502
FXUS63 KDTX 120413
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1213 AM EDT Sat Jul 12 2025

.KEY MESSAGES...

- Increasing potential for showers and thunderstorms today which
  could produce isolated severe storms and localized heavy rainfall.

- Warmer summertime pattern underway which will continue into next
  week today, continuing through midweek as humidity rises and heat
  indices hover around 90.

- Drier weather expected Sunday through midweek as high pressure
  moves over the area.

&&

.AVIATION...

VFR skies should hold through the early morning period with
southeast Michigan in the warm sector and high clouds streaming in
downstream of a large convective line. Winds hold out of the south
and stay below 10 knots. Increasing southwest flow with gusts to
around 20 knots are expected by the afternoon ahead of an advancing
cold front. This front is expected to trigger increasing coverage of
showers and strong to severe thunderstorms, possibly by the early
afternoon hours.

For DTW/D21 Convection... There will be an advancing cold front that
will trigger a chance for strong to severe thunderstorms this
afternoon. Initiation looks occur around 17-18Z. Current timing for
activity to reach DTW looks closer to around 19-20Z. Adjustments in
timing remain possible.

THRESHOLD PROBABILITIES...

* Low for ceiling 5000 ft or less outside of thunderstorms today.

* Medium for thunderstorms this afternoon.

&&

.PREV DISCUSSION...
Issued at 346 PM EDT Fri Jul 11 2025

DISCUSSION...

Remnants of last nights elevated MCV still working through SE MI
this afternoon with a bit of an uptick in convection as the surface
warm front lifts up through the region. There is still a chance to
build some instability once this moves through this evening but
chances decrease as subsidence in the wake of the MCV should help
minimize coverage of new development. We`ll keep the current chance
pop going as the clearing upstream is already allowing a bubble of
SBCAPE in excess of 2000 J/kg to build and the nose of the 850mb low
level starts pushing into SW lower. Shear will remain fairly weak,
around 20 knots, so storms should struggle to get too organized but
an isolated storm or two may become strong to severe. Damaging
downbursts winds would be the biggest threat with heavy downpours
also a concern as dewpoints are rising into the 70s behind the
lifting warm front and PWATs are up around 1.75 inches. We remain in
a Marginal Risk for severe weather today.

Better chance for strong to severe storms comes Saturday as a
northern stream trough moves into the Midwest and pulls the stalled
shortwave over IA rapidly northeastward tonight through the northern
Great Lakes with the trailing cold front draped just west of Lake
MI. This puts us solidly in the warm sector tonight into Saturday
with southwesterly flow through that time. There will be a chance of
isolated showers/storms tonight with highest chance up across Mid MI
with a leading edge of the theta e gradient. Rest of SE MI should be
fairly quiet.

On Saturday there is a Slight Risk of severe weather per SPCDY2. The
main trough axis approaches toward morning with the increasing low
level jet pushing a weak shortwave up through SW MI which in turn
pulls up a secondary warm front/theta e surge. Strong WAA will bring
temps to near 90 with dewpoints into the 70s ahead of the cold front
which looks to sweep through the area during peak heating in the
evening. Most CAMs suggest initiation around 18Z with the frontal
line of convection pushing through by about 00Z. SBCAPE will rise to
around 2500 J/kg with shear remaining on the lower side around 25
knots but could reach up to around 30, sufficient to help storms
organize. Wind still looks to be the main threat with these storms,
with hail and heavy rain additional threats. Still cannot rule out a
tornadic threat with the warm fronts in the area.

Quieter weather to end the weekend Sunday as mid level trough lies
over the region and high pressure starts building in. Cold front
could get hung up over far eastern lower MI which could spark a few
showers Sunday, but most of SE MI will remain dry. Nearly zonal flow
with a slight broad mid level ridge builds over the region to start
the week with the next chance of storms targeting the area on
Wednesday as the next trough arrives.

MARINE...

A weak area of high pressure will continue to promote lighter winds
through the remainder of the day. Scattered to numerous showers with
some embedded thunderstorms remain possible through the afternoon
and evening, which brings the chance to see some embedded stronger
wind gusts. Additional chances for showers and thunderstorms will re-
enter Saturday into Sunday ahead of and along a cold front, which
brings additional chances for strong to severe thunderstorm
development capable of producing wind gusts aoa 35 knots. Winds veer
from southeast to southwest through tonight into tomorrow, with
continued veering to the west after the passage of the front. Dry
conditions return in the wake of the front.

&&

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

$$

AVIATION.....AA
DISCUSSION...DRK
MARINE.......AM


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