January 2011 Thoughts: Area of Warmth Could Be Somewhat Limited

[donsutherland1]

To date, the Arctic Oscillation (AO) has averaged -2.42. December 2010 is likely to average -2 or below for only the sixth time since recordkeeping on the AO began in 1950. In all five prior cases, January had an AO < 0. In 4/5 (80%) of those cases it averaged -0.900 or below In a slightly broader sample, all nine cases in which the December AO averaged -1.7 or below also saw a negative average AO in January. Both cases that saw extreme blocking (-5 or below AO on at least one day in December) had a negative AO in January.

The question arises as to whether the AO, which has dominated the December pattern and mitigated the impact of the current La Niña will have a similar impact in January. Already, the excessive December snowfall in Boston and New York City hints that Winter 2010-11 will likely see above normal snowfall in those cities.

As no reconstructed AO figures exist prior to 1950, I used the reconstructed NAO figures to estimate the AO. To do so, I calculated the linear relationship between the reconstructed NAO data for the January 1950-July 2001 (latest date for the reconstructed figures) and the AO. The linear regression came out to 0.330744 Reconstructed NAO - 0.15499. The coefficients of correlation and determination were respectively 0.577427 and 0.333422 (not great, but better than no idea whatsoever). I then estimated the AO for all January cases prior to 1950 during which the ENSO Region 3.4 anomaly was -1 or below (likely in January 2011).The following January cases had an AO of < 0: 1893, 1917, and 1943. An examination of the data found that 5/6 (83%) cases when the AO averaged -0.1 or below in January saw an area of cool anomalies over a large part of the eastern U.S. That is in contrast to the composite for all La Niña cases in January when the ENSO Region 3.4 anomaly was -1 or below (1890, 1893, 1894, 1917, 1943, 1950, 1951, 1955, 1956, 1971, 1974, 1976,1985, 1989, 1999, 2000, 2008).

500 mb Height Anomalies:

Composite of all January cases with an ENSO Region 3.4 anomaly of -1 or below:

Composite of January cases with an ENSO Region 3.4 anomaly of -1 or below and a monthly AO of -0.1 or below:

1000 mb Temperature Anomalies*:

Composite of all January cases with an ENSO Region 3.4 anomaly of -1 or below:

Composite of January cases with an ENSO Region 3.4 anomaly of -1 or below and a monthly AO of -0.1 or below:

* Note: No surface data is available for the larger 1871-2010 data set. However, another data set that runs from 1895-2000 has surface temperature anomalies and those mirror the 1000 mb figures.

Composite temperature anomalies for January cases with an ENSO Region 3.4 anomaly of -1 or below (1895-2010):

Composite temperature anomalies for January cases with an ENSO Region 3.4 anomaly of -1 or below (1895-2010):

Composite temperature anomalies for January cases with an ENSO Region 3.4 anomaly of -1 or below but excluding the extremely cold 1985 (1895-2010):

Conclusion:

The northern Mid-Atlantic region could experience near normal or somewhat below normal readings for January, though January won't be as cold as December was. Southern New England could experience below normal readings. A large area stretching across the Great Lakes region, Northern Plains, and at least the Pacific Northwest could be colder than normal. This area includes southern Ontario and southern Quebec. The Southern Plains, Gulf Coast, and Southeast will likely wind up on the warm side of normal. In terms of precipitation, the area running from eastern Texas across the Gulf Coast and then up the Eastern Seaboard will likely see less than normal precipitation. The West Coast could also be drier than normal. Near normal precipitation is likely in southern Ontario and southern Quebec.

[HM]

Great work Don. Looks good.

[Isotherm]

Great work as usual Don. Strongly agree w/ the idea of a colder than normal January across the northern tier.

[RUNNAWAYICEBERG]

good stuff...

and the good news keeps on turning for this winter. even a normal jan temp wise is plenty good enough for snow chances. and the the southern stream has actually been open for business, this nina chick is behaving quite strangely!

[easternsnowman]

Great work Don! I agree with your ideas.

[am19psu]

As no reconstructed AO figures exist prior to 1950, I used the reconstructed NAO figures to estimate the AO. To do so, I calculated the linear relationship between the reconstructed NAO data for the January 1950-July 2001 (latest date for the reconstructed figures) and the AO. The linear regression came out to -0.330744 Reconstructed NAO - 0.15499. The coefficient of correlation was 0.333422 (not great, but better than no idea whatsoever).

Hey Don, great stuff, as always. Did you try limiting your regression to cold season NAO/AO values only? In the research I was doing in the lead up to winter, I remember reading a paper (and sorry I don't remember which) that showed that the correlation between the AO and the NAO was strongest in the cold season (which makes subjective sense, too). You might make your results more robust by limiting your sample to Oct-Mar or some similar time frame. Thanks again for taking the time to do all of this work.

[donsutherland1]

Hey Don, great stuff, as always. Did you try limiting your regression to cold season NAO/AO values only? In the research I was doing in the lead up to winter, I remember reading a paper (and sorry I don't remember which) that showed that the correlation between the AO and the NAO was strongest in the cold season (which makes subjective sense, too). You might make your results more robust by limiting your sample to Oct-Mar or some similar time frame. Thanks again for taking the time to do all of this work.

Thank you for the suggestion, am19psu. I didn't limit the regression to the cold seasons, but will rerun the results tonight to see if they make a material difference.

[Damage In Tolland]

Great stuff Don. Good to see that all those forecasts of a warm, torch winter in the East are not looking so hot shall we say

[donsutherland1]

Great stuff Don. Good to see that all those forecasts of a warm, torch winter in the East are not looking so hot shall we say

I completely agree. Hopefully, it won't be too long before a more favorable pattern for additional snowfall recurs.

[snowstormcanuck]

Conclusion:

The northern Mid-Atlantic region could experience near normal or somewhat below normal readings for January, though January won't be as cold as December was. Southern New England could experience below normal readings. A large area stretching across the Great Lakes region, Northern Plains, and at least the Pacific Northwest could be colder than normal. This area includes southern Ontario and southern Quebec. The Southern Plains, Gulf Coast, and Southeast will likely wind up on the warm side of normal. In terms of precipitation, the area running from eastern Texas across the Gulf Coast and then up the Eastern Seaboard will likely see less than normal precipitation. The West Coast could also be drier than normal. Near normal precipitation is likely in southern Ontario and southern Quebec.

With that Atlantic vortex spinning in place during -NAO/-AO phases, I find this tough to believe. It's been so proficient at deflecting synoptic precipitation makers to our SW through the Ohio Valley and/or to our E along the East Coast. Here in Toronto we're roughly running a 2.5-3.5" precipitation deficit for November and December. Assuming blocking reemerges, I would think more of the same should be expected for January, especially with the climotologically favoured storm track shifting SE with time.

[donsutherland1]

With that Atlantic vortex spinning in place during -NAO/-AO phases, I find this tough to believe. It's been so proficient at deflecting synoptic precipitation makers to our SW through the Ohio Valley and/or to our E along the East Coast. Here in Toronto we're roughly running a 2.5-3.5" precipitation deficit for November and December. Assuming blocking reemerges, I would think more of the same should be expected for January, especially with the climotologically favoured storm track shifting SE with time.

I expect blockiness, but not the kind of severe blocking that had occurred during December. I believe some time in February (possibly the last week or two?) might witness a return of severe/extreme blocking.

[snowstormcanuck]

I expect blockiness, but not the kind of severe blocking that had occurred during December. I believe some time in February (possibly the last week or two?) might witness a return of severe/extreme blocking.

Well Don, hopefully this relaxing of the blocking proves to be fruitful. You wouldn't know it looking at the last several runs of the GFS/GEFS.

[Organizing Low]

Well Don, hopefully this relaxing of the blocking proves to be fruitful. You wouldn't know it looking at the last several runs of the GFS/GEFS.

each time the blocking has relaxed we've gotten rain.

ottawa is around 12 inches of snow, 30% of normal to date.

luckily montreal had a totally fluke retro river flow event when Ji was in town.

as amazing as it is what has happened across the US east coast the past 2 season,

to me it is just as remarkable what has happened across eastern canada the past 2 winters to balance the east coast....stunning really on both accounts.

what an incredible stretch of blocking, i would never have beleived such a thing could persist and translate into such a reverse paradigm .

not that 90% of eastern Canadians are complaining....i think they are just fine with this New World Order .....ie THEY can have it AND keep it as long as you want, thank you..

[okie333]

I expect blockiness, but not the kind of severe blocking that had occurred during December. I believe some time in February (possibly the last week or two?) might witness a return of severe/extreme blocking.

Mark my words, before January 20th you will see the error of your ways.

[wxmx]

Ensembles are now hinting at a new dip in the AO... with the more aggressive members rivaling the Dec block... I wouldn't buy it just jet, erring on the side of caution, but signals are getting stronger for a continued period of high latitude blocking.

[Ottawa Blizzard]

each time the blocking has relaxed we've gotten rain.

ottawa is around 12 inches of snow, 30% of normal to date.

luckily montreal had a totally fluke retro river flow event when Ji was in town.

as amazing as it is what has happened across the US east coast the past 2 season,

to me it is just as remarkable what has happened across eastern canada the past 2 winters to balance the east coast....stunning really on both accounts.

what an incredible stretch of blocking, i would never have beleived such a thing could persist and translate into such a reverse paradigm .

not that 90% of eastern Canadians are complaining....i think they are just fine with this New World Order .....ie THEY can have it AND keep it as long as you want, thank you..

I really hope Don is right, but the GFS has been fairly consistent in predicting a torch in these parts, similar to 1990 and 2006, albeit with less snow. I'm still in Toronto at the moment and it really is feeling like the new Vancouver. I drove down to Buffalo yesterday (chose the wrong day unfortunately as with Canada playing in the World Juniors the lineup to get back into canada in the evening was massive!) and it was amazing how much more snow they had. I may as well have been driving to a different planet.

It really is amazing what this blocking has done to our weather over the past two years. I mean, 1976-77 apparently also saw a major blocking regime, and yet December and january that year were frigid in tehse parts, along with the Ohio Valley and mid atlantic.

[Ottawa Blizzard]

Ensembles are now hinting at a new dip in the AO... with the more aggressive members rivaling the Dec block... I wouldn't buy it just jet, erring on the side of caution, but signals are getting stronger for a continued period of high latitude blocking.

I really am starting to think that Ontario is in for a stretch of very mild winters. That is not based on science, just on gut feeling.

[Ottawa Blizzard]

Don, was 1964-65 a La nina year? That winter saw a very mild and relatively snowless December and early January in these parts. Perhaps there was high latitude blocking that winter?

December 1964: http://www.climate.weatheroffice.gc.ca/climateData/dailydata_e.html?Prov=XX&timeframe=2&StationID=4337&Day=1&Month=12&Year=1964&cmdB1=Go

January 1965: http://www.climate.weatheroffice.gc.ca/climateData/dailydata_e.html?timeframe=2&Prov=XX&StationID=4337&Year=1965&Month=1&Day=1

Interestingly, December 1965 was also unusually mild in Ottawa - even milder than this December. January 1966 saw one of the top 5 snowstorms ever for both Toronto and Ottawa.

December 1965: http://www.climate.weatheroffice.gc.ca/climateData/dailydata_e.html?Prov=XX&timeframe=2&StationID=4337&Day=1&Month=12&Year=1965&cmdB1=Go (note how mild New Years Eve was - even milder than this year is forecast to be!)

January 1966: http://www.climate.weatheroffice.gc.ca/climateData/dailydata_e.html?timeframe=2&Prov=XX&StationID=4337&Year=1966&Month=1&Day=1 (take a look at that storm at the end of the month!)

[uncle W]

the la nina winters that started out with a very cold December were cold in January too...

[wxmx]

I really am starting to think that Ontario is in for a stretch of very mild winters. That is not based on science, just on gut feeling.

Prospects aren't looking good, but I'm having a hard time imagining that a nice cold/snowy period isn't in the cards for Ottawa in the Jan-Mar period... but probably not yet. I'm harbinger of bad news for you, but good news for most in this forum...RaleighWX's Euro NAO index calculation is trending more negative...and with the old 300/-300 scale, this graph would show almost completely blue.

[donsutherland1]

Ensembles are now hinting at a new dip in the AO... with the more aggressive members rivaling the Dec block... I wouldn't buy it just jet, erring on the side of caution, but signals are getting stronger for a continued period of high latitude blocking.

Although I don't yet favor a near-term return of severe or extreme blocking, there is some prospect that the experience following extreme December 1976 and 2009 blocks could play out. If so, the curernt blocking regime could persist through at least mid-January (latter case) and additional episodes of severe/extreme blocking could be expected (both cases). Currently, I give odds of that development's occurring around 25%. More likely, IMO, are scenarios along the lines of 1995-96 and 2000-01 (weaker La Niñas with a December AO < -2).

[Rib]

Great stuff as always Don. Usually La-nina seems to just have one really cold/sometimes snowy month, then the rest of the winter average above normal temperature wise, so a winter where we can have more than that would be great. 2000-2001 never got very warm, even if the rest of the winter wasn't as cold as December. Nice analog.

[donsutherland1]

Thanks Rib. It will be interesting to see how things play out.

[vortmax]

While the blocking pattern has been snow-poor for WNY from a synoptic sense, it really turned on the LES machines. However, going into Jan with cooling lakes it will be harder and harder to jump start them. With that said, if we get some really cold 850 temps to come down then the LES may just sustain us through Jan as well. ROC broke their december snow record (46.4") almost soley from LES...amazing. I'm looking forward to Jan and hoping to get at least one good synoptic event along with the meso stuff...

[PNW guy]

Conclusion:

The northern Mid-Atlantic region could experience near normal or somewhat below normal readings for January, though January won't be as cold as December was. Southern New England could experience below normal readings. A large area stretching across the Great Lakes region, Northern Plains, and at least the Pacific Northwest could be colder than normal. This area includes southern Ontario and southern Quebec. The Southern Plains, Gulf Coast, and Southeast will likely wind up on the warm side of normal. In terms of precipitation, the area running from eastern Texas across the Gulf Coast and then up the Eastern Seaboard will likely see less than normal precipitation. The West Coast could also be drier than normal. Near normal precipitation is likely in southern Ontario and southern Quebec.

From someone who lives in the Pacific NW-this winter has NOT turned out to be cooler than normal...yet. The big -AO is not helping matters here at all. So we shall see what happens. January still is yet to come but my expectations for a "record" winter have been greatly diminished. I must say...we have had tremendous amounts of precip in western WA so that part of La Nina has met expectations. Not so sure of the "cooler" party anymore.

Still looks pretty good for all of you the the northeast though.

[A-L-E-X]

I expect blockiness, but not the kind of severe blocking that had occurred during December. I believe some time in February (possibly the last week or two?) might witness a return of severe/extreme blocking.

hey Don, I find your three analogs quite interesting: 1893, 1917 and 1943. Are you going to roll these forward to the following months? Because, I believe 1893 featured the snowiest March ever, and the second snowiest month NYC has ever had, which, along with 1955-56, gives us two cold/snowy March analogs. 1917 of course, seems to be matching up really well already. And I believe 1943 was one of those severely cold WW2 winters in which both eastern north america and western europe faced great hardship. As a matter of fact, both World Wars featured extreme winters and both seem to be well represented in the analogs.

[A-L-E-X]

Although I don't yet favor a near-term return of severe or extreme blocking, there is some prospect that the experience following extreme December 1976 and 2009 blocks could play out. If so, the curernt blocking regime could persist through at least mid-January (latter case) and additional episodes of severe/extreme blocking could be expected (both cases). Currently, I give odds of that development's occurring around 25%. More likely, IMO, are scenarios along the lines of 1995-96 and 2000-01 (weaker La Niñas with a December AO < -2).

Don, do you think you might add 1966-67 to the list of analogs? I believe all three of the above cases featured la ninas after el ninos and that might be playing a contributory factor in why we are experiencing this kind of pattern.

[donsutherland1]

Don, do you think you might add 1966-67 to the list of analogs? I believe all three of the above cases featured la ninas after el ninos and that might be playing a contributory factor in why we are experiencing this kind of pattern.

I didn't add 1966-67 to the list, because the ENSO Region 3.4 anomaly was > -0.5 throughout the winter.

[donsutherland1]

From someone who lives in the Pacific NW-this winter has NOT turned out to be cooler than normal...yet. The big -AO is not helping matters here at all. So we shall see what happens. January still is yet to come but my expectations for a "record" winter have been greatly diminished. I must say...we have had tremendous amounts of precip in western WA so that part of La Nina has met expectations. Not so sure of the "cooler" party anymore.

Still looks pretty good for all of you the the northeast though.

There is actually an inverse relationship between the AO and Pacific Northwest temperatures. In other words, an AO+ correlates with cooler than normal readings in the Pacific Northwest. An AO- correlates with warmer than normal readings. The PNA has a direct relationship with Pacific Northwest temperatures. However, the AO has been so severely negative, that it has overwhelmed all other factors, including the generally modestly negative PNA, which would normally correlate with cooler readings in the Pacific Northwest. I still believe that the Pacific Northwest's most impressive winter weather (cold and snowfall opportunities) will occur in the second half of January. There is a chance that by that time, the coldest air could be on our side of the globe, hence the potential for some severe cold could exist. Farther ahead, I do believe a sustained and potentially strong blocking regime will redevelop at some point in February (possibly latter 1-2 weeks?), but that's subject to change given how far out it is.

[A-L-E-X]

There is actually an inverse relationship between the AO and Pacific Northwest temperatures. In other words, an AO+ correlates with cooler than normal readings in the Pacific Northwest. An AO- correlates with warmer than normal readings. The PNA has a direct relationship with Pacific Northwest temperatures. However, the AO has been so severely negative, that it has overwhelmed all other factors, including the generally modestly negative PNA, which would normally correlate with cooler readings in the Pacific Northwest. I still believe that the Pacific Northwest's most impressive winter weather (cold and snowfall opportunities) will occur in the second half of January. There is a chance that by that time, the coldest air could be on our side of the globe, hence the potential for some severe cold could exist. Farther ahead, I do believe a sustained and potentially strong blocking regime will redevelop at some point in February (possibly latter 1-2 weeks?), but that's subject to change given how far out it is.

Later in Feb and especially March is when analogs like 1892-93 and 1955-56 could come into play....