088
FXUS65 KBOI 201734
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1134 AM MDT MON JUL 20 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- HOT TEMPERATURES THIS WEEK, HOTTEST TODAY WITH A HEAT
ADVISORY IN THE SNAKE PLAIN AND HIGH DESERT.
- ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS NEAR THE
IDAHO/NEVADA BORDER TODAY.
- SHOWERS/THUNDERSTORMS INCREASE THROUGH MIDWEEK WITH HEAVY
RAINFALL POSSIBLE ESPECIALLY ON WEDNESDAY.
- AREAS OF SMOKE THROUGH THE WEEK.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
ISSUED 314 AM MDT MON JUL 20 2026
AN UPPER LEVEL RIDGE CENTERED OVER THE SOUTHERN ROCKIES WILL
BUILD NORTH TODAY, BRINGING HOTTER TEMPERATURES TO OUR AREA.
HIGHS WILL REACH THE UPPER 90S TO 105 DEGREES IN THE LOWER
VALLEYS, AND A HEAT ADVISORY REMAINS IN EFFECT FOR MUCH OF THE
LOWER ELEVATIONS ACROSS THE SNAKE PLAIN AND HIGH DESERT.
ADDITIONALLY, LOW TEMPERATURES THIS MORNING AND AGAIN TONIGHT
WILL ONLY DIP INTO THE UPPER 60S TO LOWER 70S IN THESE
LOCATIONS, LIMITING RELIEF FROM THE HEAT. SMOKE FROM OREGON
WILDFIRES MAY PREVENT SOME LOCATIONS FROM REACHING THEIR FULL
HEATING POTENTIAL. HOWEVER, SOME IMPROVEMENT IN SMOKE IS LIKELY
THIS AFTERNOON AS THE FLOW ALOFT BECOMES SOUTHERLY. SOUTHERLY
FLOW WILL ALSO TRANSPORT MONSOONAL MOISTURE INTO OUR AREA. MID
TO HIGH CLOUDS AND VIRGA/ISOLATED SHOWERS WILL LIFT NORTH ACROSS
THE AREA THIS MORNING WITH PARTIAL CLEARING IN THE AFTERNOON.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP
NEAR THE IDAHO/NEVADA BORDER THIS AFTERNOON AND EVENING, WITH
GUSTS TO 40 MPH POSSIBLE. OUTSIDE OF STORMS, BREEZY CONDITIONS
WILL DEVELOP LATE TODAY WITH GUSTS 15-30 MPH, LOCALLY UP TO 40
MPH IN EASTERN OREGON THIS EVENING.
MOISTURE WILL CONTINUE TO INCREASE TUESDAY WITH SHOWER/STORM
POTENTIAL EXPANDING ACROSS HIGHER ELEVATIONS. BY WEDNESDAY,
PRECIPITABLE WATER VALUES WILL RISE TO AROUND 1.25 INCHES,
ABOVE THE 95TH PERCENTILE. AN EMBEDDED SHORTWAVE TROUGH WILL
INTERACT WITH THIS MOISTURE, INCREASING SHOWER AND THUNDERSTORM
COVERAGE, ESPECIALLY ACROSS EASTERN AREAS WHERE PRECIPITATION
CHANCES WILL REACH 30-70%. THE HIGHER TERRAIN ACROSS SOUTHEAST
OREGON AND FAR SOUTHWEST IDAHO WILL SEE A 20-40% CHANCE OF
PRECIPITATION WITH A LESS THAN 20% CHANCE IN THE LOWER VALLEYS.
WITH DEEP MOISTURE IN PLACE AND SLOW EXPECTED STORM MOTION,
THUNDERSTORMS WILL BE CAPABLE OF HEAVY RAIN AND FLASH FLOODING,
ESPECIALLY OVER BURN SCARS AND STEEP TERRAIN.
TEMPERATURES TUESDAY AND WEDNESDAY WILL BE A FEW DEGREES LOWER
DUE TO THE INCREASING MOISTURE, BUT IT WILL STILL BE HOT.
WINDS WILL BE LOCALLY BREEZY EACH AFTERNOON. WITH SOUTHERLY FLOW
ALOFT, SMOKE SHOULD IMPROVE EACH AFTERNOON, BUT NORTHWEST
SURFACE WINDS MAY TRANSPORT SMOKE BACK INTO THE AREA EACH NIGHT.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED 314 AM MDT MON JUL 20 2026
THE PATTERN WILL SHIFT ONCE AGAIN DURING THE EXTENDED. ON
THURSDAY, AN UPPER LEVEL TROUGH OFF THE PACIFIC NORTHWEST COAST
WILL BEGIN TO DEEPEN, TURNING THE FLOW ALOFT SOUTHWESTERLY. THIS
WILL PUSH MONSOONAL MOISTURE TO THE EAST AND USHER IN A MUCH
DRIER AIRMASS. SHOWER/STORM CHANCES WILL DECREASE THROUGH THE
END OF THE WEEK, AND BY SUNDAY WILL BE LESS THAN 20% IN ALL
AREAS. SOUTHWEST FLOW WILL KEEP TEMPERATURES HOT, WITH LOWER
VALLEY HIGHS IN THE UPPER 90S TO AROUND 100 DEGREES. THE TROUGH
WILL BRING BREEZY CONDITIONS EACH DAY WITH GUSTS 15-30 MPH.
SMOKE MAY IMPACT THE AREA THROUGH THE PERIOD, ESPECIALLY ACROSS
SOUTHEAST OREGON.
AVIATION /18Z MONDAY THROUGH TUESDAY/
ISSUED 1133 AM MDT MON JUL 20 2026
GENERALLY VFR. AREAS MVFR VISIBILITY DUE TO WILDFIRE SMOKE.
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS NEAR THE
IDAHO/NEVADA BORDER FROM 20/21Z THROUGH 21/06Z...THUNDERSTORM
OUTFLOW GUSTS TO 35 KT. HIGH DENSITY ALTITUDE DURING AFTERNOON
HOURS DUE TO HEAT. SURFACE WINDS: NW-N 10-15 KT WITH LOCALIZED
GUSTS TO 25 KT FROM 20/20Z THROUGH 21/06Z. WINDS ALOFT AT 10KFT
MSL: VARIABLE 5-10 KT.
KBOI...GENERALLY VFR. OCCASIONAL MVFR VISIBILITY DUE TO WILDFIRE
SMOKE. HIGH DENSITY ALTITUDE DURING AFTERNOON HOURS DUE TO HEAT.
SURFACE WINDS: NW 10-15 KT WITH GUSTS TO 25 KT FROM 20/20Z UNTIL
21/03Z.
BOI WATCHES/WARNINGS/ADVISORIES
ID...AIR QUALITY ALERT UNTIL 3 PM MDT WEDNESDAY FOR IDZ011-012-014-
033.
HEAT ADVISORY UNTIL 9 PM MDT THIS EVENING FOR IDZ012-014>016-
030-033.
OR...HEAT ADVISORY UNTIL 9 PM MDT /8 PM PDT/ THIS EVENING FOR
ORZ063-064.
AIR QUALITY ALERT UNTIL NOON PDT TODAY FOR ORZ061-062.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....LC
SHORT TERM...ST
LONG TERM....ST
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