The state of La Nina has not changed all that much this week. The SSTA has stabilized to support a basin-wide weak La Nina state. Meanwhile, the SOI values also have stabilized to support weak La Nina conditions, with daily contributions showing a strong positive signal over the past seven days. The monthly values are around 8, and the seasonal values are around 14.
The one interesting change is in the subsurface, where temperature anomalies have fallen again. The coldest anomalies are found under NINO 3.4, with some signs of the colder water lifting into the surface around NINO 3.4 and 4 or around 170 W to 140 W longitude. This observation would support the current forecast from IRI/CPC and the CFS model suites of keeping La Nina in place through at least September, possibly even through October, followed by a weakening to a neutral state by November and December.
The influences of La Nina will remain in place with a strengthening Polar jet stream expected in the Fall to battle with a robust western Atlantic ridge. This pattern configuration is expected through August and September and should shift towards a deep trough over the Eastern United States in October.
