20220725

 Previous Forecast

As expected, it was a rough day for the WRF runs, but out of the pile of crap, there was one good run.  Heavy precipitation did occur in places along the Rim and westward along I 40, as well as in western Pima County.  Isolated heavy rain fell in the Tucson area, too, as I saw one gauge in Oro Valley that had 3.5".

There was an impressive amount of lightning with these storms as well.

The 12Z WRFHRRR turned out to be a very accurate run.  It ran the Pima County storms up to near Phoenix, where they died out, and kept the Tucson area storms on or near the mountains.

Discussion

Wow, is there ever a large MCV spinning over western Pima County!  There is another up by Flagstaff and another near Demming.  Good luck with those WRF.  The 500mb map kinda resolved both Arizona circulations.  At the synoptic scale, a trough over the central and eastern CONUS has suppressed the ridge, with one center over the lower Mississippi valley and another off the coast of BC. Flow over Arizona is generally southeasterly, but temperatures are a warm -5 to -4C due to all the latent heat released from the storm activity.

The weak IT that has helped organize convection is located over western NM.  Another much larger closed cyclonic circulation is located over NE Mexico, and it's moving to the NW towards Arizona.  I saw this feature over the Gulf of Mexico yesterday and didn't think it would be a factor so soon.  The 300mb map shows it's already creating an area of difluence/divergence over Sonora/Chihuahua, which is moving our way.

PW is way up, especially in central and western Arizona.  Phoenix is around 52mm, and Yuma, 53mm.  SE Arizona is generally in the low 40s.  Three of the GPSMET stations I look at were knocked off the air this weekend.  The Tucson sounding looks much like it did yesterday as it's nearly saturated all the way up along with an extended skinny CAPE profile.  Surface-based CAPE is relatively high at 750 J/kg.  The winds are mainly southeasterly, but at least there are 10-15 knots of steering flow.  

Phoenix is similar.  Despite all the activity yesterday, with some heating and the approach of the upper IT, it is certainly possible for storms in and around Phoenix and Tucson later today and tonight.

Initializations

I'm presently surprised to see that all the morning initializations were able to initialize the MCVs and clouds.  They are not perfect, as all have the NM IT initialized in NW Chihuahua.  The 6Z WRFHRRR doesn't have enough clouds over central Arizona.  Considering the situation, not too bad.  Hopefully, there will be a better agreement between runs today.

Day 1

The anomalous 850mb cyclonic circulation hasn't moved since yesterday, and I'm not complaining!  It's responsible for continuing the intense surge of moisture into Arizona and far into southern California and even southern NV.  

PW is about as high as it gets here in Arizona, except for a tropical storm: an insane 50-55mm across the southwestern part of the state.  850mb dewpoints are from 13 to 16C!

There isn't much consistency between runs regarding the location of CAPE.  According to GOES CAPE, there isn't a lot around, and the 12Z WRFRR seems to have the better forecast this morning.  CAPE isn't very high, but that is to be expected with this airmass.  The one exception is eastern Pima County.

Of great interest is the approaching IT.  By early afternoon, it moves close enough to provide difluence and weak divergence.  It appears its influence is already being felt as there is an ongoing area of deep convection over the border between Sonora and Chihuahua.

So far, most signs point to an active day.  However, the old rule of the day after a busy day is usually down may be in effect.  The Tucson forecast Skew-T has a strong cap on top of the mixed layer this afternoon.

There is good agreement between runs as they all have deep convection, mainly over the higher terrain of SE Arizona and along the Rim/White Mountains this afternoon.

The situation is the same in Phoenix, as a strong cap is at the top of the mixed layer.

All the runs are consistent, forecasting activity for much of far eastern and southeastern Arizona into the evening.  However, a few runs do have some activity for Tucson this evening, so it's not out of the question a few storms could break through the cap.

A few runs also develop some early morning activity to the east of Phoenix.  It's pretty unlikely, but storms could fire at any time in this regime.

Once again, heavy rain is a significant threat.  It looks like eastern and far southeastern Arizona have the highest risk.

Day 2

Predictability in this time frame is poor.  The only thing I'll say is the moisture continues across the state, but not at such an extreme as today.