Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 170559 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1259 AM EST Fri Feb 17 2017 .SYNOPSIS... High pressure will reach across the Carolinas as it moves by to the south through early Saturday. A fair day Saturday may be followed by a chance of rain Saturday night into early Sunday. High pressure will build in Sunday afternoon through Tuesday. A chance of rain will return to the area the middle of next week as a storm system moves across the Southeast. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... As of 930 PM Thursday...Surface high pressure centered along the central Gulf Coast will move into southern Georgia by daybreak Friday. Surface winds are already calm inland from the beaches, and this would set the stage for excellent radiational cooling if it weren`t for mid and upper level clouds advecting in from the northwest. These clouds are rooted in a stream of moisture up above 600 mb with the flow there sculpted by a pair of shortwaves that will cross Virginia and northeastern North Carolina late tonight. Models show the southern edge of the upper level moisture getting down to around the NC/SC state line overnight. For this reason I have tweaked sky cover up by 10-20 percent across Southeastern North Carolina overnight with minor increases in forecast temperatures as well. No changes are being made across northeastern South Carolina where clearer skies and better radiational cooling conditions should prevail. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Mid level trough exits to the east Fri, replaced by building 5h ridge and increasing heights. Height increase is accompanied by development of low level return flow as surface high shifts off the east coast of FL. Both will work to push temperatures Fri through Sat above climo with highs well into the 60s on Fri and likely above 70 on Sat. Forecast soundings show subsidence inversion in place Fri and Sat, keeping the region dry and free of cloud cover into Sat afternoon. Later Sat increasing upper level moisture ahead of the next system will manifest as afternoon cirrus. Weak southern stream shortwave moving east along the Gulf coast Sat will pass just south of the area Sat night into Sun, spreading cloud cover and some light precip over the area. As this feature is not connected to the northern stream there will not be much, if any cold air behind it. Cloud cover and south then west winds Sat night will keep lows well above climo. Any rainfall Sat night is likely to be light with limited qpf. Precipitable water values remain under 1 inch for the event and the weak nature of the system does not offer much in the way of dynamics. The nocturnal timings also ensure available instability will be minimal. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 PM Thursday...Shortwave and associated sfc low will be tracking over and off the coast through Sunday morning with deeper NW flow developing as high pressure builds in from the NW through the afternoon. There may be some lingering clouds early morning but overall expect clearing skies and dry weather late Sunday through Tuesday as high pressure builds over the Carolinas. As for temps, recovery will be less than other days, but it will start off milder due to increased cloud cover Sat night and will rebound into the mid 60s most places. Also, the ridge will build in quickly behind this shortwave trough with increasing heights through Sun aftn. High pressure will build in from the west late Sun into Mon as ridge builds up the southeast coast in the mid to upper levels. This will produce plenty of dry air and subsidence with warming temps reaching up into the 70s on Monday with bright sunshine. By late Mon into Tues high pressure pushes down from Canada giving a shot of slightly cooler and drier air Mon night into Tues. This high will extend in from the north as it shifts east through Tues. Therefore winds will shift around from the N to the E by late Tues. This will also produce a cooler on shore flow. Overall expect a slightly cooler day in general on Tues with temps in the mid to upper 60s most places. The high will shift off the coast on Wed leaving a warmer and moister return flow with temps reaching back into the 70s. Should see some increasing clouds on Wed as low pressure system tracks along the Gulf coast increasing pcp chances for Wed night into Thurs. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/...
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As of 06Z...VFR conditions thruout this 24 hr TAF cycle. Weak vort aloft within NW flow aloft, will pass bye just north of the terminals and off the NC Coast early this morning. SCT to BKN thin to opaque cirrus will accompany it. Otherwise, skies mainly SKC there-after. Weak pressure pattern across the area this morning as weak ridging extends from Florida. Looking at WNW to NW less than 5 kt becoming variable or even going calm for a few hrs early this morning. Some slight tightening of the sfc pg as the sfc high moves east and offshore from Florida. Winds will become SSW to SW around 10 kt across all terminals by midday and continuing thru the aftn, then dropping back to around 5 kt after sunset. EXTENDED OUTLOOK...Primarily VFR. Possible MVFR/IFR conditions in showers Sat night thru early Sun due to the passage of a weak low pressure system.
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&& .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 930 PM Thursday...High pressure centered over the central Gulf Coast will move into southern Georgia by daybreak Friday. Northwest winds will gradually die down overnight and turn more northerly with time. Spectral wave plots show seas are an equal mix of 9-second easterly swell and 4-second wind wave. Both wave components should die away overnight with seas falling from the currently 2-4 feet (highest near Cape Fear) to 1-2 feet late. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...High pressure centered south of the are Fri morning will shift east during the day with light northerly winds backing to southwest in the afternoon. Gradient becomes a little more defined as the high moves east and southwest flow increases slightly. Diurnal increases in southwest flow later Fri and again Sat are likely with winds peaking at a solid 15 kt each afternoon. Shortwave passes to the south Sat night increasing rain chances but lack of a well defined surface feature minimizes any increase in winds with only a shift to a more offshore direction late in the period following passage of weak surface wave. Seas around 2 ft on Fri build to 2 to 3 ft late in response to slight increase in speeds late in the LONG TERM /SUNDAY THROUGH TUESDAY/... As of 300 PM Thursday...Winds will shift to the NW through Sun morning as as shortwave and associated surface low exit off to the east. As high pressure builds in from the west the winds will shift to a more northerly direction through late Sunday, but will remain 10 kts or less. By Monday a stronger area of high pressure will build down from Canada with a decent N-NE surge through the day. May see winds off shore reach up to 15 kts. The winds will also come around to a more NE to E direction by late Tues into Wed as the high to the north moves off the coast. Overall expect seas to be lowest Sun morning, less than 3 ft, with an increase through Monday up to 4 ft or so in outer waters. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...TRA NEAR TERM...TRA SHORT TERM...III LONG TERM...RGZ AVIATION...DCH

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