bluewave

The lack of 90° heat this May in the past for the warm spots like Newark has resulted in summers which haven’t exceeded 40 days going over 90°. So this early spring signal would suggest that top tier years for 90° days like 2010 and 2022 when Newark approached 50 days reaching 90° won’t occur this summer. So we are probably in for more onshore flow again this summer with areas west of NYC seeing the strongest heat and cooling sea breezes further east. The only year in the past to reach 40 days with no 90° temperatures at Newark in May was 1983. But that was a much different super El Niño pattern. It was also in the more westerly flow era. These days we have been seeing more summer onshore flow with the elongated ridge to the north and east of New England. All years with no 90° heat at Newark in May Annual and Monthly Number of Days Max Temperature >= 90 for NEWARK LIBERTY INTL AP, NJ following no 90° days in May Click column heading to sort ascending, click again to sort descending. 2025 0 0 M M M M M 0 2020 0 0 5 17 9 0 0 31 2014 0 0 2 8 2 3 0 15 2009 3 0 0 1 10 0 0 14 2008 0 0 6 11 2 3 0 22 2005 0 0 10 11 12 4 0 37 2003 0 0 5 8 7 0 0 20 1997 0 0 7 10 3 0 0 20 1990 2 0 5 9 9 1 0 26 1989 0 0 4 12 8 3 0 27 1984 0 0 8 6 8 0 0 22 1983 0 0 7 15 11 7 0 40 1982 0 0 1 10 1 0 0 12 1976 2 0 7 2 4 0 0 15 1973 0 0 5 9 12 5 0 31 1972 0 0 0 16 4 1 0 21 1971 0 0 6 7 7 2 0 22 1968 0 0 4 9 9 1 0 23 1967 0 0 5 1 1 0 0 7 1966 0 0 10 14 8 1 0 33 1963 0 0 6 11 3 0 0 20 1961 0 0 4 13 8 9 0 34 1960 1 0 3 2 8 1 0 15 1958 0 0 2 11 6 2 0 21 1954 0 0 5 10 3 0 0 18 1952 0 0 8 17 2 4 0 31 1950 0 0 8 6 3 1 0 18 1946 0 0 5 5 2 0 0 12 1940 0 0 2 11 1 1 0 15 1938 0 0 4 4 9 0 1 18 1935 0 0 1 11 2 0 0 14 Years at Newark with 40-50 days reaching 90° with multiple days over 90° in May Monthly Number of Days Max Temperature >= 90 for NEWARK LIBERTY INTL AP, NJ from April to October Click column heading to sort ascending, click again to sort descending. 2010 1 2 13 21 11 6 0 54 2022 0 4 6 20 18 1 0 49 1993 0 3 9 22 11 4 0 49 1988 0 1 10 15 17 0 0 43 2021 0 4 12 11 13 1 0 41 2002 4 1 5 16 14 1 0 41 1991 0 8 10 9 12 2 0 41 2016 0 3 3 16 13 5 0 40 1983 0 0 7 15 11 7 0 40 1959 0 5 5 8 15 6 1 40 Recent years with 50 days reaching 90° at Newark had demonstrated the major heat potential in May. This year Newark only made it to 88° in May. 2022 made it to 98° in May. 2010 reached 95° in May Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2025 87 88 M M M M M 88 April to October Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2022 88 98 96 102 101 93 76 102 April to October Monthly Highest Max Temperature for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 2010 92 95 98 103 98 98 79 103

The climate across the globe has significantly shifted from the mean state we were in back in 09-10. The base state was fairly stable from the late 1800s into the early 1980s. The first temperature jump out of this much colder era occurred in 82-83. So none of the winters which have occurred since then have been as cold as the late 1970s. We saw a much more significant rise in temperatures during 97-98. So we have not experienced a winter as cold as we saw from the mid 80s up to 1994. Plus this is when the all or nothing snowfall pattern began around NYC Metro after being stable from the early 60s to early 90s with many moderate snowfall seasons in the middle of the range. It’s also why the 95-96 snowfall season hasn’t been rivaled around NYC. The next significant rise in global temperatures occurred in 15-16. This is why we haven’t seen a repeat of winters like 09-10, 10-11, 13-14, and 14-15 since then. The planet has recently experienced a much greater rise in temperatures to a new higher baseline with the 23-24 winter. So this is why we were not able to see a repeat this past 24-25 winter of the 13-14 analog which was being discussed back in December. This new warmer base state was significantly higher than the 13-14 winter. The only way for the climate system to return to a colder baseline would be through major to historic volcanism. But unfortunately such an event in this modern world would be extremely disruptive. Absent any major volcanism, we will just keep shifting the baselines higher with every new periodic global temperature jump. So a whole series of winter analogs prior to 15-16 become out of reach for the new warmer baseline.

We can add May 2025 to the list for the 10.00+ amounts in the northern sections of the OKX forecast zones. Monthly Data for May 2025 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NJ WEST MILFORD TWP 2.5 SSE CoCoRaHS 12.73 CT PROSPECT 1.9 ENE CoCoRaHS 12.67 NY PORT JERVIS 2.9 ESE CoCoRaHS 11.47 NY NEW WINDSOR 3.3 W CoCoRaHS 10.98 CT PROSPECT 0.5 SW CoCoRaHS 10.79 NY WARWICK 3.2 WNW CoCoRaHS 10.54 NY WARWICK 3.9 W CoCoRaHS 10.25 NJ RINGWOOD 3.0 SSE CoCoRaHS 10.09

It would be very difficult in this much warmer climate for a 09-10 repeat during an El Niño. First, we get more Southeast Ridge link ups with the -NAOs during the 2020s. So New England wouldn’t have to worry about -NAO suppression and confluence like they had in 09-10. The STJ riding too far north would be more of a risk for mixed precipitation from Philly to Boston. Since a stronger Southeast Ridge or Western Atlantic Ridge would probably mean plenty of cold rain from DC to Philly. But I would still take my chances from around NYC Metro into Southern New England that at least one system would really connect for a major snowstorm.

While this doesn’t meet the formal definition, this has some sting jet-like features. Very strong W to NW winds next few hours behind the system with the steepening low level lapse rates. So some spots could gust past 50mph next several hours as models have been underestimating the wind gusts here this year.

The location of the upper low holds the key to our first 90°. If it gets out of the way like the 12z run today, then we’ll have our first 90° next week at the usual warm spots. More of a 0z solution then we’ll top out in the 80s. This is a pretty big jump in just one run. But models usually struggle with closed low solutions. 12z 0z

Yeah, this is why we were +5 a few weeks ago for May and now down to 0 to +2.

Still quite a bit of inshore flow with the cutoff low lingering nearby. The usual warm spots will probably get back to the 80s. But the first 90° still looks delayed to beyond the first week of June.

The record high pressure east of Japan in association with the record warmth has shifted the timing of the rainy season there.

NYC metro will approach the lowest late May pressures on record tomorrow. We will probably come in about 5mb above the all-time May and June lows. 987 mb is a record for May 31st and just above the monthly lows in the low 980s. So people will be looking at their home barometers and asking what month is this.

This looks like it will be the deepest low in the Northeast near the end of May since 2003. Models now have pressures dropping below 985mb. The last storm this strong at this time of year was a 981mb low on Cape Cod on June 1st 2003. https://www.wpc.ncep.noaa.gov/ncepreanal/

Yeah, the heat builds in CA and goes up into Canada. This time of year in 2023 was when we had the record air pollution from the Canadian wildfires. That had to be some if the worst air quality we ever saw.

The rapid expansion of the WPAC warm pool over the last decade becoming the most extreme since 2019 is largely the result of the record 500mb to surface ridging in that region leading to clear skies and light winds warming the SSTs below. The interesting thing is how deep below the surface the warming extends. While the 500mb pattern can shift for a few months leading slightly cooler SSTs, the SSTs rapidly rebound when the ridge returns like we have seen this spring following a brief winter hiatus. The challenge is that we are adding so much heat to the system evidenced by the record global temperature jumps in 15-16 and 23-25, that we don’t really understand why the WPAC has been warming more rapidly than the other parts of the Pacific. So it’s uncertain whether an extreme EPAC warming leading to an El Niño event event even bigger than 23-24 would even shift the STJ for more than a season before the Northern Stream of the Pacific Jet takes over again the next year. That’s why my comments were that I would just be grateful to see some semblance of a STJ and benchmark track pattern. Obviously a high end volcanic event could shift the pattern and storm track back colder for a period of time, but it would only be transient until the effects wear off and the warming resumes. Remarkable Changes in the Dominant Modes of North Pacific Sea Surface Temperature https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101078

We started seeing record heat and drought well north into Canada since around 2021. May 2023 was pretty extreme with the record 500mb blocking leading to the worst wild fires on record especially in Eastern Canada. So this current over the top warming is just a continuation of the same theme.

All this low pressure in the Northeast could continue to have a say. While it does look like we will see a warm up first week of June, the higher end heat potential may remain capped since models are now coming around to an upper low lingering nearby. So we probably see a return back to 80s. But not sure if the first 90s of the season will occur if there is too much onshore flow. Perhaps, the interior sections of NJ would have the best shot. This is looking like another over the top warm up. The most impressive temperature departures may go to our north again. Upper low lingering nearby first week of June

I know that people around here don’t like all the milder winters, but we may need a really strong El Niño like 15-16 to bring back at least some semblance of a STJ. Weak El Niños or warm neutrals such as 18-19 and 19-20 have been struggling against the La Niña background state. The primary driver has been the WPAC warm pool. Would much rather take my chances getting a very strong to super El Niño as long as the storm track is close to the benchmark. Really don’t care at this point if it’s near 60° before or after the storms or how long the snow stays on the ground. Just want to see some great snowstorms again. But as we saw in 23-24, the La Niña background combined with the very strong El Niño to pull the forcing too far west in the Pacific near the Maritime Continent. So really not sure if even a very strong El Niño can shift the marine heatwaves around which have been associated with the record WPAC warm pool. There is very little we can do from Philly to south coastal side Boston when the Northern Stream of the Pacific Jet is so strong. With Great Lakes cutters, I-95 to I-84 huggers, and suppressed Southern Stream storm tracks. The default position becomes milder winters with below to well below normal snowfall. Even the marginally colder winter this year was still around 40° near the coast on the days that .25 or more of precipitation fell. Perhaps, we can score a decent MJO 8 like we last saw in January 22 in the coming winters. Even one good month can make the winter passable. But we have seen in recent winters how we haven’t been able to get a clean MJO 8 response due to the competing marine heatwaves and multiple areas of forcing.

Very strong recent south based -NAO especially at 500mb warming the seas below with clear skies and strong high pressure. https://s2s.worldclimateservice.com/climatepanel/

Yeah, really comfortable temperatures for this time of year. These late May deep upper lows have been a regular feature here over the years. The Euro has been hinting at a usually strong phaser this weekend. Very rare to see a 984mb low in the Northeast at the end of May. The GFS just came on board for a deep Northeast low also and phasing between the two streams.

Very comfortable temperature pattern for this time of year continuing right into early June over the next 10 days. Very familiar over the top warmth into Canada. So the first 90° of the season is running late.

Yeah, this spring has featured the same very strong La Niña background 500mb pattern which has dominated since around 2019. Pretty much being driven by the WPAC warm pool and 500m ridge pattern. Notice how amplified the Aleutian Ridge has been along with the Southeast or Western Atlantic Ridge. We can also see the Aleutian Ridge continuing to extend back very close to Japan. This is the 2n EOF of the -PDO which has been at record levels since 2019. Spring 2025 similar to the pattern since 2019

Yeah, NYC was able to reach 106° back in 1936 when the weather equipment wasn’t underneath a dense stand of trees which grew up around and over the site. Our last series of summers without marine influence was back in 2010-2013. It’s when Newark to parts of Long Island reached 108° with strong westerly downsloping offshore flow. Now that the global background temperatures have jumped much higher than 2010 twice in 15-16 and 23-24, we have been getting onshore summer flow due to the ridge expanding more to the east of New England. While our summers have still been well above average temperatures with record dew points, drought feedback is necessary to set an all-time high in the warm season. All of our new monthly maximum temperatures have occurred in the winter and fall since 15-16. We set an all-time winter max of 80° in February 2018 which beat the previous record of 76° by 4°. The new all-time October high of 96° back in 2019 beat the old record by 3°. That inky took a brief flash drought which emerged in September. But nothing like the record droughts further back in the past. The most extreme summer heatwave in the CONUS since 2020 was in the Pacific Northwest back in 2021. Stations best their all-time summer high by 6°. So if our 108° summer heat back in 2010 was ever exceeded by 6°, then it would be 114°. But there isn’t any present indication in the new much wetter climate with more onshore flow that that type of scenario would be likely anytime soon here.

All our summer heat over the last decade had come with onshore flow and record high dew points. This is a result of the big ridge setting up east of New England. So the 100° heat has been mostly found over NJ with only occasional instances into Queens. It has also been a pretty rainy summer pattern. From 2010 to 2013 the ridge was to our west over the Great Lakes. So we got frequent westerly flow downsloping events. Even though the dry patterns were modest compared to earlier times, we still maxed out at 108°. Parts of the Pacific Northwest had highs 6° above the all-time levels back in 2021. The result of the much warmer climate in the 2020s and the historic droughts out West. So if this area ever saw a 1960s style drought with 2020s temperatures and westerly flow, then the max temperature potential would probably be 112° to 114°. The good news is that it’s very difficult to meet these conditions in this new climate. Since it’s uncertain how well our power grid would function with widespread temperatures that high.

Pretty wild how JFK has had the 7 lowest spring high temperature at only 82° while the average high temperature has been 3rd warmest. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Mar through May Click column heading to sort ascending, click again to sort descending warmest spring temperature 1 1983 75 0 - 1967 75 0 3 1968 78 0 - 1958 78 0 4 2008 79 0 - 1984 79 0 - 1966 79 0 5 2005 80 0 6 1961 81 0 - 1950 81 0 7 2025 82 7 - 2004 82 0 - 1997 82 0 - 1982 82 0 - 1972 82 0 - 1971 82 0 - 1951 82 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending average spring high temperature 1 2010 64.0 0 2 2012 63.1 0 3 2025 62.6 7 4 2024 62.5 6 - 1985 62.5 0 5 1991 61.8 0 6 1986 61.3 0

These late season upper cold pools are great if you like higher elevation snows.

New England has been very lucky since their last Hurricane Bob way back in 1991. This has been related to the 500 mb heights rising faster north and east of New England relative to the Gulf Coast. The last major U.S. hurricane major landfall north of Jacksonville occurred in 1996. This is a new record for the U.S. Coastline relative to the total U.S. major landfalling hurricanes over a 30 year period. It’s part of the reason that there have been so many high impact major landfalling hurricanes in and around the Gulf Coast recently. Even Sandy was driven west into SNJ near ACY and avoided a New England landfall. This is why it was so damaging around the NY Bight. https://www.aoml.noaa.gov/hrd/hurdat/All_U.S._Hurricanes.html