Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 031446
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
946 AM EST TUE MAR 3 2015

.SYNOPSIS...
COOL CANADIAN HIGH PRESSURE WILL BUILD INTO THE REGION TODAY... BUT
MOIST AND MILDER AIR SHOULD BE BACK ON WEDNESDAY AHEAD OF AN
APPROACHING COLD FRONT. THIS FRONT IS FORECAST TO PASS THROUGH THE
AREA ON THURSDAY...WITH COLD AND DRY HIGH PRESSURE RETURNING FOR
FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 915 AM...HAVE CANCELLED THE FREEZING RAIN ADVISORY EARLY AS
TEMPS WERE ABOVE 32F AND EXPECTED TO REMAIN AS SUCH...AND RADAR
COVERAGE IS UNIMPRESSIVE AT BEST. COVERAGE SHOULD INCREASE LATER IN
THE DAY ACROSS THE NRN TIER BUT TEMPS WILL BE ABOVE FREEZING.
ELSEWHERE...HAVE MADE SOME ADJUSTMENTS TO THE PRECIP CHANCES TO THE
SOUTH BASED ON RADAR TRENDS. TEMPS WILL REMAIN STEADY IN PLACES
WHERE DIABATIC COOLING CAN OFFSET DIURNAL WARMING...AND TEMPS COULD
FALL INTO THE AFTERNOON IF PRECIP BECOMES MORE WIDESPREAD.

PREVIOUS DISCUSSION...

OTHERWISE...MAX TEMPS WILL OCCUR AT 12Z AT MOST LOCATIONS DUE TO
DEVELOPING COLD AIR DAMMING. THE ONLY EXCEPTION WILL BE THE FAR
WESTERN MTN VALLEYS NEAR THE TENN BORDER...WHICH MAY WELL WARM INTO
THE 60S THIS AFTERNOON. MEANWHILE...MUCH OF THE PIEDMONT WILL REMAIN
STEADY...OR SLOWLY DROP INTO THE 40S AND UPPER 30S BY THIS
AFTERNOON.

POPS WILL GRADUALLY DIMINISH FROM SOUTH TO NORTH THIS AFTERNOON INTO
THIS EVENING...AS THE MOISTURE DEPTH DECREASES...THE BEST UPGLIDE
SHIFTS TOWARD THE MID-ATLANTIC... AND THE WEDGE BEGINS ITS GRADUAL
EROSION PROCESS. IN FACT...TEMPERATURES SHOULD WARM...AT LEAST
SLOWLY...THROUGH THE OVERNIGHT....LIKELY RETURNING TO THE 40S AND
50S BY DAYBREAK WED.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
AT 300 AM EST TUESDAY...ON WEDNESDAY MORNING AN UPPER TROUGH WILL
EXTEND FROM HUDSON BAY TO NW MEXICO...WHILE AN UPPER RIDGE OVER THE
WESTER CARIBBEAN EXTENDS N OF THE EAST COAST OF THE USA. BY THURSDAY
THE NORTHERN PORTION OF THE UPPER TROUGH WILL HAVE PROGRESSES INTO
EASTERN CANADA. A STRONG SHORTWAVE WILL MOVE THROUGH THE TROUGH FROM
THE MS RIVER VALLEY TO THE UPPER OH RIVER VALLEY DURING THE
DAY...CROSSING THE SOUTHERN APPALACHIANS BY EARLY EVENING.

AT THE SURFACE...ON WEDNESDAY A SLOW MOVING COLD FRONT WILL REACH
THE SOUTHERN APPALACHIANS BY MIDDAY...MOVING SOUTHEAST TO THE BLUE
RIDGE BY EVENING. THE FRONT REACHES THE INTERSTATE 85 CORRIDOR IN
THE MIDDLE OF THE NIGHT... ALTHOUGH MODERATE SHEAR WILL BE
PRESENT...ONLY MODEST INSTABILITY ALONG THE BOUNDARY APPEARS TO
SUPPORT JUST A FEW  THUNDERSTORMS OVERNIGHT. THE FRONT FINALLY MOVES
EAST OF OUR ARE BY DAYBREAK TUESDAY. TEMPERATURES WILL RUN ABOVE
NORMAL AHEAD OF THE FRONT...FALLING BELOW NORMAL IN ITS WAKE.

EXTENSIVE MOISTURE BEHIND THE BOUNDARY WILL SUPPORT PRECIPITATION IN
ITS WAKE THROUGH ACROSS THE FOOTHILLS AND PIEDMONT FOR MUCH OF THE
DAY ON THURSDAY...WHILE COLD NW FLOW RESULTS IN A CHANGEOVER TO SNOW
SHOWERS IN THE NC MOUNTAINS. ON THURSDAY NIGHT THE FRONT MOVES FAR
ENOUGH SE TO END PRECIPITATION EAST OF THE MOUNTAINS...AND MOISTURE
DIMINISHES ALONG THE TN BORDER...RESULTING IN AND END TO SNOW SHOWERS
THERE.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
AT 300 AM EST TUESDAY...ON FRIDAY MORNING A BROAD UPPER TROUGH WILL
EXTEND FROM A CLOSED LOW IN THE CANADIAN ARCTIC TO THE EASTER USA.
MEANWHILE AN UPPER LOW WILL BE OVER NW MEXICO... AND A FLAT RIDGE
WILL BE OVER THE CARIBBEAN. THIS PATTERN REMAINS THROUGH SATURDAY.
BY SUNDAY THE MEXICAN UPPER LOW FILLS AND STARTS TO MOVE INTO THE
BASED OF THE UPPER TROUGH. ON MONDAY SHORTWAVE ENERGY MOVING THROUGH
THE UPPER TROUGH RESULTS IN AMPLIFICATION OVER THE EASTERN USA.

AT THE SURFACE...ON FRIDAY MORNING HIGH PRESSURE CENTERED OVER THE
OH RIVER VALLEY WILL EXTEND FROM NY TO TX. A COLD FRONT WILL BE OVER
S FL. MOISTURE N OF THE FRONT IS EXPECTED TO BE SUFFICIENTLY FAR
ENOUGH S TO KEEP PRECIPITATION OUT OF OUR AREA. THE SURFACE HIGH
SETTLES FARTHER SOUTH ON SATURDAY...EXTENDING FROM NC TO TX...WHILE
THE FRONT REMAINS IN S FL...AGAIN WITH ITS ASSOCIATED MOISTURE S OF
OUR AREA. A COLD FRONT DROPS QUICKLY S ACROSS OUR AREA ON SATURDAY
NIGHT...REACHING S GA BY SUNDAY MORNING...APPROACHING THE FIRST FRONT
IN FL...WHILE ANOTHER SURFACE HIGH MOVES ACROSS THE OH RIVER VALLEY.
ON MONDAY THE SECOND SURFACE HIGH REACHES THE SOUTHEAST...WHILE A
STATIONARY FRONT REMAINS IN S FL. THERE ARE SOME INDICATIONS THAT
MOISTURE WILL SPREAD NORTH OVER THE FL FRONT TOWARDS OUR AREA EARLY
NEXT WEEK S AS SURFACE WAVE DEVELOPS IN THE GULF OF MEXICO.
CONFIDENCE IS LOW AT THIS POINT...BUT IT APPEARS THAT ANY WINTER
PRECIPITATION WOULD BE CONFINED TO THE MOUNTAINS ON SUNDAY NIGHT.

TEMPERATURES WILL AROUND AROUND 15 DEGREE BELOW NORMAL ON FRIDAY IN
COLD HIGH PRESSURE...THEN WILL WARM TO AROUND 5 DEGREES BELOW NORMAL
ON SATURDAY AND SUNDAY...FINALLY REACHING NEAR NORMAL BY MONDAY.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...GRADUALLY EXPANDING -RA/DZ AND LOWERING CIGS
ARE EXPECTED THROUGH THE MORNING HOURS...WITH TEMPO IFR CIGS
EXPECTED BEGINNING AS EARLY AS 15Z (UPSTATE SC TERMINALS)...OR AS
LATE AS 16Z (NC TERMINALS)...WITH A TEMPO FROM 15-17Z APPEARING
REASONABLE AT KCLT. OTHERWISE...VISBY IS CERTAINLY THE LOWEST
CONFIDENCE COMPONENT OF THE FORECAST. GUIDANCE WAS MUCH TOO
AGGRESSIVE IN LOWERING VISBY THIS MORNING... OWING TO THE FACT THAT
IT WAS DEPICTING MUCH MORE WIDESPREAD AND MORE SIGNIFICANT PRECIP
THAN WHAT ACTUALLY OCCURRED. IN FACT...VERY DRY LOW LEVEL AIR HAS
ADVECTED INTO MUCH OF THE AREA...AND ITS GOING TO REQUIRE A AT LEAST
COUPLE OF HOURS OF LIGHT PRECIP TO MOISTEN THE LOW LEVELS AND REDUCE
VISBY. THEREFORE...VISBY RESTRICTIONS HAVE GENERALLY BEEN DELAYED
UNTIL AFTERNOON. OTHERWISE...ONCE CIGS LOWER TO IFR...THEY SHOULD
CONTINUE TO GRADUALLY LOWER TOWARD LIFR BY THIS EVENING AT MOST
TERMINALS... LIKELY REMAINING SO THROUGH THE END OF THE PERIOD.
WINDS AT 5-10 KTS WILL GRADUALLY WEAKEN THROUGH THE DAY...THEN
BECOME LIGHT SOUTHERLY OVERNIGHT. LLWS IS THEN EXPECTED LATE
TONIGHT...AS A LOW LEVEL JET DEVELOPS ACROSS THE SOUTHEAST.

OUTLOOK...A COLD FRONT WILL MOVE SLOWLY THROUGH THE REGION WED
THROUGH THURSDAY...BRINGING CHANCES FOR HEAVIER RAINFALL AND LOW
CIGS/VSBYS TO THE AREA. VFR CONDITIONS ARE EXPECTED TO RETURN
FOR FRIDAY AND SATURDAY.

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...JDL


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