Area Forecast Discussion
Issued by NWS Wilmington, NC

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201 FXUS62 KILM 270723 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 323 AM EDT FRI MAY 27 2016 .SYNOPSIS...
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One last sunny and warm day today before clouds and showers increase for the weekend. Low pressure from the Bahamas will organize and approach the South Carolina coast Sunday. This low pressure will meander in the general area through the middle of next week continuing unsettled weather with slightly cooler temperatures. Although winds are not expected to be strong...periods of heavy rainfall and strong rip currents are possible throughout the holiday weekend.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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As of 3 AM Friday...Sunshine minutes today to reach the moderate to high category as subsidence aloft is injected into the western lobe of the overhead upper ridge, by the approach of the broad upper gyre hosting the tropical wave below it. A few clouds into daybreak near 6000 feet will erode following sunrise. There may be some afternoon cumulus but sea-breeze convergence is expected to remain weak today since the synoptic and sea breeze flow remain similar to northwest. Debris clouds from convection well west of the region may increase later in the day generally above 20 thousand feet. The overnight period will remain quiet and it is not until daybreak Saturday that we see significant column moisture brought onshore. Maximums for today middle and upper 80s and warmest deeper inland, minimums near 70 at the coast and middle 60s inland in light northeast wind.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/...
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As of 3 AM Friday...A consensus can be seen in the PMSL plots from the GFS/NAM/ECMWF/SREF solutions showing a 1009-1013 MB low moving near or onshore into the Charleston area sometime Sunday afternoon or evening. This consensus was used to generate pop distribution and construct the QPF layout for Saturday and Sunday. The rainfall expectation at present is 1 to 1.25 inch totals SAT/SUN for coastal SC and around a half inch on areal average across SE NC. Winds at least for now do not appear to pose a hazard concern. Convection embedded in the tropical moisture however could cause locally heavy rain because precipitable waters in excess of 2 inches will edge onshore by Saturday afternoon. Low-level winds are not strong so any TSTMS should remain below severe limits barring no enhanced low level helicity. The National Hurricane Center will be sending out a plane today to investigate the offshore system. Maximums both days near average for this time of year, low and middle 80s. Minimums will be slightly above overage due to clouds and abundant moisture.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/...
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As of 300 AM Friday...Lots of uncertainty remains in the extended as what could very well be Topical/Sub-tropical storm Bonnie drifts across the area. Other than the GFS which is a clear outlier (00z/27 guidance) - the majority of the models develop a weak closed low moving onshore in SC and then drifting slowly before lifting NE at the start of the extended. The difference in the GFS vs the other guidance is how the surface low interacts with a shortwave moving through the Great Lakes and into New England. This shortwave is the one currently across TX...and this should break down the ridge enough to allow the surface low pressure to move NE and out of the area mid-week around the offshore high. The GFS does not have this happen and therefore spins the weak low across SC through all of next week. That being said...will favor a non GFS forecast for next week. This suggests increasing rain and thunderstorm chances...mostly Mon/Tue as the weak low meanders NE across the ILM CWA. The combination of the weak low moving slowly overhead and the deep easterly tropical fetch angling into the area will produce widespread showers and thunderstorms early next week. Still uncertainty exists about QPF due to the showery nature of the precip and weakening 850mb wind/moist transport...but with PWATS around 2 inches there is at least the potential for periods of heavy rainfall. Beyond Tuesday...anticipating the slow departure of the remnants of the low pressure...the area will remain unsettled but with at least somewhat decreasing shower chances and warming temperatures as ridging begins to blossom across the SE.
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&& .AVIATION /07Z FRIDAY THROUGH TUESDAY/... As of 06Z...Potential for patchy fog near daybreak which may create marginal MVFR. Otherwise expect VFR through the valid TAF period OCNL SCT050. Increasing southeast winds to around 10 kts this taf cycle. Extended Outlook...OCNL MVFR in scattered to numerous showers, isolated TSTMS this weekend. Otherwise expect VFR. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 3 AM Thursday...Another fine marine-weather day but waves will begin to grow tonight as swell from an approaching tropical wave fans ashore, reaching 3 to 4 feet every 8-9 seconds from the SE by daybreak Saturday. As a result no advisory is expected through the near term period, but showers will begin to increase in coverage offshore, and waves will continue to grow in size into Saturday. Light southerly winds this morning will become more onshore ESE-ENE in the afternoon but no higher than 15 kt with seas holding 2-3 ft every 8-9 seconds. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 3 AM Friday...The weekend will not be ideal for offshore boating ventures as elevated seas in SE swell and scattered to numerous showers and isolated TSTMS will troll the waters. Seas 4 to 6 feet every 9 seconds accompanied by a moderate onshore chop will characterize the sea- spectrum. The National Hurricane Center is sending a plane out this afternoon to investigate the system for tropical development and potential. Mariners should remain closely briefed on the weather as there is a possibility a `tropical storm watch` may be posted. LONG TERM /MONDAY THROUGH TUESDAY/... As of 300 AM Friday...Meandering low pressure will remain the primary story this period as it moves slowly across or just inland of the coastal waters. The gradient around this feature will be weak...so wind speeds are forecast to be just around 10 kts...with a S/SE or S/SW direction both days. Wave heights will be dependent primarily on continuing 8 sec E swell from the weekend...with some 6 fters still possible Monday before falling to 3-4 ft Monday night and Tuesday. Still some uncertainty into the track and strength of this low pressure...which could impact this forecast considerably...but attm it appears the worst of the marine conditions may occur before this period.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...JDW NEAR TERM...MJC SHORT TERM...MJC LONG TERM...JDW AVIATION...MJC MARINE...MJC/JDW

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