161
FXUS62 KGSP 300608
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
208 AM EDT SUN MAR 30 2025
SYNOPSIS
SHOWER AND THUNDERSTORM CHANCES INCREASE TODAY AS COLD FRONT
APPROACHES FROM THE WEST. THE FRONT WILL CROSS THE AREA MONDAY,
BRINGING THE POTENTIAL FOR STRONG TO SEVERE STORMS. DRY HIGH
PRESSURE RETURNS TUESDAY, THEN BECOMES ESTABLISHED OFF THE EAST
COAST, RESULTING IN WELL ABOVE NORMAL TEMPERATURES ACROSS THE
REGION LATE IN THE WEEK.
NEAR TERM /THROUGH TODAY/
AS OF 130 AM: EXPANSIVE HIGH PRESSURE REMAINS OVER THE WESTERN
ATLANTIC. MEANWHILE A SLOWLY STRENGTHENING SFC LOW AND ATTENDANT
SHORTWAVE WILL MOVE INTO THE UPPER MISSISSIPPI VALLEY, ON TRACK TO
PASS BY WELL TO OUR NORTHWEST. OUR CWA AND POINTS SOUTH WILL BE
MORE OR LESS IN THE WARM SECTOR OF THE LOW THROUGH THE NEAR TERM
PERIOD AND INTO MONDAY, FOR THAT MATTER. VERY LITTLE IN THE WAY
OF DYNAMIC FORCING WILL BE AT WORK IN OUR AREA THIS MORNING. WEAK
WARM UPGLIDE IS ONGOING NOW AND WILL AMPLIFY THROUGH THE MORNING;
MIDLEVEL CLOUD COVER ALREADY HAS DEVELOPED OVER OUR NW HALF,
AND SOME LIGHT HIGH-BASED SHOWERS ARE DEVELOPING OVER THE UPPER
TN VALLEY. THE BETTER MOISTURE/FORCING WILL REMAIN WEST OF THE
MOUNTAINS THIS MORNING BUT THOSE SHOWERS MAY TRACK INTO THE NC
COUNTIES BORDERING TN. IT IS MORE QUESTIONABLE WHETHER UPGLIDE
WILL BE STRONG ENOUGH OVER OUR WESTERN CWA TO SEE SHOWERS DEVELOP
IN SITU THIS MORNING. ISENTROPIC OMEGA FIELDS ARE NOT ALL THAT
IMPRESSIVE PARTLY ON ACCOUNT OF ONLY 20-25 KT WINDS AT 850 MB.
THE PRIMARY SOURCE OF LIFT THROUGH DAYBREAK WILL REMAIN MECHANICAL
LIFT AGAINST SOUTH-FACING RIDGES OF THE SW MOUNTAINS, NAMELY THE
BLUE RIDGE ESCARPMENT, MORE LIKELY TO RESULT IN DRIZZLE THAN TRUE
SHOWERS. MODELS HAVE SOMEWHAT SLOWED THE DEVELOPMENT OF SATURATED
PROFILES OVER THE CWA; CAMS ARE NO MORE RESPONSIVE WITH QPF THAN
THEY HAD BEEN LAST NIGHT IN THIS SETUP. LOWERED POPS OVER MUCH
OF THE WESTERN HALF OF THE CWA THIS MORNING, EXCEPT ALONG THE
RIDGES. LOW CLOUDS WILL INCREASE IN COVERAGE TOWARD DAYBREAK IN
THOSE AREAS, EXPANDING EASTWARD SUCH THAT TODAY WILL BE GENERALLY
CLOUDY.
INSTABILITY WILL DEVELOP DIURNALLY PERHAPS UP TO A COUPLE HUNDRED
JOULES OF SBCAPE. AS THE LOW MOVES TOWARD THE GREAT LAKES AND MAKES
ITS NEAREST PASS TO THE AREA, UPGLIDE APPEARS TO STRENGTHEN OVER
THE CWA, IN WHAT MIGHT BE TERMED A SECONDARY WARM FRONT. THESE
TWO ASPECTS APPEAR KEY FOR POPS TO INCREASE EAST OF THE MOUNTAINS.
MOST CAMS DEPICT SHOWERS DEVELOPING/TRACKING FROM SW TO NE ACROSS
THE CWA FROM AFTERNOON THRU EVENING. LIKELY WORDING IS INCLUDED IN
MOST AREAS WEST OF US 221 BY LATE AFTERNOON, AND TO 30-50% IN AREAS
EAST. MAX TEMPS COOLER THIS AFTERNOON ON ACCOUNT OF THE ABUNDANT
LOW CLOUD COVER AND REDUCED THICKNESSES OWING TO FALLING HEIGHTS.
SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/
KEY MESSAGES:
1) SHOWERS AND THUNDERSTORM CHANCES INCREASE SUNDAY NIGHT THROUGH
MONDAY.
2) STRONG TO SEVERE THUNDERSTORMS POSSIBLE MONDAY WITH A COLD FRONT
MOVING INTO THE AREA.
3) DRY WEATHER RETURNS TUESDAY WITH RAIN CHANCES INCREASING BY
MIDWEEK.
AS OF 150 PM SATURDAY: PICKING UP SUNDAY NIGHT, ONGOING SCATTERED
SHOWERS ARE POSSIBLE AHEAD OF A COLD FRONT CONTINUES ITS TREK TOWARD
THE CWA. AN AREA OF LOW PRESSURE OVER THE CENTRAL CONUS LIFTS NE AND
PROVIDES THE NEXT FORCING MECHANISM FOR STRONG TO POTENTIALLY SEVERE
WEATHER. STRONG SOUTHERLY SURFACE FLOW ADVECTS MOISTURE INTO THE
AREA AND BY SUNDAY NIGHT, INCREASING DEWPOINTS AND PRIMING THE
REGION FOR THUNDERSTORM CHANCES ON MONDAY. CURRENT GUIDANCE
INCREASES PWATS INTO THE 1-1.5 INCH RANGE AND BRINGS A DECENT SWATH
OF DPVA THROUGH WITH THE FRONT. BY MONDAY, THE COLD FRONT IS STILL
ON TRACK TO PUSH INTO THE CWA, BRINGING A RISK FOR SHOWERS AND
THUNDERSTORMS. HOWEVER, LATEST GUIDANCE HAS SLOWED THE FROPA A BIT
AND ARE NOT IN COMPLETE AGREEMENT WITH TIMING, BUT STILL HAVE THE
LINE MOVING THROUGH MONDAY MORNING INTO THE AFTERNOON. SHOULD THE
FRONT TAKE ITS TIME AND MOVE IN TOO EARLY, THIS COULD INHIBIT SEVERE
POTENTIAL WITH INSTABILITY BECOMING MORE ROBUST AND AVAILABLE
FURTHER TO THE EAST. GUIDANCE FROM NBM/GFS SHOWS A FEW HUNDRED
JOULES OF SBCAPE AND MODEST SHEAR OF 40-50KTS. MODELED SOUNDINGS IN
THE NC PIEDMONT DO SHOW A BIT OF CURVATURE AND 0-1KM SRH IN THE 100-
150 RANGE, SUGGESTING THAT THERE IS A NONZERO CHANCE FOR AN
ENVIRONMENT THAT COULD SUPPORT TORNADO DEVELOPMENT. AT THIS POINT,
THE STORM PREDICTION CENTER HAS HIGHLIGHTED THE AREA FOR POTENTIAL
SEVERE WEATHER, BUT THERE IS STILL UNCERTAINTY THIS FAR OUT. AS
HIGHLIGHTED YESTERDAY, A POSSIBLE LIMITATION TO THE SEVERE POTENTIAL
HERE, OTHER THAN THE EARLIER TIMING OF THE FRONT ARRIVAL, IS IF
SEVERE WEATHER DEVELOPS FURTHER SOUTH. THIS COULD INHIBIT MOISTURE
TRANSPORT AND DISRUPT THE NECESSARY INGREDIENTS FOR STRONGER
CONVECTION, LEAVING MORE SHOWERY STORMS BEHIND. ADDITIONALLY, QPF
RESPONSE CONTINUES TO BE LESS THAN IMPRESSIVE OVER THE SHORT PERIOD,
WHICH DOESN'T CONTRIBUTE MUCH IN THE WAY OF RELIEF FOR THE ONGOING
WILDFIRES. STORM TOTALS FROM SUNDAY THROUGH MONDAY NIGHT HAVE
ANYWHERE FROM 0.5 TO 1.5 INCHES, WITH THE STRONGEST SIGNAL ACROSS
THE FAR WESTERN NC MOUNTAINS AND NE GEORGIA COUNTIES. TRENDS ARE NOT
LOOKING BETTER AT THIS POINT, BUT WHERE RAIN IS NEEDED THE MOST IS
AT LEAST WHERE THE RAIN IS EXPECTED TO FALL. AFTER THE FROPA, HIGH
PRESSURE RETURNS AND SHUNTS RAIN CHANCES ON TUESDAY. TEMPERATURES
WILL REMAIN A TICK ABOVE NORMAL.
LONG TERM /WEDNESDAY THROUGH SATURDAY/
KEY MESSAGES
1) THE FORECAST HAS TRENDED DRIER IN THE MEDIUM RANGE, AS A STRONG
RIDGE BUILDS ACROSS THE SOUTHEAST
2) TEMPERATURES WARM TO WELL ABOVE NORMAL THROUGH THE PERIOD.
AS OF 140 AM SATURDAY: THE MEDIUM RANGE WILL BE DOMINATED BY A
STRONG UPPER RIDGE THAT WILL BUILD OVER THE SOUTHEAST THRU THE END
OF THE WEEK. THE 00Z GUIDANCE HAS TRENDED STRONGER WITH THE RIDGE,
AND THIS LOOKS TO SUPPRESS PRECIP CHANCES, DESPITE AN INCREASE IN
HUMIDITY WITHIN A SOUTHERLY TO SOUTHWESTERLY FLOW REGIME. WEDNESDAY
WILL HAVE THE BEST RAIN CHANCES, AS A WARM FRONT OF SORTS LIFTS
NORTH THRU THE AREA. THERE WILL BE A FEW HUNDRED J/KG OF CAPE TO
SUPPORT A FEW EMBEDDED THUNDERSTORMS IN WHATEVER CONVECTION MAY
DEVELOP, BUT THE SEVERE THREAT SHOULD BE LOW AS FORCING WON'T BE
STRONG. THE LATEST NBM STILL HAS SLGT CHC TO CHC POPS THURSDAY,
ESPECIALLY IN THE MOUNTAINS, BUT IF MODEL TRENDS HOLD, THESE WILL
LIKELY BE LOWERED IN LATER FORECASTS. FRIDAY AND SATURDAY LOOK
LARGELY DRY, AS THE UPPER HIGH WILL BE AT ITS STRONGEST AND DRIFTS
WESTWARD TOWARD FL. THE BIGGEST STORY WILL LIKELY BE THE UNUSUALLY
WARM TEMPS FOR EARLY APRIL. HIGHS MAY REACH THE UPPER 80S FRIDAY
IN THE I-85 CORRIDOR AND SOUTHEAST. LOWS WILL LIKELY BE IN THE
LOW TO MID 60S EACH NIGHT OUTSIDE THE MOUNTAINS. DEWPTS WILL CREEP
INTO THE 50S TO LOWER 60S, WHICH WILL HELP KEEP RH ABOVE CRITICAL
LEVELS FOR WILDFIRE RISK.
AVIATION /06Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: CLOUD DECK WITH BASES 050-120 ALREADY
PRESENT OVER THE TERMINALS, WITH A FEW LOWER VFR CLOUDS SCATTERED
UNDERNEATH, IN CONJUNCTION WITH WARM UPGLIDE OCCURRING ALOFT. A
FEW LIGHT RETURNS ARE SEEN ON RADAR OVER THE NC MOUNTAINS, PROBABLY
SPRINKLES WITH MINIMAL IMPACT, BUT SCT SHRA WILL BECOME INCREASINGLY
POSSIBLE OVER KAVL TOWARD DAYBREAK, AND BY LATE MORNING AT THE OTHER
TERMINALS, EXCEPTING KCLT. MVFR TO IFR CIGS ARE LIKELY TO DEVELOP
ALONG THE SOUTH-FACING RIDGES BEFORE DAYBREAK ALSO, AND THEN AT
KAVL AND THE SC SITES BY 11-15Z. A SECONDARY WARM FRONT ARRIVING
THIS AFTN NEAR KAND, AND PROGRESSING NE THROUGH THE EVENING, WILL
KICK OFF ANOTHER ROUND OF SHOWERS AND ISOLATED TO WIDELY SCATTERED
TSRA, WARRANTING PROB30 MENTION AT ALL SITES. TSRA MAY PRODUCE
IFR CIGS WHICH MAY NOT IMPROVE AFTERWARD. SHRA MAY DECREASE IN
COVERAGE AFTER 06Z BUT WIDESPREAD IFR IS EXPECTED TO REMAIN IN
PLACE THRU DAYBREAK MON. CONTINUED S TO SSW WINDS WITH 15-20 KT
GUSTS POSSIBLE THIS AFTN.
OUTLOOK: SHRA/TSRA AND ASSOCIATED RESTRICTIONS POSSIBLE ON MONDAY.
DRYING IS EXPECTED ON TUESDAY. SOME LIGHT PRECIP IS POSSIBLE BY
THURSDAY, BUT MORE LIKELY NOT UNTIL NEXT WEEKEND.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...ARK
NEAR TERM...WIMBERLEY
SHORT TERM...CP
LONG TERM...ARK
AVIATION...WIMBERLEY
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