11:15 PM FINAL CALL: SNOW DAY: 60% EARLY DISMISSAL: 15%

The first snow day for Southwestern Connecticut is officially forecasted.  After consulting all of the latest computer models, I have decided that conditions will be bad enough throughout the region that schools should close tomorrow, not because of conditions in the morning but because of conditions in the afternoon when schools are let out.  Over this blog post I will go through yet another updated forecast and then explain how that impacts school.  This will be the final blog post for the evening, though expect updates throughout the day tomorrow both on Twitter and on this website as the storm develops.

Snow is still slotted to begin between 7 AM and 8 AM, which is one of the few parts of this forecast that have remained constant.  At onset, snow will not be too heavy, but it will stick on contact as both upper levels of the atmosphere and the surface will be significantly below freezing.  In fact, snow will start very powdery and light, which can sometimes make roads even more dangerous as it sticks immediately to the pavement.  By 10 or 11 as snowfall rates begin to pick up and around an inch or two of snow is on the ground it will become significantly more wet and less powdery, but it will still be below freezing everywhere except the immediate coast (anywhere south of I-95, that is) and thus will have no problem sticking to the roads.  I expect 2 inches on the ground by around noon, with 3 inches of snow on the ground by 2 PM, and up to 4 inches on the ground by 4 or 5 PM when the first round of snow winds down.  I am hereby updating the forecast to include a general 2-5 inches of snow for the entire forecast region.  I don’t think 5 inches will be widespread, but I think there could be enough reports above 4 inches that it is worth extending the forecasted amount, especially as snow could very well continue past 4 or 5 PM due to interactions with other upper level energy that will happen in the evening.  More on that in a second.

So I’m going to first focus on what the snowfall between 7 AM and 4 PM could mean for schools, then I’ll focus on potential snow after 4 PM.  So road conditions will start to go slightly downhill between 8  AM and 9 AM, but snow will still be light and road conditions will not be bad enough to justify closing schools at that time.  If the back end of the storm had not been extended and heavier snow were not coming later, I would not have forecasted schools closing.  Instead, I see road conditions beginning to get worse than expected around 11 AM or 12 PM when a band of moderate snow moves through with rates around half an inch per hour.  The RAP and the NAM agree on this, with the HRRR a little behind but in general agreement with the pattern here.  With 2-3 inches of snow on the ground by 1 PM and surface temperatures below freezing, it is very likely that road conditions are icy, slick, and in many places white.  Another inch or two of snow is then possible through 3 or 4 PM, meaning that by the time schools let out a decent amount of snow will be on the ground and roads will not be in safe conditions to drive through.  Almost all models agree that roads will not be safe come 2 or 3 PM, which is why there is a 75% chance overall that schools do not let out on time.  However, they will be going downhill by around noon at the latest, so Early Dismissals do not make too much sense here either.  The safest call is to close schools and expect for the worse road conditions later in the afternoon.

I have a few hesitations with forecasting snow days across the county.  The first is that there was a similar forecast like this last week that busted.  I specifically did not forecast a snow day then because I realized that there was a high bust potential and I did not expect roads to be that bad.  This time is different.  With surface temperatures below freezing and snow on the ground, roads will be icier and more dangerous.  While I do agree that schools maybe should not have closed last week, I see more of a threat with this storm that warrants them closing, even if superintendents are wary.  I have the 60% there to signify that schools SHOULD close, not that they WILL.  In fact, there is a chance that a few districts will try and tough out this storm because 2-5 inches does not sound like a lot of snow.  But when it falls at the perfect time, it can make roads extremely slick and dangerous, and that is exactly what looks to happen here.

My other concern is that the media will not relay the proper forecast with this storm.  In the past 2-3 hours, the timing of this storm radically changed.  Most media outlets have not yet picked up and reported on this, and I assume that most superintendents are not aware of this fairly major forecast change.  If they are not properly informed tomorrow morning, they may open schools thinking that conditions in the morning are not as bad as was expected.  They would be right, getting to schools may not be too bad tomorrow, but it is the conditions getting kids home that will be the bigger issue, and that is why I am arguing that schools should close.

Of course, as I did above, I gave my reasoning and I gave a forecast in terms of conditions. It is up to you to determine if you think this is enough to close your school district, as each district has a different policy it seems, but I do think in general most districts will close tomorrow, as they should.

This post got longer than I expected, so I’ll briefly hit on the idea that some upper-level energy interacts with the departing low pressure system.  This could enhance light to moderate snowfall through tomorrow evening and maybe into the overnight hours and add an additional inch or two to snowfall totals.  This is looking increasingly likely, and this means snowfall totals could be raised to 3-6+ inches for the entire storm vs. the 2-5 inches they stand at right now, but I am not confident enough to forecast that yet, and even if there is interaction I think most totals will end around 4 or 5 inches.  Still a sizable amount of snow, and coming at the right time it should close schools.  There is an outside chance of delays on Wednesday too, but at this time I find that very unlikely.  I’ll report on that more tomorrow

So that’s what I’m seeing with this storm.  As I have said, this is an extremely, extremely complex storm where every model run shows something completely new.  I am doing my best to keep you ahead of it and every and all changes that I see.  Likely it will not act just as forecasted here, but try and do something new tonight.  This is a VERY LOW CONFIDENCE forecast, and I could bust on either side of the forecast.  I honestly have no idea which side.  In forecasts like this, where surface temperatures are cold and we know accumulating snow is coming, it is best for districts to play it safe as there is a potential for very dangerous conditions tomorrow.  I’ll keep you updated as best I can.  Make sure to keep checking in for the latest, and I’ll continue updating on Twitter.

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