563 FXUS63 KDTX 162332 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 732 PM EDT Mon Jun 16 2025 .KEY MESSAGES... - Hotter and muggier Tuesday into midweek. - Showers and storm chances latter half of Tuesday. An isolated damaging wind gust possible in the strongest storms. - There is a Slight Chance for severe weather late Wednesday afternoon into Wednesday night along with a Marginal Risk for excessive rainfall for Wednesday and Wednesday night. && .AVIATION... Surface ridge axis with anticyclonic trajectory influence will persist across Southeast Michigan tonight. High based diurnal cumulus will dissipate the first hour or two of the forecast and VFR conditions are ensured overnight. There is some potential for light br/hz at daybreak Tuesday. Surface trough and convergence axis will approach southeast Michigan from the northwest Tuesday afternoon. Surface wind directions are expected to veer to the south southwest with notable midlevel thetae advection. The potential exists for isolated to scattered thunderstorms Tuesday afternoon 21z-24z. Low confidence exists in development and coverage and will limit mention to PROB30 groups at the Detroit terminals. For DTW/D21 Convection...Introduced a Prob30 group for thunderstorms 21-24z Tuesday. No severe weather expected. THRESHOLD PROBABILITIES... * There is a low chance for ceilings at or below 5000 feet Tuesday morning. * There is a low chance for thunderstorms between 21z-00z Tuesday. && .PREV DISCUSSION... Issued at 338 PM EDT Mon Jun 16 2025 DISCUSSION... Pleasant early summer day as high pressure centered over western Lake Huron has kept skies mostly sunny for the bulk of SE MI which helps to boost high temps toward the mid 80s by late afternoon. High pressure gradually departs to the east overnight as a warm front lifts through the region setting up southerly flow in its wake that begins to advect the airmass residing over the Midwest into lower MI. This keeps lows on the milder side as temps only bottom out in the low to mid 60s as dewpoints gradually creep above the 60 mark. Developing mid-upper troughing over the Plains induces strengthening deep layer southwest flow locally Tuesday fully advecting the Midwestern airmass into the central Great Lakes. 850mb temps reach 17-18C (up from 14C) allowing highs to reach well into the upper 80s. Surface Td`s climb into the upper 60s giving a muggier feel as well as pushing both SB/MLCAPEs to between 800-1200 J/kg by afternoon. Surface low pressure lifting out of Lake Superior into northern Ontario drags a cold front into southern lower MI by late Tuesday afternoon-evening which given the moisture/instability already in place, should be more than sufficient to initiate a NE-SW oriented broken line of convection over western/central MI. Given the orientation, the Saginaw Valley could see storms by mid- afternoon (~17-20Z) with this activity moving over the rest of the area between ~20-01Z. Shear is not impressive within the warm sector preceding the front as forecast soundings advertise a largely unidirectional, well-mixed wind profile below 700mb yielding bulk shear values at or below 25kts. That said, soundings also show an inverted V profile that supports near 1000 J/kg of DCAPE and the potential for downbursts under any of the more robust updrafts. Frontal boundary still expected to stall out directly over southern lower MI by late evening becoming the focal point for a couple more chances of potential convection. First of these chances comes Tuesday night from a potential remnant MCS coming out of the IA/IL area. 12Z CAM guidance remain divided on on both sufficient upscale growth to form this complex and its track. While these solutions advertise similar magnitudes of instability, they have significant differences in shear with bullish solutions like the HRRR having a stronger wind and subsequent shear profile to organize convection. Conversely solutions like the NSSL have weak wind/shear profiles resulting in weak organization and limited cold pool generation. Given south-southwest low level winds feeding this convection, track would be favored to stay over northern IL/IN. However a stronger outcome (like the HRRR) offers a chance for the northern edge of this decaying line of convection to reach SE MI as 400-700 J/kg of elevated instability will still be in place for areas south of the stalled frontal slope. Overall confidence is not high and chances aren`t particularly great given the favored southerly drift in storms; however, with lingering elevated instability and a frontal boundary in the area can`t rule out at least some scattered showers/storms overnight so will maintain lower end chance PoPs (~30%). Better chances for storms arrive Wednesday as surface low pressure rides along the front into lower MI late day. Stalled front is partially lifted north as a warm front in response to the approaching low allowing further moisture advection pushing dewpoints toward 70- for areas south of I-69. PWAT`s likewise increase above 1.5" and could cross the climo daily max for the day of 1.7". Starting with the severe aspect, SPC has maintained a Day 3 Slight Risk over the central portions of the state with Marginal Risk over the remainder of the area. These severe chances don`t arrive until late evening/overnight with the arrival of the surface low and its accompanying 50-60kt LLJ. Main concern on whether or not severe storms can occur is the late arrival of the low as a sizable subset of mid-range models are not showing it overhead until between 00-06Z, which reduces the amount of remaining diurnal instability available (falls from 1500 toward 700J/kg over this timeframe) in addition to greatly decreasing the likelihood for storms to remain surface based the later it arrives. Another point of concern is that there are chances for scattered showers and storms during the day Wednesday along the front that could decrease the degree we destabilize and limit overall max instability. Should the earlier arrival solutions (ie evening) occur, damaging wind gusts would be the primary hazard with a few tornadoes possible given the warm front lifting over the area as the triple point tracks over or near SE MI increasing low level curvature in hodographs. In addition to the severe threat, the Gulf moisture feed pushing PW values near daily records offers heavy rain/flooding potential with storms Wednesday. Soundings also show warm cloud depths of 12-15kft throughout the day increasing precip efficiency with any preceding showers/storms along the front daytime Wednesday as well as convection with the low itself late day. One additional point of concern that will need to be watched in coming model cycles is some signal amongst model solutions supporting training convection during the day along the frontal boundary before the arrival of the low which could boost overall QPF. MARINE... High pressure still influencing the region as it continues to drift eastward today. The shift in position has resulted in a warmer southerly flow over the waters with winds generally under 15 knots. Slight increase in winds Tuesday behind a warm front lifting through the area but still expected to be under 20 knots. The offshore flow should also minimize any increased wave potential. An unsettled pattern follows through the rest of the week as a series of low pressure systems track through the region. Showers and thunderstorms will be possible each day with potential for strong storms on Wednesday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....CB DISCUSSION...KDK MARINE.......DRK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.