


Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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035 FXUS63 KDTX 080743 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 343 AM EDT Tue Jul 8 2025 .KEY MESSAGES... - Dry and seasonable conditions today. - More humid conditions return tonight and Wednesday, bringing an increasing potential for showers and thunderstorms. Severe weather is not anticipated with this activity, but locally heavy rainfall and gusty winds are possible. - Lesser potential for showers and thunderstorms Thursday as drier air works back into the region. Dry and warmer conditions then expected Friday. && .DISCUSSION... Lower amplitude westerly flow to govern conditions through this afternoon. General mid level subsidence atop pervasive surface high pressure will maintain a high degree of deep layer stability and corresponding benign conditions. Limited moisture quality throughout the column ensures high insolation potential, lending a boost to an already moderating thermal profile off the notably colder readings from yesterday. Afternoon readings back to around early July norms - highs low to mid 80s. Minor shortwave energy lifting through the mean flow will offer some reduction in mid level heights beginning tonight. This process will draw a weak warm front through the region, while establishing a period of greater moisture advection overnight. Signal remains across the model spectrum for associated ascent to prove sufficient in generating some widely scattered nocturnal showers and thunderstorms across the lower peninsula. A more focused, higher probability of precipitation could materialize by late tonight/Wed morning should a greater corridor of dcva emerge tied to a passing pv feature. Broad lower amplitude mid level troughing established for the Wednesday period, as the main height fall center/closed low pivots across Ontario. Trailing surface trough arrives for the daylight period and offers a primary focus for additional convective development. Early day cloud/shower potential could dampen the pace of diurnal destabilization for at least a portion of the area, while also potentially establishing a greater differential heating boundary to provide an additional focus. In general, a modest level of instability projected. This in combination with a lack of a greater wind field suggests simply garden variety activity. The elevated moisture content again brings potential for any water loaded updrafts to generate locally higher rainfall rates and gusty winds during the afternoon and evening. Weakly cyclonic mid level flow will persist into Thursday. A potential transition day as drier air upstream attempts to arrive during the daylight period as northwest flow emerges upon exit of low level troughing. Mixed signal yet regarding pace of this process, thus leaving the door open for east/southeast sections to maintain an adequately moist and weakly unstable environment to support a lower end chance of convective development. Further revision of rain chances likely this period. Greater stability as low to mid level ridging arrives lends to higher confidence for dry conditions Friday. Corresponding increase in mean thicknesses would also support a modest warming trend to finish the week. Conditions appear more unsettled for at least a portion of the weekend period, as a more dynamic wave projects to lift across the great lakes. Scattered to numerous showers and thunderstorms already highlighted by latest NBM output for Saturday. && .MARINE... Light and variable winds to start as the surface pressure field trends more diffuse. Favorable marine conditions are expected until the overnight hours as the next low pressure system drags a cold front across Lower Michigan. Winds then organize out of the ESE, ahead of the surface low, with a tightening gradient. Expect a period of showers and thunderstorms within a pre-frontal warm sector for the southern waterways and activity along the cold front further north, moreso for Lake Huron. Ambient dynamics are rather weak which should keep prevailing conditions below Small Craft Advisory criteria, but locally higher winds/waves are possible with some stronger storms. Additional isolated to scattered convection is possible Thursday, particularly south of Lake Huron. && .HYDROLOGY... Scattered to numerous showers and thunderstorms are forecast Wednesday. Storms will be relatively disorganized, but with humid conditions and slow storm movement, storms will be capable of producing torrential downpours. Localized areas may receive over 1 inch per hour, which may lead to flooding of urban areas, small streams, and otherwise poorly drained areas. The main threat for flooding will be between 1pm and 8pm. && .PREV DISCUSSION... Issued at 1153 PM EDT Mon Jul 7 2025 AVIATION... VFR consists of thin cirrus streamers or clear sky as high pressure builds in from the Midwest late tonight. The inbound air mass is cooler and less humid, however radiational cooling is potentially in reach of surface Td stalling the mid to upper 50s by sunrise. This makes a few hours of light/shallow MVFR fog possible toward sunrise that quickly dissipates in early July morning sun. Clear sky or mixed mid and high clouds during the morning transition to cumulus development in the afternoon. These clouds result from warmer and more humid air returning on SW wind as high pressure slides eastward through Tuesday evening. A stray shower becomes possible later in the evening and mainly north of the DTW corridor. For DTW/D21 Convection... Thunderstorms are not forecast tonight and Tuesday. THRESHOLD PROBABILITIES... * None. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...MR MARINE.......KGK HYDROLOGY....MR AVIATION.....BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.