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 211844
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
244 PM EDT TUE OCT 21 2014

.SYNOPSIS...
NORTHWEST FLOW WILL KEEPS CLOUDS AND ISOLATED SHOWERS ACROSS THE
NORTH CAROLINA MOUNTAINS TONIGHT...WITH DRY CONDITIONS ELSEHWERE.
HIGH PRESSURE RETURNS FOR THE REST OF THE WEEK AND CONTINUES INTO
THE THE WEEKEND.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
AS OF 240 PM EDT TUESDAY...HIGH AMPLITUDE UPPER TROF CONTINUES TO
SWING THROUGH THE EAST/CENTRAL GREAT LAKES REGION.  MEANWHILE AT THE
SURFACE...A WEAK CYCLONE SLIDING SOUTHEAST INTO THE MIDATLANTIC
PUSHES A COLD FRONT SOUTHWARD ACROSS WESTERN NC AND INTO PORTIONS OF
NORTHEAST GA AND THE WESTERN UPSTATE.  HIGH PRESSURE BUILDING TO THE
WEST WILL CONTINUE PUSHING EAST EFFECTIVELY INCREASING PRESSURE
GRADIENT FORCES ACROSS THE ENTIRE FORECAST AREA THIS AFTERNOON. THIS
COMBINED WITH A DEEPENING MIXED LAYER WILL YIELD GUSTY CONDITIONS
THROUGH THE REMAINDER OF THE AFTERNOON BEFORE SUBSIDING AFTER
SUNSET.  THAT SAID...CHANNELING EFFECTS AND CONTINUED MODERATE NW
FLOW ALOFT WILL YIELD PERSISTENT GUSTS THROUGH THE THE OVERNIGHT
ACROSS THE WESTERN NC MOUNTAINS.  AS FOR PRECIP CHANCES...CARRIED
EARLIER FORECAST ISOLATED POPS ACROSS THE NORTHERN MOUNTAINS THIS
EVENING/OVERNIGHT DUE TO WEAK UPSLOPE FLOW POTENTIAL.  MOISTURE WILL
LIKELY REMAIN TRAPPED BENEATH A DEVELOPING INVERSION OVERNIGHT
ALLOWING FOR MOUNTAIN VALLEY STRATUS FORMATION.  CONDITIONS WILL
IMPROVE ON WEDNESDAY AS THE PRESSURE GRADIENT SLOWLY RELAXES AND
UPPER TROF EJECTS TO THE EAST.  ABOVE MENTIONED HIGH PRESSURE WILL
CONTINUE ADVECTING OVERHEAD WITH UPPER HEIGHTS ALSO RISING LEADING
TO A DRY FORECAST.  DESPITE THE FROPA AND WEAK COLD ADVECTION
PATTERN...NOT EXPECTING TEMPERATURES TO COOL SUBSTANTIALLY.  HOWEVER
FORECAST DOES FEATURE BOTH MAX/MIN TEMPERATURES THROUGH THE PERIOD A
FEW DEGREES BELOW NORMAL.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
AS OF 205 PM EDT TUESDAY...THE DEEP UPPER LOW ALONG THE MID-ATLANTIC
COAST WILL MOVE NORTHEAST ALLOWING SHORT WAVE RIDGING TO DEVELOP OVER
THE SE STATES ON THU. A SHORT WAVE OVER THE NORTHERN PLAINS IS
FORECAST TO DIVE QUICKLY SE AND MOVE INTO THE MID-ATLANTIC STATES
LATE FRIDAY. THE 12Z GFS HAS TRENDED FASTER...FARTHER NORTH AND LESS
AMPLIFIED WITH THE UPPER WAVE FOR FRIDAY AS OPPOSED TO THE 00Z EC
AND NOW THE 12Z CMC WHICH ARE SLOWER AND CLOSE OFF AN UPPER LOW OVER
THE OHIO VALLEY. THE ONLY ISSUE WITH THIS SYSTEM IS WHETHER THE
UPPER FORCING AND NW UPSLOPE FLOW WILL BE ENOUGH TO SQEEZE OUT ANY
LIGHT SHOWERS OVER THE NORTHERN MOUNTAINS FRIDAY AFTERNOON. THE 12Z
GFS/NAM SUPPORT MAINTAINING A DRY FORECAST FOR THE MOUNTAINS ON
FRIDAY WITH PERHAPS JUST SOME MID-HIGH LEVEL CLOUDINESS. HENCE...
WILL KEEP MENTIONALB EPOPS OUT OF THE FORECAST.

BACKING UP IN TIME...WITH THE DEAMPLIFYING FLOW AND RISING HEIGHTS
OVER THE REGION ON THURSDAY...TEMPS SHOULD REBOUND BUT STILL REMAIN
SHY OF CLIMO. WED NIGHT WILL BE A CHILLY WITH MID 30S COMMON OVER
THE MOUNTAINS AND EVEN SOME POCKETS OF UPPER 30S POSSIBLE IN
PIEDMONT. POCKETS OF FREEZING TEMPS ARE LIKELY IN THE LITTLE TN
VALLEY WHERE THE FROST/FREEZE PROGRAM HAS ENDED. WINDS ESPECIALLY IN
THE CENTRAL/NORTHERN MOUNTAINS LOOK TO STAY HIGH ENOUGH TO PRECLUDE
WIDESPREAD FROST FORMATION AND FREEZING TEMPS. MAX TEMPS ON FRIDAY
ARE FORECAST TO WARM A COUPLE MORE DEGREES IN THE DOWNSLOPE FLOW.
DEEP LAYERED DRY AIR SHOULD ALLOW FOR GENERALLY CLEAR CONDITIONS WED
NIGHT THROUGH THU NIGHT...WITH SOME JUST PATCHY HIGH CLOUDS ON
FRIDAY AHEAD THE UPPER WAVE.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
AS OF 205 PM TUESDAY...GUIDANCE IN GENERAL AGREEMENT FOR THE MEDIUM
RANGE. AN UPPER TROF CROSSES THE AREA FRI NITE LEAVING NW FLOW OVER
THE AREA THRU SUN. UPPER RIDGE BUILDS INTO THE AREA MON...THEN RIDGE
AXIS SLIDES EAST ON TUE...WITH NEXT POTENTIAL WX SYSTEM REMAINING
WEST OF THE AREA UNTIL AFTER THIS PERIOD. CANNOT RULE OUT SOME SHRA
ACROSS THE MTNS SAT NITE AS THE TROF MOVES THRU...BUT GUIDANCE BLEND
KEEPS FCST DRY. A DRY COLD FRONT BRUSHES THE AREA SAT NITE...THEN
HIGH PRESSURE BUILDS IN SUN AND SLOWLY SLIDES EAST MON AND TUE. NEAR
NORMAL TEMPS ON SAT RISE A LITTLE ABOVE NORMAL THRU THE PERIOD...
WHILE LOWS START OUT A LITTLE BELOW NORMAL AND RISE TO A LITTLE
ABOVE NORMAL THRU THE PERIOD.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
AT KCLT...VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD.  DRY COLD
FRONT WILL SLIDE THROUGH THE REGION THIS AFTERNOON LEADING TO
INCREASING LOW LEVEL CLOUDINESS ACROSS THE NC PIEDMONT.
LIKEWISE...INCREASING PRESSURE GRADIENT AND DEEPENED MIXED LAYER
WILL YIELD GUSTY NORTHWESTERLY VEERING FLOW AT THE SURFACE.
THUS...INITIALIZED TAF WITH WNW WINDS AT 06KTS UNDER FEW LOW CU AND
HIGH LEVEL CIRRUS.  INCREASED SKY BY MID AFTERNOON TO SCT LEVELS
WITH A 4HR TEMPO FOR BKN045 CIGS.  CONDITIONS IMPROVE BEHIND THE
FRONT THIS EVENING WITH SKIES SCT TO SKC WITH GUSTY WINDS GIVING WAY
TO SUSTAINED 6-10KT NW FLOW.

ELSEWHERE...MUCH THE SAME AS KCLT ABOVE AS VFR CONDITIONS WILL
PREVAIL AT ALL SITES WITH THE POSSIBLE EXCEPTION OF IFR/MVFR CIGS
OVERNIGHT AT KAVL.  ALL SITES WERE INITIALIZED WITH GUSTY WNW WINDS
AS THE WEAK/DRY COLD FRONT SLIDES THROUGH THE REGION.  FEW/SCT LOW
LEVEL CU IS FEATURED FOR SKIES AT ALL SITES THROUGH THE AFTERNOON
WITH IMPROVEMENT FORECAST BY 00Z ASIDE FOR AT KAVL.  AS FOR
KAVL...MOISTURE POOLING ALONG THE TERRAIN AMONGST NW FLOW PATTERN
WILL LIKELY BECOME TRAPPED BENEATH THE DEVELOPING INVERSION LEADING
TO POSSIBLE MOUNTAIN VALLEY STRATUS OVERNIGHT.  A FEW GUIDANCE
SOURCES WERE HINTING AT POSSIBLE IFR CONDITIONS...HOWEVER HELD CIGS
AT LOW MVFR FOR THIS TAF ISSUANCE THROUGH MORNING.  GUSTY WINDS WILL
SUBSIDE WITH 6-10KT NW FLOW PREVAILING THROUGH THE OVERNIGHT AT ALL
SITES EXCEPT FOR KAVL WHERE CHANNELING YIELDS CONTINUED 20-25KT
GUSTS THROUGH THE REMAINDER OF THE TAF CYCLE.

OUTLOOK...BLUSTERY AND COOLER FOR THE MIDDLE PART OF THE WEEK...THEN
WARMING BY WEEKS END INTO THE WEEKEND AS DEEP LAYER RIDGING SETTLES
IN.

CONFIDENCE TABLE...

            18-24Z        00-06Z        06-12Z        12-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH  81%     HIGH  83%
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...RWH
NEAR TERM...CDG
SHORT TERM...LG
LONG TERM...RWH
AVIATION...CDG






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