845
FXUS63 KDTX 060310
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1110 PM EDT Sat Oct 5 2024

.KEY MESSAGES...

- Chance (40-50%) for some scattered showers or a thunderstorm this
  morning across the Tri-Cities and northern Thumb. Low chance
  (<20%) for a shower for locations south by the mid to late morning
  hours.

- Breezy conditions starting this morning, ramping up through the
  afternoon. Sustained winds of 15-20 mph, with gusts around 30 mph,
  sporadic up to 35 mph.

- Dry and more seasonal temperatures Monday through the middle of
  the week.

&&

.AVIATION...

VFR conditions start this TAF period with FEW-SCT clouds at around
7.5kft present ahead of the warm front. Winds then turn southerly in
the warm sector ahead of a cold front where a short period of MVFR
ceilings will be possible along with some light rainfall early to
mid morning. Latest hi-res models struggle to produce much
precipitation, especially south of the Tri-Cities. Radar trends also
showing bulk of precipitation across northern WI and northern MI.
Thus, will leave -RA out of TAFs with the exception of MBS and have
TEMPO MVFR ceiling groups for remaining terminals. Strong low level
jet winds of 40+ knots also arrive early this morning resulting in
mention of LLWS through about 12Z until better surface gusts take
hold. Westerly gusts of 25-30 knots develop by mid-late tomorrow
morning and continue through the afternoon as rapid clearing occurs
behind the front. Winds settle out of the northwest by Sunday evening
with a gradual decrease in speeds.

For DTW/D21 Convection... Probability remains low for any
precipitation and associated embedded thunderstorms late
tonight/early Sunday morning. Severe weather is not expected. The
gusty west winds by tomorrow afternoon may approach crosswind
thresholds at times.

DTW THRESHOLD PROBABILITIES...

* Moderate for short period of ceilings at or below 5000 feet early
  tomorrow morning.

* Low for crosswind thresholds tomorrow afternoon.

&&

.PREV DISCUSSION...
Issued at 352 PM EDT Sat Oct 5 2024

DISCUSSION...

Pleasant fall conditions characterized by sunny skies and
temperatures in the upper-60s to lower-70s continue this afternoon,
under the influence of a shortwave ridge and subsequent surface high
pressure, which is now centered across western Ontario. High
pressure will progress east before washing out over the Atlantic
tonight, with attention then turning to the upper-level low which
will track eastward across the southern Canadian Provinces, settling
over the Hudson/James Bay tomorrow afternoon. Progression of this
system will result in a tightening pressure gradient over the Great
Lakes which will ramp up warm air advection throughout the morning
hours as h850 temperatures around 12C are ushered over southern
Michigan. The strength of waa will initially offset then totally
negate the typical overnight diurnal cooling, holding overnight lows
in the upper 50s through the early morning hours, with subtle
warming then expected through the mid to late morning hours once
surface winds veer from southeast to southwest.

Moisture transport will be aided by a potent llj with a projected
magnitude of 60-65 knots at h850, maximized across north and central
Lake Huron through the morning hours. This will bring a corridor of
enhanced theta-e across Michigan, especially through northern lower
Michigan, where showers and embedded thunderstorm are likely.
Intensity of the llj will wane through the late morning hours as an
upper-level trough and cold front move in across SE MI along the
cyclonically sheared side of the llj. Model-guidance continues to
back off on rain chances for Southeast Michigan outside of portions
of the Tri-Cities and northern Thumb, tied to the better moisture
depths and forcing, but overall the narrow scale of forcing, narrow
window to interact with the enhanced theta-e will continue to
preclude any meaningful PoPs in the ongoing forecast. Will maintain a
chance (40-50%) across the Tri-Cities and northern Thumb, with low
chance (sub-20%) for locations south.

After the passage of the initial front/upper-level trough, low-level
sounding profiles turn more neutral to slightly unstable, enhancing
mixing depths and tapping into the stronger winds aloft while deep
layer subsidence increases. Breezy condition start through the mid
to late morning hours while temperatures rise into the mid to upper
70s across most of SE MI as we briefly reside in the warm sector.
This will be aided by a window of sunny skies during the afternoon
hours. Deep column cold air advection then moves in from northwest
to southeast between 17Z - 20Z, which will bring peak wind gusts
around 30 mph, isolated 35 mph, as temperatures then begin to fall
through the afternoon hours. This will lead to overnight lows in the
mid 40s by Monday morning while winds and gust potential decrease in
intensity. Temperatures will be cool enough to activate lake
moisture off of Huron coinciding with the tail-end of the day
tomorrow to bring strato-cu/stratus tomorrow evening into Monday
morning.

Outside of low-end chances for lake effect showers along the
northern Thumb Monday evening through Tuesday, SE MI will enter an
extended period of dry and sunny conditions as high pressure builds
in across the Midwest while the thermal trough holds overhead through
the midweek. Highs in the low 60s, lows in the low 40s (mid to upper
30s possible by Wednesday morning) are expected during this time
frame.

MARINE...

Low pressure gains influence today with an approaching cold front
just now reaching the western edge of Lake Superior. Upstream gust
observations at issuance are around 30 knots, but with the low level
jet expected to strengthen overnight these gusts will strengthen to
gale force by the time the front reaches Lake Huron. A few gusts may
approach 45 knots during the peak of the event, right around
daybreak Sunday morning, over northern Lake Huron. Widespread
showers and thunderstorms along the front will help mix down gusts
as well. A break in gust potential is anticipated just behind the
mid-morning frontal passage as flow shifts from south to northwest.
Mixing depths will gradually grow latter half of Sunday, priming the
environment for gusty conditions as a second trailing low level jet
reaches Lake Huron Sunday evening. Forecast gusts have trended up
over the past 24 hours for Sunday night-Monday morning, which may
require an extension of the Gale Warning for northern Lake Huron.
Unsettled conditions persist through early next week as upper level
troughing holds in place.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning until 10 AM EDT Sunday for LHZ361-362.

     Gale Warning until 10 AM EDT Sunday for LHZ363-421-422-441-442-462-
     463.

     Small Craft Advisory until 10 AM EDT Sunday for LHZ443.

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

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

&&

$$

AVIATION.....AA
DISCUSSION...AM
MARINE.......MV


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