bluewave

Officially the coolest start to August since 2013 which was a nice break from the wall to wall heat since late June. Hoping the 0z Euro has a clue about the more onshore flow and the 100° heat misses to the north in Maine. But the GFS still has more westerly flow and gets the warm spots to 101° on Wednesday. We are one of the parts of the country where a small shift to more southerly flow can make the difference between 90s and low 100s. Time Series Summary for NEWARK LIBERTY INTL AP, NJ August 1-7 Average Temperature Click column heading to sort ascending, click again to sort descending. 2025-08-07 74.5 1 2024-08-07 81.7 0 2023-08-07 75.6 0 2022-08-07 83.1 0 2021-08-07 75.6 0 2020-08-07 78.7 0 2019-08-07 77.9 0 2018-08-07 82.2 0 2017-08-07 74.9 0 2016-08-07 75.8 0 2015-08-07 79.1 0 2014-08-07 75.9 0 2013-08-07 73.2 0 2012-08-07 80.4 0 2011-08-07 80.6 0 2010-08-07 79.9 0

The 0z Euro backed off the 100° heat and has more onshore flow. But the GFS still has 101° heat on Wednesday. With the late July heatwave, the Euro had a cool bias and missed a few of the 100s that verified. Would be nice if this 0z Euro had a clue and the 100° heat misses to our north in Maine.

Maybe we can disrupt this dry heat pattern a bit after the 17th if the EPS is correct about the tropics becoming more active near the East Coast. But that is still a pretty far ways off to know if the model is correct. Plus we keep seeing the heat reload into the longer range all summer even when the models have forecast a relaxation. But in the old days we could often count on the tropics to break these heatwaves extending into mid-August. Just not sure if this will be the case yet. But it’s worth monitoring. August 18-25

The tendency has been more +PNA in July since 2013 with a strong 500 mb ridge in the East. Prior to this recent decade we usually had more of a -PNA when there was a strong ridge in the East. Have also been seeing more ridging in the East during the winters in the 2020s with + PNAs than we used to in the past.

Really extreme shift following the very wet pattern during the summer of 2023 and historic flooding last August from CT to LI with 10-15” in a short time on the 18th. https://www.climate.gov/news-features/event-tracker/extreme-rainfall-brings-catastrophic-flooding-northeast-august-2024

Yeah, locations that didn’t have the flooding have been very dry this summer. My area just east of HVN has had the 11th driest June 1st through August 6th. Most of the grassy areas are brown around here. It has also been the 2nd warmest summer over the same period. Very uneven rainfall patterns across the area during recent years. Last few years have been an all or nothing type of rainfall patterns. Where we alternate between drought and flash flooding. Light rains don’t do much in such a warm climate since the warmth quickly dries things out after the light rains. A cooler summer can do OK with less rainfall. Time Series Summary for NEW HAVEN TWEED AP, CT Driest June 1st through August 8th Click column heading to sort ascending, click again to sort descending. 1 2000-08-06 1.80 60 2 1957-08-06 2.70 0 3 2017-08-06 3.01 3 4 1966-08-06 3.16 0 5 2016-08-06 3.44 0 6 2014-08-06 3.46 1 7 1954-08-06 3.49 0 8 1976-08-06 3.76 0 9 1949-08-06 3.86 0 10 2022-08-06 3.88 0 11 2025-08-06 4.15 0 Time Series Summary for NEW HAVEN TWEED AP, CT Warmest June 1st through August 8th Click column heading to sort ascending, click again to sort descending. 1 2024-08-06 76.1 0 2 2025-08-06 75.1 0 3 1977-08-06 74.9 31 4 2022-08-06 74.5 0 - 2020-08-06 74.5 2 5 2010-08-06 74.4 0 6 2019-08-06 74.0 0 7 2013-08-06 73.9 0 8 2012-08-06 73.5 0 - 2008-08-06 73.5 0 9 2023-08-06 73.1 1 10 2011-08-06 72.9 0

Dry conditions expanded heading into the heatwave next week. https://droughtmonitor.unl.edu/CurrentMap/StateDroughtMonitor.aspx?Northeast Northeast Drought Summary Very warm weather with persistently below normal precipitation for the past few weeks has allowed short-term moisture deficits to develop in a number of locations. Conditions have been the most anomalous across northern New England and far Upstate New York, where several areas of abnormal dryness (D0) were introduced. D0 was also brought in to parts of the immediate southern New England coast. A small area in southeastern New Hampshire and adjacent Massachusetts saw D0 conditions eradicated after 1 to 2.5 inches of rain fell this past week, but robust precipitation was not common across areas of existing dryness. Short-term precipitation deficits were also emergent in parts of New Jersey and Pennsylvania, but no dryness designation seemed appropriate yet, although these areas will need to be monitored for deterioration in the next few weeks if precipitation doesn’t return to near normal.

Yeah, June and July 2009 were both very cool and wet summer months around the area. It was the 2nd coldest June-July period on record at LGA. Recent years have had numerous top 10 warmest. This June and July was +6.1° warmer at LGA than 2009 was. The same period back in 2020 was a full +8°warmer. Time Series Summary for LAGUARDIA AIRPORT, NY Top 10 Coolest June 1st through July 31st Click column heading to sort ascending, click again to sort descending. 1 1972-07-31 70.3 0 2 2009-07-31 71.4 0 3 1982-07-31 71.6 0 4 1978-07-31 71.9 0 5 1969-07-31 72.0 0 - 1947-07-31 72.0 0 6 1958-07-31 72.3 0 7 1940-07-31 72.5 0 8 1946-07-31 72.6 0 9 1985-07-31 72.7 0 - 1975-07-31 72.7 0 - 1950-07-31 72.7 0 10 2000-07-31 72.9 0 - 1974-07-31 72.9 0 Time Series Summary for LAGUARDIA AIRPORT, NY Top 10 Warmest June 1st through July 31st Click column heading to sort ascending, click again to sort descending. 1 2020-07-31 79.4 0 - 2010-07-31 79.4 0 2 1994-07-31 78.1 0 3 1999-07-31 78.0 0 4 2024-07-31 77.9 0 - 2008-07-31 77.9 0 5 2013-07-31 77.7 0 6 2025-07-31 77.5 0 7 2016-07-31 77.4 0 - 1966-07-31 77.4 0 8 1952-07-31 77.3 0 9 2019-07-31 77.2 0 10 2006-07-31 77.1 0

Yeah, I enjoyed the really cool summers growing up in Long Beach that we would get every few years. That 2010 summer really reset our whole summer pattern to much warmer. 2009 was the last time we had a cool summer here. While 2014 was our last comfortable summer, it didn’t really make it to the 2009 level of coolness. 2009 was the last top 10 coolest June and July which was the coolest since the 1940s. As the recent less warm summers like 2023, 2017, and 2014 were a function of the much warmer summer climate normals. Those were still a little warmer than the long term average. Plus 2023 and 2017 still had between 15-20 days at places like JFK with a 75° or greater dew point. So those very high dew points worked against the cooler and lower humidity summers of the past.

July was the strongest Southeast ridge on record for the month from NYC to ATL. This beats the previous record July 500mb heights set back in 1952. But the difference this time is that we had a +0.74 PNA for July. While July 1952 had a -1.23 PNA. So we continue to see these disconnects between the higher latitudes and mid-latitudes. This disconnect is why the Euro still has a Southeast ridge into next winter while also having a -EPO and +PNA.

Right on cue the pace of Arctic sea ice loss has slowed behind the 2012 record drop experienced in early August 2012. That was at the end of an historic Arctic Dipole pattern from 2007-2012 leading to all the records over that 6 year period. This season so far has continued the much weaker Arctic Dipole pattern since 2013. So this changed summer Arctic circulation pattern since then has resulted in no sea ice trend since those steep declines. But the Arctic has seen increasing warmth over this period. So even with these more favorable conditions for Arctic sea ice retention, the sea ice thickness and extent has not returned to the pre 2007 state. Most Septembers finish between 4-5 million sq km over this period well below the major Arctic shift in 2007. I mentioned the melt pond data from early in the season which is one of the early indicators to look at. But this was the first year it hasn’t been published online. It probably would have shown something near the middle of the pack based on the lack of strong warmth this May. This was the opposite of the strong preconditioning in 2012 and 2020. 2012 was a perfect storm of a strong Arctic Dipole pattern following significant May preconditioning and the record Arctic cyclone in early August. These three features have not occurred in tandem since then. Special thanks to Gerontocrat from preparing the current extent which is in 7th place and 593K higher than 2012 as of August 9th. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2024GL114546

The story of this summer and much of the last decade has been the models underestimating the WAR or SE Ridge beyond 5 days. So this has been a repeating model forecast error. Around August 1st the forecast for August 11-18 had a modest warm up into the 90s. Definately a rebound from the less warm pattern this week. But now much of the guidance brings back 100° potential again. So you can see this big shift in the models in just 5 days of runs. New run August 11-18 Old run

Looking like models want to bring back the 100° heat for spots like Newark next week before the 15th. Be interesting to see if this matches recent history since 1994 of no 100s after August 15th. But wouldn’t be surprised if we eventually end up getting late August into early September 100° heat again. Especially since the model runs over the last 5 days have really dried out the forecast pattern again after the locally flooding rains last week. Not a great precedent to set for this much warmer climate if we can continue to reload 100° heat following these flash flood events. Past instances of these flooding events usually came after the 100s and we didn’t get follow up 100s. I was thinking as recently as a few days ago that maybe only a few warm spots in NJ could challenge 100° again. But the latest guidance is suggesting that 100° heat could also be possible in places like Queens. So unfortunately we may be entering an even warmer phase of these already warmer to record warm summers since 2010. The posters that were suggesting that we could see a mid-August heatwave at least rivaling the one back in late July may turn out to be correct. Good call on your part.

2009 was the last time that we had both a cool September and October.

Very impressive storm for this time of year with such a strong +NAO vortex.

Yeah, unfortunately that storm track inland from the East Coast has become a persistent feature since 18-19. Plus we have seen some version of a highly amplified North Pacific ridge most years since 16-17. Some years the ridge axis lines up more with the Aleutians and other years it’s closer to the West Coast. Either way we never miss an opportunity for the Southeast ridge to overperform especially near storm time.

Pretty funny. But the Euro has never shown a +5 anomaly in the Northeast from a seasonal forecast issued in the summer or fall. While we have had numerous warm anomalies near that magnitude since 15-16. If seasonal models can get at least one or two elements correct with a seasonal forecast, then we should be happy. I think the JMA back in October 2013 was the last time one of these seasonal models really hit it out of the park.

I think the last time the Euro seasonal had reasonably good winter forecast from October was 21-22. The forecast from August 21 was a miss. During the October forecast it got the idea of the -PNA correct for December. But the magnitude of the warmth and -PNA depth was way underdone. Probably related to the inability to correctly model the MJO beyond 1-2 weeks out. Then the January forecast was a miss since the MJO 8 wasn’t forecast beyond the late December period. February was reasonably close. Plus the 3 month mean blended together was OK. It wasn’t a mismatch type winter so it didn’t throw the seasonal off like we got last October which we were discussing last year. So probably just wait until we see how the October MJO indicator works out and what the model shows at that point.

The Euro seasonal is going with a delayed start to fall which has become common in recent years.

Just wondering were the seasonal model error will actually be during the winter since we seldom see perfect forecasts from any of the models from this range.

If something resembling that pattern verifies, then elevation and higher latitude will be your friend in the Northeast like we have seen during recent seasons.

I am just commenting on what the model is showing. It’s striking how similar it is to the 500mb pattern we are getting this summer. If we do get a pattern resembling that next winter, then maybe the worst in terms of those strong -PNAs like we had in 21-22 and 22-23 is behind us. But it looks like the model still wants to go with the storm track through the Great Lakes which has been persistent since 18-19.

The Euro has an active storm track through the Great Lakes for the crew in the favored lake effect snow zones.

Yeah, very similar. It goes to the comments I made earlier. There is a disconnect between the higher latitude teleconnections and the mid-latitude pattern. So we still get the subtropical ridge from the Pacific across the U.S. and Atlantic even with the -EPO +PNA.

The Euro has the same winter pattern at 500mb as we are getting this summer. It’s a -EPO +PNA and Southeast Ridge pattern. Pattern persistence or the model is in repeater mode? Stay tuned….