960
FXUS61 KLWX 290139
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
939 PM EDT Sun Apr 28 2024

.SYNOPSIS...
Very warm temperatures for late April are expected today through
Tuesday as high pressure sits off the Mid-Atlantic coast. Shower and
thunderstorm chances return Tuesday afternoon and again Wednesday as
a cold front crosses the region. High pressure briefly returns
Thursday before another front arrives late week and into the weekend
with additional afternoon showers and thunderstorms.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Just a few high clouds remain in place this evening. Mostly
clear skies are expected through the overnight hours. Winds
will be light out of the south to southwest, with some locations
eventually going calm. Overnight lows will be in the upper 50s
to lower 60s for most.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
The strong upper level ridge continues to strengthen Monday as
surface high pressure drifts further off the southeast U.S coast.
This will yield a continuation of dry conditions and perhaps the
first 90 degree day of the year in many locations across the region.
Afternoon highs will reach into the mid to upper 80s for most with
lower 90s along the I-95 corridor south into the central VA
Piedmont. An isolated thunderstorm cannot be ruled out over the
mountains with chances less than 20 percent given a capping
inversion overhead. Mild conditions will continue Monday night with
lows remaining mild in the low to mid 60s.

Changes look to arrive Tuesday as the ridge begins to buckle. An
upper level trough and associated cold front look to push in from
the Great Lakes and Ohio River Valley Tuesday afternoon and evening
bringing renewed chances for showers and thunderstorms. A few of
these storms could be strong to severe although the chance for
widespread severe weather appears limited. This is due in part to
weak 0-6 km deep layer shear at 30 kts or less and lower dewpoint
values in the upper 50s and lows 60s. SPC currently keeps the area
in general thunder while the CSU learning probabilities
highlight areas east of the Blue Ridge for 15-30 percent
probabilities for a marginal risk of severe weather. With all
that said, any storms that do develop will be capable of
producing frequent lightning gusty winds, and locally heavy
rainfall (PWATS running 1-1.5"). High temperatures Tuesday will
push back into the mid to upper 80s with 70s over the
mountains/near the bay.

Shower and thunderstorm activity will gradually diminish in the
wake of the front Tuesday evening into Tuesday night.
Temperatures will fall back into the upper 50s and low 60s with
the front sitting south and east of the region. Areas of patChy
dense fog are also possible especially in areas that do see the
rain.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The front will still be progressing south through the area Wednesday
while a shortwave trough aloft passes to the south. A chance of
showers and perhaps even thunderstorms will linger depending on the
timing of these features. While temperatures will trend downward,
they will still remain around 10 degrees above normal, in the upper
70s and lower 80s. High pressure will be building southward from New
England Wednesday night with slightly cooler lows in the 50s.

Upper level ridging will build over the area Thursday, promoting dry
conditions. With the high progressing southward and low pressure
approaching the western Great Lakes, the warm sector will quickly be
established and temperatures will remain 5-10 degrees above normal.

The Great Lakes system will be on more of a northern trajectory as a
trough ejects through the northern Plains. As a result, chances for
rain have slowed for Friday, with a chance for a few showers and
storms mainly confined to the mountains. The trailing front will
eventually reach the area Saturday or Saturday night. The highest
chance for showers will be during this period. While thunderstorms
will be possible, instability will likely be fairly limited.

There remains enough ensemble spread in frontal/trough timing that a
chance for showers lingers into Sunday. Even if we are solidly
 by that time, temperatures are forecast to remain above normal
as a zonal flow is in place aloft.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
VFR conditions are expected at all TAF terminals through the valid
TAF period. Some diurnal strato-cumulus can be expected this
afternoon and again Monday between 5-7kft. Outside of the passing
mid and high level clouds there remains the potential for
valley fog overnight into Monday morning. The highest confidence
for fog looks to occur at KMRB, KSHD, and KCHO due to their
proximity to bodies of water. Some fog is also possible at KIAD
and KBWI/KMTN, but for now left out due to confidence. Winds
will remain light out of the south and southwest at 5-10 knots
through Monday afternoon before switching to the west and
southwest heading into Tuesday.

The next chance for sub-VFR conditions arrives with a cold front
Tuesday afternoon and evening. This front will bring renewed chances
for scattered showers and thunderstorms. The strongest storms will
be capable of producing wind gusts over 35 knots, frequent
lightning, and brief vsby reductions from locally heavy rainfall.
Any shower or thunderstorm activity moves east of the area late
Tuesday evening into Tuesday night.

A few showers and thunderstorms remain possible Wednesday as an
additional weak cold front slowly pushes through the area. Otherwise
VFR conditions will continue through Thursday.

&&

.MARINE...
Favorable marine conditions are expected through Monday night as
high pressure brings warm and dry conditions to the waters. Winds
will remain out of the south and west today at 5-10 knots
before turning to the west and southwest Monday.

A cold front is set to cross the local waters Tuesday afternoon and
evening bringing scattered showers and thunderstorms. These storms
will be capable of producing wind gusts of 35+ knots, frequent
lightning, and locally heavy rainfall. Special Marine Warnings may
be needed as these storms cross the waters Tuesday afternoon.
Showers and thunderstorms push east of the waters Tuesday evening
into Tuesday night. Winds will turn back toward the northwest at
this point, but should remain below SCA levels during this time.

Northwest winds may come close to SCA criteria Wednesday as a cold
front pushes to the south. A thunderstorm is also possible. Winds
will become southerly again Thursday and Friday. Marginal SCA
conditions could occur in channeling on the bay in the
evening/overnight each day.

&&

.TIDES/COASTAL FLOODING...
No further tidal flooding is expected over the next several high
tide cycles. A few sites could flirt with action stage Monday
morning under light south to southwesterly flow. It`s not until
Tuesday when tidal levels get close to minor thresholds.

&&

.CLIMATE...
Near-record to record warmth is possible on Monday afternoon.
Below is a list of record high temperatures for April 29th, and
the year the record was set.

                                       Apr 29th
Climate Site                  Record High     Forecast High
Washington-National (DCA)     91F (2017+)     91F
Washington-Dulles (IAD)       89F (2017)      89F
Baltimore (BWI)               91F (1951)      89F
Martinsburg (MRB)             93F (1974)      86F
Charlottesville (CHO)*        92F (1974)      89F
Hagerstown (HGR)*             90F (1974)      86F
Annapolis (NAK)*              92F (1974)      83F

+ denotes that multiple years reached this value, but the depicted
  year is the most recent
* denotes sites where Record Event Reports (RERs) are not issued

&&

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

&&

$$

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