361
FXUS65 KBOI 220521
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1121 PM MDT SAT MAR 21 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- A COLD FRONTAL PASSAGE SATURDAY WILL BRING COOLER
TEMPERATURES, LIGHT MOUNTAIN SHOWERS, AND GUSTY W-NW WINDS
THROUGH THE EVENING.
- WARM, SLIGHTLY ABOVE NORMAL TEMPERATURES WILL CONTINUE THE
MIDDLE OF NEXT WEEK.
- ANOTHER COLD FRONT WILL MOVE THROUGH THE REGION BY THE MIDDLE
OF NEXT WEEK, BRINGING MOUNTAIN SHOWERS AND COOLER
TEMPERATURES.
SHORT TERM /THROUGH MONDAY NIGHT/
ISSUED 224 PM MDT SAT MAR 21 2026
A WEAK COLD FRONT IS CONTINUING TO PUSH SOUTHEASTWARD ACROSS
THE FORECAST AREA THIS EVENING. WHILE THE FRONT IS NOT WELL
DEFINED IN SURFACE OBSERVATIONS, IT IS CLEARLY DEMARCATED BY A
DEVELOPING CUMULUS FIELD ON SATELLITE IMAGERY. THE PRIMARY
IMPACT HAS BEEN ELEVATED WINDS THIS AFTERNOON AND EVENING, WITH
WIND GUSTS REACHING UP TO 40 MPH IN WIND-PRONE AREAS.
PRECIPITATION CHANCES REMAIN LOW AS THE DEEPEST MOISTURE STAYS
TO OUR NORTH, THOUGH A 10 TO 20 PERCENT CHANCE OF LIGHT RAIN
SHOWERS WILL CONTINUE FOR NORTHERN PORTIONS OF BAKER AND VALLEY
COUNTIES THROUGH TONIGHT.
THE RIDGE BEGINS TO BUILD BACK OVER THE AREA ON SUNDAY. THIS
WILL SHIFT THE COOLER ZONAL FLOW FURTHER NORTH, KEEPING OUR
REGION DRY. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE
PERIOD. BY MONDAY NIGHT, AN ATMOSPHERIC RIVER ASSOCIATED WITH A
LOW OFF THE BRITISH COLUMBIA COAST WILL BEGIN TO APPROACH THE
PACIFIC NORTHWEST. WHILE THIS SYSTEM WILL ATTEMPT TO PUSH
MOISTURE AND COLDER AIR INTO THE REGION, IT WILL FACE RESISTANCE
FROM THE PERSISTENT RIDGE OVER THE DESERT SOUTHWEST. GUIDANCE
TODAY CONTINUES TO TREND WARMER AND DRIER; CONSEQUENTLY, ANY
PRECIPITATION THROUGH MONDAY NIGHT IS EXPECTED TO REMAIN LIGHT
AND CONFINED MOSTLY TO THE HIGHER TERRAIN OF BAKER COUNTY AND
THE MOUNTAINS OF SOUTHWEST IDAHO.
LONG TERM /TUESDAY THROUGH SATURDAY/
ISSUED 224 PM MDT SAT MAR 21 2026
THE LARGE UPPER LEVEL RIDGE OVER WESTERN US THE WILL FLATTEN
OUT A BIT ALLOWING A MORE ZONAL WEST TO EAST UPPER LEVEL FLOW TO
BRING MOISTURE INTO THE AREA ON TUESDAY AND WEDNESDAY. THE BEST
CHANCES FOR PRECIPITATION WILL BE ACROSS THE NORTHERN HALF OF
OUR FORECAST AREA WHERE A 50 TO 60 PERCENT CHANCE OF RAIN
EXISTS. THE SOUTHERN HALF OF THE FORECAST AREA WILL REMAIN DRY.
THE ZONAL FLOW PATTERN SHOULD ALLOW TEMPERATURES TO COOL DOWN A
BIT WEDNESDAY THROUGH THURSDAY, THOUGH STILL REMAINING ABOVE 5
TO 10 DEGREES ABOVE NORMAL. MOST MODELS SHOW THE RIDGE BEGINNING
TO REBUILD OVER THE WESTERN US AGAIN BY FRIDAY AND CONTINUE
THAT PATTERN INTO THE WEEKEND. THE FORECAST FOR SOUTHWESTERN
IDAHO AND SOUTHEASTERN OREGON RESPONDS TO THAT SCENARIO AND
SHOWS A WARMING TREND STARTING ON FRIDAY WITH DRY WEATHER.
AVIATION /06Z SUNDAY THROUGH MONDAY/
ISSUED 1120 PM MDT SAT MAR 21 2026
VFR CONDITIONS WITH SCATTERED HIGH CLOUD COVERAGE OVERNIGHT.
WINDS WILL BE NW 10 KT OR LESS OVERNIGHT THROUGH SUNDAY MORNING,
EXCEPT 10-15 KT WITH GUSTS TO 25 KT OVER KMUO, KTWF, AND KJER.
WINDS ALOFT AT 10K FEET: W 30-40 KT.
KBOI...VFR. SURFACE WINDS W-NW 10 KT OR LESS OVERNIGHT THROUGH
THE AFTERNOON.
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
AVIATION.....JY
SHORT TERM...JDS
LONG TERM....JB
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