10 PM UPDATE: 50% Snow Day; Major Timing Changes

I’ve been talking on Twitter about how tricky these storms can be in regards to timing, and we are seeing an example of that right now.  Recent weather models still have the same start time for snow, between 7 and 8 AM, but instead the snow remains light in the morning with the heaviest snow now moving in between 12 PM and 2 PM.  Snow may not end until 4 or 5 PM now.  So instead of just the morning rush, we are having to worry about the drive home from school too.  And with snow throughout the day, an Early Dismissal does not make much sense as an inch of snow is still likely by 11 PM and two inches are likely by around 12:30 PM.  4 inches is becoming more attainable with what I am seeing, and I think the forecast of a total of 2-4 inches with isolated regions of 5 inches away from the coast further to the east are still possible as well given what models are spitting out.  The 0z NAM (especially the HD version) and the new RAP (the most accurate 18-hour high resolution model) are the two that have really extended the timing of the storm, and I am agreeing with what they are showing as it does seem to fit the dynamics of this storm.  A storm of more duration that will drop widespread amounts of 2-4 inches with maybe even a little more is thus more likely to close schools by impacting both the compute too and the compute from schools.  It is amazing how the storm seems to get going right as schools open and will just start winding down right when schools are closing, basically perfect timing for schools to close.

Accordingly, I bumped up the snow day total.  I think it is very likely that a majority of school districts close in Southwestern Connecticut, and I am more in favor of a snow day than I have been at any part of this storm.  Surface temperatures will generally be staying in the 20s per the latest HD NAM, and that means that snow should easily be accumulating on roads, making them even worse than they already may be due to black ice that has accumulated over the last day or two.  With roads bad by 8 or 9 AM and now likely even being worse between 2 and 4 PM, I think it is reasonable to think that most districts close.  The final update at 11 PM will state for sure whether I am forecasting widespread closures or not, but it is definitely becoming increasingly more likely based on the trends I have seen in the last hour.

A quick reminder that again, with storms like this, things can change very quickly and a trend back in the other way is possible too.  Storms that are regional, such as this, are harder to forecast without models, and thus reliance on models is higher and variance is higher.  That is why we are seeing these swings in forecasts close in, because this is not a large scale storm that models are handling well, but instead a smaller mesoscale feature that I am trying to track closely because it will have significant impacts in the region.  I will continue to watch this and keep you updated, so keep it here.

Before I publish this, I just want to quickly summarize the newest forecast.  I’ll be updating it on the side bar shortly.  I see a general 2-4 inches of snow (may be updated to 3-5 at the 11 PM update) with isolated amounts up to 5 inches possible away from the coast and away from the New York border.  Snow starts between 7 and 8 AM and gets heaviest between 12 PM and 3 PM, likely ending around 4 PM or by 5 PM at the absolute latest.  Snowfall rates could approach an inch per hour for an hour somewhere in the 11:30-2:30 range tomorrow, but generally snow will be light to maybe moderate in the 3 hour slot stated.  Temperatures with generally be in the mid 20s inland and upper 20s at the coast at the height of the storm, so all snow should stick, and mixing may be an issue at the extreme coast (south of Interstate 95) keeping down amounts a little less there, but other than that I do not expect  much mixing.  Stay tuned.

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