981
FXUS63 KDTX 042250
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
650 PM EDT Tue Jun 4 2024

.KEY MESSAGES...

- Showers and some thunderstorms likely Wednesday as a cold front
sweeps across the area.

- Some of the storms may be strong to severe in the afternoon and
evening with damaging winds and large hail.

- Pattern shift for the latter half of the week brings below normal
temperatures through at least the end of the week along with
periodic chances of rain.

&&

.AVIATION...

The lingering influence of sfc high pressure across the eastern
Great Lakes will maintain tranquil aviation conditions tonight with
light southeast winds. An influx of moisture will result in an
increase in higher based clouds Wed morning. An upper level trough
and associated surface cold front will traverse Se Mi late Wed
afternoon. Ample moisture and weak to moderate instability ahead of
this system will support widespread showers and thunderstorms. The
most probable time period for thunderstorms will be between 19Z and
24Z Wednesday.

For DTW/D21 Convection...An initial influx of moisture will arrive
after 12Z Wednesday morning. This combined with decreasing
instability will support isolated thunderstorms between 12Z and 17Z
Wednesday. The probabilities for thunderstorms then becomes high
during the 20Z to 24Z time frame. Current indications suggest a slow
moving line or cluster of thunderstorms impacting the airspace
during this time period.

DTW THRESHOLD PROBABILITIES...

* Moderate in thunderstorms Wednesday afternoon and evening.

&&

.PREV DISCUSSION...
Issued at 354 PM EDT Tue Jun 4 2024

DISCUSSION...

The systems that will be responsible for the upcoming showers and
thunderstorms late tonight through Wednesday are clearly defined on
satellite this afternoon. A southern stream mid level low is
tracking from northern MO this afternoon into WI tonight. Meanwhile
the more dominate northern stream trough is cutting through the
northern Plains. The latter will absorb the former as they pass
through the Great Lakes late Wednesday. We`ve been watching this
scenario play out in the models for a couple days now with not too
much change, but now as we get closer the small changes have more
notable impacts.

Since yesterday the trend has been to slow the northern trough which
allows the MO low to lift north farther to the west of SE MI which
draws the stronger low level jet forcing west as well as it also
keeps the trough more neutrally tilts longer vs going negative early
in the day. This still draws the warm frontal/theta e gradient up
across the MI/OH border early Wed morning and through the Thumb
early afternoon which introduces a wealth of moisture into the
region. This will be the first chance of showers and storms as it
won`t take much to to initiate precip with this sharp of a theta e
gradient. But, the greater 850mb forcing looks to hold to our west
and the greater 700mb forcing looks to skirt by to the east so
overall lack of stronger forcing will keep us with a chance pop.

We then get warm sectored with PWATs climbing to near 2 inches with
some models and dewpoints in the mid 60s. Forecast soundings are
pretty steady with around 1000 J/kg of CAPE and around 30 knots of
unidirectional shear, both of which are adequate for strong storms
along the cold front as it sweeps through. A few storms may become
severe with damaging wind gusts and hail up to 1 inch and the latest
SPC day 2 outlook keeps us in a Marginal designation for severe
weather. Storms should be tracking to the northeast along the front
while the entire line drift east so training of storms will be
possible and with the amount of moisture present in the atmosphere,
could see some flooding concern. WPC currently has us in a Marginal
Risk of Excessive Rainfall in the Day2 outlook.

Precip should come to an end for the most part after 02Z, with a
slight chance of some lingering activity over the eastern Thumb. A
secondary trough will then pivot down through the area late
Wednesday night into Thursday morning so there will be additional
chances of rain during that time.

The strong trough then becomes negatively tilted as it stalls over
the region and eventually cuts off for the weekend. The energetic
northern stream will pump a series of waves through the weekend and
even into next week keeping periodic chances of precipitation in the
forecast. A surge of cold air for the latter half of the week will
drop temps below normal with highs on Friday about 10 degrees below
normal in the mid 60s. Ridging over the Plains then starts pushing
back slowing into the region, moderating temps overtime back to near
normal next week.

MARINE...

A ridge of high pressure will maintain dry weather for the remainder
of the day, outside of northern Lake Huron, where showers and
thunderstorms will be possible. This will also maintain light
southeast flow through the remainder of the day, outside of the
northern thunderstorms activity. A major pattern shift will then
take place on Wednesday once a cold front moves over the Great Lakes
Wednesday afternoon through evening. Numerous to widespread rain
showers and embedded thunderstorms are expected ahead of and along
the front. Additionally, there will be a marginal risk for severe
weather. The strongest thunderstorms will be capable of producing
wind gusts in excess of 30 knots and small hail.

Passage of the front will veer wind direction from the southeast to
the southwest. A cooler air mass will then gradually setup over the
Great Lakes through at least the end of the week while stronger wind
set up aloft. The enhanced mixing depths will bring breezy
conditions over the nearshore zones on Thursday with gusts on the
order of 20-30 knots. Small Craft Advisories will likely be needed.

HYDROLOGY...

A line of showers and thunderstorms is expected to pass through
southeast Michigan Wednesday afternoon and evening ahead of a cold
front. A very moist airmass will help these storms become efficient
rain makers with widespread rainfall amounts between 0.25 to 0.50
inch expected, although localized higher amounts around 1 to 2 inch
are not out of the question with any storms training over the same
areas. Brief and minor flooding of prone urban and low-lying areas,
ponding of water on roadways, and rises in area rivers are possible.

&&

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

$$

AVIATION.....SC
DISCUSSION...DRK
MARINE.......AM
HYDROLOGY....DRK


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at www.weather.gov/detroit.