More active day than anticipated yesterday for local area, especially higher elevations from north-east-south. There were 53 ALERT stations with rainfall during past 24-hours (58% areal coverage) - 12 sites had 1/2" or more and 4 sites had over 1". Greatest amount was near Arivaca in the far southwest corner of the network. Plot above shows the Catalina Mountains sector of the network, with high amounts extending from near the crest northward into Pinal County. Here at the house we had a very brief shower around 5 pm that produced 0.04" of rain - I didn't hear thunder, but there was lightning to the north and also to the west. Brisk easterly winds at sunrise - Mike Leuthold mentioned these yesterday, since they add an additional complication to the mix of weather ingredients this weekend.
The 6 am MST IR image below shows the cloud masses associated with TS Ivo - the Ivo circulation is large and La Paz, Mexico, at the south end of GoC, has south-southeasterly winds of 20 kt and greater from surface to above 300 mb. Precipitable water down there is nearly 60 mm. Note also that there was a morning MCS centered southeast of Douglas, Arizona. Outflows from this have keep low-levels cool and moist locally and helped to enhance the east winds.
The early WRF forecasts (both variants) went seriously awry early in the forecast cycle. Both the GFS and NAM versions forecast a pre-sunrise MCS centered over eastern Pima County. So, I have not looked at the runs in detail. The range of possible outcomes for the weekend continues to be substantial in the models. The above graphic shows total rainfall predicted for the 48-hours ending at 12 UTC Monday by this morning's NAM forecast, while the graphic below shows total rain ending ending at same time from the midnight GFS forecast. The NAM now forecasts heavy rain areas across most of Arizona, while the GFS continues to keep heaviest activity along the Colorado River Basin. I noted that the most unstable sounding this morning was that taken at Las Vegas, Nevada.
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