A Blizzard Warning is posted for the area through Monday night. Here’s a breakdown:
Overview: Low pressure is taking shape east of the Mid-Atlantic shore Sunday morning and will organize through the day, gradually strengthening east of the Delmarva Penninsula. Tonight this system will undergo rapid strengthening as it begins to wobble east-northeastward away from the Mid-Atlantic coast. By Monday morning, a powerhouse storm – on the order of 965 mb (28.50″ on the home barometer) – will be spinning south of Cape Cod, tracking just outside the traditional “40N/70W Benchmark” position. The system will track northeastward from there, nearing Novia Scotia Monday night.
Snowfall: Light snow will overspread the area after sundown today and quickly become a steady snow during the first half of the night. Snow will pick up in intensity after midnight, with bands of heavy snow developing during the pre-dawn hours and continuing into midday Monday. Snow will continue to fall through Monday afternoon and evening, diminishing in intensity with time. Total snowfall will be on the order of 1 to 2 feet across the Cape, with drifts of 4 to 6 feet in spots. Through the first half of the storm, temperatures will be hovering in the lower 30s, meaning snow will be heavy and wet for an extended period of time. Some raindrops or sleet pellets could mix in with the snow at times from Harwich to Chatham to Eastham and Wellfleet, but the majority of the precipitation should be in the form of snow.
Wind: Damaging northeast winds are likely – especially with the weight of the snow factored in. East and northeast winds will freshen through the day Sunday, becoming a gusty breeze by evening. Winds will start to ramp up during the first part of Sunday night and transition to a howling northeast wind after midnight. Wind gusts to 60 mph will develop during the pre-dawn hours and continue throughout most of the day on Monday. Gusts to 70 to 80 mph are likely in spots, resulting in tree and limb damage and numerous power outages – which may linger for quite some time. Wind gusts will come down Monday evening, but it’ll remain quite gusty through the nighttime hours.
Coastal Flooding / Beach Erosion: A 3 to 4 foot storm surge is expected, which will yield widespread minor coastal flooding and pockets of moderate coastal flooding around the area at the times of high tide. The inside of Cape Cod Bay from Brewster to Sandwich will be particularly vulnerable during the day on Monday, with substantial erosion expected. For the east-facing Outer Cape beaches from Chatham to Provincetown, the combination of high tide and wave heights of 20 to 30 feet will result in extreme beach erosion in the traditionally vulnerable spots.
Power Outages: There is a high likelihood of power outages across the Cape and into parts of Southeastern Massachusetts with this event. Given the heavy wet nature of the snow and prolonged period of very strong northeast winds, tree, limb and power line damage will be common. Utility crews may very well struggle to address these issues until Monday night and Tuesday so the best course of action is to plan for extended outages and hope for the best. Charge your cell phone / devices, have batteries and flashlights at the ready, and make a plan to stay warm as it will turn sharply colder Monday night, with temperatures falling into the 20s.