Area Forecast Discussion
Issued by NWS Columbia, SC

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FXUS62 KCAE 171816
AFDCAE

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
216 PM EDT WED SEP 17 2014

.SYNOPSIS...
WEAK FRONT ACROSS THE EASTERN MIDLANDS WILL PUSH TO THE COASTAL
PLAIN THIS AFTERNOON AND OFF THE COAST THURSDAY. HIGH PRESSURE
WILL BRING DRY WEATHER AND BELOW NORMAL TEMPERATURES TO THE AREA
FOR THURSDAY THROUGH THE WEEKEND. ANOTHER COLD FRONT WILL BRING A
CHANCE FOR SHOWERS AND THUNDERSTORMS EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
UPPER TROUGH OVER THE E CONUS...WITH A SERIES OF IMPULSES EXPECTED
TO MOVE THROUGH. LATEST SURFACE ANALYSIS SUGGESTS A FRONTAL BOUNDARY
IS STRETCHED ACROSS THE NORTHERN FORECAST AREA (FA)...WITH A
POSSIBLE WEAK SURFACE TROUGH NEAR THE SOUTHERN FA/CSRA. WEAK IN SITU
WEDGE/PERSISTENT LOW CLOUDS STILL AFFECTING MUCH OF THE NORTHERN
HALF OF THE FA. THESE BOUNDARIES IN ADDITION TO A POSSIBLE SEA
BREEZE COULD RESULT IN SCATTERED AFTERNOON AND EARLY EVENING
CONVECTION...FAVORING CENTRAL AND SOUTHERN AREAS WHERE BEST HEATING
AND INSTABILITY EXPECTED. MODEL GUIDANCE STILL INDICATING MIXED
RESULTS WITH RESPECT TO PLACEMENT AND EXTENT OF CONVECTION...BUT
THINK SLIGHT CHANCE POPS NORTH TO CHANCE POPS CENTRAL AND SOUTH ARE
IN ORDER. DRY AIR ALOFT NOTED IN WATER VAPOR IMAGERY COULD PROVIDE A
THREAT OF AN ISOLATED SEVERE STORM CAPABLE OF PRODUCING A STRONG
WIND GUST. ANY CONVECTION EXPECTED TO DISSIPATE BY LATE
EVENING...THEN FAIR WEATHER OVERNIGHT. LOW CLOUDINESS AND POSSIBLY
FOG EXPECTED TO DEVELOP LATE TONIGHT.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
THE UPPER TROUGH OVER THE EASTERN CONUS IS FORECAST TO DEEPEN
WITH A CUT OFF LOW DEVELOPING OVER SOUTHEAST GA ON FRIDAY. H5
TEMPERATURES ARE FORECAST AS LOW AS MINUS 11C. WEAK INSTABILITY IS
FORECAST FOR THE MIDLANDS AND CSRA WITH MODERATE INSTABILITY
FARTHER SOUTH BENEATH THE UPPER LOW. A LARGE AREA OF SURFACE HIGH
PRESSURE CROSSING SOUTHERN CANADA AND THE GREAT LAKES WILL MOVE
EAST TO THE NORTH ATLANTIC COAST. ALL MODELS FORECAST THE HIGH
PRESSURE TO RIDGE INTO OUR AREA BRINGING NORTHERLY WINDS AND COLD
AIR ADVECTION THROUGH FRIDAY NIGHT. EXPECT SEVERAL HARD TO TIME
WEAK SHORT WAVES TO CROSS THE ARE IN NORTHWEST FLOW ALOFT.
MOISTURE APPEARS TO BE SHALLOW...SO KEPT THE FORECAST DRY...BUT
INCREASED CLOUD COVER. THE 12Z MODELS HAVE BEGUN TO INCREASE POPS
ACROSS THE AREA BOTH THURSDAY AND FRIDAY. GIVEN SHALLOW MOISTURE
AND LACK OF OMEGA...WILL NOT FOLLOW.

HIGH TEMPERATURES WILL BE IN THE UPPER 70S TO LOWER 80S WITH
OVERNIGHT LOWS IN THE LOWER TO MIDDLE 60S.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
BOTH THE GFS AND ECMWF INDICATE WEAK CYCLONIC UPPER FLOW ACROSS THE
NORTHERN TIER STATES SATURDAY WITH A WITH CUTOFF LOW OFF THE
SOUTHEAST COAST. THE TROUGH IS PROGGED TO DEEPEN OVER THE EASTERN
CONUS THROUGH EARLY NEXT WEEK. WEDGE CONDITIONS WILL PERSIST ACROSS
THE FORECAST AREA SATURDAY AND SUNDAY WITH THE NEXT COLD FRONT
EJECTING THE WEDGE AS IT MOVES INTO THE REGION MONDAY. THIS WILL
KEEP DRY CONDITIONS OVER THE REGION THROUGH SUNDAY WITH LOW CHANCE
POPS MONDAY AND TUESDAY AS THE FRONT CROSSES THE FORECAST AREA.
GIVEN MOIST ONSHORE FLOW AND ABOVE AVERAGE POPS SHOWN BY THE GFS
ENSEMBLES...WILL KEEP LOW CHANCE POPS FOR WEDNESDAY, ALSO.
TEMPERATURES THROUGH THE LONG TERM WILL BE BELOW NORMAL.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
SATELLITE AND SURFACE OBS INDICATE PERSISTENT CLOUDINESS REMAINS
OVER MUCH OF THE FORECAST AREA (FA). IT APPEARS MVFR CIGS WILL
CONTINUE AT THE TERMINALS IN THE NEAR TERM...GRADUALLY BECOMING VFR
BY MID AFTERNOON. SURFACE BOUNDARIES AND DIURNAL HEATING EXPECTED TO
PROVIDE POSSIBILITY OF SCATTERED AFTERNOON AND EVENING SHOWER AND
THUNDERSTORM ACTIVITY. CHANCES NOT SUFFICIENT TO WARRANT INCLUSION
IN THE TAFS AT THIS TIME. WILL INCLUDE IN LATER ISSUANCES IF/WHEN
CONFIDENCE WARRANTS. LINGERING LOW LEVEL MOISTURE PLUS DRY AIR ALOFT
AND LIGHT SURFACE WINDS WILL PROVIDE THREAT OF FOG/STRATUS LATE
TONIGHT/EARLY THURSDAY MORNING. LATEST GUIDANCE SUGGESTING LOW CIGS
THE MAIN THREAT...WITH SOME VSBY RESTRICTIONS. A SLOW RETURN TO VFR
EXPECTED BY THURSDAY AFTERNOON.

EXTENDED AVIATION OUTLOOK...LATE NIGHT AND MORNING FOG/STRATUS
POSSIBLE THROUGH SATURDAY.

&&

.CAE WATCHES/WARNINGS/ADVISORIES...
SC...NONE.
GA...NONE.
&&

$$





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