509
FXUS65 KBOI 161706
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1006 AM MST SAT NOV 16 2024
DISCUSSION
MOSTLY CLEAR SKIES THIS MORNING WITH PATCHY FOG.
HIGH LEVEL CLOUDS ARE STREAMING IN FROM THE NORTHWEST AHEAD OF
THE NEXT WARM FRONT WITH INCREASING CLOUDS LATER TODAY. NEXT
WARM FRONT ARRIVES INTO EASTERN OR LATE THIS EVENING, WITH
PRECIPITATION REACHING SOUTHWEST ID BY SUNDAY MORNING. SNOW
LEVELS START AT THE VALLEY FLOORS, BUT WARM AIR ALOFT WILL
QUICKLY CHANGE SNOW OVER TO RAIN IN THE VALLEYS BELOW 5000 FEET
BY MIDDAY SUNDAY. SNOW LEVELS RISE TO 5000-7000 FEET ON SUNDAY
AFTERNOON AHEAD OF THE COLD FRONT. THERE IS A THREAT OF
FREEZING RAIN IN EASTERN OR AS THE TRANSITION OCCURS, BUT IT
WILL BE SHORT LIVED. THEN WINDS INCREASE ON SUNDAY AFTERNOON
AHEAD OF THE COLD FRONT. THE COLD FRONT MOVES THROUGH LATE
SUNDAY NIGHT INTO MONDAY MORNING WITH SNOW LEVELS FALLING TO THE
VALLEY FLOORS. PRECIPITATION QUICKLY SHUTS OFF BEHIND THE COLD
FRONT, SO ANY SNOW IN THE LOWER ELEVATIONS WILL BE A DUSTING AT
MOST. CURRENT FORECAST ON TRACK WITH NO UPDATES.
AVIATION
GENERALLY VFR, EXCEPT AREAS OF LOW STRATUS NEAR
KTWF/KJER. MOUNTAIN OBSCURATION. SURFACE WINDS: SW TO NW 5-15 KT.
GUSTS TO 20-30 KT FOR PORTIONS OF WESTERN SNAKE PLAIN. WINDS ALOFT
AT 10KFT MSL: W TO NW 10-20 KT.
KBOI...VFR. SURFACE WINDS: W-NW 10-15 KT, OCCASIONAL GUSTS TO 20-25
KT THROUGH THIS AFTERNOON. THEN, SE 5-10 KT AFTER SUN/01Z.
SUNDAY OUTLOOK...LOWERING BKN/OVC CEILINGS. RAIN/SNOW ARRIVING FROM
NW EARLY SUNDAY THROUGH EARLY MONDAY. MVFR TO LIFR IN PRECIPITATION
AND LOW CLOUDS. MOUNTAINS BECOMING OBSCURED. VARYING SNOW LEVELS
5000-7000FT MSL DURING THE DAY, LOWERING AT/NEAR VALLEY FLOORS
BY EARLY MONDAY. SURFACE WINDS: SE-SW 10-20 KT. AFTERNOON/EVENING
GUSTS GENERALLY 25- 35 KT, LOCALLY UP TO 40 KT.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH MONDAY NIGHT...MOSTLY CLEAR THIS
MORNING (EXCEPT FOR PATCHY VALLEY FOG) AS AN UPPER RIDGE PASSES
OVERHEAD. THE RIDGE WILL MOVE QUICKLY THROUGH OUR CWA TODAY AND
CLOUDS WILL INCREASE FROM THE NORTHWEST AS A STRONG STORM
APPROACHES FROM THE GULF OF ALASKA. NORTHWEST WINDS THIS MORNING
WILL CHANGE TO SOUTHEAST THROUGH SOUTHWEST 15 TO 25 MPH TONIGHT
AS THE STORM'S WARM FRONT APPROACHES. SNOW WILL BEGIN IN HARNEY
AND BAKER COUNTIES LATE TODAY, REACHING WESTERN ID BY MIDNIGHT,
AND SOUTH-CENTRAL ID SUNDAY AFTERNOON, EXCEPT RAIN BELOW 4000
FEET. THE SNOW LEVEL WILL RISE RAPIDLY EARLY SUNDAY MORNING
BEHIND THE WARM FRONT AND SNOW WILL CHANGE TO RAIN AS HIGH AS
7000 FEET MSL WITHIN 6-12 HOURS FOLLOWING THE FRONTAL PASSAGE.
COLDER VALLEYS IN EASTERN OREGON WILL HAVE A SLIGHT CHANCE OF
FREEZING RAIN EARLY SUNDAY MORNING JUST AHEAD OF THE WARM FRONT.
RAIN WILL CHANGE BACK TO SNOW SUNDAY NIGHT BEHIND THE STORM'S
COLD FRONT, WITH SNOW LEVEL LOWERING TO VALLEY FLOORS BY
SUNRISE MONDAY. WINDS WILL SHIFT TO NORTHWEST WITH GUSTS AS
HIGH AS 40 MPH BEHIND THE COLD FRONT. SNOW SHOWERS WITH
MINOR ACCUMULATION WILL LINGER MONDAY. TOTAL PCPN FROM THIS
EVENING THROUGH EARLY TUESDAY MORNING WILL BE 0.75 TO 1.25
INCH IN NORTHERN AREAS, WITH UP TO A FOOT OF SNOW ON HIGHER
PEAKS. BUT AT THE 5000 FOOT LEVEL, E.G., NEAR MCCALL, ID,
TOTAL SNOWFALL WILL BE NEAR 6 INCHES. MUCH LESS PCPN WILL
FALL IN SOUTHEAST OREGON AND IN IDAHO FROM THE SNAKE BASIN
SOUTHWARD -- GENERALLY LESS THAN 0.25 INCH, EXCEPT UP TO 0.50
INCH ON THE MOUNTAINS. SNOWFALL IN THE SNAKE BASIN WILL RANGE
FROM A DUSTING IN THE TREASURE VALLEY TO A HALF INCH IN THE
MAGIC VALLEY.
LONG TERM...TUESDAY THROUGH SATURDAY...SNOW SHOWERS WILL
TAPER OFF FROM WEST TO EAST TUESDAY AS BRIEF, DRY HIGH PRESSURE
DEVELOPS. TEMPERATURES WILL BE COOLER THAN MONDAY, PEAKING
AROUND 5-10 DEGREES BELOW NORMAL. A SIGNIFICANT ATMOSPHERIC
RIVER IS FORECAST TO ARRIVE WEDNESDAY, SPREADING A HEALTHY
PLUME OF MOISTURE INTO MUCH OF EASTERN OREGON AND WEST-CENTRAL
IDAHO THROUGH AT LEAST FRIDAY. AREAS FARTHER SOUTH NEAR THE NV
BORDER HAVE LESS OF A CHANCE OF PRECIPITATION (10-20%), WHILE
THE PERSISTENT UPSLOPE PATTERN FAVORS THE WEST-CENTRAL
IDAHO/BOISE MOUNTAINS (GREATER THAN 60% CHANCE). SNOW LEVELS
WILL CLIMB EACH DAY IN THIS WEST-SOUTHWESTERLY FLOW, BEGINNING
AROUND 3500-5500 FT MSL WEDNESDAY AND RISING TO 6500-7500 FT
MSL THURSDAY/FRIDAY. FOR THOSE HIGH ELEVATIONS, SNOW TOTALS
COULD POTENTIALLY BE SIGNIFICANT DUE TO THIS MULTI-DAY PRECIP
EVENT. FOR THE TERRAIN BELOW THE SNOW LEVEL, MODERATE TO HEAVY
RAINFALL TOTALS MAY CREATE CONCERNS FOR RECENT BURN SCARS.
MID-LEVEL WIND SPEEDS WILL ALSO BE NOTABLE, WHICH COULD
TRANSFER DOWN TO THE MOUNTAINS AT TIMES. THERE IS SOME
INDICATION IN THE MODELS THAT THE UPPER FLOW WILL BECOME
MORE SOUTHERLY ON SATURDAY, PROMPTING THE PLUME OF MOISTURE
TO MOVE NORTHWARD (TEMPORARILY OUT OF THE FORECAST AREA).
HIGH TEMPERATURES WILL RISE SEVERAL DEGREES ABOVE NORMAL BY
THURSDAY.
BOI WATCHES/WARNINGS/ADVISORIES
ID...NONE.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.TWITTER.COM/NWSBOISE
DISCUSSION...KA
AVIATION.....SP
SHORT TERM...LC
LONG TERM....SH
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