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954
FXUS61 KLWX 231428
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1028 AM EDT Mon Sep 23 2024

.SYNOPSIS...
A front will remain stalled across the area today while strong
high pressure over eastern Canada builds southward along the
Appalachians. A strong front and area of low pressure over the
Great Lakes and Upper Midwest will approach through the middle
of the week. High pressure will build to the north mid to late
week while low pressure approaches from the south.

&&

.NEAR TERM /THROUGH TONIGHT/...
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1030 AM Update: Light to moderate showers are continuing to pass
through areas, mainly along and west of the Blue Ridge Mountains
this morning with mid to low-level clouds mixing in throughout
the entire area. We`ll see these conditions continue through the
remainder of the day today.

Previous Discussion Follows:
The Mid-Atlantic will remain shrouded in clouds thank to cool
high pressure wedging down into the region. Patchy drizzle is
possible at times, especially in easterly upslope areas as well
as east of the Blue Ridge Mountains. Also, elevated showers are
possible at times as troughing and a frontal system slowly
approach from the west. A couple of elevated thunderstorms are
possible west of I-81, but it will likely be too stable for much
if any thunder near and east of I-95.

With the clouds and onshore flow, there won`t be too much of a
swing between high and low temperatures the next 24 hours.
-- End Changed Discussion --

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Troughing and a frontal system will continue to approach from
the west Tuesday into Wednesday. Multiple shortwaves rounding
the base of the larger long wave trough (which eventually may
become a cutoff low over the TN/MS Valley) will lead to the
potential for showers and a few elevated thunderstorms at times.
There may be enough forcing with the incoming shortwave Tuesday
and Wednesday afternoons combined with sufficient instability
and shear (mainly aloft) to result in a few stronger storms
capable of a little hail, or perhaps some gusty surface winds
near and west of the Allegheny Front. Tuesday`s temperatures
look cool during the day with a wedge firmly in place, but
daytime temperatures may warm a bit Wednesday as the wedge
weakens.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Thursday is possibly going to be the driest day this week as surface
ridging across the region weakens, and mid-level ridging briefly
develops aloft. Cannot rule out a few showers, though rain chances
are only at 10-20pct across the area. This is also when we see the
warmest temps of the week, with highs in the low 80s. Plenty of
cloud cover remains, though some sunshine could peak through in the
afternoon. Mild temps Thursday night look to be in the 60s.
Highs Friday into the weekend return to seasonable values in
the 70s.

The global guidance and ensembles have come into much better
agreement over the past 24 hours for the forecast Friday into the
weekend. A mid-level cutoff low over the Mid-South/Lower MS Valley
begins to retrograde as it interacts with a possible tropical
low over the northern Gulf Coast. The guidance still diverges on
where exactly the possible tropical low goes, with a track
closer to the TN Valley/middle OH Valley possibly bringing
increased moisture and rain chances to our area late in the
week. It should be noted that models also show a Canadian high
building south across the Northeast and Mid-Atlantic, possibly
keeping moisture/rain chances to our south. While confidence has
increased given the better alignment of the long range models,
there still remains quite a bit of uncertainty in regards to
what type of weather we see here late in the week. Continue to
monitor for changes in the days ahead.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
MVFR CIGs look to persist at most TAF sites through Tuesday,
with bouts of IFR possible especially at MRB/CHO and/or during
the overnight/early AM hours each day. Conditions may improve
slightly by Wednesday. This is all thanks to onshore flow around
a wedge of high pressure over the region. Meanwhile, a frontal
system slowly approaching from the west could result in a few
showers or even an elevated thunderstorm (especially west of
I-95) through mid week. Lastly, some patchy drizzle is possible
at times in onshore flow, most likely during the AM hours.

Thursday could see some improved conditions, with some periods of
VFR CIGs in the afternoon, though still expecting abundant cloud
cover. High pressure to the north weakens, and weak ridging develops
aloft keeping conditions mostly dry. Sub-VFR conditions likely
return Thursday night into Friday, along with another round of
rain.

&&

.MARINE...
Onshore flow will mainly remain sub-SCA the next few days,
though a couple pushes of easterly flow may result in 20 kt
gusts tonight, Tuesday evening/night, and Wednesday
afternoon/evening. A few showers are possible at times as a
frontal system approaches from the west, with most thunder
chances likely remaining west of the waters until at least late
Tuesday into Wednesday.

After Wednesday night, winds are forecast to remain below SCA
levels through the end of the workweek. Surface high pressure
across the Mid-Atlantic weakens Thursday, allowing winds to
become variable around 5-10 knots. A stronger high builds in
Friday, causing a slight increase in easterly winds to 10-15
knots. These could approach SCA levels Friday night into the
weekend.

&&

.TIDES/COASTAL FLOODING...
Coastal flooding is expected to continue for most of the week as
high astronomical tides and steady onshore winds keep water levels
high. The Coastal Flood Warning for Annapolis, DC SW Waterfront, and
Alexandria has been expanded through Tuesday night. A new Coastal
Flood Warning has been issued for Straits Point. Coastal Flood
Advisories remain in place and were extended for all other locations
along the Chesapeake Bay and lower tidal Potomac River. Winds
are forecast to lessen Thursday as the surface ridge over the
region momentarily weakens. This could allow a day for water
levels to lower a bit. However, that is going to be short-lived
as strong onshore winds redevelop Friday into the weekend,
likely bringing continued minor to moderate coastal flooding.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...Coastal Flood Warning until 4 AM EDT Wednesday for DCZ001.
MD...Coastal Flood Warning until 4 AM EDT Wednesday for MDZ014.
     Coastal Flood Advisory until 4 AM EDT Wednesday for MDZ011-016-
     018-508.
     Coastal Flood Warning until 10 PM EDT Tuesday for MDZ017.
VA...Coastal Flood Warning until 4 AM EDT Wednesday for VAZ054.
     Coastal Flood Advisory until 4 AM EDT Wednesday for VAZ057.
WV...None.
MARINE...None.
-- End Changed Discussion --

&&

$$

SYNOPSIS...DHOF/CPB
NEAR TERM...DHOF/ADM
SHORT TERM...DHOF
LONG TERM...KRR
AVIATION...DHOF/ADM/KRR
MARINE...DHOF/KRR
TIDES/COASTAL FLOODING...LWX