007
FXUS63 KDTX 111631
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1231 PM 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.

&&

.AVIATION...

A broad area of weak high pressure will reside across Se Mi through
the rest of the day. This will maintain light winds through the TAF
period. The interaction of daytime heating on residual low level
moisture resulted in a SCT-BKN diurnal cu field. Bases have been
rising from MVFR to VFR with the growth of the daytime mixed layer.
Scattered to occasionally broken diurnal cu is expected to persist
through the afternoon before gradually mixing out and/or dissipating
late this afternoon/evening.

For DTW/D21 Convection...Weak instability this afternoon will keep
any convection isolated at best today.

DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 331 AM EDT Thu Jul 11 2024

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.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 4 PM EDT this afternoon for MIZ049-
     055-063.

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

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

$$

AVIATION.....SC
DISCUSSION...AM
MARINE.......KGK


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