As you get ready for the week ahead, keep in the back of your mind that the weather may sometimes be a little bit of a trouble once in awhile…
The first "trouble" may start after midnight tonight in the form of scattered snow showers. Most of the night will be snow-free, just simply increasingly cloudy and colder, with temperatures going down into the 20s. Scattered snow showers are most likely to arrive after 4 AM. As I write, they are drifting across southern Ontario, moving southeasterly in a "southern New England trajectory," following the jet stream wind flow out ahead of a developing warm front. As this snow-making disturbance marches through Connecticut tomorrow morning, it will continue to bring scattered snow showers that will likely last until about noon. The ground and air will be cold enough to support accumulation of any snow that falls. Most of us should expect a coating at most; a few of us may see in upwards of an inch of accumulation, particularly in the higher elevations of the hills northeast and northwest of Hartford. And, there will be some towns that hardly receive a flake of snow, due to the scattered nature of the showers. Nonetheless, there will be areas of the state that see enough accumulation that roads may get skimmed with a slushy coating of snow. The later in the morning you commute, the more likely you will be affected by the snow.
Clouds will be persistent tomorrow afternoon after the snow. The models depict an atmosphere that will have enough moisture to make the afternoon sky more cloudy than sunny, but despite the predominance of clouds, peek-a-boo sunshine will help highs reach into the lower-40s during the afternoon, which will melt any minor accumulations away fairly swiftly.
There may be a flurry or two, especially in northeastern Connecticut, Monday night. The warm front that brought us the morning snow still will not have completely cleared and another wave of low pressure will be moving southeast ahead of it, moving from Ontario and Quebec into eastern New England. Although we'll be clear from 99.9% of its effect, we still cannot rule out a few flurries skirting by the Quiet Corner. Otherwise, under mainly cloudy skies, lows will be in the 20s.
Tuesday will be the nicest day of the week – though far from perfect. High pressure will be trying to build into the state and draw in milder air. It will be relatively weak, which will mean that, instead of perfectly sunny skies, there will be a lot of higher level cloudiness drifting over the sky. Still, we will have a shot at seeing 50° in at least parts of the state, especially if there is adequate sunshine come through the high cloudiness.
Wednesday and Thursday pose the biggest weather hurdle of the week. As early as Tuesday night, clouds will be building over our sky as a developing area of low pressure strengthens over the Ohio Valley. It will be working with the good ole standbys: cold air and a strong northern jet merging with a moisture-laden southern jet. By noon on Wednesday, the storm will be entering New England with precipitation.
Precipitation type during the first half of the storm will be a huge forecasting challenge with this storm because it is not clear how well cold air will be able to drain back down into Connecticut from the north, after having enjoyed a mild Tuesday. The models generally say that this cold air will have limited success, reaching northern and western Connecticut only. This scenario would mean that most of the state would see rain developing Wednesday afternoon in 40 degree air. Only the Litchfield Hills might see a start as an icy mix before a transition to rain by later afternoon. Having written this, it is equally plausible (and more usual) to have the cold air amply established and resistant to move, giving most of the state several house of sleet or freezing rain before changing to plain rain. Regardless of whether we have an icy start or not, all models say that the whole column will be above freezing and making rain late afternoon through about midnight before sub-freezing, snow-making air filters into the state from the northwest. The models indicate there will be sufficient "wrap around" moisture on the western half of the storm to support several hours of light snow after midnight into Thursday morning. Should that aspect of the storm forecast ring true, Thursday morning would be snowy, with a slushy base of snow getting covered over with a more powdery snow by the time morning rush is here.
There are far too many missing pieces to make any attempt at accumulation estimations; such deliberation is an exercise in futility at this point. Early model projections point to Connecticut possibly getting an inch of liquid equivalent, but that is highly suspect on its own right, due to the fact that the parent circulation is still out over the Pacific and its data have not been sampled. And, even if that number is a sound estimate, we don't yet have a comfortable handle on the precipitation type yet. We're still about 36 hours away from being able to make a sound accumulation forecast.
Once the storm departs -- regardless if we get a direct effect or what that effect will be – colder air will come behind, offering highs in the low-30s and lows in the teens and single digits Thursday. It will also be windy in the wake of the storm, making Thursday aggravatingly cold for a March day. Weak high pressure will build into the region in southern New England as a weak low pressure system moves across northern New England. The end result will be filtered sunshine and a lot of clouds, the chance for isolated flurries or sprinkles and moderating temperatures: upper-30s Friday and 40s Saturday and Sunday.
Have a great week!
Meteorologist Mike Cameron