061
FXUS62 KILM 200528
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
128 AM PM EDT Sat Jul 20 2024

.SYNOPSIS...
Seasonable temperatures and good chances for showers and
thunderstorms will continue for most of the next seven days as
Bermuda High offshore and the Piedmont Trough inland remain
nearly stationary.

&&

.UPDATE...
A wave of convection will move northeastward across the area
this evening, dropping locally heavy rainfall. Even though this
may be the second or even third wave of storms for some areas
today, surface-based instability is not necessary: given the
great depth of moisture Showalter indices (essentially the LI
using 850 mb for the initial parcel) are -2 to -3 and should
easily sustain convection for hours to come.

The best rain chances should exist across the Pee Dee and Grand
Strand regions now through 1 AM. Storms should wrap up in the
Cape Fear area after 3 AM. This convection is linked to an upper
level disturbance currently moving across western South
Carolina.

Changes with the forecast this evening related mainly to hourly
timing of the highest PoPs which range from 50 percent
(Georgetown-Myrtle Beach) to as high as 80-90 percent across the
Pee Dee/I-95 corridor. I`ve maintained patchy fog inland as
there should be widespread development of low stratus late
tonight behind the storms.

&&

.NEAR TERM /THROUGH SATURDAY/...
Latest surface analysis shows a cold front just north of the local
forecast area. This front has worked along with the Piedmont trough
and the seabreeze to spawn some sparse convection over the area so
far, with more to come over the next several hours. While no severe
weather is expected, some storms may become strong at times, with
wind gusts up to 40-45 mph, small hail, and frequent lightning.
Still have plenty of water in the column, with precipitable water
values routinely climbing above 2 inches. However, the mid-levels
aren`t as saturated, and Corfidi downshear vectors are rather fast.
Locally heavy rain is certainly possible in some spots, but
especially considering the drought, we shouldn`t have any widespread
flooding issues to worry about. Convection wanes a bit late this
evening after solar insolation decreases, but rain chances remain
near the coast. Lows tonight in the low-to-mid 70s.

Weak cold front tries to edge a bit closer to the area Saturday.
This kicks up the rain chances even more, aided by better forcing
aloft from shortwaves traversing through the area from the
southwest. This puts the kinematics in better shape compared to
today, allowing for a "Marginal Risk" (threat level 1/5) of severe
weather, particularly closer to the coast. While shear is still on
the weaker side, it does poke up just enough to warrant a damaging
wind threat in multicell thunderstorms. Highs in the lower 90s.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
Still looking at vort-laden southwesterly mid level flow and a front
stalled in the area. On the downside this means widespread showers
and storms that will be hard to pin down timing and location-wise,
the upside is that most places should get more drought releif.
Temperature deviations from climatology will be minimal through the
period.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
An admittedly rare July forecast with very elevated rain chances
through most of its duration. The front from the near/short term
will no longer be the culprit as it will have washed out. The
deviation from the normal pattern (more ridging/higher heights
aloft) will be the continued deep southerly flow; southeasterly in
the low levels and southwesterly above. This prevents any of the
antecedent deep layer moisture from being scoured out. Most of the
long term will feature PW values from 2.0-2.3", which are the 90th
percentile and daily maxima for the dates.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Showers and storms associated with a passing upper level disturbance
should end over land shortly.  Some guidance shows the development
of IFR cigs and some fog in the wake of it, particularly inland.
Once cigs lift after sunrise, expectations for the valid taf period
remain the same as the past several days with VFR expected to
dominate with brief MVFR/IFR interruptions due to passing
convection, mainly in the afternoon and evening.

Extended Outlook...There is continued good potential for
visibility reduction from heavy rain in showers and
thunderstorms each day through next Wednesday.

&&

.MARINE...
Through Saturday...SSW to SW winds at 10-15kts continue through this
period. Seas linger at 2-3ft, with a combination of wind waves and a
smaller southeasterly swell that clocks in at 8-9 seconds.

Saturday night through Wednesday... Very little deviations from
south to southwesterly winds with the Bermuda High and Piedmont
trough in semi-permanent positions. With speeds generally 10-15kt
winds waves will run 2-3 ft, while a small SE component will yield a
dominant wave forecast of 3-4ft for most of the period.

&&

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

&&

$$

SYNOPSIS...ILM
UPDATE...TRA
NEAR TERM...IGB
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...31