390
FXUS66 KPDT 181747
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1047 AM PDT WED MAR 18 2026
KEY MESSAGES
- UNSEASONABLY WARM TEMPERATURES THROUGH FRIDAY
- COOLER, MORE NORMAL TEMPERATURES BEYOND FRIDAY
- CONTINUED RAIN OVER THE WASHINGTON CASCADES WILL KEEP RIVERS
RUNNING HIGH.
DISCUSSION
A LARGE AREA OF HIGH PRESSURE OVER THE SOUTHWEST WILL CONTINUE
TO BUILD NORTHWARD THROUGH FRIDAY. THE BUILDING RIDGE WILL BRING
MAINLY DRY WEATHER AND TEMPERATURES THAT ARE 15 TO 20 DEGREES
ABOVE NORMAL TO THE PACIFIC NORTHWEST THROUGH FRIDAY. THE ONLY
EXCEPTION WILL BE FOR THE WASHINGTON CASCADES, WHICH WILL BE ON
THE NORTH SIDE OF THE RIDGE, WHICH WILL CONTINUE TO RECEIVE
RAIN.
BY LATER FRIDAY INTO SATURDAY, THE RIDGE IS PUSHED EASTWARD, A
COLD FRONT CROSSES THE REGION AND THE FLOW BECOMES MORE WESTERLY
AND ZONAL. THIS WILL ALLOW FOR A RETURN TO COOLER, MORE NORMAL
TEMPERATURES. WITH THE DRIER WESTERLY FLOW, THE CASCADES LOOK TO
DRY OUT THROUGH AT LEAST TUESDAY.
RAINFALL AMOUNTS OVER WASHINGTON CASCADES STILL LOOK TO BE CLOSE
TO 2 INCHES ALONG THE CREST, WITH LESSER AMOUNT ELSEWHERE. QPF
DID COME DOWN A BIT WITH THIS RUN. AMOUNTS ON THE OREGON
CASCADES AND BLUE MOUNTAINS ARE GENERALLY 0.25 INCHES OR LESS.
THE AMOUNTS ACROSS THE WASHINGTON CASCADES, ALONG WITH THE MUCH
WARMER TEMPERATURES CAUSING SNOW MELT WILL CONTRIBUTE TO HIGH
RIVERS. SOME RIVERS, MAINLY THE NACHES AND AND YAKIMA WILL HAVE
POINTS THAT APPROACH OR EXCEED FLOOD STAGE.
HIGH TEMPERATURES IN THE LOWER ELEVATIONS AND CENTRAL OREGON
WILL BE IN THE LOWER TO MID 70S THROUGH FRIDAY AND COULD
APPROACH 80 DEGREES IN CENTRAL OREGON. THESE VALUES WOULD BE 15
TO 20 DEGREES ABOVE NORMAL, AND WOULD BE CLOSE TO RECORDS IN
MANY AREAS. OVERNIGHT LOWS WILL MAINLY BE IN THE 40S, BUT MAY
NOT DROP BELOW 50 IN THE COLUMBIA BASIN AND ALONG THE FOOTHILLS
OF THE BLUE MOUNTAINS.
THE ECMWF EFI SHOWS WIDESPREAD VALUES OF 1.00 FOR HIGH
TEMPERATURES ACROSS EASTERN AND CENTRAL OREGON AND 0.8 TO 0.9
ACROSS SOUTHEASTERN WASHINGTON. FOR LOWS, VALUES GENERALLY RANGE
FROM 0.8 TO 0.95. NBM PROBABILITIES OF HIGH TEMPERATURES >= 80
DEGREES ARE AROUND 90 PERCENT IN CENTRAL OREGON AND 30 TO 40
PERCENT IN THE COLUMBIA BASIN AND FOOTHILLS OF THE BLUE
MOUNTAINS.
ADDITIONALLY, THERE WILL BE SOME DIURNALLY BREEZY WINDS TODAY,
THURSDAY, AND ESPECIALLY FRIDAY AS THE COLD FRONT MOVES
THROUGH. WINDS WILL BE STRONGEST IN THE SIMCOE HIGHLANDS AND
CASCADE GAPS AS WELL AS THE COLUMBIA BASIN. WIND GUSTS WILL
MAINLY BE IN THE 20 TO 30 MPH RANGE TODAY AND THURSDAY, THOUGH
POSSIBLY A BIT HIGHER IN THE SIMCOE HIGHLANDS AND 25 TO 35 MPH
RANGE ON FRIDAY.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
VFR CONDITIONS PREVAIL WITH LIGHT WINDS LESS THAN 15 KNOTS. BDN
IS THE ONLY EXCEPTION WITH 20 TO 30 MPH GUSTS THAT WILL LINGER
THROUGH THE AFTERNOON HOURS. OTHERWISE, HIGH CIGS AND
VISIBILITIES WILL PERSIST.
PRELIMINARY POINT TEMPS/POPS
PDT 73 47 73 50 / 0 0 0 0
ALW 72 52 72 53 / 0 0 0 10
PSC 74 49 73 51 / 0 0 0 0
YKM 70 46 69 46 / 10 10 10 10
HRI 74 47 74 50 / 0 0 0 0
ELN 61 42 61 44 / 30 20 30 30
RDM 78 41 77 43 / 0 0 0 0
LGD 75 46 74 48 / 0 0 0 0
GCD 77 44 74 48 / 0 0 0 0
DLS 71 47 69 50 / 0 0 10 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...77
AVIATION...95
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