Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 250532

Area Forecast Discussion
National Weather Service Wilmington NC
1232 AM EST Sun Feb 25 2018

Warm weather will continue until a cold front arrives on Monday.
Temperatures will only be cooled to normal Tuesday and
Wednesday. Another cold front is expected late Thursday.


As of 645 PM Saturday...Skies have cleared rapidly this evening
as the daytime cumulus clouds dissipated with the loss of
heating. The big question of the night is how much low stratus
and/or fog will develop late? Compared to last night it appears
we`re slightly drier with dewpoints 1-3 degrees lower across the
board. It also appears forecast wind speeds at the surface and
at the 975 mb level (appx. 1000 feet up) are higher than last
night. This argues for a lower fog risk, but could still allow
some low stratus to develop late tonight into early Sunday

I`ve made a couple of edits to the forecast to forecast nearly
clear skies through midnight and downplay fog chances to
"patchy." I`ve also removed the slight chance of showers along
the coast late as it appears the convergent plume of moisture
from the Gulf Stream that fed showers into Cape Fear last night
will be absent given the veered low-level wind directions
expected tonight. No significant changes have been made to
forecast low temperatures, still expected to range from 60-63
which is normal for highs this time of year! Discussion from
300 PM follows...

Chartreuse colors becoming more common across our landscape, as
prolonged spring-like warmth spreads across the region. This
exceptionally mild pattern, which has also been record breaking,
will continue through Sunday. Low- level thickness
amplification over the interior Sunday afternoon ahead of an
approaching cold front, in vigorous SW wind flow, will provide
an opportunity to establish new record highs. Record maximum
temperatures for Sunday 2/25 include, ILM 81 in 1930 forecast is
81, FLO 79 in 2017 forecast 84, and CRE 77 in 1949 forecast 76.

A formidable dry cap aloft will prevent deep convection through
this forecast period, but a few showers may scrape the coast
and graze the Cape Fear region overnight into early Sunday. An
encroachment of showers late Sunday afternoon could begin to wet
I-95, as the forthcoming surface trough, moves eastward out of
the Appalachian foothills, where more concentrated SHRA will

Radiational fog again has potential to become widespread inland
tonight, as skies become clear in dissolving diurnal cumulus.
Increasing low-level jet although not strong, could produce
patches of low-stratus but good surface visibility instead. A
low-end threat of sea fog intrusion will remain in place for the
coastal zones.


As of 300 PM Saturday...Cold front moves into the area Sun
night, pushed east by movement of stacked low across the western
Great Lakes. Elongated 5h ridge off the Southeast coast
promotes deep southwest flow, leading to increasing moisture
over the Southeast Sun night. Precipitable water reaches 1.7
inches in latest soundings which is right around the all time
max based on sounding climatology. Front ends up laying parallel
to the deep southwest flow as it settles into the area. The
front lingers on Mon before a shortwave, emerging from the
Desert Southwest Sun, helps drive the front south and east of
the area, opening the door for modified high pressure Mon night.

Best precip chances during the period will be Sun night and most of
Mon. Abundance of deep moisture in the area coupled with low level
convergence will lead to periods of showers with potential for
isolated thunder, especially Mon. There will also be a series of
weak shortwaves moving up the west side of the elongated ridge. No
single wave is particularly strong but these features will likely
help enhance any ongoing convection. Instability and shear are
limited and low level jetting is quite anemic. Thus severe weather
is not likely to be an issue. Rainfall will range from a quarter
inch to half an inch for most areas. Lows well above normal will
continue Sun night, but there will be a change on Mon. Warm start
coupled with clouds and showers results in highs in the mid to upper
60s. However, the passage of the front during the day will result in
temps starting to drop during the afternoon hours. High building in
Monday night will be accompanied by some modest cold advection and
lows will drop into the mid 40s by the end of the period.


As of 300 PM Saturday...Surface winds will be veering from NE to E
as Tuesday progresses due to high pressure sliding by to our north.
This veering continues Tuesday night into Wednesday paving the way
for advection of warm and moist air. Clouds will increase as will
rain chances though the latter may hold off until Wednesday night
into Thursday with the actual surface warm front. Tough call whether
or not we dry out in the warm sector, the main factor being how far
north the warm front lifts. If we do catch a break in the rain it`ll
be short-lived as the next mid level impulse and surface wave
approach from the west. This system pushes through Thursday night
into Friday morning and is starting to look rather wet. This system
deepens and quickly occludes off the Delmarva coast, readily pushing
some colder/seasonable air into the Carolinas.


As of 06Z...Expect mostly VFR conditions through the period. The
pressure gradient has increased sufficiently to impede any
serious fog development although a brief period of MVFR could be
reported later this morning. A cold front and some sea breeze
convergence will lead to some shower activity inland late Sunday
but any flight restrictions are expected to be fleeting.

Extended Outlook...VFR with periods of SHRA/MVFR Sun night into Mon.
VFR Tue. VFR with periods of SHRA/MVFR Wed/Thu.


As of 645 PM Saturday...Very few changes are needed to the
forecast this evening. We are still anticipating areas of sea
fog to develop overnight and persist into the first few hours of
Sunday, particularly over the cooler nearshore waters.
Discussion from 300 PM follows...

SE waves around 3 feet every 9 seconds moving through the 0-20
NM waters, with a light to moderate chop inshore to linger
through afternoon. It does not appear that an `Advisory` or
`Exercise Caution` headline will be needed this period, but
Sunday afternoon, SW gusts to 20 KT and seas of 4 feet offshore
will be common. The notable change is that dominant periods will
shorten to 5 seconds, making for a much bumpier boat ride by
Sunday afternoon. Inshore water temperatures remain chilly,
around 60 degrees.

As of 300 PM Saturday...Southwest flow at the start of the
period will gradually weaken Sun night into Mon. Bermuda High
will sink south and weaken as cold front slowly moves in from
the west-northwest. Weakening gradient will drop speeds from 15
to 20 kt late Sun to 10 to 15 kt by daybreak Mon. The front
moves over the waters later Mon with winds becoming light and
variable as the boundary briefly hangs up in the area. Northerly
push late Mon into Mon night drives the front south of the
waters and sets up a period of modest cold advection. High
building in helps pinch the gradient and the development of
northeast flow will result in a cold surge Mon night Speeds
increase to 15 to 20 kt as the period comes to an end. Gradually
decreasing wind speeds Sun night into Mon allows seas to fall
from 3 to 4 ft at the start of the period to 2 to 3 ft on Mon.
Once the northeast surge develops Mon night seas will build,
reaching 3 to 5 ft before the end of the period.

As of 300 PM Saturday...High pressure progressing eastward and
staying well to our north Tuesday to yield NE winds turning to E
and easing. Very light winds slated for Wednesday while the
veering in direction continues. Southerly flow remains
established on Thursday as low pressure approaches from the
west. WNA is quite aggressive in building seas up to advisory
levels and is seemingly too fast. As such shaved about a foot
off of guidance.




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