501
FXUS62 KCAE 181706
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
106 PM EDT THU JUL 18 2019
SYNOPSIS
AN UPPER AND SURFACE TROUGH WILL MOVE INTO THE REGION TODAY AND
PROVIDE BETTER CHANCES OF SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS TODAY AND FRIDAY. A SURFACE TROUGH WILL CONTINUE
TO SUPPORT SCATTERED AFTERNOON THUNDERSTORMS THROUGH THE WEEKEND.
AN UPPER-LEVEL TROUGH WILL DIG INTO THE EASTERN US EARLY NEXT
WEEK WITH A FRONTAL BOUNDARY ENTERING THE REGION MID-WEEK.
NEAR TERM /THROUGH TONIGHT/
UPPER LEVEL TROUGH OVER THE CAROLINAS THIS AFTERNOON AND
OVERNIGHT AS RIDGE HAS SHIFTED SLIGHTLY SOUTH OF THE AREA.
WITH STRONG INSOLATION, RELATIVELY STEEP LOW TO MID LEVEL LAPSE
RATES RESULTING IN MODERATE INSTABILITY AND PERHAPS STRONG LATE
IN THE AFTERNOON. SB CAPE AROUND 2500 J/KG. SOME MID LEVEL DRY
AIR NOTED ON SOUNDINGS AND RELATIVELY HIGH LFC WITH INVERTED V
SUGGEST SOME POTENTIAL FOR STRONG GUSTY WINDS. SO CAN'T RULE OUT
AN ISOLATED SEVERE PULSE STORM. WITH THE POTENTIAL FOR SHORT
WAVE ENERGY, ENHANCED LIFT MAY RESULT IN STRONGER POTENTIAL FOR
CONVECTION. THE LATEST HIGH RESOLUTION MODELS DEVELOP CONVECTION
IN THE PIEDMONT AND MOVE SOUTHEAST ACROSS THE MIDLANDS (LIKELY
SCATTERED) AND POSSIBLY INCREASE TOWARD THE COASTAL PLAIN.
PRECIPITABLE WATER NEAR 1.89 INCHES SO SOME HEAVY RAIN POSSIBLE
BUT STORM MOVEMENT SHOULD LIMIT AMOUNTS. MAX TEMPS IN THE MID TO
UPPER 90S WITH HEAT INDEX AROUND 107 DEGREES. MUGGY TONIGHT
WITH LOWS IN THE MID 70S.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/
TEMPERATURES WILL AGAIN BE IN THE MID TO UPPER 90S WITH MAXIMUM HEAT
INDEX VALUES FROM 100 TO AROUND 105. EXPECT SCATTERED THUNDERSTORMS
EACH AFTERNOON AND EVENING.
AN UPPER RIDGE WILL BE CENTERED NORTH OF THE FORECAST AREA FRIDAY
WITH A WEAK INVERTED TROUGH TO OUR SOUTH. AT THE SURFACE, A LEE-SIDE
TROUGH WILL PROVIDE CONVERGENCE FOR CONVECTIVE DEVELOPMENT. PWAT
VALUES WILL REMAIN HIGH AS ABUNDANT MOISTURE RESIDES OVER THE
REGION WITH VALUES AROUND 2 INCHES. ALL THESE FACTORS SUPPORT
SCATTERED THUNDERSTORM DEVELOPMENT AND A HIGH CHANCE (40%-50%)
OF RAIN. RAIN CHANCES ARE NOT AS HIGH ON SATURDAY AS THE UPPER
TROUGH FLATTENS OUT WITH LITTLE VORTICITY ADVECTION INTO THE
REGION. SEVERE WEATHER POTENTIAL EACH DAY IS LOW GIVEN THE TALL,
SKINNY CAPE PROFILES AND LITTLE DRY AIR ALOFT TO PROMOTE STRONG
DOWNDRAFTS. WITH LESS CONVECTIVE COVERAGE SATURDAY IT MAY BE A
SLIGHTLY WARMER THAN FRIDAY WITH FEWER THUNDERSTORMS TO DISTURB
DIURNAL HEATING. OVERNIGHT LOWS WILL CONTINUE TO BE WARMER THAN
NORMAL WITH VALUES IN THE MID 70S EACH NIGHT.
LONG TERM /SUNDAY THROUGH THURSDAY/
LATE THIS WEEKEND INTO EARLY NEXT WEEK, AN UPPER RIDGE PREVAILS OVER
THE FORECAST AREA WITH PWAT WATER VALUES DROPPING TO AROUND
1.5-1.8 INCHES. THE PRESENCE OF A LEE-SIDE SURFACE TROUGH WILL
CONTINUE TO PROMOTE SCATTERED DIURNAL CONVECTION.
MIDWEEK, A DEEP UPPER LEVEL TROUGH IS FORECAST TO DIG INTO THE
EASTERN US. THIS WILL PUSH A COLD FRONT INTO THE SOUTHEAST
BEFORE STALLING NEAR THE FORECAST AREA. THIS WILL SUPPORT COOLER
DAYTIME TEMPERATURES AND HIGHER RAINFALL CHANCES. THE HIGHEST
CONVECTIVE ACTIVITY WILL DEPEND ON THE LOCATION AND TIMING OF
THE FRONT WHICH WILL BE BETTER KNOWN OVER THE NEXT SEVERAL DAYS.
AT THIS TIME, RAINFALL APPEARS LIKELY ON TUESDAY AND WEDNESDAY
FOR AT LEAST PORTIONS OF THE AREA. THE ECMWF HAS LEANED CLOSER
TO THE GFS TOWARDS THE END OF THE EXTENDED, KEEPING THE STALLED
UPPER LEVEL TROUGH OVER THE EASTERN US FOR A LONGER PERIOD OF
TIME. HIGH TEMPERATURES WILL REMAIN ABOVE NORMAL SUNDAY AND
MONDAY WITH HIGHS IN THE MID 90S BUT THEN FALL TO NEAR NORMAL
WITH INCREASED CLOUDS AND PRECIPITATION ON TUESDAY AND WEDNESDAY
WITH HIGHS IN THE MID TO UPPER 80S.
AVIATION /18Z THURSDAY THROUGH TUESDAY/
UPPER AND SURFACE TROUGH, DIURNAL HEATING, AND SUFFICIENT ATMOSPHERIC
MOISTURE EXPECTED TO RESULT IN INCREASED CONVECTIVE COVERAGE
THIS AFTERNOON/EVENING. HIGH RESOLUTION MODELS SUGGEST SCATTERED
COVERAGE. ISOLATED SEVERE PULSE STORM POSSIBLE. SATELLITE
SHOWING CUMULUS DEVELOPING NORTHWEST OF CAE AT 16Z WITH
THUNDERSTORMS IN NORTH GA MOVING SOUTHEAST. WILL ADD TEMPO
GROUPS TO TERMINALS 20-24Z. CONVECTION WILL DIMINISH MID TO LATE
EVENING WITH MAINLY MID LEVEL CEILINGS OVERNIGHT ALTHOUGH THERE
COULD BE SOME STRATUS LATE. MVFR FOG POSSIBLE AT FOG PRONE SITES
AGS/OGB.
EXTENDED AVIATION OUTLOOK...SCATTERED AFTERNOON/EVENING
THUNDERSTORMS AND SOME POTENTIAL FOR LATE NIGHT/EARLY MORNING
STRATUS/FOG THROUGH THE PERIOD.
CAE WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
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