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000
FXUS63 KDTX 120355
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1155 PM EDT Thu Apr 11 2024

.KEY MESSAGES...

- A Wind Advisory is in effect from 8 AM Friday to midnight Friday
night. Northwest wind gusts peak at 45-50 mph with localized 55 mph
gusts possible Friday afternoon.

- Widespread rain continues tonight into Friday morning. Additional
rainfall around 0.5 inch is expected toward metro Detroit up to an
additional inch toward the Tri Cities and northern Thumb for storm
totals of 1 to 2 inches.

- There is a chance of elevated thunderstorms this evening. If
thunderstorms develop, they will be capable of producing locally
heavy rain and minor wind gusts.

- Wind diminishes Friday night leading to a new warming trend this
weekend. High temperatures are projected around 70 by Sunday.

&&

.AVIATION...

Midlevel frontogenesis underneath favorable, coupled entrance region
jet dynamics is leading to several north to south bands of showers
across Southeast Michigan. Many areas have now improved into the
MVFR flight category with cigs at or just above 1.0 kft agl. Winds
have emerged out of the northwest at all sites this evening in
response to low pressure passing east of the terminals. Preference
is to carry prevailing showers throughout the night as fgen forcing
gives way to increasing midlevel deformation. Northwest winds will
steadily increase tonight with very windy conditions expected Friday
afternoon. Northwest wind gusts in excess of 40 knots will be
possible during the afternoon. The atmosphere is forecasted to dry
out considerably after 22Z Friday, although did continue a broken
ceiling at less than 5000 ft through the early evening, clearing
after.

For DTW... High confidence in westerly wind gusts reaching at least
into the 35-40 knot range tomorrow, especially in the afternoon
hours.

.DTW THRESHOLD PROBABILITIES...

* High for cigs at or below 5k ft into Friday.

* High for west-northwest wind gusts reaching cross wind thresholds
  Friday.

&&

.PREV DISCUSSION...
Issued at 1113 PM EDT Thu Apr 11 2024

UPDATE...

High-end coupled upper level jet dynamics currently over Lower
Michigan this evening has resulted in a strong 850mb frontal zone
bisecting the central cwa from north to south under very persistent
925-850mb frontogenesis. Local DTX radar has been observing a primary
band of moderate rain anchored directly on this boundary for the
better part of 5 hours. Limited instability has allowed for rainfall
rates to be manageable with the higher end hourly rates at/around
0.25 inch. Radar storm total rainfalls are now ranging 1 to 2 inches
for much of southern Oakland County southward into
Washtenaw/Wayne/Monroe counties. Model data suggests the greatest
fgen forcing to remain in its current alignment through 06Z, only
slowly pivoting/shifting northeastward toward the eastern Thumb. Most
recent radar trends show a main slug of shower activity now lifting
northward through the Detroit Metro area tracking toward this general
vicinity with a much less coverage to the south. So expectations are
for the moderate rates across the Metro area to wane after midnight.
The rain will not end completely as midlevel deformation forcing
will fill in across Southeast Michigan supporting numerous to
widespread coverage of light rain through the day Friday.

PREV DISCUSSION...
Issued at 357 PM EDT Thu Apr 11 2024

DISCUSSION...

Rain showers have been widespread across SE Mi this afternoon but
with manageable intensity and rainfall totals so far. Totals since
about midnight range from around 1 inch south of I-94 to less than
0.25 inch toward the Tri Cities and northern Thumb. This sets up
well for continued manageable impacts during the remaining evolution
of the low pressure system that places greater rainfall farther
north tonight and Friday morning.

The large and well organized low pressure system spanning the TN and
OH River valleys is in a rapid deepening phase late today and
tonight. This means there is still a window for rainfall
overachievement within the currently overhead deformation axis,
especially as it intersects with the negative tilting mid level
circulation from IN/OH. Model plan view and cross sections indicate
850-700 mb gradients steepening with elevated instability extending
up to about 400 mb. This is a favorable setup for continued "banded"
convective clusters within the leading larger scale deformation zone
while more typical elevated cellular convection occurs toward the
mid level circulation center. Progression of the mid level
circulation forces renewed coverage of showers with a rumble of
thunder possible toward metro Detroit while banded coverage is
maintained toward the Tri Cities and northern Thumb this evening. The
NW flank of the mid level circulation gradually merges into the
larger scale deformation with a pivot point across the Tri Cities and
Thumb. This is where the higher end rainfall totals closer to 1 inch
are possible late tonight into Friday morning for a respectable 1 to
2 inch storm total footprint across the region.

Rain showers gradually diminish while Advisory worth wind ramps up
Friday morning. Powerful phasing of the current upper Midwest short
wave broadens the mid level trough by Friday morning which feeds
into nearly 15 mb of surface pressure deepening. The low level wind
field ramps up considerably as a result while combining with a
favorable environment for downward momentum transport. Model plan
view omega projections indicate large scale 850-500 mb subsidence
into a deepening boundary layer depicted well by model soundings.
Consensus of regional and hi-res deterministic runs widely advertise
50-60 kt 850 mb wind across Lower Mi as boundary layer lapse rate
builds through afternoon peak surface heating. The Wind Advisory
advertises high end 55 mph gusts, especially toward the Thumb, and
trends will be monitored for a potential short-fused Warning upgrade.

The Wind Advisory is in effect Friday and Friday evening followed by
a steady diminishing trend Friday night into Saturday. Dry and
warmer weather follows high pressure into the region for the
afternoon Saturday. An even stronger surge of warm air becomes
capable of nocturnal rain showers Saturday night and early Sunday.
The inbound warm air lifts temperatures back to around 70 Sunday
afternoon.

MARINE...

Deepening low pressure tracks up the Canadian Lake Huron shoreline
tonight resulting in a gradual shift in wind direction to
northwesterly by Friday morning as the low pushes into northern
Ontario. Low is expected to reach its minimum pressure during the
morning hours Friday resulting in a rapid strengthening of winds
across the central Great Lakes as colder air is pulled south into
the region. Overlake thermal profiles combined with a very tight
pressure gradient supports gales throughout all of Friday- strongest
flow over the northern two-thirds of Lake Huron where high-end gales
are likely throughout the afternoon into early Friday night. Can`t
rule out gusts reaching storm force over these waters particularly
during the evening hours. For now will continue to run with the Gale
Warning however the need for a shorter fused upgrade to a Storm
Warning will be monitored through the coming forecasts. For the rest
of the region, gusts between 35-45kts are favored.

Winds weaken through the day Saturday as the low slides into Quebec
allowing weak surface high pressure to gradually build into the
central lakes. A much weaker clipper system drops through the Great
Lakes Sunday bringing another round of showers as well as the chance
for a few thunderstorms over the southern Great Lakes. No wind
headlines expected with this system as gusts top out aob 25kts.

HYDROLOGY...

A widespread soaking rain is in progress across the Great Lakes as a
large low pressure system moves over the Ohio valley and into
eastern Canada. Rainfall totals today ranged from 0.25 inch north of
I-69 to around 1 inch south of I-94. Additional rainfall tonight is
expected to flip toward higher totals toward the Tri Cities and
northern Thumb and lower toward the Ohio border. There is a chance
for some localized heavy rain in thunderstorms this evening. The
forecast rain totals of 1 to 2 inches for the entire system will
lead to rises on area rivers and ponding on roadways. While
widespread flooding is not expected, minor flooding of prone urban
and poor drainage areas will be possible, especially if total
rainfall amounts end up being closer to two inches.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Wind Advisory from 8 AM Friday to midnight EDT Friday night for
     MIZ047>049-053>055-060>063-068>070-075-076-082-083.

Lake Huron...Gale Warning from 10 AM Friday to 10 AM EDT Saturday for LHZ422-442-
     443.

     Gale Warning from 6 AM Friday to 4 PM EDT Saturday for LHZ361>363.

     Small Craft Advisory until 6 AM EDT Friday for LHZ421-441.

     Gale Warning from 6 AM Friday to 10 AM EDT Saturday for LHZ421-441-
     462>464.

     Small Craft Advisory until 10 AM EDT Friday for LHZ422-442-443.

Lake St Clair...Small Craft Advisory until 10 AM EDT Friday for LCZ460.

     Gale Warning from 10 AM Friday to 10 AM EDT Saturday for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 10 AM EDT Friday for LEZ444.

     Gale Warning from 10 AM Friday to 4 AM EDT Saturday for LEZ444.

&&

$$

AVIATION.....CB
UPDATE.......CB
DISCUSSION...BT
MARINE.......KDK
HYDROLOGY....BT


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at www.weather.gov/detroit.