130
FXUS65 KBOI 181057
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
357 AM MST THU DEC 18 2025
SHORT TERM...TODAY THROUGH SATURDAY NIGHT
NEXT PACIFIC SYSTEM
IS ON OUR DOORSTEP THIS MORNING WITH A NICE STREAM OF MOISTURE
EXTENDING ALL THE WAY TO HAWAII. PRECIPITATION IS MOVING ACROSS
CENTRAL OR THIS MORNING AND WILL BECOME WIDESPREAD OVER
SOUTHEAST OR AND SOUTHWEST ID THIS MORNING AS A WARM FRONT LIFTS
NORTHWARD. COOL AIR REMAINS OVER THE AREA FROM THE COLD FRONT
YESTERDAY, AND SNOW LEVELS ARE AT THE SURFACE THIS MORNING. AS
THE WARM FRONT LIFTS NORTHWARD OVER THE AREA, SNOW LEVELS WILL
QUICKLY RISE TO 7000-8000 FEET BY THIS AFTERNOON OVER THE
SOUTHEAST OR BASINS, AND SNAKE PLAIN SOUTH. SNOW LEVELS WILL
REMAIN LOWER OVER THE CENTRAL ID MOUNTAINS AND THE LOWER
TREASURE VALLEY TO BAKER COUNTY THROUGH THIS AFTERNOON BEFORE
WARMER AIR MIXES DOWN TO THE SURFACE. BAKER COUNTY COULD SEE
MODERATE TO HEAVY SNOW AROUND MIDDAY FOR A BRIEF PERIOD AS THE
WARM FRONT LIFTS NORTHWARD. HALFWAY MAY SEE MORE SNOW THAN
FORECAST DUE TO THE POOR HANDLING OF COOL AIR IN THE LOWER
ELEVATIONS. SNOW LEVELS WILL REMAIN LOWER AROUND THE WALLOWAS,
HELLS CANYON, AND AROUND MCCALL UNTIL THE LATE EVENING BEFORE
RISING TO AROUND 6000-7000' MSL AS COOLER AIR WILL HOLD ON
LONGER THAN THE REST OF THE AREA. SNOW AMOUNTS OF 6 TO 10 INCHES
POSSIBLE ON THURSDAY ABOVE 6500' MSL. GENERALLY 2 TO 4 INCHES
IN THE MOUNTAIN VALLEYS OF THE WEST CENTRAL AND BOISE MOUNTAINS,
CAMAS PRAIRIE AND BAKER COUNTY. NORTHERN HARNEY AND MALHEUR
COUNTY COULD SEE 1 TO 3 INCHES. AS THE WARM FRONT LIFTS
NORTHWARD, WINDS INCREASE DRAMATICALLY ACROSS SOUTHERN HARNEY
AND MALHEUR COUNTIES, AND SOUTH OF THE SNAKE BASIN IN IDAHO.
WINDS ALOFT WILL BE STRONG DURING THIS TIME AND PRECIPITATION
WILL BE FAVORED OVER THE CENTRAL ID MOUNTAINS. ON FRIDAY, WINDS
ALOFT BECOME STRONG AGAIN, WITH PRECIPITATION BECOMING FOCUSED
OVER THE MOUNTAINS, WITH GENERALLY DRY CONDITIONS IN THE SNAKE
BASIN. A WIND ADVISORY HAS BEEN ISSUED FOR SOUTHERN HARNEY AND
MALHEUR COUNTIES AND SOUTH OF THE SNAKE PLAIN IN IDAHO.
TEMPERATURES WILL BE 15-20 DEGREES ABOVE NORMAL ON FRIDAY IN THE
WARM SECTOR OF THE SYSTEM. A COLD FRONT ORIENTED FROM WEST TO
EAST OVER NORTHERN OR AND CENTRAL ID WILL SLOWLY MOVE SOUTH OVER
THE DAY ON FRIDAY. SNOW LEVELS WILL BE AROUND 7000-8000' ON
FRIDAY SOUTH OF BOISE TO BURNS OR AND AROUND 5500' MSL NEAR
BAKER AND MCCALL. SNOW LEVELS FALL TO THE VALLEY FLOORS NEAR
BAKER AND MCCALL BY FRIDAY NIGHT AS THE FRONT MOVES SOUTH.
SIGNIFICANT SNOW ACCUMULATIONS WILL BE CONFINED TO THE HIGHEST
PEAKS ABOVE 7000' MSL UNTIL THE COLD FRONT MOVES SOUTH. AS THE
FRONT STARTS TO MOVE SOUTH, SNOW LEVELS FALL TO THE VALLEY
FLOORS AS THE PRECIPITATION SHUTS OFF BEHIND THE FRONT, SO A
WINTRY MIX POSSIBLE. TEMPERATURES SATURDAY LOWER TO AROUND 5-10
DEGREES ABOVE NORMAL. SATURDAY WILL FEATURE A 10-20 PERCENT
CHANCE OF SNOW BUT THE MODELS ARE TRENDING TOWARD A DRY DAY ON
SATURDAY.
LONG TERM...SUNDAY THROUGH THURSDAY
BEGINNING SUNDAY,
INCREASED SOUTHWEST FLOW ALOFT AHEAD OF A DEEP TROUGH OFF THE
COAST WILL BRING A PLUME OF SUBTROPICAL MOISTURE INTO SE OREGON
AND SW IDAHO. THE INITIAL ARRIVAL OF MOISTURE IS EXPECTED SUNDAY
MORNING INTO SUNDAY NIGHT, AS A WARM FRONT MOVES NORTH THROUGH
THE AREA AND BRINGS WIDESPREAD PRECIPITATION. SNOW LEVELS WILL
BEGIN AROUND 3000-5000 FT MSL FOR THE NORTH AND 6000-7000 FT MSL
FOR SOUTH, THEN RISE THROUGHOUT THE DAY. MODERATE TO HEAVY
PRECIPITATION TOTALS ARE LIKELY WITH THIS EVENT, BUT SIGNIFICANT
SNOWFALL WILL BE LIMITED TO HIGH ELEVATIONS. STRONG SOUTHWEST
FLOW ALOFT WILL CONTINUE ON MONDAY, BRINGING ADDITIONAL MOISTURE
ESPECIALLY TO THE MOUNTAINS. SNOW LEVELS ARE SOMEWHAT UNCERTAIN
DUE TO THE TROUGH MOVING SLOWLY INLAND. ON TUESDAY AND
WEDNESDAY, THE FLOW ALOFT IS EXPECTED TO BECOME MORE SOUTHERLY
AS THE TROUGH DEEPENS OFF THE COAST. THIS WILL KEEP OUR AREA
MILD WITH A 25-50% CHANCE OF RAIN AND HIGH ELEVATION SNOW ON
TUESDAY, INCREASING TO A 35-75% CHANCE ON WEDNESDAY. HOWEVER,
SLIGHT ADJUSTMENTS IN THE POSITION OF THE TROUGH COULD ADJUST
TEMPERATURES HIGHER OR LOWER. THIS PATTERN WILL PERSIST FOR
THURSDAY, WITH PERIODS OF PRECIPITATION AND MEDIUM TO HIGH SNOW
LEVELS CONTINUING.
AVIATION
SNOW OR WINTRY MIX MOVING IN FROM SW TO NE AFTER
THU/12Z. TRANSITIONING TO RAIN BELOW 5K-8K FEET BY LATE AM/AFTERNOON
AS PRECIP MOVES NE. REMAINING SNOW/MIX FOR W-CNTRL ID/BOISE MOUNTAIN-
VALLEYS UNTIL EVE. VFR-MVFR IN RAIN, MVFR-LIFR IN SNOW. MOUNTAINS
OBSCURED. SURFACE WINDS: VARIABLE UP TO 12 KT. THEN SW-SE 10-25 KT
WITH GUSTS OF 25-45 KT THU PM, STRONGEST WEST/SOUTH OF SNAKE PLAIN.
LOCALLY HIGHER GUSTS ON MTN TOPS. WINDS ALOFT AT 10KFT MSL: W 20-30
KT, THEN W-SW 40-75 KT BY THU/18Z.
KBOI...VFR EARLY AM, THEN PRECIP BEGINNING AROUND THU/15Z-17Z. A 25%
CHANCE OF INITIAL WINTRY MIX, BEFORE ALL RAIN AFTER THU/19Z. NO SNOW
ACCUM EXPECTED. MVFR IN RAIN, BRIEF IFR IN WINTRY MIX. SURFACE
WINDS: SE AROUND 10KT, THEN SE 12-18 KT WITH GUSTS 25-35 KT LATE
MORNING/AFTERNOON. RAIN TAPERS OFF AROUND FRI/00Z.
WEEKEND OUTLOOK...COLD FRONT FRIDAY WITH PRECIP MOVING FROM N TO S.
MTNS OBSCURED. SNOW LEVELS 3K-5K FT MSL FOR NORTH, 5K-7KFT FOR
SOUTH, LOWERING BY FRI NIGHT. IFR/LIFR IN SNOW, VFR/MFR IN RAIN.
SHOWERS TAPERING OFF SAT, LINGERING MTN OBSCURATION AND PATCHY AM
FOG. WIDESPREAD RAIN/SNOW SUNDAY. SNOW LEVELS 3K-5KFT MSL TO NORTH,
6K-7KFT TO SOUTH, RISING THROUGHOUT DAY. MTNS OBSCURED. SURFACE
WINDS FRI: SW-SE 15-30 KT, GUSTS 25-45 KT, EXCEPT 50-55 KT ON MTN
TOPS. SAT: SW-SE 5-15 KT. SUN: SW-SE 10-20 KT, GUSTS 20-35 KT.
BOI WATCHES/WARNINGS/ADVISORIES
ID...WIND ADVISORY FROM 5 AM TO 5 PM MST FRIDAY IDZ015-029-030.
OR...WIND ADVISORY FROM 5 AM MST /4 AM PST/ TO 5 PM MST /4 PM PST/
FRIDAY ORZ061-063.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
SHORT TERM...KA
LONG TERM....SH
AVIATION.....SH
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