National Weather Service United States Department of Commerce

 


000
FXUS62 KILM 240643
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
241 AM EDT Tue Oct 24 2017

.SYNOPSIS...
A strong cold front will move east across the area brining drier and
eventually cooler air. In the wake of the front, dry and cool air is
expected through Thursday as Canadian high pressure takes hold. A
warming trend begins Friday. Shower chances increase Saturday as a
weak area of low pressure develops ahead of a second cold front.

&&

.NEAR TERM /THROUGH TUESDAY/...
As of 830 PM Monday...Axis of surface-based instability was
moving eastward across the Pee Dee region as of 00Z, with LI`s
of -2C to -3C extending from near LBT southward through
Kingstree. Modest surface pressure falls were occurring just
east of this axis of instability, and will transition eastward
and off the coast over the next few hours. Although backing of
the surface winds in response to these pressure falls has been
modest across the CWA, the shear profiles as evidenced by KLTX
VWP will remain conducive for storm rotation through the remainder
of the evening. Latest HRRR indicates the thunderstorm activity
will move off the coast around 06-07Z.

Cool advection lags considerably behind the wind-shift though
dewpoints may start dropping Tuesday afternoon temperatures will
still warm up into the upper 70s, a solid category above
climatology.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...Very quiet conditions will settle into
the area as a deep full latitude mid level trough moves from the
Tennessee Valley to just offshore through the period.
Precipitable waters dip to near one quarter of an inch by late
in the period. At the surface a somewhat blustery pressure
gradient will reside across the area and this is reflected n the
guidance. There may be some decoupling early Thursday morning
allowing temperatures to possibly drop to the coolest readings
of the season in some areas with lower to mid 40s area wide.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 PM Monday...Very cool temperatures start the extended as
Canadian high pressure settles across the area before pushing
offshore Friday. Temps Thursday will likely be about 5 degrees below
climo before recovering to more seasonable temps Friday as the
surface high shifts offshore. Moisture will begin to increase
Saturday on increasing southerly winds as a pre-frontal airmass
returns ahead of a deep mid-level trough pushing through the MS VLY.
This will drive a cold front across the area Saturday night into
Sunday. Ahead of this feature, a weak area of low pressure may
develop and move just off the coast, and while total column
moisture remains confined below 700mb, showers are possible late
Saturday through Sunday morning associated with this feature.
This front will bring the potential for the coldest air of the
season behind it, as 850mb progs drop below 0C and extended MOS
numbers feature values as much as 10 degrees below climo early
next week.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
As of 06Z...Winds will remain SW through today as a cold front
moves slowly east. Drier air will make its way in behind the
front with last of thunderstorms making their way off the Cape
Fear coast. Some lingering moisture in the way of strato cu
around 5 to 7 kt ft will remain, but residual low level moisture
will produce areas of fog through this morning. The fog will
lift with some stratus around through mid morning and then most
places should become mainly clear. Winds will remain out of the
SW until later today when winds shift to the W-NW. These impacts
will affect all terminals through the early morning period with
MVFR to IFR conditions in fog with low vsby and ceilings.

Extended Outlook... VFR Wednesday through Friday. Slight chance for
showers Saturday.

&&

.MARINE...
NEAR TERM /THROUGH TUESDAY/...
As of 830 PM Monday...Latest buoy obs are indicating strong
southerly winds across the waters, with gusts of 25-30 knots.
Seas at buoy 41013 were running near 8 feet. Latest guidance
suggests winds will diminish late tonight across the SC waters,
and early Tuesday morning north of Cape Fear. Seas will subside
below SCA thresholds beginning early Tuesday south of Little
River Inlet, and by early afternoon across the waters north of
Little River Inlet in the wake of the wind shift. Won`t make
changes to the SCA at this time, but if this timing expectation
holds, we may be able to remove the southern waters from the
SCA a little earlier on Tuesday than 18Z.

SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...Northwest winds of 10-15 knots and on
occasion 15-20 knots will prevail across the area through the
period. The persistence will be provided by a very deep and slow
mid level trough at 500mb that trudges across the conus from
the Mississippi Valley. Significant seas will be mostly 2-4 feet
with the higher values across the outer waters with the
offshore flow.

LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 300 PM Monday...High pressure moving overhead the waters
Thursday into Friday will create gusty north winds early
Thursday before weakening to less than 10 kts and shifting
slowly to NE Friday, and then E on Saturday. A secondary front
approaching very late Saturday may cause winds to uptick again
at the end of the period. The gusty north winds early will keep
seas elevated at 3-4 ft the first half of Thursday, before
falling back to 1-3 ft Fri and Sat. The increased winds late
Saturday may cause seas to begin to rise again at that time.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...Small Craft Advisory until 2 PM EDT Tuesday for AMZ250-252-254-
256.

&&

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