783 
FNUS76 KPDT 050102
FWSPDT

Spot Forecast for Marks Creek...ODF
National Weather Service Pendleton OR
602 PM PDT Thu Sep 4 2025

Forecast is based on forecast start time of 0600 PDT on September 05. 
***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.

...RED FLAG WARNING IN EFFECT FROM 1 PM TO 11 PM PDT FRIDAY...

.DISCUSSION...T-storms Chcs will continue through 11PM tonight.

Hot, dry and unstable conditions will persist over the fire area
through Friday evening. Chc of lightning is 20-25% through Sat.
T-storms will be dry with little precip increasing in chcs in the 
afternoon and are expected to be wetter Sat. Fri min RHs will be 
below 30% increasing to 40% with overnight recoveries being above 
60%. Winds will be mostly US/UV during the day and DS/DV overnight. 
The inversion Friday is expected to break around 1030AM and instability 
will quickly follow.  

.FRIDAY...

Sky/weather.........Mostly sunny (40-50 percent) then becoming 
                    mostly cloudy (70-80 percent). Haze early in 
                    the morning. Haze late in the afternoon. Chance 
                    of showers and slight chance of thunderstorms 
                    late in the morning. 
CWR.................0 percent increasing to 39 percent. 
Chance of lightning.23 percent. 
Max temperature.....83-86. 
Min humidity........24-29 percent. 
Wind (20 ft)........Upslope/Up-valley. Gusty and erratic winds expected 
                    near thunderstorms beginning around 11 AM. 
Ridgetop wind.......Upslope/Up-valley. Gusty and erratic winds expected 
                    near thunderstorms beginning around 11 AM. 
Mixing height.......7500 ft AGL. 
Transport winds.....East 6 to 9 mph becoming light. 
Ventilation Index...Poor (50) increasing to fair (480) in the 
                    afternoon. 

TIME (PDT)      6 AM   8 AM   10 AM  NOON   2 PM   4 PM   
Chc of ltng (%).10     10     10     20     20     20     
Temp............61     64     75     81     83     82     
RH..............49     48     37     33     30     31     
20 ft wind......NE 3   NE 4   NE 4   NE 4   NE 4   NE 4   
20 ft wind gust.       5      5      7      7      7      

.FRIDAY NIGHT...

Sky/weather.........Mostly cloudy (75-85 percent). Haze in the 
                    evening. Haze overnight. Chance of rain showers 
                    and slight chance of thunderstorms in the 
                    evening, then slight chance of rain showers 
                    late in the evening. 
CWR.................39 percent decreasing to 2 percent late in the 
                    evening. 
Chance of lightning.23 percent. 
Min temperature.....Around 60. 
Max humidity........61-66 percent. 
Wind (20 ft)........Downslope/Down-valley. Gusty and erratic winds 
                    expected near thunderstorms through 11PM. 
Ridgetop wind.......Downslope/Down-valley. Gusty and erratic winds 
                    expected near thunderstorms through 11PM.  
Mixing height.......900 ft AGL in the evening then 500 ft AGL early 
                    in the morning. 
Transport winds.....Light winds becoming south around 8 mph early 
                    in the evening, then shifting to the northeast 
                    6 to 10 mph late in the evening. 
Ventilation Index...Poor (80) decreasing to poor (40) overnight. 

.SATURDAY...

Sky/weather.........Partly sunny (60-70 percent). Slight chance of 
                    showers in the morning. Chance of showers late 
                    in the morning. Slight chance of thunderstorms 
                    late in the afternoon. Haze early in the 
                    morning. 
CWR.................0 percent increasing to 12 percent late in the 
                    morning. 
Chance of lightning.23 percent. 
Max temperature.....Around 80. 
Min humidity........32-37 percent. 
Wind (20 ft)........Upslope/Up-valley. Gusty and erratic winds expected 
                    near thunderstorms beginning around 8AM. 
Ridgetop wind.......Upslope/Up-valley. Gusty and erratic winds expected 
                    near thunderstorms beginning around 8AM. 
Mixing height.......5800 ft AGL. 
Transport winds.....East around 6 mph shifting to the southeast 6 
                    to 8 mph early in the morning, then shifting to 
                    the north around 12 mph late in the afternoon. 
Ventilation Index...Poor (30) increasing to fair (330) in the 
                    afternoon. 

$$
Forecaster...Bennese
Requested by...Dana Skelly
Type of request...WILDFIRE
.TAG 2521347.0/PDT
.DELDT 09/04/25
.FormatterVersion 2.0.0
.EMAIL dana_skelly@firenet.gov,dana.skelly@usda.gov,rebecca.muessle@noaa.gov