20190904

Previous Forecast
Another mainly down day except for a few spots, like the Catalina Foothills.  A few storms made a run for Phoenix from the southeast,  yesterday evening.

Model forecasts were pretty good, and a bunch had the small storm that moved into the Catalina Foothills.  Forecasts had thunderstorms a bit too far north in central/western Pima County verified, unfortunately, by Mike Olbinski.

Initializations
The 500mb anticyclone center has expanded eastward, and the ridge covers much of the central and western CONUS.  Arizona is in mainly favorable southeasterly flow, but temperatures are quite warm, around -4 to -6C.   Bob Maddox pointed out in his discussion that there is an upper-level inverted trough over far northern Sonora.  The 300mb plot indicates southern Arizona is in an area of upper divergence/difluence.  Other than that, there was nothing of note.  All initializations look accurate, even the NAM PW.

Day 1
Based on the forecasts from yesterday, I didn't think I needed to write a discussion as it looked like it was going to be a quiet day.   That may not be the case due to the backdoor dryline, lurking moisture from around Phoenix westward, and the influence of the upper trough.  Low-level easterly flow has become quite strong and has really dried out eastern Arizona.  Surface dewpoints have fallen into the mid to upper 40s.

Some runs forecast quite a bit of CAPE for the moist areas.  However, the 15Z WRFRR is a bit drier so I can't say which is more accurate.  All Suominet sites for the Phoenix area and vicinity have been missing for weeks.  These sites are based on state  (ADOT?) GPS sensors.  Suominet doesn't have the manpower to track down the problem. 

Phoenix is deeply mixed by late afternoon and not far from the morning sounding LFC at 4500m.  With such a deep mixed layer,  some storms may produce strong winds.  CAPE is only marginal at around 400 J/kg.

Both the 12Z WRFRR and NAM develop scattered storms in and near the Phoenix area this evening.

15Z WRFRRx has storms mainly southwest and northwest of Phoenix.  It would be #sad if I wrote all this for just this.

Day 2
Moisture from Fernand does advect across far northern Mexico and into far southern NM and southeastern NM but appears to be insufficient for storms.  Dry air is over most of the rest of the state, resulting in very little activity.

#nonsoon2019.  I'm going to have to post some more astrophotos if this keeps up.