donsutherland1

Detroit Likely Sets a New November Daily Snowfall Record... Through 4 pm, Detroit had picked up 6.0" snow, which broke the November 11 record of 4.1", which was set in 1984. Snow had continued to fall since then. Even as numerous locations have reported updated amounts, no updates have been provided by DTW. However, based on an estimate of precipitation and ratios, it is very likely that the figure has reached 8.0" (7.5"-8.5" estimate). That would set a new daily snowfall record for November. The daily record for November is 7.2", which was set on November 16, 1932. The biggest two-day snowfall total in November is 9.0", which occurred on November 15-16, 1932. Other daily snowfall records for November 11 included: Chicago: 3.4" (old record: 1.9", 1995) Indianapolis: 2.3" (old record: 1.2", 1995) Milwaukee: 3.4" (old record: 2.3", 1995) St. Louis: 1.3" (old record: 1.0", 1911) Finally, at 10 pm CST, Chicago reported a 15° temperature. That tied the daily record low temperature set back in 1950. St. Louis had a temperature of 19°, which was just above the record of 18° set in 1911 and tied in 1950 and 1976. Milwaukee reported a temperature of 16°, which was just above the daily record of 15° set in 1986. 　

From Phys.org: A new study by researchers at the Niels Bohr Institute, University of Copenhagen, Aslak Grinsted, Peter Ditlevsen and Jens Hesselbjerg shows that hurricanes have become more destructive since 1900, and the worst of them are more than three times as frequent now than 100 years ago. A new way of calculating the destruction, compensating for the societal change in wealth, unequivocally shows a climatic increase in the frequency of the most destructive hurricanes that routinely raise havoc on the North American southern and east coasts. The study is now published in PNAS... In previous studies, it proved difficult to isolate the climate signal. The climate signal should be understood as the effect climate change has on hurricane size, strength and destructive force. It was hidden behind variations due to the uneven concentration of wealth, and it was statistically uncertain whether there was any tendency in the destruction. But with the new method, this doubt has been cleared. The weather has, indeed, become more dangerous on the south and east coasts of the U.S. Furthermore, the result obtained by the research team is more congruent with the climate models used to predict and understand the development in extreme weather. It fits with the physics, quite simply, that global warming has the effect that there is an increase in the force released in the most extreme hurricanes. https://phys.org/news/2019-11-hurricanes-bigger-destructive.html The paper can be found here: https://www.pnas.org/content/early/2019/11/05/1912277116

Historic fire weather conditions in Australia:

As of 4 pm local time, Chicago had picked up 3.4" snow, which broke the November 11 record of 1.9" from 1995. Detroit had received 6.0" snow, which broke the daily record of 4.1", which was set in 1984. Only four prior storms saw 6.0" or more daily snowfall in Detroit in November. The unseasonably cold air mass responsible for the daily record snowfall in Chicago and Detroit will push into the region tomorrow accompanied by rain showers that could end as a brief period of wet snow or flurries even in the New York City and Newark areas. However, the probability that New York City would receive measurable snow is low. In fact, all 6 prior cases of 1.0" or more snow in Detroit on November 11 saw no measurable snow in New York City on November 11 or November 12. Thus, the historical data and guidance are well-aligned. Following the frontal passage, numerous cities in the Middle Atlantic and southern New England areas could challenge or set daily record low temperatures on Wednesday morning. Select records for November 13 are: Allentown: 18°, 1996 Baltimore: 22°, 1911 Boston: 14°, 1883 Bridgeport: 23°, 1986 Harrisburg: 21°, 1911 Islip: 24°, 2001 New York City-JFK: 25°, 1986 New York City-LGA: 26°, 1986 New York City-NYC: 24°, 1986 Newark: 24°, 1986 Philadelphia: 24°, 1996 Poughkeepsie: 16°, 2013 Scranton: 19°, 1986 White Plains: 23°, 1986 Washington, DC: 22°, 1911 Another push of cold air is likely for the coming weekend. However, that air mass won't be as cold as the approaching one. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was +0.5°C for the week centered around November 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.68°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20. The SOI was -9.61 today. An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -0.668. Some of the more recent guidance shows the AO remaining strongly negative through the next two weeks. Such an outcome would increase prospects for at least some additional bouts of cold in the East after mid-month. On November 10, the MJO was in Phase 6 at an amplitude of 2.453 (RMM). The November 9-adjusted amplitude was 2.570. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Even as the second half of November will likely experience a pattern change to generally warmer than normal conditions within a few days of November 20, the magnitude of the cold during the first half of the month has made it very likely that November will finish with a cold anomaly in the region. It is likely that November 2019 will be somewhat warmer than November 2018 when the monthly mean temperature was 44.4°. In addition, the MJO has now spent three days in Phase 6 at an amplitude of 1.500 or above. That development reinforces the idea from the strongly negative SOI earlier this month that December will be likely be warmer than normal. Since 1974, five years saw the MJO in Phase 6 at an amplitude of 1.500 or higher for two or more days during the 1974-2018 period: 1985, 1987, 1996, 1998, and 2018. Only 1985 with a mean temperature of 34.2° was colder than normal during December. The mean temperature for those five cases was 39.7°. The 1981-2010 normal monthly temperature for New York City is 37.5°. Based on sensitivity analysis applied to the latest guidance, New York City has an implied 76% probability of experiencing a colder than normal November.

Yes, that’s true.

Detroit reported 6.0" snow. That exceeded the previous daily record of 4.1", which was set in 1984.

A belated congratulations, Uncle W.

Back on October 30, I noted a Social Media forecast suggesting that the kind of severe cold expected later this week would 'lock into place.' At the time, I noted that the idea of such severe cold locking into place was not supported by the forecast teleconnections or latest very long-range guidance. The posted map for the conditions suggested to lock in showed mean temperatures of 8° or more below normal in Chicago and New York City. My conclusion was as follows: ...the coldest weather of the season so far is likely to develop beginning in early November with perhaps the strongest shot of cold reaching the East during the second week of the month. However, even allowing for uncertainty, there is little support for the idea that the notable cold shown at the end of the GEFS will lock in. Considering pattern persistence, the warming might be somewhat slower than modeled, but definitive language about severe cold locking in does not fairly represent things. After the first 10 days, here's what the model guidance shows for the November 16-30 mean temperatures: Chicago: 36.5° (1.2° below normal) New York City: 46.8° (0.9° above normal) In short, the guidance is now showing nothing approximating the severe cold that was supposed to lock into place. Note: Depending which model is used, the numbers may fluctuate. Beyond the forecast horizon of each guidance, normal readings were assumed for the calculations. Additional updates and a final verification will be provided. The main takeway remains: One should not forecast long periods of extremes without strong support for such an outcome.

One of the NAM runs showed a larger impact than the other guidance. One doesn't see such large near-term errors very often anymore.

I have some colleagues at work who didn't get home until after midnight.

Last year, was sort of a special case. One was dealing with a rare near-term forecasting failure. On account of the high impact of that failure, the effects of that outcome will likely continue to guide decision making for some time to come. During the morning of November 15, moderate snow dumped more than the anticipated amounts in both Baltimore and Washington, DC where 1.7" and 1.4" snow fell respectively. Neither city had expected more than a coating of snow. By late morning, heavy snow was moving into the Philadelphia region: By 1 pm, Philadelphia had experienced 1/4-mile visibility and 2" of snow had fallen. At that point, based on an absence of news reports noting significant pre-positioning of equipment and pre-treatment of roads prior to the onset of the heavy snow in the New York City area during the afternoon, either the NYC Sanitation's forecasters were largely oblivious to what was going on south of the City or the NYC Department of Sanitation was taking things too lightly. More than likely, one was dealing with a combination of those two scenarios: low forecaster and Department awareness of real-time events. The New York Times would report a situation that implied that New York City's leadership had been governed by the early forecasts. The newspaper reported, "Leaders in New York and New Jersey came under heavy criticism, but insisted that they had been caught off guard by the ferocity of the storm after early forecasts predicted just a dusting." https://www.nytimes.com/2018/11/16/nyregion/snowstorm-total-delays-commute.html Largely unaware of how things were evolving, the City was caught unprepared for what proved to be a moderate snowstorm (though record-breaking for the date). Around 2 pm, heavy snow pushed into midtown Manhattan. Streets were then rapidly covered by the heavy snow. By the time the storm ended, New York City had picked up a November 15 daily record 6.4" snowfall. In the post-mortem, the City's political leaders shifted significant blame onto commuters for clogging the streets. That happened after the heavy snow was underway. None of that takes away the reality that the City still had several hours to react to a situation that would wind up much worse than the early forecasts had its forecasters and decision makers observed what had happened in Baltimore and Washington and what was underway in Philadelphia.

On Friday, the San Francisco Federal Reserve hosted a conference on climate change. Excerpts from San Francisco Federal Reserve President Mary C. Daly's address are below: Why is the San Francisco Fed hosting a climate conference? ...The answer is simple. It’s essential to achieving our mission... Extreme weather events like hurricanes, floods, and wildfires destroy property and disrupt essential services like health care and education. But they also impact how people buy things. Without power, electronic payment methods – debit cards, credit cards, and mobile services like Apple Pay – don’t work. So you need cash for everything... The Fed’s second core function is the regulation and supervision of the banking system. And climate events are becoming an increasing area of risk for many of the financial firms we supervise. Higher sea levels, heavier rainfalls, dryer conditions, and the associated fallout can cause catastrophic losses to property and casualty insurers – especially if the majority of their clients are geographically concentrated in the affected region. In 2018 alone, it’s estimated that damages from severe weather in the United States cost insurers upwards of $50 billion... Finally, climate change can also influence our third function: conducting monetary policy to achieve our congressionally-mandated goals of full employment and price stability. Early research suggests that increased warming has already started to reduce average output growth in the United States. And future growth may be curtailed even further as temperatures rise. Several of the papers on the program today outline other ways in which the micro- and macro-economic environments may be impacted by climate change. While more work needs to be done to clearly understand these effects, there’s little doubt that we need to recognize, examine, and prepare for these risks in order to fulfill our core responsibilities. https://www.frbsf.org/our-district/files/Speech-Daly-Economics-of-Climate-Change-Conference.pdf

Tomorrow will feature a very mild day for November. However, much colder air is on the way. An unseasonably cold air mass will push into the region on Tuesday. Numerous cities in the Middle Atlantic and southern New England areas could challenge or set daily record low temperatures on Wednesday. Select records for November 13 are: Allentown: 18°, 1996 Baltimore: 22°, 1911 Boston: 14°, 1883 Bridgeport: 23°, 1986 Harrisburg: 21°, 1911 Islip: 24°, 2001 New York City-JFK: 25°, 1986 New York City-LGA: 26°, 1986 New York City-NYC: 24°, 1986 Newark: 24°, 1986 Philadelphia: 24°, 1996 Poughkeepsie: 16°, 2013 Scranton: 19°, 1986 White Plains: 23°, 1986 Washington, DC: 22°, 1911 The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was +0.7°C for the week centered around October 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.67°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20. The SOI was -14.64 today. An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -1.176. Some of the more recent guidance shows the AO remaining strongly negative through the next two weeks. Such an outcome would increase prospects for at least some additional bouts of cold in the East after mid-month. On November 9, the MJO was in Phase 6 at an amplitude of 2.566 (RMM). The November 8-adjusted amplitude was 2.534. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Even as the second half of November will likely experience a pattern change to generally warmer than normal conditions within a few days of November 20, the magnitude of the cold during the first half of the month has made it very likely that November will finish with a cold anomaly in the region. In addition, the MJO has now spent two days in Phase 6 at an amplitude of 1.500 or above. That development reinforces the the idea from the strongly negative SOI earlier this month that December will be likely be warmer than normal. Since 1974, five years saw the MJO in Phase 6 at an amplitude of 1.500 or higher for two or more days during the 1974-2018 period: 1985, 1987, 1996, 1998, and 2018. Only 1985 with a mean temperature of 34.2° was colder than normal during December. The mean temperature for those five cases was 39.7°. The 1981-2010 normal monthly temperature for New York City is 37.5°. Based on sensitivity analysis applied to the latest guidance, New York City has an implied 78% probability of experiencing a colder than normal November.

Yes. Those trees seem very sensitive to the cold. Below is a photo I took of the tree I mentioned back on November 20, 2010:

Thanks Maureen. It was very scenic. Have a great time in Manchester.

This morning saw the coldest temperatures this season so far. Readings included: Albany: 18° Allentown: 20° Atlantic City: 21° Baltimore: 24° (old record: 25°, 1967, 1976, and 2003) Binghamton: 16° Boston: 28° Bridgeport: 22° (tied daily record set in 1971) Danbury: 15° (tied daily record set in 1992) Harrisburg: 24° Hartford: 20° Islip: 23° (tied daily record set in 1992) New Haven: 23° New York City: 27° Newark: 25° Philadelphia: 25° Poughkeepsie: 17° Providence: 22° Scranton: 19° Sterling, VA: 21° Washington, DC: 30° Westhampton: 14° (old record: 19°, 2003) White Plains: 20° Just before midnight, New York City's Central Park tied the November 8 record low temperature of 29°, which was set in 1886. Tonight will be warmer than last night and readings could the 50s in parts of the region tomorrow and especially Monday. However, even colder air mass than the current one will likely arrive later Tuesday. Following the frontal passage that brings in that cold shot, New York City could see one or two low temperatures in the lower or middle 20s. The minimum temperature Wednesday morning could challenge the Central Park daily record low temperature of 24°, which was set in 1986. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was +0.7°C for the week centered around October 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.67°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20. The SOI was -11.01 today. An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -1.428. Some of the more recent guidance shows the AO remaining strongly negative through the next two weeks. Such an outcome would increase prospects for at least some additional bouts of cold in the East after mid-month. On November 8, the MJO was in Phase 6 at an amplitude of 2.539 (RMM). The November 7-adjusted amplitude was 2.727. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Even as the second half of November will likely experience a pattern change to generally warmer than normal conditions, the magnitude of the cold during the first half of the month has made it very likely that November will finish with a cold anomaly in the region. 80% of the cases that saw New York City record a mean temperature below 46.0° during the first half of November went on to see 20" or more seasonal snowfall. Almost one quarter of such winters saw 40" or more snow. This data would suggest 20"-30" seasonal snowfall for the New York City area absent other variables (some of which could increase or reduce such amounts). Based on sensitivity analysis applied to the latest guidance, New York City has an implied 76% probability of experiencing a colder than normal November.

Gorgeous photo.

Despite mainly sunny skies, temperatures remained mainly in the upper 30s this afternoon in the New York Botanical Garden. In addition, the unseasonable cold brought down all the leaves of the Garden’s Ginkgo biloba trees before the leaves had turned a brilliant yellow. Some photos from around the Garden’s Lillian Goldman Fountain of Life, which was completed in 1905 by sculptor Charles Tefft.

The season's coldest air to date is now in place. At 8:51 pm, the temperature reached freezing for the first time this season in Central Park. Overnight, the mercury will likely reach the upper 20s in New York City. Moderation will occur this weekend, but an even colder air mass will likely arrive later Tuesday. Following the frontal passage that brings in that cold shot, New York City could see one or two low temperatures in the lower or middle 20s. The minimum temperature Wednesday morning could challenge the Central Park daily record low temperature of 24°, which was set in 1986. Readings may not return to normal and then above normal across the region until around November 20 +/- a few days. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was +0.7°C for the week centered around October 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.67°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20. The SOI was 0.00 today. The last time the SOI was 0.00 was February 4, 2016. An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -1.422. On November 7, the MJO was in Phase 5 at an amplitude of 2.731 (RMM). The November 6-adjusted amplitude was 2.576. Today's amplitude is the highest on record during November when the MJO was in Phase 5. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Even as the second half of November will likely experience a pattern change to warmer than normal conditions, the magnitude of the cold during the first half of the month has made it very likely that November will finish with a cold anomaly in the region. 80% of the cases that saw New York City record a mean temperature below 46.0° during the first half of November went on to see 20" or more seasonal snowfall. Almost one quarter of such winters saw 40" or more snow. This data would suggest 20"-30" seasonal snowfall for the New York City area absent other variables (some of which could increase or reduce such amounts). Based on sensitivity analysis applied to the latest guidance, New York City has an implied 75% probability of experiencing a colder than normal November. 　

The season's coldest air to date is now pushing into the region. Already, Binghamton (0.6"), Buffalo (0.6"), Rochester (0.3"), and Syracuse (0.2") have received their first measurable snowfall of winter 2019-20. Once the cold settles in, the pattern will remain generally cold for the next 10-14 days. Readings might not return to normal and then above normal across the region until around November 20 +/- a few days. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was +0.7°C for the week centered around October 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.67°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20. The SOI was +15.84 today. An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -1.498. On November 6, the MJO was in Phase 5 at an amplitude of 2.537 (RMM). The November 5-adjusted amplitude was 2.637. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Even as the second half of November will likely experience a pattern change to warmer than normal conditions, the magnitude of the cold during the first half of the month has made it very likely that November will finish with a cold anomaly in the region. 80% of the cases that saw New York City record a mean temperature below 46.0° during the first half of November went on to see 20" or more seasonal snowfall. Almost one quarter of such winters saw 40" or more snow. This data would suggest 20"-30" seasonal snowfall for the New York City area absent other variables (some of which could increase or reduce such amounts). Based on sensitivity analysis applied to the latest guidance, New York City has an implied 81% probability of experiencing a colder than normal November.

Based on the latest guidance, there is a growing chance that New York City will have a November 1-15 mean temperature below 44.0°. The last time that happened was November 1976 when New York City had a mean temperature of 42.1°. Since 1869, New York City has had only 11 cases where the November 1-15 temperature was below 44.0°.

A cold front, which will likely see a storm develop along the frontal boundary, will bring the season's coldest air mass so far this season into the region later this week. This air mass could be sufficiently cold to bring New York City its first freeze of the season. An area running from northeastern Pennsylvania across the New York State border eastward into New England will likely see measurable snowfall Thursday night into Friday. A portion of this area, including Binghamton, has the potential to pick up 2"-4" of snow. A second and potentially larger storm could impact parts of the regon next week. In part, due to what will likely become a strongly negative Arctic Oscillation, the second half warmup will likely be gradual. Readings might not return to normal and then above normal until around November 20 +/- a few days. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was +0.7°C for the week centered around October 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.67°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20. The SOI was -6.81 today. An SOI reading of -30 or below, as occurred on November 4-5, also occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -0.889. On November 5, the MJO was in Phase 5 at an amplitude of 2.632 (RMM). The November 4-adjusted amplitude was 2.572. The 2.567 amplitude is the highest amplitude on record in November for the MJO's being in Phase 5. The previous record was 2.572, which was set yesterday. Prior to this year, it was 2.512 on November 24, 2002. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Even as the second half of November will likely experience a pattern change to warmer than normal conditions, the magnitude of the cold during the first half of the month has made it very likely that November will finish with a cold anomaly in the region. The probability of such a warmup has increased according to some of the recent guidance. 80% of the cases that saw New York City record a mean temperature below 46.0° during the first half of November went on to see 20" or more seasonal snowfall. Almost one quarter of such winters saw 40" or more snow. This data would suggest 20"-30" seasonal snowfall for the New York City area absent other variables (some of which could increase or reduce such amounts). Based on sensitivity analysis applied to the latest guidance, New York City has an implied 77% probability of experiencing a colder than normal November.

A cold front, which will likely see a storm develop along the frontal boundary, will bring the season's coldest air mass so far this season into the region later this week. This air mass could be sufficiently cold to bring New York City its first freeze of the season. An area running from northeastern Pennsylvania across the New York State border eastward into New England will likely see measurable snowfall Thursday night into Friday. A portion of this area, including Binghamton, has the potential to pick up 4" or more snow. A second and potentially larger storm could impact parts of the regon next week. In part, due to a strongly negative Arctic Oscillation, the second half warmup will likely be gradual. Readings might not return to normal and then above normal until around November 20 +/- a few days. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was +0.7°C for the week centered around October 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.67°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20. Since 1981, approximately one out of every seven December cases involved a neutral ENSO. In general, a neutral ENSO in which Region 1+2 had a cold anomaly and Region 3.4 had a warm anomaly (as has been the case in the 6 week moving average) saw a warmer than normal December. Such neutral ENSO cases accounted for about 27% of all neutral ENSO December cases during the 1981-2018 period. This data does not consider blocking, as it is too soon to be confident about that factor in December. However, the greatest warmth coincided with a negative PDO while the coldest outcome coincided with a strongly positive PDO (+1.00 or above for December). Therefore, the first part of winter could start off milder than normal in the Middle Atlantic and southern New England regions. The SOI was -34.49 today. An SOI reading of -30 or below has occurred during three prior years in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -1.122. Since 1950, there have been five prior cases when the AO averaged -0.500 or below in both July and August: 1950, 1958, 1960, 1968, and 2015. The average temperature for September through November in New York City was 58.9° (59.6° adjusted). All cases featured a warmer than normal fall. There remains a potential for autumn 2019 to rank among the 30 warmest cases on record. For New York City, that would translate into a September-November mean temperature of at least 58.8°. On November 4, the MJO was in Phase 5 at an amplitude of 2.567 (RMM). The November 3-adjusted amplitude was 2.380. The 2.567 amplitude is the highest amplitude on record in November for the MJO's being in Phase 5. The previous record was 2.512 on November 24, 2002. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Even as the second half of November will likely experience a pattern change to warmer than normal conditions, the magnitude of the cold during the first half of the month has made it very likely that November will finish with a cold anomaly in the region. Since 1869, New York City has had 30 cases where the November 1-15 mean temperature averaged from 42.5°-46.5°. Just 2/30 (7%) wound up with a mean temperature greater than 46.5° (1934: 48.9° and 1991: 48.3°). None of the 35 cases where the November 1-15 had a mean temperature below 46.0° (including first half mean temperatures below 42.5°), which appears likely in 2019, finished with a monthly mean temperature above 46.5°. In addition, 80% of the cases that saw New York City record a mean temperature below 46.0° during the first half of November went on to see 20" or more seasonal snowfall. Almost one quarter of such winters saw 40" or more snow. Based on sensitivity analysis applied to the latest guidance, New York City has an implied 75% probability of experiencing a colder than normal November.

Tomorrow will feature above normal readings. However, an even colder air mass than the most recent one will likely arrive later this week. This air mass could be sufficiently cold to bring New York City its first freeze of the season. Some of the guidance continues to suggest the potential for the season's first snow in parts of the northern Mid-Atlantic and southern New England areas Thursday night or Friday. An area running from northeastern Pennsylvania across the New York State border eastward into New England has perhaps the greatest chance of seeing some accumulations. A portion of this area, including Binghamton, has the potential to pick up 4" or more snow. For New York City, 6/51 (12%) of the EPS ensembles show 1" or more snow. The following are percentages of EPS ensembles showing 1" or more snow at select locations: Allentown: 14%; Binghamton: 82%; Boston: 41%; Bridgeport: 22%; Harrisburg: 10%; Newark: 10%; Poughkeepsie: 39%; Scranton: 45%; and, White Plains: 16%. After mid-month, a prolonged period of above normal temperatures with some possibly much above normal temperatures could develop. Nevertheless, there remains uncertainty about the second half of the month. The possibility of a persistence of cold air from the first half of the month will need to be watched closely. The ENSO Region 1+2 anomaly was -0.4°C and the Region 3.4 anomaly was +0.7°C for the week centered around October 30. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.67°C and the ENSO Region 3.4 anomaly has averaged +0.58°C. A neutral ENSO is currently the base case for Winter 2019-20. Since 1981, approximately one out of every seven December cases involved a neutral ENSO. In general, a neutral ENSO in which Region 1+2 had a cold anomaly and Region 3.4 had a warm anomaly (as has been the case in the 6 week moving average) saw a warmer than normal December. Such neutral ENSO cases accounted for about 27% of all neutral ENSO December cases during the 1981-2018 period. This data does not consider blocking, as it is too soon to be confident about that factor in December. However, the greatest warmth coincided with a negative PDO while the coldest outcome coincided with a strongly positive PDO (+1.00 or above for December). Therefore, the first part of winter could start off milder than normal in the Middle Atlantic and southern New England regions. The SOI was -34.36 today. An SOI reading of -30 or below has occurred three times in the November 1-10 timeframe. All three cases featured a warmer than normal December. The average temperature for those three cases was 2 degrees warmer than normal. Today, the preliminary Arctic Oscillation (AO) figure was -1.060. Since 1950, there have been five prior cases when the AO averaged -0.500 or below in both July and August: 1950, 1958, 1960, 1968, and 2015. The average temperature for September through November in New York City was 58.9° (59.6° adjusted). All cases featured a warmer than normal fall. There remains a potential for autumn 2019 to rank among the 30 warmest cases on record. For New York City, that would translate into a September-November mean temperature of at least 58.8°. On November 3, the MJO was in Phase 5 at an amplitude of 2.367 (RMM). The November 2-adjusted amplitude was 2.149. Since 1974, there were 3 cases that saw the MJO in Phase 2 at an amplitude of 1.500 or above for at least 3 days during the October 15-25 period, as occurred this year: 1990, 2011, and 2015. All three cases featured a warmer than normal November in New York City and readings that were 3° or more above normal during the second half of November. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Even as the second half of November will likely experience a pattern change to warmer than normal conditions, possibly beginning a few days after mid-month, the depth of the cold during the first half of the month has made it likely that November will finish with a colder than normal anomaly in the region. Since 1869, New York City has had 30 cases where the November 1-15 mean temperature averaged from 42.5°-46.5°. Just 2/30 (7%) wound up with a mean temperature greater than 46.5° (1934: 48.9° and 1991: 48.3°). None of the 35 cases where the November 1-15 had a mean temperature below 46.0° (including first half mean temperatures below 42.5°), which appears likely in 2019, finished with a monthly mean temperature above 46.5°.

A brief period of milder conditions will develop after tomorrow. However, an even colder air mass than the current one could arrive later in the week. This air mass could be sufficiently cold to bring New York City its first freeze of the season. Some of the guidance continues to suggest the potential for the season's first snow in parts of the northern Mid-Atlantic and southern New England areas Thursday night or Friday. The area to the north and west of New York City and Newark, from northeastern Pennsylvania eastward into New England has perhaps the greatest chance of seeing some accumulations. A portion of this area has the potential to pick up 4" or more snow. For New York City, 14/51 (27%) of the EPS ensembles show 1" or more snow. The following are percentages of EPS ensembles showing 1" or more snow at select locations: Allentown: 33%; Binghamton: 78%; Boston: 49%; Bridgeport: 37%; Harrisburg: 22%; Newark: 20%; Poughkeepsie: 55%; Scranton: 63%; and, White Plains: 35%. All of these probabilities represent an increase from yesterday's 12z EPS. After mid-month, a prolonged period of above normal temperatures with some possibly much above normal temperatures could develop. Nevertheless, there remains uncertainty about the second half of the month. The possibility of a persistence of cold air from the first half of the month will need to be watched closely. Repeated runs of the GFS have been most insistent about a persistence of the cold. Should the Arctic Oscillation go as severely negative as forecast by some of the GFS ensemble members, the probability of such a scenario of a delayed return of warmer conditions could increase. The ENSO Region 1+2 anomaly was -1.3°C and the Region 3.4 anomaly was +0.6°C for the week centered around October 23. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.82°C and the ENSO Region 3.4 anomaly has averaged +0.43°C. A neutral ENSO is currently the base case for Winter 2019-20. Since 1981, approximately one out of every seven December cases involved a neutral ENSO. In general, a neutral ENSO in which Region 1+2 had a cold anomaly and Region 3.4 had a warm anomaly (as has been the case in the 6 week moving average) saw a warmer than normal December. Such neutral ENSO cases accounted for about 27% of all neutral ENSO December cases during the 1981-2018 period. This data does not consider blocking, as it is too soon to be confident about that factor in December. However, the greatest warmth coincided with a negative PDO while the coldest outcome coincided with a strongly positive PDO (+1.00 or above for December). Therefore, the first part of winter could start off milder than normal in the Middle Atlantic and southern New England regions. The SOI was -10.31 today. Today, the preliminary Arctic Oscillation (AO) figure was -0.101. Since 1950, there have been five prior cases when the AO averaged -0.500 or below in both July and August: 1950, 1958, 1960, 1968, and 2015. The average temperature for September through November in New York City was 58.9° (59.6° adjusted). All cases featured a warmer than normal fall. There remains a potential for autumn 2019 to rank among the 30 warmest cases on record. For New York City, that would translate into a September-November mean temperature of at least 58.8°. On November 2, the MJO was in Phase 5 at an amplitude of 2.139 (RMM). The November 1-adjusted amplitude was 1.839. Since 1974, there were 3 cases that saw the MJO in Phase 2 at an amplitude of 1.500 or above for at least 3 days during the October 15-25 period, as occurred this year: 1990, 2011, and 2015. All three cases featured a warmer than normal November in New York City and readings that were 3° or more above normal during the second half of November. The MJO's move into Phase 5 at a high amplitude reinforces the idea of a warmer to perhaps much warmer than normal second half of November. Since 1974, there were 3 cases that saw the MJO in Phase 5 at an amplitude of 1.500 or above for at least 2 days during the November 1-10 period. The November 16-30 temperature averaged 46.1° (0.2° above normal). However, when the case that had a cooler than normal September was excluded, the mean temperature was 49.1° (3.2° above normal). September 2019 had a mean temperature of 70.4°, which was 2.4° above normal. Based on the above data, the base case remains a warmer than normal November. However, any warm anomaly will be much smaller than the October one. The ultimate outcome will depend, in large part, on the cold anomaly for the first half of November.