textproduct: Indianapolis

KEY MESSAGES

- Much Warmer Today. Chances for showers and thunderstorms today, especially across southern Central Indiana.

- Cooler and rainy on Tuesday.

- Largely below normal this upcoming week, with multiple chances for rain; heavy rain possible at times.

DISCUSSION (Today through Sunday)

Issued at 240 AM EDT Mon May 4 2026

Surface analysis early this morning shows strong high pressure in place across the southeastern states and FL. Deep low pressure was found over western Ontario. These two systems were combining to allow a mild southerly surface flow. Aloft, water vapor continued to show mainly NW flow in place across the upper midwest spilling down into Indiana. That flow was due to a deep upper low over Hudson Bay. Beneath that flow was a plume of Pacific moisture streaming across the Plains to KY and TN. Radar shows some storms developing on the northern edge of this plume over southern IL, while subsidence remained in place across Central Indiana.

Today and tonight...

Central Indiana will spend today and tonight within the warm sector as a weak upper short wave passes across Indiana within the flow aloft this afternoon. Warm air advection will be ongoing and the short wave should be able to tap the Pacific upper moisture that are resulting in some shra/tsra at that moment. Forecast soundings this afternoon suggest a favorable set-up for convection, showing deep saturation by mid afternoon. HRRR suggests scattered showers and isolated thunderstorms moving across Central Indiana, especially southern central Indiana, this afternoon as the forcing from the passing wave passes. Thus will trend pops a bit higher this afternoon across most of the southern 2/3rds of the forecast area. Ongoing warm air advection today should allow highs to reach the low to middle 70s with good mixing in play along with wind gusts to around 25-30 mph.

This evening, heating will be lost along with forcing as the short wave exits to the east. Little change will occur with the airmass, as winds will remain southerly through the night and a cold front begins to advance from the northwest. Lows tonight should be in the mid 50s.

Tuesday and Tuesday Night...

Higher confidence for more rain and cooler weather on Tuesday. A cold front will be slowly crossing Central Indiana through the course of the day starting in the northwest in the before reaching the southeast parts of Indiana by late afternoon. Forecast soundings during this time shows favorable column for convection. Models hint at overnight convection over the plains reaching Cenilder but still ltral Indiana by the afternoon. Thus with plenty of ingredients available, high pops will be used on Tuesday and Tuesday evening as these features pass. Brief heavy rain will be possible as pwats over 1 inch are expected. With clouds and rain expected on Tuesday, will trend highs only toward the upper 50s and lower 60s.

Wednesday and Wednesday Night...

A secondary short wave looks to pass on Wednesday as the nearly zonal flow remains in place. GFS continues to suggest a stream of mid level moisture available, streaming across Central Indiana while the ECMWF is a bit less aggressive. Within the lower levels, Tuesday's cold front will be well east of Indiana as the day progresses and high pressure is suggested to be building from the northwest with cooler northerly winds in place across Central Indiana. Forecast soundings suggest subsidence through the day. Thus confidence here is low and and will use some pops for the time being.

Thursday through Sunday...

Overall upper pattern remains unchanged during this period. Models suggest the predominate upper low remaining over eastern Canada, keeping the continued cyclonic flow in place aloft over much of the eastern 1/2 of the country including Indiana. This will keep a steady stream of below normal temperatures in place across Indiana from Thursday through the weekend. Meanwhile at the surface, a series of weak highs and lows will look to pass. High pressure is expected to push across the area on THursday, before a weak trough passes on Friday. Another high arrives for Saturday followed by a slightly more organized low on Sunday. Given the cyclonic flow in place aloft, and forecast soundings suggest cold air aloft with steep lapse rates available each day, daily convection cannot be ruled out and for the moment, additional support appears available on Friday and Sunday. Thus daily chances for rain will be expected in the forecast, however, this will be mainly due to daily diurnal chances and the passing of the trough and low on Friday and Sunday respectively. Overall, high confidence periodic showers during this period, but low confidence on specific timing.

Given the cool, NW flow, temperatures will remain at or below seasonal normals.

AVIATION (06Z TAF Issuance)

Issued at 1257 AM EDT Mon May 4 2026

Impacts:

- Mainly VFR; Brief MVFR possible with showers or storms after 18Z.

Discussion:

Mainly VFR conditions should prevail through the period.

Overnight, clear skies will remain in place over the Taf sites, but on Tuesday as the upper flow changes, more moisture will begin to arrive aloft on westerly winds. This will result in chances for scattered showers and storms during the afternoon as forecast soundings suggest a favorable column for convection within the warm sector in place over Central Indiana. HRRR shows scattered showers and storms across Central Indiana during the afternoon and evening hours. Low confidence for precise timing, thus a large VCTS/VCSH window was used. Any TSRA that strikes a Taf site could produce brief MVFR conditions.

IND WATCHES/WARNINGS/ADVISORIES

None.