Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 251929 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 335 PM EDT WED MAR 25 2015 .SYNOPSIS...HIGH PRESSURE EXTENDING SOUTH OVER THE MID-ATLANTIC REGION WILL SHIFT OUT INTO THE ATLANTIC TODAY. THIS WILL ALLOW A WARM FRONT TO LIFT NORTH THROUGH THE STATE OVERNIGHT. A COLD FRONT WILL APPROACH SLOWLY FROM THE WEST ON THURSDAY AND WILL CROSS THE AREA THURSDAY NIGHT. && .NEAR TERM /TONIGHT/...
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AS OF 335 PM WEDNESDAY... STRONG INFLUX OF ATLANTIC MOISTURE WITHIN A STRENGTHENING H9 35-40KT SOUTHERLY LLJ WILL OVERSPREAD THE AREA OVERNIGHT... SUPPORTING SCATTER TO NUMEROUS SHOWERS AND POSSIBLY A RUMBLE OF THUNDER OR TWO AS AS WEAK INSTABILITY DEVELOPS(MUCAPE(400-600 J/KG)OWING TO STEEP MID-LVL LAPSE RATES OVER THE AREA. AS FAR AS SEVERE POTENTIAL...WHILE FAVORABLE EFFECTIVE SHEAR OF 35KTS COULD SUPPORT SOME ROTATION WITH THE STRONGER CELLS...THE ABSENCE OF FORCING OUTSIDE OF LOW-LEVEL WAA COUPLED WITH SHALLOW DEPTH OF MOISTURE WILL LIMIT SEVERE POTENTIAL. EXPECT NEAR STEADY TEMPS OVERNIGHT WITHIN THE LINGERING CAD WEDGE IN PLACE IN THE TRIAD...PERHAPS RISING A FEW DEGREES BY SUNRISE. ELSEWHERE...EXPECT LOWS IN THE LOWER TO MID 60S.
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&& .SHORT TERM /THURSDAY AND THURSDAY NIGHT/...
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AS OF 335 PM WEDNESDAY... THURSDAY: OWING TO THE SLOWER ARRIVAL OF THE FRONT INTO THE AREA...NOW DELAYED UNTIL AFTER 00Z FRIDAY...ONCE CONVECTION EXITS THE COASTAL PLAIN THURSDAY MORNING...THURSDAY LOOKS TO BE MOSTLY DRY ACROSS CENTRAL NC. IT WILL BE MUCH WARMER AS WELL. AS LOW-LEVEL FLOWS TO VEER AROUND A MORE SWLY COMPONENT...DRIER AIR WILL ADVECT INTO THE AREA FROM THE SW WHICH WILL HELP TO SCOUR LINGERING LOW CLOUDS/MOISTURE AND YIELD PARTLY TO MOSTLY SUNNY CONDITIONS THURSDAY AFTERNOON. WARM SECTOR TEMPERATURES WILL RISE WELL INTO THE 70S ACROSS THE AREA...APPROACHING NEAR 80 ACROSS THE FAR SE ZONES. THURSDAY NIGHT: COLD FRONT WILL CROSS THE AREA FROM WEST TO EAST BETWEEN 03 TO 12Z THURSDAY NIGHT/EARLY FRIDAY MORNING. CHANCE OF THUNDER LOOKS LOW APPEARS QUESTIONABLE GIVEN UNFAVORABLE DIURNAL TIMING AND LACK OF SUPPORT ALOFT AS THE AMPLIFYING UPPER LEVEL TROUGH IS PROGGED TO LAG BEHIND THE COLD FRONT. HOWEVER...BOTH THE GFS AND EC INDICATE THE POTENTIAL FOR WEAK DISTURBANCES IN ADVANCE OF THE MAIN TROUGH THAT COULD ENHANCE FORCING BETWEEN 00 TO 06Z ACROSS THE AREA WITH LINGERING STEEP MID-LEVEL LAPSE RATES AROUND 7.0 DEG/KM ACROSS THE WESTERN PIEDMONT. WILL INCLUDE A SLIGHT CHANCE OF THUNDER ACROSS THE NW PIEDMONT...WITH SHOWERS ELSEWHERE DUE TO WANING INSTABILITY AS THE FRONT CROSSES THE AREA. ANAFRONTAL PRECIP WILL THEN FILL IN BEHIND THE FRONT WITH THE APPROACH OF THE AMPLIFYING TROUGH INTO THE SOUTHERN APPALACHIANS AND ENSUING STRONG LOW-LEVEL CAA. LOWS RANGING FROM UPPER 40S/LOWER 50S NW TO LOWER/MID 60S ACROSS THE SE DEPENDING ON THE EXACT TIMING OF THE COLD FRONT.
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&& .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 /18Z WEDNESDAY THROUGH SUNDAY/... AS OF 215 PM WEDNESDAY... 24-HR TAF PERIOD: AMIDST WEAK LOW-LEVEL WARM ADVECTION ATOP A SHALLOW COOL DRY SFC AIRMASS...KINT AND KGSO WILL MAINTAIN MVFR CEILINGS WITH A SLIGHT CHANCE OF LIGHT RAIN OR DRIZZLE THROUGH THE AFTERNOON. AT RWI/FAY...CEILINGS HAVE LIFTED TO VFR 5000-9000 FT AGL) AND SHOULD REMAIN THROUGH THE REMAINDER OF THE AFTERNOON. SADDLED IN BETWEEN...RDU WILL BE ON THE THRESHOLD OF HIGH-END MVFR/LOW END VFR WITH CEILINGS GENERALLY 2500-3500 KFT. CONDITIONS ARE EXPECTED TO DETERIORATE LATE THIS EVENING AND INTO THE OVERNIGHT HOURS AS STRONG WARM MOIST AIR ADVECTION WITHIN A A STRENGTHENING 35-40KT 925MB LOW-LEVEL JET OVERSPREADS THE AREA OVERNIGHT. EXPECT CEILINGS TO LOWER TO IFR AND PERHAPS LIFR OVERNIGHT WITH SCATTERED TO NUMEROUS SHOWERS AND POSSIBLY A THUNDERSTORM OR TWO POSSIBLE. ADDITIONALLY...AS THE LOW-LEVEL JET LIFTS ACROSS THE AREA...KINT AND KGSO MAY EXPERIENCE LLWS BETWEEN 03 TO 12Z AS CAD WEDGE MAY HOLD IN PLACE. WILL NOT INCLUDE ANY LLWS AT THIS TIME...BUT LLWS MAY BE ADDED WITH THE EVENING(00Z)PACKAGE. CEILINGS ARE EXPECTED TO IMPROVE TO VFR DURING THE DAY ON THURSDAY AS AS A WARM SECTOR BECOMES MORE FIRMLY ESTABLISHED AND DRIER AIR MOVES INTO THE AREA FROM THE SOUTHWEST. BREEZY SWLY WINDS OF 20 TO 25KTS ARE ALSO EXPECTED THURSDAY AFTERNOON. LOOKING AHEAD: A COLD FRONT WILL CROSS THE AREA THURSDAY NIGHT. SCATTERED SHOWERS ARE POSSIBLE AHEAD OF THE FRONT...BUT PRECIP WILL BE MOSTLY ANA-FRONTAL WITH CATEGORICAL RAIN CHANCES AND MVFR/IFR CEILINGS RETURNING EARLY FRI MORNING...PERSISTING THROUGH THE DAY AT EASTERN TERMINALS. THE RETURN OF VFR CONDITIONS LATE FRIDAY AFTERNOON/EVENING COULD BE TEMPORARILY DELAYED UNTIL THE PASSAGE OF THE STRONG UPPER LEVEL TROUGH SATURDAY MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL NEAR TERM...CBL SHORT TERM...CBL LONG TERM...MLM AVIATION...CBL

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