Area NWS Forecast Discussion
958
FXUS62 KILM 291513
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1013 AM EST Sun Nov 29 2020

.SYNOPSIS...
Seasonably cool high pressure with variable clouds will maintain
quiet weather through early today. Intensifying low pressure
will approach later today into Monday, leading to moderate to
heavy rain and a marginal chance of severe weather. Much colder
and drier air will follow for much of next week.

&&

.UPDATE...
Latest radar images from the Southeast suggest the weak
stationary front that was off the northeast FL coast this
morning may be starting to drift north. This feature will slowly
spread showers over the forecast area mid-afternoon into early
evening. Overall not much change from previous forecast
thinking with the only problem down to timing the arrival of
the rain.

&&

.NEAR TERM /THROUGH MONDAY/...
Latest sfc analysis shows 1023 mb high pressure centered over the
DELMARVA and 1011 mb low pressure developing over the NW Gulf of
Mexico. Patchy fog continues across the area early this morning, but
it should continue to diminish over the next few hours as calm winds
become light out of the NE. Focus for the remainder of the day will
be on the aforementioned sfc low and associated southern stream mid-
level trough. These features push ENE today, as rain chances
increase from SW to NE over the area especially late in the day as
WAA/isentropic lift increase. Best chance for rain (categorical PoPs
everywhere) arrives this evening as the highest deep moisture
advects into the area in conjunction with both low- and mid-level
forcing for ascent. For tonight into early Monday, SPC has
highlighted eastern areas in a Slight Risk for severe storms and
western areas in a Marginal Risk. The main threats are damaging wind
gusts and isolated tornadoes. Timing is not optimal and instability
will be weak, but with very large shear and helicity values, areas
closer to the coast will have a decent chance for severe wx should
even just a few hundred CAPE form. A bit of dry slotting late
tonight may allow for a break in the rain, before one final push of
precip mid/late morning Mon, paving way for a dry aftn as a cold
front pushes offshore.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
A big cool down will occur Mon night into Tues with freezing
overnight temps into midweek. A strong cold front will be
exiting farther off the coast Mon evening as deep mid to upper
low follows behind, crossing the Great Lakes and lifting off to
the northeast through Tues night. A stiff westerly flow in the
lower levels will advect plenty of dry and cool air into the
Carolinas as high pressure migrates eastward across the South.
Sounding data and moisture profiles show deep column of dry air
with only a bit of lingering moisture stuck under subsidence
inversion right around 4 to 5 k ft through Mon night. Expect
clear, dry and unseasonably cool weather for Tues as 850 temps
plummet from near 9c Mon eve down to -7c. Temps Mon night will
drop to within a few degrees of 40 and will struggle to make it
to 50 on Tues with gusty westerly winds. By Tues night, winds
will drop out allowing for temps to diminish rapidly after
sunset under clear skies. Expect widespread temps below 30 Tues
night, except right along the coast.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Chilly and dry air mass on Wed into Wed night will moderate back
toward normal heading into Thurs as high pressure at the sfc
moves nearly overhead with bright early Dec sunshine and slight
ridging aloft. After a chilly start with below freezing most
places inland early Thurs, expect temps to rebound up near 60 by
Thurs aftn.

Next mid to upper low will rotate around, dropping toward the
Gulf coast on Fri. Associated sfc low will track eastward across
the south. Increasing southerly winds ahead of the system will
advect warm air into the Carolinas Thurs night into Fri with
increasing clouds and overnight temps in the 40s reaching up
into the mid 60s Fri aftn. Column will continue to moisten and
expect a decent soaking with this system Fri night into Sat.
Cold front should cross the coast on Sat with cooler and drier
air for the latter half of the weekend.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Areas of very patchy fog early this morning due to partial
clearing, abundant low-level moisture and light winds. However,
higher wind speeds generally keep the fog down, so if any fog
does hit the TAF sites over the next couple of hours, it would
likely only cause very brief IFR restrictions. Generally VFR
through this morning and afternoon. Strong low pressure system
approaches from the SW, with rain chances increasing from SW to
NE across the area this afternoon/evening ahead of the low.
Expect MVFR to IFR conditions in showers this evening through
the end of the period. Winds are from the NE now, but will veer
towards the SSW throughout the day. Gusts to 20-25 knots start
late Sunday night.

Extended Outlook...Additional MVFR/IFR conditions possible through
Monday due to low ceilings and visibility in rain. VFR returns
Tuesday and stays for the foreseeable future.

&&

.MARINE...
Through Monday: Worsening marine conditions through this period in
association with an intensifying low pressure system approaching the
area. Sub-SCA conditions through midday today as sfc high pressure
remains just off to the NE. The high then quickly retreats late in
the day as the aforementioned low slides into the central Gulf coast
states and the pressure gradient steadily tightens over the local
waters. Issued a ramp-up SCA starting mid/late aftn, with at least
12 hr of SCA conditions expected before a Gale Warning goes into
effect early Mon morning. The Gale Warning is for frequent gusts up
to 35 kt as a strong low-level jet moves over the waters and sfc low
pressure further strengthens. Seas up to 8-10 ft. There is also a
chance for waterspouts late tonight into early Mon. The Gale Warning
runs through 7pm Mon before winds start to diminish slightly.

Monday night through Thursday:
Cold front will move farther offshore Mon night with stiff
westerly offshore flow keeping seas highest in outer waters.
Overall expect Small Craft Advisory conditions continuing Mon
night into Tues with seas up to 5 to 8 ft. As winds diminish
through Tues aftn, expect seas to drop down to 3 to 5 ft in
lighter W-NW flow. Seas will be down less than 3 ft by Wed as
high pressure migrates overhead. The center of the high will
shift off the NC coast late Thurs with winds swinging around
becoming onshore and then southerly by Fri ahead of next system
moving across the Southeast.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory from 4 PM this afternoon to 4 AM EST
     Monday for AMZ250-252-254-256.
     Gale Warning from 4 AM to 7 PM EST Monday for AMZ250-252-254-
     256.

&&

$$
SYNOPSIS...ILM
UPDATE...III
NEAR TERM...MAS
SHORT TERM...RGZ
LONG TERM...RGZ
AVIATION...IGB
MARINE...MAS/RGZ

NWS ILM Office Area Forecast Discussion