textproduct: Indianapolis

KEY MESSAGES

- Wind gusts around 25 to 35 mph will persist through late afternoon then diminish tonight

- Wind chill values around zero to a few degrees below through tonight

- Return to seasonable winter temperatures the rest of the week with chances for flurries and light snow Tuesday and Wednesday evenings

SHORT TERM (This evening through Tuesday)

Issued at 248 PM EST Mon Dec 29 2025

Expansive stratus deck persist across Ohio Valley this afternoon, with the return to winter conditions at the surface. Strong cold air advection still in place across Indiana, with a tight isallobaric gradient beginning to relax marginally and allow the better mixed layer to decrease with only gusts on occasion still gusting to 45 mph. Expect as the late afternoon hours progress this will further decrease, which will allow the headline to expire at the current planned time of 21Z. Enough lift is still present coupled with moisture that is allowing the vertical parcel momentum to still generate some light snow showers and flurries, although it has been trending to be more flurry dominant than anything else. Temperatures have settled into the mid/upr teens, and the thick cloud cover should inhibit temps from plummeting much lower overnight.

Tonight...Upper level 500mb trough axis pivots east across the region tonight, with a surface ridge sliding south/southeast through the TN valley. This will reinforce the northwest flow within the boundary layer for Indiana. No additional moisture is present, so expect flurries to generally become more sporadic or end by late this evening if not sooner.

Tuesday through Tuesday Night...With the deep trough still After record warmth on Sunday and a line of convection that produced wind damage across parts of the region...winter has returned with a vengeance early this morning. Westerly winds have been consistently gusting at 45 to 50mph over much of the forecast area since last evening. Temperatures which just a scant 6-8 hours ago were in the mid and upper 60s now range from the mid 20s to lower 30s at 07Z.

Low pressure is in the process of reaching its peak intensity near 980mb over Lake Huron early this morning. The Ohio Valley is now firmly in the backwash of the intense low but a surface trough extending west from the low is set to pivot across the region later this morning into the afternoon before high pressure finally begins to exert its influence tonight.

The strong cold advection in the postfrontal environment was aiding in flurries and narrow bands of light snow showers over central Illinois in the vicinity of the elongated wave aloft to the southwest of the upper low. The ongoing flurries and light snow showers to the west will shift across the northeast half of the forecast area over the next several hours then continue through the morning as the upper wave swings through in tandem with the surface trough. Steepening lapse rates within the boundary layer will aid in coverage as well with snowflakes persisting into the early afternoon before diminishing from the southwest as drier air aloft advects into the region. Expecting little if any impact from the snow with no accumulation as snow remains light and winds continue to efficiently blow flakes around. Flurries may linger over northeast counties until near sunset with dry conditions going forward into tonight.

Sustained winds currently are at 20-30mph across the northern half of the forecast area with gusts routinely hitting 50mph. Further south...gusts have generally been no higher than 40mph. Plan to continue the Wind Advisory over the entire forecast area but may be able to remove southern counties by midday should gusts remain at current levels. As the surface low pulls away to the northeast this afternoon...gusts will begin to decrease with the pressure gradient relaxing.

Finally...have kept cloud coverage high through tonight as model soundings show moisture remaining trapped beneath an inversion. Drier air aloft will work down into the boundary layer by tonight but it may be the predawn hours Tuesday before lower stratus significantly diminishes from the west.

Temps...should fall into the teens and lower 20s after daybreak before subtle recovery occurs later today. Low level thermals support highs largely in the mid 20s. Lows tonight will be in the teens.locked in across the region, it appears a series of weak clippers will skirt the region starting Tue ngt. Guidance has continued to indicate the next clipper will quickly dive into the Great Lakes region midday Tue, laying out a frontal boundary in it's wake. This boundary and some added moisture will trail this feature late Tue into Wed. But for Tue prior to this feature we expect some steady erosion to the cloud deck that it should produce some clear skies for Indiana or at least more breaks. Upstream this afternoon we are already noticing this, so we have a higher degree of confidence that we will indeed be able to erode the stubborn stratus deck Tue midday. With winds relaxing Tue, and less of a potent cold air advection airmass, we should be able to rebound temps into the upr 20s.

Tue ngt... clouds will steadily thicken again from the northwest to southeast, in advance of the next clipper system. Temps ngt should stabilize in the teens to lower 20s.

LONG TERM (Tuesday night through Monday)

Issued at 248 PM EST Mon Dec 29 2025

A pattern more typical of winter will continue for much of the week as we stay in a colder northwesterly flow pattern. A few weak clipper systems moving through this northwesterly flow will impact the Great Lakes region bringing light snow chances to central and southern Indiana.

Wednesday through Thursday...

The best chances for snow will arrive on Wednesday evening as a mid level wave/clipper system moves across the area. This will be associated with a stronger upper level jet and coincide with the arrival of a cold front sending overnight lows Wednesday into Thursday back into the teens with windchills potentially down into the single digits. While the orientation of the upper level jet is more favorable for snow, we lack any appreciable surface low that would accompany the mid-level shortwave. Because winds stay out of the north we won't see any noticeable increase in moisture ahead of this clipper system. So, the QPF forecast remains on the lighter side. Did nudge QPF up a tad from what the NBM was suggesting of zero QPF over central Indiana. Most models and ensemble members have at least 0.01 QPF along and north of the I-74 corridor. Snow Ratios would be around 12-14 to 1, so any QPF that is present should be able to squeeze out to a Trace to upwards of a half an inch in some locations in north-central Indiana. Thursday remains on the cooler side with temps in the low to mid 20s but should see some clearing skies.

Friday into the weekend...

The pattern of a ridge in the west and trough in the east that kept us on the cooler side this week begins to break down as we head into the weekend. Higher pressure gradually builds into the S/SE US allowing for winds to shift to the south to southwest. Temperatures begin to warm back to near to slightly above normal over the weekend with highs approach 40 degrees by Sunday and Monday. Confidence in the forecast beyond the weekend is low as overall flow pattern across the CONUS becomes messy and could potentially see the redevelopment of a ridge in the west and trough in the east. Either way we are probably back to the near to slightly below normal temps next week.

AVIATION (00Z TAF Issuance)

Issued at 619 PM EST Mon Dec 29 2025

Impacts:

- Widespread MVFR ceilings persisting through the night

- Occasional flurries or light snow showers through the evening

- Wind gusts as high as the low to mid 20KT range through the evening, with additional gustiness approaching 20KT on Tuesday

Discussion:

A widespread MVFR low stratus deck remains trapped across the area tonight, and will persist through much of the night and into Tuesday morning before lifting to VFR.

Though mixing is dropping off and the pressure gradient has begun to relax, occasional gusting is expected to continue into the evening hours before ending along with the lingering flurries/snow showers late tonight. Gusts should be no higher than the low to mid 20KT range, and will be sporadic.

Gusts will return Tuesday, but will be more in the upper teens to around 20KT range. Winds will be from 290-300 degrees overnight, slightly backing to 260-270 on Tuesday.

IND WATCHES/WARNINGS/ADVISORIES

None.