FXUS62 KCAE 301142
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
641 AM EST MON NOV 30 2009
.SYNOPSIS...
A COLD FRONT WILL MOVE THROUGH THE FORECAST AREA THIS AFTERNOON
BRINGING SOME RAIN SHOWERS AS IT PASSES. A STRONG LOW PRESSURE
SYSTEM WILL IMPACT THE AREA ON WEDNESDAY AND WEDNESDAY NIGHT...BRINGING
POTENTIALLY SIGNIFICANT RAINFALL. COLD HIGH PRESSURE WILL SETTLE
IN FOR THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE CONTINUES TO RETREAT OFF THE EAST COAST AS A COLD
FRONT MOVES THROUGH THE OHIO AND TENNESSEE VALLEYS EARLY THIS
MORNING. REGIONAL RADAR IS SHOWING A BAND OF SHOWERS WITH EMBEDDED
THUNDERSTORMS EXTENDING FROM EASTERN KENTUCKY SOUTHWESTWARD TO
LOUISIANA. THE BEST DYNAMICS WILL PASS BY JUST TO THE NORTH AND
WESTERLY FLOW OVER THE MOUNTAINS SHOULD LIMIT THE AMOUNT OF
PRECIPITATION THAT ACCUMULATES OVER THE MIDLANDS...BUT THERE WILL
LIKELY BE SCATTERED SHOWERS THAT PASS THROUGH TODAY. THE BEST
CHANCES WILL BE ACROSS THE FAR NORTH AND HAVE BUMPED UP POPS TO
LIKELY IN THE NORTHERN MIDLANDS WHILE KEEPING CHANCE POPS
ELSEWHERE.
THE FRONT WILL PUSH THROUGH QUICKLY THIS AFTERNOON AND DRIER AIR
WILL FILTER IN FROM THE WEST THIS EVENING. SHOULD SEE DRY
CONDITIONS OVERNIGHT SAVE FOR A STRAY SHOWER EARLY IN THE EASTERN
MIDLANDS. TEMPERATURES TODAY WILL BE LIMITED BY INCREASING CLOUDS
AND THE PRECIPITATION ALONG THE FRONT...BUT WILL DROP INTO THE 30S
AND LOWER 40S OVERNIGHT.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
A TRANSIENT SURFACE HIGH PRESSURE SYSTEM WILL MOVE OVER THE
FORECAST AREA ON TUESDAY INTO TUESDAY EVENING BEFORE SHIFTING OFF
THE COAST BY EARLY WEDNESDAY AS A VERY STRONG LOW PRESSURE SYSTEM
TRACKS ACROSS THE SOUTHERN UNITED STATES. A STRONG WARM ADVECTION
PATTERN DEVELOPS TUESDAY NIGHT ALONG THE GULF COAST STATES AND
SPREADS NORTHEASTWARD TOWARD THE FORECAST AREA BY WEDNESDAY
MORNING.
THIS IS A DIFFICULT FORECAST FOR A POTENTIALLY HIGH IMPACT RAIN
EVENT DUE TO SOME MODEL DIFFERENCES IN THE TIMING AND LOCATION OF
THE SURFACE LOW AS IT MOVES QUICKLY NORTHWARD FROM THE GULF ON
WEDNESDAY AND WEDNESDAY NIGHT. MODEL CONSENSUS IS TO TAKE THE
SURFACE LOW WEST OF THE FORECAST AREA RESULTING IN STRONG
SOUTHERLY LOW LEVEL WINDS OF 50 TO 65 KNOTS OUT OF THE SOUTH TO
SOUTHEAST. THIS RESULTS IN STRONG ISENTROPIC LIFTING AND MOISTURE
FLUX OVER THE AREA...AND WILL BE COINCIDING WITH STRONG JET
DYNAMICS AS THE RIGHT ENTRANCE REGION OF THE JET BECOMES SITUATED
OVER THE SOUTHEAST. EXPECT WIDESPREAD MODERATE...TO AT
TIMES...HEAVY RAIN TO OCCUR ACROSS THE FORECAST AREA WEDNESDAY
WITH THE HIGHEST QPF AMOUNTS BEING FOCUSED IN THE WESTERN MIDLANDS
AND IN THE UPSTATE OF SOUTH CAROLINA. WILL CONTINUE CATEGORICAL
POPS ON WEDNESDAY BUT WILL LEAVE OUT MENTION OF THUNDER SINCE
ATMOSPHERE REMAINS STABLE WITH WEAK WEDGE DEVELOPING. TEMPERATURES
WILL SUFFER DUE TO THE CLOUDS AND DEVELOPING EASTERLY FLOW AND
MODERATE PRECIPITATION...HOLDING HIGHS IN THE 50S ACROSS MOST OF
THE AREA.
AS THE SURFACE LOW LIFTS NORTHWARD WEDNESDAY EVENING THE FORECAST
AREA WILL LIKELY MOVE INTO THE WARM SECTOR AND BECOME SOMEWHAT
UNSTABLE AS LIFTED INDEX VALUES DROP TO AROUND -2C...SO WILL
INCLUDE THUNDER IN THE WEDNESDAY EVENING PERIOD. TEMPERATURES WILL
BE QUITE TRICKY AS WELL...AS THEY COULD REMAIN STEADY OR SLOWLY
RISE THROUGH THE NIGHT AND THEN POSSIBLY FALL AGAIN DEPENDING ON
HOW FAST THE COLD FRONT PUSHES THROUGH EARLY THURSDAY MORNING.
EXPECTING UPWARDS OF 1-2 INCHES ACROSS MUCH OF THE FORECAST AREA
THROUGH THIS EVENT WITH SOME LOCATIONS EXCEEDING 2.5 INCHES.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
SKIES WILL BE CLEARING WITH BREEZY WESTERLY WINDS IN THE WAKE OF
THE STRONG STORM SYSTEM MOVING INTO THE NORTHEASTERN STATES ON
THURSDAY. STRONG HIGH PRESSURE WILL BUILD INTO THE AREA THROUGH
SATURDAY AND REMAIN OVER THE SOUTHEAST INTO SUNDAY. THE AIRMASS
WILL BE QUITE CHILLY AND WE SHOULD SEE TEMPERATURES WELL BELOW
NORMAL FRIDAY THROUGH SUNDAY WITH MUCH OF THE EAST COAST UNDER THE
INFLUENCE OF AN UPPER TROUGH. THERE WILL BE LITTLE CHANCE FOR
PRECIPITATION DURING THIS PERIOD.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
A COLD FRONT APPROACHING THE SRN APPALACHIANS THIS MORNING WILL
CROSS THE TAF SITES AFTER 21Z. EXPECTED MAINLY VFR CONDITIONS. MAY
SEE A BRIEF PERIOD OF MVFR CIG/VSBY AHEAD OF THE FRONT IN THE 20Z TO
02Z TIME-FRAME. MODELS STILL INDICATING MOST OF THE SHOWERS WILL DRY
UP AS THEY CROSS THE MOUNTAINS AND WINDS AT LOW LEVELS BECOME
MORE WESTERLY. BETTER CHANCE OF SHOWERS HOLDING TOGETHER NORTH OF
KCAE/KCUB. SOUTHWEST WINDS INCREASING TO AROUND 10 KTS TODAY. MAY
SEE A GUST NEAR 20 KTS AROUND LATE MORNING. WINDS SHIFTING NORTHWEST
THIS EVENING THEN NORTH OVERNIGHT.
EXTENDED AVIATION OUTLOOK...MVFR TO IFR CONDITIONS EXPECTED
WEDNESDAY INTO THURSDAY MORNING AS A LOW PRESSURE SYSTEM CROSSES THE
THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
AVIATION...10
