886
FXUS63 KDTX 230458
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1158 PM EST Sat Feb 22 2025

.KEY MESSAGES...

- Pockets of flurries possible Sunday afternoon near the Tri Cities
  and Thumb.

- Temperatures warm heading into early next week, with some
  regularity for highs at/above 40 degrees through much of the week,
  especially south of I-69.

- Mainly dry weather for the rest of this weekend with broader
  precipitation chances Monday night into Tuesday.

&&

.AVIATION...

Late evening radar composite indicates a plume of mid level moisture
out ahead of a cold front as it settles from northern Ontario into
the Straits area. Most of the radar detection is proving to be virga
except for a few snow showers reaching the ground toward APN and
later possibly grazing the Thumb. VFR above 5000 ft holds as rounds
of mid and high clouds continue late tonight and this afternoon.
Steady SW wind ahead of the cold front still requires Lake Michigan
be monitored for MVFR stratocu which has been slow to develop and
with less coverage during the evening. Predictability remains
marginal as persistent SW flow carries in gradually warmer air that
is also toward the dry end of the spectrum. VFR continues through
the day and a shallower boundary layer projected in model soundings
suggests there may not even be a gust component in the wind field in
the afternoon. A few pockets of light snow are possible toward MBS
by afternoon into Sunday evening.

.DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 359 PM EST Sat Feb 22 2025

DISCUSSION...

Afternoon GOES imagery shows a mix of mid- and upper-level clouds
triggered by a low amplitude shortwave trough tracking southeast
over the Great Lakes region. 22.12Z KDTX RAOB revealed an
approximately 10 kft deep layer of subsaturated air, roughly between
1.2 and 12.2 kft AGL. This helps limit precipitation production to
mainly sublimating snow, moreso across The Thumb. In the absence of
meaningful moisture advection, current KDTX/CASET radar trends still
show appreciable reflectivity returns (+10 dBZ) aloft which might
verify as snowfall (Trace) during the next few hours for Huron and
Sanilac Counties. Included flurry wording in the latest forecast
update. Gusty southwest winds should decrease off their diurnal
peaks (25-30 mph) late this evening as 35-40 knot LLJ winds exit and
the mixed-layer eventually collapses.

Geopotential heights reverse course, and begin to rise overnight,
behind the departing wave. Residence time of the short wavelength
ridge aloft will be brief, but should work to reduce cloud
fractions, albeit temporarily. Having some semblance of a
radiational cooling window lends additional confidence in one final
night of lows in the upper teens to lower 20s this month. A warming
trend commences Sunday and likely continues into next week.

Mainly dry conditions expected Sunday as the central Ontario surface
low eventually tracks into western Quebec while high pressure
influence extending north from the Tennessee Valley works to
maintain column stability, locally. A quick moving trough embedded
within the anticyclonic shear side of a synoptic ridge encompassing
western CONUS affords another opportunity for some low-confidence
flurries. Ensemble perspectives suggest difficulty producing
measurable precipitation again Sunday afternoon/evening, outside of
maybe some light snow for The Thumb region. Did add mention of
flurries. A degree or two warmer for highs Sunday (low to mid 30s),
but the bigger difference comes Sunday night into Monday as a warm
front starts to lift in, keeping overnight lows in the 20s.

850 mb temperatures climb into the low-mid single digits (Celsius)
which translates to highs near 40F to the lower 40s. Not much to
note in terms of ThetaE advection for Lower Michigan as another
surface low tracks east across Ontario, keeping most precipitation
well to the north. Can`t rule out some sprinkles or melting
snowflakes over The Thumb. Another wave ejects into the Ohio Valley
Monday night into Tuesday, but timing differences are still evident
in the deterministic data. A plume of moisture preceding this wave
appears sufficient for more favorable saturation profiles per PWATs
in excess of 0.50 inches. Expect some measurable rainfall with this.
Regularity for highs at/above 40 degrees noted through much of the
week, especially south of I-69.

MARINE...

Moderate southwest winds persist through the evening as a low-level
jet continues to slides across the central Great Lakes. Gusts
expected to hold at or below 30kts as warmer accompanying air
increases stability over the cold lake waters. Jet pushes east of
the region overnight resulting in a gradual but steady relaxation of
winds to below 15kts by Sunday morning. A more diffuse gradient,
thanks to the departure of James Bay low pressure, and continuing
warm air advection should keep winds on the lighter side daytime
Sunday- at or below 15kts. Southwest winds then increase late Sunday
night into Monday ahead of a strong low tracing over far northern
Ontario. This system strengthens the magnitude of warm air advected
into the central Great Lakes maintaining, if not increasing,
overlake thermal stability. As such, forecast currently is for gusts
to remain generally under 30kts despite the stronger winds aloft.
This system eventually drags a cold front across the region late
Monday-early Tuesday though with low pressure rapidly moving into
northern Quebec, SW turning NW winds weaken with the frontal passage.

&&

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

$$

AVIATION.....BT
DISCUSSION...KGK
MARINE.......KDK


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