PRESENCE OF
FAVORABLE/CONVERGENT UPSLOPE N WIND. SOME PERIODS OF LIFR NOT OUT OF
THE QUESTION AT KSAW MID TO LATE MORNING AS WELL UNDER FAVORABLE
UPSLOPE. IMPROVEMENT SHOULD OCCUR AT ALL TERMINALS MID TO LATE AFTN
AS DEEPER MOISTURE DEPARTS AND LOW-LEVEL CONVERGENCE BEGINS TO
WEAKEN. CONTINUED BACKING OF WINDS IN THE EVENING SHOULD BRING AN
END TO -SHSN AT KIWD WITH ONLY SOME FLURRIES LINGERING AT KSAW.
OVERLAKE TRAJECTORY WILL MAINTAIN -SHSN/MVFR CONDITIONS AT KCMX THRU
THE EVENING HRS.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
EXPECT N WINDS UP TO 30 KTS/SOME FREEZING SPRAY ON TUE WITH INFLUX
OF COLDER AIR IN THE WAKE OF LO PRES SHIFTING E THRU THE LOWER LKS.
WINDS WL DIMINISH AND BACK TO THE SW TUE NGT THRU WED WITH THE
PASSAGE OF A RIDGE AXIS AND AHEAD OF ANOTHER LO PRES SYSTEM. A
BITTERLY COLD AIRMASS WILL FOLLOW THIS LO AS NW WINDS INCREASE TO
AOA GALE INTENSITY /MAINLY THURSDAY/. HEAVY FREEZING SPRAY WILL BE A
GOOD BET OVER MOST OF THE LAKE /MAINLY WEDNESDAY NIGHT INTO THURSDAY
WEST/ BEFORE WINDS DIMINISH AGAIN BY LATE IN THE WEEK WITH THE
APPROACH OF ANOTHER HI PRES RDG.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY FROM 4 AM TO 5 PM EST TUESDAY FOR
MIZ004-005.
LAKE EFFECT SNOW ADVISORY FROM 1 AM EST /MIDNIGHT CST/ TO
7 PM EST /6 PM CST/ TUESDAY FOR MIZ002-009.
LAKE SUPERIOR...NONE.
LAKE MICHIGAN...NONE.
&&
$$
SYNOPSIS...KC
SHORT TERM...KC
LONG TERM...KF
AVIATION...ROLFSON
MARINE...KC
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1158 PM EST MON JAN 16 2012
LATEST UPDATE...AVIATION...
.SYNOPSIS...(400 PM EST MON JAN 16 2012)
LOW PRESSURE WILL TRACK FROM MISSOURI TO LAKE ONTARIO TONIGHT AND
TUESDAY. THIS SYSTEM WILL PRODUCE A WIDESPREAD 3 TO 6 INCH SNOWFALL
OVER NORTHERN LOWER MICHIGAN... AND A WINTRY MIX OF SNOW AND
FREEZING RAIN ACROSS CENTRAL LOWER MICHIGAN.
MEANWHILE RAIN AND AREAS OF FOG WILL IMPACT SOUTHERN LOWER MICHIGAN
TONIGHT. THE RAIN WILL CHANGE TO SNOW SHOWERS TUESDAY AFTERNOON ONCE
THE LOW PASSES BY AND COLDER AIR RUSHES IN. LAKE EFFECT SNOW SHOWERS
TUESDAY NIGHT COULD PRODUCE 1 TO 3 INCHES OF ADDITIONAL SNOW ALONG
AND WEST OF HIGHWAY 131.
MORE SNOW SHOWERS...WITH SOME ACCUMULATIONS...ARE ANTICIPATED
WEDNESDAY NIGHT AND THURSDAY AS THE NEXT COLD FRONT PUSHES THROUGH
THE REGION AND BRINGS A REINFORCING SHOT OF COLD ARCTIC AIR.
&&
.SHORT TERM...(930 PM EST MON JAN 16 2012)
(TONIGHT THROUGH WEDNESDAY AFTERNOON)
A DENSE FOG ADVISORY IS BEING ISSUED FOR THE OVERNIGHT PERIOD
THROUGH MID MORNING TUESDAY FOR ROUGHLY THE SOUTHERN HALF OF OUR
FCST AREA. A COUPLE OF OBS SITES ARE REPORTING VSBY DOWN TO A
QUARTER MILE AND MOST OTHER OBS SITES ACROSS OUR SOUTHERN FCST AREA
ARE SHOWING A SLOW BUT STEADY TREND DOWNWARD WITH VISBYS. SHORT
RANGE GUIDANCE SUCH AS THE 13KM RUC SUGGESTS FOG WILL ONLY BECOME
MORE DENSE/WIDESPREAD OVERNIGHT AND THIS MAKES PHYSICAL SENSE GIVEN
HIGH BOUNDARY LAYER MOISTURE AND TEMPS RIGHT AT OR NEAR THE DEW PT.
REMAINDER OF PREVIOUS SHORT TERM FCST DISCUSSION FOLLOWS...HAVE
ISSUED A WINTER WEATHER ADVISORY FOR THE NRN CWFA FOR LATE
TONIGHT AND TUESDAY FOR A MIXTURE OF SNOW AND FREEZING RAIN CHANGING
TO ALL SNOW. AM THINKING 3-5 INCHES OF SYNOPTIC SNOWS NORTH OF A
LINE FROM ROUGHLY HART TO CLARE WHERE PCPN WILL BE MOSTLY SNOW. JUST
SOUTH OF THERE.... INCLUDING BIG RAPIDS... MT PLEASANT AND ALMA...
WILL FCST 1 TO 3 INCHES OF SNOW WITH UP TO A TENTH OF AN INCH OF
FREEZING RAIN.
MODELS INSIST THAT LIGHT RAIN/DRIZZLE WILL RAPIDLY DEVELOP EARLY
THIS EVENING IN RESPONSE TO TIGHTENING FRONTAL ZONE OVERHEAD AND
APPROACHING SHORTWAVE. FORTUNATELY TEMPERATURES HAVE WARMED ABOVE 40
IN MOST AREAS AND FREEZING RAIN WILL NOT BE A THREAT TO START OUT.
HOWEVER LATER THIS EVENING THE FAR NRN CWFA MAY COOL BACK DOWN TO
NEAR FREEZING...WITH A MUCH BETTER RISK OF FALLING BELOW FREEZING
VERY LATE TONIGHT AS THE LOW LEVEL NE FLOW DEVELOPS/STRENGTHENS ON
THE NORTH SIDE OF THE STRENGTHENING FRONTAL ZONE.
THE BULK OF THE EVENT OCCURS ON TUESDAY WHEN THE DEFORMATION ZONE
IMPACTS THE REGION. PRIOR TO THAT THE MOISTURE IS RATHER SHALLOW AND
THE DGZ IS NOT SATURATED. BEST OMEGA/DGZ COMBINATION SETS UP ACROSS
THE NW CWFA AROUND LDM. MEANWHILE BECAUSE OF THE SFC LOW TRACK...
PROGS SHOW COLD AIR TAKING IT/S TIME ARRIVING IN THE SE CWFA AROUND
JXN ON TUESDAY. IT TAKES UNTIL AFTER 18Z-21Z TO COOL SUFFICIENTLY TO
SUPPORT SNOW. THUS WILL FCST UNDER AN INCH OF ACCUMS FROM LAN SOUTH.
THE LAKE EFFECT ON TUESDAY NIGHT LOOKS FAIRLY SHORT LIVED AS SURFACE
RIDGING AND LOWERING INVERSION HEIGHTS ARRIVE AFTER 06Z. HOWEVER
SOME QUICK ADDITIONAL 1-4 INCH ACCUMULATIONS ARE CERTAINLY POSSIBLE
ALONG/WEST OF HWY 131 PRIOR TO THE LATE NIGHT DIMINISHING TREND.
WEDNESDAY LOOKS QUIET AS SHORTWAVE RIDGING IMPACTS THE REGION IN
BETWEEN SYSTEMS.
&&
.LONG TERM...(400 PM EST MON JAN 16 2012)
(WEDNESDAY NIGHT THROUGH MONDAY)
A CLIPPER IS GOING TO BRING ANOTHER SHOT OF ARCTIC AIR TO THE
REGION. LIKE PREVIOUS COLD AIR INTRUSIONS...THIS ONE WON/T LAST LONG
EITHER...A COUPLE OF DAYS. SHORT RANGE MODELS SHOW THE COLD FRONT
MOVING ACROSS THE CWA WEDNESDAY NIGHT. WE/LL SEE SHSN DEVELOP ALONG
AND BEHIND THE COLD FRONT. WE HAVE LIKELY POPS OVER THE WRN CWA WED
NIGHT AND THURSDAY. WE SHOULD SEE SEVERAL INCHES OF ACCUMULATIONS IN
THE USUAL NW SNOW BELT AREAS AS H8 -20C AIR MOVES ACROSS THE LAKE.
INVERSION HEIGHTS FALL DURING THE DAY AND NIGHT BEFORE SW FLOW WAA
FRIDAY BRINGS IN SOME MORE MOISTURE. WSW FLOW LAKE ENHANCED FLOW
WILL MEAN ACCUMULATING SNOW POSSIBLE AGAIN FRIDAY. H8 TEMPS WARM
ENOUGH FRIDAY NIGHT/SATURDAY SUCH THAT LAKE EFFECT SNOW SHOULD STOP.
WAA CONTINUES INTO SUNDAY WHERE TEMPS SHOULD CLIMB ABOVE 40 AGAIN
AHEAD OF THE NEXT CLIPPER SUNDAY NIGHT. MIXED RAIN/SNOW SUNDAY INTO
MONDAY AS THE CLIPPER AND TRAILING COLD FRONT MOVE THROUGH. THERE
DOESN/T APPEAR TO BE A STRONG SURGE OF ARCTIC AIR BEHIND THE SUNDAY
CLIPPER.
&&
.AVIATION...(1158 PM EST MON JAN 16 2012)
THE DENSE FOG AND DRIZZLE HAVE BECOME RATHER EXTENSIVE ALONG THE
I-96 TAF SITES AND WILL SOON SPREAD TO THE I-94 SITES AS THE LOW
PRESSURE SYSTEM GETS CLOSER TO THE AREA (LIGHTER WINDS). THE DENSE
FOG WILL PREVAIL UNTIL THE CENTER OF THE SURFACE LOW PASSES EAST OF
THE TAF SITES... AROUND 15Z OR SO. SOME RAIN IS EXPECTED OVERNIGHT
BUT AT THIS POINT FREEZING RAIN OR DRIZZLE SEEM UNLIKELY AT ANY OF
THE TAF SITES.
ONCE THE SURFACE LOW IS EAST OF THE AREA... SAY AROUND 15Z... THE
COLD AIR WILL BE PULLED IN FROM THE NORTH AND TURN THE RAIN TO SNOW.
SOME FREEZING RAIN IS POSSIBLE ALONG THE I-96 TAF SITES. ALL SNOW IS
EXPECTED THROUGH THE AFTERNOON AT THOSE SITES. THE I-94 TAFS WILL
SEE SNOW BY MID AFTERNOON.
&&
.MARINE...(400 PM EST MON JAN 16 2012)
WILL LET THE SMALL CRAFT ADVISORY EXPIRE AT 4 PM... BUT ISSUE A
GALE WARNING FOR TUESDAY DUE TO STRONG NW FLOW ON THE BACK SIDE OF
THE DEPARTING SYSTEM.
&&
.HYDROLOGY...(400 PM EST MON JAN 16 2012)
NO ICE JAMS HAVE BEEN REPORTED... BUT WILL MONITOR.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...DENSE FOG ADVISORY UNTIL 11 AM TUESDAY FOR MUSKEGON...
OTTAWA... KENT... IONIA... CLINTON... ALLEGAN... BARRY...
EATON... INGHAM... VAN BUREN... KALAMAZOO... CALHOUN
AND JACKSON COUNTIES.
WINTER WEATHER ADVISORY FROM 10 PM THIS EVENING TO 7 PM EST
TUESDAY FOR MASON LAKE OSCEOLA CLARE OCEANA NEWAYGO MECOSTA
ISABELLA MONTCALM AND GRATIOT COUNTIES.
LM...GALE WARNING ST JOSEPH TO MANISTEE TUESDAY INTO TUESDAY
EVENING... 7 AM TO 11 PM.
&&
$$
SYNOPSIS: MEADE
SHORT TERM: MEADE/LAURENS
LONG TERM: 93
AVIATION: WDM
MARINE: MEADE
HYDROLOGY: MEADE
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON MS
726 PM CST WED JAN 18 2012
.UPDATE...DRY AIR MASS RADIATING OUT A BIT FASTER THAN HOURLY CURVES
WHICH HAVE BEEN STEEPENED A BIT AND THEN FLATTENED LATER IN THE
NIGHT. LATEST RUC PLACE 1023MB RIDGE NOW ALONG MS RIVER OVER SWRN AL
BY 09Z WITH RETURN SLY FLOW PROBABLY AFFECTING LOCATIONS NEAR AND W
OF MS RIVER BEFORE DAYBREAK. HAVE BUMPED READINGS DOWNWARD SLIGHTLY E
OF THE MS RIVER CLOSER TO THE AFTERNOON MINIMUM DEWPOINTS. IN ADDITION
DECENT CIRROSTRATUS SHIELD DROPPING ACROSS OUR NRN HALF OF THE CWFA
FROM THE NW AS SHARP 300MB TROUGH SWEEPING THROUGH TN VALLEY REGION
WITH HELP FROM 180KT JET CORE DIVING DOWN THE MO RIVER VALLEY.
PER PREVIOUS DISCUSSION...HAVE GONE AHEAD AND ADDED PATCHY FOG TO
GRIDS FOR CENTRAL AND SRN MS LATE THURSDAY NIGHT AS SHALLOW MOIST
ADVECTION SETUP LOOKS GOOD./40/
&&
.AVIATION...VFR HIGH LEVEL CIRRUS AND LIGHT NNE SURFACE FLOW WILL
CONTINUE THROUGH LATE TONIGHT. AS SURFACE HIGH SLIPS EAST AND
REBUILDS...LOW LEVEL FLOW WILL QUICKLY COME AROUND TO S/SW AND
STRENGTHEN THURSDAY MORNING. SLY WINDS WILL BECOME GUSTY BY LATE THU
MORNING PARTICULARLY IN THE DELTA AS 925 MB FLOW STRENGTHENS TO 40
KT. ANY SIGNIFICANT LOW LEVEL MOISTURE RETURN APPEARS DELAYED UNTIL
ABOUT 8PM-MIDNIGHT THURSDAY NIGHT WHEN MVFR STRATUS/FOG COULD SPREAD
FROM S TO N. AREAS OF AT LEAST MVFR LIKELY FOR FRIDAY MORNING./40/
&&
.PREV DISCUSSION... /ISSUED 314 PM CST WED JAN 18 2012/
SHORT TERM...AN INCREASINGLY CHALLENGING FORECAST FROM THURSDAY
NIGHT INTO THE LONG TERM PERIOD. THURSDAY S/SW LOW LEVEL FLOW KICKS
UP IN EARNEST AS 925 MB FLOW INCREASES TO 40 KT. MOISTURE RETURN WILL
LAG SOMEWHAT...BUT BY AFTERNOON SHOULD BEGIN TO SEE SOME INCREASE IN
LOWER/MID CLOUDS. TEMPERATURES WILL RESPOND TO WARM AIR ADVECTION
WITH MAXES IN THE 60S EXPECTED. BY THURSDAY NIGHT LOW LEVEL MOISTURE
RETURN IS IN FULL GEAR AND EXPECT WIDESPREAD ADVECTION STRATUS AND
FOG TO DEVELOP. SREF SHOWING DECENT PROBS FOR VSBYS LESS THAN 1 MILE
OVER S/W AREAS SO WILL HAVE TO MONITOR STRENGTH OF LOW LEVEL
FLOW/MIXING TO SEE IF DENSE ADVECTION FOG WILL DEVELOP.
STRATUS HANGS AROUND MUCH OF FRIDAY ALONG WITH A SLIGHT CHANCE OF
SHOWERS IN MOIST ADVECTION PATTERN...WENT A BIT ABOVE GFS MOS POPS.
THINGS THEN BEGIN TO GET INTERESTING FOR FRIDAY NIGHT/SATURDAY.
MODELS HAVE BEEN HAVING A VERY DIFFICULT TIME HANDLING AMPLIFYING
SHORT WAVE FORECAST TO APPROACH AREA BY SAT WITH LITTLE RUN TO RUN
CONSISTENCY. 12Z GFS AND EC ARE IN A LITTLE BETTER AGREEMENT WITH
SHOWING A DEEPENING UPPER SYSTEM WITH SURFACE LOW PASSING N OF AREA
AND FRONT SAGGING INTO REGION. HOWEVER GFS IS FASTER WITH SURFACE
FEATURES WHILE EC IS FASTER WITH UPPER SYSTEM. FOR NOW TRIED TO USE A
BLEND OF THE MODELS AS FAR AS PROGRESSION OF MASS FIELDS. AS FAR AS
DETAILS...MODELS AGREE ON RAIDLY INCREASING LOW LEVEL MOISTURE UNDER
MID LEVEL COLD TEMPERATURES...500 MB TEMPS AROUND -15C AND 300 MB
TEMPS AROUND -45C...AND MODERATE LAPSE RATES. THIS RESULTS IN
INCREASING INSTABILITY OVERNIGHT FRIDAY NIGHT WITH MLCAPE VALUES
NEARING 1000 J/KG. UPPER JET BECOMES QUITE FAVORABLE OVER NORTHERN
AREAS LATER FRIDAY NIGHT AS REGION GETS INTO LEFT EXIT REGION OF
SOUTHERN BRANCH AND RIGHT ENTRANCE REGION OF NORTHERN BRANCH. GFS IS
MORE BULLISH THAN EC IN BREAKING OUT CONVECTION...BUT MODELS
GENERALLY AGREE ON A DECENT RISK OF STORM ACTIVITY N OF I-20 LATER
FRIDAY NIGHT. GIVEN FAVORABLE SHEAR AND INSTABILITY AM GROWING MORE
CONCERNED ABOUT SEVERE WEATHER RISK DURING THIS PERIOD ACROSS
NORTHERN PART OF FORECAST AREA...AND HAVE ADDED A MENTION TO THE HWO
FOR FRIDAY NIGHT.
SATURDAY IS EVEN MORE OF A CHALLENGE AS ECMWF PULLS UPPER
FORCING OFF TO THE EAST CAUSING COLD FRONT TO BE MAIN FORCING FOR
CONVECTION...WHILE GFS HAS GOOD UPPER SUPPORT AND MUCH MORE
WIDESPREAD PRECIPITATION. FOR NOW HAVE BACKED OFF HIGHER POPS OF
GFS AND WENT MORE TORWARD AN IDEA OF SCATTERED STORMS. STILL WILL BE
A RISK OF SEVERE ACTIVITY WITH ANY STORMS GIVEN GOOD INSTABILITY/
SHEAR COMBO...PARTICULARLY CONSIDERING THIS IS JANUARY. GFS SCENARIO
WOULD RESULT IN A MORE ROBUST THREAT...BUT EVEN EC SCENARIO WITH
STRONG LOW LEVEL BOUNDARY FORCING CONVECTION WOULD RESULT IN AN
ISOLATED SEVERE THREAT. AS FAR AS TEMPERATURES FRIDAY NIGHT/SATURDAY
THIS WILL BE A BIG CHALLENGE...ESPECIALLY SATURDAY...AS FAR AS
POSITIONING OF RELATIVELY STRONG LOW LEVEL BOUNDARY. FOR NOW WENT
NEAR GFS MAXES...BUT IF GFS IS RIGHT WITH PUSHING FRONT THROUGH MORE
AGGRESSIVELY WOULD BE LOOKING AT FALLING TEMPS FROM N TO S AS
BOUNDARY PUSHES THROUGH THE AREA.
LONG TERM...
ACTIVE BUT VERY CHALLENGING...LOW CONFIDENCE...FORECAST SITUATION FOR
SUNDAY THROUGH WEDNESDAY. NOT MUCH MODEL AGREEMENT ON HOW VERY FAST
FLOW WILL TRANSITION TO A MORE AMPLIFIED PATTERN...WITH LITTLE RUN TO
RUN CONTINUITY WITH MODELS. FOR NOW EXPECT CHANGEABLE AND UNSETTLED
WEATHER PATTERN THROUGH THE PERIOD. PREVIOUS APPLICABLE SECTION OF
LONG TERM DISCISSION FOLLOWS...
I WISH I COULD SAY CONFIDENCE IN THE FORECAST INCREASES GOING INTO
NEXT WEEK BUT IT DOESNT AS SPREAD IN MODEL SOLUTIONS REMAINS
UNSETTLINGLY LARGE. IT APPEARS ANOTHER FRONTAL PASSAGE WILL OCCUR
SOMETIME BETWEEN EARLY MON AND EARLY TUE. HIGH PRESSURE WILL SHIFT
QUICKLY ACROSS THE REGION IN WAKE OF THAT FRONT FOLLOWED BY
INCREASING RAIN CHANCES SOMETIME MID WEEK. LAST NIGHT I MENTIONED
THAT THE GFS WAS SHOWING SOME POTENTIAL IN A SEVERE WEATHER EVENT FOR
MON/TUE...NOW IT IS THE ECMWF SHOWING SOME POTENTIAL AROUND MID WEEK
WITH THE GFS HINTING AT SOME KIND OF SEVERE WEATHER SIGNAL A BIT
LATER. UNCERTAINTY IS HIGH...BUT THE MODELS CONTINUE TO HINT AT SOME
KIND OF SEVERE WEATHER SIGNAL NEXT WEEK. STAY TUNED AS WE HEAD INTO
THE WEEKEND.
AS FOR THE FORECAST ELEMENTS...DIDNT SWAY TOO FAR FROM THE GFS MOS
THROUGH THE WEEKEND ALTHOUGH A I DID RAISE THE COLD MEX GUIDANCE SAT
NIGHT GIVEN THE AFOREMENTIONED HIGH SPREAD IN THE MOS SUITE. HEADED
INTO NEXT WEEK I GENERALLY USED THE HIGH ENSEMBLE NUMBERS AS MORE
CONFIDENCE WAS PLACED IN THE WARMER/MORE PROGRESSIVE ECMWF
MODEL...BUT AGAIN CONFIDENCE IS LOW. /AEG/BK/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 30 65 50 72 / 0 7 14 14
MERIDIAN 26 63 48 70 / 0 6 12 14
VICKSBURG 33 66 49 74 / 0 7 14 13
HATTIESBURG 30 68 54 77 / 0 13 16 16
NATCHEZ 33 66 54 74 / 0 12 16 13
GREENVILLE 30 60 46 69 / 0 4 6 13
GREENWOOD 29 61 45 67 / 0 4 6 13
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
318 AM CST Tue Jan 17 2012
.DISCUSSION...
Two waves of precipitation ongoing this morning as an upper level
trough moves across the region. The first across portions of central
into Eastern Missouri in the form of showers and strong to severe
thunderstorms and the other across southern Iowa, southeast Nebraska
and northern Missouri. This second area has been a mix of snow
freezing rain and sleet through the overnight hours. Short term
guidance and ongoing trends suggests this activity to have moved out
of most of the forecast area by 12z. Will maintain a small area of
light snow or flurries across far north-central to northeast
Missouri through 15z for any lingering precipitation.
Deep isentropic downglide should erode the residual cloud cover
through this morning with most of the area clearing by later this
afternoon. Otherwise, strong CAA ongoing this morning with the
freezing line virtually bisecting the forecast area at the moment.
This trend will persist through the day as brisk and gusty northwest
low level flow is expected to continue as sfc ridge settles into the
plains. Looking at upstream temperatures and the expected CAA regime
through the day, expect most if not all areas will remain near or
below freezing today.
Canadian air mass will fully settle across the area tonight as the
aforementioned sfc ridge continues southeast. Light winds and clear
skies will result in efficient radiational cooling tonight allowing
temperatures to fall into the teens and single digits.
The cold spell will be fairly short lived as the sfc ridge quickly
slides east and southerly low level flow returns by Wednesday
morning. The next upper level trough will slide across the northern
tier of the country Wednesday with accompanying sfc low moving into
the Great Lakes by Wednesday evening. In response, brisk
southwesterly low level flow will advect warmer temperatures into
the area by Wednesday afternoon with near to slightly above average
readings expected.
Yet another cold front will move through the area Wednesday night
into Thursday morning continuing the temperature roller coaster.
Weak, elongated vorticity on the southern flank of the upper level
system will traverse the northern portions of the forecast area late
Wednesday night. This may provide sufficient ascent to produce some
scattered flurries, mainly across far northern Missouri.
Deroche
Medium range (Friday through Monday)...
Zonal flow will be set up across the CONUS come Friday. Models
advertise a weak upper level shortwave moving from the Northern
Plains into the Upper Midwest. Moisture content available for this
system will be meager as it moves through. A frontal boundary
extending from the Tennessee River Valley through the Deep South will
keep Gulf moisture pinned south and east of the forecast area. There
may be enough weak mid and upper level forcing to allow for a slight
chance of light showers across the eastern half of the CWA. High
pressure will move into the area Friday night with cold overnight
lows in the mid teens to mid 20s before a warming trend. The surface
high will slide off to the east on Saturday bringing a return of warm
southerly flow to the area as weak upper level ridging builds into
the region. High temperatures by Sunday will range from the upper 40s
to upper 50s. By Monday, zonal flow begins to break down across the
CONUS as a upper level trough moves into the west coast. Models
differ on the track, timing, and strength of this next system as the
GFS is much faster in bringing an open wave through the Rockies and
into the Plains on Monday. This faster and weaker solution will bring
rain showers to the area on Monday. The slower EC brings the trough
into the west coast and then digs it southward into the Southern
Rockies cutting off an upper low across the Four Corners region by
Monday night, delaying the onset of precipitation. To account for the
faster GFS have added chance pops to the forecast on Monday.
73
&&
.AVIATION...
Thunderstorms remain well south of terminals and mixed winter
precipitation mainly northwest of terminals for the 06Z taf package
as midlevel dryslot advects over eastern Kansas and western
Missouri. Regional radar loops (supported by HRRR trends) indicates
most, if not all precipitation splitting around aerodrome sites
tonight; and have removed -rasn mention (sans a 1 hour tempo mention
at KSTJ where a wintry mix remains possible). Will need to watch
tail end of snow band over central Kansas should it begin to rotate
a bit further SE.
Based on upstream observations and bufr soundings have pushed cigs
into the upper end of mvfr late tonight and Tuesday morning. Could
potentially still see a period of lower end mvfr with overall
confidence not particularly high. Brisk sustained NW sfc winds will
quickly obtain gustiness as secondary caa blast moves into the area
per KS/NE obs; and remain sustained aoa 13kt throughout the daylight
hours Tuesday before decoupling with sunset.
21
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1135 PM CST Mon Jan 16 2012
...UPDATED AVIATION...
.DISCUSSION...
Dry air and good mixing prevented many low clouds from developing
today which allowed temperatures to soar well into the 60s across the
southeast 3/4 of the forecast area. Meanwhile a cold front continues
to organize and slowly push south into far northern Missouri late
this afternoon. This front will accelerate southward this evening as
a weak shortwave tracks into the Central Plains. As this feature
interacts with the front and low level wind fields increase, a band
of frontogenesis will develop in the 900-800 hPa layer across the
southern half of the area late this evening. This should allow
scattered light precipitation to develop across eastern Kansas into
central Missouri after sunset, which will likely grow in intensity
and coverage across far southern portions of the area after 06Z as
frontogenesis intensifies. An elevated theta-e maximum near 850-hPa
may allow for some elevated thunder as well, especially across the
southern third of the forecast area.
Meanwhile further north, an additional band of postfrontal light
snow will expand out of the Dakotas into Nebraska and Iowa overnight
ahead of the upper wave. Expect the bulk of this activity to remain
north of the forecast area in a region of better upper level support,
though some light accumulating snow (or sleet) may be possible as far
south as Highway 36 where weak deformation and convergence will set
up along the lagging 850 hPa front. Interestingly, the 18Z run of the
NAM is producing between 0.2 and 0.3 inches of QPF across the
northern forecast area overnight. This seems to be an anomalous run
as its forecast deep moisture profile is much more moist than
previous runs, which doesn`t seem supported by looking upstream.
Between this and the shower and thunderstorm activity further south,
there may be a relative minimum in precipitation across the KC-Macon
corridor for much of the night. However, still can`t rule out some
light precip across these areas toward midnight given the broad
ascent ahead of the upper wave. Thermal profiles suggest that any
precipitation that does develop overnight would initially be rain
south of Highway 36, before transitioning to a light wintry mix
across the KC- Macon corridor around 08Z and across central Missouri
by 11Z. At this time precipitation amounts look to be much too light
by the time this transition occurs to produce any measurable snow or
ice accumulation.
This system will shift into the Great Lakes on Tuesday with deep cold
air advection spreading into the region. Skies should gradually clear
from west to east through the day, though concerned that models may
be moving the clearing line too quickly across the forecast area as
they often do in similar CAA regimes. A large surface high will be
quick to build into the region by Tuesday afternoon, shifting into
the Mississippi Valley by 12Z Weds. This will allow temperatures to
fall into the teens, though didn`t go quite as cold as guidance
numbers given how quickly winds will increase from the south after
09Z. Warm air advection will send temperatures back above average by
Wednesday while skies remain mostly sunny.
Hawblitzel
Medium Range (Thursday - Sunday):
Models show reasonable agreement with the upper level pattern
through the extended with nearly zonal to northwesterly flow
prevailing. There is also decent agreement tracking a wave through
the flow Friday into Saturday. The ECMWF is a little more aggressive
with the mid level circulation associated with short wave and as a
result depicts a bit more QPF. Prefer the GFS which keeps the mid
level wave open and therefore not as aggressive with any possible
precipitation. Will keep only slight chances in for the northeastern
half of the forecast area for Friday as this systems tracks through
given the preference for a drier short wave passage. Beyond the
small chances for precipitation on Friday for a portion of the
forecast area the rest of the forecast looks to be above to well
above normal with highs returning to the 50s on Sunday. The next
shot of precipitation may come early next week with models showing a
deep trough coming out of the southwest. This seems to correspond to
the arctic oscillation heading to more of a neutral to slightly
negative outlook per the GFS ensemble data which would indicate
colder temperatures for the area. But this is well into the future
and beyond the scope/timeframe of this forecast so we`ll continue to
monitor trends and see how the pattern evolves over the next 7-8
days.
CDB
&&
.AVIATION...
Thunderstorms remain well south of terminals and mixed winter
precipitation mainly northwest of terminals for the 06Z taf package
as midlevel dryslot advects over eastern Kansas and western
Missouri. Regional radar loops (supported by HRRR trends) indicates
most, if not all precipitation splitting around aerodrome sites
tonight; and have removed -rasn mention (sans a 1 hour tempo mention
at KSTJ where a wintry mix remains possible). Will need to watch
tail end of snow band over central Kansas should it begin to rotate
a bit further SE.
Based on upstream observations and bufr soundings have pushed cigs
into the upper end of mvfr late tonight and Tuesday morning. Could
potentially still see a period of lower end mvfr with overall
confidence not particularly high. Brisk sustained NW sfc winds will
quickly obtain gustiness as secondary caa blast moves into the area
per KS/NE obs; and remain sustained aoa 13kt throughout the daylight
hours Tuesday before decoupling with sunset.
21
&&
.EAX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
WFO EAX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1059 PM CST MON JAN 16 2012
.UPDATE...
/920 PM CST MON JAN 16 2012/
HAVE MADE UPDATES TO GO WITH LIKELY POPS THE REST OF THE EVENING
WHERE SHOWERS AND THUNDERSTORMS HAD DEVELOPED OVER MID MISSOURI.
THE HRRR HAS DONE A DECENT JOB THIS EVENING DEPICTING THIS
DEVELOPMENT...AND SHOWS IT MOVING EAST NORTHEASTWARD TOWARD THE MS
RIVER. SHOWERS AND THUNDERSTORMS HAVE ALSO DEVELOPED OVER SOUTHEASTERN
KANSAS AHEAD IN RESPONSE TO INCREASING ASCENT AHEAD OF A SHORTWAVE
CURRENTLY MOVING ACROSS THE CENTRAL PLAINS. EXPECT THIS AREA TO
SPREAD EAST INTO CENTRAL AND SOUTHEAST MISSOURI BY 06Z...SO LIKELY
AND CATEGORICAL POPS OVER THE SOUTHEAST TWO THIRDS OF THE CWA
OVERNIGHT STILL LOOKS GOOD. RUC STILL DEPICTS THAT BEST VERTICAL
MOTION WILL BE EXITING THE AREA JUST AHEAD OF WHEN LOW LEVEL
THERMAL PROFILES WILL SWITCH OVER TO SNOW OR SLEET. GOING FORECAST
FOR A BRIEF SWITCH OVER TO SNOW WITH LITTLE ACCUMULATION OVER
NORTHERN MISSOURI AND WEST CENTRAL ILLINOIS STILL LOOKS
GOOD...WITH FLURRIES LINGERING INTO TUESDAY MORNING.
BRITT
&&
.DISCUSSION...
/313 PM CST MON JAN 16 2012/
IT WAS THE CLOUDS. SC CLOUD FIELD WAS ABOUT 4-6 HOURS DELAYED IN
GETTING IN HERE AND NEVER DEVELOPED THAT WELL SINCE IT OCCURRED
DURING THE DAY...AND WITH FULL SUNSHINE FOR A GOOD PART OF THE DAY
AND A STOUT SW WIND GUSTING TO 40MPH AT TIMES...TEMPS SURGED TO NEAR
RECORD LEVELS THIS AFTERNOON IN SOMETHING THAT WAS MORE REMINISCENT
OF MID APRIL THAN MID JANUARY. IN FACT...A RECORD MAX TEMP WAS
BROKEN AT KCOU OF 70 DEGREES...WITH THE RECORD TEMP OF 71 AT KSTL
BEING THREATENED. WEAK LO PRES EXISTED OVER N CNTRL MO AT 20Z WITH
A CDFNT EXTENDING TO THE NE AND SW OF THIS LO PRES THRU ERN IA AND
ERN KS. A WRMFNT HAS PUSHED INTO THE FAR NERN FA IN CNTRL IL.
APPROACH OF LEAD MID LEVEL SHORTWAVE THIS EVENING AND SFC CDFNT
IMMERSING ITSELF IN AN EVER INCREASINGLY MOIST ATMOSPHERE SHOULD
FINALLY LEAD TO BREAKOUT OF PCPN...ESPECIALLY LATE THIS EVENING...
WITH IT REACHING ITS PEAK OVERNIGHT...WITH HI PROBABILITIES COVERING
AREAS ALONG-SE FROM CNTRL MO TO CNTRL IL. ENOUGH ELEVATED
INSTABILITY WILL MOVE IN WITH THIS PCPN TO WARRANT CONTINUED MENTION
OF DECENT PROBS FOR TSRA...WITH CAPES OF 200-300 J/KG...MAINLY FOR
AREAS ALONG-S OF I-70. COULD STILL SEE BRIEFLY A POTPOURRI OF PCPN
TYPES LATE TONIGHT FOR PARTS OF NE-CNTRL MO AND W CNTRL IL BEFORE
FIRST DRY PUNCH COMES IN...BUT EXPECTED BREVITY AND INTENSITY OF
PCPN SHOULD BE SUCH WHERE LITTLE OR NO ACCUM WILL BE SEEN. AHEAD OF
THE FRONT...TEMPS SHOULD REMAIN QUITE MILD...WITH READINGS OF 50+
BUT LOOK FOR A RAPID TEMP DROP OFF INTO THE 30S BEHIND THE FRONT...
EVENTUALLY INTO THE MID-UPR 20S FOR PARTS OF NE-CNTRL MO AND W CNTRL
IL. SO NOT QUITE THE SAME PUNCH AS THE LAST FRONT AND SNOW EVENT
WITH OUR DROP INTO THE UPPER TEENS. FAVORED THE WARMER MOS FOR MIN
TEMPS TONIGHT FOR AREAS N AND W OF STL METRO WHILE OUTRIGHT GOING
ABOVE IT FOR AREAS WHERE THE FRONT WILL MAKE A VERY LATE PASSAGE.
RAIN SHOULD LINGER OVER AREAS S AND E OF STL METRO PAST 12Z WHERE
FROPA IS NOT EXPECTED TO OCCUR YET...WITH JUST DRIZZLE OR FLURRIES
LEFTOVER ELSEWHERE DURING THE MORNING UNTIL SECOND AND FINAL DRY
PUNCH PUSHES THRU WITH TRANSITION TO ANTICYCLONIC SFC FLOW. MOS
TEMP TRENDS FROM TONIGHT SHOULD CONTINUE WITH MOS BLEND FAVORED FOR
AREAS N AND W OF STL METRO WHILE ABOVE THE HIGHEST MOS FOR AREAS S
AND E OF STL METRO DUE TO THE DIFFERENT WAYS MOS MAX/MIN TEMPS ARE
CALCULATED VERSUS THE FCST. DECENT BUST POTENTIAL ON TEMPS TONIGHT
AND TOMORROW DUE TO THE TIMING OF THE FRONT AND SHARP GRADIENT IT
WILL CARRY WITH IT...AN HOUR OR TWO OFF ON TIMING WILL MAKE A BIG
DIFFERENCE.
MODELS ARE A TAD FASTER ON TRANSLATIONAL SPEED OF HI PRES AXIS
TUESDAY NIGHT...AND HAVE TWEAKED MIN TEMPS UP FOR KUIN-KCOU AREAS
BUT CONTINUED AOB LOWEST MOS ELSEWHERE.
GFS HAS COME IN CONSIDERABLY COLDER WITH WEDNESDAY NIGHT/EARLY
THURSDAY CDFNT WHILE THE NAM AND ECMWF NOT SO MUCH. FOR NOW WENT
WITH A BLEND AS MOST MODELS WANT TO GIVE US A GLANCING BLOW WITH
THIS AIRMASS AND NOT A DIRECT HIT.
MEDIUM RANGE FOR THE WEEKEND AND EARLY NEXT WEEK STILL LOOKS IFFY ON
THE DETAILS BUT BROAD PICTURE STILL LOOKS CONSISTENT...SHOWING A
PROGRESSIVE FLOW TRANSITIONING TO AN APPROACHING TROF FROM THE W.
THIS SHOULD INDICATE OVERALL MILD TEMPS WITH SPOTTY PCPN CHCS. THE
FRIDAY EVENT STILL LOOKS THE SAME WITH LO PROBS FOR LIGHT MIXED PCPN
WITH BETTER CHCS AHEAD OF THE DEEP TROF ON MONDAY.
TES
&&
.AVIATION...
/1025 PM CST MON JAN 16 2012/
SFC LOW JUST E OF UIN WITH CDFNT EXTENDING SW OF LOW THROUGH COU
AND SWRN MO...JUST N OF JLN. THIS SFC LOW WILL DEEPEN AS IT MOVES
NEWD DRAGGING THE CDFNT SEWD THROUGH STL/SUS LATE TGT. THE SFC
WIND WILL VEER AROUND TO A W-NWLY DIRECTION AFTER FROPA LATE TGT
IN STL/SUS. SHOWERS AND STORMS WILL CONTINUE TO MOVE NEWD ALONG
THE CDFNT LATE TGT. THE CEILING WILL CONTINUE TO LOWER AFTER FROPA
DOWN TO AROUND 1000-1500 FT. MAY HAVE A BRIEF PERIOD OF SNOW IN
UIN BEFORE THE PRECIPITATION SHUTS OFF LATE TGT/EARLY TUE
MRNG...OTHERWISE LITTLE IF ANY WINTRY PRECIPITATION IS EXPECTED AT
THE OTHER TAF SITES. THE CLOUD CEILING WILL GRADUALY RISE DURING
THE DAY ON TUE AS A STRONG SFC RIDGE BUILDS SEWD INTO MO. NWLY SFC
WINDS WILL BE QUITE STRONG AND GUSTY ON TUE DUE TO THE TIGHT SFC
PRESSURE GRADIENT BETWEEN THIS SFC RIDGE AND THE DEEPENING SFC LOW
MOVING NEWD THROUGH THE GREAT LAKES REGION. THE CLOUD CEILING
SHOULD SCATTER OUT TUE EVNG.
SPECIFICS FOR KSTL...SWLY SFC WINDS WILL VEER AROUND TO A W-NWLY
DIRECTION BY 09-10Z TUE AFTER FROPA. SHOWERS AND STORMS WILL MOVE
NEWD THROUGH STL LATE TGT. THE CEILING WILL FALL TO AROUND
1000-1500 FT AFTER FROPA. STRONG AND GUSTY NWLY SFC WINDS CAN BE
EXPECTED ON TUE...DIMINISHING TUE NGT AS THE SFC RIDGE AXIS MOVES
THROUGH. THE CEILING HEIGHT WILL GRADUALLY RISE DURING THE DAY ON
TUE...EVENTUALLY SCATTERING OUT BY EARLY TUE EVNG.
GKS
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
IL...NONE.
&&
$$
WFO LSX
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
103 AM EST TUE JAN 17 2012
.SYNOPSIS...
LOW PRESSURE WILL MOVE TO SOUTHERN MICHIGAN BY TUESDAY MORNING,
THEN CONTINUE TRACKING NORTHEAST INTO SOUTHEASTERN CANADA BY THE
AFTERNOON. THIS SYSTEM WILL BRING A LIGHT WINTRY MIX TO THE
REGION OVERNIGHT...INCLUDING SOME FREEZING RAIN. THE MIXED
PRECIPITATION WILL CHANGE OVER TO RAIN TUESDAY MORNING AS WARMER
AIR WORKS INTO THE AREA. A STRONG COLD FRONT WILL SWEEP THROUGH
TUESDAY EVENING...WITH GUSTY NORTHWEST WINDS THAT WILL PERSIST
INTO WEDNESDAY MORNING. LAKE EFFECT SNOW IS LIKELY SOUTHEAST OF
LAKE ONTARIO LATE TUESDAY NIGHT THROUGH EARLY WEDNESDAY AFTERNOON.
&&
.NEAR TERM /UNTIL 6 AM THIS MORNING/...
UPDATE AS OF 1030 PM...JUST TWEAKED POPS...TEMPS TO REFLECT ON-
GOING RADAR TRENDS. SECOND WAVE OF PRECIP WAS RAPIDLY DEVELOPING
AND TRACKING TO THE EAST AND SHUD OVERSPREAD ALL OF THE REGION BY
6Z. 00Z NAM SUGGESTS PRECIP TYPE SHUD REMAIN MAINLY SNOW ACRS NC
NY...UNTIL 9Z OR SO...AND A MIX OF ZR/IP REST OF NE PA AND SC NY
EXCEPT ALONG THE LAKE ONTARIO PLAIN WHERE DOWNSLOPING SHUD KEEP
SFC TEMPS ABV FREEZING DESPITE EVAP COOLING. THE PRECIP WILL BE
LIGHT SO NOT EXPECTING MUCH SNOW IN NC NY...1 TO 3 INCHES AT
BEST. REST OF AREA...LIGHT ICING MAINLY.
PREVIOUS DSCN BELOW...
RADAR SHOWS PRECIPITATION RAPIDLY DEVELOPING ACROSS NEW YORK AND
PENNSYLVANIA IN RESPONSE TO DEEP LAYER ISENTROPIC LIFT. CROSS-
SECTIONS REVEAL A LAYER ALMOST 400 MB THICK OF ISEN LIFT MAINLY
BTWN 900 AND 500 MB. LOOKING AT THE BIG PICTURE...THERE APPEARS TO
BE AT LEAST TWO WAVES OF PRECIPITATION INITIALLY. THE FIRST IS
DEVELOPING PRECIPITATION QUICKLY ACROSS EASTERN NY...WITH THE NEXT
ONE QUICKLY WORKING INTO WRN PA/SW NY ATTM. THE WAVE IN WRN PA/WRN
NY WILL LEAD TO WIDESPREAD LIGHT PRECIPITATION ACROSS ALL OF C NY
AND NE PA BTWN 3 AND 6Z THIS EVENING. IN THE GRIDS...I BASICALLY
EXTRAPOLATED UP TO CAT POPS FROM 30-40 POPS BY 6Z ACROSS ENTIRE
CWA.
AS FOR P-TYPE...I USED A 50-50 BLEND OF THE GFS AND NAM THICKNESS
TOOL IN GFE WHICH CAPTURES THE CHANGEOVER VERY WELL. THIS WAS USED
ON PREVIOUS SHIFT AND IT STILL LOOKS VERY MUCH ON TRACK. BIGGEST
QUESTION IS HOW MUCH SNOW WILL FALL ACROSS THE NERN PART OF
CWA AS 18Z NAM...18Z GFS...18Z LOCAL WRF AND LATEST RUC ALL
INDICATE FROM 1-3 INCHES OF SNOW AT KRME. GIVEN THE COLDER TEMP
PROFILES AND THE RAPIDLY DEVELOPING PRECIPITATION ATTM...THIS
LOOKS GOOD. REST OF AREA LESS THAN 1 INCH OF SNOW AND SLEET. SINCE
QPF AMNTS ARE NOT THAT HIGH I DON/T EXPECT MUCH MORE THAN A SMALL
COATING OF ICE IN CWA...HIGHEST WILL BE CATSKILLS TO UPR MOHAWK
VALLEY WHERE MAYBE .1 TO .2 INCHES OF ICE ACCUMS. EVEN THOUGH TEMPS ARE
ABV FREEZING IN PARTS OF THE CENTRAL SRN TIER/FINGER
LAKES...DEW POINTS ARE LOW ENUF THAT EVAP COOLING FROM PRECIPITATION
SHUD DROP TEMPS TO BELOW FREEZING. THIS OCCURRED IN PA THIS EVE AND
I SEE NO REASON WHY IT WON/T HAPPEN IN THE FINGER LAKES IN THE
NEXT COUPLE HOURS.
DECIDED TO HAVE ADVY IN EFFECT ALL AREAS AT 7 PM...AND WILL DROP
THE FINGER LAKES AREA BY ARND 3 AM...AS I BELIEVE FZRA WON/T LAST
THAT LONG. I ALSO BROKE OUT ONEIDA CO INTO ANTHR WSWSEGMENT TO HIT
THE SNOW A LITTLE HARDER. I ALSO ADDED SOME PATCHY FOG INTO THE
GRIDS ONCE THE SFC TEMPS GET CLSE TO AND ABV FRZG.
&&
.SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/...
TUESDAY...AREA WILL RESIDE IN WARM SECTOR, AS SFC LOW PRES TRACKS
THROUGH NEARBY SOUTHERN ONTARIO CHANGING ALL REMAINING MIXED
PRECIP OVER ERN/NRN SECTIONS TO JUST RAIN BY MID MORNING. LIGHT
RAIN WILL CONTINUE THROUGH THE DAYTIME PERIOD WITH COVERAGE
GENERALLY DECREASING BY LATE AFTERNOON.
TUESDAY NIGHT...A STRONG COLD FRONT MOVES THROUGH THE AREA BETWEEN
00Z-06Z. MODEL SOUNDINGS AND ISALLOBARIC RISE/FALL COUPLET
INDICATE THE POTENTIAL FOR FREQUENT WINDS GUSTS AROUND 40 MPH,
ESPECIALLY ALONG THE LAKE PLAIN AND IN THE WESTERN CATSKILLS. A
WIND ADVISORY MAY BE NEEDED BY LATER SHIFTS. SCATTERED RAIN
SHOWERS WILL CHANGE TO SNOW SHOWERS IMMEDIATELY BEHIND FRONT IN
STRONG CAA. AFTER 09Z, LES PARAMETERS BECOME FAVORABLE UNDER 280
FLOW. WILL CONTINUE WITH CAT POPS ACROSS ONEIDA COUNTY TOWARD
MORNING.
WEDNESDAY...LOW LEVEL FLOW VEERS TO AROUND 300 DEGREES BY 15Z WITH
T85 AROUND -16C. WENT WITH CAT POPS ACROSS ONONDAGA/MADISON/
ONEIDA COUNTIES WITH POPS LOWERING INTO THE CHC CATEGORY BY MID
AFTERNOON AS SYNOPTIC MOISTURE DECREASES ALONG WITH SFC RIDGING.
WITH FAVORABLE LES CONDITIONS FOR 12 HOURS ACCUMS WILL LIKELY
REQUIRE AN ADVISORY. (3-7 INCHES).
TEMPS ON WEDNESDAY WILL ONLY RISE A FEW DEGREES UNDER GOOD LOW
LEVEL CAA. MAXES WILL RANGE IN THE 20S.
WEDNESDAY NIGHT...SFC HIGH PRES WILL RESIDE OVER THE AREA WITH
MAINLY CLEAR TO PARTLY CLOUDY SKIES. LOW TEMPS WILL RANGE AROUND
ZERO IN THE EAST/NORTH TO THE TEENS PARTS WEST.
THURSDAY...SFC LOW PRES MOVING THROUGH THE UPPER GREAT LAKES ALONG
WITH A DECENT MID LEVEL TROF MAY SPREAD SNOW SHOWERS OVER THE
REGION DURING THE AFTERNOON. POPS WILL BE HIGHER WEST. MAXES WILL
RANGE IN THE MID 20S TO AROUND 30.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
UNSETTLED WEATHER WITH LOW AMPLITUDE NEAR ZONAL FLOW. NO BIG STORMS
EXPECTED WITH TEMPERATURES AT OR ABOVE NORMAL. THURSDAY NIGHT A COLD
FRONT GOES THROUGH. THIS TIME ALL PRECIPITATION WILL BE SNOW WITH
THE COLD AIR ENTRENCHED OVER THE NE US WITH THE UPPER LEVEL TROF.
FRIDAY ANOTHER BRIEF PERIOD OF LAKE EFFECT BEFORE HIGH PRESSURE
MOVES IN LATE FRIDAY AND FRIDAY EVENING. ANOTHER QUICK STORM MOVES
EAST NORTHEAST FROM THE SOUTHERN MISSISSIPPI VALLEY TO THE MID
ATLANTIC STATES SATURDAY THEN OFF THE NEW ENGLAND COAST SUNDAY. FOR
NOW THIS DOES NOT LOOK LIKE A BIG STORM...AND ONLY BRUSHES THE AREA
WITH LIGHT SNOW. FOR SUNDAY TO MONDAY WARM AIR ADVECTION AHEAD OF A
STRONG COLD FRONT IN THE PLAINS AND DEEP UPPER LEVEL TROF OVER THE
ROCKIES. WE COULD HAVE SOME WEAK LIGHT OVERRUNNING MIXED
PRECIPITATION WITH NUMEROUS SHORT WAVES AND WARM FRONTS LIFTING
NORTHEAST BUT FOR THE MOST PART SHOULD REMAIN DRY AND MILD.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
A WARM FRONT HAS BROUGHT PRECIPITATION TO THE AREA TONIGHT. WITH
COLD AIR AT THE SURFACE, A WIDE VARIETY OF PRECIPITATION TYPES HAS
BEEN OBSERVED TONIGHT. THEY HAVE INCLUDED SNOW, FREEZING RAIN, TO
JUST PLAIN RAIN. AS THE SURFACE COLD AIR IS SLOWLY PUSHED OUT, THE
PRECIP TYPE WILL EVENTUALLY CHANGE OVER TO ALL RAIN LATER THIS
MORNING. ALL ACCUMULATIONS ARE EXPECTED TO BE LIGHT. THE MAIN
BATCH OF PRECIPITATION HAS MOVED THROUGH MOST OF THE FORECAST AREA
AND ONLY SCATTERED SHOWERS ARE EXPECTED UNTIL LATE MORNING, WHEN A
MORE STEADY AREA OF ALL RAIN IS EXPECTED TO MOVE THROUGH.
CURRENTLY, THIS IS REFLECTED AS A TEMPO GROUP AS IT SHOULD NOT BE
A LONG LASTING EVENT. LATER THIS EVENING, A COLD FRONT WILL MOVE
THROUGH LATER TODAY AND WINDS WILL BECOME STRONG AND VERY GUSTY
THIS EVENING, WITH SOME GUSTS POSSIBLY EXCEEDING 40KTS IN
LOCALIZED AREAS.
HOWEVER, WINDS THIS MORNING WILL BE GENERALLY SOUTHERLY BETWEEN 5
AND 10 KTS TO LIGHT AND VARIABLE.
.OUTLOOK...
TUESDAY NIGHT TO WEDNESDAY...MVFR/IFR RESTRICTIONS IN RAIN SHOWERS
CHANGING TO SNOW SHOWERS. ALSO...STRONG NORTHWEST WINDS WITH
GUSTS REACHING AT LEAST 25-35 KTS.
WEDNESDAY NIGHT AND THURSDAY...MAINLY VFR BUT SOME SNOW SHOWERS AND MVFR
POSSIBLE IN NY. IMPROVING TO VFR EVERYWHERE THU AFTN.
THU NGT TO FRIDAY...MVFR. LIGHT SNOW CHANGING TO LAKE EFFECT SNOW
IN NY.
SATURDAY...MVFR IN SNOW SHOWERS.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
PAZ038>040-043-044-047-048-072.
NY...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR
NYZ009-024-036-037-044>046-055>057-062.
WINTER WEATHER ADVISORY UNTIL 3 AM EST EARLY THIS MORNING FOR
NYZ017-018-022-023-025.
&&
$$
SYNOPSIS...DJN/RRM
NEAR TERM...DJN
SHORT TERM...RRM
LONG TERM...TAC
AVIATION...SLI
AREA FORECAST DISCUSSION
NWS RALEIGH NC
151 PM EST TUE JAN 17 2012
.SYNOPSIS...
ABOVE NORMAL TEMPERATURES AND BREEZY SOUTHWEST WINDS ARE EXPECTED
THIS AFTERNOON AHEAD OF AN APPROACHING COLD FRONT. A LINE OF SHOWERS
WILL ACCOMPANY THE COLD FRONT AS IT CROSSES THE AREA OVERNIGHT.
NEAR NORMAL TEMPERATURES AND DRY CONDITIONS ARE EXPECTED IN THE WAKE
OF THE FRONT WEDNESDAY AND THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1115 AM TUESDAY...
OVERVIEW:
A ROBUST NORTHERN STREAM SHORTWAVE APPROACHING THE UPPER MS RIVER
VALLEY AS OF 15Z WILL PROGRESS INTO THE GREAT LAKES BY 00Z AND INTO
NEW ENGLAND BY 12Z WED. AN ATTENDANT 1000 MB SURFACE LOW CENTERED
OVER SOUTHERN MICHIGAN AT 15Z WILL QUICKLY DEEPEN TO 990 MB AS IT
PROGRESSES TO THE LOWER GREAT LAKES BY 00Z...AND TO 985 MB AS IT
PROGRESSES TO NORTHERN MAINE BY 12Z WED. AN ASSOCIATED COLD FRONT
WILL PROGRESS EASTWARD TO THE SOUTHERN APPALACHIANS BY 00Z...AND TO
THE CAROLINA COAST BY OR SHORTLY AFTER 12Z WED. ADDITIONAL UPPER
LEVEL ENERGY UPSTREAM OVER TX AND THE LOWER MS RIVER VALLEY AT 15Z
IS PROGGED TO PROGRESS ENE INTO THE CAROLINAS/MID-ATLANTIC OVERNIGHT.
PRECIPITATION CHANCES TODAY:
CURRENT LIGHT RAIN MOVING ACROSS THE MOUNTAINS APPEARS TO BE ASSOC/W
AN UPPER LEVEL DISTURBANCE (NOTED IN RUC H3 VORTICITY). THIS FEATURE
IS PROGGED TO PROGRESS THROUGH NORTHERN VA BY 18Z AND THEN OFFSHORE
BY 21Z. ALTHOUGH IT IS POSSIBLE THAT SOME OF THIS ACTIVITY MAY CROSS
THE MOUNTAINS AND PRODUCE A FEW SPRINKLES OR AN ISOLD SHOWER...DO
NOT ANTICIPATE MUCH IN THE WAY OF MEASURABLE PRECIP...AND WILL LEAVE
A SLIGHT CHANCE OF SPRINKLES WEST OF HWY 1 THROUGH EARLY AFTERNOON.
OTHERWISE...WITH UNIDIRECTIONAL FLOW ALOFT AND IN THE LOWER LEVELS
AND LIFT GENERALLY CONFINED TO WEAK/BROAD LOW-LEVEL WARM
ADVECTION...FEEL THAT FORCING SHOULD BE INSUFFICIENT TO WARRANT
MEASURABLE PRECIPITATION CHANCES TODAY...ALTHOUGH AN ISOLD SHOWER OR
TWO CANNOT BE RULED OUT.
PRECIPITATION CHANCES TONIGHT:
CHANCES INCREASE THIS EVENING/TONIGHT FROM THE W/NW AS THE
AFOREMENTIONED FRONTAL ZONE MOVES INTO CENTRAL NC FROM THE W/NW.
EXCELLENT LOW-LEVEL CONVERGENCE IS PROGGED IN ASSOC/W THE SFC-925 MB
TROUGH...AND SOME UPPER LEVEL SUPPORT IS EXPECTED AS SUBTLE
SHORTWAVES EMBEDDED UPSTREAM (TX/LOWER MS RIVER VALLEY) IN WSW FLOW
ALOFT PROGRESS INTO THE CAROLINAS LATER THIS EVENING/TONIGHT. THE
GFS/NAM/ECMWF ALL SHOW MEASURABLE PRECIP OVER CENTRAL NC TONIGHT.
COVERAGE IS DIFFICULT TO ASCERTAIN STILL...THOUGH...AND THE HIGH RES
WRF-NMM 1KM REFLECTIVITY PRODUCT INDICATES THAT PRECIP WILL MOST
LIKELY BE IN THE FORM OF A NARROW LINE OR BROKEN LINE OF SHOWERS
THAT DEVELOPS IN VICINITY OF THE SURFACE FRONT AS IT PROGRESSES
NW-SE THROUGH THE AREA BETWEEN ROUGHLY 03-12Z. WITH THE
AFOREMENTIONED UNCERTAINTY...WILL KEEP PRECIP CHANCES NO HIGHER THAN
60-80%...WITH THE BEST CHANCES IN THE SW PIEDMONT...SANDHILLS AND SE
COASTAL PLAIN. ALTHOUGH SFC-BASED INSTABILITY IS UNLIKELY GIVEN POOR
DIURNAL TIMING AND DEWPOINTS IN THE MID 40S THE LOWER 50S AT
BEST...STEEP MID-LEVEL LAPSE RATES WILL HELP CONTRIBUTE TO THE
POTENTIAL FOR WEAK ELEVATED INSTABILITY...AND A FEW LIGHTNING
STRIKES CANNOT BE RULED OUT IF THE CORRECT JUXTAPOSITION OF
LOWER/UPPER LEVEL FORCING OCCURS DURING FROPA.
WIND:
DUE TO A TIGHT HEIGHT/MSLP GRADIENT AHEAD OF THE FRONT AND LOW-LEVEL
TROUGH...AN IMPRESSIVE SOUTHWESTERLY LLJ WAS PRESENT THIS MORNING ON
THE 12Z RAOBS...WITH GSO/RNK REPORTING 50 KT AT H85 AND UPSTREAM
RAOBS BNA/ILN REPORTING 65-75 KT. THE 12Z GSO SOUNDING ACTUALLY
INDICATED 50 KT SW FLOW AS LOW AS 1500 FT AGL. FCST SOUNDINGS SHOW
40-50 KT FLOW AS LOW AS 2000-3000 FT AGL ACROSS CENTRAL NC THIS
AFTERNOON. LUCKILY...WIDESPREAD MID-LEVEL CLOUD COVER MOVING INTO
THE AREA FROM THE WEST WILL LIMIT DIURNAL HEATING/MIXING AND
LOW-LEVEL WARM ADVECTION SHOULD RESULT IN AN INVERSION AOA 925 MB.
THESE FACTORS SHOULD PREVENT THE TOP OF THE MIXED LAYER FROM
EXCEEDING ~2500 FT AND HELP PREVENT THE STRONGEST LOW-LEVEL FLOW
FROM MIXING DOWN. HOWEVER...UNCERTAINTY PERSISTS...AND IT IS
POSSIBLE SOME LOCATIONS COULD SEE SUSTAINED WINDS OF 25 KT AND GUSTS
UP TO 40 KT FOR A BRIEF PERIOD THIS AFTERNOON...ESPECIALLY IN THE
EAST WHERE MORE SUNSHINE THIS MORNING WILL ALLOW FOR BETTER MIXING.
WILL CONTINUE TO HIGHLIGHT THE POTENTIAL FOR GUSTY WINDS IN THE
HWO...AND WILL ISSUE AN SPS OR SHORT-FUSED WIND ADVISORY IF BREAKS
IN CLOUD COVER OR STRONGER LOW-LEVEL FLOW THAN ANTICIPATED RESULT IN
FREQUENT WIND GUSTS APPROACHING OR EXCEEDING 40 KT.
TEMPERATURES:
WITH BREEZY SOUTHWEST FLOW AND 1000-850 MB THICKNESSES PROGGED AT
~1360 METERS...EXPECT HIGHS RANGING FROM 60-68F...COOLEST NW AND
WARMEST E/SE. OVERNIGHT...LOWS WILL DEPEND PRIMARILY ON THE TIMING
OF THE FRONTAL PASSAGE AND THE COVERAGE OF SHOWER ACTIVITY PRIOR
TO/DURING FROPA. EXPECT LOWS TO RANGE FROM THE MID/UPPER 30S TO
LOWER 40S N/NW...TO MID/UPPER 40S TO LOWER 50S S/SE. -VINCENT
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 255 PM MONDAY...
FOR WEDNESDAY/WEDNESDAY NIGHT: THE NAM IS A BIT SLOWER THAN THE GFS
TO PUSH THE FRONT AND PRECIP EAST OF THE CWA WEDNESDAY MORNING...
BUT IT HAS SUPPORT FROM THE ECMWF AND WILL LEAN TOWARD THIS SOLUTION
BY RETAINING CHANCE POPS IN THE SOUTHEAST FOR A FEW HOURS IN THE
MORNING. OTHERWISE... BRISK NW WINDS WILL BRING IN MUCH COOLER AIR
THROUGH THE DAY WITH 850 MB TEMPS FALLING NEARLY 18C FROM TUESDAY
EVENING TO WEDNESDAY EVENING. TEMPS ARE LIKELY TO RISE JUST A FEW
DEGREES FROM THE FAIRLY MILD MORNING LOWS IN MOST LOCATIONS. NET
HIGHS WILL BE 44-56... ALTHOUGH IN THE SOUTHEAST CWA THESE HIGHS
WILL OCCUR IN THE MORNING WITH STEADY OR FALLING READINGS THROUGH
THE DAY. EXPECT PARTLY TO MOSTLY SUNNY SKIES AS SURFACE HIGH
PRESSURE BUILDS IN FROM THE WEST. BUT MODELS DEPICT A STRONG
VORTICITY MAX TRACKING ACROSS NC WEDNESDAY NIGHT... AND WHILE THE
COLUMN IS LIKELY TO BE TOO STABLE AND LACKING ENOUGH DEEP MOISTURE
FOR ANY PRECIP WITH THIS FEATURE... A SHOT OF MOSTLY CLOUDY SKIES IS
LIKELY. LOWS 23-28. -GIH
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 1230 PM TUESDAY...
THE OVERALL PATTERN ACROSS THE LOWER 48 WILL CONTINUE TO FEATURE ONE
THAT IS TYPICAL OF LA NINA WINTERS. OVERALL...THE TENDENCY FOR ABOVE
NORMAL HEIGHTS AND ABOVE NORMAL TEMPERATURES WILL CONTINUE FOR THE
EASTERN STATES...WITH A DEVELOPING UPPER LOW EXPECTED OVER THE
SOUTHWESTERN U.S. NEXT WEEK. MUCH ABOVE NORMAL TEMPERATURES SHOULD
VISIT OUR REGION EARLY TO MID NEXT WEEK.
WE WILL BEGIN COLD ON THURSDAY MORNING. HOWEVER...THE PROGRESSIVE
SURFACE HIGH WILL RAPIDLY MOVE OFFSHORE EARLY IN THE DAY LEADING TO
WAA. MOST MODELS GENERALLY INDICATE INCREASING CLOUDINESS WITH THE
WAA PATTERN THURSDAY WHICH WOULD LEAD TO A SLIGHT DELAY IN THE
UPCOMING WARMING TREND LATE IN THE WEEK. THURSDAY MAY END UP BEING
MUCH LIKE THIS PAST MONDAY WHEN CLOUDS RACED IN AND KEPT
TEMPERATURES MUCH COOLER THAN THEY WOULD HAVE BEEN GIVEN THE WAA
PATTERN. A SIMILAR SET UP THURSDAY SUPPORTS HIGHS THAT WILL BE
COOLER THAN MOS GUIDANCE... LEANING TOWARD THE COOLEST MET NUMBERS
IN THE 45-50 RANGE NW TO LOWER 50S SE. NOTHING MORE THAN A FEW
SPRINKLES WILL BE FORECAST WITH THE LACK OF ANY UPPER FORCING IN THE
RETURN FLOW PATTERN.
FOR THURSDAY NIGHT AND FRIDAY...ANOTHER FAST MOVING COLD FRONT IS
FORECAST TO APPROACH THE STATE THURSDAY NIGHT AND FRIDAY MORNING
WITH LITTLE MOISTURE RETURN INDICATED. PLENTY OF MID LEVEL
CLOUDINESS AND A SW BREEZE SHOULD KEEP TEMPERATURES MILD OUT AHEAD
OF THE FRONT THURSDAY NIGHT. EXPECT MOST AREAS TO SEE LOWS REMAIN IN
THE MID TO UPPER 30S. FRIDAY...A MODEST 1025 MB SURFACE HIGH IS
EXPECTED TO BUILD IN FROM THE NORTH. THIS WILL LEAD TO CAA AND
DRYING. TEMPERATURES SHOULD BE MOSTLY IN THE 50S.
FOR FRIDAY NIGHT THROUGH THE WEEKEND...A GENERALLY REPEATING PATTERN
WITH THE HIGH EXITING TO THE EAST...A WAA RETURN FLOW ESPECIALLY
SATURDAY INTO SATURDAY NIGHT. THIS WILL BE FOLLOWED BY ANOTHER FAST
MOVING LOW PRESSURE EXPECTED TO TRACK NE FROM THE TENNESSEE VALLEY
TO THE NORTHERN MID-ATLANTIC STATES AND OFFSHORE BY EARLY SUNDAY.
THE TRAILING COLD FRONT IS FORECAST TO PUSH EAST THROUGH NC BY 12Z
SUNDAY. THE HIGHEST POP SHOULD BE LATE SAT AND SAT NIGHT IN THE
WEST... AND IN THE EAST SAT NIGHT INTO EARLY SUNDAY. AFTER MORNING
LOWS IN THE 40-45 RANGE HIGHS SHOULD SOAR INTO THE 60S SATURDAY...
THEN REMAIN IN THE UPPER 40S AND 50S SATURDAY NIGHT. HIGHS SUNDAY
SHOULD BE MOSTLY IN THE 60S WITH SOME UPPER 50S NW.
MONDAY AND TUESDAY...BUILDING HEIGHTS OVER THE SE STATES COMBINED
WITH MILD PACIFIC AIR OVER THE REGION SHOULD YIELD TEMPERATURES 20
TO 25 DEGREES ABOVE NORMAL. THIS SHOULD BE MOST NOTED AT NIGHT WHEN
LOWS MAY STAY WELL IN THE 50S (NEARLY 30 DEGREES ABOVE NORMAL)...
DEPENDING ON THE AMOUNT OF CLOUDINESS. -BADGETT
&&
.AVIATION /18Z TUESDAY THROUGH SATURDAY/...
AS OF 145 PM TUESDAY...
24-HR TAF PERIOD:
VFR CONDITIONS (ASIDE FROM ISOLD MVFR CEILINGS) ARE EXPECTED THROUGH
00Z THIS EVENING...WITH A PERIOD OF IFR (AND PERHAPS LIFR)
CONDITIONS ASSOCIATED WITH SHOWERS DEVELOPING OVERNIGHT AS A COLD
FRONT PROGRESSES THROUGH THE AREA FROM NW-SE. BREEZY SOUTHWEST WINDS
WILL OCCUR EVERYWHERE THIS AFTERNOON/EVENING AHEAD OF THE COLD
FRONT...SUSTAINED AT 15-25 KT WITH GUSTS UP TO 30-35 KT. WINDS WILL
REMAIN BREEZY AFTER SUNSET AHEAD OF THE FRONT...ALTHOUGH SUSTAINED
WIND SPEEDS/GUSTS MAY DECREASE 5-10 KT FROM PEAK AFTERNOON WINDS.
THE LATEST 12Z GUIDANCE SHOWS THE COLD FRONT PROGRESSING SOUTHEAST
THROUGH CENTRAL NC BETWEEN 06-12Z WED...FIRST AT INT/GSO...FOLLOWED
BY RDU...AND FINALLY RWI/FAY. PRECIP CHANCES AND SUB-VFR CEILINGS
WILL OCCUR PRIMARILY BEFORE THE FRONTAL PASSAGE AT INT/GSO...WHEREAS
THE REMAINING TAF SITES ARE MORE APT TO SEE THE BEST CHANCE FOR
PRECIP AND SUB-VFR CONDITIONS ALONG AND IMMEDIATELY BEHIND THE
FRONT. WINDS WILL RAPIDLY SHIFT TO THE NORTHWEST AT ~15 KT SUSTAINED
WITH GUSTS UP TO ~25 KT IN THE WAKE OF THE FRONT. VFR CONDITIONS ARE
EXPECTED TO RETURN IN THE WAKE OF THE FRONT BY OR SHORTLY AFTER 12Z
WED MORNING...WITH WINDS BECOMING NORTHERLY AT 10-15 KT BY THE END
OF THE TAF PERIOD (18Z WED).
LOOKING AHEAD:
VFR CONDITIONS WILL RULE IN THE WAKE OF THE FRONT ON WED/THU/FRI. A
LOW PRESSURE SYSTEM APPROACHING THE AREA FROM THE WEST AND A
DEVELOPING FRONTAL ZONE OVER THE CAROLINAS COULD RESULT IN SUB-VFR
CONDITIONS FRI NIGHT THROUGH THE DAY SAT AND POSSIBLY THROUGH SAT
NIGHT AS WELL. HOWEVER...A LARGE DEGREE OF UNCERTAINTY PERSISTS
W/REGARD TO THE SPECIFICS OF THIS SYSTEM. -VINCENT
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...HARTFIELD
LONG TERM...BADGETT
AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1230 PM EST TUE JAN 17 2012
.SYNOPSIS...
ABOVE NORMAL TEMPERATURES AND BREEZY SOUTHWEST WINDS ARE EXPECTED
THIS AFTERNOON AHEAD OF AN APPROACHING COLD FRONT. A LINE OF SHOWERS
WILL ACCOMPANY THE COLD FRONT AS IT CROSSES THE AREA OVERNIGHT.
NEAR NORMAL TEMPERATURES AND DRY CONDITIONS ARE EXPECTED IN THE WAKE
OF THE FRONT WEDNESDAY AND THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1115 AM TUESDAY...
OVERVIEW:
A ROBUST NORTHERN STREAM SHORTWAVE APPROACHING THE UPPER MS RIVER
VALLEY AS OF 15Z WILL PROGRESS INTO THE GREAT LAKES BY 00Z AND INTO
NEW ENGLAND BY 12Z WED. AN ATTENDANT 1000 MB SURFACE LOW CENTERED
OVER SOUTHERN MICHIGAN AT 15Z WILL QUICKLY DEEPEN TO 990 MB AS IT
PROGRESSES TO THE LOWER GREAT LAKES BY 00Z...AND TO 985 MB AS IT
PROGRESSES TO NORTHERN MAINE BY 12Z WED. AN ASSOCIATED COLD FRONT
WILL PROGRESS EASTWARD TO THE SOUTHERN APPALACHIANS BY 00Z...AND TO
THE CAROLINA COAST BY OR SHORTLY AFTER 12Z WED. ADDITIONAL UPPER
LEVEL ENERGY UPSTREAM OVER TX AND THE LOWER MS RIVER VALLEY AT 15Z
IS PROGGED TO PROGRESS ENE INTO THE CAROLINAS/MID-ATLANTIC OVERNIGHT.
PRECIPITATION CHANCES TODAY:
CURRENT LIGHT RAIN MOVING ACROSS THE MOUNTAINS APPEARS TO BE ASSOC/W
AN UPPER LEVEL DISTURBANCE (NOTED IN RUC H3 VORTICITY). THIS FEATURE
IS PROGGED TO PROGRESS THROUGH NORTHERN VA BY 18Z AND THEN OFFSHORE
BY 21Z. ALTHOUGH IT IS POSSIBLE THAT SOME OF THIS ACTIVITY MAY CROSS
THE MOUNTAINS AND PRODUCE A FEW SPRINKLES OR AN ISOLD SHOWER...DO
NOT ANTICIPATE MUCH IN THE WAY OF MEASURABLE PRECIP...AND WILL LEAVE
A SLIGHT CHANCE OF SPRINKLES WEST OF HWY 1 THROUGH EARLY AFTERNOON.
OTHERWISE...WITH UNIDIRECTIONAL FLOW ALOFT AND IN THE LOWER LEVELS
AND LIFT GENERALLY CONFINED TO WEAK/BROAD LOW-LEVEL WARM
ADVECTION...FEEL THAT FORCING SHOULD BE INSUFFICIENT TO WARRANT
MEASURABLE PRECIPITATION CHANCES TODAY...ALTHOUGH AN ISOLD SHOWER OR
TWO CANNOT BE RULED OUT.
PRECIPITATION CHANCES TONIGHT:
CHANCES INCREASE THIS EVENING/TONIGHT FROM THE W/NW AS THE
AFOREMENTIONED FRONTAL ZONE MOVES INTO CENTRAL NC FROM THE W/NW.
EXCELLENT LOW-LEVEL CONVERGENCE IS PROGGED IN ASSOC/W THE SFC-925 MB
TROUGH...AND SOME UPPER LEVEL SUPPORT IS EXPECTED AS SUBTLE
SHORTWAVES EMBEDDED UPSTREAM (TX/LOWER MS RIVER VALLEY) IN WSW FLOW
ALOFT PROGRESS INTO THE CAROLINAS LATER THIS EVENING/TONIGHT. THE
GFS/NAM/ECMWF ALL SHOW MEASURABLE PRECIP OVER CENTRAL NC TONIGHT.
COVERAGE IS DIFFICULT TO ASCERTAIN STILL...THOUGH...AND THE HIGH RES
WRF-NMM 1KM REFLECTIVITY PRODUCT INDICATES THAT PRECIP WILL MOST
LIKELY BE IN THE FORM OF A NARROW LINE OR BROKEN LINE OF SHOWERS
THAT DEVELOPS IN VICINITY OF THE SURFACE FRONT AS IT PROGRESSES
NW-SE THROUGH THE AREA BETWEEN ROUGHLY 03-12Z. WITH THE
AFOREMENTIONED UNCERTAINTY...WILL KEEP PRECIP CHANCES NO HIGHER THAN
60-80%...WITH THE BEST CHANCES IN THE SW PIEDMONT...SANDHILLS AND SE
COASTAL PLAIN. ALTHOUGH SFC-BASED INSTABILITY IS UNLIKELY GIVEN POOR
DIURNAL TIMING AND DEWPOINTS IN THE MID 40S THE LOWER 50S AT
BEST...STEEP MID-LEVEL LAPSE RATES WILL HELP CONTRIBUTE TO THE
POTENTIAL FOR WEAK ELEVATED INSTABILITY...AND A FEW LIGHTNING
STRIKES CANNOT BE RULED OUT IF THE CORRECT JUXTAPOSITION OF
LOWER/UPPER LEVEL FORCING OCCURS DURING FROPA.
WIND:
DUE TO A TIGHT HEIGHT/MSLP GRADIENT AHEAD OF THE FRONT AND LOW-LEVEL
TROUGH...AN IMPRESSIVE SOUTHWESTERLY LLJ WAS PRESENT THIS MORNING ON
THE 12Z RAOBS...WITH GSO/RNK REPORTING 50 KT AT H85 AND UPSTREAM
RAOBS BNA/ILN REPORTING 65-75 KT. THE 12Z GSO SOUNDING ACTUALLY
INDICATED 50 KT SW FLOW AS LOW AS 1500 FT AGL. FCST SOUNDINGS SHOW
40-50 KT FLOW AS LOW AS 2000-3000 FT AGL ACROSS CENTRAL NC THIS
AFTERNOON. LUCKILY...WIDESPREAD MID-LEVEL CLOUD COVER MOVING INTO
THE AREA FROM THE WEST WILL LIMIT DIURNAL HEATING/MIXING AND
LOW-LEVEL WARM ADVECTION SHOULD RESULT IN AN INVERSION AOA 925 MB.
THESE FACTORS SHOULD PREVENT THE TOP OF THE MIXED LAYER FROM
EXCEEDING ~2500 FT AND HELP PREVENT THE STRONGEST LOW-LEVEL FLOW
FROM MIXING DOWN. HOWEVER...UNCERTAINTY PERSISTS...AND IT IS
POSSIBLE SOME LOCATIONS COULD SEE SUSTAINED WINDS OF 25 KT AND GUSTS
UP TO 40 KT FOR A BRIEF PERIOD THIS AFTERNOON...ESPECIALLY IN THE
EAST WHERE MORE SUNSHINE THIS MORNING WILL ALLOW FOR BETTER MIXING.
WILL CONTINUE TO HIGHLIGHT THE POTENTIAL FOR GUSTY WINDS IN THE
HWO...AND WILL ISSUE AN SPS OR SHORT-FUSED WIND ADVISORY IF BREAKS
IN CLOUD COVER OR STRONGER LOW-LEVEL FLOW THAN ANTICIPATED RESULT IN
FREQUENT WIND GUSTS APPROACHING OR EXCEEDING 40 KT.
TEMPERATURES:
WITH BREEZY SOUTHWEST FLOW AND 1000-850 MB THICKNESSES PROGGED AT
~1360 METERS...EXPECT HIGHS RANGING FROM 60-68F...COOLEST NW AND
WARMEST E/SE. OVERNIGHT...LOWS WILL DEPEND PRIMARILY ON THE TIMING
OF THE FRONTAL PASSAGE AND THE COVERAGE OF SHOWER ACTIVITY PRIOR
TO/DURING FROPA. EXPECT LOWS TO RANGE FROM THE MID/UPPER 30S TO
LOWER 40S N/NW...TO MID/UPPER 40S TO LOWER 50S S/SE. -VINCENT
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 255 PM MONDAY...
FOR WEDNESDAY/WEDNESDAY NIGHT: THE NAM IS A BIT SLOWER THAN THE GFS
TO PUSH THE FRONT AND PRECIP EAST OF THE CWA WEDNESDAY MORNING...
BUT IT HAS SUPPORT FROM THE ECMWF AND WILL LEAN TOWARD THIS SOLUTION
BY RETAINING CHANCE POPS IN THE SOUTHEAST FOR A FEW HOURS IN THE
MORNING. OTHERWISE... BRISK NW WINDS WILL BRING IN MUCH COOLER AIR
THROUGH THE DAY WITH 850 MB TEMPS FALLING NEARLY 18C FROM TUESDAY
EVENING TO WEDNESDAY EVENING. TEMPS ARE LIKELY TO RISE JUST A FEW
DEGREES FROM THE FAIRLY MILD MORNING LOWS IN MOST LOCATIONS. NET
HIGHS WILL BE 44-56... ALTHOUGH IN THE SOUTHEAST CWA THESE HIGHS
WILL OCCUR IN THE MORNING WITH STEADY OR FALLING READINGS THROUGH
THE DAY. EXPECT PARTLY TO MOSTLY SUNNY SKIES AS SURFACE HIGH
PRESSURE BUILDS IN FROM THE WEST. BUT MODELS DEPICT A STRONG
VORTICITY MAX TRACKING ACROSS NC WEDNESDAY NIGHT... AND WHILE THE
COLUMN IS LIKELY TO BE TOO STABLE AND LACKING ENOUGH DEEP MOISTURE
FOR ANY PRECIP WITH THIS FEATURE... A SHOT OF MOSTLY CLOUDY SKIES IS
LIKELY. LOWS 23-28. -GIH
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 1230 PM TUESDAY...
THE OVERALL PATTERN ACROSS THE LOWER 48 WILL CONTINUE TO FEATURE ONE
THAT IS TYPICAL OF LA NINA WINTERS. OVERALL... THE TENDENCY FOR
ABOVE NORMAL HEIGHTS AND ABOVE NORMAL TEMPERATURES WILL CONTINUE FOR
THE EASTERN STATES... WITH A DEVELOPING UPPER LOW EXPECTED OVER THE
SOUTHWESTERN U.S. NEXT WEEK. MUCH ABOVE NORMAL TEMPERATURES SHOULD
VISIT OUR REGION EARLY TO MID NEXT WEEK.
WE WILL BEGIN COLD ON THURSDAY MORNING. HOWEVER... THE PROGRESSIVE
SURFACE HIGH WILL RAPIDLY MOVE OFFSHORE EARLY IN THE DAY LEADING TO
WAA. MOST MODELS GENERALLY INDICATE INCREASING CLOUDINESS WITH THE
WAA PATTERN THURSDAY WHICH WOULD LEAD TO A SLIGHT DELAY IN THE
UPCOMING WARMING TREND LATE IN THE WEEK. THURSDAY MAY END UP BEING
MUCH LIKE THIS PAST MONDAY WHEN CLOUDS RACED IN AND KEPT
TEMPERATURES MUCH COOLER THAN THEY WOULD HAVE BEEN GIVEN THE WAA
PATTERN. A SIMILAR SET UP THURSDAY SUPPORTS HIGHS THAT WILL BE
COOLER THAN MOS GUIDANCE... LEANING TOWARD THE COOLEST MET NUMBERS
IN THE 45-50 RANGE NW TO LOWER 50S SE. NOTHING MORE THAN A FEW
SPRINKLES WILL BE FORECAST WITH THE LACK OF ANY UPPER FORCING IN THE
RETURN FLOW PATTERN.
FOR THURSDAY NIGHT AND FRIDAY... ANOTHER FAST MOVING COLD FRONT IS
FORECAST TO APPROACH THE STATE THURSDAY NIGHT AND FRIDAY MORNING
WITH LITTLE MOISTURE RETURN INDICATED. PLENTY OF MID LEVEL
CLOUDINESS AND A SW BREEZE SHOULD KEEP TEMPERATURES MILD OUT AHEAD
OF THE FRONT THURSDAY NIGHT. EXPECT MOST AREAS TO SEE LOWS REMAIN IN
THE MID TO UPPER 30S. FRIDAY... A MODEST 1025 MB SURFACE HIGH IS
EXPECTED TO BUILD IN FROM THE NORTH. THIS WILL LEAD TO CAA AND
DRYING. TEMPERATURES SHOULD BE MOSTLY IN THE 50S.
FOR FRIDAY NIGHT THROUGH THE WEEKEND... A GENERALLY REPEATING
PATTERN WITH THE HIGH EXITING TO THE EAST... A WAA RETURN FLOW
ESPECIALLY SATURDAY INTO SATURDAY NIGHT. THIS WILL BE FOLLOWED BY
ANOTHER FAST MOVING LOW PRESSURE EXPECTED TO TRACK NE FROM THE
TENNESSEE VALLEY TO THE NORTHERN MID-ATLANTIC STATES AND OFFSHORE BY
EARLY SUNDAY. THE TRAILING COLD FRONT IS FORECAST TO PUSH EAST
THROUGH NC BY 12Z SUNDAY. THE HIGHEST POP SHOULD BE LATE SAT AND SAT
NIGHT IN THE WEST... AND IN THE EAST SAT NIGHT INTO EARLY SUNDAY.
AFTER MORNING LOWS IN THE 40-45 RANGE HIGHS SHOULD SOAR INTO THE 60S
SATURDAY... THEN REMAIN IN THE UPPER 40S AND 50S SATURDAY NIGHT.
HIGHS SUNDAY SHOULD BE MOSTLY IN THE 60S WITH SOME UPPER 50S NW.
MONDAY AND TUESDAY... BUILDING HEIGHTS OVER THE SE STATES COMBINED
WITH MILD PACIFIC AIR OVER THE REGION SHOULD YIELD TEMPERATURES 20
TO 25 DEGREES ABOVE NORMAL. THIS SHOULD BE MOST NOTED AT NIGHT WHEN
LOWS MAY STAY WELL IN THE 50S (NEARLY 30 DEGREES ABOVE NORMAL)...
DEPENDING ON THE AMOUNT OF CLOUDINESS.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 645 AM TUESDAY...
MAINLY VFR CONDITIONS WILL HOLD OVER MUCH OF CENTRAL NC THROUGH
14Z... ALTHOUGH MVFR CIGS WILL LINGER AT INT/GSO DURING THIS TIME...
BEFORE LIFTING AND MIXING OUT BY 15Z. OTHERWISE... SCT-BKN CLOUDS AT
3500-5000 FT AGL AND BKN MID CLOUDS BASED ABOVE 8 KFT WILL PERSIST
THROUGH THIS MORNING AND AFTERNOON. OF CONCERN ARE THE STRONG SW
WINDS... EXPECTED TO BE SUSTAINED AT 12-20 KTS AND GUSTING TO 24-30
KTS FROM SHORTLY BEFORE DAYBREAK THIS MORNING THROUGH THE DAY...
WITH ONLY MINOR ABATEMENT THIS EVENING. WHILE LOW LEVEL WIND SHEAR
CRITERIA ARE UNLIKELY TO BE MET... SW WINDS WILL INCREASE WITH
HEIGHT (AND VEER SLIGHTLY) THROUGH THE LOWEST 5 KFT... POTENTIALLY
REACHING 50 KT AT 4-5 KFT... WHICH MAY PRODUCE MECHANICAL TURBULENCE
AND DIFFICULTY IN AIRCRAFT HANDLING. AFTER SUNSET THIS EVENING... AS
A COLD FRONT APPROACHES FROM THE NW... CIGS ARE EXPECTED TO DROP TO
MVFR WITH AREAS OF RAIN NEARING INT/GSO TOWARD 03Z-06Z... AND INTO
RDU/RWI/FAY BETWEEN 06Z-09Z LASTING UNTIL THE END OF THE TAF VALID
PERIOD (12Z). IFR CONDITIONS ARE LIKELY DURING PERIODS OF STEADY
RAIN. THE MVFR/IFR CONDITIONS WILL EXIT INT/GSO 10Z-12Z.
LOOKING BEYOND 12Z WEDNESDAY MORNING: MVFR TO BRIEFLY IFR CONDITIONS
WITH BLUSTERY SW WINDS AND AREAS OF RAIN WILL HOLD THROUGH 13Z (RDU)
TO 15Z (RWI/FAY)... WHEN COLD FRONT PASSAGE WILL DRAMATICALLY SHIFT
WINDS AROUND TO BRISK NORTHWESTERLY AS COLD AIR RUSHES IN. SKIES
WILL BE MOSTLY SUNNY WEDNESDAY AFTERNOON EXCEPT FOR PATCHES OF
CLOUDS BASED ABOVE 4 KFT AGL. VFR CONDITIONS WILL HOLD THROUGH
FRIDAY... THEN ANOTHER STORM SYSTEM WILL APPROACH FROM THE WEST
FRIDAY NIGHT... BRINGING POSSIBLE MVFR/IFR CONDITIONS LATE FRIDAY
NIGHT THROUGH SATURDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...HARTFIELD
LONG TERM...BADGETT
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1118 AM EST TUE JAN 17 2012
.SYNOPSIS...
ABOVE NORMAL TEMPERATURES AND BREEZY SOUTHWEST WINDS ARE EXPECTED
THIS AFTERNOON AHEAD OF AN APPROACHING COLD FRONT. A LINE OF SHOWERS
WILL ACCOMPANY THE COLD FRONT AS IT CROSSES THE AREA OVERNIGHT.
NEAR NORMAL TEMPERATURES AND DRY CONDITIONS ARE EXPECTED IN THE WAKE
OF THE FRONT WEDNESDAY AND THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
AS OF 1115 AM TUESDAY...
OVERVIEW:
A ROBUST NORTHERN STREAM SHORTWAVE APPROACHING THE UPPER MS RIVER
VALLEY AS OF 15Z WILL PROGRESS INTO THE GREAT LAKES BY 00Z AND INTO
NEW ENGLAND BY 12Z WED. AN ATTENDANT 1000 MB SURFACE LOW CENTERED
OVER SOUTHERN MICHIGAN AT 15Z WILL QUICKLY DEEPEN TO 990 MB AS IT
PROGRESSES TO THE LOWER GREAT LAKES BY 00Z...AND TO 985 MB AS IT
PROGRESSES TO NORTHERN MAINE BY 12Z WED. AN ASSOCIATED COLD FRONT
WILL PROGRESS EASTWARD TO THE SOUTHERN APPALACHIANS BY 00Z...AND TO
THE CAROLINA COAST BY OR SHORTLY AFTER 12Z WED. ADDITIONAL UPPER
LEVEL ENERGY UPSTREAM OVER TX AND THE LOWER MS RIVER VALLEY AT 15Z
IS PROGGED TO PROGRESS ENE INTO THE CAROLINAS/MID-ATLANTIC OVERNIGHT.
PRECIPITATION CHANCES TODAY:
CURRENT LIGHT RAIN MOVING ACROSS THE MOUNTAINS APPEARS TO BE ASSOC/W
AN UPPER LEVEL DISTURBANCE (NOTED IN RUC H3 VORTICITY). THIS FEATURE
IS PROGGED TO PROGRESS THROUGH NORTHERN VA BY 18Z AND THEN OFFSHORE
BY 21Z. ALTHOUGH IT IS POSSIBLE THAT SOME OF THIS ACTIVITY MAY CROSS
THE MOUNTAINS AND PRODUCE A FEW SPRINKLES OR AN ISOLD SHOWER...DO
NOT ANTICIPATE MUCH IN THE WAY OF MEASURABLE PRECIP...AND WILL LEAVE
A SLIGHT CHANCE OF SPRINKLES WEST OF HWY 1 THROUGH EARLY AFTERNOON.
OTHERWISE...WITH UNIDIRECTIONAL FLOW ALOFT AND IN THE LOWER LEVELS
AND LIFT GENERALLY CONFINED TO WEAK/BROAD LOW-LEVEL WARM
ADVECTION...FEEL THAT FORCING SHOULD BE INSUFFICIENT TO WARRANT
MEASURABLE PRECIPITATION CHANCES TODAY...ALTHOUGH AN ISOLD SHOWER OR
TWO CANNOT BE RULED OUT.
PRECIPITATION CHANCES TONIGHT:
CHANCES INCREASE THIS EVENING/TONIGHT FROM THE W/NW AS THE
AFOREMENTIONED FRONTAL ZONE MOVES INTO CENTRAL NC FROM THE W/NW.
EXCELLENT LOW-LEVEL CONVERGENCE IS PROGGED IN ASSOC/W THE SFC-925 MB
TROUGH...AND SOME UPPER LEVEL SUPPORT IS EXPECTED AS SUBTLE
SHORTWAVES EMBEDDED UPSTREAM (TX/LOWER MS RIVER VALLEY) IN WSW FLOW
ALOFT PROGRESS INTO THE CAROLINAS LATER THIS EVENING/TONIGHT. THE
GFS/NAM/ECMWF ALL SHOW MEASURABLE PRECIP OVER CENTRAL NC TONIGHT.
COVERAGE IS DIFFICULT TO ASCERTAIN STILL...THOUGH...AND THE HIGH RES
WRF-NMM 1KM REFLECTIVITY PRODUCT INDICATES THAT PRECIP WILL MOST
LIKELY BE IN THE FORM OF A NARROW LINE OR BROKEN LINE OF SHOWERS
THAT DEVELOPS IN VICINITY OF THE SURFACE FRONT AS IT PROGRESSES
NW-SE THROUGH THE AREA BETWEEN ROUGHLY 03-12Z. WITH THE
AFOREMENTIONED UNCERTAINTY...WILL KEEP PRECIP CHANCES NO HIGHER THAN
60-80%...WITH THE BEST CHANCES IN THE SW PIEDMONT...SANDHILLS AND SE
COASTAL PLAIN. ALTHOUGH SFC-BASED INSTABILITY IS UNLIKELY GIVEN POOR
DIURNAL TIMING AND DEWPOINTS IN THE MID 40S THE LOWER 50S AT
BEST...STEEP MID-LEVEL LAPSE RATES WILL HELP CONTRIBUTE TO THE
POTENTIAL FOR WEAK ELEVATED INSTABILITY...AND A FEW LIGHTNING
STRIKES CANNOT BE RULED OUT IF THE CORRECT JUXTAPOSITION OF
LOWER/UPPER LEVEL FORCING OCCURS DURING FROPA.
WIND:
DUE TO A TIGHT HEIGHT/MSLP GRADIENT AHEAD OF THE FRONT AND LOW-LEVEL
TROUGH...AN IMPRESSIVE SOUTHWESTERLY LLJ WAS PRESENT THIS MORNING ON
THE 12Z RAOBS...WITH GSO/RNK REPORTING 50 KT AT H85 AND UPSTREAM
RAOBS BNA/ILN REPORTING 65-75 KT. THE 12Z GSO SOUNDING ACTUALLY
INDICATED 50 KT SW FLOW AS LOW AS 1500 FT AGL. FCST SOUNDINGS SHOW
40-50 KT FLOW AS LOW AS 2000-3000 FT AGL ACROSS CENTRAL NC THIS
AFTERNOON. LUCKILY...WIDESPREAD MID-LEVEL CLOUD COVER MOVING INTO
THE AREA FROM THE WEST WILL LIMIT DIURNAL HEATING/MIXING AND
LOW-LEVEL WARM ADVECTION SHOULD RESULT IN AN INVERSION AOA 925 MB.
THESE FACTORS SHOULD PREVENT THE TOP OF THE MIXED LAYER FROM
EXCEEDING ~2500 FT AND HELP PREVENT THE STRONGEST LOW-LEVEL FLOW
FROM MIXING DOWN. HOWEVER...UNCERTAINTY PERSISTS...AND IT IS
POSSIBLE SOME LOCATIONS COULD SEE SUSTAINED WINDS OF 25 KT AND GUSTS
UP TO 40 KT FOR A BRIEF PERIOD THIS AFTERNOON...ESPECIALLY IN THE
EAST WHERE MORE SUNSHINE THIS MORNING WILL ALLOW FOR BETTER MIXING.
WILL CONTINUE TO HIGHLIGHT THE POTENTIAL FOR GUSTY WINDS IN THE
HWO...AND WILL ISSUE AN SPS OR SHORT-FUSED WIND ADVISORY IF BREAKS
IN CLOUD COVER OR STRONGER LOW-LEVEL FLOW THAN ANTICIPATED RESULT IN
FREQUENT WIND GUSTS APPROACHING OR EXCEEDING 40 KT.
TEMPERATURES:
WITH BREEZY SOUTHWEST FLOW AND 1000-850 MB THICKNESSES PROGGED AT
~1360 METERS...EXPECT HIGHS RANGING FROM 60-68F...COOLEST NW AND
WARMEST E/SE. OVERNIGHT...LOWS WILL DEPEND PRIMARILY ON THE TIMING
OF THE FRONTAL PASSAGE AND THE COVERAGE OF SHOWER ACTIVITY PRIOR
TO/DURING FROPA. EXPECT LOWS TO RANGE FROM THE MID/UPPER 30S TO
LOWER 40S N/NW...TO MID/UPPER 40S TO LOWER 50S S/SE. -VINCENT
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 255 PM MONDAY...
FOR WEDNESDAY/WEDNESDAY NIGHT: THE NAM IS A BIT SLOWER THAN THE GFS
TO PUSH THE FRONT AND PRECIP EAST OF THE CWA WEDNESDAY MORNING...
BUT IT HAS SUPPORT FROM THE ECMWF AND WILL LEAN TOWARD THIS SOLUTION
BY RETAINING CHANCE POPS IN THE SOUTHEAST FOR A FEW HOURS IN THE
MORNING. OTHERWISE... BRISK NW WINDS WILL BRING IN MUCH COOLER AIR
THROUGH THE DAY WITH 850 MB TEMPS FALLING NEARLY 18C FROM TUESDAY
EVENING TO WEDNESDAY EVENING. TEMPS ARE LIKELY TO RISE JUST A FEW
DEGREES FROM THE FAIRLY MILD MORNING LOWS IN MOST LOCATIONS. NET
HIGHS WILL BE 44-56... ALTHOUGH IN THE SOUTHEAST CWA THESE HIGHS
WILL OCCUR IN THE MORNING WITH STEADY OR FALLING READINGS THROUGH
THE DAY. EXPECT PARTLY TO MOSTLY SUNNY SKIES AS SURFACE HIGH
PRESSURE BUILDS IN FROM THE WEST. BUT MODELS DEPICT A STRONG
VORTICITY MAX TRACKING ACROSS NC WEDNESDAY NIGHT... AND WHILE THE
COLUMN IS LIKELY TO BE TOO STABLE AND LACKING ENOUGH DEEP MOISTURE
FOR ANY PRECIP WITH THIS FEATURE... A SHOT OF MOSTLY CLOUDY SKIES IS
LIKELY. LOWS 23-28. -GIH
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
AS OF 310 AM TUESDAY...
THE LATTER PART OF THE WEEK WILL FEATURE A BROAD CYCLONIC OR NEARLY
ZONAL FLOW ALOFT AS A SERIES OF LOW AMPLITUDE SHORTWAVES PASS
QUICKLY ACROSS THE NORTHERN HALF OF THE CONUS. A SURFACE HIGH
PRESSURE RIDGE WILL MOVE QUICKLY ACROSS NC ON THURSDAY...AS A LOW
PRESSURE SYSTEM SKIRTS THE GREAT LAKES AND THE TRAILING COLD FRONT
DROPPING INTO MID ATLANTIC REGION THURSDAY NIGHT. THE CANADIAN
HIGH PRESSURE BEHIND THE COLD FRONT IS FORECAST TO WEAKEN RAPIDLY
ACROSS THE MIDWEST STATES...THEN SET UP OVER NEW ENGLAND. THERE IS
SOME UNCERTAINTY AS TO HOW QUICKLY THE FRONT MAY SLIP SOUTH INTO
CENTRAL NC ON FRIDAY...IF AT ALL...WITH THE GFS BEING THE MORE
AGGRESSIVE OF THE MEDIUM RANGE MODELS. A STRONGER NORTHERN STREAM
SHORTWAVE IS THEN PROGGED TO CROSS THE MID MS VALLEY REGION FRIDAY
NIGHT AND ENHANCE SOUTHERLY RETURN FLOW AND SHOWER ACTIVITY ALONG
THE FRONTAL ZONE ON SATURDAY. WILL MAINTAIN THE CURRENT 40 PERCENT
POP ON SATURDAY UNTIL THE GFS AND ECMWF SHOW BETTER AGREEMENT ON THE
POSITION AND TIMING PRECIP AND AND A POSSIBLE COLD FRONT
SATURDAY/SATURDAY NIGHT. MODELS THEN DIVERGE MORE SIGNIFICANTLY FROM
SUNDAY ONWARD AS CUTOFF ENERGY OVER THE CALIFORNIA BAJA INTERACTS
WITH MORE SIGNIFICANT ENERGY MAKING LANDFALL ALONG THE NORTHERN
CALIFORNIA COAST. AT THAT POINT...THERE IS LITTLE CONFIDENCE IN
MODEL FORECASTS...BUT THE NEXT CHANCE FOR PRECIP SHOULD HOLD OFF
UNTIL AFTER MONDAY AS THE FLOW BEGINS TO AMPLIFY A BIT MORE.
TEMPS THROUGH THE WEEKEND SHOULD SHOW A SLOW MODERATION FROM MID
AND UPPER 40S THURSDAY TOWARD THE UPPER 50S TO AROUND 60 ON
SATURDAY. DESPITE 1000-850MB THICKNESSES FORECAST TO PEAK NEAR
1365M BY THE END OF THE WEEKEND...WILL KEEP HIGHS BELOW THEIR FULL
POTENTIAL SINCE THEIR WILL LIKELY BE PERIODS OF WIDESPREAD CLOUD
COVER...WITH HIGHS CREEPING UP THROUGH THE 60S SUNDAY AND MONDAY.
&&
.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
AS OF 645 AM TUESDAY...
MAINLY VFR CONDITIONS WILL HOLD OVER MUCH OF CENTRAL NC THROUGH
14Z... ALTHOUGH MVFR CIGS WILL LINGER AT INT/GSO DURING THIS TIME...
BEFORE LIFTING AND MIXING OUT BY 15Z. OTHERWISE... SCT-BKN CLOUDS AT
3500-5000 FT AGL AND BKN MID CLOUDS BASED ABOVE 8 KFT WILL PERSIST
THROUGH THIS MORNING AND AFTERNOON. OF CONCERN ARE THE STRONG SW
WINDS... EXPECTED TO BE SUSTAINED AT 12-20 KTS AND GUSTING TO 24-30
KTS FROM SHORTLY BEFORE DAYBREAK THIS MORNING THROUGH THE DAY...
WITH ONLY MINOR ABATEMENT THIS EVENING. WHILE LOW LEVEL WIND SHEAR
CRITERIA ARE UNLIKELY TO BE MET... SW WINDS WILL INCREASE WITH
HEIGHT (AND VEER SLIGHTLY) THROUGH THE LOWEST 5 KFT... POTENTIALLY
REACHING 50 KT AT 4-5 KFT... WHICH MAY PRODUCE MECHANICAL TURBULENCE
AND DIFFICULTY IN AIRCRAFT HANDLING. AFTER SUNSET THIS EVENING... AS
A COLD FRONT APPROACHES FROM THE NW... CIGS ARE EXPECTED TO DROP TO
MVFR WITH AREAS OF RAIN NEARING INT/GSO TOWARD 03Z-06Z... AND INTO
RDU/RWI/FAY BETWEEN 06Z-09Z LASTING UNTIL THE END OF THE TAF VALID
PERIOD (12Z). IFR CONDITIONS ARE LIKELY DURING PERIODS OF STEADY
RAIN. THE MVFR/IFR CONDITIONS WILL EXIT INT/GSO 10Z-12Z.
LOOKING BEYOND 12Z WEDNESDAY MORNING: MVFR TO BRIEFLY IFR CONDITIONS
WITH BLUSTERY SW WINDS AND AREAS OF RAIN WILL HOLD THROUGH 13Z (RDU)
TO 15Z (RWI/FAY)... WHEN COLD FRONT PASSAGE WILL DRAMATICALLY SHIFT
WINDS AROUND TO BRISK NORTHWESTERLY AS COLD AIR RUSHES IN. SKIES
WILL BE MOSTLY SUNNY WEDNESDAY AFTERNOON EXCEPT FOR PATCHES OF
CLOUDS BASED ABOVE 4 KFT AGL. VFR CONDITIONS WILL HOLD THROUGH
FRIDAY... THEN ANOTHER STORM SYSTEM WILL APPROACH FROM THE WEST
FRIDAY NIGHT... BRINGING POSSIBLE MVFR/IFR CONDITIONS LATE FRIDAY
NIGHT THROUGH SATURDAY. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...VINCENT
NEAR TERM...VINCENT
SHORT TERM...HARTFIELD
LONG TERM...SMITH
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
448 PM EST TUE JAN 17 2012
.SYNOPSIS...
LOW PRESSURE OVER SOUTHERN LAKE HURON THIS AFTERNOON WILL STRENGTHEN
AS IT LIFTS NORTHEAST ACROSS THE LOWER GREAT LAKES AND DOWN
THE SAINT LAWRENCE RIVER VALLEY LATE TODAY AND TONIGHT. A SHARP COLD
FRONT TRAILING SOUTH FROM THIS LOW WILL SWEEP ACROSS THE
COMMONWEALTH EARLY TONIGHT...FOLLOWED BY A SURGE OF COLDER AIR AND
STRONG GUSTY WINDS. HIGH PRESSURE WILL MOVE INTO THE REGION LATER
WEDNESDAY INTO EARLY THURSDAY. A PAIR OF UPPER AIR DISTURBANCES AND
WEAK SURFACE LOWS SHOULD BRING A FEW PERIODS OF MAINLY LIGHT SNOW TO
THE REGION THURSDAY AFTERNOON AND NIGHT...AND AGAIN LATE FRIDAY
NIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
EXTREMELY STRONG 60-70KT 925-850 SWRLY LLJ WAS LIFTING NE ACROSS WRN
PENN AHEAD OF A DEEPENING AREA OF LOW PRESSURE CURRENTLY SITUATED
ACROSS THE SOUTHERN TIP OF LAKE HURON.
MOVED UP THE WIND ADVISORY BY 5 HOURS TO ACCOUNT FOR THIS STRONG
WIND IMPACT TO THE RIDGE TOPS OF THE LAURELS THIS AFTERNOON...AND
MAINTAINED THE PREVIOUS WIND ADVISORY FOR THE REST OF THE WESTERN
MTNS THIS EVENING INTO EARLY WEDNESDAY MORNING IN THE WAKE OF A
STRONG COLD FRONT.
FAST MOVING SHOWERS OF RAIN /ENE AT 60 KTS/ AND EVEN A FEW BREAKS IN
THE LAYERED CLOUD DECK WILL OCCUR IN THE STRONG/DEEP WSWRLY FLOW
AHEAD OF THE SFC COLD FRONT. THIS FRONT EXTENDED FROM JUST EAST OF
TOLEDO OHIO...TO WILMINGTON OHIO AT 1930Z AND WAS MOVING QUICKLY TO
THE EAST AT 40KT.
LINEAR EXTRAPOLATION BRINGS THE FRONT INTO WARREN COUNTY BETWEEN
23-00Z...AND AROUND 01Z ALONG THE LENGTH OF ROUTE 219 IN WRN PENN.
THE CFRONT WITH A LIKELY BAND OF GUSTY MDT TO BRIEFLY HEAVY RAIN
SHOWERS WILL REACH THE LOWER SUSQ VALLEY AROUND 03-04Z.
ELEVATED...925-850 MB LIFTED INDICES VIA THE RUC DROP TO NEAR...OR
SLIGHTLY BELOW ZERO ACROSS FAR SCENT PENN AND LOWER SUSQ VALLEY LATE
TODAY AND THIS EVENING. THIS MARGINAL INSTABILITY COULD SUPPORT A
FEW RUMBLES OF THUNDER ALONG THE COLD FRONTAL BOUNDARY.
VERY MILD TEMPS IN THE 40S...TO LOWER AND MID 50S IN THE SOUTH WILL
PLUMMET IN THE WAKE OF THE FRONT. THE MUCH COLDER TEMPS IN THE TEENS
/NW/...AND 20S SE WED MORNING WILL COMBINE WITH THE STRONG WESTERLY
WINDS TO BRING WIND CHILLS IN THE SINGLE DIGITS /NW/ TO TEENS /SE/.
ADDITIONAL RAINFALL LATE THIS AFTERNOON AND TONIGHT WILL AVERAGE
0.10-0.25 OF AN INCH.
RAIN SHOWERS WILL MIX WITH THEN CHANGE TO FREQUENT SHSN ACROSS THE
NW MTNS LATE THIS EVENING...WITH ACCUMULATING LES BANDS PUSHING
GRADUALLY INLAND FROM THE ERIE LAKE SHORE BY SHORTLY AFTER
MIDNIGHT.
THE BASE OF THE SUBSIDENCE INVERSION RISES TO 7-8 KFT AGL LATE
TONIGHT AND EARLY WEDNESDAY...AND A DECENT CROSS-HAIR SIGNATURE OF
UVVEL WITH THE PRIME THERMAL RIBBON FOR DENDRITIC GROWTH OCCURS
BETWEEN ABOUT 09Z AND 15Z WED...AND THAT/S WHEN THE MOST PERSISTENT
LES IS EXPECTED. RECENTLY ISSUED A LES ADVISORY FOR WARREN CTY
/MAINLY THE NW 1/3 OF THE CTY/ FROM 1 AM WED TO 4 PM WED FOR A
GENERAL 3-5 INCHES OF WIND WHIPPED SNOW AND OCNL VERY POOR VSBYS
VARIABLE AMOUNTS OF CLOUDS AND WINDY CONDITIONS WITH JUST SOME
FLURRIES WILL AFFECT THE CENTRAL RIDGE AND VALLEY REGION DURING THE
DAY WED. TEMP CURVE WILL BE VERY FLAT WEDNESDAY UNDER STRONG LLVL
COLD ADVECTION. MAX TEMPS AROUND 20F IN THE NW...AND LOWER TO MID
30S IN THE SE WILL BE JUST NEAR...TO A FEW DEG F BELOW NORMAL.
WINDS WILL RELAX BY WED AFTN AS HIGH PRES BUILDS TAKES UP BRIEF
RESIDENCE OVR PA. ANY LINGERING LAKE EFFECT OR UPSLOPE SNOW SHOWERS
SHOULD ALSO TAPER OFF THROUGHOUT THE AFTN.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
THE N-S RIDGE AXIS WILL PROVIDE A RESPITE FROM
PRECIPITATION INTO THURSDAY...WITH THE SHIFTING FLOW TO THE
NORTHWEST BY MIDDAY THURSDAY PROVIDING ENOUGH MOISTURE AND COLD
AIR TO BRING SCATTERED SNOW SHOWERS INTO THE NW MTNS...ESPECIALLY
WITH -13C AT 850MB. EXPECT LIGHT ACCUMULATIONS...WITH THE HEAVIEST
AMTS IN THE HIGHER TERRAIN. HIGHS WILL AVG A FEW TO SEVERAL DEGS
BELOW NORMAL WITH SEASONABLY COLD OVERNIGHT READINGS IN THE TEENS
AND 20S. SOME OF THE USUALLY COLD RURAL VLYS IN THE NRN TIER COULD
TOUCH THE SINGLE DIGITS UNDER IDEAL RADIATIONAL COOLING.
THIS CLIPPER TYPE LOW WILL MOVE QUICKLY THROUGH THURSDAY NIGHT. THE
STEADY MOVEMENT OF THIS SYSTEM SHOULD LIMIT AMTS TO BLW ADVY
CRITERIA. A REINFORCING SHOT OF COLD AIR WILL ARRIVE BEHIND THIS
SYSTEM THURSDAY NIGHT INTO FRIDAY.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
A WEAK RIDGE BUILDING OVER THE AREA FRIDAY SHOULD STIFLE ANY
PRECIPITATION...ESPECIALLY WITH THE WEAK FLOW...THOUGH EARLY IN
THE PERIOD...BEFORE 12Z...THERE COULD BE STRONG ENOUGH FLOW AND COLD
AIR THAT COULD ALLOW FOR A PERIOD OF LAKE EFFECT SNOW. TEMPERATURES
WILL BE COLD INTO SATURDAY. THE MODELS STILL COMPLETELY DISAGREE
ON THE TIMING OF THE SYSTEM PROPAGATING THROUGH THE REGION THIS
WEEKEND. THE GFS MOVES IT THROUGH MORE RAPIDLY WHERE THE EC
DEEPENS THE STRONG AND TAKES IT FURTHER TO THE SOUTH. HAVE TENDED
TOWARD THE EC..WITH MOS GUIDANCE FOR TEMPS...AS WARM AIR DOESN`T
GET HERE UNTIL SUNDAY. THE WARM AIR ADVECTION ON SUNDAY SHOULD
SEE WARMER HIGHS IN THE 40S. BASED ON THE CONSENSUS AND RECENT
TRENDS...HAVE BEST PRECIP CHANCES BY MIDDAY SATURDAY...WITH A
POSSIBILITY OF A RAIN SNOW MIX. COLDER TEMPERATURES SUGGEST MOST
ARES WILL HAVE SNOW...HOWEVER THE LOWER SUSQ REGION IS STILL UP IN
THE AIR DEPENDING ON ANY WARM AIR ALOFT. AS SUCH HAVE LEFT RAIN
AND SNOW IN THE WORDING. MAIN PRECIP CHANCES ON SUNDAY ARE IN THE
NW MTNS AND THE HIGHER ELEVATIONS. ANOTHER TROUGH COULD MOVE
THROUGH THE AREA MONDAY INTO TUESDAY....THIS LOOKS TO BE ANOTHER
FAST MOVING SYSTEM BUT WITH TIMING IN QUESTION HAVE LEFT ONLY
SLIGHT CHANCE POPS.
&&
.AVIATION /22Z TUESDAY THROUGH SUNDAY/...
MINOR UPDATE TO 21Z TAF PACKAGE...MOST AREAS IN WARM AIR AND
VFR NOW. WIND SHIFT AND COLD AIR WELL TO THE WEST AT THIS POINT...
SO I SLOWED DOWN WIND SHIFT...AND ALSO MIX OF RAIN AND SNOW
FOR BFD. LINE OF SHOWERS RACING EASTWARD ACROSS NORTHERN OH
WILL BE NEAR BFD SOON.
EARLIER DISCUSSION BELOW.
AN APPROACHING LOW PRESSURE SYSTEM WILL BRING STRONG SWRLY FLOW
ALOFT...RESULTING IN CONTINUE LLWS ACROSS MOST OF CENTRAL PA THRU
THIS EVENING.
A FEW ADDITIONAL PERIODS OF RAIN SHOWERS ACCOMPANIED BY WIDESPREAD
MVFR CIGS AND MAINLY VFR VSBYS WILL OCCUR FOR THE REST OF TODAY.
AS LOW PRES CENTER TRACKS WEST OF THE STATE. LIFTING CIGS/IMPROVING
VSBYS WILL BE LIKELY ACROSS SOUTHERN PA LATE THIS AFTN/EVENING...
AS A WARM FRONT LIFTS NORTH OF THE MIDDLE SUSQ VALLEY.
A STRONG COLD FRONT WILL PUSH THROUGH THE REGION THIS EVENING
ACCOMPANIED BY A NARROW BAND OF HEAVY SHRA /AND POSSIBLY EVEN A
RUMBLE OF THUNDER/ FOLLOWED BY WESTERLY WINDS GUSTING BETWEEN 30 AND
35KTS ACROSS MOST OF THE REGION TONIGHT AND EARLY WEDNESDAY. GUSTS
COULD BE BETWEEN 45-50 MPH ACROSS THE NW MTNS AND LAUREL HIGHLANDS.
OUTLOOK...
WED...WESTERLY WINDS - GUSTING TO 35-40KT EARLY ACROSS THE WRN MTNS.
LAKE EFFECT SNOW SHOWERS NEAR..AND TO THE WEST OF KBFD WITH OCNL IFR
CIGS AND VSBYS MAINLY IN THE MORNING. NO SIG WX EXPECTED ELSEWHERE.
THU...SHSN OR EVEN A PERIOD OF STEADY LIGHT SNOW/REDUCED VSBYS
POSS...MAINLY W MTNS.
FRI...NO SIG WX EXPECTED.
SAT...PERIODS OF LGT SNOW NW AND MIXED PRECIP SE.
SUN...NO SIGNIF WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY UNTIL 6 AM EST WEDNESDAY FOR PAZ004>006-010-011.
LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 4 PM EST WEDNESDAY FOR
PAZ004.
WIND ADVISORY UNTIL 6 AM EST WEDNESDAY FOR PAZ017-024-033.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...CERU/STEINBUGL
LONG TERM...CERU
AVIATION...LAMBERT/MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
401 PM EST TUE JAN 17 2012
.SYNOPSIS...
LOW PRESSURE OVER SOUTHERN LAKE HURON THIS AFTERNOON WILL STRENGTHEN
AS IT LIFTS NORTHEAST ACROSS THE LOWER GREAT LAKES AND DOWN
THE SAINT LAWRENCE RIVER VALLEY LATE TODAY AND TONIGHT. A SHARP COLD
FRONT TRAILING SOUTH FROM THIS LOW WILL SWEEP ACROSS THE
COMMONWEALTH EARLY TONIGHT...FOLLOWED BY A SURGE OF COLDER AIR AND
STRONG GUSTY WINDS. HIGH PRESSURE WILL MOVE INTO THE REGION LATER
WEDNESDAY INTO EARLY THURSDAY. A PAIR OF UPPER AIR DISTURBANCES AND
WEAK SURFACE LOWS SHOULD BRING A FEW PERIODS OF MAINLY LIGHT SNOW TO
THE REGION THURSDAY AFTERNOON AND NIGHT...AND AGAIN LATE FRIDAY
NIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
EXTREMELY STRONG 60-70KT 925-850 SWRLY LLJ WAS LIFTING NE ACROSS WRN
PENN AHEAD OF A DEEPENING AREA OF LOW PRESSURE CURRENTLY SITUATED
ACROSS THE SOUTHERN TIP OF LAKE HURON.
MOVED UP THE WIND ADVISORY BY 5 HOURS TO ACCOUNT FOR THIS STRONG
WIND IMPACT TO THE RIDGE TOPS OF THE LAURELS THIS AFTERNOON...AND
MAINTAINED THE PREVIOUS WIND ADVISORY FOR THE REST OF THE WESTERN
MTNS THIS EVENING INTO EARLY WEDNESDAY MORNING IN THE WAKE OF A
STRONG COLD FRONT.
FAST MOVING SHOWERS OF RAIN /ENE AT 60 KTS/ AND EVEN A FEW BREAKS IN
THE LAYERED CLOUD DECK WILL OCCUR IN THE STRONG/DEEP WSWRLY FLOW
AHEAD OF THE SFC COLD FRONT. THIS FRONT EXTENDED FROM JUST EAST OF
TOLEDO OHIO...TO WILMINGTON OHIO AT 1930Z AND WAS MOVING QUICKLY TO
THE EAST AT 40KT.
LINEAR EXTRAPOLATION BRINGS THE FRONT INTO WARREN COUNTY BETWEEN
23-00Z...AND AROUND 01Z ALONG THE LENGTH OF ROUTE 219 IN WRN PENN.
THE CFRONT WITH A LIKELY BAND OF GUSTY MDT TO BRIEFLY HEAVY RAIN
SHOWERS WILL REACH THE LOWER SUSQ VALLEY AROUND 03-04Z.
ELEVATED...925-850 MB LIFTED INDICES VIA THE RUC DROP TO NEAR...OR
SLIGHTLY BELOW ZERO ACROSS FAR SCENT PENN AND LOWER SUSQ VALLEY LATE
TODAY AND THIS EVENING. THIS MARGINAL INSTABILITY COULD SUPPORT A
FEW RUMBLES OF THUNDER ALONG THE COLD FRONTAL BOUNDARY.
VERY MILD TEMPS IN THE 40S...TO LOWER AND MID 50S IN THE SOUTH WILL
PLUMMET IN THE WAKE OF THE FRONT. THE MUCH COLDER TEMPS IN THE TEENS
/NW/...AND 20S SE WED MORNING WILL COMBINE WITH THE STRONG WESTERLY
WINDS TO BRING WIND CHILLS IN THE SINGLE DIGITS /NW/ TO TEENS /SE/.
ADDITIONAL RAINFALL LATE THIS AFTERNOON AND TONIGHT WILL AVERAGE
0.10-0.25 OF AN INCH.
RAIN SHOWERS WILL MIX WITH THEN CHANGE TO FREQUENT SHSN ACROSS THE
NW MTNS LATE THIS EVENING...WITH ACCUMULATING LES BANDS PUSHING
GRADUALLY INLAND FROM THE ERIE LAKE SHORE BY SHORTLY AFTER
MIDNIGHT.
THE BASE OF THE SUBSIDENCE INVERSION RISES TO 7-8 KFT AGL LATE
TONIGHT AND EARLY WEDNESDAY...AND A DECENT CROSS-HAIR SIGNATURE OF
UVVEL WITH THE PRIME THERMAL RIBBON FOR DENDRITIC GROWTH OCCURS
BETWEEN ABOUT 09Z AND 15Z WED...AND THAT/S WHEN THE MOST PERSISTENT
LES IS EXPECTED. RECENTLY ISSUED A LES ADVISORY FOR WARREN CTY
/MAINLY THE NW 1/3 OF THE CTY/ FROM 1 AM WED TO 4 PM WED FOR A
GENERAL 3-5 INCHES OF WIND WHIPPED SNOW AND OCNL VERY POOR VSBYS
VARIABLE AMOUNTS OF CLOUDS AND WINDY CONDITIONS WITH JUST SOME
FLURRIES WILL AFFECT THE CENTRAL RIDGE AND VALLEY REGION DURING THE
DAY WED. TEMP CURVE WILL BE VERY FLAT WEDNESDAY UNDER STRONG LLVL
COLD ADVECTION. MAX TEMPS AROUND 20F IN THE NW...AND LOWER TO MID
30S IN THE SE WILL BE JUST NEAR...TO A FEW DEG F BELOW NORMAL.
WINDS WILL RELAX BY WED AFTN AS HIGH PRES BUILDS TAKES UP BRIEF
RESIDENCE OVR PA. ANY LINGERING LAKE EFFECT OR UPSLOPE SNOW SHOWERS
SHOULD ALSO TAPER OFF THROUGHOUT THE AFTN.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
THE N-S RIDGE AXIS WILL PROVIDE A RESPITE FROM
PRECIPITATION INTO THURSDAY...WITH THE SHIFTING FLOW TO THE
NORTHWEST BY MIDDAY THURSDAY PROVIDING ENOUGH MOISTURE AND COLD
AIR TO BRING SCATTERED SNOW SHOWERS INTO THE NW MTNS...ESPECIALLY
WITH -13C AT 850MB. EXPECT LIGHT ACCUMULATIONS...WITH THE HEAVIEST
AMTS IN THE HIGHER TERRAIN. HIGHS WILL AVG A FEW TO SEVERAL DEGS
BELOW NORMAL WITH SEASONABLY COLD OVERNIGHT READINGS IN THE TEENS
AND 20S. SOME OF THE USUALLY COLD RURAL VLYS IN THE NRN TIER COULD
TOUCH THE SINGLE DIGITS UNDER IDEAL RADIATIONAL COOLING.
THIS CLIPPER TYPE LOW WILL MOVE QUICKLY THROUGH THURSDAY NIGHT. THE
STEADY MOVEMENT OF THIS SYSTEM SHOULD LIMIT AMTS TO BLW ADVY
CRITERIA. A REINFORCING SHOT OF COLD AIR WILL ARRIVE BEHIND THIS
SYSTEM THURSDAY NIGHT INTO FRIDAY.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
A WEAK RIDGE BUILDING OVER THE AREA FRIDAY SHOULD STIFLE ANY
PRECIPITATION...ESPECIALLY WITH THE WEAK FLOW...THOUGH EARLY IN
THE PERIOD...BEFORE 12Z...THERE COULD BE STRONG ENOUGH FLOW AND COLD
AIR THAT COULD ALLOW FOR A PERIOD OF LAKE EFFECT SNOW. TEMPERATURES
WILL BE COLD INTO SATURDAY. THE MODELS STILL COMPLETELY DISAGREE
ON THE TIMING OF THE SYSTEM PROPAGATING THROUGH THE REGION THIS
WEEKEND. THE GFS MOVES IT THROUGH MORE RAPIDLY WHERE THE EC
DEEPENS THE STRONG AND TAKES IT FURTHER TO THE SOUTH. HAVE TENDED
TOWARD THE EC..WITH MOS GUIDANCE FOR TEMPS...AS WARM AIR DOESN`T
GET HERE UNTIL SUNDAY. THE WARM AIR ADVECTION ON SUNDAY SHOULD
SEE WARMER HIGHS IN THE 40S. BASED ON THE CONSENSUS AND RECENT
TRENDS...HAVE BEST PRECIP CHANCES BY MIDDAY SATURDAY...WITH A
POSSIBILITY OF A RAIN SNOW MIX. COLDER TEMPERATURES SUGGEST MOST
ARES WILL HAVE SNOW...HOWEVER THE LOWER SUSQ REGION IS STILL UP IN
THE AIR DEPENDING ON ANY WARM AIR ALOFT. AS SUCH HAVE LEFT RAIN
AND SNOW IN THE WORDING. MAIN PRECIP CHANCES ON SUNDAY ARE IN THE
NW MTNS AND THE HIGHER ELEVATIONS. ANOTHER TROUGH COULD MOVE
THROUGH THE AREA MONDAY INTO TUESDAY....THIS LOOKS TO BE ANOTHER
FAST MOVING SYSTEM BUT WITH TIMING IN QUESTION HAVE LEFT ONLY
SLIGHT CHANCE POPS.
&&
.AVIATION /21Z TUESDAY THROUGH SUNDAY/...
AN APPROACHING LOW PRESSURE SYSTEM WILL BRING STRONG SWRLY FLOW
ALOFT...RESULTING IN CONTINUE LLWS ACROSS MOST OF CENTRAL PA THRU
THIS EVENING.
A FEW ADDITIONAL PERIODS OF RAIN SHOWERS ACCOMPANIED BY WIDESPREAD
MVFR CIGS AND MAINLY VFR VSBYS WILL OCCUR FOR THE REST OF TODAY.
AS LOW PRES CENTER TRACKS WEST OF THE STATE. LIFTING CIGS/IMPROVING
VSBYS WILL BE LIKELY ACROSS SOUTHERN PA LATE THIS AFTN/EVENING...
AS A WARM FRONT LIFTS NORTH OF THE MIDDLE SUSQ VALLEY.
A STRONG COLD FRONT WILL PUSH THROUGH THE REGION THIS EVENING
ACCOMPANIED BY A NARROW BAND OF HEAVY SHRA /AND POSSIBLY EVEN A
RUMBLE OF THUNDER/ FOLLOWED BY WESTERLY WINDS GUSTING BETWEEN 30 AND
35KTS ACROSS MOST OF THE REGION TONIGHT AND EARLY WEDNESDAY. GUSTS
COULD BE BETWEEN 45-50 MPH ACROSS THE NW MTNS AND LAUREL HIGHLANDS.
OUTLOOK...
WED...WESTERLY WINDS - GUSTING TO 35-40KT EARLY ACROSS THE WRN MTNS.
LAKE EFFECT SNOW SHOWERS NEAR..AND TO THE WEST OF KBFD WITH OCNL IFR
CIGS AND VSBYS MAINLY IN THE MORNING. NO SIG WX EXPECTED ELSEWHERE.
THU...SHSN OR EVEN A PERIOD OF STEADY LIGHT SNOW/REDUCED VSBYS
POSS...MAINLY W MTNS.
FRI...NO SIG WX EXPECTED.
SAT...PERIODS OF LGT SNOW NW AND MIXED PRECIP SE.
SUN...NO SIGNIF WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST WEDNESDAY FOR
PAZ004>006-010-011.
LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 4 PM EST WEDNESDAY FOR
PAZ004.
WIND ADVISORY UNTIL 6 AM EST WEDNESDAY FOR PAZ017-024-033.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...CERU/STEINBUGL
LONG TERM...CERU
AVIATION...LAMBERT
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
315 PM EST TUE JAN 17 2012
.SYNOPSIS...
LOW PRESSURE OVER SOUTHERN LAKE HURON THIS AFTERNOON WILL STRENGTHEN
AS IT LIFTS NORTHEAST ACROSS THE LOWER GREAT LAKES AND DOWN
THE SAINT LAWRENCE RIVER VALLEY LATE TODAY AND TONIGHT. A SHARP COLD
FRONT TRAILING SOUTH FROM THIS LOW WILL SWEEP ACROSS THE
COMMONWEALTH EARLY TONIGHT...FOLLOWED BY A SURGE OF COLDER AIR AND
STRONG GUSTY WINDS. HIGH PRESSURE WILL MOVE INTO THE REGION LATER
WEDNESDAY INTO EARLY THURSDAY. A PAIR OF UPPER AIR DISTURBANCES AND
WEAK SURFACE LOWS SHOULD BRING A FEW PERIODS OF MAINLY LIGHT SNOW TO
THE REGION THURSDAY AFTERNOON AND NIGHT...AND AGAIN LATE FRIDAY
NIGHT INTO SATURDAY.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
EXTREMELY STRONG 60-70KT 925-850 SWRLY LLJ WAS LIFTING NE ACROSS WRN
PENN AHEAD OF A DEEPENING AREA OF LOW PRESSURE CURRENTLY SITUATED
ACROSS THE SOUTHERN TIP OF LAKE HURON.
MOVED UP THE WIND ADVISORY BY 5 HOURS TO ACCOUNT FOR THIS STRONG
WIND IMPACT TO THE RIDGE TOPS OF THE LAURELS THIS AFTERNOON...AND
MAINTAINED THE PREVIOUS WIND ADVISORY FOR THE REST OF THE WESTERN
MTNS THIS EVENING INTO EARLY WEDNESDAY MORNING IN THE WAKE OF A
STRONG COLD FRONT.
FAST MOVING SHOWERS OF RAIN /ENE AT 60 KTS/ AND EVEN A FEW BREAKS IN
THE LAYERED CLOUD DECK WILL OCCUR IN THE STRONG/DEEP WSWRLY FLOW
AHEAD OF THE SFC COLD FRONT. THIS FRONT EXTENDED FROM JUST EAST OF
TOLEDO OHIO...TO WILMINGTON OHIO AT 1930Z AND WAS MOVING QUICKLY TO
THE EAST AT 40KT.
LINEAR EXTRAPOLATION BRINGS THE FRONT INTO WARREN COUNTY BETWEEN
23-00Z...AND AROUND 01Z ALONG THE LENGTH OF ROUTE 219 IN WRN PENN.
THE CFRONT WITH A LIKELY BAND OF GUSTY MDT TO BRIEFLY HEAVY RAIN
SHOWERS WILL REACH THE LOWER SUSQ VALLEY AROUND 03-04Z.
ELEVATED...925-850 MB LIFTED INDICES VIA THE RUC DROP TO NEAR...OR
SLIGHTLY BELOW ZERO ACROSS FAR SCENT PENN AND LOWER SUSQ VALLEY LATE
TODAY AND THIS EVENING. THIS MARGINAL INSTABILITY COULD SUPPORT A
FEW RUMBLES OF THUNDER ALONG THE COLD FRONTAL BOUNDARY.
VERY MILD TEMPS IN THE 40S...TO LOWER AND MID 50S IN THE SOUTH WILL
PLUMMET IN THE WAKE OF THE FRONT. THE MUCH COLDER TEMPS IN THE TEENS
/NW/...AND 20S SE WED MORNING WILL COMBINE WITH THE STRONG WESTERLY
WINDS TO BRING WIND CHILLS IN THE SINGLE DIGITS /NW/ TO TEENS /SE/.
ADDITIONAL RAINFALL LATE THIS AFTERNOON AND TONIGHT WILL AVERAGE
0.10-0.25 OF AN INCH.
RAIN SHOWERS WILL MIX WITH THEN CHANGE TO FREQUENT SHSN ACROSS THE
NW MTNS LATE THIS EVENING...WITH ACCUMULATING LES BANDS PUSHING
GRADUALLY INLAND FROM THE ERIE LAKE SHORE BY SHORTLY AFTER
MIDNIGHT.
THE BASE OF THE SUBSIDENCE INVERSION RISES TO 7-8 KFT AGL LATE
TONIGHT AND EARLY WEDNESDAY...AND A DECENT CROSS-HAIR SIGNATURE OF
UVVEL WITH THE PRIME THERMAL RIBBON FOR DENDRITIC GROWTH OCCURS
BETWEEN ABOUT 09Z AND 15Z WED...AND THAT/S WHEN THE MOST PERSISTENT
LES IS EXPECTED. RECENTLY ISSUED A LES ADVISORY FOR WARREN CTY
/MAINLY THE NW 1/3 OF THE CTY/ FROM 1 AM WED TO 4 PM WED FOR A
GENERAL 3-5 INCHES OF WIND WHIPPED SNOW AND OCNL VERY POOR VSBYS
VARIABLE AMOUNTS OF CLOUDS AND WINDY CONDITIONS WITH JUST SOME
FLURRIES WILL AFFECT THE CENTRAL RIDGE AND VALLEY REGION DURING THE
DAY WED. TEMP CURVE WILL BE VERY FLAT WEDNESDAY UNDER STRONG LLVL
COLD ADVECTION. MAX TEMPS AROUND 20F IN THE NW...AND LOWER TO MID
30S IN THE SE WILL BE JUST NEAR...TO A FEW DEG F BELOW NORMAL.
WINDS WILL RELAX BY WED AFTN AS HIGH PRES BUILDS TAKES UP BRIEF
RESIDENCE OVR PA. ANY LINGERING LAKE EFFECT OR UPSLOPE SNOW SHOWERS
SHOULD ALSO TAPER OFF THROUGHOUT THE AFTN.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
THE N-S RIDGE AXIS WILL PROVIDE A PD OF MAINLY DRY AND TRANQUIL
CONDS THRU WED NGT BEFORE THE NEXT SYS APPROACHES BY EARLY THURS.
HIGHS WILL AVG A FEW TO SEVERAL DEGS BELOW NORMAL WITH SEASONABLY
COLD OVERNIGHT READINGS IN THE TEENS AND 20S. SOME OF THE USUALLY
COLD RURAL VLYS IN THE NRN TIER COULD TOUCH THE SINGLE DIGITS UNDER
IDEAL RADIATIONAL COOLING.
A CLIPPER TYPE LOW WILL DROP THRU THE GRT LKS ON THURS. MDLS SHOW
A BAND OF LGT SNOW DEVELOPING IN THE PRE-FRONTAL WARM ADVN PTRN.
THE STEADY MVMT OF THIS SYS SHOULD LIMIT AMTS TO BLW ADVY
CRITERIA. A REINFORCING SHOT OF COLD AIR WILL ARRIVE BEHIND THIS
SYS FOR THURS NGT INTO FRI. HIGH PRES BRIEFLY RETURNS TO THE AREA
BY THE END OF THE PD.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
COLD AIR WITH PERIODS OF LAKE EFFECT SNOW WILL CONTINUE THROUGH
FRIDAY. TEMPERATURES WILL BE COLD THROUGH FRIDAY...ESPECIALLY AS A
FINGER OF THE JET PROTRUDES THROUGH THE EASTERN GREAT LAKES ON
FRIDAY. WITH WARM AIR ADVECTION NEXT WEEKEND SHOULD SEE WARMER
TEMPERATURES SATURDAY AND SUNDAY. THOUGH THE CURRENT LONG RANGE
MODELS HAVE A WEAK TROUGH PROPAGATING THROUGH...WITH THE EC SHOWING
SLIGHTLY MORE AMPLITUDE...A GREATER NEGATIVE TILT AND SLOWER
PROGRESSION. GFS MOVES THE SYSTEM THROUGH EARLY SATURDAY. THE EC
BRINGING THE SYSTEM THROUGH LATE SATURDAY...EARLY SUNDAY. HOWEVER
THE DICHOTOMY OF THE MODELS REMAINS THAT BY MID SUNDAY THEY ARE
ALMOST 180 DEGREES OUT OF EACH OTHER. BASED ON THE CONSENSUS AND
RECENT TRENDS...HAVE BEST PRECIP CHANCES BY MIDDAY SATURDAY...WITH A
POSSIBILITY OF A RAIN SNOW MIX. HAVE BROUGHT UP PRECIP CHANCES ON
SUNDAY SLIGHTLY BUT MAINLY IN THE HIGHER ELEVATIONS. MAINLY DRY
CONDITIONS ELSEWHERE.
&&
.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
AN APPROACHING LOW PRESSURE SYSTEM WILL BRING STRONG SWRLY FLOW
ALOFT...RESULTING IN CONTINUE LLWS ACROSS MOST OF CENTRAL PA THRU
THIS EVENING.
A FEW ADDITIONAL PERIODS OF RAIN SHOWERS ACCOMPANIED BY WIDESPREAD
MVFR CIGS AND MAINLY VFR VSBYS WILL OCCUR FOR THE REST OF TODAY.
AS LOW PRES CENTER TRACKS WEST OF THE STATE. LIFTING CIGS/IMPROVING
VSBYS WILL BE LIKELY ACROSS SOUTHERN PA LATE THIS AFTN/EVENING...
AS A WARM FRONT LIFTS NORTH OF THE MIDDLE SUSQ VALLEY.
A STRONG COLD FRONT WILL PUSH THROUGH THE REGION THIS EVENING
ACCOMPANIED BY A NARROW BAND OF HEAVY SHRA /AND POSSIBLY EVEN A
RUMBLE OF THUNDER/ FOLLOWED BY WESTERLY WINDS GUSTING BETWEEN 30 AND
35KTS ACROSS MOST OF THE REGION TONIGHT AND EARLY WEDNESDAY. GUSTS
COULD BE BETWEEN 45-50 MPH ACROSS THE NW MTNS AND LAUREL HIGHLANDS.
OUTLOOK...
WED...WESTERLY WINDS - GUSTING TO 35-40KT EARLY ACROSS THE WRN MTNS.
LAKE EFFECT SNOW SHOWERS NEAR..AND TO THE WEST OF KBFD WITH OCNL IFR
CIGS AND VSBYS MAINLY IN THE MORNING. NO SIG WX EXPECTED ELSEWHERE.
THU...SHSN OR EVEN A PERIOD OF STEADY LIGHT SNOW/REDUCED VSBYS
POSS...MAINLY W MTNS.
FRI...NO SIG WX EXPECTED.
SAT...PERIODS OF LGT SNOW NW AND MIXED PRECIP SE.
SUN...NO SIGNIF WX.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WIND ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST WEDNESDAY FOR
PAZ004>006-010-011.
LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 4 PM EST WEDNESDAY FOR
PAZ004.
WIND ADVISORY UNTIL 6 AM EST WEDNESDAY FOR PAZ017-024-033.
&&
$$
SYNOPSIS...LAMBERT
NEAR TERM...LAMBERT
SHORT TERM...CERU/STEINBUGL
LONG TERM...CERU
AVIATION...LAMBERT
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1231 AM EST TUE JAN 17 2012
.SYNOPSIS...
LOW PRESSURE DEVELOPING OVER THE MIDWEST WILL STRENGTHEN AS IT
LIFTS NORTHEAST ACROSS THE LOWER GREAT LAKES AND UP THE ST
LAWRENCE VALLEY. A COLD FRONT TRAILING THE LOW WILL SWEEP ACROSS
THE COMMONWEALTH TONIGHT...FOLLOWED BY A SURGE OF COLDER AIR
BEHIND GUSTY WEST-NORTHWEST WINDS. HIGH PRESSURE WILL MOVE INTO
THE REGION LATER WEDNESDAY INTO EARLY THURSDAY.
&&
.NEAR TERM /UNTIL 7 AM THIS MORNING/...
THE MAJORITY OF MESO OBS ARE ABV FZG AND THEREFORE HAVE ALLOWED
THE SRN SEGMENT OF THE WINTER WX ADVY TO EXPIRE. HOWEVER FURTHER
NORTH AND EAST...THE LATEST MESO OBS AND RUC 925MB TEMPS ARE STILL
BLW FZG IN THE N-CNTRL/ENDLESS MTNS AND PTNS OF THE MID SUSQ VLY SO
WILL KEEP ADVY IN PLACE FOR THESE LOCATIONS. THE SHALLOW LLVL COLD
AIR WILL SLOWLY RETREAT THROUGH THE EARLY MORNING AS MILDER AIR
STREAMS INTO THE REGION FROM THE SW IN ADVANCE OF DEVELOPING LOW
AND TRAILING COLD FRONT OVR THE MIDWEST.
&&
.SHORT TERM /7 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
TUESDAY WILL FEATURE A LOW OVC WITH PERIODS OF MORNING
RAIN...TAPERING TO SHOWERS IN THE AFTERNOON. FOG WILL BE SHROUDING
THE RIDGES AT ELEVATIONS AOA 1700 FT MSL. MAX TEMPS TUESDAY WILL
RANGE FROM THE LOWER 40S ACROSS THE NORTH...TO THE LOWER 50S IN
THE SOUTH /A HEFTY 10-15F ABOVE NORMAL FOR MID JANUARY/. STORM
TOTAL LIQ EQUIV PRECIP BY TUESDAY EVENING WILL AVERAGE BETWEEN
0.50 AND 0.75 OF AN INCH.
THE QUESTION FOR THIS PERIOD IS WHEN AND WHERE THE TRANSITION FROM
RAIN TO SNOW AND ANY CHANGING PRECIPITATION TYPE IN BETWEEN WILL
OCCUR. THE COLD FRONT FROM THIS STORM WILL ENTER WESTERN
PENNSYLVANIA AROUND 00Z. IT THEN MOVES QUICKLY THROUGH ON FAST WESTERLY
FLOW ALOFT. 8H TEMPS DROP ABOUT 18C AND SFC PRESSURE RISES ABOUT
15MB OVERNIGHT. THE MODEL CONSISTENCY SHOWS THAT THERE SHOULD BE
STRONG WINDS AT AND BEHIND THE FRONT AND CONTINUE TO 18Z
WEDNESDAY. DURING THE 00Z TO 03Z HOURS AS DEWPOINT DEPRESSIONS
REMAIN AROUND 0 AND DEWPOINTS ARE ABOVE FREEZING RAIN WILL
DOMINATE. AS THE COLD AIR MOVES QUICKLY THROUGH THE RAIN WILL
QUICKLY TURN TO SNOW...ALLOWING FOR ONLY A BRIEF PERIOD FOR ANY
MIXED PRECIPITATION. IF AND WHEN THERE IS IT WILL BE A RAIN SNOW
MIX...ESPECIALLY THE HIGHER ELEVATIONS WHICH WILL THEN SWITCH TO
SNOW BY 03Z. THE SPEED OF THE SYSTEM...ALONG WITH INCREASE SHEAR WILL
LIMIT SNOW ACCUMULATIONS. ANY SNOW ACCUMULATIONS WILL OCCUR AT THE
END OF THIS SYSTEM AS THE TROUGH LIFTS OUT AND THE WINDS SHIFT TO
THE NORTHWEST...ALLOWING FOR ONLY LAKE EFFECT AND TOPOGRAPHIC SNOW
SHOWERS....FROM 06Z TO AROUND 18Z. IF THE SNOW SETS UP QUICKLY
WITH LITTLE RAIN MIX...AND WITH -15C AT 850 MB THERE COULD BE A SLIGHT
CHANCE FOR AN ADVISORY IN THE NW MTNS. HOWEVER...SINCE DENDRITIC
GROWTH WILL BE LIMITED AND MOST SNOW GENERATION WILL PROBABLY BE
GRANULES AND COLUMNS ALONG WITH THE HIGH SHEAR AND SHORT DURATION OF
THE BEST FETCH WILL WAIT TO ISSUE ANY HIGHLIGHTS.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
COLD AIR WITH PERIODS OF LAKE EFFECT SNOW WILL CONTINUE THROUGH
FRIDAY. TEMPERATURES WILL BE COLD THROUGH FRIDAY...ESPECIALLY AS A
FINGER OF THE JET PROTRUDES THROUGH THE EASTERN GREAT LAKES ON
FRIDAY. WITH WARM AIR ADVECTION NEXT WEEKEND SHOULD SEE WARMER
TEMPERATURES SATURDAY AND SUNDAY. THOUGH THE CURRENT LONG RANGE
MODELS HAVE A WEAK TROUGH PROPAGATING THROUGH...WITH THE EC SHOWING
SLIGHTLY MORE AMPLITUDE...A GREATER NEGATIVE TILT AND SLOWER
PROGRESSION. GFS MOVES THE SYSTEM THROUGH EARLY SATURDAY. THE EC
BRINGING THE SYSTEM THROUGH LATE SATURDAY...EARLY SUNDAY. HOWEVER
THE DICHOTOMY OF THE MODELS REMAINS THAT BY MID SUNDAY THEY ARE ALMOST
180 DEGREES OUT OF EACH OTHER. BASED ON THE CONSENSUS AND RECENT
TRENDS...HAVE BEST PRECIP CHANCES BY MIDDAY SATURDAY...WITH A
POSSIBILITY OF A RAIN SNOW MIX. HAVE BROUGHT UP PRECIP CHANCES ON SUNDAY
SLIGHTLY BUT MAINLY IN THE HIGHER ELEVATIONS. MAINLY DRY
CONDITIONS ELSEWHERE.
&&
.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
AN APPROACHING LOW PRESSURE SYSTEM WILL BRING INCREASING SSW TO
SWRLY FLOW ALOFT...RESULTING IN LLWS ACROSS MOST OF CENTRAL PA
THRU TUESDAY EVENING.
THIS SYSTEM HAS SPREAD A LIGHT WINTRY MIX ACROSS CENTRAL AND
NORTHERN PA THIS EVENING WITH MAINLY RAIN ACROSS THE SOUTH. ANY
MIXED PRECIP ACROSS THE NORTH WILL TRANSITION TO MAINLY JUST OCNL
LIGHT RAIN AFTER MIDNIGHT. HOWEVER...LATEST MDL DATA SUGGESTS
TEMPS COULD LINGER NR THE FREEZING MARK AT IPT UNTIL ARND 09Z.
ENSEMBLE AND 18Z OPER MDL DATA CONTINUE TO INDICATE THE GREATEST
THREAT OF IFR CONDS TONIGHT WILL BE AT BFD...WHERE MOIST SSW FLOW
ASCENDS THE MTNS. OTHERWISE...MDL DATA SUPPORTS NO WORSE THAN
MVFR CIGS/VSBYS OVERNIGHT.
A PERIOD OF STEADY RAIN ACCOMPANIED BY WIDESPREAD IFR VSBYS/CIGS
IS POSSIBLE BTWN 12Z-18Z...AS LOW PRES CENTER TRACKS WEST OF THE
STATE. LIFTING CIGS/IMPROVING VSBYS LIKELY ACROSS SOUTHERN PA BY
AFTN...AS WARM FRONT LIFTS NORTH INTO THE STATE.
A STRONG COLD FRONT WILL PUSH THROUGH THE REGION TUESDAY EVENING FOLLOWED
BY WESTERLY WINDS GUSTING BETWEEN 30 AND 35KTS TUES NIGHT.
OUTLOOK...
WED...NO SIG WX EXPECTED.
THU...SHSN/REDUCED VSBYS POSS...MAINLY W MTNS.
FRI...NO SIG WX EXPECTED.
SAT...LGT FROZEN PRECIP POSS.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR PAZ006-
012-037-041-042-045-046-049>053-058.
&&
$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...DANGELO/CERU
LONG TERM...CERU/STEINBUGL
AVIATION...FITZGERALD
AREA FORECAST DISCUSSION
NWS CORPUS CHRISTI TX
337 PM CST TUE JAN 17 2012
.SHORT TERM (TONIGHT THROUGH WEDNESDAY NIGHT)...A COLD FRONT IS
CURRENTLY DRAPED FROM NORTH OF VICTORIA TO NEAR LAREDO. THE FRONT
WILL PUSH THROUGH THE REST OF THE AREA LATE THIS
AFTERNOON...PUSHING OFFSHORE BY EVENING. WITH A CAP REMAINING OVER
THE AREA DONT EXPECT TO SEE SHOWERS OVER LAND...BUT MAY BE ABLE TO
DEVELOP A FEW OFFSHORE THIS EVENING. RUC GUIDANCE HAS SEEMED
PRETTY REASONABLE WITH FRONTAL TIMING AND WINDS SO LARGELY GOING
WITH THAT FOR WINDS THIS EVENING...EXPECTING A BRIEF INCREASE OVER
LAND AREAS AND THEN AN INCREASE TO 20 TO 25 KNOTS OVER THE WATER.
A SMALL CRAFT ADVISORY IS IN EFFECT FROM 8PM THIS EVENING THROUGH
9AM TOMORROW. BEHIND THE FRONT HIGH PRESSURE WILL QUICKLY BUILD IN
AND LEAD TO LIGHT WINDS TOMORROW ACROSS THE AREA. BY WEDNESDAY
NIGHT WINDS ARE ALREADY SHIFTING TO THE SOUTHEAST. AN AREA OF MID
AND HIGH LEVEL CLOUDS PUSHING IN FROM THE WEST SHOULD KEEP TEMPS
MAINLY IN THE 40S THIS EVENING...WITH SOME UPPER 30S IN THE FAR
NORTHEAST. AFTER NEAR RECORD HIGHS TODAY...MAX TEMPS WILL BE IN
THE 60S AREA WIDE TOMORROW. SOUTHERLY WINDS KEEP TEMPS UP
WEDNESDAY NIGHT.
&&
.LONG TERM (THURSDAY THROUGH TUESDAY)...THURSDAY THROUGH SATURDAY
WILL FEATURE A MAINLY ZONAL FLOW ALOFT WITH A WARMING TREND ACROSS
SOUTH TEXAS...AND ABOVE NORMAL HIGHS. A GRADUAL MOISTENING OF THE
LOWER LEVELS WILL ALSO TAKE PLACE...WITH PERIODS OF OVERNIGHT AND
MORNING FOG/SEA FOG TO CONTEND WITH FRI/SAT. A WEAK FRONTAL BOUNDARY
WILL STALL OVER THE NORTHERN CWA SATURDAY MORNING AND WASH OUT. NEXT
CHANCE OF PRECIP WILL COME LATE SUNDAY INTO MONDAY MORNING AS A
SOUTHERN STREAM SHORTWAVE APPROACHES FROM BAJA CALIFORNIA. WILL KEEP
POPS IN THE 20% RANGE FOR NOW AS THERE HAVE BEEN SOME MODEL
CONSISTENCY ISSUES WITH TIMING/STRENGTH OF DISTURBANCE. THE
DISTURBANCE BECOMES ABSORBED INTO LARGER TROUGH TO THE NORTHWEST ON
MONDAY...WHICH EVENTUALLY PUSHES A COLD FRONT INTO THE AREA TUESDAY.
AGAIN...TIMING AND STRENGTH DIFFERENCES WITH RESPECT TO UPPER LEVEL
TROUGH AND CORRESPONDING COLD FRONT BETWEEN ECMWF/GFS.
&&
.PRELIMINARY POINT TEMPS/POPS...
CORPUS CHRISTI 45 63 48 79 58 / 10 0 0 0 0
VICTORIA 38 61 46 75 57 / 10 0 0 0 0
LAREDO 47 64 52 78 58 / 0 0 0 0 0
ALICE 45 64 48 80 58 / 10 0 0 0 0
ROCKPORT 43 60 49 69 58 / 10 0 0 0 0
COTULLA 41 63 43 78 54 / 0 0 0 0 0
KINGSVILLE 46 64 48 80 58 / 10 0 0 0 0
NAVY CORPUS 47 61 51 73 60 / 10 0 0 0 0
&&
.CRP WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 9 AM CST
WEDNESDAY FOR THE FOLLOWING ZONES: BAYS AND WATERWAYS FROM
BAFFIN BAY TO PORT ARANSAS...BAYS AND WATERWAYS FROM PORT
ARANSAS TO PORT O`CONNOR...COASTAL WATERS FROM BAFFIN BAY
TO PORT ARANSAS OUT 20 NM...COASTAL WATERS FROM PORT
ARANSAS TO MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM
BAFFIN BAY TO PORT ARANSAS FROM 20 TO 60 NM...WATERS FROM
PORT ARANSAS TO MATAGORDA SHIP CHANNEL FROM 20 TO 60 NM.
&&
$$
PZ/83...SHORT TERM
JR/76...LONG TERM
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
902 PM CST WED JAN 18 2012
.UPDATE...
WILL FOLLOW TRENDS IN THE HRRR 4 KM RUN THAT TAKES THE BAND OF
SNOW SHOWERS WITH THE COLD FRONT THROUGH MOST OF THE FORECAST
AREA. LATEST 00Z HRR NOW REACHES MADISON AT MIDNIGHT AND MILWAUKEE
BY 3 AM. THIS MAY BE AN HOUR FAST...BUT WE COULD GET A CONVECTIVE
BURST WITH AROUND 1/2 INCH OF ACCUMULATION. WINDS WILL ALSO PICK
UP WITH THE COLD AIR ADVECTION AND INCREASING LOW LEVEL LAPSE RATES.
00Z NAM SHIFTS THE MAX PRECIP AREA JUST A BIT FARTHER
SOUTH...TAKING THE 0.75 LIQUID EQUIVALENT ACROSS LAFAYETTE COUNTY
WITH 0.38 INCHES FOR MILWAUKEE AND MADISON. LOOK LIKE AN ADVISORY
EVENT FOR MUCH OF THE FORECAST AREA. IF THE GFS THAT HAS HAD A
LITTLE LESS QPF THAN THE NAM TRENDS TOWARD THE NAM...A WATCH MAY
BE NEEDED...ESPECIALLY OVER THE FAR SOUTH.
&&
.AVIATION/06Z TAFS/...
WILL FOLLOW TRENDS IN THE HRRR 4 KM RUN THAT TAKES THE BAND OF
SNOW SHOWERS WITH THE COLD FRONT THROUGH MOST OF THE FORECAST
AREA. LATEST 00Z HRR NOW REACHES MADISON AT MIDNIGHT AND MILWAUKEE
BY 3 AM. THIS MAY BE AN HOUR FAST...BUT WE COULD GET A CONVECTIVE
BURST WITH AROUND 1/2 INCH OF ACCUMULATION. WINDS WILL ALSO PICK
UP WITH THE COLD AIR ADVECTION AND INCREASING LOW LEVEL LAPSE RATES.
THIS FRONT LIKELY TO PRODUCE A BRIEF PERIOD OF IFR VSBYS.
&&
.PREV DISCUSSION... /ISSUED 316 PM CST WED JAN 18 2012/
TONIGHT AND THURSDAY...FORECAST CONFIDENCE MEDIUM TO HIGH.
LOW PRESSURE WILL SHIFT EAST NORTHEAST ACROSS LAKE SUPERIOR TONIGHT.
ASSOCIATED SHORTWAVE TROUGH WILL SWING EAST ACROSS NORTHERN AND
CENTRAL WISCONSIN THIS EVENING...THEN SHIFT EASTWARD LATER TONIGHT.
MAIN AREA OF UPWARD VERTICAL MOTION WITH THIS SYSTEM SHOULD REMAIN
JUST NORTH OF THE AREA...THOUGH NORTHERN SECTIONS OF THE AREA DO SEE
MODEST AMOUNTS OF THIS DURING THE EVENING....WITH SOME LOW TO MID
LEVEL MOISTURE SEEN WITH CLOUD DECK IN MINNESOTA.
WENT WITH CHANCE POPS IN THE FAR NORTH FOR LIGHT SNOW SHOWERS THIS
EVENING...LOWER POPS TO THE SOUTH. CHANCES LOWER AFTER MIDNIGHT AS
SYSTEM SHIFTS EAST. A TENTH OF AN INCH OR SO OF SNOW IS POSSIBLE IN
THE NORTHERN COUNTIES WITH THIS SYSTEM.
MAIN ISSUE WITH THIS SYSTEM IS VERY COLD AIR AND WIND CHILLS LATER
TONIGHT INTO THURSDAY. TIGHT PRESSURE GRADIENT IS EXPECTED WITH THE
PASSAGE OF THE LOW...AHEAD OF AND BEHIND ARCTIC COLD FRONT MOVING
THROUGH THE AREA LATER TONIGHT. GUSTY NORTHWEST WINDS BEHIND THE
FRONT WILL BRING ANOTHER SHOT OF COLD AIR INTO THE AREA...WITH 925MB
TEMPERATURES FALLING INTO THE 15 BELOW TO 20 BELOW ZERO CELSIUS
RANGE.
TEMPERATURES FALLING TO NEAR OR JUST BELOW ZERO IN THE FAR WEST AND
NORTHWEST COUNTIES...WITH THE BRISK NORTHWEST WINDS...SHOULD BRING
WIND CHILL READINGS CLOSE ENOUGH TO 20 BELOW ZERO TO GO WITH A WIND
CHILL ADVISORY FOR LATE TONIGHT THROUGH THURSDAY MORNING. WIND
CHILLS WILL STILL BE BELOW ZERO ELSEWHERE ACROSS THE AREA LATER
TONIGHT INTO THURSDAY MORNING AS WELL. SLIGHTLY MILDER TEMPERATURES
SHOULD BE FOUND IN THE FAR SOUTHEAST.
TEMPERATURES WILL BE VERY SLOW TO RISE THURSDAY AFTERNOON DESPITE
SUNSHINE. SNOW COVER AND WEAKENING COLD AIR ADVECTION SHOULD KEEP
HIGHS IN THE SINGLE DIGITS ABOVE ZERO IN MOST AREAS...TO AROUND 10
ABOVE FAR SOUTHEAST.
THURSDAY NIGHT...FORECAST CONFIDENCE IS HIGH.
HIGH PRESSURE SLIDES OVERHEAD SETTING THE STAGE FOR A RAPID
EVENING DROP IN TEMPS. WE START THE EVENING WITH TEMPS ALREADY
QUITE COLD...IN THE SINGLE DIGITS ABOVE ZERO. A GOOD PART OF THE
EVENING SHOULD HAVE MOSTLY CLEAR SKIES WITH LITTLE OR NO WIND.
HIGH LEVEL CLOUDINESS SPILLS IN TOWARD MIDNIGHT. SO...TEMPS SHOULD
TANK QUICKLY AFTER SUNSET...THEN LEVEL OFF BY MIDNIGHT WITH A SLOW
RISE TOWARD MORNING.
FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM TO HIGH.
A PRETTY CLASSIC FRONTOGENETIC/ISENTROPIC PRECIP EVENT ARRIVES
EARLY THIS PERIOD. AS DISCUSSED IN THE PERIOD ABOVE...TEMPS WILL
BE VERY COLD TO START THE DAY WITH A RETURN SOUTHERLY FLOW ACROSS
IOWA AT 850MB BRINGING A RAPIDLY TIGHTENING BAROCLINIC ZONE TO THE
SOUTHERN GREAT LAKES. THE ARCTIC AIRMASS IS SHALLOW AND HAS QUITE
A LARGE NORTH/SOUTH SLOPE. EVIDENCE OF THIS IS AT 06Z SATURDAY THERE
IS A SFC LOW IS OVER THE LOWER TO MIDDLE MISSISSIPPI VALLEY WHILE
THE ASSOCIATED 850MB SYSTEM IS OVER NRN IL/SRN WI...IMPRESSIVE. A
NICE RIGHT REAR QUAD OF THE UPPER JET WILL GENERATE A NICE AGEO
CIRCULATION ACROSS THIS TIGHT BAROCLINIC ZONE FOR A RATHER DEEP
OMEGA FIELD. THE NAM HAS BEEN THE MOST AGGRESSIVE WITH THE LEADING
WARM NOSE AND THIS IS AN OUTLIER WITH THE REST OF THE MODELS. IT
LIKELY EXPLAINS THE HIGHER QPF NUMBERS AS WELL. CONSENSUS QPF
NUMBERS STILL HAVE BETWEEN .30 TO .40 LIQUID EQUIVALENT. GIVEN THE
COLD AIR...WE SHOULD SEE RATIOS OF 15-20 TO 1. THE GFS HAS A
MASSIVE DGZ LAYER...ABOUT 15KFT AT KMSN. WHILE THE NAM SHOWS AN
INTERVENING WARMER LAYER THAT LIMITS THE DGZ. CIPS ANALOGS
SUGGEST A SOUTHERN CORRECTION MAY BE IN ORDER GOING FORWARD. IF
THE COLD AIR BECOMES DEEPER...AND THAT BAROCLINIC ZONES STAYS MORE
SOUTH...THE CORE OF THE PRECIP WILL FOLLOW A SOUTHERN CORRECTION.
FOR NOW...GIVEN THE QPF AND RATIOS...LOOKING AT A SOLID 5 TO 6
INCHES ACROSS THE SOUTHERN PORTION OF THE FORECAST AREA. THIS IS A
GOOD ADVISORY SITUATION THAT MAY END UP BEING UPGRADED TO A
WARNING IF QPF BEGINS TO INCREASE. CONTEMPLATED A WINTER STORM
WATCH...BUT THERE IS TOO MUCH UNCERTAINTY AT THIS POINT. JUST
CAN/T SEE HIGHER QPF WITH THIS COLD AIR. FOR NOW...NO HEADLINES.
ADVISORY HEADLINES ARE USUALLY LIMITED TO THE SECOND AND POSSIBLY
THIRD PERIOD.
ALSO...THERE COULD BE SOME LAKE ENHANCEMENT LATER FRIDAY AS THE
WEAK FLOW TURNS ONSHORE. LOOK FOR THE SNOW TO THEN WIND DOWN FROM
WEST TO EAST FRIDAY NIGHT...BUT SOME LAKE EFFECT MAY CONTINUE A
WHILE LONGER.
SATURDAY...FORECAST CONFIDENCE IS MEDIUM.
MAIN CONCERN HERE IS WHETHER WE WILL HAVE A FAVORABLE TRAJECTORY
OFF THE LAKE FOR SOME LAKE EFFECT SNOW SHOWERS IN THE FAR
SOUTHEAST CORNER OF THE CWA. MODELS AREN/T IN GOOD AGREEMENT
HERE...BUT HAVE THROWN A CHANCE OF SHOWERS IN THERE FOR NOW.
SUNDAY AND SUNDAY NIGHT...FORECAST CONFIDENCE IS LOW.
THE GFS AND THE ECMWF ARE NOT IN GOOD AGREEMENT WITH THE NEXT LOW
ARRIVING THIS PERIOD. THE EC NOW SHOWS A POTENT STORM ROLLING UP
ACROSS NORTHEAST ILLINOIS. TEMPS LOOK QUESTIONABLE FOR PRECIP
TYPE...ESPECIALLY ACROSS THE SOUTHEAST CORNER. THE GFS HAS A LOW
MOVING ACROSS LAKE SUPERIOR WITH A TRAILING COLD FRONT. STAY
TUNED.
MONDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE IS LOW.
THINGS SHOULD QUIET DOWN MONDAY AND TUESDAY BEFORE THE NEXT SYSTEM
ARRIVES ON WEDNESDAY. ITS AN ACTIVE PATTERN OVER THE NEXT
WEEK.
AVIATION/00Z TAFS/...
SOUTH WINDS WILL BECOME GUSTY BY EARLY EVENING...WITH GUSTS TO
AROUND 20 KNOTS AT TIMES. AREA OF MID LEVEL CLOUDS WILL SHIFT EAST
THROUGH TAF SITES LATE THIS AFTERNOON AND EARLY THIS EVENING.
THESE WINDS WILL REMAIN GUSTY TONIGHT INTO THURSDAY...AS THEY SHIFT
NORTHWEST BETWEEN 08Z TO 11Z THURSDAY BEHIND ARCTIC COLD FRONT.
GUSTS IN THE LOWER 20 KNOT RANGE ARE EXPECTED. VFR CEILINGS MOVING
BACK IN BY MID EVENING SHOULD LOWER TO MVFR LATER TONIGHT INTO
THURSDAY MORNING...AS ALBERTA CLIPPER LOW MOVES THROUGH THE REGION.
AT THIS TIME...ANY LIGHT SHOW SHOWERS SHOULD REMAIN NORTH OF TAF
SITES TONIGHT...SO LEFT MENTION OUT OF TAFS. COULD SEE FLURRIES AT
TIMES...BUT NO ACCUMULATIONS ARE EXPECTED AT TAF SITES.
HIGH PRESSURE MOVING INTO THE REGION LATER THURSDAY AFTERNOON SHOULD
BRING WIND GUSTS DOWNWARD...ESPECIALLY AT MADISON.
MARINE...
GALE WARNING REMAINS IN EFFECT THROUGH 18Z THURSDAY ACROSS THE
NEARSHORE WATERS. TIGHT PRESSURE GRADIENT AND GOOD LOW LEVEL MIXING
WILL ALLOW FOR FREQUENT UP TO 35 KNOT SOUTH WINDS TO MIX DOWN TO THE
SURFACE TONIGHT.
WINDS WILL VEER NORTHWEST BEHIND ARCTIC COLD FRONT LATER
TONIGHT...WITH COLDER AIRMASS ALLOWING FOR CONTINUED GOOD MIXING OF
UP TO 35 KNOT WINDS INTO THURSDAY MORNING.
HIGH WAVES ARE EXPECTED TO DEVELOP...ESPECIALLY TOWARD THE OPEN
WATERS. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR THURSDAY
AFTERNOON/EVENING...AS WINDS AND WAVES SLOWLY SUBSIDE WITH HIGH
PRESSURE MOVING INTO THE REGION.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WIND CHILL ADVISORY FROM 3 AM TO NOON CST THURSDAY FOR WIZ046-
047-056-057-062-067.
LM...GALE WARNING UNTIL NOON CST THURSDAY FOR LMZ643>646.
&&
$$
UPDATE...HENTZ
TONIGHT/THURSDAY AND AVIATION/MARINE...WOOD
THURSDAY NIGHT THROUGH WEDNESDAY...DAVIS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
351 AM CST TUE JAN 17 2012
.SHORT TERM...TODAY THROUGH THURSDAY
302 AM CST TUE JAN 17 2012
AT 3 AM...A LOW PRESSURE SYSTEM WAS MOVING NORTHEAST THROUGH
SOUTHERN ILLINOIS. ON THE SOUTH SIDE OF THIS SYSTEM...THERE HAS
BEEN SEVERAL TORNADO WARNINGS OVERNIGHT ACROSS THE SPRINGFIELD
MISSOURI COUNTY WARNING AREA. MEANWHILE TWO AREAS OF SNOW ARE
STARTING TO DEVELOP ACROSS THE UPPER MIDWEST. THE FIRST AREA OF
SNOW IS ASSOCIATED WITH STRONG 900 TO 800 MB FRONTOGENESIS ACROSS
SOUTHERN IOWA. A SECOND AREA OF SNOW IS LOCATED ACROSS SOUTHWEST
MINNESOTA AND NORTHWEST IOWA. THIS SNOW IS ASSOCIATED WITH A
POTENTIAL VORTICITY ANOMALY.
BOTH THE 17.00Z AND 17.06Z MODELS ARE IN VERY GOOD AGREEMENT THAT
A SHORT WAVE TROUGH WILL MOVE THROUGH SOUTHEAST MINNESOTA...
NORTHEAST IOWA...AND WEST CENTRAL AND CENTRAL WISCONSIN THROUGH
EARLY THIS AFTERNOON. THERE IS DEEP OMEGA ASSOCIATED WITH THIS
WAVE WHICH WILL ALLOW THE DRY AIR CURRENTLY LOCATED BETWEEN 5 AND
15K FEET TO QUICKLY SATURATED. WITH THIS SYSTEM SOMEWHAT MOISTURE
STARVED INITIALLY... THINKING ONLY AROUND AN INCH ACROSS SOUTHEAST
MINNESOTA AND MUCH OF NORTHEAST IOWA. FURTHER EAST...THE MOISTURE
IS A BIT MORE PLENTIFUL AND THERE WILL BE AT LEAST 7K FEET OF
DENDRITES. THIS SHOULD RESULT IN 1 TO 2 INCHES ALONG AND NORTH OF
THE INTERSTATE 90 CORRIDOR.
MEANWHILE IN CLAYTON COUNTY IN NORTHEAST IOWA...AND CRAWFORD...
GRANT...AND RICHLAND COUNTIES IN SOUTHWEST WISCONSIN...THE STRONG
POTENTIAL VORTICITY ANOMALY WILL MEET UP WITH STRONG 900 TO 800 MB
FRONTOGENESIS. IN ADDITION...THERE WILL BE AT LEAST 6 HOURS OF AT
LEAST 7K FEET OF DENDRITES. THIS IS ALSO THE AREA WHERE THERE IS
THE BEST MOISTURE /TWO TENTHS TO A QUARTER INCH/. THINKING THAT
THERE WILL BE HIGH PROBABILITY OF 2 TO 4 INCHES OF SNOW ACROSS
THIS AREA. THIS IS IN GOOD AGREEMENT WITH THE 16.21Z SREF DATA. IN
ADDITION...THERE WILL BE NORTHWEST WINDS OF 15 TO 25 MPH. THIS
WILL RESULT IN SOME BLOWING AND DRIFTING SNOW. DUE TO THE
COMBINATION OF SNOW AND WINDS...A WINTER WEATHER ADVISORY HAS BEEN
ISSUED FROM 5 AM THIS MORNING THROUGH 3 PM THIS AFTERNOON.
ON WEDNESDAY AFTERNOON AND EVENING...THE MODELS CONTINUE TO SHOW
THAT ANOTHER STRONG SHORT WAVE TROUGH WILL MOVE SOUTHEAST THROUGH
THE AREA. MUCH OF THE LIFT ASSOCIATED WITH THIS WAVE GOES TOWARD
SATURATING THE VERY DRY AIR AHEAD OF IT. LIKE THE PAST COUPLE OF
DAYS...IT LOOKS LIKE THE BEST PROBABILITIES /ALBEIT SMALL/ FOR
SNOW WILL BE ALONG AND NORTH OF INTERSTATE 94. FURTHER SOUTH...
THERE MAY SOME SNOW FLURRIES DURING THIS TIME PERIOD. WITH THERE
BEING WARM AIR ADVECTION AHEAD OF THIS WAVE...WENT WITH A NON
DIURNAL TEMPERATURE CURVE TO KEEP THE TEMPERATURES WARMER DURING
THE EVENING AND ALSO HANDLE THE POTENTIAL THAT THE HIGH
TEMPERATURE MAY OCCUR DURING THE LATE AFTERNOON OR EARLY EVENING.
ON THURSDAY...STRONG COLD AIR ADVECTION MOVES SOUTHWARD INTO THE
AREA. HOWEVER...IT DOES NOT LOOK QUITE AS COLD AS IT WAS
ADVERTISED TO BE OVER THE WEEKEND. EVEN THOUGH THE TEMPERATURES
MAY BE A BIT WARMER...THE WIND CHILLS DURING THE DAY WILL RANGE
FROM 15 TO 25 BELOW.
.LONG TERM...THURSDAY NIGHT THROUGH MONDAY
302 AM CST TUE JAN 17 2012
ON THURSDAY NIGHT AND FRIDAY...THE MODELS CONTINUE TO SHOW THAT
ANOTHER STRONG SHORT WAVE WILL MOVE THROUGH THE REGION. THE LAST
FOUR RUNS OF THE GFS HAVE CONSISTENTLY SHOWED THAT THIS SYSTEM WILL
MOVE ALONG THE STRONG BAROCLINIC ZONE AND AFFECT THE FORECAST
AREA FROM LATE THURSDAY NIGHT INTO FRIDAY. IN ADDITION...THE QPF
CONTINUES TO INCREASE IN THIS MODEL. AT THIS TIME...IT LOOKS LIKE
THIS SYSTEM MAY PRODUCE 3 TO 6 INCHES OF SNOW IN THE GFS.
MEANWHILE THE ECMWF CONTINUES TO STRUGGLE ON THE TRACK OF THIS
SYSTEM. SINCE THIS MODEL TENDS TO DO BETTER DURING THIS TIME
FRAME...IT DOES INTRODUCE SOME UNCERTAINTY ON WHERE TO RAISE THE
PRECIPITATION CHANCES AND HOW MUCH SNOW MAY FALL ACROSS THE AREA.
DUE TO THIS...ONLY RAISED THE PRECIPITATION CHANCES BY 10 TO 20
PERCENT.
BEHIND THIS SYSTEM...MANY OF THE MODELS CONTINUE TO SHOW THAT THE
POLAR JET WILL RETREAT BACK TO THE NORTH AS THE ARCTIC OSCILLATION
STARTS TO BECOME MORE POSITIVE. THE GFS IS THE SLOWEST AT THIS
OCCURRING. MEANWHILE THE ECMWF AND GEM ARE THE MOST AGGRESSIVE
WITH THIS PATTERN CHANGE. FOR THE TIME BEING...JUST WENT
CONSERVATIVE AND MADE NO CHANGES TO THE ALL BLEND FOR THE WEEKEND
AND EARLY NEXT WEEK.
&&
.AVIATION...THROUGH 06Z WEDNESDAY
1117 PM CST MON JAN 16 2012
THE 17.00Z MODELS HAVE COME INTO BETTER CONSENSUS THAT THE MAIN
SHORT WAVE TROUGH COMING OUT OF THE ROCKIES WILL TAKE A SLIGHTLY
MORE SOUTHERN TRACK. THIS IS NOT EXPECTED TO GO ACROSS NORTHERN
IOWA AND THE WISCONSIN/ILLINOIS BORDER. THIS WILL FOCUS THE BEST
FORCING JUST TO THE SOUTH OF THE TAF SITES BUT THERE STILL APPEARS
TO BE ENOUGH FORCING TO PRODUCE LIGHT SNOW AT BOTH TAF SITES. A
WEAKER SHORT TROUGH FARTHER NORTH IN THE LONG WAVE TROUGH WILL
PRODUCE SOME WEAK LIFT ACROSS THE AREA AS IT COMES THROUGH LATE
TONIGHT AND TUESDAY MORNING BRINGING ABOUT 12 PVU/S OF VORTICITY
ADVECTION IN THE 500-300 MB LAYER. THERE STILL LOOKS TO BE SOME
WEAK FRONTOGENESIS IN THE 850-700 MB LAYER ASSOCIATED WITH THIS
WAVE. THE QG CONVERGENCE WILL BE WEAK BELOW 500 MB BUT BECOMES
QUITE STRONG AROUND 12Z ABOVE 500 MB AS THE TWO WAVE COME ACROSS
THE AREA. ALSO STILL LOOKING AT A BROAD AREA OF ABOUT 2 UBAR/S OF
UPGLIDE ON THE 280K ISENTROPIC SURFACE UNTIL THE LONG WAVE TROUGH
PASSES THROUGH DURING THE AFTERNOON. THE NAM AND 17.03Z RUC BUFKIT
SOUNDINGS SUGGEST THERE WILL BE A DRY MID LEVEL LAYER TO OVERCOME
AND THE 00Z RAOBS FROM KDVN AND KGRB DO CONFIRM THAT THIS IS REAL.
HAVE THUS PUSHED BACK THE STARTING TIME OF THE SNOW A LITTLE AND
THEN BRING THE VISIBILITY DOWN TO IFR AROUND 12Z WHEN ALL THE
FORCING COMES TOGETHER TO PRODUCE ABOUT A 5 TO 6 HOURS OF SOME
DECENT SNOW. ONCE THE FORCING STARTS TO MOVE EAST...THE SNOW
SHOULD QUICKLY END WITH THE VISIBILITY AND CEILINGS RETURNING TO
VFR BY MID TO LATE AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
250 PM CST MON JAN 16 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM...BOYNE
LONG TERM...BOYNE
AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1131 PM CST MON JAN 16 2012
.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT
250 PM CST MON JAN 16 2012
FORECAST FOCUS REMAINS THE PCPN CHANCES FOR THE NEXT FEW DAYS...WITH
A QUICK COOL DOWN AT MID WEEK.
16.12Z MODEL RUNS AND THE FORECAST STILL LOOKS ON TRACK WITH THE
PCPN POTENTIAL FOR LATE TONIGHT/TUE. LATEST WATERVAPOR IMAGERY
DEPICTED AN UPPER LEVEL SHORTWAVE TROUGH DRIVING ACROSS THE SOUTHERN
PLAINS...MOVING NORTHEAST...WHILE ANOTHER TROUGH WAS MOVING ACROSS
THE CENTRAL/SOUTHERN ROCKIES. GFS/NAM TAKE THIS INTO SOUTHERN
MICH...WITH THIS FEATURE WORKING ON THE SFC FRONT THAT PASSED ACROSS
THE LOCAL AREA TODAY. INTERACTING WITH LOW LEVEL MOISTURE
TRANSPORT...EXPECT AREAS OF PCPN TO DEVELOP AROUND THE FRONT AND
SHORTWAVE TRACK. MOST SHOULD STAY SOUTH OF THE FORECAST AREA
INITIALLY...BUT MODELS HAVE BEEN BRINGING THE NORTHERN EDGE OF THE
PCPN INTO PORTIONS OF NORTHEAST IA/SOUTHWEST WI TONIGHT. WITH GOOD
ISENTROPIC UPGLIDE IN THIS REGION AND INCREASING LOW LEVEL
SATURATION...THIS LOOKS REASONABLE. HOWEVER...NORTH-SOUTH RUNNING
X-SECTIONS AND BUFKIT SOUNDINGS IN THIS REGION KEEP THE SATURATION
RELATIVELY SHALLOW INITIALLY...AND MORE SUPPORTIVE OF RAIN/FREEZING
RAIN //OR DRIZZLE// RATHER THAN SNOW. ICE GRADUALLY GETS INTRODUCED
INTO CLOUD TOPS OVERNIGHT AS SATURATION DEEPENS WITH THE APPROACH OF
ANOTHER SHORTWAVE TROUGH. WILL KEEP THIS FREEZING PCPN CONFINED TO
THE SOUTH FOR NOW. VERTICAL MOISTURE PROFILES DEEPENS QUICKER NORTH
OF THERE TONIGHT...FAVORING SNOW. THERE COULD BE A COUPLE HOURS
WHERE FREEZING PCPN COULD OCCUR...BUT CONFIDENCE NOT HIGH ENOUGH TO
ADD INTO THE FORECAST AT THIS TIME. STILL...TRENDS WILL HAVE TO BE
MONITORED AND CHANGES MADE IF THIS DOES COME TO FRUITION.
THE NORTH-SOUTH RUNNING GFS/NAM X-SECTIONS SATURATE THE ATMOSPHERE
BETWEEN 09-12Z TUE...AS THAT NEXT SHORTWAVE FROM THE ROCKIES MOVES
INTO MN. DECENT QG CONVERGENCE WITH THIS FEATURE...ESPECIALLY FOR
MN/NORTHERN WI. SHOULD SEE AREAS OF LIGHT SNOW IN RESPONSE TO THE
FORCING AND SATURATION FOR TUES MORNING INTO THE AFTERNOON...EXITING
EAST BY LATE AFTERNOON/EVENING. BUFKIT SOUNDINGS CONTINUE TO SHOW A
DEEP DENDRITIC LAYER FOR A FEW HOURS...BUT THE FORCING ISN/T OVERLY
STRONG NOR IS THE MOISTURE THAT ABUNDANT. PLUS...THIS SYSTEM IS A
QUICK MOVER. SO...SNOW TOTALS SHOULD BE ON THE LOW-SIDE...WITH 1 TO
2 INCHES STILL LOOKING REASONABLE. COBB OUTPUT ALSO SUPPORTS THIS.
ALONG WITH THE PRECIPITATION WILL COME A SHOT OF COLDER AIR. 850 MB
TEMPS ARE PROGGED TO DROP FROM AROUND -2 C AT 00Z TUE TO -14 C AT
00Z WED. STEADY TO PERHAPS SLOWLY FAILING TEMPS ARE EXPECTED FOR
TUES AS A RESULT. TUE HIGHS WILL LIKELY BE AT MIDNIGHT TONIGHT. HIGH
PRESSURE MOVES OVERHEAD FOR WED NIGHT...AND WITH SOME FRESH SNOW
COVER...LOWS WILL BOTTOM OUT IN THE SINGLE DIGITS ABOVE/BELOW ZERO.
16.12Z MODEL RUNS NEXT SLIDE ANOTHER UPPER LEVEL TROUGH ACROSS THE
REGION ON WED/WED EVENING...WITH RUNS IN PREVIOUS DAYS HAVING KEPT
THIS FEATURE A BIT MORE NORTH. NOT A LOT OF MOISTURE WITH THIS
INITIALLY AFTER THE DRIER/COLDER AIR WITH THE AREA OF HIGH
PRESSURE...BUT SOME INDICATION OF AN INCREASE IN LOW SATURATION OUT
AHEAD OF THE SYSTEM/S ASSOCIATED SFC FRONT. THE DEEPER SATURATION
COMES WITH THE TROUGH ITSELF...AND IS STILL PREDOMINATELY ACROSS
MN/NORTHERN WI. FORCING WITH THE SHORTWAVE SHOULD PRODUCE SOME SNOW
FOR THE REGION...WITH MINOR ACCUMULATIONS UP TO AN INCH CURRENTLY
EXPECTED. IF THE LOW SATURATION DEVELOPS AS AGGRESSIVELY AHEAD OF
THE FRONT AS PROGGED BY THE NAM...A SHORT PERIOD OF FREEZING PCPN
WOULD BE POSSIBLE BEFORE FULL SATURATION CHANGES ANY PCPN OVER SNOW.
THE NAM WAS TOO ENTHUSIASTIC ON THE LOW SATURATION LAST NIGHT...AND
FEEL IT MIGHT BE OVERDOING IT AGAIN. WILL LEAN ON THE GFS/EC IN THIS
STEAD.
.LONG TERM...FRIDAY THROUGH MONDAY
250 PM CST MON JAN 16 2012
A SHORTWAVE TROUGH WILL BE PASSING EAST/SOUTHEAST ACROSS THE AREA
EARLY ON FRIDAY WITH THE ECMWF AND GFS EXITING IT EAST IN THE
AFTERNOON...WITH THE GEM LINGERING IT A BIT LONGER. SOME DIFFERENCES
IN POSITIONING TOO...WITH THE EC FARTHEST NORTH...GFS SOUTH...AND
GEM IN THE MIDDLE. STILL...THE SHORTWAVE REMAINS PROGGED TO MOVE
ACROSS THE FORECAST AREA...WITH THE SOUTHERN 1/2 LOOKING MORE LIKELY
FOR ACCUMULATIONS. COULD SEE A FEW INCHES FROM THIS QUICK MOVING
SYSTEM.
SOME DISAGREEMENTS AS WE HEAD INTO THE WEEKEND WITH THE GFS SLIDING
A SHORTWAVE/SFC FRONT ACROSS THE UPPER MISSISSIPPI RIVER VALLEY ON
SAT WHILE THE GEM/EC POINT TO MORE WEAK RIDGING. GOING TO SIDE
TOWARD THE RIDGING/CONSENSUS SOLUTION FOR NOW. IT DOES LOOK WARMER
FOR THE WEEKEND AS A SOUTHERLY FETCH RETURNS.
&&
.AVIATION...THROUGH 06Z WEDNESDAY
1117 PM CST MON JAN 16 2012
THE 17.00Z MODELS HAVE COME INTO BETTER CONSENSUS THAT THE MAIN
SHORT WAVE TROUGH COMING OUT OF THE ROCKIES WILL TAKE A SLIGHTLY
MORE SOUTHERN TRACK. THIS IS NOT EXPECTED TO GO ACROSS NORTHERN
IOWA AND THE WISCONSIN/ILLINOIS BORDER. THIS WILL FOCUS THE BEST
FORCING JUST TO THE SOUTH OF THE TAF SITES BUT THERE STILL APPEARS
TO BE ENOUGH FORCING TO PRODUCE LIGHT SNOW AT BOTH TAF SITES. A
WEAKER SHORT TROUGH FARTHER NORTH IN THE LONG WAVE TROUGH WILL
PRODUCE SOME WEAK LIFT ACROSS THE AREA AS IT COMES THROUGH LATE
TONIGHT AND TUESDAY MORNING BRINGING ABOUT 12 PVU/S OF VORTICITY
ADVECTION IN THE 500-300 MB LAYER. THERE STILL LOOKS TO BE SOME
WEAK FRONTOGENESIS IN THE 850-700 MB LAYER ASSOCIATED WITH THIS
WAVE. THE QG CONVERGENCE WILL BE WEAK BELOW 500 MB BUT BECOMES
QUITE STRONG AROUND 12Z ABOVE 500 MB AS THE TWO WAVE COME ACROSS
THE AREA. ALSO STILL LOOKING AT A BROAD AREA OF ABOUT 2 UBAR/S OF
UPGLIDE ON THE 280K ISENTROPIC SURFACE UNTIL THE LONG WAVE TROUGH
PASSES THROUGH DURING THE AFTERNOON. THE NAM AND 17.03Z RUC BUFKIT
SOUNDINGS SUGGEST THERE WILL BE A DRY MID LEVEL LAYER TO OVERCOME
AND THE 00Z RAOBS FROM KDVN AND KGRB DO CONFIRM THAT THIS IS REAL.
HAVE THUS PUSHED BACK THE STARTING TIME OF THE SNOW A LITTLE AND
THEN BRING THE VISIBILITY DOWN TO IFR AROUND 12Z WHEN ALL THE
FORCING COMES TOGETHER TO PRODUCE ABOUT A 5 TO 6 HOURS OF SOME
DECENT SNOW. ONCE THE FORCING STARTS TO MOVE EAST...THE SNOW
SHOULD QUICKLY END WITH THE VISIBILITY AND CEILINGS RETURNING TO
VFR BY MID TO LATE AFTERNOON.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
250 PM CST MON JAN 16 2012
WI...NONE.
MN...NONE.
IA...NONE.
&&
$$
SHORT TERM... RIECK
LONG TERM.... RIECK
AVIATION...04
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1003 PM MST WED JAN 18 2012
.AVIATION /FOR 06Z TAF ISSUANCE/...
MODERATE TO SEVERE MECHANICAL TURBULENCE IS EXPECTED ACROSS THE
REGION FOR THE NEXT 24 HOURS...ESPECIALLY NEAR THE DIVIDE. EXPECT
IFR CONDITIONS TO DEVELOP ALONG THE NRN DIVIDE AS SNOW INCREASES
ALONG THE PARK AND GORE RANGES OVERNIGHT AND CONTINUES INTO
THURSDAY.
VFR CONDITIONS WILL PERSIST AT ALL TAF SITES. HOWEVER AREAS OF
LIGHT SNOW WILL BE IN THE VICINITY OF KASE AND KEGE. THERE IS A
SLIGHT CHANCE THAT 5SM -SN BRN025 CONDITIONS WILL OCCUR AT THESE
AIRPORTS.
&&
.PREV DISCUSSION /ISSUED 711 PM MST WED JAN 18 2012/...
UPDATE...
THE DEEPER MOISTURE PLUME REMAINS NORTH OF COLORADO BUT EXPECTED
TO SAG SOUTHWARD LATER THIS EVENING. SNOW HAS NOT STARTED OVER THE
WEST SIDE OF THE DIVIDE JUST YET...BUT MODELS INDICATE SNOW WILL
BE EXPANDING SOUTHWARD OVER THE NRN DIVIDE AND NEAR VAIL PASS
BETWEEN 8 PM AND 11 PM THIS EVENING. A LITTLE CONCERNED THAT WEST
SOUTHWEST FLOW AT MOUNTAIN TOP MAY SHELTER VAIL PASS AND SNOW MAY
BE HARD PRESS TO DEVELOP THERE. THE LATEST HRRR MODEL KEPT THE
SNOW EAST OF VAIL PASS. WILL SEE WHAT EVOLVES DURING THE NEXT 3 TO
6 HOURS.
PREV DISCUSSION /ISSUED 323 PM MST WED JAN 18 2012/...
SHORT TERM /TONIGHT THROUGH FRIDAY/...
THE PACIFIC MOISTURE TAP HAS OPENED UP...EXTENDING FROM THE PACIFIC
NORTHWEST BACK TO HAWAII AND BEYOND ON WATER VAPOR SATELLITE IMAGES.
A SERIES OF SHORTWAVE TROUGHS ACROSS THE NORTHERN PACIFIC OCEAN WILL
TAP THIS MOISTURE AS THEY MOVE INLAND ACROSS THE NORTHERN AND CENTRAL
ROCKIES IN THE DAYS AHEAD.
THE FIRST SHORTWAVE WAS MOVING ACROSS OREGON/WASHINGTON BUT WILL GET
STRETCHED AND WEAKEN BY THE TIME IT ZIPS ACROSS THE NORTH TONIGHT.
REGIONAL RADAR SHOWING PRECIP ACROSS SRN ID/NRN NV/NW UT...AND THIS
DEEPER MOISTURE IS EXPECTED TO STEADILY ADVANCE INTO NE UT/WRN CO
TONIGHT CAUSING SNOW TO INCREASE ACROSS THE NORTHERN AND CENTRAL
MTNS. THIS COUPLED WITH STRONG WINDS WILL PRODUCE HAZARDOUS WINTER
CONDITIONS IN THE ELKHEAD/PARK/GORE/FLATTOP/ELK MTNS TONIGHT INTO
THU MORNING. MAIN FORCING LOOKS TO BE WARM ADVECTION AND PERSISTENT
AND MOIST WESTERLY OROGRAPHIC FLOW SLAMMING INTO THE MTNS. MODELS
INDICATE 700 MB /ROUGHLY 10K FEET ELEVATION/ WESTERLY WINDS IN THE
40-55 KT RANGE NORTH OF I-70. LOOKS LIKE A DOWNTURN IN SNOW ACTIVITY
LATER BY THU AFTERNOON IN BETWEEN SHORTWAVES...WITH THE NEXT AND
STRONGER WAVE AFFECTING THE FORECAST AREA THU NIGHT INTO FRI. IF
CURRENT MODELS ARE CORRECT...SNOW COULD LAST LONGER INTO FRI THAN
CURRENT WINTER HIGHLIGHT SUGGEST. BUT...WITH TIMING OFTEN
PROBLEMATIC IN THESE FAST ZONAL FLOW REGIMES...WILL NOT DO ANY
ADJUSTING AT THIS TIME. THE EASTERN UINTA MTNS ARE EXPECTED TO
GENERALLY BE SHADOWED BY THE HIGHER MTNS TO THEIR WEST WITH ONLY
SOME LIGHT ACCUMULATIONS.
ADDED A BLIZZARD WARNING FOR CO ZONE 10 /GORE AND ELK MTNS/ TO
THE MIX OF WINTER HIGHLIGHTS FOR THE NORTHERN CO MTNS TONIGHT AND
THU MORNING. MOST CONCERNED ABOUT VAIL PASS AND SURROUNDING AREAS
WHERE BLOWING SNOW AND STRONG WINDS SHOULD POSE A SIGNIFICANT
DANGER TO TRAVEL OVER I-70 TONIGHT. LOWER AND MORE WESTERN VALLEY
AREAS OF ZONE 10 NOT LIKELY TO BE AS AFFECTED. THANKS FOR THE
COORDINATION WFO BOU AND PUB.
THERE IS OVERLAP OF PRODUCTS AT THIS TIME BUT EXPECT THE WIND
HIGHLIGHTS TO BE CANCELLED AS THE SNOW/BLIZZARD HIGHLIGHTS GO
INTO EFFECT THIS EVENING.
AN AREA THAT BEARS WATCHING IS THE STEAMBOAT VALLEY. NAM FORECAST
SOUNDINGS HAVE THE LOWER ATMOSPHERE BECOMING NEARLY SATURATED AND
ISOTHERMAL IN THE LOWER END OF THE FAVORABLE SNOW GROWTH REGIME FOR
A TIME TONIGHT...OFTEN FAVORABLE FOR ENHANCED SNOW PRODUCTION.
RAISED POPS TO LIKELY TONIGHT AND ADDED A COUPLE INCHES OF
ACCUMULATION FOR THE VALLEY FROM ABOUT HAYDEN EAST TO STEAMBOAT.
STEAMBOAT VALLEY COULD SEE ACCUMULATING SNOW AGAIN THU NIGHT/FRI
MORNING.
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
ACTIVE PATTERN WILL CONTINUE AS THE MOIST AND ENERGETIC FLOW OVER
THE REGION PERSISTS THROUGH THE LONG TERM PERIOD. A COUPLE OF
SHORTWAVE TROUGHS WILL MOVE ACROSS THE WESTERN CONUS BEGINNING ON
SATURDAY. EACH WAVE WILL BRING A ROUND OF SNOW...ESPECIALLY FOR
THE MOUNTAINS...AS IT SWEEPS OVER EASTERN UTAH AND WESTERN
COLORADO. THE NORTH WILL GENERALLY BE FAVORED. DUE TO THE FAST
PACIFIC FLOW FEEL THAT MODEL TIMING WILL CONTINUE TO EVOLVE
SOMEWHAT...BUT IN GENERAL MODELS SHOW EXCELLENT AGREEMENT.
THE PERIOD BEGINS IN A LULL AS A FLAT SHORTWAVE RIDGE PASSES
FRIDAY NIGHT. THEN PRECIPITATION WILL SPREAD IN ON SATURDAY AS
THIS PERIOD/S FIRST TROUGH APPROACHES AND MOVES OVERHEAD SAT NIGHT.
THE PATTERN BECOMES MORE AMPLIFIED BUT STILL PROGRESSIVE AS THIS
TROUGH DIGS INTO THE CENTRAL CONUS...AND A RIDGE FOLLOWS ACROSS
THE WEST. SNOW WILL GRADUALLY WIND DOWN ON SUN/SUN NIGHT AS THE
RIDGE AXIS PASSES OVERHEAD. THE NEXT WAVE APPROACHES ON MONDAY
WITH THE TROUGH AXIS REACHING WESTERN COLORADO MONDAY EVENING.
AGAIN MODEL CONSISTENCY QUITE HIGH. AFTER THIS WAVE MODELS
INDICATE A LESS PROGRESSIVE FLOW AS HIGH PRESSURE BUILDS OFF THE
SOUTHERN CALIFORNIA COAST...AND LOW PRESSURE OVER THE GREAT LAKES
TO THE SOUTHERN PLAINS. NORTHWEST FLOW WILL DEVELOP OVER OUR AREA
AND PERSIST THROUGH THE END OF THE PERIOD. EXPECT THAT THE
NORTHERN DIVIDE AREA WILL CONTINUE TO SEE SNOW SHOWERS AT TIMES IN
THIS FAVORABLE NORTHWEST FLOW.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...HIGH WIND WARNING UNTIL NOON MST THURSDAY FOR ZONE 012.
WIND ADVISORY UNTIL NOON MST THURSDAY FOR ZONES 018-019.
WINTER STORM WARNING UNTIL 9 AM MST FRIDAY FOR ZONE 004.
BLIZZARD WARNING UNTIL NOON MST THURSDAY FOR ZONE 010.
WINTER WEATHER ADVISORY UNTIL 9 AM MST FRIDAY FOR ZONE 013.
UT...NONE.
&&
$$
SHORT TERM...JAD
LONG TERM....EH
AVIATION.....PF
AREA FORECAST DISCUSSION..CORRECTED
NWS MIAMI FL
324 AM EST THU JAN 19 2012
CORRECTION TO THIRD PARAGRAPH.
.DISCUSSION...
LATEST DEW POINT SURFACE ANALYSIS REVEALS LEADING EDGE OF WEAK
FRONTAL BOUNDARY CURRENTLY ACROSS SOUTH CENTRAL FLORIDA BETWEEN
ORLANDO AND LAKE OKEECHOBEE. ANALYSIS OF MODEL GUIDANCE TRACKING THIS
FEATURE INDICATES THE BOUNDARY WILL BE ACROSS SOUTH FLORIDA BY
LATE MORNING AND/OR EARLY AFTERNOON. GLOBAL MODELS IN FACT BRING
IT THROUGH THE AREA BUT THE HIRES MODELS INCLUDING NCEP HIRES NMM
AND ARW AS WELL AS THE LOCAL WRF AND THE RUC INDICATE THE BOUNDARY
WILL SIMPLY DISSIPATE ACROSS THE AREA AS IT MOVES INTO SOUTH
FLORIDA TODAY. EITHER WAY DRIER AIR WILL BE MOVING INTO THE AREA
WITH IT. AHEAD OF IT, RADAR AND SATELLITE INDICATED SOME
CONVECTION EARLIER THIS MORNING MOVING INTO THE GULF WATERS BUT
IT HAS DISSIPATED SINCE THEN AS LOW LEVEL FORCING WITH THE FRONT
WEAKENS AND AS IT MOVES FARTHER AWAY FROM UPPER LEVEL DYNAMICS
WELL REMOVED TO THE NORTH. SO FAR LOOKS LIKE CLOUDS ASSOCIATED
WITH THE APPROACHING BOUNDARY ARE PREVENTING PATCHY FOG FROM
DEVELOPING THIS MORNING ACROSS INTERIOR AREAS OF SOUTH FLORIDA AND
THAT IS LIKELY TO REMAIN LIKE THAT BUT WILL CONTINUE TO MONITOR
JUST IN CASE. FOR THE MOMENT GIVEN TRENDS LEFT THAT OUT OF THE
FORECAST FOR THIS MORNING.
AHEAD OF THE BOUNDARY TODAY THERE WILL BE ONLY A SLIGHT CHANCE OF A
SHOWER, BEST OVER THE COASTAL WATERS, WITH DRIER AIR MASS
GRADUALLY MOVING IN PARTICULARLY BEGINNING AROUND MID TO LATE
MORNING AND INTO THE EARLY AFTERNOON. YET RAIN CHANCES NOT ENOUGH
TO MENTION IN THE FORECAST. AS ALLUDED TO ABOVE, THE BOUNDARY IS
EXPECTED TO STALL AND DISSIPATE BETWEEN MAINLAND SOUTH FLORIDA AND
THE STRAITS THROUGH TONIGHT. TEMPERATURES WILL CONTINUE TO BE WARM
WITH HIGHS IN THE 70S TODAY...AND THEN INTO THE UPPER 70S TO THE
LOWER 80S BY FRIDAY AND INTO THE WEEKEND. WITH THE DRIER AIR AND
EXCELLENT RADIATIONAL COOLING...OVERNIGHT LOWS TONIGHT MAY GET
INTO THE MID 40S ACROSS THE NORTHWEST INTERIOR. ALSO WITH LIGHT
WINDS AND LOW LEVEL FLOW TURNING FROM THE NORTHEAST, IT IS
POSSIBLE THAT PATCHY FOG DEVELOPS INLAND AROUND LAKE OKEECHOBEE
TONIGHT AND AGAIN FRIDAY NIGHT. HOWEVER, CHANCES OF THAT ARE BEST
FRIDAY NIGHT AS BY THEN RETURN FLOW FROM THE ATLANTIC WOULD HAVE
HAD MORE TIME TO MOISTEN UP THE LOW LEVELS A BIT. BUT GIVEN ALL
MOS GUIDANCE DEVELOP IT TONIGHT ALSO, I PUT IT IN THE GRIDS.
OVERALL TONIGHT WILL BE THE COOLEST NIGHT OF THE COMING WEEK. A
CAVEAT HERE IS THAT THE MET GUIDANCE IS SIGNIFICANTLY WARMER THAN
THE MAV FOR NORTHEAST PORTIONS OF THE AREA (PALM BEACH COUNTY). NAM
IS BANKING ON LOT OF CLOUDS RETURNING QUICKLY WITH LOW LEVEL FLOW
SHIFTING FROM THE NE. BUT AT THIS TIME DECIDED TO STICK WITH MAV.
FLOW WILL NOT BE THAT STRONG AND A LAND BREEZE COULD PREVENT THIS
SCENARIO FROM HAPPENING TOO. EKDMOS ENSEMBLE GUIDANCE ALSO SHOWS A
MEAN IN THE MID TO UPPER 50S.
SO WITH THAT SAID, TEMPS TONIGHT WILL STILL BE A COUPLE OF DEGREES
ABOVE NORMAL ACROSS SOUTH FLORIDA WITH A WARMING TREND IN STORE FOR
THE UPCOMING WEEKEND AND INTO THE FIRST PART OF NEXT WEEK WHEN
MODELS GENERALLY AGREE ON HIGH PRESSURE ALOFT BUILDING FROM THE
SOUTHERN GULF OF MEXICO ACROSS CUBA AND INTO THE BAHAMAS, KEEPING
JET STREAM AND STORM TRACKS WELL TO OUR NORTH. GFS IS THE MOST
AGGRESSIVE OF THE MODELS BUILDING THE AFOREMENTIONED HIGH ALOFT BUT
THE MEAN OF THE ENSEMBLE IS STILL CONSISTENT WITH THE SCENARIO AND
SO IS THE ECMWF. BOTTOM LINE, THE ENSUING WARMING TREND WILL RESULT
IN OVERNIGHT LOWS RUNNING CLOSE TO 10 DEGREES ABOVE NORMAL BY LATE
IN THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK ALONG WITH
DAYTIME HIGHS RUNNING AROUND 5 DEGREES ABOVE NORMAL.
IT WILL REMAIN DRY FOR THE MOST PART THROUGH THE WEEKEND WITH A
SLIGHT CHANCE OF SHOWERS MAY BE COMING BACK INTO THE PICTURE BY THE
EARLY TO MIDDLE PART OF NEXT WEEK AS LOW LEVEL MOISTURE SLOWLY
RETURNS FROM THE SOUTH BUT NOT LOOKING TOO PROMISING AT THIS TIME.
&&
.MARINE...
A BRIEF SURGE IN WIND OF UP TO 15 TO 20 KNOTS TODAY OFF THE COAST
OF PALM BEACH FROM THE NORTH NORTHEAST WILL RESULT IN A SHORT
LIVED SURGE IN SEAS OF UP TO 6 FEET IN THE GULF STREAM. SO WILL
PUT UP A SMALL CRAFT SHOULD EXERCISE CAUTION FOR THOSE WATERS
TODAY. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW 10 TO 15 KNOTS
AND BELOW 4 FEET INTO THE EARLY PART OF NEXT WEEK.
&&
.FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES TODAY WILL BE BELOW 35 PERCENT IN
AREAS NORTH OF ALLIGATOR ALLEY ACROSS NORTHERN COLLIER, HENDRY,
AND GLADES COUNTIES TODAY FOR CLOSE TO 4 HOURS. HOWEVER ERC VALUES
ACROSS THE AREA REMAIN TOO LOW FOR ANY RED FLAG CONCERNS. AFTER
TODAY, LOW LEVEL MOISTURE WILL BE ON THE INCREASE AND SO NO OTHER
FIRE CONCERNS AT THIS TIME INTO EARLY NEXT WEEK AT THE VERY LEAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 55 76 61 / - - - -
FORT LAUDERDALE 75 61 77 66 / - - - -
MIAMI 76 60 77 65 / - - - -
NAPLES 73 52 78 57 / - - - -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...52/PS
AVIATION/RADAR...15/JR
AREA FORECAST DISCUSSION
NWS LINCOLN IL
248 AM CST THU JAN 19 2012
.DISCUSSION...
ISSUED 245 AM CST THU JAN 19 2012
SHARP ARCTIC COLD FRONT IS ABOUT TO MOVE INTO THE NORTHWEST TIP OF
THE CWA AT 08Z...OVERALL EXTENDING FROM EAST CENTRAL WISCONSIN TO
AROUND KANSAS CITY. TEMPERATURES QUICKLY DROP OFF INTO THE SINGLE
DIGITS AS CLOSE AS CENTRAL IOWA. AREA OF LIGHT SNOW SO FAR HAS
MAINLY BEEN BEHIND THE FRONT. UPSTAIRS...VERY TIGHT UPPER FLOW
CONTINUES...WITH EVENING UPPER AIR ANALYSIS SHOWING A SCREAMING
150+ KNOT JET AT 300 MB FROM AROUND SEATTLE SOUTHEAST INTO
MISSOURI.
MAIN FORECAST CHALLENGE WITH THIS PACKAGE IS WITH PRECIPITATION
TYPES FRIDAY AND FRIDAY NIGHT. THE EFFECTS OF THE CURRENT SYSTEM
ARE A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
LATEST HRRR MODEL SWEEPS THE FRONT ACROSS THE CWA THIS MORNING...
LINGERING THROUGH MIDDAY ACROSS THE FAR SOUTHEAST. BEST LIFT WITH
THIS FRONT IS STILL EXPECTED OVER THE NORTHEAST THIRD OF THE
CWA...WITH 1-2 INCHES OF SNOW EXPECTED NORTH OF A BLOOMINGTON TO
DANVILLE LINE THROUGH EARLY AFTERNOON. SHARP SOUTHERN CUTOFF TO
THE SNOW IS EXPECTED...AND WENT WITH ONLY SLIGHT CHANCES SOUTH OF
A JACKSONVILLE TO TERRE HAUTE LINE. ONLY THE SOUTHEAST CWA IS
EXPECTED TO SEE TEMPERATURES RISE ABOVE FREEZING...WITH MOST OF
THE FORECAST AREA SEEING FALLING DAYTIME TEMPERATURES.
THE FRIDAY STORM SYSTEM CONTINUES TO HAVE SEPARATE CONCERNS...ONE
WITH THE SNOW ACROSS THE NORTH IN THE STRONGER LIFT AND BAROCLINIC
ZONE...AND THE POTENTIAL FOR MIXED PRECIPITATION FURTHER SOUTH
CLOSER TO THE SURFACE FEATURES. SNOW-WISE...BEST LIFT STILL
EXPECTED JUST TO OUR NORTH ACROSS NORTHERN ILLINOIS...BUT 2-3
INCHES IS LIKELY AS FAR SOUTH AS GALESBURG AND PEORIA FRIDAY INTO
FRIDAY EVENING. FURTHER SOUTH...FORECAST SOUNDINGS SHOWING A
WEDGE OF WARM AIR AROUND 900 MB MOVING IN LATER FRIDAY AFTERNOON
AND ESPECIALLY DURING THE EVENING. THE NAM IS MOST PRONOUNCED WITH
THIS AROUND CHAMPAIGN AND MATTOON...WHILE THE GFS IS FURTHER SOUTH
TOWARD LAWRENCEVILLE AND THE LOCAL WRF IN BETWEEN. EVAPORATIVE
COOLING WOULD FAVOR MORE OF A SLEET/SNOW MIXTURE INITIALLY...THEN
SOME FREEZING RAIN AND SLEET IN THE EVENING BEFORE SWITCHING OVER
TO SNOW LATE TONIGHT. WILL INCLUDE SOME LOW ICE ACCUMULATIONS IN
AREAS MAINLY BETWEEN I-72 AND I-70...WITH LOCATIONS FROM MATTOON
TO PARIS WITH THE HIGHEST AMOUNTS OF AROUND 0.05 INCH OR SO. MAY
NEED TO CONSIDER WINTER WEATHER ADVISORIES IN SOME PARTS OF THE
CWA...BUT ENOUGH MODEL VARIABILITY EXISTS TO PRECLUDE ISSUING ONE
AT THIS TIME.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
PRECIPITATION TO BE OUT OF THE AREA BEFORE SUNRISE SATURDAY...WITH
HIGH PRESSURE RESULTING IN DRY WEATHER. FOCUS IN THE LONGER TERM
SHIFTS TO A DIGGING SHORTWAVE WHICH WILL CROSS THE MIDDLE OF THE
NATION SUNDAY NIGHT AND MONDAY. FOLLOWED THE SLOWER ECMWF/CANADIAN
SOLUTIONS...WHICH FAVOR RAIN FOR THE MOST PART AND A CHANGEOVER TO
SNOW AS THE PRECIPITATION ENDS SUNDAY NIGHT. MODEL SOLUTIONS ARE
CLOSER TO EACH OTHER ON THE NEXT WAVE WHICH CROSSES MIDWEEK...WITH
THE NEXT SHOT OF PRECIPITATION.
ASIDE FROM THE COLD START TO THE WEEKEND...TEMPERATURES MUCH OF
THIS PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL.
GEELHART
&&
.AVIATION...
ISSUED 1115 PM CST WED JAN 18 2012
TIMING OF COLD FRONT...LIGHT SNOW AND POSSIBLY MVFR CIGS ACROSS
THE TAF SITES THE MAIN FORECAST CONCERN THIS PERIOD. COLD FRONT
HAS PUSHED INTO EAST CENTRAL IOWA...A BIT QUICKER THAN EARLIER
THOUGHT...AND SHOULD NOW APPROACH THE ILLINOIS RIVER VALLEY
BETWEEN 09Z AND 11Z. HAVE SEEN AN INCREASE IN LIGHT SNOW OVER
THE PAST SEVERAL HOURS OVER PARTS OF NORTHEAST IOWA WITH THE IR
SATELLITE LOOP SHOWING AN INCREASE IN COVERAGE OF COLDER CLOUD
TOPS ASSOCIATED WITH THE NEXT UPPER LEVEL WAVE AND STRONG JET
MAX TO OUR WEST.
IT STILL APPEARS MOST OF THE LOWER CIGS AND ANY SNOW WILL BE
BEHIND THE COLD FRONT FOR ABOUT A 4-6 HOUR PERIOD STARTING THURS
MORNING WITH MOST OF THE LOWER CIGS AND SNOW TO OUR EAST BY
20Z...WITH VFR CONDITIONS PREVAILING INTO THURSDAY NIGHT.
ACCUMULATIONS STILL LOOK TO BE AROUND AN INCH NORTH OF A SPI TO
CMI LINE TOMORROW MORNING. SFC WINDS WILL CONTINUE FROM THE SOUTH
AND SOUTHWEST OVERNIGHT AND SWITCH INTO THE NORTHWEST AFTER FROPA
AROUND 10Z AT PIA...BTWN 11Z AND 12Z AT BMI AND SPI...WITH THE
FRONT TO THE EAST OF CMI BY 15Z.
SMITH
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
220 AM MST THU JAN 19 2012
.DISCUSSION...
220 AM MST THU JAN 19 2012
EARLY MORNING WV IMAGERY AND RUC H5 ANALYSIS SHOW BROAD TROUGH
EXTENDING FROM GREAT LAKES ACROSS THE EASTERN US...WITH W/NW FLOW
EXTENDING ACROSS THE CENTRAL PART OF THE COUNTRY. AT THE SURFACE A
STRONG COLD FRONT HAS SETTLED OVER THE CWA...WITH A 20F SPREAD IN
TEMPS BETWEEN THE SW PART OF THE CWA AND THE NE.
TODAY-SATURDAY...WITH DRY CONDITIONS EXPECTED THE MAIN FORECAST
CONCERN WILL CONTINUE TO BE TEMPERATURES AS THE PREVIOUSLY MENTIONED
FRONT AND ASSOCIATED BAROCLINIC ZONE LINGERS ACROSS PORTIONS OF
NORTHWEST KANSAS AND SOUTHWEST NEBRASKA. 30F SPREAD IN HIGH TEMPS
CURRENTLY FORECAST FROM THE EAST TO THE WEST TODAY...WITH AREAS WEST
OF THE FRONT APPROACHING THE MID 50S...AND EAST OF THE FRONT IN THE
MID/UPPER 20S. BETWEEN THESE EXTREMES IT IS DIFFICULT TO PIN DOWN
HIGH TEMPS CONSIDERING THE EXTREME TEMPERATURE GRADIENT THAT
WILL BE IN PLACE...SO HAVE USED A GENERAL BLEND OF PREVIOUS FORECAST
AND LATEST SHORT-RANGE GUIDANCE. TEMPS WILL BEGIN TO MODERATE SOME
ACROSS EASTERN PARTS OF THE AREA FRIDAY...BEFORE A BACKDOOR COLD
FRONT REINFORCES SHALLOW COLD AIR MASS FRIDAY AFTERNOON/EVENING.
SHALLOW COLD AIR MASS BEGINS TO SCOUR OUT WITH TEMPS MODERATING
AHEAD OF SHORTWAVE TROUGH MOVING TOWARDS THE GREAT BASIN...THOUGH
THERE WILL STILL BE A 15-20F GRADIENT FROM EAST TO WEST.
SATURDAY NIGHT...SHORTWAVE TROUGH MOVES TOWARDS THE CENTRAL ROCKIES
SATURDAY NIGHT...WITH INCREASING LARGE SCALE ASCENT OVER THE CWA
AFTER 06Z. NAM/GFS BOTH ARE WEAKER/QUICKER WITH THIS SYSTEM...AND
KEEP CONDITIONS DRY OVER CWA. ECMWF CONTINUES TO SHOW
STRONGER/WETTER SOLUTION. I WAS HESITANT TO JUMP ON THE WET ECMWF
SOLUTION YET...WITH TIMING/STRENGTH STILL IN QUESTION. WITH THE
AMOUNT OF LIFT PRESENT AND LIMITED MOISTURE ADVECTION I COULDNT RULE
OUT SOME FLURRIES IN THE NORTH...BUT WASNT CONFIDENT ENOUGH TO ADD
DURING THIS CYCLE.
DR
FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...RELATIVELY QUIET WEATHER
EXPECTED THROUGH THE ENTIRE PERIOD. A COLD FRONT WILL MOVE THROUGH
THE REGION MONDAY NIGHT AND TUESDAY...HOWEVER PRECIPITATION CHANCES
APPEAR THEY WILL STAY SOUTH AND EAST OF THE LOCAL FORECAST AREA. IT
WILL BRING A PERIOD OF GUSTY NORTH WINDS...PROBABLY TUESDAY
MORNING....AND COOLER TEMPERATURES TUESDAY AND WEDNESDAY...ALBEIT
STILL ABOVE NORMAL.
024
&&
.AVIATION...
957 PM MST WED JAN 18 2012
FOR THE 06Z TAFS...COLD FRONT HAS PUSHED THROUGH KMCK WITH WINDS
FROM THE NORTHEAST. FRONT WILL MEANDER BETWEEN KMCK AND KGLD THIS
PERIOD WITH WINDS SOUTHWESTERLY TO SOUTHERLY AT KGLD AND
EASTERLY TO SOUTHEASTERLY AT KMCK. MODELS HAVE COME INTO BETTER
AGREEMENT WITH LACK OF STRATUS BEHIND THE FRONT...SO HAVE REMOVED
FROM KMCK FOR THIS MORNING. EVEN THOUGH CLOUDS WILL BE PLENTIFUL
THROUGH THE PERIOD...CEILING WILL BE AOA 120-150.
BAS
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1226 AM EST THU JAN 19 2012
UPDATED AVIATION DISCUSSION FOR 06Z TAFS
.SYNOPSIS...
12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WEAK SHRTWV RDGING
IMPACTING THE UPR GRT LKS WITHIN LO AMPLITUDE TROFFING OVER CENTRAL
NAMERICA TO THE S OF CLOSED LO OVER HUDSON BAY. AS OF EARLY THIS
AFTN...THE SUBSIDENCE ASSOCIATED WITH THE SHRTWV RDG HAS ENDED PCPN
EVERYWHERE EXCEPT OVER THE N HALF OF THE KEWEENAW PENINSULA...WHERE
A LO PRES TROF LINGERS TO THE N OF SFC HI PRES IN THE OH RIVER
VALLEY. BUT AS THE FLOW CONTINUES TO BACK TO THE SW BTWN THE
DEPARTING HI TO THE SE AND ANOTHER SHRTWV MOVING E THRU THE NRN
PLAINS...THESE SHSN ARE TENDING TO DRIFT NEWD INTO LK SUP. THE
DISTURBANCE TO THE W IS A POTENT ONE WITH SUPPORTING H5/H3 JET MAX
AND WIND SPEEDS OF 100KT/150KT DIGGING ESEWD THRU THE NW PLAINS.
HOWEVER...SINCE UPSTREAM AIRMASS IS FAIRLY DRY...THE BULK OF THE
PCPN IS FALLING TO THE N OF WARM FNT AND ON THE COLD SIDE OF COLD
FNT ATTENDANT TO SFC LO IN WCNTRL MN. GUSTY NW WINDS UP TO 35-40KTS
ARE DRIVING VERY COLD AIR SEWD INTO THE NRN PLAINS BEHIND THIS LO
AND AHEAD OF VIGOROUS PRES RISE CENTER IN THE DAKOTAS. THE 12Z H85
TEMP AT GREAT FALLS MT WAS -31C.
&&
.SHORT TERM DISCUSSION /TNGT AND THU/...
TNGT...SHRTWV TO THE W IS FCST TO SLIDE ESEWD THRU NRN WI AND INTO
NRN LWR MI BY 12Z THU WHILE SFC LO CENTER SHIFTS ENEWD ACRS THE
KEWEENAW AND INTO ERN LK SUP BY 12Z THU. STRONG SLY FLOW OF H85
TEMPS ARND -12C OFF THE 4C WARM WATERS OF LK MI AHEAD OF THIS
FEATURE INDICATE THERE WL BE ENUF INSTABILITY TO GENERATE LES...
WITH SOME ENHANCEMENT AS DEEP LYR QVECTOR CNVGC/MSTR ASSOCIATED WITH
APRCHG SHRTWV ARRIVE OVHD. 12Z NAM/CNDN MODELS SHOW QPF OF 0.20-0.30
INCH NEAR ERY. CONSIDERING FVRBL OMEGA PROFILE WITHIN DGZ...EXPECT
HI SN/WATER RATIO ARND 25:1 AND UP TO 6 INCHES OF SN E OF ERY. THE
WINDOW OF OPPORTUNITY WL BE RATHER NARROW AS THE FLOW IS PROGGED TO
VEER MORE TO THE WSW OVERNGT...SHIFTING THE HEAVIER SHSN TO THE E.
ISSUED LES ADVY EARLIER TDAY FOR THIS EXPECTED SN. FARTHER
W...FAIRLY DRY ENVIRONMENT AHEAD OF THE COLD FNT AS OBSVD THIS AFTN
SUG THERE WL BE LTL IN THE WAY OF SN UNTIL THE COLD FROPA...ABOUT
03Z OVER THE FAR W AT IWD TO ARND 12Z AT ERY. WITH SHARP THERMAL
GRADIENT/FGEN...SUSPECT THERE WL BE A PERIOD OF SN WITH THE
FROPA...ESPECIALLY NEAR LK SUP WHERE THERE WL BE EXTRA
MOISTENING/UPSLOPE FLOW. OVER THE SCNTRL... EXPECT ONLY SCT -SHSN
WITH MORE DOWNSLOPE FLOW. ALTHOUGH THE SYNOPTIC SN WL CUT OFF
QUICKLY WITH FAST ARRIVAL OF DEEP LYR QVECTOR DVGC/SUBSIDENCE...LES
WL DVLP IN THE STRENGTHENING NW FLOW OF ARCTIC AIR LEFT IN THE WAKE
OF DEPARTING LO. H85 TEMPS ARE PROGGED TO PLUMMET TO ARND -25C AT
IWD BY 12Z THU. ANOTHER SGNFT FEATURE TNGT WL BE STRENGTHENING NW
FLOW ASSOCIATED WITH STRONG CAD/IN ADVANCE OF APRCHG PRES RISE
CENTER THAT IS FCST TO REACH THE W TOWARD 12Z. PREFER THE STRONGER
H925 WINDS UP TO 40-45KTS SHOWN BY THE 12Z GFS/LOCAL WRF-ARW RUNS
GIVEN THE STRENGTH OF THIS DISTURBANCE...AND THESE WINDS WL MIX
EFFICIENTLY TO THE SFC WITH VIGOROUS CAD. THE COMBINATION OF THE
STRONG WINDS AND FALLING TEMPS WL PUSH WIND CHILLS AS LO AS -20 TO
-25F OVER GOGEBIC COUNTY.
THU...GUSTY NW WINDS/VIGOROUS CAD WITH H85 TEMPS FALLING TO ARND
-25C AND STRONG SUBSIDENCE/DEEP LYR QVECTOR DVGC WL BE IN PLACE
BEHIND THE DEPARTING SFC LO/UPR DISTURBANCE AT DAYBREAK. EXPECT THE
WINDS TO DIMINISH THU AFTN FOLLOWING PASSAGE OF PRES RISE CENTER TO
THE E AFT 18Z. WITH THE SLOW APRCH OF HI PRES FM THE W...MODEL FCST
SDNGS SHOW THE INVRN BASE AT IWD SINKING TO AOB 3K FT AGL BY LATE IN
THE DAY AS WINDS BACK MORE TO THE W...DIMINISHING THE PCPN IN THAT
AREA. THIS FLOW WL REMAIN FAVORABLE FOR AREAS FARTHER TO THE N THRU
THE KEWEENAW...MAINTAINING HIER INVRN HGTS. EXPECT LES TO INTENSIFY
OVER THE E WITH ENHANCED LLVL CNVGC PERSISTING AT THE END OF LONG NW
FETCH OVER THE OPEN WATERS OF LK SUP. WITH INVRN BASE FCST ARND 5K
FT AGL OVER THE KEWEENAW AND OVER THE E...LES CHART SUGS UP TO 6
INCHES OF SN PER 12 HR PERIOD. ALTHOUGH THESE AMOUNTS MAY NOT EASILY
EXCEED WARNING THRESHOLDS...THE ARRIVAL OF MUCH COLDER AIR THAT
DROPS H85 TEMPS TO ARND -25C AND THE DGZ ALMOST TO THE SFC OVER THE
W AS WELL AS THE GUSTY WINDS WL HAMPER SN GROWTH...LEADING TO
SMALLER SN FLAKES. WITH GUSTY WINDS...EXPECT EFFICIENT REDUCTION IN
VSBY THAT JUSTIFIES GOING WITH WRNGS IN MOST COUNTIES EXCEPT FOR
GOGEBIC COUNTY...WHICH WL NOT BE AS EXPOSED TO THE STRONG WINDS.
WITH THE INFLUX OF COLD AIR...TEMPS WL BE STEADY OR SLOWLY FALLING
THRU THE DAY.
.LONG TERM /00Z FRI THROUGH NEXT WED/...
THURSDAY NIGHT INTO FRI...NW LES WILL BE ONGOING AT THE START OF THE
PERIOD...BUT INTENSITY SHOULD BE LIGHTER THAN THU MORNING AS DRY AIR
AND SUBSIDENCE ALOFT LOWERS INVERSION HEIGHTS TOWARDS 4-5KFT.
A SECONDARY SURGE OF LLVL MOISTURE WILL ARRIVE TOWARDS MIDNIGHT AS
MID LVL RIDGING SLIDES TO THE E OF THE AREA. THIS ADDITIONAL
MOISTURE BOOSTS THE INVERSION HEIGHTS TO 5-6KFT BY 06Z. AS THE HIGH
MOVES FARTHER SE AND A WEAK TROUGH SLIDES OVER NRN LAKE
SUPERIOR...LOW LEVEL FLOW WILL BECOME MORE FROM THE WSW. 850MB TEMPS
WILL WARM SOME TO AROUND -22C...WHICH PLACES MORE OF THE DGZ IN THE
BEST LIFT. THIS IS ALSO NOTED BY THE LAKE EFFECT SNOW PARAMETER
INCREASING TO AROUND 0.75 OVER THE KEWEENAW BY 03Z FRI. THE BACKING
WINDS WILL TEND TO FAVOR A STRONGER LES BAND FOCUSING SOMEWHERE OVER
NWRN UPPER MI FROM NEAR ONTONAGON INTO THE KEWEENAW...AND SHOULD
MOVE N THROUGH THE DAY AS WINDS BECOME MORE SWLY. LIKELY POPS FROM
THE PREVIOUS FORECAST LOOK GOOD...SO WILL MAKE MINOR TREAKS TO THOSE
GRIDS. ONGOING MULTI BANDED LES OVER ERN UPPER MI WILL MOVE OFFSHORE
BY 18Z FRI AS WINDS BECOME SWLY...BUT THERE MAY BE A PERIOD OF
STRONGER SNOW DUE TO CONVERGENCE AS WINDS BACK...BUT THAT MAY STAY
JUST OFFSHORE AS WELL.
WENT WITH THE LOW END OF GUIDANCE FOR TEMPS THU NIGHT. COLD...DRY
AIR AND DECREASING WINDS WILL BRING LOW TEMPS DOWN TO NEAR -20 OVER
THE INTERIOR WEST. WINDS WILL BE LIGHT AT AROUND 5KTS...BUT WIND
CHILLS WILL STILL FALL TO AROUND -30. CONTINUED TO HIGHLIGHT THIS
THREAT IN THE HWO. HIGHS WILL BE IN THE TEENS FRI.
AN UPPER SHORTWAVE MOVES TO OUR S FRI AFTERNOON...LEADING TO SOME
PRECIP SKIRTING THE SRN CWA. AT THIS TIME...THE MENOMINEE AREA LOOKS
TO GET THE MOST SNOW FROM THIS SYSTEM...BUT WOULD BE AN INCH AT
MOST. IF THE SYSTEM ENDS UP MOVING FARTHER N...SNOWFALL TOTALS WOULD
BE HIGHER.
SATURDAY...MODELS START TO DIVERGE ON SOLUTIONS AT THIS
POINT...ALTHOUGH NOT DRASTICALLY...YET. MAIN DIFFERENCES COME FROM
THE TIMING OF SFC RIDGING MOVING THROUGH. THE GFS IS ON THE SLOWER
END OF GUIDANCE...WITH THE RIDGE AXIS OF THE CWA AT 18Z SAT. THE
ECMWF IS FASTER...WITH THE AXIS OVER THE CWA AT 12Z SAT. THE BIG
DIFFERENCE FROM THIS IS WITH WIND DIRECTIONS. AHEAD OF THE RIDGE
AXIS...WINDS LOOK TO BE MORE NWLY...WHICH WOULD BRING SOME LIGHT LES
NEAR LAKE SUPERIOR E OF MUNISING. WILL GO WITH A MORE BLENDED
SOLUTION RIGHT NOW...WITH THE GREATEST POPS IN NW FLOW AREAS LATE
FRI NIGHT/SAT MORN. HIGHS WILL BE IN THE TEENS TO LOW 20S SAT.
SAT NIGHT THROUGH WED...A SERIES OF UPPER LEVEL DISTURBANCES
MOVES THROUGH DURING THIS TIME...BUT MODELS ARE HAVING A HARD TIME
HANDLING THESE SYSTEMS. NOT ONLY IS MODEL AGREEMENT POOR...RUN TO
RUN DISCONTINUITY IS ALSO A PROBLEM DURING THIS TIME. THESE FACTORS
LEAD TO WELL BELOW NORMAL CONFIDENCE IN THIS PART OF THE FORECAST.
OVERALL...STUCK WITH CONSENSUS MODEL BLENDS FOR THIS PERIOD.
THE GENERAL FEEL FROM THE MODELS IS THAT A LOW PRESSURE SYSTEM WILL
MOVE INTO THE NRN PLAINS SAT NIGHT INTO SUN. THIS LEADS TO
INCREASING TEMPS IN THE SW FLOW WAA REGIME AHEAD OF THE SYSTEM. THE
BEST CHANCE FOR PRECIP CURRENLTY LOOKS TO BE SAT NIGHT INTO
SUN...BUT AS STATED BEFORE CONFIDENCE IS LIMITED.
A PERIOD OF DRIER WEATHER WILL PROBABLY RESULT LATE MON OR TUE AS
UPPER LEVEL RIDGING MOVES OVER THE CWA. MODELS THEN SHOW A SHARP
UPPER TROUGH MOVING TO THE CENTRAL CONUS WED...WHICH WOULD RESULT IN
PRECIP OVER PARTS OF THE REGION.
&&
.AVIATION /FOR THE 06Z TAF ISSUANCE/...
BEHIND AN ARCTIC COLD FRONT OVERNIGHT...NORTHWEST WINDS WILL
INCREASE AT ALL THREE SITES...FAVORING MDT/HVY LES AT IWD AND CMX.
THE COMBINATION OF HEAVY LES AND STRONGER WINDS WILL SIGNIFICANTLY
REDUCE VIS AT CMX DURING THE OVERNIGHT HOURS. LES SHOULD BEGIN TO
EASE SLIGHTLY AROUND 18Z ON THURSDAY AS WINDS BEGIN TO BACK TO THE
WEST AND DRIER AIR MOVES INTO THE AREA. EXPECT CONDITIONS TO IMPROVE
TO VFR BY LATE AFTERNOON AT KSAW/KIWD AS A RIDGE BUILDS INTO THE
AREA AND WINDS BACK WSW. HOWEVER...A MORE FAVORABLE TRAJECTORY
ACROSS LAKE SUPERIOR WILL LIKELY BRING HEAVIER LAKE EFFECT SNOW
SHOWERS BACK INTO KCMX DURING THE EVENING.
&&
.MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/...
GOING S GALES UP TO 35 KTS OVER ERN LK SUP THIS EVNG STILL APPEAR ON
TRACK WITH SHARPENING PRES GRADIENT/AREA OF PRES FALLS PASSING TO
THE N. AS THE SFC LO PASSES W-E LATE TNGT INTO THU...EXPECT SHARP
WSHFT TO THE NW. INFLUX OF BITTERLY COLD AIR WILL ENHANCE MIXING OF
WINDS UP TO 40-45 KTS JUST ABOVE THE SURFACE...GALES WILL DEVELOP IN
MOST AREAS. WITH HI WAVES AS WELL...EXPECT HEAVY FREEZING SPRAY OVER
THE ENTIRE LAKE. THE STRONGEST WINDS WILL TEND TO DIMINISH ON THU
AFTERNOON. HIGH PRESSURE WILL BRIEFLY MOVE THROUGH THURSDAY NIGHT
BEFORE A WEAK LOW PRESSURE SYSTEM MOVES OVER LAKE SUPERIOR ON FRIDAY.
HIGH PRESSURE WILL RETURN ON SATURDAY...THEN WILL MOVE EAST SATURDAY
NIGHT AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. THIS LOW PRESSURE
SYSTEM LOOKS TO MOVE INTO THE AREA SUNDAY NIGHT INTO MONDAY BEFORE
MOVING EAST MONDAY NIGHT. THERE IS STILL A LARGE AMOUNT OF
UNCERTAINTY WITH THE TRACK OF THIS SYSTEM.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
UPPER MICHIGAN...
LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ084.
LAKE EFFECT SNOW WARNING FROM 7 AM THIS MORNING TO 1 AM EST
FRIDAY FOR MIZ006-007-085.
LAKE EFFECT SNOW WARNING UNTIL 7 AM EST FRIDAY FOR MIZ001-003.
LAKE EFFECT SNOW ADVISORY UNTIL NOON CST THURSDAY FOR MIZ009.
LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ007.
LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ002.
LAKE SUPERIOR...
HEAVY FREEZING SPRAY WARNING FROM 7 AM THIS MORNING TO 7 AM EST
FRIDAY FOR LSZ243>251-264>267.
GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266-267.
GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ249>251-264-265.
GALE WARNING UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR LSZ162-
263.
GALE WARNING FROM 7 AM THIS MORNING TO 1 PM EST THIS AFTERNOON
FOR LSZ242>245-248.
HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ FRIDAY
FOR LSZ162-240>242-263.
GALE WARNING UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR LSZ240-
241.
LAKE MICHIGAN...
HEAVY FREEZING SPRAY WARNING UNTIL 4 PM EST THIS AFTERNOON FOR
LMZ221-248-250.
GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LMZ221-248-250.
&&
$$
SYNOPSIS...KC
SHORT TERM...KC
LONG TERM...TITUS
AVIATION...JLB
MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
1113 PM CST WED JAN 18 2012
.AVIATION...
LOW CONFIDENCE ON WIND GUSTS REACHING 40 KNOTS OR HIGHER AT THE
AMARILLO TAF SITE TONIGHT. IT APPEARS THAT THE STRONGEST WINDS WILL
REMAIN WEST OF THE AMARILLO TAF SITE. THEREFORE...WILL CARRY WESTERLY
WINDS 15 TO 25 OR 30 KNOTS WITH HIGHER GUSTS BRIEFLY UNTIL AROUND 08Z
TO 10Z THURSDAY AT AMARILLO. OTHERWISE...SOUTHWESTERLY TO WESTERLY
WINDS 10 TO 20 KNOTS TONIGHT. WEAK BACKDOOR COLD FRONT WILL AFFECT
THE GUYMON TAF SITE THURSDAY CAUSING THE WINDS TO BECOME
SOUTHEASTERLY TO NORTHEASTERLY 5 TO 15 KNOTS AFTER 15Z THURSDAY. AT
THE DALHART AND AMARILLO TAF SITES...WINDS WILL BECOME MORE SOUTHERLY
OR SOUTHWESTERLY 5 TO 15 KNOTS AFTER 16Z TO 20Z THURSDAY.
CONSIDERABLE HIGH LEVEL CLOUDINESS WILL ALLOW VFR CONDITIONS TO PREVAIL.
SCHNEIDER
&&
.PREV DISCUSSION... /ISSUED 1005 PM CST WED JAN 18 2012/
UPDATE...
MAIN CHANGE WAS TO LOWER WIND SPEEDS TONIGHT...MAINLY ACROSS THE
WESTERN AND SOUTHWESTERN TEXAS PANHANDLE.
DISCUSSION...
STILL A LOW CONFIDENCE FORECAST WITH RESPECT TO WIND SPEEDS
OVERNIGHT. TUCUMCARI WIND PROFILER DATA INDICATES 0-1 KM FLOW HAS
INCREASED SUBSTANTIALLY OVER THE LAST FEW HOURS IN RESPONSE TO
STRENGTHENING LOW-LEVEL JET. SOME OF THIS HIGHER MOMENTUM AIR
IS BEING MIXED TO THE GROUND AS EVIDENCED BY RECENT OBSERVATIONS AT
KTCC. IT APPEARS THAT THE LOW-LEVEL JET IS BEGINNING TO EXPAND
EASTWARD AS HEREFORD HAS RECENTLY REPORTED GUSTS UP TO 26 MPH.
LATEST NAM...HRRR...AND RUC GUIDANCE CONTINUE TO SUGGEST THE
STRONGEST WINDS WILL REMAIN SOUTH AND WEST OF A LINE FROM DALHART TO
CLARENDON. BOTH THE RUC AND NAM SHOW THE 0-1 KM FLOW WILL BE 30-40
KT ACROSS THESE AREAS THROUGH 3 AM. HOWEVER...THE RUC REMAINS THE
MOST AGGRESSIVE WITH THE WIND POTENTIAL OVERNIGHT...MAINLY DUE TO
KEEPING THE NEAR-GROUND LAYER MIXED AND ALLOWING THE HIGHER MOMENTUM
AIR TO BE TRANSPORTED DOWNWARD. THE NAM LARGELY KEEPS THE BOUNDARY
LAYER DECOUPLED AND IS MUCH WEAKER WITH 0-1 KM LAPSE RATES. AM
SOMEWHAT CONCERNED THAT SURFACE TEMPERATURES ACROSS EASTERN NEW
MEXICO AND PARTS OF OLDHAM AND DEAF SMITH COUNTIES HAVE INCREASED
WITHIN THE LAST HOUR. THIS SUGGESTS THAT THE NEAR-GROUND LAYER IS
REMAINING MIXED AND THE RUC COULD BE ONTO SOMETHING. IF THE RUC
VERIFIES...COULD SEE WINDS 25-35 MPH WITH GUSTS TO 45 MPH ACROSS THE
SOUTHWESTERN TEXAS PANHANDLE. HOWEVER...BOTH THE NAM AND HRRR SUGGEST
VERY LITTLE MIXING OVERNIGHT...WHICH SHOULD KEEP WINDS 20-25 MPH WITH
GUSTS UP TO 35 MPH. ADDITIONALLY...LATEST MET GUIDANCE...WHICH HAD
PREVIOUSLY BEEN AGGRESSIVE WITH THE WINDS...HAS BACKED OFF
SIGNIFICANTLY. LEANED MORE HEAVILY TOWARDS THE NAM...HRRR...AND
LATEST MET GUIDANCE...SO WE LOWERED WIND SPEEDS. STILL NOT EXPECTING
WINDS TO BE STRONG ENOUGH TO REACH ADVISORY CRITERIA...BUT IT COULD
STILL BE BREEZY TO WINDY AT TIMES THROUGH 3 AM. UPDATED PRODUCTS
HAVE BEEN SENT.
JACKSON
PREV DISCUSSION... /ISSUED 540 PM CST WED JAN 18 2012/
AVIATION...
BIGGEST AVIATION CONCERN WILL BE WIND SPEEDS TONIGHT...MAINLY BETWEEN
03Z AND 09Z THURSDAY. WINDS JUST ABOVE THE SURFACE EXPECTED TO
INCREASE FROM THE WEST TO AROUND 40 TO 50 KNOTS BETWEEN 03Z AND 09Z
THURSDAY...AND THE TUCUMCARI PROFILER SHOWED A 10 KNOT JUMP IN WIND
SPEEDS BETWEEN 22Z AND 23Z WEDNESDAY AROUND THE THIRD AND FOURTH
GATES. THE MAIN CONCERN WILL BE THE AMARILLO TAF WHERE SOME 40 KNOT
OR HIGHER GUST MAY OCCUR JUST PRIOR TO 06Z THURSDAY...AND JUST AFTER
06Z THURSDAY. MAY NEED AN AVIATION WEATHER ADVISORY FOR THE AMARILLO
AIRPORT TONIGHT FOR A BRIEF WINDOW...HOWEVER CONFIDENCE JUST A BIT
TOO LOW AT THE MOMENT TO ISSUE. WILL CONTINUE TO MONITOR CLOSELY.
OTHERWISE...VFR CONDITIONS WITH HIGH LEVEL CLOUDINESS THROUGH 00Z
FRIDAY. WESTERLY TO SOUTHWESTERLY AND SOUTHERLY WINDS 10 TO 20
KNOTS WITH SOME HIGHER GUSTS POSSIBLE...THE EXCEPTION BEING BETWEEN
03Z AND 09Z THURSDAY AT THE AMARILLO TAF SITE.
SCHNEIDER
PREV DISCUSSION... /ISSUED 359 PM CST WED JAN 18 2012/
DISCUSSION...
FOCUS OF THIS FORECAST REMAINS ON TEMPERATURES THROUGH THE
WEEKEND...THEN SHIFTS TO PRECIPITATION PROSPECTS EARLY NEXT WEEK.
A STRONG UPPER JET STRETCHED FROM THE PAC NW SOUTHEAST ACROSS THE
NORTHERN ROCKIES INTO THE CENTRAL PLAINS THIS AFTERNOON. LEE ENHANCED
CIRRUS ON THE SOUTH SIDE OF THE JET HAS PRODUCED A CIRRUS CANOPY
ACROSS THE PANHANDLES TODAY...WHICH HAS BEEN FAIRLY THICK AT TIMES.
THIS HAS DELAYED THE WARMUP TO SOME DEGREE TODAY...BUT A STEADY CLIMB
THROUGH THE DAY HAS ALLOWED TEMPS TO REACH THE MID 50S TO LOWER 60S
LATE THIS AFTERNOON. WEST/SOUTHWEST DOWNSLOPE WINDS TO THE EAST OF A
LEE SURFACE TROUGH OVER EASTERN CO/NM HAVE AIDED THE WARMUP.
A BREEZY TO WINDY AND RATHER MILD NIGHT FOR JANUARY IS EXPECTED FOR
THE PANHANDLES TONIGHT. THE SURFACE TROUGH WILL ADVANCE EAST ACROSS
THE AREA TONIGHT...SETTING UP A DECENT PRESSURE GRADIENT ACROSS
WESTERN AND CENTRAL PORTIONS OF THE CWA. A WESTERLY 50 KT LLJ IS ALSO
PROGGED TONIGHT. THUS...EXPECT BREEZY TO WINDY CONDITIONS THIS
EVENING AND OVERNIGHT ACROSS WESTERN AND CENTRAL AREAS...WHICH WILL
KEEP TEMPS UP. HAVE THUS GONE SEVERAL DEGREES ABOVE MOS GUIDANCE WITH
FORECAST LOWS. CIRRUS MAY ALSO HOLD TEMPS UP A TAD...ALTHOUGH IT IS
EXPECTED TO THIN LATER TONIGHT. WINDS WILL BE LIGHTER AND TEMPS
COOLER ACROSS EASTERN AREAS MORE WITHIN THE SURFACE TROUGH AXIS.
A COLD FRONT WILL BACK ITS WAY INTO THE AREA ON THURSDAY...SETTING UP
A FAIRLY STRONG SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT OF ABOUT
20 DEGREES ACROSS THE CWA. THE PRESSURE GRADIENT WILL ALSO RELAX WITH
THIS BOUNDARY PUSHING INTO THE AREA. WINDS MAY BE BREEZY ACROSS THE
WEST/SOUTHWEST IN THE MORNING...BUT SHOULD DISSIPATE IN THE
AFTERNOON.
A ZONAL FLOW ALOFT WILL BE IN PLACE ACROSS THE CONUS ON FRIDAY. A
FAST-MOVING MID/UPPER-LEVEL SHORTWAVE WILL MOVE EAST ACROSS THE
CENTRAL PLAINS AND CLIP THE PANHANDLES FRIDAY AFTERNOON AND
EVENING...SENDING A WEAK COLD FRONT SOUTH DURING THIS TIME AS WELL.
STILL SOME SUBTLE TIMING DIFFERENCES WITH THE SHORTWAVE AND
FRONT...WHICH ISN/T SURPRISING CONSIDERING THE FAST ZONAL FLOW. WILL
SEE BREEZY TO WINDY WEST WINDS SOUTH OF THE FRONT...WITH WINDS
DECREASING AND TURNING TO THE NORTH IN ITS WAKE. FRONTAL TIMING MAKES
FOR A TRICKY TEMPERATURE FORECAST...BUT WILL AIM FOR LOWER 50S
NORTHEAST TO AROUND 70F IN THE FAR SOUTH FOR NOW. LOW-LEVELS APPEAR
WAY TOO DRY FOR THE SHORTWAVE TO SQUEEZE OUT ANY PRECIP.
LEE TROUGHING WILL QUICKLY RE-DEVELOP ON SATURDAY BENEATH A CONTINUED
ZONAL FLOW ALOFT. SOUTH/SOUTHWEST WINDS WILL RETURN IN RESPONSE...AND
UNSEASONABLY WARM CONDITIONS WILL CONTINUE. ANOTHER SHORTWAVE WILL
MOVE ACROSS SATURDAY NIGHT/SUNDAY...SENDING ANOTHER WEAK COLD FRONT
THROUGH. AGAIN...THIS WAVE LOOKS TO BE MOISTURE STARVED AND THE FRONT
WILL HAVE LITTLE EFFECT ON TEMPERATURES. WARM...DRY CONDITIONS TO
PERSIST THROUGH MONDAY AHEAD OF THE NEXT UPPER TROUGH WORKING ACROSS
THE WEST.
THERE REMAINS QUITE A BIT OF UNCERTAINTY REGARDING THE POTENTIAL
SYSTEM FOR EARLY TO MID NEXT WEEK. MODEL SOLUTIONS CONTINUE TO WAVER
BETWEEN A CLOSED LOW AND A PROGRESSIVE OPEN WAVE AFFECTING THE
PANHANDLES CENTERED ON THE TUESDAY TIMEFRAME. LATEST 12Z RUNS OF THE
GFS AND ECMWF ARE BOTH NOW ADVERTISING AN OPEN WAVE AND ONLY MINIMAL
PRECIPITATION CHANCES. WILL MAINTAIN SOME SMALL POPS TUESDAY
ATTM...AND SEE HOW LATER RUNS TREND. DID WARM TEMPS SLIGHTLY ON
TUESDAY AND TRIMMED THE RAIN/SNOW MIX BACK TO THE NORTHWEST. DRY BUT
COOLER CONDITIONS THEN EXPECTED WEDNESDAY BEHIND THE DEPARTING UPPER
TROUGH/LOW.
KB
FIRE WEATHER...
A COLD FRONT WILL BACK INTO THE EASTERN OKLAHOMA PANHANDLE AND
NORTHEAST TEXAS PANHANDLE ON THURSDAY...SETTING UP A SOUTHWEST TO
NORTHEAST TEMPERATURE GRADIENT ACROSS THE AREA. THIS FRONT WILL ALSO
KEEP WINDS LIGHTER...WITH SPEEDS EXPECTED TO REMAIN BELOW 15 MPH.
THUS...ELEVATED FIRE WEATHER CONDITIONS ARE NOT EXPECTED DESPITE
AFTERNOON RELATIVE HUMIDITIES FALLING TO 15 TO 20 PERCENT ACROSS THE
SOUTHWEST HALF OF THE PANHANDLES. UNSEASONABLY WARM TEMPERATURES WILL
CONTINUE INTO FRIDAY. WESTERLY WINDS WILL INCREASE AHEAD OF THE NEXT
COLD FRONT...WHICH IS EXPECTED TO MOVE THROUGH DURING THE AFTERNOON
OR EVENING HOURS. ELEVATED FIRE WEATHER CONDITIONS WILL BE POSSIBLE
ACROSS THE SOUTHWEST HALF OF THE AREA...WITH CRITICAL CONDITIONS
POSSIBLE ACROSS THE SOUTHWEST AND SOUTH CENTRAL TEXAS PANHANDLE WHERE
WESTERLY WINDS WILL INCREASE TO 20 TO 30 MPH WITH HIGHER GUSTS AND
MINIMUM RELATIVE HUMIDITIES WILL FALL TO 15 TO 20 PERCENT. A FIRE
WEATHER WATCH HAS BEEN ISSUED FOR THESE AREAS. THERE IS STILL SOME
UNCERTAINTY REGARDING TIMING OF THE COLD FRONT...AND A FASTER ARRIVAL
COULD POTENTIALLY EASE FIRE WEATHER CONCERNS WHILE A SLOWER ARRIVAL
MAY ALLOW CRITICAL CONDITIONS TO DEVELOP OVER A LARGER AREA.
UNSEASONABLY WARM CONDITIONS WILL CONTINUE OVER THE WEEKEND INTO
MONDAY. COMBINED WITH BREEZY CONDITIONS...ELEVATED FIRE WEATHER
CONDITIONS WILL BE POSSIBLE SATURDAY THROUGH MONDAY ACROSS WESTERN
AND CENTRAL PORTIONS OF THE AREA.
KB
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DEAF SMITH...
OLDHAM...POTTER...RANDALL.
OK...NONE.
&&
$$
11/13
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
1005 PM CST WED JAN 18 2012
.UPDATE...
MAIN CHANGE WAS TO LOWER WIND SPEEDS TONIGHT...MAINLY ACROSS THE
WESTERN AND SOUTHWESTERN TEXAS PANHANDLE.
&&
.DISCUSSION...
STILL A LOW CONFIDENCE FORECAST WITH RESPECT TO WIND SPEEDS
OVERNIGHT. TUCUMCARI WIND PROFILER DATA INDICATES 0-1 KM FLOW HAS
INCREASED SUBSTANTIALLY OVER THE LAST FEW HOURS IN RESPONSE TO
STRENGTHENING LOW-LEVEL JET. SOME OF THIS HIGHER MOMENTUM AIR
IS BEING MIXED TO THE GROUND AS EVIDENCED BY RECENT OBSERVATIONS AT
KTCC. IT APPEARS THAT THE LOW-LEVEL JET IS BEGINNING TO EXPAND
EASTWARD AS HEREFORD HAS RECENTLY REPORTED GUSTS UP TO 26 MPH.
LATEST NAM...HRRR...AND RUC GUIDANCE CONTINUE TO SUGGEST THE
STRONGEST WINDS WILL REMAIN SOUTH AND WEST OF A LINE FROM DALHART TO
CLARENDON. BOTH THE RUC AND NAM SHOW THE 0-1 KM FLOW WILL BE 30-40
KT ACROSS THESE AREAS THROUGH 3 AM. HOWEVER...THE RUC REMAINS THE
MOST AGGRESSIVE WITH THE WIND POTENTIAL OVERNIGHT...MAINLY DUE TO
KEEPING THE NEAR-GROUND LAYER MIXED AND ALLOWING THE HIGHER MOMENTUM
AIR TO BE TRANSPORTED DOWNWARD. THE NAM LARGELY KEEPS THE BOUNDARY
LAYER DECOUPLED AND IS MUCH WEAKER WITH 0-1 KM LAPSE RATES. AM
SOMEWHAT CONCERNED THAT SURFACE TEMPERATURES ACROSS EASTERN NEW
MEXICO AND PARTS OF OLDHAM AND DEAF SMITH COUNTIES HAVE INCREASED
WITHIN THE LAST HOUR. THIS SUGGESTS THAT THE NEAR-GROUND LAYER IS
REMAINING MIXED AND THE RUC COULD BE ONTO SOMETHING. IF THE RUC
VERIFIES...COULD SEE WINDS 25-35 MPH WITH GUSTS TO 45 MPH ACROSS THE
SOUTHWESTERN TEXAS PANHANDLE. HOWEVER...BOTH THE NAM AND HRRR SUGGEST
VERY LITTLE MIXING OVERNIGHT...WHICH SHOULD KEEP WINDS 20-25 MPH WITH
GUSTS UP TO 35 MPH. ADDITIONALLY...LATEST MET GUIDANCE...WHICH HAD
PREVIOUSLY BEEN AGGRESSIVE WITH THE WINDS...HAS BACKED OFF
SIGNIFICANTLY. LEANED MORE HEAVILY TOWARDS THE NAM...HRRR...AND
LATEST MET GUIDANCE...SO WE LOWERED WIND SPEEDS. STILL NOT EXPECTING
WINDS TO BE STRONG ENOUGH TO REACH ADVISORY CRITERIA...BUT IT COULD
STILL BE BREEZY TO WINDY AT TIMES THROUGH 3 AM. UPDATED PRODUCTS
HAVE BEEN SENT.
JACKSON
&&
.PREV DISCUSSION... /ISSUED 540 PM CST WED JAN 18 2012/
AVIATION...
BIGGEST AVIATION CONCERN WILL BE WIND SPEEDS TONIGHT...MAINLY BETWEEN
03Z AND 09Z THURSDAY. WINDS JUST ABOVE THE SURFACE EXPECTED TO
INCREASE FROM THE WEST TO AROUND 40 TO 50 KNOTS BETWEEN 03Z AND 09Z
THURSDAY...AND THE TUCUMCARI PROFILER SHOWED A 10 KNOT JUMP IN WIND
SPEEDS BETWEEN 22Z AND 23Z WEDNESDAY AROUND THE THIRD AND FOURTH
GATES. THE MAIN CONCERN WILL BE THE AMARILLO TAF WHERE SOME 40 KNOT
OR HIGHER GUST MAY OCCUR JUST PRIOR TO 06Z THURSDAY...AND JUST AFTER
06Z THURSDAY. MAY NEED AN AVIATION WEATHER ADVISORY FOR THE AMARILLO
AIRPORT TONIGHT FOR A BRIEF WINDOW...HOWEVER CONFIDENCE JUST A BIT
TOO LOW AT THE MOMENT TO ISSUE. WILL CONTINUE TO MONITOR CLOSELY.
OTHERWISE...VFR CONDITIONS WITH HIGH LEVEL CLOUDINESS THROUGH 00Z
FRIDAY. WESTERLY TO SOUTHWESTERLY AND SOUTHERLY WINDS 10 TO 20
KNOTS WITH SOME HIGHER GUSTS POSSIBLE...THE EXCEPTION BEING BETWEEN
03Z AND 09Z THURSDAY AT THE AMARILLO TAF SITE.
SCHNEIDER
PREV DISCUSSION... /ISSUED 359 PM CST WED JAN 18 2012/
DISCUSSION...
FOCUS OF THIS FORECAST REMAINS ON TEMPERATURES THROUGH THE
WEEKEND...THEN SHIFTS TO PRECIPITATION PROSPECTS EARLY NEXT WEEK.
A STRONG UPPER JET STRETCHED FROM THE PAC NW SOUTHEAST ACROSS THE
NORTHERN ROCKIES INTO THE CENTRAL PLAINS THIS AFTERNOON. LEE ENHANCED
CIRRUS ON THE SOUTH SIDE OF THE JET HAS PRODUCED A CIRRUS CANOPY
ACROSS THE PANHANDLES TODAY...WHICH HAS BEEN FAIRLY THICK AT TIMES.
THIS HAS DELAYED THE WARMUP TO SOME DEGREE TODAY...BUT A STEADY CLIMB
THROUGH THE DAY HAS ALLOWED TEMPS TO REACH THE MID 50S TO LOWER 60S
LATE THIS AFTERNOON. WEST/SOUTHWEST DOWNSLOPE WINDS TO THE EAST OF A
LEE SURFACE TROUGH OVER EASTERN CO/NM HAVE AIDED THE WARMUP.
A BREEZY TO WINDY AND RATHER MILD NIGHT FOR JANUARY IS EXPECTED FOR
THE PANHANDLES TONIGHT. THE SURFACE TROUGH WILL ADVANCE EAST ACROSS
THE AREA TONIGHT...SETTING UP A DECENT PRESSURE GRADIENT ACROSS
WESTERN AND CENTRAL PORTIONS OF THE CWA. A WESTERLY 50 KT LLJ IS ALSO
PROGGED TONIGHT. THUS...EXPECT BREEZY TO WINDY CONDITIONS THIS
EVENING AND OVERNIGHT ACROSS WESTERN AND CENTRAL AREAS...WHICH WILL
KEEP TEMPS UP. HAVE THUS GONE SEVERAL DEGREES ABOVE MOS GUIDANCE WITH
FORECAST LOWS. CIRRUS MAY ALSO HOLD TEMPS UP A TAD...ALTHOUGH IT IS
EXPECTED TO THIN LATER TONIGHT. WINDS WILL BE LIGHTER AND TEMPS
COOLER ACROSS EASTERN AREAS MORE WITHIN THE SURFACE TROUGH AXIS.
A COLD FRONT WILL BACK ITS WAY INTO THE AREA ON THURSDAY...SETTING UP
A FAIRLY STRONG SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT OF ABOUT
20 DEGREES ACROSS THE CWA. THE PRESSURE GRADIENT WILL ALSO RELAX WITH
THIS BOUNDARY PUSHING INTO THE AREA. WINDS MAY BE BREEZY ACROSS THE
WEST/SOUTHWEST IN THE MORNING...BUT SHOULD DISSIPATE IN THE
AFTERNOON.
A ZONAL FLOW ALOFT WILL BE IN PLACE ACROSS THE CONUS ON FRIDAY. A
FAST-MOVING MID/UPPER-LEVEL SHORTWAVE WILL MOVE EAST ACROSS THE
CENTRAL PLAINS AND CLIP THE PANHANDLES FRIDAY AFTERNOON AND
EVENING...SENDING A WEAK COLD FRONT SOUTH DURING THIS TIME AS WELL.
STILL SOME SUBTLE TIMING DIFFERENCES WITH THE SHORTWAVE AND
FRONT...WHICH ISN/T SURPRISING CONSIDERING THE FAST ZONAL FLOW. WILL
SEE BREEZY TO WINDY WEST WINDS SOUTH OF THE FRONT...WITH WINDS
DECREASING AND TURNING TO THE NORTH IN ITS WAKE. FRONTAL TIMING MAKES
FOR A TRICKY TEMPERATURE FORECAST...BUT WILL AIM FOR LOWER 50S
NORTHEAST TO AROUND 70F IN THE FAR SOUTH FOR NOW. LOW-LEVELS APPEAR
WAY TOO DRY FOR THE SHORTWAVE TO SQUEEZE OUT ANY PRECIP.
LEE TROUGHING WILL QUICKLY RE-DEVELOP ON SATURDAY BENEATH A CONTINUED
ZONAL FLOW ALOFT. SOUTH/SOUTHWEST WINDS WILL RETURN IN RESPONSE...AND
UNSEASONABLY WARM CONDITIONS WILL CONTINUE. ANOTHER SHORTWAVE WILL
MOVE ACROSS SATURDAY NIGHT/SUNDAY...SENDING ANOTHER WEAK COLD FRONT
THROUGH. AGAIN...THIS WAVE LOOKS TO BE MOISTURE STARVED AND THE FRONT
WILL HAVE LITTLE EFFECT ON TEMPERATURES. WARM...DRY CONDITIONS TO
PERSIST THROUGH MONDAY AHEAD OF THE NEXT UPPER TROUGH WORKING ACROSS
THE WEST.
THERE REMAINS QUITE A BIT OF UNCERTAINTY REGARDING THE POTENTIAL
SYSTEM FOR EARLY TO MID NEXT WEEK. MODEL SOLUTIONS CONTINUE TO WAVER
BETWEEN A CLOSED LOW AND A PROGRESSIVE OPEN WAVE AFFECTING THE
PANHANDLES CENTERED ON THE TUESDAY TIMEFRAME. LATEST 12Z RUNS OF THE
GFS AND ECMWF ARE BOTH NOW ADVERTISING AN OPEN WAVE AND ONLY MINIMAL
PRECIPITATION CHANCES. WILL MAINTAIN SOME SMALL POPS TUESDAY
ATTM...AND SEE HOW LATER RUNS TREND. DID WARM TEMPS SLIGHTLY ON
TUESDAY AND TRIMMED THE RAIN/SNOW MIX BACK TO THE NORTHWEST. DRY BUT
COOLER CONDITIONS THEN EXPECTED WEDNESDAY BEHIND THE DEPARTING UPPER
TROUGH/LOW.
KB
FIRE WEATHER...
A COLD FRONT WILL BACK INTO THE EASTERN OKLAHOMA PANHANDLE AND
NORTHEAST TEXAS PANHANDLE ON THURSDAY...SETTING UP A SOUTHWEST TO
NORTHEAST TEMPERATURE GRADIENT ACROSS THE AREA. THIS FRONT WILL ALSO
KEEP WINDS LIGHTER...WITH SPEEDS EXPECTED TO REMAIN BELOW 15 MPH.
THUS...ELEVATED FIRE WEATHER CONDITIONS ARE NOT EXPECTED DESPITE
AFTERNOON RELATIVE HUMIDITIES FALLING TO 15 TO 20 PERCENT ACROSS THE
SOUTHWEST HALF OF THE PANHANDLES. UNSEASONABLY WARM TEMPERATURES WILL
CONTINUE INTO FRIDAY. WESTERLY WINDS WILL INCREASE AHEAD OF THE NEXT
COLD FRONT...WHICH IS EXPECTED TO MOVE THROUGH DURING THE AFTERNOON
OR EVENING HOURS. ELEVATED FIRE WEATHER CONDITIONS WILL BE POSSIBLE
ACROSS THE SOUTHWEST HALF OF THE AREA...WITH CRITICAL CONDITIONS
POSSIBLE ACROSS THE SOUTHWEST AND SOUTH CENTRAL TEXAS PANHANDLE WHERE
WESTERLY WINDS WILL INCREASE TO 20 TO 30 MPH WITH HIGHER GUSTS AND
MINIMUM RELATIVE HUMIDITIES WILL FALL TO 15 TO 20 PERCENT. A FIRE
WEATHER WATCH HAS BEEN ISSUED FOR THESE AREAS. THERE IS STILL SOME
UNCERTAINTY REGARDING TIMING OF THE COLD FRONT...AND A FASTER ARRIVAL
COULD POTENTIALLY EASE FIRE WEATHER CONCERNS WHILE A SLOWER ARRIVAL
MAY ALLOW CRITICAL CONDITIONS TO DEVELOP OVER A LARGER AREA.
UNSEASONABLY WARM CONDITIONS WILL CONTINUE OVER THE WEEKEND INTO
MONDAY. COMBINED WITH BREEZY CONDITIONS...ELEVATED FIRE WEATHER
CONDITIONS WILL BE POSSIBLE SATURDAY THROUGH MONDAY ACROSS WESTERN
AND CENTRAL PORTIONS OF THE AREA.
KB
&&
.AMA WATCHES/WARNINGS/ADVISORIES...
TX...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DEAF SMITH...
OLDHAM...POTTER...RANDALL.
OK...NONE.
&&
$$
KS/JJ
AREA FORECAST DISCUSSION
NWS DENVER CO
352 AM MST THU JAN 19 2012
.SHORT TERM...A STRONG NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER
THE CWFA TODAY AND TONIGHT. STRONG WINDS HAVE NOT BEEN AS
WIDESPREAD THIS MORNING AS THE MDLS HAD SUGGESTED. THE STRONGEST
WINDS APPEARED TO HAVE OCCUR PRIOR TO MIDNIGHT. ALTHOUGH THE JET
MAX HAS SHIFTED TO THE NORTH AND EAST...THE SHEAR APPEARS TO HAVE
LESSENED THE IMPACT OF THE MOUNTAIN WAVE SO FAR THIS MORNING. IF
WE GET ANY MORE STRONG WINDS IT WILL LIKELY OCCUR PRIOR TO 15Z
THIS MORNING. IF IT DOES NOT MATERIALIZE BY THAT TIME...THEN THE DAY
SHIFT CAN CANCEL THE HIGH WIND WARNING. THE SAME CAN BE SAID FOR
THE BLIZZARD WARNING. LGT SNOW HAS DEVELOPED IN THE MOUNTAINS
OVERNIGHT AND STRONG WINDS APPEAR TO BE IMPACTING TRAVEL NEAR THE
EISENHOWER TUNNEL. THE BLIZZARD CONDITIONS WILL BE MORE WIDESPREAD
ABOVE TIMBERLINE. THOSE WINDS ARE STILL EXPECTED TO DECREASE IN
MAGNITUDE BY THIS AFTERNOON. ADDITIONAL HIGHLIGHTS MAY BE
NECESSARY FOR ZONE 33 AND 34 THIS AFTN AND TNGT. WILL LET THE
CURRENT HIGHLIGHT RUN ITS COURSE. NOT SURE THE SNOW WILL BE ENUF
TO WARRANT A WINTER STORM WARNING VS A WINTER WEATHER ADVISORY
FOR SNOW AND BLOWING SNOW. THE MDLS APPEAR TO HIT THE MOUNTAINS
NORTH OF INTERSTATE 70 THE HARDEST. THE WINTER STORM WARNING FOR
ZONE 31 STILL LOOKS ON TRACK AND ZONE 33 WILL GET SOME DECENT
SNOWFALL AS WELL. THE BEST POTENTIAL FOR SNOW WILL BE TONIGHT AS
THE MOISTURE WEST OF THE CONTINENTAL DIVIDE DEEPENS AND THE MID
LEVEL LAPSE RATES IMPROVE. NAM12 SPATIAL CROSS-SECTIONS KEEP AN
80 KTS CROSS- MOUNTAIN COMPONENT OF 80 KTS AROUND 600 MB LATE THIS
AFTN AND TONIGHT. THE WAVE AMPLICATION OVERNIGHT APPEARS FAIRLY
LIMITED SO DO NOT ANTICIPATE HIGH WINDS IN THE FOOTHILLS AS MUCH
TONIGHT. AS FOR THE NORTHEAST PLAINS...IT WILL BE DRY WITH
TEMPERATURES IN THE MID 50S TO LOWER 60S... MILDEST NEAR THE
FOOTHILLS. OVERALL ONLY MINOR ADJUSTMENTS IN THE SHORT TERM.
.LONG TERM...STRONG WESTERLY FLOW ALOFT WILL CONTINUE TO TRANSPORT
PACIFIC MOISTURE ACROSS THE WESTERN U.S. THROUGH THE WEEKEND. THE
NEXT WRINKLE IN THE FLOW ALOFT WILL MOVE ACROSS THE STATE TONIGHT
AND FRIDAY. THE MOISTURE EMBEDDED IN THE STRONG WESTERLY FLOW ALOFT
WILL PRODUCE A ROUND OF OROGRAPHIC SNOW. LAPSE RATES WILL BE AROUND
5-6 C/KM...NOT THAT GREAT BUT NOT BAD EITHER. BEST SNOW ON FRIDAY
WILL OCCUR OVER WESTERN JACKSON COUNTY WHERE LOCALLY A FOOT OF NEW
SNOW IS POSSIBLE. LESSER AMOUNTS ARE EXPECTED TO THE SOUTH OVER THE
MOUNTAINS OF GRAND AND JACKSON COUNTIES. THIS SYSTEM IS PRIMARILY AN
OROGRAPHIC SNOW PRODUCER. THE MOUNTAIN VALLEYS WILL SEE A FEW STRAY
SNOW SHOWERS OFF THE MOUNTAINS. FOR THE FRONT RANGE AND EASTERN
PLAINS...DRY AND MILD CONDITIONS WILL PREVAIL.
WILL SEE A BREAK IN THE SNOW FRIDAY NIGHT AND SATURDAY. SLIGHT
RIDGING WILL OCCUR DUE TO THE NEXT SHORT WAVE TROUGH NEARING THE
ROCKIES. THIS NEXT SYSTEM WILL MOVE ACROSS THE STATE SATURDAY
NIGHT...WITH SNOW STARTING OVER NORTH CENTRAL COLORADO LATE SATURDAY
AFTERNOON. THIS WAVE IS STRONGER THAN THURSDAY NIGHT/FRIDAY`S
SYSTEM. IN ADDITION...LAPSE RATES WILL BE 7-8 C/KM SATURDAY NIGHT.
ALL OF THIS WILL PRODUCE A PERIOD OF MODERATE TO HEAVY OROGRAPHIC
SATURDAY NIGHT. WILL LIKELY NEED WINTER WEATHER HIGHLIGHTS AS THIS
SYSTEM NEARS. WOULD EXPECT THE FAVORED OROGRAPHIC SLOPES TO PICK UP
1-2 FEET OF SNOW. MOST OF THE SNOW WILL AGAIN BE OROGRAPHICALLY
DRIVEN. THERE WILL BE A BETTER CHANCE FOR SNOW IN THE MOUNTAINS
VALLEYS DUE TO BETTER INSTABILITY. WILL NOT RULE OUT THE CHANCE OF A
FEW LIGHT SNOW SHOWERS OVER THE PLAINS EITHER. ANY PRECIPITATION
HERE WILL BE LIGHT. AFTER A MILD SATURDAY OVER NORTHEAST COLORADO
WHERE HIGHS WILL BE IN THE 50S...COOLER AIR WILL MOVE IN BEHIND THE
SYSTEM FOR SUNDAY WITH HIGHS IN THE 40S.
PROGRESSIVE WEATHER PATTER WILL CONTINUE THROUGH THE EARLY PART OF
NEXT WEEK. RIDGING ON MONDAY WILL BE FOLLOWED BY A TROUGH ON
TUESDAY. THEN ANOTHER RIDGE TO AFFECT THE AREA LATE WEDNESDAY AND
INTO THURSDAY. WILL KEEP POPS IN THE MOUNTAINS EACH DAY DUE TO THE
SOMEWHAT MOIST WESTERLY FLOW AND ALSO DUE TO TIMING UNCERTAINTIES
WITH THESE SYSTEMS. THE ENERGY WITH THE SYSTEM ON TUESDAY LOOKS LIKE
IT WILL SPLIT AND MOVE AROUND COLORADO. THIS WILL KEEP MOUNTAIN
SNOWFALL AMOUNTS ON THE LIGHTER SIDE. FOR THE PLAINS...OTHER THAN
LOW POPS FOR THE SYSTEM MONDAY NIGHT TUESDAY WILL KEEP THE FORECAST
DRY. HIGHS WILL BE NEAR NORMAL AFTER THE TROUGH PASSAGE
TUESDAY...OTHERWISE ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR
NORTHEAST COLORADO.
&&
.AVIATION...WIND WILL CONTINUE TO BE AN ISSUE...ESPECIALLY AT KBJC
AND KDEN THIS MORNING. AT KDEN WILL CONTINUE WITH A WESTERLY WIND
THIS MORNING UNTIL AROUND 15Z THEN IT APPEAR TO WEAKEN AND BECOME
MORE SWLY. NONE OF THE MDLS HAVE HANDLED THE WIND PATTERN VERY
WELL THIS MORNING. I WILL BE FOLLOWING THE RUC BOUNDARY LAYER
WINDS THIS MORNING. IF THE SFC TROUGH SITS ALONG THE FRONT RANGE
THIS AFTN...THEN SOME SORT OF ELY WIND COMPONENT IS STILL
POSSIBLE. AS FOR KBJC...WINDS HAVE BEEN SLOW TO MATERIALIZE THIS
MORNING. WILL KEEP THE STRONGER GUSTS IN THE TAF UNTIL 15Z THEN
DECREASE IT THEREAFTER.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL NOON MST TODAY FOR COZ035-036-038-039.
BLIZZARD WARNING UNTIL NOON MST TODAY FOR COZ033-034.
WINTER STORM WARNING UNTIL 5 PM MST FRIDAY FOR COZ031.
&&
$$
SHORT TERM...COOPER
LONG TERM....MEIER
AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
921 AM EST THU JAN 19 2012
.SYNOPSIS...
AN AREA OF HIGH PRESSURE OVER THE LOWER HUDSON VALLEY IN NEW YORK
STATE WILL MOVE OFF TO THE EAST THROUGH TONIGHT. LOW PRESSURE WILL MOVE
ACROSS ONTARIO AND QUEBEC TODAY AND TONIGHT. IT WILL CAUSE A COLD
FRONT TO MOVE ACROSS OUR REGION. MORE HIGH PRESSURE WILL SETTLE
ACROSS THE AREA FRIDAY AND THEN WITHDRAW EASTWARD FRIDAY NIGHT.
ANOTHER LOW PRESSURE SYSTEM WILL BRING MORE UNSETTLED WEATHER TO
THE AREA SATURDAY. MORE HIGH PRESSURE WILL FOLLOW FOR SUNDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
THE ESTF UPDATE WAS BASICALLY SOME SMALL POP TWEAKING. TEMPS, DEWS
AND WINDS ARE LOOKING GOOD. THE HRRR WAS VERIFYING THE BEST OF
THE MODELS (RGEM SECOND) AS TO WHERE THE SNOW WAS REACHING THE
GROUND IN THE GREAT LAKES. BASED ON THOSE MODELS AND A QUICK
GLANCE AT THE NEW SREF, WE SLOWED THE ARRIVAL OF THE SNOW SLIGHTLY
FAR NORTHWEST.
AHEAD OF THE SHORT WAVE...SURFACE HIGH PRESSURE WILL CREST OVER THE
REGION THIS MORNING...THEN MOVE OFFSHORE THIS AFTERNOON. 0000 UTC
SOUNDINGS ACROSS THE AREA WHERE BONE DRY (WITH PRECIPITABLE WATER
VALUES NEAR 0.10 INCHES). THE ENTIRE COLUMN IS DRY...AND THE WARM
AIR ADVECTION AHEAD OF THE IMPRESSIVE SHORT WAVE WILL GO INTO
MOISTENING THE COLUMN. THIS WILL MANIFEST ITSELF AS INCREASING HIGH
AND THEN MID LEVEL CLOUDINESS.
THE COLUMN COULD MOISTEN IN THE BETTER WARM AIR ADVECTION ENOUGH
ACROSS THE LEHIGH VALLEY AND THE SOUTHERN POCONOS FOR SOME FLURRIES
LATE...BUT BASED ON HOW DRY THE AIRMASS IS NOW...EVEN THESE
LOCATIONS SHOULD STAY DRY THROUGH DUSK. MODEL SOUNDINGS SUGGEST THAT
MOS VALUES ARE CLOSE FOR HIGHS...AND A BLEND WAS USED FOR TODAY.
AS THE SURFACE HIGH GETS FARTHER EAST THIS MORNING...THE RETURN
FLOW INCREASES THIS AFTERNOON. MODEL SOUNDINGS SHOW THE DEPTH OF
THE MIXED LAYER WILL BE ENOUGH FOR SOUTHERLY WINDS TO GUST TO 20
MPH THIS AFTERNOON...MAINLY NEAR THE COAST AND IN THE HIGHER
TERRAIN.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
THE MAIN FORECAST PROBLEM FOR TONIGHT INCLUDE PRECIPITATION
COVERAGE...SNOW AMOUNTS...AND WHETHER THE LOW LEVEL JET WILL PRODUCE
WIND GUSTS NEAR THE COAST AFTER MIDNIGHT.
THE APPROACHING SHORT WAVE WILL TRY TO INDUCE A LAYER OF MID LEVEL
FRONTOGENETIC FORCING ACROSS CENTRAL AREAS THIS EVENING. THE AIRMASS
WILL STILL BE FAIRLY DRY...AS THE WAA INDUCED LIFT NOW AHEAD OF THE
SHORT WAVE IS MOSTLY DRY. THE FRONTOGENETIC FORCING APPEARS TO BE
MAXIMIZE DURING THE EVENING HOURS ACROSS CENTRAL AND NORTHERN
AREAS. IT WOULD APPEAR AS THOUGH THE SOUTH TO SOUTHWEST CROSS
BARRIER FLOW ACROSS THE HIGHER TERRAIN WILL HELP SQUEEZE OUT THE
AVAILABLE MOISTURE. THE COMBINATION OF LIFT AND SQUEEZING DUE TO
OROGRAPHIC EFFECTS SHOULD ALLOW NORTHERN AREAS SEE LIGHT SNOW
DEVELOP THIS EVENING.
QPF AMOUNTS FOR THIS EVENT ARE RATHER MEAGER...BASED ON WHAT IS
OCCURRING UPSTREAM AND THE GENERAL DRYNESS OF THE AIRMASS IN PLACE.
RIGHT NOW...IT LOOKS LIKE THE HIGHER TERRAIN OF THE SOUTHERN POCONOS
AND NORTHWEST NEW JERSEY. THE BEST DYNAMIC LIFT ASSOCIATED WITH THE
SHORT WAVE SHOULD PASS NORTH OF THE AREA...AND BASED ON THE QPF WE
COULD SEE AN INCH OR TWO IN THE HIGHER TERRAIN.
FURTHER SOUTH...THE SOUTHERN EXTENT OF THE PRECIPITATION BECOMES A
BIT MORE NEBULOUS. THE WARM AIR ADVECTION WILL MOISTEN THE
COLUMN...BUT ONLY TO A POINT. IT WOULD APPEAR THAT AREAS SOUTH OF AN
KMQS-KPHL-KACY LINE MAY BE JUST TOO DRY FOR THE WARM AIR ADVECTION
TO BE OF MUCH HELP. IN BETWEEN THE HIGHER TERRAIN AND THE
ABOVEMENTIONED LINE...PRECIPITATION CHANCES WERE GRADUATED FROM
NORTH TO SOUTH.
THE WARM AIR ADVECTION MAY ALSO PLAY HAVOC WITH LIGHT PRECIPITATION
TYPE. IN PLACES WHERE PRECIPITATION IS STEADY...THE EVAPORATIVE
COOLING SHOULD ALLOW A NEAR ISOTHERMAL PROFILE...AND THE SNOW SHOULD
BE THE MAIN PRECIPITATION TYPE. FOR THE LOWER LEHIGH VALLEY THROUGH
THE DELAWARE VALLEY INTO CENTRAL NEW JERSEY...THE PRECIPITATION TYPE
COULD BE DOMINATED BY PRECIPITATION RATES...AND THE FURTHER SOUTH
ONE GOES INTO THE AIRMASS IN PLACES...A MIX OF RAIN COULD BE MORE
THE DOMINANT TYPE DUE TO CONTINUED WARM AIR ADVECTION.
SINCE TEMPERATURES HAVE BEEN COLD THE PAST DAY OR SO...COLDER
SURFACES MAY BE ABLE TO SUPPORT LIGHT SNOW ACCUMULATIONS OUTSIDE OF
THE TERRAIN. FOR NOW...HOWEVER...SNOWFALL AMOUNTS APPEAR TO BE LESS
THAN AN INCH.
THE MAIN THRUST OF WARM AIR ADVECTION INDUCED PRECIPITATION SHOULD
EXIT THE AREA AHEAD OF THE COLD FRONT ASSOCIATED WITH THE STRONG
SHORT WAVE. AHEAD OF THE FRONT IN THE WARM AIR ADVECTION...MODEL
SOUNDINGS ARE SUGGESTING THAT DELAWARE AND COASTAL NEW JERSEY COULD
SEE MIXING LAYERS DEEP ENOUGH TO SUPPORT WIND GUSTS TO 35 MPH AS A
LOW LEVEL JET CROSSES AREAS LATE THIS EVENING AND OVERNIGHT. AS IS
USUALLY THE CASE WITH WARM AIR ADVECTION AND LOWERING INVERSIONS...
THE GUSTINESS OF THE WINDS APPEAR TO BE PROBLEMATIC. FOR NOW WIND
GUSTS WILL BE KEPT BELOW 35 MPH ALONG THE COAST...AND IN ANY EVENT
DO NOT APPEAR TO SUPPORT WIND ADVISORY CRITERIA.
TEMPERATURES PROBABLY DROP A BIT THIS EVENING...THEN REMAIN MORE OR
LESS STEADY THROUGH THE COLD FRONTAL PASSAGE. SINCE MOS SEEMS TO BE
PICKING UP ON THIS...A BLEND OF MOS NUMBERS WAS USED FOR LOWS.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
FAIR WEATHER IS EXPECTED FRI AS HIGH PRESSURE BUILDS BACK ACROSS
THE AREA. A FEW LINGERING NOW SHOWERS MAY CONTINUE EARLY IN THE
DAY ACROSS THE SOUTHERN POCONOS.
THE NEXT SYSTEM WILL BRING MORE CLOUDS AND PRECIPITATION TO THE
AREA SATURDAY INTO SATURDAY NIGHT. IT APPEARS THAT THE NORTHERN
AREAS WILL BE COLD ENOUGH FOR (MOSTLY) SNOW AND MAYBE SOME SLEET
WITH THE LOW. SOME ACCUMULATIONS WILL OCCUR...MAYBE SEVERAL
INCHES...AND WWA FLAGS MAY BE NEEDED IN UPCOMING FCSTS. THE LOW
WILL BRING SOME SNOW TO CENTRAL AREAS OF NJ AND METRO
PHILADELPHIA TOO...BUT TEMPERATURES MAY WARM ENOUGH TO CAUSE A
CHANGE OVER TO RAIN DURING THE DAY...REDUCING THE ACCUMULATIONS.
MOSTLY RAIN IS EXPECTED ACROSS THE DELMARVA. THE SYSTEM MOVES TO
THE EAST SAT NIGHT AND PRECIPITATION SHOULD END BY SUN MORNING.
FAIR WEATHER IS EXPECTED SUN AS HIGH PRESSURE WEDGES DOWN FROM
CANADA. ANOTHER LOW WILL DEEPEN ACROSS THE PLAINS AND SEND MORE
WARM AIR AND RAIN TO THE AREA MON-TUE. THE LATEST EC IS SLOWER
WITH THIS SYSTEM AS COMPARED TO THE GFS...SO WITH THE MODEL
DIFFERENCES...FEW CHANGES WERE MADE IN THE TUE OR WED PERIODS OF
THE FCST.
&&
.AVIATION /14Z THURSDAY THROUGH MONDAY/...
SURFACE HIGH PRESSURE IS ABOUT TO CREST OVER THE REGION... WHICH
IS KEEPING A BIT OF A NORTH TO NORTHEAST GRADIENT AHEAD OF THE
HIGH...AND THIS IS IN TURN KEEPING WINDS FROM BECOMING LIGHT AND
VARIABLE. THIS WILL LIKELY HAPPEN BEFORE SUNRISE.
VFR CONDITIONS ARE EXPECTED TODAY...AS HIGH AND MID LEVEL CLOUDINESS
INCREASE AND THICKEN. THE LIGHT NORTH TO NORTHEAST GRADIENT EARLY
THIS MORNING WILL DIMINISH...AND AS THE SURFACE HIGH GETS
OFFSHORE...THE RETURN FLOW INCREASES THIS AFTERNOON. MODEL SOUNDINGS
SUGGEST THAT WIND GUSTS TO ABOUT 18 KNOTS ARE POSSIBLE THIS
AFTERNOON...AND THE WIND DIRECTION LOOKS TO BE 180-190 DEGREES. THIS
MAY HAVE SOME OPERATIONAL IMPACT AT KPHL THIS AFTERNOON...BUT THE
GUSTS ARE EXPECTED TO DIMINISH BY 2300 UTC.
A COLD FRONT APPROACHING THE REGION THIS AFTERNOON AND EVENING WILL
ALLOW LOWER CLOUDS TO DEVELOP AHEAD OF IT. THE COLD FRONT HAS A BAND
OF SNOW WITH AND JUST AHEAD OF IT ACROSS THE WESTERN GREAT LAKES
EARLY THIS MORNING. IT APPEARS AS THOUGH THE FORCING FOR THE SNOW
WILL PASS MAINLY NORTH OF THE AREA TONIGHT...BUT COULD CLIP KABE AND
PERHAPS KRDG WITH LIGHT SNOW. THE 0600 UTC INCLUDES MVFR CONDITIONS
FOR LIGHT SNOW AT KABE AND HINTS AT THE POTENTIAL FOR KRDG.
FURTHER SOUTH...IT IS NOT CLEAR JUST HOW MUCH OF AN IMPACT
PRECIPITATION WILL HAVE. THE AIRMASS WILL WARMER AT THE KPHL METRO
AIRPORTS...SO THE PRECIPITATION COULD FALL AS RAIN OR SNOW. VFR
CONDITIONS WITH THE POSSIBILITY OF LIGHT RAIN AND SNOW IS INDICATED
AT KTTN AND KPNE...BUT NO FURTHER SOUTH AND EAST.
THE FINAL FORECAST ISSUE FOR TONIGHT IS THE POTENTIAL FOR LOW LEVEL
WIND SHEAR. SHORT TERM MODELS SHOW A 40 TO 45 KNOT LOW LEVEL JET
IMPACT THE REGION BETWEEN 0300 AND 0900 UTC FRIDAY. THE INVERSION WILL
LOWER TONIGHT AHEAD OF THE LOW LEVEL JET...AND FOR NOW THE LLWS
REMARK WAS OMITTED FROM THE TERMINAL FORECASTS. THIS WILL BE
REVISITED FOR THE 1200 UTC FORECASTS/
IMPROVED CONDITIONS WILL ARRIVE BEHIND THE DEPARTING SYSTEM ON
FRIDAY WITH VFR EXPECTED FRI MORNING. THIS WILL CARRY INTO THE
EVENING BEFORE THE NEXT SYSTEM APPROACHES FOR SAT MORNING. MORE
WIDESPREAD POOR FLYING WEATHER IS ANTICIPATED FOR SAT AND SAT
NIGHT.
&&
.MARINE...
A SMALL CRAFT ADVISORY WILL BE RAISED WITH THE NEW FORECAST FOR ALL
MARINE ZONES FOR TONIGHT.
THE SURFACE GRADIENT AHEAD OF THE HIGH APPROACHING FROM THE WEST HAS
KEPT THE WINDS BETWEEN 15 AND 20 KNOTS THROUGH THE EARLY MORNING
HOURS. SURFACE STREAMLINES TO THE WEST SUGGEST THIS WILL CHANGE
SOON...AS WINDS DROP OFF...AND VEER TO THE NORTHEAST. AS THE HIGH
GETS OFFSHORE LATER THIS MORNING...THE FLOW WILL VEER TO THE SOUTH
SOUTHWEST.
THE GRADIENT LOOKS AS THOUGH IT CAN SUPPORT GUSTS TO NEAR
20 KNOTS LATE THIS AFTERNOON OVER THE SOUTHERN OCEAN WATERS AND
ACROSS DELAWARE BAY. HOWEVER...MODEL SOUNDINGS MAY BE A BIT TOO
GENEROUS WITH MIXING IN AN INCREASING WARM AIR ADVECTION PATTERN...
AND WINDS AND SEAS WILL BE KEPT BELOW SMALL CRAFT LEVELS THROUGH
DUSK.
AS A COLD FRONT APPROACHES THIS EVENING...THE SURFACE GRADIENT LOOKS
TO BE ABLE TO SUPPORT SMALL CRAFT WINDS ACROSS ALL WATERS...PROBABLY
STARTING IN THE NEIGHBORHOOD OF 0000 UTC. MODELS HAVE BEEN
CONSISTENT SHOWING A LOW LEVEL JET CROSSING THE REGION LATE THIS
EVENING AND DURING THE OVERNIGHT. MODEL SOUNDINGS SHOW A 3 HOUR
WINDOW (CENTERED AROUND 0600 UTC FRIDAY) WHERE 30 TO 35 KNOTS OF
WIND DROP BELOW THE INVERSION.
TYPICALLY...IT IS DIFFICULT TO GET A SOUTHWEST FLOW IN STRONG WARM
AIR ADVECTION TO WORK ITS WAY BELOW A LOWERING INVERSION...AND THIS
LOOKS LIKE A TYPICAL WARM AIR ADVECTION PATTERN. WHILE THE SIGNATURE
IS PRESENT IN BOTH THE NAM AND GFS AT 44009...WILL HOLD OFF ON
ISSUING A GALE WARNING. HOWEVER...30 KNOT GUSTS WILL BE INCLUDED IN
THE FORECAST FOR THE SOUTHERN OCEAN WATERS AND THE LOWER DELAWARE
BAY...WHERE THE LOW LEVEL JET WILL MAKE ITS CLOSEST PASS. IF ANY
PLACES END UP NEEDING A SHORT FUSED GALE WARNING TONIGHT...IT WOULD BE
THE ABOVEMENTIONED LOCATIONS.
THE COLD FRONT IS EXPECTED TO CROSS THE COASTAL WATERS BETWEEN 0800
AND 1200 UTC FRIDAY. THE COLD AIR ADVECTION BEHIND THE COLD FRONT
DOES NOT APPEAR TO BE SUFFICIENT TO KEEP WINDS AT SMALL CRAFT
LEVELS. THEREFORE...THE SMALL CRAFT ADVISORY WILL COVER JUST THE
TONIGHT PERIOD.
MORE SMALL CRAFT ADVISORY CONDITIONS WILL DEVELOP ON THE WATERS
WITH THE SYSTEM THAT WILL AFFECT THE WATERS SATURDAY NIGHT AND
SUNDAY. THE ENHANCED SEAS MAY PERSIST INTO MONDAY.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST FRIDAY
FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...O`HARA
NEAR TERM...GIGI/HAYES
SHORT TERM...HAYES
LONG TERM...O`HARA
AVIATION...HAYES/O`HARA
MARINE...HAYES/O`HARA
AREA FORECAST DISCUSSION
NWS MIAMI FL
924 AM EST THU JAN 19 2012
.UPDATE...
A WEAK BOUNDARY WAS MOVING THROUGH SOUTH FLORIDA THIS MORNING. THE
ONLY NOTABLE FEATURE IS THE CLOUD COVER ACROSS DEEP SOUTH FLORIDA.
THIS BOUNDARY WILL BECOME EVEN MORE DIFFUSE LATER TODAY...BUT DRIER
AIR WILL CONTINUE TO FILTER INTO THE REGION. SLIGHTLY COOLER
TEMPERATURES ARE EXPECTED THIS AFTERNOON. NO MAJOR UPDATES NEEDED
THIS MORNING.
&&
.PREV DISCUSSION... /ISSUED 546 AM EST THU JAN 19 2012/
AVIATION...WEAKENING COLD FRNT APRCHG LK OKEE AREA AND WL MOV
INTO S FLA AND MOV OFF OF THE SE COAST ARND 15Z. MVFR CIGS WITH
LCL IFR OCCURRING AHD OF FRNT. MVFR CIGS PSBL E COAST TERMINALS
11Z-14Z THEN VFR ALL TERMINALS THRU THE END OF THE PD. SFC WNDS
NNW-N < 10 KTS BCMG NNE ALL TERMINALS AFT 18Z AND INCRG 10 TO 15
KTS THEN DCRG < 10 KTS AFT 00Z. POTENTIAL EXISTS THAT AN OFSHR
WND FLOW MAY DVLP LATE TONIGHT BUT NOT IN TAFS ATTM.
PREV DISCUSSION... /ISSUED 324 AM EST THU JAN 19 2012/
DISCUSSION...
LATEST DEW POINT SURFACE ANALYSIS REVEALS LEADING EDGE OF WEAK
FRONTAL BOUNDARY CURRENTLY ACROSS SOUTH CENTRAL FLORIDA BETWEEN
ORLANDO AND LAKE OKEECHOBEE. ANALYSIS OF MODEL GUIDANCE TRACKING THIS
FEATURE INDICATES THE BOUNDARY WILL BE ACROSS SOUTH FLORIDA BY
LATE MORNING AND/OR EARLY AFTERNOON. GLOBAL MODELS IN FACT BRING
IT THROUGH THE AREA BUT THE HIRES MODELS INCLUDING NCEP HIRES NMM
AND ARW AS WELL AS THE LOCAL WRF AND THE RUC INDICATE THE BOUNDARY
WILL SIMPLY DISSIPATE ACROSS THE AREA AS IT MOVES INTO SOUTH
FLORIDA TODAY. EITHER WAY DRIER AIR WILL BE MOVING INTO THE AREA
WITH IT. AHEAD OF IT, RADAR AND SATELLITE INDICATED SOME
CONVECTION EARLIER THIS MORNING MOVING INTO THE GULF WATERS BUT
IT HAS DISSIPATED SINCE THEN AS LOW LEVEL FORCING WITH THE FRONT
WEAKENS AND AS IT MOVES FARTHER AWAY FROM UPPER LEVEL DYNAMICS
WELL REMOVED TO THE NORTH. SO FAR LOOKS LIKE CLOUDS ASSOCIATED
WITH THE APPROACHING BOUNDARY ARE PREVENTING PATCHY FOG FROM
DEVELOPING THIS MORNING ACROSS INTERIOR AREAS OF SOUTH FLORIDA AND
THAT IS LIKELY TO REMAIN LIKE THAT BUT WILL CONTINUE TO MONITOR
JUST IN CASE. FOR THE MOMENT GIVEN TRENDS LEFT THAT OUT OF THE
FORECAST FOR THIS MORNING.
AHEAD OF THE BOUNDARY TODAY THERE WILL BE ONLY A SLIGHT CHANCE OF A
SHOWER, BEST OVER THE COASTAL WATERS, WITH DRIER AIR MASS
GRADUALLY MOVING IN PARTICULARLY BEGINNING AROUND MID TO LATE
MORNING AND INTO THE EARLY AFTERNOON. YET RAIN CHANCES NOT ENOUGH
TO MENTION IN THE FORECAST. AS ALLUDED TO ABOVE, THE BOUNDARY IS
EXPECTED TO STALL AND DISSIPATE BETWEEN MAINLAND SOUTH FLORIDA AND
THE STRAITS THROUGH TONIGHT. TEMPERATURES WILL CONTINUE TO BE WARM
WITH HIGHS IN THE 70S TODAY...AND THEN INTO THE UPPER 70S TO THE
LOWER 80S BY FRIDAY AND INTO THE WEEKEND. WITH THE DRIER AIR AND
EXCELLENT RADIATIONAL COOLING...OVERNIGHT LOWS TONIGHT MAY GET
INTO THE MID 40S ACROSS THE NORTHWEST INTERIOR. ALSO WITH LIGHT
WINDS AND LOW LEVEL FLOW TURNING FROM THE NORTHEAST, IT IS
POSSIBLE THAT PATCHY FOG DEVELOPS INLAND AROUND LAKE OKEECHOBEE
TONIGHT AND AGAIN FRIDAY NIGHT. HOWEVER, CHANCES OF THAT ARE BEST
FRIDAY NIGHT AS BY THEN RETURN FLOW FROM THE ATLANTIC WOULD HAVE
HAD MORE TIME TO MOISTEN UP THE LOW LEVELS A BIT. BUT GIVEN ALL
MOS GUIDANCE DEVELOP IT TONIGHT ALSO, I PUT IT IN THE GRIDS.
OVERALL TONIGHT WILL BE THE COOLEST NIGHT OF THE COMING WEEK. A
CAVEAT HERE IS THAT THE MET GUIDANCE IS SIGNIFICANTLY WARMER THAN
THE MAV FOR NORTHEAST PORTIONS OF THE AREA (PALM BEACH COUNTY). NAM
IS BANKING ON LOT OF CLOUDS RETURNING QUICKLY WITH LOW LEVEL FLOW
SHIFTING FROM THE NE. BUT AT THIS TIME DECIDED TO STICK WITH MAV.
FLOW WILL NOT BE THAT STRONG AND A LAND BREEZE COULD PREVENT THIS
SCENARIO FROM HAPPENING TOO. EKDMOS ENSEMBLE GUIDANCE ALSO SHOWS A
MEAN IN THE MID TO UPPER 50S.
SO WITH THAT SAID, TEMPS TONIGHT WILL STILL BE A COUPLE OF DEGREES
ABOVE NORMAL ACROSS SOUTH FLORIDA WITH A WARMING TREND IN STORE FOR
THE UPCOMING WEEKEND AND INTO THE FIRST PART OF NEXT WEEK WHEN
MODELS GENERALLY AGREE ON HIGH PRESSURE ALOFT BUILDING FROM THE
SOUTHERN GULF OF MEXICO ACROSS CUBA AND INTO THE BAHAMAS, KEEPING
JET STREAM AND STORM TRACKS WELL TO OUR NORTH. GFS IS THE MOST
AGGRESSIVE OF THE MODELS BUILDING THE AFOREMENTIONED HIGH ALOFT BUT
THE MEAN OF THE ENSEMBLE IS STILL CONSISTENT WITH THE SCENARIO AND
SO IS THE ECMWF. BOTTOM LINE, THE ENSUING WARMING TREND WILL RESULT
IN OVERNIGHT LOWS RUNNING CLOSE TO 10 DEGREES ABOVE NORMAL BY LATE
IN THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK ALONG WITH
DAYTIME HIGHS RUNNING AROUND 5 DEGREES ABOVE NORMAL.
IT WILL REMAIN DRY FOR THE MOST PART THROUGH THE WEEKEND WITH A
SLIGHT CHANCE OF SHOWERS MAY BE COMING BACK INTO THE PICTURE BY THE
EARLY TO MIDDLE PART OF NEXT WEEK AS LOW LEVEL MOISTURE SLOWLY
RETURNS FROM THE SOUTH BUT NOT LOOKING TOO PROMISING AT THIS TIME.
MARINE...
A BRIEF SURGE IN WIND OF UP TO 15 TO 20 KNOTS TODAY OFF THE COAST
OF PALM BEACH FROM THE NORTH NORTHEAST WILL RESULT IN A SHORT
LIVED SURGE IN SEAS OF UP TO 6 FEET IN THE GULF STREAM. SO WILL
PUT UP A SMALL CRAFT SHOULD EXERCISE CAUTION FOR THOSE WATERS
TODAY. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW 10 TO 15 KNOTS
AND BELOW 4 FEET INTO THE EARLY PART OF NEXT WEEK.
FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES TODAY WILL BE BELOW 35 PERCENT IN
AREAS NORTH OF ALLIGATOR ALLEY ACROSS NORTHERN COLLIER, HENDRY,
AND GLADES COUNTIES TODAY FOR CLOSE TO 4 HOURS. HOWEVER ERC VALUES
ACROSS THE AREA REMAIN TOO LOW FOR ANY RED FLAG CONCERNS. AFTER
TODAY, LOW LEVEL MOISTURE WILL BE ON THE INCREASE AND SO NO OTHER
FIRE CONCERNS AT THIS TIME INTO EARLY NEXT WEEK AT THE VERY LEAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 55 76 61 / - - - -
FORT LAUDERDALE 75 61 77 66 / - - - -
MIAMI 76 60 77 65 / - - - -
NAPLES 73 52 78 57 / - - - -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...47/RGH
AREA FORECAST DISCUSSION
NWS MIAMI FL
546 AM EST THU JAN 19 2012
.AVIATION...WEAKENING COLD FRNT APRCHG LK OKEE AREA AND WL MOV
INTO S FLA AND MOV OFF OF THE SE COAST ARND 15Z. MVFR CIGS WITH
LCL IFR OCCURRING AHD OF FRNT. MVFR CIGS PSBL E COAST TERMINALS
11Z-14Z THEN VFR ALL TERMINALS THRU THE END OF THE PD. SFC WNDS
NNW-N < 10 KTS BCMG NNE ALL TERMINALS AFT 18Z AND INCRG 10 TO 15
KTS THEN DCRG < 10 KTS AFT 00Z. POTENTIAL EXISTS THAT AN OFSHR
WND FLOW MAY DVLP LATE TONIGHT BUT NOT IN TAFS ATTM.
&&
.PREV DISCUSSION... /ISSUED 324 AM EST THU JAN 19 2012/
DISCUSSION...
LATEST DEW POINT SURFACE ANALYSIS REVEALS LEADING EDGE OF WEAK
FRONTAL BOUNDARY CURRENTLY ACROSS SOUTH CENTRAL FLORIDA BETWEEN
ORLANDO AND LAKE OKEECHOBEE. ANALYSIS OF MODEL GUIDANCE TRACKING THIS
FEATURE INDICATES THE BOUNDARY WILL BE ACROSS SOUTH FLORIDA BY
LATE MORNING AND/OR EARLY AFTERNOON. GLOBAL MODELS IN FACT BRING
IT THROUGH THE AREA BUT THE HIRES MODELS INCLUDING NCEP HIRES NMM
AND ARW AS WELL AS THE LOCAL WRF AND THE RUC INDICATE THE BOUNDARY
WILL SIMPLY DISSIPATE ACROSS THE AREA AS IT MOVES INTO SOUTH
FLORIDA TODAY. EITHER WAY DRIER AIR WILL BE MOVING INTO THE AREA
WITH IT. AHEAD OF IT, RADAR AND SATELLITE INDICATED SOME
CONVECTION EARLIER THIS MORNING MOVING INTO THE GULF WATERS BUT
IT HAS DISSIPATED SINCE THEN AS LOW LEVEL FORCING WITH THE FRONT
WEAKENS AND AS IT MOVES FARTHER AWAY FROM UPPER LEVEL DYNAMICS
WELL REMOVED TO THE NORTH. SO FAR LOOKS LIKE CLOUDS ASSOCIATED
WITH THE APPROACHING BOUNDARY ARE PREVENTING PATCHY FOG FROM
DEVELOPING THIS MORNING ACROSS INTERIOR AREAS OF SOUTH FLORIDA AND
THAT IS LIKELY TO REMAIN LIKE THAT BUT WILL CONTINUE TO MONITOR
JUST IN CASE. FOR THE MOMENT GIVEN TRENDS LEFT THAT OUT OF THE
FORECAST FOR THIS MORNING.
AHEAD OF THE BOUNDARY TODAY THERE WILL BE ONLY A SLIGHT CHANCE OF A
SHOWER, BEST OVER THE COASTAL WATERS, WITH DRIER AIR MASS
GRADUALLY MOVING IN PARTICULARLY BEGINNING AROUND MID TO LATE
MORNING AND INTO THE EARLY AFTERNOON. YET RAIN CHANCES NOT ENOUGH
TO MENTION IN THE FORECAST. AS ALLUDED TO ABOVE, THE BOUNDARY IS
EXPECTED TO STALL AND DISSIPATE BETWEEN MAINLAND SOUTH FLORIDA AND
THE STRAITS THROUGH TONIGHT. TEMPERATURES WILL CONTINUE TO BE WARM
WITH HIGHS IN THE 70S TODAY...AND THEN INTO THE UPPER 70S TO THE
LOWER 80S BY FRIDAY AND INTO THE WEEKEND. WITH THE DRIER AIR AND
EXCELLENT RADIATIONAL COOLING...OVERNIGHT LOWS TONIGHT MAY GET
INTO THE MID 40S ACROSS THE NORTHWEST INTERIOR. ALSO WITH LIGHT
WINDS AND LOW LEVEL FLOW TURNING FROM THE NORTHEAST, IT IS
POSSIBLE THAT PATCHY FOG DEVELOPS INLAND AROUND LAKE OKEECHOBEE
TONIGHT AND AGAIN FRIDAY NIGHT. HOWEVER, CHANCES OF THAT ARE BEST
FRIDAY NIGHT AS BY THEN RETURN FLOW FROM THE ATLANTIC WOULD HAVE
HAD MORE TIME TO MOISTEN UP THE LOW LEVELS A BIT. BUT GIVEN ALL
MOS GUIDANCE DEVELOP IT TONIGHT ALSO, I PUT IT IN THE GRIDS.
OVERALL TONIGHT WILL BE THE COOLEST NIGHT OF THE COMING WEEK. A
CAVEAT HERE IS THAT THE MET GUIDANCE IS SIGNIFICANTLY WARMER THAN
THE MAV FOR NORTHEAST PORTIONS OF THE AREA (PALM BEACH COUNTY). NAM
IS BANKING ON LOT OF CLOUDS RETURNING QUICKLY WITH LOW LEVEL FLOW
SHIFTING FROM THE NE. BUT AT THIS TIME DECIDED TO STICK WITH MAV.
FLOW WILL NOT BE THAT STRONG AND A LAND BREEZE COULD PREVENT THIS
SCENARIO FROM HAPPENING TOO. EKDMOS ENSEMBLE GUIDANCE ALSO SHOWS A
MEAN IN THE MID TO UPPER 50S.
SO WITH THAT SAID, TEMPS TONIGHT WILL STILL BE A COUPLE OF DEGREES
ABOVE NORMAL ACROSS SOUTH FLORIDA WITH A WARMING TREND IN STORE FOR
THE UPCOMING WEEKEND AND INTO THE FIRST PART OF NEXT WEEK WHEN
MODELS GENERALLY AGREE ON HIGH PRESSURE ALOFT BUILDING FROM THE
SOUTHERN GULF OF MEXICO ACROSS CUBA AND INTO THE BAHAMAS, KEEPING
JET STREAM AND STORM TRACKS WELL TO OUR NORTH. GFS IS THE MOST
AGGRESSIVE OF THE MODELS BUILDING THE AFOREMENTIONED HIGH ALOFT BUT
THE MEAN OF THE ENSEMBLE IS STILL CONSISTENT WITH THE SCENARIO AND
SO IS THE ECMWF. BOTTOM LINE, THE ENSUING WARMING TREND WILL RESULT
IN OVERNIGHT LOWS RUNNING CLOSE TO 10 DEGREES ABOVE NORMAL BY LATE
IN THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK ALONG WITH
DAYTIME HIGHS RUNNING AROUND 5 DEGREES ABOVE NORMAL.
IT WILL REMAIN DRY FOR THE MOST PART THROUGH THE WEEKEND WITH A
SLIGHT CHANCE OF SHOWERS MAY BE COMING BACK INTO THE PICTURE BY THE
EARLY TO MIDDLE PART OF NEXT WEEK AS LOW LEVEL MOISTURE SLOWLY
RETURNS FROM THE SOUTH BUT NOT LOOKING TOO PROMISING AT THIS TIME.
MARINE...
A BRIEF SURGE IN WIND OF UP TO 15 TO 20 KNOTS TODAY OFF THE COAST
OF PALM BEACH FROM THE NORTH NORTHEAST WILL RESULT IN A SHORT
LIVED SURGE IN SEAS OF UP TO 6 FEET IN THE GULF STREAM. SO WILL
PUT UP A SMALL CRAFT SHOULD EXERCISE CAUTION FOR THOSE WATERS
TODAY. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW 10 TO 15 KNOTS
AND BELOW 4 FEET INTO THE EARLY PART OF NEXT WEEK.
FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES TODAY WILL BE BELOW 35 PERCENT IN
AREAS NORTH OF ALLIGATOR ALLEY ACROSS NORTHERN COLLIER, HENDRY,
AND GLADES COUNTIES TODAY FOR CLOSE TO 4 HOURS. HOWEVER ERC VALUES
ACROSS THE AREA REMAIN TOO LOW FOR ANY RED FLAG CONCERNS. AFTER
TODAY, LOW LEVEL MOISTURE WILL BE ON THE INCREASE AND SO NO OTHER
FIRE CONCERNS AT THIS TIME INTO EARLY NEXT WEEK AT THE VERY LEAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 74 55 76 61 / - - - -
FORT LAUDERDALE 75 61 77 66 / - - - -
MIAMI 76 60 77 65 / - - - -
NAPLES 73 52 78 57 / - - - -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...52/PS
AVIATION/RADAR...15/JR
AREA FORECAST DISCUSSION
NWS LINCOLN IL
543 AM CST THU JAN 19 2012
.DISCUSSION...
ISSUED 245 AM CST THU JAN 19 2012
SHARP ARCTIC COLD FRONT IS ABOUT TO MOVE INTO THE NORTHWEST TIP OF
THE CWA AT 08Z...OVERALL EXTENDING FROM EAST CENTRAL WISCONSIN TO
AROUND KANSAS CITY. TEMPERATURES QUICKLY DROP OFF INTO THE SINGLE
DIGITS AS CLOSE AS CENTRAL IOWA. AREA OF LIGHT SNOW SO FAR HAS
MAINLY BEEN BEHIND THE FRONT. UPSTAIRS...VERY TIGHT UPPER FLOW
CONTINUES...WITH EVENING UPPER AIR ANALYSIS SHOWING A SCREAMING
150+ KNOT JET AT 300 MB FROM AROUND SEATTLE SOUTHEAST INTO
MISSOURI.
MAIN FORECAST CHALLENGE WITH THIS PACKAGE IS WITH PRECIPITATION
TYPES FRIDAY AND FRIDAY NIGHT. THE EFFECTS OF THE CURRENT SYSTEM
ARE A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
LATEST HRRR MODEL SWEEPS THE FRONT ACROSS THE CWA THIS MORNING...
LINGERING THROUGH MIDDAY ACROSS THE FAR SOUTHEAST. BEST LIFT WITH
THIS FRONT IS STILL EXPECTED OVER THE NORTHEAST THIRD OF THE
CWA...WITH 1-2 INCHES OF SNOW EXPECTED NORTH OF A BLOOMINGTON TO
DANVILLE LINE THROUGH EARLY AFTERNOON. SHARP SOUTHERN CUTOFF TO
THE SNOW IS EXPECTED...AND WENT WITH ONLY SLIGHT CHANCES SOUTH OF
A JACKSONVILLE TO TERRE HAUTE LINE. ONLY THE SOUTHEAST CWA IS
EXPECTED TO SEE TEMPERATURES RISE ABOVE FREEZING...WITH MOST OF
THE FORECAST AREA SEEING FALLING DAYTIME TEMPERATURES.
THE FRIDAY STORM SYSTEM CONTINUES TO HAVE SEPARATE CONCERNS...ONE
WITH THE SNOW ACROSS THE NORTH IN THE STRONGER LIFT AND BAROCLINIC
ZONE...AND THE POTENTIAL FOR MIXED PRECIPITATION FURTHER SOUTH
CLOSER TO THE SURFACE FEATURES. SNOW-WISE...BEST LIFT STILL
EXPECTED JUST TO OUR NORTH ACROSS NORTHERN ILLINOIS...BUT 2-3
INCHES IS LIKELY AS FAR SOUTH AS GALESBURG AND PEORIA FRIDAY INTO
FRIDAY EVENING. FURTHER SOUTH...FORECAST SOUNDINGS SHOWING A
WEDGE OF WARM AIR AROUND 900 MB MOVING IN LATER FRIDAY AFTERNOON
AND ESPECIALLY DURING THE EVENING. THE NAM IS MOST PRONOUNCED WITH
THIS AROUND CHAMPAIGN AND MATTOON...WHILE THE GFS IS FURTHER SOUTH
TOWARD LAWRENCEVILLE AND THE LOCAL WRF IN BETWEEN. EVAPORATIVE
COOLING WOULD FAVOR MORE OF A SLEET/SNOW MIXTURE INITIALLY...THEN
SOME FREEZING RAIN AND SLEET IN THE EVENING BEFORE SWITCHING OVER
TO SNOW LATE TONIGHT. WILL INCLUDE SOME LOW ICE ACCUMULATIONS IN
AREAS MAINLY BETWEEN I-72 AND I-70...WITH LOCATIONS FROM MATTOON
TO PARIS WITH THE HIGHEST AMOUNTS OF AROUND 0.05 INCH OR SO. MAY
NEED TO CONSIDER WINTER WEATHER ADVISORIES IN SOME PARTS OF THE
CWA...BUT ENOUGH MODEL VARIABILITY EXISTS TO PRECLUDE ISSUING ONE
AT THIS TIME.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
PRECIPITATION TO BE OUT OF THE AREA BEFORE SUNRISE SATURDAY...WITH
HIGH PRESSURE RESULTING IN DRY WEATHER. FOCUS IN THE LONGER TERM
SHIFTS TO A DIGGING SHORTWAVE WHICH WILL CROSS THE MIDDLE OF THE
NATION SUNDAY NIGHT AND MONDAY. FOLLOWED THE SLOWER ECMWF/CANADIAN
SOLUTIONS...WHICH FAVOR RAIN FOR THE MOST PART AND A CHANGEOVER TO
SNOW AS THE PRECIPITATION ENDS SUNDAY NIGHT. MODEL SOLUTIONS ARE
CLOSER TO EACH OTHER ON THE NEXT WAVE WHICH CROSSES MIDWEEK...WITH
THE NEXT SHOT OF PRECIPITATION.
ASIDE FROM THE COLD START TO THE WEEKEND...TEMPERATURES MUCH OF
THIS PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL.
GEELHART
&&
.AVIATION...
ISSUED 543 AM CST THU JAN 19 2012
CONDITIONS WILL BE PRIMARILY VFR AT ALL TAF SITES THROUGH THE
PERIOD. A QUICK MOVING WINTER SYSTEM WILL BRING TEMPO SNOW/MVFR
CIGS/VIS TO PIA/BMI/CMI THIS MORNING THROUGH ABOUT NOON...WHILE
SPI/DEC JUST WILL HAVE VCSH AND SCATTERED AT 2.5KFT. ONCE SYSTEM
PASSES CLOUDS HEIGHTS WILL RISE AGAIN AND WILL BE LEFT WITH JUST
CIRRUS CLOUDS FROM THIS AFTERNOON THROUGH TONIGHT. WINDS WILL BE
SOUTHWEST AHEAD OF THE FRONT BUT QUICKLY SWITCH TO NORTHWEST
BEHIND THE FRONT. EXPECT NORTHERLY WINDS THIS AFTERNOON THROUGH
THIS EVENING...BECOMING NORTHEAST OVERNIGHT. TIGHT TEMP GRADIENT
BEHIND FRONT WILL BRING SOME STRONGER WINDS...BUT GRADIENT WEAKENS
A FEW HOURS BEHIND THE FRONT SO WINDS WILL DECREASE REST OF THE
PERIOD.
AUTEN
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
425 AM MST THU JAN 19 2012
.DISCUSSION...
220 AM MST THU JAN 19 2012
EARLY MORNING WV IMAGERY AND RUC H5 ANALYSIS SHOW BROAD TROUGH
EXTENDING FROM GREAT LAKES ACROSS THE EASTERN US...WITH W/NW FLOW
EXTENDING ACROSS THE CENTRAL PART OF THE COUNTRY. AT THE SURFACE A
STRONG COLD FRONT HAS SETTLED OVER THE CWA...WITH A 20F SPREAD IN
TEMPS BETWEEN THE SW PART OF THE CWA AND THE NE.
TODAY-SATURDAY...WITH DRY CONDITIONS EXPECTED THE MAIN FORECAST
CONCERN WILL CONTINUE TO BE TEMPERATURES AS THE PREVIOUSLY MENTIONED
FRONT AND ASSOCIATED BAROCLINIC ZONE LINGERS ACROSS PORTIONS OF
NORTHWEST KANSAS AND SOUTHWEST NEBRASKA. 30F SPREAD IN HIGH TEMPS
CURRENTLY FORECAST FROM THE EAST TO THE WEST TODAY...WITH AREAS WEST
OF THE FRONT APPROACHING THE MID 50S...AND EAST OF THE FRONT IN THE
MID/UPPER 20S. BETWEEN THESE EXTREMES IT IS DIFFICULT TO PIN DOWN
HIGH TEMPS CONSIDERING THE EXTREME TEMPERATURE GRADIENT THAT
WILL BE IN PLACE...SO HAVE USED A GENERAL BLEND OF PREVIOUS FORECAST
AND LATEST SHORT-RANGE GUIDANCE. TEMPS WILL BEGIN TO MODERATE SOME
ACROSS EASTERN PARTS OF THE AREA FRIDAY...BEFORE A BACKDOOR COLD
FRONT REINFORCES SHALLOW COLD AIR MASS FRIDAY AFTERNOON/EVENING.
SHALLOW COLD AIR MASS BEGINS TO SCOUR OUT WITH TEMPS MODERATING
AHEAD OF SHORTWAVE TROUGH MOVING TOWARDS THE GREAT BASIN...THOUGH
THERE WILL STILL BE A 15-20F GRADIENT FROM EAST TO WEST.
SATURDAY NIGHT...SHORTWAVE TROUGH MOVES TOWARDS THE CENTRAL ROCKIES
SATURDAY NIGHT...WITH INCREASING LARGE SCALE ASCENT OVER THE CWA
AFTER 06Z. NAM/GFS BOTH ARE WEAKER/QUICKER WITH THIS SYSTEM...AND
KEEP CONDITIONS DRY OVER CWA. ECMWF CONTINUES TO SHOW
STRONGER/WETTER SOLUTION. I WAS HESITANT TO JUMP ON THE WET ECMWF
SOLUTION YET...WITH TIMING/STRENGTH STILL IN QUESTION. WITH THE
AMOUNT OF LIFT PRESENT AND LIMITED MOISTURE ADVECTION I COULDNT RULE
OUT SOME FLURRIES IN THE NORTH...BUT WASNT CONFIDENT ENOUGH TO ADD
DURING THIS CYCLE.
DR
FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...RELATIVELY QUIET WEATHER
EXPECTED THROUGH THE ENTIRE PERIOD. A COLD FRONT WILL MOVE THROUGH
THE REGION MONDAY NIGHT AND TUESDAY...HOWEVER PRECIPITATION CHANCES
APPEAR THEY WILL STAY SOUTH AND EAST OF THE LOCAL FORECAST AREA. IT
WILL BRING A PERIOD OF GUSTY NORTH WINDS...PROBABLY TUESDAY
MORNING....AND COOLER TEMPERATURES TUESDAY AND WEDNESDAY...ALBEIT
STILL ABOVE NORMAL.
024
&&
.AVIATION...
425 AM MST THU JAN 19 2012
FOR THE 12Z TAFS...ARCTIC FRONT CONTINUES TO SETTLE INTO THE AREA
FROM THE NORTHEAST. LIGHT WINDS WILL VEER FROM NORTHEAST TO
SOUTHEAST AT KMCK...AND NORTHEAST TO SOUTHWEST AT KGLD THROUGH THIS
AFTERNOON. SCATTERED TO BROKEN HIGH CLOUDS WILL CONTINUE TO STREAM
OVERHEAD. /024
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
509 AM CST THU JAN 19 2012
.AVIATION...
FOR THE 12Z TAF ISSUANCE...
AT 9Z A COLD FRONT EXTENDED ACROSS SOUTHWEST KANSAS WITH THE NAM
AND RUC APPEARING TO BE DOING A DECENT JOB WITH THIS SURFACE FRONT
LOCATION. THEY ALSO APPEAR TO BE HANDLING THE TIGHT PRESSURE
GRADIENT/GUSTY WINDS THAT HAD APPEARED AT A FEW OBSERVATION SITES
IN NORTH CENTRAL KANSAS EARLIER THIS MORNING. WILL THEREFORE
CONTINUE TO FOLLOW THE NAM AND RUC SOLUTIONS ON TIMING OF THIS
FRONT/WIND SHIFT AS IT CROSSES THE REMAINDER OF SOUTHWEST KANSAS.
FOLLOWING THE WIND SHIFT A BRIEF PERIOD OF GUSTY WINDS WILL THEN
DEVELOP BUT THESE WINDS WILL START TO SUBSIDE BY MID MORNING AS AN
AREA OF HIGH PRESSURE BEGINS TO BUILD INTO THE AREA FROM THE
NORTH. SURFACE WINDS AT 10KTS OR LESS ARE THEN EXPECTED THROUGH
THE REMAINDER OF THE AFTERNOON. THE NORTH/NORTHEAST WINDS WILL
GRADUALLY SHIFT TO THE SOUTHEAST EARLY TONIGHT AS OUR SURFACE HIGH
MOVES NORTHEAST OF THE AREA.
BY 06Z FRIDAY BUFR SOUNDINGS SUGGESTING 45KT WINDS WILL DEVELOP
JUST ABOVE THIS COLD LAYER AND THE 0-0.5KM WIND SHEAR IS FORECAST
TO BE AROUND 40KTS. AS A RESULT WILL INTRODUCE A WIND SHEAR GROUP
INTO THE TAFS AT 06Z.-RB
&&
.PREV DISCUSSION... /ISSUED 328 AM CST THU JAN 19 2012/
SYNOPSIS...
PAST EVENING UPPER AIR DATA ALONG WITH RECENT WATER VAPOR IMAGERY
REVEALS A VERY BROAD TROUGH OVER THE EASTERN HALF OF THE COUNTRY
WHILE AN EQUALLY EXTENSIVE RIDGE EXTENDS OVER THE WEST. EMBEDDED
WITHIN THIS FLOW REGIME IS A 140+ KNOT UPPER JET STREAK THAT EXTENDS
FROM THE PACIFIC NORTHWEST REGION INTO THE DEEP SOUTH. CLOSER TO THE
SURFACE, A LARGE RESERVOIR OF ARCTIC AIR ACROSS CANADA IS INVADING
THE NORTHERN PLAINS WITH 00 UTC 850 HPA PLOTS DISPLAYING A LARGE
POCKET OF -30C AIR OVER NORTH DAKOTA INTO EASTERN MONTANA. RECENT
SUBJECTIVE SURFACE ANALYSIS DISPLAYS THE ARCTIC FRONT SINKING
SOUTHWARD OVER KANSAS WITH TEMPERATURES DROPPING QUICKLY INTO THE
SINGLE DIGITS OVER CENTRAL AND NORTHERN NEBRASKA. DETERMINISTIC
MODEL GUIDANCE INITIALIZED AT 00 UTC BUT VALID AT 06 UTC IS RUNNING
AROUND 5 TO 10 DEGREES TOO WARM BEHIND THE FRONT. THIS STRONGLY
INDICATES ANY BOUNDARY LAYER BASED MODEL THERMAL FIELDS ARE TOO WARM
FOR THIS MORNING TO AFTERNOON AS WELL.
DISCUSSION...
DAYS 1-2...
THE UPPER PATTERN WILL CHANGE LITTLE TODAY INTO THE FIRST HALF OF
TONIGHT AS A TROUGH DOMINATES OVER THE EASTERN HALF OF THE COUNTRY
WHILE A RIDGE PREVAILS OVER THE WEST. WITH THE STRONGEST FORCING
REMAINING WELL NORTH OF KANSAS, DRY CONDITIONS WILL CONTINUE OVER
THE CENTRAL PLAINS. NONETHELESS, AGEOSTROPHIC FLOW ASSOCIATED WITH
THE ENTRANCE REGION OF THE AFOREMENTIONED JET STREAK, WILL ALLOW THE
ARCTIC FRONT TO SLIDE SOUTHWARD INTO FAR NORTHERN OKLAHOMA AND
EXTREME SOUTHWEST KANSAS BY MID MORNING. ALTHOUGH THE AIRMASS WILL
REMAIN RELATIVELY SHALLOW WITH 850 HPA TEMPERATURES STAYING
GENERALLY ABOVE 3C TO 5C...STRONG COLD AIR ADVECTION IN THE LOWER
500 METERS WILL KEEP SURFACE TEMPERATURES RELATIVELY COLD TODAY OVER
MOST OF WESTERN AND CENTRAL KANSAS. HOWEVER, THE MAIN QUESTION IS
WHERE THE FRONT WILL EXTEND OVER EXTREME SOUTHWEST KANSAS AS THE
TEMPERATURE GRADIENT WILL BE TIGHT. LOCATIONS SOUTHWEST OF THE
BOUNDARY WILL EXPERIENCE LIGHT WEST WINDS WITH TEMPERATURES IN THE
MID 50S TO LOWER 60S WHILE LOCATIONS A GOOD 60 MILES AWAY FROM THE
FRONT BUT ON THE COOL SIDE OF THE BOUNDARY WILL SEE TEMPERATURES IN
THE MID 20S TO MID 30S. A NARROW 40 TO 50 MILE CORRIDOR WILL ACT AS
A BUFFER ZONE BETWEEN THESE TWO EXTREMES WITH TEMPERATURES IN THE
UPPER 30S TO 40S EXPECTED...BUT WHERE THIS ZONES SETS UP IS SIMPLY A
GUESS AT THIS POINT. WILL AIM FOR A GARDEN CITY TO COLDWATER LINE
WITH HIGHS VARYING FROM THE MID 20S AROUND HAYS, THE UPPER 30S IN
DODGE, AND NEAR 60 AROUND ELKHART.
LATER TONIGHT INTO FRIDAY NIGHT...A SMALL BUT POTENT UPPER WAVE WILL
UNDERCUT THE RIDGE AXIS AND PLOW INTO THE CENTRAL ROCKIES BY LATE
FRIDAY AFTERNOON. ALTHOUGH THE ATMOSPHERE WILL BE TOO DRY FOR THIS
WAVE TO PRODUCE ANY REAL THREAT FOR PRECIPITATION, IT WILL ALLOW A
REINFORCING SHOT OF ARCTIC AIR TO INVADE WESTERN AND CENTRAL KANSAS
BY LATE MORNING TO EARLY AFTERNOON. HOWEVER, IN ADVANCE OF THIS
FRONT PRESSURE FALLS ALONG THE FRONT RANGE REGION WILL BEGIN TO VEER
WINDS AROUND TO A MORE WESTERLY DIRECTION BY SUNRISE ON FRIDAY. THIS
MAY ALLOW FOR SOME MODEST WARM AIR ADVECTION DURING THE EARLY TO MID
MORNING BEFORE COLDER AIR INVADES WESTERN AND CENTRAL KANSAS YET AGAIN.
THE THINKING AS OF NOW IS THAT DOWNSLOPE WESTERLY WINDS WILL SPREAD
AS FAR EAST AS A SCOTT CITY TO COLDWATER LINE BEFORE COLD AIR
ARRIVES IN THE LATE MORNING TO EARLY AFTERNOON. THIS MAY RESULT IN
TEMPERATURES BRIEFLY SPIKING INTO THE MID 40S TO MID 50S WEST OF THE
ABOVE LINE BUT THEN FALLING DURING THE AFTERNOON HOURS. LOCATIONS
EAST OF THIS LINE SHOULD STAY IN THE 30S. OTHERWISE, A COLD EVENING
TO OVERNIGHT WILL PREVAIL AS COLDER AIR SPILLS OVER THE CENTRAL
PLAINS. ANTICIPATE TEMPERATURES DROPPING INTO A 10 TO 20 DEGREE
RANGE AFTER MIDNIGHT.
DAYS 3-7...
A TIGHT BAROCLINIC ZONE WILL ESTABLISH ITSELF ACROSS PORTIONS OF
WESTERN KANSAS ON SATURDAY BETWEEN THE COLDER AIR THAT WILL INVADE
THE STATE FRIDAY NIGHT AND THE DOWNSLOPE WARMING THAT IS ANTICIPATED
TO SPREAD INTO THE AREA FROM THE WEST BY SATURDAY AFTERNOON. THE
CURRENT FORECAST WITH HIGHS ONLY IN THE MID 30S ACROSS PORTIONS OF
NORTH CENTRAL KANSAS STILL APPEARS ON TRACK GIVEN THE LATEST MODELS
SOUNDINGS. FURTHER WEST 850MB TEMPERATURES INDICATING HIGHS NEAR 60
STILL WILL BE POSSIBLE AS THE 925-850MB TEMPERATURES BEGIN TO WARM.
WILL HOWEVER NEED TO MONITOR THE AMOUNT OF HIGHS CLOUDS DURING THE
DAY AS BOTH THE ECMWF AND GFS 300-200MB RELATIVE HUMIDITIES
INCREASES ACROSS WESTERN KANSAS DURING THE AFTERNOON. THIS CLOUD
COVER WILL PRECEDE AN UPPER LEVEL TROUGH WHICH AT 00Z SUNDAY IS
EXPECTED TO BE LOCATED ACROSS UTAH. THIS NEXT SYSTEM WILL QUICKLY
MOVE EAST INTO THE WEST CENTRAL HIGH PLAINS ON SUNDAY AS MID-HIGH
LEVEL MOISTURE CONTINUES TO INCREASE. THIS INCREASE IN MOISTURE
ALONG WITH IMPROVING MID LEVEL INSTABILITY MAY ALSO GIVE RISE TO
SOME VIRGA, MAYBE EVEN A FEW SPRINKLES NEAR THE INTERSTATE 70
CORRIDOR. AT THIS TIME CONFIDENCE IS NOT HIGH ENOUGH YET TO INSERT
MENTION OF LIGHT PRECIPITATION IN OUR NORTH BUT DID INCREASE CLOUD
COVER AND LOWER TEMPERATURES.
BY EARLY NEXT WEEK A SHORT WAVE RIDGE WILL QUICKLY CROSS THE ROCKIES
AND MOVE OUT INTO THE PLAINS AS OUR NEXT PACIFIC UPPER LEVEL TROUGH
STARTS TO WORK ITS WAY EASTWARD ACROSS THE WESTERN UNITED STATES.
ONCE AGAIN MID LEVEL MOISTURE IMPROVES AS 700-500MB LAPSE RATES
INCREASE. THIS WILL ONCE AGAIN BRING AN INCREASE IN CLOUDS AND
POSSIBLY SOME LIGHT PRECIPITATION ON TUESDAY TO PARTS OF SOUTHWEST
KANSAS IF THE GFS IS CORRECT. AGAIN CONFIDENCE IS NOT HIGH ON
PRECIPITATION CHANCES GIVEN THE HEIGHT OF WHERE THE BETTER MOISTURE
RETURN IS ANTICIPATED. HAVE THEREFORE DECIDED TO LEAVE THE SMALL
15-20PERCENT CHANCE OF RAIN GOING FOR OUR SOUTH/SOUTHEAST BUT DID
NOT EXPAND THE CHANCES ANY FURTHER NORTH.
AVIATION...
FOR THE 06Z TAF ISSUANCE...
THERE ISN`T A GREAT DEAL OF CHANGE IN THINKING FOR THIS TAF
ISSUANCE. THE FRONT IS EXPECTED TO MOVE THROUGH HAYS (HYS) AT
07Z...THEN ROUGHLY 0830Z AT DODGE CITY (DDC) AND FINALLY SHORTLY
THEREAFTER AT GARDEN CITY (GCK) AROUND 09Z. THERE WILL BE SEVERAL
HOURS OF GUSTS IN THE LOW 20S KTS...BUT THE WINDS WILL GRADUALLY
DECREASE DURING THE 15-18Z TIME FRAME...WITH A CONTINUE DECREASE
TO LESS THAN 10 KNOTS FOR SOME TIME MIDDAY THROUGH EARLY
AFTERNOON. THE WINDS WILL THEN CONTINUE TO VEER AROUND TO THE
SOUTHEAST LATE IN THE DAY WITH A GRADUAL INCREASE BACK TO AROUND
12 KNOTS OR SLIGHTLY HIGHER IN RESPONSE TO RENEWED LEESIDE
CYCLOGENESIS OVER EASTERN COLORADO. THE PROBABILITY OF STRATUS
DEVELOPMENT IS VERY LOW GIVEN HOW SHALLOW THE ARCTIC AIRMASS IS
AND HOW DRY THE LOWER ATMOSPHERE IS AS WELL.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 39 22 48 18 / 0 0 0 0
GCK 41 23 49 17 / 0 0 0 0
EHA 60 35 56 26 / 0 0 0 0
LBL 54 27 57 20 / 0 0 0 0
HYS 26 16 36 11 / 0 0 0 0
P28 39 24 46 19 / 0 0 0 0
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
FN99/99/99
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
819 AM EST THU JAN 19 2012
.SYNOPSIS...
A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW
THIS AFTERNOON INTO EARLY TONIGHT. LOW PRESSURE, COMING NORTHEAST
FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY
MIX FOR FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RECENT HRRR MODEL OUTPUT CONTINUES TO SHOW FRONTAL BAND OF SNOW
WILL BEGIN SPREADING SOUTHEASTWARD ACROSS THE UPPER OHIO VALLEY
DURING MIDDAY. TEMPERATURES NORTH WILL LIKELY NOT GET WARMER THAN
FREEZING BEFOREHAND, WHILE TEMPERATURES SOUTH WILL. ONCE PRECIPITATION
BEGINS, ALL TEMPERATURES WILL DROP TO BELOW FREEZING, HENCE THIS
SHOULD BE AN ALL SNOW EVENT.
CONTINUE TO EXPECT SNOW AMOUNTS FOR MOST PLACES TO BE AROUND 2
INCHES, POSSIBLY MORE NORTH. WILL MAINTAIN CURRENT WINTER WEATHER
ADVISORIES NORTH, AND MAY CONSIDER EXPANSION SOUTH, DUE TO POTENTIAL
OF HAZARDOUS IMPACTS WITH TEMPERATURES NEAR FREEZING AND SNOWFALL
CONTINUING PAST THE EVENING COMMUTER RUSH.
HIGH PRESSURE WILL BUILD IN THE WAKE OF THE FRONT TONIGHT AND
GRADUALLY END THE SNOW. TEMPERATURES WERE FORECAST A FEW DEGREES
UNDER THE SEASONAL AVERAGES USING TWEAKED NAMDNG5 NMBRS.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE
FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST
DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE
PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST
IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND
FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE
OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF
PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR
THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK
FOR THESE POTENTIALS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE
DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY.
AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW
ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE
ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO
CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW.
DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH
MOVES EASTWARD INTO THE OHIO VALLEY.
STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE
NORMAL THROUGH THE EXTENDED PERIOD.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
VFR FORECAST INTO THE AFTERNOON. AFTER DAWN, THERE WILL BE IN AN
INCREASE IN MID DECK CLOUD COVER AS WELL AS STRENGTHENING SW SFC
WINDS, WITH SOME GUSTS TO 20 KTS BY MIDDAY.
COLD FRONT WILL REACH THE WESTERN EDGE OF THE AREA AROUND 20Z. MVFR
TO IFR RESTRICTIONS WITH SNOW AND LOW CLOUDS EXPECTED AT ALL
PORTS DURING THE AFTERNOON AND EVENING HOURS.
OUTLOOK...TONIGHT NIGHT THROUGH MONDAY...
RESTRICTIONS WITH SNOW AND LOW CLOUDS WILL CONTINUE THROUGH THIS
EVENING. VIS SHOULD QUICKLY IMPROVE AFTER 06Z AS AREA OF SNOW
SHOWERS MOVES SOUTHEAST.
VFR CONDITIONS WILL BRIEFLY RETURN FRIDAY AS A SURFACE HIGH SLIDES
ACROSS THE REGION. A SYSTEM TRACKING SOUTH OF THE AREA WILL BRING A
WINTRY MIX WITH RESTRICTIONS FRIDAY NIGHT AND SATURDAY. AFTER A
PERIOD OF VFR WEATHER SUNDAY, AN APPROACHING FRONT IS PROGGED TO
SPREAD SCATTERED RAIN SHOWERS AND RESTRICTIONS ACROSS THE TERMINALS
MONDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT EST
TONIGHT FOR PAZ007>009-013>016-022-023.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
808 AM EST THU JAN 19 2012
.SYNOPSIS...
ACCUMULATING SNOW SHOWERS CAN BE EXPECTED TODAY AS A FAST MOVING
COLD FRONT CROSSES THE UPPER OHIO VALLEY REGION. LOW PRESSURE,
COMING NORTHEAST FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING
A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
RECENT HRRR MODEL OUTPUT CONTINUES TO SHOW FRONTAL BAND OF SNOW
SHOWERS WILL BEGIN SPREADING SOUTHEASTWARD ACROSS THE UPPER OHIO
VALLEY DURING MIDDAY. TEMPERATURES NORTH WILL LIKELY NOT GET
WARMER THAN FREEZING, WHILE TEMPERATURES SOUTH WILL. ONCE
PRECIPITATION BEGINS, ALL TEMPERATURES WILL DROP TO BELOW
FREEZING, HENCE THIS SHOULD BE AN ALL SNOW EVENT.
CONTINUE TO EXPECT SNOW AMOUNTS FOR MOST PLACES TO BE AROUND 2
INCHES, POSSIBLY MORE NORTH. WILL MAINTAIN CURRENT WINTER WEATHER
ADVISORIES NORTH, AND MAY CONSIDER EXPANSION SOUTH, CONTINUING POTENTIAL
OF HAZARDOUS IMPACTS WITH TEMPERATURES NEAR FREEZING AND SNOWFALL
CONTINUING PAST THE EVENING COMMUTER RUSH.
HIGH PRESSURE WILL BUILD IN THE WAKE OF THE FRONT TONIGHT AND
GRADUALLY END THE SNOW. TEMPERATURES WERE FORECAST A FEW DEGREES
UNDER THE SEASONAL AVERAGES USING TWEAKED NAMDNG5 NMBRS.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE
FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST
DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE
PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST
IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND
FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE
OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF
PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR
THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK
FOR THESE POTENTIALS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE
DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY.
AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW
ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE
ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO
CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW.
DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH
MOVES EASTWARD INTO THE OHIO VALLEY.
STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE
NORMAL THROUGH THE EXTENDED PERIOD.
&&
.AVIATION /13Z THURSDAY THROUGH MONDAY/...
VFR FORECAST INTO THE AFTERNOON. AFTER DAWN, THERE WILL BE IN AN
INCREASE IN MID DECK CLOUD COVER AS WELL AS STRENGTHENING SW SFC
WINDS, WITH SOME GUSTS TO 20 KTS BY MIDDAY.
COLD FRONT WILL REACH THE WESTERN EDGE OF THE AREA AROUND 20Z. MVFR
TO IFR RESTRICTIONS WITH SNOW SHOWERS AND LOW CLOUDS EXPECTED AT ALL
PORTS DURING THE AFTERNOON AND EVENING HOURS.
OUTLOOK...TONIGHT NIGHT THROUGH MONDAY...
RESTRICTIONS WITH SNOW AND LOW CLOUDS WILL CONTINUE THROUGH THIS
EVENING. VIS SHOULD QUICKLY IMPROVE AFTER 06Z AS AREA OF SNOW
SHOWERS MOVES SOUTHEAST.
VFR CONDITIONS WILL BRIEFLY RETURN FRIDAY AS A SURFACE HIGH SLIDES
ACROSS THE REGION. A SYSTEM TRACKING SOUTH OF THE AREA WILL BRING A
WINTRY MIX WITH RESTRICTIONS FRIDAY NIGHT AND SATURDAY. AFTER A
PERIOD OF VFR WEATHER SUNDAY, AN APPROACHING FRONT IS PROGGED TO
SPREAD SCATTERED RAIN SHOWERS AND RESTRICTIONS ACROSS THE TERMINALS
MONDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT EST
TONIGHT FOR PAZ007>009-013>016-022-023.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
639 AM CST THU JAN 19 2012
.UPDATE...JUST RAN A QUICK UPDATE TO TABULAR AFM/PFM PRODUCTS AND
WEB-BASED PRODUCTS TO BRING NEXT SEVERAL HOURS OF TEMP/DEWPOINT
TRENDS MORE IN LINE WITH CURRENT OBS...AS COLDER AND DRIER AIR HAS
PUSHED MORE AGGRESSIVELY SOUTHWARD INTO SOUTHERN PORTIONS OF THE
CWA THAN EXPECTED EVEN A FEW HOURS AGO. ONLY MODEL/GUIDANCE REALLY
PROVING USEFUL FOR THESE VERY SHORT TERM TRENDS IS GFS LAMP
GUIDANCE. WIND CHILLS BETWEEN -10 AND -15 WILL BE WIDESPREAD
ACROSS MOST ALL NEB ZONES FOR THE NEXT FEW HOURS...WITH KS ZONES
MORE SO -5 TO -10. ALTHOUGH NO CHANGES WERE MADE TO AFTERNOON HIGH
TEMPS AT THIS TIME...INTERESTING TO NOTE THAT BOTH THE 09Z RUC AND
HRRR SUGGEST THAT THE TRI-CITIES WILL RECOVER ENOUGH TO POSSIBLY
REACH 20 THIS AFTERNOON...BUT THIS SEEMS TOO OPTIMISTIC AT THIS
TIME AND WILL STICK WITH GOING FORECAST.
&&
.PREV DISCUSSION... /ISSUED 600 AM CST THU JAN 19 2012/
AVIATION...12Z TAF. ARCTIC HIGH PRESSURE WILL SHIFT INTO NORTHERN
IOWA TODAY. NORTHEASTERLY WINDS THIS MORNING WILL BECOME VARIABLE
FOR A FEW HOURS AROUND MIDDAY BEFORE TRANSITIONING TO THE
SOUTHEAST. CLOUD COVER LOOKS TO BE LIMITED TO THE MID AND HIGH
LEVELS FOR MUCH OF THE DAY WITH SOME MVFR TO VFR CIGS POSSIBLE
LATER TONIGHT OR TOWARD FRIDAY MORNING.
PREV DISCUSSION... /ISSUED 451 AM CST THU JAN 19 2012/
SHORT TERM...THROUGH SATURDAY NIGHT. PRIMARY CONCERN DURING THE
NEXT 72 HOURS CONTINUES TO BE TEMPERATURE TRENDS...WITH THE NEXT
REGIONAL SNOW EVENT FROM THURSDAY NIGHT INTO FRIDAY STILL PROGGED
TO MISS MOST...IF NOT ALL OF THE CWA TO THE NORTHEAST...FOCUSING
ALONG AN AXIS FROM SD THROUGH NORTHEAST NEB/NORTHERN IA. THAT
BEING SAID...ALTHOUGH NOT OVERLY CONCERNED AT THIS POINT...WILL
NEED TO MONITOR LOW LEVEL MOISTURE TRENDS CLOSELY LATE THURS NIGHT
INTO FRIDAY MORNING TO MAKE SURE THAT NO LIGHT FREEZING DRIZZLE
TRIES TO SNEAK UP ON US.
09Z OBJECTIVE SURFACE ANALYSIS REVEALS THAT THE WELL ADVERTISED
ARCTIC COLD FRONT HAS MADE STEADY PROGRESS SOUTHWARD ACROSS THE
CWA THROUGH THE NIGHT...PUSHED ALONG BY A BROAD 1024MB HIGH
CENTERED FROM MT TO NORTHERN SD. TEMPERATURES AT 09Z RANGED FROM 2
AT ORD...TO 18 AT BELOIT. ADDING TO THE INVADING BITTERNESS ARE
STEADY NORTH-NORTHEAST BREEZES OF 10-20 MPH...YIELDING WIND CHILL
VALUES RANGING FROM -10 TO -15 NORTH OF I-80...TO NEAR ZERO IN THE
SOUTH. DESPITE PLENTIFUL MID LEVEL RADAR RETURNS EARLIER THE NIGHT
ACROSS THE NORTHEAST...IT IS LIKELY THAT FLURRY ACTIVITY DID NOT
MATERIALIZE ACROSS THE NORTHEAST. ALOFT...WATER VAPOR IMAGERY AND
SHORT TERM MODEL DATA FEATURE VERY FAST NORTHWEST FLOW BISECTING
THE CONUS FROM NORTHWEST TO SOUTHEAST...HIGHLIGHTED BY A 140+KT
300MB JET STREAK CUTTING ACROSS EASTERN NEB. ALTHOUGH THE PRIMARY
MID LEVEL SHORTWAVE/500MB VORT MAX OF NOTE IS ALREADY WELL
NORTHEAST INTO THE GREAT LAKES...LIFT ASSOCIATED WITH THE UPPER
JET STREAK HAS GENERATED PLENTIFUL CIRRUS OVER MAINLY NEB ZONES
OVERNIGHT...BUT KEEPING PRIMARY ZONE OF MID LEVEL
SATURATION/POSSIBLE LIGHT SNOW PRODUCTION OFF TO THE NORTH AND
EAST.
TODAY...THE AFOREMENTIONED STRONG UPPER JET AXIS DRIFTS
NORTHEAST...WITH ITS CENTER ALONG AN AXIS FROM CENTRAL ND TO
NORTHERN IL BY 00Z THIS EVENING. AS A RESULT...THE EXTENSIVE HIGH
LEVEL CLOUD COVER ACROSS MOST OF THE CWA SHOULD GRADUALLY SCATTER
OUT AND/OR LIFT NORTHEAST AS WELL...WITH AT LEAST PARTLY CLOUDY
SKIES ANTICIPATED MOST AREAS FOR THIS AFTERNOON. EVEN IF THE SUN
IS OUT...IT WON/T DO A WHOLE LOT TO MASK WHAT IS ALMOST CERTAINLY
TO BE THE OVERALL COLDEST DAY OF THE WINTER SO FAR FOR MOST OF THE
CWA. AS THE DAY WEARS ON...THE CENTER OF THE SURFACE HIGH WILL
MIGRATE INTO MN/IA...ALLOWING BREEZES TO GRADUALLY DIMINISH INTO
THE 5-10 MPH RANGE FOR THIS AFTERNOON AS THEY GRADUALLY SHIFT FROM
MORE NORTHERLY TO MORE EASTERLY/SOUTHEASTERLY BY LATE IN THE DAY.
AS FOR TEMPS...YET AGAIN OPTED TO LOWER HIGHS BY 2-5 DEGREES FROM
PREVIOUS FORECAST IN MOST AREAS...LEANING TOWARD THE COLDER MAV
GUIDANCE. THIS YIELDS HIGHS RANGING FROM ONLY 10-13 DEGREES IN THE
NORTHEAST CWA...TO MID 20S FAR SOUTH AND WEST WHERE THE SOUTHEAST
FLOW AROUND THE HIGH SHOULD HELP MODERATE THINGS SOMEWHAT. AS FOR
WIND CHILLS THIS MORNING...VALUES WILL CONTINUE TO RANGE BETWEEN
-10 AND -17 ACROSS MUCH OF THE NORTHEAST 1/2 OF THE CWA THROUGH AT
LEAST MID-MORNING...WHICH WILL BE ABOVE ADVISORY CRITERIA OF -20
BUT NOT BY MUCH. ITS CLOSE ENOUGH THAT WILL PUT A MENTION IN THE
HAZARDOUS WEATHER OUTLOOK.
TONIGHT...THE NEXT BATCH OF BROAD...LOW AMPLITUDE SHORTWAVE ENERGY
QUICKLY APPROACHES THE CENTRAL CONUS FROM THE NORTHWEST. WITHIN
THE ENTRANCE REGION OF THE PRIMARY UPPER JET AXIS MIGRATING ACROSS
THE UPPER MISS VALLEY/GREAT LAKES...AN IMPRESSIVE ZONE OF
ISENTROPIC LIFT/MID LEVEL CONVERGENCE WILL SET UP ALONG AND NORTH OF
THE PRIMARY LOW-MID LEVEL TEMPERATURE GRADIENT CENTERED FROM SD
INTO NORTHEAST NEB/IA. THIS WILL BE THE OBVIOUS FOCUS FOR THE
START OF A MEASURABLE SNOW EVENT FOR THOSE AREAS. ALTHOUGH IT IS
SEEMING MORE AND MORE LIKELY THAT THE CWA WILL MISS OUT ON THIS
ACTION...PREVIOUS FORECAST HAD SOME LOW POPS ACROSS THE
NORTHEAST...AND WILL CONTINUE THIS MENTION AFTER MIDNIGHT FOR
MAINLY THE NORTHEAST 1/5 OF THE CWA JUST IN CASE THE FAR SOUTHERN
EDGE OF THIS ACTIVITY SLIPS IN. ANY ACCUMULATIONS...IF ANY...WOULD
NOT AMOUNT TO MORE THAN A FEW TENTHS. INTERESTINGLY...IF ANYTHING
DOES HAPPEN TO FALL IN THE FAR NORTH TONIGHT...IT MIGHT ACTUALLY
FAVOR THE FORM OF LIGHT SLEET BASED ON FORECAST SOUNDINGS...BUT
WILL LEAVE IT AS SNOW MENTION FOR NOW. HAVE ALSO BEEN GROWING A
BIT LEARY OF POSSIBLE LIGHT FREEZING DRIZZLE ACROSS NORTHERN
PORTIONS OF THE AREA GIVEN THE GOOD LOW LEVEL WARM ADVECTION...BUT
THINKING AT THIS POINT IS THAT ANY POTENTIAL STRATUS LAYER WOULD
BE TOO SHALLOW TO SUPPORT THIS. SOMETHING TO WATCH. AS FOR LOW
TEMPS...CHANGED THEM LITTLE...ALTHOUGH CONFIDENCE IN HOURLY TRENDS
IS QUITE LOW AS TEMPS COULD EASILY DISPLAY STEADY/SLOWLY RISING
CHARACTERISTICS AS BREEZES TURN SOUTHERLY. KEPT IT SIMPLE FOR NOW
THOUGH...INDICATING MOST AREAS BOTTOMING OUT BETWEEN 9 AND 15
DEGREES...ALTHOUGH THIS MIGHT END UP BEING EARLIER IN THE NIGHT
VERSUS LATER FOR SOME PLACES.
FRIDAY...THE MAIN BATCH OF SHORTWAVE ENERGY PASSES THROUGH THE
CENTRAL PLAINS...ALTHOUGH THE UPPER JET FORCING CONTINUES TO
DIRECT THE MAIN PRECIP EVENT FROM EASTERN SD INTO NORTHERN
IA/SOUTHERN MN AND POINTS EAST. THUS LEFT PRECIP MENTION OUT OF
THE FORECAST...ALTHOUGH ONCE AGAIN WILL HAVE TO MONITOR DEPTH OF
POSSIBLE STRATUS LAYER CLOSELY FOR OUTSIDE CHANCE OF SNEAKY LIGHT
FREEZING DRIZZLE THREAT...BUT JUST SEEMS RATHER UNLIKELY AT THIS
JUNCTURE. AS FOR HIGH TEMPS...THE SOUTHERN EDGE OF THE ARCTIC COLD
FRONT WILL PLAY A BIG ROLE AS IT IS PROGGED TO DROP RIGHT BACK
SOUTH ACROSS THE CWA OVER THE COURSE OF THE DAY...ALTHOUGH THE GFS
IS MUCH MORE AGGRESSIVE THAN THE LATEST ECMWF/NAM REGARDING WITH
THIS COLD PUSH. CONSENSUS OF SEVERAL MODELS/GUIDANCE WAS TO...YOU
GUESSED IT...LOWER TEMPS SEVERAL DEGREES...AND BUMPED DOWN 3-5
DEGREES MOST AREAS...NOW ADVERTISING MID 20S NORTHEAST TO UPPER
30S SOUTHWEST. INTERESTING TO NOTE THAT THIS DAY HAS NOW TRENDED
15+ DEGREES COLDER THAN FORECASTS ISSUED JUST 2-3 DAYS AGO.
FRIDAY NIGHT...IT REMAINS DRY AS A SURFACE RIDGE AXIS SLIDES
ACROSS THE CENTRAL PLAINS...AND A BRIEF BIT OF SHORTWAVE RIDGING
SETS IN ALOFT. ASSUMING LIMITED CLOUD COVER...TEMPS COULD TAKE A
DECENT TUMBLE...AND LOWERED LOWS 5 DEGREES MOST AREAS WITH SINGLE
DIGITS ABOVE ZERO NOW IN PLACE FOR MUCH OF THE CWA.
SATURDAY...THE NEXT...MORE VIGOROUS MID LEVEL WAVE STARTS MAKING
ITS WAY ACROSS THE CENTRAL/SOUTHERN ROCKIES...INDUCING SURFACE
PRESSURE FALLS AND RAMPING UP SOUTH-SOUTHEAST BREEZES INTO AT
LEAST THE 15-20 MPH SUSTAINED RANGE. DESPITE THIS SOUTHERLY
WIND...THE DIRECTION IS NOT OVERLY CONDUCIVE FOR SIGNIFICANT
WARMING...AND HAVE ONLY INDICATED A MODEST WARM-UP OVER
FRIDAY...WITH HIGHS RANGING FROM LOW 30S FAR EAST TO LOW 40S FAR
WEST.
SATURDAY NIGHT...LEFT THIS PERIOD DRY...AT LEAST FOR NOW...AS THE
INCOMING SHORTWAVE CONTINUES TO AMPLIFY/STRENGTHEN AS A 100+KT
UPPER JET STARTS TO ROUND THE BASE INTO THE CENTRAL PLAINS. ONLY
THING KEEPING POPS FROM BEING INSERTED AT THIS POINT IS SUGGESTION
THAT A MID LEVEL DRY SLOT WILL BE IN PLACE ACROSS THE CWA...WITH
MAIN FORCING/MID LEVEL DEFORMATION AXIS HOLDING JUST OFF TO THE
NORTH/WEST...THUS HOLDING OFF BETTER PRECIP CHANCES UNTIL SUNDAY
AS DISCUSSED BELOW.
LONG TERM...SUNDAY THROUGH WEDNESDAY. PATTERN REMAINS
PROGRESSIVE THROUGH THE EXTENDED PERIODS WITH CHALLENGE OF TRYING
TO TIME WAVES. BEGINNING ON SUNDAY...A 100+KT JET NOSES EAST FM
THE FOUR CORNERS REGION AND LIFTS NORTHEAST ACROSS THE CENTRAL
PLAINS DEEPENING THE MID/UPPER TROUGH ACROSS THE CENTRAL PLAINS.
THE 00Z ECMWF IS THE STRONGEST/SLOWEST WITH THE SYSTEM ON SUNDAY
AND CLOSES OFF THE H7 LOW...WHEREAS OTHER EXTENDED MODELS SUGGEST
A MORE PROGRESSIVE OPEN WAVE. IN GENERAL...THERE IS CONSENSUS
AMONG MODELS THAT OUR REGION WILL BE UNDER THE INFLUENCE OF A
TROUGH THRU AT LEAST THE FIRST HALF OF THE DAY...OR LONGER IF
SLOWER ECWMF VERIFIES. COOL FRONTAL BOUNDARY WILL SWEEP ACROSS OUR
REGION IN MORNING WITH AN AREA OF LOW CLOUDS/PCPN ACCOMPANYING
SYSTEM AIDED BY ENHANCED UPPER DYNAMICS IN LFQ OF JET. HOW LONG
PCPN/LOW CLOUDS LINGERS IS DEPENDENT ON STRENGTH OF SYSTEM AND IF
SYSTEM MOVES THRU FASTER...CLEARING SKIES/DOWNSLOPE CONDITIONS MAY
AID IN SOME WARMING FOR THE AFTN. IN ADDITION TO THE PCPN
POTENTIAL...MODELS ALSO SUGGEST STRONG WIND POTENTIAL SUNDAY WITH
NAM INDICATING 3HR PRESSURE RISES OF 6MB BEHIND THE FRONT IN
TIGHTENING SFC GRADIENT...WHILE A CORRIDOR OF 50 TO 60KT MID
LEVEL WINDS CROSS OUR REGION. WILL NEED TO MONITOR MODEL TRENDS OF
THIS AS WELL. FOR PCPN TYPE ON SUNDAY...HAVE WENT WITH R/S IN THE
MORNING TRANSITIONING TO RAIN IN AFTN AS TEMPS LOOK TO RISE ABOVE
FREEZING.
HEADING INTO SUNDAY NIGHT...THE TROUGH AXIS DEPARTS AND CONDITIONS
DRY WITH RISING HEIGHTS BEHIND THE EXITING SYSTEM. MODELS ARE STILL
LOOKING DRY MONDAY IN BETWEEN SYSTEMS...AND THEN NEXT WAVE IS PROGGED
TO EMERGE ONTO THE PLAINS ON TUESDAY. THERE IS STILL SOME
UNCERTAINTY ON DEGREE OF MOISTURE WITH THIS NEXT SYSTEM BUT SMALL
CHCS FOR PCPN STILL WARRANTED AS CURRENTLY FORECAST. MILD AIRMASS IN PLACE
SHLD MAINTAIN LIQUID CHCS INITIALLY WITH POTENTIAL FOR CHANGE TO
SNOW IN COOLER AIR WITH FROPA TUESDAY NIGHT.
THE AIRMASS IN GENERAL DURING THE EXTENDED IS NOT OVERLY COLD AND
TEMPS LOOK TO BE MORE DEPENDENT ON CLOUDS/PCPN.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE/SHORT TERM...PFANNKUCH
LONG TERM/AVIATION...CF
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
932 AM EST THU JAN 19 2012
.SYNOPSIS...
MUCH OF TODAY WILL FEATURE DRY WEATHER...AND SEASONABLY CHILLY
TEMPERATURES. A COLD FRONT WILL CROSS THE AREA THIS EVENING...ACCOMPANIED
BY SNOW SHOWERS...AND A FEW SQUALLS. BEHIND THE FRONT...A BRIEF
PERIOD OF LAKE EFFECT SNOW SHOULD IMPACT UPSTATE NEW YORK LATE
TONIGHT AND EARLY FRIDAY...BEFORE DIMINISHING IN THE AFTERNOON. A
FAST MOVING STORM SYSTEM SHOULD TRACK INTO THE MID-ATLANTIC STATES
BY SATURDAY...PERHAPS BRINGING A PERIOD OF SNOW OR MIXED
PRECIPITATION TO START THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
930 AM UPDATE...LATEST HRRR REFLECTIVITY SUGGESTS IF THERE IS A
SQUALL, IT WILL ARRIVE WELL AFTER SUNSET. WE WILL CONTINUE TO
WATCH THE MESOSCALE MODEL TRENDS AND THE OBS/SAT FOR CLUES AS TO
TIMING AND INTENSITY OF SNOW SHOWERS.
CURRENT GRIDS HAVE BEEN TWEAKED FOR TEMPS. OTHERWISE THE FORECAST
LOOKS TO BE IN GOOD SHAPE.
7 AM UPDATE... JUST MINOR TWEAKS TO TEMP/SKY GRIDS.
INITIAL BAND OF HIGH-LVL CLDS IS ERODING ATTM...SO WE ADJUSTED TO
GO FOR A SUNNIER AM PD...BEFORE THICKER CLDS COME IN FROM THE W
TWDS MIDDAY.
OTHWS...NO SIG CHANGES.
PREV DISC... 5 AM UPDATE...ALL IS QUIET EARLY THIS MRNG...AND
SHOULD REMAIN SO FOR MUCH OF THE DAY...WITH JUST AN INCREASE IN
MAINLY MID AND HIGH-LVL CLDS FROM MIDDAY ON. TEMPS SHOULD REBOUND
INTO THE UPPER 20S OR LOWER 30S FOR MANY LOCALES THIS AFTN...WITH
A FAIRLY ROBUST SRLY FLOW DVLPG (HILLTOP SXNS GUSTING TO NEAR 30
MPH AFTER 18Z).
A SHARP COLD FRNT WAS CROSSING CNTRL MI AND THE CHICAGO AREA JUST
PRIOR TO SUNRISE. THE FRNT WAS MAKING STEADY EWD PROGRESS...AND
ALL NEAR-TERM GUIDANCE IS IN AGREEMENT THAT THIS SYSTEM WILL STRETCH
ACRS WRN NY BY 21Z. AS MOIST AND FORCING BEGIN TO INCREASE IN
ADVANCE OF THIS SYSTEM...SCTD SHSN AND FLRYS SHOULD DEVELOP IN OUR
NRN/WRN ZNS BY LATE IN THE DAY...SPCLY THE SRN TUG HILL
RGN...WHERE SRLY UPSLOPE FLOW WILL BE WELL ESTABLISHED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
530 AM UPDATE... THE ABV MENTIONED COLD FRNT WILL CROSS THE FA
THIS EVE...GENERALLY IN THE 00-04Z TIME FRAME...LIKELY ACCOMPANIED
BY A FEW SQUALLS...SPCLY N AND W OF KBGM. ALTHOUGH LOW-LVL LR`S
SEEM TO BE A BIT SHORT OF WHAT WE`D NORMALLY SEE IN A FRNTL
SQUALL/WINDEX SITN...THEY ARE STILL IN THE 7-8C/KM RANGE IN THE
LOWEST 3 KM AGL. THE SUPPORTING UPPER-LVL TROUGH IS ALSO FAIRLY
DYNAMIC IN NATURE...AND GOOD LOW-LVL CAA FOLLOWS BEHIND THE SFC
FRNT. THUS...WE FEEL SOME AREAS WILL SEE A QUICK INCH OR SO OF
ACCUM THIS EVE...MOSTLY CNY.
AFTER A 3-5 HOUR PERIOD OF MOSTLY DRY WX...OR PERHAPS A FEW FLRYS/-SHSN...
FOR THE LATE EVE/OVERNIGHT TIME FRAME...THE LES MACHINE SHOULD
KICK INTO GEAR E AND SE OF LK ONT IN THE PRE-DAWN HRS (06-09Z).
NWP AGREEMENT (NAM12/LOCAL WRF/GFS40) IS PRETTY GOOD THAT A SINGLE
BAND WILL FIRST IMPACT OSWEGO/LEWIS CNTYS...BEFORE DROPPING INTO
NRN ONEIDA BY 08-09Z. FOR A RELATIVELY SHORT PD EARLY FRI...A
MULTI-LK INFLUENCE WITH GEO BAY LOOKS PSBL...WHICH WOULD HELP TO
ENHANCE MOIST DEPTHS/DZ FAVORABILITY. DUE TO THE COMBO OF 1-3"
EARLIER THU EVE WITH THE FRNT...AND THEN AN ADDITIONAL SEVERAL
INCHES OF LAKE EFF ACCUM EARLY FRI...A WINTER WX ADVSY HAS BEEN
POSTED FOR NRN ONEIDA.
PRESENT INDICATIONS ARE THAT THE MAIN LES BAND WILL GRADUALLY
WEAKEN AFTER 12Z FRI...AS IT DROPS SWD THROUGH
ONONDAGA/MADISON/SRN ONEIDA CNTYS...AND INTO
CORTLAND/CHENANGO/OTSEGO CNTYS. A LOWERING INVERSION...COMPROMISED
DENDRITE PRODUCTION...AND INCREASED DIR SHEAR...SHOULD ALL TAKE
THEIR TOLL...LIKELY CAUSING ACCUMS TO DROP OFF WITH TIME. OUR SRN
ZNS SHOULD ONLY SEE A FEW FLRYS AT WORST...WITH PROBABLE BREAKS OF
SUNSHINE BY AFTN.
AFTER A BRIEF LULL EARLY FRI EVE...THE NEXT SYNOPTIC SYSTEM IS
SLATED TO QUICKLY ARRIVE. MODEL EVOLUTION IS ALL PRETTY SIMILAR AT
THIS PT...TAKING A FAST MOVING SFC WAVE FROM THE OH/TN VLYS LATE
FRI NGT...TO THE DELMARVA RGN ON SAT. ALTHOUGH A STG WAA PATN
BECOMES ESTABLISHED THIS PD ACRS NE PA/CNY...ALG WITH A DEEPENING
MOIST SUPPLY...THE MAIN UPPER-LVL WAVE IS RATHER FLAT AND FAST
MOVG...AND THIS RAPID SYSTEM MOVEMENT COULD WELL KEEP PCPN AMTS
DOWN. MY GUT FEELING IS THAT MODEL QPF`S OF 0.3-0.5" LIQUID ARE A
BIT OVERDONE...BUT EVEN IF THEY ARE...SEVERAL INCHES OF SNOW ARE
STILL PSBL. WE`LL ALSO HAVE TO WATCH FOR THE PSBLTY THAT AN
ELEVATED WARM LYR BECOMES INCORPORATED...WHICH COULD POTENTIALLY
CREATE A WINTRY MIX SITN FOR PTNS OF THE FA. WE`LL BE MONITORING
THIS SYSTEM CLOSELY OVER THE NEXT COUPLE OF DAYS.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
PATTERN OF A GENERAL SOUTHWEST FLOW WITH OCCASIONAL WAVES...WILL
ALTERNATE US ON EITHER SIDE OF THE 540 DECAMETER LINE IN REGARDS
TO 1000-500MB THICKNESS. REGARDLESS OF PRECIPITATION TYPE DURING
THE PERIOD...IT WILL BE A WARMER THAN NORMAL PATTERN FOR LATE
JANUARY...A THEME THAT HAS DOMINATED MOST OF THIS WINTER SO FAR.
WE BEGIN SATURDAY NIGHT THROUGH SUNDAY MORNING...BETWEEN WAVES
WITH SEASONABLY COLD LOWS AND MAINLY DRY WEATHER. AN EXTENSION OF
A SOUTHERN STREAM UPPER WAVE MAY SKIM US LATE SUNDAY INTO MONDAY
MORNING. IF PRECIPITATION MANAGES TO REACH US...GENERAL SET UP AND
GFS MODEL SOUNDINGS SUGGEST THERE IS SOME PROSPECT FOR A LIGHT
WINTRY MIX INITIALLY BEFORE PLAIN RAIN. GFS/ECWMF AGREE BETTER
THOUGH...ON A NORTHERN STREAM TROUGH THEN SWINGING THROUGH LATE
MONDAY OR MONDAY NIGHT. THE COLD AIR BEHIND THAT SYSTEM LOOKS
PRETTY MEAGER...SO UNLESS BETTER PENETRATION OF COLDER AIR
OCCURS...THE RESULTING LAKE RESPONSE ON TUESDAY ALSO LOOKS
MEDIOCRE. WE MAY END UP JUST HAVING SCATTERED SNOW SHOWERS SIMPLY
FROM SYNOPTIC WRAP AROUND/COMMA HEAD OF SYSTEM...WITH NOT A WHOLE
LOT OF ASSISTANCE FROM THE LAKES. THE DOMINANT SOUTHWEST FLOW
QUICKLY BRINGS IN WARMER AIR AND SURFACE HIGH PRESSURE INTO
WEDNESDAY...AND TEMPERATURES LOOK TO BE ROUGHLY 10 DEGREES ABOVE
NORMAL AT THAT TIME. NORTH ATLANTIC OSCILLATION INDEX IS POSITIVE
NOW...AND IS FORECAST TO REMAIN POSITIVE THIS WEEK...SUPPORTING
THE WARMER THAN NORMAL PATTERN.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
HIGH PRESSURE WILL WEAKEN TODAY AS A LOW PRESSURE SYSTEM
APPROACHES THE REGION FROM THE WEST. HIGH CLOUDS WILL MOVE IN
LATER THIS MORNING. VFR CONDITIONS WILL LAST UNDER A HIGH TO MID
DECK OF CLOUDS UNTIL THE VERY LATE AFTERNOON OR EARLY EVENING.
THEN CIGS WILL DROP TO MVFR AND LIGHT SNOW SHOWERS WILL BEGIN TO
MOVE IN. A COLD FRONT WILL THEN CROSS THE AREA TONIGHT, AROUND
MIDNIGHT. A AREA OF HEAVIER SNOW IS EXPECTED ALONG WITH THE FRONT,
WHICH MAY BRING A PERIOD OF IFR CIGS AND VSBYS TO MOST TAF SITES,
ESPECIALLY FURTHER NORTH, SUCH AS SYR AND RME. CONDITIONS SHOULD
BEGIN TO IMPROVE IN THE PREDAWN HOURS TOMORROW MORNING BEHIND THE
FRONT, WITH THE EXCEPTION OF RME AND SYR, WHERE LAKE EFFECT SNOW
IS EXPECTED TO DEVELOP ONCE AGAIN.
WINDS WILL PICK UP OUT OF THE SOUTH THIS MORNING BETWEEN 5 AND 10
KTS. AS THE PRESSURE GRADIENT INCREASES, WITH THE LOW APPROACHING,
WINDS WILL INCREASE TO AROUND 15KTS WITH GUSTS TO AROUND 25 KTS.
THE GUSTS WILL LAST UNTIL THE FRONTAL PASSAGE AND WILL AFFECT
VSBYS WITH BLSN. BEHIND THE FRONT, WINDS WILL TURN WNW BETWEEN 5
AND 10 KTS.
.OUTLOOK...
LATE THURSDAY TO FRIDAY...MVFR. LIGHT SNOW CHANGING TO LAKE
EFFECT SNOW IN NY BY FRIDAY.
SATURDAY...MVFR IN SNOW SHOWERS.
SUNDAY...MAINLY VFR.
MONDAY..MVFR POSSIBLE IN RAIN OR SNOW.
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 9 AM EST
FRIDAY FOR NYZ009.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...DJP/MLJ
SHORT TERM...MLJ
LONG TERM...MDP
AVIATION...SLI
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1225 PM MST THU JAN 19 2012
.UPDATE...
&&
.SHORT TERM...ALL HILITES HAVE EITHER BEEN CANCELLED OR EXPIRED.
WILL STILL BE LOOKING AT POSSIBLE HIGH WINDS AGAIN IN THE
FOOTHILLS TONIGHT BUT MAY END UP BEING MORE LOCALIZED. MOISTURE
DEPTH IN THE MOUNTAINS OVER NEXT 24 HOURS LOOKS RATHER SHALLOW SO
WILL LEAN TOWARDS NO HILITES WITH JUST LIGHTER SNOW AMOUNTS. GIVEN
THE INCREASING WINDS OVER THE PASSES MAY STILL NEED AN ADVISORY.
STAY TUNED FOR AFTERNOON UPDATES.
.AVIATION...NO CHANGES PER 18Z TAF WITH AN EASTERLY COMPONENT OF
THE WINDS AT ALL LOCAL TERMINALS. BJC COULD SHOW MORE WESTERLY
TONIGHT AS NEXT MOUNTAIN WAVE DECENDS THE HILL.
&&
.PREV DISCUSSION... /ISSUED 1006 AM MST THU JAN 19 2012/
UPDATE...
SHORT TERM...HAVE ALREADY CANCELLED THE BLIZZARD WARNING FOR THE
MOUNTAINS PER OBSERVATIONS AND WEB CAMS. STILL SOME LIGHT SNOW AND
GUSTY WINDS BUT CERTAINLY NOTHING WIDESPREAD. ALSO CANCELLED THE
HIGH WIND WARNING FOR ZONES 38 AND 39 AS MOUNTAIN WAVE HAS MOVED
BACK UP THE HILL AND SURFACE GRADIENT HAS RELAXED. WIND GUSTS
GENERALLY UNDER 50 MPH. THERE IS SOME MORE POTENTIAL FOR HIGH
WINDS AGAIN TONIGHT IN THE FOOTHILLS AND WILL LOOK AT SOME MORE
DATA BEFORE MAKING A DECISION. WILL MOVE LIKELY LET THE REMAINDER
OF THE HIGH WIND WARNING EXPIRE AT NOON. THE ZONE 31 WINTER STORM
WARNING DOESN`T LOOK GOOD AT THE MOMENT WITH VERY LITTLE SNOW
ONGOING BUT THIS SHOULD CHANGE LATER TODAY AND TONIGHT. HAVE
WORDED THE WSW ACCORDINGLY WITHOUT ACTUALLY CANCELLING IT.
AVIATION...SURFACE WINDS AT LOCAL TERMINALS GENERALLY SOUTHEAST
AND WILL PLAY THE PERSISTENCE FOR MUCH OF THE DAY. BJC MAY SEE
SOME WESTERLIES TONIGHT BUT A LITTLE SURPRISED THEY DIDN`T BLOW
MUCH LAST NIGHT.
PREV DISCUSSION... /ISSUED 352 AM MST THU JAN 19 2012/
SHORT TERM...A STRONG NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER
THE CWFA TODAY AND TONIGHT. STRONG WINDS HAVE NOT BEEN AS
WIDESPREAD THIS MORNING AS THE MDLS HAD SUGGESTED. THE STRONGEST
WINDS APPEARED TO HAVE OCCUR PRIOR TO MIDNIGHT. ALTHOUGH THE JET
MAX HAS SHIFTED TO THE NORTH AND EAST...THE SHEAR APPEARS TO HAVE
LESSENED THE IMPACT OF THE MOUNTAIN WAVE SO FAR THIS MORNING. IF
WE GET ANY MORE STRONG WINDS IT WILL LIKELY OCCUR PRIOR TO 15Z
THIS MORNING. IF IT DOES NOT MATERIALIZE BY THAT TIME...THEN THE DAY
SHIFT CAN CANCEL THE HIGH WIND WARNING. THE SAME CAN BE SAID FOR
THE BLIZZARD WARNING. LGT SNOW HAS DEVELOPED IN THE MOUNTAINS
OVERNIGHT AND STRONG WINDS APPEAR TO BE IMPACTING TRAVEL NEAR THE
EISENHOWER TUNNEL. THE BLIZZARD CONDITIONS WILL BE MORE WIDESPREAD
ABOVE TIMBERLINE. THOSE WINDS ARE STILL EXPECTED TO DECREASE IN
MAGNITUDE BY THIS AFTERNOON. ADDITIONAL HIGHLIGHTS MAY BE
NECESSARY FOR ZONE 33 AND 34 THIS AFTN AND TNGT. WILL LET THE
CURRENT HIGHLIGHT RUN ITS COURSE. NOT SURE THE SNOW WILL BE ENUF
TO WARRANT A WINTER STORM WARNING VS A WINTER WEATHER ADVISORY
FOR SNOW AND BLOWING SNOW. THE MDLS APPEAR TO HIT THE MOUNTAINS
NORTH OF INTERSTATE 70 THE HARDEST. THE WINTER STORM WARNING FOR
ZONE 31 STILL LOOKS ON TRACK AND ZONE 33 WILL GET SOME DECENT
SNOWFALL AS WELL. THE BEST POTENTIAL FOR SNOW WILL BE TONIGHT AS
THE MOISTURE WEST OF THE CONTINENTAL DIVIDE DEEPENS AND THE MID
LEVEL LAPSE RATES IMPROVE. NAM12 SPATIAL CROSS-SECTIONS KEEP AN
80 KTS CROSS- MOUNTAIN COMPONENT OF 80 KTS AROUND 600 MB LATE THIS
AFTN AND TONIGHT. THE WAVE AMPLICATION OVERNIGHT APPEARS FAIRLY
LIMITED SO DO NOT ANTICIPATE HIGH WINDS IN THE FOOTHILLS AS MUCH
TONIGHT. AS FOR THE NORTHEAST PLAINS...IT WILL BE DRY WITH
TEMPERATURES IN THE MID 50S TO LOWER 60S... MILDEST NEAR THE
FOOTHILLS. OVERALL ONLY MINOR ADJUSTMENTS IN THE SHORT TERM.
LONG TERM...STRONG WESTERLY FLOW ALOFT WILL CONTINUE TO TRANSPORT
PACIFIC MOISTURE ACROSS THE WESTERN U.S. THROUGH THE WEEKEND. THE
NEXT WRINKLE IN THE FLOW ALOFT WILL MOVE ACROSS THE STATE TONIGHT
AND FRIDAY. THE MOISTURE EMBEDDED IN THE STRONG WESTERLY FLOW ALOFT
WILL PRODUCE A ROUND OF OROGRAPHIC SNOW. LAPSE RATES WILL BE AROUND
5-6 C/KM...NOT THAT GREAT BUT NOT BAD EITHER. BEST SNOW ON FRIDAY
WILL OCCUR OVER WESTERN JACKSON COUNTY WHERE LOCALLY A FOOT OF NEW
SNOW IS POSSIBLE. LESSER AMOUNTS ARE EXPECTED TO THE SOUTH OVER THE
MOUNTAINS OF GRAND AND JACKSON COUNTIES. THIS SYSTEM IS PRIMARILY AN
OROGRAPHIC SNOW PRODUCER. THE MOUNTAIN VALLEYS WILL SEE A FEW STRAY
SNOW SHOWERS OFF THE MOUNTAINS. FOR THE FRONT RANGE AND EASTERN
PLAINS...DRY AND MILD CONDITIONS WILL PREVAIL.
WILL SEE A BREAK IN THE SNOW FRIDAY NIGHT AND SATURDAY. SLIGHT
RIDGING WILL OCCUR DUE TO THE NEXT SHORT WAVE TROUGH NEARING THE
ROCKIES. THIS NEXT SYSTEM WILL MOVE ACROSS THE STATE SATURDAY
NIGHT...WITH SNOW STARTING OVER NORTH CENTRAL COLORADO LATE SATURDAY
AFTERNOON. THIS WAVE IS STRONGER THAN THURSDAY NIGHT/FRIDAY`S
SYSTEM. IN ADDITION...LAPSE RATES WILL BE 7-8 C/KM SATURDAY NIGHT.
ALL OF THIS WILL PRODUCE A PERIOD OF MODERATE TO HEAVY OROGRAPHIC
SATURDAY NIGHT. WILL LIKELY NEED WINTER WEATHER HIGHLIGHTS AS THIS
SYSTEM NEARS. WOULD EXPECT THE FAVORED OROGRAPHIC SLOPES TO PICK UP
1-2 FEET OF SNOW. MOST OF THE SNOW WILL AGAIN BE OROGRAPHICALLY
DRIVEN. THERE WILL BE A BETTER CHANCE FOR SNOW IN THE MOUNTAINS
VALLEYS DUE TO BETTER INSTABILITY. WILL NOT RULE OUT THE CHANCE OF A
FEW LIGHT SNOW SHOWERS OVER THE PLAINS EITHER. ANY PRECIPITATION
HERE WILL BE LIGHT. AFTER A MILD SATURDAY OVER NORTHEAST COLORADO
WHERE HIGHS WILL BE IN THE 50S...COOLER AIR WILL MOVE IN BEHIND THE
SYSTEM FOR SUNDAY WITH HIGHS IN THE 40S.
PROGRESSIVE WEATHER PATTER WILL CONTINUE THROUGH THE EARLY PART OF
NEXT WEEK. RIDGING ON MONDAY WILL BE FOLLOWED BY A TROUGH ON
TUESDAY. THEN ANOTHER RIDGE TO AFFECT THE AREA LATE WEDNESDAY AND
INTO THURSDAY. WILL KEEP POPS IN THE MOUNTAINS EACH DAY DUE TO THE
SOMEWHAT MOIST WESTERLY FLOW AND ALSO DUE TO TIMING UNCERTAINTIES
WITH THESE SYSTEMS. THE ENERGY WITH THE SYSTEM ON TUESDAY LOOKS LIKE
IT WILL SPLIT AND MOVE AROUND COLORADO. THIS WILL KEEP MOUNTAIN
SNOWFALL AMOUNTS ON THE LIGHTER SIDE. FOR THE PLAINS...OTHER THAN
LOW POPS FOR THE SYSTEM MONDAY NIGHT TUESDAY WILL KEEP THE FORECAST
DRY. HIGHS WILL BE NEAR NORMAL AFTER THE TROUGH PASSAGE
TUESDAY...OTHERWISE ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR
NORTHEAST COLORADO.
AVIATION...WIND WILL CONTINUE TO BE AN ISSUE...ESPECIALLY AT KBJC
AND KDEN THIS MORNING. AT KDEN WILL CONTINUE WITH A WESTERLY WIND
THIS MORNING UNTIL AROUND 15Z THEN IT APPEAR TO WEAKEN AND BECOME
MORE SWLY. NONE OF THE MDLS HAVE HANDLED THE WIND PATTERN VERY
WELL THIS MORNING. I WILL BE FOLLOWING THE RUC BOUNDARY LAYER
WINDS THIS MORNING. IF THE SFC TROUGH SITS ALONG THE FRONT RANGE
THIS AFTN...THEN SOME SORT OF ELY WIND COMPONENT IS STILL
POSSIBLE. AS FOR KBJC...WINDS HAVE BEEN SLOW TO MATERIALIZE THIS
MORNING. WILL KEEP THE STRONGER GUSTS IN THE TAF UNTIL 15Z THEN
DECREASE IT THEREAFTER.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...NONE
&&
$$
SHORT TERM...ENTREKIN
LONG TERM....KRIEDERMAN
AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1006 AM MST THU JAN 19 2012
.UPDATE...
&&
.SHORT TERM...HAVE ALREADY CANCELLED THE BLIZZARD WARNING FOR THE
MOUNTAINS PER OBSERVATIONS AND WEB CAMS. STILL SOME LIGHT SNOW AND
GUSTY WINDS BUT CERTAINLY NOTHING WIDESPREAD. ALSO CANCELLED THE
HIGH WIND WARNING FOR ZONES 38 AND 39 AS MOUNTAIN WAVE HAS MOVED
BACK UP THE HILL AND SURFACE GRADIENT HAS RELAXED. WIND GUSTS
GENERALLY UNDER 50 MPH. THERE IS SOME MORE POTENTIAL FOR HIGH
WINDS AGAIN TONIGHT IN THE FOOTHILLS AND WILL LOOK AT SOME MORE
DATA BEFORE MAKING A DECISION. WILL MOVE LIKELY LET THE REMAINDER
OF THE HIGH WIND WARNING EXPIRE AT NOON. THE ZONE 31 WINTER STORM
WARNING DOESN`T LOOK GOOD AT THE MOMENT WITH VERY LITTLE SNOW
ONGOING BUT THIS SHOULD CHANGE LATER TODAY AND TONIGHT. HAVE
WORDED THE WSW ACCORDINGLY WITHOUT ACTUALLY CANCELLING IT.
.AVIATION...SURFACE WINDS AT LOCAL TERMINALS GENERALLY SOUTHEAST
AND WILL PLAY THE PERSISTENCE FOR MUCH OF THE DAY. BJC MAY SEE
SOME WESTERLIES TONIGHT BUT A LITTLE SURPRISED THEY DIDN`T BLOW
MUCH LAST NIGHT.
&&
.PREV DISCUSSION... /ISSUED 352 AM MST THU JAN 19 2012/
SHORT TERM...A STRONG NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER
THE CWFA TODAY AND TONIGHT. STRONG WINDS HAVE NOT BEEN AS
WIDESPREAD THIS MORNING AS THE MDLS HAD SUGGESTED. THE STRONGEST
WINDS APPEARED TO HAVE OCCUR PRIOR TO MIDNIGHT. ALTHOUGH THE JET
MAX HAS SHIFTED TO THE NORTH AND EAST...THE SHEAR APPEARS TO HAVE
LESSENED THE IMPACT OF THE MOUNTAIN WAVE SO FAR THIS MORNING. IF
WE GET ANY MORE STRONG WINDS IT WILL LIKELY OCCUR PRIOR TO 15Z
THIS MORNING. IF IT DOES NOT MATERIALIZE BY THAT TIME...THEN THE DAY
SHIFT CAN CANCEL THE HIGH WIND WARNING. THE SAME CAN BE SAID FOR
THE BLIZZARD WARNING. LGT SNOW HAS DEVELOPED IN THE MOUNTAINS
OVERNIGHT AND STRONG WINDS APPEAR TO BE IMPACTING TRAVEL NEAR THE
EISENHOWER TUNNEL. THE BLIZZARD CONDITIONS WILL BE MORE WIDESPREAD
ABOVE TIMBERLINE. THOSE WINDS ARE STILL EXPECTED TO DECREASE IN
MAGNITUDE BY THIS AFTERNOON. ADDITIONAL HIGHLIGHTS MAY BE
NECESSARY FOR ZONE 33 AND 34 THIS AFTN AND TNGT. WILL LET THE
CURRENT HIGHLIGHT RUN ITS COURSE. NOT SURE THE SNOW WILL BE ENUF
TO WARRANT A WINTER STORM WARNING VS A WINTER WEATHER ADVISORY
FOR SNOW AND BLOWING SNOW. THE MDLS APPEAR TO HIT THE MOUNTAINS
NORTH OF INTERSTATE 70 THE HARDEST. THE WINTER STORM WARNING FOR
ZONE 31 STILL LOOKS ON TRACK AND ZONE 33 WILL GET SOME DECENT
SNOWFALL AS WELL. THE BEST POTENTIAL FOR SNOW WILL BE TONIGHT AS
THE MOISTURE WEST OF THE CONTINENTAL DIVIDE DEEPENS AND THE MID
LEVEL LAPSE RATES IMPROVE. NAM12 SPATIAL CROSS-SECTIONS KEEP AN
80 KTS CROSS- MOUNTAIN COMPONENT OF 80 KTS AROUND 600 MB LATE THIS
AFTN AND TONIGHT. THE WAVE AMPLICATION OVERNIGHT APPEARS FAIRLY
LIMITED SO DO NOT ANTICIPATE HIGH WINDS IN THE FOOTHILLS AS MUCH
TONIGHT. AS FOR THE NORTHEAST PLAINS...IT WILL BE DRY WITH
TEMPERATURES IN THE MID 50S TO LOWER 60S... MILDEST NEAR THE
FOOTHILLS. OVERALL ONLY MINOR ADJUSTMENTS IN THE SHORT TERM.
LONG TERM...STRONG WESTERLY FLOW ALOFT WILL CONTINUE TO TRANSPORT
PACIFIC MOISTURE ACROSS THE WESTERN U.S. THROUGH THE WEEKEND. THE
NEXT WRINKLE IN THE FLOW ALOFT WILL MOVE ACROSS THE STATE TONIGHT
AND FRIDAY. THE MOISTURE EMBEDDED IN THE STRONG WESTERLY FLOW ALOFT
WILL PRODUCE A ROUND OF OROGRAPHIC SNOW. LAPSE RATES WILL BE AROUND
5-6 C/KM...NOT THAT GREAT BUT NOT BAD EITHER. BEST SNOW ON FRIDAY
WILL OCCUR OVER WESTERN JACKSON COUNTY WHERE LOCALLY A FOOT OF NEW
SNOW IS POSSIBLE. LESSER AMOUNTS ARE EXPECTED TO THE SOUTH OVER THE
MOUNTAINS OF GRAND AND JACKSON COUNTIES. THIS SYSTEM IS PRIMARILY AN
OROGRAPHIC SNOW PRODUCER. THE MOUNTAIN VALLEYS WILL SEE A FEW STRAY
SNOW SHOWERS OFF THE MOUNTAINS. FOR THE FRONT RANGE AND EASTERN
PLAINS...DRY AND MILD CONDITIONS WILL PREVAIL.
WILL SEE A BREAK IN THE SNOW FRIDAY NIGHT AND SATURDAY. SLIGHT
RIDGING WILL OCCUR DUE TO THE NEXT SHORT WAVE TROUGH NEARING THE
ROCKIES. THIS NEXT SYSTEM WILL MOVE ACROSS THE STATE SATURDAY
NIGHT...WITH SNOW STARTING OVER NORTH CENTRAL COLORADO LATE SATURDAY
AFTERNOON. THIS WAVE IS STRONGER THAN THURSDAY NIGHT/FRIDAY`S
SYSTEM. IN ADDITION...LAPSE RATES WILL BE 7-8 C/KM SATURDAY NIGHT.
ALL OF THIS WILL PRODUCE A PERIOD OF MODERATE TO HEAVY OROGRAPHIC
SATURDAY NIGHT. WILL LIKELY NEED WINTER WEATHER HIGHLIGHTS AS THIS
SYSTEM NEARS. WOULD EXPECT THE FAVORED OROGRAPHIC SLOPES TO PICK UP
1-2 FEET OF SNOW. MOST OF THE SNOW WILL AGAIN BE OROGRAPHICALLY
DRIVEN. THERE WILL BE A BETTER CHANCE FOR SNOW IN THE MOUNTAINS
VALLEYS DUE TO BETTER INSTABILITY. WILL NOT RULE OUT THE CHANCE OF A
FEW LIGHT SNOW SHOWERS OVER THE PLAINS EITHER. ANY PRECIPITATION
HERE WILL BE LIGHT. AFTER A MILD SATURDAY OVER NORTHEAST COLORADO
WHERE HIGHS WILL BE IN THE 50S...COOLER AIR WILL MOVE IN BEHIND THE
SYSTEM FOR SUNDAY WITH HIGHS IN THE 40S.
PROGRESSIVE WEATHER PATTER WILL CONTINUE THROUGH THE EARLY PART OF
NEXT WEEK. RIDGING ON MONDAY WILL BE FOLLOWED BY A TROUGH ON
TUESDAY. THEN ANOTHER RIDGE TO AFFECT THE AREA LATE WEDNESDAY AND
INTO THURSDAY. WILL KEEP POPS IN THE MOUNTAINS EACH DAY DUE TO THE
SOMEWHAT MOIST WESTERLY FLOW AND ALSO DUE TO TIMING UNCERTAINTIES
WITH THESE SYSTEMS. THE ENERGY WITH THE SYSTEM ON TUESDAY LOOKS LIKE
IT WILL SPLIT AND MOVE AROUND COLORADO. THIS WILL KEEP MOUNTAIN
SNOWFALL AMOUNTS ON THE LIGHTER SIDE. FOR THE PLAINS...OTHER THAN
LOW POPS FOR THE SYSTEM MONDAY NIGHT TUESDAY WILL KEEP THE FORECAST
DRY. HIGHS WILL BE NEAR NORMAL AFTER THE TROUGH PASSAGE
TUESDAY...OTHERWISE ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR
NORTHEAST COLORADO.
AVIATION...WIND WILL CONTINUE TO BE AN ISSUE...ESPECIALLY AT KBJC
AND KDEN THIS MORNING. AT KDEN WILL CONTINUE WITH A WESTERLY WIND
THIS MORNING UNTIL AROUND 15Z THEN IT APPEAR TO WEAKEN AND BECOME
MORE SWLY. NONE OF THE MDLS HAVE HANDLED THE WIND PATTERN VERY
WELL THIS MORNING. I WILL BE FOLLOWING THE RUC BOUNDARY LAYER
WINDS THIS MORNING. IF THE SFC TROUGH SITS ALONG THE FRONT RANGE
THIS AFTN...THEN SOME SORT OF ELY WIND COMPONENT IS STILL
POSSIBLE. AS FOR KBJC...WINDS HAVE BEEN SLOW TO MATERIALIZE THIS
MORNING. WILL KEEP THE STRONGER GUSTS IN THE TAF UNTIL 15Z THEN
DECREASE IT THEREAFTER.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING UNTIL NOON MST TODAY FOR COZ035-036.
WINTER STORM WARNING UNTIL 5 PM MST FRIDAY FOR COZ031.
&&
$$
SHORT TERM...ENTREKIN
LONG TERM....KRIEDERMAN
AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS ALBANY NY
442 PM EST THU JAN 19 2012
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO LINGER OVER THE REGION INTO THE
AFTERNOON...THEN A FAST MOVING CLIPPER TYPE SYSTEM WILL IMPACT OUR
REGION LATE BY THIS EVENING...BRINGING SOME LIGHT SNOW AND SNOW
SHOWERS. A MORE SIGNIFICANT STORM MAY IMPACT OUR REGION LATE FRIDAY
NIGHT THROUGH SATURDAY AS IT MOVES FROM THE TENNESSEE VALLEY ACROSS
THE MIDDLE ATLANTIC REGION.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
AS OF 1230 PM...HAD TO BACK OFF THE ARRIVAL OF CLOUDS AND ANY SNOW
PER SURFACE OBS. RADARS INDICATED THE SNOW SHOWERS WERE JUST
ENTERING BUFFALO. THE HRRR EXPERIMENTAL MODEL DOES INDICATE RETURNS
OF NEAR 20 DBZ NOT REACHING ALBANY UNTIL 00Z. PREVIOUS PACKAGE HAD
IT ARRIVING A FEW HOURS. THE AIR IS VERY DRY(AS WAS OUR 12Z RAOB)
AND WILL LIKELY CAUSE THE INITIAL SURGE OF MOISTURE TO EVAPORATE.
NO CHANGE ON HIGH TEMPERATURES BASED ON THIS 12Z RAOB WHICH WHEN
FULLY MIXING THE LOW LEVEL INVERSION GAVE ALBANY A HIGH OF 26. WE
ARE ALREADY 23...SO UPPER 20S LOOKS HERE...LOWER 30S SOUTH AND 20-25
MOST OTHER PLACES...EXCEPT TEENS FAR NORTH AND HIGHEST ELEVATION.
ALL PRECIPITATION SHOULD BE SNOW WITH THIS SYSTEM...BUT FINAL
SNOWFALL AMOUNTS STILL NOT ETCHED IN STONE. FOR NOW...LEFT CURRENT
THINKING FROM TONIGHT ALONE AS WE CONTINUE TO ACCESS ON THE NEW
INCOMING DATA.
FOR THE NEXT SEVERAL HOURS...LOOK FOR SUNSHINE TO BE FOLLOWED BY
RAPID INCREASING CLOUDS FROM THE WEST AND ANY SNOW LIKELY TO HOLD
OFF CERTAINLY FROM THE HUDSON VALLEY EAST...POSSIBLY REACHING OUR
SOUTHERN ADIRONDACKS BY 400 PM.
********PREVIOUS NEAR TERM FORECAST**************
AS OF 950 AM EST...A CLIPPER LOW CONTINUES TO QUICKLY APPROACH
FROM SOUTHEASTERN ONTARIO THIS AFTERNOON. THE HIGH CLOUDS IN
ADVANCE OF A WEAK WARM FRONT CONTINUES TO OVERSPREAD THE REGION.
THE DENSER CANOPY OF CLOUDS IS OVER WRN NY. WE RETOOLED THE CLOUD
TRENDS AND THE POP/WX TRENDS BASED ON THE LATEST NAM/HRRR. THE
WARM ADVECTION LIGHT SNOW/SNOW SHOWERS DOESN/T LOOK LIKE IT WILL
MOVE INTO MOST OF THE REGION UNTIL AFTER 23Z /6 PM/. THE BEST
CHANCE OF SOME SNOW IN THE LATE AFTERNOON IS OVER THE WRN DACKS.
WE INCREASED THE POPS TO LIKELY THERE. THE 12Z KALB SOUNDING IS
VERY DRY...AND IT WILL TAKE A LITTLE TIME TO SATURATE. THINKING
REMAINS FOR THE HIGHEST TOTALS ACROSS THE SRN DACKS...SRN
GREENS...NRN BERKS...AND PARTS OF THE MOHAWK VALLEY WITH 2-4 INCHES.
AN INCH OR TWO IS POSSIBLE FROM THE CAPITAL REGION NORTHWARD INTO THE
LAKE GEORGE REGION AND WEST INTO THE ERN CATSKILLS. AN INCH OR LESS
IS POSSIBLE IN THE MID HUDSON VALLEY...SRN TACONICS SOUTHWARD.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
A BRIEF VISIT BY HIGH PRESSURE ON FRIDAY...THEN ANOTHER FAST MOVING
SYSTEM WILL AFFECT THE REGION LATE FRIDAY NIGHT AND SATURDAY. THIS
LOW PRESSURE SYSTEM IS TRACKING FROM THE TENNESSEE VALLEY AND WILL
HAVE MORE MOISTURE TO WORK WITH. IT IS NEVERTHELESS AN OPEN WAVE
WITH NOT A LOT OF DYNAMICS. FOR ONCE...THIS SYSTEM LOOKS TO BE
PRETTY MUCH ALL SNOW ACROSS OUR REGION. THERE MIGHT BE A LITTLE
SPOTTY FREEZING DRIZZLE AT THE TAIL END OF THE STORM AS THE MODELS
INDICATE THE CLOUDS WILL LOOSE THEIR ICE AT THAT POINT.
THEREFORE WE CONTINUE OUR THINKING THAT THIS WILL NOT BE A MAJOR
STORM BUT LOOKS TO BRING ADVISORY LEVEL SNOW SOUTH OF CAPITAL
DISTRICT.
THE SNOW LOOKS TO SPREAD INTO THE REGION FROM SOUTHWEST TO NORTHEAST
PRIOR TO OR AROUND DAYBREAK ON SATURDAY AS THE SURFACE LOW TRACKS
WELL SOUTH OF THE MASON DIXON LINE. FAIRLY GOOD ISENTROPIC LIFT AND
A DECENT (BUT NOT IMPRESSIVE) FRONTOGENTIC BAND WILL PASS ACROSS OUR
SOUTHERN AREAS. THERE MIGHT BE A PRETTY SHARP CUTOFF IN THE SNOW
WELL NORTH OF THE CAPITAL DISTRICT. FOR NOW...WE HAVE CATEGORICAL
POPS SOUTH OF THE CAPITAL DISTRICT...LIKELY CAPITAL DISTRICT AND
CHANCES NORTH.
SNOW WILL LIKELY BECOME MODERATE FOR A AWHILE FROM JUST SOUTH OF
ALBANY...BUT THIS WILL BE ANOTHER FAST MOVING SYSTEM WHICH WILL HELP
PREVENT HEAVIER AMOUNTS. LIQUID TO SNOW RATIOS LOOK A LITTLE HIGHER
THAN THE CLIMATOLOGICAL 13:1...ESPECIALLY FROM ALBANY NORTHWARD.
THAT SAID...THE 18Z NAM CAME IN WITH SLIGHTLY HIGHER AMOUNTS OF QPF
AGAIN AND WOULD IMPLY ADVISORY LEVELS RIGHT UP TO THE CAPITAL
DISTRICT. FOR NOW THOUGH...WE WILL CONTINUE WITH THE PREVIOUS
THINKING OF A 2-4 INCH SNOWFALL GREATER CAPITAL REGION...MOHAWK
VALLEY...NORTHERN BERKSHIRES AND SOUTHERN VERMONT. FURTHER
SOUTH...4-6 INCHES CAN BE EXPECTED ACROSS THE CATSKILLS...MUCH OF
THE MID HUDSON VALLEY...SOUTHERN BERKSHIRES...AND LITCHFIELD COUNTY.
THE SNOW LOOKS TO WIND DOWN...AGAIN POSSIBLY ENDING AS LITTLE
FREEZING DRIZZLE DURING THE AFTERNOON ON SATURDAY. (WE DID NOT
MENTION ANY FREEZING DRIZZLE IN THE GRIDS SINCE THE CONFIDENCE OF
THIS HAPPENING WAS STILL RATHER LOW).
HIGH TEMPERATURES LOOK TO BE 25-30 MOST PLACES ON SATURDAY...20 TO
25 WELL NORTH OF ALBANY.
HIGH PRESSURE LOOKS TO BUILD BACK FROM EASTERN CANADA SATURDAY NIGHT
INTO SUNDAY. IF WE CLEAR OUT SATURDAY NIGHT AND GET A DECENT
SNOWPACK...TEMPERATURES COULD GET QUITE COLD BY SUNDAY MORNING. WE
FEEL PRETTY CONFIDENT THE SKY WILL CLEAR...AT LEAST NORTH OF ALBANY.
HOWEVER THE SNOW PACK WILL BE LESS IN THAT VICINITY.
FOR NOW...FOLLOWED A BLEND OF THE MET/MAV GUIDANCE WHICH GAVE US
COLD TEMPS UP NORTH WITH LOTS OF SINGLE NUMBERS...TEENS SOUTH.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
AN AREA OF HIGH PRESSURE WILL MOVE FROM JUST NORTH OF THE REGION ON
SUNDAY MORNING TO JUST EAST OF NORTHERN MAINE BY SUNDAY EVENING.
ENOUGH SUBSIDENCE WILL BE IN PLACE OVER OUR REGION TO ALLOW FOR A
DRY DAY ON SUNDAY WITH PARTLY TO MOSTLY SUNNY SKIES AND TEMPS CLOSE
TO SEASONAL AVERAGES /GENERALLY UPPER 20S TO MIDDLE 30S/.
CLOUDS WILL BEGIN TO INCREASE ON SUNDAY EVENING AS A STRONG STORM
SYSTEM DEEPENS OVER THE NORTHERN GREAT LAKES. A SOUTHERLY LOW LEVEL
JET OF 40-50 KTS AROUND 850 HPA WITH BEGIN TO TRANSPORT WARMER AIR
ALOFT INTO THE REGION. SFC TEMPS WON/T DROP OFF MUCH AT ALL. FOR
NOW...WE HAVE TEMPS BASICALLY STEADY OVERNIGHT...ALTHOUGH THE LOW
MAY WIND UP ACTUALLY BEING IN THE LATE EVENING WITH TEMPS RISING
OVERNIGHT. THE SOUTHERLY FLOW WILL ALLOW FOR SOME WEAK ISENTROPIC
LIFT AND MAY ALLOW FOR A PERIOD OF LIGHT PRECIPITATION OVERNIGHT.
WITH SFC TEMPS BELOW FREEZING IN MANY PLACES...THE PRECIP WILL BEGIN
AS A WINTRY MIX. THE LATEST 12 UTC GFS BUFR SOUNDINGS SHOW THAT A
SNOW/SLEET MIX MAY QUICKLY CHANGE TO RAIN OR FREEZING RAIN DEPENDING
ON THE BOUNDARY LAYER TEMPS. THIS FZRA MAY HANG ON FOR A FEW HOURS
EVEN INTO MONDAY MORNING /MAINLY ACROSS THE SOUTHERN GREENS OR
DACKS/ BEFORE TEMPS WARM UP ENOUGH EVERYWHERE FOR JUST PLAIN RAIN
SHOWERS. TEMPS SHOULD WARM UP WELL INTO THE 40S IN MOST PLACES AS
THE STRONG LOW LIFTS INTO SOUTHERN CANADA.
THE STORM/S COLD FRONT SHOULD PASS THROUGH THE REGION DURING THE
EVENING HOURS ON MONDAY. THIS WILL ALLOW TEMPS TO FALL DOWN
SOMEWHAT AND END THE THREAT FOR WIDESPREAD PRECIP. TEMPS WILL BE
COOLER FOR TUESDAY...BUT STILL A LITTLE ABOVE NORMAL...WITH MAX
TEMPS NEAR 40 FOR THE CAPITAL REGION. IT WILL GENERALLY BE DRY FOR
TUESDAY INTO WEDNESDAY AS WEAK HIGH PRESSURE PASSES OVER THE AREA.
TEMPS ON WED WILL CONTINUE TO BE A LITTLE ABOVE NORMAL FOR MOST
AREAS...WITH UPPER 30S IN THE CAPITAL REGION.
THE MODELS DISAGREE SOMEWHAT FOR THURSDAY. THE LATEST 12 UTC ECMWF
SHOWS A WEAK NORTHERN STREAM CLIPPER STORM MOVING ACROSS THE
AREA...WHILE THE 12 UTC GFS SHOWS A LITTLE DEEPER LOW MOVING TO THE
SOUTH OF THE REGION. IN EITHER SCENARIO...WE WOULD HAVE A CHANCE
OF SOME LIGHT SNOWFALL...SO WILL GO WITH CHC POPS FOR LIGHT
SNOW...ALTHOUGH QPF WILL DEPEND ON JUST HOW THE STORM TRACKS. WITH
THIS BEING VERY FAR OUT...IT/S BOUND TO CHANGE SEVERAL TIMES WITH
SUBSEQUENT MODEL RUNS...SO IT/S A LOW CONFIDENCE FORECAST AT THIS
TIME. FOR NOW...WITH THE EXPECTED CLOUDS/PRECIP...WILL FORECAST
TEMPS A LITTLE CLOSER TO SEASONAL NORMALS...WITH LOWER TO MIDDLE 30S
FOR MANY AREAS.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL PERSIST INTO THE EVENING HOURS AT ALL OUR TAFS.
LOW PRESSURE NORTH OF THE GREAT LAKES REGION...WILL DRAG A COLD
FRONT THROUGH LATER TONIGHT. THERE MIGHT BE A BURST OF SNOW WITH
THIS FEATURE...BUT IT SHOULD NOT LAST LONG AND IFR CONDITIONS LOOK
TO BE BRIEF IF AT ALL. KGFL HAS THE BEST CHANCE OF EXPERIENCING IFR
BUT EVEN HERE FOR NOW...WE KEPT THEM (AS ALL OF THE OTHER TAFS) MVFR
AS CONFIDENCE REMAINS TOO LOW TO INCLUDE. (UNDER 50 PERCENT).
THIS LOW PRESSURE SYSTEM WILL BE QUICK MOVING...WITH ONLY VCSH
EXPECTED BY 08Z/KALB...09Z/KGFL AND 10Z/KPOU. ANY REMAIN SNOW
SHOWERS WILL BE SHORT LIVED AS SUBSIDENCE BEHIND THE COLD FRONT
ACCOMPANYING THE SYSTEM WILL MOVE OVER THE AREA MID TO LATE
FRIDAY MORNING. THIS SUBSIDENCE WILL ALSO HELP DECREASE CLOUD
COVER.
WINDS WILL BE OUT OF THE SOUTH AT 3-8 KTS...WITH KALB
EXPERIENCING SOME GUSTS TO 18 KTS. OVERNIGHT...WINDS WILL SHIFT
BEHIND THE COLD FRONT FROM SOUTH TO W SOMETIME BETWEEN 08Z AND 10Z
THEN INCREASE IN THE MID TO LATE MORNING AND THROUGH THE DAY.
OUTLOOK...
FRI...VFR...NO SIG WX.
SAT...SUB-VFR...CIG. SNOW..ESPECIALLY FROM ALBANY SOUTH.
SUN...VFR...NO SIG WX.
MON-TUE...SUB-VFR...CIG. CHC -RA/-SN.
&&
.HYDROLOGY...
NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH THE
WEEKEND AS ANY PRECIPITATION WHICH FALLS WILL BE IN THE FORM OF SNOW.
A CLIPPER TYPE SYSTEM WHICH IS EXPECTED TO BRIEF BURST OF SNOW TO
MANY LOCATIONS TONIGHT. QPF AMOUNTS WILL BE LESS THAN A QUARTER OF
AN INCH AND SINCE IT WILL BE ALL SNOW NO IMPACT ON ANY WATERSHEDS.
A MORE SIGNIFICANT STORM IS EXPECTED TO TRACK FROM THE TENNESSEE
VALLEY TOWARD THE MIDDLE ATLANTIC COAST BRINGING A GENERALLY LIGHT
TO MODERATE SNOWFALL TO THE REGION LATE FRIDAY NIGHT INTO SATURDAY
WITH THE POTENTIAL FOR HEAVIER SNOW ACROSS THE HIGHER TERRAIN SOUTH
AND EAST OF CAPITAL DISTRICT. SINCE AGAIN IT LOOKS TO BE ALL
SNOW...NO IMPACT ON ANY OUR WATERSHEDS.
ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN
THROUGH THE END OF THE WEEK AS COLD AIR WILL BE IN PLACE ACROSS
THE REGION.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...HWJIV
NEAR TERM...HWJIV
SHORT TERM...HWJIV
LONG TERM...FRUGIS
AVIATION...KGM
HYDROLOGY...HWJIV/GJM
AREA FORECAST DISCUSSION
NWS ALBANY NY
1243 PM EST THU JAN 19 2012
.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO LINGER OVER THE REGION INTO THE
AFTERNOON...THEN A FAST MOVING CLIPPER TYPE SYSTEM WILL IMPACT OUR
REGION LATE BY THIS EVENING...BRINGING SOME LIGHT SNOW AND SNOW
SHOWERS. A MORE SIGNIFICANT STORM MAY IMPACT OUR REGION LATE FRIDAY
NIGHT THROUGH SATURDAY AS IT MOVES FROM THE TENNESSEE VALLEY ACROSS
THE MIDDLE ATLANTIC REGION.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
AS OF 1230 PM...HAD TO BACK OFF THE ARRIVAL OF CLOUDS AND ANY SNOW
PER SURFACE OBS. RADARS INDICATED THE SNOW SHOWERS WERE JUST
ENTERING BUFFALO. THE HRRR EXPERIMENTAL MODEL DOES INDICATE RETURNS
OF NEAR 20 DBZ NOT REACHING ALBANY UNTIL 00Z. PREVIOUS PACKAGE HAD
IT ARRIVING A FEW HOURS. THE AIR IS VERY DRY(AS WAS OUR 12Z RAOB)
AND WILL LIKELY CAUSE THE INITIAL SURGE OF MOISTURE TO EVAPORATE.
NO CHANGE ON HIGH TEMPERATURES BASED ON THIS 12Z RAOB WHICH WHEN
FULLY MIXING THE LOW LEVEL INVERSION GAVE ALBANY A HIGH OF 26. WE
ARE ALREADY 23...SO UPPER 20S LOOKS HERE...LOWER 30S SOUTH AND 20-25
MOST OTHER PLACES...EXCEPT TEENS FAR NORTH AND HIGHEST ELEVATION.
ALL PRECIPITATION SHOULD BE SNOW WITH THIS SYSTEM...BUT FINAL
SNOWFALL AMOUNTS STILL NOT ETCHED IN STONE. FOR NOW...LEFT CURRENT
THINKING FROM TONIGHT ALONE AS WE CONTINUE TO ACCESS ON THE NEW
INCOMING DATA.
FOR THE NEXT SEVERAL HOURS...LOOK FOR SUNSHINE TO BE FOLLOWED BY
RAPID INCREASING CLOUDS FROM THE WEST AND ANY SNOW LIKELY TO HOLD
OFF CERTAINLY FROM THE HUDSON VALLEY EAST...POSSIBLY REACHING OUR
SOUTHERN ADIRONDACKS BY 400 PM.
********PREVIOUS NEAR TERM FORECAST**************
AS OF 950 AM EST...A CLIPPER LOW CONTINUES TO QUICKLY APPROACH
FROM SOUTHEASTERN ONTARIO THIS AFTERNOON. THE HIGH CLOUDS IN
ADVANCE OF A WEAK WARM FRONT CONTINUES TO OVERSPREAD THE REGION.
THE DENSER CANOPY OF CLOUDS IS OVER WRN NY. WE RETOOLED THE CLOUD
TRENDS AND THE POP/WX TRENDS BASED ON THE LATEST NAM/HRRR. THE
WARM ADVECTION LIGHT SNOW/SNOW SHOWERS DOESN/T LOOK LIKE IT WILL
MOVE INTO MOST OF THE REGION UNTIL AFTER 23Z /6 PM/. THE BEST
CHANCE OF SOME SNOW IN THE LATE AFTERNOON IS OVER THE WRN DACKS.
WE INCREASED THE POPS TO LIKELY THERE. THE 12Z KALB SOUNDING IS
VERY DRY...AND IT WILL TAKE A LITTLE TIME TO SATURATE. THINKING
REMAINS FOR THE HIGHEST TOTALS ACROSS THE SRN DACKS...SRN
GREENS...NRN BERKS...AND PARTS OF THE MOHAWK VALLEY WITH 2-4 INCHES.
AN INCH OR TWO IS POSSIBLE FROM THE CAPITAL REGION NORTHWARD INTO THE
LAKE GEORGE REGION AND WEST INTO THE ERN CATSKILLS. AN INCH OR LESS
IS POSSIBLE IN THE MID HUDSON VALLEY...SRN TACONICS SOUTHWARD.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
A BRIEF VISIT BY HIGH PRESSURE ON FRIDAY...THEN ANOTHER FAST MOVING
SYSTEM WILL AFFECT THE REGION LATE FRIDAY NIGHT AND SATURDAY. THIS
LOW PRESSURE SYSTEM WILL BE BETTER ORGANIZED AND ALSO TRACK TO THE
SOUTH OF THE REGION...MOVING OFF THE MID ATLANTIC COAST ON SATURDAY.
HEAVIER SNOW POSSIBLE WITH THIS SYSTEM...BUT NO MAJOR STORM IS
EXPECTED. PRELIMINARY FORECAST SNOWFALL AMOUNTS INDICATE ONE TO FOUR
INCHES OF SNOW POSSIBLE ACROSS THE NORTHERN HALF OF THE FORECAST
AREA...AND 3 TO 7 INCHES OVER THE SOUTH. HOWEVER...WOULD NOT TAKE
MUCH OF A SOUTHWARD SHIFT IN THE TRACK OF THIS LOW PRESSURE SYSTEM
TO REDUCE THESE SNOWFALL AMOUNTS SIGNIFICANTLY.
SOME MODEL DIFFERENCES EXIST IN TERMS OF TIMING OF THIS EVENT.
GFS/ECMWF HAVE SIMILAR TIMING WITH THE SNOW STARTING AROUND OR
SHORTLY AFTER MIDNIGHT FRIDAY NIGHT...AND ENDING BY EARLY AFTERNOON
SATURDAY. THEN NAM STARTS THE SNOW AROUND SUNRISE ON SATURDAY...AND
LINGERS IT INTO EARLY SATURDAY EVENING. FOR NOW HAVE FORECAST CLOSER
TO THE FASTER GFS/ECMWF SOLUTIONS. DESPITE THE TIMING DIFFERENCES...
MODEL FORECASTS OF SNOWFALL AMOUNTS ARE SIMILAR.
STILL COLD THIS PERIOD...HIGHS FRIDAY WILL BE IN THE UPPER TEENS TO
LOWER 30S...LOWS FRIDAY NIGHT IN THE SINGLE NUMBERS AND TEENS...
HIGHS SATURDAY IN THE 20S.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
FAST BROAD CYCLONIC FLOW WITH EMBEDDED UPPER IMPULSES WILL CONTINUE
TO AFFECT OUR REGION THROUGH THE PERIOD...WITH A RELATIVELY STRONG
SYSTEM TO AFFECT THE REGION BETWEEN SUNDAY NIGHT AND MONDAY
EVENING. FIRST...SATURDAY NIGHT AND SUNDAY...HIGH PRESSURE WILL
CONTROL THE WEATHER WITH LOWS IN THE TEENS...SINGLE NUMBERS IN THE
SOUTHERN ADIRONDACKS. HIGHS SUNDAY WITH INCREASING CLOUDS IN THE LOW
TO MID 30S...WITH UPPER 20S IN HIGHER ELEVATIONS.
STRONG UPPER ENERGY APPROACHES SUNDAY NIGHT...WITH INCREASING WARM
ADVECTION AND ISENTROPIC LIFT...AND AREAS OF PRECIPITATION WILL
SPREAD ACROSS THE REGION. LOTS OF UNCERTAINTY ON THE TIMING OF WARM
AIR ALOFT BUT THE GENERAL CONSENSUS FOR SNOW CHANGING TO MIXED
PRECIPITATION VERY LATE SUNDAY NIGHT AND THROUGH MONDAY MORNING.
MIXED PRECIPITATION WOULD INCLUDE SOME POSSIBILITIES FOR FREEZING
RAIN. BY MONDAY AFTERNOON...MOST AREAS OUTSIDE OF THE SOUTHERN
ADIRONDACKS SHOULD SEE A COLD RAIN...WITH SOME MIXED PRECIPITATION
POSSIBLY ALL DAY IN THE SOUTHERN ADIRONDACKS. LOWS SUNDAY NIGHT IN
THE MID 20S TO NEAR 30...SOME TEENS IN THE SOUTHERN ADIRONDACKS.
HIGHS MONDAY IN THE UPPER 30S TO MID 40S...FEW COOLER AREAS IN THE
SOUTHERN ADIRONDACKS.
CONSIDERABLE SPREAD IN GUIDANCE/ENSEMBLES BEYOND MONDAY NIGHT.
SYSTEM MOVES OUT SOME TIME WITHIN THE TIME WINDOW BETWEEN MONDAY
AFTERNOON AND TUESDAY MORNING...WITH COLD ADVECTION BEGINNING.
PRECIPITATION TRANSITIONS TO SNOW SHOWER ACTIVITY. LOWS MONDAY
NIGHT IN THE 20S TO LOWER 30S. DRYING AND CLEARING EITHER LATE
MONDAY NIGHT OR TUESDAY...AND REMAINING DRY THROUGH WEDNESDAY. HIGHS
TUESDAY IN THE 30S TO LOWER 40S. SOME STRONGER COLD ADVECTION
WEDNESDAY WITH HIGHS IN THE MID 30S TO NEAR 40...SOME 20S IN HIGHER
ELEVATIONS.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
VFR CONDITIONS WILL PERSIST THROUGH AT LEAST THE NEXT 6 HOURS AS
HIGH PRESSURE SLIDES EASTWARD TOWARD THE CANADIAN MARITIMES. LOW
PRESSURE NORTH OF THE GREAT LAKES REGION...WITH A COLD FRONT
DRAPING JUST WEST OF THE OHIO RIVER VALLEY...HAS ALREADY STARTED
TO SPREAD MID AND HIGH LEVEL CLOUDS INTO EASTERN NY. CLOUDS WILL
CONTINUE TO INCREASE AND LOWER THROUGHOUT THE DAY...WITH MVFR
CIGS ARRIVING AFTER 00Z/FRIDAY...WHICH WILL BE ACCOMPANIED BY
SNOW. KGFL AND KALB COULD SEE A BRIEF PERIOD OF IFR DURING
SNOWFALL BETWEEN 00Z AND 06Z...BUT CONFIDENCE IS LOW ON TIMING OF
BRIEF IFR CONDITIONS. KGFL AND KALB CAN EXPECT 1 TO 2 INCHES OF
SNOWFALL BY EARLY FRIDAY MORNING. KPOU WILL LIKELY SEE LESS THAN
ONE INCH.
THIS LOW PRESSURE SYSTEM WILL BE QUICK MOVING...WITH ONLY VCSH
EXPECTED BY 08Z/KALB...09Z/KGFL AND 10Z/KPOU. ANY REMAIN SNOW
SHOWERS WILL BE SHORT LIVED AS SUBSIDENCE BEHIND THE COLD FRONT
ACCOMPANYING THE SYSTEM WILL MOVE OVER THE AREA MID TO LATE
FRIDAY MORNING. THIS SUBSIDENCE WILL ALSO HELP DECREASE CLOUD
COVER.
WINDS WILL BE OUT OF THE SOUTH AT 3-8 KTS...WITH KALB
EXPERIENCING SOME GUSTS TO 18 KTS. OVERNIGHT...WINDS WILL SHIFT
BEHIND THE COLD FRONT FROM SOUTH TO SW-W SOMETIME BETWEEN 08Z AND
10Z THEN INCREASE IN THE MID TO LATE MORNING AND THROUGH THE DAY.
OUTLOOK...
FRI...VFR...NO SIG WX.
SAT...MVFR/IFR...SNOW LIKELY.
SUN...VFR...NO SIG WX.
MON-TUE...VFR/MVFR/IFR...CHC -RA/-SN.
&&
.HYDROLOGY...
NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH THE
WEEKEND AS ANY PRECIPITATION WHICH FALLS WILL BE IN THE FORM OF SNOW.
COLD AND DRY WEATHER WILL PREVAIL THROUGH MOST OF TODAY...FOLLOWED
BY A CLIPPER TYPE SYSTEM WHICH IS EXPECTED TO BRING LIGHT SNOW TO
THE REGION LATE TODAY AND TONIGHT. A MORE SIGNIFICANT STORM IS
EXPECTED TO TRACK FROM THE TENNESSEE VALLEY TOWARD THE MIDDLE
ATLANTIC COAST BRINGING A GENERALLY LIGHT TO MODERATE SNOWFALL TO
THE REGION LATE FRIDAY NIGHT INTO SATURDAY WITH THE POTENTIAL FOR
HEAVIER SNOW ACROSS THE HIGHER TERRAIN SOUTH AND EAST OF CAPITAL
DISTRICT.
ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN
THROUGH THE END OF THE WEEK AS COLD AIR WILL BE IN PLACE ACROSS
THE REGION.
FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
MA...NONE.
VT...NONE.
&&
$$
SYNOPSIS...HWJIV/WASULA
NEAR TERM...HWJIV/WASULA
SHORT TERM...GJM
LONG TERM...NAS
AVIATION...KGM
HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
347 PM EST THU JAN 19 2012
.SYNOPSIS...
HIGH PRESSURE MOVES OFFSHORE TONIGHT AS A LOW PRESSURE SYSTEM TRACKS
ACROSS SOUTHEASTERN CANADA. ITS ASSOCIATED COLD FRONT WILL SWING
THROUGH OUR AREA LATE TONIGHT. MORE HIGH PRESSURE WILL BUILD INTO
THE MID ATLANTIC FOR FRIDAY. OVER THE WEEKEND, LOW PRESSURE WILL
DELIVER UNSETTLED WEATHER TO THE REGION SATURDAY, FOLLOWED BY HIGH
PRESSURE SETTLING IN FOR SUNDAY. MORE LOW PRESSURE MAY AFFECT OUR
AREA EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
THE GFS AND WRF-NMM INITIALIZATION LOOKED PRETTY GOOD OFF OF THE 12Z
SOUNDINGS WITH NEITHER MODEL FAVORED. THE ECMWF AND HRRR VERIFIED
THE BEST WITH THE QPF GEOGRAPHICAL EXTENT TO OUR WEST AT 18Z AND THE
FORMER WAS USED TO FINE TUNE THE WX GRIDS FOR TONIGHT. THE MODELS
TRENDED COLDER AND THUS LESS OF A GEOGRAPHICAL MENTION OF RAIN FOR
TONIGHT.
THERE HAS NOT BEEN MUCH OF A MODEL CHANGE WITH RESPECT TO FORCING
AND THE LACK OF MOISTURE WITH WHAT UNDER OTHER CIRCUMSTANCES COULD
HAVE BEEN A MORE DYNAMICAL SYSTEM. THE ACTIVE SNOW AREA TO OUR NW IS
IN THE EXIT REGION OF A 160KT JET WHICH IS FORECAST TO WEAKEN
TONIGHT, BUT STILL WILL PASS ACROSS THE NORTHERN PART OF OUR CWA.
THE ISENTROPIC LIFT (AT 280K) AND THETA E ADVT PART OF THIS EVENT IS
FORECAST TO PASS OFFSHORE BY 00Z. MOST OF THEIR WORK IS TO TRY TO
BRING SOME MSTR INTO OUR CWA, BUT THE SOURCE REGION TO OUR SW IS
QUITE DRY. SO WHEN THE EXIT RGN OF THE JET AND THE FCST DEEP LEVEL
QVEC CONVERGENCE ARRIVE, THE WAA PART OF THE PROGRAM IS OVER. FOR
BETTER OR WORSE THIS DISCONTINUITY GOES A LONG WAY TOWARD GENERATING
THE LOW QPF ALL OF THE MODELS ARE FORECASTING.
NEVERTHELESS GIVEN THE LAST COUPLE OF FEATURES, WE INCREASED POPS
FAR NORTH FOR WATER EQUIVALENTS WHICH WILL PROBABLY BE ONLY SEVERAL
HUNDREDTHS. A QUARTER OF AN INCH OR GREATER SNOW FOLLOWED THE .01
QPF OFF THE ECMWF. THE NEXT SLICE DOWN THROUGH THE I95 CORRIDOR
WE SUGGEST A DUSTING POSSIBLE BY MORNING. FARTHER SE, WARMER
ANTECEDENT SURFACE TEMPS AND LIGHTER INTENSITY MIGHT MIX IN SOME
RAIN, BUT REGARDLESS SHOULD RESULT IN NO EXPECTED DUSTINGS.
THE MODELS TRY TO SHOW A POSSIBLE SECOND QPF MAX ALONG THE NJ COAST
(A COUPLE OF HUNDREDTHS MAYBE) LATE. THIS IS RELATED TO ANOTHER QVEC
CONVERGENCE AREA TRYING TO CATCH UP TO THE PRE FRONTAL ENVIRONMENT.
REASON FOR A POP IN THE POPS TOWARD MORNING THERE.
BECAUSE OF THE SW FLOW AND CLOUDS PRECEDING THE COLD FRONT WE
PREFERRED THE SLIGHTLY HIGHER DATASETS FOR MINS. THE OVERALL
STRENGTH OF THE FCST LLJ IS ABOUT 5-10 KTS LOWER THAN THE 00Z
SOUNDING RUN, SO WE LOWERED LAND BASED GUSTS EAST ABOUT THE SAME AMT.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
A QUIET AND SEASONABLY COLD DAY IS FORECAST FOR FRIDAY. THE SOUNDING
INVERSION NORTHWEST SINKS RATHER QUICKLY SO WE LIMITED THE MENTION
OF FLURRIES IN THE POCONOS TO EARLY. THE FORECAST CONVECTIVE
TEMPERATURES GET PRETTY HIGH, SO WE ARE NOT EXPECTING MUCH HOME
GROWN CUMULUS CLOUDS. BY THE AFTERNOON WE SHOULD START SEEING THE
CIRRUS CLOUDS ASSOCIATED WITH THE NEXT SYSTEM. BASED ON THE FORECAST
FULL SUN MACROS, THE SLIGHTLY WARMER GFS MOS WAS PREFERRED FOR
TEMPERATURES. THERE MAY BE SOME WIND GUSTS IN THE MORNING, BUT
OVERALL THE WINDS WILL BE CLOSER TO SEASONAL AVERAGE AND NOT AS
ROBUST AS THE PREVIOUS COLD FRONTAL PASSAGE.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
ACTIVE WEATHER WILL START OFF THE LONG TERM PERIOD AS ORGANIZING LOW
PRESSURE TO OUR SOUTHWEST APPROACHES FRIDAY NIGHT AND MOVES OVER THE
REGION DURING SATURDAY. MODEL ANALYSIS AND LOOKING AT FCST SOUNDINGS
CONTINUE TO DEPICT THIS AS A MIXED PRECIPITATION EVENT WITH AMPLE
MOISTURE MOVING OVER THE AREA AND SUFFICIENT COLD AIR IN PLACE AT
THE SURFACE TO START THE EVENT. MOST OF THE FORECAST AREA WILL
LIKELY SEE LIGHT SNOW AT THE ONSET OF PRECIPITATION DURING THE EARLY
MORNING HOURS OF SATURDAY. BUT WITH WARM ADVECTION TAKING PLACE
DURING THE COURSE OF SATURDAY, A TRANSITION TO SLEET OR EVEN
FREEZING RAIN AND THEN TO RAIN APPEARS PROBABLE FROM LATE MORNING TO
AFTERNOON FOR OUR SOUTHERN AND CENTRAL COUNTIES. THE TRANSITION TO
WINTRY MIX MAY REACH THE LEHIGH VALLEY, BUT AREAS IN THE POCONOS AND
NORTHWEST NJ LOOK TO RECEIVE PRIMARILY SNOW FROM THIS EVENT, WITH
SEVERAL INCHES OF ACCUMULATION PROBABLE AT THIS TIME. A WINTER STORM
WATCH HAS BEEN ISSUED WITH THIS FORECAST PACKAGE FOR CARBON AND
MONROE COUNTIES IN PA AND SUSSEX COUNTY IN NJ AS ACCUMULATIONS
RANGING FROM 4 TO 7 INCHES ARE ANTICIPATED AT THIS TIME. THE EURO IS
A BIT SLOWER THAN THE GFS WITH THE PASSAGE OF THIS SYSTEM OVER THE
REGION, WITH PRECIPITATION PROGGED TO LAST LONGER INTO SATURDAY
NIGHT. THE GFS WAS FAVORED A BIT WITH THE FASTER ONSET OF
PRECIPITATION WITH THE EVENT, AND ITS ALSO NOTED THAT THE GFS HAS
TRENDED COLDER.
DURING SUNDAY, STRONG HIGH PRESSURE SPREADS SOUTHWEST FROM EASTERN
CANADA AS THE LOW PRESSURE SYSTEM PUSHES EAST AND OUT TO SEA.
QUIETER CONDITIONS GENERALLY ARE EXPECTED TO RETURN SUNDAY, ALTHOUGH
THE MODELS HINT AT THE POSSIBILITY OF A COLD AIR DAMMING SITUATION
DEVELOPING. THE ODDS ON THIS HAPPENING AS EARLY AS SUNDAY ARE NOT
GREAT, AND THE SUNDAY POPS WITH THIS FORECAST ARE LOW. ANOTHER LOW
PRESSURE SYSTEM IS EXPECTED TO AFFECT OUR FORECAST AREA AS EARLY AS
SUNDAY NIGHT IN THE ACTIVE PATTERN. THIS LOW PRESSURE ORGANIZES OVER
THE CENTRAL PLAINS STATES DURING SUNDAY AND TRACKS NORTHEASTWARD TO
THE GREAT LAKES REGION SUNDAY NIGHT THROUGH MONDAY. ITS ASSOCIATED
FRONTS WILL MOVE THROUGH OUR REGION MONDAY AND MONDAY NIGHT.
TEMPERATURES AND THERMAL FIELDS GENERALLY ARE MILD ENOUGH TO SUPPORT
RAIN WITH THE PASSAGE OF THIS SYSTEM, ALTHOUGH COLD AIR THANKS TO
THE RECEDING HIGH TO THE NORTHEAST MAY GENERATE A PERIOD OF SNOW
CHANGING TO FREEZING RAIN FOR A WHILE NORTH. THE EURO AGAIN IS
SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS SYSTEM THROUGH THE
EASTERN STATES. HOWEVER, AT THIS TIME, IT APPEARS THAT THIS SYSTEM
PUSHES EAST OF OUR AREA OVERNIGHT MONDAY. AFTER THAT, THE MODELS ARE
QUITE DIVERGENT (EVEN WITHIN THEMSELVES FROM RUN TO RUN).
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.
THE LATEST 18Z TAFS KEEP A VFR FORECAST GOING, BUT CONFIDENCE IS
LOWEST AT KABE.
A RAPID INCREASE IN MID AND HIGH LEVEL CLOUDINESS WILL CONTINUE THE
REST OF THE AFTERNOON. AS THE HIGH MOVES OFFSHORE, THERE WILL BE A
WINDOW FOR SOME BREEZINESS AND GUSTS FOR AROUND 15 KT WERE
MAINTAINED.
FOR TONIGHT, SNOW SHOWERS AND FLURRIES ASSOCIATED WITH AN
APPROACHING COLD FRONT WILL WORK THEIR WAY INTO THE TERMINALS.
GREATEST CHANCE FOR MVFR AND MAYBE EVEN BRIEFLY VSBY RELATED IFR
RESTRICTIONS IS EXPECTED AT LOCAL AIRPORTS NORTH OF A KRDG-KABE-
KTTN LINE WHERE FCST MOISTURE IS DEEPEST. SO IF WE ARE TOO
OPTIMISTIC ABOUT OUR TERMINALS, KABE IS MOST VULNERABLE. CIGS ARE
FORECAST TO LOWER, BUT REMAIN VFR.
THE COLD FRONT SHOULD CLEAR THE TERMINALS FROM AROUND 09Z TO 11Z FROM
WEST TO EAST AND END ANY SNOW CHANCES. THE GRADIENT BEHIND THE
FRONT IS NOT THAT STRONG AND GUSTS WERE ONLY INCLUDED AT OUR TWO
WINDIEST AIRPORTS, KPHL AND KACY.
VFR CONDITIONS WITH NO CIGS ARE THEN FORECAST TO RETURN DURING
THE DAYLIGHT MORNING.
OUTLOOK...
LOW PRESSURE APPROACHES AND MOVES OVER THE REGION FROM FRIDAY NIGHT
THROUGH SATURDAY, BRINGING THE POTENTIAL FOR MIXED WINTRY
PRECIPITATION TO THE FORECAST AREA. LOWER CEILINGS AND VISIBILITIES
ARE EXPECTED DURING THIS TIMEFRAME. DEPENDING ON HOW QUICKLY THE
SYSTEM EXITS THE REGION, LOWER CONDITIONS MAY EXTEND INTO EARLY
SUNDAY. THE NEXT LOW PRESSURE SYSTEM THAT MAY AFFECT THE AREA,
BRINGING RAIN ALONG WITH LOWERED CEILING AND VISIBILITY VALUES, IS
EXPECTED SUNDAY NIGHT TO MONDAY NIGHT.
&&
.MARINE...
THE SMALL CRAFT ADVISORY WAS EXTENDED INTO FRIDAY MORNING FOR ALL
MARINE AREAS. THE INCREASING SW FLOW SHOULD BRING SMALL CRAFT
CONDITIONS TONIGHT. EVEN THOUGH THE WINDS ARE SOUTHWEST, IN THIS
INSTANCE IT STILL WILL BE COLDER AIR PASSING OVER WARMER WATER.
THERE WILL BE A LULL LATE AS THE COLD FRONT NEARS, BUT THEN COULD BE
A COUPLE OF HOUR WINDOW OF OPPORTUNITY FOR MORE SCA CONDITIONS IN
THE FRESH COLD AIR ADVECTION BEHIND THE COLD FRONT ON FRIDAY
MORNING. AS THE NEXT HIGH PRESSURE SYSTEM THEN NEARS, BOTH WINDS AND
SEAS SHOULD DROP BELOW SMALL CRAFT ADVISORY CRITERIA BY THE
AFTERNOON.
WITH LOW PRESSURE MOVING OVER THE AREA SATURDAY THROUGH SATURDAY
NIGHT, REACHING SMALL CRAFT ADVISORY CRITERIA FOR SEAS IS EXPECTED,
THANKS TO A PERSISTENT EAST TO NORTHEAST FLOW. THE ELEVATED SEAS IN
THE 5 TO 6 FOOT RANGE ON OUR WATERS ARE ANTICIPATED SATURDAY NIGHT
THROUGH SUNDAY, AND THE ELEVATED SEAS MAY EXTEND INTO MONDAY WITH
THE PASSAGE OF ANOTHER WEATHER SYSTEM. WINDS AND GUSTS MAY
OCCASIONALLY REACH ADVISORY LEVELS DURING THIS TIME FRAME.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY
EVENING FOR PAZ054-055.
NJ...WINTER STORM WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY
EVENING FOR NJZ001.
DE...NONE.
MD...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST
FRIDAY FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...KLINE
NEAR TERM...GIGI
SHORT TERM...GIGI
LONG TERM...DELISI/KLINE
AVIATION...DELISI/GIGI/KLINE
MARINE...DELISI/GIGI/KLINE
AREA FORECAST DISCUSSION
NWS MIAMI FL
1221 PM EST THU JAN 19 2012
.AVIATION...VFR CONDITIONS EXPECTED NEXT 24 HRS. SURFACE WINDS
FROM NE AROUND 10 KNOTS SHOULD DECREASE TO AROUND 4-5 KNOTS
OVERNIGHT. SFC HIGH PRESSURE MOVING TO WESTERN ATLANTIC SHOULD
RESULT IN SFC WINDS BECOMING MORE EAST AND INCREASING TO AROUND 10
KTS BY MID MORNING FRIDAY.
&&
.PREV DISCUSSION... /ISSUED 924 AM EST THU JAN 19 2012/
UPDATE...
A WEAK BOUNDARY WAS MOVING THROUGH SOUTH FLORIDA THIS MORNING. THE
ONLY NOTABLE FEATURE IS THE CLOUD COVER ACROSS DEEP SOUTH FLORIDA.
THIS BOUNDARY WILL BECOME EVEN MORE DIFFUSE LATER TODAY...BUT DRIER
AIR WILL CONTINUE TO FILTER INTO THE REGION. SLIGHTLY COOLER
TEMPERATURES ARE EXPECTED THIS AFTERNOON. NO MAJOR UPDATES NEEDED
THIS MORNING.
PREV DISCUSSION... /ISSUED 546 AM EST THU JAN 19 2012/
AVIATION...WEAKENING COLD FRNT APRCHG LK OKEE AREA AND WL MOV
INTO S FLA AND MOV OFF OF THE SE COAST ARND 15Z. MVFR CIGS WITH
LCL IFR OCCURRING AHD OF FRNT. MVFR CIGS PSBL E COAST TERMINALS
11Z-14Z THEN VFR ALL TERMINALS THRU THE END OF THE PD. SFC WNDS
NNW-N < 10 KTS BCMG NNE ALL TERMINALS AFT 18Z AND INCRG 10 TO 15
KTS THEN DCRG < 10 KTS AFT 00Z. POTENTIAL EXISTS THAT AN OFSHR
WND FLOW MAY DVLP LATE TONIGHT BUT NOT IN TAFS ATTM.
PREV DISCUSSION... /ISSUED 324 AM EST THU JAN 19 2012/
DISCUSSION...
LATEST DEW POINT SURFACE ANALYSIS REVEALS LEADING EDGE OF WEAK
FRONTAL BOUNDARY CURRENTLY ACROSS SOUTH CENTRAL FLORIDA BETWEEN
ORLANDO AND LAKE OKEECHOBEE. ANALYSIS OF MODEL GUIDANCE TRACKING THIS
FEATURE INDICATES THE BOUNDARY WILL BE ACROSS SOUTH FLORIDA BY
LATE MORNING AND/OR EARLY AFTERNOON. GLOBAL MODELS IN FACT BRING
IT THROUGH THE AREA BUT THE HIRES MODELS INCLUDING NCEP HIRES NMM
AND ARW AS WELL AS THE LOCAL WRF AND THE RUC INDICATE THE BOUNDARY
WILL SIMPLY DISSIPATE ACROSS THE AREA AS IT MOVES INTO SOUTH
FLORIDA TODAY. EITHER WAY DRIER AIR WILL BE MOVING INTO THE AREA
WITH IT. AHEAD OF IT, RADAR AND SATELLITE INDICATED SOME
CONVECTION EARLIER THIS MORNING MOVING INTO THE GULF WATERS BUT
IT HAS DISSIPATED SINCE THEN AS LOW LEVEL FORCING WITH THE FRONT
WEAKENS AND AS IT MOVES FARTHER AWAY FROM UPPER LEVEL DYNAMICS
WELL REMOVED TO THE NORTH. SO FAR LOOKS LIKE CLOUDS ASSOCIATED
WITH THE APPROACHING BOUNDARY ARE PREVENTING PATCHY FOG FROM
DEVELOPING THIS MORNING ACROSS INTERIOR AREAS OF SOUTH FLORIDA AND
THAT IS LIKELY TO REMAIN LIKE THAT BUT WILL CONTINUE TO MONITOR
JUST IN CASE. FOR THE MOMENT GIVEN TRENDS LEFT THAT OUT OF THE
FORECAST FOR THIS MORNING.
AHEAD OF THE BOUNDARY TODAY THERE WILL BE ONLY A SLIGHT CHANCE OF A
SHOWER, BEST OVER THE COASTAL WATERS, WITH DRIER AIR MASS
GRADUALLY MOVING IN PARTICULARLY BEGINNING AROUND MID TO LATE
MORNING AND INTO THE EARLY AFTERNOON. YET RAIN CHANCES NOT ENOUGH
TO MENTION IN THE FORECAST. AS ALLUDED TO ABOVE, THE BOUNDARY IS
EXPECTED TO STALL AND DISSIPATE BETWEEN MAINLAND SOUTH FLORIDA AND
THE STRAITS THROUGH TONIGHT. TEMPERATURES WILL CONTINUE TO BE WARM
WITH HIGHS IN THE 70S TODAY...AND THEN INTO THE UPPER 70S TO THE
LOWER 80S BY FRIDAY AND INTO THE WEEKEND. WITH THE DRIER AIR AND
EXCELLENT RADIATIONAL COOLING...OVERNIGHT LOWS TONIGHT MAY GET
INTO THE MID 40S ACROSS THE NORTHWEST INTERIOR. ALSO WITH LIGHT
WINDS AND LOW LEVEL FLOW TURNING FROM THE NORTHEAST, IT IS
POSSIBLE THAT PATCHY FOG DEVELOPS INLAND AROUND LAKE OKEECHOBEE
TONIGHT AND AGAIN FRIDAY NIGHT. HOWEVER, CHANCES OF THAT ARE BEST
FRIDAY NIGHT AS BY THEN RETURN FLOW FROM THE ATLANTIC WOULD HAVE
HAD MORE TIME TO MOISTEN UP THE LOW LEVELS A BIT. BUT GIVEN ALL
MOS GUIDANCE DEVELOP IT TONIGHT ALSO, I PUT IT IN THE GRIDS.
OVERALL TONIGHT WILL BE THE COOLEST NIGHT OF THE COMING WEEK. A
CAVEAT HERE IS THAT THE MET GUIDANCE IS SIGNIFICANTLY WARMER THAN
THE MAV FOR NORTHEAST PORTIONS OF THE AREA (PALM BEACH COUNTY). NAM
IS BANKING ON LOT OF CLOUDS RETURNING QUICKLY WITH LOW LEVEL FLOW
SHIFTING FROM THE NE. BUT AT THIS TIME DECIDED TO STICK WITH MAV.
FLOW WILL NOT BE THAT STRONG AND A LAND BREEZE COULD PREVENT THIS
SCENARIO FROM HAPPENING TOO. EKDMOS ENSEMBLE GUIDANCE ALSO SHOWS A
MEAN IN THE MID TO UPPER 50S.
SO WITH THAT SAID, TEMPS TONIGHT WILL STILL BE A COUPLE OF DEGREES
ABOVE NORMAL ACROSS SOUTH FLORIDA WITH A WARMING TREND IN STORE FOR
THE UPCOMING WEEKEND AND INTO THE FIRST PART OF NEXT WEEK WHEN
MODELS GENERALLY AGREE ON HIGH PRESSURE ALOFT BUILDING FROM THE
SOUTHERN GULF OF MEXICO ACROSS CUBA AND INTO THE BAHAMAS, KEEPING
JET STREAM AND STORM TRACKS WELL TO OUR NORTH. GFS IS THE MOST
AGGRESSIVE OF THE MODELS BUILDING THE AFOREMENTIONED HIGH ALOFT BUT
THE MEAN OF THE ENSEMBLE IS STILL CONSISTENT WITH THE SCENARIO AND
SO IS THE ECMWF. BOTTOM LINE, THE ENSUING WARMING TREND WILL RESULT
IN OVERNIGHT LOWS RUNNING CLOSE TO 10 DEGREES ABOVE NORMAL BY LATE
IN THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK ALONG WITH
DAYTIME HIGHS RUNNING AROUND 5 DEGREES ABOVE NORMAL.
IT WILL REMAIN DRY FOR THE MOST PART THROUGH THE WEEKEND WITH A
SLIGHT CHANCE OF SHOWERS MAY BE COMING BACK INTO THE PICTURE BY THE
EARLY TO MIDDLE PART OF NEXT WEEK AS LOW LEVEL MOISTURE SLOWLY
RETURNS FROM THE SOUTH BUT NOT LOOKING TOO PROMISING AT THIS TIME.
MARINE...
A BRIEF SURGE IN WIND OF UP TO 15 TO 20 KNOTS TODAY OFF THE COAST
OF PALM BEACH FROM THE NORTH NORTHEAST WILL RESULT IN A SHORT
LIVED SURGE IN SEAS OF UP TO 6 FEET IN THE GULF STREAM. SO WILL
PUT UP A SMALL CRAFT SHOULD EXERCISE CAUTION FOR THOSE WATERS
TODAY. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW 10 TO 15 KNOTS
AND BELOW 4 FEET INTO THE EARLY PART OF NEXT WEEK.
FIRE WEATHER...
MINIMUM RELATIVE HUMIDITY VALUES TODAY WILL BE BELOW 35 PERCENT IN
AREAS NORTH OF ALLIGATOR ALLEY ACROSS NORTHERN COLLIER, HENDRY,
AND GLADES COUNTIES TODAY FOR CLOSE TO 4 HOURS. HOWEVER ERC VALUES
ACROSS THE AREA REMAIN TOO LOW FOR ANY RED FLAG CONCERNS. AFTER
TODAY, LOW LEVEL MOISTURE WILL BE ON THE INCREASE AND SO NO OTHER
FIRE CONCERNS AT THIS TIME INTO EARLY NEXT WEEK AT THE VERY LEAST.
&&
.PRELIMINARY POINT TEMPS/POPS...
WEST PALM BEACH 55 76 61 77 / - - - -
FORT LAUDERDALE 61 77 66 78 / - - - -
MIAMI 60 77 65 78 / - - - -
NAPLES 52 78 57 78 / - - - -
&&
.MFL WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
AM...NONE.
GM...NONE.
&&
$$
DISCUSSION/MARINE/FIRE...84/AK
AVIATION/RADAR...47/RGH
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1142 AM CST THU JAN 19 2012
.DISCUSSION...
ISSUED 1023 AM CST THU JAN 19 2012
BAND OF LIGHT SNOW THAT IMPACTED NORTH-CENTRAL ILLINOIS EARLY THIS
MORNING IS QUICKLY PUSHING OFF TO THE EAST. 16Z RADAR IMAGERY/SURFACE
OBS SHOW LIGHT SNOW PERSISTING ACROSS ONLY THE FAR NORTHERN KILX
CWA...WITH MOSTLY CLOUDY AND DRY CONDITIONS ELSEWHERE. BASED ON
TRENDS...HAVE UPDATED THE FORECAST TO REMOVE MENTION OF SNOW
EVERYWHERE EXCEPT ALONG/NORTHEAST OF THE I-74 CORRIDOR WHERE IT
WILL CONTINUE FOR THE NEXT COUPLE OF HOURS. NOT EXPECTING MUCH
ADDITIONAL ACCUMULATION...WITH STORM TOTAL AMOUNTS OF AROUND 1
INCH NORTH OF A GALESBURG TO LEXINGTON LINE. ONCE THE SNOW
ENDS...A MOSTLY CLOUDY AND COLD AFTERNOON WILL TAKE SHAPE ACROSS
THE ENTIRE AREA. TEMPERATURES WILL RISE A FEW MORE DEGREES INTO
THE MIDDLE TO UPPER 30S ALONG/SOUTH OF I-70 BY MIDDAY...THEN
READINGS WILL DROP INTO THE 20S THIS AFTERNOON. ELSEWHERE...TEMPS
WILL REMAIN NEARLY STEADY OR SLOWLY FALL INTO THE TEENS.
&&
.AVIATION...
ISSUED 1142 AM CST THU JAN 19 2012
LIGHT SNOW AND LOW CEILINGS AROUND 2500FT WILL CONTINUE TO IMPACT
BOTH KPIA AND KBMI UNTIL 19/20Z...BEFORE THE PRECIP GRADUALLY
SHIFTS OFF TO THE EAST. MEANWHILE...A MID-LEVEL CLOUD DECK WILL
PREVAIL AT THE REMAINING TERMINALS. SATELLITE IMAGERY SHOWS CLOUD
COVER CLEARING OUT ACROSS CENTRAL IOWA...AND BASED ON TIMING TOOLS
AND NAM RH PROFILES...IT APPEARS SKIES WILL CLEAR FROM WEST TO
EAST ACROSS CENTRAL ILLINOIS BETWEEN 21Z AND 23Z. MOSTLY CLEAR
SKIES WILL THEN PREVAIL THROUGH THE EVENING...BEFORE CLOUDS ONCE
AGAIN BEGIN TO INCREASE LATE TONIGHT INTO FRIDAY MORNING. FORECAST
SOUNDINGS AND TIME-HEIGHT CROSS-SECTIONS SUGGEST CEILINGS
LOWERING TO AROUND 1500FT BETWEEN 15Z AND 17Z. SINCE SOUNDINGS DO
NOT FULLY SATURATE AND LIFT REMAINS WEAK...THINK ANY LIGHT PRECIP
WILL HOLD OFF UNTIL FRIDAY AFTERNOON. WINDS WILL INITIALLY BE FROM
THE N/NW AT 10 TO 15KT TODAY...THEN WILL VEER TO EASTERLY AT
AROUND 10KT BY FRIDAY MORNING.
BARNES
&&
.PREV DISCUSSION...
ISSUED 245 AM CST THU JAN 19 2012
SHARP ARCTIC COLD FRONT IS ABOUT TO MOVE INTO THE NORTHWEST TIP OF
THE CWA AT 08Z...OVERALL EXTENDING FROM EAST CENTRAL WISCONSIN TO
AROUND KANSAS CITY. TEMPERATURES QUICKLY DROP OFF INTO THE SINGLE
DIGITS AS CLOSE AS CENTRAL IOWA. AREA OF LIGHT SNOW SO FAR HAS
MAINLY BEEN BEHIND THE FRONT. UPSTAIRS...VERY TIGHT UPPER FLOW
CONTINUES...WITH EVENING UPPER AIR ANALYSIS SHOWING A SCREAMING
150+ KNOT JET AT 300 MB FROM AROUND SEATTLE SOUTHEAST INTO
MISSOURI.
MAIN FORECAST CHALLENGE WITH THIS PACKAGE IS WITH PRECIPITATION
TYPES FRIDAY AND FRIDAY NIGHT. THE EFFECTS OF THE CURRENT SYSTEM
ARE A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
LATEST HRRR MODEL SWEEPS THE FRONT ACROSS THE CWA THIS MORNING...
LINGERING THROUGH MIDDAY ACROSS THE FAR SOUTHEAST. BEST LIFT WITH
THIS FRONT IS STILL EXPECTED OVER THE NORTHEAST THIRD OF THE
CWA...WITH 1-2 INCHES OF SNOW EXPECTED NORTH OF A BLOOMINGTON TO
DANVILLE LINE THROUGH EARLY AFTERNOON. SHARP SOUTHERN CUTOFF TO
THE SNOW IS EXPECTED...AND WENT WITH ONLY SLIGHT CHANCES SOUTH OF
A JACKSONVILLE TO TERRE HAUTE LINE. ONLY THE SOUTHEAST CWA IS
EXPECTED TO SEE TEMPERATURES RISE ABOVE FREEZING...WITH MOST OF
THE FORECAST AREA SEEING FALLING DAYTIME TEMPERATURES.
THE FRIDAY STORM SYSTEM CONTINUES TO HAVE SEPARATE CONCERNS...ONE
WITH THE SNOW ACROSS THE NORTH IN THE STRONGER LIFT AND BAROCLINIC
ZONE...AND THE POTENTIAL FOR MIXED PRECIPITATION FURTHER SOUTH
CLOSER TO THE SURFACE FEATURES. SNOW-WISE...BEST LIFT STILL
EXPECTED JUST TO OUR NORTH ACROSS NORTHERN ILLINOIS...BUT 2-3
INCHES IS LIKELY AS FAR SOUTH AS GALESBURG AND PEORIA FRIDAY INTO
FRIDAY EVENING. FURTHER SOUTH...FORECAST SOUNDINGS SHOWING A
WEDGE OF WARM AIR AROUND 900 MB MOVING IN LATER FRIDAY AFTERNOON
AND ESPECIALLY DURING THE EVENING. THE NAM IS MOST PRONOUNCED WITH
THIS AROUND CHAMPAIGN AND MATTOON...WHILE THE GFS IS FURTHER SOUTH
TOWARD LAWRENCEVILLE AND THE LOCAL WRF IN BETWEEN. EVAPORATIVE
COOLING WOULD FAVOR MORE OF A SLEET/SNOW MIXTURE INITIALLY...THEN
SOME FREEZING RAIN AND SLEET IN THE EVENING BEFORE SWITCHING OVER
TO SNOW LATE TONIGHT. WILL INCLUDE SOME LOW ICE ACCUMULATIONS IN
AREAS MAINLY BETWEEN I-72 AND I-70...WITH LOCATIONS FROM MATTOON
TO PARIS WITH THE HIGHEST AMOUNTS OF AROUND 0.05 INCH OR SO. MAY
NEED TO CONSIDER WINTER WEATHER ADVISORIES IN SOME PARTS OF THE
CWA...BUT ENOUGH MODEL VARIABILITY EXISTS TO PRECLUDE ISSUING ONE
AT THIS TIME.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
PRECIPITATION TO BE OUT OF THE AREA BEFORE SUNRISE SATURDAY...WITH
HIGH PRESSURE RESULTING IN DRY WEATHER. FOCUS IN THE LONGER TERM
SHIFTS TO A DIGGING SHORTWAVE WHICH WILL CROSS THE MIDDLE OF THE
NATION SUNDAY NIGHT AND MONDAY. FOLLOWED THE SLOWER ECMWF/CANADIAN
SOLUTIONS...WHICH FAVOR RAIN FOR THE MOST PART AND A CHANGEOVER TO
SNOW AS THE PRECIPITATION ENDS SUNDAY NIGHT. MODEL SOLUTIONS ARE
CLOSER TO EACH OTHER ON THE NEXT WAVE WHICH CROSSES MIDWEEK...WITH
THE NEXT SHOT OF PRECIPITATION.
ASIDE FROM THE COLD START TO THE WEEKEND...TEMPERATURES MUCH OF
THIS PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1023 AM CST THU JAN 19 2012
.DISCUSSION...
ISSUED 1023 AM CST THU JAN 19 2012
BAND OF LIGHT SNOW THAT IMPACTED NORTH-CENTRAL ILLINOIS EARLY THIS
MORNING IS QUICKLY PUSHING OFF TO THE EAST. 16Z RADAR IMAGERY/SURFACE
OBS SHOW LIGHT SNOW PERSISTING ACROSS ONLY THE FAR NORTHERN KILX
CWA...WITH MOSTLY CLOUDY AND DRY CONDITIONS ELSEWHERE. BASED ON
TRENDS...HAVE UPDATED THE FORECAST TO REMOVE MENTION OF SNOW
EVERYWHERE EXCEPT ALONG/NORTHEAST OF THE I-74 CORRIDOR WHERE IT
WILL CONTINUE FOR THE NEXT COUPLE OF HOURS. NOT EXPECTING MUCH
ADDITIONAL ACCUMULATION...WITH STORM TOTAL AMOUNTS OF AROUND 1
INCH NORTH OF A GALESBURG TO LEXINGTON LINE. ONCE THE SNOW
ENDS...A MOSTLY CLOUDY AND COLD AFTERNOON WILL TAKE SHAPE ACROSS
THE ENTIRE AREA. TEMPERATURES WILL RISE A FEW MORE DEGREES INTO
THE MIDDLE TO UPPER 30S ALONG/SOUTH OF I-70 BY MIDDAY...THEN
READINGS WILL DROP INTO THE 20S THIS AFTERNOON. ELSEWHERE...TEMPS
WILL REMAIN NEARLY STEADY OR SLOWLY FALL INTO THE TEENS.
BARNES
&&
.AVIATION...
ISSUED 543 AM CST THU JAN 19 2012
CONDITIONS WILL BE PRIMARILY VFR AT ALL TAF SITES THROUGH THE
PERIOD. A QUICK MOVING WINTER SYSTEM WILL BRING TEMPO SNOW/MVFR
CIGS/VIS TO PIA/BMI/CMI THIS MORNING THROUGH ABOUT NOON...WHILE
SPI/DEC JUST WILL HAVE VCSH AND SCATTERED AT 2.5KFT. ONCE SYSTEM
PASSES CLOUDS HEIGHTS WILL RISE AGAIN AND WILL BE LEFT WITH JUST
CIRRUS CLOUDS FROM THIS AFTERNOON THROUGH TONIGHT. WINDS WILL BE
SOUTHWEST AHEAD OF THE FRONT BUT QUICKLY SWITCH TO NORTHWEST
BEHIND THE FRONT. EXPECT NORTHERLY WINDS THIS AFTERNOON THROUGH
THIS EVENING...BECOMING NORTHEAST OVERNIGHT. TIGHT TEMP GRADIENT
BEHIND FRONT WILL BRING SOME STRONGER WINDS...BUT GRADIENT WEAKENS
A FEW HOURS BEHIND THE FRONT SO WINDS WILL DECREASE REST OF THE
PERIOD.
AUTEN
&&
.PREV DISCUSSION...
ISSUED 245 AM CST THU JAN 19 2012
SHARP ARCTIC COLD FRONT IS ABOUT TO MOVE INTO THE NORTHWEST TIP OF
THE CWA AT 08Z...OVERALL EXTENDING FROM EAST CENTRAL WISCONSIN TO
AROUND KANSAS CITY. TEMPERATURES QUICKLY DROP OFF INTO THE SINGLE
DIGITS AS CLOSE AS CENTRAL IOWA. AREA OF LIGHT SNOW SO FAR HAS
MAINLY BEEN BEHIND THE FRONT. UPSTAIRS...VERY TIGHT UPPER FLOW
CONTINUES...WITH EVENING UPPER AIR ANALYSIS SHOWING A SCREAMING
150+ KNOT JET AT 300 MB FROM AROUND SEATTLE SOUTHEAST INTO
MISSOURI.
MAIN FORECAST CHALLENGE WITH THIS PACKAGE IS WITH PRECIPITATION
TYPES FRIDAY AND FRIDAY NIGHT. THE EFFECTS OF THE CURRENT SYSTEM
ARE A SECONDARY CONCERN.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT...
LATEST HRRR MODEL SWEEPS THE FRONT ACROSS THE CWA THIS MORNING...
LINGERING THROUGH MIDDAY ACROSS THE FAR SOUTHEAST. BEST LIFT WITH
THIS FRONT IS STILL EXPECTED OVER THE NORTHEAST THIRD OF THE
CWA...WITH 1-2 INCHES OF SNOW EXPECTED NORTH OF A BLOOMINGTON TO
DANVILLE LINE THROUGH EARLY AFTERNOON. SHARP SOUTHERN CUTOFF TO
THE SNOW IS EXPECTED...AND WENT WITH ONLY SLIGHT CHANCES SOUTH OF
A JACKSONVILLE TO TERRE HAUTE LINE. ONLY THE SOUTHEAST CWA IS
EXPECTED TO SEE TEMPERATURES RISE ABOVE FREEZING...WITH MOST OF
THE FORECAST AREA SEEING FALLING DAYTIME TEMPERATURES.
THE FRIDAY STORM SYSTEM CONTINUES TO HAVE SEPARATE CONCERNS...ONE
WITH THE SNOW ACROSS THE NORTH IN THE STRONGER LIFT AND BAROCLINIC
ZONE...AND THE POTENTIAL FOR MIXED PRECIPITATION FURTHER SOUTH
CLOSER TO THE SURFACE FEATURES. SNOW-WISE...BEST LIFT STILL
EXPECTED JUST TO OUR NORTH ACROSS NORTHERN ILLINOIS...BUT 2-3
INCHES IS LIKELY AS FAR SOUTH AS GALESBURG AND PEORIA FRIDAY INTO
FRIDAY EVENING. FURTHER SOUTH...FORECAST SOUNDINGS SHOWING A
WEDGE OF WARM AIR AROUND 900 MB MOVING IN LATER FRIDAY AFTERNOON
AND ESPECIALLY DURING THE EVENING. THE NAM IS MOST PRONOUNCED WITH
THIS AROUND CHAMPAIGN AND MATTOON...WHILE THE GFS IS FURTHER SOUTH
TOWARD LAWRENCEVILLE AND THE LOCAL WRF IN BETWEEN. EVAPORATIVE
COOLING WOULD FAVOR MORE OF A SLEET/SNOW MIXTURE INITIALLY...THEN
SOME FREEZING RAIN AND SLEET IN THE EVENING BEFORE SWITCHING OVER
TO SNOW LATE TONIGHT. WILL INCLUDE SOME LOW ICE ACCUMULATIONS IN
AREAS MAINLY BETWEEN I-72 AND I-70...WITH LOCATIONS FROM MATTOON
TO PARIS WITH THE HIGHEST AMOUNTS OF AROUND 0.05 INCH OR SO. MAY
NEED TO CONSIDER WINTER WEATHER ADVISORIES IN SOME PARTS OF THE
CWA...BUT ENOUGH MODEL VARIABILITY EXISTS TO PRECLUDE ISSUING ONE
AT THIS TIME.
LONG TERM...SATURDAY THROUGH WEDNESDAY...
PRECIPITATION TO BE OUT OF THE AREA BEFORE SUNRISE SATURDAY...WITH
HIGH PRESSURE RESULTING IN DRY WEATHER. FOCUS IN THE LONGER TERM
SHIFTS TO A DIGGING SHORTWAVE WHICH WILL CROSS THE MIDDLE OF THE
NATION SUNDAY NIGHT AND MONDAY. FOLLOWED THE SLOWER ECMWF/CANADIAN
SOLUTIONS...WHICH FAVOR RAIN FOR THE MOST PART AND A CHANGEOVER TO
SNOW AS THE PRECIPITATION ENDS SUNDAY NIGHT. MODEL SOLUTIONS ARE
CLOSER TO EACH OTHER ON THE NEXT WAVE WHICH CROSSES MIDWEEK...WITH
THE NEXT SHOT OF PRECIPITATION.
ASIDE FROM THE COLD START TO THE WEEKEND...TEMPERATURES MUCH OF
THIS PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL.
GEELHART
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
410 PM EST THU JAN 19 2012
.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
SIGNIFICANT SNOW ACCUMULATIONS FRIDAY/FRIDAY NIGHT WILL BE THE MAIN
CONCERN FOR THE SHORT TERM. A WINTER WEATHER ADVISORY WILL BE ISSUED
FOR LATE MORNING FRIDAY THROUGH FRIDAY NIGHT FOR APPROXIMATELY
NORTHERN TWO THIRDS OF THE FORECAST AREA.
ACCUMULATING LIGHT SNOW THIS AFTERNOON HAS SHIFTED WELL SOUTH OF
ROUTE 30 LATE THIS AFTERNOON...AND WILL CONTINUE TO SAG SOUTHWARD
THROUGH THE REMAINDER OF THE LATE AFTERNOON HOURS AS AXIS OF LOW
LEVEL FRONTOGENESIS PUSHES SOUTH OF THE FORECAST AREA. FURTHER TO
THE NORTH...LAKE EFFECT SNOW SHOWERS HAVE BEEN INCREASING IN
INTENSITY WITH FAIRLY STRONG 850 HPA/LAKE DELTA TEMPS ON THE ORDER
OF 20 TO 23 DEGREES. RUC SOUNDINGS SUGGEST A NEARLY ISOTHERMAL LAYER
FROM 850 TO 700 HPA WHICH IS LIMITING DEPTH OF THIS LAKE GENERATED
INSTABILITY WITH LAKE INDUCED EQUILIBRIUM HEIGHTS ON THE ORDER OF
ABOUT 5K FT. ANOTHER NEGATIVE FACTOR POINTING AGAINST SIGNIFICANT
LAKE EFFECT SNOW ACCUMULATIONS IS MUCH DRIER MID LEVEL AIR THAT WAS
WORKED INTO THE SOUTHERN GREAT LAKES REGION BEHIND THE SYSTEM WHICH
BROUGHT THE ACCUMULATING SNOW TODAY. THIS MARGINAL LAKE EFFECT SETUP
WILL CONTINUE FOR MUCH OF THE EVENING AND INTO THE OVERNIGHT...AND A
FEW LOCATIONS MAY PICK UP A HALF INCH TO AN INCH OF ADDITIONAL
ACCUMULATION BEFORE INVERSION HEIGHTS CRASH MORE SUBSTANTIALLY
DURING THE OVERNIGHT HOURS. AREAS AWAY FROM LAKE EFFECT
CLOUDS/PRECIP SHOULD CLEAR THIS EVENING. A WEAKENING GRADIENT WITH
SFC RIDGE AXIS BUILDING IN COMBINED WITH THIS CLEARING SHOULD
ALLOW FOR VERY COLD TEMPS TONIGHT INTO THE SINGLE DIGITS ABOVE
ZERO. SOME INCREASE IN HIGH CLOUDS IS EXPECTED LATE TONIGHT THAT
MAY LEVEL OUT TEMPERATURES AFTER 09Z.
ATTENTION WILL THEN TURN TO WHAT WILL BE A VERY FAST MOVING UPPER
LEVEL SYSTEM THAT IS APPROACHING THE PACIFIC NORTHWEST COAST AT THIS
TIME. LOW LEVEL WINDS WILL BACK SOUTHWESTERLY ON FRIDAY AHEAD OF
THIS TROUGH WHICH WILL SET UP A PERIOD OF INTENSE ISENTROPIC UPGLIDE
FRIDAY AFTERNOON/EARLY EVENING OVER THE SHALLOW RETREATING ARCTIC
AIR MASS. STRONG FRONTOGENETIC FORCING ALSO TO DEVELOP IN THE
850/700 LAYER AS THIS LOW LEVEL FLOW RAMPS UP. 12Z NAM REMAINS A
SLIGHTLY SLOWER AND FURTHER NORTH OUTLIER IN REGARDS TO THIS
SYSTEM...WITH 09Z SREF GENERALLY LENDING SUPPORT TO THE MORE RUN TO
RUN CONSISTENT GFS/ECMWF. GENERALLY UTILIZED A PREDOMINATELY
SREF/GFS/ECMWF BLEND FOR THIS FORECAST WITH A MUCH SMALLER
WEIGHTING TOWARD NAM. PERIOD OF MOST INTENSE SNOWFALL APPEARS TO
BE SHAPING UP IN THE 21Z-03Z TIMEFRAME WITH BEST COLOCATION OF
STRONGER SYNOPTIC LIFT WITH FAVORABLE DENDRITIC GROWTH ZONE.
MODEL QPF FROM 12Z SUITE OF MODELS STILL TEND TO SUPPORT MAINLY
HIGH END ADVISORY LEVEL SNOW ACCUMULATIONS WHEN CONSIDERING
EXPECTED SNOW TO LIQUID RATIOS ON THE ORDER OF 15:1 ACROSS THE
NORTH.
CONCERN WITH THESE TYPE OF INTENSE LOW/MID LEVEL BAROCLINIC ZONES IS
FOR AREAS OF ENHANCED BANDING WHICH COULD PUSH SOME AREAS INTO LOW
END WARNING ACCUMULATIONS. 12Z GFS MODEL CROSS SECTIONS STILL
INDICATE RELATIVELY HIGH STATIC STABILITY ATOP THIS LOW LEVEL
FRONTOGENESIS FORCING WHICH MAY TEND TO DISCOURAGE SMALLER SCALE
INTENSE BANDING...AND A BROADER RESPONSE IN UPWARD VERTICAL MOTION
FIELDS. SYSTEM ALSO WILL BE VERY PROGRESSIVE WITH SOME INDICATIONS
OF ISENTROPIC UPGLIDE WEAKENING SLIGHTLY FROM WEST TO EAST INTO
NORTHEAST INDIANA BY EVENING. TAKING THE ABOVE FACTORS INTO
CONSIDERATION HAVE OPTED TO GO WITH A HIGH END WINTER WEATHER
ADVISORY FOR SNOW ACCUMULATIONS OF 3 TO 7 INCHES NORTHERN TWO
THIRDS...WITH THE HIGHER ACCUMULATIONS EXPECTED FAR NORTHERN
INDIANA/SOUTHERN LOWER MICHIGAN. WINDS NOT EXPECTED TO BE AN OVERLY
HUGE CONCERN WITH THIS SYSTEM...BUT A BRIEF PERIOD IN THE 21Z-03Z
TIMEFRAME OF 1 TO 2 INCH PER HOUR SNOWFALL RATES APPEARS TO BE A
GOOD POSSIBILITY. IN TRENDING MORE TOWARD GFS...HAVE CONFINED MIXED
PRECIP MENTION TO A CHANCE OF SLEET ACROSS THE SOUTH BUT THIS WILL
NEED TO BE WATCHED IN FUTURE FORECASTS ONCE CONFIDENCE IN LOW LEVEL
THERMAL FIELDS INCREASES. SNOW WILL BEGIN TO WANE LATE FRIDAY NIGHT
WITH INDICATIONS OF FAR SOUTHEAST GETTING INTO SOME ENHANCED
SNOWFALL AS A PIECE OF EASTERN PACIFIC SHORT WAVE DIGS MORE
AGGRESSIVELY INTO THE OHIO RIVER VALLEY.
&&
.LONG TERM...
SUNDAY THROUGH THURSDAY
SIG PATTERN ADJUSTMENT TO OCCUR IN THE LONG TERM PERIOD AS REX BLOCK
RIDGING SHIFTS WEST OVER ALASKA...WITH SUBSTANTIAL UPPER LEVEL
TROUGHING EXPECTED THERE BY THIS WEEKEND. THIS WILL RESULT IN A
SWITCH BACK TO FAST WESTERLY GENERALLY MILD FLOW...WITH EMBEDDED FAST
MOVING IMPULSES PROVIDING PERIODIC CHANCES FOR RAIN/SNOW. THIS WILL
OCCUR AFTER THE ADVECTION OF A POTENT MID LATITUDE CYCLONE EARLY
NEXT WEEK...A SYSTEM WHICH COULD BRING A SUBSTANTIAL AMOUNT OF
RAIN/WIND/AND EVEN THUNDERSTORMS TO THE AREA SUNDAY NIGHT INTO
MONDAY MORNING. ECMWF/GFS/AND GEFS SOLUTIONS CONTINUE TO REMAIN
NEARLY PHASED PER HEIGHT SOLUTIONS IN THE PERIOD...WITH INCREASED
FORECAST CONFIDENCE IN THE PERIOD.
SAT-MON...FRIDAY SYSTEM WILL BE IN THE PROCESSES OF EXITING THE REGION
WITH A LOW CHANCE FOR LINGERING LIGHT SNOW FAR SE SAT AM. WEAK
SUBSIDENT REGIME WITH SFC RIDGING WILL SUPPORT GRADUAL EROSION OF
LINGERING LOW CLOUDS...WITH WINDS VEERING SE THROUGH THE SAT PERIOD.
MEANWHILE...A SIG MID LEVEL TROUGH IS EXPECTED TO DIG INTO THE SW
CONUS AND BEGIN TO EJECT TOWARD THE REGION. SYSTEM INFLUENCE TO THE
LOCAL AREA WILL BEGIN ON SUNDAY...WITH REFLECTED LL SOUTHERLY FLOW
INCREASING THROUGH THE SUNDAY DAY PERIOD. LINGERING BAROCLINIC ZONE
IN PLACE OVER THE CENTRAL PLAINS WILL INTERACT WITH THE EJECTING MID
LEVEL DISTURBANCE TO SUPPORT ROBUST SFC PRESSURE FALLS...SUPPORTING
RAPID SFC CYCLOGENESIS. THIS WILL ALLOW SIG LL THETA-E ADV TO ENSUE
SUNDAY IN THE REGION WITH SIG SFC LAYER DEWPOINT RISES INTO SUNDAY
NIGHT. STAUNCH LL FLOW WITH A 60 TO 70 KNOT LLJ PROGGED IN THE
ECMWF...WILL BE MORE THAN ENOUGH TO SUPPORT DEEP LAYER THETA-E
RISES. SNOWPACK IN PLACE WILL LIKELY SUPPORT A SATURATED BL WITH
DRIZZLE AND FOG EXPECTED TO DEVELOP SUNDAY AFTERNOON INTO THE
EVENING...LIKELY PERSISTING THROUGH SUNDAY NIGHT. ECMWF H7-H3 LAYER
ANALYSIS REVEALS A RATHER IMPRESSIVE EML WITH STEEP MID LEVEL LAPSE
RATES GIVEN STRONG LOW CENTERED WAA. H85 THETA-E APPROACHES 325K BY
LATE SUNDAY NIGHT...WITH SW INDICES NEGATIVE...INDICATING A GOOD
ENVIRONMENT FOR ELEVATED THUNDERSTORMS. HAVE INTRODUCED A LOW CHANCE
THUNDER AT THIS POINT. ALBEIT SMALL...THERE IS A CONCERN FOR SEVERE
WEATHER GIVEN INDICATED H5 JETLET IN EXCESS OF 90 KNOTS...WHICH
WOULD BE CAPABLE QLCS JET DRIVEN CELLS. PERHAPS THE BIGGEST CONCERN
ATTM IS FOR INCREASED FLOODING CONCERNS GIVEN FULL SNOWPACK MELT
WITH THE POTENTIAL FOR HEAVY RAIN. WILL HIGHLIGHT IN AN ESF.
NEGATIVE TROUGH TILT INDICATED IN FORECAST MODELS SUGGEST A NW TRACK
ADJUSTMENT PER THE SFC LOW...WITH A SLOWER SYSTEM ARRIVAL
POSSIBLE...IN ADDITION TO WARMER THERMAL FIELDS. HENCE DROPPED THE
SNOW MENTION SUN NIGHT/TRIMMED MONDAY SNOW MENTION/AND ADJUSTED
TEMPS UP. CAA WILL DOMINATE MONDAY WITH FALLING TEMPS IN THE DAYTIME
PERIOD LIKELY. LINGERING LIGHT SNOW SHOWERS WILL BE POSSIBLE MAINLY
NW.
TUE-THUR...FAST WNW PAC ORIGIN FLOW IS EXPECTED INTO THE REGION WITH
ROCKIES ENHANCED IMPULSES EXPECTED. STRONGEST PROGGED IMPULSE
REMAINS IN THE WED PERIOD AND HAVE RETAINED POPS THEN...OPTING TO
KEEP THE RAIN/SNOW WORDING GIVEN WARM THERMAL FIELDS.
OTHERWISE...ADJUSTED TEMPS UP SOME...WITH ABOVE NORMAL TEMPS LIKELY
ONCE AGAIN.
&&
.AVIATION...
18Z TAFS...MODERATE SNOW WILL CONTINUE TO AFFECT KFWA THROUGH 20Z
BEFORE DIMINISHING AS AN UPPER LEVEL DISTURBANCE AND ASSOCIATED
LOW LEVEL FRONTAL BOUNDARY SAG SOUTHEAST. PERIODS OF LAKE EFFECT
SNOW SHOWERS WILL ALSO AFFECT KSBN THROUGH AT LEAST EARLY EVENING.
HAVE CARRIED MVFR CONDITIONS TO COVER THIS LAKE EFFECT POTENTIAL
ALTHOUGH SOME SHORT LIVED IFR VSBYS MAY BE ASSOCIATED WITH THE
STRONGER BANDS. NORTHWEST WINDS TO CONTINUE TO DROP OFF IN SPEED
THROUGH THE REMAINDER OF THE NIGHT...EVENTUALLY BECOMING SOUTHEAST
BY FRIDAY MORNING. DID MAINTAIN MVFR CIGS AT TERMINALS THIS
EVENING DUE TO TRAJECTORIES UPWIND OF LAKE MICHIGAN AND WEAKENING
LOW LEVEL FLOW...ALTHOUGH CONFIDENCE IS LOW IN DURATION OF THESE
MVFR CIGS WITH A POSSIBILITY OF VFR CIGS AT KFWA EVEN BY LATER
THIS AFTERNOON. CONDITIONS TO DETERIORATE AGAIN ON
FRIDAY...ESPECIALLY TOWARD THE END OF THIS FORECAST PERIOD AS NEXT
SYSTEM BRINGS A MORE SIGNIFICANT ROUND OF SNOW TO NORTHERN INDIANA.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...WINTER WEATHER ADVISORY FROM 10 AM EST /9 AM CST/ FRIDAY TO 7 AM
EST /6 AM CST/ SATURDAY FOR INZ003>009-012-014-016>018.
MI...WINTER WEATHER ADVISORY FROM 10 AM FRIDAY TO 7 AM EST SATURDAY
FOR MIZ077>081.
OH...WINTER WEATHER ADVISORY FROM 10 AM FRIDAY TO 7 AM EST SATURDAY
FOR OHZ001-002-004-005-015-016.
LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST FRIDAY FOR LMZ043-046.
&&
$$
SHORT TERM...MARSILI
LONG TERM...JC
AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1158 AM MST THU JAN 19 2012
.UPDATE...
1158 AM MST THU JAN 19 2012
LATEST SATELLITE IMAGERY SHOWS THAT THE COLD FRONT IS MOVING
EASTWARD AWAY FROM ITS EARLIER POSITION NEAR THE KS/CO BORDER.
TEMPERATURES IN EASTERN CO HAVE WARMED INTO THE 50S...WHILE
TEMPERATURES IN SOUTHWESTERN NE ARE STRUGGLING TO LEAVE THE MID
TEENS. HAVE ADJUSTED HIGH TEMPERATURES TO BE WARMER IN CO AND
COOLER WELL BEHIND THE FRONT.
CJS
&&
.DISCUSSION...
220 AM MST THU JAN 19 2012
EARLY MORNING WV IMAGERY AND RUC H5 ANALYSIS SHOW BROAD TROUGH
EXTENDING FROM GREAT LAKES ACROSS THE EASTERN US...WITH W/NW FLOW
EXTENDING ACROSS THE CENTRAL PART OF THE COUNTRY. AT THE SURFACE A
STRONG COLD FRONT HAS SETTLED OVER THE CWA...WITH A 20F SPREAD IN
TEMPS BETWEEN THE SW PART OF THE CWA AND THE NE.
TODAY-SATURDAY...WITH DRY CONDITIONS EXPECTED THE MAIN FORECAST
CONCERN WILL CONTINUE TO BE TEMPERATURES AS THE PREVIOUSLY MENTIONED
FRONT AND ASSOCIATED BAROCLINIC ZONE LINGERS ACROSS PORTIONS OF
NORTHWEST KANSAS AND SOUTHWEST NEBRASKA. 30F SPREAD IN HIGH TEMPS
CURRENTLY FORECAST FROM THE EAST TO THE WEST TODAY...WITH AREAS WEST
OF THE FRONT APPROACHING THE MID 50S...AND EAST OF THE FRONT IN THE
MID/UPPER 20S. BETWEEN THESE EXTREMES IT IS DIFFICULT TO PIN DOWN
HIGH TEMPS CONSIDERING THE EXTREME TEMPERATURE GRADIENT THAT
WILL BE IN PLACE...SO HAVE USED A GENERAL BLEND OF PREVIOUS FORECAST
AND LATEST SHORT-RANGE GUIDANCE. TEMPS WILL BEGIN TO MODERATE SOME
ACROSS EASTERN PARTS OF THE AREA FRIDAY...BEFORE A BACKDOOR COLD
FRONT REINFORCES SHALLOW COLD AIR MASS FRIDAY AFTERNOON/EVENING.
SHALLOW COLD AIR MASS BEGINS TO SCOUR OUT WITH TEMPS MODERATING
AHEAD OF SHORTWAVE TROUGH MOVING TOWARDS THE GREAT BASIN...THOUGH
THERE WILL STILL BE A 15-20F GRADIENT FROM EAST TO WEST.
SATURDAY NIGHT...SHORTWAVE TROUGH MOVES TOWARDS THE CENTRAL ROCKIES
SATURDAY NIGHT...WITH INCREASING LARGE SCALE ASCENT OVER THE CWA
AFTER 06Z. NAM/GFS BOTH ARE WEAKER/QUICKER WITH THIS SYSTEM...AND
KEEP CONDITIONS DRY OVER CWA. ECMWF CONTINUES TO SHOW
STRONGER/WETTER SOLUTION. I WAS HESITANT TO JUMP ON THE WET ECMWF
SOLUTION YET...WITH TIMING/STRENGTH STILL IN QUESTION. WITH THE
AMOUNT OF LIFT PRESENT AND LIMITED MOISTURE ADVECTION I COULDNT RULE
OUT SOME FLURRIES IN THE NORTH...BUT WASNT CONFIDENT ENOUGH TO ADD
DURING THIS CYCLE.
DR
FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...RELATIVELY QUIET WEATHER
EXPECTED THROUGH THE ENTIRE PERIOD. A COLD FRONT WILL MOVE THROUGH
THE REGION MONDAY NIGHT AND TUESDAY...HOWEVER PRECIPITATION CHANCES
APPEAR THEY WILL STAY SOUTH AND EAST OF THE LOCAL FORECAST AREA. IT
WILL BRING A PERIOD OF GUSTY NORTH WINDS...PROBABLY TUESDAY
MORNING....AND COOLER TEMPERATURES TUESDAY AND WEDNESDAY...ALBEIT
STILL ABOVE NORMAL.
024
&&
.AVIATION...
1050 AM MST THU JAN 19 2012
FOR THE 18Z TAFS...ARCTIC COLD CURRENTLY LOCATED NEAR THE KS/CO STATE
LINE. THIS FEATURE WILL CREATE SOME UNCERTAINTY AT KGLD WITH RESPECT
TO TIMING OF WIND SHIFTS...BUT A GENERAL VEER FROM EAST/SOUTHEAST TO
THE SOUTH IS EXPECTED DURING THE AFTERNOON HOURS. ALSO OF NOTE ARE LOW
IFR CIGS CURRENTLY LOCATED JUST TO THE NORTH OF KGLD...BUT THESE LOW
CIGS ARE EXPECTED TO REMAIN TO THE NORTH OF THE TERMINAL PER WIND
DIRECTION. OTHERWISE...A GENERAL WIND SHIFT WILL TAKE PLACE FROM
THE EAST TO THE SOUTH/SOUTHWEST AS THE FRONT RETREATS SLOWLY TO THE
EAST...WITH A WIND SHIFT TO THE NORTHWEST NEAR THE END OF THE PERIOD
FRI MID/LATE MORNING.
050
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1050 AM MST THU JAN 19 2012
.DISCUSSION...
220 AM MST THU JAN 19 2012
EARLY MORNING WV IMAGERY AND RUC H5 ANALYSIS SHOW BROAD TROUGH
EXTENDING FROM GREAT LAKES ACROSS THE EASTERN US...WITH W/NW FLOW
EXTENDING ACROSS THE CENTRAL PART OF THE COUNTRY. AT THE SURFACE A
STRONG COLD FRONT HAS SETTLED OVER THE CWA...WITH A 20F SPREAD IN
TEMPS BETWEEN THE SW PART OF THE CWA AND THE NE.
TODAY-SATURDAY...WITH DRY CONDITIONS EXPECTED THE MAIN FORECAST
CONCERN WILL CONTINUE TO BE TEMPERATURES AS THE PREVIOUSLY MENTIONED
FRONT AND ASSOCIATED BAROCLINIC ZONE LINGERS ACROSS PORTIONS OF
NORTHWEST KANSAS AND SOUTHWEST NEBRASKA. 30F SPREAD IN HIGH TEMPS
CURRENTLY FORECAST FROM THE EAST TO THE WEST TODAY...WITH AREAS WEST
OF THE FRONT APPROACHING THE MID 50S...AND EAST OF THE FRONT IN THE
MID/UPPER 20S. BETWEEN THESE EXTREMES IT IS DIFFICULT TO PIN DOWN
HIGH TEMPS CONSIDERING THE EXTREME TEMPERATURE GRADIENT THAT
WILL BE IN PLACE...SO HAVE USED A GENERAL BLEND OF PREVIOUS FORECAST
AND LATEST SHORT-RANGE GUIDANCE. TEMPS WILL BEGIN TO MODERATE SOME
ACROSS EASTERN PARTS OF THE AREA FRIDAY...BEFORE A BACKDOOR COLD
FRONT REINFORCES SHALLOW COLD AIR MASS FRIDAY AFTERNOON/EVENING.
SHALLOW COLD AIR MASS BEGINS TO SCOUR OUT WITH TEMPS MODERATING
AHEAD OF SHORTWAVE TROUGH MOVING TOWARDS THE GREAT BASIN...THOUGH
THERE WILL STILL BE A 15-20F GRADIENT FROM EAST TO WEST.
SATURDAY NIGHT...SHORTWAVE TROUGH MOVES TOWARDS THE CENTRAL ROCKIES
SATURDAY NIGHT...WITH INCREASING LARGE SCALE ASCENT OVER THE CWA
AFTER 06Z. NAM/GFS BOTH ARE WEAKER/QUICKER WITH THIS SYSTEM...AND
KEEP CONDITIONS DRY OVER CWA. ECMWF CONTINUES TO SHOW
STRONGER/WETTER SOLUTION. I WAS HESITANT TO JUMP ON THE WET ECMWF
SOLUTION YET...WITH TIMING/STRENGTH STILL IN QUESTION. WITH THE
AMOUNT OF LIFT PRESENT AND LIMITED MOISTURE ADVECTION I COULDNT RULE
OUT SOME FLURRIES IN THE NORTH...BUT WASNT CONFIDENT ENOUGH TO ADD
DURING THIS CYCLE.
DR
FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...RELATIVELY QUIET WEATHER
EXPECTED THROUGH THE ENTIRE PERIOD. A COLD FRONT WILL MOVE THROUGH
THE REGION MONDAY NIGHT AND TUESDAY...HOWEVER PRECIPITATION CHANCES
APPEAR THEY WILL STAY SOUTH AND EAST OF THE LOCAL FORECAST AREA. IT
WILL BRING A PERIOD OF GUSTY NORTH WINDS...PROBABLY TUESDAY
MORNING....AND COOLER TEMPERATURES TUESDAY AND WEDNESDAY...ALBEIT
STILL ABOVE NORMAL.
024
&&
.AVIATION...
1050 AM MST THU JAN 19 2012
FOR THE 18Z TAFS...ARCTIC COLD CURRENTLY LOCATED NEAR THE KS/CO STATE
LINE. THIS FEATURE WILL CREATE SOME UNCERTAINTY AT KGLD WITH RESPECT
TO TIMING OF WIND SHIFTS...BUT A GENERAL VEER FROM EAST/SOUTHEAST TO
THE SOUTH IS EXPECTED DURING THE AFTERNOON HOURS. ALSO OF NOTE ARE LOW
IFR CIGS CURRENTLY LOCATED JUST TO THE NORTH OF KGLD...BUT THESE LOW
CIGS ARE EXPECTED TO REMAIN TO THE NORTH OF THE TERMINAL PER WIND
DIRECTION. OTHERWISE...A GENERAL WIND SHIFT WILL TAKE PLACE FROM
THE EAST TO THE SOUTH/SOUTHWEST AS THE FRONT RETREATS SLOWLY TO THE
EAST...WITH A WIND SHIFT TO THE NORTHWEST NEAR THE END OF THE PERIOD
FRI MID/LATE MORNING.
050
&&
.GLD WATCHES/WARNINGS/ADVISORIES...
KS...NONE.
NE...NONE.
CO...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS GRAY ME
501 PM EST THU JAN 19 2012
.SYNOPSIS...
WEAK LOW PRESSURE WILL MOVE EAST THROUGH NEW ENGLAND AND THE GULF
OF MAINE OVERNIGHT. LOW PRESSURE WILL SHIFT INTO THE MARITIMES ON
FRIDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. HIGH PRESSURE
WILL SHIFT EAST FRIDAY NIGHT AS WEAK LOW PRESSURE APPROACHES NEW
ENGLAND FROM THE SOUTHWEST. LOW PRESSURE WILL PASS OUT TO SEA
SOUTH OF NEW ENGLAND ON SATURDAY. HIGH PRESSURE WILL BUILD IN FROM
THE NORTHWEST SATURDAY NIGHT AND SUNDAY. LOW PRESSURE LIFTING
NORTHEAST OUT OF THE NORTHERN GREAT LAKES WILL DRIVE A COLD FRONT
TOWARD NEW ENGLAND ON MONDAY. THE FRONT WILL CROSS THE AREA MONDAY
NIGHT WITH A TRAILING TROUGH OF LOW PRESSURE MOVING THROUGH THE
REGION ON TUESDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST
ON WEDNESDAY. LOW PRESSURE WILL PASS SOUTH OF NEW ENGLAND ON
THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE...
ALSO...LATEST HRRR MODEL UPDATE HAS A GOOD HANDLE WITH OCEAN
EFFECT SNOW SHOWERS ENTERING ROCKINGHAM AND YORK COUNTIES THIS
HOUR. HAVE UPPED POPS QUITE A BIT FOR THIS AREA TO ACCOUNT FOR
THIS LOCAL PCPN. -SHSN WILL SPREAD NORTHWARD IN THE NEXT HOUR OR
TWO INTO THE PWM AND POSSIBLY THE NHZ AREAS.
HAVE UPDATED GRIDS TO INCREASE CLOUD COVER OVERNIGHT TO OVERCAST
CONDITIONS WITH ADVISORIES IN EFFECT. REST OF THE GRIDS WILL
REMAIN RELATIVELY UNCHANGED WITH ADVISORIES CONTINUING FOR THE ERN
HALF OF THE FORECAST AREA.
PREV DISC...
WEAK LOW PRESSURE APPROACHING FROM THE WEST WILL BRING A
BRIEF ROUND OF LIGHT TO MODERATE SNOW TO THE REGION OVERNIGHT. LOW
PRESSURE STILL FORECAST TO RE-DEVELOP OVER SOUTHERN NEW ENGLAND
AND MOVE INTO THE GULF OF MAINE BUT MODELS NOT AS STRONG WITH THIS
SYSTEM TODAY AND QPF FOR THE EVENT HAS DROPPED OFF SOMEWHAT.
EXPECT SNOW TO PUSH INTO THE CONNECTICUT VALLEY EARLY THIS EVENING
AND QUICKLY OVER-SPREAD THE REMAINDER OF THE FORECAST AREA THROUGH
MIDNIGHT. WILL STILL BE GOING WITH THE CURRENT ADVISORIES FOR
SOUTHERN AND COASTAL MAINE EXCLUDING YORK COUNTY FOR THE OVERNIGHT
HOURS. HAVE NOT CHANGED ACCUMULATIONS MUCH FROM YESTERDAY WITH 2
TO 4 INCHES OF ACCUMULATION EXPECTED ACROSS MUCH OF NEW HAMPSHIRE
AND EXTREME SOUTHWEST MAINE. REMAINDER OF SOUTHERN AND COASTAL
MAINE WILL SEE 3 TO 6 INCHES OF SNOWFALL THROUGH EARLY FRIDAY
MORNING. EXPECT SNOW TO QUICKLY END IN NEW HAMPSHIRE AND SOUTHWEST
MAINE BEFORE DAYBREAK ON FRIDAY. SHOULD BE A MUCH WARMER NIGHT
WITH TEMPS IN THE LOWER TO MID TEENS IN THE NORTH AND MID TEENS TO
LOWER 20S IN THE SOUTH.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
HIGH PRESSURE BUILDING IN FROM THE WEST WILL BRINGING CLEARING
SKIES AND MOSTLY SUNNY WEATHER TO MOST OF THE AREA ON FRIDAY.
SHOULD SEE MORNING CLOUDS CLEARING OUT OF THE MOUNTAINS AND FAR
EASTERN ZONES BY NOON. EXPECT TEMPS TO RANGE THROUGH THE TEENS IN
THE NORTH AND THROUGH THE 20S AND LOWER 30S IN THE SOUTH.
MID HIGH LEVEL CLOUDINESS WILL BE ON THE INCREASE FRIDAY NIGHT AS
WEAK OVER-RUNNING PATTERN SHIFTS INTO THE NORTHEAST AHEAD OF LOW
PRESSURE MOVING INTO THE MID ATLANTIC STATES. WILL INTRODUCE
LOW CHANCE POPS INTO SOUTHERN NEW HAMPSHIRE AFTER MIDNIGHT BUT
EXPECT LITTLE IF ANY ACCUMULATION THROUGH SATURDAY MORNING. LOW
TEMPS WILL RANGE FROM ZERO TO 10 BELOW IN THE NORTH AND 5 TO 15
ABOVE IN THE SOUTH.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
MODELS TRACK WEAK SFC LOW OFF THE MID ATLANTIC COAST E AND OUT TO
SEA ON SATURDAY. THIS WILL PRODUCE -SN ACROSS THE FCST AREA WITH
LGT ACCUMULATIONS PSBL. HIGHEST CHC OF SN AND HIGHEST
ACCUMULATIONS OVER MORE SRN AREAS CLOSER TO THE LOW WITH LOWEST
CHC AND ACCUMULATION TO THE N. VERTICAL TEMP PROFILE CD ENOUGH TO
SUPPORT ALL SN FOR THIS EVENT.
THE LOW MOVES OUT TO SEA FAIRLY QUICKLY WITH -SN ENDING FROM W TO E
IN THE AFTERNOON. HIGH PRES FOLLOWS WITH FAIR WX SATURDAY NGT AND
SUNDAY. THE HIGH MOVES OUT TO THE E SUNDAY NGT AS THE UPR LVL
RIDGE CRESTS ALONG THE E COAST. A STRONG UPR LVL CUTOFF SYSTEM
OVER THE UPPER MID WEST CREATES A FAIRLY STRONG SFC LOW OVER THE
GREAT LAKES THAT WILL TRACK SLOWLY E WITH A TRAILING CD FNT
EXTENDING TO THE S. AHEAD OF THIS SYSTEM INCREASING S SW FLOW FROM
SFC TO H5 BRINGS IN MUCH WARMER AIR ALOFT AND EVENTUALLY TO THE
SFC AS PRCP EVENTUALLY MOVES IN LATE SUNDAY NGT AND MONDAY. MAY BE
SOME -SN OR MIXED SN AND ICE TO BEGIN WITH BUT GRADUALLY PRPC
CHANGES OVER TO RA FOR MONDAY AND MONDAY NGT THOUGH SOME -FZRA
STILL PSBL ACROSS THE NRN TIER OF ZONES WHERE IT WILL TAKE THE
LONGEST TO SCOUR OUT THE CD AIR AT THE SFC.
THE CD FNT MOVES THRU BY TUESDAY MORNING WITH COLDER AIR FOLLOWING
THE FNT AS TEMPS LIKELY TO FALL DURING THE DAY AFTER MILD PREDAWN
READINGS. A SECONDARY UPR LVL TROF MOVES THRU WHICH MAY PRODUCE A
FEW -SHSN BUT THE N/MT ZONES HAVE THE BEST CHC OF -SHSN DUE TO
DEVELOPING UPSLOPE FLOW IN THE CD AIR ADVECTION BEHIND THE FNT.
HIGH PRES BRINGS FAIR WX WEDNESDAY FOLLOWED BY A FAST MOVING SFC
LOW THAT WILL TRACK TO OUR S BRINGING THE CHC OF -SN WEDNESDAY NGT
AND THURSDAY.
GENERALLY USED GFS40...HPC QPF AND BLEND OF MAV/MET MOS FOR SATURDAY
THRU SATURDAY NGT. USED GMOS FOR REST OF THE LONG TERM FCST...
EXCEPT USED A BLEND OF GFS40 AND MEX MOS GUIDANCE FOR MAX AND MIN
TEMPS.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
SHORT TERM...MVFR/IFR CEILINGS AND VSBY DEVELOPING THIS
EVENING...IMPROVING TO VFR ON FRIDAY. VFR FRIDAY NIGHT.
LONG TERM /SATURDAY THROUGH MONDAY/...IFR PSBL WITH -SN SATURDAY.
IFR OR LIFR PSBL WITH MIXED PRCP DEVELOPING LATE SUNDAY NGT AND
CONTINUING THRU MONDAY.
&&
.MARINE...
SHORT TERM...SMALL CRAFT ADVISORY IN EFFECT THIS EVENING THROUGH FRIDAY.
LONG TERM /SATURDAY THROUGH MONDAY/...CONDITIONS BELOW SCA LEVELS
SATURDAY THRU SUNDAY NGT...THEN INCREASE TO SCA LEVELS OR PSBL
GALES MONDAY INTO MONDAY NGT IN STRENGTHEN S SW FLOW AHEAD OF THE
CD FNT. WINDS SHIFT TO THE W AS THE FNT MOVES OUT TO SEA AND CONT AT
SCA OR PSBL GALE LEVELS ON TUESDAY.
&&
.GYX WATCHES/WARNINGS/ADVISORIES...
ME...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 11 AM EST
FRIDAY FOR MEZ012>014-019>022-024>028.
NH...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 7 PM EST
FRIDAY FOR ANZ150>154.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
424 PM EST THU JAN 19 2012
.SYNOPSIS...
A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW
EARLY TONIGHT. HIGH PRESSURE WILL THEN ALLOW FOR A BRIEF BREAK
FROM WINTRY PRECIPITATION EARLY ON FRIDAY. LOW PRESSURE, MOVING
NORTHEAST FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, BRINGING A
WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A ZONAL FLOW AS A TROUGH MOVES ACROSS THE EASTERN GREAT LAKES.
AT THE SURFACE, A 998MB LOW IS LOCATED NORTHEAST OF MICHIGAN. A COLD
FRONT EXTENDS SOUTH OF THIS FEATURE INTO OHIO. AHEAD OF THE
FRONT, AN AREA OF LIGHT SNOW IS PUSHING INTO EASTERN OHIO AND
WESTERN PA. THE SNOW INCREASES IN INTENSITY CLOSER TO THE FRONT,
WITH MODERATE SNOW REPORTED A FEW OBS UPSTREAM IN NORTHWEST OHIO.
THIS EVENING...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST TOWARD THE
AREA, WITH THE RUC/HRRR WIND SHIFT SUPPORTING THE FRONT REACHING A
ZANESVILLE-NEW PHILADELPHIA-FRANKLIN LINE BY 00Z. LIGHT SNOW WILL
INCREASE IN INTENSITY AT TIMES, REDUCING VISIBILITIES THIS
EVENING. A FACTOR IN THE SNOWFALL ACCUMULATION AT LEAST INITIALLY
WILL BE SURFACE TEMPS, WITH AREAS SOUTH OF I-70 IN THE MID TO
UPPER 30S. THIS WILL LIMIT SNOWFALL ACCUMULATION THERE INITIALLY.
THUS FORECAST INTO THE EARLY EVENING IS FOR AROUND AN INCH NORTH
OF I-70 AND FOR A HALF OF AN INCH OR LESS SOUTHWARD.
TONIGHT...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST ACROSS THE
UPPER OHIO VALLEY, PUSHING SOUTHEAST OF THE RIDGES BY 03Z FRI.
THE BEST CHANCE FOR SNOW ACCUMULATION AND POTENTIALLY HAZARDOUS
TRAVEL WILL BE AROUND SUNSET THROUGH MIDNIGHT AS SNOW PUSHES ACROSS THE
AREA. SNOW WILL BEGIN TO TAPER OFF BEHIND THE FRONT WITH JUST A
FEW LINGERING SNOW SHOWERS ALONG THE I-80 CORRIDOR AND EASTERN
RIDGES BY DAWN. MOSTLY AROUND AN ADDITIONAL INCH OF SNOWFALL WILL
BE POSSIBLE TONIGHT, WITH 1 TO 3 POSSIBLE IN LOCALIZED AREAS AND
THE EASTERN RIDGES. STRONG COLD AIR ADVECTION IN THE WAKE OF THE
FRONT WILL ALLOW FOR LOWS RANGING FROM THE TEENS ACROSS NORTH-
CENTRAL WV TO THE LOWER TEENS NORTH OF THE PITTSBURGH METRO.
TOTAL SNOWFALL FOR THIS AFTERNOON THROUGH TONIGHT WILL GENERALLY
BE 1 TO 2 INCHES ACROSS MUCH OF THE AREA. LOCALIZED AREAS OF UP
TO 3 INCHES WILL BE POSSIBLE NORTH OF THE PITTSBURGH METRO AND
ACROSS THE EASTERN RIDGES WITH COOLER TEMPS AT THE ONSET OF THE
SNOW. IN ADDITION, MOST LOWLAND AREAS SOUTH OF I-70 WILL SEE LESS
AN INCH. ALTHOUGH SNOW AMOUNTS FORECAST ARE MOSTLY SUB-ADVISORY
AMOUNTS, WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS NORTH
OF PITTSBURGH DUE TO TIMING OF THE SNOW IMPACTING THE EVENING
COMMUTE.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
THERE IS OPERATIONAL MODEL AGREEMENT TO BEGIN THIS PERIOD THAT
HIGH PRESSURE WILL KEEP THE EARLY PORTION OF THE DAY DRY ACROSS
THE AREA. AFTER 18Z, AN INVERTED TROUGH OF LOW PRESSURE EXTENDING
FROM TEXAS INTO THE TENNESSEE VALLEY WILL SERVE TO DRAW MOISTURE
FROM THE GULF INTO THE AREA AS ANOTHER WAVE MOVES ACROSS THE
MIDWEST. THIS WILL CREATE A COMPLICATED MIXED PRECIPITATION
SCENARIO FOR THE UPPER OHIO VALLEY FOR FRIDAY NIGHT INTO EARLY
SATURDAY.
FORECAST CONSISTS OF A BLEND OF THE NAM/ECMWF/SREF WITH THE GFS
CONSIDERED A COLD OUTLIER. SURFACE LOW AND INVERTED TROUGH FROM
THE TN VALLEY WILL MERGE WITH NORTHERN STREAM WAVE AS IT SHIFTS INTO
THE MID-ATLANTIC FRIDAY NIGHT INTO SATURDAY MORNING. NAM/ECMWF
INDICATE THE 1000-850MB 1300M THICKNESS LINE STRADDLING NORTH-
CENTRAL WV AT THE ONSET FRIDAY NIGHT AND THEN SHIFTING NORTHWARD
TO THE PITTSBURGH METRO BY DAWN ON SATURDAY. THUS, FORECAST IS
FOR SNOW ACROSS THE AREA AT THE ONSET OF PRECIPITATION AFTER 00Z
SATURDAY, AND CHANGE TO FZRA AND TO RAIN OVERNIGHT SOUTH OF THE
MASON-DIXON LINE. NORTH OF THE MASON-DIXON LINE TO THE PITTSBURGH
METRO, FORECAST IS FOR AN EXTENDED PERIOD OF A WINTRY MIX WITH ICE
ACCUMULATIONS OF A TENTH TO TWO TENTHS OF AN INCH. NORTH OF THE
PITTSBURGH METRO, PRECIP WILL BE SNOW FOR THE MAJORITY, WITH 3 TO
6 INCHES POSSIBLE FOR THE I-80 CORRIDOR. WITH COLD AIR HANGING
ACROSS THE EASTERN RIDGES, A WINTER STORM WATCH HAS BEEN POSTED
FOR GARRETT COUNTY AND THE WESTMO/FAYETTE RIDGES FOR THE POTENTIAL
OF OVER A QUARTER INCH OF ICE. OTHERWISE, A TENTH TO TWO TENTHS OF
ICE ARE NOT OUT OF THE QUESTION FOR AREAS BETWEEN MASON-DIXON LINE
AND SOUTH OF THE I-80 CORRIDOR AND MAY LEAD TO AN ADVISORY.
SATURDAY...WINTRY MIX OF PRECIPITATION WILL COME TO AN END DURING
THE MORNING HOURS AS HIGH PRESSURE BEGINS TO BUILD IN FROM THE
NORTHWEST.
FOR TEMPS, WITH COLD AIR BUILT IN BEHIND THE FRONT ON FRIDAY, TEMPS
WILL LIKELY REMAIN BELOW FREEZING THROUGHOUT THE DAY, WITH HIGHS
RANGING FROM THE LOWER 20S ACROSS THE I-80 CORRIDOR TO THE LOWER
30S ACROSS PORTIONS OF EASTERN OHIO AND NORTH-CENTRAL WV. WARM AIR
ADVECTION WILL TAKE PLACE SOUTH OF THE PITTSBURGH METRO FRIDAY
NIGHT, WITH TEMPS RISING INTO THE MID 30S BY DAWN. TEMPS WILL
REMAIN FAIRLY STEAD NORTH OF THE PITTSBURGH METRO IN THE MID TO
UPPER 20S. TEMPS WILL CONTINUE TO MODERATE ON SATURDAY, CONSISTING
OF A MAV/MET BLEND, RANGING FROM NEAR 30 ACROSS THE I-80 CORRIDOR
TO THE LOWER 40S ACROSS NORTH-CENTRAL WV.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
PER RECENT SREF MODEL OUTPUT, EXPECT DRY CONDITIONS FOR SATURDAY
NIGHT INTO SUNDAY EVENING. THEN BLEND OF RECENT SREF AND ECMWF MODEL
OUTPUT SHOW A COLD FRONT, COMING EAST FRONT THE ROCKIES, WILL BRING
SHOWERS LATE SUNDAY NIGHT INTO MONDAY NIGHT. THERE CAN BE A
SUFFICIENT COLD POOL IN THE WAKE OF THE FRONTAL PASSAGE TO CAUSE A
POSSIBLE CHANGE TO SNOW SHOWERS LATE MONDAY NIGHT AND TUESDAY.
WITH THE UPPER LEVEL JETSTREAM MAINTAINING A WAVY ZONAL PATTERN,
BLEND OF RECENT ECMWF AND GFS MODEL OUTPUT SHOWS A SECOND COLD
FRONT, COMING EAST FROM THE ROCKIES, CAN PROVIDE SHOWERS WEDNESDAY
NIGHT AND THURSDAY. THE PRECIPITATION TYPE THEN CAN BE RAIN OR SNOW
AS SURFACE TEMPERATURES WILL BE MAINLY IN THE 30S.
REGARDING OTHER ASPECTS OF THE TEMPERATURE FORECAST THIS PERIOD,
ZONAL JETSTREAM PATTERN SHOULD MAINTAIN VALUES GENERALLY WARMER THAN
NORMAL, WITH MONDAY AND THURSDAY HAVING VALUES MORE THAN 10 DEGREES
ABOVE NORMAL. TUESDAY SHOULD BE THE COLDEST DAY, BUT EVEN THEN
VALUES MAY BE NO COLDER THAN NORMAL.
&&
.AVIATION /21Z THURSDAY THROUGH TUESDAY/...
PER BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH NAM AND GFS
LAMP MODEL OUTPUT, EXPECT A PREFRONTAL SNOW BAND, WITH IFR
CONDITIONS, TO CONTINUE SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY
THROUGH 04Z. PREFRONTAL SURFACE WINDS WILL BE FROM THE SOUTHWEST
WITH GUSTS TO 25 KTS. POSTFRONTAL WINDS WILL BE NORTHWEST AND
DECREASE TO 10 KTS BY LATE TONIGHT.
DURING LATE TONIGHT AND FRIDAY MORNING, EXPECT POST-SYSTEM COLD
POOL STRATOCUMULUS CEILINGS TO LIFT THROUGH MVFR LEVELS TO VFR
LEVELS BY MIDDAY.
OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY...
A WINTRY MIX WITH IFR RESTRICTIONS LATE FRIDAY NIGHT AND SATURDAY.
VFR SUNDAY. RAIN SHOWERS WITH POSSIBLE RESTRICTIONS MONDAY AND
MONDAY NIGHT, WITH A POSSIBLE CHANGE TO SNOW SHOWERS TUESDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...WINTER STORM WATCH FROM FRIDAY EVENING THROUGH SATURDAY
MORNING FOR MDZ001.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
PAZ007>009-013>016-022-023.
WINTER STORM WATCH FROM FRIDAY EVENING THROUGH SATURDAY
MORNING FOR PAZ074-076.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
134 PM EST THU JAN 19 2012
.SYNOPSIS...
A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW
THIS AFTERNOON INTO EARLY TONIGHT. LOW PRESSURE, MOVING NORTHEAST
FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY
MIX FOR FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
18Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO
INCREASE POPS EARLY NORTH OF THE I-80 CORRIDOR AS SNOW MOVES IN
EARLY THIS AFTERNOON.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A ZONAL FLOW AS A TROUGH MOVES ACROSS THE EASTERN GREAT LAKES.
AT THE SURFACE, A 999MB LOW IS LOCATED NORTH OF MICHIGAN. A COLD
FRONT EXTENDS SOUTH OF THIS FEATURE ACROSS MICHIGAN AND INTO
NORTHWEST OHIO. AHEAD OF THE FRONT, AN AREA OF LIGHT SNOW IS PUSHING
INTO EASTERN OHIO AND WESTERN PA. THE SNOW INCREASES IN INTENSITY
CLOSER TO THE FRONT, WITH MODERATE SNOW REPORTED A FEW OBS
UPSTREAM IN NORTHWEST OHIO.
THIS AFTERNOON...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST
TOWARD THE AREA, WITH THE RUC/HRRR WIND SHIFT SUPPORTING THE FRONT
REACHING A ZANESVILLE-NEW PHILADELPHIA-FRANKLIN LINE BY 00Z THIS
EVENING. FORECAST CONSISTS OF A BLEND OF THE HRRR/NAM4KM, WITH
LIGHT SNOW REACHING AREAS THE PITTSBURGH METRO AFTER 19Z WITH LIKELY
POPS REACHING THE EASTERN RIDGES OF MD/WV BY 23Z. SNOW WILL
INCREASE IN INTENSITY AT TIMES, REDUCING VISIBILITIES THIS
EVENING. A FACTOR IN THE SNOWFALL ACCUMULATION AT LEAST INITIALLY
WILL BE SURFACE TEMPS, WITH AREAS SOUTH OF I-70 WARMING INTO THE
MID TO UPPER 30S. THIS WILL LIMIT SNOWFALL ACCUMULATION THERE
INITIALLY. THUS FORECAST INTO THE EARLY EVENING IS FOR AROUND AN
INCH NORTH OF I-70 AND FOR A HALF OF AN INCH OR LESS SOUTHWARD.
FOR TEMPS, FORECAST IS A FEW DEGREES WARMER THAN A LAMP/HRRR
BLEND, WITH HIGHS RANGING FROM THE UPPER 30S ACROSS NORTH-CENTRAL
WV TO NEAR 30 ALONG THE I-80 CORRIDOR.
TONIGHT...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST ACROSS THE
UPPER OHIO VALLEY, PUSHING SOUTHEAST OF THE RIDGES BY 03Z FRI.
THE BEST CHANCE FOR SNOW ACCUMULATION AND POTENTIALLY HAZARDOUS
TRAVEL WILL BE AROUND SUNSET THROUGH MIDNIGHT AS SNOW PUSHES ACROSS THE
AREA. SNOW WILL BEGIN TO TAPER OFF BEHIND THE FRONT WITH JUST A
FEW LINGERING SNOW SHOWERS ALONG THE I-80 CORRIDOR AND EASTERN
RIDGES BY DAWN. MOSTLY AROUND AN ADDITIONAL INCH OF SNOWFALL WILL
BE POSSIBLE TONIGHT, WITH 1 TO 3 POSSIBLE IN LOCALIZED AREAS AND
THE EASTERN RIDGES. STRONG COLD AIR ADVECTION IN THE WAKE OF THE
FRONT WILL ALLOW FOR LOWS RANGING FROM NEAR 20 ACROSS NORTH-
CENTRAL WV TO THE MID TO UPPER TEENS ELSEWHERE.
TOTAL SNOWFALL FOR THIS AFTERNOON THROUGH TONIGHT WILL GENERALLY
BE 1 TO 2 INCHES ACROSS MUCH OF THE AREA. LOCALIZED AREAS OF UP
TO 3 INCHES WILL BE POSSIBLE NORTH OF THE PITTSBURGH METRO AND
ACROSS THE EASTERN RIDGES WITH COOLER TEMPS AT THE ONSET OF THE
SNOW. IN ADDITION, MOST LOWLAND AREAS SOUTH OF I-70 WILL SEE LESS
AN INCH. ALTHOUGH SNOW AMOUNTS FORECAST ARE MOSTLY SUB-ADVISORY
AMOUNTS, WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS NORTH
OF PITTSBURGH DUE TO TIMING OF THE SNOW IMPACTING THE EVENING
COMMUTE.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE
FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST
DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE
PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST
IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND
FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE
OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF
PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR
THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK
FOR THESE POTENTIALS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE
DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY.
AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW
ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE
ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO
CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW.
DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH
MOVES EASTWARD INTO THE OHIO VALLEY.
STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE
NORMAL THROUGH THE EXTENDED PERIOD.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
PER BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH NAM AND GFS
LAMP MODEL OUTPUT, EXPECT A PREFRONTAL SNOW BAND, WITH IFR CONDITIONS, TO
MOVE SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY THROUGH 04Z.
PREFRONTAL SURFACE WINDS WILL BE FROM THE SOUTHWEST WITH GUSTS TO
25 KTS. POSTFRONTAL WINDS WILL BE NORTHWEST AND DECREASE TO 10 KTS
BY LATE TONIGHT.
DURING LATE TONIGHT AND FRIDAY MORNING, EXPECT POST-SYSTEM COLD
POOL STRATOCUMULUS CEILINGS TO LIFT THROUGH MVFR LEVELS TO VFR
LEVELS BY MIDDAY.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
A WINTRY MIX WITH RESTRICTIONS LATE FRIDAY NIGHT AND SATURDAY.
VFR SUNDAY. RAIN SHOWERS WITH RESTRICTIONS MONDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
PAZ007>009-013>016-022-023.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1250 PM EST THU JAN 19 2012
.SYNOPSIS...
A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW
THIS AFTERNOON INTO EARLY TONIGHT. LOW PRESSURE, MOVING NORTHEAST
FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY
MIX FOR FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATE MORNING ENHANCED SHORT TERM FORECAST UPDATE HAD BEEN ISSUED
TO SLOW THE ONSET OF SNOW BY A FEW HOURS THIS AFTERNOON.
OTHERWISE, LITTLE CHANGE TO THE GOING FORECAST.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A ZONAL FLOW AS A TROUGH MOVES ACROSS THE GREAT LAKES. AT THE
SURFACE, A 1000MB LOW IS LOCATED NORTH OF MICHIGAN. A COLD FRONT
EXTENDS SOUTHWEST OF THIS FEATURE ACROSS MICHIGAN AND INTO
INDIANA. AHEAD OF THE FRONT, AN AREA OF LIGHT SNOW IS PUSHING INTO THE
NORTHWEST HALF OF OHIO. THE SNOW INCREASES IN INTENSITY CLOSER TO
THE FRONT, WITH MODERATE SNOW REPORTED WITH SEVERAL OBS UPSTREAM
IN INDIANA.
THIS AFTERNOON...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST
TOWARD THE AREA, WITH THE RUC/HRRR WIND SHIFT SUPPORTING THE FRONT
REACHING A ZANESVILLE-NEW PHILADELPHIA-FRANKLIN LINE BY 00Z THIS
EVENING. FORECAST CONSISTS OF A BLEND OF THE HRRR/NAM4KM, WITH
LIGHT SNOW REACHING AREAS NORTH AND WEST OF PITTSBURGH BY 19Z WITH
LIKELY POPS REACHING THE EASTERN RIDGES OF MD/WV BY 23Z. SNOW WILL
INCREASE IN INTENSITY AT TIMES, REDUCING VISIBILITIES THIS
EVENING. A FACTOR IN THE SNOWFALL ACCUMULATION AT LEAST INITIALLY
WILL BE SURFACE TEMPS, WITH AREAS SOUTH OF I-70 WARMING INTO THE
MID TO UPPER 30S. THIS WILL LIMIT SNOWFALL ACCUMULATION THERE
INITIALLY. THUS FORECAST INTO THE EARLY EVENING IS FOR AROUND AN
INCH NORTH OF I-70 AND FOR A HALF OF AN INCH OR LESS SOUTHWARD.
FOR TEMPS, FORECAST IS A FEW DEGREES WARMER THAN A LAMP/HRRR BLEND,
WITH HIGHS RANGING FROM THE UPPER 30S ACROSS NORTH-CENTRAL WV TO
NEAR 30 ALONG THE I-80 CORRIDOR.
TONIGHT...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST ACROSS THE
UPPER OHIO VALLEY, PUSHING SOUTHEAST OF THE RIDGES BY 03Z FRI.
THE BEST CHANCE FOR SNOW ACCUMULATION AND POTENTIALLY HAZARDOUS
TRAVEL WILL BE AFTER SUNSET THROUGH MIDNIGHT AS SNOW PUSHES ACROSS
THE AREA. SNOW WILL BEGIN TO TAPER OFF BEHIND THE FRONT WITH JUST
A FEW LINGERING SNOW SHOWERS ALONG THE I-80 CORRIDOR AND EASTERN
RIDGES BY DAWN. MOSTLY AROUND AN ADDITIONAL INCH OF SNOWFALL WILL BE
POSSIBLE TONIGHT, WITH 1 TO 3 POSSIBLE IN LOCALIZED AREAS AND THE
EASTERN RIDGES. STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT
WILL ALLOW FOR LOWS RANGING FROM NEAR 20 ACROSS NORTH-CENTRAL WV TO
THE MID TO UPPER TEENS ELSEWHERE.
TOTAL SNOWFALL FOR THIS AFTERNOON THROUGH TONIGHT WILL GENERALLY
BE 1 TO 2 INCHES ACROSS MUCH OF THE AREA. LOCALIZED AREAS OF UP
TO 3 INCHES WILL BE POSSIBLE NORTH OF THE PITTSBURGH METRO AND
ACROSS THE EASTERN RIDGES WITH COOLER TEMPS AT THE ONSET OF THE
SNOW. IN ADDITION, AREAS SOUTH OF I-70 WILL SEE AROUND AN INCH.
ALTHOUGH SNOW AMOUNTS FORECAST ARE MOSTLY SUB-ADVISORY AMOUNTS,
WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS NORTH OF
PITTSBURGH DUE TO TIMING OF THE SNOW IMPACTING THE EVENING
COMMUTE.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE
FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST
DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE
PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST
IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND
FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE
OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF
PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR
THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK
FOR THESE POTENTIALS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE
DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY.
AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW
ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE
ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO
CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW.
DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH
MOVES EASTWARD INTO THE OHIO VALLEY.
STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE
NORMAL THROUGH THE EXTENDED PERIOD.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
PER BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH NAM AND GFS
LAMP MODEL OUTPUT, EXPECT A PREFRONTAL SNOW BAND, WITH IFR CONDITIONS, TO
MOVE SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY THROUGH 04Z.
PREFRONTAL SURFACE WINDS WILL BE FROM THE SOUTHWEST WITH GUSTS TO
25 KTS. POSTFRONTAL WINDS WILL BE NORTHWEST AND DECREASE TO 10 KTS
BY LATE TONIGHT.
DURING LATE TONIGHT AND FRIDAY MORNING, EXPECT POST-SYSTEM COLD
POOL STRATOCUMULUS CEILINGS TO LIFT THROUGH MVFR LEVELS TO VFR
LEVELS BY MIDDAY.
OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...
A WINTRY MIX WITH RESTRICTIONS LATE FRIDAY NIGHT AND SATURDAY.
VFR SUNDAY. RAIN SHOWERS WITH RESTRICTIONS MONDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
PAZ007>009-013>016-022-023.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1139 AM EST THU JAN 19 2012
.SYNOPSIS...
A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW
THIS AFTERNOON INTO EARLY TONIGHT. LOW PRESSURE, MOVING NORTHEAST
FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY
MIX FOR FRIDAY NIGHT AND SATURDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
LATE MORNING ENHANCED SHORT TERM FORECAST UPDATE HAD BEEN ISSUED
TO SLOW THE ONSET OF SNOW BY A FEW HOURS THIS AFTERNOON.
OTHERWISE, LITTLE CHANGE TO THE GOING FORECAST.
THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY
IN A ZONAL FLOW AS A TROUGH MOVES ACROSS THE GREAT LAKES. AT THE
SURFACE, A 1000MB LOW IS LOCATED NORTH OF MICHIGAN. A COLD FRONT
EXTENDS SOUTHWEST OF THIS FEATURE ACROSS MICHIGAN AND INTO
INDIANA. AHEAD OF THE FRONT, AN AREA OF LIGHT SNOW IS PUSHING INTO THE
NORTHWEST HALF OF OHIO. THE SNOW INCREASES IN INTENSITY CLOSER TO
THE FRONT, WITH MODERATE SNOW REPORTED WITH SEVERAL OBS UPSTREAM
IN INDIANA.
THIS AFTERNOON...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST
TOWARD THE AREA, WITH THE RUC/HRRR WIND SHIFT SUPPORTING THE FRONT
REACHING A ZANESVILLE-NEW PHILADELPHIA-FRANKLIN LINE BY 00Z THIS
EVENING. FORECAST CONSISTS OF A BLEND OF THE HRRR/NAM4KM, WITH
LIGHT SNOW REACHING AREAS NORTH AND WEST OF PITTSBURGH BY 19Z WITH
LIKELY POPS REACHING THE EASTERN RIDGES OF MD/WV BY 23Z. SNOW WILL
INCREASE IN INTENSITY AT TIMES, REDUCING VISIBILITIES THIS
EVENING. A FACTOR IN THE SNOWFALL ACCUMULATION AT LEAST INITIALLY
WILL BE SURFACE TEMPS, WITH AREAS SOUTH OF I-70 WARMING INTO THE
MID TO UPPER 30S. THIS WILL LIMIT SNOWFALL ACCUMULATION THERE
INITIALLY. THUS FORECAST INTO THE EARLY EVENING IS FOR AROUND AN
INCH NORTH OF I-70 AND FOR A HALF OF AN INCH OR LESS SOUTHWARD.
FOR TEMPS, FORECAST IS A FEW DEGREES WARMER THAN A LAMP/HRRR BLEND,
WITH HIGHS RANGING FROM THE UPPER 30S ACROSS NORTH-CENTRAL WV TO
NEAR 30 ALONG THE I-80 CORRIDOR.
TONIGHT...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST ACROSS THE
UPPER OHIO VALLEY, PUSHING SOUTHEAST OF THE RIDGES BY 03Z FRI.
THE BEST CHANCE FOR SNOW ACCUMULATION AND POTENTIALLY HAZARDOUS
TRAVEL WILL BE AFTER SUNSET THROUGH MIDNIGHT AS SNOW PUSHES ACROSS
THE AREA. SNOW WILL BEGIN TO TAPER OFF BEHIND THE FRONT WITH JUST
A FEW LINGERING SNOW SHOWERS ALONG THE I-80 CORRIDOR AND EASTERN
RIDGES BY DAWN. MOSTLY AROUND AN ADDITIONAL INCH OF SNOWFALL WILL BE
POSSIBLE TONIGHT, WITH 1 TO 3 POSSIBLE IN LOCALIZED AREAS AND THE
EASTERN RIDGES. STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT
WILL ALLOW FOR LOWS RANGING FROM NEAR 20 ACROSS NORTH-CENTRAL WV TO
THE MID TO UPPER TEENS ELSEWHERE.
TOTAL SNOWFALL FOR THIS AFTERNOON THROUGH TONIGHT WILL GENERALLY
BE 1 TO 2 INCHES ACROSS MUCH OF THE AREA. LOCALIZED AREAS OF UP
TO 3 INCHES WILL BE POSSIBLE NORTH OF THE PITTSBURGH METRO AND
ACROSS THE EASTERN RIDGES WITH COOLER TEMPS AT THE ONSET OF THE
SNOW. IN ADDITION, AREAS SOUTH OF I-70 WILL SEE AROUND AN INCH.
ALTHOUGH SNOW AMOUNTS FORECAST ARE MOSTLY SUB-ADVISORY AMOUNTS,
WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS NORTH OF
PITTSBURGH DUE TO TIMING OF THE SNOW IMPACTING THE EVENING
COMMUTE.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY/...
MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE
FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST
DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE
PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST
IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND
FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE
OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF
PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR
THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK
FOR THESE POTENTIALS.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE
DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY.
AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW
ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE
ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO
CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW.
DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH
MOVES EASTWARD INTO THE OHIO VALLEY.
STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE
NORMAL THROUGH THE EXTENDED PERIOD.
&&
.AVIATION /16Z THURSDAY THROUGH MONDAY/...
VFR FORECAST INTO THE AFTERNOON. AFTER DAWN, THERE WILL BE IN AN
INCREASE IN MID DECK CLOUD COVER AS WELL AS STRENGTHENING SW SFC
WINDS, WITH SOME GUSTS TO 20 KTS BY MIDDAY.
COLD FRONT WILL REACH THE WESTERN EDGE OF THE AREA AROUND 20Z. MVFR
TO IFR RESTRICTIONS WITH SNOW AND LOW CLOUDS EXPECTED AT ALL
PORTS DURING THE AFTERNOON AND EVENING HOURS.
OUTLOOK...TONIGHT NIGHT THROUGH MONDAY...
RESTRICTIONS WITH SNOW AND LOW CLOUDS WILL CONTINUE THROUGH THIS
EVENING. VIS SHOULD QUICKLY IMPROVE AFTER 06Z AS AREA OF SNOW
SHOWERS MOVES SOUTHEAST.
VFR CONDITIONS WILL BRIEFLY RETURN FRIDAY AS A SURFACE HIGH SLIDES
ACROSS THE REGION. A SYSTEM TRACKING SOUTH OF THE AREA WILL BRING A
WINTRY MIX WITH RESTRICTIONS FRIDAY NIGHT AND SATURDAY. AFTER A
PERIOD OF VFR WEATHER SUNDAY, AN APPROACHING FRONT IS PROGGED TO
SPREAD SCATTERED RAIN SHOWERS AND RESTRICTIONS ACROSS THE TERMINALS
MONDAY.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
OH...NONE.
PA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR
PAZ007>009-013>016-022-023.
WV...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1249 PM CST THU JAN 19 2012
.UPDATE...
ARCTIC HIGH PRESSURE CONTINUES TO DOMINATE THE REGION. TEMPS HAVE
BEEN SLOW TO RISE THIS MORNING...AND HAVE DROPPED HIGHS AND
HOURLY TEMPS FOR TODAY. FOLLOWED CLOSE TO RUC GUIDANCE...WHICH
HAS THE BEST CURRENT POSITION BASED ON LATEST OBS.
&&
.AVIATION...
VFR CONDITIONS TODAY AS ARCTIC HIGH PRESSURE DOMINATES THE
PLAINS. WARM AIR WILL LIFT NORTHEAST AS CENTER OF HIGH SLIDES TO
THE SOUTHEAST OVERNIGHT. MODELS INCREASE LL RH VALUES LATE
TONIGHT...WITH MOS GUIDANCE SHOWING MVFR/IFR CIGS DEVELOPING OVER
NORTHERN AND CENTRAL NEBRASKA. HIGHER CONFIDENCE WILL SEE AN
IMPACT AT KVTN...HOWEVER MODELS ARE FASTER THAT ACTUALLY
HAPPENING WITH RETREATING THE COLD AIR. THIS MAY RESULT IN
STRATUS IMPACTING PARTS OF SW NEBRASKA...AND THE KLBF TERMINAL.
WILL MONITOR FOR POSSIBLE ADDITION TO LBF TAF. ANY STRATUS THAT
DOES DEVELOP WILL BE SLOW TO LIFT TOMORROW MORNING AND EARLY
AFTERNOON.
&&
.PREV DISCUSSION.../ISSUED 341 AM CST THU JAN 19 2012/
SYNOPSIS... HAND ANALYSIS OF THE 19.00Z H25 AND H5 LEVELS REVEALS
NORTHWESTERLY FLOW ACROSS THE NORTHERN AND CENTRAL HIGH
PLAINS...WITH STRONG UPPER LEVEL JET SUPPORT OF GREATER THAN 150
KTS EDGING FROM THE EASTERN CASCADES TOWARD THE BLACK HILLS REGION
OF SOUTH DAKOTA. A SHORTWAVE TROUGH WAS ANALYZED IN THE MID LEVELS
NEAR LAKE SUPERIOR...WITH ANOTHER WAVE CLOSING IN ON THE PACIFIC
NORTHWEST. AT THE SURFACE...COLD ARCTIC AIR HAS ONCE AGAIN
FILTERED ACROSS THE SAND HILLS REGION OF NEBRASKA...WITH SUB ZERO
TEMPERATURES ALONG THE NIOBRARA RIVER VALLEY EARLY THIS MORNING.
FURTHER SOUTH...SINGLE DIGIT READINGS ARE THE NORM. REGIONAL
RADARS ARE INTERROGATING A BAND OF LIGHT SNOW ACROSS WESTERN SOUTH
DAKOTA...BUT GENERALLY VOID OF PRECIPITATION ELSEWHERE.
DISCUSSION...
ANOTHER TRICKY TEMPERATURE FORECAST IS IN STORE FOR THIS AFTERNOON
AS THE ARCTIC FRONT RETREATS NORTH AND EAST...AND SOUTHERLY FLOW
RETURNS OVER SOUTHERN AND WESTERN NEBRASKA. THE MODELS INDICATE
WARMING ALOFT...AS THE CONSENSUS SUGGESTS H85 TEMPERATURES GENERALLY
RANGING FROM 8C ACROSS SOUTHWEST NEBRASKA TO -8C OVER NORTH CENTRAL
NEBRASKA BY 00Z FRIDAY. HOWEVER CLOSER TO THE SURFACE...H925
TEMPERATURES REMAIN BELOW 0C ACROSS MUCH OF THE CWA THROUGH 00Z
FRIDAY...WITH -2 AT LBF AND -12C AT ONL. THE 00Z UNR SOUNDING
INDICATES ABOUT 2-3K FT DEPTH OF THE COLDER AIR...SO ITS GONNA TAKE
SOME MIXING TO SCOUR OUT THE LAYER...BUT UNFORTUNATELY WITH SOUTH TO
SOUTHEASTERLY FLOW...MIXING WILL BE RATHER LIMITED TODAY. SO ONLY
THE FAR WESTERN PORTIONS OF THE CWA MAY SEE TEMPERATURES ABOVE 0C
THIS AFTERNOON...ELSEWHERE TEMPERATURES WILL RANGE FROM THE LOW
TEENS OVER NORTH CENTRAL NEBRASKA TO THE LOW 30S AT LBF. FOR
TONIGHT...AGAIN WARMING ALOFT WILL OCCUR...BUT WITH THE SHALLOW
ARCTIC AIR MASS IN PLACE...STILL LOOKING FOR BELOW AVERAGE LOWS OVER
MUCH OF THE CWA...WITH LOWS RANGING FROM THE SINGLE DIGITS ACROSS
NORTH CENTRAL NEBRASKA...TO POSSIBLY LOW TO MID 20S ACROSS SOUTHWEST
NEBRASKA. MODELS CONTINUE TO INDICATE A CHANCE OF PRECIPITATION
ALONG NORTHERN NEBRASKA OVERNIGHT TONIGHT AS WELL. BEST FORCING AND
SUPPORT FOR THE PRECIPITATION HAS TRENDED NORTH INTO SOUTH DAKOTA
THE PAST COUPLE MODEL RUNS...WITH FAVORABLE SATURATION PRESSURE
DEFICITS NORTH OF THE CWA. BUT FAVORABLE UPPER LEVEL JET SUPPORT
WILL BE IN THE REGION...AND MODEL SOUNDINGS INDICATE SUFFICIENT
SATURATION OVER NORTHERN NEBRASKA...SO NOT READY TO PULL THE PLUG ON
PRECIPITATION CHANCES YET. WILL LEAVE POPS AT CHANCE TO LOW END
LIKELY ACROSS NORTH CENTRAL NEBRASKA FOR NOW...BUT QPF AMOUNTS LOOK
LIGHT AT BEST. MODEL SOUNDINGS ALSO INDICATE THE POTENTIAL FOR A
MIXED BAG OF PRECIPITATION...WITH POSSIBLY SOME IP OR ZR AS WAA
PUSHES TEMPERATURES ALOFT ABOVE 0C ACROSS NORTHERN NEBRASKA...THIS
WILL NEED TO BE RE-EVALUATED WITH THE NEWEST MODEL GUIDANCE AND FOR
NOW WILL LEAVE AS -SN AS TEMPERATURE CONFIDENCE IS LOW. ARCTIC
FRONT PLUNGES SOUTH ONCE AGAIN ON FRIDAY...AND AGAIN A DIFFICULT
HIGH TEMPERATURE FORECAST IS IN STORE. WHAT IS CERTAIN IS NORTHERN
NEBRASKA WILL BE BELOW AVERAGE...WITH HIGHS IN THE TEENS...SOUTH OF
INTERSTATE 80...AND OVER THE HIGHER TERRAIN OF THE WEST...40S MAY BE
POSSIBLE. THE ARCTIC AIR MASS MODIFIES AND BUILDS EAST AGAIN ON
SATURDAY...AS SOUTHERLY FLOW RETURNS TO THE PLAINS. H925
TEMPERATURES BY LATE SATURDAY AFTERNOON SHOULD PUSH WELL ABOVE 0C
FOR MUCH OF THE CWA...WITH THE EXCEPTION OF OUR FAR EASTERN
ZONES...SO HIGHS SHOULD RANGE FROM THE LOW 30S OVER THE EAST...TO
NEAR 50 ACROSS THE FAR WEST. SUNDAY MAY BE INTERESTING...THE MODELS
HAVE BEEN ADVERTISING A RAPIDLY ADVANCING MID TO UPPER TROUGH
PASSAGE OVER THE LAST FEW RUNS. THE EUROPEAN SOLUTION THIS EVENING
IS NOW INDICATING A DEEPER AND POTENTIALLY MORE SIGNIFICANT PASSAGE
FOR THE CWA. THIS NEW SOLUTION WOULD GIVE THE CWA WIDESPREAD
ACCUMULATING QPF...NOT SIGNIFICANT AMOUNTS...BUT WITH THE DRY WINTER
THUS FAR...ANY ACCUMULATIONS WOULD BE APPRECIATED. GFS AND NAM
CONTINUE TO TARGET NORTH OF THE CWA. THE EURO PRECIP FIELD MAY BE
OVERDONE...BUT WORTHY OF AT LEAST A SLIGHT CHANCE MENTION FOR NOW.
AS FOR PTYPE...TEMPERATURES AT THIS POINT IN TIME LOOK TO BE WARM
ENOUGH FOR ALL RAIN OVER MUCH OF THE CWA...BUT GIVEN IT/S
JANUARY...WILL GO WITH RAIN OR SNOW FOR NOW. FOR THE START IF THE
WORK WEEK...SLIGHTLY WARMER AIR SHOULD RETURN EARLY NEXT WEEK WITH
HIGHS AT OR SLIGHTLY ABOVE CLIMO. ANOTHER QUICK MOVING TROUGH WILL
CROSS THE NORTHERN PLAINS ON TUESDAY...BRINGING ANOTHER
SHOT...ALBEIT SLIGHT CHANCE AT THIS POINT IN TIME...OF
PRECIPITATION...MADE ON MINOR ADJUSTMENTS TO THE EXTENDED BEYOND
SUNDAY AFTERNOON.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
UPDATE/AVIATION...MASEK
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1123 AM CST THU JAN 19 2012
.AVIATION...18Z TAF. ARCTIC HIGH PRESSURE WILL SLIDE TO THE EAST
TODAY INTO TONIGHT. THIS WILL ALLOW RETURN FLOW...AND WARMER AIR
TO RETURN TO THE AREA. AS THE WARMER AIR RETURNS...THERE ARE SOME
SIGNS STRATUS COULD TRY TO DEVELOP OVERNIGHT...BUT THE 12Z NAM IS
NOW SLOWER IN BRINGING THE LOW CLOUDS TO KGRI. IN FACT...IT GENERALLY
SUGGESTS THAT MID AND HIGH LEVEL CLOUDS WILL DOMINATE UNDER THE
H85 WARM AIR ADVECTION...HOWEVER ONCE THE ARCTIC AIR MOVES SOUTH
AGAIN ON FRIDAY...STRATUS COULD COME WITH IT. WILL HOLD ONTO A VFR
FORECAST THROUGH TONIGHT...BUT WILL CARRY SCATTERED CLOUDS AROUND
2500FT IN ORDER TO SUGGEST THERE IS SOME CHANCE LOWER CLOUDS COULD
TRY TO DEVELOP OVERNIGHT. WILL GO WITH AN MVFR CEILING LATE IN THE
PERIOD...WHICH IS IN LINE WITH THE NAM...AS THE ARCTIC AIR AGAIN
INVADES THE AREA. WINDS WILL START OUT LIGHT AND VARIABLE...BUT
SHOULD TURN SOUTHERLY THIS AFTERNOON AS THE HIGH SLIDES EAST.
WINDS WILL BECOME NORTHERLY AGAIN LATE IN THE PERIOD AS ANOTHER
COLD FRONT DROPS SOUTH ACROSS THE TERMINAL LOCATION.
&&
.PREV DISCUSSION... /ISSUED 1027 AM CST THU JAN 19 2012/
UPDATE...SENT A QUICK UPDATE TO ADJUST THE HOURLY TEMPERATURE
CURVE TO BETTER REFLECT REALITY...OTHERWISE THE REMAINDER OF THE
FORECAST LOOKS ON TRACK FOR TODAY.
PREV DISCUSSION... /ISSUED 639 AM CST THU JAN 19 2012/
UPDATE...JUST RAN A QUICK UPDATE TO TABULAR AFM/PFM PRODUCTS AND
WEB-BASED PRODUCTS TO BRING NEXT SEVERAL HOURS OF TEMP/DEWPOINT
TRENDS MORE IN LINE WITH CURRENT OBS...AS COLDER AND DRIER AIR HAS
PUSHED MORE AGGRESSIVELY SOUTHWARD INTO SOUTHERN PORTIONS OF THE
CWA THAN EXPECTED EVEN A FEW HOURS AGO. ONLY MODEL/GUIDANCE REALLY
PROVING USEFUL FOR THESE VERY SHORT TERM TRENDS IS GFS LAMP
GUIDANCE. WIND CHILLS BETWEEN -10 AND -15 WILL BE WIDESPREAD
ACROSS MOST ALL NEB ZONES FOR THE NEXT FEW HOURS...WITH KS ZONES
MORE SO -5 TO -10. ALTHOUGH NO CHANGES WERE MADE TO AFTERNOON HIGH
TEMPS AT THIS TIME...INTERESTING TO NOTE THAT BOTH THE 09Z RUC AND
HRRR SUGGEST THAT THE TRI-CITIES WILL RECOVER ENOUGH TO POSSIBLY
REACH 20 THIS AFTERNOON...BUT THIS SEEMS TOO OPTIMISTIC AT THIS
TIME AND WILL STICK WITH GOING FORECAST.
PREV DISCUSSION... /ISSUED 451 AM CST THU JAN 19 2012/
SHORT TERM...THROUGH SATURDAY NIGHT. PRIMARY CONCERN DURING THE
NEXT 72 HOURS CONTINUES TO BE TEMPERATURE TRENDS...WITH THE NEXT
REGIONAL SNOW EVENT FROM THURSDAY NIGHT INTO FRIDAY STILL PROGGED
TO MISS MOST...IF NOT ALL OF THE CWA TO THE NORTHEAST...FOCUSING
ALONG AN AXIS FROM SD THROUGH NORTHEAST NEB/NORTHERN IA. THAT
BEING SAID...ALTHOUGH NOT OVERLY CONCERNED AT THIS POINT...WILL
NEED TO MONITOR LOW LEVEL MOISTURE TRENDS CLOSELY LATE THURS NIGHT
INTO FRIDAY MORNING TO MAKE SURE THAT NO LIGHT FREEZING DRIZZLE
TRIES TO SNEAK UP ON US.
09Z OBJECTIVE SURFACE ANALYSIS REVEALS THAT THE WELL ADVERTISED
ARCTIC COLD FRONT HAS MADE STEADY PROGRESS SOUTHWARD ACROSS THE
CWA THROUGH THE NIGHT...PUSHED ALONG BY A BROAD 1024MB HIGH
CENTERED FROM MT TO NORTHERN SD. TEMPERATURES AT 09Z RANGED FROM 2
AT ORD...TO 18 AT BELOIT. ADDING TO THE INVADING BITTERNESS ARE
STEADY NORTH-NORTHEAST BREEZES OF 10-20 MPH...YIELDING WIND CHILL
VALUES RANGING FROM -10 TO -15 NORTH OF I-80...TO NEAR ZERO IN THE
SOUTH. DESPITE PLENTIFUL MID LEVEL RADAR RETURNS EARLIER THE NIGHT
ACROSS THE NORTHEAST...IT IS LIKELY THAT FLURRY ACTIVITY DID NOT
MATERIALIZE ACROSS THE NORTHEAST. ALOFT...WATER VAPOR IMAGERY AND
SHORT TERM MODEL DATA FEATURE VERY FAST NORTHWEST FLOW BISECTING
THE CONUS FROM NORTHWEST TO SOUTHEAST...HIGHLIGHTED BY A 140+KT
300MB JET STREAK CUTTING ACROSS EASTERN NEB. ALTHOUGH THE PRIMARY
MID LEVEL SHORTWAVE/500MB VORT MAX OF NOTE IS ALREADY WELL
NORTHEAST INTO THE GREAT LAKES...LIFT ASSOCIATED WITH THE UPPER
JET STREAK HAS GENERATED PLENTIFUL CIRRUS OVER MAINLY NEB ZONES
OVERNIGHT...BUT KEEPING PRIMARY ZONE OF MID LEVEL
SATURATION/POSSIBLE LIGHT SNOW PRODUCTION OFF TO THE NORTH AND
EAST.
TODAY...THE AFOREMENTIONED STRONG UPPER JET AXIS DRIFTS
NORTHEAST...WITH ITS CENTER ALONG AN AXIS FROM CENTRAL ND TO
NORTHERN IL BY 00Z THIS EVENING. AS A RESULT...THE EXTENSIVE HIGH
LEVEL CLOUD COVER ACROSS MOST OF THE CWA SHOULD GRADUALLY SCATTER
OUT AND/OR LIFT NORTHEAST AS WELL...WITH AT LEAST PARTLY CLOUDY
SKIES ANTICIPATED MOST AREAS FOR THIS AFTERNOON. EVEN IF THE SUN
IS OUT...IT WON/T DO A WHOLE LOT TO MASK WHAT IS ALMOST CERTAINLY
TO BE THE OVERALL COLDEST DAY OF THE WINTER SO FAR FOR MOST OF THE
CWA. AS THE DAY WEARS ON...THE CENTER OF THE SURFACE HIGH WILL
MIGRATE INTO MN/IA...ALLOWING BREEZES TO GRADUALLY DIMINISH INTO
THE 5-10 MPH RANGE FOR THIS AFTERNOON AS THEY GRADUALLY SHIFT FROM
MORE NORTHERLY TO MORE EASTERLY/SOUTHEASTERLY BY LATE IN THE DAY.
AS FOR TEMPS...YET AGAIN OPTED TO LOWER HIGHS BY 2-5 DEGREES FROM
PREVIOUS FORECAST IN MOST AREAS...LEANING TOWARD THE COLDER MAV
GUIDANCE. THIS YIELDS HIGHS RANGING FROM ONLY 10-13 DEGREES IN THE
NORTHEAST CWA...TO MID 20S FAR SOUTH AND WEST WHERE THE SOUTHEAST
FLOW AROUND THE HIGH SHOULD HELP MODERATE THINGS SOMEWHAT. AS FOR
WIND CHILLS THIS MORNING...VALUES WILL CONTINUE TO RANGE BETWEEN
-10 AND -17 ACROSS MUCH OF THE NORTHEAST 1/2 OF THE CWA THROUGH AT
LEAST MID-MORNING...WHICH WILL BE ABOVE ADVISORY CRITERIA OF -20
BUT NOT BY MUCH. ITS CLOSE ENOUGH THAT WILL PUT A MENTION IN THE
HAZARDOUS WEATHER OUTLOOK.
TONIGHT...THE NEXT BATCH OF BROAD...LOW AMPLITUDE SHORTWAVE ENERGY
QUICKLY APPROACHES THE CENTRAL CONUS FROM THE NORTHWEST. WITHIN
THE ENTRANCE REGION OF THE PRIMARY UPPER JET AXIS MIGRATING ACROSS
THE UPPER MISS VALLEY/GREAT LAKES...AN IMPRESSIVE ZONE OF
ISENTROPIC LIFT/MID LEVEL CONVERGENCE WILL SET UP ALONG AND NORTH OF
THE PRIMARY LOW-MID LEVEL TEMPERATURE GRADIENT CENTERED FROM SD
INTO NORTHEAST NEB/IA. THIS WILL BE THE OBVIOUS FOCUS FOR THE
START OF A MEASURABLE SNOW EVENT FOR THOSE AREAS. ALTHOUGH IT IS
SEEMING MORE AND MORE LIKELY THAT THE CWA WILL MISS OUT ON THIS
ACTION...PREVIOUS FORECAST HAD SOME LOW POPS ACROSS THE
NORTHEAST...AND WILL CONTINUE THIS MENTION AFTER MIDNIGHT FOR
MAINLY THE NORTHEAST 1/5 OF THE CWA JUST IN CASE THE FAR SOUTHERN
EDGE OF THIS ACTIVITY SLIPS IN. ANY ACCUMULATIONS...IF ANY...WOULD
NOT AMOUNT TO MORE THAN A FEW TENTHS. INTERESTINGLY...IF ANYTHING
DOES HAPPEN TO FALL IN THE FAR NORTH TONIGHT...IT MIGHT ACTUALLY
FAVOR THE FORM OF LIGHT SLEET BASED ON FORECAST SOUNDINGS...BUT
WILL LEAVE IT AS SNOW MENTION FOR NOW. HAVE ALSO BEEN GROWING A
BIT LEARY OF POSSIBLE LIGHT FREEZING DRIZZLE ACROSS NORTHERN
PORTIONS OF THE AREA GIVEN THE GOOD LOW LEVEL WARM ADVECTION...BUT
THINKING AT THIS POINT IS THAT ANY POTENTIAL STRATUS LAYER WOULD
BE TOO SHALLOW TO SUPPORT THIS. SOMETHING TO WATCH. AS FOR LOW
TEMPS...CHANGED THEM LITTLE...ALTHOUGH CONFIDENCE IN HOURLY TRENDS
IS QUITE LOW AS TEMPS COULD EASILY DISPLAY STEADY/SLOWLY RISING
CHARACTERISTICS AS BREEZES TURN SOUTHERLY. KEPT IT SIMPLE FOR NOW
THOUGH...INDICATING MOST AREAS BOTTOMING OUT BETWEEN 9 AND 15
DEGREES...ALTHOUGH THIS MIGHT END UP BEING EARLIER IN THE NIGHT
VERSUS LATER FOR SOME PLACES.
FRIDAY...THE MAIN BATCH OF SHORTWAVE ENERGY PASSES THROUGH THE
CENTRAL PLAINS...ALTHOUGH THE UPPER JET FORCING CONTINUES TO
DIRECT THE MAIN PRECIP EVENT FROM EASTERN SD INTO NORTHERN
IA/SOUTHERN MN AND POINTS EAST. THUS LEFT PRECIP MENTION OUT OF
THE FORECAST...ALTHOUGH ONCE AGAIN WILL HAVE TO MONITOR DEPTH OF
POSSIBLE STRATUS LAYER CLOSELY FOR OUTSIDE CHANCE OF SNEAKY LIGHT
FREEZING DRIZZLE THREAT...BUT JUST SEEMS RATHER UNLIKELY AT THIS
JUNCTURE. AS FOR HIGH TEMPS...THE SOUTHERN EDGE OF THE ARCTIC COLD
FRONT WILL PLAY A BIG ROLE AS IT IS PROGGED TO DROP RIGHT BACK
SOUTH ACROSS THE CWA OVER THE COURSE OF THE DAY...ALTHOUGH THE GFS
IS MUCH MORE AGGRESSIVE THAN THE LATEST ECMWF/NAM REGARDING WITH
THIS COLD PUSH. CONSENSUS OF SEVERAL MODELS/GUIDANCE WAS TO...YOU
GUESSED IT...LOWER TEMPS SEVERAL DEGREES...AND BUMPED DOWN 3-5
DEGREES MOST AREAS...NOW ADVERTISING MID 20S NORTHEAST TO UPPER
30S SOUTHWEST. INTERESTING TO NOTE THAT THIS DAY HAS NOW TRENDED
15+ DEGREES COLDER THAN FORECASTS ISSUED JUST 2-3 DAYS AGO.
FRIDAY NIGHT...IT REMAINS DRY AS A SURFACE RIDGE AXIS SLIDES
ACROSS THE CENTRAL PLAINS...AND A BRIEF BIT OF SHORTWAVE RIDGING
SETS IN ALOFT. ASSUMING LIMITED CLOUD COVER...TEMPS COULD TAKE A
DECENT TUMBLE...AND LOWERED LOWS 5 DEGREES MOST AREAS WITH SINGLE
DIGITS ABOVE ZERO NOW IN PLACE FOR MUCH OF THE CWA.
SATURDAY...THE NEXT...MORE VIGOROUS MID LEVEL WAVE STARTS MAKING
ITS WAY ACROSS THE CENTRAL/SOUTHERN ROCKIES...INDUCING SURFACE
PRESSURE FALLS AND RAMPING UP SOUTH-SOUTHEAST BREEZES INTO AT
LEAST THE 15-20 MPH SUSTAINED RANGE. DESPITE THIS SOUTHERLY
WIND...THE DIRECTION IS NOT OVERLY CONDUCIVE FOR SIGNIFICANT
WARMING...AND HAVE ONLY INDICATED A MODEST WARM-UP OVER
FRIDAY...WITH HIGHS RANGING FROM LOW 30S FAR EAST TO LOW 40S FAR
WEST.
SATURDAY NIGHT...LEFT THIS PERIOD DRY...AT LEAST FOR NOW...AS THE
INCOMING SHORTWAVE CONTINUES TO AMPLIFY/STRENGTHEN AS A 100+KT
UPPER JET STARTS TO ROUND THE BASE INTO THE CENTRAL PLAINS. ONLY
THING KEEPING POPS FROM BEING INSERTED AT THIS POINT IS SUGGESTION
THAT A MID LEVEL DRY SLOT WILL BE IN PLACE ACROSS THE CWA...WITH
MAIN FORCING/MID LEVEL DEFORMATION AXIS HOLDING JUST OFF TO THE
NORTH/WEST...THUS HOLDING OFF BETTER PRECIP CHANCES UNTIL SUNDAY
AS DISCUSSED BELOW.
LONG TERM...SUNDAY THROUGH WEDNESDAY. PATTERN REMAINS
PROGRESSIVE THROUGH THE EXTENDED PERIODS WITH CHALLENGE OF TRYING
TO TIME WAVES. BEGINNING ON SUNDAY...A 100+KT JET NOSES EAST FM
THE FOUR CORNERS REGION AND LIFTS NORTHEAST ACROSS THE CENTRAL
PLAINS DEEPENING THE MID/UPPER TROUGH ACROSS THE CENTRAL PLAINS.
THE 00Z ECMWF IS THE STRONGEST/SLOWEST WITH THE SYSTEM ON SUNDAY
AND CLOSES OFF THE H7 LOW...WHEREAS OTHER EXTENDED MODELS SUGGEST
A MORE PROGRESSIVE OPEN WAVE. IN GENERAL...THERE IS CONSENSUS
AMONG MODELS THAT OUR REGION WILL BE UNDER THE INFLUENCE OF A
TROUGH THRU AT LEAST THE FIRST HALF OF THE DAY...OR LONGER IF
SLOWER ECWMF VERIFIES. COOL FRONTAL BOUNDARY WILL SWEEP ACROSS OUR
REGION IN MORNING WITH AN AREA OF LOW CLOUDS/PCPN ACCOMPANYING
SYSTEM AIDED BY ENHANCED UPPER DYNAMICS IN LFQ OF JET. HOW LONG
PCPN/LOW CLOUDS LINGERS IS DEPENDENT ON STRENGTH OF SYSTEM AND IF
SYSTEM MOVES THRU FASTER...CLEARING SKIES/DOWNSLOPE CONDITIONS MAY
AID IN SOME WARMING FOR THE AFTN. IN ADDITION TO THE PCPN
POTENTIAL...MODELS ALSO SUGGEST STRONG WIND POTENTIAL SUNDAY WITH
NAM INDICATING 3HR PRESSURE RISES OF 6MB BEHIND THE FRONT IN
TIGHTENING SFC GRADIENT...WHILE A CORRIDOR OF 50 TO 60KT MID
LEVEL WINDS CROSS OUR REGION. WILL NEED TO MONITOR MODEL TRENDS OF
THIS AS WELL. FOR PCPN TYPE ON SUNDAY...HAVE WENT WITH R/S IN THE
MORNING TRANSITIONING TO RAIN IN AFTN AS TEMPS LOOK TO RISE ABOVE
FREEZING.
HEADING INTO SUNDAY NIGHT...THE TROUGH AXIS DEPARTS AND CONDITIONS
DRY WITH RISING HEIGHTS BEHIND THE EXITING SYSTEM. MODELS ARE STILL
LOOKING DRY MONDAY IN BETWEEN SYSTEMS...AND THEN NEXT WAVE IS PROGGED
TO EMERGE ONTO THE PLAINS ON TUESDAY. THERE IS STILL SOME
UNCERTAINTY ON DEGREE OF MOISTURE WITH THIS NEXT SYSTEM BUT SMALL
CHCS FOR PCPN STILL WARRANTED AS CURRENTLY FORECAST. MILD AIRMASS IN PLACE
SHLD MAINTAIN LIQUID CHCS INITIALLY WITH POTENTIAL FOR CHANGE TO
SNOW IN COOLER AIR WITH FROPA TUESDAY NIGHT.
THE AIRMASS IN GENERAL DURING THE EXTENDED IS NOT OVERLY COLD AND
TEMPS LOOK TO BE MORE DEPENDENT ON CLOUDS/PCPN.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1027 AM CST THU JAN 19 2012
.UPDATE...SENT A QUICK UPDATE TO ADJUST THE HOURLY TEMPERATURE
CURVE TO BETTER REFLECT REALITY...OTHERWISE THE REMAINDER OF THE
FORECAST LOOKS ON TRACK FOR TODAY.
&&
.PREV DISCUSSION... /ISSUED 639 AM CST THU JAN 19 2012/
UPDATE...JUST RAN A QUICK UPDATE TO TABULAR AFM/PFM PRODUCTS AND
WEB-BASED PRODUCTS TO BRING NEXT SEVERAL HOURS OF TEMP/DEWPOINT
TRENDS MORE IN LINE WITH CURRENT OBS...AS COLDER AND DRIER AIR HAS
PUSHED MORE AGGRESSIVELY SOUTHWARD INTO SOUTHERN PORTIONS OF THE
CWA THAN EXPECTED EVEN A FEW HOURS AGO. ONLY MODEL/GUIDANCE REALLY
PROVING USEFUL FOR THESE VERY SHORT TERM TRENDS IS GFS LAMP
GUIDANCE. WIND CHILLS BETWEEN -10 AND -15 WILL BE WIDESPREAD
ACROSS MOST ALL NEB ZONES FOR THE NEXT FEW HOURS...WITH KS ZONES
MORE SO -5 TO -10. ALTHOUGH NO CHANGES WERE MADE TO AFTERNOON HIGH
TEMPS AT THIS TIME...INTERESTING TO NOTE THAT BOTH THE 09Z RUC AND
HRRR SUGGEST THAT THE TRI-CITIES WILL RECOVER ENOUGH TO POSSIBLY
REACH 20 THIS AFTERNOON...BUT THIS SEEMS TOO OPTIMISTIC AT THIS
TIME AND WILL STICK WITH GOING FORECAST.
PREV DISCUSSION... /ISSUED 600 AM CST THU JAN 19 2012/
AVIATION...12Z TAF. ARCTIC HIGH PRESSURE WILL SHIFT INTO NORTHERN
IOWA TODAY. NORTHEASTERLY WINDS THIS MORNING WILL BECOME VARIABLE
FOR A FEW HOURS AROUND MIDDAY BEFORE TRANSITIONING TO THE
SOUTHEAST. CLOUD COVER LOOKS TO BE LIMITED TO THE MID AND HIGH
LEVELS FOR MUCH OF THE DAY WITH SOME MVFR TO VFR CIGS POSSIBLE
LATER TONIGHT OR TOWARD FRIDAY MORNING.
PREV DISCUSSION... /ISSUED 451 AM CST THU JAN 19 2012/
SHORT TERM...THROUGH SATURDAY NIGHT. PRIMARY CONCERN DURING THE
NEXT 72 HOURS CONTINUES TO BE TEMPERATURE TRENDS...WITH THE NEXT
REGIONAL SNOW EVENT FROM THURSDAY NIGHT INTO FRIDAY STILL PROGGED
TO MISS MOST...IF NOT ALL OF THE CWA TO THE NORTHEAST...FOCUSING
ALONG AN AXIS FROM SD THROUGH NORTHEAST NEB/NORTHERN IA. THAT
BEING SAID...ALTHOUGH NOT OVERLY CONCERNED AT THIS POINT...WILL
NEED TO MONITOR LOW LEVEL MOISTURE TRENDS CLOSELY LATE THURS NIGHT
INTO FRIDAY MORNING TO MAKE SURE THAT NO LIGHT FREEZING DRIZZLE
TRIES TO SNEAK UP ON US.
09Z OBJECTIVE SURFACE ANALYSIS REVEALS THAT THE WELL ADVERTISED
ARCTIC COLD FRONT HAS MADE STEADY PROGRESS SOUTHWARD ACROSS THE
CWA THROUGH THE NIGHT...PUSHED ALONG BY A BROAD 1024MB HIGH
CENTERED FROM MT TO NORTHERN SD. TEMPERATURES AT 09Z RANGED FROM 2
AT ORD...TO 18 AT BELOIT. ADDING TO THE INVADING BITTERNESS ARE
STEADY NORTH-NORTHEAST BREEZES OF 10-20 MPH...YIELDING WIND CHILL
VALUES RANGING FROM -10 TO -15 NORTH OF I-80...TO NEAR ZERO IN THE
SOUTH. DESPITE PLENTIFUL MID LEVEL RADAR RETURNS EARLIER THE NIGHT
ACROSS THE NORTHEAST...IT IS LIKELY THAT FLURRY ACTIVITY DID NOT
MATERIALIZE ACROSS THE NORTHEAST. ALOFT...WATER VAPOR IMAGERY AND
SHORT TERM MODEL DATA FEATURE VERY FAST NORTHWEST FLOW BISECTING
THE CONUS FROM NORTHWEST TO SOUTHEAST...HIGHLIGHTED BY A 140+KT
300MB JET STREAK CUTTING ACROSS EASTERN NEB. ALTHOUGH THE PRIMARY
MID LEVEL SHORTWAVE/500MB VORT MAX OF NOTE IS ALREADY WELL
NORTHEAST INTO THE GREAT LAKES...LIFT ASSOCIATED WITH THE UPPER
JET STREAK HAS GENERATED PLENTIFUL CIRRUS OVER MAINLY NEB ZONES
OVERNIGHT...BUT KEEPING PRIMARY ZONE OF MID LEVEL
SATURATION/POSSIBLE LIGHT SNOW PRODUCTION OFF TO THE NORTH AND
EAST.
TODAY...THE AFOREMENTIONED STRONG UPPER JET AXIS DRIFTS
NORTHEAST...WITH ITS CENTER ALONG AN AXIS FROM CENTRAL ND TO
NORTHERN IL BY 00Z THIS EVENING. AS A RESULT...THE EXTENSIVE HIGH
LEVEL CLOUD COVER ACROSS MOST OF THE CWA SHOULD GRADUALLY SCATTER
OUT AND/OR LIFT NORTHEAST AS WELL...WITH AT LEAST PARTLY CLOUDY
SKIES ANTICIPATED MOST AREAS FOR THIS AFTERNOON. EVEN IF THE SUN
IS OUT...IT WON/T DO A WHOLE LOT TO MASK WHAT IS ALMOST CERTAINLY
TO BE THE OVERALL COLDEST DAY OF THE WINTER SO FAR FOR MOST OF THE
CWA. AS THE DAY WEARS ON...THE CENTER OF THE SURFACE HIGH WILL
MIGRATE INTO MN/IA...ALLOWING BREEZES TO GRADUALLY DIMINISH INTO
THE 5-10 MPH RANGE FOR THIS AFTERNOON AS THEY GRADUALLY SHIFT FROM
MORE NORTHERLY TO MORE EASTERLY/SOUTHEASTERLY BY LATE IN THE DAY.
AS FOR TEMPS...YET AGAIN OPTED TO LOWER HIGHS BY 2-5 DEGREES FROM
PREVIOUS FORECAST IN MOST AREAS...LEANING TOWARD THE COLDER MAV
GUIDANCE. THIS YIELDS HIGHS RANGING FROM ONLY 10-13 DEGREES IN THE
NORTHEAST CWA...TO MID 20S FAR SOUTH AND WEST WHERE THE SOUTHEAST
FLOW AROUND THE HIGH SHOULD HELP MODERATE THINGS SOMEWHAT. AS FOR
WIND CHILLS THIS MORNING...VALUES WILL CONTINUE TO RANGE BETWEEN
-10 AND -17 ACROSS MUCH OF THE NORTHEAST 1/2 OF THE CWA THROUGH AT
LEAST MID-MORNING...WHICH WILL BE ABOVE ADVISORY CRITERIA OF -20
BUT NOT BY MUCH. ITS CLOSE ENOUGH THAT WILL PUT A MENTION IN THE
HAZARDOUS WEATHER OUTLOOK.
TONIGHT...THE NEXT BATCH OF BROAD...LOW AMPLITUDE SHORTWAVE ENERGY
QUICKLY APPROACHES THE CENTRAL CONUS FROM THE NORTHWEST. WITHIN
THE ENTRANCE REGION OF THE PRIMARY UPPER JET AXIS MIGRATING ACROSS
THE UPPER MISS VALLEY/GREAT LAKES...AN IMPRESSIVE ZONE OF
ISENTROPIC LIFT/MID LEVEL CONVERGENCE WILL SET UP ALONG AND NORTH OF
THE PRIMARY LOW-MID LEVEL TEMPERATURE GRADIENT CENTERED FROM SD
INTO NORTHEAST NEB/IA. THIS WILL BE THE OBVIOUS FOCUS FOR THE
START OF A MEASURABLE SNOW EVENT FOR THOSE AREAS. ALTHOUGH IT IS
SEEMING MORE AND MORE LIKELY THAT THE CWA WILL MISS OUT ON THIS
ACTION...PREVIOUS FORECAST HAD SOME LOW POPS ACROSS THE
NORTHEAST...AND WILL CONTINUE THIS MENTION AFTER MIDNIGHT FOR
MAINLY THE NORTHEAST 1/5 OF THE CWA JUST IN CASE THE FAR SOUTHERN
EDGE OF THIS ACTIVITY SLIPS IN. ANY ACCUMULATIONS...IF ANY...WOULD
NOT AMOUNT TO MORE THAN A FEW TENTHS. INTERESTINGLY...IF ANYTHING
DOES HAPPEN TO FALL IN THE FAR NORTH TONIGHT...IT MIGHT ACTUALLY
FAVOR THE FORM OF LIGHT SLEET BASED ON FORECAST SOUNDINGS...BUT
WILL LEAVE IT AS SNOW MENTION FOR NOW. HAVE ALSO BEEN GROWING A
BIT LEARY OF POSSIBLE LIGHT FREEZING DRIZZLE ACROSS NORTHERN
PORTIONS OF THE AREA GIVEN THE GOOD LOW LEVEL WARM ADVECTION...BUT
THINKING AT THIS POINT IS THAT ANY POTENTIAL STRATUS LAYER WOULD
BE TOO SHALLOW TO SUPPORT THIS. SOMETHING TO WATCH. AS FOR LOW
TEMPS...CHANGED THEM LITTLE...ALTHOUGH CONFIDENCE IN HOURLY TRENDS
IS QUITE LOW AS TEMPS COULD EASILY DISPLAY STEADY/SLOWLY RISING
CHARACTERISTICS AS BREEZES TURN SOUTHERLY. KEPT IT SIMPLE FOR NOW
THOUGH...INDICATING MOST AREAS BOTTOMING OUT BETWEEN 9 AND 15
DEGREES...ALTHOUGH THIS MIGHT END UP BEING EARLIER IN THE NIGHT
VERSUS LATER FOR SOME PLACES.
FRIDAY...THE MAIN BATCH OF SHORTWAVE ENERGY PASSES THROUGH THE
CENTRAL PLAINS...ALTHOUGH THE UPPER JET FORCING CONTINUES TO
DIRECT THE MAIN PRECIP EVENT FROM EASTERN SD INTO NORTHERN
IA/SOUTHERN MN AND POINTS EAST. THUS LEFT PRECIP MENTION OUT OF
THE FORECAST...ALTHOUGH ONCE AGAIN WILL HAVE TO MONITOR DEPTH OF
POSSIBLE STRATUS LAYER CLOSELY FOR OUTSIDE CHANCE OF SNEAKY LIGHT
FREEZING DRIZZLE THREAT...BUT JUST SEEMS RATHER UNLIKELY AT THIS
JUNCTURE. AS FOR HIGH TEMPS...THE SOUTHERN EDGE OF THE ARCTIC COLD
FRONT WILL PLAY A BIG ROLE AS IT IS PROGGED TO DROP RIGHT BACK
SOUTH ACROSS THE CWA OVER THE COURSE OF THE DAY...ALTHOUGH THE GFS
IS MUCH MORE AGGRESSIVE THAN THE LATEST ECMWF/NAM REGARDING WITH
THIS COLD PUSH. CONSENSUS OF SEVERAL MODELS/GUIDANCE WAS TO...YOU
GUESSED IT...LOWER TEMPS SEVERAL DEGREES...AND BUMPED DOWN 3-5
DEGREES MOST AREAS...NOW ADVERTISING MID 20S NORTHEAST TO UPPER
30S SOUTHWEST. INTERESTING TO NOTE THAT THIS DAY HAS NOW TRENDED
15+ DEGREES COLDER THAN FORECASTS ISSUED JUST 2-3 DAYS AGO.
FRIDAY NIGHT...IT REMAINS DRY AS A SURFACE RIDGE AXIS SLIDES
ACROSS THE CENTRAL PLAINS...AND A BRIEF BIT OF SHORTWAVE RIDGING
SETS IN ALOFT. ASSUMING LIMITED CLOUD COVER...TEMPS COULD TAKE A
DECENT TUMBLE...AND LOWERED LOWS 5 DEGREES MOST AREAS WITH SINGLE
DIGITS ABOVE ZERO NOW IN PLACE FOR MUCH OF THE CWA.
SATURDAY...THE NEXT...MORE VIGOROUS MID LEVEL WAVE STARTS MAKING
ITS WAY ACROSS THE CENTRAL/SOUTHERN ROCKIES...INDUCING SURFACE
PRESSURE FALLS AND RAMPING UP SOUTH-SOUTHEAST BREEZES INTO AT
LEAST THE 15-20 MPH SUSTAINED RANGE. DESPITE THIS SOUTHERLY
WIND...THE DIRECTION IS NOT OVERLY CONDUCIVE FOR SIGNIFICANT
WARMING...AND HAVE ONLY INDICATED A MODEST WARM-UP OVER
FRIDAY...WITH HIGHS RANGING FROM LOW 30S FAR EAST TO LOW 40S FAR
WEST.
SATURDAY NIGHT...LEFT THIS PERIOD DRY...AT LEAST FOR NOW...AS THE
INCOMING SHORTWAVE CONTINUES TO AMPLIFY/STRENGTHEN AS A 100+KT
UPPER JET STARTS TO ROUND THE BASE INTO THE CENTRAL PLAINS. ONLY
THING KEEPING POPS FROM BEING INSERTED AT THIS POINT IS SUGGESTION
THAT A MID LEVEL DRY SLOT WILL BE IN PLACE ACROSS THE CWA...WITH
MAIN FORCING/MID LEVEL DEFORMATION AXIS HOLDING JUST OFF TO THE
NORTH/WEST...THUS HOLDING OFF BETTER PRECIP CHANCES UNTIL SUNDAY
AS DISCUSSED BELOW.
LONG TERM...SUNDAY THROUGH WEDNESDAY. PATTERN REMAINS
PROGRESSIVE THROUGH THE EXTENDED PERIODS WITH CHALLENGE OF TRYING
TO TIME WAVES. BEGINNING ON SUNDAY...A 100+KT JET NOSES EAST FM
THE FOUR CORNERS REGION AND LIFTS NORTHEAST ACROSS THE CENTRAL
PLAINS DEEPENING THE MID/UPPER TROUGH ACROSS THE CENTRAL PLAINS.
THE 00Z ECMWF IS THE STRONGEST/SLOWEST WITH THE SYSTEM ON SUNDAY
AND CLOSES OFF THE H7 LOW...WHEREAS OTHER EXTENDED MODELS SUGGEST
A MORE PROGRESSIVE OPEN WAVE. IN GENERAL...THERE IS CONSENSUS
AMONG MODELS THAT OUR REGION WILL BE UNDER THE INFLUENCE OF A
TROUGH THRU AT LEAST THE FIRST HALF OF THE DAY...OR LONGER IF
SLOWER ECWMF VERIFIES. COOL FRONTAL BOUNDARY WILL SWEEP ACROSS OUR
REGION IN MORNING WITH AN AREA OF LOW CLOUDS/PCPN ACCOMPANYING
SYSTEM AIDED BY ENHANCED UPPER DYNAMICS IN LFQ OF JET. HOW LONG
PCPN/LOW CLOUDS LINGERS IS DEPENDENT ON STRENGTH OF SYSTEM AND IF
SYSTEM MOVES THRU FASTER...CLEARING SKIES/DOWNSLOPE CONDITIONS MAY
AID IN SOME WARMING FOR THE AFTN. IN ADDITION TO THE PCPN
POTENTIAL...MODELS ALSO SUGGEST STRONG WIND POTENTIAL SUNDAY WITH
NAM INDICATING 3HR PRESSURE RISES OF 6MB BEHIND THE FRONT IN
TIGHTENING SFC GRADIENT...WHILE A CORRIDOR OF 50 TO 60KT MID
LEVEL WINDS CROSS OUR REGION. WILL NEED TO MONITOR MODEL TRENDS OF
THIS AS WELL. FOR PCPN TYPE ON SUNDAY...HAVE WENT WITH R/S IN THE
MORNING TRANSITIONING TO RAIN IN AFTN AS TEMPS LOOK TO RISE ABOVE
FREEZING.
HEADING INTO SUNDAY NIGHT...THE TROUGH AXIS DEPARTS AND CONDITIONS
DRY WITH RISING HEIGHTS BEHIND THE EXITING SYSTEM. MODELS ARE STILL
LOOKING DRY MONDAY IN BETWEEN SYSTEMS...AND THEN NEXT WAVE IS PROGGED
TO EMERGE ONTO THE PLAINS ON TUESDAY. THERE IS STILL SOME
UNCERTAINTY ON DEGREE OF MOISTURE WITH THIS NEXT SYSTEM BUT SMALL
CHCS FOR PCPN STILL WARRANTED AS CURRENTLY FORECAST. MILD AIRMASS IN PLACE
SHLD MAINTAIN LIQUID CHCS INITIALLY WITH POTENTIAL FOR CHANGE TO
SNOW IN COOLER AIR WITH FROPA TUESDAY NIGHT.
THE AIRMASS IN GENERAL DURING THE EXTENDED IS NOT OVERLY COLD AND
TEMPS LOOK TO BE MORE DEPENDENT ON CLOUDS/PCPN.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
310 PM EST THU JAN 19 2012
.SYNOPSIS...
A COLD FRONT WILL BRING SNOW SQUALLS TO THE REGION TONIGHT AND
EARLY FRIDAY MORNING. FRIDAY NIGHT, A STRONGER STORM WILL MOVE
THROUGH THE MID ATLANTIC. THIS STORM WILL BRING MODERATE SNOW TO
THE SOUTHERN TIER OF NY, CATSKILLS, AND NORTHEASTERN PA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EVENT #1 IS VISIBLE ON RADAR, WITH BUF SHOWING ENHANCED RETURNS
OVER THE WESTERN EDGE OF LAKE ONTARIO. THIS SHARP COLD FRONT IS
WELL DEPICTED BY THE LATEST RUC13 LOW LEVEL LAPSE RATES, AND WE
ARE USING THIS MESOSCALE MODEL TO FORECAST A POTENTIAL SQUALL
MOVING THROUGH THE FINGER LAKES AND CENTRAL SOUTHERN TIER BY 2-4Z.
BASED ON CURRENT RADAR UPSTREAM AND THE STEEP LAPSE RATES, I CAN
SEE A QUICK INCH OR TWO FROM THIS SQUALL ALONE BEING POSSIBLE. WE
WILL NEED TO CONTINUE TO MONITOR THIS FOR A POTENTIAL SPS TONIGHT.
ONCE THE COLD FRONT MOVES THROUGH, WINDS SHIFT OFF THE LAKE
OVERNIGHT AND BRING A SOLID 2 TO 4 INCHES OF ADDITIONAL SNOW TO
NORTHERN ONEIDA.
NOW BELIEVE THE BAND WILL AFFECT EXTREME NORTHERN ONONDAGA,
NORTHWESTERN MADISON, AND SOUTHWESTERN ONEIDA WITH 1 TO 3 INCHES
OF SNOW. THIS ON TOP OF THE 1 TO 2 INCHES OF SYNOPTIC SNOWFALL
JUSTIFIES AN ADVISORY, THOUGH ONLY A SMALL PORTION OF THE NEW
ADVISORY COUNTIES WILL BE AFFECTED.
A COMBINATION OF SHEAR AND DECREASING LAPSE RATES IN ASSOCIATION
WITH FAST APPROACHING ANTICYCLONE WILL KILL OFF THE LAKE MACHINE
BY MID MORNING. A FEW LIGHT SNOW SHOWERS MAY PERSIST INTO EARLY
AFTERNOON, BUT THE ADVISORY WILL NO LONGER BE NEEDED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
EVENT #2 HAS A STORM SYSTEM SLIDING THROUGH THE MID ATLANTIC
REGION FRIDAY NIGHT INTO SATURDAY. GFS REMAINS THE QUICKEST TO
MOVE SNOW IN FRIDAY EVENING, WITH THE EURO AND NAM A FEW HOURS
SLOWER. HOWEVER THERE IS GOOD AGREEMENT IN STORM TRACK, STRENGTH,
AND QPF.
THE MODELS WERE COLDER THIS MORNING, BUT THE TREND ALL WINTER HAS
BEEN FOR THE MODELS TO BRING THE STORM CENTERS TO THE NORTH IN THE
FINAL RUNS, WITH WARM AIR ENCROACHING FROM THE SOUTH. THERE ARE
SOME HINTS THAT SOME SLEET COULD MIX IN WITH THE SNOW OVER OUR FAR
SOUTHERN FA, BUT RIGHT NOW THE MODEL SOUNDINGS ARE MOST INDICATIVE
OF SNOW.
THE MODEL QPF LOOKS A LITTLE ON THE HIGH SIDE. HOWEVER EVEN WITH A
REDUCTION IN QPF WE ARE VERY CLOSE TO ADVISORY ACCUMS OVER THE
SOUTHERN THIRD OF THE FA.
THE STORM PULLS OUT QUICKEST ON THE GFS, WITH THE EURO AND NAM
AGAIN A FEW HOURS SLOWER. EITHER WAY THE EVENT SHOULD BE DONE BY
LATE AFTERNOON SATURDAY, IF NOT SOONER. WINDS SHIFT AROUND TO A
NORTHEASTERLY DIRECTION, SO IT DOES NOT APPEAR AS THOUGH OUR FA
WILL BE DEALING WITH POST EVENT LAKE SNOWS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
HGTS BLD SUN NGT WITH MID AND LL WAA AHD OF A WRN LAKES LOW. LGT
PCPN SEEM PSBL WITH MUCH UNCERTAINTY ABT THE TEMP PROFILE. MIXED
PCPN SEEMS LIKELY WITH SFC TEMPS NEAR OR BLO FRZG...SO SOME FRZG
RAIN PSBL. LOW MVES SLWLY EAST AS AN OCCLUDED FNT RACES EWRD THRU
THE OH VLY AND WRN NY. TIMING PUSHES THE FNT THRU THE AREA MON
EVE...BUT WITH MODIFIED COLD AIR PUSHING IN FROM THE SW...DO NOT
XPCT A DRAMATIC TEMP DROP LATE MON INTO TUE. UPR LOW LIFTS NORTH
TUE AS THE TROF AXIS PASSES. AIR IS JUST NOT THAT COLD WITH H8
TEMPS FCSTD IN THE -6C TO -8C RANGE. XPCT SOME MOISTURE WITH THE
UPR TROF AND SOME MRGNL LE SNOW SHWRS INTO WED. LATE WED A SFC HI
OVER THE OH VLY BLDS IN BUT WITH ZONAL FLOW OVER THE FCST
AREA...TEMPS RATHER NEUTRAL AND WITH A WEAK SFC TROF AND APRCHG
WC...JUST SOME LGT PCPN IN THE AREA FOR THE END OF THE PD.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
COLD FNT WILL PASS THRU THE AREA ARND 00Z BRINGING SNOW SHWRS AND
MVFR/IFR CONDS. PCPN SHD BE BRIEF INVOF THE FNT...HWVR...CAA BHD
THE FNT WILL TRIGGER LE SNOWS AND PROLONGED LWR CONDS AT RME. AS
THE FLOW BECOMES MORE NWLY...LE WILL BREAK AWAY FROM THE ALKE AND
BRING SOME OCNL MVFR CONDS TO STATIONS IN CNTRL NY THRU THE END OF
THE PD. GUSTY SLY WINDS AHD OF THE FNT WILL BECOME WLY AND GUSTY
BHD THE FNT EARLY THIS EVE.
.OUTLOOK...
FRI AFTN...MVFR BECOMING VFR AS LE SNOW WINDS DOWN.
SAT...MVFR/IFR IN SNOW.
SUN...MAINLY VFR.
MON..MVFR POSSIBLE IN RAIN OR SNOW.
TUE...MVFR IN SNOW SHWRS
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...WINTER WEATHER ADVISORY UNTIL 11 AM EST FRIDAY FOR NYZ018-036-
037.
WINTER WEATHER ADVISORY UNTIL 9 AM EST FRIDAY FOR NYZ009.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP
SHORT TERM...DJP
LONG TERM...DGM
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
254 PM EST THU JAN 19 2012
.SYNOPSIS...
A COLD FRONT WILL BRING SNOW SQUALLS TO THE REGION TONIGHT AND
EARLY FRIDAY MORNING. FRIDAY NIGHT, A STRONGER STORM WILL MOVE
THROUGH THE MID ATLANTIC. THIS STORM WILL BRING MODERATE SNOW TO
THE SOUTHERN TIER OF NY, CATSKILLS, AND NORTHEASTERN PA.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
EVENT #1 IS VISIBLE ON RADAR, WITH BUF SHOWING ENHANCED RETURNS
OVER THE WESTERN EDGE OF LAKE ONTARIO. THIS SHARP COLD FRONT IS
WELL DEPICTED BY THE LATEST RUC13 LOW LEVEL LAPSE RATES, AND WE
ARE USING THIS MESOSCALE MODEL TO FORECAST A POTENTIAL SQUALL
MOVING THROUGH THE FINGER LAKES AND CENTRAL SOUTHERN TIER BY 2-4Z.
BASED ON CURRENT RADAR UPSTREAM AND THE STEEP LAPSE RATES, I CAN
SEE A QUICK INCH OR TWO FROM THIS SQUALL ALONE BEING POSSIBLE. WE
WILL NEED TO CONTINUE TO MONITOR THIS FOR A POTENTIAL SPS TONIGHT.
ONCE THE COLD FRONT MOVES THROUGH, WINDS SHIFT OFF THE LAKE
OVERNIGHT AND BRING A SOLID 2 TO 4 INCHES OF ADDITIONAL SNOW TO
NORTHERN ONEIDA.
NOW BELIEVE THE BAND WILL AFFECT EXTREME NORTHERN ONONDAGA,
NORTHWESTERN MADISON, AND SOUTHWESTERN ONEIDA WITH 1 TO 3 INCHES
OF SNOW. THIS ON TOP OF THE 1 TO 2 INCHES OF SYNOPTIC SNOWFALL
JUSTIFIES AN ADVISORY, THOUGH ONLY A SMALL PORTION OF THE NEW
ADVISORY COUNTIES WILL BE AFFECTED.
A COMBINATION OF SHEAR AND DECREASING LAPSE RATES IN ASSOCIATION
WITH FAST APPROACHING ANTICYCLONE WILL KILL OFF THE LAKE MACHINE
BY MID MORNING. A FEW LIGHT SNOW SHOWERS MAY PERSIST INTO EARLY
AFTERNOON, BUT THE ADVISORY WILL NO LONGER BE NEEDED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/...
EVENT #2 HAS A STORM SYSTEM SLIDING THROUGH THE MID ATLANTIC
REGION FRIDAY NIGHT INTO SATURDAY. GFS REMAINS THE QUICKEST TO
MOVE SNOW IN FRIDAY EVENING, WITH THE EURO AND NAM A FEW HOURS
SLOWER. HOWEVER THERE IS GOOD AGREEMENT IN STORM TRACK, STRENGTH,
AND QPF.
THE MODELS WERE COLDER THIS MORNING, BUT THE TREND ALL WINTER HAS
BEEN FOR THE MODELS TO BRING THE STORM CENTERS TO THE NORTH IN THE
FINAL RUNS, WITH WARM AIR ENCROACHING FROM THE SOUTH. THERE ARE
SOME HINTS THAT SOME SLEET COULD MIX IN WITH THE SNOW OVER OUR FAR
SOUTHERN FA, BUT RIGHT NOW THE MODEL SOUNDINGS ARE MOST INDICATIVE
OF SNOW.
THE MODEL QPF LOOKS A LITTLE ON THE HIGH SIDE. HOWEVER EVEN WITH A
REDUCTION IN QPF WE ARE VERY CLOSE TO ADVISORY ACCUMS OVER THE
SOUTHERN THIRD OF THE FA.
THE STORM PULLS OUT QUICKEST ON THE GFS, WITH THE EURO AND NAM
AGAIN A FEW HOURS SLOWER. EITHER WAY THE EVENT SHOULD BE DONE BY
LATE AFTERNOON SATURDAY, IF NOT SOONER. WINDS SHIFT AROUND TO A
NORTHEASTERLY DIRECTION, SO IT DOES NOT APPEAR AS THOUGH OUR FA
WILL BE DEALING WITH POST EVENT LAKE SNOWS.
&&
.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
PATTERN OF A GENERAL SOUTHWEST FLOW WITH OCCASIONAL WAVES...WILL ALTERNATE
US ON EITHER SIDE OF THE 540 DECAMETER LINE IN REGARDS TO
1000-500MB THICKNESS. REGARDLESS OF PRECIPITATION TYPE DURING THE
PERIOD...IT WILL BE A WARMER THAN NORMAL PATTERN FOR LATE
JANUARY...A THEME THAT HAS DOMINATED MOST OF THIS WINTER SO FAR.
WE BEGIN SATURDAY NIGHT THROUGH SUNDAY MORNING...BETWEEN WAVES
WITH SEASONABLY COLD LOWS AND MAINLY DRY WEATHER. AN EXTENSION OF
A SOUTHERN STREAM UPPER WAVE MAY SKIM US LATE SUNDAY INTO MONDAY
MORNING. IF PRECIPITATION MANAGES TO REACH US...GENERAL SET UP AND
GFS MODEL SOUNDINGS SUGGEST THERE IS SOME PROSPECT FOR A LIGHT
WINTRY MIX INITIALLY BEFORE PLAIN RAIN. GFS/ECWMF AGREE BETTER
THOUGH...ON A NORTHERN STREAM TROUGH THEN SWINGING THROUGH LATE
MONDAY OR MONDAY NIGHT. THE COLD AIR BEHIND THAT SYSTEM LOOKS
PRETTY MEAGER...SO UNLESS BETTER PENETRATION OF COLDER AIR
OCCURS...THE RESULTING LAKE RESPONSE ON TUESDAY ALSO LOOKS
MEDIOCRE. WE MAY END UP JUST HAVING SCATTERED SNOW SHOWERS SIMPLY
FROM SYNOPTIC WRAP AROUND/COMMA HEAD OF SYSTEM...WITH NOT A WHOLE
LOT OF ASSISTANCE FROM THE LAKES. THE DOMINANT SOUTHWEST FLOW
QUICKLY BRINGS IN WARMER AIR AND SURFACE HIGH PRESSURE INTO
WEDNESDAY...AND TEMPERATURES LOOK TO BE ROUGHLY 10 DEGREES ABOVE
NORMAL AT THAT TIME. NORTH ATLANTIC OSCILLATION INDEX IS POSITIVE
NOW...AND IS FORECAST TO REMAIN POSITIVE THIS WEEK...SUPPORTING
THE WARMER THAN NORMAL PATTERN.
&&
.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
COLD FNT WILL PASS THRU THE AREA ARND 00Z BRINGING SNOW SHWRS AND
MVFR/IFR CONDS. PCPN SHD BE BRIEF INVOF THE FNT...HWVR...CAA BHD
THE FNT WILL TRIGGER LE SNOWS AND PROLONGED LWR CONDS AT RME. AS
THE FLOW BECOMES MORE NWLY...LE WILL BREAK AWAY FROM THE ALKE AND
BRING SOME OCNL MVFR CONDS TO STATIONS IN CNTRL NY THRU THE END OF
THE PD. GUSTY SLY WINDS AHD OF THE FNT WILL BECOME WLY AND GUSTY
BHD THE FNT EARLY THIS EVE.
.OUTLOOK...
FRI AFTN...MVFR BECOMING VFR AS LE SNOW WINDS DOWN.
SAT...MVFR/IFR IN SNOW.
SUN...MAINLY VFR.
MON..MVFR POSSIBLE IN RAIN OR SNOW.
TUE...MVFR IN SNOW SHWRS
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 11 AM EST
FRIDAY FOR NYZ018-036-037.
WINTER WEATHER ADVISORY UNTIL 9 AM EST FRIDAY FOR NYZ009.
&&
$$
SYNOPSIS...DJP
NEAR TERM...DJP
SHORT TERM...DJP
LONG TERM...MDP
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1240 PM EST THU JAN 19 2012
.SYNOPSIS...
MUCH OF TODAY WILL FEATURE DRY WEATHER...AND SEASONABLY CHILLY
TEMPERATURES. A COLD FRONT WILL CROSS THE AREA THIS EVENING...ACCOMPANIED
BY SNOW SHOWERS...AND A FEW SQUALLS. BEHIND THE FRONT...A BRIEF
PERIOD OF LAKE EFFECT SNOW SHOULD IMPACT UPSTATE NEW YORK LATE
TONIGHT AND EARLY FRIDAY...BEFORE DIMINISHING IN THE AFTERNOON. A
FAST MOVING STORM SYSTEM SHOULD TRACK INTO THE MID-ATLANTIC STATES
BY SATURDAY...PERHAPS BRINGING A PERIOD OF SNOW OR MIXED
PRECIPITATION TO START THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
930 AM UPDATE...LATEST HRRR REFLECTIVITY SUGGESTS IF THERE IS A
SQUALL, IT WILL ARRIVE WELL AFTER SUNSET. WE WILL CONTINUE TO
WATCH THE MESOSCALE MODEL TRENDS AND THE OBS/SAT FOR CLUES AS TO
TIMING AND INTENSITY OF SNOW SHOWERS.
CURRENT GRIDS HAVE BEEN TWEAKED FOR TEMPS. OTHERWISE THE FORECAST
LOOKS TO BE IN GOOD SHAPE.
7 AM UPDATE... JUST MINOR TWEAKS TO TEMP/SKY GRIDS.
INITIAL BAND OF HIGH-LVL CLDS IS ERODING ATTM...SO WE ADJUSTED TO
GO FOR A SUNNIER AM PD...BEFORE THICKER CLDS COME IN FROM THE W
TWDS MIDDAY.
OTHWS...NO SIG CHANGES.
PREV DISC... 5 AM UPDATE...ALL IS QUIET EARLY THIS MRNG...AND
SHOULD REMAIN SO FOR MUCH OF THE DAY...WITH JUST AN INCREASE IN
MAINLY MID AND HIGH-LVL CLDS FROM MIDDAY ON. TEMPS SHOULD REBOUND
INTO THE UPPER 20S OR LOWER 30S FOR MANY LOCALES THIS AFTN...WITH
A FAIRLY ROBUST SRLY FLOW DVLPG (HILLTOP SXNS GUSTING TO NEAR 30
MPH AFTER 18Z).
A SHARP COLD FRNT WAS CROSSING CNTRL MI AND THE CHICAGO AREA JUST
PRIOR TO SUNRISE. THE FRNT WAS MAKING STEADY EWD PROGRESS...AND
ALL NEAR-TERM GUIDANCE IS IN AGREEMENT THAT THIS SYSTEM WILL STRETCH
ACRS WRN NY BY 21Z. AS MOIST AND FORCING BEGIN TO INCREASE IN
ADVANCE OF THIS SYSTEM...SCTD SHSN AND FLRYS SHOULD DEVELOP IN OUR
NRN/WRN ZNS BY LATE IN THE DAY...SPCLY THE SRN TUG HILL
RGN...WHERE SRLY UPSLOPE FLOW WILL BE WELL ESTABLISHED.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
530 AM UPDATE... THE ABV MENTIONED COLD FRNT WILL CROSS THE FA
THIS EVE...GENERALLY IN THE 00-04Z TIME FRAME...LIKELY ACCOMPANIED
BY A FEW SQUALLS...SPCLY N AND W OF KBGM. ALTHOUGH LOW-LVL LR`S
SEEM TO BE A BIT SHORT OF WHAT WE`D NORMALLY SEE IN A FRNTL
SQUALL/WINDEX SITN...THEY ARE STILL IN THE 7-8C/KM RANGE IN THE
LOWEST 3 KM AGL. THE SUPPORTING UPPER-LVL TROUGH IS ALSO FAIRLY
DYNAMIC IN NATURE...AND GOOD LOW-LVL CAA FOLLOWS BEHIND THE SFC
FRNT. THUS...WE FEEL SOME AREAS WILL SEE A QUICK INCH OR SO OF
ACCUM THIS EVE...MOSTLY CNY.
AFTER A 3-5 HOUR PERIOD OF MOSTLY DRY WX...OR PERHAPS A FEW FLRYS/-SHSN...
FOR THE LATE EVE/OVERNIGHT TIME FRAME...THE LES MACHINE SHOULD
KICK INTO GEAR E AND SE OF LK ONT IN THE PRE-DAWN HRS (06-09Z).
NWP AGREEMENT (NAM12/LOCAL WRF/GFS40) IS PRETTY GOOD THAT A SINGLE
BAND WILL FIRST IMPACT OSWEGO/LEWIS CNTYS...BEFORE DROPPING INTO
NRN ONEIDA BY 08-09Z. FOR A RELATIVELY SHORT PD EARLY FRI...A
MULTI-LK INFLUENCE WITH GEO BAY LOOKS PSBL...WHICH WOULD HELP TO
ENHANCE MOIST DEPTHS/DZ FAVORABILITY. DUE TO THE COMBO OF 1-3"
EARLIER THU EVE WITH THE FRNT...AND THEN AN ADDITIONAL SEVERAL
INCHES OF LAKE EFF ACCUM EARLY FRI...A WINTER WX ADVSY HAS BEEN
POSTED FOR NRN ONEIDA.
PRESENT INDICATIONS ARE THAT THE MAIN LES BAND WILL GRADUALLY
WEAKEN AFTER 12Z FRI...AS IT DROPS SWD THROUGH
ONONDAGA/MADISON/SRN ONEIDA CNTYS...AND INTO
CORTLAND/CHENANGO/OTSEGO CNTYS. A LOWERING INVERSION...COMPROMISED
DENDRITE PRODUCTION...AND INCREASED DIR SHEAR...SHOULD ALL TAKE
THEIR TOLL...LIKELY CAUSING ACCUMS TO DROP OFF WITH TIME. OUR SRN
ZNS SHOULD ONLY SEE A FEW FLRYS AT WORST...WITH PROBABLE BREAKS OF
SUNSHINE BY AFTN.
AFTER A BRIEF LULL EARLY FRI EVE...THE NEXT SYNOPTIC SYSTEM IS
SLATED TO QUICKLY ARRIVE. MODEL EVOLUTION IS ALL PRETTY SIMILAR AT
THIS PT...TAKING A FAST MOVING SFC WAVE FROM THE OH/TN VLYS LATE
FRI NGT...TO THE DELMARVA RGN ON SAT. ALTHOUGH A STG WAA PATN
BECOMES ESTABLISHED THIS PD ACRS NE PA/CNY...ALG WITH A DEEPENING
MOIST SUPPLY...THE MAIN UPPER-LVL WAVE IS RATHER FLAT AND FAST
MOVG...AND THIS RAPID SYSTEM MOVEMENT COULD WELL KEEP PCPN AMTS
DOWN. MY GUT FEELING IS THAT MODEL QPF`S OF 0.3-0.5" LIQUID ARE A
BIT OVERDONE...BUT EVEN IF THEY ARE...SEVERAL INCHES OF SNOW ARE
STILL PSBL. WE`LL ALSO HAVE TO WATCH FOR THE PSBLTY THAT AN
ELEVATED WARM LYR BECOMES INCORPORATED...WHICH COULD POTENTIALLY
CREATE A WINTRY MIX SITN FOR PTNS OF THE FA. WE`LL BE MONITORING
THIS SYSTEM CLOSELY OVER THE NEXT COUPLE OF DAYS.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
PATTERN OF A GENERAL SOUTHWEST FLOW WITH OCCASIONAL WAVES...WILL
ALTERNATE US ON EITHER SIDE OF THE 540 DECAMETER LINE IN REGARDS
TO 1000-500MB THICKNESS. REGARDLESS OF PRECIPITATION TYPE DURING
THE PERIOD...IT WILL BE A WARMER THAN NORMAL PATTERN FOR LATE
JANUARY...A THEME THAT HAS DOMINATED MOST OF THIS WINTER SO FAR.
WE BEGIN SATURDAY NIGHT THROUGH SUNDAY MORNING...BETWEEN WAVES
WITH SEASONABLY COLD LOWS AND MAINLY DRY WEATHER. AN EXTENSION OF
A SOUTHERN STREAM UPPER WAVE MAY SKIM US LATE SUNDAY INTO MONDAY
MORNING. IF PRECIPITATION MANAGES TO REACH US...GENERAL SET UP AND
GFS MODEL SOUNDINGS SUGGEST THERE IS SOME PROSPECT FOR A LIGHT
WINTRY MIX INITIALLY BEFORE PLAIN RAIN. GFS/ECWMF AGREE BETTER
THOUGH...ON A NORTHERN STREAM TROUGH THEN SWINGING THROUGH LATE
MONDAY OR MONDAY NIGHT. THE COLD AIR BEHIND THAT SYSTEM LOOKS
PRETTY MEAGER...SO UNLESS BETTER PENETRATION OF COLDER AIR
OCCURS...THE RESULTING LAKE RESPONSE ON TUESDAY ALSO LOOKS
MEDIOCRE. WE MAY END UP JUST HAVING SCATTERED SNOW SHOWERS SIMPLY
FROM SYNOPTIC WRAP AROUND/COMMA HEAD OF SYSTEM...WITH NOT A WHOLE
LOT OF ASSISTANCE FROM THE LAKES. THE DOMINANT SOUTHWEST FLOW
QUICKLY BRINGS IN WARMER AIR AND SURFACE HIGH PRESSURE INTO
WEDNESDAY...AND TEMPERATURES LOOK TO BE ROUGHLY 10 DEGREES ABOVE
NORMAL AT THAT TIME. NORTH ATLANTIC OSCILLATION INDEX IS POSITIVE
NOW...AND IS FORECAST TO REMAIN POSITIVE THIS WEEK...SUPPORTING
THE WARMER THAN NORMAL PATTERN.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
COLD FNT WILL PASS THRU THE AREA ARND 00Z BRINGING SNOW SHWRS AND
MVFR/IFR CONDS. PCPN SHD BE BRIEF INVOF THE FNT...HWVR...CAA BHD
THE FNT WILL TRIGGER LE SNOWS AND PROLONGED LWR CONDS AT RME. AS
THE FLOW BECOMES MORE NWLY...LE WILL BREAK AWAY FROM THE ALKE AND
BRING SOME OCNL MVFR CONDS TO STATIONS IN CNTRL NY THRU THE END OF
THE PD. GUSTY SLY WINDS AHD OF THE FNT WILL BECOME WLY AND GUSTY
BHD THE FNT EARLY THIS EVE.
.OUTLOOK...
FRI AFTN...MVFR BECOMING VFR AS LE SNOW WINDS DOWN.
SAT...MVFR/IFR IN SNOW.
SUN...MAINLY VFR.
MON..MVFR POSSIBLE IN RAIN OR SNOW.
TUE...MVFR IN SNOW SHWRS
&&
.BGM WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NY...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 9 AM EST
FRIDAY FOR NYZ009.
&&
$$
SYNOPSIS...MLJ
NEAR TERM...DJP/MLJ
SHORT TERM...MLJ
LONG TERM...MDP
AVIATION...DGM
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
320 PM CST THU JAN 19 2012
.SHORT TERM...TONIGHT THROUGH SUNDAY
320 PM CST THU JAN 19 2012
MAIN FORECAST CONCERNS ARE ON THE ACCUMULATING SNOW EVENT FOR LATE
TONIGHT INTO FRIDAY...AS WELL AS A MIXED PRECIPITATION EVENT FOR
SUNDAY.
CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS
SHOWED A WEST-NORTHWEST FLOW FROM THE PACIFIC NORTHWEST INTO THE
OHIO VALLEY WITH A TROUGH OVER THE WESTERN GREAT LAKES REGION.
ALSO NOTED ON WATER VAPOR IS A SHORTWAVE TROUGH JUST OFF THE COAST
OF OREGON. FAST JET STREAM IN THE WEST-NORTHWEST FLOW...WITH THE
RUC TROPOPAUSE WIND SPEEDS SHOWING 130-160KT FROM FAR SOUTHERN
SASKATCHEWAN INTO FAR WESTERN KENTUCKY. WITH THE FORECAST AREA ON
THE NORTHEAST/SUBSIDENT SIDE OF THE UPPER JET AND ON THE BACK SIDE
OF THE WESTERN GREAT LAKES TROUGH...HIGH PRESSURE IS FAVORED AT
THE SURFACE. THIS HIGH IS CENTERED OVER SOUTHERN MINNESOTA AND
IOWA. ARCTIC AIR REMAINS IN PLACE...NOTED BY SURFACE TEMPERATURES
ONLY JUST ABOVE ZERO...DESPITE PLENTY OF SUN. 12Z SOUNDING PLOT OF
850MB TEMPERATURES REFLECTIVE OF BOTH THE ARCTIC AIR AND THE FAST
UPPER JET...WITH READINGS OF -21 TO -25C AT ABR...MPX AND GRB
WHILE ONLY -9C AT OAX AND -12C AT DVN. A SIMILAR DRAMATIC
DIFFERENCE CAN BE SEEN IN PRECIPITABLE WATER PLOTS. ABR...MPX AND
GRB HAD READINGS OF 0.05 TO 0.1 INCHES OR 20-30 PERCENT OF
NORMAL...WHILE DVN AND OAX REPORTED 0.26 INCHES OR ALMOST 100
PERCENT OF NORMAL. LAST ITEM OF NOTE IS A FRONTOGENETIC BAND OF
SNOW OVER CENTRAL MONTANA. THIS AREA OF FRONTOGENESIS IS ALONG THE
WESTERN EXTENT OF THE AFOREMENTIONED SHARP CONTRAST IN
MOISTURE/850MB TEMPS.
TONIGHT AND FRIDAY...UPPER LEVEL FLOW IS PROGGED TO TURN MORE
WESTERLY/ZONAL DURING THE NEXT 24 HOURS...MOSTLY IN RESPONSE TO THE
TROUGH OFF THE OREGON COAST RAPIDLY MOVING INLAND. THIS TROUGH IS
VERY IMPORTANT TO THE FORECAST AND SPECIFICALLY HOW AMPLIFIED IT IS
AS IT MOVES THROUGH THE CENTRAL PLAINS ON FRIDAY. THE REASON IS THAT
AS THE DPVA AND WARM ADVECTION APPROACHES AHEAD OF THE TROUGH...THE
SHARP CONTRAST IN TEMPERATURES AND MOISTURE NOTED IN THE CURRENT
DISCUSSION WILL LIGHT UP WITH SNOW. ANOTHER FEATURE HELPING TO
PRODUCE THE SNOW WILL END UP BEING A RIGHT ENTRANCE REGION OF THE
CURRENT STRONG UPPER JET...WHICH LIFTS NORTHEAST TONIGHT AND FRIDAY
WITH THE CHANGE IN UPPER FLOW. THEREFORE...WHERE THIS SNOW BAND SETS
UP AND HOW STRONG DEPENDS ON THE AMPLITUDE OF THE TROUGH. RUN TO RUN
THE NAM HAS BEEN THE MOST POTENT WITH THIS TROUGH...THOUGH IT HAS
SPED UP SOME TO COME IN CLOSER WITH THE CONSENSUS WITH THE 19.12Z
RUN. THE CANADIAN HAS BEEN CONSISTENTLY SHOWING A LESS POTENT
TROUGH...KEEPING THE HEAVIER BAND MOSTLY SOUTH OF THE FORECAST
AREA...THOUGH THE LATEST 19.12Z RUN SHOWED A SLIGHT NORTHWARD DRIFT.
THE GFS REMAINS A CONSISTENT COMPROMISE APPROACH BETWEEN THE
CANADIAN AND NAM. ANOTHER ISSUE TO DEAL WITH REMAINS SNOW RATIOS. A
FLATTER SOLUTION ALLOWS FOR A SLOWER EXIT OF THE CURRENT ARCTIC
AIR...SETTING THE STAGE FOR A DEEPER DENDRTIC SNOW GROWTH LAYER.
THIS IS ESPECIALLY TRUE FOR ABOUT THE NORTHERN TWO THIRDS OF THE
FORECAST AREA...WHERE 20 TO 1 SNOW RATIOS ARE LIKELY...NO MATTER
WHAT SOLUTION IS FOLLOWED. ON THE OTHER HAND...THE MORE AMPLIFIED
SOLUTION LIKE THE NAM ADVECTS WARMER MID LEVEL AIR INTO THE
SOUTHERN THIRD OF THE FORECAST AREA...DECREASING THE DENDRITIC
GROWTH ZONE. AROUND 15 TO 1 RATIOS WOULD BE MORE REASONABLE IN
THIS ZONE. IN TERMS OF TIMING...GOOD CONSENSUS FOR THE SNOW TO
MOVE INTO AREAS WEST OF THE MISSISSIPPI RIVER BETWEEN
09-12Z...OVERSPREAD MUCH OF THE AREA FOR 12-18Z WHICH ALSO LOOKS
TO BE THE HEAVIEST SNOW TIME...THEN BEGIN TO EXIT WEST TO EAST
BETWEEN 18-00Z. TRICKY DETERMINING THE HAZARD SCENARIO WITH
QUESTIONS ON THE SNOW TO WATER RATIO AS WELL AS PLACEMENT OF THE
HEAVIER BAND. HIGH CERTAINTY THAT LOCATIONS ALONG AND SOUTH OF
I-90 WILL SEE ADVISORY CRITERIA. NOT ENOUGH CERTAINTY EXISTS TO
PLACE ANY WARNINGS...THOUGH...WITH THE UNCERTAINTY ON MAX QPF
PLACEMENT...FORCING AND SNOW TO WATER RATIOS. 19.15Z SREF PLUMES
ALSO SHOWS A LARGE AMOUNT OF UNCERTAINTY REGARDING AMOUNTS. FUTURE
SHIFTS MAY UPGRADE TO WARNINGS IF THE ZONE OF HEAVIEST QPF CAN BE
NARROWED DOWN. QUICKLY REGARDING TEMPERATURES...SHOULD SEE LOWS
THIS EVENING THEN READINGS RISE AFTER MIDNIGHT TONIGHT INTO FRIDAY
WITH THE CLOUDS/WARM ADVECTION MOVING IN.
FRIDAY NIGHT AND SATURDAY...SHORTWAVE TROUGH THAT MOVED INTO THE
CENTRAL PLAINS FRIDAY CONTINUES HEADING RAPIDLY OFF TO THE EAST
FRIDAY NIGHT...ALLOWING HIGH PRESSURE TO BUILD OVER THE ENTIRE
AREA BY SATURDAY MORNING. SKIES LOOK TO CLEAR AS THE HIGH MOVES
IN...THEREFORE...WITH THE FRESH SNOW WENT TOWARDS THE LOW END OF
GUIDANCE FOR LOWS. FOR SATURDAY...MODELS ARE IN GOOD AGREEMENT
BRINGING A DEEP TROUGH INTO THE WESTERN U.S. AS THIS OCCURS...
HEIGHTS BUILD DOWNSTREAM OVER THE FORECAST AREA...RESULTING IN
FAIRLY STRONG WARM ADVECTION BY THE END OF THE DAY. 850MB TEMPS
CLIMB FROM -8 TO -12C AT 12Z SATURDAY TO -2 TO -6C BY 00Z SUNDAY.
NOT ANTICIPATING ANY PRECIPITATION ON SATURDAY...DUE TO THE DRY
HIGH PRESSURE AREA STILL IN PLACE...THOUGH AN INCREASE OF MID AND
HIGH CLOUD COVER IS LIKELY AS THE DAY GOES ON. GENERALLY FOLLOWED
A BLEND OF GUIDANCE FOR HIGHS.
SATURDAY NIGHT AND SUNDAY...FOCUS OF ATTENTION IS ON THAT NEXT DEEP
TROUGH IN THE WESTERN U.S. AT 00Z SUNDAY. DPROG/DT OF ALL MODELS
SHOWS THIS TROUGH TRENDING RAPIDLY DEEPER AND SLOWING SOMEWHAT.
RIGHT NOW MOST MODELS ARE IN AGREEMENT OF THE TROUGH MOVING INTO THE
PLAINS ON SUNDAY. ALSO OF NOTE IS THAT A POTENT SHORTWAVE IS
INDICATED AT THE BOTTOM OF THE TROUGH...WHICH MAY TURN NEGATIVE TILT
AS IT LIFTS UP THE EAST SIDE OF THE TROUGH TOWARDS THE FORECAST AREA
LATE SUNDAY AND INTO SUNDAY NIGHT. THIS MEANS THE WEATHER IS GOING
TO BE ACTIVE AGAIN...BUT THIS TIME THE TROUGH HAS A SURGE OF WARM
AND MORE MOIST AIR FROM THE GULF OF MEXICO...RESULTING IN ISSUES
WITH PRECIPITATION TYPE. FIRST FOR SATURDAY NIGHT...WARM ADVECTION
DOWNSTREAM SHOULD ALLOW TEMPERATURES TO CLIMB THROUGH THE NIGHT.
ANY PRECIPITATION ASSOCIATED WITH THE WARM ADVECTION LOOKS TO STAY
OFF TO OUR NORTHWEST...MAINLY OVER WESTERN AND NORTHERN MINNESOTA.
BETTER SHOT FOR PRECIPITATION EXISTS ON SUNDAY...ESPECIALLY IN THE
AFTERNOON...AS HEIGHT FALLS FROM THE UPPER TROUGH AND ISENTROPIC
LIFT AHEAD OF THE TROUGH MOVES INTO THE AREA. WITH THE PERSISTENT
WARM ADVECTION...2 METER TEMPERATURES ARE LIKELY TO CLIMB ABOVE
FREEZING FOR MOST OF THE AREA...RESULTING IN POTENTIAL FOR A
MIX/CHANGE TO RAIN AND SNOW. WITH GROUND AND SNOW TEMPERATURES
PROBABLY STAYING BELOW FREEZING...THIS RAIN COULD TURN TO ICE ON
UNTREATED ROADS...THUS THE INTRODUCTION OF FREEZING RAIN TOO INTO
THE FORECAST. NOTE...THERE IS A MID LEVEL DRY AIR LAYER NOTED IN
SOUNDINGS...THOUGH IT DOES NOT LOOK TO BE DEEP ENOUGH OR DRY ENOUGH
AT THIS TIME TO PREVENT ICE FROM ALOFT REACHING DOWN TO THE SURFACE.
.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY
320 PM CST THU JAN 19 2012
UPPER TROUGH OVER THE PLAINS LOOKS TO LIFT NORTHEAST THROUGH THE
AREA SUNDAY NIGHT AND AWAY FROM THE AREA ON MONDAY. CERTAINLY THIS
BEARS WATCHING FOR TIMING GIVEN THE TREND FOR THIS TROUGH TO BE
AMPLIFIED AND SLOWER. IN FACT THE NEW 19.12Z ECMWF SLOWED DOWN THE
TROUGH A BIT MORE. SHOULD SEE ANY RAIN/FREEZING RAIN CHANGE OVER TO
SNOW THROUGH THE NIGHT SUNDAY NIGHT...WITH ALL SNOW MONDAY...THOUGH
AGAIN THE PRECIPITATION SHOULD BE WINDING DOWN MONDAY. MAY HAVE TO
WATCH FOR POTENTIAL ADVISORY SNOW SUNDAY NIGHT...AND POSSIBLY INTO
MONDAY IF THE NEW ECMWF IS CORRECT.
REST OF NEXT WEEK CONTINUES TO SHOW A SOMEWHAT ACTIVE PATTERN...WITH
MODELS IN VERY GOOD AGREEMENT SHOWING SHORTWAVE TROUGHS MOVING
THROUGH TUESDAY NIGHT INTO WEDNESDAY...AS WELL AS ON THURSDAY.
HOWEVER...NONE OF THESE TROUGHS LOOK TO HAVE A LOT OF MOISTURE WITH
THEM...LIKELY SHUNTED OFF BY THE DEEPER SUNDAY NIGHT/MONDAY TROUGH.
FOLLOWED A CONSENSUS APPROACH GIVEN THE GOOD AGREEMENT...RESULTING
IN MOSTLY 20-40 PERCENT CHANCES FOR THESE TROUGHS. TEMPERATURES WILL
BE WARMER NEXT WEEK THAN THIS WEEK...THANKS TO THE MAIN POLAR
WESTERLIES SHIFTING WELL NORTH INTO CANADA. IT DOES NOT APPEAR THAT
ENOUGH WARM AIR ENTERS ANY OF THE TROUGHS TO RESULT IN LIQUID
PRECIPITATION...THOUGH.
&&
.AVIATION...THROUGH 18Z FRIDAY
1134 AM CST THU JAN 19 2012
SHORT WAVE TROUGH COMING ON TO THE PACIFIC NORTHWEST COAST WILL
QUICKLY MOVE ACROSS THE ROCKIES AND INTO THE MIDWEST BY LATE
TONIGHT. THE 19.12Z NAM AND GFS ARE BOTH IN AGREEMENT THAT THE
WAVE WILL BE MOVING RAPIDLY WITH LITTLE CHANCE FOR AMPLIFICATION
AS IT COMES THROUGH WITH A POSITIVE TILT. THIS WILL BRING A NARROW
AND QUICK SHOT OF 12 TO 16 PVU/S OF PV ADVECTION IN THE 500-300 MB
LAYER FRIDAY MORNING. THERE WILL BE SOME WEAK TO MODERATE
FRONTOGENESIS THAT SETS UP IN THE 850-500 MB LAYER FOR FRIDAY
MORNING AND COMBINED WITH 2 TO 4 UBAR/S OF UP GLIDE ON THE 280
THROUGH 290K ISENTROPIC SURFACES...THERE WILL BE ENOUGH FORCING
TO PRODUCE A PERIOD OF SNOW FOR BOTH TAF SITES. VFR CONDITIONS
WILL PREVAIL UNTIL THE SNOW STARTS AND SHOULD THEN SEE AN ABRUPT
DROP TO IFR FOR BOTH THE VISIBILITY AND CEILINGS. FORCING COULD BE
STRONG ENOUGH TO PRODUCE A 3 TO 4 HOUR PERIOD OF VISIBILITIES DOWN
TO ABOUT A MILE WITH SUB 1000 FOOT CEILINGS. EXPECTING THE SNOW
TO START IN THE 10 TO 12Z TIME FRAME WITH THE WORST CONDITIONS
EXPECTED A COUPLE OF HOURS AFTER THE SNOW INITIALLY BEGINS.
APPEARS AS FAST THE SNOW COMES IN...IT WILL ALSO END...BUT THIS IS
NOT EXPECTED TO OCCUR UNTIL AFTER 18Z FRIDAY.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
320 PM CST THU JAN 19 2012
WI...WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM CST FRIDAY FOR
WIZ041>044-053>055-061.
MN...WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CST FRIDAY FOR
MNZ086>088-094>096.
IA...WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CST FRIDAY FOR
IAZ008>011-018-019-029-030.
&&
$$
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...04