Very Moist Inverted Trough Approaching Today

First, it was very suppressed over southeast Arizona yesterday, as shown by the plot of CG lightning strikes detected during the 24-hours ending at 5 am MST this morning. Storms were active in the more moist air over central Pima and parts of Maricopa and Pinal Counties. Two ALERT sites show 0.04" this morning, otherwise there was no rainfall measured in the network.

The eastern Pacific is very active right now with numerous areas of deep convection still active at 5 am MST - IR image above. An MCS has moved over the northern GoC, which will help push low-level moisture northward across the border. Note also the extremely cold cloud tops with the MCS off of Cabo Corrientes.

Closer to us, the inverted trough that was moving across Mexico and Texas yesterday has split apart with one piece drifting northward over western Kansas, while the main portion of the IT is moving fairly rapidly across northern Mexico, extending into southern New Mexico and southeastern Arizona. A very large cloud mass is associated with this part of the IT - see visible image below from 7:15 am MST.

Performance of the WRF model at Atmo has been somewhat erratic the last few days. Both versions of the early run of the model forecast some storms over eastern Pima County, however both forecast strong to severe storms and heavy rains to occur to our west and southwest again today. Shown below is forecast rainfall through midnight tonight from the early WRF-GFS - some forecast amounts exceed three inches. This is out where the models bring in the strongest influx of GoC low-level air. The NAM version of the forecast is drier, but with the max in the same general area and with little rain at all over eastern Pima County.

Both models forecast fairly strong easterly low-level winds, which is not good, but they also forecast considerable sunshine during much of the afternoon (although the GFS version spreads a large anvil cloud and low-level outflow over Tucson from the southwest by 4 pm MST) with high temperatures reaching around 100 F. Precipitable water continues to increase during the forecasts. The forecast 6 pm MST soundings for Tucson, in both versions, would appear to be favorable for stronger, more organized thunderstorms than the models forecast locally. So, another day with many "ifs, ands, and buts."