Colorado sets a new big hail record
Aug. 15, 2019:
Reed Timmer said Tuesday morning that Colorado might set a new state hail record, and they did! The NWS in Goodland, Kansas, and the Colorado State climatologists have measured a hailstone at 4.83 inches in diameter, beating the previous state records, which were all estimated at 4.5 inches. The hailstone was likely over 5 inches when it fell, based on photos, but it may take a while for the final report to be issued.
Below are photos, taken Wednesday by the NWS, of the hailstone, which had been frozen since 30 minutes after it fell Tuesday evening near Bethune, Colorado.
I wanted to blog about this because there has been some confusion on the topic.
SUNDAY IN OTIS: A lot of local media rain stories Sunday (Aug. 11) about a possible record hailstone in Otis, Colorado, which was measured at 4.5 inches that afternoon, tying the record. That storm had hail on radar over 2.95 inches on the MRMS six-hour hail track image, right over Otis, and the Denver NEXRAD SCIT product showed 3.18 inches a little earlier to the southwest. Could it have been 4.5 inches in Otis? Sure. Radar isn't perfect. Even though the report isn't exactly the right place at exactly the right time, spotter reports sometimes aren't.
BACK TO BETHUNE:
The Bethune report was a little further off from where the large hail was -- almost 10 miles, and the largest hail in Bethune on the MRMS six-hour hail track image was only 1.18 inches -- at best. This made me immediately suspicious, but again, spotter reports aren't always quite in the right place, and the Goodland NEXRAD SCIT showed hail of 3.97 inches to the southwest. Could it have been as big as 5 inches? Sure.
My quotes from our story are shown below, along with AccuWeather radar images from the Goodland KS NEXRAD (Reflectivity and 1-Hour Hail Swath).
"AccuWeather meteorologist and social media manager Jesse Ferrell explains forecasters analyze specialized radar and must know what tell-tale signs to look for.
"NEXRAD Doppler Radar detects the size of water droplets that its beam intercepts, so higher 'reflectivities' (colors you see on your average television or internet radar) indicate larger drops, or hail," Ferrell said. The radar snapshot seen below shows the highest reflectivities (purple) southwest of Bethune at the time of the hail depicted in the photo fell on Tuesday.
NEXRAD Doppler Radar detects the size of water droplets that its beam intercepts, so higher "reflectivities" (colors you see on your average television or internet radar) indicate larger drops, or hail.
IMAGE CAPTION: Baron Doppler Radar detects the size of water droplets that its beam intercepts, so higher "reflectivities" (colors seen on the average television or internet radar) indicate larger drops, or hail.
Meteorologists also have access to special radar products that attempt to gauge the size of hailstones, Ferrell added. The Baron Hail Track image, which estimates sizes of all the hail that fell in the area for one hour and is depicted above, shows extreme hail southwest of Bethume on Tuesday afternoon. Another tool that meteorologists use, the NEXRAD radar's Storm Cell Identification Tracking, helps estimate the size of hailstones. Radar images showed a maximum estimated hail size of 4 inches in diameter at time of Tuesday's storm. Meteorologists look at the darkest part of the hail imagery to gauge the intensity, depicted in purple in the radar reading, as shown in the screenshot below.
Could the hail indicated there have been what's shown in the photo?
IMAGE CAPTION: Meteorologists use the Baron Hail Track image to estimate the size of hailstones. This image shows a maximum estimated hail intensity at the time the hailstones fell, in the spot where the red arrow is pointing.
"It's plausible," Ferrell said, adding, "the radar's beam can hit only a limited area of the storm's vertical structure." The National Weather Service in Goodland, Kansas, and the Colorado State climatologist [are] investigating will issue the final determination on whether the hailstone seen in the photo is real, and whether or not it breaks the Colorado state record of 4.5 inches, which, incidentally, was just tied Sunday."
