Drying out with less wind, but we stay mild

PROVIDENCE, R.I. (WLNE) — The heaviest rain has ended, but it’s been a soaker! We’ve accumulated over an inch for much of Southern New England overnight.

We’ll have a few more spotty showers but the trend is to dry it out this afternoon. Highest wind gusts were realized in the pre-dawn hours. We’ll see wind speeds lighten through the afternoon. It will stay mild through today with colder air arriving tonight.

No surge of arctic air expected in the next seven to 10 days, however, a colder pattern with the chance for snow may be in the offing for the last full week of January.

Rain will end by mid-morning and as the cold front pushes through later today, we’ll see temperatures begin to drop this evening.

This evening, wind will diminish and temperatures begin to drop.

We’re watching a developing ocean storm over the weekend. This will keep us in a cool northeasterly flow of wind

and bring the chance for mixed snow/rain to Cape Cod and SE Massachusetts. Rhode Islanders will likely remain in the clouds with dry conditions on Sunday, but it bears watching.

This Afternoon: Scattered Light Showers, but trending drier.  Dropping temperatures into the 40s by evening. Gusty wind ending. Wind S shifting to WSW 15-25 mph.

Evening: Mostly Cloudy and Breezy. Temperatures falling through the 40s. Feels like 30 with the wind.

Tonight: Mostly cloudy. Low near 32.

Saturday:  Mostly Cloudy. Highs upper 30s. NW wind 10-15 mph. Feels like upper 20s.

Sunday: Mostly Cloudy. Flurries likely. Light snow showers southeast MA. Steady Snow on Cape Cod. High near 36.

Martin Luther King Jr. Day: Sunshine Returns High near 38.

Tue – Wed: Sunshine. Warming into the 40s.

Hydro what? Meteorologists study hydrometeors, hence, where the name comes from. Hydrometeor (a water meteor) is just a scientific way of saying precipitation. Most precipitation begins as snow/ice crystals in clouds. As this snow falls, it encounters a variety of temperatures. It can fall through a warm layer, then cold, then warm again and vice-versa. Meteorologists look at the three-dimensional atmosphere using data from weather balloons and computer models that use physics to create a future result, or a forecast. It’s ultimately up to the scientist to determine what will happen. Will it rain? Will snow survive the fall from the cloud? Will the snowflakes melt, then refreeze? If it refreezes in the air before reaching the ground sleet pellets are created and if it rains and surfaces are very cold, below 32 degrees, that rain can freeze on contact and that’s the most dangerous condition; freezing rain. Icing is extremely dangerous and can accumulate on trees and power lines creating power outages. There is a chance for this type of precipitation today and especially tonight in Worcester county.

The forecaster needs to determine what type of precipitation will fall. With the information age, there is a multitude of data sets, computer generated forecasts, and weather data analysis at our fingertips. Looking for the temperatures at several layers of the atmosphere, and something we call ‘thickness’ of the air helps us determine if snow will fall. One key temperature is the 0 C temp at 850 millibars which is around 3000 ft above the ground. Generally a snowflake can survive a drop of 2000 ft into air above 32 F. How much snow will actually be measured? There’s a lot that is considered. Ground/soil temperatures, amount of insolation (sunlight) prior to a snow event, solar angle at the time of the snow, pre-existing snowcover, dry air intrusions in a storm, warm layers above that may change the snow from fluffy to sticky and of course how much actual precipitation will fall from the cloud.

Typically, a 1 to 10 ratio of liquid (rain) to snow is average, but the ‘fluff factor’ can create a 1 to 30 or even 40 ratio. This happens in the arctic where the air is very cold. The snow crystals (dendrites) that form stand on end with each other and there is a lot of air in between them when they land.

For more on snow science, visit this National Weather Service page!

https://www.weather.gov/apx/snowflakescience

So, an inch of liquid could give you 3 feet of snow! This isn’t typical, however. Generally an inch will yield about a foot of snow. In spring and fall, mild layers of air or mild air near the ground can give you as little as 5 inches of snow per 1 inch of liquid. This is also not typical. Another factor is whether the snow will melt as it hits the ground and for how long during the storm. When will it ‘stick’? That’s when it begins to accumulate. Ground temperatures are very important in determining this.

Bottom line, there are a lot of factors to determining what type of hydrometeor will fall and then how much of it will accumulate and it’s NOT easy!

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