435
FXUS63 KDTX 082237
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
637 PM EDT Sat Jun 8 2024

.KEY MESSAGES...

- Light rain will affect Southeast Michigan this evening.

- A stray shower is possible on Sunday afternoon as a weak cold
front crosses bringing slightly below normal temperatures by Monday.

- Cool and mainly dry conditions for the first half of the week are
followed by a warming trend back into the mid to upper 80s by latter
half of the week.

&&

.AVIATION...

A passing mid level short wave and low level frontal boundary within
a narrow ribbon of moisture transport has supported widespread light
rain across Central Lower Michigan this afternoon. Over the last
couple hours, the larger scale forcing and areas of light rain have
been expanding across the remainder of Southeast Michigan. This
forcing will persist through early this evening. There will then be
an abrupt end to the rain from northwest to southeast across
Southeast Michigan in the 02Z to 05Z time period as the elevated
frontal forcing exits to the southeast. Ongoing shallow low level
cold air advection behind the surface front is rapidly cooling the
low levels. There has been some degree of support from area surface
observations which suggest some areas of MVFR (perhaps some brief
intervals of IFR) ceilings developing/expanding across Se Mi this
evening. The bulk of current model solutions indicate a clearing of
any low clouds as the rain departs to the southeast.

Cold air advection within an increasing west-northwest gradient and
deepening afternoon mixing depths will support an increase in winds
by Sunday afternoon. Peak gusts in the 25 to 30 knot range looks
reasonable based on model soundings.

For DTW/D21 Convection...A lack of instability across Se Mi this
evening will inhibit thunderstorms within the area of rain now
expanding across metro airspace.

 DTW THRESHOLD PROBABILITIES...

* Moderate for ceilings aob 5000 feet this evening.

&&

.PREV DISCUSSION...
Issued at 304 PM EDT Sat Jun 8 2024

DISCUSSION...

Area of showers continues to fill-in from north to south this
afternoon as local height falls ensue due to a broad upper low
crossing Ontario. The main jet axis aloft supporting the shortwave
feature extends across most of the northern tier of CONUS today
while a speed max emerges over the Upper Midwest and elongates
across southern Lower Michigan. Region of peak ThetaE advection
arrives after 22Z this evening along the leading edge of an elevated
warm frontal boundary. This boundary makes minimal northward
progress, but should offer enhancements to saturation via isentropic
ascent along the frontal surface. Overall, expect rather benign
rainfall rates with shower activity tonight given prior dryness
marked by the 08.12Z KDTX RAOB which sampled a PWAT of 0.75 inches.
SPC Mesoanalysis suggests the core of the moisture plume (+1.00 inch
PWATs) has already advected into western Lower with HREF supporting
an eastward progression/fold this evening. A survey of instability
based on several deterministic sources and representative forecast
soundings highlight positive CAPE values remaining just south of the
IN/OH/MI border, therefore will continue to advertise a thunderless
forecast. Made minor adjustments to PoPs to slow the arrival of
showers along/south of I-94 and accelerated the phase-out of PoPs
upon departure of the wave after midnight.

The aforementioned upper low dislodges thanks to the amplification
of a ridge axis over north-central Canada which merges with a higher
amplitude ridge over The West. This drives additional CVA through
the Great Lakes Sunday while an area of surface troughing emerges.
Westerly gradient flow strengthens after 16Z while a mixed-layer
lifts to 5 kft AGL, intersecting a modest low-level wind field of
30+ knots. Breezy conditions are likely as peak gusts approach 30
mph once a weak cold front drops through and veers winds
northwesterly. Can`t completely rule out a few spotty
afternoon/evening showers, but moisture quality is rather meager,
thus any isolated shower activity should be rather light in
character. A cooler airmass settles in Sunday night with lows
dipping below 50F for some areas in spite of lingering cloudiness.
Also can`t rule out a few sprinkles along the shores of southern
Lake Huron given the brief lake-influence setup.

Sprawling high pressure spills across the Upper Midwest Monday and
Tuesday offering high-confidence in a dry forecast. Air parcel
trajectories tracing back into northern Canada maintain cooler-than-
normal conditions Monday followed by a shift to a return-flow setup
by Tuesday afternoon which marks the initiation of a warming trend
through the remainder of the week. Highs break into the 80s by
Tuesday with medium-range solutions (GEM/ECMWF) supporting the
potential for MaxTs to approach 90F for Metro Detroit by Thursday as
850 mb temps approach 19C. A cold front and the chance for storms
increases Thursday night into Friday.

MARINE...

Widespread showers continue over the region this evening before
shifting towards the southern Great Lakes overnight as weak low
pressure slides across the region. Drier conditions generally
redevelop daytime Sunday with only isolated to scattered showers
possible mainly over the northern half of Lake Huron tied to
lingering, deepening low pressure over Quebec. This low tightens the
local gradient resulting in an uptick of northwesterly winds latter
half of the day Sunday into Sunday night. Overall, 20-25kt gusts
expected over the region though areas for greater achievement
pushing towards 30kts are the Saginaw Bay (due to the warmer waters)
as well as northern Lake Huron given the favorable fetch. Lighter
winds, at or below 20kts, then arrive daytime Monday as high
pressure builds overhead. This high remains in place for the first
of half of the work week.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....SC
DISCUSSION...KGK
MARINE.......KDK


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