donsutherland1

Reminder that beyond about 2 weeks, extended range models have little skill. In just one day, here's how the ECMWF weeklies changed for the January 1-8, 2024 timeframe.

A moderating trend will commence tomorrow. Showers could affect the region late in the day or Saturday. The ENSO Region 1+2 anomaly was +2.0°C and the Region 3.4 anomaly was +2.1°C for the week centered around November 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +2.22°C and the ENSO Region 3.4 anomaly has averaged +1.80°C. A basinwide El Niño event is ongoing. El Niño conditions will likely continue to strengthen into the early winter. Should the ENSO Region 1+2 and 3.4 anomalies remain at or above +1.00°C in December, which is likely, and should the PDO remain negative, there is a single past case (1950-2022) with similar ENSO/PDO conditions: December 1972. The SOI was -0.89 today. The preliminary Arctic Oscillation (AO) was -2.468 today. On November 27 the MJO was in Phase 3 at an amplitude of 0.555 (RMM). The November 26-adjusted amplitude was 0.824 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a cooler than normal November (1991-2020 normal). November will likely finish with a mean temperature near 46.4° (1.5° below normal). That would be New York City's coldest November since November 2019.

No. High geomagnetic activity tends to favor a positive NAO or lack of Atlantic blocking. https://link.springer.com/content/pdf/10.1007/s11200-014-0508-z.pdf

I agree. It's definitely not going to be a "blowtorch" this time around. The East will probably be somewhat warmer than normal in most places. Nothing like 2015 is remotely on the table as far as I can see. Even 1994-type warmth seems unlikely. Colder prospects late in the month are possible (showing up on some of the extended guidance).

For those who are interested in December outcomes in the East based on the MJO's being predominantly in Phases 4 or 5 in early December (December 1-10):

386 days.

Yes it is. Sadly, I think the Park will break that record, too.

Today was blustery and winterlike with highs finishing in the upper 30s and lower 40s. Baltimore, Bridgeport, Islip, New York City, Newark, and Philadelphia were among locations seeing their first snow flurries of the season. Tomorrow be partly sunny but unseasonably cold. Temperatures will again peak mainly in the 30s in much of the region. A moderating trend should commence on Thursday. The ENSO Region 1+2 anomaly was +2.0°C and the Region 3.4 anomaly was +2.1°C for the week centered around November 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +2.22°C and the ENSO Region 3.4 anomaly has averaged +1.80°C. A basinwide El Niño event is ongoing. El Niño conditions will likely continue to strengthen into the early winter. Should the ENSO Region 1+2 and 3.4 anomalies remain at or above +1.00°C in December, which is likely, and should the PDO remain negative, there is a single past case (1950-2022) with similar ENSO/PDO conditions: December 1972. The SOI was -1.72 today. The preliminary Arctic Oscillation (AO) was -1.042 today. On November 26 the MJO was in Phase 3 at an amplitude of 0.824 (RMM). The November 25-adjusted amplitude was 1.015 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a cooler than normal November (1991-2020 normal). November will likely finish with a mean temperature near 46.3° (1.6° below normal). That would be New York City's coldest November since November 2019.

There was a passing snow flurry in the Bronx.

Yes. Central Park reported the lowest amount (0.9” vs JFK’s 1.0” on February 27).

Through November 27, both New York City and Philadelphia are continuing their longest streaks on record during which less than 1" daily snowfall was measured.

Tomorrow and Wednesday will be partly sunny but unseasonably cold. Temperatures will peak in the 30s tomorrow and Wednesday in much of the region. Flurries are possible, especially tomorrow. A few areas outside of New York City could see a heavier snow shower that could briefly coat the ground. A moderating trend should commence on Thursday. The ENSO Region 1+2 anomaly was +2.0°C and the Region 3.4 anomaly was +2.1°C for the week centered around November 22. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +2.22°C and the ENSO Region 3.4 anomaly has averaged +1.80°C. A basinwide El Niño event is ongoing. El Niño conditions will likely continue to strengthen into the early winter. Should the ENSO Region 1+2 and 3.4 anomalies remain at or above +1.00°C in December, which is likely, and should the PDO remain negative, there is a single past case (1950-2022) with similar ENSO/PDO conditions: December 1972. The SOI was not available today. The preliminary Arctic Oscillation (AO) was -0.317 today. On November 25 the MJO was in Phase 2 at an amplitude of 1.015 (RMM). The November 24-adjusted amplitude was 1.141 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a cooler than normal November (1991-2020 normal). November will likely finish with a mean temperature near 46.3° (1.6° below normal). That would be New York City's coldest November since November 2019.

Latest NAO forecast shows the NAO going positive in the extended range. The AO remains negative. Were both to go positive, that would favor an even warmer outcome than is currently forecast.

It should be noted that even as there is large variability in the percentage of days during which the MJO is in Phases 4-6 during El Niño events, the percentage has been trending higher during the winter months. The trend is based on the 16 El Niños for which daily MJO data is available.

Final Outcomes:

It’s not an analog but an illustration of how few winters there have been with an ENSO Region 3.4 anomaly of 1C or above and a negative PDO. This December could be unique as there should be more blocking than during any of those three cases.

Those weren’t great winters up here. Parts of the South from Georgia into the Carolinas had a historic snowstorm during February 1973.

It’s developing. We’ll need it to be sustained. If the Pacific can then improve, we should be in business for potential wintry outcomes. That’s still beyond the skillful range of the guidance. Hopefully, things will evolve to allow us to break the ongoing snow drought.

"Hot" off the CPC press:

It is, but El Niño winters are often backloaded to January and February.

Hopefully, January and February will break the snow drought in a big way.

A developing storm will bring rain to the region tonight into early tomorrow. Most areas should see 0.50"-1.00" of rain. Areas on eastern Long Island into eastern New England could see higher amounts. In the wake of the storm, Monday will turn partly cloudy, breezy, and mild. However, colder air will overspread the region and temperatures could fall during the afternoon hours. Tuesday and Wednesday will be partly sunny but unseasonably cold. Flurries are possible, especially on Tuesday. A moderating trend should commence during the middle of the week. The ENSO Region 1+2 anomaly was +2.0°C and the Region 3.4 anomaly was +1.9°C for the week centered around November 15. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +2.27°C and the ENSO Region 3.4 anomaly has averaged +1.70°C. El Niño conditions will likely continue to strengthen into the early winter as the current East-based event completes its evolution into a basinwide El Niño. Should the ENSO Region 1+2 and 3.4 anomalies remain at or above +1.00°C in December, which is likely, and should the PDO remain negative, there is a single past case (1950-2022) with similar ENSO/PDO conditions: December 1972. The SOI was +10.18 today. The preliminary Arctic Oscillation (AO) was -0.121 today. On November 24 the MJO was in Phase 2 at an amplitude of 1.141 (RMM). The November 23-adjusted amplitude was 1.140 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a cooler than normal November (1991-2020 normal). November will likely finish with a mean temperature near 46.0° (1.9° below normal). That would be New York City's coldest November since November 2019.

Recently, Philadelphia set a new record for its longest streak without daily snowfall of 1" or more. Elsewhere existing records include: Allentown: 368 days Atlantic City: 715 days Baltimore: 672 days New York City: 651 days (ongoing) Richmond: 725 days Trenton: 664 days Washington, DC: 788 days Wilmington, DE: 756 days Note: All numbers are through today, as no snowfall is expected.

December 2023 appears poised to move into little charted, if not uncharted territory for an El Niño event with a Region 3.4 anomaly of +1° or above and a negative PDO. None of the three cases since 1950 featured a predominantly negative Arctic Oscillation (AO) or North Atlantic Oscillation (NAO). The possibility of such an outcome exists this time around, possibly due to ongoing marine heatwaves that have distorted the effects of the ongoing El Niño to date. With the AAM forecast to go positive during the first week of December, there is also the risk of the development of a more typical El Niño hemispheric pattern. During that time, the MJO could approach or reach the warmer Maritime Continent phases. Some lessons from the past might be applicable, especially when one considers the periods of blocking that occurred during those past three cases (December 15-18, 1972 and December 1-6, 1991): 1. Cold could be nearby or present when Atlantic blocking is ongoing. As the climate has warmed since these cases, especially 1972, areas of cold could be less expansive and less impressive than they were during the December 1972 and December 1991 blocking episodes. Overall, December 2023 could be colder relative to normal than the 1972, 1991, and 1994 cases, but not necessarily colder than normal, as blocking should be present for a longer period of time than during those cases. 2. Monthly snowfall will likely be linked to the presence of the blocking. All of December 1991's 0.7" snowfall in New York City occurred when the AO and NAO were negative. Total snowfall for December 1972 and 1994 came to a trace. Given historic experience with the three El Niño cases above, keeping in mind the tiny sample size, there remains at least some risk that the blocking forecast for early December could break down for the second half of the month.

The latest numbers for the week ahead: