Waters off the Northwest Coast of South America Observe Coolest Anomaly (-1.9) Since July 2013

Sharp Temperature Flip in Central South America Pattern Ahead
04/24/2022, 2:22 pm EDT
NOAA U.S. Drought Monitor Updated
04/28/2022, 9:11 am EDT
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Highlight: Waters off the northwest coast of South America observe coolest anomaly (-1.9) since July 2013. Meanwhile, Kelvin Wave is strengthening in central subsurface Pacific.

Fig. 1: The Nino12 SSTA is -1.9C for the past week and -1.94C for the day. The observation is the coolest on record since July 2013.

Discussion: A remarkable transition has taken place in the Nino12 SSTA region off the northwest coast of South America. The daily Nino12 SSTA is -1.94C (Fig. 1) and the weekly Nino12 SSTA is -1.9C (Fig. 2) which is the coolest since July 2013. While the Nino12 SSTA is super cool, note the anomalous warmth emerging right-along the South America coast near the equator. At a glance, La Nina is roaring back. HOWEVER, a warm subsurface Kelvin Wave has edged eastward about 120-180 miles during the past week and is now close to 155W longitude (Fig. 3). The Kelvin Wave is a little stronger compared to mid-April. At the surface, a robust easterly flow is spreading anomalous cool water westward while at 125-250-meter depth a counter-current is pushing subsurface warmth eastward. Forecast models biased toward the surface trend are re-instating La Nina for 2022. Ultimately, however, the subsurface regime decides this issue. So…a CAREFUL eye on the progress of the Kelvin Wave over the next few weeks is in order! Keep in mind, NOAA is the only government center forecasting La Nina for August 2022 while all other centers indicate neutral ENSO (Fig. 4).

Fig. 2: Weekly Nino SSTA regions for the past 12 weeks identifies the dramatic cooling in the Nino12 zone.

Fig. 3: The subsurface equatorial Pacific Ocean features a stronger Kelvin Wave pushing eastward to 155W during the past week.  

Fig. 4: Government centers ENSO phase forecasts for August 2022.