COLUMBUS, Ohio (WCMH) — An unusually mild winter in Ohio and much of the Midwest and East will likely be followed by a warmer-than-average and periodically stormy spring, based on the newly released three-month outlook issued by NOAA’s Climate Prediction Center.
A waning La Niña that features cooler water in the tropical eastern Pacific has an 85%-95% chance of returning to neutral sea surface temperatures in the spring, according to NOAA.
La Niña is a climate pattern that influences the jet stream, forcing the steering winds aloft farther north around high pressure in the northeastern Pacific, before dipping southward into the northern U.S., limiting arctic intrusions in the East.
A more variable moist Pacific jet beneath the ridge of high pressure feeds rounds of rain and mountain snow into the Western states, including more intense “atmospheric rivers” that represent plumes of subtropical moisture thousands of miles long and several hundred miles wide.
Nine atmospheric rivers between Dec. 27 and Jan. 16 brought historic rainfalls and deep high-elevation snows to California, triggering deadly flooding and disastrous mudslides. The long-term benefit of heavy interior rain and as much as 25 feet of snow burying parts of the Sierra Nevada Mountains is much higher reservoir levels after years of exceptional drought.
In La Niña, arctic air is shunted north and east of the Ohio Valley region during much of the winter. The result was a very mild January in Columbus (7.8 degrees above normal) and an equally balmy February, with no measurable snow.
NOAA is predicting a continuation of above-normal temperatures and precipitation through early spring in Ohio. and across the Southern and Eastern states. The Pacific Northwest eastward to the northern Plains are expected to have a colder-than-normal spring.
The temperature contrast and active storm track could bring a greater risk of severe storms in the Mississippi and Ohio valleys.
Of course, this is just an average outlook, and transient cold spells and some accumulating snow are likely in early March and possibly again at the beginning of springtime.
A switch to a relatively normal sea surface temperature regime in the tropical Pacific in the next few months is expected to have little significance in the short term while complicating long-range forecasting, because there is no strong climate forcing to tilt conditions one way or another.
According to NOAA, there is a 60% chance El Niño will develop later in the year–a flip to warmer water in the equatorial eastern Pacific heading into next winter.