Wednesday, December 31, 2014

Brief Look At The Coming Storm


Shown above is a surface plot from a bit before 7 am MST this morning of the last day of 2014. New Mexico is covered with arctic air that is just sneaking briefly into southeast edge of Arizona. But arctic air on west side of Continental Divide is pushing steadily southward. There is precipitation across the northwest half of the state with Kingman reporting moderate snow and Phoenix Sky Harbor moderate rain. Still very dry here in Tucson area with 12 UTC morning sounding showing only 6 mm of PW. The CIRA blended PW analysis for 6 am MST (below) indicates that PW has increased to over half an inch in the northern GoC, with winds in low levels bring some of that our way.



The early run of the WRF-NAM at Atmo continues to forecast rapidly changing conditions here in eastern Pima County, as the shower bands and cold front move quickly by later today. The forecast skew-T above for TWC is valid at 1 pm MST - this sounding has the max PW forecast here by the model, peaking a bit over 6/10 of an inch. Moisture reaches to 600 mb, with a bit of CAPE below. Freezing level is very low, so some showers of graupel are perhaps possible.

The forecast below from the model is of total precipitation through 10 pm MST tonight - the shower bands are completely east of metro Tucson by that time. Model forecasts 2/10 of an inch at airport (or perhaps that point is TWC?) with some parts of metro area around 1/2 inch. Mt. Lemmon area comes in over an inch, which would be around a foot of snow. So, we're in for a quick-hitting winter storm as the New Year comes in with a blast.


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