Regional Radar at 1400Z This MorningMorning showers and a few thunderstorms are drifting southeastward across central and southeastern Arizona. This will certainly complicate the forecast today.
The up-tic I mentioned yesterday was mostly to west and north of the Tucson metro area. I see that Prescott and Phoenix both had thunderstorms with gusts to 55 mph and there was one severe report in south Phoenix as a large gust front headed south in the evening. Earlier, around 5 pm, a cell produced a downburst near Ryan Field, west of Tucson, that took down 20 power poles. But as for rain in the Pima County ALERT network, only 13 sites reported measurable rainfall. So, locally it was a down-tic in area coverage of storms. The Phoenix gust front came all the way south through the Tucson area, but the storms died out to the north and west of us.
The 500 mb anticyclone continues to have two circulation centers (one along central Californina coast and one in northern Mexico somewhere southeast of Tucson) with a weak and meandering trough between the centers. The shower activity this morning is occurring in this trough zone. The NAM indicates little change through tomorrow and then shifts the California center inland and northward so that at 84 hours there is a single 500 mb anticyclone over Utah. Winds aloft remain weak and the trough over Arizona does not link with a stronger S/W coming south – so the situation over Arizona remains pretty stagnant next couple of days. There’s enough moisture for daily storms but not enough for really serious amounts of CAPE except in mountains.
From today’s NWS Tucson early morning Forecast Discussion: “LIKELY THERE WILL BE CONVECTION SOMEWHERE IN THE CWA EACH DAY...BUT COVERAGE AND INTENSITY WILL BE DETERMINED BY MESOSCALE FEATURES ROTATING AROUND THE UPPER HIGH...UNRESOLVABLE MORE THAN ABOUT A DAY IN ADVANCE.”
What more can I add, except that I’m certainly grateful that I don’t have to do a deterministic forecast for each the next seven days!
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