063
FXUS65 KBOI 151749
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1149 AM MDT SAT AUG 15 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- FIRE WEATHER RISK CONTINUES DUE TO THUNDERSTORM ACTIVITY TODAY.
- THUNDERSTORMS WITH HEAVY RAIN MAY ALSO INCREASE THE RISK FOR
FLASH FLOODING, ESPECIALLY FOR VULNERABLE BURN SCARS TODAY.
- TEMPERATURES NEAR NORMAL THROUGH EARLY NEXT WEEK, THEN A FEW
DEGREES OF WARMING EXPECTED BY LATE WEEK.
SHORT TERM /THROUGH MONDAY NIGHT/
ISSUED 235 AM MDT SAT AUG 15 2026
ISOLATED, WEAK SHOWERS AND THUNDERSTORMS ARE LINGERING NEAR THE
NEVADA BORDER EARLY THIS MORNING, BUT ARE EXPECTED TO TAPER OFF
IN THIS AREA BY MID/LATE MORNING. A SHORTWAVE TROUGH IS ON
TRACK TO SWING THROUGH THE PACNW THIS AFTERNOON, GENERATING THE
NEXT ROUND OF SCATTERED SHOWERS/THUNDERSTORMS ACROSS THE
FORECAST AREA THIS AFTERNOON AND EVENING DUE TO PERSISTING
MONSOON MOISTURE. ACTIVITY WILL MAINLY FAVOR FAR EAST OREGON
AND THE HIGHER TERRAIN OF SOUTHWEST IDAHO, BUT A 15-25% CHANCE
OF STORMS ARE ALSO FORECAST ACROSS THE SW IDAHO VALLEYS. WHILE
PRECIPITABLE WATER VALUES ARE ANTICIPATED TO BE LOWER THAN
FRIDAY AFTERNOON, VALUES WILL REMAIN SUPPORTIVE OF HEAVY
DOWNPOURS UNDER STORM CORES...LEADING TO A RISK OF FLASH
FLOODING ON STEEP/ROCKY TERRAIN AND VULNERABLE BURN SCARS.
MODELS ARE ALSO INDICATIVE OF GUSTY OUTFLOW WINDS WITH STRONGER
STORMS, WITH LOCALIZED GUSTS TO 45 MPH POSSIBLE.
ACTIVITY WILL TAPER OFF FOR THE OVERNIGHT PERIOD (TONIGHT) INTO
SUNDAY, BUT LINGERING MOISTURE AND SUNDAY AFTERNOON INSTABILITY
WILL KEEP A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS OVER THE
HIGHER TERRAIN OF CENTRAL AND SOUTH-CENTRAL IDAHO. OTHERWISE,
BUILDING HIGH PRESSURE WITH SOUTHWEST FLOW ALOFT IS FORECAST
SUNDAY, BRINGING A DRYING AND WARMING TREND ACROSS MUCH OF THE
AREA. A NEW SWATH OF MONSOON MOISTURE WILL PASS THROUGH THE AREA
AGAIN ON MONDAY, CONTINUING A CHANCE OF SHOWERS AND THUNDERSTORMS
OVER THE HIGHER TERRAIN OF NORTHEAST OREGON, AND CENTRAL/SOUTH-
CENTRAL IDAHO MONDAY AFTERNOON. WHILE TEMPERATURES WILL BE NEAR
NORMAL TODAY, EXPECT TEMPS TO RISE A COUPLE OF DEGREES ABOVE
NORMAL FOR SUNDAY AND MONDAY UNDER THE INFLUENCE OF THE UPPER
RIDGE AND SOUTHWESTERLY FLOW ALOFT.
LONG TERM /TUESDAY THROUGH SATURDAY/
ISSUED 235 AM MDT SAT AUG 15 2026
A WEAK SHORTWAVE TROUGH WILL SKIRT THROUGH THE NORTHWESTERN
U.S. TUESDAY AND WEDNESDAY, FLATTENING THE AFOREMENTIONED UPPER
RIDGE AND NUDGING THE MONSOONAL MOISTURE TOWARD THE EAST. AS A
RESULT, DRY CONDITIONS WITH SLIGHT COOLING IS FORECAST FOR MID-
WEEK. THE SOUTHWEST U.S. RIDGE WILL MAKE A RAPID RETURN BY
THURSDAY AND FRIDAY, AMPLIFYING NORTHWARD INTO CANADA WHILE A
PACIFIC TROUGH APPROACHES THE WEST COAST. THIS PATTERN WILL
SUPPORT RAPID HEATING AND THE INFLUX OF MONSOONAL MOISTURE ONCE
AGAIN, WITH SHOWER AND THUNDERSTORM CHANCES INCREASING BY
FRIDAY.
AVIATION /18Z SATURDAY THROUGH SUNDAY/
ISSUED 1148 AM MDT SAT AUG 15 2026
GENERALLY VFR. INCREASING COVERAGE OF SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS FAR E OREGON AND SW IDAHO BY LATE MORNING
AND AFTERNOON. STORMS CAPABLE OF SMALL HAIL, ERRATIC OUTFLOWS UP
TO 45 KT, AND MVFR/IFR DOWNPOURS. SURFACE WINDS OUTSIDE OF
STORMS: GENERALLY SE-SW 5-15 KT, WITH AREAS OF GUSTS TO 20-25
KT. WINDS ALOFT AT 10KFT MSL: SW-S 5-20 KT.
KBOI...VFR. ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS
DEVELOPING IN SW IDAHO THIS AFTERNOON, WITH A 25 TO 40% CHANCE
OF HITTING KBOI TERMINAL. STORMS CAPABLE OF 30-45 KT OUTFLOW
GUSTS AND BRIEF DOWNPOURS. SURFACE WINDS: SE 5-15 KT, WITH GUSTS
TO 15-25 KT THIS MORNING AND EARLY AFTERNOON. TRANSITIONING TO
ERRATIC/VARIABLE DURING LATE AFTERNOON AND EVENING DUE TO NEARBY
STORM ACTIVITY.
SUNDAY OUTLOOK...SHOWERS AND THUNDERSTORMS LARGELY TAPER OFF
SUNDAY, WITH ISOLATED COVERAGE ACROSS CENTRAL AND SOUTH-CENTRAL
ID. SURFACE WINDS: SW-NW 5-10 KT SUNDAY. PERIODS OF SMOKE NEAR
KBKE/KBNO.
BOI WATCHES/WARNINGS/ADVISORIES
ID...RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR IDZ400-420-
423-424-426.
FLASH FLOOD WATCH UNTIL 9 PM MDT THIS EVENING FOR IDZ013.
OR...RED FLAG WARNING UNTIL 9 PM MDT /8 PM PDT/ THIS EVENING FOR
ORZ672-673.
RED FLAG WARNING UNTIL 8 PM PDT THIS EVENING FOR ORZ674-675.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....CH
SHORT TERM...SH
LONG TERM....SH
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