Wednesday, March 30, 2016

Beautiful Week Ahead!

I had meant to get to this earlier, but then a funnel cloud occurred over Mill Creek and I had to write about that. Believe it or not, there are people who prefer stormy days with funnel clouds to beautiful, clear, warm sunny days, and I belong to that unique group. However, I'm a big fan of sun as well. In the words of John Ruskin, "there is no such thing as bad weather, only different kinds of good weather," so let's talk about the good weather ahead.

Well, on second thought, let's just talk about the good weather now. It is calm as can be on Lake Washington as I look outside my window, and the only clouds I see are some harmless cirrus clouds. Mt. St. Helens is always spectacular, but right now it is downright gorgeous. I'd love to hit the slopes of the Cascade volcanoes sometime.

Credit: US Forest Service

Right now, we have a HUGE ridge of high pressure over us. Those of you who read my blog regularly know how much I love the satellite images from the MODIS instruments aboard the AQUA and TERRA polar-orbiting satellites, so I'll post one here showing how clear it is over the West Coast. Even if you have no idea what the last sentence just meant, I'm sure you'll understand the picture.

High pressure over our area as seen from NASA's TERRA Satellite. Credit: NASA

Yeah, it's clear. By the way, that diagonal line you see simply shows the boundary of one passage around the pole of this satellite. The satellites that we usually use for meteorology are called "geostationary" satellites and are very useful because they orbit the Earth at the same velocity that the Earth is rotating, so they always stay above a single point on the equator. This allows them to get continuous shots of nearly every place on the globe. However, in order to be geostationary, they must be about 22,326 miles above sea level. Polar orbiting satellites do not have the advantage of remaining stationary over a single point, but they are only several hundred miles above the planet and can thus get much higher-resolution images.

The weather models show this too - the current UW flagship WRF-GFS model shows a massive ridge of high pressure over the Eastern Pacific.

Valid 05:00 pm PDT, Wed 30 Mar 2016 - 12hr Fcst
Credit: University of Washington Atmospheric Sciences
Also, notice how there are areas of low pressure on either side of the high - this pattern is known as an "omega block" because the flow resembles the Greek Letter omega - and it is a very hard pattern to break.

Idealized Omega Block
Credit: University Corporation for Atmospheric Research

This omega block will live up to its reputation, and won't go anywhere for the remainder of the week. 24 hours from now, the omega block has hardly moved at all.

Valid 05:00 pm PDT, Thu 31 Mar 2016 - 36hr Fcst
Credit: University of Washington Atmospheric Sciences

I don't think we'll be breaking any records, but highs on Thursday and Friday have a good chance of breaking the 70-degree mark for many areas in Western Washington, especially Friday. We "cool down" to the low 60s for the weekend, still well above our average high of 56, and turn rainy by next week. Still, we do not look stormy by any means. Spring arrived a little late this year, but I think it's safe to say that it is finally here.

Get outside, and don't forget to wear sunscreen!


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