2006-2-12-Forecast
Trend toward troughing in the West and eventually off the West Coast still looking good. However, evolution is complex and appears to be favoring a delay in significant pcpn till late this week at the earliest...I see nothing significant before Friday at this point, and this is problematic.
The basic long-wave evolution scenario that Ed Szoke noted on 10 Feb is still anticipated. The bitter cold Arctic air in the Far North is approaching Hudson's Bay at the moment, but the main initial thrust of this will be into SE Canada and the Maritimes. A second thrust at midweek is anticipated to carry
the cold air westward into BC and offshore and into the Pacific Northwest, albeit with considerable modification. This is partly in response to cyclogenesis in the Western Pacific and ridge building into Alaska with the warm advection ahead of the deep cyclone as it moves into the Bering. Strong pressure rises are occurring in the western Gulf of Alaska at present. It appears that the trough
presently north of Hawaii into Alaska will split, with the southern portion cutting off N of Hawaii and the northern portion moving ashore BC tomorrow and Tuesday, then becoming part of the troughing over BC and the Northwest midweek. With widespread cold advection at low levels offshore and a trajectory from the far North, any onshore flow that does develop as result of near-shore cyclogenesis in association with these events and the overall retrogression of the western trough is going to be quite dry, making any significant pcpn in HMT (or anywhere along the West Coast) unlikely before Friday at the earliest.
However, with the the progs indicating continued retrogression over North America and Eastern Pacific, and the possibility of a major trough setting up off the WestCoast by next weekend, I believe chances are good for an event in the HMT sometime in the Sat 18th to M 20th time frame. Such a trough may well entrain the anticipated cutoff low N of Hawaii noted above (and associated moisture) into its circulation, creating a decent moisture plume into the coast and a nice pcpn event. I'll be attentive to this possibility next 2 days.
John B.