Saturday, February 09, 2013

First Rain Band On Saturday AM

Am writing this at 7 am on Saturday morning, 9 February 2013. At this time the first rain band has moved on to the east of the house. Between about 5:30 and 6:45 am MST there was 0.07" of rain here, and I see that the snow level was very low on the foothills. I show two radar products here from the KIWA radar (these have come from the College of DuPage - CoD link to right - weather site). The top image is precipitation type at about 6:35 am - this is one of the products available from the dual polarization upgrade. The CoD radar page has many of these polarization products available, which is a real plus, since they are not shown at the NWS radar pages. Precipitation type indicated in the image is DS (dry snow). But wait, it was raining here. Unfortunately, the NWS KIWA radar is sited at over 5,000 ft MSL out in the Empire Mountains. So, the radar beam is always substantially above the low elevation locations here in the metro area, thus the radar indicates only snow. This illustrates one of the problems of siting the radars at high elevations (there is a separate set of problems that would occur were the radar down here in the low elevation areas).

The product below is the VAD winds aloft time-series, another product that can be examined at the CoD web page. This product shows the strong west-southwesterly winds aloft over eastern Pima County. Note that the lowest winds are obtained at 6,000 ft MSL. Regardless, the CoD site is one that I go to if I want to examine radar data in more detail than I can at the NWS web pages.

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