187
FXUS63 KDTX 261102
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
702 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.

&&

.AVIATION...

A weak cold front paused southward progress in central Lower MI
during the night allowing an area of IFR fog to form in the humid
air south of the front. The fog affected FNT and MBS before high
clouds thickened leading up to sunrise and now follows a standard
trend of visibility improvement during the morning, especially as SW
wind picks up slightly.

Southward progress of the front is further delayed today by a wave
of low pressure moving in from the Midwest. Clusters of light rain
showers moving in from IA/MN/WI are a tracer for the low pressure
system which appears strong enough to leverage the front for
additional coverage of activity this afternoon. A prevailing VFR
shower with a thunderstorm prob still looks good during the mid to
late afternoon instability peak which then fades by mid evening.

The cold front exits south into the Ohio valley this evening
followed by a cool northerly boundary layer wind tonight. Borderline
VFR/MVFR ceiling is likely for a few hours given a boost of moisture
from Lake Huron late tonight into Thursday morning.

For DTW/D21 Convection... Showers increase coverage over D21 as the
day progresses. An isolated thunderstorm is possible along the YIP-
DTW-DET corridor from mid afternoon into early evening. Storms bring
brief IFR restriction and gusty wind while passing through the
region.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms this afternoon and evening.

* Low for ceiling 5000 ft or less in thunderstorms, moderate late
  tonight after cold front passage.

&&

.PREV DISCUSSION...
Issued at 255 AM EDT Wed Jun 26 2024

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.

&&

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

$$

AVIATION.....BT
DISCUSSION...SF
MARINE.......KDK


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