Stormy Pattern Making a Return

After several rounds of storms over the weekend, we are catching a small break in the active weather pattern. Soaking rains fell over most of Green Country, filling many of our reservoirs higher than their normal levels for the first time this year like Skiatook Lake.  In fact, minor flooding even occurred along Bird Creek north of Tulsa. More heavy rainfall is likely at the end of the week, which may be coupled with severe storms for some of us.

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                The first round of storms may arrive late Wednesday night with the arrival of a cold front. We’ll be catching the leftovers here in Oklahoma with the greater severe threat to our north in Kansas as the map above shows. Where that front ends up from Thursday into Friday will be a major factor in who gets the severe weather late this week. A few storms may re-fire along that boundary Thursday in the heating of the day. The biggest rain-maker holds off until that night into Friday though.

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                A second, more powerful upper-level wave will override that surface front stretched across the state, creating widespread heavy rain and storms along and north of that frontal boundary as air rises up and over it ahead of the low pressure. Our Friday will begin wet with lots of rain falling in northeast Oklahoma. Daytime heating along and south of that front will create a primed atmosphere for severe storms. As of now, that area appears to be along and south of I-44 and more likely south of I-40. The map below shows a product called the “Supercell Composite,” which puts together multiple parameters that lead to severe and rotating thunderstorms.  The highest risk as you see appears to be along and south of the low pressure with the warm front demarcating the northern extent of the severe risk near the Tulsa area at 7pm Friday. There are still differences from computer model to model and run to run on exactly where the greatest severe threat will be, including the risk for tornadoes. Most likely though, it’ll be in southern Oklahoma where the air mass will be more unstable.

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                The biggest issue with this storm system will be the amount of rainfall we see. The east-to-west orientation of the frontal boundary with east-to-west movement of storms along that boundary will lead to a corridor of high rain totals thanks to those training storms on Friday. As much as 5” to 6” of rain may fall in a relatively small time window, creating a risk for flash flooding. Below are projected rain totals in our area.  Even though the severe threat may be higher, further south, northeast Oklahoma may end up with the most rain.

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                This is a deep storm system that will draw in much cooler air behind it. We’ll straddle the boundary of cooler air on Friday in Tulsa, but by Saturday, that colder air will rush in and bring temperatures 10° to 15° below normal. Over the weekend as we dry out, expect morning lows in the 40s with highs only around 60° on Saturday. We’ll have to bust out at the heavier jackets at least one more time this season!

                A much-needed window to dry out will follow into next week with seasonable temperatures. The storm pattern ramps up again by the end of next week, bringing us back to a wetter than normal pattern for the end of the month. By this point, it’s likely much of northeastern Oklahoma will be out of drought with improvement further south in the state.

                For more weather updates, be sure to follow me on Twitter: @GroganontheGO and on my Facebook Page.