Thursday, July 03, 2014

Yesterday's Assessment Was A Flip-Flop

My assessment that rain was unlikely here at house, but wind and dust were probable, proved to be exactly backward - not a good start for me. I didn't look far enough out in the 12 UTC WRF-NAM forecasts yesterday to see that the model forecast a single storm across parts of the Tucson metro around 2 am MST - above forecast of composite radar echoes valid at 2 am. The 3 am regional radar composite from NCAR RAL is below - it shows a weak shower area moving into the north metro off the Catalinas. So, it appears that the 12 UTC WRF was best for metro area, but that the early midnight run was probably better for all of southeast Arizona. There was an outflow from the south that moved across parts of the metro area around 9 pm MST but gusts only reached 29 mph and T and Td changes were not very great.

The shower area made a direct hit on the house around 3 am or so. There was 0.06" in the gauge this morning and when I went out at 5 am it felt like a sauna. It was also a bit smelly - no wind, no lightning or thunder (see plot of CG flash detections through 5 am MST this morning - second below), and enough rain to just wet the sand and soil - there was only a slight smell of rain in the air, but with a horsey undertone drifting around from the ranches along the Rillito. 

No rain was reported at the airport or Davis Monthan or Atmo. There was only 1 of 93 ALERT stations that had rain and that was only 0.04" - the threshold amount, and other stations probably had measurable but lighter amounts. I've shown two plots of measured rainfall from MesoWest (Univ. of Utah products) here. Above is rainfall for the 12-hours ending at 7 am MST this morning. The house is right between the two reports in north Tucson. The 0.19" near Sierra Vista is from the Carr RAWS station. Art Douglas reports 0.48" at his location in Ash Canyon a bit to the south of the Carr site. Plot below is for 24-hour rainfall and shows a couple of amounts over half an inch.

So, a somewhat sputtering start to the summer storm season here in metro Tucson area - which isn't unusual at all.

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