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January was a disappointing month for snowpack in Montana

Posted at 8:38 AM, Feb 07, 2019
and last updated 2019-02-07 10:39:32-05
February 6th Snow Water
(MTN News image)

BOZEMAN – Periods of high-pressure during January resulted in sunny skies and above average temperatures in Montana, causing snowpack percentages to decline in many river basins, according to snow survey data collected by the USDA Natural Resources Conservation Service (NRCS).

This pattern broke down late in the month, and significant snowfall occurred across most of the state of Montana.

This much needed system of storms added 1.5″ to 3.5″ of Snow Water Equivalent (SWE) to the snowpack, helping some basins in central, south-central and southwest Montana to remain or improve to near to above normal for February 1.

Although the basin-wide snowpack percentages in Gallatin and Upper Yellowstone indicate near to above normal snowpack conditions, there are some areas in southern Montana that have been largely missed by this winter’s storms.

“The late month storms really helped some of the towns in southern Montana where tourism from snowmobiling is critical to the local economies,” said Lucas Zukiewicz, NRCS hydrologist for Montana. “The snowpack in both Cooke City and West Yellowstone was the lowest it’s been in quite a few years in mid-January, and news gets out.”

Fortunately, he said, the storms helped these areas to recover some by February 1, although snowpack remains below normal. Almost all basins east of the Divide have improved snowpack percentages from January 1, but some regions remain below normal for snowpack on February 1.

The western half of the state also benefited from the late January storms, but the river basins experienced decreases in snowpack percentages since January 1 and remain below normal for this date.

“The storms just weren’t enough in the western half of the state to make up for the deficits we’d experienced early in the winter,” Zukiewicz said. “Even with the impressive totals from the late month storms, snowfall ended up being below normal for the month of January.”

River basins in the northwest region of the state typically experience their “wettest” months of the year from early November through the end of January. Below normal snow totals in these areas for this date make recovery to “normal” snowpack conditions before runoff begins less likely.

“For example, the Flathead River basin would need to receive around 135% of normal snowfall between now and when the snowpack reaches peak accumulation, which typically occurs sometime in April,” Zukiewicz said. “While that’s not impossible, it would certainly take a major pattern shift from what we’ve seen so far this winter.”

Similar to last month, mountain temperatures were above average in January and could be one of the impacts the region is experiencing from the weak El Nino that is occurring this year. Whether it strengthens or weakens into the summer of 2019 is still to be determined, but long-range forecasts issued by NOAA continue to indicate above average temperatures for the February – April time-period.

“That’s something we’ll be keeping an eye on,” Zukiewicz said. “Early runoff doesn’t benefit anyone, so hopefully spring is cooler than anticipated.”

Official NRCS streamflow forecasts for April 1 – July 31 will begin on March 1 and will offer a glimpse into what we could expect this spring and summer.

Monthly Water Supply Outlook Reports can be found here after the fifth business day of the month:

Snow Water Equivalent

2/1/2019 % Normal % Last Year
Columbia River Basin 87 72
  Kootenai in Montana 81 72
  Flathead in Montana 83 72
  Upper Clark Fork 100 71
  Bitterroot 87 76
  Lower Clark Fork 84 74
Missouri River Basin 95 77
  Jefferson 91 72
  Madison 85  75
  Gallatin 106 80
  Headwaters Mainstem 111 75
  Smith-Judith-Musselshell 101 82
  Sun-Teton-Marias 82 71
  St. Mary-Milk 86 85
Yellowstone River Basin 95 73
  Upper Yellowstone 98 66
  Lower Yellowstone 93 82
West of Divide 87 72
East of Divide 93 74
Montana Statewide 91 73


2/1/2019 Monthly % Average Water Year % Average WY % of Last Year
Columbia River Basin 72 88 76
  Kootenai in Montana 65 77 69
  Flathead in Montana 72 88 72
  Upper Clark Fork 85 95 80
  Bitterroot 65 95 89
  Lower Clark Fork 66 89 79
Missouri River Basin 97 96 88
  Jefferson 82 91 92
  Madison 91 86 83
  Gallatin 105 114 95
  Headwaters Mainstem 132 103 82
  Smith-Judith-Musselshell 115 100 92
  Sun-Teton-Marias 92 90 73
  St. Mary-Milk 70 87 73
Yellowstone River Basin 92 96 83
  Upper Yellowstone 92 100 75
  Lower Yellowstone 89 93 94
West of Divide 72 88 76
East of Divide 92 93 83
Montana Statewide 83 92 79

-Meteorologist Mike Heard