A broad trough of low pressure stretching from west-central Canada to the Southern Plains Wednesday morning will advance slowly eastward through Thursday — The main surface low with this system will remain over the Southern Plains, and well south of the Northland, but a broad southerly flow out ahead of an eastward moving trough will pull moisture northward up into our area which will lead to some rain at times from Wednesday morning into Thursday.
The highest rain amounts in the Northland with this event are expected to be over western portions of the area, with lesser amounts of rain expected for the Arrowhead and for much of northwest Wisconsin.
There will be a good supply of moisture for this system to tap into as precipitable water ranges from around 0.90″ to 1.20″ across much of the Northland for Wednesday into early Thursday.
12z HREF model precipitable water forecast valid 1 PM Wednesday, October 27, 2021.
We could see a few showers develop over parts of the Northland overnight tonight, but chances for rain showers increase during the day Wednesday, although coverage of this rain during the day should remain on the scattered side.
A more widespread rain is possible from Wednesday evening through Thursday morning, with this rain diminishing from west to east Thursday afternoon-evening the way it looks now.
18z NAM 3km model simulated radar forecast valid from Midnight tonight to 1 AM Friday.
Rainfall amounts continue to look highest over western portions of the Northland (black outlined area on map) with amounts of 0.75 to over 1″ possible through Thursday. Rain totals taper off farther east, with amounts generally in the quarter to half inch range expected including in the Twin Ports. Even lower rainfall amounts are expected over the Arrowhead of Minnesota with trace to 0.10″ amounts.
It should be noted, however, that the GFS model continues to show a lot less rain in northeast Minnesota including in the Twin Ports, and also in northwest Wisconsin for the Wednesday-Thursday time frame, with amounts of only a trace to around 0.15″.
A few thunderstorms could develop in parts of the Northland on Wednesday as we see elevated CAPE increase to a few hundred J/kg, but severe weather is unlikely in our area, but don’t be surprised if you hear a rumble of thunder in parts of the area on Wednesday.
18z HRRR model Most Unstable Cape forecast thru 7 PM Wednesday.
Highs in the mid 40s to low 50s are expected in northeast Minnesota and northwest Wisconsin for Wednesday and Thursday before a warmup occurs Friday and Saturday, those days will feature widespread 50s for daytime highs in the Northland.
Colder risks continue to show up in long range model data for next week with a few days of highs in the 30s to lower 40s possible in the Northland, this is thanks to an upper level ridge which is forecast to develop over western Canada, while an upper level low/trough sets up east of that ridge over central/eastern Canada, this will help usher in a chillier air mass as the flow aloft becomes northwesterly for early next week.
Along with the cooler temps could come some scattered snow showers and flurries over parts of the Northland early next week, but no significant snow events are on the horizon at least through most of next week the way it looks now.