4:30 PM UPDATE: Snow Day 70% Delay 30%

Snow day chances upped, as expected, as this storm begins to come together.  The only reason it was not upped further in this update was because precipitation is moving slightly faster than many models have been forecasting.  Not yet sure whether that means precipitation moves out earlier than expected, but most short range models still have snow continuing through at least 8 AM tomorrow morning so I don’t believe it will make a significant difference in terms of back-end timing.  The exact end of snow will be difficult to forecast because there will be some banding that forms on the back end of the low pressure center as it strengthens and goes out to sea, meaning somewhere in the Northeast will likely see moderate snow through 9 or maybe even 10 AM.  As of right now, that appears to be New Jersey, meaning it will be harder for SWCT to have widespread amounts approaching a foot, but I would be surprised if that ended up happening anyways.

Anyways, I am just updating you on any small changed that I’m noticing either from surface observations or from the weather models.  So far the weather models appear to be fairly consistent.  I still see anywhere from .5-.65 inches of liquid to be the way to go for the region, with both the HRRR and RAP showing almost exactly an inch of liquid.  At the coast this is around 7 inches of snow and inland this will be more like 8 inches of snow, solidly inside the forecast amounts.  In the next update I may lower the coast as well because new guidance shows that the gradient could set up where the coast gets more moisture than inland, but I am not confident enough in that to change the forecast, and the RPM actually also has more moisture inland along with better cold air for more high ratio snow.

Whether it is 6 inches or 8 inches or 10 inches, it will still last until at least 7 or 8 AM, and it will be sticking on roads and causing a headache for crews trying to clean it up.  For these reasons a snow day is still forecasted and the chance has been raised to 70%.  Along with that are the winds and cold I outlined earlier and the fact that this storm is getting massive media coverage, which typically can add pressure to close schools as well.  Regardless, we are looking to see snowfall rates of an inch plus per hour that road crews cannot keep up with, which is by tomorrow morning they will still be playing catchup trying to clear roads and I just do not see any schools in Southwestern Connecticut being able to open.  Again, if for some reason there is a last minute trend towards less snow then delays come back into the equation, but I am still favoring snow days and the chance of a snow day will likely only continue to rise over the next few hours.

Some schools may actually make the call tonight.  Inland districts with hillier roads that close easier probably should make the call tonight as there is no scenario I can see where they open tomorrow.  Conditions are going to be bad no matter what way you look at it tomorrow, of that we are sure.  Plus, snow looks to break out in the next 2-3 hours across the region and that could also push superintendents to close in case they were doubting any forecasts published.

In terms of what models I am looking at and at what data, the 500mb trough in upper levels of the atmosphere looks to be neutrally tilted, meaning it is oriented due north/south.  In a few hours it looks to tilt slightly negative which will allow the low pressure at the surface to our south to strengthen quicker and pull up more moisture.  This is all expected, and is part of the forecast.  Again, exactly how much moisture and how quickly that trough turns negative will determine how much snow falls across the area.  The RUC/HRRR/RAP, the three main short range HD weather models, all seem to agree that the heaviest precipitation will be between 11 PM and 3 AM where an inch per hour+ snow can be expected and that total liquid amounts of around or a little over half an inch can be expected, which fits in well with the forecast.  I’m not seeing anything major in any individual run worth noting.  The storm generally looks on track.  The one thing to note is that within an hour of snow starting road conditions will drop considerably as all snow sticks, even on roads, and the snow looks to pick up in intensity pretty quickly once the initial band moves through.

That’s where we stand right now.  I’ll have another update in a few hours, and will of course continue live-tweeting any new information that I get regarding school closings and what the weather model shows.  Keep it here for up-to-the-minute information of how this snow storm will impact your backyard in Southwestern Connecticut.

3 responses to “4:30 PM UPDATE: Snow Day 70% Delay 30%

  1. I’m a teacher in Stamford. We have 100% chance of a snow day. There is no way Dr. Hamilton will have students attending school in such treacherous conditions of snow, wind, and freezing temps.

  2. Jacob, great stuff as always. Wondering if you would come on our web radio “stormcast” – at 6:30 p.m. or so – chat about your site, forecasting and this storm. Our 16 CT newspapers cover SWCT.

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