textproduct: Indianapolis

KEY MESSAGES

- Multiple rounds of thunderstorms expected today, severe weather is possible this afternoon into tonight.

- Isolated Showers and thunderstorms possible on Tuesday, mainly across southern Indiana.

- Cooler temperatures expected Wednesday through Sunday.

DISCUSSION (This evening through Monday)

Issued at 158 PM EDT Mon Apr 27 2026

Surface analysis late early this morning shows deepening low pressure over IA and MN, with a cold front extending south across IA to Central MO and NE OK. An area of strong convection had developed within the warm sector, over IL and was pushing east toward Indiana. Cloud tops continue to show steady state or slightly cooling tops. However the strongest echos were now pushing into a more stable area of air as showers have been falling in the Wabash Valley. Expected progression of the storms will be to the east, but conditions across Indiana were less favorable for convection. A better area for storms was found across southern Central Indiana with more access to instability there. Aloft, water vapor shows a moderate short wave over the Dakotas with a southwest flow of air ahead of this wave spreading across Illinois and Indiana amid weak diffluence aloft.

Tonight...

SEVERE WEATHER THREAT REMAINS TONIGHT.

Models show the upper wave progressing across the region, continuing to spread forcing dynamics across Indiana through the evening, Caveats have come into play. Namely, the cloud cover across Central Indiana from convection upstream have not allowed for peak heating. CAPE across the area remains limited this afternoon and the convection is expected to spread across Indiana in a decaying state late this afternoon. This will further diminish our severe weather threat. Later this evening, HRRR suggests more development over southern Illinois, pushing east into SW central Indiana. Confidence is higher for these storms to be strong to severe, perhaps impacting Vincennes, Sullivan, Linton, Washington and Shoals. Damaging straight line winds will continue to be the main threat, again an isolated QLCS tornado.

After a rainy evening, upper forcing is shown to end toward 05Z. Forecast soundings show drying and subsidence as the upper trough axis exits to the northeast. Lower level cloud cover should remain through the night, as lower level moisture remains trapped underneath an inversion.

Thus overall, high confidence for rain and storms this evening, with best chances across the southern and southwest parts of the forecast area. This will be followed by cloudy skies tonight. Little overall change in the air mass will result in lows only in the upper 50s as dew points are expected to remain in the 50s.

Tuesday...

Dry weather is expected on Tuesday as the upper flow is nearly zonal, with little in the way of forcing dynamics passing across Indiana. Forecast soundings continue to show a dry column with subsidence ongoing with the departure of the previous wave. At the surface, high pressure over the northern plains will continue to spill southeast toward Indiana. Thus after morning clouds, some afternoon sunshine should become available. Highs will reach the upper 60s to around 70.

Tuesday Night and Wednesday...

Showers and Thunderstorms will be expected during this time, particularly on late Tuesday Night into Wednesday. Models show another subtle short wave within the broader cyclonic flow aloft pushing across our region on late Tuesday night into Wednesday. A weak area of surface low pressure is expected to ride this wave, pushing across KY, and placing Indiana on the NW side of the low. Forecast soundings show the arrival of deep saturation late Tuesday Night into Wednesday with pwats as high as 1.7 inches. Thus confidence is high for another round of rain showers on at this time. Rain showers will exit by Wednesday afternoon as the upper forcing and surface low departs. northerly surface winds in the wake of the this system will allow for cooler temperatures on Wednesday, with highs only in the lower to middle 60s.

Thursday Through Monday...

Indiana/s weather during this period will be controlled mainly by a strong area of upper level low pressure over Ontario and Quebec. This feature is suggested to rotate waves within this flow across Indiana, mainly on Friday and again on Monday. The upper flow during this time will be mainly a northwest fetch spilling toward Indiana from Central Canada, providing mainly dry and cool air, due to the low to the northwest. It is only when the weak waves pass that enough forcing will be present to result in shower or storm chances.

Through this period within the lower levels surface high pressure looks to be anchored over the plains states, keeping mainly westerly or northwesterly flow in place across Indiana. Models suggest a poorly organized cold front to pass on Friday, but this system lacks access to deeper gulf moisture. A weak area of low pressure is suggested to pass across Indiana on Monday, again associated with the upper level feature.

Thus will try to contain pop chances to just Friday and Monday, with mainly dry and cool weather expected on Thursday, Saturday and Sunday.

As no intrusions of arctic or tropical air are expected, look for temperatures to be near or below typical seasonal lows.

AVIATION (18Z TAF Issuance)

Issued at 140 PM EDT Mon Apr 27 2026

Impacts:

- S-SE wind gusts 20 to 30 kt with higher gusts in TSRA - Scattered to numerous thunderstorms through 04Z - LLWS around 45kt Monday evening/night - MVFR ceilings Monday evening into early Tuesday

Discussion:

Scattered showers have already developed across western Indiana. A line of thunderstorms over IL will shift eastward across all but KLAF this afternoon. IFR vis is expected with this convection along with a wind shift to the W-NW and gusts from 35-45 kts, lasting less than 1 hr at all the terminals. In the wake of this line, rain showers with embedded TS is expected for several hours, before another round of TSRA moves into the region after 23Z. This second round of TS activity is expected to end between 03-05Z from west to east as the cold front pushes eastward with an associated surface wind shift to the west. MVFR ceilings will linger until Tuesday morning behind the front.

IND WATCHES/WARNINGS/ADVISORIES

None.