Update: Winter wants another shot at snow | Weather

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Update: Winter wants another shot at snow
Update: Winter wants another shot at snow

(This week's weather forecast has been updated as of Sunday at 4:10p.m.)

March is often a month where Mother Nature plays 'weather whiplash' with the Northwest. It will be sunny and spring-like one day, and we'll jump right back into full-blown winter the next.  That will definitely be the case this week, so get ready for a temperature roller coaster over the days ahead.

A good-sized cold front is wasting no time in moving in to Western Washington...it's sped up quite a bit since yesterday, and cold air will quickly plunge in behind it.  As such, Sunday's sunshine never quite materialized...the clouds are already crowding in to the region, and highs only topped out in the low 50s as a result.  Rain will kick in at the coast after dark, and will work it's way toward the I-5 corridor during the overnight hours.  Lows will mainly drop into the mid to upper 30s by sunrise.

It's after sunrise where things get really interesting for most of us.  The air will cool quite dramatically behind the frontal passage, and the rain will turn to snow for many of us on Monday morning.  At this point it looks like we'll see some wet snow from  the Strait and into Skagit and Snohomish counties between 6 and 8 a.m.  The snow moves south into King and Pierce counties between 7 and 10 a.m., and then sweeps through Thursday from 9 to noon.  Amounts will vary greatly, with most of us on the lower end of the snow totals, but at this point I think we'll see 0-1" around sea level, and 1-2" of wet snow from 500' on up by noon on Monday.  Some spots in the foothills may see 2-3" of wet snow by mid-day.  For early March, this is significant!

Monday afternoon will be very chilly and GUSTY, which will give the air even more of a wintry bite.  Northwest gusts to 25 through Admiralty Inlet will clash with southwesterly gusts of 25-35 over the Sound, resulting in an afternoon Puget Sound Convergence Zone.  This will bring in another round of snow in King and Snohomish Counties, with another inch possible along the Snoho/King county line.  Highs on Monday will be in the upper 30s and low 40s, which is about 10-15 degrees below average for early March.

Monday night will be VERY cold, with lows mainly in the 20s around the Sound.  This will allow any snow that did fall to stay put, and the roads could be very icy on Tuesday morning.  We'll see a few leftover snow showers early Tuesday, but they'll be very isolated and will wind down quickly.  The thaw out will begin Tuesday afternoon, with drying conditions and partial afternoon clearing.  Highs will still struggle to hit the lower 40s, but you'll begin to feel the warm-up coming late in the day.

The pendulum swings in the other direction by mid-week.  A big ridge of high pressure builds in over the Western U.S., and Wednesday will be lovely here in the Sound.  Partly to mostly sunny skies will allow temps to head back toward at least 50 degrees.  Thursday and Friday will be even warmer, with 50s to near 60 in the warmer locales.

Clouds thicken again Friday afternoon, a sign of rain to come again by Friday night.   The weekend will kick off soggy, with lowland rain and mountain snow on Saturday.  Sunday looks drier and brighter at this point.

In the meantime, get ready for some difficult driving for the Monday commutes...!

Meteorologist Shannon O'Donnell
The KOMO4 Forecast Team

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