Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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947 FXUS63 KDTX 260655 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 255 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. && .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. && .PREV DISCUSSION... Issued at 1147 PM EDT Tue Jun 25 2024 AVIATION... Some pockets of lower stratus will exist across the Detroit corridor early this morning as low level moisture quality improvies, but with observational evidence suggesting coverage remains at scatterd. A brief broken coverage remains possible through this corridor, featuring a lower VFR/marginal MVFR ceiling. This moisture may offer a window for shallow fog formation during the early morning hours, although confidence in occurrence remains quite low owing to substantial high cloud and existing low level southwest gradient. A moist and weakly unstable environment brings potential for shower and thunderstorm development during the daylight period Wednesday. Greater potential with southward extent, highlighted by a main window from PTK southward for some convective showers and a lower probability mention of tsra. Prevailing southwest winds lasting throughout the day, shifting to northwest a frontal boundary sags through the region late afternoon into the evening. For DTW/D21 Convection...Low probability for thunderstorms will exist from late morning into the afternoon on Wednesday. DTW THRESHOLD PROBABILITIES... * Low for ceilings aob 5kft overnight and Wednesday. * Low for thunderstorms Wednesday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...SF MARINE.......KDK AVIATION.....MR You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.