Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 170540
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1240 AM EST Tue Jan 17 2017

.SYNOPSIS...
A warming trend will occur Tuesday and Wednesday ahead of a
cold front which will drop south through the Carolinas late
Wednesday. Cooler and drier high pressure will follow on
Thursday. Low pressure moving up from the Gulf coast will
drag a warm front through the area on Friday. High pressure
will build in on Saturday before another system brings
unsettled weather for Sunday.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 1030 PM Monday...Latest HRRR continues to include patchy
light rain during portions of late this evening into the
overnight period...mainly along and west of the I-95 corridor.
Also, HRRR includes showers over the coastal counties mainly
from Horry County northward, and the adjacent coastal waters.
Once again upped the cloud cover to mostly cloudy or completely
overcast via latest satellite imagery trends and 18Z model
data. Continued with the patchy to areas of fog late this
evening and overnight given latest sfc obs trends and locally
run fog algorithm. The low stratus to affect the ILM CWA
Carolina Coasts and adjacent waters and refrained from
indicating sea fog at this juncture with the difference between
sfc dewpoints and SSTS not large enough. Temps tonight will
either hold steady or drift slightly lower from current values
thru this evening and overnight. Basically, not your normal
diurnal temp curve.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...For as weak as the aforementioned near
term warm advection is Tuesday will sure turn out a mild
afternoon. This will be more a function of not being trapped
under a deep and moist inversion. The moisture will not be
completely eroded however as forecast soundings show some
lingering moisture in the 3-5kft layer as well as above about
7500ft. The high level moisture in particular probably lingers
Tuesday night and then low level moistening gets underway
Wednesday compliments of approaching cold front. Timing
differences with respect to the front are affecting
temperature guidance with the slower WRF allowing for an even
warmer afternoon than the quicker GFS. Stayed closer to the
lower values due in part to support from the EC. Any
significant rainfall will stay north of the area underneath the
upper trough though a few sprinkles or stray hundredth of an
inch or three cannot be ruled out locally.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 PM Monday...Unsettled remains the operative word
for the extended period courtesy of a highly amplified and
shortwave laden pattern.

The first significant system for the eastern Carolinas arrives
late Thursday into early Friday via a shearing mid level system
moving across the Tennessee and Ohio valleys. A weak occluded
front is paired with this system as is a stationary front to the
south but these have little impact on the sensible weather.
Overall the inherited chance of showers still looks good.

The second more potent system at least to this point arrives late
Sunday into early Monday via a more powerful and closed shortwave
traversing a similar path to the first system. This system
continues to strengthen via the medium range guidance with good
moisture advection from the Gulf of Mexico and Atlantic.
Combined with good difluence aloft the elements for a soaker are
in place. Citing the dynamics, a high shear/low cape convective
event is possible with plenty of details to be determined in
the coming days.

The temperature forecast has shown little change with the latest
guidance and with a moisture laden period (even outside of pops
plenty of cloud cover) there shouldn`t be much diurnal variation.
Expect highs generally in the 60s and lows in the middle to upper
40s with some areas (generally coastal and southern) not dipping
below 50.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
As of 06Z...Expect mainly IFR or LIFR conditions overnight as
stratus increases and lowers. Light northeast winds will
prevail. After daybreak, expect low cigs and some visibility
restrictions to persist until inversion breaks near midday with
the passage of a warm front. Thereafter, cigs will lift to VFR
as winds become west-southwest around 5 to 10 kt.

Extended Outlook...A cold front Wednesday afternoon may be
accompanied by showers. Showers Friday may bring a period of
MVFR. Otherwise expect VFR.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1030 PM Monday...A stalled boundary extending inland in
the vicinity of South Santee River has hooked up with an
inverted sfc trof of low pressure just offshore and parallel to
the Carolina Coasts. The 2 boundaries as a whole will begin
lifting northward overnight into daytime Tuesday. This sfc
pressure pattern and rather relaxed sfc pg will for the most
part produce NE winds at 10 to 15 kt, veering to the ENE to ESE
around 10 kt by daybreak.

Significant seas will run 2 to 3 ft. A degrading ESE 1 to 2
foot ground swell at 9 second periods will combine with locally
produce wind driven waves at 5 to 6 second periods.

SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...With the warm front lifted out to our
north on Tuesday the gradient will remain quite weak. SW flow
will be capped at just 10kt and seas may drop to just 2 ft. The
approach of a cold front will veer and increase the flow
gradually Tuesday night and then moreso Wednesday. This front
may pass through either midday or late afternoon Wednesday. The
cooler surge behind this boundary is tempered enough that no
headlines likely follow its passage.

LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 300 PM Monday...Expect essentially light and variable
winds Thursday via a weak pressure pattern. Wind fields will
show a little better definition late Thursday into Friday as a
southwest flow develops ahead of a weak front. Speeds increase
briefly to 10-15 knots. By Saturday a weak northerly flow
develops. Significant seas will be 2-4 feet as the weak wind
fields and fetch change keep them somewhat in check.

&&

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

&&

$$

NEAR TERM...DCH
SHORT TERM...MBB
LONG TERM...SHK
AVIATION...SGL/RJD


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