Climate Data
Yearly Reports
Interested in what kind of weather occurred in a recent year? Check out the most memorable events below.
 
Severe Weather/Heavy Rain on May 20-25, 2011
 
The pattern at 100 pm CDT on 05/20/2011. A storm system and associated cold front moved from the Rockies into the Plains heading into late May. The front was unable to penetrate through a ridge of high pressure over the southeast United States and stalled on the 20th.
In the picture: The pattern at 100 pm CDT on 05/20/2011. A storm system ("L") along the Atlantic Coast was departing with cool and dry air. Meanwhile, a ridge of high pressure ("H") was setting up in the southeast United States, with a new storm system ("L") approaching from the Plains. This was bringing Arkansas warmth and moisture, and high precipitable water values over 1.50 inches. Precipitable water, or water vapor contained in a vertical column of at atmosphere, is normally between 1.00" and 1.25" heading into late May.

 

There was more than enough moisture in place, and widespread heavy rain developed in Arkansas. Amounts averaged one to three inches in the northwest half of the state, with locally more than four inches.

 

Twenty four hour amounts through 700 am CDT on the 21st included 4.53 inches at Nimrod Dam (Perry County), 4.33 inches at Perry (Perry County), 4.27 inches at Batesville Lock and Dam (Independence County), 4.20 inches at Washita (Montgomery County) and 4.08 inches at Glenwood (Pike County). Twenty four hour rainfall through 700 am CDT on 05/21/2011.
In the picture: Twenty four hour rainfall through 700 am CDT on 05/21/2011.

 

Twenty Four Hour Rainfall (through 700 am CDT on 05/21/2011)
Site Amount (Inches)
Nimrod Dam (Perry Co) 4.53
Perry (Perry Co) 4.33
Batesville Lock and Dam (Independence Co) 4.27
Washita (Montgomery Co) 4.20
Glenwood (Pike Co) 4.08
Greers Ferry Lake (Cleburne Co) 3.91
DeGray Lake State Park (Hot Spring Co) 3.90
Damascus (Van Buren Co) 3.81
Amity (Clark Co) 3.77
Center Ridge (Conway Co) 3.70
St. Paul (Madison Co) 3.62
Black Rock (Lawrence Co) 3.61
Steprock (White Co) 3.60
Bismarck (Hot Spring Co) 3.55
Wooster (Faulkner County) 3.51
Nashville (Howard Co) 3.50
Deer (Newton Co) 3.48
Bonnerdale (Hot Spring Co) 3.42
Crystal Valley (Pulaski Co) 3.38
Cabot (Lonoke Co) 3.30
Antoine (Pike Co) 3.24

 

Twenty four hour rainfall through 700 am CDT on 05/24/2011. A few days later, there was another deluge in the northwest (in excess of three inches of rain in spots). There was 4.49 inches measured at Fayetteville (Washington County), with 3.07 inches in one hour. Highfill (Benton County) had 3.20 inches. A vehicle was swept into Butler Creek near Gallatin (Benton County). Four people in the vehicle drowned. A man was killed while swimming in the Buffalo National River. The strength of the current swept the man downstream.
In the picture: Twenty four hour rainfall through 700 am CDT on 05/24/2011.

 

Reservoirs in the north and in southern Missouri were full, with releases at Beaver, Bull Shoals, Norfork and Table Rock Dams.

 

Overflowing White River Basin Lakes (05/24/2011)
Location 7 AM Level (ft) Flood Pool
Beaver Lake (NW AR) 1131.3 1130
Bull Shoals (NC AR) 694.3 695
Norfork Lake (NC AR) 578.7 580
Table Rock Lake (SW MO) 931.9 931
Note: "NW" is northwest, "SW" is southwest, and "NC" is north central.

 

Fortuntately, all of this rain did not affect area tributaries (such as the lower White River) much...which were already high/overflowing from excessive precipitation earlier in the month. However, there was enough rain to push May and spring totals to record levels across parts of the region.

 

 

The most violent severe weather was in the upper Midwest, the mid-Mississippi Valley and the central and southern Plains near a front on May 20-22, 2011.
In the picture: The most violent severe weather was in the upper Midwest, the mid-Mississippi Valley and the central and southern Plains near a front on May 20-22, 2011. The graphic is courtesy of the Storm Prediction Center.
 
There were several rounds of severe weather along/near the stalled front. On the 20th, a weak tornado (rated EF0) was spawned just southwest of Malvern (Hot Spring County). Storms were most severe north and west of Arkansas closest to the front. There was widespread destruction in Joplin, MO after a tornado (rated EF5) ripped through the area toward evening on the 22nd.

 

 

The tornado leveled homes and businesses, and killed more than 150 people. The death toll places this tornado as one of the top ten deadliest in U.S. history, and the deadliest in more than 60 years! Considering vast improvements in technology and advanced warning capabilities, this is stunning. St. John's Hospital in Joplin, MO before and following a devastating tornado (rated EF5) on 05/22/2011.
In the picture: St. John's Hospital in Joplin, MO before and following a devastating tornado (rated EF5) on 05/22/2011. Click to enlarge.

 

Top 10 Deadliest Tornadoes in the U.S.
Place Date Fatalities
Tri-State Tornado (MO/IL/IN) Mar 18, 1925 695
Natchez, MS May 6, 1840 317
St. Louis, MO May 27, 1896 255
Tupelo, MS April 5, 1936 216
Gainesville, GA April 6, 1936 203
Woodward, OK April 9, 1947 181
Joplin, MO May 22, 2011 159
Amite, LA/Purvis, MS April 24, 1908 143
New Richmond, WI June 12, 1899 117
Flint, MI June 3, 1953 116
Note: Some of these events (such as the "Tri-State Tornado") may have been a family of tornadoes instead of single tornadoes. However, there are not enough details (a lack of evidence) to change the findings. Most of these events (prior to the 1950s) occurred before the availability of radar and warnings.

 

Risk of severe weather in the twenty four hour period ending at 700 am CDT on 05/25/2011.
The front finally gained some momentum to the southeast as a new storm system dragged the front toward the region on the 24th. The system initiated thunderstorms from Kansas and Oklahoma into northern Texas, and the event evolved into a tornado outbreak.
In the picture: Risk of severe weather in the twenty four hour period ending at 700 am CDT on 05/25/2011. The forecast (made early on 05/24/2011) is courtesy of the Storm Prediction Center.

 

 The WSR-88D (Doppler Weather Radar) showed strong rotation at Denning (Franklin County) at 1211 am CDT on 05/25/2011.
In the picture: The WSR-88D (Doppler Weather Radar) showed strong rotation at Denning (Franklin County) at 1211 am CDT on 05/25/2011.
The circulation at Denning (Franklin County) passed through areas kust southeast of Horsehead Lake (Johnson County) at 1229 am CDT on 05/25/2011.
In the picture: The circulation at Denning (Franklin County) passed through areas kust southeast of Horsehead Lake (Johnson County) at 1229 am CDT on 05/25/2011. A new area of rotation formed near Clarksville (Johnson County), and eventually strengthened as it headed northeast.
 

Storms became more isolated as they approached Arkansas late in the evening. However, a cluster of storms managed to stay together as they raced through Fort Smith (Sebastian County) with damaging winds. Ahead of the line, an isolated storm began to rotate...and spawned a tornado at Denning (Franklin County).

The tornado then tore through areas just north of Coal Hill before striking Harmony and Ozone (all in Johnson County) between 1200 am and 100 am CDT on the 25th. The tornado was on the ground for 46 miles and was rated EF4 (the strongest tornado of 2011 thus far). The tornado claimed 4 lives (3 in Franklin County and 1 in Johnson County).

 

At least three tornadoes (rated EF1 to EF4) were confirmed on 05/25/2011.
In the picture: At least three tornadoes (rated EF1 to EF4) were confirmed on 05/25/2011.
 

Another cranked up around Clarksville (Johnson County) and headed to areas just northwest of Hagarville (Johnson County). This tornado (rated EF3) killed one person in the Strawberry community.

Later in the day, the front surged into the state. There was one more round of severe weather between 200 pm CDT and 800 pm CDT, including isolated tornadoes.

 

How Many Tornadoes?
This event (May 20th through the 25th) featured a total of four (4) tornadoes in the Little Rock County Warning Area. Statewide, there were ten (10) tornadoes...increasing the yearly total to 70 tornadoes.

 

Two homes were damaged by a tornado near Oil Trough (Independence County). Law enforcement reported a brief tornado near Tichnor (Arkansas County), with power lines downed. There was baseball size hail at White Hall (Jefferson County), hen egg size hail at Rison (Cleveland County) and Newark (Independence County), and golfball size hail at Bauxite (Saline County), Cave City (Sharp County) and Tarry (Lincoln County).

Precipitation tended to develop farther south with time on 05/23/2011 as cool thunderstorm outflow advanced from northern into central Arkansas.
In the picture: A tornado was witnessed a few miles southeast of near Oil Trough (Independence County) on 05/25/2011. The photo is courtesy of Heather Chadwick. Click to enlarge.

 

 

There could have been more tornadoes that day. In fact, more tornadoes were expected...but it did not happen. The Storm Prediction Center (in Norman, OK) has done extensive research on the tornado environment, including a desired Lifting Condensation Level (LCL). This is the height at which air parcels become saturated when lifted adiabatically or without heat transfer. It was found that significant tornadoes are less likely with LCLs over 1000 meters, with chances decreasing markedly as LCLs go over 1500 meters (and as air near the ground dries out).

During the afternoon of the 25th, LCLs increased from the south to more than 1000 meters in much of Arkansas (except maybe the far northeast). By comparison, LCLs dropped to less than 700 meters at Springfield, MO on the 22nd (just before the Joplin, MO tornado).

 

Lifting Condensation Levels
Location/Date 7 AM CDT 1 PM CDT 7 PM CDT
North Little Rock, AR (05/25) 636m 1023m 2452m(!)
Springfield, MO (05/22) 1090m 1130m 604m
! - Values jumped after the passage of a cold front and the arrival of drier air.

 

Storm Reports
Preliminary reports of severe weather in the Little Rock County Warning Area on May 25, 2011 (in red).
Submit a storm report.
Mainly hail and isolated tornadoes were reported on May 25th, especially in central and eastern Arkansas. Tornadoes caused extensive damage in Johnson County, and minor damage in Independence County. For a look at some reports, click here.
 
Link of Interest
Plot Reports
In the picture: Preliminary reports of severe weather in the Little Rock County Warning Area on May 25, 2011 (in red).

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