Mountain West Discussion

[mayjawintastawm]

And we have record-breaking warmth in Denver during the cold season once again (will we touch 80? 1 degree off as of 1:53 pm), which can only mean one thing: snow within 24 hours. 

[Chinook]

I don't know what's the most impressive temp of the day: 82 at Ainsworth, Nebraska. 84 at La Junta Colorado (higher elevation, but lower latitude.) 67 at Cheyenne at 6100 ft above sea level (1 degree away from daily record). Possibly 79 at Denver?

Fort Collins was 76.3, so I'm thinking that this will break a record, and it will be recorded as 76 or 77 on Fort Collins daily temp.

[mayjawintastawm]

Got to 81 at DEN, hottest November temperature ever recorded! (yeah yeah, I know, DEN has more variability, used to be at Stapleton, etc.) Even more impressive that it's the 28th.

Low this AM was 47, so if the front doesn't drop the temp lower before midnight we are +31 compared to normal for the day.

I wonder what the highest DFN is for a day in Denver. I bet it isn't far from this. No idea how to look that one up.

If we were -31, the mean would have been +2 F. Brr.

[Chinook]

The temp has dropped from the mid-70s yesterday to around 42 degrees. By the way, the 12z Euro has a pretty big snowstorm for mid-Colorado down to mid-New Mexico at 7.5 days.

[donsutherland1]

Yesterday, Denver had its latest 80° reading on record. That means 2017 had both the earliest and latest 80° temperatures on record in Denver.

Earliest: February 10, 2017 80° (old record: March 16, 2015 81°)

Latest: November 27, 2017 81° (old record: November 16, 2016 80°)

[raindancewx]

One of the nice things about ABQ is we're west of the big mountains, so we haven't been above 70F in the city here since mid-month, and we're pretty clearly done with 70s til February /March and 80s until March/April.

General idea in my analogs was warmth in Nov, really to Dec 15, as Nov 16-Dec 15 came in quite warm, then maybe a very cold month, or maybe a very hot month - that is the key period - no "near normal" for Dec 16-Jan 15 showed up.

[mayjawintastawm]

1 hour ago, donsutherland1 said:

Yesterday, Denver had its latest 80° reading on record. That means 2017 had both the earliest and latest 80° temperatures on record in Denver.

Earliest: February 10, 2017 80° (old record: March 16, 2015 81°)

Latest: November 27, 2017 81° (old record: November 16, 2016 80°)

Wow. so only 74 calendar days for the non-warm weather "season". And the "summer" of 2017 wasn't even particularly hot, and severe weather was less than usual. Kind of hard to make any kind of unifying sense of this, other than a lack of moisture driving at least some of it.

[ConiferMtnMan]

3 hours ago, Chinook said:

The temp has dropped from the mid-70s yesterday to around 42 degrees. By the way, the 12z Euro has a pretty big snowstorm for mid-Colorado down to mid-New Mexico at 7.5 days.

You can pretty well bet on that snowstorm next week. I’m getting concrete flatwork poured next Wednesday. That’s got to work better for bringing on a snowstorm than washing cars.

[finnster]

22 hours ago, Chinook said:

I don't know what's the most impressive temp of the day: 82 at Ainsworth, Nebraska. 84 at La Junta Colorado (higher elevation, but lower latitude.) 67 at Cheyenne at 6100 ft above sea level (1 degree away from daily record). Possibly 79 at Denver?

Fort Collins was 76.3, so I'm thinking that this will break a record, and it will be recorded as 76 or 77 on Fort Collins daily temp.

This November has been hard to take - we're breaking the wrong kind of records IMHO.  I was fortunate enough to grow up here on the northern Front Range and got to experience some great fall and winter storms throughout the 1970's and 80's.  To my way of thinking those were the glory years - I miss 'em.  I don't need to have non-stop storms from late October through April to be happy, but good gosh what we're experiencing now is pathetic.  Pushing 80 degrees in late November around here just ain't right

[raindancewx]

November down here is highly responsive to the NAO/AO. We will occasionally torch with a -NAO here in November, but if it returns Jan-Apr we get much colder. Would imagine its somewhat similar up in CO. The Atlantic, whether you look at the NAO or the AMO seems to be a strong indicator for when we get big snow down here - we've basically never had 3 inches of snow in Dec in cold/neutral AMO years, but it happens almost every year in warm AMO years. Opposite is true in January. Nov/Feb/Mar are favored here when the AMO is near neutral.

Solar seems to have impacts on snow in Spring here, for whatever reason, when the PDO (Mantua) values are near 0 with an El Nino we can get big time blizzards down here. We tend to get multiple snowy Novembers in a row after big volcanic eruptions too, for whatever reason.

 

 

[Chinook]

Quote

Finnster:This November has been hard to take - we're breaking the wrong kind of records IMHO.  I was fortunate enough to grow up here on the northern Front Range and got to experience some great fall and winter storms throughout the 1970's and 80's.  To my way of thinking those were the glory years - I miss 'em.  I don't need to have non-stop storms from late October through April to be happy, but good gosh what we're experiencing now is pathetic.  Pushing 80 degrees in late November around here just ain't right 

You are right. If you don't count Sep-Oct-Nov 2009 snowfall, then the Sep-Oct-Nov snow totals of many years since 2000 have been low. 1981-2000 average fall snowfall is 13.1". Check this out.

 

[finnster]

13 hours ago, raindancewx said:

November down here is highly responsive to the NAO/AO. We will occasionally torch with a -NAO here in November, but if it returns Jan-Apr we get much colder. Would imagine its somewhat similar up in CO. The Atlantic, whether you look at the NAO or the AMO seems to be a strong indicator for when we get big snow down here - we've basically never had 3 inches of snow in Dec in cold/neutral AMO years, but it happens almost every year in warm AMO years. Opposite is true in January. Nov/Feb/Mar are favored here when the AMO is near neutral.

Solar seems to have impacts on snow in Spring here, for whatever reason, when the PDO (Mantua) values are near 0 with an El Nino we can get big time blizzards down here. We tend to get multiple snowy Novembers in a row after big volcanic eruptions too, for whatever reason.

Thanks - very interesting. So many factors involved.  For the northern front range of CO in particular, we did very well for snow in the late 1970's - 1980's, which featured AMO in the cool phase and the PDO in the warm phase.  I keep checking on the AMO phase (been warm for many years now) but overall it does not appear to be shifting to a cool phase - although by some projections it is about time for it to start that shift (there has been a persistent cold blob in the north Atlantic but does not seem to be propagating much).  Who knows, maybe a big volcanic eruption will trigger a change.  Of course in NM you may not necessarily be rooting for a cool AMO....

 

 

[finnster]

9 hours ago, Chinook said:

You are right. If you don't count Sep-Oct-Nov 2009 snowfall, then the Sep-Oct-Nov snow totals of many years since 2000 have been low. 1981-2000 average fall snowfall is 13.1". Check this out.

 

Thanks - very revealing graphic, September snows have been non-existent for the past 17 years!  And the rest of the fall has not been very snowy during these years - with the exception of 2009.  It seems these falls have not been unusually dry, just lacking cold air to produce good snowstorms.

[raindancewx]

For the June-November period, 2012 remains easily the best historical match to my observed highs and precipitation in 2017, compared to all years for 1931-2016.

Among the years I used for this winter, local observations at this point imply 2012, 2007, 2005, 1943 as the "strongest matches", in order, with 1932, 2008, 1944, 1996 following. If the blend of the years used were counted as a single year, would be the 19th best match to Jun-Nov out of 86 years, so seems to be working fairly well even with 1944/1996 increasingly looking like bad matches for temperatures.

[mayjawintastawm]

I hope this winter doesn't come out like 2012-3. The late season saved us just in the nick of time to avoid a really dry/snow-free winter. Then again, almost anything would be better than the year we just had.

[raindancewx]

I haven't tested this in other areas, but in Albuquerque during the 27 La Nina events in the 1931-32 to 2016-17 data set, October is by far a stronger predictor of December temperatures than November. If you convert the R values to P values it's not even close, p=0.009 for Oct to Dec, p=0.356 for Nov to Dec.

It failed pretty massively in November after working well in October, but also tends to be colder in La Nina cold seasons here after a warm season with many (>89) hot days (>=87F), which we had this year. My view is arid/semi-arid climates try to maintain constant precipitation/evaporation rates and so w/ less moisture and a very hot Summer in a La Nina, the local climate attempts to compensate in the winter with either a warm/wet winter, or cool/dry winter in La Ninas.

[Chinook]

The 12z GFS brought back the Dec 4-5 storm for areas north of Colorado Springs. I wasn't totally sure that any model run would bring it back.

[raindancewx]

Trend has been erratic but down for NM. Albuquerque isn't Yuma, not a fan of these 50,60 day stretches without any precipitation. 60 days is a massive stretch w/o precip down here by historical standards, although it did happen in some of my analogs at slightly different time frames. At least we'll be trending colder for a while after Dec 3. The record warmth for November with the dryness is no fun.

[mayjawintastawm]

Looking like November at DEN will be about #10 warmest (roughly +6.5) and tied for #2 least snowy (trace). Here's to a different December.

[raindancewx]

The Canadian (which correctly had a very warm Nov in the West outside the far north) is showing a cold December for much of the area, a big change from its prior run. That blob of cold over NV, with a somewhat warm East is more or less what my analogs (from Oct 12 in my outlook) had the whole winter, should it verify. Do expect it to be a recurring part of the pattern at least, even if it doesn't end up as the dominant feature.

[Chinook]

The NAM/GFS have some snow with the cold front in northern Colorado at about 18z Monday - 00z Tuesday (5:00PM Monday.) There still seems to be some variance, but the models are showing the most of the snow will be in Wyoming. I expect this to be a relatively typical 4-12" of snow above 9000 ft in this time period of Monday-Tuesday. Metro areas still have a chance of getting plowable snow. Most likely this will be trace to 3" for the metro areas.

[Mercurial]

Drought over up here according to the UNL drought monitor.  Just in time for what looks to be a dry December, ugh.  

[ValpoVike]

1 hour ago, Chinook said:

The NAM/GFS have some snow with the cold front in northern Colorado at about 18z Monday - 00z Tuesday (5:00PM Monday.) There still seems to be some variance, but the models are showing the most of the snow will be in Wyoming. I expect this to be a relatively typical 4-12" of snow above 9000 ft in this time period of Monday-Tuesday. Metro areas still have a chance of getting plowable snow. Most likely this will be trace to 3" for the metro areas.

3" is a stretech for plowable   Man, we really need some snow soon.

[raindancewx]

It really does seem like the "warm north of less warm/cold" waters in the Atlantic and Nino 1.2 work best at predicting how dry the SW will be in La Ninas. Right image is definitely closer to now, with the major caveat that neither composite has the extremely warm waters off of Western Mexico like this year. The warmth west of cold in the Atlantic in the mid-latitudes seems to support a wet winter/spring in the SW even with a La Nina. Warmth north of cold on the other hand, supports dry winters in La Ninas....and its what I'd say we have this year. Nino 1.2 is also much colder. All that said - the pattern does still have elements of "warm west / cooler east" in the Atlantic, its just less clearly defined than last year, so not expecting a super-dry winter here, still think we get an inch of precipitation, which is only - 20 to -30% v. the long-term means.

[mayjawintastawm]

16 hours ago, ValpoVike said:

3" is a stretech for plowable   Man, we really need some snow soon.

If we're lucky, we might get enough for my neighbor with the electric cord powered snowblower (why do they even make those things??) to scrape along his sidewalk with a generous 1/2 inch.

A couple years ago I read something that predicted Denver's climate to approach El Paso's by around 2050. Can't remember where. Sure feels like it.

[raindancewx]

El Paso is like 15F warmer than Denver with half the precipitation, not to mention the elevation differences. With help (El Nino, volcano, low-sun) they will see one to two feet of snow randomly down there in a given month. Pretty sure El Paso had 2 feet of snow in April 1983, which is mind boggling to me.

It does seem like even down to 28N or so, it tends to snow every year at elevations above 6,500 feet, with snow still probable/frequent even down to 3,500 feet.

[Chinook]

At this point, the models really aren't even giving us any fantasy snow. At least the NAM has 9" for the mountains above 10000 ft tomorrow. (Higher for 3-km NAM.) NWS is not even that impressed with tomorrow's storm at high elevations.

[raindancewx]

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

[finnster]

Is winter (or at least December) going to be a no-show?

In recent visits to my favorite weather sites (this one, Open Snow Colorado, Weather5280) I'm getting the idea that December (and possibly the entire winter) may be a no-show for Colorado and the western part of the U.S.  The pattern that is setting up now for at least the next couple of weeks is certainly not encouraging for any storms in this region.  This, after a record-breaking warm November is pretty discouraging for those (few) of us that actually like to see some cold and snow.

Although not directly related to Colorado weather, I do visit the Weather West site once in a while, which is California-oriented.  They just posted this write-up on the ridiculously resilient ridge (RRR) that haunted them up until last winter with heat and dryness, and now seems to be establishing itself again. 

http://weatherwest.com/

The reason I bring this up is that long-lasting ridges like this (in the wrong places) can really deter storms from getting anywhere close to us with any regularity.  Last month seems to have started a trend that I sure hope doesn't last all winter

[raindancewx]

Its kind of impressive seeing how strong and far south the sub-tropical jet is at the moment, its a La Nina isn't it? I don't remember it being over El Paso in early December in 2010. Southern areas of the SW did have big snows in February 2011 during the great cold wave and there was some good snow in Dec 2011, but its still unusual.