673
FXUS62 KCAE 061808
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
208 PM EDT WED MAY 6 2026
WHAT HAS CHANGED
SLIGHT CHANGES TO THE OUTLOOK WITH THE INCOMING SYSTEM IN TERMS
OF QPF AND SEVERE CHANCES. AVIATION DISCUSSION UPDATED FOR 18Z
TAFS.
KEY MESSAGES
- 1. PERIODS OF MODERATE TO HEAVY RAIN EXPECTED THIS EVENING
INTO THURSDAY WHERE SEVERE WEATHER WILL BE POSSIBLE.
- 2. RAIN CHANCES PICK BACK UP LATE WEEK AND INTO THE WEEKEND.
DISCUSSION
KEY MESSAGE 1: PERIODS OF MODERATE TO HEAVY RAIN EXPECTED THIS
EVENING INTO THURSDAY WHERE SEVERE WEATHER WILL BE POSSIBLE.
OVERVIEW AS OF 1:40PM: BASED ON RECENT HAND SURFACE ANALYSIS
THE COLD FRONT IS NOW DRAPED ACROSS THE TENNESSEE VALLEY DOWN
INTO FAR NORTHERN MS/AL AND TOWARD NORTHWEST LA. THE BASE OF THE
UPPER TROUGH IS CONTINUING TO MOVE EASTWARD OUT OF THE SOUTHERN
PLAINS, BUT A 100+KT JET STREAK IS GRADUALLY SHIFTING TOWARD
THE TENNESSEE VALLEY WITH 50-65 KTS OF MID LEVEL FLOW CURRENTLY
OVERSPREADING THE SOUTHEAST AS SEEN IN THE LATEST CAE VAD
PROFILE. CONTINUING THE REMAINDER OF THE AFTERNOON AND INTO THE
EVENING, MOISTURE ADVECTION WILL CONTINUE TO INTENSIFY WHERE A
COUPLE SHOWERS OR A STORMS COULD MOVE INTO THE NORTHERN PART OF
THE CWA, WHERE A STORM ON THE STRONG TO SEVERE SIDE IS POSSIBLE.
LATE THIS EVENING AND OVERNIGHT IS WHEN COVERAGE IS EXPECTED TO
INCREASE, BRINGING THE POTENTIAL FOR HEAVY RAIN AND A COUPLE
STRONG TO MARGINALLY SEVERE STORMS. THE HEAVY RAIN RISK CARRIES
INTO THURSDAY WHERE ANOTHER ROUND OF STRONG TO MARGINALLY SEVERE
CONVECTION COULD BE POSSIBLE IN THE LATE MORNING TO AFTERNOON
HOURS. THESE PERIODS OF HEAVY RAIN BRING A FLASH FLOODING THREAT
LIMITED TO MAINLY URBAN AND FLOOD PRONE AREAS.
RAINFALL: THERE HAS NOT BEEN A SIGNIFICANT CHANGE TO THE
RAINFALL OUTLOOK. AS PWAT'S SURGE TO 1.75-1.90" AND A 35-50 KT
LLJ SETS UP LATER THIS EVENING WITH OVERSPREADING UPPER SUPPORT
AHEAD OF THE SURFACE FRONT, PERIODS OF HEAVY RAIN WILL BECOME
POSSIBLE. THIS RISK FOR HEAVY RAIN CARRIES INTO THURSDAY AS
MULTIPLE ROUNDS OF CONVECTION ARE EXPECTED. OVERALL, BLENDED
GUIDANCE MEAN AMOUNTS HAVE INCREASED A BIT TOWARD 0.75-1.25"
ACROSS THE AREA, WHICH SEEMS REASONABLE CONSIDERING THE NEAR
CLIMATOLOGICAL MAX PWAT'S/IVT AND POSSIBLE TRAINING OF
CONVECTION. DUE TO POSSIBLE TRAINING CONVECTION REFS AND HREF
LPMM QPF SHOWS POCKETS OF 2-3" OF RAINFALL MAINLY ACROSS THE
NORTHERN FA, POSSIBLY TOWARD THE CSRA. OVERALL, THE RISK FOR
WIDESPREAD FLASH FLOODING REMAINS LOW, BUT THE COMBINATION OF
POSSIBLE TRAINING THUNDERSTORMS AND VERY EFFICIENT RAIN RATES
WILL BRING THE RISK FOR ISOLATED SPOTS OF FLASH FLOODING MAINLY
FOR URBAN AND FLOOD PRONE AREAS.
SEVERE THREAT: THE POTENTIAL SEVERE THREAT REMAINS RATHER
COMPLEX AS THE FIRST ROUND OF CONVECTION IS EXPECTED THIS
EVENING INTO THE OVERNIGHT PERIOD BEFORE ANOTHER WILL BE
POSSIBLE LATE THURSDAY MORNING AND INTO THE AFTERNOON. THIS
SECOND ROUND WILL BE HIGHLY DEPENDENT ON THE PROGRESSION OF THE
FIRST. FOR THIS FIRST ROUND OF CONVECTION, RECENT CAM'S AND
PAINTBALLS FROM THE HREF AND REFS SHOW COVERAGE GRADUALLY
INCREASING ACROSS THE UPSTATE LATE THIS AFTERNOON AND EARLY THIS
EVENING BEFORE SHIFTING INTO THE NORTHERN FA LATER THIS
EVENING. SOME BREAKS IN CLOUD COVER ARE NOTED CURRENTLY IN
SATELLITE IMAGERY IN EASTERN GA AND NEAR THE WESTERN CWA BORDER,
WHICH MAY ALLOW SLIGHTLY GREATER INSTABILITY TO BUILD, BUT
STILL, INSTABILITY WITH THIS FIRST ROUND IS EXPECTED TO
GENERALLY BE LIMITED TO MUCAPE UNDER 800 J/KG. SOLID SHEAR IS
ALREADY MOVING IN PLACE PER THE CAE VAD PROFILE WITH NEAR 60 KTS
OF 0-6KM SHEAR AND 20 KTS OF 0-1KM SHEAR AS 60-70 KTS OF MID
LEVEL FLOW OVERSPREAD THE REGION. ONE CHANGE WITH THE OUTLOOK IS
IF A STORM CAN GET GOING BEFORE ANY INSTABILITY WANES
OVERNIGHT, THERE IS A NON-ZERO TORNADO RISK AS VAD 0-3KM SRH IS
ALREADY AROUND 100-150 M^2/S^2. THIS RISK IS MAINLY CONFINED TO
THE FAR NORTHERN FA. INSTABILITY SHOULD CONTINUE TO WANE
OVERNIGHT WITH WEAKENING LAPSE RATES SO THE MAIN RISK WITH ANY
MORE ORGANIZED SEGMENT/CLUSTER SHOULD BE HEAVY RAIN ALONG WITH
THE MARGINAL RISK FOR STRONG TO SEVERE WIND GUSTS.
AS HAS BEEN DISCUSSED, THIS SECOND ROUND OF POSSIBLE STRONG TO
SEVERE STORMS LATER THURSDAY MORNING INTO THE AFTERNOON WILL BE
HEAVILY DEPENDENT ON THIS FIRST ROUND. OVERALL, GUIDANCE IS
FAVORING THE PLUME OF DEEP MOISTURE SHIFTING EASTWARD THROUGH
THE AFTERNOON AND IS FAVORING LINGERING CLOUD COVER AND
SHOWER/STORM ACTIVITY INTO THE LATER PARTS OF THE MORNING,
KEEPING A MORE STABLE PROFILE. THIS IS NOTED IN RECENT BUFKIT
SOUNDINGS WHERE THE RAP PROFILE AT OGB DEPICTS SOME INHIBITION
AROUND 825 MB THAT LIKELY WOULD PREVENT ROBUST SURFACE BASED CI.
IF THE MORNING ACTIVITY CLEARS A BIT FASTER OR GREATER RECOVERY
IS SEEN THAN EXPECTED, THIS SECOND ROUND COULD BRING STORMS
WITH THE MAIN HAZARD OF STRONG TO SEVERE WINDS. IT IS WORTH
NOTING THE 12Z REFS DOES BRING FIXED LAYER STP VALUES UP TO
0.5-1.0 IN THE FAR EASTERN MIDLANDS AND PARTS OF THE SOUTHERN
CSRA AS STRONG SHEAR WILL LIKELY REMAIN IN PLACE, SHOWN IN
HODOGRAPHS WHERE SFC-1KM SRH IS UPWARDS OF 100-200 M^2/^2, SO A
NON-ZERO TORNADO RISK IS POSSIBLE HERE, BUT THERE IS VERY LOW
CONFIDENCE IN THIS RISK MATERIALIZING. OVERALL, TRENDS WITH THE
FIRST ROUND WILL NEED TO CONTINUE TO BE MONITORED TO GAIN MORE
CONFIDENCE IN ANY POTENTIAL SECOND ROUND OF CONVECTION.
KEY MESSAGE 2: RAIN CHANCES PICK BACK UP LATE WEEK AND INTO THE
WEEKEND
POP'S REMAIN LOW THROUGH FRIDAY AS A QUICK MOVING SURFACE HIGH
MOVES IN, BUT PWAT'S MOVE OVER AN INCH AGAIN INTO SATURDAY AND
EARLY NEXT WEEK. A SHORTWAVE MAY AID IN BRINGING SLIGHT CHANCE
TO CHANCE POP'S OVERNIGHT FRIDAY INTO SATURDAY MORNING, BUT THE
NEXT MAIN RAIN CHANCE SEEMS TO HOLD OFF UNTIL AT LEAST SUNDAY
AFTERNOON INTO MONDAY. GLOBAL MODELS STILL DIFFER SOME IN TIMING
FOR THIS LATE WEEKEND/EARLY WEEK SYSTEM, BUT THE SYNOPTIC
PATTERN FAVORS MORE RAIN CHANCES.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
VFR CONDITIONS TO START OFF THE PERIOD, THEN DETERIORATING INTO
MVFR LATE TONIGHT AS RAIN AND CLOUDS ASSOCIATED WITH A COLD
FRONT MOVES INTO THE REGION.
COLD FRONT AND ASSOCIATED RAINFALL WILL BE THE PRIMARY ISSUE
BEING DEALT WITH THROUGH THE NEXT 24 HOURS. THERE IS CURRENTLY A
FEW LIGHT SHOWERS/STORMS MOVING NORTH OF THE THE MIDLANDS
SITES, AND DO NOT ANTICIPATE ANY RESTRICTIONS REACHING ANY TAF
SITES FROM THAT ACTIVITY. INCREASING RAIN AND STORM POTENTIAL
WILL BE OCCURRING LATER THIS EVENING AND THEN THROUGH THE
MAJORITY OF THE OVERNIGHT HOURS. TIMING OF THE INITIAL ACTIVITY
APPEARS TO BE BETWEEN ABOUT 03Z-06Z, WITH SOME TIMING ISSUES
STILL BEING SHOWN. LEADING ACTIVITY MAY BE MORE ISOLATED TO
SCATTERED, AND HAVE LEANED MORE TOWARDS INTRODUCING VCSH TOWARDS
06Z. MORE WIDESPREAD RAIN AND EVEN ISOLATED STORMS BECOME
POSSIBLE BY 09Z, AND HAVE GONE AHEAD AND DROPPED CEILINGS AND
VISIBILITIES DOWN INTO MVFR/IFR IN PREDOMINANT RAIN AT THAT
TIME. SOME IMPROVEMENT IN VISIBILITIES POSSIBLE LATE THURSDAY
MORNING, BUT GUIDANCE IS FAIRLY HIGH IN REGARDS TO KEEPING
CEILINGS LOCKED IN BELOW 1KFT AND IFR AT LEAST INTO EARLY
AFTERNOON. AS FOR WINDS, THEY WILL CONTINUE TO BE GUSTY AT TIMES
THROUGH THE PERIOD, WITH SUSTAINED SPEEDS BETWEEN 7-12 KNOTS.
WIND DIRECTION REMAINS SOUTHERLY THROUGH TONIGHT, THEN BEGINS TO
TURN WESTERLY AS THE FRONT MOVES SOUTH OF EACH TAF SITE
THURSDAY MORNING.
EXTENDED AVIATION OUTLOOK...SYSTEM BRINGS A CHANCE FOR
RESTRICTIONS ONCE AGAIN WITH SHOWERS AND THUNDERSTORMS INTO
THURSDAY AFTERNOON. BREAK IN THE RAIN POSSIBLE ON FRIDAY.
ADDITIONAL RAIN CHANCES THIS WEEKEND.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
DISCUSSION...DH
AVIATION...CAL
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