Summer Heat Dome Builds Over Oklahoma

The rain chances are fading away and the seemingly endless summer sunshine is a reality in the days ahead. This comes after a brief respite from the heat Saturday following morning storms that left some of us with the last substantial rainfall for quite a while.      

In case your memory has faded from last summer, the “heat dome” refers to the high-pressure ridge in the jet stream that sets up equatorward of the polar jet stream usually mid-summer (see below). This routes storm systems in this westerly belt of upper-level winds well to the north and prevents any cold front from reaching us easily. Therefore, the same air mass in place just gets reinforced each day by the high sun angle, and mostly clear skies allow for additional heating.  These heat domes are responsible for most heat waves and contribute to the most weather-related deaths in an average year. It’s nothing to downplay even though it's commonplace in the summer.

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This particular heat dome will be centered to our west most of the week over the Rockies. It will slowly expand across the Southern Plains before retracting back westward by next weekend. Our temperatures will follow that pattern, peaking midweek with at least minor heat relief by the weekend. Above, is our midweek set-up, showing the ridge overhead and the jet stream and storm track well to the north of Oklahoma. All the while, we’ll see few clouds in our sky and no disturbance to tap into our heat and humidity to generate storms. The only exception will be for southeastern Oklahoma where small-scale wind patterns around the varied terrain may allow isolated storm formation in the afternoon hours. It looks like Tulsa remains high and dry in the meantime. If it wasn’t for our recent bouts of rain in the past week and a 6”+ surplus compared to average for the year so far, it’d be a recipe for a flash drought.

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Rain chances do come back into the picture by the weekend as the heat dome’s adjustment westward allows the jet stream to sink south towards us on its periphery. This creates the open door for more clouds and the chance of rain or storms with a backdoor cold front as shown above. A week from now, temperatures may even briefly dip back below normal before rising again in the following week. The Outlook through the 3rd week in July is shown below. The long-range pattern through mid-July supports strong upper-level ridging, keeping that heat in place. Fittingly, July 10th is Tulsa’s first average 100° day and it won’t be long before we reach it.  Our high levels of humidity so far this summer have kept us below the century mark. However, this week and likely in the next, our heat index will daily climb above 100°. This puts loss of stress on our bodies when we work outdoors in it (along with our pets) so be sure to take it easy during the heat of midday and afternoon.

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Enjoy the summer weather, but don’t risk being overheated! It’s a pretty steady-state forecast for the week ahead, but we’ll some changes likely by the weekend. For more of my weather updates, be sure to follow me on Twitter: @GroganontheGO and like my Facebook Page.