Wild Speculation for Winter 20 -21

[John1122]

4 hours ago, Mr. Kevin said:

John, if we see anything wintry, it will be sleet or fzr imo. Arctic fronts that stall once it encounters the se ridge.

You're in a better place for that to happen that most of us.  Western areas may not see anything this year but I think you'll probably have the most chances for getting cold that sticks well enough to have wintry precip. 

[Mr. Kevin]

40 minutes ago, John1122 said:

You're in a better place for that to happen that most of us.  Western areas may not see anything this year but I think you'll probably have the most chances for getting cold that sticks well enough to have wintry precip. 

It would be nice for all of us at some point to see winter weather this winter.

[Carvers Gap]

Grabbed this from the MA forum.  The Capitol Wx Gang has released its winter outlook.  I found it fairly interesting.

https://www.washingtonpost.com/weather/2020/11/18/washington-dc-winter-outlook-2020-21/

[Holston_River_Rambler]

One thing I've been thinking about the past couple of days, goes back to the discussions of the wild fires and aerosols in the lower strat. Disregarding the whole talk of volcanic winter Masiello brought up a while back, I wonder if there will be some impact on MJO convection. I remember in 2018- 19 there was some talk of the SSW or split or whatever it was, forcing some cooler air towards the equator at in the 30mb and up range and that this might have helped fuel some of the convection over the dreaded Maritime Continent region. 

It was this post from Masiello that got me thinking about it:

 

Convection over the Indian Ocean has been ok, the past couple of weeks and obviously tropical cyclones have also been healthy this year ,so not sure if there is a meaningful correlation.  

[nrgjeff]

Unfortunately the Wall St. Journal does not offer a comparison to Mt. Pinatubo 1992 which was the last aerosol event to actually impact temperatures. 

Carry on with much above normal temps this winter. Strato vortex is really locked up tight. 

[Carvers Gap]

@raindancewx, pretty remarkable post in the MA forum.  I am going to tag you in our winter spec thread even though your post is about the upcoming early Dec pattern.  Our pattern thread is focused on the storm as it should be.  But wanted to look past that a bit.  How did the rest of that 58-59 winter finish up?  For the rest of you all, REMARKABLE similarities to what is being modeled for December.  Just trying to get your opinion on what happens next....

 

[raindancewx]

My idea for the winter has always been that you need a couple years with a warm North Pacific in the analog blend to match how the oceans look. I added in 2012 and 2019 to do that, since they both have low sea ice, and were colder by Peru than the date line at the equator in the Fall. In 2019 specifically, you actually have the warm patch at 45N/150W just like this year does.

It's a stormy volatile pattern that ends up somewhat warm in the East and somewhat cold in the West in December. That's been the idea. Everything I can think of supports it: November +NAO La Nina supports it, low-sea ice extent cold ENSO supports it. Both of those actually look like November quite strongly.

The "desert ENSO constant" supports it. Essentially if you do the Koppen classification math out here for calculating aridity, you'll evaporate/lose 3x the amount of moisture that falls in a July-June La Nina, so if you have exceptionally hot/dry conditions in Summer, you need a lot of help to move wetter toward that constant, and it will tend to come in winter, since La Nina is strongest as a dry-signal here in Spring.

The 1959-60 winter has some fluky snowstorms pretty far south (including two feet where I live in December). My guess would be Dec and March would be the time frame for good eastern snows if 1959-60 ends up a good match to the winter. February 1960 is extremely cold nationally, and March 1960 is extremely cold in the East, so I don't really expect it to be a good match overall. It looks pretty reasonable for December though. It's pretty similar to December 1988. On the CPC maps, I think 1988 is probably a better match anyway. When I did my forecast I gave a long list of how I tiered analogs. The B tier analogs like 1988 should be good temperature matches for a lot of the US a lot of times, I'm just less sold on them for precipitation matches. I've been pretty happy with either 1995 or 2007 as the correct match for Fall for a while now, even if the timing is usually off. November 2007 definitely looks close to this year.

[Carvers Gap]

1 hour ago, raindancewx said:

My idea for the winter has always been that you need a couple years with a warm North Pacific in the analog blend to match how the oceans look. I added in 2012 and 2019 to do that, since they both have low sea ice, and were colder by Peru than the date line at the equator in the Fall. In 2019 specifically, you actually have the warm patch at 45N/150W just like this year does.

It's a stormy volatile pattern that ends up somewhat warm in the East and somewhat cold in the West in December. That's been the idea. Everything I can think of supports it: November +NAO La Nina supports it, low-sea ice extent cold ENSO supports it. Both of those actually look like November quite strongly.

The "desert ENSO constant" supports it. Essentially if you do the Koppen classification math out here for calculating aridity, you'll evaporate/lose 3x the amount of moisture that falls in a July-June La Nina, so if you have exceptionally hot/dry conditions in Summer, you need a lot of help to move wetter toward that constant, and it will tend to come in winter, since La Nina is strongest as a dry-signal here in Spring.

The 1959-60 winter has some fluky snowstorms pretty far south (including two feet where I live in December). My guess would be Dec and March would be the time frame for good eastern snows if 1959-60 ends up a good match to the winter. February 1960 is extremely cold nationally, and March 1960 is extremely cold in the East, so I don't really expect it to be a good match overall. It looks pretty reasonable for December though. It's pretty similar to December 1988. On the CPC maps, I think 1988 is probably a better match anyway. When I did my forecast I gave a long list of how I tiered analogs. The B tier analogs like 1988 should be good temperature matches for a lot of the US a lot of times, I'm just less sold on them for precipitation matches. I've been pretty happy with either 1995 or 2007 as the correct match for Fall for a while now, even if the timing is usually off. November 2007 definitely looks close to this year.

Interesting stuff.  Now the years for the winters are the years for those winters' Decembers, right?  For example, 1995 is short 95-96?

[Carvers Gap]

1 hour ago, raindancewx said:

My idea for the winter has always been that you need a couple years with a warm North Pacific in the analog blend to match how the oceans look. I added in 2012 and 2019 to do that, since they both have low sea ice, and were colder by Peru than the date line at the equator in the Fall. In 2019 specifically, you actually have the warm patch at 45N/150W just like this year does.

It's a stormy volatile pattern that ends up somewhat warm in the East and somewhat cold in the West in December. That's been the idea. Everything I can think of supports it: November +NAO La Nina supports it, low-sea ice extent cold ENSO supports it. Both of those actually look like November quite strongly.

The "desert ENSO constant" supports it. Essentially if you do the Koppen classification math out here for calculating aridity, you'll evaporate/lose 3x the amount of moisture that falls in a July-June La Nina, so if you have exceptionally hot/dry conditions in Summer, you need a lot of help to move wetter toward that constant, and it will tend to come in winter, since La Nina is strongest as a dry-signal here in Spring.

The 1959-60 winter has some fluky snowstorms pretty far south (including two feet where I live in December). My guess would be Dec and March would be the time frame for good eastern snows if 1959-60 ends up a good match to the winter. February 1960 is extremely cold nationally, and March 1960 is extremely cold in the East, so I don't really expect it to be a good match overall. It looks pretty reasonable for December though. It's pretty similar to December 1988. On the CPC maps, I think 1988 is probably a better match anyway. When I did my forecast I gave a long list of how I tiered analogs. The B tier analogs like 1988 should be good temperature matches for a lot of the US a lot of times, I'm just less sold on them for precipitation matches. I've been pretty happy with either 1995 or 2007 as the correct match for Fall for a while now, even if the timing is usually off. November 2007 definitely looks close to this year.

The '59 December analog is just uncanny at 500.  1995 SST look in the Pacific is super similar - was kicking that around earlier this week.  Since that is the Holy Grail of winters here, I have not mentioned it.   But the big warm pool in the NE PAC is there during a La Nina as well.  

We have used some analogs from the 50s recently as well.  Think '54 was kind of a running joke for a while as we broke record after record(high temps) during the fall of 2019.  Crazy stat for TRI, 2019 and 1954 hold HALF of the hight temp records for the month of September with 15 combined records.  Those same two years hold 8 of the records for October with four apiece.  So, for the months of September and October, those two years hold 23 records out of 61 days.  

[raindancewx]

I name the winters by the year they start. My actual winter blend was 1995, 2003, 2007, 2012, 2019. I'm less confident on the weighting I used (2007 x5, 2012 x2, others x1), but unweighted it worked well in October. For 11/1-11/25, the actual high is identical to 2007 in Albuquerque (63.4F), and when I rank all years in the past 100 for precip and highs for June-Nov, 2007 is easily the best match overall out here.

This is what I had. https://www.scribd.com/document/479516526/Winter-2020-21-Outlook

There are already some issues with it: I assumed an ACE of 135, and based some of the pattern idea off 95-175 years. But the ACE is more like 180 now. The raw blend also had 4.8 inches of snow where I am, but we had 4.4 inches in October (all-time monthly record), and statistically we're far more likely to get multiple months topping four inches of snow here in one Oct-May season if we top 4 inches in an "off-season" month, i.e. Nov, or Mar-Apr, it's a common El Nino trait here. A lot of volcanic and Neutral winters here see huge snow dumps in November, so I kind of wonder if the October snow is something similar with aerosol stuff from the western fires this year - but I doubt it is that. The October system had incredible moisture too, a lot of the west side of the city had 8-14 inches of snow after being near 80 degrees a few days before.

Since the long-term snow average is 9.6" but we average 6.2" in an average Nov-May La Nina, it's pretty likely we'll finish with above average snow here (~55/45 using La Nina years). Of course, there is no La Nina since at least 1930 with 4 inches of snow here in an off-season month, so we could also destroy the average pretty easily. A lot of La Ninas (~1/3) finish under 4.4 for the entire cold season, including 2017-18, 2016-17, 2010-11, 2008-09, 2005-06 just in the last 20 years.

To me, the low-sea ice similarity is uncanny to November so far -

Same for the +NAO La Nina patterns in November - that's not real typical. It's 1956, 1999, 2007, 2011 as a blend if you use only top third +NAO monthly values with a La Nina. That goes to a somewhat similar look to how December looks.

[Carvers Gap]

9 minutes ago, raindancewx said:

I name the winters by the year they start. My actual winter blend was 1995, 2003, 2007, 2012, 2019. I'm less confident on the weighting I used (2007 x5, 2012 x2, others x1), but unweighted it worked well in October. For 11/1-11/25, the actual high is identical to 2007 in Albuquerque (63.4F), and when I rank all years in the past 100 for precip and highs for June-Nov, 2007 is easily the best match overall out here.

This is what I had. https://www.scribd.com/document/479516526/Winter-2020-21-Outlook

There are already some issues with it: I assumed an ACE of 135, and based some of the pattern idea off 95-175 years. But the ACE is more like 180 now. The raw blend also had 4.8 inches of snow where I am, but we had 4.4 inches in October (all-time monthly record), and statistically we're far more likely to get multiple months topping four inches of snow here in one Oct-May season if we top 4 inches in an "off-season" month, i.e. Nov, or Mar-Apr, it's a common El Nino trait here. A lot of volcanic and Neutral winters here see huge snow dumps in November, so I kind of wonder if the October snow is something similar with aerosol stuff from the western fires this year - but I doubt it is that. The October system had incredible moisture too, a lot of the west side of the city had 8-14 inches of snow after being near 80 degrees a few days before.

Since the long-term snow average is 9.6" but we average 6.2" in average Nov-May La Nina, it's pretty likely we'll finish with above average snow here (~55/45 using La Nina years). Of course, there is no La Nina since at least 1930 with 4 inches of snow here in an off-season month, so we could also destroy the average pretty easily. A lot of La Ninas (~1/3) finish under 4.4 for the entire cold season, including 2017-18, 2016-17, 2010-11, 2008-09, 2005-06 just in the last 20 years.

To me, the low-sea ice similarity is uncanny to November so far -

Same for the +NAO La Nina patterns in November - that's not real typical. It's 1956, 1999, 2007, 2011 as a blend if you use only top third +NAO monthly values with a La Nina. That goes to a somewhat similar look to how December looks.

Nina's here are generally not great producers of snow, but there are several notable exceptions.  Makes it really difficult to us an analog package here due to that.  Thera are a small group of analogs that are cold and snowy...and buck the trend.  I put my ideas out over the summer.  Had December as normalish(I think...too lazy to go check) with Jan and Feb increasingly warm.  However, I think intrusions of extreme weather(winter) might happen.  Might be some long stretches in the East between those events...but Nina winters in TN have held some surprises.  After seeing our weak El Nino(normally favorable) go down in flames, makes me wonder if choosing analogs right now might be very dependent on the warm pool in the NE PAC and the SSTs west of the equatorial dateline which affect the MJO.   When those SSTs west of the dateline are overly warm, seems to send the MJO into phases 4-6 more frequently which is a torch here.  Probably could add in the IO which sends convection into that areas as well.  Additionally, Typhoon Tip noted that the lack of gradient with SST temps in the PAC might be affecting ENSO stuff...meaning washing out those signals.  

But seriously great stuff and thanks for taking the time to share your thoughts here.  Really enjoyed it.  

[raindancewx]

To me La Ninas are Atlantic driven. If we're really moving to the cold AMO, and I still think we are going to see it mid-decade - then we should start to see much better (colder) La Ninas nationally. 1959 if it verifies was about 4-5 years before the flip to the cold AMO, and that's about where we are now, given the flip to warm was 1995. The hurricane seasons from 1954-1964 are kind of similar to now too, with Hazel, Donna, Hilda, etc. 1961 had a huge system hit Central America super late like this year, and has the QBO/ENSO match you'd want if you like analogs off that stuff. I'd imagine you had (cyclical) low sea ice extent in those Falls too, although still more than now.

[nrgjeff]

European monthlies and CFS monthlies just out are both disasters for snow enthusiasts. Tie it in with the latest discussion in our ENSO thread; and, it looks like a mild winter which will require some luck. What's new in the South? 

I still think the +ABNA phase will offer chances (normal to BN heights SE with above normal heights parts of Canada). Key will be some help from the PNA, NAO or other blocking. Overall though it now looks like cold shots will be brief. I know this is a sentiment shift from my last post in the main December thread. 

Also tied in with our ENSO thread, severe wx in late winter and early spring looks at least normal with a good chance of greater than normal activity. EC monthlies have Plains season (LOL 5-6 month forecast verbatim) quieter than normal; CFS is normal.

So I guess chase early season garbage in case there's no late season. Why am I writing about chasing already? Oh yeah the winter monthlies and SSTs.

[Windspeed]

European monthlies and CFS monthlies just out are both disasters for snow enthusiasts. Tie it in with the latest discussion in our ENSO thread; and, it looks like a mild winter which will require some luck. What's new in the South? 
I still think the +ABNA phase will offer chances (normal to BN heights SE with above normal heights parts of Canada). Key will be some help from the PNA, NAO or other blocking. Overall though it now looks like cold shots will be brief. I know this is a sentiment shift from my last post in the main December thread. 
Also tied in with our ENSO thread, severe wx in late winter and early spring looks at least normal with a good chance of greater than normal activity. EC monthlies have Plains season (LOL 5-6 month forecast verbatim) quieter than normal; CFS is normal.
So I guess chase early season garbage in case there's no late season. Why am I writing about chasing already? Oh yeah the winter monthlies and SSTs.

Yeah you can always live vicariously through New Englanders.