747
FXUS65 KPIH 290522
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
1122 PM MDT FRI MAR 28 2025
KEY MESSAGES
- SHOWERS RETURN SATURDAY, WITH SNOW LEVELS LOWERING CLOSE TO
VALLEY FLOORS AROUND SUNRISE. SOME VALLEY LOCATIONS COULD SEE
A MIX OR A BRIEF CHANGE-OVER TO SNOW AT THAT TIME WITH VERY
LIGHT ACCUMULATIONS.
- A BRIEF RIDGE OF HIGH PRESSURE ON SUNDAY WILL KEEP CONDITIONS
MOSTLY DRY AHEAD OF A MORE ACTIVE PATTERN BUILDING IN FOR MUCH
OF NEXT WEEK WITH DAILY PRECIPITATION CHANCES RETURNING.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 109 PM MDT FRI MAR 28 2025
AIR QUALITY HAS IMPROVED FOLLOWING DUST INTRUSION FROM NEVADA
BEHIND COLD FRONT LAST NIGHT. WATER VAPOR SATELLITE IMAGERY
SHOWS TWO FEATURES OF NOTE. FIRST IS SHORTWAVE COMPLEX LIFTING
NORTHEAST OUT OF DESERT SOUTHWEST THROUGH NEVADA/UTAH, SPREADING
MID AND HIGH MOISTURE NORTH ACROSS THE SOUTHERN HALF OF THE
FORECAST AREA. A FEW LIGHT RADAR RETURNS ARE ASSOCIATED WITH
THIS FEATURE, EXPECTED TO WEAKLY FILL IN ACROSS THE SOUTHEAST
CORNER THIS AFTERNOON AND EVENING. THE SECOND FEATURE IS
SHORTWAVE LIFTING NORTHEAST THROUGH OREGON TOWARD THE IDAHO
PANHANDLE. THIS FEATURE ALREADY PRODUCING ISOLATED TO SCATTERED
SHOWERS ACROSS THE CENTRAL MOUNTAINS. THE SHOWER ACTIVITY WILL
CONTINUE TO DEVELOP THROUGH THE EVENING, AND IS EXPECTED TO
SPREAD INTO THE REMAINDER OF THE REGION ALONG THE DIVIDE. A
BRIEF BREAK WILL BE POSSIBLE OVERNIGHT BEHIND THIS SYSTEM.
BY EARLY SATURDAY MORNING, NEXT FEATURE EJECTS OUT OF PACIFIC
LOW TOWARD EAST IDAHO AS A WEAKLY CLOSED LOW. SHOWERS REDEVELOP
LATE FRIDAY NIGHT AND BEGIN SPREADING ACROSS EAST IDAHO. EXPECT
SNOW LEVELS TO LOWER TOWARD VALLEY FLOORS FRIDAY NIGHT. SOME
REGIONS COULD SEE SNOW LEVELS LOWER ENOUGH FOR RAIN TO MIX WITH
OR COMPLETELY CHANGE OVER TO SNOW AROUND SUNRISE AS SNOW. THE
BEST CHANCE FOR LIGHT ACCUMULATIONS AT VALLEY FLOORS COINCIDENT
WITH THE INCREASING CHANCES OF PRECIPITATION WILL OCCUR IN THE
EASTERN MAGIC VALLEY AND RAFT RIVER REGIONS. PROBABILISTIC 6HR
SNOWFALL ACCUMULATIONS SUPPORT UP TO 1" OF SNOWFALL AT THE 90TH
PERCENTILES. GIVEN THE RECENT WARM TEMPERATURES, THE GROUND MAY
BE TOO WARM TO SUPPORT MUCH ACCUMULATION WITH FORECAST LOWS
STILL JUST ABOVE FREEZING. TEMPERATURES ON SATURDAY COOL A FEW
MORE DEGREES FROM TODAY'S HIGHS, WITH SHOWERS BECOMING MORE
WIDESPREAD ACROSS EAST IDAHO THROUGHOUT THE DAY. SNOW LEVELS
RISE TO AN AVERAGE OF ABOUT 6000 FT ELEVATION ACROSS THE
FORECAST AREA, SO VALLEY RAIN/MOUNTAIN SNOW SHOULD BE THE RULE
FOR MOST AREAS. SHORTWAVE FEATURE SHIFTS EAST OVERNIGHT SATURDAY
NIGHT, PUSHING PRECIPITATION EAST THROUGH THE PERIOD.
LONG TERM /SUNDAY THROUGH FRIDAY/
ISSUED AT 109 PM MDT FRI MAR 28 2025
BEHIND ONE SHORTWAVE TROUGH, WE GET A VERY SHORT-LIVED BREAK IN OUR
ACTIVE PRECIPITATION PATTERN ON SUNDAY AS A WEAK, TRANSIENT RIDGE
PASSES THROUGH EASTERN IDAHO. HIGHS ON SUNDAY AND MONDAY WILL BE
NEARLY IDENTICAL, IN THE UPPER 40S AND LOW 50S ACROSS THE EASTERN
MAGIC VALLEY AND SNAKE RIVER PLAIN WITH MILD TEMPERATURES IN THE LOW
TO MID 40S IN OUR MID ELEVATION TOWNS. WHILE SUNDAY IS A DRIER DAY,
PRECIPITATION RETURNS ON MONDAY WITH VALLEY RAIN AND MOUNTAIN SNOW.
LOOKING TO MONDAY AND TUESDAY, IVT INCREASES AS WE TAP INTO SOME
MORE OF THE PACIFIC MOISTURE AVAILABLE, WITH THE NBM SHOWING ABOUT A
70 PERCENT CHANCE OF ALMOST ALL OF EASTERN IDAHO SEEING AT LEAST A
TENTH OF AN INCH OF QPF IN THE 48 HOURS FROM MONDAY MORNING TO
WEDNESDAY MORNING. IT ALSO SHOWS ABOUT A 20 TO 40 PERCENT CHANCE OF
A QUARTER INCH OF QPF IN THE EASTERN MAGIC VALLEY AND SNAKE RIVER
PLAIN FOR THE SAME TIME FRAME. TEMPERATURES WILL BE VERY NEAR
FREEZING ON TUESDAY MORNING, SO THERE IS ALSO THE POTENTIAL FOR SOME
LIGHT SNOWFALL IN THE VALLEYS, TOO, THOUGH WE'RE TALKING SNOW TOTALS
GENERALLY LESS THAN AN INCH. IN THAT 48-HOUR TIME RANGE, WE MAY BE
LOOKING AT SOME LOW-END WINTER WEATHER ADVISORY LEVEL SNOWFALL FOR A
FEW OF OUR MOUNTAIN PASSES (ABOUT 6" OF SNOW), PARTICULARLY IN THE
EASTERN HIGHLANDS, THOUGH IT'S STILL A LITTLE TOO EARLY TO COMMIT TO
THOSE SNOW TOTALS. HIGHS REMAIN IN THE 40S FOR WEDNESDAY AND
THURSDAY AS OUR ACTIVE PATTERN CONTINUES. BREEZY WINDS ARE EXPECTED
EACH AFTERNOON, TOO, WITH GUSTS OF 25 TO 35 MPH. IT LOOKS LIKE GUSTS
WILL BE A BIT STRONGER ON TUESDAY AFTERNOON, PUSHING CLOSER TO 40 OR
EVEN 45 MPH IN THE EASTERN MAGIC VALLEY AND LOWER SNAKE RIVER PLAIN.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1122 PM MDT FRI MAR 28 2025
FORECAST IS GENERALLY ON TRACK WITH SKIES MODESTLY CLEARING AND
ISOLATED SHOWERS DIMINISHING. THIS WILL SUPPORT SEVERAL HOURS OF
CONDITIONS TECHNICALLY A BIT CLEARER THAN WHAT IS REFLECTED IN THE
TAFS OVERNIGHT, BUT CLOUDS WILL INCREASE FROM THE WEST BACK TO
SCATTERED VFR BY DAYBREAK. OUR NEXT CHANCE OF PRECIPITATION REMAINS
ON TRACK TO ARRIVE WITH AN APPROACHING SHORTWAVE SATURDAY. REVIEWING
A FRESH SUITE OF THE HIGH-RES HREF CAMS LATE THIS EVENING,
CONFIDENCE REMAINS LOW ON BONAFIDE PRECIP OCCURRING AT MOST SITES,
SO JUST CONTINUED TO REFINE TIMING OF VCSH AND TWEAKED CIGS IN THE
06Z TAFS THAT WERE JUST ISSUED...GENERALLY NUDGING THE START TIME OF
SHOWERS AN HOUR OR SO LATER AT MOST TERMINALS COMPARED TO THE 00Z
TAFS. CONFIDENCE IN -SHRA HAS PERHAPS INCREASED/SOLIDIFIED SLIGHTLY
AT KBYI SO STAYING THE COURSE THERE. STILL SEEING PERHAPS A 10%
CHANCE OF A BRIEF SWITCH TO OR MIX WITH -SN AT KBYI SATURDAY MORNING
TOO, BUT THE BULK OF GUIDANCE IS LIKELY JUST WARM ENOUGH (EVEN WHEN
WET-BULBING OUT IN A SATURATED COLUMN) TO KEEP PRECIP TYPE AS RAIN.
OVERALL SHOWER POTENTIAL STARTS AT 14Z/8AM AT KSUN AND KBYI, AND
THEN HOLDS OFF UNTIL 18-20Z/12-2PM AT KPIH/KIDA/KDIJ, CONTINUING
THROUGH THE AFTERNOON WITH LIKELY SOME HELP FROM DIURNAL HEATING. NO
GUIDANCE CURRENTLY SUPPORTS ANYTHING LOWER THAN VFR CIGS/VSBYS FOR
THESE THREE LATTER TERMINALS AT THIS TIME (SO EXPECTING THIS TO BE A
LOW-IMPACT SHORTWAVE), ALTHOUGH WE'LL HAVE TO REEVALUATE KDIJ LATE
SATURDAY NIGHT (JUST BEYOND THE END OF THE CURRENT TAF PERIOD) FOR
PERHAPS SOME LINGERING MOISTURE OR LOWER CIGS. HREF MUCAPE DOESN'T
EXCEED 100 J/KG AND UNEDITED NBM PROBS DON'T SUPPORT THUNDER, SO
FEELING REASONABLE CONFIDENCE IN KEEPING THUNDER OUT OF THE PICTURE
TOO. FINALLY, A SW CROSSWIND AT UP TO 10KTS IS FORECAST SATURDAY
AFTERNOON AT KSUN (HINTED AT IN MOS GUIDANCE, WHICH...BELIEVE IT OR
NOT...STILL DOES A DECENT JOB AT PICKING UP ON OUR SW WIND DAYS IN
THE WOOD RIVER VALLEY). LOOKING AHEAD, SUNDAY SO FAR IS LOOKING
DRIER AND VFR WITH SOME MID TO HIGH-LEVEL CLOUD COVER.
HYDROLOGY
ISSUED AT 109 PM MDT FRI MAR 28 2025
TEMPERATURES HAVE COOLED ENOUGH ACROSS EAST IDAHO BEHIND THE
PASSAGE OF THE COLD FRONT LAST NIGHT TO SIGNIFICANTLY SLOW THE
LOW AND MID-ELEVATION SNOW MELT AND RUNOFF. ALTHOUGH SHOWERS ARE
EXPECTED THROUGH THE WEEKEND INTO NEXT WEEK, TEMPERATURES ARE
ALSO EXPECTED TO CONTINUE A SLOW DECLINE, WITH OVERNIGHT LOWS
FORECAST TO DROP TO AROUND OR JUST ABOVE FREEZING, INCLUDING AT
LOWER ELEVATIONS. THIS SHOULD FURTHER MITIGATE THE ACCELERATED
RUNOFF OF THE PREVIOUS WARM SPELL. LOCALIZED IMPACTS WILL STILL
BE POSSIBLE, BUT WIDESPREAD IMPACTS ARE NOT ANTICIPATED.
THEREFORE, THE HYDROLOGIC OUTLOOK WILL NOT BE UPDATED TODAY.
PIH WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...DMH
LONG TERM...AMM
AVIATION...KSMITH
HYDROLOGY...DMH
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