913
FXUS65 KBOI 102027
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
227 PM MDT FRI JUL 10 2026
KEY MESSAGES
- HEAT ADVISORY TODAY AND SATURDAY FOR LOWER ELEVATIONS OF
SOUTHWEST IDAHO AND SOUTHEAST OREGON, BUT CONTINUING THROUGH
MONDAY EVENING IN SOUTH-CENTRAL IDAHO.
- BREEZY AFTERNOON WINDS THROUGH THE WEEKEND.
- SHOWER AND THUNDERSTORM CHANCES RETURN LATE MONDAY THROUGH
TUESDAY NIGHT WITH THE ARRIVAL OF MONSOON MOISTURE.
SHORT TERM /THROUGH SUNDAY NIGHT/
WE ARE MAINTAINING THE CURRENT HEAT ADVISORY FOR THE TREASURE
VALLEY, UPPER WEISER RIVER VALLEY, AND SOUTHWEST IDAHO HIGHLANDS
THROUGH SATURDAY EVENING, BUT EXTENDING IT THROUGH MONDAY
EVENING IN THE WESTERN MAGIC VALLEY AND SOUTHERN TWIN FALLS
COUNTY. THOSE AREAS WILL REMAIN CLOSEST TO THE MAIN UPPER
LEVEL HIGH PRESSURE DOME CENTERED OVER THE NORTHERN PLAINS AND
COVERING HALF THE US. SOUTHWEST FLOW ALOFT OVER THE WESTERN US
WILL DRAW MONSOON MOISTURE TOWARD OUR CWA BEGINNING SATURDAY,
WITH INCREASING CLOUDS IN OREGON BEGINNING SATURDAY NIGHT AND IN
IDAHO BEGINNING SUNDAY, EVENTUALLY LEADING TO HIGH-BASED
THUNDERSTORMS IN ALL SOUTHERN ZONES MONDAY EVENING. THE CLOUDS
WILL KEEP NIGHTTIME TEMPS WARM AND PROVIDE ONLY LIMITED RELIEF
FROM THE DAYTIME HEAT. AFTERNOON WINDS WILL GUST TO 30 MPH IN
BAKER AND HARNEY COUNTIES, AND UP TO 20 MPH ELSEWHERE.
LONG TERM /MONDAY THROUGH FRIDAY/
THE UPPER-LEVEL RIDGE CENTERED OVER THE NORTHERN GREAT PLAINS WILL
BE QUITE STRONG MONDAY AND TUESDAY, DRIVING A MONSOONAL PUSH OF
MID/HIGH LEVEL MOISTURE AND PRECIPITABLE WATER VALUES NORTHWARD
INTO THE REGION. AS A RESULT, SHOWER AND THUNDERSTORM CHANCES
WILL INCREASE STARTING LATE MONDAY, FAVORING HIGHER TERRAIN.
INITIAL CONVECTION WILL LEAN DRIER AND BE OUTFLOW DOMINANT FROM
PRECEDING DRY LOW-LEVELS, BUT SHOULD SOON BECOME HEAVIER RAIN
PRODUCERS TUESDAY INTO WEDNESDAY AS PWAT VALUES REACH 1.00"+
(I.E., ABOVE 95TH PERCENTILE RELATIVE TO CLIMATOLOGY) AND LOW-
LEVELS MOISTEN. SHOWER/THUNDERSTORM CHANCES WILL EXPAND TO MOST
AREAS BY TUESDAY. CONCERN WILL GRADUALLY SHIFT FROM FIRE DANGER
MONDAY AND TUESDAY (DUE TO LIGHTNING ON DRY FUELS), TO FLASH-
FLOOD POTENTIAL BY TUESDAY AND WEDNESDAY (ESPECIALLY OVER BURN
SCARS). MEANWHILE, A BROAD PACIFIC TROUGH IS FORECAST TO MOVE
SOUTHWARD ALONG THE WEST COAST MONDAY AND TUESDAY, BUT MODELS
DISAGREE ON WHEN TO BRING THE TROUGH ONSHORE AND PUSH MONSOON
MOISTURE TOWARD THE EAST. THE TROUGH EVOLUTION WILL DETERMINE
WHETHER SHOWERS AND THUNDERSTORMS CONTINUE THROUGH THE REST OF
THE WEEK/NEXT WEEKEND, OR GRADUALLY DECREASE AROUND MID- WEEK.
OVERALL, SOUTHERLY FLOW IS EXPECTED TO PERSIST THROUGH FRIDAY
AND SUPPORT HOT TEMPERATURES AREA-WIDE.
AVIATION /18Z FRIDAY THROUGH SATURDAY/
ISSUED 1130 AM MDT FRI JUL 10 2026
VFR. AREAS OF REDUCED VISIBILITY FROM WILDFIRE SMOKE. HIGH DENSITY
ALTITUDE DUE TO HEAT. ISOLATED CONVECTION OVER CENTRAL ID MOUNTAINS
AND SOUTH-CENTRAL ID THIS AFTERNOON. SURFACE WINDS: LIGHT AND
VARIABLE. BECOMING SW-W 10-15 KT WITH GUSTS TO 20-30 KT OVER SE
OREGON AND HIGHER TERRAIN OF SW IDAHO IN THE AFTERNOON. WINDS
ALOFT AT 10KFT MSL: SW 5-15 KT.
KBOI...VFR. HIGH DENSITY ALTITUDE DUE TO HEAT. VISIBILITY REDUCED
AT TIMES BY WILDFIRE SMOKE IN FOOTHILLS NE OF KBOI. SURFACE WINDS:
SE-S 5-10 KT, BECOMING NW-N 5-10 KT LATE AFTERNOON / EARLY EVENING.
WEEKEND OUTLOOK...VFR. AREAS OF REDUCED VISIBILITY FROM WILDFIRE
SMOKE. HIGH DENSITY ALTITUDE DUE TO HEAT, ESPECIALLY SATURDAY.
SURFACE WINDS: SW-NW 5-15 KT SAT/SUN. AFTERNOON GUSTS TO 20-30
KT ACROSS SE OREGON AND (MAINLY) THE HIGHER TERRAIN OF SW IDAHO.
BOI WATCHES/WARNINGS/ADVISORIES
ID...HEAT ADVISORY UNTIL 9 PM MDT SATURDAY FOR IDZ012-014-015-033.
HEAT ADVISORY UNTIL 9 PM MDT MONDAY FOR IDZ016-030.
OR...HEAT ADVISORY UNTIL 9 PM MDT /8 PM PDT/ SATURDAY FOR ORZ064.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
SHORT TERM...LC
LONG TERM....CH
AVIATION.....CH
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