Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 060004
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
804 PM EDT SUN JUL 5 2015

.SYNOPSIS...
AN UPPER LEVEL LOW PRESSURE SYSTEM WILL CROSS THE CENTRAL
APPALACHIANS TONIGHT...WITH SLIGHT DRYING ARRIVING FROM THE WEST FOR
MONDAY. LOW LEVEL MOISTURE WILL REMAIN THROUGH THE WEEK...WITH A
RETURN TO A MORE NORMAL PERIOD OF SCATTERED AFTERNOON AND EVENING
THUNDERSTORMS EACH DAY OF THE WEEK. A COLD FRONT WILL APPROACH FROM
THE NORTHWEST TOWARD NEXT WEEKEND.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 730 PM...ONLY SCATTERED SHOWERS REMAIN ACROSS THE WESTERN
CAROLINAS AND NE GEORGIA...ALTHO ONE CONCENTRATED BAND OVER THE SC
MIDLANDS WILL MOVE NORTH AND BRUSH PAST THE WRN NC PIEDMONT ZONES.
THINK IT SAFE TO START A DOWNWARD TREND ON PRECIP PROBABILITY. MAIN
DECISION RIGHT NOW IS WITH THE FLASH FLOOD WATCH. PRECIP AMTS SEEN
IN LATEST MODEL GUIDANCE AND WPC GUIDANCE...COMBINED WITH
DIMINISHING TREND SEEN ON KMRX/KGSP RADAR IMAGERY SUGGESTS LETTING
IT EXPIRE ON SCHEDULE. THINK BETTER CHANCES WILL BE TO OUR NW AND N
THRU LATE EVENING. OTHER FLASH FLOOD THREAT COULD ALSO BE OUTSIDE
THE OLD WATCH...OVER THE EASTERN ZONES IF THAT BAND MOVES ACROSS.
OTHERWISE...WILL MAKE SOME ALTERATIONS TO TEMP TREND TO ACCT FOR
POCKETS OF RAIN COOLED AIR.

REMAINDER OF PREVIOUS DISCUSSION...

THE UPPER LOW WILL SLOWLY FILL AND LIFT NE TONIGHT...WITH THE
ASSOCIATED TROUGH AXIS MOVING EASTWARD INTO THE CENTRAL
APPALACHIANS. DESPITE THE APPROACHING UPPER TROUGH...850 TO 500 MB
LAPSE RATES ARE A RATHER MODEST 5 TO 6 DEG C/KM. RESIDUAL SHOWERS
MAY LINGER ALONG THE WESTERN MTNS IN LOW LEVEL WESTERLY UPSLOPE FLOW
OVERNIGHT...EVEN AFTER ANY DPVA ALOFT HAS PASSED. THE NORTHERN
MOUNTAINS AND FOOTHILLS COULD SEE PERIODS OF HEAVY RAIN THIS
AFTN/EVENING...BUT NOT ENOUGH TO WARRANT EXPANSION/EXTENSION OF THE
WATCH.

THE UPPER TROUGH WILL MOVE SLOWLY EAST ON MONDAY...WITH MORE OF THE
FORECAST AREA GETTING INTO AN NVA REGION THROUGH THE DAY. WITH LESS
CLOUDS AND MORE HEATING...CONVECTION MAY DEVELOP EASTWARD OFF THE
BLUE RIDGE MONDAY AFTN...ESPECIALLY WITH LOW LEVEL CONVERGENCE
FORMING ALONG THE ERN SLOPES AND IN A LEE TROUGH. LAPSE RATES
STEEPEN A BIT MONDAY AFTERNOON...BUT WARM AIR ALOFT IN PROFILES
SHOULD LIMIT CAPE SOMEWHAT. 850 TO 500 MB LAPSE RATES SHOULD STILL
MANAGE TO REACH 6.5 DEG C/KM...AND WITH MID LEVEL DRY AIR WRAPPING
IN...A GENERAL TSTM THREAT WITH LOCALLY GUSTY WINDS SHOULD ARISE.
TEMPS WILL WARM BACK CLOSE TO CLIMO.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AT 230 PM EDT SUNDAY...ON MONDAY EVENING A FILLING UPPER LOW AND
ASSOCIATED VORT LOBE WILL BE LIFTING NE ACROSS THE CENTRAL
APPALACHIANS AND AWAY FROM OUR AREA. NEARLY ZONAL FLOW WILL BE OVER
THE SOUTHERN TIER OF STATES...WITH AN ELONGATED SHORTWAVE MOVING
INTO THE OF AND MID MS RIVER VALLEYS. BY TUESDAY NIGHT AN UPPER
RIDGE OVER THE WESTERN ATLANTIC BUILDS WEST OVER THE SOUTHEASTERN
STATES. THIS RESULTS IN OHIO VALLEY SHORTWAVE ENERGY BEING CHANNELED
EASTWARD TOWARD CHESAPEAKE BAY THROUGH WEDNESDAY...AND REMAINING
NORTH OF OUR AREA.

AT THE SURFACE...MOISTURE ASSOCIATED WITH THE UPPER LOW WILL BE OVER
THE MID ATLANTIC REGION MONDAY EVENING...WITH SLIGHTLY DRIER AIR
WORKING INTO OUR AREA IN WAKE OF THE UPPER LOW. THIS RELATIVE LULL
IN MOISTURE LAST THROUGH TUESDAY NIGHT...FOLLOWED BY A SUBSTANTIAL
MOISTURE INCREASE FROM THE NORTH ON WEDNESDAY...SOUTH OF WEAKENING
AND DECELERATING COLD FRONT IN THE OH RIVER VALLEY.

ALTHOUGH A RELATIVE DRYING TREND IS EXPECTED EARLY ON...ENOUGH
MOISTURE AND INSTABILITY WILL REMAIN FOR PRIMARILY DIURNALLY DRIVEN
CONVECTION ON MONDAY EVENING AND TUESDAY. WITH INCREASING MOISTURE IN
NC ON WEDNESDAY...PRECIPITATION COVERAGE SHOULD BE MORE WIDESPREAD
THERE...BUT INSTABILITY MAY BE MORE LIMITED DUE TO CLOUD COVER
LIMITING HEATING. TEMPERATURES WILL RUN NEAR NORMAL...EXCEPT ALONG
INTERSTATE 40 ON WEDNESDAY...WHERE CLOUD COVER WILL LIMIT DAYTIME
HEATING.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AT 230 PM EDT SUNDAY...ON THURSDAY AN UPPER RIDGE WILL EXTEND FROM
THE WESTERN ATLANTIC TO TX...WITH ZONAL FLOW TO THE NORTH FROM THE
ROCKIES TO ME. THE GFS STRENGTHENS THE RIDGE OVER THE EASTERN USA
INTO THE WEEKEND...WHILE THE ECMWF RETROGRADES IT TO THE SOUTHERN
ROCKIES...ALLOWING FORM SOME SHALLOW TROUGHING OVER THE EAST.

AT THE SURFACE...HIGH PRESSURE WILL BE CENTERED OVER THE SOUTHERN
APPALACHIANS ON THURSDAY...WITH LEE TROUGHING OVER THE PIEDMONT...
AND A STATIONARY FRONT FROM THE OH RIVER VALLEY TO THE DELMARVA
PENINSULA. THIS PATTERN PERSIST THROUGH NEXT SUNDAY. MOISTURE TO THE
SOUTH OF THE BOUNDARY WILL BE GREATER OVER NC THAN SC AND GA. THE
MODELS SHOWS MODEST INSTABILITY...BUT GENERALLY VERY LIGHT STEERING
FLOW...SUGGESTING HEAVY RAINFALL WHERE LIFT CAN BE GENERATED.
TEMPERATURES WILL TREND UPWARD TO ABOVE NORMAL AS HEIGHTS RISE ALOFT.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
AT KCLT...IMMEDIATE CONCERN IS BAND OF TSRA SEEN ON RADAR BETWEEN
KCLT AND KCAE. THINK THE MOVEMENT NNE WILL CARRY IT TO THE EAST OF
THE TERMINAL AND THUS LIGHTNING IS NOT LIKELY VICINITY OF KCLT...BUT
WILL BE READY TO AMEND IF THAT THINKING CHANGES BASED ON RADAR
TRENDS. INSTEAD...WILL KEEP A VCSH IN PLACE THRU THE EVENING
HOURS...UNTIL AT LEAST 03Z...FOR LINGERING SHOWERS. THINK LOW CLOUDS
WILL REMAIN SCT AS LONG AS THE PRECIP BAND SLIPS EAST...WHILE WIND
REMAINS STEADY FROM THE S. OVERNIGHT...CANNOT RULE OUT A LOW CLOUD
CEILING...AS THE RUC INDICATES MVFR IN THE EARLY MORNING HOURS...BUT
THINK AT THIS POINT THE FLOW BECOMING MORE SW OVERNIGHT DOES NOT
FAVOR AS MUCH LOW CLOUD DEVELOPMENT AND THERE ARE NO LOW CLOUD
CEILINGS UPSTREAM TO ADVECT IN. SO...WILL KEEP THE TAF VFR. ON
MONDAY...EXPECT WIND TO COME AROUND LIGHT SW WITH SCT LOW CLOUDS
AGAIN. MODELS NOT EXCITED ABOUT PRECIP CHANCES AWAY FROM THE BLUE
RIDGE AS MID/UPPER LEVELS LOOK UNFAVORABLE...SO WILL LEAVE ANY
MENTION OF PRECIP OUT.

ELSEWHERE...GENERALLY VFR THROUGH THE EVENING WITH SCATTERED
SHOWERS...WHICH WILL BE HANDLED WITH A VCSH. SOME LOCATIONS COULD
HAVE FOG IN THE EARLY MORNING HOURS AND AROUND DAYBREAK...IN THE
MVFR CATEGORY...MAINLY AT KAVL/KAND/KHKY. SHOWER CHANCES DO NOT LOOK
GREAT AWAY FROM THE BLUE RIDGE...SO HAVE LEFT ANY MENTION OUT OF THE
TAFS FOR NOW. EXPECT WIND TO REMAIN SW ON MONDAY...EXCEPT LIGHT NW
AT KAVL.

OUTLOOK...THE WEATHER REGIME WILL RETURN TO A MORE TYPICAL DIURNAL
SUMMERTIME PATTERN THROUGH THE WEEK. THIS WILL MEAN SCATTERED
AFTN/EVENING THUNDERSTORMS OVER THE AREA...MAINLY IN THE MTNS...WITH
ASSOCIATED RESTRICTIONS UNDER THE HEAVIEST SHOWERS...AND SPOTTY LOW
CLOUDS AND FOG THE FOLLOWING MORNING.

CONFIDENCE TABLE...

            00-06Z        06-12Z        12-18Z        18-00Z
KCLT       MED   77%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH  92%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  87%     HIGH  97%     HIGH  94%     HIGH  83%
KHKY       MED   74%     HIGH  90%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH  80%     MED   74%     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: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...HG
NEAR TERM...HG/PM
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...PM



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