Late June severe t-storms and heavy rain
25-29 June 2021

After a couple of hot and dry weeks through the middle of June, the weather took a sharp turn back toward the cooler and wetter side. The shift back to the late May and early June-like weather was inspired by the approach and passage of a cold front and slow-moving upper level trough.

The active stretch kicked off in earnest with a bout of widely scattered thunderstorms Friday evening (25 June).  The initial storms developed along and ahead of a dryline, then raced east and northeastward across the South Plains region. Relatively hot and dry conditions in place kept rainfall spotty, but did support strong downdrafts that produced severe gusts.

Instability and wind shear waned in the following days, but abundant moisture lingered. The near-record level moisture fueled several rounds of tropical showers and the occasional embedded thunderstorm. The main impact from these showers were periods of torrential rainfall, though they did also support several tropical-type funnels, and even a brief landspout or two. 

The landspout-type tornadoes did no known damage, as is generally expected since they often do not persist long or contain very strong winds. However, where the tropical showers trained they unloaded excessive amounts of water that led to flooding. On Monday morning, June 28th, the Lake Alan Henry area experience a prolonged period of moderate to heavy rain. The Lake Alan Henry WTM recorded 5.18 inches on the 28th, much of which fell in a 3-hour period centered around 9 am. The excessive rain flooded portions of Highway 84 between Post and Justiceburg and inundated structures near Lake Alan Henry. 

Runoff from the heavy rain did result in significant rises on Lake Alan Henry, lifting it nearly 4 feet, and pushing it back over the spillway (to 111% of capacity). White River Lake rose about 2 feet, causing it to rise from 19% to 25% of capacity.

The preliminary storm reports collected during the active late-June stretch can be found below.