Forecast Discussion for Willowsford Farm and vicinity from the NWS in Sterling, Virginia

FXUS61 KLWX 231344

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
944 AM EDT Wed Sep 23 2020

High pressure will weaken and move south of the area through
tonight, then move offshore Thursday into Friday. The remnants
of Beta will likely pass to the south while weakening Friday
into Saturday. A couple cold fronts are expected to approach
from the Great Lakes and Ohio River Valley late in the weekend
into early next week.


High pressure centered over the southern Appalachian Mountains
will will slide eastward into the western Atlantic Ocean by
Thursday morning. Winds will be westerly and warm advection
should prevail. Smoke aloft may reduce insolation, but the smoke
is very thin (and thinning further). Warming should be adequate
to allow temps to reach around 80 in much of the region. Lows
tonight will remain mild, with 50s common.


High pressure will continue sliding east into the Atlantic
Thursday. Temps will remain warm, but with a bit more cloud
cover as Beta approaches, they may be a little lower than today.
Lows Thursday night likely remain mild, with 50s common.

Things are looking a bit less pleasant for the end of the work
week. While many models continue to keep the rain from Beta`s
remnants mostly south of the region, it is notable that the
ECMWF has crept northward significantly, bringing steady rain
across the CWA later Friday into Friday evening. Therefore, have
added some chance pops up to the I-95 corridor Friday into
Friday night, with slight chance pops further northwest. Highs
Friday will depend greatly on how far north the rain gets, with
a wetter solution likely being cooler than our forecast of
upper 70s. Will continue to monitor.


By early Saturday, the remnants of of Beta will likely be
moving offshore, as guidance seems to be trending a little bit
earlier over the past few model runs. High pressure will located
over the western Atlantic, leading to a southerly flow over the
region at the low-levels. This will lead to a continued surge
of moisture into the region, and continued shower chances. Will
be lowering POPs on Saturday though, as the main feature will
have moved offshore pretty early in the day. Highs on Saturday
will reach the upper 70s to near 80, with dew points in the mid
60s. So, it will also feel a little more humid as well.

Sunday into early next week remains somewhat uncertain in
regards to the exact timing of the next two weather features.
There will be 2 cold front passages between Sunday and early
Wednesday. The first looks to be late Sunday, as a shortwave
passes by to our north through the Great Lakes and into the
northeast. Still going to maintain the current forecast for POPs
and thunder on Sunday, but do think that the best upper-level
energy could be just to our north. Some guidance keeps us mostly
dry in our forecast area, so still some uncertainty there. For
Monday and Tuesday, a much stronger shortwave will move out of
central Canada into the northern Plains and then over the Great
Lakes by late Tuesday. This will drag a much stronger cold front
through the area sometime late Tuesday. Between these two
features, expect a lull in activity, so will likely come down a
little on POPs for Monday afternoon and early Tuesday. Temps
will gradually be on the decrease through Tuesday, with highs
dropping into the low to mid 70s by Tuesday.

Cooler air will arrive in the wake of this frontal boundary by
mid-late week, as a deep trough builds over the eastern CONUS.


VFR at all TAF terminals through Thursday night as high pressure
lingers over the region, with winds shifting from westerly to
southerly and then southeasterly. Sub-VFR possible Friday and
Friday night as the remnants of Beta pass just to the south,
possibly spreading rain northward into the region, with KCHO
most susceptible to degradations.

Showers associated with the remnants of Beta will be moving
offshore early Saturday, so VFR conditions should prevail for
much of the day. A weak cold front then pushes through on
Sunday, bringing a chance for showers, and perhaps an isolated
thunderstorm. Still some uncertainty on precipitation potential
with this front, but some restrictions are possible with the
frontal passage late Sunday.


High pressure pushing south of the waters should allow flow to
relax through Thursday. Southerly to easterly flow may briefly
intensify later Thursday into Friday as the remnants of Beta
approach from the southwest. It remains unclear as to whether
gusts may reach SCA criteria as Beta passes.

Could see some gusty winds early Saturday as Beta exits off the
east coast, but looks to most likely stay below SCA criteria.
This will continue throughout the day on Saturday and Sunday, as
high pressure sits over the western Atlantic and a cold front
approaches from the west on Sunday, leading to continued
southerly flow.


Widespread anomalies of around 1 foot remain across the tidal
waters at this time. This will bring many sites to action stage
at least through today, with the most sensitive sites possibly
reaching minor again on the late day high tide. The early high
tide is the lower of the two astronomically, and is not
expected to reach minor at any locale.

Anomalies may be slow to drop over the next few days as flow
will weaken and a significant push of water out of the bay may
be difficult to come by.


The KLWX (Sterling, VA) WSR-88D remains out of service until further
notice. The outage is due to a failure within the Radar Data
Acquisition Functional Area that occurred early in the morning on
September 20, 2020.

Technicians from the National Weather Service Radar Operations
Center will arrive in Sterling on Saturday, September 26, to
diagnose the failure. At that time, they will determine the full
scope of the failure, and work with WFO Sterling electronics program
staff in taking subsequent maintenance actions. Action and diagnosis
includes repairing the gear box and assessing the health of the bull-

Users of KLWX can utilize adjacent weather radars located in Dover
DE (KDOX), Mt. Holly NJ (KDIX), Pittsburgh PA (KPBZ), Charleston WV
(KRLX), Blacksburg VA (KFCX), and Wakefield VA (KAKQ).





NWS LWX Office Area Forecast Discussion