Nottawa, Michigan Weather Forecast Discussion

087
FXUS63 KIWX 210709
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
309 AM EDT Sun Sep 21 2025
.KEY MESSAGES...
- A wet period is ahead this entire upcoming week with numerous
  chances for showers.
- Isolated to scattered thunderstorms are possible most days.
- The best chance for marginally severe storms is Sunday with
  strong to possibly damaging winds the greatest threat.
&&
.DISCUSSION...
Issued at 107 PM EDT Sat Sep 20 2025
Scattered showers and an occasional isolated thunderstorm were
occurring west of Highway 31 and mainly west of a line from Eau
Claire to SBN to Monticello. Locally heavy rainfall of 1-2
inches had fallen earlier with showers and storms. The latest
HRRR indicates more activity should redevelop tonight after 01Z
(9pm EDT) west of Interstate 69. Severe weather is not expected
but locally heavy rainfall is possible.
The SPC has the entire forecast area in a Marginal severe storm
risk Sunday. More energy from the upper level trof should reach
northern Indiana and be accompanied by unidirectional flow at 20
to 30 knots with CAPE values < 800 J/Kg. The best chances for
any strong to severe storms favor 3pm EDT to 11pm EDT. Strong
to possibly damaging winds are the greatest threat.
A very active pattern is setting up that will persist through the
upcoming week. A negatively tilted upper level trof had developed
over the forecast area as energy from the Pacific had topped the
upstream ridge. Numerous impulses of energy throughout this upcoming
week will bring showers and scattered storms as this pattern
persists.  The latest WPC forecast indicates over 3 inches of rain
are expected through Friday night.
&&
.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 150 AM EDT Sun Sep 21 2025
A perturbed southwest upper flow pattern continues across the
Great Lakes/Ohio Valley regions early this morning. Some
scattered light showers continue across northern Indiana as of
0530Z in response to a few small scale vorts moving through this
flow along with a broad advective forcing regime. Another
convectively enhanced short wave across northern Illinois may
bring another round of scattered showers and perhaps an isolated
thunderstorm to the terminals in the 10Z-16Z timeframe. After
this time, may need to watch for the northeast advection of yet
another convectively enhanced short wave that will feed off
ongoing convection across southern Missouri early this morning.
This forcing is expected to lift northeast and likely augment
downstream southerly low level flow across central Indiana.
Greatest risk of thunder this cycle appears to be at KFWA in the
20Z-02Z timeframe as this convectively enhanced short wave
approaches and low level jet forcing/moisture convergence
increase and lift north into northeast Indiana. Some patchy fog
is possible this morning, particularly across KSBN vicinity
which received some light rainfall yesterday. Otherwise, VFR
conditions should prevail outside of any heavier showers/storms.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...MCD
AVIATION...Marsili

NWS IWX Office Area Forecast Discussion