Saturday, March 12, 2016

Sunday Windstorm

Weather prediction models are pretty much all onboard in predicting the approach of a small, but potent, low pressure center on Sunday afternoon and evening.   Let me show you the latest  WRF model forecasts.  These maps present the predicted pressures (solid lines), winds (little barbs), and temperature.

By 8 AM Sunday the low is off the central/northern Oregon Coast.  It is not a large storm.

 It makes landfall near 5 PM, with a central pressure of roughly 980 hPa.  The southern WA coast would be getting very strong winds if that pressure pattern verifies.

 By 11 PM Sunday, the low is over SW British Columbia, with windy conditions over western WA.

I know, you want to know about wind speeds. Here are the predicted SUSTAINED winds at 5 PM.  50 kts on the southern WA coast and 25-35 kt over central Puget Sound.

 Two hours later, 35 kt sustained over Northwest Washington and 25-35 kt around Seattle.  Gusts would be stronger

If this system strengthens more than predicted or moves a bit more inland, things could be worst over Puget Sound.  Rapidly developing, small systems such as this one are very difficult forecasting problems...a slight displacement makes ALL the difference in max winds.

Bottom line:  The south/central coast will get hit hard, with gusts reaching 50-70 mph.  For Puget Sound, it will probably be similar to the storm of this week, but it could be worse.   Make sure you have batteries!

Announcement: Public Talk: Weather Forecasting: From Superstition to Supercomputers

I will be giving a talk on March 16th at 7:30 PM in Kane Hall on the UW campus on the history, science, and technology of weather forecasting as a fundraiser for KPLU. I will give you an insider's view of the amazing story of of weather forecasting's evolution from folk wisdom to a quantitative science using supercomputers. General admission tickets are $25.00, with higher priced reserved seating and VIP tickets (including dinner) available. If you are interested in purchasing tickets, you can sign up here


James Reynolds said...

it would be interesting to hear Dr Mass's opinion on why we are in this "rut" pattern where storms spin up every other day with no relief in sight. Can only assume the strong jet is simply pointed directly at us. The usual blocking high over the Nevada deserts must be long gone.

Joseph Ratliff said...

I agree with James. Seems the storm train chugged from end of November to December, then started again end of February into March.


The NWS Seattle office doesn't seem to be issuing Warnings like they used to. There used to be more specific reporting in the Warnings, which made them useful.

Recently (the last 6 months or so), the Warnings and Advisories seem more "blanket coverage" in nature ... some of them are issued but have nothing to do with my area. Thus, nothing happens weather-wise in my area. They used to be specific-enough where I knew if they were for my area.

ryamkajr said...

I am just glad all of the weather forecasters were wrong about this being a drier/warmer winter (at least as far as the drier part goes).

As much as I am tired of the constant incessant rain this season, I am glad we are getting it. I am glad our reservoirs are full. And I am glad we have something of a near normal snow pack.

That will serve us (Seattle metro) and the wider-state ag business well this year.

lhsouthern said...

What does the European model say?

windlover said...

Seems like the nws is almost afraid to say it's going to be a big deal for sure. They usually really hype things up but this time they came out with the watch, then changed it to a warning, but in their written forcast they keep saying it could change it's track and not be such a big deal, even though they say the models are all coming into agreement the closer it gets.....I guess they don't want all the criticism if it does change track? Just hope everyone prepares....better safe than sorry!

RLL said...

Seattle NWS headlines lead off with DST changes and other somewhat unimportant things. But if you click on the 'brown' wind warnings area of the map of Western Wash. lowlands the ominous warning do include gusts up to 70mph, they may be centered over Kitsap County. Seems like 70 mph gusts in central Puget Sound would lead in the headlines.

lhsouthern said...

i'll believe it when it happens

Joseph Ratliff said...

Readers should see Cliff's update: ... quite interesting.

Kelly Vander Linda said...

Can now see the low taking shape on the infrared as of 7:28AM.

Bruce Kay said...

Just to clarify my drift, I recognize that you yourself are very clearly communicating uncertainty in your post. I'm not suggesting you don't, quite the contrary - experts are well versed in just that.

The problem is that we ( the inexpert) filter everything we take in by our own common sense, with which we create our own narrative, to make sense to us. As an example, the polarization of belief in climate change is primarily an effect of moral psychology, something we are well armed to do, rather than validate the science, something we most certainly are not.
Moral psychology, as you are no doubt aware, is a sucker for certainty! Humans in general are suckers for a narrative of certainty. That is the basis for fraud after all.

Maybe a good way to illustrate "confidence" is to show us where you are on the Dunning kruger graph of percieved / observed expertise, and the path that leads there. Considering that most of us are on the far left quadrant, it begins to frame our perceptions of uncertainty quite well

Lori said...

I'm glad we're back to normal!