Illinois, Indiana, Ohio, Pennsylvania, Maryland, and New York Face Renewed Cold and Snow Risk as Jet Stream Dips South Jan 11–18
BALTIMORE, MARYLAND — A developing jet stream shift is setting up a renewed period of cold air intrusions across the Eastern and Midwestern United States from Sunday, January 11, through Saturday, January 18. Forecast guidance highlights Illinois, Indiana, Ohio, Pennsylvania, Maryland, and New York as core impact areas, with colder air returning in multiple waves and creating a favorable background pattern for potential winter weather as mid-January unfolds.
Jet Stream Configuration Allows Repeated Cold Air Pushes
Upper-level analysis shows the polar jet stream bending southward, opening the door for Arctic-origin air to spill back into the Midwest, Great Lakes, and Mid-Atlantic. The first surge arrives early in the period, with additional reinforcing shots of cold later in the week as the trough reloads.
This setup matters because repeated cold intrusions help lock in below-normal temperatures, increasing the odds that any approaching disturbance could tap into cold air already in place — a key ingredient for snow rather than rain.
Deep Trough Signals Active Winter Background Pattern
The focus of the current forecast is on 500mb height anomalies, which depict the large-scale atmospheric pattern rather than individual storms. Consistent signals point to a deep trough centered over the eastern half of the country, a classic winter configuration that supports snow, ice, and sustained cold across multiple states.
At this lead time, it is normal for one model run to show widespread snowfall while another shows little or none. Those differences reflect uncertainty in surface details, not a lack of winter potential. As timing and placement of shortwave energy become clearer, confidence in specific impacts will increase.
Cold Air Expected to Reach the Ohio Valley and Mid-Atlantic
One notable feature of this pattern is how far south the cold air is projected to extend. Forecasts indicate cold air pressing through the Ohio Valley and Mid-Atlantic, placing states like Ohio, Pennsylvania, Maryland, and Virginia on the colder side of the pattern.
For cities that often sit near the rain–snow line, this increases the chance that thermal profiles favor snow if a storm system develops. While this does not guarantee snowfall, it raises the ceiling for winter outcomes compared to earlier January setups.
Mid-January Climatology Favors Snowfall
Climatological data strongly supports heightened winter potential during this window. Historically, about 75% of seasonal snowfall occurs between January 15 and February 28 across much of the Midwest, Great Lakes, and Northeast.
The alignment of this climatological peak with a favorable jet stream pattern adds confidence that the upcoming period represents a meaningful winter window rather than a brief cold snap. Even if the first system underperforms, the broader setup suggests additional opportunities later in January.
Why Specific Storm Tracks Remain Uncertain
Forecasters are intentionally cautious about highlighting individual storms at this stage. While the upper-level pattern is well-supported, the surface reflection remains less certain, and small timing changes can significantly alter outcomes.
As the atmosphere begins to phase cold air, moisture, and lift, confidence in storm tracks, precipitation type, and impact zones will sharpen quickly — often within just a few days of an event.
What Residents Should Monitor Next
People across Illinois, Indiana, Ohio, Pennsylvania, Maryland, and New York should keep a close eye on:
- Persistence of deep troughing
- Cold air holding in place ahead of disturbances
- Shortwave energy rotating through the trough
If these elements align, the period from mid to late January could bring multiple winter weather chances, not just a single event.
As this potentially active winter pattern evolves, staying informed will be essential. For continued updates on cold air outbreaks, snow potential, and regional weather impacts, visit ChicagoMusicGuide.com for the latest forecasts and expert breakdowns.