Mixed sun & flakes this week; Bigger snow Monday? Era of low model confidence

Flakey Forecast

Welcome to the era of “low model confidence.”

Spring and fall can be tough times for weather forecast models…aka “numerical weather prediction.” (NWP)

Faster moving weather systems and bigger north-south temperature contrasts mean the models have a tougher job keeping pace. Model errors can increase this time of year, and that can leave us grasping at forecast straws.

Last week’s “Snowquester” turned “No-quester” for Washington D.C. was yet another example of a forecast gone awry by the U.S. forecast models. When NBC News is telling you it’s time to get a new weather computer, you might have a problem.

In this Updraft we track our chances for sunshine and snow this week, and look ahead to a potentially bigger storm next Monday.

Ugh. Is it April yet?

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Mixed sun & snow showers:

It is nice to see the sun out this morning at the weather lab.

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This week features some fast moving “minor” weather systems zipping overhead.

The result is some sunny peeks today, more sun tomorrow and some occasional bouts of snow showers in between.

Temps will gradually moderate by Thursday & Friday…it will feel better out there. Call me stubborn, but I think the models this week have overdone the snow and cold. I still think well see 40s likely by Friday, and maybe even as soon as Thursday.

I don’t see any major snows in sight this week…but a few bouts flurries and light snow are possible today & Wednesday night. It may be warm enough for a few rain showers Friday.

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Tracking Monday snow chances?

This is 6 days off, so be advised there is great uncertainty (hope?) the storm track could change.

But the Euro and GFS model suggest a decent snowmaker next Monday that could produce another “plowable” snow for the Twin Cities and southern Minnesota Monday.

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The models are cranking out up to .75″ liquid at temps cold enough for all snow…that would be a pile of snow if it actually happens.

Again it’s early and this may change…but that’s the way the maps read today.

Stay tuned for changes.

Era of “low model confidence”:

Some of our forecast models are having a tough go these days.

Last week’s “No-quester” for Washington D.C. left some serious egg on forecaster’s faces, and on the suite of U.S.NWP products.

I’ve talked multiple times with Cathy Wurzer and Tom Crann on MPR about why the European Model often generates superior forecast products when compared to NOAA’s forecast models.

Once again, “King Euro” (the ECMWF) outperformed the USA GFS & NAM models on a major weather system for the USA. This marks at least the 4th big system, (Isaac, Superstorm Sandy, the massive February Nor’easter snow storm) where the Euro has outdueled U.S. models on a major storm in the past few months.

NBC News caught on to the trend, and aired this story Friday.

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I talked with University of Washington Professor (and NWP expert) Cliff Mass at AMS in Austin, TX in January. Cliff has a closer look at the latest model failure. Here are some excerpts.


So let’s understand some of the failure modes. The U.S. NAM model, the main U.S. high resolution model, produced too much precipitation and so did the U.S. global GFS (but to a lesser extent). Guess what modeling system did far better than either? Yes, the European Center (ECMWF) model did a superior job. Importantly, it realistically predicted less precipitation than the U.S. models. The graphic of storm total precipitation below, provided courtesy of WeatherBell, Inc., shows DC getting about 1 inch in the ECMWF model and 1.7 inches in the U.S. GFS model. The U.S. NAM model produced even more.

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So as Cliff points out, going into the Snowquester there were big differences and uncertainty in model outputs…that were not well communicated to the public by broadcasters.


The screaming message in all of this (and I am leaving a lot out) was that there was HUGE uncertainty in this forecast, uncertainty that was not communicated to the public by my profession or the media. Would decision makers have sent government workers home or cancelled schools if they knew that the chances of a big snow were marginal? I don’t know….but they deserve to have had this information, and I believe they could have made better decisions.

As broadcast meteorologists it serves our listeners and viewers better to communicate forecast uncertainty when it’s there. That’s sometimes hard to do.

In this age of uber technology, people have come to (unreasonably) expect “perfection” from us as a profession. Sometimes we foster that unrealistic expectation by coming off as too confident about forecasts that have a large, often hidden degree of error.

Sometimes forecasters make declarative, certain sounding statements about longer range forecasts several days out that simply are not supported by the state of the science of meteorology.

The truth? Nobody’s that good. Not me, not anyone else you watch, listen to or read in your perusal of weather offerings. And the models we rely on are not giving us much help these days.

We need to do a better job of communicating uncertainty when it’s there in our forecasts, broadcasts and blog offerings.

PH

  • John O.

    //We need to do a better job of communicating uncertainty when it’s there in our forecasts, broadcasts and blog offerings.

    Weather has become as much entertainment as it is information. We watch personalities from a certain cable channel standing erect (or trying to)against hurricane-force winds, or the local television reporter standing on the shore, in a snowbank, etc.

    The tools have obviously improved over time, but it is a question of how those tools are used and how the data is interpreted. And presented.

  • Chris

    I get all the talk about the model differences. What did you do just a few years ago before the EU model? How about a few years before that when models were probably more an academic toy?

    Were there just more misses of a forecast? Would good old fashion paper based forecasting and skilled meteorologist interpreting the data predicted this storm? Are we now relying too much on the models and the skill of the forecaster been lost or at least diminished?

  • bobbydole

    Hello,

    Wasn’t there talk of 50′s next week? Last year on the 17 I had ran a half marathon, it was like 80 and humid, I’m so glad that we have a real march this year :)