846
FXUS62 KMHX 080043
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
843 PM EDT Tue May 7 2024

.SYNOPSIS...
High pressure will continue to strengthen offshore while weak
troughing continues for the next few days, as warm moist
southerly flow leads to unsettled conditions. A strong frontal
system will move through Friday.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 830 PM Tuesday...Scattered convection that developed
across ENC this afternoon has dissipated/moved offshore. A few
storms continue upstream but expect them to weaken as they push
toward the area. Cannot rule out a stray shower this evening but
expect mainly dry conditions through the rest of the overnight
as shortwave ridging builds aloft. Mild temps overnight with
lows generally in the upper 60s.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
As of 145 PM Tuesday...

Mid-upper level ridging will shift offshore on Wednesday,
allowing more of a zonal flow aloft to develop from the TN
Valley east through the Carolinas. Within this flow, an impulse,
or two, lifting out of the Lower MS Valley will traverse the
Appalachians and Carolinas later Wednesday through Wednesday
night, interacting with a moist and unstable airmass to support
an increased risk of clusters of thunderstorms in a broad zone
from the TN Valley to the Carolinas. Locally, there will also be
some potential for convection along the seabreeze (which will
tend to be pinned closer to the coast thanks to the westerly
low-level flow forecast).

This type of setup is a classic one for MCS development, and I
expect a MCS, or two, to impact portions of the Carolinas
Wednesday/Wednesday night. This type of pattern can also be a
low confidence one, though, as models can sometimes struggle
with the evolution of convection as it moves downstream. This is
a pattern, though, that can support a longer-lived MCS running
the length of NC. And, locally, there is also the potential for
seabreeze convection unrelated to any MCS`, especially with less
ridging/subsidence compared to today. With all of the above in
mind, I have opted to go with a broad-brushed 30-40% chance of
thunderstorms for the entire Wednesday/Wednesday night period.
We`ll continue to refine when/where the best chance will be in
the coming shifts.

From a hazards standpoint, any MCS that develops will carry a
risk of damaging winds. Mid-level lapse rates are forecast to be
steeper than today (as high as 6.5-7.0 C/km), so hail will be a
concern both with linear segments and with any discrete storms
that manage to develop on the seabreeze. It`s also worth
pointing out that forecast MLCAPE of 2000-3000j/kg and deep
layer shear of 25-30kt will be supportive of instances of
higher-end severe weather for this area (ie. 60+ mph winds and
>1" size hail). The caveat is that the evolution of upstream
convection will have a significant impact on our airmass, as any
early convection would tend to keep instability lower, and
vice-versa. SPC has recently upgraded a portion of our area to a
"Slight" risk of severe weather, which appears warranted given
all of the factors outlined above.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
As 330 AM Mon...There have been a few changes in the forecast
since the previous update but the overall trend remains the same
as ENC will remain unsettled into this weekend with a daily
chance for showers and thunderstorms into Friday before
potentially drying out on Sat. Highest risk for severe weather
still looks to be on Thursday. High pressure ridging finally
overspreads ENC early next week.

Thursday...Have made some tweaks to the forecast for Thurs
with the latest data and trends in mind. Upper level zonal flow
begins to overspread ENC on Wed out ahead of a positively tilted
upper trough which will be located in the Upper Midwest to
start the period. Within this zonal flow, guidance has come into
better agreement that a weak mid level disturbance will trek
across the Carolinas and then offshore Wed evening into Thurs
morning.

As Wednesday`s shortwave pushes off the coast, any leftover
shower and thunderstorm activity will quickly weaken Wed night
into Thurs and push offshore. As we get into Thurs, upper level
trough migrates over to the Great Lakes region while a jet
streak begins to expand over the Mid-Atlantic increasing lift.
At the mid levels a second and stronger mid level shortwave
rounds the base of the trough and tracks over the Mid-Atlantic
Thurs afternoon/evening while at the surface deepening low
pressure system in the Great Lakes tracks NE`wards into the
Northeast with its associated cold front nearing western NC and
a prefrontal trough setting up over the Coastal Plain Thurs
evening. With ample MLCAPE 1000-2000 J/kg over ENC in the
afternoon, stronger wind shear 30-40 kts, and slightly stronger
forcing, ENC will once again have another threat for scattered
showers and isolated to widely scattered strong to severe tstms.
Once again the main hazard within the strongest storms will be
damaging winds and hail. Given the higher risk for severe wx on
Thurs ENC is in a slight risk (level 2 out of 5) for severe
weather Thurs afternoon and evening. Highs each day get into the
low 90s inland and 80s across the OBX while lows only get down
into the 60s.

Friday through early next week... Upper level troughing finally
pivots out of the Great Lakes and overspread the Mid-Atlantic
on Fri into Sat with the last and likely strongest mid level
shortwave rounding this troughs base on Fri. This is where the
biggest change in the forecast has been as at the surface, low
pressure in the Northeast will continue to trek NE`wards while
its associated cold front finally tracks across the region
slowing as it pushes offshore. A wave of low pressure develops
along this frontal boundary on Fri as well and tracks along or
near the coast. The eventual track will have a major impact on
whether the area sees thunder on Fri as a low track just
offshore keeps us on the cool and more stable side while a low
track just inland gives us a threat for additional
thunderstorms on Fri. For now kept thunder in the grids for Fri
afternoon and evening until we get more clarity on the eventual
evolution of the forecast. Either way Friday looks to have the
best shot at widespread precip. Through the weekend and into
next week general troughing remains over the Eastern Seaboard
before gradually ejecting out into the Canadian Maritimes. Will
have one more chance at a frontal passage Sun evening into Mon
before surface ridging begins to overspread ENC from the west.
Temps do cool over the weekend closer to normal.

&&

.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM /through Wednesday/...
As of 8 PM Tuesday...Pred VFR conditions expected through most
of the TAF period. HREF probs for stratus overnight is less than
10%. Scattered thunderstorms expected to develop late in the
afternoon, mainly after 20z which may bring occasional sub-VFR
conditions along with the potential to bring strong wind gusts
and hail.

LONG TERM /Wednesday night through Sunday/...
As of 330 AM Tue... Expecting primarily VFR conditions outside
of any shower and tstm activity Wed night and Thurs with the
best shot at seeing widespread sub-VFR conditions on Fri. VFR
conditions then return on Sat across the CWA.

&&

.MARINE...
SHORT TERM /through Wednesday night/...
As of 830 PM Tuesday...Winds have not strengthened as much as
expected early this evening and have trimmed the SCA back to
south of Ocracoke Inlet where they are currently the strongest
with gusts approaching 25 kt.

Previous discussion...Breezy southwesterly winds of 10-20kt
will continue through tonight. The potential still exists for a
period of 25kt winds associated with the strengthening thermal
gradient. However, winds haven`t responded as much as I thought
they would, which lends itself to lower confidence through the
evening regarding the Small Craft Advisory. Buoys south of Cape
Lookout are getting close to 25kt, and given what happened
yesterday, plus the overall environment not changing much, I`ll
keep the SCA going to account for the potential. Through this
evening, scattered showers and isolated thunderstorms will be
possible (20-40% chance), with the risk shifting beyond 20nm
after sunset.

Wednesday is looking similar to today, with southwesterly winds
increasing through the day as the thermal gradient strengthens.
Wednesday`s gradient is expected to be stronger than today`s,
and another round of SCA conditions appears likely (50-70%
chance). We`ll let the current SCA run through tonight, then
consider hoisting another advisory for later tomorrow through
tomorrow night. Once again, there will be a risk of showers and
thunderstorms, especially mid-afternoon through the overnight
hours. Through Wednesday night, seas of 3-5 ft will be common,
with 5-6 footers possible.

LONG TERM /Thursday through Sunday/...
As of 340 AM Mon...Not much change in the forecast overall as
unsettled weather will remain in place into the end of the week
promoting a daily chance at showers and thunderstorms across our
waters each day. Locally enhanced winds and seas will be
possible within any thunderstorm that makes its way into the
area. Otherwise the background winds remain SW`rly at 10-20 kts
on Wed with a few gusts up near 25 kts at times Wed aftn and
evening as the thermal gradient sets up. As we get into
Thursday, gradient tightens out ahead of an approaching cold
front allowing winds to increase closer to 15-25 kts with gusts
in excess of 20-30 kts across our waters. Strongest winds will
be located across our coastal waters and larger sounds likely
necessitating a SCA for Thurs across portions of ENC. As the
front nears and begins to push offshore on Fri winds decrease
closer to 10-15 kts and become more W`rly on Fri before becoming
NW`rly and increasing slightly to 15-20 kts Fri night behind
the frontal passage. NW`rly winds continue through Sat before
winds return to a S`rly direction towards the end of the
weekend. 3-5 ft seas along our coastal waters on Wed increase to
4-7 ft on Thurs as the winds increase with some 8 ft seas
possible along the Gulf Stream waters. Seas gradually ease over
the weekend as winds ease down to 2-4 ft.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory until 8 AM EDT Wednesday for AMZ156-158.

&&

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