/Issued 5:32 PM CDT, Friday, April 13, 2018/
Here’s my snowfall potential map — Majority of this snow occurs Saturday night through Sunday night.
Prolonged period of strong northeast winds will cause large waves to develop over Lake Superior through the weekend. Winds of 30 to 50 mph can be expected with the strongest winds occurring Saturday and Saturday night. There is potential for lakeshore flooding to develop Saturday into Sunday morning along portions of the North Shore of Lake Superior in northeast Minnesota, and for all of the South Shore of Lake Superior in northwest Wisconsin, or from near Two Harbors to Duluth to Ashland.
Potential impacts from Lakeshore flooding
•Beaches and shoreline areas which are oriented northwest to southeast are at greatest risk for infrastructure damage and beach erosion.
•Breaking waves will create hazardous conditions on breakwaters, jetties, and piers.
•The large and dangerous waves can deposit riprap and large chunks of ice on beaches and roads which are near the shore.
•Shoreline flooding and damage to structures such as parking lots, walkways, and roads, especially along northwest to southeast oriented shores.
•Venturing out onto breakwalls could put you at risk of being swept into the lake.
•Residents on or near the shore in the warned area should be alert for rising water, and take appropriate action to protect life and property.
RTMA model temperature analysis from Friday afternoon, April 13, 2018.
What a storm! Typical for spring, but always fascinating when it happens. Potential for severe weather and strong tornadoes south/east of the surface low while a major blizzard occurs to the west/northwest of the surface low.
Severe weather reports map from Friday morning, April 13, 2018.
Quite a few reports of severe hail ranging from quarter sized (1.00″) to as large as Golf Ball sized (1.75″) with the storms this morning in southern Wisconsin. Meanwhile in far southwestern Minnesota, severe storms produced winds of 75 to nearly 80 mph this morning!
Goes-16 one-minute visible satellite imagery from Friday, April 13, 2018 — Explosion of severe thunderstorms near and east of the dryline across the central/southern Plains this afternoon.
Goes-16 water vapor satellite image from Friday, April 13, 2018 — Powerful spring storm covering a large area from the northern Plains and upper Midwest to the central and southern Plains.
This was the radar image out of Sioux Falls, South Dakota earlier this afternoon. The yellow boxes on the map were severe thunderstorm warnings inside of a blizzard warning (red area) This plus the fact that surface temps were hovering around the freezing mark or a little above with a few severe thunderstorms occurring in that environment is quite amazing!
U.S. radar loop ending at 5:15 PM CDT, Friday, April 13, 2018
Forecast Discussion for northeast Minnesota and northwest Wisconsin
Mostly cloudy to partly cloudy skies. Gusty northeast winds, strongest near Lake Superior. Some snow and rain changing over to snow, chances for precipitation are greatest across southern portions of the Northland near and south of a line from Brainerd to Hurley — Precipitation could diminish during the night as northeast winds advect drier air into the Northland, pushing the precipitation shield further south. Not expecting much snow accumulation tonight for southern areas, maybe an inch or two at most.
Gusty northeast winds continue, strongest near Lake Superior. Should be dry most of the day, but snow is forecast to move into east central Minnesota and northwest Wisconsin Saturday afternoon or Saturday evening — This area of snow could shift farther north into the Twin Ports and North Shore areas late Saturday night, but confidence on that happening remains low. Northern Minnesota including the Iron Range and Borderland areas should stay dry Saturday and Saturday night.
Snow is expected to continue across northwest Wisconsin into east central Minnesota. Snow is also possible for the Twin Ports and North Shore, but again confidence on that occurring is on the low side.
Strong high pressure to our north will linger through the weekend while strong low pressure heads slowly E/NE out of the central Plains — The high to our north will continue to feed dry air south into the Northland while the low over the Plains tries to pull moisture north and up into our area. We’ve seen this setup quite a few times over the last month or so, and with each setup the high pressure/dry air have won out which kept the snow from the reaching Twin Ports.
Note: I’m staying conservative with my snowfall totals for this event for the Twin Ports and North Shore, well my confidence is somewhat higher that significant amounts of snow will eventually occur in northwest Wisconsin with the greatest amounts along the South Shore where lake enhanced snow will likely occur on Sunday. It’s possible that I will have to increase snow totals for Duluth and the North Shore, and it could be by quite a bit, I just don’t feel confident enough (yet) to do that given what has happened with similar setups we’ve seen during the last couple of weeks where the dry air wins out keeping the snow farther south from where models show it.
Lake Effect/Enhanced Snow Potential
Temperatures are forecast to become cold enough for some lake effect snow this weekend. Model forecasts show 850mb temps dropping to between -8 and -14C with lake water temps ~33F. A long fetch NE flow will be in place over Lake Superior through Sunday. Limiting factor right now is the amount of dry air in place, but if the snow from the storm is able to move this far north, then lake enhanced snow could develop along the North Shore and South Shore of Lake Superior on Sunday thanks to the increasingly colder temperatures and favorable wind direction this weekend.
It will be a cold weekend with well below average temperatures across the Northland. Lows tonight will be in the teens and 20s with single digits in extreme northern Minnesota. Highs Saturday and Sunday in the 20s and 30s. Note: Record or near record cold high temps are possible Saturday and Sunday for some locations in the Northland.
Link to Road Conditions
Average temperatures for Saturday for Duluth
Sunrise Saturday: 6:23 AM CDT
Sunset Saturday: 7:56 PM CDT