Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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FXUS63 KDTX 230357
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1157 PM EDT Fri Mar 22 2024

.KEY MESSAGES...

- Dry weather with below average temperatures this weekend.

- Warmer temperatures and rain showers return for early next week.

&&

.AVIATION...

The evening band of snow across SE Mi has exited eastward with low
pressure tracking through the upper Ohio valley. The system leaves
behind borderline MVFR/VFR clouds that extend into Upper Mi and
WI/IL. Nearly due north cloud layer wind does favor some breaks in
coverage late tonight, especially in the MBS to FNT area. Model
soundings then indicate an IFR fog component is possible where any
larger clearing can occur for a longer time period around sunrise.
Open sky fills back in quickly during the morning as boundary layer
instability builds, however these clouds are projected to reach low
end VFR through the afternoon into Saturday evening.

For DTW... As snow comes to an end, clouds left behind are
borderline MVFR/VFR below 5000 ft late tonight. Ceiling becomes more
consistently VFR toward afternoon with some breaks in coverage
possible Saturday evening.

.DTW THRESHOLD PROBABILITIES...

* High for ceiling 5000 feet or less late tonight through the day.

&&

.PREV DISCUSSION...
Issued at 356 PM EDT Fri Mar 22 2024

DISCUSSION...

The Winter Weather Advisory Advisory for the M-59 corridor and
counties north remains in place into tonight. Areas along and north
of the I-94 corridor across Wayne and Washtenaw county saw repeated
rounds of moderate to heavy snowfall leading to a couple reports of
over 4 inches. This southern edge of precipitation has lifted north
of these counties and thus the Advisory was allowed to expire at
18Z.

The main mid-level shortwave continues to track east across the
Great Lakes and has brought the expected SW to NE orientation of the
snowfall axis that is focused generally along and north of the I-69
corridor. There has been a general lull in the more widespread
moderate snowfall, but some isolated mesoscale snow bands and
cellular structures in the M-59 to I-69 corridors offered periods of
more intense areas of snowfall earlier this afternoon. Here at press
time, steady snowfall continues across the I-69 to M-46 corridors
and the shallow dry slot around 800-900 mb has brought dry
conditions along and south of M-59 with temperatures that have
climbed into the mid/upper 30s across far southern portions of the
CWA.

Guidance continues to point towards a secondary period of moderate
to heavy snowfall later this afternoon into this evening as right
entrance region jet dynamics aide in a strong FGEN response. This is
starting to show itself to our west. The bulk of Midland and Bay
County look to be just north of this more focused area of moderate
to heavy snowfall with models pointing toward the M-46 corridor to
the I-69 corridor being the more favored area of snowfall rates that
may reach or exceed 0.5-1.00" per hour at times. However, a boost in
snowfall may occur across these counties as flow pivots more
northeasterly and lake enhance showers may emerge off Saginaw Bay.
Will keep the advisory going in Midland and Bay for this possible
outcome. For the Saginaw to Flint corridor, peak snowfall will fall
between now and roughly 7-8pm. As the main wave works through the
northern Great Lakes, the associated cold front will start pushing
south and drive the main snow axis southeast as well. The puts a
secondary peak for areas south of I-69 in the 7 pm to midnight time
window. An additional 1 to 4 inches of snowfall can be expected for
these areas with the potential for localized higher amounts under
any focused heavy snow bands.

There has been some general agreement a general weakening within the
snowfall axis this evening as it starts to work southward toward the
Detroit Metro region. This occurs as overall lift and focus FGEN
weakens with the loss of better jet dynamics. However, the potential
for an isolated vigorous band or two to develop remains possible.
The main snowfall axis move southeast of the CWA by 06Z. A few light
snow showers will be possible, mainly across the Thumb, as cold
advection works through the state in the wake of the cold front.
High pressure then builds into the region with below normal
temperatures holding throughout the weekend as high temperatures
hold mostly in the 30s. Pattern change expected early next week as
warmer temperatures arrive along with rainfall and possible
thunderstorms early to middle of next week.

MARINE...

Widespread snow continues across northern Lake St Clair and Lake
Huron as an elevated warm front pivots overhead. Fluctuations in
visibility to a mile or less are possible within heavier bursts of
snow that are embedded in a larger area of WSW-ENE banding. The
ongoing band will shift back to the south as high pressure
aggressively fills in from Canada for Saturday, bringing an end to
the snow late tonight and shifting wind direction to the north. Did
decide to cancel existing Small Craft Advisories with this issuance
as waves have dropped below 4 feet. Another round of advisories will
be needed for most of the Lake Huron shoreline for Saturday as waves
ramp back up, but will defer issuance to the evening update for
clarity. Otherwise high pressure dominates the forecast this weekend
ahead of the next low pressure system brings rain and stronger winds
to the Great Lakes early next week. Will be watching for gale
potential with this system.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.

Lake Huron...Small Craft Advisory from 10 AM Saturday to midnight EDT Saturday
     night for LHZ421-441>443.

Lake St Clair...None.

Michigan waters of Lake Erie...None.

&&

$$

AVIATION.....BT
DISCUSSION...AA
MARINE.......MV


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