940
FXUS65 KBOI 120559
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1159 PM MDT SAT APR 11 2026
UPDATE
UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- ISOLATED AFTERNOON THUNDERSTORMS TODAY AND TOMORROW WITH
SMALL HAIL, GUSTY OUTFLOW WINDS, AND BRIEF HEAVY RAIN.
- SLIGHTLY BELOW NORMAL TEMPERATURES WITH VALLEY RAIN SHOWERS
AND MOUNTAIN SNOW SHOWERS SUNDAY AND MONDAY.
- MUCH COOLER TEMPERATURES WITH PERIODS OF PRECIPITATION
WEDNESDAY THROUGH FRIDAY.
SHORT TERM /THROUGH MONDAY NIGHT/
ISSUED 204 PM MDT SAT APR 11 2026
AN ACTIVE WEATHER PATTERN REMAINS IN PLACE AS AN UPPER LEVEL
LOW CONTINUES TO TRACK THROUGH THE GREAT BASIN AND INTERMOUNTAIN
WEST SUNDAY AND MONDAY. HOWEVER, THIS AFTERNOON AND EVENING,
THE LOW REMAINS OFF THE CALIFORNIA COAST WHICH IS ADVECTING WARM
MOIST AIR COMBINED WITH WEAK SURFACE INSTABILITY FOR
THUNDERSTORM DEVELOPMENT. THE MOST ROBUST ACTIVITY WILL OCCUR
THIS AFTERNOON THROUGH EARLY EVENING DURING PEAK HEATING. MAIN
THREATS WITH THESE STORMS INCLUDE GUSTY OUTFLOW WINDS UP TO 45
MPH, SMALL HAIL, AND BRIEF PERIODS OF HEAVY RAIN THAT COULD
REDUCE VISIBILITY. HAVE SEEN STORMS PRODUCE UP TO 0.30 TO 0.40
INCHES OF RAIN IN 30 MINUTES.
ON SUNDAY, THE CENTER OF THE LOW PRESSURE SYSTEM MOVES DIRECTLY
OVERHEAD. THIS WILL RESULT IN WIDESPREAD RAIN SHOWERS AND
MOUNTAIN SNOW SHOWERS. THE HEAVIEST PRECIPITATION WILL OCCUR
THROUGH SUNDAY MORNING ACROSS THE AREA AS THE LOW MOVES IN.
WHILE INSTABILITY WILL BE SLIGHTLY LOWER THAN TODAY DUE TO
COOLER SURFACE TEMPERATURES, THERE IS STILL ENOUGH ENERGY FOR
ISOLATED THUNDERSTORMS DURING THE AFTERNOON AND EVENING HOURS.
ANY STORMS THAT DEVELOP ON SUNDAY WILL LIKELY BE LESS INTENSE
THAN TODAY BUT STILL CAPABLE OF PRODUCING ERRATIC WINDS AND
SMALL HAIL. SNOW LEVELS WILL BEGIN TO LOWER, REACHING 5500 TO
7000 FEET MSL BY SUNDAY EVENING, WHICH MAY LEAD TO LIGHT SNOW
ACCUMULATIONS ON THE HIGHER PEAKS.
BY MONDAY AND MONDAY NIGHT, THE LOW BEGINS TO SHIFT SLOWLY
TOWARD THE ROCKIES. HIGH PRECIPITATION CHANCES (50 TO 90
PERCENT) REMAIN FOR MUCH OF THE AREA THROUGH MONDAY AS WRAP
AROUND MOISTURE CONTINUES. HOWEVER, THE COOLER AIR MASS WILL
SIGNIFICANTLY LIMIT INSTABILITY, MAKING THUNDERSTORM CHANCES
MUCH MORE ISOLATED COMPARED TO THE WEEKEND. SNOW LEVELS WILL
CONTINUE THEIR DOWNWARD TREND, POTENTIALLY DROPPING TO 4000 TO
5000 FEET BY MONDAY NIGHT. BREEZY CONDITIONS ARE EXPECTED TO
DEVELOP AS THE SYSTEM EXITS, WITH TEMPERATURES REMAINING WELL
BELOW SEASONAL NORMALS.
LONG TERM /TUESDAY THROUGH SATURDAY/
ISSUED 204 PM MDT SAT APR 11 2026
BRIEF RIDGING TUESDAY MORNING IS QUICKLY OVERCOME BY A STRONG
ALASKAN LOW. WINDS PICK UP TUESDAY EVENING AS CLOUD COVER
INCREASES. PRECIPITATION BEGINS WEDNESDAY MORNING AND LASTS
THROUGH THURSDAY. THE BULK OF THE PRECIPITATION FALLS WEDNESDAY
AFTERNOON, WITH AN AREA WIDE 80-90% CHANCE OF PRECIPITATION.
FORECAST RAINFALL AMOUNTS RANGE FROM 0.2- 0.4 INCHES IN VALLEYS,
AND 0.5-1 INCHES IN MOUNTAINS. NOT ALL THE PRECIP WILL FALL AS
RAIN. THE 540'S DM HEIGHTS IN THE LOW BRING SNOW LEVELS FROM 5-6
KFT MSL WEDNESDAY TO VALLEY FLOORS BY THURSDAY MORNING.
MOUNTAINS WILL RECEIVE 4-12 INCHES OF SNOW BEFORE THURSDAY.
THURSDAY, MOUNTAINS AND MOUNTAIN VALLEYS RECEIVE 1-4 INCHES OF
SNOW, WITH HIGHLANDS AND LOW ELEVATION VALLEYS RECEIVING A
DUSTING UP TO AN INCH. BREEZY 20-30 MPH GUSTS PERSIST THROUGH
WEDNESDAY AND THURSDAY. AS THE SYSTEM MOVES EASTWARD, SLIGHT
RIDGING MOVES IN FRIDAY AND SATURDAY LEADING INTO A WARMING AND
DRYING TREND. TEMPERATURES RISE FROM 15 DEGREES BELOW NORMAL UP
TO NEAR NORMAL ON SATURDAY.
AVIATION /06Z SUNDAY THROUGH MONDAY/
ISSUED 1158 PM MDT SAT APR 11 2026
NUMEROUS SHOWERS CONTINUING THROUGH SUNDAY NIGHT. LOW VFR-IFR IN
RAIN, AND IFR-LIFR IN MTN SNOW. MOUNTAINS BECOMING OBSCURED. SNOW
LEVELS LOWERING TO 5500-6500 FT MSL BY LATE MORNING. ISOLATED
THUNDERSTORMS IN THE AFTERNOON MAINLY IN SW IDAHO, CAPABLE OF GUSTS
TO 25-40 KT AND GRAUPEL/SMALL HAIL. SURFACE WINDS: VARIABLE 5-15 KT,
THEN S-W 10-20 KT WITH GUSTS TO 20-35 KT IN THE AFTERNOON. WINDS
ALOFT AT 10KFT MSL: SW 10-25 KT.
KBOI...GENERALLY VFR. RAIN SHOWERS RETURNING SUN/09Z-10Z, CONTINUING
THROUGH SUNDAY NIGHT. RAIN WILL BE MODERATE/HEAVY AT TIMES, CREATING
MVFR CONDITIONS. A SLIGHT CHANCE OF THUNDERSTORMS (20%) DURING THE
EARLY AFTERNOON, CAPABLE OF GUSTS TO 25-40 KT AND GRAUPEL/SMALL
HAIL. SURFACE WINDS OUTSIDE OF SHOWERS: E-S 5-15 KT.
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.....SH
SHORT TERM...JDS
LONG TERM....JM
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