Chris Ewing Explains What Caused the Ice Storm of ’98 

The ice storm of 1998 was due in part to the strong El Nino that was present at that time. During El Nino winters the Sub-Tropical Jet Stream tends to be stronger than usual and that helps to keep the southern tier of the United States wetter than normal. The polar jet on the other hand typically remains north of its usual winter location and that tends to keep the pure arctic air trapped north of the U.S. Canadian border. On occasion during this type of pattern the Sub-Tropical Jet will turn north and allow the deep moisture laden airmass to move up the Eastern Seaboard as was the case in January of 1998. The ice storm started on January 5th and continued right through the 9th. On about the 5th a storm in the upper levels of the atmosphere began to develop over the Southern Plains States and this along with an unseasonably strong high over the Central Atlantic helped pull the Sub-Tropical Jet Stream up through the Ohio River Valley and then into Northern New England. At the same time the jet was pulling tropical moisture northward aloft a large and very slow moving surface ridge of high pressure was developing over South Central Quebec. The high at the surface turn the winds near the ground into the north and northeast and that caused the shallow arctic air over Quebec to ooze south into Northern New England. From January 5th through January 9th the cold front that introduced the arctic air at the surface to Maine stalled along the Southern New England Coastline. Over the same 5 days the high over Quebec expanded east into the Canadian Maritimes allowing arctic air to remain trapped at the surface across most of the Pine Tree State. Beginning on the 5th a series of storms developed over the Ohio River Valley and then rode northeast along the now stationary front located south of Maine. The storms were able to tap the tropical moisture associated with the Sub-Tropical Jet and draw it north into Maine. While temps near the ground remained below freezing the temps a few thousand feet up were warmer and that caused the snow falling aloft to melt as it moved through the warm layer a few thousand feet above the ground. As the precipitation moved back into the colder air near the surface it either turned into sleet or remained super cooled rain and then froze upon contact with any surface it touched. Far northern parts of Maine remained cold enough at all levels of the atmosphere that most of the precipitation fell as snow, while extreme southern and at times coastal parts of the state saw a combination of rain and freezing rain. The first couple of storms that slid by to our south brought light precipitation to our region on the 5th and 6th, with a much stronger storm arriving on the 7th and lasting into the 9th which brought heavier precipitation to our region . A cold airmass followed the storm beginning on the 10th as the last storm slipped offshore ant that ensured the ice would remain encased on all exposed surfaces for a prolonged period of time. When all was said and done about 2 to 5″ of freezing rain and sleet had accumulated all across Eastern and Central Maine.