FXUS62 KCAE 300528
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
1222 AM EST MON NOV 30 2009
.SYNOPSIS...
DRY HIGH PRESSURE WILL REMAIN OVER THE SOUTHEASTERN STATES 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 POTENTIALLY SIGNIFICANT RAINFALL.
&&
.NEAR TERM /THROUGH MONDAY/...
CIRRUS HAS THINNED CONSIDERABLY OVER THE PAST COUPLE OF HOURS.
THIS HAS ALLOWED SURFACE TEMPERATURES TO DROP NEAR FORECAST LOWS.
SO WILL ISSUE QUICK UPDATE TO DROP LOWS INTO MAINLY THE LOWER 40S.
DEWPOINTS HAVE ALSO DROPPED TO UPPER 30S IN SOME LOCATIONS. EXPECT
OTHER DEWPOINTS TO FALL TO NEAR 40. SO FOG THREAT SHOULD BE
MINIMAL.
PREVIOUS DISCUSSION...
HIGH PRESSURE IS CURRENTLY CENTERED OFF THE SE COAST THIS
AFTERNOON. SOME INCREASE IN MID AND HIGH LEVEL CLOUDS THIS EVENING
AND TONIGHT WILL KEEP OVERNIGHT TEMPS IN THE LOW TO MID 40S.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY 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.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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. MODELS NOW SEEM
TO TREND IN KEEPING SFC LOW A BIT FARTHER TO THE WEST THAN
PREVIOUS MODEL RUNS.
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. WILL NOW INCLUDE A SMALL CHANCE OF THUNDER FOR
WEDNESDAY AFTERNOON GIVEN LATEST GFS BUFKIT DATA. 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.
BY SUNRISE THURSDAY MORNING...HIGH PRESSURE SHOULD BE BUILDING
FROM THE WEST BRINGING COOLER AND DRIER AIR. THE STRONG STORM
SYSTEM WILL EXIT THE FORECAST AREA EARLY THURSDAY. 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 /06Z MONDAY THROUGH FRIDAY/...
HIGH PRESSURE WILL REMAIN SOUTHEAST OF THE AREA OVERNIGHT.
A COLD FRONT APPROACHING FROM THE WEST WILL CROSS THE AREA MONDAY
EVENING. MAINLY VFR CONDITIONS ARE EXPECTED THE NEXT 24 HOURS.
HOWEVER...MVFR CONDITIONS ARE POSSIBLE IN THE VCNTY OF SHOWERS
LATE MONDAY FROM 20Z-02Z.
EXTENDED AVIATION OUTLOOK...MVFR TO IFR CONDITIONS EXPECTED
WEDNESDAY INTO WEDNESDAY NIGHT AS A LOW PRESSURE SYSTEM CROSSES
THE THE AREA.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
