Laurentian Great Lakes ice and weather conditions for the 1998 El Nino winter

Winter 1997/98 occurred during one of the strongest warm El Nino events, an d the Great Lakes experienced one of the least extensive ice covers of this century. Seasonal maximum ice cover for the combined area of the Great Lak es was the lowest on record (15%) relative to winters since 1963, a distinc tion formerly held by winter 1982/83 (25%), which was also an exceptionally strong El Nino winter. Maximum ice covers set new lows in winter 1997/98 f or Lakes Erie (5%), Ontario (6%), and Superior (11%), tied the all-time low for Lake Huron (29%), and came close to tying the all-time low on Lake Mic higan (15%; all-time low is 13%). Here the authors compare seasonal progres sion of lake-averaged ice cover for winter 1982/83, winter 1997/98, and a 2 0-winter normal (1960-79) derived from the NOAA Great Lakes Ice Atlas and d iscuss the 1997/98 ice cover in detail. Winter air temperatures in the Grea t Lakes were at or near record high levels, storms were displaced farther t o the south over eastern North America, and precipitation was below average in the northern portion of the Great Lakes region. The Northern Hemispheri c synoptic flow patterns responsible for this winter weather, the Great Lak es winter severity over the past two centuries, and impacts of this mild wi nter are briefly discussed.