787
FXUS63 KDTX 031052
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
652 AM EDT Thu Jul 3 2025

.KEY MESSAGES...

- Drier conditions today through Saturday with a slight chance for a
shower or thunderstorm today and tomorrow.

- Warm up for the holiday and this weekend with highs in the upper
80s on Independence Day and low 90s Saturday and Sunday.

- Chance (40-50%) for showers and thunderstorms in the Sunday
afternoon - Sunday night time period.

&&

.AVIATION...

Deep northwesterly flow in place will carve out a quasi stationary
frontal boundary over Southeast Michigan today. Combination of
subsidence in the 10.0 to 19.0 kft agl layer will lead to
predominately VFR dry conditions today. There is some model signal
in a wave rolling along this frontal boundary with some potential
for a little richer 700mb moisture. During peak heating there will
be a chance for an isolated shower or thunderstorms at the Detroit
terminals, after 21Z. VFR conditions tonight with wind directions
trending to the east.

For DTW/D21 Convection... A low chance of storms this afternoon.

THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less in the afternoon with
  thunderstorm activity.

* Low for thunderstorms this afternoon.

&&

.PREV DISCUSSION...
Issued at 351 AM EDT Thu Jul 3 2025

DISCUSSION...

Hudson Bay low pressure will continue to govern conditions over SE
Michigan today. This begins with the nose of a cyclonic ~80 knot jet
streak that is pushing across Lake Huron this morning. This trough
quickly slides to the east this morning in favor of increasing mid-
level subsidence that establishes a capping inversion by the time
peak heating occurs. Overall this should suppress most convection,
although remnant cyclonic influence affords just enough low-level
convergence to include a slight chance mention of a shower/storm.
This is observed in nearly all hi-res models/HREF but with low
coverage. Seasonable conditions expected otherwise with daytime
highs in the mid 80s, although upper 70s readings in the Thumb
reflect the inland penetration of the Lake Huron lake breeze.

Post-lake breeze flow will only be reinforced tonight as high
pressure slides over northern Michigan and settles into Ontario,
scouring out the instability plume. The strengthening surface
anticyclone will be complemented by broad height rises as the H5
ridge strengthens to 594 dam and pivots overhead. Similar to today,
these processes will all favor deep layer stability which affords
overall dry and sunny conditions for most of the holiday. Low level
winds become increasingly veered and begin to draw a warm front into
the cwa during the afternoon/evening, which could trigger a few
showers and storms on the west side of the state. That said, the
remnant stable layer and limited column moisture locally should
again support a sufficient cap to prevent much convective activity.
The warm front will, however, boost temperatures and humidity with
highs to 90 degrees around Adrian/Ann Arbor and dewpoints into the
60s.

Heat and humidity persist into the holiday weekend with temperatures
climbing above 90 degrees and heat indices in the mid-90s. Another
dry day is expected on Saturday, but upstream return flow creates a
stream of Gulf moisture that reaches SE Michigan on Sunday. PW
values above 2.0 inches will be possible with this airmass. Showers
and thunderstorms become likely in this environment as a mid-level
shortwave and cold front supply synoptic ascent. Mid-level flow
however remains unimpressive (35-40 knots) given the low amplitude
nature of the wave. Temperatures then cool back toward normal early
July standards (mid 80s) once the front passes through early next
week.

MARINE...

A weak cold front drops through the region early this morning
setting up northwesterly flow for the first part of the day. Weak
high pressure is quick to follow as its drifts directly over Lake
Huron resulting in further weakening of already lighter flow and
more variable wind directions. An isolated shower/t-storm is
possible on the periphery of the high towards Lake Erie this
afternoon-evening however the vast majority of the region stays dry.
Hotter, more humid air returns this weekend as a warm front lifts
through the central Great Lakes late Friday-Saturday. Moderate SW
winds follow the front with gusts peaking around 20kts, particularly
over the central portions of Lake Huron. A cold front sagging into
the Great Lakes then brings storm chances latter half of Sunday
through Monday.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....CB
DISCUSSION...MV
MARINE.......KDK


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.