Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 281443
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
943 AM EST WED JAN 28 2015

.SYNOPSIS...
DRY HIGH PRESSURE WILL REMAIN ACROSS THE REGION THROUGH TODAY. ON
THURSDAY...A COLD FRONT WILL CROSS THE FORECAST AREA WITH ANOTHER
HIGH PRESSURE SYSTEM BUILDING IN FRIDAY THROUGH SATURDAY. A MOIST
LOW PRESSURE SYSTEM IS EXPECTED TO AFFECT THE REGION ON SUNDAY INTO
MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 935 AM EST WEDNESDAY...OTHER THAN A FEW LOW CLOUDS ALONG THE
HIGHEST PEAKS AND RIDGETOPS OF WESTERN NC...CLEAR SKIES PREVAIL
REGIONWIDE THIS MORNING.  INCREASING INSOLATION AND MODERATE
DOWNSLOPING FLOW ARE ALREADY ALLOWING TEMPERATURES TO WARM INTO THE
LOWER TO MID 30S.  WINDS REMAIN SLIGHTLY ELEVATED ACROSS PORTIONS OF
THE BLUERIDGE THUS BLENDED IN LATEST MAV AND RECALCULATED GUSTS TO
BETTER ALIGN WITH RECENT OBS.  RH LEVELS ARE STILL FCST TO FALL TO
CRITICAL LEVELS THIS AFTERNOON HOWEVER WINDS SHOULD REMAIN BELOW ANY
FIRE DANGER CRITERIA.  OTHERWISE...CURRENT FCST REMAINS ON TRACK AND
ASIDE FOR MINOR TWEAKS TO TEMPERATURES AND DEWPOINTS...NO OTHER
CHANGES NEEDED/MADE WITH THIS UPDATE.

PREVIOUS DISCUSSION...

1115 UTC UPDATE...SKY COVER HAS BEEN ADJUSTED FROM INFRARED SATELLITE
IMAGERY. WINDS WERE UPDATED TO INCORPORATE THE LATEST NAM GUIDANCE.

AT 230 AM EST WEDNESDAY...AN UPPER TROUGH WILL PROGRESS OFF THE EAST
COAST TODAY AND TONIGHT...WHILE A LOW AMPLITUDE RIDGE CROSSES THE MS
RIVER VALLEY AND THE SOUTHERN APPALACHIANS. AN UPPER TROUGH
AMPLIFIES OVER THE MS RIVER VALLEY TONIGHT...WHILE A SHORTWAVE
MOVES THROUGH ITS BASES.

A DRY SURFACE RIDGE NOW OVER THE GREAT LAKES AND TN RIVER VALLEY
WILL SLOWLY CROSS THE APPALACHIANS TODAY...RESULTING IN RELAXED
PRESSURE GRADIENT AND LIGHTER WINDS. THE RIDGE MOVES TO THE EAST
COAST OVERNIGHT...WHILE WINDS VEER FROM N TO S AHEAD OF AND
APPROACHING COLD FRONT IN THE MS RIVER VALLEY. MID AND UPPER LEVEL
MOISTURE AHEAD OF THIS FRONT WILL REACH OUR AREA OVERNIGHT...BUT LOW
LEVEL MOISTURE DOES NOT...AND NO POPS WILL BE CARRIED. TEMPERATURES
TODAY AND TONIGHT WILL RUN SLIGHTLY BELOW NORMAL IN THE COOL AIR
MASS CROSSING OUR AREA.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 310 AM WEDNESDAY...PRECIPITATION CHANCES WILL GRADUALLY
INCREASE THROUGHOUT THURSDAY...MAINLY ACROSS THE MTNS...AS SHORT
WAVE TROUGH(S) AND ATTENDANT COLD FRONT APPROACH THE REGION FROM THE
OHIO VALLEY. THE BULK OF THE MOISTURE ASSOCIATED WITH THIS SYSTEM
WILL BE POST-FRONTAL. THUS...WHILE I WOULD NOT RULE OUT A
DIMINISHING AREA OF LIGHT PRECIP IN THE WARM-SECTOR DURING THE DAY
THU (JUSTIFYING SLT/LOW CHANCE POPS...MAINLY ACROSS THE MTNS)...IT
APPEARS THE HIGHEST POPS ACROSS THE AREA WILL HOLD OFF UNTIL AFTER
FROPA...WHEN A DECENT SETUP FOR ACCUMULATING NORTHWEST FLOW SNOW
WILL BECOME ESTABLISHED FROM LATE THU EVENING INTO EARLY FRIDAY.
WHILE 2-4 INCHES OF SNOW APPEARS POSSIBLE DURING THIS TIME IN THE
USUAL SUSPECT AREAS...THE PRIMARY ISSUE WITHIN THE COLD ADVECTION
REGIME IS THE POTENTIAL FOR STRONG WINDS ACROSS THE MTNS. THE
PATTERN IS FAVORABLE FOR AT LEAST AN ADVISORY LEVEL EVENT ACROSS THE
HIGH TERRAIN...WITH A SURFACE LOW PASSING OVER THE EASTERN GREAT
LAKES INTO THE NORTHEAST CONUS...H8 WINDS OF 40-50 KTS...AND ABOUT A
6 MB PRESSURE GRADIENT PROGGED BETWEEN THE GREAT TENN VALLEY AND THE
NC FOOTHILLS. HOWEVER...BASED UPON WHAT I/M SEEING THUS FAR...I
WOULD LEAN STRONGLY TOWARD THE ADVISORY END OF THE SPECTRUM FOR NOW.

THE REMAINDER OF THE LATE WEEK PERIOD WILL SEE CLEARING SKIES ACROSS
THE MTNS...WITH CONTINUED CLEAR/MOSTLY CLEAR SKIES ACROSS THE
PIEDMONT AND FOOTHILLS. TEMPS WILL BE NEAR TO SLIGHTLY BELOW CLIMO
AS UPPER HEIGHTS REMAIN RELATIVELY LOW IN ASSOCIATION WITH A
PROGRESSIVE UPPER TROUGH.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 325 AM...A PATTERN CHANGE IS STILL IN THE OFFING FOR THE EARLY
PART OF THE MEDIUM RANGE...AS A ROCKIES TROUGH/SOUTHWEST CONUS UPPER
LOW FORCE HEIGHT RISES ALONG THE EAST COAST...WITH LOW AMPLITUDE
RIDGING EXPECTED BY SUNDAY. AS THE TROUGH EJECTS OVER THE PLAINS...
CYCLOGENESIS WILL OCCUR IN THE VICINITY OF THE ARKLATEX BY EARLY
SUNDAY...WHILE WILL QUICKLY TAP INTO AN ABUNDANCE OF GULF MOISTURE.
WHILE PREVIOUS GFS GUIDANCE WAS A BIT MORE INTERESTING FOR OUR AREA
(WINTER-WX WISE) LATE IN THE WEEKEND...WITH THE SURFACE LOW TRACKING
ACROSS THE HEART OF THE FORECAST AREA...THE 00Z RUN ONCE AGAIN
FEATURES A WEST-OF-THE-APPALACHIANS SOLUTION...VERY SIMILAR TO THE
ECMWF AND CANADIAN GUIDANCE. THIS PATTERN WOULD BE MOST UNFAVORABLE
FOR ANYTHING OTHER THAN PERHAPS A BRIEF PERIOD OF MOUNTAIN FREEZING
RAIN...AND THAT/S ONLY IF THE PRECIP WERE TO BEGIN EARLY ENOUGH
SUNDAY AM. IN FACT...THIS MAY BE DEVELOPING INTO MORE OF A POTENTIAL
HEAVY RAIN MAKER...AND PERHAPS EVEN A HIGH SHEAR/LOW CAPE SEVERE
CONVECTION CONCERN...AS SHEAR PARAMETERS SHOULD BE QUITE FAVORABLE
WITHIN THE WARM SECTOR OF A DEEPENING CYCLONE SUNDAY NIGHT/EARLY
MONDAY.

HAVING SAID THAT...WITH THE GFS STILL WAFFLING A BIT...OPTED TO NOT
MAKE ANY BOLD CHANGES TO THE FORECAST ATTM...BUT THE DAY SHIFT WILL
NEED TO ENTERTAIN REMOVING THE BULK OF ANY WINTER WEATHER POTENTIAL
FROM THE WEEKEND FORECAST. AFTER POSSIBLY ANOTHER MOUNTAIN WIND/SNOW
EVENT MON NIGHT...DRY WEATHER WILL RETURN BY THE END OF THE PERIOD.

&&

.AVIATION /15Z WEDNESDAY THROUGH SUNDAY/...
AT KCLT...VFR. LIGHT N WINDS WILL PERSIST THROUGH THIS AFTERNOON...
THEN VEER TO SE THIS EVENING AS HIGH PRESSURE SHIFTS TO THE EAST AND
A COLD FRONT CROSSES THE MS RIVER VALLEY. THE AIR MASS WILL BE TOO
DRY FOR FOG RELATED VSBY RESTRICTIONS...AND UPPER LEVEL CLOUDS AHEAD
OF THE FRONT SHOULD BE INSUFFICIENT FOR A HIGH LEVEL CIG.

ELSEWHERE...VFR. WINDS FROM THE NNW WILL PERSIST THIS MORNING. WINDS
WILL GO SOUTH THIS EVENING ON THE BACK SIDE OF DEPARTING HIGH
PRESSURE...WHILE A COLD FRONT CROSSES THE MS RIVER. HIGH CLOUDS MOVE
AHEAD OF THE FRONT WILL ARRIVE TONIGHT...BUT NOT IN SUFFICIENT
QUANTITIES FOR A CIG. ALTHOUGH LOWER ATMOSPHERE WILL START TO
MOISTURE SLIGHTLY...IT WILL REMAIN TOO DRY FOR FOG RELATED VSBY
RESTRICTIONS.

OUTLOOK...A PAIR OF CLIPPER SYSTEMS WILL BRING CHANCES FOR RAIN OR
SNOW SHOWERS TO THE NC MTNS THU AND FRI. MOST OF THESE SHOWERS WILL
REMAIN WEST AND NORTH OF KAVL...BUT BRIEF PERIODS OF RESTRICTIONS
CANNOT BE RULED OUT. OTHERWISE...MAINLY VFR CONDITIONS ARE EXPECTED
ACROSS THE AREA UNTIL MOISTURE BEGINS TO RETURN SUNDAY.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
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: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

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

&&

$$
SYNOPSIS...SBK
NEAR TERM...CDG/JAT
SHORT TERM...JDL
LONG TERM...JDL
AVIATION...JAT



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