UPDATE ON WINTER CLIMATE MODELS FOR THE WINTER

Posted by wxrisk | GENERAL,WINTER 2012 -13 | Thursday 22 November 2012 11:41 pm

22 NOV  2230 HOURS   EST …   STARDATE  201211.22

 

There is some new information which of come out recently since I issued the final winter forecast which I believe is significant because it shows that continue trend in the CFS Model for a colder DEC and JAN east the Mississippi River.
This first image consist of three maps all focusing on December of 2012. The first two of these maps have already been posted in the FINAL WINTER FORECAST … But since then the updated version has come out . Normally I would not make a a big stink about this new run of the CFS…..
But the changes here in the December and January are pretty significant especially if you look over the last 30 days.

And remember each one of these maps covers a 10 day period. The first interval or 10 days was from middle of OCT…. the SECOND 10 day period 3-11 NOVEMBER.. and this most recent update covers 12-21 NOV.

Here are the DECEMBER CFS temperature forecasts over these last three 10 day periods. The trend it should be obvious and quite clear that since the middle of October the CFS has been turning colder and colder.

Now remember the CFS ten day mean average is NOT simply one model that is run on one particular day.  The CFS consists of 4 runs EACH day … for 10 days for a 40 member ensemble.
looking at JANUARY 2013… we continue to see the same trend with each new 10 day increments of time and each new 10 day period showing temperatures turning colder and colder east the Mississippi River. The trend here in both months are quite noticeable and I believe to be consistent and significant.

Next I have presented the mean pattern being forecasted by the Chinese climate model for the northern hemisphere  for December   January February. Posting this map may draw some cynical comments and derogatory reaction but rest assured that individuals make such comments are the actual idiots.

We all know that there are weather models out there which are generally superior to the operational GFS and the GFS ensemble.  It would follow that there are climate models out there which are superior to the GFS.   One of them happens to be besides the European model is the Chinese climate model.  The Chinese climate model did a remarkable job with the drought during the summer. I have no idea if the models correct are not with its winter forecast but it shows a pretty impressive pattern for the East Coast. In fact if the Chinese models correct this would be a historic winter for most of the East Coast as well as the Tennessee Valley and the lower Midwest.

Also here in case you missed it is the latest upper air forecast for week three and week four from NOV 22 CFS . What is significant here is that it continues to show that the first half of December is NOT going to feature Below Normal temperatures and it does NOT look very stormy for most of the country. I said this back in my initial winter forecast and I don’t see any reason to change it.

However by week 3 DEC 6-12 we see a very strong blocking feature over North Central Canada which really counts as a extremely slow large -NAO. The week 3 pattern is actually one of those rare instances where even though the NAO is large and strong … Temperatures do not show a cold pattern. The problem is that we continue to see that trough over Alaska. That feature which in the weather business is called a positive phase of the EPO (+EPO) is forcing a trough over the far eastern Pacific and along the West Coast of North America….. or a -PNA pattern. As a result the cause of the -NAO block over North Central Canada is so large… the interaction between this feature and the -PNA means that there’s no cold air flow coming into the U.S. As result temperatures dec 6-12 will be pretty mild for most of the country east the Rockies.


However by week 4… the +EPO is gone… and replacing it is a -EPO feature… which means a strong West Coast Risgw extending all way up into Northwest Canada. The expansion of this RIDGE over Northwest Canada means that the-NAO Hass to be pushed to the east a little so it moves into the more classic position over North America— between Labrador and Greenland. This setup +PNA and -NAO and a -AO is very favorable for significant East Coast or eastern U.S. winter storm to develop in mid December. The dark green areas shows the huge trough over the northeast quadrant of the country. Of course at this point in time it’s impossible to say as to whether not this is a Great Lakes or New England Low or a true East Coast storm

 

 

1 Comment »

  1. Comment by ClayinBonAir — November 23, 2012 @ 12:13 pm

    Now we’re talkin, Dave!

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