Area Forecast Discussion
Issued by NWS Wilmington, NC

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522 FXUS62 KILM 251658 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1258 PM EDT Tue Apr 25 2017 .SYNOPSIS... A slow moving storm system nearly overhead this morning, will lift northeast away from the area this afternoon through mid week. Look for slowly improving conditions, with a warming and drying trend. A weak cold front will dissipate as it moves across the area Thursday night, followed by high pressure aloft and early summer-like conditions Friday into the weekend. A few locations away from the coast, may break the 90 degree mark this weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 1136 AM Tuesday...Wrap around moisture associated with a slowly departing upper low is beginning to make inroads and bringing an uptick in mid-level moisture into the area. Local forecast soundings show a bit of convective inhibition between 4-9 KFT that will gradually be overcome as surface heating begins to increase and mid-level moisture bleeds in. As a result we may see an increase in convection in the middle to late afternoon and showers already are popping across the Bladen Lakes area situated along the eastern edge of the moisture plume diving to the SSE presently. As a result no significant changes are being made to the afternoon forecast except to fine tune pop distribution and tweak T/TD. A slight chance of a TSTM remains intact and there remains a non-zero chance of small hail with any strong shower or storm given the cold temperatures aloft, as the -20C isotherm is not much higher than 20 KFT. Low level wind speeds do not support much of a wind threat with convection but gusty winds of 30-40 mph is not out of the question with any TSTM that does develop due to downdraft CAPE values. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 330 AM Tuesday...At the start of this period, the nemesis closed low aloft, off the DELMARVA Coast, will continue to fill in as it tracks to the northeast, further away from the forecast area. It`s corresponding, captured sfc low, will also be weakening during this time-frame. Overall, in their wake, the ILM CWA will commence an extended "drying out out" period. Weak s/w ridging aloft will affect the FA thru Thu night. It`s upper ridge axis will lie overhead Thu morning, moving off the Carolina coasts by Fri daybreak. A rather expansive upper trof will have taken shape across the central U.S. by Fri morning. At the sfc, weak cyclonic NW flow will dominate the FA early Wed until the upper/sfc lows move far enough away. By late Wed thru daybreak Fri, sfc ridging from Bermuda High pressure centered well east of Florida, will extend WNW and onshore in the vicinity or south of Cape Romain, SC. Enough moisture in the low levels will be avbl for diurnally driven cu fields each day. Enough subsidence aloft will prevent the cu from growing too much in the vertical, resulting in no POPs being advertised Wed thru sunset Thu. A fading cold front will push across the FA from the west late Thu night. The front will be displaced a good distance from it`s parent low as it traverses the ILM CWA. Other than frontal dynamics, not much forcing is left for pcpn development. As a result, will include low chance pops for showers and possibly an isolated tstorm Thu night if enough instability becomes avbl. A low level SW jet will develop during Thu night into early Fri. This will keep winds active enough at the sfc to prevent widespread fog but also keep min temps on the high side. Summer time temperatures will be back across the FA with widespread max temps in the low to mid 80s Wed and mid to upper 80s Thu. Min temps will follow the general trend and run in the low 60s Wed night and the mid to upper 60s Thu night. This a consensus amongst the avbl model mos guidance. This fcst has temps that will run 10 to 15 degrees above normal by the end of this period. Normal lows/highs are in the low to mid 50s and the upper 70s respectively. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 3 PM Monday...Medium range guidance is fairly consistent with regards to the extended forecast. Longwave troughing will be in place out west with a cutoff low eventually developing with a southwest flow and strong ridging developing just off the southeast coast. At the surface it will be primarily high pressure anchored offshore. A weak front will fade away as it moves across the FA early Fri leaving a continued dry forecast. Temperature trends remain mostly intact well above normal throughout the period but moreso first half as heights fall slightly late in the period. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... As of 17Z...MVFR cigs this afternoon further improving to MVFR/VFR conditions late this aftn thru tonight. As the upper low lifts NE, away from the area this afternoon and night, improving conditions across weather parameters will occur. Will still have to contend with light to moderate showers over SE NC until 00z-01z. Patchy fog late tonight mainly along and west of I-95. Wind directions will become w to nw throughout. Wind speeds will run 10-15 kt this afternoon and drop back to 5 kt or less during this evening and overnight. Extended outlook...Possible MVFR/IFR from fog early Wed morning. VFR expected from Wednesday through Saturday. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 822 AM Tuesday...The SCA for SC has expired as seas have fallen below 6 feet for the majority of the 0-20 NM waters there, no other changes. As of 330 AM Tuesday...Low pressure just off the Grand Strand will spin slowly off to the NE today. As this surface feature pulls away, winds will become predominantly S/SW and increase back towards 15-20 kts before slowly veering to the West, and then NW tonight, while easing to around 10 kts. Seas remain high this morning thanks to a variety of wave groups, and the SCA has been extended for the NC waters through late this aftn, while expiring in the next few hours across the SC waters. Seas recently at 41013 were still near 9 ft, and 7 ft at 41004. Expect these to gradually ease through today, becoming a more uniform 3-5 ft this evening, and 2-4 ft tonight, as both the SE swell and SW wind wave begin to decay in amplitude. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 330 AM Tuesday...Improving seas and winds will continue from where the near term left off as the last affects from the departing upper and sfc lows occur early Wed with diminishing NW flow and a transition to light SSE to SSW flow by late Wed and continuing thru Thu night. This a result of sfc ridging, from Bermuda high pressure located well offshore and east of Florida, extending WNW and onshore in the vicinity of Cape Romain by and thru Thu. Wind speeds around 10 kt Wed, with 10 to 15 kt near shore Wed aftn/evening due to a weak sea breeze. Wind speeds Thu will run 10 to 15 kt, except 10-20 kt near shore Thu aftn/evening due to a moderate sea breeze. The ESE ground swell at 8 to 9 second periods, will dominate the seas spectrum Wed and for much of Thu. A low level SW jet Thu night will keep winds active thru the night resulting in 3 to 5 second period wind waves becoming more dominate. LONG TERM /FRIDAY THROUGH SATURDAY/... As of 3 PM Monday...Essentially a summertime pattern for the coastal waters as ridging from Bermuda High pressure affects the area waters thruout this time frame. South to southeast winds of 10-15 knots will prevail Friday through Saturday. Significant seas will be 2-4 feet. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory until 5 PM EDT this afternoon for AMZ250- 252. && $$ NEAR TERM...MJC SHORT TERM...DCH LONG TERM...MBB AVIATION...8 MARINE...DCH/JDW/MBB/8

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