899
FXUS65 KBOI 200914
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
314 AM MDT MON JUL 20 2026
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/
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/
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 /06Z MONDAY THROUGH TUESDAY/
ISSUED 1205 AM MDT MON JUL 20 2026
GENERALLY VFR. WILDFIRE SMOKE ACROSS THE AREA RESULTING IN LOCALIZED
MVFR/IFR VISIBILITIES, MAINLY IN E-OREGON AND NEAR KEUL. SOME
IMPROVEMENT BY MON/PM. ISOLATED SHOWERS/VIRGA LIFTING NORTH THROUGH
SE OREGON OVERNIGHT. AFTERNOON HIGH DENSITY ALTITUDE THROUGH THE
WEEK. SURFACE WINDS: VARIABLE UP TO 8 KT OVERNIGHT. THEN SW-NW 10-15
KT WITH LOCALIZED GUSTS TO AROUND 20 KT MON/PM. WINDS ALOFT AT 10KFT
MSL: VARIABLE 5-15 KT.
KBOI...VFR. VISIBILITY REDUCTIONS DUE TO WILDFIRE SMOKE, ALTHOUGH
VFR EXPECTED TO PREVAIL. AFTERNOON HIGH DENSITY ALTITUDE THIS WEEK
DUE TO HEAT. SURFACE WINDS: LIGHT AND VARIABLE OVERNIGHT, THEN NW 10-
15 KT WITH GUSTS TO 20-25 KT MON/PM.
BOI WATCHES/WARNINGS/ADVISORIES
ID...HEAT ADVISORY FROM NOON TODAY TO 9 PM MDT THIS EVENING FOR
IDZ012-014>016-030-033.
OR...HEAT ADVISORY FROM NOON MDT /11 AM PDT/ TODAY TO 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
SHORT TERM...ST
LONG TERM....ST
AVIATION.....NF
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