383
FXUS65 KBOI 220238
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
838 PM MDT TUE OCT 21 2025
DISCUSSION
A RIDGE WILL REMAIN OVER THE REGION FOR THE NEXT
SEVERAL DAYS WITH A WARMING TREND THROUGH FRIDAY, WITH MILD
TEMPERATURES DURING THE DAY AND COOL TEMPERATURES AT NIGHT. THE
RIDGE BREAKS DOWN ON SATURDAY WITH A FRONTAL SYSTEM APPROACHING
FROM THE NORTHWEST. THE SHOWERS INCREASE AHEAD OF THE COLD FRONT
ON SATURDAY, WITH THE FRONT MOVING THROUGH SOMETIME ON SUNDAY
INTO MONDAY. NO UPDATES.
AVIATION
VFR. PATCHY FOG OVERNIGHT. SURFACE WINDS: VARIABLE
LESS THAN 10 KT. WINDS ALOFT AT 10KFT MSL: W-SW 5-15 KT.
KBOI...VFR. SURFACE WINDS: SE 5-10KT BECOMING VARIABLE 5KT
WED AFTERNOON.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT...WEAK UPPER-LEVEL
RIDGING IS IN PLACE ACROSS THE REGION TODAY. THE RIDGING WILL
CONTINUE TO BE WEAK THROUGH THE PERIOD, AS AN UPPER-LEVEL CUTOFF
LOW WILL MOVE INLAND FROM THE CALIFORNIA COAST INTO THE DESERT
SOUTHWEST. MODELS KEEP IT FAR ENOUGH SOUTH OF THE REGION TO
LIMIT IMPACTS, WITH A TRANSITION TO WEAK UPPER-LEVEL FLOW
WEDNESDAY AND ANOTHER SHORTWAVE UPPER-LEVEL RIDGE BUILDING IN
THURSDAY. AS THE UPPER-LEVEL LOW MOVES INTO THE FOUR CORNERS
REGION THURSDAY, THE SURFACE WINDS BETWEEN MOUNTAIN HOME AND THE
WESTERN MAGIC VALLEY WILL INCREASE OUT OF THE W/NW WITH AN
INCREASED PRESSURE GRADIENT.
THIS PATTERN IS PLACING THE AREA IN A WARMING TREND WITH HIGH
TEMPERATURES RISING FROM NEAR NORMAL TODAY TO 5 DEGREES ABOVE
NORMAL BY THURSDAY. DAILY LOW TEMPERATURES WILL ALSO RISE OVER
THE PERIOD, GOING FROM NEAR NORMAL TODAY TO 5 DEGREES ABOVE
NORMAL BY THURSDAY NIGHT. WHILE THIS WILL CAUSE LOWER ELEVATION
VALLEY MINIMUM TEMPERATURES TO HOVER IN THE MID-TO-HIGH 30S, NO
ADDITIONAL FROST OR FREEZE WARNINGS WILL BE ISSUED IN 2025.
LONG TERM...FRIDAY THROUGH TUESDAY...ON FRIDAY, THE AREA WILL
START UNDER A SHORTWAVE RIDGE PATTERN WITH AN IMPINGING UPPER-
LEVEL LONGWAVE TROUGH SYSTEM AND ASSOCIATED ATMOSPHERIC RIVER.
WHILE THIS INTENSE UPPER-LEVEL LOW SPINS IN GULF OF ALASKA (AND
SLOWLY MOVES ONSHORE INTO BRITISH COLUMBIA), MULTIPLE EMBEDDED
SHORTWAVES IN THE SOUTHWESTERLY FLOW ALOFT WILL CREATED ENHANCED
CONDITIONS FOR PRECIPITATION THROUGH THE WEEKEND. AN ASSOCIATED
COLD FRONT WILL MOVE THROUGH THE AREA WITH THESE EMBEDDED
SHORTWAVES, HOWEVER EXACT TIMING ON THIS SEEMS TO KEEP GETTING
PUSHED LATER AND LATER. PRECIPITATION CHANCES INCREASE WEST-TO-
EAST FRIDAY NIGHT, EVENTUALLY BECOMING WIDESPREAD 50% CHANCE OR
GREATER SATURDAY NIGHT THROUGH SUNDAY NIGHT. AREAS OF 75% CHANCE
OR GREATER WILL EXIST DURING THIS SAME PERIOD FOR HIGHER
ELEVATION AREAS. PRECIPITATION CHANCES CONTINUE INTO MONDAY,
HOWEVER, LONG RANGE MODELS CURRENTLY DISAGREE ON WHEN THE ROUNDS
OF EMBEDDED SHORTWAVES AND ASSOCIATED MOISTURE MAKE THEIR WAY
FULLY THROUGH THE AREA.
WARM SOUTHWEST FLOW AHEAD OF THE MAIN COLD AIR MASS WILL KEEP
TEMPERATURES ABOVE NORMAL ON FRIDAY AND SATURDAY. TEMPERATURES
WILL THEN PLUMMET 10 TO 15 DEGREES ON SUNDAY AS COLD AIR,
GUSTY WINDS, AND SIGNIFICANT MOISTURE MOVES INTO THE REGION.
SNOW LEVELS WILL BE AROUND 7000-8000 FEET MSL THROUGH MIDDAY
SATURDAY, DROPPING TO 4000- 5000 FEET MSL ON SUNDAY AND MONDAY.
WIDESPREAD VALLEY RAIN AND HEAVY MOUNTAIN SNOW IS ANTICIPATED,
WITH 2 DAY SNOWFALL TOTALS REACHING UP TO 8 TO 12 INCHES FOR
HIGHER SUMMITS WITH 1-3 INCHES FOR MOUNTAIN VALLEYS BY MONDAY
MORNING.
BY LATE MONDAY, SOME LINGERING MOISTURE WILL MOVE THROUGH THE
REGION AND NORTHWESTERLY FLOW WILL SET IN. TEMPERATURES WILL
REMAIN COOL AND WILL BEGIN TO DRY OUT LATE MONDAY. ON TUESDAY,
AN UPPER-LEVEL RIDGE WILL START TO BUILD IN, STARTING TO RISE
TEMPERATURES ONCE AGAIN.
PRELIMINARY POINT TEMPS/POPS
BAKER CITY 27 63 28 62 / 0 0 0 0
BOISE 39 63 40 64 / 0 0 0 0
BURNS 23 64 25 64 / 0 0 0 0
CALDWELL 34 64 36 65 / 0 0 0 0
FAIRFIELD 27 61 28 62 / 0 0 0 0
IDAHO CITY 29 66 29 65 / 0 0 0 0
JEROME 36 62 38 60 / 0 0 0 0
MCCALL 29 59 29 57 / 0 0 0 0
MOUNTAIN HOME 34 66 36 65 / 0 0 0 0
ONTARIO 31 61 34 65 / 0 0 0 0
ROME 29 64 32 66 / 0 0 0 0
TWIN FALLS 32 61 38 61 / 0 0 0 0
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...KA
AVIATION.....KA
SHORT TERM...CH
LONG TERM....CH
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