Multiple chances for wintry weather this weekend

A period long discussed as a potential “window” for wintry weather is now within the short to medium range, and forecast models continue to hone in on the development of wintry weather for parts of the Eastern Untied States, particularly the Northeast US as early as Friday and Saturday. A large ridge in the Pacific Ocean will dislodge cold air into Canada and the Northern 1/3 of the US, while an active jet stream pattern continues.

The first disturbance approaches the area during the middle part of this week, with an additional disturbance from the polar jet driving southwards through Central Canada and potentially phasing with a trough over the Ohio Valley. This phase could allow a storm system to form quickly off the Mid Atlantic coast, with precipitation spreading northwards into the Northeast US.

As you may expect, forecast models have struggled with the differences and details of these disturbances and their interaction. The shortwave can be seen clearly and easily on the GFS model, but it arrives too late to phase and allow a storm system to form near the East Coast. The European model is closer — and its ensembles have several members producing notable snowfall in the Mid Atlantic and Northeast.

The evolution will have to be closely monitored over the next few days, as a phase and interaction between the shortwave over the Ohio Valley and the incoming polar shortwave could lead to a snowfall. Exactly how the two features behave will be critical in determining when, where, and how much snow will fall. The European ensembles currently favor a 50-60% chance of 1″ of snow throughout Eastern PA, NJ, NYC and Southern New England — with about a 20-30% chance of 3″ of snowfall.

The next storm system may arrive during the later part of the weekend, as a disturbance moves through the Central Plains and towards the Southeast US. The GFS is the most amplified with this disturbance, while the European model is flatter and less amplified/impactful. Much of the evolution of that disturbance depends on its interaction in the Pacific Northwest (far away, we know!).

We detailed that potential in our latest video. More information will be coming in the next several hours and on Tuesday, so stay tuned for the latest!