818
FXUS63 KDTX 200722
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
322 AM EDT Sat Jul 20 2024

.KEY MESSAGES...

* High pressure ensures another day of dry conditions with high
  temperatures in the low 80s.

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

* Better potential for showers and thunderstorms middle of next week
  as weak low pressure and a cold front track through the northern
  Great Lakes.

&&

.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.

&&

.PREV DISCUSSION...
Issued at 1139 PM EDT Fri Jul 19 2024

AVIATION...

High pressure extending across the southern Great Lakes will
maintain light and variable winds through the morning. This high
pressure system will dominate into Saturday night. The associated
dry air will limit cloud coverage to just scattered diurnally driven
cu.

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

DTW THRESHOLD PROBABILITIES...

* None.


&&

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

$$

DISCUSSION...MV
MARINE.......BT
AVIATION.....SC


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