Boston Snowfall, ENSO, and Blocking

[donsutherland1]

The following are some statistics related to the AO, ENSO and Boston's seasonal snowfall (1950-51 through 2012-13):

 

[weathafella]

The following are some statistics related to the AO, ENSO and Washington DC's seasonal snowfall (1950-51 through 2012-13):

 

Thanks for doing this Don. Do you have breakdowns on EPO correlated?

[donsutherland1]

Thanks for doing this Don. Do you have breakdowns on EPO correlated?

Jerry,

 

I'll try to run the EPO numbers tonight or tomorrow night.

[Ginx snewx]

Don the intro is wrong , you said "the following are some statistics related to the AO, ENSO and Washington DC's seasonal snowfall (1950-51 through 2012-13)" Your data supports what many of us thought,ENSO is less of an influence on snowfall in Boston than AO is. Would be interesting to run a EPO AO data set. Also interesting is the statistical increase in 60 inch snows when the AO is super positive. On another note todays 06 GEFS really drops the AO for the end of the month. 

[donsutherland1]

Don the intro is wrong , you said "the following are some statistics related to the AO, ENSO and Washington DC's seasonal snowfall (1950-51 through 2012-13)" Your data supports what many of us thought,ENSO is less of an influence on snowfall in Boston than AO is. Would be interesting to run a EPO AO data set. Also interesting is the statistical increase in 60 inch snows when the AO is super positive. On another note todays 06 GEFS really drops the AO for the end of the month. 

Thanks. I fixed the intro. The numbers are for Boston.

 

If I recall correctly, there were 7 winters where the AO averaged +1 or above. 1992-93 was one of them and it had more than 80" snow. The small sample size kind of skews the figures for that subset. In general, though, 60" or greater snowfall is a little more than twice as likely when there is blocking than when there isn't.

 

As for the EPO, I suspect that it would have less impact, but I won't know for sure until I run the numbers tonight. I'll also make a table based on the EPO and AO.

[weathafella]

Thanks. I fixed the intro. The numbers are for Boston.

 

If I recall correctly, there were 7 winters where the AO averaged +1 or above. 1992-93 was one of them and it had more than 80" snow. The small sample size kind of skews the figures for that subset. In general, though, 60" or greater snowfall is a little more than twice as likely when there is blocking than when there isn't.

 

As for the EPO, I suspect that it would have less impact, but I won't know for sure until I run the numbers tonight. I'll also make a table based on the EPO and AO.

Don, thanks for your hard work on our behalf.

Harkening to 1993-94, EPO can really rule the roost as it has arguably done this month despite other unfavorable teleconnections for much of the time.

[ApacheTrout]

That's some pretty neat data, Don.  Shows that having the AO drop below 0 makes it much easier for Boston to accumulate more than 40 inches of snow.

 

A numbers question for you, as I'm having trouble reconciling the values in two  three cells.  The sum of the percentages in the 50" or more and 60" or more columns should not exceed the total in the 40" or more column, right?  The sum can be less, but never more.  The sum of the data in the row where AO is <0  for those two columns is 71%, but the percentage of events with 40" or more was only 62%.  Am I reading that correctly?

[Ginx snewx]

Don, thanks for your hard work on our behalf.

Harkening to 1993-94, EPO can really rule the roost as it has arguably done this month despite other unfavorable teleconnections for much of the time.

My anecdotal thoughts without running any numbers is that -EPO winters do not feature huge snow numbers but rather a colder and dryer winter but have more depth days and are much more likely to have continuous snow cover.

[ORH_wxman]

My anecdotal thoughts without running any numbers is that -EPO winters do not feature huge snow numbers but rather a colder and dryer winter but have more depth days and are much more likely to have continuous snow cover.

 

 

BOS has had 13 winters with >60" since 1950....this is the composite 500mb anomaly for those 12 winters:

 

 

 

 

 

 

The EPO is definitely negative in this composite, but its not overly dominant. Interestingly, this is a solid -PNA pattern and a -NAO. If you go by a straight count though, the PNA is negative in only 7 out of the 13 winters...however, they are much stronger -PNA patterns than the positive PNA patterns, so they dominate the composite. Years like '55-'56, '81-'82, '92-'93, '08-'09, and '10-'11 dominate the PNA signal. Only really '60-'61, '02-'03, and perhaps '63-'64 were strongly positive PNA winters.

[donsutherland1]

That's some pretty neat data, Don.  Shows that having the AO drop below 0 makes it much easier for Boston to accumulate more than 40 inches of snow.

 

A numbers question for you, as I'm having trouble reconciling the values in two  three cells.  The sum of the percentages in the 50" or more and 60" or more columns should not exceed the total in the 40" or more column, right?  The sum can be less, but never more.  The sum of the data in the row where AO is <0  for those two columns is 71%, but the percentage of events with 40" or more was only 62%.  Am I reading that correctly?

The 50" or more seasons include those with 60" or more snow. I didn't use 50"-59.9" and 60" or more.

 

Therefore, using the row in question, AO- winters saw 62% of seasons with 40" or more snow. Almost 70% of those 40" or greater seasons saw 50" or more snow and about 45% of those 40" or greater seasons had 60" or more snowfall.

 

The numbers are as follows for AO- winters:

 

Total winters (1950-51 through 2012-13): 40

40" or more snowfall: 25 winters

50" or more snowfall: 17 winters

60" or more snowfall: 11 winters

[ApacheTrout]

The 50" or more seasons include those with 60" or more snow. I didn't use 50"-59.9" and 60" or more.

 

Therefore, using the row in question, AO- winters saw 62% of seasons with 40" or more snow. Almost 70% of those 40" or greater seasons saw 50" or more snow and about 45% of those 40" or greater seasons had 60" or more snowfall.

 

The numbers are as follows for AO- winters:

 

Total winters (1950-51 through 2012-13): 40

40" or more snowfall: 25 winters

50" or more snowfall: 17 winters

60" or more snowfall: 11 winters

 

Understood.  Thanks for taking the time to explain it.

[Ginx snewx]

The 50" or more seasons include those with 60" or more snow. I didn't use 50"-59.9" and 60" or more.

 

Therefore, using the row in question, AO- winters saw 62% of seasons with 40" or more snow. Almost 70% of those 40" or greater seasons saw 50" or more snow and about 45% of those 40" or greater seasons had 60" or more snowfall.

 

The numbers are as follows for AO- winters:

 

Total winters (1950-51 through 2012-13): 40

40" or more snowfall: 25 winters

50" or more snowfall: 17 winters

60" or more snowfall: 11 winters

Will has 13 over 60 you have 11????

[Ginx snewx]

BOS has had 13 winters with >60" since 1950....this is the composite 500mb anomaly for those 12 winters:

 

 

 

 

 

 

The EPO is definitely negative in this composite, but its not overly dominant. Interestingly, this is a solid -PNA pattern and a -NAO. If you go by a straight count though, the PNA is negative in only 7 out of the 13 winters...however, they are much stronger -PNA patterns than the positive PNA patterns, so they dominate the composite. Years like '55-'56, '81-'82, '92-'93, '08-'09, and '10-'11 dominate the PNA signal. Only really '60-'61, '02-'03, and perhaps '63-'64 were strongly positive PNA winters.

Sup..

[ORH_wxman]

 

Will has 13 over 60 you have 11????

 

His was during -AO winters...the other 2 occurred during +AO winters.

[Ginx snewx]

 

 

His was during -AO winters...the other 2 occurred during +AO winters.

got it, thanks

[It's Always Sunny]

Don the intro is wrong , you said "the following are some statistics related to the AO, ENSO and Washington DC's seasonal snowfall (1950-51 through 2012-13)" Your data supports what many of us thought,ENSO is less of an influence on snowfall in Boston than AO is. Would be interesting to run a EPO AO data set. Also interesting is the statistical increase in 60 inch snows when the AO is super positive. On another note todays 06 GEFS really drops the AO for the end of the month. 

I find that interesting as well, but I think the difference between 14% and 8% is minute. When I think of ENSO's influence on our snowfall here, I just think of our winter of 2011-2012 where we were in a La Nina phase, but got jack sh*t for snowfall. I also agree with many that an EPO and AO correlation would be cool to see.

[ORH_wxman]

I find that interesting as well, but I think the difference between 14% and 8% is minute. When I think of ENSO's influence on our snowfall here, I just think of our winter of 2011-2012 where we were in a La Nina phase, but got jack sh*t for snowfall. I also agree with many that an EPO and AO correlation would be cool to see.

 

 

The winter before in 2010-2011 was an even stronger La Nina and we got buried.

 

BOS snowfall has little correlation to ENSO overall. Though a weak El Nino tends to be the "sweet spot" in an otherwise very uncorrelating dataset. The AO is definitely more important.

[It's Always Sunny]

The winter before in 2010-2011 was an even stronger La Nina and we got buried.

 

BOS snowfall has little correlation to ENSO overall. Though a weak El Nino tends to be the "sweet spot" in an otherwise very uncorrelating dataset. The AO is definitely more important.

True. Guess that just reinforces the fact that ENSO doesn't necessarily correlate well with Boston winter snowfall. I found a cool link below that goes along with ENSO and snowfall:

 

[donsutherland1]

Boston's seasonal snowfall and the EPO:

 

[ORH_wxman]

Thanks for the stats on the EPO Don. Definitely some interesting stats. Strongly +EPO looks to favor the bad seasons of <40", however, weakly positive EPO doesn't seem to hurt much.

 

The strongest correlation remains the AO, with ENSO having little effect.

[donsutherland1]

Thanks for the stats on the EPO Don. Definitely some interesting stats. Strongly +EPO looks to favor the bad seasons of <40", however, weakly positive EPO doesn't seem to hurt much.

 

The strongest correlation remains the AO, with ENSO having little effect.

 

I agree. Hopefully, even if the winter has a predominantly positive AO, there will be periods where there is sufficient blocking to coincide with storminess.

[weathafella]

Thanks much Don, One can hope the AO forecasts for the winter of positive are wrong.

[donsutherland1]

Thanks much Don, One can hope the AO forecasts for the winter of positive are wrong.

I agree. It will be interesting to see what happens to the blocking that is forecast to develop in the extended range.

[CoolMike]

Whats most interesting to me in the ENSO EPO chart is how strong the cross-effect is between ENSO States and the effect of the EPO on snow totals.

[Damage In Tolland]

The AO is vastly overrated. As long as the Pacific cooperates..NYC north can be wintry

[weathafella]

The AO is vastly overrated. As long as the Pacific cooperates..NYC north can be wintry

So Don's stats are figments?

[CoastalWx]

So Don's stats are figments?

LOL we just ignore them. There is a reason why the Pacific sometimes can't cooperate when

We have a strong +AO.

[CoastalWx]

This is good stuff. Thanks Don.

[Damage In Tolland]

So Don's stats are figments?

They don't show bad winters with a pos AO

[Damage In Tolland]

And really my point is that the PAC trumps the Atlantic. It drives the bus. That's what we are seeing this winter