Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 042019
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
319 PM EST Sun Dec 4 2016

.SYNOPSIS...
Low pressure moving up the coast will bring light rain
tonight. After a break on Monday a stronger system will affect
the region Monday night into Tuesday leading to a more
substantial rainfall. Quiet and seasonable mid week weather will
be followed by Arctic air arriving Thursday night.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 300 PM Sunday...Dense mid and high clouds have been traversing
the Carolinas for 24 hours now courtesy of a powerful subtropical
jet being steered by upper level low pressure over northern Mexico.
Patchy light rain has been falling on and off all day from these
clouds with trace to .03" totals in most locations so far. This
should change rather dramatically tonight as a warm front developing
along the Georgia coast swings northward to near the Carolina coast
after midnight. Deep isentropic lift developing west of this
boundary should lead to widespread rain breaking out this evening
and persisting much of the night. Rainfall amounts don`t look quite
as large as we were thinking 24 hours ago, but 0.35" to 0.60" totals
are certainly plausible.

Temperatures have been stuck in the 40s and lower 50s all day. While
inland temperatures should hardly budge overnight, along the
immediate coast look for temperatures to rise by 5-10 degrees
overnight with the approach of the warm front. Low pressure
developing almost overhead after midnight should drag the front back
offshore before daybreak Monday.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Surface low pressure zipping away from the NC
coast Monday morning will have pushed the front a good 150-200 miles
south of the area by Monday afternoon. With the loss of isentropic
lift there should actually be some breaks in the clouds Monday with
rain chances dipping to only 10-20 percent by afternoon. Any
lingering morning rain along the coast should wrap up really quickly
with additional rainfall amounts less than a tenth of an inch after
7 AM. Highs Monday could approach 60 degrees, which is actually
below normal but will feel wonderful after the dreary and cold
Sunday we experienced.

The big upper low over northern Mexico will finally eject out to the
east Monday, leading to surface low pressure developing across the
Deep South Monday night. Strengthening southerly flow ahead of this
low should lift the stalled front northward again and bring it near
the Carolina coast by daybreak Tuesday. Isentropic lift west of the
front should again lead to widespread rain developing. With strong
wind fields and advection of warm air northward, elevated
instability should increase sufficiently that isolated thunderstorms
will remain in the forecast for late Monday night into Tuesday.

After the upper trough passes us by to the north Tuesday afternoon,
precipitation should largely end with the front slowly sagging back
offshore Tuesday night.

Two interesting features in this forecast I wanted to mention: one
is that the synoptic situation is actually favorable for a possible
gravity wave event Tuesday. (a very stable surface airmass west of
the front with unstable conditions aloft)  Should a gravity wave
develop across Georgia or South Carolina it would move eastward,
persisting until it reaches the surface front at which point it
should dissipate. Typically these waves produce wind gusts of 25-35
mph as they trickle along the back edge of a precipitation shield.
Also, with nothing to scour out the low level moisture Tuesday and
such low sun angles this time of year, stratus Monday night could
lower into a widespread area of fog Tuesday which might persist much
of the day west of the front. This could include the Pee Dee area
plus Lumberton, Whiteville and Elizabethtown.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 3 PM Sunday...Fairly seasonable temperatures expected
Wednesday and Thursday as a weak low level thermal ridge develops
ahead of the impending Arctic front.  Mid level flow will be out of
the WSW and not favorable for deep moisture through the column. The
boundary itself will thus likely move through rain-free but the
change in airmass will be starkly noticeable by Friday as highs
struggle their way into the mid 40s. Not much recovery is expected
Saturday after a downright cold night Friday night featuring lows in
the mid 20s. Saturday arguable may not feel as cold however as the
wind stays light due to the high building overhead. As the high
continues eastward Saturday night into Sunday some slow moderation
will get underway.

&&

.AVIATION /20Z SUNDAY THROUGH FRIDAY/...
As of 18Z...Confidence aviation conditions will deteriorate
through the period as a storm system impinges upon the eastern
Carolinas. At present we have VFR conditions with some patchy
light rain being reported from ceilings up around 9 kft.
Ceilings will lower all sites through the remainder of this
afternoon and into the evening hours, lowering below 1 kft from
west to east between sunset and midnight. Visibilities will
lower in rain and fog, decreasing to around 2 miles during
periods of heavier rain overnight. Low confidence in cigs rising
above IFR criteria near the end of the TAF valid period for our
inland sites. Coastal sites will likely remain socked in
through then.

Extended Outlook...Periods of IFR likely through Tuesday night due
to rainfall and low cigs/reduced visibilities. MVFR/VFR developing
on Wednesday and extending into Thursday.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 PM Sunday...High pressure along the Mid-Atlantic coast
will weaken and move offshore tonight. A warm front developing along
the Georgia coast will move northward tonight, ultimately reaching
the beaches late tonight. Northeast winds should turn southerly
after midnight. Low pressure developing overhead will push the
boundary back offshore with northwesterly winds developing by
daybreak Monday. Unfortunately for mariners, the approach of this
system will lead to increasing winds and seas overnight, and it
appears we should experience a period of 15-25 kt winds and 3-6 foot
seas late tonight into Monday morning.

SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...Low pressure moving out to sea late tonight
will push the front 150-200 miles south of the area for Monday.
North to northeast winds are expected much of Monday and Monday
evening as a result. However the approach of low pressure from the
Deep South will begin to tug this front northward again late Monday
night, and the boundary is expected to sweep back across the waters
as a warm front around daybreak Tuesday. This should allow wind
directions to veer southerly again with another increase wind wind
speeds to 15-25 kt.

LONG TERM /WEDNESDAY THROUGH FRIDAY/...

As OF 3 PM Sunday...Wednesday will offer up a weak pressure gradient
and thus fairly tame winds. Seas will still be slightly agitated
from the short term storm system, though well below any advisory or
headline levels. Winds ramp up Thursday as the Arctic front
approaches. This boundary looks to arrive a bit sooner than
previously thought and may blast across the waters during the
afternoon or evening. Small craft advisory may be needed
Thursday night and/or Friday.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory from 1 AM to 10 AM EST Monday for AMZ250-
     252-254-256.

&&

$$
SYNOPSIS...MBB
NEAR TERM...TRA
SHORT TERM...TRA
LONG TERM...MBB
AVIATION...REK


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