Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 180524 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 124 AM EDT Wed Apr 18 2018 .SYNOPSIS... High pressure will move from the Gulf of Mexico to Atlantic on Wednesday, 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 /UNTIL 6 AM THIS MORNING/... As of 1012 PM Tuesday...Low-level jet taking off now, 55 kt at 2000 feet in recent VWP returns, while on local runways, 6-9 kt inland and 8-15 kt by the coast. GOES-E nighttime channels show clear skies about the region, and the blustery off shore wind flow will maintain cloudless, and fogless conditions overnight, aside from only pieces and strands of cirrus moisture. As of 300 PM Tuesday...High pressure across the Gulf of Mexico will move east and reach the Florida peninsula this eve before moving into the Atlantic on Wed. A very weak shortwave skirting by to our N may bring a bit more cloudiness late tonight and into Wed, mainly across northern areas. There may also be some clouds associated with a strengthening seabreeze boundary Wed afternoon and eve. Otherwise, skies will be clear this period. We will be under the influence of warm air advection this period. 850 mb temps will continue to warm, peaking in the 12 to 16C range Wed. Lows tonight are expected to be in the upper 40s and lower 50s, with the coolest locations in the mid 40s. Highs on Wed will be above normal, lower 80s with upper 70s nearer to the coast. The beaches will be no higher than the mid 70s and with the prevailing SW flow, southernmost New Hanover and coastal Brunswick counties may not get above the lower 70s. Still a rather tight pressure gradient in place through Wed with low pressure across the Northeast states and high pressure to our S and winds to 40 to 50 kt at 5-6 kft. This will bring winds at the surface to 15 to 25 mph with gusts up to 25 to 30 mph with a few gusts above 30 mph possible. Afternoon relative humidity Wed will be as low as 25 to 30 percent inland. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... As of 300 PM Tuesday...Dry period on tap with one area of high pressure yielding its control over the region to another. Mid level pattern remains flat, preventing any moisture return ahead of a dry cold front expected to cross the area on Thu. Low level warm advection will push temperatures above climo Wed night and Thu. Westerly flow aloft helps maintain deep dry air, precipitable water stays well below an inch on Thu, while strong inversion based around 7k ft prevents any upward motion. Cold advection develops in the wake of the front Thu night with temps dropping into the upper 30s to lower 40s by Fri morning. Main concern during the period will continue to be very dry and windy conditions coupled with above normal temperatures. On Thu sustained wind speeds will approach 20 kt with relative humidity potentially dipping into the 20 percent range. Also a little worried about nighttime humidity recovery Wed night. Currently forecast brings humidity well into the 70% range. Would not be surprised to see values much lower in some areas, especially given breezy conditions expected Wed night. && .LONG TERM /FRIDAY THROUGH TUESDAY/... As of 300 PM Tuesday...Mid/upper level trough will shift off the coast Friday. 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 /06Z WEDNESDAY THROUGH SUNDAY/...
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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.
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&& .MARINE... NEAR TERM /THROUGH WEDNESDAY/... As of 1012 PM Tuesday...Marine Weather Statement needed, to address low water levels occurring with the overnight low tide, no changes otherwise. Outer waters will occasionally see 25 kt gusts overnight. As of 300 PM Tuesday...A Small Craft Advisory is in effect beginning early Wed afternoon. Conditions will only be just below Small Craft Should Exercise Caution late this afternoon and tonight and will cap at 15 to 20 kt. The strongest winds this period will be 20 to 25 kt later Wed afternoon. The wind direction will be SW through the period. Seas will be 3 to 4 ft through Wed morning, building to 4 to 5 ft Wed afternoon. Water levels may drop below minus 1 ft MLLW and as low as near minus 2 ft MLLW around low tide, overnight and again Wed afternoon. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... As of 300 PM Tuesday...Surface high off the southeast coast Wed night and Thu will be replaced by Canadian high Thu night following the passage of a strong cold front. Ahead of the front the pinched gradient Wed night will continue southwest flow 20 to 25 kt into Thu with seas running 4 to 7 ft. Front moves offshore and across the waters later Thu with strong offshore flow developing for Thu night. Speeds may drop under 20 kt late Thu or Thu night but there remains potential for the SCA (which currently runs into Thu afternoon) to be extended into Thu eve/night. Offshore direction will knock seas from 4 to 7 ft midday Thu to 3 to 5 ft late Thu or Thu night. LONG TERM /FRIDAY 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...
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SC...None. NC...None. MARINE...Small Craft Advisory from 1 PM this afternoon to 6 PM EDT Thursday for AMZ250-252-254-256.
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&& $$ SYNOPSIS...CRM NEAR TERM...RJD SHORT TERM...III LONG TERM...CRM AVIATION...SHK MARINE...

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