AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
1056 AM EDT FRI JUL 25 2014

.SYNOPSIS...A STALLED FRONT WILL REMAIN NEAR OR JUST SOUTH OF THE 
SOUTH CAROLINA BORDER THROUGH TONIGHT. A CLIMATOLOGICALLY MOIST AND 
UNSTABLE AIRMASS WILL PREVAIL OVER THE WEEKEND. AN UNSEASONABLY DEEP 
UPPER LEVEL TROUGH AND ATTENDANT COLD FRONT WILL APPROACH FROM THE 
NORTHWEST SUNDAY NIGHT...THEN CROSS THE REGION ON MONDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1045 AM FRIDAY...

OUTFLOW ASSOC/W CONVECTION THAT DEVELOPED ALONG THE COLD FRONT 
TRACKING SOUTHWARD THROUGH VA/NC YESTERDAY EVENING SERVED TO 1) 
STRENGTHEN THE FRONTAL ZONE AND 2) ACCELERATE THE FRONT SOUTHWARD. 
AS A RESULT OF THE AFOREMENTIONED ACCELERATION...THE FRONT WAS 
LOCATED WELL SOUTH OF CENTRAL NC THIS MORNING...EXTENDING ROUGHLY 
WEST-EAST FROM ATLANTA-COLUMBIA-MYRTLE BEACH AT 14Z. WV IMAGERY AND 
RAOB DATA INDICATED A DRY/SUBSIDENT AIRMASS OVER CENTRAL NC THIS 
MORNING...IN THE WAKE OF PRONOUNCED SHORTWAVE ENERGY LOCATED 
OFFSHORE THE MID-ATLANTIC COAST AT 14Z. ALTHOUGH SFC DEWPOINTS HAVE 
FALLEN INTO THE MID/UPPER 60S IN MOST AREAS AND LOW-LEVEL MOISTURE 
HAS CERTAINLY DECREASED IN COMPARISON TO YESTERDAY...SUFFICIENT LOW-
LEVEL MOISTURE STILL EXISTS FOR MARGINAL DIURNAL DESTABILIZATION 
WITH MLCAPE PROGGED IN THE 250-1000 J/KG RANGE...LOWEST NEAR THE VA 
BORDER AND HIGHEST NEAR THE SC BORDER. SHALLOW LOW-LEVEL CONVERGENCE 
ALONG THE STALLED FRONT SHOULD REMAIN SOUTH OF CENTRAL NC TODAY... 
AND WOULD BE MORE LIKELY TO SERVE AS A FOCUS FOR CONVECTIVE 
DEVELOPMENT OVER CENTRAL/UPSTATE SC WHERE GREATER DESTABILIZATION IS 
EXPECTED. CYCLONIC FLOW ALOFT WILL PERSIST OVER THE REGION 
TODAY...AND SUBSIDENCE IN THE WAKE OF EXITING SHORTWAVE ENERGY 
SHOULD EFFECTIVELY SUPPRESS DEVELOPMENT THROUGH AT LEAST MID 
AFTERNOON. ADDITIONAL SHORTWAVE ENERGY (UPSTREAM IN IL/IN AT 14Z) IS 
EXPECTED TO TRACK INTO THE SOUTHERN MID-ATLANTIC LATE THIS EVENING. 
DPVA ASSOC/W THIS FEATURE SHOULD OCCUR AT LEAST SEVERAL HRS AFTER 
PEAK HEATING (~03Z)...WITH NOCTURNAL COOLING FURTHER STABILIZING AN 
ALREADY MARGINAL THERMODYNAMIC ENVIRONMENT.

GIVEN LIMITED FORCING FOR ASCENT...A DRY MID/UPPER LEVEL AIRMASS AND 
VERY MARGINAL DESTABILIZATION...EXPECT A VERY LOW PROBABILITY FOR 
CONVECTIVE DEVELOPMENT TODAY...PERHAPS A SLIGHT CHANCE (10-20%) IN 
THE FAR SOUTHERN TIER OF COUNTIES IN THE WFO RAH CWA (I.E. ANSON 
EAST TO SAMPSON) DURING THE MID/LATE AFTERNOON. EXPECT HIGHS IN THE 
MID/UPPER 80S AND LOWS IN THE MID/UPPER 60S. -VINCENT

&&

.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... 
AS OF 325 AM FRIDAY...

EXPECT A LARGELY DRY DAY WITH INCREASED SUNSHINE. THE WEAKENING MID 
LEVEL TROUGH AXIS WILL SHIFT OFF THE COAST WITH MODEST HEIGHT RISES 
CONTINUING OVER NC. THE QUICKLY WEAKENING SURFACE FRONTAL ZONE NEAR 
THE NC/SC BORDER WILL FALL APART AND BE OVERTAKEN BY INCREASING LOW 
LEVEL SOUTHWEST FLOW AND DEVELOPMENT OF A WEAK PIEDMONT TROUGH. PW 
IS EXPECTED TO BE AT OR UNDER 1.2 INCHES TO START THE DAY... BUT IS 
FORECAST TO REBOUND TO AROUND 1.8 INCHES IN STRIP FROM CENTRAL VA 
THROUGH CENTRAL NC BY LATE AFTERNOON... WHICH THEN DRIFTS TO ERN NC 
SAT NIGHT. CORRESPONDINGLY THE MODELS DEPICT MODERATE INSTABILITY... 
MUCAPE OF 1000-1500 J/KG ON THE GFS LATE IN THE DAY... WITH AROUND 
1000 J/KG LINGERING IN THE FAR EAST OVERNIGHT. BUT THE MODELS 
GENERATE LITTLE MORE THAN AN ISOLATED SHOWER OR STORM AS THE COLUMN 
REMAINS WARM/STABLE AND DRY THROUGH THE 850-500 MB LAYER. WILL KEEP 
THE FORECAST DRY... AS ANY CONVECTION WOULD BE EXTREMELY ISOLATED. 
THICKNESSES REBOUND TO JUST 5-10 M BELOW NORMAL... WHICH WITH DECENT 
SUNSHINE SUPPORTS HIGHS OF 89-93. LOWS 69-74... MILDER THAN TONIGHT 
DUE TO THE RETURN OF HIGHER DEWPOINTS. -GIH

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/... 
AS OF 335 AM FRIDAY... 

MEDIUM RANGE GUIDANCE IS IN EXCELLENT AGREEMENT REGARDING THE  
DEVELOPMENT OF HIGH AMPLITUDE/UNSEASONABLY MERIDIONAL FLOW ACROSS 
NOAM THROUGH MID-WEEK - INCLUDING A DEEP TROUGH CENTERED NEAR 80-85W 
AND ASSOCIATED 3 STANDARD DEVIATION NEGATIVE HEIGHT ANOMALY CENTERED 
OVER THE LOWER OH VALLEY - WITH SLIGHT RETROGRESSION AND RELAXATION 
OF THE FLOW BY THE END OF THE PERIOD.  

SUN AND SUN NIGHT: HOT...WITH PROJECTED H85 TEMPERATURES AROUND 22-
23 C OVER THE CAROLINAS AS THE MID LEVEL RIDGE OVER THE DESERT SW 
AND PLAINS BUILDS BRIEFLY EAST IN ADVANCE OF THE AMPLIFYING TROUGH 
ALOFT.  THE FOCUS FOR CONVECTION WILL BE DIRECTED FROM THE LOWER OH 
VALLEY EAST ACROSS THE VIRGINIAS...WHERE THE AMPLIFYING TROUGH ALOFT 
WILL MAXIMIZE HEIGHT FALLS ALOFT/RIGHT JET ENTRANCE REGION 
DIVERGENCE. SOME OF THIS ACTIVITY MAY DEVELOP SOUTHWARD INTO THE 
NORTHERN AND WESTERN PIEDMONT LATE IN THE DAY AND ESPECIALLY DURING 
THE EVENING HOURS...AS BOTH LARGER SCALE FORCING AND OUTFLOW FROM 
UPSTREAM CONVECTION SPREADS SSE. FORECAST GUIDANCE SUGGESTS THE HOT 
AND DEEP DRY ADIABATICALLY-MIXED BOUNDARY LAYER WILL BE TOPPED BY 
STEEP (7 C/KM) LAPSE RATES ALL THE WAY THROUGH THE MID LEVELS. THE 
RESULT WILL BE MODERATE TO STRONG INSTABILITY AMIDST 30-35 KTS OF 
MID LEVEL FLOW...SUPPORTIVE OF MOSTLY MULTI-CELLULAR ORGANIZATION... 
WITH PERHAPS A FEW SUPERCELLS NEAR AND JUST NORTH OF THE VA BORDER. 
LARGE HAIL...AND DAMAGING WIND GUSTS AIDED BY SUB-CLOUD ACCELERATION 
OWING SFC DEWPOINT DEPRESSIONS OF 25-30 C KM...WILL POSE A SVR 
THREAT. THIS THREAT SHOULD BE MAXIMIZED INVOF THE VA BORDER...BEFORE 
INSTABILITY WANES AFTER SUNSET...AND SOUTHBOUND OUTFLOWS UNDERCUT 
STORMS WITH MEAN WIND-DRIVEN ENE STORM MOTIONS. WARM OVERNIGHT... 
WITH LOWS GENERALLY 73 TO 78 DEGREES.  

MON AND MON NIGHT: LOW PREDICTABILITY ASSOCIATED WITH MESOSCALE 
INFLUENCES (IE. OUTFLOW AND CLOUD COVER) FROM EARLIER CONVECTION SUN 
NIGHT...AS WELL AS THE LIKELIHOOD OF STRONG WESTERLY/DOWNSLOPE H85 
FLOW...COMPLICATE THE FORECAST FOR MON...DESPITE AN OTHERWISE STRONG 
SYNOPTIC SIGNAL FOR UPWARD VERTICAL MOTION OVER NC. THE DOWNSLOPE 
FLOW WILL LIKELY MIX OUT BL MOISTURE AND VEER THE LOW LEVEL FLOW 
WEST OF A LEE/PRE-FRONTAL SFC TROUGH INVOF US HWY 1...SUCH THAT ONLY 
A SLIGHT CHANCE POP IS WARRANTED THERE. BL MOISTURE AND CONVERGENCE 
WILL BE MORE PLENTIFUL TO THE EAST...WHERE POP WILL GRADUATE INTO 
THE LIKELY RANGE INVOF AND EAST OF I-95. CONTINUED STEEP LOW-MID 
LEVEL LAPSE RATES AMIDST STRENGTHENING MID LEVEL FLOW INTO THE 40-50 
KT RANGE WILL SUPPORT A GOOD CHANCE OF SVR STORMS...INCLUDING 
SUPERCELLS...CAPABLE OF PRODUCING LARGE HAIL AND DAMAGING WIND 
GUSTS. TORNADO PROBABILITIES WILL BE ONLY MARGINAL OWING TO LIMITED 
SRH (GENERALLY BELOW 150 M2/S2)...AND BL/LCL HEIGHTS AROUND 5 K FT. 

DRY AND COOLER CONDITIONS WILL PREVAIL THROUGH MID-WEEK...AS POST-
FRONTAL HIGH PRESSURE BUILDS INTO THE CENTRAL APPALACHIANS AND 
PRECIPITABLE WATER VALUES FALL BELOW AN INCH OVER CENTRAL NC. HIGHS 
AND LOWS ONLY IN THE LOWER TO MIDDLE 80S AND MID-UPPER 50S TO LOWER-
MID 60S...RESPECTIVELY...TUE-WED...BEFORE AIR MASS MODIFICATION 
THROUGH THE END OF THE WEEK. 

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... 
AS OF 1045 AM FRIDAY...

24-HR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE MAJORITY 
OF THE TAF PERIOD IN ASSOC/W A DRY AND SUBSIDENT AIRMASS IN THE WAKE 
OF THE RECENT COLD FRONTAL PASSAGE...WITH LIGHT/VARIABLE WINDS 
THROUGH TONIGHT. THE ONLY EXCEPTION TO THE ABOVE WILL BE A POTENTIAL 
FOR REDUCED VISBYS IN FOG OR LOW CEILINGS WITH STRATUS DURING THE 
PRE-DAWN HOURS SATURDAY MORNING (08-13Z)...AND A LOW CHANCE FOR AN 
ISOLD SHOWER OR STORM AT THE FAY TERMINAL LATE THIS AFTERNOON.

LOOKING AHEAD: EXPECT A CHANCE FOR AFTERNOON SHOWERS/STORMS OVER THE 
WEEKEND INTO EARLY NEXT WEEK...ESPECIALLY ON MONDAY WHEN THE 
ENVIRONMENT WOULD SUPPORT SEVERE THUNDERSTORMS DURING THE AFTERNOON 
AND EVENING HOURS. -VINCENT

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...VINCENT 
NEAR TERM...VINCENT 
SHORT TERM...HARTFIELD 
LONG TERM...MWS
AVIATION...VINCENT



National Weather Service Glossary of Abbreviations
Back to forecast page
Expanded Version (without abbreviations)

Units: English | Metric

Find the Weather for any City, State or Zipcode, or Country:

U.S. State List | Severe Weather | Tropical Storms | Ski Conditions
United States | Canada | Central America | South America | Asia | Europe | Australia | Africa | Islands

Weather Underground Copyright© 2014
Weather Underground, Inc.

Questions or Comments? Contact Us