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May 2019 & Spring 2019
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- Fort Smith: No daily records were set or tied this month.
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- Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for May 2019 ranged from 3” to 25” across eastern OK and northwest AR. A rainfall minimum stretched from Pittsburg County to Carroll County, where 3”-6” of rain fell. To the southeast of this corridor, rainfall totals were widespread 6” to around 10”, while northeast of this corridor, rainfall was a widespread 8”-20” with isolated pockets of 20”-25”. These rainfall totals correspond to 200%-400% of the normal May rainfall across northeast OK, along and northwest of I-44. Southeast of a McAlester to Springdale line, the rainfall totals correspond to 75% to around 150% of the normal May rainfall.
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- Tornado statistics for NWS Tulsa area of responsibility in eastern OK and northwest AR only:
- May 2019 had 48 total tornadoes. This sets the record for most tornadoes in the month of May. The previous record was 39 tornadoes in 2010. This also sets the record for most tornadoes of any month. The previous record was 42 tornadoes in April 2011.
- 41 tornadoes during the 7-day period May 18 – 22, 2019. This sets the record for most tornadoes during a 7-day period. The previous record was 35 tornadoes May 10 - 16, 2010.
- 38 tornadoes during the 7-day period of May 20 - 26, 2019. Now the 2nd most tornadoes in a 7-day period.
- 61 tornadoes Jan. 1-May 31, 2019 ranks as 2nd most for the entire year. The record is 77 tornadoes in 2011.
- During a 48-hour period, starting with the first tornado on 20:05 May 20th through 19:52 on the 22nd of May, a total of 28 tornadoes occurred over a period of 47 hours and 47 minutes. This sets the record for tornadoes in a 48-hr period. The previous record was 25 tornadoes on the 14th of April 2011.
- 20 tornadoes occurred on May 22nd over a period of 8 hours and 14 minutes. This is the 4th most tornadoes within a 24-hr period. (Timing was determined using the start time of the first tornado as the starting time of the time period, and the start time of the last tornado as the ending time of the time period.
- More info at: https://arcg.is/1X8eW1
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- Very heavy rainfall in northern OK/southern KS, in excess of 15”, resulted in Major and Record flooding for numerous rivers this month. There were 31 crests above the Major flood category at 17 river forecast points in the NWS Tulsa HSA. Three of these points, the Arkansas River near Ponca City, the Arkansas River at Van Buren, and Bird Creek at Avant, exceeded their record stages. Numerous river forecast points were above flood stage for a week or more, with a handful remaining above flood stage for more than 2 weeks. Three different flood events during the 37-day period from May 1-June 6 along the Neosho River resulted in the forecast point near Commerce being above flood stage for a total of 28 days and approximately 9 hours. In total, 29 of the 34 river forecast points in the NWS Tulsa HSA exceeded flood stage during May 2019. The confluence of three large river basins, the Upper Arkansas, Verdigris, and Neosho basins, all of which received the heaviest rainfall this month, occurs near Muskogee, OK, where very severe flooding occurred as the three rivers merged into the Arkansas River. The major flooding then continued downstream along the Arkansas River through east central Oklahoma and west central Arkansas, despite the lower rainfall totals directly over this region. Backwater flooding also occurred along the tributaries of the larger rivers. Based on information from the U.S. Army Corps of Engineers (USACE) Tulsa District, 11 reservoirs in the Arkansas, Verdigris, and Neosho River basins set new record pool levels, 6 of which are within the NWS Tulsa HSA. In addition to the significant flood event, a record number of tornadoes occurred in the NWS Tulsa area this month. A Federal Major Disaster Declaration was made in OK (DR-4438) and AR (DR-4441).
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- The NWS Hydrometeorological Design Studies Center (HDSC) analysis shows that the Annual Exceedance Probability for the 30-day rainfall total (https://www.nws.noaa.gov/oh/hdsc/aep_storm_analysis/) between April 29 and May 30, 2019 was 1/200 to 1/1000 for parts of the NWS HSA (in other words: 0.5% to 0.1% annual chance of occurrence, or between a 200-yr and 1000-yr rainfall event). A portion of south central Kansas had <1/1000 annual exceedance probability (<0.1%, or greater than a 1000-year rainfall event)! This rare rainfall event occurred in the upper Arkansas, Verdigris, and Neosho River basins and ultimately resulted in major flooding along area rivers. (Note: rainfall recurrence intervals do not equal flood recurrence intervals – i.e. a 100-year rainfall event does not equal a 100-year flood event).
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- A line of showers and thunderstorms near a surface boundary moved across north central and northeast OK in the pre-dawn hours of April 30th. As this activity moved north into KS at mid-morning, another line of showers and thunderstorms from central OK spread northeast into northeast OK along the front as it slowly moved south. Additional thunderstorms developed near, as well as ahead of the front in the warm sector, during the afternoon. Several of these storms became severe, with moisture and shear parameters supportive of rotating supercells. 13 tornadoes (ranging from EF-0 to EF-2) occurred across eastern OK (see https://arcg.is/1X8eW1 for more information). On the synoptic scale, southwest deep-layer flow (parallel to the front) and a high precipitable water (near 2”) airmass supported repeated rounds of training thunderstorms, which resulted in heavy rain and flooding. By early evening, thunderstorms congealed into a line across northeast OK, spread east through the evening, and produced very heavy rainfall. Widespread showers and thunderstorms continued behind the leading line, covering all of eastern OK and northwest AR by late evening. As this area of rain pushed east of the region in the very early morning hours, yet another area of showers and thunderstorms developed over southeast OK and moved northeast, and a line of thunderstorms over central OK moved east as a squall line. All of this activity brought additional rainfall to a large portion of eastern OK and northwest AR. The rain finally came to an end by mid-morning on May 1. Most of eastern OK and northwest AR received 2”-3” of rain from this event, with higher totals of 4”-6.5” in portions of northeast OK and southeast OK. Widespread flash flooding occurred with this heavy rain, and one fatality (pending medical examiner’s report) occurred in Tulsa, OK when a motorist left the highway, drove into a swollen drainage ditch, and was washed downstream. The official observing site in Tulsa, OK recorded 3.15” of rain on April 30, most of which fell in a few hours, setting a new daily rainfall record for that day (previous record was 3.00” in 1970). Additionally, all of the water resulted in significant rises along area creeks and rivers, and minor to moderate river flooding along the Polecat Creek near Sapulpa, Bird Creek near Sperry, Caney River near Collinsville, Verdigris River near Lenapah, Illinois River near Watts, Chewey, and Tahlequah, Poteau River near Poteau and Panama, Neosho River near Commerce, Spring River near Quapaw, and the Kiamichi River near Antlers.
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- Showers and thunderstorms move east out of south central OK into southeast OK and west central AR, primarily along and south of I-40, during the evening of May 2nd. This activity continued through the overnight hours and spread a little north into northwest AR. Rainfall totals ranged from 1” to around 3” along and south of a McAlester to Ozark line, with lesser amounts further north from McAlester to Springdale.
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- A thunderstorm complex ahead of a cold front moved out of south central KS/central OK and into northeast OK around noon on the 3rd. This widespread activity progressed east across eastern OK and northwest AR, primarily north of I-40, through the afternoon and early evening hours. The showers and thunderstorms were more scattered further south across southeast OK. Widespread rainfall totals of around 0.50” to around 1” occurred along and north of I-40, with localized pockets of 1.5” to 3” of rain.
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- Thunderstorms again developed along a cold front in western KS and along a dryline in western OK on the 5th, and this activity then moved into eastern OK by the late evening. These storms moved eastward across all of the HSA, except far southeast OK, through the overnight hours and early morning hours of the 6th. Locations primarily north of Highway 412 in northeast OK and northwest AR received 0.50” to around 2” of rain, with localized amounts around 3” in Osage and Pawnee Counties. It should also be noted that the heavier rainfall also occurred on the upper Arkansas River basin upstream of the NWS Tulsa HSA. This will eventually play a role later in the month. This additional rainfall, combined with the rainfall from the end of April and through the first few days of May, resulted in higher river and lake levels across northeast OK. By this time, the Arkansas River near Muskogee was holding nearly steady just below flood stage as upstream water was released to lower flood control pools from area reservoirs.
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- Heavy rain once again fell across southeast KS as two rounds of heavy rain affected that area during the evening and overnight hours of the 6th-7th. Widespread 1”-4” of rain fell over the Neosho River basin in southeast KS, resulting in moderate flooding along the Neosho River near Commerce.
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- A large thunderstorm complex moved across KS and OK on the 7th and its leading-edge line of storms entered eastern OK at midnight on the 8th. These storms continued eastward through the overnight hours entering western AR near sunrise, and finally pushed east of the HSA by late afternoon. Rainfall totals were around 0.50” to 2” across all of eastern OK and northwest AR, with isolated totals of 2” to 2.5” in western Osage and eastern Kay Counties, and northern Pushmataha and southern Le Flore Counties. Also of note, much higher rainfall totals of widespread 2” to 8” occurred across the upper Arkansas River basin in central OK and central KS. Much of this water also flowed downstream into the Kaw and Keystone reservoirs. The Kaw Lake flood pool was filled, went into surcharge by the evening of May 10th, and fell back to below the top of the flood control pool on the afternoon of the 13th. The Keystone Lake flood pool also rose significantly, but did not fill. The Arkansas River near Ralston exceeded flood stage, remaining just below the moderate flood level from this event. Since the Arkansas River near Muskogee was already near flood stage, flood stage was briefly exceeded a couple of times due to this rainfall event combined with the releases from reservoirs along the Arkansas River and Neosho River basins. Similarly, the Arkansas River at Van Buren also briefly exceeded flood stage due to the already high river levels plus this extra water that routed downstream from Muskogee. This heavy rain also impacted the Deep Fork River, which flowed downstream and led to moderate flooding along the Deep Fork River near Beggs. See the preliminary hydrographs at the end of this report and the E3 Report for details on the river flooding from this event. Other than a few days of scattered showers and thunderstorms, the area remained mostly rain-free through the 17th, helping to lower lake and river levels for many areas. However, the Arkansas River remained slightly below flood stage from Muskogee to Ozark during this time.
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- Heavy Rain and Major Flood Event May 18 – 30, 2019 Summary (Note: maximum elevation, maximum inflow, maximum release, and pool of record data for area lakes are courtesy of the USACE Tulsa District for the period April 29-June 11, 2019 and are still preliminary. Note: river stage data is considered preliminary pending official USGS analysis.):
- A persistent convectively active pattern, consisting of a deep trough over the western U. S. and ridging along the Gulf Coast and southeastern U. S., set the stage for numerous rounds of rainfall across the Southern Plains on the 18th and continuing through the end of the month. The atmospheric moisture, with precipitable water content of 1.5”-2”, remained high during this time frame, resulting in very efficient rainfall-producing showers and thunderstorms. Antecedent conditions from the rainfall earlier this month and at the end of April meant that soil moisture was already high, and any additional rainfall would quickly become runoff. Antecedent river and lake levels were also above normal ahead of this active storm period. 6”-16” inches of rain fell between May 18 and May 30 along and northwest of a line from near Okmulgee, OK to near Bentonville, AR, and 3”-5” inches of rain fell southeast of this line (Fig. 15). Widespread 10”-16” fell in the southern KS and northern OK area bounded by Kingfisher, OK - Tulsa, OK - Miami, OK - Emporia, KS - Wichita, KS (Fig. 16a, b). The result was 34 river floods at 25 river forecast points. There was a total of 62 crests during those 34 floods, 3 which were new records (Arkansas River near Ponca City and at Van Buren, and Bird Creek at Avant), and 31 which were crests in the major flood category. 17 of the 34 floods lasted 7 days or more; 14 lasted 10 days or more; 5 lasted 14 days or more; and 3 lasted 21 days or more (see preliminary hydrographs at the end of this report; see E3 Report for details). The Arkansas River near Muskogee was above flood stage the longest at approximately 22 days and 5 hours and was also above the Major flood category the longest at approximately 13 days and 12 hours. The first river to rise above flood stage during this event (in the NWS Tulsa HSA) did so on the evening of May 20, 2019. The last river to fall below flood stage from this event did so on the afternoon of June 13, 2019. Therefore, there was a river above flood stage in the NWS Tulsa HSA for just under 24 consecutive days. For the USACE Tulsa District flood control reservoirs, 6 set new pools of record in the NWS Tulsa HSA: Kaw, Keystone, Skiatook, Birch, Oologah, and Hudson Lakes.
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- Oklahoma Governor Stitt declared a State of Emergency for all 77 Oklahoma counties on May 24, 2019. This followed the original declaration signed on May 1, 2019 for 52 counties (including: Adair, Cherokee, Choctaw, Craig, Creek, Delaware, Haskell, Latimer, Le Flore, Mayes, McIntosh, Muskogee, Nowata, Okfuskee, Okmulgee, Osage, Ottawa, Pawnee, Pittsburg, Pushmataha, Rogers, Sequoyah, Tulsa, Wagoner, and Washington) and later amended on May 8 to include 14 additional counties (including Kay).
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- Arkansas Governor Hutchinson declared a State of Emergency for Arkansas on May 21, 2019.
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- President Trump approved a Major Disaster Declaration for Oklahoma on June 1, 2019 for the incident period May 7-June 9, 2019. As of July 2, 2019, the following counties were included: Cherokee, Craig, Creek, Delaware, Haskell, Kay, Le Flore, Mayes, Muskogee, Nowata, Okmulgee, Osage, Ottawa, Pawnee, Rogers, Sequoyah, Tulsa, Wagoner, and Washington. President Trump approved a Major Disaster Declaration for Arkansas on June 8, 2019 for the incident period May 21-June 14, 2019. As of July 2, 2019, the following counties were included: Crawford, Sebastian, and Franklin.
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- According to the Drought Monitor from May 28, 2019, no drought or abnormally dry conditions were present across eastern OK and northwest AR.
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- According to the Oklahoma Climatological Survey, the 30 days ending on May 30, 2019 was the 2nd wettest for northeast Oklahoma, the 12th wettest for east central Oklahoma, and the 10th wettest for southeast Oklahoma. Records go back to 1921. For the Year-to-Date period Jan. 1-May 31, 2019, northeast Oklahoma ranked as the Record wettest, east central Oklahoma was the 9th wettest, and southeast Oklahoma was the 16th wettest period. For the last 365 days (June 1, 2018-May 31, 2019), northeast Oklahoma was the 7th wettest, east central Oklahoma was the 13th wettest, and southeast Oklahoma was the 6th wettest.
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| Spring (March-April-May) 2018 |
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