547 FXUS63 KDTX 170713 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 313 AM EDT Thu Apr 17 2025 .KEY MESSAGES... - Showers and possible thunderstorms developing late tonight, particularly north of I-69. - Warm and windy on Friday with high temperatures well into the 70s to near 80 degrees. Southerly wind gusts of 30-40 mph expected in the afternoon. - There is a slight risk of severe thunderstorms Friday evening into early Friday night. && .DISCUSSION... A cold and frosty morning to start the day, as temperatures rise out of the mid 20s to lower 30s. Water vapor imagery shows a potent upper level wave dropping south through the Pacific Northwest, which will drop into the Four Corners region by Friday evening. This feature will help direct subtropical moisture/energy into the western Great Lakes by Friday morning. Thus, still looking at an active warm front, but the 850-700 MB jet core (60+ knots) is forecasted to track through northern Lower Michigan (6-10z), thus confidence in showers and even possible thunderstorms (as negative showalter indices arrive) does drop off as one heads southeast. With that said, still think majority of southeast Michigan will see showers Thursday night after looking at various hi-res solutions, and knowing the models typically struggle with the elevated high based activity/warm advection wing. Locations north of M-46 overwhelmingly stand the best chance to exceed rainfall of a quarter of an inch through 15z Friday. 00z HRRR is even developing an aggressive MCV moving through, which would bring a small hail threat with very steep mid level lapse rates. Tough to latch onto this solution fully just yet. Surface warm front should make it to Saginaw Bay during the day, placing the bulk of southeast Michigan in the warm sector. The question is how clean will the warm sector be, as the NAM is exceptional moist in the low levels, keeping low clouds in locked in, with even some drizzle/very light rain possible. Preference is with a drier, warmer, and subsequently windier solution with the increased mixed depths, as suggested by regional gem. Our local probabilistic guidance suggests wind gusts of 35-40 MPH as temperatures have potential to reach 80 degrees with 850 MB temps reaching at or above 13 C. Extreme capping, mid level warmth and dry air indicated after the early morning activity exits, thus not expecting any thunderstorm activity in the afternoon, as MUcapes reach 750-1500 J/kg. Cooling mid levels and large scale ascent attempts to spread in during the evening, but low levels will be stabilizing, with capes cut in half by midnight. SPC Day 2 outlook continues to advertise a slight risk of severe thunderstorms. The steep mid level lapse rates and wind shear certainly needs to be respected, and our severe chances (hail/wind/very low risk of tornado) hinge on the timing of the activity/cold front moving in earlier in the evening. However, preference is toward the muted solutions such as the 00Z Euro/NAM, suggesting the front will be arriving just a bit too late to support much in the way of severe thunderstorms, as the cap is just too strong and takes too long to be eroded. The front is actually losing its forward speed Friday night, and the boundary may hang around the southern Michigan border Saturday morning, as an upper level shortwave tracks northeast through the Ohio Valley. If this shortwave is stronger and a surface reflection develops, could see rain showers impact southern areas on Saturday (see Canadian solution), but confidence is not high in this scenario as high pressure builds east through the northern Great Lakes. This high will give way to another strong low pressure system tracking through the western Great Lakes Sunday night, bringing another round of showers and possible thunderstorms to end the weekend into Monday. Once again, the bulk of the activity and heavy rain looks to reside northwest of the CWA. && .MARINE... Quiet marine conditions expected today under light southeast flow. Gradient wind increases throughout the day as low pressure organizes over the Plains. Elevated portions of the warm front move toward the Great Lakes early Friday morning, triggering elevated showers and thunderstorms along with an uptick in winds and wave action that may require Small Craft Advisories. Once morning convection subsides, warm conditions develop across the Great Lakes ahead of the system cold front which will slowly track across the area late Friday night- Saturday morning. This front will be the focus for additional thunderstorm activity, in which some storms could become strong to severe depending on how unstable the atmosphere gets. The front slowly settles into the Ohio Valley, but may trigger additional rounds of precipitation through the weekend. && .PREV DISCUSSION... Issued at 1203 AM EDT Thu Apr 17 2025 AVIATION... VFR conditions will prevail through the TAF period with southeast Michigan currently under the influence high pressure and dry air. Light and variable winds expected through the early morning hours under clear skies. High clouds increase throughout the day tomorrow ahead of the next low pressure system as winds become southerly. There will be an increasing chance for rain showers near the end or shortly after the end of this TAF period. Highest chances focused toward FNT and MBS. DTW THRESHOLD PROBABILITIES... * None && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...SF MARINE.......MV AVIATION.....AA You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.