Algonac, Michigan Weather Forecast Discussion

626
FXUS63 KDTX 210943
AFDDTX
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
543 AM EDT Sun Sep 21 2025
.KEY MESSAGES...
- Scattered to numerous showers and thunderstorms today. Greater
coverage and intensity from mid afternoon through evening.
- There is a Marginal Risk of severe thunderstorms. Damaging wind is
the primary hazard.
- Showers continue Monday and Tuesday. Localized heavy rainfall will
be possible.
- Low potential for rainfall Wednesday through next Saturday as a
  ridge of high pressure is forecasted to build over the northern
  Great Lakes.
&&
.AVIATION...
Periodic isolated to scattered showers with some embedded
thunderstorms will be possible through the day today. There are a
couple of signals for higher end probability for shower development,
represented by PROB/TEMPO/FM groups, but overall shower and
thunderstorm development will be hit and miss across SE MI. The best
chance for any thunderstorm potential will be favored between 20Z to
04Z, but confidence in timing, coverage, and location of storm
potential remains low. Otherwise, these higher based shower and
storms are expected to keep ceiling heights elevated to aoa 5kft,
with some brief ceiling and visibility reductions possible with
thunderstorm activity. Any thunderstorm will be capable of producing
wind gusts in excess of 35 knots.
For DTW/D21 Convection... Increasing chances for isolated to
scattered showers in the late morning to early afternoon hours.
Then, low chances for embedded thunderstorms focused 20Z to 03Z
tonight.
DTW THRESHOLD PROBABILITIES...
* Low for ceilings at or below 5,000 feet today.
* Low for isolated thunderstorms to impact DTW today 20Z to 03Z.
&&
.PREV DISCUSSION...
Issued at 256 AM EDT Sun Sep 21 2025
DISCUSSION...
Moisture advection occurs over Southeast Michigan today as the
blocking ridge over the central Great Lakes finally breaks down.
Plan view progs do show low level jet axis already in place for a
good portion of today but precipitation chances will largely hold
off until after 20Z waiting for the main meridional thetae plume on
the 316-324Ke surfaces to release across/through the cwa. Hires runs
show a spread of outcomes today, with some guidance suggesting a
lean/very hit or miss potential. There does remain a signal that
suggests glaciated remnants in the 14-18z time window with a diurnal
re-inititation of showers and thunderstorms then after 20z. It is
this scenario the current Marginal designation in the Swody1 is
predicated on. Current 12hr forecasted PoPs are likely running a
little hot as coverage later today could be fairly sparse. Meager
midlevel lapse rates above what could be a relatively stable low
level environmental profile limits the MLCAPES to 750 J/kg or less.
An inverted V structure to the sounding with 0-6km bulk shear of 30-
35 knots may support a strong to severe thunderstorm today. A wind
gust in vicinity of thunderstorm activity of 40-60mph may be
possible.
A pseudo cold frontal feature is forecasted to organize and be
forced southward through the forecast area tonight. The cold front
will result from the combination of anticyclonic vorticity advection
and dynamic subsidence from confluence aloft. The boundary is
expected to clear Southeast Michigan to the south then stall out in
vicinity of Downriver and western Lake Erie basin for a good portion
of Monday afternoon. Look and feel of the plan view thetae progs
suggest a favorable corridor of frontogenesis and system relative
isentropic ascent across the area. Uncertainty in coverage, but
models do suggest the greatest potential for precipitation and qpf
potential will fall late Monday. Current forecast has categorical
PoPs. Difficult to discuss QPF amounts for individual periods, but
the interquartile range of ensemble data suggests Sunday and Monday
QPF totals of .75 to 1.50 inch will be possible. The real wildcard
is what will occur on Tuesday and some model solutions suggest an
MCV may emerge out of Central United States thunderstorm activity
and track towards the state.
Model trends continue to support a ridge of surface high pressure
building over the northern Great Lakes from Wednesday through next
Saturday. Gradient setup supports a northerly wind direction with
comfortable daytime temperatures near 70. The current forecast has
an extended run of lower PoPs that will likely need to be refined
(lowered).
MARINE...
High pressure over New England gradually departs into the Atlantic,
allowing broad low pressure over the upper Midwest to exert
increasing influence over the central Great Lakes today. Benign
weather early gives way to increasing probabilities for showers and
thunderstorms this afternoon and evening as the low ushers in a warm
front. Isolated stronger storms will be capable of producing
localized wind gusts in excess of 34 knots and waterspouts. Wind
prevails out of the southeast at around 10 kt today, then shifts to
southwest Monday while remaining around 10 kt. An unsettled
showery/stormy pattern continues through Monday into Tuesday as
multiple disturbances pass over the region along with a slow moving
frontal boundary.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
AVIATION.....AM
DISCUSSION...CB
MARINE.......TF
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at www.weather.gov/detroit.

NWS dtx Office Area Forecast Discussion