621
FXUS63 KDTX 201724
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
124 PM EDT Sat Jul 20 2024

.KEY MESSAGES...

* Low chance for a showers and possibly thunderstorms Sunday and
  Monday afternoon.

* Better potential for showers and thunderstorms middle of next week.

&&

.AVIATION...

Dry and stable low level conditions persist through tonight as high
pressure maintains control. This ensures VFR conditions hold, while
winds remain light and variable. Broad coverage of higher based
diurnal cu at scattered to perhaps briefly broken coverage will
linger through the latter half of the day before fading with loss of
daytime heating.

For DTW/D21 Convection...No convection is expected through the TAF
period.

DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 322 AM EDT Sat Jul 20 2024

DISCUSSION...

A stagnant upper level pattern, characterized by semi-permanent high
pressure over SE CONUS and a slow-moving upper low near Hudson Bay,
affords little change to local conditions from yesterday to today.
Plenty of solar insolation is expected again to support a well-mixed
boundary layer with temperatures reaching into the low 80s. Similar
diurnal cumulus response expected as well, although with an added
layer of high-based cirrus stemming from convective cloud debris
originating in the Great Plains.

Looking at the CONUS-scale, GOES-16 mid level WV loop depicts the
two disturbances that will impact SE Michigan in the coming days.
The first of these is a pair of shortwaves over southern Minnesota,
which will evolve into a cut off low today and slowly pivot into the
Great Lakes early next week. The second is the deformation axis
which will supply a band of enhanced theta-e to central lower MI
beginning on Sunday. The added moisture boost creates weak
instability on the order of ~500 J/kg (MUCAPE) during peak heating,
enough to trigger isolated to scattered showers across northern
portions of the cwa Sunday afternoon. An isolated (non-severe)
thunderstorm cannot be ruled out.

Guidance signals for the upstream cut off low to open up and slowly
get absorbed into the mean flow early next week. There are still
major differences in the temporal and spatial placement of the upper
low-wave transition. Precipitation chances and coverage will
generally be tied to the interplay between lingering moisture and
survival of the upper low circulation into lower Michigan. As of
now, another low chance for showers exists Monday afternoon which
will have a diurnal component tied to a broader plume of weak
instability. A more dynamic system arrives mid-week, supportive of
more widespread shower and thunderstorm chances. Upper trough
influence throughout the forecast period maintains temperatures in
the low to mid 80s.

MARINE...

A broad expanse of surface high pressure centered on Lake Erie
ensures favorable marine conditions across Great Lakes during the
early part of the weekend. Benign conditions then continue even as a
weak cold front settles into northern Lake Huron Saturday night and
across the south half during Sunday. The front brings a minimal
temperature change and supports just a stray shower along and near
the boundary leaving the SW to NE wind shift as the weather
highlight. The directional wind shift is notable but wind speed
remains light for a low impact wave pattern Sunday followed by the
front washing out in favor of weak high pressure by Monday.

&&

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

$$

AVIATION.....MR
DISCUSSION...MV
MARINE.......BT


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