Severe Thunderstorm Warning 121, NWS Baltimore/Washington

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
313 PM EDT Sat Jul 1 2017

.SYNOPSIS...
A cold front will pass through the area this evening. Another
cold front will move into the area Monday into Tuesday. High
pressure will develop over the Atlantic for Wednesday before low
pressure and its associated cold front possibly impacts the
region Thursday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Main concerns are in the next few hours as squall line ahead of
the cold front approaching from the northwest. Best trigger and
shear is north, while moisture/CAPE increases south, but
without trigger down south very far, expect most severe to stay
in central and northern portion of CWA, where severe box is
currently positioned. Do not expect much beyond the initial line
so will likely be able to cancel much of the box early.

Otherwise, drier air will begin to push into the region this
evening behind the front, resulting in lowering dew points and
ultimately a slightly more comfortable night than last night.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Dew points will be noticeably lower on Sunday, but temperatures
will remain quite warm, with highs similar to today's expected.
With much less forcing and lower dew points, expect much less
thunderstorm coverage, but meso models are showing some isolated
convection during the afternoon and evening, possibly associated
with a jet max. This will need to be monitored.

Not much air mass change from Sunday to Monday, though there is
a modest increase in moisture ahead of the next front. This will
couple with another approaching front to result in a slightly
more widespread threat of thunderstorms Monday
afternoon/evening, along with an isolated/marginal severe
threat. This looks more likely to stay NW of the metro, but some
lingering activity could reach the metro itself at night. Highs
Monday will again reach similar readings to today (Saturday).

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
A boundary will stall over our area on Tuesday into Wednesday
as a low pressure develops south of the Great Lakes. Southerly
flow will advect moisture into our area during this time and
some diurnally driven showers and thunderstorms are possible
Tuesday July 4th and Wednesday afternoon into the evening.

The low will move east-northeast across the Ohio Valley and
will lift the boundary as a warm front late Wednesday night into
Thursday as it approaches. Showers and thunderstorms possible
as low pressure moves across our north and into New England
Thursday into Friday. It will push a cold front through our area
early on Friday and another one will move through early on
Saturday. Conditions should improve behind this front on
Saturday.

High temperatures during this period will be near 90 degrees
along the I-95 corridor, upper 70s and low to mid 80s elsewhere.

&&

.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
Main concern next few hours is thunderstorms, potentially
severe, affecting the terminals, with damaging winds and large
hail possible along with brief IFR cigs/vis in heavy rain. After
that's over, it should be VFR through Monday night, as dry air
moving in should prevent fog and we also don't expect low
clouds either. Could still be a stray thunderstorm Sunday
afternoon/evening as well as Monday afternoon/evening.

Dry/VFR conditions expected early on Tuesday. Maybe a few
showers and thunderstorms possible in the afternoon as a
boundary stalls over us. A few showers and thunderstorms
possible again Wednesday and Thursday with boundary stalling and
slowly moving away from us. Sub-VFR periods possible Tuesday
afternoon into Thursday.

&&

.MARINE...
SCA continues until 9PM for lingering SW winds ahead of
approaching front. Special Marine Warnings also affecting the
waters as storms move in this afternoon. After that, looks like
we stay sub-SCA through Monday night with weak pressure gradient
between fronts.

Dry conditions expected early on Tuesday. Maybe a few showers
and thunderstorms possible in the afternoon as a boundary stalls
over us. A few showers and thunderstorms possible again
Wednesday and Thursday with boundary stalling and slowly moving
away from us. Wind gusts will increase on Thursday, maybe
needing a small craft advisory.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 9 PM EDT this evening for
     ANZ530>543.

&&

SYNOPSIS...RCM
NEAR TERM...RCM
SHORT TERM...RCM
LONG TERM...IMR
AVIATION...IMR/RCM
MARINE...IMR/RCM

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