849
FXUS62 KGSP 270007
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
807 PM EDT SUN OCT 26 2025
SYNOPSIS
A COLD AIR WEDGE PATTERN SETS UP OVER THE WESTERN CAROLINAS AND
NORTHEAST GEORGIA TONIGHT AND LINGERS THROUGH MID-WEEK BRINGING MUCH
NEEDED RAINFALL AND COLDER TEMPERATURES. CONDITIONS GRADUALLY DRY
OUT BY LATE-WEEK WITH TEMPERATURES REMAINING BELOW NORMAL.
NEAR TERM /THROUGH MONDAY/
AS OF 745 PM EDT SUNDAY: COLD AIR DAMMING REMAINS LOCKED IN ACROSS
THE REGION THROUGH THE PERIOD LEADING TO A DREARY START TO THE
WORKWEEK. WITHIN THE DIFFLUENT FLOW ALOFT DOWNSTREAM OF THE EASTWARD
WOBBLING CLOSED LOW, OVERCAST SKIES WILL LINGER THROUGH THE NEAR
TERM. WITH THE UPPER DIVERGENCE AND DPVA SLUGS, COVERAGE OF LIGHT
RAIN HAS BLOSSOMED OVER THE LAST SEVERAL HOURS. WITHIN THE
INCREASINGLY MOIST UPGLIDE FLOW, RAIN WILL BECOME PROGRESSIVELY
WIDESPREAD AS THE NIGHT WEARS ON. WIDESPREAD RAIN, HEAVY AT TIMES,
WILL CONTINUE ACROSS THE FORECAST AREA ON MONDAY. RAIN WILL HELP
STRENGTHEN THE CAD WEDGE, PROMPTING GUSTY NE WINDS AND LITTLE UPWARD
TEMPERATURE MOVEMENT THROUGHOUT THE DAY. UNDERCUT THE MAXT GUIDANCE
CONSENSUS AND IT REMAINS WITHIN THE REALM OF POSSIBILITY THAT RECORD
LOW MAXT VALUES WILL BE THREATEN (48 OR BOTH KGSP AND KCLT). DESPITE
THE DREARY MONDAY FORECAST, BENEFICIAL RAINFALL ON THE ORDER OF 1 TO
2 INCHES REMAIN POSSIBLE (WITH LOCALLY HIGHER AMOUNTS OF 3+ INCHES
POSSIBLE), WHICH WILL MAKE A DENT IN OUR 60 DAY DEFICITS.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
AS OF 2 PM EDT SUNDAY: A COMPLEX LARGE-SCALE BLOCKING PATTERN WILL
DOMINATE THE PERIOD, WITH AN EVOLVING HYBRID BLOCK TRANSITIONING
TO A REX BLOCK NORTH OF THE AREA. INITIALLY, A SPLIT-FLOW REGIME
FEATURES AN OMEGA BLOCK ACROSS THE NORTHERN STREAM, INCLUDING A
SHORTWAVE RIDGE FROM ONTARIO AND QUEBEC SOUTHWARD THROUGH THE GREAT
LAKES, A DOWNSTREAM CLOSED LOW OFF THE MAINE COAST, AND AN UPSTREAM
TROUGH OVER THE CENTRAL PLAINS. IN THE SOUTHERN STREAM, A SHORTWAVE
ROUNDING THE BASE OF THE JET WILL PASS ACROSS THE SOUTHEAST MONDAY
NIGHT, ALIGNING BENEATH THE NORTHERN RIDGE AND BRIEFLY PRODUCING A
HIGH-OVER-LOW CONFIGURATION. BY TUESDAY, THIS SOUTHERN-STREAM WAVE
AND THE NEW ENGLAND UPPER LOW WILL PHASE, FORMING A MATURE REX
BLOCK NORTH OF THE CAROLINAS. A SECONDARY NORTHERN-STREAM TROUGH
OVER THE CENTRAL PLAINS WILL THEN DIG SOUTHEAST AND PHASE WITH
THE NEWLY FORMED LOW BY WEDNESDAY, PRODUCING A DEEP, SLOW-MOVING
UPPER LOW NEAR OR WEST OF THE APPALACHIANS.
AT THE SURFACE, A COLD-AIR DAMMING (CAD) REGIME WILL REMAIN
ENTRENCHED THROUGH MIDWEEK. DETERMINISTIC MODEL GUIDANCE
CONTINUES TO ERODE THE WEDGE TOO QUICKLY, A KNOWN BIAS IN THIS
PATTERN. CONFIDENCE IS HIGH THAT THE WEDGE WILL PERSIST THROUGH
WEDNESDAY, RESULTING IN BELOW-NORMAL TEMPERATURES, LOW CLOUDS,
AND PERIODS OF OVERRUNNING PRECIPITATION. THE FORECAST LEANS ON
PROBABILISTIC TEMPERATURE GUIDANCE FROM THE NBM, BLENDING TOWARD
THE 75TH TO 90TH PERCENTILE FOR NIGHTTIME LOWS (INDICATING HIGHER
CONFIDENCE IN COOLER NIGHTS UNDER THE WEDGE) AND THE 10TH TO 25TH
PERCENTILE FOR DAYTIME HIGHS (REFLECTING HIGH LIKELIHOOD THAT
DAYTIME WARMING WILL BE LIMITED BY THE SHALLOW COLD LAYER).
WIDESPREAD RAIN IS EXPECTED MONDAY NIGHT AS THE SOUTHERN-STREAM
DISTURBANCE CROSSES THE REGION. THE AREA WILL BE POSITIONED BETWEEN
COUPLED UPPER-JET STREAKS WITH A 50 KT EAST- NORTHEASTERLY LOW-LEVEL
JET ENHANCING OROGRAPHIC ASCENT ALONG THE BLUE RIDGE. ENSEMBLE
QPF GUIDANCE SUPPORTS A HIGH PROBABILITY (AROUND AN 80-TO-90
PERCENT CHANCE) OF MEASURABLE RAIN ACROSS THE ENTIRE CWA, WITH
MOST DETERMINISTIC MEMBERS CLUSTERING AROUND ONE-THIRD TO ONE
INCH OF RAINFALL. A FEW HIGH- RESOLUTION MEMBERS SHOW CONVECTIVE
ENHANCEMENT, CONSISTENT WITH WEAK ELEVATED INSTABILITY (MUCAPE NEAR
100 J/KG AND MID-LEVEL DRYING). SHOULD THIS INSTABILITY MATERIALIZE,
LOCALIZED RAINFALL MAXIMA OF 1.5 TO 3 INCHES CANNOT BE RULED OUT
ACROSS THE NC FOOTHILLS AND WESTERN PIEDMONT BASED ON THE 90TH
AND 95TH PERCENTILE FROM THE HREF AND REFS CAM ENSEMBLES.
A BRIEF LULL IN PRECIPITATION IS EXPECTED TUESDAY THROUGH EARLY
WEDNESDAY AS THE REGION LIES BETWEEN SYSTEMS. ENSEMBLE PROBABILITY
DISTRIBUTIONS SUGGEST A 40-TO-60 PERCENT CHANCE OF LIGHT RAIN OR
DRIZZLE CONTINUING UNDER THE PERSISTENT CAD WEDGE. EVEN DURING
ANY LULL, LOW CLOUDS AND DAMP CONDITIONS WILL LIKELY PERSIST.
RAIN COVERAGE WILL INCREASE AGAIN WEDNESDAY AFTERNOON AND EVENING AS
THE NEXT PHASING UPPER LOW APPROACHES FROM THE WEST. PROBABILISTIC
GUIDANCE SHOWS A 70-TO-90 PERCENT CHANCE OF MEASURABLE RAIN ACROSS
MOST OF THE CWA, WITH THE HIGHEST PROBABILITIES FOCUSED ALONG THE
BLUE RIDGE WHERE SOUTHEAST 850-MB FLOW ENHANCES LIFT. ALTHOUGH
DETERMINISTIC GUIDANCE DEPICTS WARM-FRONTAL EROSION, ENSEMBLE
SPREAD REMAINS LARGE, AND THE MEDIAN SCENARIO KEEPS THE SURFACE
WEDGE INTACT ACROSS MUCH OF THE PIEDMONT. STRONG DYNAMICS AND
ELEVATED INSTABILITY MAY LEAD TO ANOTHER ROUND OF MODERATE RAINFALL
WEDNESDAY NIGHT, WITH ENSEMBLE QPF AVERAGES OF ONE-HALF TO ONE INCH.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
AS OF 2 PM EDT SUNDAY: BY WEDNESDAY NIGHT INTO THURSDAY, THE DEEP
UPPER LOW OVER THE OHIO AND TENNESSEE VALLEYS WILL INTERACT WITH
A DEVELOPING SECONDARY SURFACE LOW NEAR OR EAST OF THE SOUTHERN
APPALACHIANS. WHILE GLOBAL ENSEMBLE MEANS HAVE COME INTO BETTER
ALIGNMENT ON THE GENERAL EVOLUTION, TIMING DIFFERENCES PERSIST
AMONG MEMBERS REGARDING THE TRANSITION BETWEEN THE PRIMARY AND
SECONDARY LOWS. PROBABILISTIC TIMING SPREADS RANGE FROM LATE
WEDNESDAY NIGHT TO THURSDAY AFTERNOON FOR THE FRONTAL PASSAGE
ACROSS THE PIEDMONT. THIS TRANSLATES TO A 50-TO-70 PERCENT CHANCE
THAT MODERATE RAINFALL CONTINUES INTO EARLY THURSDAY BEFORE DRYING
FROM THE WEST AS THE MID-LEVEL DRY SLOT ARRIVES.
AS THE UPPER LOW LIFTS NORTHEAST THURSDAY, ENSEMBLE GUIDANCE
SUPPORTS A 70-TO-90 PERCENT CHANCE OF RAIN ENDING ACROSS THE
PIEDMONT, WHILE THE NC MOUNTAINS MAY MAINTAIN A 60-TO-80 PERCENT
CHANCE OF LINGERING LIGHT PRECIPITATION DUE TO UPSLOPE FLOW.
FRIDAY WILL FEATURE POST-FRONTAL COLD ADVECTION AND WESTERLY
WINDS. ENSEMBLE TEMPERATURE SPREADS OF 7 TO 10 DEGREES SUGGEST
BELOW-NORMAL CONDITIONS WITH HIGHS 10 TO 15 DEGREES BELOW NORMAL IN
THE MOUNTAINS AND 5 TO 10 DEGREES BELOW ELSEWHERE. THE PROBABILITY
OF DRY CONDITIONS FRIDAY AFTERNOON AND EVENING EXCEEDS 80 PERCENT,
OFFERING IMPROVING CONDITIONS FOR OUTDOOR ACTIVITIES.
THROUGH THE WEEKEND, BROAD UPPER TROUGHING WILL PERSIST OVER THE
EASTERN UNITED STATES. ENSEMBLE MEANS INDICATE HIGH CONFIDENCE
(AROUND 70-TO-90 PERCENT PROBABILITY) OF CONTINUED DRY WEATHER
THROUGH SATURDAY, FOLLOWED BY INCREASING UNCERTAINTY BY SUNDAY
AS THE NEXT SYSTEM APPROACHES FROM THE WEST. TIMING SPREADS
EXCEED 24 HOURS AMONG ENSEMBLE MEMBERS, WITH ROUGHLY A 40 PERCENT
PROBABILITY OF OVERRUNNING PRECIPITATION REACHING THE AREA BY LATE
SUNDAY. TEMPERATURES WILL GRADUALLY MODERATE BUT REMAIN SEVERAL
DEGREES BELOW NORMAL THROUGH THE WEEKEND.
AVIATION /00Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: CONDITIONS WILL GRADUALLY DETERIORATE THROUGH
THE 00Z TAF PERIOD AS A WEDGE OF COLD AIR REMAINS LOCKED IN PLACE.
RAIN CHANCES WILL CONTINUE TO INCREASE THROUGH TONIGHT, WITH THE
ENTIRETY OF THE WESTERN CAROLINAS SEEING RAIN, WITH MODERATE TO
HEAVY DOWNPOURS AT TIMES, ON MONDAY. OVC CIGS WILL GRADUALLY LOWER
TO MVFR TO IFR LEVELS OVERNIGHT INTO MONDAY MORNING, BECOMING IFR TO
LIFR MONDAY AFTERNOON/EVENING. WITH HIGH CONFIDENCE ON PRECIP, OPTED
TO GO WITH PREVAILING RAIN ACROSS THE TERMINALS THIS EVENING THROUGH
THE END OF THE TAF PERIOD. WINDS WILL REMAIN NE EAST OF THE
MOUNTAINS AND SE/E AT KAVL THROUGH THE PERIOD. WIND SPEEDS WILL
GRADUALLY INCREASE OVERNIGHT INTO MONDAY, WITH LOW-END GUSTS
DEVELOPING ACROSS MOST OF THE TERMINALS, WITH THE EXCEPTION OF KHKY.
OUTLOOK: WIDESPREAD RAIN, GUSTY WINDS, AND RESTRICTIONS LINGER
THROUGH AT LEAST TUESDAY MORNING. CONFIDENCE IS LOW ON HOW MUCH
CONDITIONS WILL IMPROVE TUESDAY, BUT PERIODIC RAIN/RESTRICTIONS
RETURN WEDNESDAY INTO THURSDAY. DRIER WEATHER RETURNS TO END THE
WEEK.
CLIMATE
RECORDS FOR 10-27
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 85 1939 37 1957 62 1939 23 1962
KCLT 86 1939 48 1957 71 2010 24 1962
1919
KGSP 86 1891 48 1957 69 2010 30 1962
RECORDS FOR 10-28
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 81 2023 41 1910 62 1984 23 1914
1940 1918
KCLT 87 1940 49 1976 67 1919 26 2001
KGSP 85 1991 51 1976 66 1919 27 1914
1903
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...AR/CSH
NEAR TERM...AR/CSH
SHORT TERM...JK
LONG TERM...JK
AVIATION...AR
CLIMATE...GSP
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