CLEVELAND - I'm watching the computer forecasts carefully as February approaches. As expected, December and January have been dominated by cold weather patterns in the North Atlantic. Its called the North Atlantic Oscillation, or NAO. A strongly negative NAO favors bitter cold air dropping down into the Great Lakes and Eastern States. That's exactly what's happened so far.
The jet stream is the belt of strong winds aloft, at about 18,000 feet, that steer and guide all major surface storm systems westward across the U.S. Thanks to a strongly negative NAO this winter, the jet stream has dipped far southward through the Mississippi Valley all the way toward the Gulf Coast. It then has curve back north and eastward along the Atlantic Coast toward the Canadian Maritimes. The current storm track has placed the battle ground for surface storms along the East Coast of the USA. In fact, several major winter storms, or Nor'easters, have run up the Atlantic Coast, dumping heavy rain and snow across the major East Coast cities.
But the negative NAO signature is weakening now and expected to remain weaker through the month of February. So, what now?
Its tough to ignore one of the strongest La Nina events since the 1950s currently churning in the equatorial Pacific Ocean. La Nina is the cooling of the Pacific Ocean near the equator. La Nina tends to shift winter storms back into the Ohio Valley and the Great Lakes, giving Northern Ohio a shot at periodic heavy rains and heavy snows through the cold weather months.
With a weakening NAO, and a still-strong La Nina, I would expect a shift toward a La Nina weather pattern for the Eastern US beginning sometime in February. If this happens, and the jet stream shifts the storm track back into the Ohio Valley in February, then low pressure systems would travel northeast across, or near our state with more frequency. That would mean nastier weather for the North Coast. For example, if the center of a winter storm would travel from Texas across Western Ohio, Toledo, & Detroit, then Northeast Ohio would be poised for a brief, but pronounced warm-up with heavy rainfall. If the winter storm center stays farther south and moves along the Ohio River toward Pittsburgh, then get ready for some heavy snowfall. We call this a "Panhandle Hook." Its a storm that has historically delivered our areas' heaviest snowfalls.
Of course, Old man Winter could still change his mind and keep the arctic air pouring in for the rest of winter. That would continue our current pattern of less snow and more bitter cold. I will continue to watch and wait for the pattern shift. Until then, you've been warned: expect Ohio's weather to become a lot more active in February and March...