004
FXUS66 KPDT 022026
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
126 PM PDT THU OCT 2 2025
DISCUSSION
KEY MESSAGES:
1. PERIODS OF SHOWERS AND ISOLATED THUNDERSTORMS TODAY.
2. COOLER CONDITIONS THROUGH THE WEEKEND.
3. COLD MORNING TEMPERATURES SUNDAY THROUGH TUESDAY.
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWING SPOTTY, LIGHT
RETURNS ALONG THE BLUE MOUNTAINS AND THE EAST SLOPES OF THE
CASCADES UNDER MOSTLY CLOUDY SKIES. THIS IS IN RESPONSE TO AN
UPPER LEVEL TROUGH AND ASSOCIATED COLD FRONT STALLING ALONG THE
COAST. THE DEEPENING OFFSHORE TROUGH AND EROSION OF THE RIDGE TO
OUR EAST WILL PROMOTE THE POTENTIAL FOR ISOLATED AFTERNOON
THUNDERSTORMS ACROSS AREAS OF CENTRAL OREGON AND THE BLUE
MOUNTAINS/FOOTHILLS. THE HREF ADVERTISES 100-200 J/KG OF SURFACE
CAPE, LOW LEVEL SHEAR OF 50-55KTS, AND LAPSE RATES OF AROUND 6/KM.
THESE PARAMETERS DO SUGGEST THE POTENTIAL FOR ISOLATED, DISCRETE
STORM CELLS TO FORM, BUT SHOULD STAY BRIEF AND SUB-SEVERE (<10% OF
SEVERE STORMS).
RAIN CHANCES WILL WILL PEAK BETWEEN 2 PM AND 7 PM TODAY BEFORE
TAPERING OFF OVER THE BLUE MOUNTAINS AND FOOTHILLS UNTIL CLOSER TO
11 PM. MINIMAL RAIN AMOUNTS ARE EXPECTED, WITH HIGHEST
ACCUMULATIONS ACROSS THE SOUTHERN BLUE MOUNTAINS, JOHN DAY
HIGHLANDS, AND THE EAST SLOPES OF THE OREGON CASCADES WITH AMOUNTS
BETWEEN 0.10-0.20" LIKELY. THERE COULD BE AREAS OF SLIGHT HIGHER
AMOUNTS NEARING 0.20-0.30" AT HIGHER ELEVATIONS AND NEAR
DEVELOPING THUNDERSTORM CELLS, BUT CHANCES ARE RELATIVELY LOW
(30-40%) VIA THE NBM. THE BLUE MOUNTAIN FOOTHILLS, NORTH-CENTRAL
OREGON, JOHN DAY BASIN, AND WALLOWA/UNION COUNTIES ARE EXPECTED TO
RECEIVE 0.02-0.10", WITH LESS THAN 0.02" EXPECTED ACROSS THE LOWER
COLUMBIA BASIN AND CONDITIONS STAYING DRY OVER THE YAKIMA/KITTITAS
VALLEYS.
THE UPPER LEVEL TROUGH OFFSHORE DIGS SOUTH TONIGHT AND MOVES
ONSHORE OVER NORTHERN CALIFORNIA FRIDAY MORNING BEFORE PROGRESSING
INTO THE LAS VEGAS AREA BY FRIDAY EVENING. A BRIEF TRANSIENT RIDGE
WILL FOLLOW IN THE DROPPING SYSTEM'S WAKE ON FRIDAY, BRINGING WITH
IT DRIER CONDITIONS THROUGH THE MAJORITY OF THE DAY. AN SECOND
UPPER LEVEL TROUGH WILL DROP THROUGH BRITISH COLUMBIA AND INTO
NORTHEASTERN WASHINGTON SATURDAY, BRINGING A RETURN TO LIGHT RAIN
CHANCES (20-30%) ACROSS THE CASCADES AND BLUE MOUNTAINS DURING THE
MORNING AND AFTERNOON. MINIMAL RAIN AMOUNTS ARE EXPECTED OF 0.03"
OR LESS ACROSS MOUNTAINOUS TERRAIN OF THE BLUE AND CASCADE
MOUNTAINS, WITH THE NBM SUGGESTING A 40-50% OF 0.02" OR MORE RAIN
OVER THE AFOREMENTIONED AREAS SATURDAY.
NORTHWEST FLOW WILL INITIATE FRIDAY AND EXTEND INTO EARLY NEXT
WEEK, KEEPING TEMPERATURES BELOW NORMAL AND DROPPING LOW
TEMPERATURES INTO THE UPPER 20S ACROSS LOWER ELEVATIONS OF CENTRAL
OREGON AS UPPER LEVEL FLOW BECOMES MORE NORTHERLY. ENSEMBLES ARE
CURRENTLY LOOKING MORE FAVORABLE FOR LOW TEMPERATURES TO BUMP UP
SLIGHTLY BOTH SUNDAY AND MONDAY MORNINGS WITH 52% OF MEMBERS ON
SUNDAY AND 80% OF MEMBERS ON MONDAY RELATED TO MORE OF A MARINE
INFLUENCE SLOWING OVERNIGHT COOLING. AT THIS TIME, THERE IS A
30-50% CHANCE OF FREEZING TEMPERATURES FOR REDMOND, BEND, AND LA
GRANDE SUNDAY MORNING, A 50-80% CHANCE ON MONDAY MORNING, AND A
30-60% CHANCE ON TUESDAY MORNING.
ENSEMBLES STRUGGLE WITH THE OVERALL PATTERN TUESDAY ONWARD AS
MEMBERS SUGGEST A RIDGE OFFSHORE AND A DROPPING SYSTEM MIDWEEK. AT
THIS TIME, THE LEADING SCENARIO (50-60%) IS ANOTHER DROPPING
SYSTEM OFFSHORE THURSDAY, BRINGING A RETURN TO WIDESPREAD LIGHT
RAIN CHANCES TO THE AREA. 75
AVIATION...18Z TAFS
VFR CONDITIONS CURRENTLY ACROSS ALL SITES,
BUT MOST TERMINALS ARE EXPECTED TO ENCOUNTER BRIEF TIMES OF MVFR
THIS AFTERNOON DUE TO SHOWERS AND ISOLATED THUNDERSTORM POTENTIAL
IN THE AREA. BEST CHANCES (15-25%) FOR THUNDERSTORMS WILL OCCUR
FOR KBDN, WHICH MAY DEGRADE VISIBILITY TO 4SM AND CEILINGS TO
25-29KFT. ELSEWHERE, BRIEF MVFR CONDITIONS WILL RESULT IN REDUCED
CEILINGS OF 25-29KFT. WINDS ARE EXPECTED TO BE LIGHT AND BELOW 7
KTS, WITH THE EXCEPTION OF GUSTY AND ERRATIC WINDS NEAR DEVELOPING
THUNDERSTORM CELLS THIS AFTERNOON. CLOUDS WILL BREAK UP AND BEGIN
TO LIFT TOWARD THE END OF THE PERIOD AS HIGH PRESSURE MOVES IN
FROM THE WEST. 75
PRELIMINARY POINT TEMPS/POPS
PDT 47 67 46 66 / 40 10 0 20
ALW 50 68 49 66 / 50 20 0 20
PSC 45 72 46 71 / 20 0 0 10
YKM 42 72 46 70 / 10 0 10 10
HRI 46 71 48 69 / 20 10 0 10
ELN 39 68 44 66 / 10 0 20 10
RDM 38 63 35 61 / 50 10 10 20
LGD 46 63 39 61 / 60 30 0 30
GCD 45 64 38 59 / 40 20 0 20
DLS 48 71 51 70 / 30 10 20 40
PDT WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
SHORT TERM...75
LONG TERM....75
AVIATION...75
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