Models Forecast Huge Changes Next 12 to 24 Hours

At 500 mb this morning (above from SPC) gradual changes continue. There is now a weak anticyclone centered over eastern New Mexico. Winds are light and temperatures are warm to very warm, as per the -1 C at Amarillo, Texas. The IT of last several days has essentially sheared apart, with a bit of it remaining over south end of GoC. The pattern is better-defined at 250 mb (below also from SPC), with a distinct anticyclone over New Mexico. The jetstreak over the Great Basin will act to pull southern part of the western trough across Arizona tomorrow.

It appears that we will have a brief period of classic monsoon conditions next 18 to 24 hour, and then a change to Fall transition conditions with a westerly trough interacting with subtropical moisture.

The TWC skew-T plot (from SPC) above is little changed from last several mornings, with a bit of a moisture increase showing up in PW values. There is little CAPE this morning due to the ward temperatures above 500 mb and associated strong inversion.

I have looked at the WRF-RR for 12 UTC this morning and grabbed a couple of forecast soundings for TWC. Plot above is for 5:00 pm MST this afternoon. Model forecasts wind field to become better organized above 700 mb - PW is at 34 mm and mixed layer CAPE is about 350 J/Kg. However, very substantial outflow lift would be required to lift the BL air to its level of free convection (LFC).

But, the model forecast sounding for Sonoita indicates deep convection underway in that area by 5:00 pm. Strong storms to our southeast may generate an outflow into metro area this evening. This would further elevate PW, and perhaps have some chance of forcing deep convection. The TWC sounding forecast develops elevated, midlevel CAPE after midnight, indicating some chance of early morning storms.

All of the various versions of WRF model forecast a very active transition storm day tomorrow as short wave moves across southern Arizona. Forecast skew-T below is for TWC at 7:30 pm tomorrow evening - PW up to 49 mm with mixed layer CAPE over 1000 J/Kg. Possible severe storms and heavy rains indicated by model forecasts. Of course much of what the potential is tomorrow will depend upon how convection evolves later today and through the night. Certainly an interesting weather situation evolving, with much to watch.