907
FXUS63 KIND 070129
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
929 PM EDT Mon Oct 6 2025

.KEY MESSAGES...

- Scattered showers through the evening, mainly across southern
  Indiana

- Widespread rain and thunderstorms tonight into early Tuesday,
  heaviest rain across southern Indiana

- Rain amounts will vary between less than 0.25 inches towards
  Lafayette to 1-2 inches towards southern Indiana

- Dry and seasonable weather Wednesday through Friday with low
  chances for rain returning for the weekend

&&

.FORECAST UPDATE...
Issued at 929 PM EDT Mon Oct 6 2025

Showers have gradually increased in coverage across the southeast
half of the forecast area since late afternoon in response to an
increase in the low level jet and progressively deeper moisture
advection into the region between a cold front over Illinois and the
high pressure ridge to the east. An unseasonably humid airmass had
settled over the Ohio Valley with dewpoints in the mid and upper
60s. Temps at 01Z were largely in the upper 60s and lower 70s.

The forecast is in good shape for the overnight with many getting
the opportunity for some much needed rainfall. The low level jet
will strengthen and focus across the southeast half of the forecast
area over the next several hours. The most widespread rainfall
coverage will align in this zone with PWATs rising to 1.75 inches
and greater and model soundings showing deep saturation nearly up to
500mb. Weak instability will be present as well and may produce some
isolated thunder at times through the night as well. Could see
isolated rainfall amounts in excess of 2 inches in spots across
southern counties which may produce localized nuisance flooding
despite the antecedent dry conditions.

Rainfall will be lighter and more scattered further to the north
with drier air lingering above 850mb and gradual moistening of the
column being delayed until closer to daybreak as the cold front
approaches the northern Wabash Valley.

Lows will hold in the mid 60s. Zone and grid updates out.

&&

.SHORT TERM (This evening through Tuesday)...
Issued at 139 PM EDT Mon Oct 6 2025

Rest of Today and Tonight.

Scattered showers associated with a broad area of mid-level
isentropic lift will continue to move northeast across much of
central and southern Indiana through the remainder of the afternoon
hours ahead of the arrival of a strengthening LLJ advecting Gulf
moisture into the southern portions of the state. This moisture
advection will continue to saturate the low and mid-levels with
plentiful lift being forecast after 00Z. There will be some
instability before the mid levels fully saturate and become moist
adiabatic which could bring a few rumbles of thunder, but expect
thunder coverage to be minimal with little to no risk for severe
weather as both instability and shear will be very marginal.

The surface front associated with the parent trough aloft will still
be moving into northern Illinois tonight with most of the forcing
that will be bringing the showers and storms associated more with
the southerly influx of moisture and broader lift. The heavier rain
is expected to begin after 00Z with an initial surge of moisture
from 00Z to 06Z followed by a banding area of precipitation towards
daybreak.

Tuesday.

The frontal passage is expected to occur during the day tomorrow,
but by then the better moisture advection will be southeast of the
forecast area, so other than isolated to scattered light rain
showers, don`t expect much additional precipitation during the day
on Tuesday as the thermal profiles will be moist adiabatic with only
weak frontal lift. There are some signals in cooler air working into
the mid-levels towards the afternoon which could bring some back-end
isolated to scattered showers and storms Tuesday evening as the
atmosphere becomes more unstable.

Total QPF for the event will be highly variable across the forecast
area with areas near Lafayette likely to only see amounts between
0.1 and 0.25 inches as the Gulf moisture remains to the south and
the forcing associated with the front is weak. Confidence in QPF
amounts in those locations is fairly high, while confidence in
amounts across southern Indiana is much lower as there is a lot of
variability as to where the heavier rain bands will set up. A broad
area of 1.25-2.00 inches is expected from roughly Vincennes to
Seymour, but amounts could be locally as high as 3 to 5 inches in
very isolated locations. These much higher amounts are more likely
to be along the Ohio River, but will need to closely monitor
precipitation tonight for any short-fused flood headlines as there
is a potential for a nearly stalled band of heavy rain towards
daybreak tomorrow.

&&

.LONG TERM (Tuesday night through Monday)...
Issued at 139 PM EDT Mon Oct 6 2025

Tuesday Night Through Thursday.

There may be a few lingering light showers Tuesday night but most if
not all the precipitation should come to an end by midnight as the
front pushes southeast into the Appalachians. Cooler weather will
move in behind the front, but the strength of the cold air intrusion
is fairly weak with only a weak connection to the much colder
Canadian air. That being said, the intruding airmass will be much
drier with dew points in the mid to upper 30s which combined with
light winds and clear skies Wednesday and Thursday nights will
create marginally favorable conditions for frost in sheltered
locations across north central Indiana.

Confidence is fairly low with some uncertainty as to how cold
temperatures will drop, but for the most sensitive plants some
protection measures may need to be taken.Daytime highs Wednesday and
Thursday will be on the cooler than normal side as well with most
locations only reaching into the mid to upper 60s.

Friday Through Monday.

Surface and upper level flow will remain fairly stagnant late week
into the early weekend with light and variable surface winds keeping
the pattern persistent into Saturday with continued mostly clear
skies and slightly below normal temperatures. There is increasing
confidence in a clipper-esque system moving in from the northwest
Saturday into Sunday as a potential tropical low travels up the
Eastern Coast. Details are highly uncertain as these systems will be
close enough to interact with each other, but will have to watch out
for the potential for isolated light rain.

This system will also help keep temperatures mild with the warmer
than normal temperatures that were previously forecast looking more
unlikely at this time. Forecast details remain highly uncertain into
next week due to uncertainties in the evolution of the
aforementioned systems, but there is at least some agreement in
temperatures slowly trending warmer with precipitation chances below
normal.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 626 PM EDT Mon Oct 6 2025

Impacts:

- Widespread IFR ceilings developing tonight and continuing into
  Tuesday morning before lifting to MVFR
- Showers becoming widespread through the evening and overnight with
  isolated thunderstorms developing
- Shower coverage becomes isolated to scattered through the day
  Tuesday with gradual drying form the northwest in the afternoon

Discussion:

MVFR stratus has expanded as far north as KHUF and KIND early this
evening with periodic IFR ceilings already impacting KBMG. The lower
stratus will continue to expand north through the evening and will
eventually encompass KLAF as well by late evening or just after.
Rainfall coverage has increased noticeably across the southern half
of central Indiana since late afternoon and expect further expansion
through tonight as deeper moisture and lift expand across the
region. Cannot rule out a few rumbles of thunder at KBMG overnight
with weak instability present. Cigs have already dropped to MVFR
everywhere but LAF with isolated to scattered showers currently
impacting BMG. Coverage is expected to increase through the day with
rain and a few rumbles of thunder expected at BMG through the night
with less frequent coverage at HUF and IND. LAF may see little to no
rain until late tonight. Cigs will continue to drop through the
evening with IFR conditions after 06Z and brief LIFR possible
towards 12Z. Vsbys will predominately remain MVFR to VFR outside of
BMG where IFR vsbys will be common. Winds will generally remains
southerly at 7-12kts through the TAF period.

IFR ceilings will encompass all of the terminals overnight into
Tuesday morning immediately ahead of a cold front poised to cross
the region through the first half of the day. Showers will become
more scattered through midday Tuesday with ceilings recovering to
MVFR levels around 1500ft for the afternoon. There are hints of an
additional line of convection developing along the front during the
afternoon with greatest confidence in impacts at KBMG.

S/SW winds tonight will veer to westerly in response to the
approaching front then shift to N/NW once the front passes on
Tuesday.

&&

.IND WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

UPDATE...Ryan
SHORT TERM...White
LONG TERM...White
AVIATION...Ryan