797
FXUS65 KBOI 040351
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
851 PM MST TUE FEB 3 2026
DISCUSSION
HIGH CLOUDS ARE STREAMING INTO THE REGION THIS
EVENING, BRINGING LIGHT CLOUD COVER. HIGH PRESSURE WILL REMAIN
IN PLACE WITH GENERALLY LIGHT WINDS ACROSS THE AREA. PATCHY FOG
WILL DEVELOP PRIMARILY IN SOUTHEAST OREGON VALLEYS AND THE
LOWER TREASURE VALLEY IN IDAHO, WITH BRIEFLY LOWERED VISIBILITY
THROUGH THE EARLY MORNING. ABOVE NORMAL TEMPERATURES ARE
ANTICIPATED THE NEXT SEVERAL DAYS THANKS TO HIGH PRESSURE
CENTERING OVER THE INTERMOUNTAIN WEST. AIR STAGNATION CONCERNS
FROM TRAPPED POLLUTANTS WILL CONTINUE IN AREA VALLEYS THANKS TO
LIMITED MIXING AND LIGHT WINDS THROUGH THE WEEK. NO UPDATES
NECESSARY TO THE FORECAST.
AVIATION
VFR, EXCEPT MVFR/IFR IN PATCHY MIST IN LOWER BASINS AND
SHELTERED VALLEYS OVERNIGHT. SURFACE WINDS: VARIABLE UP TO 10 KT,
THEN NE-SE 5-15 KT WED AFTERNOON. WINDS ALOFT AT 10KFT MSL: W-NW 5-
15 KT, THEN VARIABLE BY WED/18Z.
KBOI...VFR. SURFACE WINDS: VARIABLE OR SOUTHEAST 3-7 KT.
AIR STAGNATION
NO QUESTION WE REMAIN LOCKED IN A STAGNANT
PATTERN INTO THE WEEKEND. MIXING LEVELS ARE FORECAST TO STAY AT
OR BELOW 1500 FEET AGL IN THE LOWER VALLEYS WITH LIGHT WINDS.
DRAINAGE WINDS IN THE SNAKE PLAIN (JEROME-GLENNS FERRY
CORRIDOR) WILL TOUCH 10-15 MPH AT TIMES, BUT OTHERWISE THERE IS
LITTLE MOVEMENT IN THE AIR MASS VERTICALLY OR HORIZONTALLY.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT...A WELL
ESTABLISHED UPPER HIGH WILL REMAIN CENTERED OVER THE INTERIOR
WEST THROUGH THURSDAY. THE SINKING AIR ALOFT WILL KEEP DRY AND
MILD WEATHER WEATHER IN PLACE ACROSS THE REGION AS AFTERNOON
TEMPERATURES REACH 10 DEGREES ABOVE NORMAL WED/THUR. SURFACE
WINDS REMAIN LIGHT DURING THE PERIOD AND THE RESULTING STAGNANT
AIR MASS SHOULD GRADUALLY REVEAL ITSELF THROUGH INCREASED
FOG/HAZE DURING THE WEEK, MOST NOTABLY ACROSS THE LOWER SNAKE
PLAIN AND BASINS/VALLEYS OF SE OREGON. THROUGH THURSDAY, FOG
FORMATION IN THE SNAKE PLAIN WILL BE LIMITED TO AREAS ALONG THE
SNAKE RIVER AND MORE BROADLY TO POINTS WEST OF THE CANYON/ADA
COUNTY LINE INTO THE WEISER BASIN. ADJUSTMENTS WERE MADE TO THE
NBM FORECAST LOWS AND TO INCREASE THE FOG COVERAGE ACROSS LOWER
VALLEYS EACH MORNING.
LONG TERM...FRIDAY THROUGH TUESDAY...THE UPPER LEVEL RIDGE THAT
DOMINATES THE SHORT-TERM PERIOD WILL BEGIN TO BREAKDOWN AND MOVE
EAST TO END THE WEEK. WHILE AT LEAST FRIDAY AND SATURDAY WILL
REMAIN DRY, ENSEMBLE CLUSTERS ARE IN GOOD AGREEMENT OF A PATTERN
CHANGE EARLY NEXT WEEK AS A TROUGH MOVES IN OFF THE COAST.
ALTHOUGH EXACT TIMING CAN'T BE PINNED DOWN QUITE YET,
DETERMINISTIC GUIDANCE ALL RESOLVE A COLD FRONT CROSSING OVER
OUR AREA COME LATE SUNDAY/EARLY MONDAY. THIS FRONT WILL BE WHAT
MIXES OUT OUR INVERSION WITH INCREASED WINDS AND COOLING ALOFT.
THE FRONT WILL ALSO COOL THE SURFACE TO MORE SEASONABLE
TEMPERATURES BY MONDAY. PRECIPITATION CHANCES WILL INCREASE
THROUGH THE DAY SUNDAY, BEFORE MAXING OUT MONDAY MORNING WITH A
55-75% CHANCE IN THE WEST CENTRAL MOUNTAINS AND A 35-55% CHANCE
ELSEWHERE. THESE CHANCES WILL LIKELY INCREASE IN THE DAYS TO
COME AS THE EXACT TIMING BECOMES BETTER RESOLVED. BEYOND MONDAY,
PRECIPITATION CHANCES WILL REMAIN NON-ZERO, AS ENSEMBLE
CLUSTERS REMAIN IN GOOD AGREEMENT OF TROUGHING OVER OUR AREA.
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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