Myrtle Beach, South Carolina 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

671
FXUS62 KILM 211010
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
610 AM EDT Wed May 21 2025

.SYNOPSIS...
A cold front will move across the area tonight, with isolated
storms possible along the coast this afternoon. Slightly cooler
and less humid air is slated for Thursday into the weekend.
Unsettled weather may return late Sunday into next week.

&&

.UPDATE...
Updated the forecast to adjust timing and location of showers
and thunderstorms moving into the forecast area. Southern end of
the line has begun weakening and the mid-level forcing driving
is slipping a bit further north. This will allow for weakening
of any cells moving across southeast NC during the next few
hours as somewhat deeper convection shifts north of the forecast
area. Any showers that do persist will move off the coast around
0800 EDT.

&&

.NEAR TERM /THROUGH TONIGHT/...
Warm front has pushed north of the forecast area with weak low
pressure along the boundary gradually becoming more defined
across central NC. The low has resulted in winds veering from
southeast to southwest the last few hours. The shift to
southwest also brings about a surge of drier low level air.
Humidity at 925mb drops off significantly once the southwest
winds develop. The low level drying and winds 5-10 mph have been
able to clear out any fog or low clouds that have developed.

Broken line of convection moving into central NC this morning
is associated with a pre-frontal trough. The line will be moving
into a less favorable low level environment and the mid-level
dynamics helping drive the storms will be shifting off to the
north. Nearly all of the guidance (including the high resolution
CAMs) show much of the convection collapsing before reaching
the forecast area around daybreak. Would not be shocked if some
remnant light rain/weakening showers move east-northeast across
the region after entering the forecast area around 10Zish, but
most areas will stay dry. This trough continues east across the
region, moving offshore before any real instability can develop.
The only spots that may be able to develop any deeper
convection would be along the immediate coast, where the pinned
sea breeze and a narrow window of SBCAPE AOA 2500J/kg will
coexist as the trough arrives. The catch will be how quickly
does the mid-level environment become unsupportive of deeper
convection. Mid-level subsidence starts increasing between
15z-18Z inland and around 18Z along the coast, so the window for
convection to initiate and get going will be 16Z-19Z at best.

Approaching cold front and daytime heating both lead to an
increase in the gradient today with southwest flow around 15 kt
likely. Low level jet over 30kt this morning lifts north before
mixing gets going, so not expecting much more than gusts around
20 kt in the afternoon. Temperatures well above normal today
with clearing skies, subsidence and strong west to southwest
flow. The sea breeze will hang close to the coast today and
widespread 90s seem like a given with potential for mid 90s in
some areas.

The cold front pushes offshore tonight with west-northwest
winds developing as high pressure builds in. Cool and dry high
pressure arriving overnight with winds helping to keep lows in
the mid 60s despite 850 temps dropping 5C from 00Z to 12Z.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Dry and mostly sunny during the day Thursday with cold front
well offshore by morning, with highs in the mid 80s. Mixing
heights will be quite high, almost 9 kft, which could mix down
gusts of 30+ mph Thursday afternoon. Deep mixing will also bring
down low dewpoints, with minimum RH currently forecasting
around 30%. A second frontal passage Thursday night, combined
with PVA aloft rounding base of longwave trough over the
Northeast, may produce a few light showers late Thursday with
perhaps isolated thunder with meager elevated instability.

Quiet on Friday as surface high pressure briefly moves in and
mid level ridge builds over the Southeast as low pressure system
to the north moves off to the NE. Slightly cooler and drier
Friday with highs around 80F. Lows around 60F Thursday night
will drop to low to mid 50s Friday night, almost 10 degrees
below normal.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Mid-level ridge, and associated subsidence, maintains control
Saturday into (at least) early Sunday with persistent upper
trough over the Eastern US finally exits into the Atlantic.
Below normal temps continue Saturday, with slight warming trend
into Sunday. The next system looks to develop over the South on
Sunday, moving across the Southeast early next week. Low
confidence in timing and strength/position of the mid-level
ridge continues to yield plenty of uncertainty in the forecast
beginning late Sunday - for now, have increasing pops in the
forecast for next Monday and Tuesday.

&&

.AVIATION /10Z WEDNESDAY THROUGH SUNDAY/...
Weakening showers and thunderstorms moving across may bring
brief MVFR/IFR to LBT prior to TAF time and potentially MVFR to
ILM around 12Z. Confidence in impact from these weakening cells
is low.

Although an isolated shower or thunderstorm will be possible
around midday along the coast, the environment is not favorable
for storm development. Confidence in VFR is high for inland
sites. Along the coast confidence in VFR through 18Z is
moderate increasing to high after 18Z. A cold front will move
across the area this evening, shifting winds to northwest
overnight. LLWS could be an issue tonight as strong winds just
above the surface develop.

Extended Outlook...High confidence in VFR Wednesday night
through Sunday.

&&

.MARINE...
Through Tonight...South to southwest winds will increase over
the waters today ahead of an approaching cold front. Brief
period of southwest winds 15-20 kt possible this afternoon, but
duration is short enough that seas will peak at 3-5 ft. An
isolated gust to 25 kt is possible, but the more stable marine
air will limit mixing of the strong wind aloft to the sea
surface. No plans for a SCA today or tonight, but well away from
shore conditions this afternoon and evening will approach
headline criteria. Cold front moves offshore tonight, moving
east of the waters by midnight. Offshore flow quickly weakens as
the gradient relaxes and northwest flow will be 15 kt or less
by Thu morning. After peaking at 3-5 ft late afternoon and
evening seas quickly subside, dropping to 2-4 ft by daybreak
Thu. Seas will be a mix of a dominant southerly wind wave and a
southeast swell.

Thursday through Sunday...Northwest winds early Thursday,
behind initial cold front, will once again turn southwesterly
for Thursday afternoon as a second front approaches the area
with wind speeds near 20 kts. Winds will return to west-
northwesterly at 10-15 kts Thursday night through early
Saturday. Brief high pressure will make winds lighter and more
variable Saturday into Sunday before southerly winds develop
late Sunday. Seas 2-4 ft Thursday and Thursday night lowers to
2-3 ft Friday & Saturday, and further improves to 1-2 ft Sunday.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement through this evening for NCZ106-108.
SC...Beach Hazards Statement through this evening for SCZ054-056.
MARINE...None.

&&

$$

SYNOPSIS...ILM
UPDATE...III
NEAR TERM...III
SHORT TERM...VAO
LONG TERM...VAO
AVIATION...III
MARINE...III/VAO