Hail and Damaging Wind in Maryland, April 15, 2023

Area Forecast Discussion...UPDATED
National Weather Service Baltimore MD/Washington DC
1031 AM EDT Sat Apr 15 2023

.SYNOPSIS...
An area of weak low pressure will slowly cross the area today.
A strong cold front will cross the region Sunday night. High
pressure will gradually build in through at least the first half
of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...

Upper low is currently moving across the area this morning and
will exit the area to the northeast by this evening. Skies have
cleared on the backside of the low. Showers over Frederick
County MD have been training and MRMS estimates indicate
localized amounts of up to 2 inches may have fallen there
already. 12Z IAD sounding supports training convection while
model guidance show winds turning more westerly during the mid
afternoon with convection likely picking up some movement.

Expect showers to fill later this afternoon mainly 18Z-21Z time
frame due weak low level convergence and increasing instability.
Expect activity to start exiting the area or weakening by 00Z
tonight.

Highs today will be in the 70s for most, with 60s in
the mtns. Lows tonight will be in the 50s, with near 60 along
the waters.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
A more potent/dynamic shortwave will become negatively tilted as
it moves into the Great Lakes Sunday before closing off Sunday
night given favorable dynamics. Locally, an associated cold
front will approach from the west Sunday before passing Sunday
evening. High temperatures Sunday will once again be well above
climo norms, with mid 80s for most ahead of the cold front. There
remains subtle differences in timing between guidance of this
frontal passage, but overall consensus is a late evening frontal
passage. Although timing is in the unfavorable part of the
diurnal cycle, a thin ribbon of instability along the front with
strong directional convergence could result in a line of low-
topped storms capable of gusty winds Sunday night given the
presence of both low and deep layer shear. Lows Sunday night
will be in the 40s west of the Blue Ridge, with 50s to the east.

Come Monday morning, the UL low will be moving into Ontario.
Locally, west to northwest from will increase through the day.
Clouds look to be focused along the Alleghenies and Mason-Dixon
where moisture in soundings are better. Upslope rain/snow
showers are also possible, especially Monday night into early
Tuesday morning. There remains some uncertainty with the wind
forecast Monday into Monday night given the location of the
parent features causing the winds. Have kept most areas west of
the Blue Ridge gusting in the 35-45 mph range at this time. Highs
Monday generally close to climo norms (60s to near 70) aside
from the Alleghenies where they will be stuck in the mid 40s for
highs. Lows Monday night will be in the 40s for most with 30s
possible west of the Blue Ridge. Winds remaining elevated should
alleviate any frost/freeze concerns.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Any upslope snow along the Allegheny Front should come to an end by
early Tuesday afternoon. Otherwise dry and breezy conditions are
forecast for the middle part of next week. A large upper trough just
north of the area is forecast to slowly move northeast on Tuesday,
then quickly move away from our area on Wednesday. Broad ridging
develops through Thursday. Models are hinting at a weak shortwave
trough passing overhead Thursday that could produce a low chance of
rain, but confidence in that is very low at this time.

Afternoon temperatures steadily increase from the the 50s/60s on
Tuesday to 80s on Thursday and Friday. Tuesday night brings below
normal temperatures as lows settle in the mid to upper 30s west of
the Blue Ridge, and upper 30s to mid 40s east. Overnight lows return
to seasonal values over the following nights, with lows in the 50s
by Thursday night.

The strongest gradient winds are forecast on Tuesday, where the
mountains could see sustained west winds of 20-25mph with gusts up
to 45mph, and the lower elevations see winds of 15-20mph with gusts
of 25-30mph. Breezy conditions continue Wednesday afternoon as
northwest winds gust up to 25-30mph. A weak surface high moves east
of the area Thursday, causing winds to decrease and veer southerly.
The next chance of rain is on Friday when a pre-frontal trough ahead
of an approaching cold front reaches the area, bringing isolated to
scattered afternoon showers.

&&

.AVIATION /14Z SATURDAY THROUGH WEDNESDAY/...
Episodic showers and a few thunderstorms may also provide brief
restrictions through today. Winds should be relatively light
out of the south at 5-10 kts. Winds shift to west and northwest
Saturday night; where winds stay light, lingering moisture could
result in fog.

VFR conditions most of the day Sunday. As a strong cold front
approaches Sunday evening, and crosses Sunday night, showers
and a few thunderstorms are possible. This could result in brief
restrictions. Southerly winds Sunday will pivot back to west
and northwest Sunday night into Monday. Gusts around 20 kts are
possible at times.

VFR conditions and elevated winds are expected Tuesday and
Wednesday. Sustained west winds 15-20KT with gusts up to 30KT are
forecast for Tuesday. Winds decrease Tuesday night and veer
northwest, then increase to 10-15KT with gusts up to 25KT Wednesday
afternoon.

&&

.MARINE...
Showers and a few thunderstorms are expected at times through
this evening as weak low pressure crosses. Some storms could
produce hail, gusty winds, or even a waterspout.

A strong cold front will approach Sunday, then cross Sunday
night. A line of gusty showers and thunderstorms is possible
Sunday night as the front crosses. Southerly winds will become
westerly during this time, with gusts outside of shower and
thunderstorm activity gusting 20-25 kts at times. Additional SCA
winds are possible from the west/northwest Monday into Monday
night with gusts in the 20-30 kt range.

SCA conditions are likely across all the waters Tuesday into
Wednesday evening as west to northwest winds gust up to 20-30 kt.

&&

.FIRE WEATHER...
Wetting rains are possible through Monday afternoon as several
weather systems cross the area. The fire weather concern for next
week will in part be determined by how much rain falls this weekend.
Breezy to windy conditions are likely across the entire area Monday
and Tuesday, with some elevated winds lingering into Wednesday.

Fire weather conditions on Monday should be mitigated by min RH of
35-40pct or higher, lingering showers, and upslope snow in the
Alleghenies. The main concern Monday is going to be from strong
southwest winds that gust to 35-45mph in the mountains, and 25-30mph
at the lower elevations. Elevated to critical fire conditions are
possible Tuesday and Wednesday as winds remain high, fuels dry out,
relative humidity decreases, and temperatures warm.

&&

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

&&

SYNOPSIS...CPB
NEAR TERM...CPB
SHORT TERM...CPB
LONG TERM...KRR
AVIATION...CPB/KRR
MARINE...CPB/KRR
FIRE WEATHER...KRR

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