463
FXUS66 KPDT 291120
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
420 AM PDT FRI MAY 29 2026
KEY MESSAGES
- BREEZY TO LOCALLY GUSTY WINDS THROUGH THE CASCADE GAPS AND
ACROSS THE COLUMBIA BASIN TODAY
- NEAR TO BELOW NORMAL TEMPERATURES THROUGH THE WEEKEND
- DRY CONDITIONS WITH LIGHT WINDS INTO THE MIDDLE OF NEXT WEEK
DISCUSSION
TODAY: CONVECTIVE ACTIVITY HAS COME TO AN END
ACROSS THE PACNW TONIGHT, WITH LINGERING LIGHT SHOWERS STILL
HANGING ON ACROSS THE CENTRAL WA AND OR CASCADE CREST WITH
CLEAR/DRY CONDITIONS ACROSS THE REMAINDER OF THE FORECAST AREA.
OTHERWISE, QUIET CONDITIONS HAVE DEVELOPED ACROSS MUCH OF THE
FORECAST AREA, EXCEPT FOR BREEZY WINDS THAT HAVE DEVELOPED
THROUGH THE CASCADE GAPS.
TODAY, THE UPPER LOW/TROUGH OVER THE GREAT BASIN WILL SWING
NORTHEAST INTO THE CENTRAL/NORTHERN ROCKIES, PULLING THE TROUGH
AXIS AND AN AREA OF DIFFLUENCE ALOFT OVER THE FORECAST AREA.
THIS WILL REVITALIZE ISOLATED TO SCATTERED SHOWERS ACROSS THE
CASCADE EAST SLOPES, CENTRAL OR, AND THE YAKIMA/KITTITAS VALLEYS
THIS MORNING, WITH SHOWER ACTIVITY SPREADING ACROSS THE EASTERN
MOUNTAINS BY THIS AFTERNOON. ISOLATED THUNDERSTORMS WILL ALSO
BE POSSIBLE ACROSS THE EASTERN MOUNTAINS AS SURFACE INSTABILITY
(250-500 J/KG) AND LOW LEVEL LAPSE RATES (8-9.5 C/KM) INCREASE
IN THE AFTERNOON. OTHERWISE, A SURFACE PRESSURE GRADIENT SETTING
UP OVER THE CASCADE CREST WILL PRODUCE PERSISTENT BREEZY WINDS
THROUGH THE CASCADE GAPS AND ACROSS THE COLUMBIA BASIN, WITH THE
STRONGEST WINDS (25-35MPH WITH GUSTS 45-55MPH) DEVELOPING
THROUGH THE KITTITAS VALLEY THIS AFTERNOON AND EVENING.
SATURDAY THROUGH TUESDAY: OVER THE WEEKEND, THE UPPER LOW WILL
SLOWLY SWING NORTHWARD ACROSS THE NORTHERN ROCKIES, PLACING THE
REGION UNDER A COOL WESTERLY FLOW THAT WILL KEEP AFTERNOON
TEMPERATURES IN THE MID 60S TO MID 70S. CONDITIONS WILL REMAIN
DRY ACROSS THE FORECAST AREA THROUGH THIS PERIOD WHILE WINDS
WILL BECOME LIGHT AS THE CASCADE CREST PRESSURE GRADIENT BREAKS
DOWN. THERE IS, HOWEVER, A LOW CHANCE (<10%) FOR ISOLATED LIGHT
SHOWERS TO DEVELOP ACROSS THE MOUNTAINOUS TERRAIN ACROSS WALLOWA
COUNTY AS MOISTURE ATTEMPTS TO WRAP AROUND THE UPPER LOW TO THE
EAST.
BY MONDAY, A WEAK UPPER RIDGE WILL BUILD OVER THE PACNW AS THE
LOW LIFTS INTO CANADA, CONTINUING THE DRY AND WEAK WIND TREND
ACROSS THE FORECAST AREA. THE RIDGE OVERHEAD WILL ALSO PROMOTE A
WEAK WARMING TREND THAT WILL BRING LOWER ELEVATION TEMPERATURES
BACK INTO THE LOWER TO MID 80S BY TUESDAY (CONFIDENCE 60-75%).
WEDNESDAY AND THURSDAY: ENSEMBLE CLUSTER GUIDANCE IS IN GOOD
AGREEMENT THAT A SHORTWAVE TROUGH EJECTING FROM AN UPPER LOW IN
THE NORTHEAST PACIFIC WILL SLIDE ACROSS THE PACNW WEDNESDAY,
PRODUCING LIGHT RAIN SHOWERS ACROSS THE MOUNTAINOUS TERRAIN AND
BREEZY CONDITIONS IN THE LOWER ELEVATIONS (CONFIDENCE 60-65%).
WEAK, BROAD RIDGING WILL THEN BUILD BACK OVER THE PACNW WITH
DRIER CONDITIONS AND LOCALLY BREEZY CONDITIONS FOR THURSDAY
(CONFIDENCE 50-60%). THAT SAID, THERE ARE SOME ENSEMBLE CLUSTER
MEMBERS (~20%) THAT FAVOR TROUGHING OVER THE PACNW, RESULTING IN
CONTINUED CHANCES OF SHOWERS ACROSS THE CASCADES, BLUES, AND
WALLOWAS FOR THURSDAY. LAWHORN/82
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
VFR CONDITIONS TO
PREVAIL THROUGH THE PERIOD. ANOTHER ROUND OF SHOWERS WILL MAINLY
IMPACT THE MOUNTAINS THROUGH THE PERIOD, BUT SITES RDM/BDN WILL
SEE SHOWERS REDEVELOP THIS MORNING. SITE DLS WILL ALSO SEE
SHOWERS WITHIN VICINITY OF THE SITE THIS MORNING. WINDS WILL
INCREASE ACROSS MOST SITES THIS MORNING AND AFTERNOON AND
PERSIST THROUGH THE EVENING. WINDS WILL GENERALLY BE 12-17KTS
WITH GUSTS TO AROUND 25KTS AT SITES RDM/YKM/ALW/PSC; WINDS WILL
INCREASE TO 20-25KTS WITH GUSTS TO AROUND 35KTS AT SITES
DLS/PDT. LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 68 42 67 43 / 0 10 0 0
ALW 71 47 68 48 / 0 10 0 0
PSC 74 46 73 44 / 10 10 0 0
YKM 72 43 73 43 / 50 0 0 0
HRI 69 44 70 44 / 10 10 0 0
ELN 65 40 65 40 / 40 0 0 0
RDM 59 32 63 30 / 80 0 0 0
LGD 72 41 64 38 / 40 10 0 0
GCD 67 37 66 35 / 50 20 0 0
DLS 67 45 70 46 / 50 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY FROM 11 AM THIS MORNING TO 11 PM PDT THIS
EVENING FOR WAZ026.
OR...NONE.
DISCUSSION...82
AVIATION...82
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