Wind-driven downpours arrive Thursday (some thunder possible late) Still windy Friday with lingering drizzle; warm and muggy next week

A strong late summer storm will be affecting the upper Midwest and western Great Lakes through Friday. For the Northland, this storm will bring strong northeast winds to areas near Lake Superior with waves of rain lifting N/NE through the area on Thursday. A few thunderstorms are also possible Thursday into Thursday evening. Lingering drizzle, light rain and gusty west winds continue on Friday.

Source: 12z HREF model; https://www.spc.noaa.gov

Flash Flood Watch is in effect from 9 PM this evening through Thursday morning for portions of west-central, central, east-central and southern Minnesota.

Significant River Flooding is possible through September 16 in the shaded areas on the map below. Source: https://www.weather.gov/ncrfc/LMI_FOP_summary

Water vapor satellite loop from Wednesday shows a strong storm churning N/NE across the Northern Rockies, this is the system that will move into the upper Midwest on Thursday. Note: This storm is producing mountain snow today in far southern Montana. Source: https://weather.cod.edu

18z HRRR model radar forecast valid from 7 this evening to 6 AM Friday.

Rain with embedded downpours and thunderstorms gradually lift north and east into the Northland during the day Thursday. Rain tapers off from SW-NE Thursday night.

Source: https://weathermodels.com

Much of the Northland has potential to pick up an inch or two of rain by Friday morning.

Source: https://lab.weathermodels.com

Low pressure will really wind up Friday as it lifts northeast out of northwestern Minnesota. Cold air advection will sweep up from the south on Friday with 850mb temps Friday morning ranging from around 0C in western Minnesota to around +10C near Thunder Bay Ontario.

Source: 12z European model; https://www.tropicaltidbits.com

Low temperature forecast for Thursday morning, September 12. Source: https://graphical.weather.gov

High temperature forecast for Thursday, September 12

Note: At least 3 tornadoes tore through Sioux Falls, South Dakota late Wednesday evening, September 10, 2019. 9 injuries were reported. Link to additional information on these tornadoes from the National Weather Service in Sioux Falls, SD https://www.weather.gov/fsd/091019_siouxfalls_tornado

Next week’s warm up is still on track. Computer models continue to show a strong upper level ridge setting up over the Midwest with very warm and humid weather occurring in the Northland from about September 15 through September 19. Daytime highs in the mid 70s to mid 80s are looking quite likely with overnight lows possibly holding in the 60s! Dew points in the 60s to around 70 degrees are also expected on multiple days next week with the most humid days from Monday through Thursday the way it looks now.

Source: 00z European model; https://www.pivotalweather.com/

…Weather Summary…

Upper level pattern features a ridge across the southern/eastern U.S. and a trough which is lifting north/east across the Northern Rockies.

First round of rain earlier today affected far southern portions of the Northland pretty much what was expected to happen. Rainfall totals from today include

• Hayward, WI: 0.63″
• Siren, WI: 0.43″
• Hinckley, MN: 0.28″
• Solon Springs, WI: 0.05″
• Ashland, WI: 0.04″
• Brainerd, MN: 0.03″

More rain will gradually develop tonight in western/southern areas of Minnesota, this rain will slowly lift to the north and east Thursday morning but as it moves into the Northland it will be running into drier air associated with a strong area of high pressure near Hudson Bay. Eventually the low over the Northern Rockies will win out and will transport deeper moisture north into our area, as this happens will begin to see some rain break out across the Northland Thursday morning or early Thursday afternoon.

As the surface low approaches from South Dakota, atmospheric lift will increase from about mid afternoon Thursday through late Thursday evening, this is when we should get the bulk of the rain to fall in the Northland. Embedded downpours and thunder are likely especially from Thursday afternoon through Thursday evening as this is when will see the strongest combination of warm air and moisture advection move into our area along with a push of higher elevated instability (MUCAPE) thanks to a strengthening low level jet.

Note: Gusty east winds will continue near Lake Superior through Thursday evening. Winds of 15 to 25 mph with gusts to 30 mph will continue through Thursday morning, followed by potentially higher wind gusts approaching 40 mph Thursday afternoon into Thursday evening as the teeth of this storm lifts into the Northland.

Forecast for Duluth and Superior

.Tonight… Windy. Mostly cloudy. Patchy drizzle or fog possible. Low 47 to 52. Wind east 15 to 30 mph.

.Thursday… Windy. Drizzle and fog. Occasional rain with embedded downpours. Isolated thunderstorms possible late. High 52 to 55. Wind east 15 to 30 mph with gusts to 40 mph.

.Friday… Breezy. Mostly cloudy. Light rain and drizzle. High 52 to 57 with near steady or slowly falling temperatures. Wind southwest 15 to 25 mph.

Normal temperatures for Thursday

• High 67
• Low 48

• Sunrise Thursday 6:42 AM CDT
• Sunset Thursday 7:27 PM CDT

Thanks for reading!