Monarch Weather Weekly: June 23, 2024

Floodwaters Devastate Iowa as Rivers Surge Downstream

Floodwaters have displaced residents in NW Iowa after weeks of rain, with Rock Valley particularly hard-hit and lacking running water. Several communities that were inundated on Saturday remained without water, passable roads and sewer services. How did this happen? Roughly 8-12" of rain fell over the course of 2 days over the Sioux Falls area (some isolated areas picked up 17” of rain) and now all that water is running through the rivers.

Image of Rock Valley, Iowa obtained from the Des Moines Register

Record flooding was reported along the Rock River in Rock Rapids and Rock Valley; the Big Sioux River in Hawarden and Akron; and the Little Sioux River at Milford. Charles City also experienced major flooding. Locally heavy rain is possible in those watersheds Tuesday, and there's a chance of more Thursday and Friday.

Multi-Day Severe Threat Plagues Plains, Midwest, and Beyond

Adding insult to injury, a strengthening low-pressure system will move along the U.S.-Canada border early this week, bringing a risk of severe thunderstorms to the northern Plains and Upper Midwest. Nearly 6 million people could experience strong, damaging wind gusts, large hail, and a few tornadoes on Monday afternoon and evening, including in cities such as Minneapolis. There is the chance for localized significant rainfall, as well, where nearly 1 to 1.5 inches of rain is possible that may lead to a couple instances of flash flooding where the ground is already saturated. Monarch’s Flood Risk Scoring will detail potential impacts to property, crops, and other business assets.

The same cold front will progress into the core of the Midwest and start spreading through the Ohio Valley on Tuesday and Wednesday finally knocking down the heat. Similar hazards remain in place — rather large hail, strong, damaging wind gusts, and the chance for tornadoes as the system targets the Chicago area, specifically on Tuesday. In total 19 million people are at risk for storms across other cities such as Milwaukee, Madison, and Detroit. These storms will likely progress into the Ohio Valley midweek where strong to severe storms may spread into the interior Northeast.

Potential Rain Totals by Friday, July 28th

Northern Plains Remain a Magnet for Storms

A separate system will develop out of the Rockies later this week with another round of strong to severe thunderstorms on tap for the Central and Northern Plains. There is the chance for more widespread rain with these storms that may lead to more flooding instances than the first system this week, with strong wind and hail being factors. Thursday and Friday are likely to be disruptive to supply chain and trucking logistics. Monarch specializes in precise forecasts at street and route levels, optimizing logistic efforts to ensure drivers get to their destinations efficiently and safely.

Heat Waves: A Rising Threat

Climate change is the primary factor behind the increase in heat waves, which have become four times more frequent since 2000. Extreme heat events are occurring much more often, with continual records of high global air and sea surface temperatures. Monarch offers assessments to help you forecast extended risks to your assets, projecting as far as 20, 30, 40+ years into the future. 


Mexico in the Crosshairs of Another Tropical System

Another tropical system will take aim at eastern Mexico and the southern tip of Texas early this week, delivering gusty winds and heavy rainfall. Impacts should be less from what Mexico saw from Alberto, but still impactful with up to 4 to 8 inches possible. The good news is that much of the region needed the rain and many Mexican ranchers benefited from the rain for their animals. 

Sponge Cities: Asia's Solution to Urban Flooding

As the average global air and sea surface temperatures continue to rise, along with sea-levels, many Asian cities are looking to brace for change. Urban adaptation is top of mind and the concept of ‘Sponge Cities’ is at the top of the list. Green spaces and waterways will help channel water underground. Coastal forests are being planted to contend with sea-level rise to soften the environmental impacts. The big question is if the efforts are too late.


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