Snow Advisory 32, NWS Missoula, MT

000 
WWUS45 KMSO 200819
WSWMSO

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE MISSOULA MT
219 AM MDT SAT OCT 20 2007

.A CONSIDERABLE AMOUNT OF MOIST...UNSTABLE PACIFIC AIR WILL
CONTINUE TO MOVE THROUGH NORTH-CENTRAL IDAHO AND WESTERN MONTANA
THROUGH LATE THIS MORNING. STRONG WESTERLY WINDS ALOFT WILL HELP
ENHANCE PRECIPITATION AS IT IS FORCED OVER THE MOUNTAINOUS
TERRAIN...ESPECIALLY OVER THE SOUTHERN CLEARWATER AND BITTERROOT
MOUNTAINS. SNOWFALL ACCUMULATIONS WILL BEGIN TO TAPER OFF LATER
THIS MORNING AS TEMPERATURES RISE TO BE ABOVE FREEZING. 

IDZ006-009-MTZ006-201500-
/O.CON.KMSO.SN.Y.0032.000000T0000Z-071020T1500Z/
SOUTHERN CLEARWATER MOUNTAINS-WESTERN LEMHI COUNTY-
BITTERROOT/SAPPHIRE MOUNTAINS-
219 AM MDT SAT OCT 20 2007 /119 AM PDT SAT OCT 20 2007/

...SNOW ADVISORY REMAINS IN EFFECT UNTIL 9 AM MDT /8 AM PDT/ THIS
MORNING ABOVE 4500 FEET...

TOTAL SNOW ACCUMULATIONS OF 2 TO 5 INCHES...LOCALLY UP TO
6 INCHES ARE EXPECTED ABOVE 4500 FEET BY MID-MORNING. LOLO PASS
AND THE MCGRUDER CORRIDOR WILL BE AMONG THE AREAS IMPACTED BY
THIS EVENT.

A SNOW ADVISORY MEANS THAT PERIODS OF SNOW WILL CAUSE PRIMARILY
TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW COVERED ROADS AND
LIMITED VISIBILITIES...AND USE CAUTION WHILE DRIVING.

$$

000 
WWUS45 KMSO 201153
WSWMSO

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE MISSOULA MT
553 AM MDT SAT OCT 20 2007

IDZ006-MTZ006-201300-
/O.CAN.KMSO.SN.Y.0032.000000T0000Z-071020T1500Z/
/O.NEW.KMSO.SN.Y.0033.071021T0000Z-071021T1200Z/
SOUTHERN CLEARWATER MOUNTAINS-BITTERROOT/SAPPHIRE MOUNTAINS-
553 AM MDT SAT OCT 20 2007 /453 AM PDT SAT OCT 20 2007/

...SNOW ADVISORY IN EFFECT FROM 6 PM MDT /5 PM PDT/ THIS EVENING
TO 6 AM MDT /5 AM PDT/ SUNDAY ABOVE 4000 FEET...
...SNOW ADVISORY IS CANCELLED ABOVE 4500 FEET FOR THIS MORNING...

THE NATIONAL WEATHER SERVICE IN MISSOULA HAS ISSUED A SNOW
ADVISORY ABOVE 4000 FEET...WHICH IS IN EFFECT FROM 6 PM MDT /5 PM
PDT/ THIS EVENING TO 6 AM MDT /5 AM PDT/ SUNDAY. THE SNOW
ADVISORY ABOVE 4500 FEET FOR THIS MORNING HAS BEEN CANCELED.

2 TO 5 INCHES OF NEW SNOWFALL ACCUMULATIONS ARE EXPECTED THIS
EVENING THROUGH EARLY SUNDAY MORNING AT ELEVATIONS ABOVE 4000 FEET.
AREAS IMPACTED BY THIS EVENT INCLUDE NORTHERN IDAHO COUNTY BETWEEN
ELK CITY AND THE CLEARWATER COUNTY LINE AND LOLO PASS. THE
BITTERROOT MOUNTAINS NORTH OF HAMILTON WILL ALSO BE IMPACTED BY
THIS EVENT.

A SNOW ADVISORY MEANS THAT PERIODS OF SNOW WILL CAUSE PRIMARILY
TRAVEL DIFFICULTIES. BE PREPARED FOR SNOW COVERED ROADS AND
LIMITED VISIBILITIES...AND USE CAUTION WHILE DRIVING.

$$

IDZ009-201300-
/O.CAN.KMSO.SN.Y.0032.000000T0000Z-071020T1500Z/
WESTERN LEMHI COUNTY-
553 AM MDT SAT OCT 20 2007

...SNOW ADVISORY IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN MISSOULA HAS CANCELED THE SNOW
ADVISORY. 

$$

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE MISSOULA MT
320 PM MDT FRI OCT 19 2007

.DISCUSSION...

RAIN SHOWERS WILL CONTINUE THROUGH THE EVENING AS A PACIFIC STORM
CONTINUES TO AFFECT THE NORTHWEST. ON SATELLITE A BRIEF BREAK IN
THE CLOUDS OVER WASHINGTON CAN BE SEEN MOVING INTO IDAHO AND
EXTREME NORTHWEST MONTANA. THIS AREA SHOULD BRING A BREAK TO THE
RAIN AND SNOW LATE THIS EVENING...BUT RAIN AND SNOW WILL RETURN TO
THE FORECAST BY LATE TONIGHT AS SNOW LEVELS DROP BELOW 5000 FT.
WITH THIS IN MIND SOME FLAKES OF SNOW MAY BE SEEN IN THE VALLEYS
BUT NO ACCUMULATION IS EXPECTED BELOW 5000 FT. SO ONLY THE HIGHER
TERRAIN WILL SEE ANY SIGNIFICANT SNOWFALL AMOUNTS.

THE PRESSURE GRADIENT WILL TIGHTEN AGAIN ON SATURDAY BRINING WINDS
UP TO 15 MPH IN THE VALLEYS DURING THE AFTERNOON. HIGHS WILL BE
COOLER THAN FRIDAY AND SNOW LEVELS WILL DROP TO NEAR 4000 FT IN
MANY LOCATIONS. A FEW FLAKES OF SNOW MAY BE SEEN IN THE VALLEYS
BUT ANY ACCUMULATION IS NOT LIKELY. AS COLDER AIR MOVES IN ALOFT
THE ATMOSPHERE BECOMES MORE UNSTABLE ALLOWING FOR SOME MORE
INTENSE SHOWERS TO DEVELOP SATURDAY NIGHT. SOME HEAVIER BANDS OF
RAIN AND SNOW MAY SET UP OVER PARTS OF NORTH CENTRAL IDAHO AND
WEST CENTRAL MONTANA UNDER THIS INSTABILITY.

SUNDAY THROUGH FRIDAY...SHOWERS WILL LINGER SUNDAY IN A MOIST AND
STILL RELATIVELY UNSTABLE NORTHWEST FLOW.  WE WILL THEN
TRANSITION INTO A VALLEY INVERSION AND FOG PATTERN WITH STRONG
HIGH PRESSURE BUILDING OVERHEAD.  THE MOUNTAINS WILL WARM NICELY
MONDAY THROUGH WEDNESDAY WHILE DAILY INCREASES IN THE VALLEYS WILL
BE MORE SLUGGISH WITH STABLE COOL AIR IN PLACE.  MOST VALLEYS
WILL ALSO SEE AREAS OF LATE NIGHT AND MORNING FOG THROUGH MID WEEK.

THE NEXT SYSTEM IS EXPECTED TO FLATTEN THE RIDGE AND THEN CROSS
THE NORTHERN ROCKIES THROUGH THE LATTER HALF OF THE WEEK.  RIGHT
NOW THIS LOOKS LIKE A FAIRLY QUICK SYSTEM WITH A BRIEF PRECIPITATION
EPISODE.  BUT IT ALSO LOOKS LIKE THERE IS POTENTIAL FOR SOME COLDER
AIR TO SPILL IN FROM THE EAST AS A MUCH COOLER AIR MASS
DROPS INTO CENTRAL MONTANA.

&&

.AVIATION...IMPROVING CONDITIONS EXPECTED OVERNIGHT AS LOW
PRESSURE TROUGH MOVES OUT OF THE AREA. WINDS ARE EXPECTED TO
DECREASE...PRECIPITATION IS EXPECTED TO BECOME MORE SHOWERY...AND CEILINGS
SHOULD RISE THROUGH THE NIGHT.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...LAKE WIND ADVISORY FOR FLATHEAD LAKE THROUGH 8 PM MDT.
ID...NONE.

&&

SHORT TERM...LOEFFELBEIN
LONG TERM....WHITMORE
AVIATION...STEGEMILLER

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MISSOULA MT
256 PM MDT FRI OCT 19 2007

IDZ005-006-009-010-MTZ006-007-043-201200-
NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS-
WESTERN LEMHI COUNTY-EASTERN LEMHI COUNTY-
BITTERROOT/SAPPHIRE MOUNTAINS-BUTTE/BLACKFOOT REGION-
POTOMAC/SEELEY LAKE REGION-
256 PM MDT FRI OCT 19 2007 /156 PM PDT FRI OCT 19 2007/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTH CENTRAL
IDAHO AND WEST CENTRAL MONTANA.

.DAY ONE...TONIGHT AND SATURDAY

THE PASSING COLD FRONT AND INCOMING UPPER TROUGH WILL COMBINE TO
MAINTAIN WIDESPREAD SHOWERS OVER MUCH OF THE NORTHERN ROCKIES
TONIGHT AND SATURDAY. WHILE THE VALLEYS MAY SEE SOME SNOW MIXED
WITH THE RAIN...ACCUMULATING SNOW WILL BE CONFINED TO THE
MOUNTAINS. MOST AREAS WILL ONLY SEE LIGHT AMOUNTS...BUT ELEVATIONS
ABOVE 7000 FEET COULD SEE 5 TO 10 INCHES WITH LOCALLY HIGHER
AMOUNTS THROUGH LATE SATURDAY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH THURSDAY

MORNING FOG VALLEY WILL BE THE MAIN CONCERN THROUGH MUCH OF THE
COMING WEEK AS HIGH PRESSURE BUILDS OVER THE REGION. THE FOG WILL BE
LOCALLY DENSE AT TIMES.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.