This afternoon several shortwaves are rippling across the Pacific,
forming eventually a stronger and deeper shortwave trough along the
west coast Sunday. These features will eventually form a trough of
low pressure over the Plains early next week. Cooler air within this
trough will create a baroclinic boundary across the Ohio Valley
separating a much warmer airmass that will reside within a Southeast
ridge of high pressure. This baroclinic boundary will eventually
waver through our region Tuesday and Wednesday, with a surface low
passing either over or just to our south Tuesday night and
Wednesday. Given the placement of several features over the Pacific
(and not sampled well by upper air soundings) that will need to come
together over the western U.S., there understandably is quite a bit
a uncertainty to the Tuesday - Wednesday time period.
The cooler biased GFS would support shovelable snow across our
northern 1/3 to 2/3rds of the CWA, while the ECMWF is not as far
south with the surface boundary (and cooler air aloft). The majority
of the GEFS ensemble members also support this stalled frontal
boundary over our region though they remain with great uncertainty
as to the placement. For now will continue with chance to low likely
PoPs (as the surface low passes near us) during the Tuesday -
Wednesday timeframe, with a mix of snow and rain.