Area Forecast Discussion
Issued by NWS Newport/Morehead, NC

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FXUS62 KMHX 231804
AFDMHX

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

.SYNOPSIS...
High pressure to the north will weaken and slide offshore
today, as a strong cold front approaches from the west. The
front will move across the area Tuesday and Tuesday night. High
pressure will build over the area Wednesday through Friday.
Another cold front will approach by late next weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 1100 AM Monday...Adjusted sky cover for mostly sunny
conditions next few hours along with minor changes to hourly
temp/dew point trends. Eastern NC in warm sector between high
pressure offshore to NE and frontal zone just west of mountains.
Thicker cloudiness ahead of front will hold off until late
afternoon into evening, but enhanced CU/SCU with scattered light
shower activity offshore of Lookout to Hatteras is approaching
coast with increasing SE flow and will spread onshore through
afternoon, thus keeping lower chance POPs. Temps have warmed
quickly to 75-80 with good insolation but expected to level out
in lower 80s with increasing clouds this afternoon.

/Previous discussion/

As of 7 AM Mon...Latest sfc analysis shows 1009mb low over
western KY/TN with associated front extending from Canada down
into the Gulf Coast region...and strong 1033mb high pressure
centered over Nova Scotia extending into the SE US. High
pressure will continue to weaken and slide off the coast as
frontal system approaches from the west today. Patchy fog early
this morning inland should burn off quickly after sunrise.
Latest radar imagery shows bulk of precip well to the W/SW
extending from Indiana down into Alabama/Georgia, and scattered
showers over SC and western NC. High res guidance shows little
precip development across the area today, but could see some
isolated showers along the coast this morning and afternoon.
Precip chances increase late afternoon and early evening as
broken line of showers and storms approaches from the W/WSW,
aided by increasing dynamics with shortwave and upper trough. An
isolated storm will be possible this afternoon, though
instability, shear and moisture parameters quickly increase
after 00z. Low level thickness values and SE/S flow support
temps well above normal again today, with highs in the upper 70s
to low 80s.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
As of 315 AM Mon...Still looks active tonight, as a broken line
of showers and potentially strong to severe storms is expected
to move into the area. A deep upper trough and strong cold front
will move into the region tonight bringing periods of heavy
rain and a threat of severe storms. SPC has upgraded most of
Eastern NC into a Slight Risk of severe weather, with best
chances overnight. The main threat will be the potential for
damaging wind gusts, but cannot rule out an isolated tornado
given the low level flow and SRH increasing. 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.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 330 AM Monday...A strong cold front will bring much-needed
showers Tuesday, followed by a shot of cooler air for mid to
late week. A surface low will move up the coast by late this
weekend ahead of a strong cold front approaching from the west
by Sunday.

Tuesday and Tuesday night...Showers and possibly a few
thunderstorms will be ongoing Tuesday morning. There is the
potential for a few strong thunderstorms early in the day
Tuesday near the coast before the activity moves offshore later
in the day as mid-level trough axis swings to our north. PoPs
will be in the likely range over the eastern half of the CWA
through midday Tuesday, then along the Outer Banks into the
evening. Ahead of the front, temperatures will actually warm
quite a bit on Tuesday with mid to upper 70s across most of the
CWA.

Wednesday through Saturday...A period of pleasant weather is
expected Wednesday into the first part of the weekend. There may
a few morning showers along the Outer Banks Wednesday morning,
but those should quickly move away. Under partly to mostly clear
skies, highs Wednesday and Thursday should be in the mid to
upper 60s with lows mostly in the 40s with 50s along the coast.
Temperatures moderate by Friday back into the lower 70s with
lows in the 50s. Moisture starts to increase from the south and
southwest by Saturday as surface low starts to move north of
Florida and another strong cold front approaches from the
Tennessee Valley. Guidance holds off any precipitation until
Saturday night, so will indicate an increasing cloudiness trend
at this time.

Sunday...With deep moisture associated with surface low moving
up the coast and an approaching cold front, rain chances
increase on Sunday. The ECMWF is much more aggressive with the
low formation and the precipitation as the GFS the low further
offshore with a weaker front and less precipitation. Will hold
in the low chance range for now.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Short Term /through 18Z Tuesday/...
As of 200 PM Monday...Prevailing VFR with scattered CU and
increasing CI will continue into evening, with just a slight
chance of a shower. 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 through Friday/...
As of 345 AM Monday...Periods of lower (MVFR/IFR) ceilings may
be possible during the first half of Tuesday, especially at the
KEWN and KOAJ TAF sites as frontal system slowly crosses the
area. All of the precipitation should be east of the TAF sites
by late Tuesday with much drier conditions to prevail Wednesday
through Friday. VFR conditions should prevail Wednesday through
Friday, although some decent radiational cooling conditions
could lead to some fog, especially around KPGV and KEWN both
Wednesday and Thursday mornings.

&&

.MARINE...
Short Term /through Tonight/...
As of 1100 AM Monday...No significant changes with update. SE
winds have increasing to 10-15 KT all waters with seas 3-4 ft.
Latest guidance continues to indicate winds increasing after 4
PM and no change in SCA timing.

/Previous discussion/

As of 7 AM Mon...Latest obs show E/SE winds 5-10 kt north of
Hatteras and SE 10-15 kt with gusts to 20 kt south of
Hatteras...and seas 2-4 ft. SCA conditions expected to develop
across the southern waters and spread northward this afternoon
and tonight. SCA remains in effect for coastal waters and
sounds. High pressure extending over area from NE will continue
to weaken and slide offshore today as a cold front approaches
from the west. SE winds will continue to increase becoming 10-20
kt, with seas gradually building to 4-6 ft this afternoon and
early evening. Southerly winds peak late tonight at 20-25 kt
with gusts to 30 kt with seas 5-10 ft.

Long Term /Tuesday through Friday/...
As of 345 AM Monday...Gusty S/SSW winds are expected Tuesday
into Tuesday at 20-30 knots with seas building to as high as
10-11 feet ahead of strong cold front. Small Craft Advisories
will remain in effect for all but the inland rivers. Front
should be offshore by Wednesday morning with WNW/NW winds
subsiding to 5-15 knots. However, seas will remain elevated into
at least late Thursday over the central waters before subsiding
below SCA status. By Friday, winds should be at 10 knots or
less with seas 2-4 feet.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory from 8 PM this evening to 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 10 AM EDT Thursday for AMZ156.
     Small Craft Advisory from 7 PM this evening to noon EDT
     Thursday for AMZ150.
     Small Craft Advisory until 10 AM EDT Wednesday for AMZ158.

&&

$$
SYNOPSIS...CTC/CQD
NEAR TERM...JBM/CQD
SHORT TERM...CQD
LONG TERM...CTC/SK
AVIATION...CTC/JBM/CQD
MARINE...CTC/JBM/CQD


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