Many people have had the experience of a large storm seemingly heading right toward them, only to end up with just a gust of cooling wind or a few drops or no rain at all. Year after year it seems to happen periodically each summer. It happens to me routinely.
So this leads people to believe there is something special about their town or neighborhood that “causes” this.
Some sort of magic effect or “bubble” or forcefield that deflects storms. Shields up Spock!
It’s the river! It’s because I am in a valley! It’s because I am downtown in a big city! It’s because I am in the suburbs! It’s because I live way out in the country! It’s because our area is flat! It’s because I live near or in the mountains! It’s because of the Lake! It’s because I don’t live near the lake! It’s the old Indian burial grounds! (It’s because of everything even if they are opposites).
Informal polls have shown 97% of people believe there’s something special about where they live that makes the weather behave in a unique way for thunderstorms. A “protective bubble”.
But if almost everyone experiences the same thing, logically that alone should tell you that there is nothing special about your experience or perception or where you live.
Notice the importance of the words seems and believe in the sentences above. Perception is not the same as reality.
If it happens to everyone then no one is ever getting a storm and we know that’s not true.
So riddle me why weatherman...
There are two basic types of weather, synoptic (wide-scale) and sub-synoptic meso/micro (small-scale).
In the cooler seasons we get mostly synoptic systems that cover multiple states with rain, thunderstorms or snow/ice at the same time so pretty much everyone uniformly is impacted. So no mysterious invisible bubble of protection.
However, in the warmer seasons we get the sub-synoptic small scale weather. An individual thunderstorm can be less than a mile across. It has to start and end somewhere which is why you can drive in and out of it or even walk with one side of the street raining and the other dry.
Garden variety “air mass thunderstorms” in the summer form, move and decay at random in the chaos of the atmosphere. They pop-up, intensify, then dissipate. Then the cool air they cause becomes the trigger for a new storm near-by. Rinse and repeat.
So when it seems storms are splitting or going around you, in reality it just fell apart before it got to you or just as it reached you. Then a new one formed beyond you giving the impression you have a protective bubble over your neighborhood.
What you may not realize is when YOU do get hit by a good storm, guess what? People only a few miles from you are watching it expecting it to hit them but it falls apart before reaching THEM.
In other words this is common and normal weather behavior.
Over the long term storms miss or hit you just as often as they hit or miss any other town in Metro Atlanta.
This is why forecasting the odds and coverage of this type of thunderstorm days or even a day in advance is frustratingly difficult to almost impossible!
This type thunderstorm forecast can realistically only be predicted 2-4 hours in advance. 24-hours or beyond they can only be estimated.
This is why when it comes to standard “pop-up thunderstorms” we can start a day early morning expecting a 20-30% chance and end up 50-80%, or start out forecasting 60% and end up only 20% at the end of the day.
The reason is the factors that influence air mass thunderstorm chances and coverage are sub-synoptic and therefore often fall in-between the weather net going undetected.
This is why there is no such thing as hour by hour forecasts on an APP on a web site or anywhere else for this type of thunderstorm. No such thing as neighborhood or backyard weather forecasts. That’s just sales and marketing. We can sometimes do this but only with large synoptic weather systems.
The best that can be done for THIS TYPE thunderstorm is to give a best estimate of the time frame window where a storm is more probable, and maybe a sub timeframe within that when peak coverage is most likely.
I do this every morning on Atlanta’s Morning News hosted by Scott Slade on 95.5 WSB Atlanta’s News and Talk.
RADAR EXAMPLE FROM WEDNESDAY JULY 31 (SNAPSHOTS AT 5 MINUTE INTERVALS):
CONSIDER... White, Cartersville, Kingston, Jasper, Nelson, Kennesaw.
Jump ahead an hour from the last image:
Author Dennis Mersereau describes the amoeba-like nature of our hit or miss thunderstorm summer pattern:
Note comic strip at start of blog from xkcd.com.
For more follow me on Twitter @MellishMeterWSB.