frd

This is not a good sign, at least initially.

Did you read what I have in the first line ? I did mention they feel the warmest winter ever is possible . < Here are my notes : They feel the polar vortex takes up camp in the Eurasia / Siberia, if that happens then expect the warmest winter ever. > Now if they are wrong and the PV weakens, or there is HL blocking , etc. They risk a rather substantial seasonal forecast bust , and then it becomes two years they have to revise. Massive amounts of evidence ( climate warming, analogs, persistence, Nina background, West Pac warm pool, + NAO persistence, etc. ) all point to warm winter in the Mid Atlantic and SE. , including large portions of the country. However, I am not sold yet on what transpires this winter. I still like late November and early December as an opportunity for cold here.

Yes

Hopefully they don't have to reverse course like last year. But, I am hoping for that.

BAMWx Winter outlook - I summarized the webinar this morning. One word, warm. Opposite last year, and really following Nina climo. Here are my notes : They feel the polar vortex takes up camp in the Eurasia / Siberia, if that happens then expect the warmest winter ever. They feel low sea supports a poor cryosphere and no cold air source for most of the United States. They stated a basin wide Nina supports a very warm winter. They mention the QBO missed the Easterly phase and the West phase is not conducive to a - AO. This favors a very warm winter. Last time we had a - NAO winter was 2011. Recent climate suggests it will not happen. Carbon release = arctic warming and seeing a strong PV already, from fire burn. They see no chance at a - NAO. A very warm winter again. Low chance of a SWWE. Only hope is that the PAC might induce PV stretching or elongation. They feel the MJO is active the next month or two. Best months for cold ( if there is any ) might be shoulder months of December or March due to the weaker PV as compared to very strong PV in Jan and Feb. MJO really favoring phase 5, but movement is expected , the standing wave might be changing. Have had the standing wave for over a month. Most models favor a cold Alaska and a warm US except the PAC NW. Models are really at a consensus for a warm winter, with little if any snowfall in the East. Lastly, they mention any cold air does that make it here will have very little staying power.

Seems the MJO's Eastward progress has slowed, at least for the time being, with the latest AO forecast consolidating on a consensus move to + 4 SD, a very significant development. However, after this, a drastic move down is forecast to begin, possibly associated with the MJO moving into more conducive phases, along with changes in the Kara Sea region. ( possibly sea ice related ) These developments may promote a change later in November within the NAM. Possibly even a elongation of the PV later in the month. Even though the latest guidance forecasts a stronger PV, at least short - term. The recent incredible advance of NA snow cover might have played a role in the record cold out West. As snow cover in North America either stalls, or even decline during the next 2 weeks look for another increase mid November going into early December. Possibly combining with a negative AO and or -EPO change to bring much colder air onto the East later November and early December.

Presently the polar vortex is strengthening but hopefully by the third week of November there are some signs that this may change - highly speculative the latest models from the GEFS shows the strengthening of the polar vortex currently. Actually some modeling posted by Simon at his strat site indicates a strong(er) pv for the next 46 days, which fits the seasonal models. Dr. Amy Butler posted a cool scatter plot which shows in a Nina you can certainly have pv disruptions. And like the NAO hard to predict with skill.

Never stated the winter will be awesome for cold and snow. I would at least entertain the possibility of a cold period in December, as well as some significant temp swings. I still feel that things are progressing for some cold in November as well. The Ural High looks to set up and may stay for a while. Contrasting forecasts regarding the pv from the GEFS and the CFSv2 continue. Also, the Nina is changing up a bit in terms of expanse. That is important to consider for a seasonal forecast despite what the models are showing in the high latitudes with a lack of blocking presently. .

I believe signs point to a normal December in the Northeast temp wise. . Expecting a change although temporary to a more blocking pattern. Advantages in regards to the SAI I feel contribute to a cold(er) December period. Of course speculation. NH and especially North Amercia snow cover still look to rapidly expand next 5 to 8 days.

Looks to increase significantly over the next 7 days.

@psuhoffman knows more about this then me but I believe there may be a connection according to some mets that certain phases of the MJO correlate with a + AO and some with a - AO. It is much more complicated then what I listed here tending to do with winds, circulations and the PV. I believe TIP mentioned phases 2 to 6 equate to a more pronounced + AO , while the other phases are more so opposite. I find it interesting that we are now in phase 5 with a +AO and a pv that is getting stronger. Ventrice mentioned yesterday we may make progress to MJO phases 8 and 1 in November. If so, could that promote a weakening pv and a transitioning AO to a negative state? Mid November looks interesting to me. Don't forget too the development of the Ural High as well.

SAI and the Ural High are two different things as you know. I certainly put more faith and value on the Ural High connection then tracking weekly snowfall above 60 degrees North.

With the amount of busted winter forecasts the last 2 to 3 years I wouldn't jump to any conclusion. Solar minimum might be included in the current grouping of crazy indices such as the QBO, MJO wamer phase, and others.

Maybe the GFS wasn't so crazy with the phase potential. As mentioned a couple days ago, we may get a wave breaking event .

Everything is out of whack with the indices such as the QBO for example and I am simply mentioning something I read from Tip over in the NE winter forum. I thought what he mentioned supported some of the forecasts last winter regarding the solar min and a winter - AO . Later I read that there is a delayed factor, and actually the effect of a solar min may have more to do with its impact on the North Atlantic currents, ( and the - NAO ) . The ocean outcome on the NAO domain may take some time. HM mentioned the Greenland summer ice melts since 2013, and how this is messing up what you might expect. Or, as HM stated, it throws a monkey wrench into the possible correlation of the spring SST tripole and the ensuing winter's NAO phase. As for TIP he stated this in regards to the -AO and solar minimums : (please note - this is only a portion of his post - see the bolded part ) < I personally believe the recent observations wrt to the HC also play a role in enhancing the +AO, because: .. intuitively, the 2-6 phases of the MJO are probably getting a large/super synoptic scale constructive interference pattern by the current +HC ... which offers an early clue as to +AO winter ... experimental. Which is interesting, because the solar minimum going back hundreds of years of reanalysis ..certainly correlates reasonably well if not fantastically so, with the -AO ...again...we're stuck with diametric signals here. >

Last couple years we had good gains and I believe record North America snow cover in early December . Then, after December 20th it starts to shrink due to Pac air and a warmer NA pattern. Last year, and the year before were very abrupt turn around. However, my speculation is that we at least may get an impact from this moving into mid to later November, in terms of colder air . The SAI and extent regarding a connection to the winters dominant ensuing AO phase has basically be proven false. However, we do need a healthy cryosphere to support significant cold in our region. We may get some a few -EPO intervals this winter.

Look at the winter thread I covered it there.

For those who follow the PDO , this is an eye opener. As bluewave noted, you do not typically see this in a Nina. Oh, and as you can see from the image below unless you are talking real time cause and effect, don't get excited just yet. Just look at last December 1 st and then the following Jan 15 th time period. We went from + PDO to negative PDO in a matter of weeks, with a two point deviation decline. < The PDO isn’t following the La Niña playbook this fall. This was one of the biggest PDO increases during a La Niña in October. But as we have seen since the record North Pacific warming in 2013, these monthly values can really jump around a lot. Last winter we went from positive in December to negative during January and February. It all comes down to how the North Pacific ridge behaves. >

Beach chase coming up !

Interesting https://www.osti.gov/biblio/1613223 Ural Blocking as a Driver of Early-Winter Stratospheric Warmings Abstract This study explores the early-winter atmospheric response to Ural blocking anomalies in November, using a nudging technique to constrain the temperature and dynamics in a high-top atmospheric model. Persistent Ural blocking anomalies in November are associated with a warm Arctic/cold Siberia pattern and increased upward planetary waves entering the stratosphere, leading to a warming of the polar vortex. This stratospheric response then propagates in the troposphere, leading to increased occurrence of the negative North Atlantic Oscillation in December and January. In contrast, simulations with perturbed Barents-Kara sea ice and Siberian snow in November do not reproduce a significant atmospheric response. In simulations including a slab ocean, the Ural blocking induces Barents-Kara sea ice and Siberia snow anomalies that resemble composite analyses from observations. These results highlight Ural blocking variability in November as a robust driver of early-winter stratospheric warming while questioning causality between sea ice/snow and Ural blocking anomalies.

A look at the latest CFSv2 and the GEFS 35 day forecasts we see overall the early season vortex still close to the seasonal ERA5 mean. The CFSv2 actually a little below the mean, with the GEFS slightly above the ERA5 mean. While the 35 day GEFS tracks the PV slightly above the seasonal ERA5 mean.

Speaking of the Ural High and the Scandi - Greenland pattern, maybe showing up in a more significant fashion for the month of November. Worth following, as the implications are significant, both short-term and long-term.

Many of those factors we have heard already, especially the possibility regarding the poleward Aleutian ridge. Wondering the effect of less sea ice, however, my thoughts focus on rapid snow cover up North along with a November enhanced - EPO / +PNA later November. Snow is indeed expanding now in week 42 up North. How long the SST configuration lasts off the West Coast / North Pac is up to debate. I am not so sure about a + NAO though, feel there may be a couple - episodes. Speculation on the Ural High connection. Keep an eye too on the Scandinavia–Greenland pattern . Although hard to predict beyond week 2. More about that on the link below. https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.3892

So true. Only with climate adjustments and weighting can you even begin to consider older analogs .

Speaking of analogs, take from this what you want. Both threads below have very interesting takes on climatology, analogs and SSTs . 1942 did happen during WWII.