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105
FXUS63 KDTX 291855
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
255 PM EDT Mon Apr 29 2024

.KEY MESSAGES...

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- Potential exists for showers and thunderstorms to develop through
  the evening. There is a marginal risk for storms to become severe
  during this time. Damaging wind gusts will be the main threat,
  although a brief tornado cannot be ruled out across the thumb.

- Dry and slightly cooler Tuesday.

- Well above normal temperatures remain through the week.
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&&

.DISCUSSION...

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A brief infusion of deeper moisture affording a modestly unstable
ambient profile late this afternoon. Inbound pre-frontal trough and
850 mb flow greater than 40 knots will continue to capitalize on
this weak buoyancy to produce clusters of showers, with isolated
thunderstorms, over the next several hours. Overall convective vigor
maintains dependence on overcoming generally limited mid level lapse
rates, but potential remains for isolated cells to attain some
updraft depth given the steeper low level lapse rates. As noted in
the AM update, background wind field more than sufficient to offer
organization to any vigorous updrafts. Existing marginal Risk will
continue to highlight stronger wind gust potential, while locally
backed flow across the thumb maintains at least lower potential for
storms to attain rotation and brings a non-zero threat of a brief
tornado within this corridor over the next couple of hours. A
secondary window for sub-severe convection arrives overnight with the
actual cold frontal passage.

Southeast Michigan falls within the immediate post-cold frontal
environment early Tuesday, as height fall emanating south of the
parent circulation exiting into western Ontario expand across lower
Michigan. Ongoing dry air advection affords a steady clearing trend
of early day cloud, maintaining a respectable bounce for the diurnal
temperature curve as improving insolation potential offsets fading
cold air advection during the latter half of the day. This maintains
an airmass characterized by above average temperatures - highs mid
60s to lower 70s. Dry and stable conditions maintained through
Tuesday night under transient low-mid level ridging. Lows in the
40s.

Shortwave energy shearing across the northern great lakes will push
a weak frontal boundary through lower Michigan Wednesday. Brief
window of pre-frontal warm air advection offers a noteworthy uptick
in projected highs Wednesday /well into the 70s/. Pitiful moisture
quality associated with this frontal passage, supporting dry
conditions with simply some increase in cloud. A warm and dry
profile entrenched through Thursday as large scale ridging takes
control. Next round of height falls arrive Friday, as another mid
level circulation pivots from the north-central conus into western
Ontario. Forced ascent featured along the inbound height fall
gradient and attendant cold frontal boundary timed favorably during
peak heating portends a good opportunity for convective development
late Friday.
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&&

.MARINE...

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Weak surface low and associated surface cold front tracking through
the Central Great Lakes late this afternoon. Scattered strong
thunderstorms look to be around for another couple of hours. Will
allow small craft advisories near the tip of the Thumb to expire.
Winds in and around thunderstorms will have potential to produce
wind gusts in the excess of 35 knots however.

Southwest-west winds behind the front tonight into Tuesday morning
will usher in modestly colder air into the region, and wind gusts
should reside mainly below 20 knots, with light and variable winds
then taking over for Tuesday evening as a surface ridge arrives.

Another low pressure system looks to be tracking through Minnesota
and then into Lake Superior on Wednesday, with the cold front
swinging through the Central Great Lakes. Moisture looks lagging,
and the front appears to be weakening in the process. Thus, showers
and moderate winds will be hard to come by, with another surface
ridge then arriving Thursday morning.
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&&

.PREV DISCUSSION...
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Issued at 134 PM EDT Mon Apr 29 2024

AVIATION...

Frontal boundary moves through southern Michigan this afternoon
bringing chances for thunderstorms to all TAF sites this afternoon.
VFR conditions are expected outside the storms, with MVFR conditions
or lower possible as storms move overhead. Showers have the
potential to fill in behind the initial band of storms, but
confidence remains low on what the extent or precise timing on those
showers will be. Wherever these showers appear will have chances to
drop to MVFR conditions, with the most likely sites being KDTW and
KDET. Westerly flow will take over after the passage of a cold front
early Tuesday morning. Some light fog is expected before sunrise,
giving way to a 5000 foot cloud deck that will be present through the
day Tuesday.

For DTW/D21 Convection...A scattered to broken line of showers and
thunderstorms moves overhead between 19-22Z this afternoon. Behind
this line further showers are expected to develop and impact the
area between 0-4Z Tuesday. Although unlikely, there is still a
possibility of thunder with these secondary showers.

DTW THRESHOLD PROBABILITIES...

* Moderate in thunderstorms this afternoon, then low this evening.

* High in ceilings at or below 5000 feet this afternoon, moderate
  this evening into early Tuesday morning.
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&&

.DTX WATCHES/WARNINGS/ADVISORIES...
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MI...None.
Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421-441.

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

$$

DISCUSSION...MR
MARINE.......MR
AVIATION.....BC


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