Area Forecast Discussion
Issued by NWS Greer, SC

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FXUS62 KGSP 201038
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
638 AM EDT SAT SEP 20 2014

.SYNOPSIS...
A WEAK RIDGE OF HIGH PRESSURE WILL LINGER ATOP THE REGION THROUGH
TONIGHT. TEMPERATURES WILL MODERATE OVER THE WEEKEND BEFORE A COLD
FRONT CROSSES THE CAROLINAS SUNDAY NIGHT. COOL AND DRY HIGH PRESSURE
WILL SPREAD ACROSS THE REGION THROUGH MID WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
1030 UTC UPDATE...SKY COVER HAS BEEN UPDATED FROM THE LATEST
INFRARED SATELLITE IMAGERY. POPS HAVE BEEN FURTHER REDUCED ALONG THE
BLUE RIDGE PER RADAR TRENDS.

AT 230 AM EDT SATURDAY...AN UPPER TROUGH WILL AMPLIFY OVER THE UPPER
MS RIVER VALLEY TODAY...WHILE AN UPPER LOW PERSISTS OFF THE GA
COAST. THE UPPER TROUGH REACHES THE LOWER GREAT LAKES TONIGHT...
WHILE THE UPPER LOW WEAKENS AND MOVES UP THE CAROLINA COAST.

A RIDGE OF HIGH PRESSURE ASSOCIATED WITH A HIGH OFF THE COAST OF
NOVA SCOTIA WILL REMAIN BANKED UP AGAINST THE SOUTHERN APPALACHIANS.
THE MODELS SHOW DRIER AIR MOVING INTO OUR AREA FROM THE NE TODAY...
LIMITING THE CHANCE OF PRECIPIATION....DESPITE A LIGHT UPSLOPE FLOW
FROM THE SE. BY TONIGHT SURFACE WINDS BACK FROM NE TO N...
INTRODUCING A DOWNSLOPE COMPONENT...AS A SURFACE WAVE MOVES UP THE
CAROLINA COAST. TEMPERATURES WILL RUN NEAR NORMAL.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
AS OF 200 AM EDT SATURDAY...THE MAIN FEATURE OF THE SHORT RANGE
FORECAST WILL BE THE COLD FRONTAL PASSAGE SUNDAY NIGHT WHICH WILL
HAVE LITTLE FANFARE. WE START AT 12Z SUNDAY WITH PLENTY OF DRY AIR
AND LOW LEVEL WIND SHIFTING FROM NORTH TO NW IN RESPONSE TO A
COASTAL LOW DEPARTING THE NC OUTER BANKS MOVING NE. THERE WILL BE A
500MB TROUGH DROPPING SE FROM THE GREAT LAKES AT 12Z WITH ASSOCIATED
COLD FRONT CROSSING THE OHIO VALLEY. LOW LEVEL WIND WILL BACK FROM
NW AT 12Z TO WEST AT 18Z SUNDAY THEN WSW AT 00Z MONDAY AHEAD OF THE
COLD FRONT. ALL MODELS SHOW GOOD INSTABILITY AND CONVECTION AHEAD OF
THE FRONT AS IT CROSSES MID TN AND KY WITH 1700 CAPE ON THE GFS AT
18Z PASSING NASHVILLE. ALL INSTABILITY GOES AWAY QUICKLY WHEN THE
SUN GOES DOWN WHICH IS WHEN THE FRONT ARRIVES AT THE NC MTNS.
THERE IS NOW ENOUGH CAPE IN THE GFS MODEL TO TO HAVE THUNDER IN THE
NC COUNTIES BORDERING TN FROM 22Z SUNDAY TO 04Z MONDAY. ONLY SHOWERS
AFTER MIDNIGHT WHICH MAY LAST IN THE NC MTNS UNTIL NEAR DAYBREAK
MONDAY. THE FRONT CROSSES NE GA...CAROLINA FOOTHILLS AND MUCH OF THE
PIEDMONT WITHOUT ANY SHOWER ACTIVITY LATE SUNDAY NIGHT AND EARLY
MONDAY. MAX HEATING LATE MONDAY WILL RESULT IN SOME CONVECTION BUT
THE FRONT WILL BE TOWARD THE COAST AT THAT TIME. DRY AIR WILL MOVE
IN FROM NW OVER OUR AREA LATE MONDAY AND MONDAY NIGHT WITH CENTER OF
DRY AND COOLER HIGH PRESSURE OVER INDIANA AT 12Z TUESDAY.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 220 AM SATURDAY...THE MEDIUM RANGE FCST PICKS UP AT 12Z
TUESDAY WITH THE LONGWAVE UPPER TROF ALREADY LIFTED NE OF THE REGION
ON THE GFS AND THE LAST FRAME OF THE NAM SHOWING AXIS OF THE TROUGH
ALIGNED ACROSS THE EAST COAST STATES.  HEIGHTS WILL BE RISING FROM
THE WEST. THE CENTER OF THE HIGH WILL MOVE FROM INDIANA 12Z TUES TO
NEW ENGLAND 12Z WED. THIS HIGH WILL REMAIN NEAR NEW ENGLAND CREATING
A COOL WEDGE DOWN THE EASTERN SEABOARD FOR OUR REGION WED THROUGH
FRI. ANOTHER HIGH WILL CROSS CENTRAL CANADA IN MID WEEK AND MERGE
WITH THIS FIRST HIGH. 925MB WIND WILL BE FROM THE NE TUES AND BECOME
MORE EASTERLY WED AND THURS WITH A GOOD FETCH OFF THE ATLANTIC.
CLOUDINESS WILL SLOWLY INCREASE. THE UPPER PATTERN IN MID WEEK WILL
BE A BROAD RIDGE ACROSS THE CONTINENTAL 48 STATES. A TROUGH ENTERS
THE WESTERN STATES AT THE END OF THE WEEK. IN THE LATER HALF OF THE
WEEK THERE WILL BE DEEPER MOISTURE TO THE SOUTH OF OUR REGION AND
THE SEMI UPSLOPE WITH A GENERAL EAST WIND AT TIMES DEPENDING ON THE
ORIENTATION OF THE HIGH. WILL CONTINUE TO SLIGHT POPS FOR THE SOUTH
AND EAST ZONES LATE IN THE WEEK. TEMPS WILL BE A FEW DEGREES BELOW
NORMAL WITH PERHAPS THE COOLER OF THESE DAYS BEING ON THURSDAY.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
AT KCLT...VFR. DRIER AIR MOVING IN FROM THE NE WILL LIMIT SKY COVER
AND PRECIPITATION CHANCES. NE WINDS WILL PERSIST TODAY...BACKING TO
THE N TONIGHT AS LOW PRESSURE MOVES UP THE COAST. A GUIDANCE BLEND
DOES NOT FAVOR FOG THIS MORNING OR SUNDAY MORNING.

ELSEWHERE...THE ARRIVAL OF DRIER AIR FROM THE NE WILL LIMIT SKY
COVER AND POPS IN THE FOOTHILLS. MORNING RESTRICITIONS EVEN APPEAR
UNLIKELY AT KAVL AS CLOUD HEIGHTS HAVE RISEN. GUIDANCE DOES FAVOR
RESTRICTIONS AT KAVL SUNDAY MORNING. NE WINDS WILL PERSIST IN
THE FOOTHILLS TODAY...BACKING TO THE N TONIGHT AS LOW PRESSURE MOVES
UP THE COAST...WHILE KAVL WINDS WILL BACK FROM SE TO NW.

OUTLOOK...CONDITIONS SHOULD REMAIN GENERALLY VFR FOR THE LATTER PART
OF THE WEEKEND...BUT WITH MOUNTAIN VALLEY FOG NEAR KAVL IN THE EARLY
MORNING HOURS. A COLD FRONT WILL BRING A CHANCE FOR RESTRICTIONS
MAINLY OVER THE MTNS SUNDAY NIGHT AND MONDAY MORNING. HIGH PRESSURE
BUILDS BACK IN EARLY NEXT WEEK.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-10Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH  86%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   77%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH  93%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH  86%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH  87%     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...DEO
NEAR TERM...JAT
SHORT TERM...DEO
LONG TERM...DEO
AVIATION...JAT





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