105
FXUS65 KBOI 131603
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1003 AM MDT SAT SEP 13 2025
DISCUSSION
AREAS OF FOG ARE PERSISTING IN SOME MOUNTAIN VALLEY AREAS THIS
MORNING, INCLUDING THE MCCALL AREA. EXPECTING THIS TO BURN OFF
BY LATE MORNING. OTHERWISE, UPPER RIDGING OVERHEAD WILL LEAD TO
A QUIETER DAY WEATHER-WISE, DESPITE ANOMALOUSLY HIGH MOISTURE
LEVELS OBSERVED, WITH ONLY ISOLATED THUNDERSTORM ACTIVITY
CONFINED TO THE CENTRAL IDAHO MOUNTAINS. CLOUDS INCREASE FROM
THE WEST LATER TONIGHT AHEAD OF AN APPROACHING OFFSHORE UPPER-
LEVEL TROUGH.
AVIATION
PATCHY FOG MOSTLY DISSIPATED. ISOLATED SHOWERS AND
THUNDERSTORMS REDEVELOPING OVER THE CENTRAL ID MOUNTAINS THIS
AFTERNOON. GENERALLY VFR THROUGH THE TAF PERIOD THOUGH. SURFACE
WINDS: VARIABLE LESS THAN 10 KT, BECOMING W-NW 5-15 KT THIS
AFTERNOON. WINDS ALOFT AT 10KFT MSL: W 5-15 KT.
KBOI...VFR. LIGHT SE WINDS THIS MORNING, BECOMING NW 5-10 KT
THIS AFTERNOON.
SUNDAY OUTLOOK...A TROUGH AND COLD FRONT WILL BRING SCATTERED
SHOWERS AND THUNDERSTORMS TO THE AREA IN THE AFTERNOON AND EVENING.
STORMS MAY BRING MVFR/IFR CONDITIONS, MOUNTAIN OBSCURATION, GUSTY
OUTFLOW WINDS UP TO 45 KT, SMALL HAIL, AND HEAVY RAIN. SURFACE WINDS
SE-SW 5-15 KT IN THE MORNING, BECOMING W-NW 10-20 KT IN THE
AFTERNOON AND EVENING BEHIND THE COLD FRONT.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH MONDAY NIGHT...AN UPPER-LEVEL RIDGE
WILL BRIEFLY BUILD OVER THE AREA SATURDAY, BRINGING MOSTLY
SUNNY SKIES AND ALLOWING TEMPERATURES TO REBOUND TO NEAR NORMAL.
THE ONLY EXCEPTION WILL BE A SLIGHT CHANCE OF SHOWERS AND
THUNDERSTORMS OVER THE CENTRAL IDAHO MOUNTAINS THIS AFTERNOON.
A POTENT, NEGATIVELY TILTED TROUGH WILL MOVE ACROSS THE REGION
SUNDAY FROM SOUTHWEST TO NORTHEAST, BRINGING A 30 TO 60 PERCENT
CHANCE OF THUNDERSTORMS. CONVECTIVE PARAMETERS SUPPORT THE
POTENTIAL FOR STRONGER STORMS, WITH BULK SHEAR NEAR 30 KTS AND
MUCAPE VALUES OF 300 TO 800 J/KG. THIS ENVIRONMENT WILL BE
SUFFICIENT TO PRODUCE GUSTY OUTFLOW WINDS UP TO 50 MPH, ALONG
WITH SMALL HAIL SUNDAY AFTERNOON AND EVENING AS STORMS DEVELOP
WITH THE COLD FRONT. HEAVY RAINFALL WILL ALSO BE A CONCERN, WITH
PRECIPITABLE WATER VALUES IN THE 80TH TO 85TH PERCENTILE.
RECENT CAM GUIDANCE INDICATES THAT STRONGER STORMS COULD QUICKLY
PRODUCE 0.50 TO 1.50 INCHES OF RAIN, RAISING FLASH FLOOD
CONCERNS NEAR BURN SCARS.
THE TROUGH EXITS LATE SUNDAY NIGHT, WITH PATCHY FOG POSSIBLE IN
MOUNTAIN VALLEYS AND AREAS THAT RECEIVE EXCESSIVE RAINFALL. AN
UPPER-LEVEL RIDGE WILL REBUILD ON MONDAY, THOUGH TEMPERATURES
WILL REMAIN ABOUT 10 DEGREES BELOW NORMAL.
LONG TERM...TUESDAY THROUGH SATURDAY...A RIDGE WILL BUILD OVER
THE AREA TUESDAY, BRINGING MOSTLY SUNNY SKIES AND A RETURN TO
NEAR-NORMAL TEMPERATURES. BY WEDNESDAY, HIGHS ARE EXPECTED TO
RISE TO AROUND 5 DEGREES ABOVE NORMAL. FORECAST CONFIDENCE
DECREASES BEYOND MIDWEEK, AS ENSEMBLE GUIDANCE IS SPLIT ON THE
EVOLUTION OF THE NEXT UPPER-LEVEL TROUGH. THE PREVAILING TREND
FAVORS A SHIFT TOWARD MORE ACTIVE NORTHWESTERLY FLOW, WHICH
WOULD SUPPORT A TRANSITION TO COOLER TEMPERATURES LATE IN THE
PERIOD.
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
DISCUSSION...JR
AVIATION.....JM
SHORT TERM...JDS
LONG TERM....JDS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page