Zonal pattern to bring more heat, storms

After a soggy Fourth of July, we managed to get in a very nice weekend with seasonable temperatures and lower humidity. But the heat and humidity is returning this week and so will the chance for storms.

A storm system over the Pacific Northwest which brought unusual summer snow to the higher elevations in the northern Rockies is slowly pushing east. While the zonal – west to east flow – of the jet stream will keep the unseasonably cold air to our north, a storm system will still force a cold front into the Great Lakes on Thursday.

Before the cold front gets here, high pressure which controlled our weather over the weekend will head to the East Coast. The flow around high pressure is clock-wise, so this will pump up heat and humidity from the south into the Ohio Valley. This will increase the temperatures into the upper 80s to near 90 degrees with the heat index back well into the middle to upper 90s. The hot and humid air will be somewhat unstable and afternoon heating may spark thunderstorms the next few days.

By Thursday, the jet stream will dip slightly into the Ohio Valley allowing a cold front to swing through our area. There should be enough ingredients coming together to allow for the chance for a few strong, possibly severe storms depending on the exact timing of the front. Behind the front, the weather will quiet down and humidity levels will drop slightly to end the week.

Don’t look for the break from the heat or humidity to last as both will quickly return by the end of the coming weekend. As we head toward the heart of summer the second half of July into August, it appears we will see temperatures continue to rise. The latest long-range forecasts from the Climate Prediction Center suggest temperatures will stay above average well into August.Typically, we also see less organized severe weather later in the summer as the jet stream retreats further north into Canada.

While forecasting long term severe weather threats is difficult, we do know that overall precipitation amounts are expected to remain near or below normal for the next two weeks. Currently, much of the Miami Valley has a rainfall deficit of between 1 to 2 inches since June 1. It is likely we will see this deficit slowly grow the remainder of the summer, but as I mentioned in my article last week, so far, crops across the Miami Valley are fairing well. That could change if the rainfall deficit were to increase more rapidly in the coming weeks, which is not expected.

Eric Elwell is WHIO StormCenter 7 Chief Meteorologist. Contact him at eric.elwell@coxinc.com or follow him on Facebook and Twitter.

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