Genoa Township, Michigan Weather Forecast Discussion

541
FXUS63 KDTX 181930 CCA
AFDDTX
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
307 PM EDT Thu Sep 18 2025
.KEY MESSAGES...
- A weak cold front brings scattered showers and thunderstorms this
  afternoon-evening, focused north of I-69.
- A little cooler Friday and Saturday, then a chance for showers
  Saturday night.
- Warmer Sunday with increasing storm chances, then cooler and wetter
  next week.
&&
.DISCUSSION...
A pattern shift gets underway today after a prolonged period of dry
weather; the last day with measurable rainfall at one of the three
DTX climate sites dates back to September 5th (at MBS). Scattered
afternoon convection has initiated over central Lower Michigan and
is tracking towards the Tri-Cities and Thumb regions. This activity
precedes a cold front attempting to drop south across the Lower
Peninsula and Lake Huron. Moisture progs aren`t very impressive
given ambient dryness and weak pre-frontal ThetaE convergence,
therefore deep-layer saturation and instability will be lacking.
Nonetheless, still expect some convective persistence along with
additional clusters of showers and thunderstorms through the evening
hours, predominantly north of I-69 where FGEN and dewpoints are more
supportive of rainfall. The threat for severe weather is low given
MLCAPEs below 250 J/kg and bulk shear of 20 knots or less, but the
dry boundary-layer could lead to a few stronger gusts (less than 40
mph). Activity should diminish by late evening as the storms
collapse within an area of higher CIN, south of M-59.
More seasonable weather expected for most locations on Friday as the
front eventually stalls near the MI/OH/IN border. 850 mb
temperatures drop into the low teens (Celsius) capping highs in the
upper 70s for most areas. An upper-level ridge axis, wedged between
a longwave trough over Quebec and a closed upper low over The Plains
promotes column stability across Southeast Michigan Friday,
providing mainly dry conditions. Surface high pressure builds
southeastward into central Ontario offering northeasterly gradient
flow that delivers cooler readings within the Huron lakeshore.
Morning clouds eventually give way to increasing sun by the
afternoon hours.
The cut-off upper low pivots into the Upper Midwest on Saturday,
interfacing with the northern stream jet. This closed low aloft then
phases with a shortwave trough digging across the High Plains.
Glancing energy off the eastern fringe slides in atop the stalled
frontal boundary retreating northeastward as a warm front. This
combined forcing brings renewed shower/storm chances late Saturday
into Sunday. The perturbed mid-level flow and stronger LLJ winds
support periods of thundershowers Sunday PM after an uptick in
dewpoints (lower 60s) settle in. A rather sharp drop in geopotential
heights arrives late Sunday into Monday as the vicinity upper low
ejects into eastern Canada. This sets up a cooling trend for next
week with additional opportunities for rain.
&&
.MARINE...
A cold front drops southward across the region today, reaching the
southern basin of Lake Huron by early afternoon and western Lake
Erie this evening. This will be marked by an increase in north to
northwest wind to around 10 to 15 kt. Funneling effects on Saginaw
Bay will result in a localized northeast wind direction and locally
higher gusts of around 20 kt. There will also be chances for
scattered storms late this afternoon into the evening, mainly across
the Saginaw Bay region. Strong high pressure then builds in across
northern Ontario which produces northeast flow across the region
Friday with sustained speed of 15 to 20 kt and gusts near 25 kt
across Saginaw Bay and southern Lake Huron. Wind veers to east and
southeast by Saturday, with the higher magnitude of wind shifting
toward the northern Lake Huron basin.
&&
.PREV DISCUSSION...
Issued at 101 PM EDT Thu Sep 18 2025
AVIATION...
The cluster of showers and isolated thunderstorms over central Lake
Mi are tied to a weak mid level short wave impulse. This feature is
set to move across central Lower Mi and the Tri Cities region mid to
late afternoon at the same time enhanced low level convergence
emerges as a result of the inland advancement of the Saginaw Bay
marine layer. The forcing combined with weak diurnal instability
should lead to additional convective development in the MBS region
late this afternoon. Convection will then push southward during the
evening along a southward advancing cold front. The loss of daytime
instability and some potential lingering mid level capping across
metro Detroit is expected to result in a rapid decrease in the
coverage and intensity of convection as it pushes south, likely
dissipating as it moves into the north Detroit suburbs.
The cold frontal passage this evening will be marked by a wind shift
to the east-northeast. Low level moistening under a deepening
frontal inversion will increase the chances for MVFR based clouds
during the course of the night. MVFR probabilities will be higher
from PTK northward where the frontal inversion will be deeper. Some
IFR ceilings are possible toward daybreak Friday, the probabilities
are not quite high enough to include in the terminals at this time.
For DTW/D21 Convection...A weakening trend is expected this evening
as convection attempts to push into the far northern portions of the
D21 airspace. It is expected that this weakening trend will keep
convective probabilities too low to include in the DTW TAF.
THRESHOLD PROBABILITIES...
* Low in thunderstorms this evening.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
DISCUSSION...KGK
MARINE.......TF/SS
AVIATION.....SC
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.

NWS DTX Office Area Forecast Discussion