Expert Forecast Opinion

260
FXUS63 KDTX 150813
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
413 AM EDT Wed Apr 15 2026

.KEY MESSAGES...

-Persistent Flood Risk: A Flood Watch remains in effect through
Thursday night as multiple rounds of showers and thunderstorms cross
a stalled frontal boundary. Previous rainfall has saturated soils,
making the region highly susceptible to additional runoff.

-Severe Potential: A Marginal to Slight Risk for severe
thunderstorms exists this afternoon and evening, with another
isolated threat focused toward the Michigan/Ohio border on Thursday.
The primary hazard remains damaging wind gusts within any organized
convection.

-Dry Friday followed by a Cold Weekend: Conditions dry out briefly
on Friday before a strong cold front brings rain and possible
thunderstorms on Saturday. The weekend concludes on a windy and much
colder note Sunday, with temperatures plunging into the 40s.


&&

.DISCUSSION...

A stalled-out frontal boundary remains draped across southern Lower
Michigan early this morning. Water vapor imagery reveals at least
two distinct upper-level waves currently over the Plains that are
progged to work through the Great Lakes region through Thursday
night.

The 00z RRFS and 00z 3KM NAM both provided a reasonable depiction of
the convective line that rolled through Southeast Michigan earlier
this morning. However, notable differences remain regarding the
timing and extent of redevelopment today. Leaning toward the RRFS
solution, expect a brief lull by mid-morning as the initial wave
exits. This reprieve will be short-lived, as high-resolution
guidance suggests rapid airmass recovery by early afternoon. With
SBCAPE progged to rebound into the 10001500 J/kg range amidst 40-
knot bulk shear, additional discrete cells or multicell clusters are
favored to develop along residual outflow boundaries. The Day 1 SPC
outlook maintains a Slight Risk for southern areas, with damaging
wind being the primary hazard.

The RRFS remains aggressive for Thursday as well, highlighting a
secondary mid-level trough lifting into the Great Lakes. This
feature will provide stronger synoptic forcing for widespread,
efficient precipitation. Relief finally arrives on Friday as a
transitory period of mid-level ridging and surface high pressure
provides a much-needed reprieve from the active weather.

Attention then turns to a potent longwave trough ejecting out of the
Pacific Northwest and arriving over the weekend. A deepening surface
low is progged to track through the Upper Mississippi Valley on
Friday, dragging a cold front through Southeast Michigan on Saturday
(most likely during the early afternoon per the 00z Euro). Any delay
in frontal timing could allow for stronger southwest winds ahead of
the boundary, with gusts potentially reaching 40 mph given the 4050
knot jet at 850 mb. While widespread showers may help limit
instabilitykeeping MUCAPE values under 1000 J/kgthe strong wind
fields will maintain a marginal severe threat.

Post-frontal cold air advection (CAA) looks robust for the tail end
of the weekend, with 850 mb temperatures bottoming out around -10C
by Sunday morning. Breezy to windy conditions will make for a "raw"
day, as highs struggle to exit the 40s under a persistent deck of
stratocumulus. Steep low level lapse rates will also support
isolated to possibly scattered rain or snow showers through Sunday
afternoon.

&&

.MARINE...

Overnight showers and thunderstorms depart this morning while an
unsettled pattern remains in place today and Thursday. Additional
rounds of showers and storms are possible throughout the day, with
similar strong to severe concerns as the past few days. Localized
winds in excess of 35 knots, erratic waves, and large hail will all
be possible. Familiar wind pattern today and Thursday as the warm
front holds near Saginaw Bay, causing winds to back toward the east
north of the front. Some relief to the wet pattern is expected
Friday before another low ripples through Saturday, drawing a strong
cold front across the region. This will elevate winds on a more
widespread basis compared to the more localized wind potential in
thunderstorm activity through the work week.

&&

.HYDROLOGY...

Rainfall totals up to 2 inches were observed earlier this morning
across portions of the M-59 corridor and the Saginaw Valley. Given
this antecedent rainfall and already saturated soils from a wet
spring, the Flood Watch remains in effect for all of Southeast
Michigan through Thursday night. Significant rises are expected on
regional waterways, with the Tittabawassee and Saginaw Rivers
forecast to reach flood stage; the Shiawassee River also remains a
point of concern for potential flooding.

Multiple rounds of showers and thunderstorms will continue
intermittently through Thursday evening. While broad-scale
forecasted rainfall totals today through Thursday are generally
around 1 inchwhich typically would not trigger widespread
floodingany focused areas of convection could significantly over-
perform. The primary concern is for thunderstorms to "train" over
the same localized areas, leading to much higher rainfall totals and
a heightened risk for flash flooding. Confidence in the exact timing
and placement of these heavier corridors remains low, but the
overall environment remains highly conducive to efficient rainfall
rates.

&&

.PREV DISCUSSION...
Issued at 159 AM EDT Wed Apr 15 2026

AVIATION...

Strongest line of convection has passed through PTK southward and
will impact the Detroit taf sites for the first hour or two of the
forecast. TSRA may continue a bit after that within the trailing
stratiform before showers taper off around 10-12Z. Warm front
remains draped across the area with potential showers and
thunderstorms today and into tonight. Tried to time out some higher
confident windows of time based on hires models, but those times may
shift. Outside of variable winds during convection, they should
largely be southwesterly around 10 knots.

DTW/D21 Convection... A line of thunderstorms will move across DTW
between now and 09z. Showers will continue with some embedded
thunder possible through the early morning. After a potential brief
lull, additional rounds of showers and thunderstorms will exist
through the day.

DTW THRESHOLD PROBABILITIES...

* High for ceilings aob 5000 ft tonight. Medium Wednesday morning.

* Medium to high for thunderstorms tonight between 04z and 09z.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Flood Watch through late Thursday night for MIZ047>049-053>055-
060>063-068>070-075-076-082-083.

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

$$

DISCUSSION...SF
MARINE.......MV
HYDROLOGY....SF
AVIATION.....DRK


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