20220729

 Previous Forecast

Another day of crazy heavy rain for some areas of the state.   The Tucson and Phoenix areas had some activity, but itmainlyostly on the light side, with "light" now defined as <1".

In general, the forecasts didn't have enough precipitation.  The WRFGFS was especially bad in western Arizona.  It was another complex situation, so I'm not surprised.

Here's the 3-day QPE.  Now that's crazy.

Discussion

Moisture has decreased by about 5mm over the southern 1/2 of the state but is still very high.  In addition, an outflow enhanced Surge is underway as a small MCS moved across northern Sonora last night.  Moisture is increasing again over southwestern Arizona as PW is increasing at Yuma and Puerto Penasco.  Tucson's airmass is worked-over with only minimal CAPE.  Winds are quite strong from the SE, around 700mb.  This may be due to the passing of the MCV, which is north of Casa Grande.  It's going to take a fair amount of heating to get the sounding to recover.  

Since the sounding was taken, Phoenix has had some showers and weak storms, so it's not representative of the current condition according to GOES.  It has cleared a little over Phoenix, and some CAPE re GOES.

The 500mb pattern remains the same as a ridge dominates the western CONUS.  A broad IT continues to spin over Arizona and northern Sonora, with multiple MCVs, embedded.  

Another in a series of TUTTs is moving across Northern Mexico.  Once again, it will provide some forcing via upper divergence.

Initializations

The 6z runs had the central Arizona MCV initialized too strong and too far south.  It was over Tucson at 15Z.  The 12Z initializations were more accurate, except the WRFRR crashed after a few hours.  As usual, it also had too much deep convection within the run's first few hours.  So, it looks like the WRFHRR is the favored run.

Day 1

So much for the slight drying that was forecasted yesterday.  A shallow Surge continues to advect very high PW air into the state.

The forecast for improved steering flow appears to be coming true as, by early afternoon, southeasterly 600mb flow is quite strong over much of eastern Arizona.

CAPE continues to mostly be below 1000 J/kg for most of the state, unfortunately.  Far northern and southeastern Arizona appears to be the favored locations.  SE Arizona is also clear.

By mid-afternoon, storms are scattered about the mid and higher elevations of the state.

As always, some good and some bad with the Tucson forecast Skew-T.  CAPE is pretty good at around 900 J/kg, and the vertical wind profile is better due to good steering. The negatives are a weak inversion at the top of the mixed layer, plus quite a bit of subsidence warming above 500mb.

There is no consensus for Tucson.  The WRFHRRR moves storms r to Tucson, but they dissipate as they move into the valley.

The 9Z RR manages to move an area of storms into Tucson.  Unlikely, IMO, but Tucson is due.

It's unlikely anything will happen in Phoenix this evening as they are weakly capped, and CAPE is only around 800 J/kg.  More likely is some early morning activity again.

Day 2

Central and western Arizona remains very moist, with 850mb dewpoint temperatures from 13-16C.  However, dry air advection is underway over far SE Arizona and has set up a convergence zone in far eastern Pima and Pinal Counties.

CAPE is high for SW and SC Arizona, so activity should pick up significantly for those areas.

The WRFHRRR moves a line of storms from the higher terrain of far southcentral Arizona into the Phoenix area tomorrow evening.  It looks too good to be true, especially as most other runs don't have this much activity.