FXUS65 KMSO 061638 CCA
AFDMSO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
1008 AM MDT SAT SEP 6 2008

.UPDATE...HAVE UPDATED MOST ELEMENTS OF THE FORECAST FOR THE
REMAINDER OF THIS MORNING AND THIS AFTERNOON.

&&

.DISCUSSION...CLEAR SKIES ACROSS NORTHWEST MONTANA THIS MORNING
HAVE CAUSED TEMPERATURES TO DIP AND THE ATMOSPHERE REACH
SATURATION. THIS HAS RESULTED IN THE FORMATION OF PATCHY FOG
WITHIN SOME OF THE DEEPER VALLEYS ACROSS NORTHWEST MONTANA. EXPECT
REDUCED VISIBILITY IN FOG TO CONTINUE THROUGH ABOUT THE NOON HOUR
BEFORE LIFTING TO A LOWER CLOUD DECK AND ULTIMATELY DISSIPATING
THIS AFTERNOON AS THE ATMOSPHERE BEGINS TO MIX AND BECOME MORE
TURBULENT.

A COMPARATIVE ANALYSIS OF THIS MORNING'S TEMPERATURES VERSUS
YESTERDAYS VALUES REVEAL THAT THE PREVIOUS FORECAST MAX
TEMPERATURES MAY BE A LITTLE TOO COOL. THUS HAVE ADJUSTED SOME
LOCATIONS...MAINLY NORTHWEST MONTANA WHERE IT IS NOW CLEAR AND
LOCATIONS IN IDAHO WHERE CLOUDS AND SHOWERS REMAIN. ALTHOUGH THESE
CLOUDS AND LIGHT SHOWERS CURRENTLY OVER CENTRAL IDAHO MAY PROVIDE
SOME LIMIT TO THE POTENTIAL HEATING TODAY...BELIEVE THAT SHORTLY
AFTER NOON THESE CLOUDS WILL DISSIPATE REVEALING MORE SUN AND
ULTIMATELY WARMER CONDITIONS.


&&

.AVIATION...CLOUDS AND A FEW SHOWERS WILL OBSCURE MOUNTAIN TOPS
TODAY AND TONIGHT ACROSS SOUTHWEST MONTANA AND CENTRAL IDAHO. SKY
CONDITIONS ARE EXPECTED TO IMPROVE TONIGHT ACROSS NORTHERN IDAHO AS
A DRIER AIR MASS WILL ACCOMPANY A WEAK RIDGE OF HIGH PRESSURE.
CLEARING OVER THE IDAHO PANHANDLE WILL PROMOTE REDEVELOPMENT OF FOG
IN THE VALLEYS EARLY SUNDAY MORNING.

&&

.PREV DISCUSSION... /ISSUED 335 AM MDT SAT SEP 6 2008/

DISCUSSION...NORTHWEST FLOW ALOFT WITH WEAK WEATHER DISTURBANCES
MOVING OVER THE NORTHERN ROCKIES WILL MAINTAIN COOL AND SHOWERY
CONDITIONS THROUGH THE WEEKEND. IN THIS WEATHER PATTERN...FORECAST
MODELS HAVE HAD A DIFFICULT TIME RESOLVING THESE WEAK IMPULSES OF
ENERGY. THEREFORE...TIMING INDIVIDUAL FEATURES BECOMES DIFFICULT
BEYOND 12 TO 24 HOURS. ONE SUCH IMPULSE IS CURRENTLY CREATING
SHOWERS ALONG THE CONTINENTAL DIVIDE INTO CENTRAL MONTANA...WITH A
SECONDARY WAVE AFFECTING PORTIONS OF NORTH CENTRAL IDAHO. MAIN
SHOWER ACTIVITY IS EXPECTED ALONG THE CONTINENTAL DIVIDE AND
ACROSS SOUTHWEST MONTANA THROUGH THE AFTERNOON HOURS. ANOTHER WAVE
IS EXPECTED LATE TONIGHT INTO SUNDAY...THOUGH DUE TO REASONS
PREVIOUSLY STATED CONFIDENCE IN STRENGTH AND TIMING IS SOMEWHAT
LOW. LOOKS LIKE MAIN FOCUS WITH THIS FEATURE WILL AGAIN BE ALONG
THE CONTINENTAL DIVIDE WITH THE BRUNT OF THE ENERGY AND MOISTURE
PASSING OVER CENTRAL MONTANA. TEMPERATURES WILL REMAIN BELOW
NORMAL AS CLOUD COVER CONTINUES TO LIMIT SURFACE HEATING.

A WEAK RIDGE OF HIGH PRESSURE WILL BEGIN TO BUILD SUNDAY
NIGHT...BRINGING A GRADUAL DECREASE IN PRECIPITATION. AS CLEARING
BEGINS FROM WEST TO EAST...FOG WILL BECOME A POSSIBILITY FOR LOW
LYING AREAS...ESPECIALLY IN NORTHWEST MONTANA AND THE FAVORED
VALLEYS OF NORTH CENTRAL IDAHO.

A BRIEF DRYING PERIOD WITH A PASSING SHORT-WAVE RIDGE MONDAY WILL
QUICKLY GIVE WAY TO AN UPPER LEVEL TROUGH OF LOW PRESSURE
DESCENDING OUT OF SOUTHWEST CANADA TUESDAY. THIS LOW PRESSURE
TROUGH WILL PROVIDE INCREASED CHANCES OF PRECIPITATION...CLOUDS
AND COOLER TEMPERATURES TO NORTHERN IDAHO AND WESTERN MONTANA
TUESDAY AND WEDNESDAY. TEMPERATURES WILL REBOUND AGAIN THURSDAY
AND FRIDAY AS A RIDGE OF HIGH PRESSURE BUILDS BACK INTO THE
REGION.

&&

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

$$

SHORT TERM...DICKERSON
LONG TERM....MSJ
AVIATION...DEROSA








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