397
FXUS62 KGSP 201033
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
633 AM EDT WED MAY 20 2026
WHAT HAS CHANGED
THE AVIATION DISCUSSION WAS UPDATED TO REFLECT THE 12Z TAF ISSUANCE.
KEY MESSAGES
1. A COLD FRONT WILL APPROACH THE AREA TODAY AND THEN STALL
NEARBY THROUGH THE WEEKEND, RESULTING IN COOLER AND WETTER WEATHER
THROUGH MEMORIAL DAY WEEKEND. THE THREAT FOR SEVERE THUNDERSTORMS
AND EXCESSIVE RAIN APPEARS TO BE LOW AT THIS TIME.
DISCUSSION
KEY MESSAGE 1: A COLD FRONT WILL APPROACH THE AREA TODAY AND THEN
STALL NEARBY THROUGH THE WEEKEND, RESULTING IN COOLER AND WETTER
WEATHER THROUGH MEMORIAL DAY WEEKEND. THE THREAT FOR SEVERE
THUNDERSTORMS AND EXCESSIVE RAIN APPEARS TO BE LOW AT THIS TIME.
ONE MORE SEASONALLY HOT DAY TODAY, THEN THE FORECAST GETS MORE
UNCERTAIN. THE SITUATION TODAY LOOKS SIMILAR TO YESTERDAY AS THE
WESTERN CAROLINAS ARE UNDER A COL REGION OF SORTS, RESULTING FROM
THE TUTT LOW NORTH OF THE BAHAMAS SUPERIMPOSED ON THE OLD UPPER
RIDGE DEAMPLIFYING OFF THE EAST COAST. MEANWHILE, A COLD FRONTAL
BOUNDARY WILL BE MAKING SLOW PROGRESS EAST OF THE OH VALLEY AND
OVER THE TN VALLEY REGION. THE UPSHOT IS THAT WE WON'T HAVE MUCH
IN THE WAY OF SUPPORT FOR DEEP CONVECTION OR BUOYANCY THROUGH
TONIGHT, AT LEAST NOT EAST OF THE MTNS. THERE WILL PROBABLY BE
ENOUGH DIFFERENTIAL HEATING OVER THE MTNS TO SUPPORT SOME SHOWER
ACTIVITY, ESPECIALLY IN LIGHT OF THE ISOLATED DEVELOPMENT YESTERDAY,
SO A CHANCE WAS KEPT THERE. THE SHOWERS SHOULD TAPER OFF WITHIN A
FEW HOURS OF SUNSET. PLENTY OF SUN AND A LACK OF CONVECTION SHOULD
ALLOW US TO GET ABOUT TEN DEGREES ABOVE NORMAL AGAIN, BUT THE AIR
MASS REMAINS DRY ENOUGH TO PREVENT ANY REAL HEAT PROBLEMS.
THURSDAY SHOULD BE THE TRANSITION DAY AS THE GUIDANCE MOVES THE
OLD COLD FRONT INTO OUR REGION EVEN AS MID/UPPER RIDGING TRIES
TO REBUILD OVERHEAD. GUIDANCE INDICATES THAT SOUTHWEST FLOW ALOFT
WILL BECOME BETTER ESTABLISHED WHICH SHOULD HELP PROVIDE MORE FUEL
WHILE THE FRONTAL BOUNDARY PROVIDES MORE FOCUS. TEMPERATURES ARE A
CONCERN. HIGHS ARE FORECAST TO BE 5-10 DEGREES ABOVE NORMAL AGAIN
BECAUSE THE CONVECTION DOESN'T REALLY GET GOING UNTIL MID/LATE
AFTERNOON, BUT IF THAT WERE TO BEGIN BY MIDDAY, TEMPS MIGHT NOT
GET AS WARM AS EXPECTED. THE OVERALL RISK FOR SEVERE THUNDERSTORMS
AND HEAVY RAIN APPEARS TO BE RELATIVELY LOW, BUT THURSDAY PROBABLY
HAS THE BEST SHOT OF ANY DAY UPCOMING BECAUSE OF BETTER SFC-BASED
CAPE WHICH TOPS OUT AROUND 2500 J/KG AND SOME WEAK SOUTHWESTERLY
SHEAR. BECAUSE OF THE CONVECTIVE NATURE OF THE EXPECTED PRECIP,
SOME WILL WIN AND MANY WILL LOSE.
THE EXPECTATION IS THAT THE BOUNDARY WILL BE PUSHED SOUTH ACROSS
THE FCST AREA THURSDAY NIGHT BY HIGH PRESSURE MOVING ACROSS THE
GREAT LAKES. THIS TRANSITORY SFC HIGH TO OUR NORTH WILL SUPPORT
A COLD AIR DAMMING WEDGE FOR AT LEAST FRIDAY, DROPPING OUR TEMPS
TEN DEGREES OR MORE. THE CAD SIGNAL APPEARS STRONGER WITH THIS
CYCLE. SOME OF THE GUIDANCE HAS TEMPS STRUGGLING TO GET OUT OF THE
60S IN THE TYPICAL WEDGE AREAS AND THAT COULD HAPPEN IF SUFFICIENT
LOW LEVEL ISENTROPIC LIFT DEVELOPS. NOTE THAT SEVERAL OF THE MODELS
DO JUST THAT AND THE RAW MODEL TEMPS SUPPORT UNDERCUTTING THE NBM
SUBSTANTIALLY, SO THE EXPECTATION IS THAT OUR HIGH TEMP FOR FRIDAY
WILL DRIFT COOLER. PRECIP PROBS CLIMB INTO THE LIKELY/CATEGORICAL
RANGES AND SEEM TO STAY THERE THROUGH THE HOLIDAY WEEKEND AND
DON'T IMPROVE UNTIL THE MIDDLE OF NEXT WEEK. THE LATEST GUIDANCE
SUPPORTS THIS IDEA WITH A PROLONGED MOISTURE FLOW FROM THE GULF
BECAUSE OF A FAVORABLE MEAN TROF/RIDGE PATTERN. EXPECTATIONS SHOULD
BE MANAGED AT THIS POINT, BUT IF THE MODELS STICK WITH THIS IDEA,
WE COULD ACTUALLY SEE ENOUGH RAIN TO BE BENEFICIAL ACROSS SOME
PARTS OF THE REGION OVER THE FIVE DAY PERIOD. THE QPF HAS BEEN
INCREASED. AT ANY RATE, THE DROUGHT SHOULDN'T GET ANY WORSE.
AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
AT KCLT AND ELSEWHERE: VFR SHOULD PREVAIL AT ALL TERMINALS THROUGH
THE PERIOD. THE ONLY CONCERN WOULD BE SCATTERED SHOWERS/STORMS
THAT MAY DEVELOP OVER THE MOUNTAINS THIS AFTERNOON, THOUGH THE
LATEST MODEL GUIDANCE KEEPS STORMS MORE ISOLATED THAN WE HAVE IN
OUR FORECAST. WILL MAINTAIN A PROB30 AT KAVL ANYWAY UNTIL THERE
IS MORE CONFIDENCE IN IT NOT HAPPENING. OTHERWISE, LIGHT/VARIABLE
WIND THROUGH SUNRISE WILL BECOME LIGHT SW TO S ONCE AGAIN, AND A
FEW STRATOCU ARE EXPECTED. WEDNESDAY NIGHT SHOULD BE QUIET AGAIN,
BUT CLOUDS WILL START TO INCREASE LATE.
OUTLOOK: AN APPROACHING FRONT AND INCREASING MOISTURE WILL BRING
A MORE ACTIVE PATTERN FOR MAINLY AFTERNOON AND EVENING SHOWERS
AND THUNDERSTORMS BEGINNING THURSDAY AFTERNOON AND THEN CONTINUING
THROUGH THE END OF THE WEEK. COLD-AIR DAMMING MAY PRODUCE WIDESPREAD
MVFR TO IFR CIGS THRU THE DAY FRIDAY. THE POTENTIAL FOR OVERNIGHT
FOG/LOW CLOUDS WILL INCREASE THROUGH THE PERIOD AS WELL.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
PM
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page