Beware the computers

Computer models are frequently cited as source points for our weather forecasts.  That has been the case since the first “super-computers” were introduced to the world of weather prediction several decades ago.

The computer “guidance” is a mathematically-derived prediction of the state of our weather, and there are a dozen or more different models available.  The United States has several (GFS is one of them), but there are also Europeon, Korean, Canadian, etc. computer models.  Sifting through all of this varying information can be mind-bending.

Here’s the bottom line, and the point of this blog post:  not a single one of these computerized forecasts are truly reliable on a consistent basis.  We, in the meteorological community, often put too much faith in the forecast information spewed forth from our trusty computers, but in the end we must depend on our own “gut” feelings when we make the final call.  That much hasn’t changed over the years.

Yes, the quality of this information has improved tremendously over the nearly 30-years I’ve been in the business, but we still have a very long way to go.  



21 Responses to Beware the computers

  1. Jeff says:

    I agree with David. It does get frustrating and it’s looking like an entire generation in Richmond will grow up never seeing a snowman or knowing what a snow day at school is. Hopefully, that’s not the case.

  2. harrison says:

    a 90 percent chance of snow? that will never happen

  3. Chris says:

    cool i guess since busting on so many snow scares in the past, all the stations are playing it safe by not mentioning unless there is more than a 90 percent chance of it happening.

  4. Jeff J says:

    The best bet is to always call for rain no matter what and you’ll only be wrong once in a decade or so.

  5. David Tuck says:

    Of course now these wacky models are backing off the idea of the big snowstorm this weekend. It’s funny how the European is always right this year EXCEPT when it shows a snowstorm for us. Very frustrating!! Chris, the stations are calling for mid 40’s because there’s no storm coming now, but if the storm were still in the mix, the counter clockwise winds would pull colder air from the north down into the system, so just because it’s not cold enough to snow doesn’t mean that it can’t. The storm would import the colder air.

  6. Chris says:

    if thats the case why are all the stations calling for highs in the mid 40’s this weekend?

  7. David Tuck says:

    I have never heard of a Miller C storm. A Miller B usually does us no good. It usually starts as a clipper that redevelops off the east coast, but usually it’s too far north to help us. Our big storms are almost always Miller A’s or we can sometimes get 1-3″ from a clipper, but usually the mountains eat ’em up. BTW, the 0z GFS trends towards the Euro and Canadian snowstorm, but still heads a bit offshore which is fine because that’s its bias. All of this information is available at

  8. Jim VB says:

    David, I think I have seen the terms used before. I get the impression that a Miller B storm is similar to an Alberta clipper. I have also heard a Miller C storm described, but I can’t find anywhere which says what that is. What is a Miller C Storm?

  9. T says:

    Who’s knows when the next time the area will have a big snow but I think we are way over due. Its just a matter of time.

  10. Karen says:

    Mr Tuck please tell us that all is coming together nicely and we need to get the sled out from the very, way back of the garage and scrap off the rust, knock off the dust and get ready for some snow LOL

  11. David Tuck says:

    Jim B, The Miller A is the classic gulf of mexico snowstorm. Energy dives down from the NW, gathers strength in the gulf with lots of moisture and with high pressure to the north and hopefully some type of blocking in SE canada, it provides the nor’easter type of storm we haven’t seen since Jan. 25, 2000. Of course, it might disappear off the models later tonight, but I doubt it.

  12. Jeff J says:

    A big storm this weekend would require a lot of things to come together so I’m not getting excited about it but to see the variables as possibilities is nice. It makes me think snow can still happen here.

  13. Jim B says:

    David, you made mention of a “Miller A” storm. Can you explain to us what that is, as well as what a Miller B and especially a Miller C storm is? Thanks.

  14. james says:

    Because of all the ‘nearby’ geographical factors, I suppose it’s hard for the various computer models to ‘correctly’ predict (or at least agree on) winter weather for Richmond. I wonder if those same models have better ‘success’ in forecasting weather for other parts of the country no so affected as we are??

  15. Johnson says:

    6:30 pm Update:

    Put today’s 18Z DGEX (one of Mad Man Henry’s (Premium)(Pro) favorites) model run firmly in the camp with the Canadian and European models. Southeast Virginia folks, it should be your favorite model as well; it shows a good 12-18 inches there.

    This quote is from a blog by Meteorologist Frank Strait at…..All of this talk about Spring and warm weather could quickly be haulted if everything comes together with this storm. That being said…there is A LOT that needs to come together.

  16. Ray says:

    I’m with you David. Hopefully the GFS will jump on board with this solution and get our hopes up one more time!

  17. David Tuck says:

    Two of these computer models, European and Canadian are showing a Miller A east coast snowstorm Sun/Mon. Euro is unbeatable at this time frame this year, so I’m cautiously very excited right now.

  18. DAC71 says:

    I’m personally looking forward to the mild and warm temperatures of a Richmond Spring. Thanks for staying on top of things Jim!

  19. Mike says:

    No worries, Jim. I don’t care how complex the computers get, nature will always be one (or more) steps ahead of them. Snow would have been nice but hey, time to move on and think Spring. As for me, I am ready to put the boat in the water. One thing about the weather we know for sure around here: SUMMERS ARE HOT AND THAT YOU CAN COUNT ON!!!!!!!

  20. Jim VB says:

    The computers merely tell us what COULD happen. As the actual day approaches, I expect many revisions in these models, and so they suggest but don’t necessarily predict.

  21. Jenn says:

    True Jim, only God himself can give 100% accuracy…:)

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