textproduct: Indianapolis

KEY MESSAGES

- Wet pattern through the week and into the weekend, with multiple rounds of showers and storms expected, which may produce occasionally heavy rainfall and renewed flooding along area waterways

- Potential for strong to severe storms at times, primarily late Thursday and again Saturday

- Strong non-thunderstorm winds expected Thursday and potentially Saturday, with frequent gusts of 35-40 MPH possible

- Drier and cooler weather for early next week

FORECAST UPDATE

Issued at 1006 AM EDT Wed Apr 1 2026

Wide ranging conditions expected across Indiana today as a cold front separates a warm and humid airmass to the south from a colder airmass to the north. Current observations indicate the quasi- stationary front stretches west to east just south of I-70. A 20+ degree temperature gradient exists on either side of the front with low 70s to the south and upper 40s in North Central Indiana. The main area of remains in North Central Indiana on the north side of the front where the best low to mid level frontogenetical forcing is located. IND ACARs soundings show a sharp boundary layer inversion with steep mid and upper level lapse rates above it, supporting embedded thunderstorms within the larger area of rain.

For the rest of the morning and early afternoon, expect the most widespread rain to persist in North Central Indiana. Satellite and radar depicts a weakening meso-low in Illinois, which may enhance coverage and intensity of rainfall north of I-70 through the early afternoon. This low will also work to spark off additional scattered convection just to the south of the main rain shield along the I-70 corridor. Convection in Central Indiana should be more intermittent until the next wave of showers and embedded storms in Missouri tracks along I-70 and into the state by early afternoon. Confidence is increasing that this next round of showers and storms will track further south than the convection early this morning. Best chance for more widespread showers and an embedded storm looks to be south of I-70. Best thunderstorm chances remain in the warm sector in South Central Indiana where the environment supports additional surface based storms. Along I-70 and in the Indy Metro area, mainly plain rain expected with a few lightning strikes possible early to mid afternoon; however CAMs shows decreasing instability in the mid levels later today lowering lightning probs overall north of the front.

SHORT TERM (Today through Friday night)

Issued at 328 AM EDT Wed Apr 1 2026

An active pattern remains the expectation for the remainder of the week, with multiple opportunities for showers and thunderstorms, with one or more at least low chances for a strong storm or two.

A frontal zone continues to sag into the region this morning, currently draped from near St. Louis to Indianapolis/Muncie and Columbus, Ohio. This boundary, in part reinforced by a rain cooled airmass to its north, will continue to sag southward during the day and should stall near the southern border of the forecast area later today before lifting back northward as a warm front tonight into Thursday.

Relatively weak elevated instability north of the boundary will put a cap on embedded thunder chances today, though modest surface based instability should develop south of the front, wherever it happens to stall, and this, combined with the frontal forcing, will likely produce at least some scattered thunderstorm activity. Deep layer shear is strong enough to support some storm organization, so an isolated strong storm is not out of the question, though this limited threat will likely be slightly more likely to our east.

The primary concern will be at least a minor hydrologic threat as flow is aligned to a significant degree, though not perfectly, boundary parallel, which could produce areas of training in a background setting featuring precipitable water values near or above climatological max.

A bit of a lull in rain chances can be expected late tonight into early Thursday as the area reemerges into the open warm sector with the warm front pushing rapidly northward in response to a strong surface low and upper level wave moving northeastward out of the central Plains into the upper Great Lakes.

The shower and thunderstorm threat will ramp back up again on Thursday afternoon into Thursday night as one or more rounds of prefrontal convection associated with the aforementioned system move through the region. Deep layer shear will remain plentiful, and low level shear will be substantial as well owing to strong low level flow and some veering in the warm advection regime. The degree of destabilization is in question giving the threat a somewhat conditional nature, but even modest instability in such a flow environment would pose at least a decent wind threat with minimal trouble mixing down 50+KT flow within a few thousand feet of the surface, as well as concern for a tornado or two.

Outside of thunderstorms, Thursday will again be quite windy, with PBL mixing and steep low level lapse rates likely able to mix down frequent gusts of 35-40 MPH with isolated higher gusts possible. Similar gusts may be possible on Saturday as well depending upon the depth of mixing.

This low will be followed in quick succession by another similarly strong system Friday into Saturday, which will hold up the front from fully pushing through the area until this second low passes Saturday. Despite continued strong deep layer shear, instability is an even larger question during this time frame, though at least an isolated strong to severe storm threat would appear possible then as well.

Throughout this period, deep moisture and the potential for repeated rounds of moderate to at times heavy rainfall will gradually increase the hydrologic concern across the region, and a localized flash flood threat may grow with time, and hydrologic ensembles show a fairly high likelihood of portions of the main stem rivers returning to at least minor flood, particularly along the Wabash, and portions of the lower White and East Fork White.

Temperatures will be well throughout the vast majority of the week, though a strong cross-boundary temperature gradient will exist today and tonight across central Indiana. Temperatures will frequently be 15-25 degrees above average until frontal passage this weekend.

LONG TERM (Saturday through Tuesday)

Issued at 328 AM EDT Wed Apr 1 2026

Saturday and Saturday Night...

Active weather looks to finally come to an end on Saturday and Saturday Night. As we being the day, models suggest ridging aloft over the eastern Great lakes departing, but a cut off low will be found over the upper midwest. This will place Central Indiana still within the SW flow aloft. The cut off low and an associated moderate upper trough will push toward and across Central Indiana, allowing plenty of upper support to arrive in Indiana through the day. Within the lower levels Central Indiana will start the day within the warm sector, and a cold front will push across the state through the afternoon and into the evening. Forecast soundings at this early stage suggest a deeply saturated column passing, with little CAPE, through the afternoon. Subsidence and drying is shown to arrive on Saturday night after 00Z. Thus confidence will be high along with high pops for Saturday at this time. Pops will need to be tapered off on Sunday night as the moisture exits and drying, subsidence and cold air advection arrives.

Sunday through Tuesday...

Quiet and cooler weather is expected on Sunday through Tuesday, as strong ridging is expected to take shape over the western CONUS. This will result lee side northwest flow to spill from Central Canada into the Ohio Valley on Sunday through Tuesday. Meanwhile at the surface strong high pressure is suggested to settle across the plains, resulting in a continued flow of cool and dry Canadian air across Central Indiana. On Monday, there is a caveat. Models show a weaker short wave within the NW flow aloft streaming across the Great Lakes. While this will provide some upper support, precipitation chances appear minimal as moisture sources are limited. Lower levels are suggested to remain dry as mid level clouds pass with this feature. Thus will keep a dry forecast at this time, but it will be something to watch over the next few runs to see if enough forcing could be present to squeeze out some very light precipitation. Otherwise, we will expect a few more clouds on Monday as these features pass.

More sunshine and cooler weather should arrive on Tuesday as ridging is expected to re-establish itself over the upper midwest, providing subsidence and dry air flowing into Indiana. Temperatures on Sunday through Tuesday will be at or below seasonal normals, thus highs mainly in the 50s.

AVIATION (18Z TAF Issuance)

Issued at 209 PM EDT Wed Apr 1 2026

Impacts:

- SCT TSRA near KBMG 18z-21z, then another chance for widely SCT TSRA at all sites 02-08z tonight

- MVFR to IFR cigs persist through tonight

- Winds becoming southerly and increase Thu AM, gusts to 35-40 kts possible Thu afternoon

Discussion:

A quasi-stationary boundary is currently draped across South Central Indiana this afternoon and will lift back north as a warm front overnight tonight. Continued MVFR to IFR cigs expected at all sites through tonight as low level moisture remains trapped under a stout inversion just above the surface. Satellite and radar imagery shows a line of thunderstorms developing along the boundary south of KBMG. These storms should pass just to the SE of KBMG, however it is possible a storm may pass within a few miles of the airport, so have added a TSRA threat through around 21z. Plain rain showers continue for KIND, KHUF, and KLAF for the next several hours with little to no lightning threat through this evening.

Tonight, the frontal boundary lifts northward, switching winds from northeasterly to southerly around or after sunrise tomorrow. Scattered showers and a few thunderstorms may develop overnight as the front moves northward; therefore have added a prob30 group for TSRA for all TAF sites. Highest confidence in storms is within the 02-08 timeframe. A few storms may be strong and produce small hail and lightning.

For tomorrow, deep mixing into a strong low level jet will promote southerly wind gusts over 45 mph after 15z. Strongest winds expected at KHUF, KIND, and KLAF. While tomorrow should be mainly cloudy, any sunshine and increased surface heating could lead to higher wind gusts locally.

IND WATCHES/WARNINGS/ADVISORIES

Wind Advisory from 11 AM to 7 PM EDT Thursday for INZ021-028>031- 035>041-043>048-051>056-060.