The models have been all over this for days now. What will be the strongest high aloft ever recorded over northern Alaska outside of summer is building this weekend. At Barrow the highest 500mb height ever measured in January is 566dm (data since 1946). The 12Z GFS is forecasting max 500mb heights for this event at Barrow of 580dm, 583dm at Kotzebue and 584dm at Ambler. At Fairbanks GFS has max height of 577dm, which would be a January record.
This will also be another nice example of how very high surface pressures will not be associated with particularly low surface temperatures. Image from the 1200 UTC Jan 08 ECMWF valid 3am AST Tuesday, from Plymouth State.
Just trying to follow this, Rick - what is "dm" - couldn't find an understandable explanation on the web as yet? Thanks.
ReplyDeleteTerry
Terry,
ReplyDeletedm = dekameter = 10 meters.
Technically, this should be geopotential meters (hence the gpm on the Y-axis of the sounding plots I put up), but for practical purposes just think meters. So a 580dm 500mb height means that the altitude above MSL where the pressure is 500 millibars is 580dm = 5800 meters.
Rick
Thanks for your quick response. As you can tell, I'm only an interested reader, no weather science in my back ground (and certainly had not come across dekameters), but Alaska's winter weather, in the Interior especially, has always been interesting to me - I used to live there :-) Is the effect still to hold the temps at the surface steady? Terry
ReplyDeleteTerry,
ReplyDeleteI try to keep the technical jargon down, but this event is so extreme that it seemed to warrant a post. Also, I use this blog as kind of an on-line archive/reference for myself.
Anyway, thanks for your interest. Are you presently enjoying summer "down under"?
Rick
Rick, no problem with the "jargon" - one just has to learn a bit more :-) As to summer, we have had record rain (almost a year's amount in a day), subsequently, record flooding (higher than ever recorded), a plague of locust, mosquitoes etc, another flood, and it's only mid summer! And I'm not in Queensland which is still suffering record breaking flooding, almost statewide. The "lucky country" is taking a hit this year! Cheers!
ReplyDeleteYeah, between the fires in 2009 and floods this summer, Australia might want to acquire a new moniker!
ReplyDelete