Expert Forecast Opinion

461
FXUS63 KDTX 082312
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
712 PM EDT Wed Apr 8 2026

.KEY MESSAGES...

- A slow moving cold front brings and band of light rain showers
with broken coverage across the area Thursday.

- Another round of rain showers with wider coverage and greater
intensity develops late Thursday night and Friday morning.

- Dry weather and cooler but still near normal temperatures follow
behind the front Friday afternoon and Saturday.

- Warmer temperatures move in Sunday and Monday but also with an
active rainfall pattern early next week.

&&

.AVIATION...

A very dry southeasterly trajectory will ensure VFR precipitation
free conditions through 06z tonight. A narrow axis of midlevel
moisture transport will then push into Southeast Michigan late
tonight in response to compact low pressure system passing through
Northwest Ontario. Model progs show significant weakening of both 850-
700mb frontogenesis as the frontal zone moves through the area 09-
15z. Model soundings support very poor midlevel lapse rates and a
struggle to hold saturation below 6.0 kft agl. Preference is for
TEMPO MVFR conditions with light rain. Southwest winds of 15 to 25
knots anticipated Thursday afternoon in the wake of the
precipitation.

.DTW THRESHOLD PROBABILITIES...

* Moderate for ceilings at or below 5000 ft Thursday morning.

&&

.PREV DISCUSSION...
Issued at 347 PM EDT Wed Apr 8 2026

DISCUSSION...

Morning sun helped lift temperatures from frosty morning lows in the
20s before a brief mid level cloud increase from the west which has
since dissipated to just patchy coverage. Extra sunshine is helping
lift temperatures more into the lower 50s at mid afternoon, although
SE wind gusting in the 20 mph range feels cooler and the onshore
direction is limiting readings the to 40s near Lake Huron. The now
departing mid level clouds represent warm advection in progress
across the Great Lakes that continues tonight. Evening temperatures
settle into or remain in the 40s and then rise into the lower 50s
after midnight as surface wind veers SW and the warm sector of
northern Ontario low is drawn into the region.

Dry weather holds for much of tonight as the milder air moves into
Lower Mi, and until a band of rain showers reaches the Tri Cities
toward sunrise. This occurs within the moisture axis also drawn
northward by SW flow ahead of the cold front trailing the Ontario
surface low. Model depictions of the lower to mid level theta-e
ridge still indicate a narrow and sharp structure within a 50 kt low
level jet across the upper Midwest and western Great Lakes this
evening. This is where moisture transport, daytime instability, and
short wave/frontal forcing all align to produce a more solid and
more intense band of showers and scattered thunderstorms. All of
this changes as the band reaches central Lower Mi and the Tri Cities
toward sunrise. The moisture advection is over, timing is at the
nocturnal instability minimum, and the boundary is trending
frontolytic on the south flank of the mid level wave. Loss of this
larger scale organization supports the diminishing trend in rainfall
rate shown in hi-res and regional deterministic models as the front
settles through SE Mi during Thursday.

Model projections in today`s 12Z cycle maintain solutions that show
the front stalling across IN/OH Thursday night as the next 500 mb
short wave arrives in the Midwest. This wave reactivates a larger
band of rain showers at mid levels of the frontal zone that is timed
to move into central and SE Mi mainly after midnight which then
lasts through Friday morning. Nocturnal timing in this case is
favorable for low level jet intensification downstream and along the
850-700 mb frontal zone leading to a flare-up of elevated
convection. The general forecast trend shows a slight northward
shift in the rain/snow line and in the position of the consensus QPF
axis, both associated with a similar northward shift on the track of
the mid level wave and pressure reflection along the surface frontal
zone. Rainfall amounts still range widely among deterministic
solutions for the 6 hour period ending 12Z Friday and are generally
less than 1 inch for the entire 12 hour event ending 18Z Friday,
including a tendency to shift new elevated convection toward the
surface front Friday morning. Localized 1 inch totals are mentioned
in the Hydrology section as high end amounts with low predictability
depending on occurrence and location of isolated thunderstorm
clusters. Overall event rainfall totals are less than 0.5 inch in AI
solutions and ECMWF/GFS ensemble means, which suggests leaning the
forecast toward lower values of NBM QPF in the 0.5 to 0.75 inch range
before the system exits Friday afternoon.

Eastward passage of the progressive 500 mb wave and larger scale
trough axis drives the front much farther south into the Ohio valley
by Friday evening. NW confluent flow and a surge of surface high
pressure follows to maintain dry weather Friday night and Saturday.
The inbound high pressure air mass is projected to be just slightly
cooler in temperature guidance that carry highs in the 50s for
Saturday, right around normal for early to mid April. Another round
of warm advection is well underway across the Great Lakes by early
Sunday as the next low pressure system organizes in the Plains
states. This system is associated with a southern stream 500 mb
trough over the Rockies that generates deep SW flow of Gulf moisture
into the Great Lakes meaning warm temperatures but also an active
rainfall pattern for early next week.

MARINE...

Southerly flow strengthens tonight across the central Great Lakes as
surface low pressure progresses across Ontario, causing gradient
winds to increase above 20 knots for much of Lake Huron. A 60 knot
low level jet associated with the system also moves in overhead, but
low-level stability should limit strong gusts from mixing down to
the surface. Gusts should generally be capped below 35 knots, with
elevated wave heights being the main marine concern. The wave
response will be sufficient to exceed Small Craft Advisory criteria
for the southern Huron nearshore zones, therefore an advisory
remains in effect. Also, a few gusts to gales cannot be ruled out,
especially over the northern Huron waterways, but infrequency should
still preclude any gale headlines. The low eventually draws a cold
front across the region late tonight into Thursday resulting in
several rounds of showers, with low potential for a couple embedded
thunderstorms.

A wave lifting out of The Plains leads to additional opportunities
for showers and perhaps a thunderstorm Thursday night and Friday,
with some light snowfall more likely for the north/central Huron
basin. High pressure then builds out of the Upper Midwest to start
the weekend with drier and weaker northwest flow. Active weather
will be possible again Sunday through Tuesday due to several passing
disturbances. Potential exists for gusts to gales late Sunday into
Monday.

HYDROLOGY...

A cold front brings a band of rain showers first into the Tri Cities
area early in the morning which then moves to the south and east
across the rest of SE Michigan during the day. Broken coverage of
showers produces rainfall totals generally less than 0.2 inch as the
band weakens while moving through the region and then exits by late
afternoon. A second round of showers develops mainly after midnight
Thursday night and lasts through Friday morning. This system brings
higher rainfall amounts over a wider area averaging about 0.5 inch
in a 6 to 12 hour time window. There is a chance for localized
totals near 1 inch where embedded thunderstorms occur before this
pattern also exits southward and eastward Friday afternoon. Flooding
potential remains low with this event, although the new rainfall
could slightly delay drainage from river and stream systems after
the heavy rain that occurred last weekend.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 4 PM EDT Thursday for LHZ421-422-441>443.

Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....CB
DISCUSSION...BT
MARINE.......KGK
HYDROLOGY....BT


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