New Year's Eve marked the 10th day in a row of below normal temperatures for Billings — an end-of-the-year freeze that bucked a trend that made 2012 its warmest, driest year in 78 years of recordkeeping.
“We think it’s the longest stretch of below-normal temperatures all year,” said Joe Lester, meteorologist at the National Weather Service Office in Billings.
Mean temperature for the year at 51.2 degrees was three degrees above average. Previous record for the hottest year in Billings was set at 50.6 in 1981.
Miles City, which reached a searing 111-degree all-time record on June 26, had its second-warmest year on record. Mean temperature there was 50.2 degrees in 2012. Only 1987 was warmer.
Heat records fell from January to the end of August in both cities, and Miles City saw a record high of 65 degrees as late as Nov. 21. July 3 was the hottest day of the year in Billings at 103 degrees. Miles City topped the century mark 18 times last summer.
Just as troubling was a yearlong drought. Billings received just 7.13 inches of precipitation in 2012, which is 6.53 inches less than normal. Previous record for the driest year in Billings was 7.9 inches set in 1948.
It all started with a dry winter, Lester wrote Monday in a summary of 2012 weather.
“Snowfall was below normal across the region,” he said. “This led to an early mountain snowmelt and extremely poor green-up during the spring, which in turn, helped to bring a hot spring and summer, and an early onset of the fire season.”
Relief didn’t come until October. Even October, with an early and welcome snowstorm, fell 0.04 inches behind normal for the month. But cool October was followed by a November that was 4.4 degrees warmer than normal. December, despite a cold snap that affected the last third of the month, was 1.2 degrees warmer and 0.23 inches drier than normal.
At the end of the year, south-central Montana was listed in “extreme” drought on federal and state drought monitoring sites. Most of Wyoming fell into the same category.
In its Dec. 18 report, the Montana Department of Natural Resources and Conservation put five counties in the extreme category — Yellowstone, Carbon, Big Horn, Treasure and Carter. One step below on drought alert were Stillwater, Rosebud, Powder River and Fallon counties. The NWS Climate Prediction Center forecasts some easing of the drought, except in extreme southeast Montana, in 2013.
Spring and fall, when most moisture hits the plains in Montana, were a big disappointment in 2012. March began the grim trend with a mean temperature 9.3 degrees warmer than normal. It was the warmest March on record with an average temperature of 47 degrees. By March 31, it was 80 degrees in Billings.
Then big precipitation deficits developed. In April, rainfall was an inch less than normal. In June, the total was almost 2 inches less than normal. Between Aug. 16 and Oct. 2, no measurable precipitation fell in Billings. The entire month of September, normally one of the city’s wetter months, produced only a trace.
“The stretch of 48 days was the third-longest on record,” Lester wrote.
On Oct. 3, the season’s first 2.3 inches of snow fell yielding 0.34 inches of moisture.
Although it seems counterintuitive given the worst Montana fire season since 1910, another characteristic of summer 2012 was lack of severe weather and thunderstorms, Lester said.
That directly related to poor green-up and low soil moisture, he said. Thunderstorms were reported on just 22 days in 2012 — the lowest since 1988, another year of drought and fire.
Snowfall in area mountains so far this winter is slightly below to slightly above normal. On Dec. 31, snowpack that feeds the Upper Yellowstone — the reach of river from Yellowstone National Park to Custer — was 107 percent of normal. On the Lower Yellowstone, fed by mountains in Wyoming, snowpack was at 93 percent of average. The most worrisome basin is the Tongue River, a tributary of the Lower Yellowstone, with 66 percent of its normal snowpack. The Tongue River Reservoir in southeast Montana, however, had 188 percent of its normal storage at the end of November.
The 10-day cold spree at the end of December could be a harbinger of a nastier winter to come. The Climate Prediction Center said there are some signs that south-central Montana could have colder and wetter-than-normal weather January through March.
Its prediction is based on a number of climate indicators including a downward trend in temperatures in the Pacific Ocean, Lester said. Despite the slight cooling, the center, predicts the next few months will remain El Nino/La Nina neutral. El Nino and La Nina are, respectively, warming and cooling trends in the Pacific that affect climate worldwide. La Nina can mean stormier weather in Montana.
The immediate forecast for Billings calls for below normal temperatures and up to a 50 percent chance of snow.