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How Long Has It Been Since Hawaii Has Seen a Tornado Warning?

It has been 2,289 days since Hawaii has seen a tornado warning issued by the National Weather Service (NWS). The last tornado warning Hawaii saw came on December 13, 2008, and according to the Storm Prediction Center (SPC) there was a confirmed EF-0 tornado on Kauai Island near Pakala Villiage that day. Since then there have been tornadoes confirmed in Hawaii in 2009, 2011, and 2012. The NWS office in Eureka, CA has not issued a tornado warning in 4,480 days, which is a little over 12 years! The last confirmed tornado for the Eureka office according to SPC came on January 20, 1996, about 19 years ago!

Number of days since last tornado warning
Number of days since last tornado warning

So why has Hawaii not seen any tornado warnings since 2008 but have 3 confirmed tornadoes since? Why were there warnings issued in California even though they have not seen a tornado since 1996? Is there something wrong with the way warnings are issued? Prior to the Super-outbreak in April of 1974, tornado warnings were typically only issued after the tornado was already confirmed. Today’s tornado warnings, on average, can be issued up to 15 minutes before the tornado event. Only one out of four tornado warnings issued today carry with them a confirmed tornado, that being said, each tornado warning issued by the NWS should be taken seriously.

The success rate of having a confirmed tornado within the area of a tornado warned area is on average around 70 percent, a number that has more than doubled since the 1980’s. This also means that 30 percent of tornadoes happen with no warning attached to them. In July of 2014 when an EF-1 tornado touched down in Kent County, Michigan, there was no tornado warning issued with this storm. NWS in Grand Rapids reported that the tornado popped up suddenly and without any warning signs on the radar, which happens to scan every four minutes. By the next scan the storm was already beginning to weaken and it was decided that a severe thunderstorm warning would be issued instead.

Tornadoes can be embedded in squall lines and may form so quickly that they don’t show a signature on the radar sweeps, while others could be visually hard to see due to the time of day or amount of precipitation wrapping around them. These types of tornadoes may not be associated with a tornado warning and later confirmed by the NWS survey team as being a tornado. Some storms show strong rotation signatures on radar indicating that a tornado could be present but not confirmed and a tornado warning will be issued. This is why only one in four tornado warnings have an actual confirmed tornado- it is better to get the warning out if there is any hint of a tornado than to not issue one. Whatever the case may be, it is important to make sure you heed all warning and watches issued in your area not matter what.

Severe weather season is upon us, and with a severe weather threat this coming week, stay tuned to WeatherNationTV for any updates on severe weather.

Brandon Thorne – WeatherNation
Photo credit: Iowa Environmental Mesonet

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