Area Forecast Discussion
Issued by NWS Sterling, VA

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FXUS61 KLWX 140736
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
336 AM EDT Thu Mar 14 2024

.SYNOPSIS...
High pressure will slide offshore today with a low pressure system
approaching from the Ohio Valley. Well above normal temperatures and
dry conditions will persist through today before rain and a few
thunderstorms impacts the area on Friday. A secondary weaker system
may impact the region Sunday into Monday. A cooler airmass is
expected through much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The high pressure situated across the southeast will continue
to nudge further offshore throughout the day today. Flow becomes
more southwesterly today, which should allow highs to rise into
the mid 70s to near 80 despite a mix of sun and clouds
throughout the afternoon and evening. Mostly dry conditions are
expected for the daytime hours today.

The approaching center of low pressure will be nearing the Great
Lakes tonight with an associated warm front draped across portions
of PA. This will likely lead to well above average overnight
lows tonight with widespread 50s expected. Light rain may begin
to approach the Alleghenies and along the MD/PA border late
tonight, mainly after midnight. Most of the rain is expected to
hold off until daybreak on Friday.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
By Friday, the low pressure system will continue to track further
east across New England. The associated cold front will drop
southeast into the area during the day on Friday, with areal
coverage of rain increasing across the region. This system continues
to not impress in terms of QPF across the area, with less than a
quarter of an inch expected across most locations. Having said that,
with some minor instability around coupled with 40 knots of bulk
shear, cannot rule out the chance for a few isolated thunderstorms
ahead of the cold front. Any thunderstorms that do develop may
produce a quick 0.10-0.25" of rain during a shorter period of time.
Flooding concerns remain low with this system. Highs on Friday may
be a degree or two lower than today given the increased cloud
coverage and flow direction but it will still be well above normal
for this time of year. The cold front likely pushes through the area
by Friday night, bringing a cooler airmass with lows in the mid 30s
for the mountains to 40s for the lower elevations.

Some brief ridging will influence the area on Saturday with highs
about 10 to 15 degrees cooler than Thursday and Friday. This is
still 5 to 10 degrees warmer than average for this time of year.
Northwest winds early in the day will soon turn more
west/southwesterly for the afternoon and evening hours. Overnight
lows on Saturday will drop down into the 40s across most of the
area.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
A rex block persists across western North America
while the northern stream amplifies across the central/eastern U.S.
This particular configuration largely holds on through the early
portions of next week. Within the longwave trough extending up into
much of central to eastern Canada, a series of embedded disturbances
will track from the Upper Midwest toward the northeastern states.
One of these more formidable shortwaves is primed to push toward the
local area late Sunday into Monday. This carries a reinforcing cold
front through the area resulting in a pronounced drop in
temperatures. While Sunday yields high temperatures in the upper 50s
to mid 60s, the new work week will bring near to below normal
temperatures. For Monday and Tuesday, forecast highs range from the
mid 40s to low 50s, with low temperatures in the mid 20s to low 30s.
For mountain locales, expect these readings to be around 10 to 15
degrees colder, especially during the daytime. Ensembles do show
some gradual moderation by mid-week as heights slowly rise.

Looking at the precipitation and wind forecasts, some uptick in wind
fields are likely on Sunday in response to a frontal passage. The
more notable cool down ensues with a trailing system which quickly
lowers 1000-500 mb thicknesses on Monday. The cold advection will
lead to a brisk northwesterly wind with gusts up to 25 to 35 mph,
locally up to 40 to 45 mph in the mountains. Expect such winds to
persist into Tuesday as well given the tight cyclonic gradients
overhead. Besides the wind, upslope snow showers are possible along
the Allegheny Front. It is difficult to say how much snow will fall
as this will depend on moisture availability, the 0-3 km wind speed
and direction, and strength of the upper forcing. What appears to be
less of an issue are the temperatures given the cold air mass
settling in. Any precipitation is likely relegated to the higher
terrain with drier conditions downstream.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
VFR conditions are expected through the day today with light,
variable winds in place. A better mix of mid to high level clouds
will push through during the day. Sub-VFR conditions return during
the day on Friday as a cold front approaches the area. Cannot rule
out a brief thunderstorm for the terminals during the afternoon
hours but confidence is low at this time.

VFR conditions return on Saturday but winds will be elevated out of
the WNW 15 to 20 knots before turning more westerly/southwesterly
later in the day.

VFR conditions are expected on Sunday and Monday across the area
terminals. Some snow showers enter the picture on Monday, but these
remain along the Allegheny mountain chain. The big story will be the
increasing winds as a series of cold fronts push through the area.
Wind start to back to northwesterly on Sunday as the first boundary
moves through. Gusts up to 20 to perhaps 25 knots are possible,
especially during the afternoon. A stronger cold front arrives on
Monday with northwesterly gusts increasing to around 25 to 30 knots.

&&

.MARINE...
Light, variable winds are expected today with high pressure off to
the south moving further offshore. Low pressure system approaches
the Great Lakes tonight, with winds increasing late tonight into
Friday. SCAs may be needed starting late tonight and into Friday but
confidence is low given the warmer air over cooler waters producing
low level stability. Showers and isolated thunderstorms may impact
the waters during the day on Friday before pushing further offshore
by Friday night. SCA winds are possible just behind the front for a
6 to 8 hour period. These winds will likely diminish heading into
early Saturday as upper ridging builds in across the area.

Initial southwesterlies give way to west-northwesterlies the second
half of Sunday. This is in response to the initial cold frontal
passage. This could bring near-advisory caliber winds to portions of
the waterways. A better chance for Small Craft Advisories loom on
Monday into Monday night as the stronger frontal system presses
through. Northwesterly gusts range from 20 to 30 knots, with these
higher bounds over the southern waters.

&&

.FIRE WEATHER...
Today will be warmer, with only slight increases in Min RH to 25 to
35 percent. Winds will become more southerly with gusts increasing
during the evening along the higher elevations.

A low pressure system will approach the area Friday and bring the
next chance of rain, although forecast amounts have been trending
downward.

&&

.TIDES/COASTAL FLOODING...
Anomalies will continue to increase through the end of the week as
winds begin to increase out of the south. Some tidal sites may reach
minor flood stage later today and again on Friday ahead of the next
low pressure system expected to impact the area. The wind shift
behind the cold front Friday evening will alleviate temporary tidal
flooding concerns.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

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


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