AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 301 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 /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3:00 AM TUESDAY...CONTINUED TO FAVOR THE GFS THROUGH THE PERIOD ESPECIALLY LATE WHEN THE NAM IS FASTER AND DRIER WITH THE COLD FRONT MOVING ACROSS FROM THE WEST. HIGHEST POPS VIA THE MAV OCCUR INLAND LATE WEDNESDAY AND DURING THE DAY ALONG THE COAST. TIMING MITIGATES SEVERE THREAT ALTHOUGH THERE IS SOME MIXED LAYER CAPE AVAILABLE WITH MINIMAL SHEAR. THE LATEST DAY TWO OUTLOOK FROM SPC CLIPS WESTERN COUNTIES. MAINTAINED THUNDER AS THE WEATHER TYPE. AFTER A WARM DAY WEDNESDAY THURSDAY WILL RESIDE AT THE OTHER END OF THE SPECTRUM WITH TEMPERATURES TWO TO THREE CATEGORIES BELOW WEDNESDAY`S VALUES. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3:00 AM TUESDAY...EXTENDED FORECAST CONTINUES TO FEATURE MINIMAL POPS AND FORCING WITH TEMPERATURES SOMEWHAT ABOVE NORMAL. CHANCE POPS REMAIN IN FOR FRIDAY WITH THE FRONT IN THE VICINITY. THE LATEST GFS HAS TRENDED DRIER ALTHOUGH FOR THE FORECAST FROM HPC APPLIES A BLEND OF THE LAST NIGHTS ECMWF AND GFS. FRONT DISSIPATES AS BERMUDA HIGH PRESSURE BECOMES THE DOMINANT FEATURE SATURDAY. A COUPLE OF SYSTEMS WILL MAKE A RUN TO THE AREA FROM THE WEST NORTHWEST AND SLIGHT CHANCE POPS ARE CONFINED TO THE INLAND AREAS TO ADDRESS THIS SCENARIO THROUGH THE REMAINDER OF THE PERIOD. && .AVIATION /07Z 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 /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3:00 AM TUESDAY...SOUTHWEST FLOW WILL INCREASE THROUGHOUT THE DAY WEDNESDAY AS A FRONT MOVING IN FROM THE WEST AND RETREATING HIGH PRESSURE TEAM UP. WINDS LATER IN THE DAY WILL INCREASE TO A RANGE OF 15-20 KNOTS. FRONT WILL MOVE ACROSS THE WATERS THURSDAY WITH A STRONGER NORTHEASTERLY FLOW DEVELOPING IN ITS WAKE. TRIMMED BACK THE GFS WINDS A BIT ALTHOUGH SPEEDS HOVERING NEAR 20 KNOTS REMAIN. WITH THE STRONGER WINDS SWAN HAS INCREASED SEAS TO JUST OVER THE SIX FOOT THRESHOLD FOR A SMALL CRAFT ADVISORY BEGINNING NORTHEAST ZONES AND PUSHING SOUTH BY FRIDAY MORNING. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3:00 AM TUESDAY...EASTERLY FLOW INITIALLY WILL VEER TO SOUTHEAST LATE FRIDAY/EARLY SATURDAY AS BERMUDA HIGH PRESSURE BECOMES THE DOMINANT FEATURE FOR THE REGION. EXPECT WIND SPEEDS TO BE REPRESENTATIVE OF THIS FEATURE WITH 10-15 KNOTS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...RJD