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.