Would these storms work today?

[psuhoffman]

@WxUSAF @Bob Chill @showmethesnow @C.A.P.E. @usedtobe @Ji @frd or anyone else that wants to interject... 

I wanted to contain this discussion here because we all know it can spin out of control and derail the main thread.  But this is something I hinted at in a post earlier and its been kicking around my head ever since I saw the upcoming pattern shift into a Hudson Bay centered Ridge with a +AO.  I remembered our area actually had quite a few decent snowstorms in that pattern...it was one of the best ways to get snow with a +AO actually... but also that almost all of them were very marginal events that mixed a lot in the cities and they were way more common in the 50s, 60s, 70s and 80s and less so since.  I went back and looked at the snow records I had put together for my mini study...plus looked at some storms that were just under the 5" threshold but still decent snowfalls around the region (some much better just NW of DC/Balt) to see how many also fell into a similar pattern.  

Look at some of these 3"+ snowfalls at DCA  in somewhat similar pattern I found between 1958 and 1992 and how marginal they were... look at the low temps and qpf 

Hi    Low   QPF    Snowfall

36-30    1.13     4.6

37-30       .77     4.1

45-33      .86      6.9

34-31      .92      3.0

37-33      .92     3.4

39-32      .72      3.0

43-33      1.09    5.5

39-31       1.04     6.9

39-32       .67       3.4

33-30       1.63      6.4

38-33        1.03       3.3

These are all not a perfect match but they all featured a somewhat similar central Canada ridge pattern without much AO help.  

Obviously these were all very mixed events.  A lot of them were significantly more snow NW of the cities.  In general they fit a profile of 3-6" mixed events in DC and 6"+ events west of the fall line... but would these events even work today or would they be marginal mixed events NW and just rain in DC?  Or maybe simply just rain everywhere since a couple degree difference in an event so marginal can simply cause the whole system to take a further north track which would potentially shift the whole baroclinic boundary significantly.  

On the other hand we seem to be getting snow more often recently in some patterns that were historically cold but dry looks.  

I am just bringing this up because in my snow study a LOT of snowfalls with this type of marginal central Canada ridging look showed up regularly in the 50s-early 90s...then they became very rare after that.  While in the last 20 years we have had a lot of EPO ridge +AO snowstorms which were extremely rare before that.  

I admit this is all VERY VERY VERY speculative, I have not put any real study into it yet just thinking out loud here based on things I noticed when surveying our snowfall data and patterns.  

Thoughts?  

 

[Scarlet Pimpernel]

Just throwing this out there, too, if I may...

I've also been wondering about something like "Commutageddon" (Jan. 26, 2011).  Now I know that's not in your "historical decades" list, and it's obviously much more recent.  And it was a highly dynamic storm in the mid-levels, which may not correspond to the type you have here.  But as I recall the temperatures were borderline, at or just above freezing when the heavy, wet snow fell.  I'm not familiar with the ones you list, as I wasn't here through that time.  Were they similar in any way to how Commutageddon went?  Maybe the extreme dynamic setup is the only reason Commutageddon worked out for us, as a more recent event?

[frd]

13 minutes ago, psuhoffman said:

I admit this is all VERY VERY VERY speculative, I have not put any real study into it yet just thinking out loud here based on things I noticed when surveying our snowfall data and patterns.  

Thoughts?  

Random thoughts ...... some may hit your question,  others not , will also think more about this tonight. 

Temperature profile of the Atlantic might be one reason, effecting confluence and blocking.....changes have happened over the past couple decades in the Atlantic, maybe even the Gulf Stream. and changes up near Greenland too.  

Changes in the Pacific Ocean current and base state in the last 20 years - with an emphasis on the Western Warm pool .  Favoring warmth phases over cool/cold  - faster Pac jet, more warmth transport, higher moisture content.  

bluewave and others have posted and mentioned there has been some sort of change in normal snowfall distribution during the last 10 years.   more snow in warmer periods. 

Reduction in Sea ice leading to changes in the EPO region .

Slightly rising global temps  

Maybe the current global base state favors more higher impact , higher moisture events, but not as cold as decades ago due to the reason above.

You get more warmer snowfalls, more dynamic snowfalls but less small scale REGIONAL snow events because cold air can't not maintain  or counter  the warmer push.  Might even over lap into the global baroclinic zone and the wash out effect. You need dynamic systems to produce the snowfall anything less or weaker events are rain, unlike decades ago. 

Maybe these effects are more pronounced at lower latitudes as well, meaning our area and the area in your study.  That might be a reason as well. 

Ha ha that is my wag. 

 

 

 

[mattie g]

I don’t think they’d work the same at DCA, but they might in the suburbs, assuming the dynamics assisted in some way. Not so sure they would work well in DC, either.

DCA is really an anomaly nowadays.

[psuhoffman]

6 minutes ago, mattie g said:

I don’t think they’d work the same at DCA, but they might in the suburbs, assuming the dynamics assisted in some way. Not so sure they would work well in DC, either.

DCA is really an anomaly nowadays.

I agree with this...in the last 15 years I have had many marginal events up here that historically I thought it should have been at least "some" snow in DC but instead it was just cold rain or non accumulating rain/snow mix in the urban corridor.  It seems some of the storms that historically were 6-12" up here and 2-4" in DC are still good snows up here but nothing in the cities.  But that is just observational with no real study/data to prove my hypothesis.  Just seems almost every marginal 50/50 type situation breaks warm/no snow for DC lately.  They need a legit very good setup to get snow.  Marginal events don't work anymore.  But this could be recency bias.  

[psuhoffman]

@frd thanks for your thoughts... this could all be totally off...its just something I noticed but have no hard evidence to back it up.  BTW I am most definitely NOT saying this upcoming pattern cannot work... even if there is truth to my observation it just might mean it will be "harder" to work.  And this could be completely my own observational bias and nothing too it.  

There does seem to be a change to the snowfall patterns when I compared how it "used to snow" to how we commonly get snow now though.  It's largely a wash, means are going down but not as fast as they could because some patterns that didnt produce are starting too...and some that used to have not.  Cold patterns have become more snowy and that would fit with enhanced waves from the increased baroclinicity due to an overall warmer thermal profile.  What used to be a cold dry pattern could have more potential now in that regime.  What used to be a warm pattern that could support marginal snow events.. could be skewing less favorable.  In the end that could be a wash...at least to a point.  

[WxUSAF]

It’s indisputably gotten warmer over the last 30 years, with the last 10-15 years really spiking. When a degree or two is important for precip type in winter storms, that matters. Everyone in the area has gotten a few ticks warmer, but the burbs had more cushion since they’re colder to begin with. Add in some extra help from the UHI for the areas inside the beltways and it just makes marginal events into white rain or plain rain. 

Unfortunately, the burbs are following along behind on warming and will also probably see marginal events slip away in the coming decades.

[psuhoffman]

55 minutes ago, WxUSAF said:

It’s indisputably gotten warmer over the last 30 years, with the last 10-15 years really spiking. When a degree or two is important for precip type in winter storms, that matters. Everyone in the area has gotten a few ticks warmer, but the burbs had more cushion since they’re colder to begin with. Add in some extra help from the UHI for the areas inside the beltways and it just makes marginal events into white rain or plain rain. 

Unfortunately, the burbs are following along behind on warming and will also probably see marginal events slip away in the coming decades.

all true...but have the suburbs already lost the storms from 30-50 years ago where they got 6" of 33 degree slop and the city was all rain then?  

[WxUSAF]

Dunno. I think bwi and iad would be a decent first check on that, although the uhi at bwi and iad has clearly gotten worse over time as well. 

[Inverted_Trough]

DCA also used to know how to measure snow back then.  Nowadays with marginal temps they always report a "Trace".  See the last storm.  

[psuhoffman]

6 minutes ago, Inverted_Trough said:

DCA also used to know how to measure snow back then.  Nowadays with marginal temps they always report a "Trace".  See the last storm.  

Years ago there was a report they actually were measuring at a location surrounded by concrete where nothing would accumulate basically anytime there was no road accumulations. But I can’t verify it and I think I remember there was a dispute of that report. That would explain a lot though. 

[cbmclean]

I know the question below isn't strictly speaking on topic, but I've been looking to find a place to have a quite, reasonable discussion of climate change potential impacts on winter.  Maybe this is the place.

I am really curious to hear what you guys think about the current drought in North Atlantic blocking.  I know that BobChill has mentioned repeatedly that it has gone through decadal trends for the whole period that we have been measuring it, but my lord it seems to be almost impossible to get a -NAO for more than five minutes.  Just normal variation or ominous sign of things to come?  Or simply not enough data to tell?

[PrinceFrederickWx]

41 minutes ago, Inverted_Trough said:

DCA also used to know how to measure snow back then.  Nowadays with marginal temps they always report a "Trace".  See the last storm.  

I work in PG county and it was at least a half-inch of snow cover there the next day- and this is south and east of DCA. 

 

6 minutes ago, cbmclean said:

I know the question below isn't strictly speaking on topic, but I've been looking to find a place to have a quite, reasonable discussion of climate change potential impacts on winter.  Maybe this is the place.

I am really curious to hear what you guys think about the current drought in North Atlantic blocking.  I know that BobChill has mentioned repeatedly that it has gone through decadal trends for the whole period that we have been measuring it, but my lord it seems to be almost impossible to get a -NAO for more than five minutes.  Just normal variation or ominous sign of things to come?  Or simply not enough data to tell?

I’d be curious about this too- are there any studies linking climate change to a lack of -NAO in winter?

[frd]

 

Maybe the warming base state is reducing the smaller events. The end , as Simon mentioned , is truly remarkable.  

 

 

[psuhoffman]

On 1/18/2020 at 11:51 AM, frd said:

 

Maybe the warming base state is reducing the smaller events. The end , as Simon mentioned , is truly remarkable.  

 

 

If you go back over the last 5 days or so...and look at all the different analogs spit out by NCEP and CMC for the day 8 and day 11 looks... there actually were a handful of analogs that "worked" for some snow around here...but they were almost all from years in the 1950s-1980s.  The h5 analogs that were more recent from the 90s on were all from big rainstorms.  Just an observation... On top of that, as bluewave has pointed out...its becoming increasingly harder to get a legitimate "cold base state" to winter in the mid atlantic.  Basically if we have an uber -EPO or -NAO the majority of winter we can get a cold winter...the rest of the time we are above normal.  It's very hard to get a prolonged simply "normal" temperature regime unless its a temporary period of transition.  Pretty much we need a very anomalous ridge in either the EPO or NAO domain to dominate...or else we are well above normal for winter.   

[frd]

2 hours ago, psuhoffman said:

Pretty much we need a very anomalous ridge in either the EPO or NAO domain to dominate...or else we are well above normal for winter.   

 

Very sad indeed. We had the record breaking - NAO in the late Spring and summer.  Getting blocking in the wrong seasons now. 

Also goes to show you using any kind of SAI or NA , even NH snow cover is totally useless. 

All that crap about the Siberian High in the Fall and other Judah stuff is useless in this new warmer climate. 

I take Tom's work over Judah's any day. His understanding seems o be more relevant and useful to what we are facing these days globally from a weather perspective.  

I never want to hear about  snow advance or record breaking snow cover again. Two years in a row and zero relationship to the winter. Even record NA snow cover is a non factor as well. Same as last year.  

 

 

 

 

 

[psuhoffman]

43 minutes ago, frd said:

 

Very sad indeed. We had the record breaking - NAO in the late Spring and summer.  Getting blocking in the wrong seasons now. 

Also goes to show you using kind of SAI or NA , even NH snow cover is totally useless. 

All that crap about the Siberian High in the Fall and other Judah stuff is useless in this new warmer climate. 

I take Tom's work over Judah's any day. His understanding seems o be more relevant and useful to what we are facing these days globally from a weather perspective.  

I never want to hear about  snow advance or record breaking snow cover again. Two years in a row and zero relationship to the winter. Even record NA snow cover is a non factor as well. Same as last year.  

 

Notice I never even factor the snowcover/ice stuff into my thinking in the fall lately.  Its useless.  IMO it shows backwards correlation because it was useful as a predictor during the colder regimes.  But with ice and snowcover reaching record low totals almost every fall now...we will naturally see a significant "increase" once the cold season sets in at high latitudes.  So that is less useful as a predictor of what the pattern is actually doing.  I don't need a ton of statistics to tell me that, its common sense. 

Tom nailed the PV.  Absolutely 100%.  And his equation shows predictability way above climo which is rare for long range seasonal forecasting.  I have just begun to dip my feet into some of the factors he incorporates.  I am not even close to where I want to be yet...but I will get there.  I will do a lot more reading and research in the dead time next summer.  I think there is definitely something to it.  

From my limited understanding of the correlation between AAM global phases and the pattern... what sticks out so far, incorporating some other resent studies and observations...is that there seems to be less coupling between the older typical indicators like enso, north pac sst, atlantic sst...and the MJO and other tropical pattern drivers.  This decoupling will result in non typical results if we just look at things like the enso state because the forcing they were associated that actually impacted the pattern is no longer the same.  

Now I don't think this is true of a strong enso event.  We have seen canonical nino results from years like 2003, 2010, and 2016.  But in years with a weaker enso signal...its more likely for other factors like the AAM to not be in alignment with historical expectations.  The warmer base state and changes in the IO and western PAC SST are causing other factors to be more dominant than enso when its a weak signal imo.  

One troubling thing... some of those changes are biasing those other factors towards what we would typically associate with a nina atmospheric response in the Pacific.  If that is the case, and it seems to be some truth to that, we will lose "enso neutral or weak warm" years as a good probability for snow.  In the past enso neutral or a weak nino was a decent chance for a cold/snowy winter.  Not as good as a moderate nino of course...but still a way better odds for a snowy year than a nina.  But lately those years are skewing warm also.  

Obviously we will need more time to confirm this...and reasearch...but just thinking out loud... if this is all true what our new climo would be would likely be even more extremes.  The warming does seem to be increasing our chances of hitting BIG storms when the pattern is conducive...but we are spending less and less time in a conducive pattern.  So the result of that could be bigger big years and worse years when its not one of those.  In the end our "avg" might not change much but how we get there will become even more skewed between crazy snowy years and crap years in between.  

[frd]

13 minutes ago, psuhoffman said:

he warming does seem to be increasing our chances of hitting BIG storms when the pattern is conducive...but we are spending less and less time in a conducive pattern.  So the result of that could be bigger big years and worse years when its not one of those.  In the end our "avg" might not change much but how we get there will become even more skewed between crazy snowy years and crap years in between.  

I like that train of thought. 

I can see extreme snowfall when the conducive patterns return.  Some years huge, well above climo and several below,  but in the end averaging to climo. 

Tom's work is enlightening. The thing that sticks in my mind about his work is the focus he has on the eventual hand off to players that guide a favorable pattern, or reasoning they will not. He and others in his clan of strat enthusiasts focus on energy transport, GLAAM, AAM, the TPV, etc,  unusual methods to provide a clue to the coming season.  Learned a lot reading his work about coupling, the TPV, energy transport, etc. 

It should have worked last year, and this year he basically went with the disconnect and he is so far doing very well.  He call about  NAO is right on target. For him to really do a complete seasonal call and get icing on the cake would be for the pattern to turn snowy and cold in his window which if memory serves me correctly is  after Feb 20th to early March. @Isotherm please correct me if I am mistaken regarding my previous statement.

If anything the new warmer base state has made the study of meteorology even more difficult , and even more so in  the long range field. 

 

[Isotherm]

5 hours ago, frd said:

 

Very sad indeed. We had the record breaking - NAO in the late Spring and summer.  Getting blocking in the wrong seasons now. 

Also goes to show you using any kind of SAI or NA , even NH snow cover is totally useless. 

All that crap about the Siberian High in the Fall and other Judah stuff is useless in this new warmer climate. 

I take Tom's work over Judah's any day. His understanding seems o be more relevant and useful to what we are facing these days globally from a weather perspective.  

I never want to hear about  snow advance or record breaking snow cover again. Two years in a row and zero relationship to the winter. Even record NA snow cover is a non factor as well. Same as last year.  

 

 

 

 

 

 

4 hours ago, psuhoffman said:

Notice I never even factor the snowcover/ice stuff into my thinking in the fall lately.  Its useless.  IMO it shows backwards correlation because it was useful as a predictor during the colder regimes.  But with ice and snowcover reaching record low totals almost every fall now...we will naturally see a significant "increase" once the cold season sets in at high latitudes.  So that is less useful as a predictor of what the pattern is actually doing.  I don't need a ton of statistics to tell me that, its common sense. 

Tom nailed the PV.  Absolutely 100%.  And his equation shows predictability way above climo which is rare for long range seasonal forecasting.  I have just begun to dip my feet into some of the factors he incorporates.  I am not even close to where I want to be yet...but I will get there.  I will do a lot more reading and research in the dead time next summer.  I think there is definitely something to it.  

From my limited understanding of the correlation between AAM global phases and the pattern... what sticks out so far, incorporating some other resent studies and observations...is that there seems to be less coupling between the older typical indicators like enso, north pac sst, atlantic sst...and the MJO and other tropical pattern drivers.  This decoupling will result in non typical results if we just look at things like the enso state because the forcing they were associated that actually impacted the pattern is no longer the same.  

Now I don't think this is true of a strong enso event.  We have seen canonical nino results from years like 2003, 2010, and 2016.  But in years with a weaker enso signal...its more likely for other factors like the AAM to not be in alignment with historical expectations.  The warmer base state and changes in the IO and western PAC SST are causing other factors to be more dominant than enso when its a weak signal imo.  

One troubling thing... some of those changes are biasing those other factors towards what we would typically associate with a nina atmospheric response in the Pacific.  If that is the case, and it seems to be some truth to that, we will lose "enso neutral or weak warm" years as a good probability for snow.  In the past enso neutral or a weak nino was a decent chance for a cold/snowy winter.  Not as good as a moderate nino of course...but still a way better odds for a snowy year than a nina.  But lately those years are skewing warm also.  

Obviously we will need more time to confirm this...and reasearch...but just thinking out loud... if this is all true what our new climo would be would likely be even more extremes.  The warming does seem to be increasing our chances of hitting BIG storms when the pattern is conducive...but we are spending less and less time in a conducive pattern.  So the result of that could be bigger big years and worse years when its not one of those.  In the end our "avg" might not change much but how we get there will become even more skewed between crazy snowy years and crap years in between.  

 

4 hours ago, frd said:

I like that train of thought. 

I can see extreme snowfall when the conducive patterns return.  Some years huge, well above climo and several below,  but in the end averaging to climo. 

Tom's work is enlightening. The thing that sticks in my mind about his work is the focus he has on the eventual hand off to players that guide a favorable pattern, or reasoning they will not. He and others in his clan of strat enthusiasts focus on energy transport, GLAAM, AAM, the TPV, etc,  unusual methods to provide a clue to the coming season.  Learned a lot reading his work about coupling, the TPV, energy transport, etc. 

It should have worked last year, and this year he basically went with the disconnect and he is so far doing very well.  He call about  NAO is right on target. For him to really do a complete seasonal call and get icing on the cake would be for the pattern to turn snowy and cold in his window which if memory serves me correctly is  after Feb 20th to early March. @Isotherm please correct me if I am mistaken regarding my previous statement.

If anything the new warmer base state has made the study of meteorology even more difficult , and even more so in  the long range field. 

 

 

Thanks for the kind words re: my forecast. And Frd, that is correct. The window of opportunity would probably arise later February forward. As said, no guarantees, but certain variables may ameliorate by then.

Re, the NAO. It now appears almost a lock that the Dec-Jan-Feb mean NAO modality will average positive [in fact, per CPC data, I don't believe we have had more than 1-3 -NAO days since December 1st].

This will bring my formula to 90% exactly as far as the success/verification rate utilizing the years 1950-2019. As I've said prior, the formula is multifactorial. And yes, to PSU's note, the AAM periodicity/fluctuations is certainly involved in the formula, along with other variables. I had contemplated publishing a paper on the formula, but I'd like several more years of observing its performance.

 

[Isotherm]

And yes, I also agree with your point, @psuhoffman, regarding the altered base state, i.e., negative PDO structure, SSTA distortion in the WPAC, and this was certainly a variable in my winter outlook as well. When the waters are warmer in the macro-scale sense, the typical canonical weak Nino/neutral composites become much less meaningful. The jet flow is disrupted, hadley cells expand, among other things.

[frd]

2 hours ago, Isotherm said:

When the waters are warmer in the macro-scale sense, the typical canonical weak Nino/neutral composites become much less meaningful. The jet flow is disrupted, hadley cells expand, among other things.

Nice to hear confirmation about these features.  I believe last winter, along with you,  Tip from the NE Forum brought this point up as well. He mentioned that the SST structure/expanse  in the Pac was more so a swashing bathtub effect with warm waters over a large area, but no real focused anomaly.  

Some are saying we need some type of major Pac event to re-set the table. I am not sure whether the talks focused the need on Nina or Nino.  

 

 

[frd]

2 hours ago, Isotherm said:

Re, the NAO. It now appears almost a lock that the Dec-Jan-Feb mean NAO modality will average positive [in fact, per CPC data, I don't believe we have had more than 1-3 -NAO days since December 1st].

Tom, if you are able to comment would love to hear if you have any thoughts about a change in the NAO cycle over the next few winters. 

I have read research about ocean cycles and the AMO as well as lagged Ocean currents in the NW Atlantic as related to the solar minimum. Some are saying we might make an abrupt move to a multi-year cycle of - NAO over the next few years.  ( I assume they mean a winter -NAO not a warm season - NAO ) . That would, in my opinion, be a remarkable achievement based on the last 5 years of more. 

Of note, and whether it is a clue, or even important, not sure, but how about the record number of consecutive days the NAO was negative from late Spring to summer last year. A lot of talk back then of warm season blocking, but not as much -NAO action during the meat of winter.   

At one point I believe in August 2019 even bluewave posted and commented on the robust deep dive of the NAO and how it effected sensible weather leading to cool weather in the East, during an otherwise hot(est)  part of the year.   

Thanks as always. 

 

[North Balti Zen]

The dearth of clippers since I moved to the area in 2009 has been noticeable for me, I think. I grew up In Cincinnati and then central Ohio. For sure in Central Ohio in the 1980s we would pad seasonal snow totals with 1-3 inch events fairly frequently. I thought coming here from Memphis in 2009 I would see clippers again with some frequency, but they have been few and far between really over the 10 years I have been here.

[mattie g]

1 hour ago, North Balti Zen said:

The dearth of clippers since I moved to the area in 2009 has been noticeable for me, I think. I grew up In Cincinnati and then central Ohio. For sure in Central Ohio in the 1980s we would pad seasonal snow totals with 1-3 inch events fairly frequently. I thought coming here from Memphis in 2009 I would see clippers again with some frequency, but they have been few and far between really over the 10 years I have been here.

I remember them as a kid in South Jersey, but I've been in DC for 20 years now, and while I can't claim to have the encyclopedic knowledge of events that others have, I can't specifically recall more than a couple clippers in all the time I've been here. That's frankly preposterous.

[Isotherm]

19 hours ago, frd said:

Nice to hear confirmation about these features.  I believe last winter, along with you,  Tip from the NE Forum brought this point up as well. He mentioned that the SST structure/expanse  in the Pac was more so a swashing bathtub effect with warm waters over a large area, but no real focused anomaly.  

Some are saying we need some type of major Pac event to re-set the table. I am not sure whether the talks focused the need on Nina or Nino.  

 

 

 

19 hours ago, frd said:

Tom, if you are able to comment would love to hear if you have any thoughts about a change in the NAO cycle over the next few winters. 

I have read research about ocean cycles and the AMO as well as lagged Ocean currents in the NW Atlantic as related to the solar minimum. Some are saying we might make an abrupt move to a multi-year cycle of - NAO over the next few years.  ( I assume they mean a winter -NAO not a warm season - NAO ) . That would, in my opinion, be a remarkable achievement based on the last 5 years of more. 

Of note, and whether it is a clue, or even important, not sure, but how about the record number of consecutive days the NAO was negative from late Spring to summer last year. A lot of talk back then of warm season blocking, but not as much -NAO action during the meat of winter.   

At one point I believe in August 2019 even bluewave posted and commented on the robust deep dive of the NAO and how it effected sensible weather leading to cool weather in the East, during an otherwise hot(est)  part of the year.   

Thanks as always. 

 

 

@frd, I have read that research to which you refer, and believe it to hold value. There is a documented lagged-oceanic forcing, part of feedback cycle with the atmosphere. The interesting aspect about the NAO, as to why it is such a difficult 'beast' to forecast is its highly multifactorial nature. Unlike the PNA for example, which can be primarily forced by MJO or tropical Pacific disruptions, the NAO is forced by way of many disparate variables. That being said, there are propensities and correlations that can aid us in prognostication. Certainly, solar forcing is involved. As I believed I may have mentioned here before, there is a tendency for increased -NAO episodes immediately following the solar minimum point. Conversely, the years immediately preceding a solar minimum are often more +NAO slanted. This is not always the case but the tendency is quite noticeable. 

So, along those lines, yes, from a statistical and also physical forcing perspective, I think we will probably enter a period in which 2 or potentially 3 years out of the next 6 feature a -NAO in the means.

[psuhoffman]

1 hour ago, mattie g said:

I remember them as a kid in South Jersey, but I've been in DC for 20 years now, and while I can't claim to have the encyclopedic knowledge of events that others have, I can't specifically recall more than a couple clippers in all the time I've been here. That's frankly preposterous.

There were a lot in the 2000s. A couple in 2002/3. One in Jan 2004 gave MD 2-4”. There were several 1-3” clippers in 2004/5. A couple in Jan/feb 2007 and a big one Dec 2007, the only good snow that year. Then I remember a couple in 2009. 

This decade has been less common. There have been a few but we spent a lot of the decade in either a blocking pattern likely to squash clippers or a warm pattern where they would be way north of us. 

[psuhoffman]

40 minutes ago, Isotherm said:

 

 

@frd, I have read that research to which you refer, and believe it to hold value. There is a documented lagged-oceanic forcing, part of feedback cycle with the atmosphere. The interesting aspect about the NAO, as to why it is such a difficult 'beast' to forecast is its highly multifactorial nature. Unlike the PNA for example, which can be primarily forced by MJO or tropical Pacific disruptions, the NAO is forced by way of many disparate variables. That being said, there are propensities and correlations that can aid us in prognostication. Certainly, solar forcing is involved. As I believed I may have mentioned here before, there is a tendency for increased -NAO episodes immediately following the solar minimum point. Conversely, the years immediately preceding a solar minimum are often more +NAO slanted. This is not always the case but the tendency is quite noticeable. 

So, along those lines, yes, from a statistical and also physical forcing perspective, I think we will probably enter a period in which 2 or potentially 3 years out of the next 6 feature a -NAO in the means.

Given our regions reliance on the NAO I think this would get a collective hallelujah 

[frd]

2 hours ago, Isotherm said:

So, along those lines, yes, from a statistical and also physical forcing perspective, I think we will probably enter a period in which 2 or potentially 3 years out of the next 6 feature a -NAO in the means.

Thanks Tom. Great news to hear. I have to wonder myself the implication of the lag effect and whether next winter might be too soon to achieve it. However, there are couple intriguing elements to consider next winter, one of which is the well established - QBO .   

 

[jwilson]

Isn't the "hypothetical" end of climate change that the more extreme results become more common and there is less in the middle ground?  I think that hypothesis would correspond to the idea that snowfall in certain areas extends more to the bell-ends of the curve, while the middle chunk of the curve bottoms out.  Instead of a bell curve, we get a half-pipe.  As a few of you already discussed, the idea is feast-or-famine events (or seasons), while still maintaining the semblance of a traditional long-term average.

The one thing I've noticed as an adult now compared to a kid in the 80s and 90s: we have apparently shifted away from the four season model and are down to two: summer and winter.  This is purely observational on my end, and I don't know if data confirms it in any way.  Observing the trends, it seems we have less normal seasonal breakdowns.  Now the last few summers haven't been as hot as perhaps in the past, but we've shifted those temperature spikes away from the middle of summer and they can now extend deep into "fall" (September and October).

Likewise, we're seeing the extension of winter into spring months.  Even recent May months have been cool and wet, whereas April can swing wildly either way (from hot to cold).  Maybe it's just a short-term cycle and there is no long-term change.  I don't know for sure.  Like I said, I'm basing that off my own observations.  Perhaps my memory is also failing me as to how conditions existed when we were kids.

I will say the 90s really weren't all that great for snow growing up in Philadelphia.  Obviously we had at least two major remarkable events ('93 and '96), but outside of those, I don't think there was anything extraordinary about the decade.  The last ten years have been much more interesting, starting with '09-'10 of course.

I guess my final question would be: if global warming continues, would that see the eradication of "La Nina" conditions as we know them?  Maybe that's a stupid question, but thinking about the warming waters of the globe, I would think it'd be harder to get cool or negative temperature anomalies.  Or would that not be the case and instead we'd simply see more extreme versions of La Nina with intense negative spikes to couple with the opposite, as well?

[PrinceFrederickWx]

@jwilson

The summer creep into September is indeed a real change occurring. As I posted in the Extreme Run thread last fall, every September in the 2010's at BWI finished with above average temperatures except 2013, which was only -0.1 below. The new 1990-2020 norms, when released, will definitely increase the September temperature. 

March has varied wildly over the last decade and it's difficult to draw any conclusions. For BWI, March should return to being snowier on average than December under the 1990-2020 norms, but this is just a return to how it's always been historically.