Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 312336 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 736 PM EDT MON AUG 31 2015 .SYNOPSIS...
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LOW PRESSURE ALONG THE NORTH CAROLINA COAST SHOULD MOVE NORTHEAST AND AWAY FROM THE AREA TONIGHT. A LINGERING TROUGH WILL REMAIN ACROSS THE EASTERN CAROLINAS TUESDAY. HIGH PRESSURE WILL BUILD INTO THE AREA FROM THE NORTH FRIDAY NIGHT AND THROUGH THE WEEKEND.
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&& .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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AS OF 730 PM MONDAY...THE DEEP TROPICAL MOISTURE CHANNEL IS FINALLY BEGINNING TO SHIFT OFFSHORE. WATER VAPOR IMAGERY SHOWS THE LEADING/EASTERN EDGE OF THE DRY AIR NOW ON THE NORTH CAROLINA COAST. LOCALLY HEAVY RAIN CONTINUES TO FALL HOWEVER AS SURFACE LOW PRESSURE AND ITS ASSOCIATED MAXIMUM IN LOW-LEVEL CONVERGENCE IS CENTERED JUST EAST OF CAPE FEAR. THE 12/18Z MODELS WERE QUITE POOR WITH THE ACCURACY OF THE POSITION OF THIS LOW. OF ALL THE MODELS AVAILABLE TO US ONLY THE 12Z WRF-NMM AND 12Z WRF-ARW SHOWED THE LOW IN THE PROPER POSITION AT 21Z. THESE TWO MODELS ARE THE BASIS FOR THE UPDATED FORECAST THIS EVENING. THE LOW SHOULD MOVE NORTHEASTWARD THIS EVENING AND AWAY FROM SOUTHEASTERN NORTH CAROLINA. RAINFALL SHOULD SLOWLY TAPER OFF OVER THE NEXT 2-3 HOURS...LINGERING FOR COASTAL PENDER COUNTY AND THE ADJACENT OCEAN WATERS THE LONGEST. AN ADDITIONAL ONE-HALF INCH TO ONE INCH OF RAIN COULD POTENTIALLY FALL FROM WRIGHTSVILLE BEACH TO TOPSAIL ISLAND OVER THE NEXT FEW HOURS. ONCE THE PRECIP CLEARS THE COAST...CLEAR SKIES ADVANCING IN FROM THE WEST SHOULD OVERSPREAD MOST OF THE AREA. HOWEVER...MODELS ARE INDICATING WRAP-AROUND MOISTURE WILL RE-ENTER THE PICTURE FROM THE NORTH...SPREADING A DECK OF LOW STRATUS INTO AT LEAST SOUTHEASTERN NORTH CAROLINA AFTER MIDNIGHT. WHERE THESE LOW CLOUDS DO NOT REACH...BETTER RADIATIONAL COOLING CONDITIONS WILL INTERSECT WITH LINGERING SURFACE MOISTURE AND WE CAN EXPECT AREAS OF FOG TO DEVELOP. MOS GUIDANCE IS INDICATING THIS FOG COULD BECOME LOCALLY DENSE...PARTICULARLY ACROSS SOUTH CAROLINA`S PEE DEE REGION.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... AS OF 300 PM MONDAY...PROGRESSIVE PATTERN THROUGH THE PERIOD. A TROUGH OF LOW PRESSURE WILL BE ALIGNED RIGHT ALONG THE COAST TUE. A MID-LEVEL VORTICITY MAXIMA ASSOCIATED WITH FORMER TROPICAL STORM ERIKA WILL BE MOVING UP THE SOUTHEAST COAST. THIS FEATURE WILL BE APPROACHING THE FORECAST AREA TUE NIGHT AND IS EXPECTED TO MOVE OFF THE CAROLINA COAST DURING THE DAY WED. A RIDGE BUILDING ACROSS THE MIDDLE OF THE COUNTRY NEAR THE END OF THE PERIOD WILL ALLOW A NW FLOW TO DEVELOP ACROSS THE CAROLINAS. A WEAK SHORTWAVE EMBEDDED IN THE FLOW IS FORECAST TO APPROACH LATE WED NIGHT. THERE WILL BE A GOOD AMOUNT OF DRY AIR MOVING ACROSS THE AREA AND THIS IN AND OF ITSELF WILL BE GOOD REASON TO KEEP THE POPS IN SLIGHT CHANCE/CHANCE CATEGORY. WILL SHOW HIGHEST POPS ALONG THE COAST AHEAD OF AFOREMENTIONED MID-LEVEL VORTICITY...LATE TUE NIGHT AND WED MORNING. HOWEVER...IT MAY END UP THAT MOST OF THE PRECIPITATION AND CERTAINLY THE HEAVIEST OF THE SHOWER AND THUNDERSTORM ACTIVITY...WILL BE OFFSHORE. WILL ALSO TRY TO CAPTURE THE SLIGHT UPTICK IN THE POTENTIAL FOR CONVECTION WED NIGHT WITH THE MID-LEVEL SHORTWAVE. TEMPERATURES WILL RETURN TO SLIGHTLY ABOVE SEASONABLE LEVELS FOR EARLY SEPTEMBER. && .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 300 PM MONDAY...THURSDAY SHOULD BE THE FIRST FULL DAY WHERE THE AREA IS NO LONGER DEALING WITH ANY REMNANTS OF ERIKA. PW DROPS TO ABOUT 1.6 INCHES ACROSS MUCH OF THE AREA BUT THERE WILL BE A MID LEVEL DISTURBANCE MOVING THROUGH IN NORTHWEST FLOW. GFS NOW SHOWS A VERY WEAK ATTENDANT SURFACE FEATURE AND SO FEEL THAT THE LOW END SCATTERED (30 POPS) THAT WE HAVE IN THE FORECAST IS JUST FINE. QPF PROSPECTS WILL BE LOW DUE TO THE LOWER AVAILABLE MOISTURE AND WEAK FORCING. ANOTHER MID LEVEL FEATURE CROSSES ON FRIDAY BUT IN MORE OF WESTERLY RATHER THAN NORTHWESTERLY SOURCE WHICH MAY FAVOR BETTER RAIN CHANCES DUE TO DEEPER MOISTURE AT LEAST ACCORDING TO ECMWF. GFS HAS MORE OF A REPEAT OF THURSDAY. LARGE UPPER RIDGE BUILDS OVER THE EASTERN U.S. AND MID-ATLANTIC OVER THE WEEKEND WITH ITS CENTER WELL TO OUR NORTH. THE SAME WILL HOLD TRUE AT THE SURFACE. THIS WILL BRING A DEEP EASTERLY FLOW TO THE AREA THAT OFTEN LEADS TO TROPICAL BLUE SKIES LADEN WITH TOWERING CU AND ALSO A FEW STRAY SHOWERS MAINLY ALONG THE COAST. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/...
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AS OF 00Z...A MIXTURE OF VFR/MVFR/IFR ON TAP TONIGHT THROUGH THE EARLY MORNING HOURS ON TUESDAY AS AREAS OF FOG AND LOW CIGS DEVELOP. CONDITIONS IMPROVE TO VFR LATE TUESDAY MORNING AND CONTINUE THROUGH THE END OF THE VALID TAF PERIOD. SHOWERS CONTINUE TO MOVE THROUGH PORTIONS OF THE FORECAST AREA THIS EVENING...CURRENTLY AFFECTING KILM...AS SEEN BY LATEST RADAR IMAGERY. EXPECT THIS ACTIVITY TO TAPER OFF OVER THE NEXT COUPLE OF HOURS AND FOR SKIES TO GRADUALLY CLEAR...AS ALREADY SEEN INLAND ON SATELLITE IMAGERY. OTHER THAN INTERMITTENTLY LINGERING FEW/SCT MID CLOUDS INTO THE OVERNIGHT HOURS...MAINLY CLEAR SKIES AND LIGHT WINDS WILL NOT LAST LONG AS SOME GUIDANCE SUGGESTS MOISTURE RETURN OVERNIGHT. AS A RESULT...ANTICIPATE STRATUS AND FOG DEVELOPMENT OVERNIGHT TO CREATE MVFR/IFR CONDITIONS. CONFIDENCE REMAINS LOW REGARDING WHICH FEATURE WILL PREVAIL...THUS HAVE KEPT A MIXTURE IN GOING FORECAST ATTM. ON TUESDAY...CONDITIONS WILL IMPROVE TO VFR WITH LIGHT WINDS BECOMING SOUTHEAST AOB 10 KTS IN THE AFTERNOON. CANNOT ENTIRELY RULE OUT AN ISOLATED SHRA/TSRA IN THE AFTERNOON HOURS. EXTENDED OUTLOOK...PREDOMINATELY VFR WITH BRIEF MORNING FOG AND ISOLATED/SCATTERED AFTERNOON CONVECTION.
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&& .MARINE...
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NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM MONDAY...USING RADAR IMAGERY AND SURFACE OBSERVATIONS LOW PRESSURE IS CENTERED JUST EAST OF CAPE FEAR AT 7 PM. OF ALL THE MODELS AVAILABLE TO US THE TWO THAT SEEM TO HAVE THE BEST HANDLE ON THE CURRENT POSITION AND MOVEMENT OF THIS FEATURE ARE THE 12Z WRF-NMM AND 12Z WRF-ARW. THESE MODELS ARE THE BASIS FOR THIS EVENING UPDATE. OFFSHORE WINDS SHOULD GRADUALLY DIMINISH THROUGH THE NIGHT SOUTH OF CAPE FEAR...BUT NORTH OF CAPE FEAR WE`VE GOT A FEW MORE HOURS OF INTERESTING WEATHER AS SWIRLING WINDS UP TO 20 KNOTS AND WIDESPREAD SHOWERS WITH HEAVY RAINFALL WILL CONTINUE. SEAS HAVE BUILT TO A SOLID 4 FEET NEAR AND NORTH OF CAPE FEAR AND THERE SHOULD BE SOME 5-FOOTERS DEVELOPING SHORTLY ACCORDING TO OUR LOCAL WAVE MODEL USING UPDATED WIND FORECASTS. AN EXERCISE CAUTION HEADLINE HAS BEEN HOISTED NORTH OF CAPE FEAR. AFTER MIDNIGHT SEAS SHOULD SUBSIDE THROUGHOUT THE REGION TO 2-3 FEET. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 300 PM MONDAY...A SLACK PRESSURE GRADIENT IS EXPECTED TO BE IN PLACE THROUGH THE PERIOD AND THIS SHOULD KEEP WIND SPEEDS TO 10 KT OR LESS. SW TO S WINDS DURING THE AFTERNOON AND EVE BOTH DAYS SHOULD BECOME MORE OFFSHORE OVERNIGHT AND DURING THE MORNING DUE TO A LAND BREEZE MOVING OFFSHORE. SEAS WILL BE MAINLY 2 FT...BUT UP TO 3 FT TUE. A WEAK 8 TO 10 SECOND SE SWELL WILL PERSIST. LONG TERM /THURSDAY THROUGH SATURDAY/... AS OF 300 PM MONDAY...WIND SPEEDS WILL BE CAPPED AT JUST 10 KNOTS THROUGH MOST OF IF NOT THE ENTIRE PERIOD. IT MAY STRUGGLE THURSDAY AND FRIDAY TO FIND AN ESTABLISHED DIRECTION HOWEVER THOUGH NORTH AND EAST COMPONENTS WILL TEND TO BE FAVORED. THIS WILL BE FORTIFIED FRIDAY NIGHT INTO SATURDAY AS A STRONGER HIGH GETS ESTABLISHED ACROSS NORTHEASTERN U.S. BETWEEN THE LENGTHENING SPATIAL AND TEMPORAL FETCH ON SATURDAY THE WAVE FORECAST MAY RISE FROM 2 TO 2-3 FT.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM...TRA SHORT TERM...RJD LONG TERM...MBB AVIATION...SRP

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