-- Discussion containing changed information from previous version are highlighted. --
730
FXUS62 KMHX 081523
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1123 AM EDT Wed May 8 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. Drier and more seasonable
temperatures expected this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
As of 1045 AM Wednesday...

Latest surface analysis shows a stationary frontal boundary
draped west to east across Tennessee, with weak lee-troughing
noted from VA south through western NC. Convection is currently
ongoing along the stationary front, and is just now approaching
the spine of the Appalachians. East of the mountains, RAP
analysis shows a modestly capped, but unstable, airmass
characterized by MLCAPE of 1000- 2000j/k and deep layer shear of
30-35kt.

Continued heating and moistening of the airmass should allow
the TN convection to continue across the mountains and into the
NC Piedmont over the next several hours. The mean steering flow
today is easterly, although radar trends suggest a bit more of
an ESE steering flow. Based on recent radar trends, the forecast
environment, and recent model guidance, the most likely
scenario is for clusters of thunderstorms to continue east into
NC through the day, with an attempt to reach the coast by this
evening. The boundary layer will be stabilizing some by this
evening, and most guidance points towards a weakening trend with
any MCS, or cluster of storms, as it reaches ENC. Given the
instability and shear forecast today, though, the weakening
trend seen in some guidance may be a bit aggressive, but still
plausible. This will be one opportunity for strong/severe
convection locally, primarily with a wind threat, and mainly
focused in the 7pm-10pm timeframe.

Another opportunity for severe weather today will be along the
seabreeze. Like yesterday, I expect the seabreeze to be pinned
close to the coast thanks to the background westerly low-level
flow. One difference today is that there should be less dry air
entrainment potential, as well as less subsidence. It appears
the primary window for this threat will be in the 3pm-7pm
timeframe. Westerly deep layer shear oriented perpendicular to
the seabreeze will favor discrete cells. If any longer-lived
storm can develop along the seabreeze, the combination of
moderate to strong instability and ~30kt of shear appears
supportive of both a wind and hail threat. A tornado threat
cannot be ruled out in this area as well, but the risk appears
low due to higher LCLs and weaker low-level shear forecast.

Finally, one last potential focus for severe weather will be
with any additional MCS that develops upstream across the TN
Valley later today. This could be a more substantial MCS that
has more potential to survive all the way to the coast, but
would be a late-night (ie. after midnight) threat, if it holds
together. This would also be primarily a wind threat, but with
some hail potential as well.

Lastly, it`s worth noting that this type of pattern generally
carries a lower confidence in convective evolution. The
environment is more than supportive of severe weather, with some
higher-end potential (ie. 60+ mph gusts and hail greater than
1"). Stay tuned for updates through the night.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/...
-- Changed Discussion --
As we get into Thurs, upper level trough over the Great Lakes
begins to pivot to the south and east while a jet streak begins
to expand over the Mid-Atlantic increasing lift. At the mid
levels a fairly potent 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 this in mind, early morning shower and
thunderstorm activity is forecast to clear out before additional
development is forecast in the afternoon with activity likely
beginning to the west and quickly moving E`wards into the FA.
Out ahead of the trough and approaching cold front the
environment across ENC appears rather supportive for severe
weather. Model soundings and latest Hi-Res guidance suggest
ample MLCAPE (1000-2000 J/kg) as well as ample DCAPE (700-900
J/kg) and inverted V soundings across the region. In addition to
this, deep layer wind shear of 30-40 kts, slightly stronger
forcing, and mid level lapse rates closer to 6.5- 7.0 C/km all
suggest we will have another threat for strong to severe
thunderstorms on Thurs afternoon and evening with storms
bringing a threat for damaging wind gusts and hail given the
environment. ENC remains in a slight risk (level 2 out of 5) for
severe weather Thurs afternoon and evening.

One potential failure mode for the Thurs threat would be what
happens with Wednesdays convective activity. While it seems to
be the outlier, some of the CAM guidance does suggest more
robust tstm activity Wed night with a MCS moving to our south
Thurs morning. If this were to occur, we could see lower
instability values and thus a potentially lower severe threat as
ENC gets robbed of more robust dynamics and moisture from the
MCS to the south. With this in mind, current thinking is this
solution has a 20% or less chance of occuring with an 80% chance
for strong to severe thunderstorm activity on Thurs and the
current forecast reflects this. Stay tuned to the forecast as we
continue to refine it on the coming updates to see how this
threat trends. Highs get into the low 90s inland and 80s across
the OBX while lows only get down into the 60s.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
As 315 AM Wed...ENC then dries out over the weekend as high
pressure ridge builds in from the west and remains over the area
into early next week. Next potential round of unsettled weather
begins to approach the area around midweek next week.

Friday through early next week... Upper level troughing finally
pivots out of the Great Lakes and overspreads the Mid-Atlantic
on Fri into Sat with the last and likely strongest mid level
shortwave rounding this troughs base on Fri. 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 then
develops along this frontal boundary on Fri as well and tracks
along or near the coast. Once again kept thunder in the grids
for Fri as HREF and NBM probs continue to highlight the
potential for about 250-500 J/kg of SBCAPE to remain over the
area. 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 as upper
level ridging begins to overspread the Southeast. Dry frontal
passage currently forecast Sun evening into Mon before surface
ridging begins to overspread ENC from the west on Mon. Temps do
cool over the weekend closer to normal.
-- End Changed Discussion --

&&

.AVIATION /16Z WEDNESDAY THROUGH SUNDAY/...
SHORT TERM /through tonight/...
As of 645 AM Wed...Pred VFR conditions expected through most of
the TAF period. Patchy fog impacting OAJ should dissipate in
the next hour or so. Scattered showers and 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 /Thursday through Sunday/...
As of 315 AM Wed...Main concern for sub-VFR conditions would be
within any shower or thunderstorm activity that impacts ENC
Thursday afternoon and evening with a slightly higher potential
for widespread sub VFR conditions on Friday as a cold front
moves through the area and more widespread shower activity is
forecast. As we get into the weekend and into early next week
VFR conditions are then forecast for the rest of the period as
high pressure ridging gradually builds in from the west.

&&

.MARINE...
SHORT TERM /through tonight/...
As of 645 AM Wed...Latest obs show SW winds 5-10 kt north of
Hatteras and 5-15 kt south of Hatteras, with seas 2-4 ft. SW
winds will be increasing through the day as the thermal gradient
strengthens. Could see a brief period of SCA conditions across
the waters and Pamlico Sound late this afternoon and evening,
with gusts to 25 kt, and seas building to 3-5 ft. Think gusty
winds will be too short lived for SCA headlines. There will be a
risk of showers and thunderstorms, especially late afternoon
through the overnight hours. Some storms may be strong to
severe.

LONG TERM /Thursday through Sunday/...
As of 315 AM Wed... Still expecting a cold front passage Fri
morning with shower and thunderstorm activity out ahead of the
front Thurs afternoon and evening. Additional shower and
thunderstorm activity possible once again on Fri across all
waters as the front pushes offshore and a weak wave of low
pressure develops along the front. Locally enhanced winds and
seas will be possible within any thunderstorm that impacts our
waters. Drier weather then expected this weekend and into early
next week.

Otherwise we start the period out under SCA conditions from
Oregon Inlet south and across the Pamlico Sound as SW`rly winds
out ahead of the cold front quickly increase after daybreak on
Thursday to 15-25 kts with gusts in excess of 25-30 kts.
Elsewhere across the northern waters and sounds as well as the
inland rivers, slightly lighter winds will persist closer to
15-20 kts with a few gusts up around 25 kts, though will have
to monitor trends in case inclusion of SCA`s becomes necessary
especially along the N`rn coastal waters and Neuse river. As the
front nears and eventually pushes offshore Fri morning SW`rly
winds then decrease down to 10-15 kts, thus ending SCA`s across
all waters. Behind the front winds gradually turn to a W and
then NW direction at 10-15 kts. By Sat light and variable winds
are forecast as high pressure ridge gradually builds in from the
west with W`rly flow at 10-15 kts returning Sun into early next
week. 3-5 ft seas along our coastal waters to start the period
quickly increase on Thurs to 5-8 ft. Seas then lower just as
quickly on Fri morning back down to 3-5 ft and then to 2-4 ft by
Fri evening remaining at these heights into early next week.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory from 10 AM Thursday to 5 AM EDT Friday
     for AMZ135.
     Small Craft Advisory from 10 AM Thursday to 8 AM EDT Friday
     for AMZ152-154.
     Small Craft Advisory from 8 AM Thursday to 8 AM EDT Friday for
     AMZ156-158.

&&

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