Heavy Snow Expected Tomorrow Morning

A major snow event will impact the region tomorrow.  Premium subscribers have been receiving email updates and forecasts regarding expected accumulation, timing, and impacts from the upcoming storm.  Below we summarize our latest Premium forecast in all those categories.  Additional forecast updates through the storm will be emailed out to Premium subscribers with parts posted freely here as well.  To read our more in-depth and frequent forecasts, subscribe here.  Otherwise, please enjoy the free forecast below:

Precipitation begins to break out late overnight into early tomorrow morning.  Isolated to scattered rain/snow/sleet showers will be possible between 1 and 5 AM overnight, but nothing all that steady is expected.  The main precipitation shield looks to move in from west to east between 4:30 and 7 AM based on the most recent guidance.  By this point all precipitation will be turning over to plain snow as the entire column rapidly cools and temperatures down to the coast fall below freezing.

The period of heaviest snow and most significant impacts looks to be 7 AM – 12 PM tomorrow.  In this timeframe, snowfall rates of up to 2-3 inches per hour are not outside the realm of possibility, with thundersnow also a possibility.  Up to 75-80% of accumulations are expected to come in this 5 hour window, indicating just how heavy snow will be in this timeframe.  All precipitation will be snow, and recent indications are that areas south of I-84 have the highest chances of getting into the heaviest banding in this timeframe as well.  However, steadier snow may be able to start just a bit earlier further inland thanks to better lifting with the higher terrain.  Models are mixed on how much of an advantage far inland areas may receive from this still.

Between 1 and 5 PM snowfall gradually winds down across the region from west to east.  Most significant accumulating snow will be out of the region by 1 or 2 PM, but wrap-around banding could allow for some lingering light snow showers through the afternoon as gusty winds continue as well.  Some blowing snow will be a possibility and could keep travel conditions poor through the afternoon as snow will end very light and fluffy with cold flooding in behind the storm.  Then overnight tomorrow night we will see temperatures drop into the single digits inland and low teens at the coast with wind chills down to around 0 degrees.  Snowcover helps to sustain the cold for one of the coldest nights of the winter.

The accumulation forecast is as follows: South of I-84 expect 8-15+ inches of snow rather widespread and around/north of I-84 expect 7-13+ inches of snow.  The “+” in each forecast highlights the potential for isolated amounts significantly higher in the strongest banding, as the dynamics with this storm are such that we are seeing a very intense amount of snow for a short amount of time, and widely varying accumulations are a real possibility.  Additionally, snow may be hard to measure due to its increasingly light nature and the increasing threat of drifting through the storm as winds pick up as well.  If anything, I may have to raise the forecast a bit inland, as some modeling guidance shows the potential for widespread amounts in the 10-12 inch range or higher there, but a couple models show the heaviest snow confined to the coast which seems quite possible given the expected track of the storm and best dynamics.  Snowfall ratios start around 10:1 but rise up to around 15:1 through the storm as cold air floods in behind the low pressure center.  Intense banding will allow for highest accumulations likely across southeastern areas, though it is exceedingly difficult to try and nail down exactly where the strongest banding will be.

Gusty winds are expected with the storm as well.  Strongest winds are expected at the coast, where gusts up to 40 mph are expected, while inland areas could see gusts up to 30 mph.  These gusty winds will create blizzard-like conditions at times in the late morning and early afternoon and severely reduce visibility while also allowing snow to drift.  At this point I am not too worried about power outages as the winds will not quite get to that level and the snow should be light and fluffy enough to avoid really sticking/accumulating to branches and power lines, but blowing snow into the evening tomorrow will be an issue.

Overall, travel tomorrow will be brought to a standstill as schools should close with major impacts from a strong snow storm.  The storm is quite intense but also quick-moving, preventing it from having impacts quite as severe or long-lasting.  At this time, the main questions revolve around exactly where we would expect banding to set up with the storm and what snowfall ratios will be like, as these will answer the questions of whether this is a moderate snow storm with accumulations in the 8-10 inch range or a major storm with accumulations in the 12-15 inch range.  The shortest-term model guidance should get in range this evening and help to answer these questions.

Light Snow Expected Tomorrow

The below update was part of a recent Premium forecast relating to a light snow event expected to hit the region tomorrow.  Minor travel and potentially school impacts are expected, as outlined in the forecast.  To see the potential school and travel impacts, subscribe here.  Otherwise, below is the forecast timing and accumulations for the light snow tomorrow:

Tomorrow will start partly cloudy with increasing clouds through the morning.  Very light snow showers break out across the region between 9 AM and 11 AM, likely remaining quite light into the early afternoon.  The largest change in short-range guidance has been to show that any snow through 1 or 2 PM will be quite light as over-running precipitation struggles to accumulate.  No more than half an inch of snow is expected through 1 PM now, with questions as to what exactly happens after.  Following that light snow, coastal areas could see a pause in snow between 1 and 3 PM as a dry slot moves across the region; light snow may still continue inland with slightly better orographic lift.   A moderate burst of snow between 2 and 6 PM is still a possibility though not a guarantee, as some modeling still shows almost all steadier snow further inland.  Then, lingering snow showers look to be a possibility through much of the evening, finally winding down between 10 PM and 2 AM.  We clear out from there into Wednesday morning.

Accumulation forecasts have become a bit more complicated as it appears the front end of the storm will bring a bit less snow than currently forecast.  It is hard to find evidence of widespread amounts of 2-3 inches like the National Weather Service is calling for, and even though there may be decent snowfall ratios this appears overdone.  Instead, I am calling for a coating-2 inches of snow regionwide now.  Most regions will likely see around an inch falling primarily in the afternoon and early afternoon.  Inland and far inland areas could still see isolated areas of up to 3 inches where the best lift is, but those look to be isolated much more so than widespread, as generally an inch or two of snow is expected.

Accumulation Forecasts Raised For Today’s Snow

In an email just sent out to Premium subscribers I highlighted the risk for more snow than was forecast across the area and have accordingly raised accumulation forecasts.  The latest forecast is available below:

Light to moderate snow is breaking out right on time across the region.  It will start light initially, though over the next hour or two we could get a couple of moderate bursts.  From there it will still begin to pick up in intensity between 12 PM with steady moderate to briefly heavy snow until 4 PM, with lingering snow showers through 8 PM.  Models overnight showed a slightly higher threat for bursts of heavy snow any time between 11:30 AM and 4 PM, with eastern and coastal regions the focus.  High ratios may allow snow that does not seem particularly heavy to add up rather quickly.  Snow should end by 9-10 PM across the region as the storm pulls out, though a couple models show a couple snow showers across New Haven through around 11 PM.

A snowfall gradient is still expected, though it may not be quite as sharp as previously expected.  Snow to liquid ratios up to 20:1 continue to look possible with the storm moving through, which is why I am becoming increasingly concerned about moderate accumulations into Fairfild County.  Later in the storm winds will pick up a bit so we could see some dendrite shattering more so by the coast (depending on exact snow growth regions) that may bring ratios down a bit, but at least 15:1 ratios seem reasonable throughout the entire storm.

The forecast has been tweaked with more location specificity.  5-8 inches of snow is expected in southeastern and coastal New Haven County, with 4-7 inches of snow expected across inland New Haven County and coastal and inland Fairfield County.  Far inland Fairfield County (north of I-84) can expect to see 3-6 inches of snow, as can costal Westhchester County, while inland Westchester County will see 2-5 inches of snow.  In this way the gradient is best reflecter, but overnight guidance shows less intense banding and moderate snow extending further to the west, increasing confidence that some of higher accumulations across New Haven County will be possible in Fairfield County as well.  Recent short-range guidance has shown the possibility of widespread amounts even further west of 6-7 inches of snow, so a slight tweak higher may be needed as the storm develops, primarily because of just how light and fluffy the snow is going to be as it adds up quickly.

Moderate Snow Threat Tomorrow

A chance of snow has sprung up across the region tomorrow as the precipitation shield of a rapidly strengthening low pressure center will expand further west than previously expected.  Premium subscribers received a detailed update earlier in the day and will receive coverage of the storm through the next 24 hours, while below we have listed our latest forecast:

Light to moderate snow breaks out between 9 and 11 AM across the region tomorrow morning.  It will start light, but begin to pick up in intensity between 12 PM and remain steady and moderate through around 7 PM.  Intensity will generally be light but some moderate pockets of snow will be possible as it does remain relatively steady.  Between 8 and 11 PM snow should wind down across the region, ending entirely overnight tomorrow night.

A rather sharp snowfall gradient is expected across the region, which is keeping confidence below average for this snowfall event tomorrow.  Models have shifted rather dramatically in the past 24 hours ahead of this storm, and with such short-term volatility we can expect some surprises to continue into the day tomorrow.  Short-term guidance is some of the most aggressive, showing that eastern areas could see up to 6-8 inches of snow, while global models show amounts closer to 3 or 4 inches.  One of the more complex variables is how cold it will be and thus how light and fluffy the snow will be again.  Snow to liquid ratios up to 20:1 may again be possible with the storm moving through, so even though liquid amounts will be less than half an inch we could still have moderate accumulations.  Later in the storm winds will pick up a bit so we could see some dendrite shattering (depending on exact snow growth regions) that may bring ratios down a bit, but at least 15:1 ratios seem reasonable.

Accordingly, I see the potential for 4-7 inches of snow to fall across New Haven County.  2-5 inches of snow is likely across Fairfield County, with 1-3 inches of snow expected across Westchester County.  However, the gradient may be a bit more sharp, meaning we could go from 6-7+ inches of snow in southeastern New Haven County down to just 1 or 2 inches in inland Westchester County.  A model consensus shows around 4-5 inches of snow across coastal Fairfield County with 3 inches or so expected most inland areas.  This all is based off of the latest guidance out over the past 2 hours, though again a shift of 20 miles either way could bump up or drastically reduce accumulations through the day tomorrow, and models remain in a bit of flux playing catch-up with this storm so if this trend west remains sustained I may need to upgrade Fairfield and Westchester County accumulation forecasts slightly.

Models Back Off Snowfall Expectations Overnight

Our forecast for light snow has been updated.  The updated forecast is available below, having just been emailed out to Premium members.  To view the updated school delay chances, subscribe here.  Otherwise, the latest forecast is below:

Light snow showers begin to move in across the region over the next couple of hours.  Steadiest snow is then expected between 1 and 5 AM, moving from west to east.  Between 5 and 8 AM we rapidly clear out, with the entire region dry by 8 AM as the sun attempts to come out by late morning.  Only an hour or two of steady snow is really expected in any one location as the storm remains very unorganized.

Current snowfall estimates have been updated to a coating-2 inches regionwide.  No longer does it look like much more steady precipitation will occur at the coast, and most models backed off the more impressive liquid amounts they had been showing this morning.  Interestingly, the National Weather Service updated the coast to a Winter Weather Advisory this afternoon which was in line with our previous forecast, but recent updates indicate that this may be overdoing it as I would be surprised for anywhere to see more than 2 inches.  Amounts closest to two inches are likely across coastal New Haven County, with generally an inch or a bit less expected across Fairfield/coastal Westchester County and even less expected across inland Westchester County.  No longer is an inch a guarantee even in coastal areas as steady precipitation looks to have shifted just a bit south, lessening impacts.

Minimal travel impacts tomorrow morning are likely for the Friday morning commute.  Of course, snow will be light, so impacts will be minimal, but slippery travel looks most likely between 3 and 6 AM.  Snow will stick instantly on roadways with cold temperatures, and though it may not be too icy and snow will not be heavy it may be hard for any sand/salt to melt much of the snow, so we could see slushy/snow-covered roads into around 7 AM.  Temperatures struggle to rise above freezing, so some snow could linger on back roads later into the morning.  Accordingly, just be slow to take it slow tomorrow morning, especially if you are out before 6-7 AM, though with only an inch or so of this light snow it is unlikely to have too much of an impact.