Marine Weather and Tide Forecast for Stephenson, MI

SHORT TERM /THROUGH TONIGHT/
Issued at 302 PM EDT Mon May 12 2025

Hardly a cloud in the sky this afternoon with stout midlevel ridging over the Great Lakes and sprawling surface high pressure centered downstream over the Eastern Seaboard. On the back side of the surface high, persistent southerly flow continues to pump warm, dry air into the region. Temperatures this afternoon are climbing well into the 80s and even lower 90s in the western half of the U.P. At the same time, good old daytime mixing has seen dewpoints dropping into the lower/mid 30s in the western U.P. which is dropping RH well into the teens. Add to that widespread wind gusts around 20-25mph, and we have ideal conditions for fire growth and spread. Thus, a Red Flag Warning remains in effect across the western U.P. Meanwhile to the east, flow off of Lake Michigan is keeping things cooler.
Inland, temperatures are only rising as high as the mid/upper 70s, while nearer to the Michigan shoreline, some spots are struggling even to get out of the 50s. Still, with warm, breezy weather and a lack of recent rainfall, will want to remain cautious of fire spread across the eastern U.P. as well. Mind those local burn restrictions!

Winds taper off slightly overnight, with gusts falling below 20mph across most of the area. However, 20 mph gusts remain possible overnight in the higher terrain and where southerly winds are downsloping. Temperatures fall back only as far as the upper 40s to mid 50s across most of the area, with the downsloping spots across the western UP possibly still hovering in the upper 50s overnight.

LONG TERM /TUESDAY THROUGH MONDAY/
Issued at 302 PM EDT Mon May 12 2025

The beginning of the extended period will feature ridging over the Great Lakes, a weakening trough moving northward from the Mississippi Valley, and deeper troughing moving into the Rockies.
Southerly flow persists across our area, which will support another warm and dry day Tuesday; however, lighter winds and increasing moisture advection courtesy of the weakening low to our south will temper fire concerns somewhat compared to previous days. Still, afternoon RHs could dip as low as 20-30% across the interior west with high temps pushing 85-90 (70-80 elsewhere, 65-70 near Lake Michigan). And after previous critical fire weather days, drier fuels could support one more day of elevated wildfire potential.

Relief from the extended dry period and persistent fire weather concerns finally arrives this midweek into the weekend. The aforementioned western trough slowly moves through the Plains Wednesday through Thursday, with low pressure finally closing off sometime late Thursday into early Friday. This moves over the northern Great Lakes or into Ontario sometime Friday into Saturday while becoming vertically stacked. Ahead of this feature, a Gulf connection will allow a higher PWAT airmass to work in as early as Wednesday (ensembles favor PWATs in excess of an inch, or as much as 200% of normal). There remains some disagreement in the specifics on timing/track; perhaps the ridge remains a little more stubborn, slowing the eastward progression of this coming system. However, the general theme among ensemble and deterministic guidance is a couple rounds of widespread rainfall - and even some thunder! - sometime in the Thursday through Saturday period. Ensembles show several hundred to perhaps >1000j/kg of CAPE, along with a modest amount of deep layer shear (as much as 30kts), which could support some embedded stronger convection. Will not lock it in just yet, but it is worth monitoring with SPC showing a 15% chance of severe weather just to our south across WI. Meanwhile, a gradual cooling trend midweek onward will bring temperatures closer to and eventually slightly below normal. Latest NBM guidance suggests much welcomed rainfall amounts upward of 0.25-0.5" through Saturday (highest amounts in the late Thurs-Fri period), though this could be locally higher where convective elements provide a boost.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
Issued at 700 PM EDT Mon May 12 2025

VFR conditions continue through the TAF period. Winds will generally continue to lighten up from the south throughout the period, although we could see some gusts up to 20 kt by Tuesday afternoon. While there is a less than 50% chance for marginal low-level turbulence over CMX tonight, didn't include it in the TAF. Clouds begin to build back in over the central U.P. Tuesday afternoon.

MARINE
Issued at 302 PM EDT Mon May 12 2025

Very similar to yesterday, southerly winds continue to gust to around 20-30 kts across the central and eastern portions of the lake through this evening, with a few gale-force gusts not out of the question especially near the shorelines of the north-central and eastern UP courtesy of downsloping enhancement. Winds fall back overnight, with S wind gusts to around 15-20 kts across much of the lake Tuesday and Wednesday. Low pressure moves out of the Plains into the Upper Great Lakes later in the week, which could bring elevated winds above 25 kts Thursday onward.

MQT WATCHES/WARNINGS/ADVISORIES
Upper Michigan...
Red Flag Warning until 10 PM EDT /9 PM CDT/ this evening for MIZ001>005-009>011-084.

Lake Superior...
None.
Lake Michigan...
None.