textproduct: Indianapolis

KEY MESSAGES

- Moderating pattern through the middle of next week with unseasonably mild conditions expected Wednesday-Friday

- Near record high temperatures in the 60s possible on Christmas Day.

FORECAST UPDATE

Issued at 936 PM EST Sat Dec 20 2025

Forecast is in good shape this evening. The cold front has passed through the area, but mid and high cloud cover is helping keep temperatures from falling too quickly.

Mid clouds will continue to slowly move southeast tonight. Satellite shows more high clouds moving in from the west. Thus, kept skies partly to mostly cloudy through much of the night. Clouds will diminish from the north late tonight and toward sunrise.

Adjusted hourly forecasts to match latest trends in observations and satellite imagery. Low temperatures look reasonable so no changes were made at this time.

SHORT TERM (This evening through Sunday)

Issued at 207 PM EST Sat Dec 20 2025

Overall pattern through the short term will be transient with a shift from the northwest flow, that brought the recent cold air and snow, with high pressure progged to slide in overnight into Sunday. Then the longwave pattern will see the large ridge across the pacific northwest relax, which will allow the robust southwest flow to arrive and usher in much warmer air just in time for Christmas.

Tonight... frontal boundary will be sweeping in from the northwest and with high based clouds overhead and then some clearing on the lee-side of the surface ridge. Winds will shift to the northwest this evening and allow more cold air advection to flow into Central Indiana and drop temperatures tonight into the upper teens to lower 20s.

Sunday/Sunday Night... Surface ridge will dominant the day with light northerly flow, but with the upper level pattern still progressive and transitioning, the surface ridge will push east by the evening hours. This will allow surface winds to turn southwesterly by late Sunday night. Temps will generally be in the 30s for much of the day, but then the warmth kick-in for Monday.

LONG TERM (Sunday night through Saturday)

Issued at 207 PM EST Sat Dec 20 2025

Monday through Saturday... Upper level ridge axis will have shifted to the east of the Ohio Valley, as the region enters into a persistent isentropic ascent for parcels, essentially allowing for a warmer air push lifting into the Ohio Valley for the upcoming week. By Mon afternoon 850mb flow will have been solid from the southwest, helping to kick-off the robust warm-air advection and steady moisture transport with thickening clouds and some patchy drizzle or sprinkles. Tuesday the llvl jet upstream in the plains will be allowing continued northward push of moisture into the region, which will inhibit any potential for nocturnal cooling and overnight lows likely well into the 30s to perhaps even 40 degrees in the southern portions of the forecast area.

Christmas Eve... If anyone had desired a White Christmas, well, this isn't going to the the year for that. Deep longwave trough will be digging into the Western US, which means a strong and robust southerly flow for Ohio Valley. Ensembles have been in solid agreement with this holiday setup, and isn't just a one cycle or a couple, this has been consistent for almost a week now that the abnormally warm setup is going to coincide with Christmas. Current indications are that 850mb thermal ridge overhead for Christmas eve will be progged at 2 to 3 standard deviations above climo. Which may flirt with record warm temperatures if not Christmas Eve, possibly Christmas Day.

Christmas Day through Friday... Similar setup for Christmas Day, as the teeth of the thermal ridge will be overhead. Current indications are that highs for the day will be in the low to perhaps mid 60s, and overnight lows possibly not dipping below the mid 50s. Again this goes along with the robust 850mb southerly flow. Turning towards Friday and Saturday the ensembles do being to diverge, with some solutions indicating the ridging may begin to breakdown as a potential flattening to the longwave flow into a faster zonal setup.

AVIATION (06Z TAF Issuance)

Issued at 1224 AM EST Sun Dec 21 2025

Impacts:

- Winds becoming W/NW, gusts to 20kt possible before 09z

- Near LLWS conditions early in the TAF period.

Discussion:

VFR conditions expected through the TAF period.

A cold front is passing through central Indiana and winds are becoming northwesterly. IND recorded a 21kt wind gust, a few more of which may be possible before winds begin diminishing around 09z. Winds should go light and variable for a time as surface high pressure moves overhead this afternoon and evening. A switch to southeasterly is then expected after 00z as the high pulls away.

Winds aloft may be fast enough for a brief period LLWS of 30-35kt, mainly from the start of the TAF period to about 09z.

Mid to high-level clouds may pass through at times, ranging from FEW to SCT.

IND WATCHES/WARNINGS/ADVISORIES

None.