February 2011 Thoughts: Another 'Atypical' La Niña Month

[donsutherland1]

In the wake of a storm that dumped a swath of 4” and greater snows across parts of the northern Mid-Atlantic and southern New England regions, the coldest air mass to date is pouring into the East. That Arctic blast should solidify and expand the cold anomalies that have predominated there in non-La Niña fashion.

A convergence of factors suggests that February, typically warm across a wide part of the U.S./southern Ontario/southern Quebec, with cold anomalies generally confined to the West during moderate/strong La Niña events, will defy post-1950 La Niña climatology. Instead, it will likely resemble the “cold” La Niña events that appeared from time to time in the early 19^th century, and then in a remarkable cluster in the early 20^th century.

• Precedent with the 1872-73, 1903-04, 1909-10, and 1916-17 moderate/strong “cold” La Niña cases suggests that February will closely resemble the winter anomalies to date.

• Historic snowfall climatology based on the December snowfall (posted here on December 28, 2010) suggested that New York City should reach or exceed 40” seasonal snowfall and Boston should reach or exceed 50” snowfall. That idea is well on the way to verifying. After today’s snowfall, both cities are on the brink of attaining those figures (Boston: 49.6”; New York City: 36.1”). That historic experience and also snowfall-La Niña experience points to a continuation of above to much above normal snowfall from Philadelphia to Boston.

For example, if one took all the La Niña cases when New York City received November-December snowfall of 8” or more, the following winters show up: 1872-73 (cold moderate/strong La Niña), 1898-99, 1916-17 (cold moderate/strong La Niña), 1933-34, and 1967-68. In 4/5 (80%) cases, New York City picked up 10” or more snowfall in February. Three of those cases saw NYC receive 15” or more snowfall. In 50% of those cases (Boston’s monthly snowfall record does not extend back to 1872-73), Boston picked up 30” or more monthly snowfall. In addition, those winters featured widespread cold in the East. All of those winters featured one or more substantial Arctic blasts in February (something that is showing up on the long-range of the 1/21/2011 12z GFS).

• February is likely to feature an AO-/PNA+ set up for the month as a whole. Following severe to extreme December AO blocking episodes, renewed strong blocking develops either in late January or sometime in February. The latest ensemble guidance is hinting at the rise of a new AO- regime sometime during the first week in February. Drawing upon past severe/extreme December blocking episodes with regard to redevelopment of severe blocking, the most significant blocking could be in place around mid-February. Hence, even if the PNA+ erodes, a severe AO- block could sustain a generally cold pattern. Moreover, an EPO- could assure that the coldest air remains on our side of the Northern Hemisphere, setting the stage for additional Arctic intrusions. Finally, in 80% of La Niña/PDO- cases, when the January PNA averaged +0.50 or above, February also featured a generally positive PNA.

The following charts illustrate the temperature anomalies associated with the “cold” moderate/strong La Niña events, La Niña-early snowfall climatology, and AO-/PNA+ La Niña cases in February:

Composite “Cold” La Niña Cases:

Composite Snowfall Climatology/La Niña Cases:

Composite AO-/PNA+ Cases in February during La Niña Events:

Conclusions:

• Given the above factors, I believe the Middle Atlantic region, New England, Ohio Valley/Great Lakes, Northern Plains and Central Plains will likely feature colder than normal readings for the month. The Pacific Northwest, Southern Plains (particularly Texas), and probably the Gulf Coast into the Southeast will probably wind up on the milder side of normal, though a cold shot at some point is possible.

• February will likely feature above-to-much above normal snowfall in the northern Mid-Atlantic region and southern New England. Philadelphia, Newark, New York City, Providence, and Boston will likely see above normal to excessive snowfall for the month. February will likely feature more snowfall than January in Ottawa and similar amounts to January in Toronto. A KU-type snowstorm cannot be ruled out.

• February will likely feature one or two significant Arctic intrusions that could send temperatures below -25°C (-13°F) and possibly to or below -30°C (-22°F) in Ottawa and Montreal. Toronto could be a shade warmer, but should see one or more -20°C (-4°F) minimum temperatures. Single digit lows should occur on one or more days in such cities as Philadelphia, New York City, and Boston and a subzero low in any of those cities is not out of the realm of possibility.

[uncle W]

In the wake of a storm that dumped a swath of 4” and greater snows across parts of the northern Mid-Atlantic and southern New England regions, the coldest air mass to date is pouring into the East. That Arctic blast should solidify and expand the cold anomalies that have predominated there in non-La Niña fashion.

A convergence of factors suggests that February, typically warm across a wide part of the U.S./southern Ontario/southern Quebec, with cold anomalies generally confined to the West during moderate/strong La Niña events, will defy post-1950 La Niña climatology. Instead, it will likely resemble the “cold” La Niña events that appeared from time to time in the early 19^th century, and then in a remarkable cluster in the early 20^th century.

• Precedent with the 1872-73, 1903-04, 1909-10, and 1916-17 moderate/strong “cold” La Niña cases suggests that February will closely resemble the winter anomalies to date.

• Historic snowfall climatology based on the December snowfall (posted here on December 28, 2010) suggested that New York City should reach or exceed 40” seasonal snowfall and Boston should reach or exceed 50” snowfall. That idea is well on the way to verifying. After today’s snowfall, both cities are on the brink of attaining those figures (Boston: 49.6”; New York City: 36.1”). That historic experience and also snowfall-La Niña experience points to a continuation of above to much above normal snowfall from Philadelphia to Boston.

For example, if one took all the La Niña cases when New York City received November-December snowfall of 8” or more, the following winters show up: 1872-73 (cold moderate/strong La Niña), 1898-99, 1916-17 (cold moderate/strong La Niña), 1933-34, and 1967-68. In 4/5 (80%) cases, New York City picked up 10” or more snowfall in February. Three of those cases saw NYC receive 15” or more snowfall. In 50% of those cases (Boston’s monthly snowfall record does not extend back to 1872-73), Boston picked up 30” or more monthly snowfall. In addition, those winters featured widespread cold in the East. All of those winters featured one or more substantial Arctic blasts in February (something that is showing up on the long-range of the 1/21/2011 12z GFS).

• February is likely to feature an AO-/PNA+ set up for the month as a whole. Following severe to extreme December AO blocking episodes, renewed strong blocking develops either in late January or sometime in February. The latest ensemble guidance is hinting at the rise of a new AO- regime sometime during the first week in February. Drawing upon past severe/extreme December blocking episodes with regard to redevelopment of severe blocking, the most significant blocking could be in place around mid-February. Hence, even if the PNA+ erodes, a severe AO- block could sustain a generally cold pattern. Moreover, an EPO- could assure that the coldest air remains on our side of the Northern Hemisphere, setting the stage for additional Arctic intrusions. Finally, in 80% of La Niña/PDO- cases, when the January PNA averaged +0.50 or above, February also featured a generally positive PNA.

The following charts illustrate the temperature anomalies associated with the “cold” moderate/strong La Niña events, La Niña-early snowfall climatology, and AO-/PNA+ La Niña cases in February:

Composite “Cold” La Niña Cases:

Composite Snowfall Climatology/La Niña Cases:

Composite AO-/PNA+ Cases in February during La Niña Events:

Conclusions:

• Given the above factors, I believe the Middle Atlantic region, New England, Ohio Valley/Great Lakes, Northern Plains and Central Plains will likely feature colder than normal readings for the month. The Pacific Northwest, Southern Plains (particularly Texas), and probably the Gulf Coast into the Southeast will probably wind up on the milder side of normal, though a cold shot at some point is possible.

• February will likely feature above-to-much above normal snowfall in the northern Mid-Atlantic region and southern New England. Philadelphia, Newark, New York City, Providence, and Boston will likely see above normal to excessive snowfall for the month. February will likely feature more snowfall than January in Ottawa and similar amounts to January in Toronto. A KU-type snowstorm cannot be ruled out.

• February will likely feature one or two significant Arctic intrusions that could send temperatures below -25°C (-13°F) and possibly to or below -30°C (-22°C) in Ottawa and Montreal. Toronto could be a shade warmer, but should see one or more -20°C (-4°F) minimum temperatures. Single digit lows should occur on one or more days in such cities as Philadelphia, New York City, and Boston and a subzero low in any of those cities is not out of the realm of possibility.

Nice write up Don...This winter is rapidly becoming a classic...

[Mallow]

Don,

I hope you're very, very wrong about a +PNA February.

[pcbjr]

Don,

Given your map: "Composite AO-/PNA+ Cases in February during La Niña Events", why would "the Gulf Coast into the Southeast ... probably wind up on the milder side of normal"?

Thanks!

[donsutherland1]

Don,

Given your map: "Composite AO-/PNA+ Cases in February during La Niña Events", why would "the Gulf Coast into the Southeast ... probably wind up on the milder side of normal"?

Thanks!

The AO-/PNA+ cases are just one input into my thoughts. I was also considering the cold La Niña cases irrespective of AO/PNA and the La Niña-snowfall climatology cases. Incidentally, the idea of wamth running across Texas into part of the Gulf Coast shows up on the CFS.

[donsutherland1]

Don,

I hope you're very, very wrong about a +PNA February.

I hope that there are enough PNA- days so that the Pacific Northwest can experience some notable winter weather, but believe that the PNA will average positive for the month as a whole.

[donsutherland1]

Nice write up Don...This winter is rapidly becoming a classic...

Thanks Uncle W. I agree with you about the winter's becoming a classic.

[pcbjr]

The AO-/PNA+ cases are just one input into my thoughts. I was also considering the cold La Niña cases irrespective of AO/PNA and the La Niña-snowfall climatology cases. Incidentally, the idea of wamth running across Texas into part of the Gulf Coast shows up on the CFS.

Thanks for the explanation!

You are truly an asset to all of us who are learning!

[Ottawa Blizzard]

For Ottawa the February to beat is February 1993, by far. A mean of -13.6C (the coldest February of the past 30 years), and a very snowy one too. What I would do for a storm like February 13th,1993 or February 21st-22nd, 1993!! Looking further back, two other amazing Februaries are those of 1967 and 1979.

[Ottawa Blizzard]

February 1904 was another awesome month by the looks of it. All would happy. Snow and vodka cold.

http://www.climate.weatheroffice.gc.ca/climateData/dailydata_e.html?Prov=XX&timeframe=2&StationID=4333&Day=1&Month=2&Year=1904&cmdB1=Go

[SACRUS]

Don,

great stuff as always. The cold is king this season and the blocking has clearly produced the pattern to run counter to a more typical La Nina. The snowfall stats when coupled with the AO stats are telling for the northeast. I hope our friends South of Philly can get in on some of this winters treats. I wonder if we see a repeat of last yearsrs pattern leading up to and during the warm season.

Tony

Tracking the Cold..

[weatherdude]

Don:

Be sure and check out 1936 February and give me your thoughts. Coldest Feb in 116 years according to NOAA and the all time records for state low temperatures were established that month in places like Minnesota with -64F, only 18 degrees colder than this morning at International Falls. Also, ND set their state record that month in '36 with a -60F reading, and SD set their all time record low of -58 in Feb. 1936.

Interestingly, Feb 1936 was surrounded by extremely hot summers and July of 1936 ranked 116 warmest in the US of the last 116 years according to NOAA/NCDC. The preceding July, 1935, ranked 105 warmest.

Now here we are in 2011, following the 100th hottest July on the same list of ranks.

So what does this winter have in common with 1936 besides coming off a hot summer? Sun spot activity. The mid 1930s came in the end of a rather protracted solar minima, and Feb 1936 came as the world was climbing out of the min on the way to the new max. The preceding solar max prior to the 1930s was a low one compared to its predecessor, and again the last solar max back about a decade ago was down from the one before it and of course it is well known we are slowly climbing out of a protracted solar minima now

The month of Feb 1936 had anomalies of -30 to -32 degrees in the Dakotas/Minnesota area compared to the 1971-2000 normals! The summer after, the summer of 1936 not only had the hottest summer in US history with max anomalies in exactly the same areas, but it also had an extremely active hurricane season, especially in the Gulf of Mexico!

A rough year in the energy biz for sure if this is anything like it, eh?

Yours truly,

Weatherdude (lol)

[Jebman]

Don: In short - You are a genius.

EVERYTHING YOU HAVE FORECASTED THIS ENTIRE WINTER HAS COME TO PASS.

Either you're a high-end genius or you have a time machine. Or both.

Thanks for the analyses.

I would never have imagined we'd have two months in a row of consistently below normal temps.

When you talk ------- EVERYONE listens. And takes frantic notes.

[Ottawa Blizzard]

Maybe we'll get a blend of February 1934, 1971, 1993 and 2008

[Quakertown needs snow]

Another great Don post.

Thank you.

[Snow Wizard]

I hope that there are enough PNA- days so that the Pacific Northwest can experience some notable winter weather, but believe that the PNA will average positive for the month as a whole.

You say this is like a classic old time La Nina, but the fact is the NW didn't get screwed over in the old days like we are this time. Maybe this is the beginning of some nightmarish period where nothing will bring good winters to the West. This just absolutely stinks.

[Snow Wizard]

Don:

Be sure and check out 1936 February and give me your thoughts. Coldest Feb in 116 years according to NOAA and the all time records for state low temperatures were established that month in places like Minnesota with -64F, only 18 degrees colder than this morning at International Falls. Also, ND set their state record that month in '36 with a -60F reading, and SD set their all time record low of -58 in Feb. 1936.

Interestingly, Feb 1936 was surrounded by extremely hot summers and July of 1936 ranked 116 warmest in the US of the last 116 years according to NOAA/NCDC. The preceding July, 1935, ranked 105 warmest.

Now here we are in 2011, following the 100th hottest July on the same list of ranks.

So what does this winter have in common with 1936 besides coming off a hot summer? Sun spot activity. The mid 1930s came in the end of a rather protracted solar minima, and Feb 1936 came as the world was climbing out of the min on the way to the new max. The preceding solar max prior to the 1930s was a low one compared to its predecessor, and again the last solar max back about a decade ago was down from the one before it and of course it is well known we are slowly climbing out of a protracted solar minima now

The month of Feb 1936 had anomalies of -30 to -32 degrees in the Dakotas/Minnesota area compared to the 1971-2000 normals! The summer after, the summer of 1936 not only had the hottest summer in US history with max anomalies in exactly the same areas, but it also had an extremely active hurricane season, especially in the Gulf of Mexico!

A rough year in the energy biz for sure if this is anything like it, eh?

Yours truly,

Weatherdude (lol)

This won't be like February 1936 because that was actually historically cold in the NW. I'm sure it will be like that eveywhere else though.

I guess we can check La Nina and low solar off the list for bringing anything meaningful to this region.

[donsutherland1]

You say this is like a classic old time La Nina, but the fact is the NW didn't get screwed over in the old days like we are this time. Maybe this is the beginning of some nightmarish period where nothing will bring good winters to the West. This just absolutely stinks.

I wouldn't term this a "classic" La Niña. In that the Pacific Northwest has been warmer than normal, it is quite exceptional. The last moderate/strong La Niña with similar characteristics (cold east; warm Pacific Northwest) was 1903-04 (1st of three such La Niñas over a 13-winter period). 1970-71 came close. Some others i.e., 1975-76, 1999-00 were warm, on average, almost nationwide. Hence, I would be cautious about drawing conclusions that the Pacific Northwest is headed for a period during which there will be no good winters. More than likely, if the "cold in the east" La Niñas cluster over the next decade or two, almost all of them will also have colder than normal conditions in the Pacific Northwest.

[Snow Wizard]

I wouldn't term this a "classic" La Niña. In that the Pacific Northwest has been warmer than normal, it is quite exceptional. The last moderate/strong La Niña with similar characteristics (cold east; warm Pacific Northwest) was 1903-04 (1st of three such La Niñas over a 13-winter period). 1970-71 came close. Some others i.e., 1975-76, 1999-00 were warm, on average, almost nationwide. Hence, I would be cautious about drawing conclusions that the Pacific Northwest is headed for a period during which there will be no good winters. More than likely, if the "cold in the east" La Niñas cluster over the next decade or two, almost all of them will also have colder than normal conditions in the Pacific Northwest.

Yeah...I do know that the other La Ninas around the one in 1903-04 all treated us very well in spite of the cold in the East. There has been a lot of talk about the 1892-93 which was an amazingly wicked winter for the NW as well as the NE, and then 1909 and 1916 were cold pretty much everywhere.

[A-L-E-X]

Yeah...I do know that the other La Ninas around the one in 1903-04 all treated us very well in spite of the cold in the East. There has been a lot of talk about the 1892-93 which was an amazingly wicked winter for the NW as well as the NE, and then 1909 and 1916 were cold pretty much everywhere.

It's pretty crazy that this winter is so rare that the analogs we're having to use are over 100 years old! But 1872-73, 1892-93, 1903-04, 1909-10 and 1916-17 seem to be the main ones so far. What I find so puzzling is that many of those seasons also featured nice winters in the NW yet this one does not. So something must be different-- another index perhaps?

[Ellinwood]

It's pretty crazy that this winter is so rare that the analogs we're having to use are over 100 years old! But 1872-73, 1892-93, 1903-04, 1909-10 and 1916-17 seem to be the main ones so far. What I find so puzzling is that many of those seasons also featured nice winters in the NW yet this one does not. So something must be different-- another index perhaps?

The last 12 months or so have been anything but analogous (generally speaking), so to see this trend continue isn't very surprising (to me at least). At the very least, we can use the last 12 months to better understand how our atmosphere works and just how many different solutions we can anticipate.

Building the database!

[A-L-E-X]

The last 12 months or so have been anything but analogous (generally speaking), so to see this trend continue isn't very surprising (to me at least). At the very least, we can use the last 12 months to better understand how our atmosphere works and just how many different solutions we can anticipate.

Building the database!

I agree, the biggest problem we have in making comparisons to other years is that the database is just too small, so adding more can only help In such cases persistence is our best friend.

[thewxmann]

Don,

I hope you're very, very wrong about a +PNA February.

+1. I'm tired of this dry weather.

[Snow Wizard]

It's pretty crazy that this winter is so rare that the analogs we're having to use are over 100 years old! But 1872-73, 1892-93, 1903-04, 1909-10 and 1916-17 seem to be the main ones so far. What I find so puzzling is that many of those seasons also featured nice winters in the NW yet this one does not. So something must be different-- another index perhaps?

I think 1903-04 is a pretty good fit up to this point, but I am unsure how strong that Nina was.

I do believe there is another index to be discovered to help explain some of this. I can't help but wonder if the tropical Atlantic might hold some clues.

[JBG]

I hope that the OP is right, as Don Sutherland usually is. It looks like a great analysis.

[clskinsfan]

Great post. I agree with the cold air remaining in place through the winter. I hope the Mid Atlantic can get in on some of the precip though. It has been extremely dry so far this winter in the central Mid Atlantic.

[okie333]

Don: In short - You are a genius.

EVERYTHING YOU HAVE FORECASTED THIS ENTIRE WINTER HAS COME TO PASS.

Either you're a high-end genius or you have a time machine. Or both.

Thanks for the analyses.

I would never have imagined we'd have two months in a row of consistently below normal temps.

When you talk ------- EVERYONE listens. And takes frantic notes.

I said it would be near-historic blocking... as far back as last July.

[donsutherland1]

Following up on the theme of a snowy to very snowy winter for Boston and New York City, here's the data for moderate/strong La Niña cases prior to 1940. There were twelve such cases with a winter ENSO Region 3.4 anomaly of -0.75 or lower in the 1871-72 through 1939-40 timeframe. The following are the seasonal snowfall statistics for those two cities:

Boston:

Mean seasonal snowfall: 56.6"

Least: 10.0", 1875-76

Most: 96.4", 1873-74

< 40": 25% cases

50" or more: 67% cases

60" or more: 50% cases

70" or more: 25% cases

New York City:

Mean seasonal snowfall: 36.9"

Least: 18.3", 1875-76

Most: 60.3", 1872-73

< 20": 8% cases

30" or more: 67% cases

40" or more: 33% cases

50" or more: 25% cases

[Ottawa Blizzard]

Don, how's it looking for Ottawa on Wednesday? Bust?

[A-L-E-X]

Following up on the theme of a snowy to very snowy winter for Boston and New York City, here's the data for moderate/strong La Niña cases prior to 1940. There were twelve such cases with a winter ENSO Region 3.4 anomaly of -0.75 or lower in the 1871-72 through 1939-40 timeframe. The following are the seasonal snowfall statistics for those two cities:

Boston:

Mean seasonal snowfall: 56.6"

Least: 10.0", 1875-76

Most: 96.4", 1873-74

< 40": 25% cases

50" or more: 67% cases

60" or more: 50% cases

70" or more: 25% cases

New York City:

Mean seasonal snowfall: 36.9"

Least: 18.3", 1875-76

Most: 60.3", 1872-73

< 20": 8% cases

30" or more: 67% cases

40" or more: 33% cases

50" or more: 25% cases

A very illuminating post-- Don! I was wondering if you could do an end of January analysis, basically using the snowfall amounts for NYC and BOS, compare that to similar winters in the past, and make a projection on how much snowfall you expect from that point to the end of the snow season. Note I said snow season and not MET winter, as I have seen you drop hints about a snowy/cold March and perhaps even early April.