Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 031757
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1257 PM 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 1230 PM...PATCHES OF LIGHT RAIN AND DRIZZLE CONTINUE TO MOVE
EAST MAINLY ACROSS NE GEORGIA AND UPSTATE SC...AND THE SRN PART OF
THE CLT METRO AREA. THIS WAS IN GENERAL AGREEMENT WITH SOME OF THE
MESOSCALE MODELS. THE LIGHT PRECIP AND CLOUD COVER HAS KEPT TEMPS
COOL AND IN LINE WITH PREVIOUS THINKING. NO SIGNIFICANT CHANGES WILL
BE MADE.

REMAINDER OF 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 /18Z TUESDAY THROUGH SUNDAY/...
AT KCLT...A DIFFICULT SITUATION FOR THE AFTERNOON...AS SOME
VARIABILITY IS EXPECTED WITH WIND DIRECTION ALTERNATING BACK AND
FORTH BETWEEN ENE AND ESE. THE TREND SHOULD BE TOWARD THE WIND
VEERING AROUND TO SE LATER TODAY. THE CEILING AND VISIBILITY WILL
ALSO BE VARIABLE BETWEEN IFR/MVFR UNTIL EARLY THIS EVENING...WHEN
THE MODEL GUIDANCE SUGGESTS WE WILL LOCK IN THE LOW IFR FOR THE
OVERNIGHT PERIOD. A LIGHT WIND COMING AROUND TO SE WILL ONLY HELP
WITH SOME WEAK MOIST UPGLIDE. AT THE SAME TIME...THE FLOW AT 850 MB
WILL STRENGTHEN AS THE CORE OF A LOW LEVEL JET TRANSLATES E ACROSS
THE REGION...WHICH SHOULD RESULT IN SOME LOW LEVEL WIND SHEAR
DEVELOPING THE PRE-DAWN HOURS. SOME IMPROVEMENT IS EXPECTED IN THE
MID TO LATE MORNING WITH BOUNDARY LAYER WARMING AND A REDUCED THREAT
OF LIGHT PRECIP.

ELSEWHERE...SIMILAR TO KCLT. THE NE WIND MAY HOLD ON THE LONGEST AT
KHKY...BUT MOST PLACES OUTSIDE THE MTNS WILL KEEP A PREVAILING NE
WIND UNTIL SOME TIME IN THE EARLY EVENING...AROUND 02Z...WHEN WIND
WILL PROBABLY GO LIGHT AND VARIABLE. GUIDANCE IS QUITE PESSIMISTIC
WITH IFR/LIFR CONDITIONS INDICATED.

OUTLOOK...A COLD FRONT WILL MOVE SLOWLY THROUGH THE REGION WEDNESDAY
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...PM


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