Medium Range Discussion Winter 2011-12

[CoastalWx]

Brief spike in the PNA will probably cause some troughing in the east for the first few days of January, as the vortex in AK tries to relax just a bit, but not totally go away. In fact the EC ensembles are a little cooler than normal at 850mb in the 11-15 day. However, we've been there before. With the AK vortex not totally going away the risk is probably to the warmer side..but we'll see how it goes. lately, it's been a good bet not to accept any changes to the cold side, unless it gets within 10days.

[Feb]

Brief spike in the PNA will probably cause some troughing in the east for the first few days of January, as the vortex in AK tries to relax just a bit, but not totally go away. In fact the EC ensembles are a little cooler than normal at 850mb in the 11-15 day. However, we've been there before. With the AK vortex not totally going away the risk is probably to the warmer side..but we'll see how it goes. lately, it's been a good bet not to accept any changes to the cold side, unless it gets within 10 hours

fyp

[donsutherland1]

Verification:

From #200 (12/8/2011):

The 12/8/2011 18z run of the GFS suggests that the 11-15-day period (12/19-23) could be colder than normal in the East. However, the operational GFS is not supported by the 18z GFS ensembles.

Which is more likely to be correct?

At this point, given everything that has been noted in this and the AO thread, I believe the ensembles have a better idea...

Unfortunately, it appears that the operational GFS is alone in its extended range forecast. While things could still change, my guess at this point in time is to favor an idea based on the GFS ensembles. There is a continuing risk that the area of warmth could be more expansive than shown on the GFS ensembles, especially if the EPO goes positive.

12/19-23/2011 Temperature Anomalies:

[mahk_webstah]

what a horrible north american temp map this am...aye yi yi

[usedtobe]

Don, nice verification. Some people seem to be getting excited by the euro amplitude with the strong pna on day 10. I've got my doubts as I seem to remember a couple of other attempts and the gefs ensembles don't really seem to support the idea. They are only mildly positive like they have been over the past week and it still ended up warmer than normal.

They still look bullish for a positive epo and a positive ao and nao. That's not a good combo to flood the u.s. with extreme cold like the euro does.

I guess I'm saying I still don't see any real pattern change thouugh we still may have some shots of cooler than normal air embedded in the warm stretches.

[donsutherland1]

Don, nice verification. Some people seem to be getting excited by the euro amplitude with the strong pna on day 10. I've got my doubts as I seem to remember a couple of other attempts and the gefs ensembles don't really seem to support the idea. They are only mildly positive like they have been over the past week and it still ended up warmer than normal.

They still look bullish for a positive epo and a positive ao and nao. That's not a good combo to flood the u.s. with extreme cold like the euro does.

I guess I'm saying I still don't see any real pattern change thouugh we still may have some shots of cooler than normal air embedded in the warm stretches.

I agree with you, Wes. Periodic shots of cool air (nothing really severe or prolonged) appear to be the likely outcome. But, for the most part, the warmth will probably outduel the cold. At least, for now, exceptionally warm weather does not appear too likely except perhaps when storms cut to the west.

[Ottawa Blizzard]

I agree with you, Wes. Periodic shots of cool air (nothing really severe or prolonged) appear to be the likely outcome. But, for the most part, the warmth will probably outduel the cold. At least, for now, exceptionally warm weather does not appear too likely except perhaps when storms cut to the west.

Don, when do you see a possible pattern change, if you see one at all? Late January?

By the way, I'n hoping the weather on January 4th will be good for driving. Driving to Ottawa that day, and my schedule is kind of tight!

[usedtobe]

Today's euro brings the coldest shot of the season to the east in the longer range but it looks like we still have a positive nao at 240 hrs. It will be interesting to see what its ensembles do.

[BethesdaWX]

Don, when do you see a possible pattern change, if you see one at all? Late January?

By the way, I'n hoping the weather on January 4th will be good for driving. Driving to Ottawa that day, and my schedule is kind of tight!

You'll be sick of winter by the time February rears it's ugly head

[ORH_wxman]

You'll be sick of winter by the time February rears it's ugly head

I don't see much changing between now and mid January...so even if the pattern flips in mid-January...that's at most 2 weeks of wintry weather before February comes around. That probably wouldn't be long enough to make a snow/cold lover sick of winter.

There's a possibility we go longer than that without seeing a large scale change. There needs to be a fundamental switch in the AO and we are not seeing that...certainly not for the next 10-15 days and probably a bit longer than that.

[okie333]

You'll be sick of winter by the time February rears it's ugly head

I won't be... do you think the Southern Plains will get in on the act?

[okie333]

I don't see much changing between now and mid January...so even if the pattern flips in mid-January...that's at most 2 weeks of wintry weather before February comes around. That probably wouldn't be long enough to make a snow/cold lover sick of winter.

There's a possibility we go longer than that without seeing a large scale change. There needs to be a fundamental switch in the AO and we are not seeing that...certainly not for the next 10-15 days and probably a bit longer than that.

He meant by the time February is over.

[BethesdaWX]

I don't see much changing between now and mid January...so even if the pattern flips in mid-January...that's at most 2 weeks of wintry weather before February comes around. That probably wouldn't be long enough to make a

snow/cold lover sick of winter.

There's a possibility we go longer than that without seeing a large scale change. There needs to be a fundamental switch in the AO and we are not seeing that...certainly not for the next 10-15 days and probably a bit longer than that.

I apologize I worded that terribly rushing on the IPhone. Meant to say by the time February is done with, essentially.

My winter forecast was essentially the same basic idea Roger Smith has out, with a back loaded winter following the demeanor of 2006/07.

My method of forecasting is based solely on the Sun-Earth relationship so I don't expect to be taken seriously until (hopefully) it verifies.

[Ji]

I don't see much changing between now and mid January...so even if the pattern flips in mid-January...that's at most 2 weeks of wintry weather before February comes around. That probably wouldn't be long enough to make a snow/cold lover sick of winter.

There's a possibility we go longer than that

without seeing a large scale change. There needs to be a fundamental switch in the AO and we are not seeing that...certainly not for the next 10-15 days and probably a bit longer than that.

Nobody wants to say it but I will...there is now a good chance that the pattern never flips as the Nina gets stronger. Could be a shutout till next winter for i95

[BethesdaWX]

Nobody wants to say it but I will...there is now a good chance that the pattern never flips as the Nina gets stronger. Could be a shutout till next winter for i95

Famous last words.

[ORH_wxman]

Nobody wants to say it but I will...there is now a good chance that the pattern never flips as the Nina gets stronger. Could be a shutout till next winter for i95

Its certainly possible we see the AO stay mostly positive for the rest of the winter. I do not know what will happen later in January or February but I strongly doubt we see a shift over the next 2-3 weeks.

Hopefully the MJO can lend a helping hand to shuffle the deck a bit, but it looks like it won't be strong enough to help out for the next 2 weeks. Hopefully that is wrong though.

[donsutherland1]

Nobody wants to say it but I will...there is now a good chance that the pattern never flips as the Nina gets stronger. Could be a shutout till next winter for i95

12z ECMWF spikes the PNA for a brief time coinciding with a brief but fairly sharp shot of cold. But is it right? Probably not, but a short-duration cold shot is likely for a few days during the first week in January. Also, for the month as a whole, I don't believe January will be as warm relative to normal as December. It will probably be the warmest January since 2008 or perhaps 2007, but probably won't rival January 2006.

[CoastalWx]

I don't see much changing between now and mid January...so even if the pattern flips in mid-January...that's at most 2 weeks of wintry weather before February comes around. That probably wouldn't be long enough to make a snow/cold lover sick of winter.

There's a possibility we go longer than that without seeing a large scale change. There needs to be a fundamental switch in the AO and we are not seeing that...certainly not for the next 10-15 days and probably a bit longer than that.

I'm thinking the AO averages positive right through the month of January. Maybe we can get a transient ridge or two...but we'll see I suppose.

[donsutherland1]

I'm thinking the AO averages positive right through the month of January. Maybe we can get a transient ridge or two...but we'll see I suppose.

I agree. For now, I see little that will change the generally predominant AO+ pattern. No SSWs appear imminent. Other large-scale hemispheric pattern changes don't yet appear imminent.

[CoastalWx]

I agree. For now, I see little that will change the generally predominant AO+ pattern. No SSWs appear imminent. Other large-scale hemispheric pattern changes don't yet appear imminent.

I think that elongated vortex is getting kicked in the groin by ridges over by western Russia and from western NAMR. There are signs that the AK vortex tries to appear once again in the euro ensembles in the longer range too, but we'll see how that goes. Still a very + NAO look, but hopefully the ridging in western Russia can compress the PV a little to the south.

[donsutherland1]

I think that elongated vortex is getting kicked in the groin by ridges over by western Russia and from western NAMR. There are signs that the AK vortex tries to appear once again in the euro ensembles in the longer range too, but we'll see how that goes. Still a very + NAO look, but hopefully the ridging in western Russia can compress the PV a little to the south.

I agree and certainly hope that the PV can be compressed a little to the south.

[Cheeznado]

Holy S%^&$ the differences in the models from 96 hours on are so massive it is comical. The New Euro and CMC have the trough incredibly farther west than the GFS and UKMET, the GFS ensembles show little spread, this one is quite a puzzle. The folks doing the 7 day forecasts this week will be earning their money (or not).

[usedtobe]

Holy S%^&$ the differences in the models from 96 hours on are so massive it is comical. The New Euro and CMC have the trough incredibly farther west than the GFS and UKMET, the GFS ensembles show little spread, this one is quite a puzzle. The folks doing the 7 day forecasts this week will be earning their money (or not).

I know, the ukmet is the second best model in the world and the euro is the best. The lack of spread in the gefs ensembles is very troublesome.

[JoMo]

This is the 5th run or so the Euro has had the trough in the middle of the nation. 12z GGEM looks more like the Euro after it backed off and sided more with the GFS last night.

[Ji]

With the Eastern U.S. experiencing yet another exceptionally balmy December day, the desire for a pattern change that would reintroduce winter to a winter-starved region is only growing stronger. Unfortunately, the tyranny of an AO+/EPO+ setup will likely continue to deny starving snow geese of their wish. Down the road, 2012 will likely begin as 2011 ends, with more unseasonable warmth in the East. In fact, prospects for near coast-to-coast warm anomalies for the first week in December continue to grow.

Below is a chart that shows the current 11-15 day forecast on the 12/21 18z run of the GFS, the NAEFS forecast anomalies for the 12/29-1/4 period, and analogs constructed from the likely state of the major teleconnection indices for La Niña events. The composite temperature anomalies are based on an AO in the +1 to +3 rangem PNA in the -0.50 to +0.50 range, and ENSO R3.4 anomalies in the -1.50 to -0.75 range for the 1/1-10 timeframe (1950-2011)

There is strong agreement among all three maps.

At present, the areas that have the best chance at seeing some cool anomalies are the Southwest and also Pacific Northwest. The rest of the U.S. and southern Canada will likely experience warmer than normal temperatures for the overall January 1-7, 2012 timeframe. Cold shots will likely be transient and modest. No significant Arctic outbreaks are likely.

Until one sees evidence of a regime change in the major teleconnection indices, one should be wary of modeled pattern changes. False signals have abounded this month. Instead, the sea of warmth has remained essentially unbroken in the East with only a few days of cool anomalies thrown in. Winter has resided in the Plains States and also Pacific Northwest.

are you still thinking blowtorch Jan 1-7 Don?

[donsutherland1]

are you still thinking blowtorch Jan 1-7 Don?

Ji,

I was thinking of unseasonable warmth/milder than normal, but not an all-out early January 2007-type blowtorch. I still suspect that the GFS might be too cold, though it is possible that the Southeast could be somewhat cooler than normal.The GFS is counting on a PNA spike. Upcoming model runs will be helpful. However, even if the week does turn out cooler than normal on average, that does not necessarily mean that the cold would lock in. I highly doubt that it will lock in right now given the general EPO+/AO+ pattern.

[HM]

Ji,

I was thinking of milder than normal, not an all-out 2007-type blowtorch. I still suspect that the GFS might be too cold, though it is possible that the Southeast could be somewhat cooler than normal.The GFS is counting on a PNA spike. Upcoming model runs will be helpful. However, even if the week does turn out cooler than normal on average, that does not necessarily mean that the cold would lock in. I highly doubt that it will lock in right now given the general EPO+/AO+ pattern.

The ECMWF / ensembles are pretty cold over the East and probably would verify colder than if the GFS solution were to work out. Really, both models agree on a PNA spike but it appears the 18z GFS wants to delay the high amplification a few days.

The PNA spike has support from the GWO.

[winterymix]

are you still thinking blowtorch Jan 1-7 Don?

The 18Z GFS is historically wild for January 8th.

[donsutherland1]

A quick note:

My initial idea of a mild first week of January could be incorrect. The ensembles have come into good agreement about a PNA+ rise in early January (numbers using the old PNA valuations are very high on some of the guidance). The PNA typically has a higher correlation than the AO in January, though extreme AO-/AO+ events can overwhelm the impact of the PNA. A PNA+, especially at modeled levels, has typically resulted in cool anomalies in the East/warm anomalies in the West. The consistency on the modeling has led me to believe that the PNA signal is not a false alarm. I'll post a map showing the anomalies with a PNA in the +0.5 to +1.5 range (new values) tonight.

The longer-range idea of a milder than normal January in the East/cooler than normal January in parts of the West (Pac NW and Southwest) perhaps the warmest since January 2008 (not the extreme January 2006) in the East remains unchanged. I still don't see enough of a pattern change that would lock in the cold in the East. Therefore, even as I continue to suspect that January could have the closest anomalies to normal in the East of any of the winter months based on insight from 1975-76 and 1999-00 teleconnection developments e.g., AO+ regimes, I do believe the East will wind up on the mild side of normal.

Finally, the lack of December snowfall in the Mid-Atlantic and southern New England areas raises my confidence in the idea that seasonal snowfall in that region will come out below to perhaps much below normal. Given the predominance of the AO+, I still believe odds are strongly against a KU-type snowstorm this winter. A "Near Miss" with heavier interior snows + a moderate (probably changeover case) will probably be more likely.

[mitchnick]

A quick note:

My initial idea of a mild first week of January could be incorrect. The ensembles have come into good agreement about a PNA+ rise in early January (numbers using the old PNA valuations are very high on some of the guidance). The PNA typically has a higher correlation than the AO in January, though extreme AO-/AO+ events can overwhelm the impact of the PNA. A PNA+, especially at modeled levels, has typically resulted in cool anomalies in the East/warm anomalies in the West. The consistency on the modeling has led me to believe that the PNA signal is not a false alarm. I'll post a map showing the anomalies with a PNA in the +0.5 to +1.5 range (new values) tonight.

The longer-range idea of a milder than normal January in the East/cooler than normal January in parts of the West (Pac NW and Southwest) perhaps the warmest since January 2008 (not the extreme January 2006) in the East remains unchanged. I still don't see enough of a pattern change that would lock in the cold in the East. Therefore, even as I continue to suspect that January could have the closest anomalies to normal in the East of any of the winter months based on insight from 1975-76 and 1999-00 teleconnection developments e.g., AO+ regimes, I do believe the East will wind up on the mild side of normal.

Finally, the lack of December snowfall in the Mid-Atlantic and southern New England areas raises my confidence in the idea that seasonal snowfall in that region will come out below to perhaps much below normal. Given the predominance of the AO+, I still believe odds are strongly against a KU-type snowstorm this winter. A "Near Miss" with heavier interior snows + a moderate (probably changeover case) will probably be more likely.

wx forecasting remains a humbling experience

all the models seemed locked on the warmth during the 1st week of JAN and they now look to bust

that's why, imho, there's still hope this winter

harder to come by will be the snow; hopefully, that will follow in mid-late JAN if not sooner