Forty-some years ago analyzing an upper-air feature like this would have been more about art than data. Fortunately the experienced NCO forecasters who I worked with back then were incredibly perceptive artists. The main source of good data at that time was the FPS-77 radar at Davis-Monthan. The scant information on the upper air charts had to be finely analyzed to make sense of the situation. Now we have the Global Data Assimilation System, output available at a horizontal resolution of 0.25 degree (pixels roughly 25 km on a side), vertical resolution 50 mb or better, every six hours. Tucson is roughly near the center of the images below. The five 500-mbar images span the 24-hour period between midday yesterday and midday today. I haven't yet figured out how to make a loop. But anyway I think the evolution of this wave is best enjoyed one frame at a time.
A wind speed max at midday yesterday over extreme western Chihuahua was by early this morning anchoring the eastern side of a distinct trough, which was centered on an axis extending southwest-northeast through Arizona's Santa Cruz and Cochise Counties. Moderate precipitation was roughly aligned with the wind speed maxes, wrapped around the trough. Probably the evolution of the precipitation, and maybe of the trough itself, was tied to the availability of moisture. The images below show the precipitable water for midday yesterday and midday today. What was striking already yesterday was how the highest values of precipitable water, pegged out on the color bar at >1.7 inches, had pressed into the foothills of the mountains in east-central Sonora. Of significance for the coming days is that southwest New Mexico and northern Chihauhua have moistened since yesterday, even as central Chihuahua has dried.
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