Area NWS Forecast Discussion
000
FXUS62 KILM 170712
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
312 AM EDT Tue Jul 17 2018

.SYNOPSIS...
Moisture and rain chances will continue to increase ahead of a
cold front that will move into the area tonight. After a break
in the showers around Thursday, the front and its moisture will
return on Friday and linger over the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 3 AM Tuesday...Water vapor imagery really tells the story
this morning with a wide swath of moisture laden air across the
southeast with a retreating area of drier mid level air across
North Carolina. Several shortwaves will traverse the developing
trough over the next couple of days with the first one occurring
right now. Although the convection is decreasing with this
feature, it will serve to prime the column for showers and
thunderstorms today and tonight. Its certainly not going to rain
all the time but the best forcing with more or less agreement
with the guidance occurring late morning along coastal areas and
this afternoon across inland zones. Another shortwave moves
across tonight which should serve to enhance activity along the
coast. Little in the way of severe potential with lack of shear.
The higher threat and one we along with WPC have been
highlighting for several days is the flooding threat. With PW`s
well over two inches and slower storm motions any activity is
fair game for flooding issues. Essentially no changes to the
temperature forecast.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 3 AM Tuesday...Slow moving cold front will be in the forecast
area as the period begins. Front ends up stalled Wed before
northwest push late Wed night into Thu helps move the boundary off
the coast. Front will be in a very moist environment, precipitable
water will be in excess of 2 inches for much of Wed and Wed night.
At times precipitable water will approach 2.4 inches, a realm
typically reserved for tropical systems and about the highest on
record for July 18 based on SPC climatology. Weak diurnal
instability, forcing along the front and a warm cloud layer in
excess of 14k ft suggest plenty of rainfall potential. Initially
storm motion is over the magical threshold of 10 kt, but by Wed
afternoon and evening storm motion will be under 10 kt, and possibly
dropping below 5 kt. Flooding will continue to be a concern Wed and
Wed night. Highs Wed will run near to slightly below climo while
lows run above climo.

Weak shortwave passing just north of the area a little after
daybreak Thu helps push the front off the coast and allows drier air
into the region. Precipitable water drops under 1.5 inches, which is
about 0.25" below the mean for mid July. Storm coverage will
decrease, especially with weak post wave subsidence and a lack of
forcing. Still think diurnal instability will generate some
convection, but mid-level dry air will lead to a drastic decrease in
precip chances. However, storms that do develop will be very slow
moving, less than 5 kt and if areas that end up with significant
rainfall Tue and Wed experience a slow moving storm on Thu flooding
will again be a concern. Moisture aloft slowly starts returning Thu
night, but low level northeast flow should limit nocturnal
instability and precip chances Thu night will be in the chc/slight
chc realm. Highs will again be near to slightly below climo while
lows will dip a little on the back of drier air. Thu night temps
will be near to slightly below climo.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 3 AM Tuesday...Mid level trough in the Great Lakes starts
reloading on Friday and the front and its associated
moisture/rain should return (quite heavily according to the
ECMWF, more tempered and only coastal according to GFS- the
former now the favored solution). The confluent/digging nature
of this upper wave will keep us in the deep moisture as well as
the warm sector of the surface system. Rain chances will persist
as will the chance for some appreciable rainfall amounts.
Despite the extensive cloud cover for most of the period
temperature guidance is showing temperature deviations from
climatology as being minimal.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
As of 06Z...Increased convection will be the theme for the
aviation community through the period. Intervals of showers and
thunderstorms will move and or develop across all sites through
the period. As usual, confidence is not quite high enough to
address with prevailing groups but the more favored times seem
to be around 15 UTC along the coast later this afternoon inland.
Overall forecast has VFR conditions but there will certainly be
short bursts of MVFR and even IFR conditions with the heavier
activity.

Extended Outlook...Occasional MVFR to IFR conditions due to
scattered to numerous showers and TSTMs.

&&

.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 3 AM Tuesday...Winds are better defined this morning than
they have been in some time basically from the southwest in a
range of 10- 15 knots. This trend will continue through the
period with speeds increasing to a healthy 20-25 knots, at least
for a few hours later this evening. This will increase seas to
3-5 feet from the current 1- 3 feet. A small craft advisory is
possible but with the fleeting nature of possible six foot seas
will hold off for now.

SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 3 AM Tuesday...Bermuda High off the coast at the start of
the period is shifted east-northeast Wed into Thu. Slow moving
front in the area on Wed moves east of the waters for Thu.
Gradient follows a slow but steady weakening trend Wed into Thu
with southwest flow 10 to 15 kt at the start of the period
dropping under 10 kt by Wed evening. Light and variable winds
Wed night become northeast Thu and increase to a solid 15 kt as
northeast surge develops. Seas trend down from 3 to 4 ft Wed to
3 ft Wed night however, the increase in northeast flow Thu
pushes seas back to 3 to 4 ft Thu and Thu night.

LONG TERM /FRIDAY THROUGH SATURDAY/...
As of 3 AM Tuesday...No significant increase in wind or waves
through the period and we shall stay below advisory or headlines
criteria. There is still some uncertainty however regarding
wind direction. The period will start with a front south of the
area slowly lifting north across the area. As this happens the
flow will veer from easterly to southerly.

&&

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

&&

$$

NEAR TERM...SHK
SHORT TERM...III
LONG TERM...MBB
AVIATION...SHK

NWS ILM Office Area Forecast Discussion