Winter Storm and Heavy Snow in Idaho, January 3 to 5, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
258 PM MST SAT JAN 3 2015

...MAJOR WINTER STORM TO HINDER TRAVEL LATE SUNDAY INTO MONDAY...

.DISCUSSION...CONFIDENCE IS HIGH THAT A VERY MOIST SYSTEM WILL
BRING HEAVY SNOW TO THE REGION SUNDAY NIGHT INTO MONDAY. BEFORE
THE PEAK OF THE MOISTURE INFLUX, WE WILL BE DEALING WITH MOIST
NORTHWEST FLOW TONIGHT THROUGH SUNDAY. POWDERY SNOW ACCUMULATIONS
BETWEEN 1 TO 3 INCHES IS EXPECTED WHILE A FEW AREAS ACROSS WEST-
CENTRAL MONTANA AND ACROSS THE CLEARWATER AND IDAHO COUNTIES OF
IDAHO COULD SEE 3 TO 5 INCHES. ROAD SURFACES WILL BE SNOW-COVERED
AND SLICK CONDITIONS ARE POSSIBLE.

SUNDAY EVENING THROUGH MONDAY WINTER STORM:

IMPACTS:
1)TOUGH TRAVEL FOR THE MONDAY MORNING COMMUTE, ESPECIALLY WITH
SCHOOLS RETURNING AND THE INCREASED RESIDUAL HOLIDAY TRAVEL. AREAS
MOST LIKELY IMPACTED WILL BE THE VALLEYS OF NORTHWEST MONTANA.  A
FEW ROADWAYS COULD BECOME IMPASSABLE FOR A PERIOD MONDAY MORNING
DUE TO HEAVY SNOWFALL ACROSS NORTHWEST MONTANA. IN WEST CENTRAL
MONTANA IT IS POSSIBLE (LOW TO MODERATE CONFIDENCE) PRECIPITATION
WILL STAY ALL SNOW IN MISSOULA MONDAY MORNING. IF SO THIS WOULD
BE ANOTHER MAJOR IMPACT AS SNOW AMOUNTS WOULD BE MORE THAN JUST A
FEW INCHES  SO STAY TUNED.

2)DENSE HEAVY WET SNOW COULD CAUSE PERIODS OF POWER OUTAGES
ESPECIALLY ACROSS NORTHWEST MONTANA.

3)I-90 CORRIDOR EAST OF LOOKOUT PASS AND US-93 SOUTH OF POLSON
COULD SEE A MIXTURE WITH RAIN OR CHANGE TO RAIN OR EVEN FREEZING
RAIN ON MONDAY CAUSING A MESS.

4)AVALANCHE DANGER - PLEASE GO TO THE FLATHEAD AVALANCHE CENTER AND
MISSOULA AVALANCHE CENTER WEB PAGES FOR FURTHER INFORMATION.

5)SNOWFALL MAY NOT END IN SOME AREAS LATER MONDAY INTO TUESDAY
ESPECIALLY ALONG THE CONTINENTAL DIVIDE...SEELEY AND SWAN AREAS
AND GLACIER PARK. CONFIDENCE IS LOW ON SNOWFALL AMOUNTS BUT IS
HIGH FOR CONTINUOUS SNOWFALL IN THESE AREAS.

SOME DETAILS:
A) HEAVY SNOWFALL: DEVELOPS SUNDAY EVENING AND CONTINUES THROUGH
MONDAY MORNING...1 TO 2 FEET OF SNOW IS EXPECTED FOR THE GLACIER
PARK INCLUDING US-2, ALONG HIGHWAY 200 FROM NORTHEAST OF BONNER TO
OVANDO, ALONG US-93 BETWEEN WHITEFISH AND EUREKA AND AT LOOKOUT
PASS. HIGHER ELEVATIONS WILL ALSO SEE SEVERAL FEET OUT OF THIS
STORM AND COMBINED WITH STRONG WESTERLY WINDS THERE COULD BE
AVALANCHE ISSUES. MUCH OF NORTHWEST MONTANA COULD BE UNDER THE GUN
IN TERMS OF HEAVY SNOWFALL WITH VALLEY AMOUNTS RANGING FROM 8 TO
14 INCHES.

B)FREEZING RAIN AND RAIN: AS THE ATMOSPHERIC RIVER OR MOIST PLUME
SHIFTS SOUTHWARD ON MONDAY, TEMPERATURES IN THE VALLEYS OF WEST-
CENTRAL AND SOUTHWEST MONTANA MAY EDGE ABOVE FREEZING. SOME
LOCATIONS COULD SEE FREEZING RAIN CAUSING UNTREATED SURFACES TO
BECOME SLICK. VALLEY LOCATIONS ACROSS CENTRAL IDAHO WILL SEE A
CHANGE TO FREEZING RAIN AND RAIN AS EARLY AS MIDNIGHT SUNDAY
NIGHT. SEVERAL INCHES OF SNOW IS POSSIBLE IN THE LOWER VALLEYS
BEFORE THE CHANGEOVER TO RAIN.

IF YOU NEED MORE DETAILS ABOUT THIS IMPENDING STORM, PLEASE GO TO
OUR WEATHER STORIES ON OUR WEB PAGE, POINT AND CLICK FORECASTS,
SOCIAL MEDIA PAGES. IF YOU NEED FURTHER INFORMATION DON'T
HESITATE TO GIVE US A CALL AT 406 329-4840.

TUESDAY...SNOW WILL LINGER OVER THE REGION THROUGH THE DAY WITH
FURTHER SNOW ACCUMULATIONS EXPECTED, ESPECIALLY IN THE MORNING
HOURS. SNOW LEVELS WILL REMAIN STEADY MUCH OF THE DAY.

WEDNESDAY AND THURSDAY...CONFIDENCE IS HIGH THAT A RIDGE OF HIGH
PRESSURE WILL BUILD OVER THE NORTHERN ROCKIES. THE STABLE
CONDITIONS AND RECENT PRECIPITATION WILL INCREASE THE POTENTIAL
FOR VALLEY FOG AND COLD POOLS TO FORM OVER THE NORTHERN ROCKIES.

FRIDAY AND SATURDAY...MODELS SIGNIFICANTLY DIVERGE WITH THEIR
SOLUTIONS. GIVEN THE HIGH UNCERTAINTY AND CONFIDENCE CLIMATOLOGY
WILL BE USED FOR THE FORECAST.

&&

.AVIATION...LIGHT SNOW WILL FALL PRETTY MUCH CONTINUOUSLY AT KGPI
FOR THE NEXT 24 HOURS. EAST WINDS ARE LIKELY TO INCREASE
OVERNIGHT, FURTHER SUSTAINING LOWER VISIBILITY. LIGHT SNOW WILL
LIKELY START LATER THIS EVENING IN MISSOULA AND SHOULD PERSIST
THROUGH MUCH OF SUNDAY. AGAIN, SOME REDUCTION IN VISIBILITY CAN BE
EXPECTED. SNOW IS NOT EXPECTED TO START UP AGAIN AT KBTM UNTIL
SUNDAY MORNING. THE CEILING WILL BE LOWER DUE TO THE SNOW, BUT
SHOULD NOT POSE ANY SIGNIFICANT ISSUES TO AVIATION INTERESTS. NO
SIGNIFICANT ISSUES ARE ANTICIPATED AT KSMN OVERNIGHT INTO SUNDAY.
IT SHOULD BE MENTIONED THAT AN EVEN MORE SIGNIFICANT STORM SYSTEM
WILL BRING VERY HEAVY SNOW TO KGPI AND KMSO STARTING LATE SUNDAY
NIGHT AND CONTINUING WELL INTO THE BEGINNING OF THE WEEK.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH TUESDAY MORNING
     BUTTE/BLACKFOOT REGION.

     WINTER STORM WARNING FROM 5 PM SUNDAY TO 11 AM MST TUESDAY ABOVE
     4000 FEET FOR THE BITTERROOT/SAPPHIRE MOUNTAINS.

     WINTER STORM WARNING FROM 5 PM SUNDAY TO 11 AM MST TUESDAY
     KOOTENAI/CABINET REGION...LOWER CLARK FORK REGION.

     WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH TUESDAY MORNING
     MISSOULA/BITTERROOT VALLEYS.

     WINTER STORM WARNING FROM 5 PM SUNDAY TO 11 AM MST TUESDAY
     FLATHEAD/MISSION VALLEYS.

     WINTER STORM WARNING FROM 5 PM SUNDAY TO 11 AM MST TUESDAY
     POTOMAC/SEELEY LAKE REGION...WEST GLACIER REGION.

ID...WINTER STORM WARNING FROM 4 PM SUNDAY TO 10 AM PST TUESDAY ABOVE
     4000 FEET FOR THE NORTHERN CLEARWATER MOUNTAINS...SOUTHERN
     CLEARWATER MOUNTAINS.

     WINTER WEATHER ADVISORY FROM 4 AM SUNDAY TO 4 AM PST MONDAY
     LOWER HELLS CANYON/SALMON RIVER REGION...
     OROFINO/GRANGEVILLE REGION.

&&