838
FXUS62 KILM 171812
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
212 PM EDT Thu Jul 17 2025

.SYNOPSIS...
Bermuda High Pressure will remain off the coast through this
weekend. Temperatures will increase with a dangerous
combination of heat and humidity developing for Friday through
the weekend. Widely scattered thunderstorms are possible through
Sunday with more widespread coverage by early next week as a
front drops south into the Carolinas.

&&

.NEAR TERM /THROUGH FRIDAY/...
500 mb high pressure centered just east of the Bahamas will
retrograde its way to near the Florida East Coast by Friday
afternoon. Rising mid and upper level heights across the
Carolinas are indicative of a warming airmass and guidance is
pointing at Friday`s temperatures rising another 2-3 degrees
versus today with mid 90s expected for most inland locations.
Given dewpoints expected to mix down only into the 74-77 range
during the afternoon, forecast heat indices of 105 to 108 will
require the issuance of a Heat Advisory running from 10 AM until
8 PM.

GFS and NAM forecast soundings show mid level humidity should drop
further on Friday with the arrival of stronger ridging aloft. Models
were too dry yesterday and again today even as dry air has started
working in aloft, so I`m hesitant to drop PoPs below 20 percent as
suggested by 12z HREF. NBM hourly PoPs of 20 percent along the SC
coast and 30-40 percent elsewhere may work out better given the
recent history of shallow convection in this tropical airmass.

And lastly, another warm and very humid night is expected across the
area with lows ranging from 75 inland to around 80 on the beaches.
Wilmington`s forecast low in the upper 70s should be the 43rd
consecutive night of low temps 70 degrees or warmer this summer.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
The mid-upper anticyclone will be in the process of drifting
westward through this period, keeping dangerous heat and humidity in
the forecast (highs in the mid-upper 90s on Saturday) which will
likely necessitate a Heat Advisory for heat indices in the 105-109F
range (with some isolated 110F possible in the hottest spots).
Subsidence and dry air aloft will keep rain coverage in the isolated
to widely scattered range during this period while a stalled front
and shortwave energy passing through the Mid-Atlantic will likely
result in considerably more precip coverage north of the forecast
area. With surface high pressure drifting westward across Florida,
expect southwesterly winds to continue, helping to keep the sea
breeze nearer to the coast. Overnight lows in the mid-upper 70s are
expected, which are 3-6F above normal.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
As the mid-upper anticyclone drifts further westward into the Gulf,
troughing will dig into the Atlantic. As this occurs, the mid-level
flow will become increasingly northwesterly over the area, opening
the door to convective complexes sliding into the region as
shortwave energy slides down the east side of the ridge. Guidance
appears to be honing in on Sunday evening/night and Monday
afternoon/evening as periods to monitor for convection arriving from
the northwest. Over Monday night into Tuesday, a recent trend in the
guidance is for a stronger backdoor front sneaking further
south/southwest than originally anticipated, leading to a stronger
push of lower-dewpoint air that may be able to knock them below 70F
for the first time in weeks on Tuesday and Wednesday. If this comes
to fruition, which is somewhat hard to believe given the time of
year, deep dry air and subsidence would also arrive, putting an
effective lid on almost all convection on Wednesday. As mentioned
above, although this is a trend amongst the global guidance, it is
hard to believe that a ridge over the Gulf won`t end up stronger
than modeled and thereby limit the backdoor front`s southward
progress. Nevertheless, this will need to be monitored closely.

Conditions will remain hot and humid on Sunday and Monday as the
ridge slowly drifts west with highs in the mid-upper 90s on Sunday
and mid-90s on Monday. Greater cloud cover and precip should limit
daytime highs on Tuesday, although the timing of this potential
backdoor front passage will impact temps and dew points, leading to
low confidence on Tuesday through Thursday at this juncture.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
Clusters of showers and thunderstorms have developed along
today`s seabreeze front extending from Myrtle Beach into
Wilmington. With a westerly component to the background synoptic
winds the seabreeze front will not make much inland progress
today, keeping the convective risk large for KMYR, KCRE, and
KILM through 20-21z today. For the inland airports convective
activity is more isolated and less intense, but brief reduction
in visibility in showers is still possible through 23z before
cooling evening temperatures causes storms to dissipate.

VFR conditions are expected overnight into Friday morning. Cumulus
with cloud bases in the 1500-2500 ft AGL range are expected to
develop after sunrise, perhaps forming brief MVFR ceilings between
13-16z. But the trend should be toward rising ceilings and fewer
convective showers around tomorrow versus the more widespread
activity we see today.

Extended Outlook... Isolated showers and thunderstorms may bring
brief MVFR ceiling and visibility impacts Saturday through Sunday,
mainly the afternoon and early evening hours. Coverage may increase
Monday and Tuesday as a front reaches the Carolinas from the
north.

&&

.MARINE...
Through Friday...The flow between Bermuda High Pressure well
offshore and a cold front sinking as far south as southern Virginia
should help veer winds across the Carolinas a little more westerly
late tonight into Friday morning. There`s a roughly 6 hour period
centered on 9 AM Friday where west-southwesterly winds are expected.
Just like today there`s the expectation a good seabreeze will
develop Friday afternoon turning nearshore winds more southerly with
an increase in speed to 15-20 knots. Scattered showers and
thunderstorms moving quickly northeastward are also expected,
primarily during the morning and early afternoon hours.

Seas should continue to average 3 to locally 4 feet in height with a
6 second dominant wave period. A new 8 second southeast swell will
also develop but with a much smaller amplitude than the wind waves.

Friday Night through Tuesday...
Bermuda high pressure will maintain steady southwesterly flow
through the weekend until a backdoor front approaches from the
north early next week. Depending on if this front drops
through, a northeasterly wind surge may occur in its wake.
Otherwise, winds will weaken as the front draws near on Monday
into Tuesday as the pressure gradient becomes weakly-defined.
Waves mainly in the 2-4 ft range are expected to subside
slightly to 2-3 ft as winds relax over Sunday and Monday.
Depending on the outcome of the northeasterly wind surge, waves
would increase again as winds pick up and have a longer fetch
over the Atlantic on Tuesday. The wave spectrum will be
dominated by southerly wind waves of 2-3 ft with a period of 5
sec and supplemented by 1-2 ft southeasterly swells with a
period around 8 sec.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
NC...Heat Advisory from 11 AM to 8 PM EDT Friday for NCZ087-096-099-
     105>110.
     Beach Hazards Statement until 8 PM EDT this evening for NCZ106-
     108.
SC...Heat Advisory from 11 AM to 8 PM EDT Friday for SCZ017-023-024-
     032-033-039-054>056-058-059.
     Beach Hazards Statement until 8 PM EDT this evening for SCZ056.
MARINE...None.

&&

$$

SYNOPSIS...ILM
NEAR TERM...TRA
SHORT TERM...ABW
LONG TERM...ABW
AVIATION...TRA
MARINE...TRA/ABW