Expert Forecast Opinion

724
FXUS63 KDTX 161039
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
639 AM EDT Thu Apr 16 2026

.KEY MESSAGES...

- Flood Watch: A Flood Watch remains in effect through this evening.
Several regional rivers are expected to reach or exceed flood stage.

- Severe Potential: Isolated severe thunderstorms are possible
today, capable of producing marginally severe wind gusts and hail.

- Friday/Saturday Transition: Dry conditions on Friday will give way
to rain and a chance of thunderstorms late Friday night through the
first half of Saturday as a strong cold front moves through.

- Weekend Cold Snap: Breezy and much colder Sunday with high
temperatures stuck in the mid-to-upper 40s. A few snowflakes are
possible. Temperatures dropping into the 20s for Sunday night.

&&

.AVIATION...

After a brief break overnight, showers have started moving back in
this morning. There are a pair of mid level systems that will lift
through the area as the resident airmass remains primed to produce
showers and storms for one more day. Strongest storms will be
possible this afternoon into the evening, but there could be
clusters of embedded thunderstorms through most of the day. Timed
out a couple periods of higher confidence with prob30 groups. Later
this evening, the stall front finally makes its way southeast
through the area allowing for drier weather. Guidance then suggests
as skies clear out and northern winds usher cooler air into the
area, that fog will develop. Obs on the north side of the front do
support this so included IFR fog in the tafs for mainly after 06Z
for now but there is potential for LIFR.

DTW/D21 Convection... Current shower activity lifting northeast into
the area has been weak so will leave thunder out for the first batch
of precipitation. Another period of thunderstorm potential remains
worthy of a PROB30 for the afternoon which could offer
isolated strong to severe storms.

.DTW THRESHOLD PROBABILITIES...

* Moderate for ceilings aob 5000 ft this afternoon. Low tonight.

* Low for thunderstorms this morning. Low to medium this afternoon.

* Low for ceilings below 200ft or visibilities below 1/2SM late
tonight.

&&

.PREV DISCUSSION...
Issued at 233 AM EDT Thu Apr 16 2026

DISCUSSION...

A moist airmass remains in place with surface dew points
predominantly in the lower 60s. The primary moisture axis,
characterized by a Theta-E ridge and Precipitable Water (PW) values
of 1.25 to 1.50 inches, will slide east into the Eastern Great Lakes
this morning as the leading Mesoscale Convective Vortex (MCV) passes
through.

A shortwave and its associated surface low moving out of Iowa will
track through central Lower Michigan today. This setup will support
showers driven by deformation and low-level convergence near the
surface low. Mid-level wind fields remain strong, with 45 to 55
knots of 0-6 km bulk shear noted over Southeast Michigan this
afternoon. Surface CAPE is projected to reach 500 to 1000 J/kg with
daytime heating; however, if showers are less prevalent and partial
sunshine develops, instability could exceed these values.

Consequently, an isolated severe threat is warranted, with marginal
wind and hail being the primary concerns. With the surface low
positioned over the northern half of the area this afternoon, there
may be sufficient 0-1 km bulk shear (~20 knots) to support a tornado
threat if instability increases beyond expectations, but chances
look less than 2 percent.

The Flood Watch continues, as storms will be efficient rain
producers. With PW values remaining around 1.0 inch and soil already
saturated, it will not take much additional rainfall to cause
flooding issues.

Much-needed dry weather arrives for Friday as ridging builds at all
levels. This brief reprieve comes ahead of a potent next system that
is expected to bring significant changes to the regional weather
pattern.

Saturday: Latest water vapor imagery highlights a large and potent
upper-level low currently over the Pacific Northwest. The base of
this trough will extend south into the Southern Plains late Friday,
with the primary surface low tracking through the Western Great
Lakes and into Northern Ontario by Saturday morning. This trajectory
will allow a cold front to sweep through Southeast Michigan by early
Saturday afternoon, which should effectively limit the severe
weather threat and taper off showers as surface ridging builds in
behind it.

There is currently excellent model consensus (NAM, Canadian, Euro,
and UKMET) regarding this frontal timing. Only a few Euro ensemble
members are suggesting the development of a secondary low, which
would be the only scenario that slows the frontal passage.

Strong cold advection will lead to a chilly Sunday. Temperatures at
the 850 MB level are projected to bottom out at or below -10C by
Sunday evening, which will keep surface high temperatures struggling
to even exit the 40s during the day. Steep low-level lapse rates
will also support isolated to potentially scattered rain or melting
snow showers through Sunday afternoon. As skies clear and winds
diminish Sunday night, temperatures are expected to dip into the 20s.
Consequently, a Freeze Warning will likely be required for the
region.

MARINE...

A trough moves into the area today maintaining periodic rounds of
showers/storms with an isolated storm mainly over the southern Great
Lakes having the potentially to be severe. System peels away from
the region late tonight ushering in a brief period of high pressure
Friday bringing lighter winds and dry conditions. Broad low pressure
tracking through northern Ontario will then drag a respectable cold
front through the Great Lakes daytime Saturday generating yet
another round of showers and thunderstorms, some of which have the
potential to be severe. Moderate to strong cold advection follows
for Sunday with northwest winds peaking in the lower 30 knots. While
a couple gusts near gales are possible, overall potential remains
low (<30%).

HYDROLOGY...

Given antecedent rainfall and already saturated soils from a wet
spring, the Flood Watch remains in effect for all of Southeast
Michigan through this evening. Significant rises are expected on
regional waterways, with the Tittabawassee, Saginaw, Cass, and
Shiawassee Rivers forecast reach/exceed flood stage.

Showers today, with embedded thunderstorms, will lead to localized
heavy downpours. While most locations will receive less than 1 inch
of rain, the primary concern is thunderstorm training (multiple
storms moving over the same area). This could lead to much higher
rainfall totals and a heightened risk for significant flooding.
Confidence in the exact placement of these heavier rain corridors
remains low, but the overall environment remains conducive to
efficient rainfall rates.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Flood Watch through this evening 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.
&&

$$

AVIATION.....DRK
DISCUSSION...SF
MARINE.......KDK
HYDROLOGY....SF


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