467
FXUS63 KDTX 031430
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1030 AM EDT Fri May 3 2024

.KEY MESSAGES...

- Morning showers and a few rumbles of thunder exit the area by early
  afternoon.

- A broken line of showers and sub-severe thunderstorms develops
  along a cold front that will track west to east across the area
  between roughly 2 PM and 8 PM this evening.

- High pressure fills in briefly on Saturday offering drier weather ahead
  of the next weak cold front that tracks through SE Michigan early
  Sunday morning.

- Seasonably warm temperatures expected through early next week with high
  temperatures in the low to mid 70s.

&&

.UPDATE...

Numerous showers and a few thunderstorms are ongoing across the cwa
this morning. Lightning observations so far have been rather
limited, but a few rumbles of thunder are still possible given
observed mid level lapse rates of 6.2 C/km and MUCAPE around 400
J/kg per the 12z KDTX RAOB. Individual storm motion has been SW to
NE at roughly 40 mph, while the broader precipitation shield has
been moving west to east and is on track to exit into Ontario by
early afternoon. Drier conditions thus arrive mid-day, and PoPs have
been adjusted accordingly to drop down to chance after between 16-
18z (noon-2pm local).

Upstream cold front then looks to reinitiate convective activity
this afternoon, with the front currently extending from South Bend to
Cheboygan. Timing of the front and associated shower/thunderstorm
chances begin in the Tri Cities around 18z (2pm) with a gradual drift
eastward toward Detroit by around 00z (8pm). No changes to expected
intensity with storms expected to hold below severe limits.
Thunderstorms may dissipated before reaching eastern counties of the
cwa with the front expected to wash out overhead, and instability
waning as diurnal heating ramps down this evening.

&&

.PREV DISCUSSION...
Issued at 631 AM EDT Fri May 3 2024

AVIATION...

Upper level short wave energy, weak elevated instability and deep
layer moisture advection along/in advance of surface low pressure
and a warm front will sustain areas of showers this morning. Waning
elevated instability will limit the risk of additional thunderstorms
this morning. Area observations continue to support VFR ceilings for
at least the next two to three hours. Continued influx of low level
moisture along with the ongoing rain will result in increased chances
for MVFR based ceilings after 15Z. A decrease in the overall
coverage of showers is expected in the 15 to 18Z time frame. This
will open the door to some weak diurnal destabilization, supportive
of a chance of thunderstorms (mainly across Metro Detroit) late this
afternoon and evening. The sfc low and cold front will progress from
northwest to southeast across the forecast area between 19Z and 00Z,
leading to a post frontal wind shift to the NNE along with some
improvement in ceilings.

For DTW/D21 Convection...Additional chances for thunderstorms across
the airspace will be more or less isolated, less than 20 percent,
this morning as elevated instability wanes. Convective redevelopment
is forecast this afternoon along a cold front. A scattered line of
showers and thunderstorms is forecast to traverse the airspace
between 21Z and 01Z.

DTW THRESHOLD PROBABILITIES...

* Low for thunderstorms today.

* Moderate for ceiling 5000 ft or less this afternoon and tonight.

PREV DISCUSSION...
Issued at 320 AM EDT Fri May 3 2024

DISCUSSION...

Large upper level low/trough over Central North American early this
morning, with the center along the northern Minnesota border. The
500 MB low (~540 DAM) will track off to the northeast, reaching
Hudson Bay Saturday morning.

Deep southwest flow will maintain above normal temperatures over
southeast Michigan right through the weekend. Moisture advection has
peaked out with the broad 850-700 MB Theta-E ridge axis extending
north, through the Central Great Lakes. Still looks like lingering
showers around today with possible thunderstorms as a ribbon of
upper level PV approaches from the southwest.  Severe weather not
expected with weak mid level lapse rates and MLcapes under 750 J/kg.

Height rises/surface ridging expected on Saturday, leading to mainly
dry conditions during the day. Low clouds trapped underneath
subsidence inversion, with perhaps a bit of drizzle/very light
showers toward the southern Michigan border where the higher dew pts
reside. Weak height falls/cold front then on track to move through
through Saturday night, worthy of chance pops, despite the bulk of
the forcing over northern Great Lakes.

Western confluent upper level flow Sunday preceding an upper level
ridge axis arriving early next week, supporting at least a 48 hour
window of dry and pleasant weather.

MARINE...

A low pressure system will then track through the northern Great
Lakes today pulling the warm front up through the region early in
the day. This will allow winds to flip around to the south-southwest
which will bring in a warmer airmass, helping to keep gusts down.
Scattered showers and thunderstorms will focus on this morning warm
frontal passage and may persist into the afternoon. Showers and
thunderstorms then increase coverage once again in the evening as
the cold front gets pulled through the region. Brief area of high
pressure brings quieter weather on Saturday. Winds will flip around
to the northeast behind the cold front tonight, but the area of high
pressure will keep winds below 20 knots. Southerly winds will
redevelop Saturday night ahead of the next cold front that will
sweep through Sunday, but will turn northwesterly behind the front
Sunday afternoon.

&&

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

$$

UPDATE.......MV
AVIATION.....SC
DISCUSSION...SF
MARINE.......DRK


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