Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 031532 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1030 AM 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 THIS AFTERNOON COULD WARM INTO THE 40S ACROSS MUCH OF THE AREA...RANGING FROM NEAR TO LOWER 40 NORTH TO UPPER 40S/NEAR 50 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 MONDAY/... AS OF 400 AM TUESDAY... THE LATEST MODELS ARE IN GOOD AGREEMENT IN BRING THE COLD FRONT SOUTH THROUGH CENTRAL NORTH CAROLINA THURSDAY MORNING. A WAVE IS EXPECTED TO FORM ALONG THE FRONT OVER UPSTATE SC... WHICH IN TURN HELPS TO HOLD UP THE COLD FRONT FOR SEVERAL HOURS FROM REACHING THE SOUTHERN ZONES. THE STRONGEST CAA SHOULD ALSO LAG THE FRONTAL PASSAGE BY SEVERAL HOURS IT APPEARS. THIS SUPPORTS THE CONTINUATION OF OUR CURRENT PREDOMINATELY RAIN FORECAST FOR THURSDAY WITH LIMITED POTENTIAL FOR WINTERY MIX NEAR THE END OF THE EVENT BETWEEN 18Z AND 23Z OR SO THURSDAY AFTERNOON FOR THE NORTHERN PIEDMONT AND NORTHERN COASTAL PLAIN. P-TYPE NOMOGRAMS SUPPORT SOME MIX WITH OR CHANGE TO FREEZING RAIN THEN EVEN A BRIEF PERIOD OF LIGHT SNOW/SLEET AT THE VERY VERY END OF THE EVENT...ACROSS THE FAR NORTHERN PIEDMONT DURING THE MID TO LATE AFTERNOON. FORECAST WET BULB TEMPERATURES DEPENDING ON THE MODEL OF CHOICE WITH SOME MODEL VARIABILITY ALSO TARGET THE NORTHERN ZONES FOR THIS POTENTIAL CHANGEOVER (ESPECIALLY NORTH OF A LINE EXTENDING FROM DAVIDSON TO RANDOLPH TO WAKE TO WARREN COUNTIES. PRECIPITATION SHOULD END QUICKLY BETWEEN 21Z-00Z...LIMITING THE WINDOW OF OPPORTUNITY FOR ICE TO BECOME A SIGNIFICANT WEATHER HAZARD. TO THE SOUTH...ALL RAIN IS EXPECTED WITH THE SLOWER TO COOL TEMPERATURES THERE. ALL IN ALL...A SIGNIFICANT WINTER WEATHER EVENT IS NOT EXPECTED AT THIS TIME WITH THE PREDOMINATE P-TYPE EXPECTED TO BE RAIN. THE CHANGEOVER WOULD OCCUR DURING THE AFTERNOON IN THE NORTH (IF AT ALL)... AND THE WARM GROUND TEMPERATURES AND TIME OF DAY WOULD LIMIT THE POTENTIAL TO MOSTLY ELEVATED SURFACES. THURSDAY NIGHT...BREEZY AND COLDER CONDITIONS COULD LEAD TO A QUICK FREEZE OF RESIDUAL WATER LEFT BEHIND WHICH MAY BECOME A WEATHER HAZARD. OTHERWISE...SIMPLY CLEARING AND COLD WITH LOWS IN THE 20-25 RANGE. FRIDAY IS EXPECTED TO BE MOSTLY SUNNY AND COLD WITH THE HEART OF THE ARCTIC COLD EXPECTED OVER THE OHIO VALLEY AND NORTHERN MID ATLANTIC STATES. WE WILL STILL BE A GOOD 20 DEGREES BELOW NORMAL WITH HIGHS EXPECTED IN THE UPPER 30S TO LOWER 40S. MODERATION WILL OCCUR IN THE TEMPERATURES OVER THE WEEKEND AS THE HIGH SLIPS SOUTH AND A WESTERLY FLOW DEVELOPS. HIGHS SHOULD RAPIDLY WARM INTO THE MID 40S TO LOWER 50S SATURDAY AND MID 50S TO LOWER 60S SUNDAY. A DRIER PATTERN IS ALSO ANTICIPATED THROUGH THE WEEKEND. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 730 AM TUESDAY... 24-HR TAF PERIOD: DETERIORATING CONDITIONS EXPECTED THROUGH THE TAF PERIOD...ESPECIALLY THIS EVENING INTO TONIGHT WHEN 1/4SM +FG VV001 IS EXPECTED AT MOST OR ALL TERMINALS. CEILINGS WILL LOWER TO MVFR THIS MORNING AND LOW MVFR/IFR THIS AFTERNOON AS POCKETS OF LIGHT RAIN AND DRIZZLE DEVELOP SW-NE ACROSS THE REGION IN ASSOC/W PERSISTENT WARM ADVECTION. 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 ~03Z. AVIATION CONDITIONS WILL REMAIN POOR THROUGH THE REMAINDER OF THE TAF PERIOD (12Z WED). LOOKING AHEAD: CEILINGS WILL IMPROVE WED MORNING AS A WARM FRONT PROGRESSES THROUGH THE REGION AND A BREEZY SW FLOW DEVELOPS...THOUGH MVFR CEILINGS MAY PERSIST THROUGH THE DAY. SOUTHWEST WINDS MAY BECOME SUSTAINED AT 20-25 KT WITH GUSTS AS HIGH AS 30-35 KT WED AFTERNOON...DEPENDING ON CLOUD COVER/MIXING. ADVERSE AVIATION CONDITIONS ARE EXPECTED TO PREVAIL THU/THU NIGHT IN ASSOC/W A COLD FRONTAL PASSAGE EARLY THU AND SUBSEQUENT CAD WEDGE DEVELOPMENT THU AFTERNOON/EVENING. A PERIOD OF VFR CONDITIONS IS EXPECTED ON FRIDAY...THOUGH ADVERSE CONDITIONS APPEAR LIKELY ONCE AGAIN OVER THE WEEKEND. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...CBL/VINCENT SHORT TERM...VINCENT LONG TERM...BADGETT AVIATION...VINCENT

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