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770
FXUS63 KDTX 121951
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
351 PM EDT Sun May 12 2024

.KEY MESSAGES...

- Showers and scattered thunderstorms increasingly likely throughout
Monday morning as a cold front drops through the region. This first
round of precipitation will be favored along or north of M59.

- Renewed rainfall, heavy at times, is possible Monday afternoon
into Tuesday morning as the front stalls across central Lower
Michigan.

- Showers and thunderstorms continue Tuesday as the front exits the
region. Cooler than normal temperatures follow Tuesday and Wednesday.

&&

.DISCUSSION...

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NVA in the wake of the departing upper-level trough has bolstered deep
layer subsidence through the afternoon, promoting generally clear
skies which have allowed temperatures to peak into the upper 60s to
lower 70s, outside of the Thumb with the lake induced thermal
influence. A prominent but narrow corridor of mid-level clouds will
briefly filter in across SE MI through the later afternoon and
evening hours along the edge of a weak and fleeting shortwave, with
a warm front then pushing in shortly after the departure of the
wave. The 12Z DTX RAOB displays a prominent dry layer from h850
which is maximized up around h500. Precipitation is not expected
with either of these features.

The potential for rain and thunderstorm chances will be centered
late tonight into tomorrow morning (04Z - 12Z) along a cold front,
which is projected to push through central lower Michigan before
stalling. The expansion of the llj along the frontal boundary will
elongate hodographs which will support moderate, partly crosswise
low to mid-level shear with otherwise weak deep layer shear. However
as is typical with unfavorable nocturnal timing of cold fronts,
SBCAPE values will be nil with MUCAPES aob 500 J/kg and the
effective inflow layer will be above the surface thus only an
elevated portion of the shear profile can be realized. The severe
weather threat will be very low given the above, but with some
elevated CAPE and mid-level lapse rates ranging between 6-7 C/km,
thunderstorms will be possible within the line. SWODY1 clips the
northwest portion of Midland and Bay Counties within a marginal
risk. If storms overachieve, hail up to an inch would the primary
threat given the projected elevated nature of activity.

This frontal boundary will be the focal point for renewed rain and
thunderstorm chances by tomorrow afternoon, with the vast majority
of model guidance places this boundary just north of M59, falling
somewhere along the Flint-Tri Cities-Thumb region. PW values are not
remarkable in the sense that they fall within climatological norms,
however, near parallel cloud depth/shear vectors relative to the
boundary coupled with the enhanced theta-e environment with MLCAPE
values rising between 500-1000 J/kg supports the potential for
repeated rainfall, heavy at times with any convective activity. The
Metro region down into the border is favored to stay dry for at
least the first half of the day given it is entrenched in the warm
sector away from the boundary, but rain and possible thunderstorm
chances turn more likely late tomorrow night into Tuesday once both
the low pressure fills in across the Tennessee Valley while the cold
front then starts to move southeast in response to the building high
pressure system over Ontario. Have bumped up daytime high
temperatures to or slightly above 80 degrees across the Metro region
given higher confidence for rainfall to hold off into later on in
the day. Precipitation chances continue into Wednesday morning,
before high pressure fills in across the Great Lakes. Please see the
hydrology section for additional information.

A building shortwave ridge will help support dry conditions through
Thursday, with the next chance for showers and thunderstorms
entering Friday and Saturday, initially from a shortwave, with a
possible low pressure system impacting the state by the start of the
weekend. Confidence on the development and position of low pressure
system is very low at this time with large variance noted between
ensembles.
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&&

.MARINE...

High pressure today maintains dry weather and light southerly flow.
The next low pressure system however will gain influence overnight
with rain moving in ahead of a stalling cold front. As the front
stalls, expect continued rain showers especially for locations
within and south of Lake Huron. Slow progression of the cold front
lends to a gradual shift to northwest flow by Tuesday evening. High
pressure then moves in Wednesday to afford drier weather for mid-
week. There may be a need for localized Small Craft Advisories late
Tuesday-Wednesday as wind gusts and waves ramp up.

&&

.HYDROLOGY...

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An active period of weather will be centered on a cold front moving
into Lower Michigan late tonight which then stalls in central to
southern Lower Michigan Monday and Monday night. Showers and
thunderstorms will be numerous along the front, especially Monday
evening and early Tuesday morning, when locally heavy rainfall
totaling 1-2 inches is possible. Predictability is moderate on this
overall rainfall scenario (numerous showers and some thunderstorms
along the front), but still low on precisely where the front will
line up. The current guidance suggests the frontal boundary stalling
north of M59, likely across the Tri-Cities to Thumb. A broad area of
minor flooding potential is centered on the Monday night to Tuesday
morning time period for Southeast Michigan.
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&&

.PREV DISCUSSION...
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Issued at 331 PM EDT Sun May 12 2024
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&&

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

$$

DISCUSSION...AM
MARINE.......MV
HYDROLOGY....AM


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at www.weather.gov/detroit.