535
FXUS62 KCAE 150826
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
326 AM EST SUN DEC 15 2024
SYNOPSIS
WEAK COLD AIR DAMMING WILL DEVELOP TODAY, WITH BELOW AVERAGE
TEMPS EXPECTED. WELL ABOVE NORMAL TEMPS ARE EXPECTED MONDAY
THROUGH WEDNESDAY, WITH RAIN CHANCES INCREASING BY MID-WEEK AS
WELL. COLDER AIR RETURNS BY NEXT WEEKEND WITH A DEEP TROUGH
DIGGING INTO THE EASTERN US.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- COMPLEX SYNOPTIC SITUATION WITH A LARGE GRADIENT ACROSS THE
FORECAST AREA TODAY
RIDGE OF HIGH PRESSURE WILL BE ACROSS THE UPSTATE TODAY AS AN
UPPER LEVEL DISTURBANCE MOVES IN FROM THE WEST. THIS WILL
PRODUCE WEDGE CONDITIONS OVER THE WESTERN PORTIONS OF THE
FORECAST AREA WHILE THE CENTRAL AND EASTERN PORTIONS SEE MUCH
BETTER CONDITIONS. CURRENT REGIONAL WSR-88D IMAGERY SHOWS SOME
LIGHT RAIN DEVELOPING OVER THE UPSTATE HOWEVER THIS WILL BE
INTERACTING WITH THE SURFACE RIDGE AND MUCH OF THE RAIN PUSHING
NORTHEASTWARD. THROUGH DAYBREAK EXPECT A FEW SHOWERS TO DEVELOP
IN THE FAR WESTERN REACHES OF THE FORECAST AREA WHILE THE
REMAINDER OF THE AREA SEES MOSTLY CLOUDY SKIES.
SITUATION WILL BE SLOW TO CHANGE THROUGH THE DAY AS THE UPPER
LEVEL TROUGH SLIDES NORTHEASTWARD AND THE SURFACE RIDGE REMAINS
IN PLACE. WITH A BIT OF ISENTROPIC ASCENT OVER THE CENTRAL AND
WESTERN MIDLANDS EXPECT A FEW LIGHT SHOWERS MAINLY CONTAINED TO
THE WESTERN MIDLANDS AS DYNAMIC SUPPORT WILL REMAIN WELL
NORTHWEST OF THE AREA. THIS WILL KEEP THE WESTERN HALF OF THE
FORECAST AREA UNDER MOSTLY CLOUDY SKIES WITH DECREASING CLOUDS
IN THE EASTERN MIDLANDS AND SOUTHERN CSRA THROUGH THE AFTERNOON.
TEMPERATURES WILL FOLLOW A SIMILAR TREND WITH THE CLOUDS WITH A
SUBSTANTIAL GRADIENT FOR AFTERNOON HIGHS. EXPECT LOW 50S IN THE
WESTERN MIDLANDS AND NORTHERN CSRA WITH MID 50S ALONG THE I-20
CORRIDOR AND LOW 60S IN THE EASTERN MIDLANDS AND SOUTHERN CSRA.
CHANGE WILL BE SLOW THROUGH TONIGHT AS THE RIDGE OF HIGH
PRESSURE REMAINS ENTRENCHED OVER THE UPSTATE WHILE THE UPPER
LEVEL TROUGH PUSHES AWAY FROM THE REGION. THIS WILL KEEP MOSTLY
CLOUDY SKIES OVER THE WESTERN HALF OF THE FORECAST AREA WITH
DECREASING CLOUDS IN THE EAST. OVERNIGHT LOWS WILL BE IN THE LOW
TO MID 40S.
SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/
KEY MESSAGE(S):
- IMPROVING CONDITIONS FOR MONDAY
- WELL ABOVE NORMAL TEMPS EXPECTED MONDAY AND TUESDAY
IN THE WAKE OF THE SHORTWAVE TROUGH ON SUNDAY, SHORTWAVE RIDGING IS
EXPECTED TO PUSH INTO THE REGION ON MONDAY, DEVELOPING TO ZONAL FLOW
BY TUESDAY. SURFACE HIGH PRESSURE SHOULD REMAIN IN PLACE TO START
MONDAY BUT GUIDANCE SUGGESTS THAT THE SURFACE HIGH WILL BEGIN
TO FILL AND WEAKEN THROUGHOUT THE DAY. THIS SHOULD LEAD TO A
GRADUAL WIND SHIFT FROM NORTHEASTERLY TO EASTERLY TO
SOUTHEASTERLY THROUGH THE DAY. SO THE EARLY CAD CONDITIONS THAT
MAY REDEVELOP TONIGHT SHOULD GENERALLY BEGIN TO LESSEN
THROUGHOUT THE DAY ON MONDAY. THE NORTHERN FA MAY CONTINUE TO
SEE CLUD COVER AND COOLER TEMPS BUT IN GENERAL EXPECTING CLOUDS
TO BECOME LESSER THROUGH THE DAY. WITH THE RISING HEIGHTS AND
SHORTWAVE RIDING, TEMPS ARE FORECAST TO BE REALLY NICE AND UP
INTO THE MID TO UPPER 60S FOR MANY. OVERNIGHT ON MONDAY, HIGH
CLOUDS SHOULD PUSH BACK INTO THE REGION AHEAD OF ANOTHER
APPROACHING TROUGH. LOOK FOR LOWS IN THE MID TO UPPER 40S.
TUESDAY LOOKS TREMENDOUS. MID TO HIGH LEVEL CLOUDS ARE EXPECTED
AS THE SHORTWAVE TROUGH MOVES TO OUR NORTH WHILE A WEAKENING
FRONT APPROACHES THE AREA. NOT EXPECTING PRECIP WITH THIS GIVEN
THE FORCING BEING WELL TO OUR NORTH. HIGH SHOULD APPROACH
15F-20F ABOVE NORMAL IN THE LOW TO MID 70S ACROSS THE AREA,
ESPECIALLY WITH SOME WEAK COMPRESSIONAL HEATING AHEAD OF THAT
WEAKENING FRONT. OVERNIGHT, LOOK FOR TEMPS TO CONTINUE THAT
WARMTH WITH LOWS FORECAST TO BE IN THE LOW OR MID 50S.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
KEY MESSAGE(S):
- LITTLE CHANGE IN THE FORECAST THINKING FOR THE LONG TERM
PERIOD.
- WARM WEATHER WED/THUR
- RAIN CHANCES ON WED/THUR, WITH COOLER TEMPS ARRIVING FRI/SAT
THE DETAILS OF THE LONGER TERM ARE BEGINNING TO COME INTO BETTER
VIEW AS GUIDANCE GETS A BETTER HANDLE ON THE SYNOPTIC PATTERN DURING
THIS TIME FRAME. STILL EXPECTING TROUGHING ACROSS THE EASTERN US FOR
MUCH OF THIS PERIOD, WITH MUCH COOLER TEMPS BY THE END OF THE PERIOD
INTO NEXT WEEKEND. WEDNESDAY STILL LOOKS QUITE WARM, THOUGH, AS A
LOW PRESSURE SYSTEM AND COLD FRONT ARE FORECAST TO GET ORGANIZED TO
OUR WEST. RIDGING IS FORECAST TO PRECEDE THIS, AND WITH SOUTHERLY
FLOW AHEAD OF THE FRONT, TEMPS ARE LIKELY TO JUMP INTO THE 70S
AGAIN DESPITE INCREASING CLOUDS AND RAIN CHANCES THROUGH THE
DAY. ENSEMBLES AND OPERATIONAL MODELS HAVE GRADUALLY LOWERED
RAIN CHANCES IN GENERAL DURING THIS PERIOD. THEY'VE TRENDED
QUICKLY OVER THE PAST 4-5 RUNS TO A LESS AMPLIFIED, MORE COMPACT
AND FASTER NORTHERN STREAM SHORTWAVE PUSHING TO OUR NORTH. A
COLD FRONT SHOULD ACCOMPANY THIS ON WEDNESDAY NIGHT, BUT
PRECIPITATION CHANCES ARE STILL SORT OF UP IN THE AIR. LREF
MEMBERS HAVE ALL BACKED OFF ON RAINFALL PROBABILITIES IN THE
WED/THUR TIMEFRAME BUT THEY ALL STILL HAVE DECENT PROBABILITIES
OF RAINFALL. HOWEVER, IF THE MODELS CONTINUE TO TREND TOWARDS
THE SHORTWAVE REMAINING NORTH OF THE AREA, WE ARE LIKELY TO SEE
LESSER RAINFALL CHANCES. TRANSIENT HIGH PRESSURE IS FORECAST TO
PASS THROUGH ON THUR/FRI WITH A COOL DOWN EXPECTED. THEN,
ENSEMBLES AND OPERATIONAL MODELS ARE IN GOOD AGREEMENT THAT
ANOTHER, DEEPER TROUGH SHOULD SHIFT INTO THE REGION AND USHER IN
A COLD AIRMASS FOR NEXT WEEKEND. ECMWF EFI IS ALREADY SIGNALING
TO ANOMALOUS COLD IN THE DAYS 7-9 PERIOD (THE END OF THIS
PERIOD AND JUST BEYOND IT). SO BEYOND FRIDAY, LOOK FOR THE
REALLY COOL TEMPS TO POTENTIALLY RETURN.
AVIATION /09Z SUNDAY THROUGH THURSDAY/
RESTRICTIONS EXPECTED THROUGH MIDDAY THEN IMPROVING.
RIDGE OF HIGH PRESSURE REMAINS CENTERED ACROSS THE UPSTATE WITH
NORTHEAST FLOW PERSISTING OVER THE TERMINALS. WITH MOIST LOW
LEVELS CIGS HAVE CONTINUE TO SLOWLY LOWER WITH ALL TAF SITES
CURRENTLY MVFR AND EXPECTED TO REMAIN SO THROUGH THE FIRST HALF
OF THE PERIOD. A MID LEVEL DISTURBANCE WILL BE MOVING NORTHWEST
OF THE AREA THROUGH THIS AFTERNOON AND AS IT MOVES AWAY THIS
AFTERNOON EXPECT IMPROVING CONDITIONS. BY 18Z EXPECT ALL SITES
TO BE VFR HOWEVER SCATTERED LOWER CLOUDS WILL LIKELY PERSIST
INTO THE LATE AFTERNOON HOURS. WINDS WILL BE NORTHEASTERLY AT 10
KNOTS OR LESS THROUGH THE DAY THEN DIMINISH TO LIGHT AND
VARIABLE WITH SUNSET.
EXTENDED AVIATION OUTLOOK...INCREASING POTENTIAL FOR SHOWERS,
POSSIBLE THUNDERSTORMS, AND ASSOCIATED RESTRICTIONS ON WEDNESDAY.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
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