Indiana’s Weather For Today

Monday morning headlines..
– Widespread rain expected today with a few thunderstorms possible

– Wind gusts between 25-35 mph possible today

– Rainfall chances beginning early Wednesday morning and continuing
through Wednesday afternoon

– Cooling trend Wednesday onward

Technical discussion via the National Weather Service

Warmer air moving north has ended the dense fog across central
Indiana, but patchy fog and drizzle remain. Scattered showers were
developing across Illinois with some isentropic lift ahead of an
approaching upper trough. Convection was across southern Illinois
and western Kentucky, associated with an 850mb jet.

The isentropic lift will move into the forecast area by 12Z, and the
850mb jet will approach from the southwest. The result will be
increasing coverage of showers. Will go with likely or higher PoPs
across the western half or two-thirds of the area by 12Z. A rumble
of thunder is possible south where some elevated instability will be.

Today...

The isentropic lift will move east across the area this morning.
Meanwhile a strengthening low level jet will move in, with the focus
on the far southern forecast area. This will bring plentiful
moisture. Aloft, the upper trough will approach from the west. Will
go high PoPs most areas at some point during the morning into early
afternoon. Some mainly elevated instability will be around,
especially south, so a rumble of thunder will continue to remain
possible.

This afternoon, the broader rain shield will be moving east out of
the area. Meanwhile, a cold front will move in from the west. There
will be some weak instability for the front to work with, and there
will be a good amount of shear.

At the moment, believe that instability will remain quite weak, so
that only some showers will develop with the actual cold front. If
instability becomes higher than anticipated, convection might become
organized enough to produce some strong wind gusts. However,
confidence in that scenario remains low.

With the focus of the low level jet to the south of the area,
rainfall amounts will range from less than a quarter of an inch in
the northwest to near three quarters of an inch southeast.
Convection to the south may rob some of this moisture, which would
result in lower rainfall amounts, especially north.

Wind fields will remain high enough that some gusts in the 25 to 30
mph range are likely this afternoon, with perhaps some gusts up to
35 mph.

Warm advection ahead of the cold front will bring high temperatures
in the middle 50s to lower 60s, which is well above normal for mid-
December.

Tonight...

Colder and drier air will work into the area behind the cold front.
Some lower clouds will linger in the northern forecast area, while
the southern area should become mostly clear. Temperatures will
fall into the lower to middle 30s for lows.

&&

.LONG TERM (Tuesday through Sunday)...
Issued at 234 AM EST Mon Dec 16 2024

A return to cooler conditions is anticipated during the long range.
Aloft, the jet pattern will shift from quasizonal to more amplified
with troughing dominant over the eastern seaboard. Such a pattern
typically brings dry and cooler conditions since northwesterly flow
prevails. These conditions can largely be expected by the end of the
long range. However, before we fully switch into such a pattern
there is at least one more wave embedded within the zonal flow
aloft. This wave is expected to arrive early on Wednesday bringing
another round of precipitation.

Model uncertainty remains on the higher side regarding this system,
mainly in terms of its track. Outcomes for the main precipitation
axis currently ranges from the I-70 corridor on the northern edge,
to near and south of the Ohio River on the southern edge.
Regardless, this wave will likely still be early in its life cycle
as it arrives Tuesday night into Wednesday, without a true cold
conveyor belt formed. The result is a much warmer thermal profile,
of which will likely keep any frozen precipitation north of central
Indiana, ahead of the mid level trough. If there is any snow, it
would be light, and on the backside of the southern most scenario
late on Wednesday (currently would put chance of occurrence around 10-
25%). As far as precipitation timing, trends are pushing
precipitation onset post 09Z in far western IN, with precipitation
ending sometime Wednesday afternoon/evening. The further north the
system tracks, the later precipitation will end on Wednesday.

Once the mid-week system departs, troughing begins to dig over the
eastern seaboard and our transition to northwesterly flow commences.
As such, temperatures trend downward towards colder more winter-like
values. Though the overall pattern will be dry, guidance shows a
clipper system (some members depicting a fairly robust low) diving
southeastward towards the end of the week with potential impacts to
Indiana. Most guidance keeps Indiana largely dry as the bulk of the
precipitation associated with the system is on its northern flank.
There are a few members that bring snow showers to the region,
however. Temperatures on Friday will depend on how strong the system
is, and where it tracks. Regardless, cold conditions are likely to
follow with renewed cold air advection behind the departing system.

INDY SEVEN DAY FORECAST
Today: Rainy and breezy, with gusts to 30 mph. Some thunder possible. High 59.

Tonight: Wind decreases, with some clearing later. Low 33.

Tuesday: Mostly sunny. High 47.

Tuesday Night: Clouds increase. Low 35.

Wednesday: Morning snow and rain showers. Cloudy. High 43.

Wednesday Night; Mostly cloudy. Low 25.

Thursday: Mostly cloudy. High 37.

Thursday Night: Cloudy. Snow showers possible after midnight. Low 28.

Friday: Morning snow showers. Light accumulations possible. High 35.

Friday Night: Partly cloudy. Low 22.

Saturday: Partly sunny. High 32.

Saturday Night: Partly cloudy. Low 16.

Sunday: Mostly sunny. High 31.

NWS CHARTS FOR TODAY/TONIGHT