Tropical air spurs intense thunderstorms Wednesday night
By Jared Shelton News-Press NOW meteorologist
After a much needed break from late-summer heat and humidity last week, the mid-Missouri River Valley has defaulted to the norm in recent days. Rather than below-average temperatures and relatively dry air, seasonably hot conditions have returned. In some cases, the summer sizzle has also been accompanied by moisture rich tropical air, not only contributing to steamy heat indices, but also supporting robust thunderstorm activity capable of producing impressive rainfall rates.
Wednesday night was a prime example of just how heavy rain can be when thunderstorms form in the presence of deep tropical moisture, even for landlocked areas such as Northwest Missouri. A slow-moving low-pressure system tracking across the Central Plains generated a line of intense thunderstorms that raked across Northeast Kansas on Wednesday evening, producing gusty to damaging winds, and even a brief rope tornado in Pottawatomie County, north of Manhattan Kansas. As storms moved eastward after sunset, the tornado threat subsided, but gusty winds, vivid lighting and torrential rain continued along and east of the Missouri River.
For St. Joseph and surrounding areas, rainfall was especially heavy as storms rolled in after 10 p.m. Wednesday. Deep convection within the line of thunderstorms tapped into the moisture-rich air, resulting in highly efficient rainfall rates. Rosecrans Memorial Airport recorded 1.42 inches of rain from 10:24 p.m. to 10:58 p.m., an impressive amount of water coming down in only 34 minutes. For reference, that works out to just over 2.5 inches per hour, a rainfall rate more common in tropical regions.
Wednesday night’s intense rainfall ultimately added up to 2.29 inches locally, well over half the monthly August average for St. Joseph. Despite a brief period of urban street flooding, surface soils were able to absorb the water without major issues, as minor drought conditions were starting to develop across Northwest Missouri and Northeast Kansas prior to the deluge. The next five to seven days will be in favor of those not interested in dealing with wet and stormy periods, as a sunnier stretch of weather is in the cards across much of the heartland.
