Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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979
FXUS63 KDTX 121917
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
317 PM EDT Sat Jul 12 2025

.KEY MESSAGES...

- Temperatures in the mid 80s tomorrow, upper 80s Monday, then
reaching around 90 degrees on Tuesday.

- Dry start to the week, but showers and thunderstorms likely return
Wednesday-Thursday.

&&

.DISCUSSION...

Broken line of strong to marginally severe thunderstorms went up on
the prefrontal trough around noon, earlier and more extensive than
many of the hires solutions. Dew pts dropping into the mid to upper
60s and surface ridging moving in late this afternoon has pretty
much ended the severe threat, as mid level cold pool and much better
wind shear over Western Great Lakes will not arrive in time before
the sun sets. Still, the cold front may be able to muster a couple
more showers and thunderstorms in the evening with some residual low
instability left over.

Upper level trough axis swings through tomorrow, but extremely dry
mid levels (40-50 C dew pt depressions at 700 MB) look to prevent
any activity from going up, except perhaps right near the southern
Michigan border.

Upper level ridge (591-592 DAM at 500 MB) axis then builds over the
region early next, promoting dry but hot weather, with temps likely
reaching 90 degrees on Tuesday.

A wet pattern then looks to be setting up for Wednesday-Thursday as
moisture streams up from Gulf Coast States/Southern Plains, in
response to a fairly strong upper level wave/trough swinging through
the northern Rockies and into the Western Great Lakes by Thursday.
Euro ensembles indicating at least a 60 percent chance of a tenth
or inch or more of qpf in Wednesday-Thursday time frame.

&&

.MARINE...

The thunderstorm threat has generally receded although some isolated
development remains possible through the evening hours. Otherwise,
dry conditions prevail in the wake of the ongoing cold front passage
which brings light winds with gust potential holding below 20 knots.
The next chance for showers and thunderstorms will arrive through the
midweek period by Wednesday as an upper-level disturbance arrives
over the Great Lakes.

&&

.PREV DISCUSSION...
Issued at 156 PM EDT Sat Jul 12 2025

AVIATION...

Several gravity waves emanated away from the trough over the Midwest
this morning initiated convection a few hours earlier than
anticipated today. With the lead line exiting the area at press
time, we look toward the next few hours for any additional
convection. The next line has initiated over MBS and will now work
eastward but confidence in how this line will act over the next few
hours is low. Will hedge the tempo forward in time a few hours
thinking that this next line may be the final chance this evening as
drier air is spreading across SW Lower toward the area which will
further lower chances. So, tempo TSRA through about 20-21Z with only
isolated activity after that. The cold front will work through
tonight possibly touching off a few showers, otherwise expecting a
sct low VFR/MVFR deck tonight before skies improve Sunday. Gusty
winds this afternoon will decrease and turn westerly tonight with
the frontal passage.

For DTW/D21 Convection...There remains a chance of thunderstorms
this afternoon mainly before 21Z. Only isolated activity is expected
this evening with mainly dry conditions tonight. Gusty winds will be
the primary threat with any storm.

THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less outside of thunderstorms today and
  this evening. Moderate with the cold front late tonight.

* Low for thunderstorms this afternoon.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422.

Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

DISCUSSION...SF
MARINE.......AM
AVIATION.....DRK


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