textproduct: Indianapolis

KEY MESSAGES

- Light rain and drizzle to continue at times through tomorrow

- Warmer than normal temperatures continue through Tuesday

- Rain chances return Tuesday night with a few rumbles of thunder possible

- Cooler but still near seasonal normals late week into the weekend

FORECAST UPDATE

Issued at 850 PM EST Sun Nov 1 2026

Moisture will continue to advect into central Indian over the next 12-24 hours slowly saturating the lower levels of the troposphere. Saturation has already starting over SW portions of the area where weak confluence has allowed for slightly greater upward motion with mid level rainfall processes leading to lower level saturation. This will be the primary area of concern for fog and drizzle development tonight as an already saturated layer becomese condensed beneath weak subsidence.

For the remainder of the area, patchy drizzle and decreasing cloud depth is expected. Drizzle may become heavy enough at times Monday morning for slight reductions is visibility (4-6SM), but otherwise not impacts are expected.

DISCUSSION (This evening through Sunday)

Issued at 130 PM EST Sun Nov 1 2026

Overview.

A quiet start to the week will give way to an active and significantly warmer pattern by Tuesday. Sprinkles and light rain showers will continue intermittently through tomorrow. As high pressure shifts eastward, much warmer air will surge north into the region Tuesday. A strong low pressure system will track across the Midwest on Tuesday night, bringing widespread rain, gusty winds, and the potential for a few thunderstorms. Behind this system, much colder and drier air will sweep in for Thursday with temperatures closer to normal through the weekend.

Tonight through Monday Night.

Surface high pressure centered across the upper Ohio Valley and central Appalachians will continue shifting east off the Mid- Atlantic coast tonight. Aloft, quasi-zonal flow transitions to weak southwesterly flow downstream of an upper-level shortwave crossing the Upper Mississippi Valley. Warm air advection intensifies across the lower Ohio Valley after midnight as an 850mb low-level jet ramps up to 25 to 35 kt. Additional saturation in the lower levels is expected to continue through the overnight with saturation currently at around 700mb which should then saturate to near the surface by Monday morning. The cloud deck should be shallow by Monday morning which will increase the chance that the weak isentropic lift could bring precipitation to the surface.

Scattered showers will continue across the forecast area through Monday morning before large-scale isentropic ascent shifts eastward into Ohio by early afternoon. A weak, diffuse surface warm front will attempt to advance northward toward the Ohio River, but persistent overcast conditions, weak low-level easterly to southeasterly flow, and rain-cooled air will reinforce a wedge of cooler air across central Indiana. This will limit daytime insolation, keeping afternoon temperatures capped in the mid-50s north to lower 60s south. For Monday night, mid-level forcing diminishes behind the departing northern-stream impulse. However, residual boundary-layer moisture beneath a low-level inversion around 900mb will maintain widespread stratus and the potential for some drizzle. Weak warm advection continues just above the surface, keeping overnight lows mild and well above seasonal normals, generally settling in the upper 40s to lower 50s.

Tuesday through Sunday.

Tuesday will initially feature a brief synoptic lull as an expansive upper-level ridge axis temporarily builds over the eastern third of the CONUS in response to a deep, amplifying longwave trough over the western United States. Central Indiana will reside firmly within the warm sector as the surface warm front lifts north into the lower Great Lakes. Southerly boundary-layer flow will transport 850mb temperatures of +10C to +12C into the region, pushing surface highs into the mid to upper 70s. Aside from isolated showers driven by weak warm advection, large-scale subsidence should keep the majority of the daylight hours dry beneath broken cloud cover.

The primary focus centers on the evening and overnight hours as the western trough rounds its base, acquires a neutral to slightly negative tilt, and ejects into the Mid- Mississippi Valley. Deterministic solutions from the GFS, ECMWF, along with their respective ensembles, remain in good agreement regarding a rapidly deepening surface cyclone tracking from northern Missouri northeastward across Illinois into the western Great Lakes. Kinematic fields associated with this system are exceptionally potent. An intense 850mb LLJ of 55 to 65 kt will overspread Indiana Wednesday afternoon and evening, accompanied by a 90 to 100 kt mid- level jet streak overhead. Bulk shear vectors in the 0-6 km layer will exceed 60 to 70 kt, oriented largely parallel to the advancing surface cold front, while 0-1 km bulk shear climbs to 35 to 45 kt.

All these favorable dynamics will be countered by an increasingly hostile thermodynamic field with very poor lapse rates and little to no instability. Model soundings show little to no instability except for the far southwestern counties and with the poor timing of an overnight passage of the front, severe weather looks increasingly unlikely with a HSLC event not really in play anymore. Models have a much better handle on the timing with little difference in the ensembles which boosts confidence in the decreased severe threat. Outside of the rain chances, the strong low level wind fields will help to bring breezy conditions with a few gusts up to 30 mph at times. There may be a few showers that linger into Wednesday, but expect chances to fall off quickly as slightly cooler air works into the area.

For Friday through Sunday, broad cyclonic flow aloft will encompass the Great Lakes and Northeast. Several weak vorticity filaments rotating through the base of the longwave trough will sustain intervals of cloudiness and isolated rain Friday and early Saturday, particularly across north-central and northeast portions of the area. A sprawling Canadian surface high will build southeastward across the mid-Mississippi and Ohio Valleys late Saturday into Sunday, allowing winds to diminish and skies to clear. Temperatures will drop to near normal with highs in the upper 50s to low 60s and overnight lows in the upper 30s.

AVIATION (06Z TAF Issuance)

Issued at 1220 AM EST Mon Nov 2 2026

Impacts:

- MVFR conditions likely deteriorating for a time to IFR in drizzle and some patchy fog overnight into midday Monday

Discussion:

Low level moisture coupled with weak forcing from a departing upper level wave will likely produce areas of drizzle at times through at least midday Monday, which will produce deteriorating conditions, with widespread MVFR likely dropping into the IFR category for several hours just after daybreak through midday or early afternoon. VFR appears set to return Monday evening. Visibility fluctuations are likely in both patchy fog and the aforementioned drizzle, with ceilings being the more consistent variable.

Winds will generally be between 140-170 degrees during the period around 7-10KT.

IND WATCHES/WARNINGS/ADVISORIES

None.