321
FXUS62 KMHX 241958
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
358 PM EDT Tue Sep 24 2024

.SYNOPSIS...
High pressure will remain anchored to the north through midweek as a
warm front approaches eastern North Carolina from the west and
stalls. TC Helene will pass through the Southeast US and bring
a period of heavy rain and gusty winds to the area.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 345 PM Tue...Latest analysis shows mid-level ridge
cresting over eastern NC this afternoon as a deep trough with
multiple embedded shortwaves digs into the MS River Valley. The
ridge is forecast to drift further offshore through the short
term but still remain a dominant feature over the region as the
aforementioned trough digs further into the southeastern CONUS
and eventually cuts off. At the surface, a warm front currently
west of Highway 70, abutting high pressure to our north.

Shower activity from this morning has quickly collapsed as it
hit dry air to the east, and with some clearing behind the front
temps have managed to rise into the low 80s across the coastal
plain with Tds in the low 70s. The airmass is supportive of a
few isolated showers and an isolated thunderstorm mainly west
of Highway 17, and continue to carry a chance PoP across these
zones. The forecast tracks closely to the NAM, which was the
best performer with this morning`s convection.

Any activity will fall apart after sunset, giving way to partly
to mostly cloudy skies as the moist airmass expands over the
entire FA. Like last night, some spotty showers are possible
across the coastal plain as weak shortwave energy lifts across
the Carolinas. Clouds keep temperatures mild, in the upper 60s
to low 70s.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/...
As of 345 PM Tue...Warm front will gradually lift northward into
Virginia tomorrow. Upper ridge will remain offshore but will act
to shunt passing shortwave energy to the west, keeping the
region sheltered from more robust precipitation. CAMs do hint at
a recurrence of some spotty showers and thunderstorms, and
although confidence is low opted to put in a broad slight chance
PoP to account for this risk. Any activity will be spotty, but
with PWATs of 1.5-1.75" and CAPEs around 1000 J/kg there is a
risk of heavier rainfall in stronger activity. Highs rise with
an increase in low-level thicknesses, hitting the mid 80s inland
and around 80 along the coast.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
As of 200 AM Tuesday...

 - Above normal temperatures mid-week

 - Watching the tropics late Thursday into Friday

Thursday-Friday: The main item of interest during this time
will be the track of Potential Tropical Cyclone #9. 00z
deterministic and ensemble guidance continue to be fairly well
clustered on an inland track through the Southeast U.S. after
making landfall along the Gulf Coast of Florida. The most
notable change is a slight eastward shift noted in the ensemble
mean track. Based on the latest available guidance, it appears
that we`re getting some clarity on what the impact to ENC may
be. If the current forecast track from the NHC holds, ENC will
remain well east of the center of circulation. However, strong
moisture advection east of the center should allow a plume of
tropical moisture to quickly overspread the coastal Carolinas
Thursday night into Friday. At the same time, a broadly
diffluent flow aloft plus increasing WAA should support a period
of strong forcing, leading to a quick period of moderate to
heavy rain and scattered thunderstorms. While quick-hitting,
guidance has been showing a consistent signal for heavy rain
focused on Thursday night and Friday for at least a portion of
ENC. Instability is forecast to be low, but strong
shear/helicity to the east of the tropical system will need to
be watched for a conditional tornado risk.

Additionally, a strengthening pressure gradient, modest mixing, and
a strong southerly LLJ should allow a period of gusty winds to
accompany the rain and thunderstorms on Friday. This will especially
be the case along the coast. With the subtle eastward shift in the
guidance, winds and precip have increased some compared to the
previous forecast. While this currently appears to be a quick-
hitting scenario for ENC, it has been very wet of late, so it may
not take as much rain to cause some hydro issues.

What`s outlined above appears to be the most likely scenario based
on the latest NHC track and model guidance. Stay tuned, though, as
any shift west, or east, would lower or increase the impacts,
respectively.

Saturday-Tuesday: In the wake of the tropical system, a backdoor
cold front is forecast to move through ENC on Saturday, and may be
accompanied by a few showers. Temperatures will take a step down as
well. By early next week, a surface low may develop off the coast of
ENC as the Mid-South cutoff low finally opens up and moves east
towards the Southeast U.S. coast. This is several days out, but is
worth noting as it could bring another round of gusty winds and
heavy rainfall.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
SHORT TERM /through 18z Wed/...
As of 155 PM Tue...Primarily VFR conditions in place across area
terminals as a warm front lifts northeastward across the region.
Associated bank of showers and storms has fallen apart as it
hits drier air, but showers and a few storms remain possible
this afternoon across the coastal plain as a more moist and
unstable airmass fills in behind the front. This threat is
diurnal, and by nightfall the risk of showers will be low (10%
or less) although a couple offshore showers may threaten MRH and
vicinity. Low stratus is possible across the coastal plain early
AM. VFR will return by late Wed AM.


LONG TERM /Wed through Sat/...
As of 200 AM Tuesday...

 - Watching the tropics late Thursday-Friday

SCT SHRA and TSRA may be ongoing Wednesday morning, but a general
lull in TSRA activity is expected for most of Wednesday and
potentially even into Thursday. Thursday night into Friday, a
tropical system is forecast to pass well west of eastern NC, but
still be close enough to produce a period of gusty winds, RA, TSRA,
and sub-VFR conditions. Sub-VFR conditions and SHRA may linger into
Saturday.

&&

.MARINE...
SHORT TERM /Through Wednesday/...
As of 350 PM Tue...Seas continue to outperform guidance north
of Cape Hatteras, still sitting at 7-8 feet as swell from a
distant offshore low continues to roil the Atlantic. South of
Hatteras, seas remain at 2-4 feet. Northeast to easterly winds
remain at around 10 kt ahead of an approaching warm front.

The warm front is expected to lift north through tomorrow as
winds veer from northeasterly to southeasterly through tonight
and into Wednesday morning, still holding at around 10 kt. The
low responsible for the northeasterly swell will continue to
drift further eastward, and waves will finally fall below 6 feet
for waters within 10 nm. However, seas will likely be at or
exceed 6 feet for outer zones and a SCA remains in effect for
the short term.

LONG TERM /Wed through Sat/...
As of 200 AM Tuesday...

 - Elevated seas mid-week

 - Watching the tropics late-week

Elevated seas continue across the coastal waters mid-week,
especially north of Cape Hatteras, thanks to a persistent
northeasterly long-period swell. Winds will remain relatively light
during this period, though, and range from 5-15kt. Late Thursday
into Friday, we`ll be closely monitoring a potential tropical system
that is forecast to move inland across the Southeast U.S. The latest
guidance keeps this system well west of ENC. However, a strong
gradient east of the system should support a period of moderately
impactful winds and seas. With this forecast update, we`ve increased
winds Thursday night into Friday, and are now showing a period of 15-
25kt south to southeast winds. Recent guidance suggests some 30-35kt
wind gust potential, but this is highly dependent on the track of
the tropical system, so stay tuned. For now the key message is to
plan ahead for gusty winds and building seas, with the impacts
focused on Friday.

&&

.TIDES/COASTAL FLOODING...
As of 400 PM Tuesday...

The coastal flood threat continues for all of coastal North Carolina
into Wednesday as tide levels remain elevated. This includes
the added Neuse, Bay, Pamlico, and Pungo Rivers, where waters in
Belhaven have only recently receded. Water levels at high tide
tomorrow will be slightly lower than yesterday, but could still
result in up to a foot of inundation above ground level. Along
and north of Ocracoke, persistent northeasterly swell from a
distant low offshore will continue to bring minor overwash
concerns with maximum inundation around 1-2 feet.

Looking ahead, we`ll continue to closely monitor the track of
TC Helene as distant coastal impacts could be felt across a
portion of ENC thanks to increasing southerly onshore winds.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Coastal Flood Advisory until 5 PM EDT this afternoon for
     NCZ080-094-194>196-199-203>205.
     Beach Hazards Statement until 8 PM EDT this evening for NCZ203-
     205.
MARINE...Small Craft Advisory until 2 PM EDT Saturday for AMZ150-152-
     154.

&&

$$
SYNOPSIS...MHX
NEAR TERM...MS
SHORT TERM...MS
LONG TERM...RM/RCF
AVIATION...RM/MS/RCF
MARINE...RM/MS/RCF
TIDES/COASTAL FLOODING...MHX