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823
FXUS61 KLWX 080755
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
355 AM EDT Wed May 8 2024

.SYNOPSIS...
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Showers and thunderstorm chances continue through Thursday with
multiple waves moving through the Mid-Atlantic. A strong cold
front will bring increased chances for severe and flooding
impacts Thursday into early Friday. Precipitation chances
decrease behind the front going into the weekend with cooler
temperatures and high pressure nearing the Mid-Atlantic.
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&&

.NEAR TERM /THROUGH TONIGHT/...
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Precipitation from the decaying convection across the Ohio
Valley will continue to slowly move into the area this morning.
The strongest cells look to stay further north of the area into
PA. Nonetheless, have the chance for some showers and an
isolated thunderstorm to approach the northern half of the area
this morning, mainly before 9-10 AM. After that, conditions
improve with even some periodic breaks in the clouds.
Downsloping flow coupled with subtle subsidence in the wake of
the decaying MCS may keep the overall threat for scattered
thunderstorms down today.

There still remains an isolated threat for a few thunderstorms,
mainly across the southern most parts of the area in central VA and
southern MD later this afternoon. Essentially, if a storm is
realized, then there could be some strong to severe characteristics
to it given the convective parameters it will have to work with.
Main threats with any of these storms will be damaging winds and
large hail. With the downsloping flow in place, expect temperatures
to rise into the mid to upper 80s across most areas aside from the
mountains (mid 70s). Some lower elevations may flirt with 90
degrees, especially if enough breaks in the clouds occur. So, mainly
a fairly dry afternoon and evening with just isolated chances for a
few showers and thunderstorms, mainly across central VA and southern
MD.

By tonight, clouds will increase from the west ahead of the
approaching cold front moving in from the Ohio Valley. Rain
chances will increase from west to east, especially after
midnight, and continue through the night and into Thursday
morning.
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&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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Increasing showers and isolated thunderstorms will continue Thursday
morning ahead of the cold front passage. Expect overall QPF to be
0.50 to 1" with localized higher amounts, especially in heavier
downpours and thunderstorms. Isolated instances of flooding will be
possible, given the anomalously high PWATs coupled with antecedent
moist conditions over the last week, especially across areas along
and west of the Blue Ridge Mountains. A fairly sharp instability
gradient may develop east of the Blue Ridge just ahead of the cold
front Thursday afternoon. There is some uncertainty with this given
any earlier convection/cloud debris from early convection late
tonight into early Thursday. Should there be a lull with increasing
breaks in the clouds, then some thunderstorms may develop and become
strong to even severe. Main hazards will be damaging winds along
with large hail of 1 inch diameter or greater as a result of steeper
lapse rates.  The best chances for thunderstorms will likely be
across the VA Piedmont into southern MD. Afternoon highs will be in
the upper 60s to low 70s across the MD/PA border, with low 80s
further south across central VA.

Showers and isolated thunderstorms will linger early Friday, with
showers continuing throughout much of the day as a result of the
departing low pressure system off to the north. Cannot rule out an
isolated thunderstorm Friday afternoon. Highs will cooler as a
result of northwest flow, with mid to upper 60s across most areas
with even mid 50s across the Allegheny Front. NW winds will be
gusting 20 to 25 knots during the afternoon on Friday, with higher
gusts possible along the ridges.
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&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
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Longwave troughing will remain in place across the eastern US
this weekend. On Saturday we`ll start the day off between one
shortwave departing offshore, and another digging down the
backside of the longwave trough into the Ohio Valley. The latter
shortwave will pass overhead Saturday night into the day
Sunday.

Conditions should start off mostly sunny on Saturday within the
subsidence behind the departing shortwave. Clouds and eventually
showers will be on the increase as we progress through the afternoon
as large scale ascent ahead of the next shortwave starts to
overspread the area. Chances for showers will continue through
Saturday night and into the day Sunday as the upper trough axis
moves overhead. High temperatures this weekend are forecast to reach
into the upper 60s and lower 70s, while low temperatures will
generally be in the 40s to lower 50s.

Upper troughing will progress off to our east early next week,
allowing heights to start rising aloft. Such a pattern will lead to
drier conditions and a warming trend in temperatures. Highs are
expected to reach into the low-mid 70s on Monday, and into the mid-
upper 70s on Tuesday.
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&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
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Remnants of a decaying MCS this morning will bring mainly an
isolated chance for a few showers across the terminals through 12-
13z. Kept VCSH for all terminals aside from KCHO. Some patchy fog
may be possible this morning, especially across areas that received
rainfall recently are in the clearer air with light winds.
Precipitation chances weaken for much of the day today with no real
appreciable chances across the terminals. Decided to keep any
precipitation out of the TAFs for this afternoon/evening. Will
continue to monitor any potential needs for additions. Westerly
winds will gust up to 20 knots this afternoon.

Widespread showers and thunderstorms are likely Thursday, with some
strong to severe storms possible for the afternoon and evening
hours. Best chances for this to occur would be across the I-95
corridor terminals. VFR conditions are likely outside of the
thunderstorm activity. These conditions will likely continue into
Friday with gusting NW winds 20 to 25 knots throughout the day.

Prevailing VFR conditions are expected at the terminals this
weekend, but passing showers could lead to temporary drops to sub-
VFR either day. Winds are forecast to be out of west to southwest on
Saturday, and then out of the northwest on Sunday.
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&&

.MARINE...
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Westerly winds may near SCA criteria this afternoon, especially
across the northern bay and upper tidal Potomac. There are still
uncertainties with this but will continue to monitor the trends for
any needed issuances. Cannot rule out an SMW across the southern
water especially this afternoon with any strong thunderstorms that
cross the waters but confidence is low in this occurring.

SCAs are possible Thursday and Friday as a result of southerly
channeling. SMWs will be possible Thursday afternoon ahead of a cold
front passage bringing heavy showers and thunderstorms over the
waters.

Winds may near low-end SCA values in west to southwesterly flow on
Saturday, and then again in northwesterly flow on Sunday.
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&&

.TIDES/COASTAL FLOODING...
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Water levels remain elevated in southerly flow this morning. Coastal
Flood Advisories are in effect for the ongoing tide cycle at
Annapolis, Straits Point, and DC. Westerly winds should allow water
levels to decrease this afternoon. Winds turn southerly again late
tonight into tomorrow morning, which could lead to additional Minor
flooding at the most sensitive sites.
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&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...Coastal Flood Advisory from 7 AM to 11 AM EDT this morning for
     DCZ001.
MD...Coastal Flood Advisory until 9 AM EDT this morning for MDZ014.
     Coastal Flood Advisory until 5 AM EDT early this morning for
     MDZ017.
VA...None.
WV...None.
MARINE...None.
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&&

$$

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