Issued by NWS Wilmington, NC
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-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --000 FXUS62 KILM 230333 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 955 PM EST SUN NOV 22 2009 .SYNOPSIS...-- Changed Discussion --LOW PRESSURE WILL RE-DEVELOP OFF THE SOUTHEAST U.S. COAST OVERNIGHT AND MOVE NORTHEAST EARLY THIS MORNING. THE LOW WILL PASS BY THE AREA DURING THE DAY MONDAY WITH A GOOD DOSE OF RAIN ACROSS THE AREA BEFORE ALL SAID AND DONE. THIS WILL BE FOLLOWED BY CLOUDY AND COOL CONDITIONS WITH POSSIBLE DRIZZLE PERSISTING THROUGH ATLEAST TUESDAY. WEDNESDAY AND THURSDAY WILL FEATURE A BRIEF WARM-UP...BUT A COLD FRONT LATE THURSDAY WILL BRING MUCH COLDER CONDITIONS AND THE POSSIBILITY OF FROST OR A FREEZE FOR THE UPCOMING WEEKEND.-- End Changed Discussion --&& .NEAR TERM /THROUGH MONDAY/...-- Changed Discussion --AS OF 930 PM SUNDAY...KLTX 88D HAS INDICATED AREAS OF 3/4 TO 1 1/4 INCH PRECIP AMOUNTS BASICALLY WEST OF I-95. AT THE MOMENT...THE BACK EDGE OF THIS WIDESPREAD PCPN IS LIFTING TO THE NE WITH THE MID LEVEL S/W TROF RESPONSIBLE NOW LIFTING TO THE N OR NE OF THE ILM CWA AT THE MOMENT. THIS BEST SEEN WITH THE LATEST RUC MODEL AND WATER VAPOR IMAGERY. THE NEXT S/W TROF ALOFT OR PIECE OF ENERGY...IS POISED TO MOVE ROUGHLY ACROSS THE AREA BETWEEN 08Z-14Z WITH THE COASTAL AREAS THE PRIMARY AREAS OR THE BETTER PROSPECTS TO RECEIVE PCPN DUE TO THEIR CLOSER PROXIMITY TO THE RELATIVELY STATIONARY FRONTAL BOUNDARY THAT LIES OFFSHORE. THE RUC AND NAM PULL IT SLITLEY CLOSER TO THE COAST...STILL KEEPING IT OFFSHORE...FOR PCPN TO AFFECT MORE-SO THE COASTAL COUNTIES THEN THE INLAND ONES. HAVE REFLECTED THIS THINKING WITH POP AND QPF. THE AREA TO REMAIN IN THE COOL SECTOR AND AT THE MOMENT THE MINS REMAIN ON TARGET.-- End Changed Discussion --&& .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...CHILLY WEDGE CONDITIONS WILL PERSIST THROUGH THIS ENTIRE PORTION OF THE FORECAST. LOW PRESSURE MONDAY MORNING WILL BE CENTERED JUST SOUTHEAST OF CAPE FEAR MOVING NORTHEASTWARD. HIGH PRESSURE BUILDING INTO NEW ENGLAND WILL RIDGE DOWN THE EAST COAST THROUGH TUESDAY...MAINTAINING THE COOL WEDGE CONDITIONS. THE GFS MODEL APPEARS TO BE SUPERIOR TO THE NAM WITH RESPECT TO THE PATH OF THE LOW MONDAY. MODEL CHOICE HAS SIGNIFICANT IMPLICATIONS FOR THE FORECAST MONDAY - THE NAM TRACKS THE LOW JUST ONSHORE AND BRIEFLY BRINGS WILMINGTON INTO THE WARM SECTOR. A MODEL FORECAST SOUNDING FROM THE NAM 18Z MONDAY OVER WILMINGTON SHOWS 1500 J/KG OF CAPE AND A SURFACE TEMPERATURE OF 76! THIS IS NOT THE PREFERRED MODEL SOLUTION AND HAS BEEN IGNORED IN FAVOR OF THE GFS. THE MID-LEVEL DRY SLOT WILL BE SPREADING OVER THE AREA FROM THE SOUTHWEST AROUND DAYBREAK MONDAY...SHUTTING OFF THE SIGNIFICANT RAINFALL. RAIN WILL SHUT OFF FROM SOUTHWEST TO NORTHEAST DURING THE MORNING HOURS WITH ONLY DRIZZLE OR PERHAPS SOME VERY LIGHT RAIN CONTINUING INTO THE AFTERNOON. MONDAY NIGHT WILL BE MURKY WITH LOW CLOUDS AND AREAS OF FOG AND DRIZZLE. CLOUDS AND PATCHY DRIZZLE WILL PERSIST INTO TUESDAY AND PERHAPS TUESDAY NIGHT. WE HAVE GONE VERY CLOSE TO THE GFS MOS HIGHS AND LOWS THROUGH THE PERIOD. THESE GUIDANCE NUMBERS FIT THE CONCEPTUAL PATTERN ASSOCIATED WITH A CLOUDY WEDGE BETTER THAN THE NAM. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 3 PM SUNDAY...WEAK HIGH PRESSURE WEDGE IN PLACE STILL ON WED WITH POTENTIAL FOR ANOTHER CLOUDY AND COOL DAY. BY WED EVENING COASTAL TROUGH BECOMES MORE PRONOUNCED AND LATEST GFS SHOWING ASSOCIATED LOW IN THE GULF MOVING UP THE SOUTHEAST WATERS THROUGH THURS. DRY COLD FRONT PUSHES THROUGH AREA FROM THE WEST ON THURS...COMBINING WITH LOW PRESSURE MOVING UP FROM THE SOUTH TO PRODUCE DEEPENING LOW PRESSURE OFF HATTERAS THROUGH THURS NIGHT AND CONTINUING TO MOVE UP THE COAST AWAY FROM LOCAL AREA THROUGH FRI WHILE PARENT LOW STILL HANGS BACK OVER THE GREAT LAKES. LOOKS LIKE MOST OF PCP WILL REMAIN OFF SHORE WITH POTENTIAL TO MAINLY AFFECT COASTAL AREAS LATE WED INTO THURS WHEN COASTAL TROUGH/LOW REMAINS CLOSEST TO CAROLINA COAST. 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 USHER IN COLDEST AIR FRI THROUGH SAT. CAA WILL CONTINUE INTO SAT ON FRONT END OF STRONG HIGH AMPLITUDE HIGH PRESSURE SYSTEM. BY SUNDAY THIS HIGH PRESSURE SYSTEM WILL CONTINUE TO MOVE EAST WITH CAA SHUTTING OFF AND RIDGE BUILDING ALOFT. OVERALL BEST CAA SHOULD OCCUR THURS NIGHT THROUGH SAT MORNING. LOW LEVEL THICKNESSES BEGIN THE DECLINE FROM NEAR 1360M DOWN TO NEAR 1310M BY FRI MORNING. 850 TEMPS DROP BELOW 0 EARLY FRI. TEMPS WILL HOLD CLOSE TO NORMAL ON WED AND THURS. BY LATE THURS INTO FRI COLD AND DRY HIGH PRESSURE WILL BUILD IN BEHIND STRONG COLD FRONTAL PASSAGE. WITH WINDS HOLDING UP EXPECT TEMPS TO HOLD IN THE MID TO UPPER 30S OVERNIGHT FRI. MUCH BETTER RADIATIONAL COOLING CONDITIONS WILL EXIST OVERNIGHT SAT NIGHT BUT BEST CAA WILL HAVE ENDED BY THEN BUT SHOULD SEE TEMPS IN THE 30S ONCE AGAIN. POTENTIAL FOR FROST OR POSSIBLY FREEZE WILL EXIST BOTH FRI AND SAT NIGHT. DAY TIME HIGHS FRI AND SAT WILL BE BELOW NORMAL. MAY NOT MAKE IT OUT OF THE 50S...ESPECIALLY INLAND. SHOULD SEE GRADUAL WARMING THROUGH THE WEEKEND WITH TEMPS REACHING WITHIN A FEW DEGREES OF 60. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... WIDESPREAD LIGHT TO MODERATE RAIN IS OCCURRING ACROSS THE FLO/LBT TERMINALS THIS EVENING...WITH MORE PATCHY TYPE LIGHT RAIN OCCURRING AT THE COASTAL TERMINALS. CEILINGS ARE GENERALLY VFR. CONTINUITY SUGGESTS THE HEAVIEST OF THE RAIN WILL END BY 02Z-03Z AT FLO/LBT AS DRIER AIR PUNCHES IN ALOFT ACROSS THESE TERMINALS. ALTHOUGH THE DRIER AIR WILL TRY TO MOVE ACROSS THE COASTAL TERMINALS...A LOW PRESSURE AREA MOVING NORTHEAST ALONG THE COAST JUST EAST OF THE COASTAL TERMINALS THIS EVENING AND OVERNIGHT WILL LIKELY CONTINUE TO PRODUCE RAINFALL AT THE COASTAL TERMINALS UNTIL MIDNIGHT OR SHORTLY THEREAFTER. HEAVIEST OF THE SHOWERS SHOULD REMAIN NEAR THE WAVE AND ASSOCIATED TROUGH JUST OFFSHORE. MAINLY TEMPO MVFR CEILINGS AND VISIBILITIES WILL OCCUR THIS EVENING WITH IFR CEILINGS DEVELOPING AFTER 06-08Z. ALTHOUGH IFR CEILINGS ARE NOT EXPECTED THIS EVENING...BRIEF PERIODS OF IFR VISIBILITIES ARE POSSIBLE...ESPECIALLY AT THE COASTAL TERMINALS IF HEAVIER SHOWERS DEVELOP CLOSER TO SHORE. CEILINGS WILL LIKELY DROP TO LIFR AROUND SUNRISE AS THE LOW MOVES FURTHER OFF TO THE NORTHEAST AND HIGH PRESSURE BUILDS IN TRAPPING LOW LEVEL MOISTURE. LIFR CEILINGS SHOULD RISE TO IFR BY AFTERNOON. EXTENDED OUTLOOK...IFR CEILINGS EARLY TUESDAY. IFR VISIBILITIES IN FOG POSSIBLE EACH MORNING. && .MARINE...-- Changed Discussion --NEAR TERM /THROUGH TONIGHT/... AS OF 930 PM SUNDAY...HAVE EXTENDED THE SCA TO 9 AM MONDAY FOR ALL WATERS. THE LOW CONTINUES TO CRANK-UP AND ONLY SLOWLY MOVE NE ALONG THE STATIONARY FRONTAL BOUNDARY THAT CURRENTLY RESIDES PARALLEL TO THE CAROLINA COASTS. MODELS KEEP THE BOUNDARY FROM BEING PULLED INLAND AND CONCUR WITH THIS THINKING DUE TO THE CORRELATION THAT NO TROFFINESS EXISTS ACROSS THE TX-OK AREA THRU MONDAY MORNING. THE LOW AT THE MOMENT SEEMS A BIT STRONGER THEN ANTICIPATED AND IS PRODUCING THE STRONGER ASSOCIATED WINDS ACROSS THE ILM WATERS. LATEST BUOY REPORTS ILLUSTRATE NE SUSTAINED AT 25 KT WITH GUSTS OVER 30 KT. DO NOT EXPECT GALE CONDITIONS BUT WILL HAVE TO REFLECT THE HIER WINDS AND RESULTING HIER SEAS PRODUCTION OVERNITE INTO EARLY MONDAY...A PORTION OF THE SHORT TERM. SHORT TERM/MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...LOW PRESSURE WILL BE LOCATED MONDAY MORNING VERY CLOSE TO THE FRYING PAN SHOALS TOWER. BY MONDAY EVENING THE LOW WILL HAVE MOVED NORTH OF HATTERAS WITH GENERALLY LIGHT NORTHWEST TO NORTH WINDS SPREADING OVER THE WATERS. IN FACT WE WILL MAINTAIN THESE OFFSHORE WIND DIRECTIONS WITH CLOUDY COOL CONDITIONS THROUGH THIS ENTIRE PORTION OF THE FORECAST. ANY RAINFALL MONDAY WILL CLEAR FROM SOUTH TO NORTH DURING THE MORNING HOURS...WITH ONLY SOME PATCHY DRIZZLE EXPECTED MONDAY AFTERNOON THROUGH TUESDAY. VISIBILITY RESTRICTIONS IN DRIZZLE SHOULD NOT BECOME A SIGNIFICANT PROBLEM. SEAS INITIALLY 3-5 FT MONDAY MORNING WILL IMPROVE THROUGH THE DAY AS THE WIND DIRECTIONS BECOME FIRMLY OFFSHORE. WITH WIND SPEEDS REMAINING UNDER 15 KNOTS...NO ADVISORY CONDITIONS ARE EXPECTED. LONG TERM/WEDNESDAY THROUGH THURSDAY/... AS OF 3 PM SUNDAY...WEAK HIGH PRESSURE OVER WATERS THROUGH MID WEEK WITH BENIGN WINDS AND SEAS EXPECTED. OVERALL EXPECT LIGHT OFF SHORE FLOW OR NORTHERLY THROUGH EARLY THURS WITH SEAS LESS THAN 3 FT. LATE WED INTO THURS GRADIENT INCREASES SLIGHTLY AS COLD FRONT PUSHING INTO THE CAROLINAS FROM THE WEST AND COASTAL TROUGH DEVELOPS TO THE SOUTH. EXPECT WINDS AND SEAS TO INCREASE FURTHER THROUGH THURS AFTN INTO FRI AS COLD FRONT APPROACHES AND MOVES THROUGH WITH DECENT 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 FRI.-- End Changed Discussion --&& .ILM WATCHES/WARNINGS/ADVISORIES...-- Changed Discussion --SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST MONDAY FOR AMZ250-252-254- 256.-- End Changed Discussion --&& $$ SYNOPSIS...TRA/DCH NEAR TERM...DCH SHORT TERM...TRA LONG TERM...RGZ AVIATION...MRR
