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.

The Ohio Valley eastward to Pennsylvania is within a significant level of severe weather risk for later today and tonight. HRRR projects strongest radar returns between 7-8PM EDT specifically for North-central Illinois and Indiana to Northern Ohio toward Pittsburgh, PA. In this stretch and slightly southward is the greatest risk of tornadoes. By late evening, the squall line is slightly less intense although aerial coverage broadens through the northern Mid-Atlantic States to southern New England.