134
FXUS61 KLWX 180111
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
911 PM EDT Sat Aug 17 2024

.SYNOPSIS...
Widely scattered to numerous showers and thunderstorms are expected
through Sunday as a slow moving cold front passes through the
region. The highest thunderstorm chances look to occur Sunday
afternoon and evening as the front sits overhead. Additional showers
and thunderstorms are possible Monday as the front pushes toward the
coast. Cool Canadian high pressure builds over the region Tuesday
and last through the remainder of the upcoming workweek.

&&

.NEAR TERM /THROUGH SUNDAY/...
Shower and thunderstorm activity will greatly decrease in intensity
and coverage late this evening and overnight compared to earlier
today. As lingering afternoon activity exits to the east across
the central Chesapeake Bay, additional isolated to sporadic
showers and perhaps a rumble of thunder could develop near the
mountains and areas to the east. Tonight`s low temperatures will
bottom out in the middle 60s to lower 70s. Some patchy fog may
also develop toward daybreak Sunday as dewpoint temperatures
will likely be in the upper 60s to lower 70s.

The threat of showers and thunderstorms will remain increased
across the region Sunday into Sunday evening with multiple
shortwave troughs of low pressure passing overhead. Sunday`s
environment looks similar to Saturday with CAPE values of a
1000-2000 j/kg and 0-6 km bulk effective shear values of 25-35
kts. SPC has upgraded areas near and east of I-95 to a slight
risk of severe thunderstorms Sunday. Main concern Sunday would
be wind as some linear organization will be possible with better
dynamics in place in advance of the main trough. Besides the
severe threat, locally heavy rainfall continues to be a concern
with PWATS hovering between 1.50 to 1.75 inches mainly east of
the Blue Ridge. Isolated instances of urban flooding could occur
especially across central and northeast MD (including Baltimore
metro) given the recent rounds of rainfall as the front is slow
to pass through.

High temperatures Sunday will once again be reliant upon how much
sun breaks through. Most locations east of the Alleghenies will push
into the mid to upper 80s. Mountain locations will be cooler in the
mid to upper 70s.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
Overnight lows Sunday night will fall into the mid to upper 60s
and low 70s.

Shower and thunderstorm chances will linger into Monday although
coverage will decrease as the front pushes east with the upper
level trough axis lagging behind.

Additional showers and spotty thunderstorms are likely to
linger into Monday as the upper level low digs further south
behind the departing frontal boundary. With that said, any
thunderstorm activity that may form mainly east of the Blue
Ridge will have the potential for a little hail given the colder
air aloft and steepening lapse rates. Overall convective
parameters will be far less compared to Sunday given the switch
toward more of a west to northwest flow. There is a marginal
risk for severe weather mainly from Washington DC south and
east. Outside of the storm chances Monday winds will pick out
out of the west and northwest ushering in cooler and drier air.
Gusts of 20-25 mph are possible during the afternoon and evening
hours yielding highs in the mid 60s over the mountains to mid
80s within the I-95 corridor. Overnight low temperatures Monday
night will be in the mid to upper 50s and low 60s.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Quiet conditions locally will persist through much of next week as
Canadian high pressure dominates the region through at least Friday.
Only noticeable precip chances will be Tuesday afternoon across
northeast MD where the departing upper trough will continue to shift
further east. Afternoon highs will start out below normal on
Tuesday, with mid to upper 70s for most areas east of the
Alleghenies. Temps will continue to warm up as the week progresses
before highs on Friday reach the low to mid 80s for the lower
elevations.

Similar trends in the overnight lows with some areas along the
Allegheny Front reaching the low 40s with low to mid 50s expected
further east. Would not be surprised to see some of the valleys make
a run at below 40 degrees Tuesday night. A slow warming trend in the
overnight lows will end the workweek with lows in the mid to upper
50s for most areas on Friday. Winds will remain elevated Tuesday
with the departing upper trough, gusts out of the northwest could
reach 20 mph at times in the afternoon and evening before
dissipating for the remainder of the work week.

&&

.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Additional showers could develop and move toward KMRB heading
into the overnight hours as an additional shortwave trough
pushes through. By Sunday, expect increased shower and
thunderstorm chances for all terminals during the afternoon and
evening hours. Some storms could be strong to severe with wind
as the primary concern as the cold front and upper level trough
swing into the region.

Outside of the shower and thunderstorm chances expect sustained
southerly winds between 5 to 10 kts gusting upwards of 15 to 20 kts
at times this evening. Similar winds are expected Sunday.

Sub-VFR ceilings will be possible at times Monday afternoon and
evening with additional shower and thunderstorm chances as one last
piece of shortwave energy pivots through. Winds will switch to
the west and northwest with gusts up to 20 kts.

VFR conditions are expected Tuesday and Wednesday with gusty
northwesterly winds 15-20 knots in place Tuesday afternoon and
evening before high pressure builds in by Wednesday with prevailing
VFR conditions expected.

&&

.MARINE...
SCAs have been extended into Sunday afternoon with southerly
winds gusting 20 to 25 kts. Additionally, showers and
thunderstorms are possible each afternoon and evening bringing
stronger gusts to the waters. Stronger storms could require
Special Marine Warnings on this afternoon and again on Sunday as
a cold front pushes through.

SCA winds are possible Monday afternoon and night for the
waters as the pressure gradient remain amplified over the
region. Cannot rule out an isolated SMW Monday afternoon/evening
if any thunderstorms cross the waters. SCA winds are becoming
increasingly likely Tuesday as an upper trough departs to the
east and high pressure builds in from the northwest. These winds
should diminish Wednesday and into the remainder of the work
week.

&&

.TIDES/COASTAL FLOODING...
Water levels will remain elevated under increased southerly flow
through the remainder of the weekend. Expect additional minor
flooding concerns over the next 3 high tide cycles at Havre de
Grace, Annapolis, and DC Waterfront. Annapolis may come close to
moderate flooding threshold for the Sunday morning high tide
cycle, and Baltimore and Solomons will be close to minor. This
is backed up by both the ETSS and CBOFS model guidance. Water
levels will drop with offshore flow developing early next week.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 8 AM EDT Sunday for MDZ008.
     Coastal Flood Advisory until 9 AM EDT Sunday for MDZ014.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 8 AM EDT Sunday for ANZ530>534-
     537>543.

&&

$$

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