donsutherland1

Tomorrow and Wednesday will feature somewhat cooler weather in the Middle Atlantic and southern New England regions. However, heat will begin to build later in the week and during the weekend. Parts of the Southwest saw more scorching heat today. High temperatures included: Del Rio, TX: 112° (old record: 106°, 1998) ***Tied all-time record set on June 9, 1988*** Phoenix: 114° (tied record set in 1989 and tied in 2003 and 2005) With a high temperature of 91°, Washington, DC registered its 17th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 22-August 8, 1999 when the temperature reached 90° or above on 18 consecutive days. The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 8. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.72°C and the ENSO Region 3.4 anomaly has averaged -0.25°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below. The SOI was +1.85. Today, the preliminary Arctic Oscillation (AO) figure was -0.846. On July 12, the MJO was in Phase 2 at an amplitude of 1.884 (RMM). The July 11-adjusted amplitude was 1.961. The MJO has been in either Phase 1 or Phase 2 for 43 consecutive days. 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. Based on sensitivity analysis applied to the latest guidance, there is an implied 77% probability that New York City will have a warmer than normal July. July will likely finish with a mean temperature near 79.3°. Finally, on July 12, Arctic sea ice extent (JAXA) was 7.448 million square kilometers. That is the lowest figure on record for July 12. The previous record was 7.693 million square kilometers in 2011.

Temperatures rose into the 80s in the northern Middle Atlantic region and at or above 90° or above from Newark southward. Overnight, parts of the region will see showers and some thundershowers. Tomorrow will be somewhat cooler than today. In parts of the Southwest, record heat prevailed. High temperatures included: Palm Springs: 121° (old record: 120°, 1958 and 1985) Phoenix: 116° (old record: 115°, 2005 and 2009) Tucson: 113° (old record: 110°, 2005) With a high temperature of 90°, Washington, DC registered its 17th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 22-August 8, 1999 when the temperature reached 90° or above on 18 consecutive days. The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 1. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below. The SOI was +16.74. Today, the preliminary Arctic Oscillation (AO) figure was -0.959. On July 11, the MJO was in Phase 2 at an amplitude of 1.967 (RMM). The July 10-adjusted amplitude was 2.297. The MJO has been in either Phase 1 or Phase 2 for 42 consecutive days. 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. Based on sensitivity analysis applied to the latest guidance, there is an implied 75% probability that New York City will have a warmer than normal July. July will likely finish with a mean temperature near 79.3°.

The last thing I want to see is another winter like the last one.

Yes. It was predominantly negative last summer.

This evening, a thundershower moved through parts of southern Westchester County with a brief downpour and a gusty breeze. Afterward, a rainbow appeared over the Long Island Sound. Two photos:

In the wake of Tropical Storm Fay, sunshine returned to the region. Parts of the area saw one or more thundershowers. Tomorrow will be sunny and warmer with many parts of the region approaching or reaching 90°. With a high temperature of 93°, Washington, DC registered its 16th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 18-August 2, 2011 when the temperature also reached 90° or above on 16 consecutive days. The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 1. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below. The SOI was +13.11. Today, the preliminary Arctic Oscillation (AO) figure was -0.976. On July 10, the MJO was in Phase 1 at an amplitude of 2.300 (RMM). The July 9-adjusted amplitude was 2.513. That was the 21st consecutive day the MJO was in Phase 1. That broke the old record of 19 consecutive days in Phase 1, which was set during the July 6-24, 2004 period. In addition, the MJO has been in either Phase 1 or Phase 2 for 41 consecutive days. 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. Based on sensitivity analysis applied to the latest guidance, there is an implied 75% probability that New York City will have a warmer than normal July. July will likely finish with a mean temperature near 79.3°.

Yes. That’s why we may need to wait for the final reporting.

2.71” at MPO. Bridgeport reported a 49 mph gust. I suspect that there were probably a few 50 mph gusts on the South Shore of Long Island, but one might not know for sure unless there is an updated PNS or when the NHC issues it’s end-of-season report.

The passage of Tropical Storm Fay brought a swath of 2”-4” rain with some locally higher amounts. Some totals: Allentown: 1.92” Atlantic City: 3.24” New York City: ...JFK: 2.33” (old daily record: 0.86”, 1969) ...LGA: 2.45” ...NYC: 2.54” (old daily record: 1.94”, 1874) Newark: 2.78” (old daily record: 1.96”, 1950) Philadelphia: 4.15” (old daily record: 2.99”, 1931) Wilmington, DE: 2.76” (old daily record: 1.95”, 1917)

Overnight, Fay will continue to move northward in New York State and then into New England. Sunshine will return tomorrow with noticeably warmer temperatures. With a high temperature of 91°, Washington, DC registered its 15th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 18-August 2, 2011 when the temperature reached 90° or above on 16 consecutive days. The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 1. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below. The SOI was +21.85. Today, the preliminary Arctic Oscillation (AO) figure was -0.909. On July 9, the MJO was in Phase 1 at an amplitude of 2.522 (RMM). The July 8-adjusted amplitude was 2.598. That was the 20th consecutive day the MJO was in Phase 1. That broke the old record of 19 consecutive days in Phase 1, which was set during the July 6-24, 2004 period. In addition, the MJO has been in either Phase 1 or Phase 2 for 40 consecutive days. 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. Based on sensitivity analysis applied to the latest guidance, there is an implied 77% probability that New York City will have a warmer than normal July. July will likely finish with a mean temperature near 79.3°.

Four photos from Tropical Storm Fay from late this afternoon:

Two video clips from Tropical Storm Fay:

Thanks for the kind words.

This morning, there was a freshening northeast wind along the Long Island Sound. An area of fog rolled through the area. Two photos:

Tomorrow into Saturday, the region will be impacted by Tropical Storm Fay as it moves northward and passes near New York City into New England. Parts of Long Island and the south shore of Connecticut could experience an area of sustained winds near 50 mph. The region will likely see periods of heavy rain and thunderstorms. A swath of 2"-4" rainfall amounts with some locally higher figures is likely. The last time New York City received 1.00" or more rain in a single day was April 13, 2020 when 1.96" fell. The last time New York City picked up 2.00" or more daily rainfall was August 11, 2018 when 2.90" fell. The last time a storm brought 3.00" or more rain to New York City was April 15-16, 2018 when 3.29" was recorded. With a high temperature of 91°, Washington, DC registered its 14th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 18-August 2, 2011 when the temperature reached 90° or above on 16 consecutive days. The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 1. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below. The SOI was +12.37. Today, the preliminary Arctic Oscillation (AO) figure was -0.694. On July 8, the MJO was in Phase 1 at an amplitude of 2.601 (RMM). The July 7-adjusted amplitude was 2.647. That was the 19th consecutive day the MJO was in Phase 1. That tied the record of 19 consecutive days in Phase 1, which was set during the July 6-24, 2004 period. In addition, the MJO has been in either Phase 1 or Phase 2 for 39 consecutive days. 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. 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 July. July will likely finish with a mean temperature near 79.2°.

A lot will depend on the duration and magnitude of the heat that develops next week. 80 will be a stretch, but it is possible.

Tomorrow will be steamy with readings near or above 90° in a large part of the region. Late in the week into the weekend, parts of the region could be impacted by tropical moisture. At that time, the region could see some rounds of heavy rain and thunderstorms. The potential for a swath of 2"-4" rainfall amounts with some locally higher figures exists. The guidance remains in disagreement over the location where the heaviest rain will fall. With a high temperature of 92°, Washington, DC registered its 13th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 21-August 2, 2016 when the temperature also reached 90° or above on 13 consecutive days. The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible Initially, extreme heat is unlikely, but that could change as July progresses, especially if the emerging drought continues to deepen. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 1. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below. The SOI was +1.66. Today, the preliminary Arctic Oscillation (AO) figure was -0.359. On July 7, the MJO was in Phase 1 at an amplitude of 2.650 (RMM). That was the fourth highest amplitude in July when the MJO was in Phase 1. The July 6-adjusted amplitude was 2.605. That was the 18th consecutive day the MJO was in Phase 1. The last time the MJO had at least as long a stretch in Phase 1 occurred during September 21-October 8, 2019 when the MJO was also in Phase 1 for 18 consecutive days. In addition, the MJO has been in either Phase 1 or Phase 2 for 38 consecutive days. 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. 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 July. July will likely finish with a mean temperature near 79.0°.

Under partly to mostly cloudy skies, temperatures rose only into the 80s across much of the region. Parts of Long Island and the Connecticut shore remained in the 70s. Tomorrow will likely be somewhat warmer. Late in the week, parts of the region could be impacted by some tropical moisture. At that time parts of the area could see some rounds of heavy rain and thunderstorms. With a high temperature of 90°, Washington, DC registered its 12th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 11-22, 2019 when the temperature also reached 90° or above on 12 consecutive days. The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible Initially, extreme heat is unlikely, but that could change as July progresses, especially if the emerging drought continues to deepen. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 1. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below. The SOI was -3.08. Today, the preliminary Arctic Oscillation (AO) figure was -0.084. On July 6, the MJO was in Phase 1 at an amplitude of 2.607 (RMM). That was the fourth highest amplitude on record for July when the MJO was in Phase 1. The July 5-adjusted amplitude was 2.496. That was the 17th consecutive day the MJO was in Phase 1. The last time the MJO had a longer stretch in Phase 1 occurred during September 21-October 8, 2019 when the MJO was in Phase 1 for 18 consecutive days. In addition, the MJO has been in either Phase 1 or Phase 2 for 37 consecutive days. 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. Based on sensitivity analysis applied to the latest guidance, there is an implied 69% probability that New York City will have a warmer than normal July. July will likely finish with a mean temperature near 79.0°.

Under bright sunshine ahead of an advancing backdoor cold front, the temperature soared into the lower and middle 90s in many parts of the region. Central Park reported a high temperature of 96°. That was New York City's highest temperature since July 1, 2018 when the temperature also reached 96°. During the evening strong thunderstorms, some of which produced small hail, moved through parts of the region. Philadelphia had a 92° high temperature, marking its 5th consecutive 90° or warmer day. With a high temperature of 96°, Washington, DC registered its 11th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 11-22, 2019 when the temperature reached 90° or above on 12 consecutive days. The current predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible Initially, extreme heat is unlikely, but that could change as July progresses, especially if the emerging drought continues to deepen. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -1.1°C and the Region 3.4 anomaly was -0.1°C for the week centered around July 1. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.65°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The last time the six-week moving average for ENSO Region 1+2 was as cold as the current figure during July or August occurred in 2013. Winter 2013-14 had neutral-cool ENSO conditions. January and February featured ENSO Region 3.4 anomalies that were -0.50°C or below. The SOI was +3.38. Today, the preliminary Arctic Oscillation (AO) figure was +0.062. On July 5, the MJO was in Phase 1 at an amplitude of 2.493 (RMM). The July 4-adjusted amplitude was 2.237. That was the 16th consecutive day the MJO was in Phase 1. The last time the MJO had a longer stretch in Phase 1 occurred during September 21-October 8, 2019 when the MJO was in Phase 1 for 18 consecutive days. In addition, the MJO has been in either Phase 1 or Phase 2 for 36 consecutive days. 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.

At 9 am, the temperature in Central Park was 84 degrees. The 0z GFS MOS showed a high of 86 degrees and the 6z GFS MOS showed a high of 85 degrees. Today will likely see the temperature approach or exceed 90 degrees in Central Park. As has become fairly common over the past few weeks, perhaps on account of the continuing rainfall deficit, the MOS will fall at least several degrees short of the actual high temperature.

Under bright sunshine, much of the region saw temperatures top out in the 90s in much of the region. Tomorrow will likely feature similar temperatures. Philadelphia had a 95° high temperature, marking its 4th consecutive 90° or warmer day. With a high temperature of 93°, Washington, DC registered its 10th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 11-22, 2019 when the temperature reached 90° or above on 12 consecutive days. Number of 90° Days for Select Cities (through July 5): Albany: 8 (2019: 12) Allentown: 6 (2019: 24) Baltimore: 14 (2019: 59) Boston: 1 (2019: 15) Burlington: 10 (2019: 8) Harrisburg: 7 (2019: 33) Islip: 0 (2019: 8) New York City: 5 (2019: 15) Newark: 8 (2019: 27) Philadelphia: 9 (2019: 35) Washington, DC: 14 (2019: 62) Excessive heat will likely build over the Central Plains this week. Some of that heat will then try to expand eastward. The potential for the season's first heat wave in New York City remains a possibility starting later this week. However, the probability of that outcome has declined in some of the more recent guidance. The predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible Initially, extreme heat is unlikely, but that could change as July progresses, especially if the emerging drought continues to deepen. One or more heatwaves are likely in July across the region, including New York City. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was +0.1°C for the week centered around June 24. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.48°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The SOI was -0.62. Today, the preliminary Arctic Oscillation (AO) figure was -0.188. On July 4, the MJO was in Phase 1 at an amplitude of 2.223 (RMM). The July 3-adjusted amplitude was 1.631. That was the 15th consecutive day the MJO was in Phase 1. The last time the MJO had a longer stretch in Phase 1 occurred during September 21-October 8, 2019 when the MJO was in Phase 1 for 18 consecutive days. In addition, the MJO has been in either Phase 1 or Phase 2 for 35 consecutive days. 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. Finally, on July 4, Arctic sea ice extent (JAXA) was 8.507 million square kilometers. That was the lowest figure on record for July 4. The old record was 8.598 million square kilometers, which was set in 2016.

Somewhat cooler air moved into the region overnight. Farther south in the Middle Atlantic region, temperatures again returned to the 90s. Philadelphia had a 92° high temperature, marking its 3rd consecutive 90° or warmer day. With a high temperature of 94°, Washington, DC registered its 9th consecutive day on which the temperature reached 90° or above. That is Washington's longest heat wave since July 11-22, 2019 when the temperature reached 90° or above on 12 consecutive days. The modest respite from the heat will be short-lived. Excessive heat will likely build over the Central Plains next week. Some of that heat will then expand eastward. The potential for the season's first heat wave in New York City is on the table for later next week. Philadelphia will very likely experience a continuation of its current heat wave. There, temperatures could rise into the middle or even upper 90s on one or two days. The predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible Initially, extreme heat is unlikely, but that could change as July progresses, especially if the emerging drought continues to deepen. One or more heatwaves are likely in July across the region. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was +0.1°C for the week centered around June 24. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.48°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The SOI was -4.93. Today, the preliminary Arctic Oscillation (AO) figure was -0.342. On July 3, the MJO was in Phase 1 at an amplitude of 1.627 (RMM). The July 2-adjusted amplitude was 1.331. That was the 14th consecutive day the MJO was in Phase 1. The last time the MJO had a longer stretch in Phase 1 occurred during September 21-October 8, 2019 when the MJO was in Phase 1 for 18 consecutive days. In addition, the MJO has been in either Phase 1 or Phase 2 for 34 consecutive days. 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.

From earlier today:

Ahead of a backdoor cold front that produced scattered thunderstorms this evening, temperatures surged to 90° or above from New York City and southward. High temperatures included: Allentown: 92° Baltimore: 96° Bridgeport: 87° Harrisburg: 97° Hartford: 87° Islip: 88° New York City: 90° Newark: 93° Philadelphia: 97° Washington, DC: 97° Somewhat cooler air will return for the July 4 weekend. The modest respite from the heat will be short-lived. Excessive heat will likely build over the Central Plains next week. Some of that heat will then expand eastward. The potential for the season's first heat wave in New York City is on the table for later next week. A predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible Initially, extreme heat is unlikely, but that could change as July progresses, especially if the emerging drought continues to deepen. One or more heatwaves are likely in July across the region. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was +0.1°C for the week centered around June 24. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.48°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The SOI was +11.02. Today, the preliminary Arctic Oscillation (AO) figure was -0.331. On July 2, the MJO was in Phase 1 at an amplitude of 1.331 (RMM). The July 1-adjusted amplitude was 1.254. That was the 13th consecutive day the MJO was in Phase 1. The last time the MJO had a longer stretch in Phase 1 occurred during September 21-October 8, 2019 when the MJO was in Phase 1 for 18 consecutive days. In addition, the MJO has been in either Phase 1 or Phase 2 for 33 consecutive days. 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.

Today was the warmest day of the season so far in parts of the region. High temperatures included: Albany: 93° Baltimore: 91° Bridgeport: 87° Islip: 87° New York City: 92° Newark: 95° Philadelphia: 93° Washington, DC: 92° Somewhat cooler air will return for the July 4 weekend. As a result, parts of the area could see thundershowers tomorrow, some of which could be strong. However, the modest respite from the heat will be short-lived. Excessive heat will likely build over the Central Plains next week. Some of that heat will then expand eastward. The potential for the season's first heat wave in New York City is on the table. A predominantly warmer than normal pattern will likely persist through at least August, paving the way for a solidly warmer than normal summer throughout the region. Occasional short-lived cool shots remain possible Initially, extreme heat is unlikely, but that could change as July progresses, especially if the emerging drought continues to deepen. One or more heatwaves are likely in July across the region. The ENSO Region 1+2 anomaly was -0.8°C and the Region 3.4 anomaly was +0.1°C for the week centered around June 24. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.48°C and the ENSO Region 3.4 anomaly has averaged -0.37°C. Neutral-cool conditions will likely prevail through mid-summer. The probability of the development of a La Niña event during late summer or early autumn has increased in recent weeks. The SOI was +14.77. Today, the preliminary Arctic Oscillation (AO) figure was -0.221. On July 1, the MJO was in Phase 1 at an amplitude of 1.253 (RMM). The June 30-adjusted amplitude was 1.309. 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. Just as had been the case last year, July and August could feature warm anomalies in the East. July-August 2019 saw 13 days on which the temperature reached or exceeded 90° in New York City.