Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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 030835
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
335 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 AN
APPROACHING COLD FRONT. THIS FRONT IS FORECAST TO PASS THROUGH THE
AREA ON THURSDAY...DRYING US OUT THURSDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
STILL NOT MUCH ACTION INDICATED ON REGIONAL RADAR IMAGERY EARLY THIS
MORNING...BUT -RA AND DZ SHOULD GRADUALLY EXPAND THROUGH THE MORNING
ISENTROPIC LIFT AND MOISTURE DEEPENS SOMEWHAT. MOST AREAS WILL THEN
SEE OCCL -RA/DZ PERSIST THROUGH MUCH OF THE DAY. IN TERMS OF THE
FREEZING RAIN ADVISORY...DRIER AIR...SUBSTANTIALLY DRIER THAN
INDICATED IN EARLIER MODEL RUNS...CONTINUES TO ADVECT INTO THE AREA
FROM THE NORTHEAST. THEREFORE EXPECT WET BULB TEMPS TO BE AT OR
BELOW FREEZING ACROSS NORTHERN BLUE RIDGE AREAS BY AROUND SUNRISE.
OF COURSE...THIS SAYS NOTHING OF THE ACTUAL OCCURRENCE OF
PRECIP/QPF...AND THE LATER PRECIP GETS STARTED...THE LESS LIKELY IT
WILL BE TO FALL AS FREEZING RAIN/DZ. NEVERTHELESS...SEE NO REASON TO
MAKE ANY CHANGES AT THIS TIME...BUT IF INDEED FREEZING RAIN DOES
OCCUR...IT WILL BE A VERY LOW IMPACT EVENT.

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 /09Z TUESDAY THROUGH SATURDAY/...
AT KCLT AND ELSEWHERE...FINALLY SEEING SOME EXPANSION OF MVFR CIGS
ACROSS PORTIONS OF UPSTATE SC AND FAR WESTERN NC...BUT THE ONSET OF
SAID LOWER CIGS HAS BEEN DELAYED AT KHKY/KCLT UNTIL 08-10Z.
OTHERWISE...AREAS OF PATCHY -RA AND DZ WILL GRADUALLY EXPAND ACROSS
THE AREA THROUGH THE MORNING...WITH VISBY RESTRICTIONS BECOMING MORE
LIKELY BY DAYBREAK AT THE SC TERMINALS AND KAVL. CIGS ARE ALSO
EXPECTED TO  LOWER TO IFR...BUT NOT UNTIL AFTER SUNRISE AT MOST
TERMINALS... ALTHOUGH A TEMPO FOR BKN008 HAS BEEN INCLUDED AT KAND
AFTER 11Z. ONCE DETERIORATION TO IFR OCCURS...CIGS WILL REMAIN LOW
THROUGH THE DAY AND INTO TUE EVENING...ACCOMPANIED BY OCCL -RA/DZ
AND REDUCED VISBY...AS COLD AIR DAMMING EVENT BECOMES ESTABLISHED.
IN FACT...LIFR CONDITIONS WILL LIKELY BECOME ESTABLISHED AT SOME
POINT...ALTHOUGH THE EXACT TIMING OF THAT IS DIFFICULT TO PIN DOWN
ATTM. OTHERWISE...NE WINDS WILL PERSIST THROUGH THE PERIOD. WITH
FLOW TURNING RAPIDLY TOWARD THE SW ABOVE THE COOL WEDGE...THERE WILL
BE ENHANCED LL WIND SHEAR...BUT NOT QUITE REACHING CRITERIA FOR A
TAF MENTION.

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...FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NCZ033-049-050-
     501-503-505.
SC...NONE.

&&

$$
SYNOPSIS...JAT
NEAR TERM...JDL
SHORT TERM...JAT
LONG TERM...JAT
AVIATION...JDL


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