donsutherland1

Cooler air is now pouring into the region. The weekend will turn somewhat cooler. No exceptionally cold or warm weather appears likely for the first week of astronomical winter. In terms of precipitation, some rain or snow showers are possible on Tuesday. The closing week of December could experience periodic warmer and cooler days. It now appears that the cooler anomalies will persist mainly in central and northern New England. The probability that December 2025 will have a maximum monthly temperature below 60° has continued to increase. The last time that happened was in 2019 when the monthly high was 58°. If 2025 has a monthly high below 60°, that would be only the fifth such occurrence since 2000 (2003, 2004, 2005, and 2019 are the cases since 2000). The ENSO Region 1+2 anomaly was -0.3°C and the Region 3.4 anomaly was -0.7°C for the week centered around December 10. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.33°C and the ENSO Region 3.4 anomaly has averaged -0.67°C. La Niña conditions will likely continue through at least mid-winter. The SOI was -1.19 today. The preliminary Arctic Oscillation (AO) was +2.327 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 98% probability that New York City will have a cooler than normal December (1991-2020 normal). December will likely finish with a mean temperature near 34.3° (4.8° below normal). Supplemental Information: The projected mean would be 3.1° below the 1981-2010 normal monthly value.

In addition to high winds and heavy rainfall, today was a day of record temperatures in many parts of the Northeast.

For December through the first half of February, that's definitely the case. Big PNA- snowstorms are a rarity. However, once one gets to the second half of February, the PNA- is better (wave lengths are shortening).

Numerous records have been tied or broken through 11 am:

I agree. I've made some horrific errors. They were good opportunities for learning/improvement. I've never deleted any of my posts, good or bad.

I've bumped this post, because the original embedded tweets calling for a PNA+ in December were deleted (not by @stadiumwave). It's ok to be wrong in a field where there are no crystal balls and variables typically have low coefficients of determination. These low coefficients of determination increase complexity and raise risks of oversimplification. Error is inescapable. It's also ok to change one's thinking. Indeed, the information on how one's thinking evolves can provide insight and also learning opportunities. IMO, it's not ok to simply delete posts to obscure one's errors. Indeed, it is bad practice. That someone I greatly respect and who has done pioneering work on the MJO engaged in this bad practice makes it all the more disappointing. Although the original post is gone, at least some people remember that the prediction made (and one I questioned here) was for a predominantly positive PNA in December. The argument was that the base state did not favor a PNA-. Probably not too surprisingly, the poster's question was ignored. Responding to it would have acknowledged the original position that apparently was deleted.

Recent gusts: Bridgeport: 44 mph Farmingdale: 61 mph Islip: 60 mph JFK Airport: 55 mph

Bridgeport has now received 0.67" of rain today. That breaks its daily precipitation record for December 19 of 0.64" from 1948.

Central Park received 0.44" of rain in the past hour. That breaks the highest hourly figure for December 19th. The old record was 0.32" from 1934.

White Plains has also broken its daily record while New Haven has tied its record. More could fall before temperatures start to fall later this morning.

Just a brief note, the probability that the warmth will break through into the northern Mid-Atlantic and southern New England areas to close December has increased in recent days. The widespread warmth elsewhere in much of the CONUS and cold in NW Canada and Alaska remain intact. The forecast EPO+/PNA- seems sufficiently strong to offset the combination of a neutral AO and negative NAO even into parts of the Northeast now. Previously, the EPO was forecast to be mainly negative for the close of December. EPS from Wednesday 0z: EPS from Today 0z:

Negativity about this winter seems to be rising. There seems to be a growing focus on the time snow does not fall. I choose to focus on the positive. I savor every snowfall, even the small ones. Sunday's snowfall provided some scenes that can be used for some of the custom Holiday e-cards will share with colleagues at work. One example:

A soaking rain will develop tonight with a storm total 0.50"-1.50" rain likely across the region by the time the storm pulls away late tomorrow. The wind could also gust past 50 mph producing some coastal flooding and beach erosion. It will also be unseasonably mild tomorrow with highs reaching the lower and middle 50s. Behind the storm, the weekend will turn somewhat cooler. No exceptionally cold or warm weather appears likely for the first week of astronomical winter. The probability that December 2025 will have a maximum monthly temperature below 60° has continued to increase. The last time that happened was in 2019 when the monthly high was 58°. If 2025 has a monthly high below 60°, that would be only the fifth such occurrence since 2000 (2003, 2004, 2005, and 2019 are the cases since 2000). The ENSO Region 1+2 anomaly was -0.3°C and the Region 3.4 anomaly was -0.7°C for the week centered around December 10. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.33°C and the ENSO Region 3.4 anomaly has averaged -0.67°C. La Niña conditions will likely continue through at least mid-winter. The SOI was -2.23 today. The preliminary Arctic Oscillation (AO) was +2.676 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 99% probability that New York City will have a cooler than normal December (1991-2020 normal). December will likely finish with a mean temperature near 33.9° (5.2° below normal). Supplemental Information: The projected mean would be 3.5° below the 1981-2010 normal monthly value.

Thank you. I've never seen a link.

I wasn't aware of that disparity. That's a pretty sizable change.

Very interesting archived forecast. Is this information publicly-accessible and, if so, do you have a link?

For Baltimore:

It will be interesting to see how things evolve. Since 1980, December PNA- cases have been followed by January PNA+ cases. Prior to 1980, December PNA- cases were generally followed by January PNA- cases. It is possible that the less stable PNA state is, at least in part, a result of Arctic amplification.

Here's some data for NYC for January and March (1980-2025):

I suspect that when it comes to snowstorms in parts of the Southeast, more is involved than the pattern itself. Synoptic details are critical and outweigh the teleconnections. One sees a similar outcome in the spring in the Middle Atlantic region as wave lengths shorten and the state of the teleconnections becomes less important.

Perhaps. However, the December 2010 blizzard was a Miller B system. Baltimore: Trace Boston: 18.2" Islip: 14.2" New York City: 20.0" Newark: 24.2" Philadelphia: 12.4" Washington, DC: 0.4" Wilmington, DE: 3.5"

While the AO and NAO are looking good on the latest GEFS, the PNA is not.

In general, a PNA- pattern results in lighter snowfalls in the New York City area and northern Mid-Atlantic. The Boxing Day blizzard is a notable exception and the only KU snowstorm during December when the PNA was negative.

This morning, the low temperature at Central Park was 36° while the lows at Bridgeport and White Plains were 24° and 25° respectively. That is the largest difference in low temperatures between Central Park and Bridgeport and Central Park and White Plains this month. The last time these differences were matched or exceeded was November 25, 2025 when Central Park had a low of 46°, Bridgeport had a low of 34°, and White Plains had a low of 35°.