A chaotic high-altitude jet stream will cause scattered showers and storms over much of the Ohio and Tennessee Valleys next week.
Indiana, USA – The last week of July is going to be rough. The pattern on the upper level, or rapids, is sloppy. The front line was slow and weak. Heat and humidity will increase. Put it all together and you get a messy and somewhat random forecast. Scattered showers and storms are possible anytime next week, especially in the afternoon and evening.
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This storm area is very large. The unsettled weather may be strongest from Minnesota to Indiana to Florida. Large scattered showers and downpours are possible across much of the Corn Belt, Ohio Valley and Tennessee Valley.
For Indiana, rain will likely begin Sunday and continue throughout next week.
Weather Settings | Why is it so messy?
We have a non-uniform two-barrel high-pressure system. Wind flows clockwise around low pressure. When two storms are close to each other, the winds become more chaotic and can create convergence (winds coming together), forcing the divergent storms to suddenly appear. In addition, the high pressure in the east is weaker than the high pressure in the west. This will only further create unevenness in the atmosphere. This all adds to the confusion factor in forecasting.
Our map of the rapids rises northward over the western plains. The interesting part, however, is the northwest flow slope from Iowa to West Virginia. This area helps produce the most storms in summer patterns like this, mainly because the northwest flow really distorts the upper atmosphere, which helps clouds develop, leading to more rain and storm opportunities.
The green areas show areas where we can expect a higher chance of heavy rainfall. The area then extends southward. That's because when storms break out in the north, they can make their way south toward the Gulf Coast. Storms like to move into areas with higher temperatures and humidity. The Deep South can provide that.
Building heat and humidity
You need energy (heat) and water (humidity) to create a storm. We'll all get it next week. It's already warm temperatures in Indiana in late July, with most temperatures in the 80s and some in the 90s. Humidity also increases over time. This will only lead to more unstable weather. Starting Monday, the heat index will top 90 degrees.
Next week, as July comes to an end, the air will become very tropical. While it won't rain, expect sunshine and muggy air. It's Florida air. This will help the development of random storms.
On which days will it rain?
Scattered rain and storms are possible every day next week. However, their range is closer to 50-50. Some will rain, some won't. Many Indiana towns may not have much water all week, while others are soaked.
It's hard to focus on who's most likely to rain when you still have a few days left. In this environment, we can only get more specific information starting 24 hours in advance. How rain and storms form one day will affect how they form the next day.
How much rain are we likely to get?
There are estimates everywhere. Rainfall amounts are generally expected to range from 0.5 inch to 2 inches next week. In some places we will get less, and in other places we will get more. It depends on where the individual downpours occur.
Check back each day to see if there is a chance of rain the next day. You can still have a great week outdoors! As the likelihood of storms increases, especially in the afternoon and evening, be prepared to temporarily move indoors.
