Marine Weather and Tide Forecast for Dearborn, MI

DISCUSSION

Broad area of surface high pressure over the southern/central conus will build eastward today and up through the eastern Great Lakes.
This will result in a backing wind becoming more southwesterly but will do little in terms of warm air advection as upper level troughing pulls increasingly colder air over the region with 850mb temps falling to near -20C. After rebounding finally back into the mid-upper 20s on Thursday, most locations will struggle to get out of the low 20s today. Should be a fairly quiet day overall in terms of snow but with the standard lake effect shadow off Lake MI still showing up on radar, models do hint at the southwesterly winds pushing the lake moisture across the state under the sharpening subsidence inversion. Looks at soundings, even though inversion heights will be around 4kft, the moist layer will clip the upper portions of the DGZ and with steepening low level lapse rates today, this should be enough to at least generate flurries for much of the area early this afternoon. Drier air building in from the southwest should help shut down the flurries this afternoon at least south of M59. We could sneak in a snow shower or two depending on if we can get any organized convergence band to sweep through the area.

Friday night through Saturday night will be one of those MI winter days with multiple chances for show showers, higher POPs, but with little QPF/snow amounts most likely. The next upper level trough is developing off to the NW which will pass through late Sat night into Sunday. Friday night a surface low start developing over the Midwest and pulls a warm frontal boundary up through SE MI. Isentropic ascent with left exit region dynamics aloft, should excite a band of light snow as it lifts through the region. This will be the first period where light accumulations will be possible but should not amount to too much as soundings show isothermal profiles around -10C up to 7-8 kft. Saturday afternoon could continue some flurries but should be quiet overall as we get a good punch of dry mid level air in the warm sector. But Saturday night the mid level trough axis and surface cold frontal reflection sweep southern MI. Should result in steepening low level lapse rates, frontal forcing, good saturation through the DGZ, etc...with westerly flow then setting up favorably for a period of lake enhanced snow showers.

Heading into the new work week, we get into a zonal mid level pattern with stronger northern stream up over Ontario with weaker strung out southern stream across the middle tier of the conus.
Temps return to around freezing for a couple days before the northern stream starts trying to dip back into the region which looks to brush SE MI with the colder air potentially.

MARINE

A weak convergence axis oriented from northwest to southeast across Lake Huron may return today, offering some additional lake effect snow activity. A ridge of high pressure attempts to build in from the deep south which backs local flow southwesterly throughout the day. Winds then increase tonight into Saturday as the next trough descends into the northern Great Lakes, tightening the surface pressure gradient. Favorable stability profiles and low-level jet energy drives gusts to near gales at times, but should be infrequent enough to preclude any gale headlines. Modest winds settle more westerly though the rest of the weekend with potential for widespread gales Sunday night into Monday.

PREV DISCUSSION
Issued at 1156 PM EST Thu Jan 23 2025

AVIATION...

The combination of lowering midlevel subsidence and the loss of daytime heating will decrease convective depths to 3.5 kft agl or less. There has been a decrease in stratus this evening. Cannot totally rule out scattered, rogue activity at any time tonight as supersaturation with respect to ice will exist in the near surface column that is within the Dendritic Growth Zone. Forecast soundings do show a drying of the near surface layer which should support a chance for low VFR to MVFR cigs. Daytime heating and remnant Lake Michigan convergence pushing into Southeast Michigan will bolster MVFR clouds Friday. The potential for some isolated to scattered snow showers will also exist.

DTW THRESHOLD PROBABILITIES...

* Medium for ceiling at/less 5000 ft tonight, high on Friday.

* High in precip type falling as snow.



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