887
FXUS65 KBOI 280228
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
828 PM MDT MON OCT 27 2025
DISCUSSION
LIGHT SNOW OVER THE WEST-CENTRAL IDAHO MOUNTAINS
HAS DIMINISHED THIS EVENING, THOUGH LOW CLOUDS IN THIS AREA
WILL PERSIST UNTIL TUESDAY MORNING. FORECAST CONFIDENCE IN
MOUNTAIN VALLEY FOG DEVELOPMENT IS FAIRLY LOW OVERNIGHT DUE TO
DRIER AIR MASS WITH LOWER DEWPOINTS. TEMPERATURES WILL REACH
AT/BELOW FREEZING BY TUESDAY MORNING FOR MOST LOCATIONS,
SUPPORTED BY MOSTLY CLEAR SKIES, LOWER DEWPOINTS, AND A COLD
AIR MASS IN PLACE. NO UPDATES TO CURRENT FORECAST.
AVIATION
VFR, EXCEPT MOUNTAIN OBSCURATION FROM LOW CEILINGS
IN THE W-CENTRAL IDAHO TERRAIN. LOW FORECAST CONFIDENCE (<10%)
FOR MOUNTAIN-VALLEY FOG DEVELOPMENT OVERNIGHT. SURFACE WINDS:
VARIABLE 10 KT OR LESS, THEN NE TO SE 5-15 KT TUE AFTERNOON.
AFTERNOON GUSTS AROUND 20 KT AT KBKE, AND FROM KEUL TO KJER.
KBOI...VFR AND MOSTLY CLEAR. FREEZING TEMPERATURES EXPECTED
TUE MORNING. SURFACE WINDS: SE 5-12 KT. OCCASIONAL GUSTS TO
AROUND 15-20 KT BETWEEN TUE/18Z TO WED/00Z.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT...DRY WEATHER
WILL PREVAIL THROUGH THE PERIOD AS AN UPPER RIDGE BUILDS IN FROM
THE COAST OVER THE NEXT DAY. TONIGHT IS THE COLDEST NIGHT AHEAD,
WITH A HARD FREEZE POSSIBLE ACROSS ALL ZONES. RECENT
PRECIPITATION WILL FEED FOG DEVELOPMENT IN MORE SHELTERED MTN
VALLEYS, WHILE AN EASTERLY WIND ACROSS OPEN TERRAIN PROVIDES
ENOUGH MIXING TO SUPPRESS FOG/STRATUS DEVELOPMENT. WARMING
ALOFT WILL BEGIN TO BUILD AN INVERSION AS MIXING IS LIMITED BY
THE LATE OCTOBER SUN ANGLE. AN UPPER TROUGH RIDING THROUGH THE
RIDGE WILL INCREASE CLOUDS ON WEDNESDAY, BUT WE REMAIN DRY AS
IT'S DEFLECTED TO OUR NORTH. VALLEY TEMPERATURES WILL BE SLOWER
TO RESPOND TO THE WARMING ALOFT AND REMAIN BELOW NORMAL THROUGH
WEDNESDAY WHILE MTN SITES RETURN TO NORMAL.
LONG TERM...THURSDAY THROUGH MONDAY...INCREASING CLOUD COVER ON
THURSDAY AS A DEEP ALASKAN LOW KICKS UP AN ATMOSPHERIC RIVER
THAT WILL IMPACT THE PACNW AND CANADIAN WEST COAST. OUR FORECAST
AREA IS SPARED MOST OF THE PRECIPITATION UNTIL SATURDAY NIGHT.
WE ARE CURRENTLY FORECASTING A 20-40% CHANCE OF PRECIPITATION IN
THE NORTH INCLUDING VALLEY AND BAKER COUNTIES, THOUGH MODELS
DISAGREE ON WHERE THE NARROW BAND OF MOISTURE WILL POSITION
ITSELF. AMONGST DETERMINISTIC MODELS, WE RANGE FROM DRY IN THE
GFS TO STEADY RAIN SHOWERS IN THE CANADIAN. PRECIPITATION MAY
SLOWLY MOVE SOUTH SUNDAY. THE WEEKEND WILL ALSO BE BREEZY AS THE
PRESSURE GRADIENT TIGHTENS. A RIDGE BUILDS BACK IN TO THE ARE
SUNDAY NIGHT. TEMPERATURES WILL BE SEASONABLE FOR THIS TIME OF
YEAR, ALTHOUGH WILL LEAN ABOVE NORMAL OVER THE COMING WEEKEND.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...SH
AVIATION.....SH
SHORT TERM...DG
LONG TERM....JM
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