With all the chatter out there about a storm this weekend, I wanted to give a quick fact based, no-nonsense rundown and analysis of the potential snow event. There certainly is potential for some flakes to fly but several notable inhibitors will likely prevent a major storm. I also wanted to highlight the pattern for the coming week or so which will feature “tundra weather” aka cold and dry.
Our first chance for flakes will be Friday morning as a storm zooms by offshore. Only the coast will be at risk for some flurries which won’t amount to more than a dusting. Any steadier snow will be limited to SE MA, RI, SE CT, and E LI. The mountains of our area will remain dry. The best shot for some coastal flakes will be from 6-11 AM Friday morning with snow lasting a little longer in the aforementioned areas of SNE.
This storm will be weak and remain well to our SE because of the orientation of the 500mb trough. Notice that the trough is shallow, weak, and positively tilted (from NE to SW). This means that the dominant steering winds are from the WSW which will understandably keep the storm moving ENE. Also notice the two disturbances highlighted back to the west. These are the building blocks of any potential weekend storm and their interactions will determine whether the coast will see a plowable snowfall or if we remain locked in the cold, dry pattern that arrives after tonight’s cold front.
There is continued disagreement among model guidance regarding the interaction of the two disturbances. The GFS shown to the left keeps both systems separate and positively tilted. This means that the situation would be setup similarly to the event Friday morning with limited impacts. The Euro digs the steering disturbance (the one farther NW over the Great Lakes) deeper and phases both disturbances into one system that turns negatively tilted. This would result in a more significant storm capable of bringing plowable snow to the coast.
Looking at the jet stream, the setup in the upper levels continues to point towards a weaker system that slides farther east. Notice the low amplitude (flat) flow with only a very shallow ridge over the west coast and trough over Hudson Bay. Our storm will be developing in a favorable right entrance region but it will be embedded in extremely fast flow moving across the country. It also won’t have the benefit of a coupled jet streak setup where the left exit region of one jet overlaps with the right entrance of another.
Taking a quick look at the next 7 days, you can see how the term “tundra weather” would be apt. Temps will fall below freezing tonight and likely won’t rise back up to that mark until a week from today at the earliest. This graph is for Portland so expect that temps inland will be even colder and in the mountains, the next thaw might not be for several weeks as Arctic high pressure systems are only briefly punctuated by warmer clipper systems.
Our next chance for snow looks like a clipper sometime on Monday or Tuesday. After that, any details are lost to the mists of time but signals are showing up for an inland runner type system in roughly a week’s time. In the meantime, bundle up and throw some sand on that driveway because any ice tomorrow morning isn’t likely to melt off in a hurry!