Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 061824 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 224 PM EDT FRI MAY 6 2016 .SYNOPSIS... AN UPPER LEVEL LOW CENTERED OVER THE MID-ATLANTIC AND CAROLINAS THIS AFTERNOON WILL GRADUALLY SHIFT OFFSHORE TONIGHT AND SATURDAY. WESTERLY FLOW ALOFT WILL DEVELOP LATE THIS WEEKEND...WITH SOUTHWEST FLOW ALOFT PREVAILING EARLY NEXT WEEK. && .NEAR TERM /TODAY AND TONIGHT/...
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AS OF 200 PM FRIDAY... A BROAD UPPER LEVEL LOW WILL REMAIN IN PLACE OVER THE MID-ATLANTIC AND CAROLINAS THROUGH TONIGHT. THE STRONGEST DPVA /SHORTWAVE ENERGY/ ROTATING AROUND THE CORE OF THE UPPER LOW WILL REMAIN WELL NORTH OF CENTRAL NC (ACROSS THE DELMARVA AND NORTHERN MID-ATLANTIC) THROUGH TONIGHT...RESULTING IN BROADER/WEAKER UPPER LEVEL FORCING THIS AFTERNOON (IN COMPARISON TO YESTERDAY)...PRIMARILY IN THE FORM OF CYCLONIC SHEAR/CURVATURE VORTICITY. DESPITE MARGINAL SFC MOISTURE WITH DEWPOINTS IN THE UPPER 40S TO LOWER 50S...STEEP MID-LEVEL LAPSE RATES /COOL TEMPS ALOFT/ AND INSOLATION SHOULD BE SUFFICIENT FOR MARGINAL/SHALLOW DESTABILIZATION THIS AFTERNOON...ON THE ORDER OF 100-250 J/KG...WITH EFFECTIVE EQUIL. LEVELS ~10-15 KFT GIVEN THAT THE BULK OF POSITIVE ENERGY WILL BE AT/BELOW THE 700 MB LEVEL. WITH THE ABOVE IN MIND...EXPECT SCATTERED LOW-TOPPED SHOWERS THROUGH THIS AFTERNOON...PRIMARILY ALONG/EAST OF HWY 1 (IN CLOSER PROXIMITY TO THE SFC-H85 TROUGH ALONG THE NC COAST) WHERE LOW-LEVEL MOISTURE IS GREATER. DO NOT ANTICIPATE ANY POTENTIAL FOR THUNDER THIS AFTERNOON GIVEN WEAKER UPPER LEVEL FORCING AND THAT THE BULK OF POSITIVE ENERGY /CAPE/ IS LOCATED BENEATH THE -10 TO -20C ISOTHERM LEVELS. EXPECT ISOLD/SCT SHOWERS TO WANE IN COVERAGE WITH LOSS OF HEATING THIS EVENING. HIGHS TODAY UPPER 50S TO LOWER 60S FAR N/NE TO UPPER 60S /NEAR 70F/ IN THE FAR SW PIEDMONT. LOWS TONIGHT IN THE UPPER 40S TO LOWER 50S. -VINCENT
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&& .SHORT TERM /SATURDAY AND SATURDAY NIGHT/...
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AS OF 200 PM FRIDAY... THE UPPER LEVEL LOW WILL FINALLY SHIFT OFFSHORE THE MID-ATLANTIC/ CAROLINA COAST IN THIS PERIOD...SUPPLANTED BY A MUCH WARMER NORTHWEST (SAT) TO WESTERLY (SAT NIGHT) FLOW ALOFT. MODEL GUIDANCE INDICATES A SMALL POTENTIAL FOR VERY LIGHT RAIN CANNOT BE ENTIRELY RULED OUT IN THE N/NW PIEDMONT SAT AFT/EVE IN ASSOCIATION WITH LOW- LEVEL WARM ADVECTION FROM THE WEST AND (PERHAPS) WEAK DPVA ATTENDANT SMALL AMPLITUDE WAVES EMBEDDED WITHIN NW/WNW FLOW ALOFT. THOUGH PROBABILITIES ARE LOW...WILL INDICATE A SLIGHT CHANCE OF RAIN IN LATE SAT AFT/EVE IN THE AFOREMENTIONED LOCATIONS. OTHERWISE...EXPECT DRY CONDITIONS TO PREVAIL THROUGH SAT NIGHT. HIGHS WILL REBOUND INTO THE MID 70S VIA WARM ADVECTION/INSOLATION SAT AFTERNOON...AND LOWS SAT NIGHT WILL BOTTOM OUT IN THE LOWER 60S. -VINCENT
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 300 AM FRIDAY... A COLD FRONT WILL CROSS THE AREA EARLY SUNDAY...BUT HOW FAR SOUTH INTO NC THE FRONT MAKES IT REMAINS TO BE SEEN WITH THE GFS PUSHING THE COOL AIR A LITTLE FURTHER SOUTH. IN THE WAKE OF THE FRONT...HIGH PRESSURE BUILDING IN OVER FLORIDA SHOULD HELP TO BUMP UP TEMPERATURES...ESPECIALLY IN THE SOUTHERN COUNTIES WHERE MID 80S WILL BE PROBABLE HIGHS WITH CLOSER TO 80 ACROSS THE NORTH. ALOFT...NORTHWESTERLY FLOW WILL GUIDE A FEW SMALL DISTURBANCES ACROSS THE AREA DURING THE DAY BUT ANY PRECIPITATION SHOULD BE LIGHT AND FLEETING. STILL WILL CARRY SLIGHT CHANCES ACROSS MUCH OF THE CWA SUNDAY AFTERNOON. LOWS SUNDAY NIGHT IN THE MID 50S TO NEAR 60 DEGREES. MONDAY AND MONDAY NIGHT...DETERMINISTIC MODELS ARE STILL IN FAIRLY GOOD AGREEMENT ABOUT THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE CENTRAL PLAINS WITH A WARM FRONT HOVERING NORTH OF NC ON MONDAY AS SURFACE HIGH PRESSURE CAMPS OUT OVER THE WESTERN ATLANTIC. THIS SHOULD KEEP CONDITIONS DRY AND WARM WITH HIGHS IN THE LOW TO MID 80S AND LOWS MONDAY NIGHT IN THE LOW TO MIDDLE 60S. CONFIDENCE IN THE FORECAST BEGINS TO BREAK DOWN ON TUESDAY AS MODELS ARE IN DISARRAY OVER THE HANDLING OF THE NORTHERN STREAM SYSTEM AS THE GFS DEVELOPS AN UPPER LEVEL LOW THAT MAINTAINS THE CENTRAL PLAINS SURFACE LOW. THIS FEATURE DOES NOT EXIST IN THE ECMWF AND THE SURFACE LOW DEGRADES AND IS CARRIED OFF TO THE EAST. A BLEND OF THE MODELS WOULD SUGGEST NOT TOO MUCH PRECIPITATION ACROSS CENTRAL NC IF ANY AND CONTINUED WARM TEMPERATURES. BEST CHANCES WOULD BE ACROSS THE NORTH WITH THE POTENTIAL FOR A THUNDERSTORM IF CONVECTION DOES OCCUR. WEDNESDAY ONWARD...A BLEND OF THE ENSEMBLES IS THE MORE FAVORED SOLUTION WHICH WILL GENERALLY INCREASE POPS ON WEDNESDAY WITH CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE AFTERNOON. EXTREME DIFFERENCES IN THE MODELS ON THURSDAY CAUSE EVEN A BLEND OF THE MODELS TO BE MEANINGLESS AT THIS POINT. THEREFORE WILL CONTINUE SLIGHT CHANCE/CHANCE POPS THROUGH THURSDAY BUT WITH NO REAL CONFIDENCE. LOW TO MID 80S THROUGH THE REST OF THE PERIOD WITH LOWS IN THE MID 60S. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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AS OF 100 PM FRIDAY... 24-HR TAF PERIOD: MVFR (PERHAPS OCCASIONAL IFR) CEILINGS AN SCATTERED SHOWERS WILL REMAIN POSSIBLE AT EASTERN TERMINALS (RDU/FAY/RWI) THROUGH SUNSET THIS EVENING. ELSEWHERE...VFR CEILING SAT 4-6 KFT AGL WILL PREVAIL WITH A W/NW WIND AT 10-15 KT AND OCCASIONAL HIGHER GUSTS. VFR CONDITIONS ARE EXPECTED TO PREVAIL EVERYWHERE TONIGHT/SAT IN AS A WARMER/DRIER AIRMASS ADVECTS INTO THE REGION FROM THE WEST. LOOKING AHEAD: VFR CONDITIONS ARE EXPECTED TO PREDOMINATE THROUGH EARLY/MID NEXT WEEK...WITH THE BEST POTENTIAL FOR WIDESPREAD ADVERSE AVIATION CONDITIONS HOLDING OFF UNTIL LATE NEXT WEEK. -VINCENT
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...VINCENT LONG TERM...ELLIS AVIATION...VINCENT

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