FXUS62 KCAE 141920
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
220 PM EST MON DEC 14 2009
.SYNOPSIS...
A WARM FRONT WILL APPROACH FROM THE SOUTH OVERNIGHT AND
BRING ANOTHER CHANCE OF RAIN BY THROUGH TUESDAY. COOL HIGH
PRESSURE WILL BUILD IN ON WEDNESDAY THROUGH THE END OF THE WEEK.
&&
.NEAR TERM /THROUGH TUESDAY/...
WEDGE CONDITIONS CONTINUE ACROSS THE FORECAST AREA TODAY WITH HIGH
PRESSURE CENTERED OVER THE EASTERN CAROLINAS...WITH A WARM FRONT
SITUATED ACROSS SOUTHERN GEORGIA. DENSE FOG THIS MORNING WAS SLOW
TO BURN OFF BUT CONDITIONS HAVE IMPROVED...ALTHOUGH THERE REMAIN
LOW CEILINGS ACROSS THE AREA.
A STRONG SURFACE LOW CURRENTLY MOVING INTO THE GREAT LAKES REGION
DRIVEN BY A TROUGH OVER THE CENTRAL PART OF THE COUNTRY IS
RESULTING IN BACKED UPPER FLOW OVER THE GULF COAST AND MOISTURE
WILL BE INCREASING FROM THE SOUTH. REGIONAL RADAR SHOWING LOTS OF
CONVECTION DEVELOPING ACROSS LOUISIANA...MISSISSIPPI AND
ALABAMA...SLOWLY LIFTING NORTHEASTWARD. THIS CONVECTION IS BEING
AIDED BY AN INCREASING LOW LEVEL JET WHICH IS BRINGING HIGH
THETA-E AIR OVER THE WARM FRONT.
RAIN SHOULD BEGIN TO MOVE INTO THE CSRA REGION LATE
AFTERNOON...EARLY THIS EVENING AND SPREAD OVER THE FORECAST AREA
OVERNIGHT. A FAST MOVING COLD FRONT OVER THE MISSISSIPPI VALLEY
WILL APPROACH THE MOUNTAINS BY TUESDAY MORNING AND WEST TO
NORTHWESTERLY FLOW ALOFT WILL HELP TO FOCUS THE RAIN ACROSS THE
MIDLANDS AND COASTAL AREAS THROUGH TUESDAY. GRADUALLY INCREASE
POPS THROUGH THE NIGHT TO CATEGORICAL SOUTHEAST AND LIKELY
ELSEWHERE...THEN GRADUALLY DECREASE POPS FROM THE NORTHWEST ON
TUESDAY AS THE FRONT PUSHES THROUGH. QPF IS LIKELY NOT GOING TO BE
VERY SIGNIFICANT DUE TO THE WEDGE HOLDING STRONG AND LIMITING THE
CONVECTIVE POTENTIAL AND A STRONG PRECIPITABLE WATER GRADIENT OVER
THE AREA WILL KEEP THE MORE SIGNIFICANT AMOUNTS SOUTH OF THE
FORECAST AREA. WILL INCLUDE THE MENTION OF SLIGHT CHANCE THUNDER
ACROSS THE CSRA AND SOUTHEASTERN MIDLANDS...ALTHOUGH THE WEDGE
CONDITIONS MAY HOLD THERE AS WELL AND PREVENT IT.
TEMPERATURES ARE LIKELY NOT GOING TO FALL TO MUCH OVERNIGHT AND
MAY ACTUALLY WARM A BIT ACROSS THE SOUTHERN FORECAST AREA AS THE
WARM FRONT LIFTS NORTHWARD. EXPECT FOG TO AGAIN BE PREVALENT
OVERNIGHT BUT RAINFALL SHOULD HELP LIMIT THE EXTENT OF POSSIBLE
DENSE FOG AND WILL NOT INCLUDE WITH THIS PACKAGE. TUESDAY HIGHS
SHOULD BE WARMER THAN TODAY WITH SOUTHERLY FLOW AHEAD OF THE COLD
FRONT AND THE MIXING DOWN OF WARM 850H AIR.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
HIGH PRESSURE QUICKLY BUILDS IN BEHIND THE DEPARTING FRONTAL
BOUNDARY TUESDAY NIGHT ON THE HEELS OF NORTHWESTERLY COLD
ADVECTION FLOW. THE SIGNIFICANT COLD AIR REMAINS BOTTLED UP ON THE
WEST SIDE OF THE MOUNTAINS AND ACROSS NORTHERN NORTH
CAROLINA. THERE REMAINS A SMALL CHANCE FOR RAIN IN THE EASTERN
COUNTIES DURING THE 00Z-05Z TIME FRAME TUESDAY NIGHT AS THE FRONT
PUSHES THROUGH.
WEDNESDAY AND THURSDAY WILL BE SEASONABLE WITH TEMPERATURES
SLIGHTLY BELOW NORMAL DESPITE MOSTLY SUNNY SKIES. OVERNIGHT LOWS
WILL LIKELY FALL TO NEAR OR BELOW FREEZING BOTH NIGHTS.
PRECIPITATION IS NOT EXPECTED WEDNESDAY THROUGH THURSDAY NIGHT.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
LITTLE CHANGES MADE TO THE EXTENDED DUE TO CONTINUED DIFFERENCES
AMONG THE MEDIUM RANGE MODELS. THE FORECASTED OVERALL UPPER
PATTERN IS A TRANSITION TO A LARGE TROUGH OVER THE EASTERN HALF OF
THE COUNTRY...BUT THE DISCREPANCIES ARE IN THE DETAILS OF A WHICH
SHORTWAVES ARE RESPONSIBLE FOR THE TRANSITION AND WHEN THEY MOVE
THROUGH.
THE GFS IS SHOWING A CLOSED WAVE OVER NORTHERN MEXICO BECOMING AN
OPEN WAVE BY THURSDAY NIGHT AND TRACKING A SURFACE LOW ACROSS THE
GULF OF MEXICO ACROSS CENTRAL FLORIDA ON FRIDAY. THE ECMWF ON THE
OTHER HAND IS A BIT SLOWER WITH THE EJECTING LOW FROM NORTHERN
MEXICO AND TRIES TO PHASE IT WITH NORTHERN STREAM ENERGY DROPPING
INTO THE PLAINS AND BRING A MORE SIGNIFICANT SYSTEM ACROSS THE
SOUTHEASTERN STATES...WITH A BETTER CHANCE OF PRECIPITATION
THROUGH THE WEEKEND.
THEREFORE...HAVE GONE WITH A PERSISTENCE FORECAST UNTIL MODEL DATA
COMES INTO BETTER AGREEMENT. STILL SHOULD SEE TEMPERATURES NEAR OR
SLIGHTLY BELOW NORMAL THROUGH THE PERIOD.
&&
.AVIATION /19Z MONDAY THROUGH SATURDAY/...
WEDGE CONTINUES TO HOLD OVER THE REGION. A WARM FRONT WILL
APPROACH FROM THE SOUTH TONIGHT THEN STALL OUT OVER THE AREA LATE
TONIGHT AND TUESDAY MORNING. THIS WILL KEEP IFR CONDITIONS THIS
AFTERNOON THROUGH TUESDAY MORNING. RAIN WILL ALSO MOVE OVER THE
AREA TONIGHT THROUGH TUESDAY MORNING. TUESDAY AFTERNOON...A COLD
FRONT WILL MOVE THROUGH FROM THE WEST ENDING THE RAIN. HOWEVER...
MVFR CIGS WILL COVER THE AREA TUESDAY AFTERNOON EVEN BEHIND THE
COLD FRONT.
MVFR CONDITIONS TUESDAY NIGHT AS COLD FRONT MOVES EAST. VFR CONDITIONS
WEDNESDAY THROUGH FRIDAY. MVFR CONDITIONS POSSIBLE AGAIN SATURDAY
AS ANOTHER SYSTEM APPROACHES.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&
$$
SYNOPSIS...HC
NEAR TERM...HC
SHORT TERM...HC
LONG TERM...HC
AVIATION...TTH
