604
FXUS66 KPDT 170513
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1013 PM PDT SUN AUG 16 2026
KEY MESSAGES
- SOUTHWEST FLOW THROUGH MONDAY WILL BRING SHOWER AND ISOLATED
THUNDERSTORM CHANCES MAINLY TO FAR EASTERN OREGON.
- INCREASED GAP WIND POTENTIAL MONDAY NIGHT INTO TUESDAY.
- ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS TOWARD THE
WEEKEND.
DISCUSSION
SOUTHWEST FLOW WILL CONTINUE THROUGH MONDAY. SEVERAL SHORT
WAVES WILL MOVE THROUGH THE FLOW. THESE SHORT WAVES COUPLED
WITH RESIDUAL MOISTURE COULD TRIGGER SHOWERS AND ISOLATED
AFTERNOON THUNDERSTORMS, MAINLY FOR WALLOWA COUNTY, BUT OTHER
MOUNTAIN AREAS CAN'T BE RULED OUT.
BY TUESDAY, THE PACIFIC NORTHWEST GETS INTO MORE OF A SPLIT FLOW
PATTERN AND AS A RESULT, WEST WINDS WILL INCREASE ACROSS THE
AREA. WINDS WILL BECOME GUSTY BEGINNING MONDAY NIGHT AND INTO
TUESDAY, WITH WIND GUSTS 20 TO 30 MPH, WITH SOME LOCATIONS
POSSIBLY AS HIGH AS 35 MPH, IN THE USUALLY BREEZIER AREAS SUCH
AS THE KITTITAS VALLEY, SIMCOE HIGHLANDS, BLUE MOUNTAIN
FOOTHILLS, COLUMBIA BASIN AND GORGE. NBM PROBABILITIES OF WIND
GUSTS >=25 MPH ARE >60 PERCENT, WHILE NBM PROBABILITIES OF WIND
GUSTS >= 39 MPH ARE GENERALLY 50 PERCENT OR LESS.
RH VALUES DO DECREASE A BIT BETWEEN MONDAY AND TUESDAY AND WITH
THE GUSTY WINDS, FIRE WEATHER CONDITIONS WILL BE ELEVATED, AND
COULD BECOME CRITICAL. TUESDAY WILL HAVE TO BE MONITORED FOR ANY
FIRE WEATHER HEADLINES.
BEYOND TUESDAY, THE MIDWEEK PERIOD LOOKS RATHER QUIET, IN DRY
WEST TO SOUTHWEST FLOW.
HOWEVER, BY THE WEEKEND AN AREA OF LOW PRESSURE WILL MOVE
NORTHWARD OFF THE COAST. THIS LOW IS THEN EXPECTED TO MOVE
ONSHORE IN OREGON OR WASHINGTON AT SOME POINT ON SATURDAY. THERE
IS STILL SOME DISAGREEMENT AS TO WHERE THE LOW COMES ASHORE AND
HOW STRONG IT WILL BE AND THE NATURAL UNCERTAINTY IN A FORECAST
5 DAYS OUT, BUT SHOWER AND THUNDERSTORM CHANCES DO LOOK TO
INCREASE, ESPECIALLY FOR THE MOUNTAINS AS WE HEAD INTO THE
WEEKEND.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
VFR CONDITIONS ARE FORECAST AT ALL SITES THROUGH THE PERIOD,
EXCEPT FOR TEMPORARY MVFR DUE TO A LAYER OF SMOKE PRESENTING A
CEILING AT BDN LATE THIS EVENING. OTHERWISE, THERE IS LOW
CONFIDENCE (20%) IN ANY SMOKE IMPACTS REDEVELOPING AT SITES,
THOUGH IF IMPACTS DO OCCUR EXPECT REDUCTION IN VSBY IN THE
OVERNIGHT AND EARLY MORNING HOURS. WINDS WILL BE PREDOMINANTLY
LIGHT AT 10 KTS OR LESS, EXCEPT AT DLS WHERE BREEZY WESTERLY
WINDS ARE FORECAST DURING THE LATE AFTERNOON AND EVENING HOURS
ON MONDAY. SKIES WILL CONSIST OF SCT-BKN MID/HIGH CLOUD FOR THE
MAJORITY OF THE PERIOD.
FIRE WEATHER
ISOLATED SHOWERS AND THUNDERSTORMS (<20% MONDAY) ARE POSSIBLE
MAINLY ACROSS WALLOWA COUNTY IN SOUTHWEST FLOW.
AS THE FLOW BECOMES MORE WESTERLY MONDAY NIGHT INTO TUESDAY,
WINDS WILL INCREASE AND BECOME GUSTY, WITH GUSTS AS HIGH AS 20
TO 30 MPH AND POSSIBLY AS HIGH AS 35 MPH ACROSS THE KITTITAS
VALLEY, SIMCOE HIGHLANDS, BLUE MOUNTAIN FOOTHILLS AND THE
COLUMBIA BASIN AND GORGE. THESE WINDS AND LOW RELATIVE
HUMIDITIES WILL YIELD ELEVATED FIRE WEATHER CONDITIONS TUESDAY
AND COULD BRING CRITICAL CONDITIONS ONCE AGAIN.
BEYOND THAT, THERE IS THE POTENTIAL FOR MORE THUNDERSTORMS GOING
INTO NEXT WEEKEND.
PRELIMINARY POINT TEMPS/POPS
PDT 88 57 89 58 / 0 0 0 0
ALW 92 63 91 64 / 0 0 0 0
PSC 91 59 94 60 / 0 0 0 0
YKM 91 60 94 61 / 0 0 0 0
HRI 92 61 92 63 / 0 0 0 0
ELN 87 58 90 60 / 0 0 0 0
RDM 87 51 88 49 / 0 0 0 0
LGD 86 57 92 57 / 10 10 20 20
GCD 91 56 92 56 / 0 0 10 10
DLS 87 60 93 62 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...AIR QUALITY ALERT UNTIL NOON PDT MONDAY FOR WAZ026-522-523.
OR...AIR QUALITY ALERT UNTIL NOON PDT MONDAY FOR ORZ041-503-505-506-
508>511.
DISCUSSION...77
AVIATION...86
FIRE WEATHER...77
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