Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 310007 AFDILM AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 807 PM EDT THU JUL 30 2015 .SYNOPSIS... LOW PRESSURE OFF THE SOUTHEAST COAST WILL SLOWLY SHIFT TO THE NORTHEAST AWAY FROM THE AREA AS A COLD FRONT MOVES INTO THE AREA FRIDAY. THIS FRONT WILL STALL OVER THE WEEKEND BEFORE DISSIPATING EARLY NEXT WEEK. BERMUDA HIGH PRESSURE WILL EXPAND WESTWARD TUESDAY THROUGH THURSDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 730 PM THURSDAY...THE LATEST SFC PRESSURE PATTERN OVERLAYED BY RADAR 0.5 DEGREE 88D REFLECTIVITY AND VIS SAT IMAGERY...ILLUSTRATES THE LATEST POSITIONING OF THE SFC COLD FRONT AS IT SLOWLY SNAKES TO THE EAST. SOME INTERACTION OF THE SEA BREEZE AND CURRENT CONVECTION ILLUSTRATE THE RATHER "HO-HUM" NATURE OF THE CONVECTION. PART OF THIS DUE TO SUBSIDENCE AND DRIER AIR ALOFT OFTEN PREVENTING ANY FURTHER DEVELOPMENT. WITH THE SOURCE OF SFC LIFT IE. DYNAMICS FROM THE COLD FRONT AND THE DECAYING SEA BREEZE...HAVE OPTED TO CONTINUE A LOW CHANCE POP THRU THE REMAINDER OF THE EVENING AND INTO THE PRE-DAWN FRI HOURS. DIFFICULT TO FIND ANY MID OR UPPER LEVEL DYNAMICS THAT COULD POSSIBLY INTENSIFY OR FURTHER SUSTAIN THE CONVECTION THRUOUT THE EVENING AND OVERNIGHT HOURS. THE CAA TO LAG BEHIND THE COLD FRONT BUT THE DRIER AIR SHOULD ATLEAST WORK INTO THE FAR NW PORTIONS OF THE FA BY DAYBREAK FRI. PREVIOUS........................................................ AS OF 330 PM THURSDAY...LOW PRESSURE IS LOCATED A LITTLE OVER 200 MILES EAST OF BEAUFORT SOUTH CAROLINA. THIS LOW HAS BEEN BATTLING DRY AIR IMPINGING ON THE CIRCULATION FROM THE NORTH. THIS...PLUS NORTHEASTERLY SHEAR HAS PREVENTED SIGNIFICANT DEEPENING VIA WARM CORE/TROPICAL PROCESSES. THE 12Z GFS AND NAM APPEAR FAR TOO EAGER TO ABSORB THE LOW AND MID LEVEL CIRCULATION WITHIN THE BROADER WIND FIELD AROUND THE COLD FRONT APPROACHING FROM THE WEST TONIGHT. THE 17Z RUN OF THE RUC APPEARS MUCH MORE REASONABLE AS ITS INITIALIZED POSITION OF THE LOW IS MUCH CLOSER TO WHERE IT APPEARS ON VISIBLE SATELLITE. COMPARED TO THE NAM AND GFS THIS MEANS A SLOWER VEERING OF SURFACE WIND DIRECTIONS...LIGHTER OVERALL WIND SPEEDS...AND A DELAY IN ANY PRECIPITATION CHANCES NEAR THE COAST UNTIL AFTER MIDNIGHT. ISOLATED SHOWERS ACROSS PENDER COUNTY SHOULD DIE A QUICK DEATH OVER THE NEXT FEW HOURS AS DRY AIR ALOFT WINS THE GAME. FARTHER INLAND WHERE BETTER MOISTURE EXISTS WITHIN THE 850-700 MB LAYER...SCATTERED SHOWERS AND EVEN A FEW THUNDERSTORMS ARE POSSIBLE NEAR AND WEST OF I-95 THROUGH THE LATE AFTERNOON. THESE SHOWERS AND STORMS WILL BECOME MORE ISOLATED AFTER SUNSET AS THE SURFACE STABILIZES AND CONVECTION WILL BE FORCED TO USE 850 MB AS A LIFTING LAYER...WITH LESS INSTABILITY AND ONLY THE INCOMING FRONT AS A CONVERGENT BOUNDARY. THE COLD FRONT ITSELF IS MAKING QUICK PROGRESS SOUTHEASTWARD THROUGH WESTERN VIRGINIA AND NORTH CAROLINA...AND SHOULD BE NEAR THE COAST AT SUNRISE FRIDAY. LOWS SHOULD FALL INTO THE 72-76 RANGE OVERNIGHT...NOT AS COOL AS ONE MIGHT THINK WITH AN INCOMING FRONT. A FEW MORE CLOUDS THAN WE SAW THIS MORNING PLUS LOW-LEVEL MOISTURE POOLED NEAR THE BOUNDARY SHOULD PREVENT TEMPS FROM FALLING TOO FAR. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... AS OF 330 PM THURSDAY...A COLD FRONT WILL SHIFT OVER THE FORECAST AREA ON FRIDAY AND WILL REMAIN THROUGH THE PERIOD.THE MOISTURE WILL INCREASE BUT A VERY TIGHT GRADIENT WILL BE SEEN WITH +2 INCH PW ALONG THE COAST TO 1.5 INCHES WEST OF INTERSTATE 95. MODELS ARE SHOWING THE BEST CONVECTION FROM 15 UTC INTO THE OVERNIGHT HOURS WITH A 50% CHANCE OF THUNDERSTORMS ESPECIALLY OVER THE EAST HALF OF THE FORECAST AREA. THE CONVECTION CHANCES WILL SLOWLY BACK TO 30 PERCENT BY LATE SATURDAY NIGHT. HIGHS WILL RANGE FROM THE MID 90S INLAND UNTIL THE CLOUD COVER AND CONVECTION BEGINNING AND TO THE UPPER 80S AT THE BEACHES. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 330 PM THURSDAY...UNSETTLED WEATHER TO START THE PERIOD WILL GIVE WAY TO WARMING TEMPERATURES THROUGH THE MIDDLE OF NEXT WEEK. STALLED COLD/STATIONARY FRONT WILL BE IN THE VICINITY SUNDAY...PROBABLY ALIGNED RIGHT ALONG OR JUST OFF THE COAST... BEFORE WASHING OUT AND DISSIPATING ON MONDAY. VERY HIGH PWATS AND SOME TROPICAL MOISTURE WILL BE LURKING JUST OFF THE COAST...SO AS THIS FRONT LIFTS BACK NORTH MONDAY AND FALLS APART...INCREASING PRECIP CHANCES WILL OVERSPREAD THE AREA FROM SE TO NW. HOWEVER... THE BULK OF THIS PRECIP IS STILL EXPECTED TO REMAIN OFFSHORE. HOWEVER...WILL CONTINUE THE MDT-CHC POP ALONG THE COAST WITH LOW- CHC INLAND FOR SUN/MON ALONG WITH TEMPS AROUND NORMAL FOR EARLY AUGUST. THEREAFTER...LARGE RIDGE ACROSS THE SOUTHERN TIER WILL EXPAND NE INTO WEDNESDAY BRINGING REDUCED PRECIP CHANCES LOCALLY...BUT WITH TEMPS RISING TO ABOVE NORMAL ONCE AGAIN. THIS HEAT MAY BE SHORT LIVED THOUGH AS A COLD FRONT IS PROGGED TO PUSH SOUTH THURSDAY...WITH VERY DEEP TROUGHING IN ITS WAKE ACROSS THE EASTERN CONUS. THIS WILL BRING COOLER TEMPS AND ONCE AGAIN INCREASED PRECIP CHANCES AT THE END OF THE PERIOD. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... AS OF 00Z...RADAR SHOWING SOME SCATTERED CONVECTION ACROSS INLAND ZONES THAT MIGHT BE IN THE VICINITY OF KLBT AND KFLO FOR THE NEXT 1-3 HOURS SO I WILL MAKE MENTION OF THIS IN TAF. SEA BREEZE FRONT MAKING STEADY PROGRESS TO THE WEST AND HELPING TO DISSIPATE THESE SHOWERS WHEN THEY INTERACT. FOR THE OVERNIGHT PERIOD EXPECT VFR CONDITIONS ACROSS THE TERMINALS WITH BEST CHANCE OF ANY PRECIPITATION OCCURRING AFTER SUNRISE WITH CONVECTION MAINLY OVER THE EASTERN HALF OF THE CWA. POST FRONTAL LIGHT NORTHERLY FLOW IS FORECAST. MODERATE CONFIDENCE THAT TERMINALS WILL STAY VFR ON FRIDAY WITH JUST A CHANCE OF CONVECTION DIRECTLY OVER A TERMINAL THROUGHOUT THE DAY. EXTENDED OUTLOOK...PREDOMINANTLY VFR THROUGH THE PERIOD WITH A SLIGHT CHANCE AFTERNOON SHRA/TSRA. BEST CHANCE SHRA/TSRA FRIDAY AND SATURDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 745 PM THURSDAY...LOW PRESSURE OFFSHORE FROM CAPE FEAR...WILL BEGIN TO GET SHUNTED TO THE N BY NE LATE THIS EVENING AND OVERNIGHT. THIS IN RESPONSE TO THE APPROACHING COLD FRONT FROM THE MAINLAND...THAT WILL SLOW ITS FORWARD PROGRESSION BY DAYBREAK AND LIKELY STALL JUST PRIOR TO MOVING OFF THE CAROLINAS MAINLAND. THIS DUE TO THE LACK OF ANY MID OR UPPER LEVEL PUSH. WINDS CIRCULATING AROUND THE LOW AND PORTIONS OF THE FA WILL GIVE WAY TO A SYNOPTIC SW-WSW FLOW WITH SPEEDS AROUND 10 KT. SIGNIFICANT SEAS WILL RUN 2 TO 3 FT...OCCASIONALLY UP TO 4 FT ESPECIALLY OFF CAPE FEAR AND CAPE ROMAINE. DOMINANT PERIODS WILL BE AROUND 7 TO 8 SECONDS...WITH A SSE PSEUDO GROUND SWELL THE DOMINANT PLAYER. PREVIOUS....................................................... AS OF 330 PM THURSDAY...LOW PRESSURE IS LOCATED A LITTLE OVER 200 MILES EAST OF BEAUFORT SOUTH CAROLINA. THIS LOW HAS BEEN BATTLING DRY AIR INPINGING ON THE CIRCULATION FROM THE NORTH. THE 12Z GFS AND NAM MODELS APPEAR FAR TOO EAGER TO ABSORB THE LOW INTO THE COLD FRONT APPROACHING FROM THE WEST TONIGHT. THE 17Z RUN OF THE RUC MODEL APPEARS MUCH MORE REASONABLE AS ITS INITIALIZED POSITION OF THE LOW IS MUCH CLOSER TO WHERE IT APPEARS ON VISIBLE SATELLITE. COMPARED TO THE NAM AND GFS THIS MEANS A SLOWER VEERING OF SURFACE WIND DIRECTIONS...LIGHTER OVERALL WIND SPEEDS...AND A DELAY IN ANY PRECIPITATION CHANCES NEAR THE COAST UNTIL LATE TONIGHT. SEAS CURRENTLY RANGE FROM 2-3 FEET INSIDE 20 MILES FROM SHORE...TO AS HIGH AS 4 FEET OUT AT THE FRYING PAN SHOALS BUOY. THE WAVE SPECTRUM IS DOMINATED BY SWELL ENERGY AT AROUND 7-8 SECONDS PERIOD. THIS SOUTHEASTERLY SWELL IS BEING GENERATED BY THE LOW OFF THE SOUTH CAROLINA COAST...AND SHOULD REMAIN THE DOMINANT WAVE SET TONIGHT. SOME OF THESE 4-FOOTERS SHOULD MAKE IT INSIDE THE COASTAL WATERS TONIGHT...ESPECIALLY NEAR CAPE FEAR. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 330 PM THURSDAY...A COLD FRONT WILL STALL ALONG THE COAST AND WINDS AREA EXPECTED TO REMAIN AT 10 KNOTS OR LESS AND DIRECTIONS WILL BE VARIABLE OVER THE PERIOD. SEA HEIGHTS ARE EXPECTED TO RANGE BETWEEN 2 AND 3 FEET WITH A FEW 4 FOOTERS AT 20 MILES OF THE COAST MAINLY FROM FRYING PAN SHOALS NORTHWARD. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 330 PM THURSDAY...WEAKENING COLD FRONT WILL DISSIPATE JUST INLAND FROM THE COASTAL WATERS SUNDAY INTO MONDAY...ALLOWING FOR BERMUDA HIGH PRESSURE TO ONCE AGAIN BECOME THE DOMINANT SYNOPTIC FEATURE. THIS WILL CREATE SW WINDS OF 10-15 KTS...WHICH WILL BE PERSISTENT WITH LITTLE FLUCTUATION THROUGH THE PERIOD. WAVE AMPLITUDES WILL INCREASE...ESPECIALLY EARLY NEXT WEEK...AS A FAIRLY SIGNIFICANT SOUTHERLY SWELL OF 5-6 FT ENTERS THE SPECTRUM AND COMBINES WITH THE SW WIND CHOP TO PRODUCE 4-5 FT SEAS MONDAY AND TUESDAY...AFTER BEING 3-4 FT ON SUNDAY. && .TIDES/COASTAL FLOODING... AS OF 300 PM FRIDAY...ONSHORE WINDS ARE PRODUCING A SMALL 0.5 TO 0.6 FOOT POSITIVE TIDAL ANOMALY AT THE BEACHES. LARGE TIDAL RANGES ASSOCIATED WITH THE FULL MOON PLUS THIS ANOMALY WILL PUSH WATER LEVELS TO WITHIN ABOUT 4 INCHES OF MINOR COASTAL FLOODING CRITERIA AT BOTH WRIGHTSVILLE BEACH AND MYRTLE BEACH THIS EVENING. NO COASTAL FLOOD ADVISORY IS PLANNED...HOWEVER ALONG THE LOWER CAPE FEAR RIVER AT DOWNTOWN WILMINGTON WHERE THE OBSERVED ANOMALY IS CLOSER TO +0.8 FEET WE SHOULD ECLIPSE MINOR FLOOD CRITERIA HERE. A COASTAL FLOOD ADVISORY HAS BEEN ISSUED FOR LOW-LYING AREAS NEAR THE RIVER BETWEEN 8-11 PM. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...COASTAL FLOOD ADVISORY UNTIL 11 PM EDT THIS EVENING FOR NCZ107. MARINE...NONE. && $$ SYNOPSIS...DRH NEAR TERM...DCH/TRA SHORT TERM...DRH LONG TERM...JDW AVIATION...MAC TIDES/COASTAL FLOODING...RJD

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