Marine Weather and Tide Forecast for Grosse Pointe Park, MI

AVIATION

A lot of variability to the ceilings this morning as low pressure continues to slowly rotate north into Michigan today. Will maintain the greater prevailing MVFR ceilings with intervals of IFR through this morning. VSBY reductions should be limited this morning as denser fog signal did not materialize. Do not expect ceilings to improve rapidly this morning, but it does appear conditions will improve to predominately VFR for the afternoon. This afternoon will see a greater chance for showers while diurnal instability will also support some isolated thunderstorms this afternoon into the evening.

For DTW/D21 Convection... An isolated thunderstorm remains possible this afternoon but with low predictability on timing and location.

THRESHOLD PROBABILITIES...

* High for ceiling aob 5000 feet through today.

* Low for ceiling/visibility below 200 ft and/or 1/2 SM this morning.

* Low for thunderstorms this afternoon and evening.

PREV DISCUSSION
Issued at 353 AM EDT Wed May 14 2025

DISCUSSION...

Minimal convective coverage is seen on radar this morning compared to last afternoon/evening as we move into the diurnal minimum.
Atlantic moisture continues to stream into the Great Lakes on the eastern periphery of a cut off upper low, which has resulted in chaotic cloud cover over the forecast area overnight. Areas where clearing has taken place (generally south of I-94) have started to see shallow fog development, whereas northern locations hang on to the existing stratus deck through much of the morning before breaking this afternoon. Convective coverage reinvigorates this afternoon in the peak heating window with a similar flavor to yesterday, although boundary layer conditions allow MLCAPE to build above 500 J/kg. Scattered pulse-type showers and thunderstorms will thus be possible this afternoon-evening.

The upper level circulation that has governed conditions for the past several days will dissolve into the mean flow pattern today and tonight. This allows existing easterly winds to gradually veer, eventually settling out of the southwest by Thursday morning which kickstarts a period of warm advection. H850 temperatures rise from an average 13 C for the past couple of days into the upper teens by Thursday. Daytime highs thus exhibit a marked warming trend Thursday, into the upper 70s to low 80s.

A second upper low is noted on satellite imagery over the Intermountain West this morning. This low will pivot and take on a negative tilt as it tracks toward the Upper Midwest Thursday, driving an existing thermal ridge/warm sector into the Great Lakes. While boundary layer conditions become increasingly warm/unstable, a mid- level dry slot works to cap the environment for most of the day. It is not until the arrival of the system's cold front late Thursday night (roughly 11p-3a) that convection will eventually reach SE Michigan. Convective initiation is expected to occur Thursday evening over Wisconsin and grow upscale before crossing lower Michigan after dark. By the time storms reach SE Michigan, they will encounter not only the existing capping inversion but also a nocturnally cooled boundary layer. Still, there will be plenty of elevated instability to work with (MUCAPE around 2500 J/kg and mid level lapse rates over 7.5 C/km), which combines with strong/curved shear profiles to favor large hail as the primary threat Thursday night. Should storms maintain surface-based inflow, damaging wind gusts and/or an isolated tornado cannot be ruled out. SPC has designated a Slight Risk for Thursday night across SE Michigan.

Despite the cold frontal passage Thursday night, temperatures on Friday rebound into the low 80s ahead of a cooler weekend as the upper low meanders into the central Great Lakes. Unsettled conditions persist Friday-Saturday as the low wraps existing moisture and nebulous forcing overhead.

MARINE...

A weak pressure gradient will maintain lighter southeast flow today with continued bouts of isolated to scattered showers and some embedded thunderstorms. The moist conditions over the cooler waters of Lake Huron also will bring periods of fog with visibilities ranging to or below 1 nm. Some improvement to visibilities will be likely through the afternoon and evening before renewed chances for reformation returns through tomorrow morning.

A warm front remains on schedule to pass over the Great Lakes late tomorrow night into Friday, which will veer wind direction to the southwest while gradually increasing wind speeds. Better organized thunderstorm activity will be possible along the warm front, which includes the potential for embedded stronger storms capable of producing wind gusts to or in excess of 40 knots.

DTX WATCHES/WARNINGS/ADVISORIES
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.