346
FXUS62 KGSP 310615
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
215 AM EDT MON MAR 31 2025
SYNOPSIS
SHOWER AND THUNDERSTORM ARE EXPECTED TO CROSS THE AREA TODAY
AHEAD OF AN APPROACHING COLD FRONT. A FEW OF THESE STORMS COULD
BE SEVERE. THE FRONT PUSHES THRU TONIGHT, AND USHERS IN DRY HIGH
PRESSURE FOR TUESDAY. THE HIGH WILL SETTLE OFF THE SOUTHEAST
COAST AND KEEP WARM SOUTHERLY FLOW ACROSS THE REGION, RESULTING
IN WELL-ABOVE-NORMAL TEMPERATURES THROUGH THE END OF THE WEEK.
NEAR TERM /THROUGH TODAY/
AS OF 130 AM MON: MATURE SFC LOW WILL TRACK ACROSS SOUTHERN
ONTARIO/QUEBEC THRU THIS AFTERNOON, PULLING A COLD FRONT ACROSS
THE OHIO VALLEY OVER THE COURSE OF THE DAY. A PREFRONTAL LINE OF
CONVECTION EXTENDS FROM EASTERN KY TO NORTHEAST MS AT THIS HOUR.
THE 00Z CYCLE CAM DEPICTIONS ARE AS USUAL VERIFYING A LITTLE SLOW,
WITH EVEN THE 04Z HRRR SIMULATED REFLECTIVITY OUTPUT RUNNING ABOUT
AN HOUR BEHIND THE RADAR MOSAIC. ALTHOUGH INSTABILITY WILL DIMINISH
NOCTURNALLY, A 40+ KT LLJ AND MCV APPEAR TO STAY WITH THE LINE AND
WILL MAINTAIN FAVORABLE SHEAR PARAMETERS AS THE ACTIVITY PUSHES
ACROSS MOST OF TN; PORTIONS OF THE LINE ARE ALREADY BEGINNING TO
LOOK LESS ORGANIZED ON RADAR, AND CAM CONSENSUS SUGGESTS THIS
TREND TO CONTINUE IN EAST TN. HOWEVER, STILL WORTHY FOR 70-80%
POPS AND THUNDER CHANCES IN OUR SMOKIES/BALSAMS, WITH ARRIVAL AT
OUR BORDER AROUND 09-10Z (TAKING INTO ACCOUNT TIMING ERROR). MUCAPE
IS EXPECTED TO BE ONLY A FEW HUNDRED JOULES OVER OUR MOUNTAINS AT
THAT TIME, WHICH SUGGESTS ANY ORGANIZED SEGMENTS STILL HOLDING
TOGETHER ARE UNLIKELY TO SURVIVE EAST OF THE SPINE. A DECAYING
ARC OF SHOWERS HOWEVER COULD PUSH AS FAR EAST AS OUR FOOTHILLS
THROUGH LATE MORNING.
A JET STREAK IS PROGGED TO AMPLIFY OVER THE MID-MS VALLEY EARLY
THIS MORNING. HEIGHT FALLS AT THE BASE OF THE TROUGH OCCUR IN
THAT AREA, ALLOWING SBCAPE TO PERSIST THERE. A NEW LINEAR MCS IS
EXPECTED TO INITIATE AROUND 8-9 AM EST AND TRACK EASTWARD ACROSS
GA THRU MIDDAY. 1000-1500 J/KG OF SBCAPE ARE LIKELY TO DEVELOP
IN EASTERN GA AND THE UPSTATE FROM THEN INTO EARLY AFTN. THE MCS
POTENTIALLY WILL STRENGTHEN AND BE MAINTAINED THROUGH THOSE AREAS,
WITH ADDITIONAL DIURNALLY FORCED ACTIVITY DEVELOPING FURTHER NORTH.
MOST OF OUR PIEDMONT ZONES REMAIN UNDER AN ENHANCED RISK AREA PER
SPC, AND OUR MTNS ARE UNDER A SLIGHT RISK AREA. THE MAIN SEVERE
THREAT IS STILL DAMAGING STRAIGHT-LINE WINDS, WITH LARGE HAIL BEING
LESS LIKELY. IN ADDITION, BRIEF TORNADOES WILL BE POSSIBLE AS WELL,
ESPECIALLY OVER OUR EAST AND SOUTHEAST ZONES. THE LATEST CAMS STILL
DEPICT BETTER STORM ORGANIZATION TO OUR SOUTH AND EAST AS HAS BEEN
THE CASE FOR SEVERAL RUNS NOW. THE MAIN LINE OF SHOWERS AND STORMS
SHOULD MOVE EAST OF OUR CWA BY 22Z-00Z, WITH A SECONDARY LINE OF
SHOWERS MOVING OVER THE NC MTNS DURING THE EVENING HRS. THIS SE-
CONDARY LINE OF SHOWERS SHOULD FIZZLE OUT AS IT MOVES EAST OF THE
HIGHER TERRAIN TOMORROW NIGHT. HIGH TEMPS WILL TOP OUT ABOUT 5 TO
10 DEGREES ABOVE NORMAL.
SHORT TERM /TONIGHT THROUGH WEDNESDAY/
KEY MESSAGES:
1) DRY WEATHER RETURNS TUESDAY WITH RAIN CHANCES POSSIBLE BY MIDWEEK.
2) ABOVE NORMAL TEMPERATURES THURSDAY.
AS OF 155 PM SUNDAY: THE COLD FRONT CONTINUES TO MOVE THROUGH THE
AREA AND SHOULD BE CROSSING THE CWA MONDAY NIGHT. AFTER THE FROPA,
HIGH PRESSURE RETURNS AND SHUNTS RAIN CHANCES ON TUESDAY. THE
GENERAL SYNOPTIC FLOW TURNS MORE QUASI-ZONAL INTO MID WEEK BEFORE A
TROUGH BUILDS IN ACROSS THE ROCKIES AND AN AMPLIFYING RIDGE MOVES IN
FROM THE SOUTH. PREVIOUS FORECASTS HAD AN AREA OF LOW PRESSURE
FORMING OVER THE CENTRAL CONUS AND LIFTING NORTHWARD, TRAILING A
COLD FRONT ACROSS THE AREA. HOWEVER, RECENT GUIDANCE FROM THE
GFS/EURO BOTH SHOW A STOUT RIDGE EXPANDING AND PERSISTING OVER THE
AREA FROM ABOUT MIDWEEK ONWARD. THIS IS TRENDING RAINFALL POTENTIAL
EVEN DRIER AS THE AREA OF BETTER LIFT/CONVERGENCE IS NOW OFF THE NW
OF THE CWA. THIS DOES LOWER QPF RESPONSE AND POPS DOWN INTO THE
SLIGHT CHANCE RANGE AS CONFIDENCE IS DECREASING FOR RAIN POTENTIAL.
THESE HEIGHT RISES COULD SHUNT PRECIP CHANCES AND BRING TEMPERATURES
WELL ABOVE NORMAL THROUGH THE SHORT TERM AND INTO THE NEXT. ONE
POSITIVE NOTE IS SOUTHERLY WINDS RETURN WEDNESDAY NIGHT AND ADVECT
MORE MOISTURE, KEEPING RH VALUES WELL ABOVE ANY CRITICAL LEVELS.
TUESDAY LOOKS TO BE THE DRIEST DAY WITH RH VALUES IN THE 25%-35%
RANGE, BUT IMPROVING ONWARD.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
KEY MESSAGES
1) THE FORECAST HAS TRENDED DRIER, AS A STRONG RIDGE BUILDS ACROSS
THE SOUTHEAST
2) TEMPERATURES WARM TO WELL ABOVE NORMAL THROUGH THE PERIOD.
AS OF 200 PM SUNDAY: AS WAS THE CASE IN THE SHORT TERM, GUIDANCE
FROM THE GFS/EURO CONTINUE TO TREND TOWARD AN AMPLIFYING RIDGE OVER
THE SOUTHEAST THROUGH MOST OF THE FORECAST PERIOD. SOUTHERLY FLOW
REMAINS DOMINATE DURING THE TIME, SO MOISTURE REMAINS IN THE AREA.
THE RIDGE AXIS PUSHES WEST A BIT, SHUNTING ONCE AGAIN MOST OF THE
BETTER PRECIPITATION CHANCES OFF TO THE NORTH. BY DAY 7, MODELS HINT
AT THE RIDGE STARTING TO WEAKEN, BRINGING BACK RAIN CHANCES, BUT
THIS IS HIGHLY UNCERTAIN SINCE IT'S A WEEK AWAY. OVERALL, GUIDANCE
CONTINUES TO TREND DRIER FOR THE AREA, KEEPING NEEDED RAINFALL AWAY
ONCE AGAIN. GIVEN THE MOISTURE IN THE REGION, WON'T RULE OUT A FEW
SCATTERED SHOWERS, SO WILL KEEP SLIGHT CHANCE POPS FOR MOST OF THE
EXTENDED. ADDITIONALLY, CONFIDENCE IS INCREASING THAT THE AREA COULD
HAVE TEMPERATURES IN THE UPPER 80S TOWARD THE END OF THE FORECAST
PERIOD DEPENDING ON THE STRENGTH OF THE BUILDING RIDGE. OVERALL,
EXPECT WELL-ABOVE NORMAL TEMPERATURES AND LITTLE RAINFALL.
AVIATION /06Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: MOSTLY IFR CIGS OVER THE PIEDMONT AT
ISSUANCE TIME, WITH A FEW POCKETS OF MVFR COMING AND GOING
WITHIN. NOT EXPECTING MUCH CHANGE IN THIS DECK THROUGH DAYBREAK,
ALTHOUGH IFR IS LIKELY TO BECOME MORE COMMON AND LIFR DEVELOPING IN
SPOTS. KAVL WILL SEE PREDOMINANTLY MVFR. -DZ OR A FEW -SHRA WILL
BE POSSIBLE PRIOR TO DAYBREAK BUT WITH LITTLE ADDITIONAL IMPACT
BEYOND THE RESTRICTIVE CIGS. AHEAD OF AN APPROACHING COLD FRONT,
A LINE OF TSRA WILL MOVE ACROSS TN THRU ABOUT 09Z THIS MORNING,
THEN LIKELY PUSHING INTO THE NC MOUNTAINS AND WEAKENING. PROB30
AT KAVL AND TEMPO AT KHKY FOR THIS ACTIVITY. CIGS WILL SLOWLY LIFT
THRU THE EARLY DAY. A SECOND BAND OF TSRA WILL DEVELOP IN AL/GA BY
LATE MORNING AND WILL PROPAGATE INTO WESTERN NC/SC BY EARLY AFTN,
PROMPTING TEMPOS AT ALL SITES FOR TSRA AND MVFR TO IFR VSBY/CIGS. A
RISK OF DAMAGING WINDS AND POSSIBLY 1-1.5" HAIL WILL ACCOMPANY THESE
STORMS. A FEW SHRA MAY REDEVELOP FOLLOWING THE TSRA WITH LESSER
IMPACTS. WINDS WILL BE GUSTY 15-25 KT FROM THE SSW TO SW UNTIL EARLY
EVENING, THEN SHIFT TO NW WITH PASSAGE OF FRONT. REDEVELOPMENT OF
MVFR CIG CAN'T BE RULED OUT AT KAVL AFTER 06Z.
OUTLOOK: DRYING AND VFR EXPECTED ON TUESDAY. SMALL CHANCE OF
SHOWERS AND ASSOCIATED RESTRICTIONS WEDNESDAY AND THURSDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...ARK
NEAR TERM...PM/WIMBERLEY
SHORT TERM...CP
LONG TERM...CP
AVIATION...WIMBERLEY
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