856
FXUS62 KGSP 220217
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1017 PM EDT MON APR 21 2025
SYNOPSIS
A COLD FRONT WILL ARRIVE TONIGHT AND STALL ACROSS OUR AREA ON
TUESDAY, PROVIDING A FOCUS FOR MAINLY SCATTERED AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS. THIS PATTERN WILL REPEAT ITSELF
EACH AFTERNOON THROUGH MUCH OF THE WEEK AS CONDITIONS REMAIN WARM
AND BECOME INCREASINGLY HUMID.
NEAR TERM /THROUGH TUESDAY/
AS OF 1010 PM EDT MONDAY: WIND GUSTS HAVE DIMINISHED AND MOISTURE
OVER THE MOUNTAINS ASSOCIATED WITH THE COLD FRONT HAS FALLEN APART
OVER THE LAST FEW HOURS. CAMS DEPICT POPS WINDING DOWN OVER THE
MOUNTAINS FOR A FEW HOURS BEFORE PICKING BACK UP AGAIN OVERNIGHT SO
REFLECTED THIS TREND FOR THE EVENING UPDATE. OTHERWISE, HIGH- AND
MID-LEVEL CLOUD COVER WILL GRADUALLY THICKEN FROM WEST TO EAST
OVERNIGHT, ALLOWING LOWS TO END UP A SOLID 10+ DEGREES ABOVE NORMAL.
DRY CONDITIONS WILL PERSIST EAST OF THE MOUNTAINS OVERNIGHT.
TOMORROW, THE FRONT AND AN ASSOCIATED BAND OF RAINFALL WILL PUSH
FARTHER INTO THE FORECAST AREA. THE 00Z CYCLE OF OPERATIONAL
GUIDANCE DEPICTS PART OF THE BOUNDARY STALLING IN/NEAR THE
APPALACHIANS, AND THE NORTHERNMOST FRINGE SINKING SOUTH ACROSS I-40
IN THE AFTERNOON AND EVENING, ALMOST AKIN TO A BACKDOOR
FRONT...MEANING THAT ZONES ACROSS THE EASTERN UPSTATE AND SOUTHERN
PIEDMONT WILL BE THE LAST TO SEE THE ONSET OF RAIN...NOT UNTIL THE
LATE MORNING, AT LEAST. AS ACTIVITY SLOWLY PUSHES THROUGH THE ENTIRE
FORECAST AREA, A PLUME OF SBCAPE ON THE ORDER OF 600-1000 J/KG WILL
DEVELOP, AND WITH THE FRONT NOW IN PLACE TO ACT AS A TRIGGER, SOME
DIURNALLY-DRIVEN CONVECTION IS EXPECTED. FOR THE MOST PART, SEVERE
RISK LOOKS TO REMAIN LOW; HOWEVER, ALONG THE I-77 CORRIDOR, MUCH
STRONGER 500MB FLOW WITHIN AN UPPER JETLET MAY CONTRIBUTE TO A ZONE
OF HIGHER DEEP-LAYER SHEAR CAPABLE OF PRODUCING SOME LOOSELY-
ORGANIZED CELLS, PERHAPS EVEN A ROTATING UPDRAFT OR TWO. WHILE THE
LOW-LEVEL KINEMATICS DON'T LOOK FAVORABLE FOR ANY TORNADIC THREAT,
THERE'S A NONZERO CHANCE OF SOME LARGE HAIL AND/OR DAMAGING WINDS IF
STORMS BECOME STRONG TO SEVERE.
SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/
AS OF 110 PM EDT MONDAY: A SEASONABLY WARM AND MOIST AIR MASS WILL
REMAIN IN PLACE ACROSS THE AREA FOR WEDNESDAY AND THURSDAY. WEAK
IMPULSES IN THE WESTERLY MID LEVEL FLOW WILL ACT ON THIS MOISTURE
AND THE LINGERING FRONT IN THE AREA TO CREATE DIURNALLY ENHANCED
SHOWERS AND THUNDERSTORMS EACH DAY. POPS WILL BE PRETTY HIGH, BUT
AMOUNTS ARE EXPECTED TO BE LIGHT. IN FACT, NBM PROBABILITIES OF
GREATER THAN A HALF INCH OF RAIN PER 6 HOUR PERIOD AREA VERY LOW
SUPPORTING THE IDEA OF LIGHT AMOUNTS.
HIGH TEMPERATURES ARE EXPECTED TO BE 3-5 DEGREES ABOVE NORMAL ON
WEDNESDAY AND NEAR NORMAL ON THURSDAY.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
AS OF 120 PM EDT MONDAY: THE GENERAL PATTERN DESCRIBED IN THE SHORT
TERM SECTION SHOULD CONTINUE INTO FRIDAY AND SATURDAY. EXPECT
SCATTERED DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS EACH DAY. BY
SUNDAY, MID LEVEL RIDGING SHOULD BUILD ACROSS THE REGION LEADING TO
A DRYING TREND. HIGHS EACH DAY SHOULD BE NEAR NORMAL TO A FEW
DEGREES ABOVE NORMAL.
AVIATION /02Z TUESDAY THROUGH SATURDAY/
AT KCLT AND ELSEWHERE: SHRA ASSOCIATED WITH A COLD FRONT CONTINUES
PUSHING ACROSS THE NORTH CAROLINA MOUNTAINS AS OF 02Z BUT HAS BEEN
GRADUALLY FALLING APART THE LAST FEW HOURS. THIS ACTIVITY WILL
REMAIN OVER THE MOUNTAINS THROUGH TONIGHT SO KAVL WILL BE THE ONLY
TERMINAL TO SEE SHRA DEVELOP OVERNIGHT. LIGHT AND VARIABLE TO CALM
WIND SPEEDS WILL CONTINUE THROUGH DAYBREAK TUESDAY. WIND DIRECTION
WILL BE PRIMARILY S/SW EAST OF THE MOUNTAINS THROUGH DAYBREAK
TUESDAY. WINDS AT KAVL WILL START OUT SW'LY BEFORE TURNING NW'LY
AROUND 04-06Z. THE FRONT WILL STALL OVER THE AREA TUESDAY
AFTERNOON/EVENING ALLOWING ROUNDS FOR ROUNDS OF SHRA DURING THE
MORNING HOURS AND ROUNDS OF TSRA DURING THE AFTERNOON HOURS. SHRA
WILL DEVELOP BY TUESDAY MORNING FO TERMINALS EAST OF THE MOUNTAINS.
WENT WITH A COMBINATION OF PREVAILING SHRA AND PROB30S FOR SHRA
AND/OR TSRA ACROSS THE TERMINALS. CONFIDENCE ON TIMING, ESPECIALLY
ON TUESDAY, IS MODERATE AT BEST DUE TO SLIGHT COVERAGE AND TIMING
DIFFERENCES BETWEEN THE HIGH-RES GUIDANCE SOURCES. WINDS ON TUESDAY
WILL GENERALLY REMAIN LIGHT AND VRB OUTSIDE OF CONVECTION.
OUTLOOK: CONVECTIVE CHANCES WILL RAMP DOWN OR AT LEAST TRANSITION
BACK TO SHRA TUESDAY EVENING INTO TUESDAY NIGHT. MAINLY DIURNAL
SHOWERS/THUNDER AND ASSOCIATED RESTRICTIONS WILL CONTINUE EACH DAY
THROUGH THE END OF THE WEEK. PATCHY FOG AND/OR LOW STRATUS MAY
DEVELOP OVERNIGHT INTO DAYBREAK EACH MORNING WHERE HEAVIER
DOWNPOURS OCCURRED.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...AR/MPR
SHORT TERM...SCW
LONG TERM...SCW
AVIATION...AR
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