734
FXUS62 KGSP 300629
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
229 AM EDT THU JUL 30 2026
WHAT HAS CHANGED
NO SIGNIFICANT CHANGES TO THE PREVIOUS FORECAST. THE AVIATION
DISCUSSION WAS UPDATED FOR THE 06Z PACKAGE.
KEY MESSAGES
1. NEAR-NORMAL TEMPERATURES WITH RELATIVELY LOW HUMIDITY THROUGH
FRIDAY, AND A NEAR-ZERO CHANCE OF RAIN.
2. ANOTHER FRONTAL SYSTEM IS EXPECTED TO ARRIVE FROM THE WEST
THIS WEEKEND, POSSIBLY STALLING ACROSS OUR AREA EARLY NEXT WEEK,
BRINGING BACK HIGH RAIN CHANCES BUT ALSO BELOW-NORMAL TEMPERATURES.
DISCUSSION
KEY MESSAGE 1: NEAR-NORMAL TEMPERATURES WITH RELATIVELY LOW HUMIDITY
THROUGH FRIDAY, AND A NEAR-ZERO CHANCE OF RAIN.
SFC HIGH PRESSURE SOUTH OF THE GREAT LAKES WILL MAINTAIN LIGHT
NORTHERLY BREEZES OVER MOST OF THE AREA THROUGH TODAY; FRONT WILL
REMAIN STALLED OVER THE SC LOWCOUNTRY AND SOUTH GA. TEMPERATURES
TODAY WILL RUN A COUPLE DEGREES BELOW NORMAL, AND VERY DRY AIR
SHOULD MIX DOWN FROM THE TOP OF THE PBL SUCH THAT DEWPOINTS
FALL WELL INTO THE 50S AT MANY LOCATIONS DURING MID TO LATE
AFTERNOON. RH WILL REACH THE MID TO UPPER 30% RANGE, WITH A FEW
LOCALIZED AREAS CLOSER TO 30% LIKELY. AS THE PREVIOUS SHIFT SAID,
"AAAHHH." THE HIGH WILL SHIFT OVER THE APPALACHIANS TONIGHT AND
WINDS SHOULD TREND LIGHTER; UNDER MOSTLY CLEAR SKIES AND WITH
DEWPOINTS NOT REALLY REBOUNDING MUCH, IT APPEARS REASONABLE TO
FAVOR THE COOLER END OF THE GUIDANCE RANGE FOR FRI MORNING MINS,
SO OUR FORECAST ENDS UP 5-8 DEGREES BELOW NORMAL.
WEAK RETURN FLOW SHOULD DEVELOP IN LOW LEVELS DURING THE DAY
FRIDAY AS THE HIGH SHIFTS TO OUR EAST, PROMOTING SOME DEGREE OF
MOISTURE RETURN, BUT THAT WILL BE OFFSET BY GOOD MIXING INTO STILL
DRY AIR ABOVE THE PBL, AND WITH TEMPERATURES TRENDING SLIGHTLY
WARMER WE END UP WITH SIMILAR MIN RH IN THE AFTERNOON. A SHALLOW
LAYER OF INSTABILITY COULD DEVELOP BELOW THE SUBSIDENCE INVERSION,
SO WE SHOULD SEE AN UPTICK IN DIURNAL CUMULUS THOUGH NOT ENOUGH
TO SUGGEST A RETURN OF MORE THAN SINGLE-DIGIT POPS.
KEY MESSAGE 2: ANOTHER FRONTAL SYSTEM IS EXPECTED TO ARRIVE FROM
THE WEST THIS WEEKEND, POSSIBLY STALLING ACROSS OUR AREA EARLY
NEXT WEEK, BRINGING BACK HIGH RAIN CHANCES BUT ALSO BELOW-NORMAL
TEMPERATURES.
HIGH PRESSURE WILL BE OFFSHORE BY LATE FRIDAY. SOUTHWESTERLY LOW
LEVEL FLOW WILL CONTINUE FRIDAY EVENING, BY WHICH TIME A MATURING
LOW PRESSURE SYSTEM WILL BE PRESENT IN THE UPPER MISSISSIPPI
VALLEY. THIS SYSTEM WILL REMAIN ON A SOUTHEASTWARD TRACK AS
IT BEGINS TO OCCLUDE EARLY SATURDAY MORNING. THE NEAR-SFC FLOW
APPEARS TO BACK SLIGHTLY IN ADVANCE OF THE SYSTEM, WHICH SHOULD
INCREASE MOISTURE TRANSPORT FROM THE ATLANTIC AND DEVELOP CLOUD
COVER DURING THE MORNING. THE FORWARD PROGRESS OF THE SYSTEM SLOWS
AS IT CONTINUES TO OCCLUDE BUT WAA STRENGTHENS ALOFT AND PWATS
MARCH UPWARD THROUGH SATURDAY. VERTICAL PROFILES AGAIN APPEAR AT
LEAST MARGINALLY FAVORABLE FOR DEEP CONVECTION AND POPS INCREASE
STEADILY FROM WEST TO EAST, ALONG WITH ISOLATED TO SCATTERED
THUNDERSTORMS. ASSUMING CLOUD COVER FORMS AS EXPECTED TEMPERATURES
SHOULD REMAIN SIMILAR TO FRIDAY'S ALTHOUGH RH VALUES WILL BE BACK
TO AROUND NORMAL, SO IT WILL BE ON THE MUGGY SIDE.
THE SHORTWAVE APPEARS TO PHASE WITH A BROADER WAVE MOVING ACROSS
THE GREAT LAKES LATE SATURDAY OR SUNDAY, AND THE COMBINED
TROUGH PROMOTES MOIST FLOW FURTHER UP THE EASTERN SEABOARD,
WASHING OUT THE LAST VESTIGES OF THE DRY AIRMASS AND BRINGING
BACK SUBTROPICAL DEWPOINTS AND PWATS SUNDAY, AND THE BEST OVERALL
CHANCE OF PRECIP APPEARS THEN. CLOUDS AND PRECIP HINDER WARMING
SUCH THAT TEMPERATURES END UP 6-9 BELOW NORMAL. THE HIGH PWAT,
DEEP WARM CLOUD LAYER, AND SMALL MBE VECTORS IMPLY A THREAT OF AT
LEAST LOCALLY HEAVY RAINFALL. MODELS STILL MOSTLY SHOW AN UPPER
LOW BEING LEFT BEHIND AS THE NORTHERN TROUGH REMAINS PROGRESSIVE,
AND A CONVERGENCE ZONE STRETCHING OUT BETWEEN THE LOWER MS VALLEY
AND THE NORTHEAST STATES. THERE REMAINS SPREAD AS TO THE POSITION
AND HOW LONG THIS LINGERS OVER OUR REGION BUT IT APPEARS LIKELY
TO LAST THROUGH TUESDAY IF NOT WEDNESDAY. HENCE POPS REMAIN
ABOVE CLIMATOLOGY EACH DAY AND OVERNIGHT PRECIP CANNOT BE RULED
OUT. TEMPERATURES REMAIN BELOW NORMAL BUT TREND GRADUALLY UPWARD
EACH DAY MON-WED.
AVIATION /06Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: DRY AND VFR THRU THE PERIOD ASIDE FROM
SOME MOUNTAIN VALLEY FOG, THOUGH THAT SHOULD NOT AFFECT KAVL. A
FEW CUMULUS MAY BE SEEN EARLY THIS MORNING DUE TO WEAK CONVERGENCE
ALOFT, BUT GIVEN THE DRY CONDITIONS DIURNAL CUMULUS TODAY WILL BE
RATHER SPARSE. WINDS MAINLY NNW TO NE THRU THE PERIOD, POSSIBLY
BACKING TO SW AT KAND DURING THE DAY. A FEW GUSTS MAY OCCUR AT
KAVL AND THE UPSTATE SITES AS WELL.
OUTLOOK: DRY AND VFR THROUGH FRIDAY, WITH SHOWER AND THUNDERSTORM
CHANCES AND ASSOCIATED RESTRICTIONS RETURNING THIS WEEKEND INTO
EARLY NEXT WEEK. LOW STRATUS AND/OR FOG WILL BE POSSIBLE EACH
MORNING STARTING FRIDAY, MAINLY IN THE MTN VALLEYS.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
JCW
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