textproduct: Indianapolis

KEY MESSAGES

- Hot and more humid Weather will be arriving through Tuesday.

- Thunderstorms will be possible late next week into the weekend.

FORECAST UPDATE

Issued at 944 AM EDT Sun Aug 30 2026

Latest satellite observations this morning depict extensive mid-high clouds across the northern half of Illinois and Indiana. These clouds are associated with an upper impulse traversing the region. There have been a few sprinkles reported at times across Illinois with moisture streaming in aloft and weak forcing from the impulse, but surface ridging and residual subsidence-induced dry air has mostly limited any measurable precipitation from reaching the ground.

Dry air in the low-levels will keep central Indiana mostly dry today, but low 20 percent rain chances were included in the latest updated for far north/northwestern counties today as the subtle upper level wave moves through. Mid to high clouds will limit daytime heating slightly, mainly across the northern half of the area. Southwesterly flow should still help promote a warming trend today with temperatures in the mid 80s to low 90s.

DISCUSSION (Today through Saturday)

Issued at 246 AM EDT Sun Aug 30 2026

Surface analysis early this morning shows high pressure east of the middle Atlantic States, allowing a warm and humid southerly flow across Central Indiana. Water vapor shows a stream of Pacific moisture pushing across the Rockies to a ridge axis over the upper midwest before spilling southeast across Indiana and the eastern Great Lakes. It was this stream of upper moisture that was providing mid and upper level cloud cover across Central Indiana and points north. HRRR profiles show plentiful dry air within the lower levels. Dew points were creeping higher, into the 60s.

Today and Tonight...

The models continue keep the stream of upper level Pacific moisture streaming across a ridge axis over the Great Lakes, as upper level high pressure remains parked over TN/AR. A thermal ridge within the lower levels is suggested to set up over the upper midwest, as warm air advection continues across Indiana. Surface high pressure to the east looks to continue to control our lower levels, providing warmer and more humid flow. Still, forecast soundings today and tonight suggest abundant dry air within the lower levels. Thus we will expect a warmer day with ongoing warm air advection along with passing mid to high clouds through tonight.

Monday and Tuesday...

Forecast soundings on both Monday and Tuesday continue to suggest plentiful dry air within the lower levels along with ongoing warm air advection still in place. 850mb temps are suggested to rise to around 22C, bringing very warm temperatures for early September. Convective temperatures in the 100s are suggested also, thus no CU. Within the upper levels the strong upper level high pressure system will begin to surge northeast somewhat, driving any forcing dynamics north, across the Great Lakes. Thus mostly clear skies will be expected with hot high temperatures in the 90s.

Wednesday through Thursday...

Confidence continues to be high for hot and humid weather at the end of this workweek continuing into next weekend.

The upper pattern on Wednesday into Thursday suggests strong upper level high pressure over the Tennessee and Ohio river valleys with the upper flow streaming across the Great Lakes with some embedded waves within that flow. A thermal ridge and frontal boundary looks to be draped across the Great Lakes at that time, keeping Indiana within the warm sector. Forecast soundings at this point show convective temperatures in the mid 90s, which can be reached. Steep lapse rates are also suggested, thus isolated diurnal convection cannot be ruled out either. However the main story will be September heat with highs in the low to mid 90s and high heat index values. Heat Advisories will be possible in the week ahead.

Friday and Saturday...

The ridging over the upper midwest is suggested to become sharper on by Friday and Saturday. This will allow for NW flow to develop across Central Indiana, also introducing a possible pattern of placing us on the periphery edge of a ring of fire. The previous warm front and thermal ridge to the north is suggested to sag southward across Indiana and this may cause an extra convection triggering feature. Forecast soundings suggest plentiful CAPE with steep lapse rates on Friday and Saturday. Thus pops day will continued to be needed. Caveats include the frontal boundary sagging south of Central Indiana on Saturday, resulting in cooler northerly flow while introducing subsidence within the column. Furthermore, possible clouds along the front may prevent max heating, keeping temperatures cooler. Overall, some pops should be included here with highs above seasonal normals.

AVIATION (12Z TAF Issuance)

Issued at 620 AM EDT Sun Aug 30 2026

Impacts:

- None; VFR expected.

Discussion:

Overall very little change in the ongoing forecast.

Mid and high level clouds will be expected to continue to stream across the TAF sites Today. Forecast soundings continue to show dry lower levels through the next 24-36 hours. Although there are some radar returns over northern IL and Northern Indiana, much of this is expected to stay north of the TAF sites or remain virga falling from high bases through dry lower levels.

Indiana will remain under the influence of high pressure in place over the northeastern states, resulting in warm and humid southerly flow within the lower levels today.

IND WATCHES/WARNINGS/ADVISORIES

None.