donsutherland1

Congratulations, NJwx85.

Mild weather will prevail through the remainder of the month. The warmth will crest from tomorrow through Thursday. High temperatures will top out in the lower and perhaps middle 50s during that time in New York City. Washington, DC will likely see highs reach the lower and middle 60s. Boston could reach or exceed 50° at least once. Afterward, high temperatures will cool somewhat to the middle and upper 40s to end February. No meaningful threats for a moderate or larger snowfall in the New York City area are likely through the remainder of February. There remain indications that a major pattern re-alignment could take place starting in the first week of March bringing an end to a persistently cold regime that has predominated through most of the winter. By mid-month, a sustained warmer than normal pattern could be in place. The pattern change will likely follow a brief but fairly sharp cold shot. A powerful PNA ridge is currently in place. Historical experience suggests that the presence of such a ridge at this time of year has been followed by the absence of major snowfalls in the New York City area. The PNA reached +1.500 on February 19th and remained at or above +1.500 through February 23rd. In all 12 years that saw the PNA reach +1.500 or above on February 15 or later since 1950, the remainder of winter saw no 10" or greater snowstorms. If historic experience holds true yet again, that would make the Winter 2024-2025 the fourth consecutive winter without a 10" or above snowstorm in New York City. The last time that happened was during Winter 2016-2017 through Winter 2019-2020. Most of the 12 winters cited above went on to see some additional measurable snowfall with a few seeing a 6"+ storm. The ENSO Region 1+2 anomaly was +0.9°C and the Region 3.4 anomaly was -0.3°C for the week centered around February 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.03°C and the ENSO Region 3.4 anomaly has averaged -0.65°C. La Niña conditions have peaked and are beginning to fade. La Niña conditions will likely persist into the start of spring. The SOI was +11.58 today. The preliminary Arctic Oscillation (AO) was +2.936 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 98% probability that New York City will have a colder than normal February (1991-2020 normal). February will likely finish with a mean temperature near 34.2° (1.7° below normal).

That might be a final warming event. We'll see how it evolves.

Final outcomes: The ECMWF weeklies did badly with precipitation anomalies and the EPS snowfall forecast was about as bad as it could have been.

Mild weather will prevail through the remainder of the month. That will cut the once impress monthly cold anomaly in New York City, but February will still finish solidly below normal. The warmth will crest during the Tuesday through Thursday period. High temperatures will top out in the lower and perhaps middle 50s during that time in New York City. Washington, DC will likely see highs reach the lower and middle 60s. Boston could reach or exceed 50° at least once. Afterward, high temperatures will cool somewhat to the middle and upper 40s to end February. No meaningful threats for a moderate or larger snowfall in the New York City area are likely through the remainder of February. There remain indications that a major pattern re-alignment could take place starting in the first week of March bringing an end to a persistently cold regime that has predominated through most of the winter. By mid-month, a sustained warmer than normal pattern could be in place. The pattern change will likely follow a brief but fairly sharp cold shot. A powerful PNA ridge is currently in place. Historical experience suggests that the presence of such a ridge at this time of year has been followed by the absence of major snowfalls in the New York City area. The PNA reached +1.500 on February 19th and currently stands at a preliminary value of +1.648. In all 12 years that saw the PNA reach +1.500 or above on February 15 or later since 1950, the remainder of winter saw no 10" or greater snowstorms. If historic experience holds true yet again, that would make the Winter 2024-2025 the fourth consecutive winter without a 10" or above snowstorm in New York City. The last time that happened was during Winter 2016-2017 through Winter 2019-2020. Most of the 12 winters cited above went on to see some additional measurable snowfall with a few seeing a 6"+ storm. The ENSO Region 1+2 anomaly was +0.9°C and the Region 3.4 anomaly was -0.3°C for the week centered around February 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.03°C and the ENSO Region 3.4 anomaly has averaged -0.65°C. La Niña conditions have peaked and are beginning to fade. La Niña conditions will likely persist into the start of spring. The SOI was +4.42 today. The preliminary Arctic Oscillation (AO) was +2.194 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 95% probability that New York City will have a colder than normal February (1991-2020 normal). February will likely finish with a mean temperature near 34.2° (1.7° below normal).

For perspective (noting all the comments about Winter 2024-2025's outcome), NYC will very likely finish with a seasonal mean temperature of between 34.4° and 34.8°. Here's how the winter would rank against recent winters, all winters, and the three most recent seasonal baselines.

There was at least some heavy snow in the New York City area, but the biggest snows were in New England. Heavy snow reached New York City and Boston by the early morning of February 22. The blizzard intensified in southern New England, dropping 18 inches on Hamden, Connecticut.

It's really impressive.

Yes. Reed Timmer's group.

The week ahead outlook:

The thermometer topped out at 39° today in Central Park. It will turn even milder tomorrow with the temperature reaching or exceeding 40°. This milder weather will then continue all of next week. The middle of next week could become quite mild with the mercury reaching 50° or above in New York City. Washington, DC could see highs reach 60° or above. Afterward, high temperatures will cool somewhat to the middle and upper 40s to end February. No meaningful threats for a moderate or larger snowfall in the New York City area are likely through the remainder of February. There remain indications that a major pattern re-alignment could take place starting in the first week of March bringing an end to a persistently cold regime that has predominated through most of the winter. The pattern change will likely follow a brief but fairly sharp cold shot. A powerful PNA ridge is currently in place. Historical experience suggests that the presence of such a ridge at this time of year has been followed by the absence of major snowfalls in the New York City area. The PNA reached +1.500 on February 19th and currently stands at +1.750. In all 12 years that saw the PNA reach +1.500 or above on February 15 or later since 1950, the remainder of winter saw no 10" or greater snowstorms. If historic experience holds true yet again, that would make the Winter 2024-2025 the fourth consecutive winter without a 10" or above snowstorm in New York City. The last time that happened was during Winter 2016-2017 through Winter 2019-2020. Most of the 12 winters cited above went on to see some additional measurable snowfall with a few seeing a 6"+ storm. The ENSO Region 1+2 anomaly was +0.9°C and the Region 3.4 anomaly was -0.3°C for the week centered around February 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.03°C and the ENSO Region 3.4 anomaly has averaged -0.65°C. La Niña conditions have peaked and are beginning to fade. La Niña conditions will likely persist into the start of spring. The SOI was +1.30 today. The preliminary Arctic Oscillation (AO) was +1.502 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 93% probability that New York City will have a colder than normal February (1991-2020 normal). February will likely finish with a mean temperature near 33.9° (2.0° below normal).

Some updates on last week’s thoughts: 1. A storm brought moderate to significant precipitation to the northeastern U.S. during February 15-16. Precipitation amounts included: Albany: 1.08”; Boston: 1.79”; New York City: 1.08”; and, Philadelphia: 0.94”. Philadelphia saw somewhat less precipitation than the 1”-2” cited. 2. The February 17-21 period was much colder than normal in Des Moines, Kansas City, and Omaha. Their respective anomalies were: Des Moines: 26.4° below normal; Kansas City: 29.9° below normal; and, Omaha: -30.8° below normal . The coldest temperatures in those three cities were: Des Moines: -11°; Kansas City: -10° on February 20 (old record: 2°, 1918; Kansas City also set a daily record of -4° on February 19); and, Omaha: -15° on February 20 (old record: -11°, 1918). Chicago had a low temperature of -5° on February 18. The last time Chicago saw a temperature at least as cold during the second half of February was February 28, 2015 the temperature fell to -10°. In addition, Bismarck had a low temperature of -39° on February 18 (old record: -37°, 1910). That was Bismarck’s coldest temperature since January 15, 2009 when the thermometer dipped to -44°. Bismarck recorded lows of -35° on February 17 and -39° on February 18. The last time Bismarck had two low temperatures of -30° or colder during the second half of February was 1936 when the city saw two consecutive lows below -40°. Bismarck’s high temperature of -11° on February 17 was the coldest high temperature during the second half of February since February 18, 1966 when the temperature also topped out at -11°. 3. A significant (6” or more) snowstorm blanketed the Lower Mid-Atlantic Region during February 19-20. The significant snowfall was confined to parts of North Carolina and southeast Virginia. Norfolk picked up 11.0”, its biggest snowfall since December 26-27, 2010 when 13.4” accumulated. Significant snow is possible but not assured in Baltimore, Philadelphia, and New York City. As is frequently the case when Norfolk picks up 10” or more snow, cities such as Baltimore (Trace); New York (0.4”), Philadelphia (0.1”), and Washington (0.1”) picked up less than 1” of snow. Three Thoughts Going Forward: 1. Saturday night through Sunday will see a significant rainfall in parts of eastern Texas. 1”-3” of rain is likely in Galveston and Houston. 2. The Southwest will see much warmer than normal conditions from Monday through Friday. Phoenix and Tucson could see their highest temperatures so far this year. The temperature could approach or reach record levels on February 26-27 in both Phoenix and Tucson. Phoenix will likely see its first 90° readings this year. 3. No significant (6” or above) snowstorms are likely from Washington, DC to Boston or in the major Great Lakes cities (Chicago, Detroit, Indianapolis, Milwaukee, and Toronto). Longer-Range: There are growing indications that a significant pattern realignment could occur in early March, possibly preceded by a fairly sharp cold shot. Note: With winter coming to an end on February 28, this will be the last regular weekly post in this thread. The post will be verified.

The coldest weather of this month is now moving into the past. It will turn milder late in the weekend. This milder weather will then continue next week. The middle of next week could become quite mild with the mercury reaching 50° or above in New York City. Washington, DC could see highs reach 60° or above. There remain indications that a major pattern re-alignment could take place starting in the first week of March bringing an end to a persistently cold regime that has predominated through most of the winter. The pattern change will likely follow a brief but fairly sharp cold shot. A powerful PNA ridge is currently in place. Historical experience suggests that the presence of such a ridge at this time of year has been followed by the absence of major snowfalls in the New York City area. The PNA reached +1.500 on February 19th and currently stands at +1.776. In all 12 years that saw the PNA reach +1.500 or above on February 15 or later since 1950, the remainder of winter saw no 10" or greater snowstorms. If historic experience holds true yet again, that would make the Winter 2024-2025 the fourth consecutive winter without a 10" or above snowstorm in New York City. The last time that happened was during Winter 2016-2017 through Winter 2019-2020. Most of the 12 winters cited above went on to see some additional measurable snowfall with a few seeing a 6"+ storm. The ENSO Region 1+2 anomaly was +0.9°C and the Region 3.4 anomaly was -0.3°C for the week centered around February 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.03°C and the ENSO Region 3.4 anomaly has averaged -0.65°C. La Niña conditions have peaked and are beginning to fade. La Niña conditions will likely persist into the start of spring. The SOI was -5.24 today. The preliminary Arctic Oscillation (AO) was +0.800 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 95% probability that New York City will have a colder than normal February (1991-2020 normal). February will likely finish with a mean temperature near 33.7° (2.2° below normal).

At present, I believe it's premature to highlight potential for winter storms in New York City in the long-range at this time of year with much degree of accuracy, especially as one big factor suggests otherwise. Additional measurable snow this season still seems reasonably likely. My lack of confidence concerns significant (6"+) or major (10"+) snowstorms in the New York City area. In the heart of winter, from January through the first two weeks of February, nature follows a reasonably clear script. When the Arctic Oscillation turns negative (AO-) and the Pacific-North American pattern trends positive (PNA+), the stage is set for snowfall in the New York City area. The likelihood of significant or major snowstorms is well above climatology during such patterns except when the AO plunges beyond -3.000 in January due to January's long wavelengths. To proactively address common misperceptions of patterns, it is important to know what patterns can and cannot do. In general, patterns provide insight into potential for a broad area e.g., the Middle Atlantic region, 5-7 days in advance. They can alert one to look for the potential of an event. However, patterns cannot provide details for specific locations within the region. Synoptic details determine whether the potential is realized and how specific locations are impacted. Winter 2024-2025 was no exception. During January 1 through February 14, an AO-/PNA+ pattern prevailed on 58% of days. However, those 58% of days accounted for 88% of days with measurable snowfall and 88% of total snowfall during this period, including New York City's biggest snowstorm (3.1"). Those days also saw Washington, DC and Baltimore get blanketed by a 6"+ snowstorm. But as the calendar passes mid-February, the storyline shifts. During the second half of February, the most formidable snow events tend to arise from a different combination: AO-/PNA-. A PNA+ often leads to suppression in the realm of late February's shortening wave lengths when the AO is negative. The recent snowstorm that brought 11.0" to Norfolk was the latest such example. Even worse, when PNA+ ridges grow too strong during the second half of February—pushing to +1.500 or above—they often play the role of a harsh gatekeeper, shutting the door on any chance of a major snowstorm for the rest of the snow season in the New York City area. Winter 2024-2025 will again challenge that "gatekeeper." In the 12 previous cases since 1950, New York City saw no major snowstorms once the PNA reached +1.500 during the February 15-29 period. Time will tell whether Winter 2024-2025 has a different outcome. Then comes March, and the narrative dissolves into uncertainty. There is no longer any dominant pattern. Even as a positive North Atlantic Oscillation (NAO+) has been present during six of New York City’s seven snowstorms of 6 inches or more during March 1-15 since 1950, the sample size is too small to trust the pattern fully. As the calendar advances beyond mid-March, the potential insight offered by large-scale patterns vanishes almost entirely. Now, it’s all about the fleeting, unpredictable nature of shortwaves and the dwindling reservoirs of cold air left to tap. Forecasting at this point becomes a high-stakes waiting game. Chasing shortwaves 5+ days out is like chasing shadows. Models don't become highly skillful with synoptic details until 1-3 days out. Sometimes they struggle within even this period.

All seasonal snowfall is included.