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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KILM 221641
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
1241 PM EDT Tue Aug 22 2017

.SYNOPSIS...
Warm and humid weather will prevail through mid week. An
approaching cold front will bring increasing storms over the
area late Wednesday into Thursday. Canadian high pressure will
bring an early fall feel Friday and into the weekend. Breezy
conditions may develop late Sunday into Monday, as a tropical
low passes offshore and interacts with the Canadian high.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 10 AM Tuesday...Towering cumulus this morning are feeding
on a stream of tropical moisture, which is depicted well in
GOES-16 total precipitable water animations, winding from the
western Gulf of Mexico across the southern states to the coastal
Carolinas. An upper ridge was maintaining dry air above 20 Kft.
Weak surface boundaries will be sufficient to activate land
convection through morning near the coast with abundant moisture
below 400 mb, but the developing sea breeze front will gradually
become the primary focus, supporting the majority of showers
and TSTMS on a trend slowly farther inland through middle and
late afternoon. A broad warm ridge aloft will prevent most
storms from becoming severe, but dry air entrainment could
enhance the downdraft potential. The light steering winds and
overall low shear will keep impacts if any localized. August
heating plays a significant role today and after 6-7 pm, we
should witness a weakening coverage and intensity trend in
convection, becoming fair and balmy.

As of 300 AM Tuesday...Light showers were hugging portions of the
coast. Western Atlantic Ridge will get knocked down slightly as
a series of mid-level disturbances move up along the coast. The
Piedmont Trough and seabreeze will again be present. Expect
most of the convection to light up along the coast today in
association with the upper level shortwaves. As the seabreeze
moves inland during the afternoon, expect the convection to
shift more inland as well. Can`t rule out a shower or
thunderstorm in the I-95 corridor today, in closest proximity to
the Piedmont Trough, but again expect most of the convection
will be east of this major thoroughfare. Convection should wane
with stabilization of the environment this eve as a significant
shortwave trough moves downstream. However, models are showing
another approaching toward Wed morning. Thus will show POPs
waning in the early eve with some redevelopment after midnight.
Mixed signals as too how far inland convection will redevelop.
Favored the coast and offshore as this is the climatologically
favored area for nocturnal convection during the late summer.
Will keep an open mind for inland development given approaching
trough.

Opted for patchy to areas of fog with significant visibility
restrictions most likely inland through sunrise this morning. Highs
today will be in the lower 90s with upper 80s nearer to the coast.
This will put the heat index at or just over 100 degrees. Lows
tonight will be mainly in the mid and upper 70s.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 300 AM Tuesday...A cold front will approach from the northwest
Wednesday and move slowly through the area Wednesday night and
Thursday before moving off the coast Thursday night.  The result
will be an unsettled period with scattered showers and thunderstorms
through the period.  Max temperatures in the upper 80s to low 90s
Wednesday will moderate to the mid to upper 80s Thursday. Lows in
the mid to upper 70s Wednesday night will moderate to a range
from the upper 60s NW to mid 70s SE Thursday night.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 AM Tuesday...A strong Canadian anticyclone will continue
to press SSE into the area through the weekend, offering a dose of a
very early fall feel here with slight cooling and drying. As the
strong high interacts with low pressure development off Florida, a
stiff NE flow should prevail much of this period into early next
week. This will keep maximums moderated, and notably milder minimums
at and near the coast compared to the interior where low
temperatures this weekend will dip into the 60s in many locations.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
-- Changed Discussion --
As of 17Z...High moisture content along the coast and stronger
heating inland will allow all terminals VCTS through at least
23z. Light winds overnight and partial clearing will aid in
patchy 1-2SM BR and BKN003 between 09z-13z. Light winds this
TAF cycle generally S-SW 8 kt or less, 5 kt or less inland
overnight. VCSH after daybreak Wednesday mainly coastal sites
expanding into TSRA around inland terminals KFLO and KLBT aft
15z. Low level wind shear will be locally strong in and near
TSTMS.

Extended Outlook...Some storms could be locally strong aft 18Z
Wednesday with isolated IFR cond, then MVFR showers and TSTMS
Thursday. Most showers and storms will push offshore with a cold
front Thursday night into Friday. MVFR clouds however of BKN025
could plague coastal terminals in wake of the front in NE flow
of maritime moisture.
-- End Changed Discussion --


&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 10 AM Tuesday...SE waves around 2 feet every 7 seconds
dominate the wave spectrum and this trend will prevail through
this evening. Isolated storms off New Hanover/ Pender counties
will weaken, but we may see regeneration by pre-dawn Wednesday.
A few gusts to 16-17 KT possible inshore 3-6 pm this afternoon
as the sea breeze strengthens a bit.

As of 300 AM Tuesday...The waters will be in between the Piedmont
Trough and Western Atlantic Ridge through tonight. The seabreeze
boundary will sharpen this afternoon as it moves inland into early
eve. Winds speeds across the waters will increase to 10 to 15 kt
late day and remain in that range through the night, being a bit
gusty late day and this eve. The direction will be SW to SSW today
and SW tonight. Seas will be 2 to 3 ft today and 3 to 4 ft tonight.
A SE swell of 9 to 10 seconds will make a significant contribution
to the overall wave heights.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM Tuesday...Southwest winds of 10 to 15 KT are expected
Wednesday and Wednesday night with a turn to a more westerly
direction Thursday.  Thursday night, winds will become NE 10 to 15 KT
but stronger winds are possible as cooler air pushes into the area.
Seas should run 2 to 3 feet through the period though 4 footers are
possible Thursday night depending on the strength of the NE winds.

LONG TERM /FRIDAY THROUGH SATURDAY/...
As of 300 AM Tuesday...This period will become fraught with
challenges for marine activities as a strong Canadian high forces a
cold front across the coast Thursday night. NE winds will begin to
increase Friday as the Canadian high presses SSE over the waters,
and a Small Craft Advisory may be needed for 25 KT gusts and 6 foot
seas offshore. The strong onshore flow will likely persist into
Saturday, as the high interacts with deepening low pressure off
Florida, and thus maintaining rough conditions into the weekend.

&&

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

&&

$$

NEAR TERM...RJD/MJC
SHORT TERM...RAN
lONG TERM...MJC
AVIATION...8