NWS: May 2017 eighth wettest on record in central Indiana

Thursday, June 1, 2017

With precipitation reported on nearly two-thirds of its days, May 2017 finished as the eighth-wettest May on record in central Indiana since weather records began in 1871, the National Weather Service reported.

Rainfall was recorded in the Indianapolis area on 18 of the 31 days in May.

Monthly precipitation was above normal for all of Indiana except for the northwest and southwest portions of the state. Monthly totals ranged from slightly less three inches in northwest Indiana to more than 10 inches in portions of south central and southeast Indiana. Totals in central Indiana varied from five to nearly 10 inches.

Heavy rains were a frequent occurrence during May. An inch or more of rain fell somewhere in Indiana at the beginning of May, the 3rd through the 5th, the 9th through the 10th, the 19th through the 21st, the 24th through the 25th and the 27th through the 29th.

The only real dry spell for the state occurred from May 11-17.

The dry spell during the middle of the month allowed all flooding to end except for the Wabash River in the Riverton area. The return of rain on the 19th brought renewed flooding to the Wabash River. Rains during the remainder of the month prolonged the flooding along the Wabash River and will extend the high water into June. The Wabash remained near or above flood stage for the entire month of May.

One of the worst flash flood events in Indiana history occurred during the late afternoon and early evening May 19 just south of central Indiana. Torrential rains fell in the Salem area, and in less than four hours, rains of more than six inches were recorded.

The West Fork of Blue River at Salem rose over 16.5 feet from 3:30 p.m. to crest at 10:15 p.m. The rate of rise approached nine feet per hour just before the United States Geological Service (USGS) equipment maxed out at 7:30 p.m. The catastrophic flash flood caused millions of dollars of damage and was among the worst to strike Indiana.

Temperature-wise, the cool and wet weather at the end of April continued into the first several days of May with most locations remaining below 70 degrees for highs until May 9. Several locations were unable to rise out of the 40s on May 4, including Indianapolis with a high of 48 degrees, the coolest daily high temperature recorded in May since May 6, 1989 when the high only made it to 47.

After frosty mornings in the 30s May 6-8, temperatures warmed briefly into the lower 80s by May 10 before slipping back into the 60s and lower 70s. Beginning May 14, an extended string of warm weather saw daily highs above 80 degrees, peaking in the mid and upper 80s on May 18.

The passage of a cold front on May 21 brought cooler air south into the region. Highs in the 60s and low 70s were common before upper 70s and low 80s returned for Memorial Day weekend and the last few days of the month.

Overall across central Indiana, temperatures for May averaged near normal, with all main sites except for Lafayette finishing the month within a degree of average.

For central Indiana, 12 days had above-normal average temperatures, 15 days had below-normal average temperatures and four days had normal average temperatures.

May 2017 was tied for the 68th coolest in the Indianapolis area since 1871.

Multiple severe weather events impacted central Indiana throughout May. Damaging winds accompanied thunderstorms the evening of May 10 and early morning of May 11 from the Wabash Valley east through the southern portions of the Indianapolis metro area. Numerous trees were downed along with damage to structures and homes in Vigo County by winds estimated at up to 70 mph.

Severe storms erupted again May 20 as a supercell tracked across Clinton and western Howard counties, producing a small EF-1 tornado in the village of Forest that caused damage to a pole barn and a fire station. A second EF-1 tornado occurred just west of Thorntown in Boone County, causing damage to a barn.

Severe weather again impacted central Indiana at times over the Memorial Day weekend. Severe storms developed over central Illinois on the afternoon of the 26th, tracking into western portions of central Indiana during the evening.

A supercell produced large hail up to golf-ball size through Warren and Fountain counties before developing into a squall line with damaging winds up to 70 to 75 mph through Montgomery and northwest Hendricks counties. Significant wind damage occurred in Crawfordsville with numerous large trees and business signs downed.

Meanwhile, the Climate Prediction Center outlook for June indicates a greater chance for below-normal temperatures for central Indiana. At Indianapolis, the average temperature for the month is 72 degrees.

The outlook also calls for a greater chance of above-normal precipitation. The average precipitation for June at Indianapolis is 4.25 inches.

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