Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 261412 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1015 AM EDT SUN APR 26 2015 .SYNOPSIS...A STALLED FRONT WILL REMAIN JUST SOUTH OF CENTRAL NC THIS MORNING AS AN UPPER LEVEL DISTURBANCE CROSSES THE AREA. A COLD FRONT WILL SLIP SOUTH THROUGH CENTRAL NC THIS AFTERNOON AND EVENING. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM SUNDAY... MAIN ADJUSTMENT TO THE MID MORNING FORECAST UPDATE WAS TO LOWER MAX TEMPS THIS AFTERNOON A SOLID 5-8 DEGREES...BASED ON EXPECTATIONS THAT LOW OVERCAST SKIES WILL PERSIST WELL INTO THE AFTERNOON HOURS. SFC COLD FRONT HAS EXITED THE FAR SOUTHERN COUNTIES WITH A NLY LOW LEVEL FLOW IN ITS WAKE. THIS FLOW WILL CONTINUE TO FUNNEL COOL STABLE AIR INTO CENTRAL NC. 12Z GSO SOUNDING DEPICTS A FAIRLY STRONG LOW LEVEL INVERSION UP TO 850MB WITH A NEARLY SATURATED AIR MASS IN THE LOWEST 5K FT. A 850MB BOUNDARY WILL DROP SOUTHWARD ACROSS CENTRAL NC THIS AFTERNOON. NLY WINDS BEHIND THIS FEATURE WILL AID TO ADVECT A DRIER AIR MASS INTO CENTRAL NC THOUGH DISSIPATION OF THE LOW OVERCAST IN TIME TO AFFECT TEMPS IS QUESTIONABLE. BASED ON A LOW LEVEL THICKNESS SCHEME WITH SKY CHARACTER AS LOW/MID OVERCAST...SCHEME YIELDS MAX TEMPS IN THE LOW-MID 50S ACROSS THE NORTH...AND UPPER 50S/AROUND 60 SOUTH. IF BREAKS DO NOT DEVELOP IN THE FAR SOUTH-SW...TEMPS THERE MAY NOT REACH 60. A MINOR MID-UPPER LEVEL DISTURBANCE WILL CROSS THE AREA LATE THIS MORNING THROUGH EARLY AFTERNOON. THIS WILL CAUSE A BRIEF INCREASE IN PATCHY LIGHT RAIN/DRIZZLE...ESPECIALLY ACROSS THE NORTH. AFTER 2 PM...EXPECT A DECLINE IN PRECIP COVERAGE WITH THE PASSAGE OF THE 850MB TROUGH. PARTIAL CLEARING EXPECTED TO SLOWLY OCCUR NORTH-TO-SOUTH OVERNIGHT. IF SKIES CLEAR OFF ENOUGH AND SFC WINDS REMAIN LIGHT/NEAR CALM...COULD SEE AREAS OF FOG BY MORNING WITH POCKETS OF DENSE FOG POSSIBLE. MIN TEMPS 40-45 NORTH AND MID 40S SOUTH. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 335 AM SUNDAY... ANOTHER SHORTWAVE ROUNDING THE UPPER LOW OVER NOVA SCOTIA WILL CROSS NC ON MONDAY...BUT WILL ENCOUNTER A MUCH DRIER AND MORE STABLE AIRMASS...WITH PW AROUND ON HALF INCH AND A STRONG MID-LEVEL INVERSION. MODELS SUGGEST THE NORTHERN COASTAL PLAIN WOULD BE THE MOST FAVORED AREA FOR AN ISOLATED SHOWER OR SPRINKLE MONDAY AFTERNOON WITH A SHALLOW LAYER OF SATURATION NEAR 850MB. OTHERWISE...SKIES WILL BE MOSTLY SUNNY WITH AN NORTHWEST WIND AND THICKNESSES AROUND 30M BELOW NORMAL...YIELDING HIGHS ABOUT 1 DEGREES BELOW NORMAL IN THE 65-70 RANGE. LOWS MONDAY NIGHT IN THE MID 40S. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 405 AM SUNDAY... THE MODELS ARE COMING INTO BETTER AGREEMENT REGARDING THE EASTWARD- SHEARING/DEAMPLIFICATION OF AN INITIALLY CLOSED LOW OVER THE SW US AND CONCURRENT A AMPLIFICATION OF A NORTHERN STREAM SHORTWAVE TROUGH FROM NW CANADA TO THE MID-MS VALLEY...ALL ON THE WESTERN PERIPHERY OF A DEEP VORTEX OFF THE NEW ENGLAND COAST. MODEL SPREAD INCREASES THROUGH THE END OF THE WEEK...HOWEVER...AS THE MODELS CONTINUE TO HAVE A DIFFICULT TIME RESOLVING THE AMPLIFICATION OF ADDITIONAL NORTHERN STREAM SHORTWAVE ENERGY INTO AN EASTERN CONUS TROUGH...AND HOW THIS ENERGY ULTIMATELY INTERACTS WITH THE LEAD WAVES. THE MODELS ARE IN SIMILARLY GOOD AGREEMENT AT THE SURFACE REGARDING THE DEVELOPMENT OF SURFACE LOW ALONG THE GULF COAST TO NEAR SAVANNAH GA BY 00Z THU...WITH INCREASING MODEL SPREAD/DECREASING FORECAST CONFIDENCE REGARDING THE TRACK AND TIMING OF THE LOW INTO THE WESTERN ATLANTIC. WILL FOLLOW WPC PREFERENCE TOWARD A SLOWER SOLUTION ON THE WESTERN EDGE OF THE MODEL SPREAD...WITH A SUSPICION THAT THE TRAILING NORTHERN STREAM WILL HELP DRAW THE CYCLONE WEST/CLOSER TO THE COAST AS IT LIFTS UP THE MIDDLE ATLANTIC COAST THROUGH THU. THE SENSIBLE WEATHER AFFECTS WILL BE A WARM AND DRY TUE...WITH TEMPERATURES IN THE MIDDLE 60S TO AROUND 70 DEGREES...FOLLOWED BY RAIN DEVELOPING/SPREADING NORTHEAST INTO CENTRAL NC LATE TUE NIGHT OVER THE SOUTHERN PIEDMONT AND ACROSS THE REMAINDER OF THE CWFA THROUGH THE DAY WED. EVEN PRIOR TO THE ONSET OF RAIN WED...MID LEVEL OVERCAST SHOULD CAUSE TEMPERATURES TO REMAIN BELOW GUIDANCE - IN THE UPPER 50S TO LOWER 60S...WARMEST NE; AND EVEN THOSE TEMPERATURES MAY ULTIMATELY PROVE A CATEGORY TOO WARM IF THE OVERCAST AND RAIN INDEED MATERIALIZE AS EXPECTED. RAIN WOULD THEN TAPER OFF FROM WEST TO EAST WED NIGHT-THU...AND YIELD TO DRIER AND WARMER CONDITIONS FRI- SAT...WITH TEMPERATURES RETURNING TO NEAR AVERAGE LEVELS IN THE MIDDLE 70S TO AROUND 80 DEGREES BY SAT. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... AS OF 700 AM SUNDAY... AN UPPER LEVEL DISTURBANCE CROSSING THE AREA THIS MORNING WILL DEPART TO THE EAST...BRINGING AN END TO MOST OF THE LINGERING SHOWERS ACTIVITY OVER CENTRAL NC. WHAT SHOWERS THAT DO REMAIN SHOULD BE MOSTLY CONFINED TO AN AREA FROM KRDU TO KRWI AND SOUTH TO KFAY...WITH SOME ADDITIONAL SHOWERS POSSIBLE THIS AFTERNOON SOUTH OF KFAY. MEANWHILE...IFR AND LIFR CEILINGS/VSBYS WILL PERSIST THROUGH MIDDAY...WITH IMPROVEMENT TO MVFR THIS AFTERNOON AS DRIER AIR FILTERS INTO THE AREA FROM THE NORTH. CONFIDENCE IN THE TIMING OF MVFR...AND EVENTUALLY VFR CONDITIONS....IT LOW AT THE MOMENT. HOWEVER...GUIDANCE SUGGESTS MVFR WILL BE POSSIBLE AT MOST SITES BY 18-20Z AND VFR BY 00-03Z. WINDS WILL BE RELATIVELY LIGHT AND OUT OF THE NORTH-NORTHEAST THROUGH THE PERIOD. OUTLOOK...IMPROVING CONDITIONS WILL CONTINUE MONDAY MORNING...WITH VFR CONDITIONS EXPECTED MONDAY AND TUESDAY. A LOW PRESSURE SYSTEM APPROACHING FROM THE SW WILL BRING THE NEXT CHANCE FOR SUB VFR CONDITIONS TO CENTRAL NC WEDNESDAY INTO THURSDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...22 NEAR TERM...WSS SHORT TERM...22 LONG TERM...RAH AVIATION...22

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