853
FXUS63 KDTX 311104
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
704 AM EDT Fri May 31 2024

.KEY MESSAGES...

- Dry weather continues today and most of Saturday with a gradual
warming trend through the weekend.

- The next chance of rain arrives Saturday evening through Sunday
morning. There is potential for heavy rainfall with this system,
please refer to the Hydrology section for details.

- The weekend finishes dry and warm Sunday with highs near 80.

&&

.AVIATION...

A center of deep atmospheric high pressure will remain parked over
the central Great Lakes today. Dry air will limit much in the way of
cloud development.  Weak southerly winds of 5 to 10 mph are
anticipated.

For DTW/D21 Convection...Thunderstorms are not expected during this
forecast period.

DTW THRESHOLD PROBABILITIES...

* None.

&&

.PREV DISCUSSION...
Issued at 427 AM EDT Fri May 31 2024

DISCUSSION...

Another chilly start to the morning today with current temperatures
10 degrees below normal for late May. Temperatures quickly rebound
after sunrise however under full solar insolation and a departing
thermal trough. 00z KDTX RAOB recorded a deep layer of static
stability, maximized between about 6.0-10.0 kft agl, which will
persist through today as ridge amplification builds mid-level
heights to 582 dam. This ensures dry conditions that continue
through the first half of Saturday. Overnight lows moderate some ten
degrees compared to this morning as column winds organize out of the
southwest amidst modest warm advection.

CONUS-centered satellite imagery highlights two distinct systems
that will interact to create the next opportunity for rain late
Saturday into Sunday for southeast Michigan. The southern stream
wave lifts into the Ohio Valley by mid-Saturday, initiating a period
of strong low level theta-e advection on the cusp of a ~30 knot low
level jet. Cloud cover thus will be on the increase throughout the
day, although rain holds off until 21z (5pm) or later as ambient dry
low levels rely on the theta-e push to fully saturate. Moisture
quality will be excellent with this system with PWAT forecast to
rise above 1.5", which is in the 90th percentile for this time of
year. Freezing levels between 10.0-12.0 kft agl accompany deep
column moisture, favoring warm rain processes. These favorable
thermodynamics raise concern for heavy rainfall Saturday night-
Sunday morning.

From a forcing perspective, strong theta-e advection and eventual
release of the disturbance overhead provide a large footprint of
synoptic forcing and thus widespread rainfall across southeast MI.
Model QPF from synoptic forcing alone falls around a half inch or
less, but the heavy rainfall concern comes from the potential for
mesoscale banding to occur as the weakening northern stream trough
and southern stream wave interact over the Midwest. 00z guidance
struggled to agree on the strength, placement, and duration of any
mesoscale forcing mechanisms, likely due to differences in the
strength of the northern stream convergence axis and whether the
southern stream wave stays closed or opens up before reaching lower
MI. More details should become apparent as we get further into the
hi-res window today, but the main message at this point is a
conditional chance for heavy rainfall to exceed one inch Saturday
night-Sunday morning.

Rain comes to an end mid-day Sunday as high pressure fills in
briefly. Continued southwest flow offers warmer temperatures in the
80s by early next week with the next round of precipitation moving
in late Monday-Tuesday.

MARINE...

High pressure continues to govern local conditions today as it
drifts over southern Ontario. Winds shift to the south as a result
though hold sub 20kts across the region. High vacates early Saturday
as low pressure lifting into northern Ontario drags a cold front
into the Great Lakes. A secondary area of low pressure develops
along this boundary over the Ohio Valley before tracking into the
central/southern Great Lakes latter part of the day Saturday into
early Sunday. System brings mainly showers though a thunderstorm or
two will be possible over the southern Great Lakes. Weak high
pressure then briefly builds in late Sunday and Monday.

HYDROLOGY...

Showers move into SE Michigan Saturday evening with heavy rainfall
possible overnight as a deep supply of Gulf moisture lifts into the
region. While the broader footprint of forecast rainfall amounts is
around a half inch, there is potential for localized totals to
approach 1 inch or greater. There has been a slight slowing trend to
the system, but still looks progressive enough to prevent more
excessive totals with minor flooding of urban and low-lying areas,
ponding of water on roads, and rises in area rivers being the main
impacts.

&&

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

$$

AVIATION.....CB
DISCUSSION...MV
MARINE.......KDK
HYDROLOGY....MV/BT


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