FXUS62 KCAE 291123
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
622 AM EST SUN NOV 29 2009
.SYNOPSIS...
DRY HIGH PRESSURE WILL REMAIN OVER THE SOUTHEASTERN STATES THROUGH
TONIGHT. AN APPROACHING COLD FRONT WILL MOVE THROUGH THE FORECAST
AREA MONDAY AFTERNOON AND EVENING. A STRONG LOW PRESSURE SYSTEM
WILL IMPACT THE AREA ON WEDNESDAY...BRINGING SIGNIFICANT RAINFALL.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE REMAINS IN CONTROL OVER THE SOUTHEASTERN PART OF THE
COUNTRY THIS MORNING. SATELLITE IMAGERY IS SHOWING A BLANKET OF
HIGH CLOUDS MOVING OVER THE FORECAST AREA...ASSOCIATED WITH A
SHORTWAVE MOVING ACROSS THE GULF COAST STATES. HOWEVER...WITH
LITTLE MOISTURE AVAILABLE BELOW 500 MB THERE IS NO CHANCE FOR
PRECIPITATION THROUGH TONIGHT. THE CLOUDS SHOULD THIN OUT DURING
THE DAY AND ALLOW FOR A SUBSTANTIAL AMOUNT OF SUNSHINE TO PASS
THROUGH...ALLOWING TEMPERATURES TO APPROACH THE UPPER 60S TO
AROUND 70 THIS AFTERNOON.
CLOUDS WILL AGAIN INCREASE OVERNIGHT...IN THE FORM OF THICKER
CIRRUS AND THIS WILL HELP TO KEEP TEMPERATURES FROM DROPPING QUITE
AS COLD AS PREVIOUS NIGHTS.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
A NORTHERN STREAM SHORTWAVE WILL TRACK ACROSS THE NORTHERN PLAINS
INTO THE OHIO VALLEY AND EVENTUALLY THE NORTHEASTERN STATES BY
MONDAY EVENING. THIS WILL DRIVE A COLD FRONT THROUGH THE FORECAST
AREA LATE MONDAY AFTERNOON...BRINGING THE CHANCE FOR SOME RAIN
SHOWERS. PRECIPITABLE WATER VALUES ARE NOT THAT IMPRESSIVE WITH
THE FRONT AND STRONG WESTERLY FLOW ACROSS THE MOUNTAINS WILL LIMIT
PRECIPITATION CHANCES A BIT...BUT THE DYNAMICS WITH THE SYSTEM ARE
FAIRLY STRONG.
WILL CARRY LOW END LIKELY POPS ACROSS THE NORTHERN MIDLANDS FOR
MONDAY AFTERNOON WITH CHANCE POPS ELSEWHERE. THIS LOOKS LIKE IT
COULD BE A CASE OF WHERE IT LOOKS LIKE IT SHOULD RAIN A BIT BUT
QPF WILL BE QUITE LIGHT. THIS WILL ALSO BE A FAST MOVING FRONT AND
PRECIPITATION WILL NOT LAST LONG AND SHOULD BE EAST OF THE
FORECAST AREA BY 00Z TUESDAY.
TUESDAY LOOKS TO BE A SEASONAL DAY WITH PLENTY OF SUNSHINE AND
TEMPERATURES IN THE LOWER 60S AS HIGH PRESSURE BRIEFLY BUILDS IN
BEHIND THE DEPARTING FRONT FROM MONDAY EVENING.
A MORE SIGNIFICANT WEATHER SYSTEM IS SET TO IMPACT THE SOUTHEAST
AND EAST COAST ON WEDNESDAY INTO WEDNESDAY NIGHT AS A CUTOFF LOW
OVER THE DESERT SOUTHWEST EJECTS 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 VERY DYNAMIC SYSTEM
WITH MODELS SUGGESTING A POSSIBLE COUPLING OF THE NORTHERN AND
SOUTHERN STREAM JETS WHICH COULD ENHANCE PRECIPITATION ACROSS THE
AREA. A STRONG 850H JET OF AROUND 50-60 KNOTS OFF THE ATLANTIC
SHOULD USHER IN PLENTY OF MOISTURE AHEAD OF THE MAIN SHORTWAVE
WHICH IS EXPECTED TO CROSS THE AREA WEDNESDAY EVENING.
WILL CONTINUE TO CARRY THE INHERITED CATEGORICAL POPS FOR
WEDNESDAY WHILE BUMPING UP THE POPS LATE TUESDAY NIGHT AS THESE
WARM ADVECTION EVENTS SEEM TO ARRIVE EARLIER THAN MODELS SUGGEST
MOST OF THE TIME. DO NOT THINK THUNDER WILL BE AN ISSUE AT THIS
POINT AND WILL LEAVE OUT FOR NOW. TEMPERATURES WILL BE HELD DOWN
ON WEDNESDAY DUE TO THICKENING AND LOWERING CLOUDS AND
PRECIPITATION. QPF AMOUNTS AT THIS POINT ARE A BIT UNCERTAIN BUT
BUFKIT DATA SUGGESTS IT COULD BE ANOTHER SIGNIFICANT RAIN
EVENT...WITH UPWARDS OF 1-2 INCHES OF RAIN AND THIS IS IN LINE
WITH THE HPC QPF FORECAST.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
LITTLE CHANGE TO THE EXTENDED FORECAST. THE STRONG STORM SYSTEM
WILL EXIT THE FORECAST AREA EARLY THURSDAY AS STRONG HIGH PRESSURE
BUILDS IN FROM THE WEST...BRINGING COOLER AND DRIER AIR.
NORTHWESTERLY FLOW WILL BRING IN A CANADIAN AIRMASS WHICH WILL
RESULT IN WELL BELOW NORMAL TEMPERATURES FOR THE END OF THE WORK
WEEK INTO THE WEEKEND. HIGH SHOULD TOP OUT IN THE UPPER 50S TO
LOWER 60S ON THURSDAY AND THEN STRUGGLE THROUGH THE 50S ON FRIDAY
AND SATURDAY. A VERY DRY AIRMASS WILL PREVENT CHANCES OF
PRECIPITATION DURING THE EXTENDED FORECAST PERIOD.
&&
.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
VFR CONDITIONS THROUGH THE TAF PERIOD. HIGH CLOUDS WILL CROSS
THE TAF SITES AS A WEAK UPPER LEVEL DISTURBANCE CROSSES THE
REGION THIS MORNING. SOUTHWEST WIND LESS THAN 10 KNOTS.
EXTENDED AVIATION OUTLOOK...MVFR CONDITIONS POSSIBLE MONDAY AS A
COLD FRONT CROSSES THE AREA. MVFR TO IFR CONDITIONS EXPECTED
WEDNESDAY INTO WEDNESDAY NIGHT AS A LOW PRESSURE SYSTEM CROSSES THE
AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
