0800 EDT 9 NOVEMBER
First let me start out with a couple of announcements. There is going to be a new subcategory on the WXRISK.COM page.. called HARDCORE
This subcategory will be dealing with the serious meteorological analysis. I hope to update this subcategory/ page EVERY DAY around 0700 EDT or so. It is going to be primarily aimed at energy meteorologists Grain Meteorologists TV Meteorologists and all those who have a need or dseire to read serious hardcore meterology. It will be free for all. The subcategory HARDCORE will NOT be for the layman or average person and I hope I will make that make that quite clear. For average folks that are NOT Hardcore weather nuts or professional Meteorologists … I will be using WINTER 2011-12 subcategory/ page.
Increasingly there are more signs that a significant pattern change is coming for North America. And that even though the next 7 to 10 days over most of eastern CONUS — and eastern Canada for that matter — are going to see some pretty impressive warm temperatures for the middle of November— things are starting to move and the pattern is beginning to shift.
In the last discussion -NOV 5– I pointed out the several key players hemispherically which have to change with regard to the current pattern… in order for some sort of reasonably winter like hemisphere pattern to develop.
IMAGE # 1 we see TWO Maps …. the Map on the LEFT side is the CURRENT hemispheric pattern as of November 8. This is from the 12z initial European model (ECMWF) ENSEMBLE and again of highlighted some important key features.
As I pointed out back on Saturday we still only have one large intense Polar Vortex which is situated over the northeast the slopes of Siberia. There is no PV anywhere in the western hemisphere… which is one of the primary reasons why the pattern has been so Mild. With the polar Vortex on the other side of the arctic circle there is no large pool of cold air in the western hemisphere to draw on. We can see this on the map on the right side…. The white line shows the boundary of the arctic air and as you can see it’s extremely far to the north a specially for early and middle of November. So even if there was want to get a large cold High to come south it would consist of mile Pacifc air. In addition we can see the strong ridge over the eastern third or eastern half of the CONUS and the Scandinavian rage extending from the Ukraine into central and northern Norway and Sweden.
In IMAGE #2 … there are 3 maps…. all based on the 12z ECMWF of 12z NOV 8… and all 3 are valid for NOV 15. The first map again is a large scale hemispheric view. First we can see that the model is showing that the PV is SPLITTING into two pieces.
SECOND the RIDGE over Scandinavia has now moved into the UK and is building towards Iceland. This movement counts as a eastern based – NAO feature.
THIRD… the strong ridge over the eastern half of the country has been pushed more towards the southeast and Northeast US coasts.
FOURTH… We can clearly see a massive trough developing over western and Central Canada…. and the big ridge over the north Pacific is sliding WEST towards the international dateline. This is allowing for the mean trough which has been over the West Coast to slide into the Rockies.
The 2nd map in IMAGE 2… Shows the large scale cold air pouring across the Arctic circle into western and North Central Canada for the first time this season. The third map is just a more localized view of this… with the arctic cold finally poaching the was Canada border for the first time this season. Also note how very warm it is the Southeast and Northeast US.
IMAGE #3 is the day 10 European map… Valid for November 18. Again we have three maps in image number 3 to look at.
The first image shows the hemispheric projection of the day 10 European. We can clearly see two polar vortexes have formed…. with the first or original PV now located over Central Russia near the Ural Mts. This is important because if you recall the original position was over north side of eastern Siberia. This movement of PV #1 to the central Russia is allowing to Pac Jet to relax— meaning that the Pacific jet is more likely to buckle or change shape. And note that the powerful southeast U.S. ridge is now mostly out into the Western Atlantic Ocean.
The second map in image #3 shows the arctic air now moving into an across the U.S. Canada border… And that the Arctic air is rapidly building up too impressive levels over all of western and North Central Canada! Again why is important?– IF Canada does not have any colder air in it… it neither will the U.S.
The Third image is again the US Map … of the day 10 European model. We can see the cold air finally moving into Northern Washington State hide a whole Montana North Dakota and Minnesota.
IMAGE #4 is the chart of the 12z MODEL showing the NAO and EPO patterns.
There are four charts: the top left one shows the overall NAO. And you can see that most of the models show this feature becoming consistently but moderately negative over the next 10 to 14 days. The image on the top right shows the west based or GREENLAND NAO. Note here that the graphs are all very close to Neutral… which is telling us that the Scandinavia block has not reached as far west as Greenland.
The bottom LEFT map is the east based -NAO and here we see a strong Negative signal which tells us that the Scandinavian ridge does move west over the next 2 weeks. The Bottom RIGHT map shows the EPO phase which finally moves into the positive phase.
LASTLY image #5 shows the PNA trends and all the model data continues to show this feature to be running strongly negative for the next two weeks.
SUMMARY: the pattern is clearly going to start changing over the next 10 days. But the key here is to recognize that it’s starting to change. While all this is going on in the northern hemisphere at the high latitudes most of the next 10 days over the central and eastern U.S. will be mild. For most people today will be seeing the weather pattern and their conditions every day… and be wondering “ where is winter?”…. ” where is the cold air?”…
Assuming that the European ENSEMBLE means are correct…. true arctic air will finally reach western and central Canada by the 15th… BUT not the leading edge of the cold air will Just be reaching the U.S. Canada border by NOV 18 . Assuming all this is correct seasonally cold air will NOT reached the East Coast before November 20-22.
In addition even though the cold air buildup in western and central and Northern Canada will be impressive over the next 14 days… as long as the PNA remain negative… ( as long as the trough remains over the West coast or western third of the US) we are talking about a seasonally cold pattern in the U.S. With a -PNA there will be no mechanism for the arctic air building up and Western Central Canada to come south.
Now eventually once the -PNA turns neutral and then positive… All that cold air building up in central northern and Western Canada will be able to come south. And that could make for some mighty impressive cold air masses come DEC 2011…. let me tell you.
All in all if you like cold weather… Things are trending your way. Just remember… We have a long way to go before we get out of this super Mild pattern.