344
FXUS62 KMHX 260558
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
158 AM EDT Thu Sep 26 2024

.SYNOPSIS...
The upper ridge will move little today but the pattern is becoming
progressively more unsettled as Hurricane Helene lifts across
the eastern Gulf of Mexico and into the southeastern CONUS.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
As of 2145 Wednesday...Meridional flow pattern in place across
the eastern CONUS tonight as upper ridge remains anchored off
the coast of the Carolinas, while a deep upper trough digs into
the MS River Valley. The ridge will not move much through the
short term. The trough, which has dug further into the
southeastern CONUS, is beginning to cut off over IL/IN, which
can be seen on satellite with upper level moisture beginning to
circulate around the low. This upper cut off low and offshore
ridging will be Helene`s guides into the Florida Panhandle and
inland over SEern CONUS.

Locally, shower activity has ceased and is expected to remain
quiet through the overnight period but with increasing clouds
as cirrus from distant TC Helene begins to overspread the
region. An early morning shower threat remains for the southern
coastal counties like this morning as trough moves little
offshore. Cloud cover keeps low temps elevated at around 70
inland, and low to mid 70s for area beaches.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
As of 345 PM Wed...Isolated to widely scattered shower threat
will continue Thursday in southeasterly surface flow in tandem
with weak WAA, in the absence of any frontal boundary. Like
today, upper ridge will continue to provide some mid-level
subsidence and keep activity from blossoming into deeper
convection. Therefore, rainfall amounts should remain light at a
quarter inch or less. By early evening, heavier showers
emanating from the outer bands of TC Helene may briefly impinge
on the inner coastal plain.

Warm and muggy tomorrow, with highs in the low to mid 80s.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
As of 4 AM Wed...

Friday/Friday Night...The main item of interest will be the
impacts from TC Helene, which the center of the storm will be
moving through GA and then into the TN Valley. With the large
size of the system, some outer rain bands will be propagating
through ENC during the day. 25/00z deterministic and ensemble
guidance in good agreement with the track of the system. Strong
moisture advection east of the center should allow a plume of
tropical moisture to quickly overspread the coastal Carolinas
throughout the day from w to e. 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, some of which may become
severe and contain a few tornadoes. MLCAPE vals inc to aoa
1,500 J/KG with plume of mid/upr 70s TD`s overspreading the
region. Strong backing of sfc winds to the SE will produce
enhanced low lvl helicity, and a favorable environment for a
tornado or two will develop. While quick- hitting, guidance has
been showing a consistent signal for a brief period of heavy
rain and localized flooding, though the good news is the band or
bands of heavy rain will be progressing eastward fairly
quickly, with rain ending as early as mid afternoon for many
areas save for the OBX, and all areas by day`s end. Attm, 0.75"
to 1.00" are forecast, with locally higher amounts in heavier
cells. Breezy conditions will be present as well, with sserly
breezes gusting to 20-25 mph inland, with 25-30 mph close to the
coast. Quick drying with all rain ending and winds diminishing
rapidly and becoming swrly Fri evening, with temps still muggy
in the low 70s.

Saturday...Mainly dry with subsidence in place behind the
system, and upr low pres well west of ENC. Warm and humid
continues with swrly flow, and highs in the mid 80s.

Sunday through Tuesday...Aforementioned upr low migrates slowly
eastward, with chances for showers each day, with perhaps a
surface low developing near or over ENC. Have capped pops at 30%
attm due to uncertainty on synoptic and mesoscale features this
period. Temps will cont to near or slightly above climo, with
highs in the low/mid 80s to 60s for lows.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
SHORT TERM /through today/...
As of 2 AM Thursday...Conditions are expected to remain
predominantly VFR through the overnight hours. The inner coastal
plain is the area most likely to experience MVFR visibilities
and ceilings, so a MVFR TEMPO group has been added for PGV
between 8-12Z. Low clouds around 3-4 kft will linger today with
isolated to widely scattered showers possible for the western
half of the FA. The signal for sub-VFR flight cats becomes much
greater at the end of the TAF period, which will be accompanied
by greater PoPs and gusty winds.

LONG TERM /Thu through Sun/...
As of 4 AM Wed...A few iso to sct showers will dot the region
on Thu with onshore serly light winds. On 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 end by late Fri afternoon into
evening as dry air moves in behind the system.

&&

.MARINE...
SHORT TERM /Through Thursday/...
As of 345 PM Wed...Seas continue to slowly fall under as light,
5-10 kt southeasterly winds remain behind a departing warm
front currently in Virginia. Seas are sitting at around 5 feet
north of Cape Hatteras, but 2-3 feet south. Little change in the
overall weather pattern is expected as southeasterly winds
persist into Thursday, but winds will begin to increase late
Thursday, especially across Raleigh and Onslow Bays, as TC
Helene makes landfall in the northeastern Gulf Coast and pinches
the pressure gradient.

No changes were made to SCAs from the previous forecast.

LONG TERM /Thu through Sun/...
As of 4 AM Wed...Building seas occur on Thu ahead of TC Helene
well south and west of ENC, and have added the remaining ctrl
and srn waters into the SCA suite, with seas building to 6+ ft
Thu morning. On Fri, gradient inc to 20-25 kt sustained and
gusts to 30 kt for the coastal waters, esp ctrl and srn waters,
and seas build to 7-10 ft with the sserly winds. Attm it appears
winds will remain below gale/trop storm force, though the large
wind field will cont the high seas into Fri evening. Winds
quickly diminish and turn swrly Fri night and cont into Sat with
seas subsiding to below SCA by Sat afternoon.

&&

.TIDES/COASTAL FLOODING...
As of 4 PM Wed...The coastal flood threat continues for all of
coastal North Carolina through tomorrow as tide levels remain
elevated, including the Neuse, Bay, Pamlico, and Pungo Rivers as
reported water levels remain elevated. Water levels will
continue to trend slightly lower, but will still remain high
enough to result in up to a foot of inundation. Along and north
of Ocracoke, swell offshore is weakening but may still result in
some minor overwash where dune structures are compromised or
vulnerable.

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 on Fri into Fri evening thanks to southerly
onshore winds and large waves.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Coastal Flood Advisory until 6 PM EDT this evening for NCZ080-
     094-194>196-199-203>205.
     Beach Hazards Statement through this evening for NCZ196-
     203>205.
MARINE...Small Craft Advisory until 2 PM EDT Saturday for AMZ150-152-
     154.
     Small Craft Advisory from 10 AM this morning to 2 PM EDT
     Saturday for AMZ156-158.

&&

$$
SYNOPSIS...MHX
NEAR TERM...CEB
SHORT TERM...MS
LONG TERM...TL
AVIATION...OJC/TL
MARINE...TL/MS
TIDES/COASTAL FLOODING...MHX