I get this question ALL the time, why do storms appear to break up when they hit Lima?You may be surprised to know that this phenomena has nothing to do with industry here. Instead, it might just be because we can’t see it!
A very nice graphic posted by the National Weather Service Wilmington Branch today is a GREAT explainer how radar beams function. Here is the graphic that shows how the radar image can drastically chance based on how far a storm is from the radar site.
Distance from radar sites is something that REALLY affects us here in West Central Ohio everyday. As the radar beam shoots out from the Doppler Radar site it spreads out because of the curvature of the earth (see picture above) so the beam can hopefully scan a potential storm from top to bottom. But what happens when a storm is almost 100 miles away from a radar site? Unfortunately the radar beam misses part of the storm, in our case here in Lima that means that roughly the bottom nine to ten thousand feet of a storm can’t be seen! That’s basically from the surface up to 2 miles in the sky that is missed by radar here in Lima.
Here is a look at NWS Doppler Radar sites covering West Central Ohio and their distances from Lima.
Because of this distance, storms could appear as if they are breaking up at times over this area but could actually still be there, they just can’t be picked up on radar! The good thing about this is that in MOST cases, severe thunderstorms are easily over 30 or 40 thousand feet tall in the sky! Storms of this magnitude are easily seen on radar, even over 100 miles away. Many of these severe storms can produce strong mesocyclones that are easily picked up on radar as well which can be a precursor to a funnel cloud or even a tornado. In the case where there is strong rotation throughout a thunderstorm from nine to ten thousand feet and above, a tornado warning could likely be issued based on the assumption that even though radar can’t see much below 9 thousand feet, there is a very good possibility that rotation extends close to the surface even though that can’t be seen on radar. On the contrary, there are times when the rotation is strictly in low levels less than 2 miles from the surface. A good example of this was just a few weeks ago when several outflow boundaries interacted with each other creating some low-level spin that spun up a brief “Gustnado” in SW Putnam county. Radar sites covering West Central Ohio would never pick this up in their scans, it’s just too low to the ground.
So what can be done to remedy this?
Unfortunately not much for now. Doppler Radars are expensive, VERY expensive! There are some TV stations across the country that actually have their own radar sites, but they are few and far between and even then they are not NEARLY as powerful as the radar sites that the NWS maintains.
For the NWS meteorologists warning storms in this area, this is no easy task. And in my opinion they have quite the challenge in doing so but do it very well!
Just thought I would share this little tid bit with you all! Hope you find it as interesting as I do.