Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 190658 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 255 AM EDT SAT APR 19 2014 .SYNOPSIS...
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LOW PRESSURE OVER THE NORTHEASTERN GULF OF MEXICO THIS MORNING WILL DRIFT VERY SLOWLY ALONG THE SOUTHEAST US COAST THROUGH THE WEEKEND.
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&& .NEAR TERM /THROUGH SATURDAY/... AS OF 930 PM FRIDAY... RAIN STARTING TO SET IN ACROSS THE FORECAST AREA WITH NORTHWARD EXPANSION OF PRECIP SHIELD AHEAD OF THE AMPLIFYING CLOSED UPPER LOW OVER THE NORTHERN CENTRAL GULF...WITHIN THE FAVORABLE UPPER DIFFLUENT REGION. THIS NORTHWARD EXPANSION IS LITTLE FASTER THAN WHAT PREVIOUS GUIDANCE SHOWN AND THUS HAVE INCREASED POPS ACCORDINGLY WITH CATEGORICAL POPS EVERYWHERE BY 06Z AS LOW AND MID- LEVEL FGEN REALLY RAMPS UP ON COOL SIDE OF THE SHARPENING COASTAL FRONT AND STILL DEVELOPING AREA OF LOW PRESSURE OVER THE NORTHEASTERN GULF...WITH STRONG INFLUX OF ATLANTIC MOISTURE CONTINUING THROUGH SATURDAY MORNING AS PWATS INCREASE TO 1.2-1.4". EXPECT HEAVIEST RAINFALL ACROSS THE SOUTH/SOUTHEAST...RANGING FROM A ONE-THIRD OF AN INCH ACROSS THE NW PIEDMONT TO 1.25-1.5" ACROSS THE SANDHILLS/COASTAL PLAIN. LOWS TONIGHT 45-50.-CBL SATURDAY IS EXPECTED TO BE RAW AND CHILLY WITH PERIODS OF RAIN AND A STEADY NE FLOW AT 15-20 MPH WITH GUSTS TO 25 MPH. GIVEN THE STRENGTH AND POSITION OF THE HIGH FORECAST TO THE NORTH... AND THE EXPECTED WIDESPREAD RAIN AND LOW CLOUDINESS SATURDAY... THE THOUGHT IS TO UNDERCUT MOS GUIDANCE NUMBERS BACK TO A FEW DEGREES OF THE FORECAST WET BULB TEMPERATURES. THIS WOULD YIELD READINGS THAT SHOULD STRUGGLE TO REACH 50 IN THE NORTH... AND 50S ELSEWHERE SATURDAY. A GOOD 20-25 DEGREES BELOW NORMAL (SOUND FAMILIAR??). && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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AS OF 255 AM SATURDAY... THE SLOW MOVING CUT OFF LOW IMPACTING THE REGION THIS WEEKEND IS FORECAST TO BE EAST OF THE CAROLINAS SUNDAY NIGHT...WITH AN ELONGATED SURFACE RIDGE EXTENDING FROM THE MID-ATLANTIC STATES INTO THE NC. AS THE LOW MOVES OFF TO THE NORTHEAST...WINDS SHOULD BACK AROUND TO MORE NORTHERLY THAN NORTHEASTERLY AND ALLOW SOME DRIER AIR TO WORK INTO CENTRAL NC FROM THE NORTH. THE NAM ISNT QUITE AS DRY AS THE GFS AND ECMWF...SHOWING SOME MOISTURE LINGERING AROUND 850MB EAST OF I-95. WHILE THE AIRMASS WONT BEGIN TO MODERATE SIGNIFICANTLY UNTIL TUESDAY...STRONGER HEATING SHOULD SUPPORT HIGHS REACHING THEIR POTENTIAL OF UPPER 60S AND LOWER 70S. A PROGRESSIVE TROUGH MOVING THROUGH THE CENTRAL US WILL APPROACH THE REGION MONDAY NIGHT AND EARLY TUESDAY...WITH THE ASSOCIATED FRONTAL ZONE PROJECTED TO CROSS CENTRAL NC TUESDAY AFTERNOON AND EVENING. AHEAD OF THE SYSTEM...LOWS WILL BE MUCH MORE MILD MONDAY NIGHT WITH INCREASING MID/HIGH CLOUDS AND A WEAK RETURN FLOW ACROSS THE WESTERN PIEDMONT. LOWS IN THE LOWER 50S WEST AND UPPER 40S EAST. SOUTH TO SOUTHWESTERLY FLOW WILL INCREASE ON TUESDAY AHEAD OF THE APPROACHING FRONT. MODELS CURRENTLY FORECAST A DEWPOINT RECOVERY INTO THE MID AND UPPER 50S...WHICH COMBINED WITH HIGHS IN THE UPPER 70S TO AROUND 80 AND WEAK MID-LEVEL LAPSE RATES WOULD SUGGEST WEAK INSTABILITY...MAINLY ACROSS THE WEST. MODEST SHEAR MAY SUPPORT A FEW STRONG STORMS...BUT WITHOUT BETTER UPPER SUPPORT THE THREAT OF SEVERE WEATHER LOOKS ISOLATED AT THIS POINT.
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&& .LONG TERM /WEDNESDAY THROUGH FRIDAY/...
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AS OF 255 AM SATURDAY... BEHIND TUESDAYS SYSTEM...CANADIAN HIGH PRESSURE WILL BUILD ACROSS MUCH OF THE EASTERN US ON WEDNESDAY AND THURSDAY. THURSDAY LOOKS TO BE THE COOLEST DAY AS THICKNESSES FALL BACK BELOW NORMAL...WITH HIGHS MAYBE 5-10 DEGREES BELOW NORMAL...BUT THEN QUICKLY REBOUND ON FRIDAY AS ANOTHER PROGRESSIVE UPPER TROUGH APPROACHES FROM THE WEST. THIS NEXT SYSTEM RESEMBLES THE EARLY WEAK SYSTEM...THOUGH POTENTIALLY WITH A LITTLE MORE MOISTURE AVAILABLE FROM THE GULF. THE CURRENT FORECAST WILL REMAIN DRY...WITH THE BETTER CHANCE OF PRECIP JUST BEYOND THE END OF THE FORECAST ON FRIDAY NIGHT AND SATURDAY.
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&& .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 145 AM SATURDAY... AN EXPANSIVE STORM SYSTEM CENTERED ON THE FL GULF COAST WILL AFFECT THE SOUTHEAST STATES AND CAROLINAS THROUGHOUT TODAY AND TONIGHT. CURRENTLY... DESPITE FAIRLY WIDESPREAD LIGHT RAIN... WITH THE EXCEPTION OF FAY... VFR CONDITIONS DOMINATE WITH MOST VSBYS AOA 6SM AND CIGS AOA 4 000 FT... WHILE FAY HAS SEEN A BAND OF HEAVIER RAIN BRINGING IN IFR CIGS AND MVFR VSBYS. THESE IFR CIGS ARE LIKELY TO CONTINUE TO ADVECT INTO FAY THROUGH 12Z... AND MAY CREEP INTO THE VICINITY OF RWI. AT INT/GSO/RDU... VFR CIGS AND VSBYS ARE EXPECTED TO PREVAIL THROUGH 12Z... ALTHOUGH VSBYS MAY BRIEFLY DROP TO MVFR IN ANY HEAVIER RAIN BANDS. AFTER 12Z... RDU/RWI SHOULD FALL TO MAINLY MVFR... LASTING UNTIL AROUND 19-21Z... WITH BRIEF IFR CIGS POSSIBLE BETWEEN 12Z AND 16Z. INT/GSO SHOULD REMAIN VFR... ALTHOUGH A BRIEF DROP TO MVFR 12Z-16Z THIS MORNING IS POSSIBLE. FAY IS LIKELY TO EXPERIENCE THE WORST AVIATION CONDITIONS WITH IFR CONDITIONS HOLDING THROUGH 06Z TONIGHT. AT INT/GSO/RWI/RDU... CIGS ARE EXPECTED TO IMPROVE TO VFR AFTER 21Z AS DRIER LOW LEVEL AIR NOSES IN FROM HIGH PRESSURE TO THE NORTH... WITH JUST PATCHY DRIZZLE AT MOST FROM 21Z THROUGH THE END OF THE TAF VALID PERIOD (06Z SUN). LOOKING BEYOND 06Z SUN... EXPECT IMPROVEMENT TO MVFR AT FAY 06Z-09Z THEN TO VFR BY 12Z... AND MAINLY VFR CIGS AT ALL OTHER SITES THROUGH SUNDAY. EXPECT VFR CONDITIONS TO DOMINATE THROUGH MON NIGHT. PASSAGE OF A MID LEVEL TROUGH AND SURFACE COLD FRONT FROM THE NW WILL BRING A RISK OF SUB-VFR CONDITIONS TUE/TUE NIGHT. VFR CONDITIONS RETURN FOR WED. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...SMITH NEAR TERM...CBL/BADGETT SHORT TERM...SMITH LONG TERM...SMITH AVIATION...HARTFIELD

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