Area Forecast Discussion

KEY MESSAGES

- Breezy today with gusts in the 30 to 40 mph range this afternoon

- Scattered showers and thunderstorms tonight into Wednesday

- Rain chances again Friday into Saturday and early next week

- Above normal temperatures through early next week

FORECAST UPDATE

Issued at 920 AM EDT Tue Apr 21 2026

The forecast remains in good shape with only minor adjustments made. Latest surface analysis depicts surface high pressure centered near the Mid-Atlantic while surface ridging extends into the Ohio Valley. This will provide quiet weather through the day. That said, windy conditions are expected into the afternoon hours due to a strengthening MSLP gradient between the surface high and an approaching weak low pressure system from the northwest. Increasing diurnal mixing will also help promote stronger southwesterly gusts up to 35 mph. A few gusts near 40 mph cannot be ruled out. Look for southwesterly flow to warm temperatures well into the 70s.

DISCUSSION (Today through Monday)

Issued at 237 AM EDT Tue Apr 21 2026

Today...

Breezy conditions are expected today across central Indiana. A relatively tight pressure gradient between high pressure to the southeast and low pressure to the northwest will increase sustained winds. At the same time, mixing will tap into some stronger winds aloft. This will produce gusts into the 30 to 35 mph range, with some gusts near 40 mph possible.

The mixing will also bring dewpoints down, even with moisture trying to advect in from the southwest. Went closer to the 25th percentile of guidance for dewpoints this afternoon. Minimum humidity will be in the 20 to 30 percent range. Fortunately, fuels are moist enough that no significant fire danger is expected.

The gusty southwest winds combined with sunshine (filtering through high clouds at times) will boost temperatures into the middle 70s for highs.

Convection forming north of central Indiana should remain north of the area through the day.

Tonight through Thursday...

An upper wave and a cold front will be the forcing for the thunderstorms that develop during the afternoon. Forcing will move ahead of the cold front, allowing some convection to move south into central Indiana tonight. Moisture isn't great, and surface dewpoints will only be in the 40s and 50s.

Thus, instability doesn't look great for the convection. Shear isn't good either. However, stronger winds won't be far off the ground, with 40 plus knots starting about 3000ft off the ground per forecast soundings. With an inverted V sounding, wouldn't be surprised if a few storms have 40-50mph gusts, with a very low chance for a severe gust. Small hail is also possible.

With the limited moisture, feel coverage will be more scattered than numerous. Kept PoPs below the likely category.

The surface front will briefly stall out in the vicinity Wednesday before returning north. With little upper support, just kept some low PoPs around during Wednesday. Brief upper ridging will build in for Thursday, providing dry conditions.

Depending on where the front ends up Wednesday, there could be some clouds/fog around in the morning.

Highs will remain warm, reaching around 80 by Thursday.

Friday and beyond...

Upper energy coming out of an upper trough to the west will work with a cold front to bring some showers and thunderstorms on Friday. Weak forcing could keep lower coverage of rain on Saturday. Ridging will bring dry conditions Sunday, but rain could return early next week with another stronger upper trough. Temperatures look to remain above normal.

However, confidence remains low for Saturday into early next week with guidance differing on the details of how things will evolve.

AVIATION (12Z TAF Issuance)

Issued at 627 AM EDT Tue Apr 21 2026

Impacts:

- Marginal LLWS at all terminals continues this morning - Southwest wind gusts 25-30kt this afternoon - Scattered convection this evening into the overnight

Discussion:

Marginal LLWS conditions early will end as mixing kicks in during the day, and this mixing will allow for gusty winds up to 30kt or so. Gustiness will diminish early evening, but LLWS should return overnight tonight.

Outside of any convection, VFR conditions are expected. High clouds at times will give way to mid clouds late day into the night. Scattered convection will move in from the north mainly after 00Z Wednesday, and these will spread south through the night.

IND WATCHES / WARNINGS / ADVISORIES

None.