Marine Weather and Tide Forecast for Ephraim, WI

DISCUSSION
Issued at 502 AM CDT Wed Apr 30 2025

Low clouds formed off of Lake Michigan and expanded westward overnight, which has left much of the forecast area under a low cloud deck. Easterly winds have also held up, contributing to the expansion of these clouds. Therefore, temperatures have remained a little warmer than expected in the mid 30s for most locations as of 09Z. Places where skies were still clear (Land O' Lakes and northern Door County) were cooler and had calm winds.

It took models a bit to pick up on this cloud trend, mainly followed the HRRR and NBM for cloud coverage today. Low clouds continue to hang around through midday, and then scattered out as winds veer to the south. This is quickly followed by increasing high clouds ahead of the next weather system. So, looking at a partly to mostly cloudy sky today, which may have a slight influence on temperatures. But, the late day warm advection and any breaks in the clouds should help. Forecast highs are in the upper 50s and low 60s, and cooler along the lake shore in the mid 40s to low 50s.

Focus shifts to a few rounds of rain from tonight through Friday.
There is a shortwave/sfc low moving up from the southwest, quickly followed by one from the northwest. Still some timing and track differences, but either way overall impacts will be low.
First low approaches tonight and moves south of WI on Thursday.
Some models have pulled this farther south, leading to little precip getting into the GRB forecast area; while others still bringing in light rain, at least for the southern half. Slowed down arrival of PoPs until around or after midnight which continue through Thursday. Just as this system departs a shortwave/low moves in from the northwest, bringing another round of light to moderate Thursday night into Friday morning. With some lingering moisture and lift possibly into Friday afternoon--especially across northern WI. Rainfall totals from 12AM Thursday through 7PM Friday range from ~0.25 to 0.50 inches, which does not trigger any flooding concerns. Cannot rule out some embedded thunder on Thursday with a few spots of 100-200 J/kg of CAPE present, but overall thunder chances are low and severe weather is not expected.

High pressure builds in for the weekend leading to pleasant weather conditions. Dry weather is expected from Saturday through at least Monday, with high temps in the 60s on Saturday, and 70s for most from Sunday-Wednesday.

AVIATION
for 18Z TAF Issuance Issued at 1151 AM CDT Wed Apr 30 2025

Low clouds have all but cleared out across the region late this morning, with high clouds streaming in from the southwest. VFR conditions are expected the rest of this afternoon and into this evening. Light rain will then arrive later tonight and continue into Thursday. Conditions are expected to drop to MVFR, with some IFR possible at times on Thursday with the rain showers.

GRB WATCHES/WARNINGS/ADVISORIES
None.