Major Winter Storm moves into Upper Midwest by tonight
Blizzard Warnings in effect for most of Iowa & southern Wisconsin
Winter Storm Warnings include Albert Lea, Rochester, La Crosse & Winona
Dangerous travel conditions along I-35 south into Iowa and I-94 east into Wisconsin
10″ to 16″ snowfall totals in a Lamoni-Des Moines-Cedar Rapids-Dubuque-Tomah-Madison zone
5″ to 10″ snowfall totals for southeast Minnesota including Austin, Rochester & Winona
Metro on the edge of snow: Coating to 2″ possible favoring southeast metro?
40+ mph winds by Thursday
2 to 4 foot drifts in Iowa & Wisconsin
blizzard–A severe weather condition characterized by high winds and reduced visibilities due to falling or blowing snow. -AMS Glossary of Meteorology
The “Big One” for Iowa, southeast Minnesota & Wisconsin
The most serious storm in 2 years will dump over a foot of snow and bring blizzard conditions to much of the Upper Midwest through Thursday night.
Let me say this off the top…
**If you are planning any travel south along I-35 into Iowa or east along I-94 into central & southern Wisconsin tonight or Thursday you may want to reconsider or rearrange your plans. Expect near zero visibility winds to over 40 mph, severe blowing and drifting snow, falling temperatures and possible road closures.***
There aren’t many days when we would use the term “life-threatening” to describe weather in the Upper Midwest, but this is one of them. Again, there will be serious travel problems south & east of the Twin Cities in the next 48 hours.
Here’s the justifiably apocalyptic wording from La Crosse NWS.
URGENT – WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE LA CROSSE WI
403 AM CST WED DEC 19 2012
…DEVELOPING BLIZZARD TO BEGIN TONIGHT…
BLIZZARD CONDITIONS ARE EXPECTED TO DEVELOP FROM CENTRAL WISCONSIN INTO EASTERN IOWA TONIGHT INTO TOMORROW. HEAVY SNOWFALL WILL BEGIN THIS EVENING WITH WINDS STRENGTHENING TO 25 TO 40 MPH TOMORROW MORNING. THE HEAVIEST SNOW WILL FALL FROM CENTRAL WISCONSIN INTO EASTERN IOWA AND IS EXPECTED TO BE IN THE 10 TO 16 INCH RANGE BEFORE THE SNOW TAPERS OFF TOMORROW EVENING. DUE TO THE COMBINATION OF HEAVY SNOW AND STRONG WINDS…THE PREVIOUS WINTER STORM WARNING HAS BEEN UPGRADED TO A BLIZZARD WARNING.
A rapidly deepening low presure system tracking from Oklahoma to near Chicago.
The system has plenty of moisture to work with. The Gulf of Mexico is “wide open” and will feed moisture into this system. The system will also draw down cold air from the north on the backside. This combination will deepen the low, and produce a strong wind field that will whip snowfall into 2 to 4 foot drifts in eastern Iowa and Wisconsin Thursday.
You can see the evolution on this NAM model loop as the storm moves northeast.
We didn’t see many (any?) wrapped up storms like this last winter.
This storm will lay down a swath of prolific snowfall totals from eastern Colorado through Nebraska & Kansas into Iowa and Wisconsin.
10″ to 16″ snowfall totals will be common along this path.
Blizzard Warnings: 6pm tonight through 6pm Thursday
The increasing pressure gradient tonight & Thursday will kick winds into high gear as the storm rolls through. Sustained winds of 25 to 35mph and gust over 45mph are likely within the storm zone.
This will whip snowfall into 2 to 4 foot drifts and reduce visibility to near zero.
Blizzard conditions will be widespread with this system.
In case you’ve forgotten…here’s the full AMS Glossary definition of a “blizzard.”
blizzard–A severe weather condition characterized by high winds and reduced visibilities due to falling or blowing snow.
The U.S. National Weather Service specifies a wind of 30 knots (35 miles per hour) or greater, sufficient snow in the air to reduce visibility to less than 400 m (0.25 miles). Earlier definitions also included a condition of low temperatures, on the order of −7°C (20°F) or lower, or −12°C (10°F) or lower (severe blizzard). The name originated in the United States but it is also used in other countries. In the Antarctic the name is given to violent autumnal winds off the ice cap. In southeastern France, the cold north wind with snow is termed blizzard (see also boulbie). Similar storms in Russian Asia are the buran and purga. In popular usage in the United States and in England, the term is often used for any heavy snowstorm accompanied by strong winds.
Twin Cities on the edge:
Most of the models continue to keep the Twin Cities just on the northern edge of snow with this system.
Image: NAM snowfall via wxcaster.com
The GFS continues to be the “outlier” and predicts several hours of light snow sneaking into the metro from the south between midnight tonight to about 6 am Thursday.
The GFS still prints out about .18″ liquid for the metro, which the model translates into about 1.6″ of snow for MSP Airport. Again, this is the northernmost model solution, and the snowy edge will likely set up just south of or grazing the southeast metro overnight. But it will have to be watched for any slight northward shift.
This morning’s 12z NAM has caught onto the GFS trend of shifting the northern edge of snow into the metro tonight, and now prints out 2.4″ snowfall for MSP Airport.
At this point I am leaning toward a coating to as much as 2″ favoring the SE metro overnight.
The much bigger message with this system is, drive 90 minutes south or east of the Twin Cities and you’re going to be in full blown “winter storm” mode.
Boy Scout motto on this one…”Be prepared.”