20180705

Initializations

It’s going to be a challenging year for evaluating the model initializations because UCAR is no longer supporting its Suominet GPS IPW network. The website has been broken since March.  We are still getting the binary IPW data most of the time, but there have been some extended outages plus many stations are missing, especially in NW Mexico.  I am unable to determine if the sites are down or if there is a processing problem. In April, the upper air site at Empalme began to take data again but that lasted for only a short time and now it has been missing for more than 2 months.  Mazatlan Is also missing at 0 and 12Z. Chihuahua appears to be sending up a sonde only at 0Z thus at 12Z there is no data for all of NW Mexico. This is the worst upper air coverage in Mexico since I started writing these discussions 5 years ago.

There is a weak trough moving north through northern Arizona with some associated clouds.  The 500mb strong (5980m) high center continues to be centered over Colorado and there is a large anticyclonic circulation from south Texas all the way across the Gulf of Mexico with a secondary circulation over NE Mexico.  Model initializations look good for all features. PW initializations are mainly good for all of the 12Z initializations.

Day 1

Moist air continues to move westward into Arizona on strong low-level easterly flow around the strong low/mid level ridge and some moisture makes its way into western Arizona from the south.  

Easy come easy go.  The higher CAPE that was forecast to move across SE Arizona during the afternoon yesterday now appears to be insufficient to support any significant deep convection.  

About all that is expected are some showers and maybe a weak storm or two over south-central Arizona and into parts of SE Arizona later this afternoon and into the early evening.

There may be enough weak activity just to the east of Phoenix to send a weak outflow through the valley this evening, with a little “cooling” of around 5 degrees.  

Both Tucson and Phoenix become windy overnight with winds out of the east/southeast at 20-25mph.  The wind will keep the atmosphere well mixed and result in very warm overnight low temperatures.

At one point, it looked like Phoenix may set an all-time high low temperature but now that looks less likely. It is still going to be very warm though as lows are forecast to be around 94-95.

Day 2

Moisture advection from the east continues and it is quite wet over western Arizona.  However, drier air is moving into SE Arizona.

This drier air and downslope winds results in only limited CAPE except for the higher terrain of the Rim/White mountains and over into northwestern Arizona.

Some storms do develop out that way during the afternoon hours while the rest of the state remains mainly quiet.