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.

Required is a review of the upper air patterns from the 2014-16 “warm blob” years for the PNA region during APR/MAY and JUN/JUL to help time maximum snowmelt/water runoff in key Southwest Canada HYDRO locations. The 2026 “warm blob” has record strength aerial coverage making the 2014-16 “warm blob" years a reasonable analog.