836
FXUS62 KMHX 172339
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
739 PM EDT Fri May 17 2024

.SYNOPSIS...
A frontal boundary will stall across the waters today, then
shift east tonight as another area of low pressure approaches
from the west. That low will impact the area through early next
week.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 7:30 PM Friday...Latest surface analysis shows a
stationary boundary draped roughly along HWY17. This boundary
has supported a couple of training showers for the past few
hours but coverage is expected to expand this evening as the
boundary lifts north as a warm front. The forecast remains on
track with no notable changes made with the evening update.

Previous Discussion...17z/1pm surface analysis reveals a weak
area of low pressure over central NC, with a subtle confluence
zone/surface boundary stretching southeast from the low to the
Crystal Coast. The combination of this boundary, the seabreeze,
and the exit region of an approaching upper jet will continue to
favor isolated to widely scattered showers and thunderstorms
through at least early this evening. Deep layer shear will
increase to 30-40kt through the afternoon, but instability will
remain on the lower side (MLCAPE ~500j/kg). This
shear/instability combo isn`t overly supportive of severe
weather, but if any taller, more sustained core can develop,
there would be a risk of gusty winds of 30-50 mph. For the area
at large, the risk of severe weather appears to be LOW (<5%
chance) through this evening.

Later this evening through tonight, a modest southwesterly LLJ
is forecast to develop across the Carolinas, which should
encourage the above-mentioned surface boundary to begin lifting
north as a warm front. Some guidance also suggests a weak low
may develop along the northward-moving boundary. Generally-
speaking, this will lead to increased low-level forcing through
the night. Additionally, a broad area of WAA and upper level
diffluence will add some large-scale forcing for ascent.
Increased lift plus increasing low-mid level moisture advection
is expected to favor an increasing risk of showers and
thunderstorms, especially after midnight.

Elevated instability will increase to 250-500j/kg MUCAPE, which
may support a few stronger elevated cores, but overall, the
risk of severe weather continues to look LOW (<5% chance)
tonight. The deeper convection is expected to remain offshore
through the night. Given the WAA pattern, temps will probably
hold steady, or slowly rise, through the night.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
As of 145 PM Friday...

- Multiple rounds of thunderstorms expected on Saturday, some
  of which could be strong to severe

Synoptically, a warm front is forecast to lift north through
ENC during the day, eventually stalling west to east across
northern sections of ENC by the afternoon hours. Low pressure is
then forecast to develop along the boundary, shifting southeast
and offshore Saturday night. Aloft, a modest upper level jet is
forecast to overspread the coastal Carolinas through the day
and into the night.

While short-term guidance still differ on the convective
evolution, there appears to be a general trend towards multiple
rounds of convection Saturday into Saturday evening, with at
least some risk of severe weather.

An initial round of thunderstorms is expected along the
northward- moving warm front. Elevated instability increasing to
around 500j/kg, plus effective shear of ~40kt may support a few
stronger cores with some hail potential. However, it appears
the severe weather risk will remain LOW (10-20% chance) for the
area at large with this initial activity. If elevated
instability ends up higher, the risk of hail and gusty winds
would also increase.

Confidence then begins to lower as we move into the afternoon
and evening hours. If sufficient breaks in the clouds can occur
after the morning convection, and/or if sufficient low-mid level
moistening occurs, there should be time for the airmass to
recover ahead of the surface low forecast to develop along the
west/east frontal boundary. During this time, the potential
exists for moderate destabilization to occur along and south of
the boundary, with MLCAPE topping out as high as 1000+ j/kg.
Additionally, deep layer shear of 40kt+ will be more than
supportive of organized convection, including severe weather.

The forecast challenge, then, is will the airmass recover, and
where will the greatest lift, and risk of severe weather, be
focused. In general, I expect convection to redevelop, or
strengthen, along the west/east boundary, with a tendency to
shift back southeast towards the coast during the evening hours.
The synoptic pattern favors mostly a damaging wind and large
hail risk during the afternoon and evening hours. However, right
along the above-mentioned boundary, there could be a
conditional tornado risk that materializes. Additionally, there
will also be a concern for heavy rain/flash flooding if
convection trains along the stalled frontal boundary, especially
with a deep layer of moisture present, and storm motions
parallel to the boundary. SPC has the southern half of our area
in a Slight Risk of severe weather, which nicely matches with
where I expect the above-mentioned boundary, and best overlap of
shear/ instability, to reside.

Temperatures on Saturday will vary quite a bit from SW to NE.
South of the stalled front, highs should warm into the 70s and
80s, while north of the boundary, highs may struggle to get out
of the 60s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
As of 400 AM Friday...A complex low pressure system will impact
the region through the weekend. High pressure builds in from
the north for the first half of the workweek. A cold front will
approach from the west toward the latter half of the week.

Sunday through Sunday night...A complex low pressure system
will impact the region through the weekend. The low will push
offshore Saturday night with northerly flow ensuing as high
pressure begins to ridge southward across the Mid-Atlantic
bringing a more stable environment across the area, however the
upper trough will slowly push across the area Sunday continuing
to bring showers across the region.

Monday through Thursday...The upper low slowly slides southward
early next week with high pressure building across the Mid-
Atlantic. There could be a few lingering showers early next
week, especially along the coast, but otherwise expect dry
conditions through Wednesday. Guidance is a bit slower with a
mid level shortwave and attendant cold front approaching the
area which now looks to move across the area late Thursday, but
moisture continues to appear limited with deep layer westerly
flow providing subsidence to the lee of the Appalachians.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
SHORT TERM /through 18z Saturday/...
As of 7:30 PM Friday...Shower and thunderstorm coverage will
increase as we head into the overnight hours. Ceilings will
lower as moisture and precip chances increase, with low-end MVFR
CIGs expected for all TAF sites before sunrise. Shower and
thunderstorm chances continue through the period with the
greatest chance of thunder being tomorrow afternoon and evening.
Reduced VIS, as well as gusty winds exceeding 50 kt and small
hail, are possible where thunderstorms occur.

LONG TERM /Saturday night through Wednesday/...
As of 430 AM Friday...A low pressure system will impact the
area through the weekend bringing periods of sub-VFR conditions
 through Sunday. Pred VFR conditions are expected Monday into
Tuesday.

&&

.MARINE...
SHORT TERM /through Saturday night/...
As of 145 PM Friday...

A stalled front bisects the ENC coastal waters at this time,
separating 10-15kt north winds from 5-15kt E or SE winds to the
west of the boundary. This boundary is currently located around
the western Pamlico Sound/Cape Lookout vicinity. Showers and a
few thunderstorms near this boundary will impact the Pamlico and
Neuse Rivers, as well as the western Pamlico Sound through
sunset.

The boundary then lifts north later tonight and Saturday, with
winds becoming E or SE for all waters. Wind speeds will be in
the 5-15kt range. Along the boundary, widespread showers and
scattered thunderstorms are expected, the strongest of which
could produce gusty winds of 34kt+ and small hail. The boundary
then stalls, with breezy southwesterly winds of 10-20kt
developing south of it, and 10- 20kt easterly winds to the
north. A low will move along the boundary, then shift offshore
Saturday night. Increasing northeasterly winds are then expected
behind the departing low. Winds will be approaching 25kt late
Saturday night, but the better chance of 25kt+ winds looks to
hold off until Sunday.

For the coastal waters, seas of 3-5 ft will be common through
Saturday. Seas will then begin to build to 4-6 ft Saturday night
within the strengthening northeasterly surge of wind behind the
departing low.

LONG TERM /Sunday through Wednesday/...
As of 445 AM Friday...A complex low pressure system will impact
the region through Sunday bringing unsettled weather through
the period. The best opportunity for SCA conditions will
develop Sunday and continue through Monday with N to NE winds
around 20-25 kt and seas building to 5-8 ft as low pressure
deepens as it pulls offshore. Conditions gradually improve
Monday night into Tuesday with seas expected to drop below 6 ft
during the day Tuesday. There are differences among the models
the timing and track of this system, so be sure to follow
updates as details come into focus.

&&

.HYDROLOGY...
As of 145 PM Friday...

Briefly intense rainfall rates will occur with showers and
thunderstorms this afternoon, but the risk of flooding appears
LOW (<5% chance for the area at large). Late tonight into
Saturday night, there is the potential for multiple round of
thunderstorms, with an area average of 0.75"-1.50" of rain.
However, it appears likely that a front will stall west to east
for a time on Saturday, with the potential for convection to
train along the boundary. If this occurs, max QPF guidance
suggests rainfall amounts as high as 3- 6". This may occur over
a relatively small area, but is noteworthy coming on the heels
of the recent round of rain. Where/if this occurs, there would
be a locally higher risk of hydro/flash flooding concerns, and
we`ll be closely monitoring this potential.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...None.

&&

$$
SYNOPSIS...MHX
NEAR TERM...RM/OJC
SHORT TERM...RM
LONG TERM...SK
AVIATION...OJC/SK
MARINE...RM/SK
HYDROLOGY...MHX