bluewave

Yeah, I have been saying this for a while now. Once past the spring predictability barrier, the models like the Euro do a great job with ENSO SST plumes forecast. So the record breaking nature of this event isn’t in doubt. We can see the strong coupling with the atmospheric patterns in the tropics and the very high shear in the Caribbean. But the subtropics or mid-latitudes continue to do their own thing. It’s a very strong -PDO pattern north of the tropics rights now. If this mid-latitude pattern can continue to have some influence going into the winter, then the Aleutian low could split or end up in a different location than usual. It’s also possible the typical strong Nino ridge south of Hudson Bay could at least at times get displaced further to the south over the Eastern CONUS. This could mean that the heavily precipitation zones with the STJ may vary from the 1997-1998 locations like we saw in 2015-2016 and 2023-2024.

This is another example of how the models past 15 days really don’t have much skill other than general forecasts for ENSO SST plumes. Notice the locations of the ridges and troughs verifying are reversed from the seasonal forecast issued in May. Most of the time during the 2020s summers the long range models miss the strong -PDO and +AMO influence of these greatly expanded subtropical or mid-latitude ridges. July forecast issued in May Verification so far

In the old days with super El Niños, the strong low level westerlies would extend north from the tropics into the mid-latitudes like in 1997. During the 2020s, the subtropical or mid-latitude ridges have grown to record levels. So the westerly flow is much weaker with the high pressure dominating. The warm pool from Japan to north of Hawaii is allowed to continue leading to the persistent -PDO. This prevents the strong +PDO response that was typical in 1997 and 2015. This is also why we have see strong to record heat domes across the CONUS since May from time to time instead of the cooler typical El Niño pattern this time of year.

All-time record highs with this developing record 600 dm ridge. The 850 mb plume is forecast to set all-time warmest 850mb temperatures from Ontario into the Northeast. But the models have the 850 mb temperatures peaking at night. So they actually begin coming down a bit during Wednesday afternoon. The Euro and GFS both have 100°-103° at the warmest spots across the region Wednesday. RECORD EVENT REPORT NATIONAL WEATHER SERVICE BILLINGS MT 506 PM MDT SUN JUL 12 2026 ...RECORD HIGH TEMPERATURES ACROSS THE REGION TODAY... HERE IS A SUMMARY OF DAILY RECORDS AND ALL-TIME RECORDS TIED OR BROKEN SO FAR TODAY, SUNDAY, JULY 12TH. DAILY RECORDS BROKEN SITE HIGH TEMP PREVIOUS RECORD PERIOD OF RECORD BEGINS BILLINGS 111 107 (2002) 1934 LIVINGSTON 105 103 (2002) 1948 MILES CITY 115 104 (1954) 1937 SHERIDAN 109 104 (2002) 1907 BAKER 110 103 (2006) 1998 ALL-TIME RECORDS TIED OR BROKEN SITE HIGH TEMP PREVIOUS ALL-TIME RECORD PERIOD OF RECORD BEGINS BILLINGS 111 108 (7/14/2002) 1934 LIVINGSTON 105 105 (8/5/1961) 1948 MILES CITY 115 111 (6/26/2012) 1937 SHERIDAN 109 107 (7/27/2021) 1907 BAKER 110 109 (7/25/2024) 1998 AN UPDATED SUMMARY OF DAILY AND ALL-TIME RECORDS WILL BE SENT AT THE END OF THE DAY IF NEEDED.

I realize that and was talking more generally about the DJF means. 1997-1998 had the strongest connection between the Aleutian low and the low across the Southern Tier of the CONUS. There is always going to be variability from month to month and season to season between different super El Ninos. By 2015-2016 the Aleutian low was weaker along with the low in the Southeast even with the strong +PDO. 2023-2024 also had a weaker Aleutian low that split into two pieces. So the low across the Southeast was weaker than 1997-1998 also in the means. It’s also possible that the warming climate leading stronger and more extensive ridges and weaker troughs is playing a role also. The chart below shows the rising 500mb heights over North America and the adjacent oceans during DJF.

Yeah, 1997-1998 was the last canonical super El Niño. The La Niña-like influence in December 2015 merging with the Nino standing wave was through the MJO 5. The precipitation impacts were also different from previous super El Niños. In 2023-2024 we saw another MJO excursion through the IO and MC during January when the Southeast ridge emerged. The pattern since May has seen the strongest heat and ridging across the CONUS outside a neutral or La Niña summer with a strong -PDO influence. The summer -PDO drop and +AMO increase has been a common feature during the 2020s. So there are multiple ways for competing or overlapping marine heatwaves to interact with an El Niño. This summer is the most extreme example of a dominant -PDO pattern across the CONUS at the same time a record super El Niño is strengthening. The 2015-2016 and 2023-2024 super El Niños showed that the interaction actually resulted in warmer winters conditions than 1997-1998. Both winters featured the El Niño ridge south of Hudson Bay building down further into the Eastern U.S. than normal. But even if this event found a way to have the canonical 1997-1998 response, a +3.9 event alone without any -PDO or MC forcing influence could easily surpass 1997-1998 in spots for warmth. Ridges have been getting stronger than troughs regardless of whether we have an El Niño or La Niña.

Newark came closest in July 1966 reaching 100°. So the number to watch will be 101°+. All the other years stayed under 100° in the following 15 days of 104°+. July 1949 made it back to 101° on the 28th which was 24 days after. 1966-07-03 105 75 90.0 12.6 0 25 0.00 0.0 0 1966-07-04 100 78 89.0 11.5 0 24 0.00 0.0 0 1966-07-05 87 74 80.5 2.8 0 16 0.00 0.0 0 1966-07-06 87 73 80.0 2.2 0 15 T 0.0 0 1966-07-07 93 76 84.5 6.6 0 20 T 0.0 0 1966-07-08 91 70 80.5 2.4 0 16 0.00 0.0 0 1966-07-09 89 67 78.0 -0.2 0 13 0.00 0.0 0 1966-07-10 93 70 81.5 3.3 0 17 0.00 0.0 0 1966-07-11 96 72 84.0 5.7 0 19 0.00 0.0 0 1966-07-12 98 72 85.0 6.6 0 20 0.00 0.0 0 1966-07-13 100 77 88.5 10.1 0 24 0.00 0.0 1949-07-04 105 74 89.5 12.0 0 25 0.08 0.0 0 1949-07-05 95 73 84.0 6.3 0 19 0.00 0.0 0 1949-07-06 83 68 75.5 -2.3 0 11 0.47 0.0 0 1949-07-07 81 64 72.5 -5.4 0 8 0.06 0.0 0 1949-07-08 81 65 73.0 -5.1 0 8 0.00 0.0 0 1949-07-09 81 61 71.0 -7.2 0 6 0.00 0.0 0 1949-07-10 76 64 70.0 -8.2 0 5 0.13 0.0 0 1949-07-11 86 67 76.5 -1.8 0 12 0.00 0.0 0 1949-07-12 81 69 75.0 -3.4 0 10 0.17 0.0 0 1949-07-13 85 69 77.0 -1.4 0 12 0.56 0.0 0 1949-07-14 91 67 79.0 0.5 0 14 0.00 0.0 0 1949-07-15 80 71 75.5 -3.0 0 11 0.22 0.0 0 1949-07-16 81 71 76.0 -2.5 0 11 0.00 0.0 0 1949-07-17 75 70 72.5 -6.0 0 8 1.17 0.0 0 1949-07-18 93 70 81.5 3.0 0 17 T 0.0 0 1949-07-19 94 72 83.0 4.5 0 18 T 0.0 0 1949-07-20 94 74 84.0 5.5 0 19 0.00 0.0 0 1949-07-21 94 77 85.5 7.0 0 21 T 0.0 0 1949-07-22 97 75 86.0 7.5 0 21 0.01 0.0 0 1949-07-23 90 71 80.5 2.1 0 16 0.00 0.0 0 1949-07-24 90 63 76.5 -1.9 0 12 0.00 0.0 0 1949-07-25 94 69 81.5 3.2 0 17 0.03 0.0 0 1949-07-26 88 71 79.5 1.2 0 15 0.00 0.0 0 1949-07-27 97 71 84.0 5.8 0 19 T 0.0 0 1949-07-28 101 75 88.0 9.8 0 23 T 0.0 0 1949-07-29 100 75 87.5 9.4 0 23 0.00 0.0 0 1949-07-30 101 75 88.0 9.9 0 23 0.05 0.0

This will be the first 101°+ potential less than 15 days after 104°+ during July and August.

Really extreme over the top heatwave with parts of the Rockies and Plains approaching all-time highs today. The record 600 DM ridge will become very compressed leading to the 850 mb heat plume tracking through the Upper Great Lakes and Ontario next few days. The heat should peak in our area on Wednesday. Both the Euro and GFS have 100°-103° highs at the warm spots around the region. 101°+ would be a first to follow so quickly after 104°-106° heat earlier in the month.

This July is the most extreme difference between a developing super El Niño and the midlatitude 500 mb and temperature pattern across the CONUS. The tropics are clearly in El Niño mode as we can see from the forcing and -SOI with very strong shear over the Caribbean. Notice how the strong -PDO ridge north of Hawaii leads to the classic July -PDO SST pattern. This is an impressive July -PDO response across the CONUS with the record heat and ridging from the Plains to the East Coast. Strong July -PDO composites July 1-10, 2026 500 mb pattern

No doubt a cold month for that region. Just not as cold as the DMI ECMWF data. The persistence of low pressure closer to the Pacific side of the Arctic is a function of the big summer dipole reversal since 2013. This weaker dipole is the main reason that the 2012 record low has held into the 2020s.

This is the actual ERA 5 temperature map which produced the climate record for June 2026. The Pacific Arctic area to the north of Alaska did have its coldest June since the 1940s as I mentioned in my first post. But you can see how the total area from 80N to 90N had zones closest to the warmest on record on the Atlantic side. So the actual rank of the high Arctic wasn’t the coldest on record. Since the totality of the Arctic north of 60N had the warmest June on record. Even the less reliable ECWMF only starts in 2002, so an apples to apples comparison to any year earlier than 2002 can’t be made. This is why we use Era 5 for comparison to times since the 1940s.

The shifted nature of the ridges further south than usual over the CONUS is probably related to the persistent marine heatwave and 500 mb pattern from Japan to north of Hawaii driving the -PDO and contributing to the +AMO. A recent study found that this process is operating independently from the El Nino. So this more La Nina background pattern is overlapping with the developing super El Nino. If this interaction continues into the winter, then the El Nino ridge axis normally south of Hudson Bay could be located further south than usual. We’ll just have to see how the pattern evolves moving into the winter. https://www.science.org/doi/10.1126/sciadv.adz4647 Marine heatwaves in the Northwestern Pacific (NWP) have become increasingly frequent and persistent, yet the mechanisms enabling their multiseasonal duration remain poorly understood. Through observational analyses and climate model experiments, we demonstrate that NWP marine heatwaves are primarily driven by a quasistationary wavenumber 5 circumglobal wave (CGW) pattern that operates independently of El Niño–Southern Oscillation. The CGW modulates surface heat fluxes during summer, triggering a self-reinforcing feedback loop where NWP warming intensifies the CGW pattern, amplifying and prolonging heatwaves across extended warm seasons. Additionally, CGW-driven summer warming in the northern North Atlantic persists into winter through oceanic thermal inertia, exciting a great-circle wave pattern that propagates back to the NWP, sustaining heatwaves through cold seasons. This interplay between atmospheric waves and trans-basin interactions enables multiyear marine heatwave events. Analysis of observational data and climate model simulations reveals a strengthening CGW influence in recent decades, indicating more frequent and prolonged NWP marine heatwaves under ongoing global warming.

The forecast record breaking 600 DM ridge next week in the Upper Midwest is yet another pattern since May that doesn’t fit the typical developing record super El Niño playbook.

RECORD EVENT REPORT NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 0154 AM EDT FRI JUL 10 2026 ...RECORD DAILY MAXIMUM RAINFALL SET AT PHILADELPHIA PA... A RECORD RAINFALL OF 2.70 INCHES WAS SET AT PHILADELPHIA PA TODAY. THIS BREAKS THE OLD DAILY RECORD OF 1.79 INCHES SET IN 1952. THIS IS ALSO THE FIRST DAILY PRECIPITATION VALUE GREATER THAN 2 INCHES FOR PHILADELPHIA IN 837 DAYS, WHICH ENDS THE 4TH LONGEST SUCH STREAK ON RECORD. PRECIPITATION RECORDS FOR THE PHILADELPHIA PA AREA DATE BACK TO NOVEMBER 1871.