588 
FXUS65 KMSO 271014
AFDMSO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
414 AM MDT SAT MAR 27 2010

.DISCUSSION...A STRATUS DECK ASSOCIATED WITH A MID-LEVEL
CIRCULATION LAST EVENING HAS PERSISTED OVER THE NORTHERN ROCKIES
INTO EARLY THIS MORNING. HIGH MOUNTAIN SHOWERS ARE POSSIBLE
THROUGH MID-MORNING WITH THIS DECK. OTHERWISE...CLOUD COVER IS
EXPECTED TO BREAK UP LATER THIS MORNING...GIVING WAY TO MOSTLY
SUNNY SKIES AS AN UPPER LEVEL RIDGE OF HIGH PRESSURE BUILDS OVER
THE REGION. ALTHOUGH TEMPERATURES ARE STARTING OFF A GOOD 10 TO 20
DEGREES ABOVE NORMAL THIS MORNING DUE TO THE CURRENT CLOUD
COVER...VERY LITTLE MIXING IS ANTICIPATED THIS AFTERNOON AS THE
ATMOSPHERE BECOMES MORE STABLE UNDER THE RIDGE. THIS SHOULD HINDER
HIGH TEMPERATURES FROM REACHING THEIR MAXIMUM POTENTIAL TODAY
DESPITE THE AFTERNOON SUNSHINE.

THE UPPER LEVEL RIDGE WILL BEGIN TO BREAKDOWN ON SUNDAY...ALLOWING
CLOUDS TO INCREASE AND GRADUALLY LOWER THROUGH THE DAY. BY LATE
SUNDAY AFTERNOON...THE FIRST OF SEVERAL WEATHER DISTURBANCES WILL
PUSH INTO EXTREME NORTHWEST MONTANA...AND INTO NORTH CENTRAL IDAHO
AND WESTERN MONTANA BY SUNDAY EVENING. WEST-FACING SLOPES SHOULD
RECEIVE THE BULK OF MOISTURE AS WINDS ALOFT ARE PRIMARILY FROM THE
WEST WHICH IS AN IDEAL WEATHER PATTERN FOR OROGRAPHICALLY-
ENHANCED PRECIPITATION. SOUTHERLY SURFACE WINDS ARE ALSO EXPECTED
TO INCREASE SUNDAY AFTERNOON AS THIS DISTURBANCE MOVES INTO THE
REGION AND SHOULD PERSIST THROUGH SUNDAY NIGHT.

MONDAY AND TUESDAY...A ROBUST JET STREAM WITH A GOOD TAP OF
PACIFIC MOISTURE WILL MOVE INTO THE INTERMOUNTAIN REGION ON AN
UPPER LEVEL SOUTHWEST FLOW EARLY MONDAY. A WARM AIRMASS AHEAD OF
THE SYSTEM WILL KEEP SNOW LEVELS HIGH THROUGH MUCH OF MONDAY...BUT
AS THE JET AND AN ASSOCIATED SURFACE COLD FRONT MOVE FROM NORTH TO
SOUTH...SNOW LEVELS WILL BE FALLING AFTER MIDNIGHT MONDAY NIGHT. AT
THIS TIME...GIVEN THE FORECASTED PLACEMENT OF THE SURFACE FRONT AND
UPPER JET...THE PASSES ALONG THE MONTANA/IDAHO BORDERS LOOK TO BE
THE MAIN AREAS IMPACTED BY MODERATE SNOW ACCUMULATIONS THROUGH
TUESDAY. WITH SOME MELTING OF THE SNOW AT FIRST...THEN FREEZING
WITH SNOW STICKING TO THE ROAD SURFACES...TRAVEL IMPACTS ARE
ANTICIPATED. AT THIS TIME THE MAIN IMPACT DOES APPEAR TO BE RIGHT
AT PASS LEVELS WITH ONLY LIGHT ACCUMULATIONS ON EITHER SIDE. SNOW
TOTALS AT LOLO AND LOOKOUT PASSES ARE EXPECTED TO BE BETWEEN 5 TO
8 INCHES FROM MIDNIGHT THROUGH TUESDAY AFTERNOON. OUTSIDE OF THE
PASSES...THE WESTERN MOUNTAINS OF GLACIER NATIONAL PARK...THE
CLEARWATER MOUNTAINS OF IDAHO AND WESTERN BITTERROOT MOUNTAINS ARE
ALSO EXPECTED TO SEE ACCUMULATING SNOW. OUTDOOR ENTHUSIASTS SHOULD
BE PREPARED FOR WET AND WINTRY CONDITIONS LATE MONDAY THROUGH
TUESDAY. A WEATHER STORY HIGHLIGHTING THIS WINTRY SCENARIO WILL
REMAIN ON THE WWW.WEATHER.GOV/MISSOULA WEB PAGE HIGHLIGHTING THIS
TIMEFRAME.

WEDNESDAY THROUGH FRIDAY...THE MODELS CONTINUE TO ADVERTISE A COOL
AND SHOWERY PATTERN AS THE PACIFIC TROUGH DIGS AND MOVES INLAND BY
THE END OF THE WEEK. AT THIS TIME THE MODELS DO INDICATE THE
PRECIPITATION FOCUS WILL SHIFT SOUTH ON WEDNESDAY...BUT ENERGY
SKIRTING ALONG THE CANADIAN/MONTANA BORDER WILL KEEP SLIGHT CHANCE
POPS IN THE NORTH. MODELS ARE TRYING TO INDICATE A BRIEF DRYING
PERIOD/SHORTWAVE RIDGE DURING THE LATTER PART OF NEXT WEEK BUT ARE
DISAGREEING ON THE TIMING OF THIS FEATURE. GIVEN THE PROGRESSIVE
NATURE OF THIS PATTERN...HAVE CONTINUED THE AT TO SLIGHTLY ABOVE
CLIMATOLOGICAL POPS AND NEAR TO BELOW NORMAL TEMPERATURES UNTIL
BETTER CONSISTENCY IS ACHIEVED.


&&

.AVIATION...A PERSISTENT STRATUS DECK IS EXPECTED TO LINGER OVER
THE NORTHERN ROCKIES THROUGH LATE MORNING...WITH HIGH MOUNTAIN
SHOWERS POSSIBLE UNTIL 27/1500Z. CLOUDS WILL BEGIN TO BREAK UP
LATE THIS MORNING AS AN UPPER LEVEL RIDGE OF HIGH PRESSURE BUILDS
OVER THE REGION...HELPING TO DRY AND STABILIZE THE ATMOSPHERE.
STRONG WINDS ARE STILL POSSIBLE ALONG THE CONTINENTAL DIVIDE TODAY
AND ARE EXPECTED TO DIMINISH BY EARLY THIS EVENING AS THE HIGH
PRESSURE RIDGE FULLY STABILIZES ALL LEVELS OF THE ATMOSPHERE.  


&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...NONE.
ID...NONE.
&&

$$

SHORT TERM...DEROSA
LONG TERM....MEAD
AVIATION...DEROSA