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– Look for continued very cold temperatures, some 15 degrees below normal through Monday.
– Temperatures moderate above freezing midweek before another cool down for next weekend.
Via @NWSIndianapolis: The first week of December will sure feel like Winter across Central Indiana! The weather pattern will consist of numerous weak waves within the jet stream diving southeast out of Canada, reinforcing persistent troughing over the Great Lakes and Northeast CONUS. These waves will be relatively weak with the biggest impact being renewed shots of arctic air diving into the state. With such a cold airmass in place, it won`t take much to saturate the environment enough to result in flurries or sprinkles at times. There will be surface high pressure attempting to push into Indiana from the west beneath the NW flow and cold air advection, which will work to keep the surface relatively dry through the period. Given the set up, keeping PoPs low through the period and messaging more of flurries/sprinkles rather than organized showers or areas of precip.
The first in a series of waves dives southeast from Canada and into the Ohio Valley Monday, following a similar track to the clipper from Saturday evening. This system will largely be moisture starved; however scattered light snow showers will be possible the first half of Monday across Southwestern and South Central Indiana. The main weather impact however will be the persistent cold air advection keeping surface temperatures below normal with highs struggling to reach the 30 degree mark and lows in the teens the first few days of the week.
The pattern begins to shift slightly over the middle of the week as the next in a series of waves dives southeast and into the Great Lakes region. The track of this wave looks to be a bit further north than the previous ones with brief low level ridging setting up ahead of it Wednesday. Despite weak “warm air advection”, denser, arctic air at the surface will be slower to respond, as is usual in these types of set ups. Guidance likely is warming the surface too fast midweek, so keeping highs slightly below guidance for now in the mid 30s to near 40.
Despite a stronger system for midweek, the best forcing for ascent and moisture convergence will be north of Central Indiana, within the Great Lakes region. By the time this system taps into deeper moisture from the Gulf, the best moisture advection and the cold front will have already shifted east, keeping Indiana relatively dry. Potential is there on Wednesday for sprinkles at time, but no appreciable precipitation is expected. While this system is a few days out, BUFKIT cross sectional profiles and forecast soundings from medium range guidance do show a low level saturated layer developing with an above freezing warm nose aloft. Confidence is lower at the moment, but this pattern with southerly flow over a shallow arctic airmass a the surface, weak lift, and a low level saturated layer could result in freezing sprinkles/drizzle at times Wednesday morning. Will keep an eye on this over the next few days.





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