Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | 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 300736
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
336 AM EDT MON MAR 30 2015

.SYNOPSIS...
A COLD FRONT WILL PUSH THROUGH THE REGION THIS MORNING AHEAD OF
REBUILDING HIGH PRESSURE FOR TUESDAY.  ANOTHER WEAK COLD FRONT WILL
ARRIVE ON TUESDAY NIGHT WITH HIGH PRESSURE QUICKLY BUILDING FOR
WEDNESDAY LASTING THROUGH THURSDAY.  FRIDAY NIGHT WILL BRING THE
PASSAGE OF ANOTHER COLD FRONT...WITH COOLER AND DRIER HIGH PRESSURE
PREVAILING FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 230 AM...WE ARE SEEING AN INCREASE IN PRECIP COVERAGE TO THE
WEST WHERE THE FRONTAL BOUNDARY WAS INTERCEPTING THE STRONGER LOW
LEVEL JET AND MOISTURE PLUME ACROSS TN/NRN MS. A FEW SHOWERY
ELEMENTS WERE NOTED OVER ERN TN...BUT THIS WAS PROBABLY NOT REACHING
THE GROUND. WILL PUT OFF THE ONSET OF PRECIP FOR ANOTHER HOUR OR
TWO...WHICH HAS THE ADDED BENEFIT OF ALLOWING WARM ADVECTION TO
BRING THE TEMPS UP ABOVE FREEZING AT THE PEAKS OF THE NC MTNS. ALL
INDICATIONS REMAIN THAT PRECIP WILL IN FACT BLOSSOM TO THE WEST THRU
THE PRE-DAWN HOURS AND REACH THE WESTERN CAROLINAS BY/AROUND
DAYBREAK. A CONTINUED UPWARD TREND TO PRECIP COVERAGE OVER SRN
MIDDLE TN/NRN AL IS A GOOD INDICATION THAT THE MODELS ARE ON THE
RIGHT TRACK.

THE MODELS TAKE THE BAND OF PRECIP AHEAD OF THE FRONT EASTWARD
ACROSS THE FCST AREA FAIRLY RAPIDLY THIS MORNING...AS THE SHORT WAVE
ROTATES QUICKLY AROUND THE BOTTOM OF THE UPPER TROF. THIS SHOULD
DRIVE THE SURFACE FRONTAL ZONE EAST OF THE REGION BY MIDDAY. WILL GO
WITH THE HIGHEST PRECIP PROBABILITY ACROSS THE SRN MOUNTAINS/NE
GEORGIA/WRN UPSTATE AS THE BEST LOW LEVEL FORCING STRETCHES INTO
THAT REGION FROM THE WEST EARLY THIS MORNING. COVERAGE SHOULD BE NOT
AS GREAT ALONG/N OF I-40 WHERE DOWNSLOPE E OF THE MTNS WILL BE
UNFAVORABLE. WHT REMAINS TO BE SEEN IS IF ANY EMBEDDED THUNDERSTORMS
CAN SURVIVE INTO THE MORE UNFAVORABLE AIR MASS ACRS N GEORGIA.
PRECIP CHANCES RAMP DOWN QUICKLY BY MIDDAY. TEMPS SHOULD REBOUND
NICELY...ABOUT TEN DEGREES ABOVE YESTERDAY...IN SPITE OF THE SFC
BOUNDARY MOVING THRU...BECAUSE OF THE W/NW DOWNSLOPE FLOW IN THE
AFTERNOON.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 300 AM EDT MONDAY...THE SHORT TERM FCST PERIOD INITIALIZES
TUESDAY MORNING AMIDST CONTINUED NW FLOW PATTERN ALOFT...HIGHLIGHTED
BY A NORTHERN STREAM SHORTWAVE SLIDING THROUGH THE SOUTHERN GREAT
LAKES REGION.  WEAK SURFACE CYCLOGENESIS BENEATH WILL AID COLD FRONTAL
PROGRESSION ACROSS THE MIDWEST INTO THE OHIO VALLEY ON TUESDAY AHEAD
OF SPRAWLING HIGH PRESSURE.  MEANWHILE ACROSS THE SOUTHERN PLAINS
ANOTHER SURFACE WAVE WILL FORM IN THE LEE OF THE SOUTHERN ROCKIES
ALLOWING FOR DEVELOPMENT OF MODEST BAROCLINIC ZONE OVER THE
SOUTHEAST TUESDAY AFTERNOON INTO WEDNESDAY.  WARM FRONT LEADING THE
CHARGE NORTHWARD ON TUESDAY WILL ADVANCE INTO THE I20 CORRIDOR LATE
IN THE DAY WITH ACTIVATION LIKELY AS MORE UNSTABLE AIR ADVECTS
NORTHWARD.  AS THE ABOVE MENTIONED COLD FRONT CONTINUES TO SLIDE
SOUTH THROUGH THE TN VALLEY...EXPECTING CONVECTION ALONG THE FRONTAL
ZONE WHICH COULD PUSH INTO THE WESTERN NC MTNS LATE TUESDAY NIGHT.
MODELS CONTINUE TO HINT AT SOME RESIDUAL INSTABILITY AFTER SUNSET
AHEAD OF THE FRONT...HOWEVER DECREASING WITH HEATING LOSS...AND
DRIER AIR ADVECTION BEHIND THE FRONT AS IT BACK DOORS INTO THE
REGION.  THE FRONT WILL SLIDE SOUTH THROUGH THE REMAINDER OF THE
FCST AREA OVERNIGHT...AS HIGH PRESSURE SETS UP ALONG THE EASTERN
SEABOARD.  BRIEF HEIGHT RISES ALOFT COMBINED WITH RIDGING AT THE
SURFACE WILL KEEP THE WX DRY ON WEDNESDAY AHEAD OF RETURNING MOIST
SOUTHERLY UPGLIDE ATOP POSSIBLE INSITU CAD THURSDAY MORNING.

AS FOR THE FCST...POPS WILL SLOWLY INCREASE INTO TUESDAY EVENING
ACROSS THE NORTHEAST GA AND WESTERN NC MTNS TO ACCOUNT FOR WEAK
FRONTAL ZONE ASSOCIATED CONVECTION...WITH POPS REMOVED BY MID
MORNING WEDNESDAY AS THE COLD FRONT SLIDES THROUGH.  POPS WILL
REMAIN BELOW MENTIONABLE LEVELS THROUGH THE DAY WEDNESDAY BEFORE
INCREASING MID/LATE EVENING AS MODELS CONTINUE TO HINT AT WEAK
INSITU CAD REGIME ON THE WESTERN FLANK OF THE COASTAL SFC RIDGE.  GFS
ISENTROPIC CHARTS INDICATE IMPROVING UPGLIDE IN THE LOW
LEVELS...THUS CHANCE LEVEL POPS WERE FAVORED OVER THE WESTERN HALF
OF THE FCST AREA TAPERING TO SLIGHT CHANCE FURTHER EAST ON THE
FRINGE OF UPGLIDE MAXIMA.  TEMPERATURES THROUGH THE PERIOD WILL
REMAIN ABOVE NORMAL LEVELS DESPITE THE WEAK FROPA TUESDAY NIGHT.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 315 AM EDT MONDAY...THE MEDIUM RANGE FCST PERIOD INITIALIZES
THURSDAY MORNING AMIDST ONGOING UPGLIDE/UPSLOPE PRECIP ACROSS MUCH OF
THE SOUTHWEST NC AND NORTHEAST GA MTNS.  WEAK INSITU CAD REGIME
RESULTANT FROM ANCHORED COASTAL HIGH OFF THE NC COAST WILL BREAK
DOWN THROUGH LATE MORNING LEADING TO EROSION OF ANY UPGLIDE
ENHANCEMENT.  SOUTHERLY FLOW AT THE SURFACE WILL CONTINUE LEADING TO
IMPROVING WAA REGIME INTO FRIDAY.  MEANWHILE...A NORTHERN STREAM
UPPER WAVE WILL SLIDE ACROSS THE UPPER MIDWEST WHILE A COLD FRONT
STRETCHES TO THE SOUTH FROM SUBSEQUENT SFC LOW.  MODELS CONTINUE TO
PROG THE FRONT ALONG THE OH RIVER VALLEY THURSDAY EVENING WITH AN
IMPROVING WARM SECTOR AIRMASS OUT AHEAD.  THE ECMWF/GFS TREND
TOWARDS SOME DISCONTINUITY LATE IN THE WEEK REGARDING TIMING OF THE
FROPA ACROSS THE SOUTHERN APPS.  THE ECMWF FAVORS A FASTER SOLUTION
WHICH BRINGS THE FRONT INTO THE MTNS OF WESTERN NC FRIDAY AFTERNOON
OR EARLY EVENING WITH PERHAPS ISOLATED CONVECTION AHEAD IN THE
MILDLY UNSTABLE AIRMASS...WHILE THE GFS SEEMS ABOUT 6 HOURS SLOWER
THAN THAT OF THE ECMWF.  BOTH SOLUTIONS WOULD FAVOR A NOCTURNAL
FROPA THUS LIMITING THE AMOUNT OF POTENTIAL INSTABILITY AVAILABLE
FOR CONVECTION.  BEYOND THAT THE FRONT SHOULD EXIT THE REGION TO THE
EAST BY MIDDAY SATURDAY AT THE LATEST ALLOWING FOR COOLER/DRIER HIGH
PRESSURE TO ADVECT IN FROM THE WEST.  TEMPERATURES THROUGH THE
PERIOD WILL WARM TO WELL ABOVE NORMAL LEVELS FOR THURSDAY AND
FRIDAY...WITH SLIGHTLY COOLER YET STILL ABOVE CLIMO LEVELS FCST FOR
THE WEEKEND.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS THRU THE EARLY MORNING HOURS
AS A PATCH OF LOW CLOUDS WITH A BASE OF 050-060 MOVES EAST ACROSS
THE PIEDMONT OF THE CAROLINAS. CONDITIONS SHOULD DETERIORATE TOWARD
DAYBREAK AS A BAND OF PRECIP AHEAD OF A COLD FRONT MOVES IN FROM THE
WEST. THE PRECIP IS FCST TO FILL IN ALONG THE FRONT AND BRING AT
LEAST A TEMPORARY MVFR CEILING/VIS RESTRICTION TO ALL TAF SITES
VARIOUSLY IN THE 09Z TO 15Z TIME FRAME FROM W TO E. UNFORTUNATELY...
SKEPTICISM REMAINS. UNTIL THE PRECIP ACTUALLY DEVELOPS AND FILLS
IN...CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE THE SHOWERS AS MORE
THAN A TEMPO GROUP. WILL ALSO NOT INCLUDE ANY IFR RESTRICTIONS FOR
THE SAME REASON. THE FRONTAL ZONE WILL MOVE ACROSS THE REGION DURING
THE LATE MORNING AND EARLY AFTERNOON AND WILL BRING A WIND SHIFT TO
W AND THEN WNW BY MID AFTERNOON...WITH CONDITIONS BECOMING VFR ONCE
AGAIN. ALL SITES SHOULD HAVE ONLY SCATTERED CIRRUS FOR THE REST OF
THE PERIOD WITH WIND REMAINING NW THRU THE EVENING. WIND MAY GO
LIGHT NW OR PERHAPS CALM TOWARD THE END OF THE PERIOD...BUT THOSE
DETAILS WERE OMITTED FOR BREVITY.

OUTLOOK...VFR FROM EARLY TUESDAY MORNING THROUGH WEDNESDAY. AN
APPROACHING WARM FRONT AND RESULTANT MOISTURE RETURN WILL BRING
BETTER CHANCES FOR PRECIP/RESTRICTIONS ACROSS THE AREA LATER IN THE
WEEK...PERHAPS STARTING THURSDAY MORNING. EVENTUALLY...A SLOW MOVING
COLD FRONT WILL AFFECT THE AREA FRIDAY OR SATURDAY WITH MORE
RESTRICTIONS.

CONFIDENCE TABLE...

            07-13Z        13-19Z        19-01Z        01-06Z
KCLT       HIGH 100%     HIGH  84%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     MED   73%     HIGH 100%     HIGH 100%
KAVL       HIGH  92%     HIGH  82%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     MED   78%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     MED   73%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     MED   78%     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...CDG
NEAR TERM...PM
SHORT TERM...CDG
LONG TERM...CDG
AVIATION...PM


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