bluewave

Both the mid-latitude North and South Pacific ridges have dramatically expanded since the late 90s. The first expansion coincided with the first global higher baseline temperature jump following the 1997-1998 super El Niño. The 2nd and more dramatic expansion occurred following the 2015-2016 super El Niño. This is the pattern which is driving the record -PDO since 2018-2019 with the record surface and subsurface warm pool from Japan to north of Hawaii. Some of the climate models run back in 2013 were showing a similar pattern developing. But it was forecast to be a much slower process than what has occurred and be focused a little further north. So my guess is that the planet is much more sensitive to the effects of warming than the climate models forecasted. Plus the model which showed this ridge expansion also forecast to lower pressures over the Arctic the summer like we have seen since 2013. We were just discussing the very strong low north of Alaska during June. North Pacific 500 mb ridge expansion

Radar estimates close to 4 inches where the flash flooding occurred in Queens.

New all-time highest MSLP record set for Australia.

The main expansion mostly occurred following the 2015-2016 super El Niño with the big global temperature jump to a much higher baseline. It’s part of the reason that the ridges have been more impressive than the troughs as the planet warms regardless of the ENSO phase. The mid-latitude ridge growth has been driving the persistent -PDO/-AMO SST patterns. But there could be a feedback process at work between the ocean and atmosphere. We can notice the Aleutian low weakening since the 1980s with the super El Niños.

This was a great satellite loop from the other day that sums up what we have been experiencing this week.

Flash flood threat NYC metro with this warm frontal training first round of convection. Some hail also beginning to show up. Tropical PWATS with this. Mesoscale Precipitation Discussion 0766 NWS Weather Prediction Center College Park MD 1128 AM EDT Sat Jul 18 2026 Areas affected...portions of the coastal Mid-Atlantic Concerning...Heavy rainfall...Flash flooding possible Valid 181528Z - 182128Z Summary...A couple rounds of showers and thunderstorms with heavy rainfall are expected into late this afternoon. Hourly rain amounts to 2.5" are possible, which could lead to flash flooding in urban areas. Discussion...A thermal boundary extends through portions of the Mid-Atlantic States. Near the boundary, showers and thunderstorms are showing some slight backbuilding character while moving northeast into New York City. Precipitable water values are 1.4-2". MU CAPE is 500-5000 J/kg across the region, with the maximum on the Eastern Shore. Effective bulk shear is ~40 kts. One bout of heavy rainfall in the very near term is expected across southeast NY and portions of CT, while later development is expected to the southwest which should ride up the boundary back into the Tri-State area. Hourly rain amounts to 2.5" are possible either from backbuilding, cell training, or mesocyclone formation. This would be most problematic in urban areas.

Impressive severe and flash flooding threat. The AMO has rapidly increased to near record levels. So a deep tropical moisture feed with strong shear.

We began to dry out shortly after the super El Nino in 2023-2024 during the fall. The warmer climate requires more water than 50 years ago due to increased evaporation rates. One of the areas that needs more research are these expanding 500mb ridges that get stuck in place for weeks to months. So we get regions with record drought under the ridges which are bounded by record flooding like we are currently seeing in Texas. The more erratic precipitation patterns are a real challenge for the agricultural and landscaping fields. Since long range precipitation forecasts beyond a week or two aren’t the greatest. Trying to figure out where your local area will end up between the wet and dry extremes isn’t the easiest to navigate.

NYC needs to pick up 2.77” by the end of July to have their first average to above precipitation month since May 2025. https://forecast.weather.gov/product.php?site=NWS&issuedby=NYC&product=CLM&format=CI&version=1&glossary=1&highlight=off Monthly Total Precipitation for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 2026 2.70 2.60 3.60 2.48 3.05 3.39 1.83 M M M M M 19.65 2025 0.61 2.60 5.52 3.25 6.58 2.46 4.03 2.21 2.76 4.08 2.09 3.38 39.57 2024 5.28 2.05 9.06 3.47 4.11 1.71 4.20 7.02 1.58 0.01 3.35 4.53 46.37

The rapid expansion of the record heat and drought in Canada during the 2020s along with how remote the forests are makes this a very challenging issue with no quick fixes.

It probably helped that the Southeast had much colder winters back in that era.

Yeah, at least the 100°+ heat has really been front-loaded during the 2020s. Monthly Highest Max Temperature for HARRISON, NJ May-September Click column heading to sort ascending, click again to sort descending. Mean 92 98 101 97 91 101 2020 87 96 98 97 91 98 2021 93 101 100 99 90 101 2022 96 98 102 101 92 102 2023 89 93 97 92 96 97 2024 88 100 101 100 86 101 2025 88 103 102 95 90 103 2026 100 97 106 M M 106 Monthly Number of Days Max Temperature >= 100 for HARRISON, NJ May-September Click column heading to sort ascending, click again to sort descending. Mean 0 1 2 0 0 3 2020 0 0 0 0 0 0 2021 0 1 1 0 0 2 2022 0 0 3 1 0 4 2023 0 0 0 0 0 0 2024 0 1 1 1 0 3 2025 0 3 3 0 0 6 2026 1 0 3 M M 4

1997 -1998 would be a case of the warmest departures for NYC occurring in January and February. The actual February average temperature was the warmest monthly temperature of the winter. Dec…38.2°….+2.0 Jan…40.0°…..+8.6° Feb…..40.6°….+7.0° 2023-2024 had the warmest departure in December and the 2nd warmest in February. Dec…44.6°…..+5.5° Jan….37.0°……+3.3° Feb….40.1°……+4.2° 2015-2016 was the most extreme front-loaded super El Niño for warmth with +13.3 in December. Dec….50.8°…..+13.3° Jan…..34.5°….+1.9° Feb…..37.7°……+2.4°

Parts of the East had their lowest snowfall of the 1800s that winter. The big story during the 1877-1878 super El Niño was the warmth in the Upper Midwest. It’s an example how really strong El Niños can sometimes have their warmest departures in February. While we don’t have the 1841-1870 climate normals for MSP, I used the earliest available 30 year period. The departures for them that winter would have been like if December 2015 had run through February 2016 in the Northeast with no pattern reversal. MSP 1877-1878 DEC….+14.5 JAN…..+9.8 FEB……+15.8 Monthly Mean Avg Temperature for Minneapolis-St Paul Area, MN (ThreadEx) Click column heading to sort ascending, click again to sort descending. Mean 19.3 12.0 15.7 15.6 Max 33.8 1877 25.9 1880 31.9 1877 1872-1873 6.0 5.4 12.8 8.1 1873-1874 17.6 12.2 12.6 14.1 1874-1875 17.2 -3.4 -2.6 3.7 1875-1876 24.7 15.7 15.9 18.8 1876-1877 8.3 8.6 31.9 16.3 1877-1878 33.8 21.8 31.5 29.0 1878-1879 19.1 16.1 12.7 16.0 1879-1880 11.5 25.9 19.6 19.0 1880-1881 13.2 7.9 17.1 12.7 1881-1882 29.0 19.0 30.4 26.1 1882-1883 15.0 0.8 12.1 9.3 1883-1884 19.7 8.8 12.9 13.8 1884-1885 14.8 4.4 11.3 10.2 1885-1886 21.0 3.7 14.9 13.2 1886-1887 7.3 0.7 9.4 5.8 1887-1888 17.4 -0.4 13.1 10.0 1888-1889 25.2 20.7 10.6 18.8 1889-1890 28.8 10.6 19.2 19.5 1890-1891 24.4 21.6 11.8 19.3 1891-1892 30.1 13.5 22.9 22.2 1892-1893 16.8 7.3 12.0 12.0 1893-1894 14.0 12.3 15.7 14.0 1894-1895 28.1 7.0 12.0 15.7 1895-1896 22.5 16.8 22.3 20.5 1896-1897 24.4 10.6 20.0 18.3 1897-1898 15.3 23.0 20.6 19.6 1898-1899 14.1 13.7 7.8 11.9 1899-1900 21.4 21.3 8.6 17.1 1900-1901 21.0 15.2 12.3 16.2 1901-1902 15.9 18.7 18.2 17.6

The variability we have been getting into mid-July is more a function of the mid-latitude wave pattern doing its own thing relative to the tropics through mid-July with the strong -PDO +AMO summer 2020s background pattern. It’s a first for the developing super El Niño composite including 2023, 2015, 1997, 1982, and 1972. The current forcing from 150E to 30W is more impressive than both 2015 and 1997 combined. This doesn’t rule out intervals of IO to MC forcing into the winter. But it could be an early sign than the -PDO +AMO mid-latitude enhanced ridge pattern could overlap with the super El Niño composite going into the winter.