textproduct: Indianapolis

KEY MESSAGES

- Light rain and drizzle continuing through the early morning hours before drying out this afternoon

- Well above normal temperatures from today into the weekend...with rain/fog expected Wednesday night

- Transition back to colder conditions through late weekend/early next week

SHORT TERM (Today and tonight)

Issued at 314 AM EST Tue Dec 23 2025

Main focus for the short term period will be tracking a combination of light rain and drizzle through the early morning hours across the Ohio Valley. Latest satellite imagery shows widespread stratus stretching from the Gulf Coast northward toward the I-70 corridor collocated with a strong 35-40 kt low level jet advecting low level moisture northward. Local soundings around the region show a strong inversion almost 2km agl associated with warm air advection aloft. This inversion is keeping the copious amount of Gulf moisture trapped within the boundary layer resulting in the widespread stratus and rapidly rising humidity levels. Subtle waves aloft are providing just enough lift to squeeze out light showers and drizzle under the low stratus, with the greatest chance for any light precipitation along and south of the I-70 corridor through the early morning hours.

The main forecast challenge for the rest of the day will be determining how quick low stratus lifts and breaks up over portions of the state. Deeper moisture across South Central Indiana may hold on longer than what some guidance suggests as the sun angle is at its lowest point of the year and solar heating is at its weakest. A frontal boundary does push in from the north through the day advecting in drier air from west and northwest. This drier air can already be seen on Satellite imagery with a sharp cut off from low stratus to clear skies over Illinois. Expect Northwest and North Central Indiana to clear out first as the front nears this afternoon, with clouds holding on longer further south where drier air may take longer to reach.

Despite some areas remaining cloudy, the warmer airmass in place ahead of the front should still support high temperatures well above average for this time of year in the 50s and potentially 60s in areas that clear out quicker before the frontal passage. West southwest winds ahead of the front may gust 20-25 mph at times, especially in areas where more sunshine is observed leading to better low level mixing.

High pressure moves across the Great Lakes region tonight clearing out much of the state and weakening the pressure gradient. Lighter winds and clearing skies will allow temperatures to plummet later tonight. There is not much cold air incoming with this area of high pressure; however radiational cooling will result in a strong nocturnal inversion setting up as the surface drops to the upper 20s to mid 30s while 925mb temperatures near 50F. Any cloud cover stubborn to clear out over southern and southwest Indiana will help keep temperatures from falling near the freezing mark. Have a sharp north to south temperature gradient south of I-70 for tonight with better chances for temperatures to reach the freezing mark near I-70 and points north while cloudier areas further south remain in the mid 30s to near 40.

LONG TERM (Wednesday through Monday)

Issued at 314 AM EST Tue Dec 23 2025

Wednesday through Saturday...

The middle of the week will maintain well above normal temperatures, albeit with less confidence in 60-degree readings for most of central Indiana...as weakness riding the parent upper ridge likely cross the region, often dragging a stationary/cold frontal zone in a WNW-ESE proximity over the Midwest. Resultant conditions will feature often considerable cloudiness, light/moderate breezes whose heading will depend on if a weak circulation is approaching/departing, as well if the southern extents of chilly Canadian high pressure are trying to build into the region for a few hours. Rain showers/fog will be most likely Wednesday night with low pressure scheduled to cross Indiana, with light amounts expected and low confidence for any location. High certainty in Christmas Day continuing above normal temperatures, but now with lighter northeast breezes holding low 60s most likely to southern portions of the region.

Late week to potentially trend more unseasonable assuming next transient low pressure riding the broad subtropical ridge, passing west to east, tracks near/north of the CWA. The overall retracted upper flow will combine with heights eventually plunging down the Pacific coast to support a quasi-split flow...with stronger low pressure well to our north and a weaker circulations or two closer to the I-70 corridor. Overall gradient should allow for occasionally stronger southwest winds that could advect widespread 60s to the region, with possible mid to upper 50s dewpoints bringing a feel of springtime humidity. Occasional showers are also on the table, especially in the 12 hours ahead of a passing wave.

Sunday and Monday...

Strengthening cold frontal zone to cross Midwest around the middle of the weekend...ahead of plunging polar air mass that is progged to amplify H500 trough over eastern CONUS. Core of corresponding bitter cold to cross Great Lakes/Northeast, with central Indiana set- up for a couple nights in the teens early next week, and most likely a sub-freezing daytime to end the period. Associated winds should be reasonable for a 30-degree change, with robust to potentially gusty conditions around the end of the weekend...and lighter breezes favoring single digit overnight wind chills early next week.

AVIATION (06Z TAF Issuance)

Issued at 1252 AM EST Tue Dec 23 2025

Impacts:

- Ceilings lowering to IFR levels through the night with DZ increasing

- Combination of DZ and BR bring IFR vsbys at times overnight

- LLWS 250/40kt decreasing by sunrise

Discussion:

Patchy IFR ceilings are already in the area, and are expected to continue to lower some through the overnight hours. Based on upstream observations this evening, larger low level dew point depressions have kept cigs above IFR levels and vis largely MVFR to VFR. TIDS 0.3 deg reflectivity shows shallow showers and areas of drizzle already developing overhead as a 35-40 kt low level jet continues to advect low level moisture in the area. Went more optimistic for both cigs and vis overnight based on observations and trends this evening, however there is still a small threat for brief periods of IFR/LIFR cigs and vis at times.

Conditions will slowly improve later this morning, with the potential for VFR returning to most sites Tuesday afternoon.

Non-convective LLWS from a weakening 35-40 kt southwesterly low level jet overhead will continue over the next several hours. The strongest winds within the LLJ weaken and push eastward after 09z- 12z.

IND WATCHES/WARNINGS/ADVISORIES

None.