859
FXUS61 KLWX 080123
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
923 PM EDT Tue May 7 2024

.SYNOPSIS...
Daily chances for showers and thunderstorms look to continue through
Thursday as multiple fronts and waves of low pressure push across
the area. A potent cold front will bring an increased threat for
severe thunderstorms and flash flooding Thursday into Friday. Rain
chances decrease into the weekend with cooler temperatures and less
humidity as high pressure nears the region.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Remaining radar returns are rapidly dissipating as of 9 PM. Only
some mid level clouds are left from an earlier line of
convection in the Ohio Valley. While a stray shower can`t
totally be ruled out this evening, it does appear most stay dry
with a lack of focus for forcing.

Eyes turn to ongoing severe convection in the Ohio Valley, with
those remnants likely approaching the area after midnight. While
severe thunderstorms are not anticipated locally, some showers
and isolated storms may continue eastward across the area late
tonight and very early Wednesday due to weak elevated
instability and a slight steepening of lapse rates associated
with the feature aloft.

Fog is looking less prevalent than previous nights, but could at
least see some patchy fog developing late, particularly behind
any showers that move through. Overnight lows will be in the 60s
for most locations.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
On Wednesday, the instability in the atmosphere will be greater
given a few more breaks in the clouds due in part to west to
southwest flow. This will allow for some downsloping and
compressional warming especially east of the Blue Ridge. The
combination of downsloping flow and subtle subsidence in the wake of
the decaying MCS Wednesday morning may inhibit a widespread
thunderstorm threat especially along and north of the
I-66/US-50 corridor. Even with that said, scattered strong to
severe storms remain, with most recent CAMs targeting the
central VA Piedmont to southern Maryland. The primary threat
for storms will be damaging winds and localized flash flooding.
Large hail up to 1" in diameter is also possible. Highs on
Wednesday will soar into the mid to upper 80s across many lower
elevation locations, with even a few areas potentially hitting
90 degrees. The mountains will be in the mid to upper 70s for
the afternoon.

Mid-level troughing continues to deepen Wednesday night into
Thursday sending a potent cold front from the Ohio River Valley
toward the region. As a result, expect increasing shower and
thunderstorm chances late Wednesday night into Thursday morning as
another impulse of energy ripples through. Flash flooding could
become a concern here given the increased PWATS above climatology
for this time of year combined with antecedent conditions from
multiple rounds of showers and thunderstorms earlier in the week.

There will be a break between the morning precipitation and the
afternoon in which the atmosphere reloads especially in areas east
of the Blue Ridge. Instability parameters increase by Thursday
afternoon just ahead of the cold front, this will allow for the
potential for strong to severe thunderstorms to develop. One
caveat is that overall thunderstorm coverage may be limited
with the enhanced cloud coverage and stabilization from morning
activity. Main threats with storms Thursday look to be damaging
winds, large hail, and localized flash flooding.

Afternoon highs Thursday will climb into the upper 70s to low 80s
for most areas. Northwest flow kicks in behind the cold front
Thursday night and will bring lows in the 40s along the Allegheny
Front with 50s further east.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
A strong cold front will track through the area early Friday. While
shower and thunderstorm chances linger, the threat for severe
weather should diminish in the wake. After spending the previous
couple of days in the 80s, temperatures will certainly cool off to
finish out the work week. Friday`s forecast highs are likely
confined to the mid 60s to low 70s, locally falling into the 50s
across mountain locales. Depending on how quickly showers come to an
end, some late day clearing is not out of the question.
Northwesterly winds will be breezy at times with gusts up to 20 to
25 mph at times. Nighttime conditions will be cool with lows
dropping into the mid 40s to low 50s.

This weekend will be a mixed bag given the cyclonic flow aloft. Each
day is forecast to carry a risk for some isolated to scattered
shower activity. High temperatures should be around 3 to 6 degrees
below average. That is, mid 60s to low 70s for most, but with mainly
50s for the mountain regions. Compared to the humidity earlier in
the week, it will feel much drier with dew points down in the 40s.
In between disturbances, there will likely be some periods of sun,
particularly by Sunday afternoon behind the next frontal system.
Expect temperatures to rebound into early next week as heights begin
to build.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
Dry conditions and mid/high ceilings are expected through the
evening and part of the late night. Remnants of convection over
the Ohio Valley may cross the area late tonight into early
Wednesday morning. Coverage of this activity is uncertain in
what will likely be a weakening state. Therefore have only
included VCSH in most of the TAFs except for MRB (higher chance
of precip being farther west). Weak elevated instability may
allow for some thunderstorms as well, but confidence is low (20
percent chance). Fog looks to be less prevalent tonight than the
past two, but patchy fog could develop, especially in the wake
of any showers.

After any early morning activity departs, coverage of
precipitation looks to be fairly limited on Wednesday at the
terminals. Light south winds tonight will turn more westerly by
Wednesday, gusting up to 20 knots for the afternoon.

Widespread showers and thunderstorms are likely on Thursday, with
some strong to severe storms possible in the afternoon to evening at
all terminals. Outside of thunderstorm activity, VFR conditions are
likely though abundant cloud cover will be in place across the
area.

Prevailing VFR conditions are expected on both Friday and Saturday,
although a passing shower could briefly drop conditions to sub-VFR
either day. Winds will be out of the northwest on Friday, and then
out of the west on Saturday.

&&

.MARINE...
Sub-SCA southerly winds are forecast through the night. A few
thunderstorms may reach the waters toward dawn but are not
expected to be strong. Winds will become westerly Wednesday and
may near SCA criteria, especially for the northern bay and upper
tidal Potomac. Thunderstorm coverage will be sparse Wednesday
afternoon and evening, with the greatest chance for the waters
surrounding southern Maryland. Additional thunderstorms may
affect the area late Wednesday night.

SCA conditions are possible over most of the local waters Thursday
and Friday due to southerly channeling. Strong to severe
thunderstorms are possible Thursday, with Special Marine Warnings
likely needed as storms move through in the afternoon and early
evening hours.

Small Craft Advisories are likely needed on Friday into Friday night
as a strong cold front tracks across the waterways. Northwesterly
winds behind this front will see a brief shift to southerlies on
Saturday. However, another frontal system approaches late Saturday
into Sunday. This is expected to bring another shot for Small Craft
Advisories during the second half of the weekend.

&&

.TIDES/COASTAL FLOODING...
Southerly winds tonight will cause anomalies to increase again.
Some of the more sensitive sites may approach Minor flood stage
with the tide cycle Wednesday morning. Thereafter, winds turn
westerly for Wednesday, which should allow anomalies to
decrease. Additional localized minor flooding is possible by
Thursday morning as winds turn southerly once again.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

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