Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 170712 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 311 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/... 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. && .SHORT TERM /FRIDAY /... 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. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/...
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AS OF 309 AM THURSDAY... THE UPPER LEVEL LOW EXITS THE SOUTHEAST COAST ON SUNDAY... AND NORTHEASTERLY FLOW WILL CONTINUE BEHIND THE DEPARTING SYSTEM... WITH A GRADUAL DECREASE IN CLOUD COVER FROM WEST TO EAST THROUGH THE DAY. HIGHS IN THE MID TO UPPER 60S. SHORTWAVE RIDGING BUILDS IN BRIEFLY ON MONDAY... BEFORE ANOTHER SOUTHERN STREAM WAVE CROSSES THE AREA LATER TUESDAY INTO EARLY WEDNESDAY... BRINGING A TROUGH/WEAK COLD FRONT THROUGH. AT THIS POINT WILL CAP AT A SLIGHT CHANCE POP FOR TUESDAY AFTERNOON AHEAD OF THE FRONT... AS THE NW FLOW SHOULD NOT SUPPORT MUCH IN THE WAY OF MOISTURE TRANSPORT. UPPER LEVEL RIDGING BUILDS IN TO THE AREA FOR THE LATTER PART OF THE PERIOD... AHEAD OF AN AMPLIFIED WESTERN CONUS TROUGH. TEMPERATURES WILL MODERATE INTO THE LOW 70S ON MONDAY TO MID 70S ON WEDNESDAY... WITH LOWS IN THE LOW 50S.
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&& .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...SEC AVIATION...MWS CLIMATE...MWS

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