134
FXUS65 KBOI 021601
AFDBOI
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BOISE ID
1001 AM MDT THU OCT 2 2025
DISCUSSION
RAIN SHOWERS AND INCREASING CLOUD COVER ARE
OCCURRING ACROSS PORTIONS OF SOUTH CENTRAL IDAHO THIS MORNING,
WITH MODELS ON TRACK TO BRING MORE INTO OUR REGION THIS
AFTERNOON. COOLER TEMPERATURES WITH BREEZY WINDS WILL ACCOMPANY
THE BAND OF PRECIPITATION, WITH THE HEAVIEST PRECIPITATION FROM
0.5-1.5 INCHES STILL LIKELY FROM WARM LAKE DOWN THROUGH IDAHO
CITY, BOISE, AND THE OWYHEE MOUNTAINS. ISOLATED THUNDERSTORMS
ARE POSSIBLE WITH THIS FRONTAL PASSAGE THIS AFTERNOON THROUGH
THE OVERNIGHT HOURS, WITH THE BEST CHANCE OVER THE NEVADA BORDER
AND SOUTHERN BOISE MOUNTAINS. THE FLASH FLOOD WATCH IS STILL IN
EFFECT, WITH BURN SCARS AND STEEP AND ROCKY DRAINAGES THE
HIGHEST RISK. NO UPDATES TO THE FORECAST.
AVIATION
FOG AND LOW STRATUS THIS MORNING NEAR KMYL
RESULTING IN LIFR, CONDITIONS IMPROVING BY 18Z. ISOLATED SHOWERS
ACROSS SW-IDAHO THIS MORNING. PRECIPITATION BECOMING MORE WIDESPREAD
WITH EMBEDDED THUNDERSTORMS LATE THURSDAY AFTERNOON ACROSS E-OREGON
AND SW-IDAHO. MVFR/IFR AND LOCALIZED LIFR IN HEAVIER PRECIP AND LOW
CLOUDS, MOUNTAINS OBSCURED IN PRECIP. SURFACE WINDS: VARIABLE UP TO
10KT, WITH W-NW GUSTS OF 20KT THIS AFTERNOON EAST OF KBOI. WINDS
ALOFT AT 10KFT MSL: SW 15-30 KT.
KBOI...VFR THIS MORNING. RAIN SHOWERS AFTER THU/23Z, CONTINUING
THROUGHOUT THE NIGHT. PERIODS OF MVFR/IFR IN HEAVIER PRECIP THURSDAY
NIGHT. SURFACE WINDS: VARIABLE 4-8KT THIS MORNING, BRIEFLY BECOMING
NW 8-12KT WITH GUSTS TO 20 KT AFTER FRI/00Z.
WEEKEND OUTLOOK: SHOWERS CONTINUING IN SW-IDAHO THROUGH SATURDAY
MORNING. BEFORE ISOLATED SHOWERS ACROSS THE CENTRAL IDAHO MOUNTAINS
SATURDAY AND SUNDAY AFTERNOONS. SNOW LEVELS LOWERING TO 6-7KFT BY
SUNDAY AFTERNOON. SURFACE WINDS: N-NW 10-15 KT GUSTING TO 20-30 KT
SATURDAY WITH LOCALIZED GUSTS TO 40 KT IN THE SNAKE PLANE.
BECOMING N-NW 5-15 KT BY SUNDAY AFTERNOON.
PREV DISCUSSION
SHORT TERM...TODAY THROUGH SATURDAY NIGHT...OVERNIGHT WATER
VAPOR SATELLITE IMAGERY SHOWING AN ELONGATING TROUGH ALONG THE
WEST COAST, DEFINED BY A CLOSED LOW OFF THE BC COAST AND
SECONDARY WAVE DIGGING TOWARD THE CENTRAL CA COAST. WE'LL REMAIN
POSITIONED ALONG THE EASTERN EDGE OF THE TROUGH WITH A WEAK
FRONTAL BOUNDARY AS THE FOCUS OF SHOWER DEVELOPMENT TODAY.
LINING UP OVER S-CENTRAL IDAHO THIS MORNING, THE FRONT WILL
SHIFT WESTWARD THROUGH THE DAY. BY THIS EVENING IT WILL ROUGHLY
EXTEND FROM SOUTHERN MALHEUR COUNTY THROUGH THE TREASURE VALLEY
INTO THE BOISE AND W-CENTRAL IDAHO MTNS. THE FRONT WILL BRIEFLY
STALL IN THIS POSITION TONIGHT INTO FRIDAY ALLOWING FOR A NARROW
BAND OF MODERATE TO LOCALLY HEAVY RAIN TO FORM. MOUNTAIN SITES
IN THE OWHYEE'S UP THROUGH IDAHO CITY, LOWMAN, WARM LAKE AND
YELLOW PINE ARE INLINE FOR 0.75-1.25 INCHES OF RAIN THROUGH
MIDDAY FRIDAY. BANNER SUMMIT AND THE WAPITI BURN SCAR ARE NOW ON
THE EASTERN FRINGE OF THE FORECAST HEAVIER RAINFALL WITH
0.75-1" EXPECTED. IN THE SNAKE PLAIN THE RAINFALL MAXIMUM COVERS
CALDWELL TO MTN HOME WITH RAIN TOTALS OF 0.4-0.6". THE FLASH
FLOOD WATCH WILL REMAIN IN PLACE WITH THE CONCERN BEING AREAS
IN AND AROUND BURN SCARS.
THE TROUGH/FRONT WILL SLOWLY SHIFT EASTWARD THROUGH SATURDAY.
THIS WILL KEEP A 60+% CHANCE OF RAIN ACROSS SOUTHERN HARNEY AND
MALHUER COUNTIES AND HIGHER TERRAIN OF SW IDAHO THROUGH FRIDAY
NIGHT. IT WILL ALSO ACT TO FILL IN PRECIPITATION OVER THE
WESTERN MAGIC VALLEY WHICH IS GOING TO MISS OUT ON MOST OF
TONIGHT'S RAINFALL. A 20-25% CHANCE OF SHOWERS LINGER IN THE SW
IDAHO MTNS AND CENTRAL SNAKE PLAIN ON SATURDAY, DROPPING TO
LESS THAN 20% SATURDAY NIGHT. SNOW LEVELS WILL DROP TO AROUND
7KFT MSL SATURDAY NIGHT SO ANY LINGERING SHOWERS COULD BRING
LIGHT SNOW TO THE MTN TOPS. GUSTY WINDS WILL FOLLOW THE FRONT
FRIDAY NIGHT INTO SATURDAY. IN TYPICAL FASHION THE STRONGEST
WINDS WILL BLOW THROUGH THE SNAKE PLAIN EAST OF BOISE WHERE 30
MPH WINDS AND GUSTS TO 45 MPH ARE POSSIBLE. TODAY WILL BRING
LITTLE CHANGE IN TEMPERATURES FROM YESTERDAY, WITH 5-15 DEGREES
OF COOLING BEHIND THE FRONT ON FRIDAY.
LONG TERM...SUNDAY THROUGH THURSDAY...A SHORTWAVE TROUGH
AMPLIFIES SUNDAY EVENING, EXTENDING FROM MONTANA TO NORTHERN
CALIFORNIA. THE AMPLIFICATION WILL BRING A SLIGHT CHANCE OF
SHOWERS AND STORMS TO CENTRAL IDAHO SUNDAY, WITH A WINTRY MIX
POSSIBLE FOR MOUNTAINS WITH SNOW LEVELS AROUND 7 KFT MSL. AS THE
NOW LONGWAVE TROUGH BECOMES CLOSED OVER NORTHERN CALIFORNIA,
AND A CLOSED HIGH DEVELOPS OFF THE CANADIAN WEST COAST,
DETERMINISTIC MODEL AGREEMENT LESSENS MONDAY THROUGH THURSDAY.
THIS BLOCKED PATTERN WILL AT LEAST KEEP US DRY THROUGH THE EARLY
PARTS OF NEXT WEEK. WHETHER IT'S AN OMEGA OR REX BLOCK... I'LL
CONCEDE TO THE REX BLOCK DESIGNATION THAT DAY SHIFT PRESCRIBED,
BUT ONLY DUE TO THE BRIEF NATURE OF THE BLOCK. AN OMEGA WOULD
NORMALLY BE FAIRLY PERSISTENT, BUT A STRENGTHENING ALASKAN LOW
WILL MOVE SOUTHEASTWARD INTO THE CLOSED HIGH, DISRUPTING THE
BALANCE OF THE BLOCK. MOST ENSEMBLE MEMBERS SHOW THE DISRUPTION,
BUT A HEALTHY CHUNK OF OTHERS, INCLUDING THE GFS DETERMINISTIC,
SHOW THE ALASKAN LOW MOVING SOUTH INTO THE PACIFIC BEFORE
HEADING EASTWARD AND ONTO THE COAST. THESE TWO DIFFERING
SOLUTIONS LEAD TO WIDELY DIFFERENT SCENARIOS WEDNESDAY ONWARD.
BOTH HINT AT UNSETTLED PATTERNS, BUT THE COASTAL TRACK IS FAR
MORE DYNAMIC THAN THE PACIFIC SOUTHWARD TRACK.
BOI WATCHES/WARNINGS/ADVISORIES
ID...FLASH FLOOD WATCH FROM 6 PM MDT THIS EVENING THROUGH FRIDAY
AFTERNOON IDZ011-013.
OR...NONE.
WWW.WEATHER.GOV/BOISE
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSBOISE
WWW.X.COM/NWSBOISE
DISCUSSION...SA
AVIATION.....NF
SHORT TERM...DG
LONG TERM....JM
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