Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KGSP 221009
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
609 AM EDT TUE JUL 22 2014

.SYNOPSIS...
A WEAK UPPER LOW WILL MOVE AWAY TO THE WEST TODAY WHICH SHOULD ALLOW
FOR A BRIEF RETURN TO MORE TYPICAL SUMMER WEATHER FOR WEDNESDAY.
HOWEVER...A FRONT WILL APPROACH AND MOVE ACROSS THE REGION ON
THURSDAY. THE PASSAGE OF THE FRONT WILL NOT BRING COOLER AIR...BUT
IT SHOULD BRING DRIER AIR FOR FRIDAY AND INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 6 AM...REGIONAL RADAR CONTINUES TO SHOW NUMEROUS AREAS OF
DRIZZLE OR LIGHT RAIN ACROSS THE REGION. A CLUSTER OF SHOWERS ACROSS
THE MIDLANDS EARLY THIS MORNING WAS TRACKING NORTHWEST. THESE
SHOWERS MAY REACH THE I-85 CORRIDOR BY 13Z. I WILL UPDATE THE
FORECAST TO TWEAK POP TIMING AND PLACEMENT. IN ADDITION...I HAVE
POPULATED THE VIS FORECAST WITH A BLEND OF LATEST
GUIDANCE...WEIGHTED TOWARDS THE LAMP.

AS OF 330 AM...RECENT W/V IMAGES INDICATE THAT THE CENTER OF THE MID
LEVEL LOW WAS LOCATED NEAR THE PANHANDLE OF FL. DEEP MOISTURE HAS
SPREAD ACROSS MOST OF THE SOUTHEAST U.S...LIFTING PW UP TO 2
INCHES...OR 125 PERCENT OF NORMAL. FORECAST SOUNDINGS SHOW THAT DEEP
SKINNY CAPE WILL EXIST ACROSS THE REGION TODAY...WITH CAPE VALUES
AROUND 1000 J/KG. THE COMBINATION OF WEAK ISENTROPIC LIFT...EAST H85
WINDS...AND LFC BETWEEN 3-4 KFT SHOULD RESULT SCT TO NUMEROUS
SHOWERS AND THUNDERSTORMS TODAY. STORM MOTIONS WILL LIKELY REMAIN
LESS THAN 10M/S. HEAVY DOWNPOURS AND CLOUD TO GROUND LIGHTNING WILL
BE THE PRIMARY THREATS. OVERCAST TO MOSTLY CLOUDY SKY AND PERIODS OF
RAIN SHOULD LIMIT HEATING TODAY. HIGH TEMPERATURES ARE FORECAST TO
RANGE FROM THE U70S WITHIN THE MTN VALLEYS TO THE LOW 80S EAST.

TONIGHT...NEAR TERM MODELS INDICATE THAT THE MID LEVEL LOW WILL
TRACK WEST...ALLOWING HEIGHTS TO RISE ACROSS THE FORECAST AREA. H85
WINDS WILL VEER FROM THE SW...RESULTING IN DOWNSLOPE FLOW ACROSS THE
FOOTHILLS AND ENDING LLVL ISENTROPIC LIFT. POPS WILL QUICKLY
DECREASE AFTER SUNSET...FALLING TO SCHC LATE TONIGHT. LOW
TEMPERATURES WILL REMAIN NEAR NORMAL.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AS OF 230 AM EDT TUESDAY...IT LOOKS LIKE A TRANSITION OF SORTS WILL
BE COMPLETE BY WEDNESDAY MORNING...AS THE WEAK UPPER LOW WILL HAVE
RETROGRADED FAR ENOUGH FOR THE CYCLONIC FLOW TO HAVE MOVED WEST OF
THE FCST AREA. THAT WILL BRING THE FLOW AROUND TO SOMETHING MORE SW
TO W FOR THE FIRST PART OF THE SHORT RANGE...WITH STILL PLENTY OF
LOW LEVEL MOISTURE REMAINING TO FUEL DIURNAL SHOWERS AND
THUNDERSTORMS. AM A BIT SURPRISED WITH THE LACK OF COVERAGE IN THE
NAM SOLUTION FOR WEDNESDAY AFTERNOON/EVENING AND THINK THAT THE
ENTIRE FCST AREA WILL SEE SCATTERED STORMS...SO THE FCST STAYS MORE
IN LINE WITH THE GREATER COVERAGE SEEN ON THE GFS. EXPECT MOST OF
THE ACTIVITY TO WEAKEN/END GRADUALLY WITH LOSS OF HEATING WEDNESDAY
NIGHT E OF THE MTNS...BUT BY THEN A COLD FRONT WILL APPROACH FROM
THE NW WHICH WARRANTS KEEPING THE CHANCE POP OVERNIGHT OVER THE
MTNS. THE NEW GUIDANCE SHOWS A STRONGER PUSH BY A SHORT WAVE HELPING
TO CARVE OUT A NEW EASTERN UPPER TROF ON THURSDAY. THIS FEATURE IS
NOW EXPECTED TO PUSH THE COLD FRONT ALL THE WAY THROUGH THE FCST
AREA THURSDAY AFTERNOON AND EVENING...BUT THE PROBLEM NOW IS THE
TIMING. THE NAM BRINGS IT THROUGH EARLIER AND DRIVES THE FRONT
FARTHER S THAN THE OTHER GUIDANCE. THE FRONT APPEARS A BIT STRONGER
WHICH MAKES ME THINK WE ARE LIKELY TO SEE SHOWERS AND STORMS OVER
MOST OF THE FCST AREA...HOWEVER...UNCERTAINTY ABOUT WHEN THE MOST
LIKELY TIME OF THE STORMS WILL BE ACTUALLY RESULTS IN A SLIGHT
DECREASE IN THE PRECIP PROBABILITY FOR THE DAY AS A WHOLE. ONCE THE
TIMING IS MORE CERTAIN...EXPECT THIS TO CREEP BACK TOWARD THE LIKELY
CATEGORY. THE PRECIP CHANCES SHOULD SLOWLY DIMINISH AND PUSH OFF TO
THE S THROUGH EARLY FRIDAY MORNING. TEMPS WILL ALSO COOL DOWN A BIT
THURSDAY NIGHT AS DRY AIR COMES IN BEHIND THE FRONT.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AS OF 315 AM TUESDAY...THE NEW GUIDANCE FOR THE START OF THE MEDIUM
RANGE CONFIRMS THAT THE SURFACE FRONT WILL PROBABLY BE DRIVEN SOUTH
OF THE FCST AREA BY FRIDAY MORNING GIVING US A CLEANER FRONTAL
PASSAGE THAN EARLIER THOUGHT. WITH THIS TREND ESTABLISHED IN THE
GUIDANCE...THE PRECIP CHANCES WERE LOWERED INITIALLY ON FRIDAY.
HOWEVER...IT IS HARD TO RULE OUT SOME SHOWER ACTIVITY BEHIND THE
FRONT ON FRIDAY AFTERNOON AS THERE DOES NOT APPEAR TO BE ENUF TO
SUPPRESS DEEP CONVECTION...SO A SLIGHT CHANCE WAS KEPT OVER MOST OF
THE FCST AREA PER THE MOSGUIDE...WITH A CHANCE ON THE SE FRINGE.
TEMPS WILL NOT DROP MUCH AT ALL BEHIND THE FRONT...BUT HOPEFULLY
THERE WILL BE ENUF DROP IN THE DEWPOINT TO MAKE THE RH FALL. NO
OTHER CHANGES WERE MADE TO THE MEDIUM RANGE. THE GFS SUGGESTS SOME
MCS-LIKE ACTIVITY MOVING IN FROM THE WEST ON SUNDAY BUT CONFIDENCE
IN THAT IS LOW. THERE IS DECENT AGREEMENT BETWEEN THE GFS AND ECMWF
WITH THE PASSAGE OF ANOTHER FRONT NEXT MONDAY...SO WE WILL CONTINUE
TO FEATURE THE HIGHEST PRECIP CHANCES IN THE MEDIUM RANGE ON THAT
DAY.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
AT KCLT...LATEST OBSERVATION INDICATED MVFR CLOUDS ACROSS THE
TERMINAL. RECENT TCLT SCANS SHOW A PATCH OF LIGHT REFLECTIVITY
ACROSS CABARRUS DRIFTING WEST...WITH ANOTHER AREA OF LIGHT RAIN
LIFTING NORTHWEST ACROSS THE MIDLANDS. GUIDANCE AND TRENDS INDICATE
THAT IFR CEILINGS WILL DEVELOP BETWEEN 6Z TO 8Z. ONCE THE LOW
CEILING ARRIVE...CONDITIONS SHOULD REMAIN UNTIL MID MORNING.
HOWEVER...MVFR CEILINGS WILL BE SLOW TO IMPROVE UNDER WIDESPREAD
HIGH CLOUD COVER. BASED ON FAVORED GUIDANCE...VFR CLOUDS ARE
EXPECTED BY 19Z. I WILL MAINTAIN A PROB30 FROM 19Z-24Z FOR MVFR
CONDITIONS DURING TSRA.

ELSEWHERE...THE INITIAL GROUP OF THE 6Z TAFS WILL RANGE FROM VFR AT
HKY TO MVFR ELSEWHERE ACROSS THE WESTERN CAROLINAS. AT 2 AM...RECENT
IMAGES INDICATE AN EXPANSION OF LIGHT REFLECTIVITY ACROSS THE
UPSTATE...WITH ANOTHER BAND LIFTING NW ACROSS THE MIDLANDS. THE
DEVELOP OF THE -RA WILL LIKELY SIGNAL THE DEVELOPMENT OF IFR
CEILINGS...EXPECTED BY 9Z. ONCE THE LOW CEILING ARRIVE AND
DEVELOP...CONDITIONS SHOULD REMAIN UNTIL MID MORNING. HOWEVER...MVFR
CEILINGS WILL BE SLOW TO IMPROVE UNDER WIDESPREAD HIGH CLOUD COVER.
BASED ON FAVORED GUIDANCE...VFR CLOUDS ARE EXPECTED BY MID DAY. I WILL
MAINTAIN A PROB30 FROM 18Z-24Z FOR MVFR CONDITIONS DURING TSRA.

OUTLOOK...A GRADUAL RETURN TO A MORE TYPICAL PATTERN WITH DIURNAL
SHOWERS AND STORMS IS EXPECTED WEDNESDAY. A FRONTAL SYSTEM
APPROACHING FROM THE NORTHWEST WILL CROSS THE REGION THURSDAY
NIGHT...BRINGING STRONGER CONVECTION AND POSSIBLE FLIGHT
RESTRICTIONS THROUGH FRIDAY.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-10Z
KCLT       MED   74%     HIGH  93%     HIGH 100%     HIGH 100%
KGSP       HIGH  82%     HIGH  90%     HIGH 100%     HIGH 100%
KAVL       MED   71%     HIGH  89%     MED   66%     MED   66%
KHKY       MED   68%     HIGH  90%     HIGH  98%     HIGH  91%
KGMU       HIGH  83%     HIGH  91%     HIGH 100%     HIGH 100%
KAND       MED   78%     HIGH  95%     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: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

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

&&

$$
SYNOPSIS...PM
NEAR TERM...NED
SHORT TERM...PM
LONG TERM...PM
AVIATION...NED






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.