569
FXUS63 KIWX 021023
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
623 AM EDT Thu Oct 2 2025

.KEY MESSAGES...

- Dry weather continues through the weekend.

- High temperatures rebound back into the lower to middle 80s
  for the weekend.

- Chances for light rain increase between Monday and Wednesday.

&&

.DISCUSSION...
Issued at 254 AM EDT Thu Oct 2 2025

A backdoor cold front pushed into the area over the last couple of
days by a southward moving Canadian high pressure system washes out
overhead. This front brought plenty of dry air as well as cooler
temperatures. The advancement of 70 degree high temperatures from
the northeast overtook the 80 degree highs yesterday and that`s the
story for today as plenty of upper 70 degree highs are expected
north of US-30. 80 degree highs look more prevalent south of US-30.
Dew points in the 40s and 50s will be common and this will create a
MinRH map with a majority of 30s and a smattering 20 percent values.
Some wind gusts were observed yesterday as a strong gradient paired
with mixing to allow for 20 to 25 mph gusts. Now behind that
backdoor front and with it washed out for today, a relaxed gradient
results and winds should be weaker today. So, while some grass/field
fires will be possible today given dry fuels, the relaxed winds may
limit erratic fire behavior to allow them to be controlled
easier.

What changes for Friday is the surface high pressure is able to sink
farther southward to be more to our east as opposed to our
northeast. This allows for more southwesterly wind trajectories and
greater warm air advection. As such, highs will be securely back
into the 80s with mid to upper 80s forecast. At the same time, dew
points will be able moisten back into the 50s to offset that
warming. Still MinRH values in the 30s of percentages will be
possible and can`t rule out some sporadic 20 percent values. Once
again, though, weak winds should limit fire activity.

It is interesting to see models print out some precipitation Friday
night across the area in conjunction with the arrival of moisture
and weak vorticity. The NAM is the main model that doesn`t shunt the
arrival of the 60 degree dew points just to our west like the low-
res models do. If memory serves, this battle occurred a month ago
and the NAM depiction actually proved correct in that the light rain
did push into the area despite the antecedent dryness. Cannot
necessarily bank on it happening so it won`t make the forecast, but
it is not outside of the realm of possibility to end up with a light
sprinkle west of IN-15 Friday night.

Otherwise, the weekend looks predominantly dry within the warm
advection pattern as ridging and surface high pressure suppress
rain. We`ll continue with the mid to upper 80 degree high
temperatures and the 50 degree dew points (perhaps some 60 degree
dew points in western areas on Saturday and some 40 degree dew
points in eastern areas on Sunday). The main thing that raises
eyebrows a little is the increased wind for Sunday. The pressure
gradient increases as a cold front begins to approach from the west
and surface high pressure continues to drop southward along the
eastern seaboard. The gusty winds and 30 percent MinRH values could
increase fire activity.

As the aforementioned surface high pressure system slides southward
along the eastern seaboard, it wraps some Gulf/Atlantic moisture
around and shoves it northward into the Tennessee Valley on Sunday
and up towards our area for Monday. At the same time, a cold front
slowly stalls just to our northwest for Monday into Tuesday. The GFS
is 6 hrs earlier than the ECMWF in returning the 60 degree dew
points to the area on Monday afternoon/evening, which would give the
rain chance more moisture to work with and make it more possible to
occur. The front is slow to slide southeast from Monday through
Tuesday night and so there could be continued rain chances somewhere
around the area during this time. The ECMWF has MUCAPE to work with
on Tuesday, but its also within a pretty moist column so perhaps it
all wouldn`t be able to get used by storms or storms would be
elevated/embedded. Shear is around as well later Tuesday, but it may
also not be able to be tapped into if the moist column hinders lift.

It takes until a vigorous clipper system moves from south-central
Canada towards the Northern Great Lakes to finally push the front
through the area and allow high pressure to move back in on
Wednesday. High temperatures are also expected to stair step down
from the low to mid 80s on Monday to the upper 60s on Wednesday of
next week with the passage of this front.

&&

.AVIATION /12Z TAFS THROUGH 12Z FRIDAY/...
Issued at 617 AM EDT Thu Oct 2 2025

Light east flow at the surface prevailed and was accompanied by
VFR conditions. This tranquil pattern will persist over the
area with weak flow through the low and mid atmospheric levels.
Dry conditions through these layers will continue to inhibit
cloud formation under high clouds. Winds should predominately be
light out of the east.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.

&&

$$

DISCUSSION...Roller
AVIATION...Skipper