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402
FXUS62 KMHX 262023
AFDMHX

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

.SYNOPSIS...
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Pattern is becoming progressively more unsettled as Hurricane
Helene lifts across the eastern Gulf of Mexico and into the
southeastern CONUS. Scattered showers and thunderstorms today
with a low end risk of severe weather. Friday will bring a
slight to enhanced risk of severe thunderstorms associated with
an outer band of Helene, and then upper low pressure may bring
some occasional showers late weekend into early next week.
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&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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As of 4 PM Thursday...Synoptically we have ridging offshore and
a mid level low pressure system over the lower Midwest/Upper
Mississippi valley. These two features are advecting substantial
moisture over the Southeast, and recently upgraded Major
Hurricane Helene is expected to move along this southerly flow.
While the center of Helene will remain well to our west as it
pushes northward after landfall, the outer bands will move into
SE NC early morning Friday.

Scattered showers and thunderstorms currently located over
Duplin and Onslow counties are expected to increase in coverage
over the next couple of hours and slowly move NE. Further to the
north and east, higher subsidence aloft limits instability and
moisture, and chances of rain are less. While a waterspout
moving onshore can`t be ruled out for the Crystal Coast and
Core Banks, the threat of severe weather has decreased a bit
sine this morning`s update with meager 0-1km SRH values near 50
and 0-3km SRH values under 100 m2/s2. As we get into tonight,
coverage and intensity of showers and thunderstorms will
decrease, and we may even be completely dry between 2am-7am.
Further to our south near Cape Fear, an outer band of Helene
will be moving through in the early morning hours Friday,
bringing a threat of tornadoes with it. Through the near term we
should be free of any threats, but if this band trends faster
we could see an earlier onset of severe thunderstorms. Muggy
conditions continue tonight, with lows in the mid 70s.
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&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
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As of 4 PM Thursday...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 pseudo 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. PoPs will increase from southwest to
northeast as a more powerful band of Helene move across the
area. Tornadoes, waterspouts, heavy downpours resulting in
ponding of roads and low visibilities, and damaging wind gusts
are possible within this band, although flooding potential
remains limited as residence time of these storms over a given
location is not supportive of a flooding threat. 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. As this band moves into Duplin and Onslow counties, SRH
values do decrease a tad, and continue to lower through the
remainder of the morning into the afternoon. SPC has upgraded
southern portions of Duplin and Onslow counties to Enhanced
(3/5) with the remainder of the CWA under a slight (2/5) risk of
severe weather. 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 late afternoon for
most areas inland, and all areas including the OBX by late
evening. Rainfall totals will be 0.5-1" for much of the region
Friday, highest for SW portions and lowest for NE portions of
the CWA.

Gusty conditions will be in store tomorrow, reaching up to 30-35
mph during peak heating. High temps will be in the mid 80s and
humid conditions continue ahead of the band, but conditions will
dry up behind the band.
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&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
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As of 4 AM Thu...
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.
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&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
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SHORT TERM /through today/...
As of 230 PM Thursday...Low clouds around 3-4 kft will linger
today with scattered showers and thunderstorms possible across
southern portions of 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, although rain lets up for the
second half of the night. Shower and thunderstorm chances (some
of which could be severe) will increase Friday morning as
stronger rainbands from Hurricane Helene move across the area.
This band will quickly move NE, and after 18Z the main band of
heavy rain should be east of all TAF terminals.

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.
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&&

.MARINE...
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SHORT TERM /Through Friday/...
As of 415 PM Thursday...Marine conditions will continue to
deteriorate through the period, with wave heights currently 4-6
ft and expected to become 8-11 ft south of Hatteras and 5-9 ft
north of Hatteras by the evening Friday. Winds are currently
gusting to 10-15 mph from the SE, and will also be slowly
increasing through the period, peaking Friday morning into the
early afternoon. South/southeast gusts near 30 kts are expected
tomorrow along coastal waters south of Cape Hatteras, and
infrequent gusts of 35 kts are possible. North of Cape Hatteras,
and for inland sounds and rivers, gusts of near or just above 25
kts are possible during the morning and afternoon hours. There
will also be a band of heavy rainfall that could produce
waterspouts and damaging wind gusts Friday, moving SW to NE
through the day.


LONG TERM /Friday night 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.
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&&

.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...
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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 until 8 PM EDT this evening for NCZ196-
     203>205.
MARINE...Small Craft Advisory from 10 AM to 8 PM EDT Friday for AMZ131-
     230-231.
     Small Craft Advisory from 6 AM to 8 PM EDT Friday for AMZ135.
     Small Craft Advisory from 10 AM to 6 PM EDT Friday for AMZ136-
     137.
     Small Craft Advisory until 7 AM EDT Saturday for AMZ150.
     Small Craft Advisory until noon EDT Saturday for AMZ152-154-
     156-158.
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&&

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