000 FXUS62 KILM 232313 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 612 PM EST MON NOV 23 2009 .SYNOPSIS... CLOUDY CONDITIONS ARE EXPECTED TONIGHT THROUGH TUESDAY AS RESIDUAL MOISTURE IS LIFTED OVER COOL AIR NOSING SOUTH FROM NEW ENGLAND. LOW PRESSURE DEVELOPING EARLY WEDNESDAY OVER FLORIDA WILL MOVE NORTHEAST ALONG THE CAROLINA COAST THURSDAY. THIS LOW WILL BE CLOSELY FOLLOWED BY A COLD FRONT THAT WILL USHER IN COLDER AIR FOR THE WEEKEND...ALONG WITH THE POTENTIAL FOR FROST OR FREEZING CONDITIONS. && .NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM MONDAY...SURFACE LOW CURRENTLY EAST OF CAPE FEAR WILL CONTINUE TO MOVE SLOWLY NORTH-NORTHEAST THIS EVENING AND OVERNIGHT. MEASURABLE PRECIP HAS ENDED WITH ONLY PATCHES OF LIGHT DRIZZLE EXPECTED TO CONTINUE THROUGH THE EVENING HOURS. AS THE LOW EXITS OVERNIGHT HIGH PRESSURE BUILDING IN FROM THE NORTH WILL REGAIN CONTROL WITH LOW CLOUDS AND NORTHERLY FLOW THROUGH THE REMAINDER OF THE PERIOD. LOW CLOUD COVER AND SURFACE WINDS AROUND 5 MPH WILL KEEP TEMPERATURES AS MUCH AS 10 DEGREES ABOVE CLIMO OVERNIGHT. WARMEST WILL BE ALONG THE COAST...BUT DO NOT EXPECT MUCH DIFFERENCE BETWEEN THE COAST AND THE COOLEST INLAND SITES. DID NOT CONTINUE DRIZZLE BEYOND MIDNIGHT WITH CROSS SECTIONS AND FORECAST SOUNDINGS MOIST LAYER DROPPING BELOW 2K FT AND WINDS JUST ABOVE THE SURFACE BECOMING MORE WESTERLY. SOME PATCHY FOG MAY DEVELOP INLAND...NOT EXPECTING WIDESPREAD VISIBILITY RESTRICTIONS. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...MODELS ARE NOT IN AGREEMENT WITH HOW TO HANDLE THIS PORTION OF THE FORECAST. ALL GUIDANCE INCLUDING THE CANADIAN AND ECMWF WAS PERUSED AND TWO CAMPS OF MODEL SOLUTIONS ARE EVIDENT. MOST OF THE GUIDANCE SHOWS LOW PRESSURE DEVELOPING OVER FLORIDA EARLY WEDNESDAY...TRACKING UP THE SOUTHEAST COAST AND SPREADING A BAND OF GENERALLY LIGHT RAIN INTO THE COASTAL COUNTIES WEDNESDAY INTO WEDNESDAY NIGHT. THE NAM SHOWS A MUCH WEAKER AND FARTHER EAST LOW WHICH DOES NOT SPREAD MOISTURE FAR ENOUGH WEST TO HAVE ANY IMPACT ON OUR WEATHER. THIS EXPLAINS THE NAM MOS GUIDANCE SHOWING MUCH DRIER AND COOLER WEATHER...ESPECIALLY ON WEDNESDAY. HPC SUGGESTS...AND WE AGREE...THAT THE NAM IS LIKELY AN OUTLIER AND THAT THE LOW WILL INDEED TRACK CLOSE ENOUGH TO THE COAST TO SPREAD SOME RAIN INLAND. OUR FORECAST IS THEREFORE LITTLE CHANGED FROM THE PREVIOUS SHIFT. PRECIPITATION CHANCES WEDNESDAY INTO WEDNESDAY NIGHT WILL RANGE FROM 40% ALONG THE COAST TO 20% ON THE I-95 CORRIDOR. OFFSHORE RAIN CHANCES ARE BETTER THAN 50/50. DAY/NIGHT TEMPERATURE RANGES WILL BE COMPRESSED DUE TO PLENTY OF CLOUD COVER EXPECTED. EVEN TUESDAY SHOULD REMAIN CLOUDY DUE TO RESIDUAL EFFECTS FROM THE COLD AIR WEDGE. OUR TEMPERATURE FORECASTS ARE VERY CLOSE TO THE GFS MOS GIVEN ITS CLOUDIER OUTLOOK COMPARED TO THE NAM. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...HIGH AMPLITUDE MID TO UPPER TROUGH WILL DIG DOWN FROM THE GREAT LAKES DOWN TO THE GULF COAST THURS INTO FRI WHILE IT PUSHES EASTWARD THROUGH TIME ACROSS THE EASTERN CONUS. THIS SYSTEM WILL PUSH A STRONG COLD FRONT THROUGH ON THURS. A COASTAL TROUGH/LOW OFF THE NORTH CAROLINA COAST THURS MORNING COULD INITIALLY PROVIDE SOME EARLY PCP ON THURS BUT WILL MOVE OFF TO THE NORTHEAST AS FRONT MOVES OFF SHORE. THEREFORE ALL WEATHER WILL CLEAR OUT THROUGH THURS LEAVING PLENTY OF COOL AND DRY AIR IN PLACE. A VERY SHARP GRADIENT WILL EXIST INITIALLY WITH PCP WATER VALUES UP OVER AN INCH ALONG THE COAST AND LESS THAN A HALF INCH INLAND...BUT BY THURS EVENING A STRONG WESTERLY FLOW ALOFT WILL CARRY PLENTY OF DRY AIR INTO THE CAROLINAS. WILL SEE PCP WATER VALUES DOWN TO LESS THAN A QUARTER OF AN INCH BY FRI MORNING. ONCE COLD FRONT MOVES THROUGH ON THURS PLENTY OF DRY AND COLD AIR WILL MOVE IN BEHIND IT WHILE H5 LOW STILL REMAINS BACK OVER THE GREAT LAKES KEEPING W-SW FLOW ALOFT. ONCE THE MID TO UPPER TROUGH SWINGS THROUGH ON FRI...DEEP LAYER NW FLOW WILL REINFORCE CAA FRI THROUGH SAT. NORTHWEST FLOW WILL CONTINUE INTO SAT ON FRONT END OF HIGH PRESSURE SYSTEM. LOW LEVEL THICKNESSES TAKE A DEEP PLUNGE LATE THURS INTO FRI MORNING FROM NEAR 1370 THURS AFTN DOWN TO LESS THAN 1320 BY FRI MORNING AND THEN CONTINUE A GRADUAL DECLINE EVEN FURTHER TO AROUND 1310 BY SAT MORNING. 850 TEMPS DROP BELOW 0C FRI MORNING AND REMAIN BELOW THROUGH EARLY SAT. THEREFORE TEMPS WILL START OUT AT OR ABOVE CLIMO...IN THE MID 60S ON THURS BEFORE A COOLING TREND BEGINS BEHIND COLD FRONT. TEMPS THURS NIGHT MAY STAY A LITTLE WARMER IN THE 40S MOST PLACES...BUT BY FRI PLENTY OF COLD AND DRY AIR WILL BRING DEW POINT TEMPS DOWN TO THE LOWER 30S BY FRI NIGHT. HIGHS ON FRI WILL MOST LIKELY NOT MAKE IT OUT OF 50S WITH CAA IN FULL SWING. BY FRI NIGHT TEMPS WILL DROP INTO THE 30S. HIGH PRESSURE WILL MIGRATE EASTWARD THROUGH SAT AS STRONG RIDGE BUILDS ALOFT. THIS SHOULD HELP MODERATE TEMPS HEADING INTO THE SECOND HALF OF THE WEEKEND AND EARLY NEXT WEEK. ALTHOUGH BEST CAA WILL END BY SAT MORNING CLEAR SKIES AND CALM WINDS WILL PRODUCE IDEAL RADIATIONAL COOLING CONDITIONS SAT NIGHT KEEPING TEMPS DOWN IN THE 30S ONCE AGAIN. HIGH TEMPS SAT SHOULD BEGIN TO MODIFY BUT WITH SUCH A COOL START EXPECT HIGHS IN 50S IN MOST PLACES ONCE AGAIN. WILL CONTINUE ON A WARMING TREND THROUGH SUN WITH PLENTY OF SUNSHINE EXPECT TEMPS BACK TOWARD NORMAL...IN THE MID 60S. ANOTHER COOL NIGHT SUN NIGHT DOWN IN THE 40S AND THEN AS HIGH SLIPS OFF SHORE A WARMER RETURN FLOW SETS UP THROUGH MONDAY. AFTER A VERY DRY PERIOD FROM FRI THROUGH SUN...CHANCES OF PCP WILL START TO ENTER BACK IN THE PICTURE MON INTO TUES AS MOISTURE INCREASES IN RETURN FLOW BETWEEN NEXT STORM SYSTEM APPROACHING FROM THE WEST AND HIGH PRESSURE TO THE EAST. && .AVIATION /00Z MONDAY THROUGH SATURDAY/...WEAK WEDGE IN PLACE...AND LIKELY WILL REMAIN THROUGH THE END OF THE FORECAST PERIOD. CEILINGS WILL LOWER DIURNALLY...WITH LIFR FOG POSSIBLE BY MIDNIGHT. CEILINGS WILL BE SLOW TO IMPROVE...LIKELY REMAINING IFR THROUGH THE AFTERNOON...WITH SOME IMPROVEMENT IN VISIBILITIES BY MID TO LATE MORNING. NORTH NORTHWEST FLOW WILL BECOME MORE NORTHEASTERLY BY MIDDAY TUESDAY. EXTENDED OUTLOOK...IFR CEILINGS CONTINUE THROUGH TUESDAY. IFR VISIBILITIES IN FOG TUESDAY AND WEDNESDAY MORNINGS. IMPROVING CONDITIONS THURSDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM MONDAY...SMALL CRAFT ADVISORY FOR NC WATERS HAS BEEN ALLOWED TO EXPIRE BUT RAISED A SCEC THROUGH 6 WITH SEAS CONTINUING TO SUBSIDE THROUGH THE EVENING. WAVES REMAIN ON THE STEEP SIDE WITH PERIODS IN THE 4 TO 6 SEC RANGE. SURFACE LOW JUST EAST OF CAPE FEAR WILL CONTINUE ITS SLOW NORTH-NORTHEAST MOVEMENT THIS EVENING AND OVERNIGHT. HIGH PRESSURE BUILDING IN WILL KEEP NORTHEAST FLOW OVER THE WATERS...BUT RELAXED GRADIENT WILL RESULT IN SPEEDS 10 TO 15 KT WITH SEAS CONTINUING TO FALL...ENDING UP BETWEEN 3 AND 4 FT BY THE END OF THE PERIOD. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...HIGH PRESSURE OVER NEW ENGLAND WILL EXTEND DOWN THE U.S. EAST COAST TUESDAY MORNING...BUT WILL LOSE ITS INFLUENCE LATER IN THE DAY AS LOW PRESSURE BEGINS TO ORGANIZE OVER CENTRAL FLORIDA. THIS LOW IS EXPECTED TO TRACK NORTHEASTWARD AND JUST OFF THE NC/SC COAST WEDNESDAY AND WEDNESDAY NIGHT. ALTHOUGH THERE IS SIGNIFICANT SPREAD IN MODEL SOLUTIONS...IT APPEARS WINDS WILL NOT INCREASE BEYOND 15 KNOTS AT ANY POINT TUESDAY THROUGH WEDNESDAY NIGHT...WITH DIRECTIONS VARYING FROM NORTHEAST THROUGH NORTHWEST. MUCH FARTHER OFFSHORE...CONDITIONS WILL BE MUCH STORMIER AND WE ARE EXPECTING CONSIDERABLE BACKSWELL TO THE MOVING INTO THE CAROLINA COASTAL WATERS WITH SEAS BUILDING TO 3-5 FT. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 3 PM MONDAY...COASTAL TROUGH/LOW OFF NORTH CAROLINA COAST MAY PRODUCE TRICKY FORECAST FOR WINDS THURS MORNING...BUT MOST WATERS SHOULD START OUT WITH NORTHERLY WINDS. OVERALL EXPECT LIGHT OFF SHORE FLOW OR NORTHERLY THROUGH EARLY THURS WITH SEAS LESS THAN 3 FT. BY THURS AFTERNOON A STRONG COLD FRONT WILL MOVE THROUGH THE WATERS WITH DECENT COLD SURGE BEHIND IT. THEREFORE EXPECT WINDS AND SEAS TO INCREASE FURTHER THROUGH THURS AFTN INTO FRI IN COLD SURGE AND ENHANCED GRADIENT FLOW. MAY SEE SEAS UP NEAR 4 TO 5 FT IN OUTER WATERS IN STRONGER W-NW FLOW THURS NIGHT THROUGH EARLY SAT...WITH WINDS GREATER IN COLDER AIR IN WELL MIXED ATMOSPHERE OVERNIGHT. AS HIGH PRESSURE MIGRATES EASTWARD THROUGH SAT WINDS WILL LIGHTEN UP AND BECOME MORE VARIABLE THROUGH SAT NIGHT WITH SEAS DECREASING TO LESS THAN 2 FT BY END OF PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...III SHORT TERM...TRA LONG TERM...RGZ AVIATION...43