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068
FXUS63 KDTX 050403
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1203 AM EDT Sun May 5 2024

.KEY MESSAGES...

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- Scattered showers and possible non-severe thunderstorms late
  tonight through Sunday morning.

- High pressure builds in the latter half of Sunday through Monday
  bringing drier conditions and closer to average temperatures.

- Developing low pressure over the Midwest brings widespread shower
  and thunderstorm chances Tuesday into Wednesday.
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&&

.AVIATION...

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A slot of clear sky over a cool and moist boundary layer has a wide
range of aviation conditions in place to begin the late night
period. This favors expansion of IFR stratus and fog ahead of a cold
front moving in from western Lower Mi. The front brings a weakening
band of showers with the chance of a thunderstorm holding on this
far east. The rain pattern breaks up with eastward extent while IFR
ceiling hold on for a few hours post front. Ceiling then follows a
standard daytime improvement as cooler north wind gains traction
into the afternoon.

For DTW/D21 Convection... Rapidly waning instability is a limiting
factor for thunderstorms during the late night, although a rumble of
thunder remains possible as a cold front enters the region and moves
eastward shortly after sunrise. Thunderstorms are not expected after
mid morning as the front exits into Ontario.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms late tonight.

* High for ceiling 5000 feet or less tonight through mid afternoon.
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&&

.PREV DISCUSSION...
Issued at 241 PM EDT Sat May 4 2024

DISCUSSION...

Southeasterly lower level flow has developed this afternoon in
response to a weak cold front gradually sagging into the western
Great Lakes. This wind shift supports modest moisture advection from
Ohio, where dewpoints are holding in the mid 60s, nudging local Td`s
into the low 60s late this afternoon-evening. Even with this extra
moisture, both SB/MLCAPEs are expected to stay fairly meager,
holding closer to 500 J/kg. Forecast soundings advertise an uncapped
environment with weak column winds (<20kts thru 500mb) which
supports scattered pop-up showers and perhaps a thunderstorm into
early tonight as height falls move in from the west and a diffuse PV
anomaly lifts NE over far northwestern Ohio. Surface cold front
crosses the area Sunday morning offering another window for
scattered showers, particularly along/north of I-69 owing to closer
proximity to parent shortwave which offers slightly better upper
support/forcing compared to locales further south.

Marginally cooler airmass fallows the frontal passage as 850mb temps
drop to around 4-5C keeping highs Monday in the upper 60s to around
70 for most areas. Easterly flow beneath the surface high that will
be centered over northern lower MI by this point keeps areas
downwind of the lakes like Monroe and especially the Thumb cooler-
upper 50s to lower 60s favored.

Upper ridging and associated surface high are shunted east by early
Tuesday as a potent mid-upper wave ejects out of the Rockies into
the northern Plains. A secondary surface low is progged to develop
over the upper Midwest along the original, now stacked, low`s triple
point. This system lifts a warm front into southern lower MI over
the course of Tuesday bringing the area`s next appreciable chances
for showers and thunderstorms. The attendant cold front quickly
follows Tuesday night generating additional widespread showers and
storms. Worth noting that longer range solutions suggest a ~40kt LLJ
could work into the area from west MI setting up a higher shear
environment with severe potential dependent on how much
destabilization occurs once the warm sector fully expands of the
area. SE MI resides on the edge of SPC`s Day 4 15% severe weather
outlook so will be something to keep on eye on as we get closer.

MARINE...

An elongated area of low pressure over Wisconsin/Illinois this
afternoon tracks east into the central Great Lakes tonight, pulling
a warm front north ahead of it. This will result in an increasing
coverage of showers as well as modest southeasterly winds tonight.
There will be a slight chance of thunderstorms but severe weather is
not expected. A cold front follows on Sunday morning with continued
shower/t-storm chances and a shift to northwest wind of around 15 to
20 knots as conditions dry out for the afternoon. High pressure then
builds in to bring quiet marine conditions for Monday and much of
Tuesday. The next round of likely precip arrives late Tuesday as a
warm front moves into the area. This marks the beginning of a more
active period through the rest of the week with several disturbances
working through.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.

&&

$$

AVIATION.....BT
DISCUSSION...KDK
MARINE.......TF


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at www.weather.gov/detroit.