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Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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173 FXUS63 KDTX 071636 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1236 PM EDT Sun Jul 7 2024 .KEY MESSAGES... - The holiday weekend closes out with dry weather today under partly sunny skies. - Warming up into Monday with highs in the mid to upper 80s. Shower and thunderstorm chances return Monday and Tuesday. - Remnants of Beryl may begin to impact parts of the area by Tuesday night and Wednesday. && .AVIATION... Remnant low level moisture along/east of a KDET to KMBS line resulted in a sct-bkn MVFR based cu field late this morning. Ongoing boundary layer growth through diurnal mixing will support an increase in the cloud bases to 4-6k feet during the course of the afternoon/early evening. Otherwise, high pressure anchored across the eastern Great Lakes will maintain light winds and will inhibit a late day convective response. For DTW/D21 Convection...Thunderstorms are expected across the airspace today and tonight. DTW THRESHOLD PROBABILITIES... * None && .PREV DISCUSSION... Issued at 310 AM EDT Sun Jul 7 2024 DISCUSSION... Upper level ridging will translate in the region today and provide mostly sunny conditions with temperatures warming back into the low 80s in most locations (upper 70s over the Thumb). The upper ridge axis will shift a bit east into Monday with strengthening south to southwest flow developing between this feature and an encroaching weak frontal boundary to the northwest. Temperatures will continue to warm within this regime with middle 80s common by afternoon (and upper 80s possible metro Detroit south). The chance for scattered showers and thunderstorms will increase into the afternoon and evening period as the aforementioned frontal boundary shifts into the forecast area late Monday. At this time, it appears convection will most likely be most prevalent over the north to northwest one quarter to one half of the forecast area where the best frontal forcing will reside along northwest edge of remaining upper level ridge. This forcing will act on an increasingly unstable airmass as surface dew points edge into the upper 60s to around 70. This should promote SBCAPES nearing 1500 J/kg locally. Stronger mid level flow will also translate into the area and increase deep layer shear from about 20 knots midday to 30-40 knots into the evening. So, the combination of these two modestly supportive parameters may lead to a few stronger storms. This frontal boundary will settle into the remainder of the forecast area Monday night into Tuesday, but stall over/near the area as the positive tilt upper level trough driving this front southeast minors out as it crosses the area Tuesday. This will maintain rain chances into Monday night and to some degree into Tuesday (although model differences are substantial in terms of active convection along/near this front by that time). The largest forecast challenge that appears to be emerging is how the remnants of Beryl will initially interact with this stationary frontal boundary by the middle of the week (Tuesday night into early Wednesday) as it is steered around the northwest periphery of the western extension of the Bermuda high centered over the Atlantic and then just where the remnant low ends up tracking as it rounds the top of this ridge over the southern Great Lakes/northern Ohio Valley later Wednesday into Wednesday night. This general idea having Beryl impact the area was basically "new" to the model suite at the 00z cycle Friday night and the 00z suite for Saturday remains notably divergent in the exact progression of events (although all models have the system over/near the area now). This will be a significant rain producer for a rather wide swath of the southern/eastern Great Lakes and/or northern Ohio Valley. While details remain elusive, it appears that increasing the chance of rainfall in this late Tuesday night to Wednesday night period seems prudent. MARINE... A ridge of high pressure centered over the Ohio Valley maintains dry conditions with light winds and low waves the rest of the weekend. Southerly wind of around 10 knots develops on Monday ahead of the next frontal system moving in from the Midwest. Scattered showers and storms arrive over northern Lake Huron Monday morning before expanding south and east into the evening. Additional showers and storms will be possible into Tuesday as the system slowly continues tracking through. The mid-week carries a considerable amount of uncertainty but the potential exists for a period of heavy rain and strong winds if the remnants of Tropical System Beryl track in the vicinity. HYDROLOGY... The remnants of Beryl may very well begin to interact with a stalled frontal boundary along the southern portion of the forecast area by Tuesday night with the remnant low then tracking into the vicinity Wednesday into Wednesday night. At this time, details on the track of this system are difficult to determine. Suffice it to say that an increased risk of heavy rainfall will exist as the system encroaches on the area. If impacted directly, rainfall will most likely reach or exceed 2 inches in some areas. Follow upcoming forecasts as the forecast track into this general part of the country is fine tuned. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....SC DISCUSSION...DG MARINE.......TF HYDROLOGY....DG You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.