National Weather Service United States Department of Commerce

Landspout Tornado near Chuichu, AZ

Monday Sep 16 2019 - 1:55pm MST

 

During the early afternoon hours of Monday Sep 16, showers and thunderstorms developed across portions of southern Arizona within an environment of increased instability and wind shear. Ahead of one cluster of storms near Chuichu, AZ, storm spotters (link | link) photographed a series of landspout tornadoes that developed over open desert around 1:55 pm.  No damage was reported or observed in this area and the landspouts dissipated within a few minutes. 

 

Location: 32.70N 111.84W

Rating: EF0 (65-85 mph)

Damage reported: None

 

Approximate location of landspout tornadoes

 

KEMX Base Reflectivity (L) and Storm Relative Motion (R) imagery from 1:35 pm - 1:55 pm MST. Approximate location of landspout tornadoes shown by red marker. 


 

What is a Landspout Tornado?

From the Glossary of Meteorology and NSSL, there are two types of tornadoes: those associated with supercell thunderstorms, and those that are not.  Although the environment on Sep 16 was conducive for supercell development, this tornado in particular developed ahead of an approaching thunderstorm in an area not associated with the storm's rotating mesocyclone. A landspout tornado is a tornado with a narrow, rope-like condensation funnel that forms while the thunderstorm cloud is still growing and there is no rotating updraft. The spinning motion originates near the ground and is stretched upward. In supercell tornadoes, the spinning motion originates in the storm and descends downward. Landspout tornadoes tend to be much weaker and shorter lived than their supercell counterparts, with wind speeds rarely exceeding 100 mph.

 

Tornadoes are not unheard of across Arizona and according to the Storm Prediction Center's 2019 summary, this is the 3rd tornado in the state so far this year. According to the National Centers for Environmental Information (NCEI) Storm Events Database, there have been nearly 250 documented tornadoes in the state of Arizona since 1950, with an average of approximately 3-4 per year.