847  
FWUS45 KMSO 201131  
SAGMSO  
 
BACKCOUNTRY FORECAST FOR WESTERN MONTANA AND NORTH CENTRAL IDAHO  
NATIONAL WEATHER SERVICE MISSOULA MT  
431 AM MST TUE FEB 20 2018  
 
DISCUSSION:  
 
A SLOWLY MODIFYING ARCTIC AIRMASS WILL REMAIN OVER THE NORTHERN  
ROCKIES FOR THE NEXT SEVERAL DAYS AS TEMPERATURES REMAIN 15 TO 20  
DEGREES BELOW NORMAL. A TROUGH OF LOW PRESSURE DIGS INTO THE  
PACIFIC NORTHWEST THIS AFTERNOON. THE BULK OF THE ENERGY WILL BE  
OVER WASHINGTON THIS AFTERNOON AND EVENING, BUT ENOUGH INSTABILITY  
WILL BE OVER NORTHWEST MONTANA TO CREATE A FEW SNOW SHOWERS. NEW  
SNOW ACCUMULATIONS WILL BE LIGHT, FROM A DUSTING TO POTENTIALLY AN  
INCH. THIS TROUGH SWINGS THROUGH OREGON INTO CENTRAL IDAHO TONIGHT  
INTO WEDNESDAY. IDAHO COUNTY INTO SOUTHWEST MONTANA APPEARS TO  
HAVE THE BEST CHANCE FOR SNOW, BUT MOISTURE CONTINUES TO BE  
LIMITED. THE HIGHER TERRAIN OF IDAHO COUNTY IS ONLY EXPECTED TO  
RECEIVE UP TO 2 INCHES OF NEW SNOW. THE NORTHERN ROCKIES REMAIN  
UNDER A COLD AND ACTIVE WEATHER PATTERN THROUGH THE END OF THE  
WORK WEEK AS SUBTLE FEATURES PUSH THROUGH THE REGION IN  
NORTHWESTERLY FLOW. A MORE SIGNIFICANT SYSTEM IS ANTICIPATED FOR  
THE WEEKEND.  
 

 
ELEVATIONS ABOVE 4,000 FT:  
 
TODAY TONIGHT WED  
CLOUD COVER 65% 80% 35%  
HI/LO TEMPS 5 TO 16 -15 TO -1 10 TO 22  
WINDS(MPH) W 5 SW 4 SW 6G18  
PRECIP CHC 0 0 0  
PRECIP TYPE SNOW SNOW SNOW  
LIQUID AMT 0.00 0.00 0.00  
SNOW RATIO(SLR) 23:1 22:1 23:1  
SNOW AMT(IN) 0 0 0  
 
SNOW LEVEL 0 0 0  
 

 
 
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