textproduct: Detroit/Pontiac

KEY MESSAGES

- The next round of precipitation is on schedule for tonight and Wednesday. All rain is expected with a chance of freezing rain north of M 46.

- Mild temperatures persist through Thursday.

- A rain/snow mix moves in by Friday followed by a temperature drop back toward mid/late February normals this weekend.

AVIATION

An expansive region of fog extending across Lakes Huron, St Clair, cntl Lake Erie and portions of southern Ontario is within a strongly stable boundary layer capped by a deep inversion. Weak low level easterly flow has been attempting to drive the fog inland. The inland extent this afternoon will be limited by diurnal heating. This suggests most of the terminals will have MVFR or VFR conditions this afternoon. The exception may continue to be KDET due to its proximity to Lake St CLair and KMBS due to its proximity to Saginaw Bay. Low level east-southeast flow will increase this evening as a warm front organizes just south of metro Detroit. This will likely drive the fog and low clouds off the lakes back across the rest of the terminals. Deep layer moisture advection within an inbound upper short wave will support widespread rain during the overnight, with the warm front eventually lifting north of metro Detroit late Wed morning. Prevailing LIFR conditions in rain and fog is thus expected through the night and into Wednesday morning.

For DTW...The fog extending into metro Detroit extends back to north central Lake Erie. Diurnal mixing will offer some degree of improvement in conditions this afternoon. The onset of nocturnal cooling this evening is however likely to drive the fog and lower clouds back into metro airport.

DTW THRESHOLD PROBABILITIES...

* Low in ceilings aob 200 ft and/or visibilities below 1/2SM overnight and Wednesday morning.

* High in ceilings aob 5000 feet tonight and Wednesday morning.

* High in precip type as all rain tonight.

* Low in thunderstorms overnight and Wednesday morning.

PREV DISCUSSION

Issued at 1042 AM EST Tue Feb 17 2026

UPDATE...

Main item for this morning update is the issuance of a new Dense Fog Advisory as dense fog off Lake Huron pushes inland under a light east wind. Will monitor for any improvements for greater inland areas of the Thumb shoreline counties into Bay county, but immediate shoreline areas may see fog hold on through much of the day. If no real improvements occur, it will be possible all or parts of the Dense Fog Advisory may get extended into tonight.

PREV DISCUSSION... Issued at 353 AM EST Tue Feb 17 2026

DISCUSSION...

A unique fog scenario is unfolding within a weak cold front/trough that was initially low cloud-free for much of the night. This allowed radiational cooling in and near the surface trough where mid to upper 30s Td pooled resulting in a large area of dense fog from the northern Thumb to Port Huron, Flint, and the northern suburbs of Detroit. A Dense Fog Advisory is in effect until 10 AM for this area. Some of the fog could leak south toward the I-94 corridor, however the effect of mid and high clouds is holding surface T up in the lower to mid 40s. Plan to monitor trends there and also northward toward the Tri Cities.

The cold front settles and stalls just south of the Ohio border this afternoon, and remains precipitation-free as the 500 mb ridge axis moves overhead and stabilizes the frontal zone. It will be dry but there will be a substantial cloud component within the low to mid levels of the frontal zone all across southern Lower Mi. Increasing easterly surface and boundary layer wind builds the fog into a stratus layer, especially north of I-69, while mid and high clouds continue to thicken over the entire region this afternoon. The clouds and wind direction combine to knock temperatures down 5 to 10 degrees compared to Monday. Highs today range from the upper 30s along the Lake Huron shoreline and Saginaw Bay to the upper 40s interior west of I-75, a good representation of the wind direction influence across the area.

The front awaits activation by the large low pressure system that is on schedule to organize across the northern to central Plains this afternoon. The Pacific Coast 500 mb low is well on the way through the Rockies this morning accompanied by a 170 kt 250 mb jet, both of which will induce strong lee side cyclogenesis across the Plains this afternoon. Organization of the surface system includes a strong low level jet spreading eastward along the front that has access to Gulf modified air for transport into the low to mid levels of the frontal zone over the Great Lakes. The strong moisture transport quickly produces an expanding pattern of showers on the leading edge and within the advancing theta-e ridge to near widespread coverage by midnight. Given the limited temperature rebound today, readings are expected to drift down slightly below freezing this evening in the northern Thumb and northern reaches of Midland and Bay counties making that area vulnerable to a few hours of freezing rain. This forecast update increases the freezing rain footprint in the northern Thumb where easterly wind brings in colder air unobstructed from Ontario across a mostly frozen southern Lake Huron. There is greater coverage potential but still a relatively short time window for icing to occur as even there readings are projected to quickly rise above freezing after about 3 AM tonight. The temperature trends will be monitored closely for potential of anything more than current the current light glaze of icing expectation.

The peak of the rain event occurs late tonight and early Wednesday as the 850-700 mb frontal zone surges south to north across Lower Mi. Interesting that elevated instability was adequate for a few thunderstorms in northern Lower Mi yesterday afternoon which points to even greater potential as model data takes 850 mb LI negative during peak moisture transport and on the leading edge of the mid level dry slot. This dry slot brings a quick end to the rain by early Wednesday afternoon while the warm front/occlusion stalls in the vicinity of the I-69 corridor. The frontal position allows the warm sector to build north of the Ohio border up through metro Detroit where highs in the lower 60s remain in reach while readings could be limited to the upper 30s again in the northern Thumb.

The Midwest to Great Lakes system stalls and begins to fill Wednesday night and Thursday as the next larger scale wave breaks away from the Pacific Coast long wave trough. This system moves inland and into the central Plains Thursday on a track into the western Great Lakes Thursday night and Friday where it merges with the leftover frontal zone from the Wednesday system. Longer range model runs indicate a strong occlusion over Lower Mi that favors rain at onset changing to a rain/snow mix as the system pivots through the area Friday and exits Friday night. Temperatures then drop back toward normal mid/late February readings for next weekend.

MARINE...

The Great Lakes reside within a deformation zone this morning, leading to split flow with northwest winds across Lake Huron and southwest winds across Lake Erie. Low pressure is already well organized and moving into the Plains at issuance, which will organize winds out of the east through the day as it moves closer. Elevated portions of the system's warm front expand north across the Great Lakes Wednesday, drawing the low level jet northward but leaving enough depth to the cold air to mix a few thousand feet off the deck. Guidance continues to support a threat for gale force wind gusts daytime Wednesday across northern Lake Huron where the cold air is deepest. There is enough confidence in the setup for a Gale Warning upgrade with the early morning forecast issuance. Marine areas south of Sturgeon Point likely see rain with this system, with increasing chances for wintry mix to the north. Next round of elevated wind potential comes Friday as another low pressure system impacts the Great Lakes region.

HYDROLOGY...

Widespread rain moves in ahead of a strong low pressure system and warm front tonight and Wednesday. Moderate probabilities for 0.25" to 0.5" of rain are expected south of I-94 and low to moderate probabilities for 0.5" to 0.75" to the north across the rest of SE Michigan. The rain will occur on top of a melting snowpack that had a Snow Water Equivalent analysis ranging between 0.5" to 1". The combination of rain and snow melt on frozen ground may lead to rises on area streams and rivers. Ponding of water on roads is also possible, especially where drains could be blocked by snow and/or winter debris.

DTX WATCHES/WARNINGS/ADVISORIES

MI...Dense Fog Advisory until 4 PM EST this afternoon for MIZ048-049-054- 055-063.

Lake Huron...Dense Fog Advisory until 10 AM EST Wednesday for LHZ421-422-441>443- 462>464.

Dense Fog Advisory until 10 PM EST this evening for LHZ361>363.

Gale Warning from 4 AM to 4 PM EST Wednesday for LHZ361-362.

Lake St Clair...Dense Fog Advisory until 10 AM EST Wednesday for LCZ460.

Michigan waters of Lake Erie...None.