316
FXUS63 KIND 181855
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
255 PM EDT Sat Apr 18 2026

.KEY MESSAGES...

- Showers and isolated thunderstorms this afternoon, mainly south
  and east of I-69, diminishing this evening.

- Low temperatures in the 30s tonight, and near freezing Sunday
  night. Widespread frost likely.

- FROST ADVISORY tonight from 2am to 9am.

- FREEZE WATCH Sunday night / Monday morning from 2am to 9am.

- Warming trend beginning on Tuesday.

&&

.DISCUSSION (This evening through Saturday)...
Issued at 254 PM EDT Sat Apr 18 2026

A cold front is passing through central Indiana, with
northwesterly winds now being reported along with a 5 to 10 degree
temperature drop. This front will continue east ward exiting into
Ohio by late morning. Temperatures then continue to fall into the
afternoon with high temperatures being set largely before noon.
Readings into the upper 40s / low 50s are expected for much of the
afternoon hours.

Stratiform rain is ongoing as of 9am, with no embedded convective
elements noted on radar. We`ve lowered lightning/thunder
probabilities to below mentionable (under 15 percent), except in our
far southeast. Rain showers may continue on and off into the early
afternoon hours, though the steady rainfall will have come to an end
by then. Some CAMs show elevated convective elements developing
later in the afternoon over southern Indiana, which is why the
mention of thunder was retained across our southeast.

Cloud cover rapidly clears behind the front as large-scale
subsidence settles in. At the surface, high pressure arrives
allowing winds to diminish to under 5kt. Cold air advection remains,
however, as 850mb temperatures are modeled to fall into the 0 to -5
degree C range. With good radiational cooling potential, lows in the
30s are likely tonight especially outside of urbanized areas. Frost
is also becoming increasingly likely, and a Frost Advisory has been
issued for tonight into Sunday morning.

Large-scale troughing digs in this weekend and is expected to
persist into the new week. A subtle vort max embedded within the
trough may bring a few showers Sunday afternoon. With no substantial
air mass change following the vort max, near to below normal
temperatures are likely to continue through at least Monday. Good
radiational cooling and thus frost potential is again possible
Sunday night into Monday morning with lows near to below freezing. A
Freeze Watch has been issued Sunday night into Monday morning.
Strong April sunshine should at least allow high temperatures both
Sunday and Monday to rebound into the high 50s to near 60.

High pressure slides east of Indiana late Monday night, with
strengthening southwesterly flow behind it. As such, a warming trend
is anticipated as warmer air once again flows northward. Ensemble
guidance is in good agreement showing high temperatures climbing
back to near 70 on Tuesday. Temperatures may end up being a bit
higher than guidance, since mixing tends to be more efficient within
southwesterly flow situations. Therefore we will go above guidance
for highs on Tuesday with values in the mid to upper 70s. A weak
front may arrive late in the day Tuesday with some showers, but
confidence in this scenario playing out is fairly low at the moment.
We will introduce low-end PoPs to account for the possibility,
however.

Ridging builds over the Plains through next week allowing the
warming trend to continue. Highs in the 70s to low 80s are once
again possible Wednesday through Friday. The upcoming pattern is a
bit more progressive, compared to this past week, and another strong
cold front appears likely by late Friday or early Saturday. Cooler
temperatures are favored next weekend.

&&

.AVIATION (18Z TAF Issuance)...
Issued at 130 PM EDT Sat Apr 18 2026

Impacts:

- Wind gusts 20-30kt this afternoon, diminishing this evening.
- Scattered showers early, brief reductions in visibility possible.
- Wind gusts between 20-30kt once again on Sunday.

Discussion:

A cold front has moved through central Indiana with winds now out of
northwest at all terminals. Winds are between 15-20kt sustained with
gust to around 25-30kt. These winds die down overnight as surface
high pressure arrives.

IFR to MVFR ceilings persist across the area and are gradually
clearing as high pressure builds in and dry air flows in from the
northwest. Rain showers are present but should gradually decrease as
the front moves further away. Some brief reductions in visibility to
MVFR are possible.

Winds turn westerly and increase again on Sunday as an weak mid-
level system passes just to our north. Wind gusts are expected to
again be between 20-30kt. Additionally, a few rain showers are
possible Sunday afternoon just beyond the end of the current TAF
period.


&&

.IND WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from 2 AM to 9 AM EDT Sunday for INZ021-028>031-
035>049-051>057-060>065-067>072.

Freeze Watch from late Sunday night through Monday morning for
INZ021-028>031-035>049-054>057.

&&

$$

AVIATION...Eckhoff
DISCUSSION...Eckhoff