Mountain West Discussion

[Chinook]

It seems about time to start a new discussion thread for winter. Around here, the temperatures here have been pleasantly above 60 since 10/17. We had our heavy snow and frost on 10/14, which killed a lot of the tree colors, particularly the cottonwood tree colors. The GFS/Euro have showing some snow for the Front Range on Halloween, one week from today. 

[mayjawintastawm]

That would be a fun Halloween! So far, this fall reminds me almost exactly of last fall, except I didn't lose any tree limbs so far this fall due to snow. I hope this winter doesn't remind me of last winter.

[Chinook]

CoCoRAHS shows that up to 1.80" of rain fell in Albuquerque. That's some helpful water for a semi-desert in a drought.

[raindancewx]

It rained here from about 3 pm yesterday to around Noon today. Pretty wonderful. I'm still amazed at how much rain Phoenix has gotten. We're well above average in Albuquerque, but no where near as near all-time record rainfall as Phoenix is. 

[Chinook]

I am trying to figure out the synoptics on the Tuesday-Wednesday (Halloween) storm system. The Euro doesn't seem to want to cooperate with the GFS on the 500mb trough or the total QPF. Generally, I would say northeast Colorado has a chance at 2-4" of snow at low elevations during this time frame, with possible rain. Things could change. 

[raindancewx]

This year is going to be a good test for my theories on March. When it rains a lot in August & October, we tend to send snow in March. We had 2.59" in Aug+Oct, pending anything on 10/31. At 2.70" and up, 27/29 of the following Marches have snow here, even if it is only 0.1", and most are much more than that. In all other years, around 55% odds of snow in March. The two exceptions are 2006-07 (28" from Oct-May, 21" in Dec), and 1978-79 when it snowed in May.

If you make a grid of August & October rains here, high/low, for each of the two months, a wet October after a dry August is actually the pattern that most favors March as the heaviest snow month between Oct-May. This pattern produces March as the snowiest month 35% of the time historically, all other years, only 11%. The El Nino years with a high October for precipitation after a low August are pretty interesting as a group - 1941,1957,1965,1969,2004,2009,2015. In fact, a blend of 1957, 1972, 2004, 2004, 2004, and 2015 is an almost perfect re-creation of rainfall by month here since July.

Back to 1931, it has only snowed 3 inches or more in Albuquerque in March one time since 1931 with low-solar conditions in July-June. Back to 1892, it is only two times. In high solar years, it is more like a 30% occurrence, v. a 3% occurrence in low solar years.

The low August, high October El Nino rain years do look like this October for what its worth, and you even have El Ninos with major hurricanes hitting the Gulf Coast in 1941, 1957, 1965, 1969, and 2004.

https://en.wikipedia.org/wiki/1941_Texas_hurricane

https://en.wikipedia.org/wiki/Hurricane_Audrey (1957)

https://en.wikipedia.org/wiki/Hurricane_Betsy (1965)

https://en.wikipedia.org/wiki/Hurricane_Camille

https://en.wikipedia.org/wiki/Hurricane_Ivan (2004)

Just for comparison, here are the wet August, wet October El Nino winters.

Here are the wet August, dry October years.

Finally, years when Aug & Oct are both low for precipitation in El Ninos.

[Randy4Confluence]

Incredibly boring pattern here in N. CA with this Eastern Pacific ridge killing us. Anyone have idea when it finally begins to break? For awhile, the GFS was trying to break it in the long range ( 240+hours ) but over the last few days it keeps the beast in place with temporary breaks. 

[raindancewx]

My 10/1-10/28 high is 67.3F. October should finish as the first month with below average highs against 1931-2017 (or 1951-2010) in Albuquerque since August 2017.

Long-term average high is 71.3F (1931-2017). The most recent 30-year period has few hot Octobers and some very cold Octobers, so I prefer the longer-time frames. 

We had over an inch of rain this October, with more possibly on Halloween. Over an inch in October here tends to mean the PDO will be fairly near 0 for Nov-Apr on average. If the PDO is outside the +0.5 to -0.5 range for Nov-Apr, Oct tends to be much drier.

[Chinook]

Tuesday night to Wednesday mid-day, there should be rain changing to snow for lower elevations near here. The snow forecast may be tricky from Denver/Boulder southward to Trinidad/Raton NM. Some areas under 6000 ft. could get over 6" of snow, but I think it will be less than that for downtown Denver, and also near me. The GFS/NAM show temps of 35 with snow falling on Wednesday morning in the cities.

 Synoptically, it's mostly just a cold front with convergence at the Rocky Mountains, nothing very unusual.

 

[raindancewx]

Looks to me like I'll get to finally test my "Raindance Rule". The Raindance Rule says when Albuquerque gets 2.70 inches of rain in August & October, there is a near guarantee of snow in March in the city. The last time the city had 2.70" in those months was in 2006, prior to March 2007, the last wet March in Albuquerque. The rule failed that year, despite 5 inches of snow in February and 21 inches in December. But the other other time it failed, the city had 2 inches of snow in May and a lot from Jan-May, close to 10. 

In the 1931-2017 era, 29 years have had 2.7" or more in August & October before winter. Of those, 27 had snow the following March. All other years (58) are around 55% odds of snow for March. Heavy rain in October after little rain in August is often a pattern that happens before a) Major Gulf Coast hurricane hits (check) and b) Heavy March snow....so we'll see.

[Randy4Confluence]

One  sign that CA finally cools down in  early November is a -PNA forecasted by the various ensembles. 

http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/pna.shtml

 

It's not out of the ordinary that Ca experiences such a warm October, but as time moves forward from now into November, the kinds of temps that CA has been experiencing grows more unprecidented. For those of us who are pulling for rainy and cooler weather in CA, let's hope this pans out! 

 

[raindancewx]

The Canadian shifted to a wetter NW in its latest run despite increasing the El Nino strength. I wonder if it is seeing a -PDO pattern now? The warm tongue by Japan seems more intense than the warm ring by Alaska.

[ConiferMtnMan]

On 10/28/2018 at 8:35 PM, Chinook said:

Tuesday night to Wednesday mid-day, there should be rain changing to snow for lower elevations near here. The snow forecast may be tricky from Denver/Boulder southward to Trinidad/Raton NM. Some areas under 6000 ft. could get over 6" of snow, but I think it will be less than that for downtown Denver, and also near me. The GFS/NAM show temps of 35 with snow falling on Wednesday morning in the cities.

 Synoptically, it's mostly just a cold front with convergence at the Rocky Mountains, nothing very unusual.

 

We ended up with ~6” at 8400’ sw of Denver. Was expecting a bit more, but was happy enough with the result. Unfortunately, this is the time of year when I leave for work in the dark and get home in the dark, so I have no pictures to share. I’ll definitely share whenever we have a weekend snow.

[Chinook]

In the next several days, it looks like 3 snowstorms will happen in the Rockies with a northwesterly flow aloft, and bring snow to NW Wyoming and a pretty good section of Colorado above 8000 ft. The GFS runs today have had some 2.0" of QPF at Rocky Mountain N.P. and Steamboat Springs within 7 days. This would be 20" to 40" at these higher elevations, with some 7000-10000 ft areas of getting 10" or better.

[raindancewx]

November, March, April would be my best guesses for above average snow in Denver and really most of CO, and it does look promising for November at least. Don't see the storm track being ideal in winter itself. But with Fall/Spring snows lumped in with winter, July-June snow is probably above normal in Southern Colorado and only a bit below to the north.

The data I have for Albuquerque, in El Nino years, after a wet October shows a very strong signal (+70%) for a wet April the following year. Only one real dry April of the ten.

[aggiegeog]

From Facebook reports, NM resorts are still a couple weeks from opening, the northern NM resorts picked up 8-16" of snow from this storm.

[Chinook]

I was just hearing some weird noises here... 60mph winds at the foothills. Low pressure, cold front, heavy snow showers in the mountains right now.  Right now we are getting the highest measured wind gusts in Fort Collins since 4/17.

[raindancewx]

Very windy here today. I'm a bit amazed it hasn't hit 32F in the morning here yet, given we've had several days with highs in the 40s and low 50s already. Been either too windy, too humid, or too much daylight so far, and obviously the heat island doesn't help.

The NOAA PDO value today came in at -0.71 for October. If you look back at all the El Nino winters since 1931, that is an unusual value for an El Nino. Closest years are 1994, 2004, 2006 - i.e. in the -0.31 to -1.11 range in October. For the better JISAO PDO data, I think you have to assume the PDO is around -0.2 for October 2018, which is still unusual for an El Nino, especially since this event really took off in October.

The blend of 1994, 2004, 2006 kind of looks like the CFS for winter...but its the CFS.

[Chinook]

I always have to remind myself about the meaning of the PDO. It seems like it should change once a decade, by definition, but that's not true. Clearly the (positive) PDO anomalies are highly correlated to (positive) El Nino anomalies in the general sense. Here's the PDO generalized map (correlation of SST vs PDO index for winter months) on the left and the current SSTA on the right. Why isn't the PDO index positive now? The only major trouble spot is the fact that the central Pacific east of Japan out to 150W is not cold at all

[raindancewx]

To me the PDO is the measure of the heat imbalance in the North Pacific and the associated water current / air pressure patterns. If the NE/NW Pacific isn't substantially warmer than the other, the PDO is "near neutral", kind of the PDO version of not being in a La Nina or El Nino. You can have a +PDO if the waters by Alaska are -2F v. average but the waters by Russia are -5F v average, and you can have a -PDO if the waters by Russia are -2F v. average, but the waters by Alaska are -5F v. average.

For October, those waters by Russia and Japan were as warm or warmer than the waters by Alaska. The Western half of the North Pacific looks like 2000, 2005, 2008, 2010, etc. Kind of looks like 1994 and 2004 too, but its definitely more common in the La Nina / -PDO phases.

The top +PDO Novembers look like this -

So I think you have to assume on net, for Nov-Apr, the PDO is neutral, even though it will probably slowly shift toward being more positive through winter/spring on/off. One indicator I use for the PDO being Neutral in Nov-Apr is rainfall in Albuquerque in October - you very rarely see over an inch of rain here in October if the PDO isn't Neutral the following Nov-Apr. I think in the +PDO years, we are already getting moisture starved storms from the NW/CA coming inland, and in the -PDO, we are just hot and dry with the monsoon dead and storms still too far north, but also no help from Tropical Pacific hurricanes. If the PDO is near 0, we tend to get a lot of help from the East Pacific. This is the data I have -

18/28 of wet Octobers (1 inch or more in Oct. Average is 0.84") will be followed by a neutral PDO here.

18/33 of Neutral Nov-Apr PDO periods will be preceded by a wet October, only 10/54 positive/negative PDO periods will be preceded by a wet October - this is statistically significant on a difference of proportions test, i.e. highly unlikely to be due to chance.

[finnster]

I read recently an analysis of upcoming US weather patterns by Larry Cosgrove in his weekly Weather American Google discussion group - a great source of info BTW.  His analysis was none too encouraging for snow and winter weather enthusiasts (which no doubt includes most of here).  Larry indicated that after mid-November a good portion of the US will shift to a tranquil, warm weather pattern - perhaps lasting until early JANUARY .  In this case I hope he is wrong but if he isn't that is a good chunk of winter - gone.

I was hopeful the developing El Nino would fire up some good moisture and storms for Colorado - especially the mountains.  It seems this El Nino is having trouble actually becoming one, and at least so far is not having much effect in bringing storms to the western US.

Any related thoughts from experts here are appreciated!

[raindancewx]

I think he's basically right nationally, the pattern will be cold for a week or ten days, then get mild for a while. I do think at least in the SW we'll get some storms in Nov and then probably a lot of precip in Dec. If we manage to pull off a cold Oct and a cold Nov here for highs, that is pretty rare in ABQ, and a lot of the amazing/legendary El Ninos show up, including 1972-73. Cold Oct in ABQ (66.8F, -4.5F) already happened, and the next week or so looks cold, so it's probably 60-40 that it'll happen. The years that show up include major hurricanes hitting the Gulf Coast too, which I see as a a good sign that things are similar.

Even without 1972-73, the signal is very strong for major late snows here if we get the cold Nov with the cold Oct.

Snow	Oct	Nov	Dec	Jan	Feb	Mar	Apr	May	Total
1957	0.0	0.0	2.9	2.3	0.5	7.3	0.0	0.0	13.0
1969	0.0	0.0	1.1	0.0	2.7	3.3	0.0	0.0	7.1
1972	0.0	2.9	1.2	9.5	1.8	13.9	8.1	0.0	37.4
1986	3.2	0.6	0.2	4.9	4.9	0.2	2.2	0.0	16.2
2004	0.2	1.7	0.3	0.0	0.0	4.2	0.5	0.0	6.9
Mean	0.7	1.0	1.1	3.3	2.0	5.8	2.2	0.0	16.1

[Chinook]

Short-term forecasts show about 1" to 3" of snow along the I-25 cities and basically nothing in the rest of the Colorado plains. Possibly up to 6" in the mountains for Sunday. There should be an east-west area of snow of Albuquerque to Amarillo.

[raindancewx]

The only year on record with snow in Albuquerque on 11/12 is...wait for it....

1972

Most severe winter in the SW in like 100 years.

 

[finnster]

15 hours ago, raindancewx said:

I think he's basically right nationally, the pattern will be cold for a week or ten days, then get mild for a while. I do think at least in the SW we'll get some storms in Nov and then probably a lot of precip in Dec. If we manage to pull off a cold Oct and a cold Nov here for highs, that is pretty rare in ABQ, and a lot of the amazing/legendary El Ninos show up, including 1972-73. Cold Oct in ABQ (66.8F, -4.5F) already happened, and the next week or so looks cold, so it's probably 60-40 that it'll happen. The years that show up include major hurricanes hitting the Gulf Coast too, which I see as a a good sign that things are similar.

Even without 1972-73, the signal is very strong for major late snows here if we get the cold Nov with the cold Oct.

Snow	Oct	Nov	Dec	Jan	Feb	Mar	Apr	May	Total
1957	0.0	0.0	2.9	2.3	0.5	7.3	0.0	0.0	13.0
1969	0.0	0.0	1.1	0.0	2.7	3.3	0.0	0.0	7.1
1972	0.0	2.9	1.2	9.5	1.8	13.9	8.1	0.0	37.4
1986	3.2	0.6	0.2	4.9	4.9	0.2	2.2	0.0	16.2
2004	0.2	1.7	0.3	0.0	0.0	4.2	0.5	0.0	6.9
Mean	0.7	1.0	1.1	3.3	2.0	5.8	2.2	0.0	16.1

Thanks - interesting numbers, I would take those comparison years for snow in a heartbeat,compared to the last few we've had.  As for November and December in the rest of the country I don't give a hoot what they get - I just want to see the West and Southwest get some storms, and start the recovery from the last couple of dismal snow years....

[finnster]

13 hours ago, Chinook said:

Short-term forecasts show about 1" to 3" of snow along the I-25 cities and basically nothing in the rest of the Colorado plains. Possibly up to 6" in the mountains for Sunday. There should be an east-west area of snow of Albuquerque to Amarillo.

Thanks Chinook - here's hoping the I-25 cities get at least something!

[Chinook]

Yesterday, we had a high of 39, low of 17 at Fort Collins. (average of 28.0) On December 21st, the average high/low is 42 and 17 (average of 29.6). (1981-2010 climatology, I believe.) So we were colder than our lowest daily average of the year.

[Chinook]

GFS/NAM now have 4" for Denver, maybe 5-6" for Colorado Springs now. So maybe this could be a bigger impact for the biggest metro areas.

[raindancewx]

I'm looking forward to testing my regression for El Nino Albuquerque high temperatures this winter. Won't know for sure how it did until the ONI value for Dec-Feb comes around March 7. The basic idea is the coldest winters (by highs) for Albuquerque are (relatively) strong El Ninos following (relatively) strong La Ninas with low solar activity. The actual Nino 3.4 surface temps in El Nino don't really correlate at all here with high temps in the winter. The input this year will be something like +1.2C for ONI - if the Euro is right, -0.9C for ONI last winter, and then 6 sunspots for July-June on an annualized basis. When I attempted to re-create those conditions, any blend that is close on all three conditions tends to be somewhat (-1F) to very cold (-4F) for the winter. When I tested the regression on 1931-2017 El Ninos, the three things explain around 65% of high temperature variation, and the same math worked at about the expected level for 1892-1930 El Ninos. It will sometimes fail miserably in volcanic El Nino years (1963, 1994) and get the high w/in 1.8F for all other years.

The math formula itself, using +1.2C, -0.9C, 6 sunspots says 45.6F, +/-1.8F is the most likely outcome for this winter, i.e. -2.2F to -5.8F, with -4F most likely. If the ONI comes in weaker, the numbers rise pretty quickly. That being said, it isn't hard to see what it has such a cold winter:

You can pretty easily re-create 2014 with the three variables as an example of why I have confidence in this method. With slightly higher sunspots and a slightly weaker El Nino than the blend, you'd expect maybe 50F for 2014-15, and the actual was 51.4F.

[Chinook]

We've got about 3.5" of snow right now, with some decent size flakes/aggregate flakes.