189
FXUS65 KPIH 291021
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
321 AM MST MON DEC 29 2025
KEY MESSAGES
- HIGH PRESSURE REBUILDS ACROSS THE WESTERN U.S.
- DRY CONDITIONS AND WARMER CONDITIONS THROUGH NEW YEAR'S EVE
- RAIN AND SNOW RINGS IN 2026
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED AT 1243 AM MST MON DEC 29 2025
DRY NORTHWEST FLOW REMAINS OVER EASTERN IDAHO TO END 2025. WE
SHOULD REMAIN DRY, ALTHOUGH WE WILL SEE SOME OCCASIONAL HIGH
AND MID LEVEL CLOUD COVER CROSSING OUR AREA. THE LOW LEVELS LOOK
TO REMAIN DRY ENOUGH TO PREVENT ANY ISSUES WITH FOG OR STRATUS,
BUT WE CANNOT COMPLETELY RULE OUT WITH TEMPERATURES DROPPING
OVERNIGHT. WHERE WE REMAIN WITHIN/ABOVE ANY INVERSION LAYER OR
WHERE WE STAYED "MIXED", HIGHS WILL BE IN THE UPPER 30S AND
40S. EXPECT OVERNIGHT LOWS TO BE ALL OVER THE PLACE, DEPENDING
ON LOCATION AND ELEVATION. AGAIN, WITHIN/ABOVE ANY INVERSION
LAYER OR WHERE WE STAY "MIXED", LOWS WILL REMAIN IN THE 20S.
OTHERWISE, LOOK FOR SINGLE DIGIT AND TEENS.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
ISSUED AT 1243 AM MST MON DEC 29 2025
THE 500MB UPPER LEVEL RIDGE OVER THE WESTERN STATES EASILY
REACHES HEIGHTS OF 5700M, HIGHLY ANOMALOUS FOR THIS TIME OF
YEAR; TO DO THAT WILL REQUIRE VERY WARM AIR. THERE IS AN
EASTWARD SHIFT THAT PUTS THE RIDGE AXIS OVERHEAD BY THU. BY
FRI(2 JAN) AFTERNOON THERE IS A RISK OF THE RIDGE BEGINNING TO
BREAK DOWN WITH 65 PERCENT OF THE SOLUTIONS MAKING UP THE
CLUSTERS OF MODEL RUNS THAT FEATURE THE BREAK-DOWN. FOR SAT, 45
PERCENT OF THE SOLUTIONS HAVE THE UPPER LEVEL RIDGE SUFFICIENTLY
BROKEN DOWN THAT PRECIPITATION IS LIKELY, WITH THE REMAINDER
HAVE THE LOW STILL TO THE WEST. SO NO MAJOR COLD FRONT IS
EXPECTED TO SWEEP THROUGH DURING THE PERIOD.
MOST OF THE SOLUTIONS HAVE SOUTHWEST UPPER LEVEL FLOW DEVELOPING
WITH THE SHIFTING OF THE RIDGE AXIS. THE SHIFT MEANS THE
TEMPERATURES ARE LIKELY TO RETURN TO BEING MILD FOR THE TIME OF YEAR
AND THE PATTERN IS VERY MUCH LIKE AN ATMOSPHERIC RIVER EVENT FOR FRI
AND THE REST OF THE WEEKEND. A LESS THAN 15 PERCENT OF THE SOLUTIONS
SHOW MORE ZONAL FLOW.
AVIATION /12Z TAFS THROUGH 12Z TUESDAY/
ISSUED AT 321 AM MST MON DEC 29 2025
EXPECT VFR WEATHER WITH MOSTLY MID AND HIGH LEVEL CLOUDS. THERE
ARE HINTS IN THE FORECAST FOR A LOW END POTENTIAL (20% AT BEST)
OF SEEING MVFR OR WORSE CONDITIONS AT TAF SITES OUTSIDE OF SUN.
IT IS DRY OUT THERE, BUT THAT IS ALLOWING OVERNIGHT TEMPERATURES
TO PLUMMET. THAT IS ENOUGH TO AT LEAST PLANT THE SEED, BUT NOT
ANYTHING THAT WOULD BE INCLUDED IN ANY TAFS AT THE MOMENT.
PIH WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM...KEYES
LONG TERM...MESSICK
AVIATION...KEYES
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