Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 270220 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1015 PM EDT THU MAR 26 2015 .SYNOPSIS...A COLD FRONT WILL TRACK SOUTHEAST THROUGH CENTRAL NORTH CAROLINA LATE TONIGHT. THE COLD FRONT WILL BRIEFLY STALL OFFSHORE THE CAROLINA COAST ON FRIDAY AS A POTENT UPPER LEVEL DISTURBANCE APPROACHES FROM THE WEST. && .NEAR TERM /TONIGHT/... AS OF 1015 PM THURSDAY... THE SURFACE COLD FRONT MOVING THROUGH THE MOUNTAINS IS BEING PRECEDED BY A NARROW LINE OF SHOWERS...THOUGH THE BETTER COVERAGE IS NORTH OF THE NC/VA BORDER NEAR BLACKSBURG. MODELS STILL SHOW A RELATIVELY SLOW PROGRESSION OF THE FRONT THROUGH THE CWA TONIGHT...ONLY REACHING THE SANDHILLS AND SOUTHERN COASTAL PLAIN BY SUNRISE... WHILE THE UPPER TROUGH AXIS LAGS WELL TO THE WEST. THERE HAVE BEEN NO SHOWERS OVER CENTRAL NC THIS EVENING...MOSTLY OWING TO A GOOD CAP AT 700MB AND NO INSTABILITY. SOME COOLING AT 700MB IS EXPECTED OVER THE NEXT FEW HOURS...AND ALONG WITH A DISTURBANCE UPSTREAM OVER GA NOTED ON WATER VAPOR...SHOULD HELP TO ENHANCE THE COVERAGE OF SHOWERS AS THE FRONT MOVES THROUGH THE AREA. THE MOST RECENT HRRR SHOWS THE CURRENT PREFRONTAL SHOWERS MAKING LITTLE PROGRESS INTO THE PIEDMONT...WITH SOME REDEVELOPMENT ALONG THE FRONT AFTER 06Z. EVEN THEN THE COVERAGE IS NOT THAT GREAT...SO WILL BE REDUCING POPS A BIT OVERNIGHT...EXPECTING THE BEST COVERAGE TO COME POST-FRONTAL MORE TOWARD 12Z AS THE UPPER TROUGH NEARS THE AREA AND PW RISES TO 1 TO 1.25 INCHES. MOST GUIDANCE IS ALSO TOUCH WARMER WITH TEMPS THROUGH 12Z...LIKELY DUE TO THE COOLER AIR BEING SLOWED BY THE MOUNTAINS. USING SOME OF THE MOST RECENT HI-RES GUIDANCE YIELDS UPPER 40S NORTH TO UPPER 50S SOUTH. && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 315 PM THURSDAY... FRIDAY...WIDESPREAD SHOWERS IN THE MORNING WILL DIMINISH BY EARLY AFTERNOON...COINCIDING WITH THE PASSAGE OF THE 850-700MB TROUGHS. STRONG LOW LEVEL NLY FLOW WILL ADVECT COLDER AIR INTO THE REGION THROUGHOUT THE DAY. TEMPS WILL CONTINUE TO FALL THROUGH THE MORNING AND EARLY AFTERNOON HOURS...POSSIBLY STABILIZING BY MID AFTERNOON. FRIDAY NIGHT...UPPER LEVEL TROUGH CROSSES THE REGION...ACCOMPANIED BY A FEW SHOWERS. MODEL CROSS SECTIONS OF LIFT/MOISTURE DO DEPICT ENOUGH SATURATION IN THE ICE NUCLEATION REGION TO CAUSE SNOW TO FORM ALOFT. HOWEVER THE LOWER LAYERS ARE DRYING OUT TO SUCH A DEGREE THAT ANY SNOW THAT FALLS WILL LIKELY MELT AND/OR EVAPORATE BEFORE REACHING THE SURFACE. THUS WILL CONFINE MENTION OF PRECIP TO RAIN SHOWERS FOR NOW. LOWER LAYERS OF THE ATMOSPHERE REMAIN WELL MIXED THROUGH FRIDAY NIGHT. THIS MIXING ALONG WITH VARIABLY CLOUDY SKIES MAY AID TO KEEP TEMPS UP A BIT IN SPITE OF THE COLD AIR ADVECTION. SOME MOS GUIDANCE HAS MIN TEMPS BY EARLY SATURDAY IN THE UPPER 20S TO AROUND 30 OVER THE PIEDMONT. THIS SEEMS A LITTLE EXTREME SO AM MORE IN FAVOR OF MIN TEMPS NEAR FREEZING NW TO THE MID-UPPER 30S ELSEWHERE. IF SKIES ARE ABLE TO CLEAR AND SFC WINDS DECOUPLE...COULD SEE AN ARGUMENT FOR MIN TEMPS IN THE UPPER 20S-LOWER 30S. && .LONG TERM /SATURDAY THROUGH THURSDAY/... AS OF 245 PM THURSDAY... THIS WEEKEND: THE MAIN WEATHER STORY THIS WEEKEND WILL BE THE COLD TEMPERATURES... IN THE WAKE OF THE TROUGH THAT IS PROGGED TO PUSH ACROSS OUR AREA EARLY IN THE PERIOD. COLD HIGH PRESSURE WILL BUILD ACROSS OUR AREA FROM THE NW OVER THE WEEKEND...BRINGING AN AIRMASS THAT FEATURES LOW LEVEL THICKNESSES ABOUT 60M BELOW NORMAL. DESPITE MAINLY CLEAR SKIES AND AMPLE SUNSHINE DURING THE DAY...HIGHS SATURDAY WILL ONLY CLIMB TO THE UPPER 40S NORTH TO LOWER 50S SOUTH. SATURDAY NIGHT...LOOK FOR SUB-FREEZING LOW TEMPS ACROSS ALL OF CENTRAL NC...THANKS TO THE COMBINATION OF THE AFOREMENTIONED AIRMASS...MAINLY CLEAR SKIES AND CALM WIND UNDER THE HIGH PRESSURE CENTER. RIGHT NOW WE`RE SHOWING LOWS RANGING FROM THE MID 20S ACROSS THE TRIAD TO AROUND 30 ACROSS THE SOUTHERN COASTAL PLAIN...BUT WITH THE HIGH CENTERED OVER US BY 12Z SUN...THOSE TEMPS MAY END UP EVEN COLDER IN SPOTS. WE`LL BEGIN TO SEE SOME MODERATION ON SUNDAY AS THE HIGH CENTER SHIFTS TO OUR SOUTHEAST...BUT STILL ABOUT 10 DEG BELOW NORMAL...HIGHS IN THE MID 50S. SUNDAY NIGHT THROUGH THURSDAY: A SHORT WAVE IS PROGGED TO QUICKLY MOVE ACROSS OUR AREA SUNDAY NIGHT INTO MONDAY MORNING...BUT ASIDE FROM A FEW PASSING SPRINKLES...RIGHT NOW IT APPEARS THAT FEATURE WILL MOVE ACROSS MOSTLY DRY. HIGH PRESSURE WILL BRIEFLY BUILD ACROSS OUR AREA LATE MONDAY INTO TUESDAY...PRIOR TO THE NEXT COLD FRONT THAT IS PROGGED TO CROSS THE CAROLINAS ON WEDNESDAY. RIGHT NOW THAT FRONT APPEARS TO COME THROUGH DRY AS WELL...GIVEN THAT THE DEEPER MOISTURE AHEAD OF IT IS FORECAST TO REMAIN MOSTLY TO OUR SOUTH. RAIN CHANCES MAY INCREASE ON THURSDAY AS THE FRONT LIFTS BACK TO OUR NORTH AS A WARM FRONT AHEAD OF A FAST-MOVING SOUTHERN STREAM SHORT WAVE. AS FOR TEMPERATURES DURING THIS TIME....LOOK FOR A GRADUAL WARMUP...WITH READINGS CLOSER TO NORMAL THANKS TO THE PATTERN DEAMPLIFYING AND BECOMING MORE ZONAL WITH TIME ACROSS OUR AREA. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 840 PM THURSDAY... VFR CONDITIONS WILL PREVAIL IN ADVANCE OF A COLD FRONT THAT WILL MOVE SOUTHEAST ACROSS CENTRAL NC TONIGHT...WITH TIMING THROUGH INT AND GSO BETWEEN 03-05Z; RDU AND RWI BETWEEN 06-08Z; AND FAY BETWEEN 09-12Z. THE PASSAGE OF THE FRONT WILL RESULT IN A SHARP WIND SHIFT FROM SSW TO NW AND BE ACCOMPANIED BY A NARROW BAND OF LOW-TOPPED SHOWERS (AND POSSIBLY AN ISOLATED THUNDERSTORM) WITH GUSTY NW WINDS. POST-FRONTAL RAIN AND MVFR-IFR CONDITIONS WILL FOLLOW THE FRONT... THOUGH IT MAY TAKE SEVERAL HOURS BEHIND THE FRONT FOR ANY SUCH SUB- VFR CONDITIONS TO BECOME PREVAILING CONDITIONS. WINDS WILL THEN GRADUALLY VEER TO A MORE NORTHERLY TO NORTHEASTERLY COMPONENT BETWEEN 12-18Z...AT WHICH TIME BLUSTERY SUSTAINED WINDS AND GUSTS WILL BE PROBABLE - HIGHEST AT EASTERN TAF SITES. RAIN WILL END FROM WEST TO EAST AFTER 18Z FRI...WITH AN ACCOMPANYING IMPROVEMENT IN FLIGHT CATEGORY TO MVFR...OR LIFTING AND SCATTERING TO VFR...BY LATE AFTERNOON - SLOWEST AT EASTERN TERMINALS. OUTLOOK: A BRIEF PERIOD OF SUB-VFR CONDITIONS MAY REDEVELOP WITH THE PASSAGE OF AN UPPER LEVEL DISTURBANCE FRI NIGHT...PARTICULARLY AT EASTERN TAF SITES. OTHERWISE...THERE WILL BE A THREAT OF MVFR CEILINGS WITH THE PASSAGE OF ANOTHER COLD FRONT SUN NIGHT. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS/22 SHORT TERM...WSS LONG TERM...RAH AVIATION...RAH

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