donsutherland1

That was a truly amazing period that unfolded. It was the Middle Atlantic Region’s version of New England’s “Great Snow.”

Morning thoughts... Today will see a continuation of the recent fair weather. It will be a little cooler than yesterday was. Temperatures will likely top out mainly in the middle and upper 40s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 46° Newark: 47° Philadelphia: 50° A dry but cool weekend lies ahead. Next week could see the arrival of the warmest weather so far this season.

Under brilliant sunshine, temperatures soared into the 50s across most of the region today. Tomorrow will be fair but cooler. Overall, the first week of March will see variable temperatures, even as the week will very likely average cooler than normal. Another short but sharp cold shot is possible Friday through the weekend. Afterward, a strong warming trend should commence. Parts of the region will likely see their warmest temperatures so far during the second week of March. The 60° isotherm could extend into southern and perhaps even central New England during the height of the warmth. Central Park will very likely see its first 60° reading since December 25 and perhaps its highest temperatures since late November. Statistical guidance based on the state of the ENSO and forecast teleconnections implies that the first half of March could wind up generally 1°-3° above normal in the Middle Atlantic and southern New England regions. The latest dynamical guidance is suggests temperature anomalies toward or just below the bottom of that range for the first half of March. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -1.2°C for the week centered around February 24. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.60°C and the ENSO Region 3.4 anomaly has averaged -0.80°C. La Niña conditions will likely prevail at least through most of March. The SOI was -6.08 today. The SOI has now been negative for four consecutive days. The last time that occurred was October 25-29, 2020 when the SOI was negative for five consecutive days. This development could be an early indication that what has been a fairly stable La Niña regime throughout the winter could be moving closer to its end stages. The preliminary Arctic Oscillation (AO) figure was -0.300 today. On March 2 the MJO was in Phase 7 at an amplitude of 1.046 (RMM). The March 1-adjusted amplitude was 1.007 (RMM). 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. Since January 1, New York City has picked up 28.1" snow. Winters that saw December receive 10" or more snow, less than 10" in January, and then 10" or more in February in New York City, saw measurable snowfall in March or April in 83% of cases. Winter 2009-2010 was the exception where only a trace of snow was recorded. This group of winters saw 6" or more snow during the March-April period in 50% of the cases. All said, it is more likely than not that there will be measurable snowfall after February.

Thanks. Do you have a link to the site. My bookmark goes back to an NCDC.NOAA.gov page that has been replaced by the one you referenced.

Snowfall amounts for the April 1956 storm included: Boston: 3.1”; Brooklyn (New York Avenue): 3.0”; Hartford: 4.3”; Hempstead-Garden City, NY: 4.0”; Mineola, NY: 4.0”; New York City: 4.2”; Newark: 3.4”; Providence: 1.2”; and, Scarsdale, NY: 5.0” No data is available from JFK. The trace shown for LGA is suspect.

Morning thoughts... In contrast to yesterday, temperatures were in the 20s and 30s this morning rather than teens and 20s. Today will be partly sunny and much milder. Temperatures will likely top out mainly in the upper 40s and lower 50s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 48° Newark: 50° Philadelphia: 54° Tomorrow will be fair but cooler. Early next week could see the arrival of the warmest weather so far this season.

After a day characterized by unseasonably cold temperatures and wind chills more typical of mid-winter than early March, milder air will return for a short time. Under mainly sunny skies, temperatures will likely reach the upper 40s with some lower 50s in the northern Mid-Atlantic and southern New England areas tomorrow. Overall, the first week of March will see variable temperatures, even as the week will very likely average cooler than normal. Another short but sharp cold shot is possible Friday through the weekend. Afterward, a strong warming trend should commence. Parts of the region will likely see their warmest temperatures so far during the second week of March. The 60° isotherm could extend into southern and perhaps even central New England during the height of the warmth. Central Park will very likely see its first 60° reading since December 25 and perhaps its highest temperatures since late November. Statistical guidance based on the state of the ENSO and forecast teleconnections implies that the first half of March could wind up generally 1°-3° above normal in the Middle Atlantic and southern New England regions. The latest dynamical guidance is suggests temperature anomalies toward the bottom of that range for the first half of March. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -1.2°C for the week centered around February 24. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.60°C and the ENSO Region 3.4 anomaly has averaged -0.80°C. La Niña conditions will likely prevail at least through most of March. The SOI was -6.80 today. The SOI has now been negative for three consecutive days. The last time that occurred was October 25-29, 2020 when the SOI was negative for five consecutive days. This development could be an early indication that what has been a fairly stable La Niña regime throughout the winter could be moving closer to its end stages. The preliminary Arctic Oscillation (AO) figure was +0.775 today. On March 1 the MJO was in Phase 6 at an amplitude of 1.004 (RMM). The February 28-adjusted amplitude was 0.887 (RMM). 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. Since January 1, New York City has picked up 28.1" snow. Winters that saw December receive 10" or more snow, less than 10" in January, and then 10" or more in February in New York City, saw measurable snowfall in March or April in 83% of cases. Winter 2009-2010 was the exception where only a trace of snow was recorded. This group of winters saw 6" or more snow during the March-April period in 50% of the cases. All said, it is more likely than not that there will be measurable snowfall after February.

IMO, we should move on. The guidance suggests little has changed. The storm will be suppressed.

The Arctic Oscillation (AO) is forecast to rise sharply over the next 7-10 days. It will very likely peak at or above +3.000 and several ensemble members suggest that it could top out at +4.000 or above. This outcome will help bring the warmest air so far this season into the Middle Atlantic and southern New England areas. Temperatures will likely reach the 60s in New York City during the height of the warmth. Philadelphia could see the temperature approach or even reach 70° if some of the guidance is correct. This does not mean that New York City or Philadelphia have seen their last snowfall. Since 1950, there have been three cases where the AO peaked at +4.000 or above during the first half of March. All of those cases subsequently saw additional measurable snow in both cities. 1956: Maximum AO: +4.692, March 2 March 12-24: 21.1" snow in New York City (snowiest March 12-24 period on record) March 12-24: 10.9" snow in Philadelphia (3rd snowiest March 12-24 period on record) April 8: A storm brought measurable snow to New York City Note: The snowy March period coincided with a return of AO blocking, which persisted through late April. 1990: Maximum AO: +4.638, March 6 April 7: New York City: 0.6" snow; Philadelphia: 2.4” snow Note: The AO never went negative again through April 7. The April 7 snowfall was largely a function of shortening wave lengths. 2015: Maximum AO: +5.588, March 8 March 20-21: A storm brought measurable snow to such cities as Baltimore, Boston, New York City, Newark, and Philadelphia. New York City picked up 4.5” snow and Philadelphia received 3.9” snow. Note: The snowstorm was preceded by a brief period of AO blocking. The sample size is very small, so the only conclusion that is useful is that one should not write off the possibility of snowfall following the AO’s forecast peak. Were the AO’s peak to occur near or after March 15, the prospect for additional measurable snowfall would be low. All four cases that saw the AO peak on or after March 15 saw no measurable snowfall following the AO’s peak. Those cases were 1968, 1978, 1986, and 2020.

Morning thoughts... Overnight, high winds brought cold air into the region. Low temperatures this morning included: Albany: 9°; Allentown: 20°; Boston: 13°; Bridgeport: 20°; Islip: 21°; New Haven: 21°; New York City: 21°; Newark: 21°; Philadelphia: 25°; Poughkeepsie: 18°; and, White Plains: 18° Today will be mostly sunny, windy, and unseasonably cold. Temperatures will likely top out mainly in the middle 30s in most of the region. With the gusty wind, it will feel more like mid-winter. Likely high temperatures around the region include: New York City (Central Park): 36° Newark: 37° Philadelphia: 37° Tomorrow will be fair and noticeably milder. Early next week could see the arrival of the warmest weather so far this season.

A cold air mass is overspreading the region. Tomorrow will be fair but unseasonably cold. Moderation will quickly follow. Overall, the first week of March will see variable temperatures, even as the week will very likely average cooler than normal. Another short but sharp cold shot is possible toward the end of the first week of March. Afterward, the ensembles are in good agreement that there will be a warming trend. The 3/1 12z EPS forecasts 500 mb height anomalies that are reasonably similar to those that prevailed during March 9-15, 2020 at 216 hours. That period saw much above normal temperatures in the Middle Atlantic and New England areas. Therefore, the potential exists that parts of the region could see their warmest temperatures so far during the second week of March. Statistical guidance based on the state of the ENSO and forecast teleconnections implies that the first half of March could wind up generally 1°-3° above normal in the Middle Atlantic and southern New England regions. The latest dynamical guidance is suggests temperature anomalies toward the bottom of that range for the first half of March. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -1.2°C for the week centered around February 24. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.60°C and the ENSO Region 3.4 anomaly has averaged -0.80°C. La Niña conditions will likely prevail at least through most of March. The SOI was -8.47 today. The preliminary Arctic Oscillation (AO) figure was +1.356 today. On February 28 the MJO was in Phase 6 at an amplitude of 0.886 (RMM). The February 27-adjusted amplitude was 0.990. 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. Since January 1, New York City has picked up 28.1" snow. Winters that saw December receive 10" or more snow, less than 10" in January, and then 10" or more in February in New York City, saw measurable snowfall in March or April in 83% of cases. Winter 2009-2010 was the exception where only a trace of snow was recorded. This group of winters saw 6" or more snow during the March-April period in 50% of the cases. All said, it is more likely than not that there will be measurable snowfall after February.

Best guess: second half of March, but no guarantees.

At this point, even as it is a week away, I believe there is only a low probability of an impactful snowfall (4" or more) in the general New York City area (NYC-JFK-LGA-EWR and suburbs). First, there has been very little support among the ensemble members for such an event. Run-to-run continuity has been good. One would typically see a clustering of ensemble members. That there was a seemingly errant prior GFSv16 run does not give much confidence. The global models are also in good and continuing agreement right now. Second, the AO is forecast to rise sharply (probably between +2.000 and +3.000) during this event. Interestingly enough, all 6 cases where storms brought 4" or more snow to NYC in the 3/1-15/1950-2020 period with an AO of +2.000 or above have occurred since 2009. However, the forecast 500 mb pattern resembles none of those cases. Third, there is some uncertainty concerning the timing of any phasing/partial phasing. However, if there were meaningful potential of favorable timing, one should start seeing it on individual ensemble members. Support on such members has been very limited (first point). The timeframe involved is really the only significant factor arguing for possible changes. But all things considered above, a suppressed solution seems to be the most likely outcome.

Morning thoughts... Any rain will depart this morning. The clouds will gradually give way to increasing sunshine. It will become increasingly windy. Temperatures will likely reach the upper 40s and lower 50s across much of the region before falling sharply later in the day. Likely high temperatures include: New York City (Central Park): 49° Newark: 51° Philadelphia: 53° Tomorrow will be partly sunny, blustery and cold. 30-Day Verification: New York City (Central Park): Average daily forecast: 37.1° Average temperature: 38.0° Average error: 1.9° Newark: Average daily forecast: 37.6° Average temperature: 37.8° Average error: 2.0° Philadelphia: Average daily forecast: 38.9° Average temperature: 39.1° Average error: 1.6°

February 2021 finished with a mean temperature of 34.0°, which was 1.3° below normal. Tomorrow will see any rain come to an end with partial clearing. It will become increasingly windy. Temperatures could surge into the upper 40s and lower 50s before falling sharply. The first week of March will see variable temperatures, even as the week will very likely average cooler than normal. A short but sharp cold shot is possible both early in that week and toward the end of the first week of March. Afterward, the ensembles are in good agreement that there will be a warming trend. The 2/28 12z EPS forecasts 500 mb height anomalies that are reasonably similar to those that prevailed during March 9-15, 2020 at 240 hours. That period saw much above normal temperatures in the Middle Atlantic and New England areas. Therefore, the potential exists that parts of the region could see their warmest temperatures so far during the second week of March. Overall, it appears that March will wind up at least somewhat warmer than normal. Statistical guidance based on the state of the ENSO and forecast teleconnections implies that the first half of March could wind up generally 1°-3° above normal in the Middle Atlantic and southern New England regions. The latest dynamical guidance is suggests temperature anomalies toward the bottom of that range for the first half of March. The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -0.7°C for the week centered around February 17. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.47°C and the ENSO Region 3.4 anomaly has averaged -0.93°C. La Niña conditions will likely prevail at least through mid-March. The SOI was -5.43 today. The preliminary Arctic Oscillation (AO) figure was +2.408 today. For winter 2020-21, the preliminary AO average was -1.758. The AO was negative on 83% of days, at or below -1.000 on 74% of days, and at or below -2.000 on 54% of days. The lowest figure was -5.314 on February 11. The highest figure was +2.980 on February 26. On February 27 the MJO was in Phase 6 at an amplitude of 0.994 (RMM). The February 26-adjusted amplitude was 1.048. 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. Since January 1, New York City has picked up 28.1" snow. Winters that saw December receive 10" or more snow, less than 10" in January, and then 10" or more in February in New York City, saw measurable snowfall in March or April in 83% of cases. Winter 2009-2010 was the exception where only a trace of snow was recorded. This group of winters saw 6" or more snow during the March-April period in 50% of the cases. All said, it is more likely than not that there will be measurable snowfall after February.

Some sleet is falling in Larchmont and Mamaroneck, NY.

DCA _ NYC _ BOS __ ORD _ ATL _ IAH ____ DEN _ PHX _ SEA 1.5 1.4 1.2 3.0 2.5 3.1 2.2 0.3 -2.1

Morning thoughts... Rain will arrive today. It will also be cooler than yesterday. Temperatures will likely top out mainly in the middle and upper 40s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 45° Newark: 45° Philadelphia: 47° Rain will end tomorrow and it will be milder for a time. However, a brief shot of colder air will pour into the region later in the day.

Another round of rain will move into the region tomorrow. Temperatures will run 5°-10° cooler than today's highs. The first week of March will see variable temperatures, even as the week averages cooler than normal. A short but sharp cold shot is possible near the end of the first week of March. Afterward, the ensembles are in good agreement that there will be a warming trend. Statistical guidance based on the state of the ENSO and forecast teleconnections implies that the first half of March could wind up generally 1°-3° above normal in the Middle Atlantic and southern New England regions. The latest dynamical guidance is suggests temperature anomalies toward the bottom of that range for the first half of March. During the 1991-2020 base period, the March 1-10 temperature has averaged 39.7° in New York City and 40.9° in Philadelphia. Measurable snow fell on 10% of days for both cities. During cases when the AO was +1.000 or above and the PNA was negative, the state of the SOI often made the difference between a colder/snowier or warmer/less snowy outcome. When the SOI was negative, the mean temperature in New York City was 39.5° and it was 39.6° in Philadelphia. Measurable snow fell on 20% of days in New York City and 17% of days in Philadelphia (well above the climatological frequency). When the SOI was positive, the mean temperature in New York City was 41.6° and it was 42.3° in Philadelphia. In such cases, measurable snow was observed on 13% of days in both cities. In sum, if this data holds up, even as a milder regime settles in, there could be some chance of a measurable snow event during the first 10 days of March in the northern Middle Atlantic region. Interior sections would likely be favored for measurable snow, as would central and upstate New York and New England. The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -0.7°C for the week centered around February 17. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.47°C and the ENSO Region 3.4 anomaly has averaged -0.93°C. La Niña conditions will likely prevail at least through mid-March. The SOI was +1.44 today. The preliminary Arctic Oscillation (AO) figure was +2.496 today. On February 26 the MJO was in Phase 5 at an amplitude of 1.046 (RMM). The February 25-adjusted amplitude was 1.184. Over the past five days, the MJO has moved from Phase 7 to Phase 5. Based on the latest guidance, no significant stratospheric warming event is likely through the first week of March. This will be the last notice about the state of the stratosphere until next winter, as the typical seasonal warming lies ahead in March. 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. Since January 1, New York City has picked up 28.1" snow. Winters that saw December receive 10" or more snow, less than 10" in January, and then 10" or more in February in New York City, saw measurable snowfall in March or April in 83% of cases. Winter 2009-2010 was the exception where only a trace of snow was recorded. This group of winters saw 6" or more snow during the March-April period in 50% of the cases. All said, it is more likely than not that there will be measurable snowfall after February. Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a colder than normal February. February will likely finish with a mean temperature near 33.9° (1.4° below normal).

Rapidly disappearing snow cover:

Morning thoughts... Today will be mostly cloudy with periods of rain. It will turn milder. Temperatures will likely top out mainly in the upper 40s and lower 50s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 51° Newark: 52° Philadelphia: 54° After a partly cloudy night, clouds will increase and another bout of rain will arrive tomorrow.

A weak system will bring light precipitation to the region late tonight into tomorrow. There could be some snow with a minor accumulation north and west of New York City. It will also turn milder during tomorrow afternoon. Overall, temperatures will likely remain generally above normal in the Middle Atlantic and southern New England areas into the first week of March. Some of the guidance has moved toward a cooler opening to March largely on account of a short but sharp cold shot late in the first week of the month. Afterward, the ensembles are in good agreement that there will be a warming trend. Statistical guidance based on the state of the ENSO and forecast teleconnections implies that the first half of March could wind up generally 1°-3° above normal in the Middle Atlantic and southern New England regions. The latest dynamical guidance is suggests temperature anomalies toward the bottom of that range for the first half of March. During the 1991-2020 base period, the March 1-10 temperature has averaged 39.7° in New York City and 40.9° in Philadelphia. Measurable snow fell on 10% of days for both cities. During cases when the AO was +1.000 or above and the PNA was negative, the state of the SOI often made the difference between a colder/snowier or warmer/less snowy outcome. When the SOI was negative, the mean temperature in New York City was 39.5° and it was 39.6° in Philadelphia. Measurable snow fell on 20% of days in New York City and 17% of days in Philadelphia (well above the climatological frequency). When the SOI was positive, the mean temperature in New York City was 41.6° and it was 42.3° in Philadelphia. In such cases, measurable snow was observed on 13% of days in both cities. In sum, if this data holds up, even as a milder regime settles in, there could be some chance of a measurable snow event during the first 10 days of March in the northern Middle Atlantic region. Interior sections would likely be favored for measurable snow, as would central and upstate New York and New England. The ENSO Region 1+2 anomaly was -0.5°C and the Region 3.4 anomaly was -0.7°C for the week centered around February 17. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.47°C and the ENSO Region 3.4 anomaly has averaged -0.93°C. La Niña conditions will likely prevail at least through mid-March. The SOI was -9.56 today. The preliminary Arctic Oscillation (AO) figure was +2.980 today. That is the highest AO value since November 21, 2020 when the AO was +3.081. On February 25 the MJO was in Phase 6 at an amplitude of 1.184 (RMM). The February 24-adjusted amplitude was 1.117. Based on the latest guidance, no significant stratospheric warming event is likely through the first week of March. 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. Since January 1, New York City has picked up 28.1" snow. Winters that saw December receive 10" or more snow, less than 10" in January, and then 10" or more in February in New York City, saw measurable snowfall in March or April in 83% of cases. Winter 2009-2010 was the exception where only a trace of snow was recorded. This group of winters saw 6" or more snow during the March-April period in 50% of the cases. All said, it is more likely than not that there will be measurable snowfall after February. Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a colder than normal February. February will likely finish with a mean temperature near 33.8° (1.5° below normal).

There was widespread record February warmth in parts of Europe in recent days.

Both February 2014 and February 2015 had snow cover of 1” or more on every day.

Morning thoughts... Today will be partly to mostly sunny and cooler. Temperatures will likely top out mainly in the middle 40s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 46° Newark: 46° Philadelphia: 48° Periods of light rain are likely tomorrow. Precipitation totals will generally come to 0.25”-0.50”. A little frozen precipitation is possible at the start far north and west of New York City. Upstate New York and northern New England will likely see an all snow event. It will also turn milder.