363
FXUS62 KMHX 260725
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
325 AM EDT Sun May 26 2024

.SYNOPSIS...
A warm front will move northeast through the area tonight. A
cold front will then move through Monday night or Tuesday.

&&

.NEAR TERM /TODAY/...
As of 215 AM Sunday...

 - Morning fog risk along the Outer Banks

 - Above normal temperatures this afternoon

 - Isolated strong to severe thunderstorm risk this afternoon

A subtle shortwave trough will move offshore early this
morning, with shortwave ridging briefly building overhead this
afternoon. At the surface, the only real feature of interest
will be the development, and inland progression, of the daily
seabreeze. Prior to the development of the seabreeze, a light
onshore flow across the Outer Banks may support a risk of low
clouds and fog, although recent obs, satellite imagery, and
webcams aren`t as supportive. For now, we`ll continue to
advertise reduced visibility and fog early this morning, but may
need to pull back on this if current trends hold.

Moving into the afternoon, the background southerly low-level
flow should encourage a more progressive seabreeze, with weaker
convergence along it. The lack of stronger convergence, plus
shortwave ridging overhead should keep afternoon seabreeze
convection at a minimum (10-20% chance). Where/if convection can
form, and be sustained, moderate instability (MLCAPE around
2000 j/kg) and 20-25kt of deep layer shear will be supportive of
a pulse severe thunderstorm risk (mainly a wind and hail risk).

With the expectation of less cloudcover, and a lower coverage
of thunderstorms, strong heating and warm low-level thicknesses
should support another afternoon of above normal temps (highs
near 90 inland, and low 80s for most beaches). The exception
will be the northern Outer Banks where highs may struggle to get
above the mid 70s thanks to the cooler onshore flow.

&&

.SHORT TERM /TONIGHT/...
As of 215 AM Sunday...

 - Watching evening/overnight thunderstorm risk

 - Near record warm lows tonight

Shortwave ridging will shift offshore tonight, allowing
southwesterly flow aloft to develop ahead of a potent upper
level trough approaching from the west. Within the developing
southwesterly flow, an impressive EML plume is forecast to
translate NE across the Southeast US. On the nose of that plume,
a few elevated thunderstorms may attempt to develop during the
evening hours across central/eastern NC. Separately, convection
is expected to be ongoing upstream from the TN/OH Valleys into
the southern Appalachians. We`ll have to keep an eye on how this
convection progresses through the night, as there is some
potential for a cluster, or two, of thunderstorms to make a run
at Eastern NC late in the evening or during the overnight hours.
There is also the potential that continued low-mid level
moistening could support scattered, elevated convection
developing that may not specifically be tied to any upstream
convection. Where/if convection can develop, the combination of
MUCAPE of 500-1000j/kg, steepening lapse rates, and modest shear
appears supportive of gusty winds and small hail. The risk of
severe weather tonight isn`t zero, but appears to be LOW (<10%
chance for the area at large). Stay tuned for updates through
the night, though, in case this risk were to increase.

Thunderstorms aside, increasing southerly flow and increasing
cloudcover is expected to support well above normal lows, with
near- record warm lows expected.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
As of 200 AM Saturday...

 - Watching thunderstorm risk Monday

 - Elevated heat risk Monday/Memorial Day

 - Not as hot mid to late-week

Synoptic Summary: On Monday, a strong shortwave will glance the
area, sending a cold front southeast through the area Monday
night or Tuesday. Guidance differ on how quickly that front will
get through Tuesday, and how far off the coast it gets.
Eventually, a potent upper level shortwave will move through
mid-week, pushing the front well offshore. A cooler post-
frontal regime then settles in to close out the work week.

Monday/Memorial Day: Continued southerly low-level flow should
support dewpoints rising into the 70s beneath steep mid-level
lapse rates. Heating of the moist boundary layer in combination
with the steep lapse rates should support moderate to regionally
strong MLCAPE of 2000+ j/kg. Temps aloft will be warming as
well, though, which will lead to a seasonably strong capping
inversion. Synoptically, an upper level shortwave will lift NE
from the Ohio Valley into the northern Mid-Atlantic, with a
glancing influence to the south across the coastal Carolinas.
The greatest chance of thunderstorms should be focused just to
our NW and N where the greatest lift is expected. If storms
manage to develop this far south, the combination of moderate to
strong instability, steep lapse rates, and sufficient deep
layer shear will be supportive of severe thunderstorms. This
will be a day to watch, especially given the above-mentioned
overlap of shear and instability, but questionable forcing and a
modest cap make confidence lower. Thunderstorms aside, and
barring more cloudcover than currently forecast, Monday has the
potential to see well above normal highs. This combined with
dewpoints in the 70s will support a "feels like" temperature of
95-100 degrees, leading to an elevated heat risk. While the heat
risk is not forecast to reach high enough to warrant heat
headlines, it`s noteworthy coming on a busy holiday weekend,
with a lot of outdoor activities, etc. The risk will be highest
for those with extended time outdoors and/or those without a way
to sufficiently cool down.

Tuesday-Wednesday: Model guidance begin to differ during this
time. The main challenge is how quickly Monday`s front moves
offshore, and whether or not it stalls for a time. The slower
guidance keeps a risk of showers and thunderstorms potentially
lasting all the way into Wednesday, while the faster and further
offshore guidance paints a much drier picture. Blended guidance
holds onto a chance of precip Tuesday, but is dry on Wednesday.
This seems reasonable for now, but be aware that the potential
exists for precip to last longer than currently advertised.
Temperatures will begin to "cool" during this time, but how cool
will depend on how quickly the front moves through.

Thursday-Saturday: There remains a fairly solid signal in
guidance depicting a potent shortwave moving through the US East
Coast, sending a strong cold front through the coastal
Carolinas Wednesday night or Thursday. It`s expected that this
will usher in a noticeably "cooler" airmass for at least a
couple of days, with dewpoints falling back into the 50s, and
lows bottoming out in the 50s and 60s. Highs are expected to be
in the 70s to near 80. While the airmass will be drying, this
may not equate to a lack of precipitation. The potential is
there for a shortwave, or two, to move through supporting at
least a low-end risk for showers and thunderstorms, especially
towards next weekend.

&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
SHORT TERM /through 06z Monday/...
As of 145 AM Sunday...

 - BR/MIFG possible overnight (40-60% chance)

 - Seabreeze TSRA possible Sunday (10-20% chance)

Clearing skies, light winds, and a moist boundary layer will
support a chance of reduced VIS overnight due to BR/MIFG. While
LIFR conditions are not off the table, guidance suggests a low
probability of this occurring across most of Eastern NC. The one
exception is along the Outer Banks where there continues to be
a fairly solid signal for LIFR conditions at times. Of note,
though, short-term guidance appears to be overly aggressive when
compared to current obs and satellite imagery in that area.
This gives me pause on whether or not widespread low CIGs/VIS
will occur there. Otherwise, away from the Outer Banks, I`ve
leaned more towards TEMPO groups for the potential sub-VFR
conditions.

Outside of the Outer Banks, any reduced VIS should quickly
improve around sunrise Sunday. During the afternoon hours, a
weak seabreeze is expected to develop and shift inland,
potentially accompanied by a low-end chance of SHRA and TSRA. To
avoid flip-flopping, I left a VCSH mention in from the previous
TAFs, but it appears the risk of SHRA or TSRA at any one TAF
site will be low (<20% chance).

LONG TERM /Monday through Thursday/...
As of 200 AM Saturday...There will be daily risk of TSRA
through Tuesday, with accompanying sub-VFR conditions. Outside
of TSRA activity, mostly VFR conditions are anticipated. On
Monday, gusty southerly winds appear likely (60-80% chance)
ahead of an approaching cold front, especially Monday afternoon
into Monday evening. SHRA/TSRA risk may linger into Wednesday
before drier air works in by Thursday.

&&

.MARINE...
SHORT TERM /through tonight/...
As of 300 AM Sunday...

 - Dense fog potential this morning

 - Great boating conditions this afternoon

Light winds of 5-10kt, and limited long-period swell, will
continue to support seas of around 1-2 ft through early this
evening, making for great boating conditions for most waters.
The one exception will be the northern rivers/sounds/coastal
waters where dense fog will impact navigation this morning. It`s
unclear how long the fog will last, and how widespread it will
be, but the latest expectation is for it to be an impact through
at least mid-morning. While the risk may not be as high as
previously thought, we`ll allow the Marine Dense Fog Advisory to
continue for now, as there are some recent indications that fog
may soon develop in this area. By tonight, a modest increase in
southerly winds should help keep the fog risk lower. This
increase will also lead to seas slowly building to 2-3 ft
through the night. For now, most waters are expected to be
thunderstorm-free through this evening. Late tonight, the risk
of thunderstorms may increase some.

LONG TERM /Monday through Thursday/...
As of 230 AM Saturday...

 - Approaching Small Craft conditions Monday/Monday night

 - Periods of thunderstorms through early next week

Several upper level waves will move through the ENC coastal waters
through early this week. Each wave will bring with it a chance
of showers and thunderstorms. A stronger wave, and associated
cold front, moves through Monday/Monday night. Southerly winds
will increase to 15-20kt ahead of this front, and may approach
25kt for some waters. Right now, though, the risk of widespread
25kt winds appears low (<10% chance). Seas of 1-3 ft over the
weekend will increase to 3-4 ft Monday with the building winds.
The highest seas are expected south of Cape Hatteras.

&&

.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Dense Fog Advisory until 10 AM EDT this morning for AMZ131-135-
     150-152-230-231.

&&

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