Mountain West Discussion

[Chinook]

It looks like KFTG radar got repaired ahead of schedule.

[raindancewx]

That next system on 12/12 looks a bit more promising than it did yesterday along the NM/CO border. Still in the time frame of the most recent early December SOI crash. There should be something around 12/19 too - GFS already has a storm in that time frame, it's +10 days from the SOI crash recently.

[raindancewx]

12/10 system definitely had some juice with it.

GFS is fairly optimistic for Saturday too.

[smokeybandit]

I got 1/4" of my 2-3" today. Maybe I'll double that for Saturday.

[raindancewx]

The models haven't been loading today, but the 3-km NAM is in through Saturday at least, and at this range it should be quite good. More decent snows for Western Colorado and Northern New Mexico.

[Chinook]

My area got about 2" yesterday

it could always be worse--- Denver, Colorado , December 1990 high and low temps

[raindancewx]

1990 actually showed up in the CPC analogs today. Nice to see the East bathing in warmth on their outlook. I'd imagine the warmth is pretty muted though. Not really expecting a whole lot of snow south of NYC east of the fall line but it would keep the warmth in control for a bit in the East. It's like a ~12 days in 90 year frequency for Philadelphia to get even six inches of snow in December though.

[mayjawintastawm]

This weekend: 3.9" total (1.2 then 2.7").

With this week's storm and next week's temps, the East Coast may have some flooding on their hands just in time for Santa. Weird.

[Chinook]

Totals:

Dec 10-12: 0.17" precip, 1.6" snow
Dec 12-13: 0.08" precip, 1.0" snow

[raindancewx]

I'm generally happy with my national snow outlook. But I wish that area along the border of IL/MO would fill in.

[smokeybandit]

1/4", 2.1", 1.2"

But low on all 3 systems

[raindancewx]

Not bad for Western Colorado yesterday.

[Chinook]

My area got about 0.5" of snow last night, and Denver got around 2".

Saturn and Jupiter will be (or were) the closest that they have appeared in our sky in many years.

 

[smokeybandit]

looks like some crazy boring weather the next 2 weeks for NE Colorado

[Chinook]

Tomorrow, there will be something that I expect several times during a La Nina winter: high winds, from a northern jet stream disturbance. Southeast Wyoming and Larimer County (6000-9000 ft) have high wind watches tomorrow.

[raindancewx]

Date	Tahiti (hPa)	Darwin (hPa)	Daily Contribution	30 day Av. SOI	90 day Av. SOI
20 Dec 2020	1011.45	1005.80	10.02	12.80	9.49
19 Dec 2020	1012.11	1002.50	30.57	13.03	9.54
18 Dec 2020	1012.34	1002.05	34.10	12.68	9.35
17 Dec 2020	1013.64	1003.35	34.10	12.22	9.08
16 Dec 2020	1013.54	1004.30	28.65	11.67	8.85

Keep your eyes on the end of the month. That's a pretty massive drop for one day. The SOI is still positive, so it's probably a northern stream system with some pop if something is going to come through. The SOI crashed pretty hard in a very positive month about this time (12/18-12/19) in 2018 ten days before the end of the month system.

2018 352 1014.64 1006.70   21.90
2018 353 1013.25 1008.05    7.68

This is late 2016 -

2016 355 1010.63 1002.35   23.66
2016 356 1010.94 1003.25   20.60
2016 357 1009.60 1005.95   -0.36
2016 358 1007.23 1006.85  -17.33

Pretty hard to find 20 point drops in a day at this time of year.

[Chinook]

17 hours ago, raindancewx said:

Keep your eyes on the end of the month. That's a pretty massive drop for one day. The SOI is still positive, so it's probably a northern stream system with some pop if something is going to come through. The SOI crashed pretty hard in a very positive month about this time (12/18-12/19) in 2018 ten days before the end of the month system.

Some of the ensemble means do indeed have a trough in Utah/Colorado-- about what you want to see, I suppose, if you were going to put your hope in any storm in Colorado at 240 hours in the future.   

edit:

to a degree, this month has showed signs of looking like an El Nino upper level pattern, with positive PNA and cooler temperatures in the Southern Plains and Southeast, and even, nearly a true Miller-A storm for the East Coast.

[raindancewx]

The Euro still has a system in the time frame you'd expect after the SOI crash. I would expect something to come through.

I realized yesterday there is monthly data for the West Pacific Oscillation. We flipped from an extremely negative WPO in October to a positive WPO in November-December. That's useful for preventing winter warmth out here. I hope it continues in Feb-Apr, because it's a very strong cold signal for the Southwest in that time frame. The WPO correlation to the US in October and what actually happened in October is basically uncanny, it's a powerful little index at certain times.

 

[Chinook]

Today, my area has a few lenticular clouds and mostly clear skies. I am hoping to see Saturn and Jupiter next to each other in about 1-2 hours. Yesterday, my area had about 39 degrees in mid-afternoon when other areas were warmer, with adiabatic mixing. Today, my area is up to the upper 50's.

 

edit: 

I got lucky. Sometimes the lenticular cloud at sunset is tough to find. I also saw Jupiter and Saturn in the binoculars a few minutes ago.

 

[Chinook]

wind warnings and blizzard warnings. NWS point forecast for me shows 52mph wind gusts before midnight.

[Chinook]

14 years ago (December 20-21, 2006)

 

view from apartment building

[Chinook]

It looks like we really may have something to track over the next 6 days. There could me more snow in Kansas than at my place.

[Chinook]

My place dropped from 60 degrees to 29 degrees. Look at South Dakota-- they were in the mid 60's, then blizzard, apparently 49.7 degrees colder.

[raindancewx]

Date	Tahiti (hPa)	Darwin (hPa)	Daily Contribution	30 day Av. SOI	90 day Av. SOI
24 Dec 2020	1010.81	1006.15	4.88	15.22	9.62
23 Dec 2020	1010.84	1004.25	14.89	15.16	9.75
22 Dec 2020	1012.31	1004.30	22.26	14.40	9.75

Big drop again. Another time to watch will be 1/3. Probably a weaker system though.

 

[raindancewx]

Looks like another good snow event for Western Colorado and then the Plains. We'll get some good snows here in the mountains too. The Euro should start to have a good idea on precipitation totals for the majority of this event this time tomorrow. Large areas of NM & AZ may be able to pull out a wetter than average December if this verifies or trends wetter.

 

[Chinook]

The storm is getting closer. This is the Euro depiction that shows that northern Colorado would get 1-3" with sort of a warm advection sector to the storm. The higher elevations of Colorado will get 3-6" or better with upslope, and maybe over 6" as the upslope continues for perhaps some hours (beyond what's shown on this chart). As for the Midwest, Nebraska/Iowa and the Upper Midwest will have the potential for snow over 6"-12". Kansas and possibly northern Missouri could have some sleet or freezing rain. It seems several models have shown low snowfall for eastern Colorado, and this is kind of disappointing, considering the 500mb is so close to the right spot.

[snowfan789]

Well, some models at some times recently have shown a bit more promise in the Front Range for the next system. Others -- like the GFS -- not so much, generally. Seems like a lot of possibilities remain on the table currently.

On a different note, where in AZ and NM may finish December with above average precip? The state of the snowpack is pretty bad throughout most of the West, and downright terrible in much of AZ and NM. https://www.wcc.nrcs.usda.gov/ftpref/data/water/wcs/gis/maps/west_swepctnormal_update.pdf 

[raindancewx]

I would say the SW portions of NM and SE portions of AZ have a shot at finishing above normal if you believe the European depictions with the storm. You have to remember, a lot of valleys in NM/AZ only see about 0.50-1.0" of rain + melted snow in December. There was an extremely narrow snow band around here on 12/2 that probably dumped 0.25-0.50" as snow in some spots, and then we had the more widespread storm later in the month. That's why some areas show up as above normal here:

The new Euro may be completely different in 45 minutes, but this run from earlier would be enough to push portions of SE AZ/SW NM to a wetter than average December.

[Chinook]

Here is the 00z Euro snow totals chart up to the point -before- the 500mb low regenerates a snowy surface low in the southern Plains. Overall, the GFS, Euro, and Canadian have come into better agreement on QPF in Colorado, where snow should be in my area from 12z Monday- 06z Tuesday. Note: See MO/AR/OK/KS thread for discussion of possible large southern plains ice and snow storm.

[raindancewx]

The 3-km NAM still has this as a decent snow event for Western Colorado and the high terrain of northern New Mexico. It's with the Euro/GFS trends for the rest of NM/AZ though, showing very little south of I-40.