BOSTON (CBS) – Ice is no fun.
I’d take snow any day because of what happened Friday morning. As the temperatures dropped and fell below 32 degrees, the accident reports grew more and more. The roads that were once wet, became treacherous in a matter of minutes. Sidewalks, driveways, steps, all untreated surfaces became skating rinks. If it hasn’t happened at your house yet, it’s coming.
Cold air doesn’t just spread across the area in a straight line from north to south. When it first arrives, the cold layer is shallow (cold air is dense and sinks), so it literally percolates down mountains and slopes and fills valleys first. The first few hours are always the most dangerous. It looks like it’s still raining, but the water freezes on contact with the now cold surface (roads, driveways, etc.). With the ongoing rain, it’s impossible to pretreat the roads, so it becomes a race against time for crews to sand and salt out the newly formed ice.
As more and more cold air seeps into our region, eventually the layer of cold air gets thicker and higher. Therefore, raindrops fall at sub-zero temperatures for a longer period of time. This causes ice pellets called sleet to form. And this is what we are seeing today. A short period of dangerous freezing rain followed by a change in those ice pellets. Sleet will collect a little but will NOT collect on surfaces like freezing rain.
As cold air continues to fill in, the entire “column” of air will eventually be cold enough for snow. This may happen quickly enough (before the precipitation stops) north of Boston to produce some scattered snow showers and blankets on Friday afternoon and evening.
Nearly all areas north of the Massachusetts Turnpike are below freezing as of noon and by 4 p.m. most of Norfolk, Bristol and Plymouth counties will drop below 32 degrees. Finally, last but not least, between 4pm and 8pm the Cape and the islands freeze.
Precipitation becomes heaviest between 4 and 8 p.m. and between 8 p.m. and midnight, the few remaining showers are in far southeastern Massachusetts, with only a few very light pockets of freezing drizzle elsewhere.
I imagine that for the afternoon drive, most of the main roads will have some kind of ice treatment, which will make traveling a bit safer. Still, I’d keep my speed down and certainly be careful on back roads, overpasses, and typical colder spots.
Temperatures will continue to drop overnight in areas of the teens in the north and west of Boston, 20 below zero in the south and east.
We didn’t get much back at all on Saturday. Afternoon highs will remain in the 20s and 20s despite receiving a lot of sun. Not much changed on Sunday, the entire region was still stuck in the 20s, below zero. Thanks to some sunshine, despite the cooler temperatures, some of the exposed ice will melt a bit during the day this weekend, so you may be able to wear down your driveway a bit.
Finally, next week looks relatively calm, just what the doctor ordered. Just a small chance of some showers brushing past eastern Mass. Tuesday, otherwise temperatures will be mostly in the upper 30s and 40s.