textproduct: Indianapolis

KEY MESSAGES

- Widespread dense fog this morning. A Dense Fog Advisory is in effect until 10am.

- Ice Jam development remains a concern this week...as temperatures continue to moderate through 50s to around 60 by middle of next week

- Wind gusts up to 35 mph possible Wednesday

- More active pattern returns for the second half of the week with rain and storm chances at times. Low precipitation chances linger into the weekend.

SHORT TERM (Today and tonight)

Issued at 307 AM EST Mon Feb 16 2026

Fog has rapidly developed overnight as expected, with most locations now reporting fog. Numerous rural areas are reporting dense fog as well. Dense fog will continue to expand through the morning hours. Therefore, we've expanded the Dense Fog Advisory to cover the remainder of our CWA until 15z.

Temperatures have been running below guidance as well, and we've lowered forecast lows this morning. Places that have fog have been the coldest, with readings into the low 30s. Temperatures should level off once fog takes hold. Outside of foggy areas, expect a gradual cooling until fog develops.

Fog may linger well into the morning hours, simply due to its extent and high cloud cover arriving aloft. The introduction of high clouds may limit diurnal mixing early, allowing fog to persist. However, the fog is expected to diminish by late morning or early afternoon. Cirrus should be thin enough to allow for boundary layer mixing in the afternoon.

Mixing will also promote increased southwesterly winds as a low- level jet builds in from the west. The low-level jet peaks during the afternoon between 20-30kt at 850mb. Surface winds increasing to about 10-15kt with a few gusts to 20kt are expected this afternoon, assuming less than perfect diurnal mixing (due to high cloud cover). Warm air advection will coincide with the onset of the low-level jet, with 850mb temps rising as much as 5C by the afternoon. Modest boundary layer mixing should lead to a rather warm day with highs in the mid to upper 50s. A few locations, especially further west, may push 60 degrees today.

Guidance is in decent agreement showing high cloud cover thinning a bit this evening. This may allow temperatures to cool off quickly after sunset, especially if winds diminish below 5kt. This may not happen for the northwestern half of the CWA, where the MSLP gradient remains tight enough to promote at least some wind. Further southeast, less of a gradient and terrain should allow winds to become light and variable at times. We went cooler than guidance for low temps in these locations and introduced patchy fog to the forecast. Fog is not expected to be as widespread as it is right now because high cloud cover should not completely clear.

LONG TERM (Tuesday through Sunday)

Issued at 307 AM EST Mon Feb 16 2026

Tuesday through Wednesday...

Mostly quiet weather is expected at the start of the extended as upper ridging remains overhead. Temperatures will trend warmer through midweek due to increasing S/SW flow and warm air advection from a warm front lifting north late Tuesday into Wednesday. This will support the warmest temperatures Wednesday which are likely going to reach or break the previous daily records. The current forecasted low Tuesday night into Wednesday morning is 53F which would break the daily record warmest low of 46F back in 1981. The current forecasted high for Wednesday in Indianapolis is 68F while the daily record high is 66F.

Guidance depicts the low pressure system associated with the warm front passing northwest of central Indiana through the Great Lakes Region. At least modest mid-upper level forcing from the parent trough and warm air advection ahead of the broad but strong surface low to the northwest will support scattered light showers late Tuesday night into Wednesday morning. These showers should diminish by Wednesday afternoon once forcing shifts further east. A strengthening MSLP gradient combined with diurnal mixing into a strong LLJ will likely promote windy conditions Wednesday. Look for wind gusts as high as 35 mph.

Wednesday night through the weekend...

A negatively tilted shortwave trough aloft is expected to promote strong surface cyclogenesis near the Central Plains late Wednesday night into Thursday morning. Guidance then depicts the low pressure system lifting northeastward towards the region. This will likely support precipitation, but exact details remain uncertain due to varying solutions of the surface low track and evolution.

Guidance does generally suggest low level theta-e advection promoting modest instability Thursday afternoon through the early overnight hours. This supports the potential for isolated to scattered thunderstorms, particularly for southwest portions of the area. A few of these storms could be severe given the modest instability and favorable kinematics from the dynamic system, but again uncertainty remains in the forecast. The thermodynamic environment and how much instability will be in place remains the greater uncertainty. These details should become clearer in the coming days though.

Highs are expected to be in the 60s once again Thursday thanks to additional warm air advection ahead of the aforementioned system. Look for temperatures to then trend cooler into the weekend as ensemble solutions generally show decreasing heights aloft with upper troughing persisting across the eastern CONUS. Additional shortwaves passing through the region will keep low precipitation chances in the forecast into the weekend, but confidence in exact details is very low due to diverging model solutions.

AVIATION (12Z TAF Issuance)

Issued at 630 AM EST Mon Feb 16 2026

Impacts:

- Widespread dense fog this morning producing LIFR or worse conditions

- SSW wind gusts to 20kt this afternoon

- Patchy fog and low stratus possible tonight into Tuesday

Discussion:

Widespread dense fog has developed with visibility as low as 1/8 of a mile. LIFR of worse conditions will continue into the morning hours with improvement after about 14z. IFR to MVFR conditions may then persist until 17z.

High clouds are expected to be present much of the day today, becoming BKN to OVC at times. Cirrus should thin later this evening, with relatively clear skies heading into tonight. This may lead to another period of fog overnight into Tuesday morning. Low stratus may develop as a result Tuesday morning.

Winds are expected to become south-southwesterly today while increasing to 10-15kt. A few gusts up to around 20kt are possible during the afternoon hours.

IND WATCHES/WARNINGS/ADVISORIES

Dense Fog Advisory until 10 AM EST this morning for INZ021- 028>031-035>049-051>057-060>065-067>072.