601
FXUS65 KBOI 050918
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
218 AM MST THU FEB 5 2026
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
UPPER LEVEL RIDGE
AND THE INVERSION IN THE VALLEYS WILL BE AT MAXIMUM STRENGTH
TODAY OVER OUR CWA. NEAR-RECORD HIGH TEMPS ARE EXPECTED AGAIN
TODAY AND FRIDAY EVEN IN THE INVERSION AREAS. THE MAIN RIDGE
WILL SHIFT EAST OF OUR CWA TONIGHT THROUGH SUNDAY. A PACIFIC
UPPER LOW MOVING INLAND ACROSS THE SWRN US WILL SLIGHTLY WEAKEN
THE RIDGE AS FAR NORTH AS OUR AREA FRIDAY NIGHT AND SATURDAY,
BUT IT WILL REBUILD LATER SATURDAY IN OREGON, AND SATURDAY
NIGHT IN IDAHO. HIGHER ELEVATIONS WILL COOL SLIGHTLY SATURDAY
BUT THE VALLEYS WILL FEEL NOTHING FROM THE PASSING LOW.
LONG TERM...SUNDAY THROUGH THURSDAY
THE UPPER RIDGE WILL
FLATTEN SUNDAY AS A NORTH PACIFIC COLD FRONT AND SUPPORTING
UPPER TROUGH MOVE ONTO THE NORTHWEST COAST. THE FRONT WILL REACH
OUR CWA LATE SUNDAY NIGHT AND MONDAY MORNING WITH RAIN AND SNOW
SHOWERS, GUSTY NORTHWEST WINDS, AND MUCH COOLER AIR ESPECIALLY
ALOFT. THE COOLING WILL WEAKEN THE INVERSION IN THE UNDERLYING
VALLEYS. WINDS ALONG AND BEHIND THE COLD FRONT SHOULD EASILY BE
ABLE TO CLEAR THE STAGNANT AIR FROM THE VALLEYS. TUESDAY THROUGH
THURSDAY WILL FINALLY COOL TO SEASONABLE TEMPERATURES. THERE
WILL STILL BE ENOUGH MOISTURE FOR A 30 TO 50 PERCENT CHANCE OF
SNOW SHOWERS IN THE MOUNTAINS, BUT OVERALL THOSE DAYS LOOK DRIER
THAN MONDAY.
AVIATION
GENERALLY VFR. PATCHY MVFR-IFR VISIBILITY FROM
HAZE/MIST IN LOWER BASINS AND SHELTERED VALLEYS EARLY 05/16Z.
SURFACE WINDS: VARIABLE LESS THAN 10 KT, EXCEPT E-NE 10-15 KT
IN S-CENTRAL IDAHO. AFTER 05/16Z NE-SE WIND EXPECTED IN
ALL AREAS. WINDS ALOFT AT 10KFT MSL: VARIABLE 5-15 KT.
KBOI...VFR. SURFACE WINDS: SE 3-9 KT UNTIL 05/18Z THEN LIGHT
AND VARIABLE.
WEEKEND OUTLOOK...CONTINUED VFR, EXCEPT LOCAL IFR IN THE
VALLEYS IN THE MORNINGS DUE TO FOG/STRATUS.
AIR STAGNATION
LITTLE AIR MOVEMENT IN THE VALLEYS THROUGH
SUNDAY DUE TO AN INVERSION THAT WILL CONTINUE UNDER STRONG HIGH
PRESSURE ALOFT. A PACIFIC COLD FRONT AND SUPPORTING UPPER
TROUGH WILL ARRIVE LATE SUNDAY NIGHT THROUGH MONDAY MORNING
TO FINALLY BREAK THE INVERSION, SCOUR THE STAGNANT AIR, AND
GREATLY INCREASE VERTICAL MIXING.
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
SHORT TERM...LC
LONG TERM....LC
AVIATION.....LC
AIR STAGNATION...LC
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