Atmospheric River in the Pacific Northwest and Northern Rockies this Weekend

A Pacific storm and atmospheric river will impact the Pacific Northwest states and northern Rockies this weekend, bringing locally heavy low elevations rain and heavy high elevation snow in the mountains. By Sunday over the Interior Northwest, rain combined with snowmelt will increase the risk of flood hazards. Flood Watches are in effect. Read More >

Lake Effect Summary - December 18-19, 2013

Lake Effect Snowfall - December 18-19, 2013

Maximum Snowfall: Lake Erie 12" (West Falls); Lake Ontario 11.2" (Highmarket)

Duration: 24 hours +/-

Prime feature: Hybrid synoptic and lake effect.

The fourth lake effect event of the season was a combination of light synoptic snows, followed by some lake effect snows. A shortwave rode through a long wave trough over the eastern United States, and this shortwave brought several inches of snow across Western and North Central New York. Behind this shortwave, temperatures at 850 hpa dropped down to about -12C, which created enough instability over a cold, but not frozen lake surface to generate lake effect snow. Snow fell through the morning and afternoon hours off Lake Erie, before migrating northward through the evening hours and dissipated under weakening lake effect snow parameters and warm air advection. The lake effect band of snow off Lake Ontario intensified through the late morning and afternoon hours while impacting the Tug Hill region. This band too also shifted northward overnight and weakened.

Snowfall rates off Lake Erie peaked at an inch per hour, while off Lake Ontario snowfall rates peaked at 2 inches per hour. Within the higher snowfall rates off Lake Ontario thunder snow occurred late Wednesday afternoon. Given the weak lake instability, this event produced manageable snows with upwards of a foot of snow falling east of both Eastern Great Lakes.

While snows were light, gusty winds and the timing of early morning off Lake Erie did bring accidents on area roads slowing the morning commute.