ELWELL: Winter may start quiet, get increasingly bitter

Late last week, the National Oceanic and Atmospheric Administration released its winter weather outlook for the 2018-2019 season.

In case you missed it, the forecast is calling for another El Nino winter.

El Niño is a part of a routine climate pattern that occurs when sea surface temperatures in the tropical Pacific Ocean rise to above-normal levels for an extended period.

The warm water in this region influences the jet stream, and thus the storm track across North America. This can have dramatic impacts on the weather across the United States including in the Ohio Valley.

According to NOAA, there is a 70 to 75 percent chance of El Nino to develop before winter begins.

Typically, an El Nino pattern such as what is expected to occur would bring wetter -than-average conditions to the southern tier of the U.S., and up into the Mid-Atlantic. Northern Florida and southern Georgia have the greatest odds for above-average precipitation this winter.

Drier-than-average conditions are most likely in parts of the northern Rockies and Northern Plains, as well as in the Great Lakes and northern Ohio Valley. Warmer-than-normal conditions are anticipated across much of the northern and western U.S., with the greatest likelihood in Alaska and from the Pacific Northwest to the Northern Plains.

Over the last few weeks, our Storm Center 7 team of meteorologists has been digging deeper into the current weather pattern to help determine what our winter may have to hold for us. To do this, we must look beyond just whether an El Nino or La Nina weather pattern will develop.

There is a lot more that goes into what type of winter we will have here in the Ohio and the Miami Valley.

In our part of the world, the Arctic Oscillation plays a huge role in our temperature pattern. Basically, we pay very close attention to what the circulation pattern is over the arctic circle and around the north pole.

A strong polar vortex would tend to keep the coldest air locked in far northern Canada. But a weak vortex means a wobblier jet stream. This typically favors cold surges deep into North America and many times right across the Eastern United States.

Forecasting what the Arctic Oscillation will look like more than a few weeks away is very difficult, if almost impossible. However, we can look at other patterns that influence the AO such as El Nino and even the past hurricane season to get an idea of what the winter may hold.

Looking at our current weather pattern over the last few months up to now – as comparing it to similar past patterns, it appears we are matching up fairly close to the pattern we had in the winter of 2014-2015.

Using analog forecasting techniques (a method involving averaging weather statistics accumulated over many years to make the forecast), our Storm Center 7 forecast is calling for a relatively quiet December with low precipitation and near or even above normal temperatures. The month of January will tend to be much more typical of an Ohio winter with average amounts of cold and snow, but perhaps with relatively short-lived cold shots. If history is a good guide, similar patterns have typically brought the most severe cold, and perhaps heaviest snow in the month of February. This may be when we see nearby visits from the “polar vortex”. Indeed, February could tend to be below average temperature-wise with normal precipitation.

March is more of a wildcard. If our pattern follows similar to early 2015, we may struggle to warm up in March and the month could begin snowy. The month of March during past weak El Nino phases have brought active weather in our region with fairly wild temperature swings.

In my 20 years now in Ohio, I have always told people to keep a close eye on the weather pattern that develops near and around Thanksgiving. This can give you a good idea of the winter that is coming. If you start to hear of heavy snows in the Northern Plains or even in southern Canada, then that will likely set the ground work for plenty of cold to head south in time for Christmas.

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