Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
636 AM EDT THU JUL 24 2014

.SYNOPSIS...
A COLD FRONT WILL APPROACH FROM THE NORTHWEST THIS MORNING AND 
SHOULD MOVE ACROSS THE CAROLINAS AND NORTH GEORGIA THIS AFTERNOON 
AND EVENING. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR FRIDAY 
AND THE WEEKEND. ANOTHER FRONT IS EXPECTED TO PASS ON MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 520 AM...LATEST WATER VAPOR IMAGES INDICATED THAT THE MID 
LEVEL TROF WAS LOCATED GENERALLY OVER THE TN/NC LINE...WITH A S/W 
OVER THE PIEDMONT. KGSP AND TCLT RADAR INDICATED SHOWERS AND 
THUNDERSTORMS ASSOCIATED WITH EACH FEATURE. I WILL UPDATE THE 
FORECAST TO INCREASE POPS ALONG AND EAST OF THE OBSERVED CONVECTION. 
OTHERWISE...THE CURRENT FORECAST APPEARS IN GREAT SHAPE.

AS OF 330 AM...RECENT REGIONAL RADAR INDICATED THAT THE CONVECTION 
ACROSS EASTERN TN HAS DECREASED TO ISO SHOWERS...WITH A SECONDARY 
PATCH OF SHOWERS ACROSS THE SOUTHERN I-77 CORRIDOR. W/V SHOWED THE 
MID LEVEL TROF AXIS WAS LOCATED ACROSS EASTERN KY/TN...SWEEPING 
EAST. AT 330 AM...W/V AND RAP INDICATED THAT SEVERAL S/W EXISTED EAST 
OF THE TROF AXIS...WITH STRONGER S/W ACROSS THE WESTERN OHIO RIVER 
VALLEY. I ANTICIPATE THAT WIDELY SCT TO SCT SHRA WILL DRIFT OR 
DEVELOP ACROSS NC MTNS EARLY THIS MORNING. BY MID DAY...THE MID 
LEVEL TROF IS EXPECTED TO RIPPLE OVER THE SOUTHERN APPALACHIAN 
REGION. BY 17Z...FORECAST SOUNDINGS INDICATE THAT CAPES WILL RANGE 
BETWEEN 1000-1500 J/KG ACROSS THE REGION. AS WEAK MID LEVEL FORCING 
REACHES THE MTNS AND FOOTHILLS EARLY THIS AFTERNOON...CONVECTION 
SHOULD DEVELOP ACROSS THE EAST FACING SLOPES AND FOOTHILLS. FORECAST 
SOUNDINGS INDICATE THAT THE STEERING FLOW WILL PUSH CELLS NW TO SE 
ACROSS THE WESTERN CAROLINAS AND NE GEORGIA. SHEAR MAY REMAIN WEAK 
THROUGH THIS AFTERNOON...BUT POSSIBLY ENOUGH TO ORGANIZE CONVECTION 
INTO A BAND. ONCE DEVELOPED...THE BAND SHOULD SLIDE 
QUICKLY EAST...REACHING THE CLT AREA BY LATE AFTERNOON. THESE STORMS 
MAY RESULT IN STRONG TO SEVERE TSRA WIND GUSTS ACROSS PORTIONS OF 
THE OF THE FORECAST AREA. IN ADDITION...DCAPE ACROSS THE EASTERN 
PIEDMONT MAY RANGE FROM 500-1000 J/KG. WE WILL HIGHLIGHT IN THE HWO 
THE POTENTIAL FOR DAMAGING WIND GUSTS ASSOCIATED WITH THE FORECAST 
THUNDERSTORM BAND. HIGH TEMPERATURES MAY RANGE FROM 80 WITHIN THE 
MTN VALLEYS NEAR 90 EAST OF I-85. 

THIS EVENING...CONVECTION WILL PROPAGATE EAST...EXITING THE CWA 
EARLY THIS EVENING. OVERNIGHT...CONDITIONS WILL DRY WITH CLOUD COVER 
DECREASING FROM WEST TO EAST. LOW TEMPERATURES MAY RANGE 2-3 DEGREES 
COOLER THAN THIS MORNING.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
AS OF 300 AM THURSDAY...THE SHORT RANGE IS SHAPING UP TO BE 
RELATIVELY QUIET. THE FRONT SHOULD BE DRIVEN FAR ENOUGH S TO NOT 
AFFECT THE REGION ON FRIDAY. THE UPPER TROF OVER THE EAST SHOULD 
PULL OUT OR FILL A BIT ON FRIDAY INTO SATURDAY WITH WEAK SURFACE 
HIGH PRESSURE MOVING OVER THE REGION. THE MODELS CONTINUE TO 
ALTERNATELY DEPICT ISOLATED/WIDELY SCATTERED SHOWER DEVELOPMENT 
DURING HEATING ON FRIDAY AND SATURDAY...BUT THE SITUATION DOES NOT 
APPEAR TO HAVE A WHOLE LOT GOING FOR IT AS MOISTURE SHOULD BE MUCH 
LESS THAN THE LAST WEEK. A FEW SHORT WAVES WILL MOVE ACROSS THE 
REGION BUT THE MODELS DO NOT RESPOND TO ANY GREAT DEGREE. AT THIS 
POINT...WOULD PREFER TO REMAIN OPTIMISTIC FOR THE FIRST PART OF THE 
WEEKEND AND HAVE KEPT THE FCST DRY. ANY BRIEF DROP IN TEMPS ON 
FRIDAY WILL BE WIPED OUT FOR SATURDAY AS THE AIR MASS MODIFIES BACK 
TO NORMAL. TOWARD THE END OF THE PERIOD...THERE IS SOME POTENTIAL 
FOR AN MCS OR REMNANTS TO APPROACH FROM THE W OR NW...SO A SMALL POP 
WAS INTRODUCED ON THE TN BORDER.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 330 AM THURSDAY...THE MEDIUM RANGE HAS PERHAPS A BIT MORE 
UNCERTAINTY THROWN IN FOR SUNDAY AND MONDAY. THE RETURN MOISTURE 
DOES NOT APPEAR TO BE AS GREAT ON SUNDAY AND ANY UPPER SUPPORT FOR 
CONVECTION SHOULD MOVE PAST TO THE NORTH...TO THE POINT WHERE THE 
GFS/ECMWF BOTH FAIL TO DEVELOP MUCH IN THE WAY OF PRECIP. AT THE 
SAME TIME...THE MODELS CONTINUE TO SUGGEST SOME SORT OF MCS 
ACTIVITY...BUT KEEP IT MOVING ACROSS THE OH VALLEY/CENTRAL 
APPALACHIANS. THERE IS THE POTENTIAL FOR A BOUNDARY TO MOVE DOWN 
FROM THAT ACTIVITY WHICH COULD TRIGGER SOME STORMS. WILL NOT MAKE 
ANY CHANGES TO THE PRECIP PROBS FOR SUNDAY...BUT KEEP IN MIND THE 
TREND IS FOR LESS ACTIVITY ON THAT DAY. THE MODELS CONTINUE TO 
DEEPEN THE UPPER TROF OVER THE EAST AGAIN ON MONDAY WITH STRONGER 
WAVES DRIVING ANOTHER SURFACE COLD FRONT SE ACROSS THE REGION...MOST 
LIKELY ON MONDAY. IN SPITE OF THIS BOUNDARY BEING MORE SIGNIFICANT 
IN TERMS OF AIR MASS CHANGE...THE MODEL RESPONSE IS UNDERWHELMING IN 
TERMS OF PRECIP. AGAIN...WILL NOT MAKE ANY CHANGES...BUT A DOWNWARD 
TREND MIGHT BE STARTED LATER TODAY. STILL LOOKS BELOW NORMAL FOR THE 
MIDDLE OF NEXT WEEK AS A SURFACE HIGH OF CONTINENTAL ORIGIN DROPS 
DOWN FROM CANADA/NRN PLAINS. HAVE NUDGED TEMPS/DEWPTS DOWN A BIT 
MORE FOR TUESDAY NIGHT INTO WEDNESDAY.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
AT KCLT...THE PRIMARY FORECAST CHALLENGE WILL BE THE TIMING OF 
AFTERNOON TSRA. THE 4KM WRF AND 6Z NAM12 INDICATES THAT CONVECTION 
WILL DEVELOP ACROSS THE NC FOOTHILLS BETWEEN 18Z-19Z...FORMING A 
BAND. STEERING FLOW AND COLD POOL GENERATION SHOULD RESULT IN THE 
BAND TO MOVE BRISKLY EAST DURING THE AFTERNOON...LIKELY PASSING 
ACROSS THE CLT METRO AREA BETWEEN 20Z TO 22Z. I WILL HIGHLIGHT THE 
TSRA POTENTIAL WITH A TEMPO GROUP FROM 21Z TO 24Z. ALTHOUGH FROPA 
SHOULD OCCUR BETWEEN 18Z-0Z...LIGHT NORTH WINDS ARE NOT FORECAST TO 
DEVELOP UNTIL THIS EVENING. THE COMBINATION OF LIGHT NORTH 
WINDS...LINGERING MID LEVEL CLOUD COVER...AND 2-3 DEGREE DEWPOINT 
DEPRESSIONS SHOULD FAVOR VFR CONDITIONS TONIGHT.

ELSEWHERE...ALL TERMINALS WILL LIKELY SEE CONVECTION EITHER OVER THE 
TERMINAL OR VICINITY THROUGH 0Z. I WILL HIGHLIGHT THE CONVECTIVE 
PERIOD WITH VCTS OR TEMPO GROUPS...GENERALLY BETWEEN 19Z-22Z. AHEAD 
OF THE COLD FRONT FLOW WILL REMAIN FROM THE SOUTHWEST BETWEEN 
5-10KTS. WINDS WILL VEER FROM THE NORTH THIS EVENING. KAVL COULD SEE 
NNW WINDS DEVELOP THIS MORNING...REMAINING THROUGH THE REST OF THE 
12Z PACKAGE. NAM CONDENSATION PRESSURE DEFICITS AND MOS INDICATES 
THAT KAVL COULD SEE IFR CEILINGS DURING THE PRE DAWN HOURS FRI.
  
OUTLOOK...FRI AND SAT SHOULD BE QUIET AND VFR...EXCEPT FOR THE MTN 
VALLEYS WHERE EARLY MORNING FOG MAY OCCUR. THUNDERSTORMS WILL RETURN 
TO THE FORECAST FOR SUNDAY AFTERNOON THROUGH MON AS ANOTHER COLD 
FRONT APPROACHES AND THEN MOVES THROUGH THE AREA ON MON.

CONFIDENCE TABLE...

            10-16Z        16-22Z        22-04Z        04-10Z 
KCLT       HIGH  98%     HIGH 100%     HIGH 100%     HIGH 100%     
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%     
KAVL       MED   65%     HIGH 100%     HIGH  92%     MED   66%     
KHKY       HIGH  97%     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...PM
NEAR TERM...NED
SHORT TERM...PM
LONG TERM...PM
AVIATION...NED




National Weather Service Glossary of Abbreviations