Indiana’s Weather For Monday

HEADLINES
– Nice today! Last day above average through Memorial Day.
– Showers and storms tomorrow, with a small severe risk.
– Most likely time: Tuesday afternoon and evening.
– Showers linger through Wednesday and Thursday.
– Rain could exceed one inch through that stretch.

RAINFALL

TODAY’S MAP

NWS TECHNICAL DISCUSSION

Surface analysis early this morning shows a large area of high
pressure over Ontario, with a ridge axis extending south across the
Great Lakes and Indiana to the Ohio River and Kentucky. Light
northeast surface flow was in place across Central Indiana with this
feature. Ongoing convection was found stretching from NB to SE MO
and to western TN. High CI, blow off from the convection was flowing
downstream, across Illinois and Indiana. Surface low pressure was
found over NW KS, and the previously mentioned convection was close
to an associated warm frontal boundary. Dew point temperatures
across Central Indiana were mainly in the 40s. Water Vapor shows a
ridge in place through the Mississippi Valley, providing northwest
flow aloft over Indiana and lee side subsidence. The windward side
of the ridge was will with lift and storms as a short wave within
that flow was moving northeast.

Today -

Models show the ridge axis and associated short wave pushing into
Indiana today, with much of the day marked within the lee side
subsidence area. The short wave aloft and associated forcing is
expected to push toward Indiana along with what should be the
remnants of the ongoing convection. Meanwhile within the lower
levels, the ridge of high pressure extending from the north will
slowly move east through the day, exiting Indiana. However it will
remain the dominate weather player within the lower levels. HRRR
shows remnants of the convection arriving in Central Indiana this
afternoon, mainly in the western 1/2 of the forecast area. Forecast
soundings remain dry across the forecast area through the day with
dry lower levels due to easterly wind. An exception here are points
across the SW parts of the forecast area, including Vincennes,
Sullivan, Washington and Linton. At those locations, forecast
soundings show some instability during the late afternoon as the
warm front to the southwest approaches. This may result in slightly
better chances for a late afternoon shower or storm.

The high clouds today should result in skies only being partly sunny
today. Isolated showers cannot be ruled out, but precipitation
should be rather light, thus pops will be kept small. The easterly
winds expected tonight will continue to provide near normal high
temperatures in the lower to mid 70s.

Tonight -

As a deep upper low moves into the northern plains, southwest flow
aloft with this system is poised to eject forcing dynamics across
the Mississippi Valley during the evening and toward and across
Indiana overnight. Furthermore, the associated trough axis with
this feature to the west is negatively tilted. HRRR suggest evening
convection/MCS development over the middle Mississippi valley, with
propagation to Central Indiana overnight. The arrival of the storms
during the overnight hours will be a diurnally unfavorable time for
severe weather, but thunderstorms with brief heavy rain appear
likely. Forecast soundings show a saturated column after 06Z Tues as
these features arrive. Thus will aim for a continuation of today/s
weather, mainly dry, into the evening hours, but ramp pops upward
overnight with the expected MCS remnants pushing across Indiana.

Given the expected clouds and rain, overnight low temperatures will
be warmer, in the middle and upper 50s.

&&

.LONG TERM (Tuesday through Sunday)...
Issued at 323 AM EDT Mon May 19 2025

Active weather returns this week and below normal temperatures
through early next week. An upper trough with a negative tilt will
bring a chance of severe weather to start the long term. Guidance is
showing that central Indiana will likely be just north of the warm
sector so it may take until later in the day for the area to get the
needed instability and overcome the likely morning cap. Large-scale
forcing increases markedly as frontal upglide, vorticity advection,
and favorable jet streak dynamics all line up. As such, most
guidance depicts copious amounts of precipitation across a large
section of the area and the potential for training storms could pose
a risk for flooding. With this system, all severe hazards are on the
table, particularly for south of the warm front.

South of the warm front, some guidance suggests that morning precip
clears out enough to allow for further destabilization. RAP
soundings show a wider and deeper CAPE profiles with long looping
hodographs. A greater severe weather threat would be possible should
the warm sector clear out enough for this to materialize. Right now,
it looks like the front will be across the southern portions of our
CWA thus confining the threat. However, a lot depends on prior
convective evolution which would alter the boundary`s position
somewhat.

As for Wednesday onward, the parent trough moves in and occludes
over the region. We`ll see a few days with mostly cloudy skies, rain
showers, and below-normal temperatures. The start of this weekend
will see the best chance for drier weather although still on the
cooler side thanks to northwesterly upper flow dominating. Rain
chances again increase for Sunday and Monday with the potential for
another low to form. While models are pretty noisy at this time,
providing lower confidence, leaning towards the chances that much of
central Indiana staying dry on Sunday as rain could stay to the SW
of the area before more likely moving in Monday or beyond. Will
continue to monitor for the holiday weekend.

INDY SEVEN DAY FORECAST
Today: Partly sunny. High 76.

Tonight: Clouds thicken. Shower chance after midnight. Low 54.

Tuesday: Periods of showers and storms. A few could be severe. High 71.

Tuesday Night: Showers and storms. A few could be severe. Low 58.

Wednesday: Scattered showers. High 66.

Wednesday Night: More scattered showers. Low 50.

Thursday: Partly to mostly cloudy. Scattered showers. High 63.

Thursday Night: Partly cloudy. Low 44.

Friday: Partly sunny. High 63.

Friday Night: Partly cloudy. Low 45.

Saturday: Partly sunny. High 66.

Saturday Night: Partly cloudy. Low 51.

Sunday: Partly sunny. High 71.

NWS CHARTS FOR TODAY/TONIGHT