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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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123 FXUS63 KDTX 171859 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 259 PM EDT Wed Jul 17 2024 .KEY MESSAGES... * An upper level disturbance will cross through Lower Michigan this afternoon and produce scattered showers and thunderstorms into early this evening. * High pressure brings cooler, drier, and less humid conditions to the region through the end of the workweek. * Temperatures moderate over the weekend as high pressure departs, followed by an approaching boundary Sunday which offers low-end precipitation chances. && .DISCUSSION... Passing mid level upper trough axis and associated mid level cold pool will support isolated to scattered convection this afternoon into early this evening as it sweeps east through the forecast area. The most robust activity will impact areas just north of the region, but some degree of a southern expansion is expected along the trough this afternoon. With H5 temperatures to -15C or below (helping to generate SBCAPES of 500-1000 J/kg during peak afternoon heating), a few stronger updrafts will likely produce isolated small hail. This activity will be most pronounced in the 2-5 pm time frame with any lingering activity early this evening dissipating and it progresses east out of lower MI. Cool conditions for mid July can be expected as this upper trough digs through the area with minimum temperatures in the lower/mid 50s late tonight and again Thursday night. Meanwhile, high temperatures on Thursday will hold in the low/mid 70s. The Canadian high pressure responsible for the cooler conditions will moderate into the weekend with temperatures building back into the lower 80s in most cases (but with relatively low humidity levels). Even as the high pressure does weaken in time, generally dry weather will persist into Sunday with perhaps an isolated late day shower possible by that time. Similar temperatures in the upper 70s to lower 80s will persist into early next week as main upper level ridging remains positioned well off to the west mainly from the high plains into the Rocky Mountains on to the west coast. Some minor shower chances look to re-establish in this later portion of the forecast. That said, confidence is very low in details as no particularly impressive synoptic scale systems are slated into the area. At most, it appears a weak mid level wave that cuts off over the central plains/midwest this weekend may be pulled east into the area in advance of another decent shortwave dropping southeast through eastern Canada into the Great Lakes and northeast CONUS. && .MARINE... Once scattered showers and isolated thunderstorms clear this afternoon, cooler and drier air settles into the Central Great Lakes through tomorrow, as a large Canadian high pressure buids over the region. This expansive high will provide dry and benign marine conditions right through the Weekend and into early next week. && .PREV DISCUSSION... Issued at 1237 PM EDT Wed Jul 17 2024 AVIATION... Secondary cold front tied to an upper trough dropping out of Canada works across the region this afternoon-evening generating scattered showers. While some thunder is possible, and has been observed over late morning activity over northern lower MI, confidence in occurrence over a terminal is not high enough to include mention in running TAFs. Upped the Detroit terminals to Tempos given radar/satellite trends over central MI showing showers already developing around Lansing. Front clears the area by roughly 00Z this evening ushering in a cooler, drier airmass. MVFR stratus currently dropping south from northern Great Lakes will work into SE MI overnight however latest model trends suggesst that the will be just enough dry air to result in SCT coverage over BKN. For DTW/D21 Convection...Scattered showers develop this afternoon as a secondary cold front approaches. Isolated thunder is likely within this activity though coverage is limited in such that confidence isn`t high enough to include mention in TAF. DTW THRESHOLD PROBABILITIES... * Low in thunderstorms this afternoon. * Medium in ceilings aob 5000ft tonight. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...DG MARINE.......sf AVIATION.....KDK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.