224
FXUS63 KDTX 052249
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
649 PM EDT Wed Jun 5 2024

.KEY MESSAGES...

- Widespread showers and thunderstorms this afternoon, ending early
this evening. Some of these storms may be strong to marginally
severe.

- Localized rainfall totals of 1 to 2 inches are possible for areas
that see multiple storms this afternoon.

- Pattern shift for the latter half of the week brings below normal
temperatures  through at least the end of the week along with
periodic chances of rain.

&&

.AVIATION...

Lingering remnants of this afternoons convection will be exiting the
northern portions of metro Detroit within the next hour or two.
Although some lingering post frontal moisture may support scattered
to briefly broken clouds below 5000 feet this evening, dry air
advection in the wake of this evenings cold frontal passage will
support VFR conditions, with just high based clouds expected. A
deepening upper low across the northern Great Lakes on Thursday will
sustain a strong westerly gradient across the southern lakes. This
along with the growth of the daytime mixed layer will support gusty
winds during the afternoon, with peak gusts around 30 knots
possible.

For DTW/D21 Convection...Lingering showers across the northern
portions of the airspace will weaken and exit to the east within the
next hour or two. No additional thunderstorms are expected tonight.

 DTW THRESHOLD PROBABILITIES...

* Low in crosswind thresholds being exceeded Thursday afternoon.

&&

.PREV DISCUSSION...
Issued at 324 PM EDT Wed Jun 5 2024

DISCUSSION...

Showers and thunderstorms have blossomed this afternoon over
southeast Michigan, and are tracking through a touch faster than
most hires solutions. Surface dew pts mostly in the 68-70 degree
range with MLcapes 1000-1500 J/kg per SPC mesoscale analysis. Better
shear (~35 knots effective shear) attempting to catch up to continue
to support isolated marginally severe storms. Regardless, some
storms will be strong producing wet micro-burst winds of 50+ mph.

Pronounced mid level dry slot arrives early this evening, ending
shower/thunderstorm activity (23-2z), with 850 MB Theta-E dropping
close to 20 K. Mid level cold pool (-22 C at 500 MB) will be pushing
into northern lower Michigan by Thursday morning, and lapse rates
look to be quickly steepening up with a narrowing moisture plume
streaming in from the Midwest, generating some modest cape in the
mid levels. Expecting scattered showers/isolated thunderstorms as
showalter index reaches at or slightly below zero. Yet another mid
level dry slot moving through during the afternoon hours, making
activity difficult with limited coverage at best. Increased mixing
depths expected to product breezy conditions, with westerly wind
gusts aoa 30 mph.

850 MB temps progged to bottom out in the mid single numbers Friday
morning, but with the slow movement of the large 500 MB low exiting
the northern/eastern Great Lakes, still probably enough marginal
instability to produce isolated-scattered shower activity, especially
over the Thumb region.

Short lived confluent upper level flow/shortwave ridging for the first
half of the weekend, before yet another upper level wave/re-
enforcing cold shot arrives for the second half of the weekend. 850
MB temps forecasted to bottom our in the 3-5 C range Monday morning.
Another upper level ridge, a bit more pronounced, is then expected to
build in for Tuesday, supporting temps slightly above normal.

MARINE...

The ongoing passage of a cold front will bring a line of showers and
thunderstorms across the Great Lakes through the afternoon and
evening. Some isolated development ahead of this main line is
possible. There will be a marginal risk for severe weather across
all of the eastern Great Lakes given the building instability, where
wind gusts in excess of 30 knots and hail to an inch will the most
likely hazards with the strongest storms. While much less likely, an
isolated waterspout cannot be ruled out with the thunderstorms.

Passage of the front will veer wind direction from the southeast to
the southwest. A cooler air mass will then gradually setup over the
Great Lakes into the end of the week. The enhanced mixing depths
will bring some breezy conditions, particularly for the nearshore
zones. A Small Craft Advisory has been issued for the Saginaw Bay
tomorrow as a smaller window for southwest fetch will enhance wind
gusts potential to around 25 knots, which would produce wave heights
to or in excess of three feet. Wind speed and gust potential will
then reduce in magnitude overnight.

HYDROLOGY...

Showers and thunderstorms around this afternoon will taper off early
this evening. The airmass is seasonably warm and moist. Thus storms
are efficient rain makers with widespread rainfall amounts up to
half inch expected. Localized higher amounts are possible in the
stronger thunderstorms, with potential storm total rainfall amounts
in the 1 to 2 inch range. Minor flooding of prone urban and low-lying
areas, ponding of water on roadways, and rises in area rivers will
all be possible.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 10 AM to 10 PM EDT Thursday for LHZ421-
     422.

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

$$

AVIATION.....SC
DISCUSSION...SF
MARINE.......AM
HYDROLOGY....SF


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