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Mountain West Discussion


Chinook

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Coming up soon, we should have light snow tomorrow in Colorado. Then, for Saturday/Sunday, the GFS/Euro/Canadian all have a version of an upper level trough and snow for the Front Range. The 00z GFS and 06z GFS had some more snow for Denver (4.4'"). The 12z GFS had a rather weird upper trough scenario. This isn't totally fantasy snow!! The Euro has a look that is like this. It might be kind of a complicated scenario at 500mb, though, so that's usually bad.

gd5P406.png

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The GFS has been rather consistent about New Mexico finally getting a widespread snow event within a non-bs time frame. Kind of excited. Back in 2010-2012 when it was dry for an extended period we ended up with water restrictions, wasn't fun. We're not there yet, as we had three pretty wet years in a row from July 2013 to June 2016, and the most recent year was not terrible.

The JAMSTEC continues to insist that storms basically miss the West Coast the entire winter, but get to the interior West at an average rate, with the Midwest wet, which to me implies the incredibly far south suppressed polar jet is here to stay, as is the ridge blocking the West. Some storms would come into the US through Baja too I suppose, given that the SW is not shown dry, except on the coast. You can kind of see where it thinks the rogue subtropical jet lows will come up by Baja.

8x65xg6.png

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On 12/3/2017 at 4:04 PM, raindancewx said:

I'm using NM records as a proxy for when I expect a pattern change. Albuquerque is near 60 days without measurable precipitation. Record since 1931 is 106 days, record since 1891 (different sites) is 109. That means something has to snap by January if we aren't going to break the record (which is unlikely given annual precipitation is up 10-20% here since 1931).

My analogs were pretty warm Nov 16-Dec 15, but for Dec 16-Jan 15, many years that had been very warm for long stretches flipped very cold. Most recent example would be 2012-13. My best matches for precip/highs by month imply the flip to cold is more likely to not, and since this huge dry stretch has to end at some point, I think Dec 16-Jan 15 is the period to watch. 

For Mid-Oct to Mid-Nov and Mid-Nov to Mid-Nov to Mid-Dec you had a stronger warmer signal than cold signal, but it flips after that. The Nov 16-Dec 15 period is pretty similar to 2012 right now, and not super far off from 1932, 2008 and a few others. Should correct down hard in the next few days to be similar to the rest of the years.

Year Oct 16-Nov 15 N16-D15 D16-J15 J16-F15 F16-M15 M16-A15 A16-M15   N16-F15 F16-M15
1932 62.3 53.8 41.8 43.0 58.9 64.8 66.6   46.2 63.4
1943 64.6 50.4 36.9 48.9 55.6 61.2 70.6   45.4 62.5
1944 64.5 46.8 49.5 50.2 56.4 60.2 75.1   48.8 63.9
1996 59.4 53.0 44.0 49.4 58.5 64.2 73.5   48.8 65.4
2005 66.9 50.0 54.3 52.1 58.6 66.6 78.0   52.1 67.7
2007 69.2 51.8 43.7 47.2 57.8 67.1 73.7   47.6 66.2
2008 65.7 54.1 48.1 55.5 61.8 65.1 79.3   52.6 68.7
2012 67.7 57.5 40.6 52.1 57.7 68.2 74.1   50.1 66.7
                     
2017 68.4                

 

Nov 16-Dec 15 now looks like an almost exact match to 2012 here once again - the mean high for the period should be 57.2 or 57.3F. Given that the GFS is showing two huge snow storms for NM in the next ten days, the flip to sudden, seemingly random cold, may end up verifying. 

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I guess my area over-achieved with this 1" of snow. The GFS had 0.3" and the NAM and 3km NAM had none. The snowstorm at hour 72 (Sunday) has been weakening on the GFS, Euro, and NAM. This looks to be mainly a 3-6" snowfall for Wyoming with some lighter snows in other western areas.

Mid-month update on the western snowpack: the Southwestern US has done very badly. Also, most northern basins are below normal now.
 

8XJ5RCe.png

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Never have been a fan of red or orange... blue on the other hand

 

41 minutes ago, Chinook said:

I guess my area over-achieved with this 1" of snow. The GFS had 0.3" and the NAM and 3km NAM had none. The snowstorm at hour 72 (Sunday) has been weakening on the GFS, Euro, and NAM. This looks to be mainly a 3-6" snowfall for Wyoming with some lighter snows in other western areas.

Mid-month update on the western snowpack: the Southwestern US has done very badly. Also, most northern basins are below normal now.
 

8XJ5RCe.png

 

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4 hours ago, Mercurial said:

Certain other subforums would have multiple tracking threads with thousands of posts to track 1" of snow.  Not us, nuh uh.  We're the Rockies, we're a snow region :)

Between the front end thump, the coastal front making its way 1700 miles west, lack of a change to rain, the always-discussed bombogenesis, and the ever-present but elusive backlash, I got a whopping 1.3". Call me a weenie now, wouldja. 

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GOES-16 has now been transferred to its East orbit (75 deg west or 70 deg west.) I was hoping the new cool satellite would be over the Pacific so we could get better weather forecasts for the West. But no, we still have (just) GOES-W covering a lot of the Pacific Ocean. The ground looks pretty non-snow covered on the plains.

HvzYdfH.jpg

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Today's models are showing two storms for the Front Range. One is a storm on Thursday, with a decent setup for CO, WY, and possibly the northern Plains. The GFS has 5" for our metro areas (0.3" of water equivalent). The Euro also has 0.1" to 0.3" of water equivalent. So, basically the Euro and Canadian are not too different than the GFS. It is now appearing reasonably likely the 2nd storm is on Saturday/Sunday, accompanied by a cold shot that gets the metro areas to the single digits.

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23 hours ago, Chinook said:

Goodness! By the way, the 12z Euro has 0.4" of QPF (4"-8" of snow) in the next 7-8 days, so the GFS is definitely too high.

Yeah- NWS is saying maybe a couple inches on the plains total the next 5 days. Hope it's more than that- cold without snow is not very fun. If the -20s were to pan out it would be the coldest since we arrived in 2010.

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I don't know when it will happen exactly, but historically, after a super-dry Oct-Dec, <0.5", Albuquerque turns much wetter in Jan-Mar. It's not guaranteed, some years remain very dry (2012-13, 1995-96), but its more likely than not historically to turn wet. Will be interesting to see whether that happens in March, or January, its disfavored to happen in February.

DRXtElmUEAUpN1E.jpg

 

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Regarding storm #1: mostly 06z Thu to 18z Thu. The 12z and 18z GFS averaged out at 0.3" or possibly 0.4" QPF for areas of Denver to Cheyenne. this could mean 3-4.5" for low elevations (with some 15:1 ratios in there.) High elevations are not much different. Canadian and Euro are lower, at 0.15" to 0.2". That could still mean 3" with 15:1 ratios.

Storm #2 could be more uncertain at this point. The GFS has this happening generally Saturday 00z to Saturday 12z. The Kuchera snow ratios are 25:1 if you look at Pivotalweather.com.  QPF of 0.4" might be possible.

Given all that happened last year, expect a forecast bust.

I have to go to DIA in between storms, but not during them, I guess. Wish me luck. I change planes at O'Hare on Friday with not much time to spare. And you always want a bit of extra time at Chicago O'Hare.

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Had a 44 minute connection at O'Hare last month on United, with one flight arriving at C27 and the other leaving from B6, so about the longest walk for a domestic same-airline connection. Fortunately had a seat near the front of the first flight, everything was on time, and the fast walk took me 8 minutes. So all was well- thank goodness for an on time first leg!

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It seems that the models have reduced snow amounts. The NWS is calling for 1-3" for the Front Range tomorrow.  Saturday should be snowy (2-4") with a high of 16. So that's pretty cold, but very typical for a cold shot at this time of year. The cold temps on Christmas Eve may be in the range of 0 to -5. The cold temperatures seem more reasonable now, then those insane Euro forecasts posted earlier in this thread. I was pretty sure that -25 at Denver wouldn't verify!

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This is a random thing, but the current US temperature anomaly pattern is reminiscent of "wet South" Marches to me. For the right image, the NE and SW anomalies need to be rotated clockwise, but its pretty close otherwise. The left image has the hottest areas where it is quite cold in Dec 2017 (Gulf Coast), and the coldest areas where it is quite warm in Dec 2017 (Los Angeles is on fire, ND/Montana are +15 in places month to date)

IKt5sNv.png

TZmEURi.png

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