Storm Highlight of the Month – December 2007:

The month of December was ushered in with a powerful winter storm that hit the entire Pacific Northwest, including the Northern Rockies. Massive flooding and mudslides in portions of Oregon and Washington gave way to heavy snow, particularly across northwest Montana and north-central Idaho. Final snowfall totals of a foot were not uncommon over a 36 hour period spanning December 1^st and 2^nd, with a few locations measuring in excess of 2 to 3 feet of snow! Additionally, strong winds accompanied the system, pounding much of the Northern Rockies with wind gusts between 40 and 50 mph. These winds aggravated the situation in the Grangeville area in Idaho, stirring up snow and causing a period of blizzard conditions on the prairie.

Radar image on the afternoon of December 2^nd. Notice the widespread precipitation

evident across the Idaho panhandle. Although northwest Montana looks free and

clear of precipitation, heavy snow was falling at this time. This lack of returns is a

common problem in the winter due to the low toped nature of winter precipitation.

So what exactly is to blame for all this snow? The main culprit was a warm front that moved through the region the evening of the 1^st into the morning of the 2^nd. The front provided sufficient lift and moisture to support the development of moderate to heavy snowfall ahead of it. In this case, the front stalled as it moved across northwest Montana and north-central Idaho, keeping the focus for snow over this area for quit some time. From Missoula southward, rain was experienced in the valleys due to warmer air at the surface. However, in northwest Montana and north central Idaho, a bubble of cold air remained trapped at the surface, allowing heavy snow to fall all the way down to even the lowest valley locations. In fact, valley locations across portions of northwest Montana received as much as 2 to 3 feet during this time frame!

Surface analysis from the morning of December 2^nd. Notice the warm front pushing northward through the

region. This feature played a major role in the heavy amounts of snow and high winds experienced across

the area.

Below is a summary of snow and wind reports received from this event.

Storm Reports:

Location	Elevation	Snowfall
Northern Clearwater Mountains – Idaho
Cool Creek	6279’	43”
Hemlock Butte	5810’	31”
Shanghai Summit	4600’	17”
Pierce	3185’	5”
Headquarters	3165’	8”
Southern Clearwater Mountains – Idaho
Savage Pass	6171’	18”
Dixie	5620’	13”
Lolo Pass	5239’	20”
Powell	3530’	7”
Eastern Lemhi County – Idaho
Meadow Lake	9199’	9”
Moonshine	7500’	5”
Moose Creek	6201’	14”
Kootenai/ Cabinet Region – Montana
Hawkins Lake	6450’	18”
Banfield Mountain	5600’	19”
Poorman Creek	5098’	28”
Garver Creek	4249’	20”
Olney	3165’	12”
Yaak	3075’	21-28”
Eureka	2800’	4”
Libby	2070’	16-18”
Troy	1950’	30-36”
West Glacier Region – Montana
Badger Pass	6900’	13”
Flattop Mountain	6299’	26”
Stahl Peak	6030’	13”
Emery Creek	4350’	15”
1 N Polebridge	3540’	16”
West Glacier to Essex	3200’	12-14”
Lower Clark Fork Region – Montana
Hoodoo Basin	6050’	35”
Lookout Pass	5121’	33”
Alberton	3060’	4”
Thompson Falls	2380’	11”
Heron	2100’	16”
Bitterroot/ Sapphire Mountains - Montana
Saddle Mountain	7900’	18”
Twin Lakes	6401’	25”
Nez Perce Camp	5640’	20”
Twelvemile Creek	5600’	20”

Location	Elevation	Peak wind (mph)
Southern Clearwater Mountains - Idaho
Lodgepole	6100’	S 9G29
Red River	4600’	E 5G30
Lolo Pass	5237’	S 16G22
Orofino/ Grangeville Region – Idaho
Mt. Idaho	6110’	SE 44G66
1 N Grangeville	3310’	S 34G54
Orofino	1339’	SE 13G24
Lower Hells Canyon/ Salmon River – Idaho
Slate Creek	1568’	SW 20G56
Pittsburg Landing	1357’	SE 12G38
Eastern Lemhi County – Idaho
Ezra Creek	6660’	SW 29G42
Leadore Creek	6150’	SE 19G35
Kriley Creek	5200’	S 29G49
Salmon	5100’	SW 24G38
Kootenai/ Cabinet Region – Montana
Eureka Airport	2668’	SE 23G32
Flathead/ Mission Valleys – Montana
Pablo Dam	3173’	S 17G32
Ronan	3086’	SE 26G35
Glacier Park Air (Kalispell)	2972’	S 21G31
Creston	2950’	S 18G32
Woods Bay	2949’	G 39
Saint Ignatius	2940’	S 18G38
Blue Bay	2892’	G33
Lower Clark Fork Region – Montana
Lookout Pass	4725’	SE 16G52
Pardee	4570’	S 17G32
Nine Mile	3267’	SE 10G30
Thompson Falls	2460’	E 21G28
Missoula/ Bitterroot Valleys – Montana
Corvallis	3597’	S 12G29
Stevensville	3365’	SE 11G25
Missoula Airport	3189’	S 25G36
Bitterroot/ Sapphire Mountains – Montana
Deer Mountain	7282’	S 26G43
Tepee Point	6629’	S 21G42
Sula	4570’	SE 11G25
Butte/ Blackfoot Region – Montana
McDonald Pass	6325’	W 33G43
Butte	5545’	S 26G35
Phillipsburg	5280’	S 18G27
Anaconda	5102’	SE 21G29
Avon	5085’	S 34G42
Deer Lodge	4680’	SE 20G36
Garrison	4330’	SE 14G29