The Nino SSTA regions observed no change last week as neutral ENSO persists. The waters have warmed near the Dateline reaching the El Nino threshold while Nino34 remains neutral. Upper ocean heat in the equatorial East Pacific accelerated earlier this year and lowered slightly in early March. However, upper ocean heat east of the Dateline in the equatorial region has re-intensified and is strongly supportive of an El Nino event ahead.

The March upper ocean heat content in the equatorial Pacific Ocean continues to warm, the warmest since June 2023 during the last El Nino episode. The level of warmth rivals the approaching 2015 El Nino but is well short of the immense 1997 El Nino.

Climate Impact Company utilizes the ECM ENS and AIFS ENS for most medium-range temperature anomaly forecasts due to their consistent no. 1 and 2 skill score ranking. During the past 30 days, the temperature forecast bias for 15-day forecasts has generally been too warm for Canada and too cool for parts of the U.S. The ECM ENS bias is stronger than AIFS ENS.

The Madden Julian oscillation (MJO) is key to the forecast and indicates a transitional 2-week pattern, unable to establish a tropical connection to the U.S. precipitation pattern. However, the southern oscillation index (SOI) finally shifts to negative phase in April which indicates El Nino should organize and a wet bias in the southern latitudes acting as a moisture source for the Great Plains could generate.