898
FXUS62 KILM 121828
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
228 PM EDT Sat Sep 12 2026

.WHAT HAS CHANGED...
Forecast PoPs have been reduced this afternoon into this evening
as various inhibiting factors are preventing widespread storms
from forming. Models are trending cooler with the incoming
Canadian airmass Monday night through Wednesday.

&&

.KEY MESSAGES...
1) Deep Gulf moisture and a break in the ridge aloft will
maintain good chances for showers and thunderstorms through
Sunday.

2) A modified Canadian airmass should bring cooler temperatures
beginning Tuesday.

&&

.DISCUSSION...
KEY MESSAGE 1...Deep Gulf moisture and a break in the ridge
aloft will maintain chances for showers and thunderstorms
through Sunday.

Forecast convective development today has been scaled back
significantly compared to what NBM and synoptic models were
suggesting over the past 2-3 days. On a broad scale the culprit
may be subsidence from persistent offshore convection. On a
more local scale, persistent mid level clouds inland, subsidence
behind a subtle shortwave lifting northward across North
Carolina, or the lack of strongly convergent surface boundaries
could be to blame. Forecast PoPs through early evening have
been scaled back to only 30-40 percent which is still higher
than most of the recent CAMs suggest.

For any storms that do manage to develop this afternoon, the
airmass should still support locally heavy rain given slow cell
motion and anomalously high precipitable water values near 2.25
inches.

CAMs suggest new showers and thunderstorms may begin to develop
across the coastal waters around midnight. Mid level winds
would tend to bring these northeastward where they could drop
rain across portions of Brunswick and New Hanover counties late
tonight into Sunday morning.

Sunday`s daytime seabreeze front may be the focus for additional
scattered showers and storms. The mid level flow will veer more
westerly on Sunday as a shortwave moves eastward across the
Carolinas. Bulk shear should also increase to 15-20 kt which
may lead to multicell storms redeveloping along boundaries like
the seabreeze front. Drier conditions developing aloft inland
during the afternoon should tend to reduce coverage of showers
or storms there.


KEY MESSAGE 2...A modified Canadian airmass should bring cooler
temperatures beginning Tuesday.

The strongest Canadian high, 1030 mb, we`ve seen since last
spring will move eastward across southern Quebec and New England
Monday through Tuesday, pushing a cold front southward. Models
are in excellent agreement showing the boundary will push
across Cape Fear early Monday evening, racing southward past
Myrtle Beach and Georgetown before midnight.

Modified Canadian air will spread southwestward behind the
front Monday night, scouring out the excessive humidity and
unseasonable warmth of the past week. Given the long path over
75-85 degree water off the East Coast, this won`t feel like a
crisp fall airmass although it will be cooler and drier.

Forecast highs Tue-Thu should hold in the 80s, close to normal
for this time of year. The big improvement will be with
nighttime lows: models have continued to trend lower each run
and now show some potential for upper 50s in spots inland
Tuesday night. Dewpoints in the 50s and 60s will feel very
refreshing.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
Scattered showers and thunderstorms are expected to develop
across this afternoon in an unseasonably warm and humid airmass.
Triggers for storm development should include the seabreeze
front pushing inland from the beaches, and differential heating
along the edges of the persistent mid level cloud deck inland.
Coverage should average 30-50 percent of the area this afternoon
which explains the PROB30 group for the coastal airports and
the TEMPOs inland. Convection should diminish in coverage around
sunset.

VFR conditions overnight will likely become interrupted by low
stratus developing at KLBT and KFLO late tonight, mainly after
09z. This cloud cover should linger through 14-15z Sunday
before mixing out into VFR conditions during the late morning.
Along the coast, high-res models suggest marine convection
streaming northeastward could affect the KILM airport after
sunrise. Sunday`s seabreeze front could also be a potential
focus for new showers or storms affecting KMYR and KCRE mainly
after 16z.

Extended Outlook... Scattered showers and thunderstorms
bringing brief MVFR/IFR conditions are expected to continue
into Saturday evening. Some showers are possible on Sunday, but
coverage should be less than previous days. There is also a low
potential for late night/early morning stratus or ground fog
affecting KLBT and KFLO late Saturday night and again late
Sunday night. VFR conditions should prevail Monday through
Wednesday as a more stable and drier Canadian airmass builds in
from the northeast.

&&

.MARINE...
Tonight through Thursday...Aside from anticipated waves of
showers and thunderstorms developing late tonight into Sunday
morning, then additional isolated showers/storms Sunday
afternoon along the seabreeze front, marine weather conditions
won`t be too bad for the next couple of days. Synoptic winds
from the southwest should average 10-15 knots with seas
averaging 2-3 feet in a mixture of wind chop and a 9 second
southeasterly swell.

Big changes should arrive Monday evening as a cold front sweeps
quickly across the area from the north. A surge of
northeasterly winds should follow the the front, driven
southward by the strongest Canadian high we`ve seen since last
spring. Northeast winds 15-20 knots, occasionally reaching 25
knots at times, should develop Monday night and persist through
Wednesday. There`s better than 50-50 chances wind/wave
conditions will necessitate a Small Craft Advisory beginning
Monday evening.

&&

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

&&

$$

WHAT HAS CHANGED...TRA
KEY MESSAGES...TRA
DISCUSSION...TRA
AVIATION...TRA
MARINE...TRA