Mountain West Discussion

[finnster]

Checking out

[smokeybandit]

I think every snow forecast for my back yard has busted low so far this winter.

[ValpoVike]

I did ok up here with a bit over 4".  I was expecting 3-6.  Definitely not a big snowfall, but I'll take anything.

[Chinook]

My place got a little over 2", probably like 2.2".

[raindancewx]

The north-central mountains here have been doing OK, but it's not been good elsewhere. The north-central part of the state near the Colorado border did finish pretty close to normal though for December precipitation with the recent system.

[Chinook]

It looks like we've got an El Nino going here with mild Pacific air an important factor in the Dakotas, and cool conditions in the Southwest and Southeast.

[raindancewx]

12 minutes ago, Chinook said:

It looks like we've got an El Nino going here with mild Pacific air an important factor in the Dakotas, and cool conditions in the Southwest and Southeast.

Any idea on how long it will take NWS to switch to the 1991-2020 normals? It'd be weird seeing a month calculated against one baseline, and then a sudden shift to another.

[Mercurial]

Looks like a super lame winter back home in Montana... oh well.

[raindancewx]

One of the long-range theories is that US patterns tend to repeat what happens in the Bering Sea in 14-18 days. I've been real curious for a while now if that 938 mb low SE of Kamchatka in late December is going to be a big storm over New Mexico around 1/14-1/18. I'm mentioning it in this thread because I think the idea is the southern tip of Kamchatka is supposed to correspond to 35N - so this would be an "Albuquerque low", which is often quite good for Colorado.

 

[Chinook]

In related news, the low pressure in the western Aleutians in the Pacific was analyzed at 921 mb at December 31st, 18z. Since it was so late in the day, in UTC, it was indeed January 1st in some part of the Eastern Hemisphere. I have not seen a 921mb low for extratropical lows. I believe the record is 913mb for the North Atlantic. I am not aware of any extratropical lows of this value in the Southern Hemisphere, but there could have been something.

 

Edit: 

Raindance, I wonder when (and if) the models will pick up on such a storm system at some 240 hours out. Perhaps we could say model ensembles already have a hint of a upper trough and surface low near the Great Lakes at 280 hours, and that may be the hint of the connection right there.

[raindancewx]

I actually wrote it wrong up there - it's more like 17-21 days. I did have the timing right though, 12/28, +17 to 21 days is about 1/14 to 1/18. There are some hints of the SOI reversing sharply for a day and the MJO waking up a bit, both of which would probably help. This is what comes up when you Google the timing. I'm not a huge fan of Bering Sea stuff for New Mexico a lot of our storms are essentially clippers or weak cold fronts.

https://www.weatherboy.com/tag/bering-sea-rule/#:~:text=Bering Sea Rule Suggests Warmth%2C Severe Storms Returning in March&text=Meteorologists look at weather patterns,United States come mid-March

[Chinook]

The models now have some agreement on some version of a 500mb low near the Four Corners and snow for northern Colorado on Saturday. ECMWF has the snow farther south around Trinidad CO, moving down toward SE New Mexico. It's possible that this is a storm that could just disappear, as so many have.

By the way, my place hasn't been above 50 since Dec. 26th. They keep saying it will be 50, but the snowcover and lack of mixing has kept us cooler than Cheyenne and Denver at times.

[raindancewx]

The Euro has a lot of light snow still, Canadian is kind of similar. GFS very different. I'm inclined to think this storm will happen, it's just the track. It has the "SOI support" I look for with a big crash 12/31 to 1/1, which is 9-10 days ahead of the precip below as the theory goes.

[raindancewx]

This looks pretty good for New Mexico up to about Denver now? Timing is certainly lined up with the big SOI crash 12/31 to 1/1. Trend is our friend hopefully.

[Chinook]

Some light snow is beginning to fill the radar in northern Colorado. Last night's models showed some values over 2" for this area, which is a little more than previous models.

[smokeybandit]

Got about 2" from yesterday's system. First time we've gotten what was forecast this winter.

Now for the heat wave this week to melt it all

[mayjawintastawm]

1.7" this "storm", 22.6" on the season. Yawn. About average for this time of year, thanks to the early season stuff.

[raindancewx]

The time frame I mentioned above (1/14-1/18) for the Bering Sea Rule is now supported by the recent SOI crashes too (1/18-1/19). The theme this year has been moisture starved northern branch systems, so no reason to deviate from that until proven otherwise.

9 Jan 2021	1011.86	1006.35	4.25	19.34	10.60
8 Jan 2021	1013.12	1005.30	15.13	19.56	10.69
7 Jan 2021	1014.99	1004.95	25.58	19.23	10.68

[Chinook]

My place got about 2.5" on Saturday, with apparently 0.16" liquid equivalent. Every so-called storm has produced 24-hour snow values of 0.6" to 2.6" since November 1st. When are we going to get an actual snow storm? On a related matter, my place got 0.53" liquid equivalent of snow for December, which is somewhere near or perhaps less than the average value for December. The Decembers since I have lived here, Fort Collins has averaged 0.67". I can't even find a "fantasy storm" except for 240 hours on the Euro.

[raindancewx]

The storms in Sept-Oct came through when the WPO was in the opposite phase. Some hints it may flip back by the end of the month. I'd imagine it will be easier for the bigger cold/wet Fall storms in an otherwise warm pattern to recur if the WPO does flip. The subtropical tap may also open up a bit for storms if the pattern really does flip as much as it is supposed to in a week or two. The PNA is forecast to go negative for the first time in what...two months? 

The GFS has been showing something around a week from now, but it does look moisture starved.

[mayjawintastawm]

OK, revealing that I am truly not a met but a frustrated winter precip lover who migrated to an area with a lot less moisture....

The stratospheric warming event being talked about so much frequently leads to big cold air dumps and storminess in the mid latitudes (the "polar vortex"). It seems like this pattern occurs only between about 30 degrees E and 90 degrees W longitude though. I can't find a reason that it isn't more evenly distributed around the Pole. Any ideas why? It's probably obvious but I'm missing some key information. Thanks in advance.

[Chinook]

I added up my precipitation for 2020, and I got 13.05". That's below normal , but Fort Collins-CSU only got 11.87". That's a moderate difference. Denver had 8.74". It's obvious that some areas got lower than 10".

 

80mph may be unrealistic for tomorrow, in the city.

Quote

...HIGH WINDS POSSIBLE ACROSS THE FOOTHILLS STARTING LATE
WEDNESDAY AND ON THE PLAINS STARTING EARLY THURSDAY...

Including Estes Park, Glendevey, Nederland, Red Feather Lakes,
Bailey, Central City, Evergreen, Georgetown, Idaho Springs,
Westcreek, Fort Collins, Hereford, Loveland, Nunn, Arvada,
Boulder, Golden, Lakewood, and Longmont

...HIGH WIND WATCH NOW IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH
FRIDAY MORNING...

* WHAT...Northwest winds 30 to 40 mph with gusts up to 80 mph
  possible.

 

[Chinook]

On 1/11/2021 at 7:25 PM, mayjawintastawm said:

OK, revealing that I am truly not a met but a frustrated winter precip lover who migrated to an area with a lot less moisture....

The stratospheric warming event being talked about so much frequently leads to big cold air dumps and storminess in the mid latitudes (the "polar vortex"). It seems like this pattern occurs only between about 30 degrees E and 90 degrees W longitude though. I can't find a reason that it isn't more evenly distributed around the Pole. Any ideas why? It's probably obvious but I'm missing some key information. Thanks in advance.

I definitely feel that- I saw lots more precip in when I lived in Ohio and Michigan, but weaker snowstorms. So yeah, this longer drought is disappointing. I'd love some rain.

When we get a -NAO pattern affecting North America, the colder air masses can develop in central Canada, but get pushed east, frequently leading to the 500mb heights in the west getting higher.  As you can see, the general expectation of a -AO pattern is correlated to the blue colors in the most of the East and even Central (so that would be colder air), but then it seems to change to orange colors for Utah. 

[mayjawintastawm]

Aha- so it's the -NAO combined with the SSW events. Do big cold dumps of air happen in other places when the NAO is positive or neutral and SSW events happen? Or are they tightly linked?

[Chinook]

I don't completely understand the system. I just plotted the correlation of the AO index to the 850mb temp. As you can see, I included November, since some of our cold shots come in November. I also don't completely understand how a stratospheric warming at over 100,000 feet above sea level can slowly begin to affect the patterns near the surface. The AO index can go quite negative as the stratosphere undergoes large changes. The AO index calculated by the CPC is based off 1000mb height anomalies, essentially the same as SLP anomalies, in the Pacific, North America, the Atlantic, and Europe. The NAO index is calculated based off 500mb heights mostly toward the Atlantic side of things. Either way, the SLP at Greenland and the central-north Atlantic ocean are highly correlated to both the AO and NAO indices. As for us in Colorado the colder air getting into the West is most correlated with a ridge near Anchorage and Juneau, and development of cold air in the Yukon and Alberta. That does not fit into the scheme of the -NAO pattern, as 500mb heights might be quite high for the East Coast into the central-north Atlantic when that happens.

[raindancewx]

The time frame supported by the big system southeast of Kamchatka in late December and the recent large SOI crashes does look like it will have a big storm. Already looks like Albuquerque might get screwed by a big East wind with that system. It is only 4.5 - 6.5 days out though, and the GFS & Euro both show a lot of moisture with it. It looks like a strong system from the Gulf of Alaska so maybe it is pulling in subtropical moisture. I don't really look in detail until we're within 3.5 days of the entire event.

[Chinook]

Sunset tonight

[Chinook]

I just recently said that there wasn't much of a fantasy storm for Colorado-- and that's true. The models have shifted a little bit. Today's models have some agreement in bringing a diving 500mb trough into Arizona, with potential for lighter snows in Colorado and possibly moderate snows in New Mexico.

[ValpoVike]

We had intense winds up here in Glen Haven last night.  On my home weather station I clocked 99mph at 8:40pm, and lost power shortly after.  Some fence damage, and many trees down in the neighborhood especially in the CP burn areas.

[Chinook]

For my place, the wind kicked in maybe after 8PM or 9PM, with some max wind gusts of 51mph at KFNL airport, possibly 40-55mph near me, around midnight. Winds gusts are back up to 40mph now.