if you like COLD & WINTRY weather in the Eastern US; 0z runs are a disaster

well taking a look at the 00z Models there really is only one term to describe the medium-range models in the overnight period-- and If you love winter weather and cold that term is DISASTER.

So complete is the model reversal from the data on Friday that the East Coast stays warm right to Christmas. Keep in mind that the 12z Thursday and 0z Friday runs was showing this Low coming out of the Southwest tracking across Southeastern states and then to Virginia. The trends started to shift the track of the SW Low yesterday on the 12z runs... and now the 0z Saturday runs have continued the trend... taking this system well west of Chicago!!! That is a huge shift in the models in just a 24 -36 hr hour period!! And even though the event for the 12/22-23 is still 6-7 days out is remarkable to see that sort of massive shift in the medium-range models in such a short period of time.

The question is of course.. is such a shift correct? One of the rules are using medium-range forecasting is the rule of Model consensus. At this point in time and skill here in the early 21st century weather Models are of such high quality that when you see a massive shift like this in ALL or Many of the models -- be it SR or MR --on a particular run cycle ...such as 0z or 12z.. nine times out of 10 it usually means that the medium-range models are correct.

What has changed... that IS obviosuly the BIG question? Well several things . To begin with if you go back and looks at the MR runs from earlier this week you'd see some sort of Ridging developing over Greenland for next week and while it would not really constitute a classic - NAO the 5H rise over Greenland that the models were depicting would force the system in the Southwest tract further to the south and east keep in the lower latitude. Now None of the 0z models are showing that sort of Ridging now over Greenland.

Second many of the MR models from mid week shwed SOME sort Ridging developing over western Canada... yet if we look at most of the medium-range models at 0z we ee that there is no hint of that on the 0z runs through Day 10. And the 0z CMC and GFS ensembels are not much better.

In my view the prospect that the 0z Models are all wrong is NOT very good. We still have a time to hope that the models might shift back but if they haven't done so by Sunday the threat of ANY event for the East coast be it rain or snow... Is over. Moreover if we have not seen a shift back to the type or pattern we are seeing on Wednesday Thursday and Friday then the prospects of that the last week of the DEC would be even seasonally cold are greatly diminished as well.

Interestingly if one or to take a look at the SSTA the large bubble is very warm air located off a Southeastern Canada in and around Newfoundland has now completely collapsed.
SSTA map 0z 12/15
http://weather.unisys.com/surface/sst_anom.html

SSTA 0z 11/18
http://weather.unisys.com/archive/sst/sst_anom-061119.gif

This could as significant implications because when that pool very warm was in the Davis straits in late Septmber & October THAT is when we had the sustained - NAO over Greenland. Later when this pool of very warm SSTA moved South into and around Newfoundland... that is when the -NAO collapsed and we moved into the sustained phase of +NAO patterns.

Now however it appears from this data that we going to another change in the SSTAs in and around Southeastern Canada and in the far NW Atlanric. What exactly this means or whether not the pool very warm water in and around Southeastern Canada might re develop is hard to say. But if it does not this development -- and breaking down of the pool very warm water around Southeastern Canada could have significant implications down the road.