textproduct: NWS Wilmington

SYNOPSIS

Dry high pressure and near-seasonable weather will continue through tomorrow. Another frontal system will affect the area around midweek with above-normal temperatures and low rain chances on Tuesday and Wednesday falling to well-below normal for Thursday through Saturday amidst very dry air.

NEAR TERM /THROUGH MONDAY/

Expect mainly clear/sunny skies through the near term period with high pressure in control of area weather. Lows tonight will fall to the low to mid 40s with highs Monday generally between 65 and 70.

SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/

High pressure will shift increasingly offshore of the Mid-Atlantic coast through Monday night as mid-upper ridging moves eastward ahead of an approaching trough. With easterly winds turning southeasterly over Monday night, expect morning lows on Tuesday to range from the mid-upper 40s inland to the low-mid 50s along the coast. A coastal surface trough is expected to develop as the surface high departs with a plume of moisture and weak isentropic ascent arriving along the 290-295K surfaces during the day on Tuesday. This should result in mostly cloudy skies through much or all of the day. Despite mostly cloudy skies, the surface trough is expected to push inland with winds turning southerly behind it, boosting temps into the low- mid 70s. Isolated light rain showers are possible as very weak instability either develops due to surface heating or arrives in an elevated layer during the afternoon. Either way, the shallow depth of the moisture (i.e., existing primarily below 800mb) will limit any shower's intensity.

Meanwhile, the approaching mid-upper trough will drive a cold front across the Mississippi Valley on Tuesday with this front crossing the Appalachians over Tuesday night into Wednesday morning before slowing down. Shortwave impulses ahead of the trough should lead to the Gulf Stream waters becoming convectively-active during Tuesday night, with southwest winds aloft helping to keep most or all of this activity away from Cape Fear. However, as the surface cold front draws nearer from the west and slows down, weakening upper support and subsequently weak surface convergence should support a decaying band of showers making it into the forecast area, mainly during Wednesday afternoon. Deep-layer southwest flow in the warm sector should support a mix of clouds and sun with high temps reaching well-above normal and probably higher than is currently advertised (mid-upper 70s), with some areas likely to eclipse 80F if sky cover permits.

Daytime heating of a relatively moist air mass (e.g., low to perhaps mid-60s dew points with pwats around 1.25-1.5") should yield somewhere in the range of 250-750 J/kg of SBCAPE, so isolated showers and thunderstorms can still develop ahead of this front as it crosses the area during the afternoon and evening. While effective shear magnitudes around 40-45 kts could support a gusty wind threat, forecast soundings indicate multiple layers of dry air through the troposphere which will likely choke updrafts substantially and keep most storms weak, except for perhaps one or two.

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

The cold front should move offshore by midnight Thursday with breezy northwest winds taking over behind it, causing a rapid drop in temperatures which should bottom out in the 40s by sunrise Thursday. Strong cold and dry advection will continue through Friday as high pressure with a long fetch into western Canada builds in while a strong closed low wraps up over southern Ontario and shifts across Quebec through Friday, resulting in well-below-normal highs in the 50s. Pwats should drop to around 0.25" on Thursday as very dry air and deep-layer subsidence take over, reflected by dew points dropping well into the 20s or even into the teens. Overnight lows Thursday night and Friday night are forecast to dip to near or below freezing, with winds being a limiting factor in how cold it gets on Thursday night while Friday night looks like a much better setup for a widespread freeze. Temperatures begin to recover on Saturday and Sunday as the surface high responsible for this air mass shifts to the mid- Atlantic coast and offshore, setting up a surface wedge east of the Appalachians ahead of the next storm system.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

VFR conditions are expected through the valid taf period. Winds are a little more problematic due to the weak pressure gradient over the area. Winds have gone SE-S along the Grand Strand due to sea breeze effects while elsewhere winds are N to NW. While some variability in direction remains possible along the coast this afternoon, expect winds to become nearly calm after sunset. After sunrise Monday, light NE winds are expected.

Extended Forecast...VFR outside of some morning fog during the middle of the week. The next chance for rain arrives Wednesday and Thursday with a cold front.

MARINE

Through Monday...N to NE winds invof 10 KT this afternoon will become N to NW overnight before veering to the NE to E by late in the day Monday. Seas will run 2 to 3 FT but should settle to about 2 feet by Monday afternoon.

Monday night through Thursday... Surface high pressure will shift increasingly offshore of the Mid-Atlantic coast over Monday night, causing winds to veer from ENE to SE. A coastal trough shifting inland will result in winds veering further to southerly during the day on Tuesday with speeds around 10kts. Ahead of an approaching cold front, winds increase to around 15 kts and veer to southwesterly for Tuesday night through Wednesday, with the frontal passage over Wednesday night turning the winds to northwesterly for Thursday and pushing winds up to around 15-20 kts. Seas will gradually increase from 1-3 ft on Tuesday to 2-4 ft on Wednesday before subsiding back to 1-3 ft on Thursday. The primary contributor to the wave spectrum will be wind waves with a period around 3-5 sec.

ILM WATCHES/WARNINGS/ADVISORIES

NC...None. SC...None. MARINE...None.