Sunday 3/12 Evening Update on Major Storm Tuesday

Good evening!

Here’s an update on the upcoming storm.

Precipitation Types

Locally, it’ll be all snow and for pretty much my entire coverage area it will be a fluffy snow. To the southeast, mixing will likely become an issue.

Hazards

Heavy snow, blowing and drifting snow, poor visibility with whiteout conditions, very dangerous travel, strong to damaging winds. Coastal flooding and beach erosion at the coast.

Timing

Snow begins very early Tuesday morning and quickly becomes heavy. This continues throughout the morning, and then the worst of the storm is Tuesday afternoon and evening when several inches of snow per hour are likely along with the worst of the winds. The snow then tapers off during the overnight hours.

Impact

Travel will be life-threatening with heavy snow throughout the day Tuesday. While the absolute worst of it will be Tuesday evening, heavy snow is expected throughout the morning as well. You should have any travel completed by about the time the morning rush hour would normally begin, and be ready to stay at that place for at least 18-24 hours. Contributing to the travel issues will be snow covered roads (to which plows may not be able to keep up with at times), along with poor visibility with whiteout conditions due to strong winds that will blow around snow, along with all the other joys of driving in strong winds. At times, just about any travel of any type is going to be nearly impossible.

Those same strong winds may also cause tree damage and power outages, especially at the coast where coastal flooding will also cause problems. Winds may gust up to 50 mph to the west and up to 60 mph in eastern portions.

Schools are virtually certain to be closed Tuesday, and probably on Wednesday too (to permit cleanup).

Snowfall Amounts

snow map 3-13-17 606p.png

A general 12-18″ is likely for most with scattered higher amounts. From the Worcester Hills and portions of MetroWest into the Merrimack Valley and southeast NH, amounts will probably be closer to 15-20″ and this is the most likely location for amounts of 20-24″. Note that this is our best estimate as to the jackpot zone and it could shift. Further south in southeast New England, less snow is expected with mixing likely along with warmer temperatures promoting lower snow ratios.

Uncertainty

Most guidance is in general agreement with the snowfall amounts, but there is still some haggling left over. If the track goes a bit more southeast, the 7-12″ zone may need to be expanded to include some western areas, while a track closer to Cape Cod/the Islands would push the rain/snow line more north – not enough to change the situation north and west of Boston, but from around there it might be a factor in reducing amounts. (Such a scenario may make the snow jackpot a higher number, too.) Also, as with any storm, there is the possibility of a dry slot forming somewhere. It’s not entirely clear where such a dry slot would set up – it could set up anywhere, and this includes what I am currently pegging as the jackpot zone (however, it is less likely to be in that zone). There is also a slight chance that the upper limit on the snow could inch a little bit higher, but this is unlikely. More clarity on the exact details should be around tomorrow morning.

Have a good one!

-Nathan

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