SE Arizona was very active as well as north of Phoenix. Most of the model runs got the SE Arizona activity, but only the WRFGFS was active enough in Yavapai county but was also way too active around Tucson and Phoenix. The various runs of the WRFRR seemed to be the least bad.
Initializations
Another complex morning with widespread clouds and scattered storms over central Arizona perhaps associated with a weak mid-level IT or from the approaching trough. The upper IT has stalled out over far northern Chihuahua and extends back into far south Texas. All three of the initializations had some clouds and developed showers and storms over the Phoenix area this morning. There seems to be some sort of moisture convergence going on there as the IPW has slowly increased overnight to above 50mm this morning. The initializations have a 700mb circulation over far NW Sonora which can be seen in the upper air data.
The GFS had the best precipitable water initialization. The other two were somewhat too west over northern Mexico.
Both the WRFNAM and WRFRR had the Phoenix convection forecast pretty well thus they might be the model runs of choice today. In any case, model confidence is only medium due to the complex situation.
Day 1
Impressive AM convection ongoing over Phoenix. No model run had a clue except for the 6Z WRFNAM as it had a few storms develop in the area after 12Z. For some odd reason, moisture did not decrease around Phoenix as it did just about everywhere else. By afternoon, 850mb dewpoints are moderate over most of the eastern two-thirds of the state. In general, moisture continues to slowly decrease over the state.
500mb flow is mainly from the south to southwest and has increased up to 20 knots in places. Thus storms should show a bit more organization today. (already happening in Phoenix!)
The upper IT continues to place weak difluence and areas of divergence over eastern and central Arizona and may be playing a part with the activity around Phoenix.
Eastern Arizona looks like the favored location as CAPE is highest there. CAPE is probably too high around Phoenix as morning convection was not quite right in the model runs.
Both the WRFNAM and RR move the ongoing strong deep convection to the NE and expand the coverage.
Precipitable water has been dropping around Tucson and is now less than 40mm. The WRFRR keeps IPW about the same this afternoon which results in only about 500 J/Kg of CAPE. Winds are mainly light with steering only about 10 knots from the south which isn't favorable for the Tucson area.
Only a few isolated storms are active during the late afternoon and into the evening.
Day 2
Much less moisture tomorrow which results in much less activity with only isolated storms over the high terrain of eastern Arizona.
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