022
FXUS62 KCAE 201038
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
638 AM EDT SUN SEP 20 2026
WHAT HAS CHANGED
PRECIPITATION CHANCES FOR DIURNALLY DRIVEN CONVECTION TODAY
HAVE DECREASED. AVIATION DISCUSSION UPDATED FOR 12Z TAFS.
KEY MESSAGES
- 1. ABOVE AVERAGE TEMPERATURES AND INCREASED CHANCES FOR
SHOWERS AND STORMS CONTINUE INTO EARLY NEXT WEEK.
- 2. COOLER AND DRIER AIR RETURNS BY THE MIDDLE OF NEXT WEEK
BUT FORECAST UNCERTAINTY REMAINS.
DISCUSSION
KEY MESSAGE 1: ABOVE AVERAGE TEMPERATURES AND INCREASED CHANCES
FOR SHOWERS AND STORMS CONTINUE INTO EARLY NEXT WEEK.
A FEW CLUSTERS OF SHOWERS AND THUNDERSTORMS CONTINUE TO OUR
WEST AND DRIFTING SOUTHWARD EARLY THIS MORNING ALONG REMNANT
OUTFLOWS. ACTIVITY SHOULD REMAIN LIMITED, THOUGH HEAVY DOWNPOURS
CANNOT BE COMPLETELY RULED OUT.
UNSETTLED WEATHER REMAINS OVER THE AREA THE NEXT FEW DAYS, WITH
ISOLATED TO SCATTERED CONVECTION EXPECTED TODAY THROUGH EARLY
NEXT WEEK. ABOVE NORMAL TEMPERATURES AND PWATS OVER 1.75 INCHES
WILL SUPPORT SEASONABLE INSTABILITY. GIVEN THE RELATIVELY WEAK
FORCING, CONVECTION TODAY AND MONDAY SHOULD REMAIN LIMITED AND
DIURNAL IN NATURE. BETTER CHANCES FOR PRECIPITATION IS EXPECTED
TUESDAY INTO WEDNESDAY AS THE UPPER-AIR PATTERN EVOLVES AND A
FRONT NEARS. A MID- LEVEL LOW CURRENTLY OVER THE FAR EASTERN
GULF IS FORECAST TO LIFT NORTHWARD ALONG THE EASTERN SEABOARD,
WHILE DEVELOPING TROUGHING MOVES IN FROM THE MIDWEST. THESE
FEATURES WILL PROVIDE INCREASING SYNOPTIC FORCING AND SUPPORT
GREATER COVERAGE OF SHOWERS AND STORMS. OVERALL, THE SEVERE
THREAT REMAINS LOW. HOWEVER LOCALLY HEAVY RAIN WILL REMAIN
POSSIBLE, WITH THE POTENTIAL INCREASING TUESDAY AND WEDNESDAY AS
COVERAGE BECOMES MORE WIDESPREAD.
KEY MESSAGE 2: COOLER AND DRIER AIR RETURNS BY THE MIDDLE OF
NEXT WEEK BUT FORECAST UNCERTAINTY REMAINS.
TROUGHING OVER THE MIDWEST WILL SHIFT EASTWARD THROUGH THE
WEEK, SUPPORTING THE DEVELOPMENT OF A ROBUST AREA OF HIGH
PRESSURE THAT BUILDS SOUTHWARD INTO THE MID-ATLANTIC. HOWEVER,
CONSIDERABLE UNCERTAINTY REMAINS REGARDING THE EXTENT OF SURFACE
RIDGING, AS REFLECTED BY THE SPREAD AMONG ENSEMBLE MEMBERS AND
LREF CLUSTERS. THE DEGREE OF MOISTURE ADVECTION ATOP THE
POTENTIAL SURFACE WEDGE WILL LIKELY DEPEND ON THE TIMING AND
STRENGTH OF THE AFORMENTIONED TROUGHING. THE ECMWF REMAINS
WEAKER AND SHOWERS, MAINTAINING A MORE SOUTHWESTERLY FLOW ALOFT
ALLOWING GREATER MOISTURE TO OVERRUN THE SURFACE WEDGE. THE GFS
AND NAM FAVOR A STRONGER TROUGH WITH MORE NORTHWESTERLY TO
NORTHERLY FLOW RESULTING IN DIRER AIR.
GIVEN THE CONTINUED SPREAD, CONFIDENCE REMAINS LOW FROM
WEDNESDAY THROUGH LATE WEEK, PARTICULARLY REGARDING TEMPERATURES
AND POPS. WIDESPREAD PRECIPITATION APPEARS UNLIKELY, BUT SHOULD
SUFFICIENT MOISTURE AND ISENTROPIC LIFT DEVELOP OVER THE
POTENTIAL WEDGE, TYPICAL CAD PRECIPITATION CANNOT BE RULED OUT,
INCLUDING PERIODS OF LIGHT STRATIFORM RAIN/DRIZZLE.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
POSSIBLE MVFR/IFR RESTRICTIONS TOWARDS SUNRISE, THEN VFR CONDITIONS
FOR THE REMAINDER OF THE DAY.
SHOWERS HAVE FINALLY DISSIPATED THIS MORNING ACROSS THE AREA. IN
THEIR WAKE, SOME AREAS OF LOW CLOUDS AND PATCHY FOG HAVE
DEVELOPED, MAINLY WHERE THERE'S BEEN SOME THINNING OUT OF HIGH
LEVEL CLOUDINESS FROM THE EARLY SHOWER/STORM ACTIVITY.
CONFIDENCE HAS INCREASE SOMEWHAT THAT MANY AREAS SHOULD SEE AT
LEAST SOME MVFR RESTRICTIONS DEVELOPING BY 12Z. ANY LOW CIGS
AND/OR VIS SHOULD LIFT/IMPROVE BETWEEN 14Z-15Z, WITH A RETURN
TO PRIMARILY VFR CONDITIONS BY LATE MORNING. WINDS GENERALLY
LIGHT AND FROM THE EAST. AS FOR AFTERNOON CONVECTION, BLENDED
GUIDANCE SHOWING MOSTLY A DRY FORECAST THIS UPCOMING AFTERNOON,
SO FOR NOW NO MENTION OF ANY RAINFALL. EVEN SO, WITH NUMEROUS
SURFACE BOUNDARIES AROUND FROM YESTERDAY AND LAST NIGHT'S ROUND
OF SHOWERS AND STORMS, CAN NOT COMPLETELY RULE OUT SOME ISOLATED
ACTIVITY DEVELOPMENT THIS AFTERNOON.
EXTENDED AVIATION OUTLOOK...CHANCES FOR SHOWERS AND/OR
THUNDERSTORMS WILL CONTINUE THROUGH EARLY NEXT WEEK. MORNING
CIG/VSBY RESTRICTIONS ARE POSSIBLE AS WELL.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...ND
AVIATION...73
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