Posted at 12:47 p.m., May 4, 2015

percipitationgraphic

Rainbow at noon, more rain soon

April showers bring May flowers...yeah, right. Let’s be honest: Wyoming isn’t known for its nice, consistent weather. But if this spring has been any indicator of future climates, Cheyenne may very well have a pleasant summer ahead.

According to multiple databases’ study results, the weather in Cheyenne for May, June and July should be nothing to worry about. Precipitation levels are being forecast above normal and temperatures could go either way, both positive signs of a low wildfire season.

“This year, based on what the Climate Prediction Center is showing, we should be above normal overall for May, June and July,” Steve Rubin, meteorologist at the National Weather Service Cheyenne, said of the predictions.

While this summer’s precipitation levels are expected to be above normal, the anticipated temperatures are categorized as equal chance, meaning, statistically, there is an equal chance temperatures could be either below or above normal.

Even though this summer’s weather has yet to be completely determined, May 2014’s Mother’s Day snowstorm leaves some individuals weary of the month ahead. “We had an above normal May last year,” Rubin said of the snow and precipitation, both of which broke records last year at 1.22 inches of precipitation and 10.5 inches of snowfall in 24 hours.

Spring brings variable weather

Spring is the time of year that has the most variable weather, Rubin said. “It’s an exciting time of year for weather forecasting because the weather changes so drastically,” he explained.

Along with current summer predictions, the pattern set by Cheyenne’s April showers (both snow and rain) tends to forecast a wetter May, June and July than were seen in 2014. No droughts are expected this year, and haven’t actually been seen in Cheyenne as often as some might think.

To be considered a drought, there must be a substantial lack of precipitation for a sustained period, about “two or three months below normal,” Rubin said. The last drought Cheyenne saw was in 2013, when the precipitation totaled 2.76 inches, No. 5 on the Lowest Total Precipitation in inches for the Cheyenne area since 1850.

However, Rubin said there could be a chance for floods this season. Prior to the mid-April snowstorm that caused both directions of Interstate 80 between Cheyenne and Laramie to close for several days, the mountain snowpack was 70 percent of normal capacity. After the storm, the snowpack saw an increase of more than 30 inches, raising it to 80 to 90 percent of normal capacity.

“It depends how quickly we warm up,” Rubin said. “This time of year we have to worry about the rivers flooding if the snow melts too quickly.”

New weather phenomenon

This April also saw the arrival of an uncommon phenomenon: thundersnow. “It’s a real phenomenon. It doesn’t happen that often,” Rubin said, then explained the occurrence as instability in the atmosphere where thunderstorm activity and snow showers interact.

“They call it thundersnow because it’s basically a thunderstorm, except it’s cold enough to snow. So, you can actually have snow falling, and you hear thunder,” Rubin explained. “It’s indicative of decent instability in the atmosphere combined with low temperatures.”

Thunder snow can also bring higher snowfall rates than usual snow, Rubin said. “Typically, you can get have an inch to an inch and a half an hour, but in a thunder snowstorm, you can get three inches per hour.”

As far as what this rare occurrence means for upcoming weeks, it could indicate a rise in summer thunderstorms. “If we get a lot of precipitation, like in April and May, then we have that moisture in the atmosphere, then we tend to get more severe weather in our peak severe weather season—the last two weeks of May, the first two weeks of June—so with all that moisture in the atmosphere, we tend to get more thunderstorms in the summertime,” Rubin said.

So far, residents can expect to see minimal fire weather concerns and less water usage from the reservoirs during the summer.

“This one looks pretty nice,” Rubin said. “It looks like a good summer.”


Storm Prediction Center