405
FXUS63 KDTX 110014
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
814 PM EDT Wed Jul 10 2024

.KEY MESSAGES...

- Rain diminishes to scattered light showers after midnight into
Thursday morning.

- Scattered showers and thunderstorms redevelop during the afternoon
both Thursday and Friday.

- A period of above average temperatures begins this weekend into
early next week.

&&

.AVIATION...

Lingering showers remain this evening as the remnants of Beryl
continue to push east. North to northwest winds will be gusty to
around 20 knots through much of the night as MVFR ceilings also
linger. There is some improving conditions across central Michigan
this evening and this will continue to spread southward through the
early morning hours bringing VFR conditions. Mid to high clouds
continue to clear out tomorrow morning with a low VFR to possible
MVFR diurnal cu field expected to develop by tomorrow afternoon.
Winds will hold out of the north to northwest to around 10 knots into
the early afternoon.

For DTW/D21 Convection...Scattered thunderstorms will be possible
tomorrow afternoon, but current thinking is that that best chances
will hold west of DTW.

DTW THRESHOLD PROBABILITIES...

* High for ceiling aob 5kft tonight.

&&

.PREV DISCUSSION...
Issued at 405 PM EDT Wed Jul 10 2024

DISCUSSION...

Mid afternoon observations and model analysis fields indicate near
surface based convection in the Detroit metro area has exited into
Ontario with the surface low remains of Beryl. That leaves the bulk
of deformation forcing to occur across the Thumb region for the
remainder of this event. Radar derived rainfall estimates and
surface reports show the heaviest rain has fallen along and west of
a line from Ann Arbor to Pontiac to Lapeer, including the Flint
metro area where cumulative rainfall from yesterday and today has
led to pockets of residential flooding. The Tri Cities and Thumb
regions meanwhile have been largely spared from excessive rainfall
with reports generally less than 1 inch since midnight. Model
consensus QPF that is now primarily east of the Tri Cities allows
cancellation of the Flood Watch there while continuing for the Thumb
region for up to 1 inch of additional rainfall through 8 PM.

Northerly wind gusting in the 30 mph range is the first sign of the
surface low associated with Beryl exiting into Ontario during late
afternoon and this evening. The other is showers gradually
diminishing around the western fringe of the system`s moisture field
while surface based convection holds across northern and western
Lower MI. Beryl moisture strips away later tonight, especially after
midnight, leaving just low clouds in place despite northerly wind
bringing in a cooler and less humid air mass into Thursday morning.

A smaller scale mid level circulation over the Midwest this
afternoon has northern stream origins from central Canada. It is
unrelated to Beryl but follows closely behind across the Great Lakes
during Thursday until nearly stalling overhead Thursday night into
Friday. This system has a cold core scattered convective appearance
in observations today which projects well to hold into Lower MI
Thursday afternoon and evening. Peak daytime instability generates
surface based CAPE across Lower MI but is projected to remain below
1000 J/kg in the 12Z HREF run, in line with the general thunder
convective outlook. Storm intensity diminishes to showers Thursday
evening and then coverage becomes isolated after midnight under the
lingering mid level circulation. Trends in today`s 12Z model package
slows the exit of this system into Friday afternoon requiring at
least an isolated shower/storm mention in the forecast.

Global/extended model runs offer mostly zonal solutions on the
larger scale mid to upper level flow pattern this weekend. The zonal
flow keeps predictability on the low side for shower/storm activity
but with a steady warming trend indicated in the data through
Sunday.

MARINE...

Post-Tropical Cyclone Beryl (or the remnants thereof) stream through
the central Great Lakes this evening fueling additional gusty
showers as the low tracks across the Ontario Peninsula. An uptick in
gradient wind is underway given the vicinity of the low pressure
center and strengthening of the surface pressure gradient.
Expectation for evening winds features a backing trend with time
while gustiness increases due to slightly steeper low-level lapse
rates augmented by the approach of a strong cyclonic lower column
wind field. Latest observations suggest additional isolated gusts to
gales may persist across portions of the Lake Huron nearshores, but
the general infrequency precludes an upgrade to Gale Warnings. Gusts
to around 30 knots will be more representative of prevailing
conditions through the evening hours. Further south, gradient winds
veer toward the northwest across Lake St. Clair and Lake Erie
producing Small Craft Advisory winds this evening, therefore the
current headlines will remain in effect. Winds decrease steadily
late tonight and into Thursday with northwest flow becoming weaker
and westerly by the afternoon hours. High pressure attempts to build
into the region Thursday and Friday while weak troughing may produce
some additional showers. Winds/waves hold below criteria through
Saturday and probably through the weekend time-frame.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 10 PM EDT this evening for MIZ049-055-
     063.

Lake Huron...Small Craft Advisory until 10 AM EDT Thursday for LHZ421-422.

     Small Craft Advisory until 4 PM EDT Thursday for LHZ441>443.

Lake St Clair...Small Craft Advisory until 10 AM EDT Thursday for LCZ460.

Michigan waters of Lake Erie...Small Craft Advisory until 10 AM EDT Thursday for LEZ444.

&&

$$

AVIATION.....AA
DISCUSSION...BT
MARINE.......KGK


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