Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 101915 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 315 PM EDT THU JUL 10 2014 .SYNOPSIS...A WEAKENING COLD FRONT WILL SHIFT THROUGH THE REGION THROUGH TONIGHT... THEN MOVE TOWARD THE COAST FRIDAY. WEAK HIGH PRESSURE WILL SETTLE OVER THE REGION SATURDAY INTO SUNDAY. && .NEAR TERM /THROUGH FRIDAY NIGHT/... AS OF 1000 AM THURSDAY... REST OF TODAY: STILL LOOKS QUITE WET FOR MOST... ESPECIALLY ALONG/EAST OF HIGHWAY 1 THIS AFTERNOON/EVENING. CONFLUENT SSW FLOW ALOFT AHEAD OF A MID LEVEL SHEAR AXIS SITTING JUST TO OUR WEST WILL CONTINUE TO DRAW POCKETS OF SRN STREAM VORTICITY ACROSS NC... AND THESE COMBINED WITH WEAK HEIGHT FALLS AND NRN-STREAM-ROOTED ENERGY HAVE TRIGGERED SCATTERED SHOWERS OVER MUCH OF THE PIEDMONT THIS MORNING. WE`RE ALSO SEEING ENHANCED FORCING FOR ASCENT WITHIN THE RIGHT ENTRANCE REGION OF THE 100+ KT UPPER JET CORE CENTERED OVER THE NORTHEAST STATES. THIS WILL HOLD OVER THE REGION TODAY... AS A WEAK 850 MB TROUGH EASES OVERHEAD FROM THE WEST... WITHIN A MOIST COLUMN (PW VALUES OVER 1.6 INCHES AND PROJECTED TO RISE FURTHER). EXPECT CONVECTIVE GROWTH TO BE FOCUSED OVER CENTRAL/ERN CWA NEAR DIFFERENTIAL HEATING AND OTHER SUBTLE BOUNDARIES... WITH THE BEST COVERAGE (NUMEROUS TO CATEGORICAL) ALONG/EAST OF HIGHWAY 1. BASED ON MODEST CONTRIBUTION TO LIFT BY DYNAMIC FEATURES (INCLUDING IMPRESSIVE-FOR-JULY CYCLONIC WINDS OF 30-40 KTS AT 500 MB) AND EXPECTED MODERATE INSTABILITY (GFS MUCAPE OF 1000-2000 J/KG)... AN ISOLATED STORM OR TWO COULD BECOME STRONG WITH DAMAGING WIND GUSTS AS THE MAIN THREAT... ALONG WITH HEAVY DOWNPOURS AND TRAINING ECHOES. (FORECAST CAPE AT -10C TO -30C IS MARGINAL GIVEN THE SOMEWHAT MILD MID LEVELS... BUT A FEW HAIL OCCURRENCES ARE ALSO POSSIBLE TODAY.) EXPECT GENERALLY MOSTLY CLOUDY SKIES WITH HIGHS 85- 91... AS THE MORNING CLOUD COVER OVER THE NORTHWEST HELPS TO TEMPER HEATING. -GIH TONIGHT...SCATTERED CONVECTION WILL BE MAINLY CONFINED TO THE COASTAL PLAIN AS THE MID LEVEL SHEAR AXIS DRIFTS SLOWLY E-SE. MIN TEMPS UPPER 60S NW TO LOWER 70S SE. -WSS MID LEVEL SHEAR AXIS AND ATTENDANT SFC BOUNDARY MAINTAINS A POSITION IN VICINITY OF THE COASTAL PLAIN FRIDAY. WITH AIR MASS STILL MOIST AND SLIGHT-MODERATELY UNSTABLE...EXPECT ANOTHER ROUND OF SCATTERED SHOWERS/THUNDERSTORMS WITH LOCALLY HEAVY RAIN TO OCCUR. SIMILAR TO TODAY...EXPECT GREATEST COVERAGE TO OCCUR EAST OF HIGHWAY 1. FARTHER NW...A SLIGHTLY DRIER MORE STABLE AIR MASS AND WEAK DOWNSLOPE FLOW IN THE WAKE OF THE MID LEVEL SHEAR AXIS WILL INHIBIT CONVECTIVE DEVELOPMENT. STILL...WITH HEATING EXPECT ISOLATED-SCATTERED CONVECTION DURING THE HEAT OF THE AFTERNOON. MAX TEMPS FAIRLY UNIFORM DUE TO CLOUDS/CONVECTION. MAX TEMPS 85-88. FRIDAY NIGHT...BULK OF CONVECTION WILL DIMINISH WITH LOSS OF HEATING THOUGH COULD SEE A FEW SHOWERS PERSIST PAST MIDNIGHT ALONG OUR EASTERN PERIPHERY DUE TO PRESENCE OF MID LEVEL SHEAR AXIS. MIN TEMPS UPPER 60S TO AROUND 70. -WSS && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 315 PM THURSDAY... THE MID LEVEL TROUGH AXIS (CURRENTLY MOVING TOWARDS THE AREA) WILL PUSH OFFSHORE ON SATURDAY...WHILE THE MID LEVEL RIDGE TRIES TO BUILD EASTWARD TOWARDS THE REGION. MODELS HAVE TRENDED DRIER FOR THE WEEKEND...ESPECIALLY ON SATURDAY GIVEN THE DRIER AIR FILTERING INTO THE REGION BEHIND THE DEPARTING TROUGH. IN FACT...FORECAST SOUNDINGS INDICATE VERY LIMITED DEEP LAYER MOISTURE...WITH PWAT VALUES PROGGED TO RANGE BETWEEN 1-1.25 INCHES (WELL BELOW NORMAL). THEREFORE... WILL GO WITH A MOSTLY DRY FORECAST FOR SATURDAY. MOISTURE WILL START TO RECOVER SOME ON SUNDAY AND A SURFACE TROUGH WILL SHARPEN UP OVER THE REGION...LEADING TO A BETTER CHANCE OF MOSTLY DIURNAL TYPE STORMS...ALTHOUGH OVERALL COVERAGE SHOULD STILL BE RATHER LOW. LOW LEVEL THICKNESS VALUES ARE PROGGED TO BE NEAR 1420M ON SATURDAY AND GIVEN EXPECTED LACK OF PRECIP...TEMPS SHOULD RISE INTO THE UPPER 80S TO LOWER 90S. BY SUNDAY...LOW LEVEL THICKNESS VALUES ARE EXPECTED TO CLIMB ANOTHER 5-10M...RESULTING HIGH TEMPS A FEW DEGREES WARMER...GENERALLY LOW TO MID 90S (ALTHOUGH MORE CLOUDS MAY BE AROUND WHICH WOULD TEMPER THE WARMING SOME). && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 315 PM THURSDAY... A DEEP VORTEX IS PROGGED TO MOVE SOUTH OUT OF CANADA AND EVENTUALLY ACROSS THE GREAT LAKES THROUGH THE MIDDLE OF NEXT WEEK. THIS WILL RESULT IN A DEEP TROUGH DEVELOPING OVER THE EASTERN HALF OF THE CONUS. THEREFORE...PRECIP CHANCES WILL BE ON THE INCREASE FOR NEXT WEEK...ESPECIALLY LATE TUESDAY INTO EARLY WEDNESDAY AS A FRONT APPROACHES THE AREA. ALSO...GIVEN THIS UNSEASONABLY STRONG TROUGH... THE MID LEVEL FLOW IS EXPECTED TO STRENGTHEN AND THEREFORE THE POSSIBILITY OF AN ORGANIZED SEVERE THREAT WILL EXIST AND THIS WILL BE MONITORED OVER THE NEXT SEVERAL DAYS. THEN THERE IS STILL A GOOD BIT OF UNCERTAINTY WITH REGARDS TO IF THIS FRONT WILL PUSH ALL THE WAY THROUGH THE AREA...BUT FOR NOW IT LOOKS LIKE THE FRONT WILL STALL SOMEWHERE ACROSS THE CAROLINAS. THUS...WILL SHOW A LITTLE DECREASE IN POPS FOR THE LATTER HALF OF THE WEEK...BUT WILL KEEP A CHANCE IN GIVEN THE UNCERTAINTY WITH REGARDS TO WHERE THE FRONT ENDS UP. HIGH TEMPS AHEAD OF THE FRONT ARE EXPECTED TO BE IN THE LOW TO MID 90S ON MONDAY AND POSSIBLY TUESDAY...ALTHOUGH DEPENDING ON THE TIMING OF THE PRECIP...TEMPS COULD BE SLIGHTLY LOWER ON TUESDAY. THEN SLIGHTLY COOLER TEMPS ARE EXPECTED WEDNESDAY AND THURSDAY GIVEN THE DEEP TROUGHING OVER THE EAST COAST AND THE POSSIBILITY THAT THE FRONT WILL PUSH THROUGH THE AREA. && AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 1250 PM THURSDAY... WHILE A FEW CLOUDS BASED AT 2000-3000 FT AGL PERSIST OVER CENTRAL NC... VFR CONDITIONS ARE EXPECTED TO DOMINATE AT CENTRAL NC TERMINAL SITES THROUGH 04Z THIS EVENING... ALTHOUGH A SHORT PERIOD OF MVFR CIGS AND IFR VSBYS WITH HEAVY RAIN AND STRONG/VARIABLE WIND GUSTS ARE POSSIBLE IN/NEAR SHOWERS/STORMS. STORMS COULD AFFECT TAF SITES AT ANY TIME THROUGH MID EVENING BUT ARE MOST LIKELY TO IMPACT INT/GSO IN THE 18Z-21Z WINDOW... RDU IN THE 20Z-02Z WINDOW... AND FAY/RWI IN THE 21Z-04Z WINDOW. STARTING NEAR 04Z... SHOWERS AND ISOLATED STORMS WITH SUB-VFR CONDITIONS MAY BE ONGOING NEAR RWI/FAY AND PERHAPS RDU... ALTHOUGH COVERAGE SHOULD STEADILY SHRINK OVERNIGHT. WIDESPREAD MVFR TO IFR FOG AND STRATUS ARE EXPECTED TO FORM AFTER 06Z AND PERSIST UNTIL 12Z FRI MORNING... AFTER WHICH TIME AN IMPROVEMENT TO VFR IS EXPECTED THROUGH 14Z. AWAY FROM STORMS... PREVAILING WINDS WILL REMAIN LIGHT... UNDER 10 KTS... MAINLY FROM THE S AND SW (EXCEPT VARIABLE AT INT/GSO). LOOKING BEYOND 18Z FRI... VFR CONDITIONS WILL AGAIN DOMINATE BUT A FEW STORMS WITH GUSTY WINDS AND SUB-VFR CONDITIONS ARE EXPECTED AT RDU AND PARTICULARLY RWI/FAY FRI AFTERNOON/EVENING. ARRIVAL OF A DRIER AND MORE STABLE AIR MASS FRI NIGHT THROUGH SUN WILL LEAD TO A HIGH CONFIDENCE IN VFR CONDITIONS OVER THE WEEKEND. A RETURN TO SCATTERED LATE DAY SHOWERS AND STORMS IS EXPECTED MON-TUE... WITH A CHANCE OF LIGHT SUB-VFR FOG WITHIN A FEW HOURS OF DAWN BOTH MON AND TUE. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS/HARTFIELD NEAR TERM...HARTFIELD/WSS SHORT TERM...KRD LONG TERM...KRD AVIATION...HARTFIELD

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