20190801

Previous Forecast
The activity was scattered across much of southern Arizona with some areas of heavy rain. Areas around central Arizona were mostly quiet due to the lack of heating and rain-cooled air. 

SE Tucson received heavy rain with over 2 inches.  I was also alerted to an extreme rain event in Portal from Mike Williams.  "The Visitor Info Center 1 mile away got 3.1", Cave Creek Ranch 3.25",  our house 3.4".  There wasn't anything even close to that reported by the MRMS Q3 product as much of the region has poor radar coverage.  However, radar echo tops were impressive as they were around 60k feet!

The model runs were pretty good with the best being the 15Z WRFRR and 12Z WRFGFS.  No forecast was able to correctly predict the storm that moved into SE Tucson though.

Initializations
Arizona is now under mid-level southwesterly flow with mainly clear skies. 

Initializations are generally accurate except PW was initialized too high over Arizona and into Sonora by all three models with the NAM being the worst, as usual.

Day 1
I wasn't going to bother with a discussion as I was confident nothing was going to happen today. However, after seeing the 12Z sounding from Tucson with 1500 J/kg of MLCAPE, I thought I'd better take a look.

850mb dew-points remain quite high into the afternoon and are more than enough to support storms.

CAPE is also forecast to be moderate to high, especially over far southeastern Arizona.

So saying all that, why do all the runs look like this?

Dry and warm air from 700 to 500mb is preventing any deep convection even for most higher elevations.  Another wasted high CAPE/moisture situation.

Day 2
Some drying takes place, but sufficient moisture remains over much of eastern Arizona for storms.

CAPE is again moderate to high over a large part of southeastern Arizona, so the potential is there for an active day.

500mb winds become a bit better as the 500mb high center moves a bit back to the west.  However, temperatures are high at around -5C so deep convection is again going to struggle.

The PBL is mixed deeply at Tucson by late afternoon.  The WRFRR doesn't have an inversion on top of the PBL, and along with much less dry mid-level air, there will likely be more storms around.  250mb winds are quite strong, so there may be issues for Tucson with anvil shading if storms form to the southeast.

There is a bit more activity compared to today, but that isn't saying much.

Not all hope is lost as storms develop by the early evening around southeastern Arizona. Some could be strong/severe due to high CAPE and a deeply mixed PBL.