On Sunday, I mentioned watching Wednesday for our next chance of rain and thunderstorms as a front moved toward the region. As we've gotten closer to Wednesday, the signals for potential severe weather, especially in western and northern CT have grown. This is a special discussion to outline the potential tomorrow.
Overall Setup
First, let's be clear. It's still a bit early for widespread severe weather here in CT. As the graphic shows, the highest potential for severe weather will be in NW CT and far northern CT, where the best ingredients are likely to be. Severe weather is by its very nature mesoscale, meaning most see non-severe weather, and isolated to scattered spots do. We are not looking at a widespread severe weather threat here.
Now to the forecast. For severe weather to take place, you usually need four ingredients: Shear, Lift, Instability, and Moisture. Tomorrow looks hot and humid, especially inland with highs in the upper 80s to low 90s and dew points in the 60s. This will provide us with the first two ingredients for thunderstorms, by the way of instability and moisture.
While shear tomorrow looks marginal, it looks to be sufficient to provide for storm organization in New England and we will see lift in the form of an approaching cold front/shortwave.
The high resolution NAM below shows the possibility of thunderstorms tomorrow between 2pm and midnight. Don't take this projection to the bank, as things are certain to change in storm progression. What's important here is that the NAM shows isolated (discrete) thunderstorms nearby which may be able to maximize potential in NW CT followed by a broken line of storms that fizzle later in the day and evening.
The best severe weather potential currently looks to be in Upstate New York and northern New England.
Tomorrow morning and early afternoon look fine. That will allow instability to build and for some isolated to scattered thunderstorms to develop quickly during the mid-afternoon hours. For now, I think any storms will develop in the Berkshires or eastern NY between 1-2pm and slowly move toward NW CT. I expect showers and storms between 2-10pm, but this timing will be refined tomorrow.
Impacts
Again, for most this isn't likely to be anything other than garden variety showers or storms, but I'm doing a discussion because given the ingredients there is a chance (especially in NW CT) of storms with damaging wind gusts and a small tornado threat.
For that part of CT, the SPC has a 15% damaging wind probability in addition to a 5% tornado probability right along the border with MA and NY. Tomorrow is a day to keep an eye to the sky in NW CT.
Below are the MLCAPE (right) and Supercell Composite (left) projections from the high resolution NAM tomorrow afternoon. This actually looks pretty robust, but we will see what conditions look like tomorrow. Any storms that do develop in this environment could become strong to severe. Note that the most favorable conditions for storms are in northern New England and NW/far northern CT.
We'll be here with updates as conditions warrant.
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Thank you for reading.
-DB