Hamburg, Michigan Weather Forecast Discussion

051
FXUS63 KDTX 190003
AFDDTX
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
803 PM EDT Thu Sep 18 2025
.KEY MESSAGES...
- Lingering showers gradually diminish in coverage tonight.
- 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.
&&
.AVIATION...
A backdoor cold front is gaining momentum by merging with a
composite outflow boundary and surging across the Metro Detroit area
at press time. Clusters of showers and a few thunderstorms will wane
in coverage with the loss of daytime instability over the next
couple hours. East-northeast wind gains traction through the rest of
the evening and persists into Friday. Ceiling heights are expected
to lower through the night as a frontal inversion traps low-level
moisture. Highest probability for MVFR conditions is focused in the
Thumb, Tri-Cities, and I-69 corridor but did introduce a brief
period at the Metro Detroit terminals as well given trends in
guidance. A period of early morning IFR will also be possible with
highest confidence at FNT and MBS. Conditions are then forecast to
improve gradually during the daytime Friday.
For DTW/D21 Convection...Remnant late afternoon convective activity
tied to the lake breeze boundary will continue to weaken in
intensity and coverage early in the forecast period. An additional
cluster of showers in the northern D21 airspace will likewise weaken
over the next few hours. Additional thunderstorms are not
anticipated through the rest of the period.
DTW THRESHOLD PROBABILITIES...
* None.
&&
.PREV DISCUSSION...
Issued at 307 PM EDT Thu Sep 18 2025
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.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&
$$
AVIATION.....TF
DISCUSSION...KGK
MARINE.......TF/SS
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at www.weather.gov/detroit.

NWS DTX Office Area Forecast Discussion