Dangerous Travel Expected Friday Afternoon/Evening

Premium subscribers have been made aware of the threat for light to moderate snow accumulations tomorrow afternoon for the last few days.  Below is the relevant portion of the forecast detailing accumulations and timing of the storm as it moves into the region for tomorrow.  Should you be interested in the potential travel impacts or the chances of school impacts, you can purchase the detailed Premium forecast here or subscribe to receive email updates with every forecast change here.  If not, the relevant portions of the forecast are attached below:

The forecast accounts for all of the most recent model trends that have been explained to Premium members; more snow is expected at the coast and in western areas than inland areas, and as the NAM shows at 5 PM tomorrow here coastal areas won’t be much warmer, if at all, than inland areas.  Thus, fairly consistent ratios, except maybe in coastal Westchester County, can be expected across the entire region.  Similarly, western areas look to see more accumulations than eastern areas; Westchester County will see more liquid equivalent than New Haven County.  The GFS does not show that, but the RGEM shows that well here.  As such, New Haven County will host lower snowfall overall I expect than Westchester County.  This creates an interesting gradient for the revised snowfall accumulation forecast.  I am now calling for 1-3 inches of snow falling across all of New Haven County along with inland areas of Fairfield and Westchester Counties.  I am increasingly struggling to see how inland areas see enough precipitation to get over 3 inches of snow, especially with most if not all snow falling during the day and thus not having as impressive snowfall ratios (thinking 8 or 9:1 right now).  Coastal portions of Fairfield and Westchester Counties can still expect to see 2-4 inches of snow, but again this may be revised down to 1-3 inches this evening depending on model trends this evening.

Essentially, this storm is running into impressive confluence further north as the Clipper on Saturday moves into the region, and this cuts off moisture as the storm proceeds and causes it to slide further east, not coming quite as far north.  This was a concern I have had for some time, and though models seemed to be going against the idea yesterday, they have been trending back towards it today.  I don’t think they are completely done trending today, which is why I have cut accumulations so significantly inland/across New Haven County.  However, there is a chance that these southern trends continue even more and we are stuck looking at as little as 1-2 inches of snow across the entire region, or some regions being dropped to a coating-2 inches.  It is too early for me to do this with any confidence, but these storms later in March that just are not strong enough to bring heavy snow can very easily bust due to the more impressive sun angle and the tricky nature of determining the exact track.

With the accumulation forecast changing, the timing forecast has been slightly updated as well.  Snow still looks to start between 12 PM and 2 PM now across the entire region.  Heaviest snow can be expected between 2 and 6 PM, with snow winding down between 7 and 8 PM.  Very few models now have any precipitation falling after 7 or 8 PM, and road conditions should improve from there.  It may also take a little while for the snow to start accumulating, so although it starts falling around noon in western areas it could take until 1 or 2 PM to start sticking on non-grassy surfaces.  Still, temperatures below freezing and the threat of moderate snow means it is likely that snow eventually sticks to all surfaces, although it should be quite slushy.  Thus, this really is just a quick 6-8 hour burst of snow, quickly moving out of the region by Friday evening.


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