971
FXUS63 KIND 250141
AFDIND

Area Forecast Discussion
National Weather Service Indianapolis IN
941 PM EDT Thu Apr 24 2025

.KEY MESSAGES...

- Warm temperatures through the work week followed by cooler weather
  this weekend.

- Shower and thunderstorm chances this afternoon through Friday
  night with the best chances Friday and Friday evening.

- Pleasant Spring Weekend ahead.

- More active pattern from Tuesday through Thursday, with
  severe weather potential on Tuesday.

&&

.FORECAST UPDATE...
Issued at 941 PM EDT Thu Apr 24 2025

Only modest adjustments required with this evening`s update. Though
coverage of convection has waned with sunset as expected, some very
isolated activity does continue and cannot be completely ruled out
during the night. Will maintain a 15 pop at least, with chances
increasing toward daybreak as showers arrive ahead of an approaching
broad area of low pressure. Showers should become fairly widespread
Friday with scattered to perhaps numerous thunderstorms as the
system moves into the area later in the day.

&&

.SHORT TERM (This evening through Friday)...
Issued at 259 PM EDT Thu Apr 24 2025

THIS AFTERNOON

Temperatures have warmed to around 80 across the region this
afternoon with dew points steadily rising into the 50s. Some dew
points in the low 60s have been noted across our far south.
Satellite imagery shows cumulus breaking out across portions of our
area especially south of Indianapolis. Cumulus development appears
to be initiating first in areas of differential heating, with the
forested areas of Monroe and Brown Counties being a particular focal
point.

ACARS soundings out of IND show a deeply mixed but largely dry
boundary layer as of 18z. Additionally, lapse rates are rather poor
within the free atmosphere. The lower levels should moisten with
time as southerly winds bring higher dew points northward.

Short-term guidance shows continued heating and moistening leading
to modest destabilization as the afternoon progresses. CAPE values
between 1000 and 1500 J/Kg are possible, especially from
Indianapolis southward where the richer moisture resides. Showers
and some thunderstorms are expected by the evening. Areas where the
cumulus field currently appears agitated (Monroe and Brown Counties)
may be the first to see convective initiation within the next few
hours.

As for severe potential, today`s threat appears very low mainly due
to limited shear through the effective cloud layer. Guidance is
showing values around 20kt bulk shear which may be enough to lead to
some multicell clusters. Storms should be short-lived as they rain
into themselves in the low-shear environment. Small hail and an
isolated downburst with strong sub-severe wind gusts is possible in
the strongest storms.

OVERNIGHT

Storm activity should die down overnight as diurnal heating is lost.
A few isolated showers may persist as moisture advection continues
through the night. Low-level clouds likewise continue through the
night and may even thicken some as moisture increases. This should
keep lows from dropping much, with values in the high 50s to low 60s
expected.

FRIDAY

The threat for showers and thunderstorms returns on Friday as an
upstream mid-level wave approaches from the west and passes just to
our north. The large-scale setup is rather messy with multiple
vorticity features shown in various models, likely originating from
upstream convective activity. As such, convective coverage and
timing on Friday is a bit uncertain. However, it does appear the the
first half of the day is more likely as most guidance has a surface
cold front sweeping through by 00z.

Severe potential on Friday also seems low but not quite as low as
today. CAPE Profiles are a bit taller and thicker with an overall
more moist column. However, shear remains on the low side (30kt at
most) and lapse rates remain poor (6-6.5 C/Km). Our primary threats
would be isolated strong wind gusts and marginally severe hail
within the strongest updrafts. Given the moist column, heavy rain is
possible at times which could lead to localized flash flooding if
storm training occurs.

Things quiet down once the cold front passes through. Low stratus
may persist in the post-front environment as trajectories originate
off of Lake Michigan which should keep the boundary layer moist.

&&

.LONG TERM (Friday night through Thursday)...
Issued at 259 PM EDT Thu Apr 24 2025

Friday Night through Monday -

Overall, a pleasant spring weekend appears in store for Indiana.

Rain chances will linger for a few hours on Friday evening as the
last bits of the surface low pressure and associated cold front
exits Indiana during the evening hours. Overnight, high pressure
from the northern plains will continue to settle across the Ohio
Valley. Forecast soundings late Friday night and into Saturday show
a dry column and HRRR suggests precipitation exiting the forecast
area by 05Z. Thus will keep low chance pops in play during the
evening hours, but trend toward a dry forecast overnight.

Strong ridging aloft over the region will be the rule through the
weekend and into Monday. This ridge is expected to provide continued
subsidence along with an associated large surface high pressure
system that will slowly pass across the state through Monday.
Forecast soundings show mid level inversions along with very high
convective temperatures, thus CU will not be expected, and we will
look for mostly clear skies with only some passing CI through
Monday. As the high slowly drifts east by Monday, southerly flow is
expected to return. This will lead to the typical slowly warming
temperatures each day as the high passes to the east.

Tuesday through Thursday -

Active weather is set to arrive for the middle of next week. Models
show the arrival of SW flow aloft as the previously mentioned upper
ridge drifts east of Indiana. This will set up moist, tropical flow
aloft streaming across the southern plains and into the Ohio Valley.
This quick, moist flow aloft will be favorable for shower and storm
development, particularly on Tuesday. Models on Tuesday show a wave
of energy within the flow aloft streaming toward Indiana. Meanwhile
within the lower levels, a quick, warm and moist flow will also be
in place over Indiana as a low pressure over the Great Lakes and an
associated trailing cold front approaches from IA. This will be a
favorable set-up for storms. Early forecast soundings for Tuesday
afternoon suggest CAPE over 1800 J/KG. Thus high confidence for rain
on Tuesday afternoon and we will continue to monitor for severe
weather potential.

Rain chances are expected to continue as we go through the middle
part of the work week. Aloft a broad upper trough is expected to
remain in place over the plains with continued southwest flow aloft.
More forcing dynamics are show to be passing across Central Indiana
during Wednesday and Thursday. Furthermore, a favorable set-up for
rain and storms will remain in place with the lower levels as models
show the tail of the previously mentioned cold front stalled and
elongated over Central Indiana in a east to west fashion. Given
these ingredients, confidence is high for rain during the middle of
next week and expect high chance to likely pops to be used.

&&

.AVIATION (00Z TAF Issuance)...
Issued at 726 PM EDT Thu Apr 24 2025

Impacts:

- Localized MVFR ceilings possible near daybreak Friday in showers

- Thunderstorms possible again Friday, but too low probability for
  explicit mention at this time

Discussion:

As broad low pressure moves into and through the area tonight into
Friday, increasingly widespread cloud cover is expected, along with
showers and perhaps scattered thunderstorms, particularly Friday
morning into the afternoon hours. Impact of thunder at any one
location this far out is far too uncertain for explicit mention in
the TAF.

Increasing low level moisture will allow ceilings to drop near or
just after daybreak Friday as the showers move in, but at this point
think MVFR ceilings will be transient at most sites but perhaps BMG,
where guidance is a bit more aggressive.

Precipitation threat will come to an end very late in the period as
the cold front passes through the area, though trapped low level
moisture may produce more widespread lower ceilings in the wake of
the front, along with a few gusty winds at or beyond the end of the
period.

Winds will be generally southerly around 10KT or less overnight,
becoming more southwesterly with time and then northwesterly in the
wake of the front tomorrow evening.


&&

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

$$

UPDATE...Nield
SHORT TERM...Eckhoff
LONG TERM...Puma
AVIATION...Nield