Saginaw, Michigan 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

759
FXUS63 KDTX 042330
AFDDTX

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

.KEY MESSAGES...

- There is a chance of showers and thunderstorms today with an
isolated risk for strong to severe storms through 10 PM.

- Additional chance for showers and embedded thunderstorms tonight
into 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 through Sunday.

- Heat and humidity remain to start the weekend but at more
manageable levels with highs in the mid 80s and heat indices in the
low to mid 90s today.

&&

.AVIATION...

Moist and weakly unstable conditions will maintain a lower
probability for a shower or thunderstorm to develop across southeast
Michigan thru the late evening period, although confidence in
occurrance remains quite low. Otherwise, lingering pockets of VFR
diurnal cu fade with the loss of daytime heating, leaving simply
thick cirrus heading into the overnight period. There remains some
potential for the ongoing convective activity upstream to ease
toward the region throughout the night. Latest model evidence
suggests a modest probability for showers containing isolated
embedded thunderstorms to arrive locally after 08z. Forecast will
continue to highlight the mid-late morning hours for possible tsra.
Notably greater potential will again focus Sunday afternoon as a mid
level trough lingers over the regin. High likelihood for
intervals of showers and thunderstorms during this time.

D21/DTW Convection...Cold front moving across DTW will bring a wind
shift to northeast around 00z and maintain a very low probability
for a shower or thunderstorm to develop prior to midnight.

.DTW THRESHOLD PROBABILITIES...

* Low in thunderstorms this evening through Sunday morning. Medium
  Sunday afternoon.

* Low in ceilings aob 5000 feet through Sunday morning

&&

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

$$

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


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