Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000 FXUS62 KRAH 161903 AFDRAH AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 301 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 /... 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 /FRIDAY NIGHT THROUGH WEDNESDAY/...
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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.
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&& .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... 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. && .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...BSD AVIATION...WSS CLIMATE...MWS

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