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 250802 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 400 AM EDT WED MAR 25 2015 .SYNOPSIS...HIGH PRESSURE ALONG THE MID-ATLANTIC COAST WILL PUSH A BACKDOOR COLD FRONT SOUTHWESTWARD THROUGH THE CAROLINAS THIS MORNING. A WARM FRONT WILL APPROACH FROM THE SOUTHEAST THIS AFTERNOON...THEN TEMPORARILY STALL OVER THE REGION TONIGHT. THE WARM FRONT WILL LIFT NORTH OF THE AREA ON THURSDAY...AS A COLD FRONT APPROACHES FROM THE WEST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1025 PM TUESDAY... SURFACE HIGH PRESSURE WILL CONTINUE TO RIDGE INTO CENTRAL NC OVERNIGHT AS IT SLIDES SOUTHWARD ALONG THE MID ATLANTIC COAST. LOW CLOUDS WILL CONTINUE TO MOVE INTO THE NORTHERN PORTIONS OF THE AREA...PARTICULARLY IN THE TRIAD...AND PERSIST THROUGH THE NIGHT. THERE IS STILL A CHANCE FOR SOME DRIZZLE OR LIGHT RAIN OVERNIGHT BUT COVERAGE WILL BE LIMITED. EXPECT LOWS RANGING FROM THE LOW 40S NE TO LOW 50S SW. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 315 PM TUESDAY... IN SITU CAD WEDGE WILL BE IN PLACE FOR MUCH OF THE DAY ON WEDNESDAY AND THIS WILL SET UP A DIFFERENTIAL HEATING GRADIENT WITH HIGHS ONLY TOPPING OUT IN THE UPPER 50S TO LOWER 60S IN THE TRIAD BUT POSSIBLY REACHING THE LOWER 70S IN THE SOUTHEAST. THIS DIFFERENCE IN TEMPERATURE COULD COME IN TO PLAY LATER IN THE DAY IN REGARDS TO DEVELOPING INSTABILITY AS HIGH PRESSURE OFF THE COAST WILL GRADUALLY SLIDE OUT TO SEA...THE WEDGE FRONT WILL BREAK DOWN AND IN ITS PLACE SOUTHERLY RETURN FLOW WITH A LOT OF LOW LEVEL MOISTURE TRANSPORT OFF OF THE SOUTHWEST ATLANTIC. AS FAR AS PRECIPITATION IS CONCERNED...ONLY LIGHT RAIN AND DRIZZLE ARE EXPECTED EARLY IN THE WEST UNDER THE CAD REGIME...BUT LATER IN THE EVENING AS THE HIGH SLIDES OUT TO SEA...MORE CONVECTIVE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE WEDNESDAY EVENING INTO WEDNESDAY NIGHT. CAPE IS TALL AND SKINNY AND MOISTURE IS VERY LIMITED TO THE LOW LEVELS BUT ANY CAPPING THAT IS IN PLACE INITIALLY AROUND THE 700 MB LEVEL WILL EVENTUALLY ERODE OVERNIGHT...SETTING UP MORE FAVORABLE CONDITIONS FOR CONVECTION ON WEDNESDAY NIGHT AND INTO THE DAY ON THURSDAY. WIND SHEAR WILL BE VERY FAVORABLE FOR CONVECTION AS 40 KTS OR SO OF BULK SHEAR IS EXPECTED. RAIN CHANCES WILL INCREASE SIGNIFICANTLY AFTER 6Z THURSDAY. A NON-DIURNAL TEMPERATURE TREND IS EXPECTED AS THE CAD BREAKS DOWN AND A SURFACE WARM FRONT WORKS NORTHWARD THROUGH THE AREA. THEREFORE NEAR STEADY TO SLIGHTLY INCREASING TEMPERATURES AFTER 00Z THURSDAY WILL MORE RAPIDLY INCREASE EARLY THURSDAY MORNING. LOWS LISTED IN THE LOW TO UPPER 50S BUT AGAIN THIS WILL OCCUR EARLIER WEDNESDAY NIGHT AS OPPOSED TO THURSDAY MORNING. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... AS OF 330 AM WEDNESDAY... STRONG COLD FRONT WILL BE OFFSHORE OR MOVING OFFSHORE BY FRIDAY MORNING AND STRONG COLD AIR ADVECTION WILL BE UNDERWAY TO OFFSET THE POTENTIAL FOR LIMITED INSOLATION. LINGERING ANAFRONTAL SHOWERS DRIVEN BY THE COLD AIR ADVECTION WILL LINGER IN THE EAST THROUGH MID DAY. THESE WILL BE FOLLOWED DURING THE AFTERNOON INTO EARLY EVENING BY ADDITIONAL LIGHT SHOWERS WHICH WILL BE FORCED BY A TRAILING MID LEVEL SHORT WAVE WHICH WILL HAVE SUFFICIENT LINGERING MOISTURE IN THE LOW LEVELS ABOVE THE MIXING LEVEL TO PRODUCE SCATTERED SHALLOW CONVECTION. HIGHS WILL BE IN THE MID 50S WEST TO UPPER 50S EAST. LINGERING CLOUD COVERAGE AND OVERNIGHT MIXING WILL FORTUNATELY AID IN SOFTENING THE TEMPERATURE CRASH FRIDAY NIGHT AS LOW LEVEL THICKNESSES FALL NEARLY 100 METERS (25-30 DEGREES BY RULE OF THUMB) IN THE 24 HOUR PERIOD FROM FRIDAY MORNING TO SATURDAY MORNING. GUIDANCE HAS BEEN CONSISTENTLY INDICATING MID TO UPPER 30S...AND WILL CONTINUE THIS TREND WITH A WARY EYE ON THE POSSIBILITY THAT CLEARER/CALMER CONDITIONS MIGHT ALLOW US TO RADIATE LOWER. THE UPPER TROF AXIS IS OVER THE AREA ON SATURDAY AND HIGHS WILL STALL IN THE UPPER 40S ACROSS THE NORTHERN TIER TO LOWER 50S ELSEWHERE AS THE COLD AIR ADVECTION OFFSETS INCREASED SUNSHINE AS SURFACE HIGH PRESSURE MIGRATES EAST INTO THE MID ATLANTIC. AS THE HIGH BUILDS IN...RADIATIONAL CONDITIONS WILL BE NEAR IDEAL ON SATURDAY NIGHT AND SUNDAY MORNINGS DAWN MINS WILL BE IN THE UPPER 20S NORTH TO NEAR FREEZING IN THE SOUTH. WE WILL BEGIN TO SEE MODIFICATION OF THE AIRMASS SUNDAY UNDER STRONG SUN AND NEUTRAL TEMPERATURE ADVECTION...AND HIGHS WILL BE MOSTLY IN THE MID 50S. WE HAVE LOW LEVEL RETURN FLOW AND SLOWLY RISING H5 HEIGHTS SUNDAY NIGHT INTO MONDAY TO INITIATE A MODERATING TREND IN THE TEMPS. A FAST MOVING SHORT WAVE AND ASSOCIATED FRONT WILL DIVE SOUTHEAST AND ACROSS THE AREA ON MONDAY...AND WHILE WE COULD SEE SOME SHOWERS SQUEEZED OUT BY THIS SYSTEM...THEY WOULD BE LIGHT AS ITS LIMITED AVAILABLE MOISTURE WILL BE PRECIPITATED OUT AS IT MOVES ACROSS THE MOUNTAINS. WILL MAINTAIN A DRY FORECAST FOR NOW WITH HIGHS MONDAY AND TUESDAY REACHING THE 60S AFTER MORNING LOWS FROM 40 TO 45. WEDNESDAY IS LOWER CONFIDENCE...BUT LOOKS TO BE DRY WITH HIGHS REACHING THE LOWER 70S. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 200 AM WEDNESDAY... 24-HR TAF PERIOD: EXPECT CEILINGS TO DETERIORATE TO MVFR/IFR AT ALL TERMINALS THIS MORNING IN ASSOC/W LOW-LEVEL WARM ADVECTION ATOP A COOL SFC AIRMASS RECENTLY DEPOSITED IN THE WAKE OF A BACKDOOR COLD FRONT PROGRESSING SOUTHWESTWARD THROUGH CENTRAL NC. CEILINGS ARE EXPECTED TO RANGE FROM 700-1200 FT AGL AT ALL TERMINALS BY 12Z... WITH AN EASTERLY WIND AT 5-10 KT. RWI/FAY/RDU: CEILINGS SHOULD GRADUALLY LIFT TO HIGH-END MVFR OR LOW- END VFR (2500-3500 FT AGL) BY EARLY AFTERNOON WHERE THE CAD WEDGE WILL GIVE WAY TO A WARM FRONT PROGRESSING WESTWARD TO THE HWY 1 CORRIDOR. MVFR/VFR CONDITIONS WILL PREVAIL THE REMAINDER OF THE AFTERNOON...THOUGH CEILINGS WILL LIKELY DETERIORATE TO IFR A FEW HOURS AFTER SUNSET...BY THE END OF THE 06Z TAF PERIOD. INT/GSO: FURTHER NW WHERE THE CAD WEDGE WILL REMAIN FIRMLY IN PLACE...IFR/MVFR CEILINGS (~1000 FT AGL) ARE EXPECTED TO PREVAIL THROUGH THE ENTIRE TAF PERIOD...WITH FURTHER DETERIORATION TO LIFR (CEILINGS 200-400 FT AGL) LIKELY BY THE END OF THE TAF PERIOD. LOOKING AHEAD: ADVERSE AVIATION CONDITIONS WILL PREVAIL THE REMAINDER OF THE WORK WEEK. CEILINGS ARE EXPECTED TO IMPROVE TO MVFR AND POSSIBLY VFR DURING THE DAY THU AS A WARM SECTOR BECOMES MORE FIRMLY ESTABLISHED OVER CENTRAL NC...THOUGH CEILINGS WILL LIKELY TAKE LONGER TO IMPROVE AT THE INT/GSO TERMINALS AND MAY REMAIN SUB- VFR THE ENTIRE DAY. ISOLD TO SCT CONVECTION CANNOT BE RULED OUT AT ANY TERMINAL THU AFT/EVE INTO THU NIGHT AS A COLD FRONT PROGRESSES INTO THE REGION FROM THE NW. OVERCAST MVFR/IFR CEILINGS WILL RETURN EARLY FRI MORNING IN THE WAKE OF THE FRONT...PERSISTING THROUGH THE DAY AT EASTERN TERMINALS...BEFORE STRONG COLD ADVECTION ARRIVES AND ALLOWS IMPROVEMENT FRI NIGHT. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...MLM AVIATION...VINCENT

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