Widespread heavy rainfall of 3 to 10+ inches of rain has fallen across much of the Midwest in the past 2 weeks. This has led to moderate to major level flooding across parts of Missouri, Illinois, Indiana and Western Ohio. The graphic below provides a snapshot of the past 2 weeks of rainfall.
The graphic below highlights the current flooding situation due to the heavy rainfall. The locations in red are at moderate flood levels while the areas in purple are at Major flood levels.
As a reminder:
Moderate flooding means some inundation of structures and roads near the stream/river. Some evacuations of people and/or transfer of property to higher elevations may be necessary.
Major Flooding means extensive inundation of structures and roads. Typically major level flooding causes significant evacuations of people and/or transfer of property to higher elevations.
The flooding has already caused significant crop damages. According to a recent article published on AgWeb, damages to the soybean and corn crops in Indiana alone are over $300 Million. These estimates are expected to increase once the flood waters recede and full assessments can be completed.
Unfortunately, more rain is in the forecast for this week. While at this time, the heavier amounts are mainly forecast to be to the south of the area that is seeing the worst flooding, widespread rainfall amounts of 1.0 to 1.75 inches are expected (see below). In addition, any additional rainfall could further complicate the ongoing flood situation and at a minimum prevent fields from drying out.
Below is the Official River Forecasts for the next five days. The color in the outer edge of the square shows the expected forecast levels while the inner square highlights the current conditions. For the most part, the flooding is not expected to significantly worsen with the forecast rainfall.
However, an item of concern is the potential for isolated higher rainfall amounts, especially in areas of that see repeated thunderstorms. Tonight as well as Tuesday afternoon and into Tuesday evening are the days with the increased risk of isolated higher rainfall amounts. Below is a perspective of the possible highest rainfall totals with a 90% statistical confidence. It indicates that amounts are not expected to exceed 1.25 inches late tonight and into early Monday. Similarly, maximum precipitation amounts are forecast for Tuesday evening across this region.
However from a river forecast perspective, if the higher rainfall amounts occur the river flooding will likely be prolonged.
As an example, the forecast above shows the official river forecast for the Wabash River at The William Henry Harrison Bridge near West Lafayette, IN. This forecasts incorporates rainfall from today through midday on Tuesday (approximately 1.25 to 2 inches or rainfall). However if the higher isolated amounts occur in the Wabash River Basin upstream of the river gauge, the graphic below provides some “what if scenarios” when considering the additional precipitation.
The graphic on the left highlights that the flooding situation is not expected to worsen with the higher rainfall amounts tonight and Tuesday as well as with another event toward the end of the week. The impact of this additional rain is to cause the recession of the river to be slower. This is the common picture across the Midwest. However slower recessions of area rivers and streams may increase the damages especially for agriculture.
The team at WxIntegrations urge individuals in the Midwest especially those in low-lying areas and along rivers to remain aware of the potential of compounding impacts due to additional rainfall expected this week. Our goal is provide you the information and resources to help you better understand and prepare for the forecast weather through incorporating weather impacts into your planning and response.