Subsurface East Pacific Cools Dramatically: La Nina Is On the Way!

Weak La Nina Likely During Tropical Cyclone Season
05/10/2020, 9:48 am EDT
Possible Early Season Tropical Cyclone Next Week
05/13/2020, 10:43 am EDT
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A leading indicator of ENSO phase change is a sudden change in the equatorial East Pacific subsurface temperature anomaly analysis. The latest analysis by NOAA/CPC indicates a DRAMATIC late April/early May cooling east of the Dateline. The risk of La Nina developing in AUG/SEP/OCT 2020 as indicated by several forecast models is well-supported by this cooler subsurface Pacific diagnostic.

Discussion: In late April/early May the NOAA/CPC analysis of the subsurface temperatures in the equatorial Pacific Ocean east of the Dateline cooled RAPIDLY. The sudden and rapid cooling trend STRONGLY supports forecast models indicating La Nina by late summer. In fact, if the trend which developed in early May continues a La Nina onset could occur before mid-summer. A La Nina episode occurring during the North Atlantic tropical cyclone season strongly enhances hurricane frequency and intensity. At the surface the Nino SSTA regions are (also) cooling from the borderline El Nino signature of the past few months to neutral ENSO the past couple weeks (Fig. 1). Additional cooling at the surface is likely possibly quickly in May!

Fig. 1: At the surface the Nino SSTA regions are cooling and in neutral phase now after many months of borderline weak El Nino.