754
FXUS63 KDTX 130757
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
357 AM EDT Sun Jul 13 2025

.KEY MESSAGES...

- Slightly cooler and less humid air is slow to arrive behind a weak
cold front today, more noticeable tonight and Monday.

- An uptick in heat and humidity occurs Tuesday as high temperatures
reach around 90 Tuesday afternoon.

- After a dry early week period, showers and thunderstorms return
Wednesday through Thursday.

&&

.DISCUSSION...

Showers percolated south of I-69 and east of US-23 since midnight
within the 850-700 mb moisture axis and ahead of the surface cold
front that is on the way through SE Mi leading up to sunrise.
Remaining activity shifts eastward along and ahead of the front
which itself exits into Ontario and Ohio during early morning,
however cooler and less humid air is slow to arrive during the day.
The frontal passage manages to drop surface Td below 70 for a still
muggy but less oppressive feel, but not dry enough to eliminate
surface based instability. It instead HREF mean MUCAPE increases
back toward 1000 J/kg as peak heating builds this afternoon, a
general trend among the 00Z CAM runs compared to 12Z runs yesterday,
especially from the south end of Lake Huron and along the Ontario
border to western Lake Erie. This makes the afternoon lake breeze a
potential focus for a stray shower or rumble of thunder this
afternoon into the evening.

The inbound surface high pressure struggles to maintain identity
tonight while still able to bring in a more noticeable change in air
mass. Both HREF mean and NBM drop surface Td into the upper 50s most
areas by sunrise, which also wipes the convective slate clean
through Monday. Dry weather also continues Monday night and Tuesday
while the air mass modifies warmer and more humid. The fringe of the
SE US 500 mb ridge is nudged into the southern Great Lakes by
Tuesday afternoon. It supports highs around 90 while mid level dry
air from the central Plains to the Great Lakes is the primary
limiting factor for convection.

Storms appear plentiful in model data from the mid MS/TN valleys
southward and westward into the southern Plains during Tuesday, some
of which are projected to reach Lower Mi Tuesday night and
especially Wednesday. Northern Plains to upper Midwest low pressure
has a cold front stretching back into the central Rockies by
Wednesday morning that is favorably positioned to funnel Gulf
moisture northward while the front becomes the focus for greater
convective organization Wednesday night into Thursday morning.
Consensus of longer range model solutions bring the front through SE
Mi by Friday morning for a chance to start off next weekend with
cooler and less humid conditions.

&&

.MARINE...

A stray shower or rumble of thunder is possible this afternoon near
Lake St Clair and western Lake Erie. Otherwise, dry conditions and
light winds prevail today and through the early week period in the
wake of a cold front and as high pressure builds over the Great
Lakes. The next chance for showers and thunderstorms will enter
Wednesday and Thursday as a prefrontal trough and cold front move
across Michigan. This will bring the potential for some localized
stronger wind gusts with any thunderstorm activity.

&&

.PREV DISCUSSION...
Issued at 1157 PM EDT Sat Jul 12 2025

AVIATION...

VFR skies will be the predominate category through this TAF period.
A cold front currently tracking into western Michigan will continue
to progress east through the early morning hours possibly touching
off a few isolated showers. The main outcome of this front will be a
SCT low VFR to possible brief MVFR deck this morning as it passes
with skies improving throughout the day. Winds turn westerly with
the frontal passage and remain mostly below 10 knots.

For DTW/D21 Convection...No thunderstorms are expected during this
TAF period.

THRESHOLD PROBABILITIES...

* Moderate for ceiling 5000 ft or less with the cold front early
  this morning.


&&

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

$$

DISCUSSION...BT
MARINE.......AM/BT
AVIATION.....AA


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