Friday, March 20, 2015

First Day Of Spring Dawns Bright And Sunny

Today is the first day of astronomical spring, as the sun begins its northward trek to summer. Officially spring begins at 3:45 pm MST this afternoon. Our meteorological spring started back on March 1st. Regardless, today has dawned clear and sunny - above at 7:30 am and here at the house we are enjoying a riot of penstemons blooming almost everywhere (below).

Yesterday's coverage of rainfall across the ALERT network was down considerably from Wednesday's 100% areal coverage. At 7:00 am MST this morning 40 sites had measured rain during past 24-hours (bit over 40% coverage), with the northeastern portions of the network and metro Tucson being almost skunked (above is metro west sector and below is southwest sector). Thunderstorms to the west and south produced a few spots of heavier rain (most amounts were well under 0.20"), with 7 sites having 0.25" or more (max of 0.83 at Tubac, on the far south edge of the network). Almost a summer-like afternoon, with fairly widespread thunderstorms affecting Arizona, New Mexico, and Mexico - second graphic below shows detected CGs through 8:00 pm MST (from Vaisala).

Today, our Easter-egg shaped, 500 mb closed low continues over central Baja (above 12 UTC analysis from NCAR RAL) with quite cool temperatures over the Southwest. The persistent ridge continues from the Northwest U.S. across western Canada, with the flow splitting about over Mt. Shasta, California. The TWC sounding plot (below from SPC) indicates a touch of CAPE at low elevations, given some sunshine today. Steering winds have almost vanished, so afternoon storms over mountains won't go far, although some may drift over lower elevations. 

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