Some Phenomenal Rainfalls the Past Week in the U.S.
Exceptionally intense rainfalls have occurred in such diverse locations as Vermont, North Dakota, Iowa, and Texas over the course of the past week or so. Iowa has recorded its wettest spring on record, since 1872. Herein is a brief recap.Vermont
Although the unseasonable Memorial Day weekend snowfall in Vermont (and New York) stole the headlines recently, the storm also brought excessive record-breaking rainfall and floods to the state. Burlington received 7.47” of precipitation over the course of the week of May 20-26. This ranked as the 2nd wettest week in the city records, surpassed only by a 7.51” weekly total in August 1955, the result of two hurricanes (Connie and Diane) that impacted the region. In fact, for the 5-day period of May 21-25 it was the wettest such period on record (7.01” vs. 6.66” during August 1955). Burlington also experienced 4 consecutive days with 1.00” or more rainfall (5/22: 1.43”, 5/23: 2.26”, 5/24: 1.13”, 5/25: 1.23”), something that has never occurred previously.Rainfall totals for the NWS-Burlington forecast area over the 6-day period of May 21-26. A peak amount of 9.59” was recorded near Underhill, Chittenden County.
Map from NWS-Burlington office.Significant flash flooding occurred over a large part of Vermont during the rainstorms. Road washouts were common in the Jericho area where 4.06” of rain fell in the 12-hour period between 7 p.m.-7 a.m. May 23-24.
Photo by Ryan Mercer for the Burlington Free Press.San Antonio, Texas
The most noteworthy precipitation event of the past week was the downpour that inundated San Antonio, Texas on May 24-25. An amazing 12.17” of rain fell in a 24-hour period between noon May 24 and noon May 25. This was the 2nd greatest 24-hour rainfall on record for the city (the all-time record being 13.35” on October 17-18, 1998). Precipitation records go back to 1871 in San Antonio. The storm has also brought the May monthly precipitation total to 13.19” so far (more rain expected Wednesday), close to the all-time May monthly record of 14.07” in May 1935. Massive flooding engulfed the city resulting in three drowning deaths and hundreds of emergency water rescues, many involving rooftop extractions.The San Antonio River at LOOP 410 (where the river flows under I-410) rose 30’ in just four hours the morning of May 25th. The river peaked at a record stage of 34.21’.
USGS.Northeastern North Dakota
One of the most significant rain events in North Dakota history occurred over the 3-day period of May 18-20. Grand Forks AFB measured 5.89” over the course of precipitation period and in the very far northeastern corner of the state an astonishing 9.50” was recorded at Milton 6 NNE and 9.00” at Walhalla 3 S. It is not clear what the greatest 24-hour total may have been at any one location, but the state record for such is just 8.10” at Litchville on June 29, 1975, so this gives you an idea of just how unusual rainfall of this intensity is for the state. Grand Fork’s all-time 24-hour precipitation record is 4.44” on July 16, 1995, this was not challenged by the recent storm. Flooding caused the evacuation of a few homes in sparsely populated Pembina County around the town of Crystal.Rainfall totals for the 3-day period of May 18-20 in northeast North Dakota and northwest Minnesota (the state boundary runs down the middle of this map). Local excessive amounts of over 9” were measured in Pembina County near the Canadian border.
Map from NWS-Grand Forks office.Northeastern, Central Iowa
Excessive rainfall pounded a large area of the Midwest on May 26-27. Lincoln, Nebraska measured 3.32” in a 12-hour period on May 27th. Just short of their all-time May 24-hour precipitation record of 3.35” set on May 5, 2007. Kansas City International Airport picked up a quick 1.02” in 30 minutes on the morning of the 27th. But it was in northwestern and central Iowa that the greatest rainfalls and worst flooding ensued. Unofficial reports of 10” of rain in 24 hours were said to have occurred near Storm Lake, Iowa and 9” in Aurelia. The rainfall caused the Floyd River at Alton to crest at an all-time record high flood stage of 19.1’ (previous record was 18.’ On June 20, 1983). The Little Sioux River also crested at or above its highest recorded stage at 11.25’ on May 27th. In central Iowa the Iowa River has spilled its banks in Marshalltown (pop. 25,000) and cut of Hwy. 14, the principle artery serving the city.
The Iowa State Climatologist, Harry Hillaker, announced
this morning (May 29th) that this has been the wettest spring (March-May) on record for the state since records began 141 years ago. A state average of 16.4” has been preliminarily reported. The previous wettest spring was 15.5” way back in 1892. He warns that “Iowa is at a tipping point for a major flood event”.
Christopher C Burt