The last 4 Stratosphere warmings and US temperatures

[Stormchaserchuck1]

We had a 30-day Stratosphere warming last Winter Feb 14-March 15. 

https://ibb.co/601Xr3H

It did downwell to the troposphere to effect the NAO

https://ibb.co/GT59g8v

Here US temperatures for the most historically effected time-lag:

https://ibb.co/82qyFTz

Before that we had a Stratosphere warming in January 2021

https://ibb.co/JkdhgnK

This is how that one effected temps +time

https://ibb.co/d0zFmC1

We also had one in January 2019

https://ibb.co/Z6CKVjd

Again, a SE ridge pops (+normal-time-to-impact)

https://ibb.co/Y8yhTPR

Feb 13-March 15 2018

https://ibb.co/BcdvyNd

One of our colder ones in the east recently

https://ibb.co/pQTCrh9

Really impacted the NAO +time

https://ibb.co/TmzxvwT

 

Now I will explain the time-lag:

There are great resources through the CDC daily climate composites that allow you to backcheck things going back to 1948: https://psl.noaa.gov/data/composites/day/

In looking at the whole timeset, I found a strong +time correlation to 10mb warmings and -NAO (500mb). It varied at different times in the year:

Stratosphere warming Oct 30-Nov 15 has highest -NAO correlation at +45 days (Dec 15-30)

Nov 15-30 Stratosphere warming has highest -NAO correlation at +40 days (Dec 25-Jan 10)

Dec 1-15 Stratosphere warming has highest -NAO correlation at +35 days (Jan 5-20)

Dec 15-30 Stratosphere warming has highest -NAO correlation at +30 days (Jan 15-30)

Jan 1-15 Stratosphere warming has highest -NAO correlation at +25 days (Jan 25-Feb 5)

Jan 15-30 Stratosphere warming has highest -NAO correlation at +20 days (Feb 5-20)

Feb 1-15 Stratosphere warming has highest -NAO correlation at +20 days (Feb 20- Mar 5)

Feb 15-Mar2 Stratosphere warming has highest -NAO correlation at +15 days (Mar 1-15)

March 1-15 Stratosphere warming has highest -NAO correlation at +15 days (March 15-30)

etc.. They vary in effects to the troposphere at different times of the cold season, but I found I strong correlation +time (since 1948). 

Here are the NAO effects on our temperature +0Day (+40-50% correlation):

https://ibb.co/jDLnWvp

 

Since 2013, and more so 2019, I have noticed a correlation between -NAO and +epo/-pna, and visa-versa. The correlation is ~0.30 since 2013, and ~0.40 since 2019. Early in December, a strong -NAO built, and the correlation held in an El Nino.  Models have 10mb warming peaking around Jan 6th, which would make Jan 25-30 ripe for -NAO impacts, and maybe, therefore, a -pna? The fact that it's an El Nino makes it 75/25 more likely to have a +PNA at that time so we will see what happens.. 

[raindancewx]

The tendency for the more recent Strat Warm events to not be cold in the East is why I've not been super into following it. 

We more or less "know" where it is going to dump cold right? I mean Minneapolis has never had a winter average above like 27F since like the 1930s. It's 35F there in December month to date, and they average about 20F for the winter. Seems like the obvious spot for SSW cold to dump is...the Plains. Again. Since any dump will come during a period when the El Nino is rapidly weakening, I'd expect some SE ridging in response like in prior years. This is all assuming of course that the cold even comes to the US. But I doubt Minneapolis will finish +15F if the record is +7F for their warmest winter in 90+ years.

[Stormchaserchuck1]

I'll include updates about the Stratosphere warming in this thread

We are already hitting Stratosphere warming territory, as of Christmas: (as per the method I used to research historical -NAO correlations):

https://ibb.co/Htm37sB

12-27 is already pretty strong 

https://ibb.co/MRc03C6

Dec 25-27 has a normal/average lag to 500mb of +25-30 days. So that makes the highest probability of -NAO conditions to start on Jan 19. Stratosphere warmings at 10mb usually last a total of 15-45 days. This one seems projected on models to go on pretty long.  

[Stormchaserchuck1]

On 12/29/2023 at 10:24 PM, Stormchaserchuck1 said:

Stratosphere warmings at 10mb usually last a total of 15-45 days. This one seems projected on models to go on pretty long.  

It looks like the long term Stratosphere warming is no longer projected to happen. The problem I think is following the EPS when it has not been a great model. The consecutive runs showing big anomalies was the indicator, but the GEFS now has net negative 10mb anomalies in a week. 

We are still posting +valid warming results in the CDC daily plot for the 4th consecutive day on 12-29

https://ibb.co/zJYVh8m

12 days is what's need to count in my stats as a valid Stratosphere warming event, for the valid NAO correlation.

[Stormchaserchuck1]

The first wave Stratosphere warming occurred Dec 25 - Jan 9th. This was, I would say a 3/10 scale warming. We did get the same kind of effects as the examples above of cold in the US +time, which we are still experiencing now, Jan 20th. -NAO occurred Jan 4-19, so a little sooner than my perfect correlation time. 

Now we are seeing a 2nd wave Stratosphere warming, starting on Jan 13. It's so close to the last one, you can probably say the entire time is +Stratosphere warming, especially because 10mb never went below a 0 anomaly. It is rising and peaking now though, and on this latest map of Jan 17th: https://ibb.co/W5CDyQG

Average time for effect of this max period is +20 days at this time of the year, so the highest probability of NAO correlation is Feb 5-7, as of right now. 

Here was the 1st wave 10mb warming final analysis: https://ibb.co/s1hYmTY  US temps have looked like this since Jan 5: https://ibb.co/fM3YWKC (I'll probably do a +25 day final analysis when it's available, since that was the estimated time from when 1st wave occurred to effect.)

[Daniel Boone]

10 hours ago, Stormchaserchuck1 said:

The first wave Stratosphere warming occurred Dec 25 - Jan 9th. This was, I would say a 3/10 scale warming. We did get the same kind of effects as the examples above of cold in the US +time, which we are still experiencing now, Jan 20th. -NAO occurred Jan 4-19, so a little sooner than my perfect correlation time. 

Now we are seeing a 2nd wave Stratosphere warming, starting on Jan 13. It's so close to the last one, you can probably say the entire time is +Stratosphere warming, especially because 10mb never went below a 0 anomaly. It is rising and peaking now though, and on this latest map of Jan 17th: https://ibb.co/W5CDyQG

Average time for effect of this max period is +20 days at this time of the year, so the highest probability of NAO correlation is Feb 5-7, as of right now. 

Here was the 1st wave 10mb warming final analysis: https://ibb.co/s1hYmTY  US temps have looked like this since Jan 5: https://ibb.co/fM3YWKC (I'll probably do a +25 day final analysis when it's available, since that was the estimated time from when 1st wave occurred to effect.)

Good work Chuck ! The hyped heat wave may be muted to just a typical January thaw. Blocking will dampen the MJO if it's still in warm phases early February. 

[Stormchaserchuck1]

We've had a moderate Stratosphere warming for the last 7 days.. It even maxed out >2,000, which is pretty strong. 

https://ibb.co/kXmPbht

At this time of the year, 10mb warming correlates to -NAO in +20 days about 2/3 times. That puts it at Feb 2-10.  LR models don't have the NAO negative right now Feb 2-6, so we'll see. (The correlation isn't perfect it could range +5-10 days.)

Some will say that we already had the -NAO effect, but I disagree, on the last day of this 10mb (in this image below), the 500mb NAO is positive, and the historical analysis shows that 10mb usually leads in time, although 500mb and 10mb are kind of lined up right now. 

https://ibb.co/BK0hdy6

[Stx_Thunder]

CPC wrote an interesting and uncertain Week 3 - 4 forecast discussion just this past Friday mentioning about a potential SSW:

https://www.cpc.ncep.noaa.gov/products/predictions/WK34/

I haven’t read enough into (Sudden) Stratospheric Warming phenomenon and particularly data yet, but what are the odds of this happening, going into or in March?

If my memory serves me right over the past few years, I’m sure it’s also had a significant impact on the AO going back into or staying in a Negative phase longer. Which could keep winter from ending too soon over the Central US.

[Stormchaserchuck1]

Mitchnick posted something today that models are projecting a 10mb wind reversal March 5 - Apr 2. There is a 10-15 day lag at this time of year with most probable -AO effects, so that would support a ~March 15-Apr 12 -AO, if it verifies. 

We had this cold 10-day period in January: https://ibb.co/wYR5Jqk  But otherwise, it's been a very warm Winter. If I graded the last two 10mb warmings with average time lag, it would just look warm everywhere.. that doesn't necessarily mean late March is going to be warm though. 

Models haven't been too great on the strength of these Stratosphere warmings so far this Winter, but they have been right from this average time lead, of events happening.  That we have a strong -QBO (2nd lowest January reading on record) and Stronger El Nino also supports +10mb conditions persisting through the cold season.. 

[Stormchaserchuck1]

We had a minor 10mb warming Feb 15-23

The estimated time to impact, March 3-10, looks very warm on current models in the Eastern, US (No +NAO though, it's because of +EPO/-PNA). We may get cold shots in the West during that time. 

This was our 3rd 10mb warming event of the Winter season. 

I believe models were showing a 4th warming event starting after ~March 5. 

[Stx_Thunder]

On 2/18/2024 at 8:24 PM, Stormchaserchuck1 said:

Mitchnick posted something today that models are projecting a 10mb wind reversal March 5 - Apr 2. There is a 10-15 day lag at this time of year with most probable -AO effects, so that would support a ~March 15-Apr 12 -AO, if it verifies. 

We had this cold 10-day period in January: https://ibb.co/wYR5Jqk  But otherwise, it's been a very warm Winter. If I graded the last two 10mb warmings with average time lag, it would just look warm everywhere.. that doesn't necessarily mean late March is going to be warm though. 

Models haven't been too great on the strength of these Stratosphere warmings so far this Winter, but they have been right from this average time lead, of events happening.  That we have a strong -QBO (2nd lowest January reading on record) and Stronger El Nino also supports +10mb conditions persisting through the cold season.. 

 

The more recent CFS runs seem to be hinting at that for late March cold snap in the Central US also. Time will tell in the weeks after March begins. But I’m just not convinced winter is actually done. Even down here in TX. Especially if the -AO phase verifies and has longer duration or more pronounced.

[rainsucks]

8 hours ago, Stx_Thunder said:

 

The most recent CFS runs seem to be latching onto that for late March cold snap in the Central US also. Time will tell in the coming weeks after March begins. But I’m just not convinced winter is actually done. Even down here in TX. Especially if the -AO phase verifies and has longer duration or more pronounced.

I wouldn't bet on it. Besides the CFS being garbage, long range modeling has been way too cold this season, and has also had a tendency to overdo the extent of high-latitude blocking. If anything, I wouldn't be surprised if the overall warm pattern continues to strengthen as the month progresses (especially if we get a high amplitude MJO wave to traverse through phase 6). Our source region is rather iffy, and with a lack of meaningful snow cover throughout the CONUS combined with warm soil temps, things could get really out of hand.