374
FXUS62 KGSP 181841
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
241 PM EDT THU JUL 18 2019
SYNOPSIS
SUMMERTIME HEAT AND HUMIDITY WILL CONTINUE INTO THE UPCOMING
WEEKEND. THERE IS A GOOD CHANCE OF AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS THROUGH THE PERIOD AS WELL. A COLD FRONT WILL PROVIDE
RELIEF FROM THE HEAT AND HUMIDITY EARLY NEXT WEEK. HOWEVER, CHANCES
FOR SHOWERS AND STORMS WILL CONTINUE.
NEAR TERM /THROUGH FRIDAY/
AS OF 235 PM: MESO-ANALYSIS SHOWS AT LEAST MODERATE CAPE ACROSS THE
AREA WITH VERY HIGH DCAPE VALUES OUTSIDE OF THE MOUNTAINS. AS STORMS
DEVELOP OVER THE HIGHER TERRAIN AND MOVE SOUTHEAST ACROSS THE AREA
THIS AFTERNOON, STRONG TO A FEW SEVERE STORMS ARE LIKELY TO DEVELOP
WITH WET MICROBURSTS BEING THE MAIN THREAT. VERY GUSTY WINDS COULD
DEVELOP FROM ANY STORM TODAY. EXCESSIVE RAINFALL THREAT IS LOW AS
THE STORMS ARE MOVING QUITE WELL, BUT CAN'T RULE OUT AN ISOLATED
FLOOD THREAT IF CELLS TRAIN OVER THE SAME AREA.
A WEAK UPPER TROUGH/WEAKNESS IN THE SUBTROPICAL RIDGE WILL REMAIN IN
PLACE ACROSS THE AREA THROUGH FRIDAY. WEAK SHORT WAVE ENERGY WILL
CROSS THE AREA IN THIS WEAKNESS. UPPER JET DYNAMICS WILL ALSO BE
FAVORABLE FOR SOME UPPER DIVERGENCE THROUGH FRIDAY AS WELL. AT THE
SURFACE, A LEE TROUGH ALSO REMAINS IN PLACE THROUGH THE PERIOD. BEST
OVERALL COVERAGE OF CONVECTION WILL BE THIS AFTERNOON WITH COPIOUS
LOW LEVEL MOISTURE AND MODERATE OR BETTER INSTABILITY. THE GUIDANCE
DIFFERS ON THE COVERAGE FRIDAY AFTERNOON. THEY AGREE ON GOOD
COVERAGE OVER THE MOUNTAINS, BUT DON'T AGREE ELSEWHERE. SOME SHOW
GOOD COVERAGE OVER NE GA AND THE WESTER UPSTATE DIMINISHING TO THE
NORTHEAST. OTHERS SHOW ONLY LOW END SCATTERED OR ISOLATED COVERAGE
OUTSIDE OF THE MOUNTAINS. HAVE GONE WITH A MODEL BLEND WHICH FAVORS
THE MOUNTAINS, NE GA, AND THE WESTERN UPSTATE, BUT KEEPS AT LEAST
LOW END SCATTERED OVER THE REST OF THE AREA. STRONG TO SEVERE STORMS
LOOK TO BE LESS LIKELY FRIDAY AS FORECAST DCAPE IS LOWER, BUT AT
LEAST MODERATE INSTABILITY DEVELOPS WITH SOME MID LEVEL DRY AIR, SO
ISOLATED WET MICROBURSTS CAN'T BE RULED OUT. HIGHS SHOULD BE IN THE
MID 90S ONCE AGAIN WITH HEAT INDEX VALUES 100 OR BETTER ACROSS MUCH
OF THE AREA.
SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/
AS OF 1215 PM THURSDAY: THE CWFA IS PROGGED TO LINGER WITHIN THE
WESTERN PERIPHERY OF BERMUDA HIPRES THIS WEEKEND, MAINTAINING OUR
VERY WARM AND HUMID AIRMASS. SATURDAY REMAINS FORECAST TO BE THE
MOST OPPRESSIVE DAY WITH PIEDMONT APPARENT TEMPERATURES IN THE LOWER
100S BEFORE WE BEGIN TO DIAL BACK THE BORDERINE HEAT ADVISORY
THRESHOLDS ON SUNDAY. THE COVERAGE OF DIURNALLY ENHANCED DEEP
CONVECTION IS EXPECTED TO BECOME NUMEROUS ACROSS THE MOUNTAINS EACH
DAY WHERE TERRAIN EFFECTS AND THE PROXIMITY TO DEVELOPING UPPER
RIDGE WEAKNESS WILL AID IN COVERAGE. NEARER THE SUPPRESSIVE EFFECTS
OF THE UPPER RIDGE, ONLY ISOLATED TSTM COVERAGE IS EXPECTED IN THE
EASTERN CWFA.
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
AS OF 1230 PM THURSDAY: THE PATTERN ACRS THE CONUS WILL CONTINUE TO
AMPLIFY AS THE WORK WEEK GETS UNDERWAY, FEATURING A DEVELOPING L/W
TROUGH IN THE EAST. A BAND OF DEEPER MOISTURE AND BROAD FORCING IS
PROGGED TO PUSH SOUTH INTO THE CWFA AIDING IN THE DEVELOPMENT OF
NUMEROUS SHOWERS AND STORMS MONDAY INTO TUESDAY. WITH FALLING UPPER
HEIGHTS AND CONSIDERABLE CLOUDS AND PCPN, MAXIMUM TEMPERATURES WILL
DIP TO BELOW CLIMO LEVELS BY TUESDAY. FOR THE LATTER HALF OF THE
PERIOD, ATYPICAL LATE JULY CONDITIONS ARE ON TAP AS UPPER TROUGH
AXIS SETTLES ATOP THE REGION. EXPECT IMPINGEMENT OF SOME
CONTINENTAL AIR AND DEEP MOISTURE WILL BE DISPLACED SOUTH AND EAST
OF THE REGION MAINTAINING BELOW NORMAL TEMPERATURE AND HUMIDITY
LEVELS.
AVIATION /19Z THURSDAY THROUGH TUESDAY/
AT KCLT AND ELSEWHERE: ALL SITES SHOULD REMAIN PREDOMINANTLY VFR
THROUGH THE PERIOD. CONVECTION ALREADY GOING THIS AFTERNOON ACROSS
THE WESTERN PORTIONS OF THE FORECAST AREA. HAVE STARTED WITH VCTS
AND TEMPO FOR THOSE SITES AND START AT 19Z FOR KCLT. CONVECTION
SHOULD END BY EARLY EVENING BUT SHOWERS MAY LINGER NEAR KCLT AT
LITTLE LONGER. ANOTHER ROUND OF MTN VALLEY FOG IS LIKELY TONIGHT,
BUT JUST HOW MUCH CONDITIONS DETERIORATE AT KAVL TOMORROW MORNING
WILL DEPEND LARGELY UPON HOW MUCH RAIN THE SITE RECEIVES THIS
AFTERNOON. HAVE GONE WITH MVFR FOR NOW, BUT CONDITIONS COULD GO
EITHER WAY. ONLY PATCHY FOG ELSEWHERE. CONVECTION SHOULD START EARLY
AGAIN FRIDAY, BUT WITH LOWER CHANCES OUTSIDE OF THE MOUNTAINS THAN
TODAY. DID GO WITH PROB30 FOR KCLT THOUGH. SOUTHWEST TO WEST WINDS
TODAY BECOME N TO NW OVERNIGHT THEN W TO NW FOR FRIDAY.
OUTLOOK: TYPICAL, SCATTERED DIURNAL CONVECTION IS EXPECTED THROUGH
THE WEEKEND, ESPECIALLY OVER THE MOUNTAINS. PATCHY MOUNTAIN VALLEY
FOG AND LOW CIGS REMAIN POSSIBLE DURING THE OVERNIGHT AND EARLY
MORNING HOURS. A TRANSITION TO A MORE ACTIVE PATTERN MAY OCCUR
BEGINNING MONDAY.
CONFIDENCE TABLE...
18-24Z 00-06Z 06-12Z 12-18Z
KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAVL HIGH 100% HIGH 100% HIGH 91% HIGH 95%
KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100%
KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:
WWW.WEATHER.GOV/GSP/AVIATION
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
SYNOPSIS...CSH
NEAR TERM...RWH
SHORT TERM...CSH
LONG TERM...CSH
AVIATION...RWH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page