GRAND RAPIDS, Mich. (WOOD) — Whether you are thinking about the early 2000s, or as far back as the 1970s, it definitely seems there have been fewer Tornado Watches issued each year for West Michigan.
So, why is that? After digging through some data I have three possible reasons why it may feel like we never seem to see a Tornado Watch anymore.
Before we get started, let’s just review two terms. A “Watch” means all the ingredients are in place for a tornado to occur later that day. A “Warning” means a storm is currently producing, or could momentarily produce a tornado. Here’s a fun way to remember the two, made famous by Meteorologist Brad Panovich.
These three factors have likely contributed to the drop off in Watches in recent years:
WE ARE IN A SEVERE WEATHER LULL
It is no secret we have seen drastically few severe weather reports in Michigan lately, let alone tornadoes or tornado warnings. Last year, there wasn’t a single tornado reported in lower Michigan and only one in the Upper Peninsula. Our state usually averages 16.
It has been 617 days since a Tornado Warning has been issued in Michigan, and even longer since a Tornado Watch has been issued. Why is the count lower for Tornado Warnings than Watches? Well, a tornado spun up on a day that usually doesn’t produce widespread tornadoes 617 days ago, triggering a warning.
Watches are issued on days when a tornado seems fairly favorable. They are issued nationwide by experts that work at the Storm Prediction Center in Norman, Oklahoma.
Along with that, there have been incredibly few strong tornadoes in our state in the last several decades.
So one of the reasons you’ve seen fewer Tornado Watches issued is purely because we haven’t had as many days where we needed one.
TECHNOLOGY HAS IMPROVED FALSE ALARM RATES DRAMATICALLY
Another key reason for a drop in watches is more accurate forecasting. Technology has improved drastically in the last several decades, and even the last several years. Research has also compounded. These advancements mean forecasters are getting much better at pin pointing days when tornadoes may form, and identifying which storms are most likely to drop a tornado.
This is a fantastic advancement. False alarm rates were very high in the past. Out of caution, and using the best technology at the time, meteorologists would issue a Tornado Warning for any storm that exhibited tornadic rotation.
This graphic is astounding. It shows a comparison of the square footage tornadoes actually touched down between 2008-2012 in yellow, versus the total square footage warned for tornadoes during that same time frame. It shows how much higher the warning area is compared to the impacted area.
Unfortunately (or fortunately) many of those storms never produced a tornado. This led to the public taking tornado warnings less seriously.
Fortunately, advancements very recently have led to better forecasting and issuance. This graph shows the number of warnings vs actual tornadoes by year. Notice the big drop in 2011. This is likely after the implementation of research that helped to identify debris signatures, and verify tornadoes on the ground using just a radar.
THE TORNADOES WE’VE BEEN SEEING LATELY ARE WEIRD
The classic supercell tornadoes that litter YouTube and social media feeds have been few and far between for us in Michigan. Lately the tornadoes that have been able to spawn have been mostly quick, short-lived and triggered on very low-risk days.
Because these storm and tornado days of recent years have been so low risk, the expert severe weather forecasters that issue Tornado Watches for us here didn’t even issue Watches on those tornado days.
This graph shows how few Tornado Watches we’ve seen in the last few years.
Notice, despite the fact a Watch wasn’t issued, there were still tornadoes in years like 2014, 2016, and 2017.
What this shows us is that the types of tornadoes we have been seeing are quick, low impact (as far as tornadoes go) and almost impossible to warn. By the time a radar scan begins to show rotation in an anything-but-classic storm, the tornado has touched down and lifted and left, leaving forecasters no choice but to issue a fast warning, or none at all.