Tuesday, June 18, 2013

We Are in Outlier Mode

There's some wild weather to be found in western North America thanks to a jet stream that is in outlier mode.

The dynamic tropopause (jet level) analysis for 6 PM MDT yesterday afternoon shows a high amplitude upper-level ridge over Alaska, a short-wave trough over the Yukon, and a closed upper-level low off of the Pacific Northwest coast.

The impact of the Alaska–Yukon ridge-trough system on the weather of parts of Alaska is astounding.  How about a maximum temperature of 90ºF in Valdez yesterday.  How crazy is that?  Their previous record high for the day was 75ºF.  It also broke their all-time record high of 87ºF.  Have a read of the rather enthusiastic record event summary from the National Weather Service.  

Meanwhile, ahead of the closed low off the Pacific Northwest coast, Utah is mired in fire-weather hell. How about these observations from Milford yesterday where at 3:52 PM MDT they reported a temperature of 90ºF and a dewpoint of -18ºF for a dewpoint depression of 108ºF and a relative humidity of 1%. 

It will be even hotter today, although we are due for a cool down beginning tomorrow.  The cause of that cool down is the migration of the closed low off the Pacific Northwest coast into the northwest interior.  Yeah, it was hot in Alaska, but how about some freshies for Glacier National Park?  Looks like a good possibility for tomorrow night and Thursday.

Yup, Mother Nature giveth, and Mother Nature taketh away.  Weird weather happens when the atmosphere is in outlier mode.  

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