Area Forecast Discussion Issued by NWS Wilmington, NC -------------------------------------------------------------------------------- 000 FXUS62 KILM 291042 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 642 AM EDT TUE OCT 29 2013 .SYNOPSIS... A WARMING TREND WILL CONTINUE IN THE DAYS AHEAD WITH TEMPERATURES RUNNING ABOVE NORMAL TODAY THROUGH FRIDAY. A COLD FRONT WILL BRING UNSETTLED WEATHER LATE FRIDAY INTO SATURDAY...FOLLOWED BY MUCH COLDER AND DRIER HIGH PRESSURE LATE SATURDAY THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM TUESDAY...TODAY`S 500 MB PATTERN WILL FEATURE SLOWLY RISING HEIGHTS AS YESTERDAY`S DISTURBANCE PUSHES OFFSHORE AND A LOW-AMPLITUDE RIDGE POKES NORTH FROM THE GULF OF MEXICO. THE RIDGE AT 850 MB IS PARKED OVER GEORGIA...AND AT THE SURFACE THE HIGHEST PRESSURES ARE NOTED OVER THE EASTERN GREAT LAKES. PREVAILING SURFACE WINDS FROM THE NORTH WILL TURN MORE EASTERLY WITH TIME THIS AFTERNOON...WITH SPEEDS REMAINING LIGHT. DEEP HIGH PRESSURE SHOULD PROVIDE A RATHER PLEASANT DAY ONCE MORNING FOG BURNS OFF. ALTHOUGH VISIBILITIES HAVE DROPPED AS LOW AS 1/4 MILE AT TIMES EARLY THIS MORNING...THESE LOW VISIBILITIES HAVE BEEN TOO SPATIALLY AND TEMPORALLY INCONSISTENT TO CONSIDER A DENSE FOG ADVISORY. TRENDS WILL BE CLOSELY MONITORED THROUGH DAYBREAK. 00Z MODELS INITIALIZED VERY WELL WITH THE THERMAL PROFILE OF THE ATMOSPHERE VERSUS 00Z MHX AND GSO BALLOON SOUNDINGS...AND THERE IS VERY LITTLE SPREAD IN MODEL FORECAST HIGHS FOR THIS AFTERNOON. HIGHS SHOULD REACH THE MID 70S WITH PERHAPS SOME UPPER 70S IN THE DARLINGTON/FLORENCE/KINGSTREE AREA. A WEAK SEABREEZE THIS AFTERNOON SHOULD HOLD THE BEACHES A FEW DEGREES COOLER. FOR TONIGHT SOME CIRRUS WILL BEGIN TO SPILL OVER THE RIDGE FROM THE WEST...BUT SKIES SHOULD AVERAGE MOSTLY CLEAR. LOWS SHOULD REACH 50-55...WARMEST ALONG THE BEACHES. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 330 AM TUESDAY...HIGH PRESSURE EXTENDING DOWN ALONG THE EAST COAST ON WED WILL MOVE OUT TO SEA BY THURS AS A COLD FRONT APPROACHES FROM THE WEST. WARM WEATHER WILL CONTINUE AS RIDGE BUILDS UP FROM THE GULF WITH INCREASING H5 HEIGHTS UP THROUGH THURS NIGHT. LOW LEVEL THICKNESSES AND 850 TEMPS SHOW A STEADY RISE THROUGH THE PERIOD WITH 850 READINGS INCREASING FROM 8C WED MORNING UP TO 12C BY THURS EVENING. THIS WILL PRODUCE UNSEASONABLY WARM WEATHER WITH TEMPS REACHING CLOSER TO 80 UNDER AUTUMN SUNSHINE. OVERNIGHT LOWS WILL ALSO REMAIN WELL ABOVE NORMAL AS ON SHORE FLOW WILL KEEP A STEADY RISE IN DEWPOINT TEMPS KEEPING TEMP READINGS FROM DROPPING MUCH BELOW THE MID 50S ON WED NIGHT. BY THURS NIGHT INCREASING CLOUDS AND MOISTURE AHEAD OF THE APPROACHING COLD FRONT WILL YIELD TEMPS ABOVE 60 MOST PLACES. THE CAROLINAS WILL REMAIN ON TOP OF THE MID TO UPPER RIDGE WITH A GOOD DEAL OF DRY AIR AND SUBSIDENCE IN THE MID LEVELS OF THE ATMOSPHERE...KEEPING PCP AT BAY THROUGH THE PERIOD. THERE WILL BE A GENERAL RISE IN MOISTURE THROUGH THE COLUMN DUE TO INCREASING ON SHORE FLOW THROUGH THE LOW LEVELS AND SOME CIRRUS STEAMING OVER THE TOP OF THE RIDGE. WOULD ALSO EXPECT SOME FOG AROUND THE AREA. WINDS WILL BE LIGHT AND VARIABLE ON WED AS THE HIGH PRESSURE NEARLY OVERHEAD MOVES OUT TO SEA AND WINDS SHIFT AROUND BECOMING MORE ON SHORE AND THEN SOUTHEAST BY THE END OF THE DAY ON WED. BY THURS A WARMER AND MOISTER RETURN FLOW WILL SET UP EVENTUALLY INCREASING AS GRADIENT TIGHTENS BETWEEN COLD FRONT AND HIGH PRESSURE OFF SHORE. THE MODELS HAVE GENERALLY SLOWED DOWN THE PROGRESSION OF THE FRONT WITH PCP HOLDING OFF ACROSS MUCH OF AREA UNTIL LATER ON FRI. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 330 AM TUESDAY...THE MODELS HAVE GENERALLY SLOWED AND WEAKENED WITH THE PROGRESSION OF THE FRONT WITH BRUNT OF PCP MOVING THROUGH AREA FRI AFTN THROUGH FRI NIGHT. AHEAD OF THE FRONT THERE WILL BE A GENERAL INCREASE IN LOW LEVEL WINDS AND MOISTURE AS SOUTHERLY SURFACE WINDS COMBINE WITH AN INCREASING LLJ UP TO 45 KTS. A WESTERLY FLOW ALOFT WILL ALSO CONTINUE TO FEED IN INCREASING MID TO HIGH CLOUDS THROUGH THURS NIGHT INTO FRIDAY. MAY SQUEEZE OUT A FAIRLY DECENT DRY MORNING ON FRI BUT WITH A FAIR AMOUNT OF CLOUDS AND MAY ALSO HAVE TO CONTEND WITH SOME MORNING FOG...ESPECIALLY ALONG THE CAPE FEAR COAST. TEMPS SHOULD SHOOT UP INTO THE 70S AFTER A WARM START TO THE MORNING. EXPECT SHOWERS TO INCREASE ACROSS WESTERN AREAS IN THE I-95 CORRIDOR THROUGH EARLY AFTERNOON. THE COLD FRONT WILL BE SLOW TO MOVE THROUGH THE CAROLINAS AS MID TO UPPER LEVEL FLOW WILL BE ALIGNED WITH BOUNDARY NOT ALLOWING IT TO GIVE MUCH OF A PUSH EASTWARD. THEREFORE BEST PCP CHANCES WILL COME WITH ACTUAL FROPA FRIDAY NIGHT...INTO SATURDAY MORNING ALONG THE COAST. LOW LEVELS DRY OUT SATURDAY BY THE DEEPER LAYER DRY AIR ADVECTION WILL HAVE TO WAIT FOR THE MID TO UPPER TROUGH AXIS TO SWEEP THROUGH LATE SATURDAY. PCP WATER VALUES REACHING UP CLOSE TO 2 INCHES ALONG AND JUST AHEAD OF COLD FRONT WILL DROP OUT TO LESS THAN A HALF INCH BY SAT NIGHT INTO SUNDAY. THEREFORE EXPECT DRYING AND CLEARING THROUGH SATURDAY WITH PLENTY OF CAA TO COME LATER IN THE DAY. GFS SHOWS 850 TEMPS PLUMMETING FROM 14C SAT AFTN DOWN TO 2C BY SUN MORNING. THEREFORE EXPECT TEMPS TO WARM INTO THE 70S ONCE AGAIN EARLY ON SATURDAY IN A WESTERLY DOWNSLOPE FLOW BEFORE DEEP NW FLOW DEVELOPS ALLOWING PLENTY OF COLD AND DRY CANADIAN AIR TO ADVECT INTO THE COASTAL CAROLINAS INTO EARLY NEXT WEEK AS STRONG AND LARGE AREA OF HIGH PRESSURE SHIFTS EAST INTO THE EASTERN CONUS. TEMPS WILL BE ALMOST 20 DEGREES COOLER BY EARLY SUNDAY MORNING THAN PREVIOUS NIGHTS AND WILL ONLY REACH THE 60S ON SUNDAY. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... AS OF 12Z...QUITE A BIT OF UNCERTAINTY WITH RESPECT TO FOG/STRATUS OVER THE NEXT COUPLE OF HOURS. MORPHING MID CLOUD IS DIFFICULT TO PREDICT...AND AREAS THAT HAVE A MID CLOUD CEILING WILL SCOUR OUT FOG...AT LEAST TEMPORARILY. LOOK FOR ALL TERMINALS TO IMPROVE TO VFR BY 14Z. BROAD AREA OF HIGH PRESSURE TO THE NORTH WILL KEEP US IN MAINLY NORTHEAST FLOW THROUGH THE DAY...STRONGEST NEAR THE COAST DUE TO WEAKER FRICTIONAL FORCES. LIGHT WINDS TONIGHT WITH SOME FOG POSSIBLE TOWARD THE END OF THE FORECAST PERIOD. EXTENDED OUTLOOK...EARLY MORNING FOG POSSIBLE WEDNESDAY. CHANCE OF SHOWERS FRIDAY INTO SATURDAY WITH AN APPROACHING COLD FRONT. OTHERWISE VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM TUESDAY...HIGH PRESSURE CENTERED OVER THE EASTERN GREAT LAKES WILL MIGRATE OFF THE EAST COAST TONIGHT...WITH A RIDGE AXIS EXTENDING SOUTHWARD THROUGH THE INTERIOR CAROLINAS. THIS SHOULD ENSURE A PREVAILING NORTH TO NORTHEAST WIND THROUGH TONIGHT...WITH THE EXCEPTION NEARSHORE THIS AFTERNOON WHERE A WEAK SEABREEZE SHOULD TURN WIND DIRECTIONS MORE ONSHORE. REGARDLESS...WIND SPEEDS SHOULD REMAIN LESS THAN 12 KNOTS. THERE IS VERY LITTLE VARIANCE BETWEEN MODELS LEADING TO A HIGH- CONFIDENCE FORECAST. SEAS CURRENTLY AVERAGE 2 FEET WITH THE BULK OF THE WAVE ENERGY IN A 7-8 SECOND SOUTHEAST SWELL. STRONGER NORTH WINDS OFFSHORE MAY ADD UP TO A FOOT TO SEA HEIGHTS AWAY FROM SHORE THIS AFTERNOON...BUT LITTLE CHANGE IS EXPECTED NEARSHORE. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 330 AM TUESDAY...HIGH PRESSURE EXTENDING DOWN ALONG THE EAST COAST ON WED WILL SHIFT OFF SHORE BY THURS AS A COLD FRONT APPROACHES FROM THE WEST. WINDS VEER AROUND BECOMING MORE ON SHORE AND THEN SE BY LATE WED AS THE HIGH PRESSURE NEARLY OVERHEAD MOVES OUT TO SEA. BY THURS AN INCREASING RETURN FLOW WILL SET UP AS GRADIENT TIGHTENS BETWEEN APPROACHING COLD FRONT AND HIGH PRESSURE OFF SHORE. EXPECT WINDS E-SE ON WED AROUND 10 KTS OR LESS TO INCREASE UP TO 15 TO 20 KTS BY LATE THURS INTO FRI. SEAS 3 FT OR LESS THROUGH EARLY THURS WILL TAKE AN UPSWING THROUGH THE DAY ON THURS WITH A STRONG SOUTHERLY PUSH BUILDING SEAS UP TO 4 TO 5 FT IN OUTER WATERS BY EARLY FRI MORNING. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 330 AM TUESDAY...STIFF SOUTHERLY WINDS UP AROUND 15 TO 20 KTS WILL PERSIST IN TIGHTENED GRADIENT FLOW BETWEEN APPROACHING COLD FRONT AND HIGH PRESSURE OFF SHORE. WINDS MAY REACH OVER 20 KTS AS THEY VEER SLIGHTLY TO THE SW BY FRI NIGHT. EXPECT SEAS TO REACH NEAR OR ABOVE SCA THRESHOLDS THROUGH FRI AND SHOULD REACH ABOVE 6 FT BY SAT MORNING IN STRONG S-SW PUSH. BY SAT AFTN WIND WILL BEGIN TO VEER AROUND AS COLD FRONT MAKES ITS WAY EAST SLOWLY. ONCE MID TO UPPER TROUGH DRIVES IT THROUGH THE WATERS BY SAT NIGHT...STRONG NW FLOW AND PLENTY OF CAA WILL BRING SURGE IN WINDS UP TO 20 TO 25 KTS. THE OFF SHORE COMPONENT TO THE FLOW BY SAT AFTN WILL KEEP HIGHEST SEAS OFF SHORE WITH SEAS RANGING FROM 3 TO 6 FT THROUGH SAT NIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...TRA SHORT TERM...RGZ LONG TERM...RGZ AVIATION...43 --------------------------------------------------------------------------------
Posted on: Tue, 29 Oct 2013 12:09:51 +0000
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