Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 300644 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 245 AM EDT TUE SEP 30 2014 .SYNOPSIS...WEAK LOW PRESSURE OVER NORTHEAST FLORIDA WILL TRACK NORTHEASTWARD OFF THE SOUTHEAST COAST TODAY. WEAK HIGH PRESSURE WILL BUILD OVER THE AREA FROM THE NORTH WEDNESDAY THROUGH THURSDAY. A STRONG STORM SYSTEM WILL APPROACH FROM THE WEST ON FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 222 AM TUESDAY... TODAY... FIRST CONCERN EARLY THIS MORNING IS THE DEGREE OF FOG DEVELOPMENT OVER THE AREA THUS FAR. THE MID LEVEL SHORTWAVE TROUGH IS NOW HEADING EAST OFF THE CAROLINA COAST... WITH THE VEIL OF MID/HIGH CLOUDS DEPARTING ALONG WITH IT. THE DAMP GROUND COMBINED WITH THE CLEARING SKIES AND LIGHT/CALM WINDS SHOULD CONTINUE TO FOSTER DEVELOPMENT OF LOW CLOUDS AND FOG EARLY THIS MORNING... ALTHOUGH THE CURRENT PATCHY/FLEETING NATURE OF THESE CONDITIONS (SEVERAL SITES HAVE BOUNCED AROUND BETWEEN 1/4 MI AND 5 MI IN FOG THE LAST FEW HRS) GIVES US PAUSE AS TO THE NEED FOR A DENSE FOG ADVISORY. THE HRRR DEPICTS A FAIRLY SOLID DECK OF LOW CLOUDS/FOG FORMING OVER THE NEXT FEW HOURS HOWEVER. WILL CONTINUE TO MONITOR THE OBSERVED TRENDS. IF VSBYS DO DROP AND HOLD THERE FOR OVER AN HOUR... THEY`RE LIKELY TO HOLD FIRM THROUGH MID MORNING... GIVEN THE WEAK WIND FIELD THROUGH THE LOWEST FEW THOUSAND FEET RESULTING IN MINIMAL STIRRING/DISPERSION HORIZONTALLY OR VERTICALLY. WILL KEEP SKIES PARTLY TO MOSTLY CLOUDY THROUGH MID MORNING TO ACCOUNT FOR THIS. THEN... ONCE HEATING AND SUBSEQUENT MIXING HELPS TO DISPERSE THE FOG/STRATUS... EXPECT A GOOD BIT OF SUNSHINE THROUGH THE DAY... WITH FLAT AFTERNOON STRATOCU LIKELY TO STAY SCATTERED AT WORST. WITH THICKNESSES CLOSE TO SEASONAL NORMALS... STILL LOOK FOR HIGHS WITHIN A FEW DEGREES OF 80. FOR TONIGHT: THE SURFACE LOW TRACKING TOWARD THE NE WELL OFF THE SE COAST WILL BE FAR ENOUGH TO OUR SE TO MINIMIZE ANY IMPACT ON CENTRAL NC. THE WEAK LOW LEVEL FLOW PATTERN HOLDS WITH A WEAK HIGH PRESSURE RIDGE SPANNING THE AREA AND A VERY WEAK SURFACE LOW/INVERTED TROUGH OVER PA/WV/VA... A REFLECTION OF THE CLIPPER MID LEVEL VORTEX NOW OVER ERN MI THAT IS EXPECTED TO CROSS THE MIDATLANTIC REGION REGION LATE TONIGHT THROUGH WED MORNING. MODELS VARY IN THEIR IMPACTS ON OUR WEATHER WITH THIS FEATURE... WITH THE NAM MUCH MORE BULLISH THAN THE GFS IN TAKING A SLUG OF 850-700 MB MOISTURE EAST ACROSS THE AREA TONIGHT. THIS SEEMS A BIT OVERDONE BUT IT IS SOMEWHAT SUPPORTED BY OBSERVED SOUNDINGS UPSTREAM... SO WILL RETAIN A FEW CLOUDS OVER THE AREA OVERNIGHT... AND LATER FORECASTS CAN INCREASE THIS COVERAGE IF LATER GUIDANCE SUPPORTS THE NAM. LOWS 57-60. -GIH && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
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AS OF 245 AM TUESDAY... AS NOTED ABOVE... WE SHOULD SEE AT LEAST SOME SCATTERED CLOUDS MAINLY OVER THE EAST WED MORNING. THE PRESENCE OR LACK OF SUCH CLOUDS WILL IMPACT HOW MUCH FOG FORMS WED MORNING. WE SHOULD SEE AT LEAST SOME LIGHT FOG TO START THE DAY... AND PERHAPS MORE DENSE IF THE AFOREMENTIONED CLIPPER-ASSOCIATED CLOUDS DO NOT HAPPEN. OTHERWISE... EXPECT A PARTLY TO MOSTLY SUNNY DAY. THE CLIPPER LOW WILL CROSS NEW ENGLAND AS THE STRONG VORTICITY MAX ROUNDS ITS BASE... SHIFTING OFF THE NJ COAST... AND WE SHOULD SEE A BIT MORE FLAT DAYTIME CUMULUS FROM THE TRIANGLE NORTH AND EAST CLOSER TO THE LOW. MODELS SHOW WEAK MID LEVEL RIDGING PUSHING IN FROM THE WEST LATE... BETWEEN THE DEPARTING CLIPPER AND A DEEPENING TROUGH COVERING THE EASTERN ROCKIES AND HIGH PLAINS LATE WED/WED NIGHT. WHILE MODELS SHOW A MINOR PERTURBATION TRACKING EASTWARD OVER THE SOUTHEAST STATES WED NIGHT... THIS SHOULD BE OF LITTLE CONSEQUENCE WITH DEEP DRY AIR MOVING IN. EXPECT DRY WEATHER THROUGH WED NIGHT. THICKNESSES ARE EXPECTED TO START WED ABOUT 10 M ABOVE NORMAL... SUPPORTING HIGHS ABOUT A CATEGORY ABOVE NORMAL... 80-84. SOME CLOUDINESS POSSIBLE WED NIGHT ESPECIALLY OVER THE WEST WHERE MODELS INDICATE AN UPTICK IN LOW LEVEL MOISTURE TRANSPORT GENERATED BY LIGHT BUT CONFLUENT AND UPSLOPE-DIRECTED LOW LEVEL FLOW. LOWS WITHIN A COUPLE DEGREES OF 60. -GIH
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&& .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 120 PM MONDAY... FAIR WEATHER IS EXPECTED THURSDAY AS SFC HIGH PRESSURE...ALONG WITH SHORT WAVE RIDGING ALOFT...SET UP OVER THE AREA. FORECAST SOUNDINGS ARE FAIRLY DRY...ALTHOUGH SUGGEST SOME AFTERNOON SHALLOW CU BENEATH THE MID-LEVEL INVERSION. LOW LEVEL THICKNESS AROUND 1395 SUGGESTS HIGHS A FEW DEGREES ABOVE NORMAL... HIGHS AROUND 80 AND LOWS AROUND 60. THE NEXT WEATHER-MAKER FOR US WILL BE A COLD FRONT THAT`S NOW PROGGED TO SWEEP ACROSS THE STATE LATE ON FRIDAY. FORECAST SOUNDINGS SHOW THE HIGH CLOUDS THICKENING AHEAD OF IT THURSDAY NIGHT...THEN RAPID MID AND LOW LEVEL MOISTURE INCREASE DURING THE AFTERNOON FRIDAY AS SW FLOW IN THE BL INCREASES AHEAD OF THE FRONT. THE END RESULT NOWS LOOKS LIKE A BAND OF SHOWERS JUST AHEAD OF THE FRONT WILL QUICKLY MOVE ACROSS CENTRAL NC PERHAPS DURING THE LATE AFTERNOON AND EVENING HOURS FRIDAY. AS FOR INTENSITY...MOST OF THE PRECIP SHOULD BE OF SHOWER VARIETY...BUT FORECAST SOUNDINGS DO SHOW SOME SKINNY CAPE AND THE POTENTIAL FOR AN ISOLATED THUNDERSTORM... BUT MORE NOTABLY 30-40 KTS OF BULK SHEAR...SO WILL NEED TO KEEP AN EYE ON INSTABILITY TRENDS WITH FUTURE MODELS RUNS. OF COURSE THE TIMING OF THIS WILL BE FINE-TUNED AS WE GET A LITTLE CLOSER...SO IF YOU HAVE OUTDOOR EVENTS FRIDAY AFTERNOON AND/OR EVENING...YOU`LL DEFINITELY WANT TO CHECK BACK LATER THIS WEEK FOR AN UPDATE. NOW LOOKS LIKE THE FRONT WILL BE WELL OFF THE COAST BY SATURDAY MORNING...WITH A COOLING AND DRYING TREND IN ITS WAKE FOR THIS WEEKEND. A LITTLE BREEZY ON SATURDAY IN THE TIGHT PRES GRADIENT AS THE HIGH`S BUILDING IN...BUT OVERALL SHOULD SEE DECENT AMOUNT OF SUNSHINE BOTH DAYS. TEMPS WILL FALL BACK CLOSER TO - OR PERHAPS A LITTLE BELOW- NORMAL BEHIND THE FRONT...HIGHS IN THE MID 70S AND LOWS IN THE MID 50S. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 1240 AM TUESDAY... ADVERSE AVIATION CONDITIONS ARE LIKELY TO HOLD OVER CENTRAL NC THROUGH 14Z OR 15Z THIS MORNING... WITH IMPROVEMENT TO VFR TO FOLLOW BY LATE MORNING... WHICH WILL HOLD THROUGH THE END OF THE TAF VALID PERIOD (06Z WED). THE MID LEVEL TROUGH AXIS OVER THE ERN CAROLINAS WILL CONTINUE TO SHIFT EAST AND OFFSHORE THIS MORNING... TAKING WITH IT THE MID/HIGH CLOUDS AS WELL AS ANY THREAT OF ADDITIONAL PATCHY LIGHT RAIN. THE CLEARING CLOUDS HOWEVER WILL FOSTER FURTHER DEVELOPMENT OF LOW STRATUS/FOG THIS MORNING. THESE IFR/LIFR CONDITIONS HOWEVER WILL BE FLEETING... WITH LOW CLOUDS/FOG NOT A SOLID DECK BUT IN DISCONTINUOUS PATCHES... MAKING THE TAFS CHALLENGING THIS MORNING. PILOTS SHOULD BE PARTICULARLY ALERT FOR POSSIBLE VFR HOLES WITHIN IFR/LIFR CONDITIONS THROUGH MID MORNING. OTHERWISE... ANY CIGS SHOULD BREAK UP BY 15Z OR 16Z... WITH VFR CONDITIONS THEN PREVAILING THROUGH THE AFTERNOON AND EVENING HOURS. SURFACE WINDS WILL REMAIN LIGHT/VARIABLE (MAINLY FROM THE NORTHWEST) MOSTLY UNDER 5 KTS TODAY/TONIGHT. LOOKING BEYOND 06Z EARLY WED MORNING... VFR CONDITIONS WILL PREVAIL THROUGH FRI... ALTHOUGH SHALLOW IFR GROUND FOG IS AGAIN POSSIBLE AREAWIDE 08Z-13Z EACH MORNING WED THROUGH FRI. A STRONG FRONTAL SYSTEM WILL BRING A GOOD CHANCE OF SUB-VFR CONDITIONS WITHIN WIDESPREAD SHOWERS/STORMS FRI AFTERNOON INTO FRI NIGHT. HIGH PRESSURE WILL THEN BUILD IN YIELDING VFR CONDITIONS SAT. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...NP AVIATION...HARTFIELD

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