479
FXUS63 KIWX 070031
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
831 PM EDT Mon Oct 6 2025

.KEY MESSAGES...

- Chances of rain will increase later this evening, with
  greatest coverage expected overnight tonight into Tuesday
  morning. A few thunderstorms will be possible tonight and
  Tuesday, but severe weather is not expected.

- Highest confidence in rainfall amounts between one quarter of
  an inch to one half inch is across far NW Indiana into SW
  Lower Michigan and also south of US Route 24 across northeast
  Indiana and northwest Ohio.

- Dry weather returns Wednesday and Thursday with a return of
  seasonable temperatures. Lows may dip into the 30s each night
  with patchy frost possible.

&&

.DISCUSSION...
Issued at 300 PM EDT Mon Oct 6 2025

Increasing rain chances for tonight and early Tuesday along with
cooler temperatures will continue to be the main forecast issues for
the short term. A weak low level jet from the Ohio River Valley will
continue to provide northward migration of moderate to strong low
level moisture transport into northeast Indiana and northwest Ohio
this evening. Pre-frontal confluence will aid in this northward
moisture transport but veering low level winds overnight will likely
keep deeper moisture profiles shunted across far southeast locations
or just southeast of the local area into southern Indiana and
central/southern Ohio. A second area of forcing will be tied to
southeast sagging low level cool front which is currently situated
from west central Illinois into south central Wisconsin. Overall
synoptic setup still appears to favor upper level jet largely
parallel to main baroclinic zone which is favoring anafront-like
characteristic to much of the shower activity being post-
surface frontal from central Iowa into Central Wisconsin. Well
to the southeast of this surface front across the local area, cu
field has rapidly expanded this afternoon with some vertical
extent in some of the better cu banding. An axis of low level
moisture convergence at the nose of the better southerly flow
impinging on the area could result in isolated-scattered shower
(possible thunderstorm) development through early evening,
although would expect rainfall amounts will be quite light.

The bulk of the rainfall activity still appears to be in store for
from late evening through early Tuesday morning. The idea of two
regions of maximum rainfall still appears reasonable for tonight
into early Tuesday. One area may be across the far northwest where
post-sfc frontal low level fgen forcing may be maximized late
tonight before low level convergence weakens some during the
day Tuesday as the front drops southeast. A second area may be
tied more to the pre-frontal low level confluence in association
with stronger low level jet and more anomalous deep moisture.
However, it is possible the bulk of the heavier rainfall will
stay south/southeast of the local area. A few isolated storms
are possible this evening and overnight, with some weak sfc
based CAPE on the order of 500-750 J/kg possibly promoting
additional isolated-scattered thunderstorm activity on Tuesday
mainly along/south of US Route 24 corridor. Rainfall amounts
with these two areas of more distinct forcing/moisture could
still reach the 0.25-0.50" range with a good possibility that
much of the forecast area between these two regions would
experience lesser amounts. Some localized heavier amounts are
possible across the southeast if some convective elements can be
realized.

Conditions dry out for Tuesday night with expansive Great Lakes
anticyclone allowing southward advection of much drier low level
air. Low level thermal profiles and placement of ridge axis could
support some patchy frost both Wednesday night and Thursday night as
low level thermal trough will be slow to weaken. Medium range
guidance continues to point to a more stable upper wave pattern
developing toward next weekend with next upstream longwave
ridge very slow to push east. Confidence is on the high side in
eventual moderation in temperatures by next weekend or early
next week, but timing of this moderation and extent still a bit
in question. Any additional precip chances for weekend/early
next week appear minimal and light in nature with moisture
availability limitations.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 744 PM EDT Mon Oct 6 2025

In the short term VFR conditions are in place. However, a cold
front currently moving slowly southeastward through northern IL
will begin to move into northern IN and current radar imagery
shows some scattered showers and thunderstorms popping up along
the boundary. These will begin to move into KSBN area after 02z
Tue. This boundary will bring cigs a bit lower. MVFR vsbys
possible with the heavier showers after 04z for KSBN.

At the same time to our south a moisture influx is moving
northward across central IN and will continue to spread into
northern IN. This is currently bringing light shower activity
into KFWA area. After 04z, MVFR cigs are expected at KFWA site.

As this front moves through and in the fronts wake overnight it
is expected that CIGs will drop even lower to IFR categories for
both sites after 07-08z Tue. Confidence is not high on dropping
into LIFR levels but isolated cigs below IFR would not be out of
the question. Improvements to cigs look to occur after 17z Tue
with drier and cooler airmass pushing in behind the frontal
boundary.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory from 8 AM Tuesday to 5 AM EDT Wednesday
     for LMZ043-046.

&&

$$

DISCUSSION...Marsili
AVIATION...Andersen