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704
FXUS63 KDTX 260714
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
314 AM EDT Sun May 26 2024

.KEY MESSAGES...

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- Showers with embedded thunderstorms move into the region after 4 pm
  and persist into this evening.

- There is a Marginal Risk of severe weather late today into tonight
  from I-69 south with a Slight Risk for Lenawee and Monroe counties.

- There is also a Marginal Risk of excessive rainfall. See the
  Hydrology section of this AFD.

- The Memorial Day outlook calls for cooler, more seasonable
  temperatures with scattered showers and thunderstorms.
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&&

.DISCUSSION...

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A strong shortwave will eject from NE/KS into the western/northern
Great Lakes late today into tonight. This mid level feature will
become negatively tilted as it pivots around upper low pressure
centered near Lake Winnipeg. This shortwave will induce cyclogenesis
over WI late today with the surface low then tracking into northern
lower MI and deepening to near 990mb by Monday morning. A band of
convection is expected to arc into the area along this trough axis
later today (arriving between 4pm-6pm).

Initially, this band of showers and thunderstorms will tap some
degree of surface instability along/south of a warm front lifting
north through the Ohio Valley. This front, however, will struggle to
lift into lower MI late in the day and band of convection will have
to rely increasingly on the advection of elevated instability into
its flank as a southwesterly LLJ pivots into the area by evening.

While this will limit severe potential, given the fact that wind
shear increases to near 40 knots as the wind field strengthens in
response to the encroaching shortwave, any notable push of unstable
air into the region (surface based or not) should support a small
chance of severe weather into at least portions of the forecast
area. As such, the areas north to the I-69 corridor are outlooked
for a marginal risk of severe weather with the far southern part of
the area outlooked for a slight risk in anticipation for spotty
large hail and/or damaging wind gusts with a few of the storms.

The most concentrated convective activity will focus on the evening
period with just scattered showers and a few thunderstorms possible
overnight into Monday as the surface low pressure reaches northern
lower MI and begins to occlude. Mild weather will continue Monday,
but a cold front will pivot east through the area during the day.
This will set up a temperature gradient from the mid/upper 60s over
the Saginaw Valley to the lower/mid 70s over east/southeastern parts
of the area. Gusty southwest to west winds will accompany this front
with wind gusts to 30 mph or so by afternoon.

The aforementioned upper low pressure system near Lake Winnipeg will
pivot southeast into the area into the midweek period in the wake of
a fast moving Pacific shortwave that races into the deepening upper
trough over the area. This will bring cooler temperatures in the 60s
to near 70 from Tuesday into Thursday. There will also be a chance
of showers and a few thunderstorms from Monday night into Tuesday
night, but peaking late Tuesday as the remnants of this main upper
low shift through the area.

A substantial upper level ridge shifts east over the area by late in
the week bringing a return of temperatures in the 70s to around 80
from Friday into next weekend. The next notable Pacific shortwave
will more than likely impinge on the area by sometime next weekend.
This will bring some chance of showers/thunderstorms back into the
forecast towards the tail end of this 7 day forecast.
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&&

.MARINE...

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Easterly winds today as brief high pressure moves across the region.
The next low pressure system is expected to impact the region
beginning this evening. Warm frontal passage overnight is expected
to strengthen winds over the lake and bring chances for showers and
storms. Low level flow will be quite strong with this system,
reaching up to 40 knots 1000 feet above the surface. Small
temperature inversion will keep some of the wind at bay, but
stronger gusts will still have little trouble mixing down. Monday
the cold front will move through, bringing further chances for
showers/storms as well as surface winds up to 20 knots over Saginaw
Bay and northern Lake Huron. Winds will have a harder time mixing
down on Monday, but errant gusts to 30 knots are still possible.
Small Craft Advisories will likely be needed Monday, but there is
still uncertainty in the timing and extent of the impacts.
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&&

.HYDROLOGY...

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Showers and thunderstorms are expected late today into tonight as a
strong low pressure system lifts into the area. Locally heavy rain
will be possible with some of the thunderstorms as moisture quality
within the atmospheric column improves into this evening. Forecast
basin average rainfall amounts range between one quarter of an inch
to three quarters of an inch, but higher amounts in excess of 1 inch
will be possible in a few stronger storms. Forecast adjustments are
likely due to the convective nature of the rain. The main concern
would be for localized flooding of prone urban areas across the
Detroit Metro region.
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&&

.PREV DISCUSSION...
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Issued at 126 AM EDT Sun May 26 2024

AVIATION...

Dry air advection and upper level jet driven subsidence is
supporting surface high pressure over Southeast Michigan tonight.
Models are suggesting some near surface saturation may be possible
at daybreak as a weak convergence axis backdoors into the area off
of the Great Lakes. Confidence is low but did introduce a 5sm ground
based br/hz at dawn for the Detroit terminals. Strong synoptic scale
forcing for ascent with strong absolute vorticity advection will
bring an arc of showers and thunderstorms in Southeast Michigan
Sunday afternoon. The forecast includes timing beginning after 21Z
at the Detroit terminals and 23Z for KFNT and KMBS.

For DTW/D21 Convection...The potential for thunderstorm activity
will increase after 21Z Sunday at DTW and 23Z at KMBS/KFNT.

DTW THRESHOLD PROBABILITIES...

* None.
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&&

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

$$

DISCUSSION...DG
MARINE.......BC
HYDROLOGY....DG
AVIATION.....CB


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