Marine Weather and Tide Forecast for Altoona, WI

DISCUSSION
Issued at 339 AM CDT Fri Apr 10 2026

Clouds are clearing from west to east early this morning. Areas of fog have formed over western MN following the clearing, and some of it may build east with the clearing for the next few hours before sunrise. The rest of the day will feature clear skies, light winds under high pressure. and mild temperatures in the 50s. The high will move off to the east tonight and southeasterly flow will begin to increase. Increasing clouds are expected overnight with moisture advection kicking in in earnest. Temperatures tonight will remain steady or slowly rise.

The rest of the period will be dominated by southwest flow and several disturbances embedded in it. A LLJ will strengthen Saturday with moisture transport increasing through the day.
Widespread showers are expected by afternoon, which despite the warm air advection, will keep temperatures steady in the upper 40s to lower 50s. Mid level lapse rates will remain poor, but a moist inversion around 850 mb should allow for a few hundred joules of elevated CAPE to develop in the afternoon and evening.
Scattered embedded thunderstorms are possible, but severe weather is not expected. As an area of low pressure approaches the eastern Dakotas late Saturday night, better low level warm air advection will work north and temperatures and dew points toward sunrise should rise to near 60. The shortwave/low pressure center will pass across northern Minnesota on Sunday.
The LLJ will veer east and should take much of the shower activity with it, but clouds and scattered showers may remain across WI for much of the day. Farther west, a dry slot will work east in the afternoon across the southern half of Minnesota. Clouds will clear as drier air aloft advects in and temperatures should respond quickly. 925 mb temps of +22 to +24C signal highs likely reaching the low to mid 80s. The stalling front, or the eastern extent of the dry slot, could allow for additional thunderstorm development late in the day in a narrow corridor along or just east east of I-35. However, forcing along the front is expected to remain weak. Also, areas west of the front should mix out and leave little CAPE, while areas east will remain moist, but likely capped from reduced surface heating. There is a conditional risk of thunderstorm development if enough low level moisture can remain where capping is less of an issue - likely along I-35.

A west-east oriented stationary front will linger across southern Minnesota and central Wisconsin Sunday night through Monday night. Very steep mid level lapse rates of greater than 8C/km will overspread the frontal zone Monday with MUCAPE potentially on the order of 1000-2000 J/kg. A few weak ripples in the southwest flow, a diffuse surface front, and an increasing 40 kt low level jet across Iowa later in the day may be enough to spark showers and thunderstorms late afternoon and evening. Capping may be an issue though depending how warm the boundary layer gets. Enough wind shear exists to organize storms, but the severe risk is considered conditional at this time. Regardless, another round of showers should develop across the region Monday night and continue at times through Tuesday night. The front is expected to remain nearby while another low pressure system passes across southern Minnesota or Iowa late Tuesday. The front will sink well south midweek, but upper ridging will linger as another system approaches from the northern Plains. Temperatures will warm again Thursday with increased chances for showers and thunderstorms returning to end the week.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
Issued at 641 AM CDT Fri Apr 10 2026

Areas of low clouds and fog developed across western MN overnight, but aren't impacting any of the TAF sites at the current time. There is a low chance it may move back into AXN briefly before lifting and scattering out after sunrise.
Northwest winds will ease and become light/variable tonight, then increase southeast Saturday.

KMSP...Back edge of the MVFR stratus is pushing east across the west metro and should clear MSP around 13Z. Northwest winds around 10 kts today becoming light and variable this evening, then southeast Saturday.

/OUTLOOK FOR KMSP/ SAT.. MVFR/-SHRA, chance IFR/-TSRA. Wind SE 10-15kts.
SUN.. MVFR/-TSRA early, then VFR. Wind S 15-20G30kts.
MON...VFR early, then chc MVFR/-TSRA. Wind lgt/variable to E 5-10kts.

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