Mid to Long Range Discussion ~ 2023

[olafminesaw]

13 hours ago, StantonParkHoya said:

Anyone that wants snow after March 1 is a sicko

There's a lot of us

[Jmoon]

13 hours ago, StantonParkHoya said:

Anyone that wants snow after March 1 is a sicko

I'll take it anytime anyway I can get it. No matter what month day or time. We hardly get any in the best winters. March is fine by me. Anything to hold off spring and the heat and humidity around the corner. We have had spring around here in our so called winter this year. I'll take a March miracle.

[eyewall]

I believe I saw this is the first time RDU will be blanked since 2005-06.

[PackGrad05]

48 minutes ago, eyewall said:

I believe I saw this is the first time RDU will be blanked since 2005-06.

I thought RDU already accorded a trace, which counts.

[K4CF]

This was posted earlier in the TN valley forum...

[chris624wx]

12z GFS is a decent-ish hit for many next weekend. Probably gone by the 18z run though haha 

[NorthHillsWx]

56 minutes ago, PackGrad05 said:

I thought RDU already accorded a trace, which counts.

Doesn’t count as measurable snowfall you need at least 0.01”. God our bar is low and it’s still a challenge to reach it

[NorthHillsWx]

9 minutes ago, chris624wx said:

12z GFS is a decent-ish hit for many next weekend. Probably gone by the 18z run though haha 

Yes, cold chasing moisture behind a rapidly departing offshore LP on the 10-day GFS, what could possibly go wrong?

[NorthHillsWx]

Wait I take back what I said. The 12z GFS is definitely 100% right. Look at the kuchera map from the GFS, it literally puts Raleigh and Raleigh alone in a snow hole 

[Upstate Tiger]

Does next weekend have legs???....Probably more like a toenail but both GFS and Euro show something to watch at least.

[GaWx]

 1. The string of GFS runs with what appears to be a major SSW/reversal of 60N winds at 10 mb from W to E is now at 8 as of today's 12Z. As opposed to being out of touch, the GFS appears to be leading the GEFS/GEPS as they're continuing to play catch up with the GFS. See section 2, below.

 Also, very importantly, the modeled SSW is moving up in time, which means an earlier onset of potential impacts in the SE than thought earlier. More on this timing in section 3.

 
 2. The GFS leading the way is evident when comparing the two images below. Going below the 0 line on the "Zonal Wind Mean" map (top map of each image) is what's needed for a "major" SSW. As of the top image from 3 days ago (1/31), the GFS was already nearly forecasting a major with it down to +1 m/s on 2/15. Note that it was an outlier with the GEFS/GEPS way up in the +15 to +20 range. Now, look at the 2nd image, which is from today. The GFS is firmly forecasting a major with a low of -10 (2/16). And look how far the GEFS/GEPS have dropped: to close to 0!  

 So, even the GEFS/GEPS are bordering on a major. Based on these trends, the GEFS/GEPS appear to be heading to showing a major.

 

 3. Now I'll address the earlier timing:

 On the older map the GFS winds don't get to its low of +1 til 2/15. In contrast, today's map has the GFS already to a major on 2/13 due to a steeper drop and lower starting point. That's 2+ days earlier! The old GFS was still up at +15 on 2/13. 

 Regarding temperatures (bottom map of each image), the old GFS showed warming not starting til 2/13 (from 221 K). In contrast, the new GFS' warming starts on 2/9 (4 days earlier) and from a warmer starting point of 224. As of 2/13, the new GFS was already up to 230 or 9 warmer than the old GFS.

 Also, the old GFS was still warming as of 2/16 (reaching 230 three days later than the new GFS). The new GFS has already peaked on 2/15 (at 237), when the old GFS was still down at 225.

 

4. Summary:

 - Chances for a major SSW continue to increase as the GFS leads the way. As of today's 12Z run, 8 in a row have had a major SSW.

 - The timing of the forecasted SSW has moved ~2-3 days earlier vs what models were showing just three days ago. This means an increased chance vs what was earlier thought for cooling effects on the SE, should they occur, to start during the last week of Feb as opposed to the first week of March.

 

Images of strat winds/temps: GFS in orange

Older (based on 1/31 runs):

 

New (based on 2/3 runs):

[eyewall]

On 2/3/2023 at 10:47 AM, PackGrad05 said:

I thought RDU already accorded a trace, which counts.

I am referring to measurable.

[NorthHillsWx]

Beautiful week coming up. Pretty excited for sunshine and 60’s!

[JoshM]

I think I'm going with the Canadian groundhogs winter prediction

 

https://www.usatoday.com/story/news/world/2023/02/02/fred-la-marmotte-dead-groundhog-day/11171427002/

[GaWx]

Wow regarding the 0Z GFS strat forecast!! Check it out (loop this for the entire run, which gets very interesting from 2/10 to the end):

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nhem&pkg=Tz10&runtime=2023020500&fh=-12

 

 What is most needed to get out of the neverending ugly pattern is major chaos. One potential source of major chaos is the strat. The chance of strong AO/NAO blocking goes up significantly 10+ days after a major weakening of the SPV. This run's strat becomes about as chaotic as one would want. If something close to this were to verify, there'd be no telling what would happen in the SE starting as early as the last week of Feb, especially considering MJO forecasts.

[JoshM]

1 hour ago, GaWx said:

Wow regarding the 0Z GFS strat forecast!! Check it out (loop this for the entire run, which gets very interesting from 2/10 to the end):

https://www.tropicaltidbits.com/analysis/models/?model=gfs&region=nhem&pkg=Tz10&runtime=2023020500&fh=-12

 

 What is most needed to get out of the neverending ugly pattern is major chaos. One potential source of major chaos is the strat. The chance of strong AO/NAO blocking goes up significantly 10+ days after a major weakening of the SPV. This run's strat becomes about as chaotic as one would want. If something close to this were to verify, there'd be no telling what would happen in the SE starting as early as the last week of Feb, especially considering MJO forecasts.

Thanks for the information, as usual.  If the SSW doesn't work out, our last option is getting the weather control machine from the Sims 4

[GaWx]

 SSWs have had varying effects on the SE. What may very well turn out to be different from the prior one is that the upcoming strat warming is looking increasingly likely to be "major" (see 1st image, in which the GFS is showing quite the major event with 60N 10 mb winds dropping to well below 0 m/s). Before anyone says anything about the unreliability of the GFS vs ensemble means, it has been leading the way, which is quite evident when looking back to 1/31 runs at the Stratobserve website at the following:

https://stratobserve.com/ens_ts_diags

 

  Another thing to keep in mind is the Scandinavian-Greenland (S-G) dipole, which looks to me like it is forecasted to exceed 40 mb per the 2nd image below. Learn about the S-G dipole here:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JD030940

"The correlation field indicates that ensemble members with lower MSLP over eastern Greenland and higher MSLP over Scandinavia forecast weaker U1060."

 "Of the 23 SSWs (Karpechko et al., 2017), we find eight (35%) followed a similar evolution to 2018 and were preceded by an S-G dipole exceeding 40 hPa within 15 days of the start date of the SSW. Given the total of 345 days preceding the 23 events (and assuming independence), this is 2.3 times larger than the climatological likelihood (since 40 hPa is approximately the 99th percentile, it would be expected that it was exceeded on 3-4 days)."

 "We therefore suggest the S-G dipole should be monitored operationally as a precursor to SPV weakening."

"When 2018 is included, 78% of the major SSWs preceded by an amplified S-G dipole were downward propagating (Karpechko et al., 2017), with only March 1981 and February 2008 otherwise. This is larger than the observed ratio of 57% (although the sample is too small to draw robust conclusions) but is in agreement with Birner and Albers (2017), who note larger tropospheric impacts following SSWs preceded by enhanced tropospheric wave activity."

 Per table 1 from this article, the following 8 SSWs had a 40+ mb S-G dipole peak during the 15 days prior:

Feb of 1979, Feb of 1980, March of 1981, Feb of 1984, Jan of 1985, Jan of 1987, Jan of 2006, and Feb of 2008.

 Also, Feb of 2018, which this article highlighted, had a 40+.

 So, one might want to focus on the tropospheric impacts of the above listed 9 SSWs to get a better idea of how the upcoming SSW may affect the SE US late this month into March+. I say late this month because I believe based on the timing of past cases that any potential cold resulting from this may start as early as the last week of this month.

 

Image 1 showing that today's 0Z GFS is forecasting a major SSW:

 

Image 2 suggesting likelihood of S-G dipole peak of 40+ mb coming tomorrow:

[Coach McGuirk]

I suppose early March is still on the table.

[StantonParkHoya]

52 minutes ago, Coach McGuirk said:

I suppose early March is still on the table.

Mmm, cold rain. Can’t wait! Sickos

[Coach McGuirk]

7 minutes ago, StantonParkHoya said:

Mmm, cold rain. Can’t wait! Sickos

In the 2006-2007 winter, SEVAs, first accumulating snow came in early April.  I got 1 inch in Yorktown, VA.  Williamsburg got 3 inches.  

[GaWx]

 The CFS is terribly unreliable. It typically changes wildly from run to run. Also, it is too cold over snowcover. However, because it an operational that goes out much further (which is one reason it shifts wildly), it like the Euro control is fun to look at for "what if" possibilities.

 The last 3 runs, especially the last 2, go from +AO/+NAO for the next 2+ weeks to a strong -AO/-NAO starting in late Feb. That's interesting because that's what a major SSW would often lead to starting 7-10+ days later. The result in the SE from that is often a colder pattern following soon afterward.

 That's precisely what these CFS runs are showing. Today's 12Z is late Feb-early March of 1960 all over again in the SE with MB temps and 3 winter storms within just one week. ATL doesn't get above low to mid 40s 2/25-3/7. They don't get above 35 F 2/28-3/4. These are very similar to early March of 1960. Also, this would easily be the longest strong cold stretch there and throughout the SE since early January of 2018! This shows that if the right atmospheric ingredients are there, the SE can have a lengthy very cold and wintry period even in early March.

**Edit: I should add that the MJO is looking favorable to allow for cold later this month, a very important ingredient.
  
 Yes, it is likely overdone even if there is a strong -AO/-NAO then. But this does at least give an idea of the type of thing that a major SSW at midmonth can do. 

[KChuck]

Last one to leave please turn out the lights.

[CaryWx]

I usually give it until Feb 20th on the calendar. If there is nothing showing on the 10day once we get to 2/20 I tend to check out because now were hoping for the 2nd week of March or beyond for the LR proggs and well...that's just betting against climo and you're staying in the casino too long.

[GaWx]

 1. The 0Z GFS is likely overdone since it is predicting a near record Feb low 10 mb wind at 60N of -27 m/s on 2/18/23 and is an extreme outlier vs ensemble members. But fwiw you can see it in the top graph of the first image below in orange. More importantly and to the GFS' credit since it has had a major SSW on its last 20 runs often as an outlier, the same image shows that all of the ensemble means have followed the GFS' lead that started five days ago and for the first time now have a major (at -4 m/s on 2/18).

2. The 2nd image shows Arctic strat temperatures this winter to date along with the GFS forecast through Feb 22nd. Looking at the winter through Jan 23rd, which was just prior to the minor SSW of late Jan, you can see the dominance by blue (cold) anomalies.

 The peak cold strat near New Year's was near a record low strat temp as well as anomaly, which equated to a near record strong SPV. That's a key reason this winter has been so warm to date. But then note the late Jan minor SSW. And on the right, you can see the forecasted major SSW, the polar opposite extreme (even though it is likely overdone as already stated). That along with the forecasted MJO is why I feel there's a good chance for a change to a much colder pattern in the E US overall possibly starting as early as during the last week of Feb.

 

Image 1 top graph shows GFS (orange) with near record Feb low 10 mb 60N wind of -27 m/s and also ensemble means having a major SSW for first time:

Image 2 shows how cold it was in the stratosphere through 1/23 (especially near New Year's) along with the strong warming from the minor SSW and the forecasted major SSW:

[GaWx]

 Courtesy of Dr. Simon Lee's Twitter, the 0Z EPS mean is also now forecasting a major SSW and a rather stout one at that with a 60N 10 mb wind low of -10 m/s on 2/19 (see image below). That would be a whopping 33 m/s below the climo mean of +23 for the date. It is currently +30. The run from four days earlier had it dipping down only to +3 (on the same date). So, now all of the major ensemble means have a major. Most importantly, note that over 90% of the 50+ EPS members show a major. Also, note that the bottom 10% of members are in the -25 to -30 range, which is where the 0Z GFS is and would be near a record low for Feb.

------------------------

 0Z 2/6/23 EPS mean prog (thick blue line) of 60N winds at 10 mb showing a major SSW (below the pink line from 2/16 through 2/22) with it dipping all of the way down to -10 m/s on 2/19:

 

 Here's a tweet from Dr. Lee from earlier today:

Edit: To compare, the prior runs available at the website never had anything lower than +5 m/s for the low in advance of the recent minor SSW.

[dsaur]

3 hours ago, GaWx said:

 Courtesy of Dr. Simon Lee's Twitter, the 0Z EPS mean is also now forecasting a major SSW and a rather stout one at that with a 60N 10 mb wind low of -10 m/s on 2/19 (see image below). That would be a whopping 33 m/s below the climo mean of +23 for the date. It is currently +30. The run from four days earlier had it dipping down only to +3 (on the same date). So, now all of the major ensemble means have a major. Most importantly, note that over 90% of the 50+ EPS members show a major. Also, note that the bottom 10% of members are in the -25 to -30 range, which is where the 0Z GFS is and would be near a record low for Feb.

------------------------

 0Z 2/6/23 EPS mean prog (thick blue line) of 60N winds at 10 mb showing a major SSW (below the pink line from 2/16 through 2/22) with it dipping all of the way down to -10 m/s on 2/19:

 As the globe heats up I think we'll see more crazy stuff, like wall to wall heat with a blizzard in the middle of it.  More extremes....multiple 10 inch spring snows, ice storms in Nov, lol. In my old age I'm holding out for the amazingly anomalous as I doubt I'll see winters like the 50's, 60's and 70's again though I can imagine a winter like the early 40's or late 1800's had thrown in just for climo giggles

 Here's a tweet from Dr. Lee from earlier today:

  A

 

 

[GaWx]

 Yesterday (2/6), the S-G dipole (Scandinavian SLP minus NE Greenland SLP) was very strong and likely exceeded 40 mb. The following link is to the article from which I learned about the S-G dipole and its predictive ability for major SSWs within 15 days when it exceeds 40 mb:

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019JD030940
 

 From this:

  "When 2018 is included, 78% of the major SSWs preceded by an amplified S-G dipole were downward propagating (Karpechko et al., 2017), with only March 1981 and February 2008 otherwise. This is larger than the observed ratio of 57% (although the sample is too small to draw robust conclusions) but is in agreement with Birner and Albers (2017), who note larger tropospheric impacts following SSWs preceded by enhanced tropospheric wave activity."

-----------------------
 So, for the SSWs preceded by a 40+ mb S-G dipole that were downward propagating (78% of them), here were the AOs for the week centered on that day, on the week centered on two weeks later, and on the week centered on three weeks later:

* = during La Niña 

- 2/22/1979: -0.3, +0.8, -2.7

- 2/29/1980: -0.5, -1.3, -2.8

* - 2/24/1984: -0.7, -2.5, -3.1

* - 1/1/1985: -2.1, -3.4, -3.5

- 1/23/1987: -1.1, -0.3, -2.8

* - 1/21/2006: -0.1, -1.8, 0.0

* - 2/12/2018: +1.5, -1.9, -3.3

 

- Average of the seven: -0.5, -1.5, -2.6

- This tells me that assuming the upcoming SSW downwardly propagates, look for an AO plunge to most likely start within two weeks and possibly within 10 days of the SSW (likely during last few days of Feb to first few of March). Then look for it to most likely last at least 2 weeks.

- Look for the strongest -AO week to most likely be the week centered on 3 weeks after the SSW. So, in the upcoming case, ~Mar 5-11, although the prior week could also have a strong -AO.

- Note that the only year with a strong week of +AO during the SSW (2018, a La Niña) similar to now was still able to plunge to a strong -AO 2-3 weeks later. Despite the strong +AO initially, the -AO for those two weeks averaged out actually ended up significantly stronger than 4 of the other 6 weeks! Only 1984 (barely) and the historic 1985 had a stronger -AO.

 The 2018 AO plunged fastest starting 13 days after that SSW. 2006 took 10 days to start dropping its fastest while 1987 took 17 days, 1985 took 12 days, 1984 took 10 days, 1980 took 12 days, and 1979 took 15 days. So, range of 10-17 days after SSW date for the AO to accelerate downward. For the four La Niña events, alone, the range was 10-13 days. The four La Niñas propagated a good bit more quickly (average of just 11 days) than the average of the other three (15 days).
 
 So, for the upcoming case assuming it propagates downward, look for the AO to start dropping the most rapidly for a sustained period of time most likely starting ~2/24-2/28 although it may wait til 3/5. If there's no big AO drop by 3/5 and none forecasted, I'd then be thinking it probably won't propagate downward.

[JoshM]

That's gonna be some cold rain

[eyewall]

42 minutes ago, JoshM said:

That's gonna be some cold rain

Just need the ULL a bit farther south.

[WiseWeather]

Just need the ULL a bit farther south.

Shoot down a chinese weather balloon and weird things happen…


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