669
FXUS62 KGSP 290746
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
346 AM EDT SAT MAR 29 2025
SYNOPSIS
SOUTHERLY FLOW AROUND HIGH PRESSURE CENTERED OFF THE EAST COAST
WILL BRING INCREASING MOISTURE AND ABOVE NORMAL TEMPERATURES TO
THE REGION. SHOWER AND THUNDERSTORM CHANCES INCREASE SUNDAY INTO
MONDAY AS A COLD FRONT CROSSES THE AREA. DRY HIGH PRESSURE RETURNS
TUESDAY, FOLLOWED BY ANOTHER APPROACHING FRONT MID-WEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 320 AM: STRONG WESTERN ATLANTIC HIGH PRESSURE NOSING INTO
THE SOUTHEAST CONUS. DEEP SHORTWAVE CENTERED OVER THE ARKLATEX
IS ASSOCIATED WITH PLENTIFUL HIGH ALTITUDE MOISTURE AND WILL
PROVIDE SOME DPVA AS IT TRACKS NORTHEAST INTO KY/TN TODAY,
ALTHOUGH DAMPENING. LIGHT TO MODERATE LOW LEVEL SOUTHERLY FLOW
CONTINUES OVER OUR CWA THIS MORNING; SEA BREEZE APPEARS TO HAVE
REACHED OUR SOUTHERN ZONES WITH DEWPOINTS HAVING TAKEN A SHARP
UPTICK IN THE LAST COUPLE OF HOURS AND WILL CONTINUE TO MAKE SOME
NORTHWARD PROGRESS. AS A RESULT, SUFFICIENT MOISTENING IS SEEN
ON PROG PROFILES, AND SOME LOW STRATUS SHOULD DEVELOP ALONG THE
SOUTH-FACING BLUE RIDGE ESCARPMENT BY DAYBREAK. CAMS, EXCEPTING
THE NAMNEST, DO NOT RESPOND WITH QPF AT THAT TIME. FORCING WITH
THE SHORTWAVE LOOKS TO ARRIVE LATER IN THE DAY WHEN SOME OF THE
LOW-LEVEL MOISTURE WILL HAVE HAD A CHANCE TO MIX OUT. THERE IS
SOME PROGGED SBCAPE BUT THE VERY DRY MIDLEVEL AIR SEEN ABOVE THE
PBL APPEARS TO BE TOO MUCH OF A LIMITING FACTOR FOR UPDRAFTS:
CAMS CONTINUE TO FEATURE VERY LITTLE QPF RESPONSE. A SMALL AREA
OF SLIGHT-CHANCE POP WILL BE RETAINED OVER THE SW NC RIDGES AND
THE WESTERN ESCARPMENT. THE BETTER THERMODYNAMICS WILL BE WEST OF
OUR MOUNTAINS IN TN. LIKEWISE, THE SOUTHERLY FLOW SHOULD CARRY
ANY CELLS DEVELOPING IN THE SMOKIES INTO TN IF THEY CAN SURVIVE
THAT LONG. INCREASED THICKNESSES ARE LIKELY TO BE OFFSET BY CLOUD
COVER TODAY; MAX TEMPS END UP ABOUT THE SAME AS FRIDAY IN OUR EAST,
AND A COUPLE DEGREES COOLER IN THE CLOUDIER WEST HALF.
SYNOPTIC SCALE WARM FRONT APPEARS TO LIFT NORTH INTO THE CWA
TONIGHT IN CONJUNCTION WITH STRENGTHENING LOW PRESSURE IN THE
MIDWEST. LOW-LEVEL FLOW WILL TURN A BIT MORE SOUTHWESTERLY, BUT
MECHANICAL LIFT STILL SHOULD BE PRESENT ALONG THE ESCARPMENT
AND ALSO IN THE SW-FACING RIDGES. MIDLEVEL MOISTURE INCREASES
AND SATURATION SHOULD OCCUR THRU A MUCH DEEPER LAYER, MAINLY
AFTER MIDNIGHT. CAM RESPONSE DOES REMAIN MAINLY ALONG THE
TERRAIN. POPS INCREASE FIRST IN THAT AREA AND THEN EXPAND INTO
THE LOWER ELEVATIONS IN THE SAVANNAH VALLEY, WESTERN UPSTATE,
AND EASTERN NC FOOTHILLS CLOSER TO DAWN SUNDAY. WIDESPREAD LOW
CLOUDS ARE LIKELY TO DEVELOP BY SUNDAY MORNING ALSO. MIN TEMPS
10-15 ABOVE NORMAL UNDER THESE CONDITIONS; HIGH-MIN RECORDS STILL
ARE UNLIKELY TO BE THREATENED.
SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
KEY MESSAGES:
1) SHOWERS AND THUNDERSTORM CHANCE INCREASE SUNDAY THROUGH MONDAY.
2) STRONG TO SEVERE THUNDERSTORMS POSSIBLE MONDAY WITH A COLD
FRONT MOVING INTO THE AREA.
AS OF 300 AM SATURDAY: GUIDANCE IS IN GOOD AGREEMENT ON UNSETTLED
WEATHER FOR SUNDAY THRU MONDAY, AS MOISTURE INCREASES WITHIN
A PERSISTENT SOUTHERLY TO SOUTHWESTERLY FLOW. ISENTROPIC AND
MECHANICAL LIFT WITH SOME ELEVATED CAPE SHOULD RESULT IN SCATTERED
TO NUMEROUS SHOWERS DURING THE DAY SUNDAY, WITH BEST CHANCES IN
THE S- AND SW-FACING SLOPES OF THE MOUNTAINS. FORCING DOESN'T LOOK
SUPPORTIVE OF HEAVY RAINFALL OR STRONG STORMS. BUT A FEW DOWNPOURS
AND LIGHTNING STRIKES WILL BE POSSIBLE IN THE DEEPEST CONVECTION. A
RELATIVE LULL IN POPS IS INDICATED IN THE GUIDANCE SUNDAY NIGHT,
AS ISENTROPIC LIFT WEAKENS. POPS THEN SHOULD PICK UP AGAIN FROM
WEST TO EAST, AS A COLD FRONT APPROACHES FROM THE OH/TN VALLEY. THE
FRONT SHOULD PRODUCE DECENT FORCING, AND THE TIMING STILL LOOKS TO
BE DURING THE PEAK-AFTN/EARLY-EVENING HOURS. THE 00Z GUIDANCE HAS
TRENDED DOWN SLIGHTLY ON THE SBCAPE, BUT STILL A FEW HUNDRED J/KG
COMBINED WITH 0-6 KM BULK SHEAR OF 40-50 KT WOULD SUPPORT STRONG TO
SEVERE STORMS. SOME CURVATURE IN HODOGRAPHS AND MODEL REFLECTIVITY
SUGGESTING SOME DISCRETE CELLS HINT AT SOME SUPERCELLS AND TORNADO
THREAT ALONG WITH THE PRIMARY DAMAGING WIND THREAT. THE FRONT AND
ASSOCIATED CONVECTION SHOULD PASS THRU TO THE EAST BY AROUND 06Z
TUESDAY. TEMPS WILL BE 10-15 DEG ABOVE NORMAL SUNDAY THRU MONDAY,
THEN FALL TO NEAR NORMAL BEHIND THE FRONT MONDAY NIGHT.
LONG TERM /TUESDAY THROUGH FRIDAY/
KEY MESSAGES
1) DRY WEATHER RETURNS TUESDAY WITH RAIN CHANCES INCREASING
BY MIDWEEK.
2) TEMPERATURES WILL WARM TO WELL ABOVE NORMAL LATE IN THE WEEK.
AS OF 320 AM SATURDAY: TUESDAY LOOKS LIKE A RETURN TO NEAR NORMAL
TEMPS AND LOW HUMIDITY, WITH AFTN RH DIPPING INTO THE 30-40%
RANGE. HOPEFULLY, SUNDAY-MONDAY'S RAINFALL AND EXPECTED LIGHT WINDS
TUESDAY WILL LIMIT FIRE WEATHER CONCERNS. THE PATTERN WILL THEN
AMPLIFY THE REST OF THE WEEK, WITH A STOUT 500 MB HIGH BUILDING
OVER THE SOUTHEAST. A SFC HIGH WILL ESTABLISH ITSELF OVER THE
WESTERN ATLANTIC, PUMPING UP THICKNESSES OVER THE REGION. THE 00Z
DETERMINISTIC MODELS DISAGREE ON HOW AMPLIFIED THE RIDGE WILL BE,
WITH THE GFS A LITTLE FLATTER AND ALLOWING A FRONT TO SAG SOUTH
TOWARD THE AREA THURSDAY. THE EC AND CANADIAN SHOW A STRONGER HIGH
AND GENERALLY DRIER WEATHER FOR THE FORECAST AREA. EITHER WAY,
TEMPS WILL BE 10-15 DEG ABOVE NORMAL THURSDAY AND POSSIBLY 15-20
DEG ABOVE NORMAL FRIDAY (MID 80S ACROSS THE PIEDMONT). THE LATEST
NBM POPS RAMP UP INTO THE CHANCE RANGE THURSDAY, BUT THESE MAY BE
OVERDONE IF THE MODELS TREND STRONGER WITH THE RIDGE.
AVIATION /08Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: VFR AT THE TERMINALS THRU AT LEAST SUNSET,
EXCEPT AT KAVL. WILDFIRE SMOKE WILL REDUCE VSBY THERE TO 6-7
SM WITHIN DECOUPLED BOUNDARY LAYER THIS MORNING, AND A BRIEF
RESTRICTION WILL BE POSSIBLE THERE LATE MORNING TO EARLY AFTERNOON
AS PLUME GROWS DIURNALLY AND IS ADVECTED INVOF THE FIELD. ABUNDANT
HIGH ALTITUDE CLOUDS ABOVE FL150 WILL BE SEEN AROUND THE REGION
TODAY WITH SHORTWAVE OVER THE DEEP SOUTH. MECHANICAL LIFT WITHIN
INCREASINGLY MOIST SOUTHERLY FLOW WILL BRING MVFR OR LOWER CLOUDS
TO SOME MOUNTAIN AREAS SW OF KAVL NEAR DAYBREAK BUT NOT LIKELY
AFFECTING ANY TAF TERMINAL; LIKEWISE ISOLATED SHRA COULD DEVELOP
IN THE FAR WESTERN NC MOUNTAINS AND ADVECT INTO TN AND OUT OF THE
AREA. SOUTHERLY WINDS PICK UP AFTER DAYBREAK WITH 15-20 KT GUSTS
THIS AFTN. TONIGHT, THE MECHANICAL LIFT WILL PERSIST, AND WITH
DEEPENING MOISTURE MORE WIDESPREAD MVFR TO IFR CLOUDS WILL DEVELOP,
THE BEST CHANCE BEING NEAR KAVL AND THE SC SITES AFTER 06Z. PROB30
FOR SHRA MAY BE ADDED TO THESE SITES AT NEXT ISSUANCE. A SIGNAL
FOR IFR IS SEEN AT KCLT AFTER 09Z SUN, BUT WITH LOW CONFIDENCE
MADE ONLY A SCT MENTION AT LOW MVFR LEVEL.
OUTLOOK: A FRONTAL SYSTEM WILL BRING INCREASING CHANCES FOR SHOWERS
AND THUNDERSTORMS, ALONG WITH OCCASIONAL RESTRICTIONS ON SUNDAY
AND ESPECIALLY MONDAY. DRYING IS EXPECTED FOR TUE, LIKELY LASTING
INTO WED.
FIRE WEATHER
ALTHOUGH MIXING THIS AFTERNOON WILL TAP INTO A DRY LAYER ABOVE THE
PBL AND DEWPOINTS THUS DIP DIURNALLY, SOUTHERLY FLOW IS PROVIDING
ENOUGH MOISTURE RETURN THIS MORNING THAT RH WILL REMAIN ABOVE 30% IN
ALL AREAS, AND PROBABLY CLOSER TO 50% IN THE HIGHER ELEVATION AREAS
WHERE WILDFIRES ARE ALREADY BEING FOUGHT. THAT SAID, PER
COORDINATION WITH NC STATE OFFICIALS, AN IMPACT-BASED FIRE DANGER
STATEMENT IS CURRENTLY IN PLACE FOR NC ON ACCOUNT OF THE CRITICALLY
DRY FUELS. WIND GUSTS OF 20-25 MPH, BRIEFLY UP TO 30 MPH, WILL BE
POSSIBLE AGAIN THIS AFTERNOON.
PRECIP ACTIVITY THROUGH THIS EVENING IS NOT LIKELY TO HAVE A
SIGNIFICANT IMPACT ON ONGOING WILDFIRES. HOWEVER, CHANCES INCREASE
TOWARD DAYBREAK SUNDAY, WITH THE FASTEST ACCUMULATION RATES LIKELY
TO OCCUR SUNDAY.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...INCREASED FIRE DANGER FROM NOON EDT TODAY THROUGH THIS EVENING
FOR NCZ033-035>037-048>053-056>059-062>065-068>072-082-
501>510.
SC...NONE.
SYNOPSIS...ARK
NEAR TERM...WIMBERLEY
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...WIMBERLEY
FIRE WEATHER...WIMBERLEY
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