397
FXUS62 KCAE 060009
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
809 PM EDT TUE MAY 5 2026
WHAT HAS CHANGED
AVIATION DISCUSSION UPDATED FOR 00Z TAFS.
KEY MESSAGES
- 1. PERIODS OF MODERATE TO HEAVY RAIN ARE EXPECTED STARTING
OVERNIGHT WEDNESDAY, CONTINUING INTO THURSDAY WITH SEVERE
WEATHER POSSIBLE.
- 2. RAIN CHANCES PICK BACK UP LATE WEEK AND INTO THE WEEKEND.
DISCUSSION
KEY MESSAGE 1: PERIODS OF MODERATE TO HEAVY RAIN ARE EXPECTED
STARTING OVERNIGHT WEDNESDAY, CONTINUING INTO THURSDAY WITH
SEVERE WEATHER POSSIBLE.
OVERVIEW: A FRONT WILL BEGIN NEARING THE FA OVERNIGHT WEDNESDAY
INTO THURSDAY MORNING AS STRONG UPPER SUPPORT AND MOISTURE
ADVECTION OVERSPREADS THE REGION AS WELL. THIS IS EXPECTED TO
BRING MODERATE TO HEAVY RAINFALL ACROSS THE REGION STARTING AS
EARLY AS OVERNIGHT WEDNESDAY, CONTINUING INTO THE AFTERNOON
HOURS THURSDAY. AS HAS BEEN DISCUSSED PREVIOUSLY, A CONDITIONAL
THREAT FOR SEVERE WEATHER WILL EXIST WITH THIS SYSTEM. FAIRLY
BREEZY WINDS WILL BE POSSIBLE THROUGH THE DAY THURSDAY AS WELL
WHERE A LAKE WIND ADVISORY MAY BE NEEDED.
RAINFALL: ROBUST MOISTURE ADVECTION IS EXPECTED TO BEGIN
SHIFTING INTO THE AREA LATE WEDNESDAY INTO THURSDAY MORNING
AHEAD OF A FRONT AS A 35-45KT LLJ RAMPS UP AND PWAT'S REACH NEAR
1.75-1.90". ENHANCED CONVERGENCE AHEAD OF THE FRONT AND A
NEARING UPPER TROUGH SHOULD INCREASE RAIN CHANCES OVERNIGHT
WEDNESDAY INTO THURSDAY MORNING WHERE HEAVY RAINFALL WILL BE
POSSIBLE DUE TO THE AFOREMENTIONED FEATURES ALONG WITH DEEP WARM
CLOUD DEPTHS (OVER 11,000 FT) AND AT LEAST SOME WEAK
INSTABILITY. OVERALL, FORECAST RAIN AMOUNTS HAVE NOT SHIFTED TOO
MUCH WHERE A WIDESPREAD 0.50-1" SEEMS REASONABLE, BUT AS CAM
GUIDANCE REACHES FURTHER INTO THURSDAY, SPOTS OF HIGHER AMOUNTS
WILL BE POSSIBLE. THIS IS SEEN IN RECENT 12Z CAM'S WHERE SPOTS
OF 1-2.25" OF RAINFALL CAN BE SEEN, MAINLY WHERE ANY CONVECTION
TRACKS. THESE AMOUNTS ARE FURTHER SUPPORTED IN THE MOST RECENT
NBM 5.0 RUN WHERE 25TH PERCENTILE QPF AMOUNTS ARE AROUND
0.30-0.75", WITH THE 75TH PERCENTILE SHOWING AREAS OF 1-2.25".
PROBABILITIES FOR GREATER THAN 1" OF QPF THROUGH THURSDAY NIGHT
HAVE RISEN TOWARD 40-60%, MAINLY ALONG AND NORTH OF THE I-20
CORRIDOR. AS MENTIONED IN PREVIOUS DISCUSSIONS, THE OVERALL
FLASH FLOODING RISK IS LOW WITH ANTECEDENT DRY CONDITIONS, BUT
ISOLATED SPOTS OF FLASH FLOODING MAINLY IN URBAN OR FLOOD PRONE
AREAS WILL BE POSSIBLE WHERE CONVECTION MOVES OVER DUE TO HIGHER
RATES.
SEVERE THREAT: THE MAIN CHANGE IN SEVERE WEATHER CHANCES COMES
LATE WEDNESDAY INTO THURSDAY MORNING. AS THE UPPER TROUGH
PROGRESSES EASTWARD, ENHANCED MID LEVEL FLOW AROUND 50-65 KTS
SHOULD BEGIN OVERSPREADING THE FA WITH THE AFOREMENTIONED DEEP
MOISTURE MOVING INTO PLACE. THE MEAN 12Z HREF SOLUTION, ALONG
WITH MULTIPLE CAM'S (INCLUDING 12Z HRRR, NAM3KM, AND RRFS) SHOW
A BROKEN LINE OF CONVECTION SHIFTING INTO THE UPSTATE WEDNESDAY
EVENING BEFORE MOVING INTO THE FA LATE WEDNESDAY NIGHT,
CONTINUING SOUTHWARD INTO THE EARLY PARTS OF THURSDAY MORNING.
WITH ENHANCED MID LEVEL FLOW AND A STRENGTHENING LLJ MOVING IN,
STRONG DEEP LAYER SHEAR ON THE ORDER OF 50-65 KTS SHOULD SHIFT
IN PLACE OVERNIGHT. CONSIDERING THE TIME OF DAY, WEAK
INSTABILITY IS EXPECTED WITH MUCAPE GENERALLY UNDER 800 J/KG.
THEREFORE, A RATHER CONDITIONAL AND MARGINAL SEVERE THREAT IS
POSSIBLE LATE WEDNESDAY INTO THURSDAY MORNING, WHICH HAS BEEN
FURTHER SUPPORTED IN RECENT HRRR NEURAL NETWORK, CSU, AND NCAR
AI/ML GUIDANCE. OVERALL, THE MAIN RISK WILL BE HEAVY RAIN AS
DISCUSSED IN THE PREVIOUS SECTION, BUT IF A MORE ROBUST SEGMENT
OF CONVECTION CAN MAINTAIN ITSELF (MAINLY FROM THE STRONG
KINEMATICS), STRONG TO MARGINALLY SEVERE WIND GUSTS COULD BE
POSSIBLE MORE SO TOWARD THE NORTHERN FA. BEHIND THIS ACTIVITY
AND BEFORE THE FRONT MOVES THROUGH, REDEVELOPMENT OF CONVECTION
COULD BE POSSIBLE LATE THURSDAY MORNING INTO THE AFTERNOON AS
STRONG DEEP LAYER SHEAR REMAINS IN PLACE, BUT THIS THREAT IS
ALSO CONDITIONAL. A COUPLE OF FAILURE MODES EXIST IN THE
AFTERNOON HOWEVER WITH MODEL GUIDANCE FAVORING LINGERING CLOUD
COVER THROUGH THE DAY, DEEP MOISTURE GRADUALLY SHIFTING OUT OF
THE FA AND TOWARD THE COAST, AND THE BELT OF ENHANCED MID AND
UPPER FLOW SHIFTING NORTHWARD. IF INSTABILITY CAN BE REALIZED,
ANOTHER ROUND OF STRONG TO MARGINALLY SEVERE STORMS COULD BE
POSSIBLE, MAINLY TOWARD THE EASTERN MIDLANDS AND INTO THE PEE
DEE REGION.
KEY MESSAGE 2: RAIN CHANCES PICK BACK UP LATE WEEK AND INTO THE
WEEKEND
THERE CONTINUES TO BE A TREND TOWARD A MORE PROGRESSIVE PATTERN
THE REMAINDER OF THE FORECAST PERIOD ACROSS GLOBAL MODELS AND
ENSEMBLE GUIDANCE. THERE REMAINS UNCERTAINTY IN IF DRIER
CONDITIONS COULD WIN OUT IN THE FRIDAY AND SATURDAY TIME FRAME
WITH WEAK SHORTWAVES PASSING SO AT LEAST SLIGHT CHANCE POPS SEEM
REASONABLE DURING THIS PERIOD. THERE IS A BIT MORE CONSENSUS
THAT ANOTHER TROUGH WILL MOVE IN EARLY IN THE WEEK WITH DEEPER
MOISTURE RETURNING AND INCREASED RAIN CHANCES.
AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
VFR CONDITIONS EXPECTED TO CONTINUE OVERNIGHT AND INTO
WEDNESDAY.
A FEW SCATTERED MID-LEVEL CUMULUS CLOUDS THAT DEVELOPED THIS
AFTERNOON WILL CONTINUE TO DISSIPATE THIS EVENING. WINDS AND
GUSTS WILL GRADUALLY DIMINISH, THOUGH SPEEDS SHOULD REMAIN
BETWEEN 5-8 KNOTS OUT OF THE SOUTH. THERE MAY BE A BRIEF PERIOD
AROUND SUNRISE WHEN WINDS WILL BECOME LIGHT/VARIABLE WITH SPEEDS
DIPPING BELOW 5 KNOTS. OVERNIGHT, MOISTURE WILL GRADUALLY
INCREASE AS HIGH CIRRUS CLOUDS MOVE IN FROM THE WEST, LINGERING
THROUGH MUCH OF THE DAY OF WEDNESDAY. OVERALL, THE COMBINATION
OF INCREASING HIGH CLOUDS AND STEADY WINDS SHOULD HELP LIMIT FOG
FORMATION.
ON WEDNESDAY, BROKEN TO SCATTERED HIGH CLOUDS ARE EXPECTED TO
LINGER AS WINDS SHIFT TO SOUTHWESTERLY AT AROUND 10 KNOTS, WITH
GUSTS BETWEEN 15-20 KNOTS POSSIBLE. A DECAYING MCS SHOULD KEEP
SCATTERED SHOWERS TO OUR NORTH AND WEST EARLY IN THE DAY (NEAR
THE NC/SC BORDER). AT THIS TIME, RAINFALL ASSOCIATED WITH AN
APPROACHING SYSTEM IS EXPECTED TO HOLD OFF UNTIL AFTER 00Z,
CONTINUING INTO THE OVERNIGHT ON WEDNESDAY AND INTO THURSDAY.
EXTENDED AVIATION OUTLOOK...SYSTEM BRINGS A CHANCE FOR RESTRICTIONS
ONCE AGAIN WITH SHOWERS AND THUNDERSTORMS STARTING WEDNESDAY
EVENING INTO THURSDAY.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...DH
AVIATION...ND
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page