295
FXUS62 KGSP 250254
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1054 PM EDT SUN MAY 24 2020
SYNOPSIS
AN UPPER RIDGE WILL CONTINUE OVER THE EAST COAST TO START THE WEEK
WHILE A WEAK BACK DOOR COLD FRONT ARRIVES TONIGHT. A MOIST WEDGE-
LIKE WEATHER PATTERN WILL SET UP THROUGH AT LEAST MIDWEEK. UNSETTLED
WEATHER WILL CONTINUE THROUGH THE END OF THE WEEK, AS ANOTHER COLD
FRONT APPROACHES FROM THE NORTHWEST.
NEAR TERM /THROUGH MONDAY/
AS OF 1050 PM SUNDAY: SHOWER AND THUNDERSTORM ACTIVITY HAS MOSTLY
BEEN RELEGATED ALONG THE FRINGE OF THE FORECAST AREA LATE THIS
EVENING. A WEAK DISTURBANCE APPROACHING FROM THE SOUTH AND A
BACKDOOR COLD FRONT WILL CONVERGE ON THE ARE LATER TONIGHT TO BRING
ANOTHER SHOT AT A BIT MORE WIDESPREAD SHOWERS. THE LATEST MODEL
GUIDANCE ISN'T TOO THREATENING AT THIS TIME, BUT THERE COULD BE A
FEW HEAVIER SHOWERS OR EVEN AN ISOLATED THUNDERSTORM. GIVEN THE
LATEST WET CONDITIONS, ISOLATED MINOR FLOODING CAN'T BE RULED OUT.
A BACK DOOR FRONT WILL SLIDE ACROSS THE FORECAST AREA TONIGHT INTO
EARLY MONDAY. THERE REMAINS A CONCERN FOR THE POTENTIAL OF TRAINING
CELLS/LOCALIZED HEAVY RAINFALL AS THIS BOUNDARY PUSHES STEADILY SW
ACROSS THE AREA OVERNIGHT. HOWEVER, GUIDANCE IS SENDING OUT VERY
MIXED SIGNALS REGARDING THIS POSSIBILITY, AND IN FACT, ONLY THE HRRR
AND THE OPERATIONAL NAM IS SIGNALING A HEAVY RAIN THREAT ACROSS THE
AREA (MAINLY THE PIEDMONT) LATE TONIGHT. MUCH WILL LIKELY DEPEND UPON
TO WHAT DEGREE CONVECTION THIS AFTERNOON/EVENING WILL STABILIZE THE
AIR MASS. NEVERTHELESS, A NON-ZERO LOCALLY HEAVY/PERHAPS EXCESSIVE
RAINFALL THREAT WILL EXIST THROUGH THE OVERNIGHT, ESP ACROSS THE
PIEDMONT.
COOLER TEMPS/ENHANCED CLOUD COVER WILL YIELD LESS UNSTABLE AIR
ACROSS THE AREA MONDAY AFTERNOON, EXCEPT PERHAPS ACROSS SOUTHWEST NC
AND THE UPPER SAVANNAH RIVER VALLEY. AT THE SAME TIME, PWATS WILL BE
INCREASING TO ABOVE 1.5, WHILE A SE UPSLOPE FLOW (ALBEIT A WEAK ONE)
BECOMES ESTABLISHED. THE END RESULT SHOULD BE SCATTERED TO NUMEROUS
CONVECTIVE COVERAGE ACROSS THE ENTIRE AREA BEGINNING AS EARLY AS
LATE MORNING. HOWEVER, INTENSITY OF CONVECTION...INCLUDING RAINFALL
RATES SHOULD BE LESS THAN WHAT WE'RE SEEING THIS AFTERNOON.
NEVERTHELESS, A NON-ZERO THREAT FOR EXCESSIVE RAINFALL WILL PERSIST.
MAX TEMPS WILL GENERALLY BE COOLER THAN CLIMO.
SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/
AS OF 1205 PM SUNDAY: AN ABBREVIATED DISCO AS CONVECTION HAS
DEVELOPED OVER THE NC MTNS AND STAFFING IS LIMITED. NOT MUCH CHANGE
WAS MADE TO THE GOING FCST. STILL EXPECT A STG MLVL RIDGE TO
DOMINATE THE PATTERN EARLY ON...BEFORE GIVING WAY TO LOWERING
HEIGHTS AS TROF AXIS SWINGS ARND A CLOSED UPPER LOW ACROSS TX. THIS
TROF WILL AIDE IN BRINGING A TROPICAL WAVE NORTH ALONG THE ATL COAST
THRU THE PERIOD. EXPECT DEEP CONVEC AND HIGH RAINFALL ASSOCIATED
WITH THIS FEATURE WHICH WILL AIDE IN LIMITING MOISTURE FLUX TO OUR
FA TUE. EXPECT MOSTLY CLOUDY SKIES NONETHELESS EACH DAY, WHICH WILL
LIMIT SFC MAX TEMPS A COUPLE CATS BELOW NORMAL AND KEEP INSTABILITY
ON THE LOW END. EASTERLY LLVL FLOW WILL INTERACT WITH THE MTNS AND
THE ADDED LIFT WILL GENERATE AFTERNOON TSTMS WHICH COULD BE GOOD
RAIN MAKERS TUE IN A HIGH PWAT ENVIRON OVER THE SRN ESCARPMENT.
DEEPER MOISTURE WILL MOVES IN ACROSS ALL NON/MTN AREAS WED AND MORE
WIDESPREAD SHOWERS WITH ISOL THUNDER WILL DEVELOP AS THE MOIST FLOW
INTERACTS WITH AN EXISTING SFC RIDGE. SOME ISOL HYDRO ISSUE MAY BE
HAD ACROSS THE SRN BR BY THE END OF THE PERIOD.
LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/
AS OF 1245 PM SUNDAY: STARTING AT 00Z THURSDAY WITH THE OMEGA BLOCK
BREAKING DOWN AND STARTING TO SHIFT EAST WHILE A 500MB CLOSED LOW
WILL BE LOCATED OVER EASTERN TEXAS. A RETURN OF UNSTABLE AFTERNOON
AND EVENING SUBTROPICAL AIR WILL REPLACE THE WEDGE-LIKE PATTERN. THE
CLOSED LOW OVER EAST TEXAS WEAKENS FROM THURSDAY INTO FRIDAY AND
BEGINS TO GET ABSORBED INTO THE MAIN FLOW AS THE TROUGH DROPS DOWN A
BIT FROM THE GREAT LAKES. A SURFACE COLD FRONT WILL BE APPROACHING
OUR AREA FROM THE NORTH AS PLENTY OF MOISTURE WILL BE IN PLACE FOR
MAINLY AFTERNOON AND EVENING CONVECTION. EXPECT CAPE VALUES FROM
1000 TO 1500 ALONG AND SOUTH OF I-85 LATE IN THE DAY UNTIL THE FRONT
MOVES SOUTH. THE FRONT IS EXPECTED TO MOVE THROUGH OUR AREA FROM VA
TO GA DURING THE DAY SATURDAY AND SHOULD BE LOCATED ROUGHLY FROM
ATLANTA TO CHARLESTON SUNDAY MORNING. MAX TEMPERATURES NEAR NORMAL
THURSDAY THROUGH SATURDAY THEN DROPPING SLIGHTLY BELOW ON SUNDAY.
MIN TEMPS A FEW DEGREES ABOVE NORMAL.
AVIATION /03Z MONDAY THROUGH FRIDAY/
AT KCLT AND ELSEWHERE: LOW CONFIDENCE IN 00Z TAFS, ESPECIALLY
BETWEEN 08Z AND 15Z WHEN IFR OR LOWER CIGS/VSBYS ARE EXPECTED TO
DEVELOP ALONG AND AHEAD OF A APPROACH WEAK COLD FRONT FROM THE NE.
AN UPTICK IN SHRA IS POSSIBLE ALONG AND AHEAD OF THIS FEATURE FROM
THE NORTH AND A DISTURBANCE APPROACHING FROM THE SOUTH BY 12Z
MONDAY. MOIST EASTERLY FLOW WILL MEAN ONLY SLOW IMPROVEMENT IN
CIGS/VSBYS BETWEEN 12Z AND 18Z, WHICH MAY HINDER TSRA CHCS,
ESPECIALLY ALONG AND NE OF A LINE FROM KCLT TO KHKY.
OUTLOOK: AFTERNOON TO EVENING SHOWERS AND THUNDERSTORMS WILL BE
POSSIBLE THROUGH THURSDAY. RESTRICTIONS ARE POSSIBLE EACH MORNING
FROM LOW CLOUDS AND FOG, AND AGAIN LATER EACH DAY UNDER ANY
THUNDERSTORMS.
CONFIDENCE TABLE...
03-09Z 09-15Z 15-21Z 21-00Z
KCLT HIGH 98% MED 76% HIGH 91% HIGH 88%
KGSP HIGH 100% MED 68% HIGH 90% HIGH 100%
KAVL HIGH 100% LOW 46% HIGH 83% HIGH 86%
KHKY HIGH 98% MED 78% HIGH 93% HIGH 92%
KGMU HIGH 100% MED 60% HIGH 90% HIGH 100%
KAND HIGH 100% HIGH 86% HIGH 90% HIGH 98%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES ARE AVAILABLE AT
THE FOLLOWING LINK:
WWW.WEATHER.GOV/GSP/AVIATION
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...JDL/65
SHORT TERM...SBK
LONG TERM...DEO
AVIATION...65
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