Area Forecast Discussion
Issued by NWS Wilmington, NC

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000
FXUS62 KILM 170813
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
313 AM EST Sun Feb 17 2019

.SYNOPSIS...
Cool and cloudy conditions will prevail today, with patchy
drizzle at times. Another cold front will bring a chance of rain
tonight and Monday. A stalled front and increasing Gulf
moisture will maintain unsettled conditions through the end of
week.

&&

.NEAR TERM /THROUGH MONDAY/...
As of 3 AM Sunday...Yesterday`s cold front is stalling along
the Georgia coast just south of Savannah. High pressure moving
off the Northeast coast later today and low pressure moving into
central Appalachians tonight will both act to lift the boundary
northward again, likely moving across our portion of the
Carolinas during the late evening hours. Although northeasterly
surface winds should continue up until the time the front
arrives, veering flow aloft and moisture advection from the
south should lead to cloudy skies continuing today and tonight.
The magnitude of isentropic lift is modest, however all models
show some light rain breaking out later today. The best
potential for measurable rain should be near and west of I-95
where moisture will be deepest courtesy of a plume of 700 mb
moisture originating from the western Gulf of Mexico.

As is typical in situations where a warm front is approaching, there
is a large range in model high temperatures for today. The 00z NAM
is my model of choice for this event, and keeps temperatures in the
40s all day across the Pee Dee Region to Lumberton and
Elizabethtown, with some lower 50s showing up across the Cape Fear
and Grand Strand areas.

As mild southerly flow mixes down to the ground behind the warm
front after midnight, look for temperatures to spike into the 60s
for most areas east of I-95. There`s considerable uncertainty with
regard to how far west of the interstate the front will get before
stalling and returning east again tomorrow. It`s possible
Hartsville, Bennettsville, and Maxton stay on the cold side of the
boundary through the event with temperatures never exceeding 50
degrees until Monday afternoon when the sun returns. Needless to
say, temperatures are the most challenging part of this forecast
with atypical temperature curves today, tonight, and Monday.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 3 AM Sunday...Period begins with front south of the area and
expansive high building in from the Upper Midwest. Progressive flow
aloft shifts the high over the Great Lakes Tue and the Northeast Tue
night. This allows weak coastal trough to develop over the nearshore
waters Tue into Tue night. Initially isentropic lift will be weak
and moisture below 7k ft is limited. On Tue the influence of the
high starts to weaken as low pressure starts to organize along the
boundary in the Lower MS Valley. Clouds will thicken and lower on
Tue with isentropic lift increasing late in the day. Light rain will
slowly spread over the forecast area from southwest to northeast
late Tue and Tue night. Forcing is not particularly strong and low
level dry air will be reluctant to modify. Best rainfall chances
will be late Tue night for most of the area. Cold advection and
cloud cover will keep highs below climo on Tue but cloud cover and
mixing will keep lows a little above climo both nights.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
As of 3 AM Sunday...Unsettled conditions will be the theme of the
long term with the forecast area in a wavering frontal zone through
Saturday. Mid-level ridging over the Bahamas and Southwest troughing
will prevent any features really capable of removing the frontal
zone while allowing a series of developing low passage through the
TN and OH Valleys.

-Although precip chances will be elevated for much of the
 period, total rainfall for the week will be limited.

-Most areas will see a quarter to half an inch of rainfall
 during the period. It is very unlikely that any day will be a
 washout.

-Although the front will be south of the area at times cold air
 will be lacking and high temperatures will be near to slightly
 above climo.

-Cloud cover and moisture will keep lows above to well above
 climo.

&&

.AVIATION /08Z SUNDAY THROUGH THURSDAY/...
As of 06Z....Low stratus behind a cold front stalling in the
Savannah vicinity will continue through the day. Low MVFR
conditions will prevail (1000-2000 feet AGL ceilings) with only
some tempo IFR (800 ft) ceiling possible before sunrise along
the coast. The front will return north tonight with ceilings
likely lowering to only 300-500 feet AGL by 00Z. Surface winds
will veer southerly between 02-05Z with winds aloft accelerating
substantially as a low-level jet organizes overhead, possibly leading
to low-level wind shear conditions.

Extended Outlook...In general, unsettled weather through
Wednesday with IFR/LIFR conditions possible at times.

&&

.MARINE...
As of 3 AM Sunday...A complex weather pattern will continue for
the next 36 hours as yesterday`s cold front returns northward
tonight as a warm front, then will move back offshore Monday
morning. These shifts in frontal position will be the result of
low pressure moving from Tennessee through the central
Appalachians and into the Northeast on Monday.

Northeasterly winds today will turn southerly tonight after the
front moves through, increasing to 15-20 kt after midnight. Seas are
anticipated to build to 4-5 feet, potentially approaching 6 feet
along Frying Pan Shoals late tonight into Monday morning. Winds
should again turn northerly Monday afternoon behind the front. Among
the various models, the 00z run of the NAM is our preferred model
for this forecast.

Weak coastal trough starts to take shape Tue, becoming more defined
Tue night. Trough develops as surface high, over the Upper Midwest
Mon night, quickly shifts east Tue and Tue night. Cold front that
building high pushes south of the waters will return north Wed into
Thu, shifting northeast winds to southwest for the middle of the
week. Front will linger just north of the area through Thu. Gradient
will be pinched at times, with wind speeds close to 20 kt. Seas
build to 3 to 5 ft late Mon night or early Tue in response to
northeast flow increasing to near 20 kt and seas in excess of 6 ft
will be possible Tue night into Wed. The development of southwest
winds later Wed will create chaotic seas, but decreasing speeds
should allow seas to fall during the mid to late week period.

&&

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

&&

$$

NEAR TERM...TRA
SHORT TERM...III
LONG TERM...III
AVIATION...TRA


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