273
FXUS65 KBOI 160337
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
837 PM MST THU JAN 15 2026
DISCUSSION
DENSE FOG HAS BECOME WIDESPREAD ALL ACROSS THE
SNAKE BASIN IN OUR CWA. THE FOG HAS CREATED NOT ONLY A HAZARD
FOR TRAVEL, BUT ALSO A HAZARD FOR PEDESTRIANS, AS IT HAS
DEPOSITED A THIN COATING OF CLEAR ("BLACK") ICE ON ROADS AND
SIDEWALKS. A DENSE FOG ADVISORY RUNS UNTIL 11 AM MST FRIDAY,
AND WE WILL ALMOST CERTAINLY NEED ANOTHER ADVISORY FRIDAY NIGHT
INTO SATURDAY, AND AGAIN SATURDAY NIGHT INTO SUNDAY. WE ARE
ISSUING THEM ONE AT A TIME BECAUSE FOG SHOULD EASE SOME EACH
AFTERNOON. HIGH PRESSURE AND WARM AIR ALOFT ABOVE THE COLDER
VALLEYS HAS CREATED A STRONG INVERSION THAT WILL CONTINUE INTO
NEXT WEEK, PROBABLY BREAKING MID-WEEK. UNTIL THEN, MORE OF THE
SAME. NO UPDATE.
AVIATION
WIDESPREAD IFR-LIFR FOG THROUGHOUT THE SNAKE PLAIN,
WITH DENSE FOG EXISTING OVERNIGHT THROUGH FRIDAY AFTERNOON.
CONFIDENCE IN TIMING OF CLEARING AND COVERAGE WILL REMAIN LOW.
OTHERWISE VFR CONDITIONS UNDER CLEAR SKIES. SURFACE WINDS:
VARIABLE UP TO 10 KT. WINDS ALOFT AT 10KFT MSL: N 15-30 KT.
KBOI...IFR-VLIFR CONDITIONS TO PERSIST OVERNIGHT THROUGH FRIDAY
MORNING. EARLIEST IMPROVEMENT TO MVFR-VFR CONDITIONS LOOKS TO BE
FRIDAY AFTERNOON, HOWEVER CHANCES ARE STILL 30% FOR IFR CONDITIONS
DURING THAT PERIOD AND AFTER. SURFACE WINDS: LIGHT AND VARIABLE
UNDER 6 KT.
WEEKEND OUTLOOK...VALLEY FOG AND LOW STRATUS TO CONTINUES
OVER THE WEEKEND, WITH VFR CONDITIONS AND CLEAR SKIES ABOVE
THE INVERSION. LIGHT SURFACE WINDS THROUGHOUT.
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.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT...UPPER LEVEL RIDGE
CONTINUES TO IMPACT THE AREA WITH FOG AND STRATUS ACROSS THE
SNAKE BASIN, AND MILD TEMPERATURES ABOVE THE FOG. MOSTLY SUNNY
SKIES OUTSIDE OF THE SNAKE BASIN. THIS FOG/STRATUS IS LIKELY TO
CONTINUE TONIGHT WITH LITTLE IMPROVEMENT OVER THE NEXT SEVERAL
DAYS. WE LOWERED THE TEMPERATURES IN THE SNAKE BASIN FOR THE FOG
AND STRATUS OVER THE NEXT SEVERAL DAYS. ABOVE THE INVERSION,
TEMPERATURES REMAIN AROUND 10 DEGREES ABOVE NORMAL. AREAS OF FOG
DEVELOP IN THE MOUNTAIN VALLEYS, INCLUDING THE LONG VALLEY AND
BAKER VALLEY OVERNIGHT EVERY NIGHT OVER THE NEXT FEW DAYS.
LONG TERM...SUNDAY THROUGH THURSDAY...UPPER-LEVEL RIDGING
CONTINUES INTO EARLY NEXT WEEK, WITH THE RIDGE AXIS SHIFTING
WEST ENOUGH TO CAUSE MORE NORTHERLY FLOW ALOFT. MODEL CLUSTERS
AND ENSEMBLES KEEP RIDGING IN PLACE AT LEAST THROUGH TUESDAY
AFTERNOON, AFTER WHICH THE RIDGE WILL WEAKEN BUT STILL PERSIST.
THE PATTERN CHANGE COMES IN WEDNESDAY INTO THURSDAY, WHEN AN
UPPER-LEVEL SHORTWAVE TROUGH MOVES OVER THE REGION.
PRECIPITATION AMOUNTS AND TROUGH INTENSITY VARY SUBSTANTIALLY
ACROSS MODELS, HOWEVER, THE SOLUTIONS AGREE ON PROVIDING *SOME*
RELIEF AGAINST THIS INVERSION. SNOW CHANCES ALSO RETURN TO THE
HIGHER ELEVATIONS WITH THIS SYSTEM AROUND 30% ON THURSDAY.
BOI WATCHES/WARNINGS/ADVISORIES
ID...AIR STAGNATION ADVISORY UNTIL 5 AM MST MONDAY
IDZ011>014-016-028-033.
DENSE FOG ADVISORY UNTIL 1 PM MST FRIDAY IDZ012-014-016-033.
OR...AIR STAGNATION ADVISORY UNTIL 5 AM MST /4 AM PST/ MONDAY
ORZ061>064.
DENSE FOG ADVISORY UNTIL 1 PM MST /NOON PST/ FRIDAY ORZ064.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...LC
AVIATION.....JY
AIR STAGNATION...DG
SHORT TERM...KA
LONG TERM....CH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page