Area Forecast Discussion Issued by NWS Sterling, VA
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000
FXUS61 KLWX 171833
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
233 PM EDT Sun Mar 17 2024
.SYNOPSIS...
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A couple of cold fronts will cross the area through Monday, then
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.-- End Changed Discussion --
&&
.NEAR TERM /THROUGH TONIGHT/...
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Stronger winds have mixed down along the eastern slopes of the
Alleghenies into the Shenandoah Valley, where gusts of 40-45mph have
been observed in Petersburg, Upper Tract, near Staunton, Afton,
Martinsburg, and along I-68 in western MD. This compressional
warming has also resulted in higher temps than forecast, with mid to
upper 60s. Similar winds are occurring atop and on the eastern
slopes of the Blue Ridge, with temps in the upper 60s to 70s east to
the Western Shore. Westerly wind gusts of 20-25mph east of the Blue
Ridge likely through sunset. Clouds have mostly dissipated, resulting in
mostly to partly sunny skies.
Colder air filters into the region tonight dropping temperatures to
near normal for mid-March. Some cloud cover will build back in
tonight. Overnight lows drop to or below freezing west of the Blue
Ridge, and in the mid to upper 30s to the east.-- End Changed Discussion --
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.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
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Another cold front crosses the area on Monday, bringing another
increase in west-northwest winds Monday afternoon. The FROPA itself
will be dry, though mountain snow showers are expected behind the
front Monday evening into Tuesday. Recent model trends have
increased QPF in the Alleghenies as favorable dynamics support
higher snow totals. The forecast has been upped to 1-3 inches of
snow, with most of that expected above 2500ft.
Cooler temperatures Monday afternoon in the 40s west of US-15, and
the low to mid 50s to the east. Winds gust around 20-30mph through
late afternoon, with higher gusts possible in the mountains.
Temperatures over most of the area drop to or below freezing Monday
night. The cooler temps continues into Tuesday, with another burst
of mountain snow showers possible Tuesday night. Given several days
of dry, breezy conditions, the potential for rapid fire spread may
increase as the week progresses (see the Fire Weather section
below).-- End Changed Discussion --
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.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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The synoptic pattern will be more zonal by Wednesday, but maintains
broad troughing over the eastern CONUS and a closed low over the
southwest US. A modest wave may bring a burst of snow to the
Alleghenies Tuesday night/early Wednesday morning, then high
pressure builds in from the southwest.
Gusty winds continue into Wednesday with the passage of a dry
reinforcing cold front. The strongest winds during this period are
expected to gust 25-35 mph and up to around 40-45 mph in the higher
elevations along the Allegheny Front. Winds gradually decrease
through Thursday afternoon.
Temperatures will be mild on Wednesday before dropping behind the
cold front Wednesday night. The pattern becomes less certain towards
the end of the week. Guidance has come into better agreement on a
low passing through the Southeast and developing offshore, but
models diverge timing and how far north it tracks towards our area.
Regardless, it seems the next shot for precipitation for the area
comes Friday or into the weekend.-- End Changed Discussion --
&&
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
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VFR conditions are expected through Tuesday night. A series of cold
fronts will cross the area in that time. While they won`t bring any
precip east of the Alleghenies, expect increasing west to northwest
wind gusts each afternoon. Peak gusts around 25-30kt expected, with
some occasional higher gusts possible. CIGs remain well above VFR
due to high mixing heights each afternoon.
VFR conditions are expected Wednesday and Thursday with any possible
precipitation early Wednesday morning limited to the Alleghenies and
as such not expected to impact the terminals. The main concern will
be gusty W/NW winds 25 to 30 kts on Wednesday.-- End Changed Discussion --
&&
.MARINE...
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A series of cold fronts will cross the waters over the next few
days, bringing gusty west to northwest winds to all the waters.
Small Craft Advisories are in effect, and likely to be needed
Tuesday and Wednesday. The strongest gusts are expected Monday
evening into Tuesday morning, where near-gale gusts possible over
the open waters of the Chesapeake Bay.
Gusty and northwesterly winds are expected on Wednesday as a dry
reinforcing cold front passes through and low pressure departs to
the northeast. SCA conditions are likely over portions of the waters
Wednesday and all waters for the first half of Thursday.-- End Changed Discussion --
&&
.FIRE WEATHER...
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Gusty conditions along the eastern slopes of most mountains this
afternoon, with westerly gusts of 40-45mph due to downsloping winds.
To the east of the Blue Ridge and in the Shenandoah Valley, minimum
relative humidity values between 20-25pct this afternoon. Gusts to
25-30mph expected in most other areas. This will produce very good
to excellent smoke dispersion today.
Looking at the week ahead, minimum RH values 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.-- End Changed Discussion --
&&
.TIDES/COASTAL FLOODING...
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Tidal anomalies reach their peak this afternoon as Annapolis,
Straits Point, and SW DC Waterfront all reached Minor Flood stage.
Many other sites reached Action Stage. Winds have now shifted to
west/northwest behind a weak cold front that crossed the area. This
is going to help bring tidal anomalies down over the next few days.
No tidal flooding is currently anticipated, though sensitive sites
at Annapolis, Straits Point, and DC SW Waterfront could reach Action
Stage during high tide this evening.-- End Changed Discussion --
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...Coastal Flood Advisory until 5 PM EDT this afternoon for
DCZ001.
MD...Coastal Flood Advisory until 4 PM EDT this afternoon for
MDZ014.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for
ANZ530>543.
Small Craft Advisory from 9 AM to 6 PM EDT Monday for ANZ530-
535-536-538-542.
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.-- End Changed Discussion --
&&
$$
SYNOPSIS...KRR
NEAR TERM...KRR
SHORT TERM...KRR
LONG TERM...CAS
AVIATION...KRR/CAS
MARINE...KRR/CAS
FIRE WEATHER...KRR
TIDES/COASTAL FLOODING...KRR