045
FXUS65 KMSO 180816
AFDMSO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MISSOULA MT
216 AM MDT THU JUN 18 2026
DISCUSSION
KEY MESSAGES:
- A RIDGE BUILDING OVER THE REGION TODAY WILL CAUSE TEMPERATURES
TO WARM.
- A SURGE OF MONSOONAL MOISTURE FRIDAY NIGHT INTO SATURDAY MAY
BRING THUNDERSTORMS CAPABLE OF HEAVY RAIN AND GUSTY WINDS TO
SOUTHWEST MONTANA AND LEMHI COUNTY.
FORECASTS ARE HIGHLY CONFIDENT THAT A STRONG RIDGE OF HIGH
PRESSURE WILL BUILD ACROSS THE NORTHERN ROCKIES TOMORROW. THIS
WEATHER PATTERN WILL BRING QUICK WARMING, PUSHING TOMORROW
AFTERNOON TEMPERATURES INTO THE MID-TO-UPPER 80S ACROSS WESTERN
MONTANA AND INTO THE MID-90S IN THE LOWER VALLEYS OF CENTRAL
IDAHO. COMPUTER MODELS SHOW A SLIGHT CHANCE FOR SCATTERED SHOWERS
TO DEVELOP ACROSS WESTERN MONTANA THIS AFTERNOON, WITH A FEW
THUNDERSTORMS POSSIBLE ALONG THE CONTINENTAL DIVIDE IN NORTHWEST
MONTANA.
BY LATE TOMORROW NIGHT, AN UNUSUALLY STRONG SURGE OF MONSOONAL
MOISTURE WILL MOVE NORTH FROM THE GREAT BASIN, COMBINING WITH A
WEAK UPPER-LEVEL SHORTWAVE. THIS COMBINED MOISTURE AND ENERGY WILL
BRING WIDESPREAD SHOWERS AND THUNDERSTORMS, PRIMARILY IMPACTING
LEMHI COUNTY AND SOUTHWEST MONTANA THROUGH SATURDAY. THE MAIN
IMPACTS FROM THESE STORMS WILL BE HEAVY RAIN AND SUDDEN, STRONG
WIND GUSTS. UNCERTAINTY REMAINS REGARDING HOW FAR NORTH THESE
STORMS WILL TRAVEL, THOUGH SOME MODELS SHOW THE RAIN AND STORMS
MOVING AS FAR NORTH AS MISSOULA. ONCE THIS SYSTEM CLEARS OUT, A
HIGH-PRESSURE RIDGE WILL QUICKLY REBUILD OVER THE REGION, STARTING
ANOTHER PERIOD OF HOT, DRY WEATHER.
AVIATION
A RIDGE CENTERED OVER THE U.S. WEST COAST WILL EXTEND
ITS INFLUENCE FURTHER EAST INTO WESTERN MONTANA TODAY. SINCE THE
REGION IS ON THE EASTERN EDGE OF THE RIDGE, EXPECT SOME GUSTY
NORTHWEST WINDS IN THE AFTERNOON WITH GUSTS UP TO 20KT. OTHERWISE,
VFR CONDITIONS PREVAIL.
MSO WATCHES/WARNINGS/ADVISORIES
MT...NONE.
ID...NONE.
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