Friday-Saturday’s severe weather threat: what needs to come together

Weather Blog

ROCHESTER, N.Y. (WROC) — When it comes to severe weather it’s important that all the ingredients come together in just the right way. In Friday to Saturday’s threat for severe storms, there are many ingredients present that do support the chance for a few thunderstorms, and perhaps even a stronger storm to pop. Although, if the timing of the fronts at play don’t arrive at just the right time, then it will be a no-go with only a few thundery downpours to worry about.

Think about it like this: If you were to bake a cake without eggs, or flour it would come out of the oven and fall apart, right? The same concept applies to weather. You may have all but just one ingredient, and the outcome won’t be quite the same without it.

For a thunderstorm you need 3 key ingredients: a lifting mechanism, instability, and moisture. A lifting mechanism can come in the form of a warm or cold front, and instability is another term for energy, or “fuel” for storms.

In order to get a severe thunderstorm, you need all 3 of these plus one more ingredient known as shear. This is the amount of spin present in the atmosphere described by the changing of the winds with speed and/or height.

Here’s the current severe threat being advertised for late Friday into early Saturday morning:

Let’s talk about what we have to work with, and how the threat is low, but not entirely zero.

Friday Discussion:

On Friday morning through early afternoon, a mid-level disturbance will push through the region bringing increased cloud cover and a cluster of shower activity our way. The timing of these showers with the increased cloud cover produce a strong likelihood of limiting the amount of energy and warmth needed to fuel storms. It’s likely we see merely a few passing showers, more on the scattered side of things Friday afternoon with just a bit more cloud cover around.

By Friday evening and overnight the region will start to be engulfed within the warm sector of a warm front, bringing in an extra surge of warmth and moisture. This is the time frame we’re starting to pay attention to. This paired with the decent amount of shear present could be just enough out ahead of the cold frontal passage Saturday for a low end threat for isolated storms producing damaging winds, or even in a very rare occurrence a tornado warning to be issued. The most favorable environment for these conditions continues to be well south and west of the Rochester area.

Saturday Discussion:

Our attention then turns to Saturday as we await the passage of a cold front. The timing of this front will also determine whether we get a few showers and storms Saturday morning, or if the front waits until the afternoon to push through, and we could get a lake breeze boundary to assist in popping up a storm or two. The amount of convective available potential energy (CAPE), or storm fuel present look to increase to sufficient enough levels by the morning and afternoon, but we’ll need that front to push through at just the right time in order for any storms to get going. At this point the threat of anything severe still remains on the lower end of the spectrum, but it’s a game of ups and downs. Everything could end up coming together in just the right way for a severe storm Saturday afternoon. This would feature the threat for strong wind gusts, heavy downpours and even some hail. Stay tuned as more detailed model data comes filtering in.

All in all, the greatest risk for any severe weather overall remains across portions of extreme southwest New York, but that doesn’t mean the Rochester area has a zero chance of seeing a thunderstorm go “rogue.”

Make sure you’re keeping up to date with the latest weather information, and you can check our local forecast with updates on the forecast HERE.

~Meteorologist Christine Gregory

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