899
FXUS66 KPDT 181657
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
957 AM PDT TUE AUG 18 2026
KEY MESSAGES
- GUSTY WEST WINDS AND LOW RELATIVE HUMIDITY WILL COMBINE TO
CREATE CRITICAL FIRE WEATHER CONDITIONS THIS AFTERNOON,
MAINLY ACROSS THE COLUMBIA BASIN OF OREGON.
- ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS AND GUSTY WINDS
TOWARD THE OF THE WEEK, ASSOCIATED WITH AN UPPER LOW.
DISCUSSION
AN UPPER LEVEL SPLIT FLOW PATTERN IN PLACE TODAY WILL SHIFT
OVER THE NEXT 24 HOURS TO MORE UPPER SOUTHWEST FLOW OVER THE
WESTERN HALF OF THE REGION AND RIDGING ACROSS THE INTERIOR
NORTHWEST. BREEZY WINDS ACROSS THE EASTERN COLUMBIA RIVER GORGE
TODAY WILL DEVELOP EARLY AS WINDS AT DLS ARE ALREADY GUSTING TO
AROUND 15KTS OVERNIGHT. BY AFTERNOON SUSTAINED WINDS WILL REACH
AROUND 20 MPH WITH GUSTS TO AROUND 30 TO 35 MPH ACROSS THE
GORGE, OREGON COLUMBIA BASIN, CENTRAL OREGON AND THE KITTITAS
VALLEY. HEAT AND LOW RELATIVE HUMIDITY WILL BE THE MAIM IMPACTS
FROM THE DAILY STRONG SURFACE HEATING ACROSS THE LOWER
ELEVATIONS. HEATRISK WILL BE MAINLY IN THE MINOR CATEGORY
(YELLOW), BUT THE WARMEST DAY, THURSDAY, WILL BRING POCKETS OF
MORE ELEVATED HEAT RISK IN THE MODERATE CATEGORY, ACROSS THE
COLUMBIA BASIN, CENTRAL OREGON AND AND THE EASTERN BLUE
MOUNTAINS. MID LEVEL SHORTWAVE ENERGY AHEAD OF AN ADVANCING
COASTAL LOW ON FRIDAY INTO SATURDAY WILL DRIVE BREEZY TO WINDY
CONDITIONS AGAIN, WITH POTENTIAL TO ENHANCE FIRE WEATHER AND
STRONG WIND GUSTS THOUGH THE CASCADE GAPS EVEN DURING THE
OVERNIGHT HOURS. WINDS AT THIS TIME LOOK BELOW ADVISORY CRITERIA
AS NBM MEMBERS SUGGEST ONLY ABOUT 10- 20% CHANCES FOR SUSTAINED
WINDS EXCEEDING 39 MPH IN THE EASTERN COLUMBIA RIVER GORGE
SATURDAY.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
VFR CONDITIONS PREVAIL FOR ALL TAF SITES. ELEVATED SMOKE
PREVAILS WITH A SMALL CHANCE (5 TO 15 PERCENT CHANCE) THAT SOME
OF THE SMOKE WILL MAKE ITS WAY DOWN INTO THE SURFACE, BRINGING
TEMPORARY MVFR CONDITIONS. OTHERWISE, THE MAIN HIGHLIGHT WILL BE
BREEZY WINDS DEVELOPING THIS AFTERNOON IN DLS, RDM, AND BDN
THAT WILL MAINTAIN THROUGH MUCH OF THE AFTERNOON AND POSSIBLY
INTO THE EARLY EVENING HOURS.
FIRE WEATHER
A CROSS BARRIER PRESSURE GRADIENT WILL LEAD TO WESTERLY WINDS
THROUGH THE CASCADE GAPS TODAY. RED FLAG WARNINGS REMAIN IN
PLACE FOR THE LOWER COLUMBIA BASIN OF OREGON FROM LATE THIS
MORNING THROUGH 10 PM THIS EVENING FOR WIND AND LOW RELATIVE
HUMIDITY. EXPECT WINDS OF 15 TO 20 MPH WITH FREQUENT GUSTS IN
THE THE 25 TO 35 MPH RANGE, COUPLED WITH RELATIVE HUMIDITY IN
THE 15 TO 20 PERCENT RANGE. WEST NORTHWEST WINDS WITH GUSTS
PERSISTING THROUGH AROUND 9 PM ARE EXPECTED TO DIMINISH
TO AROUND 10 MPH BY LATE EVENING THROUGH HE OVERNIGHT.
PRELIMINARY POINT TEMPS/POPS
PDT 91 54 90 56 / 0 0 0 0
ALW 92 62 92 63 / 0 0 0 0
PSC 95 57 92 56 / 0 0 0 0
YKM 95 59 92 61 / 0 0 0 0
HRI 93 59 92 59 / 0 0 0 0
ELN 87 59 88 59 / 0 0 0 0
RDM 91 47 91 50 / 0 0 0 0
LGD 92 53 93 56 / 0 0 0 0
GCD 93 55 95 57 / 0 0 0 0
DLS 90 60 91 61 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...AIR QUALITY ALERT UNTIL 1 PM PDT WEDNESDAY FOR ORZ041-505-506-
509>511.
RED FLAG WARNING UNTIL 10 PM PDT THIS EVENING FOR ORZ691-701-
703.
DISCUSSION...71
AVIATION...95
FIRE WEATHER...71
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