277
FXUS63 KDTX 071959
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
359 PM EDT Mon Apr 7 2025

.KEY MESSAGES...

- Scattered snow showers through this afternoon with decreasing
  coverage into tonight focused across northern Thumb. Scattered
  light snow showers/flurries possible tomorrow afternoon.

- Winter-like wind chills this evening through Wednesday morning.
  Coldest wind chills down into the teens tonight.

- Likely precipitation Wednesday night and Thursday with a chance
  for rain and snow.

&&

.DISCUSSION...

Cold front is progressing east of Michigan this afternoon with post
frontal winds now out of northwest. These winds will be ushering in
a blast of arctic air to the region as the mid/upper trough swings
into the New England region. Temperatures at 850 mb will plummet
towards -15C by tomorrow morning supporting plenty of lake clouds
through the remainder of the day along with gusty winds. Winds
advertised within the mixed layer of 25-30 knots will support
afternoon and evening gusts mostly around 30-35 mph. Higher end of
the gust spectrum will be towards the northern Thumb. Boost in lapse
rates and just enough low level moisture supported by the lakes will
keep predominately scattered snow shower chances in the forecast
through the afternoon into the early evening.

Activity becomes focused over the lakes tonight with northern
portions of the Thumb holding chances for snow showers. Arctic air
results in cold overnight low temperatures down into the low 20s.
Gusty conditions ease throughout the night, but wind chills are
still forecast to be in the teens by tomorrow morning.

Surface high pressure drifts out of the western Great Lake states
and pivots through the Ohio Valley tomorrow and tomorrow night. Well
below average daytime highs tomorrow with the central Great Lakes
still under the influence of the thermal trough. Expect afternoon
highs mostly in the mid to upper 30s. Very dry airmass will be in
place with PWATs falling down below a quarter inch. However, have
introduced low POPs for snow showers/flurries into the forecast.
Lake moisture will be sustained within the northwest flow on the
back side of the mid level trough. Soundings indicating the cloud
layer will be supersaturated with respect to ice and within the DGZ
offering at least a low end chance for isolated/scattered lake
effect activity.

Upper level jet rounding the northern US Rockies down through the TN
Valley will trigger a surface low pressure within the left exit
region. There remains a fair amount of variability within the
solution space with this system as to how amplified the trough
becomes with the 12Z Euro still advertising a weaker open wave
solution and further south low track while GFS/NAM spin up the low
and lift it across OH and northeast across Lake Erie. In the later
scenario, any decent banding that can develop within the deformation
zone would bring the better accumulating snow potential. Soundings
of the northern three quarters of the CWA are cold enough for snow.
Would anticipate a fair degree of melting though, which require the
higher rates for any appreciable accumulation. Will ride with the
offered guidance of likely PoPs across the CWA and a chance of
rain/snow with limited snow accumulation. Adjustments will be needed
if the stronger wave over the southern Great Lakes pans out.

High pressure returns in the wake of this system on Friday with
temperatures still on the cooler side of average to close out the
work week. Warmer temperatures then expected for the weekend as
ridging builds into the region behind the departing trough. Daytime
high temperatures climb into the 50s and 60s over the weekend.

&&

.MARINE...

Low pressure (~1003 MB) tracking through Georgian Bay this
afternoon, with strong north-northwest winds ushering much colder
air (850 MB temps in the negative mid teens) into the Central Great
Lakes this evening/tonight, supporting freezing spray. Wind
observations this afternoon have been supportive of gale warning
wind gusts, and no adjustments will be made to the headlines. May be
able to take down the gale warnings a bit earlier than the end times
however. The pressure gradient slackens tonight to allow winds to
diminish as high pressure builds over the Western Great Lakes,
sliding east during Tuesday to promote light winds over the Central
Great Lakes Tuesday night into Wednesday.

Light to moderate southeast to northeast winds then develop with a
flat surface low tracking through the Ohio Valley Wednesday night-
Thursday bringing snow/wintry mix and rain to the Central Great
Lakes.

&&

.PREV DISCUSSION...
Issued at 126 PM EDT Mon Apr 7 2025

AVIATION...

A cold front continues tracking southeast across the metro area this
afternoon, marked by a band of light to moderate rain and snow.
Where precip rates are heavier, snow becomes dominant with brief
visibility drops to MVFR to IFR possible. No accumulations
anticipated. The post-frontal period offers NW gusts around 30 kt and
predominant MVFR ceilings as well as potential for additional widely
scattered snow showers. Ceilings are then favored to trend toward VFR
late this afternoon into tonight with some pockets of sub-5000 ft
ceilings possible at times. The boundary layer stays mixed,
maintaining a gust component to the NW wind tonight into Tuesday. A
weak disturbance will bring potential for additional ceilings and
snow showers during the day tomorrow.

For DTW... The cold front will bring the chance for rain/snow
showers through 20Z with no snow accumulation expected. Gusts to 25-
30 kt likely within the ensuing cold advection with direction mainly
from a 320 to 340 direction.

DTW THRESHOLD PROBABILITIES...

* High for ceiling at or below 5000 feet this afternoon. Low tonight.

* Moderate for rain/snow mix this afternoon. Low for snow showers
  Tuesday.

* Low for the crosswind threshold being exceeded this afternoon.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning until 10 PM EDT this evening for LHZ361.

     Gale Warning until 1 AM EDT Tuesday for LHZ362-363-462>464.

     Small Craft Advisory until noon EDT Tuesday for LHZ421-422-442-443.

     Gale Warning until midnight EDT tonight for LHZ441.

Lake St Clair...Small Craft Advisory until 4 AM EDT Tuesday for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 4 AM EDT Tuesday for LEZ444.

&&

$$

DISCUSSION...AA
MARINE.......SF
AVIATION.....TF


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