Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 021848 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 248 PM EDT THU JUL 2 2015 .SYNOPSIS... A SURFACE TROUGH WILL LINGER OVER THE PIEDMONT THIS AFTERNOON. MEANWHILE...A COLD FRONT WILL SETTLE SLOWLY SOUTH AND STALL OVER THE MIDDLE ATLANTIC STATES TONIGHT THROUGH THE HOLIDAY WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1040 AM THURSDAY... INITIAL WEAK S/W LIFTING NEWD AND EXITING OUR COASTAL PLAIN COUNTIES AT 14Z. EARLIER ISOLATED SHOWER ACTIVITY HAS PRETTY MUCH DRIED UP AND EXTENSIVE DECK OF MID LEVEL CLOUDS HAS BEGUN TO ERODE/DIMINISH ACROSS THE AREA. WATER VAPOR IMAGERY DEPICTS A VORTICITY MAXIMUM OVER EASTERN TN. THIS SYSTEM CURRENTLY HANDLED WELL BY NEAR TERM MODELS. PARTIAL SUN OVER THE AREA EARLY THIS AFTERNOON SHOULD PRODUCE ADEQUATE SURFACE BASED INSTABILITY TO INITIATE/SUSTAIN CONVECTION. THE APPROACH OF THE MID LEVEL VORT MAX SHOULD ENHANCE THE CONVECTION SO THAT WE SHOULD SEE DECENT COVERAGE OF CONVECTION...PRIMARILY OVER THE WESTERN AND NORTHERN PIEDMONT WHERE THE 12Z 850MB ANALYSIS DEPICTS AN ELONGATED SW-NE ORIENTATED TROUGH. LATEST SPC MESO SCALE ANALYSIS DEPICTS MODEST BULK SHEAR ON THE ORDER OF 20-25KTS OVER A SMALL PART OF THE PIEDMONT. ENOUGH SHEAR MAY EXIST TO CAUSE CONVECTION TO FORM IN BROKEN BANDS WHICH MAY CONTRIBUTE TO AN INCREASE RISK FOR STRONG/LOCALLY DAMAGING WIND GUSTS. TEMPS THIS AFTERNOON STILL APPEAR ON TRACK TO REACH THE MID-UPPER 80S. HOWEVER...IF CONVECTION BECOMES SCATTERED PRIOR TO 19Z...SOME PLACES MAY SEE MAX TEMPS NEAR 80/LOWER 80S. -WSS TONIGHT: INITIAL SHOWERS AND STORMS WILL GRADUALLY DIMINISH/MOVE ENE THIS EVENING. HOWEVER...A TRAILING SHORTWAVE TROUGH AND SEPARATE CONVECTIVE CLUSTER/MCV OVER THE NORTHERN PLAINS THIS MORNING WILL AMPLIFY... AMIDST CONTINUED CYCLONIC FLOW ALOFT...INTO THE TN VALLEY AND SOUTHERN-CENTRAL APPALACHIANS BY FRI MORNING. ASSOCIATED RENEWED FORCING FOR ASCENT WILL PROVIDE FOR SHOWER AND STORM REDEVELOPMENT OR MAINTENANCE FROM UPSTREAM...PARTICULARLY OVER THE NORTHERN PIEDMONT/NEAR THE VA BORDER...IN CLOSEST PROXIMITY TO THE SYNOPTIC/DEEPER FRONTAL ZONE FORECAST TO SETTLE SOUTH THROUGH VA DURING THE NEXT 24 HOURS. CONSIDERABLE CLOUDINESS OVERNIGHT WILL LIKELY RESULT IN LOW TEMPERATURES A DEGREE OR TWO ABOVE GUIDANCE - 69-74. && .NEAR TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 425 AM THURSDAY... WHILE THE MODELS INDICATE THE SYNOPTIC FRONTAL ZONE WILL REMAIN NEAR THE VA BORDER...NUMEROUS OUTFLOW BOUNDARIES WILL MODULATE THE EFFECTIVE FRONT AND LIKELY CAUSE IT TO SAG SOUTH INTO CENTRAL NC THIS PERIOD. CONVERGENCE AND DIFFERENTIAL HEATING ABOUT THE FRONT(S); THE EASTWARD MIGRATION OF THE AFOREMENTIONED SHORTWAVE TROUGH ACROSS THE CENTRAL APPALACHIANS; AND LOWER THAN PREVIOUS DAYS LCL/LFC HEIGHTS AND CINH...WILL SUPPORT THE DEVELOPMENT OF NUMEROUS SHOWERS AND STORMS BY MIDDAY-EARLY AFTERNOON. CONTINUED SEASONABLY STRONG MID LEVEL FLOW AROUND 30 KTS WILL SUPPORT ADDITIONAL MULTI- CELL STORM ORGANIZATION WITH AN ATTENDANT PRIMARY THREAT OF DAMAGING WET MICROBURST WIND GUSTS...AND LOCALIZED FLOODING FOR STORMS TRAINING ALONG THE GENERALLY EAST TO WEST-ORIENTED FRONT/OUTFLOW. HOWEVER...A FEW STORMS MAY DISPLAY TRANSIENT SUPERCELL/ROTATIONAL CHARACTERISTICS OWING TO ENHANCED LOW LEVEL SHEAR INVOF THE BOUNDARY. WHILE THE BRUNT OF THE SHOWERS AND STORMS ARE LIKELY TO MOVE NE OF CENTRAL NC IN ASSOCIATION WITH A FRONTAL WAVE FORECAST TO TRACK ALONG THE FRONT AND OFFSHORE THE VA COAST FRI NIGHT...HIGH PWAT VALUES AND MINIMAL CINH...DESPITE PRIOR CONVECTIVE OVERTURNING/WEAK INSTABILITY...WARRANTS A CONTINUED SLIGHT-LOW CHANCE OF SHOWERS AND STORMS OVERNIGHT. LOWS IN THE UPPER 60S TO LOWER 70S. && .LONG TERM /SATURDAY THROUGH THURSDAY/...
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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.
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&& .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 140 PM THURSDAY... WHILE VFR CONDITIONS WILL GENERALLY PREDOMINATE ACROSS CENTRAL NC THROUGH FRIDAY AFTERNOON...SCATTERED CONVECTION THIS AFTERNOON THROUGH THIS EVENING...AND AGAIN ON FRIDAY WILL CAUSE PERIODS OF MVFR CEILING AND VISIBILITIES. IN VICINITY OF THE STORMS...EXPECT GUSTY WINDS WITH GUSTS 30-40KTS LIKELY. A STALLED SURFACE FRONT NEAR THE VIRGINIA BORDER COUPLED WITH A SERIES OF UPPER LEVEL DISTURBANCES WILL CAUSE PERIODS OF SHOWERS AND STORMS ACROSS CENTRAL NC THROUGH TUESDAY. THE SCATTERED CONVECTION WILL BE MOST LIKELY IN THE AFTERNOON AND EVENING HOURS. IN VICINITY OF THE SHOWERS AND STORMS...EXPECT BRIEF INTERVALS OF MVFR CONDITIONS ALONG WITH WIND GUSTS UP TO 40 KTS. AT THIS TIME...IT APPEARS THAT THE CONVECTIVE COVERAGE WILL BE MOST NUMEROUS ON FRIDAY AND AGAIN MONDAY. && ..RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...26 NEAR TERM...WSS/26 SHORT TERM...26 LONG TERM...RAH AVIATION...WSS

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