635
FXUS63 KDTX 230900
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
500 AM 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.

&&

.AVIATION...

Showers and any lingering stray thunderstorms come to an end this
morning. Otherwise, low level convergence with cold frontal passage
should support MVFR cigs across much of southeast Michigan, with
cloud bases rising into VFR for the afternoon, along with some
breaks in the clouds. An isolated shower or thunderstorm can`t be
ruled out in the afternoon, but very low chance of impacting any
particular airport. Westerly winds today, sustained around 15 knots,
with gusts to 25 knots at times.

Expecting VFR cigs (3-6kft) to hold on into the evening hours, with
clearing then taking place overnight as lighter northwest winds
continue to usher in drier air.

For DTW/D21 Convection...An isolated thunderstorm remains possible
through mid-late morning with the cold frontal passage, but
likelihood of occurrence remains very low.

DTW THRESHOLD PROBABILITIES...

* Very low for thunderstorms this morning.

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

&&

.PREV DISCUSSION...
Issued at 353 AM EDT Sun Jun 23 2024

DISCUSSION...

Cold front supported showers and thunderstorms exit eastward this
morning followed by cooler and less humid air for this afternoon. A
considerable cloud component follows the front across Lower MI
lending some confidence to temperature guidance that offers highs
only in the upper 70s most areas except lower 80s metro Detroit to
the Ohio border. Surface Td projections show just a gradual decrease
into the lower 60s but on breezy W-NW wind. The air mass then becomes
more fully exchanged tonight as Td drops into the 50s.

A northern stream mid level circulation and upper level jet max move
from central Canada into the upper Midwest today and across the
northern Great Lakes tonight. Agreement among the latest model runs
is improved on the associated rain pattern grazing the Thumb region
while affecting much of Lake Huron by late evening into the
overnight hours. Mid level moisture is better than adequate judging
by the structure of model 700 mb theta-e fields, and the circulation
strength provides an energetic surge of DCVA to help force the
pattern of showers. Scattered coverage on the west flank of the
moisture pattern looks good until the system exits into Ontario by
sunrise Monday.

Progression of mid level wave structures continues Monday which
brings a short wave ridge into the Great Lakes. The ridge builds
surface high pressure across the region to reinforce a low humidity
air mass. It also offers a higher than average confidence forecast
of dry weather. Guidance projected high temperatures around 80 are
right around normal for mid-late June.

The next Plains low pressure system is close on the heels of Great
Lakes high pressure Monday night into Tuesday. There is a faster
trend in model timing of arrival on the leading warm advection and
associated showers/storms into Lower MI late Monday night into
Tuesday. Onset timing predictability is affected by the larger scale
mid level pattern moving toward a more zonal configuration while
confidence in development of renewed convective activity is higher
than average. The setup looks like a textbook low level jet driven
nocturnal MCS pattern limited by a sharp west to east instability
gradient late Monday night into Tuesday morning. Low pressure
tracking through northern Ontario then pulls the instability axis
into Lower MI for round 2 Tuesday night into early Wednesday.

The cold front trailing the mid week system moves through Lower MI
by Thursday morning followed by a round of high pressure similar to
Monday with the possible exception of less short wave ridging in the
mid levels. This just means zonal flow persists within the larger
scale pattern to keep systems progressive and convectively active
across North America into next weekend.

MARINE...

A low pressure system over Lake Huron is pulling a cold front across
the Great Lakes this morning. Widespread showers and thunderstorms
will continue early this morning before the surface cold front
passes east of the area later this morning. Winds will flip around
to the north behind the front which will allow the small craft
advisory to come to an end. A secondary cold front will then drop
southward across the region tonight which may touch off a few more
showers and reinforce the northerly winds. Overall wind speeds will
hold below 20 knots as high pressure will be trying to push in from
the west helping to weaken the gradient. High pressure becomes
centered over the region Monday bringing improved conditions but the
next frontal passage comes Tuesday bringing the next chance of
increased southwesterly flow and thunderstorms.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 10 AM EDT this morning for LHZ421-422.

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

$$

AVIATION.....SF
DISCUSSION...BT
MARINE.......DRK


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