888
FXUS66 KPDT 042323
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
423 PM PDT SAT OCT 4 2025
UPDATED AVIATION DISCUSSION
AVIATION...00Z TAFS
VFR CONDITIONS PREVAIL THROUGHOUT THIS
PERIOD. KDLS/KYKM WILL HAVE BREEZY WINDS AT 15-25KTS THROUGH THIS
EVENING AS THE SURFACE PRESSURE GRADIENTS STRENGTHEN. THE REMAINING
SITES WILL HAVE LESS THAN 12KTS. KRDM MAY SEE WINDS BECOME BREEZY
TOMORROW AFTERNOON, BUT WITH A LOW CHANCE (15-30%). FEASTER/97
PREV DISCUSSION
/ISSUED 122 PM PDT SAT OCT 4 2025/
DISCUSSION
KEY MESSAGES:
1. LIGHT MOUNTAIN SHOWERS POSSIBLE TODAY.
2. COLD MORNING TEMPERATURES THROUGH TUESDAY.
*FREEZE WATCH ISSUED*
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWS LIGHT RETURNS
BEGINNING TO DEVELOP ALONG THE CASCADE CREST AND EAST SLOPES OF
THE WASHINGTON CASCADES UNDER PARTLY TO MOSTLY CLOUDY SKIES. THESE
CONDITIONS ARE IN RESPONSE TO A WEAK UPPER LEVEL TROUGH AND
ASSOCIATED COLD FRONT THAT WILL BE PASSING THROUGH THE AREA FROM
THE NORTHWEST TODAY, BRINGING LIGHT RAIN TO HIGHER ELEVATIONS OF
THE CASCADES, BLUE MOUNTAINS, AND JOHN DAY HIGHLANDS THIS
AFTERNOON AND EVENING. RAIN AMOUNTS OF 0.04" OR LESS ARE EXPECTED
OVER THE AFOREMENTIONED AREAS, BUT HIGHER ELEVATIONS IN WALLOWA
COUNTY MAY SEE AMOUNTS NEAR A WETTING RAIN (0.10"). CONFIDENCE IN
THESE RAIN AMOUNTS IS HIGH AS THE HREF SUGGESTS A 30-50% CHANCE
OF 0.02" OR GREATER RAINFALL AMOUNTS AND A 20-40% CHANCE OF 0.04"
OR GREATER RAINFALL AMOUNTS OVER THE AFOREMENTIONED AREAS. DUE TO
THE DROPPING SYSTEM, SNOW LEVELS WILL DECREASE TO AROUND 6000
FEET, SO HIGHER ELEVATIONS OF THE ELKHORNS MAY RECEIVED UP TO AN
INCH OF SNOWFALL TONIGHT INTO EARLY SUNDAY MORNING.
FLOW ALOFT WILL BECOME MORE FROM THE NORTH TONIGHT IN THE WAKE OF
THE PASSING SYSTEM, PROMOTING THE ENCROACHMENT OF A COLDER AND
DRIER AIRMASS INTO THE AREA. HIGH TEMPERATURES WILL COOL 3-5
DEGREES FROM TODAY TO SUNDAY, WITH MONDAY MORNING TEMPERATURES
DROPPING ABOUT 10 DEGREES FROM SUNDAY MORNING AS EFFICIENT
RADIATIONAL COOLING ENHANCES OVERNIGHT COOLING SUNDAY NIGHT. LOW
TEMPERATURES MONDAY WILL BE DIPPING INTO THE MID-TO UPPER 20S
ACROSS AREAS OF CENTRAL OREGON, GRANDE RONDE VALLEY, AND WALLOWA
COUNTY, WHICH HAS PROMPTED THE ISSUANCE OF A FREEZE WATCH SUNDAY
NIGHT THROUGH MONDAY MORNING. CONFIDENCE IN THESE TEMPERATURES
DROPPING BELOW IS MODERATE TO HIGH (60-90%) VIA THE NBM. CHILLY
MORNING TEMPERATURES WILL ALSO EXTEND ACROSS THE COLUMBIA BASIN,
BLUE MOUNTAIN FOOTHILLS, AND THE YAKIMA/KITTITAS VALLEYS, AS LOW
TEMPERATURES IN THE MID-TO UPPER 30S ARE EXPECTED.
DETERMINISTIC AND ENSEMBLE GUIDANCE IS IN GOOD AGREEMENT WITH THE
UPPER LEVEL FLOW SHIFTING FROM THE NORTH TO THE WEST MONDAY NIGHT
INTO TUESDAY MORNING, ALLOWING WARMER TEMPERATURES TO GRACE THE
AREA. HOWEVER, GUIDANCE STRUGGLES WITH THE OVERALL PATTERN TUESDAY
ONWARD IN RELATION TO THE STRENGTH, LOCATION, AND PROGRESSION OF
AN INCOMING UPPER LEVEL LOW PRESSURE SYSTEM MID-TO LATE WEEK.
CURRENT CONSENSUS OF 63% OF ENSEMBLE MEMBERS KEEP THE LOW OFFSHORE
UNTIL THE WEEKEND, WHICH WOULD KEEP TEMPERATURES NEAR NORMAL AND
CONDITIONS RATHER DRY AS AFTERNOON HUMIDITIES HOVER BETWEEN
20-40%. THE NEXT CHANCE OF SHOWERS, CONFINED TO HIGHER TERRAIN OF
THE BLUE MOUNTAINS, WILL BE ON THURSDAY. AT THIS TIME, CONFIDENCE
IS LOW (20-30%), AS ENSEMBLE MEMBERS ARE SPLIT (51%/49%) IN
REGARDS TO THE UPPER LEVEL LOW'S PROXIMITY TO THE COAST - DIRECTLY
RELATED TO HOW EFFICIENT MOISTURE TRANSPORT WILL BE EAST OF THE
CASCADES. THERE ARE BETTER CHANCES (40-50%) OF RAIN SHOWERS
SATURDAY AFTERNOON AND SUNDAY, BUT STILL LOW CONFIDENCE (20%) IN
TIMING AND RAIN AMOUNTS THIS FAR FROM THE EVENT. 75
PRELIMINARY POINT TEMPS/POPS
PDT 42 64 38 67 / 10 0 0 0
ALW 43 64 41 68 / 20 0 0 0
PSC 43 68 35 69 / 10 0 0 0
YKM 43 67 39 69 / 0 0 0 0
HRI 45 68 36 69 / 10 0 0 0
ELN 38 65 34 67 / 0 0 0 0
RDM 34 62 27 67 / 0 0 0 0
LGD 39 63 33 67 / 20 0 0 0
GCD 38 63 32 68 / 10 0 0 0
DLS 49 71 43 72 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
OR...FREEZE WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY MORNING FOR
ORZ049-050-505-511.
WA...NONE.
SHORT TERM...75
LONG TERM....75
AVIATION...97
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