Morning Rains And Thunderstorms in Southern California

First a brief summary of yesterday - it was a fairly typical summer thunderstorm day yesterday with small, isolated to scattered storms, wandering around. One small cell tried to delop at dark nearly overhead - we had one rumble of thunder around 8:30 pm MST and a trace of rain. Some nice lightning before dark to the south-southwest. Rainfall amounts were generally quite light. At 7 pm last evening 25% of the ALERT sites had had rainfall, and this morning the coverage for past 24-hours was up to about 45%. Here in the greater Tucson area 8 of 20 sites had light showers. Across the entire network there were only two amounts greater than 1/2 an inch, and those were in the Catalinas.

Rare morning storms today in southern California (where Albert Hammond says it never rains!) - see plots from around 1400 UTC above of radar and surface observations.

The Tucson morning sounding (above) shows high PW and an apparent increase in CAPE, which will help support an uptick in storms today. PWs are very high from southern New Mexico westward into southern California. An unusual occurrence at Yuma this morning, as dewpoints jumped into the low 70s as an outflow came in on north-northeast winds! The NAM persists in keeping a remnant 500 mb vorticity maxima from TS Don and brings it to the southeast corner of Arizona today - with a substantial increase in rain chances (see morning NAM precipitation forecast ending at midnight tonight, just above the TWC sounding). The U of A Atmo WRF-GFS model appeared to have initialization problems this morning, so it's hard to compare with NAM today, as it blows up storms in local area by noon and runs them off toward the north-central mountains. The NAM forecasts the strongest 500 mb vorticity maxima over the Southwest to move right up the GoC today - will beinteresting to see if this actually occurs (there is a large morning MCS at the lower end of GoC).

Finally, TD 5E has formed off the south Mexican coast - forecast by NHC to become a hurricane but to stay fairly far southwest of Baja.