417
FXUS63 KIND 290422
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
1222 AM EDT Wed Apr 29 2026

.KEY MESSAGES...

- Showers and thunderstorms expected tonight with a threat for heavy
  rainfall and isolated large hail in southern portions of central
  Indiana.

- Flooding threat on area rivers will continue across southern
  Indiana after multiple rounds of heavy rainfall.

- Below normal temps for late this week into the weekend.

- Frost possible this weekend.

- Slow warm up with rain chances returning early next week.

&&

.FORECAST UPDATE...
Issued at 1020 PM EDT Tue Apr 28 2026

Other than a few isolated showers in the far south, this evening has
been dry across central Indiana. However, regional radar shows
showers and thunderstorms across southern Illinois moving east
toward the southern forecast area. Temperatures were in the lower
50s north to lower 60s south under mostly cloudy to cloudy skies.

Forcing will continue to increase and move into central Indiana
tonight with an upper wave as well as surface low pressure to the
south of the area. This will bring rain to much of the area, so kept
high PoPs.

Locally heavy rain remains a threat tonight, especially south closer
to the higher moisture content. Guidance continues to show the
potential for a band of heavier rain setting up somewhere in or near
the southern half of the area. Will continue to mention a threat of
locally heavy rainfall and flooding overnight.

Some elevated instability will move in overnight, mainly south. It
appears that the greatest threat for severe hail will remain south
of central Indiana based on latest trends, but will continue to
monitor closely.

Forecast temperatures look reasonable given expected conditions.

&&

.DISCUSSION (This evening through Tuesday)...
Issued at 314 PM EDT Tue Apr 28 2026

Tonight....

Scattered to numerous TS over Missouri are associated with a broad
WAA pattern ahead of a shortwave trough moving through the central
Plains. This activity will continue to be supported by elevated
instability (MUCAPE from 1000-2000 J/KG) while shifting eastward
into southern half of IL into the evening hours. Recent RAP
mesoanalysis shows the northward extent of the moderate elevated
instability is further north that most of the CAM/12Z HREF guidance
suggested. Therefore, unlike the bulk of guidance which shows less
than 500 J/KG of MUCAPE across the far south parts of the central
IN, expecting with a feed of 8-8.5 C /KM mid level lapse rates
coupled with an increasing low level jet expected to form in the
wake of the Ozarks this evening, MUCAPE values will be roughly
double these values running from 500 J/KG near I-70 to near 1000
J/KG down near the US 50 corridor. Also as a result of the increased
instability, the forecast has gone more bullish with TS chances
across the southern portions of the forecast area as well as
including the mention of locally heavy rainfall. SPC Day 1 outlook
maintains a marginal risk for severe hail in the far southern
portions of the forecast area, but believe that the severe hail
threat is 50-100 mi further north accounting for the greater
instability.

Regarding the heavy rainfall threat, soil moisture values across the
southern portion of the forecast area are running between 50 and 70
percent saturated. Thus it will not take much rain for flash
flooding. OHRFC flash flood guidance has most of this area in 1.5 to
2 inch/6hr and 1.5 inch/3 hr. A Flash Flood watch was considered,
but given some uncertainty in reaching at least 1.25-1.5 inch QPF
overnight, opted to not issue and to let later shifts reassess for
the potential for more cell training and higher amounts.

Wednesday through Friday...

An unsettled and cool pattern will set in for the remainder of the
work week as broad NW flow and several weak mid level perturbations
move across the region around a longwave trough centered over
eastern Canada/CONUS. Just ahead and in the wake of the first
shortwave on Wednesday, CAA and wrap around scattered light showers
are expected in eastern zones during the afternoon. Skies should be
mostly clear Thursday. Low PoPs were added for Thursday Night to
account for the consensus timing of another shortwave which will
move SE across the region pinwheeling around the closed low centered
south of Hudson Bay.

Saturday/Sunday...

As the closed low/long wave trough move gradually east, surface high
pressure will build southward from the northern Plains. The high
pressure ridge axis will be just to the northwest of the forecast
area on Saturday morning, with the potential for some low clouds and
winds remaining 5-10 mph. By Sunday morning, the surface high ridge
axis shifts to nearly over central Indiana per the Euro, but
slightly south of the central Indiana per the GFS. Either way, temps
are expected to be well below normal this weekend with generally
light winds and clear skies. A dry airmass with dewpoints near 32F
will favor the potential for patchy and possibly more widespread
frost, especially in outlying areas both mornings. Highs near 60F
(about 10 deg below normal) are expected for afternoon highs.

Early next week...

Guidance is mixed on the timing of additional shortwave energy
moving out of Canada. In the wake of high pressure, expect at least
a slight warmup to near normal temperatures Monday and Tuesday. NBM
has low PoPs for Monday into Tuesday based on smoothing out the
timing of weak shortwaves in the W-NW flow aloft. Given a frontal
intrusion in the Gulf this weekend, moisture return will be meager
and any precipitation should be primarily showers with isolated sub-
severe TS possible.

&&

.AVIATION (06Z TAF Issuance)...
Issued at 1215 AM EDT Wed Apr 29 2026

Impacts:

- Isolated to scattered TS tonight at all but KLAF.
- MVFR ceilings return overnight at all sites with IFR
  conditions expected at KHUF/KBMG.
- Gusty winds tomorrow out of the NW, peak gusts around 25kt

Discussion:

Ceilings will gradually lower through the VFR category through 06Z
or so, then MVFR and some IFR conditions will develop from the
southwest. IFR is expected by 09Z at KBMG and likely at KHUF. Cannot
rule IFR out at KIND but am not confident enough to include.
Ceilings will gradually improve Wednesday morning, reaching VFR by
around 18Z.

Showers and some thunderstorms will push in from the southwest late
this evening. Showers will then continue at times into Wednesday
morning. Some uncertainty exists on thunderstorm coverage,
especially at KIND.

&&

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

$$

UPDATE...50
AVIATION...Updike/50
DISCUSSION...Crosbie