It was a wet day over most of the higher terrain of Arizona with a few areas of heavy rain. Phoenix ended up with some scattered evening thunderstorms, but Tucson did not as they were too worked over.
The model forecasts were all quite accurate except around Tucson. I was convinced Tucson was going to see significant precipitation again as all the runs were forecasting activity. A well-known rule is that the day following an active day is almost always a down day so it was a big mistake on my part to of ignored this rule.
Yesterday, lightning was much reduced as the air-mass was very tropical-like with saturated vertical profiles and low vertical velocities. It was sure active in NM though!
I've not looked too much at the lightning threat forecasts so I thought it would be good to see if they were forecasting lower flash rates. Below are the RADAR and lightning forecasts for yesterday evening and one can see that the storms over the Phoenix area had low flash rates, which was confirmed by both the NLDN and storm chasers, while the lightning flash rates were forecast to be higher in NM.
Discussion
The 500mb continues to be stagnant as a large anti-cyclone dominates the center and the eastern US and a weak trough continues over the western CONUS. Hurricane Hanna is about to move onshore over south Texas, It remains to be seen if it will have any impact on Arizona weather. Arizona flow continues to be mainly weak southerly and temperatures have increased by a degree or two. There is an upper-level trough over Sonora. Note that Chihuahua continues to be 30m or so too low and an anomalous closed low has been analyzed. The wind field doesn't support this height.
The Phoenix 12Z Skew-T tells the story for the lower deserts today, as it has the signature of a "worked over" atmosphere where the lowest layers are wet and cool while the layers above are dry and warm. Note the difference between surface CAPE and mixed layer CAPE. It's unlikely for much if any activity today and into the evening.
Initializations
Fewer clouds are present over eastern Arizona this morning. Generally, the model runs have too much cloud cover, and the 6Z NAM is especially bad. The 12Z RR looks to be the best and also has minimal PW errors. It's the favorite for today.
Day 1
PW is generally about the same or slightly lower. However, by mid-day, drier air moves in from the west with very dry 850mb air at Phoenix and decreasing 850mb dew-points over eastern Arizona. Damn west coast trough!
Not much to say today. A few isolated storms over the high country and far southeastern Arizona.
Day 2
The situation remains about the same tomorrow.
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