Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 261721 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1221 PM EST Sun Feb 26 2017 .SYNOPSIS... Much cooler temperatures expected today as high pressure builds into the Carolinas. These cool temperatures will be short lived as a warm front lifts north early Tuesday. Near record high temperatures expected again by the middle of the week before a cold front crosses the area on Thursday. A return to winter like temperatures is expected for next weekend. && .NEAR TERM /THROUGH TONIGHT/...
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As of 900 AM Sunday...Once again, very little tweaking needed at this update. Latest sat imagery shows crystal blue skies across the ILM CWA not even a hint of cirrus. Winds will continue to diminish and likely will go decouple by sunset. Setting up for an excellent night of radiational cooling. Clear skies, sfc based inversion develops after sunset resulting in winds decoupling, ie. going calm and temps dropping like a jet plane in backwards thrust when landing. After highs around 60 this aftn, tonights lows will bottom in the low to mid 30s with upper 30s along the immediate coast. Much of the drop, like a waterfall, will occur during this evening.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 AM Sunday...High pressure will move farther away from the U.S. east coast Monday and Tuesday, opening up the door for subtropical warmth and humidity to return to the Carolinas. The modification will begin Monday morning as the nocturnal inversion breaks and southeasterly winds develop. Highs Monday should reach the lower 70s inland with mid to upper 60s near the beaches. The forecast has shifted somewhat for Monday night compared to 24 hours ago. While an approaching upper disturbance and low- level warm advection should still work together to develop a large zone of weak to moderate isentropic lift across the Carolinas, the quality of moisture in the incoming southerly flow is not quite as good in the current 00z model runs. In particular, large swaths of dry air at 5000-12000 ft AGL will act to reduce the areal coverage of rainfall. The isentropic lift itself will proceed much as the models showed 24 hours ago, but without nearly as much moisture being lifted and cooled to its dewpoint, the risk of rainfall has diminished. PoPs in the 30-40 percent range are currently forecast for Monday night (mainly after midnight) with lows in the mid to upper 50s. By Tuesday the same airmass we had yesterday will be back, only with higher dewpoints given its source region in the southern Bahamas. Highs could approach 80 in a few inland spots with 70s expected for all but the beaches. Surface-based instability should grow to 500- 1000 J/kg with bulk shear values increasing toward 40 kt by late afternoon. Lapse rates aloft are not that bad, and given rather low wet-bulb zero heights around 9500 feet I would not be surprised for some sort of hail threat to develop in thunderstorms. Waning instability during the evening should end the thunderstorm threat. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 300 AM Sunday...Forecast area will be solidly in the warm sector Wed with temperatures approaching 20 degrees above normal. Convection will be possible Wed afternoon given low level moisture and diurnal heating, but there will be several limiting factors. Mid level subsidence and dry air above 850 mb will be the biggest issue, but there is also a lack of forcing. A modified sea breeze may lead to some storm development across southeast NC but confidence is low. Better precip chances will be late Wed night through early Thu as strong cold front moves across the area. Frontal passage occurs Thu morning, coincident with the surface based instability minimum. However, the front and its 5h trough will provide strong lift and a healthy chance of showers and isolated thunderstorms through the first part of Thu morning. Strong cold advection develops Thu with 850 temps dropping around 10C from Thu morning to Thu evening. Highs Thu will end up well above climo, but will likely occur during the first few hours of the morning with temps steadily trending down during the day. Incoming air mass is very dry with potential for RH dipping below 30%. Temps below climo Fri and Sat with a reinforcing shot of cold air expected Fri night into Sat. && .AVIATION /17Z SUNDAY THROUGH THURSDAY/...
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As of 12Z...High confidence for VFR conditions through the forecast period. High pressure will continue to build in this morning, with weak cold air advection. Northwest flow around 10 kts will diminish by late afternoon. Do not currently have fog in the forecast, but will reevaluate conditions with the next model run. Extended Outlook...VFR. VSBY and ceilings lowered to MVFR/IFR with pcp Mon night into Tues and again with SHWRs on Wed.
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&& .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of noon Sunday...SCEC has finally been allowed to expire at noon. Ridging from the high`s center over eastern TN and KY will continue across the local waters. The center is progged to move east to the eastern Carolinas tonight and off the NC coast and offshore on Monday. With the sfc pg relaxing, winds will diminish to 10 kt or less by end of today and continuing thru the night. Wind direction may become variable in direction around 5 kt for a time late tonight due to the proximity of the high`s center nearly overhead. Significant seas will continue with their slow subsiding trend due to the ESE 10 second period ground swell taking longer to decay. Wind driven waves at 4 to 5 second periods have nearly shaved off 2 ft since mid daytime morning. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 AM Sunday...High pressure east of the Outer Banks Monday morning will move farther offshore Monday night and Tuesday. Southeasterly winds Monday should turn southerly by Tuesday in the flow between the departing high and low pressure advancing eastward across the Plains states. LONG TERM /WEDNESDAY THROUGH THURSDAY/... As of 300 AM Sunday...Southwest flow will steadily increase Wed, peaking at 20 to 25 kt in the afternoon and evening ahead of cold front approaching from the west. Front moves east across the waters Thu morning with offshore flow developing by midday. Gradient and cold advection will keep offshore flow a solid 15 kt into Thu evening before northerly winds start to weaken. Seas 3 to 4 ft Wed morning will build to 4 to 7 ft Wed evening and remain above SCA thresholds through much of Thu morning before offshore flow drops seas to 3 to 5 ft Thu afternoon and 2 to 3 ft Thu night.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...III NEAR TERM...DCH SHORT TERM...TRA LONG TERM...III AVIATION...DL

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