Significant Severe Weather Threat Sunday

Today’s violent thunderstorm north of Hartford may only be the beginning of what could be a volatile weekend.

Looking at our 2 major computer model forecasts for tomorrow the severe weather potential is about as great as you’ll ever see in Connecticut. Both show exceptionally strong shear, a very strong triggering mechanism/lift, good instability, and extreme low level direction shear. Even though everything looks good on paper, and would indicate a tornado outbreak, there’s a lot that can go wrong.

Here’s a look at the forecast soundings and hodographs from the GFS and NAM tomorrow at Windsor Locks.
On the left of the sounding are the forecast hodographs. It’s a bit confusing but basically a strongly curved and long hodograph (yellow) indicates the potential for tornadoes, in this case strong tornadoes.

With extreme 0-6km bulk shear of 50 knots supercells are likely. Based on the hodographs above supercells maybe be able to produce strong tornadoes. But it’s not that easy.

We also will need strong instability to produce supercells and tornadic thunderstorms and it’s not clear that will be present. There’s a reason strong tornadoes are so rare in Connecticut and part of the reason is our proximity to the water. The cool water can make it tough to generate enough instability for tornadoes (especially with a southerly wind… right off the sound!). In addition, a wind profile like this can promote a lot of clouds and showers thanks to moisture coming in off the ocean and strong “lift” in the atmosphere.

If we are able to see enough sunshine and get the atmosphere to destabilize then tomorrow could be an exceptionally active severe weather day – like you would see in Oklahoma! Being able to generate that instability, however, may be a challenge.

Even though the threat for strong storms tomorrow is conditional on seeing enough sunshine I’m categorizing the threat as “significant” because of the “off-the-charts” parameters we’re seeing at the moment. If it seems clear the atmosphere will destabilize quite a bit tomorrow I’ll upgrade from “significant” to “extreme”.

Stay tuned tomorrow!!!

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