Sunday, August 30, 2020

Today's Outlook

View of Catalinas about 9:00 am MST this morning - note how much cleaner the air is today, after yesterday's cleansing rains. This post will contrast two different WRF model runs.

The 12 UTC 500 mb chart today (above) is quite different than recent days. The anticyclone has been suppressed far to south near the northern end of Sinaloa. This leaves us under the influence of the west coast trough over central California - certainly not a great summer pattern. However, moisture remains high across southern Arizona.

The morning sounding (below) has reduced CAPE that is centered around 500 mb. Lowest levels are cooled by yesterday's rains and will only heat out to a shallow BL today. However, there is CAPE in the 850 to 700 mb layer that could come into play late today.

The 06 UTC GEFS plumes for QPF at the airport (above) are very aggressive for late tonight and again tomorrow night. Totals over an inch are highest I can remember in quite a long while.

Forecast above is from the 06 UTC WRF-GFS and is for composite radar echoes valid at 3:00 am early tomorrow morning. Strong storms are forecast from central Pima County eastward across the Tucson area. The forecast total rainfall at the airport through noon tomorrow from this model run (below) is a very heavy 2.8 inches.

However, the 12 UTC morning forecast from the WRF-NAM (above, valid at 5:00 am) has shifted the heavy activity eastward, but is still impacting the southeast part of our area. Total rainfall (below, through noon tomorrow) at the airport from this more recent model run is only a tenth of an inch, and the heaviest amounts are shifted into Cochise County.

A blend of the two forecasts would make for a very interesting night here in eastern Pima County. Time will tell - but, I'm hopeful for a better event tonight, since last evening's rain will barely keep the ground here at house damp until mid-afternoon.

If we do get another event here, it would be one of these rare occurrence of widespread rains on two consecutive days.

No comments:

Post a Comment