Three Rivers, Michigan Weather Forecast Discussion

498
FXUS63 KIWX 302254
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
654 PM EDT Tue Sep 30 2025
.KEY MESSAGES...
- Slightly cooler temperatures for Wednesday and Thursday, but
  remaining well above normal.
- High temperatures rebound back into the lower to middle 80s for
  the weekend.
- Dry weather continues through the remainder of the week.
&&
.DISCUSSION...
Issued at 250 PM EDT Tue Sep 30 2025
Quiet weather conditions will continue through most of this
forecast period, with a potential of some increased rain
chances heading toward the Day 7 period.
An upper level trough digging across southeast Canada today will
continue to allow a backdoor low level baroclinic zone to sink
south/southwest across northeast CONUS/eastern Great Lakes into
early Wednesday morning. Fog potential is somewhat unclear
tonight as some drier air will be advecting via stronger
easterly flow across the eastern Great Lakes. Near term hi-res
ensemble guidance does offer some support for an increased fog
potential once again downwind of Lake Erie, just in advance of
the push of drier low level air. Patchy shallow ground fog will
be possible once again across most of the area Wednesday
morning, but will consider inclusion of fog in zone forecast
product for areas mainly along and south of US Route 24 given
above factors. Low level winds should be a bit stronger tonight
however, which may tend to limit fog potential.
Weak low level cold advection continues early Wednesday with this
pattern, and combination of these slightly cooler thermal profiles
and potential of some high clouds to spill over the ridge should
shave a few degrees off high temperatures for Wednesday (but still
well above normal for the beginning of October). Low level height
gradient will be slightly stronger for Wednesday which should
support some afternoon gusts into the 15 to 20 mph range. This
gustiness combined with lower dew points (min RHs 25-35
percent) advecting into the region Wednesday afternoon could
yield some low end fire weather concerns in terms of
grass/brush/field fires.
Low level thermal advection will be weak later in the day Wednesday
into early Thursday which should yield highs on Thursday similar to
that of Wednesday (generally in the mid 70s to lower 80s). The old
cut off upper trough across the southern Plains will get ingested
northward and will act to dampen mid/upper ridge toward the end of
the work week. Low level winds will veer to southwest as this
occurs, helping to advect in some warmer low level temps. Highs back
into the mid to even upper 80s appear likely for this weekend,
especially when considering dry ground and good amount of insolation
expected. Record highs for the weekend are in the upper 80s to
around 90.
Medium range guidance has been consistent in an upper wave
evolution of a northern stream trough ejecting across Upper
Midwest by Monday with a cut-off low developing across western
CONUS. Deterministic/ensemble solutions still show a wide range
of solutions regarding the finer details with the northern
stream wave evolution which will impact placement and southward
extent of low level baroclinic zone Monday/Monday night. Have
sided with ensemble mean idea of front displaced far enough
northwest during the day Monday to keep rain chances out of the
local area. Additional northwest flow wave should push
baroclinic zone across the area some time later
Tuesday/Wednesday with much cooler conditions expected toward
end of this forecast valid period, along with a chance of
frontally forced rain showers. Chances have been maintained on
the low side with still a question of how much moisture will be
available in advance of this potential cool front.
&&
.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 647 PM EDT Tue Sep 30 2025
Steady northeast wind tonight raises some concern for marine fog
to push well inland overnight. However, trajectories of this
possible fog bank vary. Given then uncertainty, will carry on
with the VFR TAFs at this time. Wind increases somewhat prior to
noon Wednesday.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Marsili
AVIATION...Brown

NWS IWX Office Area Forecast Discussion