Wednesday, November 08, 2017

Light Rains Over Southeastern Arizona

Clear, cool, and rain-washed air made for perfect walking conditions at sunrise today - 7:00 am MST view of Catalinas from campus above.

Models had locked onto this event by the weekend, and it evolved pretty much as forecast - the WRF model was too wet for some reason yesterday.  Amounts ranged from a Trace up to around a quarter of an inch - with heavier amounts south and east of us. The metro area got generally less than a tenth of an inch - above ALERT rainfall through 6:00 am. We had 0.05", which is first rain here since September 7th. Barely enough to dampen the ground along my walk, and definitely not enough to make a dent in what seems to me a fairly significant drought that has continued since mid-August.

Below, from NWS web page, is a broader map of rain reports from southeast Arizona. Presumably the colored underlay is radar estimated rainfall - but there is no legend or color bar. The radar's terrain blockage problems are clear, as are the problems of radar-only rain estimation. Note that many stations under the heavier yellow colors appear to have had no rainfall. This is due to the base/hybrid radar scan getting into the ice layers in the clouds, i,e., combined problems due to blockage, range, and the precipitation algorithm.

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