Cold, windy start to May: What to expect in coming weeks

COLUMBUS, Ohio (WCMH) -- Much to the chagrin of all of us hoping that spring is finally around the corner, the jet stream is diving far to the south for the third week in a row, ushering in a March-like pattern of wind, chilly air and periodic showers. There could even be some mixed graupel in the northern counties.

The reason is a developing "Omega block" pattern in the jet stream, resembling the Greek letter, that forces cold air far to the south over the eastern half of the country. Low pressure will swirl over the eastern Great Lakes, digging southward.

High temperatures on Monday could set low records in a few Ohio cities, with readings stuck in the lower 40s.

April ran warm early and cool late in central Ohio, with above-average precipitation that included a few storms that produced large hail.

Warm weather came early this spring, with a maximum reading of 84 degrees in Columbus on Apr. 20. However, after several mild weeks, a chilly pattern with patchy frost settled in.

Indications are that May will likely play out in the reverse of April: A very chilly beginning, then a seasonably warm finish. The average high temperature in early May is in the upper 60s in central Ohio, which will eventually rise to the upper 70s by Memorial Day.

NOAA's Climate Prediction Center is projecting slightly above-average temperatures and near- to below-normal precipitation for the majority of the month in the upper Ohio Valley region.

The wettest areas will probably be the Southeastern states, which would reflect a continuation of the late April southern storm track.

The demise of La Niña -- cooler-than-average sea surface temperatures in the central and eastern Pacific -- will help reshuffle the deck regarding the overall circulation, possibly replaced by El Niñ0 by early autumn, which has a different climatological pattern (wetter southern U.S. in fall/winter, drier north).