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609
FXUS61 KLWX 230135
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
935 PM EDT Wed May 22 2024

.SYNOPSIS...
Surface high pressure will continue to shift offshore as a cold
front approaches the area from the west through tonight. The cold
front will move over the Mid-Atlantic throughout the day on Thursday
before lifting northward as a warm front Friday afternoon.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
-- Changed Discussion --
A lee trough is still apparent east of the Appalachians this
evening but otherwise notable forcing features are lacking.
However, there is still plenty of instability aloft, and that is
the reason isolated thunderstorms continue to develop over the
mountains. It seems as if any storms will have a limited
lifetime this evening however.

Additional perturbations aloft and associated convection are
also ongoing across the Ohio Valley. Given at least some limited
elevated instability may linger through the night, some of this
activity may hold together (or redevelop) and reach the area
late tonight. There`s not a clear signal in guidance for
coverage however.

Extensive cloud cover associated with this convection may limit
fog develop late tonight, but there could be some patches if
there are breaks. Overnight lows will be in the 60s for most.
-- End Changed Discussion --

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
An approaching cold front from the west will move over the Mid-
Atlantic Thursday afternoon before lifting northward as a warm
front Friday afternoon. This nearby boundary will provide
stronger forcing for daily shower and thunderstorm chances. The
threat for convection is higher on Thursday compared to Friday
with the cold front moving overhead. Cloud cover could inhibit
convection development but SBCAPE values 1500-2500 J/kg, bulk
shear around 35 knots, and lapse rates 6-7C/km will allow for at
least a conditional risk for strong to severe thunderstorms.

Showers and perhaps a thunderstorm continue overnight as the
front remains nearby. As the front lifts north of the area on
Friday, precipitation chances decrease Friday morning. Slight
chance to chance PoPs continue throughout the day with plenty of
moisture aloft.

Shortwave energy moving aloft will continue a slight chance for
showers and thunderstorms. The threat will be mostly confined to
the southern portions of the forecast area.

Temperatures will be in the 80s for most with higher elevations
staying in the mid to upper 70s. Overnight low temperatures will
be upper 50s to mid 60s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Unsettled conditions will continue through the holiday
weekend and into early next week. Strong to severe thunderstorms
will be possible Saturday through Monday, with the best chances on
the bookends of the period. A shortwave trough on Saturday will move
through the area with increasing instability during the afternoon
and evening hours. Highs will top out in the low 80s on Saturday. By
Sunday, thunderstorm chances remain but forcing may be a bit weaker
compared to Saturday, so overall coverage and intensity of the
storms may be a bit lower comparatively.

By Monday, a strong cold front will approach the area as a result of
a deep low pressure system situated near the Great Lakes region.
Strong to severe thunderstorms will certainly be possible Monday
afternoon and evening. Main hazards for this system will be damaging
winds and large hail. Afternoon highs will climb into the upper 70s
to low 80s across much of the area. Cooler and less convective
conditions arrive behind the front on Tuesday with highs in the 70s
and overnight lows dropping down into the mid to upper 50s.

&&

.AVIATION /02Z THURSDAY THROUGH MONDAY/...
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Isolated storms remain over the mountains this evening. While
it`s possible one could develop or hold together with elevated
instability remaining, it does appear the convective threat is
diminishing. There is a signal some showers, or perhaps even a
few thunderstorms, could reach the area late tonight into
Thursday morning, originating from activity currently over the
Ohio Valley. Did not include a mention of thunder at this time
given the unfavorable time of day. Winds shift to westerly by
Thursday morning and will remain out of the west through Friday
afternoon.

With various perturbations in the flow, an approaching front,
and at least some instability, showers and thunderstorms will
remain possible Thursday and Thursday evening. Some guidance
indicates there could be multiple rounds. Thus timing and
placement is highly uncertain. While a thunderstorm could occur
at just about any time, focused the mention during the afternoon
hours when instability will likely be greatest.

Diurnally driven showers and thunderstorms are possible
Friday, although overall coverage may be lower.

Sub-VFR conditions will be possible Saturday and Sunday with any
showers and thunderstorms that cross the terminals, especially in
the afternoon and evening. Winds will be fairly light out of mainly
the south.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
Winds are gradually diminishing, although a few southerly gusts
to 20 knots continue along the bay. A Small Craft Advisory is
in effect until 2 AM Thursday morning for many zones. Winds
shift to southwesterly Thursday morning before shifting to
westerly in the afternoon.

Winds remain below SCA criteria through Friday. Daily shower and
thunderstorm chances may bring hazardous conditions to the
waters with some possibly requiring SMWs.

Sub-SCA winds are expected for the weekend aside from any showers
and thunderstorms that cross the waters. Special Marine Warnings may
be needed both afternoons and evenings.
-- End Changed Discussion --

&&

.TIDES/COASTAL FLOODING...
Minor coastal flooding is possible at DC Waterfront, Annapolis,
and Havre De Grace with the high tide cycle Thursday morning.
After high tide Thursday morning, winds shift from southerly to
westerly allowing tidal anomalies to begin decreasing.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 2 AM EDT Thursday for ANZ530>534-
     537>541-543.

&&

$$

SYNOPSIS...AVS
NEAR TERM...ADS
SHORT TERM...AVS
LONG TERM...ADM
AVIATION...ADS/AVS/ADM
MARINE...ADS/AVS/ADM
TIDES/COASTAL FLOODING...AVS