


Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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067 FXUS63 KDTX 281934 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 334 PM EDT Sat Jun 28 2025 .KEY MESSAGES... - Mostly sunny with seasonable high temperatures in the 80s today. - Warm and muggy conditions return Sunday and Monday with highs on Sunday near 90 degrees. - Showers and thunderstorms likely on Monday, mainly during the afternoon and evening. There is a low probability for an isolated severe storm. && .DISCUSSION... A progressive, low amplitude upper air pattern dictates this weekend`s weather. A shortwave ridge axis within a relative weakness in the jet stream passes overhead tonight into Sunday to maintain dry and stable conditions. Advection of lower boundary layer dew points into the 50s and lower 60s behind this morning`s cold front has brought some relief from the recent muggy conditions with dry air throughout the mid and upper troposphere offering mostly sunny skies into this evening. This leads into mostly clear skies through tonight with lows settling into the 60s. Burgeoning southwest flow ensues by Sunday afternoon as the ridge axis passes east with a warm front bringing in the next round of heat and humidity. Temperatures upstream over the Midwest support highs around 90 with dew points creeping back toward the upper 60s to around 70 degrees by late in the day. This will bring increasing instability through the late afternoon. However, capping and convective inhibition is also expected to increase as an EML advects in from the northern plains - sending 850mb temps to near 19 C. Also of note is the lack of support for ascent with system relative flow trajectories exhibiting lingering anticyclone influence beneath the ridge. A convective shortwave is progged to track across northern MI during the evening which will be a feature to monitor as several hi- res runs continue to show some signal for isolated, disorganized convection in the vicinity of the Tri-Cities and Thumb. Effective bulk wind difference is progged to be below 20 knots supporting short lifespan and low severe risk from any convection. The hot and muggy conditions persist into Monday amidst continued southwest flow ahead of an amplifying mid-level trough dropping in from the upper Midwest. Minimal capping is shown in model soundings with increasing support for ascent via DCVA as a shortwave tracks in ahead of the trough. Surface moisture convergence progs show ample convergence for storm initiation along a pre-frontal trough during the late afternoon/evening. As a result, numerous showers and scattered thunderstorms will become likely. Dew points hanging in the upper 60s to lower 70s with modest mid-level lapse rates around 6 C/km will support MLCAPE on the order of 1000 J/kg which can lead to some strong updrafts. Low-level shear is weak but southwest flow at 500mb will trend up to around 30 kt to support potential for some updraft organization. PWAT around 1.75 inches suggests any mature convection will be capable of producing heavy downpours with precip- loaded downdrafts bringing an isolated damaging wind threat. Available machine learning guidance shows increased severe wind gust probabilities for parts of the Lower Peninsula on Monday and this will be something to monitor. The cold front passes through the area Monday night with showers and storms likely to taper off during the late evening. The inbound air mass has Canadian continental origins with 850mb temp around 14 C. A cutoff low over coastal CA induces downstream ridging over the Rockies which maintains relative troughing over the Great Lakes to hold a similar air mass in place through the week. Temps and humidity should hold near typical early July values. An upper low arrives within the NW flow on Thursday to bring the next chance for unsettled weather. Ensemble guidance then leans toward producing a mid-level ridge over the SE CONUS by next weekend, signaling a return of above normal temps to the Great Lakes. && .MARINE... A ridge of high pressure will provide light winds and low waves over the Central Great Lakes through tomorrow morning. Light southerly flow under 20 knots develops tomorrow afternoon ahead of the next low pressure system, which enters the northern Great Lakes Sunday night into Monday driving a stronger cold front through the region. This cold front will provide additional storms Monday and a stronger post-frontal wind field Tuesday, around 20 knots && .PREV DISCUSSION... Issued at 158 PM EDT Sat Jun 28 2025 AVIATION... Cumulus field has proven rather formidable early this afternoon, especially for the northern sites (MBS/FNT) with pockets of MVFR ceilings still lingering amidst surface high pressure encompassing Lower Michigan. Favorable diurnal heating should continue to gradually lift ceilings above 3 kft AGL within the next hour or two, ushering in an extended period of VFR conditions. Breezy, with occasional WNW gusts around 20 knots until speeds drop-off this evening and overnight. Remaining low cloud also dissipates tonight with just a bit of residual high cirrus as winds trend toward calm. Can`t rule out a bit of fog, but visibilities should generally hold VFR, above 5 SM. Any fog that develops will burn off quickly Sunday morning while limited available column moisture prevents meaningful low cloud fraction through the end of the TAF cycle. Surface flow backs south-southwesterly Sunday with speeds below 10 knots. For DTW/D21 Convection...No thunderstorms expected through the TAF period. THRESHOLD PROBABILITIES... * Low in ceiling at or below 5000 ft beyond 19Z this afternoon. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...TF MARINE.......SF AVIATION.....KGK You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.