334
FXUS61 KRLX 090851
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
351 AM EST MON NOV 9 2009
SYNOPSIS
HIGH PRESSURE REMAINS IN CONTROL AS HIGH CLOUDS INCREASES. HAZE
AND/OR POLLUTION BUILD UP TODAY IN THE STABLE AIR. MOISTURE
INCREASES TUESDAY FROM LOW PRESSURE TO THE SOUTH.
NEAR TERM /THROUGH TONIGHT/
A 15 TO 20 DEG F INVERSION IN THE LOWER 2 THSD FT AT 08Z. HAVE HIGH
CLOUDS INCREASING FROM SW TO NE THIS MORNING. AS WE HAVE BEEN
MENTIONING OF LATE...THE CIRRUS THIS TIME OF THE YEAR...MAKES US
LEERY OF GOING TOO WARM FOR MAXIMUM TEMPERATURE. SO HAVE THE MAXIMUM
TEMPERATURE UNDER YESTERDAYS VALUES IN MOST OF THE LOWLANDS...THE
EXCEPTION MAY BE ELEVATIONS AOA 2 THSD FT.
WITH THE CONTINUATION OF THE DRY AND WARM CONDITIONS...YOU MAY FIRST
THINK OUR MAIN CONCERN TODAY WAS FIRE WEATHER. HOWEVER...WITH A
STABLE ATMOSPHERE THROUGH ABOUT 8 THSD FT MSL...MY MAIN CONCERN WAS
THE POOR VENTILATION TODAY DUE TO THE LOW MIXING HEIGHTS AND WEAK
TRANSPORT WINDS. WE HAVE THE MIXING HEIGHTS STRUGGLING TO GET AOA
1500 FEET AGL IN THE AFTERNOON. SO HAZE AND OR POLLUTION COULD
EASILY BUILD UP IN THE BOUNDARY LAYER...ESPECIALLY ALONG URBAN RIVER
VALLEYS. WILL MENTION THIS IN THE IMPACTS FOR TODAY. THUS THE
REASON FOR THE HAZE TODAY IN OUR HOURLY WEATHER GRAPHICS.
ON THE DIURNAL TEMPERATURE TRACE TODAY...SPENT TIME TRYING TO HAVE A
BIGGER THAN USUAL INCREASE BETWEEN 12 AND 15Z. DUE TO THE
ISOTHERMAL STABLE NATURE OF THE SOUNDING THIS AFTERNOON...OUR HIGH
TERRAIN COULD BE JUST AS WARM AS SOME THE WESTERN VALLEYS.
MORE OF THE SAME TONIGHT...TRYING TO FIGURE OUT THE MINIMUM
TEMPERATURE IS DIFFICULT WITH HIGH/MID CLOUDS AND SOME VALLEYS
DECOUPLING.
NO CHANGES ON OUR POPS WITH CHANCE POPS REACHING INTO SW VA BY 12Z.
SHORT TERM /TUESDAY THROUGH THURSDAY/
STILL A VARIETY OF MODEL SOLUTIONS REGARDING EVENTUAL FATE OF
APPROACHING WEAK COLD FRONT...PLUS REMNANT MOISTURE FROM IDA. THE
GFS IS THE STRONG OUTLIER...PHASING THE STREAMS ALONG THE ATLANTIC
COAST AND CREATING A STRONG CLOSED H500 LOW OVER THE APPALACHIANS BY
WEDNESDAY AFTERNOON. THE NAM WANTS TO SUPPRESS ALL OF THE TROPICAL
MOISTURE TO THE SOUTH...AND INSTEAD BRING ACROSS A WEAK MIDLEVEL
WAVE ASSOCIATED WITH THE COLD FRONT...AND WITH VIRTUALLY NO
PRECIPITATION. THE UKMET/GEM ALSO HAVE DIFFERING VIEWS. THE ECMWF
OFFERS MORE OF A COMPROMISE...WITH PHASING OCCURRING OFFSHORE OF THE
SOUTHEAST U.S...WHILE SKIMMING THE CWA WITH THE IDA REMNANT
MOISTURE. WENT WITH THIS SOLUTION...WHICH PRESERVE SOME MEASURE OF
CONTINUITY. STILL HAVE A DECENT GRADIENT IN THE POP GRIDS...RANGING
FROM LIKELY IN THE FAR SOUTH AND EAST TO LOW CHANCE IN THE
NORTHWEST. IN FACT...SOUTHEAST OHIO MAY WELL END UP GETTING ZERO
RAINFALL FROM THE STRUNG-OUT FRONT WHICH SINKS IN DURING THE DAY
TUESDAY. BULK OF THE TROPICAL MOISTURE ARRIVES AFTER 18Z TUESDAY IN
THE SOUTH AND EAST. ONE QUARTER TO ONE HALF INCH OF RAIN MAY FALL
IN SOUTHWEST VIRGINIA AND SOUTHEAST WEST VIRGINIA THROUGH 12Z
WEDNESDAY...WITH AMOUNTS DROPPING OFF TO THE NORTHWEST FAIRLY
QUICKLY.
BY SUNRISE WEDNESDAY...MOST OF THE MOISTURE HAS PULLED OFF TO THE
EAST. SOME LIGHT RAIN MAY LINGER IN THE MOUNTAINS DURING THE
MORNING...BUT NORTHEAST FLOW AROUND THE LOW TO THE SOUTHEAST MEANS
NO BACKSIDE UPSLOPE. LARGE SURFACE HIGH BUILDS IN BEHIND...WITH
CLEARING SKIES AND COOLER TEMPERATURES.
LEANED TOWARDS THE COOLER SIDE OF MOS TUESDAY IN THE SOUTHEAST WITH
THICKER CLOUDS AND RAIN...AND MORE MIDDLE-OF-THE-ROAD TO THE
NORTHWEST. MET/MAV BLEND TUESDAY NIGHT. PREFERRED COOLER VALUES
WEDNESDAY WITH THE NORTHEAST FLOW BRINGING IN 1-3C H850 AIR.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
MODELS CONTINUE TO DIFFER WITH THE HANDLING OF THE REMNANTS OF
HURRICANE IDA. 12Z NAM APPEARS TO BE TRENDING TOWARDS A DRIER
SOLUTION FOR THURSDAY...AS IT INDICATES THE LOW PRESSURE SYSTEM OVER
THE SE U.S....AND ITS ASSOCIATED MOISTURE WILL CONTINUE TO MOVE
SOUTH OF THE REGION. 12Z GFS CONTINUES TO INDICATE THE REMNANTS OF
HURRICANE IDA WILL MOVE NORTHEAST OVER THE REGION EARLY THIS
WEEK...WITH PRECIPITATION CONTINUING TO WRAP AROUND THE BACK SIDE OF
THE LOW INTO THE REGION FOR THURSDAY. 00Z RUN OF THE ECMWF ALSO
INDICATED THE LOW PRESSURE CENTER WOULD MOVE NORTHEAST OVER THE
REGION...BUT WOULD MOVE OFFSHORE BY THURSDAY. HOWEVER...12Z RUN OF
THE ECMWF NOW SEEMS TO BE MORE IN LINE WITH THE 12Z NAM...TRENDING
TOWARDS A DRIER SOLUTION ON THURSDAY AS THE LOW PRESSURE CENTER
REMAINS OVER THE SE U.S....BEFORE SLIDING OFF TO THE SOUTH AND EAST
LATE WED. FOR NOW HAVE TRENDED THE FORECAST MORE TOWARDS THAT OF
HPC...ECMWF...AND NAM...WHICH KEEPS THE FORECAST REGION DRY FOR
THURSDAY. HIGH PRESSURE THEN TAKES CONTROL FOR MUCH OF THE REMAINDER
OF THE FORECAST PERIOD...FOR DRY CONDITIONS AND A GRADUAL WARM UP IN
TEMPERATURES. UNSETTLED WEATHER RETURNS TO THE FORECAST AREA LATE IN
THE PERIOD AS ANOTHER LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT
MOVE IN FROM THE WEST.
AVIATION /08Z MONDAY THROUGH FRIDAY/
BKN TO OVC HIGH CLOUDS AOA 20 THSD FT TODAY WITH SCT TO BKN AROUND
15 THSD FT AFTER 00Z TONIGHT.
SOME 3 TO 5 MILES UNDER THE SHALLOW INVERSION IN THE COLDER MOUNTAIN
VALLEYS NEAR TOWNS...SUCH AS EKN VCNTY THROUGH 13Z...DUE TO
HAZE...FOG...SMOKE. OTHERWISE SOME 5 TO 6 MILES IN URBAN RIVER
VALLEYS AROUND 12Z.
EVEN AFTER THE SHALLOW INVERSION BURNS OFF IN THE RIVER VALLEYS AFTER
14Z...FORECASTING A ISOTHERMAL STABLE LAYER WITH LOW MIXING HEIGHTS
THROUGH THE DAY. HAZE AND POLLUTION COULD BUILD UP...ESPECIALLY IN
THE URBAN RIVER VALLEYS SUCH AS THE OHIO AND THE KANAWHA. SO KEPT
SOME 5 TO 6 MILE VISIBILITY THROUGHOUT THE DAY.
AFTER 06Z TUESDAY...
NO SIGNIFICANT WEATHER EXPECTED AT THIS TIME.
RLX WATCHES/WARNINGS/ADVISORIES
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
SYNOPSIS...KTB/CL
NEAR TERM...KTB
SHORT TERM...CL
LONG TERM...SL
AVIATION...KTB
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