Icy AM rush then 1″ to 3″+ snow through tonight; Watching Monday storm potential

Blinking Weatherball

"Colors blinking by night and day say, precipitation's on the way!"

If you're old enough to get the reference, you would know that more snow is on the way.

For my younger readers, here's the story.

Back in the day, we're talking 1960s & '70s now, a local bank had a thing called the "Weatherball."

The big brightly lit dome over the bank building would flash, or change colors to reflect weather changes in the forecast. There were several locations in the Twin Cities that had "weather balls." (I always wondered... who flipped the switch to change the colors?)

Check out the classic, cheesy "Weather Ball" jingle.

KARE 11's John Croman wrote a nice piece on the Weather Ball a few years ago.

The Weather Ball is getting a work out these days, and blinking for ice and snow today.

Expect some potentially icy and dicey commutes.

40F high temp at MSP Thursday (1st 40F since Jan 18th)

-Latest Twin Cities radar loop

-Latest NWS advisories

Clipper #2: Icy AM mix trends to all snow later

Today's clipper looks stronger, and will produce an icy AM mix...which will transition to all snow later today.

A early AM mix of freezing rain and possible sleet greets commuters this morning.

It looks like we may see 2 separate shors of precip today. The early AM mix...then a break around midday, then all snow returns PM & evening.

Widespread totals in the 1" to 3"+ range in the metro seem likely by Friday evening, with the best chance for 3"+ in the north metro.Heavier snow of 3" to 6" is likley from the far north metro northward to St. Cloud, Mille Lacs and Rice Lake.

The European Model "meteogram" below lays out the hour by hour snowfall scenario Friday.

You'll notice the cooler breezes tonight as colder air pushes in for the weekend.

Quiet Weekend:

Saturday and most of Sunday look sunny, but colder with highs generally in the 20s across Minnesota.

Sunday Night & Monday snow: Track trending north - Upgraded Canadian GEM Model leads the way

The latest forecast trends with our incoming snow system Sunday night & Monday reflect a northward shift in the potential storm track.

This winter, Environment Canada (Canada's NOAA) significantly upgraded their numerical weather forecast models. The results were stunning, and the side by side model tests appear to have shown improvements that take decades to achieve.

Here's part of the statement from Evinviroment Canada.

MAJOR UPGRADE TO THE GLOBAL DETERMINISTIC PREDICTION SYSTEM GDPS-VERSION 3.0.0) AT THE CANADIAN METEOROLOGICAL CENTRE

ON WEDNESDAY FEBRUARY 13, 2013, STARTING WITH THE 1200 UTC RUN, THE CANADIAN METEOROLOGICAL CENTRE (CMC) OF THE METEOROLOGICAL SERVICE OF CANADA (MSC) WILL IMPLEMENT VERSION 3.0.0 OF ITS GLOBAL DETERMINISTIC PREDICTION SYSTEM (GDPS), HEREAFTER REFERRED TO AS GDPS-3.0.0. THE MAIN CHANGES OF THIS UPDATE ARE:

- CHANGES TO THE 4D-VAR DATA ASSIMILATION SYSTEM: - THE USE OF ADDITIONAL REMOTE SENSING DATA: - AN INCREASE IN HORIZONTAL RESOLUTION FROM 33 TO 25 KM: - IMPORTANT CHANGES IN THE GEM MODEL PHYSICS: - AND 1200 UTC RUNS NOW DONE TO 240 HOURS AS FOR 0000 UTC RUNS.

OBJECTIVE SCORES DONE IN DEVELOPMENT AND PARALLEL RUN PHASES SHOW IMPROVEMENTS IN THE FORECASTS WITH MOST METRICS THROUGHOUT MOST OF THE ATMOSPHERE, IN PARTICULAR OVER NORTH AMERICA IN WINTER. THESE IMPROVEMENTS ARE OF AN ORDER OF MAGNITUDE USUALLY SEEN ONLY ONCE IN A DECADE.

A SUBJECTIVE EVALUATION BY OPERATIONAL METEOROLOGISTS AT CMC CONFIRMED THOSE IMPROVEMENTS

.

The finer resolution and better model performance now makes the GEM a serious competitor to the often reliable European Model (ECMWF)

Live Weather Blogs has an interesting take on the changes.

Today the Canadians announced a MAJOR upgrade to their model. FIRST they now going to run it 2x a day out to 240 hours. Over the past several years they have not done that with the afternoon or 12 run .

SECOND the model resolution will improve significantly from 33KM to 25KM.

THIRD and the MOST important the entire model is being upgraded to the vastly superior 4DVAR system... just like the one used in the European model.

FOURTH the Canadian Met center review which is been pretty meticulous has showed a major increase the Canadians model accuracy and a significant lowering in its ROOT MEAN ERROR scores.

It will be very interesting to see the next few weeks or months if the Canadian model actually verifies the preliminary testing of significant improvement with the 4DVAR. It would not surprise me if the Canadian model moved into second place behind the European as the most reliable model.... Assuming the initial assessment from the Canadians is correct.

Here's the Canadian GEM forecast showing a weaker system tracking further north Monday.

In the past 24 hours, the GEM and Euro have shown a trend toward a more northward track on Monday's system, and a corresponding reduction in potential snowfall totals for the metro. NOAA's GFS model is playing catch up as usual, and now agrees with the northward track trend.

If modle trends are right, that would lay the heaviest snow band north of the metro from Alex through Brainerd, St. Cloud and Duluth.

The Twin Cities should still see snow...but we may not get in on the heaviest totals from this storm. The northward trend is causing many of the modles to back off on potential metro snowfall.

Between the two systems Friday & Monday, some areas should see a pile of snow. The GFS picks up on the general idea.

GFS Snowfall totals from 2 systems Friday & Monday

Image wxcaster.com

Track changes as the models try and grasp incoming systems is the reason we don't put specific "inches" on snowfall forecasts until about 24 hours before the storm. It's hard enough to try and nail snowfall 24 hours out...and pretty much impossible to be credible beyond that. Especially 3-4 days out.

For now the likeiest scenario is that we will see some potentially "plowable" snow Sunday night & Monday in the metro, with trends favoring the heaviest snow just north.

Regardless of eventual snowfall totals, high winds and colder air by Monday night look to make travel difficult.

Stay tuned as we follow potential storm track changes heading into the weekend.

PH