Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 031832 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 230 PM EDT SUN MAY 3 2015 .SYNOPSIS...
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WEAK HIGH PRESSURE OVER THE AREA WILL MOVE OFF THE COAST ON MONDAY...WITH SOUTHERLY RETURN FLOW BRINGING ABOVE NORMAL TEMPERATURES FOR THE UPCOMING WORK WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AS OF 230 PM SUNDAY... HIGH PRESSURE AT THE SURFACE WILL CONTINUE TO SHIFT EAST AND OFFSHORE TONIGHT...WHILE THE MID-LEVEL RIDGE AXIS SETS UP OVERHEAD. ALOFT...A DISTURBANCE OVER SOUTHERN ILLINOIS THIS AFTERNOON WILL DRIFT SOUTHEAST TONIGHT AND CROSS THE AREA EARLY MONDAY. POOR DIURNAL TIMING AND LIMITED MOISTURE/STRONG CAPPING SHOULD RENDER THIS DISTURBANCE PRECIP FREE AND ONLY BRING SOME THIN HIGH CLOUDS. MODELS SHOW MORE SUBSTANTIAL MOISTURE POOLING ALONG THE MOUNTAINS AND WITHIN THE 700MB ANTICYCLONE OVER WESTERN NC...AN THAT MOISTURE (AROUND 7-10K FT)...SHOULD SLIDE SLOWLY EAST INTO THE PIEDMONT LATE TONIGHT. LOWS WILL MAINLY BE IN THE LOW/MID 50S...SLIGHTLY COOLER EAST WHERE WINDS SHOULD GENERALLY BE LIGHTEST.
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&& .SHORT TERM /MONDAY AND MONDAY NIGHT/...
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AS OF 230 PM SUNDAY... HIGH PRESSURE WILL SET UP OFFSHORE MONDAY WITH A RIDGE AXIS STRETCHING ACROSS THE STATE. THE MOISTURE RETURN AROUND THE HIGH IS PRETTY LIMITED AND MOST OF CENTRAL NC WILL STAY WELL CAPPED AS DEWPOINTS AGAIN MIX OUT INTO THE UPPER 40S. THE WEAK DISTURBANCE ALOFT (MENTIONED ABOVE) LOOKS TO HAVE LITTLE IMPACT GIVEN THE STABILITY AS DRIFTS EAST TOWARD THE COAST MONDAY AFTERNOON. INSTEAD...THE ONLY CHANCE OF PRECIP...AND A VERY SLIGHT CHANCE AT THAT...MAY COME FROM SOME DIURNALLY DRIVEN SHOWERS OVER THE HIGHER TERRAIN DRIFTING EAST TOWARD THE NORTHWEST PIEDMONT LATER IN THE AFTERNOON. 850MB TEMPS WILL BE COMPARABLE TO TODAY...AROUND 10C...AND WHILE MIXING ISN`T AS DEEP IT SHOULD EXTEND THROUGH 850MB...SUGGESTING HIGHS SIMILAR TO TODAY...78-81. LOWS MONDAY NIGHT INTO THE MID 50S.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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AS OF 230 PM SUNDAY... FOR THE PERIOD TUESDAY THROUGH WEDNESDAY...BOTH THE NAM AND THE GFS FORECAST LIMITED OVERALL LIFT WITH RIDGING OVERHEAD. A SURFACE FRONT APPROACHES FROM THE NORTH LATE WEDNESDAY...WITH THE NAM A LITTLE FARTHER SOUTH COMPARED TO THE GFS AND WITH BOTH MODELS APPARENTLY KEEPING THE BOUNDARY NORTH OF CENTRAL NORTH CAROLINA AT LEAST THROUGH THE DAY WEDNESDAY. WINDS ARE GENERALLY LIGHT SURFACE THROUGH 500MB...AND EVEN THROUGH 300MB SAVE FOR THE GFS FORECAST OF A MODEST INCREASE IN 300MB WINDS FROM THE EAST LATE WEDNESDAY. WITH FORCING EXPECTED TO LIE AWAY FROM CENTRAL NORTH CAROLINA...CHANCES FOR ANY SHOWER OR THUNDERSTORM WILL BE PREDICATED ON WHERE ANY WOULD DEVELOP AND MOVE INTO CENTRAL NORTH CAROLINA. ON TUESDAY...BUFR SOUNDINGS FROM THE GFS AND NAM ARE CAPPED ACROSS MUCH IF NOT ALL OF CENTRAL NORTH CAROLINA. THE BEST 850MB THETA-E AIR IS NORTHWEST OF CENTRAL NORTH CAROLINA...TOWARD THE MOUNTAINS AND FOOTHILLS...WHERE THE 0-3KM MUCAPE IS FORECAST TO BE TO NEAR 1500J/KG. BASED ON THE THICKNESS FORECAST...A SHOWER OR STORM COULD MOVE OFF THE HIGHER TERRAIN TOWARD THE FAR NORTHWEST PIEDMONT LATE IN THE DAY...AND WILL FORECAST A SLIGHT CHANCE OF A THUNDERSTORM LATE TUESDAY AFTERNOON AND EARLY TUESDAY EVENING MAINLY OVER FORSYTH COUNTY...AS EVEN THE KGSO BUFR SOUNDING IS CAPPED THROUGH 00Z WEDNESDAY BUT NAM AND GFS QPF EEK A VERY MINOR AMOUNT INTO THE KINT AREA LATE IN THE DAY. ON WEDNESDAY...MUCAPE IN THAT 0-3KM LAYER INCREASES OVER THE HIGHER TERRAIN AND NEAR THE SURFACE BOUNDARY TO 2000-2500J/KG...WHERE THE HIGHER 850MB THETA-E AIR SHOULD BE. BUFR SOUNDINGS AGAIN ARE LARGELY CAPPED...ALTHOUGH EVEN ON THE LESS UNSTABLE GFS THERE IS FORECAST MODEST MID-LEVEL COOLING ON THE KGSO BUFR SOUNDING LATE IN THE DAY. 850MB CONVERGENCE IS NEGLIGIBLE AND CENTRAL NORTH CAROLINA REMAINS UNDER UPPER CONVERGENCE...BUT IT IS POSSIBLE AN ISOLATED THUNDERSTORM MOVES OFF OF THE HIGHER TERRAIN OR AWAY FROM THE SURFACE FRONT AND FOLLOWS THE THICKNESSES SOUTH. WILL HAVE A SLIGHT CHANCE OF A THUNDERSTORM WEDNESDAY AFTERNOON AND EARLY EVENING PRIMARILY IN THE INTERSTATE 85 CORRIDOR...WHICH IS CLOSE TO THE CONSENSUS OF THE SOUTHERN EXTENT OF MEASURABLE QPF BETWEEN THE GFS AND NAM FOR WEDNESDAY AFTERNOON AND JUST SOUTH OF THE FORECAST 850MB LIFT. HIGHS 80 TO 85 WITH THE AVERAGE A DEGREE OR TWO HIGHER WEDNESDAY WITH HIGHER 1000-850MB THICKNESSES. LOWS TUESDAY NIGHT IN THE 50S. FOR THE PERIOD WEDNESDAY NIGHT THROUGH SUNDAY...FAIR UNCERTAINTY CONTINUES REGARDING THE DEVELOPMENT OF SURFACE LOW PRESSURE OFFSHORE OF THE SOUTHEAST CONUS IN WEAK...BROAD LOW PRESSURE ALOFT. FOR THE MOST PART...THE LONG-TERM GUIDANCE HAS BEEN CONSISTENT WITH THEMSELVES. THE GFS HAS GENERALLY BEEN FARTHER SOUTH WITH ANY LOW PRESSURE TRACK GIVEN STRONGER SURFACE HIGH PRESSURE TO THE NORTH... WHILE THE ECMWF HAS GENERALLY WEAKENED THE SURFACE HIGH SUFFICIENTLY THAT SURFACE LOW PRESSURE IS ABLE TO MOVE FARTHER NORTH. COARSE MODEL SOUNDINGS SHOW DIFFERENCES IN MOISTURE AND THE AVAILABLE CAP DEPENDING ON THE DAY...BUT WHAT BOTH THE GFS AND ECMWF SEEM TO HAVE IN COMMON ARE LIMITED INSTABILITY IN GENERAL...LIMITED LOW-LEVEL CONVERGENCE AWAY FROM ANY SURFACE LOW PRESSURE...AND RELATIVELY WEAK WINDS ALOFT. FOR THIS FORECAST...CONSIDERING WHAT THE LONG-TERM GUIDANCE HAS IN COMMON...DO NOT HAVE CONFIDENCE TO GO BEYOND A SLIGHT CHANCE OR ISOLATED SHOWERS AND THUNDERSTORMS. FOR THURSDAY... FOCUSED THE SLIGHT CHANCE MAINLY TOWARD THE NORTHWEST PIEDMONT CLOSER TO THE SURFACE BOUNDARY AND A LITTLE BETTER INSTABILITY GIVEN A CONSENSUS APPROACH TO THE LONG-TERM GUIDANCE...AND FOR FRIDAY HAVE MORE OF A FOCUS FOR THE SLIGHT CHANCE OVER THE FAR NORTHWEST PIEDMONT AND THE COASTAL PLAIN...THE LATTER DUE TO A CONSENSUS INCREASE IN THE MEAN MOISTURE. SLIGHT CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGHOUT CENTRAL NORTH CAROLINA SATURDAY AND SUNDAY DUE TO UNCERTAINTY...LEANING TOWARD CLIMATOLOGY AND...FOR SATURDAY...WHERE 00Z GFS ENSEMBLES SHOW HIGHER POPS. HIGHS IN THE NORMAL RANGE TO A CATEGORY OR TWO ABOVE...MOSTLY AROUND 80 EXCEPT 80 TO 85 SUNDAY WHEN 1000-850MB THICKNESSES ARE FORECAST HIGHEST. LOWS UPPER 50S TO MID 60S.
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&& .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...22 NEAR TERM...22 SHORT TERM...22 LONG TERM...DJF AVIATION...22

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