####018005125#### FXUS63 KDTX 040707 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 307 AM EDT Sat May 4 2024 .KEY MESSAGES... - Morning fog and low clouds give way to a warm Saturday with highs in the low to mid 70s. - Scattered showers and possible non-severe thunderstorms this evening through Sunday morning. && .DISCUSSION... Despite the showers and clouds yesterday, high temperatures were able to sneak into the lower 70s across most areas. Extremely dry airmass noted with the 00z APX raob, and some of the mid level dry air has/will make inroads into southeast Michigan. However, cool northeast flow off Lake Huron and lingering low level moisture looks sufficient to saturate the low levels, and deep enough moisture (5+ kft layer) to potentially trigger stray light rain showers, especially toward the southern Michigan border, as some of the deeper moisture over Ohio attempts to work back north late in the day, ahead of a weak cold front moving through from the western Great Lakes tonight. With surface capes under 1000 J/kg today and the mid level dry slot, do not see EQL levels getting high enough to generate thunderstorms during the daytime, but a slight chance of non-severe storms appears warranted this evening/tonight with the modest height falls and the slightly negative showalter values tracking through. Stability will be on the increase 15-17Z Sunday as the front clears the State. Despite a fair amount of clouds today and the early morning fog, will allow high temperatures to reach into the mid 70s across most locations, based on the forecasted 925 MB temps of 17 C. Westerly confluent upper level flow Sunday night preceding an upper level ridge axis arriving early next week, supporting dry weather on Monday and likely during the daylight hours of Tuesday before a warm front brings widespread showers and possible thunderstorms Tuesday evening/night. && .MARINE... An area of high pressure centered over the region this morning is resulting in a weak gradient with light winds and waves across the region. Elevated dew points within the stable environment have resulted in areas of dense fog across Lake Huron and a Dense Fog Advisory is in effect until noon today. The gradient increases this afternoon as the high departs east, with wind organizing out of the southeast late today into tonight. A stalled front lifts north as a warm front tonight as a weak low moves from the upper Mississippi Valley into the northern Great Lakes. The system then sends a cold front through early on Sunday with a chance of showers and thunderstorms. Wind shifts to northwesterly behind the front Sunday afternoon, peaking at around 15 to 20 knots. High pressure then builds in to bring quiet marine conditions for Monday and much of Tuesday. The next warm front moves into the area late on Tuesday with stronger easterly flow developing ahead of it. && .PREV DISCUSSION... Issued at 1157 PM EDT Fri May 3 2024 AVIATION... The late afternoon and evening band of showers collapsed with the cold front while exiting into Ontario leaving the forecast up to clouds and fog late tonight through morning. Weak high pressure on an axis across northern Lake Huron and northern Lower Mi maintains a flow of cool and moist NE wind into SE Mi augmented by the cold water of Lake Huron. Just enough pressure gradient remains for wind speed in the 5 to 10 kt range favoring borderline LIFR/IFR stratus with a lighter fog component overall. The stratus plume expands westward from remnants of the cold front mainly affecting PTK, FNT, and MBS. NE wind direction aligned with the Ontario peninsula guards the DTW corridor from more than stray coverage. Wind veering SE directs clouds into western/northern Lower Mi during the morning while following a standard diurnal trend into a low end broken VFR ceiling for the afternoon. A stray shower is possible late in the day and closer to the interior of Lower Mi as Friday's cold front stalls in Ohio and then moves back northward as a warm front into Saturday evening. For DTW/D21 Convection... Thunderstorms are not expected late tonight through the morning. Very low potential for a thunderstorm with limited coverage by late afternoon precludes a mention in the forecast at this time. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms late afternoon and Saturday evening. * Moderate for ceiling 5000 ft or less late tonight and high by afternoon. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Dense Fog Advisory until noon EDT today for LHZ361>363-421-422- 441>443-462>464. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...SF MARINE.......TF AVIATION.....BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.