116
FXUS65 KBOI 151032
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
332 AM MST THU JAN 15 2026
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
THE LARGE SCALE
PATTERN REMAINS LOCKED IN PLACE THROUGH THE SHORT TERM. WE'LL
SEE SOME SUBTLE CHANGES IN THE UPPER LEVELS AS THE RIDGE
AMPLIFIES AND REPOSITIONS ALONG THE WEST COAST BY FRIDAY. THIS
WILL BRING SOME COOLING ALOFT (ABOVE 10KFT MSL) AS THE REGION
FALLS UNDER NORTHERLY FLOW. DON'T EXPECT MUCH IMPACT NEAR THE
SURFACE AS THE INVERSION REMAINS ENTRENCHED ACROSS THE VALLEYS.
WILL NEED TO WATCH FOR ANY COLDER/DRIER AIR THAT COULD SNEAK
INTO THE AREA FROM EASTERN ID ON FRIDAY AS WE SEE AN UPTICK IN
EASTERLY WINDS. THIS COULD IMPACT MTN TEMPS AND VALLEY FOG
COVERAGE IN THE SNAKE PLAIN MOSTLY EAST OF THE CAN/ADA COUNTY
LINE. MAIN CHALLENGES WILL REMAIN EVOLUTION OF FOG COVERAGE IN
VALLEYS AND ACCOMPANYING TEMPERATURE VARIATION BETWEEN THE
FOG/SUN LINE. HAVE CONTINUED TO LEAN ON MIX OF HIGH RESOLUTION
MODELS AND PERSISTENCE FOR THE FORECAST.
LONG TERM...SUNDAY THROUGH THURSDAY
THOUGH IN VARYING FORM,
THE UPPER RIDGE REMAINS IN PLACE THROUGH MID-WEEK. THIS WILL
KEEP THE REGION LOCKED UNDER A TEMPERATURE INVERSION LIKELY
THROUGH WEDNESDAY. TONIGHT'S DETERMINISTIC AND ENSEMBLE GUIDANCE
CONTINUES TO SHOW THE RIDGE GIVING WAY TO A TROUGH LATE NEXT
WEEK, WHETHER A SYSTEM MOVING IN FROM THE PACIFIC (GFS) OR
WESTWARD EXPANSION OF THE HUDSON BAY LOW. WHILE THERE ARE
VARYING PRECIPITATION FORECASTS WITH THESE SOLUTIONS, BOTH WOULD
BE COLD ENOUGH TO MIX OUT THE INVERSION AND INTRODUCE AT LEAST
A 20-30% CHANCE OF LIGHT MTN SNOW BY NEXT THURSDAY (THINK
SNOW). UNTIL THEN, IT'S DRY WITH BELOW NORMAL TEMPERATURES IN
THE LOWER VALLEYS AND ABOVE NORMAL TEMPERATURES IN THE
MOUNTAINS.
AVIATION
WIDESPREAD IFR IN THE SNAKE PLAIN AND MTN VALLEYS
THROUGH 18Z THIS MORNING. LOCAL IFR WILL PERSIST ALL DAY FROM WEST
OF KEUL TO KONO. CONFIDENCE IN TIMING OF CLEARING AND COVERAGE
WILL REMAIN LOW. OTHERWISE VFR CONDITIONS UNDER MOSTLY CLEAR
SKIES. SURFACE WINDS: VARIABLE UP TO 10 KT. WINDS ALOFT AT 10KFT
MSL: NW 15-25 KT.
KBOI...VLIFR CONDITIONS WILL PERSIST THROUGH ABOUT 18Z. EXPECT
IMPROVEMENT TO IFR BETWEEN 17-19Z, AND MVFR-VFR BETWEEN 19-20Z.
FOG AND IFR-VLIFR CONDITIONS WILL LIKELY RETURN IN THE EVENING
(02-05Z). LIGHT SURFACE WINDS THROUGH THE DAY.
WEEKEND OUTLOOK...A CONTINUATION OF IFR CONDITIONS IN VALLEY FOG
WITH BRIEF BREAKS DURING THE AFTERNOON. EXCEPTION WOULD BE
ACROSS THE LOWEST ELEVATIONS (VICINITY KONO) WHERE IFR MAY
PERSIST THROUGH THE WEEKEND. MTN VALLEYS WILL LIKELY SEE A VFR
WINDOW BETWEEN 18-00Z EACH AFTERNOON. OTHERWISE VFR UNDER MOSTLY
CLEAR SKIES WITH LIGHT SURFACE WINDS AND NORTHERLY WINDS ALOFT.
AIR STAGNATION
A STABLE AIR MASS WILL KEEP STAGNANT
CONDITIONS IN PLACE INTO THE MIDDLE OF NEXT WEEK. THE
TEMPERATURE INVERSION AND LIGHT WINDS WILL ALLOW FOR LITTLE
MIXING ACROSS VALLEYS.
BOI WATCHES/WARNINGS/ADVISORIES
ID...AIR STAGNATION ADVISORY UNTIL 5 AM MST MONDAY
IDZ011>014-016-028-033.
DENSE FOG ADVISORY UNTIL 11 AM MST THIS MORNING IDZ012.
DENSE FOG ADVISORY UNTIL 11 AM MST THIS MORNING IDZ014.
OR...AIR STAGNATION ADVISORY UNTIL 5 AM MST /4 AM PST/ MONDAY
ORZ061>064.
DENSE FOG ADVISORY UNTIL 11 AM MST /10 AM PST/ THIS MORNING
ORZ064.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
SHORT TERM...DG
LONG TERM....DG
AVIATION.....DG
AIR STAGNATION...DG
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