No warnings, no sirens for Portland tornado
PORTLAND, Mich. — The National Weather Service states an EF-1 tornado with 110 mph winds ripped a path of destruction a few miles long through Portland on Monday afternoon. That’s almost an EF-2! 111 mph winds would be categorized as EF-2, so it was certainly on the maximum end of the EF-1 scale! The width was 50 to 100 yards and the approximate length was four miles, although it skipped in several areas along that path. Imagine the width of a football field at times! The path originally started about 3.5 miles north and west of the city. Both the NWS and city officials say the tornado hit Portland about 2:30 p.m.
An NWS survey revealed that there was damage to homes and businesses throughout the Portland area. More than 70 structures were impacted with roof damage or broken glass, including four churches. Hundreds of trees were damaged with many uprooted or snapped trunks.
There was no severe weather warning and no sirens activated. Why? As some may recall, this situation was similar to the brief tornado that touched down in early July 2014 in Kentwood, Mich., where there was damage but no tornado warning was in effect at the time.
“Here in Michigan, we typically have these quick spin up tornadoes that last less than 10 minutes that are on a radar scan, if at all,” said NWS warning coordination meteorologist Jim Maczko. “This was one of those cases where it spun up so quickly and disappeared so quickly that it was virtually undetectable ahead of time by radar.”
Smaller and weaker tornadoes like these “tend to do a lot of damage but don’t necessarily destroy homes like we see in Oklahoma and Alabama,” said Maczko. “Those are the types we get a lot of here in Michigan, and unfortunately those are the most impossible to predict ahead of time.”
While radar technology has come a long way, especially in the last few years, it still cannot detect everything. Volume scans on Doppler radar take three to five minutes. By the time the signature shows up and the warning can be issued, the tornado has already spun up, done damage, and is gone! In severe weather mode a quick scan can be completed in about two to three minutes, but by the time two complete scans are seen and the warning issued, these brief spin up tornadoes have touched down and have already lifted.
There has been recent criticism by the some in the general public that the weather service has missed these small tornadoes by failing to issue warnings ahead of time. In a perfect world we’d have a warning in place with adequate lead time for every storm that hit. What people fail to realize is the NWS Doppler radar is located at the G.R. Ford International Airport in Kent County. On the lowest elevation setting at .5 degrees, the radar beam is already at an altitude of about 2,500 feet by the time it reaches Portland in eastern Ionia County. Since the earth is round, the beam shoots out from the radar in a straight line…it does not follow the curvature of the surface/earth. That means the tornado with our current technology would have been missed and couldn’t be seen effectively since it would have literally been BELOW the radar beam. Some slightly higher rotation weakly showed up where the beam intersected the upper level of the tornado, but to warn for something that brief with one radar scan that wasn’t clearly defined is not the policy of the weather service.
What meteorologists like to see and what makes it easier to detect is the circulation of a mesocyclone in mid-levels of a storm. More well defined longer lasting tornadoes typically will have an associated mesocyclone (or parent spin of the storm) that can be tracked on radar at a few different levels, giving meteorologists advance warning or lead time to identify the radar signature and issue the warning. Again, these brief spin up tornadoes typically lack such a feature (or at least a well defined one) and are far more difficult to identify on radar if it can be done at all. Until our current WSR-88D radars can follow the curvature of the earth via the beam, this will likely continue to happen. In fact, WSR stands for weather survellience radar and is actually 1988 technology. The radar itself has undergone several updates over the years, but the root technology is almost 30 years old. Imagine the cost of switching out all of these federal owned radar systems across the entire country?
We should also note that it is not the responsibility of the National Weather Service to activate warning sirens. Generally, that task is done by local and county officials at their discretion. All activate for tornado warnings, and some even activate sirens for damaging straight line winds at certain thresholds.
Also noteworthy is that NWS is trying to get away from issuing tornado warnings for every brief tornado or spin up that occurs (mainly EF 0 and EF 1). They prefer to issue a SEVERE THUNDERSTORM WARNING with a text line stating that a tornado is possible. If they have defined rotation for at least two radar scans, or confirmation by a weather spotter of something on the ground, then a TORNADO WARNING will be issued.
In the Portland case, the tornado hit about 2:30 p.m. and the SEVERE THUNDERSTORM WARNING (with tornado text) wasn’t issued until 2:41 p.m. Weak rotation on radar and the brief spin up was simply too quick for the current technology to catch.
To some degree, folks heeded the severe weather threat FOX 17 conveyed in the days leading up to the storms.
There were no injuries or deaths, and emergency county managers and several other local organizations worked well together to handle the calamity, according to several reports we received. You can read the NWS damage survey here.