Forecast Discussion
042
FXUS61 KLWX 211519
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1019 AM EST Sat Dec 21 2024
.SYNOPSIS...
Lingering snow showers in the Alleghenies, with some flurries
possible east of the mountains today. Strong Canadian high pressure
builds in through Monday, with dry and very cold conditions.
Precipitation chances increase as another front approaches during
the middle of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Have already seen a corridor of snow showers across north
central Maryland this morning that resulted in some localized
minor accumulations, and other lighter snow showers and flurries
elsewhere. Expect activity to continue to make it over the
mountains today with Froude numbers well over 1. Current radar
suggest Garrett County into the northern Potomac Highlands will
have the best opportunity for accumulating snow bands with
streamers currently aligned off Lake Erie into southwest PA. The
prospects for squalls or heavier snow bands east of the
mountains seem to be limited by low moisture and instability and
the fact that the best PVA is lifting northeast of the area.
Flurries are definitely in the cards though, and will monitor
radar trends through the rest of the day. The risk for snow will
be diminishing with sunset.
Temperatures tracked a little higher overnight into this morning
than progged, so ultimately values should hold fairly steady
into the afternoon.
Previous discussion:
Reinforcing upper troughing continues across the Mid-Atlantic today
as a strong Canadian high begins to build south into the region.
Mountain snow showers continue through the afternoon, with some
periods of heavier showers likely at times. These streamers will
result in some isolated areas picking up higher snow totals. Snow
totals range from 1-3", with up to 4" possible in some areas that
repeated streamers/heavier snow showers.
Aside from snow, it will be downright cold as blustery conditions
develop this morning into this evening. Winds gust around 25-35 mph,
with up to 40 mph in the mountains. Combined with highs in the 30s,
the resulting wind chill values during the middle of the day are
likely to be in the teens to 20s, with single digits in the
mountains. Brisk to blustery conditions continue tonight, as lows
drop to the mid to upper teens. The result is wind chills in the
single digits to low teens, with below 0 values in the Alleghenies.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Strong Canadian High continues its march across the Eastern U.S.
through the start of next week. Well below normal temperatures
Sunday as high struggle to reach freezing, and lingering wind gusts
of 15-20 mph make for a very cold afternoon. Sunday night brings
lows in the single digits to lower teens for most. Monday is not
quite as cold, though still below normal with highs in the 30s.
Clouds build in throughout the day as a weak clipper approaches from
the northwest. This could bring some snow shower to the Alleghenies
and along/north of I-70 late Monday night.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
A cold front, associated with a low pressure system tracking to our
north, will bring a chance to slight chance of a rain/snow mix as it
moves through the forecast area on Tuesday. Highest precipitation
chances are along and west of the Alleghenies with mountain snow
showers expected throughout the day. Those along the I-81 corridor
and south of I-66 will likely stay dry throughout the day.
Conditions dry out overnight areawide with precipitation chances
returning Wednesday afternoon as the frontal boundary remains
nearby. Overall, PoPs remain low (near or below 30%) through Friday
with moderating temperatures leading to rain being the primary
precipitation type should showers occur. As temperatures fall
Thursday night, brief snow showers are possible at higher
elevations.
Temperatures moderate throughout the long term period with
temperatures slowly rising each day. High temperatures will be in
the 30s and 40s each day with overnight lows in the 20s and 30s.
&&
.AVIATION /15Z SATURDAY THROUGH WEDNESDAY/...
Snow showers split DCA and BWI earlier, but not confident in any
additional activity through the day unless it`s flurries, so no
TAF changes at this time. Highest chance for snow showers
remains at MRB.
Otherwise, VFR conditions expected through Monday as a strong
Canadian high builds across the region. The main aviation impact
today is going to be from strong Northwest wind gusts. Winds
begin to increase early this morning, then peak late morning to
early afternoon with gusts around 25-30 knots. Winds slowly
diminish tonight into Sunday. A few flurries or light snow
showers are possible at MRB today, though confidence in where
these could occur is too low to include in TAF at this time.
Some flurries possible at other terminals too.
Sub-VFR conditions are possible Tuesday and Wednesday as a frontal
boundary moves through the forecast area. Light and variable winds
are expected both days.
&&
.MARINE...
Hazardous marine conditions expected today as a strong Canadian
high pressure builds across the region. Peak wind gusts will be
around 25-30 knots across the waters, with occasional gusts
near gale-force possible in the open Chesapeake Bay waters.
Winds slowly diminish this evening, but remain in SCA levels
through Sunday afternoon. Winds are forecast to fall below 10
knots Sunday night into Monday.
Winds are expected to stay below SCA criteria Tuesday and Wednesday.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 10 AM EST Sunday for
ANZ530>532-536- 538>540-542. Small Craft Advisory until 4 PM EST
Sunday for ANZ533-534-537- 541-543. Small Craft Advisory until
9 PM EST this evening for ANZ535.
&&
$$
SYNOPSIS...KRR
NEAR TERM...ADS/KRR
SHORT TERM...KRR
LONG TERM...AVS
AVIATION...ADS/AVS/KRR
MARINE...ADS/AVS/KRR
