715
FXUS66 KPDT 200505
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1005 PM PDT THU MAR 19 2026
KEY MESSAGES
- MOUNTAIN RAIN WILL PERSIST THROUGH FRIDAY BEFORE
TRANSITIONING TO SNOW
- ABOVE SEASONAL AVERAGE TEMPERATURES REMAIN THROUGH FRIDAY
- A SYSTEM WILL BRING TEMPERATURES BACK TO SEASONAL AVERAGE
SATURDAY
DISCUSSION
A STALLED 500 TO 700 KG/MS MAGNITUDE ATMOSPHERIC RIVER
CONTINUES WITH OROGRAPHIC LIFT CREATING PERSISTENT RAIN ACROSS
THE WASHINGTON CASCADE CREST FOR THE NEXT COUPLE OF DAYS. HIGH
SNOW LEVELS BETWEEN 7 AND 9K FT AGL WILL LEAD TO AT LEAST
ANOTHER ONE TO TWO INCHES OF RAINFALL FROM SNOQUALMIE PASS AND
AREAS NORTH. WITH THE LARGE WESTERN CONUS HIGH PRESSURE, EXPECT
ONE MORE DAY OF THE ANOMALOUSLY WARM TEMPERATURES. THE WEATHER
IN CONTEXT TOOL FLAGS FRIDAY AS A POTENTIALLY RECORD BREAKING
TEMPS AT PDT IF THE TEMPS HITS 79F. LIKEWISE OVERNIGHT LOWS IN
THE HIGH 40S HAVE POTENTIAL FOR RECORD TIES OR BREAKING. PSC
COULD TIE AT 75F AND BREAK IF THE LOW IS 52F. ESAT AND SHIFT OF
TAILS CONTINUES TO SHOW EXTREMELY HIGH CONFIDENCE FOR A RARE
EPISODE, WITH BOTH TODAY AND FRIDAY ACROSS MOST FOR OREGON AND
INTO SOUTH EAST WASHINGTON. BEND HIT 81 DEGREES YESTERDAY, AND
THE BROADER AREA HAD LOW TO UPPER 70S DEPENDING GENERALLY ON
ELEVATION. THE SAME WARM PATTERN EXISTS WITH POTENTIAL FOR
AROUND 80 DEGREES ACROSS THE JOHN DAY BASIN AND CENTRAL OREGON
THROUGH FRIDAY. THE COLD FRONT THAT HAS BEEN ANTICIPATED FOR
THE FRIDAY NIGHT TIME FRAME LOOKS TO BECOME BEST SIGNALED FOR
FROPA AS THE NAM 1000-500 MB HEIGHTS FALL FROM AROUND 557DM
FRIDAY EVENING TO 540DM BY 12Z SATURDAY. THIS WILL ALSO SIGNAL
THE BREAK IN THE AR MOISTURE STREAM IN WA, FAVORING SHOWERS
ACROSS THE BLUES THROUGH SATURDAY. SATURDAY WILL BE THEN START
OF A DRY PERIOD THAT WILL RUN THROUGH ABOUT MONDAY NIGHT WHEN
MOUNTAIN SHOWERS COULD RETURN (30-50% CHANCES) ACROSS THE
WASHINGTON CASCADES. SNOW LEVELS AVERAGING AROUND 4-5K FT AGL
WILL TRANSLATE IN THE -RA/SN MIXED OVER THE UPPER SLOPES AND
RAIN ONLY ACROSS THE LOWER SLOPES. THESE SLS CRASHING DOWN
BELOW 4000 FT BY WEDNESDAY, WHERE AN ALL SNOW PRECIP TYPE WOULD
BE FIRMLY ESTABLISHED ACROSS THE CASCADE CREST IN BOTH WA AND
OR. RUSSELL/71
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
VFR CONDITIONS WILL PREVAIL ACROSS ALL SITES THROUGH FRIDAY.
WINDS GENERALLY 10 KTS OR LESS OVERNIGHT, THEN BECOMING GUSTY IN
THE 20 TO 25 KT RANGE FRIDAY AFTERNOON. WINDS SHOULD DECREASE
AGAIN FRIDAY EVENING.
FIRE WEATHER
AREAS OF CENTRAL OREGON INTO THE JOHN DAY/OCHOCO HIGHLANDS ARE
HIGHLIGHTED WITH AN ELEVATED FIRE WEATHER RISK FOR THE BALANCE
OF THIS AFTERNOON, OWING TO LOW RELATIVE HUMIDITY AND WIND GUSTS
THAT ARE EXPECTED TO CONTINUE ABOVE 20 MPH DURING THE
AFTERNOON. THE LOW RELATIVE HUMIDITY AND GENERALLY GUSTY SURFACE
WINDS WILL STILL PROMOTE RAPID FIRE SPREAD FOR ANY DRY GRASSES
ACROSS THE CENTRAL OREGON AND JOHN DAY/OCHOCO HIGHLANDS ON
FRIDAY AFTERNOON AS WELL. A COLD FRONT OVERNIGHT FRIDAY NIGHT
INTO SATURDAY MORNING WILL ALLOW RECOVERY OF THE LOW RH VALUES
THROUGH COOLER AIR GETTING INTO THE LOCAL AREA. RUSSELL/71
HYDROLOGY
THE NACHES RIVER AT NACHES, AND THE REACH UP AND DOWNSTREAM WILL
BE PRONE TO EXCEEDING THE BANK OVER THE WEEKEND. THE NACHES
RIVER AT NACHES IS UNDER A FLOOD WARNING AND HAS A 99 PERCENT
CHANCE OF BEING ABOVE MINOR FLOOD STAGE AT LEAST THROUGH
SATURDAY. THE KIONA FORECAST POINT ON THE YAKIMA RIVER HAS A 24%
CHANCE OF REACHING FLOOD STAGE BASED ON HEFS (ENSEMBLES) BY
MIDDAY SUNDAY. RUSSELL/71
PRELIMINARY POINT TEMPS/POPS
PDT 48 74 46 58 / 10 10 30 40
ALW 54 74 48 59 / 10 10 40 50
PSC 52 77 49 64 / 20 10 20 20
YKM 49 71 42 58 / 20 30 10 0
HRI 49 76 48 62 / 10 10 20 20
ELN 46 61 39 50 / 40 50 20 10
RDM 44 76 42 57 / 0 0 0 10
LGD 48 77 45 56 / 0 0 30 60
GCD 48 78 46 57 / 0 0 10 50
DLS 50 70 47 59 / 10 20 30 20
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...71
AVIATION...77
FIRE WEATHER...90
HYDROLOGY...83
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