750
FXUS65 KBOI 210451
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
951 PM MST FRI DEC 20 2024
DISCUSSION
HIGH CLOUDS ARE STREAMING IN FROM A STORM OFF THE
WEST COAST. THIS WILL LIMIT FOG DEVELOPMENT TONIGHT. A WEAK WAVE
BREAKS THROUGH THE RIDGE ON SATURDAY AFTERNOON, WITH SCATTERED
SHOWERS DURING THE AFTERNOON AND EVENING. MINIMAL PRECIPITATION
ACCUMULATIONS WITH THIS SYSTEM. SNOW LEVELS WILL GENERALLY BE
6000-8000 FEET ON SATURDAY WITH THE EXCEPTION OF THE LOWER
TREASURE VALLEY AND BAKER COUNTY WHERE SNOW LEVELS OF 4000-6000
FEET EXPECTED. SUNDAY WILL GENERALLY BE DRY BEFORE ANOTHER
SYSTEM MOVES INTO THE AREA ON MONDAY. NO UPDATES.
AVIATION
VFR. PATCHY LIFR FOG TONIGHT, BUT HIGH CLOUDS SHOULD
LIMIT FOG. SURFACE WINDS: VARIABLE LESS THAN 10 KT, EXCEPT
EASTERLY 10-20 KT NEAR KJER/KMUO. WINDS ALOFT AT 10KFT MSL:
W-SW 15- 25 KT. AREAS OF LLWS ON SATURDAY MORNING.
KBOI...VFR. LIGHT SURFACE WINDS BECOMING SE 10-20KT SAT
AFTERNOON.
WEEKEND OUTLOOK...LIGHT VALLEY RAIN AND MOUNTAIN SNOW WILL MOVE WEST
TO EAST LATE ON SATURDAY. A BRIEF BREAK IN PRECIPITATION IS EXPECTED
LATE SATURDAY NIGHT INTO SUNDAY MORNING BEFORE MORE RAIN AND SNOW
ARRIVE LATE SUNDAY. MVFR TO LIFR IN PRECIPITATION WITH SNOW LEVELS
GENERALLY 4000-7000 FT MSL, SNOW LEVELS HIGHER ON SATURDAY.
MOUNTAINS OBSCURED. SURFACE WINDS: GENERALLY SW-SE 5-15 KT EACH
DAY, WITH GUSTS 25-35 KT ACROSS PORTIONS OF SE OREGON.
PREV DISCUSSION
SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...A COLD FRONT IS
BEGINNING TO TRACK INTO THE PACIFIC NORTHWEST, WITH
PRECIPITATION ON THE WAY FOR THE REGION BEGINNING LATE TOMORROW
MORNING. HIGH TO MID LEVEL CLOUDS ARE SPREAD ACROSS THE REGION,
WITH SUNSHINE PEAKING THROUGH AND ALLOWING FOR SOME HEATING
THIS AFTERNOON. A PUSH OF WARM AIR WITH INITIAL PRECIPITATION
TOMORROW MORNING IN EASTERN OREGON WILL LEAD TO A LOW CHANCE
(10-20% CHANCE) OF FREEZING RAIN BEFORE 11AM PST, MAINLY WEST OF
BURNS, OR AND NEAR HIGHWAY 20 AND 395. HIGH TEMPERATURES WILL
BE WARM TODAY THROUGH TOMORROW MORNING, LOWERING SLIGHTLY AFTER
THE FRONTAL PASSAGE TOMORROW AFTERNOON. BREEZY WINDS WILL
ACCOMPANY THE PASSAGE, SHIFTING FROM SOUTHEAST TO WESTERLY BY
THE LATE AFTERNOON. MINIMAL ACCUMULATIONS FROM VALLEY RAIN AND
MOUNTAIN SNOW WILL OCCUR, WITH THE BEST CHANCE OF PRECIPITATION
IN THE WEST CENTRAL MOUNTAINS-BAKER COUNTY REGION AND OVER THE
OWYHEE MOUNTAINS. PORTIONS OF THE SNAKE RIVER VALLEY IN THE LEE
OF THE OWYHEE MOUNTAINS WILL LIKELY BE SHADOWED BY THE
PRECIPITATION DUE TO THE ORIENTATION OF THE SHORTWAVE TROUGH.
THE MAGIC VALLEY-CAMAS PRAIRIE COULD SEE A FEW SPRINKLES, BUT
CONFIDENCE IS LOW IN ANY MEASURABLE PRECIPITATION BY SUNDAY
AFTERNOON FOR THAT AREA.
A BRIEF BREAK IN PRECIPITATION WILL OCCUR ON SUNDAY MORNING,
AHEAD OF ANOTHER INCOMING SYSTEM EARLY SUNDAY AFTERNOON.
WIDESPREAD PRECIPITATION IS LIKELY WITH THIS SYSTEM MOVING IN
FROM THE SOUTHWEST. SNOW LEVELS WILL REMAIN HIGH, AROUND
5500-6500 FEET WITH THIS PUSH. ACCUMULATIONS WILL CONTINUE
THROUGH MONDAY, WITH MINIMAL AMOUNTS FORECAST WITH THIS SYSTEM
AS WELL.
LONG TERM...MONDAY THROUGH FRIDAY...NO SIGNIFICANT CHANGE IN THE
ACTIVE WEATHER PATTERN IS EXPECTED IN THE EXTENDED PERIOD. MONDAY
APPEARS TO BE THE DRIEST DAY OF THE FORECAST AS THE REGION WILL BE
POSITIONED BETWEEN WEATHER SYSTEMS. HOWEVER, THE NEXT SERIES OF
TROUGHS COULD BRING SUBSTANTIAL PRECIPITATION. A PACIFIC TROUGH IS
ANTICIPATED TO MOVE INLAND ON TUESDAY, BRINGING A 70-90% CHANCE OF
RAIN AND SNOW, ALONG WITH MODERATE PRECIPITATION AMOUNTS. AHEAD OF
THIS SYSTEM, A SOUTHWEST FLOW ALOFT WILL USHER IN MILD AIR, RAISING
SNOW LEVELS TO 5000–7000 FEET. MOST PRECIPITATION IS EXPECTED
TO OCCUR ALONG THE COLD FRONT, WITH SNOW LEVELS DROPPING TO
3500–5500 FEET. RAIN IS LIKELY IN THE LOWER VALLEYS, WHILE
SEVERAL INCHES OF SNOW COULD ACCUMULATE IN THE MOUNTAINS. HIGH
TEMPERATURES ON MONDAY AND TUESDAY ARE EXPECTED TO AVERAGE ABOUT
10 DEGREES ABOVE NORMAL, WITH BREEZY WINDS DEVELOPING TUESDAY
AS THE FRONT PASSES THROUGH.
COOLER AND BREEZY CONDITIONS ARE FORECAST FOR CHRISTMAS DAY AS THE
TROUGH MOVES EASTWARD. THIS COOL-DOWN WILL BE BRIEF, AS ANOTHER DEEP
UPPER LOW FROM THE GULF OF ALASKA IS PREDICTED TO BRING ABUNDANT
MOISTURE AND A SERIES OF SHORTWAVE TROUGHS INTO THE PACIFIC
NORTHWEST THURSDAY AND FRIDAY, POTENTIALLY CONTINUING INTO THE
FOLLOWING WEEKEND. THIS SYSTEM COULD RESEMBLE AN ATMOSPHERIC RIVER
EVENT, WITH MODERATE TO HEAVY PRECIPITATION TOTALS EXPECTED.
PRECIPITATION PROBABILITIES WILL REMAIN ELEVATED AT 60-90% FROM
THURSDAY THROUGH FRIDAY, WHICH IS NOTABLY HIGH FOR THIS FAR IN
ADVANCE, INDICATING AN EXTENDED PERIOD OF WET WEATHER. THE SYSTEM
WILL BE COOLER THAN THE ONE EARLIER IN THE WEEK BUT NOT COLD ENOUGH
TO BRING VALLEY SNOW. SNOW LEVELS ARE PROJECTED TO RANGE BETWEEN
3000 AND 4500 FEET, FOR THE POTENTIAL OF HEAVY MOUNTAIN SNOW
LATE NEXT WEEK AND INTO THE WEEKEND. TEMPERATURES DURING THIS
TIME WILL AVERAGE ABOUT 5 DEGREES ABOVE NORMAL, WITH BREEZY
WINDS EXPECTED ON THURSDAY AND FRIDAY.
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.....KA
SHORT TERM...SA
LONG TERM....JDS
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