591
FXUS65 KPIH 280425
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
1025 PM MDT SUN SEP 27 2026
KEY MESSAGES
- NIGHTTIME SHOWERS EAST OF I-15: AN APPROACHING UPPER-LEVEL
TROUGH WILL INCREASE CLOUDS TONIGHT, BRINGING A BRIEF ROUND OF
SHOWERS AND ISOLATED THUNDERSTORMS PRIMARILY ALONG AND EAST
OF THE I-15 CORRIDOR, FOCUSING OVER THE EASTERN HIGHLANDS.
- NOTICEABLY COOLER MONDAY: SHOWERS EXIT RAPIDLY MONDAY WITH
CLEARING SKIES. POST-FRONTAL AIR WILL DROP VALLEY DAYTIME
HIGHS INTO THE 60S—ROUGHLY 10 DEGREES COOLER THAN TODAY'S
READINGS.
- EARLY OCTOBER WARMING TREND: HIGH PRESSURE BUILDS OVER THE
INTERMOUNTAIN WEST STARTING WEDNESDAY, KEEPING THE REMAINDER
OF THE 7-DAY FORECAST COMPLETELY DRY WHILE PUSHING LOWER-
ELEVATION HIGHS INTO THE MID-TO-UPPER 70S BY LATE WEEK.
DISCUSSION
ISSUED AT 101 PM MDT SUN SEP 27 2026
AFTERNOON SATELLITE IMAGERY SHOWS INCREASING CLOUD COVER ACROSS
EASTERN IDAHO AS SOUTHWESTERLY FLOW STRENGTHENS AHEAD OF AN
APPROACHING UPPER-LEVEL TROUGH. TEMPERATURES HAVE CLIMBED INTO
THE 60S ACROSS LOWER ELEVATIONS AND WILL REACH THE 70S BEFORE
PEAK DIURNAL HEATING CONCLUDES. AS THE TROUGH AXIS APPROACHES
TONIGHT, CLOUD COVER WILL THICKEN, BRINGING A BRIEF RETURN OF
SHOWERS AND POTENTIAL ISOLATED THUNDERSTORMS TO THE EASTERN HALF
OF THE FORECAST AREA. THE HIGHEST PRECIPITATION PROBABILITIES
WILL ALIGN ALONG AND EAST OF THE I-15 CORRIDOR, WITH THE EASTERN
HIGHLANDS SERVING AS THE PRIMARY FOCUS AREA. THIS FEATURE WILL
MOVE THROUGH QUICKLY, WITH CLEARING CONDITIONS SPREADING ACROSS
THE REGION THROUGHOUT THE DAYTIME HOURS ON MONDAY. THE SYSTEM
WILL USHER IN A COOLER AIR MASS, DROPPING VALLEY HIGHS BACK INTO
THE 60S ON MONDAY—APPROXIMATELY 10 DEGREES BELOW TODAY'S
MAXIMUMS.
UPPER-LEVEL FLOW TRANSITIONS TO PREDOMINANTLY ZONAL TUESDAY
INTO WEDNESDAY AS HIGH PRESSURE BEGINS TO ORGANIZE OVER THE
SOUTHWESTERN U.S.. TEMPERATURES WILL HOVER NEAR SEASONAL
CLIMATOLOGICAL NORMS FOR THE FIRST PART OF THE WORKWEEK,
ACCOMPANIED BY DRY CONDITIONS AND LIGHT SURFACE WINDS. UPPER-
LEVEL RIDGING WILL BUILD DIRECTLY OVER THE INTERMOUNTAIN WEST
STARTING WEDNESDAY AND REMAIN ESTABLISHED THROUGH NEXT WEEKEND.
THIS WILL DRIVE A WARMING TREND THAT WILL PUSH AFTERNOON
TEMPERATURES ABOVE SEASONAL AVERAGES. HIGHS IN LOWER-ELEVATION
VALLEYS WILL REACH THE MID-TO-UPPER 70S BY THURSDAY AND HOLD
THERE THROUGH THE WEEKEND. WITH ATMOSPHERIC MOISTURE SHUNTED
WELL AWAY FROM THE REGION, THE FORECAST REMAINS COMPLETELY VOID
OF PRECIPITATION CHANCES BEYOND MONDAY, ENSURING A DRY,
PLEASANT START TO OCTOBER.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1014 PM MDT SUN SEP 27 2026
VFR CONDITIONS WILL LIKELY CONTINUE AT ALL SITES THROUGH THE
FORECAST PERIOD. MOISTURE SPREADING INTO THE REGION WILL ALLOW
FOR -SHRA/SHRA TO DEVELOP ACROSS THE REGION THIS EVENING AROUND
MIDNIGHT. WITH ANY HEAVIER SHOWERS, MVFR CONDITIONS ARE
POSSIBLE. THE BEST CHANCES FOR PREDOMINATE -SHRA/SHRA WILL BE
AT DIJ, PIH, AND IDA THIS EVENING INTO EARLY MORNING, BUT CARRY
VCSH AT ALL SITES. HAVE KEPT PROB30 FOR -TSRA FOR DIJ, PIH, AND
IDA FOR THIS EVENING AROUND MIDNIGHT. HOWEVER, -TSRA IS NOT
THAT LIKELY. PRECIPITATION SHIFTS EAST OF THE REGION DURING THE
MORNING MONDAY. EXPECT A BREAK IN PRECIPITATION BY EARLY TO MID
MORNING WITH ANOTHER CHANCE OF SHOWERS FOR PIH, IDA, SUN, AND
DIJ TOMORROW AFTERNOON. HAVE KEPT IN VCSH FOR PIH, IDA AND SUN
FOR TOMORROW AFTERNOON. THERE IS A SLIGHT CHANCE OF
THUNDERSTORMS TOMORROW AFTERNOON AS WELL. HAVE ADDED PREDOMINATE
SHOWERS AND A PROB30 FOR -TSRA FOR DIJ FOR TOMORROW AFTERNOON.
OTHER SITES MAY NEED A PROB30 FOR THUNDERSTORMS FOR TOMORROW
AFTERNOON AS WELL.
FIRE WEATHER
ISSUED AT 101 PM MDT SUN SEP 27 2026
MOISTURE STREAMING INTO EAST IDAHO WILL ALLOW FOR SHOWERS AND
ISOLATED THUNDERSTORMS OVERNIGHT. SLIGHTLY COOLER TEMPERATURES
ARRIVE MONDAY BEHIND THE DEPARTING SYSTEM. A SHALLOW RIDGE OF
HIGH PRESSURE BUILDS BACK INTO EAST IDAHO FOR MUCH OF THE WEEK,
WITH A GRADUAL WARMING TREND AND DRY CONDITIONS. MODELS HAVE
BACKED OFF ON A SYSTEM FOR THE WEEKEND AND ARE NOW JUST SWINGING
A WEAK SYSTEM PAST TO THE NORTH, SO PRECIPITATION CHANCES HAVE
LESSENED.
PIH WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...MCKAUGHAN
AVIATION...TW
FIRE WEATHER...DMH
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