Area Forecast Discussion
Issued by NWS Newport/Morehead, NC

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FXUS62 KMHX 232256

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
656 PM EDT Mon Oct 23 2017

A strong cold front will approach from the west tonight and
slowly move across the area Tuesday and Tuesday night. High
pressure will build over the area Wednesday through Friday.
Another cold front will move across over the weekend.


As of 7 pm Monday...Convection still well to the west and
southwest early this evening. Current forecast looks on track.
No changes needed. Active period will be late evening through
overnight as negatively tilted deep upper trough will move in
from W-SW accompanied by a strong surface cold front. This will
result in a high shear/low cape severe threat for area with
damaging wind gusts the main threat and an isolated tornado
possible. Instability will be limited until 11 PM-2 AM when
lingering subsidence inversion near 800 MB will be eroded, which
will coincide with increasing southerly winds and SRH.
Vorticity advection increases as models depict dampening
shortwave trough pivoting through the TN/Ohio valleys, and will
spur sfc cyclogenesis in the southern Appalachians acting to
increase dynamics and strengthening southerly flow on 40-50 kt
LLJ. Dewpoints will be quite high in the 60s and would be
sufficient for marginal instability, and the combination of
significant wind shear and marginal instability will spell a
high shear/low CAPE scenario for strong or severe storms.
Forecast soundings show MU CAPE values 500-1500 J/kg, with 0-6km
bulk shear 35-45 kt. Any heavy showers or thunderstorms could
produce strong gusty winds due to momentum transfer to the sfc
from strong winds aloft. Periods of heavy rain will also be
possible with PWAT values soaring to around 1.75". Mild
overnight with cloud cover, precip and southerly winds with lows
in the mid 60s to low 70s.


As of 330 PM Monday...Cold front near coastal in morning will be
slow to move east rest of day as it becomes parallel to upper
flow and main threat of showers/isolated tstms will be along and
east of Hwy 17. Better dynamics will be north of area, thus not
expecting any additional severe threat during the day. Drying
behind front will result in decreasing clouds western sections
in afternoon. Max temps mid 70s inland to near 80 coast.


As of 345 PM Monday...A strong cold front pushes offshore
Tuesday night with a shot of cooler air building in for mid to
late week. A surface low will move up the coast late this
weekend ahead of a strong cold front approaching from the west

Tuesday night and Wednesday...The cold front pushes offshore
Tuesday night while a longwave upper trough remains centered
west of the region with a deep moisture feed continuing along
and just off the coast. Shower chances will continue across far
eastern portions of the FA with best chances across the Pamlico
Sound and Outer Banks. An embedded shortwave trough moves
through the upper trough Wednesday finally pushing the deeper
moisture farther offshore by late in the day. Temps will be
cooler with lows Tuesday night in the lower 50s inland to around
60 coast and high Wednesday generally in the mid to upper 60s.

Wednesday night through Friday...The upper low finally exits off
the Mid Atlantic coast Wednesday night into Thursday with high
pressure building into the region bringing dry WNW flow. Temps
will be much cooler with highs in the mid 60s. High pressure
slides offshore Friday with return flow bringing gradually
warming temps with highs around 70s. Low temps fall back into
the 40s inland and low/mid 50s beaches for Thursday/Friday

Saturday through Monday...The high moves offshore next weekend
with another highly amplified upper trough digging into the
eastern CONUS and surface cold front approaching from the west
and a low pressure area lifting north along or off the
Southeast coast. Models still not in best agreement in the
details with the system but there will likely be another good
shot of precip and perhaps a period of stronger storms Sunday
as there will be increasing jet dynamics with a moisture feed
from the tropics into the region. Temps will likely be near to a
little above normal Saturday and Sunday. The system lifts north
by Monday with high building in from the west bringing a drier
and cooler airmass.


Short Term /through 18Z Tuesday/...
As of 7 pm Monday...A broken line of showers and storms is
expected to push through the terminals tonight, best chances
likely after 02/03z. Could see isolated severe storms with gusty
winds. Widespread MVFR conditions will likely develop late
tonight and early Tue morning. Showers/tstms mainly near coast
Tuesday morning with KPGV and KISO improving to VFR by 15Z. SE
to S winds will gust to around 20 KT through this evening.

Long Term /Tuesday night through Saturday/...
As of 4 PM Monday...Shower chances continue along the coast
Tuesday night and Wednesday but should be east of the TAF sites
and Pred VFR conditions expected to prevail. High pressure
builds in mid to late week with VFR conditions prevailing,
although could see patchy early morning fog, especially Friday
and Saturday mornings when radiational cooling conditions will
be maximized. High pressure weakens across the area Saturday
with the next system approaching from the west and could see
isolated showers move into the region as moist southerly flow
increases ahead of a strong cold front.


Short Term /through Tuesday/...
As of 7 pm Monday...Marine zones in good shape. No changes
needed this evening. Latest guidance in good agreement and in
line with previous forecast of increasing southerly winds
tonight persisting into Tuesday ahead of strong cold front.
Winds 20-25 kts with gusts around 30 kt expected overnight most
waters, continuing mainly outer southern and central waters
Tuesday. Seas will build to 6-8 feet by late evening and peak at
7-10 feet late Tuesday.

Long Term /Tuesday night through Saturday/...
As of 415 PM Monday...The cold front pushes through the region
Tuesday night with S/SW winds 15-25 kt during the evening,
becoming W/NW around 10-15 kt late and continuing through
Wednesday. Seas around 5-11 ft Tuesday evening gradually subside
overnight to around 4-6 ft Wednesday. Gradients tighten some
Wednesday night into Thursday and the upper trough axis swings
through and expect NW winds around 10-20 kt with seas continuing
around 4-6 ft. By late Thursday expect winds to diminish to
below 15 kt with seas dropping below SCA criteria. Light
southerly winds around 5-10 kt expected Friday with seas around
2-4 ft. High pressure centered across the region Friday into
Saturday bring light E/NE winds generally 10 kt or less with
seas continuing around 2-4 ft.


MARINE...Small Craft Advisory until 10 PM EDT Tuesday for AMZ135.
     Small Craft Advisory from 11 PM this evening to 6 PM EDT
     Tuesday for AMZ130-131.
     Small Craft Advisory until 6 PM EDT Thursday for AMZ152-154.
     Small Craft Advisory until 6 AM EDT Wednesday for AMZ156.
     Small Craft Advisory until noon EDT Thursday for AMZ150.
     Small Craft Advisory until 1 AM EDT Wednesday for AMZ158.



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