819
FXUS62 KGSP 032333
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
733 PM EDT FRI APR 3 2026
WHAT HAS CHANGED
ADJUSTED TONIGHT'S FORECAST BASED ON LATEST TRENDS AND MESOSCALE
GUIDANCE.
UPDATED FOR THE THE 00Z AVIATION DISCUSSION.
KEY MESSAGES
1. WELL ABOVE NORMAL AND HUMID WITH ISOLATED TO SCATTERED DIURNAL
SHOWERS AND THUNDERSTORMS POSSIBLE THROUGH SATURDAY.
2. THE PASSAGE OF A COLD FRONT SUNDAY WILL BRING THE BEST CHANCE
FOR RAINFALL AT ANY TIME OVER THE NEXT WEEK. THE RISK OF FLOODING
RAIN OR SEVERE WEATHER APPEARS TO BE LOW.
3. COLD AIR COULD BRING FROST OR A FREEZE TO PARTS OF THE NC
MOUNTAINS, FOOTHILLS, AND NORTHWEST PIEDMONT EARLY NEXT WEEK. THE
MOST LIKELY TIME WOULD BE TUESDAY NIGHT. PROTECTION OF SENSITIVE
VEGETATION MIGHT BE NECESSARY.
DISCUSSION
KEY MESSAGE 1: WELL ABOVE NORMAL AND HUMID WITH ISOLATED TO SCATTERED
DIURNAL SHOWERS AND THUNDERSTORMS POSSIBLE THROUGH SATURDAY.
BERMUDA HIGH LINGERS OVER THE REGION THROUGH SATURDAY KEEPING THE
SUMMERLIKE PATTERN AROUND. WELL ABOVE NORMAL AND HUMID CONDITIONS
WILL LINGER OVER THE REGION THANKS TO SOUTHERLY FLOW AND DEWPOINTS
RANGING FROM THE 50S TO 60S. HIGHS EACH AFTERNOON WILL END UP 10-13
DEGREES ABOVE NORMAL WITH LOWS TONIGHT ENDING UP AROUND 20 DEGREES
ABOVE NORMAL. SHOWER AND THUNDERSTORM ACTIVITY WILL REMAIN ISOLATED
THIS EVENING, BUT INCREASING LOW LEVEL MOISTURE AND UPSLOPE FLOW
WILL LEAD TO SHOWERS DEVELOPING ALONG AND NEAR THE BLUE RIDGE SOUTH
INTO THE UPPER SAVANNAH RIVER VALLEY. THESE SHOWERS SHOULD DISSIPATE
THROUGH THE MORNING. CONVECTIVE CHANCES MAY INCREASE ON SATURDAY BUT
CONFIDENCE IS LOW AS THE 12Z CAMS ARE STILL NOT IN AGREEMENT
REGRADING COVERAGE OF CONVECTION TOMORROW AFTERNOON AND EVENING. THE
12Z HRRR SHOWS SCATTERED TO WIDESPREAD CONVECTION DEVELOPING ACROSS
MUCH OF THE GSP CWA WHILE THE 12Z NAMNEST SHOWS MOSTLY DRY
CONDITIONS OUTSIDE ISOLATED CONVECTION ACROSS THE MOUNTAINS DURING
PEAK HEATING TOMORROW. WITH CONFIDENCE ON POPS REMAINING LOW, CAPPED
POPS TO 65% WEST OF I-77 AND 50% ALONG/NEAR THE I-77 CORRIDOR.
SEVERE STORMS ARE NOT EXPECTED THANKS TO VERY LOW SHEAR IN PLACE,
BUT A FEW STRONG, SUB-SEVERE STORMS CANNOT BE ENTIRELY RULED OUT
DURING PEAK HEATING HOURS SATURDAY.
KEY MESSAGE 2: THE PASSAGE OF A COLD FRONT SUNDAY WILL BRING THE
BEST CHANCE FOR RAINFALL AT ANY TIME OVER THE NEXT WEEK. THE RISK
OF FLOODING RAIN OR SEVERE WEATHER APPEARS TO BE LOW.
MATURE MIDLATITUDE CYCLONE WILL TRACK NORTH OF THE GREAT LAKES LATE
SATURDAY, THEN INTO NORTHERN QUEBEC SUNDAY. TRAILING COLD FRONT
WILL ADVANCE ACROSS THE SOUTHEAST. THOUGH CONVECTION GENERALLY
WILL WANE NOCTURNALLY SATURDAY EVENING, NAM AND HRRR SUGGEST
SOME NEW DEVELOPMENT MAY OCCUR IN PREFRONTAL CONVERGENCE ZONE
OVER NE GA AND THE SOUTHWESTERNMOST NC MOUNTAINS; THUS RETAINED
HIGHER POPS IN THE EVENING THAN WE HAD ON EARLIER CYCLES. NO MAJOR
CHANGES TO EXPECTATIONS AS FAR AS FRONTAL TIMING WITH THIS FORECAST
PACKAGE. THE FRONT ITSELF IS STILL EXPECTED TO MOVE INTO THE NC
MOUNTAINS AFTER MIDNIGHT SUNDAY MORNING, PROGRESSING EAST. POPS
PEAK EAST OF THE MOUNTAINS DURING THE DAY SUNDAY, STILL IN THE
CATEGORICAL RANGE, WITH ANY PRECIP MOST LIKELY ENDING BEFORE
00Z MON. FORCING WILL WEAKEN AS THE FRONT CROSSES THE CWA AND
SO THE GREATEST QPF IS FORECAST IN THE SOUTHWESTERN MOUNTAINS
AND ESCARPMENT, ADDITIONALLY DUE TO THE POTENTIAL FOR SATURDAY
EVENING CONVECTION BEING GREATEST THERE. LPMM QPF FROM THE HREF
SUGGESTS LOCALIZED SPOTS ALONG THE SOUTH-FACING RIDGES COULD SEE 1"
OR MORE IN 6 HOURS, BUT THAT PRODUCT TENDS TO BE ON THE HIGH END
OF POSSIBLE OUTCOMES. NBM PROBS OF 1"/6H IN THE SAME AREAS ARE NO
BETTER THAN 25%, FOR WHAT THAT IS WORTH. STILL SEEMS REASONABLE
TO SUM UP THE QPF POTENTIAL EAST OF THE MOUNTAINS AS BEING ABOUT
HALF AS MUCH. STILL NOT EXPECTING MUCH IF ANY FLOOD THREAT BUT
ALSO NOT LIKELY TO MAKE A BIG IMPROVEMENT IN SOIL MOISTURE OR
DROUGHT CONDITIONS.
THE OTHER ASPECT OF THE FRONT IS THE POTENTIAL FOR STRONG TO
SEVERE THUNDERSTORMS, BUT THAT TOO CONTINUES TO BE LOW, WITH SMALL
INSTABILITY BEING THE MAIN FACTOR; EARLY MORNING ARRIVAL IN THE
MOUNTAINS IS UNFAVORABLE, BUT THE CAPE VALUES PROGGED UPSTREAM ALSO
ARE NOT ALL THAT IMPRESSIVE. WE ALSO LACK CLASSIC SYNOPTIC ELEMENTS
OF A HIGH-SHEAR LOW-CAPE SETUP. 0-1KM AND 0-3KM SHEAR ARE NOT QUITE
ENOUGH TO EXPECT AN APPRECIABLE THREAT. UPPER DIVERGENCE ASSOCIATED
WITH RIGHT ENTRANCE REGION OF JET STREAK SHOULD PROVIDE SOME DEGREE
OF FORCING FOR ASCENT--ONE REASON WE RETAIN HIGH POPS EAST OF THE
MOUNTAINS--THOUGH THE CORE OF THE JET WILL REMAIN WELL NORTH OF
THE CWA, AND WE WILL LACK THE STRONG DPVA AT 500 MB NOTED AS AN
INGREDIENT FOR HSLC. THE FRONT WILL BE PASSING THE NC/SC PIEDMONT
NEAR PEAK HEATING, SO SOME DESTABILIZATION IS EXPECTED THOUGH LESS
THAN 500 J/KG. WHILE THE THE HRW-FV3 AND NAM-3KM DEVELOP SOME NEW
CONVECTION ALONG THE FRONT, ITS DEPICTIONS ARE UNIMPRESSIVE SO FAR,
IN TERMS OF SEVERE THREAT.
KEY MESSAGE 3: COLD AIR COULD BRING FROST OR A FREEZE TO PARTS OF
THE NC MOUNTAINS, FOOTHILLS, AND NORTHWEST PIEDMONT EARLY NEXT
WEEK. THE MOST LIKELY TIME WOULD BE TUESDAY NIGHT. PROTECTION OF
SENSITIVE VEGETATION MIGHT BE NECESSARY.
STILL EXPECTING TEMPERATURES TO TREND BACK TO NEAR OR SLIGHTLY
BELOW NORMAL SUNDAY NIGHT THROUGH TUESDAY VIA THE CONTINENTAL
HIGH PRESSURE BUILDING IN BEHIND THE FRONT. TEMPS HAVE TRENDED
SLIGHTLY WARMER WITH THE LATEST NBM AND NOW ONLY A FEW AREAS
OF THE NORTHERN MOUNTAINS REACH THE MID-30S WHERE FROST MIGHT
BECOME A CONCERN. GUSTY WINDS SUNDAY NIGHT ARE EXPECTED TO LIMIT
LOCALIZED RADIATIONAL EFFECTS THAT WOULD RESULT IN COLD SPOTS,
AND ALSO LIMIT FROST POTENTIAL; THE EXCEPTION MIGHT BE AREAS THAT
ARE MORE SHELTERED FROM NORTHWEST WINDS. A REINFORCING HIGH WILL
MOVE INTO THE UPPER MIDWEST MONDAY NIGHT, THEN CENTER OVER THE
NORTHEAST US TUESDAY NIGHT. CAA MAY STRENGTHEN IN THE MOUNTAINS
MONDAY NIGHT. GUSTS WILL BE LOWER AT THAT TIME BUT STILL BREEZY
ENOUGH TO LIMIT RADIATIONAL COOLING BY THE SAME TOKENS. WE NOW
EXPECT MONDAY NIGHT'S TEMPS WILL BE SIMILAR TO THE PREVIOUS
NIGHT. THE REINFORCING HIGH WILL HOWEVER COOLER DAYTIME MAXES
TUESDAY IN OUR FAR NORTH AND THEN ALLOW TEMPS TO FALL COOLER IN
ALL AREAS TUE NIGHT, WHEN FROST/FREEZE APPEARS MORE LIKELY IN THE
MOUNTAINS AND PERHAPS PARTS OF THE NC PIEDMONT I-40 CORRIDOR.
THE FROST/FREEZE PROGRAM WILL BE ACTIVATED ON 5 APRIL FOR THE
MOUNTAIN ZONES ALONG AND SOUTHWEST OF I-26 AND ALSO FOR THE
NC PIEDMONT I-40 CORRIDOR (GREATER MCDOWELL EAST TO ROWAN,
AND NORTH). IT IS ALREADY ACTIVE IN AREAS TO THE SOUTH. AS
THE FORECAST STANDS, SOME COMBINATION OF FROST ADV/FREEZE
WARN IS A GOOD BET ACROSS PARTS OF THE MTNS AND FOOTHILLS EARLY
WEDNESDAY. UNFORTUNATELY, THIS ALSO SETS UP THE CONFUSING SITUATION
WHERE THE CENTRAL AND SOUTHERN MOUNTAINS MIGHT GET A FREEZE WARNING
BECAUSE THOSE ZONES ARE ACTIVE, BUT THE NORTHERN MOUNTAINS WILL
NOT GET A WARNING IN SPITE OF BEING EVEN COLDER BECAUSE THE PROGRAM
DOES NOT BECOME ACTIVE UNTIL 21 APRIL.
WITH RESPECT TO FIRE WEATHER, RH LOOKS LIKELY TO DROP BELOW 30
PERCENT ACROSS THE AREA MONDAY THROUGH WEDNESDAY AFTERNOONS,
THOUGH WITH GENERALLY LIGHT WINDS. FUEL MOISTURE WILL HAVE
TO BE MONITORED. FIRE DANGER WILL LIKELY INCREASE DURING THIS
PERIOD. TEMPERATURES WILL REBOUND THURSDAY AS THE HIGH MOVES OFF
THE NORTHEAST COAST, WITH DEWPOINTS TRENDING HIGHER SLIGHTLY AS
WELL. THUS RH MAY NOT BE AS MUCH OF A CONCERN THAT DAY. THERE
APPEARS A SMALL CHANCE OF A COASTAL LOW DEVELOPING BY THURSDAY
NIGHT, BUT AN EVEN SMALLER CHANCE (PER ENSEMBLE MEMBERS) OF SUCH
A LOW BRINGING PRECIP THIS FAR INLAND.
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: SOME LINGERING LOW VFR STRATOCU AND BKN
CIRRUS WILL CONTINUE THROUGH THE EVENING. AN ISOLATED SHOWER IS
POSSIBLE BUT NOT EXPECTED AT THE TERMINALS. LOW LEVEL MOISTURE AND
UPSLOPE FLOW INCREASE OVERNIGHT WITH A RETURN TO MVFR CIGS BEFORE
DAYBREAK. IFR CIGS LOOK LIKELY NEAR DAYBREAK, EXCEPT FOR KAVL WHERE
MVFR CONTINUES. CIGS GO BACK TO MVFR BY MID-MORNING WITH VFR BY 17Z
OR SO. THERE WILL BE SHOWERS IN THE UPSLOPE FLOW NEAR THE SC SITES
AND KAVL, SO HAVE VCSH IN PLACE FOR THOSE. A BETTER CHANCE OF
CONVECTION DEVELOPS DURING THE AFTERNOON, SO PROB30S INCLUDED FOR
THAT. LIGHT S TO SW WIND TONIGHT PICKS BACK UP DURING THE DAY
SATURDAY WITH LOW END GUSTS FOR THE AFTERNOON.
OUTLOOK: A COLD FRONT BRINGS BETTER CHANCES FOR SHRA/TSRA AND
ASSOCIATED RESTRICTIONS SATURDAY NIGHT INTO SUNDAY ACROSS THE
TERMINALS. HIGH PRESSURE BUILDS INTO THE REGION BEHIND THE FRONT
SUNDAY NIGHT INTO THE MIDDLE OF NEXT WEEK ALLOWING DRY AND VFR
CONDITIONS TO RETURN.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
AR/JCW/RWH
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