Good Thursday afternoon everyone! A strong line of storms has begun to develop across southeastern SD into southwestern MN with scattered showers and heavier storms working eastward near Minneapolis, MN. Further north and west, a large rain shield can be noted across eastern ND, northwestern MN and portions of northeastern SD as of 3:45pm CDT. The severe weather threat is expected to increase through the evening hours across southern MN.
The SPC is highlighting southern MN for the development of strong to severe thunderstorms this evening. A strong line of storms is expected to track through these areas with possibly a few supercells leading out ahead of this line in these areas. Any supercells that develop across southern/southeastern MN will have the potential to put down tornadoes due to strong wind shear, helicity (or spin) and instability present in the area. Damaging winds and large hail may also accompany these storms. This happens to be where a warm front is currently positioned, which only adds to the risk as warm fronts can outperform. As the line progresses through southern MN this evening, a few brief spin-ups are also possible along its leading edge. Any tornadoes that develop along the line will likely be rain-wrapped so definitely be on-guard this evening given the high threat in the region.
A Tornado Watch has been issued for portions of southern MN until 11pm CDT due to the environment destabilizing and strong to severe storms set to become more frequent. A cold front will push through the area tonight, kicking these storms out of the area.
Simulated radar through 1pm CDT Friday: A strong to severe line of storms will develop and track through southern MN through the evening hours, gradually lifting out by 12am CDT tonight, though some residual rain on the backside of the complex of storms may persist overnight. As noted earlier, a few supercell storms may develop out ahead of this line (not depicted by this model but very possible) before merging with the main feature as it works through. Heavy, stratiform rains across northern MN and ND will work west to east overnight into tomorrow morning. Most of these rains will have departed ND by 7am CDT Friday and northern MN by 1pm CDT. Far northern SD may get clipped by these rains overnight tonight into early tomorrow morning.
Total rainfall through 1pm CDT Friday: The stratiform rain across ND and northern MN will likely dump anywhere from 0.5-1.5″ of rain with locally higher amounts possible. Where the strong storms are most likely (southern MN) a quick 0.5-1″ of rain with locally 2″+ is possible as the line progresses through these areas. Most of SD will stay dry after the stratiform rain in the northeastern portions of the state departs.
If you have any questions do not hesitate to reach out! Have a great evening!