Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 190801
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
401 AM EDT Tue Mar 19 2024

.SYNOPSIS...

Gusty winds and low relative humidity values look to continue
through Thursday as a result of strong low pressure over eastern
Canada and broad high pressure building south from the northern
Plains region. A cold front will push through the area late tonight
into Wednesday bringing another round of accumulating upslope
mountain snow showers to the Alleghenies. More widespread
precipitation chances hold off until Friday and the start of the
weekend as an area of low pressure pushes north from the Gulf Coast
region.

&&

.NEAR TERM /THROUGH TONIGHT/...
Outside of some lingering mountain upslope snow showers over the
Alleghenies this morning expect another dry and breezy day ahead.
Deep low pressure will remained locked up over eastern Canada with
broad high pressure along the Gulf Coast and an even stronger high
pressure system building south from central Canada. This will lead
to a continuation of gusty west to west-southwest flow across the
region and low relative humidity values leading to increased fire
weather concerns (see Fire Weather discussion below). Highs today
will push into the upper 40s and low to mid 50s. Expect some mid-
level cloudiness especially later this afternoon and evening as
longwave troughing and an approaching cold front over the Ohio River
Valley advance toward the region.

Skies will clear back out overnight east of the Alleghenies with
westerly downslope flow. Areas along and west of the Alleghenies
will likely see continued cloudiness and another shot of
accumulating upslope mountain snow showers. An additional 1-2 inches
of snow is possible at elevations above 2500 feet. Lows will drop
into the mid to upper 30s and low 40s with values closer to freezing
over the mountains. Winds will also begin to increase with longwave
trough positioned nearby and the next incumbent shortwave
trough/front set to approach from the west Wednesday. With that
said, expect sustained west-west southwest winds gusting between 20-
25 mph east of the Blue Ridge and 25-35 mph gusts further west this
afternoon. Gusts of 40-50 mph remain possible along the eastern
slopes of the Alleghenies especially later this evening and into
Wednesday morning. This is especially tries across western MIneral,
western Allegany, western Grant, Pendleton, and Highland counties
where a fairly persistent signal for advisory criteria winds
continues to show up. Higher confidence for wind advisory criteria
appears to be toward Wednesday morning and afternoon. With that
said, have decided to hold off on wind headlines at this time.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
A reinforcing cold front and shortwave trough cross the area
Wednesday. The front will bring limited moisture in the form of
mountain upslope snow showers over the Allegheny Front and passing
clouds further east. The bigger story will be the winds with 850 mb
winds running 40-50 kts ahead of the boundary Wednesday morning and
it`s wake Wednesday afternoon. Sustained west to northwest gusts as
a result, will run between 20-30 mph east of the Blue Ridge with 30-
40 mph gusts further west. 40-50 mph gusts are likely especially
along the eastern slopes of the Alleghenies. Will need to monitor
the potential for wind headlines mainly over the mountains given the
consistent signal amongst the deterministic/ensemble guidance. These
strong winds could result in isolated downed trees and power lines.

With downsloping flow ahead and in the immediate wake of the
boundary expect slightly warmer temperatures Wednesday. Highs will
climb into the upper 50s and low 60s. The mild air combined with
gusty winds and lowering relative humidity/fuel moistures will lead
to additional fire weather concerns. A Fire Weather Watch remains in
effect from Wednesday morning into Wednesday evening for much of the
forecast area outside of western MD and north-central MD.

High pressure will build eastward from the Great Lakes region to
southern New England Thursday and Thursday night. Highs will be
cooler than average with temperatures in the lower to middle 40s
with some lower 50s in eastern Virginia. Low relative humidity
values will remain although winds will gradually decrease throughout
the day as the gradient relaxes. Lows Thursday night will fall into
the mid to upper 20s (low 20s mountains).

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...

Cutoff low pressure lifting from the Gulf to the Mid-Atlantic
later this week will spread rain across the area Fri night into
Saturday. Low pressure begins to pull out Sat night with rain
ending. Sfc ridging sets up over the first half of the week
keeping fair weather. Another system may impact the area next
Tue bringing the next chance of showers.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
VFR conditions are expected through Thursday with gusty winds of 20-
30 kts each afternoon. The strongest winds look to arrive Wednesday
into Wednesday afternoon as a cold front crosses the region. West to
northwest gusts will run between 30-35 kts west of KCHO and KMRB
with 25 to 30 kt gusts expected across the corridor terminals. The
front will come through dry with any precipitation in the
form of mountain snow showers confined to terminals west of KCBE.

Winds will gradually decrease Thursday night with VFR conditions
expected to continue. Sub-VFR conditions return Friday afternoon
into Saturday as an area of low pressure approaches from the Gulf
Coast states. Light rain will approach the terminals Friday
afternoon and evening and perhaps some fog Friday night. Winds north
becoming east 5 to 10 knots Thursday night. Winds southeast 10 to 15
knots gusts up to 20 knots Friday and Friday night.

Rain Fri night and Sat will likely cause some flight
restrictions.

&&

.MARINE...

A prolonged period of gusty west to northwest SCA level winds will
continue across all waters through midweek. Small craft advisories
remain in effect for all waters through tonight and will likely need
to be extended through Wednesday.

SCA level winds look to continue Thursday as brief high pressure
builds north of the region. Northwest winds will gusts 15 to 25 kts
before falling back below SCA levels Thursday night into Friday.
Rain chances return to the waters Friday as an area of low pressure
approaches from the Gulf Coast states. Additional SCA level winds
out of the south/southeast can be expected from this passing coastal
low pressure system Saturday into Sunday. Potential gales are also
possible over the open waters during this time.

Winds will be strong Sat night on the north side of the low and
will likely generate gale force winds.

&&

.FIRE WEATHER...

Elevated to high fire danger is expected to continue across the
region through Thursday as dry and gusty conditions persist. An
Elevated Fire Danger Statement has been issued for most of
Maryland, eastern West Virginia, and Virginia through this
evening to encompass the increased fire weather threat. Relative
humidity values are expected to drop back to around 15 to 25
percent this afternoon into early evening. West winds will gusts
15 to 20 mph in the valleys, and 20 to 25 mph on the eastern
slopes of the mountains. Gusts could occasionally be close to 30
mph. This will result in the continued drying of fine fuels.

The worst fire weather conditions are likely on Wednesday. A Fire
Weather Watch has been issued for all of our Virginia, and West
Virginia counties, plus the DC Metro. The Watch may need to be
expanded into most of Maryland pending coordination with state fire
partners. The strongest winds will be west of the Blue Ridge with
westerly gusts of 30-40mph. Slightly lower gusts are expected east
of the Blue Ridge at 25-30 mph. The wind combined with low relative
humidity values of 20 to 30 percent and 10/100 hr fuel moistures of
9-15 percent will yield for favorable conditions for the rapid
spread of wildfires. Additionally, Special Weather Statements will
be needed on Thursday, to account for continued elevated fire
weather conditions. Wind gusts Thursday will decrease throughout the
day running 15 to 25 mph.

The next chance for widespread wetting rain may come Friday.


&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Fire Weather Watch from Wednesday morning through Wednesday
     evening for DCZ001.
MD...Fire Weather Watch from Wednesday morning through Wednesday
     evening for MDZ013-016-503-504.
VA...Fire Weather Watch from Wednesday morning through Wednesday
     evening for VAZ025>031-036>040-050-051-053>057-501>508-
     526-527.
WV...Fire Weather Watch from Wednesday morning through Wednesday
     evening for WVZ050>053-055-501>506.
MARINE...Small Craft Advisory until 8 PM EDT this evening for
     ANZ530>533-535-536-538>542.
     Small Craft Advisory from 7 AM this morning to 8 PM EDT this
     evening for ANZ534-537-543.

&&

$$

SYNOPSIS...EST
NEAR TERM...EST
SHORT TERM...EST
LONG TERM...LFR
AVIATION...LFR/EST
MARINE...LFR/EST
FIRE WEATHER...EST


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