333
FXUS62 KCAE 051145
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
745 AM EDT TUE AUG 5 2025
SYNOPSIS
UNUSUAL MID-SUMMER "COLD" AIR DAMMING LINGERS THROUGH THE
WORKWEEK BEFORE A COASTAL LOW ERODES THE WEDGE THIS WEEKEND.
BELOW NORMAL HIGH TEMPERATURES CAN BE EXPECTED EACH AFTERNOON
THROUGH AT LEAST SATURDAY DESPITE A GRADUAL WARMING TREND
WEDNESDAY INTO THE WEEKEND. SHOWER AND THUNDERSTORM CHANCES
STICK AROUND THIS WEEK, WITH THE POTENTIAL FOR LOCALLY HEAVY
RAINFALL EACH DAY.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- RAIN SHOWERS ACROSS THE CSRA AND WESTERN MIDLANDS WILL
DIMINISH BY MID-MORNING
- WEDGE CONDITIONS EXPECTED TO CONTINUE, ESPECIALLY NORTH OF
I20, TODAY
- SHOWERS AND THUNDERSTORMS LIKELY ALONG AND SOUTH OF THE WEDGE
BOUNDARY THIS AFTERNOON
THE PATTERN FOR THE PAST FEW DAYS IS FORECAST TO CONTINUE
THROUGH THE DAY TODAY. EARLY THIS MORNING, COPIOUS MOISTURE IS
STILL PRESENT ACROSS THE AREA WITH PWS IN THE 2"-2.2" RANGE.
STRONG MOISTURE TRANSPORT VECTORS ARE NOTED ACROSS THE WESTERN
FORECAST AREA AND INTO THE UPSTATE WITH FLOW ENHANCED IN THE
RIGHT-ENTRANCE REGION OF AN UPPER LEVEL JET STREAK. ISENTROPIC
LIFT IS ALSO NOTED IN ASSOCIATION WITH THIS FEATURE, WITH ALL OF
THIS LEADING TO WIDESPREAD RAIN ACROSS THE NORTHERN CSRA AND
WESTERN MIDLANDS AS OF THIS WRITING. THIS IS EXPECTED TO
CONTINUE FOR THE NEXT 6-8 HOURS AS THE RIGHT ENTRANCE REGION
PERSISTS OVER THE AREA, WITH AERIAL RAINFALL GENERALLY
DIMINISHING AFTER ~15Z AS THE JET STREAK PROPAGATES NORTHWARD
OUT OF THE AREA.
THE SETUP FOR TODAY LOOKS FAIRLY SIMILAR, WITH COPIOUS MOISTURE IN
PLACE ACROSS THE AREA AND PERSISTENT TROUGHING TO OUR WEST. SURFACE
RIDGING IN ASSOCIATION WITH THE STRONG HIGH PRESSURE WILL CONTINUE,
WITH AUGUST CAD CONDITIONS PERSISTING ALONG AND NORTH OF I20. EVEN
WITH THE RAIN PUSHING OUT MID-MORNING, STRATUS IS LIKELY TO HOLD
STRONG EVEN INTO EARLY AFTERNOON ALONG THE WEDGE BOUNDARY ITSELF,
MAKING IT DIFFICULT TO FORECAST JUST HOW FAR NORTH THE BOUNDARY
ACTUALLY MAKES IT. THIS MAKES HIGH TEMP FORECASTS CHALLENGING
TO SAY THE LEAST, AS THE LOCATION OF THIS WILL DELINEATE THE
LOCATIONS THAT STAY IN THE MID 70S AND THOSE THAT GET INTO THE
MID 80S THIS AFTERNOON. THE HREF ILLUSTRATES THIS WELL, WITH THE
IQR SPREAD FOR TEMPS ALONG THE I20 CORRIDOR THIS AFTERNOON IS
8F TO 10F. THIS DOES HAVE SENSIBLE WEATHER IMPACTS AS GUIDANCE
CONTINUES TO SHOW SCATTERED TO NUMEROUS SHOWERS AND STORMS
DEVELOPING ALONG AND SOUTH OF THE BOUNDARY THIS AFTERNOON. HREF
MEAN INSTABILITY IS GENERALLY 1000-1500 J/KG DOWN HERE, AND THIS
COINCIDES WELL WITH A WEAK SHORTWAVE THAT IS FORECAST TO PASS
THROUGH THE REGION THIS AFTERNOON. SEVERE WEATHER IS UNLIKELY
WITH MOIST ADIABATIC SOUNDINGS NOTED, BUT HEAVY RAINFALL COULD
CERTAINLY BE A PROBLEM. HREF AND REFS 6 HOUR LPMM GUIDANCE IS
SUGGESTING THAT ISOLATED RAINFALL TOTALS OF 2"+ ARE POSSIBLE.
FLASH FLOODING IS LIKELY TO BE THE PRIMARY THREAT WITH ANY
STORMS THAT DEVELOP. TONIGHT, LOOK FOR LOWS IN THE LOW TO MID
70S AGAIN WITH SHOWERS PROBABLY PERSISTING INTO THE OVERNIGHT
HOURS AGAIN.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/
KEY MESSAGE(S):
- LITTLE CHANGE IN THE THINKING FOR THE MIDDLE OF THE WEEK, WITH
WIDESPREAD SHOWERS AND BELOW AVERAGE TEMPS.
THE GENERAL SYNOPTIC PATTERN WILL REMAIN IN PLACE THROUGHOUT THE
SHORT TERM PERIOD. THE ONLY NOTABLE CHANGES WILL BE A WEAKENING OF
THE MID-UPPER LEVEL TROUGH AND THE SURFACE RIDGING LEE OF THE
APPALACHIANS WILL SLIGHTLY WEAKEN. BUT REGARDLESS, DEEP MOISTURE
ADVECTION WITH SOUTHERLY COMPONENT FLOW ALOFT AND NORTHEAST SURFACE
FLOW WILL CONTINUE THE WEDGE-LIKE SETUP AND DRIVE ISENTROPIC LIFT
THROUGHOUT THE MIDDLE OF THE WEEK. WITH BROAD SYNOPTIC SCALE
FAVORABILITY, PWAT'S UP NEAR 2.0", AND SOME MODEST ELEVATED CAPE,
WIDESPREAD SHOWERS ARE LIKE BOTH WEDNESDAY AND THURSDAY. RAINFALL
TOTALS ARE BIT UNCERTAIN DUE TO THE NATURE OF THIS RELATIVELY WEAKLY
FORCED AND ONLY LIMITED INSTABILITY SETUP; INHERENTLY SENSITIVE AND
TOUGH SETUP FOR GUIDANCE. BUT OVERALL, THESE WAVES OF SHOWERS AND
STORMS SHOULD YIELD A FAIRLY WIDESPREAD 1-2" ACROSS THE FORECAST
AREA WEDNESDAY AND THURSDAY, WITH HIGHEST TOTALS FOCUSED IN THE
WESTERN MIDLANDS. TEMPS WILL REMAIN BELOW AVERAGE DUE TO PERSISTENT
THICK CLOUD COVER AND PRECIP, BUT BY THURSDAY, ENOUGH SURFACE
HEATING SHOULD TRANSITION THE RAINFALL POTENTIAL TO BE MORE
DIURNALLY DRIVEN.
LONG TERM /FRIDAY THROUGH MONDAY/
KEY MESSAGE(S):
- CONTINUED WET PATTERN EXPECTED THROUGH THE LONG TERM PERIOD WITH
SOME OFFSHORE LOW PRESSURE LIKELY BY THE WEEKEND.
OVERALL, THE SYNOPTIC SCALE PATTERN WILL SLOWLY BECOME MORE DIFFUSE
AND WEAKER INTO THE LONG TERM PERIOD WITH SURFACE RIDGING WEAKENING
LEE OF THE APPALACHIANS ALONG WITH SOUTHWESTERLY FLOW ALOFT.
HOWEVER, PERSISTENT SOUTHEASTERLY 850-500MB FLOW WILL CONTINUE TO
DRIVE VERY HIGH MOISTURE ADVECTION INTO THE REGION WITH PWAT'S
CLIMBING OVER 2.0". THIS SOUTHEASTERLY FLOW INTO THE REGION WILL
LIKELY BE ENHANCED BY A DEVELOPING OFFSHORE LOW PRESSURE SYSTEM THAT
DEVELOPS ALONG A RESIDUAL BAROCLINIC ZONE. GUIDANCE GENERALLY KEEPS
THESE CIRCULATION QUITE BROAD, BUT THERE IS A NON-ZERO CHANCE IT
DEVELOPS SOME TROPICAL CHARACTERISTICS. REGARDLESS IT WILL LEAD TO
WIDESPREAD SHOWERS AND STORMS ARE LIKELY THROUGHOUT THIS PERIOD AS
THIS LOW SLOWLY PIVOTS UNDERNEATH THE WEAKENING SYNOPTIC SCALE FLOW
ALOFT. SINCE THE SURFACE RIDGING SHOULD WEAKEN SOME, THE SHOWERS-
STORMS SHOULD BE MORE DIURNALLY DRIVEN THEN WHAT WE SAW EARLIER IN
THE WEEK, PEAKING IN THE AFTERNOON AND EVENING. RAINFALL TOTALS ARE
QUITE VARIED ACROSS ENSEMBLE GUIDANCE BUT THE LACK OF SYNOPTIC
FORCING SHOULD KEEP PRECIP RELATIVELY WIDESPREAD AND DIURNALLY
DRIVEN; EC EFI DOESN'T REALLY HIGHLIGHT ANY PARTICULAR AREAS FOR
PERSISTENT HEAVY RAINFALL.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
WIDESPREAD RESTRICTIONS AREA AGAIN EXPECTED ACROSS THE AREA TODAY,
WITH THE WEDGE POTENTIALLY BREAKING FOR A FEW HOURS THIS AFTERNOON.
CEILING RESTRICTIONS ARE ONGOING AT THE TERMINALS THIS MORNING
WITH IFR TO LIFR CEILINGS BEING OBSERVED AT THE AUGUSTA
TERMINALS. CEILINGS ARE EXPECTED TO FALL TO IFR AT THE REMAINING
TERMINALS, THOUGH THERE IS A QUESTION AS TO WHEN AND WHERE THIS
HAPPENS. THE RAIN IS CURRENTLY PUSHING MOSTLY NORTHWEST OF THE
TAF SITES BUT ON AND OFF SHOWERS ARE POSSIBLE NEAR/OVER THE
TERMINALS THIS MORNING.
NAM AND HRRR GUIDANCE THEN SUGGESTS THAT THE WEDGE IN PLACE OVER
THE REGION WILL SLOWLY RETREAT NORTHWARD, WITH OGB MOST LIKELY
TO BREAK OUT THE MVFR CEILINGS THIS AFTERNOON. HEDGE TOWARDS
THAT AT AGS AND CAE BUT THE LINE BETWEEN CLOUDS AND SUN WILL
LIKELY RUN ALONG A LINE FROM AGS TO CAE CASTING A LOT OF
UNCERTAINTY ON THE FORECAST. WHAT DOES SEEM LIKELY IS THAT
WIDESPREAD SHOWERS AND THUNDERSTORMS WILL DEVELOP ALONG AND
SOUTH OF THE BOUNDARY THIS AFTERNOON. HAVE VCTS AT ALL SITES
FROM 19Z THROUGH 03Z, WHICH WILL LIKELY BE HONED A BIT
SUBSEQUENT TAF UPDATES.
STRATUS IS LIKELY TO DEVELOP AGAIN TONIGHT AS THE WEDGE
ADVANCES SOUTHWARD AGAIN. WINDS THROUGHOUT THE PERIOD SHOULD BE
NORTHEASTERLY OR EASTERLY BETWEEN 5 AND 10 KNOTS.
EXTENDED AVIATION OUTLOOK...FLIGHT RESTRICTIONS ARE POSSIBLE
EACH DAY WITH WIDESPREAD SHOWERS EXPECTED THROUGHOUT THE WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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