Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 170749
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
349 AM EDT Sun Mar 17 2024

.SYNOPSIS...
A cold front will cross the area today, then a secondary front
will cross the region Monday as high pressure gradually builds
in from the Midwest. A third cold front will cross the region
Wednesday. High pressure will build to the north through the end
of the week as low pressure takes shape to the south.

&&

.NEAR TERM /THROUGH TONIGHT/...
Abundant clouds and a few showers accompanied a cold front over
the Ohio Valley early this morning, approaching the Alleghenies.
Westerly flow should keep shower activity limited to along and
west of the Allegheny Front, though shallow moisture may result
in clouds or perhaps a sprinkle east of there as the cold front
crosses the region. Westerly breezes will gust 20 to 30 mph for
most, slightly higher at higher elevations. This will lead to
above normal temperatures given the downslope component.

Colder air filters into the region tonight dropping temperatures
to near normal for mid-March. Clouds should try to dissipate,
but with some thin layers of moisture trapped in the column,
some wave clouds are possible from time to time amid westerly
breezes.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
Another cold front looks to cross the region Monday. This front
will be largely moisture-starved with continued downslope flow
east of the mountains. However, increasing mid-level moisture
coupled with a bit of instability accompanying the associated
mid/upper wave could result in a few sprinkles or flurries east
of the Alleghenies. Along and west of the Allegheny Front,
periods of snow showers are possible with generally light (sub-
advisory accumulations) anticipated. Temperatures tumble to a
few degrees below normal, feeling colder due to winds gusting
upwards of 30 mph during the day.

The cooler trend continues through Tuesday with episodic
mountain snow showers possible as weak waves cross. Given
several days of dry, breezy conditions, the potential for rapid
fire spread may increase (see the Fire Weather section below).

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
During the middle of the week, the longwave trough encompassing the
the Upper Midwest out to the Eastern Seaboard will begin to relax as
heights begin to rise. This results in a bit more zonal component to
the mid/upper wind fields. At this occurs, a stalled upper low
across the Desert Southwest will make its way eastward to the Four
Corners region. All model solutions agree on carrying the associated
shortwave energy toward the southern U.S. during subsequent days.
Where they begin to vary is with the strength of the trough itself
as well as how much latitude it will gain in time. Determining the
answers to these questions should eventually provide the level of
impacts to the Mid-Atlantic region.

As this entire pattern unfolds, a cold front pushes across the area
early Wednesday. While a few residual upslope snow showers are
possible along the Alleghenies, this frontal boundary will likely be
a dry one. The guidance does support another hefty wind field
overspreading the region. Near advisory criteria wind gusts are
possible over the Allegheny Front. Off to the east, west-
northwesterly gusts could push up to 30 to 35 mph. This will be
accompanied by mostly sunny skies along with low humidity levels.
Given the multi-day period of dry gusty winds, further drying of the
vegetation (i.e., fuels) may increase fire weather concerns over the
area. Although winds slacken a bit into Thursday, relative humidity
values in the 20 to 30 percent range would further enhance the
mentioned fire weather issues. On the temperature side, expect
cooler temperatures into Thursday and Friday. After mid-week highs
in the mid 50s to low 60s, the forecast carries such temperatures
back down into the mid 40s to mid 50s (cooler in the mountains).

A modest increase in rain chances is evident in the forecast package
by as early as Friday morning. Depending on precipitation timing, it
may even start as a wintry mix over the higher elevations.
Otherwise, expect a chance of rain each day heading into next
weekend. Deterministic models are all over the board so it may take
some time to resolve the details of this system.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
The main story over the next few days will be afternoon wind
gusts of 20 to perhaps 30 kts out of the W/NW. Prior to these
gusts reaching the surface, LLWS is likely until about 12z-13z
this morning given light SSW surface winds, and WSW winds of
30-40 kts at 2-3 kft AGL.

Otherwise, VFR conditions are forecast at the TAF sites through
Tuesday night, though some patchy MVFR CIGs in mountain wave
clouds/stratocumulus can`t be ruled out near KMRB this morning
and again early Monday morning. A stray sprinkle or flurry also
can`t be ruled out Monday or Tuesday, but chances for any
restrictions look very minimal.

For Wednesday and Thursday, the area terminals can expect VFR
conditions with the big issue being the gusty winds. A reinforcing
cold front pushes through early Wednesday leading to another round
of breezy west-northwesterly winds. Gusts up to 25 knots are
possible on Wednesday afternoon with a bit of a drop off into the
night. By Thursday, winds back further to more of a northerly
direction as gusts drop to the 15 to 20 knot range.

&&

.MARINE...
Blustery W/NW winds are expected much of the time through early
this week. The strongest winds are most likely late Monday into
early Tuesday when a few gale-force gusts are possible. Dry
conditions are expected. Frequent gusts of 25-30 kts are most
likely otherwise.

In the wake of another cold front, winds pick up in earnest across
the local waterways. West-northwesterly gusts increase to around 20
to 25 knots on Wednesday into the night. Most spots will require
Small Craft Advisories during this period. Winds shift to the north-
northwesterly direction by Thursday with advisory caliber gusts
through the afternoon hours. There may be some drop off during the
evening before ramping back up again by Thursday night.

&&

.FIRE WEATHER...
East of the Alleghenies, minimum relative humidity values are
expected to drop to 20 to 35 percent each afternoon through
Thursday. Generally poor relative humidity recovery to 50 to 60
percent is anticipated each night. These dry conditions will be
accompanied by westerly to northwesterly winds of 15 to 20 mph
with gusts to around 30 mph at times, especially during the
afternoon hours each day. Higher gusts around 40 mph are
possible over the higher elevations at times.

Scattered to broken high clouds and stratocumulus are possible
at times. Mixing and smoke dispersion are expected to be good
to excellent much of the week. The next chance of wetting rain
comes with approaching low pressure on Friday.

&&

.TIDES/COASTAL FLOODING...
Ahead of the next cold front arriving later this morning, tidal
anomalies have really begun to pick up over the local area. Such
anomalies currently run between 1.50 to 2.00 feet which would carry
many locations into the Action stage. However, the more sensitive
locations like Annapolis and Strait`s Point could see minor tidal
flooding with the morning high tide. As such, Coastal Flood
Advisories have been issued. Will continue to monitor the threat at
D.C. Southwest Waterfront.

Thereafter, a shift to northwesterly flow will usher much of the
elevated water levels back toward the south and east. Thus, do not
expect any tidal flooding concerns during subsequent days.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory from 9 AM this morning to 4 PM EDT this
     afternoon for MDZ014.
     Coastal Flood Advisory until 11 AM EDT this morning for MDZ017.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 10 AM this morning to 6 PM EDT this
     evening for ANZ530-535-536-538-542.
     Small Craft Advisory from 9 AM to 6 PM EDT Monday for ANZ530-
     535-536-538-542.
     Small Craft Advisory until 6 PM EDT this evening for
     ANZ531>534-537-539>541-543.
     Small Craft Advisory from 10 PM this evening to 6 PM EDT
     Monday for ANZ531>533-539>541.
     Small Craft Advisory from 1 AM to 6 PM EDT Monday for ANZ534-
     537-543.

&&

$$

SYNOPSIS...DHOF
NEAR TERM...DHOF
SHORT TERM...DHOF
LONG TERM...BRO
AVIATION...BRO/DHOF
MARINE...BRO/DHOF
FIRE WEATHER...DHOF
TIDES/COASTAL FLOODING...BRO


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