Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 311852 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 252 PM EDT FRI JUL 31 2015 .SYNOPSIS...A COLD FRONT WILL STALL OVER SOUTHEAST NORTH CAROLINA THIS AFTERNOON...AND LINGER IN THIS REGION THROUGH THE WEEKEND. WEAK HIGH PRESSURE WILL BUILD INTO THE PIEDMONT AND PERSIST THROUGH THE WEEKEND. && .NEAR TERM /THROUGH SATURDAY NIGHT/... AS OF 1015 AM FRIDAY... MAIN ADJUSTMENT IN THE NEAR TERM FORECAST WAS TO DWINDLE PRECIP CHANCES A BIT OVER THE SE COUNTIES. 12Z UPPER AIR ANALYSIS DEPICTS A DRIER SLIGHTLY MORE STABLE AIR MASS FILTERING INTO CENTRAL NC. ANTI-CYCLONIC FLOW NOTED OVER THE BULK OF THE REGION AT 925-850MB WHILE MOISTURE BECOMING LIMITED BELOW 600MB. PER MESO ANALYSIS...APPEARS ENOUGH RESIDUAL MOISTURE WILL EXITS ALONG A WILSON-LAURINBURG LINE SOUTHWARD TO RETAIN A SLIGHT-SMALL CHANCE POP LATER THIS AFTERNOON-EARLY EVENING. FARTHER NORTH AND WEST...ATMOSPHERE APPEARS TOO DRY AND FORCING LIMITED TO HEATING SO A POP LESS THAN 20 PERCENT SHOULD SUFFICE. SLIGHTLY WARMER THAN PREDICTED TEMPS AT 850MB SUPPORT THE FORECAST OF AFTERNOON TEMPS IN THE 90-95 DEGREE RANGE. ACROSS MOST OF THE PIEDMONT...LOW LEVEL NLY FLOW WILL ADVECT A DRIER DEWPOINTS WITH MID AFTERNOON DEWPOINTS IN THE UPPER 50S TO AROUND 60 HIGHLY PROBABLE. THUS...IT WILL FEEL LESS HUMID (AND THE HEAT SLIGHTLY MORE TOLERABLE) COMPARED TO THE PAST FEW DAYS. TONIGHT...ANY LINGERING CONVECTION OVER THE SE COUNTIES SHOULD DIMINISH SHORTLY AFTER SUNSET. RESIDUAL LOW LEVEL MOISTURE MAY LEAD TO PATCHES OF LIGHT FOG IN VICINITY OF KFAY...KGSB...AND KCTZ BY EARLY SATURDAY. ELSEWHERE EXPECT FAIR-PARTLY CLOUDY SKIES. MIN TEMPS LOW-MID 60S NW TO LOWER 70S SE. -WSS SAT/SAT NIGHT: A QUIET DAY AS THE MEAN TROUGH AXIS HOLDS OVERHEAD... WITH THE SURFACE FRONTAL ZONE STRETCHING THROUGH ERN AND SE NC AS HIGH PRESSURE BUILDS IN FROM THE WNW. EXPECT A ROUND OF ISOLATED MID- LATE AFTERNOON SHOWERS AND STORMS OVER THE FAR SE WITHIN MARGINAL INSTABILITY AND WEAK LOW LEVEL MASS CONVERGENCE... WITH DRY WEATHER ELSEWHERE GIVEN THE DRY AND SUBSIDING MID LEVELS AND FALLING PW VALUES. AGAIN LEANING TOWARD A DRY ADIABATIC LOW LEVEL LAPSE RATE... EXPECT HIGHS OF 90-95... WITH LOWS SAT NIGHT 63-70. -GIH && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 200 AM FRIDAY... A STAGNANT UPPER LEVEL PATTERN WILL REMAIN IN PLACE ON SUNDAY AND MONDAY WITH A SLIGHTLY DEEPENING UPPER LEVEL TROUGH OVER THE EASTERN CONUS AND NEAR STATIONARY RIDGE OVER THE SOUTHWESTERN UNITED STATES. DURING THIS PERIOD A WEAK SURFACE HIGH OVER THE OHIO VALLEY WILL KEEP CONDITIONS RELATIVELY DRY. TO THE NORTH...A LOW PRESSURE SYSTEM NORTH OF THE GREAT LAKES WITH AN ASSOCIATED FRONTAL SYSTEM STRETCHING SOUTHWARD...WILL IMPINGE UPON THE SURFACE HIGH BY THE END OF THE SHORT TERM... HELPING TO WEAKEN THE HIGH BUT SHOULD STILL REMAIN DRY IN THE NORTHWEST PIEDMONT. THE ONLY CHANCE FOR PRECIPITATION WILL COME IN THE FORM OF POTENTIAL DIURNAL CONVECTION...PARTICULARLY IN THE FAR SOUTHEAST WHERE RETURN FLOW AROUND THE BERMUDA HIGH WILL BRING INCREASED MOISTURE INTO THE AREA WHICH COULD USE THE SEA BREEZE FRONT AS A CATALYST FOR CONVECTION DURING THE AFTERNOON/EARLY EVENING HOURS. REGARDLESS...THE AIRMASS AS A WHOLE WILL BE VERY DRY FOR THIS TIME OF YEAR WHICH WILL KEEP PRECIP CHANCES VERY LOW. HIGH TEMPERATURES WILL BE IN THE LOWER 90S WITH LOWS IN THE UPPER 60S NW TO LOW 70S SE. DEWPOINTS WILL MODERATE FROM THE LOWER 60S ON SUNDAY TO MID TO UPPER 60S BY MONDAY...RESULTING IN AND OVERALL INCREASE IN HUMIDITY. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 245 PM FRIDAY... THE LATEST 12Z MODEL GUIDANCE IS IN RELATIVELY GOOD AGREEMENT W/REGARD TO THE EVOLUTION OF THE UPPER LEVEL PATTERN NEXT WEEK. THE DEEP UPPER LEVEL RIDGE CURRENTLY CENTERED OVER THE WESTERN CONUS /INTERMOUNTAIN WEST/ WILL GRADUALLY SHIFT EASTWARD TO THE ROCKIES BY THE MIDDLE OF NEXT WEEK...AND AS THE RIDGE AXIS SHIFTS EAST...A MORE ACTIVE /ENERGETIC/ PATTERN OF NORTHWEST FLOW ALOFT WILL DEVELOP DOWNSTREAM OVER THE OH VALLEY/MID-ATLANTIC. FROM A PATTERN RECOGNITION STANDPOINT...ONE WOULD EXPECT ABOVE NORMAL TEMPERATURES (MID 90S) AND BELOW NORMAL CHANCES FOR CONVECTION TO PERSIST THROUGH EARLY NEXT WEEK...TRANSITIONING TO NEAR NORMAL TEMPERATURES AND AT/ABOVE NORMAL CHANCES FOR CONVECTION BY MID/LATE NEXT WEEK. GIVEN THAT ENHANCED CONVECTIVE COVERAGE/TIMING WILL BE HIGHLY SENSITIVE TO THE PRECISE EVOLUTION OF SMALL AMPLITUDE WAVES...UPSTREAM CONVECTION (I.E. MCS ACTIVITY)...AND/OR CONVECTIVE REMNANTS (I.E. OUTFLOW/ MCV`S)...IT IS DIFFICULT IF NOT IMPOSSIBLE TO DETERMINE FORECAST SPECIFICS (CONVECTIVE TIMING/COVERAGE/INTENSITY) MID TO LATE NEXT WEEK. GIVEN THAT STRONGER DEEP LAYER SHEAR AND STEEPER MID-LEVEL LAPSE RATES (I.E. MODIFIED EML) ARE MORE LIKELY TO BE PRESENT IN A SYNOPTIC PATTERN CHARACTERIZED BY NW FLOW ALOFT...AN ENHANCED POTENTIAL FOR SEVERE THUNDERSTORMS MAY BE PRESENT AT SOME POINT IN THE WED-FRI TIME FRAME...PRIMARILY IF DIURNAL TIMING IS FAVORABLE W/REGARD TO APPROACHING SHORTWAVE ENERGY. -VINCENT && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... AS OF 145 PM FRIDAY... THERE IS HIGH CONFIDENCE THAT VFR CONDITIONS WILL PERSIST ACROSS CENTRAL NC THROUGH 12Z SUNDAY. THE EXCEPTION WILL BE A BRIEF INSTANCE OF MVFR VISIBILITY DUE TO FOG EARLY SATURDAY MORNING IN VICINITY OF KFAY. OTHERWISE SURFACE WINDS WILL BE LIGHT AND VARIABLE. VFR CONDITIONS WILL PREVAIL THROUGH MOST OF THE UPCOMING WEEK. THERE WILL BE AN INCREASE IN THE POTENTIAL FOR EARLY MORNING FOG AND LOW CLOUDS AS THE LOWER LEVELS OF THE ATMOSPHERE BECOME INCREASINGLY MOIST...AS WELL AS A THREAT FOR SCATTERED CONVECTION IN THE AFTERNOON AND EARLY EVENING HOURS...ESPECIALLY BEYOND MONDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS/HARTFIELD SHORT TERM...ELLIS LONG TERM...VINCENT AVIATION...WSS

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