Davisburg, Michigan Weather Forecast Discussion

594
FXUS63 KDTX 211953
AFDDTX
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
353 PM EDT Sun Sep 21 2025
.KEY MESSAGES...
- Scattered showers and thunderstorms this evening become more
  numerous late tonight and Monday morning.
- There is a Marginal Risk of an isolated severe storm tonight along
  and south of the I-96/696 corridor. Damaging wind is the primary
  hazard.
- Showers continue Monday and Tuesday with localized heavy rainfall
  possible.
- Probability for showers is lower during the late week period
  depending on the eventual location of low pressure stalled in the
  Ohio valley.
&&
.DISCUSSION...
Assessment of timing, coverage, and intensity of additional
thunderstorm activity in SE Mi is the forecast focus for tonight.
Early day trends extend into this afternoon with heavy influence
from the broken band of showers just now exiting into Ontario. The
band exhibited some mesoscale circulation in satellite and radar
imagery within the mid level trough as it passed across Lower Mi and
has left behind a substantially rain-cooled boundary layer. The
mesoscale structure points to a greater component of wake subsidence
responsible for the cloud decrease observed farther west into SW
Lower Mi and WI/IL, suggesting further delay in new storm initiation
while greater surface heating helps instability recover. Hourly
mesoanalysis measures a considerable instability gradient serving to
reorient the front that has been stalled south of the IN/OH border
to warm front across southern Lower Mi. Surface based CAPE projected
up to near 2000 J/kg in the SW Lower Mi warm sector is a good
candidate area for expansion of WI/IL convection as mesoscale
subsidence transitions to a weakly supportive influence from the
background mid level trough. Loosely organized multicell convective
mode is then possible while instability builds from the Ohio border
up to near the I-96/696 corridor roughly outlined by the updated
Marginal Risk area. Eventual northward and eastward reach will be
limited by less recovery of instability as surface based CAPE wanes
after sunset.
The forecast keeps rain probability elevated late tonight into
Monday morning as forcing transitions from surface based convection
to a weak low level jet scenario. This evolves as the 500 mb trough
remains over northern Ontario and the upper Midwest allowing the
primary surface front to shift toward the Straits into the northern
Plains. A diffuse warm sector environment across southern Lower Mi
then supports scattered showers and an isolated storm off surface
based instability during the afternoon into Monday evening.
The northern Great Lakes to central Plains cold front settles
southward with yet another round of scattered showers and storms for
SE Mi later Monday night and Tuesday until the front reaches
northern IN/OH by evening. Predictability drops off considerably
after that as the southern stream long wave mid level flow
transitions back to a more fully blocked character. The range of
deterministic model solutions is wide around the size and location
of the 500 mb closed low and therefore the position of the surface
low and northward extent of showers into Lower Mi during the late
week period.
&&
.MARINE...
An upper level trough moves into the Great Lakes today into Monday
before stalling overhead Tuesday. This system sends a disorganized
frontal boundary across the area, first as a warm front tonight and
then again as a cold front on Tuesday. This favors an unsettled
pattern with showers and embedded thunderstorms through the early
week. The pressure gradient will remain relatively weak with
prevailing southeast wind today veering southwest on Monday before
shifting to northeast on Tuesday. Wind speed will remain on the
order of 10 kt through this period, though any isolated stronger
storms that develop this afternoon and evening would be capable of
localized wind gusts in excess of 34 knots and waterspouts.
Probability remains low for stronger storms but is greatest over
western Lake Erie. A low pressure system emerging out of the central
Mississippi Valley will be monitored mid week for additional precip
chances and potential for an uptick in east/northeast wind.
&&
.PREV DISCUSSION...
Issued at 156 PM EDT Sun Sep 21 2025
AVIATION...
A north to south oriented line of showers will push east of the taf
sites mostly by 19Z today with a lull in showers after that for a
few hours. A warm front located just south of the MI border will
lift through southern MI this evening into tonight, keeping chances
for showers across the area through morning. Timing any periods of
showers will be difficult as there is little agreement between the
models in this moist, weakly forced environment. We`ll continue to
highlight periods with tempo/prob30 as confidence dictates. So far
there has been no thunder over SE MI, and though there is a chance
this evening if we can build some instability behind this line of
showers, confidence/coverage is too low to include in a taf at the
moment. CIGs will largely remain VFR outside of any brief lowering
with showers. There could be MVFR CIGS developing in the morning
south of the front, but soundings still want to stay above 5kft.
For DTW/D21 Convection... This round of showers should end between 19-
20Z with a lull expected later this evening. Chances for showers
continue through morning but we`ll highlight early Monday morning as
the next best chance with more isolated coverage possible this
evening. Low chance for thunder to impact the terminal this evening
but best chance would be before 00Z.
DTW THRESHOLD PROBABILITIES...
* Low for ceilings at or below 5,000 feet today.
* Low for thunderstorms to impact DTW today with the best chance
  would be before 00Z.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
DISCUSSION...BT
MARINE.......TF
AVIATION.....DRK
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at www.weather.gov/detroit.

NWS DTX Office Area Forecast Discussion