038  
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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