Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 220010 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 709 PM EST FRI NOV 21 2014 .SYNOPSIS...HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH SATURDAY. A STRONG LOW PRESSURE SYSTEM MOVING FROM THE SOUTH PLAINS INTO THE GREAT LAKES SUNDAY WILL SPREAD MOISTURE OVER THE REGION SUNDAY. ANOTHER COLD FRONT WILL MOVE ACROSS THE REGION EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 230 PM FRIDAY... HIGH PRESSURE WILL SETTLE SOUTHWARD OVER NC TONIGHT. CLEAR SKIES EXPECTED TONIGHT. THE WINDS SHOULD RELAX SOME AND VEER OVERNIGHT AS THE HIGH BUILDS IN. WITH THE CLEAR SKIES AND CALM TO LIGHT WINDS OVERNIGHT YIELDING GOOD RADIATIONAL COOLING CONDITIONS...EXPECT LOWEST TEMPERATURES IN THE NORTHEAST...AROUND 20 DEGREES...AND HIGHEST ACROSS THE SOUTH...MID 20S. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... AS OF 230 PM FRIDAY... LOW LEVEL THICKNESSES WILL RISE APPROX 30 METERS OR SO FROM TODAY... YIELDING HIGH TEMPERATURES ABOUT 3 DEGREES OR SO HIGHER...LOW TO MID 50S ACROSS THE AREA. WITH THE HIGH OVERHEAD...WINDS SHOULD REMAIN RELATIVELY LIGHT AROUND 5 KTS OR SO AND OUT OF THE SOUTH OR SOUTHWEST. THE HIGH WILL FLATTEN OUT AND SLOWLY DRIFT OFF THE NC COAST...ALLOWING A WARM FRONT TO MOVE INTO THE AREA FROM THE SOUTH OVERNIGHT AS WINDS BECOME MORE SOUTHEASTERLY TO EASTERLY BY 12Z SUNDAY. WITH THE MODELS HAVING SLOWED THE APPROACHING SYSTEM DOWN... ANY PRECIPITATION SHOULD HOLD OFF UNTIL AFTER 12Z. HOWEVER...THE HIGH CLOUDS THAT ARE EXPECTED TO BUILD IN ON SATURDAY WILL STICK AROUND OVERNIGHT AND AS LOW LEVEL MOISTURE INCREASES SO WILL THE CHANCE FOR LOW STRATUS TO DEVELOP TOWARD DAYBREAK SUNDAY. WITH THE INFLUX OF WARM MOIST AIR OVERNIGHT...EXPECT LOWS IN THE LOW TO MID 30S TO OCCUR WITHIN A COUPLE HOURS OF MIDNIGHT...BEFORE GRADUALLY INCREASING A FEW DEGREES BY SUNRISE. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AS OF 230 PM FRIDAY... FOR DAYTIME SUNDAY...LITTLE CHANGE IN FORECAST THINKING FROM RECENT CYCLES...WITH THE PRIMARY FEATURE BEING A FAST-MOVING SOUTHERN STREAM S/W TROUGH THAT WILL MOVE FROM TX IN THE MORNING NE TO THE OH VALLEY BY EVENING. INCREASING SOUTHERLY FLOW AHEAD OF THIS VIGOROUS SYSTEM WILL TRANSPORT ABUNDANT MOISTURE NORTHWARD ACROSS OUR AREA AS NOTED IN FORECAST SOUNDINGS SHOWING PWAT INCREASING FROM AROUND 1/2 INCH AT DAWN TO 1.5 TO 1.75 INCHES (HIGHEST EAST) BY 11 PM PRIOR TO TROUGH PASSAGE. WITH INCREASING SW FLOW ABOVE A LINGERING SFC RIDGE...RESULTING ISENTROPIC LIFT WILL PRODUCE THICKENING/LOWERING CLOUDS AND LIGHT RAIN GRADUALLY DEVELOPING FROM SW TO NE AS THE DAY PROGRESSES. AS FOR TIMING THE ONSET OF LIGHT RAIN...RIGHT NOW LOOKS LIKE IT MAY BEGIN ACROSS OUR SOUTHERN/WESTERN ZONES BY EARLY TO MID AFTERNOON...THE TRIANGLE REGION BY MID-LATE AFTERNOON...THEN OUR NORTHERN/VA-BORDER ZONES BY SUNSET. TEMPS WILL CLIMB THROUGH THE 50S DURING THE DAYTIME...REMAINING COOLEST NW. DURING THE EVENING SUNDAY...RAIN WILL INCREASE IN COVERAGE AND INTENSITY AS THE MID-LEVEL TROUGH AXIS APPROACHES. AHEAD OF THE TROUGH AXIS...A SFC WARM FRONT IS PROGGED TO LIFT NORTH ACROSS OUR AREA SHORTY AFTER 00Z MONDAY. HOWEVER...WITH THE WARMEST BL AIR PROGGED TO REMAIN ACROSS THE EASTERN HALF OF THE STATE...EAST OF THE WEDGE FRONT...THE BEST INSTABILITY AND BEST CHANCE FOR CONVECTION RIGHT NOW IS EXPECTED TO REMAIN WELL EAST OF US-1. THIS BEARS CLOSE WATCHING THOUGH...AS BULK SHEAR VALUES WELL IN EXCESS OF 50KT AND FORMIDABLE LOW LEVEL HELICITY VALUES INVOF OF THE WARM FRONT WOULD PORTEND SEVERE CONVECTION IF THERE WAS ADEQUATE INSTABILITY. OTHERWISE...THE MID-LEVEL VORT AXIS LINKED TO THE AFOREMENTIONED TROUGH IS EXPECTED TO SWEEP ACROSS OUR AREA DURING THE EARLY OVERNIGHT HOURS...WITH SUBSIDENCE AND DRYING IN ITS WAKE AND THUS RAIN ENDING FROM W TO E. RAIN SHOULD BE OVER BY SUNRISE MONDAY. REGARDING TEMPS...WITH AN EVENING WARM FRONT PASSAGE...HIGH TEMPS ON SUNDAY WILL OCCUR AFTER SUNSET. TEMPS THEN STEADY IN THE UPPER 50S TO LOWER 60S...OR PERHAPS EVEN RISING A FEW DEGREES OVERNIGHT. DURING THE DAY MONDAY...THE TRAILING COLD FRONT WILL APPROACH FROM THE WEST. WITH THE BULK OF THE LINGERING MOISTURE REMAINING TO OUR EAST...LOOK FOR DRY WEATHER ACROSS CENTRAL NC ON MONDAY AND WARM PREFRONTAL TEMPS. HIGHS IN THE LOW-MID 70S. A DRY COLD FRONT PASSAGE IS EXPECTED LATE MONDAY EVENING OR AT NIGHT. THE FRONT WILL STALL ACROSS THE EASTERN CAROLINAS ON TUESDAY AS A DEEPENING UPPER TROUGH ACROSS THE MISS VALLEY GRADUALLY APPROACHES...AND SW FLOW AHEAD OF THIS TROUGH KEEPS THIS FRONT HELD UP ALONG THE COAST. AS THE AFOREMENTIONED UPPER TROUGH CONTINUES MOVING EAST...A SFC WAVE IS PROGGED TO DEVELOP ALONG THE FRONT LATE ON TUESDAY...AND MODELS HAVE RECENTLY TRENDED TOWARD A SOLUTION THAT ROTATES SOME MOISTURE AND PERHAPS SOME LIGHT COOL RAIN BACK ACROSS THE EASTERN HALF OF THE STATE TUESDAY NIGHT INTO EARLY WEDNESDAY. TEMPS TUESDAY AND WEDNESDAY...IN THE WAKE OF THE COLD FRONT...WILL BE COOLER WITH READINGS CLOSE TO...OR A FEW DEGREES BELOW NORMAL. LOOKING AHEAD TO THANKSGIVING...YET ANOTHER SHORT WAVE WILL DROP INTO THE LONGWAVE TROUGH THAT WILL BE POSITIONED ACROSS THE EAST. BOTH GFS AND ECMWF HAVE TRENDED DEEPER WITH THIS SHORT WAVE...AND EVEN SUGGEST A MID-LEVEL SHORT WAVE MAY TRY TO CLOSE OFF OVER THE MID-ATLANTIC OR CAROLINAS. WHILE THIS PATTERN MAY RAISE SOME CONCERN ...ITS WORTH NOTING THAT THIS IS 6 DAYS AWAYS AND SOLUTIONS ARE LIKELY TO CHANGE...AND SYSTEMS LIKE THIS THAT APPROACH US FROM NW IN THIS FASHION ARE OFTEN MOISTURE-LIMITED...AT LEAST ACROSS OUR AREA. WORTH WATCHING THOUGH. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
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AS OF 655 PM FRIDAY... 24-HOUR TAF PERIOD: VFR CONDITIONS WILL CONTINUE FOR THE 24 HOUR TAF PERIOD (HIGH CONFIDENCE). HIGH PRESSURE OVER THE AREA TONIGHT WILL SLOWLY SINK SOUTH AND EASTWARD THROUGH SATURDAY... YIELDING A LIGHT AND VARIABLE WIND TONIGHT... BECOMING LIGHT (~5-7 KTS OR LESS) OUT OF THE SOUTH/SOUTHWEST BY SATURDAY AFTERNOON. SKIES WILL REMAIN MOSTLY CLEAR WITH ONLY SOME HIGH THIN CIRRUS FROM TIME TO TIME. LOOKING AHEAD: ADVERSE AVIATION CONDITIONS ARE EXPECTED ON SUNDAY INTO MONDAY... AS A BAND OF PRECIP MOVES TROUGH THE AREA IN ADVANCE OF A COLD FRONT EXPECTED TO CROSS CENTRAL NC ON MONDAY EVENING INTO EARLY TUESDAY MORNING. WINDS WILL LIKELY BECOME GUSTY AS THE FRONT APPROACHES AND MOVES THROUGH THE REGION. THE FRONT WILL STALL NEAR THE COAST ON TUESDAY NIGHT INTO WEDNESDAY... WITH A WAVE OF LOW PRESSURE TRACKING ALONG IT AND POSSIBLY SENDING SOME RAIN AND SUB- VFR CONDITIONS BACK ACROSS EASTERN PORTIONS OF CENTRAL NC ON TUESDAY NIGHT INTO WEDNESDAY.
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&& .CLIMATE... RECORD LOW: GSO RDUFAY SAT 11/22 - 13 IN 1914 21 IN 2008 20 IN 2000 && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...NP NEAR TERM...KC SHORT TERM...KC LONG TERM...NP AVIATION...BSD CLIMATE...RAH

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