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NWS Updates Weekend Storm Threat

January 16th, 2020 by WCBC Radio

Canadian high pressure will settle overhead Friday through
Friday night, causing dry but cold conditions across the area.
Low pressure will develop over the Plains and track toward the
western Great Lakes Friday night before intensifying as it
tracks through the Great Lakes Saturday. The high over our area
will weaken and shift well off to the northeast.

Usually, this type of track with low pressure means that the
main p-type would be rain. However, there will be plenty of cold
and dry air in place ahead of the system. Therefore, as
precipitation develops from isentropic lift (warm advection) and
frontogenetical forcing there will be an evaporative and
dynamical cooling effect that offsets the strong warm advection
for a bit.

Precipitation is expected to move into the area (especially
northern VA, eastern WV, central and northern MD) very late
Friday night into Saturday morning. Temps should be cold enough
to support mainly snow during this time. However, there is some
uncertainty as to how much precipitation there will be during
this time due to model divergence in solutions. For now, did
lean toward the solutions with a little lighter QPF (ECMWF,
EPS, GFS), and this is because there will be plenty of dry air
to overcome and the main forcing mechanism for this precip will
be frontogentical forcing at the mid-levels. This forcing will
be outrunning the main upper-level system over the Great Lakes.
Having that been said, accumulating snow is likely across many
areas Saturday morning and even if amounts are light, it will be
impactful due to the cold conditions leading up to the event.


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