Chicago Storm

Comical...

Trendz...

As expected, mid-month has brought a pattern change, which started with our crap-tastic storm system last weekend. Increased chances for snow and cold are possible/likely for the foreseeable future, compared to what we have seen thus far this winter. However, I am not as gung-ho as others regarding a sustained winter period for the next several weeks. While the AO/NAO/EPO have been trending down, from being well positive to being in the vicinity of neutral to low end positive for the near future and extended, no serious dip into negative territory looks likely. (There has actually been a trend among ensembles to bring back a well positive EPO, but I'm not fully on-board with that for now.) Additionally, the deep -PNA that we've been in and needed to continue is expected to end, with it likely heading to around neutral to low end positive. Additionally, the MJO has been rolling through deep phases 4-5 and now 6. There is high agreement in rolling through phase 6-7, and then looping back into the COD, before exiting once again into warmer phases most likely. I do think there is some chance we do clip phase 8 for a short time, though. Add in that the main PV will be in an unfavorable area for the period, only smaller/brief lobes may quickly slide through nearby. Thinking we see continued/additional shots of cold/snow potential, definitely more-so than we've seen thus far this winter, which is fairly easy to attain. However, I definitely don't foresee any sustained/long period of cold/snows, with several mild periods/rainers still mixed in...just perhaps not AS mild as they have been.

It's called we were in a +AO/+NAO/+EPO pattern. So no, it is/was not shocking.

The north guidance is not surprising, with a lack of blocking and continued +AO/NAO. .

The trend recently in this pattern has been for bigger storms out in that range to come in weaker/strung out/not-phased. Case in point see the strung out/un-phased system moving across the region and East Coast the past few days, and then the upcoming strung out system around mid-week. Both were shown as sig winter storms just several days back. .

It hasn’t been shown consistently, and given the pattern we’re still in...it’s probably not even worth much discussion this far out. .

If that happens in this unfavorable pattern...take it and run, and don't stop running.

Well...I was previously going to mentioned how the Euro and GFS ENS had trended towards showing the potential for a much more favorable pattern coming up after the first week of January (7th)...A continued +AO, though with an NAO trending more neutral to -, along with a deepening -PNA and finally a legit -EPO. However, the Euro ENS have quickly trended back in the opposite direction, and are now back to what they were previously showing...with the same pattern that has been in place continuing... +AO/+NAO/+EPO/-PNA...with a deepening -PNA. The GFS is kind of in the middle regarding things overall. There is also agreement between both the Euro and GFS ENS's on the MJO continuing to chug along, right on through the COD and into phases 4 and 5, which happen to be warmer phases of higher correlation at this time of year. I'd probably put more stock into what the Euro ENS are projecting, given their near stellar performance for a while now. If the Euro ENS are correct with teleconnections, combined with the projected MJO and upcoming movement of the main PV to settle in around Greenland in the future...more of the same pattern we've been in will continue (mild and snow-less overall), though more active overall. If the GFS ENS are correct, it will probably be a somewhat better pattern than we've been in, but still nothing to get too excited about. Probably a bit better cold/snow chances, however. tl;dr... zzzzz for now.

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All of the so called “guru’s” have failed this far. Not saying he’s one per say, but will lump him in given he’s almost always talking cold for somewhere. .

zzzzz... Edit: Should mention that since my last post last week, the GEFS caved to the EPS in showing fairly close to the same as below.

After that 1-2 run change, they reverted back. .

As you could probably figure out by the current/upcoming pattern, the Euro ENS were correct in handling/depicting a +EPO...while the GFS ENS failed horribly. The bad news...If ENS have a good handle on things, that upcoming potential pattern change guidance was hinting at to end December and begin January might be in jeopardy. The Euro and GFS ENS are showing a continued +EPO continue right on into early January. On top of that, the Euro ENS also have a +AO/+NAO/neutral PNA set in as well. The GFS ENS are a bit more subdue overall, more similar to what we are seeing now. Also of note, is that some of the GFS and Euro ENS have the MJO moving from the COD on into phase 6 for the late Dec/early Jan time-frame. If that were to happen, combined with the potential teleconnections in projected, and the fact the main PV will be up over the North Pole/Siberia...things *could* get even more torchy/snow-less...and that's saying something given how the past 5 weeks have been. Not saying that will happen... But the projected teleconnections alone should be a concern that an overall mild/snow-less pattern continues into at least early January.

The "people" have been wrong so far. So I wouldn't put too much stock into what they say. However on the flip side, it does appear there is support for the potential of a more favorable pattern for cold/snow around or after the New Year. The GFS ENS are more gung-ho on this than the Euro ENS though.

Equal chances either way that far out. However, it is sort of interesting at the same time that there is not even a long range fantasy storm heading into January.

A lot of valid questions/possibilities.

You know it’s bad when the GFS doesn’t even have a fantasy snowstorm the entire run...which extends into the first days of January. Not just for our region, but the whole country pretty much. .

12z GFS was a nice torch for Christmas, and the days prior.

What happens with the EPO is really going to shape the upcoming pattern. Euro ENS still want to bring the EPO + for a while, flooding much for the country with mild air for the most part. GFS ENS keep the EPO -, with a more up/down pattern...with cold shots and snow potential.

On the flip side to this... the Euro ENS and the +EPO it has is a perfect example of what can go wrong, potentially leading to a continued mild/snowless pattern.

ENS finally showing changes... Growing support for a neutral to - AO/NAO/PNA starting next weekend. MJO looks likely to head back into the COD, staying out of warmer phases. Add in the PV chunk that will take hold in the Hudson region. Should lead to more cold shots and chances for snow...finally...for next week. Hopefully can get something going for a white Christmas. .

Hopefully we'll be in a better place by then. Would be nice to have a solid white Christmas. '17, '16 and '13 were, but only featured 1-2"...the last solid one was '10 later.

tth, as alek would say. what has occurred speaks for itself. Fairly large area of 2-6 above normal. Fairly snow-less as well...ORD with only 0.1" and DTW with 0.2" since that time.