164
FXUS65 KBOI 192350
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
550 PM MDT MON OCT 19 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- HIGH TEMPERATURES 5 TO 15 DEGREES ABOVE NORMAL THROUGH
WEDNESDAY.
- SHOWER AND THUNDERSTORM CHANCES RETURN STARTING TUESDAY
AFTERNOON, AND INCREASING WEDNESDAY THROUGH FRIDAY.
- COOLER TEMPERATURES BY THE END OF THE WEEK AND INTO THE
WEEKEND.
SHORT TERM /THROUGH WEDNESDAY NIGHT/
ISSUED 259 PM MDT MON OCT 19 2026
AN UPPER LOW OFF THE OREGON COAST WILL CONTINUE TO TRACK SOUTH
OVER THE NEXT DAY. OUR AREA WILL SEE SOUTHERLY WINDS ALOFT
CONTINUE FOR TUE/WED. THIS KEEPS TEMPERATURES 10-15 DEGREES
ABOVE NORMAL, OR LOW-MID 70S IN THE VALLEYS AND UPPER 60S IN THE
MTNS. THE SOUTHERLY FLOW WILL ALSO DRAW UP MOISTURE, WHICH WILL
BE REFLECTED BY 20 DEGREE DEW POINT TEMPERATURE RISES AND
PRECIPITABLE WATER VALUES PUSHING PAST THE 90TH PERCENTILE.
THIS MOISTURE WILL BE FUEL FOR SHOWER AND POSSIBLE THUNDERSTORM
DEVELOPMENT STARTING LATE TUESDAY AFTERNOON, AND CONTINUING
BEYOND WEDNESDAY NIGHT. DAYTIME HEATING ALONG WITH ELEVATED
INSTABILITY WILL SUPPORT AFTERNOON/EVENING DEVELOPMENT OVER THE
W-CENTRAL ID MTNS AND ALONG THE NORTHERN NV BORDER LATE TUESDAY.
AN EMBEDDED WAVE LIFTING THROUGH THE AREA TUESDAY NIGHT WILL
EXTEND A LOW CHANCE OF SHOWERS (AND POSSIBLY A RUMBLE OF
THUNDER) ACROSS MUCH OF THE AREA. A LOW CHANCE OF SHOWERS AND
THUNDERSTORMS RETURNS TO THE W-CENTRAL IDAHO MTNS AND AREAS
ALONG THE NV BORDER WEDNESDAY AFTERNOON/EVENING. WEDNESDAY NIGHT
WILL SEE PRECIPITATION CHANCES INCREASE FROM SOUTH TO NORTH AS
THE CLOSED LOW PUSHES ONTO THE S-CENTRAL CA COAST AND A
SECONDARY WAVE APPROACHES THE PAC NW.
LONG TERM /THURSDAY THROUGH MONDAY/
ISSUED 259 PM MDT MON OCT 19 2026
WIDESPREAD SHOWERS WILL BE THE STORY THURSDAY INTO FRIDAY, AS
THE LOW LIFTS NORTHEAST OVER OUR AREA FROM CALIFORNIA. WHILE
CLOUD COVER WILL HELP LIMIT DAYTIME INSTABILITY, COOLING ALOFT
WILL ALLOW FOR WEAK INSTABILITY TO DEVELOP, RESULTING IN A
SLIGHT CHANCE OF EMBEDDED THUNDERSTORMS. ANY THUNDERSTORMS WILL
RESULT IN LOCALIZED HEAVIER RAINFALL RATES/TOTALS UNDERNEATH THE
CORE. AT LEAST FOR THURSDAY, SOUTHERLY FLOW ALOFT WILL KEEP
SNOW LEVELS ON THE HIGHER SIDE (9-10KFT MSL), GIVING RAIN ITS
OPPORTUNITY TO SHINE AS THE DOMINATE PRECIPITATION TYPE. OVER
THE COURSE OF THURSDAY THROUGH FRIDAY, GUIDANCE CONTINUES TO
TREND UPWARDS ON TOTAL ACCUMULATIONS, WITH LOWER ELEVATIONS
RANGING FROM 0.15-0.50 INCHES (LOWEST IN EASTERN OREGON),
MOUNTAIN VALLEYS RANGING FROM 0.50-0.80 INCHES, AND HIGHEST
ELEVATIONS UP TO 1.25 INCHES; WITH THE BULK OF THE PRECIPITATION
FALLING LATE THURSDAY INTO EARLY FRIDAY. WHILE THIS WILL BE
MORE STRATIFORM AND LONG DURATION IN NATURE, STEEP TERRAIN/BURN
SCARS MAY EXPERIENCE INCREASED RUNOFF AND LAND MOVEMENT.
A COLD FRONT ON FRIDAY WILL BRING A RATHER SHARP END TO THE
PRECIP AND A COOLDOWN AS IT MOVES ACROSS OUR AREA FROM WEST TO
EAST. TEMPERATURES COMES FRIDAY WILL DROP AROUND 5 DEGREES
BELOW NORMAL. ANOTHER, PROBABLY MORE NOTABLE, CONSEQUENCE OF THE
COLD FRONT WILL BE THE GUSTY WEST-NORTHWEST WINDS THAT WILL
ACCOMPANY IT. FRIDAY AFTERNOON, WINDS ACROSS RIDGE TOPS AND OPEN
TERRAIN WILL GUST TO 20- 35 MPH. THE STRONGEST WINDS, HOWEVER,
WILL BLOW IN THE SNAKE RIVER PLAIN EAST OF MOUNTAIN HOME WHERE
GUSTS WILL REACH 35-45 MPH. LOWERING SNOW LEVELS ON FRIDAY
BEHIND THE FRONT WILL ALLOW FOR A TRANSITION TO SNOW/WINTRY MIX
FOR ELEVATIONS ABOVE 6.5 KFT MSL. ALTHOUGH THIS SWITCH WILL BE
AT THE TAIL END OF THE PRECIPITATION, SO ONLY A DUSTING OF SNOW
IS EXPECTED ALONG HIGH ELEVATION PASSES SUCH AS BANNER SUMMIT.
PATTERN UNCERTAINTY INCREASES BEHIND THIS SYSTEM, HOWEVER
SATURDAY AT THE VERY LEAST SHOULD BE DRY WITH TEMPERATURES
WARMING TO NEAR NORMAL AGAIN. WHILE ENSEMBLE CONSENSUS IS
ANOTHER TROUGH DIGGING DOWN TO THE WEST COAST COME SUNDAY, THERE
IS CONSIDERABLE UNCERTAINTY IN HOW THIS LOW INTERACTS WITH THE
DEPARTING ON AND WHEN/IF IT GET BROUGHT INLAND OVER OUR AREA.
AVIATION /00Z TUESDAY THROUGH WEDNESDAY/
ISSUED 541 PM MDT MON OCT 19 2026
VFR AND HIGH CLOUDS. LOCALLY REDUCED VISIBILITY DUE TO SMOKE
FROM PRESCRIBED FIRES. SURFACE WINDS: VARIABLE 5-10 KT, EXCEPT
E 10-20 KT OVER BOISE MOUNTAINS TO KJER, AND S 10-20 KT FOR
SOUTH OF THE W SNAKE PLAIN IN S-CENTRAL IDAHO. WINDS ALOFT AT
10KFT MSL: S TO SE 10-20 KT.
KBOI...VFR AND HIGH CLOUDS. SURFACE WINDS: NW AROUND 3-7 KT,
THEN SE 4-8 KT AFTER SUNSET.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
AVIATION.....SH
SHORT TERM...DG
LONG TERM....DG
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