40/70 Benchmark

He is speaking from a mid Atlantic perspective. We are fine.

I'm pretty confident on an above average snowfall month north of the pike, at least. Here is my analysis from a couple of weeks ago, which is largely on track IMO...but the risk is colder. Expect this sale style of deviation from the MC forcing during the early portion of the season. December 2017-January 2018: December 2024-January 2025: An official SSW as defined by the reversal of the mean H85mb zonal westerly winds is unlikely, however, there is a low probability of one as suggested both by the minority of guidance, and the December 4, 1981 analog. Should there be a reversal of the H85mb zonal winds, December 4th is a good estimation of the when the PV will reach its weakest point before the split, and subsequent recovery begins. As per the expectation of a significantly weakened vortex resulting from bonafide warming that will fall short of a full zonal wind reversal, the December 2000 event is the preferred analog. This is appropriate since 2000-2001 is also the top analog from the seasonal composite. Accordingly, the polar vortex should have consolidated back to at least something approaching climatological levels prior to Christmas (18th-24th). It will then continue to strengthen with moderating temperatures in the east, per research conducted Lee et al (2019), which indicates that the arctic high regime is favored for less than 20 days following a weak PV. This is also consistent with the onset of a reflection event on December 21,1981, just over two weeks after the December 4th SSW. There is a slight chance of Ku event between the first and 15th of the month. The PNA should average negative during what will be active month, with numerous SWFE and overrunning events commencing by approximately the 10th. The probability for a White Christmas is above climatological levels given the active pattern and at least seasonable cold throughout the first half of the month, but it remains dubious for the coastal plane given the milder turn prior to the holidays. In fact, the proverbial "Grinch Storm" is more likely than not. A Pacific trough should begin to evolve towards the end of the month in conjunction with a rather stout PV, as a mild pattern ensues to ring in 2026. The month of December will average near normal, anywhere from -1F to +1F, except near normal to +2F across the middle Atlantic.

Same page with him on that, but I think we see a reversal in February.

December will be very good for us...it's the mid Atlantic that will take the shaft. Not worried in the least. My December analogs show this well.

I think I'll do fine in December.

I don't expect any KUs in December...more of an overrunning/SWFE threat, as others have mentioned....although I did include a slight chance early on.

The cold isn't going to just surge in here with at least minor resistance from the PNA...not the arctic stuff, anyway...it will take a week or so into December.

I think that is the favored outcome.

I meant to look through the behavior of the MJO for my entire analog set in putting together the forecast at the end, but I forgot to do it...if I mess up the December progression and rush the warmth, that is why.

This is my complete December list: December Analogs: 2021, 2017,2008, 2007, 2000, 1981, 1970 Seasonal: Primary Sensible Weather Winter Analogs (*Denotes Strongest Analog): 2024-2025, 2021-2022, 2017-2018, *2000-2001, 1970-1971

I liked Dec 1970, 2007 and 2008 as SWFE analog months.

I haven't started looking at discrete threats....still in cool-down mode after my seasonal deep-dive. Probably fire up the package next week.

No, I don't expect you to get screwed badly in a SWFE...maybe a bit less, but not pantsed. That is more likely in a coastal later in the month.

Folks also need to remember that the MJO isn't the sole pattern driver...it's an element that can either constructively or deconstructivity interfere with the background forcing. Ie...it's one ingredient in the dish, not the main course.

Absolutely....especially closer to the latter portion of that period.

I thought I just mentioned the MJO in my reply...?

Obviously I'm not a met, but my stance is the pattern begins to break down by mid month into Xmas...probably not "warm". I may have def. rushed that though given the weak antecedent nature of the PV in conjunction with the anticipated behavior of the MJO. Just don't be surprised to see the second half trend a bit warmer.

This probably ties into the rule concerning the higher amplitude MJO waves in October preceding colder winters that @bluewavehas referenced, though I know that is a more recent phenomenon. I do wonder if those seasons were higher amplitude in October. Looks like 2010 would fit the mold...not so much 2005 and 2000.

While this is true, I don't think that is the reason in this case....there is a seasonal element. No question cold and snow gets more hype in the winter.

VOTE

Bias is easy to discern among those who actually venture to issue a forecast, but it's also there amongst the Sunday AM QBs...just more subtle. The tell tale sign is the presentation of one-sided data. I think a quality that is inherent of all good posters is a willingness to present data that is representative of the range of possible outcomes. ...ie the folks that relegate themselves to posting about the MC and -IOD are just as culpable as those in the SSW/phase 8 circle-jerk. We all know the ones on each side....you know what the data offered will favor before reading it.

Granted there are more cold mongers, but we all know the select few who only post concerning indicators in favor of warmth (not Don). To each their own, but I try to be limit the bias and keep it real.

I do agree that the majority of it is a cesspool, though.

Depends whom you follow. DT has been all over it.