Friday, December 7, 2012

Dec. 8-9 Snow Forecasts Locked and Loaded

A dusting of snow fell on ornamental grass in St. Paul on Friday.

Updated forecasts in blue font reflect forecasts as of late afternoon/early evening on Saturday. In general, there appeared to be a late afternoon trend toward somewhat higher snow totals and greater confidence in the storm.

We're about 24 hours away from the expected onset of the largest snowstorm to hit the Twin Cities in what seems like a long time. The highest snow forecast we found for the central MSP metro was for Fox/KMSP of 7 inches. The lowest was The Weather Channel with 3 inches. The most common forecast seemed to be 4-5 inches. Here are the latest forecasts that we captured late this Friday evening.

WCCO: 3-6 inches (10 p.m. news). Call it 4.5
KSTP: 3-5 inches (Jonathan Yuhas/KSTP Weather tweet). Call it 4. 3-6 as of 5pm news
KMSP: 6-8 inches (10 p.m. news). Call it 7. 4.1 with snow meter.
KARE: 4.6 inches (10 p.m. news). (4.6 for Bloomington) 3-6 (showed 4 for MSP)
Star Tribune Video (startribune.com/weather/5.39 p.m.): 6-7 inches. Call it 6.5
Star Tribune Paul Douglas (as of 11:45 p.m. blog): 2-5 inches. Call it 3.5 3-6 as of 4:40 tweet
MPR: 3-5 @MSP airport (as of 10:27 p.m. blog post). Call it 4. 3-7 as 4:10 update/5:40 tweet suggests 5-10" for metro.
NWS: "Around 6 inches" per warning statement. Call it 6. 5-9 inches as of 5:02 update
TWC: 2-4 inches per iPad forecast. Call it 3. 4-8 inches per iPad forecast at 5:40
Accuweather: 3-6 inches. Call it 4.5. 3-6 as of 5:40 p.m.
Weather Underground Best Forecast: 6 Up to 5 inches as of 5:45
Novak Weather: 6 inches (based on graphic). Call it 6. Solid 6 per afternoon graphic.
DDwx-MN met from Atlanta: 4
ShakopeeWeather: 4-6 inches. Call it 5

Note that we've made the call that the amount for the airport will be in the middle of the snow range forecast, a reasonable deduction given that the airport essentially represents the central core of the metro.

Roll the dice and let the games begin. Follow us on Twitter and like us on Facebook to get more timely updates.

52 comments:

  1. Count me in for 2-4" at MSP/south metro and 4-7" in north metro after looking at the 00Z models.

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    1. So that would be 4 for the official measuring stick at MSP airport, Tony? It may be arbitrary, but I like to assess the forecasters based on performance for a particular location.

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  2. Interestingly enough, KSTP issued a late tweet that upped snow totals to 5-8 for the metro. Snow forecasts are indeed a moving target.

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  3. Yeah I'll take 4 tops at KMSP, even hesitant on that. NAM trended from 7" down to 4", GFS went from 3.5 to 2.5" from 18z to 00z. Not seeing anything over 4 at the airport unless some amazing thundersnow happens to show up. Just don't get higher amounts than that at this point, seems like a weird move upward by KSTP.

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  4. NWS still going with Winter Storm Warning for the metro core...question for you Bill or others who meant know,looking at the point forecast for Golden Valley on the NWS website calls for Saturday night 3-5" of new snow,then Sunday calls for 2-4" of new snow,so then the storm total prediction/forecast is 5-9" right?thats what I should expect according to the NWS right?seems much higher then everyone else or the big range is for fluctation of the track of the storm I'm guessing,but when you here any range I personally would expect the first number to verify and the second higher number is just in case the storm does something that was unexpected.

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    1. @Big Daddy I find the NWS's two-part snowfall projections confusing as well, and likewise, I would assume you can add the two snow "installments."

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  5. Yesterday was a great example of what bothers me about a number of forecasters. It seems that 'forecasting' has become just reading model output and changing your forecast based on each model run. I'm not saying that forecasts should not be updated, but they should be done with more than a model run or two in mind. Yesterday's models were largely outliers of what has been shown all week. Even when they were outputting heavy snow over the metro, it didn't exactly align with the storm track, and where the heaviest snow should be. The northern surface low has always looked to track near or just north of the Twin Cities, meaning the heaviest snows will be to the north. This storm also was not located in the US until late yesterday afternoon. This means that the models did not initialize using radiosonde data to get a good picture of how this storm was developing in the US until the 00z runs last night.

    All that being said I think too many forecasters bit on the forecast models from early yesterday which were largely outliers. Now many in the metro are amped up for a large storm, but will end up being disappointed with only a few inches. I think the winter storm warning is too far south and most of the metro will fall in the 2-4" range, which is not much different from what the thinking was two days ago.

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    1. @Randy Great point. The general weather "consumer" part of me wishes you'd never hear anything about models. And when television forecasters slap the detailed, here's-what-this-model-shows-is-going-to-fall output, I think they suggest an exactness that's ridiculous. And then you get the ones who say, "here's what the model says but I don't believe it." So why show it?

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    2. I totally agree with Randy as well.
      Storm is being way overplayed for the metro. I personally think 4 inches is really stretching for msp area.
      About the Winter Storm Warning I also believe it is totally unwarranted for the cities, however my thinking is that because they are issued by county, and Hennepin county stretches a good deal to the N and W, some areas may reach warning criteria, but that means you automatically include the whole county. I am surprised that Ramsey county, which is smaller is in the warning area.
      My prediction for the official measurement at msp: 1.9 inches.

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  6. Randy, couldn't agree more, the heavy snows that the GFS and Nam were showing earlier didn't make much sense to me, even after the 08/0z runs I chucked the Nam. Last night in the previous thread I said 3-4 for MSP, so 3.5 would be good, don't see any reason to change it this point. If any thing that may be to high as the Euro is showing the southern edge of the 3" line right along 45°N, or roughly from Golden Valley to Roseville area, based on a ratio of 10 to 1. I think the ratio will be around 11 or 12 to 1.

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  7. Current model average is about 2.8 for MSP.

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  8. 12z GFS is more aggressive with the precip, but with the low passing mostly over the metro, I wonder if that isn't the result of feedback issues.

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  9. Unrelated question here....if I wanted to get a quick check on a visible satellite loop to see the progress of clearing for MSP, what's the best, most simplest link to follow?

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    1. http://www.intellicast.com/National/Satellite/Visible.aspx?region=cbg

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  10. I would agree with most of the assessments above if the low pressure were a true surface cyclone. However, I consider the low more of a mid-level circulation rather than a strong surface low. With that being said, the heaviest snows tend to fall near or just north of the mid-level low track along the axis of pivot area or trowal. Meanwhile, the true surface low reorganizes over IL on Sunday. I believe this is why we will not have to worry about liquid mixing in with the snow during this event since the lower and mid-level warm air will be displaced well south of MN near the true surface low. I think that the UKMET is onto something when it showed a solid area of accumulating snow across all of MN from north to south and it showed energy/dynamics shifting southeast with time on Sunday.

    With all that being said, I still expect the heaviest band of snow (6"-9"+) to stretch from ABR east to STC/BRD and continuing east into the Hayward WI area. This would include the northern MSP metro. I wouldn't be surprised to hear of some northern metro cities measuring 7" to 8" of snow. I'm thinking a good 5"-6" at MSP. This is a fantastic scenario for the whole state since most of us including RST, AXN, DLH, BJI, etc. will receive a blanket of white by Sunday PM. Of course, all bets are off if a dry tongue and/or warm layer rolls in and screws things up. I don't expect warm air to be an issue, but I am a bit concerned about dry air getting entrained into this storm.

    It should be fun to watch this thing evolve. It is about time we get something to talk about.

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    1. @Novak- good point. Most of our snows come from surface lows, so the assumption is that the snow will travel around like a surface low. Being a mid-level low mixes things up a bit. It would make sense if the big snows fall closer to the low because in reality it is the same distance from the center, but since it is higher up in the atmosphere, the low will sort of "draw" the snows closer to it. However, I know little of the nature of mid-level lows. I will be interested in how this system plays out.

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  11. Currentlyu, a band of heavy snow extends from Mobridge to Heron,SD, and then eztends soutward to Chamberlain, and Lake Andres, SD. The counties affected by this band of snow are Walworth, Potter, Edmunds, Faulk, Hyde, Hand, Spink, Beadle, Buffalo, Jerauld, Brule, Auroa, Douglas, and Charles Mix counties. The line is expected to continue to propogate northward and expand west and east. The band will reach Abredeen by 2:00pm, Watertown by 3:00, and the MN/SD by 5:00. This propogation could accerate or decelerate if certain conditions are met, say, if the line starts spreading more rapidly or there is more dry air than anticipated. Will watch.

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  12. NWS point forecasts now say heavy snow and much higher totals, here in Red Wing it went from 1-3 on Sunday to 3-5, with 1-3 tonight, making 4-8. Models must be bringing it back south

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    1. This is why: (RAP model)

      http://mag.ncep.noaa.gov/NCOMAGWEB/appcontroller?page=Image&prevPage=Param&image=..%2FGemPakTier%2FMagGemPakImages%2Fruc%2F20121208%2F20%2Fruc_namer_002_precip_p01.gif&fcast=002&model=RUC&area=NAMER&storm=&areaDesc=North+America+-+US+Canada+and+northern+Mexico&cat=MODEL+GUIDANCE&rname=PRECIP+PARMS&pname=precip_p01&cycle=12%2F08%2F2012+20UTC&imageSize=M&currKey=model&scrollx=0&scrolly=0&prevArea=NAMER&prevImage=yes

      click next to progress screen

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    2. Also statement issued by NWS:

      ...MAJOR WINTER STORM BEARING DOWN ON THE UPPER MIDWEST TONIGHT
      THROUGH SUNDAY EVENING...
      ...BLIZZARD CONDITIONS EXPECTED ACROSS WESTERN MINNESOTA SUNDAY
      AFTERNOON AND EVENING...

      .A POWERFUL WINTER STORM CONTINUES TO ORGANIZE ACROSS THE DAKOTAS
      AND WILL BEGIN AFFECTING WESTERN MINNESOTA THIS EVENING...AND
      EASTERN MINNESOTA AND WESTERN WISCONSIN AFTER MIDNIGHT. LOW
      PRESSURE WILL TRACK FROM ABOUT NEW ULM TO ROCHESTER ON SUNDAY
      WHICH IS A LITTLE FURTHER SOUTH THAN EARLIER ANTICIPATED. MODERATE
      TO HEAVY SNOW CAN BE EXPECTED AHEAD AND NORTH OF THIS LOW TRACK
      TONIGHT AND SUNDAY.

      BECAUSE COMPUTER MODELS HAVE SHIFTED SOUTH WITH THE TRACK OF THE
      LOW...WINTER STORM WARNINGS AND WINTER WEATHER ADVISORIES HAVE
      ALSO SHIFTED SOUTH. WINTER STORM WARNINGS ARE NOW IN EFFECT NORTH
      OF A LINE FROM REDWOOD FALLS...TO RED WING MINNESOTA...AND EAU
      CLAIRE WISCONSIN TONIGHT THROUGH SUNDAY EVENING. TOTAL
      ACCUMULATIONS WILL RANGE FROM 5 TO 9 INCHES...WITH THE HEAVIEST
      TOTALS NORTHEAST OF INTERSTATE 94.

      WINTER WEATHER ADVISORIES HAVE BEEN ISSUED SOUTH OF THE WINTER
      STORM WARNING DOWN TO THE IOWA BORDER TONIGHT THROUGH SUNDAY
      EVENING. TOTAL ACCUMULATIONS HERE WILL RANGE FROM 3 TO 5 INCHES.

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  13. NWS twin cities has issued a blizzard warning for as far east as Sibley and Nicolett counties.

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  14. I just read the latest from the NWS. The storm has slowed its forward progress and has shifted southward. That puts the entire metro into the moderate to heavy snow zone of 5-6 inches plus. The winds will kick in tomorrow to cause blowing and drifting in the outlying areas along with plummeting temperatures. It sounds like a good ole fashion Minnesota snowstorm! Enjoy the snow, but be smart and be safe if you have to venture out from the warm confines of your couch tomorrow. A better idea might be to hunker down inside and root on the Purple.

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  15. The snow band in sout dakota has continued to propagate and expand eastward, and has grown in size dramatically. The storm has left relativley few counties, and now encompasses several more.

    The following counties In South Dakota are now being or contine to be impacted:

    Mcperson, Edmunds, Faulk, Brown, Marshall, Day, Roberts, Grant,
    Spink, Clark, Codington, Hamlin, Deulel, Brookings, Kingsbury, Beadle, Hand, Buffalo, Jerauld, Sandborn, Douglas, Davidson, Hanson, Miner, Mccook, Lake, Moody, and Hutchinson.

    These counties in eastern North Dakota are now being impacted:

    Logan, Lamoure, Mcintosh, Dickey

    These counties in Minnesota are now being impacted:

    Rock, Pipestone, Lincon, Lyon, Murray, Nobles, Yellow Medicine, Lac Qui Parle

    Continued northward and eastward expansion of this band of moderate to heavy snow is expected. Snow is expected reach Wilmar by 6:45, Alexandria by 7:00, and St. cloud by 9:00. Giving a pliminary shot, Expect snowfall here between 11:00 pm and 1:00 AM sunday.

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  16. GFS now sending heaviest snows over north metro. Hope it verifies.

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  17. This proves to all of you who earlier were soooo sure of yourselfs about lower snowfalls and were doubting Thomas of the NWS about their warning area,give it a chance the NWS I'm sure knows a lot more then all of you COMBINED!....the only exception is Novak who didn't waver,good job Novak,except you all maybe short with the inch totals 8-10 becoming more and more likely.

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    1. So you are declaring who's right before a flake of snow even falls in the Twin Cities? I still have not seen a good reason to change my forecast from earlier today, regardless of the 18z runs. I put very little stock in the 6z or 18z model runs, and the RAP has been terrible since it replaced the RUC earlier this year. I hope I'm wrong because I'd love to see the Twin Cities get dumped on, but you have to wait and see how this thing plays out overnight.

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    2. Who are you,"to put very little stock" in model runs,these so called models are all we have to help predict the weather,you just can't throw it in the trash,their there for a reason,if we didn't need them then why have them!

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    3. Not neccesarily. Most forecasters have their own formulas that they use. All a model really is a certain formula, and the ensemble are slight varitions of that formula. The problem with weather forecasting is that these formulas are not perfect, which is proved time and time again. In order to predict further out, we need increasingly complex formulas which encompass more and more of the earth's patterns and these formulas are less accurate.

      And Randy- Don't disc weather models. They are pretty amazing in what they do. Sixty years ago we had trouble even going two to three days out. Now we can predict, although quite roughly, up to ten days out with some accuracy.

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    4. I didn't mean that I completely discount the models, you are right they are all we have. But the runs at 00z and 12z are the best because of the updated weather balloon data that goes into them. 6z and 18z are typically not as accurate. That being said the 00z NAM and HRRR models are out and have shifted the heaviest snows to the south. The heaviest band looks to be from Willmar to St. Cloud, with more in the metro. Still do not be surprised if warmer and drier air reduce accumulations in the Twin Cities. Temps right around 32 do not make for an efficient snow maker.

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  18. GFS now spitting out .75-1.00 for metro. If parts are 1-11 or 1-12, that mean 8-12 inches of snow.

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    1. Ignore this comment. I clicked on the wrong link.

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    2. Novak just tweeted that the latest NAM is showing 14 inches at MSP.

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    3. Okay, GFS now has a foot.

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  19. Numbers keep going up and up,I love it!

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  20. Even Paul Douglas is upping his amounts, now giving a range of 5-10 inches and says it will now snow into the evening Sunday night. Perhaps I'm not going to Wild Mountain after all...

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  21. Plymouth Weather LoverDecember 8, 2012 at 9:56 PM

    I am peeing my pants. BRING IT!!!!

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  22. I am really getting fired up for this one! This is absolutley mad. Let me quote just two days ago, from Randy:


    "Friday's storm will pretty much be a non-factor for most of Minnesota. Sunday's storm is stronger but overall is split into two different systems. Earlier in the week the storm to the south looked like it would be stronger and become the main driver for snow. But that storm now looks weaker and will be mostly a rain producer. The storm to the north will move across the ND/SD border and into Minnesota. The heaviest snows look to be north of the Twin Cities, with only a slushy inch or two possible in the metro as warmer air works northward ahead of it. You can click on my name to go to my blog where my forecast snowfall maps are located."

    Now, From AB:


    Novak just tweeted that the latest NAM is showing 14 inches at MSP.



    I am sure novak is going to show up here sometime very soon...

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  23. @PWL

    I tell ya, I almost did, too.

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  24. Kare 11 is on board with higher amounts, but not as bullish as some. Saying 6 at MSP, 6-10 north metro/St. Cloud

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    1. I missed KARE11 but I'll take the 6 you mentioned for the new recap.

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  25. I am guessing KARE is being quite conservative at the time. I am sure teh yare surprised at what the models are showing right now. I think they will wait for further verification before they go all out.

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    1. Excuse spelling errors. teh yare should be they are.

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  26. And what do you know: The weather channel is not naming this storm, even though there are blizzard warnings associated with it. And they do not give a detailed reason why.

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    1. Althoguh I do have a good idea.

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  27. Was there any question that these "named" storms would be isolated to the east coast?

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    1. I would give a fifty-fifty chance that they would name a blizzard here if it threatend to knock down a skyscraper in the Twin Cities. I am sure that they will name a snowstorm if there is one inch predicted at New York. This is why I dislike the weather channel so much. If you watch them, they usually do not say anything correctly.

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  28. Ok the totals are rapidly going up, the last RUC backup model I saw showed a 10-12" bullseye over the entire metro, that is a 24 hr model, it had 6-8" over the metro by 2pm and 10-12 by 8pm. The rap which is a 18hr model had 6-8" by 1pm in western Henn. county with it still snowing heavily.

    I have never seen the Euro take a swing and miss this bad, this close to a winter storm over the last three years, this has been a real challenge for all forecasters.

    I believe it was in one of Fridays AFD's from MPX where they talked about a experimental model which has showed some skill, showing a track further South, which would put the metro more in play. Does anyone know which model they were talking about? It had to be a least a 48hr model. Maybe someone that is on facebook could ask them which one, I'd love to know.

    I don't know if you call this now casting or not but I'm going with 10" at MSP.

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  29. I think that might be the Rapid Refresh (RAP) model.

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    1. Don't think it can be that, the Rap is a operational model, not experimental model and it only goes out to 18 hrs.

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  30. New post for final, final pre-storm predictions! http://www.minnesotaforecaster.com/2012/12/its-post-time-ehrrr-snow-time-final.html

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  31. Alright, for anybody up already, what's this big pouch of dry air punching in from the south going to do to decrease the snowfall totals? Just shy of an inch of snow here in Northfield this morning.

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