561
FXUS63 KDTX 281800
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
200 PM EDT Tue May 28 2024

.KEY MESSAGES...

- Additional showers and thunderstorms are expected today with a
  few strong storms capable of small hail and locally gusty winds.

- Scattered showers and a few thunderstorms will linger tonight into
  Wednesday before drier conditions return to finish the work week.

- Temperatures will be below average throughout the midweek period
  before warming up again into the weekend.

&&

.AVIATION...

Diurnally aided scattered to numerous shower with embedded
thunderstorms are expected through the afternoon and evening.
Coverage is expected to increase through the afternoon, with most
favorable timing for any thunderstorm activity expected between 20Z-
01Z. Hi-res guidance highlights KDET and northwest through KMBS as
the more favorable locations to see thunderstorms, where the better
clearing has been observed. However, all metro terminals will be
susceptible to thunderstorms, just with higher confidence favored
across the northern airspace. Severe thunderstorms are not expected,
but small hail and gusts to 30 knots will be possible with the
stronger activity. Coverage will start to wane after sunset with the
loss of diurnal heating.

For DTW/D21 Convection...There continues to be a chance to see
scattered to numerous thunderstorms this afternoon and evening,
favored between the hours of 20Z to 01Z. The better coverage is
expected just north and east of the terminal, especially up towards
KPTK, but thunderstorms may develop in the vicinity of or over KDTW.
A VCTS group has been introduced given the increasing confidence,
and a short-fused amendment may be needed if observations/satellite
support a southern shift in projected thunderstorm development.

DTW THRESHOLD PROBABILITIES...

* Moderate in ceilings aob 5000 feet through tonight.

* Low for thunder this afternoon between 20-01Z.

&&

.PREV DISCUSSION...
Issued at 1123 AM EDT Tue May 28 2024

UPDATE...

Morning observational trends fully support the going likely/numerous
POP forecast for a flare-up of showers and storms this afternoon.
Late morning satellite imagery indicates open sky across the Tri
Cities and northern Thumb where rapid surface heating will occur
into early afternoon and where initial convective development is
likely. Even farther south there is adequate breaks in mid level
clouds for building surface based instability. Hi-res/rapid update
models look good offering an early afternoon shower/storm initiation
as forecast soundings show an uncapped thermal profile and a deep
moisture supply with PW hovering around 1 inch. The soundings also
indicate a weak wind profile favoring standard single cell pulse
mode as HREF mean MUCAPE hovers below 1000 J/kg within the
relatively cool boundary layer air mass. The earlier noted low
freezing level is verified near 8 kft in the 12Z DTX sounding and is
forecast to hold around that level this afternoon and evening. This
combined with low CAPE density updraft profiles favor brief periods
of pea size hail in isolated stronger storms. Localized heavy
rainfall and associated gusty wind are also possible but with low
predictability on location or duration given the random nature of
outflow driven redevelopment expected during late afternoon through
early this evening.

PREV DISCUSSION...
Issued at 310 AM EDT Tue May 28 2024

DISCUSSION...

Showers associated with an upper level shortwave will linger over
parts of the area this morning. However, better coverage for showers
and some thunderstorms will hold off until the maximum instability
peak this afternoon/early evening as leading edge of mid/upper level
cold pool (H5 temps -20C) associated with expanding upper troughing
filter over the area during peak heating. During this time frame, a
larger scale upper level system now dropping southeast through the
upper midwest will encroach on the region and aid in this convective
development to some degree.

HiRes models suggest SB/MU CAPES will top 1000 J/kg in pockets later
today as temperatures warm to near 70F under this increasingly cold
mid/upper level pocket of air. This seems reasonable and while this
is relatively marginal instability for widespread thunder, suspect it
will be enough to support updrafts capable of supporting small hail
development (especially given the freezing level somewhere around
8000 feet). Locally gusty small scale outflow wind gusts will also
be favored in this environment (perhaps on the order of 30-40 mph in
a few instances).

The aforementioned upper midwest shortwave will continue its trek
into the region tonight into early Wednesday and despite the loss of
daytime heating should support some continuation of showers and a
storm or two into tonight with a brief flare up of convection early
to midday Wednesday before forcing from this system settles south
of the forecast area. Thereafter, high pressure will build into the
region and provide dry conditions through Friday.

This high pressure will bring a period of notably cooler air to the
region through the middle of the week with maximum temperatures in
the 60s to near 70 Wednesday/Thursday while minimum temperatures
drop well into the 40s (and most likely upper 30s in a few rural
spots prone to strong radiational cooling).

Temperatures then warm back up late this week into the weekend as an
upper level ridge translates through the area in the wake of the
current upper troughing as it pivots east and northeast out of the
area. While this upper ridge progresses through the area quickly in
the late Thursday to Friday time frame, a more or less zonal upper
level flow pattern will then set up into the weekend and maintain a
return to 70s and eventually lower 80s for high temperatures by late
this weekend/early next week. A series of Pacific shortwave will
translate quickly through this west to east flow regime and bring at
least periodic chances of scattered showers/thunderstorm by the end
of the forecast (Saturday and beyond). Timing these "episodes" is a
fool`s errand at this point in the forecast.

MARINE...

Broad troughing aloft combines with an expansive surface pressure
gradient this morning to support sustained westerly winds of 15 to
20 knots. Meanwhile, a series of embedded shortwaves migrate through
the Great Lakes to support shower chances for most of the day with
thunderstorm potential increasing in the afternoon. Wind gusts to 25
knots persist through the afternoon before subsiding this evening as
the low is displaced further east and high pressure builds in from
Canada. Rain chances however will linger through the first half of
Wednesday with the upper trough axis finally swinging through mid-
day to bring in drier conditions. As the transition to high pressure
begins, winds become northerly with onshore flow building wave
heights toward Small Craft Advisory thresholds Wednesday afternoon
with quieter weather prevailing for late week.

HYDROLOGY...

Periodic scattered showers and thunderstorms will impact the region
into tonight and early Wednesday. Additional rainfall will generally
remain light to occasionally moderate with basin average rainfall
in the one quarter to one third inch range over the next 36 hours.
However, a few of the thunderstorms will likely bring locally heavy
downpours, especially during the afternoon to early evening period.
In these locations, minor flooding or ponding of water of roadways
can be expected.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory until 4 PM EDT this afternoon for LHZ421-422-
     441.

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

$$

AVIATION.....AM
UPDATE.......BT
DISCUSSION...DG
MARINE.......MV
HYDROLOGY....DG


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