Good Afternoon! Here are your latest updates:
Multiple showers and storms moved through the area last night bringing widespread rainfall totals up to 1.75 inches in central South Dakota.
Last 24 hour precipitation totals:
Tonight another round of storms will be moving through the area bringing the chance of large hail and strong winds across the majority of South Dakota and southern Minnesota. There will be the chance of an isolated tornado this evening primarily in South Dakota where there will be more low-level energy and turning of the winds.
Low-level energy at 7pm this evening:
Upper-level energy tonight through Thursday Evening:
Why do these storms typically happen right around when it starts to get dark? Once the sun begins to go down and it isn’t warming at the ground anymore there is an imbalance in the atmosphere. The ground starts cooling faster than the air above it creating a temperature difference. When you get temperature differences like this, jet streams (or pockets of strong winds) develop in the lower levels of the atmosphere. These jet streams provide more lift for these storms so it allows them to grow much quicker and get stronger. Areas inside the region circled below will have this enhancement. This allows storms to develop larger hailstones, stronger winds, and a greater tornado potential than in an area that is not being influenced by a low-level jet stream.
Image of the low-level jet stream tonight:
Modeled Radar reflectivity for tonight through Friday morning:
Now just as we have been talking about for this entire season so far there have been a lot of these systems coming through that bring 1+ inches of rain. That being said it does not take that much precipitation anymore to have a risk of flash flooding.
Here is what we currently need in a 1 hour period to get flash flooding:
The majority of the northern plains only needs 1.5-2″ of rain in a one hour period to cause flash flooding. That being said, these storms will develop quickly and they will also have a sufficient moisture supply to dump 1+” of rain in isolated areas this evening. Tonight into tomorrow most areas in South Dakota, southeastern North Dakota, and south/central Minnesota should expect 0.5-1.5″ of rain. There will be isolated pockets under the heaviest part of this line that could get 1.5-2+”. Here is an image of the available moisture for precipitation to pull from this evening. The main focus for rain tonight will be in SW SD, however this line will move into ND and MN in the overnight hours and into tomorrow:
Precipitable water loop (how much rain can fall based on how much moisture is in the atmosphere) through Thursday evening. The purple shades are Precipitable Water values greater than 1.5 inches. As this loop shows, this storm cluster will have plenty of moisture to work with as it moves SW to NE and is capable of putting down an inch or better in some spots:
Model forecasted rainfall for tonight through Thursday afternoon. Current thought is that NW ND could see more precip than what is modeled due to more upper level energy passing over that area early tomorrow morning:
As always, if you have any questions or would like more localized forecast details please do not hesitate to reach out to us at [email protected] ! Enjoy your evening!