022
FXUS63 KDTX 221658
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1258 PM EDT Wed May 22 2024

.KEY MESSAGES...

- A stray shower or rumble of thunder remain possible through mid
  afternoon.

- A brief warm-up is expected Friday with some additional chances
  for showers and storms Friday into Saturday.

&&

.AVIATION...

Late morning to early afternoon satellite and surface observations
clearly show the cold front position crossing southern Lower Mi.
Broken coverage of VFR cumulus is shown along and east of the front
with a stray shower or thunderstorm still possible, although a
shallow/capped appearance is noted at forecast issuance. Otherwise,
SW wind gusting around 30 knots exhibits a well mixed boundary layer
that is rapidly drying in model soundings through mid afternoon. The
pace of drying places the front east of the terminal corridor by 21Z
and closes the time window for a stray shower or thunderstorm.
Scattered VFR clouds to clear sky sets in this evening as peak wind
gusts taper off toward sunset and then around 20 knots as cooler air
continues flowing into southern Lower Mi this evening. Low to mid
level cool and dry air dominates late tonight as wind settles around
10 knots through Thursday morning.

For DTW/D21 Convection... Low probability for a stray shower or
thunderstorm until 21Z.

DTW THRESHOLD PROBABILITIES...

*  Low for thunderstorms through mid afternoon.

&&

.PREV DISCUSSION...
Issued at 354 AM EDT Wed May 22 2024

DISCUSSION...

A strong low pressure system now located over southwest Ontario will
occlude through the morning hours, taking on a more northeast
trajectory as it paths into the James Bay by this afternoon. This
will result in a cold front that is on track to traverse across
Michigan from west to east between the hours of 12Z to around 22Z.
Prior to the arrival of this frontal boundary, strong southwest flow
characterized by h850 wind speeds between 45-50 knots have sustained
overnight lows in the low to mid 70s, supported by the large
positive flux of warm air advection. It is safe to say these
overnight temperatures will easily break record high low temperature
values (see the climatology section). An isolated shower or storm
will be possible through the late morning and into the afternoon
along the instability gradient, but a building cap around 7kft and
inflow of drier air in the mid-levels will have a hampering effect on
greater convective potential. While the hi-res output is less than
impressive in regards to CI, the thermodynamic and kinematic profiles
do support a marginally severe environment with MLCAPEs hitting
1,500 J/kg and bulk shear values around 20-25 knots. In this low
probability setup (30-35 PoPs, favored along or east of a line from
Bad Axe to Adrian), there will be the low chance of a storm becoming
strong, with highly localized gusts to 50 mph and/or hail to an inch
as the main threats. The best window for this will be between
15Z-19Z.

Otherwise the improved mixing depths fueled by diurnal heating will
interact with the stronger winds aloft, bringing breezy conditions
through the day. Expect sustained 20 mph winds from the southwest
with gusts 30-35 mph. Clouds will clear in the wake of the front,
where a notable difference in humidity will be felt. Highs return
into the mid-70s (Tri-Cities) to lower 80s.

There will be a low chance for a shower late tonight as an upper-
level wave quickly moves over the state, but otherwise clear skies
and the early day passage of the cold front will work to drop
temperatures into the 50s. The Great Lakes will then be wedged in
the northern periphery of a high pressure system under increasingly
zonal mid-level flow through early Friday. Dry weather will persist
through Friday, with building temperatures back into the 80s on Fri
as an upper-level wave carves into the northern Plains, which will
reinforce ridging across the Great Lakes. An extension of this wave
will bring the chance for showers and storms on Saturday. High
pressure will quickly fill in behind this wave, where a second
chance of showers/storms then moves in Sunday/Monday. An upper-level
wave crossing near the Panhandle of Texas will strengthen low
pressure, which will then drive it northeast into the Midwest/Great
Lakes, becoming the source for the early week precipitation chances.

MARINE...

A strengthening low pressure system will reach western Lake Superior
this morning before lifting and stalling over Ontario. Meanwhile it
will force a cold front through the Great Lakes this afternoon.
There may be some scattered showers and thunderstorms ahead of the
front this morning with additional chances later this afternoon with
the front. Winds increase out of the south to around 20-25 knots
ahead of the front this morning, then veer to the west Wednesday
night into Thursday but settling back down to 15 knots. A small
craft advisory is in effect for Saginaw Bay this morning through
this evening as the winds funneling out of the bay have a higher
chance to exceed 25 knots.

CLIMATE...

Here are the record high temperatures for May 22:

May 22nd:
Detroit                90 (set in 1994)
Flint                  91 (set in 1934)
Saginaw/Tri-Cities     89 (set in 1992)

Here are the record high low temperatures for May 21-22:

May 22nd:
Detroit                67 (set in 1941)
Flint                  65 (set in 1977)
Saginaw/Tri-Cities     68 (set in 1977)

&&

.DTX WATCHES/WARNINGS/ADVISORIES...

MI...None.

Lake Huron...Small Craft Advisory until 10 PM EDT this evening for LHZ421-422-
     441.

Lake St Clair...None.

Michigan waters of Lake Erie...None.

&&

$$

AVIATION.....BT
DISCUSSION...AM
MARINE.......AM
CLIMATE......AM


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