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000
FXUS65 KMSO 240545
AFDMSO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
ISSUED BY NATIONAL WEATHER SERVICE GREAT FALLS MT
1145 PM MDT THU MAY 23 2013

...UPDATE TO AVIATION...

.UPDATE...
UPDATED FORECAST IS OUT. ONLY REAL CHANGE WAS TO INCREASE POPS TO
100 PERCENT ALONG THE DIVIDE AND LOWER TEMPS IN BIT IN THE BUTTE
AREA. SNOW IS FALLING FOR MANY AREAS ALONG THE DIVIDE...SO CURRENT
WINTER HIGHLIGHTS LOOK GOOD. BRUSDA

&&

.AVIATION...MOISTURE AND LIFT CONTINUE TO PUSH THROUGH THE AREA WITH
WIDESPREAD PRECIPITATION AND MVFR/IFR CONDITIONS FROM KSMN TO KBTM.
CONDITIONS ARE EXPECTED TO IMPROVE BY 12Z WITH PRECIPITATION ENDING
FROM SOUTH TO NORTH. AFTER 12Z...CONDITIONS SHOULD BECOME VFR AT ALL
TAF SITES. A MOIST AND UNSTABLE AIRMASS WILL REMAIN OVER THE AREA
FRIDAY RESULTING IN SCATTERED AFTERNOON AND EVENING SHOWERS. MPJ

&&

.PREV DISCUSSION... /ISSUED 300 PM MDT THU MAY 23 2013/

DISCUSSION...WESTERN MONTANA AND NORTH CENTRAL IDAHO ARE
CURRENTLY IN BETWEEN WEATHER FEATURES THIS AFTERNOON, WHICH HAS
ALLOWED US A BRIEF RESPITE FROM PRECIPITATION. THIS WILL BE SHORT
LIVED HOWEVER AS ANOTHER WAVE OF ENERGY IS EXPECTED TO ROTATE
AROUND THE LOW PRESSURE SYSTEM CURRENTLY SITTING IN THE PACIFIC
NORTHWEST. THIS WAVE HAS AN IMPRESSIVE AMOUNT OF LIFT ASSOCIATED
WITH IT AND THUS ANOTHER ROUND OF POTENTIALLY HEAVY WET SNOW IS
EXPECTED LATE THIS AFTERNOON THROUGH FRIDAY MORNING. THE LOCATIONS
WITH THE GREATEST LIKELIHOOD OF SEEING IMPACTFUL SNOW THIS EVENING
INCLUDE SOUTHWEST MONTANA (BUTTE, GEORGETOWN LAKE, ANACONDA,
MACDONALD PASS AND HOMESTAKE PASS), AND LEMHI COUNTY (LOST TRAIL
PASS, SALMON, GILMORE SUMMIT). LOCATIONS FURTHER NORTH ALONG THE
CONTINENTAL DIVIDE (WEST GLACIER, SWAN LAKE, CONDON, SEELEY LAKE)
WILL LIKELY SEE MORE SNOW DEVELOP OVERNIGHT INTO THE EARLY MORNING
HOURS. THE MAIN IMPACT FROM THIS NEXT ROUND OF SNOW WILL BE
SLUSHY/SLICK ROADWAYS, BREAKAGE OF TREE LIMBS WHICH HAVE ALREADY
BEEN WEAKENED BY TODAY`S SNOW, AND PERIODS OF VERY LOW VISIBILITY
DUE TO CONVECTIVE SHOWERS BRINGING SHORT LIVED PERIODS OF INTENSE
SNOWFALL. ADDITIONAL POWER OUTAGES ARE POSSIBLE. VARIOUS WINTER
WEATHER PRODUCTS WILL REMAIN IN EFFECT THROUGH FRIDAY MORNING.

THIS NEXT WAVE OF ENERGY WILL EXIT THE REGION TOMORROW MORNING,
BRINGING A SOMEWHAT DRIER PERIOD FOR THE MORNING. THIS WILL BE
AGAIN, SHORT-LIVED HOWEVER AS YET ANOTHER WAVE OF ENERGY ROTATES
AROUND THE LOW PRESSURE SYSTEM BRINGING ENHANCED SHOWERS ACROSS
ALL OF WESTERN MONTANA AND NORTH CENTRAL IDAHO. THE MAIN FOCUS OF
THESE SHOWERS DOES APPEAR TO BE ACROSS NORTHWEST MONTANA WHERE
ANOTHER ROUND OF SNOW SHOWERS IS POSSIBLE. FORECAST MODELS DO
INDICATE SNOW LEVELS BEGINNING TO RISE DURING THIS TIME SO
ACCUMULATING SNOW SHOULD NOT BE AS IMPACTFUL AS THE LATEST WAVES
MOVING THROUGH THE REGION.

FOR THE HOLIDAY WEEKEND IT DOES APPEAR CONDITIONS WILL MODERATE
SLIGHTLY BACK TOWARDS MORE NORMAL CONDITIONS FOR THIS TIME OF
YEAR. THE THREAT OF PRECIPITATION WILL BE ON THE DECLINE ALTHOUGH
THEIR COULD BE SOME LINGERING SHOWERS?PARTICULARLY IN THE
AFTERNOONS. TEMPERATURES WILL RISE BACK TO NEAR NORMAL FOR THIS
TIME OF YEAR.

BY MONDAY ANOTHER TROUGH OF LOW PRESSURE IS EXPECTED TO PUMP
MOISTURE AND ENERGY BACK INTO THE REGION BRINGING PRECIPITATION
BACK INTO THE FORECAST. THIS COULD TRANSLATE INTO THUNDERSTORMS
ACROSS THE REGION BY TUESDAY AND WEDNESDAY.

&&

NOTE: FLOOD WATCHES...WARNINGS AND ADVISORIES WILL NOT BE LISTED BELOW.

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING UNTIL 9 AM MDT FRIDAY BUTTE/BLACKFOOT
     REGION.

     WINTER WEATHER ADVISORY UNTIL 9 AM MDT FRIDAY
     BITTERROOT/SAPPHIRE MOUNTAINS.

     WINTER WEATHER ADVISORY UNTIL 9 AM MDT FRIDAY POTOMAC/SEELEY
     LAKE REGION...WEST GLACIER REGION.

ID...WINTER WEATHER ADVISORY UNTIL 9 AM MDT FRIDAY EASTERN
     LEMHI COUNTY.

&&

$$