Forecasting the first "Arctic Blast" of the season

... okay, maybe the title is a bit extreme. But two of my three favorite "analog years" (1955-56 and 1964-65, but not 1998-99) featured a cool-to-cold period in mid to late November. Moreover, the pattern we've been in through October occasionally leads to such a cold shot down the line.

Add to those little hints that the GFS ensembles (and the latest 12z operational, though that's not really fair since it's basically meaningless) are starting to like the idea of an Aleutian blocking ridge and a downstream trough over the Pac NW in the 11- to 15-day range, and there are at least some signs that the northern tier and Pac NW could see a cold shot this November. Now, often when the GFS ensembles begin advertising a significant pattern change, they are way too quick to do so. Usually it seems that an "actual" pattern change occurs a week or two after the models initially showed it. That's why I say the best chance would be mid-late rather than early-mid November.

Typhoon Chaba to become potential Pac NW windstorm threat

It's still very early, and there are lots of different scenarios that could potentially play out in the end... but the GFS has recently been flirting with the idea that a chunk of energy from former typhoon Chaba will cross the Pacific, arriving just south of the 40N, 140W benchmark by day 7 (on the heels of another moderately strong extratropical cyclone further north). Developing/bombing storms south of this benchmark are much more likely to make landfall on the Washington or south Vancouver Island coast, bringing the potential for a windstorm to the big cities of the Pac NW.

As of now, dynamics look favorable for a strengthening system and minor/moderate windstorm for Seattle/Portland. However, 850mb baroclinicity and jet strength, while indicative of a strengthening storm, are, at face value, not enough for a true major bomb a la Dec 1995 or Oct 1962. But it has certainly piqued my interest, and I'll be tracking this one closely until the models drop it.

自己紹介

Hi, all!

I'm Michael Goss, from Portland, OR, USA. I am a meteorologist (B.S. in Atmospheric Science at the University of Washington), and I currently work as a forecaster in the wind energy industry (so I certainly can't post anything that would compromise my employment there). I've been alive for slightly more than a quarter century.

I'm going to use this here blog as my personal weather page, focusing on forecasting, and in particular, medium- to long-range forecasting (beyond day 5). In other words, I'm going to engage in tasseography with weather models and ensembles. Actually, I intend more to focus on potentials than actualities.

Anyway, that's about it. I have two topics in mind (that inspired the creation of this here blog), and I'll address them in separate posts.