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356
FXUS62 KILM 082325
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
725 PM EDT Wed May 8 2024

.SYNOPSIS...
A typical summer time pattern will lead to daily showers and
thunderstorms through Friday, sparked by a series of shortwaves
moving across the area. A cold front Friday night will bring
much cooler and drier air for the weekend and start of next
week. Rain chances return for the middle of next week.

&&

.UPDATE...
-- Changed Discussion --
Quick update for pops mainly on a nowcast basis via radar. Added
fog to a good part of the area based on what is now becoming a
somewhat significant rainfall event is some areas.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH THURSDAY/...
A Severe Weather Watch has been issued for our inland counties
(mainly along I-95) through 10pm this evening. Convective activity
has been over-performing just east of the Appalachians this
afternoon, and will continue moving east-southeastward ahead of a
weak shortwave. How far into our CWA storms get is still
questionable. Chances are best along I-95 with lower confidence
closer to the coast where drier air lingers aloft (as seen by
shallow diurnal cu field). MLCAPE values are already above 2000
J/kg, with MUCAPE over 3000. Any storms that do make it into our
area have a decent chance of becoming severe, with large hail and
strong winds main threat.

Well above normal low temps tonight around 70F with partly cloudy
skies. A cluster of storms, possibly MCS, will be moving across the
Carolinas overnight. Given time of day, any workover of the
environment this evening, and storms moving over the mountains, not
expecting the cluster/MCS to maintain strength as it reaches our
area. Any rain that does move through overnight/early morning has
low chance for thunder and even lower chance of any severe threat.

Yet another shortwave/storm cluster is progged to move across the
Southeast tomorrow morning into the afternoon, this time with more
of a focus for our northeast SC counties. Our entire CWA is in a
slight risk (2 out of 5) for severe weather again Thursday.
Confidence isn`t the greatest - will have a better idea after any
activity moves across through morning and if there is lingering
cloud coverage early Thursday. Forecasted CAPE isn`t as abundant as
today, but still near 2000 J/kg Thursday afternoon. Bit more shear
Thursday, with winds over 30 kts not far above the surface (which
will also contribute to a breezy day). High temps Thursday near 90F.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
Flat flow aloft will move a series of weak shortwaves across the
area. The first moves overhead Thu night with any associated
convection shifting offshore during the evening hours Thu. Post wave
subsidence arrives Thu night, ending any convective threat for the
remainder of the overnight. Some clearing Thu night, but still at
least some cloud cover will hang around into Fri. Forecast soundings
show the post wave subsidence and dry air very well, with
precipitable water dropping under 1" Thu night.

Strong southwest flow Fri morning ramps up moisture, increasing
precipitable water to near 1.7" for early afternoon. Surface based
instability "only" peaks around 2k J/kg, due to cloud cover and the
mid-level support, associated with the second shortwave, arriving
around midday instead of around peak heating. Low level jet will be
35-40kt at 3k ft on Fri with LIs around -6. All of this suggests the
potential for an isolated strong to severe storms in the area midday
to early afternoon Fri. The big question remains down to the timing.
Several factors will need to come in line to warrant more than the
current marginal risk. If timing were to be delayed a few hours and
parameters instead came in line mid to late afternoon, the severe
threat could be higher. Something to keep an eye on.

The second shortwave moves east of the area late Fri afternoon with
a cold front crossing the area in the evening. A significant amount
of cool/dry air moves in Fri night into Sat with temps dropping from
above climo temps Thu night and Fri to near climo by Sat
morning.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Much cooler and drier for the weekend and start of next week
following the passage of a cold front late Fri. Weak troughing at 5h
on Sat is reinforced by shortwave crossing the Mid-Atlantic Sat
night into Sun. This feature helps drive a dry, secondary cold front
across the area Sun morning. Front is dry because precipitable water
drops under 0.50" Sat and remains below the 10th percentile, about
0.70", into Mon afternoon. Additionally, most of the dynamics with
the shortwave pass north of the area. Moisture does start to
increase late Mon as surface high slips off the coast and weak
shortwave ridge at 5h shifts offshore. Increasing southwest flow, at
the surface and aloft, ahead of southern stream shortwave pushes
pwats over 1.8" Tue into Wed. Although forcing is limited Tue/Wed
given the path of the shortwave Tue/Wed, instability, decreasing
heights and abundant moisture will lead to elevated rain chances for
the middle of next week. Temperatures will be near to below climo
through Wednesday.

&&

.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
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Thunderstorms affecting inland sites currently although activity
finally appears to be weakening ever so slightly. VFR conditions
will return in a few hours but may be short lived as heavy rain
areas may see quick fog development. However a second shortwave
on the heels of this one may produce more showers and
thunderstorms early Thursday negating the fog development. Used
a compromise of 3 SM BR in most areas noting that IFR
conditions could develop quickly. For Thursday expecting a
repeat of today with good coverage of TSRA in the
afternoon/evening.

Extended Outlook...Threat of more widespread strong convection
with periodic flight restrictions possible later Thu into Fri
ahead of a strong CFP. High pressure to prevail late Fri into
the weekend with VFR dominating.
-- End Changed Discussion --

&&

.MARINE...
Through Thursday:
Southwest winds continue to prevail across the local coastal
waters around offshore high pressure. Tightened gradient
tomorrow afternoon will increase winds a bit, with SW winds
sustained around 15-20 kts and gusts to 25-30 kts possible for a
few hours tomorrow afternoon. Given the brief window and
forecasted sustained winds below 25 kts, have held off on any
SCA during this forecast package. Seas around 4 feet tonight
through tomorrow, with a few 5 footers Thursday afternoon,
primarily as a SSW fresh swell and a persisting weak E long
period swell mixed in. Chance for thunderstorms to move off the
coast over the waters late Thursday afternoon.

Thursday night through Monday:
Southwest flow around 20 kt Thu night into Fri will become
offshore late Fri evening as cold front moves across the waters.
Offshore flow 15-20 kt Fri night drops to around 10 kt Sat.
Winds briefly back to southwest later Sat but then a dry cold
front moves across the waters Sat night. Winds briefly increase
to 10-15 kt ahead of the front, but then drop back to 10 kt Sun
and stay 10 kt or less through Mon. Offshore flow returns and
persists into Sun night. Surface high to the north slowly shifts
east early next week, with offshore flow veering to northeast
late Sun night into Mon. Onshore flow sets up Mon with weak
gradient allowing the sea breeze to be the main driver of wind
direction.

Seas 3-5 ft Thu night and Fri starts to decrease Fri night as
offshore flow sets up, ending up 2-4 ft daybreak Sat. Seas continue
trending Sat, dropping to around 2 ft and staying around 2 ft
through Mon. A weak easterly swell will persist through Monday, but
the wind wave will be dominant. Initially it will be the southerly
wind wave, but with offshore flow developing Fri night the wind wave
will be more northerly.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
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NC...Beach Hazards Statement until 8 PM EDT this evening for NCZ106-
     108.
     Coastal Flood Advisory until 1 AM EDT Thursday for NCZ107.
SC...Beach Hazards Statement until 8 PM EDT this evening for SCZ054-
     056.
MARINE...None.
-- End Changed Discussion --

&&

$$

SYNOPSIS...ILM
UPDATE...15
NEAR TERM...VAO
SHORT TERM...III
LONG TERM...III
AVIATION...SHK
MARINE...VAO