Flooding may impact parts of central Iowa on Wednesday after heavy rains from overnight thunderstorms, according to the National Weather Service. 

Flood warnings were issued for areas near Boone and Ames. A flood warning was issued around 7 a.m. Wednesday for the South Skunk River after 2 to 5 inches of rain fell in parts of Boone, Hamilton, Hardin, Marshall and Story counties during overnight thunderstorms. Flooding on the river may affect parts of Story and Polk counties Wednesday and Thursday. 

At 6 a.m. Wednesday  the South Skunk River was at 16.7 feet. It is expected to crest at 22.5 feet just after midnight Thursday, according to the warning from the NWS, one foot over flood stage.

Any impacts from flooding of the river are expected to be minor, according to the warning. But at 23 feet the Shady Grove Mobile Home Park in Ames and a railroad flood, according to the NWS. 

A separate flood warning for Story County urged motorists to be "especially cautious" at night when it is harder to recognize the dangers of flooding. 

"Turn around, don`t drown when encountering flooded roads," the warning said. "Most flood deaths occur in vehicles." 

A flood warning was issued around 8 a.m. for Boone, Hamilton, Hardin, Marshall and Story Counties until 3 p.m. Wednesday. Streams continue to rise because of runoff from rainfall overnight. 

Since midnight, 4.8 inches of rain has fallen in Boone, according to WHO-TV. 

Rainfall totals also reported by WHO include:

More showers and thunderstorms are possible in central Iowa between 1 p.m. and 7 p.m. as a cold front moves through, according to the NWS. Large hail is the primary threat, but wind gusts between 60 and 70 mph are possible. Up to an additional inch of rain could fall, according to the warning. 

Flooding is ongoing or expected to begin in the warned areas, according to the warning. Locations that will experience flooding include Ames, Nevada, Story City, Roland, Jewell Junction, Gilbert, Hubbard, Zearing, Radcliffe, Ellsworth, Union, McCallsburg, New Providence, Randall, Buckeye, Saint Anthony, Garden City, Drake Airport in Radcliffe and the Iowa Falls Municipal Airport, according to the NWS. 

Since Jan. 1, Des Moines has gotten 2.66 inches less precipitation than normal, according to the NWS. In June the city has gotten about 2 inches of rain, about a half-inch less than normal. 

Most of central and eastern Iowa emerged this spring from a drought which hurt farmers last year. Monona, Woodbury and Plymouth counties in Western Iowa remain in severe droughts as they are the easternmost areas affected by a drought which is gripping the western half of the Unites States.  Since Jan. 1 Sioux City has gotten 5.85 inches less precipitation than normal, according to the NWS. 

There is a "slight chance" of thunderstorms and rain showers in Des Moines Thursday night, according to the NWS. The weekend looks to be mostly sunny, but highs will gradually increase from 88 degrees Friday to 98 degrees Sunday. 

Philip Joens covers public safety, city government and RAGBRAI for the Des Moines Register. He can be reached at 515-443-3347 at pjoens@registermedia.com or on Twitter @Philip_Joens.