While it heated up, it was not dry everywhere on the 15th. Before the ridge of high pressure could get here, a stationary front was in place across northeast sections of the state. Surrounding the front, scattered thunderstorms popped up during the afternoon. Some of the storms became strong to severe.
Mainly hail occurred with the strongest storms. The largest stones were about the size of a lime (two inches in diameter), and were reported just southwest of Salado (Independence County) at 711 pm CDT. Quarter to golf ball size hail was produced at  few miles west of Pocahontas (Randolph County), north of Huff, southwest of Batesville, and at Cushman (all in Independence County).
A few days later (on the 18th), a powerful storm system went from the southern Plains to the upper Midwest, with a cold front dragged into the region by the system. As the day began, storms were ongoing from Texas into Oklahoma. A line of storms eventually made it into western Arkansas by 200 pm CDT.
Just like on the 1st, part of the line bowed out (indicating the presence of strong to damaging winds) from Fort Smith (Sebastian County) to Clarksville (Johnson County). There was extensive tree damage, with trees on houses and blocking roads. Hardest hit areas inlcuded Paris and Scranton (both in Logan County). Gusts likely exceeded 90 mph.
Along the way, several photos showed a lot of dust kicked up by the wind. Gustnadoes or dust devils were also generated as the wind speed rapidly increased. There was a weak tornado (rated EF0) produced three miles west of Slovak (Prairie County). A couple of grain bins were dented or pushed in.

Hail in JACKSON, ARKANSAS
From 15-MAY-19 15:40:00 to 15-MAY-19 15:40:00 (CST-6)
Location: DIAZ
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Thunderstorm Wind in HOT SPRING, ARKANSAS
From 18-MAY-19 15:06:00 to 18-MAY-19 15:06:00 (CST-6)
Location: DUFFIE
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Multiple trees were reported down south of Bismarck.

Hail in ARKANSAS, ARKANSAS
From 15-MAY-19 16:04:00 to 15-MAY-19 16:04:00 (CST-6)
Location: LORINE
Magnitude: 1.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

This was reported via Twitter.

Thunderstorm Wind in HOT SPRING, ARKANSAS
From 18-MAY-19 15:12:00 to 18-MAY-19 15:12:00 (CST-6)
Location: BISMARCK
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Power lines were blown down across Highway 7 near Bismarck.

Hail in JACKSON, ARKANSAS
From 15-MAY-19 17:05:00 to 15-MAY-19 17:05:00 (CST-6)
Location: POSSUM GRAPE
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Hail size was estimated from a video posted online.

Thunderstorm Wind in PULASKI, ARKANSAS
From 18-MAY-19 16:06:00 to 18-MAY-19 16:06:00 (CST-6)
Location: CYPRESS JCT
Magnitude: 61.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Social Media

The Cimarron Inn on Frontage Rd. sustained roof damage.

Thunderstorm Wind in LOGAN, ARKANSAS
From 18-MAY-19 13:33:00 to 18-MAY-19 13:42:00 (CST-6)
Location: PARIS
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous trees were downed from Paris to north of Subiaco toward Morrison Bluff.

Hail in INDEPENDENCE, ARKANSAS
From 15-MAY-19 17:18:00 to 15-MAY-19 17:18:00 (CST-6)
Location: SALADO
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Thunderstorm Wind in PULASKI, ARKANSAS
From 18-MAY-19 16:10:00 to 18-MAY-19 16:10:00 (CST-6)
Location: CYPRESS JCT
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A tree was down off of Hinkson Rd.

Hail in INDEPENDENCE, ARKANSAS
From 15-MAY-19 17:50:00 to 15-MAY-19 17:50:00 (CST-6)
Location: COLLIETOWN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Thunderstorm Wind in LONOKE, ARKANSAS
From 18-MAY-19 16:54:00 to 18-MAY-19 16:54:00 (CST-6)
Location: BLAKEMORE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Limbs and trees were reported down near Blakemore.

Thunderstorm Wind in LOGAN, ARKANSAS
From 18-MAY-19 13:33:00 to 18-MAY-19 13:33:00 (CST-6)
Location: PARIS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous trees were down in the town of Paris.

Thunderstorm Wind in LONOKE, ARKANSAS
From 18-MAY-19 16:30:00 to 18-MAY-19 16:30:00 (CST-6)
Location: TOLTEC
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A large tree was blown over and blocking Stewart Rd.

Tornado in PRAIRIE, ARKANSAS
From 18-MAY-19 16:55:00 to 18-MAY-19 16:56:00 (CST-6)
Location: SLOVAK
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A weak EF0 tornado was confirmed near Slovak from thunderstorms that occurred Saturday evening. Damage was minimal as the tornado remained over mostly farmland.

Thunderstorm Wind in LOGAN, ARKANSAS
From 18-MAY-19 13:35:00 to 18-MAY-19 13:35:00 (CST-6)
Location: PARIS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A large tree was uprooted.

Thunderstorm Wind in LONOKE, ARKANSAS
From 18-MAY-19 16:34:00 to 18-MAY-19 16:34:00 (CST-6)
Location: PETTUS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

A 60 mph wind gust was estimated near the intersection of Hwy. 31 and Simpson Rd. in southern Lonoke County.

Thunderstorm Wind in LOGAN, ARKANSAS
From 18-MAY-19 13:40:00 to 18-MAY-19 13:40:00 (CST-6)
Location: WILKINS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

A gust of 60 mph was estimated from a thunderstorm.

Thunderstorm Wind in LONOKE, ARKANSAS
From 18-MAY-19 16:36:00 to 18-MAY-19 16:36:00 (CST-6)
Location: PETTUS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A large tree was down along Hwy. 31 at Simpson Rd.

Thunderstorm Wind in JOHNSON, ARKANSAS
From 18-MAY-19 13:41:00 to 18-MAY-19 13:41:00 (CST-6)
Location: COAL HILL
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Trees were down along Main Street in Coal Hill.

Thunderstorm Wind in LONOKE, ARKANSAS
From 18-MAY-19 16:36:00 to 18-MAY-19 16:36:00 (CST-6)
Location: SOUTH BEND
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

A tree was down on a house on Bowen Rd. near Furlow.

Thunderstorm Wind in LOGAN, ARKANSAS
From 18-MAY-19 13:41:00 to 18-MAY-19 13:41:00 (CST-6)
Location: KALAMAZOO
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous trees were down north of Subiaco in the Patterson Bluff Area. The time is estimated from radar.

Thunderstorm Wind in INDEPENDENCE, ARKANSAS
From 18-MAY-19 16:37:00 to 18-MAY-19 16:37:00 (CST-6)
Location: GRAY
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A tree fell on a barn. Trees were also uprooted.

Hail in INDEPENDENCE, ARKANSAS
From 15-MAY-19 18:10:00 to 15-MAY-19 18:10:00 (CST-6)
Location: BATESVILLE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Thunderstorm Wind in LOGAN, ARKANSAS
From 18-MAY-19 13:45:00 to 18-MAY-19 13:45:00 (CST-6)
Location: SCRANTON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

A thunderstorm wind gust was estimated at 60 mph.

Thunderstorm Wind in LONOKE, ARKANSAS
From 18-MAY-19 16:42:00 to 18-MAY-19 16:42:00 (CST-6)
Location: PETTUS
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Minor structural damage was reported at Caney Creek Baptist Church along Hwy. 31 near Laster Rd.

Hail in INDEPENDENCE, ARKANSAS
From 15-MAY-19 18:11:00 to 15-MAY-19 18:11:00 (CST-6)
Location: SOUTHSIDE
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Thunderstorm Wind in JOHNSON, ARKANSAS
From 18-MAY-19 13:52:00 to 18-MAY-19 13:52:00 (CST-6)
Location: CLARKSVILLE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

The top half of a tree was reported to have fallen on a house.

Thunderstorm Wind in LONOKE, ARKANSAS
From 18-MAY-19 16:48:00 to 18-MAY-19 16:48:00 (CST-6)
Location: CULLER
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Powerlines were down near the intersection of Hwy. 381 and Hillman Rd.

Hail in INDEPENDENCE, ARKANSAS
From 15-MAY-19 18:18:00 to 15-MAY-19 18:18:00 (CST-6)
Location: SOUTHSIDE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Thunderstorm Wind in JOHNSON, ARKANSAS
From 18-MAY-19 13:54:00 to 18-MAY-19 13:54:00 (CST-6)
Location: CLARKSVILLE
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Limbs were reported down in the city of Clarksville.

Thunderstorm Wind in LOGAN, ARKANSAS
From 18-MAY-19 13:35:00 to 18-MAY-19 13:35:00 (CST-6)
Location: PARIS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Several trees were down as a result of wind gusts to 60 mph.

Thunderstorm Wind in PULASKI, ARKANSAS
From 18-MAY-19 16:10:00 to 18-MAY-19 16:10:00 (CST-6)
Location: CYPRESS JCT
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A tree was blown down across Baseline Rd. All lanes were temporarily blocked.

Thunderstorm Wind in CALHOUN, ARKANSAS
From 18-MAY-19 16:15:00 to 18-MAY-19 16:15:00 (CST-6)
Location: HARLOW
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Trees were reported blown down.

Thunderstorm Wind in DALLAS, ARKANSAS
From 18-MAY-19 17:13:00 to 18-MAY-19 17:13:00 (CST-6)
Location: DALARK
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Trees were down across Hwy. 7 and all lanes were temporarily blocked.

Thunderstorm Wind in BOONE, ARKANSAS
From 18-MAY-19 14:36:00 to 18-MAY-19 14:36:00 (CST-6)
Location: HARRISON
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Trees were reported blown down around Harrison.

Thunderstorm Wind in ARKANSAS, ARKANSAS
From 18-MAY-19 17:24:00 to 18-MAY-19 17:24:00 (CST-6)
Location: ONA
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Winds were estimated at 70 mph.