991
FXUS65 KBOI 230550
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1150 PM MDT WED JUL 22 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- NUMEROUS SHOWERS AND THUNDERSTORMS TODAY ACROSS THE CENTRAL
IDAHO MOUNTAINS. THUNDERSTORMS MAY PRODUCE HEAVY RAIN,
CREATING A RISK OF FLASH FLOODING AND DEBRIS FLOWS,
ESPECIALLY OVER BURN SCARS AND STEEP TERRAIN.
- ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ELSEWHERE
TODAY AND THURSDAY, WITH BRIEF HEAVY RAIN AND GUSTY WINDS
POSSIBLE.
- AREAS OF SMOKE WILL CONTINUE THROUGH THE WEEK.
- VERY HOT, DRY, AND BREEZY TO END THE WEEK.
SHORT TERM /THROUGH FRIDAY NIGHT/
ISSUED 308 PM MDT WED JUL 22 2026
SHOWERS AND THUNDERSTORMS ARE ALREADY ONGOING ACROSS THE WEST-
CENTRAL ID MOUNTAINS AND SE OREGON. A FLASH FLOOD WATCH REMAINS
IN EFFECT FOR THE WAPITI BURN AREA THIS AFTERNOON AND EARLY
EVENING FOLLOWING THIS THREAT. SYNOPTICALLY, THE UPPER-LEVEL
RIDGE CENTERED ACROSS THE SOUTH-CENTRAL U.S., COMBINED WITH AN
UPPER-LEVEL TROUGH OFF THE COAST, WILL CONTINUE TO TRANSPORT
MONSOONAL MOISTURE ACROSS THE AREA UNDER SOUTHERLY FLOW ALOFT. A
SHORTWAVE IMPULSE IS LIFTING NORTH OUT OF NEVADA, WHICH WILL
CONTINUE PRODUCING NUMEROUS SHOWERS AND THUNDERSTORMS OVER THE
WEST-CENTRAL ID MOUNTAINS THROUGH EVENING. THUNDERSTORMS WILL BE
CAPABLE OF PRODUCING HEAVY RAIN, CREATING A RISK OF FLASH
FLOODING AND DEBRIS FLOWS, ESPECIALLY OVER BURN SCARS AND STEEP
TERRAIN. ADDITIONALLY, INSTABILITY WILL CONTINUE TO BUILD THIS
AFTERNOON FOR ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS MOST OF SOUTHEAST OREGON AND THE HIGHER TERRAIN SOUTH OF
THE SNAKE RIVER IN SOUTHWEST IDAHO. HEAVY RAIN WILL BE POSSIBLE
IN STRONGER STORMS WITH GUSTS TO 45 MPH. MOST LOWER ELEVATIONS
WILL SEE A LESS THAN 10% CHANCE OF SHOWERS AND THUNDERSTORMS
TODAY. AREAS OF SMOKE FROM REGIONAL WILDFIRES WILL PERSIST
TODAY, ESPECIALLY ACROSS EAST-CENTRAL OREGON AND WEST-CENTRAL
IDAHO INTO THE TREASURE VALLEY.
ON THURSDAY, THE FLOW ALOFT WILL TURN SOUTHWESTERLY ALOFT AS
THE RIDGE AXIS STARTS TO MOVE EAST, PUSHING DEEPER MONSOONAL
MOISTURE OUT OF THE AREA. HOWEVER, A WEAK IMPULSE AHEAD OF THE
TROUGH OFF THE COAST WILL BRING A 10-30% CHANCE OF SHOWERS AND
THUNDERSTORMS TO EASTERN OREGON AND WESTERN IDAHO IN THE
AFTERNOON AND EVENING. INSTABILITY WILL EXTEND INTO THE LOWER
ELEVATIONS, BRINGING A BETTER CHANCE FOR THUNDERSTORMS TO REACH
THE TREASURE VALLEY THAN PREVIOUS DAYS. STORMS WILL BE CAPABLE
OF GUSTY WINDS UP TO 50 MPH. OTHERWISE, SOUTHWEST FLOW WILL
BRING HOTTER TEMPERATURES WITH LOWER VALLEYS FORECAST TO REACH
AROUND 100 DEGREES. THIS HAS PROMPTED A HEAT ADVISORY FROM 2PM
MDT THURSDAY TO 9 PM MDT SATURDAY. ON FRIDAY, TEMPERATURES WILL
BE VERY HOT WITH LOWER VALLEYS APPROACHING 105 DEGREES. WINDS
WILL BECOME BREEZY IN SOUTHEAST OREGON STARTING THURSDAY THEN
BECOMING WIDESPREAD ACROSS THE AREA FRIDAY, WITH GUSTS 20-35 MPH
OVERSPREAD THE HIGHER ELEVATIONS. MUCH DRIER AIR WILL ARRIVE
FROM THE WEST, LIMITING THUNDERSTORM POTENTIAL TO SOUTH-CENTRAL
IDAHO AND INCREASING FIRE WEATHER CONCERNS. SOUTHWEST FLOW
ALOFT WILL TRANSPORT SOME OF THE SMOKE AWAY FROM THE AREA, BUT
DRAINAGE WINDS EACH NIGHT WILL CONTINUE TO BRING SMOKE IMPACTS
TO SOME AREAS.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
ISSUED 308 PM MDT WED JUL 22 2026
SUNDAY LOOKS SLIGHTLY COOLER THAN SATURDAY, ESPECIALLY IN OREGON
ZONES, AS PART OF THE UPPER TROUGH OFF THE NORTHWEST COAST MOVES
INLAND ACROSS WA. MOST OF OUR CWA WILL BE SUNNY AND DRY BUT MONSOON
MOISTURE WILL STILL CLIP SOUTH-CENTRAL IDAHO, WITH A SLIGHT BOOST
FROM HURRICANE FAUSTO AS IT HEADS WESTWARD ACROSS THE SUBTROPICAL
PACIFIC. FORECAST HAS A 15 PERCENT CHANCE OF THUNDERSTORMS IN TWIN
FALLS COUNTY SUNDAY. MONDAY THROUGH WEDNESDAY SHOULD BE DRY IN ALL
AREAS AND SEVERAL DEGREES COOLER THAN PREVIOUS DAYS, AS MORE OF THE
UPPER TROUGH OFF THE NORTHWEST COAST COMES INLAND.
AVIATION /06Z THURSDAY THROUGH FRIDAY/
ISSUED 1148 PM MDT WED JUL 22 2026
GENERALLY VFR, WITH AREAS OF MVFR DUE TO WILDFIRE SMOKE.
VISIBILITY WILL BE AT A MINIMUM OVERNIGHT, WITH IMPROVEMENT DURING
THE PEAK OF DAYTIME HEATING. SHOWERS AND THUNDERSTORMS WILL LINGER
INTO THE OVERNIGHT HOURS ACROSS EASTERN OREGON, THEN FLARE AGAIN
THURSDAY AFTERNOON. SURFACE WINDS: VARIABLE LESS THAN 10 KT
OVERNIGHT, EXCEPT VRB15G25KT NEAR STORMS, BECOMING WNW 10-15 KT
AFTER 20Z. WINDS ALOFT AT 10KFT MSL: WSW AROUND 10 KT.
KBOI...VFR WITH MID/HIGH CLOUDS, THEN VISIBILITY REDUCTIONS DUE TO
WILDFIRE SMOKE OVERNIGHT INTO EARLY THURSDAY. HIGH DENSITY ALTITUDE
THURSDAY AFTERNOON. SHOWERS AND THUNDERSTORMS POSSIBLE BETWEEN 22Z
THURSDAY AND 03Z FRIDAY. SURFACE WINDS: VARIABLE LESS THAN 10 KT
OVERNIGHT BECOMING WNW AROUND 10 KT AFTER 20Z.
BOI WATCHES/WARNINGS/ADVISORIES
ID...AIR QUALITY ALERT UNTIL 2 PM MDT FRIDAY FOR IDZ011-012-014-033.
FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
EVENING FOR IDZ401-402-423.
HEAT ADVISORY FROM 2 PM THURSDAY TO 9 PM MDT SATURDAY FOR
IDZ012-014-016-033.
OR...AIR QUALITY ALERT UNTIL 2 PM MDT /1 PM PDT/ FRIDAY FOR
ORZ061>064.
FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
EVENING FOR ORZ670>675.
HEAT ADVISORY FROM 2 PM MDT /1 PM PDT/ THURSDAY TO 9 PM MDT /8
PM PDT/ SATURDAY FOR ORZ063-064.
RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR ORZ670>672.
RED FLAG WARNING FROM NOON MDT /11 AM PDT/ TO 9 PM MDT /8 PM
PDT/ THURSDAY FOR ORZ673>675.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....MC
SHORT TERM...CH
LONG TERM....LC
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