The Nino34 SSTA is exactly normal (again) as meteorological summer arrives in the northern hemisphere. The APR/MAY 2025 multivariate ENSO index (MEI) was steady at -0.4. While oceanic ENSO is exactly neutral, atmospheric ENSO is borderline La Nina. In the subsurface, there is no change in the upper ocean heat anomalies which are slightly warm during recent weeks. A collection of operational Nino34 SSTA forecasts reveal a tendency toward weak La Nina for later this year.

-GLAAM has been common since the middle of last February. -GLAAM is present when mid-latitude jet stream flow is slower than normal increasing the risk of longwave trough presence and attendant storminess. Interestingly, the persistent -GLAAM produced widespread wet soil moisture changes around the northern hemisphere during meteorological spring.

The just-issued ECMWF “monthlies” aggressively forecasts consistent anomalous dry and hot climate across the central and northern Great Plains and much of the Canadian Prairies for July through September. The model shifts wet weather risk to the East Coast and Gulf of Mexico Coast leaving high pressure across the North-central States. The high-pressure location is also inspired by a tendency for monsoon thunderstorm activity across the Southwest U.S.  

The ocean surface off the Northeast Corridor Coast has cooled significantly during the past 2 weeks. Much of the cooling is due to a countering (to the Gulf Stream) cold current flowing southwestward from just off Newfoundland. The ocean surface is several to 6C cooler than normal in this cool zone, most vividly indicated off the northern Mid-Atlantic Coast.