377
FXUS66 KPDT 061910
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1210 PM PDT TUE OCT 6 2026
KEY MESSAGES
- DRY AND ABOVE NORMAL TEMPERATURES THROUGH THE WEEK.
- BREEZY AND FIRE WEATHER CONCERNS FRIDAY.
- WEEKEND RAIN CHANCES, WITH MOUNTAIN SNOWFALL POSSIBLE.
DISCUSSION
CURRENT RADAR AND VISIBLE SATELLITE IMAGERY SHOWS DRY CONDITIONS
UNDER MOSTLY CLEAR SKIES. THIS IS IN RESPONSE TO A BUILDING
UPPER LEVEL RIDGE OFFSHORE THAT WILL KEEP CONDITIONS DRY AND
TEMPERATURES SLIGHTLY COOLING THROUGH THE WEEK AS NORTHWEST FLOW
ALOFT ENHANCES. A WEAK, THERMAL TROUGH IS EXPECTED TO BUILD
ALONG THE COAST ON WEDNESDAY, WHICH WILL ALLOW FOR LIGHT EAST
WINDS THROUGH THE COLUMBIA BASIN AND GORGE. THIS THERMAL TROUGH
WILL STRENGTHEN ON THURSDAY TO PROVIDE BREEZIER WINDS THROUGH
THE COLUMBIA GORGE, PRIMARILY WEST OF THE HOOD RIVER AREA. THESE
EAST WINDS WILL KEEP OVERNIGHT HUMIDITY RECOVERIES IN THE
30-50% RANGE ACROSS PORTIONS OF CENTRAL OREGON, JOHN DAY
BASIN/HIGHLANDS, BLUE MOUNTAINS, ELKHORNS, AND THE CASCADE GAPS.
THE RIDGE OF HIGH PRESSURE SHIFTS FURTHER WEST AND INTO THE
EASTERN PACIFIC LATE THURSDAY TO FRIDAY, OPENING THE DOOR TO A
DROPPING UPPER LEVEL TROUGH FROM THE GULF OF ALASKA. DUE TO THE
INFLUENCE OF THE DEPARTING RIDGE AND INCUMBENT DRY AIR FROM THE
EAST WINDS WEDNESDAY AND THURSDAY, LIMITED RAIN IS EXPECTED AS
WINDS WILL BE THE PRIMARY CONCERN. THE GFS AND NAM ADVERTISE A
PRESSURE GRADIENT OF 11-12.5 MB OVER THE CASCADES, WHICH
SUGGESTS WINDS REACHING ADVISORY CRITERIA. THE NBM SHOWCASES A
20-40% CHANCE OF SUSTAINED WINDS OF 30 MPH OR GREATER, WITH A
30-60% CHANCE OF GUSTS REACHING 45 MPH OR GREATER ACROSS THE
SIMCOE HIGHLANDS, KITTITAS VALLEY, AND PORTIONS OF THE COLUMBIA
BASIN ON FRIDAY. AFTERNOON HUMIDITIES WILL DROP INTO THE TEENS
ACROSS THE JOHN DAY BASIN AND PORTIONS OF CENTRAL OREGON ON
FRIDAY, WHICH MAY LEAD TO ISOLATED FIRE CONTROL AND SPREAD
CONCERNS AS WELL. THESE ELEVATED WINDS MAY ALSO PROVIDE AREAS OF
BLOWING DUST, POTENTIALLY DECREASING VISIBILITIES AND CAUSING
TRAVEL CONCERNS ALONG THE INTERSTATE 90, 84, AND 82 CORRIDORS.
GUIDANCE IS CONTINUING TO STRUGGLE WITH THE OVERALL STRENGTH OF
THE INCOMING UPPER LEVEL TROUGH ON FRIDAY, HIGHLIGHTED BY A 73%
ENSEMBLE MEMBER VARIANCE IN SYSTEM STRENGTH. 60% OF ENSEMBLE
MEMBERS SHOW A SIGNIFICANT SYSTEM MOVING THROUGH THE AREA DURING
PEAK AFTERNOON HOURS ON FRIDAY, WHICH ALIGNS WITH A
SLIGHT POTENTIAL FOR ADVISORIES THROUGH PORTIONS OF THE BASIN.
24% OF MEMBERS ALSO SUGGEST A SLIGHTLY LATER PASSING OF THE
SYSTEM, ALLEVIATING SOME WIND CONCERNS AND PRODUCING SUB-
ADVISORY WINDS. THE PRIMARY MOISTURE SUPPLY FOR THIS SYSTEM IS
THE REMNANTS OF HURRICANE RACHEL AS IT TURNS NORTH AND
TRANSITIONS TO SUB-TROPICAL STATUS AS THE TROUGH STRENGTHENS AND
DROPS SOUTH THROUGH THE PACIFIC NORTHWEST. THE STRONGER TROUGH
IS MORE EFFICIENT AT BRINGING MOISTURE FROM RACHEL'S REMNANTS
NORTH AND ACROSS THE AREA, BUT RAIN AMOUNTS ARE STILL RATHER LOW
AND BELOW A WETTING RAIN FOR MOST OF THE REGION. CURRENTLY, 89%
OF ENSEMBLE MEMBERS SHOW THE MAJORITY OF THE AREA RECEIVING
MEASURABLE RAINFALL (0.01" OR GREATER) SATURDAY, WITH MORE
WIDESPREAD MEASURABLE RAIN ON SUNDAY. REGARDLESS OF OUTCOME,
48-HOUR RAIN AMOUNTS LOOK TO STAY AROUND 0.05" OR LESS ACROSS
LOWER ELEVATIONS, AND UP TO 0.1-0.15" FOR HIGHER TERRAIN ACROSS
THE BLUE MOUNTAINS SATURDAY THROUGH SUNDAY. SNOW LEVELS WILL
ALSO BE IN DECLINE OVER THE WEEKEND, REACHING AROUND 3,000 FEET
ON SUNDAY - SO THERE IS ALSO POTENTIAL FOR SNOWFALL OVER HIGHER
TERRAIN SATURDAY NIGHT INTO SUNDAY MORNING. A FREEZE CONCERN IS
ALSO PRESENT ACROSS CENTRAL OREGON AND PORTIONS OF THE COLUMBIA
BASIN STARTING SUNDAY. THE NBM ADVERTISES A 50-70% CHANCE OF
FREEZING TEMPERATURES MONDAY MORNING ACROSS CENTRAL OREGON AND
THE BLUE MOUNTAIN FOOTHILLS, SO FREEZE PRODUCTS MAY BE
WARRANTED. STAY TUNED. 75
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
VFR CONDITIONS PREVAIL. WINDS ARE VARIABLE THROUGH MOST OF THE
REGION. PREVAILING WINDS WILL BE CALM AND FOLLOW TYPICAL DIURNAL
PATTERS. SKY COVER IS LIGHT WITH MOSTLY HIGH BASE CLOUDS AROUND
25,000FT.
PRELIMINARY POINT TEMPS/POPS
PDT 46 79 46 80 / 0 0 0 0
ALW 51 80 52 81 / 0 0 0 0
PSC 45 80 46 81 / 0 0 0 0
YKM 49 80 50 82 / 0 0 0 0
HRI 45 80 45 81 / 0 0 0 0
ELN 46 77 49 79 / 0 0 0 0
RDM 41 82 41 83 / 0 0 0 0
LGD 46 84 47 84 / 0 0 0 0
GCD 48 89 49 88 / 0 0 0 0
DLS 52 84 53 85 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...75
AVIATION...18
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