textproduct: Indianapolis

KEY MESSAGES

- Cold Weather Advisory in effect through 10 AM Monday across all of central IN for potentially dangerous wind chills, particularly tonight into Monday morning.

- Freezing Drizzle possible late Tuesday night/early Wednesday.

- Widespread rain likely late Wednesday night into Thursday with some minor flooding possible.

- Flash freeze of rain on area roads possible Thursday night.

- Above normal temps and more chances of rain next weekend.

FORECAST UPDATE

Issued at 914 PM EST Sun Dec 14 2025

Bitterly cold conditions continue across the area this evening as strong high pressure moves over the region. 02Z temperatures were already below zero in many locations with just a few spots a couple degrees above zero.

The expectation was that temperatures would drop rapidly with sunset under mainly clear skies and light winds and that is exactly what has happened. Temperatures are likely to bottom out by 07 to 08Z before winds begin to pick up as the center of the surface high passes. Over the next few hours though with just thin cirrus drifting through the forecast area...anticipate a wide variation of temperatures influenced by the snowpack. Most of the forecast area will fall into the -5 to 0 range prior to the predawn hours but localized spots will make it to -10 if not lower briefly. KHUF for instance at 02Z was at -9.

The cold advisory continues overnight with wind chills already at criteria over most of the region and remaining so through the night. Expect wind chills between -20 and -10F. Stay warm.

Zone and grid updates out.

SHORT TERM (This evening through Monday)

Issued at 314 PM EST Sun Dec 14 2025

Dry weather conditions are expected in the short term period as an arctic high moves through the region. Current surface analysis depicts the strong arctic high centered over the northern MO. Despite cold air advection the first half of today and a health snowpack, temperatures have gradually warmed up into the single digits thanks to plentiful sunshine. Slight additional warming is possible over the next few hours, but a slight northwest breeze will keep wind chills near or below zero. A Cold Weather Advisory remains in effect through 10AM Monday for the potential of dangerous wind chills, especially tonight into Monday morning.

Expect the arctic high to move overhead this evening into tonight. Winds are expected to weaken once the pressure gradient relaxes. Wind speeds will increase slightly late tonight as high pressure begins to shift east. Light winds combined with clear skies and a healthy December snowpack should allow for temperatures to quickly drop. Look for lows to range from the lower single digits across the far south to sub-zero lower single digits further north. These very cold temperatures combined with winds increasing slightly late overnight could result in wind chills as low as -10F to -19F, especially for northwest portions of central Indiana.

Guidance shows an embedded shortwave within broad troughing moving across the Great Lakes Region on Monday. While no precipitation is expected over the forecast area from this system, increasing southwesterly flow from a tightening MSLP gradient will help to warm temperatures. Look for highs in the 20s. Shallow diurnal mixing into a strengthening LLJ aloft should also promote breezy conditions. Wind gusts around 25-35 mph are possible with the strongest wind gusts likely focused more over north-central IN. These winds will make it feel like temperatures are in the single digits or teens during the afternoon.

LONG TERM (Monday night through Sunday)

Issued at 314 PM EST Sun Dec 14 2025

The long awaited pattern change commences Monday night as surface high pressure that brought Indiana's coldest temperatures in almost a year moves towards the East Coast. On the back side of this surface high southwesterly winds will usher in "warmer" air with overnight lows only in the 15-20 deg F range. Meanwhile, the upper ridge that has been a fixture off the CA coast for the last 3 weeks will gradually build eastward from the Rockies into the Midwest. As a result, temperatures will continue to climb about 15-20 degrees between Monday and Tuesday, with highs near or slightly above normal in the upper 30s to mid 40s. The major limiting factor for greater warmth Tuesday will be the presence of a broad snowpack. However, the LWC of the snow is less than normal for December thanks to the arctic nature of high SLW ratios during Saturdays snow event.

The forecast gets more complicated as we go into Tuesday Night. With the persistent deep southwesterly low level flow, ow level moisture will begin to be brought northeast into the region from the Gulf. Any warmer/moist air over a receding snowpack is a recipe for Dense Fog, and as such the expectation is for at least patchy conditions to develop Tuesday night into Wednesday. In addition a glancing blow of a strong shortwave trough moving north of the Great Lakes and a weaker shortwave trough moving across the MS valley may be sufficient to generate light drizzle and/or freezing drizzle (as both Euro and NAM model soundings indicate near 32F for northern portions of the FA).

Wednesday's high temperatures may end up lower than Tuesday's with low clouds and/or fog likely to continue for much of the day. Any drizzle/freezing drizzle is expected to be short lived given the transitory nature of the shortwave forcing.

A much more pronounced/larger shortwave will move out of the Rockies into the Plains Wednesday and into the Ohio Valley/Great Lakes region on Thursday. Strong height falls, ample low level moisture and a strong cold front spell widespread precipitation Thursday across the area. NBM pops from 70-90 look very reasonable. Questions remain on the degree of cooling and any anafrontal forcing that would support a mix of rain/snow before precip ends Thursday night. The biggest concern with this system will be both hydrologic and transportation. The hydrologic concerns are focused on the intensity and amounts of rainfall /pwats near the 90th percentile for Mid- December/, cold ground aiding in runoff and potential for some ice jams. The transportation concerns are focused on the rainfall washing off salt on area roads, ponding of water and the possible flash freeze potential Thursday night with lows fall into the low-mid 20s.

Beyond Thursday another warmup commences going into next weekend with highs expected to approach 5-10 degrees above normal Saturday. Deterministic models are in good agreement with another shortwave increasing rain chances across the region Saturday night into Sunday.

AVIATION (06Z TAF Issuance)

Issued at 1214 AM EST Mon Dec 15 2025

Impacts:

- VFR Conditions this TAF period.

Discussion:

VFR conditions will continue through this TAF period as as strong high pressure passes over the Ohio Valley. Light and variable winds are expected overnight with some high, scattered cirrus passing within the flow aloft.

Forecast soundings through the period continue to reveal a dry column, with slow warm air advection in play.

Thin mid and high clouds will pass through the area at times as the flow aloft becomes more zonal. Winds will become more southerly as the surface high drifts east.

IND WATCHES/WARNINGS/ADVISORIES

Cold Weather Advisory until 10 AM EST this morning for INZ021- 028>031-035>049-051>057-060>065-067>072.