889
FXUS65 KPIH 092010
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
210 PM MDT FRI OCT 9 2026
KEY MESSAGES
- FLOOD WATCH IN EFFECT (SATURDAY–MONDAY): A FLOOD WATCH COVERS
MOST OF EASTERN IDAHO—INCLUDING SUN VALLEY EAST THROUGH THE
MAGIC VALLEY, SNAKE PLAIN, AND EASTERN/SOUTHEASTERN
HIGHLANDS—FOR A MULTI-DAY RAINFALL EVENT OF 1.0 TO 2.0 INCHES,
WITH LOCALIZED TOTALS UP TO 3.0 INCHES POSSIBLE NEAR ISLAND
PARK AND INTO THE EASTERN HIGHLANDS. NBM GUIDANCE SHOWS AN 80%
TO 100% PROBABILITY OF EXCEEDING 1.0 INCH OF RAINFALL
ALONG/EAST OF THE I-15 CORRIDOR AND THE SOUTH HILLS, WITH A
30% TO 80% PROBABILITY OF EXCEEDING 2.0 INCHES.
- DRAMATIC WEEKEND COOLDOWN: TODAY'S UPPER 70S AND 80S MARK THE
FINAL WARM DAY OF THE SEASON. HIGHS DROP BELOW 70 ON SATURDAY
AND PLUMMET INTO THE 40S AND 50S ON SUNDAY.
- FROST/FREEZE HEADLINES AHEAD: WIDESPREAD COOL TEMPERATURES
WILL BRING FROST/FREEZE RISKS STARTING SUNDAY MORNING,
BECOMING MORE LIKELY MONDAY THROUGH MID-WEEK BEFORE HEADLINES
ARE SUSPENDED FOR THE SEASON.
DISCUSSION
ISSUED AT 206 PM MDT FRI OCT 9 2026
A MAJOR PATTERN SHIFT GETS UNDERWAY ACROSS THE INTERMOUNTAIN
WEST TODAY. SATELLITE IMAGERY SHOWS INCREASING CLOUDINESS OVER
EASTERN WASHINGTON AND OREGON ASSOCIATED WITH AN APPROACHING
UPPER-LEVEL TROUGH. TEMPERATURES TODAY HAVE CLIMBED QUICKLY INTO
THE 70S AND 80S, MARKING THE FINAL DAY OF 80-DEGREE WARMTH FOR
THE FORESEEABLE FUTURE. SATURDAY REPRESENTS THE LEADING EDGE OF
THE COOLER, WETTER AIR MASS, WITH LOWER-ELEVATION MAXIMUM
TEMPERATURES STRUGGLING TO REACH 70 DEGREES. SHOWERS AND
EMBEDDED THUNDERSTORMS WILL DEVELOP DURING THE DAY ON SATURDAY,
ELEVATING LOCALIZED RAINFALL RATES AND INITIATING A MULTI-DAY
PRECIPITATION EVENT.
SUNDAY WILL BE THE WETTEST AND MOST IMPACTFUL DAY OF THE
FORECAST PERIOD AS THE UPPER-LEVEL LOW TRACKS SLOWLY ACROSS THE
GREAT BASIN. A FLOOD WATCH HAS BEEN ISSUED FOR MOST OF EASTERN
IDAHO, EXTENDING FROM SUN VALLEY EASTWARD ACROSS THE MAGIC
VALLEY, SNAKE PLAIN, AND THE EASTERN AND SOUTHEASTERN HIGHLANDS.
WIDESPREAD RAINFALL TOTALS OF 1.0 TO 2.0 INCHES ARE VERY LIKELY
BETWEEN SATURDAY AND MONDAY. NATIONAL BLEND OF MODELS (NBM)
PROBABILITIES FOR STORM TOTALS EXCEEDING 1.0 INCH REACH 80% TO
100% ALONG AND EAST OF THE I-15 CORRIDOR AND INTO THE SOUTH
HILLS, WITH 2.0-INCH PROBABILITIES RANGING FROM 30% TO 80%. THE
HIGHEST QPF FOOTPRINT IS FOCUSED ACROSS THE EASTERN HIGHLANDS
AND TOWARD ISLAND PARK, WHERE LOCALIZED 3.0-INCH TOTALS ARE
POSSIBLE. WHILE PERSISTENT LIGHT-TO-MODERATE RAIN IS THE PRIMARY
DRIVER, EMBEDDED SATURDAY/SUNDAY CONVECTION COULD BOOST
LOCALIZED TOTALS AND CREATE LOCALIZED FLOODING CONCERNS. STRONG
COLD ADVECTION ON SUNDAY WILL HOLD DAYTIME HIGHS IN THE 40S AND
50S.
AS THE PRIMARY UPPER LOW SLOWLY CROSSES THE INTERMOUNTAIN WEST,
PRECIPITATION CHANCES WILL LINGER THROUGH MONDAY AND TUESDAY.
RAINFALL INTENSITY WILL WANE COMPARED TO SUNDAY, WITH CONDITIONS
GRADUALLY DRYING OUT BY MID-WEEK. UNSEASONABLY COOL AIR WILL
REMAIN LOCKED OVER THE REGION, HOLDING DAYTIME HIGHS IN THE 50S
THROUGH MUCH OF NEXT WEEK, WITH A SLIGHT RECOVERY TOWARD THE
LOWER 60S POSSIBLE BY LATE WEEK. WITH COLD AIR ESTABLISHED
BEHIND THE DEPARTING SYSTEM, ATTENTION SHIFTS TO OVERNIGHT
FREEZE RISKS. FROST AND FREEZE HEADLINES MAY BE NEEDED AS EARLY
AS SUNDAY MORNING, WITH A MUCH HIGHER LIKELIHOOD MONDAY MORNING
THROUGH MID-WEEK AS SKIES CLEAR DURING OVERNIGHT HOURS. THESE
CHILLY NIGHTS WILL LIKELY RESULT IN THE SEASONAL SUSPENSION OF
FROST/FREEZE HEADLINES FOR EASTERN IDAHO AT SOME POINT MID-WEEK.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1158 AM MDT FRI OCT 9 2026
AFTER A LONG PERIOD OF LIGHT WINDS AND CLEAR SKIES, CONDITIONS
BEGIN TO TURN STARTING THIS AFTERNOON. WINDS INCREASE ACROSS THE
REGION, PEAKING AROUND 15KTS SUSTAINED WITH GUSTS AROUND 25KTS.
THEY DECREASE SLIGHTLY OVERNIGHT, BUT PICK UP AGAIN SATURDAY
MORNING. SUN SHOULD EXPERIENCE NORMAL DIURNAL DOWN-VALLEY WINDS
THIS EVENING, BUT THE INCOMING UPPER LOW IS EXPECTED TO TURN SUN
WINDS SOUTHERLY OR SOUTHWESTERLY AROUND SUNRISE. CLOUD COVER
INCREASES INTO TONIGHT AS MOISTURE DEEPENS ACROSS EAST IDAHO,
BUT VFR IS STILL EXPECTED. PIH, IDA AND DIJ COULD SEE A FEW SHRA
BY SUNRISE, BUT DIJ HAS THE BETTER CHANCES OF PRECIPITATION
AFTER SUNRISE AND WILL CARRY PROB30.
FIRE WEATHER
ISSUED AT 206 PM MDT FRI OCT 9 2026
FALL ARRIVES THIS WEEKEND ACROSS EAST IDAHO. WINDS REMAIN GUSTY
THIS AFTERNOON, WITH CRITICAL OR NEAR CRITICAL CONDITIONS
ESPECIALLY ACROSS THE SOUTHWEST AMID VERY DRY HUMIDITIES.A RED
FLAG WARNING REMAINS IN EFFECT UNTIL 8 PM FOR ZONE 427. WINDS
REMAIN BREEZY OVERNIGHT, BUT HUMIDITIES RISE AFTER SUNSET.
MOISTURE CONTINUES TO INCREASE OVERNIGHT AS REMNANTS OF TROPICAL
SYSTEM RACHEL BEGIN TO PUSH THROUGH THE GREAT BASIN AHEAD OF
UPPER LOW DROPPING THROUGH THE PACIFIC NORTHWEST. THE
COMBINATION OF THESE FEATURES WILL RESULT IN A RAPID CHANGE IN
THE PATTERN THROUGH THE WEEKEND, WITH ONSET OF ISOLATED TO
WIDELY SCATTERED SHOWERS ARRIVING AS EARLY AS TONIGHT ACROSS THE
CENTRAL MOUNTAINS, SPREADING ACROSS THE REMAINDER OF EAST IDAHO
THROUGH THE DAY SATURDAY. RAINFALL CONTINUES INTO EARLY NEXT
WEEK, BUT SUNDAY LOOKS TO BE THE HEAVIEST DAY FOR MOST AREAS.
OVERALL TOTALS SATURDAY THROUGH MONDAY ARE FORECAST TO RANGE
0.35-0.50" FOR ZONES 475 AND 476, 0.50-1.50" FOR MUCH OF THE
SNAKE PLAIN. MORE WIDESPREAD TOTALS FOR THE 3 DAY PERIOD ARE
ACROSS THE SOUTHERN AND EASTERN HIGHLANDS, ZONES 427, 413, AND
411, WHERE SOME LOCATIONS WILL EXCEED 2" OF LIQUID
PRECIPITATION. A FLOOD WATCH IS NOW IN EFFECT SATURDAY AFTERNOON
THROUGH MONDAY FOR REGIONS EXPECTED TO SEE THE HIGHEST RAINFALL
TOTALS. MUCH COOLER TEMPERATURES DROP INTO EAST IDAHO ALONG WITH
THE RAINFALL, WHICH MEANS ACCUMULATION OF SNOW AT HIGHER
ELEVATIONS, BRIEFLY DIPPING TO MID-SLOPES ESPECIALLY ACROSS THE
CENTRAL MOUNTAINS DURING OVERNIGHT HOURS. THE GREATEST AFFECTS
WILL BE ABOVE 7500-8000 FT ELEVATIONS.
PIH WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH MONDAY AFTERNOON
FOR IDZ051>067-073-075.
RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR IDZ427.
DISCUSSION...MCKAUGHAN
AVIATION...DMH
FIRE WEATHER...DMH
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