Thursday, September 13, 2012

Fair Amount of Forecaster Variance for Weekend Temps


Actual weather: The official high temp at MSP for Saturday and Sunday was 85 and 80, respectively. Who was the best forecaster? Tough to say in this case. One conclusion is that most forecasters did not fully note the drop in temp between Saturday and Sunday. 

Friday update: As of Friday evening, KARE (locally) and Accuweather (nationally) continue to be on an island in predicting the coolest weather this weekend.

Will the weekend be quite warm or just pleasantly warm? There was a fair amount of spread among the forecasters as of Thursday evening for the Saturday/Sunday temperatures. Most shocking is that there’s a 7-degree difference in the forecast for Saturday, though it’s just 36 hours from this writing. In general, KARE is on the cool island for this weekend’s forecast while Weather Underground’s BestForecast is a clear outlier for Sunday’s forecast.



WCCO: 84/82 (Th), 84/88 (Fri)

KSTP: 82/82 (Th), 82/84 (Fri)

KMSP: 85/84 (Th), 83/85 (Fri)

KARE: 78/77 (Th), 80/80 (Fri)
Strib: 81/80 (Th), 82/83 (Fri)
NWS: 85/84 (Th), 82/84 (Fri)
Weather.com: 83/85 (Th), 84/83 (Fri)
Weather Underground BestForecast: 84/70 (Th), 84/88 (Fri)
Accuweather: 79/78 (Th), 80/78 (Fri)
Intellicast: 84/86 (Th), 85/84 (Fri)

34 comments:

  1. KARE 11 clearly is looking at the 12z NAM MOS guidance & taking it verbatim. Apparently they have not factored-in other circumstances such as extremely dry air & soil, past climatology from this summer and MOS deficiencies.

    It will be interesting to see how this evolves.

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  2. Not sure how in the hell WxUnderground comes up with a 70 for Sunday. Nothing points to this solution.

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  3. WxUnderground has since changed the Sunday forecast. Their "BestForecast" is still being refined. Can't apply the same "experimental" concept to KARE.

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  4. Kare's forecast is incredibly close to that of Accuweather's. Hmmmmmmmm...

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  5. Hopefully this is going to be the last post/thread on warm weather.........bring on the CHILL.......I see a few 50's next week! Yes

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  6. For the record, when I started visiting this site, I was expecting to see work in the vein of what Nate Silver over at the FiveThirtyEight blog wrote regarding weather forecasting, albeit with a local (Minnesota) flavor. I urge everyone to read it, including Bill.

    http://www.nytimes.com/2012/09/09/magazine/the-weatherman-is-not-a-moron.html?pagewanted=1&_r=2pagewanted=all

    --Kevin.

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    1. Kevin,
      You have made your point ad nauseum. I do what I do, and last time I checked, nobody was holding you at gunpoint to visit this site. Please, for the love of god, STOP VISITING THIS SITE if it causes you such consternation. And better than that, start the site you're dreaming about. I would gladly visit it, but I would have the courtesy and decency not to keep hounding you over and over about things I didn't like about it. I'm sorry this site isn't what you like; I'm just a person doing this on the side and having a little fun with it. I read FiveThirtyEight as well, and quite clearly the background and credentials of the author far dwarf my time and abilities.

      I have received numerous comments from visitors saying they enjoy this site for what it is. It gives them a place to share their thoughts with others and they enjoy seeing the comparisons I put together, though they may lack the sophistication you seek or even what I'd like to do if I had the resources.

      Let it be known that from here on out, I will delete any comment you make that is critical of me or this site. You are welcome to make comments about weather and forecasts like every other visitor, but I refuse to allow this site to sustain personal slams.

      Please stop visiting this site with your negative energy.

      Thank you.

      Delete
    2. Bill,
      I appreciate your site for what it is. Kevin, do us all a favor and get lost.
      John in Wayzata

      Delete
  7. Kevin, Bill tweeted that NY Times article a week ago. Your late to the party, and not a very nice guest either.

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  8. I apologize for reposting something that had already been covered. I stumbled across it today and thought folks here would appreciate reading it. It seems as though the did, as many have already seen it from the earlier tweet.

    Bill, I liked your mission statement when you started this site. I was intrigued to see what your findings would be. Several months ago you said you'd share what you've found and I have yet to see those details. Aside from that, several posters have offered help to make your analysis more robust. My frustration stems from most of your posts being negative comments against the weather forecasters based on the absolute bare minimum of effort from you. It seems that what started as an opportunity to investigate the quality of the local weather forecasts and determine if there was a bias toward more severe reporting devolved into you and others complaining about the forecasts. Very disappointing.

    I would still like to see the results of your investigations since I've been coming here from the start. The trend over the past six months is disheartening and I had hoped that you would reflect on the way things have gone. If not, that's okay. As you point out, it's your blog and you can do with it as you wish. If you want a blog where you can complain about the weather forecasts, you can do that. I would ask that you change the mission and title image of the blog to reflect the new mission. Alternatively, you could enlist some of the more prolific posters (Big Daddy, RandyinChamplin, Novak) to help you collect more forecasts and more data. That would be pretty slick, IMO!

    Again, I do appreciate the original mission of the blog. My tone of late is mainly a result of my frustration of the track the blog has taken in the past several months. In any case, I mean you no ill will, but would certainly appreciate a return to the original mission.

    --Kevin.

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    1. Thanks for clarifying Kevin. I've been meaning to post a blog about what I've learned over the last two years of doing this. The truth is that lacking sophisticated computer analysis and comprehensive data gathering skills, there's no way to truly asses forecaster performance. What I'm left with is: 1) analysis of snow forecasts (the easiest thing to assess), 2) the occasional snapshots when weather is particularly changeable (and therefore more challenging to predict) and 3) instances where certain forecasters are off on their own and deserving of recognition (good or bad). It's also true that I probably make more comments when forecasts are wrong then when they are right, but I think people are OK with that.

      Outside of snow forecasts, there's not as much to write about. And so I'll editorialize about issues of the day from a simple individual weather consumer perspective, which is different from what I bill as the primary mission of the blog. I feel there's a place for a layman/weather enthusiast to express opinions. That's what you've been seeing over the last six non-snow months.

      That said, I do think people enjoy -- for amusement purposes only -- what different forecasters predict, even if in a nonscientific, snapshot form.

      There are two weather sites that I know of that attempt more rigorous evaluation of forecasts. Forecastwatch.com assess forecasts of commercial providers. This includes analysis of far more than temps -- to include probability of precipitation, wind, amount of sun, etc. But that's a totally different ballgame than forecasts provided by your local TV mets. There's also Weatherist.com, which attempts to assess forecasts of local television forecasts. That may or may not give you more of the data you seek, but it doesn't provide the same intimate environment that this site does for discussing forecasts.

      In the final analysis -- and I'm giving away the main nugget of the future blog I referenced at the beginning -- I can determine no significant difference between forecasters over any substantial time frame. They are far more apt to be all right or all wrong since they rely on the same models. I would even go so far as to say that this pursuit -- my alleged mission -- is a rather fruitless one.

      So we're both waiting for Nate Silver to bring his skills to Minnesota weather forecasts.

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  9. Got some interesting happenings next week...........PD bringing out some of my favorite F words in his morning blog...........Frost and Flurries,in the words of Plymouth Weather Lover: Bring It!

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  10. I have always thought that the forecast highs this weekend were problematic, I really thought highs for Sat would be in the 80-84 area. I don't know why Kare missed it by that much.

    Having said that, the biggest challenge has been Sunday. With this upper level trough approaching during the afternoon I always wondered how much cloud cover we would see by say 3pm in the afternoon. I almost jumped on the band wagon of highs in the upper 80's but was very reluctant to do so. Now it looks like we could see some cloud cover.

    As it looks to me right now, Kare 11 may have the right idea in cooler bias for Sunday, (the key word here is cooler,) compared to the other forecast for Sunday.

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  11. Lets face it. This blog excels in the winter. Comparing high temp forecasts just isn't that interesting.

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    1. Agree. The only sort of exception is when certain forecasters are out on a limb from the others. But even then, whether it's 85 or 80 is a lot less significant than flurries or 4 inches of snow.

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  12. Well, it didn't get quite as warm Sunday as predicted, but it sure felt nice at 80, though it's extremely dry. I hope we get some moisture overnight. On the other hand, Wunderground's forecast for this week has improved (i.e., gotten warmer) markedly. It no longer looks like late October. I hope that holds.

    September 2012 hi/lo is running 8/3 above average thru the 16th.

    I wouldn't mind a discussion about long-term weather and even climate trends. Paul Douglas mentioned last week that less arctic sea ice causes weather patterns over North America to become stalled. Could this have anything to do with our drought?

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  13. @ Big Daddy.....Hmm.. both the Euro and the GFS are showing the possibility of some flakes falling from the sky on Fri night somewhere in MN, no measurable accumulations are expected at this time... I can't believe I just posted that, but that is what is being hinted at.

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  14. Your speaking my language Randyinchamplain,its not like its unprecented(I believe first flakes has fallen on metro as early as 9/16),but that would be cool and awesome,I will let you know if I see anything since I work the graveyard shift..........Also,fyi for everyone, Paul Huttner over at MPR had a very good write up yesterday in his blog abot the growing chances of an early fall snowfall in parts of Minnesota due to the developing El Nino and indictors he is seeing further north of here,he commented that in years where a developing El Nino was occuring that winter had an early fall snowfall,just like the 1991 Halloween Blizzard,now wouldn't that be awesome.I wasn't here that year,but I have heard stories......if something like that happened again it would be a 'treat'.

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  15. Snow showers Friday night?????.............Paul Huttner says possible on his Updraft blog.

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  16. Frost Saturday night???.........going to be a close call,of course depends on wind and cloud cover,looks to be 30-35!

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  17. FREEZE WATCH SATURDAY NIGHT.....2 WEEKS EARLY......EARLY WINTER AS WELL,WHAT DOES EVERYONE THINK?

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  18. @Anonymous,I saw that,I'm going with 32 or 33 tonight,plenty cold enough for some frost on the pumpkins,so yeah the freeze warning is definitely warranted in my opinion.
    As far as the early winter comment,I think there is some truth to what Mr. Huttner blogged about the other day when he said when a El nino is delevoping Minnesota can look for an early seaszon snowfall,question is where in Minnesota....I guess time wil tell,stay tuned.I'm just happy were starting to talk about cooler topics then summer and heat crap,and right on que since today is the first day of Fall

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  19. From nws in Duluth:

    Earliest Measureable Snowfall in 17 Years at Duluth


    0.1 inches of snow fell in the late evening hours of Friday, September 21, 2012 at Duluth. This is the earliest snowfall of the season in 17 years. On September 21, 1995, 0.1 of snow fell on that day also.

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  20. Plymouth Weather LoverSeptember 22, 2012 at 9:58 PM

    Talk of snow? Early winter? Bring the discussion on. Bring it!

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  21. Big Daddy:

    I really don't want to be a buzz kill, I love trying to forecast extreme weather events, however I think the forecast of a developing EL Nino is a bit premature, it looks like it is having a hard time getting a foot hold. There is some evidence out there that shows temps just under the surface along the Pacific equatorial region are not warming that fast, at this time I'm thinking the best we will get is a very week EL Nino, but most likely it will be neutral.

    That brings me to the chances of a early winter storm impacting the region. I think it's fairly low at this time, based on two reasons. #1) 1991 was showing was a neutral to slightly positive PDO (Pacific Decadal Oscillation,) this year so far it is trending strongly negative, so we are talking apples to oranges. #2) IMO we have to solve the drought problem that is persisting over Iowa and worsening over southern MN. Any low pressure system that develops over the Texas panhandle and tries to hook up over the favored track, just east of Lacrosse to Green Bay, may have ample moisture to work with on it's east side, but as that moisture wraps around to the west side (cold side), it's likely to run into a very dry air mass. The net result would the moisture trying to wrap into the cold sector will be spent trying to saturate the column, with not much of it reaching the ground.

    So therefore from Late September through Thanksgiving I am going with near to slightly above normal temps (if I error on temps it will be I'm not warm enough.) Precip will continue much below normal..

    Sorry dude that's the way I see it.

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  22. I noticed how remarkably similar the ECMWF and the GFS were about a powerful cold front plowing its way into the upper midwest/ lower canada about 171 hours out. The GFS pushes it further south and is slower, the ECMWF keeps it closer to the border. The GFS also has a powerful storm following behind it, but that is beyond the "plausibillity range" right now (beyond 200 hours), and the ECMWF doesn't even go that far for a comparison. I understand that the GFS is not the most accurate model (after that 92 hour retrograde "perfect storm" crazy out of this world prediction last year that never surfaced), but it is somthing to watch.

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  23. @Randyinchamplain,your not a buzz kill,I appreciate your wisdom and opinions,I said a Halloween Blizzard type storm would be a 'treat',I don't expect it in these drought conditions,but one could hope and dream,just like I hope your wrong..........this is weather and anything can happen,just like today is Sunday and the Vikings could beat the Niners...."any given Sunday",right!

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    1. As it so happens, the vikings DID beat the Forty-Niners.

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    2. @bemaki,see like I said 'any given Sunday'.......so does that mean we get a Halloween Blizzard?,here's my rally cry.......'any given October we can get a blizzard'.......for some that would be a 'trick' for others a 'treat'.

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  24. I may be crazy going this far out, but an early october snowstorm? GFS 12z seems to think so.

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  25. How about a new thread where we place bets on how long it will be until we get an additional one inch of precip? It can be cumulative.

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    1. Your wish is my command. See new thread.

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  26. It's been a long time since I've posted on this blog so I thought I would throw my two cents worth in. If the CFS v2 is correct (it has had a fairly good track record as of late), then the above average trend is going to continue right on through the winter and into next spring. It's really tough to try to predict a seasonal forecast even this far out, and those who are just looking at the fact that we will be in an El Nino winter are dumb. While El Nino is a factor, the different oscellations have to be factored in as well. Last winter was La Nina which usually means cold and snowy for us if we only look at that. The other oscellations, however, overtook the effects of La Nina and gave us a very mild and snowless winter. I really do fear as to how severe and widespread this drought will be come next spring. Unless we see a major pattern shift at some point, farmers could be in trouble next growing season.

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    1. To tell you the truth, I think this winter will be cold and dry. Dry considering the drought, and cold because of the pattern we are in. I suspect two snowstorms: One in october/november, another in February/March. Through the heart of winter, I think we will be bored out of our minds waiting for somthing to happen. But instead of waiting for it to cool down, I think we will be waiting for it to warm up enough for a snowstorm.

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