Saying the upcoming storm is going to be a mess doesn't do it justice. The storms we have dealt with this winter have been predominately easy in the precipitation-type department. This time, however, is not going to be the case. Despite Connecticut being such a small state, the differences in weather may vary significantly within the state. This adds immense challenges to the forecasting process and to the communication aspect of this storm.
Before we get into our weather in Connecticut, let's take a moment to appreciate (meteorologically) what is transpiring across the majority of the country. Record-breaking Arctic cold (and prolonged cold) plunges well into the deep South with multiple winter storms impacting areas which aren't accustomed to winter weather. Why is this happening? We'll take a brief look below (well if you read my posts, you know I'm usually never brief with these things).
For the better part of the past few weeks a piece of the polar vortex has been displaced south and has become positioned in the vicinity of the United States/Canadian border. With the polar vortex being displaced from the Polar region, strong ridging has built into the Arctic and polar regions. Meanwhile, ridging has become established across the North Pacific. This is the perfect recipe for Arctic air outbreaks to sag south into the United States:
Flash forwarding to Monday morning (February 15) the jet stream will be digging extremely far south...pretty much into Mexico! With the jet stream displaced this far south combined with the configuration shown above, this is prime for Arctic air all the way into southern Texas:
At the surface, a very strong and robust high pressure (with central pressure greater than 1040mb!) is positioned across the upper-Midwest associated with the polar vortex lube. This is just funneling low-level Arctic cold into the majority of the country:
What does all of this have to do with our potential weather here in Connecticut? Well, quite a bit actually. There is something else I would like to illustrate and I am going to use forecast temperatures at 850mb (roughly 5,000 feet above the ground) for Monday morning. Off the Southeast coast of the United States is a large ridge (known as the Southeast ridge). The colors here can be correlated to warmer temperatures and colder temperatures. The brighter colors represent warmer temperatures while the darker colors represent colder temperatures. I've outlined in red the "battle" ground between Arctic cold and more tropical warmth with an orange arrow directed towards Connecticut. We are going to be in this "battle" ground between Arctic air and more tropical air. This is what is going to result in a slew of precipitation types across the state Tuesday:
By Monday evening, low pressure moves northeast up along the Eastern Seaboard and approaches Connecticut. Initially, temperatures at the surface will be below-freezing as winds out of the northeast (or east-north east) will funnel in low-level cold thanks to that extensive high pressure which stretches through eastern Canada:
However, as the low pressure system continues to organize, we'll see temperatures between 3,000 feet and 7,000 feet above the ground actually warm above-freezing. This is due to low pressure up around 5,000 feet developing well to our west:
What can we expect? Well what we won't see much of is snow. In fact, outside of maybe the Northwest hills I don't think anyone sees any snow so this can be ruled out. The bigger challenges arise with sleet and freezing rain potential. In terms of sleet and freezing rain potential this will be determined by;
1. EXACT track of the surface low pressure. The closer to Connecticut this tracks and the earlier this strengthens, the greater the likelihood for warmer air to move in at the surface. This scenario would present more of a mix to rain for a greater portion of the state. Should this track not so close to Connecticut, there is greater potential to keep colder air locked in at the surface, resulting in higher likelihood for sleet and freezing rain.
2. The configuration of the thermal profile (how temperatures are changing as you ascend through the atmosphere). This will be easier to explain with a visual, but the structure of the thermals will be a determent in sleet versus freezing rain.
At this juncture, the potential exists for a quite a bit of sleet and freezing rain across the state (away from the immediate shoreline) with even the potential for significant icing (> 0.50'' icing) which would bring about power outages. All of these details are extremely complex and there is a quite a bit to resolve moving through Sunday. Below, is what we could be facing:
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