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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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187 FXUS63 KDTX 261102 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 702 AM EDT Wed Jun 26 2024 .KEY MESSAGES... - Scattered showers and a few strong thunderstorms around today, especially south of M-59. - Cooler and less humid air moves back into the area tonight and lasts through early Friday. - Showers and strong thunderstorms return Friday night into Saturday. && .AVIATION... A weak cold front paused southward progress in central Lower MI during the night allowing an area of IFR fog to form in the humid air south of the front. The fog affected FNT and MBS before high clouds thickened leading up to sunrise and now follows a standard trend of visibility improvement during the morning, especially as SW wind picks up slightly. Southward progress of the front is further delayed today by a wave of low pressure moving in from the Midwest. Clusters of light rain showers moving in from IA/MN/WI are a tracer for the low pressure system which appears strong enough to leverage the front for additional coverage of activity this afternoon. A prevailing VFR shower with a thunderstorm prob still looks good during the mid to late afternoon instability peak which then fades by mid evening. The cold front exits south into the Ohio valley this evening followed by a cool northerly boundary layer wind tonight. Borderline VFR/MVFR ceiling is likely for a few hours given a boost of moisture from Lake Huron late tonight into Thursday morning. For DTW/D21 Convection... Showers increase coverage over D21 as the day progresses. An isolated thunderstorm is possible along the YIP- DTW-DET corridor from mid afternoon into early evening. Storms bring brief IFR restriction and gusty wind while passing through the region. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms this afternoon and evening. * Low for ceiling 5000 ft or less in thunderstorms, moderate late tonight after cold front passage. && .PREV DISCUSSION... Issued at 255 AM EDT Wed Jun 26 2024 DISCUSSION... Strong upper level wave seen tracking through northern Minnesota early this morning, and is expected to move through Lower Michigan during the afternoon hours. Still some elevated surface dew pts around over southeast Michigan this morning, mid 60s to around 70 degrees. However, the tight tight 850-700 MB theta-e gradient along the southern Michigan border is sinking south, so our dew pts will be mixing down during the day. None-the-less, with the wave/shortwave trough approaching, some modest cold advection in the mid levels (heart of the cold pool moves through northern Lake Huron), at least high scattered showers appear in the offing as surface troughing persists over southeast Michigan through the day. MLcapes on the order of 1000+ J/kg will support isolated-low scattered coverage of thunderstorms as well, and if dew pts do not mix down during the day, MLcapes nearing 1500 J/kg would draw concern for severe storms as 0-6 KM bulk shear ramps up (exceeding 50 knots). The issue is the blossoming showers/convection over southern Wisconsin will likely be tracking through far southern areas during the late morning hours/early afternoon hours, complicating the forecast/instability as well. NAM soundings are a bit of an outlier late this afternoon, and will lean toward the more subdued/less cape solutions of RAP/HRRR/ARW/Canadian. Even so, the storms around noon will be strong and may approach marginal severe limits with the initial steep mid level lapse rates present, south of M-59. Upper level northwest confluent flow will allow sprawling high pressure to build into the Central Great Lakes tonight through tomorrow, and into the eastern Great Lakes Friday morning. Return flow around the high will ramp up through the day on Friday, with a strong and active warm front lifting through the Midwest. With the warm front arriving Friday night and the strong moisture advection (pw values of 2 inches feeding in), showers and thunderstorms are likely. Another amplified upper level trough/wave for summer standards swings through the Western Great Lakes on Saturday. Amount of destabilization in between the warm and cold front and position of the triple point will determine our severe chances, as a high degrees of 0-6 KM bulk shear arrives by early Saturday evening. MARINE... Upper level troughing has settled over the Great Lakes with surface high pressure over the upper Midwest gradually building into the central Great Lakes by late this evening. Before this occurs, a lingering weak frontal boundary over southern lower MI offers the potential for scattered showers and thunderstorms to develop during the daylight hours, mainly over waters south of Port Austin. Cooler northerly flow persists today and Thursday behind said front before flipping back to southerly Friday as the high center shifts east of the area. Winds during timeframe generally hold at or below 20kts. Unsettled weather arrives late Friday into the weekend as low pressure tracks into the upper Midwest. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....BT DISCUSSION...SF MARINE.......KDK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.