Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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734 FXUS63 KDTX 031946 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 346 PM EDT Fri May 3 2024 .KEY MESSAGES... - A broken line of showers will slowly track east across the area this evening, with a few thunderstorms possible. Severe weather is not anticipated. - High pressure fills in Saturday supporting mainly dry conditions ahead of the next weak cold front to bring showers and a few thunderstorms to SE MI early Sunday morning. - Seasonably warm temperatures expected through early next week with high temperatures in the low to mid 70s and lows in the 50s. && .DISCUSSION... Broken line of showers currently extends from roughly Saginaw to Coldwater, with no observed lightning activity at issuance. Instability has been the main limiting factor thus far, with MLCAPE holding aob 250 J/kg and observed temperatures generally in the mid to upper 60s. Pockets of sunshine ahead of the line may increase instability enough through the evening to support a few embedded thunderstorms, but for now storm tops have struggled to even reach the freezing level. Slow eastward progression of the line (15-20 mph) and waning instability after 00z with loss of diurnal heating may prevent the line from even getting to easternmost portions of the cwa. Post-frontal subsidence introduces a deep layer of static stability to the column overnight, most prominent near the Tri Cities and Thumb. In these locations, patchy fog is expected especially as onshore flow emerges from Lake Huron. Elsewhere, weaker inversion and poor decoupling signal suggest stratus or more localized fog development Saturday morning. Otherwise, a drier day is in store Saturday for SE MI. Upstream, a surface low lifts toward Lake Superior which effectively draws the theta-e axis back into lower Michigan by Saturday afternoon which boosts temperatures into the mid 70s. The boost to boundary layer conditions will be enough to build surface-based instability, but any convective initiation will depend on localized convergence or lake breezes. So at this point, just a stray shower or thunderstorm will be possible Saturday afternoon. Broader convective coverage is expected early Sunday morning as the surface low sweeps another cold front across the cwa. Persistent lack of mid-upper level jet support and modest elevated instability suggest showers and a few thunderstorms to be possible Sunday morning before clearing out by mid-day. Mid-level ridging then holds steady through middle of next week ahead of a strong Pacific disturbance which will be the next opportunity for widespread precipitation. High temperatures will remain comfortably in the 70s as an open Gulf and southwest flow keep conditions above average for early May standards. && .MARINE... A line of showers will continue to work east across the central Great Lakes this afternoon as a weak cold front pushes through. Isolated thunderstorms are possible, but severe storms are not expected. Light northeast wind will occur behind the front tonight with mainly dry conditions as a localized area of high pressure builds in. Will monitor observational trends over Lake Huron where conditions may be favorable for areas of dense marine fog to form overnight into Saturday morning. Winds then gradually organize out of the southeast on Saturday as the high departs east. Southerly winds up to 20 knots develop Saturday night ahead of the next cold front that will sweep through on Sunday. Scattered showers and storms will accompany the front with winds turning northwesterly behind it Sunday afternoon. High pressure then builds in to bring quiet marine conditions for the early work week. && .PREV DISCUSSION... Issued at 122 PM EDT Fri May 3 2024 AVIATION... A cold front on pace to advance from northwest to southeast across southeast Michigan mid afternoon through early evening. This front may ofer a modest focus for convective shower development during this time. While an isolated thunderstorm remains possible, the potential appears too limited to highlight given lack of greater instability. Cloud base generally at VFR within the pre-frontal environment, with evidence upstream for ceiling height to lower with time toward MVFR as low level moisture increases in the wake of the front this evening. Some degree of low cloud development and maintenance with an accompanying reduction in visibility expected overnight. Forecast will continue to highlight lower MVFR to IFR restrictions through the early-mid morning hours. For DTW/D21 Convection...Very low potential for a thunderstorm to develop between 21z and 01z. Limited instability precludes a mention in the forecast at this time. DTW THRESHOLD PROBABILITIES... * Low for thunderstorms 21z-01z * Low for ceiling 5000 ft or less through this evening. Medium tonight. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...MV MARINE.......TF AVIATION.....MR You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.