Weather Whiplash: Summery weekend daydream ends as wintery nightmare Monday

50F degree temp crash – from 70F to 20F in 36 hours from Saturday PM to Monday AM!

20F low at MSP Airport Monday AM

16F forecast at MSP Airport Tuesday AM

March 9th last time temps in the metro the metro dipped to 15F

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0.3″snowfall total at the weather lab in Deephaven Monday AM

November 18th average date of first 1″ snowfall in the metro

31.5% of the USA’s lower 48 states snow covered Monday

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11.8% of USA snow covered one year ago today

20″+ snow depth now just west of Lake Winnipeg

1st measureable snowfall of 2012-’13 winter in metro Monday AM

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Early season snow coating at Weather Lab Monday

Image: Paul Huttner-MPR News

Seasonal Confusion:

It’s as if we fell asleep in a warm summery daydream last weekend, and woke up in a bad wintery nightmare Monday.

Wasn’t I just cutting my grass and picking up the last of the leaves Saturday afternoon in a T-shirt? Was that really thunder…and tornadoes in the dark of night Saturday? And how the #%!! was I suddenly transported into mid-December on Monday morning’s commute?

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Our latest case of weather whiplash in Minnesota came fast and hard. Temps literally plummeted about 50 degrees in 36 hours from Saturday evening to Monday morning, with tornadoes and snow in between.

Why were the roads so bad Monday AM?

I’ve heard a lot of explanations today about the extremely icy roads and how the “flash freeze” of melting snow on the roadways was to blame.

No kidding?

When the forecast calls for light snow and temps in the 20s, any untreated roads are going to get icy. Simple law of physics.

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An articulated bus jackknifed on Cedar Street, just south of the State Capitol on Monday, blocking the roadway and backing up nearly a dozen buses on Martin Luther King Blvd. as the rush hour closed.

MPR Photo/Tim Nelson

Without blowing a weather gasket here, let me point out a few basic things that illustrate why today’s dangerous road conditions and accidents were easily avoidable.

-The real reason things got instantly icy & dicey Monday was that the roads were not pre-treated, and there was no residual salt or road chemicals on the pavement.

-The same light snowfalls under 0.5″ occur many times in mid-winter without serious incident when residual salt is on roadways.

-When you’re doing snow & ice operations for a major city it’s up to the Public Works Dept road supervisors to correctly interpret the forecast and the actual impacts on road conditions.

-Light snow was in NWS and other forecasts this weekend for Monday morning

-Temperatures were forecast to be in the 20s Monday AM

-It was clear that roadways had not been treated yet this fall. Most major roadways have in pavement sensors that give real time temperature and salinity readings

-Had the roads been pre-treated Monday AM the light snowfall would not have much impact and there would have been few incidents

I don’t mean to be too aggressive, but it troubles me when public works officials try and “blame the weather” for bad decisions about snow & ice operational decisions. The real questions that need to be asked about Monday’s commuter nightmare are.

-Who or what does MNDOT & City of Mpls/St. Paul use for operational weather support?

-What forecast data did they have Sunday evening about Monday AM?

-Why did they not pre-treat roads this morning?

I used to work for an operational weather forecast firm that provided operational snow & ice forecasts & warnings to the cities of Chicago, Milwaukee and dozens of other municipalities in the Midwest. Both ends of this relationship can be tough jobs at times, but good operational weather support saves cities millions each year and saves commuters lives and accidents.

Sometimes as meteorologists on duty we make mistakes in the forecast, and we have to own up to that.

But when the forecast info is good and poor operational decisions are made in spite of good weather forecast information, the least public works officals can do is to own up to the fact that they either ignored the forecast or made a bad staffing and deployment decision…and not blame a well forecast “flash freeze.”

C’mon guys.

Coldest temps in 8 months:

Our bracing shot of Canadian air is the coldest in 8 to 9 months, depending on how you count it.

Monday’s high struggled to the mid-20s. The last time we saw a high below 28F in the metro was February 11th when the mercury struggled to 21F at MSP Airport.

The forecast low of 16F Tuesday AM will be the coldest since March 9th when we bottomed out at 15F.

The early cold spell grips the entire Midwest.

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Early deep snow cover visible from space:

If early “winter” season weather patterns hold, I’m growing more confident about the potential for plenty of snow this winter.

Early storms have systematically dumped heavier snow further south from Canada into the Dakotas. There is now over 20″ of snow cover west of Lake Winnipeg.

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Monday’s NASA MODIS Terra high res satellite shot clearly shows the extent of snow cover, and the Black Hills and dark waters of the Missouri River are clearly visible in the snow pack.

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With 31.5% of the lower 48 USA states covered with snow, we’re off to a strong early start in snow cover. The deep and extensive snow pack to the north & west will modify air masses toward the colder as long as it stays in place.

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Some will melt in Minnesota and the Dakotas as a milder weather pattern takes hold later this week into Thanksgiving week.

Temps moderate this week:

Southerly winds will return to Minnesota by mid week. Milder air will push temps back into the 40s by Wednesday….and 50F is looking pretty likely this weekend from the metro south.

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Mild Thanksgiving?

As I said last week, the early look at Thanksgiving looks mild for Minnesota.

The overall weather pattern seems to favor sunshine and temps in the 50s Thanksgiving Day and Friday. The GFS is hinting at changes Saturday & Sunday of Thanksgiving weekend.

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Early indications suggest the potential for developing snow somewhere in Minnesota late in the Thanksgiving weekend.

As I said last week, weather patterns are notorious for rapid changes in late November.

Stay tuned!

PH

  • Pat M

    I would be willing to bet the Minneapolis just want to pay overtime on a holiday. You can thank Pawlenty for that.

  • Pat M

    That’s didn’t want to pay overtime. Page refresh issue.