945 
FXUS65 KMSO 152202
AFDMSO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
302 PM MST FRI JAN 15 2010

.DISCUSSION...CLOUD COVER AND PRECIPITATION IS INCREASING IN NORTHWEST
MONTANA AT THIS HOUR AS SOUTHWEST FLOW ALOFT CONTINUES TO STREAM
MOISTURE INTO THE NORTHERN ROCKIES TONIGHT THROUGH SATURDAY. SEVERAL
WEATHER-RELATED IMPACTS ARE ANTICIPATED.

STRONG SOUTH WINDS IN PORTIONS NORTH CENTRAL IDAHO AND SOUTHWEST
MONTANA ARE EXPECTED TO REMAIN STRONG THROUGH EARLY EVENING. THE
TIGHTENED SURFACE PRESSURE GRADIENT IS OCCURRING AS A RESPONSE TO THE
SYSTEM CURRENTLY TRACKING INTO NORTHWEST MONTANA IN ADDITION TO
UNSTABLE SURFACE CONDITIONS. WINDS ARE EXPECTED TO DISSIPATE LATE
THIS EVENING. WIND ADVISORIES FOR THE AFFECTED AREAS MENTIONED
ABOVE REMAIN IN EFFECT THROUGH THIS EVENING...WITH WINDS EXPECTED TO
DISSIPATE LATE THIS EVENING. 

PRECIPITATION ACROSS NORTHWEST MONTANA TONIGHT IS EXPECTED TO BE IN
THE FORM OF SNOW OR A RAIN SNOW MIX AS AIR ALOFT REMAINS COOL WITH
THE PASSAGE OF A SURFACE FRONT. IN NORTH CENTRAL IDAHO...RAIN OR A
RAIN SNOW MIX SHOULD BE THE PRIMARY FORM OF PRECIPITATION.
INCREASED CLOUD COVER WILL KEEP TEMPERATURES RELATIVELY MILD
OVERNIGHT...THUS KEEPING A SLIGHT CHANCE OF FREEZING RAIN IN THE
FORECAST FOR THE VALLEYS OF NORTHWEST MONTANA AND NORTHERN
CLEARWATERS IN IDAHO DURING THE OVERNIGHT AND SATURDAY MORNING
TIMEFRAME.

ADDITIONAL OROGRAPHIC LIFT ALONG WITH A 90 KNOT JET STREAK WILL
ENHANCE SNOWFALL IN THE HIGHER TERRAIN OF NORTHWEST MONTANA...
PARTICULARLY ALONG THE CONTINENTAL DIVIDE NEAR GLACIER PARK TONIGHT.
SOUTHWEST WINDS WILL BECOME VERY STRONG LATE THIS EVENING IN RESPONSE
TO THE JET STREAK OVERHEAD AND THE SURFACE FRONT PASSAGE TOWARD
SATURDAY MORNING. THE COMBINATION OF SNOW AND STRONG WINDS WILL
CREATE WHITEOUT CONDITIONS AND HAZARDOUS DRIVING LATE THIS EVENING
THROUGH LATE SATURDAY MORNING. A WINTER WEATHER ADVISORY HAS BEEN
ISSUED FOR MARIAS PASS FOR SNOW AND BLOWING SNOW. 

FOR THE LATEST INFORMATION ON CURRENT ADVISORIES FOR THE
MISSOULA WARNING AREA...PLEASE REFER TO WWW.WEATHER.GOV/MISSOULA.

SATURDAY NIGHT THROUGH MONDAY NIGHT...A CLASSIC EL NINO WEATHER
PATTERN CONTINUES TO BE DEPICTED FOR THE MID TERM FORECAST
PERIODS...WITH EMBEDDED WEAK DISTURBANCES MOVING WITHIN A
PERSISTENT SOUTHWESTERLY FLOW OVER THE NORTHERN ROCKIES.
PRECIPITATION IS POSSIBLE FOR MUCH OF THIS PERIOD...WITH EXCEPTION
OF EARLY SUNDAY...WHEN SATURATED AIR WITHIN VALLEYS WILL ALLOW FOG
AND FREEZING FOG TO DEVELOP. IN THE ABSENCE OF ROBUST STORM SYSTEM
FEATURES...PRECIPITATION AMOUNTS ARE NOT EXPECTED TO BE
IMPRESSIVE. THE RELATIVELY WARM NATURE OF THE SOUTHWESTERLY FLOW
WILL KEEP VALLEYS WITH A MIXTURE OF RAIN...SNOW...AND OCCASIONAL
FREEZING RAIN. NORTHWEST MONTANA APPEARS MOST FAVORED FOR FREEZING
RAIN...WITH MODEL GUIDANCE DEPICTING RIDGE TOP TEMPERATURES
HOVERING NEAR FREEZING FOR MUCH OF THE MID TERM. ALSO...WITH
LITTLE LOW LEVEL DRYING AND WATER REMAINING ON THE GROUND AND ROAD
SURFACES OF AREA VALLEYS... OVERNIGHT REFREEZING MAY RESULT IN
SUDDEN HAZARDOUS ROAD CONDITIONS DEVELOPING. TEMPERATURES WILL BE
ABOVE NORMAL FOR THE MID TERM AS WELL.

TUESDAY THROUGH FRIDAY...MODELS HAVE REMAINED CONSISTENT THROUGH
THIS PERIOD. THE LOW WILL REMAIN OFF OF THE NORTHERN PACIFIC
COAST. THIS WILL CONTINUE TO PUSH WAVES OF PRECIPITATION ACROSS
THE REGION.

&&

.AVIATION...A MOIST SOUTHWEST FLOW ALOFT WILL USHER PRECIPITATION
ACROSS NORTHWEST MONTANA AND THE IDAHO PANHANDLE TONIGHT. THIS
WILL CREATE LOWERED CEILINGS AND VISIBILITY...CAUSING THE HIGHER
TERRAIN TO BE OBSCURED THROUGH SATURDAY. AIRFIELD KGPI CAN EXPECT
REDUCED CEILINGS AND VISIBILITY IMPACTS DUE TO PRECIPITATION TO BEGIN
AROUND 16/0500Z. THE MAIN PRECIPITATION TYPE EXPECTED WILL BE A
RAIN SNOW MIX IN THE VALLEY LOCATIONS...HOWEVER PATCHY FREEZING
RAIN IS NOT OUT OF THE QUESTION AFTER 16/0600Z. ACROSS SOUTHWEST
MONTANA AND CENTRAL IDAHO...STRONG SOUTH TO SOUTHWEST WINDS WILL
CONTINUE INTO THE EVENING HOURS. WINDS ARE EXPECTED TO DECREASE
AFTER 16/0300Z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 11 AM MST 
     SATURDAY FOR WEST GLACIER REGION.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR BUTTE/BLACKFOOT 
     REGION.

ID...WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR 
     OROFINO/GRANGEVILLE REGION.

     WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR LOWER HELLS 
     CANYON/SALMON RIVER REGION.

&&

$$

SHORT TERM...DEROSA/PALLISTER
LONG TERM....ZUMPFE/KOLATA
AVIATION...PALLISTER

276 
FXUS65 KMSO 152213 CCA
AFDMSO

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE MISSOULA MT
302 PM MST FRI JAN 15 2010

.DISCUSSION...CLOUD COVER AND PRECIPITATION IS INCREASING IN NORTHWEST
MONTANA AT THIS HOUR AS SOUTHWEST FLOW ALOFT CONTINUES TO STREAM
MOISTURE INTO THE NORTHERN ROCKIES TONIGHT THROUGH SATURDAY. SEVERAL
WEATHER-RELATED IMPACTS ARE ANTICIPATED.

STRONG SOUTH WINDS IN PORTIONS NORTH CENTRAL IDAHO AND SOUTHWEST
MONTANA ARE EXPECTED TO REMAIN STRONG THROUGH EARLY EVENING. THE
TIGHTENED SURFACE PRESSURE GRADIENT IS OCCURRING AS A RESPONSE TO THE
SYSTEM CURRENTLY TRACKING INTO NORTHWEST MONTANA IN ADDITION TO 
UNSTABLE SURFACE CONDITIONS. WIND ADVISORIES FOR THE AFFECTED AREAS 
MENTIONED ABOVE REMAIN IN EFFECT THROUGH THIS EVENING...WITH WINDS 
EXPECTED TO DISSIPATE THEREAFTER. 

PRECIPITATION ACROSS NORTHWEST MONTANA TONIGHT IS EXPECTED TO BE IN
THE FORM OF SNOW OR A RAIN SNOW MIX AS AIR ALOFT REMAINS COOL WITH
THE PASSAGE OF A SURFACE FRONT. IN NORTH CENTRAL IDAHO...RAIN OR A
RAIN SNOW MIX SHOULD BE THE PRIMARY FORM OF PRECIPITATION.
INCREASED CLOUD COVER WILL KEEP TEMPERATURES RELATIVELY MILD
OVERNIGHT...THUS KEEPING A SLIGHT CHANCE OF FREEZING RAIN IN THE
FORECAST FOR THE VALLEYS OF NORTHWEST MONTANA AND NORTHERN
CLEARWATERS IN IDAHO DURING THE OVERNIGHT AND SATURDAY MORNING
TIMEFRAME.

ADDITIONAL OROGRAPHIC LIFT ALONG WITH A 90 KNOT JET STREAK WILL
ENHANCE SNOWFALL IN THE HIGHER TERRAIN OF NORTHWEST MONTANA...
PARTICULARLY ALONG THE CONTINENTAL DIVIDE NEAR GLACIER PARK TONIGHT.
SOUTHWEST WINDS WILL BECOME VERY STRONG LATE THIS EVENING IN RESPONSE
TO THE JET STREAK OVERHEAD AND THE SURFACE FRONT PASSAGE TOWARD
SATURDAY MORNING. THE COMBINATION OF SNOW AND STRONG WINDS WILL 
CREATE WHITEOUT CONDITIONS AND HAZARDOUS DRIVING ON HIGHWAY 2 OVER 
MARIAS PASS LATE THIS EVENING THROUGH LATE SATURDAY MORNING. A 
WINTER WEATHER ADVISORY HAS BEEN ISSUED FOR MARIAS PASS FOR SNOW AND 
BLOWING SNOW. 

FOR THE LATEST INFORMATION ON CURRENT ADVISORIES FOR THE
MISSOULA WARNING AREA...PLEASE REFER TO WWW.WEATHER.GOV/MISSOULA.

SATURDAY NIGHT THROUGH MONDAY NIGHT...A CLASSIC EL NINO WEATHER
PATTERN CONTINUES TO BE DEPICTED FOR THE MID TERM FORECAST
PERIODS...WITH EMBEDDED WEAK DISTURBANCES MOVING WITHIN A
PERSISTENT SOUTHWESTERLY FLOW OVER THE NORTHERN ROCKIES.
PRECIPITATION IS POSSIBLE FOR MUCH OF THIS PERIOD...WITH EXCEPTION
OF EARLY SUNDAY...WHEN SATURATED AIR WITHIN VALLEYS WILL ALLOW FOG
AND FREEZING FOG TO DEVELOP. IN THE ABSENCE OF ROBUST STORM SYSTEM
FEATURES...PRECIPITATION AMOUNTS ARE NOT EXPECTED TO BE
IMPRESSIVE. THE RELATIVELY WARM NATURE OF THE SOUTHWESTERLY FLOW
WILL KEEP VALLEYS WITH A MIXTURE OF RAIN...SNOW...AND OCCASIONAL
FREEZING RAIN. NORTHWEST MONTANA APPEARS MOST FAVORED FOR FREEZING
RAIN...WITH MODEL GUIDANCE DEPICTING RIDGE TOP TEMPERATURES
HOVERING NEAR FREEZING FOR MUCH OF THE MID TERM. ALSO...WITH
LITTLE LOW LEVEL DRYING AND WATER REMAINING ON THE GROUND AND ROAD
SURFACES OF AREA VALLEYS... OVERNIGHT REFREEZING MAY RESULT IN
SUDDEN HAZARDOUS ROAD CONDITIONS DEVELOPING. TEMPERATURES WILL BE
ABOVE NORMAL FOR THE MID TERM AS WELL.

TUESDAY THROUGH FRIDAY...MODELS HAVE REMAINED CONSISTENT THROUGH
THIS PERIOD. THE LOW WILL REMAIN OFF OF THE NORTHERN PACIFIC
COAST. THIS WILL CONTINUE TO PUSH WAVES OF PRECIPITATION ACROSS
THE REGION.

&&

.AVIATION...A MOIST SOUTHWEST FLOW ALOFT WILL USHER PRECIPITATION
ACROSS NORTHWEST MONTANA AND THE IDAHO PANHANDLE TONIGHT. THIS
WILL CREATE LOWERED CEILINGS AND VISIBILITY...CAUSING THE HIGHER
TERRAIN TO BE OBSCURED THROUGH SATURDAY. AIRFIELD KGPI CAN EXPECT
REDUCED CEILINGS AND VISIBILITY IMPACTS DUE TO PRECIPITATION TO BEGIN
AROUND 16/0500Z. THE MAIN PRECIPITATION TYPE EXPECTED WILL BE A
RAIN SNOW MIX IN THE VALLEY LOCATIONS...HOWEVER PATCHY FREEZING
RAIN IS NOT OUT OF THE QUESTION AFTER 16/0600Z. ACROSS SOUTHWEST
MONTANA AND CENTRAL IDAHO...STRONG SOUTH TO SOUTHWEST WINDS WILL
CONTINUE INTO THE EVENING HOURS. WINDS ARE EXPECTED TO DECREASE
AFTER 16/0300Z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 11 AM MST 
     SATURDAY FOR WEST GLACIER REGION.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR BUTTE/BLACKFOOT 
     REGION.

ID...WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR 
     OROFINO/GRANGEVILLE REGION.

     WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR LOWER HELLS 
     CANYON/SALMON RIVER REGION.

&&

$$

SHORT TERM...DEROSA/PALLISTER
LONG TERM....ZUMPFE/KOLATA
AVIATION...PALLISTER