Expert Forecast Opinion

037
FXUS63 KDTX 052303
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
703 PM EDT Tue May 5 2026

.KEY MESSAGES...

- Much cooler temperatures and periodic shower chances rest of today
through Friday.

- Temperatures drop into the mid-30s Thursday morning, possibly
leading to frost development.

- Warmer this weekend with continued rain chances.

&&

.AVIATION...

Maintenance of dry low level conditions ensures VFR through the taf
period. Expansive area of mid level cloud will persist north of a
frontal boundary tonight. Radar trends support latest model guidance
in maintain a higher probability of rainfall south of the region.
Forecast will continue to highlight a period of clearing Wednesday
morning. High based diurnal cu development and expansion for the
afternoon and early evening period. Prevailing winds from the west
to northwest.

D21/DTW Convection...No thunderstorms expected through Thursday.

.DTW THRESHOLD PROBABILITIES...

* None

&&

.PREV DISCUSSION...
Issued at 328 PM EDT Tue May 5 2026

DISCUSSION...

Broad longwave troughing governs the forecast over the next 7 days,
supporting a showery pattern and below normal temperatures through
the end of the work week. First instance of this is ongoing as the
elevated remnants of a frontal zone slowly exit SE Michigan. Quicker
pace of the front has displaced the highest rain chances to our south
and east compared to previous forecasts, although a second wave of
moisture over western Illinois may clip southern portions of the
forecast area later this evening. This keeps rain chances going
through late tonight for locations south of I-96. Cloud cover
diminishes toward northern Lower Michigan away from the frontal zone,
with the Saginaw Valley/Thumb on the northern fringe of the cloud
shield. This has implications for radiative cooling overnight, as
lows drop into the upper 30s to low 40s under a blanket of high
cloud. If cloud cover can clear entirely, some areas may see patchy
frost development (most likely for northern portions of Midland/Bay),
but confidence is low in this outcome.

Thermal trough settles into the Great Lakes region Wednesday-Friday,
drawing a pool of -5 to -10 C 850mb temperatures overhead. This
leads to a period of below normal temperatures with daytime highs
only reaching the upper 50s. Coldest temperatures are forecast to be
Thursday morning (mid-30s) as the base of the trough coincides with
the diurnal minimum and clearing skies. Frost/Freeze headlines will
be considered in subsequent forecast updates. This period will also
be characterized by multiple embedded shortwaves pivoting around the
Hudson Bay upper low. Diffluent northwest flow initially keeps
conditions dry Wednesday, even amidst synoptic ascent as one such
wave glances across northern Lower Michigan and the left exit of a
155 knot jet streak surges in from the south. A stray shower cannot
entirely be ruled out invof the vort max, but overall 5.0-18.0 kft
agl dry layer should be sufficient in preventing widespread shower
development. Combination of cold advection and the next embedded wave
Thursday lead to steepening low level lapse rates (sfc-3km lapse
rates exceed 7.0 C/km) and moistening mid levels to increase
convective shower chances Thursday afternoon-evening. This wave train
pattern continues Friday into the weekend, carrying periodic rain
chances through the remainder of the forecast period.

The overall precipitation pattern offers low predictability given
weak/transient forcing, disjointed moisture quality, and synoptic
scale wave interactions. There is model signal for a cold front to
track across the area sometime Saturday-Saturday night, which would
provide a more focused opportunity for shower and thunderstorm
chances. Depending on the timing of this front, temperatures could
warm well into the 60s Saturday in the presence of warm and breezy
warm sector flow. Ensemble members however still exhibit quite a bit
of variance in both timing/placement of the forcing this weekend
with a lot of details to work out before then.

MARINE...

A cold front is clearing the Central Great Lakes this evening, with
cold air advection gradually filtering through over the next couple
of days. Because the main low and tightest pressure gradient will
reside near or over Hudson Bay, winds are expected to stay mostly on
the light side (under 20 knots) for the rest of the work week. This
pattern of clipper systems bringing periodic chances for showers
will continue into the weekend as milder air and higher moisture
levels arrive. As it stands now, this leads to Saturday night being
the primary window for showers and isolated thunderstorms as a cold
front slowly moves through the region.

&&

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

$$

AVIATION.....MR
DISCUSSION...MV
MARINE.......SF

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at www.weather.gov/detroit.