Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 031953 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 253 PM EST TUE MAR 3 2015 .SYNOPSIS...HIGH PRESSURE OVER THE REGION WILL SHIFT OFFSHORE THIS AFTERNOON AS A LOW PRESSURE SYSTEM TRACKS NORTHEAST FROM THE CENTRAL PLAINS INTO THE GREAT LAKES. A WARM FRONT WILL LIFT NORTHWARD THROUGH THE REGION LATE TONIGHT AND EARLY WEDNESDAY. THE NEXT COLD FRONT WILL APPROACH FROM THE NORTHWEST WEDNESDAY NIGHT...TRACKING THROUGH THE CAROLINAS ON THURSDAY. && .NEAR TERM /TODAY AND TONIGHT/... AS OF 1030 AM TUESDAY... OVERVIEW: A 1030MB SURFACE HIGH CENTERED OVER THE MID-ATLANTIC STATES THIS MORNING WILL SHIFT OFFSHORE THIS AFTERNOON. WELL DOWNSTREAM OF THE SURFACE LOW MOVING EAST-NORTHEASTWARD INTO THE LOWER GREAT LAKES...BROAD REGION OF LOW AND MID-LEVEL WARM ADVECTION ATOP THE RESIDUAL SHALLOW WEDGE OF COOL/DRY AIR NEAR THE SFC WILL SUPPORT COLD AIR DAMMING ACROSS THE CAROLINAS TODAY. THE WEDGE OF COOL DRY AIR WILL THEN RETREAT NORTHWARD OVERNIGHT AS A WARM FRONT LIFTS NORTHWARD THROUGH THE AREA. TODAY: LITTLE IF ANY UPPER LEVEL FORCING WILL BE PRESENT AS RIDGING OVER THE GULF OF MEXICO BUILDS NORTHWARD OVER THE SOUTHEAST. AS A RESULT...PRECIP CHANCES WILL BE VERY LIGHT...WITH INTERMITTENT PERIODS OF LIGHT RAIN/DRIZZLE EXPECTED ACROSS THE AREA THROUGHOUT THE DAY. IN FACT THE LATEST HRRR...SHOWS VERY LITTLE COVERAGE ACROSS THE AREA THROUGH THE AFTERNOON. DAYTIME HIGHS WILL ULTIMATELY DEPEND ON THE EXTENT/COVERAGE OF PRECIP. WITHOUT DECENT COVERAGE OF PRECIP ACROSS THE AREA AND THE BENEFITS OF ASSOCIATED EVAP COOLING...TEMPERATURES ARE EXPECTED TO RANGE FROM MID/UPPER 30S NORTH TO LOWER/MID 40S SOUTHEAST. TONIGHT: LOW CONFIDENCE WITH TEMPERATURES OVERNIGHT...WRT TO WARM FRONT LIFTING NORTHWARD INTO CENTRAL NC AND THE WESTERN/INLAND EXTENT OF CAD EROSION OVERNIGHT. GIVEN THE LACK OF A WELL DEFINED UPSTREAM CYCLONE...ONE WOULD TYPICALLY BE SKEPTICAL OF SIGNIFICANT CAD EROSION DURING THE OVERNIGHT HOURS AS DEPICTED BY THE GFS WHICH BLOWS AWAY THE DAMMING REGIME EVEN INTO THE HEART OF THE WEDGE ACROSS THE NW PIEDMONT. HOWEVER...GIVEN THE POTENTIAL LACK OF SIGNIFICANT PRECIP TO HELP LOCK IN THE WEDGE...THE GFS SCENARIO REMAINS PLAUSIBLE. IN CONTRAST...THE HIGHER RESOLUTION NAM...WHICH TYPICALLY HANDLES CAD EVOLUTION BETTER ACROSS THE CAROLINAS...KEEPS THE WEDGE IN PLACE WITH TEMPS NEARLY STEADY AND GRADUALLY/MARGINALLY INCREASE BY SUNRISE...PARTICULARLY NORTH OF HWY 64. WILL ERR TOWARDS THE COOLER GUIDANCE...BUT THERE REMAINS HIGH BUST POTENTIAL. WARM AIR LIFTING ATOP THE SHALLOW COOL AIR WILL SUPPORT AN ENHANCED POTENTIAL FOR THE DEVELOPMENT OF DENSE FOG OVERNIGHT. && .SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/... AS OF 400 AM TUESDAY... IF THE WARM FRONT HAS NOT PROGRESSED THROUGH THE BULK OF CENTRAL NC BY SUNRISE WED...IT SHOULD DO SO SHORTLY THEREAFTER AS THE INCREASINGLY SHALLOW CAD WEDGE DISSIPATES VIA INCREASING INSOLATION/MIXING AND STRENGTHENING SOUTHWEST FLOW. INITIALLY OVERCAST SKIES WILL BECOME SCT/BKN BY AFTERNOON...WITH A BREEZY SOUTHWEST WIND. THE GFS SUGGESTS DEEP/MORE VIGOROUS MIXING AND A POTENTIAL FOR GUSTS AS HIGH AS 30-40 KT...THOUGH THE NAM INDICATES LESS MIXING AND GUSTS NO HIGHER THAN 20-25 KT. GIVEN LITTLE IN THE WAY OF DIURNAL DESTABILIZATION....UNIDIRECTIONAL SW FLOW ALOFT WITH FEW (IF ANY) SHORTWAVE DISTURBANCES...AND UNIDIRECTIONAL SW LOW- LEVEL FLOW...EXPECT LARGELY DRY CONDITIONS OVER CENTRAL NC DURING THE DAY. AN AMPLIFYING TROUGH DIGGING SE INTO THE CENTRAL MS RIVER VALLEY WED EVE/NIGHT WILL RESULT IN CYCLOGENESIS ALONG A SLOW MOVING FRONTAL ZONE PROGRESSING INTO THE AREA WED NIGHT...THOUGH THE BULK OF PRECIPITATION IS EXPECTED TO BE ANAFRONTAL...OCCURRING AFTER SUNRISE. RAIN CHANCES WILL BE RELATIVELY HIGHEST NEAR THE VA BORDER AND IN THE NW PIEDMONT /TRIAD/. -VINCENT && .LONG TERM /THURSDAY THROUGH TUESDAY/... AS OF 300 PM TUESDAY... THURSDAY AND THURSDAY NIGHT: BY 12Z ON THURSDAY...PRECIPIATION ASSOCIATED WITH THE APPROACHING COLD FRONT WILL HAVE WORKED INTO NORTHERN SECTIONS OF THE CWA. AT THIS TIME ALL MODELS ARE HINTING AT THE FORMATION OF A SMALL MESO-LOW FORMING OVER UPSTATE SOUTH CAROLINA. THIS COULD ACT TO TEMPORARILY INCREASE PRECIPITATION OVER CENTRAL NC DURING THE DAYTIME HOURS AS FLOW BECOMES MORE SOUTHEASTERLY AND LOW LEVEL CONVERGENCE INCREASES. THIS FEATURE WILL QUICKLY ADVECT AWAY BY THURSDAY NIGHT. THE MAIN COLD FRONT HOWEVER WILL LINGER OVER THE AREA WITH A SOUTHWEST TO NORTHEAST ORIENTATION AS THE UPPER LEVEL TROUGH REALLY LAGS BACK OVER THE CENTRAL PLAINS ON THURSDAY AND THE REAL DRIVING FORCE PUSHING IT THROUGH WILL BE A SURFACE HIGH BACK ACROSS THE TENNESSEE VALLEY. THE EXTREMELY WARM TEMPERATURES FROM WEDNESDAY WILL QUICKLY COME CRASHING BACK TO REALITY AS TEMPERATURES DROP THROUGH THE DAY IN THE NORTH AND ONLY RISE BRIEFLY IN THE SOUTH BEFORE THE FRONT PASSES AND TEMPERATURES EVENTUALLY DROP BACK BELOW FREEZING THURSDAY NIGHT. THE COLD AIRMASS WILL BE CHASING THE PRECIPITATION AND AT LEAST IN SECTION NORTH OF HIGHWAY 64 THERE IS A GOOD CHANCE FOR A WINTRY MIX OF PRECIPITATION AT THE END OF THE EVENT THURSDAY NIGHT. PRIMARY TIMING WOULD BE BETWEEN 00Z AND 06Z WITH SLEET THE MOST LIKELY FROZEN PRECIPITATION TYPE. NORTHEASTERN COUNTIES MAY ALSO SEE A BRIEF PERIOD OF FREEZING RAIN AT THE INITIAL TRANSITION AROUND 00Z BUT THEN ALSO CHANGING OVER TO SLEET. FORECAST SOUNDINGS SUPPORT THIS WITH A VERY WARM NOSE INITIALLY AS TEMPERATURES AT THE SURFACE DROP BELOW FREEZING AT THE SURFACE. THIS WARM NOSE WILL ERODE RATHER QUICKLY AND JUST BELOW THAT AN EQUALLY STRONG COLD NOSE DEVELOPS...SUGGESTING THAT ANY REMAINING PRECIPITATION WILL REFREEZE PRIOR TO HITTING THE SURFACE. THE GOOD NEWS IS THAT MOST SREF MEMBERS POINTING TO THE VAST MAJORITY OF PRECIPITATION ENDING PRIOR TO THE CHANGEOVER TO FREEZING P-TYPES. AS A RESULT NO ICE ACCUMULATION AND VERY LITTLE SLEET ACCUMULATION IS EXPECTED...ESPECIALLY WHEN FACTORING IN VERY WARM GROUND TEMPERATURES FROM WEDNESDAY. MOST PRECIPITATION SHOULD WORK ITS WAY OUT OF THE AREA AROUND OR JUST AFTER 6Z. FRIDAY THROUGH SUNDAY NIGHT: THE WEEKEND WILL FEATURE DRIER WEATHER WITH THE FRONTAL ZONE LOOMING JUST TO OUR SOUTH. A TRANSITORY SURFACE HIGH WILL CONTROL THE WEATHER PATTERN INITIALLY FOSTERING COLD TEMPERATURES ON THE EASTERN SIDE OF THE HIGH AND THEN MODERATING NICELY THROUGH THE WEEKEND. INITIALLY HIGHS IN THE UPPER 30S/LOW 40S ON FRIDAY RISING TO MID TO UPPER 50S BY THE END OF THE WEEKEND. LOWS SLIGHTLY BELOW FREEZING FRIDAY TO SLIGHTLY ABOVE ON SUNDAY NIGHT. MONDAY THROUGH TUESDAY: SOLUTIONS DIVERGE EARLY NEXT WEEK IN REGARDS TO THE STRENGTH OF THE UPPER LEVEL TROUGH AND A LOW PRESSURE SYSTEM COMING OUT OF THE GULF OF MEXICO THAT COULD AFFECT OUR AREA EARLY NEXT WEEK. TEMPERATURES LOOK WARM ENOUGH THAT ANY PRECIPITATION SHOULD BE LIQUID. HIGHS IN THE UPPER 50S TO LOW 60S. LOWS IN THE MID TO UPPER 30S. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... AS OF 122 PM TUESDAY... 24-HR TAF PERIOD: EXPECT WIDESPREAD MVFR CONDITIONS THIS AFTERNOON...LOWERING TO IFR IN POCKETS OF LIGHT RAIN AND DRIZZLE. CEILINGS WILL LOWER TO IFR/LIFR AFTER SUNSET...QUICKLY FOLLOWED BY VISBYS FALLING TO LIFR/VLIFR WITH WIDESPREAD DENSE FOG AS A WARM FRONT PROGRESSES NORTHWARD INTO THE COLD AIR DAMMING WEDGE IN PLACE OVER CENTRAL NC AFTER 05-06Z. CEILINGS ARE EXPECTED TO IMPROVE FROM SE TO NW AS STRONG SWLY FLOW HELPS TO LIFT AND SCOUR OUT LINGERING WEDGE AIRMASS IN PLACE...POSSIBLY IMPROVING TO VFR AT KFAY...KRWI AND KRDU...WHILE MVFR CEILINGS MAY PERSIST AT KINT AND KGSO. BREEZY SOUTHWEST WINDS ARE EXPECTED TO DEVELOP BY THE AFTERNOON AS TEMPERATURES START TO WARM INTO THE 60S AND 70S. SUSTAINED WINDS OF 15 TO 20KTS WITH GUSTS AS HIGH AS 30-35 KT ...DEPENDING ON CLOUD COVER/MIXING. LOOKING AHEAD: ADVERSE AVIATION CONDITIONS ARE EXPECTED TO RETURN WEDNESDAY NIGHT AND WILL PERSIST THROUGH THURSDAY IN ASSOC/W A STRONG COLD FRONTAL PASSAGE AND ATTENDANT ANA-FRONTAL PRECIP BAND THROUGH THE THE AREA. PRECIPITATION COULD END AS A BRIEF PERIOD OF SLEET AND FREEZING RAIN THURSDAY AFTERNOON AND EVENING. VFR CONDITIONS ARE EXPECTED TO RETURN ON FRIDAY...AND SHOULD REMAIN PREDOMINATELY VFR THROUGH THE WEEKEND. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...CBL/VINCENT SHORT TERM...VINCENT LONG TERM...ELLIS AVIATION...CBL

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