Seasonal affective disorder (SAD), also known as winter depression or winter blues, is a mood disorder in which people who have normal mental health throughout most of the year experience depressive symptoms in the winter . . . Once regarded skeptically by the experts, seasonal affective disorder is now well established. Epidemiological studies estimate that its prevalence in the adult population of the US ranges from 1.4 percent (Florida) to 9.7 percent (New Hampshire).

NECN Weather person Matt Noyes at 9 pm predicts the next wave of snow will begin between 3 and 5 am and will continue throughout the day tomorrow. He described a line running from Springfield to Worcester to Boston and said along and south of that line will have snow at first that will quickly change to a sustained period of sleet. North of the line, particularly along and north of Route 2, the precipitation will be all snow with 15 to 20 inches falling before it ends tomorrow night.

The Globe has a fun graphic that uses Shaquille O’Neal to put the total snowfall into perspective. As much as I like Shaq, I preferred the old Shelby Scott meter. For those too young or too new to the region to recognize the name, Shelby was a WBZ-TV news stalwart who wrapped up her 30 year career in Boston TV by doing live shots in the record-setting snowstorms we experienced in the winter of 1995-96 when the all time snow fall record of 107.6 inches fell. To put that in perspective, our seasonal November to April average is 41.8 inches. As of 6 pm tonight, Boston had received 64.5 inches.

Even with all the snow we’ve received, the road crews in Lowell have done a masterful job of clearing the streets but with the sheer volume of snow that has fallen, there’s just no place to put it. Snow banks have pinched in streets leaving barely enough room for two cars to pass and none for parked vehicles. High snow banks at intersections also block line of sight, increasing the chances of intersectional collisions. Because there are so few places to park, walking might be a better way to get around but with so few sidewalks shoveled, pedestrians are forced out into the already too-narrow streets, a dangerous alternative.

As for school, the robo-call arrived tonight just after 8 pm. According to the Lowell public school calender, classes were to end on June 10 but with the seven cancellations so far this winter, the last day of school has been pushed back to June 21 by my count. Our next storm is due to arrive on Saturday night, but Matt N says there will be another one hitting us next Tuesday night into Wednesday.