Snow in Tucson?

It could happen by tomorrow morning.  The National Weather Service has issued a Winter Storm Watch above 4,000 feet for this evening through 11am tomorrow.  Here’s what’s happening.

A cold front blew through last night with some moderate to heavy rainfall lasting through the night.  We are now on the cold, unsettled side of the storm.  Today’s forecast is for much cooler with the rain showery in nature.  Cold air has moved in aloft, so especially this afternoon when we get a little bit of heating (yes, we get some heating even on a cloudy day) the atmosphere will be pretty unstable.  That means the possibility of some thunderstorms forming.  With such cold temperatures above our heads, it won’t take much for some of those storms to drop small hail.  The winds aren’t as strong as yesterday, and they aren’t as warm.  Yesterday it was south winds gusting to 60+.  Today it’s southwesterly winds gusting to 30ish.

Then there’s tonight.  Another weaker storm is on the heals of the one exiting right now.  It is coming straight down from the Gulf of Alaska.  It’s a cold system that will drop snow levels to 3,500 feet by morning and probably lower at times.  The storm is moving through at night and in the morning hours, so that increases the chances of very low snow levels.  The National Weather Service isn’t putting snow depths on it yet, but there is a chance of some good snows in towns south and east of Tucson such as Tombstone, Sierra Vista, Benson, Wilcox and of course Oracle.

Here’s the fun part.  This storm could also bring some convective activity with it.  In other words, some thunder is possible.  Any thunder activity would drag colder air aloft down to lower elevations causing snow levels to drop.  Even without thundersnow, it will be possible to see snow falling in the Tucson Metro area and possibly sticking in places like Catalina,  Oro Valley, Vail and the Foothills.

We will know more by tomorrow morning.