Saginaw, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

864
FXUS63 KDTX 050352
AFDDTX

Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1152 PM EDT Sat Jul 4 2026

.KEY MESSAGES...

- Chance for showers and embedded thunderstorms Sunday as a low
  pressure system drifts south of the state. There is an even lower
  chance for isolated strong to severe storms.

- There is a localized heavy rainfall threat Sunday.

&&

.AVIATION...

Prevailing northeast flow working into a very moist resident
environment will tend to favor some degree of low cloud and/or fog
formation early this morning. Latest observational trends offer some
support for the southward expansion of IFR to lower MVFR stratus
with time. Forecast will highlight a window for this stratus to
emerge locally prior to daybreak. Existing visibility restrictions
in haze encouraged by the earlier fireworks will likely linger to
some degree through the night given the weak flow. Notably greater
potential for shower and thunderstorm development will focus Sunday
afternoon as a mid level trough lingers over the region. High
likelihood for intervals of showers and thunderstorms during this
time, particulaly across the Detroit airspace.

D21/DTW Convection...Chance for thunderstorms exists Sunday
afternoon and early evening.

.DTW THRESHOLD PROBABILITIES...

* Medium in thunderstorms Sunday afternoon and early evening.

* Medium in ceilings aob 5000 feet at times tonight and Sunday
  morning. Low Sunday afternoon.

&&

.PREV DISCUSSION...
Issued at 322 PM EDT Sat Jul 4 2026

DISCUSSION...

Active holiday weekend is underway across SE Michigan as heat and
humidity fuel thunderstorm chances today and Sunday. Extended
stretch of above normal temperatures has generally come to an end
with temperatures now in the mid 80s, and even cooler high
temperatures (low 80s) Sunday through Tuesday as a weak cold front
drops across Lower Michigan rest of today and tonight. This occurs
as high pressure expands south into Ontario.

The front will be the main driver of scattered thunderstorm chances
this afternoon-evening. Have already seen activity light up along
the convergence axis, which will migrate south between now and
roughly 02z (10pm) tonight. The main limiting factor to convective
vigor is the marginal instability profiles, as mid-level lapse rates
are only about 5.0-5.5 C/km. That said, if the outflow from these
storms can constructively merge into an organized cold pool this
could offset some of the instability limitations. Latest thinking
from a severe standpoint is that these storms will be capable of
gusts 40-60 mph as they track south-southeast through the evening
hours. Will also need to keep an eye on the MCS that is developing
over northern Illinois. Models have shifted slightly, now hinting at
the MCS clipping into lower MI later tonight. If this occurs, still
looking at wind as the main threat but would mean higher PoPs
continuing across the south overnight.

The perturbation driving this feature is forecast to move across the
Ohio Valley late tonight, with several additional waves then
forecast to follow in its footsteps until the main trough axis
arrives Sunday afternoon. As this occurs, the mid level deformation
axis eventually forms into a closed low. All of these waves will be
capable of engaging the moisture-rich, unstable airmass to keep
showers and storms going overnight, particularly south of M-59. Much
of this will be ongoing upstream activity that advects into the
area, similar to what we have seen over the past 24 hours.

Arrival of the synoptic trough Sunday afternoon strengthens the
signal for an extended period of deformation over SE Michigan. Plan-
view wind plots show potential for a convergence axis to develop
over Ontario, which would be capable of sending multiple rounds of
slow-moving showers/storms into the Detroit Metro region Sunday.
This combined with the slow storm motion (~10 knots), a moisture-
rich environment (PWAT of at least 1.8 inches, dewpoints in the low
70s), and modest instability all point toward a heightened heavy
rainfall risk starting Sunday and ending when the deformation axis
pushes east. There will also be an isolated damaging wind threat due
to precipitation loaded cores. When this deformation axis dislodges
is inconsistent in the current model suite, ranging sometime between
Sunday night and Tuesday. This equates to a low predictability setup
for the early week period which could include persistent rain
chances. More details on the heavy rainfall threat in the Hydrology
section.

Cooler temperatures expected early next week, followed by another
heat spell mid-week as high pressure/upper level ridging build in.
NBM high temperatures once again approach 90 degrees, although SE
Michigan will be on the eastern periphery of the ridge which tends
to be more open to the storm track. This expecting an active late
week period.

MARINE...

Ongoing progression of a cold front which has now cleared the Saginaw
Bay and southern Lake Huron will continue to progress south this
evening across Lake St. Clair and Lake Erie. This will pivot wind
direction from the northeast and will bring the continued chance for
isolated/scattered showers or thunderstorms. Outside of any
thunderstorm development, ambient winds remain on the lighter side
this weekend and into early next week as high pressure system builds
in. Additional shower and thunderstorm chances exist again tomorrow
across the southern Great Lakes, but otherwise the early week period
will remain dry.

HYDROLOGY...

Several opportunities for showers and thunderstorms exist through
the holiday weekend within a favorable environment for heavy
rainfall. A swath of 1+ inch rainfall fell over the I-94 corridor
last night with half inch reports in many other locations. Any
additional storms that develop within this environment will be slow-
moving and capable of rainfall rates in excess of an inch per hour.
A heightened opportunity for heavy rainfall exists Sunday and Sunday
night with potential for a convergence axis to develop over Ontario
and establish a band of training showers and storms into the urban
areas of the Detroit Metro region. This could result in localized
storm totals in excess of 2 inches. Confidence in this type of
pattern however is low and the model signal is weak, but if this does
occur there is increased potential for flash flooding especially in
urban, low-lying, and flood prone areas.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Small Craft Advisory from 10 AM to 10 PM EDT Sunday for LHZ421-422.

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

$$

AVIATION.....MR
DISCUSSION...MV
MARINE.......AM
HYDROLOGY....MV

You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.