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Chinook

Mountain West- Winter

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We're forecast to get 0.1" - 0.2" tomorrow in the city. If that happens, 2016-17 becomes one of our only winters where each month had normal to above normal precipitation. It's only happened eight times since 1931-32 although it has been more common since the PDO+ era that began in 1976.

1943-44, 1978-79, 1979-80, 1982-83, 1984-85, 1992-93, 2007-08, and 2014-15 are our only winters where we've had a wet or average month every month of the winter. Worth noting that most of these were not extremely snowy cold-seasons - 1979-80, 1984-85, 2007-08 were less snowy than average, and only 1982-83, and 1992-93, and 2014-15 were very snowy (+50% or more). The core winters (D-F) were not super snowy either, although only 1979-80, 2007-08 and probably this year were duds for ABQ winter snow.

Interestingly, March was evenly split between wet/dry after those winters, but the 8-year average came to drier than the long-term average - 0.35".

Historically, a near-average to wet February that is warm in a non-El Nino year here will flip to a more mild/moist March (i.e. normal, instead of warm/wet ala Feb). Will be interesting to see if that holds up.

  Feb Mar Feb Mar
1932 57.0 57.3 0.54 0.27
1945 55.8 58.1 0.32 0.50
1950 58.0 62.5 0.38 0.04
1957 59.7 58.9 0.59 0.52
1976 58.8 59.8 0.40 0.09
1980 58.1 60.9 0.58 0.60
1981 59.7 60.4 0.67 0.80
  58.2 59.7 0.50 0.40
         
2017 59-60?   0.32+  

What do you all expect for March?

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The Euro and the GFS are both predicting snow for the Front Range on Thursday-Friday. The amounts are like 1-4". The GEFS means continue with below normal temps starting Thursday, out to 384 hours. I expect some chilly 35 degree high temps in this time frame and perhaps some more chances for snow around the 27th. The Euro has snow for us on the 27th-28th. If that doesn't work out, we will probably have snow at some point during the chilly period. As for March, I am not too good at doing analogs like you, Raindance. The CFS weeklies have cool temps on week 2-3, then a bit above normal.  That is not bad-- it's a lot better than seeing the CFS say warmer than normal for 6 weeks straight.

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Meantime, we're headed toward a top 2 warmest all-time for Feb at DEN if this keeps up and the last few days aren't too much below normal, and we've only had a trace of precip so far (though that may well change, would have to be 0.15 or less to be in the top 20).

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No doubt, we are much above average in February with just a few days to go.  The trend is -snowy- with the latest runs of the GFS and Euro, for Thursday-Saturday. Too bad the Canadian just can't see to agree. The 12z GFS has 7.5" of snow for Denver, with the 700mb closed low near Fort Collins. The 00z GFS had 0.8" of snow for Denver. Quite a difference. Yesterday's 12z GFS said 4.3" for Denver. 12z NAM has 2.8" for Denver. I must admit, the NAM winter weather forecasts this year have been a little wacky. But this time, 2.8" does not sound unusually low or high.

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Do you guys ever use Organic Forecasting?  http://www.organicforecasting.com

Rossby Wave Train & Bering Straight Rule ideas both show a fairly active first three weeks of March. I typically look at the 2m temps, 500mb heights, and surface maps - first two from the Rossby Wave Train area of the site, latter from the BSR. 

These are old meteorological ideas from before automation and models, but they seem to hold up pretty well a lot of the time, although it is sort of useless in my area in the Summer when we are perpetually under a subtropical high and the trick is getting moisture into the high. But from Oct-May I tend to look every week or so.

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3 hours ago, raindancewx said:

Do you guys ever use Organic Forecasting?  http://www.organicforecasting.com

Rossby Wave Train & Bering Straight Rule ideas both show a fairly active first three weeks of March. I typically look at the 2m temps, 500mb heights, and surface maps - first two from the Rossby Wave Train area of the site, latter from the BSR. 

These are old meteorological ideas from before automation and models, but they seem to hold up pretty well a lot of the time, although it is sort of useless in my area in the Summer when we are perpetually under a subtropical high and the trick is getting moisture into the high. But from Oct-May I tend to look every week or so.

I don't completely understand it. I thought the Bering Strait Rule applied to troughs east of the Mississippi River, but I have no idea how that connects with troughs farther west.

Trends in the models still show decent snow for Fort Collins and Cheyenne. The GFS can't decide what to do for Denver.

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There have been some 40-50 mph wind gusts at Fort Collins. Cheyenne had 38kt or 44mph steady wind

KCYS 211653Z 26038G46KT 10SM CLR 14/M06 A3004 RMK AO2 PK WND 26046/1646 SLP134 T01391056

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I've been tracking the storm for the Casper, WY area. The models haven't really agreed up until today where the GFS/NAM/CMC seemed to all point to 9-14" for the area. NWS Riverton went bullish with their Winter Storm Watch though calling for up to 18" in the area. :o

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Casper Mountain and Wyoming's mountain front could get a bunch. The NWS went with up to 24" at Casper Mountain. The cutoff of snow to no-snow will be so close for me, it is going to drive me nuts.

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Seems like the models still disagree on where exactly the deformation bands will set up. I suppose when you are dealing with mesoscale features like that in the region, you don't really find out until it happens.

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Could be inch-less here. Saw four migrating Mountain Bluebirds on my run this AM, gorgeous. They'll be in for a surprise at least regarding cold. Any bugs or old berries available so far will be frozen solid.

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Casper may get 10" out of this...not bad I suppose. The 18" WSW got me excited though. I guess the low got too far north to keep the deformation zone over the area.

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Right on time. MJO looks like it entered phase two today - pretty stormy this time of year. Looks like it may stay in 2/3 for a while, hopefully til March 5th or so. Definitely looks seasonal to cool here, first time in a while.

 

MJO Phase 2  2.23.17.gif

MJO Phase 2 fcst.gif

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27 minutes ago, AlaskaETC said:

Casper airport has 8.2" per the PIS from Riverton. Interesting that snow totals measured in the Casper area range anywhere from 4 to 16"...

That is a real sharp gradient for a relatively small metro area.  Perhaps inaccuracies?

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1 minute ago, ValpoVike said:

That is a real sharp gradient for a relatively small metro area.  Perhaps inaccuracies?

That's my guess. Measuring snow can be tricky with the winds accompanying the storm.

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20 hours ago, Chinook said:

close to rush hour in Denver

NytWOe0.png

Yeah, I ducked out of work early, but not early enough. Took me a full hour to go the 14 miles from Wheat Ridge to Broomfield. Everything had flash-frozen north of about 64th Ave. Ended up with about 3" in western Broomfield County.

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2 hours ago, PennMan said:

Yeah, I ducked out of work early, but not early enough. Took me a full hour to go the 14 miles from Wheat Ridge to Broomfield. Everything had flash-frozen north of about 64th Ave. Ended up with about 3" in western Broomfield County.

Lucky! It took me 4 hours and 6 minutes to make my 42 mile commute (door to door). My RTD bus got stuck on Alameda in the center lane, so it wasn't safe for the driver to get out and chain up. Worst commute of my working life by far.

On the other hand, I'd love to see a lot more snow before the summer hits. We're at 50% or less of average in the foothills south of I-70. Going to be a very bad fire year if things don't change soon.

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I got 3.1". My best guess of water equivalent is from CoCoRAHS, 0.34". Our streets were just not that slippery as the snow melted off of them just after it was snowing hard at 1PM.  So, with that, my best-guess precipitation for February is very near the average for Fort Collins, even though the snow will be less than average. I had measurable precipitation with freezing drizzle and snow on February 1-2, and 0.01" of rain a few days ago.

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This winter should be studied quite a bit. As far as I can tell, only winter since 1950-51 where Nino 1.2 was positive (~ 0.5C this DJF) and Nino 3.4 was negative (~ -0.5C this DJF).

By Nino 1.2, the closest years are El Ninos - 1957, 1972, 1986, 1991, 1994, 2006.

By Nino 3.4, the closest years are cold neturals/weak La Ninas - 1962, 1964, 1967, 1971, 1974, 1980, 1983, 1985, 1996, 2012, 2013.

If you use only warm AMO years, you end up with 1957, 1962, 1994, 1996, 2006, 2013

If you use only warm AMO/PDO years, you end up with 1957, 1996, 2013. 

A blend of 1994 & 1996 where 1996 has more weight actually produces a pretty decent map for temp profiles this winter.

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