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

FXUS61 KLWX 250802

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
402 AM EDT Sun Oct 25 2020

A cold front will stall to the south through tonight before
returning north as a warm front Monday. Another cold front will
move into the area Tuesday and it will stall out nearby through
Friday. The remnants of Zeta and another low pressure may track
along the boundary, possibly impacting our area Wednesday night
through Friday. High pressure will likely return for next


A shortwave disturbance embedded within the southern stream
(currently located over the Deep South) will approach the area
from the southwest today. Isentropic ascent/warm advection atop
a cold air wedge in place at the surface has enabled rain to
develop well in advance of the shortwave. This rain is currently
spreading northward from central Virginia into the rest of the
forecast area. Periods of rain are expected through the day
today, with a gradual drying trend from southwest to northeast
through the late afternoon and evening hours. Overall, it will
be a very dreary day, with cooler air filtering in on north-
northeasterly flow, low cloud cover, and periods of rain.
Temperatures (primarily in the 50s as of 3 AM), will drop back
into the 40s as rain breaks out, and hold steady or potentially
even drop slightly through the day.

A few lingering showers may be possible overnight, especially
over northeastern Maryland, but widespread steady rainfall is
expected to end as the shortwave progresses overhead and then
eventually off to the northeast. However, low clouds will hold
strong, and areas of drizzle and fog will remain possible
through the night with the cold air wedge holding in place.
Temperatures will hold steady overnight in the 40s.


Broad southwesterly flow aloft will reside over eastern portions
of the CONUS on Monday. As the shortwave departs to the
northeast, and a positively tilted trough digs into the Desert
Southwest, heights aloft will rise slightly in response. This
may invoke just enough of a response at the surface to turn
winds southerly at the surface and eventually break up the cold
air wedge in place to the east of the Appalachians. Clouds
should gradually thin through the day, but it may take much of
the day for breaks of sun to develop, especially to the east of
the Blue Ridge. Temperatures will be dependent on how much
sunshine can break out, but as of now it looks like most
locations will top out in the mid 60s to near 70.

Moving toward Tuesday, the northern half of the large positively
tilted trough extending from Hudson Bay to the Four Corners
region will become more progressive, eventually leading to the
formation of a cutoff upper low over the Desert Southwest and a
more progressive zonal flow pattern within the northern stream.
As a shortwave embedded within the northern stream tracks to
our north on Tuesday, it will act to drive a weak cold front
southward into our area. A shower or two can`t be ruled out,
especially over northwestern portions of the forecast area, but
most locations are expected to remain dry since there will be
little to no mid- upper level support accompanying the frontal


A boundary will remain stalled nearby or over the area for
Wednesday along with a zonal flow aloft. A couple showers are
possible, but much of the time may turn out dry behind a
departing disturbance. Near seasonable temperatures are most
likely, but there is still some uncertainty because if the
position of the boundary fluctuates just a little (most likely
to set up near central VA at this point), that would have a
significant impact on temperature forecasts.

The remnants of Zeta are likely to get absorbed by the southern
stream of the jet, and this may track along the boundary
possibly impacting our area late Wednesday into Thursday.
A cutoff low will also get absorbed into the southern stream,
and that may impact our area later Thursday and Friday. Given
the tropical moisture and potent dynamics both from the remnants
of Zeta, and the southern stream low, this has the potential to
bring a soaking rain to the area. Rain may be heavy.

There is still a high degree of uncertainty regarding the exact
track of these features, but this will have to be monitored over
the next few days. Refer to the National Hurricane Center for
the latest information regarding the track of Zeta.


Rain is gradually working its way in from the south early this
morning. On and off periods of rain are expected through the
day, with a trend toward drier conditions this evening. Ceilings
will be lowering through the day, becoming MVFR late this
morning or early this afternoon, then IFR and potentially even
LIFR later this evening into the overnight hours. Areas of fog
and drizzle will also be possible overnight. Ceilings will
gradually lift through the day Monday, with VFR conditions
expected once again by mid-late afternoon. Sub-VFR ceilings
appear possible again Monday Night into Tuesday.

A boundary will remain nearby for Wednesday, and low clouds/fog
are possible, especially during the morning hours.

The remnants of Zeta may track along the boundary, possibly
bringing a soaking rain to the terminals Wednesday night and/or
Thursday along with subVFR conditions. Refer to the National
Hurricane Center for the latest information regarding the
track of Zeta.


North to northeasterly winds are expected over the waters
through the remainder of the overnight and through the day
today. Intermittent SCA level gusts appear possible through much
of the day, with possibly a slight lull during the late
afternoon hours. Winds may pick up slightly again this evening
as low pressure tracks to our southeast. Winds will slacken
later tonight, and remain sub-SCA level in nature for Monday and

A boundary will remain near the waters Wednesday, but the
gradient should be weak so winds are most likely to remain below
SCA criteria.

The remnants of Zeta may track along the boundary, impacting the
waters Wednesday night and Thursday with the possibility for
stronger winds and a soaking rain. An SCA may be needed for the
waters during this time. Refer to the National Hurricane Center
for the latest information regarding the track of Zeta.


A northerly component to the wind behind a cold front has caused
water levels to fall this morning. However, that water may pile
up near the Mouth of the Bay and return later tonight or
Monday/Monday night. Minor flooding is possible if these
anomalies do indeed return northward up the Bay and Potomac
River. As of now, it appears that the best chance for the water
to return will be on Monday/Monday night.


MARINE...Small Craft Advisory until 7 AM EDT this morning for ANZ530-
     Small Craft Advisory from 6 PM this evening to midnight EDT
     tonight for ANZ531-539.
     Small Craft Advisory until midnight EDT tonight for ANZ532-533-
     Small Craft Advisory until 6 AM EDT Monday for ANZ534-537-543.
     Small Craft Advisory until noon EDT today for ANZ531.



NWS LWX Office Area Forecast Discussion