textproduct: Indianapolis

KEY MESSAGES

- Very warm through Tuesday with highs in the mid to upper 80s

- Scattered severe storms possible both Monday and Tuesday with damaging winds, large hail and localized flooding

- Storms will end Wednesday as the front shifts south, but unsettled weather may return late week into next weekend

DISCUSSION (This evening through Sunday)

Issued at 226 PM EDT Sun May 17 2026

Surface Analysis early this afternoon shows low pressure over western KS. A warm front extended NE across IA to southern MI ahead of this low. Strong high pressure was found near the Carolinas. This was resulting in warmer southerly flow across Central Indiana, and temperatures were rising toward the lower 80s. Dewpoints were high also with this air mass, in the the 60s. Central Indiana was solidly in the warm sector.

Aloft water vapor shows a moderately amplified pattern over the CONUS with a deep trough over the Rockies and moderate ridging in place from the southeastern states through the Great Lakes to western Ontario. This was resulting in mainly a SW flow of warmer air across Indiana, arriving from the desert southwest. A short wave within this flow was found over WI, pushing NE and spreading shower over WI.

Convective temperatures have been reached as GOES19 shows widespread CU development across Central Indiana and radar remains quiet.

Tonight...

Quiet weather is expected tonight as Indiana will remain under the influence of the strong high pressure to the southeast, and remain in the warm sector. Forecast soundings overnight show a dry column, and afternoon CU will be lost as daytime heating diminishes. Look for decreasing clouds this evening followed by mostly clear skies. High dewpoints are also in place. as dewpoints remain in the mid 60s, and a moderate pressure gradient remains in place overnight, overnight low temperatures will only fall to the mid and upper 60s.

Monday and Monday Night...

An even warmer day is expected on Monday along with high chances for showers and thunderstorms. Models how a short wave pushing through the upper flow along with some tropical southerly flow aloft. This in combination with daytime heating and warm and humid airmass suggests a good situation for afternoon convection. HRRR shows an area of thunderstorms poised to push across Central Indiana through the afternoon showing a significant cold pool temperature drop in its wake by later afternoon and early evening. Forecast soundings show attainable convective temperatures with CAPE values over 1600 J/KG. Given these elements, will aim for a dry morning but will include high chances for afternoon showers and storms. Some storms could be severe with straight line wind damage. Look for high temperatures in the middle 80s.

Showers and storms will exit the area on Monday night with only the far SE parts of Central possibly having lingering showers from 00Z- 01Z. Forecast soundings over night show dry air within the lower levels associated with a cold pool along with a return to southerly winds as the synoptic southerly, warm sector flow takes over. Lows on Monday night should be similar to the previous night, in the middle to upper 60s.

Tuesday...

More chances for severe weather will be in play on Tuesday afternoon and Tuesday night. Indiana will still be within the warm sector, as a wave within the SW flow aloft pushes from the plains toward the Ohio Valley. Again Forecast soundings show a favorable column for storms with CAPE over 1700 J/KG and moderate wind shear in place. A stronger cold front will also pushing also pushing across Indiana on Tuesday afternoon into Tuesday night, providing forcing. Ahead of the front, providing forcing will also be a moderate LLJ of 40-50 knts. Thus confidence is high for another round of showers and storms, again some of which could be severe, with damaging straight line winds as the main threat. The front is expected to reach near the Ohio river near 00Z, thus Tuesday night pops will be considerably lower, although clouds and very light stratiform showers or sprinkles will be possible in the wake of the front, particularly in southern parts of Central Indiana.

Wednesday through Sunday...

Wednesday...

Clouds will be lingering across the area on Wednesday morning in the wake of Tuesday night/s cold front. Forecast soundings show plentiful lower level saturation, but subsidence arrives through the day as high pressure builds to the northwest. This will overall lead to the arrival of dry weather through the afternoon and into the evening. Will keep any precip mentions contained to the morning hours. With the arrival of a cooler air mass, Highs in the upper 60s to around 70 are expected.

Thursday...Forecast soundings on Thursday remain dry as strong high pressure moves through the Great Lakes, providing a cooler and dry easterly surface flow across Central Indiana. Will continue a dry forecast and partly cloudy skies.

Friday...Chances for rain will return again on Friday afternoon into Friday Night. The previous surface high will have exited to the east, allowing a return flow of a warmer and more humid airmass. As the front passes, a weak wave will be pushing through the Great Lakes, and the cold front will sag across Indiana. These ingredients are enough to include some chances for showers and thunderstorms.

Saturday and Sunday...Models show mainly zonal flow in place aloft on Saturday and Sunday. Higher confidence for dry weather is present on Saturday as Friday's front departs and high pressure over the upper midwest begins to influence Indiana. This high looks to maintain control over Indiana on Saturday into Sunday. However, winds become more southerly on Sunday allowing a bit more moisture to arrive. Early Forecast soundings show an inverted V sounding with afternoon CAPE over 1500 J/KG. Given this, afternoon diurnal convection cannot be ruled out and pops will need to be included. Temperatures on Saturday will be in the 70s, with warmer highs around 80 on Sunday.

AVIATION (00Z TAF Issuance)

Issued at 715 PM EDT Sun May 17 2026

Impacts:

- Southerly wind gusts between 20-25 kt quickly diminishing after 00Z today

- LLWS developing after 05Z lasting until sunrise Monday, greatest chance near HUF/LAF

- Gusty winds between 20-30 kt expected on Monday

- Scattered to numerous thunderstorms with MVFR vis moving into central Indiana during Monday afternoon.

Discussion:

Southerly wind gusts between 20-25 kt are expected to quickly diminish after 00Z with the loss of daytime heating.

Overnight, winds will increase between 005 and 020 as a low level jet develops ahead of convection over the Plains. With surface winds remaining between 4-8 kts beneath an inversion centered around 005, conditions are favorable for lower end LLWS conditions as winds will be 35-40 kts from 010-020. These LLWS conditions are expected to develop after midnight and end around sunrise.

Strong winds aloft will mix to the surface fairly quickly tomorrow morning despite increasing mid-high cloud cover, with gusts between 20-30 kt from the S-SW developing by 14Z. Convective line over the Central Plains is expected to push eastward to the MS valley by mid morning and into central IN by afternoon. Still some uncertainty on exact timing and intensity, but confident enough to warrant TEMPO wording of -TSRA at all sites during the afternoon.

IND WATCHES/WARNINGS/ADVISORIES

None.