Forecast models are in good agreement on a cold spike striking the Northeast U.S. Thursday night/Friday morning and lasting through next weekend. The peak of cold is Friday morning through Saturday morning when very cold temperatures are accompanied by high wind producing extreme wind chill.

Today’s afternoon “European Model” indicated an evolving storm late Sunday night/early Monday centered on Missouri shifting toward West Virginia Monday evening and offshore the northern Mid-Atlantic States Tuesday morning. A wide range of weather is produced by this storm.

Rather than using any single model the mega-cluster ensemble which accounts for all models projects "most likely" scenarios which are more reliable. The most recent mega-cluster ensemble projection of temperature anomalies for the northern hemisphere in the extended-range (days 11-15) indicates steady presence of the winter 2020-21 arctic air reservoir stretched across Russia.

The multivariate ENSO index (MEI) for NOV/DEC 2020 was -1.2. This value represents moderate intensity La Nina. The MEI is an excellent ENSO diagnostic as the index measures the reaction of the atmosphere to the cooling waters of the equatorial East Pacific. During the mature phase of La Nina, typically occurring in DEC/JAN for La Nina events since the middle 1990’s a mature phase La Nina MEI of <-1.0 was typically followed by sustained La Nina whereas MEI >-1.0 were more likely to produce La Nina dissipation and possibly El Nino later in the year.