852
FXUS66 KPDT 242234
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
334 PM PDT FRI APR 24 2026
KEY MESSAGES
- FRIGID MORNING TEMPERATURES SATURDAY
*FREEZE WARNINGS ISSUED*
- LIGHT MOUNTAIN SHOWERS SUNDAY AND MONDAY
- WARMING AND DRY THROUGH THE WEEK
DISCUSSION
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWS DRY CONDITIONS
UNDER MOSTLY CLEAR SKIES. THIS IS IN RESPONSE TO LOCAL HIGH
PRESSURE BEHIND THE COLD FRONT THAT HAS DROPPED SOUTH INTO
NORTHERN CALIFORNIA AND NEVADA, WHICH WILL KEEP SKIES CLEAR AND
FLOW ALOFT OUT OF THE NORTH. THESE CONDITIONS WILL ATTRIBUTE TO
RAPID COOLING AFTER SUNSET AS OVERNIGHT LOW TEMPERATURES MAY DROP
INTO THE LOW 30S ACROSS THE LOWER COLUMBIA BASIN, NORTHERN BLUE
MOUNTAIN FOOTHILLS, AND THE KITTITAS VALLEY. CONFIDENCE IS A BIT
LACKING AS TEMPERATURES WERE AROUND 5 DEGREES WARMER THAN
EXPECTED FRIDAY MORNING, AND THE NBMV5.0 SUGGESTS ONLY A 10%
CHANCE OF FREEZING TEMPERATURES OVER THE AFOREMENTIONED AREAS.
HOWEVER, THE NBMV4.3 ADVERTISES A 40-50% CHANCE OF SATURDAY
MORNING TEMPERATURES REACHING 32 DEGREES OR BELOW. EXPECTED
LIGHT, NORTH WINDS AND MOSTLY CLEAR SKIES DO SUPPORT
LOW TEMPERATURES NEAR FREEZING, BUT THE LIKELIHOOD OF VALUES
DIPPING MUCH FURTHER IS RATHER LOW. DUE TO THE POTENTIAL FOR
FREEZING MORNING TEMPERATURES, A FREEZE WARNING HAS BEEN ISSUED
ACROSS THE AFOREMENTIONED AREAS BETWEEN MIDNIGHT AND 8 AM
SATURDAY.
THE UPPER LEVEL TROUGH WILL CONTINUE TO DIG TO OUR SOUTHWEST
SATURDAY AS A REINFORCING SHORTWAVE SWINGS AROUND THE PARENT LOW
SUNDAY, WITH ANOTHER SHORTWAVE APPROACHING FROM THE NORTHWEST
ON MONDAY TO PROVIDE JUST ENOUGH MOISTURE TO BRING A RETURN TO
MOUNTAIN SHOWERS. BOTH THE ECWMF AI ENSEMBLES AND GFS ENSEMBLES
SHOWCASE PRECIPITABLE WATER AMOUNTS OF 0.25-0.40" BOTH SUNDAY
AND MONDAY, WHICH RELATE TO 65-85% OF NORMAL. THIS SUGGESTS
TRACE AMOUNTS OF SNOW AND RAINFALL ALONG THE CASCADE CREST
SUNDAY AND 0.03-0.07" ALONG THE CASCADE CREST, BLUE MOUNTAINS,
ELKHORNS, AND THE JOHN DAY HIGHLANDS MONDAY AS SNOW LEVELS
INCREASE FROM 4000-5000 FEET SUNDAY TO 5000-5500 FEET ON MONDAY.
CONFIDENCE IN THESE RAIN AMOUNTS IS MODERATE TO HIGH, WITH THE
NBM SHOWING A 30-40% CHANCE OF MEASURABLE RAINFALL (0.01" OR
GREATER) EXTENDING INTO THE BLUE MOUNTAIN FOOTHILLS AND A 10-20%
CHANCE REACHING LOWER ELEVATIONS OF THE KITTITAS, YAKIMA,
GORGE, AND LOWER COLUMBIA BASIN REGIONS.
GUIDANCE IS IN GOOD AGREEMENT WITH UPPER LEVEL RIDGING MOVING
ONSHORE AND SLOWLY PASSING THROUGH THE PACIFIC NORTHWEST THROUGH
THE REMAINDER OF THE WORKWEEK. THIS PATTERN IS EXPECTED TO KEEP
DRY CONDITIONS ACROSS THE AREA AS TEMPERATURES SLOWLY INCREASE
BEFORE PEAKING FRIDAY AND SATURDAY WITH HIGHS POTENTIALLY
REACHING INTO THE LOW 80S ACROSS THE LOWER COLUMBIA BASIN.
ENSEMBLE MEMBERS DO STRUGGLE WITH HOW IMPACTFUL AND EFFICIENT AN
INCOMING UPPER LEVEL SHORTWAVE WILL BE IN BREAKING DOWN THE
UPPER LEVEL RIDGE ON FRIDAY, DIRECTLY RELATING TO HIGHS MAKING
IT INTO THE LOW 80S BOTH DAYS. CURRENTLY, ONLY 35% OF MEMBERS
SHOW THE RIDGE WINNING THE BATTLE AND KEEPING BASIN TEMPERATURES
IN THE LOW 80S, WITH THE REMAINING MEMBERS SUGGESTING HIGHS IN
THE LOW TO MID-70S. HUMIDITIES WILL ALSO BE ON THE DOWNWARD
TREND AS AFTERNOON VALUES DIP INTO THE UPPER TEENS ACROSS
PORTIONS OF CENTRAL OREGON ON WEDNESDAY BEFORE EXPANDING INTO
THE HANFORD AREA THURSDAY AND THE JOHN DAY BASIN ON FRIDAY. THE
35% OF ENSEMBLES RELATED TO 80 DEGREE HIGH TEMPERATURES FRIDAY
ALSO ALIGN WITH AFTERNOON HUMIDITIES DIPPING INTO THE UPPER
TEENS ACROSS THE HANFORD AREA AND THROUGH CENTRAL OREGON.
HOWEVER, AN ADDITIONAL 27% OF MEMBERS, 52% IN TOTAL, ADVERTISE
AFTERNOON HUMIDITIES OF 25% OR BELOW. OVERNIGHT HUMIDITY
RECOVERIES ARE STILL EXPECTED TO BE MODERATE TO GOOD (50-70%)
OVER THESE AREAS ON FRIDAY, WHICH IS RELATED TO THE RELATIVE
ZONAL FLOW ON THURSDAY AND CLEAR SKIES OVERNIGHT ALLOWING
MORNING TEMPERATURES TO COOL TO 40-45 DEGREES. 75
AVIATION /00Z TAFS THROUGH 00Z SUNDAY/
VFR CONDITIONS TO
PREVAIL THROUGH THE PERIOD. WINDS WILL BE LIGHT WITH DIURNAL
WIND SHIFTS LATE THIS EVENING AND LATE TOMORROW MORNING. AN
OCCASIONAL GUST LESS THAN 20KTS MAY IMPACT SITES IN THE
AFTERNOON (CONFIDENCE 30-50%). LAWHORN/82
PRELIMINARY POINT TEMPS/POPS
PDT 32 59 34 60 / 0 0 0 0
ALW 36 59 38 61 / 0 0 0 10
PSC 34 64 35 67 / 0 0 0 0
YKM 35 63 36 65 / 0 0 0 0
HRI 32 63 34 65 / 0 0 0 0
ELN 32 58 34 60 / 0 0 0 10
RDM 24 57 27 57 / 0 0 0 0
LGD 29 55 30 56 / 0 10 0 20
GCD 27 56 29 56 / 0 10 0 10
DLS 38 66 39 67 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM PDT SATURDAY FOR
WAZ026-028-029.
OR...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 8 AM PDT SATURDAY FOR
ORZ044-507.
DISCUSSION...75
AVIATION...82
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