Friday, May 03, 2013

Look To The West For Next Week



As the dusty winds weaken, we can look to the west as interesting events are happening over the Pacific at lower latitudes. I have shown 500 mb forecasts from the ECMWF operational model above and below for the coming week. Each forecast is from this morning and each is valid at 5 am MST, i.e., on Monday, Wednesday, and Friday mornings next week. There is a weak, 500 mb short wave crossing the Southwest on each day, as the 500 mb ridge changes its shape and strengthens along the West Coast. So, the question will be whether southern Arizona will get precipitation from any of these short waves? There will definitely be periods of Pacific cloudiness and virga and mammatus. Rain in the gauge here, though, is unusual during May, so we'll have to watch as the week transpires.

An interesting complexity is that a broad plume of moisture is developing northward at around 130 degrees west, as indicated in this afternoon's 21 UTC blended precipitatble water product from CIMSS at Univ. of Wisconsin (bottom graphic). This tropical/subtropical plume can be contrasted with the sharp, narrow, and distinct atmospheric river that extends from Hawaii north to the Gulf of Alaska.



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