684
FXUS62 KCAE 211903
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
303 PM EDT MON SEP 21 2026
WHAT HAS CHANGED
TEMPERATURES TRENDING COOLER FOR WEDNESDAY AND THURSDAY WITH COLD
AIR DAMMING CONDITIONS EXPECTED. AVIATION DISCUSSION UPDATED FOR 18Z
TAFS.
KEY MESSAGES
- 1. ABOVE AVERAGE TEMPERATURES AND CHANCES FOR SHOWERS AND STORMS
EARLY THIS WEEK.
- 2. MUCH COOLER CONDITIONS EXPECTED WEDNESDAY ONWARD, WITH
PERIODS OF SHOWERS MAINLY WEDNESDAY AND THURSDAY.
DISCUSSION
KEY MESSAGE 1: ABOVE AVERAGE TEMPERATURES AND CHANCES FOR SHOWERS
AND STORMS EARLY THIS WEEK.
ONE MORE DAY OF A STAGNANT PATTERN TODAY WITH A SHIFT BEGINNING LATE
TUESDAY. UPPER LOW OVER NORTHWEST FLORIDA WILL CONTINUE TO DRAW
MOISTURE INTO THE STATE OVER THE NEXT 24 HOURS. THIS DISTURBANCE
SHOULD FINALLY LIFT NORTHEAST OFF OUR COASTLINE TUESDAY IN RESPONSE
TO AN APPROACHING UPPER TROUGH MOVING THROUGH THE MIDWEST. HIGHS
TODAY WILL STILL PEAK IN THE LOW 90S WITH ISOLATED SHOWERS AND
THUNDERSTORMS AS A RESULT OF THE STRONG HEATING. BETTER COVERAGE OF
PRECIP CAN BE ANTICIPATED TUESDAY AS BETTER FORCING ASSOCIATED WITH
THE UPPER LOW GRAZES THE FORECAST AREA. ANOTHER SHORTWAVE MOVES
ACROSS THE REGION FROM THE WEST WHILE A SURFACE FRONT MOVES SOUTH
THEN SINK ACROSS THE MIDLANDS TUESDAY NIGHT WITH SCATTERED TO
WIDESPREAD SHOWERS AND STORMS.
KEY MESSAGE 2: MUCH COOLER CONDITIONS EXPECTED WEDNESDAY ONWARD,
WITH PERIODS OF SHOWERS MAINLY WEDNESDAY AND THURSDAY.
MODELS ARE GENERALLY CONVERGING NOW HIGH PRESSURE OVER THE NORTHEAST
WILL PUSH A WEDGE FRONT THROUGH OUR FORECAST AREA LATE TUESDAY INTO
WEDNESDAY. THE ONGOING SHOWERS AND CLOUD COVER WEDNESDAY MORNING
WILL LIKELY LIMIT DAYTIME HEATING, ESPECIALLY WITH COLD ADVECTION
OCCURRING AT THE SURFACE. THERE REMAINS SOME UNCERTAINTY REGARDING
HOW FAR SOUTH THE WEDGE FRONT WILL GO, AND IT IS EXPECTED TO HAVE A
TIGHT TEMPERATURE GRADIENT SETTING UP SOMEWHERE ACROSS THE SOUTHERN
MIDLANDS WEDNESDAY AFTERNOON. ALL SAID, THE TEMPERATURE DROP OF 10
TO 15+ DEGREES BETWEEN TUESDAY AND WEDNESDAY WILL BE VERY NOTICEABLE
NORTH OF THE FRONT. THERE WILL ALSO BE SOME BREEZY NORTHEAST WINDS
ACCOMPANYING THIS AIRMASS CHANGE. BLENDED GUIDANCE STRUGGLES IN
THESE SCENARIOS AND SO NAM/GFS DATA WAS BLENDED IN AND COLLABORATED
TO BETTER CAPTURE THE EXPECTED TEMPERATURES. IT CAN BE NOTED THAT WE
MAY STILL BE TOO WARM FOR THURSDAY, AND FUTURE PACKAGES MAY CONTINUE
TO DROP TEMPERATURES AS APPROPRIATE.
AN UPPER TROUGH THURSDAY WILL WORK TO SCOUR OUT THE WEDGE THROUGH
SOME PORTION OF THE DAY, WITH DRIER NORTHWEST FLOW EVENTUALLY MOVING
INTO THE AREA. HIGH PRESSURE WILL CONTINUE TO BE IN PLACE AT THE
SURFACE AND KEEP TEMPERATURES ON THE COOLER SIDE. BUT THE DRIER AIR
ALOFT WILL BRING PRECIP-FREE CONDITIONS BACK BY FRIDAY WITH HIGHS
STARTING TO REBOUND BACK A BIT CLOSER TO NORMAL. HIGHS SHOULD
GENERALLY REACH INTO THE UPPER 70S AND LOW 80S, WITH OVERNIGHT LOWS
IN THE UPPER 50S TO LOW 60S. OVERALL, THIS SHOULD PROVIDE OUR FIRST
REAL TASTE OF FALL WITH A REFRESHING CHANGE IN TEMPERATURES ARRIVING
JUST AS ASTRONOMICAL AUTUMN BEGINS ON TUESDAY!
AVIATION /18Z MONDAY THROUGH SATURDAY/
SCATTERED AND TOWERING CU HAVE DEVELOPED IN THE PAST COUPLE OF
HOURS ACROSS THE CSRA AND CENTRAL MIDLANDS, WHERE WEAK SURFACE
CONVERGENCE HAS SET UP ALONG THE I-20 CORRIDOR FROM AUGUSTA TO
COLUMBIA. SEVERAL SHOWERS AND A FEW THUNDERSTORMS HAVE DEVELOPED
NEAR THE AIK, AGS, DNL, CAE, AND CUB TERMINALS, WITH TSRA AND
LTG OBSERVED IN THE PAST HOUR AT CAE. HAVE ADDED PROB30 FOR
TSRA TO THESE TERMINALS THROUGH 22Z. ANY LINGERING SHOWER AND
THUNDERSTORM ACTIVITY AFTER THIS TIME SHOULD DIMINISH AROUND
SUNSET. ANOTHER ROUND OF VISIBILITY RESTRICTIONS WITH GROUND
FOG DEVELOPMENT ARE POSSIBLE AT ALL SITES LATE TONIGHT INTO
TUESDAY MORNING. KEPT THE POTENTIAL FOR PREVAILING MVFR
CONDITIONS AT MOST SITES AND IFR CONDITIONS AT OGB FROM 08-14Z.
ALSO ADDED TEMPOS BETWEEN 09-13Z FOR POTENTIAL FOR IFR AT MOST
SITES AND LIFR POSSIBLE AGAIN AT OGB (WHICH BRIEFLY FELL BELOW
1/4SM EARLIER THIS MORNING). ANY GROUND FOG SHOULD THEN BURN OFF
BY LATE TUESDAY MORNING AT ALL SITES WITH HEATING.
EXTENDED AVIATION OUTLOOK...INCREASING RAIN CHANCES AND
WIDESPREAD RESTRICTIONS ARE MOST LIKELY TUESDAY THROUGH THURSDAY
AS MOISTURE ADVECTION INCREASES AND A WEDGE SETS UP ACROSS THE
FORECAST AREA. SEASONAL, EARLY MORNING CIG/VIS RESTRICTIONS
WILL REMAIN POSSIBLE THROUGH MID-WEEK. DRIER CONDITIONS EXPECTED
BEGINNING FRIDAY.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...EC
AVIATION...SF
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