JACKSON, Wyo. — On Thursday, Jan. 11, Jacksonites braced themselves for severe weather after the National Weather Service (NWS) issued a blizzard warning for the area. Although the blizzard warning was later downgraded to a more standard winter storm warning, this sparked conversation about the infrequency of blizzard warnings in the area, despite famously snowy winters.
After a tip-off from Teton County Emergency Management, Buckrail confirmed in the National Oceanic and Atmospheric Administration’s (NOAA) Storm Events Database that the last blizzard conditions recorded in Jackson fell on March 15, 1996. This appears to be Jackson’s only blizzard in NOAA’s records, which date back to 1950.
“It’s very hard to get blizzard conditions in mountain valleys,” NWS Riverton Warning Coordination Meteorologist Lance VandenBoogart told Buckrail. “Jackson Hole is a fairly large valley, but even still, it’s not connected to the larger air masses sliding down from Canada over the Great Plains. There are enough mountains around that slow that air down.”
To qualify as a blizzard by NWS standards, the storm must include sustained winds or frequent gusts in excess of 35 mph as well as visibility of a quarter of a mile or less, all sustained for three hours or more. In Jackson, wind speeds on the valley floor, reduced by the Tetons and other surrounding ranges, tend to prevent storms from hitting these particular benchmarks.
“The wind and visibility are really closely tied,” he said. “Jackson gets all sorts of heavy snow, but it’s when you get that blowing snow that the visibility is impacted.”
Elsewhere in the state, strong winds combined with falling snow can create blizzard conditions for 12 hours or more, VandenBoogart said, mentioning Natrona and Johnson counties as locations where blizzard conditions are more common and longer-lasting.
VandenBoogart also noted that the distinction between NWS advisories and warnings is significant, and that warnings should be taken seriously.
“An advisory means we expect moderate impact to life and travel,” he said. “Warnings are high impact. When the weather service issues a winter storm warning, they are concerned about high impact to life and travel. We’re saying it could be hazardous, and please make alternate plans.”
