229
FXUS62 KMHX 011400
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1000 AM EDT Wed May 1 2024

.SYNOPSIS...
A weak surface trough will move through the area today. High
pressure then builds in for a couple of days before yet another
cold front impacts the area over the weekend.

&&

.NEAR TERM /Through Today/...
As of 10 AM Wed...Weak wave currently analyzed moving through
the FA this morning bringing some sct rain and clouds acrs the
region. Thinking for this afternoon is that covg will be a bit
more limited than prv thought, as 1) The current wave will be
transiting off of the coast, and 2) Less upr forcing will be
available for more robust and greater covg. Have therefore
dropped pops, esp srn half of the FA. Latest meso suite still
indicates some decent covg acrs the nern zones, where we
retained 40-50% covg, but removed any likely pops out of the
fcst. Severe threat should be limited, but cannot rule out a
stronger storm or two producing some 40-60 mph gusts, as
previously mentioned.

Prev disc...As of 645 AM Wednesday...

A weak upper level low is moving slowly east this morning, and
has just now reached far western sections of ENC. Modest
moisture advection and lift associated with the wave is
combining with a modestly unstable airmass, supporting the
ongoing shower and thunderstorm activity across southwestern
sections of ENC. Short- term guidance has been struggling with
the ongoing convection, with most of the guidance insisting the
storms will weaken over the next hour or so. This hasn`t been
the case, and it`s unclear how long the morning convection will
last. Because the convection appears tied to the upper level
wave, itself, and with the plume of instability extending east
across much of ENC, it stands to reason that this activity will
continue east through the morning. With daytime heating,
instability will steadily build ahead of the wave, and there is
the potential for the convection to strengthen some as it moves
east. For now, though, a lack of stronger instability, plus very
weak shear, is expected to keep the risk of strong/severe
storms very low (<5% chance) this morning.

By this afternoon, modest moisture advection ahead of a
southeastward-moving weak front should allow dewpoints to rise
into the mid 60s. Heating of the moist boundary layer should
support moderate instability, on the order of ~1000 j/kg SBCAPE.
Early in the afternoon, deep layer shear is forecast to be weak
(~20kt). However, by mid to late afternoon, the flow aloft will
become northwesterly atop a southerly SFC wind as the above-
mentioned upper wave shifts further east. This will give a
little curvature to the hodograph, and will lead to a modest
increase in deep layer, directional shear to around 25-30kt. At
face value, this type of environment is generally supportive of
multicell clusters capable of gusty winds of 30-40 mph. The
severe weather threat in an environment like this is low (<10%
chance), but isn`t zero. I suspect the "best" chance of seeing a
marginally severe thunderstorm would be during the mid to late-
afternoon period as the deep layer shear increases.

A couple of caveats with the thunderstorm coverage and
intensity today. 1) Questionable forcing. Low-level convergence
with the above- mentioned cold front is forecast to weaken with
time as it approaches the coastal plain. Meanwhile, a seabreeze
is expected to develop, and this may end up being the best focus
of low-level convergence. Between the weakening front, the
seabreeze, and some weak support with the upper level shortwave,
there still appears to be a decent signal for scattered
thunderstorms focused in the 12pm- 7pm timeframe. I didn`t stray
too far from the previous forecast regarding coverage today,
but it should be noted that the lack of stronger forcing shows
up in some short-term guidance with a lower coverage. I suspect
the seabreeze will be the primary driver of convection this
afternoon, with the surface front adding some support. The lack
of stronger forcing should also help to keep the severe weather
risk at bay as this will tend to lower the risk of deeper, more
sustained, updrafts. 2) Morning convection. It`s unclear what,
if any, impact the morning convection will have on the
coverage/intensity this afternoon. There isn`t any source of dry
air to scour out the low-level moisture, so it shouldn`t take
much heating to realize the modest instability forecast. For
now, I`ll leave the afternoon forecast as-is, but it`s possible
the morning convection will limit how much convection occurs
this afternoon.

&&

.SHORT TERM /Tonight/...
As of 200 AM Wednesday...

Thunderstorm activity should be diurnally-driven, with a
downward trend in coverage and intensity after 7pm this evening.
In the wake of the thunderstorms, winds will be very light, or
even calm, and skies will attempt to clear out. This plus
whatever rain falls today should support an increased fog
potential tonight. There is some uncertainty with how much
clearing will occur, but the pattern, plus model guidance,
supports a risk of dense fog.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As of 4 AM Wednesday...

KEY MESSAGES

- Quiet until this weekend when conditions become more unsettled
  through early next week

- Best rain chances on Sunday

FORECAST DETAILS

Thursday...A ridge building overhead will send temps well into the
80s across the coastal plain while the beaches hang back in the low
70s. The afternoon seabreeze could support the development of a few
showers as it moves inland.

Friday...A passing shortwave embedded within the ridge will cause a
slight bump in winds and an increase in cloud cover. Additionally, a
dry cold front to our north will dip south into our northern
counties. Temps will reach their warmest marks of the week before
the cold front moves through with the coastal plain topping out in
the upper 80s and the beaches in the mid 70s.

Saturday-Tuesday...The mid-level ridge remains over the eastern US
Saturday but weakens as a complex series of shortwave troughs and
surface lows move toward the area, resulting in unsettled conditions
that will persist into the beginning of next week. Chances for
showers and storms start to increase Saturday morning and peak
Sunday (30-50%). Shower and storm chances hang around through the
period due to the lingering nature the front, but they will be
decreasing as we progress into next week (25-30% Monday, 15-20%
Tuesday). Saturday`s high temps will be a few degrees cooler than
Friday due to the dry cold front that will dip south (low 80s
coastal plain, low 70s beaches). Temps remain around the same Sunday
before rebounding next week with highs expected to reach back
into the mid to upper 80s across the coastal plain Tuesday.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM /through 12z Thursday/...
As of 645 AM Wednesday...

KEY MESSAGES

- Increased TSRA risk today

- BR/FG likely tonight (60-80% chance), with IFR, or lower,
  conditions possible (30-50% chance)

FORECAST DETAILS

SHRA and TSRA activity has been more widespread this morning
than originally forecast, and the TAFs have been updated to
reflect this trend. The ongoing activity will likely continue
slowly east, eventually impacting PGV and EWN. It looks like the
greatest TSRA risk this morning will be from OAJ to EWN. It`s
unclear what impact the morning TSRA will have on the afternoon
TSRA potential, but for now, I`ll leave the forecast as-is, and
continue with a TSRA mention in the TAFs, focused in the 18-23z
timeframe. Occasional low CIGs/VIS will accompany the SHRA and
TSRA, with sub-VFR conditions expected at times. Once the TSRA
move dissipate this evening, clearing skies and light winds are
expected to lead to an increased risk of BR/FG. The potential is
there for IFR/LIFR conditions to occur.

LONG TERM /Thursday through Sunday/...
As of 4 AM Wednesday...Pred VFR expected through Friday.
Conditions become more unsettled this weekend through early next
week due to a series of disturbances moving across the area.
There will be multiple chances for showers and storms with
Sunday having the greatest threat (30-60%). Periods of lower
CIGs and VIS as well as gusty winds if near any storms can be
expected.

&&

.MARINE...
SHORT TERM /through tonight/...
As of 200 AM Wednesday...

A weak cold front will move slowly southeast across the ENC
waters late this afternoon through tonight. Because of the weak
nature of the front, I do not expect a significant northerly
wind surge to develop. In fact, a weakening gradient around the
front is expected to keep winds light (5-15kt) for most of the
day and into tonight. Seas of 3-4 ft are forecast to slowly lay
down through tonight. However, the ongoing long-period ENE swell
of 3-4 ft at 12-13s hasn`t been modeled as well, and seas may
not lay down as quick as forecast.

Scattered showers and thunderstorms will impact the central and
southern waters this morning, associated with an upper level
wave approaching from the west. During the afternoon hours, the
thunderstorm threat will shift inland with the seabreeze, mainly
impacting inland rivers and sounds. Some of those thunderstorms
may work back towards the coastal waters this evening, but
confidence in this is low. Once the thunderstorms dissipate,
there will be an increased risk of fog. The potential exists for
a period of sub 1SM visibilities during this time, and we`ll
monitor this in later forecasts in case a Marine Dense Fog
Advisory is needed.

LONG TERM /Thursday through Sunday/...
As of 4 AM Wednesday...

KEY MESSAGES

- Sub-SCA conditions with multiple chances for showers and
  thunderstorms

FORECAST DETAILS

Sub-SCA conditions are expected through the period but multiple
chances for showers and thunderstorms could create hazardous
boating conditions. Sunday presents the best opportunity for
showers and storms (30-40%). Winds will be 5-10 kt out of the
NE on Thursday but will veer to the southwest by early Friday. A
dry cold front will sag south into northern counties on Friday.
North of Cape Hatteras, 5-10 kt winds will be out of the E by
the afternoon. South of Cape Hatteras, winds will be 5-10 kt out
of the ESE. Winds and seas pick up Saturday-Sunday as a front
approaches. Winds will be ESE around 10-15 kt Saturday and then
southerly by Sunday. Seas remain around 2 ft until Saturday when
they will increase to 2-4 ft.

&&

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

&&

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