Expected rain could smash record for wettest June in St. Louis-area history

Heavy rain and cooler temperatures are on the way to the metro-east for the next several days.

By the time the storms clear, this could end up as the wettest June in the recorded history of the St. Louis area.

“We could see 5-7 inches of rain by the end of the week in a wide swath across the Midwest,” National Weather Service meteorologist Fred Glass said. “But some localized spots could easily exceed 10 inches of rain.”

So far this month we’ve already had 6.01 inches of rain in the St. Louis metropolitan area, Glass said.

The all-time record for precipitation during the month of June in the St. Louis metropolitan area is 12.35 inches, according to the National Oceanographic and Atmospheric Administration. So if the expected rain hits the higher end of the predicted range, the previous record will be smashed — with a week to go in the month.

The current rainfall total for the month already makes this the 28th wettest June since 1874, when records began to be kept. If the area gets five inches of rain, the lower end of the prediction for this week, it would be the second-wettest June on record, beating out the 10.84 inches of rain that fell in that month in 1875.

Glass said the rain, which will be heaviest late Tuesday night into Wednesday morning and late Thursday, shouldn’t be taken lightly.

Some of the storms could be severe, and flash-flooding is a possibility. Rivers are expected to jump out of their banks.

“All of that water is going to go into the river system, which is already flooding,” Glass said. “It could reach major flood stage in some spots.”

“So we’re already about 3 3/4 inches above normal for the month before the big storms hit,” Glass said.

The excessive rain comes from a combination of factors, according to Glass: There is a lot of moisture in the upper atmosphere because of a high-pressure system parked over the Midwest. So when a relatively normal storm front moves into the area, it will be fueled by all the moisture in the atmosphere to make the rain more prolific. Later in the week, Tropical Storm Bill, which made landfall Tuesday near Houston, will collide with the jet stream and turn northeast to bring additional rain to the area.

“While the rain we’ve had over the past couple of days has been scattered, the coverage will be much more widespread in the coming days,” Glass said.

There was a 70 percent chance of showers and thunderstorms forecast for the daytime hours Tuesday with a high temperature of 81, according to the National Weather Service.

The chance of storms increased to 80 percent Tuesday evening, when the low was expected to be 72.

On Wednesday, the high is forecast to be 83 with an 80 percent chance of storms and showers during the daytime hours. In the evening, the chance of wet weather is 70 percent with a low of 70.

The chance of storms and showers will be 70 percent during the daytime hours Thursday, when the high will be 81.

Thursday night, the low will be 68 and the chance of thunderstorms is estimated at 60 percent.

The U.S. Army Corps of Engineers announced Tuesday that flooding has forced the closure of day use and camping areas along the Kaskaskia River. The lock and dam on the river is also expected to soon close.

Meanwhile, Corps leaders warn boaters and anglers that the Kaskaskia River current is especially swift and the water is full of debris lifted from the shoreline.

In the average June, the St. Louis metropolitan area gets about 2.26 inches of rain.

The Mississippi River has risen five feet over the past two days at the St. Louis riverfront to 30 feet, the threshold of minor flood stage. By the time the rain of the upcoming week is added to the system, the river is expected to reach 34.4 feet by Saturday. That’s just below the threshold of moderate flood stage, 35 feet.

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This story was originally published June 16, 2015 at 6:55 AM with the headline "Expected rain could smash record for wettest June in St. Louis-area history."