20220701

Previous Forecast

 The WRF forecasts were fairly accurate, with most of the activity from Flagstaff to the White Mountains.  

Discussion

The overall pattern has not changed much. Southwesterly winds are still present over central and western Arizona. Mexican upper air data was missing this morning, so it's challenging to determine what is south of the border. There has been deep convection going in Sonora for most of the night, with some moving into far southeastern Arizona. Moisture continues to remain high over the eastern 1/3 of the state while drying has started in western Arizona, despite a shallow surge seen at Yuma.

Phoenix doesn't have much CAPE, and PW has decreased. Winds are also unfavorable, mainly light and from the southeast. Tucson is better and has quite a bit of elevated CAPE, which is partially responsible for the storms underway in that part of the state. Steering winds are mainly light and variable, but it has cleared up there over the past few hours, and with the disturbance in Cochise County, it seems to me that storms are likely later today.

Initializations

I was pleased to see that all the morning initializations were accurate regarding the clouds and probable MCV location. Most had showers and a few storms, except for the HRRR which didn't have quite enough activity. CAPE/moisture was initialized well. I don't see any significant problems. Thus runs should perform well.  

Day 1

Moisture advection continues into the state from an ongoing Gulf  Surge. PW remains quite high, and 850mb dewpoint temperatures are favorable at around 12C over southern Arizona.  

CAPE is generally low over most of the state, but it's around 1000 J/kg over far southern Arizona. This looks like the favored location for storms, some with heavy rain today.

Storms develop over the higher terrain of southeastern Arizona and from the Mogollon Rim to the White Mountains this afternoon. The problem with storms in Tucson is that steering flow is weak, and storms aren't going to move much.  

It could go either way for the Tucson valley. CAPE is more than sufficient, at around 500-900 J/kg, and there is a deep NW moist flow due to the Surge, but steering flow is light and variable. Another problem will be anvils blowing over the valley from earlier higher elevation storms. Sorry to say that no model runs have widespread activity for the Tucson valley. A few storms may manage to pop up, but most activity remains over the higher terrain.

Today's 12Z WRFHRR uses a different PBL and cloud microphysics configuration to increase the QPF amounts as the WRFHRRR is always the lowest.  I'm using the Milbrandt-Yau MP and the Bougeault Lacarrere PBL.  Testing over the past few days has shown that this configuration produces more accurate QPFs.

Below is the old and new configuration. We'll see tomorrow how well it performed.

Scattered weak activity continues into the late evening over southeastern Arizona, including the Tucson area.

Day 2

The drying trend continues in western Arizona, but moderate amounts of moisture remain over the rest of the state.  

CAPE is generally less than 1000 J/kg but is sufficient to support storms over the mid and high elevations.

Steering flow is expected to improve, and a few runs can move storms into the Tucson area tomorrow night. Don't bet the farm on this one, though!