115
FNUS76 KPDT 220300
FWSPDT

Spot Forecast for Flat Fire...USFS
National Weather Service Pendleton OR
800 PM PDT Thu Aug 21 2025

Forecast is based on forecast start time of 2000 PDT on August 21.
***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...Dry conditions are expected through the weekend,
with increasingly hot temperatures.

Winds will be light tonight but could gust in the 15 to 20 mph
range Friday afternoon and evening. Winds will be lighter Friday night and
Saturday.

MIN RH values will be in the 10 to 15 percent range Friday and Saturday, with
moderate recoveries overnight.

.REST OF TONIGHT...

Sky/weather.........Mostly clear (0-10 percent).
CWR.................0 percent.
Chance of lightning.0 percent.
Min temperature.....55-58.
Max humidity........38-43 percent.
Wind (20 ft)........Northwest winds 5 to 8 mph shifting to the west
                    around 5 mph early in the morning.
Ridgetop wind.......East wind 10 to 15 mph.
Mixing height.......500 ft AGL.
Transport winds.....North 6 to 14 mph early in the evening becoming
                    light.
Ventilation Index...Fair (300) decreasing to poor (40) overnight.

TIME (PDT)      8 PM   10 PM  MIDNGT 2 AM   4 AM   6 AM
Chc of ltng (%).0      0      0      0      0      0
Temp............80     72     68     64     59     55
RH..............25     28     31     34     38     42
20 ft wind......N 8    N 8    NW 8   NW 5   NW 5   W 5
20 ft wind gust.12     12     12     7      7      6

.FRIDAY...

Sky/weather.........Sunny (5-15 percent).
CWR.................0 percent.
Chance of lightning.0 percent.
Max temperature.....92-95.
Min humidity........11-16 percent.
Wind (20 ft)........West winds 5 to 7 mph shifting to the north 5
                    to 14 mph early in the morning.
Ridgetop wind.......East wind 10 to 15 mph becoming northeast in
                    the afternoon. Gusts up to 20 mph in the afternoon
                    and evening.
Mixing height.......5100 ft AGL.
Transport winds.....Light winds becoming northeast 5 to 12 mph
                    early in the morning, then shifting to the
                    north around 17 mph late in the afternoon.
Ventilation Index...Poor (30) increasing to fair (340) in the
                    afternoon.

.FRIDAY NIGHT...

Sky/weather.........Mostly clear (15-25 percent).
CWR.................0 percent.
Chance of lightning.0 percent.
Min temperature.....59-62.
Max humidity........31-36 percent.
Wind (20 ft)........North winds 5 to 15 mph shifting to the
                    northwest 5 to 11 mph late in the evening, then
                    becoming light early in the morning.
Ridgetop wind.......Northeast wind 10 to 15 mph with gusts to 20 mph
                    in the evening, then becoming east around 10 mph
                    by morning.
Mixing height.......600 ft AGL.
Transport winds.....North 12 to 17 mph becoming light.
Ventilation Index...Fair (350) decreasing to poor (40) overnight.

.SATURDAY...

Sky/weather.........Mostly sunny (35-45 percent).
CWR.................0 percent.
Chance of lightning.5 percent.
Max temperature.....93-96.
Min humidity........11-16 percent.
Wind (20 ft)........Light winds becoming southwest 5 to 7 mph early
                    in the morning, then shifting to the northeast
                    5 to 10 mph late in the morning.
Ridgetop wind.......East wind around 10 mph becoming northeast in
                    the afternoon.
Mixing height.......4900 ft AGL.
Transport winds.....Light winds becoming east 6 to 7 mph late in
                    the morning, then shifting to the north around
                    9 mph late in the afternoon.
Ventilation Index...Poor (30) increasing to fair (210) in the
                    afternoon.

$$
Forecaster...Nierenberg
Requested by...Lucas Garcia
Type of request...WILDFIRE
.TAG 2520431.0/PDT
.DELDT 08/21/25
.FormatterVersion 2.0.0
.EMAIL lucas.garcia@usda.gov