217
FXUS65 KPIH 290820
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
220 AM MDT SAT MAR 29 2025
KEY MESSAGES
- A MIX OF RAIN/SNOW SHOWERS (~10-20% CHANCE OF THUNDERSTORMS
TODAY) ARE EXPECTED THROUGH SUNDAY WITH A CHANGEOVER TO ALL
SNOW EXPECTED TONIGHT INTO SUNDAY MORNING.
- A BRIEF RIDGE OF HIGH PRESSURE ON SUNDAY WILL BRING A RETURN
TO DRY CONDITIONS ACROSS THE SNAKE RIVER PLAIN AS SNOW SHOWERS
SHIFT INTO THE MOUNTAINS.
- DAILY PRECIPITATION CHANCES WILL CONTINUE FOR EARLY NEXT WEEK
AS A SERIES OF PACIFIC SYSTEMS SUPPORT A MIX OF RAIN/SNOW
SHOWERS AND NEAR NORMAL TO BELOW NORMAL TEMPERATURES.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED AT 220 AM MDT SAT MAR 29 2025
EARLY MORNING SATELLITE IMAGERY SHOWS A NEGATIVELY TITLED
TROUGH WORKING EAST THROUGH THE PACNW AND NORTHERN GREAT BASIN
AS DRY CONDITIONS PREVAIL ACROSS EASTERN IDAHO OUT AHEAD OF IT.
A MIX OF ISOLATED TO SCATTERED RAIN AND SNOW SHOWERS WILL BUILD
IN WEST TO EAST BEGINNING AFTER SUNRISE THIS MORNING WITH
PRECIPITATION EXPANDING EAST THROUGHOUT THE DAYTIME HOURS. GIVEN
ONLY ~100-300 J/KG OF MUCAPE, ANY THUNDERSTORM DEVELOPMENT WILL
REMAIN ISOLATED IN NATURE WITH THE LATEST HREF MODEL PROBABILITY
OF THUNDER SHOWING A 10-20% CHANCE ACROSS MUCH OF OUR CWA WITH
BEST CHANCES IN THE CENTRAL MOUNTAINS AND ALONG THE MONTANA
DIVIDE AND IDAHO/UTAH BORDER REGION.
AS THIS TROUGH WORKS DIRECTLY OVERHEAD TONIGHT, SNOW LEVELS
WILL FALL TO VALLEY FLOORS AS A COLDER AIRMASS BUILDS IN
OVERNIGHT, SUPPORTING OVERNIGHT LOWS AT OR BELOW FREEZING. THIS
WILL BRING ABOUT A CHANGEOVER TO ALL SNOW HEADING INTO SUNDAY
MORNING AS BEST CHANCES SHIFT FURTHER NORTH AND EAST AS THIS
TROUGH WORKS EAST OVER THE CONTINENTAL DIVIDE. PRECIPITATION
TOTALS WITH THIS EVENT WILL REMAIN LIGHT WITH SNOW TOTALS ACROSS
OUR LOWER ELEVATIONS FURTHER NORTH AND EAST AROUND A T-2" WITH
1-6" IN THE MOUNTAINS. ACROSS THE LOWER SNAKE RIVER PLAIN AND
EASTERN MAGIC VALLEY IS WHERE WE ARE EXPECTING PREDOMINANT RAIN
WITH MORE LIMITED SNOW POTENTIAL.
AS THIS TROUGH WORKS EAST INTO WYOMING ON SUNDAY, A BRIEF
TRANSITORY RIDGE OF HIGH PRESSURE WILL BUILD IN FROM THE WEST AS
BEST CHANCES FOR SNOW SHIFT INTO THE MOUNTAINS AS PREDOMINANT
DRY CONDITIONS RETURN ACROSS THE SNAKE RIVER PLAIN. THIS BREAK
IN PRECIPITATION FOR MOST ON SUNDAY WILL BE SHORT-LIVED HOWEVER
AS OUR NEXT SYSTEM QUICKLY BUILDS IN FROM THE WEST SUNDAY NIGHT
INTO MONDAY WITH ANOTHER ROUND OF WIDESPREAD RAIN AND SNOW
CHANCES.
TEMPERATURES THIS WEEKEND WILL REMAIN NEAR SEASONAL NORMS WITH
HIGHS IN THE 40S/50S AND LOWS IN THE 20S/30S. WINDS WILL ALSO
REMAIN BREEZY BOTH DAYS WITH GUSTS PEAKING EACH AFTERNOON AROUND
20-40 MPH, STRONGEST ACROSS THE SNAKE RIVER PLAIN AND EASTERN
MAGIC/RAFT RIVER VALLEY REGION.
LONG TERM /MONDAY THROUGH NEXT SATURDAY/
ISSUED AT 220 AM MDT SAT MAR 29 2025
MULTIPLE WEAKER SYSTEMS WILL BRING OCCASIONAL SHOWERS AND EVEN
A FEW THUNDERSTORMS OUR WAY THROUGH THE END OF NEXT WEEK. WE
WILL SEE A SHORT BREAK BETWEEN STORMS TUESDAY NIGHT/WEDNESDAY
BEFORE THE NEXT PERIOD OF MOISTURE BEGINS. AS WE HEAD INTO NEXT
WEEKEND, A BLOCKING PATTERN SETS UP OVER THE WESTERN STATES.
RIGHT NOW, THERE IS A PRETTY DECENT DIFFERENCE BETWEEN MODELS ON
WHERE THE LOW SETS UP SHOP. THE CLUSTER FORECASTS FIT NEATLY
INTO 3 CATEGORIES: NO CLOSED LOW (~25%), CLOSED LOW CENTERED
OVER NEVADA AND UTAH (~25%), AND CLOSED LOW NEAR THE FOUR
CORNERS (45-50%). THE GFS FITS INTO THE LAST SCENARIO, AND THE
ECMWF FITS THE SECOND ONE. THE FIRST "EVENT" FOR MONDAY-TUESDAY
YIELDS MOSTLY 6" OR LESS OF SNOW FOR THE MOUNTAINS. THE
EXCEPTIONS BEING THE SAWTOOTHS WHERE WE COULD SEE UPWARDS OF
9-10" IN SOME SPOTS, THE BEAR RIVER RANGE AND EASTERN HIGHLANDS
WHERE 10-16" ARE POSSIBLE ABOVE PASS LEVEL. LITTLE TO NO SNOW IS
FORECAST FOR LOWEST ELEVATIONS. SIMILARLY FOR WEDNESDAY-FRIDAY,
NO MUCH IF ANYTHING IMPACTFUL IS ANTICIPATED DOWN LOW. SNOW
AMOUNTS IN THE MOUNTAINS WILL BE ON THE LIGHT SIDE, WITH THE
SAWTOOTHS AND BEAR RIVER RANGE MAYBE HITTING 6". HIGH
TEMPERATURES MID-WEEK DIP DOWN INTO THE 40S FOR THE VALLEYS
BEFORE REBOUNDING A WEEK FROM NOW.
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.
PIH WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...MACKAY
LONG TERM...KEYES
AVIATION...KSMITH
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page