331
FXUS63 KDTX 231919
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
319 PM EDT Sun Jun 23 2024

.KEY MESSAGES...

- A cooler and less humid air mass gradually builds into Lower
Michigan today and tonight.

- High temperatures in the upper 70s to lower 80s Monday are right
around normal for mid to late June.

- Showers and thunderstorms become active again during the mid week
period.

&&

.DISCUSSION...

Cold front moves off to the southeast today bringing relatively
drier air to the CWA and helping drop dew points from last week`s
muggy 70 degrees. ThetaE values are set to drop another 10-15
degrees overnight, and in combination with some overnight clearing,
will allow temperatures to drop into the low 60s/upper 50s tonight
for the first time in a week. Isolated showers spilling off the cold
conveyor belt of the departing low pressure system are possible
through the evening tonight, mainly in the Thumb and over Lake
Huron. Showers are expected to be weak and will produce less than a
tenth of an inch.

By sunrise Monday showers will be over with and skies will be mostly
clear. Ridging in full effect with a broad high pressure system will
keep winds calm. Seasonal temperatures of upper 70s to 80 degrees
could push slightly higher into the low 80s. Ridge axis passes
overhead Monday afternoon and hands over control to an upper level
low over Canada that will bring the next disturbance to the region.

Divergence aloft will support the development of the next low
pressure system and allow it to bring showers and storms to the
Great Lakes on Tuesday. Warm and moist air will advect in and push
dew points into the upper 60s/low 70s. Temperatures are set to
approach 90 Tuesday afternoon, although cloud cover could limit the
heating potential. However, the heat and moisture will help
destabilize the atmosphere and produce an environment capable of
producing strong storms. CAPE values ranging between 2000-3000 J/kg
are set to move overhead, although hi-res models will have a better
idea when they come into the time range. There has also been some
signal to show that storms may split the CWA, opting to stay both
north along the area of greater divergence aloft and south in the
higher CAPE environment. In terms of rainfall, ensemble guidance
gives a 50th percentile value between 0.25" and 0.5" of QPF for this
system, but higher amounts are easily possible. The DTX CWA is under
a Marginal Risk for severe weather for this system, with parts of
GRR and IWX nearby under a Slight Risk. The cold front sticks around
for a bit and brings chances for rain through Wednesday before
moving across the area Wednesday evening.

Behind the front, weak ridge moves in an promotes high pressure. Dry
air will be in place, keeping clear skies and dew points in the 50s.
Seasonal to below normal temperatures for Thursday and Friday with
ensemble means giving slightly below climatological normal high
temperatures. Low cloud cover leading to full insolation may allow
for temperatures to push closer to normal and touch 80 in places.
Trough off to the west helps develop a low pressure system set to
track from MT/ND into southern Canada. That system will bring the
next chances for showers and storms via warm and cold fronts moving
across the Great Lakes over the weekend.

&&

.MARINE...

Area of low pressure now over Ontario, heading into Quebec, pulled a
cold front across the region this morning.  A secondary cold front
is rotating south down through Lake Huron. This will keep elevated
northerly flow persisting through the rest of the day before high
pressure building in from the west can settle the wind and waves
back down. High pressure will center over the region on Monday
bringing improved conditions but the next frontal passage comes
Tuesday bringing the next chance of increased southwesterly flow and
thunderstorms.

&&

.PREV DISCUSSION...
Issued at 105 PM EDT Sun Jun 23 2024

AVIATION...

The cold front has cleared the region early this afternoon ushering
in a cooler airmass that has supported persistent MVFR ceilings
across lower MI. Strong advection will continue to support breezier
conditions with west-northwest winds gusting up to around 25kts
through this afternoon. Daytime heating and a drier airmass settling
into the area will gradually lift these cigs into VFR into this
evening with coverage diminishing overnight as high pressure builds
in. This high also results in northwest winds turning much weaker,
aob 10kts, going into Monday. A few isolated showers remain possible
during the daylight hours today though best potential resides east of
the TAF corridor over the Thumb, so have not included mentions for
any sites.

For DTW/D21 Convection...No convection is expected during the
forecast period.

DTW THRESHOLD PROBABILITIES...

* High for ceilings aob 5kft today, low this evening.

* Moderate to reach crosswind thresholds from ~280-290 degrees this
  afternoon. Low by evening.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422-
     441>443.

Lake St Clair...Small Craft Advisory until 10 PM EDT this evening for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EDT this evening for LEZ444.

&&

$$

DISCUSSION...BC
MARINE.......BC
AVIATION.....KDK


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at www.weather.gov/detroit.