474
FXUS66 KPDT 160519
AFDPDT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PENDLETON OR
1019 PM PDT THU OCT 15 2026
KEY MESSAGES
1. DRY AND WARM CONDITIONS THROUGH THE END OF THE WEEK
2. GUSTY CONDITIONS THROUGH THE GRANDE RONDE VALLEY TOMORROW AFTERNOON
WITH ELEVATED FIRE RISK.
3. TROUGH DEVELOPS THROUGH AREA BEGINNING MONDAY WITH THE
POTENTIAL FOR RAINFALL ALONG BLUE MOUNTAINS
DISCUSSION
CLEAR SKIES CONTINUE TO BE PRESENT OVER THE REGION THANKS TO
CONTINUED UPPER-LEVEL RIDGING ALONG THE US WEST COAST. CURRENT
GUIDANCE TIMING SUGGESTS THAT THE RIDGE WILL REMAIN PRESENT IN
THE REGION THROUGHOUT THE REST OF TODAY AND TOMORROW,
TRANSITIONING TO ZONAL FLOW ALONGSIDE A SHORTWAVE TROUGH
TOMORROW NIGHT INTO SATURDAY MORNING. SAID SHORTWAVE TROUGH WILL
LIKELY (GREATER THAN 50% CHANCE) BE POSITIONED ALONG THE US-
CANADA BORDER, LIMITING PRECIPITATION CHANCES THROUGH THE REGION
(LESS THAN 20%). AS THE PRIMARY TROUGH AXIS CONTINUES TO MOVE
EASTWARD, DETERMINISTIC GUIDANCE HIGHLIGHTS A FAVORABLE SURFACE
PRESSURE GRADIENT ACROSS THE BLUE MOUNTAINS FOR GUSTY
SOUTH/SOUTHEAST WINDS TOMORROW INTO SATURDAY MORNING, ESPECIALLY
AROUND THE GRANDE RONDE VALLEY. NBM ENSEMBLE PROBABILITIES FOR
THIS TIME SHOW A HIGH CHANCE (AROUND 75%) OF LOCALIZED SUSTAINED
WINDS IN EXCESS OF 20 MPH, WITH A MODERATE CHANCE (UP TO 50%)
OF LOCAL GUSTS IN EXCESS OF 40MPH IN THE GRANDE RONDE VALLEY.
GIVEN THE WINDY CONDITIONS IN THESE REGIONS, AS WELL AS RH
VALUES AROUND 15-20% FOR MUCH OF THE BLUE MOUNTAINS IN THE
AFTERNOON, AN ELEVATED FIRE RISK IS PRESENT FOR THESE REGIONS
FOR FRIDAY AFTERNOON INTO THE EVENING.
AS ZONAL FLOW CONTINUES THROUGHOUT THE WEEKEND, AN UPPER LEVEL
TROUGH WILL BEGIN TO DEVELOP OFFSHORE SUNDAY NIGHT THROUGH
MONDAY, MOVING INTO THE PACNW REGION MONDAY NIGHT INTO TUESDAY.
ENSEMBLE GUIDANCE IS CONFIDENT (GREATER THAN 75% CHANCE) THAT A
TROUGH WILL OCCUR, HOWEVER SIGNIFICANT VARIABILITY STILL EXISTS
REGARDING TROUGH STRENGTH AND TIMING. BECAUSE OF THIS
UNCERTAINTY IN TROUGH DEPTH, THERE IS LOW CONFIDENCE (AROUND
30-40%) IN CURRENT RAINFALL AMOUNTS. IN SCENARIOS WHERE THE
TROUGH IS DEEPER, WITH A CLOSED LOW DEVELOPING NEAR CALIFORNIA,
RAINFALL IS LIMITED TO NON-WETTING AMOUNTS ALONG THE BLUE
MOUNTAINS. IN SCENARIOS WITH A MORE NORTHWARD LOW OR OPEN WAVE
SETUP, WETTING RAINFALL IN THESE REGIONS IS MORE LIKELY WITH THE
IMPROVED MOISTURE FLOW PATTERN. LINGERING RAINFALL IS POSSIBLE
INTO WEDNESDAY AND THURSDAY AS THE TROUGH MOVES EASTWARD AND
WEAKENS, HOWEVER THE SAME MODEL VARIABILITY CONCERNS AND LOW
CONFIDENCE STILL APPLIES.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
VFR CONDITIONS PREVAIL.
WINDS FOLLOW A DIURNAL PATTERN.
PRELIMINARY POINT TEMPS/POPS
PDT 37 73 41 69 / 0 0 0 0
ALW 44 74 49 69 / 0 0 0 0
PSC 38 69 37 71 / 0 0 0 0
YKM 42 70 42 69 / 0 0 0 0
HRI 37 70 38 70 / 0 0 0 0
ELN 38 67 39 61 / 0 0 0 0
RDM 33 79 34 66 / 0 0 0 0
LGD 41 71 45 70 / 0 0 0 0
GCD 36 76 37 72 / 0 0 0 0
DLS 44 75 46 69 / 0 0 0 0
PDT WATCHES/WARNINGS/ADVISORIES
WA...NONE.
OR...NONE.
DISCUSSION...21/71
AVIATION...18
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