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478
FXUS63 KDTX 041029
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
629 AM EDT Sat May 4 2024

.KEY MESSAGES...

- Morning fog and low clouds give way to a warm Saturday with highs
in the low to mid 70s.

- Scattered showers and possible non-severe thunderstorms this
evening through Sunday morning.

&&

.AVIATION...

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The departure of a high cloud deck to the east has prompted
radiational cooling atop a shallow moist layer, which has resulted
in widespread LIFR conditions from PTK north to MBS. The onset of
daytime mixing will support a steady erosion of these clouds through
the course of the morning. Remnant moisture will then develop a
scattered to broken VFR based cu field during the afternoon. A very
slow moving frontal boundary will progress into Se Mi tonight. An
influx of low level moisture and latest model guidance is supportive
of low cloud redevelopment. Overall weak instability along this
front will limit thunderstorm chances.

For DTW/D21 Convection...Southeasterly winds today will drive weak
instability across the airspace after 21Z. Isolated thunderstorms
are possible within this environment. Forecast probabilities suggest
a 20 percent chance across the southern portions of the airspace.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms late today and overnight.

* Low in ceilings aob 5000 feet today. Moderate tonight.
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&&

.PREV DISCUSSION...
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Issued at 307 AM EDT Sat May 4 2024

DISCUSSION...

Despite the showers and clouds yesterday, high temperatures were
able to sneak into the lower 70s across most areas. Extremely dry
airmass noted with the 00z APX raob, and some of the mid level dry
air has/will make inroads into southeast Michigan. However, cool
northeast flow off Lake Huron and lingering low level moisture looks
sufficient to saturate the low levels, and deep enough moisture (5+
kft layer) to potentially trigger stray light rain showers,
especially toward the southern Michigan border, as some of the
deeper moisture over Ohio attempts to work back north late in the
day, ahead of a weak cold front moving through from the western
Great Lakes tonight. With surface capes under 1000 J/kg today and
the mid level dry slot, do not see EQL levels getting high enough to
generate thunderstorms during the daytime, but a slight chance of
non-severe storms appears warranted this evening/tonight with the
modest height falls and the slightly negative showalter values
tracking through. Stability will be on the increase 15-17Z Sunday as
the front clears the State.

Despite a fair amount of clouds today and the early morning fog,
will allow high temperatures to reach into the mid 70s across most
locations, based on the forecasted 925 MB temps of 17 C.

Westerly confluent upper level flow Sunday night preceding an upper
level ridge axis arriving early next week, supporting dry weather on
Monday and likely during the daylight hours of Tuesday before a warm
front brings widespread showers and possible thunderstorms Tuesday
evening/night.

MARINE...

An area of high pressure centered over the region this morning is
resulting in a weak gradient with light winds and waves across the
region. Elevated dew points within the stable environment have
resulted in areas of dense fog across Lake Huron and a Dense Fog
Advisory is in effect until noon today. The gradient increases this
afternoon as the high departs east, with wind organizing out of the
southeast late today into tonight. A stalled front lifts north as a
warm front tonight as a weak low moves from the upper Mississippi
Valley into the northern Great Lakes. The system then sends a cold
front through early on Sunday with a chance of showers and
thunderstorms. Wind shifts to northwesterly behind the front Sunday
afternoon, peaking at around 15 to 20 knots. High pressure then
builds in to bring quiet marine conditions for Monday and much of
Tuesday. The next warm front moves into the area late on Tuesday
with stronger easterly flow developing ahead of it.
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&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Dense Fog Advisory until noon EDT today for LHZ361>363-421-422-
     441>443-462>464.

Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

AVIATION.....SC
DISCUSSION...SF
MARINE.......TF


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