086
FXUS66 KPDT 052118
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
218 PM PDT SAT SEP 5 2026
KEY MESSAGES
- AN UPPER LOW WILL BRING PERIODS OF SHOWERS THIS WEEKEND,
MAINLY OVER THE MOUNTAINS...WITH THE BEST CHANCES SUNDAY INTO
MONDAY.
- ISOLATED THUNDERSTORMS CHANCES (<25%) ACROSS THE MOUNTAINS
THROUGH MONDAY.
- DRIER CONDITIONS FROM LATER MONDAY ONWARD.
DISCUSSION
AN UPPER LOW OVER THE PACIFIC NORTHWEST WILL SLOWLY MOVE
EASTWARD THROUGH SUNDAY AND BY MONDAY WILL GENERALLY BE EAST OF
THE AREA. THE ASSOCIATED TROUGH WILL GRADUALLY FLATTEN AND BY
LATER MONDAY, THE FLOW WILL BECOME SPLIT ACROSS THE REGION.
RIDGING FROM THE SOUTH WILL BUILD IN BY MIDWEEK, BEFORE ANOTHER
TROUGH DROPS DOWN FOR NEXT WEEKEND.
THE PERSISTENT UPPER LOW WILL CONTINUE TO BRING UNSETTLED
WEATHER OVER THE REGION, WITH PERIODS OF SHWOERS, MAINLY OVER
THE MOUNTAINS. THE BEST TIME FOR MORE WIDESPREAD SHOWERS LOOKS
TO BE SUNDAY AFTERNOON/EVENING INTO EARLY MONDAY MORNING.
THERE WILL ALSO BE CHANCES FOR ISOLATED AFTERNOON AND EVENING
THUNDERSTORMS MAINLY DURING THE AFTERNOON AND EVENINGS,
ESPECIALLY OVER THE MOUNTAINS. BY MONDAY AFTERNOON,
PRECIPITATION CHANCES SHIFT GENERALLY FROM THE BLUE MOUNTAINS
EASTWARD, AND BY LATER MONDAY GENERALLY EAST OF THE AREA.
QPF VALUES HAVE DECREASE A BIT EVERYWHERE EXCEPT ALONG THE
OREGON CASCADE CREST THIS AFTERNOON/EVENING, WHERE AMOUNTS ARE
GENERALLY >0.50 INCHES. ELSEWHERE AMOUNTS ARE GENERALLY LESS
THAN 0.25 INCHES. ON SUNDAY INTO MONDAY, AMOUNTS ARE HIGHEST
OVER THE BLUE MOUNTAINS AND PINTS EASTWARD WHERE AMOUNTS RANGE
FROM 0.25 TO 0.50 INCHES.
TEMPERATURES REMAIN 10 TO 15 DEGREES BELOW NORMAL THROUGH THE
WEEKEND AND THE ECMWF EFI PUTS MUCH OF THE AREA IN THE 0.7 TO
0.8 BELOW NORMAL. ON SUNDAY, MUCH OF THE SOUTHERN OREGON BLUE
MOUNTAINS AND PORTIONS OF CENTRAL OREGON ARE IN THE 80TH TO
90TH PERCENTILE FOR PRECIPITATION AS WELL, FROM THE EFI.
MONDAY LOOKS TO BE A BIT BREEZY WITH WINDS 25 TO 30 MPH,
POSSIBLY AS HIGH AS 35 MPH IN THE CASCADE GAPS, COLUMBIA BASIN,
GORGE, SIMCOE HIGHLANDS AND KITTITAS VALLEY.
BEYOND MONDAY, DRY WEATHER WILL MOVE IN AS THE TROUGH MOVES EAST
OF THE REGION AND THE FLOW BECOMES MORE SPLIT AND ZONAL. BY
MIDWEEK, THERE WILL BE SOME RIDGING MOVING IN FROM THE SOUTH.
MOST OF THE WEEK LOOKS DRY WITH MORE SEASONABLE TEMPERATURES.
ANOTHER TROUGH LOOKS TO APPROACH TOWARD THE END OF THE WEEK AND
WILL BRING PRECIPITATION CHANCES AGAIN, MAINLY TO THE MOUNTAINS.
THIS TROUGH LOOKS TO BE PROGRESSIVE AND MOVES THROUGH RATHER
THAN LINGERING IN PLACE.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
SHOWERS CONTINUE TO PREVAIL THROUGH THE FORECAST AREA THROUGH
TOMORROW WITH ON AND OFF CHANCES THROUGH THE PERIOD. WILL SEE
GREATER CHANCES OF PRECIP ALONG THE CENTRAL OREGON SITES IN THE
LATER AFTERNOON TO EVENING HOURS TONIGHT. CURRENTLY DON'T HAVE
MVFR OR LOWER AS CONFIDENCE IS LOWER IN THIS SET-UP. THERE'S A 5
TO 15 PERCENT CHANCE WE CAN SEE MODERATE SHOWERS MOVING OVER
SOME OF THE TAF SITES, REDUCING VISIBILITY AND/OR CLOUD DECKS
DOWN TO AT LEAST MVFR LEVELS.
PRELIMINARY POINT TEMPS/POPS
PDT 70 45 68 48 / 30 10 30 40
ALW 72 50 71 52 / 30 10 10 60
PSC 75 48 73 50 / 20 0 20 30
YKM 72 51 72 52 / 40 10 30 10
HRI 73 49 71 50 / 20 10 30 30
ELN 69 45 71 48 / 50 10 20 20
RDM 67 40 61 37 / 20 60 90 50
LGD 72 43 72 46 / 30 10 50 80
GCD 70 45 69 46 / 40 10 70 80
DLS 74 55 71 55 / 30 30 50 10
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...77
AVIATION...95
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