The timing couldn’t be worse - a nor’easter on the busiest travel day of the year. The question now is how close to the coast will it track and how much snow will we see.
It’s a juicy storm with origins in the Gulf of Mexico. Both the European model and GFS model show a substantial storm nearby.
The European solution – with a strong storm hugging the coast is the solution is the one I think is most likely to verify. About half of the European ensemble members show a low track just south of Long Island.
The Euro scenario would be snow to sleet to rain (maybe freezing rain in the northwest hills?) while the GFS would be mainly snow. The Euro solution – with its ensemble support – is not a blockbuster snowstorm for Connecticut but it would be a royal pain for the day before Thanksgiving.
At the very least plan for an ugly day of travel on Wednesday.
Monday looks like an interesting day with a very sharp temperature contrast across the state and a little bit of everything weather-wise. Sleet, freezing rain, rain, thunderstorms, and gusty winds all a possibility depending on where you live.
Let’s start off with the winter weather threat. A bit of moisture moves in after midnight and temperatures near the ground will be close to 32 degrees in the Northwest Hills. We can’t rule out some sleet pellets statewide but any legit impact from wintry weather will be northwest of Hartford.
Here is a sounding valid tomorrow morning at 7 a.m. off the NAM model. Above the ground there’s a sharp increase in temperature but right near the surface the cold air hangs tough (the red line is temperature… the farther right the line gets the warmer the air… the higher up you go on the graph the higher the elevation above the ground). This is a freezing rain signature and it does appear that some light freezing rain is a possibility during the morning commute – especially in the Litchfield Hills. The setup isn’t great for a long-duration or serious event but in the hills of western Connecticut things could get a bit slippery tomorrow morning.
After that the focus will shift to winds. By afternoon, milder air will flood in from the south across the shoreline and eastern Connecticut. You can see the milder air in this map with a sharp temperature contrast from northwest to southeast. Also, you can see the cold air wedged and trapped in the valley! 41F at BDL and 59F in Hartford!!! Seems odd but it actually happens more often than you may think.
How cool! Literally cool if you’re in Springfield, Enfield, or Windsor Locks! Where temperatures warm up gusty winds could really be an issue late tomorrow afternoon into early evening. The GFS model shows 50 knots of wind at 600 feet above the surface at Groton tomorrow at 7 p.m.
While an inversion (temperatures increasing with height) will keep the strongest winds from mixing down this is too close for comfort. There is the potential for damaging winds in southeastern Connecticut tomorrow given how strong the winds just off the deck are AND the fact the inversion isn’t particularly strong (i.e. temperatures only increase a bit with height – the increase isn’t that dramatic). Isolated power outages and gusts over 45 m.p.h. are certainly possible east of New Haven along the shoreline tomorrow.
It won’t be a big storm by any means but we have some snow on the way. In general only minor accumulation is anticipated but, in the hill towns especially, up to 2 inches is possible which will make roads a bit slippery by morning.
The issue with this storm will be temperatures in the lowest 2,000 feet of the atmosphere. Here’s the GFS model for later this evening showing temperatures at 925mb or about 2,500 feet above sea level. The 0c line will drop south as freezing levels drop but it will take some time to transition the rain to snow (though above 1,000 feet in elevation the precipitation will likely begin as snow).
We’re not talking about a large amount of precipitation (liquid totals near 0.25″) and we will waste some of the precipitation as rain initially so final totals will be kept down a bit. If you’re feeling lazy tomorrow morning no reason to shovel the driveway as most of the snow will melt during the day tomorrow with highs near 40F!
Of all the computer model data I look at – model derived snowfall totals is either dead last or not looked at at all. They’re about as useful as a piece of garbage.
Take today’s 12z GFS run valid Monday morning. I’m sure this map will make the rounds soon from bad TV weather readers, weather hobbyists, and knowledgeable meteorologists who have sold out their credibility for page views, twitter followers, and/or Facebook likes.
Are you excited for the 7″ of snow in Willimantic??? Don’t get too excited yet! A look at the GFS model for Willimantic shows that during the height of the storm the freezing level is over 2,000 feet above ground and temperatures are as warm as 2.5C just above the surface. That would be some wet snow for the hills but it certainly wouldn’t be 7″ of snow for Willimantic or Norwich. More like 0″ for Norwich and Willimantic.
Don’t be fooled by computer generated maps with funky snow algorithms. I haven’t found one that is even remotely useful. Going back to basics with model soundings is the only way to accurately forecast events like this.
The Arctic blast is on schedule and continues to look quite impressive. The initial surge of coldest air this week will stay to our west though temperatures will drop in a big way here in Connecticut.
Our computer models absolutely nailed this big pattern shift – and for the last 10 days have wavered little. A very large block (-EPO) over Alaska and the Northwest Territories will dislodge a large chunk of cold and the pattern looks like it will remain quite stable. You can see even 9 days from now the lower 48 is dealing with an impressive cold shot with 850mb temperatures (just a few thousand feet up) between 10 and 20 celsius below normal!
Temperatures will go well below normal this weekend – but next week looks even colder after a brief reprieve from the chill on Monday. I said it last week and I’ll stick to my guns here that odds are better than 50/50 we’ll have to deal with a pre-Thanksgiving snow threat. While it’s by no means a certainty it’s certainly more than climatology (or the typical odds of a snow event this time of year).
Bundle up, enjoy the cold, eschew the silly polar vortex hype, and stay warm!