AO Forecast to Plunge

[ORH_wxman]

On yesterday's point that superblocks tend to decay more slowly and renewed blocking tends to redevelop soon after the initial superblock has broken, the latest run of the GFS ensembles is even more adamant about a rebuilding of the blocking. The debate as to whether typical December superblock experience (unprecedented until December 2010 for a La Niña) or typical La Niña blocking experience will define the path forward has increased with the latest run of the GFS ensembles. Whether or not Winter 2010-11 will follow a path more akin to Winter 1970-71 remains to be seen (one warm month in the East vs. the typical two or sometimes three). If the colder 1970-71-type scenario is to play out, a good signal would be a much longer duration of the current blocking regime (now being hinted at by the GFS ensembles).

The Euro ensembles are now hinting at a return to blocking in the Davis Straight region after New Years after what looks like a very brief relaxation before New Years (looking briefer and briefer as we get closer).They weren't nearly as bullish on the idea couple days ago.

[winterymix]

Earlier in this thread, I noted that the only KU-type snowstorm that occurred with a La Niña Region 3.4 anomaly around -1 was the December 1909 bomb. That is incorrect and I regret the error. The January 2000 snowstorm occurred in a month when the Region 3.4 anomaly was -1.86.

The list of KU storms during La Niñas (1950-2009) follows:

Interestingly enough, 6/9 (67%) of KU storms that occurred with a Region 3.4 anomaly of -0.25 or lower commenced when the GWO was either in Phase 4 or 5. 1 of those 9 storms began when the GWO was at Phase 2.

So...

R 3.4 anomaly -1.4

GWO phase 2

My hunch, knowing just enough to be dangerous, is that the (-)AO and (-) NAO are over-riding the La Nina influence by

generating persistant high latitude blocking.

Another hunch is that the Pacific is causing a persistent ridge situated along the Rocky Mountains to be positioned

just a smidgen too far east to give us potential lows that hug the East coast optimally.

What I don't understand is the role of the "Pineapple express", the persistent plume of Pacific moisture. Seems like a seasonal

pattern that has nice ingredients that may not come together in the right way at the right time very often.

[donsutherland1]

The Euro ensembles are now hinting at a return to blocking in the Davis Straight region after New Years after what looks like a very brief relaxation before New Years (looking briefer and briefer as we get closer).They weren't nearly as bullish on the idea couple days ago.

The possible return of blocking is encouraging if one would like to see a cold January. It will be interesting to see if this trend continues. If so, experience with December superblocks might wind up more relevant than that with strong blocks during moderate/strong La Niña events.

[donsutherland1]

So...

R 3.4 anomaly -1.4

GWO phase 2

My hunch, knowing just enough to be dangerous, is that the (-)AO and (-) NAO are over-riding the La Nina influence by

generating persistant high latitude blocking.

Another hunch is that the Pacific is causing a persistent ridge situated along the Rocky Mountains to be positioned

just a smidgen too far east to give us potential lows that hug the East coast optimally.

What I don't understand is the role of the "Pineapple express", the persistent plume of Pacific moisture. Seems like a seasonal

pattern that has nice ingredients that may not come together in the right way at the right time very often.

Certainly, there is potential. I remain concerned about getting the phasing to occur at the right time. Should the timing miss even slightly, the difference in outcomes could be large. If the ridge, as you noted is positioned where it is progged, that will probably reduce the odds of a large snowstorm. For now, I still believe a moderate event is more likely than either a non-event or a blockbuster one. The 0z runs will be interesting to see.

[Snow Wizard]

The Euro ensembles are now hinting at a return to blocking in the Davis Straight region after New Years after what looks like a very brief relaxation before New Years (looking briefer and briefer as we get closer).They weren't nearly as bullish on the idea couple days ago.

So when does the West finally get a turn at some winter weather? I feel like this winter is being stolen from us.

[winterymix]

So when does the West finally get a turn at some winter weather? I feel like this winter is being stolen from us.

You feel this way on 12/21?

[Feb]

So when does the West finally get a turn at some winter weather? I feel like this winter is being stolen from us.

Dial 911

[Snow Wizard]

Dial 911

Funny chit!

It just sucks to be sitting here in an El nino like pattern with January almost upon us.

[Snow Wizard]

You feel this way on 12/21?

To me renewed Davis Strait block in early Jan is like saying kiss January goodbye in the West.

[JamieOber]

Funny chit!

It just sucks to be sitting here in an El nino like pattern with January almost upon us.

I get it. You guys had high hopes. Hopefully it turns for you soon in a way we can all get in on something.

[donsutherland1]

Several quick morning thoughts:

1. The GFS ensembles continue to suggest a redevelopment of blocking, hinting at a 1.5- to 2-standard deviation ridge centered a little south of Greenland by 360 hours.

2. Model wars continue. It is not a slam dunk as to which model suite will prevail.

3. Although general climatology would tend to favor the Euro, moderate/strong La Niña climatology does not. Just a small difference in timing when a phase takes place or if it does would have a substantial impact on the outcome. It is no coincidence that since 1871, there have been only two KU-type storms (December 1909 and January 2000) when the ENSO Region 3.4 anomaly was -1 or below. None of those storms brought 10" or more snow in all of the big cities running from Richmond to Boston (RIC, DCA, PHL, NYC, BOS). Although one cannot rule out what would be an unprecedented event for the 1871-present timeframe were the operational 0z Euro to verify, historical odds are against it.

4. The 12/22 0z ECMWF ensemble mean shifted notably to the east. It's probably close to the compromise position between yesterday's 12z GFS and ECMWF ensemble mean solutions. It might still shift slightly either way, but the latest depiction might offer a fair representation of what lies ahead.

5. It wouldn't surprise me to see some of the disparity between the operational GFS and ECWMF begin to narrow at 12z and perhaps some more prominently during the 12/23 0z run.

[A-L-E-X]

Funny chit!

It just sucks to be sitting here in an El nino like pattern with January almost upon us.

I thought the west was getting plenty of winter weather-- I heard there were reports of widespread 10-15 FEET of snow in the Sierra.

[A-L-E-X]

Thanks, Don, a great synopsis of what we've been discussing!

So as per the definition of KU, there have been only two events that have dumped 10" or more of snow in 3 of the 5 major east coast cities since 1871 with ENSO Reg 3.4 was -1.0 or lower?

How many near misses have we had? I can think of 2/89 right off the bat lol.

[uncle W]

Thanks, Don, a great synopsis of what we've been discussing!

So as per the definition of KU, there have been only two events that have dumped 10" or more of snow in 3 of the 5 major east coast cities since 1871 with ENSO Reg 3.4 was -1.0 or lower?

How many near misses have we had? I can think of 2/89 right off the bat lol.

the winter of 1970-71 had two or three storms in February and March that were mostly rain along the coast but heavy snow inland...That scenario was played out many times from December 1969 to February 1972...Three straight years with storms that just were not cold enough for an all snow event...

[A-L-E-X]

the winter of 1970-71 had two or three storms in February and March that were mostly rain along the coast but heavy snow inland...That scenario was played out many times from December 1969 to February 1972...Three straight years with storms that just were not cold enough for an all snow event...

I guess the nao wasnt neg enough back then, Unc.

Another storm during a strong la nina we've been discussing is March 1956-- but not sure if ENSO 3.4 was still below -1.0 by then.

[donsutherland1]

I guess the nao wasnt neg enough back then, Unc.

Another storm during a strong la nina we've been discussing is March 1956-- but not sure if ENSO 3.4 was still below -1.0 by then.

A-L-E-X,

Although the 1955-56 La Niña had been moderate/strong, it had weakened quite a bit by March. The March 1956 ENSO Region 3.4 Anomaly was -0.78.

[A-L-E-X]

A-L-E-X,

Although the 1955-56 La Niña had been moderate/strong, it had weakened quite a bit by March. The March 1956 ENSO Region 3.4 Anomaly was -0.78.

Thanks much, Don! I suspect the ENSO 3.4 anomaly was around -1 for the 2/89 "near miss"-- but alas, that was a near miss for us-- gave ACY 20" of snow but not much just to the west or north of there.

[donsutherland1]

Thanks much, Don! I suspect the ENSO 3.4 anomaly was around -1 for the 2/89 "near miss"-- but alas, that was a near miss for us-- gave ACY 20" of snow but not much just to the west or north of there.

The February 1989 ENSO 3.4 Anomaly was -1.36 (March was -1.24). Norfolk did really well in February 1989, picking up almost 25" of snow in two events (2/17-19 and 2/23-24).

[A-L-E-X]

The February 1989 ENSO 3.4 Anomaly was -1.36 (March was -1.24). Norfolk did really well in February 1989, picking up almost 25" of snow in two events (2/17-19 and 2/23-24).

Wow, what a winter for them! Does that qualify as a S MA and SNE special-- that is, it hit NC/VA, skipped the megalopolis and then hit SNE, Don? I dont think heavy snow got further up the MA coast than ACY.

[donsutherland1]

Wow, what a winter for them! Does that qualify as a S MA and SNE special-- that is, it hit NC/VA, skipped the megalopolis and then hit SNE, Don? I dont think heavy snow got further up the MA coast than ACY.

I agree. That was essentially the entire winter as far as snowfall was concerned for ORF. ORF did pick up an additional 0.5" on April 11, 1989. Southern New England received below normal snowfall that winter. Aside from the lower Mid-Atlantic to coastal New Jersey, it was a rather forgettable winter.

[A-L-E-X]

I agree. That was essentially the entire winter as far as snowfall was concerned for ORF. ORF did pick up an additional 0.5" on April 11, 1989. Southern New England received below normal snowfall that winter. Aside from the lower Mid-Atlantic to coastal New Jersey, it was a rather forgettable winter.

The funny thing is, we usually think of mod and strong la ninas only being good for snowfall the further north you go. 1988-89 is proof positive against that,

BTW Norfolk getting measurable snowfall on 4/11 is rather amazing! Was that a noreaster also? Im guessing it was cold up here-- but no snow. Dynamically driven, Don?

[donsutherland1]

The funny thing is, we usually think of mod and strong la ninas only being good for snowfall the further north you go. 1988-89 is proof positive against that,

BTW Norfolk getting measurable snowfall on 4/11 is rather amazing! Was that a noreaster also? Im guessing it was cold up here-- but no snow. Dynamically driven, Don?

A few days earlier there had been moderate to heavy precipitation. As I don't have access to the historical maps until I'm home, I can't say whether the light precipitation on 4/11 was associated with backlash or another weak system. What I do know is that there was no precipitation on that day in the northern Mid-Atlantic/southern New England regions and no major storm on the coast.

[Ottawa Blizzard]

Don, I have to say that it's not looking good for us up here. I just watched Bastardi's latest long ranger video and, while I think he is awful at forecasting specific storms, he tends to be good at predicting overall patterns. He explains how the GFS has consistently backed off from its call for a cold start to the new year and how this is indicative of the pattern change coming. The 6z GFS shows a blowtorch developing at a time when it was originally calling for a cold surge. Bastardi went on to explain how the coldest air in the world is being sent over to Asia, the far east and europe. It was a good video, for a change, even though I didn't like the message. It would seem that winter may be toast for us. It will be interesting to see if Ottawa and Montreal record an air temperature of -20 celcius this winter. We didn't in 2001-2002.

This is looking increasingly like 1988-89, although December was colder that year. Interestingly, I recall wondering if a similar setup would take place after that big heatwave in early July. Both July 1988 and July 1999 saw big heatwaves the first week of the month and the following winters were both largely duds up here. Mind you, Europe didn't see the cold that year either, so there are some differences.

[donsutherland1]

Don, I have to say that it's not looking good for us up here. I just watched Bastardi's latest long ranger video and, while I think he is awful at forecasting specific storms, he tends to be good at predicting overall patterns. He explains how the GFS has consistently backed off from its call for a cold start to the new year and how this is indicative of the pattern change coming. The 6z GFS shows a blowtorch developing at a time when it was originally calling for a cold surge. Bastardi went on to explain how the coldest air in the world is being sent over to Asia, the far east and europe. It was a good video, for a change, even though I didn't like the message. It would seem that winter may be toast for us. It will be interesting to see if Ottawa and Montreal record an air temperature of -20 celcius this winter. We didn't in 2001-2002.

This is looking increasingly like 1988-89, although December was colder that year. Interestingly, I recall wondering if a similar setup would take place after that big heatwave in early July. Both July 1988 and July 1999 saw big heatwaves the first week of the month and the following winters were both largely duds up here. Mind you, Europe didn't see the cold that year either, so there are some differences.

Ottawa Blizzard,

Right now, I'm still waiting to see if strong blocking redevelops. The La Niña cases at the beginning of this thread suggest that the AO could go positive during the first week in January, leading to moderation. I continue to lean toward that idea, but it is a lower confidence propositon than with last year's blocking. Superblocking cases would suggest a slower decay and there is enough of a hint on the GFS ensembles for some pause. I do want to see additional data before committing to such an idea. Finally, despite the bleak idea that the coldest air will likely remain on the other side of the globe for some time to come, I am confident that both Montreal and Ottawa will see at least one day on which the temperature falls to -20°C or lower. I don't believe things will be as bad as during the "Non-Winter of 2001-02."

[tacoman25]

Several quick morning thoughts:

1. The GFS ensembles continue to suggest a redevelopment of blocking, hinting at a 1.5- to 2-standard deviation ridge centered a little south of Greenland by 360 hours.

2. Model wars continue. It is not a slam dunk as to which model suite will prevail.

3. Although general climatology would tend to favor the Euro, moderate/strong La Niña climatology does not. Just a small difference in timing when a phase takes place or if it does would have a substantial impact on the outcome. It is no coincidence that since 1871, there have been only two KU-type storms (December 1909 and January 2000) when the ENSO Region 3.4 anomaly was -1 or below. None of those storms brought 10" or more snow in all of the big cities running from Richmond to Boston (RIC, DCA, PHL, NYC, BOS). Although one cannot rule out what would be an unprecedented event for the 1871-present timeframe were the operational 0z Euro to verify, historical odds are against it.

Isn't that extremely rare anyway?

[donsutherland1]

Isn't that extremely rare anyway?

It is, but that's the solution the 0z ECMWF was showing. Odds are still against that solution, but a moderate snowstorm (3"-6"/4"-8" locally higher amounts) is on the table and I believe the 12z GFS' having come into some agreement with the 0z ECMWF ensemble means (something I think is reasonable), which could adjust a little, reaffirms the prospect that at least a moderate event is in play. Hopefully, a KU event would unfold, but I believe that such an event is a lower probability outcome.

[tacoman25]

Don, I have to say that it's not looking good for us up here. I just watched Bastardi's latest long ranger video and, while I think he is awful at forecasting specific storms, he tends to be good at predicting overall patterns. He explains how the GFS has consistently backed off from its call for a cold start to the new year and how this is indicative of the pattern change coming. The 6z GFS shows a blowtorch developing at a time when it was originally calling for a cold surge. Bastardi went on to explain how the coldest air in the world is being sent over to Asia, the far east and europe. It was a good video, for a change, even though I didn't like the message. It would seem that winter may be toast for us. It will be interesting to see if Ottawa and Montreal record an air temperature of -20 celcius this winter. We didn't in 2001-2002.

This is looking increasingly like 1988-89, although December was colder that year. Interestingly, I recall wondering if a similar setup would take place after that big heatwave in early July. Both July 1988 and July 1999 saw big heatwaves the first week of the month and the following winters were both largely duds up here. Mind you, Europe didn't see the cold that year either, so there are some differences.

Perhaps in your neck of the woods, but certainly not for the U.S. overall so far. 1988-89 had a huge +NAO, and the Nov/Dec patterns were much different than what has been seen so far this year.

[uncle W]

last year the blocking was so strong NYC was lucky to pick up what it did...This year the blocking is stronger is keeping storms to far south...I was to young to remember 1954-55 or 1955-56's weather pattern...All I remember is a few light snowfalls and the March 56 storms...1954-55 had very little snowfall and a late winter snowfall kept snowfall from being under 10"...1955-56 had under 10" of snow leading into March...Will this year be similar?...One thing we have going for us is during the mid fifties NYC was in an on going drought while today we are in an on going wet period...I don't known if that means anything but it's a different time and our climate has gotten wetter since then...Does it lead to more snowfall, who knows...

[Whacker77]

I know most of the discussions here focus on the east coast, but do any of the previous cases of a moderate/strong la nina and powerful December blocking indicate the potential for a large midwest snowstorm. I see the 12Z GFS is showing a lake cutting storm around the new year, but what about the Indiana/Kentucky/Ohio region? Does anything show up in the analogs?

[donsutherland1]

I know most of the discussions here focus on the east coast, but do any of the previous cases of a moderate/strong la nina and powerful December blocking indicate the potential for a large midwest snowstorm. I see the 12Z GFS is showing a lake cutting storm around the new year, but what about the Indiana/Kentucky/Ohio region? Does anything show up in the analogs?

As the pattern transitions, the opportunity for cutters will increase. I'll have to look further into some of the cases for more info. The 1950-51 La Niña saw a historic late January snowfall across Tennessee. March 1999 had a big Ohio Valley/western PA snowstorm.