Humid air puts region at risk for potential flash-flooding

The summer solstice is upon us, but it appears the hazy, hot and humid weather arrived early. Temperatures soared over the weekend into the 90s as the first heat-wave of the year arrived in time for Father’s Day.

An official heat wave occurs when temperatures soar to 90 degrees or higher for at least three days in a row.

The Weather Prediction Center has placed much of the Miami Valley in a risk zone for flash flooding through the first half of this week.

As temperatures have climbed, so has the amount of moisture in the air. With the increase in humidity, it becomes quite uncomfortable to go outside for any long periods of time, especially late in the afternoon or early evening. The reason for this is because with more moisture in the air, the moisture your body produces to help you cool doesn’t readily evaporate.

Without that evaporation, your body will sweat easily, making you feel even more uncomfortable. After an extended period of time, serious heat related illnesses such as heat exhaustion or heat stroke.

The good news is as we head through the week, the heat will begin to ease a bit. Temperatures are forecast to drop out of the 90s and hold in the 80s for the next few days. Unfortunately, there will be very little relief in the humidity which will likely lead to a few issues. First, the humid conditions will increase the amount of mold spores in the air. This, in turn, can cause allergic reactions. Also, mosquitoes have been on the increase. Warm and muggy evenings are a favored environment for these pesky insects.

The biggest concern with the humid air may become the threat for heavy rainfall and an increased potential for flash flooding.

A very slow-moving frontal boundary will be sliding southward across the Miami Valley through the middle of the week. As it does, showers and storms will become more and more widespread across the area. These storms will have plenty of tropical moisture to work with, meaning rainfall rates from storms could become quite high. It is the type of environment that is forecast this week where flash flooding can become an issue. We saw similar flooding happen on June 8 which led to the closure of U.S. 35 of Dayton’s west side.

While forecasting exactly where flash flooding will occur is nearly impossible, this is a good reminder if you are traveling and you drive into an area with extremely heavy rainfall, slow down! Also, be sure you turn your headlights on to help with visibility when driving through rain..

You will also want to allow an extra 1 to 2 seconds of following time from other cars during heavy rain, just to give you some additional stopping distance if needed. Even if you don’t hydroplane, the cars around you could, so give yourself some space. Interestingly enough, Ohio law says the use of hazard lights on a moving vehicle is illegal except in unfavorable atmosphere conditions. I guess that means it is up to the law enforcement official what “unfavorable” would be. But I would think making yourself as visible as possible when visibility drops would be a good idea. Just remember though if you do you hazard lights, you still must turn them off to signal for turns and lane changes.

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