Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 110009 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 809 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 710 PM THURSDAY... EARLY UPDATE... THE SEVERE THUNDERSTORM WATCH FOR THE EASTERN CWA HAS BEEN CANCELLED. MUCH OF THE WATCH AREA HAS BEEN OVERTURNED BY CONVECTION....SO THE THREAT OF WIDESPREAD SEVERE STORMS HAS DIMINISHED. THERE IS STILL SUPPORT FOR ADDITIONAL STORMS WITH THE UPPER TROUGH TO THE WEST...ESPECIALLY FOR AREAS WEST OF US HWY 1 WHICH REMAIN SLIGHTLY UNSTABLE. -BLS PREVIOUS DISCUSSION... THROUGH TONIGHT: FOCUS REMAINS ON THE EASTERN HALF OF CENTRAL NC... MAINLY ALONG/EAST OF HIGHWAY 1... FOR NUMEROUS SHOWERS AND STORMS THROUGH THIS EVENING. STORMS THUS FAR HAVE BEEN PRIMARILY MULTICELL CLUSTERS WITH A COUPLE OF PROMINENT SUPERCELLS... AND THIS MODE OF CONVECTION IS LIKELY TO PERSIST FOR SEVERAL MORE HOURS. 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... ALONG AND AHEAD OF A WEAK SURFACE TROUGH. THIS FORCING FOR ASCENT COMBINED WITH WEAK HEIGHT FALLS AND NRN-STREAM ENERGY... ENHANCED LIFT WITHIN THE RIGHT ENTRANCE REGION OF THE 100+ KT UPPER JET CORE CENTERED OVER THE NORTHEAST STATES... AND ABOVE NORMAL PW (1.8-2.0 IN.) WILL ALL SUPPORT A CONTINUED THREAT OF NUMEROUS SHOWERS AND STORMS IN THE EAST... WITH LESSER COVERAGE IN THE WEST WITHIN LOWER PW AND SLIGHTLY MORE STABLE AIR DUE TO THIS MORNING`S SHOWERS/CLOUDS. THIS SCENARIO IS SUPPORTED BY THE LATEST HRRR GUIDANCE AS WELL AS THE WRF-ARW/NMM. CONCERN PERSISTS FOR A FEW SEVERE STORMS INTO EARLY EVENING IN THE EASTERN CWA (PARTICULARLY SOUTHEAST SECTIONS SE OF RALEIGH) WHERE MODERATE INSTABILITY IS ALIGNED WITH DECENT DEEP LAYER EFFECTIVE SHEAR OF 25- 30 KTS... 500 MB WINDS OF 30-40 KTS... AND D-CAPE OF 800-1200 J/KG. AS THE WEAKENING MID LEVEL SHEAR AXIS SHIFTS SLOWLY EASTWARD AND OVERHEAD OVERNIGHT... STORM COVERAGE SHOULD SLOWLY SHRINK AS WE LOSE HEATING... ENDING LAST OVER THE ERN COASTAL PLAIN... AS THE SURFACE BOUNDARY SETTLES OVER SE NC. PLENTIFUL LOW LEVEL MOISTURE AND WEAK MASS CONVERGENCE SHOULD RESULT IN POCKETS OF FOG/STRATUS AREAWIDE OVERNIGHT. HIGH-RES GUIDANCE AND PERSISTENCE SUGGEST LOWS TONIGHT OF 67-73. FOR FRI/FRI NIGHT: AS THE DAMPENING SHEAR AXIS SHIFTS TO OUR SE IN LINE WITH THE DISSIPATING SURFACE TROUGH... THE HIGHER PW VALUES WILL ACCORDINGLY SHIFT TO THE COASTAL PLAIN... LEAVING A LIGHT NNE LOW LEVEL FLOW AND RELATIVELY (FOR JULY) DRY COLUMN OVER THE NRN AND WRN CWA. MODELS GENERALLY INDICATE VERY LITTLE PRECIP COVERAGE... CONFINING AFTERNOON CONVECTION TO THE COASTAL PLAIN AND SE SANDHILLS WHERE MODELS PROJECT MUCAPE PEAKING AT 1000-1500 J/KG. WILL RETAIN CHANCE POPS HERE WITH ISOLATED CHANCES TO THE NW. A DIP IN THICKNESSES TO SLIGHTLY BELOW NORMAL VALUES SUPPORTS HIGHS OF 85-90. EXPECT LITTLE MORE THAN PATCHY SHOWERS FRI NIGHT. LOWS 66-71. -GIH && .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 /00Z FRIDAY THROUGH TUESDAY/... AS OF 806 PM THURSDAY... SHOWERS AND THUNDERSTORMS CONTINUE TO AFFECT KRDU... KFAY... AND KRWI... AND ARE LESS LIKELY AT KINT AND KGSO. WINDS WILL BECOME NORTHERLY TO NORTHEASTERLY OVERNIGHT AS THE FRONT TO THE WEST OF THE AREA SLOWLY MOVES THROUGH. THERE ARE INDICATIONS OF A PERIOD OF STRATUS OR FOG NEAR SUNRISE BETWEEN 09 AND 12Z... AND FOG SEEMS MORE LIKELY AT KRDU... KFAY... AND KRWI... WHERE THE MOST RAIN HAS FALLEN. 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/BLS SHORT TERM...KRD LONG TERM...KRD AVIATION...SEC/HARTFIELD

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