textproduct: Indianapolis

KEY MESSAGES

- A period of light snow this evening into the early overnight with light accumulations possible mainly across the northern half of central Indiana

- Bitterly cold temperatures and gusty W/NW winds will produce wind chills as low as -15 at times Monday and Monday night

FORECAST UPDATE

Issued at 915 PM EST Sun Jan 18 2026

Broad lift ahead of an approaching frontal boundary has led to widepsread snow across most of central, as previously expected. There is some evaporatively cooling across northern portions of the region, where lift is greatest, leading to better low level saturation and snow rates as of 02Z. Currently seeing many areas north of I-70 with visibility in the 1 to 3 mile range.

Given low level temperatures in the teens with good cooling aloft, snow ratios should be rather effeciient tonight somewhere in the 18- 22:1 range. This in combination with 0.01-0.04" of QPF over the next few hours will lead to light accumulations of 0.1-0.8", greatest amounts in the Lafayette to Kokomo area. Latest guidance has this trough pushing a little south of east, of which will likely lead to a QPF gradient near and north of the I-74 corridor when the primary snowfall stops sometime between 2 and 4 AM. Although the frontal passage will usher drier near surface air, cyclonic, cold flow aloft within a stable stratus layer should lead to continued flurries and potentially light accumulating showers over northern central Indiana into the morning hours.

The other item of note tonight will be the increase in winds as the pressure gradient increases and dry, cold air remains slightly upstable leading to strong wind gusts of 30-35 MPH. This will also be attached with air temperatures in the single digits pushing apparent temperatures well below zero, between -10 and -20 across a majority of the CWA.

SHORT TERM (This Evening through Monday)

Issued at 310 PM EST Sun Jan 18 2026

Stratus has been gradually mixing out from the southwest this afternoon but mid and high clouds are quickly arriving from the west. Temperatures have struggled to rise all day with upper teens and lower 20s as of 19Z.

Two primary issues serve as the focus for the short term through late Monday. The first involves the potential for light snow accumulations this evening into the early overnight as a potent mid level vort lobe pivots across the region in advance of a cold front that will pass through overnight. The second comes in the wake of the frontal passage as bitterly cold air and gusty W/NW winds bring subzero wind chills into central Indiana late tonight through Monday.

Filtered sunshine will continue for a couple hours mainly south of I- 70 before the mid and high level clouds overspread the area by late day. The snow is currently across the upper Mississippi Valley and will quickly shift southeast over the next few hours arriving in the northern Wabash Valley early this evening then pivoting E/SE across the region. Recent model guidance suggesting the upper level wave will dig further south than previously thought and obs/radar data to our northwest supports that thinking. Have expanded the light snow coverage over most of the forecast area this evening with the steadiest of the light snow north of I-70. Expect a 3-4 hour period with light snow with scattered flurries and a few light snow showers lingering for much of the night as subtle energy aloft continues to track through the region. With liquid-snow ratios at 20-1...light accumulations are likely across the northern half of the forecast area ranging from a couple tenths to near an inch over far northeast counties.

The cold front will sweep across central Indiana during the early overnight with wind gusts immediately developing as strong cold advection commences. Periodic gusts to 30 to 35mph are possible during the predawn hours into the first half of Monday before falling back slowly late day. Despite high pressure building in Monday...stratus will be slow to give way from the southwest with an increasing likelihood that it remains mostly cloudy across the northeast half of the forecast area well into the afternoon with full clearing holding off until near sunset.

Temps/Wind Chills...wind chills will tumble below zero late tonight and should stay there all day Monday with the exception of far southern counties. With that in mind...have extended the Cold Weather Advisory for all but Greene/Knox/Sullivan Counties through Tuesday morning. While wind chills may briefly rise above the -10 threshold Monday afternoon...it remains close enough to justify the headline extension. Lows by Monday morning will fall into the single digits north of I-70. Nudged high temps lower for Monday with the clouds lingering. Highs will struggle to climb above 10 in the northern Wabash Valley with teens expected across the area.

LONG TERM (Monday Night through Sunday)

Issued at 310 PM EST Sun Jan 18 2026

An ongoing large upper level trough will persist over much of the CONUS and Canada through much of the forecast period while a few short waves move through it. At the surface, high pressure will start off the period, allowing for dry but still chilly weather to start. The expected below zero wind chills Monday night into Tuesday morning has prompted a continuation of the cold weather advisory into Tuesday morning.

Temperatures warm back up Wednesday, as well as increased winds, ahead of a surface low quickly passing just to the north of central Indiana. Ahead of the associated front, there is a chance of precipitation throughout the day, with a combo of rain and snow possible as well as elevated wind gusts. Highs should be in the mid 30s to mid 40s range Wednesday, but behind the low temps will drop back down.

This weekend will see temperatures drop further with highs Sunday potentially in the teens. Models are also showing additional chances for precipitation (namely snow) through the weekend, but there remains uncertainty that far out. Previously ice mixing in seemed possible, but latest runs show a more southern track of a low and thus colder temps and diminishing ice potential. Still will monitor trends in the thermal profile as next weekend approaches. Looking into next week, the signal is there that the end of January will be a cold one and central Indiana may struggle to see more than a few days above freezing.

AVIATION (06Z TAF Issuance)

Issued at 1158 PM EST Sun Jan 18 2026

Impacts:

- Snow showers ending, but MVFR Cigs through late morning. - Wind gusts to 30kts possible through 18Z. - VFR returns after 18Z.

Discussion:

Cyclonic flow across the TAF sites will continue overnight and into Monday morning as low pressure remains across the Great Lakes. GOES19 shows the next wave of clouds over IL and WI, with MVFR cigs that will pass across the TAF sites through the overnight and into the morning hours. Radar shows the limited snow showers across the area quickly exiting to the east. Snow showers are expected to diminish overnight as a secondary cold front pushes across the area and allows wind to become more westerly and somewhat gusty.

On Monday afternoon, high pressure over the plains will continue to build across Indiana and the lower level flow will become more anticyclonic. Forecast soundings respond by showing dry air within the lower levels with some upper level saturation arriving late in the day, indicative of high clouds. Thus a return to VFR is expected.

IND WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory from 4 AM Monday to 9 AM EST Tuesday for INZ021-028>031-035>049-051>057.

Cold Weather Advisory from 4 AM to 11 AM EST Monday for INZ060- 061-067.