Detroit, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

866
FXUS63 KDTX 171914
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
314 PM EDT Thu Apr 17 2025

.KEY MESSAGES...

- Showers and possible thunderstorms expected late tonight and
Friday morning.

- Warm and windy on Friday with high temperatures well into the 70s
to near 80 degrees. Southerly wind gusts of 30-40 mph expected in
the afternoon.

- There is a marginal to slight risk of severe thunderstorms Friday
night, mainly after 10 PM.

&&

.DISCUSSION...

Ongoing long wave trough amplification across the northern and
central Rockies will result in downstream strengthening of the deep
layer west-southwest winds across the Mississippi Valley and Great
Lakes region tonight into Friday. This will drive a plume of mid
level moisture across Se Mi this evening into the overnight. This in
conjunction with steepening mid level lapse rates will be at least
supportive of ample returns on radar. Residual dry air in the low
levels associated with departing sfc high pressure will be a
limiting factor for how much if any showers will be able to reach
the sfc. There will be some degree of stability in the nocturnal
boundary layer to keep the stronger winds elevated (35-40 knots at
1k feet). The gradient flow will limit nighttime lows in the
upper 40s/low 50s. Hi res model solutions are in reasonable
agreement in driving a convectively induced short wave across
cntl/nrn Lower Mi late tonight/early Fri morning. Increasing elevated
instability along the nose of the low level jet will sustain some
degree of convection across Lower Mi. While the better forcing will
be across central Lower Mi, convective chances will extend south into
metro Detroit along the mid level instability axis.

The deep elevated mixed layer(EML) observed across the southern
Plains this morning is forecast to lift into Se Mi late Fri morning
into the afternoon. Model soundings across Se Mi indicate this will
result in a strong capping inversion, inhibiting convective through
the afternoon. While there will be low level moisture advection
through the day, the NAM remains much more bullish with the low cloud
development under the capping inversion. GEFS members are more
supportive of less low clouds, with a warmer better mixed boundary
layer. This suggests highs over most of the area well into the 70s
(it is noted that there are a few ensemble members that drive highs
into the low 80s) and windy conditions (sfc gusts over 30 MPH). The
elevated mixed layer is forecast to exit to the east Friday night.
This will open the door to convective development along a slow moving
sfc cold front forecast to move into Se Mi overnight. Deep layer
sheer will remain strong through the night (bulk shear of 50- 60
knots). Waning surface based instability due to the loss in diurnal
heating will limit the severe wx risk, which is why a portion of the
area was downgraded from Slight to Marginal in the SPC Day2 Outlook.

The northern branch of the mid level trough axis will traverse the
northern Great Lakes Saturday and Saturday night, driving high
pressure into the region from the north in its wake and bringing
cooler and much drier conditions to Se Mi. This will also force the
sfc cold front south of the forecast area. However, the elevated
portion of this front will warrant continued chances for showers
through the first half of the day Saturday across the southern
portions of the forecast area. A compact mid level low and associated
surface occlusion is forecast to lift into the Great Lakes region
late Sunday into Monday. Recent trends have been more westward with
this system, taking is across the upper Mississippi Valley/wrn Great
Lakes. This solution would still drive the warm conveyor into Se Mi
and support a chance of showers Sun night and Monday.

&&

.MARINE...

Benign marine conditions continue through the evening as departing
1024 mb surface high pressure reaches the mid-Atlantic. A pattern
shift then begins overnight, first indicated by increasing southeast
gradient flow. This brings wave heights to Small Craft Advisory
thresholds, while influx of the low level jet also increases wind
gusts toward 25 knots for most of Friday. First round of showers and
possible thunderstorms arrives with this low level jet early Friday
morning, with a longer duration period of precipitation possible
Friday night into Saturday morning along the slow-moving system cold
front. A few of these storms may be strong to severe, more likely
over northern Lake Huron where the front arrives earlier Friday
night. An active frontal zone and upper level pattern keeps
precipitation chances going through the evening, though wind and
wave action will subside below advisory thresholds.

&&

.PREV DISCUSSION...
Issued at 119 PM EDT Thu Apr 17 2025

AVIATION...

Departure of high pressure maintains dry/VFR conditions through the
afternoon and evening with southerly wind around 10 kt. The arrival
of an elevated warm front brings waves of mid and high clouds
through this period with mid-level ceilings become established late
this evening. Some showers will be possible through the early
morning hours but given the amount of dry air in place, much of this
may fall as virga and VFR is likely to prevail. The highest
probability for these showers will be near MBS and FNT. A
strengthening southwesterly low-level jet brings a period of low-
level wind shear overnight. This jet provides the moisture and
instability for a potential round of elevated convective showers and
thunderstorms leading up to sunrise Friday, accompanied by pockets
of MVFR ceilings and potential for IFR visibility. A strongly capped
environment sets up daytime Friday with warm, windy conditions and a
lower VFR stratocumulus deck. Southwest winds become gusty in the
afternoon to around 30 to 35 kt.

For DTW...Main aviation impact this period looks to be LLWS
overnight. Very low confidence in warm frontal showers as far south
as DTW late this evening, then the probability for convective
showers appears greatest between 10z and 14z Fri - will maintain the
PROB30 group. The better coverage is likely to occur north of DTW.
Strong capping favors a dry forecast through daytime Friday.

DTW THRESHOLD PROBABILITIES...

* Medium for ceiling 5000 ft or less Friday morning and afternoon.

* Low for thunderstorms around sunrise Friday.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 2 AM to 4 PM EDT Friday for LHZ421-422-
     441>443.

Lake St Clair...Small Craft Advisory from 8 AM to 10 PM EDT Friday for LCZ460.

Michigan waters of Lake Erie...None.
&&

$$

DISCUSSION...SC
MARINE.......MV
AVIATION.....TF


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