KMSP - Although much of the state has seen some rain in the last few days, (a small chunk of us have seen some flooding rains) many areas have really started to dry out when we entered the month of July. Contrary to the last couple of years, our rains have started to dwindle instead of increase as we have pushed through the month. Now, the overall effects from this drying trend have been pretty small so far, mostly because April, May, & June in were at or above average for precipitation across all but the northwest corner of the state.
July is not only the wettest month on average, but it's also our warmest month on average. So if we go a few days without rain, things can dry up fast. But it's also the time of year when rainfall rates (the rate at which rain is falling) are also typically at their peak. So, one or two thunderstorms over one spot can literally give you a months’ worth of rain. Take this past Wednesday as a good example with areas of Dakota County and points southeastward down the Mississippi River Valley getting their months’ worth of rain in just a few hours. But the ground unfortunately can't soak up water that quickly, so much of it runs off into area creeks and rivers and becomes more of a waste than it is actually useful. This is why much of our green can begin browning during the month because not only do we need rain, but even if we are above average, much of it may not get used because of how fast it came down. It's for these reasons that many areas of the Upper Midwest during July and August have a "feast or famine" type problem. There's either too much water around or not enough. Over the last couple of years, there has been way too much. But this year we have hit a bit dryer period and now things are starting to brown a bit, especially north and west of the metro.
Just look at the image above with the percent of normal precipitation across the Upper Midwest from the middle of June to the middle of July. Much of the state has seen less than half the average. Combine that with temperatures that have been above average, and you have a recipe for a browner looking landscape.
This lack of rain puts stress on area plant life. One way to see how well the plants, trees, and crops are coping with our precipitation is the Vegetation Drought Response Index. This index is calculated by integrating satellite based observations of vegetation conditions, climate data such as temperatures and precipitation, and other biophysical information such as land cover/land use type, soil characteristics, and ecological setting. The 1 square kilometer resolution of this index is far better than the US Drought Monitor, which is where drought information is typically gathered and stored for climate data for the National Weather Service.
You can see by the images above that while the metro is fairly stress free at the moment, much of the area was littered with lights and dark greens just a few weeks ago, showing well above average moisture. And now, we are starting to trend much dryer. Clearly, the worst part of the state is in parts of the west. The area around Bemidji, and then parts of southwestern Minnesota where 6”+ of rain is needed to get back on track.