12 PM UPDATE: Wednesday: 55% Delay 45% Snow Day

This is the first update with regards to school on Wednesday.  I’ll also touch on a couple other trends I am noticing among the weather models, though my update from 9:30 covered almost everything that I wanted to talk about.

To start, I want to emphasize that this original forecast is very conservative.  I think it is likely that I end up forecasting a snow day for Southwestern Connecticut given the volume of snow expected to fall this afternoon, evening, and overnight.  However, at this time there is some spread in guidance that suggests that snow could only accumulate 5-6 inches and could be over by 2 AM, especially inland.  While a close call, this leaves the door open for delays instead of snow days tomorrow morning as there would still be numerous hours for clean up in such a scenario.  Yes, it is a close call, and for it to be this close out this far out likely means the chances of a snow day are going to increase and the chances of a delay are going to decrease, but I am not confident just yet to forecast widespread snow days.  The next update will come between 2 and 3 PM and if short range guidance comes into better agreement then I will be more likely too.  This really comes down to two things, each of which I only have low/moderate confidence with: total accumulations and end timing.  I’ll touch on each one of those below.

In regards to total accumulations, ranges are broad, at 4-8 inches inland and 5-10 inches at the coast, because of the very tight gradient this storm presents.  If the lower end of accumulations are met, it is very possible that schools will only need to delay tomorrow.  If the higher ranges are met, though, we would likely be looking at almost every school district or every school district in Fairfield County and likely surrounding counties closing.  As of right now I am very comfortable with my accumulation amounts and I do not see any reason to change them.  If I had to guess, most coastal areas will see 7-8 inches of snow with inland areas more in the 5-6 inch range.  This leads me to lean towards snow days but I would need a little more confidence and I want to see the storm develop a little more to be certain.  Where this banding sets up between 4-7PM will also be crucial to determining who gets the most snow and thus who has the most plowing to do overnight into tomorrow morning.

End timing has actually proven much harder to forecast.  There remain two weather model camps, though they are beginning to converge on one solution.  The NAM and now the GFS show most precipitation winding down by 2 or 3 AM with only an inch falling after midnight.  The RGEM holds onto precipitation a little longer but it is so light that it basically ends precipitation by midnight.  In these scenarios, and especially the RGEM’s where it trended south and gave the region less precipitation, schools would be able to open because there would be abundant time overnight to clear and prepare roads, and delays would likely be sufficient.  However, other guidance, such as the RAP, indicates that as the storm rapidly intensifies there would be backbuilding, which is where the precipitation shield around the low pressure center expands back to the west or holds on for a period of time to the west even as the low pressure center moves east.  The RAP thus has snow continuing until 4 or 5 AM, and in some cases that snow would be steady.  If this were to be the case, then again all school districts would have to close, even if they only got 5-6 inches.  I will be monitoring this very closely and observing/reporting on RAP runs as they come out as well as looking at real time observations as to when exactly the precipitation is expected to stop.

So those are the two things I am following now.  I want to emphasize that short range guidance is indicating that between 4 and 7 PM we can expect a very heavy band of snow to move through Southwestern Connecticut that could bring visibilities down below a quarter of a mile, contain thunder and lightning, have snowfall rates of 1-2 inches per hour, and pull down some gusty winds.  This will likely be the most dangerous part of the storm as snow will gradually keep picking up in intensity until it is very strong.  Anyone on the roads could be caught off guard and snow will pile up very quickly even on treated roads.  It is of the utmost important that everyone get off the roads by 2 PM if at all possible so that when the heaviest banding moves in between 3 and 4 PM crews are able to treat roads and try and keep them safe.  I worry about the timing of this band because it is coming right in the middle of the evening rush, which means it could cause even more traffic chaos than usual.  If at all possible try and avoid that chaos and get home by 2 or 3 PM.  As you look outside by 4 or 5 I am sure you will not regret it.

That’s the latest from here with the trends I am following with this storm and how it could impact school tomorrow.  I’ll have another update likely between 2 and 3 PM and they will continue throughout the day as I update the delay and snow day chances for Southwestern Connecticut.  Make sure to keep it here for the latest and most local weather news as this storm blows through.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>