From NWS
1997

1990: Slow moving thunderstorms produced 4 to 8 inches of rain around Sioux City resulting in a record crest more than 7 feet over flood stage on Perry Creek. This flash flood caused the evacuation of about a thousand homes and produced at least 4.5 million dollars in damage. There was also flash flooding in Crawford and Plymouth counties, with a hundred hogs killed on one farm near Denison as 8 to 10 feet of water flooded a barn after 3.5 inches of rain fell in just over an hour.

1934: One of the hottest summers on record in Iowa began in earnest with very hot May temperatures reaching 104 F near Inwood on the 18th. Other high temperatures that day included 102 F at Spencer, 101 F at Rock Rapids, and 100 F at Pocahontas. At Des Moines the month would finish as the warmest May on record with an average temperature of 71.1 F.

1898: A severe thunderstorm produced a long-lived violent tornado and very large hail as it tracked from Cedar County through Clinton and Jackson counties then crossed the Mississippi River into Illinois. The storm killed 19 people and injured at least 40 others in Iowa with another 9 killed and more than 100 injured in Illinois. Amazingly the tornado grazed more than a dozen towns along its path but failed to directly strike any of them, otherwise the casualties would likely have been far more numerous. Many lives also appear to have been saved by the fact that the tornado moved unusually slowly, traversing the 30 or 35 miles between Lost Nation and Preston in an hour and 20 minutes. An account in the Maquoketa Excelsior newspaper noted that a freight train easily ran ahead of the storm. This slow forward motion allowed warning to be sent from communities grazed by the tornado to those further along its path and many took shelter as a result. An observer near Stanwood reported hailstones to the size of walnuts falling from the storm with “much larger stones two miles northwest of here” while on the steam boat Saturn, two miles south of Sabula on the Mississippi River, an observer wrote that hail fell on the deck “in great quantities, chunks being found as large as a man’s fist” and that “the barrels on deck were filled with the ice.” At Preston hailstones were measured as large as 14 inches in circumference.

1892: Several weeks of wet weather took the Floyd River in Sioux City to bank full, then heavy rain on May 17th into the early morning of the 18th led to one of the worst flash floods in Sioux City history. The flood swept down the Floyd River between 6 and 7 am on the 18th, sending residents scrambling into trees or onto roofs. One observer wrote that “the first intimation was a volume of water spreading over the banks to a depth of three feet and throwing a mist of foam from it. In a few minutes the water had risen above the first floors and several thousand fled in terror to the higher ground. The water rose eight feet in one hour and a half and from nine o’clock continued to rise steadily but not so rapidly.” At its highest point it was reported that the river swept from the base of Floyd’s bluff to Court Street on its way into the Missouri River. The lumber yards, stock yards, and railroads were all severely damaged or destroyed and at least 2,000 head of livestock were drowned and seen floating down the river. Both electric plants were inundated, cutting power to the city for some time, and all business and transportation in the city were suspended. At least 25 people were drowned in the flood and several thousand were left homeless.

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UPDATED at 4:15 PM

Tonight: Partly cloudy. Low: 57-61. Wind: SE 5-10 mph.

Saturday: Partly cloudy. High: 82-86. Wind: SE 10-15 mph.

Saturday Night: Partly cloudy and warm. Low: 62-66. Wind: SE 5-10 mph

Sunday: Partly cloudy and windy (SE 15-25 mph) with a 60% chance of showers/storms. High: low-mid 80s.

Monday: Mostly cloudy and windy (S 15-25 mph) with a 60% chance of showers/storms. High: low-mid 80s.

Tuesday: Mostly cloudy with a 30% chance of showers. High: mid-upper 70s.

Wednesday: Partly cloudy with a 20% chance of showers. High: near 70.

Thursday: Partly cloudy. High: near 70.

Friday: Partly cloudy. High: low 70s.

A stationary front currently located east/west across Iowa may trigger isolated showers/storms this evening. Any showers/storms will fall apart as the sun sets. The sky will be partly cloudy tonight through Saturday night.

Saturday will be warm and a little more humid than Friday as the stationary front slowly drifts north of Iowa.

We are still tracking the chance of severe weather for Sunday. Storms west of Iowa Saturday will be moving east and falling apart Saturday night. A few might make it as far east as eastern Iowa by Sunday morning. The sky will be partly cloudy Sunday. It will also be warm, humid and windy. The cold front and low is forecast to slowly push east with thunderstorms developing in the afternoon and evening. The following severe weather is possible Sunday afternoon/evening: large hail, high winds, flooding rain and a few tornadoes. The maps below show the forecast position of the low and fronts in addition to the slight risk area and the best chance of severe weather within that risk area.

If you have been following the forecast and blog forecasts you know that there was a chance of severe weather across eastern Iowa on Monday as well. The latest information indicates that will may still see some showers/storms but the threat for any severe weather would be south of Iowa (see map below).

Rain showers are still possible Tuesday and Wednesday as this low slowly moves east. High temperatures will cool to near 70 Wednesday and Thursday. Dry weather is forecast for Thursday and Friday as high pressure moves into the Midwest.

From NWS
1996

1902: Slow moving thunderstorms produced very heavy rainfall and flash flooding across portions of far northeastern Iowa. Observers in Fayette and Postville measured more than 5 inches of rainfall in just a few hours. At McGregor the storm was accompanied by a terrific display of lightning which struck several buildings downtown including a saloon and billiard hall that was demolished. Flood waters flowed through most of the town, sewers backed up, and there was considerable damage to most structures in the area. Four people were injured in McGregor.

1877: Large hail fell at Hamlin in Audubon County where stones 6 inches in circumference smashed windows and crops, stripped the bark from trees, and killed many small animals.

17 May 1896 → A 2-mile wide path of utter destruction, made up of a nearly mile-wide F5 tornado plus powerful downburst winds, swept for 100 miles across northeast Kansas and the southeast corner of Nebraska. Seneca, KS was particularly hard hit and lost its opera house. Twenty-five people were killed. 17 May 1979 → It does get cold in Hawaii! The state’s record low was set on Mauna Kea, bottoming out at a rather chilly 12 degrees. 17 May 1983 → A golfer playing the Fox Meadows course in Memphis, TN was struck by a bolt of lightning that went through his neck, down his spine, came out a pocket containing his keys, and went into a nearby tree. He survived.

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UPDATED at 4:30 PM

Tonight: Partly cloudy with a 30% chance of showers/storms. Low: 55-60. Wind: SE 5-10 mph.

Friday: Partly cloudy with a 50% chance of showers/storms. High: 75-81. Wind: SE 10-15 mph.

Friday Night: Partly cloudy. Low: 57-61. Wind: SE 5-10 mph.

Saturday: Partly cloudy. High: low 80s.

Sunday: Partly cloudy with a 60% chance of showers/storms. High: low-mid 80s.

Monday: Partly cloudy with a 60% chance of showers/storms. High: low 80s.

Tuesday: Mostly cloudy with a 50% chance of showers/storms. High: mid 70s.

Wednesday: Mostly cloudy with a 20% chance of showers. High: upper 60s.

Thursday: Mostly cloudy with a 20% chance of showers/storms. High: near 70.

It has been a beautiful spring day with high temperatures in the low 80s, low humidity and a light SE wind. A warm front is located east/west across southern Iowa. Along and south of the front it is humid with dewpoints in the 60s.

The warm front is going to gradually move north across Iowa tonight and Friday. Along the front later tonight and Friday showers and storms are forecast to develop. The map below show the forecast postion of the warm front at 1 pm Friday.

Some of the storms could be strong Friday afternoon, but at this time are not expected to be severe. Saturday through Monday will be humid with dewpoints in the 60s across all of eastern Iowa. Saturday will be a dry with highs in the low 80s. Sunday and Monday are the two days we have been tracking for the potential of severe weather. At this point severe storms are possible. The map below shows the areas where severe is possible Sunday and Monday. The forecast surface map is located below the outlook areas.

The chance of severe storms would be late Sunday afternoon through Monday. The threat from these storms would be hail, high winds and a few tornadoes. Stay up to date on the forecast through the weekend for the latest on this possible severe weather.

Showers and storms are still possible behind the cold front Tuesday, but I am not expecting any severe storms. Wednesday and Thursday will be cooler with highs in the upper 60s. Showers and a few storms are still possible with the next low pressure system.

From NWS
1999

1997: A very unusual weather scenario resulted in Sioux City breaking both its record high and record low temperatures for the date with a morning low of 33 F and an afternoon high of 91 F.

1899: A tornado produced F4 damage along a track from near Greeley in Delaware County to northwest of Colesburg and into southern Clayton County. In one family near Greeley two people were killed and four others were severely injured. Another two people were killed and 10 more injured further along the path of the tornado in Clayton County.

1886: Several days of thunderstorms and scattered severe weather on May 12-14 were followed by an unseasonably strong cold front on the 15th. During the latter part of the day on the 15th light snow was observed mixed with rain in Clayton and Scott counties, and on the morning of the 16th a widespread frost covered nearly the entire state. An observer near Iowa City noted “white frost on fields. The sycamore maples in Iowa River Valley just north of town were frosted, some leaves turned brown.”

16 May 1874 → A flash flood caused by dam slippage claimed 143 lives and a million dollars in property damage at Mill Creek, west of Northhampton, MA. 16 May 1951 → Hurricane Able performed a loop north of the Bahamas and reached Category 3 strength off Cape Hatteras, NC. 16 May 2010 → A significant hail storm struck the Oklahoma City metro area with baseball sized hail. It was one of the most damaging and costly hail storms in Oklahoma history. The hail produced significant damage to automobiles, roofs, and vegetation and was accompanied by winds in excess of 50 MPH. Hail drifts several feet deep were reported, and some locations had hail still covering the ground 12 hours after it fell. Damage estimates exceeded $500 million.

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