|
August 2019 & Summer 2019
|
|
|
|
|
|
|
|
- A new record August rainfall of 11.70” was set in Fort Smith, AR, surpassing the previous record of 10.89” in 1890.
|
|
|
|
|
|
|
- Using the radar-derived estimated observed precipitation from the RFCs, rainfall totals for August 2019 ranged from 0.50” to near 17” across eastern OK and northwest AR. A large portion of the HSA received 5”-8” of rain this month, with several areas seeing 10”-15”. A smaller portion of Choctaw and southern Pushmataha Counties only had 0.50” to 1.5”. These rainfall totals correspond to 150%-500% of the normal August rainfall in eastern OK and northwest AR generally north of a McAlester to Poteau line. South of this line in southeast OK, the rainfall corresponds to generally 25%-90% of the normal August rainfall.
|
- Several rounds of heavy rain resulted in flash flooding this month.
|
- According to the Drought Monitor from August 27, 2019, Moderate (D1) Drought had developed over portions of Pushmataha and Choctaw Counties. Abnormally dry, but not in drought, conditions (D0) were present in portions of Latimer, Le Flore, Pushmataha, and Choctaw Counties. The remainder of eastern OK and northwest AR was drought free.
|
- According to the Oklahoma Climatological Survey, the 30-day period August 2-31, 2018 was the 23rd wettest for northeast Oklahoma, the 21st wettest for east central Oklahoma, and the 10th wettest for southeast Oklahoma. Records go back to 1921. For Summer 2018 (June-July-August), northeast Oklahoma ranked as the 44th driest, east central Oklahoma was the 37th wettest, and southeast Oklahoma was the 27th wettest period. For the Water Year-to-date, October 1, 2017-August 31, 2018, northeast Oklahoma ranked as the 34th driest, east central Oklahoma was the 40th wettest, and southeast Oklahoma was the 47th wettest period.
|
- Through the morning hours of the 1st, showers and thunderstorms moved south out of southeast KS into far northeast OK and northwest AR, where around 0.25” to around 1.5” of rain fell. However, higher totals of 1.5” to near 6” of rain fell over far eastern KS (Fig. 4), affecting the Neosho River basin. This water resulted in minor flooding along the Neosho River near Commerce.
|
- Early in the morning of the 2nd, a band of showers and thunderstorms developed across eastern KS as a result of isentropic lift within a very moist airmass. This band continued to develop southward into north central/northeast OK through the morning hours, producing heavy rain across eastern Kay, western Osage, Pawnee, and western Creek Counties. This activity weakened through the mid- to late-morning hours as it spread eastward. Light rain continued through the afternoon before mostly dissipating by mid-evening. Just before midnight, thunderstorms developed again west of Highway 75 within a zone of isentropic lift to the north and east of a surface frontal boundary as an upper-level disturbance embedded within the north-northwest flow aloft moved into the region. This activity then dissipated around noon on the 3rd. Meanwhile, new showers and thunderstorms developed further east across far eastern OK and northwest AR in another zone of isentropic lift. These scattered showers and thunderstorms continued through the afternoon hours and dissipated by mid-evening. By 7am CDT 8/03/2019, 1”-4” of rain had fallen across eastern Kay, western Osage, Pawnee, and Creek Counties, and an additional 1”-5” fell between 7am and noon. The scattered showers and thunderstorms produced isolated areas of 1.5”-3”.
|
- Several rounds of rain affected the Neosho River basin in southeast KS during the afternoon and evening hours on the 7th. A line of showers and thunderstorms developed along an outflow boundary from this activity over northwest AR and adjacent OK counties during the afternoon hours. Later that night, new convection developed over southeast KS and continued to develop south into northeast OK and northwest AR around midnight. These thunderstorms continued through the early to mid-morning hours, generally along and north of Highway 412. By 7 am on the 8th, rainfall totals across far northeast OK and northwest AR were 0.25” to around 3”. Moderate flooding occurred along the Neosho River near Commerce from this rainfall. This rainfall also resulted in rises along the Verdigris River near Lenapah, though the river crested just below flood stage.
|
- As a surface boundary sagged south, more showers and thunderstorms developed along it from southwest OK to northeast OK. The southern portion of this line died out by noon, with showers and thunderstorms continuing across northeast OK and northwest AR through the afternoon. Convection renewed along the boundary from southeast OK into northwest AR mid-evening. As the front stalled out, more convection developed near it, from Ponca City, OK to Ozark, AR, after midnight on the 9th as another upper-level wave interacted with a low-level jet and warm air advection near the front. By 7 am on the 9th, rainfall totals ranged from a few hundredths to near 6”, with the heaviest widespread rainfall over Washington, Crawford, and Franklin Counties in west central AR. This rainfall resulted in a quick rise along the Mulberry River near Mulberry, though the river remained just below flood stage. Flash flooding was reported in Mountainburg, AR (Crawford County), where multiple homes were flooded (up to 14” of water in some), water rescues were required, several roads were closed, and a bridge was washed out. Other parts of Crawford County, as well as areas of Franklin County, reported numerous road closures due to flash flooding. Bands of elevated showers and thunderstorms continued through the morning across eastern OK and northwest AR within a convergent zone of the low-level jet. Precipitable water values were over 2”, resulting in additional heavy rainfall from the strongest of the storms. Most of the rain came to an end by early afternoon. Shortly after midnight on the 10th, showers and thunderstorms once again developed across northeast OK and northwest AR, continuing through the mid-morning hours before dissipating or moving out of the area. Rainfall totals by 7 am on the 10th ranged from around one tenth of an inch to around 5”.
|
- The 7-day rainfall total ending on the morning of August 12 was a widespread 2”-4” and localized areas of 4”-6” from west central AR, through northeast OK, and into southeast KS. The 14-day rainfall was widespread 2”-5” with several pockets of 5”-10”. Rainfall over the mid- to upper-Neosho River basin on the 10th-12th resulted in another minor flood along the Neosho River near Commerce as the flood wave moved downstream.
|
- Showers and thunderstorms developed during the early morning hours of the 16th along an outflow boundary across far southeast KS and northeast OK, and then continued through the morning and early afternoon hours across northeast OK and northwest AR. Isolated thunderstorms redeveloped across far northeast OK during the heat of the afternoon, then dissipated by mid-evening. Rainfall was generally around 0.25” to around 1”, though there were isolated areas of 1” to around 1.5” of rain. Around sunrise on the 17th, showers and thunderstorms moved south out of southeast KS into northeast OK. Scattered convection continued across northeast OK through the morning and afternoon hours. A thunderstorm complex moved across KS after midnight on the 18th, and crossed into far northeast OK in the predawn hours. Most of the activity on the 17th-18th occurred across the counties that border the OK/KS state line, bringing a total of 0.50”-2.5” of rain by 7 am on the 18th. The multiple rounds of rainfall over the lower portion of the Neosho River basin led to the river rising to within a few inches of flood stage near Commerce on the 18th.
|
- Scattered showers and thunderstorms developed over the area during the heat of the afternoon on the 21st and then dissipated with the loss of heating by late evening. A change in the weather pattern from high heat and humidity to a more unsettled pattern began on the 22nd, as a surface boundary sagged into the region and became nearly stationary. A series of mid-level shortwaves, embedded within west-northwest flow aloft, interacted with the boundary, resulting in numerous rounds of rain through the 27th. The first round of rain occurred around midnight on the 22nd along the OK/KS border, driven by outflow from southern KS storms. This activity continued through the morning hours across northeast OK and northwest AR. Rainfall totals ranged from 0.10” to 4”, with widespread 1”-3” near the OK/KS state line.
|
- During the late afternoon of the 22nd, thunderstorms developed from east central OK into northwest AR. These storms continued across far east central OK and west central AR through the evening. Meanwhile, a cluster of thunderstorms over central OK moved northeast into northeast OK and far northwest AR during the evening. Convection continued to develop after midnight on the 23rd, covering much of east central and northeast OK and northwest and west central AR, as considerable transport of moisture (precipitable water values of 1.5”-2”) interacted with a quasi-stationary surface boundary just south of I-40. Far east central OK and west central AR received heavy rain for many hours before the storms dissipated around noon. By 7 am on the 23rd, widespread 1.5” to 4” of rain had fallen across northeast and east central OK and northwest and west central AR, with the heaviest rainfall of 3”-8” occurring along the Arkansas River Valley.
|
- After only a short break from the rain, showers and thunderstorms once again developed near the I-40 corridor, in response to a left-over mesoscale convective vortex (MCV), shortly after midnight on the 24th and continued until shortly after noon. Additional heavy rain fell across the same region that was recently saturated, causing additional flash flooding and, unfortunately, a fatality when a 47-year old woman delivering newspapers in Fort Smith, AR drove into water over a road early on the 24th. Sebastian County Emergency Management reported 64 homes experienced flooding (38 in Fort Smith, 19 in Lavaca, and 7 in Barling) from all of this rainfall. 24-hour rainfall totals by 7 am on the 24th ranged from 0.50” to around 3”, with much higher totals of 3”-8”across southern Crawford, northern Sebastian, and southwestern Franklin Counties. An additional 0.75”-3” of rain fell after 7 am through around noon.
|
- A weakening thunderstorm complex moved southeast into the area around sunrise on the 25th. A line of scattered showers and thunderstorms moved through most of eastern OK and northwest AR by mid-afternoon. Locations generally along and north of Highway 412 received widespread 0.25” to around 2” of rain, with scattered totals of around 0.75” or less elsewhere. Through the morning of the 26th, the 7-day rainfall total ranged from 2”-12” across all of eastern OK and northwest AR, except for far southeast OK, which only received around 1” or less. The heaviest rainfall of 8”-12” in 7 days was across Sequoyah, northern Le Flore, Crawford, and Sebastian Counties. 5”-8” fell in parts of Osage, Creek, Tulsa, Okmulgee, Haskell, and Franklin Counties as well.
|
- An advancing cold front encountered a very unstable airmass as it moved into northeast OK and northwest AR on the evening of the 26th. A line of scattered thunderstorms quickly developed north of I-44 mid-evening and progressed southeast through the overnight hours. The last of the rain moved south of the Red River into TX by mid-morning on the 27th. Despite a faster storm movement with this activity, high rain rates occurred due to precipitable water values near 2”. Much of far eastern OK received 1”-2.5” of rain, with localized amounts of 2.5” to 4”. Across western AR, totals were 0.25” to near 1”.
|
- In the pre-dawn hours of the 30th, a line of thunderstorms moved out of KS into north central and northeast OK, continuing to the southeast across all of eastern OK and northwest AR through mid-morning hours. Some showers lingered through the afternoon across southeast OK. Rainfall totals were around 0.50” to around 1.5” for most of the area.
|
| Summer (June-July-August) 2019 |
|
|
|
|
|
|
|
Follow us on Twitter
Follow us on Facebook
Follow us on YouTube
TSA RSS Feed