Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 040716 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 316 AM EDT MON MAY 4 2015 .SYNOPSIS... THE CENTER OF A HIGH PRESSURE SYSTEM WILL DRIFT SLOWLY OFFSHORE THROUGH EARLY THIS WEEK...PROVIDING SUNSHINE AND SEASONABLE MAY TEMPERATURES. A COASTAL LOW IS EXPECTED TO FORM IN THE BAHAMAS MID-WEEK...AND MEANDER ALONG THE SOUTHEAST COAST THROUGH THE END OF THE WEEK AND INTO NEXT WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 130 AM MONDAY...DRY AND SEASONABLE WEATHER WILL CONTINUE OVERNIGHT AS HIGH PRESSURE SLIPS FURTHER OFF SHORE WITH A LIGHT RETURN FLOW PROVIDING A SLIGHT INCREASE IN MOISTURE. THERE WILL BE PLENTY OF SUBSIDENCE AND DRY AIR THROUGH THE MID TO UPPER LEVELS WITH ONLY LIMITED LOW LEVEL MOISTURE THROUGH THE COLUMN AS MID TO UPPER RIDGE TRIES TO BUILD OVERHEAD. IT WILL BE DISRUPTED BY A SHORTWAVE RIDING DOWN IN THE NORTHWEST FLOW ALOFT WHICH WILL REACH THE CENTRAL CAROLINAS BY DAY BREAK. THIS SHOULD NOT PRODUCE ANYTHING MORE THAN SOME MID TO HIGH CLOUDS. THE AIR MASS WILL CONTINUE TO MODIFY IN E-SE RETURN FLOW AS SFC HIGH SHIFTS FARTHER EAST THROUGH THE EARLY MORNING HOURS. THIS WILL ALLOW FOR MODEST MOISTURE RETURN WITH DEWPOINT TEMPS REACHING BACK FROM LOWER 40S THIS AFTERNOON UP TO THE MID 50S OVERNIGHT. EXPECT TEMPS TO SLOW DOWN AND REMAIN IN THE MID 50S MOST PLACES. ALSO EXPECT PATCHY TO AREAS OF FOG AS TEMPS AND DEWPOINT TEMPS CONVERGE UNDER LIGHT TO CALM WINDS AND LIMITED CLOUD COVER. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...BERMUDA HIGH ON TUESDAY WILL RETREAT WEDNESDAY AHEAD OF DISTURBANCE EMERGING FROM THE CARIBBEAN AND THE BAHAMAS. MID LEVEL RIDGING IN PLACE ABOVE THE BERMUDA HIGH TUE WILL MAINTAIN WARM AND DRY CONDITIONS ACROSS THE AREA WITH ONLY PATCHES OF SHALLOW AFTERNOON CU. ONSHORE FLOW WILL CONTINUE KEEPING TEMPS NEAR THE COAST AROUND CLIMO WHILE INLAND AREAS WARM UP A BIT. SECOND HALF OF THE PERIOD STARTS TO GET INTERESTING AS THE SYSTEM EMERGING FROM THE BAHAMAS WILL TRY AND COALESCE INTO A WELL DEFINED LOW. THE GOING WILL INITIALLY BE SLOW AND THE LACK OF STEERING FLOW ALOFT IS LIKELY TO KEEP THE SYSTEM SOUTH OF THE AREA THROUGH THE END OF THE PERIOD. STILL A LOT OF UNCERTAINTY REGARDING THIS SYSTEM AND WHILE IT MAY LEAD TO AN INCREASE IN CLOUD COVER...ESPECIALLY ALONG THE COAST WED NIGHT...DO NOT THINK IT WOULD DIRECTLY AFFECT THE REGION BEFORE THE END OF THE PERIOD. THUS WILL MAINTAIN THE DRY FORECAST WITH HIGHS AROUND CLIMO AND LOWS A BIT ABOVE CLIMO. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 3 AM MONDAY...LONG TERM PERIOD WILL BE DOMINATED BY THE LOW EVOLVING OFF THE SOUTHEAST COAST MID TO LATE WEEK. GUIDANCE CONTINUES TO STRUGGLE WITH THIS SYSTEM...MAINLY DUE TO THE LACK OF ANY REAL STEERING FLOW ALOFT. HOWEVER SOME SOLUTIONS SEEM HARD TO BUY. FOR INSTANCE THE LOW DEEPENING AND MOVING UP THE COAST SEEMS THE LEAST LIKELY OUTCOME GIVEN THE 5H RIDGING TO THE NORTH. DO THINK THE LOW COULD GRADUALLY STRENGTHEN THROUGH THE PERIOD. ALTHOUGH THE WATER TEMPS WITHIN THE GULF STREAM ARE AROUND 80 AND SHEAR SHOULD BE WEAK TO NONEXISTENT THERE ARE SEVERAL FACTORS THAT WOULD LIMIT STRENGTHENING. A LACK OF DIFFLUENCE ALOFT EARLY IN THE PERIOD AND THE LARGE SWATH OF SEA SURFACE TEMPS OUTSIDE THE GULF STREAM IN THE 60S BEING THE BIGGEST. SO WHILE SOME DEVELOPMENT OF THIS SYSTEM IS EXPECTED A FULL BLOWN TROPICAL SYSTEM SEEMS TO BE A LONG SHOT. INSTEAD THE SYSTEM WILL PROBABLY ACQUIRE SOME TROPICAL CHARACTERISTICS BUT REMAIN QUITE WEAK AS IT WANDERS OVER THE WATERS OFF THE SOUTHEAST COAST. WORTH NOTING A LOT OF THE GFS ENSEMBLES TAKE THE WEAK LOW INTO FL OR SOUTHERN GA...SOMETHING WHICH A FAIR NUMBER OF THE MEMBERS HAVE BEEN CONSISTENTLY SHOWING OVER THE LAST FEW DAYS. LOCALLY IMPACTS THROUGH THE PERIOD WILL BE NORTHEAST FLOW...WITH SOME ENHANCEMENT LATER IN THE WEEK AND AN INCREASE IN LOW LEVEL MOISTURE. THIS SHOULD BRING ABOUT AN INCREASE IN PRECIP CHANCES...ESPECIALLY ALONG THE COAST...AS THE WEEK WEARS ON. GIVEN THE LOW CONFIDENCE PLAN TO MAKE ONLY SMALL CHANGES TO THE INHERITED FORECAST WHICH WILL NOW CARRY CHC POP THROUGH THE PERIOD WITH TEMPS NEAR TO SLIGHTLY ABOVE CLIMO. && .AVIATION /07Z MONDAY THROUGH FRIDAY/... AS OF 06Z...NOT MUCH SYNOPTICALLY DIFFERENT FROM YESTERDAY...WITH HIGH PRESSURE OFFSHORE GIVING US SOUTHEAST FLOW. THERE IS FOG POTENTIAL AGAIN OVERNIGHT...MAINLY AFTER 08Z. CRE STANDS THE BEST CHANCE AGAIN...BUT COULD NOT RULE OUT INLAND FOG EITHER. DO NOT THINK WE WILL SEE THE LIFR CONDITIONS THAT WE EXPERIENCED LAST NIGHT. MONDAY...BECOMING VFR AT ALL LOCATIONS WITH CONTINUED SOUTHEAST FLOW...STRONGEST ALONG THE COAST. EXTENDED OUTLOOK...PRE-DAWN MORNING FOG IS POSSIBLE EACH DAY THAT COULD RESULT IN MVFR/IFR CONDITIONS. UNSETTLED WEATHER THURSDAY NIGHT THROUGH SATURDAY WITH A SUBTROPICAL LOW. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 130 AM MONDAY...HIGH PRESSURE WILL SHIFT FARTHER OFF SHORE OVERNIGHT. THEREFORE EXPECT A VERY LIGHT RETURN FLOW TO CONTINUE BASICALLY LESS THAN 10 KTS. SEAS WILL RUN UNDER 3 FT MOST WATERS WITH A A VERY SLOW DECLINE THROUGH TONIGHT WITH SUCH LIGHT WINDS AND DIMINISHING LONGER PERIOD BACKSWELL FROM LOW MOVING OFF INTO THE DISTANT ATLANTIC WATERS. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...BERMUDA HIGH WILL MAINTAIN LIGHT EASTERLY FLOW TUE INTO WED. DURING THE SECOND HALF OF THE PERIOD THE HIGH WILL RETREAT NORTHEAST AS WEAK LOW PRESSURE EMERGES FROM THE BAHAMAS. WINDS WILL BACK TO NORTHEAST FOR WED AND WED NIGHT WITH A SLIGHT BUMP IS SPEED. CONFIDENCE WITH RESPECT TO THE AMOUNT OF STRENGTHENING THE LOW WILL UNDERGO AND ITS LOCATION IS RATHER LOW AND THUS FORECAST CONFIDENCE IS ALSO LOW. FOR NOW KEEPING WIND SPEEDS WED AND WED NIGHT CONFINED TO THE 15 TO 20 KT RANGE BUT HIGHER VALUES ARE POSSIBLE. SEAS 2 TO 3 FT TUE INTO WED SHOULD BUILD LATER WED AS NORTHEAST FLOW INCREASES AND COASTAL LOW STARTS TO BECOME A LITTLE MORE DEFINED. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 3 AM MONDAY...MUCH OF THE FORECAST DEPENDS ON THE DETAILS OF THE HYBRID TROPICAL SYSTEM MEANDERING OFF THE SOUTHEAST COAST LATE THIS WEEK. WEAK STEERING FLOW ALOFT HAS SO FAR BEFUDDLED GUIDANCE AND NOT CONFIDENT CLARITY WILL DESCEND UPON THE FORECAST IN THE NEAR TERM. THAT SAID FEEL A FORECAST OF NORTHEAST FLOW IN THE 15 TO 20 KT RANGE IS A GOOD COMPROMISE AND IS IN LINE WITH PREVIOUS FORECASTS. SEAS WILL BUILD ON THE BACK OF EXTENDED NORTHEAST FLOW WITH SOME ZONES LIKELY TO EXCEED 6 FT IN PLACES ON THU AND REMAIN ABOVE 6 FT FRI. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...REK/RGZ SHORT TERM...III LONG TERM...III AVIATION...DL

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