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2020-2021 Winter: Early Thoughts

Fountainguy97

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Well it didn't take too many days of summer to get me in the mood for fall/winter. I just worked up some preliminary analogs and figured this would be a good start to the VERY early look at winter.

Obviously we start with the ENSO pattern. After matching up a list of past ENSO patterns that evolved in similar time/fashion/magnitude I narrowed that down just by a simple comparison of the global SST's during those years. I came up with 6 years that fit a fairly similar to very similar resemblance to the June Global SST pattern of 2020. I left a couple outliers in just to keep it diverse should ENSO shift toward fall.

One major assumption I made was to look for weak la nina or cool neutral years that followed an el nino period. I excluded a few that went into strong la nina as thats likely not going to happen this year. I also left in a couple that actually went back into warm territory by winter.

So I loosely based this off the assumption that we are looking toward a weak nina or cool neutral. But left the option open to a trend back toward warm neutral.

Here is the current forecast for ENSO which we all know can change every second and are often completely wrong.Nino 3.4.gif


GLOBAL SST COMPARISON OF ANALOGS

Analogs: 92-93, 95-96, 03-04, 05-06, 10-11, 12-13

Purple zones are similar to 2020. Brown designates ENSO which mostly correspond to the way 2020 is evolving (some lag by a few months) Red is a zone that stands apart of the 2020 map. The older maps are more coarse so who knows how similar they truly are.

Anyway, in general these years all share some very similar global SST patterns.


June SST comparison.pngjune 3 comp.png


One wildcard is the PDO region. A pretty good mix of + and - in here.
Numbers here for those interested. I've included the year before and after my analog year. So for examples since its confusing: the first group my analog is 92-93. I included 91 as the precursor year to help identify similar long term patterns. And each number is a month left to right from January-December. SO each analog is the middle row right number (before the solid line) and the first two numbers on the third row. This is the December-February period. This is similar for PNA and QBO.


PDO.png


QBO and PNA

I'm just going to throw the charts in here. They came out pretty similar. Obviously they don't need to be exact but this is a general idea of where these years went.

QBO its easy to see red numbers on the first line, blue in middle, red on bottom. Pretty similar progression. Not perfect.

Remember: typically a -qbo rising positive is the best for a cold winter in the east.

QBO Comparison.png


PNA: This is a wash. BUT several of these winters had a month predominately + PNA.

Remember: +PNA is our friend in winter (Ridge west US trough east US)
PNA comparison.png


Hurricane Ace Comparison

A VERY interesting point in these analogs is how active all of them were. I promise the years had no meaning to me. I started just picking years off an ENSO graph that had similar curves and magnitudes and came out with this.

I'm skeptical of the hurricane activity to winter activity analog but some people live and die by it. SO if an active cane season = active winter we could have a great test of that this year IF we end up very active.

Hurricane Ace Comparison.png

US temp and precip maps from analogs in next post :)
 
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Analog Temperatures

Overall we end up around normal. Cool start, warm middle, cool finish. REMEMBER: La nina DOES NOT just mean automatic torch. I like to think of it as anything other than a strong nino/nina is weak enough for us to find periods of weather that are not typical for the ENSO state. The closer to neutral we are the more I like to picture us swinging between the typical ENSO driven weather patterns. Of course there are multiple ENSO patterns that we can get specific on.

If we do see a weak Nina or cool neutral this outcome is very likely. I highly highly favor a "mellow" winter that is neither a major torch or major cold. The cool/warm periods will likely cancel out to near normal. Maybe 0+2 given recent warm trends past 2010.

All this is dependent on ENSO and the direction it takes over the next few months. As we complete more months of 2020 I will continue to compare these analogs on a monthly basis to see how we are playing out.

December composite.pngJan composite.pngFeb Composite.pngDec-Feb composite.png



Analog Precip

As expected in La Nina we are a bit dry.

Dec precip composite.png
Jan precip composite.pngFeb precip composite.pngDec-feb precip composite.png


So there it is! We would take this look 100%. Others can dig in further on these years into the 500mb patterns etc if you guys want!

I just wanted to throw out a ton of raw data to get us started! A long way to go as always.
 
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Torch, southeast ridge, more high shear low cape severe events than winter storms, I wanna bet we end up getting locked up in a pattern with a suppressed GOA ridge, -PNA, +EPO, +TNH, SER, the SER has just been so dominant for the past 5-6 years and I don’t that changing (this post is a half joke) depends if JB screws us over with his BN map
 
Torch, southeast ridge, more high shear low cape severe events than winter storms, I wanna bet we end up getting locked up in a pattern with a suppressed GOA ridge, -PNA, +EPO, +TNH, SER, the SER has just been so dominant for the past 5-6 years and I don’t that changing (this post is a half joke) depends if JB screws us over with his BN map

it wouldn’t surprise me. We really have fought the SER so much recently. I also feel like we can never seem to get the +PNA when we need it. Which those probably go hand in hand. We are getting it. Just not when we have a favorable storm system lol.
 
I’m a bit encouraged by how this Niña thing is doing. I don’t think Nino’s are going to do anything, with the surrounding waters being warm. However, below average ENSO SST’s, should be interesting. I don’t know about you guys, but 2017-2018, which was a Niña year, may be my favorite winter of the decade with the exception of February. One storm in Dec, two in Jan, three in March, 1 in April. With a Nina, we won’t have to worry as badly about the pacific jet, and would be dealing with a more active polar jet. With these Enso events, it’s pick and choose between an active polar jet, or subtropical jet, and frankly, a lot of us are sick and tired of the subtropical jet.

It is also worth mentioning the stance on the PDO. I know several
people over the years who have mistaken the +anomalies to be another case of the warm blob. From the looks of it currently say that the configuration has no real impact. One may argue a -PDO because of the cool waters off the coast, however those are merely just cooler waters than the blob.

I think that the EPO, will be the most crucial part of the winter, I definitely think someone/myself, should look into what leads to more positive/negative events. Coupled of course with the PNA.
 
I've also read (somewhere) that the winters after solar minimum (heading into a new cycle) tends to have more blocking. **Some have said we flipped to the new cycle (25) in late December 2019, but it currently can't be certified.

(but)Another way to look at this is to throw science out and just say "We're due for a big winter".
 
it wouldn’t surprise me. We really have fought the SER so much recently. I also feel like we can never seem to get the +PNA when we need it. Which those probably go hand in hand. We are getting it. Just not when we have a favorable storm system lol.
Years back we debated which of the indices were more critical for the SE. (my opinion)The last couple of winters have proven the PNA to be absolutely critical. -PNA kills our chances for winter storms.

 
Great Analysis!

Im going to predict above average temps and below average snowfall. Seems to be the new norm lol
 
I'll take a 10/11 and run like **** until I'm ready to go back to North Georgia to live (honestly, 17/18 as well), but I do think there was another factor that played in that cancelled 10/11 from being your typical warm La Nina (as IIRC, it wasn't weak).
 
I’m a bit encouraged by how this Niña thing is doing. I don’t think Nino’s are going to do anything, with the surrounding waters being warm. However, below average ENSO SST’s, should be interesting. I don’t know about you guys, but 2017-2018, which was a Niña year, may be my favorite winter of the decade with the exception of February. One storm in Dec, two in Jan, three in March, 1 in April. With a Nina, we won’t have to worry as badly about the pacific jet, and would be dealing with a more active polar jet. With these Enso events, it’s pick and choose between an active polar jet, or subtropical jet, and frankly, a lot of us are sick and tired of the subtropical jet.

It is also worth mentioning the stance on the PDO. I know several
people over the years who have mistaken the +anomalies to be another case of the warm blob. From the looks of it currently say that the configuration has no real impact. One may argue a -PDO because of the cool waters off the coast, however those are merely just cooler waters than the blob.

I think that the EPO, will be the most crucial part of the winter, I definitely think someone/myself, should look into what leads to more positive/negative events. Coupled of course with the PNA.
The past few years when it seems like we’re gonna get a -EPO, tropical forcing moves into a bad phase, and instead of the -EPO, we just straight up get a +TNH, and get locked with a suppressed ridge around the gulf of Alaska, Which forces the PNA negative, idk why this bad timing thing happens often but it’s annoying
 
My initial prediction for KATL DJF is +3 (trend is your friend), which is still ~33 colder than this summer. Have to go solidly warmer than normal as long as the Indonesian region remains so warm (no end in sight) and also taking into account continued GW. 30 year normals are deceiving as they now represent solidly colder than normal for all practical purposes. So, a +3 is like a new normal. Looking forward to cool dry days and chilly nights no matter how far above “normal”.

I also predict that the average forecast will as usual end up significantly too cold due to eternal optimism for cold.
 
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Initial thoughts are winter ends up on average above normal but we likely have 1/2 months that are near to below but one well above normal that pushes the average positive. My biggest concerns are the PV and tropical forcing driven by the same SSTs we have seen the last couple of winters.
 
My prediction is for winter so warm that the birds never migrate south, tomatoes are fresh on the vine into December, freezes are confined to the foothills and mountains, no snow south of NYC or below 5000 feet. I loved being on here, this post will definitely be getting me banned.
 
Warm waters will absolutely dominate the maritime continent. We might see some of the warmest SST’s we’ve ever seen down there this winter. MJO 4,5,6 will reign supreme. Nothing else will matter. Above average winter temperatures up and down the eastern seaboard. However, I do think we time a banger of a long duration snow event. Will it be east or west of the mountains? Stay tuned! ??
 
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