PW Slowly Increasing

Quite a bit of middle cloud drifting around at sunrise today (see above), with some ACC far off to the north. The visible satellite imagery this morning (below) shows that significant cloudiness has pushed northward from Mexico into southern Arizona. The morning soundings reflect this and PW values are slowly increasing now, with amounts around 1.5 inches.

Both the early run of Atmo's WRF-GFS and the 12 UTC run of the NWS NAM indicate another suppressed day over the Tucson region - both models again forecast some storms to the east and south this afternoon. The 500 mb forecast by NAM for 5 pm this afternoon indicates a large, inverted trough extending from the south end of the GoC northward along the Arizona/New Mexico border (see below).

I have checked the North American analyses for this morning at the Univ. of Wyoming site - there does appear to be a trough in this region - as evidenced by both the sounindings in Mexico, and the widespread cloudiness. However, winds are very light compared to the afternoon forecast for 500 mb. So, whether or not some mountain storms (there appears to be increased CAPE today for high elevations) try to propagate off the mountains this afternoon depnds upon the strength of the  mid-level winds with the inverted trough. Winds at 200 mb are quite strong from the south, so storm anvils should stream off rapidly to the north. The morning 850 mb data indicate a fairly strong, low-level anticyclone over northwest Sonora - this favors gusty afternoon winds from the northwest here. But whether there will be increased moisture with this flow remains uncertain.
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Thus, some pros and cons for this afternoon - I think the models are probably a bit conservative today, and that there will be some increase in activity. The upper-level cyclone - see previous post - will be affecting our region by tomorrow evening, and both forecast models indicate a substantial increase in storms and rainfall as this feature approaches from the southeast.