An approaching front on Friday will spell the start of a 24 to 36-hour period of storminess across Western Washington with some gusty winds, mountain snow and the possibility of thunderstorms.

The front will slam into the Washington coast with gusty rain squalls on Friday afternoon, with rain overspreading parts of the Puget Sound in time for the afternoon commute.  With typical rain shadowing by the Olympic Mountains, areas south of Seattle look to pick up more rain to end the work week than areas from Seattle north to the Islands.  However, most areas will get wet.

Winds will also be gusty along the coast and from the north Sound through the Islands late Friday.

Snow levels fall rapidly as the front hits the Cascades, with snow falling at 2,500 feet overnight Friday into Saturday morning.  That snow level will continue to drop to 1,500 feet by Saturday night.

The passes will begin to see problems with accumulating snow beginning Friday night.   

On Saturday, a potent upper-level low pressure system will move across the Northwest.  This low will have some very cold air aloft associated with it. 

A "cold pool" of air aloft creates unstable atmospheric conditions, where warmer surface air can rise more rapidly condensing into scattered showers and some heavier downpours.   With the low freezing levels, some small hail or graupel is possible in the stronger cells.   In addition, claps of thunder could be heard at any time on Saturday with the stronger cells.

Windy conditions pick up again on Saturday.  Wind speeds will be in the gale force range for many of our local waters, the Strait and the coast during this time.   Wind gusts along the north coast and the islands and north interior waters could gust to 50mph on Saturday, with wind gusts from 20-30mph across the rest of the lowlands.

Saturday's snow could be heavy in most of our mountain ranges, with the snow level remaining around 1,500 feet.  Stronger downpours could briefly drag snow levels a bit lower, and some higher foothill locations could pick up quick hitting snow showers mixed with rain Saturday.

Rain and mountain snow showers begin to subside by Sunday and winds calm as well.

(Join me tonight at 7:30 p.m. for the Thursday night KIROTV.com Weather Chat!  http://www.kirotv.com/weatherchat )