Where is our "pattern change" ?

[earthlight]

There is no reason to start this post with anything other than the three words which you will hear least out of most forecasters in the professional field: I was wrong. No sugar coating, no half-way statements, no "what if"s or "maybe if"'s. I was wrong with most of my forecasts beginning in October and moving forward through early to mid December as well. There are several things which have gone wrong (even with the most recent forecast for a late-January flip to cold/snowy) which will be covered in this post. But the fact of the matter is...the change in the hemispheric pattern that myself, and many other forecasters including professional meteorologists were expecting..has not happened at all.

To this point, this winter has been unique in more than one sense. Plenty of people on these forums and throughout the community have extended their reach and shown knowledge of different atmospheric processes...stratospheric warming talk almost became a social trend in our community for example. But things have become way too complicated and people are looking in the wrong places for the right things. For example you will not find high latitude blocking on a GEFS NAO graph. You will not find accurate medium range pattern predictions through the GFS or Euro AO or NAO forecasts. In fact...the GFS has been particularly bad in forecasting these things at a relatively moderate lead.

The image below shows the GFS AO forecasts...for each 4 runs throughout the day...and the observed value. will put it to you this way...this is an absolutely horrendous display of model skill. And while this graph doesn't necessarily dictate the actual "skill" of the model...what it should tell you is that we have seen 3 or more false starts to this pattern change...in AO forecasts alone.

There are still several forecasters who are still pushing talk about a pattern change occurring when in fact the "pattern change" has already occurred...but the hemispheric change to one more favorable for snow and cold in the east has not.

To this point -- the general talk about a "pattern change" in the meteorological community is becoming absolutely incessant and, to be honest, quite misinterpreted. The misinterpretation lies in the specific forecasters definition of a "pattern change" and the public perception of it as well. If you talk to someone in the Pacific NW they will tell you, you're damn right the pattern has changed in the last 20 days. But for the majority of posters here..the pattern has not changed to be more favorable for what they want which is cold and snow. This is where the problem arises...forecasters are not differentiating between a pattern change and a hemispheric/pattern change which is favorable for cold/snow in the east.

These are the newest GEFS ensemble mean height anomalies at 84 hours. This is fairly current and the skill at this time is moderately accurate. If you can look at that map and say that the pattern has not changed from December until now...you either need to clear your cache or need to take a better look. However...this does not mean that the "new" pattern is favorable for our area. There is still a very anomalous Alaskan Vortex in place. That's the first thing that jumps out at me because if you want winter weather on the east coast it is one of the worst things you could see. Also notice the high latitude ridging...it is on the wrong side of the pole for our area at the present time...but it is there and it is quite anomalous in it's own respect. Finally...and this is an interesting point to drive home...there is a large trough/negative height anomalies associated with an upper level low over the Pacific. A friend of mine Dave Tolleris made a terrific post about a week ago about the importance of a large 500mb trough or upper level low in the Sea of Japan as it was modeled by the ECMWF ensembles at that time. Such a development teleconnects very well with not only the development of a more favorable Pacific...but processes to drive the Polar Vortex and associated air towards Eastern Canada in a very favorable position for us. The label on the above image reads "Too far east"...because not only is it too far east..but it never developed in the Sea of Japan at all...effectively canning the favorable changes which the Euro ensemble mean were hinting at. The next image shows the results.

We are now moved forward past 180 hours and the end result of the hemispheric ongoing changes is fairly obvious. Not only has the high latitude ridging maintained itself over Russia...but the vortex over Alaska remains in place and has become more anomalous. This is the GEFS showing the Polar Vortex becoming well established over the Pacific end of the Arctic. There is nothing remotely favorable about this development. You can also see the "channel" of arctic/polar air which takes the Arctic air from the Pacific through Central Canada and right over Baffin Island into Greenland (also known as + NAO).

In this pattern the amplification of the PNA or a ridge out west becomes our only chance for trough amplification in the east which could possibly make things favorable for snow. You'll notice on the 180 hr image above that the minute the west coast US ridge becomes less amplified..the Southeast Ridge on the East Coast rises and we see an area of positive height anomalies emerge. These are the facts. These are things that we cannot deny -- it is the hemispheric pattern which is developing in front of us. However as weather enthusiasts and in some cases professionals we are left to ask ourselves a question we've asked in our own heads thousands of times in various situations. If it's broken, will it get fixed? Where can we start and what needs to happen?

The answer, really...is that we need to see the movement of the Polar Vortex from the Pacific side of the Arctic Circle towards Canada and into a more favorable position. Yes...we could use some high latitude blocking. But the ensemble forecasts are very consistent in developing this vortex over Alaska and the Pacific side..which is no doubt the first thing that needs to change. The MJO does not look very favorable on most ensemble guidance with decent agreement on the impacts of Phase 6 (see the h5 and 2m temp anomalies for that phase...more of the same). That being said...the MJO forecasts have been incredibly inconsistent this season as well which brings a tremendous lack of certainty to their forecasts.

Synoptically, we can look for amplification on the Pacific side as a saving grace in the mean time. Any Greenland or Davis Straight blocking that has been forecast to develop on all medium range guidance has not developed at all....and at this point I would not be banking on it to develop any time soon. The development of +PNA in the longer term could certainly support the potential for a storm...so long as the NAO region has not completely broken down into another +NAO state. The way it is now..and the way it is forecast to be through the term...is generally neutral...which could give the PNA some extra drive in the pattern.

For example, there may be the potential for trough amplification in the east on Super Bowl weekend. Most ideas haven't worked out so far this meteorological winter when trying to analyze pattern specifics in the medium range...but we are beginning to see most ensemble means indicate a favorably positioned +PNA with a ridge axis near Boise.

----- However..until things change on the Pacific side with the positioning of the vortex over Alaska and the Pac side of the Arctic Circle...or until we see a decently established -NAO block...nothing will change with the pattern we experience here. We will continue to see above normal temperature departures on average...with brief shots of below normal cold air bookended by warmth.

Before ending the post...I think it is important for me to break it down for a second and stop any confusion before it can even begin. This post was not meant to call for the end of winter...it was not meant to say that we won't see any more snow. What it was meant to do was summarize the past few weeks and look ahead to the near future..and make a point as to how the pattern has not cooperated until now and doesn't look to be doing so through the medium range either. All of this said...if you're looking for cold/snow...keep your head up. Things can change -- and although it doesn't look to be coming immediately, we still have just shy of two months of winter left to go.

[Met1985]

Great right up. Things have not looked good for a while and still do not but like you said we still have a ways to go.

[atownwxwatcher]

Could not agree more with everything you just said!

[Weathergun]

Great essay, John!

We just can't seem to get rid of AK vortex this winter, for any long period of time. As long it keeps reasserting itself, we won't see a sustained cold and stormy pattern in the East Coast. That doesn't mean there won't be any snow. But we'll be very much threading the needle. I also won't believe any blocking the models or ensembles show beyond 144hrs. Even they show some consistency. As you said, too many false signals this year.

Btw, I don't believe the +PNA showing up on the ensemebles will be help us much in early Feb. The PV over Alaska and Sibera regions, is going to lock up cold air in those regions. If you look at the 0z GEFS 2m temp anomalies below, we are still running above normal, through day 14. Ironically, we got a first appreciable snow this winter, when the PNA was negative.

http://www.meteo.psu...2_0z/tloop.html

[ORH_wxman]

Good writeup.

The pattern did change for about a 7-10 day period...that is when most northeast stations produced negative departures from Jan 14-22 and the one snow event on Jan 21 (multiple snow events in New England)....the biggest failure of the pattern change was the inability for the EPO block to hold...it retrograded pretty far west as soon as it formed. The NAO never really looked very promising during this period so I didn't think the snow chances were all that great looking for the M.A., coastalwx and I described the pattern as "it gives us a chance" and that was for NE...it was "the PAC changes first" type of pattern....there was hope this change in the PAC would hold while we wait for a -NAO, but it never really happened.

The PAC looks to change to more favorable again as we go into early February, but the NAO still doesn't look all that great but at least it doesn't look as bad as it did before. The NAO is pretty important if you want large snowstorms in the M.A. You can get smaller ro moderate events without it, but in order to repeat the type of KU craziness of the past 2 winters, the NAO really need to be there...otherwise you are hoping for a perfectly timed setup which as many of us know, usually doesn't happen.

[rgwp96]

It's plain and simple, the weather will do what it wants reguardless of all those pretty graphics(not trying to be a ahole). Longe range forecasting will never be accurate, flip a coin and you will have the same chance of getting it right.

[SnowGoose69]

It's plain and simple, the weather will do what it wants reguardless of all those pretty graphics(not trying to be a ahole). Longe range forecasting will never be accurate, flip a coin and you will have the same chance of getting it right.

Believe me, this winter was somewhat catchable in its poorness when you look back now. So many indices popping similar to years like 1999-00 and other poor ones but alot of people got all caught up in the deal that because of the changed PDO phase and recent apparent NAO phase change we could not see a 1999-00. The thing is the NAO can have raging + and - years within the dominant opposing phase cycle all the time and generally La Ninas are bad for the NE U.S., especially the coast, all that considered too many people were going cold this year. I would tend to agree with some of the meteorologists that perhaps the insanely cold stratosphere in November could have ultimately caused the entire thing to go bad because it ultimately forced snow pack into areas we don't generally want to see it going too and set the whole negative feedback mechanism into full blown effect.

[easternsnowman]

It's plain and simple, the weather will do what it wants reguardless of all those pretty graphics(not trying to be a ahole). Longe range forecasting will never be accurate, flip a coin and you will have the same chance of getting it right.

I agree you might as well check the Farmers almanac they're just as good if not better than the computers and long range forecasters.

[donsutherland1]

Very nice summary of what has happened. The forecasted vs. actual values on the major teleconnection indices have revealed less skillful forecasts than desirable. I suspect that the La Niña has had a role in that.

IMO, if one recalls some of the MJO forecast diagrams, those forecasts have been even worse. If one looks back at the MJO, one finds that it has been quite "sticky" in the "warm" phases (for the East). December saw the MJO in Phase 4 or 5 94% of the time. Through 1/23, the MJO has been in Phase 6 70% of the time. Until there is evidence that the persistence of the MJO to lock into one or two predominant phases is breaking down, I'd be cautious about assuming a progression anytime soon into some of the colder phases, regardless of what the ensembles might be suggesting.

Finally, on the brighter side, the persistent AO+ regime has been decaying. Negative readings are occurring more frequently and the AO recently fell to its lowest level in just over a year.

[donsutherland1]

I agree you might as well check the Farmers almanac they're just as good if not better than the computers and long range forecasters.

At your suggestion, I just did.

Here's the forecast for the Mid-Atlantic for January 2012 and the overall February temperature anomaly from The Old Farmer's Almanac:

JANUARY 2012: temperature 38° (5° above avg.); precipitation 2.5" (1" below avg.); Jan 1-6: Rain, then sunny, mild; Jan 7-11: Showers, then sunny, seasonable; Jan 12-19: Snow, then sunny, warm; Jan 20-24: Rain to snow, then sunny, cold; Jan 25-29: Rain and snow north; sunny, mild south; Jan 30-31: Blizzard.

FEBRUARY 2012: temperature 28° (5° below avg.)

[Redmorninglight]

Fantastic read and painfully honest. One thing I heard this morning was how natural gas prices are super low and how this mild winter across most of the ConUS has kept it that way. I am sure Alaskans would love to send some of that cold our way as it has been brutal there since November. Thanks for all you have contributed.

[bates]

At your suggestion, I just did.

Here's the forecast for the Mid-Atlantic for January 2012 and the overall February temperature anomaly from The Old Farmer's Almanac:

JANUARY 2012: temperature 38° (5° above avg.); precipitation 2.5" (1" below avg.); Jan 1-6: Rain, then sunny, mild; Jan 7-11: Showers, then sunny, seasonable; Jan 12-19: Snow, then sunny, warm; Jan 20-24: Rain to snow, then sunny, cold; Jan 25-29: Rain and snow north; sunny, mild south; Jan 30-31: Blizzard.

FEBRUARY 2012: temperature 28° (5° below avg.)

Also depends on which Farmer's Almanac. You chose the most widely known but there are many. This benefits all of them as their outlooks differ from each other and cover all possibilities. Therefore, inevitably someone will say "hey, the Farmer's Almanac nailed last year's winter", but that will likely be based on the one that got it right out of the many that got it wrong. Happens year in and year out.

[mahk_webstah]

I agree you might as well check the Farmers almanac they're just as good if not better than the computers and long range forecasters.

He's a modest guy, but Don has been fantastic this year and last with the overall picture. Don if I remember correctly your only "fail" was in thinking the strong blocking would return late last winter? I would take Don and most of the mets on here before the Farmer's Almanac any day....but that Jan call isn't bad lol. And there does look to be a deepening trough off the east coast on Monday Jan 30 according to HPC.

Oh and John, thank you for a great, readable and understandable write-up. As a non-met I really appreciate all that you and the other guys put into this board.

[easternsnowman]

At your suggestion, I just did.

Here's the forecast for the Mid-Atlantic for January 2012 and the overall February temperature anomaly from The Old Farmer's Almanac:

JANUARY 2012: temperature 38° (5° above avg.); precipitation 2.5" (1" below avg.); Jan 1-6: Rain, then sunny, mild; Jan 7-11: Showers, then sunny, seasonable; Jan 12-19: Snow, then sunny, warm; Jan 20-24: Rain to snow, then sunny, cold; Jan 25-29: Rain and snow north; sunny, mild south; Jan 30-31: Blizzard.

FEBRUARY 2012: temperature 28° (5° below avg.)

I think the part about january being 5 above normal will be close, of course the time periods during the month are hard to predict for anyone that far out but overall not bad for the monthly departure Regarding February I think it will average below normal but 5 below is a stretch.

[Brian5671]

So much for the Blizzard on 1/30-31

[donsutherland1]

Don if I remember correctly your only "fail" was in thinking the strong blocking would return late last winter?

Thank you for the kind words.

That's correct. I busted with that end-of-winter call. Hopefully, upon reviewing things afterward, I have learned some things that will allow for better insight should such a situation arise again. Needless to say, long-range forecasting remains a high-risk exercise and that means that there will be more busts at some point in the future.

[am19psu]

IMO, if one recalls some of the MJO forecast diagrams, those forecasts have been even worse. If one looks back at the MJO, one finds that it has been quite "sticky" in the "warm" phases (for the East). December saw the MJO in Phase 4 or 5 94% of the time. Through 1/23, the MJO has been in Phase 6 70% of the time. Until there is evidence that the persistence of the MJO to lock into one or two predominant phases is breaking down, I'd be cautious about assuming a progression anytime soon into some of the colder phases, regardless of what the ensembles might be suggesting.

The ensemble phase space diagrams have been next to worthless, but some of the statistical products have been quite useful in the 8-14 day and 15-30 day range.

[Brian5671]

Thank you for the kind words.

That's correct. I busted with that end-of-winter call. Hopefully, upon reviewing things afterward, I have learned some things that will allow for better insight should such a situation arise again. Needless to say, long-range forecasting remains a high-risk exercise and that means that there will be more busts at some point in the future.

The blocking went away last Feb and has yet to return..who would have thought that last year when things were so good...

[Stormlover74]

It's also silly to ever utter the phrase 'winter is over' unless its mid March or later. There may be no arctic outbreaks and February may be well above normal but the likelihood is still there that we see an accumulating snowfall at some point. I guess it depends on your definition of winter but for me it there's snow in the air and on the ground, it qualifies as winter (even if its 70 and melts the next day).

[TheTrials]

February looks rocking on the gfs, hope its not one of the its always 10 days away kinda thing

[Brian5671]

February looks rocking on the gfs, hope its not one of the its always 10 days away kinda thing

please...every model has show cold and snow 10 days out all winter long...

[WeatherX]

February looks rocking on the gfs, hope its not one of the its always 10 days away kinda thing

498 thicknesses in Southern CT at 288 hours.......that'll modify a bit I would imagine lol

[TheTrials]

please...every model has show cold and snow 10 days out all winter long...

i said, hopefully its not that. I know you like snow, be a weenie for a week, maybe it will help.

[TheTrials]

498 thicknesses in Southern CT at 288 hours.......that'll modify a bit I would imagine lol

what did you get Saturday? Did you ever get under that band?

[Brian5671]

i said, hopefully its not that. I know you like snow, be a weenie for a week, maybe it will help.

I was a weenie last week. And I head to Vail on sunday, so maybe I'll see some snow out there...

[WeatherX]

what did you get Saturday? Did you ever get under that band?

I was under 30dbz for hours....never got under the higher echoes, they were off to my north by a mile or so....ended up with 6"

[earthlight]

Good writeup.

The pattern did change for about a 7-10 day period...that is when most northeast stations produced negative departures from Jan 14-22 and the one snow event on Jan 21 (multiple snow events in New England)....the biggest failure of the pattern change was the inability for the EPO block to hold...it retrograded pretty far west as soon as it formed. The NAO never really looked very promising during this period so I didn't think the snow chances were all that great looking for the M.A., coastalwx and I described the pattern as "it gives us a chance" and that was for NE...it was "the PAC changes first" type of pattern....there was hope this change in the PAC would hold while we wait for a -NAO, but it never really happened.

The PAC looks to change to more favorable again as we go into early February, but the NAO still doesn't look all that great but at least it doesn't look as bad as it did before. The NAO is pretty important if you want large snowstorms in the M.A. You can get smaller ro moderate events without it, but in order to repeat the type of KU craziness of the past 2 winters, the NAO really need to be there...otherwise you are hoping for a perfectly timed setup which as many of us know, usually doesn't happen.

Good point regarding the EPO block. That feature really helped to develop the AK vortex. The model guidance struggled with that feature very similarly as they initially were modeling that ridge to build towards Alaska and the Aleutians around the Days 7-10 period. This had some people pretty excited. But as we got closer to the development -- it shifted pretty far west into a very bad position. The Polar Vortex was able to displace to the west from where it was and ended up to the east of the anomalous ridge...over Alaska and British Columbia.

[earthlight]

Very nice summary of what has happened. The forecasted vs. actual values on the major teleconnection indices have revealed less skillful forecasts than desirable. I suspect that the La Niña has had a role in that.

IMO, if one recalls some of the MJO forecast diagrams, those forecasts have been even worse. If one looks back at the MJO, one finds that it has been quite "sticky" in the "warm" phases (for the East). December saw the MJO in Phase 4 or 5 94% of the time. Through 1/23, the MJO has been in Phase 6 70% of the time. Until there is evidence that the persistence of the MJO to lock into one or two predominant phases is breaking down, I'd be cautious about assuming a progression anytime soon into some of the colder phases, regardless of what the ensembles might be suggesting.

Finally, on the brighter side, the persistent AO+ regime has been decaying. Negative readings are occurring more frequently and the AO recently fell to its lowest level in just over a year.

Don, thanks for the kind words. Very much appreciated. You've been absolutely terrific this winter as always. The MJO phase diagrams have been woeful this year to say the least. Even the Euro and Euro ensemble diagrams which are available have shown very little consistency. As adam said above -- the statistical data has been slightly more useful this season.

I ultimately think New York City will end the season over 10 inches of snow. But at this point I think the chances of them reaching over 20 inches are decreasing rapidly.

[jm1220]

Don, thanks for the kind words. Very much appreciated. You've been absolutely terrific this winter as always. The MJO phase diagrams have been woeful this year to say the least. Even the Euro and Euro ensemble diagrams which are available have shown very little consistency. As adam said above -- the statistical data has been slightly more useful this season.

I ultimately think New York City will end the season over 10 inches of snow. But at this point I think the chances of them reaching over 20 inches are decreasing rapidly.

Awesome write-up, and as always, very informative.

That AK vortex has been our downfall since day one, and I totally agree that we won't have a widespread, major winter weather event with it still there. We lucked out last weekend with the (for most people) light to mod snow event, but in this pattern I think it's the best most of us could do. And obviously, we can't lock any cold air in either.

A month ago or so, I thought we'd finish around normal for snow, and it could still happen if we luck out with 1-2 bigger events late season, but now I think most likely we finish well below normal for snow. It was destined to happen sooner or later.

[earthlight]

Great essay, John!

We just can't seem to get rid of AK vortex this winter, for any long period of time. As long it keeps reasserting itself, we won't see a sustained cold and stormy pattern in the East Coast. That doesn't mean there won't be any snow. But we'll be very much threading the needle. I also won't believe any blocking the models or ensembles show beyond 144hrs. Even they show some consistency. As you said, too many false signals this year.

Btw, I don't believe the +PNA showing up on the ensemebles will be help us much in early Feb. The PV over Alaska and Sibera regions, is going to lock up cold air in those regions. If you look at the 0z GEFS 2m temp anomalies below, we are still running above normal, through day 14. Ironically, we got a first appreciable snow this winter, when the PNA was negative.

http://www.meteo.psu...2_0z/tloop.html

Thanks for the kind words! I definitely agree in regards to the Alaskan vortex. It has been a semi-permanent feature of our pattern for much of the winter. We were able to lose it for a while several weeks ago -- but at that time the Atlantic and Canadian pattern were in shambles with the PV oriented over Greenland and much of Western and Central Canada in above normal anomalies. Shortly thereafter, the Alaskan vortex returned and the pattern turned ugly again.

I agree in regards to the temperature anomalies and little help from the PNA. But I think, if we can get enough amplification there, we could see a big storm on the East Coast around super bowl weekend or around that time. Model guidance this afternoon is still pretty firm and anomalous with that feature with a ridge axis over Boise and positive height anomalies into Western Canada. Despite the lack of an arctic air source, the amplification could be big especially comparatively to what we've seen this season. We will see.

http://www.meteo.psu.edu/~gadomski/ENSHGTAVGNH_12z/f276.gif

http://www.meteo.psu.edu/~gadomski/ENSHGTAVGNH_12z/f300.gif