Area Forecast Discussion
Issued by NWS Wilmington, NC

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000 FXUS62 KILM 092333 AFDILM Area Forecast Discussion National Weather Service Wilmington NC 633 PM EST Fri Dec 9 2016 .SYNOPSIS...
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Arctic high pressure will bring in the coldest temperatures of the season tonight. A warming trend will begin Sunday and Monday. A cold front will approach from the Plains and will move into the area Tuesday,remaining in the area through Wednesday before a second stronger cold front will bring below normal temperatures back to the area Thursday and Friday.
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&& .NEAR TERM /THROUGH SATURDAY/...
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As of 630 PM Friday...After highs only in the mid 40s today under full sunshine, the coldest night of the 2016-2017 winter is unfolding. By daybreak lows should reach 21-25 for most areas away from the barrier islands and immediate coast. There is still some uncertainty about how strong the radiational inversion will become tonight with 12-18 knot winds blowing just off the surface, and rather extreme sensible heat flux from the soil into the boundary layer due to relatively warm soil temps. Surface high pressure ridging across the Dakotas and into Tennessee will build into the Carolinas overnight. 850 mb temps of -4C to -6C could moderate a bit overnight not due to warm advection, but due to a lowering of the subsidence inversion aloft. All this spells crystal clear skies overnight. The last time temperatures were as cold as we`re forecasting was February 14, 2016 when lower 20s occurred in most locations.
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&& .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
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As of 300 PM Friday...The germane weather streaming headline this period reads `Frigid Sunday Morning, Chance of Rain Sunday Night and Early Monday`. Arctic high pressure entrenched over the region dawn Sunday will migrate offshore Sunday afternoon. Height falls aloft co-joined with a tenacious surface wedge will result in coastal trough formation just off the beaches. The associated low-level convergence will set off a few showers as the trough impinges the coast and coastal interior Sunday afternoon and night. The best chance of rain being Sunday late night as the trough sharpens and the moisture advection accumulates. Warm air advection will raise temperatures well above the threat of frozen pcpn, but the evaporative cooling could keep maximums Sunday below guidance values.
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&& .LONG TERM /MONDAY THROUGH FRIDAY/...
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AS OF 300 PM Friday...A comparison of the 500 mb flow between the GFS and ECMWF both are vary similar with zonal west- southwesterly flow over the southeast United States. In the lower levels the models are showing return flow from the south and southeast and the tail end of a coastal trough that had developed the the south a few days earlier. In the larger synoptic flow cold front from the plains is expect to move across the forecast area late Monday night into early Tuesday. Both the 12 UTC ECMWF and GFS are showing the cold front moving off the coast and stalling to the south and east of the area. Both are indicating that the surface low will now form a bit farther off the coast. Uncertainty is high on the fronts final location. There will be a chance of showers through Wednesday with a lull expected Monday night. QPF values are not expected to be extreme with this event. A second cold front will push quickly through the forecast area late Tuesday into Wednesday morning with another shot of colder air later Thursday into Friday.
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&& .AVIATION /23Z FRIDAY THROUGH WEDNESDAY/... As of 00Z...High confidence in VFR through the valid period. High pressure edging in from the west will become oriented overhead on Saturday. Decent radiational cooling conditions overnight. May go calm around 06Z. Northeast flow on Saturday, mainly below 10 kts. Extended Outlook...Showers possible Mon-Wed. Otherwise VFR. && .MARINE...
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NEAR TERM /THROUGH TONIGHT/... As of 630 PM Friday...Arctic high pressure ridging southeastward will cover the Carolinas by late tonight. A relatively tight pressure gradient ahead of this high will maintain northerly winds at 15 to occasionally 18 knots this evening, diminishing to 10-15 kt overnight. Seas currently 2-4 feet (highest near Cape Fear) will diminish to 2-3 feet overnight. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 300 PM Friday...Main marine headline this weekend` Cold but no Advisories expected Saturday, Deteriorating late Sunday`. As high pressure nearly overhead Saturday migrates off the mid- atlantic coast Sunday, a coastal trough will form near the Carolinas coast. Due to increasing winds moreso east of the 20NM zone, waves will build notably Sunday night to 4-6 feet and a Small Craft Advisory is very possible then. This will be joined by occasional rain showers reducing VSBY to 2-4 NM. In addition to this, its possible the warm moist over the chilly inshore waters could spur a bit of marine fog late Sunday night into early Monday. LONG TERM /MONDAY THROUGH WEDNESDAY/... As of 300 PM Friday...South-southwest winds of 10 to 15 knots will start long term marine forecast ahead of a cold front that will push off the coast late Monday and stall near or just south and east of the coastal waters on Tuesday. Winds to the west of the will be from the west and west-northwest at this time winds speeds are expected to remain below 20 knots. No small craft condtions are expected.
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&& .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...DRH/TRA NEAR TERM...TRA SHORT TERM...MJC LONG TERM...DRH AVIATION...DL

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