901
FXUS61 KLWX 221948
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
248 PM EST Fri Nov 22 2024

.SYNOPSIS...
Chilly temperatures, accumulating mountain snow, and windy
conditions will continue through tonight as low pressure
meanders across the northern Mid-Atlantic region. The upper-
level low will kick off the New England coast and toward the
Canadian Maritimes Saturday allowing high pressure to briefly
return for the latter half of the weekend. Another front will
push through the region Monday with high pressure Tuesday into
Wednesday. A more potent front and low pressure system will
arrive for the Thanksgiving holiday period.

&&

.NEAR TERM /THROUGH TONIGHT/...
A Blizzard Warning remains in effect for western Grant and
western Pendleton Counties due to persistent visibility to or
below 1/4 mile, frequent wind gusts of 35+ mph, and heavy
falling and blowing snow. Travel will be very difficult to
impossible in these areas. Near blizzard conditions are possible
over Garrett County MD and northwestern Highland County VA.

Otherwise, Winter Storm Warnings remain in effect across the
Allegheny Front, with Winter Weather Advisories for western
Mineral/extreme western Allegany Counties through tonight.
Accumulating upslope snow will lead to continued travel
disruptions, especially along the I-68 and US-219 corridors.

Upper-level low pressure will continue to meander around the
northern Mid-Atlantic this evening before slowly kicking toward
the New England coast late tonight into early Saturday morning.

The steadiest and heaviest upslope mountain snow shower activity
will continue through the evening hours. This is due to the
strongest piece of shortwave energy pivoting through as the
cutoff upper low progresses north and east toward New England.
Latest guidance and observations continue to advertise snowfall
rates of 1-2"/hr with persistent banding/squalls working over
the warning/advisory areas.

Outside of the significant snow accumulations, blowing and drifting
will be a problem. Brief whiteout conditions are expected at times
over the warning and advisory locations as winds remain elevated
tonight. Gusts up to 50 mph are likely over the higher ridges
with 30 to 40 mph gusts in the high valley floors below. This
will yield wind chills in the teens and 20s across the mountains.

Later tonight, moisture becomes shallower. This will halt ice
crystal formation, likely resulting in a period of freezing rain
or freezing drizzle especially above 3000 feet elevation.

East of the Appalachians, wind gusts of 25 to 35 mph are expected
through tonight. Wind Advisories are in effect for the crest of
the Blue Ridge Mountains. Precipitation should slowly diminish
this evening as the aforementioned shortwave pivots away.

Lows tonight will be in the 30s and 40s.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Precipitation over the Alleghenies will begin to decrease
Saturday morning into Saturday midday as the shortwave trough
kicks east and the upper-level low exits off coastal New
England. Freezing rain or drizzle may linger over the ridgetops
of the Allegheny Front, but it remains to be seen just how much
low-level moisture is left.

By Saturday afternoon, surface high pressure will slide in from
the Tennessee River Valley and central Appalachians allowing
conditions to slowly improve.

With incoming high pressure to the south and a departing
shortwave/upper-level low pressure system to the northeast,
expect windy conditions to continue. Sustained northwesterly
winds of around 20 to 30 mph are expected, with gusts up to 40
mph (mainly on the ridges).

Temperatures will warm back above freezing in the mountains
Saturday with upper 40s and low to mid 50s further east toward
the metro areas. Lows Saturday night will fall back into the mid
to upper 30s outside the mountains. High pressure will briefly
return to the area Sunday before pushing off the southeast U.S
coast Monday. Dry conditions are expected as a result along with
moderating temperatures. Highs Sunday will push into the low to
mid 50s with 40s over the mountains. Lows Sunday night will
fall into 30s.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Dry conditions are expected on Monday ahead of the next low
pressure system, which will push through late Monday night into
Tuesday. High temperatures will be well above average, reaching the
low to mid 60s (50s in the mountains). Mostly sunny skies to start
will give way to mostly cloudy skies by the late afternoon/evening
ahead of the approaching low.

Low pressure over the central U.S will track north and east into the
Great Lakes late Monday into Tuesday. This may bring some showers to
the region during this time along with a cooldown into Wednesday as
high pressure builds to our north. High temperatures on Tuesday
reach the upper 50s to low 60s (mid 40s to mid 50s in the mountains).

As high pressure settles to our north on Wednesday, highs drop into
the low 50s (upper 30s to low 40s in the mountains). While our region
largely remains within zonal upper-level flow Wednesday, a fast-
moving trough will begin to traverse the central CONUS into the TN
River Valley. The surface low associated with this system will
be somewhere over the TN River Valley late Wednesday.

Low pressure will then likely track near/south of our region
into Thanksgiving Day. The aforementioned high pressure to our
north may still be funneling in enough cold air for some wintry
precipitation in the Potomac Highlands. Further east, there are
still lots of questions at this stage in the forecast, and
nothing is certain yet. There has been a warmer trend over
recent model runs, favoring a rain event for most. However,
there are still a few solutions that bring wintry precipitation
further east. So, still need to watch this forecast in the
coming days for any potential swings one way or another.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Prevailing VFR conditions are expected at most terminals
through Sunday. Some brief periods of MVFR are possible through
late evening as a potent piece of upper-level energy pivots
through. Brief IFR is possible at KBWI/KMTN. Precipitation,
mainly in the form of rain, should gradually wind down between
00Z-03Z (7pm-10pm).

Wind will likely be the biggest impact to aviation through
Saturday. Expect sustained speeds of 10 to 20 kts with gusts 20
to 30 kts (peaking each afternoon/evening). Some LLWS is
possible near KCHO overnight and boundary layer winds attempt to
become a bit lighter. West to northwest winds will then decrease
slowly through Sunday with gusts running 15 to 20 kts.

Winds on Monday will taper off and turn southerly around 6 to 12
kts with continued VFR conditions. By Monday night, some
showers make their way into the region, which could lead to some
CIG/VSBY restrictions at times. Additionally, winds will
increase out of the south ahead of the cold front approaching
from the west. Once the front clears early on Tuesday, winds
will pick up sharply out of the W/NW. Expect wind gusts in the
20 to 25 kt range Tuesday afternoon.

&&

.MARINE...
High end SCAs are expected to continue through Saturday night with
frequent gusts of 20 to 30 kts expected across all waters. Gale
force gusts are expected over the open waters of the Chesapeake
Bay and lower tidal Potomac River through Saturday morning as
winds surge behind a departing shortwave trough. Winds will be
slow to taper Sunday with SCAs likely to continue across most
of the waters with gusts up to 20 kts.

Winds then turn out of the south on Monday as high pressure moves
quickly offshore. Winds may channel up the Chesapeake Bay and result
in SCAs over the wider waters. A line of gusty showers may push
through late Monday night into Tuesday morning along a cold
front. SCAs will likely be out, but could see a few gusts near
gale force. Don`t think it is a widespread event at this time,
but something to monitor.

Once the front clears early on Tuesday, winds will pick up sharply
out of the W/NW. Expect wind gusts in the 20 to 25 kt range
Tuesday afternoon, which will likely necessitate SCAs.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Winter Storm Warning until 3 AM EST Saturday for MDZ001.
     Winter Weather Advisory until 6 PM EST this evening for MDZ501.
VA...Wind Advisory until 6 AM EST Saturday for VAZ503-504-507-508.
     Winter Storm Warning until 6 AM EST Saturday for VAZ503.
WV...Winter Weather Advisory until 6 PM EST this evening for WVZ503.
     Wind Advisory until 6 AM EST Saturday for WVZ506.
     Blizzard Warning until 6 AM EST Saturday for WVZ501-505.
MARINE...Small Craft Advisory until 7 PM EST Saturday for ANZ530-535-
     536-538.
     Small Craft Advisory until 4 PM EST this afternoon for
     ANZ531>534-537-539>543.
     Small Craft Advisory from 7 AM to 7 PM EST Saturday for
     ANZ531>534-537-539>543.
     Gale Warning until 7 AM EST Saturday for ANZ531>534-537-
     539>543.

&&

$$

SYNOPSIS...DHOF/EST
NEAR TERM...DHOF/EST
SHORT TERM...DHOF/EST
LONG TERM...CJL
AVIATION...DHOF/CJL/EST
MARINE...DHOF/CJL/EST