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Pattern December to Remember

BIG FROSTY said:
It's JUST right after this time frame we turn it around... Remember! lol. But that is a ugly looking map, A lot of cold to the NW that should push, slosh, or jump to the SE in time.
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That modeled cold late in the 6Z GFS run is the coldest on the planet then and is hinted at by all of the ensemble means for around that time. At the very least, our primary source region of NW Canada is then frigid with sub -40F in spots. Here’s a global perspective and it is then moving SE031C6517-2D26-426B-8A1C-382EECC333AA.png:
 
GaWx said:
That modeled cold late in the 6Z GFS run is the coldest on the planet then and is hinted at by all of the ensemble means for around that time. At the very least, our primary source region of NW Canada is then frigid with sub -40F in spots. Here’s a global perspective and it is then moving SEView attachment 96887:
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Again. That’s 6z run way out fantasy …
 
tennessee storm said:
Again. That’s 6z run way out fantasy …
Click to expand...

Indeed. I’m weenieing out no doubt. But this is fantasizing supported by the last few ensemble means fwiw:

6Z GEFS 384 has coldest on planet in W Canada and it is large, too:

554FE6D3-A2DF-4773-9B1B-9D1D358075EF.png

Even the 0Z EPS has it sticking out like a frost bitten thumb at its end, 30 hours earlier:

319EC402-94BC-48F2-AC63-67AC85F68237.png

It is all about the primary source region for our coldest airmasses getting frigid.
 
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NorthDFWwx said:
View attachment 96893
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Extreme warmth sometimes precedes extreme cold. I love to follow extremes on both sides even though I strongly prefer the cold. This month has a chance to be one of the warmest Decembers on record. Will be fun to follow. This would also set up the US for the chance for one of the coldest shifts on record from one month to the next. This could potentially set us up for a near normal winter in which the mean hides the reality of ridiculous extremes on both ends.
 
NickyBGuarantee said:
Going to be some big time CADS in our future if we have this level of cold to play with View attachment 96898
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This 0Z CFS is actually a much warmer run for the US than the 18Z, which is what I posted last night. Looking forward to see what the 6Z shows as they jump like crazy from one run to the next. Yes, I’m an extreme weenie this morning. It must have been from my bran flakes.
 
GaWx said:
Extreme warmth sometimes precedes extreme cold. I love to follow extremes on both sides even though I strongly prefer the cold. This month has a chance to be one of the warmest Decembers on record. Will be fun to follow. This would also set up the US for the chance for one of the coldest shifts on record from one month to the next. This could potentially set us up for a near normal winter in which the mean hides the reality of ridiculous extremes on both ends.
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As long as it happens the same way November 2021 did, then whatever.

I actually enjoy having power and heat at my place.
 
BIG FROSTY said:
Here's just a little of Joe D'Aleo post from Saturday.

QBO easterly argues for cold periods. Key levels are 30-45mb.

Screen_Shot_2021_12_04_at_12_26_11_PM.png


Screen_Shot_2021_12_04_at_12_32_39_PM.png


We will see this 'boot' of cold this winter. Many analogs had the cold early, others later when the stratosphere warms.

Screen_Shot_2021_12_04_at_12_31_53_PM.png




Then we could see major snow events that make the list. The October bomb could be a model then. The fall storms are often 'tells'.


So don't fret and don't whine just get your cold forecast where I get mine! And I'll be back on Christmas Day!
Click to expand...
This says that fall storms are often tells, well I hate to break it to ya, but there was a very definite and noticeable lack of fall storms.
 
smast16 said:
This says that fall storms are often tells, well I hate to break it to ya, but there was a very definite and noticeable lack of fall storms.
Click to expand...

There was a very strong slow moving fall storm in early November that gave the Gulf coast, S GA, coastal SE and N FL very heavy rain and gusty winds. I experienced it.
 
NickyBGuarantee said:
What’s funny is the models are pointing at this death ridge eventually retrograding up towards Greenland and eventually our Greenland block shows up in force.. probably won’t be until the last week of December or so
Click to expand...

That's not how this works. A blocking ridge (or trough) that moves from west to east is definitely not "retrograding" because it's in the same direction as the background flow (which is also west to east), that would be actually be a "prograde" motion. What's far more likely happen to develop a -NAO from +NAO is the blocking high over the Barents Sea & Scandinavia would retrograde westward w/ time if the N Atlantic storm track is sufficiently excited by a slow moving, West Pacific MJO event that migrates into the western hemisphere.

See for example:

https://journals.ametsoc.org/view/journals/atsc/69/8/jas-d-11-0289.1.xml

On the other hand, for the NAO+ to NAO− transition events during P2, a comparison between Figs. 8b and 9b shows that the transition events coincide with the NAO− (NAO+) anomaly being markedly enhanced (weakened). A comparison between Figs. 8b and 9b also shows for the NAO+ to NAO− transition events that the SBL (Scandinavian Blocking) is enhanced and exhibits a westward-displaced position. The strengthening and westward-displaced position of the SBL (Scandinavian Blocking) within P2 takes place with the intensification of the NAO− anomaly. Thus, the NAO+ to NAO− transition appears to be connected to the excitation of the enhanced SBL (Scandinavian Blocking) pattern. These results suggest that the enhancement of the SBL (Scandinavian Blocking) pattern plays a role for the NAO+ to NAO−transition events. Thus, the NAO+ to NAO− transition event is likely to coincide with an increase in the amplitude and the westward-displaced position of the SBL (Scandinavian Blocking) pattern. As noted by Cassou (2008), a greater frequency of occurrence of the SBL (Scandinavian Blocking) can lead to an NAO+ to SBL (Scandinavian Blocking) to NAO− transition.


From Part II of this study

https://journals.ametsoc.org/view/journals/atsc/69/8/jas-d-11-0290.1.xml?tab_body=fulltext-display

"It is found that the NAO+ to NAO− transition is more likely to occur when the SBL (Scandinavian Blocking) is enhanced, with the route NAO+ to SBL to NAO− taking place."

An analogous result is found for NAO+ to NAO− transition events when the SBL is strong (Fig. 3b). The difference of the composite NAO index between the weak and strong SBL (Scandinavian Blocking) strengths is statistically significant at the 90% confidence level with a Monte Carlo test. This result indicates that an enhanced SBL (Scandinavian Blocking) pattern favors the transition from the NAO+ to the NAO− event.


Prior to the NAO+ event transiting into an NAO− event, the SBL is generally stronger because of the NAO being positive (Luo et al. 2007). It is found from Fig. 4b that during the NAO+ to NAO− transition the SBL strength is positive between lag −10 and lag +12, indicating a tendency to increase before lag 0 and then decrease until lag +4. A rapid reintensification of the SBL pattern is again seen after lag +4, followed by the beginning of its decay at about lag +7, after which it becomes negative at lag +12. Thus, the transition from an NAO+ to an NAO− event is closely related to a change in the SBL (Scandinavian Blocking) strength. Moreover, it is seen that the occurrence of the SBL precedes the formation of an NAO− event during the NAO+ transition (solid line in Fig. 4b). This is because the NAO− event arises from the retrograde displacement of the SBL (Scandinavian Blocking) pattern. Feldstein (2003) found that European blocks retrograde before an NAO− event forms. More recently, Sung et al. (2011) suggested that NAO− events tend to be preceded by a blocking ridge in the vicinity of northern Europe. Cassou (2008) noted that an enhanced SBL and NAO−, associated with the Madden–Julian oscillation (MJO), can be interpreted as being the consequence of the previous NAO+excitation. However, we see here that the reintensification of the SBL (Scandinavian Blocking) pattern is crucial for the NAO+ to NAO− transition


Also see

https://rmets.onlinelibrary.wiley.com/doi/abs/10.1256/qj.02.76?casa_token=qNmP7R8p9AYAAAAA:CsevTy9aIC0waYxRuOU0UFDPHVUhGVsW2V4fg0qZusYT3VV-kIEta7Ztu641gCuJlodkafAX8dFFAcw


https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2010JD015006


https://idp.nature.com/authorize/casa?redirect_uri=https://www.nature.com/articles/nature07286&casa_token=MeTwFkjjovUAAAAA:Fc9BuCbX5G3xULHwII3ZZML9qVRql5ktM90-q9jL5rK9670BKKCBjZ5NVi0eggY259ToVAHzZk_tLi_6
 
Webberweather53 said:
That's not how this works. A blocking ridge (or trough) that moves from west to east is definitely not "retrograding" because it's in the same direction as the background flow (which is also west to east), that would be actually be a "prograde" motion. What's far more likely happen to develop a -NAO from +NAO is the blocking high over the Barents Sea & Scandinavia would retrograde westward w/ time if the N Atlantic storm track is sufficiently excited by a slow moving, West Pacific MJO event that migrates into the western hemisphere.

See for example:

https://journals.ametsoc.org/view/journals/atsc/69/8/jas-d-11-0289.1.xml

On the other hand, for the NAO+ to NAO− transition events during P2, a comparison between Figs. 8b and 9b shows that the transition events coincide with the NAO− (NAO+) anomaly being markedly enhanced (weakened). A comparison between Figs. 8b and 9b also shows for the NAO+ to NAO− transition events that the SBL (Scandinavian Blocking) is enhanced and exhibits a westward-displaced position. The strengthening and westward-displaced position of the SBL (Scandinavian Blocking) within P2 takes place with the intensification of the NAO− anomaly. Thus, the NAO+ to NAO− transition appears to be connected to the excitation of the enhanced SBL (Scandinavian Blocking) pattern. These results suggest that the enhancement of the SBL (Scandinavian Blocking) pattern plays a role for the NAO+ to NAO−transition events. Thus, the NAO+ to NAO− transition event is likely to coincide with an increase in the amplitude and the westward-displaced position of the SBL (Scandinavian Blocking) pattern. As noted by Cassou (2008), a greater frequency of occurrence of the SBL (Scandinavian Blocking) can lead to an NAO+ to SBL (Scandinavian Blocking) to NAO− transition.


From Part II of this study

https://journals.ametsoc.org/view/journals/atsc/69/8/jas-d-11-0290.1.xml?tab_body=fulltext-display

"It is found that the NAO+ to NAO− transition is more likely to occur when the SBL (Scandinavian Blocking) is enhanced, with the route NAO+ to SBL to NAO− taking place."

An analogous result is found for NAO+ to NAO− transition events when the SBL is strong (Fig. 3b). The difference of the composite NAO index between the weak and strong SBL (Scandinavian Blocking) strengths is statistically significant at the 90% confidence level with a Monte Carlo test. This result indicates that an enhanced SBL (Scandinavian Blocking) pattern favors the transition from the NAO+ to the NAO− event.


Prior to the NAO+ event transiting into an NAO− event, the SBL is generally stronger because of the NAO being positive (Luo et al. 2007). It is found from Fig. 4b that during the NAO+ to NAO− transition the SBL strength is positive between lag −10 and lag +12, indicating a tendency to increase before lag 0 and then decrease until lag +4. A rapid reintensification of the SBL pattern is again seen after lag +4, followed by the beginning of its decay at about lag +7, after which it becomes negative at lag +12. Thus, the transition from an NAO+ to an NAO− event is closely related to a change in the SBL (Scandinavian Blocking) strength. Moreover, it is seen that the occurrence of the SBL precedes the formation of an NAO− event during the NAO+ transition (solid line in Fig. 4b). This is because the NAO− event arises from the retrograde displacement of the SBL (Scandinavian Blocking) pattern. Feldstein (2003) found that European blocks retrograde before an NAO− event forms. More recently, Sung et al. (2011) suggested that NAO− events tend to be preceded by a blocking ridge in the vicinity of northern Europe. Cassou (2008) noted that an enhanced SBL and NAO−, associated with the Madden–Julian oscillation (MJO), can be interpreted as being the consequence of the previous NAO+excitation. However, we see here that the reintensification of the SBL (Scandinavian Blocking) pattern is crucial for the NAO+ to NAO− transition


Also see

https://rmets.onlinelibrary.wiley.com/doi/abs/10.1256/qj.02.76?casa_token=qNmP7R8p9AYAAAAA:CsevTy9aIC0waYxRuOU0UFDPHVUhGVsW2V4fg0qZusYT3VV-kIEta7Ztu641gCuJlodkafAX8dFFAcw


https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2010JD015006


https://idp.nature.com/authorize/casa?redirect_uri=https://www.nature.com/articles/nature07286&casa_token=MeTwFkjjovUAAAAA:Fc9BuCbX5G3xULHwII3ZZML9qVRql5ktM90-q9jL5rK9670BKKCBjZ5NVi0eggY259ToVAHzZk_tLi_6
Click to expand...

And the master continues to school to grasshopper...
 
Webberweather53 said:
That's not how this works. A blocking ridge (or trough) that moves from west to east is definitely not "retrograding" because it's in the same direction as the background flow (which is also west to east), that would be actually be a "prograde" motion. What's far more likely happen to develop a -NAO from +NAO is the blocking high over the Barents Sea & Scandinavia would retrograde westward w/ time if the N Atlantic storm track is sufficiently excited by a slow moving, West Pacific MJO event that migrates into the western hemisphere.

See for example:

https://journals.ametsoc.org/view/journals/atsc/69/8/jas-d-11-0289.1.xml

On the other hand, for the NAO+ to NAO− transition events during P2, a comparison between Figs. 8b and 9b shows that the transition events coincide with the NAO− (NAO+) anomaly being markedly enhanced (weakened). A comparison between Figs. 8b and 9b also shows for the NAO+ to NAO− transition events that the SBL (Scandinavian Blocking) is enhanced and exhibits a westward-displaced position. The strengthening and westward-displaced position of the SBL (Scandinavian Blocking) within P2 takes place with the intensification of the NAO− anomaly. Thus, the NAO+ to NAO− transition appears to be connected to the excitation of the enhanced SBL (Scandinavian Blocking) pattern. These results suggest that the enhancement of the SBL (Scandinavian Blocking) pattern plays a role for the NAO+ to NAO−transition events. Thus, the NAO+ to NAO− transition event is likely to coincide with an increase in the amplitude and the westward-displaced position of the SBL (Scandinavian Blocking) pattern. As noted by Cassou (2008), a greater frequency of occurrence of the SBL (Scandinavian Blocking) can lead to an NAO+ to SBL (Scandinavian Blocking) to NAO− transition.


From Part II of this study

https://journals.ametsoc.org/view/journals/atsc/69/8/jas-d-11-0290.1.xml?tab_body=fulltext-display

"It is found that the NAO+ to NAO− transition is more likely to occur when the SBL (Scandinavian Blocking) is enhanced, with the route NAO+ to SBL to NAO− taking place."

An analogous result is found for NAO+ to NAO− transition events when the SBL is strong (Fig. 3b). The difference of the composite NAO index between the weak and strong SBL (Scandinavian Blocking) strengths is statistically significant at the 90% confidence level with a Monte Carlo test. This result indicates that an enhanced SBL (Scandinavian Blocking) pattern favors the transition from the NAO+ to the NAO− event.


Prior to the NAO+ event transiting into an NAO− event, the SBL is generally stronger because of the NAO being positive (Luo et al. 2007). It is found from Fig. 4b that during the NAO+ to NAO− transition the SBL strength is positive between lag −10 and lag +12, indicating a tendency to increase before lag 0 and then decrease until lag +4. A rapid reintensification of the SBL pattern is again seen after lag +4, followed by the beginning of its decay at about lag +7, after which it becomes negative at lag +12. Thus, the transition from an NAO+ to an NAO− event is closely related to a change in the SBL (Scandinavian Blocking) strength. Moreover, it is seen that the occurrence of the SBL precedes the formation of an NAO− event during the NAO+ transition (solid line in Fig. 4b). This is because the NAO− event arises from the retrograde displacement of the SBL (Scandinavian Blocking) pattern. Feldstein (2003) found that European blocks retrograde before an NAO− event forms. More recently, Sung et al. (2011) suggested that NAO− events tend to be preceded by a blocking ridge in the vicinity of northern Europe. Cassou (2008) noted that an enhanced SBL and NAO−, associated with the Madden–Julian oscillation (MJO), can be interpreted as being the consequence of the previous NAO+excitation. However, we see here that the reintensification of the SBL (Scandinavian Blocking) pattern is crucial for the NAO+ to NAO− transition


Also see

https://rmets.onlinelibrary.wiley.com/doi/abs/10.1256/qj.02.76?casa_token=qNmP7R8p9AYAAAAA:CsevTy9aIC0waYxRuOU0UFDPHVUhGVsW2V4fg0qZusYT3VV-kIEta7Ztu641gCuJlodkafAX8dFFAcw


https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2010JD015006


https://idp.nature.com/authorize/casa?redirect_uri=https://www.nature.com/articles/nature07286&casa_token=MeTwFkjjovUAAAAA:Fc9BuCbX5G3xULHwII3ZZML9qVRql5ktM90-q9jL5rK9670BKKCBjZ5NVi0eggY259ToVAHzZk_tLi_6
Click to expand...

Look no further for real time proof of this than last month, when a blocking high developed over Scandinavia and the Ural Mountains, which when coinciding w/ favorable tropical forcing caused the upstream waves to slow down, break, and divert the N Atlantic storm track south of the blocking high. Coupled w/ tendency for high-latitude, large-scale, & strong Rossby Waves to retrograde westward (via beta advection), eventually this led to -NAO.





Then we got this a few weeks later.
1637080079271.png
 
To sun up what Webber said into my own words, it’s gonna be a top down approach with regards to the thermals. Gonna blast the heat then blast the cold. No step down process or sloshing but rather a top down approach that will be delayed but not denied. It’s yet to be determined how much of winter will be deleted but imo we could be waiting till January 15th at minimum for even a chance of significant winter weather east of the mtns.
 
Goal posts could use some researching. January 15th, February 5th, February 20th and March 10th. Would be nice to see what science and climo can help us pinpoint when to punt and forecast advance winter weather dates for the public. Instead of cramming everything into a seasonal broad forecast I believe there is room to focus the communication on if anyone cares to listen.
 
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