732
FXUS63 KDTX 120752
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
352 AM EDT Fri Jul 12 2024

.KEY MESSAGES...

- Isolated showers and storms will expand across Southeastern
Michigan through the day. These storms are not expected to be
severe.

- There will be a few chances for thunderstorms later this weekend
and into next week. Severe weather will be possible with the systems
on Sunday and again Monday evening.

- A period of hot and humid conditions are forecasted for Sunday and
Monday with temperatures reaching near 90.

- Cooler weather will move in Tuesday through the rest of the week.

&&

.DISCUSSION...

Chances of showers and thunderstorms exist nearly daily today
through early next week as a hot and humid airmass builds over the
region. Forcing will be fairly weak most days with no significant
frontal passages til about Tuesday, but several mid level waves will
pass through a weak westerly/pseudo zonal flow pattern through the
weekend. There will be a couple chances for strong/severe storms
Sunday and Tuesday which we`ll get into below.

Surface high pressure will hold across the region today while a mid
level shortwave passes overhead. This wave is currently over
southern Lake MI but will drift across lower MI through the day and
into Ontario by tonight. There will be some mid level support for
showers and thunderstorms as lobes of vorticity and slightly cooler
mid level temps escort the wave eastward. Being on the west side of
the surface high will really put a damper on any organized storms
today with very little flow up to 600 mb and warm advection occuring
through the day. So most guidance advertises tall skinny cape with
20-30 knots with better cape (around 1000 J/kg) to the north by MBS
closer to the low center and around 500 J/kg south of PTK. This
morning the first lobe of vorticity will lift through the Detroit
area giving the first chance of showers and storms. With light winds
and high pressure at the surface, lake breezes will likely generate
which will offer continued activity into the afternoon along the
eastern counties. Second vort lobe will then swing through Mid MI
later in the afternoon. In addition, dewpoints will be in the mid
60s with over 1 inch of PWAT so with diurnal heating getting highs
into the 80s so we could generate some pop up diurnally forced
showers as well. With lack of stronger forcing, will keep a general
chance/scattered pop going today as cells could pop up anywhere.

Saturday looks pretty dry as mid level ridging slides overhead to go
along with the lingering surface ridge. Temperatures increase into
the mid/upper 80s as southwesterly winds at the surface and westerly
winds aloft both offer warm air advection. Dewpoints still holding
in the mid/upper 60s will make for a muggy day with heat indices
around 90 degrees.

Sunday through Tuesday brings several chances for thunderstorms as
strong ridge over the southwest conus hold firmly against several
northern stream troughs as jet level flow tops out only around 50
knots so no waves strong enough to dig into and displace the ridge.
This helps set up a low amplitude west-northwesterly flow pattern
across the Plains and into the Great Lakes. As this is setting up
though, a shortwave will lift northeast across the state line
bringing a chance of showers to the metro Detroit area Sunday
morning. Attention then turns to the potential for an MCS to develop
over MN and track E-SE across WI and into the Great Lakes. Many
models (GFS, NAM) keep it tracking more easterly across northern MI
clipping portions of Mid MI and the Thumb as a warm front sets up
across that area helping to steer it. The Euro and RRFS both offer a
more southern track with the RGEM somewhere in between. Will have to
wait and see where the MCS originates to see how far south it can
track with the westerly steering flow but we`ll keep a mention of
thunderstorms and potential for severe weather Sunday for this
feature.

Heat ridge folds into the region Sunday and Monday with 850mb temps
possibly exceeding 20C so highs of 90F will be possible both days.
Will need to watch cloud trends to see if we can reach these temps
as this pattern with all the moisture and upstream convective
systems may keep temps down. Strongest synoptic feature will arrive
Monday night into Tuesday as a trough finally gets some jet level
support with a strengthening cyclonically driven jet max helping to
push a cold front down through lower MI. After the storms clear,
Canadian high pressure will bring cooler temperatures into the
region for the rest of the week. 850mb temps look to hover around
10C keeping highs in the upper 70s to near 80.

&&

.MARINE...

A disorganized ridge of high pressure provides light winds out of
the south-southeast today as the diffuse system drifts toward the
Eastern Lakes. Winds/waves generally hold below criteria today and
through the weekend in the absence of stronger flow. One caveat
exists for marginal Small Craft Advisory gust potential amidst
southwest flow over Saginaw Bay as peak winds approach 25 knots
Sunday afternoon. A chance for isolated showers/storms exists this
afternoon before storms return with broader coverage Sunday and
Monday upon arrival of a warm front and approaching low pressure
from the west. Some stronger storms are possible both days which
could pose a heightened risk for locally higher winds/waves and hail.

&&

.PREV DISCUSSION...
Issued at 1113 PM EDT Thu Jul 11 2024

AVIATION...

VFR conditions will continue through the early morning hours as
light winds gradually settle out of the east-southeast. Diurnal
cumulus field develops today with a chance for scattered showers and
thunderstorms as an upper trough swings over Michigan. Models point
towards the metro terminals as the favored area for any activity that
develops, but there remains some uncertainty in overall coverage and
exact timing of activity. The late morning/early afternoon time
frame is the favored period for development. Outside of any showers
and thunderstorms will be prevailing VFR conditions that will carry
into tonight.

For DTW/D21 Convection...Scattered showers and thunderstorms will be
possible around the D21 airspace today. Confidence in location,
coverage, and exact timing remains low. The late morning/early
afternoon would be the favored period for any showers and
thunderstorms.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms today.


&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...None.
Lake St Clair...None.
Michigan waters of Lake Erie...None.
&&

$$

DISCUSSION...DRK
MARINE.......KGK
AVIATION.....AA


You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.