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Chinook

Mountain West Discussion

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Everybody, this is the new thread for winter. It is slowly getting cooler outside. Not too much is happening with the weather right now. It will get cooler and windy in northern Colorado tomorrow, but it's not much to talk about. In the long range, the GEFS ensemble means are showing a trough in the northern Plains by Oct. 26. Ensemble means have changed somewhat in the last several days, though.

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Current conditions at

Denver - Centennial Airport (KAPA)

Lat: 39.56°NLon: 104.85°WElev: 5869ft.
bkn.png

Mostly Cloudy

76°F

24°C

I guess if it can snow 4-6" and be 23 F the following day in the summer thread, we can have these conditions in the winter thread.

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The latest GFS and Euro are showing some snow for WY/CO in 6-7 days. As I said before, models have been changing somewhat in the last few days, probably due to large changes in handling the Pacific pattern. So, it's possible that they trend away from showing snow in that time frame.

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Once the MJO settles down a bit the models probably will be a bit more consistent. It is interesting looking back on the BOM site and seeing the years with similar big amplitude MJO progressions in the Fall.

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GFS/Euro continue the forecast of the quick cold shot and snow for the Front Range next Friday, maybe even some measurable snow for northeast New Mexico. Maybe some high temps in the 30's.

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Here is an interesting question for RaindanceWX (please don't overwhelm me with data in your reply.) This upcoming winter may be a (very?) weak La Nina with a -QBO... for the first time in 3 years... go figure. (The QBO should repeat once every 2 years.) Then some of the years that stand out as analogs: 2007-08 (a real La Nina with -QBO) and 1996-1997 (a near neutral La Nina with -QBO). Both were a hard cold winter in the northern US.

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In the medium range, Typhoon Lan in the Pacific will help strengthen a storm in the Bering Sea... it's not the exact same storm though. Then the GEFS means have cool temps in the central Plains to Midwest for a while. There is an interesting similarity to 2014. In Late Oct 2014, Typhoon Nuri transitioned to becoming the strongest storm in the Bering Sea in history. Then this series of events dislodged a cold air mass from Canada into the US, and it was very cold here in Colorado for a few days. Hopefully we won't see sustained temps below 10 deg in November like in 2014.

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Yeah, that one killed our cherry tree and a chunk of our apple tree. I flew to Kansas City that morning, and the 50 kt wind gusts as the front went through were shaking the plane so much as it was loading at the terminal that they had to pause people getting on for a few minutes. <10 F is fine, but gradually!!

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4 hours ago, Chinook said:

Here is an interesting question for RaindanceWX (please don't overwhelm me with data in your reply.) This upcoming winter may be a (very?) weak La Nina with a -QBO... for the first time in 3 years... go figure. (The QBO should repeat once every 2 years.) Then some of the years that stand out as analogs: 2007-08 (a real La Nina with -QBO) and 1996-1997 (a near neutral La Nina with -QBO). Both were a hard cold winter in the northern US.

I like 1996 & 2007. I don't use the QBO though - but I arrived at those years because the QBO seems to be linked to the solar cycle, and 1996/2007/2017 are at similar places in the solar cycle since it is nominally an 11 year cycle but the current cycle was super weak. 1985, which I also considered, would have been similar too. This month is down to around 10 sunspots, July 1996 to June 1997 had 14 or something? That's how I blend in the sun. I may be mis-remembering this but I've seen a paper with QBO re-constructions from data in Indonesia back to 1900 that implies the weirdness w/ the QBO last year not behaving as expected may have happened in the 1940s too after the triple El Nino of 1939-1942, so 1943-44, 1944-45 (which I have in the analogs) are similar. 

The QBO is a 28 month cycle right? That means in most solar cycles, it cycles through ~five times. That is one of the ways solar data is useful in my opinion.

I don't think this is a cold winter in the Southwest, at least where I am, because forgetting my analog methods, models, etc, the history in the region says hot Junes (which we had) are almost never (15/16) followed by a winter 2F or more below normal - that's true in La Nina, Neutral, El Nino, +AO, -AO, +NAO, -NAO, low solar, high solar etc. So I respect that figure a lot. But enough went right in the Summer and enough has changed in the background state of everything to make me think this is one of our "colder" La Ninas. Still around average though. The average should be fun though...suspect its a lot of slightly warm days and then 20-30 days of incredible cold.

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I use the Modoki / PDO / AMO values that match what the oceans are forecast to look like, in similar ONI/Solar years, that had similar weather conditions in my area over a long time. That eliminates a huge number of years. I also tend to throw out years on the opposite ends of the spectrum on a given important factor, say the AMO. It takes a super long time to evaluate the accuracy of this stuff on my end because I have to manually look at the misses by state/region and look up the state sizes to come up with a national accuracy figure, but when the seven things I use are guessed/blended together correctly it does seem to work at 55-85% nationally on a seasonal basis for winter. I'm not Nostradamus, so I'm sure I'll be off on one of the figures - the PDO is actually the hardest to predict in my experience since everything resets in October,

My system uses a three tiered weighting:

AMO, ONI, Solar: x3 each

Modoki, ONIp: x2 each

PDO, Monsoon; x1 each

Matches are then automatically highlighted if they are close enough to get a score of 8 or more out of 15 possible points. Some years are never fully reproducible, I couldn't get 2014-15 with my system because it had the highest PDO value since 1900 for Nov-Apr, and I basically didn't know what to do. The system is basically designed to rank the years from best to worst match, and then it is much easier to analog everything. It takes out 80% of the time/effort.

My analogs are in the winter outlook I put out - https://t.co/ZnvyQletct 

1932 (x2), 1943 (x3), 1944 (x3), 1996 (x3), 2005 (x3), 2007 (x3), 2008 (x2), 2012 (x1)

ANyTDfN.png

imageproxy.jpg

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5 hours ago, Dakota said:

Nice batch of anomalously cold air to close out October in the mid-section of the country on the CPC 6 - 10 day progs...those guys do a pretty good job and at this range its pretty much a certainty that some of it will work its way down.  Most of the unsettled weather should be east of the Dakotas; the UP of Michigan, Arrowhead of Minnesota, northern Wisconsin have a good chance for some early season snows....as the Superior lake effect machine kicks in for the first time.

610temp_new.gif

I was worried for a while that we'd torch here in Oct, when I had it near average here, but it looks pretty good now. I just checked my analogs for winter and the ocean analogs for winter are actually nearly identical to current conditions. Probably one of the best matches I've ever produced for the Northern Hemisphere actually - 

6JB4pPE.png

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This was the hottest World Series game-time temperature. This is some remarkable weather. I wouldn't want to be there. I'll take my (relatively normal) low of 31 and high of 65, thanks very much.

NrZRKOt.png

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Looks like some exceptionally dry air is coming through in a couple days. Been a couple years since we've had that. It's a good way to keep the highs from getting out of control though in the absence of a super high, since the lows will crater each night. Climatology for ABQ (airport) is first freeze on Oct 31 - would be nice to have it a few days early. Highs in the mid-50s here are always welcome too.

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This was posted by NWS-Ocean Prediction Center. (October 24, 12z) This storm at the edge of the Aleutian Islands was enhanced somewhat by the typhoon. It always amazes me that this stuff affects us from thousands of miles away.

kxNhCix.jpg

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This Rapid City observation would count as a severe thunderstorm report if it happened with a convective storm

KRAP 261352Z 33041G52KT 10SM OVC030 03/M03 A3006 RMK AO2 PK WND 33057/1259 SLP186 T00331033

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Raindance, how do you generate the snowfall % of 1981-2010 normal plots? I thought maybe that was the Midwest Regional Climate Center, but I haven't even used that web site enough to know.

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1 hour ago, Chinook said:

Raindance, how do you generate the snowfall % of 1981-2010 normal plots? I thought maybe that was the Midwest Regional Climate Center, but I haven't even used that web site enough to know.

It is that site. You can do snowfall anomalies for a custom period via interpolation. It takes 10-20 minutes to generate each map, so I try not to use it to often, but the data goes back a very long time, so you can use older analogs.

I like to up local forecaster predictions on Youtube - one the main meteorologists in Portland, OR is predicting a near-normal to below normal winter for precip, which is kind of what I think what will happen.

 

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2 hours ago, Chinook said:

Raindance, how do you generate the snowfall % of 1981-2010 normal plots? I thought maybe that was the Midwest Regional Climate Center, but I haven't even used that web site enough to know.

V15fbGT.png

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Thanks to Raindance I was able to figure out the MRCC web site for making these plots. 2010-2011 was the most disappointing snow year since I moved to Colorado. It was also the last strong La Nina (which is not necessarily saying that it will be like this year. ) The mountains west of me got about 400" of snow by my estimation off this plot, and my area got 22" ... just a difference of 380". Actually this 200% of normal for Steamboat Springs and the Park Range is nothing short of incredible.

YKDhFzj.png

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1 hour ago, Chinook said:

Thanks to Raindance I was able to figure out the MRCC web site for making these plots. 2010-2011 was the most disappointing snow year since I moved to Colorado. It was also the last strong La Nina (which is not necessarily saying that it will be like this year. ) The mountains west of me got about 400" of snow by my estimation off this plot, and my area got 22" ... just a difference of 380". Actually this 200% of normal for Steamboat Springs and the Park Range is nothing short of incredible.

YKDhFzj.png

I was wondering what you were trying to do.

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