Wednesday, October 24, 2018

Yet Another October Widespread Rain Event

Nice view of storms and anvils north of Kitt Peak a bit after 2:00 pm MST yesterday afternoon. Here in Tucson, the sun was shining on the Catalinas at 5:23 pm - bottom.

Flash density for CGs above for 24-hours ending at 6:30 am this morning (from and Vaisala). Most thunderstorm activity was in southeast and also central Arizona yesterday. There were 8 reports of storms producing severe hail (>1 inch diameter) yesterday and all were in Tucson or Phoenix areas.

The rainfall observations across the Pima County ALERT network are shown below for north portion (24-hours ending at 6:00 am this morning). Only one station near downtown did not measure at least 0.04". In the south portion of network Arivaca had 1.42", and the only other report of more than inch I found in quick scan of observations this morning was 1.16" at Douglas. There were 23 ALERT sites with half an inch or more. Here at house we ended up with 0.63". Most of that (0.53") fell in about 15 minutes with the mid-morning, intense thunderstorm, rest was with light showers from thick anvils through mid-afternoon.

Here at house we now have 3.25" for October, which is second wettest in past 20 years (but much less than the 5.06 of October 2000). This month is also much wetter than any other of 2018.

What are chances of a bit more before November? - long-range model forecasts indicate that the last day or so have at least slight possibilities. The GEFS 500 mb spaghetti plot above shows much variance among the various members over the Southwest. While the same deterministic forecast from the ECMWF below, indicates a closed low over Arizona. Both of these long-range forecasts are valid at 5:00 pm on Halloween.

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