Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 030642 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 242 AM EDT FRI JUL 3 2015 .SYNOPSIS... SURFACE LOW PRESSURE WILL TRACK EAST ACROSS NC AND VA LATER TODAY AND TONIGHT...ALONG A FRONTAL ZONE THAT WILL LINGER OVER THE REGION THROUGH THE HOLIDAY WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM THURSDAY... ONLY A SMALL LINE OF SHOWERS/ISOLATED THUNDERSTORMS REMAINED FROM NEAR TROY TO NEAR CLAYTON... MOVING SLOWLY E-NE AT 1000 PM. THIS AREA STRETCHES ALONG THE OLD OUTFLOW BOUNDARY. A RECENT UPTICK IN SHOWERS ALONG THIS BOUNDARY WAS OCCURRING WITH LOW TOPPED CONVECTION... VERY LITTLE CG LIGHTNING. WE WILL FOLLOW THE MESO- ANALYSIS AND RADAR TRENDS WHICH INDICATE AN AREA OF WEAK SURFACE MOISTURE CONVERGENCE IN THIS REGION ALONG WITH SOME RESIDUAL MLCAPES AROUND 500-1000 J/KG AND KEEP LIKELY POP GOING A BIT LONGER. TRENDS DO SUGGEST LOCALLY 1 TO 2 INCHES OF ADDITIONAL RAINFALL FROM NEAR CLAYTON TO WILSON AND SOUTH OF TARBORO IN A NARROW AXIS. SOME TRAILING LOW TOPPED CONVECTION MAY GET GOING FOR A FEW HOURS ALONG THE WEST EDGE OF THE OUTFLOWS AS WELL BACK OVER IN THE NW PIEDMONT. OTHERWISE... THE ORGANIZED CONVECTION HAS ROUGHLY MOVED OFFSHORE AND WAS APPROACHING THE WESTERN SLOPES OF THE APPALACHIANS FROM THE TN VALLEY. THE ACTIVITY OVER THE TN VALLEY MAY HOLD TOGETHER INTO THE MOUNTAINS. OTHERWISE... CONDITIONS ARE LESS FAVORABLE NOW EAST OF THE MOUNTAINS. WE WILL CARRY A SLIGHT CHANCE OVERNIGHT. PARTLY CLOUDY TO MOSTLY CLOUDY SKIES ARE EXPECTED WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 300 PM THURSDAY... FRIDAY...WATER VAPOR IMAGERY THIS AFTERNOON DEPICTS A WELL DEFINED CONVECTIVELY INDUCE VORT MAX MOVING SEWD ON THE BACKSIDE OF THE BAGGY UPPER LEVEL TROUGH. MODEL GUIDANCE HAS A FAIRLY GOOD HANDLE ON THIS FEATURE. THIS SYSTEM PROJECTED TO ROUND THE BASE OF THE TROUGH LATE TONIGHT/EARLY FRI THEN CROSS THE CAROLINAS LATER FRIDAY. BASED ON CURRENT TIMING...SHOULD SEE SCATTERED CONVECTION DEVELOP A FEW HOURS EARLIER THAN NORMAL...POSSIBLY AS EARLY AS 10-11 AM...WITH THE MAJORITY OF THE CONVECTION OCCURRING BETWEEN NOON AND 8 PM. THE LOW LEVEL ATMOSPHERE EXPECTED TO BE SLIGHT-MODERATELY UNSTABLE ALONG WITH EFFECTIVE BULK SHEAR VALUES APPROACHING 30KTS... SUPPORTIVE OF ORGANIZED CONVECTION. WIND PROFILE FAIRLY UNIDIRECTIONAL (SW) SO EXPECT CONVECTION TO EVOLVE INTO BROKEN BANDS...PRODUCING STRONG/LOCALLY DAMAGING WINDS. MAX TEMPS FRIDAY DEPENDENT ON WHEN CONVECTION DEVELOPS AND EXTENT OF CLOUD COVER OVERHEAD. EXPECT MORE CLOUDS THAN SUN NORTH AS WELL AS MORE CONVECTION ACROSS THE NORTH SO SHOULD SEE A TEMP RANGE OF LOW- MID 80S NORTH TO UPPER 80S/AROUND 90 SOUTH. EARLIER INITIATION OF CONVECTION WILL LIKELY HAVE AN EFFECT ON MAX TEMPS (2-3 DEGREES COOLER). CURRENTLY APPEARS BULK OF ENERGY ASSOCIATED WITH THE VORT MAX EXITS OUR REGION BY EARLY EVENING. THIS SUGGEST THAT CONVECTION SHOULD SLOWLY WANE/DIMINISH BETWEEN 7-10 PM ACROSS THE REGION. SIMILAR TO TONIGHT...PRESENCE OF OF A MOIST AIR MASS...A STALLED LOW LEVEL TROUGH AND PERTURBATIONS ALOFT SUGGEST A FEW SHOWERS MAY LINGER INTO THE OVERNIGHT HOURS. MIN TEMPS UPPER 60S-LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 245 PM FRIDAY... THE GENERAL OVERALL PATTERN WILL BE DOMINATED BY GENERAL TROUGHINESS IN THE UPPER LEVELS OVER THE EASTERN U.S. WITH A FEW SHORTWAVE DISTURBANCES PROGRESSING THROUGH THE AREA. AT THE SURFACE...A STALLED BOUNDARY WILL LINGER IN THE VICINITY OF CENTRAL NC...WITH GENERALLY LOW PRESSURE OVER THE AREA THROUGH THE PERIOD. WHAT THIS MEANS WEATHER-WISE IS THE TYPICAL SUMMERTIME HIGHER CHANCES FOR CONVECTION DURING THE DAY/EVENING HOURS AND LESS OVERNIGHT/EARLY MORNING. HOWEVER...SMALL VARIATIONS IN THIS PATTERN WILL HAVE BIG IMPACTS ON THE CHANCES...TIMING...AND LOCATION OF CONVECTION...THUS CONFIDENCE IS STILL NOT TERRIBLY HIGH IN THAT RESPECT. AS OF THE LATEST MODEL RUNS...HIGHEST PRECIP CHANCES WILL BE ON SUNDAY. TEMPERATURE-WISE: HIGHS WILL GENERALLY BE IN THE MID 80S TO LOW 90S THROUGH THE PERIOD...WITH OVERNIGHT LOWS STEADY IN THE UPPER 60S TO LOW 70S. FORECAST SOUNDINGS CONTINUE TO INDICATE PW`S IN THE 1.5-2 INCH RANGE THROUGH THE PERIOD...THUS THERE IS STILL THE THREAT OF SOME MINOR FLOODING RESULTING FROM DEVELOPING STORMS. AS OF THIS AFTERNOON...CENTRAL NC IS UNDER JUST A GENERAL THUNDER THREAT FOR SATURDAY. A SHORTWAVE TRAVERSING THE AREA ON MONDAY MAY BRING THE BEST CHANCE FOR STRONG STORMS...WITH GFS BUFR SOUNDINGS INDICATING MODEST INSTABILITY...BUT WEAK SHEAR. GIVEN HOW THINGS CAN CHANGE BETWEEN NOW AND THEN...WILL LEAVE MENTION OUT OF HWO FOR NOW. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 230 AM FRIDAY... THE PRESENCE OF A SURFACE FRONT DRAPED ACROSS THE NORTHERN NC PIEDMONT --AND ASSOCIATED MOISTURE CONVERGENCE-- WILL LIKELY RESULT IN THE CONTINUED DEVELOPMENT AND LOWERING OF IFR-MVFR STRATUS THIS MORNING. THE STRATUS CLOUDS WILL GRADUALLY LIFT AND MORPH AFTER DAYBREAK INTO A CUMULUS FIELD...WHOSE BASES ARE APT TO FLIRT WITH THE 3000 FT/MVFR THRESHOLD THROUGH MIDDAY-EARLY AFTERNOON. PRIOR CONVECTION AND ASSOCIATED AIR MASS STABILIZATION OVER CENTRAL NC WILL CAUSE UPSTREAM CONVECTION CROSSING THE SOUTHERN APPALACHIANS TO WEAKEN AS IT APPROACHES...THOUGH A FEW REMNANT SHOWERS CANNOT BE RULED OUT IN THE 10-16Z TIME FRAME. HOWEVER...A BETTER CHANCE OF SHOWERS AND STORMS WILL OCCUR WITH THE COMBINATION OF DIURNAL HEATING AND THE APPROACH OF A DISTURBANCE ALOFT INITIALLY OVER THE WESTERN TN VALLEY...AND AND INTERACTION WITH THE AFOREMENTIONED FRONTAL ZONE...BETWEEN 16Z-00Z. OUTLOOK: THE AFOREMENTIONED FRONT WILL STALL OVER VA/NC AND RESULT IN ABOVE AVERAGE PROBABILITIES OF SHOWERS AND STORMS AND ASSOCIATED SUB-VFR CONDITIONS THROUGH MON...WITH THE RELATIVE HIGHEST PROBABILITY SUN-MON. PERIODS OF MVFR CEILINGS WILL BE POSSIBLE EVEN OUTSIDE OF STORMS DURING THAT TIME...ESPECIALLY DURING THE MORNING TO EARLY AFTERNOON HOURS. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...PWB SHORT TERM...WSS LONG TERM...RAH AVIATION...26

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