Gathering storms prompt US Midwest ‘derecho’ warning

Weather forecasts expecting a burst of storms to form over the key growing regions of the US Midwest have sparked fears that the gathering fronts could combine to form a derecho in the days ahead, a rare meteorological phenomenon that brings high winds across widespread areas.

A similar event last season affected miles of corn plantings across major producing states in August last year, which brought particular damage to swathes of US corn plantings at a critical stage of development.

“The big change was that the GFS [Global Forecast System] had important storms firing up over the Iowa/Minnesota border tomorrow, moving into northern Illinois and northern Indiana Friday,” noted global head of grain futures at ED&F Man Charlie Sernatinger in a note to clients on Wednesday.

“In fact, at least one service is calling for a ‘derecho’ through those areas,” the note warned.

However, market sources have highlighted that the weather pattern is very difficult to forecast and the crop is still emerging – meaning it faces potentially less risk from wind-related damage.

Storms are expected today and tomorrow across the Midwest, according to meteorological outlooks, and there is the possibility for the phenomenon to occur – but it is unlikely to match the intensity reported in August.

“A derecho event cannot be completely ruled out, but someone out there seems to be hyping up this event and comparing it to the derecho in Iowa last year that caused major damage,” Kyle Tapley of Maxar weather services told Agricensus.

“However, that was an historic and extreme event and there is little to indicate that the storms over the next couple of days will be comparable to that event,” Tapley said.

US corn is at a critical juncture, with planting just concluded and 96% of the crop now emerged, but dry conditions mean weather is already a concern for the new crop.

Headlines around heavy weather could renew upward momentum at a time when corn futures have slumped, along with falls on the wider agricultural complex, amid poor demand and improved production prospects.

After last year’s storm I learned quite a bit about the phenomena, but what stuck with me is that they’re incredibly hard to forecast.  The Midwest is no stranger to storms of all kinds, so it’s safe to assume that we’ll have all kinds of thunderstorms, tornadoes, etc. and hope that we don’t see anything like last year’s derecho.