/Issued 8:40 PM CDT, Saturday, July 7, 2018/
Risk of flash flooding returns to portions of northeast and east central Minnesota Sunday night.
00z HRRR model run — Simulated Radar Forecast valid from 10 PM tonight to 1 PM Sunday. Scattered thunderstorms should develop later tonight and persist through Sunday morning across northern Minnesota, these storms could produce torrential downpours and localized flooding with a few strong to severe thunderstorms possible as well.
Isolated to scattered strong to severe thunderstorms could develop late tonight or early Sunday morning mainly over far northern portions of Minnesota
Isolated to scattered strong to severe thunderstorms possible over the entire Northland on Sunday. Storms will mainly be over northern Minnesota Sunday morning, then late Sunday afternoon through Sunday night will feature the greatest thunderstorm chances a little farther south to include northeast and east central Minnesota into northwest Wisconsin.
A warm and breezy summer day under sunny to mostly sunny skies, highs topped out in the mid 80s, and it was muggy especially in northern Minnesota where dew points were in the upper 60s to lower 70s this afternoon, not as humid farther south with dew points generally in the upper 50s to lower 60s.
A cold front will move into far northwest Minnesota by early Sunday afternoon, this front will move farther south/east and is forecast to reach central Minnesota into northern Wisconsin by Monday morning.
Warm, humid and unstable air will be found near this cold frontal boundary along with a 30 to 40 knot southwesterly low level jet. Dew points ranging from the mid 60s to mid 70s through Sunday evening with PWATS of 1.30 to around 2.25 inches (Lots of moisture in the air!)
As for instability, forecast models cranking out anywhere from 1500 to ~3000 j/kg of CAPE with the higher values focused over parts of north central Minnesota.
Upper level winds of ~100 knots off to our north with mid level winds about 30 to 50 knots over the Northland. Looking at about 30 to 40 knots of deep layer shear which supports stronger thunderstorm activity.
For tonight through Sunday morning thunderstorms that develop should remain over far northern Minnesota, mainly along and north of a line from Grand Rapids to Grand Marais.
Scattered showers and thunderstorms could very well linger most of day on Sunday in northern Minnesota while a mix of sun and clouds occurs a little farther south — Then will see additional thunderstorms which could be strong to severe redevelop late Sunday afternoon or Sunday evening in north central and northeast Minnesota. Thunderstorms will tend to move easterly, well the line itself pushes toward the southeast.
Damaging wind gusts and large hail will be the main hazards from severe thunderstorms through Sunday evening.
Warm tonight with lows ranging from the lower 60s to lower 70s; Highs Sunday in the 80s with a shot at 90 degrees mainly over southern portions of the Northland.
Note: Stay weather aware through Sunday night as severe thunderstorm watches, warnings, and flood advisories or warnings could be issued at times in parts of the Northland.