donsutherland1

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.

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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).

No. There is almost no correlation for New York City (Central Park: 1980-2020). The coefficient determination between whether May had a 90° day and the number of June 90° days is approximately 0.03. The coefficient of determination between the number of 90° days in May and number of 90° days in June is about 0.04. Since 1980, New York City has averaged 1.0 90° day in May and 2.9 90° days in June. When May had no 90° days, the June average was 2.5 days (minimum: 0 days; maximum: 6 days). When May had 1 or more 90° days, the June average was 3.4 days (minimum: 0 days; maximum: 9 days).

Morning thoughts... Today will be variably cloudy and somewhat cooler. Temperatures will likely reach the lower to perhaps middle 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 74° Newark: 76° Philadelphia: 73° Tomorrow will be partly cloudy with high temperatures again reaching the lower 70s in most places. As the PNA plunges to abnormally low levels for May, an impressive warmup could develop later this week.

The dominant weather story over the 7-10 days 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. For the first time, the guidance has "noticed" the big change in the PNA and has swung toward a dramatically warmer outcome. The implied probability of a cooler than normal May was 55% yesterday. Today, there is an implied 65% probability of a warmer than normal May. More immediately, temperatures will likely top out in the 70s in much of the region through the weekend. A minor push of slightly cooler air is possible early next week before a more impressive warmup unfolds. 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 +25.83 today. The preliminary Arctic Oscillation (AO) figure was -0.201 today. On May 13 the MJO was in Phase 2 at an amplitude of 0.909 (RMM). The May 12-adjusted amplitude was 0.885 (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 65% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.0° (0.8° above normal).

Under partly to mostly sunny skies, the temperature soared into the upper 70s early this afternoon in the New York City area. Peonies and ornamental onions are now in full bloom in the New York Botanical Garden.

Overnight, one saw about as big a swing in the guidance as one ever sees. The guidance has finally come into line with the strong PNA- that is now developing.

Morning thoughts... Today will be partly to mostly sunny and warm. Temperatures will likely reach the middle 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 77° Newark: 79° Philadelphia: 77° Tomorrow will be variably cloudy and still warm. As the PNA plunges to abnormally low levels for May, an impressive warmup could develop next week.

Here’s a new paper on this subject: https://www.cell.com/one-earth/fulltext/S2590-3322(21)00233-5?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2590332221002335%3Fshowall%3Dtrue

Temperatures will likely top out in the 70s in much of the region through the weekend. A minor push of slightly cooler air is possible early next week before a potentially more impressive warmup unfolds. 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 current PNA forecast provides a fresh hint of a noticeably warmer end to the month. The PNA is currently forecast by most ensemble members to fall to -1.000 or below during the second half of May. 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. 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 +17.33 today. The preliminary Arctic Oscillation (AO) figure was -0.526 today. On May 12 the MJO was in Phase 2 at an amplitude of 0.886 (RMM). The May 11-adjusted amplitude was 1.011 (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 55% probability that New York City will have a cooler than normal May (1991-2020 normal). May will likely finish with a mean temperature near 62.5° (0.7° below normal).

Thanks. It seems to be a larger issue than simply an Upton website matter, in that case. Perhaps the Eastern Region or even NCEP was having issues.

Perhaps it was a temporary issue, but it seems to have been occurring at least sporadically during the past few days.

Does anyone know if there are website issues with the NWS point-and-click site for New York City? This is the 3rd consecutive day that the afternoon figure is far off what is likely and what is already occurring. Yesterday, when I tried to view the preliminary daily climate summary, there was an error retrieving it. Later on, it worked fine. I'm not sure if the issue I encountered yesterday is part of a larger issue that is preventing or delaying the timely updates to the point-and-click numbers or a separate unrelated problem with coincidental timing.

Morning thoughts... Today will be partly to mostly sunny and warm. Temperatures will likely reach the middle 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 76° Newark: 78° Philadelphia: 75° Tomorrow will be fair and continued warm. The potential exists for the last week of May to see above to much above normal temperatures. During the 1981-2010 period, New York City averaged 0.9 days on which the temperature reached 90° or above during May. During the 1991-2020 period, that figure rose slightly to 1.0 days.

Temperatures will likely top out in the 70s in much of the region through the weekend. A minor push of slightly cooler air is possible early next week before a potentially more impressive warmup unfolds. 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 PNA has just gone negative with a preliminary value of -0.529 today. The current PNA forecast provides a fresh hint of a noticeably warmer end to the month. The PNA is currently forecast by most ensemble members to fall to -1.000 or below during the second half of May. 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. 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 +8.90 today. The preliminary Arctic Oscillation (AO) figure was -0.373 today. On May 11 the MJO was in Phase 3 at an amplitude of 1.011 (RMM). The May 10-adjusted amplitude was 1.276 (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 64% probability that New York City will have a cooler than normal May (1991-2020 normal). May will likely finish with a mean temperature near 62.2° (1.0° below normal).

Morning thoughts... Today will be partly sunny and mild. Temperatures will likely reach the lower 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 71° Newark: 73° Philadelphia: 71° Tomorrow will be fair and warm.

A gradual warming trend will likely commence starting tomorrow. For the remainder of the week, temperatures will likely top out in the 70s in much of the region. 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 comination 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 current PNA forecast provides a fresh hint of a noticeably warmer end to the month. The PNA is currently forecast by most ensemble members to fall to -1.000 or below during the second half of May. 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. 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-cool ENSO conditions are now developing. Neutral ENSO conditions will likely be in place by the end of spring. The SOI was +5.53 today. The preliminary Arctic Oscillation (AO) figure was -0.282 today. On May 10 the MJO was in Phase 3 at an amplitude of 1.275 (RMM). The May 9-adjusted amplitude was 1.296 (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 61% probability that New York City will have a cooler than normal May (1991-2020 normal). May will likely finish with a mean temperature near 62.2° (1.0° below normal).