375
FXUS63 KIND 281927
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
327 PM EDT Mon Sep 28 2026

.KEY MESSAGES...

- Patchy fog possible Tuesday morning.

- Mostly sunny through mid week with well above normal temperatures
  in the 80s.

- Dry conditions persist through Thursday with rain arriving
  Thursday night and then continuing into the weekend.

- Much drier and seasonably cool weather expected next week.

&&

.DISCUSSION (This evening through Monday)...
Issued at 326 PM EDT Mon Sep 28 2026

Mostly tranquil, albeit warm, weather will continue to be the rule
across central Indiana through Wednesday. A signal exists for areas
of patchy fog to develop across mainly northern portions of central
Indiana towards daybreak Tuesday. With the ground gradually getting
colder and drier, and low temps tonight not expected to be as low as
last few nights, don`t see the same ground fog development potential
like we had the last few nights. Have therefore removed the mention
of patchy fog in southern areas. Recycled continental air around the
surface high pressure moving into the Ohio Valley by Tuesday morning
and the southern Apps by Wednesday morning will provide for low
dewpts through Wednesday. Thanks to relatively long nights, this
will lead to fairly large diurnal temp durations, characteristic of
much of the western CONUS, but also fairly usual for Indiana in the
early Fall. Above normal highs will be mostly in the 80s Tuesday and
Wednesday with upper 80s expected south of I-70 for Wednesday and
Thursday as 850 temps rise to +17 and low level mixing gradually
increases owing to an increasing pressure gradient.

The tendency for rain chances continues to slow down across the
region thanks to 2 main factors, 1) the reintensification of the
upper ridge over the SE CONUS north of a developing Tut low over the
Gulf and 2) the strength of the cyclogenesis over the plains
associated with the phasing of the shortwave trough energy over the
SW CONUS with the remnants of the E. Pacific Hurricane Polo. As a
result, despite recent NBM guidance suggesting low pops Thurs
afternoon in northern regions, there appears to be negligible chances
of precip until Thursday night across central Indiana. Not until
Friday does the primary frontal boundary move into central Indiana.
QPF output varies, but overall 0.5 to 1.5 inches, in line with the
WPC forecast which seems reasonable. Sufficiently high PWAT, around
1.5 inches, will support threat for locally heavy rain, but recent
dry spell and lower river levels should limit hydro concerns.

The forecast gets a little more complicated by the weekend. The
track of a subtle tropical shortwave out of the Gulf around the
upper ridge into the SE CONUS will dictate whether another round of
precip will move into central Indiana by late Saturday. Model
consensus remains that this precip chances should end by Saturday
afternoon as the primary forcing mechanisms diminish from the west.
However, the AIGFS remains the main outlier showing a secondary
surge of tropical moisture with PWATs around 1.7 inches and 30-40 kt
low level jet associated with the tropical system aiding in strong
mass convergence. 24hr QPF amounts from 2.5-3.5 inches are still
being advertised by Sunday morning by this model.

Whether this system take shape or not, the larger scale pattern will
become more dominated by a long wave trough developing over eastern
Canada and the Northern CONUS. An associated broad area of surface
high pressure will build southward through the Plains and into the
MS valley by early next week behind an associated cold front. Much
drier and seasonably cool weather will follow well into next week.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 119 PM EDT Mon Sep 28 2026

Impacts:

- Patchy fog generating IFR conditions expected at KLAF early
  Tuesday morning, with MVFR conditions expected at KBMG early
  Tuesday morning

Discussion:

VFR conditions are expected for all the terminals this afternoon
and evening as light N-NW winds prevail. As surface high pressure
centered over the upper MS valley shifts SE, expect winds to
become light NE and then light and variable overnight.

A signal exists for areas of patchy fog to develop across mainly
northern portions of central Indiana towards daybreak Tuesday. With
the ground gradually getting colder and drier, and low temps
tonight not expected to be as low as last few nights, don`t see
the same ground fog development potential like we had the last few
nights. As a result have backed off on IFR conditions at KBMG,
with MVFR now expected. Have maintained tempo IFR vis conditions
for the expected patchy fog at KLAF.

Winds will become light SE as high pressure shifts to the east of
central Indiana by Tuesday morning. Any patchy fog at KLAF will
be done no later than 12Z. Winds are expected to become southerly
at KIND by early afternoon with speeds remaining under 10 kts.


&&

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

$$

AVIATION...Crosbie
DISCUSSION...Crosbie