Area Forecast Discussion
Issued by NWS Wilmington, NC

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FXUS62 KILM 211900

Area Forecast Discussion
National Weather Service Wilmington NC
300 PM EDT Wed Mar 21 2018

Low pressure will pull away from the East Coast tonight as
Canadian high pressure builds in from the west. Well-below
normal temperatures will continue for the next several days,
with frost or even freezing temperatures possible at night. Low
pressure will move across the Carolinas Saturday night and
early Sunday bringing rain, followed by below normal
temperatures and dry weather again early next week.


As of 300 PM WEDNESDAY...Broad cyclonic flow continues across the
region this afternoon from deep low pressure moving up the east
coast. Some residual light rain and drizzle remains but the
trend is for decreasing coverage. By 0000 UTC only the extreme
northeast zones should be seeing any activity. Skies should
clear out later tonight from south to north. For overnight lows,
guidance is fairly consistent with the NAM/MET numbers once
again cooler. We continue to lean toward the slightly warmer MAV
numbers which show mostly middle 30s. An expected mixed
boundary layer should keep readings in check as well. For
Thursday mostly sunny and cold with highs in the middle to upper


As of 300 PM WEDNESDAY...`Dry and Cold` captures the essence of
this period, as PWAT values take a dip to around a quarter of
an inch Thursday night and early Friday, with near freezing
conditions likely for pockets of SE NC before daybreak Friday,
and again for interior SE NC early on Saturday, as the growing
season is underway.

The limited geographical extent of forecast Min-Ts below 32
either morning, is not expansive enough to raise a `Freeze
Watch`, and confidence level of a widespread freeze across any
particular county right now, is low. The deep and arid NW flow
will impart 10-15 mph surface winds Friday, and plentiful
sunshine minutes will rack up Friday. Clear/chilly into Friday
evening, possibly 10-12 kft clouds early Saturday impinging
inland zones from the west to east.


As of 300 PM WEDNESDAY...A warm front lying across South
Carolina on Saturday should lift northward during the day as
surface low pressure moves eastward across Tennessee. This low
is being supported aloft by a shortwave rotating southeastward
around the longwave trough off the East Coast. Model differences
with this shortwave are generally minor, however the ECMWF is
stronger and a little slower with the shortwave than the GFS.
Although both models show rain developing Saturday night into
Sunday, this probably explains the better developed low-level
thermal/moisture advection fields shown on the ECMWF. PoPs have
been increased to 50-60 percent for this period, and it`s
looking more and more likely we`ll see a widespread 0.20 to 0.30
inch rainfall event. The ECMWF shows a stable airmass through
the event, while the GFS shows only a tiny region of elevated
instability Saturday night, too meager for a significant thunder

The surface low should jump the Carolinas Saturday night,
redeveloping just off the coast where low-level baroclinicity is
significantly greater than inland. Cold northerly winds should
punch southward behind the developing low. Sunday`s high
temperature forecast is actually quite difficult since it`s
tough to know exactly where the front will be located at 7 AM,
and temperatures could actually fall throughout the day in the
strong low-level cold advection. A model blend gives mid to
upper 50s across SE North Carolina and upper 50s to around 60 in
South Carolina, however that could easily be 10 degrees lower
if faster cold frontal movement (like shown on the GFS) occurs.
Light rain should taper off during the afternoon with skies
partially clearing Sunday night as moisture thins from north to

Dry and unseasonably chilly weather is expected Monday and
Tuesday as Canadian high pressure builds down the East Coast.
Our 850 mb temps should hover in the +1C to +3C range both days,
between the 10th and 20th percentile for late March. Of
agricultural concern is a possible frost or even freeze event
coming up Monday night as surface winds drop off with the
incoming high. On Wednesday the surface high should finally move
off the East Coast. A westerly component to the low-level flow
will finally bring warm advection and temperatures should pop
back to seasonal norms.


As of 18Z...This afternoon VFR at the southern terminals. VFR
developing at KLBT and KILM within the next 1-2 hours. Winds will be
westerly gusting to 20-25 kt. Gusts subside 23-00Z and skies will
become scattered by midnight Z. Thursday VFR/scattered skies with
gusty northwest winds to around 20 kt by mid-morning.

Extended outlook...VFR. MVFR/IFR/Rain Saturday night and Sunday.


As of 300 PM WEDNESDAY...Winds and seas remain elevated this
afternoon as cold air advection under a deep east coast cyclonic
flow continues. Sustained winds are a good 20-25 knots and in
some cases higher and will only see a very gradual decline
through the overnight hours to the lower end of the range. By
Thursday evening winds will be down to a 15-20 knot range.
Significant seas will be 5-8 feet overnight and fall to 2-4 feet
by tomorrow evening. The small craft advisory for all waters
goes through 6 PM Thursday but the latest high resolution wave
guidance shows seas falling a little faster and subsequent
shifts may be able to end the advisory a little quicker.

As of 300 PM WEDNESDAY...NW gusts to 25 KT offshore may be ongoing
Thursday evening, but the overall prospects, will trend to
easing wind and subsiding seas, but only a bit, yet enough to
put away advisory flags heading into Friday. NW winds 10-15 kt
Friday and Friday night, will occasionally gusts to 20 kt. No
obstructions to visibility this period, and no TSTMS or
precipitation. Seas will be mainly comprised of NW wind-seas,
implying fairly nice marine conditions inshore, noticeably
bumpier outer waters.

As of 300 PM WEDNESDAY...A warm front will lift north across
the area Saturday afternoon as low pressure moves eastward
across Tennessee. As often occurs, the low should jump the
mountains and redevelop just off our coast, dragging the front
southward again as a cold front Sunday morning. Mariners should
expect a sudden increase in north-northeasterly winds as the
front dives through, with Small Craft Advisory conditions
developing and likely persisting through Monday as strong
Canadian high pressure builds southward. Our forecast shows
20-25 kt winds Sunday afternoon through Monday, but it`s
possible there will be some 30+ knot gusts thrown in there
during the period of most rapid thermal advection Sunday
afternoon or evening.


MARINE...Small Craft Advisory until 6 PM EDT Thursday for AMZ250-252-



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