Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 100707 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 207 AM EST Sun Dec 10 2017 .SYNOPSIS...
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Bright sunshine finally returns today and Monday with dry weather expected this week. Sunshine will bring a modest temperature rise and we will be close to normal by Tuesday. Another strong cold front will move across the area late Tuesday with Arctic air returning Tuesday night through Wednesday night. Temperatures will moderate late week. A cold front may bring a brief cool down to start the weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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As of 1000 PM Saturday...Though sunshine will abundantly return today seasonable temperatures will not. Forecast model soundings show PW values drop to just 0.25" indicative of dry air through the entire column. Northwesterly flow in the mid levels will push a thermal trough across the areas with 850mb temps bottoming out at -6C around daybreak before some weak recovery gets underway. Such chilly values should readily cap afternoon high temperatures in the 40s once again (though with sunshine and less wind today will arguably have a less raw feeling than yesterday). Wind turns more southerly at the surface tonight, a harbinger of the warming trend slated for Monday. Forecast soundings do not show a hard decoupling, but rather a deep nearly isothermal layer developing supportive of low temps within a few degrees of the freezing mark for most locales.
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&& .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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As of 300 AM Sunday...Bright sunshine will remain across the area for Mon. A deep westerly flow will develop with a low-level SW flow and this will allow temps to reach the mid 50s Mon afternoon despite below freezing temps at sunrise. We will be under the influence of warm air advection Mon night and with stronger winds aloft, we will not fully decouple and this will keep lows from dropping below the mid and upper 30s with lower 40s at the coast. Upper trough digs across the Ohio Valley Mon night and then pivots across the Southeast states, moving across the eastern Carolinas late Tue and Tue eve. This will drive a cold front across the Forecast Area. Arctic air will plunge across the region in the wake of this front, bringing a brief return to the deep freeze. Still looks like airmass will be too dry to support precipitation, but should see a period of partly cloudy skies as the front moves through with clearing overnight Tue. It will be breezy on Tue with high temps likely just about the warmest of the week, reaching the upper 50s in most locations before the arrival of much colder air. 850 mb temps will drop to minus 5 to minus 9C by daybreak Wed. As dewpoints crash into the teens late Tue night, lows will drop to the mid and upper 20s by daybreak Wed with the beaches perhaps holding onto readings near freezing.
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&& .LONG TERM /WEDNESDAY THROUGH SATURDAY/...
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As of 300 PM Saturday...Change in 850 temps from Tue to Wed is almost 15C, +3C to -11C. Highs Wed will struggle to reach mid 40s despite full sun should that verify. Next shortwave crosses the area Thu morning, again starved of moisture, and lacks any cold air. Wave exits northeast on Thu as the 5h trough starts to flatten ahead of the next, stronger shortwave. As the 5h trough amplifies to the west, deep southwest flow will develop over the southeast, pushing temps closer to climo. Duration of the return flow is brief and precipitable water values barely reach half an inch. Clouds will increase Thu night as the wave approaches and then passes early Fri morning. Not sold on any measurable precip based on moisture profiles despite the strength of the feature. Cold front trailing the wave quickly crosses the area and shifts offshore early Fri, bringing another round of cold advection to the region late Fri. Advection arrives too late to have a big impact on highs for Fri, but Fri night temperatures will drop below climo. Although this air mass does not look as cold as the one during the middle of the week, temperatures for the end of the period will still be close to 10 degrees below climo.
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&& .AVIATION /06Z SUNDAY THROUGH THURSDAY/... As of 06Z...Dry air has quickly swept into the region and cleared out cloud cover. VFR is thus expected to last through the period as high pressure builds in from the west. Extended Outlook...VFR through Thursday. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 300 AM Sunday...Cold and dry surge of air underway, keeping gradient rather tight. The surge is weakening however and so wind and waves should be abating, the latter trend aided by the increasingly offshore trajectory in the veering flow. The Advisory currently in effect has been marginal and uncertain for a while now. Given that wind and waves are still close to criteria and that dominant wave period is a choppy 6 seconds have decided to err on the side of caution and leave it as-is. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 300 AM Sunday...Benign winds and seas on Mon. Gradient will tighten Mon night and Tue ahead of a strong cold front which will move across the waters Tue eve. W to WSW winds on the order of 10 to 15 kt Mon will be WSW to SW Mon night and increase to 15 to 20 kt. WSW winds Tue will become W and increase to around 20 kt in the afternoon. The passage of the cold front will shift winds to the NW Tue eve. Winds Tue night will peak near Small Craft Advisory criteria, 20 to 25 kt. Seas will be 3 ft or less Mon, building to 3 to 5 ft Mon night and Tue and perhaps up to 4 to 6 ft Tue night as cold and dry surge intensifies, although the strong offshore component should drive seas lower near shore. LONG TERM /WEDNESDAY THROUGH THURSDAY/... As of 300 PM Saturday...Winds of 20 to 25 kt at the start of the period. Offshore component may keep seas within 20 nm of the SC coast under 6 ft, but NC nearshore waters seem likely to hit 6 ft and possibly 7 ft at times. Cold advection and gradient slowly weaken on Wed with offshore flow gradually dropping to 20 kt around midday and 15 to 20 kt by the end of the day. Seas will mimic wind speeds, slowly subsiding Wed into Wed night. Flow remains offshore Wed night, before backing to southwest Thu and starting to increase as next cold front approaches from the west. Southerly flow will increase to a solid 20 kt Thu afternoon and evening with seas increasing from around 2 ft Thu morning to 3 to 5 ft Thu evening.
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&& .ILM WATCHES/WARNINGS/ADVISORIES...
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SC...None. NC...None. MARINE...Small Craft Advisory until noon EST today for AMZ250-252-254- 256.
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&& $$ NEAR TERM...MBB SHORT TERM...RJD LONG TERM...III AVIATION...MBB

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