The Sun is shining. The birds are chirping. Half my front lawn is snow free. It’s so easy to think spring.
Not so fast, Bucko.
With snow, accumulation = intensity * duration. You can get a significant snow from a brief heavy burst or many hours of light snow. Odds are we’re getting the latter Wednesday morning through Friday morning. 48+ hours of precipitation seems likely!
As has been the case recently, the GFS and Euro disagree on most of the finer points.
The Euro is colder. Often I’ll look at the 850mb 0°C line–where the temperature at ~5,000 feet is 32° Fahrenheit. It’s an excellent rain/snow predictor. That line is farther south on the Euro, meaning we’re more likely to see all snow even on the shoreline. The GFS solution leans toward mixed precipitation for the first 12-15 hours.
I’d go whole heartedly with the Euro, except for the addition of the SREF (Short-Range Ensemble Forecast) model. Uh oh, another American model?
The SREF goes out 87 hours and has been optimized to,
address the aspects of winter weather events beyond accumulation – specifically duration, timing, and intensity.
The SREF is actually 21 slightly different models run simultaneously to produce an ensemble. Like its American cousin, the GFS, it’s leaning toward mixed precipitation for the first half day.
Truth is in both the Euro or American models, Wednesday’s precipitation looks light. Even as all snow we’ll get no more than a few inches by nightfall Wednesday.
By Thursday all the models come into agreement on Ptype (precipitation type)–Snow!
By this time the forward progress of this storm has been slowed to a crawl. The GFS shows the central low pinwheeling in place most of the day!
Here’s the bottom line: Mainly light snow inland, with light mixed precipitation on the shoreline beginning Wednesday morning. Accumulations by Wednesday sunset just a few inches inland. Travel Wednesday will be a little slippery, not terribly bad. However, the storm continues.
Light snow overnight Wednesday/Thursday with light to moderate snow continuing through late morning Friday (a little longer toward I-395). Thursday will be a more difficult travel day. Friday morning too!
Final accumulations 6-12″ inland, with highest amounts north of Hartford, in the hillier terrain Northeastern and Northwestern Connecticut and inland near the Rhode Island border. On the shoreline, 4-8″ with lowest amounts in the New London/Groton/Stonington area.
Remember, in this case ‘final’ isn’t until Friday!
More updates to come.