textproduct: Indianapolis

KEY MESSAGES

- Near daily rain and occasional thunderstorm chances this week into early next, with an additional 2 to 4 inches of rainfall likely through Saturday, will produce widespread minor to moderate flooding across central Indiana creeks and rivers.

- A few strong to severe storms possible into tonight generally south of I-70.

- Much warmer late week into next week, with near record warmth likely Friday and potentially early next week as well.

SHORT TERM (This evening through Thursday)

Issued at 323 PM EST Wed Mar 4 2026

Tonight through Thursday....

Surface frontal boundary extends along the Ohio River valley of southern Indiana just south of central Indiana. A weak-moderately unstable airmass exists across the region, with elevated MUCAPE values on the order of 500-1000 J/KG north of the front. A well defined MCV in the vicinity of STL has supported recent convective line development over the MS valley of Southern IL. This activity is expected to be maintained and strengthened as it rides along and just north of the surface frontal boundary into southern portions of central Indiana late this afternoon/early evening. With 30-40 kts of deep layer shear, updraft rotation will be sufficient for organized multicells and weak supercell structures. Mid level lapse rates are not overly steep (6.5-7 C/km) but sufficient to enhance the potential for marginally severe hail production. There is an outside chance of an isolated damaging wind gusts/tornado along the frontal boundary in far southern counties of central Indiana if sufficient surface based buoyancy can be realized.

An increasing 850mb jet impinging on stationary front over the central Plains/Ozarks along with an approaching mid level shortwave trough will lead to regeneration and increase in a large area of convection west of central Indiana later this evening moving into central Indiana overnight.

Recent rainfall of 2-4 inches has lead to fairly saturated grounds and rivers to rise into minor to moderate flooding generally along and south of I-70. Expectation is for additional 1-3 inches of rainfall to occur with these areas as multiple rounds of convection move through Thursday morning. Therefore a Flood watch has been issued through noon Thursday with the potential for minor low lying flooding and continued increase in river/creek flooding.

The mid level shortwave is expected to pass through central Indiana tomorrow afternoon. There is a chance for scattered TS development prior to frontal/shortwave trough passage.

Thursday Night and Friday...

The frontal boundary is expected to become stationary along the Ohio River valley Thursday night before lifting back northward as a warm front on Friday. Areas of fog and or showers will be possible late Thursday night early Friday prior to the warm frontal passage. However, TS coverage appears negligible with building mid level heights in the wake of the shortwave trough. As 850mb temps rise to +13-14C Friday with moderate SW low level flow aiding in mixing, expect temps to rise well into the 70s, with current record temps in jeopardy (Indy's record is 75 in 1973).

Friday night...

A fairly strong cold front will push east through the plains Friday evening before reaching the MS valley by 12Z Saturday. A fairly long and fast line of thunderstorms is expected ahead of this front, possible reaching the border of Indiana by 12Z Saturday. A marginal risk for severe weather seems more than appropriate considering the very warm/moist airmass and strong deep layer shear vectors in place.

LONG TERM (Thursday night through Wednesday)

Issued at 323 PM EST Wed Mar 4 2026

The wet pattern will dry out slightly on Saturday through Wednesday.

Saturday...

Models suggest a moderate trough over the the plains on Saturday morning within the upper levels. This feature will progress toward Indiana through the day. Within the lower levels, Indiana will start the day within the warm sector with a cold front to west poised to push across the state. Showers and Storm chances will be needed given the expected passage of the cold front as ample moisture and forcing will be available. Forecast soundings show pwats over 1 inch, thus confidence is high for rain.

Saturday Night through Monday...

Zonal flow aloft is expected during this time in the wake of the departed upper trough on Saturday. The departed upper trough will lead to subsidence building across the area on Sunday and into Monday. Model response to this with a elongated area of high pressure suggested to build from the southern plains. This system will bring dry and mild weather through this period. Forecast soundings through the period show a dry column. Southwest flow developing by Monday and Tuesday with allow for a warmer air to continue to arrive resulting in mild and warm spring like temperatures.

Tuesday and Wednesday...

Another cold front along with an area of low pressure is expected to settle across the Central Indiana on Tuesday afternoon through Wednesday. An upper trough is will be settling over the Rockies at that time, and this will eject some forcing dynamics toward Indiana as the front is present. Thus given these signals, pops will be needed, with slightly cooler temperatures.

AVIATION (18Z TAF Issuance)

Issued at 1246 PM EST Wed Mar 4 2026

Impacts:

- Widespread IFR-LIFR ceilings through the period at all but KBMG.

- Widespread showers with thunderstorms increasing late this afternoon through tonight including during the cargo ops at KIND.

- Additional thunderstorms possible Thursday afternoon.

Discussion:

Widespread fog has improved around central Indiana with visibilities now above 1 mile at all terminals. However, widespread LIFR ceilings continue at all but KBMG. These LIFR ceilings are expected to improve to IFR through the mid afternoon.

Attention then turns to increasing precipitation, showers and thunderstorms late this afternoon and overnight. It appears that several waves of thunderstorms will occur during the forecast period including during the cargo ops at KIND. Highest confidence on timing is with the initial wave late this afternoon, with lowering confidence on timing and location tonight. Have opted to use TEMPO and PROB30 wording in overnight into tomorrow period to account for these uncertainties.

IND WATCHES/WARNINGS/ADVISORIES

Flood Watch through Thursday morning for INZ043>049-051>057- 060>065-067>072.