147
FXUS66 KPDT 312259
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
359 PM PDT FRI JUL 31 2026
KEY MESSAGES
- EXTREME FIRE WEATHER CONCERNS SATURDAY.
*RED FLAG WARNINGS ISSUED*
*PARTICULARLY DANGEROUS SITUATION (PDS) RED FLAGS ISSUED*
- WINDY CONDITIONS SATURDAY.
*WIND ADVISORIES ISSUED*
- DRY CONDITIONS RETURN EARLY NEXT WEEK.
DISCUSSION
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWS DRY CONDITIONS
UNDER SMOKY SKIES FOR MUCH OF THE REGION. THIS IS IN RESPONSE TO
A TRANSIENT UPPER LEVEL RIDGE BUILDING TODAY IN THE WAKE OF THE
PASSING SHORTWAVE THAT BROUGHT ADDITIONAL CLOUD COVER AND BREEZY
WINDS YESTERDAY. THE RIDGE IS SHORT-LIVED AND IS IN FRONT OF A
ROBUST UPPER LEVEL LOW PRESSURE SYSTEM THAT WILL MOVE ONSHORE
OVER THE SOUTHERN BRITISH COLUMBIA COAST SATURDAY MORNING AND
AFTERNOON. A DRY COLD FRONT AT THE SURFACE IS ASSOCIATED WITH
THIS UPPER LEVEL LOW, AND WILL PASS THROUGH THE PACIFIC
NORTHWEST FROM NORTHWEST TO SOUTHEAST THROUGH THE AFTERNOON AND
EVENING. THIS FRONTAL PASSAGE IS MOVING INTO A VERY DRY AIR
MASS, AND WILL BRING WITH IT STRONG WINDS OUT OF THE WEST.
THESE PARAMETERS, COUPLED WITH ADDITIONAL INSTABILITY ASSOCIATED
WITH THE FRONTAL BOUNDARY AND PROLONGED ANTECEDENT DRY
CONDITIONS, WILL PROMOTE EXTREME FIRE WEATHER CONCERNS WHICH
COULD LEAD TO RAPID FIRE SPREAD FOR NEW AND EXISTING FIRES.
THUS, MULTIPLE RED FLAG WARNINGS HAVE BEEN ISSUED FROM 11 AM TO
11 PM ACROSS THE LOWER COLUMBIA BASIN, BLUE MOUNTAINS, CENTRAL
OREGON, JOHN DAY BASIN, GRANDE RONDE VALLEY, WALLOWA COUNTY,
PORTIONS OF THE EAST SLOPES OF THE OREGON CASCADES, AND THE
YAKIMA/KITTITAS VALLEYS. EXPECTED HIGH WINDS ACROSS THE LOWER
COLUMBIA BASIN, BLUE MOUNTAINS WALLOWA/UNION COUNTIES,
YAKIMA/KITTITAS VALLEYS, AND PORTIONS OF CENTRAL OREGON POSE A
PARTICULARLY DANGEROUS SITUATION (PDS) RELATED TO FIRE WEATHER
CONCERNS, WITH THE POTENTIAL FOR CATASTROPHIC IMPACTS RELATED TO
WILDFIRE SPREAD. THE NBM SUGGESTS A 60-90% CHANCE OF SUSTAINED
WINDS OF 25 MPH IN THESE AREAS, COUPLED WITH AFTERNOON
HUMIDITIES IN THE MID-TEENS. GUSTS ARE ALSO EXPECTED TO REACH
BETWEEN 35-55 MPH IN THESE AREAS. MAKE SURE TO STAY AWARE OF
THE WEATHER, AND HAVE MULTIPLE WAYS TO RECEIVE OR ATTAIN WEATHER
INFORMATION.
THE COLD FRONT WILL BRING STRONG WINDS TO THE AREA, WITH HIGHEST
WINDS EXPECTED TO OCCUR ACROSS THE KITTITAS VALLEY, SIMCOE
HIGHLANDS, BLUE MOUNTAIN FOOTHILLS, AND THE LOWER COLUMBIA
BASIN. SUSTAINED WINDS OF 25 TO 35 MPH WITH GUSTS UP TO 55 MPH
WILL BE POSSIBLE, PEAKING BETWEEN 3PM-7PM. THE GFS, SREF, AND
NAM ALL ADVERTISE A PRESSURE GRADIENT OF 10-13MB BETWEEN
PORTLAND AND SPOKANE, WHICH PROVIDES ADDITIONAL CONFIDENCE IN
THE WIND FORECAST. WINDS WILL STAY ELEVATED THROUGH THE
REMAINDER OF THE EVENING BEFORE SUBSIDING AROUND MIDNIGHT AND
CONTINUING TO DROP OVERNIGHT.
CONDITIONS MODERATE ON SUNDAY AS A COOLER AND LESS DRY AIRMASS
BRIEFLY MOVES OVER THE REGION BEHIND THE EXITING COLD FRONT AND
UPPER LEVEL LOW/TROUGH. AN UPPER LEVEL HIGH PRESSURE BUILDS
ALONG THE COAST TO ALLOW FOR A THERMAL TROUGH TO DEVELOP. THIS
WILL BRING IN A MUCH DRIER AIRMASS ON MONDAY, DROPPING AFTERNOON
HUMIDITIES INTO THE LOW TO MID-TEENS ACROSS CENTRAL OREGON -
EXTENDING ACROSS THE COLUMBIA BASIN BY TUESDAY. DIURNALLY BREEZY
WINDS WILL RESULT EACH DAY OVER THE CRITICALLY DRY AIRMASS,
WHICH MAY WARRANT THE ISSUANCE OF FIRE WEATHER PRODUCTS OVER
CERTAIN AREAS. 75
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
VFR CONDITIONS PREVAIL WITH THE EXCEPTION OF BDN AND RDM WITH
ONGOING HAZE AND SMOKE ISSUES. LINGERING SMOKE AND HAZE
CONDITIONS ACROSS THE REGION WILL BRING SMALL CHANCES (5 TO 15
PERCENT) THROUGH THE REST OF THE PERIOD. GUSTY/BREEZY WINDS WILL
DEVELOP TOMORROW MORNING THROUGH THE AFTERNOON HOURS, PERSISTING
THROUGH THE REST OF THE PERIOD. GUSTS IN SOME PLACES COULD REACH
UP TO 30 TO 40 MPH AT TIMES.
FIRE WEATHER
RED FLAG WARNINGS HAVE BEEN ISSUED FOR 11 AM TO 11 PM SATURDAY
FOR FIRE WEATHER ZONES WA690-694 AND OR 691-704. A PARTICULARLY
DANGEROUS SITUATION (PDS) RED FLAG HAS BEEN ISSUED FOR
WA690-WA693, OR691-OR696, AND OR700 BETWEEN 2 PM AND 8 PM. THESE
ZONES INCLUDED IN THE PDS COULD EXPERIENCE EXTREME FIRE WEATHER
RESULTING IN RAPID FIRE GROWTH FOR NEW AND EXISTING FIRES. THE
ECMWF SUGGESTS 700MB WINDS OF UP TO 50KTS IN THE BASIN WITH
40-45KTS THROUGH CENTRAL OREGON. THESE ELEVATED WINDS ARE MOVING
INTO AN AIRMASS WITH PRECIPITABLE WATER AMOUNTS OF
0.4-0.6",60-80% OF NORMAL, WHICH SHOULD ALLOW FOR THESE WINDS TO
BE MORE EFFICIENT AT MIXING TO LOWER ELEVATIONS. GUIDANCE HAS
ALSO STRUGGLED WITH THIS UNSEASONAL WEATHER PATTERN, AS
OBSERVATIONS HIGHLIGHT A HIGHER BIAS RELATED TO MODEL DATA.
THUS, A TREND TOWARD DRIER AND WINDIER CONDITIONS IS POSSIBLE
OVER THE NEXT 12 HOURS. 75
PRELIMINARY POINT TEMPS/POPS
PDT 62 84 47 78 / 0 0 0 0
ALW 67 87 52 79 / 0 0 0 0
PSC 64 91 51 83 / 0 0 0 0
YKM 62 87 51 82 / 0 0 0 0
HRI 66 86 52 81 / 0 0 0 0
ELN 60 78 49 75 / 0 0 0 0
RDM 52 84 40 79 / 0 0 0 0
LGD 60 88 48 79 / 0 0 0 0
GCD 57 92 49 82 / 0 0 0 0
DLS 64 80 56 80 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...RED FLAG WARNING FROM 11 AM TO 11 PM PDT SATURDAY FOR
WAZ690>693.
WIND ADVISORY FROM 11 AM TO 11 PM PDT SATURDAY FOR WAZ024-
026>029-521.
AIR QUALITY ALERT UNTIL 2 PM PDT MONDAY FOR WAZ028>030.
OR...RED FLAG WARNING FROM 11 AM TO 11 PM PDT SATURDAY FOR
ORZ691>704.
WIND ADVISORY FROM 11 AM TO 11 PM PDT SATURDAY FOR ORZ041-044-
507-508-510.
AIR QUALITY ALERT UNTIL 2 PM PDT MONDAY FOR ORZ044-049-050-502-
503-505>511.
DISCUSSION...75
AVIATION...95
FIRE WEATHER...77
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