Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 271138
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
738 AM EDT MON APR 27 2015

.SYNOPSIS...
A LARGE COOL AND DRY AIR MASS WILL DOMINATE THE WEATHER ACROSS THE
SOUTHERN APPALACHIAN REGION THROUGH TUESDAY. A WELL ORGANIZED LOW
PRESSURE SYSTEM WILL LIFT ACROSS THE DEEP SOUTH...TRACKING ALONG THE
ATLANTIC COAST DURING THE MID WEEK. ANOTHER CANADIAN AIR MASS WILL
SETTLE BACK OVER THE REGION DURING THE LATE WEEK AND WILL REMAIN
INTO THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 700 AM MONDAY...GRIDS IN GOOD SHAPE FOR THE MOST PART THIS
MORNING WITH ONLY SOME MINOR TWEAKS ESPECIALLY IN SKY GRIDS. ADDED
SOME LINGERING PATCHY FOG TO THE PIEDMONT...ESPECIALLY AROUND THE
CHARLOTTE METRO AREA...BUT FOG IS ALREADY SHOWING SIGNS OF
IMPROVEMENT SO WILL LEAVE THE SPS IN PLACE FOR NOW.

AS OF 500 AM MONDAY...CLOUDS ARE BEGINNING TO MOVE OUT OF THE AREA
BUT WE ARE STARTING TO SEE AN EXPANDING AREA OF FOG ACROSS THE SC/NC
PIEDMONTS AROUND CHARLOTTE. WIND SPEEDS ARE RUNNING A LITTLE LOWER
THAN FORECAST PREVENTING WHAT LITTLE MIXING WAS EXPECTED. FORECAST
GRIDS ARE CARRYING SOME FOG MENTION ALREADY BUT WILL HAVE TO KEEP A
CLOSE EYE ON OBS IN CASE DENSE FOG BECOMES AN ISSUE. OTHERWISE...
JUST SOME MINOR TWEAKS TO TEMP/DEWPOINT TRENDS.

AS OF 230 AM MONDAY...THE NEAR TERM IS OVERALL FAIRLY QUIET. LARGE
UPPER LOW SPINNING OFF NEW ENGLAND KEEPS US IN NORTHWEST FLOW IN THE
WAKE OF THE COLD FRONT THAT PUSHED THROUGH YESTERDAY. ANOTHER
SHORTWAVE SPINS AROUND THE WESTERN PERIPHERY OF THE LOW...PUSHING
THROUGH THE SOUTHERN APPALACHIANS TONIGHT. SURFACE HIGH PRESSURE
LOCKED ACROSS THE GREAT LAKES UNDER THE CONFLUENT FLOW TONIGHT WILL
CONTINUE TO RIDGE TOWARD THE SOUTHEAST...KEEPING THE SENSIBLE
WEATHER DRY THROUGH THE NEAR TERM. NEXT WEATHER-MAKER IS A CUTOFF
LOW OVER THE SOUTHERN PLAINS THAT WILL BRING A SURFACE LOW FROM THE
GULF INTO THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST...BUT WITH NO
IMPACTS UNTIL THE SHORT TERM PERIOD. THE FEW CLOUDS OUT THERE AT AFD
TIME WILL CONTINUE TO DISSIPATE THROUGH THE MORNING HOURS...THOUGH
BUFR SOUNDINGS DO INDICATE ENOUGH RH AT THE TOP OF THE MIXED LAYER
THAT WE COULD SEE SOME FAIR-WEATHER CUMULUS DEVELOPING THIS
AFTERNOON.

THE PRIMARY CONCERN THROUGH THE NEAR-TERM WILL BE TEMPERATURES
OVERNIGHT TONIGHT...WHICH ARE PROGGED TO BE 5 OR SO DEGREES BELOW
NORMAL FOR MOST OF THE UPSTATE/PIEDMONT/FOOTHILLS. THE PROBLEM MIGHT
BE IN THE MOUNTAINS WITH DEEP LAYER /ALBEIT WEAK/ CAA THROUGH THE
COLUMN. THIS COMBINED WITH THE DECREASING SURFACE PRESSURE GRADIENT
AS THE HIGH CONTINUES TO RIDGE IN...AND WINDS WILL DROP OFF TONIGHT.
BASED ON TEMPS...DEWPOINT DEPRESSIONS...AND WINDS...EXPECT TO SEE
SOME FROST DEVELOPING JUST BEFORE SUNRISE AT THE HIGHER ELEVATIONS
OF THE NORTH CAROLINA MOUNTAINS. HOWEVER...AREAL EXTENT OF CURRENTLY
FORECAST FROST COVERAGE IS NOT ENOUGH TO WARRANT AN ADVISORY AT THIS
TIME. OVERNIGHT TEMPS/DEWPOINTS/WINDS WILL HAVE TO BE CLOSELY
REEVALUATED THROUGH THE DAY WITH UPDATED GUIDANCE IN CASE AN
ADVISORY BECOMES WARRANTED.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
AS OF 230 AM MONDAY...SHORT RANGE MODELS AGREE THAT TUESDAY WILL SEE
DRY CONDITIONS UNDER S/W RIDGING. FORECAST SOUNDINGS INDICATE THAT
MOISTURE WILL INCREASE STEADILY FROM THE TOP-DOWN DURING THE
DAYLIGHT HOURS...DEEPEST ACROSS THE SW. A CONSENSUS OF THE
TEMPERATURE GUIDANCE SUPPORT HIGH TEMPERATURES RANGING FROM THE MID
60S WITHIN THE MTN VALLEYS TO THE UPPER 60S EAST...OR 5 TO 7 DEGREES
BELOW NORMAL.

ON WEDNESDAY...SHORT RANGE MODELS REMAIN IN GENERAL AGREEMENT...ALL
MAINSTREAM SOLUTIONS INDICATE THAT THE SFC LOW WILL LIFT NORTH
ACROSS THE FL PANHANDLE EARLY WEDNESDAY...REACHING THE CAROLINA
COAST BY WEDNESDAY EVENING. AT THE MID LEVELS...A DEEP TROF WILL
SLIDE EAST...REACHING THE SOUTHERN APPALACHIANS BY WEDNESDAY
AFTERNOON. A WIDE FIELD OF MODERATE Q-VECTOR CONVERGENCE IS FORECAST
TO SWEEP ACROSS THE CAROLINAS WEDNESDAY AFTERNOON. AT THE LOW
LEVELS...THE LOW CIRCULATION WILL RESULT IN EAST WINDS AT
H85...PROVIDING UPSLOPE FLOW DURING THE MORNING HOURS. THE
COMBINATION OF DEEP MOISTURE...DEEP SYNOPTIC SCALE FORCING...AND
LLVL UPSLOPE FLOW SHOULD RESULT IN RAPID INCREASE IN RAINFALL
COVERAGE ON WEDNESDAY. TEMPERATURES MAY BEGIN THE DAY AROUND
50...RISING TO AROUND 60 DURING THE AFTERNOON. THE EXPANDING
RAINFALL AND THICK CLOUD COVER SHOULD LIMIT DAYTIME TEMPERATURES TO
NEARLY 20 DEGREES BELOW NORMAL.

THURSDAY...THE ECMWF INDICATE THAT A BROAD MID LEVEL TROF WILL SWING
ACROSS THE REGION...THE GFS INDICATES THAT THE CORE OF A 540 CLOSED
LOW WILL TRACK OVER THE NC MTNS BY 0Z FRI. I WILL USE A BLEND OF THE
TWO SOLUTIONS...WHICH WILL YIELD MORE CLOUDS AND PRECIP THAN THE
INHERITED FORECAST. I WILL INCREASE SKY TO MOSTLY CLOUDY THROUGH
MID DAY...THEN INDICATE CLOUD COVER ERODING WITHIN THE DOWNSLOPE
AREAS THURSDAY AFTERNOON. IN ADDITION...I WILL KEEP CHC POPS THROUGH
THE DAYLIGHT HOURS. LIGHT RAIN TO RAIN SHOWERS SHOULD OCCUR BOTH
WEDNESDAY AND THURSDAY...MODEL INSTABILITY IS VERY WEAK.
TEMPERATURES ARE FORECAST TO WARM ABOVE WEDNESDAY/S VALUES BY 5 TO 8
DEGREES. QPF ON THURSDAY SHOULD REMAIN LESS THAN A QUARTER OF AN
INCH.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
AS OF 300 AM MONDAY...THROUGH THE EXTENDED...THE COASTAL SFC LOW
WILL LIKELY CONTINUE TO TRACK NORTHEAST AND INTENSIFY. DRY CANADIAN
HIGH PRESSURE WILL SWEEP ACROSS THE SOUTHERN APPALACHIAN REGION
DURING THE LATE WEEK AND REMAIN INTO THE WEEKEND. AT THE MID
LEVELS...A BROAD TROF WILL SLOWLY GIVE WAY TO RISING HEIGHTS FROM
THE WEST. FRIDAY-SUNDAY SHOULD SEE MODERATING
TEMPERATURES...BEGINNING BELOW NORMAL AND ENDING WITH TEMPERATURES
VERY CLOSE TO NORMALS. OVERALL...CONDITIONS WILL REMAIN DRY WITH
PARTLY CLOUDY SKY COVER.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
AT KCLT...SOME PATCHY MVFR VSBY AROUND THE KCLT AREA BUT ANY
IMPACTS TO KCLT ITSELF SHOULD BE LIMITED TO ONLY THE FIRST HOUR OR
SO OF THE TAF. OTHERWISE...EXPECT VFR CONDITIONS THROUGH THE PERIOD.
ONCE THE LOW VFR CLOUDS CLEAR SOUTH OF THE AREA SHOULD SEE MAINLY
HIGH CLOUDS PASSING THROUGH BUT CANNOT RULE OUT SOME BRIEF FEW-SCT 5-
6KFT CU THIS AFTERNOON. NW WINDS GENERALLY THROUGH THE PERIOD BUT
PICKING UP TO BETWEEN 5-10KT THIS AFTERNOON...WITH POTENTIAL FOR A
BRIEF VERY LOW-END GUSTS.

ELSEWHERE...VERY SIMILAR TREND TO CLT. ONLY PATCHY MVFR VSBYS THIS
MORNING BUT FOR NOT NOT AFFECTING THE TAFS. GENERALLY NNW TO BRIEFLY
NNE WINDS EVERYWHERE BETWEEN 5-10KT THIS AFTERNOON...BUT WILL
PROBABLY SEE SLIGHTLY STRONGER WINDS AT KAVL...10KT OR JUST ABOVE
WITH GUSTING POTENTIAL TO 20KT OR SO.  OTHERWISE JUST HIGH CLOUDS
THROUGH THE PERIOD.

OUTLOOK...DRY HIGH PRESSURE WILL CONTINUE THROUGH TUESDAY. ANOTHER
LOW PRESSURE SYSTEM WILL TRACK ACROSS THE DEEP SOUTH WEDNESDAY AND
THURSDAY...WITH CEILING AND VSBY RESTRICTIONS POSSIBLE.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       HIGH  93%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH  93%     HIGH 100%     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...NED
NEAR TERM...TDP
SHORT TERM...NED
LONG TERM...NED
AVIATION...TDP


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