578
FXUS63 KDTX 170356
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1156 PM EDT Mon Jun 16 2025

.KEY MESSAGES...

- Hotter and muggier Tuesday into midweek.

- Showers and storm chances latter half of Tuesday. An isolated
damaging wind gust possible in the strongest storms.

- There is a Slight Chance for severe weather late Wednesday
afternoon into Wednesday night along with a Marginal Risk for
excessive rainfall for Wednesday and Wednesday night.

&&

.AVIATION...

Surface ridge axis with anticyclonic trajectory influence will
persist across Southeast Michigan tonight. There is some potential
for light br/hz at daybreak Tuesday. Surface trough and convergence
axis will approach southeast Michigan from the northwest Tuesday
afternoon. Surface wind directions are expected to veer to the south
southwest with notable midlevel thetae advection. The potential exist
for isolated to scattered thunderstorms Tuesday afternoon 21z-24z.
Low confidence exists in development and coverage and will limit
mention to PROB30 groups at the Detroit terminals.

For DTW/D21 Convection...Introduced a Prob30 group for thunderstorms
21-24z Tuesday. No severe weather expected.

THRESHOLD PROBABILITIES...

* There is a low chance for ceilings at or below 5000 feet Tuesday
  morning.

* There is a low chance for thunderstorms between 21z-00z Tuesday.

&&

.PREV DISCUSSION...
Issued at 338 PM EDT Mon Jun 16 2025

DISCUSSION...

Pleasant early summer day as high pressure centered over western
Lake Huron has kept skies mostly sunny for the bulk of SE MI which
helps to boost high temps toward the mid 80s by late afternoon. High
pressure gradually departs to the east overnight as a warm front
lifts through the region setting up southerly flow in its wake that
begins to advect the airmass residing over the Midwest into lower
MI. This keeps lows on the milder side as temps only bottom out in
the low to mid 60s as dewpoints gradually creep above the 60 mark.

Developing mid-upper troughing over the Plains induces strengthening
deep layer southwest flow locally Tuesday fully advecting the
Midwestern airmass into the central Great Lakes. 850mb temps reach
17-18C (up from 14C) allowing highs to reach well into the upper
80s. Surface Td`s climb into the upper 60s giving a muggier feel as
well as pushing both SB/MLCAPEs to between 800-1200 J/kg by
afternoon. Surface low pressure lifting out of Lake Superior into
northern Ontario drags a cold front into southern lower MI by late
Tuesday afternoon-evening which given the moisture/instability
already in place, should be more than sufficient to initiate a NE-SW
oriented broken line of convection over western/central MI. Given
the orientation, the Saginaw Valley could see storms by mid-
afternoon (~17-20Z) with this activity moving over the rest of the
area between ~20-01Z. Shear is not impressive within the warm sector
preceding the front as forecast soundings advertise a largely
unidirectional, well-mixed wind profile below 700mb yielding bulk
shear values at or below 25kts. That said, soundings also show an
inverted V profile that supports near 1000 J/kg of DCAPE and the
potential for downbursts under any of the more robust updrafts.
Frontal boundary still expected to stall out directly over southern
lower MI by late evening becoming the focal point for a couple more
chances of potential convection.

First of these chances comes Tuesday night from a potential remnant
MCS coming out of the IA/IL area. 12Z CAM guidance remain divided on
on both sufficient upscale growth to form this complex and its
track. While these solutions advertise similar magnitudes of
instability, they have significant differences in shear with bullish
solutions like the HRRR having a stronger wind and subsequent shear
profile to organize convection. Conversely solutions like the NSSL
have weak wind/shear profiles resulting in weak organization and
limited cold pool generation. Given south-southwest low level winds
feeding this convection, track would be favored to stay over
northern IL/IN. However a stronger outcome (like the HRRR) offers a
chance for the northern edge of this decaying line of convection to
reach SE MI as 400-700 J/kg of elevated instability will still be in
place for areas south of the stalled frontal slope. Overall
confidence is not high and chances aren`t particularly great given
the favored southerly drift in storms; however, with lingering
elevated instability and a frontal boundary in the area can`t rule
out at least some scattered showers/storms overnight so will
maintain lower end chance PoPs (~30%).

Better chances for storms arrive Wednesday as surface low pressure
rides along the front into lower MI late day. Stalled front is
partially lifted north as a warm front in response to the
approaching low allowing further moisture advection pushing
dewpoints toward 70- for areas south of I-69. PWAT`s likewise
increase above 1.5" and could cross the climo daily max for the day
of 1.7". Starting with the severe aspect, SPC has maintained a Day 3
Slight Risk over the central portions of the state with Marginal
Risk over the remainder of the area. These severe chances don`t
arrive until late evening/overnight with the arrival of the surface
low and its accompanying 50-60kt LLJ. Main concern on whether or not
severe storms can occur is the late arrival of the low as a sizable
subset of mid-range models are not showing it overhead until between
00-06Z, which reduces the amount of remaining diurnal instability
available (falls from 1500 toward 700J/kg over this timeframe) in
addition to greatly decreasing the likelihood for storms to remain
surface based the later it arrives. Another point of concern is that
there are chances for scattered showers and storms during the day
Wednesday along the front that could decrease the degree we
destabilize and limit overall max instability. Should the earlier
arrival solutions (ie evening) occur, damaging wind gusts would be
the primary hazard with a few tornadoes possible given the warm
front lifting over the area as the triple point tracks over or near
SE MI increasing low level curvature in hodographs.

In addition to the severe threat, the Gulf moisture feed pushing PW
values near daily records offers heavy rain/flooding potential with
storms Wednesday. Soundings also show warm cloud depths of 12-15kft
throughout the day increasing precip efficiency with any preceding
showers/storms along the front daytime Wednesday as well as
convection with the low itself late day. One additional point of
concern that will need to be watched in coming model cycles is some
signal amongst model solutions supporting training convection during
the day along the frontal boundary before the arrival of the low
which could boost overall QPF.

MARINE...

High pressure still influencing the region as it continues to drift
eastward today. The shift in position has resulted in a warmer
southerly flow over the waters with winds generally under 15 knots.
Slight increase in winds Tuesday behind a warm front lifting through
the area but still expected to be under 20 knots. The offshore flow
should also minimize any increased wave potential. An unsettled
pattern follows through the rest of the week as a series of low
pressure systems track through the region. Showers and thunderstorms
will be possible each day with potential for strong storms on
Wednesday.

&&

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

$$

AVIATION.....CB
DISCUSSION...KDK
MARINE.......DRK


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