donsutherland1

The storm responsible for the most recent rainfall continues to pull away from the region. Storm total rainfall amounts included: Allentown: 0.56" Boston: 1.03" Bridgeport: 0.72" Islip: 0.82" New York City: 1.16" Newark: 1.23" Philadelphia: 0.23" Providence: 1.33" Tomorrow will be partly sunny and somewhat cooler. However, additional potential for storms exists through at least the next two weeks. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions, even as the forecast AO-/PNA- pattern is typically not a very snowy one. There continues to be ensemble support for a possible snow event in the region during the January 21-23 timeframe. Another timeframe highlighted by the ensembles is January 25-28. The latter period may have greater potential. AO-/PNA- patterns are typically not snowy. The frequency of measurable snowfall is just over 90% of climatology in Boston and Philadelphia and around 80% of climatology in New York City for the January 21-31, 1950-2020 period. The frequency of 2" or more daily snowfall was just above 90% of climatology for Philadelphia, but fell sharply to 50% of climatology in New York City and 65% of climatology in Boston. For daily snowfall amounts in excess of 2", the frequency fell sharply for Philadelphia. As a result, such patterns typically have produced significant snowstorms (6" or above snowfall) in the northern Middle Atlantic and southern New England regions during late January. The biggest snowfalls during an AO-/PNA- pattern during the January 20-31, 1950-2020 period were as follows: Boston: 7.3", January 21, 2011; New York City: 4.2", January 21, 2011; and, Philadelphia: 3.0", January 20, 2000. Neither event is a certainty at this point in time. Afterward, the evolution of the AO will determine whether potential for measurable snow events will continue into February. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.07°C. La Niña conditions will likely prevail at least through the winter. The SOI was +20.26 today. Today, the preliminary Arctic Oscillation (AO) figure was -2.042. On January 15 the MJO was in Phase 4 at an amplitude of 1.140 (RMM). The January 14-adjusted amplitude was 1.222. Following a significant stratospheric warming event, the stratosphere is now cooling. The cooling will likely accelerate during the second half of January. The mean zonal winds have reversed at 1 mb and 10 mb. They have all but died at 30 mb and might still reverse for a brief period. In the wake of this warming event, the polar vortex will split with the dominant piece will, as is typical for vortex-splitting events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. Blocking appears likely to continue into at least the last week of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 80% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.2°.

Both 1997-98 and 2001-02 had only two measurable snow events.

Morning thoughts... Today will be mostly cloudy and still mild. Temperatures will likely reach the upper 40s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 47° Newark: 49° Philadelphia: 48° Somewhat cooler air will arrive for tomorrow and Monday.

Readings across the Middle Atlantic and southern New England regions were much above normal during the first 15 days of January. At New York City, the mean temperature was 37.4° (4.7° above normal). A storm will bring showers and periods of rain tonight into tomorrow. A general 0.50"-1.00" is likely across the region. Parts of Long Island and New England could see 1.00"-1.50" rain. This system could mark the beginning of a more active weather pattern. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions. There has been persistent ensemble support during the January 21-23 timeframe for at least some snowfall in the region. Another timeframe highlighted by the ensembles is January 26-28. The latter period may have greater potential. Nevertheless, neither event is a certainty at this point in time. Afterward, the evolution of the AO will determine whether such potential continues into February. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.07°C. La Niña conditions will likely prevail at least through the winter. The SOI was +22.38 today. Today, the preliminary Arctic Oscillation (AO) figure was -2.824. On January 14 the MJO was in Phase 3 at an amplitude of 1.216 (RMM). The January 13-adjusted amplitude was 1.232. Following a significant stratospheric warming event, the stratosphere is now cooling. The cooling will likely accelerate during the second half of January. The mean zonal winds have reversed at 1 mb and 10 mb. They have all but died at 30 mb and might still reverse for a brief period. In the wake of this warming event, the polar vortex will split with the dominant piece will, as is typical for vortex-splitting events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. Blocking appears likely to continue into at least the last week of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 80% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.3°.

Winter 1912-13 saw just 0.3" snow following 11.4" in December (December 24, 1912). 0.1" fell during January 1-15. That's the benchmark winter for least snowfall following a December that saw 10" or more snow.

Morning thoughts... Today will be mostly cloudy and mild. Showers could arrive late in the day. Temperatures will likely reach the upper 40s in much of the region. A few locations could top out in the lower 50s. Likely high temperatures around the region include: New York City (Central Park): 48° Newark: 50° Philadelphia: 52° A storm will bring showers or periods of rain overnight into tomorrow morning.

A relatively quiet weather pattern remains in place. The dry weather could last through much of this week before a storm impacts the region late Friday or Saturday with some showers or perhaps periods of rain. The first 15 days of January are well on track toward finishing generally warmer than normal across the northeastern United States, Quebec, and much of eastern Canada overall. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions. There has been persistent ensemble support during the January 21-23 timeframe for at least some snowfall in the region. Afterward, the evolution of the AO will determine whether such potential continues into February. Uncertainty about the long-range has increased. There had been emerging ensemble guidance showing that the AO could go positive in the closing week of January, but more recent guidance shows a continuation of Arctic blocking. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.07°C. La Niña conditions will likely prevail at least through the winter. The SOI was +20.26 today. Today, the preliminary Arctic Oscillation (AO) figure was -1.620. On January 13 the MJO was in Phase 3 at an amplitude of 1.232 (RMM). The January 12-adjusted amplitude was 1.259. Following a significant stratospheric warming event, the stratosphere is now cooling. The mean zonal winds have reversed at 1 mb and 10 mb. They could still reverse at 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. Blocking appears likely to continue into at least the last week of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 82% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.5°.

Morning thoughts... Today will be variably cloudy and unseasonably mild. Temperatures will likely reach the upper 40s in much of the region. A few locations could top out in the lower 50s. Likely high temperatures around the region include: New York City (Central Park): 48° Newark: 49° Philadelphia: 50° A storm could bring some rain or showers to the region late Friday or Saturday.

A relatively quiet weather pattern remains in place. The dry weather could last through much of this week before a storm impacts the region late Friday or Saturday. The first 15 days of January are well on track toward finishing generally warmer than normal across the northeastern United States, Quebec, and much of eastern Canada overall. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions. Afterward, the evolution of the AO will determine whether such potential continues into February. Uncertainty about the long-range has increased. There had been emerging ensemble guidance showing that the AO could go positive in the closing week of January, but more recent guidance shows a continuation of Arctic blocking. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.07°C. La Niña conditions will likely prevail at least through the winter. The SOI was +23.79 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.728. On January 12 the MJO was in Phase 3 at an amplitude of 1.259 (RMM). The January 11-adjusted amplitude was 1.242. Following a significant stratospheric warming event, the stratosphere is now cooling. The mean zonal winds have reversed at 1 mb and 10 mb. They could still reverse at 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. Blocking appears likely to continue into at least the last week of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 84% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.7°.

Morning thoughts... Today will be variably cloudy. Temperatures will likely reach the lower and middle 40s in much of the region. Likely high temperatures around the region include: New York City (Central Park): 42° Newark: 45° Philadelphia: 46° The dry weather will continue through much of the week.

A relatively quiet weather pattern remains in place. The dry weather could last through much of this week. A strong flow of Pacific Air will push much milder air eastward. High temperatures could approach or break records in the Northern Plains tomorrow. The temperature could make a run at 50° on either Thursday or Friday in New York City before somewhat cooler air returns. The first 10-15 days of January will likely be generally warmer to perhaps much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada overall. After January 10, the EPS continues to shows a transition during which a trough will move into the East. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions. Afterward, the evolution of the AO will determine whether such potential continues into February. Uncertainty about the long-range has increased. There is emerging ensemble guidance showing that the AO could go positive in the closing week of January. That outcome would likely lead to a warmup near the beginning of February. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.07°C. La Niña conditions will likely prevail at least through the winter. The SOI was +17.39 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.705. On January 11 the MJO was in Phase 3 at an amplitude of 1.243 (RMM). The January 10-adjusted amplitude was 1.384. Following a significant stratospheric warming event, the stratosphere is now cooling. The mean zonal winds have reversed at 1 mb and 10 mb. They could still reverse at 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. Blocking appears likely to continue through at least the first half of January. There is emerging ensemble guidance suggesting that blocking could fade during the last week of January but there remains considerable uncertainty. Based on sensitivity analysis applied to the latest guidance, there is an implied 85% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.7°.

Morning thoughts... Today will be partly cloudy and a bit milder than yesterday. Temperatures will likely reach the lower and middle 40s in much of the region. Likely high temperatures around the region include: New York City (Central Park): 41° Newark: 43° Philadelphia: 44° The dry weather will continue through much of the week.

https://public.tableau.com/profile/don.sutherland#!/vizhome/NYCArea6Snowstorms/Dashboard1

A relatively quiet weather pattern remains in place. The dry weather could last through much of this week. A strong flow of Pacific Air will push much milder air eastward. On Wednesday, high temperatures could approach or break records in the Northern Plains. The temperature could make a run at 50° on either Thursday or Friday in New York City before somewhat cooler air returns. The first 10-15 days of January will likely be generally warmer to perhaps much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada overall. After January 10, the EPS continues to shows a transition during which a trough will move into the East. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions. Afterward, the evolution of the AO will determine whether such potential continues into February. Uncertainty about the long-range has increased. There is emerging ensemble guidance showing that the AO could go positive in the closing week of January. That outcome would likely lead to a warmup near the beginning of February. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -1.1°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.77°C and the ENSO Region 3.4 anomaly has averaged -1.07°C. La Niña conditions will likely prevail at least through the winter. The SOI was +15.17 today. Today, the preliminary Arctic Oscillation (AO) figure was -1.056. On January 10 the MJO was in Phase 3 at an amplitude of 1.343 (RMM). The January 9-adjusted amplitude was 1.444. Following a significant stratospheric warming event, the stratosphere is now cooling. The mean zonal winds have reversed at 1 mb and 10 mb. They could still reverse at 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. Blocking appears likely to continue through at least the first half of January. There is emerging ensemble guidance suggesting that blocking could fade during the last week of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 84% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.7°.

Morning thoughts... Today will be partly to mostly sunny and cool. Temperatures will likely reach the upper 30s and lower 40s in much of the region. Likely high temperatures around the region include: New York City (Central Park): 39° Newark: 40° Philadelphia: 42° The dry weather will continue through mid-week.

A relatively quiet weather pattern remains in place. A seasonably cold but dry weekend lies ahead. The dry weather could last through at least the middle of week. The first 10-15 days of January will likely be generally warmer to perhaps much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada overall. After January 10, the EPS continues to shows a transition during which a trough will move into the East. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions. Afterward, the evolution of the AO will determine whether such potential continues into February. However, uncertainty about the long-range has increased. There is emerging ensemble guidance showing that the AO could go positive in the closing week of January. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.2°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.80°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least through the winter. The SOI was +8.20 today. Today, the preliminary Arctic Oscillation (AO) figure was -2.086. On January 9 the MJO was in Phase 3 at an amplitude of 1.443 (RMM). The January 8-adjusted amplitude was 1.618. Following a significant stratospheric warming event, the stratosphere is now cooling. The mean zonal winds have reversed at 1 mb and 10 mb. They could still reverse at 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. Blocking appears likely to continue through at least the first half of January. There is emerging ensemble guidance suggesting that blocking could fade during the last week of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 84% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.6°.

Morning thoughts... Today will be partly to mostly sunny and cool. Temperatures will likely reach the lower 40s in much of the region. Likely high temperatures around the region include: New York City (Central Park): 42° Newark: 43° Philadelphia: 44° The dry weather will continue through mid-week.

A relatively quiet weather pattern remains in place. A seasonably cold but dry weekend lies ahead. The dry weather could last through at least the middle of week. The first 10-15 days of January will likely be generally warmer to perhaps much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada overall. After January 10, the EPS continues to shows a transition during which a trough will move into the East. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions. Afterward, the evolution of the AO will determine whether such potential continues into February. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.2°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.80°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least through the winter. The SOI was +4.25 today. Today, the preliminary Arctic Oscillation (AO) figure was -2.867. On January 8 the MJO was in Phase 3 at an amplitude of 1.617 (RMM). The January 7-adjusted amplitude was 1.595. Following a significant stratospheric warming event, the stratosphere is now cooling. The mean zonal winds have reversed at 1 mb and 10 mb. They could reverse at 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue through at least the first half of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 80% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.3°.

A complex pattern evolution is underway. The SSW coupled with a reinvigorated moderate La Niña is a challenging environment where model skill scores are likely to be lower than typical. The weeklies beyond two weeks have little or no skill relative to climatology.

Gradient patterns can produce. But I don’t like this pattern currently shown at the end of the EPS for a number of reasons: 1. Gradient patterns that produce a lot of snow typically have a trough all across Canada 2. There is a lot of cold not marginal air available to be tapped in eastern Canada The February 1994 500 mb pattern provides a classic example of the kind of gradient patterns that work. The forecast one does not resemble that pattern.The North American trough is north-south oriented, not east-west oriented across Canada. The ridge in the southeast is more expansive and stronger. If the pattern does, in fact, evolve toward that, I don’t believe we’ll see much snow until it changes again. Earlier runs of the EPS were better. Let’s see what the 12z cycle shows.

That’s an important point about the sudden stratospheric warming event (SSW). With the polar vortex splitting, Eurasia was favored for the severe cold. That’s, by far, the most common case, as displacement events favor North America. The Twitter accounts reflexively proclaiming that the stratospheric warming meant that severe cold would pour into the region have little understanding of such events and their implications. That’s the fact. One sees their track record with stratospheric warmings over and over again, including forecasts for such events that never develop, because they focus solely on one specific layer of the stratosphere (either 30 mb or 10 mb) not all layers. There was potential for a snowy but not overly cold pattern here, but favorable 500 mb patterns don’t amount to much without surface features. That’s why potential isn’t always realized. We’ll have to see if this is the case again during the second half of January where there will be potential (somewhat favorable to favorable upper air pattern). I’m not ready to write things off for the second half of January just yet. But when the AO goes positive and/or the PNA goes negative, then the window of opportunity will close. For January, the AO-/PNA+ pattern is the most favorable for significant (6” or above) snowstorms for the Philadelphia and New York City areas.

Morning thoughts... Today will be partly to mostly sunny and cool. Temperatures will likely reach the middle and upper 30s in much of the region. Likely high temperatures around the region include: New York City (Central Park): 36° Newark: 38° Philadelphia: 38° The dry weather will continue through the weekend.

A relatively quiet weather pattern remains in place. A seasonably cold but dry weekend lies ahead. The dry weather could last into early next week. The first 10-15 days of January will likely be generally warmer to perhaps much warmer than normal across the northeastern United States, Quebec, and much of eastern Canada overall. After January 10, the EPS continues to shows a transition during which a trough will move into the East. During the second half of January, there will be some potential for snow events in the Middle Atlantic and southern New England regions. Afterward, the evolution of the AO will determine whether such potential continues into February. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was -1.2°C for the week centered around December 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.80°C and the ENSO Region 3.4 anomaly has averaged -1.10°C. La Niña conditions will likely prevail at least through the winter. The SOI was +16.77 today. Today, the preliminary Arctic Oscillation (AO) figure was -2.893. On January 7 the MJO was in Phase 3 at an amplitude of 1.595 (RMM). The January 6-adjusted amplitude was 1.289. Following a significant stratospheric warming event, the stratosphere is now cooling. The mean zonal winds have reversed at 1 mb and 10 mb. They could reverse at 30 mb. In the wake of this warming event, the polar vortex will likely split. The dominant piece will, as is typical with such events, migrate to Eurasia. The significant December 16-17 snowstorm during what has been a blocky December suggests that seasonal snowfall prospects have increased especially from north of Philadelphia into southern New England. At New York City, there is a high probability based on historic cases that an additional 20" or more snow will accumulate after December. Were blocking to disappear, snowfall prospects would diminish. For now, blocking appears likely to continue through at least the first half of January. Based on sensitivity analysis applied to the latest guidance, there is an implied 78% probability that New York City will have a warmer than normal January. January will likely finish with a mean temperature near 35.0°.

This is correct. The idea that the La Niña would collapse was incorrect. It should persist through the winter and that base case has not changed. There can be fluctuations in the anomalies and a temporary warming may have driven speculation that it was rapidly dissipating. Over the past two weeks, the temporary warming reversed (something the CFSv2 showed).

At some point, I may create one for ABE. That will require some research. However, the chart is as wide as Tableau Public permits. When I added ISP, the chart reached the edge of the permissible boundaries of the software.