MORNING HEADLINES
– Chills in the single digits or below zero night AND day through Wednesday.
– Half-inch to one-inch of snowfall Tuesday during the daytime hours.
– Rain Friday night and Saturday morning, mixing with and changing to snow by afternoon as temps fall.
TODAY’S MAP
NWS TECHNICAL DISCUSSION
- Quick moving cold front/upper wave may produce light snow around a half inch or so Tuesday with isolated amounts near 1 inch. - Temperatures as low as -5 with wind chills as low as -15 Tuesday night. Multiple nights of single digit or lower lows expected this week - Another potential winter system next weekend with uncertainties on precipitation type, followed by another potential Arctic blast && .SHORT TERM (Today and Tonight)... Issued at 246 AM EST Mon Jan 13 2025 The cold front has now cleared all but the far southeast part of the forecast area early this morning and will do so over the next hour or so through 09Z. Much colder air has spilled into the region in the wake of the frontal passage with temps quickly falling back into the lower and mid 20s. The main challenge for today will be how much cloud cover redevelops over the region within the cold advection regime in the postfrontal airmass. The presence of broad high pressure over the Plains will gradually spread east into the Tennessee Valley by this evening and enable scattering of the clouds. Focus though will quickly turn to an approaching secondary frontal boundary diving out of the upper Midwest and likely to be on our doorstep by daybreak Tuesday. This feature will bring a quick shot of light snow with it on Tuesday and a reinforcing shot of bitterly cold air for midweek. More on that in the Long Term section below. Stratus has largely settled along and ahead of the cold front this morning and is primarily focused across the southeast half of the forecast area. There remains some stratus back across north central Indiana within the cold advection but that has been progressive over the last several hours with the expectation that much of the forecast area will clear prior to daybreak as drier air settles in. The question though becomes how expansive any stratocu will become later this morning into the afternoon. RH progs through 925mb continue to highlight deeper moisture filling back into the northeast half of the forecast area with model soundings showing a strengthening shallow inversion under the progressively drier air advecting in above the boundary layer. At the very least this should enable broken stratocu to redevelop back to the southwest across much of the forecast area with the exception of the lower Wabash Valley for this afternoon before slowly shifting east into this evening. Westerly winds will sporadically gust to around 20mph through the afternoon...especially north of I-70. Any scattering of the stratocu this evening will be relatively brief as mid level clouds ahead of the approaching secondary front quickly expanding to the region during the predawn hours Tuesday. As mentioned...a period of light snow will accompany the front but should not move into the northern Wabash Valley until after daybreak Tuesday. Winds will decrease this evening and back to southwest overnight as the boundary approaches from the northwest. Temps...the brief reprieve enjoyed Sunday from the extended stretch of subfreezing temps is gone with a return to much colder weather beginning today and persisting through much of the week. Low level thermals support highs only in the upper teens to mid 20s from north to south...and if stratocu ends up being more expansive than currently thought highs will likely be closer to the lower end of this range. Lows tonight will fall into the single digits with subzero wind chills developing towards daybreak Tuesday. && .LONG TERM (Tuesday through Sunday)... Issued at 246 AM EST Mon Jan 13 2025 Continue to expect a quick hitting clipper system on Tuesday to bring a light accumulating snowfall to central Indiana. Latest deterministic runs do not look quite as favorable as in recent days but not ready to jump on this entirely, as ensemble probabilities still support a high probability of measurable liquid precipitation, which, in a cold, high SLR environment, will easily translate to at least a few tenths to around a half inch of accumulation, with locally higher amounts. Rapidly clearing skies Tuesday night, along with a thin addition to the remaining snowpack, and a continued flow of cold air into the region, supports trending lows toward the lower end of the guidance envelope, with widespread lows near zero to a few degrees below zero, which will produce wind chills of -10 or lower with any wind. Dry but continued well below normal temperatures will persist through at least Wednesday night, when focus begins to shift toward a late week/weekend system which represents our next opportunity for precipitation. While confidence is fairly good in precipitation late in the week and into the first part of the weekend, confidence in type is extremely low, as the ensemble spread on on the position of these lows and the attendant timing of arrival for the next Arctic push, both between and within the individual ensembles, is enormous. Thus, it is important to not seize on any one deterministic run at this point. This late week system may bring temperatures back to near or even briefly above normal for a few days, but toward the end of the weekend and into the week two, confidence is broadly high that another Arctic intrusion will bring temperatures back to below normal, and potentially well below normal, during the week two period.
INDY SEVEN DAY FORECAST
Today: Partly sunny, with single digit chills. High 21.
Tonight: Partly cloudy. Chills around zero. Low 8.
Tuesday: Light snow, mainly in the late morning and early afternoon. Around an inch accumulation. High 20.
Tuesday Night: Clearing and even colder. Chills below zero. Low 0.
Wednesday: Mostly sunny. High 18.
Wednesday Night: Partly cloudy. Low 11.
Thursday: Partly sunny. High 33.
Thursday Night: Partly cloudy. Low 24.
Friday: Partly sunny. High 39.
Friday Night: Rain showers. Low 34.
Saturday: Morning rain, then snow as temps fall to around freezing. High 39.
Saturday Night: Mostly cloudy. Low 15.
Sunday: Mostly cloudy. High 26.

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