stadiumwave

If a split occurs, starting on JAN 7 per 12z GFS & warmong across artcitic continuing through end of run....then a great chance of a good period of winter in a lot of CONUS (esp eastern 2/3) is a good probability in the future. Can't guarantee the correct storm track for anyone, but the cold at some point would be a given. Sorry for the giant run-on sentence, lol. My wife, who is an English teacher, would scold me, ha! EDIT: Let me add that I do NOT think models have a good handle yet on whether the SSW results in split, & if so what kind of split, & how long does warming last. Models may handle that aspect poorly until 5-7 days before.

12z GFS

GEFS has a split

Several ensembles & the control have split for the last 3-4 runs. This is the first GFS operational run that I recall splitting.

0z GFS

Click & read entire thread.

Just simply means a big winter storm is likely as well in 3 weeks. Smart money on JAN 9-13 timeframe....supported by BSR as well.

Hmmm

Eric shares Roundys composite. Roundys 100 day low pass constructed analog for the same date:

Another look. I'm sharing because this is so cool looking! Watch it eat!

Rock & roll! Happy new year!

Good old "MJO confusion" model run to run variability I think.

But at that point it's already weak & decoupled from the troposphere and it really doesn't matter. Opens the door for increase HL blocking. Also that is classic precursor to a full-blown SSW which is defined by a reversing of the winds. Smart money is it's going to occur.

GEFS 10mb Anomaly GEFS control 10mb anomaly

Organic methods still looking good for cold that 2nd week.

With a month long +PNA. So, who cares

CFS continues to show NAO & AO drop around & after Christmas.

East Asia has a lot of troughiness being modeled Dec 16-29. Per East Asia Rule, correlates to east U.S. 6-10 days later. Somewhere around Christmas through 1st week of new year. The 0z GFS & GEFS changed drastically for Christmas Eve. Trend This does not appear to be a cold outbreak but some seasonal & perhaps tad below normal when systems swing through. Would support some possible snow potential somewhere during that period . EDIT: I could've swore I saw DEC 24 on the analog map, ha. My point was irrelevant except for the Christmas period.

JMA updated...great JAN & FEB JAN FEB

UKMET updated...great looking JFM 500mb 2m Temps 850mb Temps Precip SST's

Continued warming Strat warming episodes, weakening the SPV is probably fine as long as MJO cooperates. If not...need SSW & reset.

CFS Weeklies really swinging to colder look 2nd week of JAN as we've been discussing: That AO & NAO drop that far out is pretty significant. If models are correct on that period, and I think they're catching on, then expect that signal to intensify.

I've been up in the air about whether a full blown SSW is needed. I've about decided....yes. Either full-blown reversal or a significant weakening event to shake things up.