AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
930 PM PST SUN JAN 25 2009
.SYNOPSIS...A FAST MOVING TROUGH OF LOW PRESSURE WILL RACE ACROSS
SOUTHERN CALIFORNIA TONIGHT AND MONDAY BRINGING COOL WEATHER...GUSTY
WEST WINDS AND SCATTERED SHOWERS. THE TROUGH WILL MOVE EAST ON
TUESDAY FOLLOWED BY GRADUALLY WARMING AS HIGH PRESSURE BUILDS OVER
THE WEST. SANTA ANA CONDITIONS WILL BRING GUSTY OFFSHORE WINDS
THROUGH THE MOUNTAIN PASSES AT TIMES TUESDAY THROUGH FRIDAY.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
IR SATELLITE IMAGERY SHOWS CLOUDS FILLING IN OVER THE COASTAL WATERS
THIS EVENING AND SPREADING INLAND. DEEP MOIST LAYER TO 6000
FEET IS IN PLACE...AND SCATTERED LIGHT SHOWERS WERE FORMING OFF THE
SAN DIEGO COUNTY COAST AT 05Z. THESE SHOWERS WILL INCREASE IN
COVERAGE AND SPREAD INLAND OVERNIGHT AHEAD OF A FAIRLY POTENT
SHORTWAVE EMBEDDED IN THE MEAN WEST COAST TROUGH. WINDS WILL ALSO
INCREASE OVERNIGHT...ESPECIALLY IN SAN DIEGO COUNTY...AS A NARROW
JET CORE (300 MB WINDS TOPPED 100 KTS ON THE 00Z NKX SOUNDING)
TRACKS OVERHEAD. EXPECT A PERIOD OF GUSTY WINDS LATER TONIGHT AND
MONDAY...STRONGEST OVER THE SAN DIEGO COUNTY MOUNTAINS WITH WINDS
FROM 20 TO 30 MPH GUSTING TO 45 MPH AT TIMES. SURFACE WINDS OVER THE
COASTAL WATERS WILL ALSO PICK UP TONIGHT AND THE SMALL CRAFT
ADVISORY LOOKS ON TARGET.
MONDAY WILL BE COLDEST DAY THIS WEEK. 850 MB TEMPS FALL BELOW ZERO
AND HIGH TEMPS WILL BE STUCK IN THE 50S TO LOW 60S WEST OF THE MTNS
AND IN THE 30S AND LOW 40S IN THE MTNS...WITH SNOW LEVELS AROUND
4500 FEET.
STRONG DYNAMICS AND AN INFUSION OF COLD AIR MONDAY WILL PRODUCE OFF
AND ON SHOWERS THROUGH MONDAY NIGHT...ENHANCED BY A SECOND SHORTWAVE
PINWHEELING AROUND THE BASE OF THE TROUGH. BEHIND THIS TROUGH THE
FLOW ALOFT TURNS QUICKLY OFFSHORE...DRAWING A DRIER AIRMASS IN FROM
THE NORTHEAST AND ENDING RAIN SHOWERS FROM NORTH TO SOUTH TUESDAY
MORNING.
PRECIPITATION AMOUNTS WILL BE GREATEST ON THE WEST FACING MTN SLOPES
DUE TO THE ENHANCED OROGRAPHIC LIFT FROM THE STRONG WESTERLY ONSHORE
FLOW. PROJECTIONS ARE FOR A QUARTER TO HALF IN ON THE MTN SLOPES
WITH LESSER AMOUNTS WEST OF THE MOUNTAINS.
WEDNESDAY THROUGH SATURDAY...HIGH PRESSURE BUILDS OVER THE WEST WITH
SANTA ANA CONDITIONS THROUGH WEEKS END WITH GUSTY NORTHEAST WINDS AT
TIMES. TEMPERATURES WILL REBOUND NICELY WITH WARMING EACH DAY
THROUGH FRIDAY...ROUNDING OUT THE MONTH OF JANUARY WITH ABOVE
AVERAGE TEMPERATURES.
&&
.AVIATION...260330Z
BASED ON SURFACE OBSERVATIONS AND MDCRS SOUNDINGS IT APPEARS THE
MARINE LAYER DEPTH IS ABOUT 4K FT AT THE COAST...AND SLOPES UP TO 7K
FT THICK NEAR THE FOOTHILLS. THE DEEP MOIST WESTERLY FLOW WILL
INCREASE INTO MON... PUSHING CLOUDS AND LIGHT PRECIPITATION UP
AGAINST THE COASTAL SLOPES. EXPECT THE HIGHER TERRAIN WILL REMAIN
OBSCURED THROUGH MON AND WESTERLY WINDS WILL TOP THE RIDGES WITH
GUSTS OF 45 TO 50 MPH POSSIBLE AT TIMES. THIS COULD PRODUCE STRONG
UP AND DOWN DRAFTS AND MOUNTAIN WAVES OVER ADJACENT DESERT AREAS
THROUGH MONDAY. CIG FORECASTS WILL BE PROBLEMATIC AND CONFIDENCE IS
LOW ON HEIGHT AND TIMING. BASES EXPECTED TO BE MOSTLY BETWEEN FL020
AND FL050 THROUGH MON WITH TOPS UP TO FL080. AREAS OF LIGHT
PRECIPITATION WILL DEVELOP MON AS AN UPPER TROUGH DEEPENS OVER THE
AREA AND NARROW CONVECTIVE BANDS DEVELOP IN THE LEE OF THE ISLANDS.
MVFR VIS COULD DEVELOP LOCALLY AT TIMES IN AREAS OF PRECIP. THE
FREEZING LEVEL WILL DROP TO NEAR 5K FT ON MON...WHICH WILL MAKE
LIGHT FREEZING PRECIPITATION LIKELY AT ELEVATIONS ABOVE 4K FT MSL.
&&
.MARINE...
STRONG WESTERLY WINDS BETWEEN 20 AND 30 KTS HAVE DEVELOPED OVER THE
COASTAL WATERS AND WILL CONTINUE THROUGH MON AFTERNOON. A SMALL
CRAFT ADVISORY IS IN EFFECT. THE STRONG WINDS WILL GENERATE ROUGH
SEAS MAKING FOR HAZARDOUS CONDITIONS THROUGH MONDAY. THE WINDS WILL
DECREASE LATE MONDAY AFTERNOON AS GRADIENTS WEAKEN.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY UNTIL 4 PM PST MONDAY FOR THE COASTAL WATERS.
SEE LAXCWFSGX AND LAXMWWSGX.
&&
$$
PUBLIC...MOEDE
AVIATION/MARINE...JAD
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1052 PM EST TUE JAN 27 2009
.SYNOPSIS...
LOW PRESSURE OVER THE TENNESSEE VALLEY WILL MOVE NORTHEASTWARD
TONIGHT AND WEDNESDAY. THE LOW WILL MOVE THROUGH OUR AREA LATE
WEDNESDAY AND EARLY WEDNESDAY NIGHT. WEAK HIGH PRESSURE WILL BUILD
INTO THE REGION THURSDAY AND FRIDAY. A COLD FRONT WILL MOVE ACROSS
THE AREA FRIDAY NIGHT INTO SATURDAY FOLLOWED BY A PACIFIC HIGH
PRESSURE SYSTEM FOR THE END OF THE WEEKEND AND EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
BASED ON CURRENT CONDITIONS, OBSERVATIONS, AND REPORTS...WE HAVE
UPDATED THE INLAND ADVISORY TO A WARNING FOR NJ/DE/MD. WILL GO
FOR ICE ACCRETIONS AROUND 1/4 INCH IN THOSE AREAS. PREVIOUS
THINKING REMAINS ON TRACK AS THE STORM APPROACHES.
THE MODEL H5 INITIALIZATION WAS NOT PERFECT IN THE ROCKIES WITH THE
TROF. THE WRF-NMM LOOKED SLIGHTLY BETTER AS IT LOOKS LIKE THERE IS A
LEAD SHORT WAVE THAT THE GFS DID NOT RESOLVE NEAR DENVER. CLOSER TO
HOME THE RNK 12Z SOUNDING WAS THE INTERESTING ONE AS THE MODELS
INITIALIZED THE 850MB TEMPS TOO WARM. OF EQUAL IMPORTANCE IS WHAT
WAS OCCURRING ABOVE THAT LEVEL AS THE 800MB WARMING WAS BETTER
HANDLED BY THE GFS THAN THE WRF-NMM. FROM THERE THE TWO MODELS ARE
AT OPPOSITE ENDS AS TO HOW QUICKLY IT WARMS ABOVE 800MB. THE LAYER
OF COLD AIR BELOW 850MB IS INDICATIVE THAT THE SNOW/NO SNOW LINE IS
AT ABOUT A 1280M 1000-850MB THICKNESS, A PRETTY LOW VALUE FOR
THAT THICKNESS LEVEL. WE ARE SEEING A MODEL SPLIT BETWEEN THE CAN
RGEM/CAN GGEM AND GFS AND THE UKMET/WRF-NMM AND ECMWF WRT TO THERMAL
PROFILES AND ADVECTION OF THE WARMER AIR. SINCE THE MODEL GUIDANCE
IS USUALLY ONE OF TOO SLOW WITH THE WARM AIR ALOFT AND TOO FAST WITH
THE WARM AIR NEAR THE SURFACE, WE ARE GOING TO SLIDE THE FCST
PACKAGE ABOUT HALFWAY BETWEEN THE GFS AND WRF-NMM SOLUTION. TAKING
THE GFS SOLUTION LOCK STOCK AND BARREL WOULD HAVE NECESSITATED A
TREMENDOUS DROP IN CURRENT SNOW ACCUM FCSTS. THIS IS NOT MADE EASY
AS THE HEAVIEST PCPN IS SLATED TO ARRIVE WITH THE WARMER AIR ALOFT.
FOR EVERY HOUR WE ARE WRONG, YOU CAN ADD OR SUBTRACT ABOUT ANOTHER
HALF INCH TO INCH OF SNOW.
IN TERMS OF FORCING WE ARE NOT SEEING ROBUST FCST OMEGAS IN THE SNOW
DENDRITIC GROWTH AREAS AND THE BEST MID LEVEL FRONTOGENETIC FORCING
INCREASES AS THE NIGHT AND WEDNESDAY GET GOING WHICH WOULD FAVOR
POSSIBLY ONLY OUR FAR NORTHERN CWA. THERE ARE SOME STEEP LAPSE RATES
FCST TO ARRIVE IN OUR FAR NW ZONES DURING WED MRNG, BUT THIS MIGHT
BE TOO LATE FOR BANDED SNOW. CHOOSE ONE`S POISON BECAUSE IF IT ISN`T
SNOW, IT WILL BE SLEET OR FREEZING RAIN ALL IN ALL A VERY MESSY
MORNING COMMUTE FOR A BIG CHUNK OF THE PHL CWA.
NO CHANGES WERE MADE TO ADVISORIES OR WARNINGS WITH THIS PACKAGE. IN
AREAS (AROUND PHL METRO AREA) WHERE THE SNOW CRITERIA IS NOT BEING
MET THE WARNING IS FOR THE COMBINATION OF SNOW, SLEET AND FREEZING
RAIN.
IN GENERAL TERMS, WE SLOWED THE GFS FCST 1000-850MB THICKNESS OF NO
SNOW BY ABOUT 1-3 HRS AND WAS CLOSE TO A COMPROMISE POSITION BETWEEN
THE GFS AND WRF-NMM FCST SOUNDINGS. WE KEPT SNOW IN MOST OF OUR CWA
UNTIL ABOUT MIDNIGHT WHERE THE SNOW-NO SNOW LINE (POINTS NORTH STILL
MENTION SNOW) ADVANCES NORTHWARD AND GOES FROM CENTREVILLE MD TO
LEWES DE. AT 3 AM ITS FROM ABOUT ROCK HALL MD TO ACY INTL NJ; AT 6
AM FROM ILG AND PHL EAST TO TOM`S RIVER; AT 9 AM FROM RDG TO
SOMERVILLE NJ. BY NOON ANY SNOW SHOULD BE CONFINED TO JUST THE
POCONOS. WITH THE FRESH SNOW COVER WE WENT SLIGHTLY SLOWER THAN GFS
MOS WITH RAISING TEMPS ABOVE FREEZING WITH ZR CONTINUING INTO THE
MORNING IN THE LOCAL PHL AREA AND POSSIBLY INTO THE AFTERNOON FROM
THE PHL NW SUBURBS NORTHWARD THRU THE DAY. THE ONE CONSOLATION IS
THAT TEMPERATURES WILL BE CLOSE TO MELTING AND COUPLED WITH THE
INDIRECT SUN SHOULD MINIMIZE SOMEWHAT THE IMPACT OF THE FREEZING
RAIN DURING THE DAY.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
PRECIPITATION MIGHT CHANGE TO SNOW BEFORE IT ENDS AS FAR SE AS THE
PHL NORTHWEST SUBURBS. LOOKS LIKE PCPN IS CUTTING OFF AS IT CHANGES,
SO WE DID NOT EXTEND THE WARNING FOR NOW. CWA MAINLY SHOULD BE
BETWEEN SYSTEMS ON THURSDAY SO WE LIMITED FLURRIES TO THE HIGHER
TERRAIN LOCATIONS. WE GENERALLY UNDERCUT GUIDANCE BECAUSE OF THE
FRESH SNOW/ICE COVER EXPECTED IN OUR CWA.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THANKS TO A LONGWAVE MID-LEVEL TROUGH THAT HAS BECOME COMPLACENT
OVER THE EASTERN HALF OF THE UNITED STATES, OUR WEATHER PATTERN WILL
REMAIN FAIRLY ACTIVE. DO NOT SEE ANY BLOCKBUSTER SYSTEMS ON THE
HORIZON BUT MODELS INDICATE WEAK RIDGING, NUMEROUS VORTICITY MAXES
AND SHORTWAVES SLINKING THROUGH THE REGION IN THE LONG TERM PERIOD.
UPPER LEVEL TROUGHING WILL SWING THROUGH THE REGION ON FRIDAY IN THE
WAKE OF THE LOW PRESSURE SYSTEM THAT AFFECTED OUR REGION ON TUESDAY
AND WEDNESDAY. MODELS INDICATE A VERY WEAK SURFACE COLD FRONT
PENETRATES THE REGION DURING THE DAY ON FRIDAY. ISENTROPIC LIFT
LOOKS RATHER BLEAK AND WE ARE NOT EXPECTING TOO MUCH IN THE WAY OF
PRECIPITATION WITH THIS COLD FRONTAL PASSAGE. ONCE THE FRONT PUSHES
THROUGH WE RETURN TO A NORTHWEST FLOW REGIME AND THIS FLOW IS
ENHANCED BY ANTI-CYCLONIC TURNING BROUGHT ON BY A BUILDING SURFACE
HIGH PRESSURE SYSTEM.
THE RIDGE AXIS SETS UP OVER THE REGION SATURDAY EVENING INTO SUNDAY
MORNING AND BECOMES THE DOMINANT FORCE IN THE MIDDLE ATLANTIC, AT
LEAST FOR A COUPLE OF DAYS. ONCE THE HIGH STARTS TO MOVE FURTHER
EAST WE START TO SEE AND FEEL RETURN FLOW WITH TEMPERATURES
MODERATING AROUND NORMALCY.
LOW PRESSURE MAKES A QUICK BRUSH BY TO OUR NORTH ON TUESDAY AND
SWINGS ANOTHER WEAK COLD FRONT THROUGH DURING THE EARLY MORNING. FOR
SIMPLICITY`S SAKE, HAVE LOADED IN WIDESPREAD SHOWERY PRECIPITATION
FOR TUESDAY`S EVENT. TEMPERATURES APPEAR TO BE COLD ENOUGH FOR ALL
SNOW.
&&
.AVIATION /04Z WEDNESDAY THROUGH SUNDAY/...
THE PRECIPITATION SHIELD, IN THE FORM OF SNOW, CONTINUES TO ADVANCE
EASTWARD AND EXPAND SOME. AS LOW PRESSURE TRACKS OUR WAY TONIGHT,
CONDITIONS ARE EXPECTED TO DETERIORATE. THE SNOW INITIALLY IS
EXPECTED TO BE LIGHT ALTHOUGH VISIBILITIES AND CEILINGS WILL BE ON
THE DECLINE. BASED ON RADAR TRENDS, WE TRIED TO SPEED UP THE
STEADIER SNOW SOME IN THE LATEST TAFS. WE EXAMINED THE LATEST
AVAILABLE ACARS SOUNDINGS AT KPHL AND THERE IS WARMING NOTED ALREADY
AROUND 9,000 FEET. HOWEVER, THE TEMPERATURE PROFILE IS STILL ALL
BELOW FREEZING. WE ARE STILL EXPECTING ALL TERMINALS TO START OUT AS
SNOW, THEN AS WARMING CONTINUES TO OCCUR ALOFT, THE SNOW WILL MIX
WITH SLEET THEN CHANGE TO A WINTRY MIX THEN TO PLAIN RAIN FROM
SOUTHEAST TO NORTHWEST. KACY AND KMIV ARE EXPECTED TO HAVE THE LEAST
FROZEN/FREEZING PRECIPITATION WITH KABE AND KRDG HOLDING ON LONGER.
FOR THE KPHL METRO AREA AIRPORTS, WE CONTINUED THE IDEA OF THE
TRANSITION TAKING PLACE A LITTLE AFTER MIDNIGHT BUT ADDED IN SLEET
TO THE MIX SOONER. AS A SIDE NOTE, THE AIR AT ABOUT 9,000 FEET IN
THE WASHINGTON AREA HAS WARMED ABOVE FREEZING AND SLEET AND FREEZING
RAIN IS NOW BEING REPORTED THERE. THIS WARMING TREND WILL BE KEY
REGARDING OUR PRECIPITATION TYPES AND WILL PROBABLY BE TRICKY. WE
TRIED TO INDICATE THE TREND WHEN WE ANTICIPATE THE CHANGING
PRECIPITATION TYPES, HOWEVER OUR CONFIDENCE IS NOT REAL HIGH. WE
WILL CONTINUE TO MONITOR THE LATEST DATA/OBSERVATIONS AND ISSUE
AMENDMENTS TO REFLECT THE LATEST THINKING.
AS THE PRECIPITATION OVERSPREADS OUR AREA THIS EVENING, THE CEILINGS
ARE EXPECTED TO LOWER AND EVENTUALLY GET INTO THE IFR RANGE WITH
POTENTIALLY SOME LIFR CEILINGS OVERNIGHT AND WEDNESDAY. ON
WEDNESDAY, THE PRECIPITATION IS EXPECTED TO BE CHANGING TO MOSTLY
PLAIN RAIN FROM SOUTH TO NORTH DURING THE EARLY MORNING HOURS. THIS
STORM SYSTEM HAS A LOT OF MOISTURE WITH IT, THEREFORE A RAINY DAY IS
EXPECTED /ALTHOUGH SOME ICING MAY HOLD LONGER AT KABE AND KRDG/. A
DRY SLOT MAY WORK INTO AT LEAST PART OF THE AREA WEDNESDAY, AND THAT
MAY ALLOW FOR A PERIOD OF LIGHTER PRECIPITATION INTENSITY SUCH AS
DRIZZLE. FOR NOW WE DID NOT INCLUDE THIS AT THIS TIME. LOW
CEILINGS AND RESTRICTED VISIBILITIES WILL CONTINUE TO HAVE A HIGH
IMPACT. THE SURFACE WINDS WILL BE LIGHT FOR AWHILE TONIGHT, THEN
GRADUALLY INCREASE FROM THE NORTHEAST AND EAST. DURING WEDNESDAY,
AS THE STORM SYSTEM SLIDES ACROSS OUR AREA, THE WINDS ARE EXPECTED
TO SHIFT TO THE SOUTHEAST AND THEN EVENTUALLY TO THE SOUTHWEST AND
INCREASE SOME MORE TOWARD THE END OF THE TAF PERIOD. THE WINDS MAY
TURN A LITTLE GUSTY FOR AWHILE WEDNESDAY EVENING. FOR KPHL
/30-HOUR TAF/, AN IMPROVEMENT SHOULD TAKE PLACE AFTER 00Z THURSDAY
HOWEVER GIVEN THE IMPACTS IN THE EARLIER PORTIONS OF THE PERIOD,
WE JUST INDICATED SOME IMPROVEMENT AT THAT TIME.
OUTLOOK...
AS THE STORM SYSTEM MOVES TO OUR NORTHEAST WEDNESDAY NIGHT, A COLD
FRONT WILL CROSS THE AREA. THIS WILL DELIVER DRIER AIR INTO OUR
REGION WITH A WIND SHIFT TO THE WEST AND NORTHWEST. HIGH PRESSURE
THEN BUILDS IN FOR THURSDAY INTO FRIDAY. A COLD FRONT IS EXPECTED TO
MOVE THROUGH FRIDAY NIGHT WITH PERHAPS SOME FLURRIES, THEN HIGH
PRESSURE BUILDS BACK IN FOR SATURDAY AND SUNDAY.
&&
.MARINE...
THE START TIME OF THE SMALL CRAFT ADVISORY HAS BEEN DELAYED UNTIL
12Z WEDNESDAY. THIS WAS BASED ON A GRADUAL INCREASE IN WINDS AND
SEAS THROUGH THE OVERNIGHT GIVEN WAA OCCURRING ALOFT.
AS THE LOW PRESSURE SYSTEM APPROACHES THE REGION OVERNIGHT, BOTH
WINDS AND SEAS WILL GRADUALLY INCREASE DUE TO AN ONSHORE FLOW.
SOME SOUNDINGS SUGGEST GALE FORCE GUSTS OCCUR WEDNESDAY NIGHT INTO
THURSDAY MORNING AS THE LOW PULLS AWAY FROM THE REGION AND THE
PRESSURE GRADIENT TIGHTENS. HOWEVER, THIS CONTINUES TO LOOK MARGINAL
AND WE PREFER TO CONTINUE WITH A HIGH END SMALL CRAFT ADVISORY AT
THIS TIME. THIS WILL BE MONITORED IN CASE AN UPGRADE IS NEEDED. THE
SURFACE WINDS WILL SHIFT TO THE SOUTH AND SOUTHWEST WEDNESDAY
AFTERNOON AS THE STORM SYSTEM NEARS. ONCE THE FRONT MOVES THROUGH, A
WIND SHIFT TO THE WEST WILL OCCUR.
WEAK HIGH PRESSURE IS EXPECTED TO BUILD IN BEHIND THE STORM THURSDAY
INTO FRIDAY. A COLD FRONT IS EXPECTED TO CROSS THE AREA WATERS
FRIDAY WITH WINDS AND SEAS EXPECTED TO REACH SMALL CRAFT ADVISORY
CRITERIA, ONCE AGAIN. HIGH PRESSURE IS THEN EXPECTED TO BUILD IN FOR
THE WEEKEND.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 6 PM EST WEDNESDAY FOR PAZ054-055-
060>062-067>069.
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR PAZ070-071.
NJ...WINTER STORM WARNING UNTIL 6 PM EST WEDNESDAY FOR NJZ001-
007>010-012-015.
WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR NJZ021>023.
WINTER WEATHER ADVISORY UNTIL 12 PM EST WEDNESDAY FOR NJZ014-
026.
WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR NJZ024-
025.
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR NJZ013-
016>020-027.
DE...WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR DEZ002-003.
WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR DEZ004.
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR DEZ001.
MD...WINTER STORM WARNING UNTIL 7 AM EST WEDNESDAY FOR MDZ012-015-
019-020.
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR MDZ008.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM WEDNESDAY TO 6 AM EST THURSDAY
FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GIGI
NEAR TERM...RPW/GIGI
SHORT TERM...GIGI
LONG TERM...HEAVENER
AVIATION...GORSE
MARINE...GORSE/MEOLA
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
650 PM EST TUE JAN 27 2009
.SYNOPSIS...
LOW PRESSURE OVER THE TENNESSEE VALLEY WILL MOVE NORTHEASTWARD
TONIGHT AND WEDNESDAY. THE LOW WILL MOVE THROUGH OUR AREA LATE
WEDNESDAY AND EARLY WEDNESDAY NIGHT. WEAK HIGH PRESSURE WILL BUILD
INTO THE REGION THURSDAY AND FRIDAY. A COLD FRONT WILL MOVE ACROSS
THE AREA FRIDAY NIGHT INTO SATURDAY FOLLOWED BY A PACIFIC HIGH
PRESSURE SYSTEM FOR THE END OF THE WEEKEND AND EARLY NEXT WEEK.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
THE MODEL H5 INITIALIZATION WAS NOT PERFECT IN THE ROCKIES WITH THE
TROF. THE WRF-NMM LOOKED SLIGHTLY BETTER AS IT LOOKS LIKE THERE IS A
LEAD SHORT WAVE THAT THE GFS DID NOT RESOLVE NEAR DENVER. CLOSER TO
HOME THE RNK 12Z SOUNDING WAS THE INTERESTING ONE AS THE MODELS
INITIALIZED THE 850MB TEMPS TOO WARM. OF EQUAL IMPORTANCE IS WHAT
WAS OCCURRING ABOVE THAT LEVEL AS THE 800MB WARMING WAS BETTER
HANDLED BY THE GFS THAN THE WRF-NMM. FROM THERE THE TWO MODELS ARE
AT OPPOSITE ENDS AS TO HOW QUICKLY IT WARMS ABOVE 800MB. THE LAYER
OF COLD AIR BELOW 850MB IS INDICATIVE THAT THE SNOW/NO SNOW LINE IS
AT ABOUT A 1280M 1000-850MB THICKNESS, A PRETTY LOW VALUE FOR
THAT THICKNESS LEVEL. WE ARE SEEING A MODEL SPLIT BETWEEN THE CAN
RGEM/CAN GGEM AND GFS AND THE UKMET/WRF-NMM AND ECMWF WRT TO THERMAL
PROFILES AND ADVECTION OF THE WARMER AIR. SINCE THE MODEL GUIDANCE
IS USUALLY ONE OF TOO SLOW WITH THE WARM AIR ALOFT AND TOO FAST WITH
THE WARM AIR NEAR THE SURFACE, WE ARE GOING TO SLIDE THE FCST
PACKAGE ABOUT HALFWAY BETWEEN THE GFS AND WRF-NMM SOLUTION. TAKING
THE GFS SOLUTION LOCK STOCK AND BARREL WOULD HAVE NECESSITATED A
TREMENDOUS DROP IN CURRENT SNOW ACCUM FCSTS. THIS IS NOT MADE EASY
AS THE HEAVIEST PCPN IS SLATED TO ARRIVE WITH THE WARMER AIR ALOFT.
FOR EVERY HOUR WE ARE WRONG, YOU CAN ADD OR SUBTRACT ABOUT ANOTHER
HALF INCH TO INCH OF SNOW.
IN TERMS OF FORCING WE ARE NOT SEEING ROBUST FCST OMEGAS IN THE SNOW
DENDRITIC GROWTH AREAS AND THE BEST MID LEVEL FRONTOGENETIC FORCING
INCREASES AS THE NIGHT AND WEDNESDAY GET GOING WHICH WOULD FAVOR
POSSIBLY ONLY OUR FAR NORTHERN CWA. THERE ARE SOME STEEP LAPSE RATES
FCST TO ARRIVE IN OUR FAR NW ZONES DURING WED MRNG, BUT THIS MIGHT
BE TOO LATE FOR BANDED SNOW. CHOOSE ONE`S POISON BECAUSE IF IT ISN`T
SNOW, IT WILL BE SLEET OR FREEZING RAIN ALL IN ALL A VERY MESSY
MORNING COMMUTE FOR A BIG CHUNK OF THE PHL CWA.
NO CHANGES WERE MADE TO ADVISORIES OR WARNINGS WITH THIS PACKAGE. IN
AREAS (AROUND PHL METRO AREA) WHERE THE SNOW CRITERIA IS NOT BEING
MET THE WARNING IS FOR THE COMBINATION OF SNOW, SLEET AND FREEZING
RAIN.
IN GENERAL TERMS, WE SLOWED THE GFS FCST 1000-850MB THICKNESS OF NO
SNOW BY ABOUT 1-3 HRS AND WAS CLOSE TO A COMPROMISE POSITION BETWEEN
THE GFS AND WRF-NMM FCST SOUNDINGS. WE KEPT SNOW IN MOST OF OUR CWA
UNTIL ABOUT MIDNIGHT WHERE THE SNOW-NO SNOW LINE (POINTS NORTH STILL
MENTION SNOW) ADVANCES NORTHWARD AND GOES FROM CENTREVILLE MD TO
LEWES DE. AT 3 AM ITS FROM ABOUT ROCK HALL MD TO ACY INTL NJ; AT 6
AM FROM ILG AND PHL EAST TO TOM`S RIVER; AT 9 AM FROM RDG TO
SOMERVILLE NJ. BY NOON ANY SNOW SHOULD BE CONFINED TO JUST THE
POCONOS. WITH THE FRESH SNOW COVER WE WENT SLIGHTLY SLOWER THAN GFS
MOS WITH RAISING TEMPS ABOVE FREEZING WITH ZR CONTINUING INTO THE
MORNING IN THE LOCAL PHL AREA AND POSSIBLY INTO THE AFTERNOON FROM
THE PHL NW SUBURBS NORTHWARD THRU THE DAY. THE ONE CONSOLATION IS
THAT TEMPERATURES WILL BE CLOSE TO MELTING AND COUPLED WITH THE
INDIRECT SUN SHOULD MINIMIZE SOMEWHAT THE IMPACT OF THE FREEZING
RAIN DURING THE DAY.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY/...
PRECIPITATION MIGHT CHANGE TO SNOW BEFORE IT ENDS AS FAR SE AS THE
PHL NORTHWEST SUBURBS. LOOKS LIKE PCPN IS CUTTING OFF AS IT CHANGES,
SO WE DID NOT EXTEND THE WARNING FOR NOW. CWA MAINLY SHOULD BE
BETWEEN SYSTEMS ON THURSDAY SO WE LIMITED FLURRIES TO THE HIGHER
TERRAIN LOCATIONS. WE GENERALLY UNDERCUT GUIDANCE BECAUSE OF THE
FRESH SNOW/ICE COVER EXPECTED IN OUR CWA.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
THANKS TO A LONGWAVE MID-LEVEL TROUGH THAT HAS BECOME COMPLACENT
OVER THE EASTERN HALF OF THE UNITED STATES, OUR WEATHER PATTERN WILL
REMAIN FAIRLY ACTIVE. DO NOT SEE ANY BLOCKBUSTER SYSTEMS ON THE
HORIZON BUT MODELS INDICATE WEAK RIDGING, NUMEROUS VORTICITY MAXES
AND SHORTWAVES SLINKING THROUGH THE REGION IN THE LONG TERM PERIOD.
UPPER LEVEL TROUGHING WILL SWING THROUGH THE REGION ON FRIDAY IN THE
WAKE OF THE LOW PRESSURE SYSTEM THAT AFFECTED OUR REGION ON TUESDAY
AND WEDNESDAY. MODELS INDICATE A VERY WEAK SURFACE COLD FRONT
PENETRATES THE REGION DURING THE DAY ON FRIDAY. ISENTROPIC LIFT
LOOKS RATHER BLEAK AND WE ARE NOT EXPECTING TOO MUCH IN THE WAY OF
PRECIPITATION WITH THIS COLD FRONTAL PASSAGE. ONCE THE FRONT PUSHES
THROUGH WE RETURN TO A NORTHWEST FLOW REGIME AND THIS FLOW IS
ENHANCED BY ANTI-CYCLONIC TURNING BROUGHT ON BY A BUILDING SURFACE
HIGH PRESSURE SYSTEM.
THE RIDGE AXIS SETS UP OVER THE REGION SATURDAY EVENING INTO SUNDAY
MORNING AND BECOMES THE DOMINANT FORCE IN THE MIDDLE ATLANTIC, AT
LEAST FOR A COUPLE OF DAYS. ONCE THE HIGH STARTS TO MOVE FURTHER
EAST WE START TO SEE AND FEEL RETURN FLOW WITH TEMPERATURES
MODERATING AROUND NORMALCY.
LOW PRESSURE MAKES A QUICK BRUSH BY TO OUR NORTH ON TUESDAY AND
SWINGS ANOTHER WEAK COLD FRONT THROUGH DURING THE EARLY MORNING. FOR
SIMPLICITY`S SAKE, HAVE LOADED IN WIDESPREAD SHOWERY PRECIPITATION
FOR TUESDAY`S EVENT. TEMPERATURES APPEAR TO BE COLD ENOUGH FOR ALL
SNOW.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
THE PRECIPITATION SHIELD, IN THE FORM OF SNOW, CONTINUES TO ADVANCE
EASTWARD AND EXPAND SOME. AS LOW PRESSURE TRACKS OUR WAY TONIGHT,
CONDITIONS ARE EXPECTED TO DETERIORATE. THE SNOW INITIALLY IS
EXPECTED TO BE LIGHT ALTHOUGH VISIBILITIES AND CEILINGS WILL BE ON
THE DECLINE. BASED ON RADAR TRENDS, WE TRIED TO SPEED UP THE
STEADIER SNOW SOME IN THE LATEST TAFS. WE EXAMINED THE LATEST
AVAILABLE ACARS SOUNDINGS AT KPHL AND THERE IS WARMING NOTED ALREADY
AROUND 9,000 FEET. HOWEVER, THE TEMPERATURE PROFILE IS STILL ALL
BELOW FREEZING. WE ARE STILL EXPECTING ALL TERMINALS TO START OUT AS
SNOW, THEN AS WARMING CONTINUES TO OCCUR ALOFT, THE SNOW WILL MIX
WITH SLEET THEN CHANGE TO A WINTRY MIX THEN TO PLAIN RAIN FROM
SOUTHEAST TO NORTHWEST. KACY AND KMIV ARE EXPECTED TO HAVE THE LEAST
FROZEN/FREEZING PRECIPITATION WITH KABE AND KRDG HOLDING ON LONGER.
FOR THE KPHL METRO AREA AIRPORTS, WE CONTINUED THE IDEA OF THE
TRANSITION TAKING PLACE A LITTLE AFTER MIDNIGHT BUT ADDED IN SLEET
TO THE MIX SOONER. AS A SIDE NOTE, THE AIR AT ABOUT 9,000 FEET IN
THE WASHINGTON AREA HAS WARMED ABOVE FREEZING AND SLEET AND FREEZING
RAIN IS NOW BEING REPORTED THERE. THIS WARMING TREND WILL BE KEY
REGARDING OUR PRECIPITATION TYPES AND WILL PROBABLY BE TRICKY. WE
TRIED TO INDICATE THE TREND WHEN WE ANTICIPATE THE CHANGING
PRECIPITATION TYPES, HOWEVER OUR CONFIDENCE IS NOT REAL HIGH. WE
WILL CONTINUE TO MONITOR THE LATEST DATA/OBSERVATIONS AND ISSUE
AMENDMENTS TO REFLECT THE LATEST THINKING.
AS THE PRECIPITATION OVERSPREADS OUR AREA THIS EVENING, THE CEILINGS
ARE EXPECTED TO LOWER AND EVENTUALLY GET INTO THE IFR RANGE WITH
POTENTIALLY SOME LIFR CEILINGS OVERNIGHT AND WEDNESDAY. ON
WEDNESDAY, THE PRECIPITATION IS EXPECTED TO BE CHANGING TO MOSTLY
PLAIN RAIN FROM SOUTH TO NORTH DURING THE EARLY MORNING HOURS. THIS
STORM SYSTEM HAS A LOT OF MOISTURE WITH IT, THEREFORE A RAINY DAY IS
EXPECTED /ALTHOUGH SOME ICING MAY HOLD LONGER AT KABE AND KRDG/. A
DRY SLOT MAY WORK INTO AT LEAST PART OF THE AREA WEDNESDAY, AND THAT
MAY ALLOW FOR A PERIOD OF LIGHTER PRECIPITATION INTENSITY SUCH AS
DRIZZLE. FOR NOW WE DID NOT INCLUDE THIS AT THIS TIME. LOW
CEILINGS AND RESTRICTED VISIBILITIES WILL CONTINUE TO HAVE A HIGH
IMPACT. THE SURFACE WINDS WILL BE LIGHT FOR AWHILE TONIGHT, THEN
GRADUALLY INCREASE FROM THE NORTHEAST AND EAST. DURING WEDNESDAY,
AS THE STORM SYSTEM SLIDES ACROSS OUR AREA, THE WINDS ARE EXPECTED
TO SHIFT TO THE SOUTHEAST AND THEN EVENTUALLY TO THE SOUTHWEST AND
INCREASE SOME MORE TOWARD THE END OF THE TAF PERIOD. THE WINDS MAY
TURN A LITTLE GUSTY FOR AWHILE WEDNESDAY EVENING. FOR KPHL
/30-HOUR TAF/, AN IMPROVEMENT SHOULD TAKE PLACE AFTER 00Z THURSDAY
HOWEVER GIVEN THE IMPACTS IN THE EARLIER PORTIONS OF THE PERIOD,
WE JUST INDICATED SOME IMPROVEMENT AT THAT TIME.
OUTLOOK...
AS THE STORM SYSTEM MOVES TO OUR NORTHEAST WEDNESDAY NIGHT, A COLD
FRONT WILL CROSS THE AREA. THIS WILL DELIVER DRIER AIR INTO OUR
REGION WITH A WIND SHIFT TO THE WEST AND NORTHWEST. HIGH PRESSURE
THEN BUILDS IN FOR THURSDAY INTO FRIDAY. A COLD FRONT IS EXPECTED TO
MOVE THROUGH FRIDAY NIGHT WITH PERHAPS SOME FLURRIES, THEN HIGH
PRESSURE BUILDS BACK IN FOR SATURDAY AND SUNDAY.
&&
.MARINE...
A SMALL CRAFT ADVISORY REMAINS IN EFFECT ALL MARINE ZONES STARTING
LATE TONIGHT AND PERSISTING THROUGH WEDNESDAY NIGHT.
MARINE CONDITIONS HAVE REMAINED QUIET TODAY WITH SEAS STAYING
BETWEEN 1 AND 3 FEET ACROSS THE AREA WATERS. AS THE LOW PRESSURE
SYSTEM APPROACHES THE REGION TONIGHT, BOTH WINDS AND SEAS WILL
INCREASE TO SMALL CRAFT ADVISORY CONDITIONS AS AN ONSHORE FLOW
STRENGTHENS OVERNIGHT. WAVEWATCH BRINGS GALE FORCE WINDS INTO THE
AREA WEDNESDAY NIGHT INTO THURSDAY MORNING AS THE LOW PULLS AWAY
FROM THE REGION AND TIGHT GRADIENT DEVELOPS. HOWEVER, THIS CONTINUES
TO LOOK MARGINAL AND WE PREFER TO CONTINUE WITH THE SMALL CRAFT
ADVISORY AT THIS TIME. AS LATER MODEL GUIDANCE BECOMES AVAILABLE
THERE MAY NEED TO BE AN UPGRADE TO GALES AND WE WILL CONTINUE TO
MONITOR THIS.
WEAK HIGH PRESSURE IS EXPECTED TO BUILD IN BEHIND THE STORM THURSDAY
INTO FRIDAY. A COLD FRONT IS EXPECTED TO CROSS THE AREA WATERS
FRIDAY WITH WINDS AND SEAS EXPECTED TO REACH SMALL CRAFT ADVISORY
CRITERIA, ONCE AGAIN. HIGH PRESSURE IS THEN EXPECTED TO BUILD IN FOR
THE WEEKEND.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...WINTER STORM WARNING UNTIL 6 PM EST WEDNESDAY FOR PAZ054-055-
060>062-067>069.
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR PAZ070-071.
NJ...WINTER STORM WARNING UNTIL 6 PM EST WEDNESDAY FOR NJZ001-
007>010-012-015.
WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR
NJZ021>025.
WINTER WEATHER ADVISORY UNTIL 12 PM EST WEDNESDAY FOR NJZ013-
014-020-026-027.
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR NJZ016>019.
DE...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR
DEZ002>004.
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR DEZ001.
MD...WINTER WEATHER ADVISORY UNTIL 7 AM EST WEDNESDAY FOR MDZ012-
015-019-020.
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR MDZ008.
MARINE...SMALL CRAFT ADVISORY FROM 3 AM WEDNESDAY TO 6 AM EST THURSDAY
FOR ANZ430-431-450>455.
&&
$$
SYNOPSIS...GIGI
NEAR TERM...GIGI
SHORT TERM...GIGI
LONG TERM...HEAVENER
AVIATION...GORSE
MARINE...MEOLA
AREA FORECAST DISCUSSION
NWS BOISE ID
304 PM MST TUE JAN 27 2009
.SHORT TERM...TONIGHT THROUGH THURSDAY...THE SYSTEM COMING THROUGH
TONIGHT SHARES SOME THINGS IN COMMON WITH THE SYSTEM THAT BROUGHT
THE REGION SNOW BACK ON JAN 5TH DURING THE DAY. BOTH HAVE NW FLOW
ALOFT AND SIMILAR SFC PRESSURE PATTERNS...AND SIMILAR TEMPERATURE
PROFILES. THE JAN 5TH SYSTEM HAD MORE MOISTURE TO WORK WITH...AND
FOR THAT REASON...WILL KEEP FORECASTED TOTAL FOR THIS STORM
SLIGHTLY UNDER WHAT FELL BACK ON THE 5TH. THEREFORE WE WILL NOT
ISSUE AN ADVISORY AT THIS TIME...ALTHOUGH WE EXPECT ENOUGH SNOW TO
COVER THE ROADS TONIGHT. IT APPEARS THAT THE COLD TEMPERATURES WILL
HELP THE LIGHT POWDERY SNOW NOT FORM AN ICY GLAZE ON THE ROADWAYS.
TEMPS WILL REMAIN NEARLY STEADY ALL NIGHT...JUST ABOUT EQUAL TO
WHAT THIS AFTERNOON/S HIGHS END UP BEING. SNOW HAS BEGUN IN BAKER
COUNTY OREGON...AND WILL COMMENCE AT ONTARIO AND MCCALL AROUND 5
PM...BOISE AROUND 7 PM...MOUNTAIN HOME AROUND 9 PM...AND THE
WESTERN MAGIC VALLEY AFTER MIDNIGHT. SOME BANDING OF SNOW IN THE
UPPER TREASURE VALLEY IS INDICATED BY THE LATEST MODELS. SHOULD
ONE OF THESE BANDS SET UP AND REMAIN STATIONARY...A SMALL PORTION
OF THE AREA MAY RECEIVE UP TO 5 INCHES OF SNOW. THE EXACT
LOCATIONS OF THESE BANDS ARE IMPOSSIBLE TO PREDICT IN ADVANCE...
BUT WE CAN RECOGNIZE THE CONDITIONS THAT LEAD TO THEM. SNOW WILL
MOVING THROUGH THE FAR UPPER TREASURE VALLEY AND WESTERN MAGIC
VALLEY AROUND SUNRISE WEDNESDAY...AND THEN MOVE OUT BY NOON. A FEW
SNOW SHOWERS MAY LINGER INTO THE AFTERNOON...BUT ACCUMULATING SNOW
SHOULD BE DONE BY NOON. THE MOUNTAINS WILL SEE 3 TO 6 INCHES OF
VERY POWDERY SNOW OVERNIGHT AND INTO EARLY WEDNESDAY. TEMPERATURES
WILL BEGIN TO WARM UP ON THURSDAY...BUT SLOWLY IN THE AREAS THAT
STILL HAVE SNOW ON THE GROUND. THE MOST RAPID WARMUP IS LIKELY TO
OCCUR OVER SE OREGON.
.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY...MODELS CONTINUE TO
SHOW A HIGH AMPLITUDE RIDGE BUILDING OVER THE REGION THURSDAY NIGHT
WITH THE ECMWF HAVING A LITTLE MORE AMPLITUDE ON FRIDAY WHILE THE
GFS SHOWS A FLATTER RIDGE. EITHER WAY...DRY WEATHER WILL DOMINATE
THE FORECAST AREA WITH TEMPERATURES REBOUNDING TO MORE SEASONAL
VALUES DURING THE PERIOD THURSDAY NIGHT THROUGH FRIDAY NIGHT. A
WEAK WAVE PASSES ACROSS CENTRAL IDAHO SATURDAY MORNING AND THIS IS
SHOWN BY BOTH OPERATIONAL MODELS. HAVE LEFT SCATTERED POPS OVER THE
NORTHERN MOUNTAINS AS PREVIOUS SHIFTS AND ADJACENT OFFICES HAVE TO
ACCOUNT FOR THIS WEAK FEATURE. AS THIS WAVE PASSES...THE EAST
PACIFIC RIDGE ONCE AGAIN BUILDS OVER THE PACIFIC NORTHWEST WHILE
PLENTY OF COLD AIR AND TROFFINESS CONTINUES OVER THE GREAT LAKES AND
EASTERN U.S. THIS WILL SET UP ANOTHER COUPLE DAYS OF DRY WEATHER
AND SEASONAL TEMPERATURES FROM SUNDAY INTO EARLY NEXT WEEK. ABOUT
THE ONLY MAIN CONCERN DURING THE EXTENDED PERIOD IS IF ANOTHER
PROLONGED INVERSION WILL SET UP UNDER THE RIDGE MUCH LIKE WE SAW FOR
A WEEK TO 10 DAY PERIOD RECENTLY. INVERSION INDICES APPROACH THE MID
80S WHICH BY LOCAL STUDIES INDICATES AN INVERSION BECOMING
ESTABLISHED.
&&
.AVIATION...CLOUDS HAVE INCREASED IN COVERAGE AND CEILINGS LOWERED
OVER THE PAST FEW HOURS WITH THE APPROACH OF THE NEXT PACIFIC SHORT
WAVE. CEILINGS AND VSBY REMAIN VFR BUT THESE ARE EXPECTED TO DROP TO
MVFR IN LIGHT SNOW BEFORE SUNSET THIS EVENING. CEILINGS AND
VISIBILITY WILL CONTINUE TO DETERIORATE TONIGHT AS THE SYSTEM MOVES
THROUGH THE AREA SENDING CONDITIONS TO IFR WITH MOUNTAIN OBSCURATION
ACROSS KMYL AND KBKE AFTER 03Z. SURFACE WINDS WILL INCREASE TO 10 TO
15 KNOTS WITH THE APPROACH OF THE FRONT TONIGHT AND GET GUSTY 20 TO
30 KNOTS FROM THE WEST NORTHWEST WEDNESDAY MORNING BEHIND THE FRONT.
UPPER LEVEL WINDS ALSO INCREASING AS THE SYSTEM NEARS AND SEVERAL
AIRCRAFT ALREADY THIS MORNING REPORTING OCCASIONAL LGT TO MODERATE
TURBULENCE.
&&
.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&
$$
WEATHER.GOV/BOISE
SHORT TERM...SP
LONG TERM....GS/DG
AVIATION.....GS
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
229 PM CST TUE JAN 27 2009
.DISCUSSION...
1155 AM CST
DRY AIR NOTED IN MORNING RAOBS/ACARS SOUNDINGS CONTINUES TO ERODE
PER LATEST ACARS SOUNDINGS/VWP AS SYNOPTIC SCALE LIFT INCREASE IN
ADVANCE OF APPROACHING UPPER LEVEL TROUGH. A FEW AREAS OF MORE
ORGANIZED PRECIPITATION NOTED ON REGIONAL RADAR MOSAIC WITH
INCREASING ISENTROPIC LIFT ACROSS CENTRAL ILLINOIS...AND MORE IN
THE WAY OF MID LEVEL FRONTOGENETIC FORCING FROM EASTERN IOWA INTO
NORTH CENTRAL ILLINOIS. MAIN UPDATE TO THE FORECAST WAS TO ACCOUNT
FOR HIGHER POPS ALONG AND NORTH OF INTERSTATE 80 DUE TO THIS
ELEVATED FORCING. HAVE NOT MADE MANY CHANGES TO SNOW ACCUMULATIONS
THIS AFTERNOON...OTHER THAN TO NUDGE UP MINOR ACCUMULATIONS
ACROSS THE NORTH. IF FRONTOGENETIC FORCING DOES BECOME BETTER
ORGANIZED...MAY NEED TO FURTHER INCREASE POPS/SNOW ACCUMULATIONS
ACROSS FAR NORTHERN ILLINOIS THIS AFTERNOON.
MARSILI
&&
.PREV DISCUSSION...
417 AM CST
BRUNT OF LATEST WINTER STORM BYPASSING THE LOCAL AREA WELL TO THE
SOUTH AND EAST EARLY THIS MORNING. NO MAJOR FORECAST
CONCERNS...JUST POTENTIAL OF PERIODIC LIGHT SNOW EVENTS AS SHORT
WAVES MOVE THROUGH THE LONG WAVE TROF AS IT GRADUALLY MOVES FROM
THE WESTERN U.S. ACROSS CENTRAL NOAM...EVENTUALLY REACHING
EASTERN CANADA AND THE ATLANTIC COAST BY SAT. POTENTIAL SNOWFALL
FROM THIS AFTERNOON AND TONIGHT RANGES FROM A DUSTING NORTH
CENTRAL IL TO AROUND 3 INCHES IN FAR SOUTHEASTERN PORTION OF THE
FORECAST AREA.
LIGHT SNOW ON THE NORTHERN EDGE REACHED AS FAR NORTH AS BMI...DNV
AND LAF EARLIER DURING THE OVERNIGHT BUT WITH THE LEAD SHORT WAVE
CURRENTLY MOVING FROM EASTERN MO OVER SOUTHERN IL SATELLITE IR
LOOP SHOWS BACK EDGE OF THE LARGE COLD-TOPPED BAROCLINIC LEAF
ABOUT TO CROSS FROM CENTRAL AND SOUTHERN IL TO OVER IN.
CORRESPONDINGLY...RADAR COMPOSITE LOOP ALSO SHOWS NORTHERN/WESTERN
EDGE OF THE PRECIP SHIELD PULLING AWAY FROM THE REGION.
SATELLITE ALSO SHOWS A COMPACT MID-UPPER LOW HAS MOVED FROM EASTERN
SD INTO CENTRAL MN...WITH ANOTHER SHORT WAVE EJECTING FROM THE
WESTERN UPPER TROF OVER NORTHEAST CO AND SOUTHWEST NE. ONLY SOME
PATCHES OF MID CLOUDINESS UNDER/NEAR THE MN CIRCULATION AS DRY AIR
WITH THE SURFACE RIDGE IS IN PLACE ACROSS THE UPPER MS VALLEY.
WITH THE CO SHORT WAVE...A BAND OF LIGHT SNOW HAS BEEN STREAKING
FROM NORTHWEST KS ACROSS SOUTH CENTRAL AND SOUTHEAST NE INTO
SOUTHWEST IA WHILE FURTHER SOUTH IN NORTHEASTERN OK AND SOUTHEAST
KS A NASTY MIX OF THUNDER SNOW/SLEET/FREEZING RAIN IS OCCURRING.
THIS PRECIP TO REMAIN SOUTH OF THE AREA BUT AS THE COMBINATION OF
THE MN UPPER LOW AND THE CO SHORT WAVE CONTINUE EASTWARD TODAY AND
TONIGHT THE NORTHERN EDGE OF NEWLY DEVELOPING PRECIP AREA WILL
MOVE INTO THE AREA. LIGHT SNOW MAY GET AS FAR NORTH AS THE EASTERN
IL-WI STATE LINE DURING THE AFTERNOON...AND THEN PULL BACK AWAY
OVERNIGHT AS THE POSITIVE TILT UPPER TROF AXIS MOVES ACROSS WI AND
NORTHERN IL.
POTENTIAL FOR SOME ACCUMULATIONS BUT TOTALS EXPECTED TO BE
LIGHT...RANGING FROM A TENTH OF TWO FAR NORTHEAST IL UP TO 3
INCHES TOWARD THE DNV AND LAF AREAS.
BELOW NORMAL TEMPS PERSIST TODAY AND WED THEN MODERATE SOME ON THU
AS FLOW BACKS AHEAD OF A STRONG SHORT WAVE...CURRENTLY OVER THE
B.C. COAST...AS IT MOVES TO WESTERN ONTARIO AND THE UPPER GREAT
LAKES. COLD AIR RETURNS THU NIGHT AS THE SHORT WAVE...ITS
ASSOCIATED SURFACE LOW AND TRAILING COLD FRONT MOVE EAST. ANOTHER
SHORT WAVE...FURTHER UPSTREAM OVER THE ALEUTIANS...BRINGS MILDER
PACIFIC AIR ACROSS WESTERN CANADA AND THE ROCKIES AND EVENTUALLY
THE LOCAL AREA FOR THE WEEKEND WITH TEMPERATURES A BIT ABOVE
NORMAL.
TRS
&&
.AVIATION...
1220 PM CST
1800 UTC...MAIN AVIATION FORECAST CONCERN WILL CONTINUE TO CENTER
ON SNOW POTENTIAL THIS AFTERNOON INTO TONIGHT.
MID/UPPER LEVEL TROUGH WILL CONTINUE TO APPROACH NORTHERN
ILLINOIS/NORTHWEST INDIANA THROUGH TONIGHT. OVERRUNNING LIGHT SNOW
IS BEGINNING TO INCREASE ALTHOUGH AT 17Z SURFACE OBSERVATIONS INDICATE
NOT MUCH IN THE WAY OF PRECIPITATION REACHING THE GROUND.
EXPECTING OVER THE NEXT FEW HOURS...SNOW WILL BECOME MORE
WIDESPREAD ALTHOUGH REMAIN QUITE LIGHT. HAVE INTRODUCED SOME MVFR
VSBYS ACROSS TERMINALS FOR THIS AFTERNOON...ALTHOUGH SOME
LOCALIZED IFR VSBYS WILL BE POSSIBLE. CIGS SHOULD GENERALLY BE IN
THE 1500 TO 2500 FT RANGE IN ASSOCIATION WITH THE SNOW THIS
AFTERNOON. IT STILL APPEARS AS THOUGH THE MAIN SYNOPTIC SNOW WITH
THIS SYSTEM WILL AFFECT AREAS SOUTH OF THE TERMINALS...ALTHOUGH
SOME LIGHT SNOW WILL BE POSSIBLE TONIGHT ACROSS NORTHERN
ILLINOIS/NORTHWEST INDIANA. MAIN CHANGE TO THE 18Z TAFS WAS TO
EXPAND MENTION OF LIGHT SNOW INTO THE OVERNIGHT HOURS WITH
EXPECTATION THAT SOME LAKE INDUCED CONVERGENCE MAY KEEP SOME LAKE
EFFECT SNOW SHOWERS IN PLACE ACROSS NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...BUT CONFIDENCE IS LOW IN HOW FAR INLAND THESE
SNOW SHOWERS WILL AFFECT. BEST CHANCE OF SNOW AT RFD WILL LIKELY
BE THIS AFTERNOON IN ASSOCIATION WITH THE MID LEVEL FRONTOGENESIS
BAND...WITH MUCH OF THE LIGHT SNOW TONIGHT EXPECTED TO REMAIN TO
THE SOUTH AND EAST. NORTH WINDS 5 TO 15 KNOTS WILL CONTINUE
THROUGH TONIGHT EVENTUALLY BECOMING WEST WEDNESDAY AFTERNOON AS THE
LOW PRESSURE AREA TO THE SOUTH TRACKS INTO THE OHIO RIVER VALLEY
ALLOWING A RIDGE AXIS TO BUILD INTO NORTHWEST ILLINOIS.
MARSILI
&&
.MARINE...
225 PM CST
A RIDGE OF HIGH PRESSURE WILL CONTINUE TO INFLUENCE LAKE MICHIGAN
TONIGHT WITH RELATIVELY LIGHT WINDS THROUGH LATE TONIGHT. BY LATE
NIGHT...SFC LOW PRESSURE WILL BEGIN TO TRACK INTO THE OHIO RIVER
VALLEY AS A SFC RIDGE AXIS APPROACHES THE MISSISSIPPI RIVER. THIS
WILL RESULT IN NORTHWEST WINDS WEDNESDAY MORNING...BECOMING WEST
WEDNESDAY AFTERNOON. ANOTHER FAST MOVING STORM SYSTEM WILL
APPROACH THE WESTERN GREAT LAKES WEDNESDAY NIGHT WITH
STRENGTHENING SOUTHWEST WINDS EXPECTED IN ADVANCE OF THE TROUGH
ASSOCIATED WITH THIS SYSTEM. THIS SFC TROUGH IS EXPECTED TO TRACK
ACROSS LAKE MICHIGAN THURSDAY MORNING TAKING WINDS TO THE WEST.
THE INITIAL SFC TROUGH PASSAGE THURSDAY MORNING WILL TAKE WINDS
TO THE WEST FOLLOWED BY A COLD FRONT PASSAGE THURSDAY AFTERNOON
WITH SOME NORTHWEST GUSTS UP AROUND 25 KNOTS POSSIBLE. NORTHWEST
WINDS BEHIND THIS FRONT WILL BEGIN TO DIMINISH LATE FRIDAY AS NEXT
SFC HIGH BEGINS TO BUILD IN. THE MOST SIGNIFICANT STORM DURING
THIS FORECAST PERIOD SHOULD OCCUR FOR THE WEEKEND WITH BOTH
ECMWF/GFS INDICATING A 29.1 INCH LOW MOVING ACROSS ONTARIO. SOME
SOUTHWEST GALE GUSTS ARE POSSIBLE SATURDAY/SATURDAY NIGHT AND WILL
INCLUDE A MENTION OF GALES FOR SATURDAY.
MARSILI
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1223 PM CST TUE JAN 27 2009
.DISCUSSION...
1155 AM CST
DRY AIR NOTED IN MORNING RAOBS/ACARS SOUNDINGS CONTINUES TO ERODE
PER LATEST ACARS SOUNDINGS/VWP AS SYNOPTIC SCALE LIFT INCREASE IN
ADVANCE OF APPROACHING UPPER LEVEL TROUGH. A FEW AREAS OF MORE
ORGANIZED PRECIPITATION NOTED ON REGIONAL RADAR MOSAIC WITH
INCREASING ISENTROPIC LIFT ACROSS CENTRAL ILLINOIS...AND MORE IN
THE WAY OF MID LEVEL FRONTOGENETIC FORCING FROM EASTERN IOWA INTO
NORTH CENTRAL ILLINOIS. MAIN UPDATE TO THE FORECAST WAS TO ACCOUNT
FOR HIGHER POPS ALONG AND NORTH OF INTERSTATE 80 DUE TO THIS
ELEVATED FORCING. HAVE NOT MADE MANY CHANGES TO SNOW ACCUMULATIONS
THIS AFTERNOON...OTHER THAN TO NUDGE UP MINOR ACCUMULATIONS
ACROSS THE NORTH. IF FRONTOGENETIC FORCING DOES BECOME BETTER
ORGANIZED...MAY NEED TO FURTHER INCREASE POPS/SNOW ACCUMULATIONS
ACROSS FAR NORTHERN ILLINOIS THIS AFTERNOON.
MARSILI
&&
.PREV DISCUSSION...
417 AM CST
BRUNT OF LATEST WINTER STORM BYPASSING THE LOCAL AREA WELL TO THE
SOUTH AND EAST EARLY THIS MORNING. NO MAJOR FORECAST
CONCERNS...JUST POTENTIAL OF PERIODIC LIGHT SNOW EVENTS AS SHORT
WAVES MOVE THROUGH THE LONG WAVE TROF AS IT GRADUALLY MOVES FROM
THE WESTERN U.S. ACROSS CENTRAL NOAM...EVENTUALLY REACHING
EASTERN CANADA AND THE ATLANTIC COAST BY SAT. POTENTIAL SNOWFALL
FROM THIS AFTERNOON AND TONIGHT RANGES FROM A DUSTING NORTH
CENTRAL IL TO AROUND 3 INCHES IN FAR SOUTHEASTERN PORTION OF THE
FORECAST AREA.
LIGHT SNOW ON THE NORTHERN EDGE REACHED AS FAR NORTH AS BMI...DNV
AND LAF EARLIER DURING THE OVERNIGHT BUT WITH THE LEAD SHORT WAVE
CURRENTLY MOVING FROM EASTERN MO OVER SOUTHERN IL SATELLITE IR
LOOP SHOWS BACK EDGE OF THE LARGE COLD-TOPPED BAROCLINIC LEAF
ABOUT TO CROSS FROM CENTRAL AND SOUTHERN IL TO OVER IN.
CORRESPONDINGLY...RADAR COMPOSITE LOOP ALSO SHOWS NORTHERN/WESTERN
EDGE OF THE PRECIP SHIELD PULLING AWAY FROM THE REGION.
SATELLITE ALSO SHOWS A COMPACT MID-UPPER LOW HAS MOVED FROM EASTERN
SD INTO CENTRAL MN...WITH ANOTHER SHORT WAVE EJECTING FROM THE
WESTERN UPPER TROF OVER NORTHEAST CO AND SOUTHWEST NE. ONLY SOME
PATCHES OF MID CLOUDINESS UNDER/NEAR THE MN CIRCULATION AS DRY AIR
WITH THE SURFACE RIDGE IS IN PLACE ACROSS THE UPPER MS VALLEY.
WITH THE CO SHORT WAVE...A BAND OF LIGHT SNOW HAS BEEN STREAKING
FROM NORTHWEST KS ACROSS SOUTH CENTRAL AND SOUTHEAST NE INTO
SOUTHWEST IA WHILE FURTHER SOUTH IN NORTHEASTERN OK AND SOUTHEAST
KS A NASTY MIX OF THUNDER SNOW/SLEET/FREEZING RAIN IS OCCURRING.
THIS PRECIP TO REMAIN SOUTH OF THE AREA BUT AS THE COMBINATION OF
THE MN UPPER LOW AND THE CO SHORT WAVE CONTINUE EASTWARD TODAY AND
TONIGHT THE NORTHERN EDGE OF NEWLY DEVELOPING PRECIP AREA WILL
MOVE INTO THE AREA. LIGHT SNOW MAY GET AS FAR NORTH AS THE EASTERN
IL-WI STATE LINE DURING THE AFTERNOON...AND THEN PULL BACK AWAY
OVERNIGHT AS THE POSITIVE TILT UPPER TROF AXIS MOVES ACROSS WI AND
NORTHERN IL.
POTENTIAL FOR SOME ACCUMULATIONS BUT TOTALS EXPECTED TO BE
LIGHT...RANGING FROM A TENTH OF TWO FAR NORTHEAST IL UP TO 3
INCHES TOWARD THE DNV AND LAF AREAS.
BELOW NORMAL TEMPS PERSIST TODAY AND WED THEN MODERATE SOME ON THU
AS FLOW BACKS AHEAD OF A STRONG SHORT WAVE...CURRENTLY OVER THE
B.C. COAST...AS IT MOVES TO WESTERN ONTARIO AND THE UPPER GREAT
LAKES. COLD AIR RETURNS THU NIGHT AS THE SHORT WAVE...ITS
ASSOCIATED SURFACE LOW AND TRAILING COLD FRONT MOVE EAST. ANOTHER
SHORT WAVE...FURTHER UPSTREAM OVER THE ALEUTIANS...BRINGS MILDER
PACIFIC AIR ACROSS WESTERN CANADA AND THE ROCKIES AND EVENTUALLY
THE LOCAL AREA FOR THE WEEKEND WITH TEMPERATURES A BIT ABOVE
NORMAL.
TRS
&&
.AVIATION...
1220 PM CST
1800 UTC...MAIN AVIATION FORECAST CONCERN WILL CONTINUE TO CENTER
ON SNOW POTENTIAL THIS AFTERNOON INTO TONIGHT.
MID/UPPER LEVEL TROUGH WILL CONTINUE TO APPROACH NORTHERN
ILLINOIS/NORTHWEST INDIANA THROUGH TONIGHT. OVERRUNNING LIGHT SNOW
IS BEGINNING TO INCREASE ALTHOUGH AT 17Z SURFACE OBSERVATIONS INDICATE
NOT MUCH IN THE WAY OF PRECIPITATION REACHING THE GROUND.
EXPECTING OVER THE NEXT FEW HOURS...SNOW WILL BECOME MORE
WIDESPREAD ALTHOUGH REMAIN QUITE LIGHT. HAVE INTRODUCED SOME MVFR
VSBYS ACROSS TERMINALS FOR THIS AFTERNOON...ALTHOUGH SOME
LOCALIZED IFR VSBYS WILL BE POSSIBLE. CIGS SHOULD GENERALLY BE IN
THE 1500 TO 2500 FT RANGE IN ASSOCIATION WITH THE SNOW THIS
AFTERNOON. IT STILL APPEARS AS THOUGH THE MAIN SYNOPTIC SNOW WITH
THIS SYSTEM WILL AFFECT AREAS SOUTH OF THE TERMINALS...ALTHOUGH
SOME LIGHT SNOW WILL BE POSSIBLE TONIGHT ACROSS NORTHERN
ILLINOIS/NORTHWEST INDIANA. MAIN CHANGE TO THE 18Z TAFS WAS TO
EXPAND MENTION OF LIGHT SNOW INTO THE OVERNIGHT HOURS WITH
EXPECTATION THAT SOME LAKE INDUCED CONVERGENCE MAY KEEP SOME LAKE
EFFECT SNOW SHOWERS IN PLACE ACROSS NORTHEAST ILLINOIS AND
NORTHWEST INDIANA...BUT CONFIDENCE IS LOW IN HOW FAR INLAND THESE
SNOW SHOWERS WILL AFFECT. BEST CHANCE OF SNOW AT RFD WILL LIKELY
BE THIS AFTERNOON IN ASSOCIATION WITH THE MID LEVEL FRONTOGENESIS
BAND...WITH MUCH OF THE LIGHT SNOW TONIGHT EXPECTED TO REMAIN TO
THE SOUTH AND EAST. NORTH WINDS 5 TO 15 KNOTS WILL CONTINUE
THROUGH TONIGHT EVENTUALLY BECOMING WEST WEDNESDAY AFTERNOON AS THE
LOW PRESSURE AREA TO THE SOUTH TRACKS INTO THE OHIO RIVER VALLEY
ALLOWING A RIDGE AXIS TO BUILD INTO NORTHWEST ILLINOIS.
MARSILI
&&
.MARINE...
314 AM CST
THE LARGE HIGH OVER EASTERN NEBRASKA WILL MOVE SOUTH DURING THE
NEXT 24 HOURS. TODAY...THE WIND WILL BECOME SOUTHWEST 5 TO 10
KNOTS IN THE NORTH HALF OF LAKE MICHIGAN AND NORTH 10 TO 15 KNOTS
IN THE SOUTH HALF OF LAKE MICHIGAN. THE WAVES WILL SUBSIDE TO 1
FOOT OR LESS TONIGHT. THE HIGH WILL BE THE SOUTHERN END OF A RIDGE
THAT WILL EXTEND TO SOUTHWEST QUEBEC BY WEDNESDAY MORNING. A LOW
WILL MOVE INTO NORTHERN LAKE SUPERIOR LATE WEDNESDAY NIGHT. THE
WIND WILL BE SOUTHWEST AT 10 TO 20 KNOTS WEDNESDAY NIGHT. AS THE
LOW MOVES EAST TO SOUTHWEST QUEBEC BY FRIDAY MORNING...THE WIND
BECOMES NORTHEAST AT 10 TO 20 KNOTS BY FRIDAY MORNING.
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
945 PM EST TUE JAN 27 2009
.UPDATE...
01Z SFC MAP SHOWS THE 1014MB SFC LOW ACROSS NE MS WHICH IS A BIT
FURTHER NW THAN THE GFS/NAM HAD INDICATED ALTHOUGH NOT SIGNIFICANTLY
SO. PROFILERS SHOW 25-40KT LLJ STILL TARGETING SOUTHERN IN IN
RESPONSE TO THE INCREASING UPWARD MOTION AHEAD OF THE UPPER WAVE THE
COUPLED UPPER JET STRUCTURE ACROSS THE REGION. STRONGEST 3HR
PRESSURE FALLS ARE NOW OCCURRING ACROSS SE OH SO THE SFC LOW SHOULD
CONTINUE TO TRACK ACROSS CENTRAL TN AND EASTERN KY OVERNIGHT. WE
HAVE BEEN FOLLOWING THE SNOW/SLEET LINE AND THE SLEET/FREEZING RAIN
LINE MOST OF THE NIGHT AND OBS...REPORTS AND AIRCRAFT SOUNDINGS
SUGGEST THAT THIS LINE HAS MOVED AS FAR NORTH AS IT SHOULD GET
TONIGHT WITH SLEET JUST SOUTH OF IND AND SLEET/FREEZING RAIN
OCCURRING ALONG OR SOUTH OF A SULLIVAN INTO SOUTHERN MORGAN/JOHNSON
COUNTIES AND SOUTH OF SHELBYVILLE. GIVEN AMOUNT OF LIFT/MOISTURE AND
RADAR TRENDS WE HAVE RAISED THE ICE ACCUMULATION TO AROUND ONE HALF
INCH ACROSS THE SOUTH WHERE THE ICE ACCUMULATION SHOULD PERSIST
THROUGH 06Z BEFORE CHANGING TO SLEET/SNOW IN THE 6Z TO 9Z PERIOD.
MEANWHILE...ACROSS THE I-70 CORRIDOR AND POINTS NORTH...NATIONAL
RADAR IS SHOWING THE MAIN PRECIP SHIELD WITH THE UPPER WAVE NOW
APPROACHING THE CWA. RETURNS HAVE TAKEN ON A BANDED STRUCTURE ACROSS
IL WHERE VIS HAVE FALLEN TO AROUND OR JUST BELOW 1 MILE. THE 18Z
GFS/NAM KEPT THE LAYERED FRONTOGENETICAL FORCING SOUTH OF I-70
OVERNIGHT SO IT APPEARS THAT THIS FORCING IS OCCURRING SOMEWHAT
NORTH OF THE MODELS FCST. GIVEN THE AIR TEMPS IN THE TEENS SNOW
RATIOS WILL BE IN THE 15:1 RANGE WHICH SUGGESTS THAT ONE QUARTER
INCH OF LIQUID COULD RESULT IN UPWARDS OF 4-5 INCHES OF SNOW. THEY
ALREADY HAVE REPORTED 1 TO 2 INCHES OF SNOW AROUND THE LAF AREA AND
EXPECT MOST SPOTS ESPECIALLY SE OF LAF TO RECEIVE ANYWHERE FROM 4-5
INCHES AROUND OR N OF LAF TO PERHAPS AS MUCH AS 6-8 INCHES ACROSS
BOONE COUNTY BY WEDS AM SO WE WILL UPGRADE A FEW MORE COUNTIES NW OF
INDIANAPOLIS INTO A WARNING FOR SNOW AMOUNTS. NO SIG CHANGES TO SNOW
AMOUNTS FOR THE IND METRO AREA WHERE 3 INCHES HAVE ALREADY FALLEN
AND ANOTHER 3 TO 5 INCHES SHOULD FALL OVERNIGHT WHICH ADDS UP TO 6
TO 8 INCHES WITH SOME HIGHER AMOUNTS LIKELY FOR THE STORM BY EARLY
WEDS.
&&
.AVIATION...DISCUSSION FOR 00Z TAFS.
AT KBMG EXPECT SLEET TO CHANGE OVER TO SNOW OVR THE NEXT COUPLE OF
HOURS. AT ALL SITES EXPECT SNOW TO CONTINUE THRU THE MORNING. CONDS
AT KLAF SHUD NOT DROP AS MUCH. WITH BEST FORCING STAYING TO THE S OF
THERE EXPECT CONDS OVERALL TO BE A BIT BETTER WITH VSBYS STAYING
MVFR MOST OF THE TIME AND CIGS BOUNCING BETWEEN MVFR AND IFR.
LOOKING AT SOUNDINGS AND TIME HTS FOR KIND...SATURATION CONTS THRU
17Z. BEST FORCING ENDS BEFORE THEN...BUT WITH STRONG FORCING
CONTINUING THRU AT LEAST 12Z. EXPECT CIGS TO JUMP AROUND BETWEEN
MVFR AND IFR OR LOWER BASED ON CURRENT OBS AND EXPECTED CONDS. WITH
GREAT FORCING FOR SNOW THRU THE NIGHT COULD SEE VSBYS STAY AROUND
1SM OR LESS FOR MOST OF THE NIGHT. MIGHT SEE THEM JUMP AROUND A
LITTLE AS WELL BUT WITH THE GREAT FORCING AND AMPLE MOISTURE WILL
PLAY IT PESSIMISTIC AND KEEP 1SM MOST OF THE NIGHT WITH A TEMPO OF
1/2 FOR A TIME. HEAVIER SNOW SHUD SET UP IN BANDS BASED ON
INSTABILITY SO WL INCLUDE AS A TEMPO AT ALL SITES BUT KLAF. KBMG
SHUD SEE SIMILAR CONDS TO KIND ONCE PTYPE SWITCHES OVER TO SNOW.
KHUF WILL BE SIMILAR EARLY BUT WILL IMPROVE BEFORE KIND DOES.
&&
.SHORT TERM.../TONIGHT INTO THURSDAY/
FORECAST FOCUS IS ON WINTER STORM.
AT 19Z MAIN UPPER TROF WAS ACROSS SWRN USA. INVERTED TROF EXTENDED
FM LOUISIANA INTO KY. SNOW WAS ACROSS NRN FA AND FZRA AND SNOW WAS
ACROSS SRN FA.
MODELS HAVE COME INTO BETTER AGREEMENT THIS RUN. WITH NO REAL
FRONTRUNNER...USED A BLEND OF THE SIMILAR SOLUTIONS.
NEAR 100 POPS TONIGHT AS FORCING AND MOISTURE WILL CONTINUE PRECIP.
UPPER AIR PROGS SHOW PLENTY OF MOISTURE NOT TOO FAR TO THE S OF
THE FA AND WATER VAPOR SATELLITE SHOWS SOME FEED FROM THE BAJA
AREA AS WELL. THERE WILL BE FRONTOGENETICAL FORCING TONIGHT WHICH
COULD CREATE BANDING. ALSO...HINTS OF SLANTWISE CONVECTION AS
WELL. UPPER JET WILL ADD TO LIFT. NOT COMPLETELY CONFIDENT IN THE
HIGH QPF GENERATED BY THE MODELS THOUGH...EVEN WITH THE MOISTURE
CONNECTIONS MENTIONED ABOVE. BEST MOISTURE TRANSPORT IS TO THE S
AND E OF THE FA. THUS WILL NOT GO QUITE AS HIGH AS MODEL QPF. EVEN
CUTTING MODEL QPF YIELDS ENOUGH SNOW FOR AN AVERAGE OF 6 INCH
SNOWS ALONG THE I-70 CORRIDOR NE INTO MUNCIE AREA. WILL EXPAND THE
WARNING N TO THESE AREAS. HIGHER AMOUNTS WILL OCCUR...ESPECIALLY
IN AREAS WHERE BANDING SETS UP. ACROSS SRN FA SNOW AMOUNTS MAY
NOT BE AS HIGH DUE TO PRECIP MIXING WITH SLEET AND FREEZING RAIN.
FOR NOW HAVE NOT INCLUDED TOO MUCH FREEZING RAIN PER MODEL
SOUNDINGS AND PRECIP CHANGING BACK TO SNOW ACROSS PARTS OF SRN IL.
WILL HAVE TO WATCH CLOSELY THOUGH. MAV TEMPS LOOK REASONABLE FOR
LOWS GIVEN EXPECTED CONDITIONS.
MODELS HINTING AT DEFORMATION ZONE EARLY ON WED WHICH WOULD LEAD
TO ANOTHER INCH OR SO BEFORE SNOW TAPERS OFF. KEEPING THE
WARNING/ADVISORY IN EFFECT UNTIL NOON STILL LOOKS OK. MAV TEMPS
LOOK GOOD AGAIN.
WEAK WAVE WILL BRING A SMALL CHANCE FOR SNOW AGAIN BY THU.
&&
.LONG TERM.../THURSDAY THROUGH MONDAY/
AS FOR THE EXTENDED...
LITTLE CHANGE IN THE EXTENDED AS THE ECMWF AND GFS AGREE THAT THE
COLD NW UPPER FLOW SHALL PERSIST. THE MODELS REMAIN CONSISTANT WITH
A WEAK TROUGH PUSHING ACRS THE RGN ON THURSDAY NIGHT AND
FRIDAY...THEN AGAIN ON SUNDAY NIGHT INTO MONDAY. BOTH SYSTEMS APPEAR
RATHER WEAK WITH SUSPECT MOISTURE AVAILABLE WITH THE THURSDAY
NIGHT/FRIDAY SYSTEM AND BETTER MOISTURE WITH THE SECOND SYSTEM BUT
WEAKER DYNAMICS.
CONTINUED THE TREND OF HIGHS AND LOW GENERALLY A FEW DEGREES BELOW
MEXMOS AS EXPECTED SNOW COVER AND COLD NW FLOW SHUD HAPMER MUCH IN
TEMPERATURE RISES.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 12 PM EST WEDNESDAY FOR INZ030-
036>049-051>057-060>065-067>072.
WINTER WEATHER ADVISORY UNTIL 12 PM EST WEDNESDAY FOR INZ021-028-
029-031-035.
&&
$$
UPDATE...CO
SHORT TERM...CS
LONG TERM...JP
AVIATION...CP
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
913 PM EST TUE JAN 27 2009
MESO AFD 3
THINGS ARE PROCEEDING ABOUT AS EXPECTED...SO NO MAJOR CHANGES TO THE
FORECAST. TWEAKED THE GRIDS TO MORE CLOSELY REFLECT REALITY AND
BROUGHT PLAIN RAIN FARTHER NORTH OVERNIGHT...BUT KEPT THE BASIC
ELEMENTS OF THE OVERALL FORECAST THE SAME. DESPITE PLAIN RAIN
PROBABLY MAKING IT AS FAR NORTH AS THE OHIO RIVER OVERNIGHT...NO
CHANGES TO THE HEADLINES AS COLD AIR SWEEPS IN EARLY WEDNESDAY
MORNING AND BRINGS AN UGLY WINTRY MIX AND THEN MODERATE TO POSSIBLY
BRIEFLY HEAVY SNOW AROUND COMMUTE TIME ESPECIALLY IN THE LOUISVILLE
METRO REGION.
MESO AFD 2
WELL...LATEST ACARS SOUNDING DENOTES WARM NOSE THAT IS SO DEEP THAT
IT IS DOMINATING THE ARCTIC LAYER. THE AIRCRAFT OBSERVED +6C TEMP
AT 4400FT...WITH A FZL AT 2650 FT. ON OUTDOOR AREAS THAT ARE ALREADY
FROZEN...THE FALLING PRECIP IS ACCRETING...ON AREAS THAT ARE
LIQUID...IT WILL CONTINUE TO BE LIQUID. TREES AND POWER LINES ARE
BECOMING HEAVY FROM THE WEIGHT OF THE ICE...AND WE SUSPECT THERE
WILL BE AN INCREASE IN NUMBERS OF SNAPPED TREES...AND DOWNED POWER
LINES. RAINFALL AMOUNTS OF UP TO 1/10 PER HOUR ARE POSSIBLE.
THE GREATEST THREAT OF SURFACE ACCRETION ICE WILL BE ALONG AND NORTH
OF THE BLUE GRASS PARKWAY...WITH PEAK ACRS SRN IN AND TRIMBLE
COUNTIES. PORTIONS OF SRN INDIANA WILL ALSO HAVE A MIX OF SLEET WITH
THE FZRA. THE 00Z BNA SOUNDING GOES UP TO +12C AT 3000 FT AND IS
ALL ABOVE FREEZING. SOUTH OF THE BLUE GRASS PARKWAY WILL HAVE LIQUID
RAIN UNTIL 10-12Z WHEN THE COLD AIR IS USHERED IN FROM NW TO SE.
THE FZRA WILL QUICKLY SWITCH TO SNOW AFTER PERHAPS A <1 HR PERIOD OF
FZRA AND IP BEFORE SWITCHING TO ALL SNOW. SNOW AMOUNTS FOR WED AM
APPEAR TO BE GOOD. ANOTHER BAD MORNING COMMUTE ON WEDNESDAY!
PREV DISCUSSION....635 PM TUE JAN 27 2009
MESO AFD 1
WELL...DEEP TROPOSPHERIC MOISTURE IS ENSCONCED ACROSS THE CWA. THE
MOISTURE CHANNEL EXTENDS FROM PINEAPPLE CONNECTION FROM SW OF BAJA
CA. PWATS ARE EXTREMELY HIGH WITH 3/4 TO NEARLY 1 INCH...WHICH IS
OVER 200% OF CLIMATOLOGICAL NORMAL. THE 32 DEGREE ISOTHERM STRETCHES
FROM RUSSELLVILLE TO HODGENVILLE TO RICHMOND. THIS LINE HAS BEEN
CREEPING NORTHWARD ACROSS TIGHT BAROCLINIC ZONE TO THE NORTH. A
2050Z ACARS SOUNDING CONTINUES TO SHOW CLASSIC NASTY FZRA SOUNDING
WITH A MAX WARMTH OF +4C IN THE WARM LAYER...WHICH INCLUDES 5000 FT
OF ABOVE ZERO AIR. SFC TEMPS SHOULD WARM ANOTHER 1 TO 3 DEGREES
WITH A SW 50 KT LLVL JET.
WE HAVE BEEN RECEIVING A FEW MORE SLEET REPORTS...AND WE WILL BE
CHECKING ON THAT ANGLE. AN ACARS PLANE TAKING OFF OUT OF CVG SHOWED
A SLEET SOUNDING AT 21Z WHICH HAPPENS TO BE WHAT THEY ARE REPORTING
AT CVG. THE RUC IS SHOWING DEFINITIVE WARM NOSE OF ABV FREEZING AIR
THROUGH 06Z WITH A +2 TO + 4 AIR TEMP IN THE WARM SECTOR. WE EXPECT
ICE ACCUMULATIONS OF A TENTH OF AN INCH PER HOUR IN SOME AREAS.
PREVIOUS DISCUSSION...334 PM TUE JAN 27 2009
.SHORT TERM (TONIGHT AND TOMORROW)...
...SIGNIFICANT WINTER STORM THROUGH EARLY WEDNESDAY AFTERNOON...
ON THE NATIONAL RADAR WE HAVE WINTRY PRECIP STRETCHING FROM THE
PANHANDLE OF TEXAS TO VIRGINIA. THIS AREA OF PRECIP HAS CAUSED
NEARLY CONTINUOUS PRECIP OVER OUR FORECAST AREA (FA) TODAY.
SOUTHERN KY HAS BEEN MOSTLY RAIN THIS AFTERNOON WITH SURFACE TEMPS
HOVERING JUST ABOVE FREEZING HELPING TO IMPROVE THE ICY CONDITIONS
EXPERIENCED EARLIER. HOWEVER...CENTRAL KY...NORTHERN KY...AND
SOUTHERN INDIANA HAVE BEEN PRIMARILY FREEZING RAIN MOST OF THE
AFTERNOON WITH ICE ACCUMULATIONS AROUND A QUARTER OF AN INCH WITH
LOCALLY HIGHER AMOUNTS.
FOR THIS FORECAST PACKAGE...HAVE SIDED WITH 12Z NAM/9Z SREF BLEND
FOR QPF. RELIED ON 12Z ETA BUFKIT SOUNDINGS FOR PRECIP TYPE AND
CHANGE OVER.
TIMING...LIGHT PRECIP WILL CONTINUE WITH AN AREA OF STRONGER
PRECIP ARRIVING AS EARLY AS 3Z IN THE WESTERN FA AND EXITING THE
EASTERN FA NEAR 18Z TOMORROW. OVERNIGHT...EXPECT THE WINTRY
MIX...PRIMARILY FREEZING RAIN...TO CONTINUE OVER SOUTHERN
INDIANA...NORTHERN KY...AND CENTRAL KY THROUGH 8Z. AFTER 8Z...A
CHANGE OVER TO ALL SNOW WILL BEGIN FROM NW TO SE. OVER SOUTHERN
KY...PLAIN RAIN WILL DOMINATE MOST OF THE OVERNIGHT
HOURS...TRANSITION TO A BRIEF MIX...AND QUICKLY TO SNOW BY 12Z TO
14Z. SNOW WILL BE LIGHT TO MODERATE FROM 12Z THROUGH 18Z BEFORE
TAPER OFF OR ENDING AFTER 18Z TOMORROW.
PRECIP TYPE...EXPECT MAJOR POSSIBLY DEVASTATING ICING OVER SOUTHERN
INDIANA TONIGHT. ICE ACCUMULATIONS WILL TOP OUT AROUND 1 INCH IN
SOUTHERN INDIANA. LESSER ACCUMULATIONS WILL OCCUR OVER NORTHERN KY
AND CENTRAL KY...BUT THESE AREAS WILL STILL BE VERY HAZARDOUS.
AFTER THE PRECIP CHANGES OVER TO SNOW...THERE WILL STILL BE
SIGNIFICANT MOISTURE LEFT BEHIND FOR AS MUCH AS 5 OR 6 INCHES OF
SNOW OVER SOUTHERN INDIANA TO 1 INCH OF SNOW OVER SOUTHERN KY BY 18Z
TOMORROW. FOR MORE SPECIFIC GRAPHICAL INFORMATION...PLEASE REFER TO
OUR WEBSITE WEATHER.GOV/LMK.
AS A RESULT...WILL BE EXTENDING THE WINTER STORM WARNING THROUGH 18Z
TOMORROW AND ISSUING AN ADVY FOR SOUTHERN KY FROM 9Z TONIGHT THROUGH
18Z TOMORROW.
.LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)...
STORM SYSTEM WILL HAVE FINALLY DEPARTED BY WED EVENING...ALTHOUGH
SHALLOW BUT COLD LOW-LEVEL MOISTURE FCST TO REMAIN...SO STILL COULD
SEE SOME SNOW FLURRIES OR A FEW SNOW SHOWERS ESPECIALLY OVER NRN AND
ERN COUNTIES WED NIGHT.
ALL MODELS SHOW SOME AMPLIFICATION IN UPPER AIR PATTERN BY END OF
THE WEEK AS SHORTWAVE ENERGY DROPS SEWD INTO OH VALLEY. SOME MODEL
DIFFERENCES AS TO AMOUNT OF MOISTURE AVAILABILITY WITH THIS SYSTEM
BUT THERE IS SOME AGREEMENT THAT SOME MOISTURE BELOW 700 MB WILL BE
PRESENT ALONG WITH QUITE COLD AIR IN THE MOIST COLUMN TO GENERATE
SNOW SHOWERS ACROSS THE ENTIRE FCST AREA...WITH THE BEST CHANCES
OVER SOUTHERN IND AND N-CNTRL AND E-CNTRL KY. GIVEN THE COLD AIR
MASS... SNOW SHOWERS COULD PRODUCE A SMALL ACCUMULATION...BUT WILL
NOT BE A MAJOR SYSTEM. HIGHS ON FRI WILL PROBABLY ONLY BE IN THE
LOWER 20S NORTH TO MID TO PERHAPS UPR 20S FAR SOUTH ACROSS FCST AREA
(A LITTLE BELOW GUIDANCE).
AS UPPER TROF PULLS OFF TO THE EAST...MILDER AIR WILL ARRIVE BY
SUNDAY WITH HIGHS IN THE UPR 30S AND LOWER 40S. MODELS SHOW THE NEXT
WEATHER SYSTEM TO AFFECT OH VALLEY AROUND MONDAY TIME FRAME. GFS
AND ECMWF ARE TRYING TO SUGGEST SOME PHASING POTENTIAL WITH A SRN
STREAM SYSTEM WITH A DIGGING NRN STREAM SHORTWAVE TOWARD THE OH
VALLEY. HOWEVER...HOW TWO SHORTWAVES MAY INTERACT (IF AT ALL) AT
THIS TIME FRAME IS VERY DIFFICULT TO DIAGNOSE. RIGHT NOW...LOOKS
LIKE THIS SYSTEM COULD PRODUCE SOME RAIN SHOWERS AHEAD OF A COLD
FRONT ASSOCIATED WITH NRN STREAM SYSTEM...POSSIBLY TRANSITIONING TO
POST-FRONTAL SNOW SHOWERS. GIVEN UNCERTAINTY AT THIS TIME RANGE...
RAIN OR SNOW SHOWERS PLACED IN GRIDS SUNDAY NIGHT AND MONDAY.
&&
.AVIATION (00Z TAFS)...
IFR CONDITIONS PREVAIL AT ALL 3 SITES THRU 12Z...WITH FZRA AT LEX
AND SDF AND LIQUID RAIN AT BWG THROUGH 12Z OR SO. COLD AIR
ADVECTION THROUGHOUT THE ENTIRE TROPOSPHERE CHANGES PCPN TO ALL SN
AROUND 12Z. THE SNOW WILL LAST ABOUT 5 HOURS...WITH PERHAPS A
SCATTERED SNOW SHOWER IN THE AFTN MAINLY AT LEX...BUT MVFR CIGS AND
VSBYS WILL PREVAIL BY 18Z AND H8 THERMAL TROUGH TO OUR WEST WILL
KEEP LOW CLOUDS IN AT SDF THROUGH AT LEAST THE MID AFTN...AND THEN
SOME HIGH MID DECK CLOUDS WILL BE ALL THAT IS LEFT BY 00Z THU.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...WINTER STORM WARNING UNTIL 1 PM EST /12 PM CST/ WEDNESDAY FOR
KYZ023>043-045>049-053>057.
WINTER WEATHER ADVISORY FROM 4 AM EST /3 AM CST/ TO 1 PM EST /12
PM CST/ WEDNESDAY FOR KYZ061>067-070>078-081-082.
IN...WINTER STORM WARNING UNTIL 1 PM EST /12 PM CST/ WEDNESDAY FOR
INZ076>079-083-084-089>092.
&&
$$
MESO 3...13
MESO 1 AND 2...JDG
SHORT TERM...AML
LONG TERM....TWF
AVIATION.....JDG/TAR
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
730 PM EST TUE JAN 27 2009
MESO AFD
WELL...LATEST ACARS SOUNDING DENOTES WARM NOSE THAT IS SO DEEP THAT
IT IS DOMINATING THE ARCTIC LAYER. THE AIRCRAFT OBSERVED +6C TEMP
AT 4400FT...WITH A FZL AT 2650 FT. ON OUTDOOR AREAS THAT ARE ALREADY
FROZEN...THE FALLING PRECIP IS ACCRETING...ON AREAS THAT ARE
LIQUID...IT WILL CONTINUE TO BE LIQUID. TREES AND POWER LINES ARE
BECOMING HEAVY FROM THE WEIGHT OF THE ICE...AND WE SUSPECT THERE
WILL BE AN INCREASE IN NUMBERS OF SNAPPED TREES...AND DOWNED POWER
LINES. RAINFALL AMOUNTS OF UP TO 1/10 PER HOUR ARE POSSIBLE.
THE GREATEST THREAT OF SURFACE ACCRETION ICE WILL BE ALONG AND NORTH
OF THE BLUE GRASS PARKWAY...WITH PEAK ACRS SRN IN AND TRIMBLE
COUNTIES. PORTIONS OF SRN INDIANA WILL ALSO HAVE A MIX OF SLEET WITH
THE FZRA. THE 00Z BNA SOUNDING GOES UP TO +12C AT 3000 FT AND IS
ALL ABOVE FREEZING. SOUTH OF THE BLUE GRASS PARKWAY WILL HAVE LIQUID
RAIN UNTIL 10-12Z WHEN THE COLD AIR IS USHERED IN FROM NW TO SE.
THE FZRA WILL QUICKLY SWITCH TO SNOW AFTER PERHAPS A <1 HR PERIOD OF
FZRA AND IP BEFORE SWITCHING TO ALL SNOW. SNOW AMOUNTS FOR WED AM
APPEAR TO BE GOOD. ANOTHER BAD MORNING COMMUTE ON WEDNESDAY!
PREV DISCUSSION....635 PM TUE JAN 27 2009
MESO AFD 1
WELL...DEEP TROPOSPHERIC MOISTURE IS ENSCONCED ACROSS THE CWA. THE
MOISTURE CHANNEL EXTENDS FROM PINEAPPLE CONNECTION FROM SW OF BAJA
CA. PWATS ARE EXTREMELY HIGH WITH 3/4 TO NEARLY 1 INCH...WHICH IS
OVER 200% OF CLIMATOLOGICAL NORMAL. THE 32 DEGREE ISOTHERM STRETCHES
FROM RUSSELLVILLE TO HODGENVILLE TO RICHMOND. THIS LINE HAS BEEN
CREEPING NORTHWARD ACROSS TIGHT BAROCLINIC ZONE TO THE NORTH. A
2050Z ACARS SOUNDING CONTINUES TO SHOW CLASSIC NASTY FZRA SOUNDING
WITH A MAX WARMTH OF +4C IN THE WARM LAYER...WHICH INCLUDES 5000 FT
OF ABOVE ZERO AIR. SFC TEMPS SHOULD WARM ANOTHER 1 TO 3 DEGREES
WITH A SW 50 KT LLVL JET.
WE HAVE BEEN RECEIVING A FEW MORE SLEET REPORTS...AND WE WILL BE
CHECKING ON THAT ANGLE. AN ACARS PLANE TAKING OFF OUT OF CVG SHOWED
A SLEET SOUNDING AT 21Z WHICH HAPPENS TO BE WHAT THEY ARE REPORTING
AT CVG. THE RUC IS SHOWING DEFINITIVE WARM NOSE OF ABV FREEZING AIR
THROUGH 06Z WITH A +2 TO + 4 AIR TEMP IN THE WARM SECTOR. WE EXPECT
ICE ACCUMULATIONS OF A TENTH OF AN INCH PER HOUR IN SOME AREAS.
PREVIOUS DISCUSSION...334 PM TUE JAN 27 2009
.SHORT TERM (TONIGHT AND TOMORROW)...
...SIGNIFICANT WINTER STORM THROUGH EARLY WEDNESDAY AFTERNOON...
ON THE NATIONAL RADAR WE HAVE WINTRY PRECIP STRETCHING FROM THE
PANHANDLE OF TEXAS TO VIRGINIA. THIS AREA OF PRECIP HAS CAUSED
NEARLY CONTINUOUS PRECIP OVER OUR FORECAST AREA (FA) TODAY.
SOUTHERN KY HAS BEEN MOSTLY RAIN THIS AFTERNOON WITH SURFACE TEMPS
HOVERING JUST ABOVE FREEZING HELPING TO IMPROVE THE ICY CONDITIONS
EXPERIENCED EARLIER. HOWEVER...CENTRAL KY...NORTHERN KY...AND
SOUTHERN INDIANA HAVE BEEN PRIMARILY FREEZING RAIN MOST OF THE
AFTERNOON WITH ICE ACCUMULATIONS AROUND A QUARTER OF AN INCH WITH
LOCALLY HIGHER AMOUNTS.
FOR THIS FORECAST PACKAGE...HAVE SIDED WITH 12Z NAM/9Z SREF BLEND
FOR QPF. RELIED ON 12Z ETA BUFKIT SOUNDINGS FOR PRECIP TYPE AND
CHANGE OVER.
TIMING...LIGHT PRECIP WILL CONTINUE WITH AN AREA OF STRONGER
PRECIP ARRIVING AS EARLY AS 3Z IN THE WESTERN FA AND EXITING THE
EASTERN FA NEAR 18Z TOMORROW. OVERNIGHT...EXPECT THE WINTRY
MIX...PRIMARILY FREEZING RAIN...TO CONTINUE OVER SOUTHERN
INDIANA...NORTHERN KY...AND CENTRAL KY THROUGH 8Z. AFTER 8Z...A
CHANGE OVER TO ALL SNOW WILL BEGIN FROM NW TO SE. OVER SOUTHERN
KY...PLAIN RAIN WILL DOMINATE MOST OF THE OVERNIGHT
HOURS...TRANSITION TO A BRIEF MIX...AND QUICKLY TO SNOW BY 12Z TO
14Z. SNOW WILL BE LIGHT TO MODERATE FROM 12Z THROUGH 18Z BEFORE
TAPER OFF OR ENDING AFTER 18Z TOMORROW.
PRECIP TYPE...EXPECT MAJOR POSSIBLY DEVASTATING ICING OVER SOUTHERN
INDIANA TONIGHT. ICE ACCUMULATIONS WILL TOP OUT AROUND 1 INCH IN
SOUTHERN INDIANA. LESSER ACCUMULATIONS WILL OCCUR OVER NORTHERN KY
AND CENTRAL KY...BUT THESE AREAS WILL STILL BE VERY HAZARDOUS.
AFTER THE PRECIP CHANGES OVER TO SNOW...THERE WILL STILL BE
SIGNIFICANT MOISTURE LEFT BEHIND FOR AS MUCH AS 5 OR 6 INCHES OF
SNOW OVER SOUTHERN INDIANA TO 1 INCH OF SNOW OVER SOUTHERN KY BY 18Z
TOMORROW. FOR MORE SPECIFIC GRAPHICAL INFORMATION...PLEASE REFER TO
OUR WEBSITE WEATHER.GOV/LMK.
AS A RESULT...WILL BE EXTENDING THE WINTER STORM WARNING THROUGH 18Z
TOMORROW AND ISSUING AN ADVY FOR SOUTHERN KY FROM 9Z TONIGHT THROUGH
18Z TOMORROW.
.LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)...
STORM SYSTEM WILL HAVE FINALLY DEPARTED BY WED EVENING...ALTHOUGH
SHALLOW BUT COLD LOW-LEVEL MOISTURE FCST TO REMAIN...SO STILL COULD
SEE SOME SNOW FLURRIES OR A FEW SNOW SHOWERS ESPECIALLY OVER NRN AND
ERN COUNTIES WED NIGHT.
ALL MODELS SHOW SOME AMPLIFICATION IN UPPER AIR PATTERN BY END OF
THE WEEK AS SHORTWAVE ENERGY DROPS SEWD INTO OH VALLEY. SOME MODEL
DIFFERENCES AS TO AMOUNT OF MOISTURE AVAILABILITY WITH THIS SYSTEM
BUT THERE IS SOME AGREEMENT THAT SOME MOISTURE BELOW 700 MB WILL BE
PRESENT ALONG WITH QUITE COLD AIR IN THE MOIST COLUMN TO GENERATE
SNOW SHOWERS ACROSS THE ENTIRE FCST AREA...WITH THE BEST CHANCES
OVER SOUTHERN IND AND N-CNTRL AND E-CNTRL KY. GIVEN THE COLD AIR
MASS... SNOW SHOWERS COULD PRODUCE A SMALL ACCUMULATION...BUT WILL
NOT BE A MAJOR SYSTEM. HIGHS ON FRI WILL PROBABLY ONLY BE IN THE
LOWER 20S NORTH TO MID TO PERHAPS UPR 20S FAR SOUTH ACROSS FCST AREA
(A LITTLE BELOW GUIDANCE).
AS UPPER TROF PULLS OFF TO THE EAST...MILDER AIR WILL ARRIVE BY
SUNDAY WITH HIGHS IN THE UPR 30S AND LOWER 40S. MODELS SHOW THE NEXT
WEATHER SYSTEM TO AFFECT OH VALLEY AROUND MONDAY TIME FRAME. GFS
AND ECMWF ARE TRYING TO SUGGEST SOME PHASING POTENTIAL WITH A SRN
STREAM SYSTEM WITH A DIGGING NRN STREAM SHORTWAVE TOWARD THE OH
VALLEY. HOWEVER...HOW TWO SHORTWAVES MAY INTERACT (IF AT ALL) AT
THIS TIME FRAME IS VERY DIFFICULT TO DIAGNOSE. RIGHT NOW...LOOKS
LIKE THIS SYSTEM COULD PRODUCE SOME RAIN SHOWERS AHEAD OF A COLD
FRONT ASSOCIATED WITH NRN STREAM SYSTEM...POSSIBLY TRANSITIONING TO
POST-FRONTAL SNOW SHOWERS. GIVEN UNCERTAINTY AT THIS TIME RANGE...
RAIN OR SNOW SHOWERS PLACED IN GRIDS SUNDAY NIGHT AND MONDAY.
&&
.AVIATION (18Z TAFS)...
IFR CONDITIONS PREVAIL AT ALL 3 SITES THRU 12Z...WITH FZRA AT LEX AND
SDF AND LIQUID RAIN AT BWG THROUGH 12Z OR SO. COLD AIR ADVECTION
THROUGHOUT THE ENTIRE TROPOSPHERE CHANGES PCPN TO ALL SN AROUND 12Z.
THE SNOW WILL LAST ABOUT 5 HOURS...WITH PERHAPS A SCATTERED SNOW
SHOWER IN THE AFTN MAINLY AT LEX...BUT MVFR CIGS AND VSBYS WILL
PREVAIL BY 18Z AND H8 THERMAL TROUGH TO OUR WEST WILL KEEP LOW
CLOUDS IN AT SDF THROUGH AT LEAST THE MID AFTN...AND THEN SOME HIGH
MID DECK CLOUDS WILL BE ALL THAT IS LEFT BY 00Z THU.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...WINTER STORM WARNING UNTIL 1 PM EST /12 PM CST/ WEDNESDAY FOR
KYZ023>043-045>049-053>057.
WINTER WEATHER ADVISORY FROM 4 AM EST /3 AM CST/ TO 1 PM EST /12
PM CST/ WEDNESDAY FOR KYZ061>067-070>078-081-082.
IN...WINTER STORM WARNING UNTIL 1 PM EST /12 PM CST/ WEDNESDAY FOR
INZ076>079-083-084-089>092.
&&
$$
MESO.........JDG
SHORT TERM...AML
LONG TERM....TWF
AVIATION.....JDG/TAR
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
635 PM EST TUE JAN 27 2009
MESO AFD 1
WELL...DEEP TROPOSPHERIC MOISTURE IS ENSCONCED ACROSS THE CWA. THE
MOISTURE CHANNEL EXTENDS FROM PINEAPPLE CONNECTION FROM SW OF BAJA
CA. PWATS ARE EXTREMELY HIGH WITH 3/4 TO NEARLY 1 INCH...WHICH IS
OVER 200% OF CLIMATOLOGICAL NORMAL. THE 32 DEGREE ISOTHERM STRETCHES
FROM RUSSELLVILLE TO HODGENVILLE TO RICHMOND. THIS LINE HAS BEEN
CREEPING NORTHWARD ACROSS TIGHT BAROCLINIC ZONE TO THE NORTH. A
2050Z ACARS SOUNDING CONTINUES TO SHOW CLASSIC NASTY FZRA SOUNDING
WITH A MAX WARMTH OF +4C IN THE WARM LAYER...WHICH INCLUDES 5000 FT
OF ABOVE ZERO AIR. SFC TEMPS SHOULD WARM ANOTHER 1 TO 3 DEGREES
WITH A SW 50 KT LLVL JET.
WE HAVE BEEN RECEIVING A FEW MORE SLEET REPORTS...AND WE WILL BE
CHECKING ON THAT ANGLE. AN ACARS PLANE TAKING OFF OUT OF CVG SHOWED
A SLEET SOUNDING AT 21Z WHICH HAPPENS TO BE WHAT THEY ARE REPORTING
AT CVG. THE RUC IS SHOWING DEFINITIVE WARM NOSE OF ABV FREEZING AIR
THROUGH 06Z WITH A +2 TO + 4 AIR TEMP IN THE WARM SECTOR. WE EXPECT
ICE ACCUMULATIONS OF A TENTH OF AN INCH PER HOUR IN SOME AREAS.
PREVIOUS DISCUSSION...334 PM TUE JAN 27 2009
.SHORT TERM (TONIGHT AND TOMORROW)...
...SIGNIFICANT WINTER STORM THROUGH EARLY WEDNESDAY AFTERNOON...
ON THE NATIONAL RADAR WE HAVE WINTRY PRECIP STRETCHING FROM THE
PANHANDLE OF TEXAS TO VIRGINIA. THIS AREA OF PRECIP HAS CAUSED
NEARLY CONTINUOUS PRECIP OVER OUR FORECAST AREA (FA) TODAY.
SOUTHERN KY HAS BEEN MOSTLY RAIN THIS AFTERNOON WITH SURFACE TEMPS
HOVERING JUST ABOVE FREEZING HELPING TO IMPROVE THE ICY CONDITIONS
EXPERIENCED EARLIER. HOWEVER...CENTRAL KY...NORTHERN KY...AND
SOUTHERN INDIANA HAVE BEEN PRIMARILY FREEZING RAIN MOST OF THE
AFTERNOON WITH ICE ACCUMULATIONS AROUND A QUARTER OF AN INCH WITH
LOCALLY HIGHER AMOUNTS.
FOR THIS FORECAST PACKAGE...HAVE SIDED WITH 12Z NAM/9Z SREF BLEND
FOR QPF. RELIED ON 12Z ETA BUFKIT SOUNDINGS FOR PRECIP TYPE AND
CHANGE OVER.
TIMING...LIGHT PRECIP WILL CONTINUE WITH AN AREA OF STRONGER
PRECIP ARRIVING AS EARLY AS 3Z IN THE WESTERN FA AND EXITING THE
EASTERN FA NEAR 18Z TOMORROW. OVERNIGHT...EXPECT THE WINTRY
MIX...PRIMARILY FREEZING RAIN...TO CONTINUE OVER SOUTHERN
INDIANA...NORTHERN KY...AND CENTRAL KY THROUGH 8Z. AFTER 8Z...A
CHANGE OVER TO ALL SNOW WILL BEGIN FROM NW TO SE. OVER SOUTHERN
KY...PLAIN RAIN WILL DOMINATE MOST OF THE OVERNIGHT
HOURS...TRANSITION TO A BRIEF MIX...AND QUICKLY TO SNOW BY 12Z TO
14Z. SNOW WILL BE LIGHT TO MODERATE FROM 12Z THROUGH 18Z BEFORE
TAPER OFF OR ENDING AFTER 18Z TOMORROW.
PRECIP TYPE...EXPECT MAJOR POSSIBLY DEVASTATING ICING OVER SOUTHERN
INDIANA TONIGHT. ICE ACCUMULATIONS WILL TOP OUT AROUND 1 INCH IN
SOUTHERN INDIANA. LESSER ACCUMULATIONS WILL OCCUR OVER NORTHERN KY
AND CENTRAL KY...BUT THESE AREAS WILL STILL BE VERY HAZARDOUS.
AFTER THE PRECIP CHANGES OVER TO SNOW...THERE WILL STILL BE
SIGNIFICANT MOISTURE LEFT BEHIND FOR AS MUCH AS 5 OR 6 INCHES OF
SNOW OVER SOUTHERN INDIANA TO 1 INCH OF SNOW OVER SOUTHERN KY BY 18Z
TOMORROW. FOR MORE SPECIFIC GRAPHICAL INFORMATION...PLEASE REFER TO
OUR WEBSITE WEATHER.GOV/LMK.
AS A RESULT...WILL BE EXTENDING THE WINTER STORM WARNING THROUGH 18Z
TOMORROW AND ISSUING AN ADVY FOR SOUTHERN KY FROM 9Z TONIGHT THROUGH
18Z TOMORROW.
.LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)...
STORM SYSTEM WILL HAVE FINALLY DEPARTED BY WED EVENING...ALTHOUGH
SHALLOW BUT COLD LOW-LEVEL MOISTURE FCST TO REMAIN...SO STILL COULD
SEE SOME SNOW FLURRIES OR A FEW SNOW SHOWERS ESPECIALLY OVER NRN AND
ERN COUNTIES WED NIGHT.
ALL MODELS SHOW SOME AMPLIFICATION IN UPPER AIR PATTERN BY END OF
THE WEEK AS SHORTWAVE ENERGY DROPS SEWD INTO OH VALLEY. SOME MODEL
DIFFERENCES AS TO AMOUNT OF MOISTURE AVAILABILITY WITH THIS SYSTEM
BUT THERE IS SOME AGREEMENT THAT SOME MOISTURE BELOW 700 MB WILL BE
PRESENT ALONG WITH QUITE COLD AIR IN THE MOIST COLUMN TO GENERATE
SNOW SHOWERS ACROSS THE ENTIRE FCST AREA...WITH THE BEST CHANCES
OVER SOUTHERN IND AND N-CNTRL AND E-CNTRL KY. GIVEN THE COLD AIR
MASS... SNOW SHOWERS COULD PRODUCE A SMALL ACCUMULATION...BUT WILL
NOT BE A MAJOR SYSTEM. HIGHS ON FRI WILL PROBABLY ONLY BE IN THE
LOWER 20S NORTH TO MID TO PERHAPS UPR 20S FAR SOUTH ACROSS FCST AREA
(A LITTLE BELOW GUIDANCE).
AS UPPER TROF PULLS OFF TO THE EAST...MILDER AIR WILL ARRIVE BY
SUNDAY WITH HIGHS IN THE UPR 30S AND LOWER 40S. MODELS SHOW THE NEXT
WEATHER SYSTEM TO AFFECT OH VALLEY AROUND MONDAY TIME FRAME. GFS
AND ECMWF ARE TRYING TO SUGGEST SOME PHASING POTENTIAL WITH A SRN
STREAM SYSTEM WITH A DIGGING NRN STREAM SHORTWAVE TOWARD THE OH
VALLEY. HOWEVER...HOW TWO SHORTWAVES MAY INTERACT (IF AT ALL) AT
THIS TIME FRAME IS VERY DIFFICULT TO DIAGNOSE. RIGHT NOW...LOOKS
LIKE THIS SYSTEM COULD PRODUCE SOME RAIN SHOWERS AHEAD OF A COLD
FRONT ASSOCIATED WITH NRN STREAM SYSTEM...POSSIBLY TRANSITIONING TO
POST-FRONTAL SNOW SHOWERS. GIVEN UNCERTAINTY AT THIS TIME RANGE...
RAIN OR SNOW SHOWERS PLACED IN GRIDS SUNDAY NIGHT AND MONDAY.
&&
.AVIATION (18Z TAFS)...
IFR CONDITIONS PREVAIL AT ALL 3 SITES THRU 12Z...WITH FZRA AT LEX AND
SDF AND LIQUID RAIN AT BWG THROUGH 12Z OR SO. COLD AIR ADVECTION
THROUGHOUT THE ENTIRE TROPOSPHERE CHANGES PCPN TO ALL SN AROUND 12Z.
THE SNOW WILL LAST ABOUT 5 HOURS...WITH PERHAPS A SCATTERED SNOW
SHOWER IN THE AFTN MAINLY AT LEX...BUT MVFR CIGS AND VSBYS WILL
PREVAIL BY 18Z AND H8 THERMAL TROUGH TO OUR WEST WILL KEEP LOW
CLOUDS IN AT SDF THROUGH AT LEAST THE MID AFTN...AND THEN SOME HIGH
MID DECK CLOUDS WILL BE ALL THAT IS LEFT BY 00Z THU.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...WINTER STORM WARNING UNTIL 1 PM EST /12 PM CST/ WEDNESDAY FOR
KYZ023>043-045>049-053>057.
WINTER WEATHER ADVISORY FROM 4 AM EST /3 AM CST/ TO 1 PM EST /12
PM CST/ WEDNESDAY FOR KYZ061>067-070>078-081-082.
IN...WINTER STORM WARNING UNTIL 1 PM EST /12 PM CST/ WEDNESDAY FOR
INZ076>079-083-084-089>092.
&&
$$
MESO.........JDG
SHORT TERM...AML
LONG TERM....TWF
AVIATION.....JDG
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
550 PM EST TUE JAN 27 2009
MESO AFD 1
WELL...DEEP TROPOSPHERIC MOISTURE IS ENSCONSED ACROSS THE CWA. THE
MOISTURE CHANNEL EXTENDS FROM PINEAPPLE CONNECTION FROM SW OF BAJA
CA. PWATS ARE EXTREMEMLY HIGH WITH 3/4 TO NEARLY 1 INCH...WHICH IS
OVER 200% OF CLIMATOLOGICAL NORMAL. THE 32 DEGREE ISOTHERM STRETCHES
FROM RUSSELLVILLE TO HODGENVILLE TO RICHMOND. THIS LINE HAS BEEN
CREEPING NORTHWARD ACROSS TIGHT BAROCLINIC ZONE TO THE NORTH. A
2050Z ACARS SOUNDING CONTINUES TO SHOW CLASSIC NASTY FZRA SOUNDING
WITH A MAX WARMTH OF +4C IN THE WARM LAYER...WHICH INCLUDES 5000 FT
OF ABOVE ZERO AIR. SFC TEMPS SHOULD WARM ANOTHER 1 TO 3 DEGREES
WITH A SW 50 KT LLVL JET.
WE HAVE BEEN RECEIVING A FEW MORE SLEET REPORTS...AND WE WILL BE
CHECKING ON THAT ANGLE. AN ACARS PLANE TAKING OFF OUT OF CVG SHOWED
A SLEET SOUNDING AT 21Z WHICH HAPPENS TO BE WHAT THEY ARE REPORTING
AT CVG. THE RUC IS SHOWING DEFINITIVE WARM NOSE OF ABV FREEZING AIR
THROUGH 06Z WITH A +2 TO + 4 AIR TEMP IN THE WARM SECTOR. WE EXPECT
ICE ACCUMULATIONS OF A TENTH OF AN INCH PER HOUR IN SOME AREAS.
PREVIOUS DISCUSSION...334 PM TUE JAN 27 2009
.SHORT TERM (TONIGHT AND TOMORROW)...
...SIGNIFICANT WINTER STORM THROUGH EARLY WEDNESDAY AFTERNOON...
ON THE NATIONAL RADAR WE HAVE WINTRY PRECIP STRETCHING FROM THE
PANHANDLE OF TEXAS TO VIRGINIA. THIS AREA OF PRECIP HAS CAUSED
NEARLY CONTINUOUS PRECIP OVER OUR FORECAST AREA (FA) TODAY.
SOUTHERN KY HAS BEEN MOSTLY RAIN THIS AFTERNOON WITH SURFACE TEMPS
HOVERING JUST ABOVE FREEZING HELPING TO IMPROVE THE ICY CONDITIONS
EXPERIENCED EARLIER. HOWEVER...CENTRAL KY...NORTHERN KY...AND
SOUTHERN INDIANA HAVE BEEN PRIMARILY FREEZING RAIN MOST OF THE
AFTERNOON WITH ICE ACCUMULATIONS AROUND A QUARTER OF AN INCH WITH
LOCALLY HIGHER AMOUNTS.
FOR THIS FORECAST PACKAGE...HAVE SIDED WITH 12Z NAM/9Z SREF BLEND
FOR QPF. RELIED ON 12Z ETA BUFKIT SOUNDINGS FOR PRECIP TYPE AND
CHANGE OVER.
TIMING...LIGHT PRECIP WILL CONTINUE WITH AN AREA OF STRONGER
PRECIP ARRIVING AS EARLY AS 3Z IN THE WESTERN FA AND EXITING THE
EASTERN FA NEAR 18Z TOMORROW. OVERNIGHT...EXPECT THE WINTRY
MIX...PRIMARILY FREEZING RAIN...TO CONTINUE OVER SOUTHERN
INDIANA...NORTHERN KY...AND CENTRAL KY THROUGH 8Z. AFTER 8Z...A
CHANGE OVER TO ALL SNOW WILL BEGIN FROM NW TO SE. OVER SOUTHERN
KY...PLAIN RAIN WILL DOMINATE MOST OF THE OVERNIGHT
HOURS...TRANSITION TO A BRIEF MIX...AND QUICKLY TO SNOW BY 12Z TO
14Z. SNOW WILL BE LIGHT TO MODERATE FROM 12Z THROUGH 18Z BEFORE
TAPER OFF OR ENDING AFTER 18Z TOMORROW.
PRECIP TYPE...EXPECT MAJOR POSSIBLY DEVASTATING ICING OVER SOUTHERN
INDIANA TONIGHT. ICE ACCUMULATIONS WILL TOP OUT AROUND 1 INCH IN
SOUTHERN INDIANA. LESSER ACCUMULATIONS WILL OCCUR OVER NORTHERN KY
AND CENTRAL KY...BUT THESE AREAS WILL STILL BE VERY HAZARDOUS.
AFTER THE PRECIP CHANGES OVER TO SNOW...THERE WILL STILL BE
SIGNIFICANT MOISTURE LEFT BEHIND FOR AS MUCH AS 5 OR 6 INCHES OF
SNOW OVER SOUTHERN INDIANA TO 1 INCH OF SNOW OVER SOUTHERN KY BY 18Z
TOMORROW. FOR MORE SPECIFIC GRAPHICAL INFORMATION...PLEASE REFER TO
OUR WEBSITE WEATHER.GOV/LMK.
AS A RESULT...WILL BE EXTENDING THE WINTER STORM WARNING THROUGH 18Z
TOMORROW AND ISSUING AN ADVY FOR SOUTHERN KY FROM 9Z TONIGHT THROUGH
18Z TOMORROW.
.LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)...
STORM SYSTEM WILL HAVE FINALLY DEPARTED BY WED EVENING...ALTHOUGH
SHALLOW BUT COLD LOW-LEVEL MOISTURE FCST TO REMAIN...SO STILL COULD
SEE SOME SNOW FLURRIES OR A FEW SNOW SHOWERS ESPECIALLY OVER NRN AND
ERN COUNTIES WED NIGHT.
ALL MODELS SHOW SOME AMPLIFICATION IN UPPER AIR PATTERN BY END OF
THE WEEK AS SHORTWAVE ENERGY DROPS SEWD INTO OH VALLEY. SOME MODEL
DIFFERENCES AS TO AMOUNT OF MOISTURE AVAILABILITY WITH THIS SYSTEM
BUT THERE IS SOME AGREEMENT THAT SOME MOISTURE BELOW 700 MB WILL BE
PRESENT ALONG WITH QUITE COLD AIR IN THE MOIST COLUMN TO GENERATE
SNOW SHOWERS ACROSS THE ENTIRE FCST AREA...WITH THE BEST CHANCES
OVER SOUTHERN IND AND N-CNTRL AND E-CNTRL KY. GIVEN THE COLD AIR
MASS... SNOW SHOWERS COULD PRODUCE A SMALL ACCUMULATION...BUT WILL
NOT BE A MAJOR SYSTEM. HIGHS ON FRI WILL PROBABLY ONLY BE IN THE
LOWER 20S NORTH TO MID TO PERHAPS UPR 20S FAR SOUTH ACROSS FCST AREA
(A LITTLE BELOW GUIDANCE).
AS UPPER TROF PULLS OFF TO THE EAST...MILDER AIR WILL ARRIVE BY
SUNDAY WITH HIGHS IN THE UPR 30S AND LOWER 40S. MODELS SHOW THE NEXT
WEATHER SYSTEM TO AFFECT OH VALLEY AROUND MONDAY TIME FRAME. GFS
AND ECMWF ARE TRYING TO SUGGEST SOME PHASING POTENTIAL WITH A SRN
STREAM SYSTEM WITH A DIGGING NRN STREAM SHORTWAVE TOWARD THE OH
VALLEY. HOWEVER...HOW TWO SHORTWAVES MAY INTERACT (IF AT ALL) AT
THIS TIME FRAME IS VERY DIFFICULT TO DIAGNOSE. RIGHT NOW...LOOKS
LIKE THIS SYSTEM COULD PRODUCE SOME RAIN SHOWERS AHEAD OF A COLD
FRONT ASSOCIATED WITH NRN STREAM SYSTEM...POSSIBLY TRANSITIONING TO
POST-FRONTAL SNOW SHOWERS. GIVEN UNCERTAINTY AT THIS TIME RANGE...
RAIN OR SNOW SHOWERS PLACED IN GRIDS SUNDAY NIGHT AND MONDAY.
&&
.AVIATION (18Z TAFS)...
IFR AND LIFR CONDITIONS AT ALL THREE TAF SITES FOR THE NEXT 24
HOURS. -FZRA AT SDF COULD INCREASE IN INTENSITY OVERNIGHT...BUT
HEAVIEST ICE ACCUMULATION EXPECTED TO REMAIN NORTH OF THE OHIO
RIVER. BWG SHOULD REMAIN WARM ENOUGH THROUGH THE TIME THAT RAIN IS
FALLING TO PREVENT FREEZING. AS TEMPERATURES ALOFT COOL AROUND 12Z
PRECIP WILL CHANGE OVER TO SNOW AT ALL LOCATIONS AND TAPER OFF AT
SDF DURING THE AFTERNOON.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...WINTER STORM WARNING UNTIL 1 PM EST /12 PM CST/ WEDNESDAY FOR
KYZ023>043-045>049-053>057.
WINTER WEATHER ADVISORY FROM 4 AM EST /3 AM CST/ TO 1 PM EST /12
PM CST/ WEDNESDAY FOR KYZ061>067-070>078-081-082.
IN...WINTER STORM WARNING UNTIL 1 PM EST /12 PM CST/ WEDNESDAY FOR
INZ076>079-083-084-089>092.
&&
$$
SHORT TERM...JDG
LONG TERM....TWF
AVIATION.....AML
|