On Sunday, 22 March 2015 22:42:13 UTC, Weatherlawyer wrote:
On Sunday, 22 March 2015 15:25:44 UTC, Stephen Davenport wrote:
"I thought the start of the tornado season was identical to the start of the hurricane season on the Pacific coast."

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It isn't. "Official" East Pacific hurricane season starts 15th May (1st June for the Central Pacific). For tornadoes the "season" is widely recognized as being March through June - the period when tornadoes most frequently occur, although there have been outbreaks in every month of the year. There are far fewer hurricanes outside of their designated season.

Odd they are looking at the Southern Pacific cycle. Although it obviously coincides with a lot of detail in North America, the run of the weather in the southern Pacific is south-easterly.

I have always considered the effect most likely to is the Lake Effect. I am sure it is part of tat family of weather phenomena. Such events occur with a Davis Straight/Greenland High and a cyclonic system to the south of that.

The most powerful airstream, at sea level, from such a situation is inland, a contra flow as it were. I'll have to go through my charts and see.

Damn, I have just realised why tornado spells are so similar to volcanic ones. It is the contra flow. Oddly if you look at the Canadian Arctic chart you will see that the flow is in from the north through North pacific waters somewhere around the Bering Straight. It then joins the easterly flow along the Aleutians.

But on the east coast the air stream must also include an interaction between two systems on the same longitude providing a westerly, snow filled flow over the Great Lakes. In summer that must be getting to the Mid West somehow.

That is where the tornadic stuff comes from. Volcanic eruptions move entire cyclonic systems east. And in the North Pacific a blocking High develops in the Gulf of Alaska (IIRC) or is that for large earthquakes?

It still fails to uncover the cause of course but that is because the cause must cause the course of the no... hang on.... because the cause causes the course...

Ehh.. I've got an idea. Hang on.