Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 050648 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 247 PM EDT TUE MAY 5 2015 .SYNOPSIS...BERMUDA HIGH PRESSURE WILL EXTEND INTO OUR REGION THROUGH MID WEEK. AN AREA OF LOW PRESSURE WILL FORM NEAR THE BAHAMAS AND MEANDER OFF THE SOUTHEAST COAST DURING THE MIDDLE OF THE WEEK. && .NEAR TERM /TONIGHT/... AS OF 1015 PM MONDAY... BENEATH 850-700 MB RIDGING CENTERED OVER THE SOUTHERN APPALACHIANS AND CAROLINAS THIS EVENING...BERMUDA HIGH PRESSURE WILL CONTINUE TO EXTEND WEST ACROSS OUR REGION. THE FLOW AROUND THE RIDGE WILL MAINTAIN A LIGHT SOUTHERLY WIND...WITH TEMPERATURES ON AVG ABOUT A CATEGORY HIGHER THAN THOSE OF MON MORNING OWING TO A SLIGHTLY TIGHTER MSL PRESSURE GRADIENT AROUND THE NOW MORE DISTANT SFC HIGH - IN THE 50S. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... AS OF 245 PM MONDAY... HIGH PRESSURE WILL REMAIN IN PLACE OFFSHORE OF THE CAROLINAS ON TUESDAY. MEANWHILE A COLD FRONT WILL MOVE INTO THE VICINITY OF THE MASON-DIXON LINE AND A SHALLOW UPPER TROUGH OVER THE GULF OF MEXICO WILL DRIFT EAST ACROSS THE FLORIDA. BETWEEN THESE FEATURES...THE ONLY FORCING FOR CONVECTION WILL BE DIFFERENTIAL HEATING ALONG THE MOUNTAIN SLOPES AND A DEVELOPING LEE TROUGH THAT SHOULD REMAIN WEST OF THE TRIAD. FORECAST SOUNDINGS SHOW ANOTHER DAY OF RELATIVELY DEEP MIXING AND LITTLE POTENTIAL FOR INSTABILITY. WHAT CONVECTION THAT DOES FORM TO THE NORTH AND WEST WILL ENCOUNTER A NORTHEASTERLY STEERING FLOW THAT SHOULD FURTHER HELP TO KEEP ANY SHOWERS/STORMS WEST OF THE TRIAD. HIGHS AGAIN IN THE LOWER 80S...MAYBE A DEGREE WARMER THAN TODAY BASED ON A SLIGHT UPTICK IN 1000-850MB THICKNESSES BY 5M OR SO. ANOTHER MOSTLY CLEAR NIGHT EXPECTED ON TUESDAY NIGHT AS LINGERING CLOUD COVER FROM CONVECTION OVER VIRGINIA SHOULD HOLD TO OUR NORTH. SOME VERY THIN HIGH CLOUDS MAY BEGIN TO FILTER IN FROM THE SOUTH AS A SUB-TROPICAL LOW BEGINS TO DEVELOP NEAR THE BAHAMAS. LOWS AGAIN MOSTLY IN THE MID-60S. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 247 AM TUESDAY... THERE IS HIGH CONFIDENCE IN THE OVERALL PATTERN OF UPPER LEVEL RIDGING OVER THE EASTERN UNITED STATES LATE THIS WEEK THROUGH THE WEEKEND... THE TROUGHING OUT WEST. HOWEVER... MODELS STILL LIKELY DO NOT HAVE A GOOD HANDLE ON THE EVOLUTION OF THE POTENTIAL COASTAL STORM THAT WOULD DEVELOP UNDER THE RIDGE. IT STILL APPEARS THAT MOST MODELS KEEP THE SIGNIFICANT RAINS OFFSHORE ASSOCIATED WITH THE SYSTEM EXCLUSIVELY. HPC CONTINUED TO FAVOR A BLEND OF THE TWO CAMPS OF MODELS TO ENSURE CONTINUITY OF CURRENT FORECASTS. THIS IS ACCEPTED AS THE BEST STARTING POINT FOR OUR LATE WEEK FORECAST. OUR CHANCE OF RAIN MAY END UP MOSTLY COMING FROM A SCATTERING OF MAINLY DIURNAL SHOWERS AND THUNDERSTORMS THAT MAY FOCUS ALONG OR NEAR THE EXPECTED BACKDOOR FRONT THURSDAY AND THEN WHAT IS LEFT OF THE BOUNDARY FRIDAY. IN ADDITION... SOME MOISTURE MAY EVENTUALLY COME INTO PLAY FROM THE LOW PRESSURE - BUT THE DETAILS CONTINUE SKETCHY AT BEST. UNTIL THAT PROCESS IMPROVES... WE WILL CONTINUE TO FORECAST ABOVE NORMAL TEMPERATURES ESPECIALLY AT NIGHT AS THE DEW POINTS SHOULD BECOME 60+ BY FRIDAY AND LINGER INTO THE WEEKEND. SENSIBLE WEATHER FOR NOW WILL BE PARTLY SUNNY TO MOSTLY CLOUDY EACH DAY. A CHANCE OF MAINLY AFTERNOON AND EARLY NIGHTTIME SHOWERS AND THUNDERSTORMS. LOWS 60-65. HIGHS 78-85. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 140 AM TUESDAY... HIGH CONFIDENCE OF VFR CONDITIONS PERSISTING THROUGH THE CURRENT TAF PERIOD AS BERMUDA HIGH PRESSURE CONTINUES TO RIDGE WESTWARD INTO THE REGION. DIURNAL CU WILL LIKELY DEVELOP ONCE AGAIN ON TUESDAY DURING THE AFTERNOON HOURS WITH SOUTHERLY WINDS BETWEEN 5 TO 8KT. OUTLOOK...VFR CONDITIONS ARE EXPECTED THROUGH AT LEAST WEDNESDAY AS BERMUDA HIGH IN PLACE GRADUALLY WEAKENS...ALLOWING A BACK-DOOR COLD FRONT TO SLIP SOUTH INTO THE AREA LATE WEDNESDAY NIGHT/EARLY THURSDAY. MOISTURE IS LIMITED ALONG THE FRONT AND THUS RAIN CHANCES WILL BE SMALL WITH LITTLE AVIATION IMPACTS. MODELS CONTINUE TO SHOW THE DEVELOPMENT OF AN AREA OF LOW PRESSURE AREA NORTH OF THE BAHAMAS WEDNESDAY/THURSDAY TIME FRAME. MODEL SPREAD REMAINS HIGH WITH THE EVENTUAL EVOLUTION TRACK OF THIS SYSTEM AS IT ENTERS A REGION OF WEAK FLOW OFF THE SE COAST WHERE IT COULD MEANDER FOR SEVERAL DAYS. THIS SYSTEM COULD RESULT IN SOME ADVERSE AVIATION IMPACTS LATE IN THE WORK WEEK AND INTO THE WEEKEND...ESPECIALLY ACROSS COASTAL SECTIONS OF NORTH CAROLINA. ADDITIONALLY...ENHANCED EASTERLY ONSHORE FLOW FROM THIS SYSTEM COULD BRING AN INCREASE THREAT FOR MORNING STRATUS/FOG. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RAH NEAR TERM...RAH SHORT TERM...22 LONG TERM...BADGETT AVIATION...CBL

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