6:34 PM Monday, May 20, 2024
- The Northland is expected to experience several rounds of rain and intermittent thunderstorms, starting late tonight and persisting through Tuesday night.
- Flash flooding due to excessive rainfall is possible from Tuesday to early Wednesday morning, particularly in north central and east central Minnesota. These areas are likely to experience prolonged rainfall, whereas other parts of our region may see intermittent rain with occasional breaks.
- There is a low risk of a few strong to severe thunderstorms from Tuesday into Tuesday evening, primarily affecting northwest Wisconsin and the far eastern region of Minnesota.
- Expect gusty winds ranging from 20 to 35 mph Tuesday into Wednesday, with gusts exceeding 45 mph. The winds will originate from the northeast on Tuesday, transitioning to northwest late Tuesday night into Wednesday.
A potent low-pressure area, accompanied by a negatively tilted upper-level trough, is expected to move northeastward from the central and northern Plains into the upper Midwest between Tuesday and Wednesday.
At this time of year, the system is remarkable, with a significantly deep surface low decreasing from 994mb earlier this evening to approximately 984mb as the low passes over northern Minnesota around daybreak on Wednesday.
This system will have abundant moisture and lift, which is expected to result in widespread rain and embedded thunderstorms across the Northland from late this evening through Tuesday night, with some residual rain continuing into Wednesday morning.
The upcoming system should experience ample upper-level support/lift, thanks to two robust jet streaks exceeding 100 knots—one positioned north of Minnesota and the other spanning the central Plains. This configuration places the upper Midwest squarely between the two zones of most intense winds aloft, which is likely to result in increased atmospheric lift both Tuesday and Tuesday night.
Duluth area: There’s a chance for a few showers tonight, however, most of the rainfall from the upcoming system is expected on Tuesday and into the night, with potential for some residual showers on Wednesday. While isolated thunderstorms could occur, bringing the possibility of heavy downpours on Tuesday and Tuesday night, severe thunderstorms are not anticipated in the Twin Ports area.
NAM 3km model simulated radar forecast through 7 AM Wednesday.
The Northland is expected to receive widespread rainfall, with totals likely ranging from 1 to 2 inches through Wednesday morning. Some areas may see higher accumulations, exceeding 3 inches.
Here is an additional model forecast predicting rainfall totals through Wednesday morning.
The forecast displays the ensemble’s maximum rainfall totals as predicted by the HREF model..
Certain areas of Minnesota and Wisconsin may receive 2 to 4 inches of rain by Wednesday morning, with isolated regions potentially experiencing 5 to 7 inches within the larger 2-to-4-inch range via the HREF model forecast.
NAM 3km model wind gust forecast valid 7 AM Tuesday to 7 PM Wednesday.
The emergence of green colors on the map across Minnesota and Ontario Tuesday night into Wednesday indicates the intensification of a 500mb system progressing through the region.
EPS model 500mb forecast valid 7 AM Tuesday to 7 PM Wednesday
On Tuesday, a sharp thermal gradient is expected to accompany this system, with 850mb temperatures varying from about +5C in northwest Minnesota to up to +17C in eastern Minnesota and west-central Wisconsin.
A flood watch will be in effect from Tuesday to Wednesday morning across all of northeast Minnesota and the far northwest portion of Wisconsin, encompassing cities such as International Falls, Bigfork, Grand Marais, Ely, Isabella, Hibbing, Grand Rapids, Silver Bay, Two Harbors, Duluth, Superior, Hill City, Pine River, Aitkin, Brainerd, Hinckley, Pine City, Walker, Solon Springs, and Siren.
-Excessive runoff may result in flooding of rivers, creeks, streams, and other low-lying and flood-prone locations.
Significant river flooding is possible in the yellow area on the map through Saturday, May 25th.
The potential for a few strong to severe thunderstorms exists Tuesday through Tuesday night, primarily affecting northwest Wisconsin and the far eastern region of Minnesota.
The highest risk for a few severe thunderstorms, including a slight risk (level 2 out of 5), spans across parts of northwest Wisconsin or in the yellow area on the map for Tuesday and Tuesday night.
Tornado outlook for Tuesday, May 21, 2024.
There is a low risk for a tornado late Tuesday afternoon/evening in the green area on the map. Note that areas farther south of the Northland face a higher risk for a few tornadoes during the same time frame.
Severe wind outlook valid for Tuesday, May 21, 2024.
Severe storms on Tuesday and Tuesday night could bring damaging winds up to 60 mph across all of northwest Wisconsin and far eastern Minnesota, with the highest risk areas highlighted in yellow on the map.
Severe hail outlook for Tuesday, May 21, 2024.
There is a possibility of a couple instances of large hail, up to the size of a quarter, on Tuesday and Tuesday night throughout far eastern Minnesota and the entirety of northwest Wisconsin.
Ample moisture is expected to fuel severe thunderstorms on Tuesday, with dew points in the 60s across the southeastern half of Minnesota and into western and southern Wisconsin.
Forecasters utilize the Energy Helicity Index (EHI) to predict potential areas for severe thunderstorms and tornado development. EHI values between 1 and 2 can indicate the possibility of tornadoes forming within supercell thunderstorms. For Tuesday, EHI values are forecasted to exceed 2 in southeast Minnesota and central/northeast Iowa. Indeed, there is a risk of a few tornadoes if storms stay discrete over an extended period on Tuesday.
Severe thunderstorms are anticipated across the Midwest on Tuesday, particularly affecting areas of Iowa, southeast Minnesota, Missouri, Wisconsin, and western/northern Illinois.
Moderate risk (red) level 4/5
Enhanced risk (orange) level 3/5
Slight risk (yellow) level 2/5
Marginal risk (dark green) level 1/5
The potential for a couple strong tornadoes (EF2 or higher) exists on Tuesday afternoon and evening, particularly in the designated hatched area on the map.
Here’s a look at our developing storm over the Rockies today via water vapor imagery.
Goes-16 water vapor loop ending 5:40 PM CT, Monday, May 20, 2024.
Thanks for reading!
Tim