During the afternoon hours of February 10, 2009, a strong, middle and upper storm system moved across the Four Corners region into the central and southern Great Plains.
A moist, low-level air mass streamed northward across Texas and Louisiana into eastern Oklahoma and the Ozarks ahead of the system.
Daytime heating of the moistening boundary layer increased throughout the afternoon across Oklahoma and Texas as cloud cover shifted eastward.
Cooling aloft, in conjunction with the approaching storm system, led to atmospheric instability, resulting in thunderstorms.
A very strong wind field increased with height through the lower troposphere, resulting in a wind shear favorable for rotation in the thunderstorms.

Meteorologists expected large hail stones and damaging winds, and recognized the potential for strong tornadoes as thunderstorms developed from central Oklahoma southward into north-central Texas in the afternoon.
During the night, a cold front moved eastward toward the Mississippi Valley and organized the thunderstorms into a lengthy squall line.
Along with a continued threat of hail and tornadoes, the risk of damaging winds increased.
The Storm Prediction Center announced a "moderate risk" of severe weather for portions of eastern Oklahoma, northeastern Texas, western Arkansas, and northwestern Louisiana.

At around 1:00 pm CST (19:00 UTC), a line of violent thunderstorms began developing near the Wichita Mountains in Comanche County, Oklahoma.
The supercell that eventually produced the first tornado of the outbreak moved northeast through Caddo and Grady counties over the next 30 to 45 minutes, before reaching southeastern Canadian County at around 2:00 pm CST (20:00 UTC).
By 2:14 pm CST (20:14 UTC), the line had formed a hook echo, which was fully developed four minutes later.
Observers reported wall clouds from the Yukon area into western portions of Oklahoma City during the next 10 to 15 minutes.
At 2:36 pm CST (20:37 UTC), the supercell produced a tornado near the Wiley Post Airport in Oklahoma City, causing damage at the Northwest Expressway.
According to the Doppler weather radar, the hook continued to show signs of rotation as it moved northeast across Oklahoma County.
At 2:52 pm CST (20:52 UTC), the supercell produced its second tornado on the northwestern side of Edmond which caused its most severe damage near the Oklahoma and Logan County line.
The tornado dissipated north of the Logan County Line at 3:05 pm CST (21:05 UTC).

The supercell produced three more tornadoes in Oklahoma as it continued to move northeast.
The third tornado occurred northwest of Meridian in Logan County at 3:26 pm CST (21:36 UTC).
A fourth developed near Langston in Logan County and moved to about 4 mi (6.4 km) southwest of Stillwater in Payne County.
The fifth tornado occurred in Pawnee County.
In addition to the five Oklahoma tornadoes, three tornadoes struck northern sections of Texas and one tornado hit Springfield, Missouri.

The most significant tornado, later named the Lone Grove Tornado, first touched down in southeast Jefferson County, Oklahoma at 6:48 pm CST (00:48 UTC) near the Red River.
The tornado crossed through rural areas as it moved to the northeast into Love County, before going into Carter County at 7:10 pm CST (01:10 UTC).
The tornado continued moving to the northeast for the next 15 minutes before striking Lone Grove, Oklahoma.
The tornado then crossed Interstate 35 just north of the Prairie Valley Road exit ramp and tracked through rural areas of northeastern Carter County to the east of Springer, ending at 7:43 pm CST (01:43 UTC).
During the afternoon hours of February 10, 2009, a strong, middle and upper storm system moved across the Four Corners region into the central and southern Great Plains. A moist, low-level air mass streamed northward across Texas and Louisiana into eastern Oklahoma and the Ozarks ahead of the system. Daytime heating of the moistening boundary layer increased throughout the afternoon across Oklahoma and Texas as cloud cover shifted eastward. Cooling aloft, in conjunction with the approaching storm system, led to atmospheric instability, resulting in thunderstorms. A very strong wind field increased with height through the lower troposphere, resulting in a wind shear favorable for rotation in the thunderstorms.
Meteorologists expected large hail stones and damaging winds, and recognized the potential for strong tornadoes as thunderstorms developed from central Oklahoma southward into north-central Texas in the afternoon. During the night, a cold front moved eastward toward the Mississippi Valley and organized the thunderstorms into a lengthy squall line. Along with a continued threat of hail and tornadoes, the risk of damaging winds increased. The Storm Prediction Center announced a "moderate risk" of severe weather for portions of eastern Oklahoma, northeastern Texas, western Arkansas, and northwestern Louisiana.
At around 1:00 pm CST (19:00 UTC), a line of violent thunderstorms began developing near the Wichita Mountains in Comanche County, Oklahoma. The supercell that eventually produced the first tornado of the outbreak moved northeast through Caddo and Grady counties over the next 30 to 45 minutes, before reaching southeastern Canadian County at around 2:00 pm CST (20:00 UTC). By 2:14 pm CST (20:14 UTC), the line had formed a hook echo, which was fully developed four minutes later. Observers reported wall clouds from the Yukon area into western portions of Oklahoma City during the next 10 to 15 minutes. At 2:36 pm CST (20:37 UTC), the supercell produced a tornado near the Wiley Post Airport in Oklahoma City, causing damage at the Northwest Expressway. According to the Doppler weather radar, the hook continued to show signs of rotation as it moved northeast across Oklahoma County. At 2:52 pm CST (20:52 UTC), the supercell produced its second tornado on the northwestern side of Edmond which caused its most severe damage near the Oklahoma and Logan County line. The tornado dissipated north of the Logan County Line at 3:05 pm CST (21:05 UTC).
The supercell produced three more tornadoes in Oklahoma as it continued to move northeast. The third tornado occurred northwest of Meridian in Logan County at 3:26 pm CST (21:36 UTC). A fourth developed near Langston in Logan County and moved to about 4 mi (6.4 km) southwest of Stillwater in Payne County. The fifth tornado occurred in Pawnee County. In addition to the five Oklahoma tornadoes, three tornadoes struck northern sections of Texas and one tornado hit Springfield, Missouri.
The most significant tornado, later named the Lone Grove Tornado, first touched down in southeast Jefferson County, Oklahoma at 6:48 pm CST (00:48 UTC) near the Red River. The tornado crossed through rural areas as it moved to the northeast into Love County, before going into Carter County at 7:10 pm CST (01:10 UTC). The tornado continued moving to the northeast for the next 15 minutes before striking Lone Grove, Oklahoma. The tornado then crossed Interstate 35 just north of the Prairie Valley Road exit ramp and tracked through rural areas of northeastern Carter County to the east of Springer, ending at 7:43 pm CST (01:43 UTC).
Tornado outbreak of February 10–11, 2009