000
FXUS65 KMSO 150324
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
924 PM MDT SAT MAR 14 2009
...MODERATE TO HEAVY SNOW TO IMPACT MOUNTAIN PASSES LATE TONIGHT
THROUGH MONDAY...
.DISCUSSION...FORECAST UPDATE THIS EVENING IS BASED UPON ADJUSTMENT
OF THE ONSET OF SNOW IMPACTING THE AREA MAINLY LATER THAN SOONER AS
A STRONG JET STREAM ENTERING THE PACIFIC NORTHWEST CONTINUES TO
DIG TO THE SOUTHEAST INTO OREGON. THIS DIGGING JET IS SLOWING THE
PROGRESS OF PRECIPITATION INTO IDAHO AND WESTERN MT. ANOTHER ISSUE
TO COMPLICATE WINTER WEATHER HIGHLIGHTS TONIGHT THROUGH SUNDAY
EVENING IS SNOW LEVELS. WITH THE EXCEPTION OF EXTREME NORTHWEST MT
WHERE ENOUGH COLD AIR EXISTS TONIGHT TO HAVE SNOW IN THE LOWER
VALLEYS THROUGH MIDDAY SUNDAY...ELSEWHERE SNOW LEVELS WILL HOVER
AROUND 4500 TO 5000 FEET WITH LITTLE SNOW ACCUMULATIONS EXPECTED.
GUSTY SOUTHERLY WINDS ARE EXPECTED TO DEVELOP SUNDAY AS THE JET
STREAM BEGINS TO CROSS OVER IDAHO AND WESTERN MT. LASTLY...AS THE
STRONG COLD FRONT PUSHES THROUGH THE AREA SUNDAY NIGHT INTO
MONDAY...WINTER WEATHER CONDITIONS WILL DEVELOP IN ALL AREAS.
MARIAS PASS LOOKS TO GET THE BRUNT OF THIS SYSTEM WITH VERY STRONG
WESTERLY WINDS AND HEAVY SNOW. HOWEVER...LOOKOUT AND LOLO PASSES
ALSO HAVE THE POTENTIAL TO SEE HEAVY SNOW AS WELL. STAY TUNED AS
THIS SYSTEM IS STRONG ENOUGH TO IMPACT ALL MOUNTAIN PASSES OF
NORTH CENTRAL IDAHO AND WESTERN MONTANA THROUGH MONDAY.
&&
.AVIATION...CONSISTENT MID LEVEL CEILINGS AND SOME LIGHT
PRECIPITATION WILL DEVELOP BY EARLY THIS EVENING ACROSS NORTHERN
IDAHO AND FAR NORTHWEST MONTANA. LOWERING CEILINGS...TERRAIN
OBSCURATION...AND OCCASIONAL MVFR VISIBILITIES WILL CONTINUE
OVERNIGHT...PERSISTING THROUGH SUNDAY AS A MOIST SYSTEM PUSHES
THROUGH THE AREA. IN ADDITION...STRONG WINDS WILL DEVELOP
THROUGHOUT THE DAY SUNDAY IN ADVANCE OF A STRONG COLD FRONT
APROACHING FROM WASHINGTON.
&&
.PREV DISCUSSION... /ISSUED 239 PM MDT SAT MAR 14 2009/
DISCUSSION...A VIGOROUS PACIFIC STORM IS APPROACHING THE NORTHERN
ROCKIES...BUT MAY BE PROGRESSING JUST A LITTLE SLOWER THAN WAS
PREVIOUSLY EXPECTED. CLOUD COVER AND LIGHT PRECIPITATION ON THE
LEADING EDGE OF THE SYSTEM IS STARTING TO SHOW UP IN EASTERN
WASHINGTON AND THE PANHANDLE...BUT WILL NOT INTENSIFY MUCH UNTIL
THE THE SURFACE FRONT APPROACHES. THAT FEATURE IS STILL WEST OF
THE CASCADES. THE MOUNTAINS OF THE PANHANDLE AND FAR NORTHWEST
MONTANA WILL BEGIN SEEING MORE PERSISTENT SNOW EARLY THIS
EVENING...BUT WARM STARTING TEMPERATURES WILL KEEP ACCUMULATING SNOW
OUT OF THE VALLEYS UNTIL LATER TONIGHT. PRECIPITATION WILL SAG
SOUTH THROUGH THE EVENING...AND BEGIN TO ACCUMULATE IN THE
CLEARWATER AND CENTRAL BITTERROOT MOUNTAINS AROUND DARK.
OROGRAPHIC LIFT WILL SPREAD LIGHT SNOW TO THE MOUNTAINS ALONG THE
NORTHERN DIVIDE TONIGHT...BUT THE LARGE SCALE LIFT WILL REMAIN
CLOSER TO THE MONTANA/IDAHO BORDER. HOWEVER...THE LIFT THROUGH
THE EARLY PART OF THE EVENT DOES NOT LOOK LIKE A HEAVY SNOW
PRODUCER...BUT MORE OF A STEADY LIGHT TO MODERATE SNOWFALL.
A SECONDARY FRONT AND UPPER JET WILL MOVE OVER THE REGION SUNDAY
AFTERNOON. THIS COULD FURTHER INTENSIFY THE SNOW...AS WELL AS
INCREASE MOUNTAIN WINDS. THIS IS OF PARTICULAR CONCERN OVER THE
HIGHER IMPACT AREAS OF THE GLACIER PARK REGION...NAMELY HIGHWAY 2
FROM NEAR ESSEX TO MARIAS PASS. A WINTER STORM WATCH HAS BEEN
ISSUED FOR THAT AREA. IN THE WAKE OF THIS SECOND FRONT...THE FOCUS
OF THE PRECIPITATION WILL SLOWLY SAG SOUTH WITH THE UPPER LEVEL
JET. BY MONDAY...BEST CHANCES WILL BE OVER THE MOUNTAINS OF LEMHI
COUNTY AND SOUTHWEST MONTANA.
TUESDAY THROUGH SATURDAY...A PROGRESSIVE WESTERLY FLOW ALOFT WILL
BRING UNSETTLED WEATHER TO THE NORTHERN ROCKIES THROUGH NEXT
WEEKEND. NUMEROUS DISTURBANCES WILL COMBINE WITH PACIFIC MOISTURE
UNDER THIS FLOW PATTERN BRINGING ALMOST CONTINUOUS SNOW SHOWERS TO
THE HIGHER TERRAIN. IT WILL TAKE STRONGER SHORTWAVE TROUGH
FEATURES TO ALLOW FOR SHOWERS TO REACH MANY OF THE LARGER VALLEY
FLOORS...SO WILL CONTINUE TO MONITOR LATEST MODEL RUNS TO BETTER TIME
AND EVALUATE EACH FEATURE.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY UNTIL 3 PM MDT SUNDAY FOR
KOOTENAI/CABINET REGION-LOWER CLARK FORK REGION.
WINTER STORM WARNING FROM 6 AM SUNDAY TO 6 AM MDT MONDAY FOR
WEST GLACIER REGION.
WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT MDT
SUNDAY NIGHT FOR BITTERROOT/SAPPHIRE MOUNTAINS.
ID...WINTER WEATHER ADVISORY FROM 5 PM SUNDAY TO 11 AM PDT MONDAY FOR
NORTHERN CLEARWATER MOUNTAINS.
WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 11 PM PDT
SUNDAY FOR SOUTHERN CLEARWATER MOUNTAINS.
&&
$$
SHORT TERM...FELSCH
LONG TERM....KITSMILLER
AVIATION...DICKERSON
000
FXUS65 KMSO 142039
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
239 PM MDT SAT MAR 14 2009
.DISCUSSION...A VIGOROUS PACIFIC STORM IS APPROACHING THE NORTHERN
ROCKIES...BUT MAY BE PROGRESSING JUST A LITTLE SLOWER THAN WAS
PREVIOUSLY EXPECTED. CLOUD COVER AND LIGHT PRECIPITATION ON THE
LEADING EDGE OF THE SYSTEM IS STARTING TO SHOW UP IN EASTERN
WASHINGTON AND THE PANHANDLE...BUT WILL NOT INTENSIFY MUCH UNTIL
THE THE SURFACE FRONT APPROACHES. THAT FEATURE IS STILL WEST OF
THE CASCADES. THE MOUNTAINS OF THE PANHANDLE AND FAR NORTHWEST
MONTANA WILL BEGIN SEEING MORE PERSISTENT SNOW EARLY THIS
EVENING...BUT WARM STARTING TEMPERATURES WILL KEEP ACCUMULATING SNOW
OUT OF THE VALLEYS UNTIL LATER TONIGHT. PRECIPITATION WILL SAG
SOUTH THROUGH THE EVENING...AND BEGIN TO ACCUMULATE IN THE
CLEARWATER AND CENTRAL BITTERROOT MOUNTAINS AROUND DARK.
OROGRAPHIC LIFT WILL SPREAD LIGHT SNOW TO THE MOUNTAINS ALONG THE
NORTHERN DIVIDE TONIGHT...BUT THE LARGE SCALE LIFT WILL REMAIN
CLOSER TO THE MONTANA/IDAHO BORDER. HOWEVER...THE LIFT THROUGH
THE EARLY PART OF THE EVENT DOES NOT LOOK LIKE A HEAVY SNOW
PRODUCER...BUT MORE OF A STEADY LIGHT TO MODERATE SNOWFALL.
A SECONDARY FRONT AND UPPER JET WILL MOVE OVER THE REGION SUNDAY
AFTERNOON. THIS COULD FURTHER INTENSIFY THE SNOW...AS WELL AS
INCREASE MOUNTAIN WINDS. THIS IS OF PARTICULAR CONCERN OVER THE
HIGHER IMPACT AREAS OF THE GLACIER PARK REGION...NAMELY HIGHWAY 2
FROM NEAR ESSEX TO MARIAS PASS. A WINTER STORM WATCH HAS BEEN
ISSUED FOR THAT AREA. IN THE WAKE OF THIS SECOND FRONT...THE FOCUS
OF THE PRECIPITATION WILL SLOWLY SAG SOUTH WITH THE UPPER LEVEL
JET. BY MONDAY...BEST CHANCES WILL BE OVER THE MOUNTAINS OF LEMHI
COUNTY AND SOUTHWEST MONTANA.
TUESDAY THROUGH SATURDAY...A PROGRESSIVE WESTERLY FLOW ALOFT WILL
BRING UNSETTLED WEATHER TO THE NORTHERN ROCKIES THROUGH NEXT
WEEKEND. NUMEROUS DISTURBANCES WILL COMBINE WITH PACIFIC MOISTURE
UNDER THIS FLOW PATTERN BRINGING ALMOST CONTINUOUS SNOW SHOWERS TO
THE HIGHER TERRAIN. IT WILL TAKE STRONGER SHORTWAVE TROUGH
FEATURES TO ALLOW FOR SHOWERS TO REACH MANY OF THE LARGER VALLEY
FLOORS...SO WILL CONTINUE TO MONITOR LATEST MODEL RUNS TO BETTER TIME
AND EVALUATE EACH FEATURE.
&&
.AVIATION...CONSISTENT MID LEVEL CEILINGS AND SOME LIGHT
PRECIPITATION WILL DEVELOP BY EARLY THIS EVENING ACROSS NORTHERN
IDAHO AND FAR WESTERN MONTANA. IMPACTS TO AVIATION DUE TO LOWERING
CEILINGS...TERRAIN OBSCURATIONS...AND OCCASIONAL MVFR
VISIBILITIES WILL DEVELOP PRIMARILY AFTER DARK...THEN LIKELY
PERSIST THROUGH SUNDAY AS A MOIST SYSTEM PUSHES THROUGH THE AREA.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO MIDNIGHT MDT
SUNDAY NIGHT FOR BITTERROOT/SAPPHIRE MOUNTAINS.
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 3 PM MDT
SUNDAY FOR KOOTENAI/CABINET REGION-LOWER CLARK FORK REGION.
WINTER STORM WATCH FROM SUNDAY AFTERNOON THROUGH LATE SUNDAY
NIGHT FOR WEST GLACIER REGION.
ID...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 11 PM PDT
SUNDAY FOR NORTHERN CLEARWATER MOUNTAINS-SOUTHERN
CLEARWATER MOUNTAINS.
&&
$$
SHORT TERM...WHITMORE
LONG TERM....KITSMILLER
AVIATION...WHITMORE
000
FXUS65 KMSO 140936
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
336 AM MDT SAT MAR 14 2009
.DISCUSSION...
TODAY THROUGH MONDAY...A POWERFUL PACIFIC STORM SYSTEM IS
ANTICIPATED TO BRING WINTER WEATHER IMPACTS TO THE REGION DURING THE
NEXT SEVERAL DAYS. ACCUMULATING SNOW POTENTIAL WILL INITIALLY EXIST
ACROSS NORTHWEST MONTANA THIS AFTERNOON...SPREADING SOUTH OVER NORTH
CENTRAL IDAHO DURING THIS EVENING. THE WARM NATURE OF THIS SYSTEM
WILL LIKELY CONFINE MODERATE TO SIGNIFICANT SNOW ACCUMULATIONS ABOVE
3500 FEET ELEVATION...HOWEVER SNOW LEVELS WILL DROP TO LOW
ELEVATIONS IMMEDIATELY FOLLOWING THE SURFACE COLD FRONT EARLY SUNDAY
MORNING. WINTER WEATHER HIGHLIGHT REMAIN IN EFFECT FOR PORTIONS OF
WESTERN MONTANA AND NORTH CENTRAL IDAHO FOR SNOW ACCUMULATION. FROM
THIS EVENING THROUGH MONDAY...THE PACIFIC JET STREAM WILL SLOWLY
MOVE SOUTHWARD...FOCUSING PRECIPITATION ON LOCATION UNDERNEATH THIS
INTENSE FEATURE. OVER TIME...GUIDANCE HAS INCREASED THE LIKELIHOOD
AND AMOUNT OF FORECAST PRECIPITATION. THE CURRENT FORECAST PACKAGE
REFLECTS THIS INCREASED CONFIDENCE IN TEMPORAL AND SPATIAL EXTENT OF
PRECIPITATION.
MONDAY NIGHT THROUGH FRIDAY...A STRONG JET STREAM COMING INTO
THE PACIFIC NORTHWEST IS EXPECTED TO DOMINATE THE NORTHERN ROCKIES
WEATHER INTO MIDWEEK. THIS WILL RESULT IN MOUNTAIN SNOW AND VALLEY
SHOWERS. TEMPERATURES EARLY IN THE WEEK WILL BE A LITTLE BELOW
NORMAL WITH VALLEYS REACHING THE 40S IN THE AFTERNOON. LATER IN
THE WEEK HOWEVER...COMPUTER MODEL TRENDS POINT TO MUCH MILDER AND
DRIER AIR MOVING IN.
&&
.AVIATION...
CLOUDS WILL INCREASE AND CEILINGS LOWER DURING THE NEXT 24
HOURS...AS A PACIFIC STORM SYSTEM ENTERS THE REGION. CEILINGS WILL
GRADUALLY LOWER TO BELOW MOUNTAINTOP AFTER 14/1800Z ACROSS THE
REGION...WITH SNOW AND RAIN DEVELOPING OVER NORTHWEST MONTANA BY
14/2100Z. THIS RAIN AND SNOW WILL SPREAD SOUTH AND EAST OVER
TIME...ACCOMPANIED BY LOW CEILINGS THAT WILL LIKELY OBSCURE TERRAIN
FEATURES THROUGH THE REMAINDER OF THE FORECAST PERIOD.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 PM MDT
SUNDAY FOR BITTERROOT/SAPPHIRE MOUNTAINS.
WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 3 PM MDT
SUNDAY FOR KOOTENAI/CABINET REGION-LOWER CLARK FORK REGION.
ID...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 8 PM PDT
SUNDAY FOR NORTHERN CLEARWATER MOUNTAINS-SOUTHERN
CLEARWATER MOUNTAINS.
&&
$$
SHORT TERM...ZUMPFE
LONG TERM....KOLATA
AVIATION...ZUMPFE
000
FXUS65 KMSO 132042
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
242 PM MDT FRI MAR 13 2009
.DISCUSSION...
TONIGHT THROUGH SUNDAY...HIGH PRESSURE WILL REMAIN THE DOMINANT
WEATHER FEATURE DURING THE OVERNIGHT TONIGHT...WITH MOSTLY CLEAR
SKIES AND LIGHT AND VARIABLE WINDS PRESENT. CLOUDS WILL INCREASE
EARLY SATURDAY...AHEAD OF A POWERFUL PACIFIC STORM SYSTEM
ANTICIPATED TO AFFECT THE REGION FROM SATURDAY AFTERNOON THROUGH
SUNDAY AFTERNOON. WINTER WEATHER HIGHLIGHTS HAVE BEEN ISSUED DURING
THIS TIME...FOCUSING MOSTLY ON HIGHER ELEVATIONS...DUE TO
SIGNIFICANT SNOW ACCUMULATIONS EXPECTED. AS THE SURFACE COLD FRONT
MOVES THROUGH THE REGION DURING SATURDAY EVENING...THE SNOW
POTENTIAL WILL BE FOCUSED OVER NORTHWEST MONTANA...SHIFTING
SOUTHWARD TO THE CLEARWATER AND BITTERROOT RANGES BY EARLY SUNDAY.
MOST HIGH AND LOW ELEVATION LOCATIONS WILL EXPERIENCE A BIT OF
SNOW AS THE COLD FRONT PASSES...HOWEVER THE WARM NATURE OF THIS
SYSTEM WILL KEEP ACCUMULATING SNOW ABOVE 3500 FEET. BY SUNDAY
AFTERNOON...PRECIPITATION WILL BECOME SHOWERY...WITH PERIODIC
SNOW SHOWERS OVER HIGH TERRAIN.
SUNDAY NIGHT THROUGH FRIDAY...A STRONG JET STREAM COMING INTO THE
PACIFIC NORTHWEST IS EXPECTED TO DOMINATE THE NORTHERN ROCKIES
WEATHER INTO MIDWEEK. THIS WILL RESULT IN MOUNTAIN SNOW AND VALLEY
SHOWERS. TEMPERATURES EARLY IN THE WEEK WILL BE A LITTLE BELOW
NORMAL WITH VALLEYS REACHING THE 40S IN THE AFTERNOON. LATER IN THE
WEEK HOWEVER...COMPUTER MODEL TRENDS POINT TO MUCH MILDER AND DRIER
AIR MOVING IN.
&&
.AVIATION...
HIGH PRESSURE WILL BE THE DOMINANT FEATURE PRESENT DURING THE NEXT
24 HOURS. HIGH CLOUDS ARE ANTICIPATED TO INCREASE OVER
TIME...HOWEVER CEILINGS WILL REMAIN WELL ABOVE THE MOUNTAINOUS
TERRAIN. SURFACE WINDS WILL BE VERY WEAK DURING THIS TIME AS WELL.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER WEATHER ADVISORY FROM 9 PM SATURDAY TO 9 PM MDT SUNDAY
FOR BITTERROOT/SAPPHIRE MOUNTAINS.
WINTER WEATHER ADVISORY FROM 3 PM SATURDAY TO 3 PM MDT SUNDAY
FOR KOOTENAI/CABINET REGION-LOWER CLARK FORK REGION.
ID...WINTER WEATHER ADVISORY FROM 8 PM SATURDAY TO 8 PM PDT SUNDAY
FOR NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER
MOUNTAINS.
&&
$$
SHORT TERM...ZUMPFE
LONG TERM....SIGLER
AVIATION...ZUMPFE
000
FXUS65 KMSO 131018 CCA
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
410 AM MDT FRI MAR 13 2009
.DISCUSSION...PATCHY FREEZING FOG IS POSSIBLE THIS MORNING IN THE
VALLEYS OF NORTHWEST MONTANA AND NORTH CENTRAL IDAHO. HIGH CLOUD
COVER ASSOCIATED WITH A WEATHER DISTURBANCE IN CANADA HAS SLOWED
THE RISE OF RELATIVE HUMIDITY VALUES EARLY THIS MORNING...BUT
FULL SATURATION IS EXPECTED BY DAYBREAK. AN UPPER LEVEL RIDGE OF
HIGH PRESSURE WILL CONTINUE A WARMING AND DRYING TREND TODAY WITH
TEMPERATURES FORECASTED SLIGHTLY BELOW SEASONAL NORMALS.
A MOIST PACIFIC LOW PRESSURE SYSTEM CAPABLE OF PRODUCING LIGHT TO
MODERATE SNOW ACCUMULATIONS WILL IMPACT THE NORTHERN ROCKIES SATURDAY
THROUGH SUNDAY. A WEAK DISTURBANCE AHEAD OF THE MAIN LOW WILL BRING
SHOWERS TO NORTHWEST MONTANA SATURDAY MORNING. THE FULL ONSLAUGHT
OF PRECIPITATION WILL OCCUR LATER SATURDAY AS THE UPPER LEVEL LOW
MOVES INTO THE PACIFIC NORTHWEST. SNOW LEVELS WILL BE ABOVE MOST
VALLEY FLOORS AT THE ONSET OF PRECIPITATION. AS SNOW LEVELS LOWER
SATURDAY EVENING...PRECIPITATION WILL TRANSITION TO ALL SNOW WITH
LITTLE TO NO ACCUMULATION IN MOST VALLEY LOCATIONS AND LIGHT TO
MODERATE ACCUMULATIONS IN THE HIGHER TERRAIN. THE HEAVIEST
ACCUMULATIONS ARE STILL ON TRACK TO OCCUR ACROSS THE CLEARWATER
MOUNTAINS AND BITTERROOT RANGE SATURDAY NIGHT AS PRECIPITATION
BECOMES ENHANCED BY GOOD OROGRAPHIC LIFT AND A STRONG JET STREAK
NOSING IN FROM THE WEST. TRAVEL OVER LOOKOUT AND LOLO PASSES IS
LIKELY TO BE IMPACTED BY ACCUMULATING SNOWS AND DETERIORATING
DRIVING CONDITIONS...PARTICULARLY SATURDAY NIGHT. A NEW
DEVELOPMENT WITH THIS SYSTEM IS THE POSSIBILITY OF STRONG AND
GUSTY SOUTHERLY WINDS WITH THE PASSAGE OF THE SURFACE COLD FRONT
SATURDAY NIGHT...PARTICULARLY IN THE HELLS CANYON/GRANGEVILLE
AREAS. THIS SYSTEM WILL BE CLOSELY MONITORED FOR POTENTIAL WINTER
HIGHLIGHTS FOR MOUNTAIN PASSES AND WINDS IN THE HELLS
CANYON/GRANGEVILLE AREA.
SUNDAY THROUGH TUESDAY...MODELS HAVE COME INTO ALIGNMENT PROMOTING MORE
PROGRESSIVE AND MOIST WESTERLY FLOW. THIS PATTERN WILL EFFECT THE MOUNTAINS
WITH OCCASIONAL SNOW SHOWERS AND SOME MODERATE ACCUMULATING SNOWS IMPACTING
LOOKOUT AND LOLO PASSES PRODUCING DIFFICULT DRIVING CONDITIONS AT TIMES.
CLOUDY SKIES AND OCCASIONAL RAIN SHOWERS WILL KEEP TEMPERATURES FROM
WARMING AS PREVIOUSLY ANTICIPATED. EXPECT HIGHS IN THE VALLEYS TO REMAIN
SLIGHTLY BELOW NORMAL TRANSLATING TO LOWER TO MID 40S THIS TIME OF YEAR.
CLOUDY SKIES AND A FEW RAIN SHOWERS FROM TIME TO TIME.
WEDNESDAY AND THURSDAY...LONGER RANGE MODELS ARE TRENDING TOWARD A
DEVELOPING RIDGE WHICH WOULD HELP TO BRING DRIER CONDITIONS AND AT
OR SLIGHTLY ABOVE NORMAL TEMPERATURES.
&&
.AVIATION...PATCHY FOG DEVELOPMENT IS POSSIBLE THIS MORNING IN SOME
VALLEY LOCATIONS ACROSS NORTHWEST MONTANA AND NORTH CENTRAL IDAHO.
ANY FOG THAT DEVELOPS SHOULD DISSIPATE BY MID-MORNING. OTHERWISE...VFR
CONDITIONS WILL PREVAIL FOR THE NEXT 24 HRS. CLOUD COVER WILL
BEGIN TO INCREASE AND LOWER FROM THE NORTHWEST BY SATURDAY MORNING
AS A MOIST PACIFIC LOW PRESSURE SYSTEM BEGINS TO IMPACT THE
NORTHERN ROCKIES.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...DEROSA
LONG TERM....RPN
AVIATION...DEROSA
000
FXUS65 KMSO 131010
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
410 AM MDT FRI MAR 13 2009
.DISCUSSION...PATCHY FREEZING FOG IS POSSIBLE THIS MORNING IN THE
VALLEYS OF NORTHWEST MONTANA AND NORTH CENTRAL IDAHO. HIGH CLOUD
COVER ASSOCIATED WITH A WEATHER DISTURBANCE IN CANADA HAS SLOWED
THE RISE OF RELATIVE HUMIDITY VALUES EARLY THIS MORNING...BUT
FULL SATURATION IS EXPECTED BY DAYBREAK. AN UPPER LEVEL RIDGE OF
HIGH PRESSURE WILL CONTINUE A WARMING AND DRYING TREND TODAY WITH
TEMPERATURES FORECASTED SLIGHTLY BELOW SEASONAL NORMALS.
A MOIST PACIFIC LOW PRESSURE SYSTEM CAPABLE OF PRODUCING LIGHT TO
MODERATE SNOW ACCUMULATIONS WILL IMPACT THE NORTHERN ROCKIES SATURDAY
THROUGH SUNDAY. A WEAK DISTURBANCE AHEAD OF THE MAIN LOW WILL BRING
SHOWERS TO NORTHWEST MONTANA SATURDAY MORNING. THE FULL ONSLAUGHT
OF PRECIPITATION WILL OCCUR LATER SATURDAY AS THE UPPER LEVEL LOW
MOVES INTO THE PACIFIC NORTHWEST. SNOW LEVELS WILL BE ABOVE MOST
VALLEY FLOORS AT THE ONSET OF PRECIPITATION. AS SNOW LEVELS LOWER
SATURDAY EVENING...PRECIPITATION WILL TRANSITION TO ALL SNOW WITH
LITTLE TO NO ACCUMULATION IN MOST VALLEY LOCATIONS AND LIGHT TO
MODERATE ACCUMULATIONS IN THE HIGHER TERRAIN. THE HEAVIEST
ACCUMULATIONS ARE STILL ON TRACK TO OCCUR ACROSS THE CLEARWATER
MOUNTAINS AND BITTERROOT RANGE SATURDAY NIGHT AS PRECIPITATION
BECOMES ENHANCED BY GOOD OROGRAPHIC LIFT AND A STRONG JET STREAK
NOSING IN FROM THE WEST. TRAVEL OVER LOOKOUT AND LOLO PASSES IS
LIKELY TO BE IMPACTED BY ACCUMULATING SNOWS AND DETERIORATING
DRIVING CONDITIONS...PARTICULARLY SATURDAY NIGHT. A NEW
DEVELOPMENT WITH THIS SYSTEM IS THE POSSIBILITY OF STRONG AND
GUSTY SOUTHERLY WINDS WITH THE PASSAGE OF THE SURFACE COLD FRONT
SATURDAY NIGHT...PARTICULARLY IN THE HELLS CANYON/GRANGEVILLE
AREAS. THIS SYSTEM WILL BE CLOSELY MONITORED FOR POTENTIAL WINTER
HIGHLIGHTS FOR MOUNTAIN PASSES AND WINDS IN THE HELLS
CANYON/GRANGEVILLE AREA.
SUNDAY THROUGH TUESDAY...MODELS HAVE COME INTO ALIGNMENT PROMOTING MORE
PROGRESSIVE AND MOIST WESTERLY FLOW. THIS PATTERN WILL EFFECT THE MOUNTAINS
WITH OCCASIONAL SNOW SHOWERS AND SOME MODERATE ACCUMULATING SNOWS IMPACTING
LOOKOUT AND LOLO PASSES PRODUCING DIFFICULT DRIVING CONDITIONS AT TIMES.
CLOUDY SKIES AND OCCASIONAL RAIN SHOWERS WILL KEEP TEMPERATURES FROM
WARMING AS PREVIOUSLY ANTICIPATED. EXPECT HIGHS IN THE VALLEYS TO REMAIN
SLIGHTLY BELOW NORMAL TRANSLATING TO LOWER TO MID 40S THIS TIME OF YEAR.
CLOUDY SKIES AND A FEW RAIN SHOWERS FROM TIME TO TIME.
WEDNESDAY AND THURSDAY...LONGER RANGE MODELS ARE TRENDING TOWARD A
DEVELOPING RIDGE WHICH WOULD HELP TO BRING DRIER CONDITIONS AND AT
OR SLIGHTLY ABOVE NORMAL TEMPERATURES.
&&
.AVIATION...PATCHY FOG DEVELOPMENT IS POSSIBLE THIS MORNING IN SOME
VALLEY LOCATIONS ACROSS NORTHWEST MONTANA AND NORTH CENTRAL IDAHO.
ANY FOG THAT DEVELOPS SHOULD DISSIPATE BY MID-MORNING. OTHERWISE...VFR
CONDITIONS WILL PREVAIL FOR THE NEXT 24 HRS. CLOUD COVER WILL
BEGIN TO INCREASE AND LOWER FROM THE NORTHWEST BY SATURDAY MORNING
AS A MOIST PACIFIC LOW PRESSURE SYSTEM BEGINS TO IMPACT THE
NORTHERN ROCKIES.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...DEROSA
LONG TERM....RPN
AVIATION...RPN
000
FXUS65 KMSO 122035
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
235 PM MDT THU MAR 12 2009
.DISCUSSION...MAIN FORECAST CONCERN TONIGHT IS POTENTIAL FOR
CONTINUED COLD VALLEY TEMPERATURES UNDER A BUILDING RIDGE AND
RELATIVELY CLEAR SKIES. SATELLITE IMAGERY AND MODELS INDICATE SOME
HIGH CLOUDS MAY MOVE OVERHEAD AT TIMES...BUT IT SHOULD NOT HAVE A
SIGNIFICANT IMPACT ON RADIATIONAL COOLING...ESPECIALLY IN THOSE
VALLEYS WITH GOOD SNOW COVER. THEREFORE...THE FORECAST WILL BE A
SLIGHT UPWARD TREND FROM LAST NIGHTS READINGS. TEMPERATURES ARE
WARMING A BIT MORE TODAY THAN YESTERDAY. WILL THUS MAINTAIN SOME
PATCHY FOG/LOW STRATUS TONIGHT IN THE VALLEYS OF NORTHWEST
MONTANA AND IDAHO`S CLEARWATER MOUNTAINS AS TODAY`S SLIGHT
SNOW MELT WILL INCREASE LOW LEVEL MOISTURE. THE UPPER RIDGE WILL
REMAIN IN PLACE...CONTINUING THE WARMING TREND.
SATURDAY THROUGH SUNDAY...A TROUGH OF LOW PRESSURE WILL SAG SOUTH
OUT OF CANADA AND CROSS THE NORTHERN ROCKIES AND BRING
LIGHT TO MODERATE SNOW ACCUMULATIONS TO THE REGION. PRECIPITATION
FROM THIS SYSTEM WILL ENTER NORTHWEST MONTANA SATURDAY MORNING AND
SPREAD EASTWARD. THE ONSET OF PRECIPITATION SHOULD BE IN THE FORM
OF VALLEY RAIN WITH MOUNTAIN SNOW THROUGH LATE SATURDAY. SNOW LEVELS
DURING THIS TIME WILL BEGIN TO LOWER WITH PRECIPITATION
TRANSITIONING TO ALL SNOW BY SUNDAY MORNING. WHILE VALLEY LOCATIONS
MAY SEE LIGHT SNOW ACCUMULATIONS...THE MOUNTAINS OF CENTRAL AND
NORTHWEST MONTANA AS WELL AS CENTRAL IDAHO WILL SEE THE GREATEST
ACCUMULATIONS. TRAVEL OVER LOOKOUT AND LOLO PASSES WILL LIKELY BE
IMPACTED BY ACCUMULATING SNOWS AND DETERIORATING DRIVING
CONDITIONS...PARTICULARLY ON SATURDAY NIGHT. ITS IMPORTANT TO NOTE
THAT CONFIDENCE WITH THIS SYSTEM LIES WITH THE PERSISTENCE OF
PRECIPITATION SEEN IN PAST MODEL RUNS OVER THESE
LOCATIONS...THOUGH TEMPERATURES AND SNOW LEVELS WILL HAVE AN
EFFECT ON THE FINAL SNOWFALL AMOUNTS SEEN. AS A RESULT...NO
HIGHLIGHTS HAVE BEEN ISSUED AS OF YET FOR THIS WEEKEND...THOUGH
WINTER HIGHLIGHTS FOR THE MOUNTAIN PASSES MAY NEED TO BE CONSIDERED
IN THE NEAR FUTURE.
MONDAY THROUGH WEDNESDAY...MODEL INCONSISTENCIES CONTINUE IN THE
LONG RANGE. BOTH THE GFS AND ECMWF TREND TOWARDS A MORE ACTIVE
SOLUTION BUT THE GFS IS MUCH MORE ROBUST WITH A PATTERN CHANGE ON
MONDAY. THE ECMWF TRIES TO KEEP US IN A WESTERLY TO NORTHWESTERLY
FLOW WITH EMBEDDED SHORTWAVES MOVING THROUGH THE AREA WHILE THE
GFS BRINGS A STRONG COLD FRONT THROUGH ACTING AS A FORCING
MECHANISM FOR MODERATE SNOWFALL. WITH THE LACK OF UNCERTAINTY...TRENDED
SLIGHTLY ABOVE CLIMATOLOGY FOR PRECIPITATION THROUGH THE FIRST
HALF OF NEXT WEEK AND STARTED TO TREND DOWN HIGH TEMPERATURES WITH
THE LIKELIHOOD OF ADDED CLOUD COVER.
&&
.AVIATION...STRONG INVERSIONS WILL DEVELOP AGAIN TONIGHT UNDER
RELATIVELY CLEAR SKIES. THIS COULD RESULT IN PATCHY VALLEY FOG AND
OR STRATUS WITHIN THE LOWEST TWO THOUSAND FEET FRIDAY
MORNING...PARTICULARLY IN NORTHWEST MONTANA AND NORTHERN IDAHO
WHERE SNOW MELT HAS INCREASED LOW LEVEL MOISTURE.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...WHITMORE/ALLEGRETTO
LONG TERM....LOEFFELBEIN
AVIATION...WHITMORE
000
FXUS65 KMSO 120952
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
352 AM MDT THU MAR 12 2009
.DISCUSSION...A WEAK DISTURBANCE IN CANADA TODAY WILL PUSH SCATTERED
HIGH CLOUDS THROUGH NORTHWEST MONTANA...OTHERWISE MOSTLY CLEAR
SKIES CAN BE EXPECTED. FOG WAS REMOVED FROM VALLEY LOCATIONS IN
EXTREME NORTHWEST MONTANA AND NORTH CENTRAL IDAHO FOR THIS MORNING
AS TEMPERATURE DEWPOINT SPREADS ARE TOO HIGH TO BE CONDUCIVE FOR
FOG DEVELOPMENT. WARMER TEMPERATURES AND MOSTLY CLEAR SKIES TODAY
WILL AID IN MELTING SOME OF THE VALLEY SNOW. THE INCREASE IN LOW
LEVEL MOISTURE COMBINED WITH STRONG RADIATIONAL COOLING TONIGHT
WILL ENHANCE THE FORMATION OF PATCHY FREEZING FOG IN THE VALLEYS
OF NORTHWEST MONTANA AND NORTH CENTRAL IDAHO BY FRIDAY MORNING.
CLOUD COVER WILL INCREASE FROM THE NORTHWEST THROUGH FRIDAY AS A
PACIFIC LOW PRESSURE SYSTEM BEGINS TO PUSH ONSHORE. PRECIPITATION
FROM THIS SYSTEM WILL ENTER NORTHWEST MONTANA SATURDAY MORNING AND
SPREAD EASTWARD. THE ONSET OF PRECIPITATION SHOULD BE IN THE FORM
OF VALLEY RAIN WITH MOUNTAIN SNOW AND WILL THEN TRANSITION TO ALL
SNOW BY SATURDAY NIGHT. THE HEAVIEST SNOWFALL IS EXPECTED SATURDAY
NIGHT AS SNOW PRODUCTION IS ENHANCED BY OROGRAPHIC LIFT AND UPPER
LEVEL JET SUPPORT. TRAVEL OVER LOOKOUT AND LOLO PASSES WILL LIKELY
BE IMPACTED BY ACCUMULATING SNOWS AND DETERIORATING DRIVING
CONDITIONS...ESPECIALLY SATURDAY NIGHT. WINTER HIGHLIGHTS MAY NEED
TO BE ISSUED FOR THIS SYSTEM. PLEASE REFER TO WWW.WEATHER.GOV/MISSOULA
FOR FURTHER UPDATES.
SUNDAY AND SUNDAY NIGHT...SOME MOUNTAIN SNOW SHOWERS WILL CONTINUE
ALONG AND BEHIND THE EXITING SHORT WAVE. TEMPERATURES ARE GOING TO
BE WARM ENOUGH FOR THE VALLEY RAINFALL WITH SNOW CONFINED TO THE MOUNTAINS.
SHOWERS ARE EXPECTED TO BEGIN TO DECREASE IN COVERAGE SUNDAY EVENING
AND NIGHT.
MONDAY THROUGH WEDNESDAY...LONGER RANGE MODELS AGREE ON WARMER CONDITIONS
NEXT WEEK TO ABOVE NORMAL READINGS BY MIDWEEK. BUT THEIR SOLUTIONS DIVERGE
WITH PRECIPITATION CHANCES . THE GFS BRINGS IN MORE OF A WET SOUTHWESTERLY
FLOW WITH OTHER MODELS INDICATING A STRONGER AND DRIER RIDGE
SOLUTION THUS KEPT PRECIP CHANCES AT CLIMATOLOGY.
&&
.AVIATION...A RIDGE OF HIGH PRESSURE WILL DOMINATE THE WEATHER
PICTURE THROUGH FRIDAY. CLEAR SKIES AND LIGHT WINDS WILL PRODUCE VFR
CONDITIONS AT ALL TERMINALS.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&
$$
SHORT TERM...DEROSA
LONG TERM....RPN
AVIATION...RPN
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