Temperatures across the country are wildly different from two weeks ago. You could say that fall has finally made its way to our doorsteps, but it could be argued that winter is actually the one knocking. Record lows and highs are being set in Texas as temperatures struggle to get into the 50s. Cooler air is spreading across the country thanks to the latest jet pattern. Two cold fronts, today and tomorrow, will bring cold, arctic air to the region, along with the possibility of lake-effect snow on Thursday.
This morning, a cold front associated with a surface low over eastern Quebec is sweeping over the Northeast. Mostly dry air and fall-like temperatures in the 40s and 50s will follow this cold front, bringing significantly colder weather than yesterday. However, these temperatures aren’t too much of a deviation from what is considered seasonable. In ME and northern NH, this front has brought strong winds of 40 mph. This means both a possibility for property damage as well as a higher wind chill of nearly 20 negative degrees in those areas. Some parts of upstate NY, especially along the Adirondacks, could see a few light, scattered showers today. However, the next day should simply be chilly and partly cloudy for many parts of the Northeast and New England.
Tomorrow is when it really gets interesting. Another shortwave trough will be making its way into the Great Lakes region from the Midwest tonight. Low temperatures for tonight will get down into the 30s and 40s for most of the Northeast, but this is ready to change as the trough continues to move eastward. This winter-like trough will force unseasonably cold air into the region. The arctic jet will be much farther south this week, hovering just over the 40th parallel. This feature is what makes this shortwave trough more typical of something we’d see in the winter rather than the fall.
The cold front attached to this low pressure will likely swing across the region starting early tomorrow morning. Northern New England will be the first to see the major cooling effects, while the rest of the Northeast should see the passage of this front by the end of the afternoon tomorrow. Moisture will be limited for many areas with this cold, dry arctic air. However, lake-effect precipitation is certainly possible. Strong instabilities from warm lake water underneath frigid air temperatures will cause, essentially, a need to flip the lower part of the atmosphere. Wet, warm air on top of the lakes will provide enough moisture for showers to move across the Great Lakes region. As the boundary layer cools, many rain showers will switch over to snow. Accumulations will vary from light dusting to 1-3 inches possible for higher elevations. Many parts of New England and upstate NY can expect to see a few flakes.
As flow becomes more westerly by the end of the day Thursday, snow and rain will be mostly out of the region. Only cold air will be in its place. Lows for Wednesday and Thursday night are expected to be in the 20s and 30s, which will mean frost advisories across the region. By Friday, this cold spell will be over as an upper level ridge brings slightly warmer, more seasonable temperatures into the Northeast.