After a relatively quiet end to January, we are starting February with more cold and our next window for measurable snow opening. Because a lot is happening, I need to fold in the first call forecast for tomorrow's clipper in with the forecast for the week ahead. A packed agenda!
Sunday-Monday
January turned out to be a month of normal cold, but that didn't translate into normal snowfall or precipitation. The windows that we had either flopped or underwhelmed. Tomorrow brings our next chance of snow, and it comes from a clipper system that has quietly looked more respectable on guidance in the last day or so.
We have another press of cold that made it into the state today, and that cold will remain in place tomorrow, especially inland. This will set the stage for snow as a weak clipper passes the region to the north. Now, because it's passing to the north there is going to be some flow seeking to erode the cold in place, but the timing of all of this supports widespread snow, even to the coast. For the shoreline, the question becomes how much cold is able to stay locked in during this event.
Below is the latest high resolution NAM for our system. Here, you see snow showers possible by late tomorrow afternoon, but the heaviest snow is later at night into the early Monday hours. There's very little erosion of cold here, which means more snow at the coast.
Across guidance this is a fast mover. I expect snow to begin from west to east, with possible mixing at the shore, between 6-10pm. The worst of the system happens later in the nighttime hours, probably between 10pm and 1am, with the snow done long before sunrise.
Snow Accumulation
Let's drill a little deeper into the snow accumulation forecast, which gets weighted 2x in the grading. First, like I said above, I'm less than enthusiastic about a C-2" zone. We know from our plow operators that a range like that is a pain to deal with. What I would say is that the greatest chance of a coating (something measurable but less than an inch) is right along the immediate coast, and a little further inland in SE CT. Because of the temperature gradient that's possible, I would expect a snowfall gradient as well in this zone. So as an example, in a place like coastal Guilford you could see a coating of snow, while just a few miles inland there's an inch on the ground and a few miles further inland there's two inches or just above. If it stays cold enough, this should be a good ratio snow, so the gap between the floor and ceiling may be higher. For this C-2" zone I'll consider readjustments tomorrow.
For inland areas, this is pretty straightforward. It'll be cold enough. We'll get a good ratio powdery snow. We just need the lift that's depicted on the guidance to come to fruition, and I increasingly believe it does. I contemplated a 2-4" zone, but I think a broad 1-3" with some isolated 4" spots possible in our NW and NE hill towns works for now.
Impact
This looks low impact to me. There's no real power outage or wind thread, hence no formal forecast for it. This is happening later on Sunday, mostly after dark, with the worst during the late night hours and the system done before sunrise. The track of the system will also eventually introduce mild air into the region, and Monday looks warm. If you wait to measure your snow until later in the day on Monday it'll be inaccurate because of melting. There may be some delays on Monday, but I think the timing and warmth on Monday keep those to a minimum. We'll see.
Tuesday is another mild and quiet day, with sunny conditions and temperatures in the low 40s. We'll be watching another press of cold as our pattern shifts to very fast and very active.
Wednesday-Thursday
The middle of the week is looking like a microcosm of the pattern ahead: an absolute mess. This is the kind of pattern that is all over the place, filled with uncertainty, and prone to cause forecaster headaches. We go from thinking about coastal storms, to watching a "gradient" pattern. This is the kind of pattern where we look to see how far south cold presses in advance of a strung out system. Don't let that characterization fool you, however, these "overrunning" strung out systems can pack a punch in providing plenty of precipitation.
Wednesday and Thursday provide the opportunity for just that, as cold presses in and a battle between warmth (enough for rain) and cold ensues. The middle of the week event for now looks modest, but any time we're looking at potential ice, it won't take much to cause widespread issues.
The GFS, which has some work to do to reestablish my confidence in it, keeps Wednesday dry and brings a snow to mix/ice mess on Thursday.
With seesawing boundaries, the track of these systems will matter a lot. Friday will be warmer or colder depending on what happens Thursday. The weekend does look to cool off in advance of the next system. This one has a more significant signal, particularly for Super Bowl Sunday, but this far out it's hard to know which side of that gradient we end up on.
One thing is clear, however. There is a cross guidance signal that things get active, with storm chances every 2-4 days. It's going to be a busy first half of February with all precipitation types on the table. Buckle up...
Sunday: Increasing clouds with snow (some shore mixing) late. Highs in the upper 20s to low 30s inland. Low to mid 30s at the shore. Chance of snow 90%.
Monday: Snow in pre-dawn hours. Decreasing clouds and seasonably mild. Highs in the low to mid 40s.
Tuesday: Mostly sunny. Highs in the upper 30s to low 40s.
Wednesday: Mostly cloudy with a chance of snow/mix late. Highs in the low to mid 30s. Chance of precipitation late 30%.
Thursday: Snow/Mix/Rain possible. Highs in the mid 30s to low 40s. Chance of precipitation 60%.
Friday: Mostly sunny. Highs in the mid to upper 30s.
Saturday: Mostly sunny. Highs in the low to mid 30s.
Sunday: Snow/Mix/Rain possible. Highs in the low to mid 30s. Chance of precipitation 60%.
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Thank you for reading SCW.
-DB