Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 240442 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 1242 AM EDT Mon Oct 24 2016 .SYNOPSIS... High pressure over the Southeast tonight will be pushed south by a dry cold front Monday afternoon. High pressure building in from Canada will bring cool conditions to the region for the middle of the week. Temperatures will warm late in the week as the center of the high moves offshore. Thursday night and Friday a weak cold front slowly approaching from the west may bring a slight chance of showers. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... As of 1230 AM Monday...No changes to the forecast with the latest update. Previous discussion follows: A few tweaks to temperatures based on 10 PM observations. No significant changes were made, except for some 2-3 degree upward tweaks to low temperatures along the immediate coast from central Horry County northward to Oak Island. Discussion from 730 PM follows... Surface high pressure centered along an axis from southern Georgia to coastal Mississippi will actually retrograde a bit overnight as low pressure dips southeastward through the Great Lakes region. The surface pressure gradient will tighten up across the Mid- Atlantic states while remaining slack over the Deep South within the ridge. With good radiational cooling and the boundary layer now decoupling, greater changes are occurring just above the surface where the tightening pressure gradient across the Mid-Atlantic will lead to increasing wind speeds across North Carolina and points farther northward. Wind speeds at the 975 and 950 mb levels (roughly 1000-2000 ft AGL) should increase to 25 kt across Lumberton, while remaining only 10 kt over Georgetown. This should lead to a large difference in boundary layer turbulence and the eventual depth of the nighttime radiational inversion. I`ve therefore lowered forecast low temperatures by almost 10 degrees near the Santee River from Georgetown to south of Kingstree, with lesser changes farther north. Along the south-facing coast of Brunswick County, forecast lows have actually been increased by a few degrees as the west- southwest wind should advect in heat from the still-warm ocean where sea surface temperatures remain in the 70s. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Monday afternoon temps shoot up to within a few degrees of 80 in warm advection ahead of the next cool front. This boundary moves through in the late afternoon and evening but it will be running into this bone-dry airmass so no precip. This next high does not build in as aggressively as the chilly weekend airmass did. Tuesday and Tuesday night will thus not be as cold or breezy like Saturday was. Highs should hit the low 70s and lows in the mid to upper 40s. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 300 PM Sunday...Surface high building in from the north Wed shifts off the coast Thu as cold front approaches from the west. Front is pushed east by shortwave crossing the Great Lakes Thu into Fri. Aloft weak shortwave ridge overhead Wed flattens Thu as weak troughing associated with the aforementioned Great Lakes shortwave moves east. Moisture return ahead of the front is limited, as are the dynamics and both the GFS and ECMWF solutions offer limited precip chances. Best rainfall chances will be Thu night and Fri but hard to imagine anything more than slight chc pop at this point. Front is slow to exit the area, in part due to the weakness of the 5h trough, and the surface high building in behind the front lacks cold air. Temperatures climb from a little below climo Wed to above climo Thu due to development of return flow. Temps stay above climo through the period, peaking ahead of the cold front on Fri. Downslope flow helps keep temps above climo Sat/Sun and, combined with abundant sunshine, pushes highs into the low to mid 70s. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... As of 00Z...High pressure centered to our southwest will continue to dominate the weather with nearly clear skies. Winds will decouple tonight, however little or no fog is expected. Due to the orientation of the high pressure, expect westerly winds through most of the forecast period, possibly becoming southerly along the coast with the resultant by late afternoon. Extended Outlook...VFR. && .MARINE... NEAR TERM /THROUGH TONIGHT/... As of 1230 AM Monday...No changes to the forecast with the latest update. Previous discussion follows: High pressure over the Deep South will actually retreat westward a little overnight as low pressure dives southeastward across the Great Lakes. The approach of this low should be enough to tighten the pressure gradient overnight, particularly north of Cape Fear where wind speeds (currently under 10 knots) should end up close to 20 knots late tonight! Seas currently 1 to 2 feet should build by about a foot late tonight, particularly over the North Carolina waters. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Prefrontal WSW winds to shift to NW late Monday afternoon and evening. There is no strong push of cool air/high pressure behind this boundary, in contrast to the weekend FROPA. Conditions will not need any advisory or headlines. Further veering to NE is then slated for Tuesday as the high progresses eastward, while remaining well to our north. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 300 PM Sunday...Weakening northeast flow on Wed veers to southeast Thu as the surface ridge axis shifts offshore. Approach of weak cold front Thu night and Fri leads to a period of south to southwest flow but gradient remains weak with speeds staying around 10 kt. Front pushes off the coast late in the period with offshore flow setting up Fri night. Lack of cold advection/pinched gradient will keep speeds under 10 kt. Seas 2 to 3 ft Wed drop to around 2 ft Thu and Fri. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...III NEAR TERM...REK/TRA SHORT TERM...MBB LONG TERM...III AVIATION...DL MARINE...REK/TRA/III/MBB is the U.S. government's official web portal to all federal, state and local government web resources and services.