On Wednesday when we outlined scenario probabilities, we stated that there wasn't much daylight between a moderate/high impact event and a statewide blockbuster event. Since that time, we saw substantial waffling in the guidance. Yesterday, a westward trend began as the upper level evolution looked far more favorable for an efficient phase, and that trend accelerated last night.
It has been a roller coaster ride rarely seen around here, but with the continued overnight and early morning trend for a closer approach by the winter storm, we now have enough confidence to issue our final call.
It's a doozy.
At this hour, Winter Storm Warnings are up for the entire state, but it is my expectation given this morning's NWS discussion that the blizzard warnings that are up for coastal Mass will be extended into at least part of CT (most likely coastal and SE CT) at some point.
Regardless of whether you end up in a blizzard warning or not, we expect near blizzard to blizzard conditions (officially 3 consecutive hours of 35+ mph winds/gusts & 1/4 mile visibility) for much of the state (especially eastern areas) during the peak of the storm.
We are substantially upping our snowfall totals, with 6-12" expected in far western CT, 12-18" for central CT, and 18-24" for eastern CT.
Let's talk details.
Why are we going big? In essence, the main pieces we were looking at--northern stream, southern stream, and confluence in Canada--all trended enough in spacing and amplitude to allow for a much more efficient phase of the northern and southern streams, creating high confidence in the explosive development of a coastal storm.
Importantly, this also allows for the storm to track further west, rapidly intensify in a near perfect zone for New England, and slow down. That's a classic setup for a blockbuster.
We expect some light snow to break out in the state, most likely late morning/early afternoon. As GP noted yesterday, we don't expect much accumulation, but things could bring an inch or so. With cold temperatures that means slick spots are possible on the roads. That said, travel today and tonight should be fine. The time to avoid roads will be around daybreak Saturday, though road conditions will deteriorate in the predawn hours.
There is likely going to be a break late afternoon and evening before the main event arrives. The outer edges of the storm should arrive between 9-11pm. Note this is subject to change a bit but it doesn't really change things: travel should be ok during the evening.
Moderate snow will move in during the early morning hours, and by sunrise, much of the state should be seeing moderate snow that is becoming increasingly heavy.
The late morning and afternoon will be the worst of the storm. This has bounced around a bit, but I think this is the period we see the worst now. We will see heavy snow, strong winds, and some coastal flooding. Travel will be very difficult and near impossible in parts of the state due to very high snowfall rates and wind. Travel is not advised during this time.
Snow will gradually diminish during the evening, though significant travel issues are expected through at least part of Sunday.
Let's start with what everyone cares about. How much snow can be expected in your backyard.
This is a big storm.
Again, we expect 6-12" for western CT, 12-18" for central CT, and 18-24" in eastern CT. While 6-12" storms are a bit more frequent, widespread 12"+ storms are more uncommon than people think and 18"+ is even rarer. In this kind of storm there will be extreme banding. What does this mean? First, it means that there will be "winners and losers". On both the NW and SE of big bands, we will likely see some dry slotting, which could cut down on totals. In the big bands however, we may see very high ratio snow which means big totals that may come outside of our forecast range in localized spots.
We anticipate a gradient snowfall distribution. The further east you are, the better chance you have of being on the higher end of your snow total zone. The only exception may be extreme SE CT, where you already know your climo. Jackpots there are uncommon for a variety of reasons. Totals are expected to be very high there regardless.
Even with greater confidence, I must admit that this part is always nerve wracking. You can almost always bank on great snow banding northwest of the best frontogenesis. That's going to be a moving target even during the storm, so while we will be graded on our map, expect the unexpected with such a dynamic storm...in both directions.
Since we're using the dreaded B-word for this storm, that means winds are an issue. We expect max wind gusts between 35-45mph inland and 40-55mph at the shoreline. This is enough for near blizzard to blizzard conditions, but not enough in this forecaster's opinion to cause widespread damage.
As a result, we think power outages are scattered, and most likely to be concentrated in our usual windiest spots and SE CT.
Snowfall Intensity/Road Conditions
In order to get these high end snow amounts, the extreme banding mentioned above is going to have to drop some serious snowfall rates. The NWS mentions 1-2" of snow per hour in banding in CT, but I think that might be a floor, especially in eastern CT. That's big time.
The standard 1-2" per hour should verify but we could see 3-4" per hour rates at some location in CT during the height of the storm.
That means roads will be terrible, no matter what our great our plow drivers out there do. If we see the banding that we anticipate, the combination of strong winds, fluffy snow, and high snowfall rates will make travel hazardous to nearly impossible in spots with quick accumulations on the roads and very low visibility. If you need to travel during the height of the storm, be prepared in case you get stuck. I see it every big storm.
I think there will be surprises with this, but if things hold to our general forecast this is a high end event for CT, especially in eastern and parts of central CT. Fortunately, coastal flooding looks to be minor to moderate and the snowfall type looks to be fluffy and light, diminishing the risk of power outages. One thing not discussed yet is how cold this storm will be. We don't expect mixing and in fact, the cold source for this storm is about as ideal as you can get.
We will see temperatures drop through the 20s and into the teens tomorrow during the storm. With the wind picking up, we could very well see heavy snow with wind chills near to below zero. Take that into account while you travel. Even though we don't anticipate widespread power outages, today is the day to make sure your generator is working just in case.
This looks big across a lot of Connecticut, so while there is no need to panic, you do need to be prepared and smart, especially if you need to travel for some reason or have to shovel--people end up in the hospital each year overdoing it shoveling.
- There is high confidence that a major coastal storm will develop and deliver high end impacts to CT, including near-blizzard to blizzard conditions across much of the state.
- There will likely be a strong snowfall gradient, and high ratio snow. With high snowfall rates at the peak and strong winds, travel will become very hazardous to nearly impossible late Saturday morning through afternoon before snow tapers off during the evening hours.
- Residual widespread travel problems are expected, at least through early Sunday.
We will continue to provide updates as warranted.
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