994
FXUS63 KDTX 101057
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
657 AM EDT Fri May 10 2024

.KEY MESSAGES...

- Cooler temperatures (50s to low 60s) hold through Saturday before
returning to at or above normal Sunday.

- Shower and thunderstorm chances throughout much of Saturday with
the passage of a compact low pressure system. Severe weather is not
expected.

- Another chance of showers and thunderstorms comes Monday as a cold
front drops through the area.

&&

.AVIATION...

The remaining clouds associated with eastward exiting low pressure
have stripped away from SE Mi early this morning. That leaves weak
upper Midwest high pressure in place to move into the central Great
Lakes today. A steady but light north wind brings in a cool air mass
favorable for expansive high based cumulus development as daytime
instability builds. This leads to a broken VFR ceiling above 5000 ft
by afternoon through this evening. Wind backs SW tonight as the first
sign of the next low pressure system moving in from central Canada.
It brings a band of showers late tonight with a rumble of thunder
possible. The surface system occludes overhead while supporting a
field of MVFR ceiling through Saturday morning. These clouds lift
into low end VFR with NW wind gusting near 20 knots upon passage of
the front into the afternoon.

For DTW/D21 Convection... A stray thunderstorm is possible within a
band of showers inbound with the next low pressure system late
tonight into Saturday morning.

DTW THRESHOLD PROBABILITIES...

* Low for ceiling 5000 feet or less this afternoon.

* Low for an isolated thunderstorm late tonight and Saturday
  morning.

&&

.PREV DISCUSSION...
Issued at 305 AM EDT Fri May 10 2024

DISCUSSION...

Cooler airmass (850mb temps around 2-3C) settles over the region
today as a positively tilted upper trough swings overhead. Said
active cold air advection will support the re-expansion of stratocu
cloud cover by early afternoon as lower level lapse rates steepen.
Given the airmass and more constrained diurnal insolation potential,
highs will generally be held to the lower 60s. While this setup is
favorable for the development of pockets of drizzle/light showers
during peak heating, induced mid-level ridging, from departing
Thursday low and approaching northern Ontario low, slides across
southern lower MI over the course of the daylight hours today. Bulk
of guidance is in agreement that these height rises should be
sufficient to stifle most if not all precip chances through at least
early evening hours. Height falls eventually arrive around/after
sunset offering a low chance for spotty areas of light rain to crop
up late evening-early tonight.

Widespread showers arrive over SE MI early Saturday morning as the
aforementioned Ontario shortwave swings into the central Great
Lakes. Can`t rule out some rumbles of thunder or an isolated
embedded thunderstorm as showers work through during the morning due
to respectable forcing from the fairly robust parent vort max as
well as a few hundred J/kg of elevated instability. A dry slot
follows late morning/midday as the system undergoes occlusion
however this is shortlived as the near stacked low tracks directly
over the area Saturday afternoon favorably aligning with peak
diurnal heating. As a result, scattered to numerous showers with
isolated to scattered thunderstorms redevelop through the afternoon-
evening timeframe. Saturday looking to be the coolest day of the
forecast period as a reinforcing surge of Canadian air drops 850mb
temps to around 0C capping highs in the upper 50s to around 60,
though likely will feel cooler with the on-off rain through the day.

Northern edge of surface high pressure centered over the mid-
Mississippi river valley builds into southern lower MI Saturday
night-Sunday as upper troughing vacates toward the Northeast. Lower
level west-southwest return flow rapidly advects an above average
airmass (850mb temps climb to or above 10C) back into the region
likewise supporting above average highs in the upper 60s to mid 70s
Sunday and Monday. Active patterns continues early next week as
another upper trough drops into and lingers over the Great Lakes
offering additional chances for showers and thunderstorms.

MARINE...

Drier conditions expected today with just some lingering shower
activity possible this morning between Port Sanilac-western Lake
Erie. Brief period of high pressure today ensures light northerly
winds and minimal wave action. By Saturday, another glancing low
pressure system supports widespread showers across the area along
and behind a surface cold front. A shift to southwest winds ahead of
the front will be short-lived with the frontal passage veering winds
sharply back to the northwest by Saturday afternoon. High pressure
returns for Sunday ahead of yet another low to bring widespread
rainfall to the area on Monday. Wind and wave action hold below
headline thresholds through early next week.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

AVIATION.....BT
DISCUSSION...KDK
MARINE.......MV


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