270
FXUS65 KBOI 052139
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
239 PM MST MON JAN 5 2026
SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT
PRECIPITATION
CONTINUING ACROSS OUR AREA, AS OF WRITING THIS, AS AN UPPER
LEVEL SHORTWAVE MOVES EAST OF OUR AREA. WITH A LOW CLOSING OFF
OF THE WEST COAST, THE BETTER DYNAMICS OF THIS TROUGH WILL BE
FOUND OVER OUR MOUNTAIN ZONES; OROGRAPHIC LIFT WILL ALSO AID IN
PRECIPITATION PRODUCTION. WHILE THE AREA WILL DRY OUT WITHIN AND
SOUTH/WEST OF THE SNAKE RIVER PLAIN, THE CENTRAL IDAHO MOUNTAINS
WILL HAVE SNOW SHOWERS THROUGH THE MAJORITY OF THE PERIOD.
THE FUN PICKS BACK UP AGAIN TUESDAY AFTERNOON THROUGH WEDNESDAY.
COME TUESDAY AFTERNOON, A TROUGH WILL DIG DOWN ACROSS OUR AREA
OUT OF NORTHWESTERLY FLOW. AS THIS TROUGH DIGS, MID-LEVEL WINDS
SWITCH TO BE OUT OF THE WEST, WITH SPEEDS OF 30-50 KNOTS AT
700MB. THIS ORIENTATION IS FAVORABLE OUR MOUNTAIN ZONES TO GET
GOOD OROGRAPHIC ENHANCEMENT OF PRECIPITATION. HAVE EXPANDED AND
EXTENDED THE WINTER WEATHER ADVISORY TO NOW INCLUDE THE BOISE
MOUNTAIN ZONE. THE ADVISORY IS NOW VALID FROM TUESDAY AFTERNOON
THROUGH LATE WEDNESDAY, WHEN THE HIGHEST SNOWFALL RATES OCCUR
(KEEPING IN MIND IT WILL ALSO SNOW OUTSIDE OF THE ADVISORY
WINDOW). THE LONG VALLEY OF IDAHO WILL SEE BETWEEN 5-10 INCHES
OF SNOW, WITH 10 TO 20 INCHES ABOVE 6000 FEET MSL. MOUNTAIN
VALLEYS IN THE BOISE MOUNTAIN ZONE WILL SEE 3-7 INCHES, WITH
12-18 INCHES ABOVE 6000 FEET MSL. GUSTY WINDS WILL ALSO CREATE
LOCALIZED BLOWING/DRIFTING SNOW IN MOUNTAIN VALLEYS.
PRECIPITATION WILL INCREASE AREA WIDE THROUGH WEDNESDAY AS A
COLD FRONT CROSSES ACROSS THE AREA. WHILE THE SNAKE RIVER PLAIN
WILL INITIALLY JUST SEE RAIN WEDNESDAY, WITH SNOW LEVELS AT
4-5KFT MSL, PRECIPITATION WILL BEGIN TO CHANGE OVER TO A WINTRY
MIX/SNOW AS SNOW LEVELS DROP TO VALLEY FLOORS WITH A EXTRA SURGE
OF COLD AIR AND PERHAPS A SECONDARY COLD FRONT WEDNESDAY
AFTERNOON. BY THURSDAY MORNING, SNOW WILL CONTINUE IN THE
MOUNTAIN ZONES WITH THIS LITTLE EXTRA PUSH OF FORCING AND
MOISTURE, AND FLURRIES IN THE LOWER SNAKE RIVER PLAIN. THE
WESTERN MAGIC VALLEY COULD SEE AROUND A HALF AN INCH OF
ACCUMULATION THURSDAY MORNING. ALTHOUGH AT THAT POINT
PRECIPITATION CHANCES WILL BE ON THE DECLINE ON THE BACKSIDE OF
THE DEPARTING TROUGH.
LONG TERM...THURSDAY THROUGH MONDAY...THE PERIOD WILL START OUT
ACTIVE WITH SHOWERS AND BREEZY CONDITIONS ON THURSDAY AS THE REGION
IS POSITIONED ON THE BACKSIDE OF AN EASTWARD MOVING TROUGH. ANY
CHANCE OF LIGHT SNOW AT LOWER ELEVATIONS WILL CLOSE DOWN BY THURSDAY
AFTERNOON AS SHOWERS RETREAT TO THE MOUNTAINS. AN UPPER RIDGE IS
QUICK TO BUILD IN FROM THE COAST FRI/SAT, BRINGING DRIER WEATHER.
DETERMINISTIC MODELS HAVE INTRODUCED SOME UNCERTAINTY FOR THE
WEEKEND AS SOLUTIONS SHOW A SHORTWAVE TROUGH SNEAKING INTO THE PAC
NW ON SUNDAY. IT WOULDN'T BRING MUCH PRECIPITATION, BUT IF
STRONG/COLD ENOUGH IT COULD BREAK THROUGH THE DEVELOPING TEMPERATURE
INVERSION. THAT'S A DETAIL WE'LL KEEP AN EYE, BUT OVERALL THE REGION
IS DRY THIS WEEKEND INTO NEXT WEEK, WITH TEMPERATURES WARMING IN THE
MOUNTAINS WHILE VALLEY TEMPERATURES LAG. DEVELOPMENT OF AN INVERSION
WOULD ALSO INTRODUCE THE POTENTIAL FOR VALLEY FOG/STRATUS.
AVIATION
PERIODS OF RAIN AND SNOW WILL PRODUCE IFR CONDITIONS IN
THE MTNS TONIGHT AND TUESDAY. VALLEYS ARE MOSTLY VFR WITH LOCAL MVFR
CEILINGS. MOUNTAINS WILL BE OBSCURED BY LOW CEILINGS AND SNOW WITH
SNOW LEVELS 4000-5000 FEET MSL. POSSIBLE IFR IN LOW STRATUS/PATCHY
FOG DEVELOPING TUESDAY MORNING IN THE SNAKE PLAIN WEST OF KEUL.
SURFACE WINDS: SE-SW 5-15 KT, GUSTS TO 25 KT ACROSS THE HIGHER
TERRAIN AND SE OREGON THROUGH 03Z. WINDS ALOFT AT 10KFT MSL: SW 20-
30 KT BECOMING W 25-40 KT AFTER 12Z TUESDAY.
KBOI...VFR WITH SCATTERED RAIN SHOWERS MAINLY THROUGH THIS EVENING.
MVFR CEILINGS POSSIBLE WITH PRECIPITATION. LIGHT SE SURFACE WINDS,
WITH RAIN PRODUCING BRIEF SHIFTS TO THE W-NW.
BOI WATCHES/WARNINGS/ADVISORIES
ID...WINTER WEATHER ADVISORY FROM 2 PM TUESDAY TO 11 PM MST
WEDNESDAY IDZ011-013.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
SHORT TERM...NF
LONG TERM....DG
AVIATION.....DG
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