Photos:

Storm Damage Photos

Iron Mountain - City Park. Courtesy Mountain-Daily News	Russell Street Iron Mountain - Courtesy Tracey Steeple	M73 Culvert Washout - Courtesy of MDOT	M73 Culvert Washout - Courtesy of TV6

Radar:

Radar Summary - MRMS (Multiple Radar Multi-System) Platform 11June2017

Storm Reports:

Environment/Meteorology:

A warm moist frontal boundary started the day oriented across South-Central Minnesota to Central Wisconsin. In addition to this boundary, was a surface ridge centered over the Southeastern United States. As the day progressed, the frontal boundary began to lift north towards the U.P. with increasing instability from Minnesota to Wisconsin. Images below indicate the dewpoint (color shading), which was well above climatology with dewpoints in the lower to middle 60s. Meanwhile to the north of the boundary dewpoints were much cooler in the middle to upper 50s.

Temp/Dewpoint/MSLP 12Z (8AM EDT)	Temp/Dewpoint/MSLP 15Z (11AM EDT)	Temp/Dewpoint/MSLP 18Z (2PM EDT)	Temp/Dewpoint/MSLP 21Z (5PM EDT)

The upper level wind pattern supported deep layer flow from southwest to east/northeast from the analyzed 300hPa. Images below indicate the upper level winds (shading) and in pink is the upper level divergence. This divergence is in indication of where the strongest or most dynamic environment existed, and also suggests where the strongest low-level convergence may have been present.

Jet Stream (300hPa) 12Z	Jet Stream (300hPa) 15Z	Jet Stream (300hPa) 18Z	Jet Stream (300hPa) 21Z

With the surface ridge centered over the Southeast CONUS, the Gulf of Mexico became the main source for moisture or what we call return flow moisture. This moisture feed was being pumped north through the Ozarks into the Ohio Valley and Western Great Lakes/Upper Midwest as the mid-level flow was from the south/southwest. The stronger mid-level shortwave that was producing extensive severe thunderstorms across the Central Plains slowly lifted northeast towards the Upper Midwest/Western Great Lakes later in the day.

850hPa HGHT/Temp/Td 12Z	850hPa HGHT/Temp/Td 15Z	850hPa HGHT/Temp/Td 18Z	850hPa HGHT/Temp/Td 21Z

In addition to the severe weather concerns of damaging winds and hail, was heavy rain. With the abnormally moist airmass, and the tropical origins of the Western Gulf of Mexico, thunderstorms could easily produce heavy rainfall in a short period of time. The upper level pattern (300hPa images above), also suggest that as storms developed upstream (west/southwest) of the U.P. they would continue to follow northeast along this axis.

850hPa Moisture Transport 12Z	850hPa Moisture Transport 15Z

High-Resolution forecast models have continued to improve over the recent decade, and with technological advancements this allows forecasters to improve the ability to relay with higher confidence when/where weather will develop and impact. While there are still some limitations, on Sunday morning the HRRR forecast model performed relatively well in depicting the placement and timing of the expected storms later in the day. Below is the animation of what the radar may look like during the convective event. The timing ended up being about an hour early and slightly too far north.

HRRR Forecast Radar 11June2017

Other Links:

This area will continue to update with additional information about resources in regards to various items we have discussed above.