347
FXUS65 KBOI 050337
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
837 PM MST WED FEB 4 2026
DISCUSSION
HIGH CLOUDS ARE MOVING IN ACROSS THE REGION THIS
EVENING, WITH GENERALLY CALM CONDITIONS AND ABOVE NORMAL
TEMPERATURES CONTINUING OVERNIGHT. PATCHY VALLEY FOG WILL OCCUR
NEAR ONTARIO, OR TONIGHT, WITH LIGHT SOUTHEAST WINDS REDUCING
THE RISK OF FOG NEAR CALDWELL AND BOISE. NEAR RECORD HIGHS WILL
CONTINUE ACROSS AREA VALLEYS TOMORROW WITH HIGHS IN BOISE
REACHING THE MID TO UPPER 50S. THE RIDGE OF HIGH PRESSURE WILL
REMAIN CENTERED OVER SOUTHERN IDAHO AND NORTHERN NEVADA THROUGH
FRIDAY, WITH AIR STAGNATION CONCERNS AND ABOVE NORMAL
TEMPERATURES EXPECTED THROUGH THE WEEKEND. THE NEXT THREAT OF
PRECIPITATION STILL LOOKS TO COME LATE SUNDAY INTO MONDAY, WITH
VALLEY RAIN AND MOUNTAIN SNOW ACROSS THE REGION. NO UPDATES
NECESSARY TO THE FORECAST.
AVIATION
GENERALLY VFR. PATCHY MVFR-IFR VISIBILITY FROM HAZE/MIST
IN LOWER BASINS AND SHELTERED VALLEYS EARLY THU AM. SURFACE WINDS:
VARIABLE LESS THAN 10 KT, EXCEPT E-NE 10-15 KT IN S-CENTRAL IDAHO.
THEN, NE-SE 5-15 KT FOR MOST AREAS AFTER THU/16Z. WINDS ALOFT AT
10KFT MSL: VARIABLE 5-15 KT.
KBOI...VFR. SURFACE WINDS: SE 3-9 KT, BECOMING LIGHT AND VARIABLE
THU AFTERNOON.
AIR STAGNATION
WE'LL CONTINUE TO SEE LITTLE MOVEMENT IN THE
AIR MASS NEAR THE SURFACE AS THE REGION REMAINS UNDER A STRONG
HIGH PRESSURE. THE LOW MIXING HEIGHTS AND LIGHT WINDS WILL ALLOW
FOR THE CONTINUED COLLECTION OF POLLUTANTS NEAR THE SURFACE.
COMPLETE BREAKDOWN OF THE RIDGE AND TURNOVER OF THE AIR MASS IS
STILL ON TRACK WITH THE PASSAGE OF A COLD FRONT LATE SUN/MON.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT...HIGH PRESSURE ALOFT
WILL SLIDE TO OUR EAST LATE THUR/FRI. THIS WILL HAVE LITTLE
IMPACT ON THE WEATHER, THOUGH IT WILL LESSEN HIGH CLOUD COVER ON
THURSDAY AS MOISTURE ALOFT IS ROUTED TO THE NORTH AND EAST. AN
UPPER LOW WILL UNDERCUT THE RIDGE ON FRIDAY, TRACKING INTO
CENTRAL CA. WHILE PRECIPITATION STAYS WELL TO THE SOUTH (CENTRAL
NV), WE WILL SEE AN INCREASE IN CLOUDS THROUGH THE DAY WHICH
WILL ACT TO TAKE A FEW DEGREES OFF OF HIGH TEMPERATURES. WITH
THE HIGH OVERHEAD, WE REMAIN IN A DRY AND STAGNANT AIR MASS THAT
WILL SUPPORT VALLEY FOG DEVELOPMENT EACH MORNING. MTN VALLEYS
AND THE LOWER SNAKE PLAIN ARE THE MOSTLY LIKELY LOCATIONS TO
SEE FOG, WITH OVERNIGHT DRAINAGE WINDS LIMITING DEVELOPMENT
EAST OF THE CANYON/ADA COUNTY LINE IN THE SNAKE PLAIN. HIGH
TEMPERATURES WILL RUN 10-15 DEGREES ABOVE NORMAL WITH A FEW
SITES IN SE OREGON (BURNS, BAKER CITY AND HALFWAY) APPROACHING
RECORD HIGHS ON THURSDAY.
LONG TERM...SATURDAY THROUGH WEDNESDAY...A PATTERN CHANGE IS
STILL ON TAP FOR EARLY NEXT WEEK, AS THE UPPER-LEVEL RIDGE
SHIFTS EAST AND A TROUGH MOVES IN ACROSS OUR AREA. DETERMINISTIC
GUIDANCE IS CONTINUING TO RESOLVE THE COLD FRONT ASSOCIATED
WITH THE UPPER-LEVEL TROUGH SWINGING ACROSS OUR AREA LATE
SUNDAY/EARLY MONDAY. PRECIPITATION CHANCES ASSOCIATED WITH THIS
FRONT WILL INCREASE FROM WEST TO EAST SUNDAY AFTERNOON, WITH
PROBABILITIES MAXING OUT MONDAY MORNING AT 60-90% IN THE WEST
CENTRAL MOUNTAINS AND BOISE FOOTHILLS; ELSEWHERE CHANCES WILL
RANGE FROM 30-60%. WHILE SNOW LEVELS WILL INITIALLY START ON THE
HIGHER SIDE, 6-7KFT MSL, THE COLDER AIRMASS MOVING IN WILL
ALLOW FOR A TRANSITION TO SNOW/WINTRY MIX ACROSS MID- HIGH
ELEVATIONS. OROGRAPHIC LIFT WILL ACT TO KEEP SNOW SHOWERS GOING
LONGER ACROSS TERRAIN, OVER A TWO DAY PERIOD (SUNDAY AFTERNOON
THROUGH TUESDAY AFTERNOON) NBM PROBABILITIES OF AT LEAST 2
INCHES OF SNOW RANGE FROM 55-95% ABOVE 6000 FT MSL... THE HIGHER
END OF THAT WILL SEEN ACROSS THE HIGHEST ELEVATIONS.
WHILE SNOW LEVELS WILL DROP TO VALLEY FLOORS OVERNIGHT TUESDAY,
THE QUESTIONS BECOMES WHETHER NOT THERE WILL BE SUFFICIENT
MOISTURE AND FORCING TO SUPPORT SHOWERS. WHILE DETERMINISTIC
SOLUTIONS DIVERGE ON THE PATTERN EVOLUTION BEYOND MONDAY,
ENSEMBLE OUTPUT FAVORS UNSETTLED CONDITIONS FOR OUR AREA THROUGH
WEDNESDAY. TEMPERATURES MONDAY AND BEYOND WILL DROP TO MORE
SEASONABLE VALUES FOR THIS TIME OF YEAR, ALTHOUGH STILL LEANING
A FEW DEGREES ABOVE NORMAL.
BOI WATCHES/WARNINGS/ADVISORIES
ID...AIR STAGNATION ADVISORY UNTIL 5 AM MST MONDAY
IDZ012-014-016-033.
OR...AIR STAGNATION ADVISORY UNTIL 5 AM MST /4 AM PST/ MONDAY
ORZ062>064.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...SA
AVIATION.....SH
AIR STAGNATION...DG
SHORT TERM...DG
LONG TERM....NF
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