Sunday, July 23, 2006

Emilia and surge of moisture into Arizona

Emilia is aproaching 20 N and 110 W this evening. She is moving into the region where I've observed that Tropical Storms and Hurricanes usually trigger a significant surge of very moist air northward up the Gulf of California.

I've posted three images - CLICK HERE - the first shows IR imagery of Emilia at 2030 UTC on the 23rd, the second shows IR imagery of Emilia at 0100 UTC on the 24th, and the third shows the current NHC forecast for Emilia. I've highlighted, in light green, what I consider to be the critical region that a tropical system must move through to trigger a northward surge of moisture up the Gulf of California. The latest IR image shows that Emilia has an eye and that it is approaching this critical region. Current observations from La Paz and Mazatlan indicate that such a surge may have already begun at the south end of the Gulf. Operational forecast models are usually very slow in their forecasts of such an event.

I expect that a surge of high dewpoint air will likely arrive at Yuma, Arizona, as soon as 1400 UTC tomorrow morning (and if not by then, within the ensuing 12 hours). The surge event triggered by Emilia will be hard to differentiate clearly from the outflows likely from two significant MCSs that are also moving over the Gulf of California this evening - see the most recent IR satellite image.

Regardless, it appears that the next couple of days will be far more interesting than the past several!

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