005
FXUS63 KDTX 110731
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
331 AM EDT Thu Jul 11 2024

.KEY MESSAGES...

- There will be a chance (20-30%) for showers or a thunderstorm
across the Tri-Cities this afternoon and evening.

- Isolated to scattered shower and thunderstorm chances (30-40%)
expand across all of SE MI tomorrow afternoon and evening.

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

&&

.DISCUSSION...

A diffuse high pressure system has built in across SE MI in the wake
of post-tropical system Beryl, which has resulted in generally clear
skies, outside of periodic stratus, and light winds. Sustained winds
speeds of 5-10 mph will help prevent sustainable fog development,
but cannot rule out some patchy development of fog just prior to
sunrise, mainly between 9-11Z. For this afternoon and evening, given
yesterday`s widespread rainfall across all of SE MI, including the
wide swath of 2-4+" that fell across the central portion of the cwa,
one would expect daytime heating (0-3 km lapse rates of 7C/km) to
support a healthy strato-cu deck through the later afternoon and
evening hours. Model guidance is more optimistic with cloud coverage,
but will be increasing cloud coverage to partly sunny until
satellite imagery proves lackluster. Communities within the lake
shadow near Lake Huron will have much higher chances to see sunny to
partly cloudy conditions Otherwise, any sort of instability will
reside over the the west-central side of the state, where weak
surface convergence will provide the chance for showers or a
thunderstorm. There is a chance this convergence extends into the
Tri-Cities, so a chance (30%) of showers or a storm will hold there.
Cannot rule out a stray shower along the lake breezes of Lake
Huron/St Clair/Erie, but this will not warrant PoP chances above
10%.

Friday will exhibit more favorable chances for showers and
thunderstorms once diurnal instability builds, increasing CAPE
values to around 1000 j/kg. An outflow from decaying showers and
storms over northern Indiana will provide the chance for showers
and storms in the afternoon and evening. An upper-level shortwave
also pivots right over SE MI through the afternoon, lending
increasing confidence for shower and storm chances. Outside of
modest instability, effective inflow layers are shallow and shear is
weak, so severe weather is not expected. Thunderstorms with periods
of heavy downpours will be the main threats.

Upper level flow turns more zonal this weekend through the middle of
the week. The bulk of Saturday will be supportive of dry weather
with diffuse high pressure still influencing the Great Lakes. A
series of upper-level shortwaves and an added boost in heat and
moisture derived from the central Plains under westerly flow will
increase rain and thunderstorm chances through the early and middle
part of next week. While it is too soon to pinpoint any widespread
or strong shower/storm potential, Sunday into Monday morning will a
window to watch for potential MCS systems that may filter in from
the Plains into the Great Lakes. Favorable H850 and H700 southwest
flow will help sustain heat and moisture across the Plains. The
zonal flow has the potential to direct any sustained thunderstorm
activity into the Great Lakes.

&&

.MARINE...

Winds decrease steadily today in the wake of Post-Tropical Cyclone
Beryl with northwest flow becoming weaker and westerly by this
afternoon. 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 likely into
next week.

&&

.PREV DISCUSSION...
Issued at 1220 AM EDT Thu Jul 11 2024

AVIATION...

The back edge of lower clouds are clearing Michigan to the east
leaving mostly clear skies during the overnight. The abundant surface
moisture and clearing skies brings potential for patchy fog to
develop early tonight. However, the limiting factor will be the winds
which should stay slightly elevated to around 5 knots out of the
northwest. Will introduce a minor drop in VSBY at TAF sites as some
sites across Michigan are already experiencing lower VSBYs. Early
morning trends will be monitored and will maintain VFR conditions for
now. Any patchy fog will lift with the sunrise as winds hold out of
the northwest through this morning and afternoon. Good surface
moisture will support a low VFR to possible MVFR diurnal cumulus
field this afternoon. Scattered showers and thunderstorms are also
late this afternoon, with the greater chances towards MBS. Winds
will become southwesterly during the evening will staying mostly
below 10 knots.

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

DTW THRESHOLD PROBABILITIES...

* Low for ceiling aob 5kft through early morning. Moderate this
  afternoon.

* Low for thunderstorms this afternoon.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through this afternoon for MIZ049-055-063.

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

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

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

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

&&

$$

DISCUSSION...AM
MARINE.......KGK
AVIATION.....AA


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