HEADLINES
– Rain again Tuesday, potential for 0.50-1.00 inches of rainfall north of I-70…
– Noticeably colder after mid-week with single digit wind chills possible towards the weekend as arctic air builds in…
– A chance for light snow Thursday night…
– Potential for a significant winter storm in the Midwest Sunday into Monday…
– Bitter arctic cold in the week 2 period…
NWS Indianapolis technical discussion:
...The next weather system will cross the Midwest tonight into Tuesday bringing only rain to central Indiana through Tuesday afternoon. Low pressure already beginning to eject from the Colorado High Plains, will track eastward and bring at least light showers late this evening to western counties. Main slug of rain to fall after midnight tonight (and through morning rush hour at least north of I- 70) as the surface low tracks along I-70 from near St. Louis to over the Indianapolis Metro. Periods of lighter rain/drizzle to continue over the local region during midday and afternoon hours Tuesday...as the main forcing departs to our NE while a trough lingers below ample mid-level moisture into Tuesday evening. Storm total rainfall is expected to range from around 0.25 inches across far southern zones to around a half-inch along the I-70 corridor, to 0.70-0.90 inches over the region`s northern third. This light to moderate rainfall, will combine with already near-saturated soils to maintain Action Stage levels along several Wabash River points through later portions of the forecast period...and to a lesser extent contribute to the potential for Minor Flooding on lower portions of the White River as early as Tuesday afternoon. Moderate, mainly southeasterly breezes will prevail through early Tuesday as the circulation approaches...with more robust, northwesterly gusts to 20-30 mph expected as showers taper off late Tuesday. The overall damp conditions will bring a lower diurnal spread, with lows Monday night around 40-45F and highs Tuesday (morning) near 45-50F before readings closer to 40F settle in by late day. The normal max/min at Indianapolis early this week is 37/23. .LONG TERM (Tuesday through Sunday)... Issued at 304 AM EST Mon Dec 30 2024 Overview: A complex, active and much colder weather scenario is expected to unfold across Central Indiana over the next several days. The long anticipated significant shift in the upper air pattern will develop and help usher in the arctic air and wintry precipitation potential. This cold will likely persist through at least mid to late month before another shift back to seasonably mild becomes possible. New Years Eve Night Deformation zone behind departing low pressure will move across most of central Indiana Tuesday evening. Models have bulk of precipitation exiting rather quickly as thermal profiles cool enough to support transition to all snow. Low level temperatures also look to stay above freezing until threat of precipitation ends toward midnight. Would not be surprised if a brief burst of wet snow occurs with this deformation area, especially over eastern locations, but with warm ground temps above freezing will not add any accumulations at this time but will need watch this period. New Year Day through Thursday Winter arrives to begin the New Year as much colder air sweeps into the area under northwest flow and weak high pressure. However, this initial shot of cold air will simply bring temperatures down to near normal values, but given recent mild stretch of weather it will feel quite cold for any outdoor New Year Day activities. Apparent temperatures look to be in the teens through the day. It will remain dry during this period. Thursday Night through Sunday A fast moving short wave is now forecast to cross the region Thursday night into early Friday, aided by left front quadrant of approaching upper level jet max. Models have struggled with timing of this weak wave and uncertainty remains high in regards to snow chances and amounts. What we know is moisture is limited and thermal profiles support snow. Pops right now are in the low chance category, a function of the model discrepancies in timing and QPF. This is reasonable for now until better agreement in models develop. Second round of cold moves in behind this short wave for the weekend with even colder air to follow beyond the day 7 period. Highs will only be in the 20s with lows in the teens and apparent temperatures into single digits and possibly flirting with sub zero for brief periods late in period. Models continue to depict a significant winter storm in the Sunday to Monday time frame across the Midwest and Ohio Valley. Model differences continue but the 00z global model runs of the GFS and EC have come into a little better agreement with synoptic pattern. Still a long ways out and many changes expected. Right now all pcpn types would be in play, including ice and sleet. However, as we have pointed out many times, way too much lead time and uncertainty for any specific detailed forecasts. Disregard any snow and ice forecasts at this time but remain aware and stay informed from reliable meteorologists as the week progresses and details begin to clear by late this week. Days 8 to 14 Well below normal temperatures expected with high confidence during this period. Coldest air of the winter season and we could see highs struggle to leave the single digits and lows near or below zero. If significant snowpack develops from the aforementioned winter storm, even colder temperatures would be on the table in this period. Long range models due show a piece of the polar vortex breaking off and sinking into lower Canada, aiding in the development of Hudson bay low and sustain northwesterly flow aloft driving the cold air southward. However, models do not show a classic pure meridional, cross polar flow which is often needed for the extreme, record breaking cold. However, at this time it does look like a good January arctic blast that needs to be prepared for by everyone. Now would be a good time to begin review winter storm and extreme cold checklists and getting together recommended emergency supplies in anticipation of very cold temperatures.
INDY SEVEN DAY FORECAST
Today: A mix of clouds and sun. High 48.
Tonight: Cloudy. Rain after midnight. Low 44.
Tuesday: Periods of rain in the morning. Scattered showers in the afternoon. Gusts to 30 mph. High 47.
New Years Eve: Rain and snow showers. No snow accumulation. Low 29.
New Years Day: Partly to mostly cloudy, with chills in the 20s. High 31.
Wednesday Night: Partly cloudy. Low 25.
Thursday: Partly sunny. High 36.
Thursday Night: Mostly cloudy, with snow showers possible. Little accumulation. Low 27.
Friday: Mostly sunny. High 29.
Friday Night: Mostly clear. Low 18.
Saturday: Mostly sunny. High 28.
Saturday Night: Partly cloudy. Low 20.
Sunday: Snow likely. Accumulating snow possible. High 26.






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