Winter Storm Watch 6, NWS Baltimore/Washington

Anne Arundel County, MD, Calvert County, MD, Charles County, MD, Prince George's County, MD, Saint Mary's County, MD, Albemarle County, VA, Amherst County, VA, Arlington County, VA, Augusta County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Greene County, VA, King George County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Rockbridge County, VA, Spotsylvania County, VA, Stafford County, VA

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
338 PM EST Thu Feb 11 2021

.SYNOPSIS...
Multiple rounds of wintry precipitation will be possible
through this weekend. A brief lull in winter precipitation is
expected early next week as high pressure builds over the
region. Another system will impact our region by Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Precipitation is starting to spread back into southern portions
of the forecast area, and will continue through the night
tonight as a weak disturbance passes to the south. This period
of overrunning precipitation will occur as high pressure builds
to our north, which will encourage drainage of cooler air into
our area from the north as time progresses on. As a result, this
precipitation is expected to fall nearly all in the form of
snow. A brief mix with rain may be possible from central
Virginia to southern Maryland at onset. 12z guidance has trended
upward with QPF values across the southern tier of the forecast
area. As a result, snowfall totals have been adjusted upward
slightly. We're now forecasting 2-3 inches across much of
central Virginia, and 1-2 inches from the Fredericksburg area to
southern Maryland.

The northern edge of the snow is forecast to get close to DC
tonight, but currently we're expecting it to stay just to the
south. It's not out of the question that a quick coating to half
inch of snow could be possible in DC if the area of snow were to
trend slightly further north, but at the moment that is just a
possibility, not the expectation. Locations to the north of DC
are expected to remain dry. Lows tonight will be in the 20s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
The bulk of the precipitation should come to an end prior to
daybreak tomorrow, but a few lingering flurries may be possible
during the morning hours. Cloudy and cold, but dry conditions
are expected thereafter. Temperatures will only make it into the
upper 20s to around 30, with cold air continuing to drain into
the area on a north to northeasterly wind. Wind chills tomorrow
will hold in the teens and 20s.

By Saturday, attention will turn to yet another disturbance,
this time approaching the area in southwesterly flow. Cold air
will remain entrenched at the surface, but a prominent warm nose
is expected to move in aloft as warm advection ensues in
advance of the disturbance. With temperatures at the surface
holding in the 20s to around 30, and temperatures aloft climbing
well above freezing, freezing rain appears like it may be the
predominant precipitation type with this system. Some brief
mixing with snow and sleet may be possible as well, especially
further north and west. Guidance has trended slightly downward
with QPF totals. However, with surface temps in the 20s, an
impactful event appears likely, since most, if not all of the
rain that falls should accrete into ice. At least a glaze
appears likely in most spots, with a tenth to two tenths of an
inch possible. If wetter solutions like the Euro or Canadian
were to verify, even more significant ice accumulations would be
possible. We'll continue to monitor trends and adjust the
forecast as necessary as we move closer to the event.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
An active pattern still looks to persist through the long term
period. Arctic high pressure is expected to hold firm from
southeastern Canada southwestward into the Great Plains. A very
strong reinforcing high pressure will build eastward across the
Great Lakes and into the Northeast. Its starting pressure is progged
to be near 1050 mb when it exits the Plains. This strong high
pressure will act to lock cold air in near the surface, but the
depth of the cold air is in question heading into early next week.
That will play a role in precipitation type associated with yet
another area of low pressure, which currently looks to approach the
region Tuesday.

Yet another area of low pressure may approach later next week, with
not much change in the overall pattern resulting in the potential
for similar wintry threats, though with less confidence given the
extended time range.

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
Another round of precipitation is expected later this afternoon
into tonight at CHO. This may start as a rain/snow mix this
afternoon, before transitioning over to all snow. A couple
inches appear possible before it winds down later tonight. It's
possible that it may end as a period of freezing drizzle.

Further north, dry conditions are expected at the terminals,
although snow may get close to DCA. It's possible that a little
light snow may occur there overnight, but we're currently
leaning against that solution. Worst case, a coating to a half
inch could be possible. Other than that, ceilings are slowly
expected to improve from IFR to MVFR at the terminals to the
north of CHO later tonight into tomorrow. Quiet weather
conditions are expected tomorrow. Sub-VFR conditions appear
likely Saturday into Saturday Night, with freezing rain
occurring at most if not all of the terminals.

VFR conditions may return for a time Sunday into Monday.

&&

.MARINE...
A prolonged period of north to northeasterly winds will persist
over the waters through the next several days. Low-end SCA
magnitude winds are expected on the bay through the night
tonight, with borderline SCA winds lasting through Saturday.
Confidence was not yet high enough to add on to the the current
SCA that runs through 6 AM tomorrow morning.

Northerly flow is forecast to persist Sunday into Monday, but speeds
should stay generally below Small Craft Advisory criteria.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Winter Weather Advisory until 7 AM EST Friday for MDZ017.
VA...Winter Weather Advisory until 7 AM EST Friday for VAZ025-026-
     036>039-050-055>057-503-504-507-508.
WV...Winter Weather Advisory until 7 AM EST Friday for WVZ505-506.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ540-
     542.
     Small Craft Advisory from midnight tonight to 6 AM EST Friday
     for ANZ531-539-540.
     Small Craft Advisory until 6 AM EST Friday for ANZ532>534-537-
     541-543.

&&

SYNOPSIS...KJP
NEAR TERM...KJP
SHORT TERM...KJP
LONG TERM...DHOF
AVIATION...DHOF/KJP
MARINE...KJP

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
136 PM EST THU FEB 11 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0135 PM     SNOW             ELLICOTT CITY           39.27N  76.80W
02/11/2021  M4.2 INCH        HOWARD             MD   TRAINED SPOTTER

&&

EVENT NUMBER LWX2102212

CPB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
335 PM EST THU FEB 11 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0900 AM     SNOW             1 NW RIDGELEY           39.65N  78.78W
02/11/2021  M5.7 INCH        ALLEGANY           MD   TRAINED SPOTTER

&&

EVENT NUMBER LWX2102213

CPB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
416 PM EST THU FEB 11 2021

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0237 PM     SNOW             3 SE MCCOOLE            39.42N  78.94W
02/11/2021  M6.0 INCH        MINERAL            WV   TRAINED SPOTTER

&&

EVENT NUMBER LWX2102214

CPB