727
FXUS63 KDTX 301005
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
605 AM EDT Tue Jun 30 2026

.KEY MESSAGES...

- An Extreme Heat Warning is in effect Tuesday afternoon through
Thursday for high temperatures reaching the mid 90s to 100 degrees
and heat indices in excess of 105 degrees each day.

- There will be little nighttime relief as lows only cool into the
mid 70s with heat index around 80 each night.

- Wednesday and Thursday are the hottest days, however hot and humid
conditions also extend into Friday and the holiday weekend along
with increasing potential for showers and thunderstorms.

&&

.AVIATION...

Strong influence of a large high pressure system centered over the
Ohio valley will maintain a high degree of stability across the
region through tonight. This ensures widespread VFR conditions, with
a limited coverage of high based cumulus expected. A period of
thicker mid level cloud will be possible at times, particularly at
MBS, as convection lifts out of the upper Miss valley and toward
northern lower. Prevailing winds from the southwest, turning
modestly gusty during the afternoon.

D21/DTW Convection... No thunderstorms are forecast for the D21
airspace through Tuesday night.

.DTW THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 250 AM EDT Tue Jun 30 2026

DISCUSSION...

Southeast Michigan now resides securely on the northern periphery of
a sizable heat dome, as the large-scale pattern remains governed by
a sprawling 594 to 596 dam subtropical ridge centered over the Ohio
Valley region. Increasing depth and magnitude to southwest flow
around the western flank of the ridge axis effectively encasing the
region within a high magnitude thermal and moisture profile, as
evident by a projected 850 mb temperature of 23-25c and a dewpoint
encroaching on mid 70s at times. Net result remains a prolonged
extreme heat event featuring near-record temperatures that gets
underway today and persists through at least Thursday. An extreme
heat warning is now active across the region for this window.
Ambient afternoon highs will consistently surge into the mid-to-
upper 90s, with a few locations testing the 100F mark. Combined with
the elevated dewpoint, peak heat index values are forecast to range
between 105 and 110F. Virtually no overnight relief anticipated
within this environment as minimum temperatures struggle to drop
below the mid-to-upper 70s. Risk for organized convective
development remains very low across this period, given the highly
capped environment and unfavorable positioning to witness convection
growing upscale out of the Dakotas and upper MS valley and across
the ridge periphery. A limited opportunity could emerge Wednesday
across the Saginaw valley and thumb, with a subset of the model
solution space initiating convection across northern lower during
this time.

By Friday into the weekend, medium-range deterministic and ensemble
guidance continue to suggest the long wave pattern will undergo a
more notable shift. As the steering flow becomes more zonal along
the international border, successive shortwaves rounding the
northern periphery will gradually, yet effectively dampen, broaden
and suppress the ridge axis into the Ohio valley. Potential for heat
and humidity to remain elevated at least into Friday with the
resident airmass slow to dislodge, before the downgrade in upper
heights combined with increased convective potential likely yields
more typical warmth and humidity for the holiday weekend. A more
receptive underlying environment will exist now for convective
development, but with the usual uncertainty at this time range
regarding potential timing and scale with strong dependence on the
mesoscale evolution upstream. Further refinement of precipitation
chances are likely.

MARINE...

Wind gradually veers to southwest today, allowing a warm front to
advance across Lake Huron today. As the hot and humid air mass
builds in, the gradient will maintain SW wind of 10 to 15 kt today
through Thursday, with gusts generally capped around 20 kt due to
increased stability over the relatively cooler water. There will be
a chance for thunderstorms over Lake Huron today as the front lifts
through, but confidence is low on timing. Areas of fog may develop
over the cooler open waters as well. Additional storms Wednesday and
Thursday will be most likely to occur near northern Lake Huron where
the prevailing storm track will set up along the edge of the more
stable air to the south.

CLIMATE...

Daily Records for the Upcoming Week...

Detroit
                Record High       Record Warm Minimum
Tue June 30       96 (1931)            76 (2018)
Wed July 1        98 (1931)            80 (1931)
Thu July 2        99 (2011)            76 (2018)
Fri July 3       100 (1911)            78 (1911)
Sat July 4       102 (2012)            79 (1921)

Flint
                Record High       Record Warm Minimum
Tue June 30       98 (1933)            76 (2018)
Wed July 1       102 (1931)            72 (2018)
Thu July 2       100 (1931)            73 (2002)
Fri July 3        99 (1921)            73 (1983)
Sat July 4       102 (1921)            76 (1999)

Saginaw
                Record High       Record Warm Minimum
Tue June 30       99 (1964)            77 (2018)
Wed July 1       103 (1931)            78 (1931)
Thu July 2       100 (1931)            73 (2002)
Fri July 3        99 (1966)            76 (1974)
Sat July 4        97 (2012)            75 (2012)

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Extreme Heat Warning from noon today to 8 PM EDT Thursday 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.....MR
DISCUSSION...MR
MARINE.......TF
CLIMATE......MV


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at www.weather.gov/detroit.