Marine Weather and Tide Forecast for Tonka Bay, MN

DISCUSSION
Issued at 253 AM CDT Wed Apr 23 2025

Radar returns present over western Minnesota and moving east into east central Minnesota have scarcely reached the ground early this morning given relatively dry low levels. A few observation sites have clicked off light rain with some of the heavier bands passing through the forecast area, but generally very little precipitation is expected to reach the ground from these. As we progress through the day today, much of the forecast area will see mild conditions with clearing skies in the afternoon and highs reaching the upper 50s north to upper 60s and near 70 in central and southern Minnesota. While conditions will generally be fairly quiet over much of the area, shower and thunderstorm chances will increase through the day over south central Minnesota, as warm moist air overruns a stationary boundary lifting north through Iowa. This boundary will generally remain just to the south in Iowa, but weak forcing and trace amounts of MUCAPE along and north of the boundary will be conducive for shower and isolated storm development in southern Minnesota and western Wisconsin this afternoon and evening. That said, given the < 1000 J/kg of MUCAPE, the overall severe risk with any storms is low today.

A brief lull in precipitation is expected through the late afternoon and evening hours today, but we’ll see a resurgence in rainfall chances into the overnight hours as another surge of forcing and moisture attached to an approaching upper level shortwave and coincident surface low lift north into Iowa. This will bring more widespread precipitation chances to the forecast area through Thursday. With decent moisture transport surging north, PWATs will be boosted into the 1” to 1.2” range, which isn’t absurdly high for a heavy rain event but is roughly 175% to 200% of normal PWAT values expected over the forecast area in April. As a result, ensemble precipitation output shows mean QPF values around 0.75” to 1”, and a roughly 40 to 60% chance for precipitation greater than an inch in south central Minnesota and western Wisconsin, just southeast of the twin cities metro area. Unfortunately, as mentioned in previous discussions, there may be a cutoff to the Thursday precipitation on the northwestern edge of the system as high pressure pulls dry air and subsidence in on the back side of the system.
Therefore, those in western Minnesota may only see marginal amounts of precipitation before this occurs. Again, a minimal instability will inhibit severe chances, but occasional thunderstorms remain possible.

This precipitation lingers into the Friday morning hours, eventually departing east as the high pressure overtakes the rest of the forecast area, allowing dry conditions to set up through the weekend and give us a brief break from the precipitation. However, this break comes to an end as we get late into the weekend and into early next week as troughing builds in over the western conus, increasing moisture transport and forcing over the area. This will bring the return of shower and storm chances on Sunday, with a more pronounced system moving through the area Monday and Tuesday. The storm prediction center currently has a 15% risk for severe weather (slight risk) on Monday as this system moves into the area. More details on storms and severe weather will be provided in the coming days. The trough currently looks to pass through the Upper Midwest around Tuesday, bringing at least a brief period of dry weather and lower temperatures afterwards.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
Issued at 1155 PM CDT Tue Apr 22 2025

VFR will occur for the entire period with broken mid-level clouds near 10000 feet expected this morning and Wednesday evening. Calm/variable winds tonight will increase to 7-12 knots and turn west-northwesterly from west to east during Wednesday morning. These winds will last thru the afternoon before slowing to under 5 knots and turning more northerly Wednesday evening.

KMSP...North-northeasterly winds of 5-10 knots expected early Thursday morning.

/OUTLOOK FOR KMSP/ THU...-SHRA/MVFR likely, mainly P.M. Wind NE 10 kts.
FRI...VFR. Wind N 10-15 kts.
SAT...VFR. Wind SE 10-15 kts.

MPX WATCHES/WARNINGS/ADVISORIES
MN...None.
WI...None.