Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 161755 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 155 PM EDT WED APR 16 2014 .SYNOPSIS... UNSEASONABLY STRONG...POLAR HIGH PRESSURE WILL BUILD EAST ACROSS THE MIDDLE ATLANTIC AND NORTHEAST STATES THROUGH THURSDAY. && .NEAR TERM /THROUGH THURSDAY NIGHT/... AS OF 1035 AM WEDNESDAY... UPPER LEVEL HEIGHTS WILL GRADUAL INCREASE ACROSS THE CAROLINAS THIS AFTERNOON AND TONIGHT AS L/W TROUGH JUST OFFSHORE CONTINUES TO LIFT NEWD INTO THE CANADIAN MARITIME PROVINCES. CANADIAN HIGH PRESSURE OVER THE OH VALLEY THIS MORNING WILL TRANSLATE E-NE THIS AFTERNOON IN THE WAKE OF THE TROUGH THEN STRENGTHEN AND BECOME ANCHORED OVER NORTHERN NEW ENGLAND BY THURSDAY MORNING DUE TO CONFLUENT MID-UPPER LEVEL FLOW. LOW LEVEL N-NE FLOW THROUGH TONIGHT WILL RESULT IN CAA RESULTING IN LOW LEVEL THICKNESSES THIS AFTERNOON AS MUCH AS 50-55M BELOW NORMAL...SUPPORTIVE OF MAX TEMPS 15-20 DEGREES BELOW NORMAL. FORECAST MAX TEMPS IN THE LOW-MID 50S APPEAR ON TARGET AT THIS TIME. -WSS TONIGHT: (NEAR) RECORD COLD. PROJECTED LOW LEVEL THICKNESS VALUES AROUND 1305 METERS AT GSO AT 12Z THU...WITH OPTIMAL RADIATIONAL COOLING...WOULD SUPPORT MIDDLE 20S. HOWEVER...A PROJECTED 4-6 MB RISE TONIGHT IN MSL PRESSURE WITH THE AFOREMENTIONED STRENGTHENING HIGH TO OUR NORTH WILL LIKELY MAINTAIN A NORTHEASTERLY STIRRING FOR MOST AREAS...THOUGH WEAKEST AND WITH LIKELY PERIODS OF CALM IN CLOSEST PROXIMITY TO THE RIDGE AXIS...OVER THE WESTERN/SOUTHERN PIEDMONT. MEANWHILE THE NE STIRRING WILL BE MORE PRONOUNCED IN A STRONGER MSL PRESSURE GRADIENT/AWAY FROM THE RIDGE AXIS...OVER THE COASTAL PLAIN. IN ADDITION...ATLANTIC MOISTURE ADVECTION IN NORTHEASTERLY FLOW BENEATH THE CAPPING INVERSION MAY RESULT IN SCT TO BKN LOW CLOUDS MAINLY IN THE COASTAL PLAIN LATE. AS SUCH...TEMPERATURES ARE APT TO DISPLAY A RELATIVELY LARGE RANGE...FROM 27-30 DEGREES IN RURAL WESTERN PIEDMONT LOCATIONS (IN CLOSEST PROXIMITY TO THE RIDGE AXIS) TO AROUND FREEZING IN URBAN AREAS FROM RDU WESTWARD TO THE TRIAD...TO 33-37 DEGREES IN THE COASTAL PLAIN AND EASTERN SANDHILLS. THU AND THU NIGHT: GRADUAL MODIFICATION OF THE UNSEASONABLY STRONG/1045 MB POLAR HIGH CENTERED OVER MAINE EARLY THU WILL ENSUE FOR THE LATTER HALF OF THE WEEK. THE AFOREMENTIONED MOISTURE IN NE FLOW WILL RESULT IN THE DEVELOPMENT/WESTWARD EXPANSION OF A MOSTLY SCATTERED STRATOCUMULUS FIELD WITH DIURNAL HEATING THU...PERHAPS BRIEFLY BROKEN IN EASTERN AREAS...WITH DRY ADIABATIC MIXING AGAIN THROUGH 900 MB SUPPORTIVE OF HIGHS MAINLY BETWEEN 60 AND 65 DEGREES - IN LINE WITH PROJECTED 24 HOUR LOW LEVEL THICKNESS RISES OF ABOUT 30 METERS OF THOSE OF WED. CHILLY WITH GOOD RADIATIONAL COOLING... DESPITE A FEW LINGERING STRATOCUMULUS AND THE ARRIVAL OF A THIN VEIL OF CIRRUS ATTENDING A SOUTHERN STREAM WAVE - LOWS OF 36 TO 42 DEGREES. PATCHY FROST WILL BE POSSIBLE IN RURAL WESTERN PIEDMONT LOCATIONS. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 240 AM WEDNESDAY... HIGH PRESSURE RIDGING INTO THE REGION FROM THE NE AND THE SUBSEQUENT NORTHEASTERLY WINDS WILL RESULT IN CONTINUED CAA INTO CENTRAL NC ON FRIDAY. FAIRLY CONFIDENT THERE WILL AT LEAST BE DESCENT COVERAGE OF HIGH CLOUDS OVER THE AREA SO...FOR NOW...EXPECT HIGHS ON FRIDAY MAINLY IN THE LOW TO MID 60S. THERE IS SOME UNCERTAINTY FOR THE FORECAST FRIDAY NIGHT INTO SATURDAY. BOTH MODELS HAVE AN UPPER LEVEL TROUGH MOVING THROUGH THE AREA...HOWEVER THE ECMWF CUTS OFF A LOW OFF THE COAST OF FL SATURDAY MORNING WHERE IT STALLS OUT...WHILE THE GFS TROUGH PROGRESSES OFF THE ATLANTIC COAST BY SATURDAY NIGHT. AS A RESULT...THE ECMWF FORECASTS RAIN MOVING INTO THE SOUTHEAST FRIDAY NIGHT/SATURDAY WHILE THE GFS REMAINS DRY. GIVEN THE UNCERTAINTY WILL KEEP FORECAST DRY...ALTHOUGH CONFIDENCE IS NOT PARTICULARLY HIGH. OVERNIGHT LOWS BOTH FRIDAY AND SATURDAY NIGHTS GENERALLY IN THE MID 40S NW TO AROUND 50 DEGREES SE. HIGHS WITH THE SURFACE RIDGE WEAKENING ON SATURDAY EXPECT HIGHS MAINLY IN THE LOW TO MID 70S. && .LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 240 AM WEDNESDAY... AS THE LOW OFF THE ATLANTIC COAST MOVES FURTHER AWAY FROM NC... EXPECT HIGH PRESSURE TO BUILD BACK INTO THE AREA FOR SUNDAY AND MONDAY...RESULTING IN MAINLY CLEAR/SUNNY SKIES AND DRY WEATHER. HIGHS MAINLY IN THE LOW TO MID 70S...LOWS SUNDAY NIGHT IN THE UPPER 40S TO AROUND 50 DEGREES. MODELS INDICATE AN UPPER LEVEL SHORTWAVE WILL APPROACH CENTRAL NC MONDAY NIGHT AND PROGRESS THROUGH THE AREA THROUGH TUESDAY NIGHT. THOUGH THE MODELS ARE NOT IN COMPLETE AGREEMENT WITH THE SPECIFICS ABOUT THIS FEATURE...THERE WILL AT LEAST BE A SLIGHT CHANCE FOR SOME RAIN DURING THIS TIME...THUS WILL KEEP SLIGHT CHANCES FOR RAIN IN THE FORECAST. HIGHS GENERALLY AROUND 70 DEGREES TUESDAY AND WEDNESDAY...WITH OVERNIGHT LOWS AROUND 50 DEGREES. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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AS OF 155 PM WEDNESDAY... HIGH PRESSURE BUILDING INTO CENTRAL NC FROM THE NORTH WILL MAINTAIN VFR CONDITIONS THROUGH THURSDAY MORNING. BREEZY NE WINDS EARLY THIS AFTERNOON WITH GUSTS 20-25KTS WILL SUBSIDE AFTER 21Z. BY SUNSET... EXPECT SFC WINDS FROM THE NE BETWEEN 4-8KTS. THE CIRCULATION AROUND THE SFC HIGH WILL RESULT IN A LONG NE FETCH OFF THE ATLANTIC INTO EASTERN NC. THIS WILL TRANSPORT A THIN SHALLOW LAYER OF MOISTURE INTO OUR EASTERN TERMINALS...CAUSING A LAYER OF STRATOCU TO DEVELOP SHORTLY AFTER SUNRISE WITH CLOUD BASES BETWEEN 2500-4000FT. MAY SEE A 3-5 HOUR WINDOW OF BROKEN CEILINGS IN THE VICINITY OF KRWI AND POSSIBLY KFAY LATE THURSDAY MORNING THROUGH EARLY AFTERNOON. OUTLOOK...A DEVELOPING LOW PRESSURE SYSTEM IN VICINITY OF THE NE GULF AND THE FL PENINSULA MAY SPREAD ENOUGH MOISTURE INTO EASTERN NC BY LATE FRIDAY THROUGH SATURDAY TO CAUSE A PERIOD OF MVFR/IFR CEILINGS. AT THIS TIME...APPEARS THE BEST CHANCE FOR RAIN WILL BE CONFINED TO THE COASTAL AREAS. IMPROVING WEATHER CONDITIONS AND ASSOCIATED VFR PARAMETERS ANTICIPATED SUNDAY AND MONDAY.
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&& .CLIMATE... THE FOLLOWING ARE THE RECORD LOW TEMPERATURES FOR THU MORNING...AND THE RECORD LOW MAXIMUM TEMPERATURES FOR TODAY: WED 04/16 THU 04/17 LOW MAX/YEAR LOW/YEAR FAY: 56/1950 31/1953 GSO: 48/1929 29/1953 RDU: 46/1890 29/1962 && .RAH WATCHES/WARNINGS/ADVISORIES... FREEZE WARNING FROM MIDNIGHT TONIGHT TO 10 AM EDT THURSDAY FOR NCZ007>010-021>026-038>041-073>077-083>086. FREEZE WATCH FROM LATE TONIGHT THROUGH THURSDAY MORNING FOR NCZ011-027. && $$ SYNOPSIS...MWS NEAR TERM...WSS/MWS SHORT TERM...KC LONG TERM...KC AVIATION...WSS CLIMATE...MWS

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