donsutherland1

The idea of an imminent SSW/MSW event is a high-confidence one. However, there is often a tendency to treat forecast developments (“SSW → PV split → EPO-/WPO-/AO-/PNA- → brutal NE weather”) as if it were an inevitable, linear, cause-and-effect chain. If such logic were reliable, forecasting accuracy at multi-week stages would be high. That isn't the case. I personally believe that there will be an increase in wintry effects, especially from near mid-December into at least late December based on typical 1-3 week lags and the currently forecast teleconnection evolution. That's my baseline thinking at present. However, that thinking isn't cast in stone. Reality is messier. For example, not every SSW leads to a prolonged deep AO-. Not every AO- period results in severe cold and/or excessive snowfall. From this far out, model skill is poor to non-existent on critical synoptic factors e.g., future storm tracks, the emergence of North Pacific jet streaks, exact ridge-trough placement, etc. A bad pattern coupled with a well-timed phase can produce a big snowstorm; a great pattern but badly-timed phases or absence of shortwaves can result in a lack of snowfall. Seemingly favorable ensemble means can also disguise large differences among ensemble members. Clusters can provide insight into some scenarios. Here are the forecast 500 mb anomalies at 360 hours: Here are the latest 500 mb and 1000 mb ECMWF clusters: 500 mb: 1000 mb: For now, potential is on the table. But nothing is locked in, just yet, in terms of specific details.

A weak system could bring a few scattered rain and/or snow showers tonight into tomorrow. No measurable snowfall is likely in New York City. Since daily snowfall and temperature records were kept, just 1 out of 55 (1.8%) systems with minimum temperatures of 38° or above had measurable snowfall in Central Park. Afterward, tomorrow will be another cool day with highs topping out in the 40s. Below normal temperatures will prevail through at least Thursday. Highs will be mainly in the middle and upper 40s in New York City with lows in the middle and upper 30s. A milder pattern will likely develop during the latter part of the week. Some rain or rain showers are possible. Once in place, the milder pattern could continue for a week or longer. Meanwhile, today will be Central Park's 1,389th consecutive day without daily snowfall of 4" or more. The record of 1,394 days was set during February 22, 1929 through December 16, 1932. That stretch ended with 6.7" daily snowfall on December 17, 1932. The ENSO Region 1+2 anomaly was -0.7°C and the Region 3.4 anomaly was -0.7°C for the week centered around November 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.16°C and the ENSO Region 3.4 anomaly has averaged -0.65°C. La Niña conditions will likely continue through at least mid-winter. The SOI was +27.87 today. The preliminary Arctic Oscillation (AO) was -1.686 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 61% probability that New York City will have a cooler than normal November (1991-2020 normal). November will likely finish with a mean temperature near 47.4° (0.6° below normal). Supplemental Information: The projected mean would be 0.3° below the 1981-2010 normal monthly value.

I'm well. I hope you're doing well. Hopefully, this coming winter will produce a lot of snowy days. It would be nice to turn back the clock to the kind of winters that made this site grow.

The Earth would typically need to see a shift of 0.1° (about 7 miles) or more for an impact on its climate through changes in solar insolation. The reported shift is far less than that. It's essentially meaningless from a climate standpoint.

The following morning:

Tomorrow will be another cool day with highs topping out in the 40s. Below normal temperatures will prevail through at least Wednesday and possibly Thursday. Highs will be mainly in the middle and upper 40s in New York City with lows in the middle and upper 30s. A milder pattern will likely develop during the latter part of the week. Some rain or rain showers are possible. Once in place, the milder pattern could continue for a week or longer. Meanwhile, today will be Central Park's 1,388th consecutive day without daily snowfall of 4" or more. The record of 1,394 days was set during February 22, 1929 through December 16, 1932. That stretch ended with 6.7" daily snowfall on December 17, 1932. The ENSO Region 1+2 anomaly was -0.7°C and the Region 3.4 anomaly was -0.7°C for the week centered around November 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.16°C and the ENSO Region 3.4 anomaly has averaged -0.65°C. La Niña conditions will likely continue through at least mid-winter. The SOI was +19.47 today. The preliminary Arctic Oscillation (AO) was -2.297 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 62% probability that New York City will have a cooler than normal November (1991-2020 normal). November will likely finish with a mean temperature near 47.5° (0.5° below normal). Supplemental Information: The projected mean would be 0.2° below the 1981-2010 normal monthly value.

Latest PNA forecast for the closing days of November. This is why one shouldn't expect a sudden rush of cold into the East, even as colder air should be building in Canada and the western U.S.

ENSO Region 1+2 has see a recent, fairly sharp cooling. This decline is in line with the ECMWF Seasonal Forecast from November 1. As a result, the development provides a measure of confidence that its forecast is on track at this point.

I hope it will be better than I expect.

In conjunction with its annual Holiday train show, the New York Botanical Garden is running a feature called "the Nightmare Before Christmas Light Trail." Some of these characters could well have been taken from this thread. The Southeast Ridge Waiting for Winter

Some virga from late this afternoon:

A colder air mass is now overspreading the region. The wind will diminish tonight. Below normal temperatures will prevail through at least Wednesday and possibly Thursday. Highs will be mainly in the middle and upper 40s in New York City with lows in the middle and upper 30s. A milder pattern will likely develop during the latter part of the week. Some rain or rain showers are possible. Once in place, the milder pattern could continue for a week or longer. If so, that could tip the odds toward a warmer than normal monthly mean temperature. Meanwhile, today will be Central Park's 1,387th consecutive day without daily snowfall of 4" or more. The record of 1,394 days was set during February 22, 1929 through December 16, 1932. That stretch ended with 6.7" daily snowfall on December 17, 1932. The ENSO Region 1+2 anomaly was -0.2°C and the Region 3.4 anomaly was -0.7°C for the week centered around November 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.07°C and the ENSO Region 3.4 anomaly has averaged -0.55°C. La Niña conditions will likely continue through at least mid-winter. The SOI was +8.20 today. The preliminary Arctic Oscillation (AO) was -1.552 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 53% probability that New York City will have a cooler than normal November (1991-2020 normal). November will likely finish with a mean temperature near 47.7° (0.3° below normal). Supplemental Information: The projected mean would be at the 1981-2010 normal monthly value.

So far, LaGuardia has had a 47 mph gust and Newark has had a 45 mph gust.

Yes. A PNA- is one of my baseline assumptions for December. The combination of EPO-/WPO-/AO- with a PNA- isn't all that bad based on the composite values and the majority of dates in the clusters for such a setup. There should be some intrusions of cold air into the East with perhaps some snowfall prospects. I could see December finishing with 2"-4" monthly snowfall in the NYC area (much more in the Great Lakes Region, especially Detroit to Toronto). For now, I don't think a blockbuster snowy month is in order. I don't think we'll see anything close to December 2010-type cold. I do believe that the EPO-/WPO- should thwart the possibility of a top 10 warmest December. Given the timeframe involved, changes are still possible.

From the Bronx: