468 FXUS63 KDTX 230011 CCA AFDDTXArea Forecast Discussion...CORRECTED National Weather Service Detroit/Pontiac MI 811 PM EDT Mon Sep 22 2025
.KEY MESSAGES...
- Scattered showers and thunderstorms will be possible through the middle of the week. Localized heavy rainfall may be possible.
- Temperatures in the 70s throughout the week which will generally be at to slightly above normal.
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.AVIATION...
VFR conditions have emerged this evening with one single lingering observations of a BKN MVFR ceiling at PTK to start this TAF period. Radar trends lean towards a lack of rain showers across southeast Michigan at least for the next few hours. The high degree of low level moisture still may allow for isolated showers to pop up this evening, mainly towards MBS. The combination of light winds and the higher surface moisture will then bring favorable conditions for fog to develop during the early morning hours with MVFR to IFR VSBYs in play. Typical lifting of any foggy areas during the first few hours of sunrise will be followed by renewed chances for showers and isolated thunderstorms during the afternoon and early evening. Coverage of activity may be more isolated, so will be highlighted by PROB30 groups. Winds will remain light and out of the southwest tomorrow with ceilings with a mix of MVFR and low VFR ceilings.
For DTW/D21 Convection...Low potential for thunderstorms tomorrow afternoon. Most favorably time frame is between 17Z to 23Z. Confidence is too low to mention in TAFs at this time.
DTW THRESHOLD PROBABILITIES...
* Low for ceilings at or below 5,000 feet, becoming medium late tonight.
* Low for cigs/vsby to fall to 200ft and/or 1/2sm late tonight.
* Low for thunderstorms to impact DTW tomorrow afternoon.
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.PREV DISCUSSION... Issued at 400 PM EDT Mon Sep 22 2025
DISCUSSION...
Southeast Michigan holding position late this afternoon within the southern expanse of broad mid level troughing emanating from a closed low migrating across lake Superior. Underlying low level environment remains characterized as moist and weakly unstable, as daytime heating works to lift afternoon temps into the 70s. A more noteworthy gradient in instability emerging as early day convective activity across areas generally south of I-69 effectively limits the degree of destabilization across the corridor, while points north push toward 700-1000 j/kg of mlcape. While the overall forcing field remains rather nebulous, a more focused corridor of ascent emerging across central lower mi as shortwave filaments pivot through the mid level cyclonic periphery. This ascent evident with ongoing activity lifting across west-central lower mi. This will offer the highest probability for additional convective development for areas mainly north of I-69 going forward into the evening hours. Precip chances will be tapered lower accordingly with southward extent. Sufficient deep layer shear to offer modest organization potential, but with paltry mid level lapse rates capping prospective convective depth. Gusty winds and brief heavy downpours with any activity through early tonight. Model signal exists for some degree of low stratus and/or fog formation late tonight owing the high near surface moisture content. Lower confidence yet in defining scale of any development, as lingering higher based cloud and sufficient low level gradient may prove disruptive. Introductory mention of patchy fog for late tonight sufficient at this stage.
Little variation in overall conditions Tuesday. A moist low level profile will again contribute to weak instability as daytime heating lifts temperatures into the 70s and maintains a steeper low level lapse rate environment. MLcape peaking at 700-1000 j/kg. Additional pockets of dcva projected to work through the existing mid level trough along the nose of an upper level jet. This occurs as a weak frontal boundary sags southward into the region. Overall environment supportive of a chaotic coverage of showers and thunderstorms with a peak in coverage mid afternoon into the evening hours. Gusty winds and locally heavy downpours with any stronger cores.
Strong height falls lifting out of the plains will undercut the great lakes upper low, establishing a deeper, positively upper trough for the late week period. Some differences across the model spectrum yet in terms of handling this interaction, but general expectation exists that sufficient separation of height falls will hold the associated surface low and attendant deeper moisture plume over the Ohio valley as the system pulls east. Local area will remain susceptible to intervals of showers and thunderstorms tied closely to daytime heating both Wednesday and Thursday with continued moist cyclonic flow as the upper low eases through. The unsettled conditions with prevailing low level easterly flow will favor highs near average or slightly below. Drier conditions return Friday with a window of greater warm air advection lifting temperatures back above average into the first half of next week.
MARINE...
An upper level trough is draped over the Great Lakes and will slowly drop southeast through mid week. Additionally, a warm front up across the Straits will drop southward through the region on Tuesday. This will lead to an extended period of unsettled weather with multiple rounds of showers with occasional embedded thunderstorms. Pressure gradient is weak and winds aloft are also weak so chances of any stronger winds or gusts with storms are lower. Winds will flip from southerly today to northeasterly Tuesday to which they`ll remain through midweek.
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.DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. &&
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AVIATION.....AA DISCUSSION...MR MARINE.......DRK
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NWS DTX Office Area Forecast Discussion