Thursday, June 28, 2018

Moisture Increasing Slowly

This morning dewpoints have increased into the 50s F from Tucson southeastward - helped by mountain thunderstorms over northeast Sonora. Increases were gradual, except at Douglas where there appeared to be an outflow passage around 6:00 am MST. The CG flash density maps (24-hours ending at 12 UTC this morning - from and Vaisala) for the Southwest (above) and Mexico (below) show that Mexico was VERY active yesterday south of 28 degrees north. The Southwest was totally suppressed west of the Continental Divide.

Since the height analysis at 500 mb is not very enlightening, I took time out this morning to do a streamline analysis for that level. Results are above. the anticyclone has shifted off to the northeast, while Arizona remains between the California trough and the west part of the anticyclone. A weak, inverted trough extends from northern Mexico up into Oklahoma. There is a pocket of temperatures around and slightly colder than -8 C over much of Arizona. The extent of moist air (green) at 500 mb is uncertain because of the huge observational data void of northwest Mexico - but the IR image below (14 UTC) indicates that  the moist air at 500 mb probably extends from south end of GoC northward across much of Arizona.

Tropical storm Emilia is far southwest of the end of Baja and is forecast to move away toward the west-northwest.

Even though PW increases, the 06 UTC run of the WRF-GFS forecasts little rainfall (second below) over Arizona (except for places in Cochise County) through noon on the first of July - probably due to intruding westerlies from California and warming in mid-levels.

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