The small S/W at 500 mb that was the focus of yesterday’s activity moved north further east than the NAM predicted and is over southwestern New Mexico this morning. The northward movement of this feature – combined with the onshore movement of the California cutoff – has realigned features at 500 mb. This morning there is one anticyclone center over the southern GoC and one over the eastern Colorado/New Mexico border. Arizona is now within the southwesterly flow regime around the cutoff low.
Dry low-level air is present over western Arizona; however clouds and light showers linger from Nogales into the Phoenix area. The upper-air charts and VAD winds indicate that drier air should spread eastward today and limit storm activity to the higher elevations of the state, basically east of Tucson to Flagstaff line. Both the Tucson and Phoenix soundings were modified by the cloud deck overhead. The Tucson sounding also had several superadiabatic layers that produced a false cooling in the layer from 520 mb to 450 mb.
The NAM forecast indicates that storm activity shuts down through the weekend, with anticyclone in southwest again pushed into northern Mexico, and the main lobe of 500 mb high pushed far to the east. A very large inverted trough (one of the few we’ve seen north of 20N this summer) is forecast to be moving westward across central Mexico over the weekend (see above 84-h NAM forecast), while the tail of the west coast trough is sheared off and left behind off the coast of southern California and northern Mexico. So, it appears that the larger-scale situation will again become very complicated as we start next week.
Finally, Tropical Storm Felicia was named by the NHC two days ago and was forecast to remain a TS – but this morning she is a Category 4 hurricane. Too far away to be of interest to us, but folks in Hawaii are probably keeping a close eye on her.
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