Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 050001

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

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.


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.


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.


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.


As OF 00z...High confidence MVFR flight conditions will
deteriorate to IFR this evening at KFLO/KLBT. Although TEMPO
IFR could occur at the coastal terminals mainly due to vsbys if
heavier rain occurs before midnight, IFR in general at the
coastal terminals should hold off until just after midnight. IFR
will persist through 14-16Z at KFLO/KLBT, 15-17Z at the coastal
terminals with improvement to MVFR then VFR by 18Z all

Extended Outlook...IFR/rain likely Mon night through Tuesday night.
MVFR becoming VFR Wednesday and extending into Thursday. Slight
chance MVFR/showers Thurs night into early Fri.


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.

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.


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.


MARINE...Small Craft Advisory from 1 AM to 10 AM EST Monday for AMZ250-


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