181
FXUS66 KPDT 011700
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1000 AM PDT FRI MAY 1 2026
KEY MESSAGES
- MUCH ABOVE NORMAL TEMPERATURES THROUGH NEXT WEEK.
- LOW, MAINLY CASCADE SHOWER AND THUNDERSTORM CHANCES TODAY
THROUGH SUNDAY.
DISCUSSION
AN AREA OF HIGH PRESSURE WILL REMAIN OVER THE PACIFIC NORTHWEST
EARLY TODAY. HOWEVER, IT WILL BEGIN TO MOVE EASTWARD AS AN UPPER
TROUGH MOVES EASTWARD TOWARDS THE WASHINGTON AND OREGON COASTS.
THIS TROUGH WILL THEN DROP SOUTHWARD INTO SATURDAY AND
EVENTUALLY CLOSE OFF AN UPPER LOW. THE LOW WILL CONTINUE TO
MOVE SOUTH TO A POSITION OFF OF CALIFORNIA AND STRENGTHEN INTO
EARLY SUNDAY. BY LATER SUNDAY, THE LOW WILL MOVE ONSHORE IN
CENTRAL CALIFORNIA, THEN MOVE SOUTH AND EAST OVER THE SOUTHERN
GREAT BASIN.
BEHIND THIS LOW, STRONG HIGH PRESSURE WILL BUILD BACK IN TO THE
PACIFIC NORTHWEST.
HIGH TEMPERATURES WILL START OUT TODAY IN THE 70S TO LOWER 80S
ACROSS THE REGION. ON AVERAGE, THIS IS ABOUT 10 TO PERHAPS 15
DEGREES ABOVE NORMAL. BY MONDAY, HIGHS WILL BE MAINLY AT OR
ABOVE 80 DEGREES, WITH THE COLUMBIA BASIN AND YAKIMA VALLEY
CLOSE TO 90 DEGREES. THESE HIGH TEMPERATURES ON MONDAY WOULD BE
15 TO 20 DEGREES ABOVE NORMAL. SIMILAR TEMPERATURES ARE
EXPECTED TUESDAY AND WEDNESDAY. HIGHS SHOULD PEAK EARLY NEXT
WEEK, PROBABLY TUESDAY OR WEDNESDAY.
THERE IS SOME UNCERTAINTY IN THE GUIDANCE AS TO WHAT HAPPENS
AFTER MIDWEEK, BUT TEMPERATURES SHOULD AT LEAST COOL DOWN A
COUPLE OF DEGREES. IN THE MONDAY THROUGH WEDNESDAY TIME FRAME,
NBM PROBABILITIES OF HIGH TEMPERATURES >= 90 DEGREES REACH ABOUT
60 PERCENT ACROSS THE COLUMBIA BASIN AND YAKIMA VALLEYS. ECMWF
EFI FOR HIGH TEMPERATURES ANOMALIES ARE GENERALLY 0.8 TO 0.9
ACROSS THE COLUMBIA BASIN AND 0.7 TO 0.8 ACROSS A BROADER SWATH
OF THE REGION.
AS FAR AS SHOWER AND THUNDERSTORM CHANCES GO, THERE IS A
CHANCE OF SHOWERS (30 PERCENT) TODAY IN PORTIONS OF THE OREGON
CASCADES AND A SLIGHT CHANCE (20 PERCENT) IN THE WASHINGTON
CASCADES, BUT THUNDER POTENTIAL IS CONFINED TO THE OREGON
CASCADES AND PORTIONS OF CENTRAL OREGON (<15 PERCENT).
SATURDAY WILL SEE THE BEST POTENTIAL FOR RAIN AND THUNDER,
ALBEIT STILL LOW CHANCES WITH RAIN CHANCES AS HIGH AS 40 PERCENT
ACROSS PORTIONS OF THE OREGON CASCADES AND LOWER CHANCES ACROSS
SOME OF THE NEARBY HIGHLANDS. THUNDER POTENTIAL WILL STILL BE
MAINLY CONFINED TO THE OREGON CASCADES AND CENTRAL OREGON WITH
THUNDERSTORM POTENTIAL STILL 15 PERCENT OR LESS, THOUGH THE
AREAL COVERAGE COULD BE GREATER.
BY SUNDAY COVERAGE DECREASES AGAIN AND MAINLY CONFINED TO
PORTIONS OF CENTRAL OREGON AND THE CASCADES, WITH LESS
THUNDERSTORM COVERAGE AS WELL.
WITH THE LOW TAKING A FURTHER SOUTH TRACK THEN IT LOOKED LIKE A
FEW DAYS AGO, IT NOW LOOKS LIKE MONDAY ONWARD WILL BE DRY.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
VFR CONDITIONS WILL PERSIST THROUGH THE FORECAST PERIOD. WINDS
WILL BE GENERALLY LIGHT BELOW 10 KTS. CIGS HAVE BEGUN TO MOVE IN
OVERHEAD ALONG THE WESTER TAF SITES BUT WILL REMAIN 25KFT. 90
PRELIMINARY POINT TEMPS/POPS
PDT 51 82 51 83 / 0 0 0 0
ALW 55 82 56 83 / 0 0 0 0
PSC 51 87 52 89 / 0 0 0 0
YKM 55 84 54 87 / 0 0 0 0
HRI 50 85 52 87 / 0 0 0 0
ELN 51 80 50 82 / 0 10 0 0
RDM 44 78 44 81 / 10 10 10 0
LGD 46 77 47 79 / 0 0 0 10
GCD 48 78 47 80 / 0 0 0 10
DLS 56 85 57 89 / 10 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...77
AVIATION...90
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