666
FXUS65 KPIH 071918
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
118 PM MDT WED OCT 7 2026
KEY MESSAGES
- QUIET & UNSEASONABLY WARM THROUGH FRIDAY: ABNORMALLY WARM
OCTOBER WEATHER CONTINUES WITH CLEAR SKIES, LIGHT WINDS, AND
ZERO PRECIPITATION CHANCES THROUGH THE END OF THE WORKWEEK.
- BREEZY SATURDAY SHIFT: WINDS WILL INCREASE ON SATURDAY AS A
REGIONAL PRESSURE GRADIENT TIGHTENS AHEAD OF AN APPROACHING
TROUGH, WITH RAIN CHANCES SPREADING SOUTHWEST TO NORTHEAST
DURING THE AFTERNOON AND EVENING.
- CUTOFF LOW & TROPICAL MOISTURE SURGE (SUNDAY–MONDAY): MODELS
ARE TRENDING TOWARD A CUTOFF LOW OVER CENTRAL CALIFORNIA AND
NEVADA TAPPING INTO TROPICAL MOISTURE FROM THE REMNANTS OF TC
RACHEL. THIS SETUP COULD BRING WIDESPREAD HEAVY RAIN OF 0.50"
TO 1.50" IN LOWER VALLEYS AND EASTERN HIGHLANDS, AND 0.25" TO
0.75" IN THE CENTRAL MOUNTAINS BUT SOME UNCERTAINTY REMAINS
- FALL COOLDOWN & MOUNTAIN SNOW: TEMPERATURES DROP WELL BELOW
NORMAL STARTING SUNDAY, MARKING A LIKELY END TO LATE-SUMMER-
LIKE WARMTH. WHILE LOWER-ELEVATION VALLEY SNOW LOOKS LESS
LIKELY, HIGHER-TERRAIN SNOWFALL REMAINS EXPECTED.
DISCUSSION
ISSUED AT 109 PM MDT WED OCT 7 2026
AFTERNOON SATELLITE IMAGERY SHOWS VIRTUALLY NO CLOUD COVER
ACROSS EASTERN IDAHO AS QUIET AND ABNORMALLY WARM OCTOBER
WEATHER CONTINUES. A STABLE SYNOPTIC REGIME WILL MAINTAIN THIS
PATTERN THROUGH THE END OF THE WORKWEEK, WITH ONLY SUBTLE DAY-
TO-DAY TEMPERATURE FLUCTUATIONS AND NO APPRECIABLE CHANCES FOR
PRECIPITATION. DAYTIME HIGHS WILL RUN WELL ABOVE SEASONAL
CLIMATOLOGICAL NORMS, ACCOMPANIED BY LIGHT WINDS AND CLEAR
OVERNIGHT SKIES.
WEATHER CONDITIONS BEGIN TO TRANSITION DRASTICALLY ON SATURDAY
AS A POTENT UPPER-LEVEL TROUGH APPROACHES THE INTERMOUNTAIN
WEST. SURFACE WINDS WILL PICK UP NOTICEABLY DURING THE DAY AS
THE REGIONAL PRESSURE GRADIENT TIGHTENS. INCREASED CLOUD COVER
AND WIND MIXING WILL INITIATE A COOLING TREND, THOUGH DAYTIME
MAXIMUM TEMPERATURES WILL STILL MANAGE TO HOLD A FEW DEGREES
ABOVE SEASONAL AVERAGES ACROSS MOST VALLEYS. CLOUD COVER AND
PRECIPITATION PROBABILITIES WILL INCREASE RAPIDLY DURING THE
SECOND HALF OF SATURDAY, SPREADING FROM SOUTHWEST TO NORTHEAST.
A MAJOR AIRMASS CHANGE OVERSPREADS EASTERN IDAHO FOR THE SECOND
HALF OF THE WEEKEND INTO EARLY NEXT WEEK, DROPPING TEMPERATURES
WELL BELOW SEASONAL NORMALS. OPERATIONAL MODELS HAVE TRENDED
TOWARD CONSOLIDATING A CUTOFF LOW OVER CENTRAL CALIFORNIA AND
NEVADA SUNDAY INTO MONDAY, THOUGH ENSEMBLE GUIDANCE MAINTAINS
MINOR VARIANCE REGARDING THE FINAL TRACK.
ASSUMING THIS CUTOFF SOLUTION MATERIALIZES, A MOIST SOUTHERLY-
TO-SOUTHWESTERLY FLOW WILL BECOME LOCKED OVER EASTERN IDAHO,
MAINTAINING PERSISTENT PRECIPITATION THROUGH EARLY NEXT WEEK.
ADDING TO THE PRECIPITATION POTENTIAL WILL BE AN INFLUX OF
TROPICAL MOISTURE FROM THE REMNANTS OF TROPICAL CYCLONE RACHEL.
THIS RICH MOISTURE TAP SUPPORTS WIDESPREAD HEAVY PRECIPITATION
ACROSS MUCH OF EASTERN IDAHO, WITH CURRENT QPF FORECASTS CALLING
FOR 0.50 TO 1.50 INCHES ACROSS LOWER-ELEVATION VALLEYS AND THE
EASTERN HIGHLANDS, AND 0.25 TO 0.75 INCHES ACROSS THE CENTRAL
MOUNTAINS. WHILE SOME UNCERTAINTY REMAINS REGARDING THE EXACT
TRACK AND TIMING OF THE CUTOFF LOW AND THUS PRECIP AMOUNTS -
CONFIDENCE IS VERY HIGH IN A PROLONGED TRANSITION TO A COOL, WET
AUTUMN PATTERN — LIKELY SIGNALING AN END TO OUR LATE-SUMMER-
LIKE WEATHER FOR THE SEASON. BELOW-NORMAL TEMPERATURES AND
PERIODIC RAIN AND MOUNTAIN SNOW SHOWERS WILL PERSIST WELL INTO
NEXT WEEK. LOWER-ELEVATION VALLEY SNOW LOOKS LESS LIKELY WITH
THIS ITERATION OF THE FORECAST, BUT HIGHER-TERRAIN SNOWFALL
REMAINS EXPECTED. FORECAST UPDATES WILL CONTINUE TO REFINE SNOW
LEVELS AND QPF TOTALS AS GUIDANCE CONVERGES OVER THE COMING
DAYS.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 1118 AM MDT WED OCT 7 2026
LIGHT WINDS AND VFR SKIES CONTINUE INTO THURSDAY.
FIRE WEATHER
ISSUED AT 109 PM MDT WED OCT 7 2026
DRY CONDITIONS WITH ABOVE NORMAL TEMPERATURES CONTINUE INTO
FRIDAY. OVERNIGHT HUMIDITY RECOVERY MAY BE POOR ESPECIALLY AT
HIGHER ELEVATIONS. WINDS BEGIN TO INCREASE LATE FRIDAY IN
RESPONSE TO BREAKDOWN OF THE UPPER RIDGE AS THE NEXT SYSTEM
APPROACHES EAST IDAHO. HIGHER ELEVATIONS MAY APPROACH CRITICAL
CONDITIONS WITH VERY DRY HUMIDITIES AND GUSTY WINDS. RIGHT NOW
THE CONDITIONS LOOK MARGINAL, SO NO HEADLINES ARE ANTICIPATED.
TEMPERATURES BEGIN TO SLIDE SATURDAY AS CLOUD COVER AND
PRECIPITATION INCREASE THROUGH THE DAY. WINDS REMAIN BREEZY, BUT
HUMIDITIES INCREASE, LIMITING CRITICAL CONDITIONS. MUCH COOLER
TEMPERATURES ARRIVE BY SUNDAY WITH WIDESPREAD PRECIPITATION.
SNOW WILL BE POSSIBLE ABOVE 8000 FT ACROSS THE CENTRAL MOUNTAINS
AND ALONG THE DIVIDE. COOL TEMPERATURES AND UNSETTLED CONDITIONS
CONTINUE INTO MID WEEK NEXT WEEK.
PIH WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...MCKAUGHAN
AVIATION...DMH
FIRE WEATHER...DMH
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