textproduct: Detroit/Pontiac

KEY MESSAGES

- Temperatures closer to normal and drier today, followed by additional rainfall late Thursday afternoon into early Friday morning.

- A strong cold front delivers gusty winds and much chillier conditions Friday, with a few showers in spots.

- Turing drier through the weekend with slightly warmer readings by Sunday.

DISCUSSION

Sprawling area of high pressure centered over the Dakotas is funneling cold air southward into the Great Lakes behind last nights cold front. The combination of cold air advection lake clouds and warm frontal clouds had lead to a very clouds day across the state. Temps have been slow to rise much into the 60s thus far so dropped forecast highs a few degrees. Lows tonight will fall into the 40s but will be tempered by the blanket of clouds so chances of 30s are slim.

Next chance of rain comes Thursday as a pair of strong systems, cutoff low from the 4 corners region and a deepening trough dropping out of Canada, phase over the Midwest before passing through the Great Lakes as an energetic positively tilted trough. Models are a little slower bringing the precip into SE MI, so pushed pops back til after noon. The center of the surface low was supposed to pass northeast through lower MI Thursday night, but as we get deeper into the window of CAMs, they are suggesting that there will be a secondary low farther east along the occluded front, staying just SE of MI, possible over Toledo. This doesn't do much for the expansive area of precipitation that will lift into the region along the warm conveyor belt, but it does bring convection into question, as this leading low looks to keep the instability gradient south of the area. CAPE values are coming in only around 100 J/kg or less in most model solutions. Will keep a mention of thunder in for now until we can more clearly define the area of convection, or placement of the surface warm front. QPF could range from a third to a half inch from Thursday afternoon through Friday morning.

Cold front will pass through early Friday pushing the brunt of the moisture out of the area but cold advection will initiate lake processes introducing additional moisture to any lingering wrap around moisture around the exiting low. In addition, cold advection will steepen lapse rates in the afternoon to around 10kft which will help scattered showers to develop. The deep mixing depths will also lead to a gusty day with winds solidly into the mid 20 knot range through the mixed layer throughout the day. Question is later in the evening as the upper level trough axis cross the area bringing a period of higher winds aloft into the 30-35 knot range. These winds could be mixed down briefly before we attempt to decouple so could see gusts increase around dusk for a few hours close to 40 mph.

Friday night will be colder as thermal trough at 850mb dips down to between zero to -5C with skies clearing as high pressure builds back in. Friday highs only into the 50s will help lows drop into the 30s with many locations across the northern CWA possibly seeing temps below freezing. Longwave ridge over the western conus and trough over the east will both be positively tilted heading through the weekend which will help delay the advancing thermal ridge back into the region. Highs Saturday will hold int he 50s before beginning to moderate Sunday back into the low 60s. Looks like ridging will hold over the region much of next week providing another lengthy stretch of dry weather.

MARINE

Moderate northwest wind continues this evening before weakening slightly and veering to easterly overnight as high pressure passes across the northern Great Lakes. An elevated wave field is forecast to clip the Lake Huron nearshore waters between Port Austin and Port Sanilac, and a Small Craft Advisory has been issued through tonight. Lighter wind takes on a southeast direction on Thursday ahead of a stronger low developing over the Midwest.

This low will bring active marine weather Thursday night through Friday as it strengthens while tracking from southern Lake Michigan to the Ontario peninsula. A 40 to 50 kt southwesterly low-level jet targets western Lake Erie Thursday night. Profiles show strong low- level stability during this window, which will hold the bulk of the momentum aloft. Will hold off on gale headlines for this brief feature as wind gusts are forecast to max at 25 to 30 kt. Numerous to widespread showers will accompany the system Thursday night.

A strong cold front will pass north to south across the region on Friday as the low departs to the east. Increasing instability and favorable fetch offer relatively high confidence to see northerly gusts to gale force on Lake Huron Friday afternoon and Friday night. Latest model data has trended slightly weaker with the wind field, so did cap the forecast gusts in the 35 to 40 kt range. A Gale Watch remains in effect for all of Lake Huron. Will continue to monitor the need to expand the watch into Lake St. Clair and western Lake Erie, but confidence remains too low at this time. Gusty northwest wind backs to west-southwest by Saturday as high pressure builds into the Ohio Valley.

PREV DISCUSSION

Issued at 223 PM EDT Wed Oct 14 2026

AVIATION...

A cooler post-frontal airmass remains in place across the terminal airspace this afternoon, preserving healthy coverage of MVFR stratocumulus cloud. Diurnal warming has helped lift BKN-OVC ceilings closer to 3 kft AGL, but forecast soundings indicate boundary-layer cooling should preserve some degree of lake-modified saturation amidst north-northeasterly low-level flow. Potential exists for ceilings to briefly/partially scatter out late this afternoon, possibly holding into the first half of the night. However, cloud bases should also trend lower overnight, and thicken. This could yield a return to MVFR, perhaps even below 2 kft, by early Thursday morning. Did TEMPO in a 1.5 kft AGL ceiling from 10- 13Z Thursday. Also, introduced a -SHRA mention after 17Z Thursday for all sites as the northeastern flank of an approaching low pressure system encroaches on Southeast Michigan. The surface low center should still be well off to the southwest, over the Mid- Mississippi River, by that time. Expect some time closer to 00Z Friday before visibility reducing rainfall and the chance for a rumble of thunder arrive.

D21/DTW Convection...No thunderstorms before 22Z Thursday. Low chance afterwards, once the heavier showers arrive Thursday evening, ahead of a low pressure system.

DTW THRESHOLD PROBABILITIES...

* Medium for ceilings at or below 5000 feet until this evening, then high starting very late tonight or early Thursday.

* Low for thunder, after 22Z Thursday.

DTX WATCHES/WARNINGS/ADVISORIES

MI...None. Lake Huron...Gale Watch from Friday morning through late Friday night for LHZ361>363-421-422-441>443-462>464.

Small Craft Advisory until 2 AM EDT Thursday for LHZ441-442.

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