IND issues Area Forecast Discussion (AFD) at Jul 28, 10:03 PM EDT365
FXUS63 KIND 290203
AFDIND
Area Forecast Discussion
National Weather Service Indianapolis IN
1003 PM EDT Mon Jul 28 2025
.KEY MESSAGES...
- Heat Advisory in effect through 8PM Tuesday.
- Scattered storms possible through this evening.
- Greater storm chances Wednesday and Thursday with the potential
for localized flooding. Isolated strong to severe wind gusts cannot
be ruled out.
- Cooler temperatures and dry weather in store for end of week into
the weekend.
&&
.FORECAST UPDATE...
Issued at 1002 PM EDT Mon Jul 28 2025
No significant changes needed to the forecast this evening. Trimmed
PoPs back as precip is leaving the CWA as of 10pm. Expect lingering
anvil cirrus for a good portion of the night that should gradually
thin with time. Patchy fog is possible by morning as winds are light
and boundary layer moisture is high. Fog will be more likely in
areas that see complete clearing.
&&
.MESOSCALE UPDATE...
Issued at 517 PM EDT Mon Jul 28 2025
Surface observations show an area of low-level convergence across
the southern portion of our CWA. Convection is beginning to fire up
along this zone which stretches from Sullivan through Bloomington
towards Brownstown.
ACARS soundings out of IND, though north of the boundary, show ample
MLCAPE upwards of 2000 J/Kg with a pronounced mid-level dry layer
around 500mb. South of the boundary, the Louisville/SDF ACARS shows
slightly higher MLCAPE near 3000 J/Kg. The dry layer still exists
but is less pronounced. Both soundings contain DCAPE near 1000 J/Kg.
SPC Mesoanalysis is showing near 4500 J/Kg MLCAPE along the western
portions of the boundary over Knox county, which is un-sampled by
any relevant soundings. Indeed, the tallest updrafts have been over
the western portion so far as of 5pm.
Effective shear is essentially non-existent, so storms will exhibit
pulse-like single cell behavior this afternoon. Cores may develop
rapidly before collapsing and weakening. Some growth into weak
multicell clusters may also occur as cold pools develop. Our primary
hazard will be brief wind gusts to between 40-50mph. An isolated
severe wind gust (60mph) cannot be ruled out but this seems
quite unlikely.
Flooding is also possible should storms remain in one location long
enough. Given the expected tendency for updrafts to be short-lived
and outflow dominant, this too remains a low probability.
&&
.SHORT TERM (This evening through Tuesday)...
Issued at 304 PM EDT Mon Jul 28 2025
Current KIND radar imagery depicts quiet weather conditions across
central Indiana. However, latest visible satellite imagery shows an
expanding cu field over the area due to daytime heating of an
anomalously moist PBL. Further destabilization through the afternoon
should aid in the development of isolated or scattered convection.
The greatest chances for storms through the evening will be across
the south where stronger destabilization is expected.
Deep moisture in place combined with a deep warm layer will support
efficient rainfall rates which could lead to localized flooding if
any training occurs. An isolated strong to severe wind gust cannot
be ruled out either with moderate-strong instability and steepening
low-level lapse rates. Forecast soundings show strong DCAPE values
supporting this threat. Weak deep-layer shear will limit any
organized severe threat.
Look for convection to diminish in coverage overnight, but weak
forcing from a subtle wave and any remnant boundaries may once again
allow for a few showers or storms to linger. Decided to keep the
forecast dry due to weak overall forcing and little to signal from
guidance, but low POPs may need to be added in future updates.
Mostly quiet weather conditions are expected on Tuesday with hot and
humid conditions persisting. Look for peak heat indices to approach
or exceed 105F across much of central IN during the afternoon.
Forecast soundings depict stronger subsidence and dry air aloft
compared to today. A capping inversion is also evident which should
help to prevent diurnal showers or storms.
Guidance trends will need to be monitored though as an upstream MCS
propagates towards Indiana. The cluster of storms will likely
dissipate before reaching the area, but any remnant outflow boundary
may help to initiate isolated storms across the northwest.
&&
.LONG TERM (Tuesday night through Monday)...
Issued at 304 PM EDT Mon Jul 28 2025
Tuesday night through Thursday...
An upper wave and frontal boundary is expected to move through the
region early in the period leading to increasing rain chances. Rain
chances begin to increase Wednesday morning with chance to likely
POPs lingering through Thursday as the aforementioned boundary
briefly stalls.
Strong destabilization ahead of the boundary is expected with some
strengthening of mid-level flow. This may support the potential for
loosely-organized thunderstorms capable of producing isolated
damaging wind gusts on Wednesday. Forecast soundings depict steep
low-level lapse rates and drier air aloft promoting strong DCAPE
values. Warm rain processes aiding in efficient rainfall rates could
also lead to localized flooding, especially if training convection
occurs. The localized flooding threat should persist into Thursday
and an isolated strong to severe storm cannot be completely ruled
out across the south if sufficient destabilization occurs.
Hot and humid conditions are expected again Wednesday, but the Heat
Advisory was not extended due to greater convective chances leading
to more uncertainty in peak heat index values. Latest CAMs also show
potential for a weakening MCS to propagate towards the area. Any
precipitation or convective cloud debris from upstream convection
and the approaching wave could potentially limit diurnal heating.
Thursday night through Sunday...
Look for the frontal boundary to push out of the area Thursday night
with high pressure building in. Increasing large scale subsidence
and cold air advection will provide quiet weather through the
weekend. Temperatures are likely going to remain cooler than normal
with upper troughing over the eastern CONUS. Highs should generally
range from the mid 70s to low 80s. Much more comfortable dewpoints
in the 50s to low 60s by Friday will feel very pleasant compared to
the hot and humid conditions early this week.
&&
.AVIATION (00Z TAF Issuance)...
Issued at 627 PM EDT Mon Jul 28 2025
Impacts:
- Potential for sub-MVFR visibilities from fog predawn through
daybreak Tuesday
Discussion:
A line of convection has coalesced south of the terminals across
south central Indiana and will continue moving away to the
southeast. A few showers remain possible through near sunset but
coverage will be sparse with no mention needed in the forecast.
Mainly clear skies are expected overnight with winds going near
calm. With an abundance of moisture in the near surface layer...
fog is likely to develop late tonight through daybreak Tuesday.
Fog will diminish quickly with mostly sunny skies expected Tuesday
as high pressure and ridging aloft expands into the region. Winds
will be variable in direction at less than 10kts.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 8 PM EDT Tuesday for INZ021-028>031-035>049-
051>057-060>065-067>072.
&&
$$
UPDATE...Eckhoff
SHORT TERM...Melo
LONG TERM...Melo
AVIATION...Ryan
Source:
IND issues Area Forecast Discussion (AFD) at Jul 28, 10:03 PM EDT---------------
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