A DICEY "ICY" DAY FOR SOME...

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A DICEY "ICY" DAY FOR SOME...

What's shaping up to be a historic winter storm for Minnesota is coming together over the Midwest early Wednesday. While parts of that state may see as much as 25 inches of wind driven snow, my area will experience ice in the north and rain accompanied by a few thunderstorms across the south. A whole host of advisories are in effect for much of the Midwest north of I-80.

Specifically, the northern tier of my counties north of a line from Cedar Rapids to Freeport is under an ice storm warning. Further south, the rest of my region near and north of I-80 is under a winter weather advisory from Iowa City and the Quad Cities north.

The ice storm warning and winter weather advisory currently extend from 9:00am Wednesday to noon Thursday for freezing rain (perhaps mixed with sleet). The icing is not expected to develop until mid to late morning Wednesday and could be an issue for some into early Thursday. The critical ingredient will be temperatures which are projected to hover near of just below freezing through that period, especially in the area closer to HWY 20. Further south, readings may go just above freezing for a period or two which potentially alleviates some of the worst conditions south of HWY 30. A slight shift in the track could alter the freezing line and its impacts north or south in the coming 24 hours as the storm evolves and begins to show its hand.

Along with the ice, a real concern is the projected winds which could reach 35-40 mph out of the east southeast late Wednesday night. In spots that do experience significant glazing, scattered power outages are possible due to the winds, especially in the far north. Travel is likely to become hazardous in untreated areas, that includes sidewalks and driveways.

As you can see, the area in red up near HWY 20 is where ice accretion of 1/4 to perhaps 1/2 inch is expected. Further south in the yellow amounts of .01 to 1/4 of an inch are possible.

The latest modeling Tuesday night has shown a trend to shift the ice potential about a county to the south.That said, a degree or two could make a significant difference on the impacts of any icing suggesting the situation remains fluid and is one that needs to be watched as events unfold. Here's the latest guidance and what it suggests for ice accumulations. I have not included the GFS as it seems too far south on the depth of the cold air and most likely is misleading.

The EURO

The 3k NAM

The 12k NAM

The Canadian HRDPS

Further south, a moisture rich environment wil foster heavy rain where temperatures remain warmer and above the freezing mark. Thunderstorms are also on the table along with a slight risk of some excessive rains in my far southeastern counties into central Illinois.

At 500mb, you can see the strong southwesterly flow aloft that is forcing moisture rich air into the central U.S. Also note the massive ridge off the coast of Florida...very impressive.

You can also see in the satellite the coupled jet structure as the sub-tropical jet and its warm moist air attempts to phase with the cold air contained in the Polar jet to the northwest.

Water vapor levels are shown at 2 inches just north of St. Louis Wednesday afternoon. Juicy!

That amount of moisture is 500 percent of the norm for February 22nd. That's sic.

There is also enough instability for thunderstorms, especially over the southeast with K index values of 25-30.

SPC even has a slight severe thunderstorm risk posted for parts of Missouri and Illinois, just SE of my area Wednesday.

Here's what models are pointing to regarding rain totals for the event.

The EURO

The GFS

The Canadian HRDPS

The 3k NAM

The 12K NAM

By the way, if you are traveling to Minnesota or Wisconsin, a shut down winter storm is anticipated. The NWS in Minneapolis shows widespread snow totals of 15-21 inches in and around that region. They are calling it a historic snowstorm that could be a top 5 snow producer in Minneapolis.

The winter storm severity index indicates extreme impacts around the MSP metro with deep snow and near blizzard conditions thanks to 40 mph winds. Travel in much of Minnesota and central Wisconsin will be extremely dangerous or impossible and travel is not recommended. I would not travel north of HWY 20 late Wednesday and most likely into Thursday.

Once the system ejects Thursday morning windy and much colder air surges southeast and gets the weekend off to a frigid start Friday with wind chills of 5 below northwest to 5 above southeast.

The shot of cold air brief as temperature begin to moderate late Friday. In fact, the warm air advection brought on by the return of warmer air is likely to develop some light snow. The EURO shows minimal amounts.

The GFS is a little more robust with some amounts north of I-80 of 1.5 inches. Plenty of time to figure that out but for sure it won't be much more than an inconvenience and a reminder its still winter.

The incredibly energetic pattern continues into next week with another strong wet storm shown entering the region later Sunday night and Monday. The system takes a track that often would be golden for heavy snow in my area except for the fact there is no cold air to support it. It'sa good thing too as the GFS shows 1-2 inches of precipitation which at a 10:1 ratio would be 10-20 inches of snow. Dang!

I will close on this, the EURO 500mb jet stream structure March 8th. The red heights from Alaska to western Greenland indicates a blocking pattern consisting of high pressure that extends across Canada. The loading pattern includes a trough over the SW United States that will eject peices of energy into the nation. With the blocking to the north, these impulses will likely cut east across the country keeping things very active into mid March. I would expect above normal precipitation and while tempertures may end up close to normal, we'll likely see some pretty good swings with a set-up like that.

That concludes my discertation tonight. Be careful in the roads where ice is expected! Roll weather...TS