Expert Forecast Opinion

801
FXUS63 KDTX 110850
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
450 AM EDT Mon May 11 2026

.KEY MESSAGES...

- Frost is likely again tonight.

- Numerous to widespread showers with a rumble of thunder move in
Tuesday afternoon and night.

- A warming trend carries temperatures above normal heading into
next weekend.

&&

.AVIATION...

SCT-BKN mid-level clouds (6-12 kft) persist today, remaining longest
over the southern TAF sites. Light northerly winds will maintain dry
low levels; however, flow off Lake Huron is expected to develop some
lower clouds this afternoon, especially over the southern terminals
(PTK/DTW/YIP/DET). These clouds should remain above 5000 feet. The
loss of daytime heating and high pressure overhead will lead to
clear skies and near-calm winds tonight.

D21/DTW Convection...No thunderstorms through TAF period.

.DTW THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 355 AM EDT Mon May 11 2026

DISCUSSION...

Great Lakes weather is strongly influenced by cool central Canadian
to Midwest high pressure that moves overhead this afternoon and then
drifts eastward tonight. The surface high makes a more aggressive
move into Lower Mi after the larger scale mid level trough moves
eastward. The catalyst for progression is the passage of a small but
intense mid level circulation that moves overhead this morning. This
system is tapping the low to mid level theta-e gradient associated
with the Ohio valley frontal remnants to bolster mid level cloud
production. A few sprinkles are also in play toward the Ohio border
during the morning while the clouds linger with enough coverage to
substantially delay the diurnal heating influence on temperatures.
Guidance max temps in the 50s look reasonable with the Tri Cities
down to I-69 having a chance to overachieve as sun breaks out
toward afternoon.

Tonight starts out with high pressure centered over Lower Mi and a
pronounced 500 mb short wave ridge in place just west of Lake Mi.
Confluent flow aloft forces deep subsidence across the central Great
Lakes leading to a higher confidence scenario for clear sky compared
to recent nights until cirrus arrives toward sunrise. The clear sky
and calm wind set up efficient radiational cooling and high
likelihood for another round of frost across the region except for
the immediate Detroit area.

Eastward departing high pressure and increasing clouds Tuesday
morning are signs the next low pressure system is on schedule to
bring showers in by afternoon. This system is still moving out of
the Canadian Rockies this morning, however there is good agreement
among the 00Z model runs that show the system benefiting from lee
side cyclogenesis and upstream longwave amplification today and
tonight. The strengthening process puts the system in good position
to accelerate northward transport of Gulf modified air into
isentropic ascent along and ahead of the low track. General thunder
is supported by 850 mb LI dropping to around 0C in weak elevated
instability across Lower Mi, ahead of the surface warm front still to
our west by 00Z Wednesday. The surface low and frontal system then
quickly move through the central Great Lakes Tuesday night while the
500 mb trough attempts to close off over southern Ontario. This trend
in the models is less progressive and maintains a cold core upper
trough/low influence over the central Great Lakes during Wednesday.
Mid May daytime heating then supports at least scattered showers over
SE Mi Wednesday afternoon and evening.

Despite the slower progression of the Wednesday system, the late
week is still a transition period for the larger scale mid to upper
level pattern. Extended range deterministic and ensemble systems
show good agreement on a solution that shows the mean flow shifting
from a high amplitude long wave trough over the Great Lakes and NE
States to more of a zonal configuration from coast to coast. The
height rises even into "just" a zonal flow add confidence to a
meaningful warming trend for the Great Lakes heading into the
weekend. A flip to above normal temperatures well into the 70s comes
at the expense of predictability on precipitation systems made
difficult by fast moving short waves within the larger scale zonal
flow.

MARINE...

High pressure influence holds over the region today and tonight
while maintaining light marine winds. Next low is set to sweep
across the Great Lakes late Tuesday bringing widespread showers and
a few chances for thunderstorms mainly over the southern Great
Lakes. In advance of the system, southerly winds strengthen though
with ongoing warm advection, thermal stability over the waters caps
peak gusts around 30kts. Moderate NNW winds follow Wednesday as
cooler air filters back in behind the low however a diminishing
gradient holds wind under 30kts. High pressure briefly follows to
close out the work week.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Frost Advisory until 7 AM EDT this morning for MIZ047>049-053>055-
060>063-068>070-075.

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

$$

AVIATION.....SF
DISCUSSION...BT
MARINE.......KDK


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