Monday, May 6, 2013

The Big Split

"When you come to a fork in the road, take it"
- Yogi Berra

Strong split flow presently persists over North America, with a strong polar jet over Canada and a strong subtropical jet over Mexico and the Gulf of Mexico.  I've crudely identified these jets on the dynamic tropopause (jet level) wind speed analysis below.  This strikes me as an unusually strong example of split flow in May, but some digging is needed to ascertain how unusual.

This split flow extends further downstream across the North Atlantic and into Europe and Africa, making this a hemispheric-scale event.  This is a good time to be flying westward across the North Atlantic or continental US as you aren't fighting the westerly flow that is commonly found at mid latitudes.

One nice aspect of this pattern is that it doesn't favor strong Intermountain cyclogenesis and associated southwesterly flow.  This has contributed to the dearth of dust storms this spring.

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