938
FXUS62 KCAE 031721
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
121 PM EDT SUN MAY 3 2026
WHAT HAS CHANGED
CONFIDENCE IN PERIODS OF MODERATE TO HEAVY RAINFALL THURSDAY
HAS INCREASED SLIGHTLY. AVIATION UPDATED FOR 18Z TAFS.
KEY MESSAGES
- 1. PERIODS OF MODERATE TO HEAVY RAINFALL ARE EXPECTED DURING
THE MID WEEK WITH THE POTENTIAL SEVERE WEATHER.
DISCUSSION
KEY MESSAGE 1: PERIODS OF MODERATE TO HEAVY RAINFALL ARE
EXPECTED DURING THE MID WEEK WITH THE POTENTIAL SEVERE WEATHER.
THERE HAS NOT BEEN A SIGNIFICANT CHANGE IN THE OUTLOOK WITH AN
INCOMING SYSTEM FOR THE MID WEEK. OVERALL, THERE IS GOOD MODEL
CONSENSUS IN AN UPPER TROUGH SWINGING OUT OF THE NORTHERN CONUS
TOWARD THE REGION LATE WEDNESDAY INTO THURSDAY. AN ASSOCIATED
SURFACE COLD FRONT WILL ALSO WORK TOWARD THE REGION THURSDAY.
ROBUST MOISTURE TRANSPORT IS EXPECTED AHEAD OF THIS FRONT WITH
PWAT'S REACHING ABOVE THE NAEFS 97.5TH PERCENTILE BY THURSDAY
MORNING. TIMING DIFFERENCES REMAIN FOR THE FRONT ACROSS
DETERMINISTIC GUIDANCE, BUT SPREAD IS A BIT LESS IN LREF CLUSTER
ANALYSIS WITH EACH OF THE CLUSTERS NOW FAVORING AN
AFTERNOON/EVENING FRONTAL PASSAGE. SOME OF THE TIMING
DIFFERENCES LIKELY STEMS FROM THE PROGRESSION OF THE UPPER
TROUGH AND ITS INTERACTION WITH A CUT-OFF LOW THAT IS CURRENTLY
OFF THE WEST COAST. AS UPPER SUPPORT OVERSPREADS THE REGION LATE
WEDNESDAY INTO EARLY THURSDAY, SCATTERED SHOWERS AND STORMS
WILL BE POSSIBLE, LIKELY INCREASING IN COVERAGE THURSDAY
MORNING. THIS ACTIVITY COULD BRING PERIODS OF MODERATE TO HEAVY
RAIN AS FORECAST SOUNDINGS THURSDAY MORNING DEPICT LONG/SKINNY
ELEVATED CAPE PROFILES, A 35-40 KT LLJ, AND WARM CLOUD DEPTHS
EXCEEDING 11,000 FT. WITH THE ANTECEDENT DRY CONDITIONS, THE
OVERALL FLASH FLOODING RISK IS EXPECTED TO BE ON THE LOW SIDE AT
THE MOMENT. THE FRONT IS EXPECTED TO CLEAR LATE THURSDAY,
BRINGING AN END TO RAIN CHANCES FROM WEST TO EAST. BESIDES
SCATTERED TO WIDESPREAD RAIN, A TIGHTENING SURFACE PRESSURE
GRADIENT AND THE 35-40 KT LLJ COULD BRING BREEZY CONDITIONS
THURSDAY.
IN TERMS OF THE SEVERE WEATHER RISK, AS STATED IN PREVIOUS
DISCUSSIONS, THIS WILL BE HIGHLY DEPENDENT ON THE TIMING OF THE
FRONT AS PLENTY OF SHEAR SHOULD BE IN PLACE (0-6KM BULK SHEAR
NEAR 50-65KTS) WITH SOLID UPPER SUPPORT. AI/ML GUIDANCE
CONTINUES TO INDICATE AT LEAST A LOW END RISK AND THERE DOES
SEEM TO BE GREATER CONSENSUS ON MORE FAVORABLE TIMING ACROSS
LREF CLUSTERS WITH THIS PACKAGE. THE MAIN CONCERN WILL BE PRE
FRONTAL ACTIVITY THURSDAY MORNING. AS STATED ABOVE, FAVORABLE
DYNAMICS WILL BE IN PLACE FOR SCATTERED TO WIDESPREAD ACTIVITY
THURSDAY MORNING AND THUS DESPITE THE POTENTIAL FOR A SLOWER
MOVING FRONT, WIDESPREAD CLOUD COVER AND SHOWERS/WEAKER STORMS
MAY LIMIT DESTABILIZATION DURING THE AFTERNOON. THE MOST
FAVORABLE LOCATION FOR OVERLAPPING DYNAMICS, SHEAR, AND
INSTABILITY, CONTINUES TO LOOK JUST NORTH AND EAST OF THE FA,
PERHAPS STRETCHING DOWN TOWARD THE FAR EASTERN CWA, WHERE AROUND
75% OF EC ENSEMBLE MEMBERS SHOW MUCAPE NEAR 1000 J/KG
DEVELOPING THURSDAY AFTERNOON.
AVIATION /18Z SUNDAY THROUGH THURSDAY/
VFR CONDITIONS GENERALLY EXPECTED THROUGH THE 24HR FORECAST
PERIOD.
SATELLITE IMAGERY SHOWING MAINLY SUNNY SKIES ACROSS THE REGION
WITH SOME DIURNAL CUMULUS ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA. OUTSIDE OF THOSE FAIR WEATHER VFR CLOUDS WINDS
SHOULD BECOMING PREVAILING FROM THE WEST-SOUTHWEST AS THE AXIS
OF SURFACE HIGH PRESSURE GRADUALLY SLIDES EAST OF THE REGION.
WINDS SHOULD SUBSIDE WITH SUNSET ALTHOUGH THERE IS A 15-20 KNOT
LOW LEVEL JET WHICH MAY ALLOW FOR WINDS TO STAY A BIT MIXED AT
TIMES, WHICH COMBINED WITH A DRY AIR MASS WITH DEWPOINTS IN THE
40S OVERNIGHT SHOULD LIMIT FOG POTENTIAL. CANNOT COMPLETELY RULE
OUT SOME RIVER VALLEY FOG AT AGS/OGB BUT CONFIDENCE NOT HIGH
ENOUGH TO INCLUDE IN THIS FORECAST. WINDS SHOULD PICK UP BY 14Z
FROM THE SOUTHWEST AROUND 5 TO 8 KNOTS. THERE COULD BE A FEW
PASSING HIGH CLOUDS BUT NO IMPACT TO AVIATION EXPECTED.
EXTENDED AVIATION OUTLOOK...DRIER CONDITIONS ARE EXPECTED
THROUGH TUESDAY, THEN A MIDWEEK SYSTEM BRINGS A CHANCE FOR
RESTRICTIONS ONCE AGAIN.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...DH
AVIATION...23
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