431
FXUS63 KDTX 230005
AFDDTX

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

.KEY MESSAGES...

- Pockets of flurries possible this evening and Sunday afternoon 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...

A cold front settles from northern Ontario into the Straits area
tonight while a broad area of high pressure holds over the SE
States. This maintains a steady SW wind across Lower Mi tonight
after gusts drop off this evening. Current mid and high level clouds
are sustained by a series of waves in the northern branch of the jet
stream tracking along the US/Canada border. The potential for MVFR
cloud coverage carries lower predictability depending on marginal
activation of Lake Michigan as persistent SW flow carries in
gradually warmer that is also toward the dry end of the spectrum. Low
end VFR observations upstream at press time will be monitored for a
convincing MVFR trend later updates. At least low end VFR continues
through Sunday with a shallower boundary layer leading to gusts
limited to 20 knots or less. A few flurries 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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