Wind Advisory 8, NWS Missoula, MT

249 
WWUS75 KMSO 130220
NPWMSO

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE MISSOULA MT
820 PM MDT MON APR 12 2010


IDZ010-130330-
/O.CAN.KMSO.WI.Y.0008.000000T0000Z-100413T0300Z/
EASTERN LEMHI COUNTY-
820 PM MDT MON APR 12 2010

...WIND ADVISORY IS CANCELLED...

THE NATIONAL WEATHER SERVICE IN MISSOULA HAS CANCELLED THE WIND
ADVISORY. 

WINDS HAVE DECREASED SIGNIFICANTLY AS CONVECTION HAS WEAKENED IN
THE AREA.

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
302 PM MDT MON APR 12 2010

.DISCUSSION... PRECIPITATION CONTINUES TO SPREAD ACROSS NORTHWEST
MONTANA THIS AFTERNOON WITH RAIN FALLING IN VALLEY LOCATIONS.
EASTERLY WINDS WILL REMAIN BREEZY THROUGH THIS EVENING AND SHOULD
DISSIPATE NEAR SUNSET WHEN THE GRADIENT FINALLY RELAXES. MEANWHILE
TO THE SOUTH...CONVECTIVE SHOWER ACTIVITY HAS BEGUN TO INCREASE
IN NORTH CENTRAL IDAHO. AREAS IN LEMHI COUNTY AND SOUTHWEST
MONTANA THAT SAW SOME CLEARING TODAY WILL HAVE THE BEST POTENTIAL
FOR ISOLATED THUNDERSTORM DEVELOPMENT THE REST OF THIS AFTERNOON
AND EVENING. ENHANCED LIFT FROM A JET STREAK IN THESE AREAS WILL
ALSO PROVIDE ADDITIONAL SUPPORT FOR THUNDERSTORMS.

BY LATE THIS EVENING...THE FOCUS TURNS TO A DEEPENING SURFACE LOW
PRESSURE SYSTEM OVER WYOMING WITH A MID-LEVEL CIRCULATION OVER
EASTERN ID/SOUTHWEST MT. SIGNIFICANT MOISTURE WILL WRAP AROUND
THE CLOSED LOW PRESSURE SYSTEM BRINGING THE MAIN FOCUS FOR SNOW
ACCUMULATIONS THROUGH SOUTHWEST MONTANA IN FAVORED LOCATIONS SUCH
AS GEORGETOWN LAKE. A PRESSURE GRADIENT WILL TIGHTEN AS THE SYSTEM
MATURES...WITH WIND EXPECTED TO ACCOMPANY THE SNOW. MOST OF THE
REGIONS PASSES WILL HAVE ACCUMULATING SNOW AS THE LOW PRESSURE
SYSTEM PASSES JUST EAST OF THE DIVIDE. NUMEROUS SNOW ADVISORIES
HAVE BEEN ISSUED ALONG WITH A WINTER WEATHER WARNING FOR THE
BUTTE/BLACKFOOT REGION FOR SNOW ACCUMULATIONS OF 6-10 INCHES ABOVE
5500 FEET. ALTHOUGH THE LOWER ELEVATIONS ARE NOT INCLUDED...THEY
WILL ALSO SEE ACCUMULATING SNOW AND GUSTY WINDS. SNOW WILL
CONTINUE WITH THE SYSTEM AS IT MOVES TO THE NORTH THROUGH THE
GLACIER REGION. THERE IS STILL A LITTLE UNCERTAINTY AS TO WHETHER
THE GLACIER PARK REGION WILL SEE WIDESPREAD HEAVY SNOW
ACCUMULATIONS...SO A WATCH AS BEEN ISSUED. SNOW WILL BEGIN TO
REPRIEVE FROM SOUTH TO NORTH STARTING TUESDAY EVENING AND
CONTINUING THROUGH WEDNESDAY.

WEDNESDAY NIGHT THROUGH EARLY FRIDAY THE MODELS ARE IN DECENT
AGREEMENT THAT AN UPPER LEVEL RIDGE WILL BUILD OVER NORTH CENTRAL
IDAHO AND WESTERN MONTANA FOR A DRYING TREND. THE FORECAST HAS
BEEN ADJUSTED TO SHOW MORE DRYING DURING THIS TIMEFRAME. FRIDAY
THROUGH EARLY NEXT WEEK...A PROGRESSIVE SOUTHWEST UPPER FLOW WILL
RETURN THE REGION TO UNSETTLED BUT WARM CONDITIONS.

&&

.AVIATION...STRONG AND GUSTY EAST WINDS ARE EXPECTED TO PREVAIL
THROUGH EARLY THIS EVENING ACROSS WESTERN MONTANA. MEANWHILE A
MOIST PACIFIC WEATHER SYSTEM WILL MOVE INTO THE NORTHERN ROCKIES
TONIGHT...SPREADING SHOWERS FROM SOUTH TO NORTH. THIS AFTERNOON
INTO EARLY EVENING...THE ATMOSPHERE OVER THE SOUTHERN CLEARWATERS
AND SOUTHWEST MONTANA WILL BECOME UNSTABLE ENOUGH FOR SOME
ISOLATED THUNDERSTORM DEVELOPMENT. GUSTY AND ERRATIC WINDS ARE
POSSIBLE IN THE VICINITY OF ANY THUNDERSTORMS THAT OCCUR...MAINLY
IMPACTING KMSO...KSMN AND KBTM. MOUNTAINS AND PASSES WILL BECOME
OBSCURED BY LOW CLOUDS AND SHOWERS TONIGHT THROUGH TUESDAY ACROSS
THE SOUTH.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO 6 PM MDT TUESDAY
     ABOVE 5500 FEET FOR THE BUTTE/BLACKFOOT REGION.

     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM MDT
     TUESDAY ABOVE 5000 FEET FOR THE BITTERROOT/SAPPHIRE
     MOUNTAINS.

     WINTER STORM WATCH FROM TUESDAY AFTERNOON THROUGH WEDNESDAY
     MORNING WEST GLACIER REGION.

     WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT MDT
     TUESDAY NIGHT POTOMAC/SEELEY LAKE REGION.

ID...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM MDT
     TUESDAY ABOVE 6000 FEET FOR THE EASTERN LEMHI COUNTY.

&&

KITSMILLER/
DEROSA/MEAD