Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 021800
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
100 PM EST MON MAR 2 2015

.SYNOPSIS...
COOL CANADIAN HIGH PRESSURE WILL BUILD INTO THE REGION THROUGH
TUESDAY...BUT MOIST AND MILDER AIR SHOULD BE BACK ON WEDNESDAY OUT
AHEAD AN APPROACHING COLD FRONT. THIS FRONT IS FORECAST TO PASS
THROUGH THE AREA ON THURSDAY...DRYING US OUT BY THURSDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 PM...THE FOG IS LONG GONE...AND THE SKY HAS CLEARED
ACROSS ALL BUT A REMNANT OF LOW CLOUDS OVER THE SRN PART OF THE
CHARLOTTE METRO AREA. THE PROBLEM NOW IS THAT WE ARE MUCH CLEARER
THAN EXPECTED OUTSIDE OF THE MTNS...WHICH HAS ALLOWED TEMPS TO RACE
UPWARD A FEW CATEGORIES ABOVE GUIDANCE IN SOME PLACES. THE MAX TEMPS
HAVE ALSO BEEN EXCEEDED BY MORE THAN TEN DEGREES OVER PARTS OF THE
NRN FOOTHILLS AND NW PIEDMONT...AS THE BACK DOOR FRONT HAS YET TO
ARRIVE. WILL HAVE TO MAKE A SIGNIFICANT UPWARD ADJUSTMENT IN THOSE
AREAS...AND ALSO A LARGE CHUNK OF THE UPSTATE AND NE GEORGIA WHICH
CLEARED OUT MUCH FASTER THAN PREVIOUSLY THOUGHT. NO PRECIP YET.

REMAINDER OF PREVIOUS DISCUSSION...

OTHERWISE...WITH THE QUASI-ZONAL STATE OF THE MID-LEVEL FLOW...COLD
ADVECTION WILL BE DELAYED ACROSS MOST AREAS OUTSIDE THE MTNS...UNTIL
SURFACE HIGH PRESSURE EXPANDS ACROSS THE CENTRAL APPALACHIANS AND
MID-ATLANTIC LATER TODAY. THIS WILL RESULT IN A BACKDOOR COLD
FRONT/COLD AIR DAMMING REGIME DEVELOPING GRADUALLY FROM NORTHEAST TO
SOUTHWEST ACROSS THE CWA THIS AFTERNOON THROUGH TONIGHT. AS
SUCH...THERE WILL BE QUITE THE TEMP GRADIENT ACROSS THE AREA THIS
AFTERNOON...WITH HIGHS RANGING FROM THE LOWER TO MID-40S ACROSS THE
MTN VALLEYS OF NORTHWEST NC...TO THE LOWER 50S ACROSS THE NORTHWEST
PIEDMONT...TO 65-70 ACROSS THE LOWER SC PIEDMONT.

WARM FRONT ACTIVATION IS EXPECTED TO OCCUR QUICKLY ACROSS THE
SOUTHEAST LATER TODAY INTO TONIGHT...AS A CYCLONE CROSSES THE
CENTRAL CONUS. UPGLIDE PRECIPITATION IS EXPECTED TO EXPAND INTO THE
FORECAST AREA THIS EVENING...WITH LIKELY POPS WARRANTED ACROSS
ROUGHLY THE SOUTHWEST HALF OF THE AREA TONIGHT. WITH TEMPS EXPECTED
TO FALL BELOW FREEZING ACROSS PORTIONS OF THE NORTHERN BLUE RIDGE...
SOME FREEZING RAIN WILL BE POSSIBLE TOWARD DAYBREAK ACROSS PORTIONS
OF THE NORTHERN NC MTNS AND FOOTHILLS. HOWEVER...IT IS NO SURE THING
THAT PRECIP WILL EXPAND THAT FAR NORTH...AND IF IT DOES QPF WILL BE
VERY LIGHT...WITH THE BULK OF RAINFALL EXPECTED TO FOCUS CLOSER TO
THE CAD FRONT ACROSS SOUTHERN PIEDMONT AREAS AND THE SC MIDLANDS.
THEREFORE...NO HEADLINES FOR FREEZING RAIN WILL BE ENTERTAINED ATTM.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
300 AM EST MONDAY...ON TUESDAY MORNING A POSITIVELY TILTED UPPER
TROUGH WILL EXTEND FROM HUDSON BAY TO NW MEXICO. THE TROUGHS TILT
BECOMES MORE POSITIVELY BY THURSDAY AS THE NORTHERN PORTION PROGRESSES
INTO EASTERN CANADA...WHILE THE SOUTHERN PORTION REMAINS OVER NW
MEXICO AND THE SW USA.

AT THE SURFACE...COOL HIGH PRESSURE WILL BE LODGED ALONG THE EASTERN
SEABOARD ON TUESDAY...WITH MOISTURE ISENTROPIC UPGLIDE OVER A FRONT IN
S GA PRODUCING WIDESPREAD PRECIPITATION OVER NE GA AND THE WESTERN
CAROLINAS. AT THIS POINT IT APPEAR THAT THIS WILL BE MOSTLY A RAIN
EVENT...AS THE COLDEST PART OF THE RIDGE WILL BE WELL N OF OUT AREA.
AN EXCEPTION MIGHT BE IN THE NORTHERN NC MOUNTAINS EARLY IN THE DAY.
THE SURFACE RIDGE MOVES OFFSHORE LATE TUESDAY WHILE A COLD FRONT
CROSSES THE OH AND MID MS RIVER VALLEY. THIS FRONT SLOWLY CROSSES
OUR AREA ON WEDNESDAY...FINALLY MOVING SW OF THE AREA ON WEDNESDAY
NIGHT. INSTABILITY WILL BE PRESENT AHEAD OF THE FRONT...POSSIBLE
SUPPORTING A FEW THUNDERSTORMS ON WEDNESDAY. CAPE AND SHEAR DO NOT
APPEAR TO COME INTO GOOD ALIGNMENT AT THIS TIME. BEHIND THE
FRONT...COLD ADVECTION WILL SUPPORT A CHANGEOVER TO SNOW IN THE NC
MOUNTAINS WEDNESDAY NIGHT.

THE HIGH TEMPERATURE TUESDAY WILL RUN AROUND 17 DEGREES BELOW NORMAL
IN COLD AIR DAMMING ON TUESDAY...AND THE MINIMUM TEMPERATURE AROUND
5 DEGREE ABOVE NORMAL UNDER CLOUD COVER WITH WARM ADVECTION SETTING UP
AHEAD OF THE FRONT. TEMPERATURES WEDNESDAY AND WEDNESDAY NIGHT WILL
BE AROUND 5 DEGREE ABOVE NORMAL...IN WARM ADVECTION AHEAD OF THE
FRONT...AND LINGERING CLOUD COVER ITS WAKE.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AT 300 AM EST MONDAY...ON THURSDAY MORNING A POSITIVELY TILTED UPPER
TROUGH WILL EXTEND FROM EASTERN CANADA TO NW MEXICO...WHILE A FLAT
RIDGE WILL BE CENTERED OVER THE BAHAMAS. BY FRIDAY MORNING THE
NORTHERN STREAM TROUGH PROGRESSES...ORPHANING AN UPPER LOW OVER NW
MEXICO AND THE SW USA. THE EASTERN TROUGH AMPLIFIES INTO SATURDAY...
THOUGH STILL REMAINING BROAD...WHILE THE UPPER LOW REMAINS IN NW
MEXICO. BY SUNDAY THE UPPER LOW FILLS AND THE REMAINING TROUGH
PROGRESSES OVER THE SOUTHERN PLAINS. SHORTWAVES ROUNDING THE EASTERN
TROUGH RESULTING IN SOME AMPLIFICATION EARLY MONDAY...THOUGH THE
MODELS DIVERGE ON THE TIMING OF THESE FEATURES.

AT THE SURFACE...ON THURSDAY A COLD FRONT WILL BE DEPARTING THE
AREA....WITH A TIGHT PRESSURE GRADIENT IN ITS WAKE KEEPING MOIST
UPSLOPE FLOW GOING INTO THE NC MOUNTAINS BORDERING TN. BY FRIDAY
HIGH PRESSURE SETTLE OVER THE CENTRAL APPALACHIANS...AND THE
PRESSURE GRADIENT RELAXES OVER OUR AREA. ON SATURDAY THE HIGH
SETTLES SOUTH OVER THE CAROLINAS AND GA. ANOTHER COLD FRONT RAPIDLY
CROSSES THE AREA SATURDAY NIGHT....FOLLOWED BY ANOTHER ROUND OF HIGH
PRESSURE ON SUNDAY. THERE ARE SOME INDICATIONS THAT MOISTURE MAY
SPREAD NORTH OVER THIS HIGH ON SUNDAY...BUT CONFIDENCE IS LACKING.

TEMPERATURES WILL RUN AROUND 15 DEGREES BELOW NORMAL IN COLD
ADVECTION BEHIND THE FIRST FRONT ON THURSDAY AND FRIDAY...WARMING TO
AROUND 5 DEGREES BELOW NORMAL AHEAD OF AND IMMEDIATELY BEHIND THE
SECOND FRONT ON SATURDAY AND SUNDAY.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
AT KCLT...VFR EXPECTED INTO THE MIDDLE PART OF THE EVENING. THINK
LOW CLOUDS WILL DEVELOP THIS AFTERNOON WITH BASES IN THE 035-050
RANGE...WHICH COULD BRING A TEMPORARY CEILING. A WEST WIND AT THE
MOMENT IS MOST LIKELY TO COME AROUND TO NW OR N. THE SITUATION
SHOULD GO DOWNHILL THIS EVENING AS LOW LEVEL MOISTURE RETURNS ALONG
WITH ISENTROPIC LIFT ABOVE A BACK DOOR COLD FRONT EXPECTED TO SLIP
THROUGH FROM THE NE DURING THE EARLY EVENING. EXPECT AN MVFR CEILING
TO DEVELOP NO LATER THAN 03Z...WHICH WILL EVENTUALLY LOWER TO IFR AS
LIGHT PRECIP DEVELOPS AND UPGLIDE INCREASES IN THE PRE-DAWN HOURS.
WINDS SHOULD BE NE FROM EARLY EVENING THROUGH THE END OF THE TAF
PERIOD. THERE SHOULD BE SOME IMPROVEMENT TO CEILINGS...INTO THE
LOWER PART OF MVFR...AROUND MID MORNING ON TUESDAY AS THE BOUNDARY
LAYER WARMS.

ELSEWHERE...AN MVFR CEILING AT KAVL SHOULD BREAK UP DURING THE EARLY
TO MID AFTERNOON. AFTER THAT...THE FCST WILL PROCEED SIMILAR TO KCLT
WITH SOME MINOR TIMING DIFFERENCES. THE BACK DOOR FRONT SHOULD DROP
DOWN TO THE S/SW ACROSS THE REGION IN THE EARLY TO MID EVENING...
BRINGING THE WIND AROUND TO THE N/NE. CLOUDS DEVELOP IN THE MID
EVENING AS THE FRONT GOES THROUGH...FIRST MVFR AND THEN IFR. A
CONCERN WILL BE TEMPS IN THE PRE-DAWN THRU DAYBREAK HOURS. AT THIS
TIME...IT APPEARS THAT ONLY KHKY HAS A CHANCE AT ANY FREEZING
RAIN...AND THAT CHANCE SHOULD BE SMALL AS THE MAIN POTENTIAL IS
ACTUALLY CLOSER TO THE BLUE RIDGE.

OUTLOOK...LOW CIGS AND LIGHT PRECIP/DRIZZLE WILL BE LIKELY ACROSS
MUCH OF THE AREA IN TUESDAY AFTERNOON AND EVENING. A COLD FRONT WILL
MOVE SLOWLY THROUGH THE REGION WED THROUGH THURSDAY...BRINGING
CHANCES FOR HEAVIER RAINFALL TO THE AREA. FRIDAY AND SATURDAY LOOK
VFR.

CONFIDENCE TABLE...

            13-19Z        19-01Z        01-07Z        07-12Z
KCLT       HIGH  95%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   74%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       MED   77%     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...JAT
NEAR TERM...JDL/PM
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...PM



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