Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 031214 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 814 AM EDT SUN MAY 3 2015 .SYNOPSIS... LOW PRESSURE SYSTEM WELL OFFSHORE FROM THE NC COAST WILL CONTINUE TO MOVE FURTHER AWAY FROM THE U.S. MAINLAND TODAY. BACK-SWELL FROM THIS SYSTEM WILL AFFECT THE AREA WATERS AND BEACHES THRU TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE NW TODAY...ITS CENTER WILL MOVE OVERHEAD TONIGHT...AND EAST OF THE AREA INTO THE MID-WEEK PERIOD. AT THE SAME TIME...THE HIGH WILL CONTINUE TO RIDGE BACK ACROSS THE FORECAST AREA. A DEVELOPING COASTAL LOW OVER THE BAHAMAS DURING THE MID-WEEK PERIOD...MAY LIFT NORTHEAST AND PARALLEL THE SOUTHEAST U.S. COAST DURING THE UPCOMING MID TO LATE WEEK PERIOD. && .NEAR TERM /THROUGH TONIGHT/... AS OF 615 AM SUNDAY...SYNOPTICALLY...I WILL CALL IT A DIRTY UPPER RIDGE AFFECTING THE FA THIS PERIOD. MEANING...ITS NOT ALL THAT AMPLIFIED AND YOU HAVE WEAK S/W MID-LEVEL TROFS MOVING THROUGH IT. ENOUGH MOISTURE IN THE LOWER LEVELS EXISTS...BELOW 700MB... WHEN EITHER LOOKING AT VARIOUS MODEL SOUNDINGS AND/OR TIME HEIGHT DISPLAYS FOR LOCATIONS ACROSS THE FA. AS A RESULT...SCATTERED TO POSSIBLY BROKEN CU/SC/AC CLOUDS WILL REMAIN POSSIBLE AS THESE UPPER FEATURES PUSH ACROSS THE FA. THE 1ST ONE IS CURRENTLY EXITING THE AREA TO THE SE...AND THE NEXT ONE DROPS DOWN FROM THE NW ACROSS THE FA LATER THIS AFTERNOON AND TONIGHT. NO PCPN EXPECTED DUE TO THE LIMITED VERTICAL EXTENT OF THESE CLOUDS AS SEEN WITH VARIOUS PROGGED SOUNDINGS ACROSS THE FA. AS FOR TEMPS...MOST LOCATIONS SHOULD BREAK 80 WITH THE EXCEPTION OF THE IMMEDIATE COAST. WITH A RELAXED SFC PG AS THE CENTER OF THE SFC HIGH MOVES OVERHEAD TODAY AND LOCAL SSTS IN THE 60S...A DECENT SEA BREEZE SHOULD DEVELOP BY MIDDAY AND PROGRESS INLAND FOR A GOOD WAYS. FOR TONIGHTS LOWS...THE AIR MASS WILL CONTINUE TO MODIFY ESPECIALLY WITH SFC MESOSCALE AND SYNOPTIC SCALE E-SE FLOW BECOMING MORE DOMINANT. LOOK FOR WIDESPREAD 50S FOR LOWS...WITH THE THREAT FOR PATCHY TO AREAS OF FOG AS WINDS LIKELY WILL DECOUPLE AFTER MIDNIGHT TONIGHT. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 AM SUNDAY...BERMUDA HIGH WILL REMAIN THE MAIN SURFACE FEATURE DURING THE PERIOD WHILE ALOFT WEAK 5H RIDGE WILL TRY TO BUILD OVER THE SOUTHEAST. INITIALLY THERE WILL BE RESISTANCE FROM THE REMAINS OF A WEAK 5H SHORTWAVE TROUGH BUT EVENTUALLY THIS WILL BE OVERPOWERED. AS FAR AS LOCAL WEATHER GOES THE REGION WILL REMAIN DRY WITH PLENTY OF SUN AND TEMPERATURES NEAR TO SLIGHTLY ABOVE CLIMO WITH THE EXCEPTION OF HIGHS ALONG THE COAST RUNNING A LITTLE COOLER. THE AFOREMENTIONED SHORTWAVE TROUGH MAY RESULT IN A LITTLE MORE CLOUD COVER ACROSS WESTERN PORTION OF THE FORECAST AREA...ESPECIALLY MON AFTERNOON BUT PRECIP CHANCES WILL REMAIN NEAR ZERO THROUGH TUE NIGHT. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 3 AM SUNDAY...BIG STORY IN THE EXTENDED CONTINUES TO BE THE SYSTEM EXPECTED TO EMERGE FROM THE CARIBBEAN/BAHAMAS MID WEEK. GUIDANCE CONTINUES TO STRUGGLE WITH THE EVOLUTION OF THE SYSTEM AND BOTH THE GFS/ECMWF HAVE BEEN SWINGING BACK AND FORTH BETWEEN A WELL DEFINED HYBRID SYSTEM AND A WEAK BARELY CLOSED OFF LOW ALONG A TROPICAL WAVE. ONE THING THAT SEEMS TO BE FAIRLY CERTAIN IS THE STATE OF THE STEERING FLOW. THE SYSTEM WILL TAKE SHAPE UNDER 5H RIDGING OVER THE SOUTHEAST AND WESTERN ATLANTIC LATER THIS WEEK. THIS WILL WILL LEAD TO THE LOW MEANDERING OFF THE SOUTHEAST COAST FOR MUCH IF NOT ALL OF THE PERIOD. INITIALLY THE LOW IS FAR ENOUGH FROM THE COAST THAT PRECIP IS NOT A CONCERN THUS WILL MAINTAIN THE INHERITED DRY FORECAST WED. POP FORECAST FOR THU THROUGH SAT IS LESS CLEAR. COLD FRONT TRIES TO DROP IN FROM THE NORTH BUT NOT SURE HOW MUCH SUCCESS IT WILL HAVE. HOWEVER THE LOW OFF THE COAST WILL BE WORKING TO SPREAD A SIGNIFICANT AMOUNT OF LOW LEVEL MOISTURE OVER THE SOUTHEAST. THIS SHOULD LEAD TO AN INCREASE IN PRECIP CHANCES LATE IN THE WEEK...ESPECIALLY AS THE MID LEVEL RIDGE SHOULD BE WEAKENING. CONFIDENCE IN THE ULTIMATE TRACK OF THE LOW REMAINS RATHER LOW...ESPECIALLY GIVEN THE VERY WEAK STEERING FLOW SO AT THIS POINT IT IS HARD TO PIN DOWN ANY ONE DAY AS A FAVORED DAY FOR PRECIP. FOR NOW PLAN TO BUMP PRECIP CHANCES LATE IN THE PERIOD A BIT BUT NOT A SIGNIFICANT AMOUNT. HIGH WILL BE NEAR TO SLIGHTLY BELOW CLIMO WITH LOWS RUNNING SLIGHTLY ABOVE. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/...
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AS OF 12Z...MVFR DUE TO AREAS OF FOG THIS MORNING...AND POTENTIAL FOR MVFR/IFR DUE TO FOG OVERNIGHT INTO MONDAY MORNING. OTHERWISE EXPECT VFR. LIGHT WINDS AND NEARLY CLEAR SKIES PREVAIL THIS MORNING WITH AREAS OF FOG CREATING MVFR AT THE COASTAL SITES. ANTICIPATE THIS TO DISSIPATE WITHIN THE NEXT HOUR OR TWO...ALLOWING FOR CONDITIONS TO IMPROVE TO AND PREVAIL AS VFR THROUGH THIS EVENING AS HIGH PRESSURE REMAINS IN PLACE. DO ANTICIPATE FEW/SCT CU TO DEVELOP LATE THIS AFTERNOON AS FCST SOUNDINGS ILLUSTRATE AVAILABLE MOISTURE WITHIN THE ATMOSPHERIC PROFILE. LIGHT WINDS WILL INCREASE TO NORTH-NORTHEAST AROUND 5 KTS THIS MORNING...BECOMING SOUTHEAST IN THE AFTERNOON AOB 10 KTS WITH THE AFTERNOON SEABREEZE. INTO THE OVERNIGHT HOURS AS HIGH PRESSURE GRADUALLY SHIFTS OFFSHORE...LIGHT WINDS AND NEARLY CLEAR SKIES WILL PREVAIL. ANTICIPATE PATCHY FOG DEVELOPMENT LATE OVERNIGHT INTO EARLY MORNING HOURS...POTENTIALLY CREATING MVFR/IFR. EXTENDED OUTLOOK...PRE-DAWN MORNING FOG IS POSSIBLE EACH DAY THAT COULD RESULT IN MVFR/IFR CONDITIONS...OTHERWISE EXPECT VFR.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 620 AM SUNDAY...SFC HIGH PRESSURE TO BASICALLY MOVE OVERHEAD TODAY...AND JUST EAST OF THE AREA WATERS TONIGHT. THEREFORE...THE SFC PG WILL BECOME QUITE RELAXED...YIELDING 10 KT WINDS OR LESS. THE WIND DIRECTION WILL BE TRICKY DEPENDING ON THE ORIENTATION OF THE HIGHS CENTER AS IT MOVES ACROSS THE AREA WATERS. WILL LIKELY HAVE A DECENT SEA BREEZE DEVELOP BY MIDDAY...AND PROGRESS INLAND DURING THE AFTN AND EARLY TO MID EVENING. WINDS NEARSHORE WILL LIKELY BECOME ESE-SSE AT 10 KT...POSSIBLY 10 TO 15 KT AT THE HEIGHT OF THE SEA BREEZE. SIGNIFICANT SEAS WILL RUN AROUND 3 FT. BACK-SWELL FROM THE STACKED LOW WELL OFFSHORE FROM THE CAROLINAS...WILL AFFECT THE LOCAL WATERS THROUGH TONIGHT. THE AREA WATERS WILL HAVE AN ENE 2 TO 3 FOOT 9-11 SECOND PERIOD GROUND SWELL AFFECT THE LOCAL WATERS...AND THIS WILL DOMINATE THE SIGNIFICANT SEAS. SOME OF THIS SWELL ENERGY WILL BE DEGRADED AS IT PUSHES ACROSS FRYING PAN SHOALS PRIOR TO AFFECTING THE AREA WATERS/BEACHES OFF/OF BRUNSWICK COUNTY...AND HENCE THE 1 FOOT LOWER SEAS FORECAST. THE STRENGTH OF THE LOCAL SEA BREEZE MAY PARTIALLY AFFECT THE INTEGRITY OF THIS SWELL. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 AM SUNDAY...BERMUDA HIGH EXTENDING WEST WILL MAINTAIN EAST TO SOUTHEAST FLOW THROUGH THE PERIOD. GRADIENT WILL REMAIN WEAK WITH SPEEDS 10 KT OR LESS. SOME NEAR SHORE ENHANCEMENT WILL BE POSSIBLE EACH AFTERNOON BUT ONSHORE FLOW WILL LIKELY MINIMIZE THE EFFECT OF THE SEA BREEZE. PROLONGED ONSHORE FLOW WILL PUSH 2 FT SEAS ON MON TO 2 TO 3 FT TUE. LONG TERM /WEDNESDAY THROUGH THURSDAY/... AS OF 3 AM SUNDAY...MAIN CONCERN CONTINUES TO BE THE SYSTEM EMERGING FROM THE BAHAMAS AND THE UNCERTAINTY ASSOCIATED WITH IT. BERMUDA HIGH WILL RETREAT ON WED AS THE LOW SLOWLY DRIFTS NORTH. THE LACK OF STEERING FLOW MEANS THE LOW WILL DRIFT SLOWLY ALTHOUGH THE DIRECTION REMAINS A QUESTION. FOR NOW WILL SHOW WINDS BACKING TO NORTHEAST WED AND REMAINING NORTHEAST THU. GRADIENT SHOULD START TO INCREASE LATER IN THE PERIOD ALTHOUGH THE INCREASE IS NOT LIKELY TO BE A LOT. WILL SHOW NORTHEAST FLOW INCREASING LATE BUT STILL HAVE SPEEDS BELOW HEADLINE CRITERIA. EXTENDED PERIOD OF NORTHEAST FETCH WILL SLOWLY BUILD SEAS FROM 2 TO 4 FT WED MORNING TO 3 TO 6 FT BY THE END OF THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...III NEAR TERM...DCH SHORT TERM...III LONG TERM...III AVIATION...SGL

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