Wednesday, December 27, 2006

Time for a Change

There/s plenty not to like in the LR progs...not the least of which is the rabid PAC jet flooding the lower 48 with unseasonably mild temperatures and a dearth of EC snowfall. Run after run its little mo' than mo' of the same.

Hints of change to the current pattern are hard to come by. Progs alone aren/t enough. Time to strap on the synopticoscope.

In recent days...several events have occurred that suggest changes to the status quo. Whether it/s a change for the better remains to be seen.

The most significant event is the relatively large anticyclone (1040+ mb) coming off the Asian continent. This has shifted a persistent PAC storm track along 40 / 50 into NW PAC to one where coastal storms rise rapidly in latitude into the Bering Sea and wrn AK. Previous HIGHs coming off the continent were relatively small and weak (1024 mb) with new 'fish' storms forming every three days off the coast of Japan. The storms crossed the PAC...crashing ashore INVOF SEA and with time...BC. Whistler Mt...BC has measured 20' of record snowfall YTD with four months left to go.



Over the past few days...the PAC storm track has farther shifted N into ANC and toward the Aleutian Is.

The second notable change is the erosion of the mid-lvl omega block with its closed center over England...France...and Germany. The area is in transition to a fast...zonal flow as the closed anticyclone sets up to the S over the NW coast of Africa.





Third...the Icelandic LOW...one of AO/s three poles... is W of Greenland today. This feature has generally been E of Greenland since November...a characteristic of +AO phase. A position W of Greenland is favorable for the negative AO phase.



Last...LR models retrograde the sub-tropical heat ridge into the Caribbean Sea and GOM by end of the forecast period.



The change in the PAC storm track is the best sign of improvement for downstream conditions b/c it strongly influences one pole of the AO teleconnection. Add in the fx of a strengthening pole in the N Atl. The third pole over the Azores is weak b/c of its proximity to the strong ridge.

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