A wet weekend ahead
The low-level water vapor image from 3 AM shows all the players on the table. The key piece that is causing some level of uncertainty is the trough kicker that is entering British Columbia. The models have not had a good handle on it given the fact that it is in a dead zone where weather balloons can't sample it to get a read on it. That changes today. By Friday morning, there will be better data and the forecast will come into line.
Friday 8 AM to Monday 8 AM - While forecast uncertainty remains, the ideas of the phasing of the polar jet and the subtropical jet appear to be too late for a storm of significance to generate over the region. That is a different story for Atlantic Canada as they are likely to get a decent storm. With the phasing well offshore, that cuts down on the rain amounts over Maine to a certain extent. Rain begins over southwestern areas Friday afternoon which will overspread the region overnight and continue with various intensities through the day. The uncertainty comes in for Sunday. The ideas are out there of an inverted trough set up as the GFS model here depicts which could keep the rain going and may bring snow to the higher hilltops as cold air gets injected into it.
Since this setup is more disturbance oriented given the late phase and residual upper-level energy tracking along a slow-moving surface boundary, there is a certain amount of bust potential that comes into play. There could be an issue with dry slots in between which may decrease rain amounts. Pending on how the lead low decays and transfers energy to the disturbances generated in its wake could cause overperformance, and the inverted trough may enhance that.
The jury is still out in my mind on how much rainfall will come out of this for the reasons mentioned. The over / under of roughly 1" is a reasonable expectation. Individual ensemble ideas are still running around a 50/50 split between more and less.
The ideas on wind appear manageable. I am not so concerned about wind on the front side of the system Friday into Saturday as there could be some gusts in the 20-30 mph range. Pending on how the trailing disturbances interact and siphon off energy from one another, gusts could increase on Sunday for the mountains in the 30-40 mph range with 20-30 mph elsewhere as the northwest wind increases.
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