"Weather Bomb"

Are you ready for the weather bomb? That's a term you've likely heard a lot today as a very powerful storm approaches. So...what the heck is a "weather bomb?" A weather bomb is the meteorological term that describes a rapid drop in pressure over a 24 hour period. Meteorologists measure pressure in millibars and for a storm to be considered a weather bomb a region would need to experience a 24mb drop in pressure over 24 hours (or 1mb/hr). So is this storm a "weather bomb?"

To determine in advance if our region will experience such a rapid drop in pressure we need to look at both the leading edge of the storm and the "central pressure" (or the area of lowest pressure). Since these storms generally move from west to east we'll look at the eastern edge of the storm compared to the center. (I grabbed the image above from a forecast model so this is not an actual observation...but it's pretty close to reality). Just ahead of the cold front the the pressure is around 1000mb compared to a central pressure of 956mb. That's a 44mb drop! While I'm not expecting to see a 44mb drop in pressure in 24 hours, considering just how low the central pressure of this storm is, a 24mb over 24 hours is very likely. So what does this all mean for Peterborough and the Kawarthas? The faster the pressure drops the faster the winds will be. This is a called a pressure gradient. When you go from an area of high pressure to an area of low pressure over very short distance you have what is called a "steep pressure gradient." The steeper the gradient...the faster the wind. Tonight we'll see a very steep gradient leading to sustained winds in excess of 40km/h and gusts in excess of 60 to 80 km/h. High winds with heavy rain and possible thundershowers can be expected this evening all thanks to what is know as a "weather bomb." While we're not talking about a hurricane here...tonight will still be very windy with the potential to be fairly active.