Monday, July 21, 2014

Bit Of An Upturn By Midweek?

Thunderstorm coverage increased in northern Mexico yesterday afternoon and evening. Satellite IR image (top) indicates a large MCS in Mexico south of Cochise County at 0415 UTC on 21 July. There may have been a couple of CG flashes in Cochise County also (just above graphic shows CG flash locations for 24-h through 09 UTC). The storms did produce an outflow that moved northward into the Arizona borderlands - Time series of T and Td below for Douglas shows an outflow passing there about 6 pm MST. Outflow kicked Td up by about 10F. We still need a couple more events like this to get more re-cycled moisture back into Arizona.

Interestingly, the early WRF-NAM forecasts from Atmo indicate a considerable uptick in thunderstorm activity across southeast Arizona Wednesday afternoon and evening (July 23rd). Forecast below is of low-level winds and PW valid 9 am MST on Wednesday morning. The model forecasts low-level moisture and PW to increase behind a back-door front from the east. This scenario can occur, but is a tricky one to call correctly because of the downslope winds complicating the situation. So, for now, just something to keep an eye on.

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