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717
FXUS62 KILM 180726
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
326 AM EDT Wed Apr 18 2018

.SYNOPSIS...
High pressure will move from the Gulf of Mexico to Atlantic
through today, and warm southwesterly flow will develop across
the area. A dry cold front will move across the area Thursday
night, followed by high pressure Friday and Saturday. A low
pressure system will move across the Gulf Coast states and bring
increasing chances of rain late Sunday into early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 300 AM Wednesday...A cold front resides just to the north
this morning and will make little progress to the south as a
strong west to southwest flow develops or actually intensifies
later today. In fact the warm flow is already keeping overnight
temperatures elevated across most of the area and in some cases
readings have increased. With little in the way of cloud cover
expected it will be a warm and blustery day as deep mixing will
allow winds of 20-30 MPH with higher gusts to develop. With such
a warm start, this usually portends to max temperatures
exceeding the warmest guidance and the forecast has been
adjusted to reflect this. Expect lower 80s along the coast with
middle 80s inland. Only the beaches should remain coolish as the
sea breeze should have difficulty penetrating inland. Tonight
will remain blustery and on the warm side as well under mostly
clear skies.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 300 AM Wednesday...A very warm Thursday will give way to much
cooler temperatures Friday, but lots of sunshine is expected through
the end of the week.

Period begins with residual mid-level ridging and a warm sector
regime across the eastern Carolinas. Although this airmass is
narrow, temps are forecst to climb quickly Thursday to around 80
most of the area. The exception will be along the coast thanks to a
sea breeze and onshore southerly flow, and far NW zones which will
experience slightly earlier cloud increase with the cold front. This
front will be driven down across the CWA late on Thursday in
response to a vorticity impulse rotating through the amplifying
eastern trough. Some guidance does paint some light QPF Thursday
evening, but forecast soundings appear too dry for any rainfall and
will instead show increasing clouds, especially NC zones, but keep
POP silent. CAA is strong behind this front, and 850mb temps plummet
from near +14C to around +2C by Friday morning, so after an above
normal day, mins by Friday morning will likely fall to below climo,
low to mid 40s, with gusty winds. In fact, winds both ahead of, and
behind, this front will be strong, gusts up to 30 mph are likely
from the SW Thursday aftn, remaining up to 20 mph from the NW
Thursday night.

On Friday, surface high across the Great Lakes expands SE, and
although temp advection will become neutral and sunshine abundant,
highs are forecast to climb only into the mid 60s. The airmass
advecting into the region Friday is very dry, PWATs are forecast to
drop to around 0.2 inches which would be near or below the all-time
lowest for the date according to SPC sounding climatology for MHX.
This suggests that as winds ease Friday night, good radiational
cooling will occur, and lows could drop into the upper 30s in some
spots, low 40s elsewhere.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 300 PM Tuesday...Broad surface high pressure over the
Great Lakes will extend across the area, resulting in cool and
dry northerly flow, which will veer to the northeast by
Saturday. A closed mid-level low and associated surface system
will slowly drift across the Gulf Coast states Sunday through
Tuesday, and bring increasing chances of rain late in the
weekend and into early next week. The GFS and ECMWF keep the
bulk of the moisture and upper-level diffluence just south of
the forecast area, however confidence is somewhat low in how
this will ultimately evolve, as there is some suggestion in the
models that it may become cutoff and slow or stall over southern
Georgia or the Florida Panhandle by Tuesday.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
As of 06Z...VFR conditions expected through the period. The main
issue will be strong winds, which will take off just past
daybreak with deep mixing. Most sites will see southwest winds
of 15-20 knots sustained with gusts exceeding 25 knots moreso
inland. I also maintained the low level wind shear at all sites
through the remainder of the overnight hours.

Extended outlook...VFR.

&&

.MARINE...
NEAR TERM /THROUGH WEDNESDAY/...
As of 300 AM Wednesday...Winds and seas teasing small craft
criteria this morning mostly across the outermost waters. The
trend should remain steady for the next few hours before
elements ramp up later this morning as a strong southwest flow
intensifies. Will maintain the start time to the advisory at 1
PM this afternoon. The southwest flow of 15-20 knots will
develop and actually increase a bit this evening before ticking
down slightly by early Thursday morning. Significant seas will
just eclipse the six foot threshold for the advisory but
guidance doesn`t show seas advancing much beyond that point.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 300 AM Wednesday...Small Craft Advisory conditions will be
ongoing to start the period Thursday as a cold front approaches from
the NW. This leaves SW winds of 20-25 kts across the waters the
first half of Thursday, followed by a rapid wind shift to the N/NW
post-FROPA Thursday night. A brief reprieve in wind speeds is likely
during the actual frontal passage, but otherwise speeds will remain
20-25 kts regardless of direction, and other than a small window of
sub-SCA conditions, a renewed SCA will be likely Thursday night.
Winds will ease rapidly during Friday as high pressure builds in
from the NW behind the cold front, allowing speeds to drop to around
10 kts late Friday and Friday night, with direction veering slowly
to the NE. Highest seas are expected Thursday when 4-6 ft will be
common, and even with the continued elevated wind speeds post cold
front, the offshore direction and more limited fetch will keep wave
heights to 3-5 ft into Friday morning. Seas then become more
uniformly around 2 ft as the winds ease through the remainder of the
period.

LONG TERM /SATURDAY THROUGH SUNDAY/...
As of 300 PM Tuesday...Surface high pressure will build across
the Great Lakes Friday and Saturday, and produce northeast flow
across the waters both days. The high will weaken and extend
across the DelMarVa peninsula Saturday night into Sunday, and as
a result winds will veer towards the east during that time.
Winds Friday morning will start off 15-20 kt, but diminish by
midday as the gradient weakens, and the direction may become
somewhat variable at times. It will begin to tighten up again
Sunday afternoon as low pressure slides across the Gulf Coast
states.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory from 1 PM this afternoon to 6 PM EDT
     Thursday for AMZ250-252-254-256.

&&

$$
SYNOPSIS...JDW
NEAR TERM...SHK
SHORT TERM...JDW
LONG TERM...CRM
AVIATION...SHK
MARINE...