568
FXUS63 KDTX 230813
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
313 AM EST Sun Feb 23 2025

.KEY MESSAGES...

- Mild temperatures are expected through the first half of the week.

- Windy conditions, with gusts over 30 MPH, are expected Monday.

- Rain is likely on Wednesday, with some snow possible across the
Saginaw Valley and thumb.

&&

.DISCUSSION...

Inbound mid/high level clouds are associated with a low amplitude
mid level short wave tracking from the Dakotas into Minnesota. This
wave will traverse Lower Mi late this afternoon and evening. Weak
system relative ascent in the mid levels, relatively high static
stability aloft and ample low level dry air will significantly limit
snowfall potential with this system. Model soundings generally
suggest a little better moisture quality across the Saginaw Valley
and thumb region where ascent will be a little stronger and through
a little deeper layer. This will support just a low chance for light
snow and/or flurries in this region, with just clouds farther south.
Light south winds will drive slightly warmer low level air into Se
Mi today (925mb temps around -3 to -4C). The warming will be offset
by the increasing clouds, keeping max temps in the 30s.

A mid level short wave ridge will expand across Se Mi tonight. There
will be a rapid increase in the low level southwest winds across the
western Ohio Valley and southern Great Lakes tonight (925mb winds to
40-45 knots by 12Z Monday). The will support aggressive low level
warm air advection overnight into Monday morning as 925mb temps push
+7C. The gradient flow will limit the depth of the nocturnal stable
layer, suggesting nighttime mins will hold steady in the low 30s if
not gradually rise overnight. A northern stream short wave is
forecast to advance across the northern lakes on Monday. This will
drive a cold front south into Lower Mi and will suppress the core of
the warmer low level air to the south. Diurnal mixing into the
strong winds aloft will support breezy conditions on Monday, with
high probabilities for gusts over 30 MPH during the peak in the
diurnal heating cycle. Mixing will easily support highs into the
40s. A few locals in the south may be able to break 50.

Yet another short wave impulse is forecast to traverse the region
Monday night into Tuesday. The overall lack of moisture will limit
precip chances to just low chance Mon night. The bulk of model
guidance indicates some tightening of the low level baroclinic zone
across srn Lower Mi by Tues afternoon the wake of the short wave.
This will support a decent range in high temps across Se Mi, from
the 30s in the thumb to 40s across the south. There is respectable
agreement among the medium range model suite in showing a little
more amplified wave tracking across southern Lower Mi on Wednesday.
This wave will interact with the baroclinic zone across Lower Mi and
invoke a respectable FGEN response. Given this is still in the day 4
period, this is ample room for adjustment in later model runs. The
00Z ensemble members are suggesting the more robust FGEN response
occurring across the Saginaw Valley and Thumb region, with a more
convective rain component farther south. A big uncertainty at this
point is the thermal profile across the north, where the rain/snow
line will be in the vicinity. At this point, a chance of snow will
be mentioned across the far north, with high rain probabilities
across the rest of the forecast area.

&&

.MARINE...

Lighter southwest winds hold through daytime today as a combination
of a weaker gradient and continued warm advection keep surface winds
at or below 15kts. Winds do eventually begin to strengthen overnight
into Monday as strong low pressure tracks over far northern Ontario.
Increasing warm southerly flow over cold/ice covered lake waters are
not conducive for robust mixing, so despite 35-40kt flow at 1.5-2kft
agl, forecast winds are anticipated to generally hold below 30kts
across the central Great Lakes. Area of potential exception is the
Saginaw Bay/central Lake Huron given the favorable fetch, however
peak gusts over these waters look only to top out around 30kts. Low
pressure quickly moves into northern Quebec Monday night resulting
in a weakening local gradient and likewise weakening winds to at or
below 15kts. System`s associated cold front eventually sinks across
the region late night into Tuesday morning setting up NW flow
however no significant changes in wind strength occur due to the
detachment from the parent low.

&&

.PREV DISCUSSION...
Issued at 1158 PM EST Sat Feb 22 2025

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.


&&

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

$$

DISCUSSION...SC
MARINE.......KDK
AVIATION.....BT


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