949
FXUS65 KBOI 120908
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
308 AM MDT FRI SEP 12 2025
SHORT TERM...TODAY THROUGH SUNDAY NIGHT
THE UPPER-LEVEL LOW
HAS ELONGATED OVER THE NORTHERN ROCKIES THIS MORNING, EXTENDING
FROM SOUTHEAST OREGON INTO NORTH-CENTRAL MONTANA. THIS FEATURE
IS MAINTAINING ISOLATED SHOWERS AND THUNDERSTORMS, MAINLY ACROSS
BAKER COUNTY AND THE WEST-CENTRAL IDAHO MOUNTAINS THIS MORNING.
THE LOW WILL REMAIN OVER THE REGION TODAY WITH SUFFICIENT
MOISTURE TO SUPPORT ADDITIONAL SHOWERS AND THUNDERSTORMS THIS
AFTERNOON. CONVECTION WILL INITIATE OVER HIGHER TERRAIN, WITH A
FEW STORMS DRIFTING INTO THE LOWER VALLEYS BY EVENING. STORMS
MAY PRODUCE HEAVY RAIN AND SMALL HAIL. PRECIPITATION CHANCES
WILL DIMINISH TONIGHT WITH THE LOSS OF DAYTIME HEATING.
AN UPPER-LEVEL RIDGE WILL BRIEFLY BUILD OVER THE AREA SATURDAY,
BRINGING A BREAK FROM PRECIPITATION AND ALLOWING TEMPERATURES
TO REBOUND TO NEAR NORMAL.
LATEST GUIDANCE TRENDS FASTER AND STRONGER WITH THE NEXT LOW
PRESSURE SYSTEM EXPECTED TO MOVE THROUGH ON SUNDAY. WHILE SOME
TIMING DIFFERENCES REMAIN, CONDITIONS APPEAR FAVORABLE FOR
THUNDERSTORM DEVELOPMENT (30–50 PERCENT CHANCE) AS THE TROUGH
PASSES DURING PEAK HEATING. PRECIPITABLE WATER VALUES
APPROACHING THE 85TH PERCENTILE, ALONG WITH MODEST SHEAR AND
INSTABILITY, WILL SUPPORT A RISK FOR HEAVY RAIN, SMALL HAIL, AND
GUSTY OUTFLOW WINDS.
LONG TERM...MONDAY THROUGH FRIDAY
SHOWER CHANCES DIMINISH
MONDAY AS AN UPPER LEVEL TROUGH MOVES EAST OF THE AREA.
TEMPERATURES ARE EXPECTED TO BE 5-10 DEGREES BELOW NORMAL MONDAY
AND TUESDAY BEHIND THE FRONT. BY WEDNESDAY, UPPER LEVEL RIDGING
SHOULD BRING WARMER TEMPERATURES WITHIN A FEW DEGREES OF
NORMAL. HOWEVER, FORECAST CONFIDENCE DECREASES BY THURSDAY AND
FRIDAY WITH MODELS SPLIT BETWEEN ANOTHER TROUGH MOVING INTO THE
PACIFIC NORTHWEST, RESULTING IN SLIGHTLY COOLER TEMPERATURES, OR
THE UPPER LEVEL RIDGE HANGING ON AND BRINGING CONTINUED WARMER
AND DRY CONDITIONS.
AVIATION
AREAS OF FOG ARE EXPECTED TO FORM IN THE MOUNTAIN
VALLEY LOCATIONS BY EARLY FRIDAY MORNING WITH REDUCED VISIBILITY
AT KBKE, KBNO AND KMYL THROUGH 16Z. SCATTERED SHOWERS AND
THUNDERSTORMS, WITH BRIEF MVFR AND IFR CONDITIONS WILL DEVELOP
IN THE AFTERNOON ACROSS THE BAKER VALLEY AND IN THE BOISE AND
WEST CENTRAL MOUNTAINS OF IDAHO LATE SATURDAY AFTERNOON WITH
HEAVY RAIN, SMALL HAIL, AND GUSTS TO 35 KT. SURFACE WINDS:
MAINLY SW-NW 5-15 KT. WINDS ALOFT AT 10KFT MSL: SE-SW 5-15 KT.
KBOI...VFR. SCATTERED MID LEVEL CLOUDS. SURFACE WINDS: NW 5-10 KT.
WEEKEND OUTLOOK.. DRIER CONDITIONS WILL RETURN SATURDAY WITH VFR
CONDITIONS EXPECTED. EXPECT EARLY MORNING FOG IN MOUNTAIN VALLEYS.
THERE IS ABOUT A 30 PERCENT CHANCE OF SHOWERS AND THUNDERSTORMS ON
SUNDAY AFTERNOON. SURFACE WINDS MAINLY SW-NW 5-15 KT.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
SHORT TERM...JDS
LONG TERM....JB
AVIATION.....JB
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