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They are riding a hot hand lately. I enjoyed the webinar they did a couple weeks ago, the conclusions are not mere analogs, or even modeling, but a combination of different methodologies. They are going with the colder December, 60 % / 40 % but low confidence, very interesting. I think later December we roll into real winter. I have never have experienced a winter that starts at the winter solstice, with the shortest days. That would be cool to have the flip start at the end of December, or right near the holidays. Uncle ( from NY forum) has analogs that point to a white Christmas. I could go for a marshmallow world by Dean Martin.

Great question. I am not really sure about the need to couple. First, there are different ways to get a vortex disruption/warming, etc. If you go simply by the QBO, and the descent, according to Isotherm we really need to wait for it to decline further, so his forecast of the best blocking is later in season. Personally, I like to see the forecasts of wave 1 activity and the vortex weakening. Are these forecasts correct, I am not sure. I would pay close attention to the next updated QBO value, and the progression of the NAM. I refer to this section of Isotherm's ( I bolded the interesting parts to your reply ) forecast and lets see how the balance of November goes and early December. Maybe it can provide us with hints for the sensible weather in our region for the holidays and late December. As Bob said, if we continue with a -AO later in November and early December it will mean red flags as to the seasonal modeling. @Isotherm snippet from his winter forecast : << The QBO easterly shear stress will eventually down-well to z30; however, the pace of descent as evinced by the slope, and the temperature profile, suggests that there could be a multi-month period of weak positives or near 0 values, prior to the full transition into negative. Concordantly, the true negative phase should not effectuate tropospheric vicissitudes until the second half of winter, particularly February and March. At which time, it is more likely that the NAM/AO tends on the negative side, countermanding the more positive NAM/AO of the first half of winter. It is – additionally – critical to cognize that the likelihood of the stratospheric polar vortex reaching zonal winds of 40 m/s at the 10hpa/60N level in November is very high. Since that event is relatively anomalous, analogs may provide a further hint insofar as auguring the ensuing mean stratospheric (and tropospheric) vortex state. The vast majority of the cases wherein zonal winds reached 40 m/s continued to feature stronger than normal vortices during the winter. Often, reversals occurred in late winter (late January onward). In this particular winter, I anticipate that the stratospheric vortex will weaken significantly in late January, potentially leading to more tropospheric blocking in February. Whether this results in a technical stratospheric warming event is indeterminate. >>

Your dropping the ball, you should be down there chasing that beach snow and get a few brews too !

Really like what is going on the next few weeks in the HL. In a couple weeks we have this : We can see here what is going to transpire the second half of November as we move away from record strong vortex to date. Continued weakness moving forward....tropospheric NAM continues in a negative state Trends and associations with 02 - 03 winter, a decent QBO analog. And wow look at the 1960's Hey timelines are different, but wondering whether we are going to drop big time but just later. Here is a mention to 2009 regarding the weakest zonal wind for today's date ( Weakest zonal wind 10hPa 60N for todays date: 10.6m/s 2009 ) A speculative mention of the GloSea which has done well at certain times, this for Jan and Feb.

Exactly just throw me a bone! And yeah, I try not to think about 2016, I believe I measured about 17 inches, while Bob's hood had 5 feet :-)

The memorable high impact snowstorms of Jan 1996 and Feb 2003 was moisture moving into an established arctic air mass. Careful what you wish for though, as in my general area, the flow eventually rides from far over the Atlantic and warms the upper layers. Both the blizzards, 03 and 1996 changed over to sleet in my area while Philly hit something like 33 inches of snow. To score in a true sense with snow from start to finish we need ( or certain areas need ) that extreme -NAO which many times will steer that storm ENE versus NE. My best storm in the winter of 09-10 was actually the the December storm, which measured 26 inches, OMG, I long for that again!! The other two storms in the 09-10 winter did mix. The Feb 03 storm though was close to all snow event here, but eventually I read a 2,000 miles long of Easterly fetches warmed the upper layers, stopping me at about 23 inches, otherwise I would have surely hit well over 30 inches. Each high impact snowstorm varies. I love snowstorms!

I look forward to this winter forecast every year with much anticipation, it is up there with Isotherm and Benchmark's seasonal winter outlooks. Granted it is geared to NYC, but that really means little because you can see what is expected, and why for December, January and February. The thing that interested me was John saying the matching analogs to this winter are very slim. NYC Winter Forecast 2019-2020 By John Homenuk - November 11, 2019 356 0 We say it every year, but it’s worth repeating: Seasonal weather forecasting is one of the most challenging aspects of meteorology. It isn’t simply a guesstimate or an educated gamble. It is, instead, the product of months of research which typically begins at least two seasons prior. We’ve been piecing together ideas for this upcoming winter since Spring, and we are excited to present our findings to you. In that respect, we are hopeful to break down the components of the forecast in an easy to understand fashion in our NYC Winter Forecast. Instead of focusing on individual numerical indexes and values, we are going to try to paint a picture of the atmosphere and what it will be doing over the next few months – based on several global and hemispheric oscillations, conditions, and phenomena. This will lead us to the conclusions which we believe will be the guiding forces for us during the seasons ahead. There are three main pieces to a seasonal forecast, and while each year presents a different set of challenges, from a forecasting perspective these three pieces almost always remain engraved in the process. We must look at current conditions, analog years, and forecast guidance for the upcoming months to begin our forecast. The Summer of 2019 was characterized by a significant change in the higher latitudes of the atmosphere. From the arctic regions of the Pacific to the arctic regions of the Atlantic, large ridging became established. This degree of high latitude blocking is highly anomalous, especially when averaged out over a 3 monthly period. Most notably, perhaps, is the fact that this high latitude blocking also had not been observed in quite some time, especially over such a long duration. This summer, we recorded one of the longest -NAO periods on record. Such a change in the high latitudes certainly needs to be factored in to the Winter Forecast and we perused all of the available data to weight and rationalize our forecast properly. The role of ENSO in the upcoming Winter 2019-2020 Anticipated ENSO Conditions: Neutral to Weak El Nino ENSO conditions are one of they key drives to the Winter pattern. “Tropical forcing” refers to concentrated areas of showers and thunderstorms, otherwise referred to as convection, in meteorological regions of the tropics. This convection, most frequently observed in warm and moist climates, releases latent heat that then rises up into the atmosphere, forming ridges of higher atmospheric air pressure. The equatorial waters of the Pacific ocean that comprise the ENSO regions breed a great deal of convection, which then accordingly results in atmospheric ridging, and subsequently moves downstream, balancing the atmospheric regime. In a general sense, the more anomalous the positive sea surface temperature anomalies, the more convection that can then exert a stronger forcing mechanism on the adjacent regions of the atmosphere, reverberating throughout the globe. We anticipate weak-neutral to weak El Nino conditions during this Winter 2019-2020. These conditions were factored in to our Winter Forecast and our analogs were weighted and sorted accordingly. It is important to note that there is a great deal of variability among analogs as a result of the weak ENSO signal this year. The El-Nino that develops over the next few months may be of the Central Based nature – with the majority of the warming taking place in Central regions of the tropical Pacific. It is important to note that this is different from a “Modoki” El Nino – which by definition also features some cooling in the Eastern Tropical Pacific Ocean. Central Based El Nino events have a very different subset of effects when compared to basin-wide or especially Eastern Based El Nino Events. In general, they are cooler across the country in comparison, but particularly in the Eastern United States. There are still a few weeks to go before we will know with greater certainty how the ENSO conditions will evolve. Close monitoring of both the current conditions, subsurface warming and depth will be critical.T The Quasi-Biennial Oscillation (QBO) this winter Prediction: Descending easterly -QBO The QBO is a very important atmospheric index which monitors the quasi periodic oscillation between the equatorial zonal wind – from easterlies to westerlies. A negative QBO often supports higher latitude blocking and ridging, while a more positive QBO supports some resistance to high latitude blocking in those areas. Recently, a negative (easterly) QBO has been descending toward 30mb. This is an important factor in the Winter ahead, but it is uncertain how quickly the easterly QBO will continue to descend. We used a split analog package as there are only a limited number of QBO analogs which compare to the evolution so far this year. Other Factors (PDO, Solar Activity, etc) There are many other factors that go in to producing a Winter Forecast. We try to weight and balance our forecasts based on a variety of subjects. For example, this year the PDO (Pacific Decadal Oscillation) is at -0.66, but is displaying some characteristics more typical of a +PDO. We must weight our analogs accordingly. Solar activity is at a near 10-year minimum this year, which certainly will be factored in to the forecast as well. But all of these things tie back to the proper weighting of analogs to get an idea of exactly how the atmosphere is behaving. Analog years are an important component to winter forecast development. Looking back to past years that featured similar atmospheric progressions and conditions can offer us a peak into how things may evolve in the winter ahead. We can appropriately weight these based on our understanding of the atmosphere during those years and how it compares to current conditions. The usage of analog years in a Winter Forecast has been long debated and discussed. How much should a forecaster weigh what happened in the past against what is happening currently? How can we utilize past events when the atmosphere is almost certain to behave differently each time, especially given the difference in global weather when compared with weather events from the 1950’s and 1960’s? The answer lies in forecaster preference, and as is the case with most things, how a forecaster weights and blends different components into the forecast will have a huge impact on the end result. For us, each winter is different. This year in particular, the number of analog years that fit the set of conditions and the overall progression of the atmosphere is very slim. With that in mind, we decided to weight the analog years in our forecast very carefully, taking only the stronger year(s) and blending quickly downward toward the weaker analogs. We are comfortable with our analog composites that were presented and have factored them into our forecast as we typically do – simply a piece of the larger forecasting puzzle. When we take the individual pieces of research and compile them into one organized forecast, we can begin to see the ebbs and flows of the winter ahead – as they should be, according to our very best analogs and subset of current and past conditions. This winter, we are confident in our month-to-month composites and have indicated moderate to high confidence on each month. Below, we break down each months temperature and anticipated precipitation trends. While precipitation maps are not included (lower confidence) we discuss precipitation pattern and potential within each individual months breakdown. Please keep in mind, this is a NYC Winter Forecast, but we do discuss national trends and weather patterns as well! December 2019 December 2019 is expected to feature an expansive Southeast Ridge with warmer than normal temperatures across much of the Southeast United States. Warmth should also spread northward into the Mid-Atlantic States at times, as well as into New England. The majority of cold risks will be centered in the Northern Plains, where occasional cold shots are likely. It remains to be seen exactly how impressive these cold shots will be, and uncertainty is rather high – precluding any more impressive temperature anomaly forecasts there. The main area of uncertainty is over New England. The development of a -NAO by mid to late month could favor some colder temperatures in those regions, which may ultimately adjust the monthly average composites. However, we do not expect December to be an overly wintry month in the Northeast states at all. January 2020 Winter is expected to evolve more dramatically during the month of January, with the potential for further episodes of high latitude blocking on both the Pacific and Atlantic sides of the arctic. This should dislodge cold air southward into Canada and the United States. Below normal temperatures are expected on the monthly composites across the Northern Plains and parts of the Ohio Valley and Northeast. Periodic expansion of the Southeast Ridge should keep parts of that area above normal with temperatures even on a monthly basis. Snowfall is expected to average near or slightly above normal in the Midwest, Great Lakes and Northeast during January – which will feel active compared to the slow start in December. February 2020 As you may expect at this juncture, confidence is lowest in regards to February when compared to any other month. With that being said, our forecast carries forward the expectation that high latitude blocking will continue to remain prevalent during this month. Colder than normal temperatures are expected across the Great Lakes and Northeast as a result. Snowfall should again average near or slightly above normal in parts of the Great Lakes, Ohio Valley and Northeast, with a specific emphasis on New England where snowfall may end up solidly above average. Much of the Western USA is expected to be warm during this month as ridging remains stout. NYC Winter Forecast 2019-2020 Highlights and Summary We expect Winter 2019-2020 to start rather slowly, although there is a window for some wintry weather in very early December. The month will largely be characterized by bouts of warmth along the East Coast. The greatest potential for winter weather during December will exist across the Plains and Midwest. Gradually, as we move through January, Winter will pick up steam with a colder and snowier pattern becoming established. This may continue into February. Our current expectation is for temperatures to average near or slightly above average in NYC, with near or slightly above average snowfall. The worst of the Winter will likely be observed from mid to late January into early February. We wanted to take the time to thank you for reading our 2019-2020 Winter Forecast. The forecast was compiled at Empire Weather, LLC and New York Metro Weather, LLC in Fanwood, New Jersey from May of 2019 through October of 2019. The graphics were compiled by John Homenuk. Analog work and composition was completed by John Homenuk, Ed Vallee, Doug Simonian and Miguel Pierre. The presentation was compiled and edited by John Homenuk, Ed Vallee and Doug Simonian. Additional forecast feedback, commentary and production was provided by Steve Copertino. Each year, we are fortunate enough to produce and release a Winter Forecast both to clientele and to the public. We are grateful for the opportunity to share our forecast with as many people as we can – and we hope to deliver a forecast that provides detail, information and clarity. Here’s to a wonderful Winter ahead! PS – Don’t forget to check our daily forecast page here. John Homenuk John founded New York Metro Weather in 2008, and the website officially became an established LLC in 2012. Since completing his meteorology studies at Kean University, John has worked on both New York Metro Weather and Empire Weather to provide detailed and personalized weather forecast to the public and private sector.

Well, the slumber continues. And, if a few are correct, between the deep solar min lag effect and the well established E QBO early next winter should be frigid. Maybe even a change in the NAO domain that lasts several years. Space Weather Forecast - Discussion Issued: 2019 Nov 11 1230 UTC Prepared by the U.S. Dept. of Commerce, NOAA, Space Weather Prediction Center and processed by SpaceWeatherLive.com Solar activity 24 h Summary Solar activity was very low. No active regions with sunspots or Earth directed CMEs were observed. Forecast Solar activity is expected to continue at very low levels on 11-13 Nov. Energetic Particles 24 h Summary The greater than 2 MeV electron flux was at normal to moderate levels while the greater than 10 MeV proton flux remained at background levels. Forecast The greater than 2 MeV electron flux is expected to be normal to moderate on 11-13 Nov and the greater than 10 MeV proton flux is expected to persist at background levels throughout the forecast period. Solar Wind 24 h Summary Solar wind parameters were at background levels through about 11/0300 UTC when a gradual enhancement in parameters was observed. Increases in density, wind speed and total field indicated an anticipated CIR in advance of a negative polarity CH HSS became geoeffective. Shortly after 11/0900 UTC, wind speed peaked near 370 km/s, total field peaked at 11 nT while the Bz component reached a maximum southward extent of -11 nT.

Even "if" you buy into this, which based on most variables, persistence, and the cycle since 2000 which support Webb in his assumptions, then what about the timing. December could start out warm, and I put out there that we may be ahead of the typical response for December ( warm ) and hence return to a colder period in mid December versus in early Jan.

Man, if we can avoid that Pac jet from hell, like we had last winter that would be awesome!

Remarkable the general NH snow cover but also the lack of sea ice .

Fascinating data here on what does a cold November mean in terms of the period D, J and F . Brian is a PhD climatologist. Looking at the image we seem to be on the Southern edge of the moderate positive correlation shading. Last image is the data presented detrended. And here is the detrended data

Great outlook from @griteater, an educational read. Love the images and the associated content pertaining to what he interprets as the upcoming winter's main drivers. http://m.uploadedit.com/bbtc/1573380658807.pdf I really like the High latitude blocking diagram / chart at the end of his presentation. That is pretty cool, very concise and right to the point. Good luck grit. Please drop in here if you like, and provide your thoughts if you ever see a high impact time period coming up. I know you are SE forum based, but your posts are always valuable. Best of luck with your forecast !

Awesome image below, and on top the current disconnect between the stratosphere and the troposphere , Hugo is a reliable source of great information on this topic.

The more I visit this site the more I love it , plus Simon updated the site with this new data, which I have not seen anywhere else ( lower stratospheric anomalies ) : New product online at https://simonleewx.com/polar-vortex-forecasts/… GEFS forecasts of tercile anomaly categories of 100 hPa 60°N zonal-mean zonal wind. These lower stratospheric anomalies are important for influencing the what happens in troposphere, and are often more relevant than 10 hPa. Polar Vortex Forecasts All charts are updated once daily between 8:30-10:30 AM London time. Please feel free to share any images from this site on social media or elsewhere. 00Z GFS 0.5° & GEFS 1.0° 10 hPa 60°N ensemble plume 00Z GFS 0.5° 10 hPa 60°N forecast evolution White crosses indicate a strong vortex event (>41.2 m/s) following Tripathi et al. 2015. CFSv2 1.0° 10 hPa 60°N bias-corrected ensemble plume This is produced by taking the 4-member ensembles from 00, 06, 12 and 18Z yesterday and combining into a 16-member ensemble, out to 45 days. The bias is calculated as the difference between the 1999-2009 hindcasts (available from the S2S database) and ERA-Interim reanalysis. The CFSv2 has a significant bias toward a weak vortex, especially for forecasts launched in early winter, so accounting for this drift is necessary. It should be noted that a simple linear bias correction does not necessarily solve the problems produced by the bias, as the bias can interfere with the model dynamics. 00Z GFS 0.5° & GEFS 1.0° 1000 hPa Northern Annular Mode (NAM) ensemble plume This is calculated using the method of Gerber and Martineau (2018) using standardized anomalies of 65-90°N geopotential height (with respect to 1979-2018 ERA-Interim climatology) with the global mean anomaly removed. I thank Zac Lawrence for calculating the filtered ERA-Interim climatology used here. 00Z GEFS 1.0° 100 hPa 60°N tercile categories The tercile-category anomaly of the lower-stratospheric polar vortex, defined by the 100 hPa 60°N zonal-mean zonal wind, has been used as a diagnostic for the behaviour in the ‘coupling layer’ between the stratosphere and troposphere, i.e. the level in the stratosphere where circulation anomalies are important for influencing tropospheric weather regimes (e.g. Charlton-Perez et al. 2018, Lee et al. in review). The chart below shows the percent of GEFS members in each tercile anomaly category, based on daily 1979-2018 ERA-5 climatology. 00Z GFS 0.5° & GEFS 1.0° Scandinavia-Greenland dipole ensemble plume This dipole pattern, defined in Lee et al. (2019) as the MSLP difference between a grid box over Scandinavia and a grid box over north-east Greenland, can be used as a diagnostic of anticyclonic wave breaking in the north-east Atlantic which can enhance vertically-propagating wave activity and weaken the stratospheric polar vortex. In the paper, we use 40 hPa as a threshold (strong Scandinavia high + deep Greenland low) as this is similar to what occurred before the February 2018 major SSW, but values above 30 hPa are noteworthy.

Soon we will know how smart the seasonal models are with the NAO call. The post by Tony is interesting. Of note, if you click and close up on the image I do tend to see what Isotherm mentioned and someone else at 33andrain, a deeper NAO after the bottom of the solar min. Also, not related to this post by Tony , but read as well, next winter we reap the benefits of an established Easterly QBO . Personally I have seen the cycles go slower and then other times quicker. DT has something online that when the QBO is -10 to -20 it corresponds to a very cold Eastern winter. As Isotherm mentioned as well we are not dropping fast enough to reap the benefits of the changing QBO in the early winter , but will tend to at least increase the odds it helps us when we get to Feb and March

Of interest ....... hopefully it has a clue. Or , another way to look at it ..... Bob > CFSv2

Looking good, I have seen worse

A little twist here on time lines . When I watched a great webinar from BAMMWX a week ago they talked about how the PV was ahead in the progression versus some other years in their analog package and research. Also, the Siberian High is robust and off to a good start due to the abundance of Siberian snowfall. So, taken a step further everything happened so quickly , including the ramp up of the PV we are indeed ahead of historical timetables. ( per Webb - ahead by a month or so ) It is natural for the PV wanting to get stronger just as it is typical for it to undergo pressure and disruptions, which happens every year. The players are starting to work on the PV . Of course there is the lag to take into account. There are many outcomes possible in the next several weeks. HM's post for example. ( may not have to wait for a top down ) This post below is of interest and touches on this very thing.

Agreed. Seems Isotherm's sticking point, or one of several, was the PDO and the general Pac. ( And, I do acknowledge he did say Feb and March might be good for our area, but not good enough to get us above his snowfall projections ) I hope we get the changes you are talking about. It would be ironic if we time the STJ and the cold even for a week correctly, and then one storm alone can have a huge impact on the seasonal snowfall totals . aka Jan 2016.

I am surprised he posted something "positive " . Most of the things recently were negative. Being in the South I think, and maybe he is just tired of the warmth. Grown a little tired of hearing him focus on the roll forward MJO and the warmth coming for December. I will take a -NAO in December though.

Some decent thoughts here about the NAO from Webb, and what may happen. Plus, a quick one from HM on the same topic.

Check this out, really impressive.

There are signs that a real - NAO may get going to extend the colder pattern in the NE later in November. There always has been talk that later November/early December it could occur. Looks of retrogression in the pattern along with several indicators such as the MJO, Aleutian low, Scand block.

Something else to ponder. A +PDO versus the Victoria mode. You can see the image at the bottom for a representation of the associated SST anomaly . I need to research this more. Maybe Bob can chime in on this. To me the Victoria mode looks like a + PMM a little . I refer you to this https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2014JD022221 The Victoria mode (VM) represents the second dominant mode (empirical orthogonal function, EOF2) of North Pacific variability, independent of the Pacific Decadal Oscillation and is defined as the EOF2 of SST anomalies in the North Pacific poleward of 20°N. The present study indicates that the VM is closely linked to the development of El Niño–Southern Oscillation (ENSO). The VM may effectively act as an ocean bridge (or conduit) through which the extratropical atmospheric variability in the North Pacific influences ENSO.