Overall the details around Debby’s impact have improved, she is expected to pass to our west, making her closest approach on Friday night.
The image above shows the low pressure passing over western New York. This more westerly tracked has also shifted the heaviest rain west of our region as well. For that reason all current flood watches are also focused outside of our region.
Timing: Rain associated with the strong southerly flow will continue to drive periods of showers and rain over the next 24 hours. Rain will continue to be inconsistent in its intensity and scattered in coverage. As we head into Friday afternoon we will need to monitor any thunderstorms that do develop as being on the eastern side of the circulation of Debby, combined with a strong southerly sheer will produces conditions favorable for rotation of thunderstorms that do develop, isolated tornadoes cannot be ruled out.
With that said, persistent cloud cover will cap daytime heating and for that reason CAPE remains low, so any thunderstorms that do develop may struggle to reach the ability to become supercell’s, nevertheless the threat remains worth mentioning.
The heaviest rains associated with Debby and the frontal boundary arrives Friday night, a squal line of low capped thunderstorms, gusty winds and heavy rain will push through the region from west to east between 2-7AM Saturday. This will likely be the most impactful weather we see from this system as it will contain the heaviest rainfall and strongest gusts that may mix down during the heaviest precipitation.
Here’s a look at the modeled wind gusts overnight Friday into Saturday, keep in mind that this occurs during the heaviest precip, history tells us that these winds translating to the surface will be limited. We should expect winds of 15-30 mph with higher gusts occurring during heaviest precip rates or thunderstorms. Can’t rule out a few gusts over 40 mph during this period.
In terms of rainfall, let’s take a look at the latest.
As mentioned above the axis of heaviest rainfall is west of the region, but the 1-3” of rainfall across our region mostly occurs Friday PM into Saturday. Just because flood watches aren’t in effect, does not mean that flash flooding can’t and won’t occur in parts of our region. It is more likely that any flash flooding that does occur will be isolated, tied to poor drainage, low lying and smaller streams.
Please continue to stay tuned as we will update frequently as the system nears the region.