215
FXUS63 KDTX 030751
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
351 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.

&&

.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.

&&

.PREV DISCUSSION...
Issued at 1202 AM EDT Thu Jul 3 2025

AVIATION...

A stray shower or thunderstorm remainS possible during the late
night based on activity still percolating upstream toward the surface
cold front, although coverage this far south has low predictability
through the morning. Larger scale conditions support VFR for SE MI
under and high debris clouds from the evening storms while the cold
front remains on schedule to settle southward. It is expected to
reach the MBS area during the morning and then stall/wash out toward
the Ohio border in the afternoon. Broken VFR ceiling near 5000 ft is
likely in and near the frontal zone with a renewed chance of storms
focused closer to the DTW corridor into Thursday evening.

For DTW/D21 Convection... A chance of storms returns Thursday
afternoon.

THRESHOLD PROBABILITIES...

* Moderate for ceiling 5000 ft or less in the afternoon.

* Low for thunderstorms in the afternoon into Thursday evening.


&&

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

$$

DISCUSSION...MV
MARINE.......KDK
AVIATION.....BT


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at www.weather.gov/detroit.