Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 190240
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1040 PM EDT SAT OCT 18 2014

.SYNOPSIS...
CANADIAN HIGH PRESSURE WILL BUILD ACROSS THE REGION TONIGHT THROUGH
MONDAY. A WEAK COLD FRONT IS EXPECTED TO CROSS THE AREA
TUESDAY...BRINGING SMALL CHANCES OF RAIN TO SOME OF THE REGION. DRY
AND MOSTLY SUNNY WEATHER WILL PREVAIL THE REST OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 1035 PM...LATEST IR SATELLITE INDICATED CONSIDERABLE CLOUD
COVER ACROSS THE MTNS...RAGGED CLOUD COVER EAST. RADAR DATA FROM
KMRX AND KGSP INDICATED VERY FEW RETURNS ACROSS THE MTNS. I WILL
UPDATE THE FORECAST TO ADJUST SKY. THE REST OF THE FORECAST APPEARS
ON TRACK.

AS OF 735 PM...AN AMPLIFIED MID LEVEL DISTURBANCE WILL RIPPLE ACROSS
THE REGION THROUGH THE OVERNIGHT HOURS. THIS SYSTEM WILL GENERATE
STRONG LIFT...BUT WILL HAVE LIMITED MOISTURE. I WILL FORECAST SCHC
TO CHC POPS ACROSS THE NRN MTNS...WITH ISO COVERAGE SW ALONG THE TN
LINE. TEMPERATURES...TD...AND WIND APPEAR ON TRACK.

     PREVIOUS DISCUSSION...
A FINAL PIECE OF VORT ENERGY WILL ROTATE THRU THE DEEP CYCLONIC FLOW
TONIGHT...GIVING RISE TO THE POSSIBILITY OF NC MTN SHOWERS IN
ADDITION TO THE EXPANSION OF UPSLOPE AIDED CLOUDINESS. EAST OF THE
BLUE RIDGE...A MIXED...DRY AND MOSTLY CLEAR NIGHT IS EXPECTED WITH
SUNDAY MORNING MINIMUM TEMPERATURES 3 OR 4 DEG F BELOW CLIMO. SUNDAY
WILL FEATURE DEAMPLIFYING FLOW AND SFC RIDGING BUILDING IN FROM THE
NW. PIEDMONT MOSTLY CLEAR CONDITIONS WILL EXPAND INTO THE MTNS AS
UPSLOPE FLOW WANES. MAX TEMPERATURES ARE SLATED TO BE A FEW
CATEGORIES COOLER THAN TODAY.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 245 PM SATURDAY...AN UPPER TROF WILL EXIT THE REGION SUNDAY
NIGHT ALLOWING OVERALL FLOW TO FLATTEN AND SURFACE HIGH PRESSURE TO
BUILD ACROSS THE REGION SUNDAY NIGHT/MONDAY MORNING. ALTHOUGH THE
HIGH WILL NOT BE IN THE BEST POSITION (MOVING TO OUR EAST)...AND H85
FLOW INCREASES AFTER MIDNIGHT AHEAD OF THE NEXT TROF...THERE SHOULD
BE A SUBSIDENCE INVERSION DEVELOP ACROSS THE REGION. THEREFORE UNDER
CLEAR SKIES AND LIGHT WINDS...TEMPERATURES SHOULD PLUMMET ESPECIALLY
IN THE VALLEY LOCATIONS.

THE MODEL GUIDANCE CONTINUES TO COME IN COOLER AND COOLER. AS A
RESULT WE HAVE GONE WITH ONE OF OUR COLDER MODEL TEMPERATURE SETS OF
GUIDE...WHICH HAS TEMPERATURES TEMPERATURES IN THE 30S OVER THE NC
MOUNTAINS...AND UPPER 30S AND LOWER 40S ACROSS THE REMAINDER OF OUR
FORECAST AREA (FA). RUNNING OUR FROSTY TOOL...WE GET PATCHY FROST IN
MANY AREAS OF THE MOUNTAINS WHERE THE GROWING SEASON HAS ENDED...AND
NOT MUCH ELSEWHERE. AT LEAST AT THIS POINT I DO NOT HAVE FREEZING
TEMPERATURES AND HEADLINES ARE NOT WARRANTED. SHOULD TEMPERATURE
TRENDS CONTINUE...IT WOULD NOT BE SURPRISING TO HAVE SOME LIGHT FROST
ISSUES IN THE FOOTHILLS...AND OTHER COLDER LOCATIONS...SUNDAY NIGHT
AND MONDAY MORNING. MEANWHILE...GUIDE CONTINUES TO INSIST ON PATCH
FOG IN THE RIVER VALLEYS...AND WE WILL NOT FIGHT THE TREND.

THE NEXT UPPER TROF DEVELOPING IN THE WESTERN GREAT LAKES WILL MOVE
TO THE CENTRAL LAKES LATER MONDAY. CLOUDS SHOULD INCREASE LATE IN
THE DAY OVER OUR NC MOUNTAINS. ELSEWHERE IT SHOULD BE A NICE DAY
WITH A GOOD DEAL OF SUNSHINE AND TEMPERATURES A DEGREE OR TWO WARMER
THAN PREVIOUS DAYS READINGS.

OUR NEXT COLD FRONT...ASSOCIATED WITH THE UPPER TROF...WILL SWING
THROUGH THE REGION MONDAY NIGHT. THERE IS MEAGER MOISTURE...BUT WITH
A DECENT LOBE OF VORTICITY RIDING THROUGH OUR REGION...A FEW SHOWERS
WILL BE POSSIBLE IN THE UPSLOPE MOUNTAIN AREAS OF NC. ELSEWHERE...WE
WILL KEEP OTHER AREAS DRY...BUT WITH A SUBTLE INCREASE IN CLOUDS.

THE AFOREMENTIONED UPPER TROF WILL CLOSE OFF INTO AN UPPER LOW
PRESSURE SYSTEM OVER THE MID ATLANTIC TUESDAY. A PARADE OF VORTICITY
SPOKES WILL GRAZE THE NC MOUNTAINS AND LOCATIONS ROUGHLY ALONG AND
NORTH OF I40. WE WILL CONTINUE TO MENTION SOME LOW END POPS AT THOSE
PLACES TUESDAY. OUTSIDE THOSE AREAS SOME COLD AIR CU SHOULD DEVELOP
WITH THE OVERALL TROUGH NEARBY.

WE ARE CLOSE TO THE AVERAGE SUITE OF MODEL GUIDE BOTH MONDAY NIGHT
AND TUESDAY.

BENEATH A SHORT UPPER RIDGE...A DOME OF
CONTINENTAL HIGH PRESSURE MOVES FROM THE MID MISSISSIPPI VALLEY TO
THE CAROLINA COAST SUNDAY AND SUNDAY NIGHT. DRY AND SETTLED
CONDITIONS WILL PREVAIL. THICKNESSES INCH UP SLIGHTLY BY SUNDAY
NIGHT...AND LIGHT SOUTHERLY FLOW IS IMPLIED BY THE PATTERN...THOUGH
IT WILL BE TOO WEAK TO OFFSET THE EFFICIENT RADIATIVE COOLING. THUS
MINS WILL REMAIN SEVERAL DEGREES BELOW CLIMO. LIGHT FROST IS POSSIBLE
IN SOME OF THE MTN VALLEYS MON MRNG.

THE SOUTHERLY FLOW CONTINUES MONDAY THOUGH HEIGHTS BEGIN TO FALL
AGAIN AHEAD OF AN IMPENDING TROUGH AND SFC COLD FRONT...WHICH WILL
BRING LOW POPS TO THE MTNS BY MONDAY NIGHT. LLVL WAA IS NOT VERY
STRONG...BUT GIVEN THE MORE MODIFIED AIRMASS TEMPS WILL RISE A COUPLE
DEGREES HIGHER THAN SUNDAY. TEMPS MONDAY NIGHT WILL BE A LITTLE ABOVE
CLIMO IN THE PREFRONTAL ENVIRONMENT.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM EDT SATURDAY...LATEST GLOBAL MODELS AGREE THAT AN UPPER
CLOSED LOW JUST TO OUR NE TUE NIGHT WILL MOVE OFF THE MID ATLANTIC
COAST BY WED NIGHT...ALLOWING COOL CANADIAN HIGH PRESSURE CENTERED
OVER THE GREAT LAKES REGION TO RIDGE SOUTH INTO THE REGION THRU THIS
PERIOD. THE 00Z ECMWF SUGGESTS AN UPPER SHORTWAVE TROUGH WILL DROP
INTO THE REGION...PUSHING A RELATIVELY DRY COLD FRONT THROUGH THE
FORECAST AREA BY LATE SAT WHILE THE GFS KEEPS THE REGION UNDER WEAK
NW FLOW ALOFT THRU DAY 7. IN ANY RATE...OUR FORECAST AREA WILL BE
UNDER THE INFLUENCE OF DRY AND COOL CANADIAN HIGH PRESSURE
THROUGHOUT THE MEDIUM RANGE PERIOD. TEMPERATURES WILL START OUT
AROUND 5-10 DEGREES BELOW NORMAL ON WED...AND A GRADUAL WARMING
TREND IS EXPECTED THRU SAT.

&&

.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...AN AMPLIFIED MID LEVEL DISTURBANCE WILL
RIPPLE ACROSS THE REGION THROUGH THE OVERNIGHT HOURS. THIS SYSTEM
WILL GENERATE STRONG LIFT...BUT WILL HAVE LIMITED MOISTURE. I WILL
FORECAST SCHC TO CHC POPS ACROSS THE NRN MTNS...WITH ISO COVERAGE SW
ALONG THE TN LINE. KAVL MAY SEE A PERIOD OF MVFR CEILINGS LATE
TONIGHT...GUSTY WINDS THROUGH THE EVENING. ELSEWHERE...CONDITIONS
WILL REMAIN VFR. NORTHWEST WINDS SHOULD REMAIN THROUGH SUNDAY
MORNING...WITH SW WINDS POSSIBLE DURING THE AFTERNOON.

OUTLOOK...STRONG AND DRY HIGH PRES EXPECTED SUNDAY THRU THROUGH
TUESDAY. APART FROM PERHAPS SOME PATCHY LOW STRATUS AND FOG IN THE
MOUNTAIN VALLEYS EARLY EACH MORNING...VFR CONDITIONS SHOULD PERSIST.

CONFIDENCE TABLE...

            02-08Z        08-14Z        14-20Z        20-02Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  97%     HIGH  98%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     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...JOH
NEAR TERM...NED
SHORT TERM...TS
LONG TERM...JOH
AVIATION...NED





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