Marine Weather and Tide Forecast for South Monroe, MI

DISCUSSION

Subjectively pleasant conditions this afternoon, especially by early March standards, feature ample sunshine and mild temperatures. Highs peak in the mid to upper 50s, aided by breezy southwest flow. Mixing depths remain fairly shallow for the rest of today as 40-45 knot flow (per KDTX VWP) stays trapped above 2 kft AGL due to an inversion layer. Still, 30-35 knot flow beneath should support several more hours of gusts in 30-40 mph range (near 45 mph within the typical Saginaw Valley enhancement area). Meanwhile, low pressure over Ontario with central pressure minimizing near 980 mb tracks eastward this evening, reaching James Bay by nightfall. This allows the pressure gradient to slacken slightly overnight, after the nocturnal inversion settles in late evening, which ends the threat of higher-end gusts.

Energetic belt of zonal flow aloft persists along the US/Canada border on Monday with another perturbation transiting central- southern Ontario. This surface reflection will be weaker than the aforementioned Ontario system, but a more southerly track acts to reinforce/reinvigorate the gradient over Southeast Michigan, aided by aggregate high pressure over The Southeast. Moisture prognostics indicate some degree of ThetaE convergence as PWATs double from 0.24 inches (per 08.12 KDTX RAOB) to over 0.50 inches tomorrow. However, any meaningful saturation should occur primarily in the upper levels marked by passing midday clouds. Temperatures climb aggressively into the upper 60s as 850 mb temperatures cross into positive double- digit (Celsius) territory. Familiar wind setup Monday with breezy southwest flow, gusting to around 30 mph during the diurnal cycle.

Stretch of dry weather concludes Tuesday as an elongated convergence axis sets up over southern Lower Michigan, amidst weak moisture transport. Growing NWP support exists for some light precipitation during the day, but less so in the way of meaningful QPF. Conditions change overnight as a cut-off upper low near the Baja Peninsula dislodges and quickly phases with an amplifying trough axis as it crosses The Rockies. This leads to an area of enhanced upper-level divergence as the composite wave works east across the Midwest.
Within the lower levels, increasingly confluent southwest flow draws Gulf moisture into the Great Lakes, aiding in the generation of rising CAPE. Showers increase in coverage late Tuesday night into Wednesday as synoptic ascent maximizes. Potential also exists for some thunderstorms during this time, but lapse rate integrity remains in question.

The surface low tracks through on Wednesday with a sharp transition in temperatures once the system's cold front works through. The cooling column will remain well saturated, which maintains shower activity, eventually transitioning to a wet snow by Wednesday evening. Not much accumulation expected into Thursday morning. The PV anomaly pivots through on Thursday with some lake streamers possibly leading to a bit of snowfall, but temperatures should exceed the freezing mark by the afternoon hours as shortwave ridging briefly passes through and stabilizes the lower troposphere. The active pattern carries into Friday with a highly ageostrophic wave set to dig through the northern Ohio Valley bringing potential for additional wintry and blustery weather to Southeast Michigan.

MARINE

Moderate to strong southwesterly winds continue through this evening with an occasional gust near gales possible over the central waters of Lake Huron. A lull in these stronger winds occurs early tonight as the first of northern Ontario lows departs for northern Quebec.
Southwesterly winds quickly restrengthen by early Monday morning as a second low slides along the far northern shore of Lake Superior.
Overall setup is similar to Sunday though with stronger warm advection resulting in more neutral to stable overlake thermal profiles. This further limits sporadic gale potential over central Lake Huron with 25-30kt gusts more likely (20-25kt winds over the rest of the region). A diffuse pressure gradient sets up across the central Great Lakes by late Monday as the secondary low reaches northern Quebec allowing winds to turn lighter through Tuesday.
Active pattern and stronger flow return by midweek as deepening Plains low pressure tracks over the central/southern Great Lakes.

HYDROLOGY

Widespread showers, and some thunderstorms, develop Tuesday night into Wednesday as a low pressure system tracks northeastward across Lower Michigan. Expected rainfall totals range from 0.75-1.25 inches by Wednesday evening, followed by a changeover to melting snow from north to south. Rises on area rivers are possible in addition to minor flooding, primarily for low-lying and poor drainage areas. Note the 12Z NBM 24 hour QPF QMD spread of around 0.50 inches for the 10th percentile, and over 2 inches for the 90th percentile.

CLIMATE

The record highest minimum temperature for Monday, March 9th.

Detroit: 53 Degrees (Set in 2016)
Flint: 59 Degrees (Set in 2016)
Saginaw: 55 Degrees (Set in 2016)

The record highest maximum temperature for Monday, March 9th.

Detroit: 71 Degrees (Set in 2016)
Flint: 72 Degrees (Set in 2016)
Saginaw: 67 Degrees (Set in 2016)

The record highest minimum temperature for Tuesday, March 10th.

Detroit: 46 Degrees (Set in 2016)
Flint: 45 Degrees (Set in 2016)
Saginaw: 43 Degrees (Set in 2021)

The record highest maximum temperature for Tuesday, March 10th.

Detroit: 70 Degrees (Set in 2021)
Flint: 71 Degrees (Set in 2021)
Saginaw: 69 Degrees (Set in 2021)

PREV DISCUSSION
Issued at 100 PM EDT Sun Mar 8 2026

AVIATION...

Dry and stable conditions this taf period will continue to promote clear skies across the lowest 5-7k ft. Some intervals of higher based cloud may funnel through at times, downstream of a cold front set to ease toward the region late Monday into Monday night. A firm southwest gradient will remain gusty through peak heating this afternoon, reaching in excess of 25 knots at times. Gustiness fades with sunset, with a transition toward low level wind shear overnight as passing low level jet strengthens winds off the surface.

DTW THRESHOLD PROBABILITIES...

* None



DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...Small Craft Advisory until 4 PM EDT Monday for LHZ421.

Lake St Clair...None.
Michigan waters of Lake Erie...None.