297
FXUS61 KLWX 291403
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1003 AM EDT Mon Apr 29 2024

.SYNOPSIS...
Strong high pressure off the southeast U.S coast will result in near
record warmth and mainly dry conditions today. Unseasonably warm
temperatures continue Tuesday despite renewed chances for showers
and thunderstorms as cold front crosses the region. Additional
showers and thunderstorms are possible Wednesday for portions of the
area as the front is slow to sink south and east. High pressure
briefly returns Thursday into Friday before another cold front this
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
The new NWS Experimental HeatRisk has most of the area under a
Moderate Risk for heat-related impacts today. Temperatures today are
running 15 to 25 degrees warmer for highs and 10 to 15 degrees above
normal for lows for this time of year. This level of heat this early
in the season could cause impacts to heat-sensitive populations,
including those outdoors and without adequate cooling/hydration.
Additional information about HeatRisk can be found at
wpc.ncep.noaa.gov/heatrisk.

It`s a mild start to what will be a hot Monday ahead thanks to
strong upper level ridging and surface high pressure 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. Mountain locations will be a touch
cooler in the upper 70s and low 80s. Humidity values will remain in
check with dewpoints in the mid to upper 50s and low 60s. Heat index
values as a result will remain below 95 degrees. An isolated late
afternoon and evening thunderstorm cannot be ruled out over the
mountains with chances less than 15 percent given weak
upslope/orographic lift and instability build up during the course
of peak heating. Scattered to widespread convection will be stunted
due largely in part to the upper level ridge and a mid-level capping
inversion overhead. Skies will remain mostly sunny otherwise with
scattered to broken mid-high level strato-cumulus clouds building up
especially around the terrain/near the waters this afternoon.

Any shower and thunderstorm activity will quickly diminish after
sunset although cloud cover will gradually increase from the west
as a cold front pushes toward the region. As a result, little relief
is expected overnight with lows in the low to mid 60s.


&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
The ridge aloft moves east Tuesday as an upper trough and associated
cold front approach from the west. The latest models indicate a
slower moving trough that reaches the area Tuesday afternoon, and
finally moving east of the area Wednesday night.

This is going to generate a couple rounds of showers and storms
across the area, beginning Tuesday afternoon as a cold front crosses
the area. Scattered to widespread showers and scattered
thunderstorms develop Tuesday early afternoon west of the Blue
Ridge, pushing east of the Blue Ridge late afternoon into the
evening. Most shower/storm activity dissipates by late evening,
though isolated showers will be possible through the overnight.

Come Wednesday morning, the main upper trough is forecast to be east
of the Blue Ridge and the cold front east of the area. A reinforcing
upper trough quickly crosses the area Wednesday, helping to produce
scattered showers, mostly along/east of I-81. Some instability
present east of the Blue Ridge should allow some thunderstorm
activity in the afternoon. The entire system moves east of the area
by Wednesday evening as dry conditions return.

The prospects for severe storms on Tuesday continue to be low given
low instability and very weak shear. If any strong storms do
develop, they are most likely to occur west of the Blue Ridge
Tuesday afternoon. Any strong storm will be capable of producing
wind gusts of 40-50mph, in addition to frequent lightning strikes.

Well above normal temperatures continue through mid week as highs
reach the mid to upper 80s Tuesday, and low to mid 80s Wednesday.
Very mild Tuesday night lows in the low to mid 60s, cooling slightly
to the mid to upper 50s Wednesday night behind the front.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
After a weak frontal passage Wednesday, strong ridging builds over
the East Thursday and holds through the end of the week. The ridge
pattern begins to break down Sunday as a weakening southern stream
disturbance approaches from the west. A slow moving and decaying
frontal zone will attempt to cross the area early next week bringing
the threat of showers and thunderstorms Sunday. Moisture looks
plentiful, but both forcing and instability look weak to support any
significant threat of either severe wx or flooding.

By Monday, the front appears to push far enough south to limit PoPs,
but treating this like a summer front, when models are too fast in
pushing fronts through the area.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
VFR conditions are expected today and tonight as high pressure over
the region brings mostly dry and hot conditions. A few showers and
storms are possible around MRB late this afternoon, though coverage
is too low to include in TAF at this time.

A cold front will cross the area Tuesday afternoon and evening,
bringing scattered showers and thunderstorms to all terminals. Some
storms will be capable of producing wind gusts over 35 knots and
lightning strikes, as well as brief periods of reduced visibility.
Most convection dissipates Tuesday evening, though some shower
activity could linger across the area Tuesday night.

A second reinforcing upper trough moves across the area Wednesday,
causing scattered showers to develop. Some thunderstorms are also
possible Wednesday afternoon east of the Blue Ridge. This activity
quickly moves east of the area by Wednesday evening.

Outside of shower/storm activity, VFR conditions are expected
Tuesday and Wednesday.

No sig weather is expected Thu or Fri.

&&

.MARINE...
Favorable marine conditions likely today through Tuesday morning as
high pressure brings mostly dry and warm conditions to the local
waters.

A cold front will cross the waters Tuesday late afternoon to
evening, bringing scattered showers and thunderstorms. Some of these
storms will be capable of producing wind gusts of 35 knots or
greater and lightning strikes. Special Marine Warnings may be needed
as these storms cross the waters. Most of the shower and storm
activity dissipates by late Tuesday evening.

Southerly channeling is possible Tuesday afternoon and evening ahead
of the front, which could produce a period of SCA conditions in the
open waters of the Chesapeake Bay.

Winds are forecast to remain below SCA criteria Wednesday.

SCA conditions possible Friday into the weekend.

&&

.CLIMATE...
Near-record to record warmth is likely this 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+)     92F
Washington-Dulles (IAD)       89F (2017)      91F
Baltimore (BWI)               91F (1951)      90F
Martinsburg (MRB)             93F (1974)      88F
Charlottesville (CHO)*        92F (1974)      90F
Hagerstown (HGR)*             90F (1974)      88F
Annapolis (NAK)*              92F (1974)      85F

+ 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...KRR/EST
SHORT TERM...KRR
LONG TERM...LFR
AVIATION...LFR/KRR
MARINE...LFR/KRR
CLIMATE...LWX