Area Forecast Discussion
Issued by NWS Wilmington, NC

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717 FXUS62 KILM 180726 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 326 AM EDT Wed Apr 18 2018 .SYNOPSIS... High pressure will move from the Gulf of Mexico to Atlantic through today, and warm southwesterly flow will develop across the area. A dry cold front will move across the area Thursday night, followed by high pressure Friday and Saturday. A low pressure system will move across the Gulf Coast states and bring increasing chances of rain late Sunday into early next week. && .NEAR TERM /THROUGH TONIGHT/... As of 300 AM Wednesday...A cold front resides just to the north this morning and will make little progress to the south as a strong west to southwest flow develops or actually intensifies later today. In fact the warm flow is already keeping overnight temperatures elevated across most of the area and in some cases readings have increased. With little in the way of cloud cover expected it will be a warm and blustery day as deep mixing will allow winds of 20-30 MPH with higher gusts to develop. With such a warm start, this usually portends to max temperatures exceeding the warmest guidance and the forecast has been adjusted to reflect this. Expect lower 80s along the coast with middle 80s inland. Only the beaches should remain coolish as the sea breeze should have difficulty penetrating inland. Tonight will remain blustery and on the warm side as well under mostly clear skies. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 300 AM Wednesday...A very warm Thursday will give way to much cooler temperatures Friday, but lots of sunshine is expected through the end of the week. Period begins with residual mid-level ridging and a warm sector regime across the eastern Carolinas. Although this airmass is narrow, temps are forecst to climb quickly Thursday to around 80 most of the area. The exception will be along the coast thanks to a sea breeze and onshore southerly flow, and far NW zones which will experience slightly earlier cloud increase with the cold front. This front will be driven down across the CWA late on Thursday in response to a vorticity impulse rotating through the amplifying eastern trough. Some guidance does paint some light QPF Thursday evening, but forecast soundings appear too dry for any rainfall and will instead show increasing clouds, especially NC zones, but keep POP silent. CAA is strong behind this front, and 850mb temps plummet from near +14C to around +2C by Friday morning, so after an above normal day, mins by Friday morning will likely fall to below climo, low to mid 40s, with gusty winds. In fact, winds both ahead of, and behind, this front will be strong, gusts up to 30 mph are likely from the SW Thursday aftn, remaining up to 20 mph from the NW Thursday night. On Friday, surface high across the Great Lakes expands SE, and although temp advection will become neutral and sunshine abundant, highs are forecast to climb only into the mid 60s. The airmass advecting into the region Friday is very dry, PWATs are forecast to drop to around 0.2 inches which would be near or below the all-time lowest for the date according to SPC sounding climatology for MHX. This suggests that as winds ease Friday night, good radiational cooling will occur, and lows could drop into the upper 30s in some spots, low 40s elsewhere. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 300 PM Tuesday...Broad surface high pressure over the Great Lakes will extend across the area, resulting in cool and dry northerly flow, which will veer to the northeast by Saturday. A closed mid-level low and associated surface system will slowly drift across the Gulf Coast states Sunday through Tuesday, and bring increasing chances of rain late in the weekend and into early next week. The GFS and ECMWF keep the bulk of the moisture and upper-level diffluence just south of the forecast area, however confidence is somewhat low in how this will ultimately evolve, as there is some suggestion in the models that it may become cutoff and slow or stall over southern Georgia or the Florida Panhandle by Tuesday. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... As of 06Z...VFR conditions expected through the period. The main issue will be strong winds, which will take off just past daybreak with deep mixing. Most sites will see southwest winds of 15-20 knots sustained with gusts exceeding 25 knots moreso inland. I also maintained the low level wind shear at all sites through the remainder of the overnight hours. Extended outlook...VFR. && .MARINE... NEAR TERM /THROUGH WEDNESDAY/... As of 300 AM Wednesday...Winds and seas teasing small craft criteria this morning mostly across the outermost waters. The trend should remain steady for the next few hours before elements ramp up later this morning as a strong southwest flow intensifies. Will maintain the start time to the advisory at 1 PM this afternoon. The southwest flow of 15-20 knots will develop and actually increase a bit this evening before ticking down slightly by early Thursday morning. Significant seas will just eclipse the six foot threshold for the advisory but guidance doesn`t show seas advancing much beyond that point. SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... As of 300 AM Wednesday...Small Craft Advisory conditions will be ongoing to start the period Thursday as a cold front approaches from the NW. This leaves SW winds of 20-25 kts across the waters the first half of Thursday, followed by a rapid wind shift to the N/NW post-FROPA Thursday night. A brief reprieve in wind speeds is likely during the actual frontal passage, but otherwise speeds will remain 20-25 kts regardless of direction, and other than a small window of sub-SCA conditions, a renewed SCA will be likely Thursday night. Winds will ease rapidly during Friday as high pressure builds in from the NW behind the cold front, allowing speeds to drop to around 10 kts late Friday and Friday night, with direction veering slowly to the NE. Highest seas are expected Thursday when 4-6 ft will be common, and even with the continued elevated wind speeds post cold front, the offshore direction and more limited fetch will keep wave heights to 3-5 ft into Friday morning. Seas then become more uniformly around 2 ft as the winds ease through the remainder of the period. LONG TERM /SATURDAY THROUGH SUNDAY/... As of 300 PM Tuesday...Surface high pressure will build across the Great Lakes Friday and Saturday, and produce northeast flow across the waters both days. The high will weaken and extend across the DelMarVa peninsula Saturday night into Sunday, and as a result winds will veer towards the east during that time. Winds Friday morning will start off 15-20 kt, but diminish by midday as the gradient weakens, and the direction may become somewhat variable at times. It will begin to tighten up again Sunday afternoon as low pressure slides across the Gulf Coast states. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...Small Craft Advisory from 1 PM this afternoon to 6 PM EDT Thursday for AMZ250-252-254-256. && $$ SYNOPSIS...JDW NEAR TERM...SHK SHORT TERM...JDW LONG TERM...CRM AVIATION...SHK MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.