Monday, August 13, 2018

A Metro Tucson Donut Hole Day

Storms on and north of Catalinas at 6:20 pm MST yesterday afternoon. During the day yesterday PW plunged significantly - reaching values around 30 mm before thunderstorms moved across portions of the metro area (time series of GPS-PW below from Atmo).

The classic Tucson donut hole is quite evident in the plot of detected CG flashes above - from Atmo and Vaisala for 24-hours ending at 1:00 am this morning. The ALERT map below (for 24-hours ending at 5:00 am this morning) presents a much diminished rainfall picture relative to Saturday. There was one heavy storm that moved westward from near Vail toward I-15. Here at house we had thunder, brief gusts to around 40 to 45 mph, but no rain at all.

Once again the Phoenix area was hit by severe thunderstorms with damaging winds and numerous reports of damage.

This morning skies are more clear across southern Arizona than they have been for many days - visible image above from 6:45 am this morning.

The strange large-scale pattern continues - above shows 12 UTC 500 mb analysis from SPC. An extended trough extends from south of Baja northward to a closed cyclonic circulation over eastern Colorado. The main anticyclonic circulation in West is over southern Utah, with heights now around 5900 m. The strong cyclonic circulation at 250 mb (the culprit that brought us the significant drying above the BL yesterday) has shifted well to northeast and is also over eastern Colorado.

The morning sounding has potential CAPE, but a new BL will be developing today and main question for afternoon will be whether a deep, well-mixed layer can set up with the very clear skies and abundant sunshine. The various WRF forecasts I looked at kept things quite suppressed locally. However, of additional interest is the strong gradient in PW across southern Arizona from east to west (below is MIMIC total PW analysis from 12 UTC this morning). Westerly flow in the BL could increase PW considerably during the afternoon. Many factors at play as the day evolves.

No comments:

Post a Comment