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Chinook

Mountain West Discussion

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3 minutes ago, The Waterboy said:

Denver, Fort Collins, Greeley.    

Well, the great thing about the northern front range is that regardless of the weather down below you can always drive up to RMNP and visit a ton of snow. :)

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2 hours ago, ValpoVike said:

Well, the great thing about the northern front range is that regardless of the weather down below you can always drive up to RMNP and visit a ton of snow. :)

Very true.  It’s on the agenda to head up to Estes Park one day.  RMNP is amazing!  

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Today's Euro shows that the storm will provide about 2-3" of snowfall all over the plains of Colorado on 12/28 (96 hours) but this is somewhat of an outlier. I think it handles the 500mb low differently than the GFS and Candian.

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Some ensemble members of the GFS and Euro show some hope for snow in Denver. These must have a bit of a different look at 500mb than the regular GFS at this time.

Interesting fact: NWS-Fairbanks is forecasting -46F for the Tanana valley this week.

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For Saturday-Sunday, the NWS is expecting 1.5"-3.9" of snow for the Front Range cities. There is a winter storm watch east of DIA. Heavier snow towards northeast Colorado and Nebraska, as well as southern Colorado and northern New Mexico.

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On 12/24/2019 at 2:55 PM, Chinook said:

Some ensemble members of the GFS and Euro show some hope for snow in Denver. These must have a bit of a different look at 500mb than the regular GFS at this time.

Interesting fact: NWS-Fairbanks is forecasting -46F for the Tanana valley this week.

Yeah, kind of interesting. NWS is now predicting a couple inches for the suburbs E of Denver and DIA, with more the farther east you go. I can't remember a storm quite like this in our 10 winters here, where something comes up from the south and west- it either has been a miss 100 miles east, or a bigger hit.

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2 hours ago, mayjawintastawm said:

Yeah, kind of interesting. NWS is now predicting a couple inches for the suburbs E of Denver and DIA, with more the farther east you go. I can't remember a storm quite like this in our 10 winters here, where something comes up from the south and west- it either has been a miss 100 miles east, or a bigger hit.

We should be close to the 500mb/700mb lows, but without a strong upslope component. So upward motion will not be concentrated on the foothills for very long. Then stronger lift will begin farther east as the surface-to-700mb low intensifies to the east, out near Goodland and into central Kansas. By the way, it looks like the Euro had another (minor) victory on this one, as the GFS had the snow to the east of us for several runs.

NWS already has 8-10" for northern Nebraska through western Minnesota with this storm.

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The GFS has 12" of snow for Akron CO (Washington County, CO) and the NAM has 1" and the NAM-3km has something like 2"-5" in the county. This is madness!

This is mixed precipitation madness that has been happening today in KS and Nebraska:

wVUi3ce.gif

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Forecasts for this storm were kind of a mess. Simultaneously more moisture advection than forecast - much higher dew-points - and then less actual precipitation at the same time. The line of showers that came with the cold front went literally due east until the Rio Grande River, and then went Northeast, missing most of Albuquerque, so I got literally no rain or snow.

My winter forecast was premised on near average to wet conditions in the SW, despite few storms with a lot of precipitation. That still looks about right. Fall was well below average for precipitation and had fewer than average wet days, until November saved it. December has had two days with 0.1" or more precipitation in Albuquerque. I have a statistical regression for winter precipitation here, it said 2.10", +/-0.8" for winter in the city, at 95% certainty based on hindcasts. We're at 0.27" through 12/27. The signal is pretty strong for a wet January, around 0.75" for Albuquerque (double normal) based on how wet November was. Following the 10 wettest Novembers, January was wet nine times. Following the 20 wettest Novembers, January was wet sixteen times. November 2019 was the wettest November in over 100 years here. Somewhat weaker signal for a wet February too.

It's very early, but if the wet January verifies, I'd also expect May to see the usual weather insanity, but amped up to 11 this year, with large hail, blizzards, tornadoes, cold snaps, heat waves, rain and thunderstorms for NM & CO and the High Plains. Nov-Jan wetness in Albuquerque is a strong predictor of an active May. The 2.26" from Nov-Dec 27 is already a top 20 Nov-Jan period for wetness locally in the last 100-years, with five weeks to go. A top five Nov-Jan is pretty likely here. Those Springs would be 1941, 1979, 1992, 1993, 2005. 

The CFS seems to want to roast the middle of the country for January based on the entrenched dryness. I don't really buy the dryness it shows for the West in January though.

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Pretty big area of the US +5F or more, if taken literally. That little blue area in Mexico makes me think the CFS isn't really "seeing" past the first 5-10 days of the month. The snow storm for Mexico will probably not be enough for that one area to be cold if everything around it is warm.

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Snow and wind really picking up again here after 2.5" earlier today. Seems like there is upsloping from I-225 south to Monument, based on radar. I don't think it will last long but it's impressive right now.

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Storm reports show up to 5" - 6" in some parts of the Denver metro, with over 6" at the foothills/Palmer Divide. Also, up to 8" at Pine Bluff, Wyoming. It must have taken a long time. Here in Loveland, snow had mainly ended when I last posted (12 hours ago), we had some downslope wind off the Cheyenne ridge, with weak radar returns, so almost nothing happened beyond 10:00AM. This might be something like a 48-hour (near-blizzard?) storm for eastern South Dakota.

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The CFS has trended to a cold January for WY/CO/NM. I'm not sure I buy it, but it is nice to see. If you wanted a recent set of years that look like its forecast, you can do January 2013/2017 as a blend. I prefer a more El Nino blend, so I did 1906, 1952, 1958, 1993, 2019. The CFS has a dry West for January, which I don't really buy at all, at least for the WY/CO/NM zone. I have January 1952/1958 in there, as 1951/1957 are top SOI matches to Oct-Dec in the past 90 years, and then 1992/2018 are in there because they look like the January forecast as a blend and were in my winter forecast as analogs. I threw in 1905 for some other reasons. I'm expecting the Southwest get more active when the cold begins to move out.

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The Canadian has a powerful La Nina developing Apr-Jun 2020, which it didn't show before. Long-term the Canadian has the PDO going pretty strongly negative too.

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It's also more on board with a dynamic cold West / hot East pattern than the CFS. It's closer to the 2013/2017 blend than the El Nino blend. Outside the Northern Plains where it went super warm, the Canadian forecast was basically solid for December - I'd give it a B+.

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Thanks Raindancewx! Always interesting food for thought.

Trying to remember last season to figure out a calendar year 2019 snow total. I didn't write it down, just tallied it in my head... grr. I'm guessing we had somewhere around 80 inches of snow, with 41.0 since 10/1 (4.2 on 12/28). Not bad at all.

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If we go by the prior min, the solar cycle is about to bottom out. 2019 had 3.6 sunspots/month, down from 4.2 in 2008. Absolute min was 2.2 in the year ending May 2009 in the prior cycle. I find that certain types of unusual events are far more likely to happen in the US below 55-sunspots/month annualized, at statistically significant levels over long-periods. I don't think it changes total heat on Earth much, just the distribution of it, mostly via effects on clouds. 

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Albuquerque just had its coldest year since 2008. All the years at the min are actually pretty cold here. We had the 28th coldest annual high since 1931. Lows are not really impacted by solar at all, and were still real warm.

City had 10.6 inches of snow in 2019 - most since 2015. I'm pretty sure Albuquerque has had more snow so far that NYC, Philly, Baltimore and DC combined this cold season. Outside the NW, I think Western Snow Pack and Reservoir numbers overall are pretty strong heading into 2020.

The precipitation portion of my outlook has been pretty good so far, so I'd expect a more active January than December. Probably will be when/if the big Eastern heat wave comes since MJO phase five is pretty wet in the Southwest in January. MJO getting to phase four around 1/6 is similar to 2005, 2007, 2013.

Image

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9 hours ago, mayjawintastawm said:

Thanks Raindancewx! Always interesting food for thought.

Trying to remember last season to figure out a calendar year 2019 snow total. I didn't write it down, just tallied it in my head... grr. I'm guessing we had somewhere around 80 inches of snow, with 41.0 since 10/1 (4.2 on 12/28). Not bad at all.

I have since 2017 kept snowfall records for my backyard, and we received about 115” in relatively elevated western Lakewood in calendar year 2019. Don’t and can’t know how that ranks historically. But it’s probably roughly top 10 since 1900ish based on Boulder’s records (the most relevant reference point I’m aware of). I was surprised by what the math showed — this has been a snowier calendar year than I realized. Still can’t help but be irked by December’s pattern and the very dry signals I have so far seen for early January east of the mountains. Still can’t really figure out what to root for pattern-wise east of the mountains. The projected negative pna seems like it should be at least ok in theory but, still, models indicate dry dry dry for at least the next 10 days, on the heels of a quite dry December.

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19 hours ago, snowfan789 said:

I have since 2017 kept snowfall records for my backyard, and we received about 115” in relatively elevated western Lakewood in calendar year 2019. Don’t and can’t know how that ranks historically. But it’s probably roughly top 10 since 1900ish based on Boulder’s records (the most relevant reference point I’m aware of). I was surprised by what the math showed — this has been a snowier calendar year than I realized. Still can’t help but be irked by December’s pattern and the very dry signals I have so far seen for early January east of the mountains. Still can’t really figure out what to root for pattern-wise east of the mountains. The projected negative pna seems like it should be at least ok in theory but, still, models indicate dry dry dry for at least the next 10 days, on the heels of a quite dry December.

We need to have something more specific than simply a negative PNA index number. We need to have a trough that develops near the West Coast and tracks toward here UT and CO (Four Corners), with perhaps even a ridge just off the West Coast. The PNA index doesn't capture that well, but the index could be negative when that happens. On the other hand, we could get a lot of cold air on the Plains and have upslope event with more arctic air and less of an organized 500mb trough. The PNA or NAO indices may not capture that well. In rare circumstances (like an El Nino,) we could use a large California 500mb low to track toward us, via the Four Corners.

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MJO phase five at high amplitude mid-month should be good for NM & CO for moisture. My original analogs for winter, in my October forecast had 1/12-1/16 as a storm time frame that showed up in multiple years. That looks pretty good. GFS has had something coming through in that range for a few runs now, and the big SOI crash last night supports it....and obviously the MJO should be in phase five by then.

 

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Some snow is depicted through Friday Morning for NM/CO on the GFS and Euro. I'm leaning toward ~30F, 0.20" as snow here. With no East Wind, that's around two inches of snow. Looks like Thursday Night - Friday Morning mostly.

ImageImage

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Nothing particularly substantive to add. But, to state the obvious, what a quite horrible pattern for the CO Front Range since early December. No clear end in sight. No significant precip. No real cold. Just downright oppressively sunny and boring. Ugh. That is all.

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Nothing is really happening here, as the cold air won't lock in. Thursday, my area had a high of 59, which is the highest since the big snow in November. In the models, the consensus is that the developing 500mb storm system on Thursday-Friday is pretty good, but downsloping wind will prevail as it passes by here and creates a huge storm in the Midwest. My area still has some snow in the shade left over from November 25th-26th, like a huge mass of icy stuff next to the driveway.

The Pacific Northwest snowpack is building, and low elevation areas are getting rainfall to diminish drought conditions. By my estimate, the high Cascades have gotten 8 ft - 15ft of snow since January 1st.

03wBIsH.jpg

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The idea in my winter forecast for this pattern was that the seasonal totals for the SW (NM, AZ, CO, UT) would more or less be above average, but it would be a smaller than normal number of storms that got us there. November saved Fall here, with close to two inches of liquid equivalent Nov 16-30, pushing Fall to +30% here for moisture.

The precipitation pattern is essentially 1953-54, but occasionally, 1992-93/2004-05 interject with wetter storms to break up the dryness. A lot of the super warm mid-January periods in the NE (70ish in Boston) showed up in my precipitation analogs - so I don't think we'll stay quiet too much longer. The event on the Euro below is within five days and keeps trending up. I don't know that I buy the front range getting shadowed yet. The way the moisture is forecast to move through New Mexico still looks wrong on the models to me. As depicted below, the Euro would more or less verify the "wet January" idea I've had since December for New Mexico. It's our driest month here - doesn't take much. 

Nationally, the US temperature pattern Jan 1-12 looks like Sept 16-27 roughly. So if the November part of the pattern is to repeat, I'm expecting it Feb 25 - March 5.

Image

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If you buy these two images as similar, and recognize Dec looked like 8/16-9/15, the "exciting" part of the pattern, late November, should return around week 4 February to week one March. Timing wise, should gel with the final push of the subsurface warmth to the surface in Nino 3.4 if you look at the animation.

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