National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KDTX 122353
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
753 PM EDT Fri Apr 12 2024

.KEY MESSAGES...

- A Wind Advisory is in effect from 8 AM this morning to midnight
tonight. Northwest wind gusts peak at 45-50 mph with localized 55
mph gusts possible early this evening in the Thumb.

- Widespread rain continues today with highest rainfall amounts
toward the Tri Cities and Thumb where up to an additional inch of
rainfall is possible. Elsewhere, additional rainfall amounts will be
a half inch or less.

- Wind diminishes overnight with a gradual warming trend through the
weekend into next week.

- Thunderstorms are possible Sunday as a weak low pressure system
and cold front track through the area.

&&

.AVIATION...

The strong cold conveyor with winds of 50-60 knots is currently
overhead of the cwa wrapping around the low pressure system near
Georgian Bay. Steep subcloud lapse rates into neutral to slightly
convectively unstable between 3.0 to 5.0 kft agl has led to periodic
gusts the past hour or so at 40 to 45 knots at FNT and MBS. Last bit
of deep 925-850mb thetae/moisture will advect through the northern
forecast area between 00-03Z this evening before substantial drying
pushes directly into Southeast Michigan. As the subsidence arrives,
warming low-midlevel will result in higher stability and lowering
winds. Strong geostrophic/gradient wind will continue winds of 20 to
30 knots tonight. Clearing is expected late tonight and Saturday.
West northwest winds Saturday of 20 to 30 knots.

.DTW THRESHOLD PROBABILITIES...

*  Moderate for cigs at or below 5k ft this evening.

&&

.PREV DISCUSSION...
Issued at 331 PM EDT Fri Apr 12 2024

DISCUSSION...

Rapid deepening of low pressure has commenced over the past 12-24
hours characterized by a 1000-500mb 12 hr height change down to 13
dam, where a now 977 mb low now sits over western Ontario. To put
this in perspective, a low of this strength for this time of year
falls outside all of climatology w.r.t the CFSR data. An
uncharacteristically strong low level jet has and will continue to
increase in intensity along the western flank of the departing low
pressure system through the remaining afternoon and evening hours.
With several hours of diurnal heating remaining, shallow mixing
depths will continue to tap into the llj, producing 45-50 mph wind
gusts. Isolated peak gusts to 55 mph cannot be ruled out across SE
MI, but this is more favorable across the Thumb and especially along
the shoreline given the peak jet maxima location resides across this
area. This location also has favorable isentropic downglide and west-
northwest flow off the bay/lake. Wind gust intensity will wind down
between 8PM-10PM EDT, where the wind advisory is then expected to
expire.

Rain showers will also recede from southwest to northeast through
the remainder of the day, fully exiting the Thumb between 10PM -
Midnight. Visible satellite has been interesting to observe through
the day which highlights the west-northwest surface to 600mb flow,
juxtaposed by the southeast to northwest upper-level flow from 400mb-
300mb. Vertical wind profiles highlight the elevated nature of this
frontal boundary through h300, which is one mechanism for the
ongoing precipitation, with additional support from the PV features
with the low, fed with a surge of wrap around moisture.

The loss of diurnal heating late tonight and overnight will produce
a shallow stable layer through 200 ft which will cut off the
stronger winds aloft, although the pressure gradient will still
support sustained winds of 15-20 mph through the mid-morning hours.
Gusts to 30-35 will also remain possible with any brief neutrality
to the stable layer. Otherwise, a PV filament will swiftly move over
MI between 06Z-12Z, and behind it, subsidence with a deep dry layer
ribbon. This will help support clearing trends by daybreak, with
stability further reinforced from surface to mid-level ridging. This
will set the stage for sunny skies tomorrow, albeit still breezy.
Diurnal heating will tap into a weaker wind field aloft, producing
gusts 25-30 mph, isolated up to 35 mph. Peak gusts will be favored
in the late morning to early afternoon, waning into the evening
hours.

Dry conditions will continue into early Sunday morning, with a
clipper low pressure system bringing the chance for elevated rain
showers focused over the Tri-Cities and Thumb. Thunderstorms also
remain a possibility with mid-level lapse rates near 7C/km and
MUCAPE values aoa 500 J/kg. Will maintain PoPs around 50% across the
Tri-Cities and Thumb, down to 20% closer to the M59 corridor, given
uncertainties with how far south precipitation will expand as top
down saturation will have to overcome a stout low-level dry layer.
Zonal flow behind the low will advect milder air into SE MI,
promoting daytime high temperatures in the 70s. Low-end shower and
storm chances will exist Sunday afternoon and early evening on the
boundary of a cold front favored away from the Tri-Cities and Thumb.
If storms come to fruition they will bare watching given favorable
daytime time heating with 40 knot 1-6 km bulk shear in place. Warmer
than normal temperatures will carry on into the midweek period along
with a brief period of dry weather. Rain and thunderstorm chances
increase Tuesday and Wednesday in response to lee cyclogenesis that
will develop and push a low pressure system into the Midwest.

MARINE...

Strong low pressure (977 MB) along the Ontario/Quebec border this
afternoon, but the low has pretty much bottom out and should begin
to slowly weaken as it moves off into Quebec. Solid gale force wind
gusts across the Central Great Lakes, and still several more hours
for winds to increase as further cold advection occurs. There will
likely be a few isolated gusts over central/northern Lake Huron, but
do not see the duration long enough to support storm warning.
Widespread rain may also help with precipitation drag.

Gradient gradually loosens over the course of Saturday as the low
slides into Quebec with weak surface high pressure building in its
wake. While winds likewise slowly weaken, gale potential lingers
over northern/central Lake Huron into early Saturday afternoon.
Calmer conditions take hold by Saturday night before a much weaker
low drops out of Canada into the central Great Lakes Sunday. System
brings chances for additional light showers and a few thunderstorms
daytime Sunday. No wind headlines expected with this system as gusts
generally top out around 20kts.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Wind Advisory until midnight EDT tonight for MIZ047>049-053>055-
     060>063-068>070-075-076-082-083.

Lake Huron...Gale Warning until 10 AM EDT Saturday for LHZ421-422-441>443-
     462>464.

     Gale Warning until 4 PM EDT Saturday for LHZ361>363.

Lake St Clair...Gale Warning until 10 AM EDT Saturday for LCZ460.

Michigan waters of Lake Erie...Gale Warning until 4 AM EDT Saturday for LEZ444.

     Low Water Advisory until 10 PM EDT this evening for LEZ444.

&&

$$

AVIATION.....CB
DISCUSSION...AM
MARINE.......SF


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.