textproduct: Indianapolis

KEY MESSAGES

- Above normal temperatures continue through the weekend with near record highs Sunday

- Strong front with wind gusts possibly over 50 mph Sunday night into Monday morning along with a few thunderstorms

- Rapidly falling temperatures into the 20s on Monday with wind chill values near zero at times

- Much colder weather through next week with highs at or below freezing

SHORT TERM (Today and Tonight)

Issued at 314 AM EST Sat Dec 27 2025

Stratus remains stagnant over the region early this morning with just a small pocket of clearing across the lower Wabash Valley. 07Z temperatures were in the 40s with light and variable winds.

Upper level ridging will amplify across the eastern half of the country through tonight as surface high pressure passes to the north. An upper level low will strengthen as it drops into the northern Plains tonight before eventually influencing a surface wave tracking through the central Plains as it lifts E/NE into Sunday. This will lead to bigger impacts locally for the second half of the weekend but the return of a warm front northward into the region late tonight will provide the initial threat for showers predawn Sunday.

Expect any clearing over southwest portions of the forecast area to fill back in over the next few hours as the shallow inversion remains strong. Ceilings are likely to lower through daybreak and as the axis of the ridge aloft shifts into the area will need to monitor for potential expansion of fog into the northwest half of central Indiana. Do not anticipate fog coverage to not be anywhere near as widespread as what occurred Friday morning...but the lack of substantial wind flow through the boundary layer and the lowering of the inversion into the near surface layer could present a period with locally thicker fog for a few hours either side of daybreak.

The surface high will shift into the eastern Great Lakes by midday with return flow commencing for this afternoon and evening. Sounding analysis shows the inversion remaining stout into the afternoon but the deepening of the dry air and subsidence above 900mb will be able to slowly weaken the inversion to the point where the stratus should lift and mix out enough to where there will be breaks in the deck for the mid and late afternoon. This will be temporary as warm advection in advance of the warm front lifting into the lower Ohio Valley this evening will allow for the inversion to once again strengthen and thicker stratus to envelop the region into the overnight. The combination of a subtle increase in isentropic lift and the warm advection as the boundary lifts north across the forecast area tonight will aid in the development of scattered showers overnight which will largely focus across the northern half of the forecast area into Sunday morning.

Temps...lowered highs today in most areas from the blend by a few degrees considering the impacts from the stratus deck for most of the day. Low level thermals suggest a wide range from northeast to southwest from the upper 40s to around 60. Lows tonight will occur during the evening at readings no more than 5 degrees below the highs. Then as the warm front lifts north overnight...expect a steady rise of several degrees by daybreak Sunday.

LONG TERM (Sunday through Friday)

Issued at 314 AM EST Sat Dec 27 2025

The roller coaster ride of weather continues for the last week of the year going from record highs and thunderstorms to high winds and snow within a 24 hour period. Wintry weather returns for the new year with another extended stretch of below freezing temperatures and occasional chances for snow.

The main focus with this morning's discussion will be the Sunday through Monday timeframe as a strong front brings multiple weather hazards to Central Indiana.

The period begins with a deepening sub 515dm upper low traversing the Central Great Lakes within the left exit region of 140+KT jet. Central Indiana will be firmly within the warm sector of this developing mid latitude low as the warm frontal feature pushes well to the north along the MI/IN border aided by a 45-55 kt low level jet pumping in ample moisture and warm air northward.

Sunday morning begins with low clouds and potentially fog and drizzle as the region remains entrenched under a strong low level inversion with a near saturated layer at the surface. Forecast soundings do show strong low level warm air advection working to quickly warm the boundary layer through the day with the low level inversion slowly rising and deepening the near surface mixed layer. Isentropic lift within the vicinity of the warm front will keep drizzle and scattered showers around, especially north of I-70 for at least the first half of the day. Southerly winds increase through the day in conjunction with a tightening pressure gradient and deeper mixing into the strengthening low level jet. While clouds are not expected to break due to the strong inversion and ample moisture below it, warm air advection and mixing should be strong enough to push temperatures to near record territory for much of the region. Highest confidence in highs in the upper 60s to possibly 70 degrees will be along the I-70 corridor and points south where there should be a break from any drizzle or light rain during the afternoon. Will have to watch how far north the warm front lifts, as that is where dreary conditions may persist longer. If this front is slower to lift north, portions of North Central Indiana may remains relatively cooler than areas further south. For now have a temperature gradient ranging from near 64 at Kokomo to 71 in South Central Indiana. Temperatures will follow a non-diurnal curve Sunday, remaining elevated into the nighttime hours before the front passes through.

The impactful conditions arrive Sunday night into Monday morning with the passing of the strong front. Moisture instability will be present, as a strengthening 50-60kt LLJ advects a plume of moisture with PWAT values nearing 1.25 inches, which is abnormal for this time of year. There does appear to be a convective risk along the front Sunday night, as dewpoints climb to near the upper 50s to perhaps even 60 in some spots and guidance continues to depict upwards of 500 J/kg of MUCAPE along the front. Despite guidance hinting at low surface based CAPE values, the presence of strong low- level shear all suggests that some low-topped convection could efficiently transport higher energy to the surface and result in some thunderstorm activity. Best threat for convective activity will be in the western 2/3rd of the region, before instability dissipates later in the night. Outside of any convective activity, strong winds with gusts of 40-50+ are expected just ahead and behind the front. Any convective activity tapping into mid and upper level instability may have the potential to produce isolated gusts 50-60+ mph at times. This will be something to monitor closely through the nighttime hours. With confidence increasing in an extended period of windy conditions along with the threat for strong storms, a Special Weather Statement has been issued for this timeframe. Additional headlines may be needed in later forecast issuances.

Monday will be a return to winter, in an abrupt way. 850mb thermal trough makes a quick return and will cause temps to crash quickly, which could introduce a concern for rapid freezing; however, most guidance indicates that frontal passage will also have a narrow dry slug quickly approach and this should be enough to cause subsidence at the surface, drying the environment out quickly before any freezing issues develop. Expect temperatures to plummet from the 60s into the 20s within just a few hours of FROPA across Central Indiana. Strong winds will make for wind chill values near zero degrees Monday morning, remaining in the single digits and teens through the day. Gusts near 50 mph in the morning slowly diminish into the 30-45mph range during the day and remain elevated into Tuesday.

Lingering flurries and snow showers persist through the day on Monday within a cyclonic flow pattern as the area of low pressure departs to the northeast. Best chance for snow showers exists along and north of I-70 with better chances as one heads north. A dusting may be possible under a heavier snow shower; however with such windy conditions, it will be hard for snow to stick to the ground.

The arctic airmass keeps the cold air back into the Ohio Valley through the week with highs struggling to get above freezing. A northwesterly flow pattern sets up during the week with Indiana potentially being in the path of a few clippers dropping southeast from Canada. While high pressure keeps the area mainly dry for the first few days of next week, there are hints that flurries and light snow chances may be around Wednesday into Thursday. Confidence is low on details at the moment as these clippers have not developed yet. However this pattern setting up does support a few light snow chances in the area. Will monitor the mid to late week timeframe for light snow and update the forecast accordingly as confidence increases. Despite lower confidence in finer details, high confidence remains that much colder temperatures persist into early January.

AVIATION (12Z TAF Issuance)

Issued at 605 AM EST Sat Dec 27 2025

Impacts:

- IFR ceilings this morning, gradually lifting to MVFR this afternoon - a brief period with VFR ceilings possible mid afternoon through early evening - IFR ceilings return tonight with scattered showers developing

Discussion:

IFR stratus remains across central Indiana early this morning and will continue at the terminals into the early afternoon. Brief visibility restrictions are possible over the next few hours in localized fog. Stratus will be stubborn to mix out with the shallow inversion persisting but it appears enough dry air will filter down into the near surface layer by mid afternoon to at least partially mix out the lower stratus with a brief opportunity for VFR conditions late day into early evening. Southeast winds generally less than 10kts are expected today.

IFR level stratus will return tonight in advance of the low pressure and frontal boundary that will bring rain to the region on Sunday. Isolated to scattered showers are possible late tonight but the bulk of the rain will hold off until during the day Sunday. Winds will veer to S/SE tonight and increase.

IND WATCHES/WARNINGS/ADVISORIES

None.