Our first taste of cooler air came in this evening as storms developed just west of the region and plunged across the Tulsa metro area. It was incredibly refreshing compared to the 104° heat index in the city just an hour before the outflow from the storms arrived. This marked the start of a new weather pattern that will bring a series of storm systems to Green Country and break our early season heat wave.

                As we kick off our Monday, an ill-defined frontal boundary will lie across the area. That will bring an additional focus for showers in the morning hours and a few storms by afternoon. The edge will be taken off the heat with additional cloud cover and a turn to a more northerly breeze during the day. Some places may not even make it into the 90s!

                Tuesday and Wednesday will likely be the driest days of the week with only a weak impulse or two traversing the area.  Temperatures will cool into the 60s at night for many places, but with sunshine, we’ll still end up in the lower 90s. It’s nothing to complain about for late June.

                Late Wednesday through the holiday weekend will be a period of unsettled weather. The culprit? Northwesterly flow in the jet stream. Think of it as a conveyer belt of storm systems that can race through the area. Some of these may be in the form of Mesoscale Convective Systems (MCSs). That’s a fancy term for a squall line followed by a generally long period of rain and thunder. They sometimes bring strong and damaging winds and the potential for flash flooding. Not all of them will be that intense, but we may see a series of those systems and redevelopment on subsequent outflow boundaries daily.

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                At this point Friday appears to be the day with the strongest upper level wave passing over the state, which will result in the most widespread rain and storms… perhaps an MCS.  The chance will linger into the holiday weekend itself, although the ridge of high pressure (that oppressive heat-maker) will start to build back over the area and send that storm track, at some point, off to the northeast again. It’s too early to say how big of an impact storms will have for the festivities across Green Country this weekend. However, the closer to the 4th of July they are, the more likely it seems they could be spared from a downpour.

                Regardless of the timing, this rain is welcome news. The year-to-date rainfall deficit is now over 6” in Tulsa (measured at the airport) and a low-end drought situation has started to develop. Hopefully this weather pattern will nip it in the bud. Rain totals, as shown below, could top 3” over the week ahead.  That’ll be a nice dent in the deficit.

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                Enjoy the cool-down and periodic rain this week. Be sure to follow me on Twitter: @GroganOntheGO and on my Facebook page for more weather updates!