457
FXUS66 KPDT 122102
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
202 PM PDT SUN APR 12 2026
KEY MESSAGES
- SHOWERS TODAY, WITH LOW THUNDERSTORM CHANCES, MAINLY OVER
EASTERN AREAS.
- THE NEXT SYSTEM WILL BRING RAIN TO THE LOWER ELEVATIONS AND
SNOW TO THE MOUNTAINS WEDNESDAY INTO THURSDAY.
- TEMPERATURES WILL BE ABOUT 5 TO 10 DEGREES BELOW NORMAL
WEDNESDAY AND THURSDAY BEFORE RISING TO NEAR AND POSSIBLY
ABOVE NORMAL LATER IN THE WEEK.
DISCUSSION
AN UPPER LEVEL LOW CURRENTLY OVER NORTHERN CALIFORNIA WILL
WEAKEN AND GRADUALLY MOVE INLAND THROUGH TONIGHT. THE BROADER
UPPER TROUGH WILL ALSO MOVE EASTWARD THROUGH MONDAY, WITH THE
AXIS OF THE TROUGH OVER THE GREAT BASIN BY MONDAY NIGHT. UNTIL
THE TROUGH IS EAST OF THE PACIFIC NORTHWEST, UNSETTLED
CONDITIONS WILL CONTINUE.
LATEST RADAR IMAGERY SHOWED A LARGE AREA OF SHOWERS, WITH SOME
EMBEDDED THUNDERSTORMS OVER EXTREME SOUTHEASTERN OREGON AND
SOUTHWESTERN IDAHO. GUIDANCE HAS THIS AREA SLOWLY PIVOTING
NORTHWARD AND MORE DEVELOPING NORTHWESTWARD AROUND THE LARGER
CIRCULATION AND THROUGH THE REMAINDER OF TODAY AND INTO TONIGHT.
AS THIS AREA MOVES NORTHWARD, DECENT QPF IS FORECAST ACROSS THE
BLUE MOUNTAINS AND POINTS EASTWARD THROUGH MONDAY MORNING.
LINGERING QPF IS STILL EXPECTED OVER EASTERN AREAS ON MONDAY,
BUT WITH THE TROUGH MOVING OUT OF THE REGION, CONDITIONS SHOULD
BEGIN TO IMPROVE BY LATER MONDAY AND DRYING IS EXPECTED ACROSS
MOST OF THE REGION, WHICH WILL CONTINUE INTO TUESDAY.
HOWEVER, BY LATER TUESDAY INTO WEDNESDAY PRECIPITATION CHANCES
INCREASE AS A LOW DROPS INTO THE PACIFIC NORTHWEST FROM CANADA.
THIS LOW WILL BRING COLDER AIR AND TEMPERATURES WILL BE ABOUT 5
TO 10 DEGREES COLDER THAN NORMAL WEDNESDAY AND THURSDAY.
OVERNIGHT LOWS WEDNESDAY NIGHT AND THURSDAY NIGHT LOOK TO BE
QUITE CHILLY WITH TEMPERATURES BELOW FREEZING IN THE YAKIMA AND
KITTITAS VALLEYS AND CLOSE TO FREEZING ALONG PORTIONS OF THE
FOOTHILLS OF THE NORTHERN BLUE MOUNTAINS. NBM PROBABILITIES OF
LOW TEMPERATURES <=32 DEGREES ARE 80 TO 90 PERCENT ON BOTH THESE
MORNINGS.
FURTHERMORE, THERE WILL BE BREEZY DIURNAL WINDS EACH DAY THROUGH
WEDNESDAY, IN THE CASCADE GAPS AND PORTIONS OF THE COLUMBIA
BASIN AND FOOTHILLS OF THE SOUTHERN BLUE MOUNTAINS. WINDS COULD
GUST IN THE 30 TO 35 MPH RANGE AND POSSIBLY AS HIGH AS 40 MPH.
ADDITIONALLY, THE LOW WILL BRING AT LEAST SOME PRECIPITATION TO
ALL AREAS, WITH RAIN IN THE LOWER ELEVATIONS (GENERALLY 0.15
INCHES OR LESS) AND SNOW IN THE MOUNTAINS. SNOW LEVELS WILL DROP
FROM ABOVE 4000 FEET ON WEDNESDAY TO BELOW PASS LEVEL BY
THURSDAY MORNING. THERE IS THE POTENTIAL FOR APPRECIABLE SNOW,
ESPECIALLY ABOVE 5000 FEET, BUT THERE ARE MANY CAVEATS AS WELL,
INCLUDING THE TIME OF YEAR AND THE FACT THAT ANY SNOW THAT FALLS
DURING THE DAY HAS A MUCH MORE DIFFICULT TIME ACCUMULATING OR IS
VERY WET IN MID-APRIL AND THE GROUND IS WARM.
THIS SYSTEM WILL MOVE OUT OF THE REGION BY LATER THURSDAY AND
AND RIDGING BUILDS BACK IN BRINGING DRY CONDITIONS FOR THE END
OF THE WEEK INTO THE WEEKEND. ANOTHER LOW MAY APPROACH THE
PACIFIC NORTHWEST FOR SUNDAY.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
A BAND OF PRECIPITATION IS LIKELY (60-80 PERCENT CHANCE) TO
BRING LIGHT RAIN TO RDM/BDN/PDT/ALW TODAY INTO TONIGHT WITH
LOWER (30-50 PERCENT) CHANCES AT DLS/PSC/YKM. WITHIN THE BAND,
SUB-VFR CIGS/VSBYS WILL BE POSSIBLE, BUT CONFIDENCE IN
OCCURRENCE WAS TOO LOW (LESS THAN 50 PERCENT) TO INCLUDE A
MENTION IN THE 18Z TAFS.
WINDS WILL INCREASE IN MAGNITUDE FROM THE WEST THIS AFTERNOON
AND PERSIST THROUGH THE PERIOD AT CLIMATOLOGICALLY WINDY
LOCATIONS SUCH AS PDT AND DLS.
PRELIMINARY POINT TEMPS/POPS
PDT 44 59 37 58 / 80 40 0 10
ALW 46 59 41 58 / 80 50 10 10
PSC 48 67 41 61 / 50 10 0 10
YKM 43 64 36 58 / 30 0 0 10
HRI 46 63 39 61 / 60 10 0 0
ELN 42 56 36 52 / 20 0 0 20
RDM 34 54 28 56 / 50 10 0 0
LGD 40 53 34 57 / 100 80 20 10
GCD 37 51 31 56 / 100 80 10 10
DLS 46 60 41 58 / 30 10 0 20
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...77
AVIATION...86
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page