Thursday, December 01, 2016

Low Temperatures and Possible Rain Event

Yesterday the low temperatures, as per MesoWest observations, hit hard freeze levels well to the north of the Hard Freeze Warning area. Hard freeze temperatures occurred over the Las Cienegas grasslands, up the Santa Cruz Valley almost to airport, and over a northeast portion of the metro toward Redington Pass.

This morning high and middle clouds before sunrise kept temperatures a bit warmer - the web cam views from campus are at 7:00 am MST top and 8:00 am down at bottom. Low here at house was only 29 F today.

A closed, cold 500 mb low will be developing to our west today and tomorrow - 06 UTC WRF-GFS forecast above is valid at 8:00 pm tomorrow - and then moving southward into northern Sonora. As this happens, the model forecasts PW to increase from the east to the south with shower activity developing. The model forecasts a fairly significant precipitation event, especially in Cochise County. Forecast below is of total precipitation forecast by the GFS version of the model valid through 11:00 am on Sunday, December 4th.

However, the NAM version of the model is much drier for both the 06 and 12 UTC runs this morning - so the models present quite a coin toss for the Tucson metro area.

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