20220802

 Discussion

I was going to take another day off until I saw this-

Even the MLCAPE is an impressive 1977 J/kg.  There is plenty of bad with the sounding as anvil and steering winds are parallel.  Upper-level winds are also stronger, so anvils blowing out ahead of storms will be a problem for lower elevations.  The other issue is a reasonably pronounced cooling below 700mb and a cap.  Phoenix, meh.  CAPE is too low to support any activity unless the situation changes.

The 500mb anticyclone is centered over the NM/AZ border but is far enough north to allow southeasterly steering flow over southern Arizona.  It's very warm as temperatures are between -4 and -5, so this will inhibit deep convection somewhat.   There is a broad IT located in northcentral Mexico.

300mb is interesting as divergence/difluence is again present over NW Mexico and far southern Arizona as the same IT at 500mb extends to the upper troposphere.  This favorable situation will help enhance/organize any storms that manage to get going today.  WV imagery shows another IT moving westward from far southern Texas.

Initializations

Initializations are accurate for almost all locations (as it's mostly clear) except for one critical spot, far SE Arizona/SW NM.  Clouds and a few areas of precipitation are present, and none of the initializations were accurate.  Most had nothing except for the 6Z GFS and the 9Z RR, as at least they had scattered clouds.  The WRF runs mostly dissipated the clouds within a few hours after sunrise, which was too quick.   As the analyzed CAPE shows, this is today's hot spot for deep convection formation.

Day 1

A weak surge is underway by early afternoon, perhaps driven by the MCS in southern Sonora last night.  Hopefully, this will result in some decent low-level shear.

The surge signal is there at 850mb too, so it's quite deep.  850mb dewpoint temperatures continue to be very favorable at 12 to 14C.  

As seen on the sounding from Tucson, CAPE values are very impressive for parts of SE Arizona, including the Tucson area.

All runs generally agree that deep convection develops over the higher terrain east and south of Tucson by mid-afternoon.  As it's sunny there, I'd go along with that.  Plus, storms are likely to be triggered/enhanced by the little weak disturbance is, moving through eastern Cochise County.

Anvils are definitely going to be a problem for Tucson.  They are already moving in at 21:30z.

Anvil shading prevents any further heating, resulting in an insufficiently deep PBL.  The vertical wind profile is better, with some low-level shear and easterly steering and 1300 J/kg of CAPE, so the potential for storms is there but most likely, not realized.  Vail, Green Valley, or Oro Valley, places close to the mountains, might see a storm.

Quite a bit of storm activity develops over eastern Cochise County this evening.  I'm not 100% sure about this due to the cloud errors and uncertain amounts of heating.

Day 2

The Gulf Surge continues tomorrow, increasing moisture over much of southern Arizona.

CAPE is mostly moderate over southeastern Arizona and south of the Rim and the White Mountains, so it's expected to be an active day for those areas.

Some model runs have strong to severe storms for both the Tucson and Phoenix areas by late tomorrow afternoon or early evening.