Strong Wind in Idaho, January 11, 2010

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1127 AM MST MON JAN 11 2010

.UPDATE...WE HAVE ISSUED A FLOOD WARNING ALONG THE SALMON RIVER
FROM 4 MILES NORTH OF SALMON TO THE NORTH FORK AREA FOR ICE JAMS.

&&

.DISCUSSION...COLD TEMPERATURES CONTINUED IN THE SALMON RIVER
REGION FROM SALMON TO NORTH FORK THIS PAST WEEKEND INTO MONDAY MORNING.
AS A RESULT...ADDITIONAL ICE HAS DEVELOPED ALONG THE SALMON RIVER
AND PUSHED SOME OF THE RIVER FLOW OUT OF THE MAIN CHANNEL ALONG PORTIONS
OF THE RIVER.

&&

AVIATION...VERY STABLE CONDITIONS WILL CONTINUE IN MOST WESTERN
MONTANA VALLEYS TODAY WITH EITHER HAZE/SMOKE OR AREAS OF LOW
CLOUDS AND FOG PERSISTING INTO THE AFTERNOON. THE INVERSIONS
SHOULD WEAKEN SOME INTO TUESDAY MORNING. HOWEVER...GENERAL STABLE
CONDITIONS WILL CONTINUE WITH LOW LEVEL MOISTURE AND POLLUTANTS
CONTINUE TO BE TRAPPED IN MANY VALLEYS. EXPECT FOG TO IMPACT KGPI
TODAY LOWERING VISIBILITIES AND CEILINGS. A DENSE FOG ADVISORY HAS
BEEN ISSUED FOR THE MISSION AND FLATHEAD VALLEYS OF NORTHWEST
MONTANA UNTIL 2 PM MONDAY AFTERNOON...IMPACTING KGPI

&&

.HYDROLOGY...A FLOOD WARNING HAS BEEN ISSUED FOR THE SALMON RIVER
FROM ABOUT 4 MILES NORTH OF SALMON TO THE NORTH FORK AREA. SEE THE
FLOOD WARNING POSTED ON WWW.WEATHER.GOV/MISSOULA.

&&

.PREV DISCUSSION... /ISSUED 1039 AM MST MON JAN 11 2010/

UPDATE...UPDATED FORECAST TO EXTEND THE DENSE FOG ADVISORY FOR
THE FLATHEAD AND MISSION VALLEYS THROUGH EARLY AFTERNOON. ALSO
UPDATED FOR LOCAL STRONG SOUTH WINDS IN THE LOWER SALMON/HELLS
CANYON REGION OF IDAHO THROUGH TONIGHT.

DISCUSSION...THE VERY STABLE VALLEY CONDITIONS WILL CONTINUE
TODAY. IN ADDITION...HIGH CLOUDS HAVE MOVED OVER MUCH OF NORTHWEST
MONTANA AND WILL FURTHER REDUCE HEATING TODAY. AS A RESULT...THE
FOG IN THE MISSION AND FLATHEAD VALLEYS IS EXPECTED TO PERSIST
INTO THE EARLY AFTERNOON. A RELATIVELY STRONG SOUTHERLY FLOW HAS
DEVELOPED OVER THE LOWER SALMON RIVER/HELLS CANYON AREA OF IDAHO
TODAY AND MAY ACTUALLY INCREASE SOME TONIGHT. AS A RESULT...A WIND
ADVISORY HAS BEEN ISSUED.

PREV DISCUSSION... /ISSUED 407 AM MST MON JAN 11 2010/

DISCUSSION...DENSE FOG HAS DEVELOPED IN THE MISSION/FLATHEAD
VALLEYS OVERNIGHT PROMPTING A DENSE FOG ADVISORY TO BE ISSUED.
ELSEWHERE...PATCHY FOG IS EXPECTED THIS MORNING. FOG WILL BE
LIFTING LATER MORNING...POSSIBLY INTO A STRATUS DECK. CONSIDERABLE
MID/HIGH LEVEL MOISTURE WILL BE MOVING INLAND ACROSS THE PACIFIC
NORTHWEST INTO WESTERN MONTANA TODAY AND TONIGHT UNDER A
SOUTHWESTERLY FLOW ALOFT. ANY CHANCES FOR PRECIPITATION WILL BE
CONFINED TO THE FAR NORTHWEST CORNER OF MONTANA TODAY...WITH THE
IDAHO PANHANDLE GETTING INTO THE PRECIP PICTURE TONIGHT. AS
SOUTHERLY WINDS INCREASE ALOFT AND THE SURFACE PRESSURE GRADIENT
STRENGTHENS WITH TIME...SOUTHERLY WINDS WILL INCREASE IN THE
SALMON/SNAKE RIVER DRAINAGES IN IDAHO COUNTY. SOUTHERLY WINDS ARE
EXPECTED TO PICKUP IN THE CAMAS PRAIRIE AREA SOMETIME LATER
TODAY/TONIGHT...BUT BASIN INVERSIONS WILL NEED TO MIX OUT FIRST
BEFORE THESE WINDS CAN BE REALIZED. FOG/STRATUS SHOULD BECOME LESS
PROMINENT AS CLOUDS/WINDS ALOFT INCREASE OVER THE REGION TONIGHT
AND TUESDAY. CHANCE OF PRECIPITATION WILL BE INCREASING ACROSS
IDAHO AND INTO WESTERN MONTANA TUESDAY WITH THE GRADUAL MOISTENING
OF THE AIR MASS.

WEDNESDAY THROUGH SUNDAY...THE OVERALL WEATHER PATTERN DURING THIS
PERIOD IS EXPECTED TO BE RATHER PROGRESSIVE WITH A SERIES OF
PACIFIC DISTURBANCES APPROACHING THE WEST COAST. THESE
DISTURBANCES WILL BE ENCOUNTERING A RIDGE OR SPLIT FLOW PATTERN AS
THEY MOVE INLAND OVER THE INTER-MOUNTAIN REGION...EFFECTIVELY
WEAKENING THEM IN THE PROCESS. THIS IS TYPICAL OF EL NINO WINTERS
AND MAY BE THE BEST WAY TO DESCRIBE THE UPCOMING PATTERN NEXT
WEEK. THAT SAID...THERE WILL BE A FAIR AMOUNT OF MOISTURE IN THE
FORM OF CLOUDS CYCLING THROUGH THE IDAHO PANHANDLE AND MUCH OF
WESTERN MONTANA. BEST CHANCES OF PRECIPITATION WILL BE TARGETING
NORTHWEST MONTANA AND THE IDAHO PANHANDLE. CURRENT TIMING OF THE
MOST SIGNIFICANT WEATHER DISTURBANCES MOVING THROUGH THE REGION
WILL BE WEDNESDAY NIGHT/THURSDAY AND ANOTHER NEXT WEEKEND.

AVIATION...STRATUS CLOUDS WILL CONTINUE ACROSS NORTHWEST AND
AREAS OF WEST CENTRAL MONTANA AND NORTH CENTRAL IDAHO THIS
MORNING. VALLEY INVERSIONS REMAIN...BUT WILL BE WEAKENING AS
TEMPERATURES CONTINUE TO MODERATE IN THE VALLEYS. PATCHY TO AREAS
OF FOG IS EXPECTED IN SOME VALLEYS OF NORTH CENTRAL IDAHO AND
NORTHWEST MONTANA. EXPECT FOG TO IMPACT BOTH KGPI AND KMSO THIS
MORNING LOWERING VISIBILITIES AND CEILINGS. A DENSE FOG ADVISORY
HAS BEEN ISSUED FOR THE MISSION AND FLATHEAD VALLEYS OF NORTHWEST
MONTANA UNTIL 11 AM MONDAY MORNING...IMPACTING KGPI. THE LOWERED
CLOUDS WILL OBSCURE MOUNTAINS AND PASSES.

AIR STAGNATION...SURFACE BASED INVERSIONS WILL CONTINUE TO HOLD
PARTICULATES IN THE VALLEYS OF WESTERN MONTANA TODAY. HOWEVER...
COLD AIR TRAPPED IN THE WEST CENTRAL MONTANA VALLEYS SHOULD
CONTINUE TO WEAKEN ITS GRIP AS SOUTHERLY WINDS ALOFT AND CLOUDS
INCREASE DURING THE NEXT 24-36 HOURS.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...DENSE FOG ADVISORY UNTIL 2 PM MST THIS AFTERNOON FOR
     FLATHEAD/MISSION VALLEYS.

ID...WIND ADVISORY UNTIL 4 AM PST TUESDAY FOR LOWER HELLS
     CANYON/SALMON RIVER REGION.

&&

SHORT TERM...BAUCK
LONG TERM....MSJ
AVIATION...BAUCK