Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 130538 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 138 AM EDT SUN JUL 13 2014 .SYNOPSIS...A HIGHLY ANOMALOUS UPPER LEVEL TROUGH WILL DIG SOUTHEAST FROM CANADA INTO THE EASTERN UNITED STATES EARLY THIS WEEK AND PERSIST THROUGH MID TO LATE WEEK. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 130 AM SUNDAY... A RELATIVELY DRY/SUBSIDENT AIRMASS WILL PERSIST OVER THE REGION TODAY...ON THE EASTERN PERIPHERY OF AN UPPER LEVEL RIDGE EXTENDING EAST FROM THE CENTRAL PLAINS INTO THE SOUTHEAST STATES. A DEEP /HIGHLY ANOMALOUS/ UPPER LEVEL LOW DIGGING SOUTHEAST FROM CENTRAL CANADA INTO THE UPPER GREAT LAKES WILL RESULT IN STRENGTHENING CYCLONIC FLOW ALOFT ACROSS THE OH VALLEY AND MID-ATLANTIC THIS AFTERNOON INTO TONIGHT. GIVEN THAT THE BEST FORCING WILL REMAIN WELL N/NW AND THAT DIURNAL DESTABILIZATION WILL BE MARGINAL (AT BEST)... EXPECT DRY CONDITIONS TO PREVAIL IN MOST AREAS THROUGH TONIGHT. WILL CONTINUE TO INDICATE A SLIGHT CHANCE OF CONVECTION IN THE FAR NW PIEDMONT WHERE INCREASINGLY NW FLOW ALOFT WOULD ALLOW UPSTREAM CONVECTION TO PROPAGATE INTO THE N/NW PIEDMONT FROM THE MOUNTAINS. OTHERWISE...EXPECT CONDITIONS SIMILAR TO YESTERDAY ALBEIT SLIGHTLY WARMER WITH HIGHS IN THE LOWER 90S. LOWS TONIGHT ALSO A FEW DEGREES WARMER...IN THE LOWER 70S. -VINCENT && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 130 AM SUNDAY... EXPECT AT OR ABOVE NORMAL CHANCES FOR CONVECTION MONDAY AFT/EVE INTO MON NIGHT AS CYCLONIC FLOW ALOFT STRENGTHENS OVER THE REGION IN THE PRESENCE OF AN INCREASINGLY MOIST/UNSTABLE AIRMASS...ESPECIALLY IN THE N/NW PIEDMONT IN CLOSER VICINITY TO SMALL AMPLITUDE WAVES EMBEDDED IN STRONGER FLOW ALOFT OVER THE OH VALLEY AND MID ATLANTIC. EXPECT HIGHS SIMILAR TO PREVIOUS DAYS...THOUGH PERHAPS SEVERAL DEGREES COOLER IF CONVECTION /OUTFLOW/ IS PRESENT PRIOR TO PEAK HEATING. -VINCENT && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 245 PM SATURDAY... A DEEP VORTEX IS PROGGED TO MOVE SOUTH OUT OF CANADA AND TRACK ACROSS THE GREAT LAKES MONDAY INTO TUESDAY BEFORE HEADING NORTHEAST INTO QUEBEC BY THE MIDDLE OF THE WEEK. THIS WILL RESULT IN AN ANOMALOUSLY DEEP TROUGH DEVELOPING OVER THE EASTERN HALF OF THE CONUS. AS A RESULT...PRECIP CHANCES WILL BE ON THE INCREASE FOR NEXT WEEK...ESPECIALLY LATE MONDAY NIGHT INTO EARLY WEDNESDAY MORNING AS A FRONT APPROACHES THE AREA (THIS IS SLIGHTLY FASTER THAN PREVIOUS RUNS). ALSO...GIVEN THIS UNSEASONABLY STRONG TROUGH...THE MID LEVEL FLOW IS EXPECTED TO STRENGTHEN (ALTHOUGH THE REGION WILL BE ON THE SOUTHERN FRINGES OF THE BEST UPPER DYNAMICS). THERE ARE STILL SOME TIMING ISSUES AMONG THE MODELS (FRONT COMING THROUGH DURING PEAK HEATING OR NOT)...NEVERTHELESS THE POSSIBILITY OF AN ORGANIZED SEVERE THREAT WILL EXIST AND THIS WILL CONTINUED TO BE MONITORED AS MODELS COME INTO BETTER AGREEMENT. MODELS CONTINUE TO FLIP FLOP WITH REGARDS TO IF THIS FRONT WILL PUSH ALL THE WAY THROUGH THE AREA OR NOT...BUT FOR NOW IT LOOKS LIKE THE FRONT WILL STALL SOMEWHERE ACROSS EASTERN CAROLINA. HOWEVER... LATEST MODEL RUNS SHOW MORE IN THE WAY OF DRIER/COOLER AIR FILTERING INTO THE FORECAST AREA AS THE FRONT PUSHES FURTHER AWAY FROM THE AREA (ESPECIALLY ACROSS THE NORTHWESTERN HALF OF THE FORECAST AREA). THUS...WILL SHOW A DECREASE IN POPS FOR THE MIDDLE OF THE WEEK...BUT WILL KEEP A CHANCE IN (HIGHEST ACROSS THE EASTERN HALF OF THE FORECAST AREA) GIVEN THE UNCERTAINTY WITH REGARDS TO WHERE THE FRONT ENDS UP. THEN MODELS ARE HINTING AT A WAVE(S) OF LOW PRESSURE DEVELOPING AND TRACKING ALONG THE STALLED FRONT...WHICH WOULD RAISE PRECIP CHANCES ONCE AGAIN FOR THE END OF THE PERIOD. HIGH TEMPS AHEAD OF THE FRONT ARE EXPECTED TO BE IN THE UPPER 80S TO LOW/MID 90S ON MONDAY AND THEN MID/UPPER 80S TO NEAR 90 DEGREES ON TUESDAY GIVEN THE PRECIP CHANCES. THEN SLIGHTLY COOLER TEMPS (MOSTLY LOW/MID 80S) ARE EXPECTED THROUGH FRIDAY GIVEN THE DEEP TROUGHING OVER THE EAST COAST AND THE POSSIBILITY THAT THE FRONT WILL PUSH THROUGH THE AREA. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 130 AM SUNDAY... 24-HR TAF PERIOD: VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD IN MOST LOCATIONS. EXCEPTIONS INCLUDE A POTENTIAL FOR SUB-VFR FOG AT THE FAY/RWI TERMINALS BETWEEN 08-12Z THIS MORNING...AND A POTENTIAL FOR ISOLD CONVECTION AT THE INT/GSO TERMINALS DURING THE LATE AFTERNOON AND EVENING HOURS (20-00Z). CALM OR LIGHT SOUTHERLY WINDS THIS MORNING WILL BECOME SSW/SW AT 5-10 KT DURING THE DAY. LOOKING AHEAD: EXPECT WIDESPREAD SHOWERS AND THUNDERSTORMS MONDAY THROUGH THE END OF THE WORK WEEK IN ASSOCIATION WITH A HIGHLY ANOMALOUS UPPER LEVEL TROUGH OVER THE EASTERN CONUS. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...KRD AVIATION..VINCENT

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