642
FXUS65 KMSO 022017
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
217 PM MDT TUE JUN 2 2026
DISCUSSION
KEY MESSAGES:
- RIVERS, STREAMS, AND CREEKS CONTINUE TO RUN HIGH ACROSS
NORTHWEST MONTANA FROM PROLONGED RAIN AND ONGOING SNOWMELT.
- SHOWERS AND THUNDERSTORMS RETURN LATE WEDNESDAY INTO THURSDAY
MORNING.
- ACTIVE WEATHER PATTERN THIS WEEKEND INTO NEXT WEEK.
THE LOW PRESSURE SYSTEM THAT BROUGHT WIDESPREAD HEAVY RAIN TO
WESTERN MONTANA THE PAST SEVERAL DAYS IS FINALLY MOVING OFF TO THE
EAST. LATEST SATELLITE AND RADAR IMAGES SHOW THE HEAVIEST
PRECIPITATION EAST OF THE CONTINENTAL DIVIDE. WHILE NORTHWEST
MONTANA IS STARTING TO SEE SOME BREAKS IN THE CLOUDS WITH ONLY A
FEW ISOLATED SHOWERS PRODUCING A HUNDREDTH OR TWO OF RAINFALL PER
HOUR. RIVERS AND STREAMS CONTINUE TO BE RUNNING HIGH ACROSS
NORTHWEST MONTANA SO AREAL FLOOD WATCHES AND WARNINGS REMAIN IN
EFFECT FOR AREAS ALONG THE MISSION AND SWAN MOUNTAIN RANGES UP
INTO GLACIER NATIONAL PARK.
THE NEXT DISTURBANCE IS EXPECTED TO PUSH ACROSS THE NORTHERN
ROCKIES LATE WEDNESDAY INTO THURSDAY MORNING. THIS FEATURE WILL
CAUSE SCATTERED TO NUMEROUS SHOWERS AND ISOLATED THUNDERSTORMS
STARTING OFF IN NORTH CENTRAL IDAHO BY WEDNESDAY AFTERNOON AND
THEN WESTERN MONTANA DURING THE EVENING. THE SHOWER ACTIVITY IS
EXPECTED TO LINGER OVER THE AREA THROUGHOUT THE OVERNIGHT HOURS
AND DIMINISH THURSDAY AFTERNOON. THE BULK OF THE VALLEYS SHOULD
RECEIVE BETWEEN 0.05 TO 0.15 INCHES OF PRECIPITATION WITH THE
HIGHER TERRAIN GETTING 0.25 TO 1.0 INCH OF RAIN. A FEW AREAS COULD
RECEIVE HIGHER AMOUNTS UNDER HEAVIER THUNDERSTORM ACTIVITY. SNOW
LEVELS APPEAR TO BE HOVERING AROUND 9000 FEET DURING THE PASSAGE
FROM THIS DISTURBANCE.
THE UPPER LEVEL FLOW BECOMES SOUTHWESTERLY ON SATURDAY AS A TROUGH
OF LOW PRESSURE MOVES INTO THE PACIFIC NORTHWEST. THIS FLOW
PATTERN WILL ALLOW TEMPERATURES TO BE NEAR TO ABOVE SEASONAL
AVERAGE WITH THE POTENTIAL OF SHOWERS AND THUNDERSTORM
DEVELOPMENT, ESPECIALLY ACROSS LEMHI COUNTY INTO SOUTHWEST
MONTANA. THE LONG TERM MODELS ARE STILL STRUGGLING ON HOW THIS LOW
PRESSURE SYSTEM WILL IMPACT THE NORTHERN ROCKIES AND DEVELOP
DURING THE FIRST PART OF NEXT WEEK. THE FAR MAJORITY OF THE MODELS
DO SHOW PART OF THE TROUGH MAKING ITS WAY THROUGH THE NORTHERN
ROCKIES ON SUNDAY CAUSING COOLER TEMPERATURES ALONG WITH SCATTERED
SHOWER ACTIVITY.
AVIATION
THE UPPER LEVEL LOW THAT HAS BROUGHT SENSIBLE WEATHER
TO THE AREA FOR THE PAST WEEK IS FINALLY PULLING OFF TO THE EAST.
IN ITS WAKE RESIDUAL CLOUDS ARE FOUND WITH A FEW LINGERING SHOWERS
GENERALLY OVER THE DIVIDE AND GENERALLY OVER I-90 FROM CLINTON
EASTWARDS. FOR THE TERMINALS, EXPECT MID-CLOUD THROUGH THIS
EVENING WITH EITHER VARIABLE OR NORTHERLY WINDS LESS THAN 15
KNOTS. SKY COVER WILL BEGIN TO BREAK UP TONIGHT AS A TRANSIENT
RIDGE MOVES INTO THE REGION. WITH THE RECENT MOISTURE, THERE COULD
BE PATCHY FOG THAT DEVELOPS, POSSIBLY AT KGPI, KMSO AND KBTM. ON
WEDNESDAY, A SHORTWAVE WILL BRING SHOWERS AND A FEW THUNDERSTORMS
ACROSS NORTH-CENTRAL IDAHO BEFORE 6 PM MDT, THEN INTO WESTERN
MONTANA THEREAFTER. IMPACTS FROM STORMS INCLUDE LIGHTNING, GUSTY
WINDS TO 35 KNOTS, HEAVY RAIN AND SMALL HAIL.
MSO WATCHES/WARNINGS/ADVISORIES
MT...FLOOD WATCH UNTIL 6 PM MDT THIS EVENING FOR WEST GLACIER REGION.
ID...NONE.
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