024
FXUS62 KCAE 211025
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
625 AM EDT TUE JUL 21 2026
WHAT HAS CHANGED
AVIATION DISCUSSION UPDATED FOR 12Z TAFS.
KEY MESSAGES
- 1. HOT AND HUMID TODAY WITH ISOLATED CHANCE FOR THUNDERSTORMS
THIS AFTERNOON/EVENING.
- 2. A FRONT NEARS THE AREA LATE TOMORROW AND THURSDAY,
BRINGING SCATTERED TO WIDESPREAD RAIN/STORM CHANCES, MAINLY
THURSDAY. SEVERE WEATHER AND HEAVY RAINFALL COULD BE POSSIBLE
WITH THIS. ACTIVE WEATHER PERSIST INTO THE LATE WEEK.
DISCUSSION
KEY MESSAGE 1: HOT AND HUMID TODAY WITH ISOLATED CHANCE FOR
THUNDERSTORMS THIS AFTERNOON/EVENING.
SLIGHTLY "DRIER" AIR IS EXPECTED TO ADVECT INTO THE AREA TODAY.
THIS AREA OF LOWER PWAT'S (1.60-1.80") CAN BE SEEN IN THE
FLORIDA PENINSULA AND SHOULD ADVECT INTO THE REGION DUE TO
SOUTHERLY/SOUTHWESTERLY LOW-LEVEL FLOW ON THE EASTERN PERIPHERY
OF WHAT IS NOW TS BERTHA. LITTLE IN WAY OF FORCING FOR
CONVECTION IS EXPECTED TODAY OUTSIDE OF POTENTIALLY REACHING
CONVECTIVE TEMPERATURES BETWEEN 95-97F. DUE TO THIS, ANY
CONVECTION THIS AFTERNOON IS EXPECTED TO BE FAIRLY ISOLATED AND
OUR TYPICAL SUMMERTIME PULSE VARIETY. AS ALWAYS WITH THESE PULSE
STORMS, DOWNPOURS AND LOCALLY STRONG WIND GUSTS COULD BE
POSSIBLE. DESPITE THE SLIGHTLY DRIER AIR, DEWPOINTS SHOULD STILL
BE IN THE UPPER 60S TO LOW 70S WITH AFTERNOON HIGHS IN THE MID
TO UPPER 90S. THIS SHOULD BRING ANOTHER DAY WITH HEAT INDICES
BELOW ADVISORY CRITERIA, BUT STILL BETWEEN 100-105F.
KEY MESSAGE 2: A FRONT NEARS THE AREA LATE TOMORROW AND
THURSDAY, BRINGING SCATTERED TO WIDESPREAD RAIN/STORM CHANCES,
MAINLY THURSDAY. SEVERE WEATHER AND HEAVY RAINFALL COULD BE
POSSIBLE WITH THIS. ACTIVE WEATHER PERSIST INTO THE LATE WEEK.
THE OVERALL SYNOPTIC PATTERN AND OUTLOOK HAS NOT CHANGED
SIGNIFICANTLY BUT AS HIGH-RES ENSEMBLES REACH TOWARD WEDNESDAY,
A FEW MORE DETAILS ARE STARTING TO GET SORTED OUT. THE MAIN
CHANGE SEEN IN THE 00Z HREF AND REFS IS SLIGHTLY LATER TIMING OF
WHEN THE FRONT NEARS THE FA ALONG WITH UPPER SUPPORT FROM THE
TROUGH SHIFTING INTO THE EASTERN US. THIS HAS LED TO WEDNESDAY
TRENDING SLIGHTLY WARMER WITH ISOLATED TO WIDELY SCATTERED
CONVECTION POSSIBLE BY THE LATE AFTERNOON BEFORE MORE SCATTERED
TO WIDESPREAD CHANCES MOVE IN OVERNIGHT THROUGH THURSDAY. AI/ML
GUIDANCE CONTINUES TO HINT AT THE POTENTIAL FOR STRONGER
CONVECTION IN THIS WINDOW, WHICH IS REASONABLE CONSIDERING DEEP
LAYER SHEAR WILL BE INCREASING TO NEAR 30 KTS WITH A 30-35 KT
LLJ DEVELOPING LATE WEDNESDAY. THE MAIN CAVEAT HERE IS THE LATER
TIMING ALLOWS LESS OVERLAP OF FORCING WITH WANING INSTABILITY,
SO IF THIS LATER TREND CONTINUES, THE SEVERE RISK COULD CONTINUE
TO DECREASE. AS THE FRONT STALLS OUT IN THE CWA DURING THE DAY
THURSDAY, ANOTHER CHANCE FOR STRONGER CONVECTION COULD
MATERIALIZE. OUTSIDE OF THIS, THE MAIN HAZARD SEEMS TO BE THE
HEAVY RAINFALL POTENTIAL STARTING LATE WEDNESDAY, CONTINUING
THROUGH THE DAY THURSDAY. SKINNY CAPE PROFILES OVERLAPPING WITH
THE AFOREMENTIONED LLJ AND PWAT'S OVER 2" SHOULD AID IN CREATING
EFFICIENT RAIN RATES AND POSSIBLE TRAINING OF CONVECTION ALONG
THE FRONTAL BOUNDARY. NBM PROBABILITIES FOR GREATER THAN 1" OF
QPF THROUGH THURSDAY NIGHT HAVE RISEN TO 50-70% ALONG/EAST OF
THE I-26 CORRIDOR. THESE PROBABILITIES ARE LIKELY A BIT SKEWED A
BIT DUE TO THE MORE AGGRESSIVE ECMWF SOLUTION, BUT THE
ENVIRONMENT SUPPORTS THIS HEAVY RAIN SETUP AND THE EC EFI SHOWS
VALUES OF 0.7-0.8 WITH A SHIFT- OF-TAILS OF 1-2 OVER THE AREA,
FURTHER SUPPORTING THE POTENTIAL FOR ANOMALOUS RAINFALL.
THE FRONTAL BOUNDARY IS SHOWN IN GLOBAL MODELS RESIDING IN THE
FA MOST OF FRIDAY AS ANOTHER SHORTWAVE PUSHES IN, LIKELY
BRINGING ANOTHER DAY WITH SCATTERED TO WIDESPREAD RAIN CHANCES.
HEADING INTO THE WEEKEND, THERE IS A BIT MORE UNCERTAINTY IN THE
EXACT PROGRESSION OF THE FRONT, BUT A TROUGHING PATTERN IS
EXPECTED TO CONTINUE WITH A SERIES OF SHORTWAVES TRAINING INTO
THE FA FROM THE NORTHWEST. DUE TO THIS, AN ACTIVE/WET PATTERN
SHOULD PERSIST AT LEAST INTO THE START OF THE WEEKEND.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
BRIEF MVFR CEILINGS POSSIBLE THIS MORNING BUT OTHERWISE VFR
CONDITIONS EXPECTED TO CONTINUE.
SATELLITE OBSERVATIONS EARLY THIS MORNING SHOW PATCHY LOW
CLOUDS, GENERALLY BETWEEN 1500 AND 2500 FEET. THESE MAY CAUSE
BRIEF MVFR CEILING RESTRICTIONS THIS MORNING WITH VFR CONDITIONS
EXPECTED TO PERSIST BY MID TO LATE MORNING. WINDS REMAIN OUT OF
THE SOUTH WITH GUSTS INCREASING BETWEEN 15 TO 20 KNOTS LATE
MORNING INTO THE AFTERNOON WITH CUMULUS DEVELOPING AROUND 6KFT.
ONCE AGAIN, CONVECTION IS EXPECTED TO BE LIMITED TODAY WITH
HIGHEST POTENTIAL NEAR 00Z. WITH UNCERTAINTY IN IMPACTS TO
TERMINALS, HAVE LEFT OUT THE MENTION OF TSRA WITH THIS ISSUANCE.
GUSTS SUBSIDE WITH CUMULUS DISSIPATING TONIGHT.
EXTENDED AVIATION OUTLOOK...POTENTIAL FOR RESTRICTIONS FROM
SHOWERS AND THUNDERSTORMS CONTINUES WITH THE THREAT INCREASING
FOR THE MID TO LATE WEEK PERIOD.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...DH
AVIATION...96
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