Friday, September 04, 2015

September 3rd - Widespread Rainfall For Southeast Arizona

The models forecasts got back on track yesterday as there was rainfall at almost all stations across southeast Arizona. While thunderstorm cores mostly avoided the metro area, an MCS developed nearly overhead bringing light to moderate, stratiform rain and rumbles of thunder for much of the afternoon. Above is view from campus at 4:00 pm MST looking toward the nearly obscured Catalinas. First below is an IR image from 2:30 pm and second below is the composite radar chart for 3:35 pm. It was very nice event, except for some spots that were hit by intense storm cores.

The plot of detected CG flashes (above from Vaisala and Atmo) for the 24-hours ending at 11:00 pm MST last night shows that activity was focused over the eastern 2/3 rds of Pima County and north into Pinal County. There was little activity over much of Cochise County.

The ALERT network had 100% of stations measuring rainfall - above is the metro-W sector for 24-hours ending at 5:00 am this morning and below is same for the metro-E sector. Over the main part of the City amounts were generally around a quarter to a half inch. Here at the house we had 0.31". There were six sites that reported over an inch, and these stations were off to the far east and west sides of the array. Rincon Creek at X-9 Ranch had 2.09" and Rancho Del Lago (1.8 miles northwest of Vail) reported 3.46" The time plot of the rainfall for that site at bottom shows most of the heavy rain fell with a storm core that hit between 1:30 and 2:30 pm. Off to the northwest side of the network Picture Rocks had 0.94" (above) and that fell before noon with the morning storms that stayed off to the west of the City. Outflow from those storms moved eastward across much of the City, converging with outflows from the south helping to force the wider rain event.

Today the 00 and 06 UTC runs of the WRF models at Atmo forecast minimal activity for this afternoon, which would be the most common scenario, following such a widespread, summer rainfall.

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