With a change of position of approximately 50 miles, Massachusetts can see a storm “minor inconvenience” or “coastline problem”. That is the bad math looming behind the next possible winter storm warning of the imminent weekend. And the cleanup is still new with a super snow producer in the east of Massachusetts and already the mind has shifted to a system that is yet days away to full development. It is not yet a single organized storm on the map at this range but rather individual fragments of energy scattered all over North America and has to connect when it wants to connect.
The old stuff is once more aligning with each other: and a great dome of high pressure is falling out of Canada to bring another dose of Arctic air, and a low is forming to the south and is tapping Gulf moisture. When the growing low gains strength in a short period of time off the Southeast coast, the ultimate result may be the type of intense ocean storm that pulls the heavy rain back into New England. It is not a question of whether there is a storm or not, but of the point of its center when turning northwards.
The forecasters usually pay attention to the “40/70 mark”, which is approximately 80 miles south of Nantucket. When cold air has been present a track close to that location may be a sweet spot of major snow on the southern side of New England. When storms and ocean air move westwards, the snow may be replaced by mixed precipitation, and tight and neighborhood-neighborhood differences in snowfall may form. Shoot it east and even the worst of the snow may remain off shore leaving the coast with a brush and far less inland.
Such differences in the tracks also vary the wind field. A more profound low usually increases the pressure gradient which is the source of the “blizzard” concern: not only amounts of snowfall, but wind caused snowouts and drifts that replenish the roads after plows have cleared them. A blizzard warning must have the visibility below 1/4 mile during a period or time of three hours or more and frequent gusts of 35mph or more accompanied by a large amount of falling or blowing snow.
This time there is the addition of coastal effects. It is a full moon during the weekend, and this increases astronomical tides. Such occurrences as king tides demonstrate how small shifts in low-water standings can drive saltwater into low-lying avenues and walkways and how a rise in the than-average high-tide can travel a foot or greater than the normal high-tide. Combine that with a robust northeast wind and wave action and vulnerable regions along the shore can even be flooded when the headlines are taken up by snowfall.
The forecast should be generalized first, and only then prepared. According to state emergency managers, lessening the preventable strain during and following storms, such as the literally tangible risk of overexertion when shoveling snow, which is a well-known cause of medical emergencies in winter, is also stressed. Blasting furnace and appliance vents is also important since snow-blocked exhausts may increase the risk of carbon monoxide. The recommendations of MEMA also emphasize the importance of ensuring that smoke and CO detectors are operational and backup generators and heaters are used properly as the fumes should not enter the rooms.
In the case of households, the sensible action is to use the coming days as setup time: open drainage access, clear access points as well as to create room in which more snow can be laid out. The stakes will depend on that narrowing of the track in models, which will increase the forecast oblience when the storm consolidates, and the stakes will increase with that slight change in geography that can change the map overnight.
