CHEYENNE – Meteorologists from the National Weather Service say a potent Pacific storm system will push across the state today and tonight, bringing a chance for strong to severe thunderstorms to southeast Wyoming.
Southeast Wyoming is under a marginal risk for severe storms today, basically east of the Laramie Range, according to Brandon Wills, a meteorologist at the NWS office in Cheyenne.
“We have an upper level system that’s going to be moving down over southeast Wyoming (today),” Wills said. “It’s a cold front that essentially is going to cause some possibility for severe weather around Cheyenne in the late afternoon.”
Threats associated with storms will be damaging winds, heavy rain leading to flash flooding concerns and frequent lightning. A few storms may also contain hail up to the size of quarters.
“Tornadoes are not looking to be part of the problem,” he said. “(Friday) was a good example of what we might see. We had some strong gusty winds in the area with occasional downpours. That’s what we’re looking at for (today) also.”
Wills said those enjoying outdoor activities today should keep their eyes on the skies between 3-8 p.m. for possible severe weather.
“I would definitely recommend that they have a way to receive weather updates and warnings whether that’s NOAA weather radio, smartphones, tablets or mobile devices,” he said. “The later in the evening it gets, the less chance we’ll have of severe weather.”
Expect temperatures to warm into the low 70s today, with lows expected in the upper 40s tonight.
Much drier air will quickly move in from the southwest behind the system, bringing the areas of critical fire weather conditions over southeast Utah due to wind and low relative humidity.
Labor Day heat
If you thought Labor Day weekend weather seemed warmer than usual, you were right.
Cheyenne’s high temperature of 95 degrees on Sept. 2 exceeded the previous record high of 92 degrees set in 1947, according to NWS. The 95 degree temperature also tied the all-time record high for September.
Cheyenne’s high temperature of 94 degrees on Sept. 1 was one degree shy of the record high of 95 degrees set in 1995.
“When we have high pressure, it’s a clockwise flow of air, which is the opposite of a low pressure system,” Wills said. “When we have a clockwise airflow pattern, it brings really dry and hot temperatures from Mexico and the southern area. Without anything around to make the atmosphere unstable, it can get really warm.”
Red Flag Warnings were in effect for much of Wyoming during the Labor Day weekend.
The month of August was warmer and drier than normal, according to NWS statistics.
Cheyenne’s average maximum temperature for the month was 85.1 degrees – that’s 3.9 degrees warmer than the normal value of 81.2 degrees. Last year’s average maximum temperature for August was 80.6 degrees.
The average minimum temperature for August was 55.8 degrees. That was slightly warmer than the normal value of 54.1. Last year’s average minimum temperature for the month was 52.7 degrees.
The NWS office in Cheyenne received 0.45 inches of rainfall in August, about an inch-and-a-half less then the normal rainfall of 1.95 inches. Cheyenne received 2.71 inches of precipitation in August 2018.
The period used by NWS to determine normal climate values is from 1981-2010.
Looking ahead a bit
Cheyenne could see fall-like conditions arrive slightly late this year, possibly around early October, Wills said.
“We’re thinking that we’re not going to have our first snowfall possibly until later on in October,” he said. “Sometimes we have snow events early in October, sometimes in September, but it doesn’t look that way from what we’ve been observing so far.”
Wills added that it’s going to be “a short fall when it does happen.”
“We certainly do have a string of cold fronts that will have us go into the 40s for overnight lows in the next week or so,” he said. “But as far as breaking away from these 80 and 90 degree temperatures, that’s at least two to four weeks away.”