The biggest snowstorm of the year (so far) has its eyes set on Connecticut. If you’re into measuring, be sure you have a yard stick. A 12″ ruler won’t cut it this time around.

The model consistency and agreement has been impressive. Since yesterday, most major models (GFS, ECMWF, NAM, RPM) have shown a big snowstorm.

A *Winter Storm Watch* is in effect for the entire state.

The graphic above is from BUFKIT. The data is from the 1pm run of the GFS model for Bradley Airport. Time goes from right to left. Yellow lines indicate temperature, red lines indicate upward motion, and the cyan line is the snow ratio (based on warmest temperature in the column).

The best snow growth should occur where the most negative red lines (greatest rising motion) coincide with the -12 to -18 yellow lines (temperature in Celcius). Notice that upward motion is greatest around midnight Friday into Saturday. This is why the heaviest snow is expected overnight Friday and into Saturday morning.

The cyan line is snow ratio. I have chosen the warmest temperature in column method. Even though it’s not labeled, the midpoint of the cyan line is a 15:1 ratio. This will result in a powdery snow that is easier to shovel than wet snow.

Now, all of this is gleaned from one model: the GFS. Models are not always right.

Below is my forecast, which is compiled using a combination of multiple models and experience.

1. TIMING

Expect intermittent light snow to begin around daybreak on Friday, with the snow becoming steady around 12 noon. The heaviest snow will fall from 6pm Friday to 6am Saturday. The snow will taper around 12 noon on Saturday. This is approximately a 24 hour event.

2. TOTALS

Most people will end up with more than a foot of snow in Connecticut. In northwest and northeast portions of the state, 2 feet of snow is not out of the question. Mixing will be an issue along the shore for several hours in the beginning of the storm. However, once the storm really gets going to our east, cold air will take over at all levels of the atmosphere and ensure everyone sees snow for the second half of the storm.

3. IMPACTS

Winds will be sustained at 25-35mph across the state during the height of the storm. Gusts could be higher than 50mph, especially closer to the water. This type of wind will cause power outages. At the same time, we have one thing working in our favor — the snow will be powdery in nature, with ratios averaging about 15:1. 

Travel will be crippled late Friday and early Saturday across all of southern New England. Plan to quit traveling and light the fireplace by noon Friday. After that, things won’t be safe enough to venture out until late Saturday or early Sunday (depending on how long cleanup takes).

4. BLIZZARD OR NOT?

According to the National Weather Service:

A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer:

• Sustained wind or frequent gusts to 35 miles an hour or greater; and
• Considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than ¼ mile)

We will come close. The best chance for blizzard conditions is in eastern Connecticut, closer to the storm center where winds will be strongest and snowfall rates could be highest.

Stay tuned for updates throughout the storm.