018
FXUS66 KPDT 232035
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
135 PM PDT TUE JUN 23 2026
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 /18Z TAFS THROUGH 18Z WEDNESDAY/
VFR CONDITIONS WILL PERSIST THROUGH THE PERIOD WITH LIGHT WINDS
LESS THAN 12 KNOTS FOR ALL TAF SITES UNTIL 22-23Z. AFTER 22-23Z,
RDM/BDN WILL SEE AN INCREASE IN WINDS OF 10-13G17-21KT BEFORE
SETTLING TO 10KTS AFTER 01-04Z RESPECTIVELY. NO CIG OR VIS
ISSUES EXPECTED.
FIRE WEATHER
HOT, DRY, AND LOCALLY BREEZY NORTHEAST WINDS (10-20 MPH WITH
HIGHER GUSTS) ARE ONGOING OR EXPECTED TODAY, MAINLY ACROSS
OR691 (LOWER COLUMBIA BASIN OF OREGON), AND A RED FLAG WARNING
REMAINS IN EFFECT UNTIL 8 PM PDT THIS EVENING. THE MAIN AREA OF
CONCERN IS ACROSS NORTH-CENTRAL OREGON COVERING MUCH OF THE
HIGHER TERRAIN OF WASCO, SHERMAN, GILLIAM, AND MORROW COUNTIES
WHERE 12Z HREF AND REFS GUIDANCE BOTH SHOW 60-100 PERCENT
PROBABILITIES OF REACHING WIND AND RELATIVE HUMIDITY THRESHOLDS
OF 15 MPH AND 20 PERCENT, RESPECTIVELY. FIRE WEATHER CONCERNS
ARE LOWER (20-50 PERCENT CONFIDENCE IN REACHING WIND/RH
THRESHOLDS) ELSEWHERE ACROSS THE LOWER COLUMBIA BASIN.
THIS AFTERNOON AND EVENING THERE IS A VERY LOW (5-15 PERCENT)
CHANCE OF HIGH-BASED SHOWERS AND THUNDERSTORMS ACROSS THE OREGON
CASCADES AND PORTIONS OF THE BLUE MOUNTAINS.
WEDNESDAY, WINDS ARE ANTICIPATED TO FLIP TO ONSHORE (WESTERLY)
AND BECOME BREEZY DURING THE MID/LATE AFTERNOON HOURS AS A WEAK
SHORTWAVE TROUGH MOVES OVER THE PACIFIC NORTHWEST. 12Z HREF AND
REFS GUIDANCE SHOW MEDIUM-HIGH PROBABILITIES (40-80 PERCENT) IN
REACHING RED FLAG CRITERIA ACROSS THE MAJORITY OF OR691 WITH
LESSER COVERAGE FOR WA691 (LOWER COLUMBIA BASIN OF WASHINGTON)
AND WA690 (KITTITAS VALLEY). HAVE HELD OFF ON ISSUING ANY FIRE
WEATHER HEADLINES TO AVOID CONFUSION WITH THE EXISTING RFW IN
EFFECT TODAY.
THERE IS A SLIGHT CHANCE (10-25 PERCENT) OF SHOWERS AND
THUNDERSTORMS ACROSS THE CASCADES AS WELL AS THE BLUE MOUNTAINS
ON WEDNESDAY.
THURSDAY, FIRE WEATHER CONCERNS BECOME WIDESPREAD ACROSS OR691,
WA691, AND WA690 AS BREEZY TO WINDY WESTERLY WINDS (15-25 MPH
WITH HIGHER GUSTS) OVERLAP WITH LOW RELATIVE HUMIDITY (10-20
PERCENT). 12Z REFS AND NBM PROBABILITIES PAINT A 50-90 PERCENT
CHANCE OF REACHING RFW CRITERIA. FIRE WEATHER HEADLINES ARE
LIKELY, BUT AS WITH THE CONCERNS FOR WEDNESDAY HAVE HELD OFF
ISSUING ANY FIRE WEATHER HEADLINES TO AVOID CONFUSION WITH THE
EXISTING RFW IN EFFECT TODAY.
PRELIMINARY POINT TEMPS/POPS
PDT 56 92 59 86 / 0 0 0 0
ALW 61 93 64 88 / 0 0 0 0
PSC 59 96 61 90 / 0 0 0 0
YKM 61 95 59 88 / 0 0 10 0
HRI 58 95 63 88 / 0 0 0 0
ELN 60 91 59 82 / 0 10 10 0
RDM 52 88 48 83 / 0 0 10 0
LGD 54 89 54 86 / 10 0 0 0
GCD 52 91 52 87 / 0 0 0 0
DLS 64 94 62 84 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...RED FLAG WARNING UNTIL 8 PM PDT THIS EVENING FOR ORZ691.
DISCUSSION...86
AVIATION...90
FIRE WEATHER...86
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