Marine Weather and Tide Forecast for Ashland, WI

DISCUSSION
Issued at 308 PM CDT Thu Apr 24 2025

Fairly benign conditions have been observed across the CWA early this afternoon with varying amounts of cloud cover. Clouds have been advecting in from the south this afternoon ahead of an approaching shortwave trough. In addition to the shortwave approaching from southern Manitoba, low pressure will continue propagating eastward through the mid-Mississippi valley tonight into Friday morning. An area of light rain that has already developed within the baroclinic zone ahead of the shortwave trough axis will advect north into northwest WI late this afternoon into tonight. Total QPF from the system tonight into Friday will be around 0.5" or less.

Expect rain to come to an end across the CWA by Friday afternoon as the axis of the shortwave pivots through. Dry and mostly sunny conditions are expected Friday afternoon into Saturday as high pressure builds over the central CONUS. Model soundings from CAMs and the GFS show that a substantial dry layer will likely develop over the area on Saturday. With the potential for this dry air to mix to the surface, near-critical fire weather conditions may be a concern for Saturday as min RH drops to around 25%. Fortunately, fire weather concerns are somewhat mitigated by the relatively light winds that are expected under the high pressure.

Attention turns towards another active period of weather Sunday into Monday as a cutoff low over the Great Basin region rejoins the jet stream on Sunday and propagates towards the Midwest. Sunday will see rain shower chances arrive into the area as southerly flow provides strong WAA and ample moisture advection to the CWA This initial round of precipitation on Sunday will most likely be rain with the potential for isolated thunderstorms.

Thunderstorm chances ramp up late Sunday into Monday as steeper mid- level lapse rates in excess of 8 degC/km move into the CWA Moisture advection into the area will continue to be favorable, with PWAT by 12z Monday being as high as 1-1.4" (around the 97th percentile of NAEFS climatology). Expect this strong Gulf moisture advection to continue through the afternoon with high temps in the afternoon reaching the low 70s for the southern half of the CWA These warm temps combined with dewpoints reaching the low 60s and steep mid- level lapse rates will potentially increase MUCAPE in excess of 1000 J/kg for the southern half of the CWA This moderately favorable instability environment will occur in conjunction with strong 0-6km bulk shear of 50+ knots. At this time there is a fair amount of uncertainty regarding how far north the instability can reach and whether or not a sizable cap appearing in model soundings in the low-levels can be overcome. GEFS and EPS ensemble MSLP centers show a decent amount of spatial spread, which will have large implications on the placement of highest instability and the northward extent of possible severe convection. The Day 5 convective outlook from SPC still reflects a 15% chance for severe thunderstorms for areas along and south of US-2 on Monday. This will be a day to closely monitor as we head through the weekend and forecast confidence increases.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/
Issued at 639 PM CDT Thu Apr 24 2025

VFR covered the Northland early this evening with area radars showing widespread rain over southern Minnesota northeast into northern Wisconsin with some lighter rain/sprinkles further west over central to parts of northern Minnesota. Rain will be most widespread over northwest Wisconsin tonight tapering off to the west and north. Little if any rain will occur over far northern Minnesota. Ceilings will lower to MVFR over northwest Wisconsin and far eastern Minnesota overnight then they will rise west to east Friday. There are some indications that fog will develop tonight, including over far northern Minnesota. The clouds may limit how dense and widespread the clouds become. For now, we kept visibilities at MVFR at KINL.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
Issued at 308 PM CDT Thu Apr 24 2025

Light northeast winds will continue through the afternoon today.
Winds will generally maintain this direction through Friday night into Saturday morning with speeds of 5 to 10 kts across western Lake Superior. There will be some light rain along the South Shore zones tonight that will be exiting Friday morning. The next chance for hazardous conditions for small vessels won't arrive until Monday into Tuesday as winds increase along with chances for showers and thunderstorms.

For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.

DLH WATCHES/WARNINGS/ADVISORIES
MN...None.
WI...None.
MARINE...None.