Snowy dustings, arctic express arrives Saturday

Let's face it, it's been an easy winter so far. We're living through more of a Kansas City, Mo.,  or Tulsa, Okla., winter so far in the Twin Cities. The numbers tell the tale.

• +6.7 degrees temps vs. average in January so far at Minneapolis-St. Paul International Airport

• +10.5 temps vs average in December at MSP

• +7.6 degrees temps vs. average in November at MSP

• 0 number of sub-zero hours in the Twin Cities this winter

• 8 number of sub-zero days on average by this point in winter at MSP

It's amazing how well forecasters have nailed the signal of our warm El Nino winter so far in advance. I remember in 1997 when I did a series of stories called "The El Nino Factor" during my first year as chief meteorologist at the ABC affiliate in Tucson, Ariz.

Climate forecasting was seemingly in it's infancy. A seasonal forecast predicting heavy winter rains in the desert and deep mountain snows? Talk about crawling out on a seriously shaky forecast limb. The series won first place in Associated Press awards the next spring after the forecast for a very wet winter panned out perfectly. "Groundbreaking" one of the judges told me.

Today it's almost a given that strong El Ninos will drive milder winters in the Midwest and northern states.

Progress.

A stripe of light snow advances through southern Minnesota  this afternoon. The main snow wave reaches the Twin Cities after 3 p.m., sometime during evening rush. With temperatures hovering close to the freezing mark many roads will be just wet, with some slick spots possible this evening.

A second system pushes north toward Chicago Friday throwing another light snow shot into Minnesota.

Arctic attack Saturday

The season's first true window-rattling arctic front barrels south through Minnesota Friday night. Temperatures fall through the teens Saturday, and approach the zero mark by late Saturday night. High struggle to reach zero form the Twin Cities north Sunday.

The latest European Centre for Medium-Range Weather Forecasts model coughs out a high of -7 Sunday in the metro. The National Oceanic and Atmospheric Administration's Global Forecast System model is a little more moderate with a high of +2 degrees Sunday afternoon.

Either way, you'll recall what the word winter means around these parts Sunday. Outdoor football anyone?

Winter's coldest...so far

Certainty that this air mass will be the coldest air mass of winter so far? 100 percent. Coldest of winter overall?

Maybe. Some meteorologists have tossed out bold predictions in the past like predicting no more 90 degree summer days in late July, only to watch as seven more days of 90+ degrees arrive just in time for the Minnesota State Fair. Thanks for that real shot in the arm for the credibility of our profession.

Suffice to say this will be the coldest air mass so far, and maybe the coldest of winter. February can deliver more sub-zero shots. The European Centre model is the most aggressive with the inbound cold wave. The "Euro" often handles arctic outbreaks better than NOAA's GFS.

The notion of four to five sub-zero mornings in the metro next week seems reasonable to this forecaster.

Lows between -10 to -15 also seem possible for the bottom next week in the metro, with -30 up north a good bet. The European model's notion of -19 next Thursday morning at MSP is eye opening. It's been exceedingly difficult to reach the -20 mark in the Twin Cities in recent winters. Wouldn't it be ironic to challenge -20 in a mild El Nino winter?

Milder after January 20?

Meteorologists watch the so called arctic oscillation for clues to longer range temperatures trends. The strongly negative AO forecast next week usually brings winter cold to Minnesota. A more positive AO arrives after Jan. 20 and temperatures are likely to rebound to more seasonal levels by then.

The notion of milder temps, even a potential January thaw starting around Jan. 20 fits with the longer term forecast model trends.

Stay tuned.