Mainly dry Monday, rain moves in Tuesday

The chances for a widespread rain event across Southeastern Minnesota and Northern Iowa are increasing for the Monday night – Wednesday timeframe.

Upper level troughing centered over the Rocky Mountains continues to advance east as we close out the weekend. Ahead of this trough, surface low pressure is developing. Over the next 24-48 hours, this low will approach the region, but is expected to remain mainly south of the area.

Despite this, the surface low and upper level trough will provide significant forcing over Minnesota and Iowa once they arrive. Ahead of these features, copious amounts of moisture will be streaming northward. This moisture, along with the high levels of forcing across the region, will set the stage for a widespread rain event.

Clouds will increase tonight, and into Monday as the low approaches. There is the chance for a broken line of dissipating showers to pass through the area Monday morning. Dry air near the surface will likely make it difficult for associated rain to reach the ground, and not everyone will see rain.

The better moisture and forcing arrive Monday night, with widespread light to moderate rain expected across all of Southeastern Minnesota and Northern Iowa Tuesday morning. In just this time frame alone, there are indications that much of the viewing area could easily pick up 1″ of rain, especially along and south of I-90.

Some dry air may work its way into the system Tuesday afternoon, leading to a break in the widespread precipitation. However, with moisture circulating around the low, it is likely rain will redevelop heading into Tuesday night, and last through at least the first half of Wednesday.

Many locations may see an additional 0.5″ – 1.00″ of rainfall accumulation during this time, primarily along and south of I-90 once again.

By Wednesday afternoon, the upper level low begins to depart the area, along with the best supply of moisture. Rain chances will decrease Wednesday afternoon, before coming to an end Wednesday night.

By Thursday, clouds will have exited the area as well, giving way to mostly sunny to partly cloudy skies.

The entire viewing area has a fair shot at receiving 1″ of rain between Monday night and Wednesday. Many locations will likely see much more, with model guidance hinting at 2+” in isolated spots. Rain totals are subject to change, and depend on finer details that will be better understood Monday. The flood risk is low, despite these high totals, given how dry we have been the last few weeks.

For the time being, this is a promising chance for the entire viewing area to see a soaking rain that we have not seen the entire month of May, and certainly could use!