6:58 PM Tuesday, April 4, 2023
Snow, sleet, freezing rain/freezing drizzle, areas of blowing snow, a few thunderstorms, and oh some lakeshore flooding, this storm is bringing just about everything to the Northland.
Highest snow totals continue to favor far northwest portions of the area (International Falls) while areas to the south/east see more of a wintry mix of snow, sleet and freezing rain, and some of this freezing rain could be heavy at times leading to significant amounts of ice accumulations over a small area of northwest Wisconsin and possibly west into far eastern Minnesota including the Twin Ports.
Very strong northeast winds with gusts of 50 to 65 mph will continue near Lake Superior and in Duluth tonight until around 7-9 AM Wednesday. These high winds alone could cause a few power outages and also produce some tree damage.
A higher potential for more widespread tree and power line damage including widespread power outages exists for those areas that end up seeing higher amounts of ice accumulation (around a quarter inch or more)
FREEZING RAIN/ICE ACCUMULATION POTENTIAL
There remains some uncertainty when it comes to the amount of ice that could accumulate in parts of northeast and east central Minnesota and parts of northwest Wisconsin tonight through about mid-morning Wednesday.
Some of the uncertainty is on where thunderstorms develop tonight and where do those storms track once they develop. A few of the models have those storms moving farther west impacting eastern Minnesota and the Twin Ports, but there’s a few others that keep most of those storms in northwest Wisconsin.
Where those thunderstorms occur will likely be where the greatest amounts of icing will be tonight since the storms will contain brief but heavy downpours, and with temps around 28 to 31 degrees, the rain that falls should instantly freeze once it hits the ground. Outside of those thunderstorms, precipitation intensity should be lighter whether it takes the form of freezing rain or freezing drizzle.
It’s a low probability outcome but if the convection (thunderstorms) stays east of Duluth tonight, then the Twin Ports area could escape the brunt of the more significant ice accumulations, again this is a low probability, but certainly is not out of the question.
Like I’ve done over the past few days here are a few of the ice accumulation forecasts from the various computer models.
Totals for Duluth
Euro: 0.19″
Euro Ensemble: Low end of 0.10″, high end of 0.39″
NWS Blend of Models: 0.22″
SNOWFALL FORECAST
Here’s my updated snowfall forecast thru 7 PM Wednesday.
The amounts on the map are on top of the snow that has already fallen, so these would be additional snowfall amounts.
Duluth: I’m only expecting an additional trace to 2 inches of snow for the rest of this storm as precipitation should fall mainly as sleet, freezing drizzle/freezing rain through Wednesday morning before we see some snow showers redevelop on the backside of this storm Wednesday afternoon and night.
0.6 inches of snow fell at the National Weather Service in Duluth, MN today (thru 4 PM) this brings the seasonal snowfall total for 2022-2023 to 129.6 inches which makes it the 4th snowiest winter on record. Still need another 5.9 inches of snow to break the all-time snowiest winter on record of 135.4 inches set in 1995-1996. This storm won’t be the one to do it.
LAKESHORE FLOODING
Lakeshore Flood Warning until 10 AM Wednesday.
15 to 20 foot waves combined with very strong and prolonged northeast winds will result in piling up of water in the Twin Ports area which will likely result in coastal flooding.
Flood waters may affect sidewalks and parking lots near Lake Superior including Canal Park.
Roads and portions of roads may be closed due to the flooding.
SEVERE THUNDERSTORM POTENTIAL
There is a Marginal Risk (level 1 out of 5) for severe thunderstorms tonight in parts of northwest Wisconsin (dark green area on map) Large hail to quarter size or 1″ in diameter is the main severe weather threat.
Note — There is also a chance for some minor flooding over portions of eastern Minnesota and northwest Wisconsin tonight affecting portions of Pine, Burnett, Washburn and Sawyer Counties, this is due to the potential for rainfall totals of 0.50 to 1″ on top of the snowpack which contains near record levels of water. Minor flooding could develop across the St. Croix and Chippewa river basins.
The lighter green area is where isolated non-severe thunderstorms are possible tonight.
European computer model radar forecast through 7 PM Wednesday.
Snow (blue)
Mix (orange and pink)
Rain (green)
Strong high pressure over Hudson Bay with strong low pressure over the central Plains today, this is a perfect setup to get very strong northeast winds near Lake Superior due to the tight pressure gradient between the high and low, but also due to the very big temperature difference between here and Iowa.
A strong upper-level low over Wyoming this afternoon along with an upper-level trough over the Rockies will continue to lift northeast through the northern Plains and upper Midwest over the next 24 hours.
As is often the case with these major storms we have a very potent temperature gradient with 850mb temperatures of -8C over central North Dakota to +18C over central Iowa.
Very strong warm air advection (red colors) is occurring this afternoon ahead of the low over the central Plains with strong cold air advection (blue colors) immediately behind the low.
At the surface, temperatures were in the 80s to around 90 degrees late this afternoon over southern Iowa with teens and 20s in North Dakota.
The convective nature of the precipitation which brought bursts of heavy snow and sleet and even a few thunderstorms to parts of eastern Minnesota and northwest Wisconsin this afternoon continues to lift farther north into the Arrowhead and in its wake, we’re seeing a widespread area of mid-level dry air (yellow colors) which is causing a lull in precipitation intensities in east central Minnesota and northern Wisconsin as of 5 PM today.
Goes-16 Mid-Level Water Vapor Loop from Tuesday, April 4, 2023 (loop time ends 5:24 PM CT)
Tim