207
FXUS63 KIND 261342
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
942 AM EDT Sun Apr 26 2026

.KEY MESSAGES...

- Severe thunderstorms possible Monday afternoon into Monday night.

- Showers and thunderstorms possible on Tuesday, especially over
  southern Indiana.

- Cooler temperatures expected Wednesday through Saturday.

&&

.FORECAST UPDATE...
Issued at 941 AM EDT Sun Apr 26 2026

Surface analysis this morning shows high pressure in place over
Ontario and Quebec, spilling southwest across the Great Lakes to
Indiana. This was resulting in a cool, dirty, easterly flow. GOES19
shows stratus clouds within the flow lingering across OH and much of
Indiana. Aloft water vapor shows ridging in place over Indiana and
the Great Lakes extending into eastern Ontario. Strong subsidence
was shown over Indiana. Temperatures across the the forecast area
were mainly in the lower 50s.

This afternoon, diurnal heating will allow for the mixing out of the
stratus clouds, and more sunshine will be expected. Forecast
sounding this afternoon show a very dry column underneath the
subsidence, and CU development is not expected. Given the expected
afternoon sunshine, highs should once again reach the lower to
middle 70s. Overall, the ongoing forecast appears on track.

&&

.DISCUSSION (Today through Saturday)...
Issued at 307 AM EDT Sun Apr 26 2026

High pressure strengthening over the Great Lakes is driving a
northeasterly wind across Indiana. Moisture off the lakes beneath a
subsidence inversion has allowed widespread stratus to develop. The
stratus is gradually spreading westward, having reached Indianapolis
around 1am. Stratus may progress as far as the Illinois border by
sunrise. After that, boundary layer mixing should promote the slow
dissipation of the low clouds by this afternoon. High temperatures
today will depend on how quickly this process occurs. Locations that
escape the stratus deck should warm nicely into the mid to upper
70s, mainly over our southwestern counties. Further northeast, highs
in the low to mid 70s are more likely.

MONDAY`S SEVERE WEATHER POTENTIAL

Guidance is in good agreement showing a potent shortwave trough
ejecting out of the Rockies late Sunday. This feature moves
northeastward fairly quickly, passing to our north Monday evening.
Surface cyclogenesis progresses rapidly on Monday over the Great
Plains, with the resulting low strengthening to between 990-998mb.
Such deepening will help drive a potent mass response, lifting a
broad warm/moist sector rapidly northward. Additionally, a
developing low-level jet (LLJ) is modeled to strengthen through the
day Monday and especially into Monday evening.

Flow at the surface may still be out of the east-southeast Monday
morning, as today`s surface high slides eastward. This may limit
moisture return over Indiana, with some CAMs showing relatively dry
conditions Monday afternoon (RH as low as 30 percent). Winds
gradually become more southerly through the day, allowing dew points
to increase into the evening hours. Guidance with a dry boundary
layer tend to have as much as 1500 J/Kg less MLCAPE.

Further to the west, especially over Illinois, rich moisture is
shown by most guidance. Dew points well into the 60s with
corresponding CAPE values between 2000-3000 J/Kg. Model soundings
show steep lapse rates, between 7-8 C/Km. Hodographs are long and
curved. Further east, however, upper-level flow decreases quickly
and hodographs are curved but not nearly as long.

Two scenarios exist for convective evolution on Monday. First,
convection that fires up this afternoon over Kansas grows upscale
into an MCS and propagates eastward through the night into the
strengthening LLJ. Some CAM guidance, like the 00z HRRR, show such a
scenario. Of particular interest is the relatively dry air mass over
Indiana and whether this causes an approaching MCS to quickly
weaken. It is also possible that moisture advection keeps pace with
the MCS allowing it to propagate into Indiana Monday afternoon.

The second scenario is that there is no MCS, or it goes well to our
north, and thunderstorm development occurs over Illinois along the
low`s trailing cold front. Such a scenario would allow instability
to build up until explosive convective development occurs. Shear
vectors slightly off parallel should allow for initially discrete
convection, with shear magnitudes favoring supercells over Illinois.
Upscale growth into a line or MCS appears likely with eastward
extent. Moisture advection ahead of the front should allow
convection to sustain through Indiana and into Ohio.

All hazards are possible with Monday`s severe weather, especially
with any supercells that develop. Strong to damaging winds are
favored with upscale growth or in scenarios that result in an MCS.
Given the strong LLJ and high amounts of SRH (200-300 m2s2) present
within the warm sector, a QLCS tornado threat is possible as well.

TUESDAY ONWARD

A second shortwave ejecting from the Rockies closely behind Monday`s
may provide another chance at showers and storms. However, given the
potency of Monday`s system, much of the moist unstable air will have
been swept away by the time the second system arrives. Sufficient
moisture return may be possible for storms over the southern half of
Indiana late Tuesday. Severe weather may again be possible should
this occur, especially further south, but this depends on how
quickly moisture and instability can advect back northward.

After Tuesday, persistent troughing aloft takes hold and cooler
conditions are favored for the second half of the week. High
temperatures in the 60s and lows in the 40s appear likely Wednesday
through Saturday.

&&

.AVIATION (12Z TAF Issuance)...
Issued at 634 AM EDT Sun Apr 26 2026

Impacts:

- MVFR ceilings this morning, improving after 15z.
- Wind gusts 20 to 25 kt Monday.

Discussion:

MVFR stratus has arrived from the northeast with ceilings around
1400 ft agl at KIND as of 11z. Stratus should persist through
sunrise with gradual improvement after 15z. High cirrus arrives
during the afternoon around the same time the stratus begins to
dissipate.

Winds are taking on an east-northeast direction between 5-10kt with
little change in either speed or direction expected through 15z
Monday. After that, winds become southeasterly while increasing to
between 10-15 gusting to 25kt.


&&

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

$$

UPDATE...Puma
AVIATION...Eckhoff
DISCUSSION...Eckhoff