Our focus in the discussion this evening is on our coming storm, which is now onshore and brought snow to Seattle and much of the Pacific Northwest today. The much discussed pattern has produced, but rather than snow in our region, it is sparking what one National Weather Service Office is calling a generational type winter storm for areas to our west.
The timing for this one has remained consistent. Most of Thursday looks overcast and dry during the daylight hours. As we get to later in the afternoon and early evening, showers should begin to move in from the southwest. I don't expect anything too heavy at the start, which should be between 2-6pm. Travel on the roads Thursday look fine. Airline travel will likely be a mess across the nation.
The precipitation will be relatively slow to move in, but it's the overnight hours and into Friday that we see the heaviest rain and strongest wind. It looks like Friday morning will have the heaviest rain, while the strongest winds may come later in the day as a powerful Arctic front approaches.
Early Friday may have the worst travel conditions with heavy rain and wind, and some of the guidance is starting to show that Friday afternoon in advance of the front will have less heavy precipitation or even a break.
However, the Arctic front will mean business, and is likely to pass between noon and 4pm. Temperatures in the 50s will drop rapidly, likely being below freezing between 3-7pm. This means that we need to watch out for icy spots across CT as the sun sets.
The storm will depart Friday evening, and while some of the guidance tries to keep some moisture around as the Arctic front passes and bring a brief period of non-accumulating snow, I'm not buying it yet.
This is likely to be a high impact storm in the region, especially if you are considering travel during the Friday time period. There are multiple hazards with this one, and I will take them in order of impact.
Strong to Damaging Winds--High Impact
This is the biggest hazard with the coming storm, but it's still unclear just how much we mix down the strongest winds aloft. I still believe that the majority see peak wind gusts on the order of 45-55mph, but there is potential for isolated gusts up to 65mph, especially in eastern and coastal CT. I still don't have the highest confidence in that occurring, and will want to get closer to the event before going with those highest numbers outside of isolated spots.
As it stands, however, we are looking at an event that will bring isolated to scattered power outages, that would be more scattered to potentially widespread if we see 65mph gusts. That makes this high impact, especially with the holidays approaching. Again, highest winds are on Friday.
Flash Freeze--High Impact
For this impact, while I don't have high confidence yet that we see a true flash freeze, the potential is very concerning. As mentioned above, the Arctic front will quickly drop temperatures. While it's possible the break in the rain during the day allows for things to dry out, we could see black ice develop if roads remain wet as the front passes or if there's snow falling as the front passes.
The other issue is if you combine temperatures late Friday into the weekend dropping to the teens and single digits with bitterly cold wind chills and power outages, you have other issues right at home.
If you are on the roads while the temperatures drop in the afternoon and evening, be especially careful as it only takes a little ice to cause major problems for motorists.
Coastal Flooding--Moderate Impact
We have coastal flood watches for the entire shoreline for 1-3 feet of potential inundation late Thursday into early Friday. Fortunately, the impact here looks more limited, but for those right at the coast this could be impactful if we see higher end flooding.
Heavy Rain/River & Stream Flooding--Moderate Impact
We're going to see heavy rain on the order of 1-3 inches, and while that by itself is unlikely to cause major issues make sure those sump pumps are ready as most of it will likely fall in a relatively short period. As a result of a widespread heavy rain event, there is the chance of river and stream flooding. One item from the NWS this morning caught my attention--models are showing a 30% chance of the CT River seeing a moderate flood. That is a low likelihood, but would be extraordinary given the current water levels. That's something I'll be watching.
One final thing to note is the post front temperatures for Christmas Eve and Christmas. This is going to be a cold (and dry) holiday weekend. Expect temperatures struggling in the 20s during daylight with breezy conditions leading to very cold wind chills. Although it'll likely be a non-snowy Christmas, at least it'll be cold?
It's hard to overstate just how uncommon this cold and snow (not here) is. We're looking at a fairly rare combination right around Christmas that will impact most of the continental US. Of course, rather than a winter wonderland the Grinch is visiting our neck of the woods, but this is really likely to be one of the biggest storms the US has seen in a long time.
Thank you for reading SCW.