donsutherland1

The temperature rose into the upper 80s and lower 90s across much of the region today. 90° or above temperatures were reported at: Atlantic City: 94° (old record: 91°, 1992) Baltimore: 93° Georgetown, DE: 93° (old record: 92°, 1996) Hartford: 90° Islip: 90° New York City-JFK: 94° (tied record set in 1992) Newark: 96° Philadelphia: 92° Washington, DC: 91° Wilmington, DE: 92° The high temperature at Central Park was 89°. Today was the first day on record in May where Central Park had a temperature below 90° while Islip had a high temperature of 90° or above. It was also the first day on record where Central Park had a high temperature below 90° and both Islip and JFK Airport saw 90° or above high temperatures. Prior to today, there were two cases in May where JFK Airport had a high temperature of 90° or above while Central Park did not reach 90°: May 13, 1956: JFK: 90°; NYC: 89° May 21, 1962: JFK: 90°; NYC: 87° Bridgeport reached 87°. That broke the daily record of 85°, which was set in 1991 and tied in 1992. Tomorrow will feature more unseasonable warmth. Temperatures will generally reach the upper 80s and lower 90s across much of the region. Exceptions would be coastal areas prone to sea breezes. The dominant weather story into the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. There will likely be additional days on which the temperature will make a run at 90° in parts of the region. Today, the preliminary value of the PNA was -1.519. The PNA is forecast to remain at or below -1.000 until around May 24. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia. During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above. As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013. The first 7-10 days of June could also start off warmer than normal. The MJO's passage through Phase 4 at an amplitude of 1.500 or above during the May 15-25 period coupled with ENSO Region 1+2 temperature anomalies above -1.0°C and below +1.0°C, as has been the case this year, has typically seen warmth in the East during the first 10 days of June. Cooler conditions typically prevailed when the ENSO Region 1+2 anomalies were outside that range. Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.3°C for the week centered around May 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.75°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was +1.63 today. The preliminary Arctic Oscillation (AO) figure was +1.092 today. On May 20 the MJO was in Phase 4 at an amplitude of 1.863 (RMM). The May 19-adjusted amplitude was 1.915 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. 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 May (1991-2020 normal). May will likely finish with a mean temperature near 64.6° (1.4° above normal).

The high temperature at Central Park was 89°. Today was the first day on record in May where Central Park had a temperature below 90° while Islip had a high temperature of 90° or above. It was also the first day on record where Central Park had a high temperature below 90° and both Islip and JFK Airport saw 90° or above high temperatures. Prior to today, there were two cases in May where JFK Airport had a high temperature of 90° or above while Central Park did not reach 90°: May 13, 1956: JFK: 90°; NYC: 89° May 21, 1962: JFK: 90°; NYC: 87°

Despite high- and mid-level clouds that dimmed the sun, the temperature rose into the upper 80s in the New York City area and lower 90s in adjacent New Jersey. Peonies remain in bloom at the New York Botanical Garden. Irises have exploded into bloom.

1906 9 days 1908 12 days

Morning thoughts... Today will be partly sunny and hot. Temperatures will likely reach the upper 80s to lower 90s in most of the region. A few areas could experience an afternoon or evening thundershower. Likely high temperatures around the region include: New York City (Central Park): 90° Newark: 93° Philadelphia: 91° Tomorrow will be another partly sunny and very warm day.

It was probably a combination of the increased urbanization around LGA--now New York City's premier heat island--and the more recent increase in vegation in Central Park. As a result, the relationship between the two locations weakened as far as 90° days was concerned. Annual 90° Days (30-Year Average): 1951-80: LGA: 14.8; NYC: 18.3 1961-90: LGA: 13.7; NYC: 18.3 1971-00: LGA: 15.1; NYC: 18.1 1981-10: LGA: 18.7; NYC: 17.4 1991-20: LGA: 21.8; NYC: 17.4 The 30-year average for annual 90° days at LGA surpassed NYC for the first time during the 1978-2007 period. Annual 90° Days (1950-2020 broken into two parts): 1950-1984: LGA: 14.7; NYC: 18.0 (coefficient of determination: 0.686) 1985-2020: LGA: 21.0; NYC: 17.5 (coefficient of determination: 0.619)

MPO has not yet hit 90.

It’s a little above that.

Temperatures in the northern Middle Atlantic and southern New England areas rose into the 70s and 80s today. Some 90° temperatures were reported. Burlington reached 90° for the second consecutive day and second time this month. Only 10 years saw May record 2 or more 90° temperatures and 9 years saw 2 or more consecutive such temperatures in May. The last time there were 2 or more 90° readings in May and 2 or more consecutive such temperatures was 2020. Syracuse reached 93°. 90° Days for Select Cities (through May 21): Albany: 0 (2020: 13 days; 5-Year Average: 13.6 days) Allentown: 0 (2020: 24 days; 5-Year Average: 27.6 days) Baltimore: 0 (2020: 46 days; 5-Year Average: 44.6 days) Boston: 0 (2020: 14 days; 5-Year Average: 17.2 days) Bridgeport: 0 (2020: 11 days; 5-Year Average: 13.4 days) Burlington: 2 (2020: 20 days; 5-Year Average: 13.0 days) Harrisburg: 0 (2020: 35 days; 5-Year Average: 30.6 days) Hartford: 0 (2020: 39 days; 5-Year Average: 29.0 days) Islip: 0 (2020: 8 days; 5-Year Average: 9.4 days) New York City-JFK: 0 (2020: 12 days; 5-Year Average: 10.2 days) New York City-LGA: 0 (2020: 34 days; 5-Year Average: 29.4 days) New York City-NYC: 0 (2020: 20 days; 5-Year Average: 18.2 days) Newark: 1 (2020: 31 days; 5-Year Average: 31.2 days) Philadelphia: 0 (2020: 36 days; 5-Year Average: 34.6 days) Scranton: 1 (2020: 25 days; 5-Year Average: 16.4 days) Washington, DC: 1 (2020: 46 days; 5-Year Average: 50.8 days) New York City-Newark Average: 0 (2020: 22 days) ...Expected: 0 (based on regression equation tied to JFK-LGA-EWR data) In Quebec, daily record high temperatures were set in Montreal: 89° (old record: 87°, 1977) and Trois-Rivières: 84° (old record: 79°, 2012) Much warmer weather is likely for the weekend. Temperatures will generally reach the upper 80s and lower 90s across much of the region. Exceptions would be coastal areas prone to sea breezes. The dominant weather story into at least the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. There will likely be additional days on which the temperature will make a run at 90° in parts of the region. Today, the preliminary value of the PNA was -1.457. The PNA is forecast to remain at or below -1.000 until around May 24. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia. During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above. As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013. The first 7-10 days of June could also start off warmer than normal. The MJO's passage through Phase 4 at an amplitude of 1.500 or above during the May 15-25 period coupled with ENSO Region 1+2 temperature anomalies above -1.0°C and below +1.0°C, as has been the case this year, has typically seen warmth in the East during the first 10 days of June. Cooler conditions typically prevailed when the ENSO Region 1+2 anomalies were outside that range. Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.3°C for the week centered around May 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.75°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was +0.86 today. The preliminary Arctic Oscillation (AO) figure was -0.024 today. On May 19 the MJO was in Phase 4 at an amplitude of 1.914 (RMM). The May 18-adjusted amplitude was 1.703 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. 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 May (1991-2020 normal). May will likely finish with a mean temperature near 64.7° (1.5° above normal).

The increased fraction of flooded area likely included some important and costly infrastructure.

Morning thoughts... Today will be partly to mostly sunny and warm. Temperatures will likely reach the upper 70s to lower 80s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 79° Newark: 83° Philadelphia: 84° A much warmer weekend lies ahead.

Despite ample sunshine, the northern Middle Atlantic and southern New England regions were cooler than yesterday. Nevertheless, a few locations reached 90° in the Northeast this afternoon. Those locations included: Burlington: 92° (old record: 91°, 1975); Scranton: 90°; and, Washington, DC: 93°. 90° temperatures at Burlington have become more common during the month of May in recent years. Some statistics for May 1981-2020: 1981-2010: Mean Monthly High: 85.2°; 0.3 90° days each May 1991-2020: Mean Monthly High: 86.3°; 0.4 90° days each May 2010-2020: Mean Monthly High: 88.5°; 0.8 90° days each May Tomorrow will be fair and pleasant in the northern Middle Atlantic and southern New England areas with temperatures holding mainly in the 70s. Lower 80s are possible in central and southern New Jersey southward. Much warmer weather is likely for the weekend. The dominant weather story into at least the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. There will likely be additional days on which the temperature will make a run at 90° in parts of the region. Today, the preliminary value of the PNA was -1.584. The PNA is forecast to remain at or below -1.000 until around May 24. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia. During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above. As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013. Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.3°C for the week centered around May 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.75°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was +8.14 today. The preliminary Arctic Oscillation (AO) figure was -0.587 today. On May 18 the MJO was in Phase 3 at an amplitude of 1.702 (RMM). The May 17-adjusted amplitude was 1.749 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. 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 May (1991-2020 normal). May will likely finish with a mean temperature near 64.6° (1.4° above normal).

It reached a daily record 92 today.

Morning thoughts... Today will be partly to mostly sunny and very warm. Temperatures will likely reach the middle and upper 70s in most of the region. Temperatures will likely reach the lower 80s from central New Jersey southward. Likely high temperatures around the region include: New York City (Central Park): 76° Newark: 78° Philadelphia: 83° Tomorrow will be partly cloudy and mild.

Nothing that I can recall anytime recently. Unfortunately, model data isn’t archived—at least publicly—so one can’t look for such dramatic swings.

The temperature soared into the middle and upper 80s in most of the region today. Newark was the region's hot spot with a high temperature of 91°. At Chibougamau, QC, the temperature reached 83°. That broke the daily record high temperature of 80°, which was set in 2010. Tomorrow and Friday will be fair and cooler in the northern Middle Atlantic and southern New England areas with temperatures holding mainly in the 70s. Lower 80s are possible in central and southern New Jersey southward. The dominant weather story into at least the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. There will likely be additional days where the temperature makes a run at 90° in parts of the region. Today, the preliminary value of the PNA was -1.662. That was lowest figure since March 31 when the PNA was -1.775. That was also the lowest figure in May since May 31, 2018 when the PNA was -1.767. The PNA is forecast to remain at or below -1.000 until around May 24. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia. During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above. As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013. Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.3°C for the week centered around May 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.75°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was +6.22 today. The preliminary Arctic Oscillation (AO) figure was -0.840 today. On May 17 the MJO was in Phase 3 at an amplitude of 1.750 (RMM). The May 16-adjusted amplitude was 1.654 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. Based on sensitivity analysis applied to the latest guidance, there is an implied 76% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.4° (1.2° above normal).

As has been a frequent occurrence at Central Park in recent years, the temperature dropped somewhat during mid-afternoon before rising again. That is almost certainly the result of the interaction between the sun's angle and the thick vegetation around the Park's ASOS. Meanwhile, Newark reached 90° for the first time this year.

Parts of the region will likely reach or exceed 90° today. Data for 90° days for select cities is below: Allentown: 2020: 24 days 1991-2020 average: 18.2 days Least: 1 day, 1960 Most: 41 days, 1966 Bridgeport: 2020: 11 days 1991-2020 average: 9.1 days Least: 0 days, 1950, 1962, and 2004 Most: 18 days, 2010 and 2016 Islip: 2020: 8 days 1991-2020 average: 8.3 days Least: 0 days, 1967, 1979, 2004, and 2014 Most: 18 days, 1999 New York City-JFK: 2020: 12 days 1991-2020 average: 10.8 days Least: 0 days, 1967 Most: 32 days, 2010 New York City-LGA: 2020: 34 days 1991-2020 average: 21.8 days Least: 4 days, 1972 and 1978 Most: 48 days, 2010 New York City-NYC: 2020: 20 days 1991-2020 average: 17.4 days Least: 1 day, 1902 Most: 39 days, 1991 and 1993 Newark: 2020: 31 days 1991-2020 average: 28.3 days Least: 7 days, 1967 Most: 54 days, 2010 Philadelphia: 2020: 36 days 1991-2020 average: 29.7 days Least: 5 days, 1889 Most: 55 days, 2010

Morning thoughts... Today will be partly to mostly sunny and very warm. Temperatures will likely reach the middle and upper 80s in most of the region. A few locations could reach or exceed 90°. Likely high temperatures around the region include: New York City (Central Park): 88° Newark: 90° Philadelphia: 90° Tomorrow will be partly cloudy and cooler.

New study: Approximately $8.1 billion of the damages that resulted from Sandy (2012) can be attributed to rising sea levels on account of anthropogenic climate change. The paper can be found here: https://www.nature.com/articles/s41467-021-22838-1

Tomorrow will be partly to mostly sunny and very warm. Parts of the region could reach 90° for the first time this year. The dominant weather story into at least the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. Today, the preliminary value of the PNA was -1.589. That was lowest figure since March 31 when the PNA was -1.775. That was also the lowest figure in May since May 31, 2018 when the PNA was -1.767. The PNA is forecast to remain at or below -1.000 until at least May 24. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia. During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above. As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013. Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.3°C for the week centered around May 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.75°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was -1.44 today. The preliminary Arctic Oscillation (AO) figure was -0.607 today. On May 16 the MJO was in Phase 2 at an amplitude of 1.655 (RMM). The May 15-adjusted amplitude was 1.212 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. Based on sensitivity analysis applied to the latest guidance, there is an implied 73% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.3° (1.1° above normal).

Morning thoughts... Today will be partly to mostly sunny and very warm. Temperatures will likely reach the middle and upper 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 83° Newark: 85° Philadelphia: 82° Tomorrow will be fair and unseasonably warm.

Under bright sunshine, thermometers rose into the upper 70s and even lower 80s in a few places. Even warmer days lie ahead over the next week or two. At the height of the warmth, the 90° isotherm could reach parts of the Middle Atlantic region. The dominant weather story into at least the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. Today, the preliminary value of the PNA was -1.291. That was lowest figure since April 1 when the PNA was -1.380. The PNA is forecast to fall further and then remain at or below -1.000 until at least May 24. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia. During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above. As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013. Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.3°C for the week centered around May 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.75°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was +9.75 today. The preliminary Arctic Oscillation (AO) figure was -0.266 today. On May 15 the MJO was in Phase 2 at an amplitude of 1.212 (RMM). The May 14-adjusted amplitude was 0.924 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. Based on sensitivity analysis applied to the latest guidance, there is an implied 71% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.3° (1.1° above normal).

Morning thoughts... Today will be partly to mostly sunny and warm. Temperatures will likely reach the middle and upper 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 78° Newark: 79° Philadelphia: 78° Tomorrow will be fair and somewhat warmer.

A minor push of slightly cooler air is possible early this week before an impressive warmup unfolds. At the height of the warmth, the 90° isotherm could reach parts of the Middle Atlantic region. The dominant weather story into at least the closing week of May will be the development of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. The PNA is currently forecast by most ensemble members to fall to -1.000 or below during the second half of May and remain there for perhaps a week or more. During the 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia. During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above. As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013. Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.7°C and the Region 3.4 anomaly was -0.4°C for the week centered around May 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.83°C and the ENSO Region 3.4 anomaly has averaged -0.42°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was +22.23 today. The preliminary Arctic Oscillation (AO) figure was -0.061 today. On May 14 the MJO was in Phase 2 at an amplitude of 0.924 (RMM). The May 13-adjusted amplitude was 0.910 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. Based on sensitivity analysis applied to the latest guidance, there is an implied 73% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.3° (1.1° above normal).