Indiana’s Weather For Monday

HEADLINES

– Rivers have already reached or are expected to reach moderate to major flood stage in Central and South Central Indiana.
– Widespread, significant river flooding continuing through next the few weeks.
– Frost and freeze conditions likely Monday night and Tuesday night. Freeze Warning in effect tonight.

TODAY’S MAP

NWS TECHNICAL DISCUSSION

Surface Analysis late this morning shows low pressure in place over
Lake Huron, with a trailing dry cold front stretching across MI to
northern IL and N OK. A weak ridge of high pressure was found across
Central Indiana, pointing toward western PA. GOES16 shows a thin
layer of high clouds stretched from NW OH across Central Indiana.
Otherwise much more sunshine was found across Central Indiana this
morning. Light surface winds under the ridge axis were becoming
westerly across Central Indiana.

This afternoon the cold front is expected to advance and pass across
Central Indiana by late this afternoon. Winds will become northerly
in the wake of the front as cold air advection begins. Forecast
soundings show convective temperatures today in the lower 50s which
should be reached by early afternoon allowing CU development.
Forecast soundings by late afternoon suggest the arrival of overcast
skies as the lower levels show saturation amid the cold air
advection. Thus we will expect partly cloudy skies by mid day and
skies becoming cloudy in the wake of the front. Furthermore, gusty
winds will be expected in the wake of the cold front, resulting in
some chilly wind chill values. Overall ongoing forecast appears on
track.

&&

.SHORT TERM (Today and tonight)...
Issued at 258 AM EDT Mon Apr 7 2025

Cloud cover is beginning to quickly dissipate across most of central
Indiana as mid level dry air beneath broad subsidence arrives.
Surface observations are picking up on a weak low level boundary,
with winds calming over the I-70 corridor and points southward. With
subsidence aloft, calming winds and a high surface latent heat flux,
patchy fog is likely to develop over the next few hours over this
region. There is still some uncertainty on the density and spread of
this fog, and will be closely monitored this morning. With fog
developing, and a strong latent heat flux, diurnal temperature drops
are likely to plateau, mitigating some of the frost threat despite
temperatures only a few degrees above freezing. Still, patchy
elevated frost is possible, especially north of I-70.

Today will be slightly warmer as a shortwave and corresponding
modest SW flow arrives late this morning into the afternoon. This
wave will be rather parched, with minimal moisture advection out
ahead. This should keep rain mostly out of the forecast and cloud
cover limited to diurnal alto-cu. There is a bit of strong
confluence as the wave pushed into eastern IN, of which could lead
to a slight uptick in moisture convergence. For this reason a slight
chance of light rain showers have been added for SE central Indiana,
QPF (if any) will remain below 0.1".

Dry SW flow will likely induce a well mixed PBL, resulting in gusty
winds late this morning through the afternoon. Initially, these
winds will be out of the W/SW, but will eventually shift towards the
NW/N after a dry boundary passage. Cold air will usher in behind
this boundary, dropping temperatures back into the 40s. Overnight,
continued CAA will reintroduce below freezing temperatures for all of
central Indiana leading to a Freeze Warning with the growing season
beginning a bit early this year. Isolated to scattered flurries have
been added for the NE 2/3 of central Indiana with the potential for
saturation near the top of the PBL and weak low level instability.

&&

.LONG TERM (Tuesday through Sunday)...
Issued at 258 AM EDT Mon Apr 7 2025

Tuesday and Tuesday night...

Colder weather arrives at the start of the period as northwest flow
continues to filter in cooler air behind a departing trough. A
freeze is expected Tuesday morning as temperatures will be well in
the 20s. At the surface, high pressure builds over the region with
generally quiet weather expected. Forecast soundings show increasing
subsidence aloft, steep low-level lapse rates, and some lingering
low-level moisture which leads to stratocu development during the
day.

Latest CAMs are notably more bullish regarding cloud cover compared
to less coarse global models. Given the NBM or Global models tend to
under forecast cloud cover in these setups, higher resolutions
models were blended in to help increase expected cloud cover. A few
high resolution models even suggest there may be enough low-level
saturation for some light flurries or sprinkles though this appears
unlikely. Look for temperatures to generally remain in the low to
mid 40s due to northwest surface flow and stratocu development.
Surface high pressure moving overhead Tuesday night will likely
promote freezing temperatures once again.

Wednesday onward...

Rain chances begin to quickly increase midweek as a low pressure
system approaches the region. Strengthening isentropic ascent with a
warm front lifting northeastward could allow for precipitation to
begin by Wednesday morning. More widespread precipitation is then
expected late Wednesday into Thursday once deeper moisture and
stronger forcing from the approaching system move in. Thermal
profiles strongly suggest rain will be the dominant precipitation
type, but there is a brief chance for snow to mix in early Wednesday
morning before warm air advection begins. No accumulation is
expected.

Exact QPF amounts remain uncertain due to disagreement
between guidance, but there is consensus in rainfall amounts
remaining under an inch. Other than slightly prolonging river
flooding this system likely won`t have much of an impact on our
waterways. Regardless, widespread river flooding will continue
through the week.

Long range guidance shows a deep upper trough remaining over the
region through late this week along with broad cyclonic flow at the
surface. This will keep a low chance for isolated showers in the
forecast through Friday. Upper ridging then begins to build across
the central CONUS over the weekend supporting quiet weather and
warmer temperatures.

&&

INDY SEVEN DAY FORECAST
Today: Some morning sunshine. Afternoon clouds, and a few light showers or sprinkles. High 55.

Tonight: Evening sprinkle or light shower possible. Clearing and frosty overnight. Low 26.

Tuesday: Mostly sunny. High 45.

Tuesday Night: Partly cloudy. Frosty again. Low 30.

Wednesday: Mostly cloudy. Spotty morning snow showers. Scattered afternoon showers. High 49.

Wednesday Night: Rainy. Low .

Thursday: Scattered showers. High 55.

Thursday Night: Mostly cloudy. Low 36.

Friday: Partly sunny. High 54.

Friday Night: Mostly clear. Low 35.

Saturday: Mostly sunny. High 59.

Saturday Night: Mostly clear. Low 38.

Sunday: Partly sunny. High 66.

NWS CHARTS FOR TODAY/TONIGHT