Wednesday, October 07, 2015

Overview Yesterday And Today


Two photos of one of the last strong storms yesterday afternoon. Above is view from campus just after 4:00 pm MST, as storm is moving north onto the Catalinas. Photo below is from Ron Holle who was looking toward the north end of the Catalinas at about 4:30 pm - the two photos illustrate how rapidly the storms were moving yesterday, since views are of the same storm.



The plot above (from Vaisala and weather,graphics) shows CG flash density for the 24-hours ending at 1230 UTC this morning. Active storms over Tucson area and to our north. There were several reports of severe hail here in Tucson and also around Casa Grande.

The system turned out to be a more prolific rain producer than was anticipated. Essentially 100% of the ALERT stations recorded measurable rain during the 24-hours ending at 7:00 am. Here at the house the rain for that period was 0.42". Across the network there were 40 sites with over half an inch and 6 sites with over an inch. At lower elevations the 1.24" at Craycroft and Golf Links was notable.

The 500 mb analysis for 12 UTC this morning (below from NCAR RAL) shows the 500 mb closed low just off to our northwest, with the morning storms in its cold core and to the east. Models emphasize the morning storms as the low moves southward across eastern Pima County.



However, the morning sounding (above for 12 UTC from SPC) is quite unstable below 750 mb. If there is some sunshine later today, the models could be conservative again for this afternoon. below is current NAM 500 mb forecast valid at 12 UTC tomorrow morning, with the low moving northwestern Mexico. As the large-scale ridge amplifies at higher latitudes along the West Coast of US and Canada, the low is being forced south and westward. If it ends up west of Baja, it may well visit Arizona again next week.


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