804
FNUS76 KPDT 120534
FWSPDT
SPOT FORECAST FOR BIG HOLE FIRE...US FOREST SERVICE
NATIONAL WEATHER SERVICE PENDLETON OR
1034 PM PDT THU SEP 11 2025
FORECAST IS BASED ON FORECAST START TIME OF 0600 PDT ON SEPTEMBER 12.
***THUNDERSTORMS IMPLY GUSTY AND ERRATIC WINDS***
***WINDS ARE 20 FOOT 10-MINUTE AVERAGES***
***CWR-CHANCE OF WETTING RAIN 0.10 OR GREATER***
***VENTILATION INDEX IS DERIVED FROM THE
TRANSPORT WIND MULTIPLIED BY THE MIXING
HEIGHT IN 100'S OF FEET. INDEX CATEGORIES
ARE A GENERALIZED INDICATOR ONLY.***
IF YOU HAVE QUESTIONS OR CONCERNS WITH THIS FORECAST, PLEASE
CONTACT OUR OFFICE AT (541) 276-8134.
DISCUSSION
A WARMING, DRYING TREND IS ANTICIPATED FRIDAY THROUGH
SATURDAY AS A BRIEF RIDGE OF HIGH PRESSURE BUILDS OVER THE PACIFIC
NORTHWEST. WINDS WILL BE DIURNALLY AND TERRAIN-DRIVEN AND MOSTLY
LIGHT. OVERNIGHT RH RECOVERY IS EXPECTED TO BE EXCELLENT. CHANCES OF
SHOWERS AND THUNDERSTORMS ARE VERY LOW (<10%) WITH MOST ACTIVITY
EXPECTED FARTHER EAST OVER THE BLUE MOUNTAINS. A LOW-PRESSURE
SYSTEM WILL LIKELY (>80% CHANCE) ARRIVE OVER THE REGION BY SATURDAY
NIGHT, USHERING IN COOLER, SHOWERY CONDITIONS OVERNIGHT THROUGH SUNDAY.
FRIDAY
SKY/WEATHER.........MOSTLY SUNNY (15-35 PERCENT).
CWR.................0 PERCENT.
CHANCE OF LIGHTNING.3 PERCENT.
MAX TEMPERATURE.....73-76.
MIN HUMIDITY........35-40 PERCENT.
WIND (20 FT)........DRAINAGE WINDS 2-5 MPH EARLY MORNING, BECOMING
UPSLOPE WINDS 2-5 MPH LATE MORNING.
MIXING HEIGHT.......INCREASING TO 5500-6000 FT AGL BY AFTERNOON.
TRANSPORT WINDS.....VARIABLE 3-6 MPH.
VENTILATION INDEX...POOR (30) INCREASING TO POOR (150) IN THE
AFTERNOON.
TIME (PDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
CHC OF LTNG (%).0 0 0 0 0 0 0 0 0 0 0 0
TEMP............42 42 45 52 56 61 65 68 71 71 73 72
RH..............98 97 93 85 75 65 57 52 46 43 40 42
20 FT WIND DIR..NW NW W W W S S S W W W W
20 FT WIND SPD..4 4 4 4 4 4 4 4 4 4 4 4
20 FT WIND GUST.6 6 5 5 5 6 6 6 8 8 8 8
FRIDAY NIGHT
SKY/WEATHER.........MOSTLY CLEAR (5-25 PERCENT).
CWR.................0 PERCENT.
CHANCE OF LIGHTNING.1 PERCENT.
MIN TEMPERATURE.....39-42.
MAX HUMIDITY........93-98 PERCENT.
WIND (20 FT)........DRAINAGE WINDS 2-5 MPH.
MIXING HEIGHT.......DECREASING TO NEAR SURFACE OVERNIGHT.
TRANSPORT WINDS.....NORTHWEST 6-8 MPH SHIFTING TO THE WEST
4-6 MPH OVERNIGHT.
VENTILATION INDEX...POOR (140) DECREASING TO POOR (30) OVERNIGHT.
SATURDAY
SKY/WEATHER.........SUNNY (5-15 PERCENT).
CWR.................0 PERCENT.
CHANCE OF LIGHTNING.2 PERCENT.
MAX TEMPERATURE.....77-80.
MIN HUMIDITY........26-31 PERCENT.
WIND (20 FT)........DRAINAGE WINDS 2-5 MPH EARLY MORNING, BECOMING
UPSLOPE BY MID-MORNING, THEN BECOMING SOUTHWEST
TO WEST 4-8 MPH IN THE AFTERNOON.
MIXING HEIGHT.......INCREASING TO 7500-8000 FT AGL BY AFTERNOON.
TRANSPORT WINDS.....SOUTH WINDS 2-4 MPH EARLY MORNING, BECOMING
SOUTHWEST 6-9 MPH BY LATE MORNING.
VENTILATION INDEX...POOR (30) INCREASING TO FAIR (470) IN THE
AFTERNOON.
FORECASTER...PLUNKETT
REQUESTED BY...ELLA NICHOLS
TYPE OF REQUEST...WILDFIRE
.TAG 2521851.0/PDT
.DELDT 09/12/25
.FORMATTERVERSION 2.0.0
.EMAIL ELLA.NICHOLS12@GMAIL.COM,THOMAS.ALVUT@USDA.GOV
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