donsutherland1

Morning thoughts... At 8 am, moderate rainfall was moving through area that included parts of Virginia, Maryland, Delaware, Pennsylvania and New Jersey. Another smaller area of moderate rainfall was moving through parts of the Hudson Valley. In New York City, light rain was falling with a temperature of 67 degrees. A moderate to heavy rainfall remains likely parts of the Middle Atlantic region. Virginia, Maryland, Delaware, Pennsylvania and southern New Jersey could be in line for 1”-2” rain with locally higher amounts. Parts of Long Island could see 0.50”-1.00” rain. New York City will likely see less than 0.50”. Out west, intense heat will again sear parts of California, Arizona and Nevada. Death Valley is poised to challenge the August heat record. Yesterday’s high temperature there was 126 degrees, which beat the daily record of 124 degrees from 2002. Yesterday’s high temperature was just below the monthly record of 127 degrees, which was set on August 12, 1933 and tied on August 1, 2017.

Under partly sunny skies, temperatures reached the upper 70s and lower 80s in much of the region. Coastal areas saw a stiff northeast breeze. Out west, extreme heat prevailed in the Southwest. Select high temperatures included: Death Valley, CA: 125° (old record: 124°, 2002) Kingman, AZ: 111° (old record: 106°, 1933) ***Tied August Record*** Lake Havasu City, AZ: 120° (old record: 118°, 1994) Las Vegas: 113° (old record: 111°, 1939, 1994 and 2002) Mesa, AZ: 112° (tied daily record set in 2019) Needles, CA: 123° (old record: 118°, 2019) ***New August Record*** Phoenix: 114° Tucson: 109° Yuma, AZ: 111° Final figures will be available for Death Valley and Lake Havasu City tomorrow. More intense heat is likely in that region through midweek next week. Tomorrow could see some showers and perhaps periods of rain with readings mainly in the 70s. From southern New Jersey southward to Virginia, a soaking rain is in store. There, widespread 1"-2" with locally higher amounts is likely. A moderate rainfall of 0.50"-1.00" is possible on portions of Long Island. Nevertheless, the current predominantly warmer than normal pattern will likely persist through much of September, paving the way for a solidly warmer than normal summer and a warm start to fall throughout the region. Occasional short-lived cool shots remain possible. The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -0.6°C for the week centered around August 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.15°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions will likely develop. The SOI was +5.46. Today, the preliminary Arctic Oscillation (AO) figure was -0.097. On August 14, the MJO was in Phase 8 at an amplitude of 0.836 (RMM). The August 13-adjusted amplitude was 0.617. The MJO's recent passage through Phase 4 at an amplitude of 1.500 or above has been uncommon during the first half of August. During the 1981-2019 period only 1983 and 2019 saw the MJO move through Phase 4 with an amplitude of 1.500 or above during the first half of August. August 1983 had the longest such stretch. Both cases saw the second half of August average generally warmer than normal in the Middle Atlantic region. Both cases also featured a warmer than normal September. Last year, the MJO went through a very strong passage through Phase 1 during the closing days of May. About four weeks later, a warmer than normal pattern locked in and predominated through early autumn. This year, the MJO was in Phase 1 for 3 consecutive days with an amplitude of 1.500 or above during the June 1-3 period. Last year, the SOI fell to -42.04 on June 22 when the MJO was in Phase 6. This year, the SOI plunged below -46.68 on June 5, its lowest level in more than three years. The dramatic plunge in the SOI could be the proverbial spark that kicks off a sequence of events leading to the development of a sustained warmer than normal period. The cases that saw both the MJO and SOI thresholds satisfied generally saw 10-20 days where the temperature reached or exceeded 90° in New York City during the July 1-August 31 period. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Overall, the evolution of ENSO, along with the observed ongoing monthly warming (1.6°/decade in NYC and 1.5°/decade in the Northeast Region during September 1990-2019), favors a warmer than normal September. Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. 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 August. August will likely finish with a mean temperature near 77.0°.

Morning thoughts... Readings will generally rise into the lower 80s across the region today. Some areas could top out in the middle 80s. Tomorrow, a system will bring a moderate to heavy rainfall to parts of the Middle Atlantic region. Virginia, Maryland, Delaware, Pennsylvania and southern New Jersey could be in line for 1”-2” rain with locally higher amounts. There is uncertainty how far north the steady rain will come. New York City could see only showers and perhaps a period of rain if the ECMWF is accurate. Out west, a period of intense heat will be searing parts of California, Arizona and Nevada. Death Valley is poised to challenge the August heat record. Yesterday’s high temperature there was 124 degrees, which was just below the daily record of 125 degrees from 1996. That was the hottest August temperature since the mercury hit 127 degrees on August 1, 2017. Today through Tuesday should be several degrees warmer. The August record is 127 degrees. That record was set on August 12, 1933 and tied on August 3, 1993 and August 1, 2017. Earlier this summer, Death Valley recorded a 128-degree high temperature on July 12. That was Death Valley’s highest temperature since July 4, 2013 when the thermometer also reached 128 degrees.

Temperatures rose into the middle and, in places, upper 80s today. Tomorrow will be cooler with highs in the lower 80s. Sunday could see some showers and perhaps periods of rain with readings mainly in the 70s. Nevertheless, the current predominantly warmer than normal pattern will likely persist through much of September, paving the way for a solidly warmer than normal summer and a warm start to fall throughout the region. Occasional short-lived cool shots remain possible. The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -0.6°C for the week centered around August 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.15°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions will likely develop. The SOI was +1.76. Today, the preliminary Arctic Oscillation (AO) figure was -0.181. On August 13, the MJO was in Phase 7 at an amplitude of 0.618 (RMM). The August 12-adjusted amplitude was 0.327. Some of the guidance suggests that the MJO could be in Phase 8 in late August. The convergence of the MJO's passage through phase 8 and revived tropical cyclone activity could suggest the possibility of an East Coast threat during the August 20-September 10 period. Phases 8-1-2 have coincided with a cluster of East Coast landfalls. Belle (1976) and Gloria (1985) made landfall when the MJO was in Phase 8 at a low amplitude. Sandy (2012) and Fay (2020) made landfall when the MJO was in Phase 2. The MJO's recent passage through Phase 4 at an amplitude of 1.500 or above has been uncommon during the first half of August. During the 1981-2019 period only 1983 and 2019 saw the MJO move through Phase 4 with an amplitude of 1.500 or above during the first half of August. August 1983 had the longest such stretch. Both cases saw the second half of August average generally warmer than normal in the Middle Atlantic region. Both cases also featured a warmer than normal September. Last year, the MJO went through a very strong passage through Phase 1 during the closing days of May. About four weeks later, a warmer than normal pattern locked in and predominated through early autumn. This year, the MJO was in Phase 1 for 3 consecutive days with an amplitude of 1.500 or above during the June 1-3 period. Last year, the SOI fell to -42.04 on June 22 when the MJO was in Phase 6. This year, the SOI plunged below -46.68 on June 5, its lowest level in more than three years. The dramatic plunge in the SOI could be the proverbial spark that kicks off a sequence of events leading to the development of a sustained warmer than normal period. The cases that saw both the MJO and SOI thresholds satisfied generally saw 10-20 days where the temperature reached or exceeded 90° in New York City during the July 1-August 31 period. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Overall, the evolution of ENSO, along with the observed ongoing monthly warming (1.6°/decade in NYC and 1.5°/decade in the Northeast Region during September 1990-2019), favors a warmer than normal September. Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. 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 August. August will likely finish with a mean temperature near 77.0°.

With today's rainfall, New York City has received 26.28" precipitation this year. That is 4.50" below normal. Based on the 1971-2019 data, there is an implied 83% probability that New York City will receive 40" or more precipitation this year. However, there is just an implied 23% probability that it will receive at least 50" precipitation. The high temperature will rise into the lower to middle 80s tomorrow and then the upper 70s and lower 80s during the coming weekend. Nevertheless, the current predominantly warmer than normal pattern will likely persist through much of September, paving the way for a solidly warmer than normal summer and a warm start to fall throughout the region. Occasional short-lived cool shots remain possible. The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -0.6°C for the week centered around August 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.15°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions will likely develop. The SOI was -5.95. Today, the preliminary Arctic Oscillation (AO) figure was -0.332. On August 12, the MJO was in Phase 6 at an amplitude of 0.328 (RMM). The August 11-adjusted amplitude was 0.421. Some of the guidance suggests that the MJO could be in Phase 8 in late August. The convergence of the MJO's passage through phase 8 and revived tropical cyclone activity could suggest the possibility of an East Coast threat during the August 20-September 10 period. Phases 8-1-2 have coincided with a cluster of East Coast landfalls. Belle (1976) and Gloria (1985) made landfall when the MJO was in Phase 8 at a low amplitude. Sandy (2012) and Fay (2020) made landfall when the MJO was in Phase 2. The MJO's recent passage through Phase 4 at an amplitude of 1.500 or above has been uncommon during the first half of August. During the 1981-2019 period only 1983 and 2019 saw the MJO move through Phase 4 with an amplitude of 1.500 or above during the first half of August. August 1983 had the longest such stretch. Both cases saw the second half of August average generally warmer than normal in the Middle Atlantic region. Both cases also featured a warmer than normal September. Last year, the MJO went through a very strong passage through Phase 1 during the closing days of May. About four weeks later, a warmer than normal pattern locked in and predominated through early autumn. This year, the MJO was in Phase 1 for 3 consecutive days with an amplitude of 1.500 or above during the June 1-3 period. Last year, the SOI fell to -42.04 on June 22 when the MJO was in Phase 6. This year, the SOI plunged below -46.68 on June 5, its lowest level in more than three years. The dramatic plunge in the SOI could be the proverbial spark that kicks off a sequence of events leading to the development of a sustained warmer than normal period. The cases that saw both the MJO and SOI thresholds satisfied generally saw 10-20 days where the temperature reached or exceeded 90° in New York City during the July 1-August 31 period. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Overall, the evolution of ENSO, along with the observed ongoing monthly warming (1.6°/decade in NYC and 1.5°/decade in the Northeast Region during September 1990-2019), favors a warmer than normal September. Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. Based on sensitivity analysis applied to the latest guidance, there is an implied 70% probability that New York City will have a warmer than normal August. August will likely finish with a mean temperature near 77.0°.

Morning thoughts... At 9:20 am, a cluster of slow-moving thunderstorms was approaching Newark. It was also expanding eastward, meaning that a shower or thundershower could occur in New York City this morning. Further north, several hours of sunshine should be the rule in such areas as Poughkeepsie. Much of the region will likely see temperatures top out in the lower and middle 80s.

Yes, it’s a meta analysis.

Temperatures reached the upper 80s and lower 90s across the region today. In addition, scattered heavy thunderstorms brought drenching rains to parts of the area. Philadelphia picked up 1.44" rain and New York City received 1.76" rain. 90° Days for Select Cities (through August 12): Albany: 13 (2019: 12 days) Allentown: 23 (2019: 24 days) Baltimore: 40 (2019: 59 days) Boston: 14 (2019: 15 days) Burlington: 20 (2019: 8 days) Harrisburg: 29 (2019: 33 days) Islip: 6 (2019: 8 days) New York City-JFK: 10 (2019: 7 days) New York City-LGA: 30 (2019: 26 days) New York City-NYC: 18 (2019: 15 days) Newark: 27 (2019: 28 days) Philadelphia: 32 (2019: 35 days) Scranton: 23 (2019: 12 days) Washington, DC: 41 (2019: 62 days) New York City-Newark Average: 21 (2019: 19 days) ...Expected: 21 (based on regression equation tied to JFK-LGA-EWR data) The next several days will be somewhat cooler than today. Temperatures will be in the lower to middle 80s and then the upper 70s and lower 80s during the coming weekend. Nevertheless, the current predominantly warmer than normal pattern will likely persist through much of September, paving the way for a solidly warmer than normal summer and a warm start to fall throughout the region. Occasional short-lived cool shots remain possible. The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -0.6°C for the week centered around August 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.15°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions will likely develop. The SOI was -8.56. Today, the preliminary Arctic Oscillation (AO) figure was -0.627. On August 11, the MJO was in Phase 5 at an amplitude of 0.425 (RMM). The August 10-adjusted amplitude was 0.793. Some of the guidance suggests that the MJO could be in Phase 8 in late August. The convergence of the MJO's passage through phase 8 and revived tropical cyclone activity could suggest the possibility of an East Coast threat during the August 20-September 10 period. Phases 8-1-2 have coincided with a cluster of East Coast landfalls. Belle (1976) and Gloria (1985) made landfall when the MJO was in Phase 8 at a low amplitude. Sandy (2012) and Fay (2020) made landfall when the MJO was in Phase 2. The MJO's recent passage through Phase 4 at an amplitude of 1.500 or above has been uncommon during the first half of August. During the 1981-2019 period only 1983 and 2019 saw the MJO move through Phase 4 with an amplitude of 1.500 or above during the first half of August. August 1983 had the longest such stretch. Both cases saw the second half of August average generally warmer than normal in the Middle Atlantic region. Both cases also featured a warmer than normal September. Last year, the MJO went through a very strong passage through Phase 1 during the closing days of May. About four weeks later, a warmer than normal pattern locked in and predominated through early autumn. This year, the MJO was in Phase 1 for 3 consecutive days with an amplitude of 1.500 or above during the June 1-3 period. Last year, the SOI fell to -42.04 on June 22 when the MJO was in Phase 6. This year, the SOI plunged below -46.68 on June 5, its lowest level in more than three years. The dramatic plunge in the SOI could be the proverbial spark that kicks off a sequence of events leading to the development of a sustained warmer than normal period. The cases that saw both the MJO and SOI thresholds satisfied generally saw 10-20 days where the temperature reached or exceeded 90° in New York City during the July 1-August 31 period. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Overall, the evolution of ENSO, along with the observed ongoing monthly warming (1.6°/decade in NYC and 1.5°/decade in the Northeast Region during September 1990-2019), favors a warmer than normal September. Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. 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 August. August will likely finish with a mean temperature near 77.0°.

LGA 1.32” in the past hour.

Over the past hour, the temperature crashed from a daily high of 93 degrees to 73 degrees in Philadelphia as a heavy thunderstorm moved in. 1.00” rain was recorded during for the hourly period ending at 2:54 pm.

12z guidance (RGEM, NAM, and HRRR) are in line with Walt Drag’s thinking.

Morning thoughts... Yesterday, LaGuardia Airport recorded a minimum temperature of 80 degrees. That was the 7th 80-degree or above minimum temperature this year, which ties the record set in 2002. A frontal boundary will be located just to the north and west of cities such as Newark and New York City. As a result temperatures will again rise into the upper 80s across the region. A few locations could reach 90 degrees. Along the frontal boundary, heavy thunderstorms could develop, especially this afternoon and evening. An area that runs from Washington, DC to Armonk could see locations receive excessive rainfall. The HREF ensemble mean highlights the rainfall risk for Philadelphia and Washington, DC. South and east of the front should see less rain. Parts of Long Island may see little or no rain this afternoon and evening.

The temperature rose mainly into the upper 80s across the region today. Tomorrow should be a similar day. The current predominantly warmer than normal pattern will likely persist through much of September, paving the way for a solidly warmer than normal summer and a warm start to fall throughout the region. Occasional short-lived cool shots remain possible. The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -0.6°C for the week centered around August 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.15°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions will likely develop. The SOI was +8.44. Today, the preliminary Arctic Oscillation (AO) figure was -0.627. On August 10, the MJO was in Phase 5 at an amplitude of 0.796 (RMM). The August 9-adjusted amplitude was 1.259. Some of the guidance suggests that the MJO could be in Phase 8 in late August. The convergence of the MJO's passage through phase 8 and revived tropical cyclone activity could suggest the possibility of an East Coast threat during the August 20-September 10 period. Phases 8-1-2 have coincided with a cluster of East Coast landfalls. Belle (1976) and Gloria (1985) made landfall when the MJO was in Phase 8 at a low amplitude. Sandy (2012) and Fay (2020) made landfall when the MJO was in Phase 2. The MJO's recent passage through Phase 4 at an amplitude of 1.500 or above has been uncommon during the first half of August. During the 1981-2019 period only 1983 and 2019 saw the MJO move through Phase 4 with an amplitude of 1.500 or above during the first half of August. August 1983 had the longest such stretch. Both cases saw the second half of August average generally warmer than normal in the Middle Atlantic region. Both cases also featured a warmer than normal September. Last year, the MJO went through a very strong passage through Phase 1 during the closing days of May. About four weeks later, a warmer than normal pattern locked in and predominated through early autumn. This year, the MJO was in Phase 1 for 3 consecutive days with an amplitude of 1.500 or above during the June 1-3 period. Last year, the SOI fell to -42.04 on June 22 when the MJO was in Phase 6. This year, the SOI plunged below -46.68 on June 5, its lowest level in more than three years. The dramatic plunge in the SOI could be the proverbial spark that kicks off a sequence of events leading to the development of a sustained warmer than normal period. The cases that saw both the MJO and SOI thresholds satisfied generally saw 10-20 days where the temperature reached or exceeded 90° in New York City during the July 1-August 31 period. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Overall, the evolution of ENSO, along with the observed ongoing monthly warming (1.6°/decade in NYC and 1.5°/decade in the Northeast Region during September 1990-2019), favors a warmer than normal September. Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. Based on sensitivity analysis applied to the latest guidance, there is an implied 66% probability that New York City will have a warmer than normal August. August will likely finish with a mean temperature near 77.0°.

Morning thoughts... Overnight, the low temperature at LaGuardia Airport was 80 degrees. If that winds up as the daily low, that would be the record-tying 7th 80-degree minimum temperature. The record was set in 2002. Currently, 2020 is tied with 2006 and 2010 for second place with 6 such days. Across the region, today will again see temperatures rise mainly into the upper 80s and lower 90s. With fairly high humidity, the heat index will very likely exceed 100 degrees in many parts of the region.

The pattern has favored greater warmth to the north. For example, Burlington has had more 90 degree days than Central Park this year and it has the 4th highest figure on record. Caribou has its second highest such figure on record.

Scranton has had 22 such days this year vs. 12 last year. Mount Pocono has had none so far this year and none last year.

Under abundant sunshine, the temperature topped out in the upper 80s and lower to middle 90s across the region. High temperatures included: Baltimore: 93° Boston: 94° Burlington: 90° Harrisburg: 93° Islip: 89° New York City-JFK: 87° New York City-LGA: 95° New York City-NYC: 92° Newark: 94° Philadelphia: 92° Washington, DC: 92° 90° Days for Select Cities (through August 10): Albany: 13 (2019: 12 days) Allentown: 21 (2019: 24 days) Baltimore: 38 (2019: 59 days) Boston: 12 (2019: 15 days) Burlington: 19 (2019: 8 days) Harrisburg: 27 (2019: 33 days) Islip: 6 (2019: 8 days) New York City-JFK: 10 (2019: 7 days) New York City-LGA: 29 (2019: 26 days) New York City-NYC: 17 (2019: 15 days) Newark: 26 (2019: 28 days) Philadelphia: 30 (2019: 35 days) Washington, DC: 39 (2019: 62 days) New York City-Newark Average: 21 (2019: 19 days) ...Expected: 21 (based on regression equation tied to JFK-LGA-EWR data) Very warm temperatures with highs in the upper 80s and lower 90s are likely for tomorrow. The current predominantly warmer than normal pattern will likely persist through much of September, paving the way for a solidly warmer than normal summer and a warm start to fall throughout the region. Occasional short-lived cool shots remain possible. The ENSO Region 1+2 anomaly was -1.2°C and the Region 3.4 anomaly was -0.6°C for the week centered around August 5. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.15°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions could develop. Since 1950, there have been five cases where a La Niña developed during June-July-August or afterward following an El Niño winter. 4/5 (80%) of those cases saw a predominant EPO+/AO+ winter pattern. The most recent such case was 2016-17. 9/10 (90%) of the La Niña winters that followed an El Niño winter featured a predominantly positive EPO. The SOI was +13.47. On August 6, the SOI was +25.73. That was the highest figure since October 14, 2018 when the SOI was +27.20. In all three August cases where the August ENSO Region 1+2 anomaly was -0.75°C or colder, a La Niña winter followed. The most recent such case was August 2010. Today, the preliminary Arctic Oscillation (AO) figure was -0.182. On August 9, the MJO was in Phase 5 at an amplitude of 1.261 (RMM). The August 8-adjusted amplitude was 1.625. The MJO's passage through Phase 4 at such a high amplitude is uncommon during the first half of August. During the 1981-2019 period only 1983 and 2019 saw the MJO move through Phase 4 with an amplitude of 1.500 or above during the first half of August. August 1983 had the longest such stretch. Both cases saw the second half of August average generally warmer than normal in the Middle Atlantic region. Both cases also featured a warmer than normal September. Last year, the MJO went through a very strong passage through Phase 1 during the closing days of May. About four weeks later, a warmer than normal pattern locked in and predominated through early autumn. This year, the MJO was in Phase 1 for 3 consecutive days with an amplitude of 1.500 or above during the June 1-3 period. Last year, the SOI fell to -42.04 on June 22 when the MJO was in Phase 6. This year, the SOI plunged below -46.68 on June 5, its lowest level in more than three years. The dramatic plunge in the SOI could be the proverbial spark that kicks off a sequence of events leading to the development of a sustained warmer than normal period. The cases that saw both the MJO and SOI thresholds satisfied generally saw 10-20 days where the temperature reached or exceeded 90° in New York City during the July 1-August 31 period. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Overall, the evolution of ENSO, along with the observed ongoing monthly warming (1.6°/decade in NYC and 1.5°/decade in the Northeast Region during September 1990-2019), favors a warmer than normal September. Based on sensitivity analysis applied to the latest guidance, there is an implied 66% probability that New York City will have a warmer than normal August. August will likely finish with a mean temperature near 77.0°.

Researchers have narrowed the range of climate sensitivity from a doubling of atmospheric CO2. Unfortunately, all of the narrowing occurred at the bottom end of the range. As a result, the range was changed from 1.5C - 4.5C to 2.3C - 4.5C. The full paper can be found here: https://climateextremes.org.au/wp-content/uploads/2020/07/WCRP_ECS_Final_manuscript_2019RG000678R_FINAL_200720.pdf

Tuesday will likely be a little cooler, but readings could still approach or reach 90. I want to see additional guidance before having confidence in the possible weekend storm.

Morning thoughts... At 9 am, temperatures in the region included: New York City-JFK: 80° New York City-LGA: 83° New York City-NYC: 79° Newark: 80° Philadelphia: 78° High temperatures should reach the upper 80s to lower 90s across the region. Estimates for the above cities based on the latest guidance: New York City-JFK: 86° New York City-LGA: 93° New York City-NYC: 90° Newark: 92° Philadelphia: 91° Finally, for the second consecutive weekly period, the ENSO Region 3.4 anomaly was at -0.5°C or below (-0.6°C). The probability of the development of a La Niña ahead of the upcoming winter has continued to increase. Such events following El Niño winters have featured a predominently positive EPO.

Unfortunately, none of the wind reports distinguish between tornadic and straight line winds. The waterspout off of Cape May was listed as an EF1 tornado with 100 mph winds. I didn't see any confirmed storm reports for an EF3. Perhaps there was earlier speculation that the Cape May waterspout was an EF3 tornado.

Very warm temperatures with highs in the upper 80s and lower 90s are likely for tomorrow and Tuesday. The current predominantly warmer than normal pattern will likely persist through much of September, paving the way for a solidly warmer than normal summer and a warm start to fall throughout the region. Occasional short-lived cool shots remain possible. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.8°C for the week centered around July 29. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -1.08°C and the ENSO Region 3.4 anomaly has averaged -0.25°C. Neutral-cool conditions will likely into the start of autumn. During the autumn, La Niña conditions could develop. The SOI was +8.92. On August 6, the SOI was +25.73. That was the highest figure since October 14, 2018 when the SOI was +27.20. In all three August cases where the August ENSO Region 1+2 anomaly was -0.75°C or colder, a La Niña winter followed. The most recent such case was August 2010. Today, the preliminary Arctic Oscillation (AO) figure was +-0.028. On August 8, the MJO was in Phase 5 at an amplitude of 1.626 (RMM). The August 7-adjusted amplitude was 1.976. The MJO's passage through Phase 4 at such a high amplitude is uncommon during the first half of August. During the 1981-2019 period only 1983 and 2019 saw the MJO move through Phase 4 with an amplitude of 1.500 or above during the first half of August. August 1983 had the longest such stretch. Both cases saw the second half of August average generally warmer than normal in the Middle Atlantic region. Both cases also featured a warmer than normal September. Last year, the MJO went through a very strong passage through Phase 1 during the closing days of May. About four weeks later, a warmer than normal pattern locked in and predominated through early autumn. This year, the MJO was in Phase 1 for 3 consecutive days with an amplitude of 1.500 or above during the June 1-3 period. Last year, the SOI fell to -42.04 on June 22 when the MJO was in Phase 6. This year, the SOI plunged below -46.68 on June 5, its lowest level in more than three years. The dramatic plunge in the SOI could be the proverbial spark that kicks off a sequence of events leading to the development of a sustained warmer than normal period. The cases that saw both the MJO and SOI thresholds satisfied generally saw 10-20 days where the temperature reached or exceeded 90° in New York City during the July 1-August 31 period. Since 1990, there have been 11 La Niña events, 6 of which followed an El Niño winter. 10/11 (91%) case saw warmer than normal September. All 6 following an El Niño winter were warmer than normal. September mean temperatures for New York City for those cases were: 11 cases: 69.9°; Subset of 6 cases: 70.8°; Entire 1990-2019 period: 69.0°. The September mean temperature for all La Niña and neutral-cool cases following an El Niño winter (1950-2019: n=13) was 69.9°. Overall, the evolution of ENSO, along with the observed ongoing monthly warming (1.6°/decade in NYC and 1.5°/decade in the Northeast Region during September 1990-2019), favors a warmer than normal September. Based on sensitivity analysis applied to the latest guidance, there is an implied 68% probability that New York City will have a warmer than normal August. August will likely finish with a mean temperature near 77.2°.

Anniversary of the 1723 Hurricane: On this date in 1723, a possible hurricane made landfall in the Middle Atlantic region. The storm brought high winds and heavy rain to such cities as Philadelphia and New York, neither of which appeared to have had any memory of a hurricane. Weather conditions deteriorated rapidly during the mid-morning. In both cities, the wind started from the northeast but then veered to the southeast. The winds diminished during the latter part of the afternoon as the storm pushed away from the region. The Boston News-Letter wrote of the storm's impact on Philadelphia: ...there was a violent northeast storm of wind and rain, the wind shifting till about noon, and then blew very hard at southeast, which caused a great disorder among the shipping, and blew down several chimneys, a great many trees, and it did very much damage to fruit, the tide being very high a wharf was wash'd away, and damage was done to several other. That same newspaper reported the following account from New York: We are likewise inform'd from New York, that they had the like storm, at the same time, which broke up the wharffs from one end of the city to the other, drove all the vessels ashore, except three and broke three sloops to pieces; the tide higher than ever was known here, sugar and goods in warehouses and cellars, were damaged; the market house with several others were blown down, tyles & covering of houses blown off. Vast quantities of boards, timber, staves, boats, canoes and rubbish lies in heaps. The American Weekly Mercury reported the following account of the storm in New York: Yesterday about 8 or 9 a clock the wind came up here at northeast, and veered about more to the southeast and from 12 a clock till 4 it blew very hard, with rain, insomuch that it has broke up all the wharfs from one end of the city to the other, drove all the vessels (except three) onshore, and three sloops are broke all to pieces: the water came up into the city higher than ever was known before and has done abundance of damage to sugar and other goods in merchants cellars, the market house before the coffee house is blown down and several other houses, and the tyles and coverings of many houses were blown off. And if the storm had continued till the next high water, all the houses by the waterside would have been destroyed. All the wharfs round the great dock is drove away. And in the slips there is such vast quantities of boards, timber, staves, boats, canoes and other rubbish lies in heaps in such manner as was never seen here before. The pyrate sloop which Capt. Solgard brought in, was forced to cut her mast and is drove away.

I agree. For now, I take no position on the coming winter. I do have some concerns based on some of the long-range guidance heading into the fall.

FWIW, the EPS seasonal idea has temperature anomalies across North America that are similar to those of winter 1998-99. Fortunately, at least right now, that’s far in the future and a lot can change.