631
FXUS65 KBOI 200609
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1209 AM MDT MON JUL 20 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- ISOLATED SHOWERS AND THUNDERSTORMS ALONG THE IDAHO/NEVADA
BORDER TODAY.
- AREAS OF SMOKE IN SOUTHEAST OREGON, DRIFTING INTO SOUTHWEST
IDAHO THROUGH THE WEEK.
- HOT TEMPERATURES THIS WEEK, HOTTEST ON MONDAY WITH HEAT
ADVISORIES IN THE SNAKE PLAIN AND HIGH DESERT.
- SHOWERS/THUNDERSTORMS INCREASE THROUGH MIDWEEK WITH HEAVY
RAINFALL POSSIBLE ESPECIALLY ON WEDNESDAY.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
ISSUED 159 PM MDT SUN JUL 19 2026
HOT AND DRY CONDITIONS AS AN UPPER LEVEL RIDGE REMAINS IN PLACE.
SOUTHWESTERLY FLOW TODAY IS TRANSPORTING A BAND OF ALTOCUMULUS
WITH VIRGA SHOWERS IN IT, BUT THE OVERALL CHANCE OF STORMS IS
LOW. ONLY A SMALL PORTION OF SOUTH-CENTRAL IDAHO IN OUR AREA,
SOUTH OF THE MAGIC VALLEY, WILL HAVE ISOLATED THUNDERSTORMS.
THESE COULD PRODUCE GUSTY WINDS, LIGHTNING, AND HEAVY RAIN, BUT
WILL STAY RELEGATED TO THAT SMALL CORNER OF OUR AREA. HIGH
TEMPERATURES REMAIN HOT WITH TEMPERATURES IN THE SNAKE PLAIN
AROUND 100 DEGREES. SOME SEASONALLY BREEZY WINDS ACROSS THE
AREA WITH GUSTS 15-25 MPH.
ON MONDAY, SOUTHERLY FLOW ALOFT BRINGS THE RETURN MONSOONAL
MOISTURE THAT EVENING, BUT NOT BEFORE THE HOTTEST DAY IN OUR
FORECAST. HEAT ADVISORIES HAVE BEEN ISSUED WITH TEMPERATURES IN
THE SNAKE PLAIN EXPECTED TO BE AS HIGH AS 105 DEGREES WITH
MORNING TEMPERATURES IN THE LOW 70S. SHOWER AND THUNDERSTORM
CHANCES WILL RISE TO 20-40% NEAR THE IDAHO/NEVADA BORDER IN THE
AFTERNOON/EVENING. NORTHWEST WINDS WILL BECOME BREEZY LATE IN
THE DAY WITH WIND GUSTS 15-30 MPH. ON TUESDAY, INCREASING
MOISTURE WILL COOL TEMPERATURES A COUPLE DEGREES, BUT IT WILL
STILL BE HOT. SHOWER AND THUNDERSTORM CHANCES WILL INCREASE
ACROSS THE HIGHER TERRAIN BUT REMAIN LIMITED OVER THE LOWER
ELEVATIONS. STORMS WILL BE CAPABLE OF GUSTY WINDS AND BRIEF
HEAVY RAIN. SMOKE WILL PERSIST ACROSS THE AREA MONDAY AND
TUESDAY.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED 159 PM MDT SUN JUL 19 2026
SOUTHERLY FLOW ALOFT WILL REMAIN OVER THE AREA WEDNESDAY, WITH THE
REGION BETWEEN THE UPPER-LEVEL RIDGE IN THE SOUTH-CENTRAL U.S. AND
UPPER-LEVEL TROUGHING OFF THE PACIFIC NW COAST. THE GREATEST CHANCES
FOR SHOWERS AND THUNDERSTORMS IN THE EXTENDED PERIOD WILL BE ON
WEDNESDAY, AS AN EMBEDDED SHORTWAVE TROUGH LIFTS NORTH THROUGH THE
GREAT BASIN. THIS FEATURE SHOULD PROVIDE ADDITIONAL LIFT FOR
CONVECTION, WITH MOST AREAS SEEING A 20-60% CHANCE OF
SHOWERS/THUNDERSTORMS. PRECIPITABLE WATER VALUES WILL STILL BE
HOVERING AROUND THE 95TH PERCENTILE DURING THIS TIME, CREATING THE
RISK OF HEAVY RAIN AND FLASH FLOODING, ESPECIALLY OVER BURN SCARS
AND STEEP TERRAIN. STARTING THURSDAY, THE FLOW ALOFT WILL TURN
SOUTHWESTERLY AS AN UPPER TROUGH DEEPENS OFF THE PACIFIC NORTHWEST
COAST. THIS WILL GRADUALLY PUSH DEEPER MOISTURE TO THE EAST WITH A
DRYING TREND FROM THE WEST THROUGH THE END OF THE WEEK. BY THE
WEEKEND, ONLY MINIMAL CHANCES FOR PRECIPITATION WILL PERSIST ACROSS
OUR EASTERN ZONES. SOUTHWEST FLOW WILL BRING HOT, DRY, AND BREEZY
CONDITIONS LATE WEEK INTO THE WEEKEND. SMOKE WILL LIKELY CONTINUE TO
IMPACT MUCH OF THE AREA THROUGH THE END OF THE WEEK, 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 MONDAY FOR ORZ061-062.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....NF
SHORT TERM...JM
LONG TERM....CH
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