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Some Phenomenal Rainfalls the Past Week in the U.S.

By: Christopher C. Burt, 8:33 PM GMT on May 29, 2013

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
Weather Historian

Extreme Weather Precipitation Records Flood

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Great post, thanks!

Amazing how fast we have gone from severe drought to severe flooding in so many places. How does vermont rainfall compare to hurricane irene? And in between was the hot and dry year of 2012. I remember in 2011 iowa had severe flooding which shut down a nuclear reactor, then the drought last year. I wonder what the damage estimates are from the san antonio flooding. The 21st century is getting crazy, the predictions of the effects of climate change are coming true. I dread what hurricane season brings, i live in nyc, time is running out.
Quoting mtwhitney:
Great post, thanks!

Amazing how fast we have gone from severe drought to severe flooding in so many places. How does vermont rainfall compare to hurricane irene? And in between was the hot and dry year of 2012. I remember in 2011 iowa had severe flooding which shut down a nuclear reactor, then the drought last year. I wonder what the damage estimates are from the san antonio flooding. The 21st century is getting crazy, the predictions of the effects of climate change are coming true. I dread what hurricane season brings, i live in nyc, time is running out.


Hurricane Irene dropped an unofficial 11.23" on Menden, Vermont on Aug. 28-30. How much of this fell in a single 24-hour period is not clear. Vermont's greatest official 24-hour rainfall seems to be the 9.92" that accumulated at the Mt. Mansfield site during Hurricane Floyd on Sept. 17, 1999. Either way, those events were more extreme precipitation-wise than the recent event. For a non-tropical storm we would have to go back to the great flood of November 3, 1927 when 9.65" fell at Somerset in 24 hours (probably greater amounts fell at mountaintop locations, but there were no weather stations there at that time). The 1927 flood killed 84 people in the state, Vermont's deadliest single weather disaster on record.
I live in DC suburbs and my two tropical cyclone fears are a SSE-NNW track just to
the west of Chesapeake Bay from a large Cat 2 or higher storm, or any track
that produces cat 2 or higher winds over the area.  Cat 2 winds were last experienced in 1954 with Hazel and we are vert  vulnerable to these rare events.  The infrastructure destruction from such winds would be enormous and
(I really hate to use the  overused word but it would apply)  unprecedented.

There is no record of a +10 foot storm surge running up the Potomac but the track above could produce one and it would flood the Mall and buildings around if it did so.  

On the other hand the closest F3 tornado track is only three miles from my house (The College Park 2001 tornado) so that's alarmingly precedented.




Isabel in 2003 and the 1933 hurricane produced large surges in the northern Chesapeake Bay.

I'd be interested in a systemic analysis of whether extreme rainfall events are becoming more frequent, as opposed to anecdote. For instance if in the last 20% of weather sites' observation periods 33% had record rainfalls. Or 40% or whatever.
"Hurricane Irene dropped an unofficial 11.23" on Menden, Vermont on Aug. 28-30. How much of this fell in a single 24-hour period is not clear. Vermont's greatest official 24-hour rainfall seems to be the 9.92" that accumulated at the Mt. Mansfield site during Hurricane Floyd on Sept. 17, 1999. Either way, those events were more extreme precipitation-wise than the recent event. For a non-tropical storm we would have to go back to the great flood of November 3, 1927 when 9.65" fell at Somerset in 24 hours (probably greater amounts fell at mountaintop locations, but there were no weather stations there at that time). The 1927 flood killed 84 people in the state, Vermont's deadliest single weather disaster on record."


Thanks for the reply, it puts this event in perspective. I see that the recent rains are over a period of up to a week, the other events happened in 1 or 2 days, making them more intense. It appears that the 1927 flood was probably america's greatest historicaly recorded national flood, it started in 26 and spread over a huge area, from the mississippi basin to the eastern US. The 27 flood inspired this great song,

http://www.youtube.com/watch?v=y2m0ROgy5WY

which was re-mastered by led zeppelin in 71.

So many places are getting hit by extremely heavy rainfalls from what appears to be ordinary thunderstorms, the NYC area had storms move through last friday with some areas getting 4 - 5 inches. At least the lawns and gardens are growing, and will not need watering for a while!
In case you haven't seen it, http://www.bbc.co.uk/news/uk-22718944 .... thought it was distinctly chilly, even by NW England standards a daily high of 13C late in May is not what we expect!
Quoting BaltimoreBrian:
Isabel in 2003 and the 1933 hurricane produced large surges in the northern Chesapeake Bay.

I'd be interested in a systemic analysis of whether extreme rainfall events are becoming more frequent, as opposed to anecdote. For instance if in the last 20% of weather sites' observation periods 33% had record rainfalls. Or 40% or whatever.

I can't find the reference, Brian, but I'm fairly certain that UK Met office has done respectable research showing more extreme rainfall events this side of the pond, particularly through the 2000s.

Quoting BaltimoreBrian:
Isabel in 2003 and the 1933 hurricane produced large surges in the northern Chesapeake Bay.

I'd be interested in a systemic analysis of whether extreme rainfall events are becoming more frequent, as opposed to anecdote. For instance if in the last 20% of weather sites' observation periods 33% had record rainfalls. Or 40% or whatever.

I remember isabel.    The surge in the northern Chesapeake Bay was very large but it was not a maximal surge for the Potomac River in DC.
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