SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
825 PM PST THU FEB 19 2009
.UPDATE...CLEAR SKIES AND DRY CONDITIONS PERSIST OVER THE AREA
TONIGHT AS A RIDGE OF HIGH PRESSURE REMAINS IN PLACE. WITH THE
RIDGE AXIS TO THE EAST OF THE AREA...THE RIDGE WILL BECOME DIRTY
OVER THE NEXT COUPLE 12 TO 24 HOURS AS SOUTHWEST FLOW ALOFT
TRANSPORTS MAINLY HIGH LEVEL CLOUDINESS OVER THE AREA. LATEST GFS
300 AND 400 MB RELATIVE HUMIDITIES INDICATES THAT THE HIGH LEVEL
MOISTURE WILL SPREAD OVER THE AREA ON FRIDAY MORNING...SLIGHTLY
QUICKER THAN THE CURRENT PACKAGE INDICATES.
LATEST NAM-WRF 950 MB TEMPERATURES INITIALIZED WELL VERSUS KNKX
AND ACARS SOUNDINGS OVER THE AREA...AND SURFACE GRADIENTS
INITIALIZED ON THE WEAK SIDE OF REALITY. CURRENT PACKAGE WARMS
THE AIR MASS ON FRIDAY AND THAT SEEMS TO MAKE SENSE WITH 950 MB
BEING AROUND THE SAME WITH SLIGHT MORE OFFSHORE GRADIENTS IN
PLACE. NO UPDATE ARE PLANNED AT THIS TIME. LOCALLY BREEZY
CONDITIONS WILL CONTINUE THROUGH FRIDAY MORNING...WITH FRIDAY
LIKELY BEING EQUAL TO SLIGHTLY WARMER THAN TODAY.
A MAJORITY OF THE MODEL SOLUTIONS ARE HINTING AT PRECIPITATION
DEVELOPING OVER THE AREA ON SUNDAY. GFS SOLUTIONS ARE MORE
AGREEABLE WITH THE 12Z ECMWF. BOTH MID-RANGE MODELS INDICATE A
WEAK WARM FRONT PUSHING OVER THE AREA ON SUNDAY. 00Z NAM-WRF IS
MUCH WEAKER WITH BOUNDARY. 850 MB MIXING RATIO EXCEED 6 G/KG AT
SOME POINT ON SUNDAY OR SUNDAY EVENING AS A JET MAX NOSES INTO
SOUTHWEST CALIFORNIA. WITH A DECENT SUB-TROPICAL FETCH DEVELOPING
OVER THE EASTERN AND CENTRAL PACIFIC OCEAN IN WATER VAPOR
IMAGERY...HOPEFULLY...FUTURE MODEL SOLUTIONS MAY PROVIDE SOME
CLARITY.
&&
.PREV DISCUSSION... /ISSUED 110 PM PST THU FEB 19 2009/
LONG TERM (MON-THU)...MODELS SEEM TO BE AGREEING THAT THE FRONTAL
BOUNDARY ASSOCIATED WITH THE UPPER LOW WILL STALL SOMEWHERE ALONG
THE CENTRAL COAST OR NEAR PT CONCEPTION, DELAYING THE ARRIVAL INTO
LA/VTU COUNTIES, PERHAPS TO AS LATE AS MONDAY EVENING. EITHER WAY,
PRECIP AMOUNTS ARE EXPECTED TO BE ON THE LIGHT SIDE S OF PT
CONCEPTION. TO THE NORTH, DEPENDING ON WHERE THE FRONTAL BOUNDARY
STALLS, RAINFALL AMOUNTS COULD BE QUITE A BIT HIGHER. IT STILL
APPEARS THIS WILL BE NORTH OF OUR AREA BUT SLO AND NRN SBA COUNTY
MAY BE ON THE SRN EDGE OF THIS AXIS.
GFS SHOWS ANOTHER SYSTEM MOVING IN THU BUT THE ECMWF IS DRY. GIVEN
THE REALLY LOW CONFIDENCE WITH THE PREVIOUS SYSTEM WILL LEAVE RAIN
OUT OF THE FORECAST FOR NOW.
&&
.AVIATION...20/0115Z
VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD...EXCEPT FOR A
POSSIBILITY OF IFR TO MVFR CONDITIONS AT KPRB BETWEEN 12Z AND 16Z.
KLAX AND KBUR...VFR CONDITIONS ARE EXPECTED THROUGHOUT THE PERIOD
WITH NO WIND ISSUES.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
HALL/WOFFORD
WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
627 AM EST WED FEB 18 2009
.SYNOPSIS...
A WARM FRONT WILL MOVE NORTH THROUGH THE REGION THIS AFTERNOON.
SHOWERS AND A FEW THUNDERSTORMS ARE ALSO EXPECTED THIS AFTERNOON
INTO THIS EVENING. A COLD FRONT WILL MOVE THROUGH FROM THE WEST
TONIGHT BRINGING AN END TO THE RAIN. HIGH PRESSURE WILL MOVE OVER
THE AREA THURSDAY AND FRIDAY.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
WARM FRONT TO THE SOUTH WILL APPROACH THIS MORNING. ISENTROPIC
LIFT NORTH OF FRONT SHOULD ENHANCE PRECIPITATION LATER THIS
MORNING. LIKE GOING 100 PERCENT CHANCE. NOTICED GSP HAD SLEET
MIXED IN WITH RAIN NORTH OF CAE CWA. RAN TOP DOWN WEATHER TOOL AND
IT SHOWED CONDITIONS TOO WARM FOR ANY WINTRY MIX. SO LEFT OUT.
EVEN THOUGH WARM FRONT MOVES NORTH...NAM IS SHOWING LOW LEVEL
INVERSION PERSISTS JUST ABOUT ALL DAY. HAD CONSIDERED THE
POSSIBILITY OF H925 AND H850 WINDS MIXING DOWN IF WAA FROM SOUTH
WAS SUFFICIENT. H925 WINDS SW 45 KT. H8 WINDS INCREASE TO 65 KT
THIS AFTERNOON BUT DIRECTION BECOMES MORE WEST IMPLYING WEAKER
WAA. SO DECIDED TO KEEP WIND SPEEDS BELOW LAKE WIND ADVY CRITERIA,
ALSO...STRONG SHEAR APPROACHING FROM THE WEST REMAINS NORTH OF THE
WARM FRONT AND EXITS AREA TO NORTH BY ABOUT 18Z. EVEN THOUGH WEAK
WARM FRONT MOVES THROUGH...WILL KEEP HIGH TEMPERATURES MOSTLY IN
THE 50S. WILL HAVE SOME LOWER 60S EXTREME SOUTH PART.
WILL KEEP MENTION OF CHANCE OF THUNDERSTORMS BUT FEEL CONVECTION
WILL BE MAINLY ALOFT.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/...
BEST CHANCE OF THUNDERSTORMS IS THIS EVENING. ISOLATED SEVERE
STORMS POSSIBLE MAINLY CSRA BUT CAN`T RULE OUT ACTIVITY EXTENDING
EAST TO OGB AREA. SPC HAS SLIGHT RISK COMING UP TO THE CSRA. NAM
SHOWS LIS BECOMING MORE UNSTABLE AROUND 00Z TIME FRAME AT -1/-2.
THIS MAY ALLOW STRONGER WINDS TO DROP DOWN TO SURFACE. H925 WINDS
SW 40-45 KT AND H8 WINDS WSW 45-55 KT. THUNDERSTORMS IF ANY SHOULD
BE SHORT LIVED AS WIND SPEEDS DECREASE H925/H8 TO 40 KT BY 03Z.
COLD FRONT APPROACHING FROM WEST TONIGHT SHOULD STILL BRING ENOUGH
MOISTURE TO GO 70-80 PERCENT POPS EARLY TONIGHT. ALSO WILL HOLD
ONTO CHANCE SHOWERS AFTER MIDNIGHT UNTIL FRONT CLEARS CWA. LOW
TEMPERATURES EXPECTED TO DROP INTO THE 40S BEHIND THE FRONT.
HIGH PRESSURE WILL COVER THE REGION THURSDAY THROUGH FRIDAY.
COLDER DRIER AIR. HIGHS MAINLY MID 50S THURSDAY AND LOWER 50S
FRIDAY. LOWS THURSDAY NIGHT IN THE 20S.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AGREE WITH GFS AND ECMWF SHOWING PROGRESSIVE BUT COOL WEATHER
PATTERN DURING PERIOD. MODELS SHOW DECENT SHORT WAVE MOVING EAST
SATURDAY. INCLUDED 20-30 PERCENT CHANCE OF RAIN. TEMPERATURES
EXPECTED TO REMAIN BELOW NORMAL. HIGHS MAINLY IN THE 50S BUT
SUNDAY COOLEST DAY BEHIND STRONGEST SYSTEM WITH HIGHS MAINLY IN
THE 40S. OVERNIGHT LOWS MOSTLY IN THE 20S.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
ISENTROPIC LIFT BRINGING A BATCH OF PRECIPITATION ACROSS THE REGION
CURRENTLY. WEAK IN SITU WEDGE WILL DEVELOP THEN SLOWLY LIFT NORTH
DURING THE DAY. WILL EXPECT VSBYS/CIGS TO DROP TO MVFR LEVEL LATER
THIS MORNING. RECENT ACARS SOUNDING CONFIRMED MODEL PROJECTIONS OF
STRONG LOW LEVEL JET. WILL CARRY WS THIS MORNING. MAY SEE A BREAK
IN PRECIPITATION THIS AFTERNOON UNTIL MAIN COLD FRONT COMES
THROUGH TONIGHT. THUNDER WILL BE POSSIBLE LATE TODAY AND
TONIGHT...WITH A SEVERE POSSIBLE MAINLY ACROSS THE CSRA. FOR
NOW...WILL HANDLE WITH A TEMPO GROUP OF CB CLOUD THIS EVENING AT
AGS/DNL. THE FRONT SHOULD SWEEP THROUGH AROUND OR BY 12Z THU.
EXTENDED OUTLOOK THROUGH...BREEZY CONDITIONS POSSIBLE THURSDAY. FAIR
WEATHER EXPECTED FRIDAY. THE NEXT FRONT MAY ENTER THE REGION LATE
SATURDAY OR EARLY SUNDAY.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
559 AM CST WED FEB 18 2009
.DISCUSSION...
338 AM CST
FOG THIS MORNING...PRECIP TYPE AND AMOUNTS WITH STORM SYSTEM FOR
TODAY...AND ANOTHER STRONG CLIPPER SYSTEM FOR LATE FRIDAY WILL BE
THE MAIN FORECAST CONCERNS.
ELEVATED THUNDER HAS DEVELOPED OVERNIGHT ACROSS WEST CENTRAL
ILLINOIS...AND THESE SHOWERS CONTINUE TO TRACK ACROSS NORTHEAST
ILLINOIS EARLY THIS MORNING. STEEPEST MID LEVEL LAPSE RATES ARE IN
PLACE AT THIS TIME WITH LOCAL ACARS SOUNDINGS SUGGESTING NEAR DRY
ADIABATIC LAPSE RATES IN THE 700 HPA TO 500 HPA LAYER. THESE
SHOWERS AND PERHAPS ISOLATED THUNDERSTORM WILL RACE INTO
NORTHWEST INDIANA OVER NEXT FEW HOURS BUT AN ADDITIONAL AREA OF
PRECIPITATION CONTINUES TO DEVELOP ACROSS SOUTHEAST IOWA BEHIND
THESE ELEVATED SHOWERS. THIS DEVELOPING AREA OF PRECIPITATION
SEEMS TO BE MORE RELATED TO DEFORMATION FORCING JUST NORTH OF THE
LEAD SHORT WAVE MOVING ACROSS SOUTH CENTRAL IOWA/NORTHERN
MISSOURI. LOW/MID LEVEL FRONTOGENESIS WILL LIKELY STRENGTHEN THIS
MORNING VIA STRENGTHENING WESTERLY LOW/MID LEVEL FLOW ASSOCIATED WITH
THIS NORTHERN STREAM TROUGH DIGGING ACROSS THE NORTHERN PLAINS PER
WATER VAPOR IMAGERY THIS MORNING. PAST SEVERAL MODEL RUNS HAVE
HAD SOME INDICATION OF THIS FEATURE AND MAIN FORECAST QUESTION
WILL BE PRECIP TYPES AS IT MOVES ACROSS CWA THIS MORNING. SURFACE
LOW EVOLUTION SEEMS TO BE PANNING OUT IN A WAY FAIRLY SIMILAR TO
WHAT PAST SEVERAL NAM/WRF RUNS HAVE DEPICTED WITH MORE PRONOUNCED
PRESSURE FALLS ACROSS SOUTHERN WISCONSIN AND SECONDARY SFC LOW
DEVELOPMENT. THIS HAS RESULTED IN MORE OF AN ELONGATED SURFACE
TROUGH EXTENDING FROM MAIN SFC LOW ACROSS NORTHERN MISSOURI INTO
EAST CENTRAL WISCONSIN. COLD AIR SHOULD BE SOMEWHAT SLOW TO BE
DRAWN SOUTHWARD TODAY GIVEN THIS TYPE OF PATTERN AND RUC/NAM/GFS
THERMAL PROFILES REMAIN QUITE MARGINAL IN REGARDS TO RAIN/SNOW
PRECIP TYPE MID TO LATE MORNING. BY MID MORNING MOST OF THE COLUMN
SHOULD BE BELOW FREEZING WITH MAIN QUESTION AS TO TRENDS WITH TEMPS/WET
BULBS IN VERY LOWEST LEVELS. EXPECTING MOST OF THE PRECIPITATION
THIS MORNING WILL BE LIQUID BUT COULD HAVE A BRIEF PERIOD OF
DECENT WET SNOWFALL RATES ASSOCIATED WITH THE FRONTOGENESIS
FORCING BEFORE TAPERING OFF. IF THE PRECIP DOES CHANGE OVER TO SNOW
BEFORE TAPERING OFF TOWARD MIDDAY...WARMISH LOW LEVELS WILL LIKELY
MAKE ANY APPRECIABLE SNOW ACCUMULATION HARD TO COME BY. HAVE
DECREASED SNOW ACCUMULATIONS TODAY AND TRIED TO SHOW A RELATIVELY
NARROW CORRIDOR WHERE SOME MINOR ACCUMS OF AN INCH OR LESS WOULD
BE POSSIBLE ALONG OR JUST NORTH OF INTERSTATE 80 CORRIDOR WHERE
THIS FRONTOGENESIS FORCING IS FORECAST BE MOST PRONOUNCED. THE
AFOREMENTIONED SFC TROUGH EXTENDING INTO NORTH CENTRAL ILLINOIS
HAS LED TO A WEAK SFC PRESSURE GRADIENT. THE WEAK GRADIENT COMBINED
WITH LOW LEVEL MOISTURE HAVING ADVECTED INTO THE AREA HAS RESULTED
IN SOME FOG...LOCALLY DENSE. WILL BE ISSUING A DENSE FOG ADVISORY
THROUGH MID MORNING MAINLY FOR NORTHERN HALF OF THE FORECAST
AREA...NORTH OF THE SFC LOW TRACK. THE THREAT OF ANY THUNDER
SHOULD WANE BY MID MORNING AS STEEPER MID LEVEL LAPSE RATES SHIFT
EAST OF THE AREA.
STRONGER DPVA WITH THE NORTHERN STREAM SHORT WAVE WILL NOT LIKELY
IMPACT NORTHEAST ILLINOIS/NORTHWEST INDIANA UNTIL THIS EVENING SO
EXPECTING A LULL IN PRECIP THIS AFTERNOON. DID KEEP SOME LIKELY POPS
GOING FOR SNOW SHOWERS ACROSS NORTHEAST ILLINOIS INTO NORTHWEST
INDIANA BUT ACCUMULATIONS SHOULD MINOR...GENERALLY LESS THAN A HALF
INCH. POSSIBLE EXCEPTION TO THIS IS FOR PORTIONS OF NORTHWEST
INDIANA WHERE STRONGEST DPVA IS EXPECTED TO OCCUR ON TOP OF LAKE
EFFECT SNOW POTENTIAL. LAKE INDUCED EQUIL. LEVELS INCREASE TO AROUND
9K FT TONIGHT AS COLDER AIR DROPS SOUTHWARD INTO THE AREA. IT STILL
APPEARS AS THOUGH A NORTHWEST LOW LEVEL FLOW COMPONENT SHOULD FAVOR
HEAVIER LAKE EFFECT ACCUMULATIONS EAST OF PORTER COUNTY. COMBINATION
OF LAKE EFFECT AND SYNOPTIC FORCING MAY PRODUCE A FEW INCHES OF SNOW
ACCUMULATION THIS EVENING HOWEVER. WINDS WILL STRENGTHEN AS COLD
ADVECTION INTENSIFIES THIS EVENING WITH SOME GUSTS TO 35 MPH
POSSIBLE BY THIS EVENING AND WILL CONTINUE THROUGH THE NIGHT.
MUCH COLDER TEMPERATURES IN STORE FOR THURSDAY WITH MODELS
CONTINUING TO BRING DOWN 850 HPA TEMPS OF -18 TO -20 DEG CELS. GOING
HIGHS FROM AROUND 20 FAR NORTH TO MID 20S SOUTH STILL APPEARS TO BE
IN THE BALLPARK. A FEW LINGERING LAKE EFFECT SNOW SHOWERS MAY AFFECT
PORTER COUNTY INTO THURSDAY. COLDEST NIGHT OF THE PERIOD WILL LIKELY
BE ON THURSDAY NIGHT WITH LESS CLOUD COVER AND WINDS BEGINNING TO
SLACKEN OFF A BIT.
ATTENTION THEN TURNS TO NEXT CLIPPER SYSTEM TO AFFECT THE AREA
FRIDAY NIGHT INTO EARLY SATURDAY. OVERALL THERE HAS BEEN SOME
DECENT RUN TO RUN CONSISTENCY WITH THIS FEATURE...JUST SOME EXPECTED
DIFFERENCES IN THE STRENGTH OF THE UPPER LEVEL WAVE. HAVE TRENDED
TOWARD SREF/GFS IDEA OF SFC LOW TRACKING THROUGH CENTRAL ILLINOIS
FRIDAY EVENING. SOME IMPRESSIVE ISENTROPIC ASCENT WOULD ALSO
ACCOMPANY THIS WAVE ASSUMING THIS SOLUTION VERIFIES WHICH COULD
SPREAD ADVISORY LEVEL SNOW ACCUMULATIONS ACROSS THE AREA FRIDAY
NIGHT. DID INCREASE POPS FOR FRIDAY NIGHT...AND IF THIS SOLUTION
REMAINS CONSISTENT WILL LIKELY NEED TO BEEF UP THIS MENTION IN
NEXT FEW FORECASTS. REINFORCING COLD AIR WILL MOVE IN BEHIND THIS
SYSTEM FOR THE WEEKEND...FOLLOWED BY DRY CONDITIONS AND MODERATING
TEMPS FOR MONDAY AS UPPER FLOW DEAMPLIFIES.
MARSILI
&&
.AVIATION...
1200 UTC TAFS...TAF CONCERNS ARE MANY THIS MORNING..WITH TRENDS
WITH RESPECT TO VLIFR/LIFR/IFR CEILINGS/VSBYS AND PRECIP TYPE MAIN
FOCI OF FORECAST.
11Z/5 AM CST SURFACE ANALYSIS DEPICTS SURFACE LOW PRESSURE OVER
WESTERN IL VICINITY KMQB. INVERTED TROUGH EXTENDS NORTHEAST THROUGH
KRFD INTO WI...WHILE PSEUDO WARMFRONT EXTENDS NORTHEAST/EAST TOWARD
CHICAGO. WEAKENING OF PRESSURE GRADIENT AND RESULTING LIGHT SURFACE
WINDS IN PROXIMITY TO TROUGH ACROSS NORTHERN ILLINOIS HAS ALLOWED
VLIFR CONDITIONS TO DEVELOP OVERNIGHT IN SATURATED LOW LEVEL
AIRMASS. VISIBILITIES OF 1/8 TO 1/2 MILE HAVE BEEN COMMON WITH
CEILINGS 100-200 FEET NORTH OF PSEUDO WARM FRONTAL FEATURE...WHILE
REMAINING LIFR SOUTH OF THIS FEATURE WITH VSBYS STILL A COUPLE OF
MILES OR BETTER. IN ADDITION...A PAIR OF MID LEVEL SHORT WAVES HAVE
BROUGHT RAIN ACROSS THE AREA ALONG AND SOUTH OF THE INTERSTATE 88
CORRIDOR FROM ROUGHLY KSQI TO KORD...AND THIS IS HELPING TO IMPROVE
VISIBILITY IN AREAS WHERE HEAVIER RAIN FALLS.
SECOND MID LEVEL WAVE IS NOW ENTERING WESTERN IL...AND WILL
TRANSITION FORECAST AREA THROUGH MID MORNING. 06Z NAM TAKES THIS
FEATURE AND ASSOCIATED SURFACE LOW/TROUGH TO THE IL/IN STATE LINE BY
AROUND 1530Z...WITH SOME IMPROVEMENT ABOVE VLIFR EXPECTED EARLY DUE
TO INCREASE IN RAIN ACROSS THE AREA. AREA OF ELEVATED THUNDERSTORMS
NEAR KFSW EXPECTED TO REMAIN OFF TO THE SOUTH OF THE TERMINALS AS
WAVE MOVES EAST THIS MORNING. RAIN WILL SHIFT EAST OF THE AREA BY
MID MORNING AS WAVE DEPARTS...THOUGH SECOND AREA OF LIGHT
PRECIPITATION ASSOCIATED WITH WEAK DEFORMATION BAND NOW MOVING INTO
NORTHWEST IL WILL PUSH ACROSS THE AREA THROUGH LATE MORNING. LOW
LEVEL WIND SHIFT TO NORTHWEST BEHIND SURFACE TROUGH WILL RESULT IN
COOLING OF COLUMN AND CHANGEOVER OF LIGHT RAIN TO LIGHT RAIN/SNOW
MIX OR SNOW. PRECIP SHOULD END BY LATE MORNING FROM WEST TO EAST AS
THIS DEFORMATION BAND MOVES EAST. INCREASING NORTHWEST LOW LEVEL
WIND FIELD SHOULD HELP MAINTAIN SLOW IMPROVEMENT IN VISIBILITY
THROUGH THE MORNING/EARLY AFTERNOON...THOUGH FORECAST SOUNDINGS AND
CURRENT UPSTREAM CONDITIONS INDICATE TERMINALS WILL REMAIN IFR
THROUGH THE DAY.
ANOTHER MID LEVEL TROUGH DROPS SOUTHEAST ACROSS THE FORECAST AREA
LATE THIS AFTERNOON/EVENING PRESENTING THE POTENTIAL FOR A PERIOD OF
SNOW SHOWERS. 06Z NAM MAINTAINS TREND OF CENTERING THIS PERIOD OF
SNOW A COUPLE OF HOURS AROUND 00Z/6 PM CST...BEFORE SHIFTING EAST OF
THE FORECAST AREA MID/LATE EVENING. WHILE A FEW FLURRIES MAY LINGER
FROM MVFR STRATOCU DECK INTO THE OVERNIGHT HOURS...REMAINDER OF
FORECAST SHOULD ENJOY A GRADUAL LIFTING OF MVFR CEILINGS.
RATZER
&&
.MARINE...
313 AM CST
LOW PRESSURE OVER FAR NORTHEAST MISSOURI THIS MORNING WILL
CONTINUE TO TRACK EAST/NORTHEAST ACROSS NORTHERN ILLINOIS THIS
MORNING...WHILE WEAKER TROUGH EXTENDING NORTH INTO WISCONSIN
PASSES ACROSS LAKE MICHIGAN. WINDS HAVE DECREASED AS GRADIENT
BECOMES WEAKER IN VICINITY OF THIS TROUGH EARLY THIS MORNING...
BUT WILL STRENGTHEN AGAIN LATER THIS MORNING FROM THE NORTH AS THE
TROUGH/LOW MOVE EAST OF THE LAKE AND CONTINUE TO DEEPEN.
STRENGTHENING LOW AND STRONG LOW LEVEL COLD ADVECTION TO FOLLOW STILL
APPEAR TO SUPPORT ABOUT A 30 HOUR PERIOD OF 35-40 KNOT NORTH TO
NORTHWEST GALES ACROSS THE LAKE BEGINNING ON THE NORTH END EARLY
THIS AFTERNOON...AND SPREADING SOUTH ACROSS THE REMAINDER OF THE
LAKE BY EARLY THIS EVENING. FAR SOUTH/SOUTHWEST PARTS OF THE LAKE
WILL LIKELY BE LAST TO SEE WINDS INCREASE TO GALE FORCE...LATE
AFTERNOON OR TOWARD THIS EVENING...THOUGH AM HESITANT TO CHANGE
EXISTING GALE WARNING START TIME AS WILL BE A GRADUAL INCREASE
FROM THE NORTH THROUGH THE AFTERNOON. TIMING OF HEAVY FREEZING
SPRAY HEADLINES LOOKS GOOD. WINDS SHOULD GRADUALLY DECREASE
OVERNIGHT THURSDAY NIGHT AS HIGH PRESSURE RIDGE BUILDS SOUTH
ACROSS PLAINS.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ014 UNTIL 10 AM WEDNESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878...NOON WEDNESDAY TO MIDNIGHT FRIDAY.
HEAVY FREEZING SPRAY WARNING...LMZ080-LMZ261-LMZ362-LMZ364-
LMZ366-LMZ563-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-
LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...6 PM WEDNESDAY
TO 6 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
339 AM CST WED FEB 18 2009
.DISCUSSION...
338 AM CST
FOG THIS MORNING...PRECIP TYPE AND AMOUNTS WITH STORM SYSTEM FOR
TODAY...AND ANOTHER STRONG CLIPPER SYSTEM FOR LATE FRIDAY WILL BE
THE MAIN FORECAST CONCERNS.
ELEVATED THUNDER HAS DEVELOPED OVERNIGHT ACROSS WEST CENTRAL
ILLINOIS...AND THESE SHOWERS CONTINUE TO TRACK ACROSS NORTHEAST
ILLINOIS EARLY THIS MORNING. STEEPEST MID LEVEL LAPSE RATES ARE IN
PLACE AT THIS TIME WITH LOCAL ACARS SOUNDINGS SUGGESTING NEAR DRY
ADIABATIC LAPSE RATES IN THE 700 HPA TO 500 HPA LAYER. THESE
SHOWERS AND PERHAPS ISOLATED THUNDERSTORM WILL RACE INTO
NORTHWEST INDIANA OVER NEXT FEW HOURS BUT AN ADDITIONAL AREA OF
PRECIPITATION CONTINUES TO DEVELOP ACROSS SOUTHEAST IOWA BEHIND
THESE ELEVATED SHOWERS. THIS DEVELOPING AREA OF PRECIPITATION
SEEMS TO BE MORE RELATED TO DEFORMATION FORCING JUST NORTH OF THE
LEAD SHORT WAVE MOVING ACROSS SOUTH CENTRAL IOWA/NORTHERN
MISSOURI. LOW/MID LEVEL FRONTOGENESIS WILL LIKELY STRENGTHEN THIS
MORNING VIA STRENGTHENING WESTERLY LOW/MID LEVEL FLOW ASSOCIATED WITH
THIS NORTHERN STREAM TROUGH DIGGING ACROSS THE NORTHERN PLAINS PER
WATER VAPOR IMAGERY THIS MORNING. PAST SEVERAL MODEL RUNS HAVE
HAD SOME INDICATION OF THIS FEATURE AND MAIN FORECAST QUESTION
WILL BE PRECIP TYPES AS IT MOVES ACROSS CWA THIS MORNING. SURFACE
LOW EVOLUTION SEEMS TO BE PANNING OUT IN A WAY FAIRLY SIMILAR TO
WHAT PAST SEVERAL NAM/WRF RUNS HAVE DEPICTED WITH MORE PRONOUNCED
PRESSURE FALLS ACROSS SOUTHERN WISCONSIN AND SECONDARY SFC LOW
DEVELOPMENT. THIS HAS RESULTED IN MORE OF AN ELONGATED SURFACE
TROUGH EXTENDING FROM MAIN SFC LOW ACROSS NORTHERN MISSOURI INTO
EAST CENTRAL WISCONSIN. COLD AIR SHOULD BE SOMEWHAT SLOW TO BE
DRAWN SOUTHWARD TODAY GIVEN THIS TYPE OF PATTERN AND RUC/NAM/GFS
THERMAL PROFILES REMAIN QUITE MARGINAL IN REGARDS TO RAIN/SNOW
PRECIP TYPE MID TO LATE MORNING. BY MID MORNING MOST OF THE COLUMN
SHOULD BE BELOW FREEZING WITH MAIN QUESTION AS TO TRENDS WITH TEMPS/WET
BULBS IN VERY LOWEST LEVELS. EXPECTING MOST OF THE PRECIPITATION
THIS MORNING WILL BE LIQUID BUT COULD HAVE A BRIEF PERIOD OF
DECENT WET SNOWFALL RATES ASSOCIATED WITH THE FRONTOGENESIS
FORCING BEFORE TAPERING OFF. IF THE PRECIP DOES CHANGE OVER TO SNOW
BEFORE TAPERING OFF TOWARD MIDDAY...WARMISH LOW LEVELS WILL LIKELY
MAKE ANY APPRECIABLE SNOW ACCUMULATION HARD TO COME BY. HAVE
DECREASED SNOW ACCUMULATIONS TODAY AND TRIED TO SHOW A RELATIVELY
NARROW CORRIDOR WHERE SOME MINOR ACCUMS OF AN INCH OR LESS WOULD
BE POSSIBLE ALONG OR JUST NORTH OF INTERSTATE 80 CORRIDOR WHERE
THIS FRONTOGENESIS FORCING IS FORECAST BE MOST PRONOUNCED. THE
AFOREMENTIONED SFC TROUGH EXTENDING INTO NORTH CENTRAL ILLINOIS
HAS LED TO A WEAK SFC PRESSURE GRADIENT. THE WEAK GRADIENT COMBINED
WITH LOW LEVEL MOISTURE HAVING ADVECTED INTO THE AREA HAS RESULTED
IN SOME FOG...LOCALLY DENSE. WILL BE ISSUING A DENSE FOG ADVISORY
THROUGH MID MORNING MAINLY FOR NORTHERN HALF OF THE FORECAST
AREA...NORTH OF THE SFC LOW TRACK. THE THREAT OF ANY THUNDER
SHOULD WANE BY MID MORNING AS STEEPER MID LEVEL LAPSE RATES SHIFT
EAST OF THE AREA.
STRONGER DPVA WITH THE NORTHERN STREAM SHORT WAVE WILL NOT LIKELY
IMPACT NORTHEAST ILLINOIS/NORTHWEST INDIANA UNTIL THIS EVENING SO
EXPECTING A LULL IN PRECIP THIS AFTERNOON. DID KEEP SOME LIKELY POPS
GOING FOR SNOW SHOWERS ACROSS NORTHEAST ILLINOIS INTO NORTHWEST
INDIANA BUT ACCUMULATIONS SHOULD MINOR...GENERALLY LESS THAN A HALF
INCH. POSSIBLE EXCEPTION TO THIS IS FOR PORTIONS OF NORTHWEST
INDIANA WHERE STRONGEST DPVA IS EXPECTED TO OCCUR ON TOP OF LAKE
EFFECT SNOW POTENTIAL. LAKE INDUCED EQUIL. LEVELS INCREASE TO AROUND
9K FT TONIGHT AS COLDER AIR DROPS SOUTHWARD INTO THE AREA. IT STILL
APPEARS AS THOUGH A NORTHWEST LOW LEVEL FLOW COMPONENT SHOULD FAVOR
HEAVIER LAKE EFFECT ACCUMULATIONS EAST OF PORTER COUNTY. COMBINATION
OF LAKE EFFECT AND SYNOPTIC FORCING MAY PRODUCE A FEW INCHES OF SNOW
ACCUMULATION THIS EVENING HOWEVER. WINDS WILL STRENGTHEN AS COLD
ADVECTION INTENSIFIES THIS EVENING WITH SOME GUSTS TO 35 MPH
POSSIBLE BY THIS EVENING AND WILL CONTINUE THROUGH THE NIGHT.
MUCH COLDER TEMPERATURES IN STORE FOR THURSDAY WITH MODELS
CONTINUING TO BRING DOWN 850 HPA TEMPS OF -18 TO -20 DEG CELS. GOING
HIGHS FROM AROUND 20 FAR NORTH TO MID 20S SOUTH STILL APPEARS TO BE
IN THE BALLPARK. A FEW LINGERING LAKE EFFECT SNOW SHOWERS MAY AFFECT
PORTER COUNTY INTO THURSDAY. COLDEST NIGHT OF THE PERIOD WILL LIKELY
BE ON THURSDAY NIGHT WITH LESS CLOUD COVER AND WINDS BEGINNING TO
SLACKEN OFF A BIT.
ATTENTION THEN TURNS TO NEXT CLIPPER SYSTEM TO AFFECT THE AREA
FRIDAY NIGHT INTO EARLY SATURDAY. OVERALL THERE HAS BEEN SOME
DECENT RUN TO RUN CONSISTENCY WITH THIS FEATURE...JUST SOME EXPECTED
DIFFERENCES IN THE STRENGTH OF THE UPPER LEVEL WAVE. HAVE TRENDED
TOWARD SREF/GFS IDEA OF SFC LOW TRACKING THROUGH CENTRAL ILLINOIS
FRIDAY EVENING. SOME IMPRESSIVE ISENTROPIC ASCENT WOULD ALSO
ACCOMPANY THIS WAVE ASSUMING THIS SOLUTION VERIFIES WHICH COULD
SPREAD ADVISORY LEVEL SNOW ACCUMULATIONS ACROSS THE AREA FRIDAY
NIGHT. DID INCREASE POPS FOR FRIDAY NIGHT...AND IF THIS SOLUTION
REMAINS CONSISTENT WILL LIKELY NEED TO BEEF UP THIS MENTION IN
NEXT FEW FORECASTS. REINFORCING COLD AIR WILL MOVE IN BEHIND THIS
SYSTEM FOR THE WEEKEND...FOLLOWED BY DRY CONDITIONS AND MODERATING
TEMPS FOR MONDAY AS UPPER FLOW DEAMPLIFIES.
MARSILI
&&
.AVIATION...
1053 PM CST
0600 UTC TAFS...WIDESPREAD IFR CONDITIONS WITH DZ AND LIGHT FOG
DEVELOPED TUESDAY EVENING AND WILL LIKELY PERSIST INTO THE FIRST
SEVERAL HOURS OF THIS TAF CYCLE. INCREASING VERTICAL ASCENT IN
LEFT EXIT REGION OF APPROACHING JET (100KT+ 400MB PER PROFILERS)
COMBINED WITH CONTINUED ISENTROPIC ASCENT COULD BE ENOUGH TO
ALLOW ELEVATED PARCELS TO REACH THEIR LFC LATE TONIGHT WITH
SCATTERED SHRA POSSIBLY EVEN SOME ISOLD TS TO DEVELOP. THIS
ACTIVITY SHOULD QUICKLY MOVE EAST OF THE TERMINALS SHORTLY AFTER
SUNRISE WITH A BIT OF A LULL BEFORE SOME DEFORMATION RAIN/WET
SNOWS OCCUR LATER IN THE MORNING. GENERALLY GIVEN THE
OPEN WAVE/POSITIVELY TILTED NATURE OF THE SYSTEM AND WITH SFC LOW
TRACKING SO FAR NORTH FEEL PROSPECTS FOR ANY EXTENDED PERIOD OF
APPRECIABLE SNOW WILL BE LOW...HOWEVER A QUICK BURST OF IFR OR
LOWER VSBYS WITH WET SNOW COULD OCCUR BEFORE PRECIP BECOMES MORE
SNOW SHOWERY/SNOW FLURRY IN NATURE IN THE AFTERNOON. SOME SNOW
SHOWERS/FLURRIES COULD CONTINUE INTO THE EVENING TOMORROW IN
STRONG COLD AIR ADVECTION REGIME AND WITH NORTHERN STREAM
SHORTWAVE ROTATING SOUTHWARD. WHILE -SHSN MAY LINGER INTO THE
AFTERNOON...SHOULD SEE CIGS CLIMB TO MVFR RANGE AS DEPTH OF COLD
AIR INCREASES. WINDS SHOULD SHIFT TO NORTHWEST WEDNESDAY MORNING
AND REALLY BEGIN TO RAMP UP DURING THE AFTERNOON WITH GUSTS TO
AROUND 30KT LIKELY DURING THE LATE AFTERNOON AND EVENING.
IZZI
&&
.MARINE...
313 AM CST
LOW PRESSURE OVER FAR NORTHEAST MISSOURI THIS MORNING WILL
CONTINUE TO TRACK EAST/NORTHEAST ACROSS NORTHERN ILLINOIS THIS
MORNING...WHILE WEAKER TROUGH EXTENDING NORTH INTO WISCONSIN
PASSES ACROSS LAKE MICHIGAN. WINDS HAVE DECREASED AS GRADIENT
BECOMES WEAKER IN VICINITY OF THIS TROUGH EARLY THIS MORNING...
BUT WILL STRENGTHEN AGAIN LATER THIS MORNING FROM THE NORTH AS THE
TROUGH/LOW MOVE EAST OF THE LAKE AND CONTINUE TO DEEPEN.
STRENGTHENING LOW AND STRONG LOW LEVEL COLD ADVECTION TO FOLLOW STILL
APPEAR TO SUPPORT ABOUT A 30 HOUR PERIOD OF 35-40 KNOT NORTH TO
NORTHWEST GALES ACROSS THE LAKE BEGINNING ON THE NORTH END EARLY
THIS AFTERNOON...AND SPREADING SOUTH ACROSS THE REMAINDER OF THE
LAKE BY EARLY THIS EVENING. FAR SOUTH/SOUTHWEST PARTS OF THE LAKE
WILL LIKELY BE LAST TO SEE WINDS INCREASE TO GALE FORCE...LATE
AFTERNOON OR TOWARD THIS EVENING...THOUGH AM HESITANT TO CHANGE
EXISTING GALE WARNING START TIME AS WILL BE A GRADUAL INCREASE
FROM THE NORTH THROUGH THE AFTERNOON. TIMING OF HEAVY FREEZING
SPRAY HEADLINES LOOKS GOOD. WINDS SHOULD GRADUALLY DECREASE
OVERNIGHT THURSDAY NIGHT AS HIGH PRESSURE RIDGE BUILDS SOUTH
ACROSS PLAINS.
RATZER
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...DENSE FOG ADVISORY...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-
ILZ011-ILZ012-ILZ013-ILZ014 UNTIL 10 AM WEDNESDAY.
IN...NONE.
LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ740-LMZ741-LMZ742-
LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-
LMZ874-LMZ876-LMZ878...NOON WEDNESDAY TO MIDNIGHT FRIDAY.
HEAVY FREEZING SPRAY WARNING...LMZ080-LMZ261-LMZ362-LMZ364-
LMZ366-LMZ563-LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-
LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-LMZ779-
LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...6 PM WEDNESDAY
TO 6 PM THURSDAY.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
915 AM EST WED FEB 18 2009
.UPDATE...
MADE A FEW TWEAKS TO THE FORECAST. RATHER SOLID AREA OF LIGHT RAIN
FORMED EARLIER OVER SOUTHERN INDIANA AND CONTINUES TO SLIDE TO THE
ESE ACROSS SOUTHERN INDIANA AND INTO NORTHERN CENTRAL KENTUCKY.
UPPED MORNING POPS TO CATEGORICAL IN THE AREAS THAT ARE TO BE
AFFECTED BY THIS AREA OF RAIN.
ALSO...REDUCED MORNING POPS IN THE SOUTH WHERE THE RAIN WILL MISS
AND PROSPECTS FOR DEVELOPMENT THIS MORNING ARE SLIMMER. KEPT POPS IN
THE CHANCE CATEGORY IN THE SOUTH.
NO OTHER SIGNIFICANT CHANGES AT THIS TIME.
&&
.SHORT TERM (TODAY AND TONIGHT)...
MASS OF WARM-AIR ADVECTION SHOWERS AND STORMS ARE AFFECTING MUCH OF
THE SOUTHERN CWA. A FEW STRONG STORMS HAVE FORMED WITHIN THE
MASS...PRODUCING PEA SIZE HAIL NEAR BOWLING GREEN. ONE STORM THAT
PRODUCED NICKEL HAIL NEAR THE KY/TN BORDER MOVED ACROSS LOGAN AND
SIMPSON BUT HAS SINCE WANED. EVERYTHING NOW IS BEHAVING...WITH HEAVY
RAINFALL TRAINING OVER THE SAME AREAS...AND LOTS OF LIGHTNING. GUSTY
WINDS ARE ALSO OCCURRING...WITH PEAKS AROUND 40-45 MPH. BUT RECENT
ACARS SOUNDINGS SHOW NICE CAPPING AT 800MB...SO ANY SEVERE WIND
GUSTS MIXING DOWN SHOULD NOT OCCUR. THROUGH SUNRISE...ANY STRONG
STORM WILL BE CAPABLE OF PRODUCING PEA AND MARBLE SIZE HAIL.
THIS AREA OF SHOWERS AND STORMS IS ALL AHEAD OF AN APPROACHING LOW
PRESSURE CENTER OVER NW MISSOURI. THIS LOW WILL PUSH TOWARDS NE
INDIANA TODAY...WHICH WILL ALSO PUSH THESE SHOWERS AND STORMS EAST
OF THE CWA MOSTLY BY 18Z. THEN THE COLD FRONT FROM THE LOW WILL PASS
THROUGH THE CWA BETWEEN ROUGHLY 21Z AND 03Z. THE NMM-WRF HAS A GOOD
HANDLE ON CURRENT PRECIP...AND THAT MODEL SHOWS MORE SHOWERS/STORMS
DEVELOPING OVER OUR ERN CWA ALONG THE COLD FRONT. ASSUMING THE CAP
ALOFT CAN BREAK THIS AFTERNOON...WILL GO WITH THIS MODEL SOLUTION
AND HAVE THE HIGHEST POPS OVER THE ERN HALF OF THE CWA. DESPITE
CLOUDS AND PRECIP...TEMPS SHOULD CLIMB ESPECIALLY THIS AFTERNOON
INTO THE MID 50S N TO THE MID 60S S. WINDS WILL CONTINUE TO BE
GUSTY...ESPECIALLY LATER THIS AFTERNOON AHEAD OF THE COLD
FRONT...WITH GUSTS UP TO 35 MPH BEING POSSIBLE.
TONIGHT...ON THE BACK SIDE OF THE LOW/FRONT...TEMPS SHOULD FALL INTO
THE UPPER 20S AND LOW 30S. RESIDUAL WRAP-AROUND MOISTURE WILL AFFECT
MAINLY OUR NERN CWA OVERNIGHT...WHERE RAIN WILL CHANGE TO SNOW
SHOWERS. THIS WILL MOST LIKELY OCCUR OVER THE NORTHERN BLUEGRASS
AFTER MIDNIGHT TOWARDS DAWN THURSDAY.
.LONG TERM (THURSDAY THROUGH TUESDAY)...
NOT TOO MANY CHANGES REQUIRED THROUGH THE EXTENDED THIS MORNING.
MAIN CHALLENGES WILL BE MOVING OUT PRECIPITATION ON THURSDAY AND
ANOTHER CLIPPER SYSTEM BRINGING A CHANCE FOR LIGHT ACCUMULATING SNOW
ON SATURDAY. A WEAK DISTURBANCE ON TUESDAY NEAR THE END OF THE
FORECAST PERIOD COULD ALSO BRING ANOTHER ROUND OF PRECIPITATION.
THURSDAY THROUGH SATURDAY...
UPPER LEVEL LOW OVER MICHIGAN WILL MOVE EASTWARD INTO UPSTATE NEW
YORK PULLING SURFACE LOW INTO THE NORTHEAST U.S. NORTHWEST FLOW
ACROSS THE AREA WILL USHER IN HIGH SURFACE PRESSURE AND LINGERING
PRECIPITATION SHOULD MOVE EAST OF THE AREA BY MIDDAY WITH SOME
FLURRIES POSSIBLE ACROSS NORTH CENTRAL KY AND THE BLUEGRASS REGION
IN THE AFTERNOON BEFORE DRIER CONDITIONS SET IN THURSDAY NIGHT AND
FRIDAY. WITH HIGHS ONLY TOPPING OUT IN THE LOW 30S ON THURSDAY AND
CLEARING SKIES OVERNIGHT TEMPS WILL BOTTOM OUT IN THE TEENS BY
FRIDAY MORNING. PLENTY OF SUNSHINE ON FRIDAY AND SOME LOW LEVEL WAA
WILL ALLOW TEMPS TO REBOUND INTO THE MID 40S IN THE SOUTHWEST TO THE
UPPER 30S IN THE NORTHEAST. CLOUDS WILL INCREASE DURING THE LATE
AFTERNOON AND EARLY EVENING ON FRIDAY AS THE NEXT CLIPPER SYSTEM
APPROACHES THE AREA LATE FRIDAY NIGHT AND SATURDAY. EXPECT A MIX OF
RAIN/SNOW LATE FRIDAY EVENING MAINLY ACROSS AREAS WEST OF INTERSTATE
65 WITH PRECIPITATION SPREADING EASTWARD TOWARD SATURDAY MORNING AND
CHANGING TO ALL SNOW AFTER MIDNIGHT. EXPECT ACCUMULATION FRIDAY
NIGHT TO BE AROUND A HALF INCH IN ALL BUT THE FAR SOUTHWEST PORTIONS
OF THE FORECAST AREA WHERE LITTLE TO NO ACCUMULATION IS EXPECTED.
SNOW SHOWERS WILL CONTINUE THROUGH MIDDAY ON SATURDAY WHEN A COLD
FRONT PUSHES THROUGH AND A DRY SLOT MOVES ACROSS THE FORECAST AREA.
ADDITIONAL ACCUMULATIONS OF LESS THAN A HALF INCH ARE EXPECTED AT
THIS TIME ACROSS THE BLUEGRASS REGION OF KY. AS UPPER LOW AND
SURFACE LOW MOVE ACROSS NORTH OH AND UP THE EASTERN GREAT
LAKES...WRAP AROUND MOISTURE COUPLED WITH NORTHERLY FLOW WILL BRING
A CHANCE OF LIGHT SNOW SHOWERS TO AREAS MAINLY EAST OF INTERSTATE 75
ON SATURDAY NIGHT...LITTLE TO NO ADDITIONAL ACCUMULATIONS ARE
EXPECTED. TEMPERATURES ON SATURDAY MORNING WILL START OUT IN THE
UPPER 20S AND CLIMB TO THE MID 30S.
SUNDAY THROUGH TUESDAY...
TROUGH AXIS SWINGS THROUGH AND SHIFTS EAST OF THE AREA BY SUNDAY
MORNING AND CLEARING SKIES ARE EXPECTED. EXPECT TEMPERATURES TO BE A
FEW DEGREES COLDER DESPITE LESS CLOUD COVER AS DEEP TROUGH TO THE
EAST AND NORTHERLY FLOW OVER THE REGION ALLOWS COLDER AIR TO SEEP
SOUTHWARD. EXPECT HIGHS IN THE LOW TO MID 30S ON SUNDAY.
SURFACE HIGH PRESSURE BUILDS OVER THE SOUTHEAST STATES ON MONDAY
WITH ZONAL FLOW ALOFT ALLOWING WAA TO SET UP WITH SOUTHERLY SURFACE
FLOW. MOSTLY SUNNY SKIES WILL GIVE WAY TO INCREASING CLOUDINESS BY
LATE MONDAY AFTERNOON AS ANOTHER WEAK CLIPPER SYSTEM APPROACHES THE
AREA FOR TUESDAY. PLENTY OF MOISTURE WILL BEGIN STREAMING INTO THE
AREA FROM THE WESTERN GULF COAST OVERNIGHT MONDAY AND SHOWERS WILL
BE POSSIBLE BY TUESDAY MIDDAY AS ANOTHER COOL FRONT MAKES ITS WAY
THROUGH THE REGION. EXPECT HIGHS ON MONDAY AND TUESDAY IN THE 40S
WITH OVERNIGHT LOWS IN THE UPPER 20S TO LOW 30S.
&&
.AVIATION (12Z TAFS)...
SHOWERS/ISOLATED THUNDERSTORMS WILL CONTINUE TO AFFECT LEX AND MAYBE
BWG THROUGH 13-14Z THIS MORNING BEFORE ALL RAIN MOVES OFF TO THE
EAST. MVFR-IFR CIGS WILL CONTINUE THROUGH ABOUT 18Z FOR BWG AND
SDF...MAYBE LONGER AT LEX. UNDER THE CLOUDY SKIES...WINDS OUT OF THE
SSW WILL GUST UP TO 25 KTS GENERALLY. IF THE SUN CAN COME OUR OR A
FEW CLOUDS CAN CLEAR BY 18Z...THEN GUSTS THIS AFTERNOON COULD REACH
30 KTS OR PERHAPS MORE IN A FEW SPOTS BEFORE A COLD FRONT PASSES
THROUGH LATE THIS AFTERNOON.
WITH THE COLD FRONTAL PASSAGE...MORE SHRA AND TS COULD FORM ALONG IT
BUT THINK THE MAIN THREAT FOR THIS WOULD BE FOR LEX ONLY...AND
PERHAPS JUST A FEW SHOWERS WOULD AFFECT SDF OR BWG TO A LESSER
EXTENT. WITH THE FROPA...AND THROUGH THE REST OF THE TAF
PERIOD...MVFR CIGS SHOULD BE THE RULE FOR LEX...MOSTLY SDF TOO...AND
TO A LESSER EXTENT BWG. WINDS WILL VEER AROUND TO THE WNW BEHIND THE
FRONT AND WILL BE GUSTY...UP TO 20-25KTS GENERALLY.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
WEATHER.GOV/LOUISVILLE
UPDATE...13
SHORT TERM...AL
LONG TERM....LMS
AVIATION.....AL
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
614 AM EST WED FEB 18 2009
.UPDATE...
UPDATED AVIATION DISCUSSION FOR 12Z TAFS.
&&
.SHORT TERM (TODAY AND TONIGHT)...
MASS OF WARM-AIR ADVECTION SHOWERS AND STORMS ARE AFFECTING MUCH OF
THE SOUTHERN CWA. A FEW STRONG STORMS HAVE FORMED WITHIN THE
MASS...PRODUCING PEA SIZE HAIL NEAR BOWLING GREEN. ONE STORM THAT
PRODUCED NICKEL HAIL NEAR THE KY/TN BORDER MOVED ACROSS LOGAN AND
SIMPSON BUT HAS SINCE WANED. EVERYTHING NOW IS BEHAVING...WITH HEAVY
RAINFALL TRAINING OVER THE SAME AREAS...AND LOTS OF LIGHTNING. GUSTY
WINDS ARE ALSO OCCURRING...WITH PEAKS AROUND 40-45 MPH. BUT RECENT
ACARS SOUNDINGS SHOW NICE CAPPING AT 800MB...SO ANY SEVERE WIND
GUSTS MIXING DOWN SHOULD NOT OCCUR. THROUGH SUNRISE...ANY STRONG
STORM WILL BE CAPABLE OF PRODUCING PEA AND MARBLE SIZE HAIL.
THIS AREA OF SHOWERS AND STORMS IS ALL AHEAD OF AN APPROACHING LOW
PRESSURE CENTER OVER NW MISSOURI. THIS LOW WILL PUSH TOWARDS NE
INDIANA TODAY...WHICH WILL ALSO PUSH THESE SHOWERS AND STORMS EAST
OF THE CWA MOSTLY BY 18Z. THEN THE COLD FRONT FROM THE LOW WILL PASS
THROUGH THE CWA BETWEEN ROUGHLY 21Z AND 03Z. THE NMM-WRF HAS A GOOD
HANDLE ON CURRENT PRECIP...AND THAT MODEL SHOWS MORE SHOWERS/STORMS
DEVELOPING OVER OUR ERN CWA ALONG THE COLD FRONT. ASSUMING THE CAP
ALOFT CAN BREAK THIS AFTERNOON...WILL GO WITH THIS MODEL SOLUTION
AND HAVE THE HIGHEST POPS OVER THE ERN HALF OF THE CWA. DESPITE
CLOUDS AND PRECIP...TEMPS SHOULD CLIMB ESPECIALLY THIS AFTERNOON
INTO THE MID 50S N TO THE MID 60S S. WINDS WILL CONTINUE TO BE
GUSTY...ESPECIALLY LATER THIS AFTERNOON AHEAD OF THE COLD
FRONT...WITH GUSTS UP TO 35 MPH BEING POSSIBLE.
TONIGHT...ON THE BACK SIDE OF THE LOW/FRONT...TEMPS SHOULD FALL INTO
THE UPPER 20S AND LOW 30S. RESIDUAL WRAP-AROUND MOISTURE WILL AFFECT
MAINLY OUR NERN CWA OVERNIGHT...WHERE RAIN WILL CHANGE TO SNOW
SHOWERS. THIS WILL MOST LIKELY OCCUR OVER THE NORTHERN BLUEGRASS
AFTER MIDNIGHT TOWARDS DAWN THURSDAY.
.LONG TERM (THURSDAY THROUGH TUESDAY)...
NOT TOO MANY CHANGES REQUIRED THROUGH THE EXTENDED THIS MORNING.
MAIN CHALLENGES WILL BE MOVING OUT PRECIPITATION ON THURSDAY AND
ANOTHER CLIPPER SYSTEM BRINGING A CHANCE FOR LIGHT ACCUMULATING SNOW
ON SATURDAY. A WEAK DISTURBANCE ON TUESDAY NEAR THE END OF THE
FORECAST PERIOD COULD ALSO BRING ANOTHER ROUND OF PRECIPITATION.
THURSDAY THROUGH SATURDAY...
UPPER LEVEL LOW OVER MICHIGAN WILL MOVE EASTWARD INTO UPSTATE NEW
YORK PULLING SURFACE LOW INTO THE NORTHEAST U.S. NORTHWEST FLOW
ACROSS THE AREA WILL USHER IN HIGH SURFACE PRESSURE AND LINGERING
PRECIPITATION SHOULD MOVE EAST OF THE AREA BY MIDDAY WITH SOME
FLURRIES POSSIBLE ACROSS NORTH CENTRAL KY AND THE BLUEGRASS REGION
IN THE AFTERNOON BEFORE DRIER CONDITIONS SET IN THURSDAY NIGHT AND
FRIDAY. WITH HIGHS ONLY TOPPING OUT IN THE LOW 30S ON THURSDAY AND
CLEARING SKIES OVERNIGHT TEMPS WILL BOTTOM OUT IN THE TEENS BY
FRIDAY MORNING. PLENTY OF SUNSHINE ON FRIDAY AND SOME LOW LEVEL WAA
WILL ALLOW TEMPS TO REBOUND INTO THE MID 40S IN THE SOUTHWEST TO THE
UPPER 30S IN THE NORTHEAST. CLOUDS WILL INCREASE DURING THE LATE
AFTERNOON AND EARLY EVENING ON FRIDAY AS THE NEXT CLIPPER SYSTEM
APPROACHES THE AREA LATE FRIDAY NIGHT AND SATURDAY. EXPECT A MIX OF
RAIN/SNOW LATE FRIDAY EVENING MAINLY ACROSS AREAS WEST OF INTERSTATE
65 WITH PRECIPITATION SPREADING EASTWARD TOWARD SATURDAY MORNING AND
CHANGING TO ALL SNOW AFTER MIDNIGHT. EXPECT ACCUMULATION FRIDAY
NIGHT TO BE AROUND A HALF INCH IN ALL BUT THE FAR SOUTHWEST PORTIONS
OF THE FORECAST AREA WHERE LITTLE TO NO ACCUMULATION IS EXPECTED.
SNOW SHOWERS WILL CONTINUE THROUGH MIDDAY ON SATURDAY WHEN A COLD
FRONT PUSHES THROUGH AND A DRY SLOT MOVES ACROSS THE FORECAST AREA.
ADDITIONAL ACCUMULATIONS OF LESS THAN A HALF INCH ARE EXPECTED AT
THIS TIME ACROSS THE BLUEGRASS REGION OF KY. AS UPPER LOW AND
SURFACE LOW MOVE ACROSS NORTH OH AND UP THE EASTERN GREAT
LAKES...WRAP AROUND MOISTURE COUPLED WITH NORTHERLY FLOW WILL BRING
A CHANCE OF LIGHT SNOW SHOWERS TO AREAS MAINLY EAST OF INTERSTATE 75
ON SATURDAY NIGHT...LITTLE TO NO ADDITIONAL ACCUMULATIONS ARE
EXPECTED. TEMPERATURES ON SATURDAY MORNING WILL START OUT IN THE
UPPER 20S AND CLIMB TO THE MID 30S.
SUNDAY THROUGH TUESDAY...
TROUGH AXIS SWINGS THROUGH AND SHIFTS EAST OF THE AREA BY SUNDAY
MORNING AND CLEARING SKIES ARE EXPECTED. EXPECT TEMPERATURES TO BE A
FEW DEGREES COLDER DESPITE LESS CLOUD COVER AS DEEP TROUGH TO THE
EAST AND NORTHERLY FLOW OVER THE REGION ALLOWS COLDER AIR TO SEEP
SOUTHWARD. EXPECT HIGHS IN THE LOW TO MID 30S ON SUNDAY.
SURFACE HIGH PRESSURE BUILDS OVER THE SOUTHEAST STATES ON MONDAY
WITH ZONAL FLOW ALOFT ALLOWING WAA TO SET UP WITH SOUTHERLY SURFACE
FLOW. MOSTLY SUNNY SKIES WILL GIVE WAY TO INCREASING CLOUDINESS BY
LATE MONDAY AFTERNOON AS ANOTHER WEAK CLIPPER SYSTEM APPROACHES THE
AREA FOR TUESDAY. PLENTY OF MOISTURE WILL BEGIN STREAMING INTO THE
AREA FROM THE WESTERN GULF COAST OVERNIGHT MONDAY AND SHOWERS WILL
BE POSSIBLE BY TUESDAY MIDDAY AS ANOTHER COOL FRONT MAKES ITS WAY
THROUGH THE REGION. EXPECT HIGHS ON MONDAY AND TUESDAY IN THE 40S
WITH OVERNIGHT LOWS IN THE UPPER 20S TO LOW 30S.
&&
.AVIATION (12Z TAFS)...
SHOWERS/ISOLATED THUNDERSTORMS WILL CONTINUE TO AFFECT LEX AND MAYBE
BWG THROUGH 13-14Z THIS MORNING BEFORE ALL RAIN MOVES OFF TO THE
EAST. MVFR-IFR CIGS WILL CONTINUE THROUGH ABOUT 18Z FOR BWG AND
SDF...MAYBE LONGER AT LEX. UNDER THE CLOUDY SKIES...WINDS OUT OF THE
SSW WILL GUST UP TO 25 KTS GENERALLY. IF THE SUN CAN COME OUR OR A
FEW CLOUDS CAN CLEAR BY 18Z...THEN GUSTS THIS AFTERNOON COULD REACH
30 KTS OR PERHAPS MORE IN A FEW SPOTS BEFORE A COLD FRONT PASSES
THROUGH LATE THIS AFTERNOON.
WITH THE COLD FRONTAL PASSAGE...MORE SHRA AND TS COULD FORM ALONG IT
BUT THINK THE MAIN THREAT FOR THIS WOULD BE FOR LEX ONLY...AND
PERHAPS JUST A FEW SHOWERS WOULD AFFECT SDF OR BWG TO A LESSER
EXTENT. WITH THE FROPA...AND THROUGH THE REST OF THE TAF
PERIOD...MVFR CIGS SHOULD BE THE RULE FOR LEX...MOSTLY SDF TOO...AND
TO A LESSER EXTENT BWG. WINDS WILL VEER AROUND TO THE WNW BEHIND THE
FRONT AND WILL BE GUSTY...UP TO 20-25KTS GENERALLY.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
WEATHER.GOV/LOUISVILLE
SHORT TERM...AL
LONG TERM....LMS
AVIATION.....AL
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
308 AM EST WED FEB 18 2009
.SHORT TERM (TODAY AND TONIGHT)...
MASS OF WARM-AIR ADVECTION SHOWERS AND STORMS ARE AFFECTING MUCH OF
THE SOUTHERN CWA. A FEW STRONG STORMS HAVE FORMED WITHIN THE
MASS...PRODUCING PEA SIZE HAIL NEAR BOWLING GREEN. ONE STORM THAT
PRODUCED NICKEL HAIL NEAR THE KY/TN BORDER MOVED ACROSS LOGAN AND
SIMPSON BUT HAS SINCE WANED. EVERYTHING NOW IS BEHAVING...WITH HEAVY
RAINFALL TRAINING OVER THE SAME AREAS...AND LOTS OF LIGHTNING. GUSTY
WINDS ARE ALSO OCCURRING...WITH PEAKS AROUND 40-45 MPH. BUT RECENT
ACARS SOUNDINGS SHOW NICE CAPPING AT 800MB...SO ANY SEVERE WIND
GUSTS MIXING DOWN SHOULD NOT OCCUR. THROUGH SUNRISE...ANY STRONG
STORM WILL BE CAPABLE OF PRODUCING PEA AND MARBLE SIZE HAIL.
THIS AREA OF SHOWERS AND STORMS IS ALL AHEAD OF AN APPROACHING LOW
PRESSURE CENTER OVER NW MISSOURI. THIS LOW WILL PUSH TOWARDS NE
INDIANA TODAY...WHICH WILL ALSO PUSH THESE SHOWERS AND STORMS EAST
OF THE CWA MOSTLY BY 18Z. THEN THE COLD FRONT FROM THE LOW WILL PASS
THROUGH THE CWA BETWEEN ROUGHLY 21Z AND 03Z. THE NMM-WRF HAS A GOOD
HANDLE ON CURRENT PRECIP...AND THAT MODEL SHOWS MORE SHOWERS/STORMS
DEVELOPING OVER OUR ERN CWA ALONG THE COLD FRONT. ASSUMING THE CAP
ALOFT CAN BREAK THIS AFTERNOON...WILL GO WITH THIS MODEL SOLUTION
AND HAVE THE HIGHEST POPS OVER THE ERN HALF OF THE CWA. DESPITE
CLOUDS AND PRECIP...TEMPS SHOULD CLIMB ESPECIALLY THIS AFTERNOON
INTO THE MID 50S N TO THE MID 60S S. WINDS WILL CONTINUE TO BE
GUSTY...ESPECIALLY LATER THIS AFTERNOON AHEAD OF THE COLD
FRONT...WITH GUSTS UP TO 35 MPH BEING POSSIBLE.
TONIGHT...ON THE BACK SIDE OF THE LOW/FRONT...TEMPS SHOULD FALL INTO
THE UPPER 20S AND LOW 30S. RESIDUAL WRAP-AROUND MOISTURE WILL AFFECT
MAINLY OUR NERN CWA OVERNIGHT...WHERE RAIN WILL CHANGE TO SNOW
SHOWERS. THIS WILL MOST LIKELY OCCUR OVER THE NORTHERN BLUEGRASS
AFTER MIDNIGHT TOWARDS DAWN THURSDAY.
.LONG TERM (THURSDAY THROUGH TUESDAY)...
NOT TOO MANY CHANGES REQUIRED THROUGH THE EXTENDED THIS MORNING.
MAIN CHALLENGES WILL BE MOVING OUT PRECIPITATION ON THURSDAY AND
ANOTHER CLIPPER SYSTEM BRINGING A CHANCE FOR LIGHT ACCUMULATING SNOW
ON SATURDAY. A WEAK DISTURBANCE ON TUESDAY NEAR THE END OF THE
FORECAST PERIOD COULD ALSO BRING ANOTHER ROUND OF PRECIPITATION.
THURSDAY THROUGH SATURDAY...
UPPER LEVEL LOW OVER MICHIGAN WILL MOVE EASTWARD INTO UPSTATE NEW
YORK PULLING SURFACE LOW INTO THE NORTHEAST U.S. NORTHWEST FLOW
ACROSS THE AREA WILL USHER IN HIGH SURFACE PRESSURE AND LINGERING
PRECIPITATION SHOULD MOVE EAST OF THE AREA BY MIDDAY WITH SOME
FLURRIES POSSIBLE ACROSS NORTH CENTRAL KY AND THE BLUEGRASS REGION
IN THE AFTERNOON BEFORE DRIER CONDITIONS SET IN THURSDAY NIGHT AND
FRIDAY. WITH HIGHS ONLY TOPPING OUT IN THE LOW 30S ON THURSDAY AND
CLEARING SKIES OVERNIGHT TEMPS WILL BOTTOM OUT IN THE TEENS BY
FRIDAY MORNING. PLENTY OF SUNSHINE ON FRIDAY AND SOME LOW LEVEL WAA
WILL ALLOW TEMPS TO REBOUND INTO THE MID 40S IN THE SOUTHWEST TO THE
UPPER 30S IN THE NORTHEAST. CLOUDS WILL INCREASE DURING THE LATE
AFTERNOON AND EARLY EVENING ON FRIDAY AS THE NEXT CLIPPER SYSTEM
APPROACHES THE AREA LATE FRIDAY NIGHT AND SATURDAY. EXPECT A MIX OF
RAIN/SNOW LATE FRIDAY EVENING MAINLY ACROSS AREAS WEST OF INTERSTATE
65 WITH PRECIPITATION SPREADING EASTWARD TOWARD SATURDAY MORNING AND
CHANGING TO ALL SNOW AFTER MIDNIGHT. EXPECT ACCUMULATION FRIDAY
NIGHT TO BE AROUND A HALF INCH IN ALL BUT THE FAR SOUTHWEST PORTIONS
OF THE FORECAST AREA WHERE LITTLE TO NO ACCUMULATION IS EXPECTED.
SNOW SHOWERS WILL CONTINUE THROUGH MIDDAY ON SATURDAY WHEN A COLD
FRONT PUSHES THROUGH AND A DRY SLOT MOVES ACROSS THE FORECAST AREA.
ADDITIONAL ACCUMULATIONS OF LESS THAN A HALF INCH ARE EXPECTED AT
THIS TIME ACROSS THE BLUEGRASS REGION OF KY. AS UPPER LOW AND
SURFACE LOW MOVE ACROSS NORTH OH AND UP THE EASTERN GREAT
LAKES...WRAP AROUND MOISTURE COUPLED WITH NORTHERLY FLOW WILL BRING
A CHANCE OF LIGHT SNOW SHOWERS TO AREAS MAINLY EAST OF INTERSTATE 75
ON SATURDAY NIGHT...LITTLE TO NO ADDITIONAL ACCUMULATIONS ARE
EXPECTED. TEMPERATURES ON SATURDAY MORNING WILL START OUT IN THE
UPPER 20S AND CLIMB TO THE MID 30S.
SUNDAY THROUGH TUESDAY...
TROUGH AXIS SWINGS THROUGH AND SHIFTS EAST OF THE AREA BY SUNDAY
MORNING AND CLEARING SKIES ARE EXPECTED. EXPECT TEMPERATURES TO BE A
FEW DEGREES COLDER DESPITE LESS CLOUD COVER AS DEEP TROUGH TO THE
EAST AND NORTHERLY FLOW OVER THE REGION ALLOWS COLDER AIR TO SEEP
SOUTHWARD. EXPECT HIGHS IN THE LOW TO MID 30S ON SUNDAY.
SURFACE HIGH PRESSURE BUILDS OVER THE SOUTHEAST STATES ON MONDAY
WITH ZONAL FLOW ALOFT ALLOWING WAA TO SET UP WITH SOUTHERLY SURFACE
FLOW. MOSTLY SUNNY SKIES WILL GIVE WAY TO INCREASING CLOUDINESS BY
LATE MONDAY AFTERNOON AS ANOTHER WEAK CLIPPER SYSTEM APPROACHES THE
AREA FOR TUESDAY. PLENTY OF MOISTURE WILL BEGIN STREAMING INTO THE
AREA FROM THE WESTERN GULF COAST OVERNIGHT MONDAY AND SHOWERS WILL
BE POSSIBLE BY TUESDAY MIDDAY AS ANOTHER COOL FRONT MAKES ITS WAY
THROUGH THE REGION. EXPECT HIGHS ON MONDAY AND TUESDAY IN THE 40S
WITH OVERNIGHT LOWS IN THE UPPER 20S TO LOW 30S.
&&
.AVIATION (06Z TAFS)...
MVFR-IFR CIGS WILL CONTINUE TO AFFECT ALL TAF SITES. SCATTERED
SHOWERS WILL AFFECT MOST TAF LOCATIONS...WITH THUNDERSTORMS PUSHING
INTO THE AREA FROM THE SOUTHWEST. ISOLATED THUNDERSTORMS MAY AFFECT
SDF AND LEX...BUT BWG WILL MOSTLY BE IMPACTED BY THE THUNDERSTORMS.
VSBYS MAY DROP DOWN TO IFR IN THE HEAVIEST STORMS. GUSTY SSW WINDS
WILL CONTINUE TO GUST UP TO 20-25 KTS AT TIMES...WITH HIGHER GUSTS
NEAR THUNDERSTORMS.
THE HEAVIER SHRA AND TS WILL MOVE EAST OF THE AREA BY 14Z-16Z...WITH
ISOLATED SHRA CONTINUING AFTER THAT. AT THAT TIME...WINDS WILL VEER
AROUND WEST AND WILL CONTINUE TO BE GUSTY TO 25-30KTS AT TIMES.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
WEATHER.GOV/LOUISVILLE
SHORT TERM...AL
LONG TERM....LMS
AVIATION.....AL
AREA FORECAST DISCUSSION
NWS SPRINGFIELD MO
506 PM CST THU FEB 19 2009
.UPDATE...
WITH A COMBINATION OF GUSTY SOUTHWEST WINDS...TEMPERATURES
CLIMBING TO THE MID 50S TO NEAR 60...AND MINIMUM AFTERNOON
HUMIDITIES TOMORROW AFTERNOON...HAVE DECIDED TO INCLUDE A
HEIGHTENED FIRE WEATHER THREAT INTO THE HWO FOR TOMORROW
AFTERNOON. HAVE UPDATED THE HWO AND FWF FOR THE HEIGHTENED WORDING.
CLAYCOMB
&&
.DISCUSSION...
MAIN FORECAST HIGHLIGHTS/CHALLENGES IN THIS PACKAGE WILL DEAL
WITH TEMPERATURES TONIGHT THROUGH THE WEEKEND AS WARMER AIR MOVES
INTO THE AREA LATE TONIGHT INTO FRIDAY...THEN TURNING COLDER AGAIN
THIS WEEKEND. THERE WILL ALSO BE A CHANCE FOR LIGHT SNOW FRIDAY
NIGHT INTO SATURDAY MORNING. ATTENTION TURNS TO A WARMING TREND
NEXT WEEK WITH CHANCES FOR RAIN LATE IN THE LONG TERM PERIOD.
SHORT TERM (TONIGHT THROUGH SATURDAY NIGHT)...
TEMPERATURES HAVE REMAINED QUITE COOL TODAY DESPITE PLENTY OF
SUNSHINE AND AND SURFACE HIGH PRESSURE OVER THE REGION. THIS HIGH
PRESSURE IS CURRENTLY LOCATED TO THE SOUTHWEST OF THE AREA AND
WILL CONTINUE TO SHIFT TO THE EAST THIS EVENING INTO THE OVERNIGHT
HOURS. WINDS WILL BECOME LIGHT THIS EVENING AS THE HIGH SHIFTS
EAST. CLEAR SKIES AND LIGHT WINDS WILL RESULT IN GOOD RADIATIONAL
COOLING CONDITIONS...WITH TEMPERATURES QUICKLY COOLING AFTER
SUNSET. AS THE HIGH MOVES EAST...WINDS SHOULD BEGIN TO SHIFT TO
THE SOUTHEAST ACROSS THE WESTERN CWA EARLY FRIDAY MORNING. THIS
MAY STEADY LOWS OFF A BIT FOR AREAS ACROSS FAR WESTERN MISSOURI
AND SOUTHEAST KANSAS. THE QUESTION IS JUST HOW MUCH WILL THEY COOL
BEFORE THE WINDS BECOME OUT OF THE SOUTHWEST. THE EASTERN CWA
SHOULD NOT SEE THIS SOUTHERLY WINDS UNTIL LATER FRIDAY
MORNING...SO CENTRAL AND SOUTH CENTRAL MISSOURI SHOULD NOT HAVE
MUCH PROBLEMS FALLING INTO THE TEENS OVERNIGHT. WITH THE GOOD
SETUP FOR RATIONAL COOLING TONIGHT HAVE UNDER CUT MOS GUIDANCE
AREAWIDE.
WARM AIR ADVECTION WILL BE IN FULL GEAR TOMORROW AS BREEZY
SOUTHWESTERLY WINDS DEVELOP OVER THE AREA. HIGHS SHOULD WARM INTO
THE 50S ACROSS THE ENTIRE AREA...WITH 60S POSSIBLE ACROSS
SOUTHEAST KANSAS AND FAR WESTERN MISSOURI. AS TEMPERATURES WARM
TOMORROW AFTERNOON...HUMIDITY WILL FALL TO AROUND 30 PERCENT.
SOUTHERLY WINDS WILL INCREASE WITH GUSTS OF 20 TO 30 MPH POSSIBLE
AT TIMES LATE TOMORROW MORNING INTO TOMORROW AFTERNOON. THESE
CONDITIONS COULD LEAD TO SOME FIRE WEATHER CONCERNS ACROSS
SOUTHEAST KANSAS AND FAR WESTERN MISSOURI.
THE WARM UP WILL BE SHORT LIVED AS ANOTHER UPPER LEVEL DISTURBANCE
AND COLD FRONT WILL PUSH THROUGH THE AREA DURING THE OVERNIGHT
HOURS TOMORROW NIGHT. MOISTURE WILL BE LIMITED...HOWEVER THERE
SHOULD BE ENOUGH LIFT TO SQUEEZE OUT SOME FLURRIES ACROSS THE
ENTIRE AREA...WITH SLIGHTLY BETTER CHANCES FOR LIGHT SNOW ACROSS
CENTRAL AND SOUTH CENTRAL MISSOURI CLOSE TO THE BETTER DYNAMICS
ASSOCIATED WITH THE UPPER LEVEL DISTURBANCE. LITTLE TO NO
ACCUMULATIONS ARE EXPECTED...WITH NOT MUCH MORE THAN A DUSTING
EXPECTED. COOLER TEMPERATURES WILL FILTER INTO THE AREA
SATURDAY...WITH HIGHS ONLY WARMING INTO THE 30S AND LOWS FALLING
INTO THE TEENS AREA WIDE SATURDAY NIGHT.
WISE
LONG TERM (SUNDAY THROUGH THURSDAY)...
MED RANGE MODEL OUTPUT AND ENSEMBLES CONTINUE TO AGREE IN
TRANSITIONING THE UPPER PATTERN TO MORE ZONAL IN NATURE. AS IS
TYPICAL...ANY DIFFERENCES LIE WITH SMALLER SCALE FEATURES AND
TIMING OF ANY WAVES MOVING THROUGH THE FLOW.
TEMPERATURES WILL DEFINITELY MODERATE NEXT WEEK...WITH ABOVE AVERAGE
READINGS EXPECTED. THERE IS A POTENTIAL TO BE WELL ABOVE AVERAGE...
PARTICULARLY TUE/WED...THOUGH HAVE TAKEN A SLIGHTLY MORE
CONSERVATIVE APPROACH AS GRADUALLY INCREASING MOISTURE COULD LEAD TO
MORE IN THE WAY OF CLOUD COVERAGE. FOR THE PAST FEW DAYS...THE MED
RANGE MODEL OUTPUT HAS PERPETUALLY CONFINED RAIN BEARING POPS TO
THE DAY 7 TIME FRAME...TODAY IS NO DIFFERENT. HAVE GONE AHEAD AND
REMOVED POPS FOR THE MON/TUE TIME FRAME AND KEPT NEAR CLIMO POPS
FOR WED/THUR.
GAGAN
&&
.AVIATION...
FOR THE 00Z KJLN/KSGF TAFS...VFR CONDITIONS ARE EXPECTED FOR THE
NEXT 24 HOURS AT BOTH TAF SITES. LOOK FOR WINDS TO SWITCH TO THE
SOUTHWEST EARLY FRIDAY MORNING AND BECOME GUSTY BY LATE MORNING
INTO THE AFTERNOON. THIS COULD LEAD TO SOME TURBULENT LOW LEVELS
FOR SMALLER AIRCRAFT ARRIVING AND DEPARTING BOTH AIRFIELDS.
CLAYCOMB
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1010 PM EST THU FEB 19 2009
.SYNOPSIS...
DRY AND CHILLY CONDITIONS WILL PREVAIL THROUGH SATURDAY AS HIGH
PRESSURE BUILDS FROM THE PLAINS STATES INTO THE SOUTHEAST PORTION OF
THE NATION. AN UPPER LEVEL DISTURBANCE AND SURFACE COLD FRONT WILL
BRING SOME CLOUDS AND PRECIPITATION CHANCES ON SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 1010 PM THURSDAY...
HIGH PRESSURE WILL BUILD INTO THE SOUTHEAST U.S. FROM THE PLAINS
OVERNIGHT. THE COMBINATION OF THIS PRESSURE SYSTEM AND AN UPPER
LEVEL TROUGH MOVING OVER THE REGION... WILL RESULT IN WINDS STAYING
UP INTO THE EARLY MORNING HOURS. WITH THE ATMOSPHERE STAYING MIXED
OVERNIGHT... LOWS WILL RANGE FROM THE LOW AND MID 20S ACROSS THE
NORTH TO THE UPPER 20S ACROSS THE SOUTH.
FRIDAY... HIGH PRESSURE IS EXPECTED TO SETTLE ACROSS THE GULF COAST
STATES AND EXTEND INTO OUR REGION AS FLOW ALOFT BECOMES ZONAL. THIS
WILL LEAD TO ANOTHER SUNNY AND DRY DAY ACROSS THE REGION. HOWEVER...
WITH LOW LEVEL THICKNESS VALUES PROGGED TO BE START OUT IN THE 1260
RANGE AT 12Z... EXPECT HIGH WILL BE QUITE CHILLY. HAVE CONTINUED TO
GO WITH HIGHS IN THE LOWER 40S IN THE NORTHWEST TO UPPER 40S IN THE
SOUTH. THESE HIGH TEMPS ARE IN GOOD AGREEMENT WITH THE DRY ADIABATIC
LOW LEVEL THICKNESS SCHEME.
THE HIGH BEGINS TO SHIFT OFFSHORE ON FRIDAY NIGHT AS A COLD FRONT
APPROACHES THE REGION FROM THE WEST. HOWEVER... DUE TO THE PROXIMITY
OF THE HIGH... WINDS ARE FORECAST TO GO CALM... WITH ONLY A
SCATTERING OF HIGH LEVEL COULD POSSIBLE. THIS WILL LEAD TO EXCELLENT
RADIATIONAL COOLING CONDITIONS. DESPITE LOW LEVEL THICKNESS VALUES
ONLY DIPPING TO NEAR 1290 METERS... TEMPS WILL STILL PLUMMET. EXPECT
LOWS TEMPS TO RANGE FROM THE LOWER 20S NORTH TO MID 20S SOUTH.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 255 PM THURSDAY...
TEMPERATURES REBOUND NICELY ON SATURDAY AS RETURN FLOW WILL RESULT
IN SWLY WAA THROUGHOUT THE DAY...WITH ONLY MODEST MOISTURE RETURN AS
SFC DEWPOINTS CLIMB INTO THE UPPER 20S...HINTING AT THE LIMITED
MOISTURE AVAILABILITY AHEAD OF THE APPROACHING FRONTAL ZONE.
THICKNESSES SUPPORT HIGHS IN THE 53 TO 58F RANGE...WITH A TYPICAL NW
TO SE TEMPERATURE SPREAD.
CLIPPER WAVE DIVES SOUTHEAST INTO THE OHIO VALLEY AND GREAT LAKES
REGION ON SATURDAY...INDUCING CYCLOGENESIS ALONG THE WAY.
THE TRAILING COLD FRONT ATTENDANT TO THE NORTHEASTWARD LIFTING
SURFACE LOW APPROACHES THE AREA LATE SATURDAY NIGHT/EARLY SUNDAY
MORNING. THE LATEST 12Z/19 NWP MODEL FOLLOWS IN LINE WITH THE
PAST SEVERAL MODEL RUNS...INDICATING A LESS AMPLIFIED/LESS PHASED
SOLUTION...WITH NORTHERN STREAM DOMINANCE. AS PREVIOUSLY ELUDED
TO...MOISTURE TRANSPORT INTO THE CAROLINAS REMAINS LIMITED AHEAD OF
THE APPROACHING NORTHERN STREAM TROUGH...WITH MODELS INDICATING A
NARROW RIBBON OF MOISTURE ALONG THE FRONT...SPREADING INTO THE
CAROLINAS LATE SATURDAY NIGHT/EARLY SUNDAY. MID-LEVEL DYNAMICAL
SUPPORT IN THE FORM DPVA...LAGS THE DEEPEST MOISTURE AND 850MB
LOW-LEVEL CONVERGENCE WHICH SPREADS ACROSS THE AREA BETWEEN 06Z TO
15Z SUNDAY. THE NAM IS AN OUTLIER IN RESPECTS TO THE QPF AND
MOISTURE THROUGH THE COLUMN...BY FAR THE WETTEST OF THE MODELS
SPITTING OUT A 0.10 TO 0.20" OF AN INCH ACROSS THE AREA...WHILE THE
GFS...EC AND CANADIAN BARELY SQUEEZE OUT A HUNDREDTH OF AN INCH. AS
ONE WOULD EXPECT...THESE DIFFERENCES IMPACT THE PRECIP TYPE...AS THE
WETTER NAM FORECAST SOUNDINGS INDICATE ICE INTRODUCTION INTO THE
CLOUD LAYER....WHILE THE DRIER GFS SUPPORTS ONLY SUPERCOOLED WATER
DROPLETS. NEAR FREEZING SURFACE WET-BULB TEMPERATURES REMAIN ACROSS
NORTHERN PORTIONS OF THE PIEDMONT AND COASTAL PLAIN REGIONS...OR
NORTH AND WEST OF A LINE THAT EXTENDS FROM ALBEMARLE...THROUGH THE
TRIANGLE...TO ROANOKE RAPIDS. GIVEN THE NAM IS AN OUTLIER...WILL
KEEP PRECIP CHANCES IN THE SLIGHT TO LOW CHANCE CATEGORY...KEEPING A
MENTION OF RAIN OR SNOW NEAR IN THE AREA OUTLINED ABOVE. OVERNIGHT
LOWS IN THE LOWER 30S NW TO UPPER 30S SOUTHEAST.
TOUGH CALL ON TEMPERATURES SUNDAY...AS DOWNSLOPE COMPRESSIONAL
WARMING SHOULD INITIALLY OFFSET MILD CAA. BREEZY WNW WINDS WITH WIND
GUSTS OF 25 TO 30 MPH. HIGHS IN THE IN MID TO UPPER 40S NORTH TO
LOWER TO MID 50S SOUTHEAST. COLD SUNDAY NIGHT AS WINDS DECOUPLE
AS CANADIAN HIGH BUILDS IN FROM THE NORTHWEST. LOWS IN THE LOWER TO
MIDDLE 20S.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 245 AM THURSDAY...
EASTERN US TROUGH WILL LIFT OUT ON TUESDAY AS COLD CANADIAN HIGH
PRESSURE BUILDS SOUTHEAST OVER THE REGION. THIS WILL RESULT IN
BELOW NORMAL TEMPERATURES MONDAY AND TUESDAY...MODIFYING TO NEAR
NORMAL BY WEDNESDAY WITH ZONAL FLOW ALOFT AND HIGH PUSHING
OFFSHORE.
MOISTURE AND CLOUDS WILL BEGIN TO INCREASE LATE WEDNESDAY AND INTO
THURSDAY AS A S/W TROUGH SWINGS EAST THROUGH THE GREAT LAKES AND
NEW ENGLAND. SURFACE WARM FRONT AND ASSOCIATED ISENTROPIC LIFT
APPEAR TO REMAIN WEST OF THE APPALACHIANS...WITH RAIN CHANCES
INCREASING LATE THURSDAY WITH THE APPROACH OF THE COLD FRONT.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 710 PM THURSDAY...
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF FORECAST PERIOD WITH NO
CIGS AND NO VSBY RESTRICTIONS. WINDS REMAIN BLUSTERY FROM THE NW
EARLY THIS EVENING... AS AMDAR AIRCRAFT SOUNDINGS ARE SHOWING A DEEP
SURFACE BASED MIXED LAYER UP TO AROUND 7000 FT AGL. THUS... HAVE
RETAINED SUSTAINED WINDS OF 9-13 KTS WITH GUSTS OF 18-25 KTS THROUGH
MID EVENING. FOR THE REST OF THE NIGHT... THE PRESSURE GRADIENT
BETWEEN THE INCOMING SURFACE HIGH PRESSURE BUILDING FROM THE LOWER
MISSISSIPPI VALLEY INTO THE SOUTHEAST STATES AND THE INTENSE SURFACE
LOW PRESSURE NEAR THE MAINE COAST WILL KEEP THE BOUNDARY LAYER
STIRRED OVERNIGHT... AND NW WINDS SHOULD HOLD UP AOA 7 KTS AS
FORECAST SOUNDINGS SHOW MIXING PERSISTING UP TO AROUND 3000 FT AGL.
THE GUSTS TO AROUND 20 KTS WILL RETURN AFTER DAYBREAK FRIDAY WITH
BRISK NW WINDS ALOFT PERSISTING... HOWEVER THESE WINDS WILL DIMINISH
IN THE LATE AFTERNOON AS THE SURFACE HIGH PUSHES OVER THE SOUTHEAST
STATES LATE IN THE DAY.
LOOKING BEYOND EARLY FRIDAY EVENING... VFR CONDITIONS WILL HOLD
THROUGH SATURDAY. AN APPROACHING MID LEVEL SHORTWAVE TROUGH AND
ASSOCIATED SURFACE LOW WILL DROP FROM SASKATCHEWAN AND THROUGH THE
DAKOTAS AND GREAT LAKES THROUGH SUNDAY NIGHT... AND A TRAILING
DISTURBANCE WILL DROP THROUGH THE UPPER MIDWEST SATURDAY NIGHT AND
SWING RAPIDLY THROUGH VA/NRN NC BY SUNDAY AFTERNOON. FROM LATE
SATURDAY NIGHT THROUGH SUNDAY MORNING... A BRIEF PERIOD OF MVFR CIGS
ARE POSSIBLE... ALONG WITH SCATTERED RAIN OR SNOW SHOWERS. AT THIS
TIME... ANY PRECIPITATION OR VIRGA IS EXPECTED TO BE SHORT LIVED.
DRY AIR WILL RUSH IN FOR LATE SUNDAY AFTERNOON... HELPING TO CLEAR
OUT SKIES. OTHERWISE... VFR CONDITIONS ARE EXPECTED THROUGH TUESDAY
AS LARGE HIGH PRESSURE BUILDS OVER THE REGION. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...RHJ
SHORT TERM...BL
LONG TERM...BL
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
712 PM EST THU FEB 19 2009
.SYNOPSIS...
DRY AND CHILLY CONDITIONS WILL PREVAIL THROUGH SATURDAY AS HIGH
PRESSURE BUILDS FROM THE PLAINS STATES INTO THE SOUTHEAST PORTION OF
THE NATION. AN UPPER LEVEL DISTURBANCE AND SURFACE COLD FRONT WILL
BRING SOME CLOUDS CLOUDS AND PRECIPITATION CHANCES ON SUNDAY.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
AS OF 215 PM THURSDAY...
TEMPERATURES THIS AFTERNOON HAVE STALLED GENERALLY IN THE UPPER 40S
ACROSS THE TRIAD TO NEAR 60 IN THE SOUTHEAST... AS DOWNSLOPE FLOW
HAS WEAKENED. THUS... ALLOWING CAA HAS PUT A STOP TO THE NORMAL
DIURNAL TEMPERATURE CURVE WE ARE ACCUSTOM TO SEEING. THE DEEP UPPER
LEVEL L/W TROUGH OVER THE EASTER U.S. AND DAYTIME HEATING HAS CAUSED
A SOME FLAT CUMULUS TO DEVELOP THIS AFTERNOON. WINDS THIS AFTERNOON
CONTINUE TO BE OUT OF THE WNW AT AROUND 15 TO 20 MPH... WITH A FEW
GUSTS AS HIGH AS 30 MPH. THIS TREND SHOULD CONTINUE FOR THE
REMAINDER OF THE DAY... AS SOME OF THE HIGHER WIND SPEEDS ALOFT HAVE
MOVED EAST THE AREA WITH THE DEPARTING SYSTEM.
FOR TONIGHT HIGH PRESSURE AT THE SURFACE WILL BUILD INTO THE AREA...
AS ANOTHER UPPER LEVEL DISTURBANCE PASSES OVERHEAD. EXPECT THE S/W
ALOFT TO PASS THROUGH THE REGION TONIGHT WITH LITTLE FANFARE. NO
PRECIP IS EXPECT... AND SKIES ARE EXPECTED TO BE MOSTLY CLEAR. WINDS
WILL LIKELY STAY IN THE 5 TO 10 MPH RANGE TONIGHT AS THE MSLP
GRADIENT REMAINS SOMEWHAT TIGHT AND THE LOW LEVEL OF THE ATMOSPHERE
REMAIN A BIT MIXED. LOW TEMPS TONIGHT LOOK TO BE ON THE CHILLY TO
COLD SIDE... WITH LOW LEVEL THICKNESS VALUES FALLING TO AROUND 1260
METERS BY 12Z FRIDAY. LOW LEVEL THICKNESS VALUES THIS LOW TYPICALLY
RESULT IN LOW TEMPS OF AROUND 20 OR IN THE UPPER TEEN AT KGSO.
HOWEVER... WITH WIND NOT EXPECTED TO GO CALM... THINK TEMPS WILL BE
A BIT WARMER THAN LOW LEVEL THICKNESS DATABASE WOULD SUGGEST.
THUS... EXPECT OVERNIGHT LOWS TO BE IN THE LOWER 20S IN THE
NORTHWEST TO MID TO UPPER 20S ELSEWHERE.
ON FRIDAY... HIGH PRESSURE IS EXPECTED TO SETTLE ACROSS THE GULF
COAST STATES AND EXTEND INTO OUR REGION AS FLOW ALOFT BECOMES
ZONAL. THIS WILL LEAD TO ANOTHER SUNNY AND DRY DAY ACROSS THE
REGION. HOWEVER... WITH LOW LEVEL THICKNESS VALUES PROGGED TO BE
START OUT IN THE 1260 RANGE AT 12Z... EXPECT HIGH WILL BE QUITE
CHILLY. HAVE CONTINUED TO GO WITH HIGHS IN THE LOWER 40S IN THE
NORTHWEST TO UPPER 40S IN THE SOUTH. THESE HIGH TEMPS ARE IN GOOD
AGREEMENT WITH THE DRY ADIABATIC LOW LEVEL THICKNESS SCHEME.
THE HIGH BEGINS TO SHIFT OFFSHORE ON FRIDAY NIGHT AS A COLD FRONT
APPROACHES THE REGION FROM THE WEST. HOWEVER... DUE TO THE PROXIMITY
OF THE HIGH... WINDS ARE FORECAST TO GO CALM... WITH ONLY A
SCATTERING OF HIGH LEVEL COULD POSSIBLE. THIS WILL LEAD TO EXCELLENT
RADIATIONAL COOLING CONDITIONS. DESPITE LOW LEVEL THICKNESS VALUES
ONLY DIPPING TO NEAR 1290 METERS... TEMPS WILL STILL PLUMMET. EXPECT
LOWS TEMPS TO RANGE FROM THE LOWER 20S NORTH TO MID 20S SOUTH.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
AS OF 255 PM THURSDAY...
TEMPERATURES REBOUND NICELY ON SATURDAY AS RETURN FLOW WILL RESULT
IN SWLY WAA THROUGHOUT THE DAY...WITH ONLY MODEST MOISTURE RETURN AS
SFC DEWPOINTS CLIMB INTO THE UPPER 20S...HINTING AT THE LIMITED
MOISTURE AVAILABILITY AHEAD OF THE APPROACHING FRONTAL ZONE.
THICKNESSES SUPPORT HIGHS IN THE 53 TO 58F RANGE...WITH A TYPICAL NW
TO SE TEMPERATURE SPREAD.
CLIPPER WAVE DIVES SOUTHEAST INTO THE OHIO VALLEY AND GREAT LAKES
REGION ON SATURDAY...INDUCING CYCLOGENESIS ALONG THE WAY.
THE TRAILING COLD FRONT ATTENDANT TO THE NORTHEASTWARD LIFTING
SURFACE LOW APPROACHES THE AREA LATE SATURDAY NIGHT/EARLY SUNDAY
MORNING. THE LATEST 12Z/19 NWP MODEL FOLLOWS IN LINE WITH THE
PAST SEVERAL MODEL RUNS...INDICATING A LESS AMPLIFIED/LESS PHASED
SOLUTION...WITH NORTHERN STREAM DOMINANCE. AS PREVIOUSLY ELUDED
TO...MOISTURE TRANSPORT INTO THE CAROLINAS REMAINS LIMITED AHEAD OF
THE APPROACHING NORTHERN STREAM TROUGH...WITH MODELS INDICATING A
NARROW RIBBON OF MOISTURE ALONG THE FRONT...SPREADING INTO THE
CAROLINAS LATE SATURDAY NIGHT/EARLY SUNDAY. MID-LEVEL DYNAMICAL
SUPPORT IN THE FORM DPVA...LAGS THE DEEPEST MOISTURE AND 850MB
LOW-LEVEL CONVERGENCE WHICH SPREADS ACROSS THE AREA BETWEEN 06Z TO
15Z SUNDAY. THE NAM IS AN OUTLIER IN RESPECTS TO THE QPF AND
MOISTURE THROUGH THE COLUMN...BY FAR THE WETTEST OF THE MODELS
SPITTING OUT A 0.10 TO 0.20" OF AN INCH ACROSS THE AREA...WHILE THE
GFS...EC AND CANADIAN BARELY SQUEEZE OUT A HUNDREDTH OF AN INCH. AS
ONE WOULD EXPECT...THESE DIFFERENCES IMPACT THE PRECIP TYPE...AS THE
WETTER NAM FORECAST SOUNDINGS INDICATE ICE INTRODUCTION INTO THE
CLOUD LAYER....WHILE THE DRIER GFS SUPPORTS ONLY SUPERCOOLED WATER
DROPLETS. NEAR FREEZING SURFACE WET-BULB TEMPERATURES REMAIN ACROSS
NORTHERN PORTIONS OF THE PIEDMONT AND COASTAL PLAIN REGIONS...OR
NORTH AND WEST OF A LINE THAT EXTENDS FROM ALBEMARLE...THROUGH THE
TRIANGLE...TO ROANOKE RAPIDS. GIVEN THE NAM IS AN OUTLIER...WILL
KEEP PRECIP CHANCES IN THE SLIGHT TO LOW CHANCE CATEGORY...KEEPING A
MENTION OF RAIN OR SNOW NEAR IN THE AREA OUTLINED ABOVE. OVERNIGHT
LOWS IN THE LOWER 30S NW TO UPPER 30S SOUTHEAST.
TOUGH CALL ON TEMPERATURES SUNDAY...AS DOWNSLOPE COMPRESSIONAL
WARMING SHOULD INITIALLY OFFSET MILD CAA. BREEZY WNW WINDS WITH WIND
GUSTS OF 25 TO 30 MPH. HIGHS IN THE IN MID TO UPPER 40S NORTH TO
LOWER TO MID 50S SOUTHEAST. COLD SUNDAY NIGHT AS WINDS DECOUPLE
AS CANADIAN HIGH BUILDS IN FROM THE NORTHWEST. LOWS IN THE LOWER TO
MIDDLE 20S.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
AS OF 245 AM THURSDAY...
EASTERN US TROUGH WILL LIFT OUT ON TUESDAY AS COLD CANADIAN HIGH
PRESSURE BUILDS SOUTHEAST OVER THE REGION. THIS WILL RESULT IN
BELOW NORMAL TEMPERATURES MONDAY AND TUESDAY...MODIFYING TO NEAR
NORMAL BY WEDNESDAY WITH ZONAL FLOW ALOFT AND HIGH PUSHING
OFFSHORE.
MOISTURE AND CLOUDS WILL BEGIN TO INCREASE LATE WEDNESDAY AND INTO
THURSDAY AS A S/W TROUGH SWINGS EAST THROUGH THE GREAT LAKES AND
NEW ENGLAND. SURFACE WARM FRONT AND ASSOCIATED ISENTROPIC LIFT
APPEAR TO REMAIN WEST OF THE APPALACHIANS...WITH RAIN CHANCES
INCREASING LATE THURSDAY WITH THE APPROACH OF THE COLD FRONT.
&&
.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
AS OF 710 PM THURSDAY...
VFR CONDITIONS ARE EXPECTED THROUGH THE TAF FORECAST PERIOD WITH NO
CIGS AND NO VSBY RESTRICTIONS. WINDS REMAIN BLUSTERY FROM THE NW
EARLY THIS EVENING... AS AMDAR AIRCRAFT SOUNDINGS ARE SHOWING A DEEP
SURFACE BASED MIXED LAYER UP TO AROUND 7000 FT AGL. THUS... HAVE
RETAINED SUSTAINED WINDS OF 9-13 KTS WITH GUSTS OF 18-25 KTS THROUGH
MID EVENING. FOR THE REST OF THE NIGHT... THE PRESSURE GRADIENT
BETWEEN THE INCOMING SURFACE HIGH PRESSURE BUILDING FROM THE LOWER
MISSISSIPPI VALLEY INTO THE SOUTHEAST STATES AND THE INTENSE SURFACE
LOW PRESSURE NEAR THE MAINE COAST WILL KEEP THE BOUNDARY LAYER
STIRRED OVERNIGHT... AND NW WINDS SHOULD HOLD UP AOA 7 KTS AS
FORECAST SOUNDINGS SHOW MIXING PERSISTING UP TO AROUND 3000 FT AGL.
THE GUSTS TO AROUND 20 KTS WILL RETURN AFTER DAYBREAK FRIDAY WITH
BRISK NW WINDS ALOFT PERSISTING... HOWEVER THESE WINDS WILL DIMINISH
IN THE LATE AFTERNOON AS THE SURFACE HIGH PUSHES OVER THE SOUTHEAST
STATES LATE IN THE DAY.
LOOKING BEYOND EARLY FRIDAY EVENING... VFR CONDITIONS WILL HOLD
THROUGH SATURDAY. AN APPROACHING MID LEVEL SHORTWAVE TROUGH AND
ASSOCIATED SURFACE LOW WILL DROP FROM SASKATCHEWAN AND THROUGH THE
DAKOTAS AND GREAT LAKES THROUGH SUNDAY NIGHT... AND A TRAILING
DISTURBANCE WILL DROP THROUGH THE UPPER MIDWEST SATURDAY NIGHT AND
SWING RAPIDLY THROUGH VA/NRN NC BY SUNDAY AFTERNOON. FROM LATE
SATURDAY NIGHT THROUGH SUNDAY MORNING... A BRIEF PERIOD OF MVFR CIGS
ARE POSSIBLE... ALONG WITH SCATTERED RAIN OR SNOW SHOWERS. AT THIS
TIME... ANY PRECIPITATION OR VIRGA IS EXPECTED TO BE SHORT LIVED.
DRY AIR WILL RUSH IN FOR LATE SUNDAY AFTERNOON... HELPING TO CLEAR
OUT SKIES. OTHERWISE... VFR CONDITIONS ARE EXPECTED THROUGH TUESDAY
AS LARGE HIGH PRESSURE BUILDS OVER THE REGION. -GIH
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SYNOPSIS...HARTFIELD
NEAR TERM...BSD
SHORT TERM...BL
LONG TERM...BL
AVIATION...HARTFIELD
AREA FORECAST DISCUSSION...UPDATED
NWS BLACKSBURG VA
1116 AM EST WED FEB 18 2009
.SYNOPSIS...
A WINTER STORM WILL MOVE THROUGH THE GREAT LAKES AND OHIO VALLEY
TODAY...WITH ITS ASSOCIATED COLD FRONT PASSING EAST ACROSS THE
MID ATLANTIC REGION...SPREADING RAIN AND A BRIEF PERIOD OF WINTRY
MIX TO THE REGION. THE COLD FRONT WILL MOVE EAST OF THE AREA
TONIGHT AS THE WINTER STORM MOVE INTO NEW ENGLAND. COLDER AND
WINDY CONDITIONS WILL DEVELOP BEHIND THE FRONT WITH MOUNTAIN SNOW
SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPDATE TO REMOVE GOING ADVISORIES AS TEMPS HAVE CLIMBED ABOVE
FREEZING IN MOST SPOTS WITH ONLY SPOTTY PRECIP REMAINING.
INITIAL FAST MOVING SLUG OF MIXED PRECIP WITH FRONT ALOFT HAS
RACED INTO THE FAR NORTHERN/EASTERN PORTIONS OF THE CWA WITH MORE
SCATTERED NATURE -RA TO THE WEST. NOSE OF JET ALOFT AND THE
ASSOCIATED UPPER DIFFLUENCE LIKELY TO BE THE MAIN PLAYER FOR
ADDITIONAL PRECIP THRU THE AFTERNOON...WELL IN ADVANCE OF THE
COLD FRONT NEARING THE MISS RIVER. LATEST WRF SHOWS MUCH OF THE
ADDED SHRA ACROSS THE WEST WHERE CAN TOTALLY RULE OUT SOME
EMBEDDED THUNDER ALONG INSTABILITY AXIS ESPCLY FAR WESTERN SLOPES
ON THE PERIMETER OF THE INSITU WEDGE. OTRW PLAN TO LOWER POPS SOME
ESPCLY AFTER 18Z WHEN THE LATEST 12Z NAM HAS QUITE A DRY SLOT
WORKING IN WITH SOME BREAKS POSSIBLE WEST. NUDGED TEMPS DOWN SOME
NW WHERE HOVERING NEAR FREEZING AND OVER CENTRAL ZONES NEAR THE
BLUE RIDGE WHERE THE WEDGE IS STRONGER. SINCE ALSO STILL HAVE SOME
TEMPS NEAR FREEZING AND AT LEAST SCTD PRECIP IN THE ADVISORY
AREAS...PLAN TO LEAVE THE WSW PRODUCTS IN PLACE UNTIL NOON WHEN
WILL SEND AN UPDATED ZFP FOR THE AFTERNOON. PREVIOUS DISCUSSION
BELOW...
REGIONAL RADARS INDICATE A LARGE SWATH OF PRECIPITATION ADVANCING
EAST ACROSS TN/KY. THIS PRECIPITATION WILL ARRIVE THIS MORNING AND
WILL BE WIDESPREAD FOR AT LEAST THE FIRST HALF OF THE DAY. AT THE
ONSET...TEMPERATURES WILL SUPPORT A WINTRY MIX WITH SNOW AND
SLEET. THE PROFILE IS PROGGED TO WARM RAPIDLY ALOFT AND THINK JUST
ABOUT ALL LOCATIONS IN OUR CWA WILL TURN OVER TO PLAIN OL RAIN BY
MID MORNING. FOR THE MOST PART...THE PRECIPITATION WILL BE FALLING
INTO A BOUNDARY LAYER THAT IS ABOVE FREEZING...THUS DO NOT
ANTICIPATE ANY SIGNIFICANT ACCUMULATION. THE COLDEST
LOCATIONS...ALONG AND NORTH OF INTERSTATE 64 MAY EXPERIENCE AN
INCH OR TWO OF SNOW AND SLEET...BEFORE CHANGING TO FREEZING RAIN
AND THEN RAIN. FOR THIS REASON HAVE ISSUED A WINTER WEATHER
ADVISORY THIS MORNING FOR BATH...ROCKBRIDGE...AND AMHERST. HAVE
ALSO ISSUED A FREEZING RAIN ADVISORY FOR THE NORTHWEST MOUNTAINS
OF NORTH CAROLINA...INCLUDING GRAYSON AND CARROLL COUNTIES IN
VIRGINIA WHERE TEMPERATURES ARE AROUND FREEZING.
ASIDE FROM THE INSITU COLD AIR THAT IS IN PLACE ACROSS THE
CWA...THERE IS NO BLOCKING HIGH TO THE NORTH. APPROACH OF COLD
FRONT AND WARM AIR ADVECTION AHEAD OF THIS FEATURE SHOULD ALLOW
TEMPS TO STEADILY CLIMB THROUGH THE DAY...MOST AREAS CLIMBING INTO
THE 40S.
THE SURFACE FRONT IS PROGGED TO PASS THROUGH THE AREA BY MIDNIGHT
TONIGHT WITH THE SURFACE LOW MOVING INTO EASTERN ONTARIO. STRONG
COLD AIR ADVECTION WILL TAKE PLACE BEHIND THE FRONT AND THIS WILL
SET THE STAGE FOR A COLD NEXT COUPLE OF DAYS WITH MOUNTAIN SNOW
SHOWERS AND FLURRIES ALONG WITH BRISK NORTHWEST WINDS.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
BIGGEST CONCERN FOR THIS PART OF THE PACKAGE IS WINDS AND UPSLOPE
SNOW. DEBATING WHETHER OR NOT TO ISSUE AN ELEVATION WATCH FOR
GREENBRIER. HOWEVER...NAM12 H7 MOISTURE IS FARTHER NORTH AND
MOISTURE DEPTH IS MORE SHALLOW THAN THE PAST FEW NIGHTS. SEEMS AS
THOUGH THE DEEPEST MOISTURE WILL BE AROUND FROM MID MORNING THURS
THROUGH EARLY AFTERNOON. ATTM...THE BEST COURSE OF ACTION WOULD BE
A SNOW ADVISORY SAY FROM GREENBRIER TO TAZEWELL FROM THURS INTO
THURS NIGHT BUT THIS CAN BE FINE TUNED ON FUTURE SHIFTS. ABOVE
2500 FEET IN GREENBRIER MAY BE CLOSE OR JUST ABV WARNING CRITERIA
BY FRIDAY MORNING AND THIS CAN BE HANDLED IN AN ADVISORY TOO. ANOTHER
ISSUE IS THE WIND WHICH WILL BE BLOWING THE SNOW AROUND.
NONETHELESS...IT WILL BE SNOWING HARD AT TIMES WITH WINDS GREATLY
REDUCING VISIBILITIES IN THESE SPOTS THURS AND THURS NIGHT. A
COUPLE INCHES MAY ALSO FALL IN THE SKI COUNTRY OF NW NC WITH AN
INCH OR LESS AT THE LOWER ELEVATIONS. IF WINDS STAY UP...WIND CHILL
ADVISORY CRITERIA MAY BE MET INTO FRIDAY MORNING FOR THE EXTREME
SW...WHICH WILL RECEIVE THE COLDEST AIR FIRST. CONSIDERING H85
VALUES WILL BE NEAR -15C...SHALLOW ARCTIC AIRMASS...DID KEEP TEMPS
A FEW DEGREES BELOW COLDEST GUIDANCE FOR MIN/MAX ON FRIDAY. WILL ALSO
NEED A WIND ADVISORY FOR NW NC AND POSSIBLY PART OF THE BLUE RIDGE
IN VA THURSDAY AND THURSDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
TIMING OF THE SATURDAY SYSTEM IS SIMILAR TO YESTERDAY...ALTHOUGH MAY
BE SLOWER BY A FEW HOURS. STILL LOOKING AT BEST CHANCE OF PRECIP
ARRIVING IN THE WEST DURING THE DAY AND MOVING EAST BY EVENING WITH
UPSLOPE SNOW SHOWERS ON THE BACK SIDE LASTING INTO SUNDAY.
AFTER THIS THE PATTERN FLATTENS WITH A BACKDOOR FRONT STRETCHING
INTO THE MID ATLANTIC BY TUESDAY BUT NO AFFECTS IN TERM OF PRECIP
FOR OUR AREA. TEMPS WILL SLOWLY MODERATE AS SFC HIGH SETTLES ACROSS
THE AREA SUN-MON.
THE 12Z ECMWF MODEL HAS A DIFFERENT SOLUTION INTO MONDAY AS IT FORMS
A NEW LOW ALONG THE FRONT IN THE SOUTHEAST SUNDAY MORNING AND SHIFTS
IT OFF THE NORTH CAROLINA/VIRGINIA COAST BY 12Z MONDAY. THIS SYSTEM
WOULD BRING A GOOD SNOW TO PORTIONS OF THE AREA IF IT PANS OUT...BUT
ATTM...THE OTHER MODELS ARE NOT FAVORING IT.
&&
.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
RADAR RETURNS NOT PRODUCING MUCH AT THE GROUND THIS HOUR...AND
WILL PROBABLY BE THE CASE OVER THE NEXT FEW HOURS WITH VERY DRY
LLVLS. WOULD THINK THOUGH THERE IS A GOOD CHANCE FOR ICING ALOFT
OF AIRCRAFT HOWEVER WITH THIS SETUP. VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING AS HIGH PRESSURE MAINTAINS CONTROL OF OUR
AREA. OVERNIGHT...A SYSTEM WILL SWEEP THROUGH THE AREA BRINGING
MVFR/IFR CIGS AND MAINLY MVFR VSBYS STARTING BETWEEN 08-12Z FROM
WEST TO EAST. ACCOMPANYING THIS CLOUD COVER WILL BE A BRIEF SHOT
OF SNOW/SLEET/FZRA BEFORE QUICKLY CHANGING OVER TO ALL RAIN. THE
WINTRY MIX WILL LAST LONGEST AT LWB...AND SHORTEST AT BLF. AREAS
OF SOUTHEAST WEST VIRGINIA AND PARTS OF SOUTHWEST VIRGINIA ALONG
AND NORTH OF A KROA-KLYH LINE CAN EXPECT SNOW OR SLEET AT THE
ONSET OF THE PRECIPITATION FOR A FEW HOURS. ELSEWHERE...RAIN IS
EXPECTED AT THE ONSET OF THE PRECIPITATION. DURING THE MORNING
WEDNESDAY...WARMER AIR ENTERING THE REGION WILL ALLOW FOR A
TRANISTION TO ALL RAIN ACROSS THE AREA.
THE CIG/VSBY RESTRICTIONS WILL LIKELY CONTINUE THROUGH WEDNESDAY
NIGHT UNTIL A COLD FRONT MOVES THROUGH BY THURSDAY MORNING. SCT
RAIN AND SNOW SHOWERS WILL CONTINUE IN THE WESTERN MOUNTAINS IN A
COLD NORTHWEST FLOW THURSDAY AND FRIDAY. STRONG WINDS CAN BE
EXPECTED THURSDAY/THURSDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...JH/PM
NEAR TERM...JH/PM
SHORT TERM...KM
LONG TERM...WP
AVIATION...KM/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1023 AM EST WED FEB 18 2009
.SYNOPSIS...
A WINTER STORM WILL MOVE THROUGH THE GREAT LAKES AND OHIO VALLEY
TODAY...WITH ITS ASSOCIATED COLD FRONT PASSING EAST ACROSS THE
MID ATLANTIC REGION...SPREADING RAIN AND A BRIEF PERIOD OF WINTRY
MIX TO THE REGION. THE COLD FRONT WILL MOVE EAST OF THE AREA
TONIGHT AS THE WINTER STORM MOVE INTO NEW ENGLAND. COLDER AND
WINDY CONDITIONS WILL DEVELOP BEHIND THE FRONT WITH MOUNTAIN SNOW
SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
INITIAL FAST MOVING SLUG OF MIXED PRECIP WITH FRONT ALOFT HAS
RACED INTO THE FAR NORTHERN/EASTERN PORTIONS OF THE CWA WITH MORE
SCATTERED NATURE -RA TO THE WEST. NOSE OF JET ALOFT AND THE
ASSOCIATED UPPER DIFFLUENCE LIKELY TO BE THE MAIN PLAYER FOR
ADDITIONAL PRECIP THRU THE AFTERNOON...WELL IN ADVANCE OF THE
COLD FRONT NEARING THE MISS RIVER. LATEST WRF SHOWS MUCH OF THE
ADDED SHRA ACROSS THE WEST WHERE CAN TOTALLY RULE OUT SOME
EMBEDDED THUNDER ALONG INSTABILITY AXIS ESPCLY FAR WESTERN SLOPES
ON THE PERIMETER OF THE INSITU WEDGE. OTRW PLAN TO LOWER POPS SOME
ESPCLY AFTER 18Z WHEN THE LATEST 12Z NAM HAS QUITE A DRY SLOT
WORKING IN WITH SOME BREAKS POSSIBLE WEST. NUDGED TEMPS DOWN SOME
NW WHERE HOVERING NEAR FREEZING AND OVER CENTRAL ZONES NEAR THE
BLUE RIDGE WHERE THE WEDGE IS STRONGER. SINCE ALSO STILL HAVE SOME
TEMPS NEAR FREEZING AND AT LEAST SCTD PRECIP IN THE ADVISORY
AREAS...PLAN TO LEAVE THE WSW PRODUCTS IN PLACE UNTIL NOON WHEN
WILL SEND AN UPDATED ZFP FOR THE AFTERNOON. PREVIOUS DISCUSSION
BELOW...
REGIONAL RADARS INDICATE A LARGE SWATH OF PRECIPITATION ADVANCING
EAST ACROSS TN/KY. THIS PRECIPITATION WILL ARRIVE THIS MORNING AND
WILL BE WIDESPREAD FOR AT LEAST THE FIRST HALF OF THE DAY. AT THE
ONSET...TEMPERATURES WILL SUPPORT A WINTRY MIX WITH SNOW AND
SLEET. THE PROFILE IS PROGGED TO WARM RAPIDLY ALOFT AND THINK JUST
ABOUT ALL LOCATIONS IN OUR CWA WILL TURN OVER TO PLAIN OL RAIN BY
MID MORNING. FOR THE MOST PART...THE PRECIPITATION WILL BE FALLING
INTO A BOUNDARY LAYER THAT IS ABOVE FREEZING...THUS DO NOT
ANTICIPATE ANY SIGNIFICANT ACCUMULATION. THE COLDEST
LOCATIONS...ALONG AND NORTH OF INTERSTATE 64 MAY EXPERIENCE AN
INCH OR TWO OF SNOW AND SLEET...BEFORE CHANGING TO FREEZING RAIN
AND THEN RAIN. FOR THIS REASON HAVE ISSUED A WINTER WEATHER
ADVISORY THIS MORNING FOR BATH...ROCKBRIDGE...AND AMHERST. HAVE
ALSO ISSUED A FREEZING RAIN ADVISORY FOR THE NORTHWEST MOUNTAINS
OF NORTH CAROLINA...INCLUDING GRAYSON AND CARROLL COUNTIES IN
VIRGINIA WHERE TEMPERATURES ARE AROUND FREEZING.
ASIDE FROM THE INSITU COLD AIR THAT IS IN PLACE ACROSS THE
CWA...THERE IS NO BLOCKING HIGH TO THE NORTH. APPROACH OF COLD
FRONT AND WARM AIR ADVECTION AHEAD OF THIS FEATURE SHOULD ALLOW
TEMPS TO STEADILY CLIMB THROUGH THE DAY...MOST AREAS CLIMBING INTO
THE 40S.
THE SURFACE FRONT IS PROGGED TO PASS THROUGH THE AREA BY MIDNIGHT
TONIGHT WITH THE SURFACE LOW MOVING INTO EASTERN ONTARIO. STRONG
COLD AIR ADVECTION WILL TAKE PLACE BEHIND THE FRONT AND THIS WILL
SET THE STAGE FOR A COLD NEXT COUPLE OF DAYS WITH MOUNTAIN SNOW
SHOWERS AND FLURRIES ALONG WITH BRISK NORTHWEST WINDS.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
BIGGEST CONCERN FOR THIS PART OF THE PACKAGE IS WINDS AND UPSLOPE
SNOW. DEBATING WHETHER OR NOT TO ISSUE AN ELEVATION WATCH FOR
GREENBRIER. HOWEVER...NAM12 H7 MOISTURE IS FARTHER NORTH AND
MOISTURE DEPTH IS MORE SHALLOW THAN THE PAST FEW NIGHTS. SEEMS AS
THOUGH THE DEEPEST MOISTURE WILL BE AROUND FROM MID MORNING THURS
THROUGH EARLY AFTERNOON. ATTM...THE BEST COURSE OF ACTION WOULD BE
A SNOW ADVISORY SAY FROM GREENBRIER TO TAZEWELL FROM THURS INTO
THURS NIGHT BUT THIS CAN BE FINE TUNED ON FUTURE SHIFTS. ABOVE
2500 FEET IN GREENBRIER MAY BE CLOSE OR JUST ABV WARNING CRITERIA
BY FRIDAY MORNING AND THIS CAN BE HANDLED IN AN ADVISORY TOO. ANOTHER
ISSUE IS THE WIND WHICH WILL BE BLOWING THE SNOW AROUND.
NONETHELESS...IT WILL BE SNOWING HARD AT TIMES WITH WINDS GREATLY
REDUCING VISIBILITIES IN THESE SPOTS THURS AND THURS NIGHT. A
COUPLE INCHES MAY ALSO FALL IN THE SKI COUNTRY OF NW NC WITH AN
INCH OR LESS AT THE LOWER ELEVATIONS. IF WINDS STAY UP...WIND CHILL
ADVISORY CRITERIA MAY BE MET INTO FRIDAY MORNING FOR THE EXTREME
SW...WHICH WILL RECEIVE THE COLDEST AIR FIRST. CONSIDERING H85
VALUES WILL BE NEAR -15C...SHALLOW ARCTIC AIRMASS...DID KEEP TEMPS
A FEW DEGREES BELOW COLDEST GUIDANCE FOR MIN/MAX ON FRIDAY. WILL ALSO
NEED A WIND ADVISORY FOR NW NC AND POSSIBLY PART OF THE BLUE RIDGE
IN VA THURSDAY AND THURSDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
TIMING OF THE SATURDAY SYSTEM IS SIMILAR TO YESTERDAY...ALTHOUGH MAY
BE SLOWER BY A FEW HOURS. STILL LOOKING AT BEST CHANCE OF PRECIP
ARRIVING IN THE WEST DURING THE DAY AND MOVING EAST BY EVENING WITH
UPSLOPE SNOW SHOWERS ON THE BACK SIDE LASTING INTO SUNDAY.
AFTER THIS THE PATTERN FLATTENS WITH A BACKDOOR FRONT STRETCHING
INTO THE MID ATLANTIC BY TUESDAY BUT NO AFFECTS IN TERM OF PRECIP
FOR OUR AREA. TEMPS WILL SLOWLY MODERATE AS SFC HIGH SETTLES ACROSS
THE AREA SUN-MON.
THE 12Z ECMWF MODEL HAS A DIFFERENT SOLUTION INTO MONDAY AS IT FORMS
A NEW LOW ALONG THE FRONT IN THE SOUTHEAST SUNDAY MORNING AND SHIFTS
IT OFF THE NORTH CAROLINA/VIRGINIA COAST BY 12Z MONDAY. THIS SYSTEM
WOULD BRING A GOOD SNOW TO PORTIONS OF THE AREA IF IT PANS OUT...BUT
ATTM...THE OTHER MODELS ARE NOT FAVORING IT.
&&
.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
RADAR RETURNS NOT PRODUCING MUCH AT THE GROUND THIS HOUR...AND
WILL PROBABLY BE THE CASE OVER THE NEXT FEW HOURS WITH VERY DRY
LLVLS. WOULD THINK THOUGH THERE IS A GOOD CHANCE FOR ICING ALOFT
OF AIRCRAFT HOWEVER WITH THIS SETUP. VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING AS HIGH PRESSURE MAINTAINS CONTROL OF OUR
AREA. OVERNIGHT...A SYSTEM WILL SWEEP THROUGH THE AREA BRINGING
MVFR/IFR CIGS AND MAINLY MVFR VSBYS STARTING BETWEEN 08-12Z FROM
WEST TO EAST. ACCOMPANYING THIS CLOUD COVER WILL BE A BRIEF SHOT
OF SNOW/SLEET/FZRA BEFORE QUICKLY CHANGING OVER TO ALL RAIN. THE
WINTRY MIX WILL LAST LONGEST AT LWB...AND SHORTEST AT BLF. AREAS
OF SOUTHEAST WEST VIRGINIA AND PARTS OF SOUTHWEST VIRGINIA ALONG
AND NORTH OF A KROA-KLYH LINE CAN EXPECT SNOW OR SLEET AT THE
ONSET OF THE PRECIPITATION FOR A FEW HOURS. ELSEWHERE...RAIN IS
EXPECTED AT THE ONSET OF THE PRECIPITATION. DURING THE MORNING
WEDNESDAY...WARMER AIR ENTERING THE REGION WILL ALLOW FOR A
TRANISTION TO ALL RAIN ACROSS THE AREA.
THE CIG/VSBY RESTRICTIONS WILL LIKELY CONTINUE THROUGH WEDNESDAY
NIGHT UNTIL A COLD FRONT MOVES THROUGH BY THURSDAY MORNING. SCT
RAIN AND SNOW SHOWERS WILL CONTINUE IN THE WESTERN MOUNTAINS IN A
COLD NORTHWEST FLOW THURSDAY AND FRIDAY. STRONG WINDS CAN BE
EXPECTED THURSDAY/THURSDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR VAZ015-016.
WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR VAZ020-024-
035.
NC...FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NCZ001-002-018.
WV...NONE.
&&
$$
SYNOPSIS...JH/PM
NEAR TERM...JH/PM
SHORT TERM...KM
LONG TERM...WP
AVIATION...KM/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
552 AM EST WED FEB 18 2009
.SYNOPSIS...
A WINTER STORM WILL MOVE THROUGH THE GREAT LAKES AND OHIO VALLEY
TODAY. ITS ASSOCIATED COLD FRONT WILL MOVE EAST ACROSS THE MID
ATLANTIC REGION...SPREADING RAIN AND A BRIEF PERIOD OF WINTRY
MIX TO THE MID ATLANTIC REGION. THE COLD FRONT WILL MOVE EAST
OF THE AREA TONIGHT AS THE WINTER STORM MOVE INTO NEW ENGLAND.
COLDER AND WINDY CONDITIONS WILL DEVELOP BEHIND THE FRONT WITH
MOUNTAIN SNOW SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS INDICATE A LARGE SWATH OF PRECIPITATION ADVANCING
EAST ACROSS TN/KY. THIS PRECIPITATION WILL ARRIVE THIS MORNING AND
WILL BE WIDESPREAD FOR AT LEAST THE FIRST HALF OF THE DAY. AT THE
ONSET...TEMPERATURES WILL SUPPORT A WINTRY MIX WITH SNOW AND
SLEET. THE PROFILE IS PROGGED TO WARM RAPIDLY ALOFT AND THINK
JUST ABOUT ALL LOCATIONS IN OUR CWA WILL TURN OVER TO PLAIN OL
RAIN BY MID MORNING. FOR THE MOST PART...THE PRECIPITATION WILL BE
FALLING INTO A BOUNDARY LAYER THAT IS ABOVE FREEZING...THUS DO NOT
ANTICIPATE ANY SIGNIFICANT ACCUMULATION. THE COLDEST
LOCATIONS...ALONG AND NORTH OF INTERSTATE 64 MAY EXPERIENCE AN
INCH OR TWO OF SNOW AND SLEET...BEFORE CHANGING TO FREEZING RAIN
AND THEN RAIN. FOR THIS REASON HAVE ISSUED A WINTER WEATHER
ADVISORY THIS MORNING FOR BATH...ROCKBRIDGE...AND AMHERST. HAVE
ALSO ISSUED A FREEZING RAIN ADVISORY FOR THE NORTHWEST MOUNTAINS
OF NORTH CAROLINA...INCLUDING GRAYSON AND CARROLL COUNTIES IN
VIRGINIA WHERE TEMPERATURES ARE AROUND FREEZING.
ASIDE FROM THE INSITU COLD AIR THAT IS IN PLACE ACROSS THE
CWA...THERE IS NO BLOCKING HIGH TO THE NORTH. APPROACH OF COLD
FRONT AND WARM AIR ADVECTION AHEAD OF THIS FEATURE SHOULD ALLOW
TEMPS TO STEADILY CLIMB THROUGH THE DAY...MOST AREAS CLIMBING INTO
THE 40S.
THE SURFACE FRONT IS PROGGED TO PASS THROUGH THE AREA BY MIDNIGHT
TONIGHT WITH THE SURFACE LOW MOVING INTO EASTERN ONTARIO. STRONG
COLD AIR ADVECTION WILL TAKE PLACE BEHIND THE FRONT AND THIS WILL
SET THE STAGE FOR A COLD NEXT COUPLE OF DAYS WITH MOUNTAIN SNOW
SHOWERS AND FLURRIES ALONG WITH BRISK NORTHWEST WINDS.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
BIGGEST CONCERN FOR THIS PART OF THE PACKAGE IS WINDS AND UPSLOPE
SNOW. DEBATING WHETHER OR NOT TO ISSUE AN ELEVATION WATCH FOR
GREENBRIER. HOWEVER...NAM12 H7 MOISTURE IS FARTHER NORTH AND
MOISTURE DEPTH IS MORE SHALLOW THAN THE PAST FEW NIGHTS. SEEMS AS
THOUGH THE DEEPEST MOISTURE WILL BE AROUND FROM MID MORNING THURS
THROUGH EARLY AFTERNOON. ATTM...THE BEST COURSE OF ACTION WOULD BE
A SNOW ADVISORY SAY FROM GREENBRIER TO TAZEWELL FROM THURS INTO
THURS NIGHT BUT THIS CAN BE FINE TUNED ON FUTURE SHIFTS. ABOVE
2500 FEET IN GREENBRIER MAY BE CLOSE OR JUST ABV WARNING CRITERIA
BY FRIDAY MORNING AND THIS CAN BE HANDLED IN AN ADVISORY TOO. ANOTHER
ISSUE IS THE WIND WHICH WILL BE BLOWING THE SNOW AROUND.
NONETHELESS...IT WILL BE SNOWING HARD AT TIMES WITH WINDS GREATLY
REDUCING VISIBILITIES IN THESE SPOTS THURS AND THURS NIGHT. A
COUPLE INCHES MAY ALSO FALL IN THE SKI COUNTRY OF NW NC WITH AN
INCH OR LESS AT THE LOWER ELEVATIONS. IF WINDS STAY UP...WIND CHILL
ADVISORY CRITERIA MAY BE MET INTO FRIDAY MORNING FOR THE EXTREME
SW...WHICH WILL RECEIVE THE COLDEST AIR FIRST. CONSIDERING H85
VALUES WILL BE NEAR -15C...SHALLOW ARCTIC AIRMASS...DID KEEP TEMPS
A FEW DEGREES BELOW COLDEST GUIDANCE FOR MIN/MAX ON FRIDAY. WILL ALSO
NEED A WIND ADVISORY FOR NW NC AND POSSIBLY PART OF THE BLUE RIDGE
IN VA THURSDAY AND THURSDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
TIMING OF THE SATURDAY SYSTEM IS SIMILAR TO YESTERDAY...ALTHOUGH MAY
BE SLOWER BY A FEW HOURS. STILL LOOKING AT BEST CHANCE OF PRECIP
ARRIVING IN THE WEST DURING THE DAY AND MOVING EAST BY EVENING WITH
UPSLOPE SNOW SHOWERS ON THE BACK SIDE LASTING INTO SUNDAY.
AFTER THIS THE PATTERN FLATTENS WITH A BACKDOOR FRONT STRETCHING
INTO THE MID ATLANTIC BY TUESDAY BUT NO AFFECTS IN TERM OF PRECIP
FOR OUR AREA. TEMPS WILL SLOWLY MODERATE AS SFC HIGH SETTLES ACROSS
THE AREA SUN-MON.
THE 12Z ECMWF MODEL HAS A DIFFERENT SOLUTION INTO MONDAY AS IT FORMS
A NEW LOW ALONG THE FRONT IN THE SOUTHEAST SUNDAY MORNING AND SHIFTS
IT OFF THE NORTH CAROLINA/VIRGINIA COAST BY 12Z MONDAY. THIS SYSTEM
WOULD BRING A GOOD SNOW TO PORTIONS OF THE AREA IF IT PANS OUT...BUT
ATTM...THE OTHER MODELS ARE NOT FAVORING IT.
&&
.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
RADAR RETURNS NOT PRODUCING MUCH AT THE GROUND THIS HOUR...AND
WILL PROBABLY BE THE CASE OVER THE NEXT FEW HOURS WITH VERY DRY
LLVLS. WOULD THINK THOUGH THERE IS A GOOD CHANCE FOR ICING ALOFT
OF AIRCRAFT HOWEVER WITH THIS SETUP. VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING AS HIGH PRESSURE MAINTAINS CONTROL OF OUR
AREA. OVERNIGHT...A SYSTEM WILL SWEEP THROUGH THE AREA BRINGING
MVFR/IFR CIGS AND MAINLY MVFR VSBYS STARTING BETWEEN 08-12Z FROM
WEST TO EAST. ACCOMPANYING THIS CLOUD COVER WILL BE A BRIEF SHOT
OF SNOW/SLEET/FZRA BEFORE QUICKLY CHANGING OVER TO ALL RAIN. THE
WINTRY MIX WILL LAST LONGEST AT LWB...AND SHORTEST AT BLF. AREAS
OF SOUTHEAST WEST VIRGINIA AND PARTS OF SOUTHWEST VIRGINIA ALONG
AND NORTH OF A KROA-KLYH LINE CAN EXPECT SNOW OR SLEET AT THE
ONSET OF THE PRECIPITATION FOR A FEW HOURS. ELSEWHERE...RAIN IS
EXPECTED AT THE ONSET OF THE PRECIPITATION. DURING THE MORNING
WEDNESDAY...WARMER AIR ENTERING THE REGION WILL ALLOW FOR A
TRANISTION TO ALL RAIN ACROSS THE AREA.
THE CIG/VSBY RESTRICTIONS WILL LIKELY CONTINUE THROUGH WEDNESDAY
NIGHT UNTIL A COLD FRONT MOVES THROUGH BY THURSDAY MORNING. SCT
RAIN AND SNOW SHOWERS WILL CONTINUE IN THE WESTERN MOUNTAINS IN A
COLD NORTHWEST FLOW THURSDAY AND FRIDAY. STRONG WINDS CAN BE
EXPECTED THURSDAY/THURSDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR VAZ015-016.
WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR VAZ020-024-
035.
NC...FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NCZ001-002-018.
WV...NONE.
&&
$$
SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...KM
LONG TERM...WP
AVIATION...KM/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
357 AM EST WED FEB 18 2009
.SYNOPSIS...
A WINTER STORM WILL MOVE THROUGH THE GREAT LAKES AND OHIO VALLEY
TODAY. ITS ASSOCIATED COLD FRONT WILL MOVE EAST ACROSS THE MID
ATLANTIC REGION...SPREADING RAIN AND A BRIEF PERIOD OF WINTRY
MIX TO THE MID ATLANTIC REGION. THE COLD FRONT WILL MOVE EAST
OF THE AREA TONIGHT AS THE WINTER STORM MOVE INTO NEW ENGLAND.
COLDER AND WINDY CONDITIONS WILL DEVELOP BEHIND THE FRONT WITH
MOUNTAIN SNOW SHOWERS.
&&
.NEAR TERM /THROUGH TONIGHT/...
REGIONAL RADARS INDICATE A LARGE SWATH OF PRECIPITATION ADVANCING
EAST ACROSS TN/KY. THIS PRECIPITATION WILL ARRIVE THIS MORNING AND
WILL BE WIDESPREAD FOR AT LEAST THE FIRST HALF OF THE DAY. AT THE
ONSET...TEMPERATURES WILL SUPPORT A WINTRY MIX WITH SNOW AND
SLEET. THE PROFILE IS PROGGED TO WARM RAPIDLY ALOFT AND THINK
JUST ABOUT ALL LOCATIONS IN OUR CWA WILL TURN OVER TO PLAIN OL
RAIN BY MID MORNING. FOR THE MOST PART...THE PRECIPITATION WILL BE
FALLING INTO A BOUNDARY LAYER THAT IS ABOVE FREEZING...THUS DO NOT
ANTICIPATE ANY SIGNIFICANT ACCUMULATION. THE COLDEST
LOCATIONS...ALONG AND NORTH OF INTERSTATE 64 MAY EXPERIENCE AN
INCH OR TWO OF SNOW AND SLEET...BEFORE CHANGING TO FREEZING RAIN
AND THEN RAIN. FOR THIS REASON HAVE ISSUED A WINTER WEATHER
ADVISORY THIS MORNING FOR BATH...ROCKBRIDGE...AND AMHERST.
ASIDE FROM THE INSITU COLD AIR THAT IS IN PLACE ACROSS THE
CWA...THERE IS NO BLOCKING HIGH TO THE NORTH. APPROACH OF COLD
FRONT AND WARM AIR ADVECTION AHEAD OF THIS FEATURE SHOULD ALLOW
TEMPS TO STEADILY CLIMB THROUGH THE DAY...MOST AREAS CLIMBING INTO
THE 40S.
THE SURFACE FRONT IS PROGGED TO PASS THROUGH THE AREA BY MIDNIGHT
TONIGHT WITH THE SURFACE LOW MOVING INTO EASTERN ONTARIO. STRONG
COLD AIR ADVECTION WILL TAKE PLACE BEHIND THE FRONT AND THIS WILL
SET THE STAGE FOR A COLD NEXT COUPLE OF DAYS WITH MOUNTAIN SNOW
SHOWERS AND FLURRIES ALONG WITH BRISK NORTHWEST WINDS.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
BIGGEST CONCERN FOR THIS PART OF THE PACKAGE IS WINDS AND UPSLOPE
SNOW. DEBATING WHETHER OR NOT TO ISSUE AN ELEVATION WATCH FOR
GREENBRIER. HOWEVER...NAM12 H7 MOISTURE IS FARTHER NORTH AND
MOISTURE DEPTH IS MORE SHALLOW THAN THE PAST FEW NIGHTS. SEEMS AS
THOUGH THE DEEPEST MOISTURE WILL BE AROUND FROM MID MORNING THURS
THROUGH EARLY AFTERNOON. ATTM...THE BEST COURSE OF ACTION WOULD BE
A SNOW ADVISORY SAY FROM GREENBRIER TO TAZEWELL FROM THURS INTO
THURS NIGHT BUT THIS CAN BE FINE TUNED ON FUTURE SHIFTS. ABOVE
2500 FEET IN GREENBRIER MAY BE CLOSE OR JUST ABV WARNING CRITERIA
BY FRIDAY MORNING AND THIS CAN BE HANDLED IN AN ADVISORY TOO. ANOTHER
ISSUE IS THE WIND WHICH WILL BE BLOWING THE SNOW AROUND.
NONETHELESS...IT WILL BE SNOWING HARD AT TIMES WITH WINDS GREATLY
REDUCING VISIBILITIES IN THESE SPOTS THURS AND THURS NIGHT. A
COUPLE INCHES MAY ALSO FALL IN THE SKI COUNTRY OF NW NC WITH AN
INCH OR LESS AT THE LOWER ELEVATIONS. IF WINDS STAY UP...WIND CHILL
ADVISORY CRITERIA MAY BE MET INTO FRIDAY MORNING FOR THE EXTREME
SW...WHICH WILL RECEIVE THE COLDEST AIR FIRST. CONSIDERING H85
VALUES WILL BE NEAR -15C...SHALLOW ARCTIC AIRMASS...DID KEEP TEMPS
A FEW DEGREES BELOW COLDEST GUIDANCE FOR MIN/MAX ON FRIDAY. WILL ALSO
NEED A WIND ADVISORY FOR NW NC AND POSSIBLY PART OF THE BLUE RIDGE
IN VA THURSDAY AND THURSDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
TIMING OF THE SATURDAY SYSTEM IS SIMILAR TO YESTERDAY...ALTHOUGH MAY
BE SLOWER BY A FEW HOURS. STILL LOOKING AT BEST CHANCE OF PRECIP
ARRIVING IN THE WEST DURING THE DAY AND MOVING EAST BY EVENING WITH
UPSLOPE SNOW SHOWERS ON THE BACK SIDE LASTING INTO SUNDAY.
AFTER THIS THE PATTERN FLATTENS WITH A BACKDOOR FRONT STRETCHING
INTO THE MID ATLANTIC BY TUESDAY BUT NO AFFECTS IN TERM OF PRECIP
FOR OUR AREA. TEMPS WILL SLOWLY MODERATE AS SFC HIGH SETTLES ACROSS
THE AREA SUN-MON.
THE 12Z ECMWF MODEL HAS A DIFFERENT SOLUTION INTO MONDAY AS IT FORMS
A NEW LOW ALONG THE FRONT IN THE SOUTHEAST SUNDAY MORNING AND SHIFTS
IT OFF THE NORTH CAROLINA/VIRGINIA COAST BY 12Z MONDAY. THIS SYSTEM
WOULD BRING A GOOD SNOW TO PORTIONS OF THE AREA IF IT PANS OUT...BUT
ATTM...THE OTHER MODELS ARE NOT FAVORING IT.
&&
.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
RADAR RETURNS NOT PRODUCING MUCH AT THE GROUND THIS HOUR...AND
WILL PROBABLY BE THE CASE OVER THE NEXT FEW HOURS WITH VERY DRY
LLVLS. WOULD THINK THOUGH THERE IS A GOOD CHANCE FOR ICING ALOFT
OF AIRCRAFT HOWEVER WITH THIS SETUP. VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING AS HIGH PRESSURE MAINTAINS CONTROL OF OUR
AREA. OVERNIGHT...A SYSTEM WILL SWEEP THROUGH THE AREA BRINGING
MVFR/IFR CIGS AND MAINLY MVFR VSBYS STARTING BETWEEN 08-12Z FROM
WEST TO EAST. ACCOMPANYING THIS CLOUD COVER WILL BE A BRIEF SHOT
OF SNOW/SLEET/FZRA BEFORE QUICKLY CHANGING OVER TO ALL RAIN. THE
WINTRY MIX WILL LAST LONGEST AT LWB...AND SHORTEST AT BLF. AREAS
OF SOUTHEAST WEST VIRGINIA AND PARTS OF SOUTHWEST VIRGINIA ALONG
AND NORTH OF A KROA-KLYH LINE CAN EXPECT SNOW OR SLEET AT THE
ONSET OF THE PRECIPITATION FOR A FEW HOURS. ELSEWHERE...RAIN IS
EXPECTED AT THE ONSET OF THE PRECIPITATION. DURING THE MORNING
WEDNESDAY...WARMER AIR ENTERING THE REGION WILL ALLOW FOR A
TRANISTION TO ALL RAIN ACROSS THE AREA.
THE CIG/VSBY RESTRICTIONS WILL LIKELY CONTINUE THROUGH WEDNESDAY
NIGHT UNTIL A COLD FRONT MOVES THROUGH BY THURSDAY MORNING. SCT
RAIN AND SNOW SHOWERS WILL CONTINUE IN THE WESTERN MOUNTAINS IN A
COLD NORTHWEST FLOW THURSDAY AND FRIDAY. STRONG WINDS CAN BE
EXPECTED THURSDAY/THURSDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR VAZ020-024-
035.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...PM
NEAR TERM...PM
SHORT TERM...KM
LONG TERM...WP
AVIATION...KM/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
337 AM EST WED FEB 18 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL MOVE OFF THE COAST OVERNIGHT.
MORE WINTRY PRECIPITATION IS EXPECTED LATE TONIGHT AND WEDNESDAY
AHEAD OF A COLD FRONT THAT WILL MOVE THROUGH THE REGION WEDNESDAY
NIGHT. COLD AND WINDY CONDITIONS ALONG WITH SNOW SHOWERS WILL
PERSIST INTO THE LATTER PART OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
UPSTREAM RADAR CONTINUES TO SHOW PRECIP MOVG INTO THE MTNS IN
BANDED WAVES. NOT REAL GOOD COVERAGE...BUT ENOUGH FOR LIKELY POPS
IN THE SW MTNS OF VA AND THE NRN MTNS OF NC LATE THIS EVENING. I
HAVE ALSO PUSHED THE CHC POPS FURTHER EAST LATE THIS
EVENING...THOUGH IT IS QUESTIONABLE THAT MEASURABLE PRECIP WILL
REACH THE GROUND DESPITE RETURNS ON RADAR. HAVE KEPT THE
CATEGORICAL/HIGH LIKELY POPS AFTER 09Z THAT WE HAD GOING. THINK BY
THEN THE ATMOSPHERE WILL BE NEARLY SATURATED...AND ISENTROPIC LIFT
CONTINUES INTO THE AREA. MAIN QUESTION IS P-TYPE AND WHEN IT
CHANGES...AS THE WARM ADVECTION CONTINUES AS WELL. THE 00Z RNK
SOUNDING HAS A WET BULB ENTIRELY BELOW ZERO...BUT THE COLUMN WILL
BE WARMING FROM THE TOP DOWN CHANGING THE PRECIP FROM WHAT WILL
LIKELY BE A SNOW/SLEET START INTO LIQUID AFTER JUST A FEW HOURS
MOST LOCATIONS. WITHOUT A SFC HIGH PRESSURE TO HOLD A STRONG WEDGE
IN PLACE...THE PATTERN DOES NOT LOOK FAVORABLE FOR THE SFC TO
REMAIN COLD FOR MUCH FREEZING RAIN EITHER. BEST CHC FOR MUCH
ACCUMULATION LOOKS TO BE IN THE NE- GREENBRIER...BATH...
ROCKBRIDGE AND AMHERST COUNTIES. HOWEVER...WITH WHAT IS LIKELY TO
BE A SNOW/SLEET MIX...WILL BE TOUGH TO GET MUCH MORE THAN AN INCH.
I HAVE LOWERED WON ACCUM AMOUNTS THROUGH 12Z...THEN LEFT THE LIGHT
AMOUNTS THAT WE HAD GOING IN THE NE BETWEEN 12 AND 15Z. FCST LOWS
LOOKED ON TRACK...UPPER 20S TO MID 30S...WITH MINOR ADJUSTMENTS.
THERE IS STILL SOME POTENTIAL FOR SNOW/SLEET ON THE ROADS RIGHT AT
THE TIME OF THE MORNING COMMUTE...SO WILL KEEP A MENTION IN THE
HAZARDOUS WEATHER OUTLOOK WHERE WE HAVE ANY SNOW OR SLEET IN THE
FCST.
&&
.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
BIGGEST CONCERN FOR THIS PART OF THE PACKAGE IS WINDS AND UPSLOPE
SNOW. DEBATING WHETHER OR NOT TO ISSUE AN ELEVATION WATCH FOR
GREENBRIER. HOWEVER...NAM12 H7 MOISTURE IS FARTHER NORTH AND
MOISTURE DEPTH IS MORE SHALLOW THAN THE PAST FEW NIGHTS. SEEMS AS
THOUGH THE DEEPEST MOISTURE WILL BE AROUND FROM MID MORNING THURS
THROUGH EARLY AFTERNOON. ATTM...THE BEST COURSE OF ACTION WOULD BE
A SNOW ADVISORY SAY FROM GREENBRIER TO TAZEWELL FROM THURS INTO
THURS NIGHT BUT THIS CAN BE FINE TUNED ON FUTURE SHIFTS. ABOVE
2500 FEET IN GREENBRIER MAY BE CLOSE OR JUST ABV WARNING CRITERIA
BY FRIDAY MORNING AND THIS CAN BE HANDLED IN AN ADVISORY TOO. ANOTHER
ISSUE IS THE WIND WHICH WILL BE BLOWING THE SNOW AROUND.
NONETHELESS...IT WILL BE SNOWING HARD AT TIMES WITH WINDS GREATLY
REDUCING VISIBILITIES IN THESE SPOTS THURS AND THURS NIGHT. A
COUPLE INCHES MAY ALSO FALL IN THE SKI COUNTRY OF NW NC WITH AN
INCH OR LESS AT THE LOWER ELEVATIONS. IF WINDS STAY UP...WIND CHILL
ADVISORY CRITERIA MAY BE MET INTO FRIDAY MORNING FOR THE EXTREME
SW...WHICH WILL RECEIVE THE COLDEST AIR FIRST. CONSIDERING H85
VALUES WILL BE NEAR -15C...SHALLOW ARCTIC AIRMASS...DID KEEP TEMPS
A FEW DEGREES BELOW COLDEST GUIDANCE FOR MIN/MAX ON FRIDAY. WILL ALSO
NEED A WIND ADVISORY FOR NW NC AND POSSIBLY PART OF THE BLUE RIDGE
IN VA THURSDAY AND THURSDAY NIGHT.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
TIMING OF THE SATURDAY SYSTEM IS SIMILAR TO YESTERDAY...ALTHOUGH MAY
BE SLOWER BY A FEW HOURS. STILL LOOKING AT BEST CHANCE OF PRECIP
ARRIVING IN THE WEST DURING THE DAY AND MOVING EAST BY EVENING WITH
UPSLOPE SNOW SHOWERS ON THE BACK SIDE LASTING INTO SUNDAY.
AFTER THIS THE PATTERN FLATTENS WITH A BACKDOOR FRONT STRETCHING
INTO THE MID ATLANTIC BY TUESDAY BUT NO AFFECTS IN TERM OF PRECIP
FOR OUR AREA. TEMPS WILL SLOWLY MODERATE AS SFC HIGH SETTLES ACROSS
THE AREA SUN-MON.
THE 12Z ECMWF MODEL HAS A DIFFERENT SOLUTION INTO MONDAY AS IT FORMS
A NEW LOW ALONG THE FRONT IN THE SOUTHEAST SUNDAY MORNING AND SHIFTS
IT OFF THE NORTH CAROLINA/VIRGINIA COAST BY 12Z MONDAY. THIS SYSTEM
WOULD BRING A GOOD SNOW TO PORTIONS OF THE AREA IF IT PANS OUT...BUT
ATTM...THE OTHER MODELS ARE NOT FAVORING IT.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
RADAR RETURNS NOT PRODUCING MUCH AT THE GROUND THIS HOUR...AND
WILL PROBABLY BE THE CASE OVER THE NEXT FEW HOURS WITH VERY DRY
LLVLS. WOULD THINK THOUGH THERE IS A GOOD CHANCE FOR ICING ALOFT
OF AIRCRAFT HOWEVER WITH THIS SETUP. VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING AS HIGH PRESSURE MAINTAINS CONTROL OF OUR
AREA. OVERNIGHT...A SYSTEM WILL SWEEP THROUGH THE AREA BRINGING
MVFR/IFR CIGS AND MAINLY MVFR VSBYS STARTING BETWEEN 08-12Z FROM
WEST TO EAST. ACCOMPANYING THIS CLOUD COVER WILL BE A BRIEF SHOT
OF SNOW/SLEET/FZRA BEFORE QUICKLY CHANGING OVER TO ALL RAIN. THE
WINTRY MIX WILL LAST LONGEST AT LWB...AND SHORTEST AT BLF. AREAS
OF SOUTHEAST WEST VIRGINIA AND PARTS OF SOUTHWEST VIRGINIA ALONG
AND NORTH OF A KROA-KLYH LINE CAN EXPECT SNOW OR SLEET AT THE
ONSET OF THE PRECIPITATION FOR A FEW HOURS. ELSEWHERE...RAIN IS
EXPECTED AT THE ONSET OF THE PRECIPITATION. DURING THE MORNING
WEDNESDAY...WARMER AIR ENTERING THE REGION WILL ALLOW FOR A
TRANISTION TO ALL RAIN ACROSS THE AREA.
THE CIG/VSBY RESTRICTIONS WILL LIKELY CONTINUE THROUGH WEDNESDAY
NIGHT UNTIL A COLD FRONT MOVES THROUGH BY THURSDAY MORNING. SCT
RAIN AND SNOW SHOWERS WILL CONTINUE IN THE WESTERN MOUNTAINS IN A
COLD NORTHWEST FLOW THURSDAY AND FRIDAY. STRONG WINDS CAN BE
EXPECTED THURSDAY/THURSDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS/JJ
SHORT TERM...KM
LONG TERM...WP
AVIATION...KM/WP
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1157 PM EST TUE FEB 17 2009
.SYNOPSIS...
HIGH PRESSURE OVER THE REGION WILL MOVE OFF THE COAST OVERNIGHT.
MORE WINTRY PRECIPITATION IS EXPECTED LATE TONIGHT AND WEDNESDAY
AHEAD OF A COLD FRONT THAT WILL MOVE THROUGH THE REGION WEDNESDAY
NIGHT. COLD AND WINDY CONDITIONS ALONG WITH SNOW SHOWERS WILL
PERSIST INTO THE LATTER PART OF THE WEEK.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
UPSTREAM RADAR CONTINUES TO SHOW PRECIP MOVG INTO THE MTNS IN
BANDED WAVES. NOT REAL GOOD COVERAGE...BUT ENOUGH FOR LIKELY POPS
IN THE SW MTNS OF VA AND THE NRN MTNS OF NC LATE THIS EVENING. I
HAVE ALSO PUSHED THE CHC POPS FURTHER EAST LATE THIS
EVENING...THOUGH IT IS QUESTIONABLE THAT MEASURABLE PRECIP WILL
REACH THE GROUND DESPITE RETURNS ON RADAR. HAVE KEPT THE
CATEGORICAL/HIGH LIKELY POPS AFTER 09Z THAT WE HAD GOING. THINK BY
THEN THE ATMOSPHERE WILL BE NEARLY SATURATED...AND ISENTROPIC LIFT
CONTINUES INTO THE AREA. MAIN QUESTION IS P-TYPE AND WHEN IT
CHANGES...AS THE WARM ADVECTION CONTINUES AS WELL. THE 00Z RNK
SOUNDING HAS A WET BULB ENTIRELY BELOW ZERO...BUT THE COLUMN WILL
BE WARMING FROM THE TOP DOWN CHANGING THE PRECIP FROM WHAT WILL
LIKELY BE A SNOW/SLEET START INTO LIQUID AFTER JUST A FEW HOURS
MOST LOCATIONS. WITHOUT A SFC HIGH PRESSURE TO HOLD A STRONG WEDGE
IN PLACE...THE PATTERN DOES NOT LOOK FAVORABLE FOR THE SFC TO
REMAIN COLD FOR MUCH FREEZING RAIN EITHER. BEST CHC FOR MUCH
ACCUMULATION LOOKS TO BE IN THE NE- GREENBRIER...BATH...
ROCKBRIDGE AND AMHERST COUNTIES. HOWEVER...WITH WHAT IS LIKELY TO
BE A SNOW/SLEET MIX...WILL BE TOUGH TO GET MUCH MORE THAN AN INCH.
I HAVE LOWERED WON ACCUM AMOUNTS THROUGH 12Z...THEN LEFT THE LIGHT
AMOUNTS THAT WE HAD GOING IN THE NE BETWEEN 12 AND 15Z. FCST LOWS
LOOKED ON TRACK...UPPER 20S TO MID 30S...WITH MINOR ADJUSTMENTS.
THERE IS STILL SOME POTENTIAL FOR SNOW/SLEET ON THE ROADS RIGHT AT
THE TIME OF THE MORNING COMMUTE...SO WILL KEEP A MENTION IN THE
HAZARDOUS WEATHER OUTLOOK WHERE WE HAVE ANY SNOW OR SLEET IN THE
FCST.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
WEDNESDAY NIGHT...THEN FRONT WILL BE PUSHING ACROSS THE AREA AND BE
NEAR THE BLUE RIDGE AROUND 06Z THU. AROUND 12Z THU...THE FRONT WILL
BE WELL EAST OF THE AREA...BUT THE DEW POINT FRONT AND STRONGER COLD
AIR WILL BE DELAYED A BIT. WITH THE LOW BECOMING OCCLUDED OVER LAKE
ERIE...RAIN SHOWERS WILL PERSIST DURING THE EVENING BUT DECREASE IN
COVERAGE. AFTER 06Z THU...SOME LIGHT RAIN/DRIZZLE MAY LINGER ACROSS
THE MOUNTAINS WITH HIGHER ELEVATIONS TRANSITIONING OVER TO SNOW.
THURSDAY AFTERNOON...THIS LOW PRESSURE SYSTEM WILL BE MOVING EAST
ACROSS PA. WRAP-A-ROUND MOISTURE AND A WESTERLY FLOW WILL BRING
ACCUMULATING SNOW TO WESTERN SLOPES THROUGH FRIDAY. THE DIRECTION OF
THE WINDS WILL BE MORE WESTERLY WITH A BRIEF CONNECTION TO THE GREAT
LAKES THURSDAY AFTERNOON AND EVENING. AREAS EAST OF THESE SE WV/SW
VA/NW NC WESTERN RIDGES WILL SEE VERY LITTLE ACCUMULATION. AFTER 06Z
FRI...BULK OF MOISTURE PULLS TO THE NORTH AND BY SUNRISE
FRIDAY...SNOW SHOWERS WILL BE PRIMARILY IN SE WV AND NORTH. BY
FRIDAY NIGHT...ALL SNOW SHOWERS WILL HAVE EXITED THE AREA.
ELEVATION/ASPECT DEPENDANT ADVISORIES/WARNING MAY NEED TO BE ISSUED FOR
THIS EVENT. WE STILL HAVE ANOTHER 24 HOURS TO LOOK AT THIS EVENT BUT
WILL ONLY HIGHLIGHT IT IN THE HAZARDOUS WEATHER OUTLOOK FOR NOW.
FOLLOWING THE FRONTAL PASSAGE THURSDAY MORNING...WINTER WILL MAKE A
RETURN AND TEMPERATURES WILL LIKELY REMAIN BELOW NORMAL INTO THE
WEEKEND. TEMPERATURES THURSDAY WILL NOT WARM MUCH ACROSS THE
MOUNTAINS WITH MORNING HIGHS IN THE 30S. EAST OF THE BLUE
RIDGE...DOWNSLOPING MAY ALLOW FOR A NORMAL DIURNAL CURVE BUT
WINDY/GUSTY CONDITIONS WILL MAKE IT FEEL COLDER DURING THE
AFTERNOON. THE WIND WILL PICK UP THROUGH THE DAY THURSDAY AND REMAIN
INTO FRIDAY. WINDS/GUSTS COULD REACH ADVISORY CRITERIA THURSDAY AND
THURSDAY NIGHT ALONG THE BLUE RIDGE.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
TIMING OF THE SATURDAY SYSTEM IS SIMILAR TO YESTERDAY...ALTHOUGH MAY
BE SLOWER BY A FEW HOURS. STILL LOOKING AT BEST CHANCE OF PRECIP
ARRIVING IN THE WEST DURING THE DAY AND MOVING EAST BY EVENING WITH
UPSLOPE SNOW SHOWERS ON THE BACK SIDE LASTING INTO SUNDAY.
AFTER THIS THE PATTERN FLATTENS WITH A BACKDOOR FRONT STRETCHING
INTO THE MID ATLANTIC BY TUESDAY BUT NO AFFECTS IN TERM OF PRECIP
FOR OUR AREA. TEMPS WILL SLOWLY MODERATE AS SFC HIGH SETTLES ACROSS
THE AREA SUN-MON.
THE 12Z ECMWF MODEL HAS A DIFFERENT SOLUTION INTO MONDAY AS IT FORMS
A NEW LOW ALONG THE FRONT IN THE SOUTHEAST SUNDAY MORNING AND SHIFTS
IT OFF THE NORTH CAROLINA/VIRGINIA COAST BY 12Z MONDAY. THIS SYSTEM
WOULD BRING A GOOD SNOW TO PORTIONS OF THE AREA IF IT PANS OUT...BUT
ATTM...THE OTHER MODELS ARE NOT FAVORING IT.
&&
.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
RADAR RETURNS NOT PRODUCING MUCH AT THE GROUND THIS HOUR...AND
WILL PROBABLY BE THE CASE OVER THE NEXT FEW HOURS WITH VERY DRY
LLVLS. WOULD THINK THOUGH THERE IS A GOOD CHANCE FOR ICING ALOFT
OF AIRCRAFT HOWEVER WITH THIS SETUP. VFR CONDITIONS WILL CONTINUE
THROUGH THIS EVENING AS HIGH PRESSURE MAINTAINS CONTROL OF OUR
AREA. OVERNIGHT...A SYSTEM WILL SWEEP THROUGH THE AREA BRINGING
MVFR/IFR CIGS AND MAINLY MVFR VSBYS STARTING BETWEEN 08-12Z FROM
WEST TO EAST. ACCOMPANYING THIS CLOUD COVER WILL BE A BRIEF SHOT
OF SNOW/SLEET/FZRA BEFORE QUICKLY CHANGING OVER TO ALL RAIN. THE
WINTRY MIX WILL LAST LONGEST AT LWB...AND SHORTEST AT BLF. AREAS
OF SOUTHEAST WEST VIRGINIA AND PARTS OF SOUTHWEST VIRGINIA ALONG
AND NORTH OF A KROA-KLYH LINE CAN EXPECT SNOW OR SLEET AT THE
ONSET OF THE PRECIPITATION FOR A FEW HOURS. ELSEWHERE...RAIN IS
EXPECTED AT THE ONSET OF THE PRECIPITATION. DURING THE MORNING
WEDNESDAY...WARMER AIR ENTERING THE REGION WILL ALLOW FOR A
TRANISTION TO ALL RAIN ACROSS THE AREA.
THE CIG/VSBY RESTRICTIONS WILL LIKELY CONTINUE THROUGH WEDNESDAY
NIGHT UNTIL A COLD FRONT MOVES THROUGH BY THURSDAY MORNING. SCT
RAIN AND SNOW SHOWERS WILL CONTINUE IN THE WESTERN MOUNTAINS IN A
COLD NORTHWEST FLOW THURSDAY AND FRIDAY. STRONG WINDS CAN BE
EXPECTED THURSDAY/THURSDAY NIGHT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...DS
NEAR TERM...DS/JJ
SHORT TERM...RCS
LONG TERM...WP
AVIATION...KM/WP
AREA FORECAST DISCUSSION
NWS HONOLULU HI
400 PM HST THU FEB 19 2009
.SYNOPSIS...
HIGH PRESSURE NORTH OF THE STATE WILL MAINTAIN NORTHEASTERLY TRADE
WINDS THROUGH EARLY NEXT WEEK. CLOUDS AND SHOWERS ASSOCIATED WITH A
DISSIPATING SHEAR LINE WILL AFFECT THE STATE TONIGHT...PRIMARILY
WINDWARD AND MAUKA SECTIONS. SUNNIER WEATHER AND GENTLER TRADES ARE
IN STORE FOR THE WEEKEND.
&&
.DISCUSSION...
WATER VAPOR IMAGERY SHOWS A LARGE UPPER LOW FAR NORTHEAST OF THE
STATE...WITH A WEAK TROUGH EXTENDING BACK ACROSS THE ISLANDS. AN
AMPLIFIED RIDGE IS LOCATED TO OUR NORTHWEST. ACROSS THE STATE...
VISIBLE SATELLITE SHOWS AN AREA OF SHOWERY LOW CLOUDS ASSOCIATED
WITH A DISSIPATING SHEAR LINE ACROSS WINDWARD COASTAL WATERS. THESE
CLOUDS HAVE THINNED DURING THE DAY...BUT A LARGER AREA OF OVERCAST
STRATOCUMULUS IS LOCATED ABOUT 100-150 MILES UPSTREAM TO THE
NORTHEAST. THESE CLOUDS ARE ASSOCIATED WITH A COOLER AND MORE STABLE
AIRMASS. 00Z SOUNDINGS FROM HILO AND LIHUE AND 22Z-00Z ACARS
SOUNDINGS SHOW INVERSION HEIGHTS RUNNING AROUND 6-7KFT. PRECIPITABLE
WATERS ARE AROUND 1 INCH...HIGHER NEAR THE BIG ISLAND. THE POES AMSU
TOTAL PRECIPITABLE WATER SENSOR SHOWS EVEN DRIER AIR UPSTREAM...WITH
PW/S NEAR 0.6 INCHES NORTH OF THE STATE.
THE MORNING QUIKSCAT PASS BRUSHED THE WESTERN HALF OF THE
STATE...AND SHOWED GENERAL 20-25 KNOT WINDS ACROSS MOST COASTAL
WATERS. WINDS ACROSS LAND HAVE REMAINED GUSTY DESPITE 24 HOUR
PRESSURE FALLS OF AROUND 1MB. REGIONAL RADARS SHOW LIGHT SHOWERS
AFFECTING MUCH OF THE AREA...WITH INDIVIDUAL SHOWERS SMALL AND FAST
MOVING. RAINFALL AMOUNTS HAVE BEEN LIGHT THIS AFTERNOON...WITH MOST
RAINFALL REPORTS AROUND A TENTH OF AN INCH OR LESS BUT A HANDFUL OF
SITES AROUND A QUARTER INCH. CLOUDS AND SHOWERS WILL LINGER ACROSS
THE STATE TONIGHT BEFORE STARTING TO DIMINISH ON FRIDAY. RAINFALL
WILL FAVOR WINDWARD AND MAUKA AREAS...BUT WINDS WILL CARRY THEM
ACROSS LEEWARD SECTIONS AS WELL. TEMPERATURES WILL REMAIN ON THE
COOL SIDE.
THE UPPER LEVEL RIDGE WILL BUILD ACROSS THE STATE THIS WEEKEND. THE
INCREASED SUBSIDENCE UNDER THE BUILDING HEIGHTS WILL HELP TO LOWER
THE INVERSION TO 4-5KFT BASED ON 12Z/18Z GFS FORECAST SOUNDINGS.
RAINFALL WILL BE LIMITED UNDER THE DRY AND STABLE AIRMASS...WITH
POPS BELOW CLIMATOLOGY.
EARLY NEXT WEEK THE PATTERN BEGINS TO CHANGE. A SHORTWAVE TROUGH
APPROACHES THE STATE SUNDAY NIGHT...BRINGING AN INCREASE IN MOISTURE
AND LIFTING THE INVERSION HEIGHT TO 7-8KFT. THE GFS DEVELOPS A
STRONGER SURFACE REFLECTION NORTH OF THE STATE WITH THIS FEATURE
THAN THE ECMWF DOES...AND CONSEQUENTLY WEAKENS WINDS MORE ACROSS THE
ISLANDS. THE 12Z ECMWF HAS ACTUALLY TRENDED WEAKER AS WELL...BUT
STILL MAINTAINS TRADES THROUGH THE EXTENDED PERIOD.
BY MID-WEEK...A SECOND SHORTWAVE COMES INTO PLAY...ERODING THE
INVERSION ALL TOGETHER AND DESTABILIZING THE ATMOSPHERE. AT THE SAME
TIME...A LARGE +1040MB HIGH IS EXPECTED TO BUILD FAR NORTH OF THE
STATE. THE 12Z AND 18Z GFS RUNS HAVE TRENDED AWAY FROM THE 06Z RUN
WITH RESPECT TO AN UPPER LEVEL TROUGH PASSING NORTH OF THE STATE.
THE CURRENT RUN IS SLOWER AND MORE AMPLIFIED...AND MORE IN LINE WITH
THE 00Z/12Z ECMWF RUNS. WHILE THE GFS DOES NOT SHOW MUCH OF A
REFLECTION AT THE SURFACE...MODEL WIND SPEEDS ACROSS THE ISLANDS
HAVE TRENDED WEAKER WITH THE NEW SOLUTION AS THE UPPER TROUGH
PARTIALLY ISOLATES US FROM THE STRONG BUILDING HIGH. GIVEN THE
AGREEMENT BETWEEN THE GFS AND ECMWF...HAVE SLOWED THE INCREASE IN
WIND SPEED LATE IN THE FORECAST.
&&
.MARINE...
18Z WAVEWATCH III GUIDANCE CONTINUES TO SHOW THE NEXT NORTHEAST
SWELL BUILDING TONIGHT/FRIDAY AND CONTINUING THROUGH EARLY NEXT
WEEK. WHILE COMBINED SEAS ON THE MOKAPU BUOY HAVE NOT CHANGED MUCH
DURING THE LAST FEW HOURS...IT HAS BEGUN TO SEE AN INCREASE IN
LONGER PERIOD ENERGY. WILL ISSUE A HIGH SURF ADVISORY FOR EAST
FACING SHORES OF ALL ISLANDS BEGINNING TONIGHT. AS THE PERIOD AND
SWELL HEIGHTS INCREASE...THIS NORTHEAST SWELL ALSO MAY LEAD TO
HARBOR SURGES IN KAHULUI AND HILO HARBORS.
THE INCREASING SWELL WILL COMBINED WITH THE FRESH TO STRONG TRADE
WINDS TO CREATE SMALL CRAFT CONDITIONS ACROSS ALL HAWAIIAN
WATERS...EITHER DUE TO WINDS TO 25 KNOTS OR COMBINED SEAS OF 10 FEET
OR GREATER.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
HIGH SURF ADVISORY FROM 6 PM THIS EVENING TO 6 PM HST SATURDAY FOR
EAST FACING SHORES OF ALL ISLANDS.
SMALL CRAFT ADVISORY UNTIL 6 PM HST FRIDAY FOR ALL HAWAIIAN WATERS.
&&
$$
BRAVENDER
AREA FORECAST DISCUSSION
NWS HONOLULU HI
1000 AM HST THU FEB 19 2009
.SYNOPSIS...
HIGH PRESSURE NORTH OF THE STATE WILL MAINTAIN NORTHEASTERLY TRADE
WINDS THROUGH EARLY NEXT WEEK. A SHEAR LINE NEAR THE BIG ISLAND WILL
DISSIPATE TODAY. NORTH OF THE SHEAR LINE...A LARGE AREA OF STABLE
LOW CLOUDS IS MOVING SOUTHWARD ACROSS THE STATE. SUNNIER WEATHER AND
GENTLER TRADES ARE ON TAP FOR THE WEEKEND.
&&
.DISCUSSION...
WATER VAPOR IMAGERY SHOWS A LARGE UPPER LOW FAR NORTHEAST OF THE
STATE...WITH A WEAK TROUGH EXTENDING BACK ACROSS THE ISLANDS. AN
AMPLIFIED RIDGE IS LOCATED TO OUR NORTHWEST. ACROSS THE STATE...
VISIBLE SATELLITE SHOWS AN AREA OF SHOWERY LOW CLOUDS...ASSOCIATED
WITH A DISSIPATING SHEAR LINE...AFFECTING WINDWARD BIG ISLAND.
ANOTHER AREA OF CLOUDS IS APPROACHING THE SMALLER ISLANDS. THESE
CLOUDS ARE ASSOCIATED WITH A COOLER AND MORE STABLE AIRMASS. 12Z
SOUNDINGS FROM HILO AND LIHUE AND 17Z-18Z ACARS SOUNDINGS OUT OF
HONOLULU AND KONA SHOW INVERSIONS RUNNING FROM 5-7KFT. PRECIPITABLE
WATERS RANGE FROM 1 INCH AT HILO TO 3/4 OF AN INCH AT LIHUE. THE
POES AMSU TOTAL PRECIPITABLE WATER SENSOR SHOWS EVEN DRIER AIR
UPSTREAM...WITH PW/S NEAR 0.6 INCHES NORTH OF THE STATE.
WITH THE INCOMING MOISTURE TO THE NORTH OF THE STATE...CLOUDS AND
SHOWERS WILL LINGER THROUGH THE AFTERNOON. MOST SHOWERS WILL AFFECT
WINDWARD SLOPES...BUT THE WINDS WILL CARRY THEM ACROSS LEEWARD
SECTIONS AS WELL. WILL SEND OUT AN UPDATE TO CARRY MORE SHOWERS
THROUGH THE AFTERNOON. TEMPERATURES WILL BE ON THE COOL SIDE...WHICH
IS ALREADY REFLECTED IN THE GOING FORECAST.
THE MORNING QUIKSCAT PASS BRUSHED THE WESTERN HALF OF THE
STATE...AND SHOWED GENERAL 20-25KTS ACROSS MOST COASTAL WATERS.
WINDS ACROSS LAND REMAIN GUSTY DESPITE 24 HOUR PRESSURE FALLS OF
1-1.5MB. TEMPERATURES WILL BE ON THE COOL SIDE...A FEELING WHICH
WILL BE FURTHER ENHANCED BY THE WINDS AND ANY PASSING SHOWERS.
THE UPPER LEVEL RIDGE WILL BUILD ACROSS THE STATE THIS WEEKEND. THE
INCREASED SUBSIDENCE UNDER THE BUILDING HEIGHTS WILL HELP TO LOWER
THE INVERSION TO 4-5KFT BASED ON 12Z GFS FORECAST SOUNDINGS.
RAINFALL WILL BE LIMITED UNDER THE DRY AND STABLE AIRMASS...WITH
POPS BELOW CLIMATOLOGY.
EARLY NEXT WEEK THE PATTERN BEGINS TO CHANGE. A SHORTWAVE TROUGH
APPROACHES THE STATE SUNDAY NIGHT...BRINGING AN INCREASE IN MOISTURE
AND LIFTING THE INVERSION HEIGHT TO 7-8KFT. THE GFS DEVELOPS A
STRONGER SURFACE REFLECTION NORTH OF THE STATE WITH THIS FEATURE
THAN THE ECMWF DOES...AND CONSEQUENTLY WEAKENS WINDS MORE ACROSS THE
ISLANDS. THE ECMWF HAS ACTUALLY BE TRENDED WEAKER AS WELL...BUT
STILL MAINTAINS TRADES THROUGH THE EXTENDED PERIOD.
BY MID-WEEK...A SECOND SHORTWAVE COMES INTO PLAY...ERODING THE
INVERSION ALL TOGETHER AND DESTABILIZING THE ATMOSPHERE. AT THE SAME
TIME...A LARGE +1040MB HIGH IS EXPECTED TO BUILD FAR NORTH OF THE
STATE. THE 12Z GFS TRENDED AWAY FROM THE 06Z RUN WITH RESPECT TO AN
UPPER LEVEL TROUGH PASSING NORTH OF THE STATE. THE CURRENT RUN IS
SLOWER AND MORE AMPLIFIED...AND MORE IN LINE WITH THE 00Z/12Z ECMWF
RUNS. WHILE THE GFS DOES NOT SHOW MUCH OF A REFLECTION AT THE
SURFACE...MODEL WIND SPEEDS ACROSS THE ISLANDS HAVE TRENDED WEAKER
WITH THE NEW SOLUTION AS THE UPPER TROUGH PARTIALLY ISOLATES US FROM
THE STRONG BUILDING HIGH.
&&
.MARINE...
SMALL CRAFT ADVISORIES REMAIN IN EFFECT FOR MOST HAWAIIAN WATERS
FOR A COMBINATION OF WINDS OF 25 KNOTS AND SEAS OF 10 FEET OR
GREATER. THE EXCEPTION IS ACROSS BIG ISLAND WINDWARD WATERS...BUT
THE ADVISORY WILL LIKELY BE EXPANDED THERE THIS AFTERNOON DUE TO THE
BUILDING NORTHEAST SWELL. 12Z WAVEWATCH III GUIDANCE SHOWS THE SWELL
BUILDING TONIGHT/FRIDAY. WILL LIKELY ALSO ISSUE A HIGH SURF ADVISORY
FOR EAST FACING SHORES. THIS NORTHEAST SWELL ALSO MAY LEAD TO HARBOR
SURGES IN KAHULUI AND HILO HARBORS.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
SMALL CRAFT ADVISORY FOR ALL HAWAIIAN WATERS EXCEPT WINDWARD BIG
ISLAND UNTIL 6 PM FRIDAY.
&&
$$
BRAVENDER
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