Information on this webpage is considered preliminary and will continue to be updated as the event is analyzed.

Anyone with information that could enhance the record of these storms should contact the National Weather Service Office in Tulsa at 918-838-7838 during business hours, submit an online storm report, or send us an email at: sr-tsa.stormreport@noaa.gov. Information can also be posted on our Facebook page.

 

Event Summary - April 29 - May 1, 2012 Heavy Rain and Flood Event - updated 9 am 5/07/2012

* Visit this link for a map of 24 hour rainfall totals from 7am to 7am.

* Visit this link for current River Flood observations and forecasts.

* Visit our Decision Support page for the lastest hazards forecast.

Three rounds of heavy rainfall over three days, with totals of 6" to 12" along the Oklahoma-Kansas state line, led to flash flooding and mainstem river flooding across northeast Oklahoma April 29-May 1, 2012.  Numerous swift water rescues, evacuations of many homes, and several road closures occurred during this mult-day event.

3 Days of Heavy Rain

A nearly stationary front located along a line from near Stillwater to near Bartlesville provided the focus for showers and thunderstorms during the overnight and morning hours of April 29. 0.5” to around 2” of rain fell northwest of I-44 from this activity.  The widespread rainfall gradually shifted north into Kansas during the day on the 29th before scattered shower activity renewed over north central and northeast Oklahoma during the afternoon hours. 

As an upper-level wave passed over the area late in the day April 29, more widespread and organized convection developed near the quasi-stationary boundary located northwest of I-44.  With the upper-level flow oriented along the stationary boundary, the same areas of north central and northeast Oklahoma that had the moderate rain on the 29th (in addition to southeast KS) experienced repeated rounds of additional heavy rain during the late evening of the 29th through the morning hours of the 30th.  The highest rainfall totals within the Tulsa County Warning Area (CWA) were 5”-8”, occurring over northern Osage and far northern Washington Counties.  In Burbank (Osage Co.), 1.44” fell during the first round of storms, followed by 3.26” the next night for a total of 4.70” (measurements from the OK Mesonet).  This rainfall over Burbank (and the even higher totals upstream) led to severe flash flooding in Burbank, necessitating swift water rescues and evacuations (by boat) of several homes on April 30th as Salt Creek flooded.  State Highway 18 near Fairfax was also closed due to high water from Salt Creek, and numerous county roads were impassible throughout Osage County.  An EF-1 tornado also occurred in Osage County approximately near Fairfax (see below for tornado survery information).

A third round of nocturnal thunderstorms affected locations along the Oklahoma-Kansas state line from the evening of the 30th to the early morning hours of May 1st.  This round of storms brought an additional 2”-6” of rain to northern Nowata and northern Craig Counties (and extended further north into southeast KS). These high amounts combined with the antecedent rainfall from the past two nights, led to more flash flooding and exacerbated the ongoing river flooding.  The greatest flooding impact for this last round of rain occurred across Nowata and Craig Counties, with reports of flooded homes in South Coffeyville and in Welch.  Media reports indicated around 17 people were rescued by boat from flooded homes on the west side of Welch.  Numerous roads throughout these counties were closed, including State Highway 10 near Lenapah (due to the Verdigris River).  In addition to the flooding, wind damage and tornadoes occurred.  A supercell thunderstorm produced several brief tornadoes during the late evening hours as it moved slowly across Nowata County and at least two tornadoes developed along the leading edge of a line of storms that moved through the region after midnight. See below for details regarding these tornadoes.

Widespread 5”-6” of rain fell across the Verdigris River basin upstream of Lenapah, with areas of over 7” in the upper reaches through the morning of the 30th.   After the additional rainfall April 30-May 1, widespread storm total rainfall of 6”-10” with an isolated 12” occurred over the Verdigris River basin upstream of Lenapah.   This has caused a signigicant rise along the Verdigris River near Lenapah, and Major flooding is possible.   Moderate flooding is expected along the Neosho River near Commerce due to widespread 3” and isolated areas of over 5” of rain across the basin in southeast KS through the morning of the 30th plus the additional widespread 3”-5” with isolated 7” from the last round of storms.   Additional river flooding in anticipated along the Caney River near Collinsville and along the Neosho River near Quapaw.

Information from this event is still considered preliminary and will be modified based on additional information that may become available to us.  Anyone with information that could enhance the record of this event should contact the National Weather Service Office in Tulsa at 918-838-7838 during business hours, or send us an email at sr-tsa.stormreport@noaa.gov, or submit an online report.

 Image captions below the image.  Click on image to open a larger version in a new window.

OK rainfall map OK rainfall map
24-hour rainfall map ending 7 am CDT April 29, 2012
24-hour rainfall map ending 7 am CDT April 30, 2012
 rainfall total radar estimated rainfall
24-hour rainfall map ending 7 am CDT May 1, 2012 3-Day Storm Total Rainfall ending 7am CDT May 1, 2012
 storm total rainfall 
  3-Day Storm Total Rainfall ending 8am CDT May 1, 2012 (zoomed in to northeast OK/southeast KS)

 Image captions below the image.  Click on image to open a larger version in a new window.

flooded road water vapor image Verdigris River flooding
Water flowing over a road near Burbank, OK in Osage County (Photo: American Red Cross) Flooding in Burbank, OK in Osage County (Photo: KOTV viewer) The Verdigris River flowing over SH 10 near Lenapah, OK (Photo: NWS Tulsa)
Roof removed Welch home damage Welch mobile homes Delaware
North facing side of house blown out. House also shifted slightly off foundation. (Photo: NWS Tulsa) The roof of this permanent home near Welch was removed by an EF-2 tornado. (Photo: NWS Tulsa) Destroyed mobile homes near Delaware. (Photo: NWS Tulsa)
mobile homes Delaware Verdigris River near Lenapah  Neosho River near Commerce 
Destroyed detached garage near Delaware. (Photo: NWS Tulsa)  Preliminary crest hydrograph for the Verdigris River near Lenapah (not a current image) Preliminary crest hydrograph for the Neosho River near Commerce (not a current image)

Tornado Survey Information:

Fairfax, OK (Osage County) Tornado

EF-1 with estimated peak wind of 90 mph
Began: 8:57pm CDT April 29, 2012, 7 miles east of Fairfax
Ended: 8:59pm CDT April 29, 2012, 13.6 miles southwest of Pawhuska
Path length: 1.3 miles      Path width: 220 yards
Summary: The tornado damaged oak trees and 4 power poles near Bill Morris Road east of Fairfax.  The tornado path may well have been longer but few public roads exist in the area, making it impossible to survey all the areas where tornado damge could have occurred. 

 

Dewey, OK area (Osage County) possible Tornado

The NWS survey team could not access the most likely location for tornado damage west of Dewey near Lake Hudson.  The team found tree damage near the Lake Hudson Dam, but not a defined path.  A chaser may have filmed a brief tornado in this area.  A final determination is pending a review of the video, radar data, and the tree damage pattern.

 

Curl Creek, OK (Nowata County) Tornado

EF-1 with estimated peak wind of 105-115 mph
Began: 12:42 am CDT May 1, 2012, 8 miles west-southwest of Nowata
Ended: 12:48 am CDT May 1, 2012, 6.5 miles northwest of Nowata
Path length: 6.5 miles        Maximum path width: 300 yards
Summary: This tornado snapped or uprooted numerous hardwood trees in its path and damaged a large barn.

 

Welch, OK (Craig County) Tornado

EF-2 with estimated peak wind of 110-120 mph
Began: 1:30 am CDT May 1, 2012, 1 mile north of Welch
Ended: 1:32 am CDT May 1, 2012, 1.8 miles northeast of Welch
Path length: 1 mile       Maximum path width: 150 yards
Summary: This tornado tore the roof off of a permanent home, shifted another home off its foundation, and blew out an exterior wall, turned over an outbuilding, rolled two horse trailers, destroyed a 40 foot by 60 foot steel framed barn, and snapped or uprooted trees.  A person was injured in one of the permanent homes when the window in her bedroom shattered.

 

Childers, OK (Nowata County) Tornado

EF-1 with estimated peak wind of 95-105 mph
Began: 8:59 pm CDT April 30, 2012, 2.3 mile northeast of Childers
Ended: 9:03 pm CDT April 30, 2012, 3.8 miles northeast of Childers
Path length: 1.5 mile       Maximum path width: 200 yards
Summary: The tornado snapped the trunks of a few hardwood trees, snapped limbs off of trees, and blew part of the roof off of a 40 foot by 40 foot pole barn.

 

Other Tornados

Storm spotters reported several brief tornado touchdowns about 4 miles west of Nowata in Nowata County between 8:10 and 8:15 pm April 30.  Some tree damage was found by the survey team in this general area on and south of Highway 60 west of town.

Another brief tornado was reported by a storm spotter about 4 miles northwest of Nowata in Nowata County at about 8:25 pm April 30. The survey team found no damage in this area, but there was a lot of open country in the area this tornado likely occurred.

Another area of interest that the survey team looked at was in and near the town of Delaware in Nowata County.  At about 12:55 am May 1, two mobile homes were destroyed in town and one of the three people in the homes at the time was seriously injured.  Large tree limbs were blown down, power poles were snapped, and a third mobile home received roof damage.  Right now this appears to be the result of straight line wind associated with a bowing line segment.

 

 

Preliminary Event Impact Map This map will be updated as additional information is received.  Click on the icons within the map for additional details and/or images related to that impact.  Tornado information can be found by clicking on the track.

Tornado Tracks: Due to mapping/GPS software differences and road accessibility along the track, use the plotted tracks for general reference only. Tornado tracks may be updated and/or changed due to storm damage surveys, data analysis, and eyewitness reports.

Storm Survey: Colored icons represent the Storm Survey rating assigned to surveyed damage. Click on the icon for additional information and available photos. You may need to zoom in tightly to see all the available data points when data points are logged close to one another.  Links to photos are available in the upper portion of the text window that opens when you click on one of the colored data icons or points.

Hail, Wind, and Flood Reports: Click on the icon for the time, location, and description of the storm report. Click here to submit your storm report.

Other Data: Additional data or images from the event.

Survey Legend

 

 

 


 

 

 
 
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