213
FXUS62 KMHX 261132
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
732 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.
Friday will bring unsettled weather as some impacts from Helene
are felt, and then upper low pressure may bring some occasional
showers late weekend into early next week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 3:30 AM Thursday...The upper level ridge will remain anchored
off the east coast today. The upper trough will continue to dig
further into the Mississippi River Valley and has become cut off
while Hurricane Helene is intensifying as it approaches the The Big
Bend of Florida. Widely scattered showers and isolated thunderstorms
will overspread ENC today, but our proximity to the offshore upper
ridge will provide some mid-level subsidence, which may minimize
deeper convection along the northern tier of the FA.

With bands of convection moving onshore, severe storms will be a
possibility throughout the day, especially south of Highway 70. SPC
has outlined the southern half of the CWA in a Marginal Risk (Level
1/5) for the potential of damaging wind gusts and an isolated
tornado. With the outer bands of Helene pumping ample moisture into
the Carolinas (2-2.5 PWATs), some heavier showers can be expected,
and any training cells could produce localized flooding issues. Warm
SSTs, strong deep layer shear, and marginal instability (MLCAPE 500-
1000 J/kg) could support the formation of waterspouts. The Crystal
Coast will need to be watched the closest for this activity.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
As of 3:30 AM Thursday...The concern for severe hazards increases as
we move into the overnight hours. PoPs will increase from southwest
to northeast after midnight as more powerful bands of Helene move
across the area. The late overnight/early Friday morning hours will
host a heightened threat for heavy rainfall, tornadoes, waterspouts,
and damaging wind gusts. Again, any training cells could produce
localized flooding issues.

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
As of 4 AM Thu...

Friday...The main item of interest will be the impacts from TC
Helene. The center of the storm will be moving through GA and
then into the TN Valley Friday morning. With the large size of
the system, and psudo warm front moving through the ctrl/ern
Carolinas, a heavy rain band or two will be propagating through
ENC during the day. 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. SFC
based CAPEs 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 significant low lvl helicity values (300-400
M2/S2), and a favorable environment for a couple tornadoes will
be in place, as indicated by large hodograph structures acrs
ENC. SPC has upgraded the marginal risk that was in place to a
slight risk. Concerning heavy rain threat, 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 by mid to late
afternoon for most areas inland, and all areas including the OBX
by early evening. 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 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 well into the mid to
perhaps a few upper 80s. Heat indices will be in the low 90s.

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 to around 70 for lows.

Wednesday...The upper low should finally exit the region and
offshore by mid week, with broad nwrly flow ensuing and bringing
drier and cooler air back to the region. Temps should drop back
down to around climo with highs in the 75-80 range for most, and
lows upper 50s to low 60s.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
SHORT TERM /through today/...
As of 7:30 AM Thursday...Low clouds around 3-4 kft will linger
today with scattered showers and thunderstorms possible across
the FA, which could introduce brief interruptions to otherwise
low-end VFR conditions. As we get into the evening and overnight
hours, the signal for sub-VFR flight cats becomes much greater.
Shower and thunderstorm chances will increase late tonight/early
Friday morning and will be accompanied by gusty winds (15-20
kt) as stronger rainbands from Hurricane Helene move across the
area. Some storms may be strong to severe.

LONG TERM /Fri through Mon/...
As of 4 AM Thu...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, TS, and sub- VFR conditions during
the day Friday. VFR returns by evening as drier air moves in
behind the system. Sat should remain dry, though ocnl showers
will be possible Sun through early in the week as upr low
pressure will migrate through the region.

&&

.MARINE...
SHORT TERM /Through tonight/...
As of 3:30 AM Thursday...Marine conditions will deteriorate
through the period. The wind field will stay generally
southeasterly but will increase from south to north through the
day. The coastal waters south of Cape Hatteras are currently
10-15 kt and will increase to 20-25 kt with gusts to 30+ kt by
tonight. The coastal waters north of Cape Hatteras will increase
from 10 kt to 15-20 kt with gusts to 25 kt. Seas south of
Oregon Inlet are currently 5-6 ft at 11-13 seconds and will
increase to 7-9 ft by late tonight. Seas off the NOBX will
remain around 5-6 ft through the period. Given these
conditions, SCAs are in effect for all coastal waters through
the period.

LONG TERM /Fri through Mon/...
As of 4 AM Thu...On Fri, gradient inc to 20-25 kt sustained and
gusts to 30 kt for the coastal waters and seas build to 7-10 ft
with the sserly winds. A few gusts to 34 kt possible briefly for
the ctrl/srn waters south of Hatteras during the day Fri. Winds
quickly diminish Fri night, though high seas will be slow to
respond and remain above 6 ft into Sat. Sun into early next week
will bring lighter winds of 5-15 kt and seas of 2-4 ft.

&&

.TIDES/COASTAL FLOODING...
As of 4 AM Thu...The coastal flood threat continues for all of
coastal North Carolina through today 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 coastal impacts could be felt across a portion of
ENC on Fri into Fri evening thanks to southerly onshore winds
and large waves, and coastal flood advisories will likely have
to be continued for mainly oceanside zones from Hatteras Island
southward.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Coastal Flood Advisory until 6 PM EDT this evening for NCZ080-
     094-194>196-199-203>205.
     High Surf Advisory from 3 AM Friday to 4 AM EDT Saturday for
     NCZ195-196-199-204-205.
     Beach Hazards Statement through this evening for NCZ196-
     203>205.
MARINE...Small Craft Advisory from 10 AM to 6 PM EDT Friday for AMZ131-
     136-137-230-231.
     Small Craft Advisory from 6 AM to 6 PM EDT Friday for AMZ135.
     Small Craft Advisory until 7 AM EDT Saturday for AMZ150.
     Small Craft Advisory until noon EDT Saturday for AMZ152-154-
     156-158.

&&

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