Frigid February: Active Weather Pattern Yields 3 Short/Medium Term Snow Threats

As the title suggests, we have 3 storm threats over the coming 8 days that I am focusing in on.  Each one has the potential to disrupt travel, and two out of the three look to potentially disrupt schools across Southwestern Connecticut.  This blog post will give a brief analysis of all three, the first being during the day on Monday, the second being Tuesday night into Wednesday, and the final being Saturday night into Sunday.  I will go over what is known and what is not known for each one, and when I expect to be able to have a detailed forecast for each one.  The Monday storm is the one that we know the most about as it is only 40 or so hours away, though in some ways we have a little more confidence about how the storm Tuesday night into Wednesday will play out.  I’ll go into all of that below, going chronologically with each storm.

The first storm on Monday has a decent chance of impacting schools, though I am not yet confident enough to issue any types of percentages.  This storm has really only become more defined in the past 24 hours, with confidence finally growing enough that it will impact Southwestern Connecticut for me to issue a forecast.  The going forecast, based on current modeling data, is for 1-3 inches of snowfall anywhere from a few miles north of the Merritt Parkway to I-84.  Anywhere from around the Merritt Parkway to the coast of SWCT should expect around 2-4 inches of snow.  Timing is still not certain based on divergent model solutions, but generally it looks like snow will start some time in the mid to late morning, anywhere from the 8-10 AM range or so.  It will start light, with moderate snow then kicking in either late morning or early afternoon.  Moderate snow looks to continue through 2 or 3 PM before the snow gradually winds down over the next few hours.  Again, we are only getting hit by the more northern portion of this precipitation shield, so I doubt that snow will last as long nor be as intense as areas further south, but up to 4 inches, with maybe areas by the immediate coast pushing 5 if there is a slight shift north, looks likely.  Any shift in low pressure movement could put certain areas in a longer period of slightly more intense snow, so I am watching closely for any additional northern shift in the precipitation shield, and if necessary I could be raising the coast into the 3-6 inch range and inland into the 2-4 inch range.  I do not see that necessary at this time, and there is about a 30% chance of that happening, but if it did then it would greatly increase the chances of snow days Monday across most of Southwestern Connecticut.  My current inclination is that morning travel to school should be no problem, but it is leaving school in the afternoon that could be impacting by poor road conditions.  Early Dismissals would not solve much as snow would likely be heavy around 12 PM or 1 PM than it would be at 3 or 4 PM.  This makes this one of those all-or-nothing scenarios where districts have to decide if a few inches of snow falling at the wrong time is enough to close schools.  For most, it likely will be, but I will have much more on this tomorrow once accumulations and timing are more nailed down, so check back in for percentages on that then.

The storm Wednesday is much more complex because it has heavier precipitation, will be longer lasting, and will likely have numerous precipitation types for Southwestern Connecticut.  Confidence is high that precipitation will start as snow across the area between 12 PM and 4 AM.  Snow will start light before picking up intensity over the next few hours.  By 7 AM, models begin to diverge.  They all agree that the region will be in the throes of very heavy precipitation, though they disagree on whether that will be rain, sleet, freezing rain, or snow.  A primary low pressure center moving to our west will be transferring one that will be moving northeast from our south.  What this means is the first low pressure center is pumping warm air into the region while the second one will stop the progression of the warm air and try to pull in colder air.  As a result, we get a very dynamic, complex atmospheric boundary layer that could support multiple types of precipitation.  If the low pressure center transfers energy sooner, there will be more cold air and almost all snow for Southwestern Connecticut, if it is later instead we would see more rain, and in between could result in an extended period of sleet or maybe even freezing rain (though freezing rain would likely just be inland).  Heavy precipitation will continue through most of the morning of then will begin to die down later in the morning and into the afternoon before eventually ending.  My current inclination is to believe the weather models that have been trending colder, such as the CMC/ECMWF, as most storms this winter have tended to trend southeast at the last second and allow slightly colder air in.  This means I believe that the majority of the storm could be snow for Southwestern Connecticut, and if this were to be the case we could be looking at anywhere from 6-12+ inches of snow.  I won’t be releasing an official forecast on this storm in terms of snow until tomorrow evening at the earliest, though it is likely the first true accumulation update won’t be out until some time on Monday.  Anywhere from a few inches of snow with a lot of sleet/rain to areas having over a foot of snow by Wednesday afternoon remains a possibility.  Regardless, due to the timing of the storm delayed openings across the entire region are a guarantee and it is very likely most districts will have to delay, as I do not see roads being drivable in any part of Southwestern Connecticut even by 9 or 10 AM and even if the storm turns over to rain and does not stay all snow.  This could change, but I think between Monday and Wednesday schools have the best chance of closing Wednesday, though I also believe many districts have a good chance of having to close both days.  If there is rain, temperatures fall back below freezing Wednesday night, leading to severe black ice problems and delays could occur on Thursday too.  We’ll cross that bridge when we get to it though.  I won’t go too much more in depth about this storm because the models have a lot to figure out, but I will continue to tweet/update about what trends show, and I expect they will continue to move towards a colder and snowier solution for most of Southwestern Connecticut.

The final storm threat that I am following is some time in the Saturday night into Sunday range.  This is the storm that at this time we know the least about.  It has the potential to be the biggest of the three, though it also has the potential to bust and have the least impacts of the three.  In many ways there is a similar storm set up to Wednesday, with one primary low pressure center moving to our west and another likely to form to our south and trap in cold air.  Models continue to diverge on whether the second takes over in time to result in primarily snow for the region or if enough warm air gets into the area to turn most precipitation to rain.  There is a lot of moisture with this system, similar to the one on Wednesday, so if this storm ended up being mainly snow and the jet streams phased at the right time to rapidly strengthen the secondary low pressure we could be dealing with yet another major snow storm.  If the jet streams do not align and the storm cuts inland or gets sheared out to sea we could end up with rain or end up with nothing.  At this time, I see a scenario where we get mainly snow maybe mixing with sleet and rain (more likely at the coast) being what is most likely here, but models continue to be all over the place and they won’t lock onto a single solution until the energy for the storm system moves over North America and we can get proper data sampling for it.  Stay tuned here as the storm moves into more of the medium and short range and confidence grows as to what impacts it will bring to the area.

CONCLUSION: That’s where we stand with the three storms.  Looking at 2-4 inches at the coast and 1-3 inches inland on Monday with the potential for schools to have to close due to snow.  If they don’t close, don’t expect the day to be shortened in any way.  As for Wednesday, we may have precipitation mixing issues, especially by the coast, that could limit snowfall amounts even though everywhere starts as snow early Wednesday.  Regardless, volume of precipitation and intensity of the storm will likely be enough to close schools (especially inland), though if not delays are a guarantee for the entire region.  Finally, the storm Saturday into Sunday has the most questions surrounding it, as it could be a large snow storm that could rival or beat Wednesday, or it could be mainly rain/be shunted mainly out to sea.  I will continue tracking all three storms and updating on the latest for all of them.  Throughout the day tomorrow I will be posting snow day percentages for Monday as well as sharing additional information for the two later storms as it comes in.  Stay tuned for the latest here at your most local weather source.

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