Thursday, January 18, 2007

Fresh Air


T/weren/t all that long ago when one mT anticyclone after another...filled to the brim with warm PAC air...was flooding the Lower 48. Monthly T departures of 6°F were not uncommon. The UA flow was just plain flat and that was that.

Well into MET winter...winter was a no-show. We/d all been stood up...again.

The PV...anchored over ern Asia...was directing wave after wave of LOW pressure into wrn CN and srn AK. Whistler Mt. in British Columbia and Alyeska...AK benefited from the atmosphere/s early winter largess by piling up history-making snowfalls.



For whatever reason... weakening el Nino...Comet McNaught...Democrats taking control of Congress...the PV began a huge pivot and lunged more than 90° E to positon INVOF Hudson Bay. What followed was the beginning of winter wx across much of the CONUS.



In recent days...the ECMWF has been advertising another migration of a cold anomaly headed for the Hudson Bay...once again originating from the ern shores of Asia. The following progs pick up this feature near the IDL. Once it reaches it/s final destination...it would ensure a continued supply of fresh...well-chilled arctic air masses over the EC.

D+0 @ 100 mb. Warm stratosphere ==> cold troposphere.

D+7 @ 100 mb

Note the new Hudson Bay vortex in the 5H Z prog below...and the well-inland wrn CONUS ridge axis.



So with all this cold air lolly-gagging around...where/s all the snow?

FOTMI...the current and forecast planetary flow regime...where the NAO is expected to hover below zero...is not conducive for nor'easters. Sure...there/s a ridge-W / trof-E configuration...but the W-ridge is positioned too far E. Cyclogenesis is occurring...but it/s occurring well offshore where the fishes sleep.

A little retrogression wouldn/t hurt the cause. Nor would it hurt if the the new Hudson Bay vortex sets up a tad west of the old one...but alas...the D+7 prog suggests otherwise.

Most years past there have been ~10 contest storms. It/s long past midnight this year for Contest #1, eh?

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