20190903

Previous Forecast
Another quiet day.  Most runs were accurate except for the WRFGFS which had too much activity.

Initializations
Not much has changed as the center of the 500mb anticyclone continues over the Four Corners.  -6 to -5 air is present from Tucson back into west Texas which can't be good for southern Arizona.  There is a weak IT over the southern Gulf of California.  Tropical depression 7 is moving onshore south of Brownsville, and Juliette is moving away from land, way southwest of southern Baja.  Neither are factors for Arizona.    Initial conditions look fine except the RR has a closed mid-level circulation over the southern GofC which seems too strong to me.  PW is fine except for the NAM's typical 5-8mm wet bias in NW Mexico.

Day 1
The 12Z Tucson sounding indicated that there was a bit more MLCAPE today at 800 J/kg.  Steering flow is again pretty good, but upper winds may blow anvils out ahead of storms.   Afternoon moisture isn't all that great as it's only 28-35mm in south-central Arizona.  Dry air continues on low-level easterlies for eastern Arizona.

It looks like another quiet day for most of the state.  There is enough CAPE to support storms over much of south-central Arizona though.

Maybe, maybe not for Tucson.  The convective boundary layer isn't mixed deeply at all and is going to need help for deep convection to form.  CAPE is sufficient and there is low-level shear, so maybe storms could move off the mountains into the lower elevations.

By late afternoon, some strong storms do manage to get going over parts of Pima and Santa Cruz county perhaps assisted by the back door dryline in the area.

There is a deep inverted V profile which may result in some very strong to isolated severe winds for the storms around Tucson.

Not much, if any, activity is expected for the Phoenix area as there are no nearby storms to provide any outflows to trigger storms.

Day 2
Dry easterly flow continues over eastern Arizona, so there won't be much activity there.  Much of western Arizona has some moisture and perhaps enough to support some scattered storms.

This doesn't look very good for much of the state.  There is just enough CAPE for a few storms for mainly the higher elevations.

There is some hope for the Phoenix area as the PBL is deeply mixed as well as some CAPE (ignore the surface-based, it's way too high).

The WRFRR does develop a few storms during the late afternoon/early evening.  Maybe even Yuma will see some activity as CAPE is very high.