Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 011007 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 610 AM EDT FRI MAY 1 2015 .SYNOPSIS...LOW PRESSURE WILL LINGER OVER AND JUST OFF THE CAROLINA COAST TODAY... AS A STRONG UPPER LEVEL DISTURBANCE CROSSES THE REGION. THE LOW AND DISTURBANCE WILL MOVE OFFSHORE LATE TONIGHT... AND HIGH PRESSURE WILL BUILD IN FROM THE WEST OVER THE WEEKEND. && .NEAR TERM /TODAY/... AS OF 610 AM FRIDAY... HAVE UPDATED THE FORECAST FOR CATEGORICAL POPS FOR WIDESPREAD SHOWERS AND ISOLATED STORMS ACROSS THE NORTH THROUGH MID AFTERNOON... WITH LESSER POPS ACROSS THE SOUTH. THE LATEST HRRR GUIDANCE AND OBSERVED TRENDS SUPPORT CONTINUED REDEVELOPMENT OF SHOWERS OVER THE NRN TWO THIRDS OF CENTRAL NC FOR THE NEXT 6-9 HRS... FOSTERED BY HIGHER-THAN-EXPECTED LOW- AND MID-LEVEL LAPSE RATES (THE LATTER BEING 7.0-7.5 C/KM) AND INTENSE DPVA. FREEZING LEVELS ARE DOWN TO AROUND 7 KFT WITH -20C HEIGHTS OF 16-17 KFT... SO A FEW OF THESE STRONGER CELLS COULD GENERATE ISOLATED SMALL HAIL. PREVIOUS DISCUSSION FROM 240 AM: ONE LAST UNSETTLED DAY... AS AN UPPER LOW TRAVERSES THE REGION. THIS LOW IS EASILY SEEN ON WATER VAPOR IMAGERY OVER FAR NW NC AND SW VA... AS IS A VORTICITY LOBE NOW PUSHING THROUGH CENTRAL NC AND SUPPORTING AN ACCOMPANYING BAND OF RAIN. AS ADDITIONAL VORTICITY MAXIMA ROTATE AROUND THE SOUTH SIDE OF THE LOW TODAY AS IT SLOWLY CROSSES THE REGION... DEVELOPMENT OF ADDITIONAL SHOWERS IS LIKELY. THE BEST COVERAGE SHOULD BE ACROSS THE NRN AND ERN CWA... WHERE THE BETTER LOW LEVEL MASS CONVERGENCE AND MID LEVEL DPVA AND DEFORMATION WILL BE FOUND. WILL HAVE PEAK POPS AT 50-80% S TO N... WITH PW VALUES JUST SLIGHTLY ABOVE NORMAL. AN ISOLATED STORM REMAINS POSSIBLE BENEATH THE COLD POOL ALOFT WHERE 500 MB WILL BE -20C TO -23C... BUT DON`T EXPECT QUITE THE ORGANIZED CONVECTION WE SAW YESTERDAY AS MID LEVEL LAPSE RATES SHOULD BE A BIT LOWER... 6.5 C/KM INSTEAD OF THE VALUES CLOSER TO 7.0 C/KM THAT WE SAW THU. PRECIP WILL SHIFT INTO THE EASTERN CWA DURING THE AFTERNOON WITH GRADUALLY DECREASING COVERAGE AS THE LOW MOVES TO OUR EAST. THE ONSET OF MIXING WILL PARTIALLY TAP INTO 20-30 KTS WINDS WITHIN A PASSING 850 MB NORTHEASTERLY JETLET... SO EXPECT A FEW GUSTS FROM LATE MORNING THROUGH THE AFTERNOON. THICKNESSES AND STATISTICAL GUIDANCE FACTORING IN THICK CLOUD COVER FOR MUCH OF THE DAY SUPPORTS CHILLY HIGHS IN THE LOW-MID 60S. -GIH && .SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/... AS OF 255 AM FRIDAY... TONIGHT: EXPECT SLOW CLEARING WITH MODEST BUT DEEP SUBSIDENCE AND DRYING IN THE WAKE OF THE EXITING LOW. SURFACE WINDS WILL BECOME FAIRLY LIGHT FROM THE NNW WHILE 950-850 MB WINDS WILL BE MAINLY FROM THE NNE... ALLOWING ATLANTIC MOISTURE TO CONTINUE TO SPILL IN ON THE NW SIDE OF THE LOW... SO SCATTERED STRATOCU MAY LINGER WELL INTO THE NIGHT. LOWS 45-50 WITH WEAK COOL AIR ADVECTION AS SURFACE HIGH PRESSURE ATTEMPTS TO BUILD IN FROM THE WEST... BUT INITIALLY GETS HELD UP BY THE MOUNTAINS. SAT/SAT NIGHT: MOSTLY DRY AND QUIET WEATHER IS EXPECTED. A BAND OF ISOLATED SHOWERS IS EXPECTED OVER THE NRN/ERN PORTIONS OF CENTRAL NC IN THE AFTERNOON... AS A NOSE OF ENHANCED PW AND WEAK VORTICITY DROPS TO THE SSE AROUND THE WEST SIDE OF THE OFFSHORE LOW. MOISTURE IS UNIMPRESSIVE HOWEVER... WITH VERY SMALL FORECAST MUCAPE... SO WILL MAINTAIN JUST ISOLATED COVERAGE... FOCUSED ON THE NW PIEDMONT AND NRN/CENTRAL COASTAL PLAIN... AS SUGGESTED BY THE HI-RES WRF MODEL RUNS. EXPECT MOSTLY CLEAR SKIES SAT NIGHT WITH WINDS BECOMING LIGHT/VARIABLE AS THE CENTER OF THE SURFACE HIGH SHIFTS OVERHEAD. HIGHS 71-76 NE TO SW... AND LOWS IN THE UPPER 40S TO LOWER 50S. -GIH && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 230 AM FRIDAY... THE LONG TERM WILL FEATURE WARM AND DRY CONDITIONS WITH OUR FIRST REAL STRETCH OF 80 DEGREE DAYS OF THE YEAR. THE PATTERN WILL FEATURE SURFACE HIGH PRESSURE OFFSHORE WITH WEAK SOUTHERLY RETURN FLOW ACROSS CENTRAL NC. THE NORTHWESTERLIES ALOFT WILL WEAKEN CONSIDERABLY TO VERY LIGHT WINDS FOR THE FIRST HALF OF THE WEEK. IN FACT THE GFS FORECAST SOUNDING FOR GREENSBORO ON MONDAY AFTERNOON HAS LESS THAN 10 KTS OF WIND ALL THE WAY UP THROUGH 200 MB. WHILE THE TEMPERATURES WILL FEEL VERY WARM IN CONTRAST TO WHAT WE HAVE BEEN EXPERIENCING THIS PAST WEEK...THE LOW TO MID 80S WILL ONLY BE ABOUT 5 DEGREES ABOVE NORMAL FOR THIS TIME OF THE YEAR AND NOT EVEN CLOSE TO APPROACHING RECORDS AS THESE ARE ALL IN THE LOW TO MID 90S. LOWS WILL BE IN THE UPPER 50S TO LOW 60S. NOT MUCH IN THE WAY OF PRECIPITATION IS EXPECTED DURING THE PERIOD BUT SOME CONVECTION ASSOCIATED WITH A TROUGH NORTHWEST OF THE AREA COULD IMPINGE ON THE TRIAD ON WEDNESDAY AND THURSDAY AFTERNOONS BUT COVERAGE...AND DURATION SHOULD BE MINIMAL AS MOST ACTIVITY SHOULD REMAIN NORTH OF THE AREA. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 105 AM FRIDAY... MVFR CONDITIONS WILL DOMINATE CENTRAL NC TAFS OVERNIGHT AND THROUGH FRI MORNING... FOLLOWED BY SLOW IMPROVEMENT TO VFR MID-LATE FRI AFTERNOON (AFTER 18Z). A STRONG UPPER LEVEL LOW MOVING OVER THE REGION THROUGH TODAY WILL BRING UNSETTLED WEATHER WITH MVFR CIGS COMMON AT ALL SITES... AND PERIODS OF VFR-MVFR VSBYS IN SHOWERS... ESPECIALLY FROM MID MORNING THROUGH THE AFTERNOON HOURS. CIGS MAY DROP TO IFR FOR A FEW HOURS EARLY THIS MORNING BETWEEN 07Z AND 13Z. AN ISOLATED THUNDERSTORM OR TWO IS ALSO POSSIBLE AT THE EASTERN TERMINALS OF RWI/FAY 15Z-20Z TODAY... BUT THE COVERAGE SHOULD BE TOO LOW TO MENTION IN THE TAFS. WINDS WILL INCREASE THIS MORNING FROM THE NORTH OR NE AT 10-14 KTS GUSTING UP TO 20 KTS... THEN DROP BACK UNDER 10 KTS AFTER 22Z. VFR CONDITIONS ARE LIKELY THIS EVENING ON THROUGH TONIGHT. LOOKING BEYOND 06Z EARLY SAT MORNING: VFR CONDITIONS LIKELY SAT MORNING THROUGH TUE... AS HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST... SHIFTING OVERHEAD LATE IN THE WEEKEND AND MOVING OFFSHORE EARLY NEXT WEEK. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...ELLIS AVIATION...HARTFIELD

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