947
FXUS63 KDTX 260655
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
255 AM EDT Wed Jun 26 2024

.KEY MESSAGES...

- Scattered showers and a few strong thunderstorms around today,
  especially south of M-59.

- Cooler and less humid air moves back into the area tonight and
  lasts through early Friday.

- Showers and strong thunderstorms return Friday night into Saturday.

&&

.DISCUSSION...

Strong upper level wave seen tracking through northern Minnesota
early this morning, and is expected to move through Lower Michigan
during the afternoon hours. Still some elevated surface dew pts
around over southeast Michigan this morning, mid 60s to around 70
degrees. However, the tight tight 850-700 MB theta-e gradient along
the southern Michigan border is sinking south, so our dew pts will
be mixing down during the day. None-the-less, with the
wave/shortwave trough approaching, some modest cold advection in the
mid levels (heart of the cold pool moves through northern Lake
Huron), at least high scattered showers appear in the offing as
surface troughing persists over southeast Michigan through the day.
MLcapes on the order of 1000+ J/kg will support isolated-low
scattered coverage of thunderstorms as well, and if dew pts do not
mix down during the day, MLcapes nearing 1500 J/kg would draw concern
for severe storms as 0-6 KM bulk shear ramps up (exceeding 50
knots). The issue is the blossoming showers/convection over southern
Wisconsin will likely be tracking through far southern areas during
the late morning hours/early afternoon hours, complicating the
forecast/instability as well. NAM soundings are a bit of an outlier
late this afternoon, and will lean toward the more subdued/less cape
solutions of RAP/HRRR/ARW/Canadian. Even so, the storms around noon
will be strong and may approach marginal severe limits with the
initial steep mid level lapse rates present, south of M-59.

Upper level northwest confluent flow will allow sprawling high
pressure to build into the Central Great Lakes tonight through
tomorrow, and into the eastern Great Lakes Friday morning. Return
flow around the high will ramp up through the day on Friday, with a
strong and active warm front lifting through the Midwest. With the
warm front arriving Friday night and the strong moisture advection
(pw values of 2 inches feeding in), showers and thunderstorms are
likely. Another amplified upper level trough/wave for summer
standards swings through the Western Great Lakes on Saturday. Amount
of destabilization in between the warm and cold front and position
of the triple point will determine our severe chances, as a high
degrees of 0-6 KM bulk shear arrives by early Saturday evening.

&&

.MARINE...

Upper level troughing has settled over the Great Lakes with surface
high pressure over the upper Midwest gradually building into the
central Great Lakes by late this evening. Before this occurs, a
lingering weak frontal boundary over southern lower MI offers the
potential for scattered showers and thunderstorms to develop during
the daylight hours, mainly over waters south of Port Austin. Cooler
northerly flow persists today and Thursday behind said front before
flipping back to southerly Friday as the high center shifts east of
the area. Winds during timeframe generally hold at or below 20kts.
Unsettled weather arrives late Friday into the weekend as low
pressure tracks into the upper Midwest.

&&

.PREV DISCUSSION...
Issued at 1147 PM EDT Tue Jun 25 2024

AVIATION...

Some pockets of lower stratus will exist across the Detroit corridor
early this morning as low level moisture quality improvies, but with
observational evidence suggesting coverage remains at scatterd. A
brief broken coverage remains possible through this corridor,
featuring a lower VFR/marginal MVFR ceiling. This moisture may offer
a window for shallow fog formation during the early morning hours,
although confidence in occurrence remains quite low owing to
substantial high cloud and existing low level southwest gradient. A
moist and weakly unstable environment brings potential for shower
and thunderstorm development during the daylight period Wednesday.
Greater potential with southward extent, highlighted by a main
window from PTK southward for some convective showers and a lower
probability mention of tsra. Prevailing southwest winds lasting
throughout the day, shifting to northwest a frontal boundary sags
through the region late afternoon into the evening.

For DTW/D21 Convection...Low probability for thunderstorms will
exist from late morning into the afternoon on Wednesday.

DTW THRESHOLD PROBABILITIES...

* Low for ceilings aob 5kft overnight and Wednesday.

* Low for thunderstorms Wednesday.


&&

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

$$

DISCUSSION...SF
MARINE.......KDK
AVIATION.....MR


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at www.weather.gov/detroit.