Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 152014
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
314 PM EST Sat Feb 15 2020

.SYNOPSIS...
A weak wave of low pressure developing off the coast will
spread scattered showers across the eastern Carolinas Sunday.
This system should move offshore Monday. Showers will again
develop Tuesday in advance of a cold front, expected to move
across on Wednesday. Canadian high pressure will build into the
Carolinas late this week bringing colder temperatures and dry
weather.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
Shallow anticyclone to drop SE over the OBX and Cape Fear
region tonight. WSW winds aloft will tilt the low-topped high
seaward, and return flow will begin off the surface while the
high is sheared from the top down, becoming erased from most
synoptic maps after morning Sunday.

Marine moisture just offshore will provide needed substance for
stratocumulus clouds along the coast, as the flow in the moist layer
turns landward. As a result, after an evening of plummeting
temperature curves, temperatures will level off after 1am in most
areas, rising a few degrees into pre-dawn near the coast due to
cloud encroachment, and southerly boundary layer wind.

Short-wave energy from the WSW will help energize a coastal trough
Sunday, developing a weak but pivotal surface low tracking along it
Sunday afternoon through early on Monday. This in essence provides a
decent chance of showers for the eastern 1/2 of our NE SC and SE NC
land zones in this period. The bulk of precipitation to be off the SE
NC coast after 8am, with rain amounts up to 1/4 inch by the coast,
and .05-.15 inland, lowest far western zones.

Max-T near 60 by the coast Sunday, cooler middle 50s inland. Tonight
chilly as clear evening skies and light wind prevail, but min-T
around 10 degrees milder Monday morning compared to Sunday morning,
joined by occasional showers Sunday night to daybreak Monday.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Sunday night`s weak wave of low pressure should be located east
of the Gulf Stream by daybreak Monday. Shallow northeast flow
behind the low will keep some stratus clouds and maybe a
sprinkle in the area during the morning, but the GFS and ECMWF
show clouds scouring out during the day. The 12z NAM, and to an
extent the 12z Canadian maintain the low clouds through the
afternoon. Assuming we do see afternoon sun, highs should reach
the low-mid 60s away from the ocean. If the NAM and Canadian
are correct, temps could remain in the 50s all day.

Low-level winds will begin to veer Monday night into Tuesday in
advance of a cold front moving across the Mississippi River.
Moisture should deepen throughout the day Tuesday, aided by a
series of disturbances arriving in the subtropical jet. This
should yield showers, especially during the afternoon. Scattered
showers should continue through Tuesday night as the front dips
into the central Carolinas late.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
There is still roughly six hours of timing differences among
the various models about when the cold front actually pushes
south across the eastern Carolinas Wednesday. This could make a
large difference in high temperatures. I`m banking on a
slower/later frontal timing which should allow morning
temperatures to remain in the 60s prior the frontal passage.
Increasing northerly winds should overspread the area during the
day, with showers thinning out from north to south as cool, dry
air deepens behind the front.

The front should make it into north Florida before stalling
Thursday morning. A very positively tilted upper trough in the
polar jet will slide east-southeastward, moving across the
Carolinas Thursday night. A diffluent upper air pattern and
150+ knot jet streak moving off the Mid-Atlantic coast should
induce surface low pressure to form along the front off the
Georgia coast during the day Thursday. Backing mid-level flow as
this low develops should spread one more batch of rain across
South Carolina and perhaps southern North Carolina. At this time
it appears the cold air will chase the thinning moisture off
the coast Thursday night, precluding any chance of snow here. If
the upper trough slows down, there`s a chance flurries could
develop on the northern edge of the precip shield. This is the
same system that many folks shared several days ago on social
media when one or two models showed a significant Carolina
snowstorm at day 9.

What is more certain is that dry and colder air should plunge
across the area behind the departing upper trough Thursday night
through Saturday. This could yield freezing temperatures
Thursday night, or more likely Friday night as winds become
light with the next high building across the area. Agricultural
interests may need to monitor this given the advanced state of
some plant growth.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
High pressure will remain in control through the forecast
period. Time height shows very dry air aloft, with little to no
clouds expected through the overnight hours. Northeast winds will be
moderate today, becoming light this evening as an inversion sets up.
Sunday, increasing clouds ahead of the next system. Light and
variable winds.

Extended Outlook...Unsettled weather Sunday night through Thursday
with possible MVFR/IFR conditions.

&&

.MARINE...
Marine conditions to improve enormously, as winds become weak over
the waters. Part of the cold high that has caused the wind will
break apart and weaken over the waters tonight. A weak coastal
trough offshore will result in occasional showers Sunday afternoon
through early Monday morning, however winds will remain 12 kt or
less during this time. The trough may push near shore late Sunday,
bringing a period of SE winds around 10 kt, while the showers reduce
visibility at times to 3-4 NM over the waters Sunday night. No TSTMs
expected at this time. The wave spectrum a docile one, light chop
and wind-sea, co-joined by SE waves 1-1.5 feet every 9 seconds. A
cold front will approach from the north daybreak Monday.

Weak low pressure off the coast Monday should provide a light
northeast wind for the Carolina coastal waters. Rain chances
appear quite small as most of the deeper moisture and lift will
have pushed away from the coast before daybreak. High pressure
building down from the north will be a transitory feature,
retreating out to the east Monday night. Winds should veer
southerly Tuesday in advance of a cold front approaching from
the west. This front should develop a large area of showers
ahead of it, finally reaching the area sometime Wednesday.

Models still have a roughly six hour spread in timing as to
when the actual wind shift arrives, but it appears that by
Wednesday afternoon increasing northerly winds should be
spreading down across the coastal waters, increasing to a solid
20 knots Wednesday night. Even stronger north winds are
expected on Thursday as low pressure develops along the front
off the Georgia coast. Winds could exceed 30 knots on Thursday,
and the potential for gale-force winds, especially in gusts, is
growing.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.

&&

$$

SYNOPSIS...TRA
NEAR TERM...MJC
SHORT TERM...TRA
LONG TERM...TRA
AVIATION...43
MARINE...MJC/TRA



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