Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS62 KRAH 261751 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 150 PM EDT TUE AUG 26 2014 .SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE WILL EXTEND SOUTHWARD INTO THE REGION THROUGH WEDNESDAY. A WEAK BACK DOOR FRONT WILL APPROACH FROM THE NORTH LATE THURSDAY.
-- End Changed Discussion --
&& .NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
AS OF 1030 AM TUESDAY... THE WEATHER OVER CENTRAL NC CONTINUES TO BE DOMINATED BY HIGH PRESSURE. THE 12Z UPPER AIR ANALYSES SHOW HIGH PRESSURE TO THE WEST...APPROX OVER MO/IL. AT THE SURFACE...HIGH PRESSURE CONTINUES TO RIDGE INTO THE AREA FROM THE NORTH-NORTHEAST...RESULTING IN NORTHEASTERLY SURFACE FLOW...WHICH IN TURN YIELDS COMFORTABLE TEMPERATURES AND RELATIVELY LOW HUMIDITIES. HURRICANE CRISTOBAL WAS LOCATED JUST EAST OF THE BAHAMAS AT 12Z TODAY...AND WILL CONTINUE TO MOVE NORTH AND SLIGHTLY NORTHWEST ALONG BUT WELL OFF THE SE ATLANTIC COAST THROUGH TONIGHT. THE BIGGEST IMPACT IN CENTRAL NC WILL BE CONTINUED NORTH-NORTHEASTERLY WINDS...THE STRONGEST OF WHICH WILL BE ALONG THE COAST AND WELL OFFSHORE. EXPECT MAINLY SCATTERED LOW TO MID CLOUDS TODAY WITH HIGHS IN THE MID 80S. THE MID TO UPPER LEVELS WILL REMAIN DRY THROUGH TONIGHT...HOWEVER SOME MOISTURE TRAPPED IN THE LOW LEVELS OVERNIGHT COULD YIELD SOME OVERCAST SKIES IN THE EAST. WITH THE CONTINUED NE FLOW AND DEWPOINTS IN THE UPPER 50S TO AROUND 60 DEGREES...EXPECT LOWS GENERALLY IN THE SAME RANGE...UPPER 50S TO LOW 60S. -KC
-- End Changed Discussion --
&& .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
AS OF 150 PM TUESDAY... WEDNESDAY (AS OF 250 AM): HURRICANE CRISTOBAL IS EXPECTED TO LIFT NORTHWARD AND PASS AROUND 500 MILES TO THE EAST OF THE NC COAST ON WEDNESDAY. THUS...EXPECT NO IMPACT FROM THE PASSING TROPICAL SYSTEM FOR CENTRAL NC...EXCEPT A POSSIBLE ENHANCED OF THE TEMPS ON THE WARM SIDE OVER OUR AREA. AFTERNOON LOW LEVEL THICKNESS VALUES ARE EXPECTED TO INCREASE SOME 15 TO 25 METERS ON WEDNESDAY...VS TODAY. THUS...HAVE RAISED HIGH TEMPS ON WEDNESDAY TO AROUND 90/LOWER 90S...AND WE COULD EVEN SEE A FEW MID 90S. OTHERWISE DRY WEATHER IS EXPECTED AS VERY STABLE CONDITIONS PERSIST OVER THE AREA. -BSD FOR THU/THU NIGHT: STILL APPEARS LIKELY THAT THE BACKDOOR SURFACE FRONT WILL PUSH INTO FAR NE NC THU AFTERNOON... THEN CONTINUE DROPPING SLOWLY TO THE SSW... TO BE SITUATED FROM NW NC TO THE SRN OUTER BANKS BY LATE THU NIGHT. PRECISELY HOW FAR SSW THE FRONT GETS WILL DEPEND ON THE DENSITY OF THE PARENT HIGH NOSING DOWN FROM NY/PA. LOW LEVEL MASS CONVERGENCE ALONG THIS FRONT IS LIKELY TO BE THE PRIMARY FORCING MECHANISM... GIVEN THAT ANY DPVA WITHIN THE FAIRLY WEAK NW FLOW ALOFT WILL BE MINOR. THE GFS SHOWS A THIN STRIP OF MUCAPE UNDER 750 J/KG ACROSS THE FAR NORTHERN CWA LATE THU/THU NIGHT... ALTHOUGH THE NAM IS MORE UNSTABLE (1000-1500 J/KG) WITH A BIT MORE PROGRESSIVE (MORE TO THE SW) FRONT ACROSS CENTRAL NC. THE GFS HAS BETTER RUN-TO-RUN CONTINUITY ALONG WITH SUPPORT FROM THE ECMWF... AND ITS LOWER CAPE MAKES SENSE GIVEN THAT ITS DEW POINTS ARE 5-8 DEGREES COOLER AND MORE REASONABLE. DEEP LAYER SHEAR WILL REMAIN WEAK... WITH HIGHEST VALUES NEAR 25 KTS ONLY OVER THE NE CWA. WILL HOLD CLOSE TO EXISTING FORECAST CONVECTION CHANCES... WITH EXPECTATIONS OF AFTERNOON STORMS FORMING OVER THE NRN MOUNTAINS DRIFTING TO THE ESE ACROSS THE NRN CWA DURING THE LATE AFTERNOON AND EVENING BEFORE DIMINISHING GRADUALLY AND EXITING OVERNIGHT. COULD SEE SMALL LINGERING CAPE OVERNIGHT AS SURFACE DEW POINTS RECOVER. GIVEN THE LACK OF LOW LEVEL MOISTURE TRANSPORT AND SLOWLY RISING HEIGHTS ALOFT... HOLDING CONVECTIVE COVERAGE AS ISOLATED STILL LOOKS GOOD. MODELS KEEP TRENDING WARMER... GIVING THICKNESSES 10-15 M ABOVE NORMAL AND WARMING STATISTICAL GUIDANCE WITH EACH RUN... SUPPORTING ABOVE-NORMAL HIGHS OF 89-93 AND LOWS 67-70. -GIH
-- End Changed Discussion --
&& .LONG TERM /FRIDAY THROUGH TUESDAY/...
-- Changed Discussion --
AS OF 150 PM TUESDAY... FOR FRI/FRI NIGHT: THE WEAK SURFACE FRONT SHOULD BE STALLED ACROSS NC FROM NW TO THE CENTRAL COAST EARLY FRI... THEN START TO DISSOLVE WITH LOW LEVEL FLOW BECOMING SOUTHEASTERLY AS THE PROGRESSIVE PARENT HIGH TO THE NNE SHIFTS SWIFTLY OFF THE NORTHEAST COAST. WEAK LOW LEVEL CONFLUENT FLOW AND IMPROVED MOISTURE POOLING ALONG THE DYING FRONT MAY FUEL ANOTHER ROUND OF ISOLATED STORMS ACROSS THE NRN CWA... ALTHOUGH HEIGHTS WILL BE RISING ALOFT WITH THE DEPARTURE OF THE MID LEVEL TROUGH OFF THE CANADIAN MARITIMES... ALLOWING RIDGING TO BUILD OVER THE SOUTHEAST STATES... AND THIS WARMING AND STABILIZATION ALOFT SHOULD LIMIT COVERAGE. LITTLE CHANGE IN AIR MASS WITH THICKNESSES INCHING UPWARD... AND HIGHS SHOULD AGAIN BE WITHIN A FEW DEGREES OF 90 WITH LOWS IN THE UPPER 60S/AROUND 70. FOR SAT-TUE: THE DRY WEATHER EARLY IN THIS PERIOD WILL GRADUALLY GIVE WAY TO INCREASED STORM CHANCES HEADING INTO EARLY NEXT WEEK. THE MID LEVEL LOW NOW OVER NV WILL CONTINUE HEADING EASTWARD THEN NORTHEAST... DAMPENING AS IT GETS DRAWN UP BY PROGRESSIVE LONGWAVE TROUGHING OVER SRN CANADA. STRONG RIDGING WILL PERSIST ALONG THE SOUTHEAST COAST SAT... AND WITH THE SE/S LOW LEVEL FLOW REMAINING LIGHT... MOISTURE FLUX WILL BE SUBDUED. THE GFS DEPICTS MUCAPE VALUES RISING TO 1000-1500 J/KG SAT... BUT THE SMALL DEEP LAYER SHEAR UNDER 20 KTS WILL LIMIT STORM ORGANIZATION/STRENGTH. AND THERE MAY NOT BE ANY DISCERNIBLE BOUNDARY LEFT OVER CENTRAL NC TO FOCUS CONVECTION. GFS/ECMWF ARE BOTH FAIRLY DRY... SO WILL KEEP POPS SAT UNDER CLIMATOLOGY AT LESS THAN 15%. THE DAMPENED WAVE MOVES THROUGH THE ST LAWRENCE VALLEY SUN/SUN NIGHT... AND WHILE THIS MAY HELP TAMP DOWN THE RIDGE A BIT... THE ENSUING SW FLOW ALOFT REMAINS VERY LIGHT. SURFACE LEE TROUGHING IS EXPECTED TO FORM OVER CENTRAL NC... AND WITH IMPROVED LOW LEVEL MOISTENING AND RISING MLCAPE PREDICTIONS TO 1500-2000 J/KG OVER MUCH OF CENTRAL NC... WE SHOULD SEE A SMALL UPTICK IN CONVECTION CHANCES SUN/SUN NIGHT. OPERATIONAL MODEL DETAILS DIVERGE AFTER THIS TIME BUT IT APPEARS THAT HEIGHTS WILL BE ON THE SLOW RISE AGAIN MON/TUE... ALBEIT WITH A WEAK SHEAR AXIS POSSIBLY LAYING BACK THROUGH THE WRN PIEDMONT. THIS IS LIKELY TO LEAD TO A TREND BACK TOWARD CLIMATOLOGICALLY NORMAL POPS... SCATTERED MAINLY DURING THE AFTERNOON/EVENING... AND WILL RETAIN CHANCE POPS MON EXTENDING THROUGH TUE. THICKNESSES ARE PROJECTED TO HOLD ABOVE NORMAL BY AROUND 10 M... SO WILL STAY WITH HIGHS IN THE UPPER 80S TO AROUND 90 WITH LOWS IN THE UPPER 60S TO AROUND 70. -GIH
-- End Changed Discussion --
&& .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 130 PM TUESDAY... 24-HOUR TAF PERIOD: HIGH PRESSURE REMAINS IN PLACE...RESULTING IN DRY NE FLOW ACROSS THE AREA. WITH THE EXCEPTION OF SOME LINGERING CIGS AROUND 3 KFT...VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD. THE CURRENT SCATTERED TO BROKEN CIGS SHOULD GRADUALLY DECREASE IN COVERAGE AND LIFT TO AROUND 3.5-4 KFT THIS AFT/EVE. WINDS WILL BE BREEZY AT 8-12 KTS...WITH THE POTENTIAL FOR SOME INTERMITTENT GUSTS TO AROUND 15 KTS THROUGH SUNSET...BECOMING LIGHT AND VARIABLE THEREAFTER. THE MODELS SUGGEST SOME MOISTURE TRAPPED IN THE LOW LEVELS OVERNIGHT OVER EASTERN PORTIONS OF THE AREA (KRDU AND KRWI)...COMBINED WITH LIGHT WINDS AND GOOD RADIATIONAL COOLING... CANNOT COMPLETELY RULE OUT A BRIEF PERIOD OF SOME SUB-VFR VISBYS TOWARDS DAYBREAK WEDNESDAY...HOWEVER CONFIDENCE REMAINS LOW AT THIS TIME SO WILL NOT INCLUDE MENTION IN THIS ISSUANCE. LOOKING AHEAD: VFR CONDITIONS WILL PREVAIL THROUGH MID-WEEK AS DRY HIGH PRESSURE PERSISTS OVER THE CAROLINAS. A SMALL CHANCE FOR ISOLATED CONVECTION ACROSS THE NORTH WILL RETURN THU/FRI AS DISTURBANCES TRAVERSE ALONG A WEAK BACKDOOR FRONT AS DRIFTS SOUTH TOWARD THE REGION...THOUGH VFR CONDITIONS SHOULD STILL PREVAIL AT MOST (IF NOT ALL) TERMINALS. CHANCES FOR SUB-VFR CONDITIONS DURING THE PRE-DAWN HOURS WILL INCREASE THIS WEEKEND AS LOW LEVEL MOISTURE INCREASES UNDER SW FLOW. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...KC SHORT TERM...BSD/HARTFIELD LONG TERM...HARTFIELD AVIATION...KC

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.