534
FXUS63 KDTX 200956
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
556 AM EDT Sun Apr 20 2025

.KEY MESSAGES...

- Dry with cooler conditions today.

- Showers become likely tonight into early Monday. A slight chance
  of thunderstorms during this time.

- Turning windy Monday afternoon and evening with southwest gusts in
  excess of 35 mph.

&&

.AVIATION...

Surface high pressure in place today maintains VFR skies with cloud
cover largely confined to high cirrus. Mid-cloud between 7-10kft
builds in late afternoon-evening as the high departs in response to
low pressure lifting towards the western Great Lakes. A light shower
or two possible from these clouds as an elevated warm front lifts in
however overall chances and potential coverage are too low to
highlight in current forecast. Better shower chances arrive Monday
morning as the surface warm front arrives. A few embedded
thunderstorms possible within this activity however confidence is
not high enough to mention in TAF. Ceilings lower through the
morning as moisture increases with breezier conditions developing
(gusts increasing towards 30kts by late morning) as the low reaches
western Lake Michigan.

.DTW THRESHOLD PROBABILITIES...

* Low for ceiling at or below 5000 feet through this evening/early
  tonight, increasing to high by Monday morning.

&&

.PREV DISCUSSION...
Issued at 349 AM EDT Sun Apr 20 2025

DISCUSSION...

Deep layer stability held within existing low-mid level ridging
offers benign weather conditions today. Limited moisture quality
throughout the column lends to a high degree of insolation potential
overall, but with the likelihood for some increase in high based
cloud with time from south to north as mid level flow emerges from
the southwest. Veering low level flow from northeast to east
maintains a neutral pattern for thermal advection, so any airmass
modification generally reliant on the underlying increase in mean
thickness readings as upper heights build combined with at least
partial sunshine. This lands afternoon temperatures on the
cooler side of average, generally low to mid 50s.

Dynamic mid level wave set to eject from the southern plains to the
upper midwest over the next 24 hours. Inherent strengthening of
southwest flow along the east flank of the impinging height falls
will establish a corridor of greater moisture transport within a
blossoming region of warm air advection. Initial period of mid level
isentropic ascent arrives locally early tonight, affording some
pockets of high based light shower production but with dry easterly
low level flow mitigating a greater response. Main window for
convective shower production centered 09z-15z Monday morning as a
more focused region of forced ascent along the warm frontal boundary
anchors a peak in moisture quality and corresponding elevated
instability. Collective of ensemble guidance maintains a high
probability of precipitation this period, with instability worthy of
an isolated t-storm mention.

Cold/occluding front then sweeps through 14z-18z Monday. Warm sector
of this system will attempt to make brief inroads, at least across
the south, with the pace of the boundary governing duration and
magnitude of possible low level warming/moistening and corresponding
low level destabilization during this time. Modest destabilization
plausible (MLCAPE less than 1000 j/kg) as temperatures peak upper
60s/near 70F and dewpoints approach 60 degrees across eastern
sections of the area. This maintains at least a low likelihood for a
secondary response during the early afternoon hours, particularly
with eastward extent, before the opportunity shifts into Canada.
Ensuing late day cold air advection capitalizes on a firm southwest
gradient and improving mixing depth to generate windy conditions mid
afternoon in the evening hours. Solid gust potential within the 35
to 45 mph range during this time.

Lower amplitude mid level flow will dominate the mid week period.
High pressure in control ensures dry conditions with seasonable
temperatures Tuesday. Potentially more unsettled Tuesday night and
Wednesday as transient shortwave energy invokes pockets of
meaningful ascent at times across the great lakes. Forecast will
continue to highlight lower end rain chances at this stage. A
general moderating thermal profile with time will translate into
above average temperatures both Wednesday and Thursday.

MARINE...

Surface high pressure builds as it migrates across the Great Lakes
today. Winds respond to the movement of the high by veering from
northwest to easterly, but remain light under the diffuse gradient.
Upstream, low pressure lifts toward the Upper Midwest tonight and to
the Straits on Monday. Not out of the question to see a stray shower
this evening as the elevated warm front lifts through, but the
broader chance for showers and elevated thunderstorms begins early
Monday morning. This will be in response to strong moisture
transport occurring ahead of the front, driven by a ~60 knot low
level jet. Stable conditions keep the strongest winds elevated,
although an uptick in sustained easterly flow to 20 knots and gusts
to 30 knots will likely necessitate Small Craft Advisories beginning
Monday morning. The occluded front associated with this system lifts
through Monday afternoon, initiating cold advection and deeper
boundary layer mixing. Gusts still look to stay below gale force on
a widespread basis, although local enhancements may occur over
Saginaw Bay due to warmer water temperatures and fetch. Once this
system departs, benign conditions return for Tuesday.

&&

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

$$

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


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