Weather

Dave Epstein: Friday weather will be a mixed bag of freezing rain and sleet

"By noon, I expect freezing rain and sleet to be the dominant precipitation happening."

David L. Ryan / The Boston Globe


Changing weather and road conditions mean that by the time you read this, what you’re experiencing outside may already be different than what I’m writing about.

Friday is one of those days when dropping temperatures are going to dramatically affect road conditions. If you need to get into Boston and can do so by about 9 a.m., then stay in the city until the end of the day, you should basically miss the entire event. Roads won’t be bad early morning, and by the time you head home, they will have been treated.

Temperatures will fall into the teens by late Friday evening. – NOAA

Rain will transition to freezing rain this morning, with temperatures falling below freezing in Boston, certainly by mid-morning. By noon, I expect freezing rain and sleet to be the dominant precipitation happening. For those of you reading this on Cape Cod and the Islands, it’ll basically be a rainstorm with a little bit of ice at the end.

Advertisement:

A mixed bag of weather is expected during the middle of the day Friday. – WeatherBELL

If you’re wondering why so many schools threw in the towel, it’s because ice on untreated surfaces renders the traction we need to walk and drive pretty much ineffective. Ice doesn’t have a lot of friction, therefore even the best four-wheel-drive vehicles will not be able to stop as successfully as on dry roads.

Roads are expected to become icy Friday morning as temperatures fall below the melting point. – NOAA

You’re likely not going to be completely conscious of the ice on your walkway or steps. Take it very slowly when you walk outside to get the mail or take the dog out this afternoon. I can all but guarantee there will be people who fall because they’re not prepared for the ground’s traction to have disappeared.

Once temperatures get cold enough for sleet to develop, it will become easier to travel, but it’ll still be quite tricky. This is because the melting products that municipalities use will be more effective on sleet. Freezing rain tends to encapsulate those products, whereas salt, sand, and calcium can sit on top of the sleet and be more successful in their intended use.

There probably won’t be enough freezing rain to bring down trees and wires, but there can always be exceptions during these winter events.

Advertisement:

The amount of freezing rain forecast should not be enough to create power issues. – NOAA

The reason for this latest round of wintry weather is cold air arriving to ground level before it arrives at upper levels of the atmosphere. This means that snowflakes falling out of the clouds end up melting into liquid and then either freeze on contact with the ground or become little ice pellets that hit the ground. Either way, it’s a mess.

Waves of low pressure along a cold front will bring rain, freezing rain, sleet, and snow to the Northeast Friday. – NOAA

Temperatures will fall down to the teens overnight and remain in the lower 20s on Saturday with increasingly sunny skies through the day. Sunday will be very cold to start, with most areas in the single digits, and temperatures will rise to the 20s in the afternoon. Much of next week appears to me to be dry, and temperatures will be above freezing for a little bit of a welcome break in our active winter pattern.

Highs on Saturday will remain in the lower 20s for most of the afternoon. – NOAA

Daily Local Weather Forecast

  • Today August 09
    Partly sunny with thunderstorms
    Partly sunny with thunderstorms
    98° 67°
  • Wed August 10
    Intermittent clouds
    Intermittent clouds
    75° 67°
  • Thu August 11
    Showers
    Showers
    79° 64°
  • Fri August 12
    Intermittent clouds
    Intermittent clouds
    76° 62°
  • Sat August 13
    Intermittent clouds
    Intermittent clouds
    76° 64°
  • Sun August 14
    Partly sunny
    Partly sunny
    81° 65°
  • Mon August 15
    Partly sunny
    Partly sunny
    82° 66°

Conversation

This discussion has ended. Please join elsewhere on Boston.com