“Aug-tember” weekend; “Dual Pol’s” 1st test; Are forecasters legally responsible?

70s in most of MN this weekend – typical highs for early September

Warming trend early next week…80s return

Wet & thundery start?– for opening weekend of MN State Fair next weekend?

“Dual Pol” gets 1st test from Wednesday’s hailstorm in Stevens County

Sue Me – Belgian city wants to sue private forecast firm for “pessimistic” summer outlook

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Source: Twin Cities NWS

Weekend Forecast: Feels more like Labor Day

This should be a pretty nice weekend to get outside in Minnesota. The sweaty 90 to 100 degree days of July are out. In are cooler, comfortable, September-like days in the 70s this weekend.

While I can’t rule out a few spotty “instability showers” this weekend, most of the weekend hours should be dry.

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Source: Twin Cities NWS

High in the metro should hover in the mid 70s this weekend, about average for September 10th.

Warming trend next week:

Monday through Wednesday of next week look warmer, and probably dry. Minnesota will ride the back side of high pressure, and southwest winds will favor warmer breezes, and a return to the upper 70s and 80s Monday through Wednesday.

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Source: Iowa State University

State fair 2012: Mostly tasty with a chance?

Prediction: It’s going to be a good year to eat yourself silly at the 2012 Minnesota State Fair.

That said the GFS is still hinting at a low pressure system sliding through Minnesota Thursday & Friday, the opening 2 days of the fair. Latest trends point to a warm, and possibly thudnery Thursday, followed by a cooler wetter Friday.

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Source: ISU

Temps may warm again the following week….then trends suggest a cooler air mass nosing in from Canada for Labor Day weekend.

Overall the CPC outlooks favor a wetter than average pattern for the 12 day Fair run.

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Source: NOAA/CPC

Keep in mind that this is a long range outlook, and they are little better than 50% accuracy at 5-7 days. This outlook can, and probably will, change. Don’t bet the farm on my forecast, or anything else that far out.

I can almost smell the roasted corn and Sweet Martha’s Cookies drifting over the weather lab now. (By the way, who do we have to bribe to get the Milk Booth moved next door to Sweet Martha’s Cookies anyway?)

Twin Cities NWS “Dual Pol” passes 1st test: Large hail in Swift County

The good folks at Twin Cities NWS seem pretty pleased after trotting out the new “Dual Polarization” doppler upgrade for the first time Wednesday.

The radar seemed to do a pretty good job gauging the large hail in cells in Swift County Wednesday afternoon.

The details from Twin Cities NWS:

The late afternoon of August 15th gave us the first opportunity to see the dual pol products in action during a severe thunderstorm as a strong cold front moving across the Dakotas that afternoon generated a very strong cell over eastern Traverse County that moved into northwest Stevens County, where it produced large hail west of the town of Donnelly. We received two hail reports that evening from northwest Stevens County:

0535 PM HAIL 3 W DONNELLY 45.70N 96.07W 08/15/2012 M1.75″(golf ball)



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Source: Twin Cities NWS

Based on all of this information, the National Weather Service in the Twin Cities was able to issue an update to the active severe thunderstorm warning at 535 pm that mentioned the potential for tennis ball size hail with this storm. Although golf ball size hail was the largest hail reported, this spotter likely just missed the brunt of the hail core, where larger stones were likely falling. However, due to the sparse population of the part of Stevens County this hail core went over, we were unable to receive any hail reports from within the heart of this hail core. The remnants of this core eventually worked into northern sections of Morris, but by then the storm had weakened enough so that the largest hail being reported was only about the size of a quarter in diameter (1 inch).

The new Dual Pol also picked up an interesting feature called a “hail spike.” Here’s the lowdown from the Twin Cities NWS.

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Source: Twin Cities NWS

In the radar images above, a long hail spike could be seen extending down radial from the hail core west of Donnelly, MN. In a nutshell here is what causes these spikes:

1. Energy from the radar intercepts a hail core

2. This energy is scattered in all directions by the hail core (energy coming straight back to the radar resulted in reflectivity values greater than 65 dBZ)

3. Some of the energy scattered by the hail core is scattered down to the ground

4. The ground then scatters some of this energy back to the hail core, which then scatters it back to the radar

5. The time delay in going from hail to ground and ground to hail back to the radar gives the radar the impression that this energy came from something farther from the radar

6. Repeat steps 3 and 4 several times and you end up with a long reflectivity spike as seen in this example

Hail spikes begin to become common within Doppler radar imagery when the size of hail approaches and exceed 2 inches in diameter.

We’ll be learning more about how to best use Dual Pol in the coming weeks and months. One area that may help us this winter is to see how well DP is able to discriminate between rain/ice/snow in winter.

Stay tuned.

Belgian town may sue over “pessimistic” seasonal forecast:

Yes we live in a litigious society, but this may be a bit over the top.

The mayor of one Belgian town want to sue a private forecast over what he calls a pessimistic seasonal forecast. NPR has the story.

The mayor of the Belgian seaside resort of Knokke says it’s a crime that tourism there is down this year. He means that literally.

Leo Lippens wants to sue the private weather service Meteo Belgique for issuing a pessimistic full-summer forecast that he says wasn’t “fair” because it didn’t emphasize that the Belgian coast generally has clearer weather than the rest of the country.

“We all know we’re not in the Cote d’Azur or southern Italy,” he says. “But we have a fantastic climate here and to give the impression it is disgusting is disgusting and that I don’t allow.”

The private meteorological service forecast a while back that Belgium would have only two weeks of sunny weather in August.

Let’s be honest, the weather was brutally cold and wet in most of northern Europe for most of the summer, and only improved just in time for the Olympics in London.

This weekend a heat wave is building north into Europe. Here are the details from the BBC.


Source: BBC Weather

Are weather forecasters legally responsible for long range forecasts?

It’s a quiet weather day so if I may digress into a bit of a “weather editorial” here?

The “certainty” with which some meteorologists and forecast firms issue longer range and seasonal forecast is a problem in my opinion.

It brings back memories of Accuweather’s blaringly inaccurate headlines last winter touting a burtal winter of cold and snow in the Midwest. Here’s a (painfully inaccurate) excerpt:

In terms of both snow and cold, this winter is expected to be the worst in Chicago.

AccuWeather.com Long-Range Meteorologist Josh Nagelberg even went so far as to say, “People in Chicago are going to want to move after this winter.”

However, for the worst of winter’s cold alone, the AccuWeather.com Long-Range Forecasting Team points to Minneapolis.

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Source: Accuweather


These kind of “certain” declarations about seasonal forecasts, or inaccurate predictions of major snowstorms a week in advance or consecutive days of 90 degree heat a week ahead of time are “meteorological malpractice” in my opinion.

It’s like doctor attempting a surgery he has no tools for, and telling the patient he can pull it off with ease. If the people who issue these kinds of forecasts were doctors or lawyers, they would lose their medical license or be disbarred.

The state of the science of meteorology just is not refined enough to make such declarations…and meteorologists who issue such forecasts make all of us look bad, and mislead the public about the credible limits of meteorology.

I don’t mean to be sanctimonious here, and I get that this might sound that way. But I will admit this is a pet peeve of mine. I can be (have been, and will be again) as wrong as the next guy/gal about tomorrow’s forecast. But I’m very careful about making “certain” forecasts I know extend the limits of “credible” meteorology.

We work in a competitive business and I get that weather people want headlines…want to be the first, biggest, and best weather guy/gal they can be in their market. And some forecasters and firms in our business have a financial interest in promoting a certain narrative or making forecasts that sound like “weather terrorism.” Having a financial interest in what you’re writing or “forecasting for headlines” may be many things, but it’s not journalism, and readers need to understand that. When some in our business walk that road, it makes all of us look worse, and hurts everyone’s credibility in a field where it’s already a challenge to be a credible source for weather information.

Okay…this is me stepping off my little weather soap box now.

One question raised by the Belgian story and seasonal forecasts like Accuweather’s last winter is; can you hold weather forecasters who make forecasts that outreach the capability of the current state of the science and forecast models legally responsible?

One of these days the courts may have something to say about that.

What do you think as a listener/reader & weather consumer?


  • Randy in Champliln


    Nice post. From a amateur weather junkie I have learned a lot over the last three years. The most important is that forecasting skill outside of 7 days is a crap shoot at best. So much depends on what happens over the ocean’s and quite frankly we don’t have the ability at this time to sample the air over vast amounts of water like we do over land. So forecasting beyond 7 days is equivalent to predicting when the next Twins home run will be, which field it will be hit to, and to which row and seat. Unfortunately that kind of accuracy is what most of the public want’s out of our forecasters, and that is a impossible task.

    As far as the forecast for the State Fair, I’m leaning a bit to the warmer side for the first weekend and maybe for the entire run. I will try to put out a state fair forecast on Sunday on the Minnesota forecaster site. If we do move to a more zonal flow or even a NW flow, I am seeing the possibility that the source region may much above normal.

    Wait a minute….did I just enter the twilight zone??? lol

    Good Luck Paul!!!

  • Mr. G.

    Your “weather soapbox” rant is spot on.

  • Lars

    Hi Paul,

    Your posts are so informative! So, maybe the radar should wear poloroid sunglasses to cut the glar!

    As for forecasting and journalism, everyone has a bias. Isn’t there a contest in the profession for the best forecasts? That would be really interesting.

    Also, I think weather forecasting is like financial or economic forecasting. People make predictions all over the map, but the good ones will rise to the top, and command a premium price. Your forecast for last winter was pretty good, although I must admit it ran against my emotions.

    Do you think malpractice should apply to the whole global warming/climate change debate? Governments are spending billions of dollars based on these predictions. What happens either way?