Medium Range Discussion Winter 2011-12

[wxmx]

First signs of La Niña loosing it's grip? West vs East ENSO regions, who will get the upper hand this spring?

[easternsnowman]

think March will be okay I believe Don mentioned the 1956 analog.

[Snowstorms]

First signs of La Niña loosing it's grip? West vs East ENSO regions, who will get the upper hand this spring?

Yes that is quite the battle. Subsurface anomalies across the far Western Nina regions arent as cold and haven't really been all that cold since this Nina began. The -PDO anomaly has also weakened since last Fall but still continues to be quite widespread and still well below normal. This warming observed across the Eastern regions seems to be in relation to the MJO wave. It will be interesting to see how the MJO progresses thru March and for much Spring. Could we see a rapid weakening like last year or could it strengthen later in Spring towards Summer and become a decently sized Nina once again similar to that of the 73-76 Nina regime? It remains to be seen.

Any thoughts on how this may progress thru Spring in your opinion?

[JoMo]

Someone could start a Long Range discussion thread?

[donsutherland1]

think March will be okay I believe Don mentioned the 1956 analog.

1956 is still in the mix. It has faded somewhat, but it is too soon--at least for me--to make a guess at March. I'll do so some time after February 20. The evolution of the La Niña will be a key driver. Whether or not blocking is likely will be another. The rapid progression of the MJO into Phase 3 (Canadian and ECMWF ensembles) in late February is somewhat troubling for a cold outcome. But all of that is still relatively far into the future and things could change.

[uncle W]

1956 is still in the mix. It has faded somewhat, but it is too soon--at least for me--to make a guess at March. I'll do so some time after February 20. The evolution of the La Niña will be a key driver. Whether or not blocking is likely will be another. The rapid progression of the MJO into Phase 3 (Canadian and ECMWF ensembles) in late February is somewhat troubling for a cold outcome. But all of that is still relatively far into the future and things could change.

March 1956 is not a great analog...That year started very cold but moderated in February...March and the rest of the spring was cool...The AO averaged negative from November to February...I think 1974-75 is a better analog...enso and AO are better matches also...Dec-Feb was mild and March was cold...

[Amped]

I have also noticed the Stratospheric PV has been centered between Greenland and Norway nost of the winter. This maybe aiding to reduce our blocking potential.

[wxnut]

February 23-29, 2012 Thoughts...

.....

Finally, the MJO is racing through Phase 8. By the start of March, some of the guidance suggests it could be well through Phase 2. If so, there is a growing risk that the MJO could spend much of the month in the phases that predominated during December, January, and early February, as its rate of progression will very likely decelerate at some point. The CFSv2 is quite aggressive with the forecast warmth for March. Warmer analogs, including 1974, 1985 and 2000 are increasing in the mix of possible candidates for March. All said, the probability of a mild or warm March in many areas that experienced an unseasonably warm winter is probably rising. Things can still change over the next few weeks, so it's too soon for me to be certain of the outcome. The evolution of the La Niña will likely play a key role in shaping the March outcome.

With continued warmth in February and the extraordinary lack of snowcover over the northern Plains and Canadian Prairies, this would certainly support the growing probability of an early spring (such as 2000) (Bismarck, ND has had only 5.9" of snow all winter.. crazy.) Unless we get a pattern change soon that will bring widepsread snowcover through the central continent, increasing solar strength and modifying airmasses will be limiting the severity of cold outbreaks from central Canada and US.

[Nic]

With continued warmth in February and the extraordinary lack of snowcover over the northern Plains and Canadian Prairies, this would certainly support the growing probability of an early spring (such as 2000) (Bismarck, ND has had only 5.9" of snow all winter.. crazy.) Unless we get a pattern change soon that will bring widepsread snowcover through the central continent, increasing solar strength and modifying airmasses will be limiting the severity of cold outbreaks from central Canada and US.

Not really there will likely be a major freeze if it warms up to early and things begin to grow, not really spring in the sense of the start of the growing season, since they still have to plant at the same time because of freeze threats. More like a false spring.

[Geos]

Not really there will likely be a major freeze if it warms up to early and things begin to grow, not really spring in the sense of the start of the growing season, since they still have to plant at the same time because of freeze threats. More like a false spring.

Yeah planting too early could come at a severe cost. If we get a false spring say in early March and then a cold snap for a spell. That could adversely affect other plants that may be budding.

There has been some really late frosts in the last decade in this region. As late as June 1st! And those frosts/freezes have set back the growing season. Typically late frosts lead to a cool, wet summer.

[iu2001grad]

Not really there will likely be a major freeze if it warms up to early and things begin to grow, not really spring in the sense of the start of the growing season, since they still have to plant at the same time because of freeze threats. More like a false spring.

I rarely post and correct me if I am wrong..but i don't think the poster you were responding to was talking about the actual growing season, but rather the increase (or growing) chance of an early spring...

[wxnut]

I rarely post and correct me if I am wrong..but i don't think the poster you were responding to was talking about the actual growing season, but rather the increase (or growing) chance of an early spring...

That's correct. By "early spring", I was referring to the liklihood of above normal temperatures and below normal snowfall in March which would give the impression that winter ended prematurely. But of course, even with an early spring, you can still get cold outbreaks and snow in April or even May that can cause serious damage to early budding plants.

[donsutherland1]

Some morning thoughts...

1. The La Niña of Winter 2011-12 may have peaked. The SOI is going negative more frequently now. The ENSO Region 3.4 cool anomalies have warmed somewhat in the most recent week. Ensemble guidance and climatology both argue for the La Niña to continue to weaken during the coming weeks.

SOI: Percentage of Days < 0

December 2011: 3%

January 2012: 26%

February 2012: 50%

ENSO Region 3.4 Anomalies:

December 2011: -1.04°C

January 2012: -1.08°C

Week Centered Around:

January 18: -1.1°C

January 25: -1.1°C

February 1: -1.2°C (Possible Peak?)

February 8: -1.0°C

2. The Arctic Oscillation has gone positive in recent days:

February 11: -0.394

February 12: +0.179

February 13: +0.190

3. Historic climatology associated with La Niña winters argues against a KU-type snowstorm this coming weekend. Since 1950, when daily recordkeeping concerning the AO commenced, there has been only one KU snowstorm during La Niña conditions with an AO > 0: the January 24-26, 2000 storm. A more localized snow event cannot be ruled out, but such an outcome is not assured.

4. Recent developments concerning the La Niña and AO have increased the probability of a mild March in the East. Should the PNA go negative as forecast by the ensembles, some of which try to tank it, the probability of a cold outcome in some part of the West would be enhanced.

[Rainshadow]

Some morning thoughts...

1. The La Niña of Winter 2011-12 may have peaked. The SOI is going negative more frequently now. The ENSO Region 3.4 cool anomalies have warmed somewhat in the most recent week. Ensemble guidance and climatology both argue for the La Niña to continue to weaken during the coming weeks.

SOI: Percentage of Days < 0

December 2011: 3%

January 2012: 26%

February 2012: 50%

ENSO Region 3.4 Anomalies:

December 2011: -1.04°C

January 2012: -1.08°C

Week Centered Around:

January 18: -1.1°C

January 25: -1.1°C

February 1: -1.2°C (Possible Peak?)

February 8: -1.0°C

2. The Arctic Oscillation has gone positive in recent days:

February 11: -0.394

February 12: +0.179

February 13: +0.190

3. Historic climatology associated with La Niña winters argues against a KU-type snowstorm this coming weekend. Since 1950, when daily recordkeeping concerning the AO commenced, there has been only one KU snowstorm during La Niña conditions with an AO > 0: the January 24-26, 2000 storm. A more localized snow event cannot be ruled out, but such an outcome is not assured.

4. Recent developments concerning the La Niña and AO have increased the probability of a mild March in the East. Should the PNA go negative as forecast by the ensembles, some of which try to tank it, the probability of a cold outcome in some part of the West would be enhanced.

Don,

This has not been a quality winter, but this thread (and yours among others posts in it) have been on the level of several KU events.

[easternsnowman]

I remember hearing a little while ago if the nina weakened it would be a cold March.

[GaWx]

Some morning thoughts...

1. The La Niña of Winter 2011-12 may have peaked. The SOI is going negative more frequently now. The ENSO Region 3.4 cool anomalies have warmed somewhat in the most recent week. Ensemble guidance and climatology both argue for the La Niña to continue to weaken during the coming weeks.

ENSO Region 3.4 Anomalies:

December 2011: -1.04°C

January 2012: -1.08°C

Week Centered Around:

January 18: -1.1°C

January 25: -1.1°C

February 1: -1.2°C (Possible Peak?)

February 8: -1.0°C

Assuming the weekly peak will end up being that -1.2 C of the 2/1 week, which seems pretty likely, the odds favor that the DJF trimonth will come in at -1.0 C and be the Nina trimonthly peak. Based on definitions I use, that would make the current Nina's peak weak for historical purposes (upper end similar to 1950-1) since I define weak as no colder than -1.0 trimonthly peak anomaly.

[wxmx]

I remember hearing a little while ago if the nina weakened it would be a cold March.

It always weakens come March...the rate of weakening is more important.

[GaWx]

Don and others,

This is a reminder the GEFS underwent sig. changes, including model physics, starting with the 12Z run today (2/14). That could possibly mean tomorrow morning's 2/15 0Z based NAO/AO/PNA predictions will be a good bit different from today's 2/14 0Z based predictions just from the major model mod.

[donsutherland1]

Don and others,

This is a reminder the GEFS underwent sig. changes, including model physics, starting with the 12Z run today (2/14). That could possibly mean tomorrow morning's 2/15 0Z based NAO/AO/PNA predictions could be a good bit different from today's 2/14 0Z based predictions just from the major model mod.

Thanks GaWx.

I'm aware of that. I don't believe CPC put out the ensemble spread this morning, perhaps on account of the transition to the changes you cited.

[donsutherland1]

Don,

This has not been a quality winter, but this thread (and yours among others posts in it) have been on the level of several KU events.

Many thanks, Tony.

[donsutherland1]

I remember hearing a little while ago if the nina weakened it would be a cold March.

The evolution of the ENSO reflects not just the direction of the change taking place, but also the overall state, rate of change, stability in ENSO conditions, etc. Furthemore, ENSO is not the sole factor involved when one tries to look ahead to the following month.

Currently, about 60% of the analog candidates based on my preliminary review now feature milder conditions in the East. The share showing a cold outcome in a portion of the West is comparable. Factoring in the observed decadal temperature change for March, the possibility of cold in parts of the West is perhaps higher than what the current sample shows. Prospects for cold across a part of Eastern Europe are also showing up, even in areas where there has been observed decadal warming. Nothing is cast in stone, but the trend in possible analog candidates is noted. I don't like the trend, dislike the non-winter we've had, but try to be as objective as I can be when looking ahead. I'll probably post my March guess in 8-10 days.

For some other "opinions," the latest CFSv2 forecast shows fairly widespread warmth in the East. The composite for the years showing up in the 11-day objective analogs (some cold, some warm) yield warmth across much of the East, except for New England.

Finally, a warm monthly anomaly does not mean that there cannot be variability e.g., some cold even wintry periods. The seasonal transition can feature a lot of variability.

[easternsnowman]

The evolution of the ENSO reflects not just the direction of the change taking place, but also the overall state, rate of change, stability in ENSO conditions, etc. Furthemore, ENSO is not the sole factor involved when one tries to look ahead to the following month.

Currently, about 60% of the analog candidates based on my preliminary review now feature milder conditions in the East. The share showing a cold outcome in a portion of the West is comparable. Factoring in the observed decadal temperature change for March, the possibility of cold in parts of the West is perhaps higher than what the current sample shows. Prospects for cold across a part of Eastern Europe are also showing up, even in areas where there has been observed decadal warming. Nothing is cast in stone, but the trend in possible analog candidates is noted. I don't like the trend, dislike the non-winter we've had, but try to be as objective as I can be when looking ahead. I'll probably post my March guess in 8-10 days.

For some other "opinions," the latest CFSv2 forecast shows fairly widespread warmth in the East. The composite for the years showing up in the 11-day objective analogs (some cold, some warm) yield warmth across much of the East, except for New England.

Finally, a warm monthly anomaly does not mean that there cannot be variability e.g., some cold even wintry periods. The seasonal transition can feature a lot of variability.

It seems like the trend since March 2010 has been for monthly departures to average 2 to 3 above normal in aboout 20 of those months, like I said before this trend cannot be ignored and if one were to forecast that he will be right over 80% of the time.

[easternsnowman]

NYC is just one example of how the warmth has been really winning out.

I think all of the big cities from DC to Boston have experienced similar conditions It is not so pronounced in the burbs of the cities. We are getting to the point in many instances where the burbs are 10 to 15 degrees lower than the urban heat islands.

[wxmx]

It seems like the trend since March 2010 has been for monthly departures to average 2 to 3 above normal in aboout 20 of those months, like I said before this trend cannot be ignored and if one were to forecast that he will be right over 80% of the time.

It's easy to say in hindsight...why not go with last 10 years, or last 10 days?

[am19psu]

Guys, climate change stuff belongs in the climate change forum unless it specifically pertains to the medium range forecast

[donsutherland1]

It seems like the trend since March 2010 has been for monthly departures to average 2 to 3 above normal in aboout 20 of those months, like I said before this trend cannot be ignored and if one were to forecast that he will be right over 80% of the time.

When one is forecasting for the short and medium-term, expected synoptic patterns, are the predominant driver of the outcome. One cannot automatically broadbrush every region as having the anomaly shown in that area's long-term trend, even when the trend is taken into consideration.

When one reviews the medium-term outcomes, one finds:

1. Cool and warm anomalies are not locked in place.

2. There is no uniformity in the anomalies.

3. They are not identical to longer-term trends. There is a lot of variability.

The below diagram for December (1981-10 vs. 1971-00 base period, 2010, and 2011) illustrates my point. In this case, I used monthly outcomes (there's even more variability in shorter-term ones).

[Ottawa Blizzard]

Don, what did you think of the 18z run of the GFS? Went crazy with the cold after the 26th.

[donsutherland1]

Don, what did you think of the 18z run of the GFS? Went crazy with the cold after the 26th.

Given some of the differences from the ensembles, I suspect that it's overdone on the cold.

[GaWx]

Given some of the differences from the ensembles, I suspect that it's overdone on the cold.

Folks,

****Fwiw warning**** Wow, major E cold wave 2/27-9 if the 0Z GFS were to just happen to be close to accurate. Those suffering from a lack of cold this winter are going to salivate over these maps. By the way, that's four runs in a row of a cold 11-15 in the northcentral U.S. Could this be due to a cold bias or is this the real deal? Stay tuned to this BB for further updates as they become available.

[Ji]

Folks,

****Fwiw warning**** Wow, major E cold wave 2/27-9 if the 0Z GFS were to just happen to be close to accurate. Those suffering from a lack of cold this winter are going to salivate over these maps. By the way, that's four runs in a row of a cold 11-15 in the northcentral U.S. Could this be due to a cold bias or is this the real deal? Stay tuned to this BB for further updates as they become available.

Jb says severe cold coming late feb. sorry don