682
FXUS63 KDTX 271942
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
342 PM EDT Thu Jun 27 2024

.KEY MESSAGES...

- Cool tonight with lows dropping into the mid 40s to mid 50s.

- Next chance of showers and strong thunderstorms will be on
Saturday.

- Cool and dry weather for the second half of the weekend.

&&

.DISCUSSION...

Quiet end to the week with below normal temperatures brought to us
by a Canadian surface high sliding across the region. Thermal trough
should be passing east by this afternoon but may be too late to be
realized at the surface with some highs likely barely breaking 70,
which is around 10 degrees cooler than normal for late June.
Dewpoints this afternoon have fallen into the 40s across most of the
state and some upper 30s across northern MI. As the high centers
itself over the state tonight, this sets the state for some cool min
temps as some cooler locations dip into the upper 40s.

High pressure remains in control Friday but will be centered over
the east coast by morning allowing for southeasterly winds to start
advecting some warmer air back into the region. A good deal of sun
outside of some high cloud debris, plus the southerly flow will help
max temps rise back into the upper 70s.

Attention then turns toward the Friday night to Saturday part of the
forecast when some mid level energy and surface cold front pass
through the region bringing the next chance of showers and
thunderstorms. The current upper level ridge over the region gets
flattened by a stronger low up over northern Ontario. A second
trough dropping into the northern Plains will then send a few
shortwaves through the flat, westerly flow through the Great Lakes
Friday and Friday night. This will mostly result in little to no
precip at the ground as the airmass is very dry below 10kft but will
start saturating the atmosphere aloft. Setup for early Saturday
morning through the afternoon still remains in flux. In general a
parent low will track across Ontario with a cold front draped
southwest through the Midwest. A secondary surface low will develop
along the southern extension of the front and track somewhere south
of the state line Saturday afternoon. Warm front will lift north
into SE MI early in the day with elevated showers beginning to
spread across the area during the predawn hours. The cold front will
lag behind passing in the early afternoon. Shear will be decent
early in the day with the low level jet off to the west, but will
settle more around 30 knots when the convection will likely reach SE
MI in the afternoon. Soundings are largely advertising CAPE in the
500-1000 J/kg range although there is a sliver of higher CAPE across
the Detroit area as it will have a little longer to destabilize in
the diurnal cycle. Overall not too impressed with instability though
as soundings show tall skinny CAPE with weak lapse rates owning to
the very moist environment once again with PWATs over 2 inches. This
is also dependent on amount of cloud cover and coverage of morning
showers. So overall, chances of rain early with chances of strong to
severe thunderstorms around 15-21Z with the cold frontal passage.

Another big surface high and upper level ridging settles across the
region later in the weekend and will carry through Monday night.
We`ll then have another trough start encroaching the area midweek
with the ridge trying to hold it off. So expectations are for a warm
up through the midweek with developing southwesterly flow and
chances of thunderstorms once the cold front gets pushed through.

&&

.MARINE...

High pressure in control today bringing moderate northerly flow to
the eastern Great Lakes. High pressure center moves overhead
overnight tonight which flips flow to become southerly tomorrow.
Winds strengthen to 15-20 knots and gust to 20-25 knots due to a
tighter pressure gradient moving in ahead of the next low pressure
center. Fresh winds remain in place as the low pressure center moves
in on Saturday and brings chances for showers and storms. Winds veer
to the northwest behind a cold front Saturday evening, but wind
speeds up to 20 knots will persist through the weekend.

&&

.PREV DISCUSSION...
Issued at 108 PM EDT Thu Jun 27 2024

AVIATION...

Strong static stability between 5.0 and 10.0 kft agl will ensure VFR
conditions throughout the period. Surface high pressure will pass
through through the region north winds to veer southeasterly with
time. Fair weather cumulus development will be possible at the base
of the inversion Friday with moisture advection holding off until
Friday night.

For DTW/D21 Convection... No thunderstorms today through Friday.

DTW THRESHOLD PROBABILITIES...

* Moderate for ceiling 5000 ft or this afternoon and Friday midday.


&&

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

$$

DISCUSSION...DRK
MARINE.......BC
AVIATION.....CB


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