Wednesday, November 30, 2016

Hard Freeze North Part City of Tucson


Above is web cam view of Grand Canyon this morning, looking west-northwest from the Yavapai Point Geology Museum - temperature at the Canyon South Rim fell to at least - 5 F. The NWS web site observations link is broken now for the third day, so details regarding lows at ASOS sites are sketchy this morning.

Here at the house we had a morning low of 23 F - a hard freeze for this part of the City along the Rillito. Other lows - TUS about 32 F and Douglas about 14 F. Sasabe RAWS hit 18 F, while Empire RAWS dropped to 21 F.

There were two freezes here during November - 32 F on the 18th and now 23 F on the 30th. Rainfall amounted to only 0.37 inches, which was near the median for my period of record.


The QPF plumes from the 00 UTC run of the GEFS ensemble models (above for TUS) illustrate how, at times, the ensembles can actually confuse the forecast, with different members forecasting rainfall on three different days through the 7th of December. Certainly no convergence or consensus at this time.

Meanwhile the 00 UTC WRF-GFS (on the 5.4 km grid, below) forecasts little precipitation for Arizona and northwestern Mexico through 5:00 pm MST on December 7th. Cold morning temperatures will prevail, but with little chance of rainfall here.


1 comment:

  1. Afternoon Bob: Had aclass today or I'd have shared a "potential fix" for you on the ASOS obs. I noticed the same issue up here in Phoenix. I noticed that if I added a K in front of the three letter identifier the data appeared. For example DVT to KDVT and data appeared. Hope this works for you. Had 1.24inches up here in November and still waiting for a frost. I'm just close enough to terrain to get gentle downslope drainage winds starting ~ midnight which tend to warm up the neighborhood ~5F or just enough to avoid frost. Adios, Jack

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