Enter your email address:

Delivered by FeedBurner

Tuesday, October 13, 2009

Why, hello there October!

In what might be considered an appetizer for the usual fall stormy season, an abrupt change in the weather pattern is under way, going from dry and chilly to wet and windy as three storms make their way toward our zip codes this week.

Let's talk about the first one first, as it'll be the strongest -- it's remnants of a typhoon that went through Japan last week. But it appears most of Western Washington will be spared the worst of the storm, with the greatest calling card being gusty winds in the Cascade foothills and along the coast and western Strait of Juan de Fuca on Tuesday.

The storm begins its approach Monday, keeping us cloudy, but rain looks like it'll hold off until late Monday night.

On Tuesday, the storm is well-developed with a central pressure of about 970 milibars -- in the moderately strong category -- but it is forecast to turn to the north well offshore and drift back toward the southern Gulf of Alaska. Since the center of the storm is not expected to make landfall, this will spare most of our area from any strong, damaging winds. (A typical windstorm would have the storm moving inland around Vancouver Island or the north Washington coast as we need that center to be to our north to pull in the strong, southerly winds.)

However, this does present a windy situation for the Cascade foothills starting Tuesday morning. We have some lingering arctic air in Eastern Washington, which has higher pressure due it being cold and dense. Meanwhile, as that storm center goes by off our coast on its way north, it'll create a big difference in pressure between Eastern Washington (high pressure due to arctic air) and off our coast (strong low pressure due to storm).

This is a classic setup for gusty east winds to come shooting through the mountain passes and through the foothill communities like North Bend, Enumclaw, Gold Bar, Cumberland and Snoqualmie -- those of you who have lived there for a winter know all about this. A WIND ADVISORY is in effect for these areas from 3 a.m. to 6 p.m. Tuesday.

The good news is, the storm appears to be far enough offshore and a good chunk of the arctic air in Eastern Washington has moved far enough east that we're not talking major winds. Call it noticeably windy -- perhaps gusts to 45-50 mph that might cause a few power outages/tree falls -- but not the 60-80 mph gusts you can sometimes get in a major wind event over there.

In addition, the western Strait of Juan de Fuca area (Neah Bay, Clallam Bay) can get strong east winds during these events as well.

Of course, it's not just the wind but the rain, but in another bit of good news (for us), it appears most of the rain intensity will be focused in Northern and Central California, leaving us with some light to moderate rain at times, but barely noticeable on the fall storm scale of things. (Could this be a preview of this winter? El Nino typically focuses what would normally be our heavy rains to California. Usually El Nino doesn't get going until after New Year's, but maybe it's a warning shot for California.)

But you can track the rain with our new interactive radar. Maybe bookmark it and keep it handy this week.

And not to forget -- it could also bring an early season snow to Snoqualmie and Stevens Pass on Tuesday -- but just 1-3" at most and with snow levels around 3,000 feet, and I'm thinking it'll be a fringe event at the Pass, and then snow levels quickly rise back to 6,500 feet Tuesday night so whatever falls will quickly melt.

So to recap Tuesday: Rainy and breezy, with windy conditions along the Cascade foothills to 45-50 mph and along the coast and western Strait, but nothing too extreme on either the rain or wind scale. In fact, winds might be near calm across places that are not susceptible to an east wind. And maybe some flakes up at Snoqulamie and a few inches at Stevens Pass.

The east winds taper off Tuesday night as the storm moves off to the north. Meanwhile, a front associated with the storm moves in early Wednesday morning, bringing another round of steady rain for a while. It won't be until after this front passes around mid-to-late morning that the Puget Sound area and other spots get their usual southwest breezes with this storm, but by now, the storm center is way far away, and while it'll be a breezy to windy day on Wednesday for most everyone else, including the Seattle metro area, I don't expect wind speeds to get over 30-35 mph, except for maybe the coast (40-45 mph) and Northwest Interior (35-45 mph) -- all old hat for October.

Now, the pattern shifts again toward the end of the week as with that main storm center pulling off to the Gulf of Alaska, it'll pull the storm track back to the north along with it. Two more systems (not as strong) are expected to rotate around the main storm Thursday and Friday, giving us a better shot at heavier rain. The Thursday one is more the rainmaker and breezy-but-not-too-windy, while Friday's at this point is more wind than rain (usual fall storm windy -- 25-35, gusting to 40-45, maybe 50 coast and north. No east wind concerns), but cumulatively, the rain amounts will bear watching. It doesn't look too extreme right now, but we'll keep tabs on it this week.

Once we get into the weekend, the pattern calms down to just some lingering scattered showers. But November's main course is just around the corner.


Post a Comment

Blog Roll