543
FXUS63 KDTX 191043
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
643 AM EDT Sat Apr 19 2025

.KEY MESSAGES...

- Widely scattered pockets of showers and thunderstorms cross the
area early this morning ahead of a slow moving cold front. Could see
a few showers linger near the Ohio border into this afternoon before
the cold front fully vacates south.

- High pressure builds in behind the front today ushering in drier
but cooler weather for the weekend. Coolest day Thursday with highs
in the 50s though lakeshore areas, especially the eastern Thumb,
struggle to get out of the 40s.

- Next low arrives Monday bringing additional shower and
thunderstorm chances. Windy conditions with gusts in excess of 35mph
looking increasingly likely late day Monday.

&&

.AVIATION...

Cold front clear the area this morning. Moist low level environment
arrives within the immediate wake of this boundary, lending to a
high coverage of MVFR to low VFR stratus today. Clearing potential
unlikely until late in the day or into the evening as drying
conditions increase. Some intervals of gustiness from a prevailing
westerly wind today. Veering winds tonight as lingering high cloud
thins with time under building high pressure. This affords a period
of clear sky heading into Sunday.

.DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 ft or less until Saturday afternoon.

&&

.PREV DISCUSSION...
Issued at 328 AM EDT Sat Apr 19 2025

DISCUSSION...

Slow moving cold front is now just starting to reach the Saginaw
Valley at time of discussion. Scattered pockets of elevated
convection in advance of the front are struggling to maintain
themselves as they reach this side of the state owing to unfavorable
timing with the diurnal minima in instability (MLCAPE only around
500J/kg). Only severe hazard with this convection would be hail,
given their elevated nature, however with the limited CAPE and mid-
level rates falling to around 6 C/km, this potential is near nil.
Locally heavy rainfall is possible under any convection as the
19.00Z KDTX RAOB observed 1.40" of PW (the daily climatological max
was of 1.32") with a modestly deep warm cloud layer of 7-8kft. That
said, with storm motions between 50-60mph, short residence times
over single locations is expected keep QPF in check. Cold front
eventually clears the bulk of SE MI by mid-late morning as surface
high pressure over the northern Great Lakes fills in behind it.
Could see some (thunder)showers linger near the Ohio border,
potentially as far north as I-94, through the first half of the
afternoon as the cold front briefly stalls out over northern Ohio.

Surface high becomes fully established over the state by this
evening ushering in drier, but cooler conditions as 850mb temps fall
to around 0C. Increasing subsidence and a drier inbound airmass
scour out low level moisture leading to a north to south clearing
trend late this evening through the first half of tonight. This in
combination with weak surface winds under the high support efficient
radiational cooling dropping lows in the lower to mid 30s for areas
along/north of M-59. Later clearing timing for areas to the south
keep temps a bit warmer in the upper 30s to around 40 for Detroit.
Sunday likewise will be below average as the ridge axis is slow to
cross the state maintaining thermal troughing and surface E/ENE flow
off the lakes. Inland areas look to top out in the mid to upper 50s,
aided by sun first half of the day before arrival of high cloud.
Lakeshore areas however struggle to get into the lower 50s with the
eastern Thumb in particular likely staying in the 40s.

Potent southern stream mid-upper trough is drawn north out of the
southern Plains into the Midwest Sunday as it phases with a weaker
northern stream shortwave. Prior cold front over Ohio is lifted back
north as a warm front in response with the elevated portion reaching
SE MI by Sunday evening. Only a slight chance (15-20%) to see any
showers along this part of the frontal slope as the trough
positioning over the Midwest results in induced mid-level ridging
from the eastern Great Lakes into SE MI. Best shot to see rain would
be towards central MI as this area resides on the fringe of height
rises. Occluding surface low pressure then arrives over the western
Great Lakes early Monday, tracking towards the Soo over the course
of the day. Widespread showers and a few embedded thunderstorms
likely Monday morning as the surface warm front attempts to lift
into the region. While mid-range model solutions are favoring this
front being able to push at least partially into the area, they have
trended more aggressive on the cold/occluded front sweeping in by
afternoon-early evening. The race between how far north the warm
front reaches before the cold front arrives will determine how warm
areas actually reach (ie reaching lower 70s vs staying lower 60s) as
well as how long rain lingers into Monday afternoon-evening as dry
slotting wraps in behind the occluded front. For now tried to play a
middle ground and lowered NBM temps down towards the mid-upper 60s
as well as trimming back PoPs to lower end chance (15-35%) for
Monday evening. Mixing depths increase to around 4kft (5kft in more
aggressive solutions) latter half of Monday with low level lapse
rates rising above 7 C/km as cold advection develops behind the
cold/occluded front. This would be more than sufficient to mix down
40-45kt flow aloft and support windier conditions with gusts
reaching 35mph, if not approaching 40mph, before weakening overnight
with the loss of solar insolation/diurnal mixing.

MARINE...

Frontal zone is slowly progressing across lower Michigan this
morning, and will eventually settle southeast of the forecast area
by mid-morning. Lingering convection will come to an end with the
departure of this front. Benign conditions prevail for the remainder
of the weekend for most of the waterways, although the NW-SE fetch
of northern Lake Huron will create a corridor of enhanced winds and
waves during the day. The next low pressure system arrives early
next week, tracking along Lake Michigan toward the Straits. This
will send an occluding front through the area Monday, introducing
the next chance for widespread rain and active marine weather.

&&

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

$$

AVIATION.....MR
DISCUSSION...KDK
MARINE.......MV


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