415
FXUS66 KPDT 240527
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1027 PM PDT TUE JUN 23 2026
.UPDATED AVIATION DISCUSSION.
KEY MESSAGES
- RED FLAG WARNING IN EFFECT TODAY FOR THE LOWER COLUMBIA BASIN
OF OREGON (OR691)
- HOT, DRY, AND BREEZY WEDNESDAY, THEN WARM, DRY AND BREEZY TO
WINDY THURSDAY WITH CONTINUED FIRE WEATHER CONCERNS
- COOLER, WETTER WEATHER PATTERN LIKELY (90 PERCENT CONFIDENCE)
FRIDAY INTO THE WEEKEND
DISCUSSION
WATER VAPOR IMAGERY SHOWS A SHORTWAVE FROM THE PACIFIC
APPROACHING THE OR/WA COAST EARLY THIS AFTERNOON. CIRRUS IS
OVERSPREADING THE FORECAST AREA IN ADVANCE OF THE WAVE, AND A
CUMULUS FIELD IS DEVELOPING OVER THE CENTRAL OREGON CASCADES AND
HIGHER TERRAIN OF THE BLUE MOUNTAINS. AS THE SHORTWAVE MOVES
OVERHEAD LATER THIS AFTERNOON THROUGH THE EVENING, THERE IS A
VERY LOW TO SLIGHT CHANCE (5-15 PERCENT) OF HIGH-BASED SHOWERS
AND THUNDERSTORMS ACROSS THE CASCADES, BLUES, AND BLUE MOUNTAIN
FOOTHILLS.
LOCALLY BREEZY NORTHEASTERLY WINDS (10-20 MPH WITH HIGHER GUSTS)
COUPLED WITH LOW RELATIVE HUMIDITY (10-20 PERCENT) HAVE PROMPTED
A RED FLAG WARNING FOR OR691 (LOWER COLUMBIA BASIN OF OREGON)
THROUGH 8 PM PDT THIS EVENING (SEE FIRE WEATHER SECTION BELOW
FOR ADDITIONAL DETAILS).
THE HEAT ADVISORY THAT WAS IN EFFECT FOR THE EASTERN COLUMBIA
RIVER GORGE OF OREGON AND WASHINGTON TODAY WAS CANCELLED AS
TEMPERATURES HAVE BEEN A FEW DEGREES COOLER THAN PREVIOUSLY
ANTICIPATED, LOWERING THE OVERALL RISK OF HEAT-RELATED IMPACTS.
THAT SAID, WIDESPREAD MODERATE (LEVEL 2 OF 4) HEATRISK IS STILL
FORECAST ACROSS THE LOWER ELEVATIONS OF THE FORECAST AREA TODAY
AND TOMORROW. THIS LEVEL OF HEAT PRIMARILY AFFECTS THOSE WHO
ARE SENSITIVE TO HEAT, ESPECIALLY THOSE WITHOUT
COOLING/HYDRATION.
WEDNESDAY, ANOTHER WEAK SHORTWAVE TROUGH IS EXPECTED TO MOVE
OVER THE FORECAST AREA. WHILE CONFIDENCE IN EXACT
LOCATION IS STILL UNCERTAIN, HAVE INCREASED POPS ACROSS THE
MOUNTAINS (CASCADES AND BLUES) AND YAKIMA/KITTITAS VALLEYS TO
ACCOUNT FOR A VERY LOW (5-14 PERCENT) TO SLIGHT CHANCE (15-24
PERCENT) OF HIGH-BASED SHOWERS AND THUNDERSTORMS DURING THE
AFTERNOON AND EVENING HOURS. THE BEST CHANCES WILL BE ALONG THE
HIGHER TERRAIN OF THE EAST SLOPES OF THE WASHINGTON CASCADES
(AWAY FROM THE CREST).
BREEZY WESTERLY WINDS IN TANDEM WITH LOW RELATIVE HUMIDITY WILL
FACILITATE ANOTHER ROUND OF FIRE WEATHER CONCERNS WEDNESDAY
AFTERNOON AND EVENING (SEE FIRE WEATHER SECTION BELOW FOR
DETAILS).
BY THURSDAY, THE CLOSED LOW CURRENTLY DEVELOPING IN THE GULF OF
ALASKA IS EXPECTED (90 PERCENT CONFIDENCE) TO MOVE SOUTHEAST
ALONG THE COAST OF BRITISH COLUMBIA AND SOUTHEAST ALASKA. A
SHORTWAVE WRAPPING AROUND THE BASE OF THE LOW IS FORECAST TO
MOVE INLAND OVER THE PACIFIC NORTHWEST DURING THE AFTERNOON.
BREEZY TO WINDY WESTERLY WINDS AND LOW RELATIVE HUMIDITY ARE
ANTICIPATED AND FIRE WEATHER HEADLINES MAY BE NEEDED (SEE FIRE
WEATHER SECTION BELOW FOR DETAILS).
A TRANSITION TO A COOLER, WETTER PATTERN IS LIKELY (90 PERCENT
CONFIDENCE) BY THURSDAY NIGHT AS A SECOND SHORTWAVE MOVES
OVERHEAD, FOLLOWED BY THE PARENT CLOSED LOW OVER THE WEEKEND.
CLUSTER ANALYSIS OF 00Z ENSEMBLE MEMBERS SHOWS RELATIVELY SMALL
DIFFERENCES IN TIMING/LOCATION AND MAGNITUDE OF THE LOW DURING
THE PERIOD, SO CONFIDENCE IS HIGH IN THE CURRENT FORECAST OF
BELOW-NORMAL TEMPERATURES FRIDAY THROUGH THE WEEKEND. HOWEVER,
EVEN SMALL DIFFERENCES IN THE TRACK/TIMING OF THE LOW CAN HAVE A
SIGNIFICANT IMPACT ON PRECIPITATION SO STAY TUNED AS DETAILS
BECOME CLEARER.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
VFR CONDITIONS CURRENTLY AT ALL SITES, WHICH WILL STAY THE
COURSE THROUGH THE PERIOD. WINDS WILL INCREASE LATE MORNING FOR
KDLS/KPDT/KRDM/KBDN BETWEEN 15-25KTS. ELSEWHERE WINDS WILL STAY
LIGHT AND BELOW 10 KTS. 25KFT BKN CEILINGS WILL DEVELOP
WEDNESDAY EVENING AHEAD OF A WEAK SYSTEM. 75
PRELIMINARY POINT TEMPS/POPS
PDT 56 92 60 85 / 0 0 0 0
ALW 61 93 64 87 / 0 0 0 0
PSC 59 96 62 90 / 0 0 0 0
YKM 61 95 61 88 / 0 10 10 0
HRI 58 95 63 88 / 0 0 0 0
ELN 60 91 60 82 / 0 20 10 0
RDM 52 88 49 82 / 0 0 10 0
LGD 54 89 56 85 / 10 0 0 0
GCD 52 91 53 86 / 0 0 0 0
DLS 64 95 63 83 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...86
AVIATION...75
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