Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 200814 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 414 AM EDT Sun May 20 2018 .SYNOPSIS... Scattered showers and thunderstorms can be expected much of the upcoming week, as humid air of tropical origin remains across the region. Rain chances will increase late Wednesday into Thursday, as a cold front slowly crosses the coast. High pressure to the north, may bring a brief drying trend Friday and Saturday. && .NEAR TERM /THROUGH TONIGHT/...
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As of 414 AM Sunday...The tropical moisture connection continues to stream up from the the south around the western periphery of Atlantic ridge, but the ridge will begin to exert itself pushing westward through today as shortwave and upper level jet lifts off to the north. Initially a narrow plume will remain aligned up from the Grand Strand area up into NC inland from the coast this morning, but this will get nudged inland and farther west through today. Therefore places closer to the I-95 corridor this morning will remain quiet, but should see a better chc of shwrs/iso tstms this afternoon before much of the area experiences a lull in pcp later this afternoon. Without any mid to upper level support, showers should remain less intense today, with plenty of clouds remaining. Pcp water plume much narrower this morning aligned right along the SC/NC coast with values up over 2 inches. Inland closer to I-95 corridor, the pcp water values were near 1.5 inches this morning, but as ridge nudges westward, so will the moisture and, although it diminishes slightly tonight, it looks like it will remain over the area. Overall expect scattered to numerous showers and isolated thunderstorms, with greater chc along the coast through this morning and overnight tonight and greater chc inland this aftn. The steering flow will weaken this afternoon and therefore any thunderstorms that develop will be slower to move and could produce some ponding of water or flooding of low lying or flood prone areas in heavier downpours. Breaks in the clouds this morning inland will jumpstart temps and should see temps closer to mid 80s for highs while closer to the coast should be closer to 80. Tonight will run on the warm side once again up near 70.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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As of 345 AM Sunday...Tropical plume reflected in model PWAT still meandering in variable orientations across the area due to Bermuda High landward intrusion Monday afternoon and evening. Sensible weather impacts may not be vastly different however, expect perhaps the potential for rain-loading or rain-rates, as enough moisture will remain present in concert with May warmth, to generate at least scattered showers and isolated TSTMS. A rebound in column moisture Tuesday may make this the wettest day of the 2. Similarities prevail in rain trends as we have seen recently, ocean convection in the morning near the coast and Cape Fear, with inland afternoon convection spawned from diurnal warming across interior NE SC and SE NC. MLCAPE/MUCAPE plots this period warrant TSTMS isolated in coverage both days. Daytime highs will run close to climatology, but minimums are apt to run well above normal due to cloud cover and elevated moisture of tropical origin, hindering radiational cooling significantly.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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As of 300 PM Saturday...Guidance differs considerably in the extended with how much rain may fall during the middle of the week, leading to lowered confidence in this part of the forecast. The GFS seems to be the wettest Wed-Thu, while the CMC/ECM are much drier across the Carolinas. The synoptic setup is comparable through each model, with the key difference being the timing and duration of moisture return as model PWATs vary. The GFS may be a bit too wet, but deserves at least some credence due to the pattern remaining similar to the past week, and the moisture tap from the tropics remaining in place. Will maintain CHC POP Wed- Thu, with Tue likely being the driest of the 3, and Thursday potentially the wettest thanks to a cold front which will drop into the region and serve as a focus for convection. Regardless of how many showers develop, there will be a good chance for showers/iso tstms each day Wed-Thu with temps slightly above climo for highs, and well above for lows. Front will weaken and dissipate friday which should lead to lowered POP chances as high pressure tries to build into the region for at least one day. However, this drier air may again be short-lived. All extended models suggest a low pressure of tropical origin will develop near the Caribbean and move slowly in that region. This will again send a plume of tropical moisture towards the Carolinas bringing a return to unsettled and humid conditions with continued slightly above normal temperatures.
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&& .AVIATION /07Z SUNDAY THROUGH THURSDAY/... s of 06Z...Continuous plume of tropical moisture streaming up from the south into the area. The plume has narrowed and oriented itself right up through CRE just east of MYR. Have continued to show tempo groups for mainly MVFR ceilings and vsbys in SHRA. Winds will hold up out of the south overnight across coastal terminals and therefore will include more in the way of stratus rather than fog. Inland TAF sites will see a lighter wind and therefore have included potential for MVFR to IFR vsbys in fog and some stratus as well. Potential for on and offer showers will continue through today, but moisture profiles show clouds thinning out inland, with main layer of moisture between 15k and 20k this afternoon. Can not rule out possible MVFR in aftn convection, but expect better chc of VFR inland. Extended Outlook...Periods of MVFR/IFR cigs/vsbys associated with tropical type showers and tstorms through the period. Activity will be more numerous along the coast pre-dawn hours thru mid-morning hours each day, then translate to the inland terminals midday-early evening. Possible break in the action on Mon, but rain returning Tue and Wed. Finally an air mass change on Thu. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 414 AM Sunday...Southerly flow 10 to 15 kts will gust up near 20 kts as local waters remain on the western periphery of the Bermuda High through tonight. Seas will drop below 6 ft by noon today as winds let up a bit and become slightly more S-SW as Bermuda High nudges westward. Seas will be down to 3 to 5 ft this afternoon, subsiding slowly into Monday. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 345 AM Sunday...NO SCA flags expected this period, but marine conditions will not be smooth. Occasional 20 kt SW gusts this period and generally 4 foot seas to prevail in 8 seconds wave periods from the SE, co-mingled with moderate southerly chop. Scattered showers and isolated TSTMS can be expected, and radar updates are encouraged before heading out. Out side of synoptic 20 kt gusts, and shower/TSTM wind gusts, expect SW winds 12-17 kt most of the time. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 300 PM Saturday...Continued high pressure offshore will drive S/SW winds of 10-15 kts across the waters Wed. Early on Thu, a weak front will drop into the area turning winds to the W/NW Thu morning, before this front dissipate leaving a weak gradient and variable winds through the end of the period. Seas of 3-4 ft will continue Wed thanks to a SE swell and SW wind wave. However, as the winds ease and become variable Thursday at the same time the swell begins to deamplify, wave heights will drop to around 2 ft late.
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&& .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...None. NC...None. MARINE...Small Craft Advisory until noon EDT today for AMZ250-252-254-256.
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&& $$ SYNOPSIS...MJC NEAR TERM...RGZ SHORT TERM...MJC LONG TERM...JDW AVIATION...RGZ

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