323
FXUS62 KILM 190104
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
904 PM EDT Fri Jul 18 2025

.SYNOPSIS...
Hot and humid weather will persist through Monday as Bermuda
High Pressure maintains a southwesterly wind across the
Carolinas. A cold front arriving Monday could bring increasing
coverage of showers and thunderstorms, followed by slightly
cooler weather Tuesday and Wednesday. Heat could return late
next week.

&&

.UPDATE...
The usual tweaking executed after a round of convection having
ended around sunset. Active SW-WSW winds in the lower levels to
keep boundary layer mixed and therefore keeping any rad fog
to a minimum if at all, even across locations that received
rainfall. Lows mid to upper 70s, around 80 at the beaches.

&&

.NEAR TERM /THROUGH SATURDAY/...
Cu fields have begun to show signs of life early this
afternoon and should lead to widely scattered showers/tstms
through the late afternoon and early evening. HREF indicates
convective activity will trail off after 02Z. Overnight min
temps will only fall to the mid 70s, except upper 70s at the
beaches as surface high pressure off the SE coast maintains warm
and moist SW flow across the area. Synoptic features Saturday
remain largely unchanged from today as a ridge continues to
dominate across the SE CONUS. Guidance continues to point to
widespread mid 90s Saturday, and combined with mid/upper 70s
dewpoints, will necessitate another CWA-wide Heat Advisory. The
heat index will likely touch 110 degrees in a few locations
Saturday afternoon, but only for an hour or two, therefore not
requiring an Extreme Heat Warning. The mid-level ridge will keep
weak ripples in the westerly flow aloft just to our north,
along with better chances for tstms. Across our CWA, PoPs
Saturday will generally range from 20% across NE SC to 40%
across SE NC.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
A 500 mb ridge centered over the Florida Gulf Coast on Saturday
Night should retrograde to the lower Mississippi Valley by
late Monday. Hot temperatures and high dewpoints should
continue across the Carolinas Sunday, likely necessitating
another day of Heat Advisories with afternoon heat indices
expected to reach 105-108 degrees. Sunday`s seabreeze front and
the Piedmont Trough inland should be triggers for isolated
showers and thunderstorms within an airmass with 2000-3000 J/kg
CAPE but with relatively dry mid level humidity.

By Monday the upper ridge should retrograde far enough to allow
northwesterly mid and upper level flow to develop over the
Carolinas. In addition, an upper trough swinging through New
England should help push a surface cold front southward into
the Carolinas during the day. High temperatures on Monday
should again reach the mid 90s with high humidity, likely
triggering yet another Heat Advisory. Enhanced low level
convergence as the front meets the afternoon seabreeze plus
impulses arriving within the northwest flow aloft should help
to develop clusters of showers and thunderstorms Monday
afternoon into Monday night. While we`re not in a Day 4
convective outlook from SPC, it`s possible strong/gusty winds
could develop in association with these storms. The cold front
should gradually work its way offshore Monday night.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The upper ridge should poke north over the Mississippi River
Valley Tuesday through Thursday, perhaps settling back toward
the Gulf Coast again by Friday. Low level northeast flow should
bring slightly cooler air into the Carolinas Tuesday and
Wednesday with highs anticipated to reach 85-90 both days with
maximum heat indices only in the 90s. Uncertainties as to how
far south the front makes it before stalls means I`ll have to
keep a chance of showers and thunderstorms in the forecast
Tuesday despite the GFS showing the arrival of a drier and much
more stable airmass.

The front should gradually wash out just off the Southeast
coast Wednesday into Thursday as the Bermuda High strengthens
offshore. This should gradually veer our surface winds from
northeast to a southerly direction with humidity creeping back
up each day. By Friday it`s possible we`ll have a return to the
same airmass we`re in now with temperatures in the 90s and heat
indices creeping back up to the 105 trigger for Heat Advisories.

Note: although the 12z operational GFS shows a low developing
from the old front and moving onshore Thursday, there is no
support for this solution among the 12z GFS ensembles at this
time.

&&

.AVIATION /01Z SATURDAY THROUGH WEDNESDAY/...
VFR will dominate the 24 hr periodic. Dissipating mid and
upper level clouds to dominate tonight. Boundary layer remains
mixed keeping any rad fog to a minimum if at all. Terminals that
observed rainfall may have a shot for fog but latest
GFSLampGuidance says negative and will lean toward that
solution. Main issue will be prob30 mvfr tstorm chances during
the late morning thru early aftn for the coastal terminals...
and mid afternoon thru early evening for the inland terminals.
Active SSW winds to back to SW-WSW by daybreak and continue
thruout the day with increased speeds. The coastal terminals
will see winds back to the SSW-S at increased speeds once the
sea breeze develops and progresses inland during the
aftn/evening.

Extended Outlook... Isolated/Scattered showers and
thunderstorms may bring brief MVFR ceiling and visibility
impacts this weekend, mainly the afternoon thru early evening
hours. Coverage may increase Mon and Tue as a slow moving
front drops to the Carolinas from the north.

&&

.MARINE...
Through Saturday...SW flow will persist through Saturday
between surface high pressure off the SE coast and a weak
Piedmont trough across the inland Carolinas. Wind speeds will be
on the order of 10- 15 kts with occasional gusts to 20 kts,
particularly this afternoon and again Saturday afternoon as the
gradient tightens up a bit. Shower/tstm chances remain
relatively low this afternoon and overnight, and will tick up a
bit north of Cape Fear late Saturday due to proximity to the
westerly flow aloft and associated weak shortwave energy
crossing NC.

Saturday night through Tuesday...Bermuda High Pressure offshore
will maintain a humid southwest wind across the Carolinas
Saturday night through Monday. A cold front should arrive at the
beaches during the day Monday, however Monday`s daytime
seabreeze should be strong enough to keep the front from
initially pushing out across the coastal waters. We will need to
watch Monday afternoon and Monday night closely for the
development of clusters of gusty thunderstorms which could bring
impacts for mariners. The front itself should finally push
offshore Monday night with northeasterly wind expected to
develop Tuesday into Wednesday. Confidence on the speed of these
northeast winds is not particularly high - the 12z GFS model
has a stronger high building over coastal New England by the
middle of next week and shows our NE winds averaging 20 knots
while the 12z Canadian and 00z ECMWF are in the 10-15 kt range.

There should be a small 8 second southeast swell with us
through the entire forecast period. Dominant waves, however,
will consist of a 5 second southerly wind wave Saturday night
through Monday, then a 5-6 second northeasterly wind wave
Tuesday into Wednesday. Combined seas should average 2-4 feet --
although higher seas could develop Tuesday and Wednesday if the
GFS model is correct with its higher wind speeds.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
NC...Heat Advisory from 11 AM to 8 PM EDT Saturday for NCZ087-096-
     099-105>110.
SC...Heat Advisory from 11 AM to 8 PM EDT Saturday for SCZ017-023-
     024-032-033-039-054>056-058-059.
MARINE...None.

&&

$$

SYNOPSIS...TRA
UPDATE...DCH
NEAR TERM...CRM
SHORT TERM...TRA
LONG TERM...TRA
AVIATION...DCH
MARINE...TRA/CRM