AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 127 AM EDT TUE APR 19 2011 .SYNOPSIS... HIGH PRESSURE WILL REMAIN ANCHORED OVER THE WESTERN ATLANTIC WATERS THROUGH MID-WEEK WHILE A COLD FRONT APPROACHES FROM THE NORTHWEST. THE COLD FRONT WILL SLIDE ACROSS THE EASTERN CAROLINAS AND OFFSHORE EARLY THURSDAY...BRINGING WITH IT THE CHANCE FOR SHOWERS AND POSSIBLY THUNDERSTORMS. COOL HIGH PRESSURE FROM THE NORTH WILL RIDGE ACROSS THE AREA LATE THURSDAY THROUGH FRIDAY. TEMPERATURES WILL GRADUALLY WARM UP DURING THE WEEKEND AS THE HIGH SLIDES OFF THE EAST COAST AND SOUTHERLY FLOW DEVELOPS ACROSS THE AREA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1 AM TUESDAY...A DECENT GRADIENT OF DEWPOINTS EXISTS ACROSS THE COASTAL COUNTIES WITHIN THE ILM CWA WITH UPPER 50S TO LOWER 60S ACROSS THE COASTAL COUNTIES TO LOWER TO MID 50S ELSEWHERE. KNOWING THIS GRADIENT WILL GREATLY AID THE MIN TEMP FORECAST TONIGHT...WITH UPPER 50S TO AROUND 60 DEG AT THE COAST AND LOWER 50S INLAND. TRADITIONAL COLD POCKETS WHERE RADIATIONAL COOLING IS ALLOWED TO MAXIMIZE WILL DIP TO THE LOWER TO MID 40S. DEWPOINTS WILL BE CLOSE TO THRESHOLD FOR THE DEVELOPMENT OF SEA FOG AND STRATUS OVERNIGHT... BUT SHOULD FALL SHORT SO WILL NOT INTRODUCE AT THIS TIME. MODELS HAVE BEEN CONSISTENT WITH PORTRAYING A VERY SHALLOW DEPTH OF MOISTURE NEAR GROUND LEVEL AND SO WITH THAT THERE MAY BE SOME LATE NIGHT STRATUS/FOG...BUT COVERAGE SHOULD BE RATHER LIMITED AS MODELS INDICATE MAINLY SUBSIDENCE ALOFT. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...TEMPERATURES WILL RISE A BIT ABOVE AVERAGE MOST PLACES ON TUESDAY AS HIGH PRESSURE BECOMES ESTABLISHED OVER THE WESTERN ATLANTIC...BRINGING A WARM SOUTHERLY FLOW TO THE REGION. HIGH TEMPERATURES WILL RANGE FROM THE 70S ALONG THE COAST TO THE MID 80S INLAND...WITH LOWS IN THE 60S OVERNIGHT. MODEL SOUNDINGS AND SATELLITE LOOPS SUGGEST WE WILL SEE A GOOD BIT OF CIRRUS ON AND OFF THROUGH THE DAY AND INTO THE NIGHT. BREEZY AND GUSTY DAY WEDNESDAY AS GRADIENT TIGHTENS IN ADVANCE OF A COLD FRONT APPROACHING FROM THE NW. INCREASING SWLY FLOW WILL FURTHER HELP RAISE MAXIMUM TEMPERATURES INTO THE MID TO UPPER 80S MOST LOCATIONS EXCEPT IN THE 70S ALONG THE COAST. SLIGHT CHANCE FOR CONVECTIVE PRECIPITATION AFTER MIDNIGHT AS COLD FRONT MOVES ACROSS THE FORECAST AREA. ALTHOUGH THERE WILL BE SOME DECENT UPPER SUPPORT IN THE FORM OF A VIGOROUS SHORT WAVE...LOW LEVEL MOISTURE SEEMS TO BE LACKING...SO NOT TOO EXCITED AT THE PROSPECTS FOR SIGNIFICANT QPF AT THIS POINT. TEMPERATURES WILL AGAIN BE ABOVE AVERAGE OVERNIGHT...LOW 60S INLAND TO MID 60S ALONG THE COAST. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...PERSISTENT FEATURES WILL BE FLAT RIDGING ALOFT AND SFC HIGH PRESSURE OFF THE COAST. THIS PATTERN WILL BE VERY SIMILAR TO OUR SUMMER BERMUDA HIGH...WITH THE EXCEPTION OF A COLD FRONT DROPPING SOUTH ACROSS THE AREA THURSDAY...AND PROVIDING A SLIGHTLY COOLER ONSHORE FLOW FOR THU NIGHT AND FRI. ONLY LEGITIMATE CHANCE FOR PRECIP IS THURSDAY INTO FRIDAY WITH THIS FRONT...AND WILL BE AMPLY COVERED BY A LOW CHANCE GIVEN FAIRLY DRY WESTERLY FLOW ALOFT. TEMPS NEAR NORMAL THURSDAY NIGHT AND FRIDAY...BUT OTHERWISE 5-10 DEGREES ABOVE CLIMO EACH DAY. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... AS OF 06Z...MODERATE CONFIDENCE IN A VFR FORECAST FOR THE VALID TAF PERIOD...EXCEPT WILL INTRODUCE IFR CONDITIONS AT KCRE AND MVFR AT KMYR...ALTHOUGH CONFIDENCE IS RATHER LOW. NARROWING DEWPOINT DEPRESSIONS THROUGH DAYBREAK. WINDS ABOVE THE BOUNDARY LAYER WILL BE FROM THE SW AT 15 TO 20 KT. WILL INTRODUCE A SCT STRATUS DECK AROUND 300 FT AFTER 08Z THROUGH 12Z. WILL ONLY INCLUDE IFR IN BR AT KCRE AND MVFR AT KMYR WHERE WINDS ABOVE THE BOUNDARY LAYER ARE LIGHTEST DURING THE 08-12Z TIME FRAME. SCT 300 FT DECK COULD BECOME BROKEN DURING THIS TIME FRAME AS WELL...BUT PROBABILITIES TOO LOW TO FORECAST. THEREAFTER...SHOULD GET SOME RATHER FLAT CU OR SC DEVELOPMENT... ESPECIALLY DURING PEAK HEATING. MOISTURE WHILE EVIDENT...IS VERY LIMITED...AND SO WILL ONLY INCLUDE A SCT DECK. ON THE MARINE SIDE OF THE SHARP SEABREEZE BOUNDARY...SKIES WILL BE CLEAR DURING PEAK HEATING. DRY AIR ALOFT AND A TIGHTENING PRESSURE GRADIENT WILL ALLOW FOR A RATHER WELL MIXED ENVIRONMENT AND WE DO EXPECT WIND GUSTS IN THE 20 KT RANGE LATE MORNING AND THROUGH THE EARLY EVE. SEABREEZE WILL ENHANCE WIND SPEEDS AT THE COASTAL TERMINALS. PROSPECTS FOR AN EXPANDING AREA OF STRATUS DURING THE LATE EVE AND OVERNIGHT HOURS TUE NIGHT ARE INCREASING AS LOW LEVEL MOISTURE INCREASES. A 25-30 KT LOW LEVEL JET ABOVE THE BOUNDARY LAYER SHOULD GREATLY LIMIT THE FOG POTENTIAL. WILL INCLUDE A SCT DECK AFTER 02-04Z. LATER FORECASTS MAY INTRODUCE IFR OR LOWER CEILINGS ACROSS AT LEAST SOME OF THE TERMINALS AFTER 05-06Z. EXTENDED OUTLOOK...MODERATE CONFIDENCE IN IFR CEILINGS WEDNESDAY MORNING. LOW CONFIDENCE IN SHOWERS WITH ISOLATED THUNDERSTORMS THURSDAY. SHOWERS MAY PERSIST FRIDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1 AM TUESDAY...THE SFC RIDGE AXIS WILL EXTEND WSW ACROSS THE AREA WATERS FROM THE WESTERN ATLANTIC HIGH OVERNIGHT. A WEAK SSW LOW LEVEL JET WILL BE IN PLACE THROUGH DAYBREAK. SSTS REMAIN COOL ENOUGH TO PREVENT THE FULL EFFECTS OF THE LOW LEVEL JET...AND THUS WILL CONTINUE THE S WIND AROUND 10 KT FORECAST. A PERSISTENT 2-3 FOOT 8-9 SECOND PERIOD EASTERLY SWELL WILL CONTINUE TO AFFECT THE WATERS OVERNIGHT...WITH A RELATIVELY NEGLIGIBLE 1 FOOT LOW PERIOD WIND WAVE. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...HIGH PRESSURE BECOMES ESTABLISHED OVER THE WESTERN ATLANTIC ON TUESDAY...BRINGING A GRADUALLY INCREASING SOUTHERLY FLOW TO THE WATERS...FROM AROUND 10 KTS TUESDAY MORNING TO 15 KTS WEDNESDAY MORNING. SEAS WILL INCREASE FROM 2 TO 3 FT TO 3 TO 4 FT DURING THAT PERIOD. WINDS WILL VEER TO THE SW WEDNESDAY IN ADVANCE OF A COLD FRONT WHICH SHOULD BE LINED UP ALONG THE COAST BY THE END OF THE SHORT TERM. SEAS WILL MAINTAIN IN THE 3 TO 4 FT RANGE. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 3 PM MONDAY...COLD FRONT DROPPING THROUGH THE AREA ON THURSDAY...AND A BIT OF A LOW-CONFIDENCE FORECAST DEPENDENT ON HOW MUCH OF A BACKDOOR PRESENTATION THE FRONT TAKES OUT OVER THE WATERS. WILL INITIALIZE WITH SW AND END UP ENE BY THE END OF THE DAY. FAIRLY CONFIDENT IN VEERING WINDS OVER LAND...BUT THINK THAT THE SEABREEZE PROCESSES WILL MAKE FOR MORE OF A BACKING OVER THE WATER. DECENT ENE SURGE THURSDAY NIGHT COULD PUMP WINDS UP TO 15-20 KT...AND WHEN WE THROW IN A 3 FT ESE SWELL THAT COULD LEAD TO MARGINAL SCA SEAS. SURGE FADES THROUGH THE DAY ON FRIDAY...AND THEN WINDS VEER TO SE FRIDAY NIGHT AND THEN SOUTH ON SATURDAY AS WE RETURN TO A MORE BENIGN PATTERN QUITE SIMILAR TO THE TYPICAL BERMUDA HIGH. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$