Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 170659 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 259 AM EDT THU APR 17 2014 .SYNOPSIS...UNSEASONABLY STRONG...POLAR HIGH PRESSURE WILL BUILD SOUTH FROM NEW ENGLAND TODAY...THEN LINGER THROUGH FRIDAY. MEANWHILE...LOW PRESSURE WILL DEVELOP OVER THE NORTHEASTERN GULF OF MEXICO FRIDAY...THEN MEANDER ALONG THE SOUTHEAST US COAST THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/...
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AS OF 300 AM THURSDAY... UNSEASONABLY STRONG/1040-1045 MB POLAR HIGH PRESSURE CENTERED OVER MAINE WILL RIDGE SOUTH AND MAINTAIN CONTINUED COOL...BUT INCREASINGLY MODIFIED...NORTHEASTERLY FLOW TODAY. A SOUTHERN STREAM WAVE ALOFT AND ASSOCIATED CIRRUS OVER AL/GA WILL LIFT NORTHEASTWARD ACROSS CENTRAL NC DURING THE MIDDAY-EARLY AFTERNOON HOURS. BUFR FORECAST SOUNDINGS HAVE TRENDED LESS AGGRESSIVE WITH THE WESTWARD EXPANSION OF ATLANTIC MOISTURE BENEATH THE ~4000 FT SUBSIDENCE INVERSION EVIDENT ON REGIONAL RAOBS FROM WED. HOWEVER...EARLY MORNING SATELLITE IMAGERY INDICATES A FEW PATCHES OF STRATOCUMULUS HAVE SPREAD INLAND OVER NE SC AND SE NC THIS MORNING...SO SOME OF THIS MOISTURE - TRAPPED BENEATH THE INVERSION ABOVE - IS APT TO AFFECT AT LEAST COASTAL PLAIN COUNTIES FROM MID-MORNING TO EARLY AFTERNOON. DRY ADIABATIC MIXING THROUGH 900 MB...AND ABOUT A 20-25 METER INCREASE IN FORECAST LOW LEVEL THICKNESSES OVER THOSE OF WED...SUPPORT HIGHS MAINLY BETWEEN 60 AND 65 DEGREES. TONIGHT: CHILLY WITH GOOD RADIATIONAL COOLING...PARTICULARLY WITH MAINLY CLEAR SKIES THROUGH MIDNIGHT...FOLLOWED BY THE ARRIVAL OF ADDITIONAL CIRRUS DOWNSTREAM OF ANOTHER SOUTHERN STREAM SHORTWAVE TROUGH OVER NM THIS MORNING. LOWS GENERALLY IN THE MIDDLE TO UPPER 30S. PATCHY FROST WILL CONSEQUENTLY BE POSSIBLE...PARTICULARLY IN RURAL PIEDMONT LOCATIONS.
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&& .SHORT TERM /FRIDAY /...
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AS OF 330 PM WEDNESDAY... SHOULD SEE AT A MINIMUM A MIXTURE OF SUN AND CLOUDS FRIDAY WITH THE CHARACTER OF THE SKY BECOMING MOSTLY CLOUDY OR OVERCAST BY FRIDAY AFTERNOON. ISENTROPIC UPGLIDE DOES NOT APPEAR STRONG ENOUGH TO SUPPORT PRECIP FRIDAY AFTERNOON...ASIDE FROM A STRAY SHOWER ACROSS THE FAR SE. AIR MASS WILL CONTINUE TO GRADUALLY MODIFY BUT AFTERNOON TEMPS WILL REMAIN WELL BELOW NORMAL. MAX TEMPS 60-65.
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&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... AS OF 3 PM WEDNESDAY... FRIDAY NIGHT THROUGH SUNDAY NIGHT: THE WEEKEND FORECAST CONTINUES TO HAVE SOME UNCERTAINTY WITH REGARD TO THE EVOLUTION OF A POSSIBLE CLOSED LOW LINGERING ACROSS THE SOUTHEASTERN U.S/OFFSHORE. WHILE THE NORTHERN STREAM ENERGY IS PROGRESSIVE AND PUSHES EASTWARD FRIDAY NIGHT INTO SATURDAY. IN ADVANCE OF THE NORTHERN STREAM TROUGH BOTH THE 12Z GFS AND ECMWF PULLS MOISTURE NORTHWARD... AND PRODUCED SOME LIGHT RAIN ACROSS OUR FAR SOUTHEAST/EAST ON FRIDAY NIGHT INTO EARLY SATURDAY MORNING... WITH THE BULK OF THE PRECIP EXPECTED TO BE TO OUR EAST AND SOUTH. HOWEVER... MODEL GUIDANCES IS STRUGGLING WITH WHAT WILL HAPPEN WITH THE LINGERING SOUTHERN STEAM ENERGY THAT POSSIBLY CLOSES OFF INTO A CLOSED LOW AND LINGERS NEAR FL AND OFF THE SOUTHEAST U.S. COAST. THE 12Z ECMWF HAS COME A MORE IN THE LINE WITH THE 12Z GFS IN SHOWING LINGERING MID LEVEL ENERGY SLOWLY SHIFTING EASTWARD AND FAR ENOUGH AWAY FROM THE COAST TO KEEP US DRY SATURDAY AFTERNOON THROUGH THE REST OF THE WEEKEND. HOWEVER... GUIDANCES HAS SHOWN POOR RUN TO RUN CONTINUITY. THUS... CONFIDENCE IS NOT HIGH THAT LATE SATURDAY INTO SUNDAY THAT WE WILL BE COMPLETELY DRY AT THIS TIME ACROSS OUR ENTIRE AREA (IF PRECIP LINGER... LOCATIONS ACROSS THE EAST/SOUTHEAST WOULD SEE THE BEST CHANCE/MOST). FOR NOW WILL GO WITH A DRY FORECAST AS MENTIONED ABOVE FROM SATURDAY AFTERNOON ONWARD. WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA FROM THE NORTH AND A COOL EAST TO NORTHEASTERLY LOW LEVEL FLOW EXPECT HIGH TEMPS WILL REMAIN SLIGHTLY BELOW NORMAL WITH AT LEAST SOME CLOUD COVER (MORE EAST VS WEST). THUS... WILL GO WITH HIGH TEMPS THIS WEEKEND IN THE UPPER 60S TO LOWER 70S... WITH LOW TEMPS IN THE 40S TO LOWER 50S. MONDAY THROUGH WEDNESDAY: NEXT MID LEVEL DISTURBANCE IS EXPECTED TO CROSS THE REGION ON TUESDAY... ALONG WITH A WEAK SURFACE TROUGH. HOWEVER... WITH LACK OF ANY SIGNIFICANT MOISTURE RETURN WILL KEEP POPS LOW AT THIS TIME. TEMPS EARLY TO MID NEXT WEEK ARE EXPECT TO WARM AGAIN... WITH HIGHS IN THE 70S AND LOWS IN THE 50S. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... AS OF 200 AM THURSDAY... UNSEASONABLY STRONG/POLAR HIGH PRESSURE WILL RIDGE SOUTH FROM NEW ENGLAND AND RESULT IN CLEAR/VFR CONDITIONS THIS MORNING...WHICH WILL YIELD TO BOTH INCREASING CIRRUS IN SW FLOW ALOFT FROM THE WEST...AND A BRIEF PERIOD OF SCT TO PERHAPS EVEN BKN STRATOCUMULUS BETWEEN 2500- 4000 FT MAINLY AT EASTERN TERMINALS BETWEEN MID-MORNING THROUGH EARLY AFTERNOON. THE SURFACE RIDGE WILL ALSO MAINTAIN A NORTHEASTERLY SURFACE WIND OVER CENTRAL NC...STRONGEST AND OCCASIONALLY GUSTY INTO THE UPPER TEENS KTS AT EASTERN TERMINALS... ALSO FROM MID-MORNING TO EARLY AFTERNOON. OUTLOOK: A LOW PRESSURE SYSTEM WILL DEVELOP AND LINGER OFFSHORE THE SOUTHEAST US COAST LATE FRI THROUGH THE WEEKEND...AND THIS SYSTEM MAY RESULT IN RAIN AND SUB-VFR CONDITIONS AT KFAY/KRWI/KRDU FRI NIGHT-SAT. FORECAST CONFIDENCE REMAINS BELOW AVERAGE REGARDING THE TRACK OF THE LOW AND ASSOCIATED IMPACTS OVER CENTRAL NC...HOWEVER. && .CLIMATE... THE FOLLOWING ARE THE RECORD LOW TEMPERATURES FOR THIS MORNING: THU 04/17 LOW/YEAR FAY: 31/1953 GSO: 29/1953 RDU: 29/1962 && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT THURSDAY FOR NCZ007>011-021>027-038>041-073>077-083>086. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...WSS LONG TERM...BSD AVIATION...MWS CLIMATE...MWS

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