High Wind in Montana, February 15 to 16, 2007

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
840 PM MST THU FEB 15 2007

.UPDATE...STEADY AND HEAVY SNOW HAS ENDED IN EXTREME NORTHWEST
MONTANA. WILL CANCEL THE HEAVY SNOW WARNING FOR THIS AREA. THIS IS
THE ONLY UPDATE NECESSARY FOR NOW.

&&

.AVIATION...WARM AND MOIST SOUTHWEST FLOW THIS EVENING WILL
PRODUCE WIDESPREAD MOUNTAIN SNOW AND VALLEY RAIN...OBSCURING THE
MOUNTAINS AND PASSES. VISIBILITIES AND CEILINGS WILL ALSO LOWER AT
THE TERMINALS OF WESTERN MONTANA AND NORTH CENTRAL IDAHO. WINDS
WILL INCREASE AS A COLD FRONT MOVES ACROSS THE REGION LATER TONIGHT...SEE
APPROPRIATE TAFS AND TWEBS.

&&

.PREV DISCUSSION... /ISSUED 244 PM MST THU FEB 15 2007/

DISCUSSION...A WESTERLY FLOW ALOFT WILL BE PUMPING CONSIDERABLE
PACIFIC MOISTURE INTO THE INTER-MOUNTAIN REGION TONIGHT. THE
SOUTHERLY FLOW NEAR THE SURFACE WAS AIDING IN THE WARMING OF THE
LOWER ATMOSPHERE AND CAUSING SNOW LEVELS TO RISE THIS AFTERNOON.
THUS...HEAVY SNOWFALL WILL BE CONFINED TO ELEVATED TERRAIN. AN
ASSOCIATED COLD FRONT WILL PASS THROUGH THE AREA LATER TONIGHT AND
WILL BE ACCOMPANIED WITH STRONG WESTERLY WINDS...FUELED BY STRONG
WINDS ALOFT AND SURFACE PRESSURE GRADIENT. THIS ELEMENT OF WIND
HAS PROMPTED THE ISSUANCE OF WINTER STORM WARNINGS IN LIEU OF
HEAVY SNOW WARNING IN PORTIONS OF WESTERN MONTANA.

FRIDAY AND FRIDAY NIGHT...CONDITIONS FAVOR SNOW BANDING DURING
THE MORNING HOURS AS THE MOISTURE FIELD BECOMES MORE SHALLOW IN
RESPONSE TO SUBSIDENCE WARMING AND DRYING OF THE MID/HIGH LEVELS
OF THE ATMOSPHERE. MOISTURE AND INSTABILITY REMAINS AT THE LOWER
LEVELS WITH A STRONG WIND FLOW THROUGH THE LAYER. THE UPPER FLOW
WILL BECOME NORTHWESTERLY IN THE WAKE OF THE FRONTAL SYSTEM WITH A
VERY STRONG JET (+150KTS) DRAPED OVER THE AREA. OROGRAPHIC
ENHANCEMENT TO MOUNTAIN SNOW SHOWERS WILL DEFINITELY BE IN PLAY.
IT WILL ALSO BE A WINDY DAY ACROSS MUCH OF THE AREA ON FRIDAY.
ALTHOUGH TEMPERATURES ALOFT WILL BE CONSIDERABLY COOLER...STEEP
LAPSE RATES TO THE SURFACE WILL LIKELY RESULT IN WARMISH TEMPS IN THE
VALLEYS. ON FRIDAY NIGHT...MORE RIDGING ALOFT WILL STABILIZE THE
LOWER ATMOSPHERE WITH SHOWERS DIMINISHING.

HIGH PRESSURE OVER THE NORTHERN ROCKIES SATURDAY WILL BRING A
BRIEF RESPITE FROM THE WIDESPREAD PRECIPITATION SEEN OVER THE LAST
FEW DAYS. LATEST MODEL RUNS HAVE WEAKENED THIS RIDGE
SLIGHTLY...ALLOWING MOISTURE TO PROPAGATE THROUGH RIDGE AXIS
ACROSS NORTHWEST MONTANA. THEREFORE...EXPECT LIGHT MOUNTAIN SNOW
SHOWERS AND SOME CLOUD COVER TO PERSIST. FOG DOES NOT LOOK VERY LIKELY IN
THIS PATTERN AS CLOUD COVER AND WINDS DUE TO A TIGHTENING PRESSURE
GRADIENT SHOULD INHIBIT ITS FORMATION.

SUNDAY AFTERNOON...THE HIGH PRESSURE RIDGE WEAKENS AS AN UPPER
LEVEL TROUGH AND ASSOCIATED FRONTAL BOUNDARY APPROACH THE REGION.
FRONTAL BOUNDARY IS EXPECTED TO SAG SOUTHEASTWARD ACROSS WESTERN
MONTANA AND NORTH CENTRAL IDAHO THROUGH SUNDAY NIGHT...BRINGING
ANOTHER ROUND OF WIDESPREAD PRECIPITATION. TEMPERATURES WILL DROP
BEHIND THIS FEATURE TO MORE SEASONABLE NORMS.

A PROGRESSIVE PATTERN WILL CONTINUE THROUGH THE REST OF THE WEEK...
WITH MOISTURE AND STRONG WESTERLY FLOW ALOFT MAINTAINING MOIST
CONDITIONS...ESPECIALLY IN THE HIGHER TERRAIN.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...WINTER STORM WARNING UNTIL 5 AM MST FRIDAY ABOVE 4500 FEET
     FOR LOWER CLARK FORK REGION-POTOMAC/SEELEY LAKE REGION-WEST
     GLACIER REGION.

     WINTER STORM WARNING UNTIL 5 AM MST FRIDAY ABOVE 5500 FEET FOR
     BITTERROOT/SAPPHIRE MOUNTAINS.

ID...WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR LOWER HELLS
     CANYON/SALMON RIVER REGION-OROFINO/GRANGEVILLE REGION.

     HEAVY SNOW WARNING UNTIL 4 AM PST FRIDAY ABOVE 5500 FEET FOR
     NORTHERN CLEARWATER MOUNTAINS-SOUTHERN CLEARWATER MOUNTAINS.

&&

SHORT TERM...RPN
LONG TERM....MSJ
AVIATION...RPN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE MISSOULA MT
902 PM MST THU FEB 15 2007

MTZ003-005-007-161615-
FLATHEAD/MISSION VALLEYS-MISSOULA/BITTERROOT VALLEYS-
BUTTE/BLACKFOOT REGION-
902 PM MST THU FEB 15 2007

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

.DAY ONE...TONIGHT

A COLD FRONT WILL PUSH ACROSS WESTERN MONTANA TONIGHT. WINDS WILL
INCREASE TO 20 TO 30 MPH WITH SOME GUSTS REACHING 45 MPH WITH THE
FRONTS PASSAGE AND SHORTLY BEHIND IT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

ANOTHER COLD FRONT WILL MOVE ACROSS WESTERN MONTANA SUNDAY BRINGING
ANOTHER GOOD CHANCE FOR RAIN AND SNOW.

.SPOTTER INFORMATION STATEMENT...

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

IDZ009-010-161615-
WESTERN LEMHI COUNTY-EASTERN LEMHI COUNTY-
902 PM MST THU FEB 15 2007

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

.DAY ONE...TONIGHT

A COLD FRONT WILL PUSH ACROSS LEMHI COUNTY IDAHO TONIGHT. WINDS WILL
INCREASE TO 20 TO 30 MPH WITH SOME GUSTS REACHING 45 MPH WITH THE
FRONTS PASSAGE AND SHORTLY BEHIND IT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

ANOTHER COLD FRONT WILL MOVE ACROSS LEMHI COUNTY IDAHO SUNDAY INTO SUNDAY
NIGHT BRINGING ANOTHER GOOD CHANCE FOR RAIN AND SNOW.

.SPOTTER INFORMATION STATEMENT...

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

MTZ001-161615-
KOOTENAI/CABINET REGION-
902 PM MST THU FEB 15 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST
MONTANA.

.DAY ONE...TONIGHT

MOUNTAIN SNOWS WILL BEGIN TO TAPER OFF AFTER MIDNIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

AN UNSETTLED WEATHER PATTERN IS EXPECTED SUNDAY THROUGH WEDNESDAY.
MOUNTAIN SNOWS MAY PRODUCE TRAVEL DIFFICULTIES.

.SPOTTER INFORMATION STATEMENT...

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