Expert Forecast Opinion

511
FXUS63 KDTX 220939
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
539 AM EDT Mon Jun 22 2026

.KEY MESSAGES...

- Showers with a rumble of thunder continue into early morning,
mainly south of the Tri Cities and northern Thumb, transitioning to
light rain before ending toward noon.

- Dry weather moves in this afternoon and continues tonight and
Tuesday.

- Slightly cooler than normal temperatures continue through mid to
late week.

- The next chance of rain arrives Wednesday and Wednesday night.

&&

.AVIATION...

Rainfall coverage and rates will continue to decrease through the
morning hours as Ohio Valley low pressure weakens and exits
eastward. Meanwhile, high pressure builds into the Upper Midwest
helping to stabilize Lower Michigan. Uncertainty remains as to how
long MVFR fog/rain lingers today before mixing processes and the
influx of continental air work to dry out the lower portion of the
column. VFR conditions should expand across all terminals by midday
with rain-free weather expected for the afternoon and evening hours.
Initial midday cumulus response could linger within the upper end of
MVFR until later in the day. A bit breezy with winds organizing out
of the north, gusting to around 20 knots. Skies clear out early
night with decreasing winds.

D21/DTW Convection...No thunderstorms expected today and tonight.

.DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 ft most of today.

&&

.PREV DISCUSSION...
Issued at 353 AM EDT Mon Jun 22 2026

DISCUSSION...

Clusters/bands of showers are in progress over southern Lower Mi
primarily associated with the strong mid level circulation that is
the parent to Ohio valley surface low pressure. The system is still
supporting a wide range of convection from severe thunderstorms
along and ahead of the surface fronts, to elevated but still
cellular showers north of the surface low, to the clusters/bands
across much of southern Lower Mi. Lightning has been absent north of
the IN/OH border since midnight, however rainfall rates have still
been quite productive as the leading stratiform component last
evening quickly transitioned to clusters/bands as 700 mb isentropic
lift and frontogenesis activated ahead of the 500 mb circulation.
The most intense concentration of clusters and banding produced
event rainfall totals in the 0.75 to 1.25 inch range from northern
IN into SW Lower Mi based on surface observations and radar
estimates since 00Z last evening up to press time.

There is still an additional round of showers and a rumble of
thunder yet to go as radar coverage steadily fills in over central
IN/OH. This is where the low level jet activates new convection
within the 850-700 mb theta-e gradient before veering eastward with
the surface low center. HREF and REFS 3 hr PMM QPF capture this
reasonably well and show it grazing the SE MI area south of I-94
from now through sunrise. After that, precipitation rate diminishes
while coverage is maintained by mid/upper level deformation from
about the mid Thumb shoreline to Lansing during early morning. There
is good agreement in the 00Z models that all rain ends in SE Mi
around Noon.

Satellite imagery upstream across the northern Great Lakes then
supports a decreasing cloud trend over SE Mi this afternoon,
although it may take until late afternoon to clear Detroit.
Decreasing clouds is mainly associated with larger scale subsidence
trailing the morning low pressure system as low level northerly flow
is just slightly cooler and less humid. The inbound high pressure
air mass gains greater presence late tonight and Tuesday as the
mid/upper level short wave ridge builds over the Midwest while
keeping the surface ridge to our west. This maintains moderate
northerly wind in the low levels that is still mild enough for a
fair weather cumulus field in the afternoon. Guidance highs in the
mid to upper 70s further supports this air mass just maintaining the
already slightly below normal temperature pattern of recent days.

High pressure holds Tuesday night, but just barely, as the long wave
mid/upper air pattern remains less amplified and progressive. This
has the current Canadian Rockies system reaching the Great Lakes
without much fanfare Wednesday and Wednesday night. Model consensus
tracks the surface low through the northern Great Lakes which sets
up a standard warm front/cold front progression across SE Mi for our
next chance of showers and thunderstorms. This is another system
that brings little change of air mass as guidance temperatures hold
in the mid to upper 70s post front on Thursday. This could change as
extended range models indicate a larger pattern shift occuring next
weekend resulting in a large closed low over the Rockies and a
downstream ridge over the Midwest. Guidance high temperatures in the
mid 80s are offered in SE Mi by Sunday.

MARINE...

A compact low pressure system will travel east across the Ohio
Valley through the morning. This will sustain east to southeast flow
across Lake Erie, and wind gust potential around 25 knots along with
elevated wave heights. A Small Craft Advisory remains in place. Some
isolated wind gusts 20 to 25 knots will be possible across Lake St.
Clair this morning, with lower magnitude wind speeds across Lake
Huron and the Saginaw Bay. Widespread rain continues across the
southern Great Lakes, tapering off in the late morning to early
afternoon. Wind direction backs north to northwest in the wake of
the low through the early week period as high pressure builds in.
Lighter winds are expected tomorrow and Wednesday.

HYDROLOGY...

Widespread showers are in progress over SE Mi generally south of the
Tri Cities and northern Thumb. There is a chance of locally heavy
rainfall in this pattern through early morning, especially toward
the Ohio border. Event total amounts of 0.5 to 1.0 inch are likely
along and south of I-69, with a chance of localized totals around
1.5 inches mainly south of Detroit to the Ohio border before
intensity diminishes considerably around sunrise. These rainfall
totals and time ranges suggest the potential for flooding will be
limited to ponding of water on roadways and other prone areas.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 5 PM EDT this afternoon for MIZ083.

Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...Small Craft Advisory until 5 PM EDT this afternoon for LEZ444.

&&

$$

AVIATION.....KGK
DISCUSSION...BT
MARINE.......AM
HYDROLOGY....BT


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