554
FXUS63 KDTX 010945
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
545 AM EDT Tue Jul 1 2025

.KEY MESSAGES...

- The potential exists for thunderstorms across Saginaw Bay and the
Thumb Wednesday afternoon. There is a Marginal risk (1 out of 5) for
severe weather.

- Classic summer weather pattern during the middle to end of the
week with daytime temperatures hovering in the low to mid into the
80s.

- Warmer and more humid conditions are anticipated Friday. The
potential for more widespread shower and thunderstorm activity is
expected Saturday night.

&&

.AVIATION...

Remnant frontal zone continues to pump mid-level moisture into
southern portions of the airspace, resulting in a cloud deck around
10.0 kft agl. The cloud shield is expected to slowly drift east
through the morning, while diurnal cumulus develops in the
afternoon. Cloud bases are forecast to reach 6.0 kft agl. Otherwise,
light southwest flow veers to the west, peaking around 10-12 knots
this afternoon.

For DTW/D21 Convection...No thunderstorms expected today or tonight.

 THRESHOLD PROBABILITIES...

* Low for cigs aob 5kft this afternoon and early evening.

&&

.PREV DISCUSSION...
Issued at 319 AM EDT Tue Jul 1 2025

DISCUSSION...

Composite 580dam H5 trough axis will push to the east of the
forecast area between 12z-18z today. The net result will cause
surface ridging to expand out of the central Plains into Lower
Michigan and opening the door to broad northwest flow. Plan view
perspective of system relative flow on isentropic downglide exhibits
deep downglide between 900-600 mb or between 5.0 and 17.0 kft agl.
There will likely be some cumulus around given the recent rainfall,
but the dry sounding supports a lot of sunshine. Highs today in the
lower 80s right at seasonal average.

Busy and messy pattern catches the area again on Wednesday as broad
troughing shows obvious amplification over the western and central
Great Lakes. Big picture view highlights upper level jet streaks
digging into the area from the north and low level thetae advection
across Wisconsin and into Lower Michigan. A little tricky this far
east as system relative trajectories want to remain anticyclonic. A
good signal for the combination of convective outflow and backdoor
cold front off of Lake Huron leading to showers and thunderstorms
over portions of the forecast area Wednesday afternoon. Best NWP
signal (3km nam and HRDPS/RGEM) point to Saginaw Bay and Thumb. The
potential does exist for isolated severe weather with SBCAPES of
1000-1500 J/kg and 0-6km bulk shear of less than 30 knots. The
latest Swody2 has a portion of the northern cwa designated in a
Marginal risk for severe weather.

Uptick in heat and humidity is anticipated for Thursday and Friday
with highs in the 80s and dewpoints in the 60s. Large amplitude
ridge axis will be immediately upstream. This places southeast
Michigan immediately in the anticyclonic break and in vicinity of
any ridge riding shortwave energy. Cannot rule out precipitation
chances but nothing looks organized from this vantage point.

Upper level ridge will move rapidly across the area as models show a
likelihood that it will be rolling over or flattening as it tracks
through. Very warm conditions are expected Saturday with upper level
forcing showing high potential for widespread precipitation sometime
Saturday night or Sunday. Do think the Sunday temperature forecast
is highly uncertain.

MARINE...

A cold front departs the region this morning with westerly wind
peaking near 15 to 20 kt this afternoon. High pressure over the
Midwest maintains a weak gradient with prevailing light westerly
wind over the Great Lakes through mid-week. A weak cold front then
sinks across the region late Wednesday into Thursday with post-
frontal northwest wind staying light. High pressure builds directly
across the region Thursday night to maintain light wind and waves
into Friday.

&&

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

$$

AVIATION.....MV
DISCUSSION...CB
MARINE.......TF


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