


Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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039 FXUS63 KDTX 132220 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 620 PM EDT Mon Oct 13 2025 .KEY MESSAGES... - A dry cold front moves through the area Tuesday leading to cooler temperatures Wednesday. - There is also an increasing probability of rain Wednesday morning, currently at about 30 percent. - Dry weather and normal mid October temperatures resume during the late week. && .AVIATION... A cold front on pace to sag across the region tonight. Moisture remains limited with this frontal passage, leaving simply some pockets of higher based VFR cloud at times. Assuming a greater window of open sky exists within a weakening gradient, this will again bring potential for some areas of fog and/or very low stratus during the pre-dawn hours. Less favorable conditions than recent nights as low level flow no longer carries an added boost off the lakes, so confidence in occurrence at any one location remains quite low. Forecast will continue to highlight a window between 09z and 13z for some reduction of visibility. Rapid improvement in visibility thereafter, leaving a standard expansion of VFR diurnal cu for Tuesday afternoon. For DTW/D21 Convection...No thunderstorms through the taf period. DTW THRESHOLD PROBABILITIES... * Low for visibilities aob 1/2 sm or ceilings aob 200 ft early Tuesday morning. * Low for cigs at or below 5000 ft Tuesday. && .PREV DISCUSSION... Issued at 334 PM EDT Mon Oct 13 2025 DISCUSSION... Healthy diurnal cumulus field observed via visible satellite this afternoon. Localized clear pockets reflect where widespread fog/low stratus lingered this morning and disrupted the mixing process. These areas are running a few degrees cooler than surrounding obs, but still result in a pleasant fall evening with temperatures in the upper 60s-low 70s. Satellite also shows a continuous cloud band from northern Ontario to Texas, marking the frontal zone that extends from the occluded Hudson Bay low. This front has made little eastward progress today, but will eventually get redirected equatorward across Lower Michigan tonight/Tuesday as a surface high expands across the northern tier states. Radar returns have decreased throughout the day with the influx of a dry slot aloft and bifurcation of low level moisture transport. This is on par with model trends, which support a dry fropa Tuesday. Remnant cloud cover is expected to accompany the frontal passage, but should be transient/shallow enough to allow for some patchy fog development Tuesday morning. Cold advection will not peak until Wednesday, but still expect to see a thermal gradient from the Saginaw Valley (highs in the upper 60s) to the Ohio border (highs in the mid 70s). Conditions will be strongly influenced by the evolution of the upper level ridge as the week wears on. The ridge will transition from its current broad/flattened state into an amplified trough-ridge pair by the end of the work week as northern stream waves carve into New England. Locally, this results in mid-level height falls and a southern shift to the jet stream that directs weak forcing across the Great Lakes Wednesday morning. Moisture struggles to stay in tact as it encounters the much drier surface high over the Great Lakes. This high effectively stalls theta-e advection well west of the state to limit QPF locally to a few hundredths of an inch Wednesday morning. The thermal gradient follows a similar pivoting pattern, with SE MI in the path of the thermal trough. Temperatures on Wednesday only make it into the low 60s as a result. Dry weather follows to close out the work week, followed by an unsettled pattern this weekend as the upstream theta-e ridge releases eastward in tandem with strong low pressure. Majority of ensemble members generate measurable 24-hour QPF amounts Friday-this weekend with a general warming trend anticipated. MARINE... Mostly dry cold front tracking through the Central Great Lakes this evening. Northwest winds will gradually increase tonight and Tuesday behind the front as colder air slowly filters into the region. The coldest air will arrive early Wednesday morning, as 850 MB temps drop into the low to mid single numbers. Winds will be out of the northeast at this time as large high pressure builds through the northern Great Lakes. With northerly sustained winds around 20 knots Tuesday night, the prolonged long fetch will likely be enough to build waves at or above 4 feet over the southern Lake Huron Basin. Winds to then become light and variable to end the work week as the high pressure system becomes fully entrenched. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Small Craft Advisory from 5 PM Tuesday to 5 PM EDT Wednesday for LHZ421-441>443. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....MR DISCUSSION...MV MARINE.......SF You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.