Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 291903
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
303 PM EDT SUN MAR 29 2015

.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFF THE SOUTHEAST COAST TONIGHT. A LOW
PRESSURE CLIPPER SYSTEM AND ASSOCIATED COLD FRONT WILL THEN PASS
OVER THE AREA EARLY MONDAY MORNING. HIGH PRESSURE WILL RETURN FOR
MIDWEEK...WITH ANOTHER COLD FRONT APPROACHING THE REGION BY THE END
OF THE WORK WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 230 PM...DRY HIGH PRESSURE CURRENTLY OVER THE CAROLINA COASTAL
PLAIN WILL MOVE OFFSHORE THIS EVENING AS SFC/UPPER TROUGH BEGINS TO
DIG INTO THE OHIO VALLEY. A FAST MOVING BUT NOT ESPECIALLY
STRONG COLD FRONT WILL SWING THROUGH THE AREA MONDAY MORNING IN
ASSOCIATION WITH THE TROUGH.

WARM ADVECTION WILL GET UNDERWAY ALOFT BY THIS EVENING AHEAD OF THE
FRONT...REINTRODUCING CLOUD COVER AND ALSO CREATING A WARM NOSE OF
SORTS THAT WILL CAP THE COOL AND DRY AIRMASS ALREADY IN PLACE. UPPER
DYNAMIC FORCING COMES INTO PLAY AS THE TROUGH ARRIVES
09-12Z...CONCURRENT WITH MODEST FRONTOGENETIC FORCING IN THE LLVLS
AND WITH DEEP SATURATION. GUIDANCE IS VIRTUALLY UNANIMOUS IN
BRINGING A BAND OF QPF ACRS THE AREA AS A RESULT. TEMPS TONIGHT
AGAIN WILL BE BELOW NORMAL...BUT WARM ENOUGH OVER MOST OF THE
PIEDMONT AND MTN VALLEYS TO CONFIDENTLY FORECAST AN ALL RAIN EVENT.
HOWEVER...THE PRESENCE OF THE WARM NOSE AND THE INCUMBENT DRY AIR AT
THE SFC POSE A SMALL CHANCE THAT WINTRY PRECIP COULD OCCUR AT THE
ONSET OF PRECIP. WET BULB TEMPS ARE EXPECTED TO BE BELOW 0C
THROUGHOUT THE HIGHER ELEVATIONS OF THE MTNS UNTIL SUFFICIENT
MOISTURE RETURNS JUST PRIOR TO FROPA. THE STRENGTH OF THE WARM NOSE
WOULD SUGGEST NO NUCLEATION...AND FZRA RESULTING AT THE SFC IF THE
WET BULBS WERE TO COOL ENOUGH. THE MORE LIKELY SCENARIO IS THAT
PRECIP WILL NOT GET UNDERWAY UNTIL AFTER THE WET BULBS WARM ABOVE
0C. A FEW HIGH ELEVATION LOCATIONS DO GET A SNOW OR RA/SN MENTION
AROUND DAYBREAK...WHEN THE FRONT IS EXPECTED TO HAVE ERODED THE WARM
NOSE AND AIR TEMPS REMAIN JUST ABOVE FREEZING.

PEAK FORCING APPEARS TO OCCUR OVER THE PIEDMONT AROUND 12-14Z...AND
POPS SHOULD QUICKLY TRAIL OFF AS THE FRONT DEPARTS THRU THE REST OF
THE MRNG. WEAK UPSLOPE FORCING WILL PROLONG THE PRECIP CHANCES ALONG
THE TENN BORDER...BUT BY MID AFTN ALL PRECIP SHOULD HAVE COME TO AN
END. WINDS FLIPPING TO NWLY...AND THUS DOWNSLOPE...AS WELL AS
CLEARING SKIES SHOULD ALLOW TEMPS TO RISE TO NEAR NORMAL FOR AFTN
MAXES.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 230 PM EDT SUNDAY...SFC HIGH PRESSURE WILL BUILD BRIEFLY OVER
THE SRN APPALACHIANS MON NIGHT BEFORE MOVING OFF THE SE COAST
THROUGH TUE. RADIATIONAL COOLING CONDITIONS WILL LIKELY BECOME
FAVORABLE ENOUGH FOR NEAR FREEZING TEMPERATURES IN PARTS OF THE
CENTRAL AND SRN MOUNTAINS...WHERE THE FROST/FREEZE SEASON IS NOW
ACTIVE. AN HWO MENTION OF POTENTIAL FREEZING TEMPERATURES WILL BE
ADDED FOR TUESDAY MORNING IN THIS AREA. OTHERWISE...DEEP LAYER NW
FLOW WILL SET UP OVER THE REGION ON TUESDAY. MAX TEMPS WILL REBOUND
TO ABOUT A CATEGORY ABOVE CLIMO TUE AFTN.

A BACKDOOR COLD FRONT WILL PUSH SWD THROUGH THE VIRGINIAS TUESDAY
NIGHT AND ENTER THE NRN TIER OF THE FORECAST AREA ON WED. WEAK
UPGLIDE MOISTURE MAY SET UP FROM THE SW ON WED...BUT WILL PROBABLY
NOT PROVIDE ENOUGH QPF TO ALLOW ANY SHALLOW COLD AIR DAMMING TO GET
ESTABLISHED. ANY INSTABILITY WED AFTN SHOULD BE LIMITED TO THE SW
HALF IN THE BETTER DEWPOINT AIR...BUT NO THUNDER WILL BE FEATURED AT
THIS POINT. TEMPS WILL LIKELY RECOVER ANOTHER DEGREE ON TWO OVER TUE
VALUES...BUT THE NRN TIER COULD BE COOLER IF ANY CAD FORMS.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AT 230 PM EDT SUNDAY...ON WEDNESDAY EVENING A LOW AMPLITUDE UPPER
RIDGE WILL BE OVER THE GREAT LAKES...WITH TROUGHS OVER THE WESTERN
ATLANTIC AND WESTERN USA. NEARLY ZONAL FLOW WILL EXIST OVER THE
SOUTHERN TIER OF STATES...WITH A SHORTWAVE CROSSING THE SOUTHERN MS
RIVER VALLEY. THE UPPER RIDGE MOVES TO THE EAST COAST LATE
THURSDAY...WHILE THE SOUTHERN STREAM SHORTWAVE CROSSES THE SOUTHERN
APPALACHIANS. ON FRIDAY THE TROUGH UPSTREAM MOVES TO THE CENTER OF
THE NATION...BUT UPPER FLOW REMAINS ZONAL ACROSS THE SOUTHERN TIER
OF STATES. THE NORTHERN STREAM TROUGH AMPLIFIES ALONG THE EAST COAST
ON SATURDAY...THEN MOVES OFF THE COAST ON SUNDAY WHILE A LOW
AMPLITUDE RIDGE CROSSES THE PLAINS.

AT THE SURFACE...ON THURSDAY HIGH PRESSURE WILL BE OFF THE EAST
COAST...WHILE A COLD FRONT MOVES ACROSS THE MS RIVER VALLEY. ROBUST
GULF INFLOW WILL SPREAD MOISTURE FROM THE GULF STATES TO THE OH
RIVER VALLEY...REACHING AS FAR EAST AS THE SOUTHERN APPALACHIANS. ON
FRIDAY...THE PROGRESSION OF THE NORTHERN STREAM TROUGH WILL LEAD TO
THE SURFACE FRONT BECOMING MORE NE TO SW ORIENTED...AND TO LESS OF A
PRESSURE GRADIENT OVER THE GULF. THIS MAY REDUCE GULF INFLOW
SOMEWHAT...BUT THE PROGRESSION OF THE SURFACE RIDGE OFF THE EAST
COAST WILL ALLOW MORE MOISTURE TO SPREAD INTO GA AND THE CAROLINAS.
THE RESULT IS THAT PRECIPITATION CHANCES ARE EXPECTED TO INCREASE
AHEAD OF THE FRONT. THE COLD FRONT WILL CROSS OUR AREA EARLY
SATURDAY...FOLLOWED BY SOME BRIEF NW FLOW SHOWERS IN THE NC
MOUNTAINS WHERE THICKNESS VALUES SUPPORT AN ALL RAIN EVENT. DRY HIGH
PRESSURE SPREAD OVER THE AREA FROM THE WEST ON SUNDAY. TEMPERATURES
WILL RUN ABOVE NORMAL AHEAD OF THE FRONT...AND SLIGHTLY BELOW NORMAL
IN ITS WAKE.

&&

.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
AT KCLT...VFR THRU EARLY MONDAY MRNG. WITH HIGH PRESSURE AND A LEE
TROUGH BOTH HAVING INFLUENCE...WINDS EARLY THIS AFTN WILL BE
DIFFICULT TO PIN DOWN. THEY ARE EXPECTED TO PREVAIL SWLY LATER THIS
AFTN AND REMAIN THERE THRU TONIGHT. FAST MOVING UPPER DISTURBANCE
AND COLD FRONT WILL SWEEP THRU THE AREA MON MRNG. PRECIP IS MOST
LIKELY IN THE COUPLE HRS AFTER DAYBREAK BUT MAY LINGER INTO MIDDAY.
BEST MOISTURE REMAINS ELEVATED...BUT LLVL CONVERGENCE NEAR THE FROPA
IS LIKELY TO PRODUCE AN MVFR CIG...NOTWITHSTANDING ANY RESTRICTIONS
DURING SHRA. WINDS MAY GO NWLY BY 18Z BUT MORE LIKELY AFTER THAT
TIME.

ELSEWHERE...LARGELY AS AT KCLT THOUGH WITH GENERALLY MORE CERTAINTY
AS FAR AS SWLY WINDS THIS AFTN. MIDLEVEL CIGS WILL OVERSPREAD THE
AREA THIS EVENING FOLLOWED BY A FAIRLY SHORT LIVED PERIOD OF SHRA
INVOF THE FRONT. MVFR CIGS ARE EXPECTED TO BE THE ONLY RESTRICTIONS
WITH BREEZY CONDITIONS AND DRY AIR AHEAD OF THE FRONT MOST LIKELY
ALLOWING VSBY TO REMAIN HIGH. WINDS FLIP TO NW AT KAVL AROUND
DAYBREAK...AND A LITTLE LATER AT KHKY...BUT OTHERWISE SHOULD REMAIN
IN THE SW QUADRANT ELSEWHERE THRU 18Z.

OUTLOOK...HIGH PRESSURE WILL REGAIN CONTROL LATE MONDAY IN THE WAKE
OF THE FRONT. A WEAK LOW PRESSURE SYSTEM PASSING TO THE NORTH OF THE
REGION MAY BRING SOME LIGHT PRECIP EARLY WED...PERHAPS WITH A FEW
RESTRICTIONS OVER THE MTNS. AN APPROACHING WARM FRONT AND RESULTANT
MOISTURE RETURN WILL BRING BETTER CHANCES FOR RESTRICTIONS ACROSS
THE AREA LATER IN THE WEEK.

CONFIDENCE TABLE...

            19-01Z        01-07Z        07-13Z        13-18Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     MED   74%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAVL       HIGH 100%     HIGH 100%     MED   75%     HIGH  80%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH  86%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     MED   66%
KAND       HIGH 100%     HIGH 100%     HIGH  98%     HIGH  88%

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

&&

.FIRE WEATHER...
A DRY POLAR AIRMASS WILL REMAIN IN PLACE OVER THE AREA THIS
AFTERMOON AHEAD OF THE RETURN OF SOUTHERLY FLOW OVERNIGHT. RH VALUES
HAVE ALREADY DIPPED INTO THE TEENS OVER MUCH OF THE AREA. WINDS WILL
BE RATHER LIGHT BUT WITH OCCASIONAL LOW GUSTS. ENHANCED FIRE DANGER
EXISTS HOWEVER DUE TO DRY FUELS. IN COORDINATION WITH GA LAND
MANAGERS...A FIRE DANGER STATEMENT REMAINS IN EFFECT FOR NORTHEAST
GA THRU 7 PM.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...FIRE DANGER STATEMENT UNTIL 7 PM EDT THIS EVENING FOR GAZ010-
     017-018-026-028-029.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...JPT
NEAR TERM...WIMBERLEY
SHORT TERM...HG
LONG TERM...JAT
AVIATION...WIMBERLEY
FIRE WEATHER...WIMBERLEY


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