Dirty Ridge Gets Dirtier: NC-17 or XXX?

As discussed in an earlier post, we're presently under the influence of a "dirty ridge," a long-wave ridge with relatively low amplitude that allows moisture and upper-level troughs to spill over it so that we still see periods of clouds and snow.

For the most part, this is good news as the Wasatch desperately need a freshening up, but I'm thinking about upping the rating for this dirty ridge to NC-17 or even XXX.  Why?  Well, the latest NAM is bringing in periods of precipitation beginning on Sunday, but with 700 mb temperatures rising to near 0C by Sunday evening.

1800 UTC 14 Jan 2011 Initialized NAM Forecast
Valid 1500 UTC 16 Jan 2011 (8 AM MST Sunday)

1800 UTC 14 Jan 2011 Initialized NAM Forecast
Valid 0300 UTC 17 Jan 2011 (8 PM MST Sunday)

So, in the heart of January, the climatologically coldest time of the year in Utah, we are going to see a warm storm, with snow levels Sunday evening near or even above 8000 feet.