091
FXUS65 KMSO 042009
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
109 PM MST TUE NOV 4 2025
DISCUSSION
KEY MESSAGES:
- WET WEATHER TO DECREASE BY THIS EVENING ACROSS WESTERN MONTANA.
- SNOW SHOWERS WITH BREEZY WINDS ARE POSSIBLE WEDNESDAY NIGHT
ABOVE 5000 FEET MSL. HIGH ELEVATION-BACKCOUNTRY ROADS COULD
BECOME HAZARDOUS AT TIMES.
- A SECOND SYSTEM ON FRIDAY WILL BRING MOUNTAIN SNOW AND GUSTY
WESTERLY WINDS ABOVE 4500 FEET.
- HIGH PRESSURE BUILDS THIS WEEKEND...POSSIBLE FOG AND LOW CLOUDS
BY SUNDAY MORNING.
EXPECT RESIDUAL LIGHT RAIN SHOWERS TO DISSIPATE BY THIS EVENING.
AN UPPER-LEVEL WARM FRONT WILL PASS OVERHEAD LATER TONIGHT AND
COULD BRING BRIEF PERIOD OF LIGHT PRECIPITATION. THE COOLER AIR IS
HOLDING ON A BIT ACROSS NORTHWEST MONTANA. SNOW LEVELS COULD RANGE
BETWEEN 3000 FEET ACROSS NORTHERN LINCOLN COUNTY TO 4000 FEET
ACROSS THE REMAINDER OF NORTHWEST MONTANA. SO DON'T BE SURPRISED
TO WAKE UP WITH A DUSTING OF SNOW IN THE YAAK AREA WEDNESDAY
MORNING.
ANOTHER FRONT WILL MOVE ACROSS THE REGION WEDNESDAY AFTERNOON INTO
THE EVENING HOURS. WITH MILDER AIR MOVING IN ALOFT, THE SNOW
LEVELS WILL CONTINUE TO RISE TO 6000-7000 FEET MSL MOST AREAS,
EXCEPT ACROSS NORTHWEST MONTANA WHERE THE LEVELS COULD BE AS LOW
AS 5500 FEET WEDNESDAY AFTERNOON. SNOW LEVELS FALL TO 5000 TO 6000
FEET BY THURSDAY MORNING. SNOW SHOWERS COULD PRODUCE PERIODS OF
SLUSH ON THE ROADS AT MARIAS PASS. THIS WILL BE A WET PATTERN WITH
THE MOUNTAINS RECEIVING 0.25 TO 0.75 INCHES OF PRECIPITATION
THROUGH THURSDAY MORNING, SOME LOCATIONS COULD GET UP TO 1.00",
SPECIFICALLY THE UPSLOPE AREAS ALONG THE IDAHO/MONTANA BORDER, AND
IN THE MISSION AND SWAN RANGES. THIS COULD EQUATE TO 5 TO 10
INCHES OF WET SNOW IN THE HIGH COUNTRY ABOVE 5500 FEET. SO MAKE
SURE YOU PLAN ACCORDINGLY IF YOU ARE HUNTING OR RECREATING AT
THOSE ELEVATIONS. GUST WESTERLY WINDS DEVELOP ON THURSDAY, MAINLY
FELT IN THE MOUNTAINS, BUT A FEW VALLEY LOCATIONS COULD EXPERIENCE
GUSTS OVER 25 MPH...I.E. ALONG THE DIVIDE AND ACROSS SOUTHWEST
MONTANA. THE STRONGER GUSTS OVER 35 MPH WILL MAINLY BE OVER THE
DIVIDE (> 80%).
THE TROUGH PASSAGE ON FRIDAY LOOKS VERY SIMILAR TO WEDNESDAY'S
SYSTEM, THOUGH SNOW LEVELS WILL TREND SLIGHTLY LOWER (AROUND 4500
FEET). PRECIPITATION FORECASTS ARE SIMILAR WITH 0.25 TO 0.75
INCHES IN THE MOUNTAINS. AGAIN, WESTERLY WINDS WILL DEVELOP AND
COULD GUST WELL OVER 40 MPH IN THE MOUNTAINS AND HIGH VALLEYS
ALONG AND WEST OF THE DIVIDE.
A BUILDING RIDGE CONTINUES TO BE EXPECTED OVER THE WEEKEND.
LEFTOVER CLOUD COVER AND A FEW SHOWERS ARE POSSIBLE SATURDAY
MORNING ACROSS NORTHWEST MONTANA, BUT EXPECT PARTIAL CLEARING.
AREAS OF LOW CLOUDS AND FOG COULD DEVELOP BY SUNDAY MORNING IN THE
VALLEYS, AS STABLE HIGH PRESSURE DEVELOPS(AROUND 1027 MILLIBARS).
THERE COULD BE A FAIR AMOUNT OF HIGH CLOUDS THAT MOVE OVER THE
REGION SUNDAY, WHICH COULD DIM THE SUN A BIT.
THE NEXT QUESTION IS, HOW LONG WILL THIS RIDGE LAST? AND WILL IT
BE A "DIRTY" OR UNSETTLED TYPE RIDGE WITH MOISTURE MOVING AROUND
IT? LOOKING UPSTREAM, THE PACIFIC JET IS QUITE ACTIVE AND VERY
"BUCKLED". THERE CONTINUES TO BE PLENTY OF TROPICAL ACTIVITY IN
THE WESTERN EQUATORIAL PACIFIC, INCLUDING A TYPHOON THAT COULD
CONTINUE TO EXCITE AND EXTEND THE EAST ASIAN JET/PACIFIC JET NOV.
11-13. THIS COULD HAVE A DOMINO EFFECT AND IN A SENSE, SHIFT OUR
RECENT "BUCKLED" PATTERN EASTWARDS, PLACING LOWER
HEIGHTS/TROUGHS OVER THE WESTERN U.S. ENSEMBLES ARE DEPICTING
REMNANTS OF A PLUME OF MOISTURE AIMED AT SOUTHWESTERN BRITISH
COLUMBIA TO SHIFT OVER US BY MONDAY THE 10TH AND 11TH. THE CAVEAT
WITH THIS PROPOSED PATTERN IS THAT THE MODELS PREDICTED THIS
SIMILAR TYPE OF PATTERN FOR YESTERDAY (NOV 3), BUT A SUBTLE
SHORTWAVE KEPT THE RIDGE FLATTER THEREFORE KEEPING IT MUCH COLDER
OVER NORTHWEST MONTANA LEADING TO THE SNOWFALL IN THE VALLEYS! IF
WE ARE ABLE TO GET A PATTERN CHANGE LATER IN THE SECOND WEEK OF
NOVEMBER, THEN TROUGHS COULD DIG A LITTLE FURTHER SOUTH, PLACING
US IN THE COLDER SIDE OF THE JET...MEANS A COOLER AND ACTIVE
PATTERN FOR US...MORE MOUNTAIN SNOW! THE ENSEMBLES AND EVEN
EXTENDED MODELS ARE HINTING AT THIS.
AVIATION
SHOWERS WILL BE ON THE DECREASE BY THIS
EVENING(TUESDAY EVENING). WITH THE RESIDUAL MOISTURE,
REDEVELOPMENT OF LOW STRATUS OR FOG IS POSSIBLE INTO THE
OVERNIGHT. A WEAK WARM FRONT WILL BRING MID-LEVEL CLOUD AND LIGHT
PRECIPITATION LATER TONIGHT INTO WEDNESDAY MORNING. THIS FEATURE
COULD HELP TO IMPROVE ANY FOG OR STRATUS TEMPORARILY, BUT THEN COULD
REDEVELOP THEREAFTER. AN OCCLUDED FRONT WILL MOVE ACROSS THE
REGION WEDNESDAY AFTERNOON AND CAUSE SNOW LEVELS TO GRADUALLY FALL
TO AROUND 5500 FEET MSL BY WEDNESDAY NIGHT. MOUNTAIN OBSCURATION
CAN BE EXPECTED AT TIMES THROUGH THURSDAY MORNING.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page