The pattern continues to change towards one that favors a flip in the pattern resulting in a much more wintry one for the Eastern US. We can see this happening currently in our stratosphere. Notice the warming is taking place across Eastern Asia in the stratosphere and corresponding to a deep trough. This results in that typical cold PDO pattern of Bering Sea block and GOA low. The end result is what you felt today in the Eastern US with a warmer pattern.
Here is the 72hr 30hpa stratosphere temps:
Now the 72hr GFS Ensemble Mean:
Two things stand out from the two images above:
1) The cold stratosphere over the United States and the higher height anomalies that exist.
2) The trough over Eastern Asia and the Bering Sea block becoming cut off. This results in a strong negative AO displacing another vortex into NE China.
Now as we go ahead 10 days into the Stratosphere notice the changes:
See it better at 70hPa (lower in Stratosphere)
The stratospheric warming shifts eastward and is noticeably different across North America. In addition we see the colder air in the stratosphere really focus over Greenland extending into the Barents Sea and Kara Sea across the arctic. This is important because it is going to make some great sense in the next image:
Notice the correct changes showing up on the 7-10day models from GFS ense mean and the European. I labeled 1-2-3-4 on the Euro chart to correspond with:
1) The pattern shifts east- Notice the trough axis shifted from Eastern Asia towards a trough axis to the east of Japan! Look what it does to the pattern downstream in the Gulf of Alaska...
2) Ridging builds into the Gulf of Alaska and replaced the strong vortex. This allows cold air to spill into the CONUS. Also not the trough around the dateline (more on this later on in the blog).
3) Negative NAO in the area of very strong stratospheric air
4) Connecting to the Caspian ridge which is a signal that our PNA ridge will get boost shortly after this time frame. Also supports a Neg AO
The models today are really hinting at the switch starting around December 12-15 with the favorable cold and snow heading to the Eastern US after December 15th.
More support for the above:
The Convection has returned to the Dateline something we did not see much of last Winter. The main reason is the warming SST anomalies and the west based warming in the Equatorial Pacific:
The warming in this region is going to go up and go along with the pattern change and really give the Pacific a warm PDO look in the second half of December. A kelvin wave (pocket of warm waters) is going to push eastward and was recently initiated as seen in the images below from my presentation at the Winter Workshop:
After seeing the tremendous drop from 18.77 to -16.74 it was a telling sign that something has developed and that feature was a Kelvin wave as it can already been seen impacting the SST anomalies across the western basin of the nino regions (NINO 4).
The Westerly Wind Burst signifies the warming that should take place. When the easterly trade winds are weakened it allows warming...when the easterlies are strong it leads to cooling.
The convection across the dateline extending to the NW is around for the long haul it appears with the latest trends and this means the GOA vortex cannot hang around much longer with this persistent convection. In the day 7-10 Euro and GFS ens mean images above notice the trough around the Dateline pulling southward (mostly euro).
The latest negative east asian mountain torque event is sending the negative AAM anomalies poleward which further supports more warming heading towards the GOA. This arrival is expected between the Dec 12-17th. So with all this information supporting a change around mid month it is hard to ignore it. And I expect the models to play catch up rather than leading us on as we go through the long range!
And the latest trend on the MJO signal (which makes sense with the GWO) is heading towards phase 1!
High AAM is something we also have not seen in quite a while (aka last winter) so we are sitting nice right now if you like cold and snow in the East!
And a phase 1 in December looks something like this...
Ditto on Rob and NKuss947's comments on the old crew . Like all the new additions to the site and the hard work that has gone into it, but miss the :family feel we had before.Would be nice to hear from the old crew again.
Wow it is funny to hear the "old crew" lol I been here since fox lol still new to it all so I read more then anything but doc oak tooch and especially HAIR HOZZAH always kept us informed and it absolutely lost that family feel. It wAs like we all knew each other and never even met. I hope they come back and I m glad u guys r still here
many of the old crew will return, just before the next real threat.
I don't think we'll see any HECS and possibly a MECS because of the lack of El Nina. There is plenty of warm water off the carolina's but without the El Nina it's going to be hard to tap a lot of moisture out of the Gulf.
Phillywhiteout, very nice response ( and I appreciate it). I love Mike's blogs as he details everything he sees with great information. Poconos, I should have attended the workshop. I missed a great learning experience as I am just a follower of weather and would love the ability to understand the reasons and whys of a particular weather pattern.
Phillywhiteout, I do miss the old timers ( Wenner, Snitki, Doc, Icebox, Hair, and Oakland). They kept the banter going back and forth and it seemed much more livelier in the past with all of them blogging during the winter months. Too bad they all left.
Paul, sign up for the next weather workshop and you will understand why forcasts change. Why did NOAA downgrade Sandi to a tropical storm when everyone knew it was increasing in strenght and hit with a Cat 3 pressure. (Which 100 billion dollars in damage is equivalent to a Cat 3 storm).
Anything past 2-3 days is speculation. It's about teleconnections and trends.
also read andrews blogs. He has some great info on Analog comparisons. That's why there's a good chance we will see snow.
BMR, you make great points. So I guess my question is why don't mets alike see the same setup? In other words, you talk about the North Pacific being way above normal and warm Decembers rarely lead to a cold and snowy winters. I am trying to understand why all mets wouldn't see the same things you or others like Joe Lundberg and Brent Anderson at AW see. I am not trying to stir the pot. I am really trying to comprehend why one person can see signs of a warm winter and another sees a totaly different setup with cold and snow. Aren't we all looking at the same models and teleconnections? It makes it very difficult to side with either side when it comes to long term forecast.
Personally, I would be very worried.. The North pacific is still running way way above normal... It continues to fuel the jet stream to flood mild pacific air into the lower 48... Alaska again is stuck in another ice age as the cold air is just stuck... A very warm December rarely ever leads to a cold snowy winter... This December is actually going to be warmer through mid month than last December.... The pacific ocean has been devastating to us... And what's funny is most of the news coverage is about global warming which if the pattern would just flip we'd be freezing right now.. There's a ton of cold air locked up!!!!
Phillywhiteout- Not worried. Models have a tough time with pattern changes and this is no different. With an increasing PDO to near neutral values (expecting it in next update) and stratosphere the support for a ridging near the Aleutian Islands again is not likely.
No one was really expecting December to be below average temp wise with the first half torch but the second half still looks really good.
I've also been thinking the same regarding the cold weather. Last year most of the mets kept saying wait two more weeks and the cold will arrive . . . well, we all know how that turned out. Another cold weather waiting game for 2012. I hope the snow we recently had wasn't our snow for the year like the 2011 October snow was all she wrote last winter.
To go along with what Paul is saying the gfs does show a flat progressive pattern to continue with average temperatures, nothing arctic. Could it be wrong and change sure? Could the cold air be too cold sure and actually stay warm. But as of now in the long range gfs it does look like last years pattern, at least until the 14th as of now. I only look at the 264 gfs.
Mike, great write up. However, to play “ devil’s advocate” there is another school of thought out there. Some well-respected mets over at Accuweather ( Joe Lundberg and Brett Anderson) paint a warm picture much if not all of December. Pattern is looking similar to last year’s. Are there significant differences that you can point to that would lead you to believe the outcome will not be similar to last year’s disappointment? I am a winter lover myself and it would be nice to count on a colder solution towards the end of the month ( maybe even have a legit shot at a White Christmas).