489
FXUS62 KILM 220726
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
326 AM EDT Mon Jul 22 2024

.SYNOPSIS...
Occasional showers and thunderstorms, some with heavy rain,
will continue through the remainder of the week as southerly
winds bring tropical moisture northward. A weak front could
stall near the area this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Showers and thunderstorms likely again today as deep SW flow
maintains a moisture rich environment. Slight perturbations in the
flow aloft and vorticity maxima centered over the central Carolinas
should be more than sufficient for widespread lift this afternoon. A
weak sea breeze will likely spark the initial development of showers
along the coast, progressing inland with some development possible
along the Piedmont trough. Cooler today with early debris clouds and
better rain chances by early afternoon; highs in the upper 80s.

Hi-res model guidance is showing the bulk of this convection will
take shape during the late afternoon and early evening. As we have
seen with previous days, elevated instability has been the biggest
driver of sustained convection and no reason to expect a large
deviation today. It is worth noting that the scale of convection
earlier this morning likely will delay surface heating and could
hinder convective initiation. Still, the ingredients in place
suggest that widespread showers and storms are likely, but still
difficult to focus on a particular area.

While instability decreases this evening, mid level forcing will
continue. This lift is expected to extract all available instability
with showers continuing into the late evening and overnight.
Persistence forecast for coastal areas as onshore flow could push a
few marine showers and storms toward the coast after midnight. Humid
with lows in the mid and upper 70s.

&&

.SHORT TERM /TUESDAY THROUGH FRIDAY/...
The subtropical ridge will remain anchored near Bermuda through
Friday while a series of upper troughs move from the Great
Lakes into New England. Over the Carolinas, this should ensure a
southwesterly upper level flow advecting in deep Gulf moisture
plus a series of subtle upper impulses with attendant convective
enhancement. The low level flow should remain southerly which
will maintain a solid link to Atlantic moisture by way of the
Bahamas. Precipitable water values should remain 2 inches or
higher with surface dewpoints remaining in the 70s.

From a pattern recognition standpoint this setup favors a very
tropical weather pattern with good convective coverage over the
coastal waters during the mornings spreading onshore after sunrise,
then redeveloping inland during the afternoon hours. Traditional GFS
MOS PoPs are 20-30 percent lower than newer NBM guidance through the
period. Splitting the difference yields 50-70 percent coverage each
day, perhaps peaking on Thursday. This is a good pattern to help
alleviate this summer`s drought which was ranked "extreme" (D3) from
Florence to Marion and Whiteville on last week`s U.S Drought Monitor
update.

Due to increased clouds and precipitation coverage, diurnal
temperature ranges will remain constricted in this monsoon-like
pattern. Highs around 90 Tuesday and Wednesday should remain in the
mid-upper 80s Thursday and Friday. Overnight lows should generally
fall into the mid 70s with upper 70s near the beaches.

&&

.LONG TERM /FRIDAY NIGHT THROUGH SUNDAY/...
GFS, Canadian, and ECMWF models show a front sneaking southward
into the Carolinas late Friday night or Saturday morning. This
feature likely won`t make it too far south and may stall across
South Carolina for the weekend. Yesterday`s 12z ECMWF was the
closest model we`ve got showing an airmass change. A more likely
scenario is post-frontal easterly flow off the Atlantic
maintains a sticky humid low level airmass.

In the upper levels the subtropical ridge should begin to redevelop
over the Southeast states as the upper trough that drove the front
south moves out toward Bermuda. This should reduce convective
coverage some, but with the stalled front we`re maintaining "chance"
PoPs for showers and thunderstorms through the period.

Highs both Saturday and Sunday are forecast to reach the upper 80s
with lows 70-75.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Heavy rain continues inland with debris clouds and outflows from
these storms impacting the inland terminals early this morning.
Could see clouds bases drop to to IFR during this time as another
area of dissipating convection lifts across the area.
Southerly flow could see clouds drop to even lower categories before
sunrise, but confidence is low.

Isolated showers and storms likely to impact the coastal areas over
the next few hours as onshore flow pushes convection north and
eastward. Mix of VFR/MVFR clouds during this time with periodic VIS
drops in thunderstorms. TAFs include the potential for a direct
thunderstorm impacts, but confidence is low, especially for the
Grand Strand.

VFR developing early Monday with afternoon thunderstorms again
likely. Storms will generally work their way inland through the
afternoon along the sea breeze.

Extended Outlook...Potential for IFR/MVFR with showers and
thunderstorms each day.

&&

.MARINE...
Through Tonight...No changes from the previous forecast. South
winds at 10-15 knots during the day weaken slightly and become
southwesterly overnight. Gusts up to 20 knots during the day as a
weak sea breeze develops. SE swell continues at 2-3 feet at 9
seconds.

Tuesday through Friday Night...A warm and humid weather pattern will
continue across the Carolinas with Bermuda High Pressure remaining
well offshore. South-southwest winds (strongest Tuesday afternoon
through Wednesday at a solid 15 knots) are expected through the
period. Tropical moisture lifted north out of the Bahamas will
maintain scattered showers and thunderstorms across the coastal
waters with the most extensive coverage anticipated during the
morning hours. We`re not expecting a washout on any particular day,
but convection should be widespread enough to present a marine
weather challenge.

Confidence is not particularly high yet, but by late Friday a cold
front could advance far enough south to begin impacting wind
directions, potentially turning them west to northwest.
&&

.ILM WATCHES/WARNINGS/ADVISORIES...
NC...Coastal Flood Advisory from 10 PM this evening to 1 AM EDT
     Tuesday for NCZ107.
SC...None.
MARINE...None.

&&

$$

SYNOPSIS...TRA
NEAR TERM...21
SHORT TERM...TRA
LONG TERM...TRA
AVIATION...21
MARINE...TRA/21