326
FXUS62 KMHX 300837
AFDMHX

Area Forecast Discussion
National Weather Service Newport/Morehead City NC
437 AM EDT Tue Apr 30 2024

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

&&

.NEAR TERM /TODAY/...
As of 200 AM Tuesday...

Mid/upper level ridging will shift offshore today as a
shortwave shifts east out of the TN Valley. Despite continued
low-level moisture advection, the combination of residual
subsidence and warm temps aloft are expected to keep the risk of
showers at a minimum again today as the seabreeze moves inland.
Yesterday the chance of showers was close to zero. Today it
will be about 5-10%. Once again, temperatures this afternoon
will top out in the mid 80s inland(~10 degrees above normal),
and the 70s along the coast (close to normal).

&&

.SHORT TERM /TONIGHT/...
As of 200 AM Tuesday...

SFC low pressure is forecast to pass south of Southern New
England tonight, with an associated weak frontal boundary moving
slowly east from the Appalachians to the Carolinas and
Virginia. A modest LLJ is forecast to develop ahead of the
advancing front, with steady low- mid level moistening expected
through the night. Mid-level lapse rates will be weakening with
time, but a deepening layer of moisture appears supportive of a
zone of weak instability (250-500j/kg MUCAPE) developing ahead
of the front and an upper level shortwave approaching from the
west. Large-scale forcing for ascent is forecast to be on the
weak side, but a weak coastal trough moving inland plus modest
low-mid level convergence appears supportive of scattered
showers and thunderstorms developing from coastal SC northeast
through SE NC after midnight. Weak effective shear (~20kt) and
weak instability is expected to limit any severe weather
potential tonight. Where thunderstorms manage to develop,
rainfall amounts as high as 0.25-0.50" will be possible.
Otherwise, amounts are forecast to be less than 0.10".

With increasing clouds, and steady boundary layer moistening,
temperatures tonight are expected to be very mild for late
April, only dropping into the mid 60s. For perspective, normal
lows this time of year are in the mid to upper 50s.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
As of 330 AM Tuesday...

KEY MESSAGES

- Inland highs in the low to mid 80s for the rest of the week

- Best rain chances Wednesday and then an unsettled weekend and
  start to the new week

FORECAST DETAILS

A shortwave trough will move east across the area on Wednesday
and support shower and thunderstorm chances (30-60%). As for
severe potential, the threat appears low but non-zero with the
high CAPE/low shear environment being painted by the CAMs. Highs
will reach the low 80s with dew points in the low 60s, which
will generate plenty of instability to support thunderstorms. The
CAMs are showing large MUCAPE of 1500-2000 j/kg but weak
effective shear. However, it should be noted that the CAMs are
showing a higher amount of shear than they were 24 hours ago.
This is especially true along counties south of HWY 70 near the
coast, so this will be a trend to keep an eye on.

We return to warm, dry weather on Thursday and Friday with a
ridge building over the southeast US. Highs will be in the mid
80s across the coastal plain and low 70s at the beaches.

Unsettled weather returns this weekend with multiple chances for
showers and thunderstorms. Surface high pressure will be
gradually washed out as a surface low forms due to a shortwave
trough moving across the southeast. At the same time, a cold
front associated with a deep low over south-central Canada will
move into our area and stall. PoPs increase west to east on
Saturday with shower and thunderstorm activity possible through
Monday (15-30% chance).

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
SHORT TERM /through 06z Wednesday/...

As of 145 AM Tuesday...

KEY MESSAGES

- Sub VFR conditions possible overnight (30-50% chance)

FORECAST DETAILS

The main forecast challenge over the next 6-8 hours will be the
potential for BR/FG/low stratus. With high pressure offshore to
the southeast of Eastern NC, a moistening low-level flow is
ongoing from the Atlantic into the Carolinas. Within this flow,
there is evidence on satellite imagery of some attempt at FG or
stratus from coastal SC north into SE NC. While moisture
advection overnight is expected to be stronger than this time 24
hrs ago, it`s still unclear whether or not the depth of
moisture will be sufficient for impactful sub- VFR conditions or
not. For now, I`ve kept the TAFs as-is, with no changes to the
00z TAFs (regarding the fog/stratus potential). Stay tuned for
amendments if needed.

Any fog or stratus that develops is expected to mix out with
daytime heating on Tuesday. During the day Tuesday, gusty S to
SW winds up to ~20kt are likely with daytime mixing and the
passage of the seabreeze. With increasing moisture, I expect
more cumulus with the seabreeze today, but the risk of SHRA
still appears low (<10% chance). Late Tuesday evening, continued
moisture advection is expected to lead to the development of
mid-level CIGs ahead of an upper level wave approaching from the
west. There will be a chance of SHRA and TSRA with this wave,
but not until after the current 06z TAF cycle.

LONG TERM /Wednesday through Saturday/...
As of 330 AM Tuesday...Pred VFR expected through the period but
a few instances of unsettled weather are expected. An
approaching disturbance will bring chances for showers and
thunderstorms on Wednesday (30-60%). By Saturday, a cold front
will be moving into the area and bring another chance for
showers and thunderstorms (15-30%). Lowered CIGs and VIS are
expected during these times.

&&

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

Background northeasterly long-period swell continues through
tonight, and will combine with a modest southerly wind swell,
producing seas of 3-5 ft. Like yesterday, breezy southwesterly
winds of 10-20kt will be common through tonight, with a few
gusts to near 25kt where the thermal gradient in maximized.
Because of the marginal nature of the winds, we`ll continue to
run headline-free.

Late tonight, an upper level disturbance and a developing weak
coastal trough is expected to support an increasing risk of
showers and thunderstorms, especially for the southern
waters/rivers/sounds.

LONG TERM /Wednesday through Saturday/...
As of 330 AM Tuesday...

KEY MESSAGES

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

FORECAST DETAILS

Although marine conditions are forecast to remain below SCA
criteria, opportunities for showers and thunderstorms are
possible Wednesday and this weekend. Winds will be variable
through the period due to several systems moving through but
will remain around 5-10 kt with 2-4 ft seas.

&&

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

&&

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